■ '4''!
hfjIM-i
' ..'■: j$#
' -■•|4lt|l
MANUAL OF GEOLOGY.
CARBONIFEROUS AGE. —Pages 283 and 333,
MANUAL
OF
GEOLOGY:
TREATING OF THE PRINCIPLES OF THE SCIENCE
WITH SPECIAL REFERENCE TO
AMERICAN GEOLOGICAL HISTORY,
FOR THE USE OF COLLEGES, ACADEMIES, AND SCHOOLS OF SCIENCE.
BY
JAMES D. DANA, M.A., LL.D.
SILUMAN PROFESSOR OF GEOLOGY AND NATURAL HISTORY IN YALE COLLEGE; AUTHOR OF
"A SYSTEM OF MINERALOGY," OF REPORTS OF WILKES'S EXPLORING EXPEDITION
ON GEOLOGY, ON ZOOPHYTES, AND ON CRUSTACEA, ETC.
Licet jam oculis quodammodo contemplari pulchritudinem rerum earum,
quas divina provideutia dicimua constitutas.—CiC.
Nunquam aliud natura aliud sapientia dicet.—Juv.
ILLUSTRATED BY A CHART OF THE WORLD, AND OVER ONE THOUSAND
FIGURES, MOSTLY FROM AMERICAN SOURCES.
REVISED EDITION.
PHILADELPHIA:
PUBLISHED BY THEODORE BLISS & CO.
LONDON: TRUBNER & CO.
1866.
Entered according to Act of Congress, in the year 1862, by
THEODORE BLISS & CO.
in the Clerk's Office of the District Court of the United States for the Eastern
District of Pennsylvania.
ELECTKOTYPED BY L. JOHNSON AND CO.
PHILADELPHIA.
C. SHERMAN & SON PRINTERS.
PREFACE.
Two reasons have led the author to give this Manual its
American character: a desire to adapt it to the wants of Ame¬
rican students, and a belief that, on account of a peculiar sim¬
plicity and unity, American Geological History affords the best
basis for a text-book of the science. North America stands
alone in the ocean, a simple isolated specimen of a continent
(even South America lying to the eastward of its meridians),
and the laws of progress have been undisturbed by the conflicting
movements of other lands. The author has, therefore, written
out American Geology by itself, as a continuous history. Facts
have, however, been added from other continents so far as was
required to give completeness to the work and exhibit strongly
the comprehensiveness of its principles.
It has been the author's aim to present, for study, not a series
of rocks with their dead fossils, but the successive phases in the
history of the earth,—its continents, seas, climates, life, and the
various operations in progress. Dynamical Geology, contrary
to the views of some geologists, has been placed after the strati-
graphical or historical portion. It will, however, be found that
through the latter the facts have been followed by statements
and explanations of principles; so that the student, on reaching
the pages treating of Geological Causes, will have already
learned much of what they contain.
As many readers may not be familiar with Zoology, a review
of the classification of animals, with many illustrations, has been
given before entering upon the History of the ancient life of the
world.
vii
viii
preface.
The Manual has been adapted to two classes of students,—
the literary and scientific,—by printing the details in finer
type. The convenience of a literary class has been further pro¬
vided for by the addition of a brief synopsis of the work, in
which each head is made to present a subject, or question, for
special attention.
In the preparation of the American part of the volume, the
author has freely used the reports of the various geological
surveys of the country, the memoirs published in the different
scientific journals and transactions, and other works bearing on
the subject. He has also drawn from his own Memoirs and Ex¬
ploring Expedition Reports, especially on the subjects of Coral
islands,—Volcanic islands,—the Formation of Valleys by the
action of rivers,—the General Features of the Globe, and their
origin,—American Geological history,—and the Temperature
of the Globe, as exhibited on the Physiographic Chart.
The illustrations of American Palaeozoic life have been
largely copied from the Reports of Professor Hall. A few of
the Palaeozoic figures, and many of later periods, are from
original drawings made by Mr. F. B. Meek, to whose artistic
skill and paleeontological science the work is, throughout, greatly
indebted. The drawings were nearly all made on the wood for
engraving by Mr. Meek; and the palaeontological pages have had
the benefit of his revision. The name of the engraver, Lock-
wood Sajstford, of New Haven, also deserves mention in this
place.
In selecting figures of foreign fossils for the Manual, those
used in Lvell's and other standard English works have, with
few exceptions, been avoided, so that the student owning any
of those volumes will have additional illustrations of the
science. Many of the foreign figures are from the beautifully
illustrated " Palbontologie et Geologic" of Alcide d'Orbigny.
The author would make acknowledgments to his countrymen
for the readiness with which they have furnished aid, whenever
appealed to, and especially, for oft-repeated favors, to J. P.
Lesley, of Philadelphia; J. S. Newberry, of Cleveland, Ohio;
Arnold Guyot, of Princeton, N.J.; L. Lesquereux, of Co¬
lumbus, Ohio; E. Billings, of Montreal, Canada; E. Jewett,
PREFACE.
ix
of Albany, N.Y.; and W. C. Minor and Frank H. Bradley,
of New Haven. Mr. Bradley has given freely his constant as¬
sistance during the progress of the work through the press.
The author has endeavored to bring the volume into as small
a compass as is consistent with a proper exhibition of the
science; and if some find its pages too numerous, he feels con¬
fident that quite as many would prefer greater fulness. The
details introduced have seemed to be necessary in order that the
march of events might be appreciated.
Geology is rapidly taking its place as an introduction to the
higher history of man. If the author has sought to exalt a
favorite science, it has been with the desire that man—in whom
geological history had its consummation, the prophecies of the
successive ages their fulfilment—might better comprehend his
own nobility and the true purpose of his existence.
New Haven, Ct., November 1, 1862.
PEEFACE TO SECOND EDITION.
The Manual has here received such alterations as seemed to
be required by the results of recent Geological research. The
general arrangement and paging of the volume remain, how¬
ever, unchanged, excepting in the Appendix, where two sec¬
tions are introduced—one on an Insect from the American Car¬
boniferous formation, and the other on the long-tailed or rep¬
tilian Bird of Solenhofen. Each of these sections is illustrated
by a wood-cut, the Insect having special interest from the re¬
markable perfection of the specimen and its Geological age ; and
the Bird being an anomaly in its class, opening to science wholly
new views as to the nature of the ancient Birds of the world,
and the range of form under the Bird type.
TO INSTRUCTORS.
The "Brief Synopsis" of Appendix K. is intended to facilitate
the use of this Manual as a recitation-book. Lectures cannot well
be wholly dispensed with in the instruction of Natural or Physical
Science; but, with a work so full of illustrations as this, they may,
with great advantage, be altogether subordinate to recitations, espe¬
cially if the latter are accompanied with an exhibition of speci¬
mens. Through the use of fine type for the details of the Science,
the Manual is made to combine in one a small and a large book.
The topics presented in the " Synopsis" are, with few exceptions,
those of the former; and they are so prepared that each suggests
a question. A cursory perusal of the details in the smaller type is,
however, to be advised, as it will aid the student in acquiring precise
ideas. Even in scientific schools it may be best that the student
first go through the Manual with the Synopsis, and then, in a second
course, take up the Palasontology and Dynamics with greater
thoroughness.
Every Academy or other Institution teaching the Science should
have, at least, a small collection of specimens. Even twenty-five
dollars will purchase one (of Louis Ssemann, Paris, 45 Rue St. Andre-
des-Arts, or of Dr. A. Krantz, at Bonn on the Rhine) containing
specimens of nearly all the mineral species mentioned in the
Manual, and of the more common kinds of rocks, and another
twenty-five dollars, a collection of fossils that would be of great
service.
x
TABLE OF CONTENTS.
INTRODUCTION.
PAGE
Relations of the Science of Geology 1
Subdivisions of Geology 7
PART I.—Physiographic Geology.
1. The Earth's General Contour and Surface-Subdivisions 9
2. System in the Reliefs of the Land 23
3. System in the Courses of the Earth's Feature-Lines 30
4. System of Oceanic Movements and Temperature 39
5. System of Atmospheric Movements and Temperature 44
6. Distribution of Forest-Regions, Prairies, and Deserts 46
PART II— Lithological Geology.
1. Constitution of Rocks 49
1. Elements constituting Rocks 50
2. Minerals constituting Rocks 55
3. Kinds of Rocks 70
1. Fragmental Rocks, exclusive of Limestones 73
2. Metamorphic Rocks not Calcareous 74
3. Calcareous Rocks—Carbonates and Sulphates 84
4. Igneous Rocks 86
2. Condition, Structure, and Arrangement of Rock-Masses 90
1. Stratified Condition 90
1. Nature of Stratification 90
2. Structure of Layers 92
3. Positions of Strata 101
4. Order of Arrangement of Strata 112
2. Unstratified Condition—Veins—Dikes 117
xi
xii
CONTENTS.
PART III.—Historical Geology.
General Divisions in the History
1. AZOIC TIME or AGE
Review of the Animal Kingdom
Review of the Vegetable Kingdom
II. PALAEOZOIC TIME
I. Age of Mollusks, or Silurian Age
A. Lower Silurian
1. Potsdam or Primordial Period (Potsdam and
Calciferous Epochs)
[Review of the Order of Brachiopods
2. Trenton Period (Chazy and Trenton Epochs)
3. Hudson Period (Utica and Hudson River Epochs)
4. General Observations on the Trenton and
Hudson Periods
Disturbances closing the Lower Silurian Era, and
Geographical Results
B. American Upper Silurian
1. Niagara Period
1. Oneida Epoch
2. Medina Epoch
3. Clinton Epoch
4. Niagara Epoch
General Observations on the Niagara Period...
2. Salina Period (Leclaire and Saliferous Epochs)..
3. Lower Ilelderberg Period
Observations on the American Upper Silurian
C. Foreign Upper Silurian
II. Age of Fishes, or Devonian Age
1. American Subdivisions
1. Oriskany Period
2. Corniferous Period (Cauda-Galli, Schoharie, and
Upper Helderberg Epochs)
[Review of the Class of Fishes
3. Hamilton Period (Marcellus, Hamilton, and
Genesee Epochs)
4. Chemung Period (Portage and Chemung Epochs)
5. Cat skill Period
2. Foreign Devonian
3. General Observations on the Devonian Age
4. Disturbances closing the Devonian Age
CONTENTS. xiii
II. PALAEOZOIC TIME—(continued). page
III. Carboniferous Age 305
Subdivisions and American Distribution 305
1. Subcarboniferous Period 306
1. American 306
2. Foreign 318
3. Disturbances preceding the Carboniferous Pe¬
riod 320
2. Carboniferous Period 321
1. American 321
1. Epoch of the Millstone Grit 321
2. Epoch of the Coal Measures 322
[Review of the Class of Reptiles 343
2. Foreign 352
3. General Observations on the Carboniferous
Period 359
3. Permian Period 369
1. American 369
2. Foreign 372
IV. General Observations on the Palaeozoic Ages 377
1. Rocks—Sections of the American Palaeozoic Forma¬
tions in different States 377
2. American Geography 386
3. Oscillations of Level—Dislocations 388
4. Life 394
Disturbances closing Palaeozoic Time 403
1. American 403
2. Foreign 412
Transition from the Pakeozoic to the Mesozoic 414
III. MESOZOIC TIME 413
Reptilian Age 414
1. Triassic Period 414
1. American 414
[Review of the Class of Insects 420
[Review of the Class of Mammals 421
2. Foreign 433
3. General Observations 438
2. Jurassic Period 444
1. American 444
2. Foreign 446
3. General Observations 405
Xiv CONTENTS.
III. MESOZOIC TIME—(continued). page
3. Cretaceous Period 467
1. American 467
2. Foreign 479
3. General Observations 488
4. General Observations on the Reptilian Age 493
1. Time-Ratios 493
2. Geography 493
3. Life 494
5. Disturbances during and at the close of the Rep¬
tilian Age 502
IV. CENOZOIC TIME 505
Mammalian Age 505
1. Tertiary Period 506
1. American 506
2. Foreign 522
General Observations 530
2. Post-Tertiary Period 535
1. Glacial Epoch 535
1. American 535
2. Foreign 540
3. Fiords 541
4. General Observations 541
2. American Champlain Epoch 547
3. American Terrace Epoch 554
4. Foreign Champlain and Terrace Epochs 558
5. Life of the Post-Tertiary 558
6. General Observations on the Post-Tertiary 567
General Observations on the Cenozoic 568
1. Time-Ratios 568
2. Geography 568
3. Life 571
V. ERA OF MIND—AGE OF MAN 573
1. Rocks and Life 574
2. Changes of Level 586
VI. General Observations on Geological History 590
1. Length of Geological Time 590
2. Geographical Progress in North America 592
3. Progress of Life 592
1. System in the Progress of Life 592
2. Relations of the Progress to the Physical History of
the Globe 600
CONTENTS. XV
PAET IV.—Dynamical Geology,
PAGE
General Subdivisions 603
I. Life 604
1. Protective Effects 604
2. Transporting Effects 605
3. Destructive Effects 605
4. Contributions to Rock Formations 606
1. Peat Formations 613
2. Coral Formations 614
II. Cohesive Attraction—Crystallization 625
III. The Atmosphere 628
IV. Water 632
1. Fresh AVaters 632
1. Superficial Waters—Rivers and Smallev Lakes 632
1. General Observations 632
2. Mechanical Effects 635
1. Erosion 635
2. Transportation 642
3. Distribution—Alluvial Formations 644
2. Subterranean Waters—Artesian Wells—Land-Slides.. 647
2. The Ocean—including also Large Lakes 650
1. Oceanic Forces—Currents—Waves 650
2. Oceanic Effects 655
1. Erosion 655
2. Transportation 657
3. Distribution—Marine and Fluvio Marine Form¬
ations 650
4. Action over a Submerged Continent 665
3. Freezing and Frozen Water 667
1. Freezing Water 667
2. Ice of Rivers and Lakes • 667
3. Glaciers 667
4. Icebergs 677
4. Formation of Sedimentary Strata 678
5. Topographical Results of Erosion over Continents 679
V. IIeat 681
1. IIeat of the Globe 681
2. Volcanoes 684
3. Non-Volcanic Igneous Ejections 702
4. Metamorphism and Origin of Veins 711
xvi
CONTENTS.
VI. Movements of the Earth's Crust, and thejr Consequences 71G
7. Movements of the Earth's Crust—Plications—Mountains 716
2. Structural Peculiarities of Rocks 725
3. Earthquakes 728 *
4. Evolution of the Earth's General Features. 731
COSMOGONY "41
APPENDIX.
A. Animal Kingdom.—Distinctions of Animals and Plants—Proto¬
zoans 747
B. Hudson Period—Lorraine Shales.. 750
C. Devonian Age 750
D. Carboniferous Period 751
E. Jurassic Period.. 751
F. Glacial Epoch 753
G. Coral Reefs.—Rate of Growth—Florida Reefs—Chalk ...... 754
H. Progress of Life 755
I. Mineral Oil 756
J. Catalogue of American Localities of Fossils 757
K. Brief Synopsis of this Manual 759
L. Authorities of the Figures of Fossils, Sections, and Views 769
M. Scientific Nomenclature 774
INDEX 775
LIST OF ABBREVIATIONS.
Ag.—L. Agassiz.
B.—E. Billings.
Brngt.—Brongniart.
Con.—T. A. Conrad.
D'Orb.—Alcide d'Orbigny.
D.—J. D. Dana.
E. & II.—Edwards & Haime.
Ehr.—Ehrenberg.
Gopp.—Goppert.
H.—J. Hall.
H. & M.—Hall & Meek.
Hk.—E. Hitchcock.
L.—J. Leidy.
Lam.—Lamarck.
Lsqx.—L. Lesquereux.
Linn.—Linnmus.
M.—F. B. Meek.
M. & H.—Meek & Hayden.
Schp.—Schimper.
Shum.—Shumard.
Sow.—Sowerby.
Sternb.—Sternberg.
Suck.—Suckow.
T. & lis.—Tuomey & Holmes.
Ung.—Unger.
Van.—L. Vanuxem.
INTRODUCTION.
1. Kingdoms of nature.—Science, in her survey of the earth,
has recognized three kingdoms of nature,—the animal, the vege¬
table, and the inorganic; or, naming them from the forms charac¬
teristic of each, the animal-kingdom, the plant-kingdom, and the
crystal-kingdom. An individual in either kingdom has its sys¬
tematic mode of formation or growth.
The plant or animal, (1) endowed with life, (2). commences from
a germ, (3) grows by means of imbibed nutriment, and (4) passes
through a series of changes and gradual development to the adult
state, when (5) it evolves new seeds or germs, and (6) afterward
continues on to death and dissolution.
It has, hence, its cycle of growth and reproduction, and cycle
follows cycle in indefinite continuance.
The crystal is (1) a lifeless object, and has a simpler history: it
(2) begins in a nucleal molecule or particle; (3) it enlarges by
external addition or accretion alone; and (4) there is, hence, no
proper development, as the crystal is perfect, however minute;
(5) it ends in simply existing, and not in reproducing; and, (6)
being lifeless, there is no proper death or necessai-y dissolution.
Such are the individualities in the great kingdoms of nature
displayed upon the earth.
2. But the earth also, according to Geology, has been brought to
its present condition through a series of changes or progressive
formations, and from a state as utterly featureless as a germ.
Moreover, like any plant or animal, it has its special systems of
interior and exterior structure, and of interior and exterior condi¬
tions, movements, and changes; and, although Infinite Mind has
guided all events towards the great end,—a world for mind,—the
earth has, under this guidance and appointed law, passed through
a regular course of history or growth. Having, therefore, as a
sphere, its comprehensive system of growth, it is a unit or indivi¬
duality, not, indeed, in either of the three kingdoms of nature
which have been mentioned, but in a higher,—a World-Kingdom.
2 1
2
INTRODUCTION.
Every sphere in space must have had a related system of growth,
and all are, in fact, individualities in this Kingdom of Worlds.
Geology treats of the earth in this grand relation. It is as
much removed from Mineralogy as from Botany and Zoology. It
uses all these departments ; for the species under them are the
objects which make up the earth and enter into geological his¬
tory. The science of minerals is more immediately important to
the geologist, because aggregations of minerals constitute rocks,
or the plastic material in which the records of the past were made.
3. The earth, regarded as such an individuality in a world-king¬
dom, has not only its comprehensive system of growth, in which
strata have been added to strata, continents and seas defined,
mountains reared, and valleys, rivers, and plains formed, all in
orderly plan, but also a system of currents in its oceans and atmo¬
sphere,—the earth's circulating-system; its equally world-wide
system in the distribution of heat, light, moisture, and magnetism,
plants and animals ; its system of secular variations (daily, annual,
etc.) in its climate and all meteorological phenomena. In these
characteristics the sphere before us is an individual, as much
so as a crystal or a tree; and, to arrive at any correct views
on these subjects, the world must be regarded in this capacity.
The distribution of man and nations, and of all productions
that pertain to man's welfare, comes in under the same grand
relation ; for in helping to carry forward man's progress as a race
the sphere is working out its final purpose.
There are, therefore,
4. Three departments of science arising out of this indi¬
vidual capacity of the earth.
I. Geology, which treats of (1) the earth's structure, and (2) its
system of development.—the last including (1) its progress in
rocks, lands, seas, mountains, etc.: (2) its progress in all physical
conditions, as heat, moisture, etc.; (3) its progress in life, or its
vegetable and animal tribes.
II. Physiography, which begins where Geology ends,—that is,
with the adult or finished earth,—and treats (1) of the earth's final
surface-arrangements (as to its features, climates, magnetism, life,
etc.), and (2) its system of physical movements or changes (as
atmospheric and oceanic currents, and other secular variations in
heat, moisture, magnetism, etc.).
III. The earth with reference to man (including ordinary Geo¬
graphy) : (1) the distribution of races or nations, and of all pro¬
ductions or conditions bearing on the welfare of man or nations;
and (2) the progressive changes of races and nations.
INTRODUCTION.
3
The first considers the structure and growth of the earth ; the
second, its features and world-wide activities in its finished state;
the third, the fulfilment of its purpose in man, for whose pupil¬
age it was made.
5. Relation of the earth to the universe.—While recognizing the
earth as a sphere in a world-kingdom, it is also important to observe
that the earth holds a very subordinate position in the system of
the heavens. It is one of the smaller satellites of the sun,—its size
about 1-1400,000th that of the sun. And the planetary system to
which it belongs, although 3,000,000,000 of miles in radius, is but
one among myriads, the nearest star 7000 times farther off than
Neptune. Thus it appears that the earth is a very little object in
the universe. Hence we naturally conclude that the earth is but
a dependent part of the solar system; that as a satellite of the
sun, in conjunction with other planets, it could no more have
existed before the sun, or our planetary system before the uni¬
verse of which it is a part, than the hand before the body which
it obediently attends.
Although thus diminutive, the laws of the earth are the laws of
the universe. One of the fundamental laws of matter is gravita¬
tion ; and this we trace not only through our planetery system,
but among the fixed stars, and thus know that one law pervades
the universe.
The rays of light which come in from the remote limits of space
are a visible declaration of unity; for this light depends on mole¬
cular vibrations,—that is, the ultimate constitution and mode of
action of matter ; and by the identity of its principles or laws,
whatever its source, it proves the essential identity of the molecules
of matter.
Meteoric stones are specimens of celestial bodies occasionally
sent to us from the heavens. They exemplify the same chemical
and crystallographic laws as the rocks of the earth, and have
afforded no new element or principle of any kind.
The moon presents to the telescope a surface covered with the
craters of volcanoes, having forms that are well illustrated by some
of the earth's volcanoes, although of immense size. The principles
exemplified on the earth are but repeated in her satellite.
6. Thus, from gravitation, light, meteorites, and the earth's satel¬
lite, we learn that there is oneness of law through space. The
elements may differ in different systems, but it is a difference such
as exists among known elements, and could give us no new funda¬
mental laws. New crystalline forms might be found in the depths
of space, but the laws of crystallography would be the same that
4
INTRODUCTION.
are displayed before us among the crystals of the earth. A text¬
book on Crystallography, Physics, or Celestial Mechanics, printed
in our printing-offices, would serve for the universe. The universe,
if open throughout to our explorations, would vastly expand our
knowledge, and science might have a more beautiful superstruct¬
ure, but its basement-laws would be the same.
The earth, therefore, although but an atom in immensity, is
immensity itself in its revelations of truth ; and science, though
gathered from one small sphere, is the deciphered law of all
spheres.
It is well to have the mind deeply imbued with this thought
before entering upon the study of the earth. It gives grandeur
to science and dignity to man, and will help the geologist to
apprehend the loftier characteristics of the last of the geological
ages.
7. Special aim of geology, and method of geological reasoning.
—Geology is sometimes defined as the science of the structure of
the earth. But the ideas of structure and origin of structure are
inseparably connected, and in all geological investigations they go
together. Geology had its very beginning and essence in the idea
that rocks were made through secondary causes ; and its great aim
has ever been to study structure in order to comprehend the
earth's history. The science, therefore, is a historical science.
It finds strata of sandstone, clay-rock, and limestone, lying
above one another in many successions ; and, observing them in
their order, it assumes, not only that the sandstones were made
of sand by some slow process, clayey rocks of clay, and so on, but
that the strata were successively formed ; that, therefore, they belong
to successive periods in the earth's past; that, consequently, the
lowest beds in a series were the earliest beds. It hence infers,
further, that each rock indicates some facts respecting the condi¬
tion of the sea or land at the time it was formed, one condition
originating sand deposits, another clay deposits, another lime,—and,
if the beds extend over thousands of square miles, that the several
conditions prevailed uniformly to this same extent at least. The
rocks are thus regarded as records of successive events in the
history,—indeed, as actual historical records ; and every new fact
ascertained by a close study of their structure, be it but the occur¬
rence of a pebble, or a seam of coal, or a bed of ore, or a crack, or
any marking whatever, is an addition to the records, to be inter¬
preted by careful st.udy.
Thus every rock marks an epoch in the history; and groups of
rocks, periods ; and still larger groups, ages; and so the ages which
INTRODUCTION.
5
reach through geological time, are represented in order by the
rocks that extend from the lowest to the uppermost of the
series.
8. If, now, the great beds of rock, instead of lying in even hori¬
zontal layers, are much folded up, or lie inclined at various angles,
or are broken and dislocated through hundreds or thousands
of feet in depth, or are uplifted into mountain-elevations, they
bear record of still other events in the great history; and should
the geologist, by careful study, learn how the great disturbance or
fracture was produced, or succeed in locating its time of occur¬
rence among the epochs registered in the rocks, he would have
interpreted the record, and added not only a fact to the history,
but also its full explanation. The history is, hence, a history of
the upturnings of the earth's crust, as well as of its more quiet
rock-making.
If, in addition, a fossil shell, or coral, or bone, or leaf, is found in
one of the beds, it is a relic of some species that lived when that
rock was forming ; it belongs to that epoch in the world repre¬
sented by the particular rock containing it, and tells of the life
of that epoch ; and if numbers of such organic remains occur
together, they enable us to people the seas or land, to our imagi¬
nation, with the very life that belonged to the ancient epoch.
Moreover, as such fossils are common in a large number of the
strata, from the lowest containing signs of life to the top,—that is,
from the oldest beds to the most recent,—by studying out the
characters of these remains in each, we are enabled to restore, to
our minds, to some extent, the population of all the epochs as
they follow one another in the long scries. The strata are thus
not simply records of moving seas, sands, clays, and pebbles, and
disturbed or uplifted strata, but also of the living beings that
have in succession occupied the land or waters. The history is a
history of the life of the globe, as well as of its rock-formations ;
and the life-history is the great topic of Geology: it adds tenfold
interest to the other records of the dead rocks.
These examples are sufficient to explain the basis and general
bearing of geological history.
The method of interpreting the records rests upon the simple principle that rocks
were made as they are no\y made, and that life lived in olden time as it now lives;
and, further, the mind is forced into receiving the conclusions arrived at by its own
laws of action.
For example, we go to the sea-shore, and observe the sands thrown up by the
waves; note how the wash of the waves brings in layer upon layer, though with
many irregularities; how the progressing waters raise ripples over the surface,
which the next wave buries beneath other sands; how such sand-beds gradually
6
INTRODUCTION,
increase in extent; how they are often continued out scores of miles beneath the
sea, as the bottom of the shallow shore-waters; and that these submerged beds are
formed through constant depositions from the ever-moving waters. Then we go
among the hard rocks, and find strata made of sand in irregular layers, much like
those of the beach; and on opening some of the layers we discover ripple-marks
covering the surface, as distinct and regular as if just made by the waves; or, in
another place, we find the strata made up of regular layers of sand and clay alter¬
nating, such as form from the gradual settling of the muddy material emptied into
the ocean by rivers,—or, in another place, layers of rounded, water-worn pebbles,
such as occur beneath rapidly-moving waters, whether of waves or rivers. We
remark that these hard rocks differ from the loose sand, clay, or pebbly deposits
simply in being consolidated into a rock. Then, in other places, we discover these
sand-deposits in all states of consolidation, from the soft, movable sand,
through a half-compacted condition, to the gritty sandstone; and, further, wc
discover, perhaps, the very means of this consolidation, and see it in its pro¬
gress, making rock out of sand or clay. By such steps as these the mind is
borne along irresistibly to the conclusion that rocks were slowly made through
commonplace operations.
We may see, on another sea-shore, extensive beds of limestone forming from
shells and corals, having as firm a texture as any marble; we may watch the
process of accumulation from the growth of corals and the wear of the waves,
and find the remains of corals and shells in the compact bed. If we then meet
with a limestone over the continent containing remains of corals, or shells, no
firmer, not different in composition, but every way like the coral reef-rock, or
the shell-rock of other regions, the mind, if allowed to act at all, will infer
that the ancient limestone was as much a slowly-formed rock, made of corals,
or shells, as the limestone of coral seas.
In a volcanic district, we witness the melted rock poured out in wide-spread
layers and cooling into compact rock, and learn, after a little observation, that
just such layers piled upon one another make the great volcanic mountain,
although it may be 10,000 feet in height. We remark, further, that the frac¬
tured crust in those regions has often let out the lava to spread the surface
with rock, even to great distances from the crater.
Should wc, after this, discover essentially the same kind of rock in wide¬
spread beds, and trace out the fractures filled with it, leading downward
through the subjacent strata, as if to some seat of fires, and discover marks of
fire in the baking of the underlying beds, we use our reason in the only legiti¬
mate way when we conclude that these beds were thrown out melted, even
though they may be far from any volcanic centre.
If we see skeletons buried in sand and clay that we do not doubt arc real
skeletons of familiar animals, and then in a bed of rock discover other skele¬
tons, but of unfamiliar animals, yet with every bone a true bone in form, tex¬
ture, and composition, and every joint and limb modelled according to the plan
in known species, we pass, by an unavoidable step, to the belief that the last is
a relic of an animal as well as the former, and that it lies in its burial-place,
although that burial-place be now the solid rock.
These few examples elucidate the mode of reasoning upon which geological
deductions are based.
INTRODUCTION.
7
9. In using the present in order to reveal the past, we assume that
the forces in the world are essentially the same through all time ;
for these forces are based on the very nature of matter, and could
not have changed. The ocean has always had its waves, and those
waves have ever acted in the same manner. Running water on
the land has ever had the same power of wear and transportation
and mathematical value to its force. The laws of chemistry, heat,
electricity, and mechanics have been the same through time.
The plan of living structures has been fundamentally one, for the
whole series belongs to one system, as much almost as the parts
of an animal to the one body ; and the relations of life to light
and heat, and to the atmosphere, have ever been the same as now.
The laws of the existing world, if perfectly known, are, consequently, a key
to the past history. But this perfect knowledge implies a complete comprehen¬
sion of nature in all her departments,—the departments of chemistry, physics,
mechanics, physical geography, and each of the natural sciences. Thus fur¬
nished, we may scan the rocks with reference to the past ages, and feel confident
that the truth will declare itself to the truth-loving mind.
As this extensive range of learning is not within the grasp of a single person,
special departments have been carried forward by different individuals, each in
his own line of research; for Geology as it stands is the combined result of
the labors of many workers. But the system is now so far perfected that the
ordinary mind may readily understand the great principles of the science, and
comprehend the unity of plan in the earth's genesis.
SUBDIVISIONS OF GEOLOGY.
10. (1.) Like a plant or animal, the earth has its systematic external
form and features, which should be reviewed.
(2.) Next, there are the constituents of the structure to be considered:
—first, their nature ; secondly, their general arrangement.
(3.) Next, the successive stages in the formation of the structure,
and the concurrent steps in the progress of life, through past
time.
(4.) Next, the general plan or laws of progress in the earth and
its life.
(5.) Finally, there are the active forces and mechanical agencies
which were the means of physical progress,—spreading out and
consolidating strata, raising mountains, ejecting lavas, wearing out
valleys, bearing the material of the heights to the plains and
oceans, enlarging the oceans, destroying life, and performing an
efficient part in evolving the earth's structure and features.
These topics lead to the following subdivisions of the science :—
" I. Physiographic Geology,—a general survey of the earth's sur¬
face-features.
8
INTRODUCTION.
II. Lithological Geology,—a description of the rock-material
of the globe, its elements, rocks, and arrangement.
III. Historical Geology,—an account of the rocks in the order
of their formation and the contemporaneous events in geological
history, including both stratigraphical and palasontological geology;
and closing with a review of the system or laws of progress in the
globe and its kingdoms of life.
IV. Dynamical Geology,—an account of the agencies or forces
that have produced geological changes, and of the laws and
methods of their action.
PART I.
PHYSIOGRAPHIC GEOLOGY.
11. The systematic arrangement in the earth's features is every
way as marked as that of any organic species; and this system
over the exterior is an expression of the laws of structure beneath.
The oceanic depressions or basins, with their ranges of islands, and
the continental plains and elevations, all in orderly plan, are the
ultimate results of the whole line of progress of the earth; and, by
their very comprehensiveness as the earth's great feature-marks,
they indicate the profoundest and most comprehensive movements
in the forming sphere, just as the exterior configuration of an
animal indicates its interior history. This subject is therefore an
important one to the geologist, although its facts come also within
the domain of physical geography. They lie at the top in geology
as its last results, and, thus situated, they constitute necessarily
the arena of the physical geographer.
The following are the divisions in this department:—
1. The earth's general contour and surface-subdivisions.
2. System in the reliefs or surface-forms of the continental lands.
3. System in the courses of the earth's feature-lines.
These topics are followed by a brief review of,—
4. The system of oceanic movements and temperature.
5. The system of atmospheric movements and temperature.
6. The general law for the distribution of forest-regions, prairies,
and deserts.
1. THE EARTH'S GENERAL CONTOUR AND SURFACE-
SUBDIVISIONS.
12. The subjects under this head are—the earth's form ; the
distribution of land and water ; the depth and true outlines of the
9
10
PHYSIOGRAPHIC GEOLOGY.
oceanic depression ; the subdivision of the land into continents ;
the height and kinds of surface of the continents.
13. (1.) Spheroidal form.—The earth has the form of a sphere
with flattened poles, the distance from the centre to the pole being
about l-300th (accurately, 3^2.4) shorter than from the centre to
the equator. The earth's equatorial radius being 3963 miles, the
polar is about 13] miles less (exactly 13.2405 miles).
This is a fact of prime importance in geology, and an appropriate introduction
to the science, inasmuch as it is the most obvious proof that the earth has a
history, or has been in course of progress under secondary causes; for this flat¬
tening is in amount just that which the revolution at its actual rate would pro¬
duce in a liquid globe having the she and density of the earth.
14. (2.) General subdivisions of the surface.—Proportion of
Land and Water.—In the surface of the sphere there are about 8
parts of water to 3 of dry land, or, more exactly, 275 to 100 = 5'2: 32.
The proportion of land north of the equator is nearly three times as
great as that south. The zone containing the largest proportion
of land is tire north-temperate, the area equalling that of the
water ; while it is only one-third that of the water in the torrid
zone, and hardly one-tenth (2-21ths) in the south-temperate.
Out of the 197,000,000 of square miles which makeup the entire surface of the
globe, 144,500,900 are water, and 52,500,000 land. In the northern hemisphere
the land covers 3S,900,000 square miles, in the southern 13,600,000 square miles.
15. Land in one hemisphere.—If a globe be cut through the centre
by a plane intersecting the meridian of 175° E. at the parallel
of 40° N., one of the hemispheres thus made, the northern, will
Fig. 1.
contain nearly all the land of the globe, and the other be almost
wholly water. The annexed map represents the two hemispheres.
GENERAL FEATURES OF THE EARTH.
11
The pole of the land-liemisphere in this map is in the western
half of the British Channel; and if this part, on a common globe,
be placed in the zenith, under the brass meridian, the horizon-
circle will then mark the line of division between the two hemi¬
spheres. The portions of land in the water-hemisphere are the
extremity of South America below 25° S., and Australia, together
with the islands of the East Indies, Pacific, and the Antarctic.
London and Paris are situated very near the centre of the land-
hemisphere.
16. General arrangement of the Oceans and ContinentsA—Oceans and
continents are the grander divisions of the earth's surface. But,
while the continents are separate areas, the oceans occupy one
continuous basin or channel. The waters surround the Antarctic
and stretch north in three prolongations,—the Atlantic, the Pacific,
and the Indian Oceans. The land is gathered about the Arctic, and
reaches south in two great continental masses, the occidental and
oriental; but the latter, through Africa and Australia, has two
southern prolongations, making in all three, corresponding to the
three oceans. Thus the continents and oceans interlock, the former
narrowing southward, the latter northward.
The Atlantic is the narrow ocean, its average breadth being 2800
miles. The Pacific is the broad ocean, being 6000 miles across, or
more than twice the breadth of the Atlantic. The Occident, or
America, is the narrow continent, about 2200 miles in average
breadth; the orient, the broad continent, 6000 miles. Each con¬
tinent has, therefore, as regards size, its representative ocean. This
great difference of magnitude is an important fact in its bearing on
the earth's geological history. The Pacific Ocean, reckoning only
to 62° S., has an area of 62,000,000 square miles, or nine and a
half millions beyond the area of all the continents and islands.
* In illustration of this part of the work, the reader is referred to the map at
the close of the volume. It is a Mercator's chart of the world, which, while it
exaggerates the polar regions, has the great advantage of giving correctly all
courses, that is, the bearings of places and coasts. The trends of lines (" trend"
means merely course or bearing) admit, therefore, of direct comparison upon
such a chart. It is important in addition that the globe should be carefully
studied in connection, in order to correct misapprehensions as to distances in
the higher latitudes, and appreciate the convergences between lines that have
the same compass-course.
The low lands of the continents on this chart, or those below 800 feet in ele¬
vation above the sea, arc distinguished from the higher lands and plateaus by a
lighter shading, and the axes of the mountain-ranges are indicated by black
lines. The oceans are crossed by isothermal lines, which are explained beyond.
12
PHYSIOGRAPHIC GEOLOGY.
17. (3.) Oceanic depression.—(a.) Outline.—The oceanic depres¬
sion is a vast sunken area, varying in depth from 1000 or less to,
probably, 50,000 feet.
The true outline of the depression is not necessarily identical
with the present line of coast. About the continents there is often
a region of shallow depths which is only the submerged border of
the continent. On the North American coast off New Jersey this
submerged border extends out for 80 miles, with a depth, at this
distance, of only 600 feet; and from this line the ocean-basin dips
off at a steep angle. The true outline of the basin on this and
other coasts is shown by the dotted line on the chart. The slope
for the 80 miles is only 1 foot in 700.
Great Britain is, on the same principle, a part of the European continent: the
separating waters are under 600 feet in depth; and a large part of the German
Ocean is only 93 feet. The true oceanic outline extends from Southern Norway
around by the north of Scotland and southward into the Bay of Biscay. (See
the dotted line on the chart.) In a similar manner, the East India Islands,
down to a line running by the north of New Guinea and Timor, are a part of
Asia, the depth of the seas intermediate seldom exceeding 300 feet; while south
of the line mentioned the islands are but fragments of Australia, the water being
no deeper than over the submerged Asiatic plateau.*
(b.) Depth of the Ocean.—The depth of the ocean in its different
parts has not been ascertained. Some deep soundings have been
made, and a few of them claim to have reached to a depth of
twenty-five to forty-five thousand feet; but the methods of sound¬
ing employed have been shown to be unsatisfactory, and the results,
therefore, are valueless.! Across from Ireland to Newfoundland,
the depth has been found to vary between 10,000 and 15,000 feet.
The Gulf of Mexico is known to be from 4000 to 5000 feet in depth.
According to calculations on the data furnished by an earthquake-
wave which, in 1855, crossed from Simoda, in Japan, to San Fran¬
cisco, the ocean in that line has an average depth of about 13,000
feet. The depth in the northern part of the Pacific and Atlantic
may be, therefore, nearly the same. South of this in each it is pro¬
bably very much greater.
The mean depth of the oceanic depression is, by estimate,
between 15,000 and 20,000 feet.
(c.) Character of the Oceanic Basins.—To appreciate the oceanic basins
* Earl, Jour. Indian Arch. [2], ii. 278, and Am. Jour. Sci. [2], xxv. 442.
! Some of the results are as follow : — A sounding by Capt. Ross, 900 m. SAV.
of St. Helena, 27,600 feet without bottom ; by Capt. Denham, in 36° 49' S., 37°
6' W., 46,236 feet (7706 fathoms) found bottom.
GENERAL FEATURES OF THE EARTH.
13
we must conceive of the earth without its water,—-the depressed
areas, thousands of miles across, sunk ten to perhaps fifty thousand
feet below the bordering continental regions, and covering five-
eighths of the whole surface. The continents, in such a condition,
would stand as elevated plateaus encircled by one great uneven
basin. If the earth had been left thus with but shallow lakes
about the bottom, there would have been an ascent of five miles or
more from the Atlantic vale to the lower part of the continental
plateau, and one to five miles beyond this to scale the summits of
the loftier mountains of the globe. The continents would have been
wholly in the regions of the upper cold, all alpine and barren. This
uneven surface of the Atlantic and Pacific has been levelled oft1 to a
plain by the waters of the ocean, the heights of the world reduced
from ten or fifteen miles to five, and the intolerable climates of such
extremes of surface reduced to a genial condition, rendering nearly
the whole land habitable, and giving moisture for clouds, rivers,
and plants ; and, by the same means, distant points have been
bound together by a common highway into one arena of history.
18. (4.) General view of the land.— (a.) Position of the land.
—The land of the globe has been stated to lie with its mass to the
north, about the Arctic, and to narrow as it extends southward
into the waters of the Southern hemisphere. The mean southern
limit of the continentablands is the parallel of 45°, or just half-way
from the equator to the south pole.
South America reaches only to 56° S. (Cape Horn being in 55° 58'), which is
the latitude of Edinburgh or northern Labrador; Africa to 34° 51' (Cape of
Good Hope), nearly the latitude of the southern boundary of Tennessee, and 00
miles nearer the equator than Gibraltar; Tasmania (Van Diemen's Land) to
431° S., nearly the latitude of Boston and northern Portugal.
19. if>.) Distribution.—The independent continental areas are three
in number :—America, one ; Europe, Asia, and Africa, a second;
Australia, the third. Through the East India Islands Australia is
approximately connected with Asia, nearly as South America with
North America through the West Indies; and, regarding it as
thus united, the great masses of land will be but two:—The Ame¬
rican, or Occidental, and Europe, Asia, Africa, and Australia, or the
Oriental.
These great masses of land are divided across from east to west
by seas or archipelagoes. The West Indies, Mediterranean, Red
Sea, and the East Indies, with the connecting oceans, make a nearly
complete band of water around the globe, as Professor Guyot ob¬
serves, subdividing the Occident and Orient into north and south
divisions. Cutting across 37 miles at the Straits of Darien, where
14
PHYSIOGRAPHIC GEOLOGY.
at the lowest pass the greatest height above mean tide-level does
not exceed 500 feet, and through 70 miles at the Isthmus of Suez,
where the summit-level is only 40 feet above the sea, the girth of
water would be unbroken.
America is thus divided into North and South America. The
oriental lands have one great area on the north, comprising Europe
and Asia combined, and on the south (1) Africa, separated from
Europe by the Mediterranean, and (2) Australia, separated from
Asia by the East India seas. Thus the narrow Occident has one
southern prolongation, and the wide Orient two. It is to be noted
that the East and West Indies are very similar in form and posi¬
tion (see chart); and also that South America is situated with
reference to North America very nearly as Australia is to Asia.
The Orient thus corresponds to two Occidents in which the
northern areas coalesce,—Europe and Africa one, Asia and Aus¬
tralia the other; so that there are really three doublets in the
system of continental lands. Moreover, Europe and Asia have
a semi-marine region between them ; for the Caspian and Aral are
salt seas, and they lie in a depression of the continent of great
extent,—the Aral being near the level of the ocean, and the Cas¬
pian 80 to 100 feet below it.
The islands adjoining the continents are properly portions of
the continental regions. Besides the examples mentioned on page
12, Japan and the ranges of islands of eastern Asia are strictly a
part of Asia, for they conform in direction to the Asiatic system
of heights, and are united to the main by shallow waters. Van¬
couver's Island and others north are similarly a part of North
America; Chiloe, and the islands south to Cape Horn, a part of
South America; and so in other cases.
The body of the continent of Africa lies in those latitudes which
are almost wholly water in the American section, its western ex¬
pansion corresponding to the indentation of the Caribbean Sea and
the Gulf of Mexico.
20. (c.) Oceanic islands.—The islands of mid-ocean are in ranges,
and are properly the summits of submerged mountain-chains. The
Atlantic and Indian Oceans are mostly free from them. The Pacific
contains about 675, which have, however, an aggregate area of only
80,000 square miles. Excluding New Caledonia and some other
large islands in its southeastern part, the remaining 600 islands
have an area of but 40,000 square miles, or less than that of New
York State. The islands stretch oft" in a train from the Asiatic
coast through the tropics in an east south-east direction, and, soon
crossing the equator, lie mostly in the southern tropic. The train
GENERAL FEATURES OF THE EARTH.
15
extends to Easter Island and Sala-y-Gomez, in longitudes 110° and
105° W., a distance of 8000 miles. The greatest depth of the ocean
should be looked for outside of the limits of this train.
21. (d.) Mean elevation.—The mean Height of the continents above
the sea, exclusive of Australia and Africa, according to an estimate
by Humboldt, is about 1000 feet : and this is probably not far from
the truth for all the land of the globe. As the area of the ocean and
land is as 8 to 3, if all this land above the present water-level were
transferred into the oceans, it would fill them 3-8ths of 1000 or 375
feet; and, taking the average depth at 15,000 feet, it would take 40
times this amount to fill the oceanic depressions.
The mean height of the several continents has been stated as
follows:—Europe, 070 feet; Asia, 1150; North America, 748; South *
America, 1132; all America, 930; Europe and Asia, 1010; Africa,
probably about 1000 feet; and Australia, perhaps 500. It has been
estimated that the material of the Pyrenees spread over Europe
would raise the surface only Gfeet; and the Alps, though four times
larger in area, only 22 feet.
The extremes of level in the land, as far as now known, are, 1300
feet below the level of the ocean, at the Dead Sea, and 29,000 feet
above it, in Mount Everest of the Himalayas. Both of these points
occur on the continent of Asia, which has also its great depressed
Caspian area (p. 19). On no other continent is there a region
below the ocean's level.
22. (5.) Subdivisions of the surface, and character of its re¬
liefs.—The surfaces of continents are conveniently divided into
(1) low lands; (2) plateaus, or elevated table-lands : (3) mountains.
The limits between these subdivisions are quite indefinite, and are
to be determined from a general survey of a country rather than
from any specific definition.
The low lands include the extended plains or country lying not
far above tide-level. In general they are less than 1000 feet above
the sea; but they are marked off rather by their contrast with
higher lands of the mountain-regions than by any precise altitude.
The Mississippi Valley of the great interior region of the North
American continent is an example; also the plains of the Amazon :
the pampas of La Plata ; the lower lands of Europe and Asia. The
surface is usually undulating, and often hilly. Frequently the
surface rises so gradually into the bordering mountain-declivities
that the limit is altogether an arbitrary line, as in the case of the
Mississippi plains and the Rocky Mountain slope.
A mountain is either an isolated peak,—as Mount Washington,
Mount Blanc, Mount Etna,—or a ridge. For a long ridge or range.
16
PHYSIOGRAPHIC GEOLOGY.
the plural is used, as the Green Mountains, the Ozark Mountains. A
mountain-chain is a system of ridges with the included high land.
A sierra is, in Spanish, a ridge of mountains, and alludes to the saw-like out¬
line. A corclillera, in South America, is a mountain-chain. Mauna, as in
Mauna Loa, of Hawaii, signifies mount.
An elevated plateau is an extensive elevated region of flat or hilly
surface, such as often occurs in mountainous regions. Any exten¬
sive range of country that is over a thousand feet in altitude would
be called a plateau. It may lie along the course of a mountain-
chain, or occupy a wide region between distant chains. The
"Gi'eat Basin" between the Salt Lake and the Siei'ra Nevada is a
plateau of the Rocky Mountain chain, 4000 to 5000 feet in eleva¬
tion: the Salt Lake lies in its northeast corner, 4200 feet above the
sea. The plateau or table-land of Thibet lies between the Himalayas
and the Kuen-Luen Mountains next to the north, and is 11,500
to 13,000 feet in altitude; and the plateau of Mongolia (Desert of
Gobi) occupies a vast region farther north, having a mean eleva¬
tion of 4000 feet. The State of New York is an elevated plateau,
1500 to 1700 feet in altitude north of the Mohawk (an east-and-
west valley), and 2000 to 2500 feet south of this river: it lies in the
course of the Appalachian Mountains.
Plateaus often have their mountain-ridges, like low lands.
23. Mountains.—The form of an isolated mowrito'n-peak depends
on its general slopes ; that of a ridge, on (1) its slopes, (2) the out¬
line of the crest, and (3) the coui'se or arrangement of the consecu¬
tive parts of the ridge; that of a chain,ton all these points, and in
addition (4) the order or arrangement of the ridges in the chain.
(a.) Slopes of mountains.—The mountain-mass.—The slopes of the lai'ger
mountains and mountain-chains are generally very gradual. Some
of the largest volcanoes of the globe, as Etna and Mount Loa
(Hawaii), have a slope of only G to 8 degrees. The mountains are
low cones having a base of 50 miles or more.
The Rocky Mountains, Andes, and Appalachians are three
examples of mountain-chains. The average eastern slope of the
Rocky Mountains seldom exceeds 10 feet in a mile, which is about
1 foot in 500, equal to an angle of only 7 minutes. On the west
the average slope is but little less gradual. The rise on the east
continues for 600 miles, and the fall on the other side for 400 to
500 miles ; the passes at the summit have a height of 6000 to 10,000
feet; and above them, as well as over different parts of the slopes
(especially on the west), there are ridges carrying the altitude to
12,000 or 14,000 feet. The mountain-mass, therefore, is not a nar¬
row barrier between the east and west, as might be inferred from
GENERAL FEATURES OF THE EARTH.
the ordinary maps, but a vast yet gentle swell Fig.
of the surface, having a base 1000 miles in m o
breadth, and the slopes diversified with va- ~
rious mountain-ridges or spreading out in 5 y ;
plateaus at different levels.
The annexed section (Fig. 2) of the Rocky Z ^ *
Mountains along the parallels 41° and 42°, from | g y
Council Bluff, on the east, to Benicia, in Cali- g §
fornia, illustrates this feature, although an 3. J -•
exaggerated representation of the slopes,—the 1 1, »
height being seventy times too great for the .P f §
length. it %
t
?
In the Andes the eastern slope is about GO
feet in a mile, and the western 100 to 150 feet; - _■ „
the passes are at heights from 12,500 to 10,160 V = p-
feet, and the highest peak—Sorata in Bolivia— = (L &
25,290 feet. The slope is much more rapid
than in the Rocky Mountains. But there is
the same kind of mountain-mass variously T § |
diversified with ridges and plateaus. The ex- A 3 ^
istence of the great mountain-mass and its « f.
plateaus is directly connected with the exist- 4 2 ^
ence of the main ridges. But it will be shown k "
in another place that the ridges may have % 3 |
existed long before the mass had its present 3 8 S
elevation above the sea. L 3 f
In the Appalachians—which include all the 3 5-
mountains from Georgia to the Gulf of St. 3 5 y
Lawrence—the mountain-mass is very much : ^
smaller and the component ridges are rela- L ^
tively more distinct and numerous, and still 5 5 o
the general features are 011 the same principle.
The greatest heights—those of North Carolina
A
—are between 0000 and 0800 feet. fi k, to
The Rocky Mountains, Andes, and Appa- it jjf
lachians represent the three types of chains • A. A 3
(1) the broad and lofty plateau type; (2) the
'£
narrow and lofty ridgy type, of which the s % 3
Himalayas are another example : (3) the broad I' « g
and many-folded type, of which the Juras are §
another example. =f A o
Illvstrations.—It is common to err in estimating § g> "o
the angle of a slope. To the eyes of most travellers, a j? it «
18 PHYSIOGRAPHIC GEOLOGY.
slope of 60° appears to be as steep as 80°, and one of 30° to be at least 50°. In
a front view of a declivity it is not possible to judge rightly. A profile view
should always be obtained and carefully observed before registering an opinion.
Fig. 3.
In fig. 3 the bluff front facing the left would be ordinarily called a vertical
precipice, while its angle of slope is actually about 65° ; and the talus of broken
stones at its base would seem at first sight to be 60°, when really 40°.
Fig. 4.
T
13 I)
Fig. 5.
A.
Fig. 4 represents a section of a volcanic mountain 3° in angle; 5, another, of
7°,—the average slope and form of Mount Kea, Hawaii; 6, the same slope with
Fig. 7. Fig. 8. Fig. 9.
the top rounded, as in Mount Loa; 7, a slope of 15°; 8, Jorullo, in Mexico,
which has one side 27° and the other 34°, as measured by N. S. Manross; 9, a
slope of 40°,—the steepest of volcanic cones. The lofty volcanoes of the Andes
are not steeper than in number 8, although frequently so pictured.
With a clinometer (see fig. 102) held between the eye and the mountain,
the an<*le of slope may be approximately measured. When no instrument is at
hand, it is easy to estimate with the eye the number of times a vertical as A B
in fig. 5 is contained in the semi-base B C ; and, this being ascertained, the angle
of slope may be easily calculated. The ratio 1 : 1 corresponds to the angle of
45° ; 1 : 2 to 33° 41J'; 1:3 to 26° 34'; 1 : 4 to 18° 26'; 1 : 5 to 11° 184'; 1:6 to
9° 28'; 1:7 to 8° 8'; 1:8 to 7° 74'; 1 : 9 to 6° 204'; 1 : 10 to 5° 42*'; 1 : 12 to
4° 46'; 1:15 to 3° 49'; 1 : 20 to 2° 52'. The inclinations corresponding to
several of these ratios are represented in the following cut. Fig. (10.)
GENERAL FEATURES OF THE EARTII.
19
24. (b.) Composition of mountain-chains.—(1.) Mountain-chains have
been stated to include several mountain-ridges; and even the
ridges often consist of subordinate
parts similar in arrangement. In
the great chain of western North
America,—the Rocky Mountains,
—about the summit there are, in
general, two prominent ranges;
then, west of the summit, within
100 to 150 miles of the coast, there
is the Washington Range, includ¬
ing the Cascade of Oregon and the
Sierra Nevada of California, each
with peaks over 12,000 feet in
height; between this range and
parts several ridges more or less important; and between it and
the coast other ridges make up what has been called the Coast
Range. The Appalachians also, although but a small chain, con¬
sist of a series of nearly parallel ridges. In Virginia there are,
beginning to the eastward, the Blue Ridge, the Shenandoah Ridge,
and the Alleghany, besides others intermediate.
(2.) The ridges of a chain vary along its course. After continu¬
ing for a distance, they may gradually become lower and disap¬
pear ; and while one is disappearing another may rise to the right
or left; or the mountain may for scores of leagues be only a pla¬
teau without a high ridge, and then new ranges of elevations
appear. The Rocky Mountains exemplify well this common cha¬
racteristic, as is seen on any of the recent maps. The Sierra Ne¬
vada dies out where the Cascade Range begins; and each has
minor examples of the same principle. The Andes are like the
Rocky Mountains; only the parts are pressed into narrower com¬
pass, and the crest-ranges are hence continuous for longer dis¬
tances. The Appalachian ridges are rising and sinking along the
PIIYSIOGltAl'II I<1 GEOLUUY.
course of the chain. The high land of the southwest terminates
in Xow York ; and just cast stands the separate, line of the Green
Mountains : and still farther eastward,—east of the Connecticut,—
the range of the White Mountains.
The general idea of this composite structure is shown in tigs.
Fig. 17.
1 I to 10, where each series of lines represents a series of ridges
in a composite range. In fig. 11 the series is simple and straight :
GENERAL FEATURES OF THE EAR I'M.
in 12 it is still straight, but complex: in 13 tin parallel part* are
so arranged as still to make a straight composite range : while in
14 and 15 the succession forms a curve : and in l(i there are trans¬
verse ridges in a complex series. In ridges or ranges thus com¬
pounded, the component parts may lie distinct, or they may
so coalesce as not to be apparent.
These several conditions of uninterrupted and overlapping lines, constituting
straight and curving chains, are illustrated among the islands of the oceans,
the direction of coast-lines, and the courses of all the reliefs of the earth's sur¬
face, as is explained in the following pages. Figure 28 on page 35, representing
the positions of the Australasian islands from New Hebrides to Sumatra, finely
exhibits the system of structure.—also fig. 27. giving the courses and relative
positions of the central groups of the Pacific, and fig. 21), representing the
Azores in the Atlantic: for the courses of islands are the courses of mountain-
chains. The South Atlantic and North Atlantic are two overlapping lines
parallel in course, and on a still grander scale, one of them being much in
advance or to the westward of the other, and each several thousand miles
long.
The preceding map of the trap ridges of Connecticut, from Percival's Report,
presents the structure finely. The narrow bands running nearly north-and-
south represent the ridges : they are in many nearly parallel lines; each con¬
sists of subordinate parts ; and in several the parts lie in advancing or receding
series. The extent of the series is small compared with a mountain-chain :
and the ridges, few of which exceed 600 feet in height, are ejections through
fissures beneath. But the parallelism in structure is perfect. The curves in
some of the subordinate ridges have arisen from the fact that the fissures come
up through a tilted sandstone, and the ejected rock escaped partly direct from
the fissure and partly between the lifted strata of sandstone, and hence in a
direction different from that of the fissure, the two directions together making
the curve.
25. Solid dimensions of mom,fains.—The modes of calculating the
mass of a mountain are the same that are given in treatises on
mensuration. By a careful system of averaging, based on deter¬
minations of the slopes and altitudes, as far as practicable, the
mountain-mass is reduced to one or more cones, pyramids, or
prisms; and then the solid contents of the cones or pyramids are
obtained by multiplying the area of the base into one-third the
altitude; or, for a triangular prism lying on one of its sides, the
area of that side into half the length of a line drawn vertical to it
from the opposite edge.
20. Elevated Plateaus, or table-lands.—Some examples of these
plateaus have been mentioned (\ 22). The Llano Estacado
(staked plain) in New Mexico and Upper Texas, southeast of
Santa Fe, is another, of great extent, about 4500 feet in elevation.
The great Mexican plateau, in which the city of Mexico lies, has
22
PHYSIOGRAPHIC GEOLOGY.
about that city a height of 7482 feet, and slopes from this to 5000
on the east and 4000 on the west; and it stretches on north
beyond the Mexican territory, blending with the plateaus of New
Mexico. Above it rise many lofty volcanic cones, among which
Popocatepetl is 17,884 feet high, Orizaba 17,373 feet, and Istacci-
huatl 15,704.
The plateau of Quito, in the Andes, has a height of 10,000 feet,—Quito itself
9540 feet,; and around it are Cotopaxi, 18,775 feet, Chimborazo, 21,421, Pichin-
eha, 15,924, Cayainbe, 19,535. The plateau of Bolivia is at an elevation of
12,900 feet, with Lake Titicaca, 12,830 feet, and the city of Potosi at 13,330 feet:
and near are the volcanic peaks Illimani, 23,868 feet, Sorata, 25,290, Huayna
Potosi, 20,260. In Europe, Spain is for the most part a plateau about 2250 feet
in average elevation; Auvergne, in France, another, at about 1100 feet; Bavaria
another, at 1660 feet. Persia is a plateau varying in elevation between 3800
and 4500 feet, with high ridges in many parts. The Abyssinian plateau, in
Africa, has an average elevation of more than 7000 feet; the region of Sahara,
about 1500 ; that of the interior of Africa south of the equator, about 2500 feet.
27. River-Systems.—Plateaus and mountains are the sources of
rivers. They pour the waters along many channels into the basin
or low country towards which they slope; and the channels, as
they continue on, unite into larger channels, and finally into one or
more trunks which bear the waters to the sea. The basin and its
surrounding slopes make up a river-system. The extent of such
a region will vary with the position of the mountains and ocean.
It may cover but a few hundred square miles, like the river-regions
on a mountainous coast, or it may stretch over the larger part of
a continent.
The interior of the United States belongs to one river-system,—
that of the Mississippi; its tributary streams rise on the west
among the snows of the Rocky Mountains, on the north in the central
plateau of the continent, west of Lake Superior, near lat. 47° and
beyond long. 93°-96°, 1680 feet in elevation, and on the east in the
Appalachians, from western New York to Alabama. Besides the
Mississippi, there are other rivers rising in the Rocky Mountains
and flowing into the Gulf of Mexico ; and, in a comprehensive
view of the continent, these belong to the same great river-system.
The St. Lawrence represents another great river-region in North
America,—a region which commences in the head-waters of Lake
Superior about the same central plateau of the continent that
gives rise to the Mississippi, and embraces the great lakes with
their tributaries and the rivers of Canada, and flows finally north¬
eastward into the Atlantic, following thus a northeast slope of the
continent. North of Lake Superior and the head-waters of the
Mississippi, as far as the parallel of 55°, there are other streams,
GENERAL FEATURES OF THE EARTH.
23
which also flow northeastward, deriving some waters from the
Rocky Mountains through the Saskatchewan, and reaching the
ocean through Hudson's Bay. Winnipeg Lake is here included.
These belong with the St. Lawrence, the whole together consti¬
tuting a second continental river-system.
The Mackenzie is the central trunk of still another river-system,
—the northern. Starting from near the parallel of 55°, it takes
in the slopes of the Rocky Mountains adjoining, and much of the
northern portion of the continent. Athabasca, Slave, and Bear
Lakes lie in this district.
These are examples from among the river-systems of the
world.
Lakes.—Lakes occupy depressions in the earth's surface which,
from their depths or positions, are not completely drained by the
existing streams, nor kept dry by the heat and drought of the
climate. They occur (1) over the interior of table-lands, as about
the head-waters of the Mississippi; (2) along the depressions
between the great slopes of a continent, as the line of lakes in
British North America running northwest from Lake Superior;
(3) in confined areas among the ridges of mountains. The natural
forms of continents—that is, their having high borders—-tend to
occasion the existence of lakes in their interior.
If a lake has no outlet to the ocean, its water is usually salt;
and any plain or plateau whose streams dry up without communi¬
cating with the sea contains salt basins and efflorescences. The
Caspian, Aral, and Dead Sea are some of the salt lakes of Asia;
and the Great Salt Lake of the Rocky Mountains is a noted one
on this continent. Many parts of the Rocky Mountains, the
Great Basin of the West, the Pampas of South America, and all
the desert regions of the globe, afford saline efflorescences.
2. SYSTEM IN THE RELIEFS OR SURFACE-FORMS OF THE
CONTINENTS.
28. Law of the system.—The mountains, plateaus, low lands,
and river-regions are the elements in the arrangement of which
the system in the surface-form of the continents is exhibited. The
law at the basis of the system depends on a relation between the
continents and their bordering oceans, and is as follows:—
First. The continents have in general elevated mountain-borders
and a low or basin-like interior.
Secondly. The highest border faces the larger ocean.
A survey of the continents in succession with reference to this
law will exhibit both the unity of system among them and the
'--I PHYSIOGRAPHIC (iEOROGY.
peculiarities of each dependent on their diii'erent relations to tin*
oceans.
(1.) America.—The two Americas are alike in lying between
the Atlantic and the Pacific: moreover, South America is set so
far to the east of North America (being east of the meridian of
Niagara Falls) that each has an almost entire ocean-contour.
Moreover, each is triangular in outline, with the widest part, or
head, to the north.
North America, in accordance with the law, has on the Pacific
side—the side of the great ocean—the Rocky Mountains, on the
Atlantic side the low Appalachians, and between the two there is
the great plain of the interior. This is seen in the annexed
section (fig. 18) from west to east: on the west, the Rocky Moun-
Fig. IS.
a /, C d E
tains, with the double crest, at L, the Washington Range at a.
between a, h the Great Basin, at d the Appalachians, c the Mis¬
sissippi, and between d and b a section of the Mississippi river-
system.
The Cascade and Nevada Ranges are even more lofty in some of their sum¬
mits than the crest-ridges of the Rocky chain. In the former there is a line
of snowy cones from 12.000 to 16,000 or 18,000 feet in elevation, including
Mount Raker, near Puget's Sound, and, to the south of this, Mount St. Helen's.
Mount Adams, and Mount Rainier, north of the Columbia, and, south. Mount
Hood, Mount Pitt, Mount Jefferson, and the Shasta Peak,—the last on the border
of California. Still nearer the sea there is what is called the Coast Range, con¬
sisting of lower elevations. Between the two lie the valley of the Sacramento
and Joaquin, in California, and that of the Willamette, in Oregon.
The Appalachians, on the cast, reach an extreme height of but
1)700 feet, and are in general under 2500 feet.
To the north of North America lies the small Arctic Ocean,
much encumbered with land : and, correspondingly, there is no
distinct mountain-chain facing the ocean. The mountains of
Greenland are an independent system, pertaining to that semi-
continent by itself.
The characteristics of the interior plain of the continent are
well displayed in its river-systems: the great Mississippi system
turned to the south, and making its exit into the Gulf of Mexico
between the approaching extremities of the eastern and western
mountain-ranges; the St. Lawrence sloping off northeastward :
GENERAL FEATURES OF THE EARTH.
25
the Mackenzie, to the northward; the central area of the plain
dividing the three systems being only about 1700 feet above the
ocean,—a less elevation than about the head-waters of the Ohio in
the State of New York.
South America, like North America, has its great western range
of mountains, and its smaller eastern (fig. 19 ); and the Brazilian
Fig. 19.
line (b) is closely parallel to that of the Appalachians. As the
Andes («) face the South Pacific, a wider and probably much
deeper ocean than the North Pacific, so they are more than twice
the height of the Rocky Mountains, and, moreover, they rise more
abruptly from the ocean, with narrow shore-plains.
Unlike North America, South America has a broad ocean on the
north,—the North Atlantic in its longest diameter ; and, accord¬
ingly, this northern coast has its mountain-chain reaching along
through Venezuela and Guiana.
The drainage of South America, as observed by Professor Guyot,
is closely parallel with that of North America. There are,first, a
southern,—the La Plata,—reaching the Atlantic towards the south,
between the converging east-and-west chains, like the Mississippi;
second, an eastern system,—that of the Amazon,—corresponding to
the St. Lawrence, reaching the same ocean just north of the
eastern mountain-border; and, third, a northern system,—that of the
Orinoco,—draining the slopes or mountains north of the Amazon
system. The two Americas are thus singularly alike in system of
structure: they are built on one model.
The relation of the oceans to the mountain-borders is so exact
that the rule-of-three form of statement cannot be far from the
truth. As the size of the Appalachians to the size of the Atlantic, so is tin-
size of the Rock;/ chain to the size of the Pacific. Also, A.v the heii/ht of the
Rock;/ chain to the extent of the North Pacific, so are the he'ajht ami boldness
of the Andes to the extent of the South Pacific.
30. (2.) Europe and Asia.—The land covered by Europe and
Asia is a single area or continent, only partially double in its
nature (§ 19). Unlike either of the Americas, it lies east-and-
west, with an extensive ocean facing Asia on the south : and its
great feature-lines are in a large degree east-and-west. The Arctic
is on the north; the North Atlantic is on the west; the North
26
PHYSIOGRAPHIC GEOLOGY.
Pacific on the east; Africa and the Indian Ocean are on the south.
The Atlantic is the smallest ocean ; the North Pacific next,—for its
average depth is probably not over 13,000 feet (p. 12), and it is
much encumbered by islands to the west-of-south ; the Indian
Ocean next,—for it is full 5000 miles wide in front of the Asiatic
coast, and singularly free from islands. The boundary is a complex
one, and the land between the Atlantic and Pacific over 6000
miles broad.
On the side of the small North Atlantic there are the moun¬
tains of Norway and the British Isles, the former having a mean
height of 4000 feet. On the Pacific side there are loftier moun¬
tains, extending in several ranges from the far north to southern
China,—the Stanovoi, Jablonoi, and the Khingan Ranges ; and off
the coast there is still another series of ranges, now partly sub¬
merged,—viz., those of Japan and other linear groups of islands.
These stand in front of the interior chain, very much as the
Cascade Range and Sierra Nevada of the Pacific border of America
are in advance of the summit-ridges of the Rocky Mountains,
and both are alike in being partly volcanic, with cones of great
altitude.
Facing the still greater Indian Ocean, and looking southward,
stand the Himalayas,—the loftiest of mountains,—called the Hima¬
layas as far as Cashmere, and from there, where a new sweep in
the curve begins, the Hindoo Cush,—the whole over 2000 miles in
length: not so long, it is true, as the Andes, but continued as
far as the ocean in front continues. The mean height of the
Himalayas has been estimated at 16,000 feet; over forty of the
peaks surpass Chimborazo. The Kuen-Luen Mountains, to the
north of the Himalayas, make another crest to the great chain,
with Thibet between the two. Going westward, the mountains
decline, though there are still ridges of great elevation.
On the north there are the great Siberian plains, backed by the
Altai, about half the Himalayas in height. The Altai thus have
Fig. 20.
the same relation to the Himalayas as the Appalachians to the
Rocky Mountains, or the Brazilian Mountains to the Andes, yet
general features of the earth.
27
with a striking difference in the immense shore-plain between
them and the sea.
The sketch (fig. 20) presents the general features to the eye.
At a, there is the elevated land of India ; between a and b, the low
river-plain at the base of the Himalayas ; at b, the Himalayas ; b to
<*, Plains of Thibet; c, the Kuen-Luen ridge; ctod, Plains of Mongolia
and Desert of Gobi; at d, the Altai; d to n, the Siberian plains.
The interior region of the continent in its eastern half is the
plateau of Gobi and Mongolia, which, at 4000 feet, is low compared
with the mountains in front and rear. More to the westward the
region c, d becomes intersected by the lofty Thian-chan Range.
Still farther westward the surface declines into the great depression
occupied by the Caspian and Aral, part of which is below tide-level
(I 19).
The interior drainage-system for Asia is without outlet. The
waters are shut up within the great basin, the Caspian and Aral
being the seas which receive those waters that are not lost in the
plains. The Volga and other streams, from a region of a million
of square miles, flow into the Caspian.
The Urals stand as a partial barrier between Asia and Europe,
parallel nearly with the mountains of Norway.
Europe has its separate system of elevations and interior plains;
but it is not necessary to dwell on it here.
The great continental mass accords with the law stated :—high
borders proportioned in the case of each to the extent of the bor¬
dering oceans, and a general basin-form.
31. (3.) Africa.—Africa has the Atlantic on the west, the larger
Indian Ocean on the east, with Europe and the Mediterranean on
the north, and the South Atlantic and Southern Ocean on the
south. Its system of structure has been well explained by Pro¬
fessor Guyot. As lie has stated, the northern half has the east-
and-west position of Asia, and the southern the north-and-south
of America; and its reliefs corresjiond with this structure. The
Guinea coast belonging to the northern half projects west in front
of the South Atlantic, and is faced by the east-and-west Kong
Range; and opposite, on the Mediterranean, there are the Atlas
Mountains, one peak of which is 11,000 feet high,—although the
ridges are generally much lower. The two thus oppose one
another, like the Himalayas and Altai. The southern half of the
continent has a border mountain-range the most of the way along
the west and south. On the latter, which has a length of 700
miles, there are three or four parallel ridges, and some of the
peaks are 4000 to 7000 feet high. Up the eastern coast there is
28
PHYSIOGRAPHIC (IKOLOGY.
also a mountain-border, and higher than the western. By these
border-ranges the interior of Africa is mostly shut off from the sea:
—it is a shut-up continent, as Guyot calls it. The loftiest mountains
are in Abyssinia and Zanguebar, facing the Indian Ocean. Abys¬
sinia is, to a great extent, an elevated plateau, 0000 to 7000 feet in
height, with ridges reaching to 11,000 and 18,500 feet : and farther
south, in 3° 40/, stands the snowy Kilimanjaro, which, according
to report, is 20,000 feet high, and probably the source of the Kile.
The interior of the northern or east-and-west half consists of (1)
the Great Sahara region, a plateau of about 1500 feet elevation,
with its undulations and ridges : (2) an east-and-west depression
on the north, between Sahara and the border-mountains, nearly to
the ocean's level in some parts, and being the region of the muses;
(3) a partial east-and-west depression about the parallels 10° to
15° N., separating the Sahara plateau from the southern, and con¬
taining Lake Tchad, at an elevation of 800 feet. The interior of
the southern half is a plateau 2000 to 2500 feet in average height:
the great lake Uniamesi, south of the equator, between the meri¬
dians 25° and 35°, is stated by Livingstone to have its surface 2000
feet above the sea.
Fig. 21.
S <i I, C (1 e £ TS
The sections figs. 21 and 22 give a general idea of these features
Fig. 21 is a section from south to north (the heights necessarily
much exaggerated in proportion to the length): a. the southern
mountains ; I, the southern plateau : c. Lake Tchad depression :
d, Sahara plateau ; e, oases depression : f. mountains on the Medi¬
terranean, of which there are two or three parallel ranges. Fig. 22
Fig. 22.
represents the surface-outline from west to east through the
southern half of the continent. In all these sections all minor
details are omitted, in order to bring out clearly the system, or
continental model.
Africa has, therefore, the basin-form, but is a double basin; and
its highest mountains are on the side of the largest ocean, the
Indian. The height of the mountains adjoining the Mediter¬
ranean is the only exception to the relation to the oceans: and this
is small. Moreover, the position of the head of the continent
GENERAL FEATURES OF T1IE EARTH.
29
against the continent of Europe with only the Mediterranean
between, instead of an ocean, is a sufficient reason for the excep¬
tions. Africa has some resemblance to America, but America
turned about, with the most elevated border on the east instead of
the west.
32. (4.) Australia.—Australia conforms also to the continental
model. The highest mountains are on the side of the Pacific,—
the larger of its border-oceans. The Australian Alps, in New South
Wales, facing the southwest shores, have peaks 5000 to 0500 feet in
height. The range is continued northward in the Blue Mountains,
which are 3000 to 4000 feet high, with some more elevated summits,
and, beyond these, in ridges under other names, the whole range
being mostly between 2000 and 0000 feet in elevation. The interior
is regarded as a low, arid region.
The continents thus exemplify the law laid down, and not
merely as to high borders around a depressed interior,—a prin¬
ciple stated by many geographers,—but also as to the highest border
being on the side of the greatest ocean.* The continents, then, are
all built on one model, and in their structures and origin have a
relation to the oceans that is of fundamental importance.
It is owing to this law that America and Europe literally stand
facing one another, and pouring their waters and the treasures of
the soil into a common channel, the Atlantic. America has her
loftier mountains, not on the east, as a barrier to intercourse with
Europe, but off in the remote west, on the broad Pacific, where
they stand open to the moist easterly winds as well as those of
the west, to gather rains and snows, and make rivers and alluvial
plains for the continent; and the waters of all the great streams,
lakes, and seas make their way eastward to the narrow ocean that
divides the civilized world. Europe has her slopes, rivers, and
great seas opening into the same ocean; and even central Asia
has her most natural outlet westward to the Atlantic. Thus, under
this simple law, the civilized world is brought within one great
country, the centre of which is the Atlantic, uniting the land by a
convenient ferriage, and the .sA/r.v the slopes of the Rocky Moun¬
tains and Andes on the >r<v/, and the remote mountains of Mon¬
golia, India, and Abyssinia on the ra.vt.f
This subject affords an answer to the inquiry, What is a continent
as distinct from an island? ft is a body of land so large as to have
the typical basin-form,—that is, mountain-borders about a low inte-
First announced American Jour. Sci. [2], vols. iii. 31)8, iv. 92, 1847, and xxii.
35, 185(5. t See Guvot's Earth and Man.
30
PHYSIOGRAPHIC GEOLOGY.
rior. The mountain-borders of the continents vary from 500 to
1000 miles. Hence a continent cannot be less than a thousand
miles (twice five hundred) in width.
3. SYSTEM IN THE COURSES OF THE EARTH'S FEATURE-
LINES.
33. The system in the courses of the earth's outlines is exhibited
alike over the oceans and continents, and all parts of the earth are
thus drawn together into even a closer relation than appears in the
principle already explained.
The principles established by the facts are as follow: That (1)
two great systems of courses or trends prevail over the world, a north¬
western and & northeastern, transverse to one another; (2) that the islands
of the oceans, the outlines and reliefs of the continents, and the
oceanic basins themselves, alike exemplify these systems; (3) that
the mean or average directions of the two systems of trends are
northwest-by-west and northeast-by-north; (1) that there are wide
variations from these courses, but according to principle, and that
these variations are often along curving lines; (5) that, whatever
the variations, when the lines of the two systems meet, they meet
nearly at right angles or transversely to one another.
34. (1.) Islands of the Pacific Ocean.—The lines or ranges of
islands over the ocean are as regular and as long as the mountain-
ranges of the land. To judge correctly of the seeming irregularities,
it is necessary to consider that in chains like the Rocky Mountains,
or Andes, or Appalachians, the ridges vary their course many de¬
grees as they continue on, sometimes sweeping around into some
new direction, and then returning again more or less nearly to their
former course, and that the peaks of a ridge are very far from
being in an exact line even over a short course ; again, that several
approximately parallel courses make up a chain.
A. Northwesterly system of trends.—In the southwestern Pacific,
the New Hebrides (fig. 23) show well this linear arrangement; and
even each island is elongated in the same direction with the group.
This direction is nearly northwest (N. 40° W.), and the length of the
chain is 500 miles. New Caledonia, more to the southwest, has
approximately the same course,—about northwest. Between New
Hebrides and New Caledonia lies another parallel line, the Loyalty
Group. The Salomon Islands, farther northwestward, are also a
linear group. The chain is mostly a double one, consisting of two
parallel ranges, and each island is linear, like the group, and with
the same trend. The course is northwest-by-west, the length
600 miles.
GENERAL FEATURES OF THE EARTH.
31
In the North Pacific, the Hawaian range has a west-northwest
course. The Sandwich or Hawaian Islands (fig. 24), from Hawaii
Fig. 23.
15° S
170°
[\/l
E
°\
\ 4, \
... »
X
'o
< ^
•
//tiT
/J-ip :
///
"8 <?*
0
O
to Kauai, make up the southeasterly part of the range, about 400
miles in length. Beyond this the line extends to 175° E., making
Fig. 24.
155
,qk
f /NO
h4\A db
X
's> 3 rv.
20° N V*
3W
' y
>
II, Hawaii; M, Maui; 3, Kalioolawe; 4, Lauai;
C, Molokai; 0, Oaliu; K, Kauai.
a total length of nearly 2000 miles,—a distance as great as from
Boston to the Great Salt Lake in the Rocky Mountains, or from
London to Alexandria. Moreover, in this chain there are on
32 PHYSIOGRAPHIC GEOLOGY.
Hawaii two summits nearly 14,000 feet in altitude ; and if the
ocean around is 15,000 feet deep, the whole height of these peaks
is just that of Mount Everest in the Himalayas.
Between these groups lie the islands of the ocean, all nearly
parallel in their courses. Figs. 25, 20 are examples.
Fig. 25. Fig. 20.
0 0
*1
\
io°S
a o
Z t>
* *
140
\ 0
'w %
The following table gives the courses of the principal chains of the ocean :—
Course.
Ilawaian range X. 04° AY.
Alaripiesas Islands X. 0(1° AY.
Paumotu Archipelago X. 0(1° AY.
Ta'nitian or Society X. (12° AY.
Ilervoy Islands X. <>5° AY.
Samoan or Xavigator Islands X. GS° AY.
Tarawan or Kingsmill Islands X. 24° AY.
Raliek group X. :'>7° AY.
Itadack group.... X. 20° AY.
Xew Hebrides X. 40° AY.
Xew Caledonia X. 44° AY.
Xorth extremity of Xew Zealand X. 50° AY.
Salomon Islands X. 57° AY.
Louisiade group X. 7>(*>° AY.
Xew Ireland X. G5° AY.
B. Northeasterly system of trexds.—The body of New Zealand
has a northeast-by-north course. The line is continued to the south,
through the Auckland and Macquarie Islands, to 58° 8. To the
north, in the same line, near .40° 8., lie the Kermadec Islands, and
farther north, near 20° 8., the Tonga or Friendly Islands.
The Ladrones, north of the equator, follow the same general
course. It also occurs in many groups of the northwesterly system
characterizing subordinate parts of those groups. Thus, the west¬
ernmost of the Ilawaian Islands, Niliau, lies in a north-northeast
line, and the two lofty peaks of Hawaii have almost the same
bearing.
GENERAL FEATURES OF THE EARTH.
33
35. Pacific island-chains.—The groups of Pacific islands, with a
few exceptions, are not independent lines, but subordinate parts of
island-chains. There are three great island-chains in the ocean
which belong to the northwesterly system,—the Hawaian, the Poly¬
nesian, and the Australasian,—and, excluding the Ladrones, which
belong to the western Pacific, one belonging to the northeasterly
system, viz.: the Tongan or New Zealand chain.
(1.) Hawaian chain.—This chain has already been described.
(2.) Polynesian chain.—This chain sweeps through the centre of
the ocean, and has a length of 5500 miles, or nearly one-fourth the
circumference of the globe. The Paumotu Archipelago and the
Tahitian and Hervey Islands are parallel lines in the chain, forming
its eastern extremity; westward there are the Samoan and Tara-
wan groups and others intermediate; still northwestward there
are the Radack and Ralick groups, and in 20° N., on the same line,
Wakes Island.
Fig. 27.
1 to 10, the Polynesian chain: 1, Paumotu group; 2, Tahitian; 3, Rurutu group; 4, Hervey
group; 5, Samoan or Navigators'; 6, Vakaafo group; 7, Vaitupu group; 8, Kingsmill group;
9, Ralick; 10, Radack; 11, Carolines; 12, Marquesas; 13, Fanning group; 14, Hawaian.
a to h, part of the Australasian chain: a, New Caledonia; b, Loyalty group; c, New Hebri¬
des; d, Santa Cruz group; e, Salomon Islands; /, Louisiade group; g, New Ireland; h, Ad¬
miralty group.
In fig. 27 the positions and trends of the various groups in this
Polynesian chain are indicated by lines numbered from 1 to 10.
4
34
PHYSIOGRAPHIC GEOLOGY.
(a.) The chain, as is seen, consists of a series of parallel ranges
succeeding and overlapping along the general course, in the manner
illustrated on page 19, when speaking of mountains. (6.) It varies
its course gradually from west-northwest at the eastern extremity to
north-northwest at the western, (c.) Its mean trend is northwest-
by-west (N. 56° W.), the mean trend of all the groups of the north¬
westerly system in the ocean, (d.) The chain is a curving chain,
convex to the southward, and marks the position of a great central
elliptical basin of the Pacific having the same northwesterly trend.
The Hawaian is on the opposite side of it, slightly convex to the north.
The Marquesan range lies in the same line with the Fanning group to the
northwest, just north of the equator; and, if a connection exists, another great
chain is indicated,—a Marquesan chain.
(3.) Australasian chain.—New Hebrides and New Caledonia belong
to the Australasian island-chain. The line of New Hebrides is
continued northwestward in the Salomon group and New Ireland,
though bending a little more to the westward, and terminates in
Admiralty Land, near 145° E., where it becomes very nearly east-
and-west: the length of the range is about 2000 miles. Taking another
range in the chain, New Caledonia, the course is continued in the
Louisiade group; then the north side of New Guinea, which con¬
tinues bending gradually till it becomes east-and-west, near 135° E.:
and in the southeast, belonging to the same general line, there is the
foot of the New Zealand boot. The coral islands between New
Caledonia and Australia appear also to be other lines in the chain.
From New Guinea the east-and-west course is taken up by Ceram,
and again, more to the south, in the Java line of islands ; and from
Java the chain again begins to rise northward, becoming northwest
finally in Sumatra and Malacca.
The several ranges make up one grand island-chain, with a
double curvature, the whole nearly 6000 miles long. The relation
of the parts in the system is shown in figure 28, in which a line
stands for each group and indicates its course.
The composite nature of the chain is here apparent; as also the
curving course, in connection with a prevailing conformity to a
northwesterly trend.
(4.) Blending of the Australasian and Polynesian island-chains.—The
two chains blend with one another in the region of the Carolines.
This large archipelago properly includes the Ralick and Radack
groups. At the Tarawan group, just south, the Polynesian chain
divides into two parts,—the Ralick and Radack ranges. But the
main body of the archipelago (see fig. 27 and the chart) trends off to
GENERAL FEATURES OF THE EARTH.
35
the westward, and is a third branch, conforming in direction to
the Australasian system.
Fig. 28.
A, B, C, Sumatra and Java line of islands; D, Ceram; E, north coast
of New Guinea; F, South New Guinea; G, Admiralty Islands; H,
Louisiade group; I, Salomon; J, Santa Cruz group; K, New He¬
brides; L, Loyalty group; M, New Caledonia; N, high lands of
northeast Australia; 0, New Zealand; aft, northwest shore of Bor¬
neo; cd, east Borneo; ef, west coast of Celebes; g h, west coast of
Gilolo.
The Caroline Archipelago forks at its southeastern extremity,—
one portion, the Tarawan, Radack, and Ralick Islands, conforming
to the Polynesian system (8, 9, 10 in fig. 27), while the great body
of the Caroline Islands trend off more to the westward (No. 11),
parallel with New Zealand and the Admiralty group (g, h of the
same cut) and others of the Australasian system.
(5.) New Zealand chain.—The ranges in this chain are mentioned
in | 34. The whole length, from Macquarie Island, on the south,
to Vavau, a volcanic island terminating the Tonga range, on the
north, is 2500 miles. To the east of New Zealand lie Chatham Island,
Beverly, Campbell, and Emerald, which correspond to another range
in the chain.
This transverse chain is at right angles with the Polynesian system
at the point where the two meet. Moreover, it is nearly central
to the ocean; and in its course farther north lie the Samoan
and Hawaian Islands, two of the largest groups in the Polynesian
system.
The central position, great length, and rectangularity to the
northwest ranges give great significance to this New Zealand or
northeasterly system of the ocean.
36
PHYSIOGRAPHIC GEOLOGY.
The large Feejee group lies near the intersection of the three Pacific chains;
and hence its numerous islands do not conform to either one, though the larger
islands approximate most nearly to the last in direction.
36. (2.) Pacific and Atlantic Oceans.—The trend of the Pacific
Ocean as a whole corresponds with that of its central chain of
islands, and very nearly with the mean trend of the whole. It is a
vast channel, elongated to the northwest. The range of heights along
northeastern Australia runs from the eastern coast northwesterly,
by the head of the great gulf (Carpentaria) on the north ; and the
opposite side of the ocean along North America, or its bordering
mountain-chain, has a similar mean trend. A straight line drawn
from northern Japan through the eastern Paumotus to a point a
little south of Cape Horn may be called the axis of the ocean.
This axial line is nearly half the circumference of the sphere, and
the transverse diameter of the ocean full one-fourth the circum-
*
ference: so that the facts relating to the Pacific chains must have
a universal importance.
The North Atlantic Ocean trends to the northeast,—or at right angles,
nearly, to the Pacific: this is the course of the coasts, and therefore
of the channel. Taking the trend of the southeast coast of South
America as the criterion, the South Atlantic conforms in direction to
the North Atlantic.
The Asiatic coast of the Pacific has the direction of the north¬
easterly system. The course is not a nearly straight line, like the
corresponding eastern coast of North America, but consists of a
series of curves, which series is repeated in the outline of the Asiatig
coast and in the mountains of the country back. Moreover, the
curves meet one another at right angles.
The last one, which is 1800 miles long, commences in Formosa, and
extends along by Luzon, Palawan, and western Borneo, to Sumatra,
and terminates at right angles with Sumatra; and another furcation
of it passes by eastern Borneo or Celebes, and terminates at right
angles with Java and the islands just east (fig. 28). The rectangu-
larity of the intersections is thus preserved ; and the curve of the
Australasian chain has in this way determined the triangular form
of Borneo.
The Aleutian Islands (range No. 1) make a curve across from America to
Kamichatka, in length 1000 miles. The Kamtchatka range (No. 2) commences
at right angles with the termination of the Aleutian, and bends around till it
strikes Japan at a right angle. The Japan range (No. 3) commences north in
Saghalien, and curves around to Corea. The Loochoo range (No. 4) leaves Japan
at a right angle, and curves around to Formosa. The Formosa range (No. 5) is
explained above. There is apparently a repetition of the Formosa system in
the Ladrones near longitude 145° E.
GENERAL FEATURES OF THE EARTH.
87
37. (3.) East and West Indies.—The general courses m the
East Indies have been mentioned in $ 35. In the West Indies and
Central America there is a repetition of the curves in the East
Indies. The course of the range along Central America corresponds
to Sumatra and Java; the line of Florida and the islands to the
southeast makes another range in the same system.
The East and West Indies are very similar in their relations to
the continents and oceans. About the East Indies Asia lies to the
northwest and Australia to the southeast, just like North and
South America about the West Indies; and the North Pacific and
Indian Ocean have the same bearing about the former as the North
Atlantic and South Pacific about the latter. The parallelism in the
bends of the great chains is, hence, only a part in a wide system of
geographical parallelisms.
38. (4.) The American continents.—In North America the north¬
west system is seen in the general course of the Rocky Mountains,
the Cascade Range and Sierra Nevada; in Florida; in the line of
lakes, from Lake Superior to the mouth of the Mackenzie; in the
southwest coast of Hudson's Bay ; in the shores of Davis'Straits and
Baffin's Bay; and with no greater divergences from a common course
than occur in the Pacific. The northeast system is exemplified
in the Atlantic coast from Newfoundland to Florida, and, still
farther to the northeast, along the coast of Greenland; and to the
southwest along Yucatan, in Central America. The Appalachian
Mountains, the river St. Lawrence to Lake Erie, and the north¬
west shore of Lake Superior, repeat this trend.
There are curves in the mountain-ranges of eastern North Ame¬
rica like those of eastern Asia. The Green Mountains run nearly
north-and-south, but the continuation of this line of heights across
New Jersey into Pennsylvania curves around gradually to the
westward. The Alleghanies, in their course from Pennsylvania to
Alabama and Tennessee, have the same curve. There appears also
to be an outer curving range, bordering the ocean, extending from
Newfoundland along Nova Scotia, then becoming submerged, though
indicated in the sea-bottom, and continued by southeastern New-
England and Long Island.
Betwreen this range and that of the Green Mountains lies one of
the great basins of ancient geological time, while to the westward
of the Green Mountains and Alleghanies was the grand interior basin
of the continent. The two were to a great extent distinct in their
geological history, being apparently independent in their coal-
deposits and in some other formations.
In South America the north coast has the same course as the
38
PHYSIOGRAPHIC GEOLOGY.
Hawaian chain, or pertains to the northwest system; and the coast
south of the east cape belongs to the northeast system. Hence the
outline of the continent makes a right angle at the cape. The
northwest system is repeated in the west coast by southern Peru
and Bolivia, and the northeast in the coast of northern Peru to
Darien: so that this northern part of South America, if the Bolivian
line were continued across, would have nearly the form of a paral¬
lelogram. South of Bolivia the Andes correspond to the northeast
system, although more nearly north-and-soutli than usual.
39. (5.) Islands of the Atlantic.—The Azores have a west-north¬
west trend, like the Hawaian chain, and are partly in three lines,
Fig. 29.
"a>x
'-"Ok
"Y
p-
Azores, or Western Islands.
with evidences also of the transverse system. The Canaries, as Yon
Buch has shown, present two courses at right angles with one an¬
other,—a northwest and a northeast.
Again, the line of the southeast coast of South America extends
across the ocean, passes along the coast of Europe and the Baltic,
and the mountains of Norway and the feature-lines of Great Britain
are parallel to it.
f». Asia and Europe.—In Asia the Sumatra line, taken up by
Malacca, turns northward, until it joins the knot of mountains
formed by the meeting of the range facing the Pacific and that
facing the Tndian Ocean. At this point, and partly in continuation
of a Chinese range, commence the majestic Himalayas,—at first
east-and-west, at right angles with the termination of the Malacca
GENERAL FEATURES OF THE EARTH.
39
line, then gradually rising to west-northwest. The course is con¬
tinued northwestward in the Hindoo Cush, extending towards the
Caspian,—in the Caucasus, beyond the Caspian, and the* Carpa¬
thians, beyond the Black Sea. The northwest course appears also
in the Persian Gulf, and the plateaus adjoining, in the Red Sea, the
Adriatic and Apennines.
40. Recapitulation.—From this survey of the continents and
oceans it follows:—
That while there are many variations in the courses of the earth's
feature-lines, there are two directions of prevalent trends,—the north¬
westerly and the northeasterly ; that the Pacific and Atlantic have
thereby their positions and forms, the islands of the oceans their
systematic groupings, the continents their triangular and rectan¬
gular outlines, and the very physiognomy of the globe an accord¬
ance with some comprehensive law. The ocean's islands are no
labyrinths, the surface of the sphere no hap-hazard scattering of
valleys and plains; but even the continents have a common type
of structure, and every point and lineament on their surface and
over the waters is an ordered part in the grand structure.
It has been pointed out, first by Professor R. Owen, of Tennessee,® that the
outlines of the continents lie in the direction of great circles of the sphere,
which great circles are in general tangential to the arctic or antarctic circles.
By placing the north pole of a globe at the elevation 23° 28' (equal to the dis¬
tance of the arctic circle from the pole or the tropical from the equator), then,
on revolving the globe eastward or westward, part of these continental outlines,
on coming down to the horizon of the globe, will be found to coincide with it;
and on elevating the south pole in the same manner, there will be other coinci¬
dences. Other great lines, as part of those of the Pacific, are tangents to the
tropical circles instead of the arctic. But there are other equally important
lines which accord with neither of these two systems, and a diversity of excep¬
tions when we compare the lines over the surfaces of the continents and oceans.
Still, the coincidences as regards the continental outlines are so striking that
they must be received as a fact, whether we are able or not to find an explana¬
tion, or bring them into harmony with other great lines.
4. SYSTEM IN THE OCEANIC MOVEMENTS AND TEMPERATURE.
41. (1.) System of oceanic movements.—The general courses
of the ocean's currents are much modified by the forms and posi¬
tions of the oceans; but the plan or system for each ocean, north
* Key to the Geology of the Globe, 8vo, New York, 1857, and Am. Jour. Sci.
[2], xxv. 130.
40
PHYSIOGRAPHIC GEOLOGY.
or south of the equator, is the same. This system is illustrated
in the annexed figure (fig. 30), in which all minor movements
are avoided in order to present only the
predominant courses. W E is the equator
in either ocean; 30°, 60°, the parallels so
named; N, S, the opposite polar regions:
the arrow-heads show the direction of the
movement.
The main facts are as follow : —
(1.) A flow in either tropic (see figure)from
the east, and in the higher temperate latitudes
from the west, the one flow turning into the
other, making an elliptical movement. The
tropical waters may pass into the extratro-
pical regions in all longitudes, but the move¬
ment is appreciable only towards the sides of
the oceans.
(2.) A flow of a part of the easterly-flowing extratropical waters
(see fig. 30) outward towards the polar region, to return thence
with the polar waters mainly along the western side of the ocean
(though partly by the eastern).
(3.) A flow of the colder current under the warmer when the
two meet, since cold water, is heavier than warm.
(4.) A lifting of the deep-seated cold currents to the surface
along the sides of a continent, or island, or over a submerged bank,
as on the west coast of South America.
(5.) A movement of the circuit, as a whole, some degrees to the
north or south with the change of the seasons, or as the sun passes
to the north or south of the equator.
(G.) On the west side of an ocean (see fig. 30) the cold northerly
current is mainly from the polar latitudes ; on the east side it is
mainly from the high temperate latitudes, being the cooled extra-
tropical flow on its return.
(7.) The tropical current has great depth, being a profound
movement of the ocean, and it is bent northward in its onward
course by the deep, submerged sides of the continents. The Gulf
Stream has consequently its main limit 80 to 100 miles from the
American coast, where the ocean commences its abrupt depths
(g 17). Hence, a submergence of a portion of a continent suffi¬
cient to give the body of the current a free discharge over it
would have to be of great depth,—probably two thousand feet at
least.
42. The usual explanation of the courses is as follows:—As the
Fin-. 30.
13
.£■-
,A i 60°
IV E
Jl 30°
-A. ^fiQ°
% S-.
s
GENERAL FEATURES OF THE EARTH.
41
earth rotates to the eastward, the westward tropical flow is due
simply to a slight lagging of the waters in those latitudes. But
transfer these waters towards the pole, where the earth's surface
moves less rapidly (the rate of motion varies as the cosine of lati¬
tude), and then they may move faster than the earth's surface and
so have a movement to eastward. The earth's rotation is not sup¬
posed to be a cause of motion in the waters ; but, there being a move¬
ment, for other reasons (which it is not necessar}^ here to consider),
from the equator towards the poles, and from the higher latitudes
towards the equator, it gives easting to the flow in the former direc¬
tion, and westing to the flow in the latter.
On the same principle, any waters flowing from the polar regions
(where the earth's motion at surface is slow) towards the equator
would be thrown mainly against the west side of the oceans (as the
Labrador current in the North Atlantic), for they have no power to
keep up with the earth's motion. But the waters flowing towards
the pole, that have not lost much of their previous eastward-
m oving force, may descend to lower latitudes along the east side of
the ocean.
43. Put the above figure in either the Atlantic or Pacific, and
the system for the ocean will be apparent at a glance.
In the North Atlantic the deep tropical current from the east is
turned to the northward along the West India islands, and it there
becomes the Gulf Stream ; it flows by Florida to the northeast, fol¬
lowing nearly the outline of the oceanic basin ($ 17) ; it passes the
Newfoundland bank, and stretches over towards Europe; thenea
part bends southeastward to join the tropical current and complete
the ellipse; the centre of this ellipse is the Sargasso Sea, abounding
in seaweeds and calms. Another large portion continues on north¬
eastward over the region between Britain and Iceland to the poles.
From the polar region it returns along by Eastern Greenland, Davis'
Straits, and other passages, pressing against the North American
coast, throwing cold water into the Gulf of St. Lawrence, bringing
icebergs to the Newfoundland banks, and continuing on southward
to the West India islands and South American coast, where it pro¬
duces slight effects in the temperature of the coast-waters. Cape
Cod stands out so far that the influence of the cold current is less
strongly felt on the shores south than north ; and Cape Ilatteras
cuts off still another portion.
In the South Atlantic there is the tropical flow from the east:
the bending south towards Rio Janeiro; the turn across towards
Cape of Good Hope ; and the bending again northward of the
waters now cold. But, owing to the manner in which the channels
42
PHYSIOGRAPHIC GEOLOGY.
of tlie South Atlantic and North Atlantic are united, a large part
of the tropical current of the former goes to swell the tropical cur¬
rent and Gulf Stream of the latter.
In the North Pacific there is the same system, modified mainly
by this, that the connection with the polar regions is only through
the narrow and shallow Behring Straits. There is a current an¬
swering to the "Gulf Stream" off Japan, and another corresponding
to the "Labrador current" along the whole length of the Asiatic
coast, perceptible by the temperature if not by the movement.
In the South Pacific there are traces of a " Gulf Stream"—that is,
of an outward-bound tropical current—off Australia, noticed by
Captain Wilkes. The inward extratropical current, chilled by its
southern course, is a very important one to western South Ame¬
rica, as it carries cool waters quite to the equator.
In the Indian Ocean the system exists, but with a modification
depending on the fact that the ocean has no extended northern
area. The outward tropical current is perceived off southeast¬
ern Africa.
The surface-currents of the ocean are more or less modified by
changes in the winds. On this and on other related topics barely
glanced at in this brief review the reader may refer to treatises on
Meteorology or Physical Geography.
44. (2.) Oceanic temperature.—The movement of the oceanic
currents tends to distribute tropical heat towards the poles, and
polar cold, in a less degree, towards the tropics; and hence the
courses of the currents modify widely the distribution of oceanic
heat. The chart at the close of this volume contains a series of
oceanic isothermal lines drawn through places of equal cold for
the coldest month of the year. The line of 68° F., for example,
passes through points in which the mean temperature of the water
in the coldest month of the year is 08° F. ; so with the line of 62°,
56°, &c.* All of the chart between the lines of 68°, north and south
of the equator, is called the Torrid Zone of the ocean's waters ; the
region between 68° and 35°, the Temperate Zone, and that beyond 35°,
the Frigid Zone. The line of 68° is that limiting the coral-reef seas
of the globe, so that the coral-reef seas and Torrid Zone thus have
the same limits.
The regions between the successive lines, as 80° and 80°, 80° and 74°, 74° and
68°, 68° and 62°, 62° and 56°, 56° and 50°, and so on, have special names on
the chart. They are as follow :—
* As the lines are lines of equal extreme cold, instead of heat, such a chart
is named an isoerymal chart (from io-oj, equal, and extreme cold).
GENERAL FEATURES OF THE EARTH.
43
1. Torrid Zone.—Super-torrid, torrid, and sub-torrid regions.
2. Temperate Zone.—Warm-temperate, temperate, sub-temperate, cold-tem¬
perate, and sub-frigid regions.
3. Frigid Zone.
They are convenient with reference to the geographical distribution of oceanic
animals.
Since the tropical (the westward) currents are warm, and the
extratropical (the eastward) necessarily cold, the elliptical inter¬
play explained must carry the warm waters away from the equator
on the west side of the oceans, and the cold waters towards the
equator on the east side. The distribution of temperature thus
indicates the currents. In each elliptical circuit, therefore, the
line of 68° F. should be an oblique diagonal line to the ellipse;
and thus it is in the North Atlantic, the South Atlantic, the
North Pacific, the South Pacific (though less distinctly here, as the
ocean is so broad), and the Indian Ocean. The torrid-temperature
zones are very narrow to the eastward and broad to the westward.
The temperate zones press towards the equator against western
Africa and Europe, and western America. On the South American
coast this is so marked that a tropical temperature does not
touch the whole coast, except near the equator, and does not even
reach the Galapagos under the equator off the coast, as shown by
the course of the isothermal line of 68°. So in the South Atlantic
the colder waters extend north to within six degrees of the equator,
where the line of 68° leaves the African coast. The continuation
of the Gulf Stream up between Norway and Iceland is shown by
the great loops in the lines of 44° and 35°. The effect of the
Labrador or polar current in cooling the waters on the coast of
America is also well exhibited in the bending southward near the
coast of all the lines from 68° to 35°. The polar current is even more
strongly marked in the same way
on the Asiatic coast. The lines
from 74° to 35° have long flexures
southward adjoining the coast, and
the line of 68° comes down to within
15 degrees of the equator. These
waters pass southward mostly as a
submarine current, and are felt in
the East Indies, making a south¬
ward bend in the heat-equator.
In figure 31 the elliptical line (A'B' A B) represents the course of the current
in an ocean south of the equator (E Q). If now the movement in the circuit
were equable, an isothermal line, as that of 68°, would extend obliquely across,
Fig. 31.
44
PHYSIOGRAPHIC GEOLOGY.
as n n: it would be thrown south on the west side of the ocean by the warmth
of the torrid zone, and north on the east side by the cooling influence derived
from its flow in the cold-temperate zone. But if the current, instead of being
equable throughout the area, were mainly apparent near the continents (as is
actually the fact), then the isothermal line should take a long bend near the
coasts, as in the line A' >■' r r >■ r A, or a shorter bend A's according to the
nature of the current. This form of the isothermal line of 68° on the chart,
hence, indicates the existence of the circuit movement in the ocean, and also
some of its characteristics.*
45. The following are some of the uses of this subject to the
geologist:—
1. A wide difference is noted between the water-temperatures of
the opposite sides of an ocean. The regions named temperate and
sub-temperate occupy the most of the Mediterranean Sea, and the
Spanish and part of the African coast, on the European side, and
yet have no existence on the American, owing to the meeting at
Cape Hatteras of the cold northern waters with the warm southern.
Compare also other oceans and coasts on the map.
2. Consequently, the marine productions of coasts or seas in the
same latitudes differ widely. Corals grow at the Bermudas in 34°
N., where the warmth of the Gulf Stream reaches, and, at the same
time, are excluded from the Galapagos under the equator. Other
examples of the same principle are obvious on the chart.
3. The ivcst side of an ocean (as in the northern hemisphere)
feels most the cold northerly currents when the continent extends
into the polar latitudes ; but the east side (as in the southern hemi¬
sphere), if the continent stops short of those latitudes. There is
hence in the present age a striking difference between the northern
and southern hemispheres.
4. Changes of level in the lands of the globe have caused changes
of climates in the ancient world.
5. Knowing the temperature limiting the coral-reefs of the pre¬
sent era, or any species of plants or animals, the geologist has a
gauge for comparing the present distribution of temperature and
life with the past.
5. ATMOSPHERIC CURRENTS AND TEMPERATURE.
40. General System.—The system of atmospheric movement has
a general parallelism with that of the ocean. In the tropics the
flow is from the east, constituting what are called the trades; in high-
temperate latitudes it is from the west: and the two pass into one
* See paper by the author, in Amer. Jour. Sci. [2] xxvi. 231.
CLIMATE.
45
another in mutual interplay. Between these is, in mid-ocean, a
region of calms. The extratropical winds also in part pass on to
the poles, to return, as northeast, north, and northwest winds,
towards the equator.
The cause of the motion is not now considered, as it is here in place only
to present in a comprehensive manner the earth's exterior features. The
causes varying the directions consist in—(1) the temperature of the land and
ocean; (2) the form of the land (mountains being barriers to a flow, retarding
by friction, etc.); (3) difference of density of cold and warm air; (4) changing
seasons, etc. But these sources of disturbance only modify without suspend¬
ing the system of movement.
47. Climate.—Climate, while dependent largely on the latitude,
is modified by the atmospheric and oceanic movements and the
distribution of land and water. A few general facts are here men¬
tioned, in order to complete this survey of the earth's physiography.
1. The land takes up heat rapidly in summer, and, in the north,
becomes frozen and snow-clad in winter. Land-winds may, conse¬
quently, be intensely hot or intensely cold ; and hence lands have
a tendency to produce extremes of climate.
A place on the continents having a mean January temperature of 50° (a very
warm temperature for that season) is to be found only in warm latitudes, and
one with a mean July temperature of 50° (a cold temperature for the season)
only in the colder zones of the globe. The mean January temperature of New
York is 311° F., while the mean July temperature is 73°. Now, in North Ame¬
rica the January isothermal line of 50° almost touches the Gulf of Mexico, and
the July line of 50° passes near the mouth of Mackenzie River, or the arctic
circle,—the extreme winters and intense summers causing this great change.
In Asia, again, the January line of 50° runs just north of Canton, near 26° N.,
and the July line of 50° touches the Arctic Ocean at the mouth of the Lena, in
72° N., making a difference of 46° of latitude, or nearly 3000 miles, as the effect
of the land on the climate.
2. The waters of the oceans remain unfrozen even far into the
Arctic, unless crowded with lands, their perpetual movements tend¬
ing to produce a uniformity of temperature over the globe; and
hence winds from the oceans or any large body of water are
moderating, and never very cold. They produce what is called an
insular climate.
Great Britain is tempered in its climate by its winds and the oceanic current
(the Gulf Stream). Fuegia, which is almost surrounded bv water, also has an
insular climate,—the winter's cold falling little below 32°, although below 56°
S. latitude.
3. Absence of land from high latitudes is equivalent to an
absence of the source of extreme cold; and from tropical lati-
46
PHYSIOGRAPHIC GEOLOGY.
tudes, that of extreme heat; and the sinking of all lands would
diminish greatly both extremes. But sinking high-latitude lands
also diminishes the extreme of heat, since the lands become very
much heated in summer, and this heat is diffused by the winds.
Fuegia, on this principle, has a subalpine climate with alpine vege¬
tation ; and Britain might approximate to the same condition if
the Gulf Stream could be diverted into another ocean.
The mean temperature of the Northern hemisphere is stated by
Dove at 00° F., and of the Southern at 56° F., while the extremes
for the globe, taking the annual means, are 80° F. and zero. If there
were no land, the mean temperature would probably be but little
above what it is now, or not far from 60° for the whole globe.
6. DISTRIBUTION OF FOREST-REGIONS, PRAIRIES, AND
DESERTS.
48. The laws of the winds are the basis of the distribution of
sterility and fertility.
1. The warm tropical winds, or trades, are moist winds; and,
blowing against cooler land, or meeting cooler currents of air, they
drop the moisture in rain or snow. Consequently, the side of the
continents or of an island struck by them—that is, the eastern—
is the moister side.
2. The cool extratropical winds from the westward and high
latitudes are only moderately moist (for the capacity for moisture
depends on the temperature); blowing against a coast, and bending
towards the equator, they become warmer, and continue to take up
more moisture as they heat up; and hence they are drying winds.
Consequently, the side of a continent struck by these westerly cur¬
rents—that is, the western—is the drier side.
There is, therefore, double reason for the difference in moisture
between the opposite sides of a continent.
Consequently, the annual amount of rain falling in tropical
South America is 116 inches, while on the opposite side of the
Atlantic it is 76 inches. In the temperate zone of the United
States east of the Mississippi, the average fall is about 44 inches ;
in Europe, only 32. America is hence, as styled by Professor
Guyot, the Forest Continent; and where the moisture is not quite
sufficient for forests, she has her great prairies or pampas.
The particular latitudes of western coasts most affected by the
drying westerly winds—those between 28° and 32°—are generally
excessively arid, and sometimes true deserts. (W. C. Redfield, in
Amer. Jour. Sci. xxv. 139, 1834, and xxxiii. 261, 1838.)
CLIMATE.
47
The desert of Atacama, between Chili and Peru, the semi-desert
of California, the desert of Sahara, and the arid plains of Australia
lie in these latitudes. The aridity on the North American coast is
felt even beyond Oregon through half the year. The snowy peak
of Mount St. Helen's, 16,000 feet high, in latitude 43°, stands for
weeks together without a cloud. The region of the Sacramento
has rain ordinarily only during three or four months of the year.
As the first high lands struck by moist winds usually take away the
moisture, these winds afterwards have little or none for the lands
beyond. Here is the second great source of desert-regions. For
this reason, the region of the eastern Rocky Mountain slope, and
the summits of these mountains, are dry and barren ; and, on the
same principle, an island like Hawaii has its wet side and its
excessively dry side.
Under the influence of the two causes, Sahara is continued in an
arid country across from Africa, over Arabia and Persia, to Mon¬
golia or the Desert of Gobi, in central Asia.
It is well for America that her great mountains stand in the far
west, instead of on her eastern borders to intercept the atmospheric
moisture and pour it immediately back into the ocean. The waters
of the great Gulf of Mexico (which has almost the area of the
United States east of the Mississippi), and those of the Mediterra¬
nean, are a provision against drought for the continents adjoining.
It is bad for Africa that her loftiest mountains are on her eastern
border.
It is thus seen that prairies, forest-regions, and deserts are
located by the winds and temperature in connection with the
general configuration of the land.
49. The movements of the atmosphere and ocean's waters, and
the surface-arrangements of heat and cold, drought and moisture,
sand-plains and verdure, have a comprehensive disposing cause in
the simple rotation of the earth. Besides giving an east and west to
the globe, and zones from the poles to the equator, this rotation
has made an east and west to the atmospheric and oceanic move¬
ments, and thence to the continents, causing the eastern borders of
the oceans and land to differ in various ways from the western,
and producing corresponding peculiarities over their broad surface.
The continents, though in nearly the same latitudes on the same
sphere, have thence derived many of those diversities of climate and
surface which, through all epochs to the present, have impressed
on each an individual character,—an individuality apparent even
in its plants and animals. The study of the existing Fauna and
Flora of the earth brings out this distinctive character of each
PHYSIOGRAPHIC GEOLOGY.
with great force; but the review of geological history makes it still
more evident, by exhibiting the truth in a continued succession of
faunas and floras, giving this individuality a history looking back
to " the beginning."
The great truth is taught by the air and waters, as well as by the
lands, that the diversity about us, which seems endless and without
order, is an exhibition of perfect system under law. If the earth
has its barren ice-fields about the poles, and its deserts, no less
barren, towards the equator, they are not accidents in the making,
but results involved in the scheme from its very foundation.
PART II.
LITHOLOGICAL GEOLOGY.
50. Lithological Geology treats of the materials in the earth's
structure : first, their constitution; secondly, their arrangement or condition.
The earth's interior is open to direct investigation to a depth of
only fifteen or sixteen miles; and hence the science is confined to
a thin crust of the sphere, sixteen miles being but one-five-hun¬
dredth of the earth's diameter.
I. CONSTITUTION OF ROCKS.
51. Rocks.—A rock is any bed, layer, or mass of the material of
the earth's crust. The term, in common language, is restricted to
the consolidated material. But in Geology it is often applied to all
kinds, whether solid or uncompacted earth, so as to include,
besides granite, limestone, conglomerates, sandstone, clay-slates,
and the like solid rocks, gravel-beds, clav-beds, alluvium, and any
loose deposits, whenever arranged in regular layers or strata as
a result of natural causes.
The constituents of rocks are minerals. But these mineral con¬
stituents may be either of mineral or organic origin.
(1.) The material of organic origin is that derived from the remains
of plants or animals. This is the fact with the mass of nearly all
the great limestone formations ; for the substance of the rock was
made from shells, corals, or crinoids, triturated into a calcareous
earth by the sea, and afterwards consolidated, just as corals are
now ground up and worked into great coral reef-rocks in the West
Indies and Pacific. In other cases only a small part of a rock is
organic, the rest being of mineral origin. Such rocks usually con¬
tain distinct remains of the shells or corals that have contributed
to their formation: these relics, whether of plants or animals, are
called fossils, and the rocks are said to be fossiliferous.
(2.) The material of mineral origin includes all that is not directly
5 49
50
LITHOLOGICAL GEOLOGY.
of organic origin,—all the sancl, clay, gravel, etc., derived from the
trituration or wear of other rocks, or the material from chemical
deposition, like some limestones, or from volcanic action, like lavas
and trap or basalt.
But, whether organic or mineral in origin, the material when in
the rock, though sometimes under the form of fossils, is almost
solely in the mineral condition. The topics for consideration in
connection with this subject are, then, as follow :—
1. The elements constituting rocks.
2. The mineral material constituting rocks.
3. The kinds of rocks.
1. ELEMENTS CONSTITUTING ROCKS.
52. General considerations.—In the foundation-structure of the
globe firmness and durability are necessarily prime qualities,
while in living structures instability and unceasing change are
as marked characteristics.
These diverse qualities of the organic and inorganic world proceed
partly from the intrinsic qualities of the elements concerned in each.
In the inorganic kingdom,—
(1.) The elements which combine with oxygen to become the
essential ingredients of rocks are mainly hard and refractory sub¬
stances : as, for example, silicon, the basis of quartz; aluminium, the
basis of clay ; magnesium, the basis of magnesia.
(2.) Or, if unstable or combustible elements, they are put into
stable conditions by combination with oxygen. Thus, carbon,
which we handle and burn in charcoal, becomes burnt carbon (that
is, carbon combined with oxygen, forming carbonic acid) before it
enters into the constitution of rocks. So all minerals are made of
burnt compounds,—called burnt because ordinary combustion consists
in union with oxygen and the production of stable oxyds. They
are therefore dead or inert in ordinary circumstances, and hence
fit for dead nature. The metals potassium and sodium burn if put in
contact with water, and become oxyds. They are made into these
stable oxyds, potash and soda, before entering as ingredients into
rocks. Calcium also becomes lime,—one of the most refractory of
substances; and magnesium magnesia,—even more refractory than
lime. Silicon unites with its full allowance of oxygen in order to
form quartz, the most abundant compound in the mineral kingdom
and the least liable to change. Aluminium combines with a satu¬
rating quantity of oxygen to form alumina, the constituent of sap¬
phire and emery, the characterizing ingredient of clay, and hardly
less universal than quartz.
CONSTITUENT ELEMENTS OF ROCKS.
51
In organic nature, on the contrary,—
(1.) The essential elements are combustible substances, and mostly
gases,—oxygen combined with carbon and hydrogen forming plants,
and oxygen with carbon, hydrogen, and nitrogen forming animal
substances.
(2.) The elements in living beings, moreover, are not saturated
with oxygen: they are therefore in an unstable and constrained
condition. Both from their nature and their peculiar condition,
they have a strong tendency to take oxygen from the atmosphere
wTith which they are bathed or penetrated, and combine with
it. This state of strong attraction for oxygen — for something
not in the structure itself—is the source of activity in the vital
functions, and involves unceasing change as the means of existence
and growth, and a final dissolution of the structure at the cessa¬
tion of life.
Hence strength and durability belong to the basement-material
of the globe, and instability to living structures.
But inorganic nature is still not without change. For there are
diversities of attraction among the elements and their compounds.
The changes are, however, slow, and not essential to the existence
of the compounds. The processes of solution, of oxydation and
deoxydation, and other chemical interactions, changes by heat,
and other molecular and mechanical influences, give a degree of
activity even to the world of rocks. But this topic belongs to the
dynamics and chemistry of geology.
53. Characteristic elements.—The elements most important in
rocks are the following:—
(1.) Oxygen.—Oxygen is a constituent of all rocks, and composes
about one-half by weight of the earth's crust.
Sand is, by weight, more than half oxygen; quartz, the principal material
of sand, is about 53 per cent, oxygen; common limestone, 48 per cent.;
alumina, nearly 47 per cent.; feldspar, 40 to 50 per cent.; common clay, 50
per cent.: and thus it is with the various ordinary rocks. Besides, the atmo¬
sphere contains 23 per cent, of oxygen, and water—the material of the oceans,
lakes, and rivers—89 per cent.
(2.) Silicon.—After oxygen, silicon is the element next in abun¬
dance, constituting at least a fourth of the earth's crust. It is
unknown in nature in the pure state; but combined with oxygen,
and thus forming silica or quartz, it is common everywhere. This
silica is an acid, although tasteless; and its combinations with alu¬
mina, magnesia, lime, and other bases (called silicates), along with
quartz, are the principal constituents of all rocks except the lime¬
stones. Silica constitutes about 60 per cent, of these ingredients;
52
LITHOLOGICAL GEOLOGY.
and, including the limestones, 50 per cent, of all rocks. Silicon has
therefore the same prominent place in the mineral kingdom as
carbon in the organic.
Granite and gneiss are nearly three-fourths silica,—half of it as pure quartz,
and the rest as silicates ; mica schist and roofing-slate are about two-thirds
silica; trap and lavas are one-half; porphyry, two-thirds; sandstones are
sometimes all silica, and usually at least four-fifths.
Silica is especially adapted for this eminent place among the
architectural materials of the globe by its great hardness, its inso¬
lubility and resistance to chemical and atmospheric agents, and
its infusibility. As it withstands better than other common mine¬
rals the wear of the waves or streams, besides being very abundant,
it is the prevailing constituent of sands, and of the movable mate¬
rial of the earth's surface, as well as of many stratified rocks ; for
the other ingredients are worn out by the quartz under the con¬
stant trituration. It is also fitted for its prominent place by its
readiness in forming siliceous compounds and the durability of
these silicates. Moreover, although infusible and insoluble, many
oxyds enable heat to melt it down and form glass; or, if but a trace
of alkali be contained in waters, those waters, if heated, have the
power of dissolving it; and, thus dissolved, it may be spread
widely, either to enter into new combinations, or to fill with quartz
fissures and cavities among the rocks, thereby making veins and
acting as a general cement and solidifier.
Its applications in world-making are, therefore, exceedingly
various. In all, its action is to make stable and solid.
(3.) Aluminium.—Aluminium is a white metal, between tin and
iron in many of its qualities, but as light as chalk. Combined with
oxygen it forms alumina (APO3), the basis of clay. This alumina
is the gem sapphire, which is next in hardness to the diamond,
and of extreme infusibility and insolubility. Alumina is the most
common base in the silicates, thereby contributing to a large part
of all siliceous minerals, and therefore of all rocks. With quartz
these compounds (aluminous silicates) make granite, gneiss, mica
schist, syenite, and some sandstones, and alone they form porphyry
and other igneous rocks. Nearly all the rocks, except limestones
and some sandstones, are literally ore-beds of the metal aluminium.
(4.) Magnesium.—This metal combined with oxygen forms mag¬
nesia (MgO), a very refractory and insoluble base, producing with
silica a series of durable silicates, very widely distributed: some are
quite hard, as hornblende and pyroxene; others are soft, and have
a greasy feel, like talc, soapstone, and serpentine.
CONSTITUENT ELEMENTS OF ROCKS.
58
Unlike alumina, magnesia unites with carbonic acid, forming car¬
bonate of magnesia (MgO,C02).
(o.) Calcium.—The oxyd of the metal calcium is common quick¬
lime. Like magnesia, it enters into various silicates; and it also
forms a carbonate, carbonate of lime (Ca0,C02), and this carbonate is
the material of limestones. Moreover, with sulphuric acid and water
it forms sulphate of lime, or gypsum.
The peculiar position of lime in the system of nature is that of
a medium between the organic and inorganic world. Carbonate of
lime is soluble in water which holds a little carbonic acid in solu¬
tion ; and both this and the sulphate are found in river, marine, and
well waters. It is made into shells, corals, and partly into bone
by animals, and then turned over to the inorganic world to make
rocks. Lime is, therefore, the medium by which organic beings aid
in the inorganic progress of the globe, as above stated: far the
greater part of limestones have been made through the agency
of life, either vegetable or animal.
Lime also unites with phosphoric acid, forming phosphate of lime,
the essential material of bone, and a constituent also of other
animal tissues. Like the carbonate, this phosphate is afterwards
contributed to the rock-material of the globe, and is one source
of mineral phosphates.
(G.) (7.) Potassium and sodium.—Potassium is the metallic base
of potash, and sodium of soda. The alkalies potash and soda,
besides some other oxyds, form glass or fusible compounds with
silica; and this fact indicates one of their special functions in the
earth's structure. Silica, alumina, and the pure silicates of alu¬
mina are quite infusible; but by the addition of the alkalies, or
the oxyds of iron or lime, fusible compounds are formed. And,
as the earth's early history was one of universal fusion, the alkalies
performed an important part in the process, as they have since in
all igneous operations. Feldspars, which are found in all igneous
rocks, are silicates of alumina with potash, soda, or lime. A heated
solution of potash or soda will also dissolve silica, and so aid in
distributing quartz or making silicates.
Sodium is likewise the basis of common salt in sea-water.
(8.) Iron.—Iron combines with oxygen and forms two com¬
pounds, a protoxyd FeO, and a sesquioxyd Fe203, and one or the
other occurs along with alumina, magnesia, or lime in many sili¬
cates, which are mostly fusible. Silica and magnesia or lime with
protoxyd of iron make part of the very abundant mineral horn¬
blende, found in syenite, hornblendic slate, etc.; and also the
54
LITHOLOCilCAL GEOLOGY.
equally common pyroxene, characteristic of the heavy, dark-colored
lavas.
(9.) Carbon.—Carbon is well known in three different states,—that
of the diamond, the hardest of known substances, that of graphite
or black lead, and that of charcoal. Combined with oxygen it
forms carbonic acid (CO2); and carbonic acid combined with lime
makes carbonate of lime, or common limestone ; with magnesia,
carbonate of magnesia, or magnesite; with protoxyd of iron, car¬
bonate of iron, or spathic iron ; etc.
Carbonic acid exists in the atmosphere, constituting ordinarily
about one part in twenty-five hundred by weight.
This acid is the only acid in the mineral kingdom, in addition to silica, which
enters very largely into the constitution of rocks; and, while silica has alumina
and other sesquioxyds wholly to itself, carbonic acid shares with it in the mag¬
nesia, lime, and alkalies, that is, in all the protoxyds. Carbon, we have said,
performs as fundamental a part in living nature as silicon in dead nature; and
it is mainly through living beings that it reaches the mineral kingdom and forms
limestones and coal-beds. The deposits of carbonate of lime that have been
produced by direct chemical deposition from the waters of the globe are small
compared with those made of organic remains of plants or animals.
The nine elements above mentioned, oxygen, silicon, aluminium, magnesium,
calcium, potassium, sodium, iron, and carbon, are the prominent constituents of
rocks, making up 977-1000ths of the whole.
(10.) Sulphur.—Sulphur exists native in volcanic and some other regions.
In combination with various minerals it forms ores called sidphurets, as sul-
phuret of iron, or pyrites, sulphuret of copper, sulphuret of silver. But these
sulphurets do not constitute properly beds of rock; although one of them,
pyrites, is very abundant. Sulphur forms with oxygen two acids, sulphurous
acid (SO2), and sulphuric acid (SO3). Sulphuric acid united with lime makes
sulphate of lime, or gypsum, which sometimes occurs in extensive beds. There
are also many other sulphates, but none as true rock-constituents.
(11.) Hydrogen with oxygen constitutes water; and water, besides being
abundant over the earth's surface, is a constituent of many minerals. Gypsum
contains 21 per cent., serpentine 13 per cent., tale 5 per cent.
(12.) Chlorine with sodium forms clilorid of sodium, or common salt, which is
found in large beds, as well as dissolved in sea-water and brine-springs.
(13.) Nitrogen is an ingredient of the atmosphere,—making 77 per cent, of it.
AVith oxygen it forms nitric acid (NO5); but no nitrates enter prominently into
the structure of rocks.
The thirteen elements mentioned are all that occur as important
rock-constituents. Others require attention in discussing topics
connected with chemical geology, in which department the pro-
foundest knowledge of chemistry and mineralogy is none too much.
But in a general review of rocks only these thirteen need be con¬
sidered.
CONSTITUENT MINERALS OP ROCKS.
55
2. MINERALS CONSTITUTING ROCKS.*
1. Quartz, and Silicates containing alumina, without water.
54. (1.) Quartz.—Quartz is the first in importance. It occurs in
crystals, like figs. 32 and 33 ; also massive, with a glassy lustre.
Hardness too great to be scratched with a knife; varies in color
from white or colorless to black, and in trans¬
parency from transparent quartz to opaque.
It has no cleavage,—that is, it breaks as easily
in one direction as another, like glass. Be¬
fore the blowpipe it is infusible, unless heated
with soda, when it fuses easily to a glass.
Clear kinds are called limpid quartz; violet
crystals are the amethyst; compact translucent,
with the colors in hands or clouds, agate; or without bands or clouds,
chalcedony; massive, of dark and dull color, with the edges trans¬
lucent, flint; the same with a splintery fracture, hornstone; the same
more opaque, lydianstone or basanite; the same of a dull red, yellow,
or brown color, and opaque, jasper; in aggregated grains, sandstone
or quartzite; in loose, incoherent grains, ordinary sand.
Silica also occurs in another state, constituting opal, a well-known
mineral. In this state it is easily dissolved in a heated solution of
potash, while quartz is not so dissolved. Opal usually contains some
water, and is a little softer than quartz.
55. (2.) Feldspar.—Feldspar is next in abundance to quartz.
Under this name several species are included, all of which contain
silica and alumina; but one has, in addition, potash, and is a potash-
feldspar; another, soda,—a soda-feldspar; another, lime,—a lime-feld¬
spar ; and others, both soda and potash, or soda and lime. They
are all similar in being nearly as hard as quartz ; in having a lustre
somewhat like quartz, though partly pearly on smooth faces; in
general, only light colors, white and flesh-red being most common ;
also a broad, even, lustrous cleavage-surface, with a second cleavage
nearly or quite at right angles with the other, and but little less
perfect. Specific gravity, between 2.4 and 2.8. Before the blowpipe,
* The ordinary characters by which minerals are distinguished are—relativ e
hardness, as ascertained by a file, a point of a knife, or by scratching one mine¬
ral with another; specific gravity, or relative weight; lustre and color ; crystal¬
line form; cleavage (cleavage being a facility of cleaving or breaking in some
one or more directions, and affording even, lustrous surfaces, as in mica, gypsum,
feldspar); fusibility; chemical composition.
56
LITHOLOGICAL GEOLOGY.
melts with difficulty. The lustrous cleavage-surface serves to
distinguish it from quartz when the two occur together, as in
granite.
In the feldspars the ratio of the alumina to the protoxyd bases (potash, soda,
or lime) is uniformly 1:1.
a. Orthoclase, or potash-feldspar, is the most common, and is often called
common feldspar. Crystals as in the annexed
figures (monoclinie). The two cleavage-
planes are at right angles with one another.
Colors, usually white or flesh-red. Composi¬
tion : Silica, 64.8, alumina, 18.4, potash, 16.8
= 100. Ratio of the potash, alumina, and
silica. 1:1:4.
b. Albite, or soda-feklspar, is also common.
Color, generally white, whence the name (from the Latin albus, white). Crystals,
triclinic: the two cleavage-planes incline to one another at the angle 93° 36'.
Plane 0 of crystals often striated in only one direction. Composition: Silica,
68.7, alumina, 19.5, soda, 11.8. Ratio of the soda, alumina, and silica, 1:1:4.
Some albites contain a little potash, and some orthoclases a little soda.
c. Oligoclase, a lime-and-soda feldspar. Resembles albite in crystallization
and appearance. Ratio of the protoxyds (lime and soda), alumina, and silica,
1:1:3. Andesine is another lime-and-soda feldspar. Ratio of the protoxyds,
alumina, and silica, 1:1:2$. They are distinguished from albite with difficulty
without chemical analysis.
d. Labradorite, or lime-feldspar. Colorless to grayish and smoky brown,
and usually with beautiful internal reflections. Crystallization nearly as in
albite. Composition : Silica, 53.1, alumina, 30.1, lime, 12.3, soda, 4.5. Ratio of
protoxyd bases, alumina, and silica, 1:1:2.
c. Anorthite is another lime-feldspar, but of less common occurrence, being
mostly confined to certain volcanic rocks. Composition: Silica, 43.2, alumina,
30.8, lime, 20.0. Ratio of lime, alumina, and silica, 1:1:1J.
Anorthite and labradorite differ from the other feldspars in containing pro¬
portionally less of silica and being decomposable easily by acids.
56. (3.) Mica.—Readily distinguished by its splitting easily into
very thin elastic leaves or scales,—even thinner than paper,—and its
brilliant lustre. It is colorless to brown, green, reddish, and black.
It may occur in small scales,—as common in granite as one of its
constituents.—or in plates a yard in diameter.
As with the feldspars, mica is a silicate of alumina and different bases with
usually some fluorine, and is of several kinds, which differ in composition and
optical characters more than in appearance. Some of the varieties resemble
talc and chlorite, from which they differ in being elastic (unless weathered).
a. Muscovite, or common mica, is a potash-mica. Its crystals, when distinct,
are oblique prisms, and by polarized light it affords two sets of rings, with the
angle between the two axes 60° to 75°. Composition: Silica, 48, alumina,
CONSTITUENT MINERALS OF ROCKS.
57
36, sesquioxyd of iron and manganese, 5.0, potash, 10, fluorine, 1.0. A variety
called lepidolite has often a violet color and contains lithia.
b. Phlogopite.—A magnesia-mica. Crystals right prisms, rhombic or hexa¬
gonal. Color, yellowish-brown to white, often a little like copper in its reflections.
By polarized light, biaxial, with the angle between the axes 5° to 20°. Contains,
besides silica, alumina, and magnesia, some potash and oxyd of iron. Found
mostly in crystalline limestones.
c. Biotite.—A magnesia-mica, usually containing much oxyd of iron. Crys¬
tals right or oblique prisms. Color, often black, and greenish black; rarely
white. By polarized light, nearly or quite uniaxial, the angle between the axes,
when distinctly biaxial, but 1° or 2°. Contains, besides silica, alumina, and mag¬
nesia, much oxyd of iron and some potash.
Fig. 36. Fig. 37.
22 \ \
aj 1
57. (4.) Garnet.—Crystals usually dodecahedrons (fig. 36, imbedded in the
rock), trapezohedrons (fig. 37), and combinations of these forms, and commonly
imbedded in gneiss, mica slate, and other crystalline rocks. Color, clear wine and
cinnamon red to reddish-brown and black; rarely green. Hardness equal
to that of quartz, and therefore not scratched by a knife. G. = 3.1-4.3, the
heavier kinds containing much iron. Before the blowpipe, fuses rather easily.
Composition: Silica and alumina, with either lime, magnesia, or oxvds of iron,
and sometimes protoxyd of manganese or chromic oxyd. The lime variety
(cinnamon-stone) contains silica, 40.1, alumina, 22.7, lime, 37.2. But some oxyd
of iron is generally present; and common garnet contains silica, 36.3, alumina,
20.5, protoxyd of iron, 43.2. The ratio of protoxyds, peroxyds, and silica is
1:1:2.
Idocrase resembles garnet closely in color, composition, and fusibility, but
is square-prismatic in its crystals, and brownish in color like some brown
garnet and tourmaline.
(5.) Leucite.—In trapezohedral crystals like garnet, but white or gray and
without cleavage. Hardness nearly that of feldspar. G. = 2.45-2.5. Occurs
in Vesuvian lavas in crystals and grains. Composition: Silica, 55.1, alumina,
23.4, potash, 21.5.
58. (6.) Epidote. — Crystals oblique prisms (monoclinie). Also, occurring
massive, with a granular or columnar structure. Prevailing color, a peculiar
yellowish green, but varying to brown, ash-gray, and white. Hardness = 6-7, or
nearly that of quartz. G. — 3.2-3.5. Composition : Constituents, same essen¬
tially as in garnet, but ratio 3:2: 3. There is a lime variety, containing silica,
42.5, alumina, 31.5, lime. 26.0 : and a lime-and-iron variety, containing silica,
39.5, alumina, 19.5, pernxyd of iron, 17.0, lime, 24.0.
58
LITHOLOGICAL GEOLOGY.
59. (7.) Scapolite.—Crystals square and eight-sided prisms, and often large
and cleaving imperfectly parallel to the sides of the square prism. (See fig. 38.)
Color, white, gray, or greenish gray, and looking much like feldspar, though
Fig. 38.
I it I
distinct in crystallization and cleavage. Hardness but little below that of
feldspar. G. = 2.6-2.75. Composition: Silica, 49.3, alumina, 27.9, lime, 22.8,
but usually containing some soda.
60. (8.) Andalusite.—Occurs in whitish or grayish prismatic crystals,
nearly square (angle of 90° 44'), and often having the interior tessellated with
black (fig. 39), in which case it is usually called made, or chiastolite. Hard¬
ness, if pure, greater than that of quartz. G. = 3.1-3.2. Before the blowpipe,
infusible. Composition: Silica, 37.0, alumina, 63.0.
61. (9.) Staurotide.—In rhombic prisms of a large angle (129° 20'), often
having the acute edges removed so as to be six-sided. Often in crossed crystals
(fig. 40), whence the name, from the Greek
aravpos, a cross. Crystals usually thick
and coarse, sometimes fine lustrous. Color,
brown to black. A little harder than
quartz. G. = 3.5-3.75. Before the blow¬
pipe, infusible. Composition : Silica, 29.3,
alumina, 53.5, peroxyd of iron, 17.2.
62. (10.) Kyanite.—In flattened, blade¬
like, rarely thick prisms, blades often
aggregated into masses. Color, sky-blue
to white, usually deeper blue along the
middle. Hardness of the extremities of the prisms as great as that of quartz.
G. = 3.5-3.7. Before the blowpipe, infusible. Same composition as anda-
lusite. Sillimanite is similar in composition, but
has a brownish to grayish color, a brilliant cleavage
in one direction, and it often runs into fibrous forms.
G. = 3.2-3.3.
63. (11.) Tourmaline.—In three, six, nine, or
twelve-sided prisms (figs. 41, 42), without vertical
cleavage, and when black a little pitch-like in the
cross-fracture. Color, commonly black ; also brown ;
rarely green, and pink or carmine-red. As hard as
quartz. G. = 2.9-3.3. The crystals are thick or coarse, and often penetrate
quartz (fig. 43) in long black prisms as large as a goose-quill; also found in mica
Fig. 39.
Fig. 40.
CONSTITUENT MINERALS OF ROCKS.
59
schist in long or short prisms, frequently as large as the finger, or larger, and
in soapstone in black or brown crystals, long or short. Before the blowpipe
Fig. 43.
the common varieties fuse easily. Composition peculiar in the presence of
boracic acid; the other constituents, besides silica and alumina, are commonly
some magnesia, oxyd of iron, soda, and fluorine.
64. (12.) Topaz.—In rhombic prisms (figs. 44, 45) of 124° 19', having a bril¬
liant and easy cleavage parallel to the base. Sometimes columnar-massive.
Color, pale yellow, white, brown; often transparent. Harder than quartz.
G. = 3.4-3.7. Before the blowpipe, infusible. Composition peculiar in the large
amount of fluorine present; contains—Silica, 35.27, alumina, 54.92, fluorine, 17.14.
Beryl.—In regular six-sided prisms, without distinct cleavage. Color,
usually pale green; in the emerald—a variety of beryl—deep and clear green;
also yellowish, bluish, brownish, white. Hardness above that of quartz.
G. = 2.65-2.75. Infusible. Composition peculiar in containing glucina. Com¬
position: Silica, 66.9, alumina, 19.0, glucina, 14.1 — 100.
2. Protoxyd-Silicates, not containing water.
65. (13.) Hornblende (often called Amphibole).—In oblique prism¬
atic crystals (monoclinic) of 124° 3CK, with cleavage parallel to the
faces; often having the acute edges truncated so as to be six-sided
and approach a regular hexagonal prism. The crystals often long
and thin (fig. 48), or aggregated into masses, or penetrating the
rock (fig. 49); sometimes short and stout (figs. 46 and 47). Color,
Fig. 46. Fig. 47. Fig. 49.
black and greenish-black, common either in distinct, stout crystals,
or fibrous; also in short and stout green crystals; also in long
GO
LITHOLOGICAL GEOLOGY.
green prisms and fibrous masses, when it is called actinolite; or in
grayish and brownish-green fibrous or acicular forms, when it is
called anthophyllite; also in long white prisms and fibrous masses,
when it is called tremolite; also in short, thick, white prisms, called
■white hornblende; also in very delicately-fibrous masses, the fibres
flexible like flax, when it is called asbestus; also in rock-masses
made of coarse cleavable grains. Hardness nearly or quite that
of feldspar. Hornblende rocks, very tough. Before the blowpipe,
somewhat fusible. Composition: Silica, with magnesia, lime, prot-
oxyd of iron (and sometimes protoxyd of manganese), with occa¬
sionally a little alumina. A Ihne-enid-magnesia variety contains—
Silica, 60.7, lime, 12.5, magnesia, 26.8; an iron-and-magnesia variety—
Silica, 58.6, magnesia, 25.9, protoxyd of iron, 15.5.
(14.) Pyroxene (often called Augite).—In oblique prismatic crys¬
tals (monoclinic) of 87° 5/, and therefore nearly square, with cleav¬
age parallel to the faces, often having all four edges replaced so as
to make an eight-sided prism. In colors, hardness, specific gravity,
and composition, like hornblende. Cleavable, massive kinds of a
dingy grayish-green color are called sahlite. In
volcanic rocks the crystals are black, rather
small, and like figs. 50 and 51 in form; in meta-
morphic rocks they are usually grayish green,
and often large and coarse. In serpentine dial-
lage is common, and with labradorite hyper-
sthene frequently occurs. Before the blowpipe,
like hornblende: some foliated varieties infusible. Composition:
The pale-green varieties contain—Silica, 55.7, magnesia, 18.5, lime,
25.8. Others of dark-green and black colors, Silica, 53.7, magnesia,
13.4, lime, 24.9, protoxyd of iron, 8.0; or, Silica, 48.6, lime, 22.5,
protoxyd of iron, 28.9.
If </uw-foliated, the brittle folia often partly separable, called
hypersthenc when brownish green or bronze-like, and diallage when
grass-green.
(15.) Chrysolite.—In small grains disseminated through basaltic
rocks and many lavas, also in imbedded masses and rectangular
crystals. Appearance glassy, and often dark green like bottle-glass,
(a variety called olivine): also pale green. Hardness nearly that of
quartz. G. = 3.3-3.5. Infusible, excepting some kinds contain¬
ing much iron. Composition: essentially a silicate of magnesia, or
magnesia and iron: a common kind contains—Silica, 41, magnesia,
50, protoxyd of iron, 9.
(16.) Chondrodtte.—In large and small grains or masses imbedded usually
CONSTITUENT MINERALS OF ROCKS.
61
in granular limestone. Color, pale yellow and brownish yellow. Brittle, without
cleavage or much lustre. Hardness, as with chrysolite. G. = 3.1-3.24. Com¬
position: nearly like chrysolite, but containing fluorine : Silica, 33, magnesia, 50,
protoxyd of iron, 3, fluorine, 8.
3. Protoxyd-Silicates containing water.
66. (17.) Talc.—In foliated masses; folia flexible, but not elastic;
also compact-massive, very soft, and having a greasy feel, either
granular, or very compact without any appearance of grains, when
it is called soapstone or steatite. G. = 2.5-2.8. Before the blowpipe,
infusible. Composition: a silicate of magnesia; Silica, 62.12, mag¬
nesia, 32.94, water, 4.94.
(18.) Serpentine.—Usually massive, without cleavage or any gra¬
nular texture, and soft enough to be scratched easily by a knife.
Sometimes thin-foliated, with the folia brittle; also delicately fibrous,
and then often called amianthus and chrysotile. Sometimes in rectan¬
gular and rhombic prisms. Color, dark to light green. Before the
blowpipe, fuses with difficulty on thin edges. G. = 2.2-2.6. Com¬
position: Silica, 43.6, magnesia, 43.4, water, 13.0.
(19.) Chlorite.—Thin micaceous, like mica, but folia not elastic,
and color olive-green, rarely whitish. Commonly massive, with a
fine granular texture, and of massive varieties. Quite soft, so as to
be cut easily with a knife. G. = 2.7-3. Before the blowpipe,
more or less fusible. Composition: Silica, 27.2, alumina, 23.1,
magnesia, 13.5, protoxyd of iron, 24.2, water, 12.1. This mineral
contains alumina, like those of the following subdivision ; but its
magnesia gives it its character, and it is usually associated with
other magnesian rocks.
Clinochlore and ripidolite are names of other chlorites. (See author's Mine¬
ralogy.)
4. Alumina-Silicates containing water.
67. (20.) Agalmatolite.—A compact material, resembling steatite, without
any distinct grain, white or grayish in color, and easily cut with a knife. It is one
of the kinds of materials cut into images in China. Specific gravity, 2.7-2.9.
It is a silicate of alumina and potash, containing about 46 per cent, of silica, 32
of alumina, 8 of potash, and 7 per cent, of water, with traces of some other in¬
gredients. The Parophite of Hunt is a rock of similar composition, from Canada :
and the dysyntribite of Shepard is a related compound, from northern New
York, of grayish green, brownish, and other shades of color. In the vicinity
of the dysyntribite large hexagonal crystals have been found, resembling the
Gieseekite of Greenland, and showing that gieseckite also belongs here, as ascer¬
tained by G. J. Brush. These crystals, and also the gieseckite, are supposed
to be altered nepheline.
62
LITIIOLOGICAL GEOLOGY.
Pyrophvllite.—A mineral resembling talc in its appearance and soapy feci,
but consisting of silica, 66, alumina, 29, water, 5. There is a massive waxy
variety, which resembles the pagodite and some soapstone. The massive pyro-
phyllite dilfers from pagodite in containing no alkali and more silica. The
preceding hydrous silicates of alumina have the soapy feel of talc, a hydrous
silicate of magnesia, and by most persons would on first examination be pro¬
nounced magnesian. They are the basis of a slaty rock much like talcose elate,
but containing no magnesia,—a point of interest to the geological observer.
68. (21.) Zeolites and related minerals.—The zeolites are hydrous minerals,
consisting of silica and alumina, with lime or an alkali. They resemble the
feldspars closely in composition, but contain water, are less hard and more
fusible. They occur in cavities and veins in igneous rocks, or disseminated
through the mass of the rocks; also in cavities in granite and some other feld-
spathic rocks. The following are the more prominent:—
a. Analcime: occurs in trapezohedral crystals, glassy and clear, or white.
Hardness a little less than that of feldspar.
b. Chabazite: in rhombohedral crystals, nearly cubic, white and reddish.
c. Natrolite: in fibrous masses and acitfular crystals, usually white, without
a pearly cleavage. Scolecite closely resembles natrolite.
d. Stilbite: in flattened prisms with dihedral summits, and having a broad,
pearly cleavage-surface parallel to one face of the prism; prisms often grouped
into sheath-like forms, and usually white.
e. Heulandite : in rhomboidal prisms, with pearly basal cleavage, often trans¬
parent, and usually white.
Composition :
Analcime
Chahazite
Natrolite
Scolecite
Stilbite
Heu landite
— Silica, 54.6,
48.2,
47.4,
" 46.0,
" 57.6,
" 59.3,
Soda, 14.0,
Lime, 10.8,
Soda, 16.2,
Lime, 14.2,
8.9,
9.2,
Water, 8.1.
21.0.
9.5.
13.7.
16.3.
14.7.
Alumina, 23.2,
20.0,
26.9,
26.1,
16.3,
16.8,
They resemble the feldspars in having the same ratios between the protoxyds,
sesquioxyds, and silica, this ratio being—in Heulandite 1:1:4; in Stilbite
1:1:3; in Natrolite 1:1:2; in Chabazite 1:1:2$; in Analcime 1:1: 2$.
/. Prehnite is a species related to the zeolites, and similar in its modes of
occurrence. It is harder, the hardness being that of feldspar. The surface is
usually clustered, convex, and crystalline; the color, pale green to white;
translucent. G. = 2.8-3.0. Before the blowpipe, intumesces and melts. Com¬
position: Silica, 43.8, alumina, 24.8, lime, 27.1, water, 4.3.
69.
5. Carbonates. Sulphates.
(22.) Calcite, or Carbonate of Lime.—Crystals rhombohedral or
hexagonal, with perfect cleavage parallel to the faces of a rhombo-
hedron the obtuse angle between whose faces (or R on R, fig. 52 a)
is 105° 5/. Forms various, a few of which are shown in the figures.
Crystals often transparent; massive kinds granular, as in statuary-
marble, or opaque and earthy, as in common limestones. Colors,
CONSTITUENT MINERALS OF ROCKS.
63
from white to yellowish, reddish; grayish-brown to black when
impure. Easily scratched with a knife. G. = 2.5-2.8. Crystalline
varieties readily distinguished by the angle, 105° 5/, between the
cleavage-faces ; and all kinds by the low degree of hardness, ready
effervescence when touched with a drop of dilute muriatic acid, and
infusibility. When burnt, it becomes quicklime. Composition: Car¬
bonic acid, 44.0, lime, 56.0.
The same compound, carbonate of lime, occurs under a prismatic crystalline
form, and is then called Aragonite: it is easily recognized by the absence of the
rhombohedral cleavage, and also by means of polarized light. It is somewhat
harder than calcite. G. = 2.9-3.0. In shells the pearly part is Aragonite,
while the rest is usually calcite.
(23.) Magnesite.—Crystals rhombohedral or hexagonal, like calcite, with
the angle between two planes R 107° 29'; but usually massive, and often look¬
ing like porcelain biscuit. Harder than calcite. Color, white. G. = 2.8-3.
Infusible: no immediate effervescence when touched with dilute acid, though
dissolving when powdered and heated with acid. Composition: Carbonic acid,
52.4, magnesia, 47.6.
(24.) Dolomite.—Rhombohedral, as in calcite, with R on R = 106°
15/. Also massive, constituting much of the white architectural
marble, and some earthy limestones. G. = 2.8-3.0. Distinguished
from calcite by not affording effervescence when touched with
dilute acid, unless heated. It is a carbonate of magnesia and lime,
containing carbonate of lime, 54.4, carbonate of magnesia., 45.6.
(25.) Chalybite.—a carbonate of the protoxyd of iron, having the same
crystallization as carbonate of lime or calcite, but higher specific gravity (G.=
3.7-3.9), somewhat greater hardness, and a grayish or brownish color becoming
deep brown on exposure.
70. (26.) Gypsum.—Crystals as in the figures 54 and 55, an oblique
(monoclinic) prism, with very perfect cleavage in one direction,
affording large pearly plates, which bend in one direction and
Fig. 52.
Fig. 53.
64
LITHOLOGICAL GEOLOGY.
break in another, and are inelastic. Also fibrous, with satin lustre.
Also earthy, massive, of dull gray and other colors. "Very soft,
so as easily to be cut with a knife.
The white, compact kind is ala¬
baster. When heated, burns white
and crumbles, losing its water, and
becoming a powder, which is com¬
mon "plaster of Paris." Composition: Sulphuric acid, 46.51, lime,
32.56, water, 20.93.
(27.) Anhydrite.—The same in composition as gypsum, except that it con¬
tains no water. Crystals rectangular, with three distinct and nearly equal
cleavages, affording cubical and rectangular blocks, and thus easily distin¬
guished from those of gypsum. Color, white, grayish, bluish, and other pale
shades. Hardness near that of calcite. G. = 2.8-3.01. Before the blowpipe,
does not exfoliate like gypsum. Composition: Sulphuric acid, 58.8, lime, 41.2.
6. Additional mineral species.
71. (28.) Graphite, called also Plumbago or Black Lead. The lustre, soft¬
ness, and the tracing it leaves are well seen in the common "lead-pencil." The
structure is either foliated or granular; and sometimes it gives a slaty structure
to a rock. It is essentially pure carbon.
(29.) Pyrites (Iron Pyrites).—In cubes, the adjacent faces
of which are often striated at right angles with one another, as
in the annexed figure (56); also in other forms; also massive.
Color, pale brass-yellow. Hard enough to strike fire with
steel. G. = 4.8-5.1. Composition: Sulphur, 53.3, iron,
46.7.
(30.) Chalcopyrite (or Copper Pyrites).—Resembles iron
pyrites, but is of a deeper yellow color, much softer, being scratched with a
knife, and giving a dark-greenish powder, and when wet with nitric acid a
knife-blade put in the acid becomes coated with copper. Contains sulphur, 34.9,
copper, 34.6, iron, 30.5. There is also a gray sulpliuret of copper, called copper -
glance, which has a steel or iron lustre, and consists of sulphur, 20.2, copper, 79.8.
There is still another, which tarnishes readily, and is sometimes called horse¬
flesh ore, from the color of the tarnish, which consists of sulphur, 23.7, copper,
62.5, iron, 13.8.
(31.) Blende.—In crystals; also massive, cleavable, with a brilliant lustre ;
the lustre resinous ; the yellow and brown varieties look much like a resin,
and the black variety approaches metallic in lustre; a touch of the point i f a
knife affords a white or whitish scratch or powder. Blende is a sulpliuret of
zinc, containing sulphur 33, zinc 67.
(32.) Galena.—In cubic and other related crystalline forms, and breaking
readily by cleavage into small cubes; also massive and granular. Color, lead-
o-ray. Readily cut by a knife, although brittle. G. = 7.2-7.7. Galena is
the common lead-ore, a sulphuret of lead, consisting of sulphur, 13.4, lead, 86.6.
CONSTITUENT MINERALS OF ROCKS.
65
72. (33.) Hematite (or Specular Iron). A common iron-ore, having often a
high metallic lustre, though often also red and earthy. Powder deep red or
brownish red. Not attracted by the magnet. As hard as feldspar. Composi¬
tion: Oxygen, 30, iron, 70. Titanic iron (Ilmenite) resembles hematite closely,
but has a black powder, and contains titanium with the iron.
(34.) Magnetite (or Magnetic Iron-Ore). Crystals octahedrons, and some¬
times cubes or dodecahedrons. Iron-black. Powder black. Strongly attracted
by a magnet. G. = 4.9-5.2. Composition: Protoxyd of iron, 31.03, peroxyd
of iron, 68.97; or, Oxygen, 27.6, iron, 72.4.
(35.) Limonite (Hydrous Sesquioxyd of Iron).—In massive forms; often
also stalactitic and mamillary; black and imperfectly metallic in lustre, or
brown to yellowish-brown, and earthy. Powder yellowish-brown. G. =3.6-4.
Composition : Sesquioxyd of iron, 85.6, water, 14.4; or the same as hematite,
excepting the water. The color of the powder distinguishes this species, as well
as the magnetite, from hematite.
Hematite, Magnetite, and Limonite are the three most common ores of iron.
They are distinguished by the color of their powders.
73. (36.) Fluor Spar (Fluorid of Calcium). In cubes, octahedrons, and
other forms, with a perfect and easy cleavage on the angles of the cube ; also
massive, granular. Often transparent and glassy ; also translucent. Colors,
clear and handsome, blue, purple, yellow, reddish, white; sometimes banded;
receiving a high lustre when polished. When powdered coarsely and thrown
on a shovel heated to just below redness, it phosphoresces finely. Heated
with sulphuric acid, it gives out vapors which corrode glass. Composition :
Fluorine, 48.7, calcium, 51.3.
(37.) Barytes (or Heavy Spar, Sulphate of
Baryta). In tabular crystals (fig. 57), rect¬
angular or rhombic. Color, white, sometimes
yellowish, reddish. Remarkable for its weight.
G. = 4.3-4.7. Composition: a sulphate of
baryta = Sulphuric acid, 34.33, baryta, 65.67.
(38.) Apatite (Phosphate of Lime).—In
hexagonal prisms, often large; no good cleav¬
age; also massive. Color, sea-green, bluish-
to yellowish-white, often resembling beryl, but
much softer, being scratched with the point of
a knife. Transparent to opaque. G. = 3.25.
Composition: Phosphoric acid, 42.26, lime,
50.0, fluorine, 3.77, calcium, 3.97.
(39.) Clay.—Clay is not a simple mineral.
It is the material of such rocks as contain feldspar, ground up to an impal¬
pable powder. It is therefore often a mixture of finely-ground feldspar and
quartz, in which the former predominates, together usually with other ingre¬
dients derived from the rocks, as lime, magnesia, and oxyd of iron, in small
or large proportions. Clay, when baked, makes brick or pottery; and, if it
contains oxyd of iron, it burns red, the oxyd of iron losing in the process the
water which was in combination with it.
6
Fig. 57.
66
L1TH0L0GICAL GEOLOGY.
Clays which have a peculiar unctuous feel are more or less pure chemical
compounds, consisting of silica, alumina, and water, and related to the mineral
species Halloysite. Halloysite consists of silica, 41.5, alumina, 34.4, water, 24.1.
It results from the decomposition of feldspar. Kaolin, or porcelain clay, is an¬
other product of the decomposition of feldspar, consisting usually of silica, 45,
alumina, 40, water, 15. It is a fine white clay, and is used for the finest porce¬
lain. Potter's clay contains more or less of these ingredients, kaolin, halloy¬
site, or the allied species.
74. The materials of organic origin—that is, those derived from
plants or animals—may be arranged in four groups.
(1.) The calcareous, or those of which limestones have been formed:
namely, corals, corallines, shells, crinoids, etc. The specific gravity
of corals is 2.4-2.82; of shells, 2.4-2.8G,— the highest from a
Chama (Silliman, Jr.).
(2.) The siliceous, or those which have contributed to the silica
of rocks, and may have originated flints, namely, (a) the micro¬
scopic siliceous shields of the infusoria called diatoms, which are
now regarded as plants; (6) the microscopic siliceous spicula
of sponges.
(3.) The phosphatic, or those which have contributed phosphates,
especially the phosphate of lime, as bones, excrements, and a few shells
related to the Lingula. Fossil excrements are called coprolites; or
those of birds when in large accumulations, guano.
The remains of animals have also afforded traces of fluorine.
(4.) The carbonaceous, or those which have afforded coal and resin,
as plants.
Besides these, there is a fifth kind, though of little importance
geologically, viz., the animal tissues themselves. Only in a few
cases do any of these tissues remain in fossils, except in some kinds
of the later geological epochs. These tissues contain traces of phos¬
phates and fluorids.
75. (1.) Calcareous.—The following are a few analyses: 1 and 2, corals,
Madrepora palmata and Astraea Orion, by B. Silliman, Jr.; 3, a shell, by the
same :—
7. Materials of organic origin.
Carbonate of lime 94.81
Phosphate and fluorids. 0.45
Sulphate of lime
Madrepore.
Astrasa.
96.47
Shell (Chama).
97.00
Oyster-shell.
93.9
r
0.5
1.4
2.60
Earthy matters 0.30
Organic tissues 4.45
Carbonate of magnesia
0.30
4.45
2.73
0.40
3.9
0.3
CONSTITUENT MINERALS OF ROCKS.
67
In many shells the inner pearly layer consists of carbonate of lime in the
condition of Aragonite (§ 69) ; while the outer (or the whole, if no part is
pearly) is usually common carbonate of lime, or calcite. The spines of Echini
are calcite.
In corals of the genus 3fillepora, according to Damour, there is, besides car¬
bonate of lime, some carbonate of magnesia, amounting in one species to 19
per cent., while but little in others. These corals have been shown by Agassiz
to be related to the Medusse, and not to the ordinary polyps. Forchhammer
found 6.36 per cent, of carbonate of magnesia in the Isis nobilis, and 2.1 per
cent in the Corallium nobile, or precious coral of the Mediterranean.
The Nullipores and Corallines are vegetation having the power of secreting
lime, like the coral animals. The shells of Rhizopods (called also Polythalamia
and Foraminifera) are calcareous.
The shell of a lobster (Palinurus) afforded Fremy, Carbonate of lime, 49.0,
phosphate of lime, 6.7, organic substance, 44.3.
76. (2.) Siliceous.—The organic Silica is, in part at least, in that condition
characterizing opal (p. 55.) The mineral Randanite is a kind of opal, made of
infusorial remains.
77. (3.) Phosphatic.—Analyses of bones: 1,2, human bones, according to
Frerichs; 3, fish (Haddock), according to Dumenil; 4, shark (Squalus cornu-
bicus), according to Marchand: 5, fossil bear, id.
* 1. 2. 3. 4. 5.
Phosphate of lime 50.24 59.50 55.26 32.46 62.11
Carbonate of lime 11.70 9.46 6.16 ) 13.24
Sulphate of lime J 12 25
Organic substance 38.22 30.94 37.63 58.07 4.20
Traces of soda, etc 1.22 3.80
Fluorid of calcium 1.20 2.12
Phosphate of magnesia 1.03 0.50
In No. 4 a little silica and alumina are included with the fluorid. No. 5 con¬
tains also silica 2.12, and oxyds of iron and manganese, etc., 3.46.
The enamel of teeth contains 85 to 90 per cent, of phosphate of lime, 2 to 5 of
carbonate of lime, and 5 to 10 of organic matters.
Fish-scales from a Lepidosteus afforded Fremy 40 per cent, of organic sub¬
stance, 51.8 of phosphate of lime, 7.6 of phosphate of magnesia, and 4.0 of phos¬
phate of lime. Other fish-scales contained but a trace of the magnesia-phosphate
and more of organic matters.
Phosphatic nodules, possibly coprolitic, in the Lower Silurian rocks of Ca¬
nada (on river Ouelle) afforded T. S. Hunt (see Am. Jour. Sci. [2] xv. and xvii.),
in one case, phosphate of lime, 40.34, carbonate of lime, with fluorid, 5.14, car¬
bonate of magnesia, 9.70, peroxyd of iron, with a little alumina, 12.62, sand,
25.44, moisture, 2.13 = 95.37. In a hollow cylindrical body from the same
region there were 67.53 per cent, of phosphate.
Analyses op Coprolites (fossil excrements).—Nos. 1 and 2 by Gregory and
AValker; 3 and 4 by Connell; 5 by Quadrat; 6 by Rochleder (a coprolite from
the Permian).
68
LITHOLOGICAL GEOLOGY.
1.
2.
3.
4.
5.
6.
Burdie-
Fife-
Burdie-
Burdie-
Kosch-
Oberlan-
house.
shire.
house.
house.
titz.
genau.
Phosphate of lime
.. 9.58
63.60
85.08
83.31
50.89
15.25
Carbonate of lime
.. 61.00
24.25
10.78
15.11
32.22
4-57
Carbonate of magnesia .
.. 13.57
2.89
2.75
Sesquioxyd of iron
.. 6.40
trace
2.08
6.42
Silica
' I 4.13
trace
0.34
0.29
0.14
Organic material
. J
3.38
3.95
1.47
7.38
74.03
5.33
3.33
Lime of organic part
1.44
1.96
100.01
97.45
100.15
100.18
99.13
100.00
Analysis of the shell of the recent Lingula ovalis, according to T. S. Hunt
(Am. Jour. Sci. [2] xvii. 237):—Phosphate of lime, 85.79, carbonate of lime,
11.75, magnesia, 2.80 = 100.34,—or very near the composition of bones. The
shell of species of Orbicula and Conularia was found to have the same com¬
position.
78. (4.) Carbonaceous.—Mineral coal is essentially carbon, combined usually
with bitumen or some kind of bituminous substanpe, and more or less earthy
substance (the ash). The varieties are—
A. Anthracite.—Containing no bituminous matter. A hard, lustrous coal,
breaking with a conchoidal fracture and clean surface, and burning with very
little flame, as the coal of Lehigh, Wyoming, and other places of central Penn¬
sylvania, also that of Rhode Island.
B. Bituminous coal.—Containing bituminous substances, and therefore burn¬
ing with a bright flame. Softer than anthracite, less lustrous, often looking a
little pitchy. The amount of bituminous substances varies from 10 to 60 per
cent., and occasionally reaches 72 per cent. Among the kinds of bituminous
coal there are—
a. Caking Coal. The common variety when caking in the fire from the
exuding bitumen.
h. Cannel Coal. A very compact coal, with an even texture, smooth, clean,
and nearly dull surface, and a conchoidal fracture. The dull lustre gives it the
aspect often of being impure, when not so. The proportion of bitumen is
large.
c. Aephaltic Coal. A black and very lustrous coal, looking like pure asphaltum
or mineral pitch. From the Albert mine, Nova Scotia. Four per cent, soluble
in ether, and thirty in turpentine.
C. Lignite is a black or brownish-black coal, having an empyreumatic odor
when burned, and usually retaining something of the texture of the original
wood. It is sometimes called brown coal. It belongs to secondary and more
modern deposits. Jet is a very compact, black, and lustrous lignite. Peat is an
imperfect coal, made mainly from mosses in swamps after a long burial and a
partial alteration of the material. It is sometimes entirely converted into
eoal.
CONSTITUENT MINERALS OF ROCKS.
69
The composition of mineral coal varies much. The following are the results
of some analyses :—
Volatile
combustible Fixed
matter. carbon. Ash.
Anthracites of Pennsylvania 3.84 87.45 7.37 = 98.66 Johnson.
Bituminous, Pittsburg 32.95 64.72 2.31 = 99.98 Johnson.
La Salle, Illinois 39.17 54.19 6.64 = 100 Whitney.
Cannel, Boghead, Scotland 66.35 30.88 2.77 = 100 Silliman.
" Breckenridge co., Kentucky 55.7-71.7 28.3-44.3 7.-12.30 Peter.
" Wigan, Lancashire,England 50.18 46.42 3.40 = 100 Heddle.
Asphaltic coal 61.74 36.04 2.22 = 100 Silliman.
Ultimate analyses, to determine the proportions of the elements, have given—
the ashes excluded—
Carbon. Hydrogen. Oxygen. Nitrogen.
Anthracite 94.05 1.75 4.20 0.00 Regnault.
Bituminous 82.2 5.5 12.3 0.00 Bischof.
Cannel, Boghead 80.49 11.24 6.73 0.87 Peter.
Cannel, Breckenridge ... 82.36 7.84 7.05 2.75 Peter.
Asphaltic coal 82.67 9.14 8.19 Wetherill.
Lignite 72.3 5.3 22.4 Regnault.
Peat, Provincetown 60.1 6.1 33.8 Yaux.
Peat coal, Westphalia... 80.7 4.1 15.2 Baer.
The ashes consist mostly of silica and alumina, in the ratio of 1 of the former
to 1 or 2 of the latter, with a trace of lime and magnesia; and, in those coals
which afford a red ash, some oxyd of iron, often derived from pyrites mixed
with the coal. In good coals, the ash does not exceed 10 per cent., of which, as
an average, 2 to 4 might be silica, 4 to 7 alumina, and £ each lime and magnesia,
or oxyd of iron.
Resins of several kinds occur in some coal-beds, especially in those of tertiary
age. Amber is of this kind. They come from the ancient trees, but have been
altered in the course of their long burial.
Fossils.—From the above account of the composition of the hard
parts of organic beings, their influence on the composition of rocks
is readily inferred.
But the fossils themselves seldom retain completely, even in the
case of such stony secretions as shells and corals, their original
constitution. There is usually a loss of the organic matter. There
is often a further change of the carbonate of lime into a new mole¬
cular condition, manifest in the fact that the fossil has the oblique
cleavage of calcite; and in this change there is a loss of part or all
of the phosphate or fluorid. There is sometimes, again, a change to
dolomite, in which the carbonate of lime becomes a carbonate of
lime and magnesia. In other cases, of very common occurrence, all
the fossils of a rock, whether limestone or sandstone, are changed
70
LITHOLOGICAL GEOLOGY.
to silica (quartz) by a silicifying process. Silicified trunks of trees,
as well as shells, occur of all geological ages. In some cases fossils
have been altered to an oxyd of iron, or to the sulphuret of iron
(pyrites).
In many cases the fossils are entirely dissolved out by percolating
• waters, leaving the rock full of cavities. This happens especially
in sandstones, through which waters percolate easily, and not in
clays, which preserve well the fossils committed to them; and
hence sands, gravel, conglomerates, quartzose sandstones, contain
few organic remains.
3. KINDS OF ROCKS.
79. General subdivisions.—Rocks are conveniently divided into
fragmental and crystalline.
1. Fragmental.—Rocks that are made up of pebbles, sand, or clay,
either deposited as the sediment of moving waters or formed and
accumulated through other means:—as ordinary conglomerates, sand¬
stones, clay-rocks, tufas, and some limestones. The larger part of the
rocks here included are made of sedimentary material, and are
commonly called sedimentary rocks. They are stratified rocks,—that
is, consist of layers spread out one over another. Many of them
are fossiliferous rocks, or contain fossils.
2. Crystalline.—Rocks that have a crystalline instead of a frag¬
mental character. The grains, when large enough to be visible,
are crystalline grains, and not water-worn particles or fragments of
other rocks. Examples, granite, mica schist, basalt.
The crystalline rocks may have been crystallized,—
a. From fusion, like lava or basalt, when they are called igneous rocks.
I. From solution, as with some limestones.
c. Through long-continued heat without fusion. By this last
method sedimentary beds have been altered into granite, gneiss,
or mica schist, and compact limestone into statuary-marble.
As, in such cases, a bed originally sedimentary has been meta¬
morphosed into a crystalline one, rocks of this altered kind are
called metamorphic rocks.
In the following descriptions a separate subdivision is made of
the calcareous rocks or limestones, which are mostly sedimentary in
original accumulation, but generally lose that appearance as they
solidify.
80. Characteristics of Rocks.—Independently of the characters
above mentioned, rocks differ in kinds:—
KINDS OF ROCKS.
71
a. First. As to structure : whether—
Massive, like sandstone, or granite, breaking one way about as easily as
another.
Schistose or laminated, breaking into slabs, like flagging-stone; schistose is
usually restricted to the crystalline rocks, like gneiss and mica schist.
Slaty, breaking into thin and even plates, like roofing-slate.
Shaly, breaking unevenly into plates, and fragile, like the slate or shale of the
coal formation, the Utica slate, etc.
Concretionary, having the form of, or containing, spheroidal concretions;
some varieties are also called globuliferous, when the concretions are isolated
globules and evenly distributed through the texture of a rock.
b. Second. As to hardness and firmness :
Compact, or well consolidated.
Friable, or crumbling in the fingers.
Porous, so loose or open in texture as to absorb moisture readily.
Uncompacted, or like loose earth.
Flinty, very hard, and breaking with a smooth surface like flint.
c. Third. As to the rock or mineral nature of the constituents:
Granitic, like granite, or made of granite materials.
Siliceous, consisting mainly of quartz.
Quartzose, same as siliceous; but also consisting largely of quartz in grains,
—a quality expressed by arenaceous, when the rock is mainly made up of quartz
grains.
Micaceous, characterized eminently by the presence of mica.
Calcareous, of the nature of limestone, or containing considerable carbonate
of lime, as a calcareous rock, a calcareous mica schist.
Argillaceous, having a clayey nature or constitution, or containing much clay,
as shale is argillaceous, a sandstone may be argillaceous.
Ferruginous, containing oxyd of iron; sometimes having a red, brownish-red,
or brownish-yellow color in consequence of the disseminated oxyd of iron ;
sometimes containing the ore in plates or masses of a metallic lustre.
Pyritiferous, containing pyrites (p. 64) disseminated through the mass, either
in cubic crystals, or in grains or masses.
Basaltic, made of material derived from basalt : also like basalt.
Pumiceous, made of pumice.
Gametiferous, containing garnets.
So, also, staurotidiferous, containing staurotide; anthophyllitic, containing
acicular hornblende of the variety anthophyllite.
Sedimentary rocks differ, further (d), as to the mechanical condition
of the constituents : whether—
(«) Rounded stones or pebbles; or (b) angular stones; or (c) sand; or
(d) clay.
Crystalline rocks differ, further,—
72
LITHOLOGICAL GEOLOGY.
e. As to the number and kinds of mineral constituents, as explained
beyond.
/. As to the kind of crystalline aggregation or structure:
Granular (phanero-crystalline, or distinctly crystalline), which may be either
coarse granular, as in granite and much architectural marble, or fine granular,
as in some statuary-marble.
Gnjptocrystalline, or concealed crystalline, as in flint, no particles being
distinct.
Granitoid, having each of the mineral constituents separately crystallized
and distinct, as in granite, syenite, diorite.
Other terms bearing on structure are
as follow:—
Porphyritic.—Having the feldspar in
distinct crystals through the mass of
the rock, or speckling it with spots
of white or a light color that are often
rectangular or nearly so (fig. 58).
The term porphyritic is sometimes applied
also where hornblende or pyroxene is in dis¬
tinct crystals in the rock-mass, the rock in this case being described as por¬
phyritic with hornblende or with pyroxene.
The feldspar crystals are often double or twin crystals, as shown by a line of
division through the middle (see fig. 58). Granite, diorite, dolerite, and lavas,
as well as porphyry, are sometimes porphyritic, and the feldspar crystals might
be very large or very small.
Homogeneous, having the mineral ingredients not separately dis¬
tinguishable, but forming a homogeneous mass, granular or other¬
wise, like most trap, or dolerite and argillite.
Amygdaloidal (from amygdalum, an almond). Having numerous sphe¬
roidal or almond-shaped cavities, like some trap, dolerite, basalt, the cavities
filled with minerals foreign to the rock, such as quartz, calcite, and the
zeolites.
Scoriaceous.—Slag-like, very open, cellular, or inflated, like the scoria of a
volcano or slag of a furnace.
It should further be observed that a rock—
When Quartz predominates, is hard and often gritty. G. = 2.5-2.8.
Feldspar—hard, usually light-colored. G. =2.5-2.8. Either cleavably
crystalline or cryptocrystalline.
Hornblende and Pyroxene—hard, usually dark-green to black; heavy. G. =
2.8-3.6. Often tough.
Mica—slaty, glistening with mica scales, not very hard, not greasy to the
touch. G. = 2.5-2.8.
Tale—often slaty, somewhat glistening, a greenish color, grayish, brownish,
not very hard ; a greasy feel. G. = 2.4-2.7.
Fig. 58.
kinds of rocks.
73
Chlorite—often slaty, soft, an olive-green color; but little greasy to the touch.
G. = 2.7-3.2.
Serpentine—massive, rather soft, dark or light green; but little greasy to the
touch. G. = 2.4—2.6.
Carbonate of lime—moderately soft, effervescing readily with acids. G. =
2.5-2.8. Usually massive; white to black.
Carbonate of lime and magnesia, or dolomite—like the preceding; but not effer¬
vescing readily with cold acid.
An easy effervescence with dilute muriatic acid indicates the presence of car¬
bonate of lime.
1. Fragmental Rocks, exclusive of Limestones.
81. (1.) Conglomerate.—A rock made up of pebbles or fragments
of rocks of any kind. (a) If the pebbles are rounded, the conglo¬
merate is a pudding-stone; (b) if angular, a breccia.
Conglomerates are named, according to their constituents,
siliceous or quartzose, granitic, calcareous, porphyritic, pumiceous, etc.,
using these terms as already explained. The cementing-ingre-
dient may be calcareous, siliceous, ferruginous, and occasionally of
other kinds.
(2.) Grit, Grit-Rock.—A hard, gritty rock, consisting of sand and
small pebbles, called also millstone grit and grindstone grit, because used
sometimes for grindstones. Also applied to a hard, gritty sand¬
stone, as the paving-stone of the Hudson River.
(3.) Sandstone.—A rock made from sand agglutinated. There
are siliceous, granitic, porphyritic, basaltic, or calcareous sandstones,
according to the nature of the material. But the calcareous is
called calcareous sand-rock rather than sandstone. There are also
compact sandstone, friable sandstone, ferruginous sandstone, concretionary
sandstone.
Micaceous sandstone.-—A sandstone glistening with scales of mica.
Argillaceous sandstone.—Containing much clay with the sand; also called
shaly sandstone, when thin-laminated in structure.
Marly sandstone.—Containing carbonate of lime, so as to effervesce when
treated with dilute acid.
Flexible sandstone.—See Itacolumite, § 88.
(4.) Shale.—A soft, fragile rock, made from clay, and having an
uneven slaty structure as explained on page 71. Shales are gray to
black in color, and sometimes of dull greenish, purplish, reddish,
and other shades.
Among the varieties there are—
Bituminous shale.—Impregnated with bitumen, or yielding the odor of bitumen
when struck.
74
LITHOLOGICAL GEOLOGY.
Coaly shale.—Containing coaly impressions or impregnations.
Alum shale.—Impregnated with alum or pyrites,—usually a crumbling rock.
The alum proceeds from the alteration of pyrites.
(5.) Tufa. Pozzuolana.—Tufa is an earthy rock, not very hard,
made from comminuted volcanic rocks, or volcanic cinder, more
or less decomposed, and often forming beds of great extent. It is
usually of a yellowish-brown, gray, or brown color.
The color varies with the nature of the material:—basaltic rocks or lavas
produce brownish colors (the color is owing to the hydrous oxyd of iron
present, derived from the pyroxene or magnetic iron of the original rock,
altered by the action of water); feldspathic lavas produce light-grayish colors.
Pumiceous tufa, which belongs to the latter division, consists mainly of pumice
in grains and fragments, more or less altered.
Pozzuolana is a kind of light-colored tufa, found in Italy, near Rome and
elsewhere, and used for making an hydraulic cement.
Wacke.—An earthy, dark-brownish rock, resembling an earthy trap or do-
lerite, and usually made up of trappean or doleritic material compacted into a
rock which is rather soft.
(G.) Sand. Gravel.—-Sand is comminuted rock of any kind; but
common sand is mainly comminuted quartz, or quartz and feldspar,
while gravel is the same mixed with pebbles or stones. Occasionally
sand contains scales of mica and has a glistening lustre. Volcanic
sand, or peperino, is sand of volcanic origin, either the "cinders" or
" ashes" (comminuted lava) formed by the process of ejection, or
from lava rocks otherwise comminuted.
(7.) Alluvium. Silt. Till.—Alluvium is the earthy deposit made by
running streams, especially during times of flood. It constitutes the
flats on either side of the stream, and is usually in thin layers, vary¬
ing in fineness or coarseness, being the result of successive deposi¬
tions. Silt is the same material deposited in bays or harbors, where
it forms the muddy bottoms and shores. Till is an earthy deposit,
coarse or fine, following the courses of valleys or streams, like allu¬
vium, but without division into thin layers, although in very thick
deposits. The till of the Alpine valleys is formed by the action of
glaciers. Detritus (from the Latin for worn) is a general term ap¬
plied to earth, sand, alluvium, and the like.
2. Metamorphic or Crystalline Rocks, not Calcareous.
82. Metamorphic rocks are made from the sedimentary rocks
above enumerated by some crystallizing process, and vary exceed¬
ingly in the perfection of the crystallization they have undergone.
Granite stands at one end of the series, and hard sandstones called
KINDS OF ROCKS.
75
quartzite, hard slates like roofing-slate, and partially crystallized
limestones, at the other; so that a distinct line between them and
the sedimentary beds cannot always be drawn. They are some¬
times called plutonic rocks, to distinguish them from the true
igneous rocks.
The common ingredients are quartz, feldspar of different kinds,
mica, hornblende, pyroxene, talc, epulote, chlorite, serpentine; to which
garnet, andalusite, staurotide, tourmaline, topaz, graphite, may be added as
characterizing a number of varieties. The rocks are aggregates in
general of two or more of the above-mentioned minerals; and, as
the proportions may vary indefinitely, the kinds of rocks are not
in all cases well defined; they graduate into one another through
imperceptible shades.
Metamorphic rocks may, for the most part, be distributed into
three series parallel with one another. These are the mica-bearing
series, containing granite, gneiss, mica schist, etc.; the hornblendic,
characterized by the presence of hornblende or the allied pyroxene,
as in syenite, hornblendic gneiss, etc.; and the hydrous magnesian
series, containing talc, chlorite, and serpentine rocks. Besides
these, there are other groups, which with the foregoing are de¬
scribed beyond in the following order:—
1. Mica-bearing series.
2. Hornblendic series.
3. Feldspathie, epidotic, and garnet rocks, having the mass or body of the
rock compact (cryptocrystalline).
4. Hydrous magnesian series.
5. Hydrous aluminous series, or rocks consisting essentially of agalmatolite
or pyrophyllite.
6. Quartz rocks.
7. Iron-ore rocks.
1. The Mica-bearing Series.
The mica-bearing series commences with granite, the most highly
crystalline, and descends through gneiss and mica schist to argillite or
roofing-slate, and also to quartzite, which is but little removed from a
sandstone. Quartz is a constant ingredient, as well as mica. The
series branches off into crystalline feldspathie rocks like granulite,
containing little or no mica. The specific gravity is between 2.4
and 2.8.
83. (1.) Granite.—A granular crystalline rock, consisting of
quartz, feldspar, and mica, having no appearance of layers in the
arrangement of the mica or other ingredients. The mica is in
scales, usually white, black, or brownish, easily separable into
thinner elastic scales by means of the point of a knife ; the quartz
70
LITIIOLOGICAL GEOLOGY.
is usually grayish white, glassy, and without any appearance of cleavage ;
the feldspar is commonly whitish or flesh-colored, less glassy than
the quartz, and showing a flat, polished cleavage-surface in one or
two directions.
а. Common Granite—X granite in which the feldspar is common feldspar
(the species orthoclase, $ 55), or potash-feldspar, the most common kind. The
color is grayish or flesh-colored, according as this feldspar is white or reddish.
The texture varies from a fine and even-grained to a coarse granite in which the
mica, feldspar, and quartz—especially the two former—are in large crystalline
masses. Porphyritic granite has the feldspar distributed in distinct crystals,
which appear as rectangular whitish blotches on a surface of fracture. Syenitic
granite contains black scales or grains of hornblende besides the mica. Ifiascite
consists of cleavable white feldspar (orthoclase), black mica, and grayish or
yellowish-white elseolite, with some hornblende, and occasionally albite or quartz.
It is associated with syenite.
б. Alhitic Granite.—A granite in which part or all of the feldspar is albite, or
soda-feldspar (§ 55, b). This feldspar is usually white, and when both albite
and orthoclase are present, the latter may often be distinguished by having a
more grayish or reddish color, and by not having the cleavage-surface finely
striated in one direction, like albite.
(2.) Pegmatite, or Graphic Granite.—A very coarse granitic rock, consisting
of common feldspar and quartz with
but little whitish mica; in the graphic
variety the quartz is distributed
through the feldspar in forms look¬
ing like Oriental characters (fig. 59).
(3.) Granulite. — A fine-grained
granitic rock, consisting mainly of
granular feldspar with little quartz,
and often imperfectly schistose in
structure from the arrangement of
the quartz. It is also called eurite
and leptynite ; and the flinty kind, petrosilex. (See beyond, § 85.)
(4.) Gneiss.—Like granite, but with the mica more or less dis¬
tinctly in layers. A gneissoid granite is a rock intermediate between
granite and gneiss, or showing some tendency to the gneiss struc¬
ture. As the mica is in scales as well as easily cleavable, a gneiss
rock breaks most readily in the direction of the mica layers,—
thus affording slabs. This structure, causing a tendency to break
into slabs, is called a schistose structure.
Porphyritic Gneiss has distinct feldspar crystals disseminated through it, like
porphyritic granite. Gneiss may abound in garnets, or be garnetiferous; or
contain an excess of mica, when it is called micaceous gneiss; or much epidote,
becoming an epidotic gneiss. Gneiss graduates into—
(5.) Mica Schist.—The same constituents as granite and gneiss,
%11
f
ii /. ^
HIT ^
//? A <'
KINDS OF ROCKS.
77
but with less feldspar and much more mica,—therefore glistening in
lustre ; slaty, or very schistose, in structure, breaking into thin slabs
or plates ; often friable, or wearing easily.
Mica schist often abounds in garnets, staurotide (§ 01), or tourma¬
line (§ 63).
The variety plumbaginous schist contains plumbago (p. 64) in its layers. Cal¬
careous mica schist contains, disseminated through it, carbonate of lime or cal-
cite. Talcose mica schist contains talc as well as mica. Hornblendic mica schist
contains black or greenish-black crystals of hornblende. Anthophyllitic schist
is related to the last, but the acicular crystals are of the brown variety of horn¬
blende called anthophyllite. Concretionary mica schist is a variety containing
concretions: the concretions may consist of feldspar and contain garnets; or
of mica and feldspar, etc. Specular schist is a variety in which the mica is
replaced to a great extent by micaceous or lamellar specular iron. It may be
connected either with mica schist or talcose schist.
(6.) Argillite, or Clay-Slate, Roofing-Slate.—Mica slate gra¬
duates into slates in which there is no distinct crystallization and
even the mica is not apparent. This fine-grained slate-rock is
ordinary roofing-slate and writing-slate, and occurs of bluish, pur¬
plish, red, and other colors, to black.
Argillite often contains andalusite ($ 60) running through it in
prismatic crystals seldom smaller than a goose-quill, and one or more
inches long. It also occasionally contains garnet, tourmaline, staurotide,
and ottrelite,—the last a mica-like though brittle mineral, imbedded
in small scales spangling the rock, as at Bellingham, Massachusetts.
The ottrelite has been called phyllite. The more glistening kinds
of slate sometimes contain mica in distinct but minute scales, or
have a sort of micaceous surface.
2. Hornblendic Series.
84. The hornblendic series commences in a granite-like species
(called syenite) containing quartz and feldspar along with hornblende
in place of mica. Hornblende is not so cleavable into leaves as
mica, and is brittle instead of elastic. It is also tough and heavy;
and hence hornblende rocks are generally tough and heavy, the
specific gravity between 2.9 and 3.5. From syenite the series runs
down through syenitic gneiss to hornblendic schist and hornblende
rock; then to rocks of very even texture and compactness, called
diabase and aphanite, the last like hornstone in fracture and surface.
The rocks above, following syenitic gneiss and some of the schists,
contain no quartz.
There is another related series, in which the rock contains hy-
persthene or diallage instead of hornblende, and quartz is mostly
78
LITHOLOGICAL GEOLOGY.
or wholly wanting. It commences in the granite-like hypcrite,
consisting of crystallized feldspar (usually labradorite) and liyper-
sthene. It passes into the tough and compact euphotide.
The hornblendic series blends laterally with the magnesian series, especially
through the ehloritic rocks of the latter, chlorite being near hornblende and
pyroxene in composition, though containing water. It also blends with the
mica series through granites and schists that contain both hornblende and mica.
Through the pyroxenic varieties it also passes into the igneous series.
(1.) Syenite.—Resembles granite, but contains in place of mica
the mineral hornblende, which is in cleavable grains and either black
or greenish black in color. The feldspar may be orthoclase or oligo-
clase, and sometimes the quartz is nearly wanting.
(2.) IIyperite.—Granite-like in texture, and of rather dark color,
consisting of cleavable labradorite ($ 55, d, usually dark and dull in
color, either grayish, reddish, or brownish, with bright-colored
internal reflections) and hypersthene (a lamellar cleavable variety of
pyroxene, $ 05 [14] ). A common rock in the Azoic of northern
New York and Canada.
(3.) Diorite, or Greenstone.—Resembles sj'enite in appearance and granular
crystalline texture, but contains little or no quartz : it consists of hornblende
and albite or oligoclase (a triclinic feldspar). The rock is therefore whitish,
speckled with black or greenish black. It is very tough. Sp. gr. 2.7-2.9. Gra¬
duates into a compact cryptocrystalline rock of a whitish, grayish, or greenish
color.
Porphyritic diorite has the feldspar in distinct imbedded crystals. Dioritic
schist is a diorite rock containing some mica and having a schistose structure.
(4.) Hornblendic Gneiss.—-Resembles gneiss in schistose structure,
but contains hornblende in place of mica. Zircon-syenite is a syenite
or hornblendic gneiss containing zircon with its other constituents.
(5.) Hornblendic Schist.—A schistose rock consisting mainly of greenish-
black hornblende with some feldspar; another variety, of hornblende and quartz;
another is nearly pure hornblende ; another contains epidote, and is therefore an
epidotic hornblendic schist.
(6.) Hornblende Rock.—A very tough, granular, crystalline rock, consisting
of hornblende, and hardly schistose in structure. Color, greenish-black to black.
(7.) Actinolite Rock.—A tough rock made of interlacing fibres of actinolite.
Color, grayish green. A variety from St. Francois, Canada, afforded T. S. Hunt
(Logan's Report for 1853-56, p. 445)—Silica, 52.30, magnesia, 21.50, protoxyd
of iron, 6.75, lime, 15.00, alumina, 1.30, oxyd of nickel, a trace, water, 3.10 =
99.95.
(8.) Pyroxenite (Cherzolite, Augite Rock).—Coarse or fine granular pyroxene
rock, consisting of granular pyroxene of a green, grayish green, to brown color,
often streaked or clouded with darker or lighter shades of color. Often con¬
tains, or is associated with, quartz, talc, steatite, and calcite.
KINDS OP ROCKS.
79
(9.) Diabase.—A massive hornblende rock, for the most part fine-grained in
texture, having a grayish-green to greenish-black color. It is like diorite in
composition, except that the feldspar is less abundant and is either labradorite
or oligoclase.
(10.) Aphanite.—Aphanite consists mainly of hornblende, with some feld¬
spar, and differs from the above in having a very compact or even a flinty
appearance. Color, grayish green, greenish white, or gray. It has been called
horn-rock.
Aphanite is sometimes slaty in structure, making an aphanitic slate. This rock
in the hornblendic series corresponds to argillite in the mica-bearing series. It
is distinguished from argillite by its greater specific gravity.
3. Feldspathic, Epidotic, and Garnet Rocks having the mass or base compact
(cryptocrystalline).
85. These feldspathic rocks may be simply feldspathic, or the base may be
partly hornblendic or quartzose. When they contain hornblende, garnet, or
epidote, it is apparent in the higher specific gravity. (1.) Some of the light-
colored rocks included are translucent and very tough, and contain grass-green
diallage (called also smaragdite) inlaminm; these are called euphotides: they
consist of feldspar, hornblende, epidote, or garnet. (2.) Others are opaque
and often dark-colored, and usually contain crystals of feldspar disseminated
through the mass; these are porphyries, or porphyroid rocks: they consist
mainly of feldspar. (3.) The rocks consisting of the base of the euphotides
without the diallage are called petrosilex.
a. Porphyroid Rocks.
(1.) Porphyrine.—Opaque, or nearly so. Colors, white, brown, red. In lustre
and fracture much resembling jasper, from which it differs in being fusible
before the blowpipe. Consists of feldspar: sometimes quartzose.
(2.) Feldspar-Porphyry.—Same as the last, with disseminated crystals of
feldspar.
A quartzose variety of feldspar-porphyry has the base consisting of feldspar
with some quartz. A variety of this kind occurs in eastern Massachusetts near
Lynn. Crystals of quartz as well as feldspar are distributed through the mass.
Colors, brownish-red and purplish. Specific gravity, 2.606.
(3.) Hornblendic Porphyry (Diabase Porphyry).—The antique green por¬
phyry of Greece (southern Morea) is here included. Specific gravity, 2.91-2.932.
Color, dark green; disseminated feldspar crystals, large, greenish white. Com¬
position of the base: Silica, 53.55, alumina, 19.43, protoxyd of iron, 7.55, prot-
oxyd of manganese, 0.85, lime, 8.02, magnesia and alkali, 7.93, water, 2.67. The
iron and magnesia indicate the presence of hornblende or pyroxene.
Porcelanite, or Porcelain-Jasper.—A baked clay, having the fracture of flint
and a gray to red color: it is somewhat fusible before the blowpipe, and thus
differs from jasper. Formed by the baking of clay-beds through the heat from
intrusive igneous dikes. Such clay-beds are sometimes baked to a distance
of thirty or forty rods from the dike.
80
LITHOLOGICAL GEOLOGY.
b. Petrosilex.
(1.) Orthoclase-Petrosilex.—Color, whitish, greenish; lustre somewhat
waxy, dull; specific gravity, 2.6-2.7. A greenish-gray specimen from Brittany
afforded Berthier—Silica, 75.4, alumina, 15.5, potash, 3.8, magnesia, 1.4, oxyd of
iron, 1.2,—whence it consists of orthoelase, feldspar, and some quartz.
(2.) Albite-Petrosilex.—Similar to the preceding. A variety from Orford,
Canada, afforded T. S. Hunt (Logan's Report for 1853-56)—Silica, 78.55,
alumina, 11.81, soda, 4.42, potash, 1.93, lime, 0.84, magnesia, 0.77, protoxyd of
iron, 0.72, loss by ignition, 0.90 = 99.94. This rock graduates into feldspar-
euphotide.
(3.) Diorite-Petrosilex.—Compact diorite, and consisting, therefore, of
albite and hornblende. Color, grayish white, greenish white. Occurs in Orford,
Canada (T. S. Hunt, Logan's Report, 1853-56).
(4.) Garnet-Petrosilex.—A pure, compact, garnet rock, of a whitish color,
with spots of disseminated serpentine. Specific gravity, 3.3-3.5. Composition of
the base of this rock, from Orford, Canada, according to T. S. Hunt—Silica, 38.60,
alumina, 22.71, lime, 34.83, magnesia, 0.49, oxyd of iron and manganese, 1.60,
soda (with a trace of potash), 0.47, loss by ignition, 1.10 = 99.80. Specific gravity,
3.522-3.536. It is exceedingly hard and tough. Graduates into garnet-
euphotide. A similar rock occurs at St. Frangois, Canada.
c. Euphotides.
(1.) Feldspar-Euphotide.—Tough compact, light-green or grayish, con¬
sisting of a minutely-granular feldspathic base with disseminated diallage or
smaragdite.
(2.) Epidote-Euphotide.—Similar to the preceding, but more tough, and
heavy. Specific gravity, 3.1-3.4. The base a compact whitish epidote (called
hitherto saussureite), according to T. S. Hunt. From the Alps.
(3.) Eclogite, or Garnet-Euphotide.—Either whitish, greenish, or reddish;
very tough and heavy. Specific gravity, 3.2-3.5. The eclogite of Europe con¬
tains grass-green smaragdite in a reddish garnet base. The related rock from
Canada, according to T. S. Hunt (Logan's Report for 1853-56, p. 450), contains
grayish cleavable hornblende or pyroxene in a whitish or yellowish base. Part
of the base is in some cases feldspathic: its low specific gravity—2.8—serves to
distinguish this variety.
4. Hydrous Magnesian Series.
86. The hydrous magnesian series, characterized by the presence
of the hydrous magnesian minerals talc, serpentine, or chlorite (§ 66),
ranges from a granite-like rock called protogine (containing the con¬
stituents of granite, excepting talc in place of mica) down to the
semicrystalline talcose and chloritic slates; and also to compact
flinty rocks near aphanite. Besides these, there are the serpentine
rocks. Talc and serpentine are silicates of magnesia and water
alone, while chlorite contains alumina and oxyd of iron. The
chloritic rocks consequently abound often in hornblende, and are
frequently associated with rocks of the hornblende series. The
KINDS OF ROCKS.
81
color of the rocks is some shade of dull grayish, brownish, olive, or
blackish green. Specific gravity, 2.4 to 3; or over 3 if containing
hornblende.
(1.) Protogine.—A granular crystalline or granite-like rock, con¬
sisting of quartz, feldspar, and talc, with sometimes some mica
(micaceous protogine). The feldspar may be orthoclase or oli-
goclase, or both (both in the Alps), and is sometimes in distinct
crystals (porphyry). Color, grayish white or greenish white.
Gneissoid protogine is a gneiss-like rock, consisting of quartz,
feldspar, and talc, between talcose schist and gneiss in its charac¬
ters. Occurs in the Alps.
(2.) Chloritic Gneiss.—A gneissoid rook consisting of quartz and feldspar,
and often mica, with soft olive-green granular chlorite distributed through it in
small patches.
(3.) Talcose Schist.—A slaty rock, less crystalline than mica
schist, and less evenly schistose, characterized by a slight greasy
feel, glistening and talcose look upon the surface of the slate, a
greenish-gray or grayish-green to brown color. Texture usually
near that of argillite, sometimes with quartz and feldspar in grains
like mica schist. It passes on one side into schistose talc, which is very
greasy to the feel, and is pure talc; and on the other into argillite,
or mica schist. Frequently contains actinolite, garnet, staurotide,
tourmaline, pyrites ; and the intersecting or intercalated quartz
often contains gold.
(4.) Steatite, or Soapstone (| 66).—A massive, more or less
schistose rock, fine-granular; color, gray to grayish-green ; feel,
very soapy; composition, that of fine talc. Often contains crys¬
tals of tourmaline (p. 58), dolomite, or brown spar (p. 63), or mag¬
netite (p. 65).
Rensselaerite is a kind of soapstone, of compact texture, and either gray,
whitish, greenish, brownish, or even black, color. For an analysis by T. S.
Hunt, see Logan's Rep. for 1853-56, p. 4S3. Occurs in the towns of Fowler,
De Kalb, Gouverneur, and others, St. Lawrence co., N.Y., and also in Gren-
ville, Canada.
(5.) Ciiloritic Schist.—A more or less slaty rock, like the pre¬
ceding, but of an olive-green or greenish-black color, though some¬
times pale greenish-gray ; it is somewhat less greasy to the feel,
usually less shining ; the chlorite fine-granular and soft; sometimes
in deep-green mica-like scales or plates. Often contains black and
dark-green hornblende in acicular and grouped crystals and fibrous
masses, also magnetite in octahedral crystals. Graduates into horn-
blendic slate. A rock of this kind from Potton, Canada, analyzed
7
82
LITHOLOGICAL GEOLOGY.
by T. S. Hunt, has the composition of ordinary chlorite. (Logan's
"Rep. for 1853-50.)
(6.) Serpentine ($ 66).—A massive uncleavable rock, of dark-green
to greenish-black color, easily scratched with a knife, and often a
little greasy to the feel when a surface is smoothed. Although
generally of a dark-green color, it is sometimes pale grayish and
yellowish green, and mottled.
A serpentine rock containing diallage is the gabbro of the Italians.
(7.) Schillerite, or Schiller rock, Diallage rock.—A dark-green to greenish-
black rock, made up of Schiller spar, and having the following composition :
1. Kohler; 2, T. S. Hunt (Logan's Rep., 1855-56, 443); 3, id. of the pure
diallage :— ,
SiO3. AW. FeO. MgO. CaO. NiO. MnO. IIO.
1 43.90 1.28 13.01* 26.86 0.54 12.43 Kohler.
2. Canada 41.80 6.80 11.05 26.13 7.00 trace 7.60 Hunt.
3. Canada 47.15 3.45 8.73 24.56 11.35 trace 5.82 Hunt.
It is often associated with serpentine, chlorite, and talc-schist.
(8.) Opiiiolite (or verd-antique marble).—A variegated mixture
of serpentine and either carbonate of lime (calcareous ophiolite), do¬
lomite (dolomitic ophiolite), or carbonate of magnesia or magnesite
(magnesitic ophiolite). Color, dark green, mottled with lighter green
or white.
It often contains chromic iron sparsely disseminated through it, forming
irregular, black, submetallic spots ; also some talc, asbestus, sahlite; and analysis
often detects nickel as well as chrome. T. S. Hunt has found both nickel and
chrome in the serpentines or ophiolites of the Green Mountain range, in those
of Roxbury, Vt., New Haven, Ct., Iloboken, N.J., Cornwall, England, Banff¬
shire, Scotland, Vosges, France. They occur also in the pyrosclerite and Wil-
liamsite of Chester co., Pa., and in the antigorite of Piedmont. Hunt found
no nickel in serpentine from Easton, Pa., Montville, N.J., Philipstown, N.Y.,
Modum, Norway, Newburyport, Mass., and none from the Azoic series of rocks.
5. Hydrous Aluminous rocks,
87. These rocks consist largely of agalmatolite or pyrophyllite, and have a
close resemblance to talcose and serpentine rocks in feel, hardness, and ap¬
pearance.
Parophite.—Essentially agalmatolite ($ 67) in composition. Its fine-grained
texture and somewhat soapy feel are its striking peculiarities. It occurs both
as a slate and rock. The name was first given by T. S. Hunt to a variety
occurring in northern Vermont, and alludes to a resemblance in aspect to ser¬
pentine. The dysyntribite of Shepard, found in northern New York (§ 67),
is a rock variety.
* With some oxyd of chrome.
KINDS OF ROCKS.
83
Pyrophyllite Rock or Schist.—Like the preceding in appearance and soapy-
feel, but having the composition of pyrophyllite (§ 67). The color is white and
gray, or greenish white. Occurs in North Carolina; one of the varieties from
the Deep River region is used for slate-pencils.
6. Quartzose rocks.
88. (1.) Quartzite, or Granular Quartz Rock.—A very hard, com¬
pact rock, consisting of quartz grains or sand, and usually either
white, gray, or grayish red in color. Sometimes contains dissemi¬
nated scales of feldspar, mica, or talc, and in that case is often
laminated or schistose. It is but a step removed from ordinary
sandstone, and owes its peculiarities only to a process of consolid¬
ation.
(2.) Siliceous Schist.—A schistose, flinty quartz rock, not distinctly gra¬
nular in texture.
(3.) Arkose.—A quartz rock, containing much crystallized orthoclase dis¬
seminated through it. Occurs in the Vosges.
(4.) Itacolumite.—A schistose quartz rock, consisting of quartz grains with
talc or mica. On account of the talc or mica in the lamination, the finer kind
is sometimes flexible, and is called flexible sandstone. Occurs often in gold-
regions associated with talcose slates.
(5.) Jasper Rock.—A flinty siliceous rock, of dull red, yellow, or green
color, or some other dark shade, breaking with a smooth surface like flint. It
consists of quartz, with more or less clay and oxyd of iron. The red contains
the oxyd of iron in an anhydrous state, the yellow in a hydrous : on burning
the latter it turns red.
A dull-green chert (or impure flinty siliceous rock) from Cap Rouge, Canada,
afforded T. S. Hunt (Logan's Report for 1853-56)—Silica, 77.50, alumina, 8.50,
protoxyd of iron, 2.70, lime, 0'.73, magnesia, 2.35, soda, 1.38, potash, 1.66, loss by
ignition, 4.40 = 99.22. Part of the silica^—nearly 21 per cent.—was in the con¬
dition of opal.
(6.) Buhrstone.—A cellular siliceous rock, flinty in texture. It is used
for millstones. Found mostly in connection with Tertiary rocks, and formed
apparently from the action of siliceous solutions on pre-existing fossili-
ferous beds.
7. Iron-Ore rocks.
89. Specular Iron-Ore (Hematite) and Magnetic Iron-Ore occur as
rocks of considerable thickness among the metamorphic rocks, espe¬
cially the hornblendic and chloritic kinds. There are schistose or
laminated as well as massive varieties. These iron-ore beds occur
extensively in northern New York, Canada, Michigan, and Mis¬
souri ; also in Sweden and elsewhere. Their alternation with chlo¬
ritic and other schists and gneissoid rocks shows that they are meta^
84
LITHOLOGICAL GEOLOGY.
morphic as well as the schists. Titanic iron-ore occurs in great beds
of like extent in Canada. (See $ 72.)
Franklinite, an iron-zinc ore, is also one of the metamorphic rocks in northern
New Jersey.
3. Calcareous Hocks.—Carbonates and Sulphates.
90. (1.) Massive Limestone.— Uncrystalline Limestone.—Most lime¬
stone has been formed from shells and corals ground up by the
action of the sea and afterwards consolidated. The colors are dull
gray, bluish, brownish, to black. The composition is usually the
same as that of calcite, carbonate of lime ($ 69), except that impu¬
rities, as clay or sand, are often present. In texture they vary
from an earthy-looking limestone to a very compact semi-crystal-
line one; and from this kind the passage is gradual also to the
true crystalline.
(2.) Magnesian or Dolomitic Limestone ($69 [24]).—Consists of
carbonate of lime and magnesia, but is not distinguishable in color
or texture from ordinary limestone. The amount of carbonate
of magnesia present varies from a few per cent, to that in dolo¬
mite. Much of the common limestone of the United States is
magnesian.
Analyses of magnesian limestones :—1. Lower magnesian (Calciferous epoch),
by D. D. Owen; 2, id. of Iowa, J. D. Whitney; 3, Galena limestone of Iowa,
Whitney; 4, Niagara limestone, by Beck; 5, Carboniferous limestone of Iowa,
Whitney.
1.
St. Croix.
•2.
New
Galena.
3.
Garna-
ville.
4.
Lock-
port.
5.
Mt. Plea¬
sant.
Carbonate of lime
... 48.24
52.47
52.01
75.65
57.15
Carbonate of magnesia.,
... 42.43
42.13
42.25
20.70
39.24
Carbonate of iron
1.78
0.93
Insoluble (sand)
... 2.74
2.75
4.43
2.25
2.18
Oxyd of iron and alumina 6.14
0.87*
0.38
Ox. iron 0.35
1.06
,.. 0.40
and loss 1.05
0.31f
99.95
100.00
100.00
100.00
99.94
In some limestones the fossils are magnesian limestone, while the rock is
common limestone. Thus, an Orthoceras in the Trenton limestone of Bytown,
Canada (which is not magnesian), afforded T. S. Hunt—Carbonate of lime, 56.00,
carbonate of magnesia, 37.80, carbonate of iron, 5.95 = 99.75. The pale-yellow
veins in the Italian black marble called " Egyptian marble" are dolomite, ac-
eording to T. S. Hunt, and a limestone at Dudswell, Canada, is similar.
(3.) Hydraulic Limestone.—An impure or earthy limestone, con-
* Alkalies and loss.
f Carbonate of soda and trace of potash.
KINDS OF ROCKS.
85
taining some clay, and affording a quicklime the cement made of
which will set under water. An analysis of a kind worked at Bon-
dout, N.Y., afforded Beck—Carbonic acid, 34.20, lime, 25.50, mag¬
nesia, 12.35, silica, 15.37, alumina, 9.13, sesquioxyd of iron, 2.25.
(4.) Oolite, or Oolitic Limestone.—A rock consisting of minute
concretionary spherules, and looking like the petrified roe of fish:
the name is from the Greek uov, egg. It is sometimes magnesian.
(5.) Chalk.—A white, earthy limestone, easily leaving a trace on
a board. Composition, the same as that of ordinary limestone.
(6.) Marl.—A clay containing a large proportion of carbonate
of lime,—sometimes 40 to 50 per cent. If the marl consists largely
of shells or fragments of shells, it is called shell-marl.
(7.) Shell Limestone.—Coral limestone.—A rock consisting of shells
or corals.
(8.) Birdseye Limestone.—A compact limestone having crystal¬
line points disseminated through it.
(9.) Travertine.—A massive but porous limestone, formed by deposition
from springs or streams holding carbonate of lime in solution in the state of
bicarbonate. The rock abounds on the river Anio, near Tivoli, and it is there
used as a building-material. St. Peter's, at Rome, is constructed of it. The
name is a corruption of Tiburtine.
(10.) Stalagmite, Stalactite.—Depositions from waters trickling through
the roofs of limestone caverns, form pendent calcareous cones and cylinders
from the roofs, which are called stalactite, and incrustations on the floors, which
are called stalagmite. The layers of successive deposition are usually distinct, and
make the material appear banded. They are rarely transparent, usually translu¬
cent to subtranslucent or opaque, and white, grayish, or faint yellowish in color.
2. Crystalline Limestone.
91. Granular Limestone ($ 69) (Statuary Marble).—Limestone
having a crystalline granular texture, white to gray color, often
clouded with other colors from impurities. The impurities are
often mica or talc, tremolite, white or gray pyroxene, or scapolite; some¬
times serpentine, through combination with which it passes into
ophiolite (§ 86), chondrodite, apatite, corundum.
Dolomite.—Not distinguishable by the eye from granular lime¬
stone (| 69).
3. Consisting of Sulphate of Lime.
92. Gypsum.—Sulphate of lime, as described in \ 70. The earthy
kinds often contain the crystallized mineral in spots or fissures;
and in many places it is associated with anhydrite, or sulphate
of lime containing no water (g 70 [27]). The borate of magnesia,
80.
LITHOLOGICAL GEOLOGY.
(Boracite), and Polyhalite, are often found in gypsum-beds; also,
rarely, hydrous borate of lime (Hayesine), as in Nova Scotia.
Gypsum is deposited from sea-water; but the gypseous rocks
appear generally to have been formed by the action of sulphuric
acid (from decomposition of sulpliurets or volcanic vapors) on
limestone or carbonate of lime. The action drives off the carbonic
acid and makes sulphate of lime, or gypsum.
4. Igneous Rocks.
93. Igneous rocks are those which have been ejected in a melted
state either from volcanoes or through fissures in the earth's crust .
As the crystallizing of superficial deposits may produce rocks like
those that are of true igneous origin, the same species in a few
cases occur in both divisions. Thus, there are metamorphic
diorite and porphyry, as well as igneous diorite and porphyry.
The igneous rocks differ from most of the metamorphic series in
the absence or very sparing occurrence of quartz.
There are two series of igneous rocks,—the feldspathic, having
light colors and being of low specific gravity, and the augiticT having
dark colors with high specific gravity.
1. Feldspathic series.—Consisting mainly of a feldspathic base, with,
often, disseminated crystals of some kind of feldsj^ar, or of horn¬
blende or pyroxene. Color, white, gray, bluish gray, grayish
brown. G. = 2.4-2.8. Occasionally, as in the porphyries, dark red
and brown. The light colors and low specific gravity are owing
to the absence or sparing dissemination of iron.
2. Augitic series.—Consisting of feldspar and hornblende or augite
(greenish-black or black pyroxene). Color, dark gray, dark gray¬
ish brown, dark greenish brown, greenish-black to black. G. = 2.9
-3.6. The high specific gravity and dark colors are owing to the
presence of iron as magnetic or titanic iron, or as a constituent
of the augite or hornblende.
1. Feldspathic Series.
94. (l.j Feldspathic Trap.—A rock consisting of crystallized feldspar, and
sometimes called, from its color, white trap. Varieties occurring in Canada
have a whitish, grayish, or pale yellowish color, also a pale fawn color. Com¬
position of a variety from Chainbly, Canada, according to T. S. Hunt (Logan's
Rep. for 1853-56), consisting of orthoclase, as follows :—
SiO3. A1203. Fe^O3. CaO. NaO. KO. Ignition.
1. Crystals. 66.15 19.75 0.95 5.19 7.53 0.55 = 100.12
2. Paste 67.60 18.30 1.40 0.45 5.85 5.10 0.25 = 98.95
KINDS OF ROCKS.
87
Certain dikes in the Montreal Mountain are of this kind, except that in
some the feldspar is a soda feldspar. Found also at Lachine. A similar
rock occurs in Australia in Prospect Hill, near Paramatta, New South Wales.
(2.) Porphyry.—A rock the mass or base of which is a compact uncleavable
feldspar, containing disseminated crystals of feldspar (orthoclase or oligoclase),
giving it an appearance, when polished, of being spotted with white or some
pale color, the spots rectangular or nearly so in form. Color, base grayish,
purplish,to deep red and brown; and crystals either large or minute. The feld¬
spar either orthoclase or oligoclase; mica or hornblende sometimes present.
Specific gravity of the red antique porphyry, 2.62-2.77.
This rock closely resembles true metamorphic porphyry, like that from the
vicinity of Boston. The antique green porphyry of Greece is diabase por¬
phyry (§ 85). G. = over 2.9.
Much of the so-called porphyry of the Andes and Mexico is a porphyry con¬
glomerate, in which both the pebbles and base are spotted with feldspar crys¬
tals, and the texture looks homogeneous until closely examined.
(3.) Phonolite (Clinkstone).—Compact, of grayish blue and other shades of
color, more or less schistose or slaty in structure; tough, and clinking under the
harqmer like metal when struck, whence the name. Often contains dissemi¬
nated crystals of glassy feldspar and hornblende, and sometimes mica. Con¬
sists of glassy feldspar (orthoclase or oligoclase), with nepheline or a zeolite
($ 68). Action of muriatic acid separates it into a soluble and an insoluble state,
the former including all the nepheline or zeolite. Analysis by Jenzsch of the
Bohemian phonolite,—Silica, 56.28, alumina, 20.58, lime, 0.46, soda, 9.07, potash,
5.84, lithia, 0.05, protoxyd of iron, 2.86, protoxyd of manganese, 1.45, magne¬
sia, 0.32, titanic acid, 1.44, phosphoric acid, 0.29, loss by ignition, 1.29, chlorine,
0.54, sulphur, 0.02; from which he deduces that it consists of 53.55 of glassy
feldspar, 31.76 of nepheline, with some hornblende and sphene (nepheline or
zeolite). Other phonolites consist of 18 to 50 per cent, of soluble silicate.
Common Phonolite.—Schistose, without distinct feldspar crystals, and contain¬
ing a zeolite disseminated through the mass, which is usually regarded as an
essential ingredient of the rock.
A peculiar feldspathic igneous rock occurring at Lachine, in Canada, having
a reddish, fawn-colored base, brittle, G. = 2.414, and H. = 5, consists, like pho¬
nolite, of feldspar (orthoclase) and a zeolite (probably natrolite) in nearly equal
parts. It forms dikes, and is in the same region with the dikes of white trap
mentioned in $ 94 (1).
Porphyritic Phonolite.—Containing disseminated glassy feldspar crystals.
PhonoliticLava.—Differing from trachyte in being more cellular and in not
having the peculiar roughness of trachyte over a surface of fracture.
(4.) Trachyte.—Color, pale grayish blue, rarely greenish, yellowish, red¬
dish ; texture peculiarly rough to the feel, and usually porous. Often contains
disseminated crystals of glassy feldspar and hornblende, and some little free
quartz, also mica. G. = 2.6-2.7. Decomposed by the action of muriatic acid
into a soluble and an insoluble silicate, the former in less proportion than in
clinkstone, or 10 to 14 per cent. Composition of the whole (from Drachenfels),
according to Abich,—Silica, 67.09, alumina, 15.64, potash, 3.47, soda, 5.08,
lime, 2.25, oxyds of iron, 4.59, magnesia, 0.98, protoxyd of manganese, 0.15,
88
LITHOLOGICAL GEOLOGY.
titanic acid, 0.38, water, etc., 0.45. In others, silica forms 61 to 67 per cent,
of the whole.
Tracliytic lava.—A very cellular trachyte.
Domite.—-An earthy friable trachyte, from Puy de Dome, Auvergne.
Slaty trachyte.—Structure schistose.
Porpliyritic trachyte.—Containing disseminated crystals of glassy feldspar,
often without any hornblende.
Granitoid trachyte.—A granular aggregate of glassy feldspar, hornblende, and
mica. Approaches dioritc.
Hornblcndie trachyte.—Containing much hornblende in disseminated crystals.
(5.) Pumice.—Very light, porous, with the pores minute, capillary, and
parallel. Color, pale grayish, greenish, yellowish, and sometimes of darker
shades. It is a kind of porous trachyte. Contains 69 to 70 per cent, of
silica, and probably, therefore, some free quartz. Composition, according to
Berthier,-—Silica, 70.0, alumina, 16.0, sesquioxyd of iron, 0.5, lime, 2.5, pot¬
ash, 6.5, water, 3.00 = 98.50. Abich obtained 6.21 percent, of soda, and 3.98
of potash.
Often contains glassy feldspar, and sometimes hornblende, mica, leucite.
(6.) Obsidian.—A volcanic glass, taking its characters from the composition
of the volcanic lavas. The lavas cooling slowly form stony lava, and cooling
rapidly a glassy,—the two being different conditions of the same substance.
Obsidian connected with feldspathic lavas is either solid or slag-like (scoria-
ceous), and in color brown to greenish-black and black. A Mexican variety
afforded Vauquelin—Silica, 78, alumina, 10, potash and soda, 6, lime, 1, sesqui¬
oxyd of iron, 2, id. of manganese, 1.6 = 98.6. Another, from Telki-Banya,
afforded Erdmann—Silica, 74.80, alumina, 12.40, potash and soda, 6.40, lime,
1.96, sesquioxyd of iron, 2.03, id. of manganese, 1.31, magnesia, 0.90 = 99.80.
Spherulitic obsidian.—Contains small feldspathic concretions.
(7.) Pitchstone (Retinite).—An imperfectly-glassy volcanic rock, pitch-like
in appearance, and of various colors from gray to black, through greenish,
reddish, and brownish shades. It contains 70 to 73 per cent, of silica, and, in
some of the published analyses, 8 to 10 per cent, of water. Delesse obtained
(Bull Soc. Geol. de France, 1853, p. 105) for a pitchstone from Santa Natolia—
Silica, 62.59. alumina, 16.59, protoxyd of iron, 3.17, id. of manganese, 0.55,
lime, 1.15, magnesia, 2.26, potash, 6.48, soda, 3.14, water and organic matter,
3.90 = 99.83.
(8.) Peari.stone.—Near pitchstone, but less glassy and more pearly in
lustre: usually grayish in color, also yellowish, brownish, and reddish. The
peculiar pearly appearance is due to an intimate mixture of a portion of the
rock in the glassy state with another larger portion in the stony state. It
often contains spherical concretions, called spherulites, which consist of feldspar
with an excess of quartz. The silica varies from 68 to 80 per cent. An analysis
by Erdmann of a variety from Hlinick afforded—Silica, 72.87, alumina, 12.05, soda
and potash, 6.13, lime, 1.30, magnesia, 1.10, sesquioxyd of iron, 1.75, water, 3.00
= 98.20.
(9.) Melaphyr.—Closely related in its connections to dolerite and basalt, hut
consisting of compact labradorite, and having a specific gravity not above 2.7.
Color, reddish gray, greenish blackish, and sometimes mottled. Different rocks
KINDS OF ROCKS.
89
have been included under this name. Some that have been called trap are
here included.
2. Augitic or Basaltic Series.
95. (1.) Diorite.—Similar to the metamorphic diorite, but usually the horn¬
blende less abundant and the feldspar less finely developed. Color, grayish
white. A variety consisting of hornblende and anorthite constitutes some of
the dikes of Canada. (T. S. Hunt.)
(2.) Dolerite {Trap, in part).—Texture crystalline-granular to cryptocrys-
talline (the fine variety often called anamesite). Color, dark gray, greenish and
brownish black. Consists of labradorite and augite, with often magnetic iron.
Sometimes columnar. G. = 2.75-3.
Porphyritic dolerite.—Speckled with crystals of feldspar, or with feldspar and
augite, or with augite alone.
Amygdaloidal dolerite.—Containing nodules of zeolites, chlorite, quartz, or
calcite. Includes much of the so-called amygdaloid.
Another variety contains the augite in black crystals.
Boleritic lava.—Structure scoriaceous or very cellular.
(3.) Basalt.—Like dolerite, but less granular than the coarser dolerite, and
containing also chrysolite in grains looking like green glass. Compact. Often
columnar. G. = 2.9-3.2.
Porphyritic basalt.—Speckled with crystals of feldspar.
Amygdaloidal basalt.—Containing amygdals of zeolites, etc. ($ 68).
Basaltic lava.—Scoriaceous or very cellular. The lava may be porphyritic
with feldspar or augite crystals.
(4.) Leucitophyr.—A dark-grayish, fine-grained, cellular volcanic rock, con¬
sisting of augite and leucite with some disseminated magnetic iron. It is the
lava of Vesuvius. The leucite is either in whitish grains or in trapezohedral
crystals (see § 57), and is disseminated like the feldspar crystals in a
porphyry.
(5.) Nephelinite (Nephelin-dolerite).—A crystalline, granular volcanic rock,
consisting of nepheline and augite, with some magnetic iron, the nepheline
partly in distinct crystals. Color of the coarser kind, grayish or whitish;
of the finer, dull ash-gray.
The tufas and conglomerates of volcanic regions are noticed on p. 74.
Wacke is an earthy rock made of basaltic earth partially compacted,—a kind
of tufa.
(6.) Basaltic Obsidian.—The massive obsidian of Kilauea, Hawaii, a region
of basaltic lavas, contains 22 per cent, of protoxyd of iron, and the capillary
(Pole's hair) 30 per cent. The light scoria of the crater is an impure volcanic
glass, very much inflated.
90
LITHOLOGICAL GEOLOGY.
II. CONDITION, STRUCTURE, AND ARRANGEMENT
OF ROCK-MASSES.
96. The rock-masses of the globe, or terrains, as they are called,
occur under three conditions: (1) the stratified, (2) the unstratified,
and (3) the vein condition. Under each there are peculiarities of
structure and of arrangement.
I. STRATIFIED CONDITION.
Under this head the subjects for consideration are:—1. The na¬
ture of stratification; 2. The structure of layers; 3. The positions
of strata,—both their natural positions and dislocations; 4. The
general arrangement of strata, or their chronological order.
1. Nature of Stratification.
97. Stratified rocks are those which are made up of a series
of layers or strata. The annexed sketch represents a section
of the strata as exhibited along
Genesee River, at the falls near
Rochester. The whole height of
the section is 400 feet. At bottom
there is a thick stratum of sand¬
stone (1); next above it lies a hard,
gray layer (2), which has been
called the Gray Band. Upon this
rests (3) a thick bed of greenish shale, a fragile, imperfectly
slaty rock. Next (4) is a compact limestone forming a wide¬
spread stratum resting on the shale. Above this (5) is another
greenish shale, much like that below. Then (6) is another great
stratum of limestone; then (7) another thick bed of shale; and,
finally (8), at the top is a limestone wholly different from those
below. The transition from one stratum to another is quite
abrupt, and, moreover, each may be traced for a great distance
through the adjoining country.
Throughout far the larger part of America and all the other con¬
tinents the rocks lie similarly in layers, so that stratified rocks are
of almost universal distribution. They make up the most of the
Appalachians ; cover nearly all of New York ; underlie the great
plains of the Ohio and Mississippi; occur over the larger part of
the slopes and summit of the Rocky Mountains; along much of the
Pacific border, as well as the Atlantic; and exist as red sandstone
Fig. 60.
STRATIFICATION*
91
in the Connecticut valley. They are the prevailing rocks of Bri¬
tain, including within their series the chalk, oolite, coal strata, and
others. They occur over nearly all Europe, spread throughout the
great plains of Russia, through Asia nearly to the top of the Hima¬
layas, South America in many places to the summit of the Andes,
and through Africa and Australia. These stratified rocks are in strik¬
ing contrast with the unstratified,—granite, for example, which may
show no appearance of layers even through heights of a thousand
feet or more. Many volcanic masses of rock are unstratified. Yet
the volcanic mountain has usually a stratified arrangement , successive
layers of lava and volcanic sand or earth being piled up to make
the cone. Even among crystalline rocks the distinction of strata
may often be made out, although much disguised by changes in
the course of their history.
The succession of strata in stratified rocks is exceedingly various.
In the section given, there are alternations of limestones, shales,
and sandstone. In others, as at Trenton Falls, N.Y., there are
only limestones in sight; but were the rocks in view to a much
greater depth, sandstone strata would be seen. In still other
regions, there are alternations of conglomerates and shales ; or
conglomerates with shales and coal-beds; or conglomerates with
limestones and sandstones ; or shales and sandstones alone.
The thickness of each stratum also varies much, being but a few
feet in some cases, and hundreds of feet in others ; and the same
stratum may change in a few miles from 100 feet to 10, or disap¬
pear altogether. In the Coal formation of Nova Scotia there are
14,000 feet of stratified beds, consisting of a series of strata mainly
of sandstones, shales, and conglomerates, with some beds of coal;
and in the Coal formation of Pennsylvania there are 0000 to 7000
feet of similar character.
98. After these illustrations, the following definitions will be
understood.
a. Stratification.—A succession of rock-layers, either of the same
or of different kinds.
b. A layer.—A single member or bed in a stratified rock. It may
be thick or thin, and loosely or strongly attached to the adjoining
layers. In the section, fig. GO, the limestones 4 and G consist of a
great number of layers; and in all limestone regions many are
piled together to make the great mass of limestone.
c. A stratum.—The collection of layers of one kind which form a
rock as it lies between beds of other kinds. In the section re¬
ferred to (fig. 60), the limestones 4, G, and the shale masses 3, 5, 7,
are each a stratum. A stratum may consist of many layers.
92
L1THOLOGICAL GEOLOGY.
d. A formation.—A series of strata comprising those that belong to
a single geological aye or a single period, or subdivision of an age,
and which, consequently, have a general similarity in their fossils
or organic remains. The Coal formation includes many strata of sand¬
stone, shales, limestones, and conglomerates.
AVhile this is always the general idea connected with the term formation, the
use of it is not uniform. Geologists speak of the Silurian formation, Devonian
formation, Carboniferous (or Coal) formation, etc., making each cover a geo¬
logical aye. But they often apply the term also to subordinate parts of these
formations. Thus, under Silurian we have the Upper Silurian formation and
the Lower Silurian formation; and under each of these there are subordinate
formations, as the Trenton formation, including several strata of the Trenton
period in the Lower Silurian ; the Niagara formation for the lower part of the
Upper Silurian. These subdivisions embrace generally many strata, and have
striking peculiarities in their organic remains; and hence this use of the word
formation.
e. A seam is a thin layer intercalated among the layers of a rock,
and differing from them in composition. Thus, there are seams of
coal, of quartz, of iron-ore. Seams become beds, or are so called,
when they are of considerable thickness ; as, for example, coal-beds.
99. These strata, which constitute so large an extent of the
earth's crust, have been formed mainly by the action of water. As
the ocean now makes accumulations of pebbles, sand, and muddy
flats along its borders, and muddy bottoms for scores of miles in
width along various sea-shores, so it formed by the same means
many of the strata of sand and clay which now constitute the
earth's rocks ; and in this work the sea often had the advantage,
in early times, of sweeping widely over the just-emerging continent.
Again, as the rivers bring down sand and mud and spread them in
vast alluvial flats, making deltas about their mouths thousands
of square miles in area, so in ancient time beds of sand and clay
were accumulated by these very means and afterwards consolidated
into rocks. Again, as shells and corals, by growdng in the ocean
where shallow, under the action of the waves, produce the accumu¬
lating and rising coral-reef some hundreds of miles long in the pre¬
sent age, so in former ages shells and corals grew and multiplied and
made coral-reefs and shell-rocks, and these old reefs are the lime¬
stone strata of the world. The agency of water and life in these great
results is particularly considered under Dynamical Geology.
2. Structure of Layers.
The structure of layers is due either to the original deposition
of the material, or to subsequent changes.
100. (1.) Kinds of structure and markings originating in the
STRATIFICATION.
93
act or mode of deposition.—The kinds of structure are, illustrated
in the annexed figure, and are as follow:—a, the massive; b, the
slialy; c, the laminated; d and e, the compound or irregularly bedded.
Fig. 61.
These terms, excepting the last, have been already explained ($ 80).
The massive is especially characteristic of pure sandstones and con¬
glomerates. But if sandstones are argillaceous, that is, contain
some clay, they are laminated, or break readily into slabs, like
ordinary flagging-stones ; and the thinness of the flags increases
with the amount of clay. A clayey rock is usually shady or an im¬
perfect slate.
The compound structure is of three kinds,—the beach structure, the
ebb-and-flow structure, and the sand-drift structure.
In the beach structure, as exemplified in d, the subordinate layers
are very irregular in thickness and extent, often thinning out at
short intervals and varying from pebbles or stones to sand and
clay. This structure is observed in any sea-beach where a cut has
exposed its interior arrangement.
In the ebb-and-flow structure (e), the bed, although it be but
a few feet thick, consists of layers of various kinds, some of which
are horizontally laminated, and others obliquely so with great
regularity, as in the figure. The succession of members indicates
frequent changes or reversals in the currents during the deposi¬
tion. Such changes attend the ebb and flow of the tides or tidal
currents or waves over a shallow bottom.
In the sand-drift structure (/), the layers consist of subordinate
parts of very various lamination, one dipping in one direction and
another in another, as if a laminated hillock made by sand drifted
by the winds on a coast (for such sand-drifts are always in layers)
had been partly carried away, and then other layers been thrown
94
LITHOLOGICAL GEOLOGY.
over it by the drifting winds at a new inclination, and this
violent removal and replacement often and variously repeated.
Fig. 61/, representing this mode of structure, is from Foster &
Whitney's Report on the Sandstone Rocks of Lake Superior.
Fig. 61 e is also from the same work.
101. Besides these kinds of structure, there are markings in the
strata which are of related origin,—viz.: ripple-marks, wave-marks,
rill-marks, mud-cracks, and rain-drop impressions.
Fig. 62. Fig. 63.
(1.) Hippie-marks (fig. 62).—A series of wavy ridgelets, like the
ripples on a sand-beach.
(2.) Wave-marks.—Faint outlinings, of curved form, on a sand¬
stone layer, like the outline left by a wave along the limit where
it dies out upon a beach.
(3.) Rill-marks (fig. 63).—Little furrows made by the rills that flow
down a beach after the retreating wave or tide, and which become
apparent especially where a pebble or shell lies, the rising of the
water upon the pebble causing a little plunge over it and a slight
gullying of the surface for a short distance.
(4.) Mud-cracks (figs. 64 and 65).—Cracks intersecting very irregu¬
larly the surface or a portion of a layer, and formed by the drying
of the material of the rock when it was in the state of mud, just
as a mud-flat left exposed to the drying sun now cracks. The
original cracks are usually filled with a material harder than the
rock, so that when it becomes worn the surface has a honeycomb
appearance, from the prominence of the intersecting ridgelets, as
in fig. 65. Moreover, these ridges are generally double, the filling
STRATIFICATION.
95
having been solidified against either wall of the crack until the
two sides met at the centre and became more or less perfectly
Fig. 64. Fig. 65.
united. Specimens of rock thus honeycombed are sometimes
called septaria (from septum, partition); but the term is little used
in science.
Fig. 66.
(5.) Rain-prints (fig. G6).—Rounded pits or depressions, made by
drops of rain on a surface of clay or half-dry mud. On a reversed
layer the impressions appear raised instead of depressed, being
casts made in the pits which the rain had formed.
(6.) There are also markings which are attributed to the
flowing of thick mud. There are others, produced apparently by
small eddyings of water in clay or mud which work out concavities
that afterwards become filled with clay and look as if made by
the valves of shells.
102. (2.) Kinds of structure not properly a result of deposition,
and mostly of subsequent origin.—The kinds of structure here
96
LITHOLOGICAL GEOLOGY.
included are (a) the concretionary, (b) the jointed, and (c) the slaty.
They are produced either in the process of consolidation or during
subsequent changes.
103. a. The Concretionary Structure.—'This kind of structure has
been briefly explained in \ 80, and is here further illustrated.
Fig. 07 is a sphere,—a very common form. The sphericity is
frequently as perfect as in a bullet or cannon-ball, though usually
more or less ovoidal, and sometimes quite distorted. The size varies
Figs. 67-79.
from a mustard-seed and less to a foot or more ; and generally those
that are together in a layer of rock approach a uniformity in size.
They often have a shell, or a fragment of a plant, or some other
object, at the centre. In other cases they are hollow and filled
with crystals. The structure is often in concentric layers.
Figs. 68 to 75 are views of sections showing the interior. In 68 there is a
fossil shell as a nucleus; in some cases a fossil fish forms the interior of a con¬
cretion.
The structure in fig. 68 is represented as solid without concentric layers. In
fig. 69 the structure is concentric, the layers either firmly adherent or easily
separating. In 70 a variety with a radiated structure is shown, consisting of
crystalline fibres diverging from the centre and showing crystalline apices over
the exterior surface. In fig. 71 the exterior is concentric but the interior is
filled with radiated crystallizations.
CONCRETIONARY STRUCTURE.
97
In fig. 72 the interior is irregularly cavernous, as if it had cracked thus in
drying. In fig. 73 there is a similar result, but with more numerous and smaller
cracks, making a reticulation of them; and when these cracks are subse¬
quently filled by carbonate of lime, heavy spar, or other material, by a process
of infiltration, it becomes a kind of septnrium, and forms frequently a beautiful
object when polished. Some flattened concretions of this kind are a yard in
diameter. In 74 the interior is irregularly hollow, and filled around with a layer
of crystals (quartz crystals are the most common in such a condition), forming
what is called a cjeode,—a little crystal grotto. In fig. 75 the concretion is
hollow and contains another small concretion. This variety is not uncommon.
They rattle in the hand when shaken.
Fig. 76 a, b are different views of flattened or disk-shaped concretions;
77 is another, approaching a ring-shape; 78, a combination of three flattened
concretions; 79, another, which is remarkable for the symmetry of its compound
form while so irregular.
Fig. 80. Fig. 81.
Fig. 80 is part of a clay layer made up of flattened concretions. A concre¬
tionary layer often graduates insensibty into one in which no concretions are
apparent, through the coalescence of the whole. Fig. SI represents a rock
made up of concretions of the size of peas,—a calcareous rock called pinolite
(from pisum, a pea). Each concretion has a concentric structure, the layers
easily peeling off. The oolite (named from wov, egg) is similar, except that
the concretions are as small as the roe of fish, or even as fine as grains
of sand.
Fig. 82.
104. Fig. 82 exhibits a crystalline rock with spherical concretions imbedded
in its mass and not separable from it,—each layer (of the three represented
8
98
LITHOLOGICAL GEOLOGY.
in each concretion) consisting of different minerals: for example, garnets
characterizing the centre, feldspar the middle layer, and mica the outer; and all
making a solid mass. The constitution of such concretions is very various. In
rocks containing feldspar they usually consist largely of feldspar, and some¬
times of feldspar alone, or of feldspar with some quartz. The concretions in
pitchstone and pearlstone (called sjikerulites) are almost purely feldspathic, and
often separate easily from the rock.
105. Fig. 83 represents basaltic columns, like those of the Giants' Causeway,
having the tops concave: at each joint in the columns, in such a case, there
would be the same concavity, a convex and concave surface fitting neatly
together like a ball-and-socket joint. This tendency to break with concave or
convex surfaces is another example of concretionary structure; and in the
example referred to, each column is an independent line of concretionary
solidification distinct from the others. This concretionary structure is often
wholly unobservable in the solid unaltered rock. But let it begin to decompose
by atmospheric agencies, and concentric or successive concave layers become
apparent; and sometimes they are so perfectly developed as to separate easily
and afford thin plates, or an imperfectly slaty structure.
106. In some granite and sandstone, decomposition develops in like manner
a concretionary structure. The rock, after partial alteration, peels off in con¬
centric layers, and a bluff of granite which has undergone the change some¬
times appears as if made up of huge rounded boulders piled together, with earth
or crumbling rock between; in fact, each of the masses resembling boulders was
the centre of a concretion. A sandstone often looks like an excellent stone for
buildings, which, .after an exposure of a few months, will fall entirely to pieces.
Complete immersion in water is often a protection to such stone; and they
may frequently be used architecturally for submarine purposes when not fit for
structures out of water.
Fig. 84 is a case of concretion in a sandstone alongside of a small fissure,
observed in Australia. The two concretions measured twenty feet across.
They consisted of layers from half an inch to two inches thick, which separated
rather easily. The rock elsewhere was without concretions.
Fig. 85 is from an argillaceous sandstone which before consolidation had been
intersected by slender mud-cracks, and subsequently, on hardening, each areo-
let became a separate concretion. The action of the sea had worn the surface
and brought the structure out to view.
Fig. 84.
CONCRETIONARY STRUCTURE.
99
107. The concretions in sandstones are usually spheres or sphe¬
roidal, while those in argillaceous layers are flattened disks.
Fig. 85.
In fig. 86 the lower sandstone layer (1) has no concretions; the other (3) con¬
tains spherical concretions; in the upper layer (4), an argillaceous sandstone, the
concretions are somewhat flattened and coaleseent; in the shaly layer (2) they
are very much flattened, and in its lower part coa¬
leseent.
Concretions sometimes take fanciful or imitative
shapes; and every geologist has had petrified tur¬
tles, human bones, skulls, and toads brought him,
which were only examples of the imitative freaks
of the concretionary process. The turtles are usually
what are mentioned as septaria on page 95. Occa¬
sionally concretions take long cylindrical forms, from
consolidation around a hole bored by a worm or mollusk, the hole giving pass¬
age to the concreting ingredient: or they derive their form from some rootlet
or stem of a plant, in which case they are often branched.
A radiated arrangement is common when no distinct concretions are formed,
as with quartz crystals in irregular cavities.
Sometimes ditferent points become centres of radia¬
tion, producing a blending of distinct radiations, as
in fig. 87.
Very many of the mineral species shoot into stellar
and globular radiated crystallizations. Others, like
pyrites, readily collect in balls or nodules around a
foreign body as a nucleus, or, if none is at hand,
around the first molecule of pyrites that commences
the crystallization. This tendency in nature to concentric solidification is so
strong that no foreign nucleus is needed. The iron-ore of coal-regions is
mostly in concretions in certain layers of the Coal measures. The rounded
masses often lie imbedded in the clayey layer, or are so numerous as to coalesce
into a solid bed.
108. b. The Jointed Structure.—Joints in rocks are planes of fracture
or division cutting directly across the stratification and extending
Fig. 86.
Fig. 87.
100
LITHOLOGICAL GEOLOGY.
through great depths. The planes of division are often as even as
if a thin blade had been drawn through with a clean long stroke.
These joints may be in one, two, or more directions in the same
rock, and they olten extend, with nearly uniform directions, through
regions that are hundreds of miles in length or breadth. The ac-
Fig. 88.
companying sketch represents the falling cliffs of Cayuga Lake,
and the fortress-shapes and buttresses arising from the natural
joints intersecting the rocks. The wear of the waters from time
to time tumbles down an old surface and exposes a new range
of structures.
Traversing the surface of a region thus intersected, the joints
appear as mere fractures, and are remarkable mainly for their great
extent, number, and uniformity. In case of two systems of joints—
the case most common—the rock breaks into blocks which are rect¬
angular or rhomboidal according as the joints cross at right angles or
not. In some places a layer looks like a rectangular pavement on
a vast scale. In others, where the layers are thick and coarse and
somewhat displaced, there is a resemblance to artificial fortifica¬
tions, or cities in ruins, which is quite striking. The main system
of joints is usually parallel to the strike of the uplifts, or else to
the range of elevations or mountains in the vicinity, or to some
general mountain-range of the continent; and the directions are
studied with much interest, because of their bearing upon the
geological history of the country.
The joints in rocks, when not too numerous, are often a great
assistance to quarrymen in quarrying rock, as they afford natural
sections of the layers.
109. c. Cleavage, or the Slaty Structure.—The slaty structure—or
cleavage, as it is called—is in some cases parallel with the planes of
deposition or bedding of a rock; and such examples of it come under
a former head. But in many of the great slate regions, as in that of
Wales, the slate-lamination is transverse to the bedding, as shown in
SLATY STRUCTURE.
101
fig. 89, in which the lines a, b, c, d show the lines of bedding, and
the oblique lines the direction of the slates. Whole mountains
have sometimes this kind of oblique or transverse lamination.
The sketch, fig. 89, by Mather,
is from the slate region of Colum- 89'
bia county, N.Y.
Occasionally the lines of deposition are
indicated by a slight flexure in the slates
at the spot, as in fig. 90. In other cases
there is a thin intermediate layer of quartz
rock or limestone which does not partake
of the cleavage. Fig. 91 represents an interstratification of clay-layers with
limestone, in which the former have the cleavage, but not the latter,—though the
limestone sometimes shows a tendency to it when argillaceous. Fig. 92 repre-
Fiv. 91.
Fig. 90.
sents a rock with two cleavage-directions; and 93 a quartzose sandstone which
has irregular cleavage-lines. These last two cases show that the jointed structure
is but one variety of the cleavage-structure, and that both have the same origin.
Sedgwick first detected the true lines of bedding, and ascertained that the
slaty structure was one that had been superinduced upon the clayey strata by
some process carried on since they were first deposited.
The foliated structure (or foliation) of mica schist, gneiss, and related schist¬
ose rocks appears to be sometimes transverse to the bedding, like most slaty
cleavage. Cut, as in the slates, it is not universally so, and the rock in each
region requires a special examination with reference to this point.
3. Positions of Strata.
110. The natural positions of strata as formed, and the positions
resulting from the disturbance or dislocations of strata, are two dis¬
tinct topics for consideration in this place.
102
LITHOLOGICAL GEOLOGY.
1. The natural positions of strata as formed.—Strata in their
natural positions are commonly horizontal, or very nearly so. The
level plains of alluvium and the extensive delta and estuary flats
show the tendency in water to make its depositions in nearly hori¬
zontal planes. The deposits formed over soundings along sea-coasts
are other results of sea-action ; and here the beds vary but little
from horizontality. Off the coast of New Jersey, for eighty miles
out to sea, the slope of the bottom averages only 1 foot in 700,—
which no eye could distinguish from a perfect level. As the processes
of the present period along coasts illustrate the grand method of
rock-accumulation in past time, it is plain that strata when in
their natural positions are very nearly, if not quite, horizontal.
Over a considerable part of New York and the States west and
southwest, and in many other regions of the globe, the strata are
actually nearly horizontal at the present time. In the Coal form¬
ation, the strata of which have a thickness, as has been stated, of
five to fifteen thousand feet, there is direct proof that the beds were
horizontal when formed; for in many of the layers there are fossil
trees or stumps standing in the position of growth, and sometimes
several of these rising from the same layer.
Fig. 94 represents these tilted coal-beds r, <\
with the stumps s, s, s. Since these trees
must have grown in a vertical position, or
at right angles to the ground, like all others,
and as now they are actually at right angles
to the layers, and parallel to one another,
they prove, whatever the present condition
of those layers, that originally they were horizontal. The posi¬
tion of shell-accumulations and coral-reefs in modern seas shows,
further, that all limestone strata must have been very exactly hori¬
zontal when they were in the process of formation.
Fig. 95.
tality may be produced by the slope of the sea-bottom in certain
cases; and off* the mouths of rivers in lakes (fig. 95) quite a con¬
siderable inclination may result from the fact that the successive
layers derived from the inflowing waters would take the slope of
the bottom on which they fall. Cases of inclined position from
Fig. 94.
STRATIFICATION.
108
this cause are necessarily of limited extent, since the conditions
required for the result are not such as are likely to exist on a very
large scale.
It follows, from these facts, that, unless strata have been disturbed
from their natural positions, the order in which they lie is the order of
relative age,—the most recent being highest in the series.
111. (2.) Dislocations of strata.—Strata, although generally in
horizontal positions when formed, are in most regions, at the present
time, tilted, or inclined, and the inclinations vary from a small angle
to verticality, or even beyond verticality. They have been raised
into folds, each fold often many miles in sweep and equal to a
mountain-ridge in extent. They have been crumpled up into
groups of irregular flexures, one fold or flexure succeeding to
another, till like a series of wrinkles—and necessarily coarse
wrinkles—on the earth's surface. Every mountain-region presents
examples of these flexures, or uplifts; and most intermediate plains
have at least some undulations in conformity with the system in the
mountains.
In connection with all this uplifting, there have been frac¬
tures on a grand scale; and strata thus broken have been dis¬
placed or dislocated by a sliding of one side of such a fracture
on the other, through varying distances from a few feet to
miles,—one side dropped down to this extent, or the other side
shoved up.
The subject, then, of the dislocations of strata is an important
one in Geology. The history of the continents and their mountain-
ranges, as well as of all their strata, is involved in it.
112. Uplifts, Folds, Dislocations. — The following sections illus¬
trate the general facts respecting these uplifts, folds, and dis¬
locations.
Fig. 96. Fig. 97.
Fig. 96 represents a part of the Coal formation broken and dislo¬
cated, the beds (the coal-beds 1 and 2 and the other layers) being
changed in direction as well as disjoined in the fracturing. Fig. 97
is another example of similar kind and greater extent, c is the
104
LITHOLOGICAL GEOLOGY.
coal-bed. It is broken by the line t t, which is here a wide fissure
filled by rock, ancl also by r r, another fissure filled by earth from
above. Fig. 98 is an actual section of a part of the Appalachians,
Fig. 98.
v^W7/'-
7k~
viV IV
in n
hi
iv
v vi \ vi yiv in h
six miles in length, showing the foldings and contortions of the
strata in those mountains.
Some of the kinds of flexures and curvatures are shown in the
Fig. 99.
a
^ " xf ak ^
X
e
annexed figures a-e, to appreciate which it must be understood
that these flexures may be each from a few feet to scores of miles
in extent, that they form undulations over vast regions, and some¬
times make lofty mountains.
The two slopes of a fold may be alike; or, as in b, c, d, one
may be much steeper than the other. The line a x shows the
position of the axial plane of the fold in each case. The
ridge-line of a fold may be horizontal, but more commonly it is
inclined and reaches gradually its greatest elevation. Moreover,
one fold or flexure in the rocks may succeed to another, or they
may form interrupted series. Such are some of the various con-
Fig. 100.
ditions which have been observed, especially in mountainous re¬
gions. Fig. 100 represents a section, by Logan, from the Azoic
DISLOCATIONS OF STRATA.
105
rocks of Canada. The folded rocks are often overlaid by others of
more recent date.
113. In describing the positions of strata, the following terms
are used:—
a. Outcrop.—A ledge or mass of rock coming to the surface, or
cropping out to view at the surface or above it (fig. 101).
Fig. 101.
b. Dip.—The slope of the strata, or the angle which the layers
make with the plane of the horizon; as ap (fig. 101). The direction
of the dip is the point of the compass towards which the strata
slope: for example, the clip may be 25° to the southeast, or 15° to the
west, and so on.
c. Strike.—-The direction at right angles with the dip, or the
course of a horizontal line on the surface of the inclined beds,
as s t.
The outcropping edges are sometimes called basset edges.
d. Anticlinal.—An anticlinal ridge is a ridge made of strata sloping
in opposite directions, as a, b, c, in fig. 99. An anticlinal axis is
the axial or ridge line of such a ridge ; it lies in the axial plane a x.
The word anticlinal is from the Greek avn, opposite, and k'/uvu, I
incline.
Fig. 102.
e. Synclinal.—A synclinal valley is a valley formed by strata sloping
downward from either side, as the middle part of fig. 99 b ; and a
10G
LITHOLOGICAL GEOLOGY.
synclinal axis is the axial line of the valley, in the plane ax. The
word is from aw, together, and kXlvu, I incline.
114. The direction of the strike is ascertained by means of a pocket-
compass, and the dip with an instrument called a clinometer. Two
instruments of this kind are represented in fig. 102. abcdis simply a
square block of wood, with a graduated arc c b, the centre of the arc
being at a point near a. From a pivot at this point a plummet or
pendulum is hung. On placing the side c d on an inclined plane
(A B) the angle is marked off by the position of the pendulum,
which of course hangs vertically.
A clinometer of this kind is often combined with a pocket-compass, the pen¬
dulum being hung from its centre. This is the most convenient kind of cli¬
nometer. If there is a black line marking horizontality across the face of a
clinometer of this kind, the angle may be taken by holding the instrument
between the eye and the dipping edges that are to be measured, and putting
this black line parallel with these edges; the pendulum will mark the angle of
dip. In the same manner the slope of the outline of a distant hill or mountain
may be measured.
The other clinometer has the form of a foot-rule jointed at the middle.
There is a level at 7t, by which the leg d e is brought to a horizontal line while
the other lies on the inclined plane. The angle between them is read off on a
graduated arc near the joint. At i a small compass is attached.
In using any clinometer, it is well to place a long strip of board upon the
layer of rock, lest the unevenness of surface lead to error.
Faults.—Faults are dislocations of the strata in the plane of a frac¬
ture, as seen in the coal-layers, figs. 90, 97 ; and the amount of fault
is the amount of dislocation. We may say, for example, a fault of
ten feet, or one thousand feet, or of five miles, and so on, according
to the extent of it as ascertained by actual measurement.
115. Complexities in stratified deposits arising from denudation and other
agencies.—By the denuding action of waters, strata are removed over
Fig. 103.
Fig. 104.
extensive territories, the tops or sides of folds are carried away, and
various kinds of sections made of the stratified beds, which are often
perplexing to the student.
DISLOCATIONS OF STRATA.
107
One of the simplest of these effects is the entire removal of the
rocks over wide intervals, so that the continuation of a stratum is
met with many miles distant, as in figs. 103, 104.
The result is more troublesome among the flexed or folded strata.
A series of close flexures, like fig. 105, worn off at top down to the
line a b, loses all appearance of folds, and seems like a series of layers
dipping in a common direction. This is best seen from a single fold
(fig. 106 a). If the part above the line a b were absent, the five layers
would seem to be a single regular series, with 1 as the top layer, 3,3'
the middle, and 1/ the bottom one ; while the fact is that 1 and V are
the same layer, and 3,3/ is actually a double one. In a number of
such folds the same layer which is made two in one fold would be
doubled in every other, so that in a dozen folds there would seem to
be twenty-four when in fact but one. A mistake as to the order of
succession would therefore be likely to be made, also as to the num¬
ber of distinct layers of a kind, and also as to the actual thickness
of the middle layer. Instances of a coal-layer doubled upon itself,
like 3,3', and of others made to appear like many distinct layers,
occur in Pennsylvania. On this point special facts are mentioned in
the section on the Coal formation.
Other effects of denudation are exemplified in the sketch fig. 9S. The
stratum No. III. is a folded one, with its top partly removed; the layers within
a short distance dip in opposite directions. The layer No. IV. to the left is
the same with IV. to the right; but they are widely disjoined and very different
in direction. Again, V. lies upon the top of the highest summit, nearly hori¬
zontally, and in a shallow basin: yet it is part of the stratum V. to the left,
which is obviously much folded. The observer finds it ne'eessary to study the
alternations of the beds with great care, in order to succeed in throwing into
system all the facts in such a region. The coal-regions of Pennsylvania, the
whole Appalachians, all New England, and much of Great Britain and Europe,
illustrate these complexities arising from flexures and denudation.
116. There is difficulty also in ascertaining the true dip of strata
from exposed sections. In fig. 107, stur is the upper layer of an
outcropping ledge of rock, dp the line of dip, s t the strike. The
ledge shows four sections 1, 2, 3, 4. On 1 the edges have the same
Fig. 105.
Fig. 106 a. Fig. 106 b.
LIT 110LOGICAL GEOLOGY.
dip as (I p. but 011 2, .">, and 4 the angle as obtained from the ex¬
posed edges would be different; and on the last the edges would
he horizontal, or nearly so. Thus all sections except the one in the
direction of the true line of dip (or at right angles to the strike)
would give a false dip. By finding the surface of a layer exposed to
Pig. 107.
view, the true direction of the dip or slope may be ascertained and
the error avoided.
117. The following figures (fig. 108) still further illustrate this subject, by
showing the variations of direction that may be obtained from the sections of a
single folded ridge, For simplicity of explanation, the fold is supposed to be a
symmetrical one, though with the ridge-line or anticlinal axis (a b in A) inclined.
In A the section is vertical; but to obtain from the measurement of the exposed
Fig. 108.
edges the true dip, it should have the direction of the arrows, that is, be at
right angles to the strike; for the layers fold over the ridge in this direction.
In II the section is very obliquely inclined: in C it is horizontal, and the edges
show nothing of the actual dip; in D the section follows the line of strike; in
E it is oblique behind: in F it is an oblique section on one side; and in G a
vertical section in the axial plane. All of these sections give wrong results to
the clinometer,—a section in the direction of the arrows in fig. A being the only
one in which the dip of the exposed edges is the dip of the layers or strata.
DISLOCATIONS OF STRATA.
109
If the axis of the fold make a very small angle with the horizon, then the two
sides in a horizontal section (such as may result from denudation) will be much
elongated (fig. 108 I), instead of short as in fig. C : and if the axis is horizontal
the two sides will not meet at all, and the fact of the existence of a fold is
not apparent. Even in the former case there might be difficulty in deter¬
mining the fact of a fold, if the part where the sides unite were concealed
from view by the soil or otherwise. But in each case there may be evidence of
a fold in the order of the beds in the two sides ; for this order on one side would
be just the reverse of that on the other. If. in fig. I. represent a coal or
iron-ore bed having its border d more impure than the rest, this border,
if it were on the east side in one half of the fold, would be on the west side
in the other half.
The difficulties in the way of correct observation on folded rocks are further
enhanced when the axial plane of the fold is inclined.—especially when it is
so inclined that both sides of the fold have the same dip (fig. 106 a). Still
closer study is required when several folds are irregularly combined, as is com¬
mon in nature.
This important subject may be further studied by uniting sheets of different-
colored card-board together, bending them into a fold, and then cutting them
through in different directions.
118. Distortions of fossils.—These uplifts of the rocks, besides
disturbing the strata themselves, cause distortion also in im¬
bedded fossils,—either (1) a flattening from simple pressure, or,
in addition (2), an obliquity of form, or else (3) a shortening, or (4)
an elongation.
The following figures, from a paper by D. Sharpe, illustrate some of these dis¬
tortions occurring in a slate rock in Wales. They represent two species of shells,
the Spirifer dixjunctus (figs. 1 to 4) and the Spirifer giganteux (figs. 5 to 8).
Fig. 1 is the natural form of S. dixjunctus ; the others are distorted. The lines
z z show the lines of cleavage in the slate : 2 lies in the rock inclined 60° to the
planes of cleavage, and is shortened one-half; 3 lay obliquely at an angle of 10°
or 15°; it is shortened above the middle and lengthened below it : 4 is a cast,
the upper part pressed beneath that shown, while the lower is much drawn out ;
5 is like 3, the angle with the cleavage-plane being less than 5°: the lower part
has lost its plications by the pressure and extension : 6 has a similar angle to the
cleavage-plane, but a different position ; 7 intersects the cleavage-plane at only
1°, and its lower part is very much prolonged. Compression, a sliding of the
rock at the cleavage-planes, and more especially a spreading of the rock itself
Fig. 108 I.
no
LITIIOLOGICAL GEOLOGY.
under the pressure, are the causes which have produced these distortions.
Univalves and all fossils are liable to become similarly misshapen under the
same causes.
Fig. 109.
119. Calculating the thickness of strata.—When strata are inclined, as
in fig. 110, the thickness is ascertained by measuring the extent
along the surface, and also the angle of dip, and then calculating the
Fig. 110.
thickness by trigonometry. The thickness of the strata from a to b
is b d, the line b d being drawn at right angles to the strata. Mea¬
suring a b, and the dip, which is the angle bad, the angles and hypo-
thenuse of the triangle a b d are given to determine one side b d. Or
with the distance a e the side c e would be found.
But it is important, for trustworthy results, that the absence of
faults be first ascertained. The figure (110) represents a fault at bg,
so that the strata 1, 2, 3, 4 to the left are repeated to the right;
and hence the whole thickness is b d instead of c e. There may be
many such faults in the course of a few miles; and each one would
increase the amount of error if not guarded against.
DISLOCATIONS OF STRATA.
Ill
120. It is seen from the figure that a single inclined stratum consisting of the
layers 1, 2, 3, 4 would have a surface-width (width at the earth's surface or on
a horizontal plane) of a b. But by means of the fault another portion is brought
up to the surface, and a b is increased to a c. So other faults might go on
increasing the extent of the surface-exposure. This is further illustrated in
fig. 111. Let A be a stratum 10,000 feet thick (a to e) and 100,000 feet long
(« to b). Let it now be faulted as in fig. B, and the parts uplifted to a dip
of 15°,—taking a common angle for the parts, for the sake of simplicity of
illustration. The projecting portions being worn off by the ordinary processes
of denudation, it is reduced down to fig. C, m n being the surface exposed to the
observer. The first error that might be made from hasty observation would
be that there were four distinct out¬
cropping coal-layers (calling the
black layer thus), instead of one ;
and the second error, the one above
explained with regard to calculating
the thickness of the whole stratum
from the entire length m n in con¬
nection with the dip. If the stratum
were inclined at 15° without fault¬
ing, it would stand as in fig. D;
and if then worn off to a horizontal
surface, the widest extent possible
would be cr,—less than half what
it has with the three faults. The
length of c r may be determined
from the thickness a c and the
angle of dip, the angles and one
side of the triangle being given to
find the hypothenuse. With a dip of 15° it would be less than four-tenths of a b:
with a dip of 30°, one-fifth of a b; with a dip of 45°, less than one-seventh.
It is plain also, without further explanation, that when a layer is
folded many times upon itself, as explained on p. 104, a large extent
of horizontal surface of tilted beds may be produced even when the
stratum thus folded has of itself little thickness.
121. Unconformable strata.—Another consequence of the tilting or
displacement of strata is this: that deposits are often laid down upon
the upturned edges of older rocks. Fig. 112 represents cases in which.
Fig. 112.
after the rocks below had been folded or upturned, other strata were
laid down at a 6 horizontally on the inclined beds, being thus uncon-
112
LITIIOLOGICAL GEOLOGY.
formable to tliose beds. Below e f there are really two sets of un-
corformable beds in a synclinal valley; and, moreover, the lower
strata were much faulted and upturned before the upper were laid
down upon them. The Connecticut River sandstone, like the
latter, lies in a synclinal valley of older rocks, is more or less faulted,
and is overlaid by horizontal alluvial beds.
There is here exemplified a method of arriving at the period or tune of
an uplift. In such cases of unconfor mobility, the upturning of the lower
beds must have taken place after they were made, and before the
deposition of the overlying beds. The time of the upturning, therefore,
was between the period to which the upturned rocks belong, and
that of the overlying deposits.
Deposits like tliosc at e f are true basin or trough deposits ; for they' are formed
in basins or depressions of the surface. Such deposits may, in general, he dis¬
tinguished by their thinning out towards the sides of the basin. Yet when
synclinal valleys are shallow it is easy, and not uncommon, to mistake beds
conformable with the strata below
for such basin-formations. The beds
a b (fig. 113) lie in the synclinal val¬
ley m 11 like a basin-deposit, though
not so. They were disconnected
from the stratum with which they
were once continuous, by denudation
over the anticlinal axes m and n. Hence the beds a b were formed before the
folding of the beds, and not after it.—an historical fact to be determined in all
such cases with great care.
4. Order of arrangement of Strata.
122. The true order of arrangement of strata is the order in
which they were made, or their chronological order.
Difficulties.—There are several difficulties encountered in the
attempt to make out such an order. The stratified rocks of the
globe include an indefinite number of limestones, sandstones,
shales, and conglomerates; and they occur horizontal and dis¬
placed, conformable and unconformable, part in America and part
in Europe, Asia, and Australia, here and there coming to view,
but over wide areas buried beneath soil and forests.
Moreover, even the same bed often changes its character from
a sandstone to a shale, or from a shale to a limestone or a con¬
glomerate, or again to a sandstone, within a few scores of miles,
or, if it retains a uniform composition, it changes its color so as
not to be recognized by the mere appearance. Again, some
strata are of very limited extent, while others spread widely over a
continent.
Fig. 113.
ARRANGEMENT OF STRATA.
113
Again, a stratum of one age may rest upon any stratum in
the whole of the series below it,—the Coal measures on either
the Azoic, Silurian, or Devonian strata; and the Jurassic, Creta¬
ceous, or Tertiary on any one of the earlier rocks, the intermediate
being wanting.
In addition, denudation and uplifts have thrown confusion among
the beds, by disjoining, disarranging, and making complex what
once was simple. In the United States, many a sandstone in New
York and Pennsylvania is represented by a limestone in the Ohio
and Mississippi valleys,—that is, the two were of cotemporaneous
origin; some rocks in eastern New York are not found in the
western part of that State, and some in the central and western
not in the eastern. The Post-Tertiary in America in some places
rests on Azoic, in others on Silurian or Devonian, in others on
Cretaceous or Tertiary. And, if so great diversity of condition
exists in one country, far greater may be expected between dis¬
tant continents.
Amidst all these sources of difficulty, how is the true order ascer¬
tained ?
123. Means of determination.—It is plain from the preceding
remarks that the true method cannot consist in grouping rocks of
a kind together, as limestones, shales, or sandstones. It is irre¬
spective of kinds, and is founded on a higher principle,—the
same which is at the basis of all history,—successiveness in events.
The following are the means employed.
(1.) Order of superposition.—When strata are little disturbed, ver¬
tical sections give the true order in those sections and afford
valuable information. Or where the strata outcrop over the surface
of a country, the succession of outcro]:>ping layers affords a section,
and often one of great range. The vertical extent of such a section
may be ascertained as explained in $ 119. In using this method by
superposition, several precautions are necessary.
Precaution ls£.—Proof should be obtained that the strata have not
been folded upon one another, so as to make an upper layer in any
case a lower one in actual position (see p. 107),—a condition to be
suspected in regions where the rocks are much tilted, but not where
the tilting is small.
Precaution 2d.—It should be seen that the strata under examina¬
tion are actually continuous.
A fault in the rocks may deceive; for it makes layers seemingly
continuous which are not so. In some cases, beds forming the
upper part of a bluff (as a b, fig. 114) have settled down bodily
(c) to the bottom, so as to seem to be continuous with the older
9
114
LITHOLOGICAL GEOLOGY.
ones of the bottom (as c with <-/). In one instance a mistake was
thus made with respect to the age of a human relic, which a
little care might have avoided. In other
cases, caverns in rocks have been filled
through openings from above, and the
same kind of mistake made. When the
continuity can be established, the evi¬
dence may sometimes lead to important
results. For example, it may be found
that a coal-bed followed for some miles
to one side or the other is continuous with
a clay shale, and both are actually one layer; that a sandstone is
one with a limestone a few miles off; that an earthy limestone full
of fossils is identical with a layer of white crystalline marble in a
neighboring district; or that a fossiliferous shale of one region is
the same stratum with the mica schist of another.
Precaution 3c/.—Note whether the strata overlie one another con¬
formably or not.
Precaution 4th.—When one bed overlies another conformably, it
does not follow necessarily that they belong to consecutive periods.
The Tertiary beds may rest conformably on any stratum from the
Cretaceous to the Silurian. A range of conformability so conti¬
nuous is not, however, usual ; for disturbances of the strata have
been so common in past time that the later rocks are seldom con¬
formable to the older. Among rocks comparatively near in age,
however, it is common to find strata wanting, without any break
in the conformability.
The criterion mentioned, unless connected with others, gives no
aid in comparing the rocks of distant or disconnected regions. For
this purpose other means must be employed.
124. (2.) Color, texture, and mineral composition.—This test may be
used to advantage within limited districts, yet only with caution.
There were at one time in geology an "old red sandstone" and a
"new red sandstone," and whenever a red sandstone was found it
was referred at once to one or the other. But now it is well under¬
stood that the color is of little consequence, except within a small
geographical range. The same general remark holds with reference
to mineral composition.
One inference from the constitution of a stratum is safe; that is,
that the stratum is more recent than the rock from which its mate¬
rial was derived. Hence an imbedded fragment of some known
rock may afford important evidence with regard to the age of the
containing stratum.
Fig. 114.
ARRANGEMENT OF STRATA.
115
It is common to judge of the age of igneous rocks by their composition; but
it is an unsafe criterion. Some use may be made of it hereafter in settling cases
that remain doubtful, but not until the age of the greater part of such rocks
has been ascertained on evidence of a better kind than this. In the case of
metamorphic rocks of different ages it may prove of value when their dis¬
tinctive peculiarities are thoroughly known.
125. (3.) Fossils.—This criterion for determining the chronological
order of strata takes direct hold upon time, and, therefore, is sure
and sufficient. The life of the globe has changed with the progress of time.
Each epoch has had its peculiar species. Moreover, the succession of
life has followed a grand law of progress, involving under a single
system a closer and closer approximation in the species, as time
moved on, to those which now exist. It follows, therefore, that
Identitg of species of fossils proves approximately identity of age.
The change has not consisted in a change of species alone, but
also in certain grand modifications of type or structure. Thus, for
fishes there are both ancient and modern types; and in most
of the classes there are great groups which belong to the past and
mark the progressing ages,—as Trilobites mark the Palaeozoic,
Sigillariae the Coal period, Ammonites and flying reptiles the
Reptilian age. Hence the canon may have the broader form,—
Identity of type or family in organic forms proves identity of age.
The canon is a universal one. Had we a table containing a list
of the complete series of rocks, and of the families, genera, and
species of fossils which each contains, it would be a key for the
rocks of the whole world,—South and North America as well as the
Orient; and by comparing the fossils of any rock under investi¬
gation with this key, the age would be approximately ascertained.
This is the method now pursued in studying the geology of the
globe. The key is, in fact, already so complete that it is constantly
appealed to by the geological observer. The list which is made
for the Silurian and Devonian rock^ in New York State is used
for identifying the strata of the Mississippi basin; and that
which has been prepared in Europe is constantly employed to
make out the true synchronism between the rocks of the two
continents.
By such comparison of fossils it was discovered that the Chalk
formation exists in the United States, although there is no chalk
on the continent; that the Coal formation of North America and
that of Newcastle, England, belong to the same geological age;
and so in numberless other cases of identity between the strata
of distant continents.
The commencement in the preparation of such a key was attended
116
LITHOLOGICAL GEOLOGY.
with much difficulty. In New York State it was necessary—first to
study all the sections in the eastern, central, and western parts, and
determine carefully the fossils in each stratum ; then to compare
the sections with one another: when any case of identity in the
fossils among these strata of the different sections was observed,
it was set down as one horizon determined. By this method, and
other aid from observing the continuity of beds, one horizon after
another was ascertained, and the strata between were arranged
according to their true order of succession.
There are precautions required in the use of this key, depending
on individual differences in the continents and diversities in the
range of fossils, which will be better understood after a review of
the general progress of life on the globe.
126. Subdivision into Ages.—By the means explained, great
progress has been made in arranging the rocks of the different
continents in a chronological series. North America has some
large blanks in the series, which in Europe are filled; and in this
way various countries are contributing to its perfection. This
series has been divided into Ages, based on the progress of life,
as follow:—
I. Azoic Age (from a, privative, and C,uov, animal).-—Containing no
traces of animal life.
II. Silurian Age, or Age of Mollusks.—Mollusks the dominant
race.
III. Devonian Age, or Age of Fishes.—Fishes the dominant
race.
IV. Carboniferous Age, or Age of Acrogens.—Characterized by
coal-plants, or Acrogens.
Y. Reptilian Age.—Reptiles the dominant race.
VI. Mammalian Age.—Mammals the dominant race.
VII. The Age of Man.
The subdivisions are given.beyond.
127. Thickness of the stratified rocks.—The whole thickness of
the rocks in the series has been stated at fifteen or sixteen miles.
But this includes the sum of the whole grouped in one pile. As
the series is nowhere complete, this cannot be said to be the thick¬
ness observed in any one region. The rocks of New York, down
to the Azoic, counting all as one series, are about 13,000 feet in
thickness. They include only the Silurian and Devonian (except¬
ing the Triassic in the southeast). To the north they thin out
to a few feet, while they thicken southward towards Pennsyl¬
vania. In Pennsylvania the rocks include the Carboniferous,
and the whole thickness is at least 40,000 feet. This is exclusive
UNSTRATIFIED CONDITION.
117
of the Triassic, which may add a few thousands to the amount.
In Virginia the thickness is still greater; but no exact estimate
has been made. In Indiana and the other States west it is only
4000, although extending, as in Pennsylvania, to the top of the
Carboniferous. The greater part of the continent of North Ame¬
rica east of the Mississippi is destitute of rocks above the Carboni¬
ferous.
In Europe the rocks of the later periods are far more complete
than in North America, while the older also, according to the
estimates stated, exceed the American. In Great Britain the
thickness to the top of the Carboniferous is over 60,000 feet, and
from the Carboniferous to the top of the series little less than
10,000 feet more. This amount is the sum of the thickest deposits
of the several formations, and not the thickness observed in any
particular place.
2. UNSTRATIFIED CONDITION.
128. The larger part of the crystallized rocks are sedimentary
rocks altered or crystallized by heat or other means; and they are,
therefore, not true examples of unstratified rocks. In general they
still retain the lines of deposition distinct. When gneiss and mica
schist are found in alternations with one another, it is plain that
each layer corresponds to a separate layer in the original deposit,
and the beds, although crystalline, are still as really stratified as
they ever were.
In some metamorphic rocks, however, the appearance of stratifi¬
cation is lost; and such may be properly said to be unstratified.
Yet it should be understood that the name does not imply that
they never were stratified, but that this is now their apparent con¬
dition. Granite and syenite are unstratified rocks of this kind. In
much granite there is no lamination, no arrangement of the con¬
stituent minerals in parallel planes, no evidence of subdivision
into layers. But even this true granite, a few miles off, may become
a schistose or gneissoid rock, and, a short distance farther on,
by gradual transition, a gneiss in which a schistose structure is
very distinct.
Examples of the unstratified condition are common among true
igneous rocks. The ridges of trap or dolerite which range in lofty
masses over many districts—as the Palisades on the Hudson, Mounts
Tom and Holyoke and other trap ridges of the Connecticut valley,
the trap of the Giants' Causeway and of Fingal's Cave—are some
of these examples. The rocks were melted when they came up
to the light through fissures, and they now stand without any
118
LITIIOLOGICAL GEOLOGY.
marks of stratification. The sketch below represents a scene
among rocks of this kind in Australia. The dome-shaped masses of
Fig. 115.
Basaltic columns, coast of Illawana, Now South Wales.
trachyte in some regions of ancient volcanoes, and the interior mass
of many great volcanoes,—sometimes exposed to view through rend-
ings of the mountain or denudation by water,—are also examples.
But the ordinary outflows of liquid rock from volcanoes usually
produce layers, which are covered afterwards by others in succession;
and volcanic mountains, therefore, have to a great extent a strati¬
fied arrangement of the rock-material, and not less perfectly so
than bluffs of stratified limestone. Moreover, the same rock which
forms the Giants' Causeway may in other places be interstratified
among sandstones and shales; for the layer of igneous outflow,
wherever it takes place, may be followed afterwards by deposits
of sand or other sediment.
129. Another example of unstratified material is found in the
loose pebbles and stones wrhich cover a large part of the northern
half of both the American and European continents. Any ordi¬
nary mode of action by water lays down sediments in layers. But
these accumulations—often called drift—are of vast extent and
without layers. Wherever the same kind of material is in layers,
it is then said to be stratified; and thus it is distinguished from the
unstratified.
There may, therefore, be both stratified and unstratified sedi¬
ments, and stratified and unstratified igneous rocks ; and by the
obliteration of the planes of deposition by metamorphism there
may be unstratified metamorphic rocks like granite, as well as
stratified.
130. On the subject of the structure of these rocks, it is only
necessary to refer to the ordinary massive structure of granite
UNSTRATIFIED CONDITION.
119
and trachyte, etc., and to the columnar structure met with among
igneous rocks. The last is represented in the figure given above.
There are all shades of perfection in this columnar structure, from
prisms of great height with perfectly plane sides, to a mere ten¬
dency to split in prismatic forms ; and also from this less perfect
prismatic character, to the massive structure with no trace of
columnar fracture.
For a continuation of this subject, see the chapter on igneous
operations, under Dynamical Geology.
131. (1.) General nature of veins.—The vein condition.—Veins are
narrow plates of rock intersecting other rocks. They are the fill¬
ings of cracks or fissures ; and, as these cracks or fissures may either
extend through the earth's crust to the interior and divide it
for long distances, or reach down only for a limited depth, or be
confined to single strata, so veins are exceedingly various in extent.
They may be no thicker than paper, or they may be scores of
rods in width, like the great fissures opened at times to the earth's
inner regions by subterranean agency. They may be clustered
so as to make a perfect net-work through a rock, or may be few
and distant. And, as strata have been faulted, so veins also may
have their faults or displacements. All those subterranean move¬
ments that produce joints and fractures in rocks may give origin
to veins.
(2.) Subdivisions.—Veins are divided into dikes and proper veins.
Dikes are filled by volcanic rocks, basalt, trap, or some other ig¬
neous rocks, and have regular and well-defined walls.
Veins are occupied by quartz, granitic rocks, metallic ores,
calcite, fluor spar, heavy spar, etc.,—ingredients which are less ob¬
viously a liquid injection from Deiow, and probably never of this
nature. They are generally irregular in form, often indistinct in
their walls, and very varying in their ingredients. They abound
in regions of metamorphic rocks. Veins have been subdivided
into kinds; but the divisions need not here be considered.
Fig. 116.
Fig. 117.
120
LITHOLOGICAL GEOLOGY.
(3.) Forms and faults of veins and dikes.—Fig. 116 represent?
two simple veins or dikes (« n and b b) intersecting stratified rocks.
Fig. 117, a net-work of small veins.
Fig. 118.
Fig. 119.
Fig. 118, small veins of quartz intersecting gneiss,—the mass five feet square.
The veins do not all cross one another, and correspond to the cracks which
result from contraction, as by sun-drying or cooling, rather than to those of
any other mode of Assuring.
Fig. 119. Two veins a presenting some of the common irregularities of
mineral veins in size, the enlarged parts containing mostly the ore: a is faulted
by another vein b, which is of subsequent formation.
Fig. 120.
Figs. 120, 121, 122. Examples of granitic veins of very large size in a
gneissoid granite, showing their subdivisions and various irregularities (taken
UNSTRATIFIED CONDITION.
121
by the author from granitic rocks near Valparaiso). The veins undergo con¬
stant changes of size, and in some places encircle masses of rock resembling
Fig. 121. Fig. 122.
the rock outside. The rock adjoining the vein is more micaceous than that at
a distance, and the direction of the lamination (as indicated in the figures) varies
with some reference to the intersecting veins, curving approximately parallel
to the veins on two opposite sides m and n, and not at all so on the other two
o and/). The subdivisions of the veins in fig. 121 cross one another in an alter¬
nate manner, a cutting cl and e but cut by c, and b cut by c, d, and e; and in
122, although the veins are similar in constitution, one cuts the other ; and in
120 the two crossing veins are broken and subdivided at the intersection so as
to appear like one vein stretching off in two directions like a letter X.
Fig. 123.
Fig. 123. A vein a faulted by b,—whence it is inferred that b is subse¬
quent to a in age. Also a vein 1 faulted by 2 and again by 3, and 3 faulted
Fig. 124. Fig. 125. Fig. 126. Fig. 127.
by 4: 2 and 3, therefore, were subsequent in age to 1, and 4 was subsequent to 3.
The faulting is exhibited also in the layers of the stratified rocks which the
veins intersect.
122
LITHOLOGICAL GEOLOGY.
Figs. 124, 125, 126. Veins much broken or faulted: in 124, four faults within
a length of eighteen inches; in 125, six faults in six feet; in 126, the broken
parts of the vein of unequal breadth.
Fig. 128. Fig. 129.
Figs. 127, 128, 129. Other faulted veins, 127 a and b, six feet apart, and still
different in their faults; 128, 129, other interrupted veins. These dissimilarities
between the parts of one faulted vein, as in 126, and between the parts of two
parallel veins, as in 127, arise from an oblique shove of the parts either at the
time of the fracturing in which the veins themselves originated, or at some
subsequent fracturing.
The points here illustrated are,—
The great irregularities of size in veins along their courses,
swelling out and contracting ; their occasional reticulations ; their
frequently embracing portions of the enclosed rock; their nume¬
rous faultings or breaks and displacements.
132. (4.) Structure.— Dikes.—Dikes consist essentially of the
same kind of material from side to side and at all heights, where not
altered by exposure to the air. The structure may be simply
massive, or cracked irregularly, as in many volcanic dikes. But
frequently there are transverse fractures, producing a columnar
structure, so that a dike is like a pile of
columns. For a short distance from the
walls the structure is generally imperfect
(fig. 130) ; and in many cases there is an
earthy layer along the sides, or even a lami¬
nated structure parallel with the walls
(fig. 131), produced by the friction of the
rising liquid mass against the walls of the
fissure.
133. Veins never have the transverse columnar structure of
dikes. The simplest consist of one kind of material,—as quartz,
granite, heavy spar,—and are alike from side to side. But others
have a banded structure not found in dikes, consisting in an
arrangement of the material parallel to the walls. Fig. 132
represents such a vein, consisting of eleven bands: 1, 3, and 6 are
Fig. 130. Fig. 131.
f||p3l
fasi
pSpSfl!
l§8Kli
UN STRATIFIED CONDITION.
123
bands of quartz; 2, 4, of a gneissoid granite; and 5, of gneiss.
Of banded veins, the simplest is a vein with three bands, one
central; but the number may be a score or
more.
Instead of being simply rock-material, as in
fig. 132, the bands may be partly metallic ores
of different kinds, and calcite, heavy spar, fluor
spar, may make the alternating bands instead
of granite or gneiss. A great vein at Frei¬
berg consists of layers of blende, quartz, fluor
spar, pyrites, heavy spar, calcite, each two or
three times repeated, the layers nearly corre¬
sponding on either side of the middle seam.
Thus this banded structure is as much cha¬
racteristic of veins as the columnar structure is of dikes: each
fails of the peculiarity in their simpler kinds.
The bands of a vein are far from uniform at different heights,
even when the width of the vein is constant; and they vary exceed¬
ingly through the contractions and expansions which take place at
intervals. The expanded portions may alone be banded, or consist
of layers parallel to the sides, or contain ore.
The mineral or rock-material accompanying the ore in a vein is
called the vein-stone, or gangue. The most common kinds of vein¬
stone are quartz, calcite, barytes, and fluor.
In studying veins, besides noting their extent, mineral cha¬
racter, and structure, it is important to ascertain their strike and
angle of dip. There is generally an approximate uniformity of
strike in a given region; and frequently the direction is parallel to
the principal line of elevation in the region. The nature of the
walls or adjoining rock, and systems of faults, are other points that
should receive close attention.
134. False veins.—Besides the veins and dikes described, there
are also false veins. These false veins are fissures filled by sand
or clay from above. They are readily distinguished by the sedi¬
mentary nature of the material; for all true dikes or veins
are occupied by crystalline rocks or minerals. In a similar
manner earth and organic remains may be washed into caverns
or any open spaces in rocks, and so make, in the very body
of an old record, a false entry. Such a conjunction of com¬
paratively modern fossils with more ancient may lead to error,
unless the facts are carefully studied and the true explanation
ascertained.
Fig. 132.
65 43212 4 56
n:u*i in-, i", iHi
nil?
4
i1
li!
124
LITHOLOGICAL GEOLOGY.
In the language of miners,—
A lode is a vein containing ore.
The hanging wall of a vein is the upper wall when the vein has an oblique
dip; and the opposite is the foot-wall.
The fluecan is the half-decomposed rock adjoining a vein; and a thin, clayey
layer along either side of a vein is called the selvage.
A-horse is a body of rock, like the wall-rock, occurring in the course of a
vein.
A comb is one of the layers in a banded vein,—so called especially when its
surface is more or less set with crystals.
PART III.
HISTORICAL GEOLOGY.
GENERAL DIVISIONS IN THE HISTORY.
1. Nature of subdivisions in history.—The methods of ascer¬
taining the true succession or chronological order of the rocks
have been explained in §§ 122-125, and in connection (§ 126) a
brief mention is made of the grander divisions of the series. Some
further explanations are necessary as introductory to the survey
of geological history.
What are subdivisions in history ?—Many persons, in their study of
geology, expect to find strongly-drawn lines between the ages, or
the corresponding subdivisions of the rocks. But geological his¬
tory is like human history in this respect. Time is one in its
course, and all progress one in plan.
Some grand strokes there may be,—as in human history there is
a beginning in man's creation, and a new starting-point in the
advent of Christ. But all attempts to divide the course of progress
in man's historical development into ages with bold confines are
fruitless. We may trace out the culminant phases of different
periods in that progress, and call each culmination the centre
of a separate period. But the germ of the period was long Avork-
ing onward in preceding time, before it finally came to its full
development and stood forth as the characteristic of a new era of
progress. It is the same with the development or history of an
individual being. There are distinct epochs and periods in the
history which all recognize,—the period of the embryo, of the youth,
of the adult. But no one thinks of marking the hour or day
when one ends and another begins, or of pointing to a visible
physical line that at any given moment was passed. It is all one
progress, while successive phases stand forth in that progress.
In geological history, the earliest events were simply physical.
125
126
HISTORICAL GEOLOGY.
While the inorganic history was still going on (although finished
in its more fundamental ideas), there was, finally, the intro¬
duction of life,—a new and great step of progress. That life,
beginning with the lower grades of species, was expanded and ele¬
vated through the creations of new types, until the history closed
in the appearance of Man. In this organic history there are suc¬
cessive phases of progress, or a series of culminations, with the
creation of Man and Mind as the last and loftiest of these culmi¬
nations. As the tribes, in geological order, pass like panoramic
scenes before us, the reality of one age after another becomes
strongly apparent. The age of Mammals, the age of Reptiles, and
the age of Coal-Plants come out to view like mountains in the
prospect,—although if the mind should attempt to define precisely
where the slopes of the mountain end as they pass into the plain
around, it might be greatly embarrassed. It is not in the nature
of history to be divided off by visible embankments ; and it is a
test of the true philosopher to see and appreciate the culmina¬
tions of phases in time, or of the successive ideas in the system
of progress, amid the multitude of events and indefinite blendings
that bewilder other minds.
We note here the following important principles:—
First. The reality of an age in history is marked by the culmina¬
tion of some new idea in the system of progress.
Secondly. The beginning of an age will be in the midst of a pre¬
ceding age ; and the marks of the future coming out to view are to
be regarded as prophetic of that future.
Thirdly. The end of an age may be as ill defined as its beginning,
although its culminant point may stand out boldly to view.
Thus, the age of Coal-Plants was preceded by the occurrence of
related plants far back in the Devonian. The age of Mammals
was foreshadowed by the appearance of mammals long before, in
the course of the Reptilian age. And the age of Reptiles was pro¬
phesied in types that lived in the earlier Carboniferous age. Such
is the system in all history. Nature has no sympathy with the art
which runs up walls to divide off her open fields.
But the question may arise, whether a geological age is not, after
all, strongly marked off in the rocks. Rocks are but the moving
sands or the accumulations of dead relics of the age they represent,
and are local phenomena, as already explained. Each continent
has its special history as regards rock-making: and it is only
through the fossils in the rocks that the special histories are com¬
bined into a general system. Movements have in all ages disturbed
one hemisphere without affecting the other, causing breaks in the
SUBDIVISIONS IN THE HISTORY.
127
succession of rocks in one continent or part of a continent that
have no representatives in another.
When an age can be proved, through careful study, to have been
closed by a catastrophe or a transition which was universal in its
effects, the event is accepted as a grand and striking one in geo¬
logical history. But the proof should be obtained before the uni¬
versality is assumed. Hence the conclusion,—
Fourthly. The grander subdivisions or ages in geological history,
based on organic progress, should be laid down independently of the
rocks. They are universal ideas for the globe. The rocks are to be
divided off as nearly as practicable in accordance with them.
Each continent, under these ages, then becomes a special study ;
and its history has its periods and epochs which may or may not
correspond in their limits with those of the other continents. Every
transition in the strata, as from limestone to sandstone, clay-beds,
or conglomerate, or from either one to the other, and especially
where there is also a striking change in the organic remains, indi¬
cates a transition in the era from one set of circumstances to an¬
other,—it may be a change from one level to another in the conti¬
nents, a submergence or emergence, or some other kind of catas¬
trophe. All such transitions mark great events in the history of
the continent, and thus divide the era into periods, and periods
into epochs, and epochs, it may be, into sub-epochs. Hence,—-
Fifthly. Through the ages each continent had its special history ;
and the periods and epochs in that history are indicated by changes
or transitions in the rock-formations and their fossils.
It is greatly to the assistance of research that some of the revolu¬
tions of the globe have probably been nearly or quite universal.
The one preceding the Mammalian age appears to be an example;
although, even with regard to this, further investigation is required
before its actual universality can be regarded as established. But
the periods and epochs of America and Europe are not in general
the same in their limits. A near cotemporaneity in rocks may be
proved, but not in the transitions from one rock to another. For
example, the Devonian age has a very different series of periods
and epochs in North America from what it has in Europe, and there
is even considerable diversity between the epochs of New York and
the Atlantic slope, and those of the Mississippi valley. The Car¬
boniferous, Reptilian, and Mammalian ages also have their American
epochs and their European, differing from one another; and the dif¬
ferences between the continents increase as we come down to more
modern times. There are Tertiary and Cretaceous rocks in America
as well as Europe, but there is little reason for the assumption that
128
HISTORICAL GEOLOGY.
the transitions from one set of Tertiary or Cretaceous strata to
another were, in the two, cotemporaneous. The point should be
proved, not assumed. We add, therefore,—
Sixthly. It is an important object in geology to ascertain as nearly
as possible the parallelism between the periods and epochs marked
off on each continent, and study out the precise equivalents of the
rocks, each for each, that all the special histories may read as parts
of one general history, and thus contribute to the perfection of one
geological system.
Progress of life as the basis of the subdivision into geo¬
logical ages.—The general principles in the progress of life upon
which the ages are based are shown in the annexed table.*
Age of Man.
Age of Mammals.
Ago of Reptiles.
Carboniferous Age.
Age of Fishes, or
Devonian.
Age of Mollusks,
or Silurian.
Azoic.
The horizontal bands represent the ages, in succession; the ver¬
tical correspond to different groups of animals and plants.
The Radiates begin with the Lower Silurian, and continue till
now, rather increasing throughout the ages.
The Mollusks have their beginning at the same time, and continue
increasing to the age of Reptiles; they then pass their maximum
(as indicated in the figure) and decline.
* The system of ages is essentially the same with that proposed by Professor
Agassiz,—the only difference consisting in calling the Silurian the age of Mol¬
lusks, instead of considering both the Silurian and Devonian the age of Fishes.
Fig. 133.
ANIMALS. PLANTS.
SUBDIVISIONS IN THE HISTORY.
129
The Articulates, as the table shows, commence in the Silurian
(as Crustaceans and Worms), and continue expanding in numbers
and grade to the present time.
Fishes begin in the Silurian, are very abundant in the Devonian,
and continue on, becoming increasingly diversified to the last, with¬
out much rise in grade.
Reptiles begin in the top of the Devonian, and reach their maxi¬
mum in the Reptilian age.
Mammals begin in the Reptilian age, and have their maximum in
the Mammalian age.
As to Plants, Sea-weeds (or Alga) are the earliest of the globe, pro¬
bably preceding animal life. The Acrogens begin in the Devonian,
or earlier, and have their greatest expansion in the age of Coal-
Plants, where they occur with abundant Conifers. Cycads begin
in the Carboniferous, and have their greatest expansion in the Rep¬
tilian age. Dicotyledons begin in the closing period of the Reptilian
age, and expand, along with Palms, through the age of Mammals.
The Silurian is eminently the age of Mollusks; for this is the
highest branch of the animal kingdom which is represented at that
time in all its grand subdivisions. Bracliiopods, Conchifers, Gas-
teropocls, Pteropods, Cephalopods, begin in the Lower Silurian, and
the Molluscan type is thus unfolded at the outset, while the Articu¬
lates are represented by only the inferior marine divisions, and the
Radiates, besides being an inferior type, are present only in the
lower tribes of its three classes. The age is eminently, therefore,
the age of Mollusks. Any fishes discovered in the Silurian would
foreshadow, in the manner explained, the age of Fishes, as the
Reptiles of the Carboniferous age foreshadowed the Reptilian age,
and the Mammals of the age of Reptiles the Mammalian age.
In the Devonian age, the Fishes, the lowest of Vertebrates, are
the dominant type. The Reptilian age is still more eminently an
age of Reptiles, and the Mammalian age an age of Mammals, as is
shown beyond in the survey of these ages.
On botanical data, the ages would be—-first, the age of Sea-urcds,
covering the ages of Mollusks and Fishes ; second, the age of Coal-
Plants or Acrogens, or the Carboniferous age ; third, the age of Cgcads,
corresponding to the age of Reptiles; and, fourth, the age of Palms
and Dicotyledons, corresponding to the Mammalian age. The only
addition to the preceding divisions based on the animal tribes
which is thence suggested by the vegetable kingdom is the Carboni¬
ferous. In the zoological series this might be called the age of Am¬
phibians, as it is characterized prominently by the amphibian division
of Reptiles.
10
130
HISTORICAL GEOLOGY.
The ages recognized are, then, Age of Mollusks, or Silurian; Age
of Fishes, or Devonian; Carboniferous Aye; Age of Reptiles; Age of Mam¬
mals; Age of Man.
Preceding these, there is the Azoic era,—the name being derived
from the Greek a and life, and signifying the absence of life.
The Azoic rocks are mostly crystalline.
The Silurian, Devonian, and Carboniferous ages naturally stand
somewhat apart from the following in the peculiar ancient forms of
the great portion of their living tribes, and to the whole collectively
the term Palaeozoic era is appropriately applied,—the word " palaeo¬
zoic" being from the Greek tta?Mior, ancient, and t^uov. The following
age, or age of Reptiles, is correspondingly termed the Mesozoic, from
/uecior, middle, and l,oov, it being the mediaeval era in geological history.
The Mammalian age is termed the Cenozoic, from naivvg, recent, and
Cuov. (The words Eocene, Miocene, etc., subdivisions of the age, are
in part from the same root.)
The subdivisions of geological time are, then,—
I. Azoic Time or Age.
II. Palaeozoic Time.
1. The Age of Mollusks, or Silurian.
2. The j\.gc of Fishes, or Devonian.
3. The Age of Coal-Plants, or Carboniferous.
III. Mesozoic Time.
4. The iVge of Reptiles.
IV. Cenozoic Time.
5. The Age of Mammals.
V. Eiia of Mind.
G. The Age of Man.
Subdivisions into Periods and Epochs.—The subdivisions under the ages,
the periods and epochs, vary, as has been said, in different countries.
The following table (fig. 134) presents a general view of those of
eastern North America, as far as the Palaeozoic is concerned,—the
Silurian, Devonian, and Carboniferous being well represented on the
North American continent. The rest of the series is from European
geology, in which the later ages are far better represented than in
America. In this manual, American geology is in general first con¬
sidered, and afterwards such further illustrations are drawn from
other continents as are necessary for comprehensive views anil
generalizations. Where America is deficient in its records, the
European are taken as the standard.
The names of the periods and epochs for the Paheozoic of Ame¬
rica are the same that have been applied to the rocks by the New
York geologists.
131
Permian.
Carboniferous.
Sub-carbonifer¬
ous.
Catskill.
Chemung.
Hamilton.
Trenton.
Potsdam.
Azoic.
Upper Coal Measures.
Lower Coal Measures.
Millstone Grit.
Upper.
Lower.
Chemung.
Portage.
Genesee.
Hamilton.
Marcellus.
Upper Helderberg.
Schoharie.
Cauda-Galli.
Orislcany.
Lower Helderberg.
Saliferous.
Niagara.
Clinton.
Medina.
Oneida.
Hudson River.
Utica.
f Trenton.
"j Black River.
(_ Birdseye.
Chazy.
Calciferous.
Potsdam.
Azoic.
132
HISTORICAL GEOLOGY.
Fig. 134 (continued).
Epochs and Sub-Epochs.
Pleistocene, or Post-tertiary.
Pliocene.
Miocene.
Eocene.
(Upper or White
Uppei Cretaceous. 4 Chalk.
(Lower or Gray.
Middle Cretaceous (Upper Green-Sand).
Lower Cretaceous (Lower Green-Sand).
Wealden.
Middle Oolite.
'-'•"'-'{Ct,.
Upper Lias.
Marlstone.
Lower Lias.
Keuper.
Muschellcalk.
Bunter-sandstein.
' Post-tertiary.
- j ~
2
1
Q Tertiary.
Ace of Man.
Wealden E.
Oolitic
Epoch.
Liassic
Epoch.
In the figures and maps introduced beyond, the numbers are used
as in the above tables: 1 standing for the Azoic; 2 for the rocks of
the Potsdam period, 2 a for the Potsdam epoch, 2 b for the Calci-
ferous sand-rock; 3 for rocks of the Trenton period, 3 a, 3 b, for the
epochs of this period ; and so on.
The following map of the United States east of the Rocky Moun¬
tains exhibits the geographical distribution of the rocks of the several
ages,—that is, the regions over which they are severally the surface-
rocks.
The Silurian is distinguished by heavy horizontal lining ; and the
dotted line over the Silurian area divides the Upper Silurian (w)
from the Lower Silurian (I).
134
AZOIC AGE.
The Devonian, by heavy vertical lines.
The Carboniferous, by light cross-lines on a black ground, or by a black
surface, or by dots on a black ground (the first the Sub-carboniferous,
the second the Coal formation, the third the Permian).
The Reptilian, including the Triassic, Jurassic, and Cretaceous, by
lines sloping from the right to the left (/), the Cretaceous being
distinguished by having the lines broken.
The Tertiary, by lines sloping from the left to the right f \ ).
The A zoic, by irregular line-dottings.
The surface without markings is occupied by rocks of undeter¬
mined age,, that on the east mostly crystalline.
I. AZOIC TIME OR AGE.
Reality of the Age.—The Azoic age is the age in the earth's his¬
tory preceding the appearance of animal life. The fact of the
existence of the globe at one time in a state of universal fusion
is placed beyond reasonable doubt. And whatever events occurred
upon the globe from the era of the elevated temperature necessary
to fusion, down to the time when the climate and waters had become
fitted for animal life, are events in the Azoic age. The age must,
therefore, stand as the first in geological history, whether science can
point out unquestionably the rocks of that age or not.
The fossils of true Palreozoic and Mesozoic rocks have often been obliterated
by the crystallization of these rocks; and, as the oldest rocks of the globe are
nearly all crystallized, the question may always arise with respect to any par¬
ticular one of them, whether it may not once have been filled with fossils. After
having reached what was thought to be the lowest fossiliferous beds in Great
Britain, fossils have been found in others inferior, carrying the Silurian down
to a still lower level by transferring to it what had been regarded as Azoic.
Such changes are part of the progress of the science, and cause little inconve¬
nience to the system, provided the order of succession be rightly given.
Stratigraphical limits in North America.—The Azoic rocks in
North America* at present include all that are older than the Pots¬
dam sandstone of New York,—the first of the Silurian. This sand¬
stone is spread out in nearly horizontal layers, conformable with the
overlying Silurian beds, but rests on crystalline rocks, which are
upturned at all angles and folded or crumpled on a scale of great
* The Azoic system of North America was first distinctly recognized in its
true importance in the Report of Foster & Whitney on the Lake Superior
region. The rocks inferior to the Silurian have been called by Murchison the
Bottom rocks. They are part of the primary of the old geologists.
GEOGRAPHICAL DISTRIBUTION.
135
extent. These beds, thus crystallized and flexed or disturbed before
the Potsdam sands were deposited, are the Azoic. The following
sections illustrate this point. In each, the Azoic, numbered 1, in its
usual disturbed condition, is overlaid nearly horizontally by the
Silurian beds, 2 a being the Potsdam sandstone, 2 b the Calciferous
sandrock, 3 the Trenton limestones, 4 a the Utica shale.
Fig. 136. Fig. 137.
v,
\.n--XN
v~
1 2a 2 b 1 la
la
Fig. 138.
2a
i
4 a
3
ih
m
vi
/
Fig. 13G, by Emmons, from Essex CO., N.V.; 1 is liyperstlienu rook, or hypunto.—Fig. 137,
by Owen, from Black Biver, south of Lake Superior; 1 is a granitic rock, 1 a, cliloritie and
ferruginous slates.—Fig. 138, by Logan, from the south side of the St. Lawrence in Canada,
between Cascade Point and St. Louis Rapids; 1, gneiss.
Geographical distribution.—The Azoic rocks constitute the only
universal formation. They cover the whole globe, and were the
floor of the oceans and the rocks of all emerged land when animal
life was first created. But subsequent operations over the sphere
have buried the larger part of the ancient surface, and to a great
extent worn away and worked up anew its material; so that the
area of the old floor now exposed to view is small.
The areas of the earth's crust over which the Azoic rocks are now
exposed are either,—
1. Those which have always remained uncovered.
2. Those which have been covered by later strata, but from
which these superimposed beds have been simply washed away,
without much disturbance.
3. Those once covered, like the last, but which, in the course
of the upturnings of mountain-making, have been thrust upward
among the displaced strata, and in this way have been brought out
to the light.
In cases like those of figures 136, 137, in which the Silurian
rocks are spread in nearly horizontal layers over the borders of
an area made up of tilted Azoic rocks, the Azoic area either has
been always uncovered, or has become so from denudation; but
in mountain-regions where the Silurian rocks have been folded
up in the mountain-making, the Azoic below may have been brought
13G
AZOIC AGE.
up to view in the same process. Moreover, the Azoic, if it had not
undergone flexures before the Silurian beds were laid down, would
partake of the Silurian flexures, or, in other words, be conformable
to the Silurian strata. But if it had been flexed or tilted in some
previous period of disturbance, then the Azoic would be unconform¬
able to the Silurian, although both were finally upthrown together
in the making of the mountains.
In the study of Azoic regions these points require special investi¬
gation.
The Azoic areas of North America of the first kind (and partially,
it may be, of the second) are shown, as far as now ascertained, on the
accompanying map of the Azoic continent. The Azoic lands on this
Fig. 139.
Azoic Map of North America.
chart are represented as the dry land of the era, while the rest of
the continent is submerged. They are concluded to have been thus
dry, because no marine beds cover them, while, on either border,
marine beds (Silurian and later) commence and spread widely over
the most of the continent. The outline of the continent and of the
GEOGRAPHICAL DISTRIBUTION.
137
great lakes enables the reader to perceive the relative positions of
these Azoic lands. There may have been other areas along the
Appalachians, and over the Rocky Mountain region, which future
study will bring to light.
The Azoic regions laid down are—
1. Canada north of the St. Lawrence, reaching northeast from
Lakes Huron and Superior to Labrador (C C), and the continuation
northwest (B B) to the Arctic Ocean.
2. An isolated area in northern Hew York,—a peninsular pro¬
longation, it may be considered, of the Canada region,—covering for
the most part Essex, Clinton, Franklin, St. Lawrence, Hamilton,
and Warren cos., and part of Saratoga, Fulton, Herkimer, Lewis,
and Jefferson cos.
3. A similar area south of Lake Superior (S).
4. West of the Mississippi, a small area in Missouri, in which the
famous Iron Mountains are situated; the Black Hills in Dakota,
and the Laramie Range in Nebraska, as recently observed by Dr.
Hayden ; part of the Ozark Mountains in Arkansas.
In northern New Jersey there are Azoic gneiss, limestone, and other crystalline
rocks containing "great beds of the ore called Franklinite, analogous to the iron-
ore beds of northern New York: the lowest Silurian beds cover them un-
eonformably. Professors Rogers have described the occurrence of Azoic rocks
in the Appalachians; but, although probably occurring in the range, the evi¬
dence is not yet conclusive that the rocks so designated antedate the Silurian.
Professor Safford mentions rocks of the Azoic age in eastern Tennessee,—a
part of the same mountains; but they are stated to b e conformable, as far as yet
investigated, to the Silurian.
The map of New York and Canada in the chapter on the Silu¬
rian shows more precisely the form of the New York Azoic and
that north of the St. Lawrence. It represents also the Silurian
and Devonian strata of the State as they become successively the
surface-rocks on going from the Azoic southward. Adjoining the
Azoic (numbered 1) is the earliest Silurian, No. 2, which outcrops
where it is represented, but is supposed to underlie the strata num¬
bered 3, 4, 5, etc. So No. 3 is the next formation which outcrops,
while it probably underlies all the beds 4, 5, etc. The Azoic is thus
the basement, and each successive stratum was a new deposit over
it in the seas that bordered at the time the Azoic dry land.
In Europe the Azoic system has been distinctly recognized in
Norway and Sweden and in Bohemia underlying the Silurian
unconformablv. The great iron-regions of Sweden are probably
of this age. In geological maps of other parts of the world
(and those of Europe and America are not always excepted) it is
138
AZOIC AGE.
common to color the regions covered by crystalline rocks all alike,
without reference to their differences of age. Thus the metamor-
phic rocks of various ages are confounded, as they are also in the
unfortunate name they sometimes bear, of hypogene rocks.
Kinds of rocks.—The rocks are mostly of the metamorphic
series, related to granite, gneiss, syenite, and the like. But they
embrace only the most ancient of these rocks ; for the granites
and schists of New England, of Cornwall, the Alps, and many
other regions, belong to later ages.
Besides true granite and gneiss, there are dionte,—a rock consisting
of feldspar (albite) and hornblende without quartz (§ 84); also
extensive ranges of coarse granite-like rocks of grayish and
reddish-brown colors, composed mainly of crystallized labradorite
or a related feldspar (§ 55), or of this feldspar with the addition
of the brownish-black and bronzy foliated mineral hypersthene
(§65), and constituting the rock called hyperite ; also chlorite schist,
while mica schist appears to be absent; also serpentine, limestone
(or statuary marble), granular quartz (a hard sandstone), and in
some places a hard conglomerate; also magnetic and specular iron-ore in
immense beds.
There are, in addition, porphyry of green, brown, and reddish colors; a
garnet-euphotide (eclogite) and a feldspar-euphotide (§85); soapstone (Rens-
selaerite) (§ 86, [4]); parophite rock and schist (§§ 67, 87); pyroxene rocks;
ophiolites or verd-antique marble of different varieties (§86, [8]).
Part of the feldspar related to labradorite has the composition of andesine
or vosgite; and oligoclase exists in the Swedish Azoic. The Labrador rock
turns gray on weathering. Part of the hyperite contains ordinary hornblende
instead of hypersthene, and some kinds mica or epidote. The hypersthene is in
foliated pieces or crystals often a little bronze-like in lustre. Good localities for
the opalescent labradorite are the streams of the Adirondack,—especially, says
Professor Emmons, the beaches of East River; also Avalanche Lake, near the
foot of the great slide from Mount McMartin.
The potstone or soapstone called Rensselaerite covers considerable areas in
the towns of Fowler, Canton, Edwards. Hermon, etc., St. Lawrence co., and
at Grenville, in Canada, and is cut into slabs for tables, chimney-pieces, fur¬
nace-linings, or made into inkstands. The parophite or aluminous potstone
of Diana, Lewis co., N.Y. (§ 87), is also used for inkstands, etc.
Beautiful red and green porphyry and a buhrstone are found at Grenville,
Canada.
As crystalline rocks have been formed in various ages,—those
of New England, for example, long after those of the Azoic,—it is
possible that some Azoic rocks have undergone a second or third
alteration subsequent to the original one in the Azoic age. It may
be difficult, in fact, to say which of the rocks retain their original
CHARACTERISTICS OF AZOIC ROCKS.
139
composition. There is, however, no reason to suspect any funda¬
mental changes in the granitic or hornblendic rocks or schists.
But the potstones, both magnesian and aluminous, are probably
of later origin. The Rensselaerite has been observed under the
crystalline form of pyroxene, showing that in part, at least, it has
been made out of pyroxene; and the aluminous species exists
under the crystalline form of nepheline, giving unequivocal proof
that it has been made out of pre-existing nepheline crystals, like
the gieseckite of Greenland, which it resembles in aspect and com¬
position. The rocks are probably, therefore, the result of the altera¬
tion of different minerals or rocks after the first Azoic crystalli¬
zation. If this be true, they may not be actually Azoic rocks : they
may belong to the same age with the metamorphic rocks of New
England, or to some other period. By one interested in bringing
the events of geological history into their true chronological rela¬
tions,—the real end in geological studies,—this will be regarded as
an important question.
Other evidences of alteration since the original crystallization in
northern New York have been observed,—such as the rounded
quartz crystals of Gouverneur, and the soft spinels of St. Lawrence
co., called houghite. Even the serpentine of the same region may
come into this category.
Minerals of the Azoic rocks.—Besides the constituent minerals mentioned,—viz.,
quartz, feldspar of different species, hornblende, pyroxene, epidote, mica, talc,
garnet,—there are also the following common species : tourmaline, scapolite,
wollastonite, sphene, rutile, graphite, the mica called phlogopite ($ 56), apatite,
cljondrodite, spinel, zircon, corundum,—each of which occurs at times in the
crystalline limestone or its vicinity. Mica is found in Grenville, Canada, in
plates between one and two feet square. In addition to these, there are a
number of rare ores of yttrium, cerium, and columbium among the Swedish
Azoic rocks.
No gold, has thus far been found in the Azoic. Andalusite, kyanite, and
staurotide are also among the common minerals of crystalline schists not
detected in the Azoic.
Characteristics of the Azoic rocks.—1. The Azoic rocks are
nearly all crystalline rocks. A few sandstones, slates, and conglo¬
merates are the only exceptions; and these are excessively hard
rocks.
2. The crystalline rocks are remarkable for the small amount
of silica they contain (a fact noticed by T. S. Hunt). This is
seen in the absence of quartz from many of the rocks (the cliorite,
Labrador rock, hyperite), and the abundance of feldspars, like
labradorite, that have a low proportion of silica.
140
AZOIC AGE.
3. The prevalence of iron is another characteristic (remarked by
J. D. Whitney). This is seen in the abundance of the minerals
(silicates) containing iron, as hornblende, hypersthene, chlorite,
garnet; also the reddish color of much of the feldspar; also the
beds of iron-ore, which exceed in extent those of any other age.
4. There are none of the simple silicates of alumina.
Arrangement of the rocks.—Although the Azoic rocks are
mostly crystalline, they follow one another in various alternations,
like the sedimentary beds of later date. In the sections which have
been given, there are alternations of granite, gneiss, schists, lime¬
stone, etc.; and the dip and strike may be studied in the same
manner as in the case of any tilted sandstones or shales. The
following sections represent other examples; and in them there are
beds of iron-ore, one hundred feet and upwards in thickness, which
are banded with siliceous layers and chloritic schist, showing
thereby a distinctly stratified character. Where most flexed or
folded, there is still a distinction of layers; and it is owing to this
fact that the rocks may be described as folded; for folds can be
identified only where the rocks are in sheets. This grand fact is,
then, evident,—that the Azoic rocks are in layers, as much as the
rocks of any later age.
The following section by Logan (real in its general truths, although partly
ideal) exhibits well this fact. It presents to view a stratum of (a) white
Fig. 140.
granular or crystalline limestone, many times folded, and interstratified with
gneiss and quartz rock (b); and over the same region (Grenville and adjacent
country, Canada) the limestone has been traced in linear and curving bands
corresponding to a series of folds.
The following sections contain iron-ore beds among the alternations. In
Fig. 141. Fig. 142. Fig. 143.
p
j§|
a a b
i i i
fig. 141 (from the Michigan region, Foster A Whitney) the iron-ore, in extensive
beds (i, i), occurs between chloritic schist (a, «) and diorite (6); and the iron-
ARRANGEMENT OF AZOIC ROCKS.
141
ore in i is banded with jasper. In figs. 142 and 143 (Essex co., N.Y.,
Emmons) the iron-ore, in beds several yards wide, is associated with gneiss
and quartz rock, and is interlaminated with
quartz, the whole dipping together in a
common direction, like beds of sandstone,
shale, and iron-ore in many regions of sedi¬
mentary rocks.
In fig. 144 (Penokie Range, south of Lake
Superior, C. Whittlesey) h is hornblende rock
and slaty quartz; y, quartzite, 30 feet thick;
i, a bed of iron-ore, 25 to 50 feet thick.
In another section, by C. Whittlesey (described in Foster & Whitney's Report),
taken at the falls of the Menomonee, there are alternations of gneiss, horn¬
blende, and quartz rock with talcose and chloritic schists, quartzite, and granu¬
lar limestone, and between the limestone layers there is a layer of iron-ore,—
showing again that the iron-ore is in beds conformable with the schists. The
beds, however, may not have great lateral extent; for the iron may be local in
bands, or imbedded in other kinds of rocks.
In the Missouri region, at Pilot Knob, the ore-strata (says J. D. Whitney)
consist of a series of quartzose beds of great thickness, passing gradually into
specular iron, which frequently forms bands of nearly pure ore, alternating
with bands of quartz more or less mixed with the iron. The ore, moreover,
is often thin-laminated. '
At the Adirondack mines, in Essex co., N.Y., one bed, according to Emmons,
is 150 feet thick, and another exceeds 700 feet. In the Michigan region they
are on the same great scale. In Missouri, one of the " iron mountains"—the
Pilot Knob—is 581 feet high, and the other 228 feet; and huge displaced
masses, some ten and twenty tons'weight, lie over the surface. The iron-ore in
each of these regions is partly magnetic and partly specular ore, or hematite,—
that of Lake Superior and Missouri mostly the latter, and that of New York
mainly the former.
In Canada, at Bay St. Paul's, there is a bed of titanic iron 90 feet wide,
exposed for 200 or 300 feet, occurring in syenite with rutile or oxyd of tita¬
nium. The ore does not differ from ordinary specular iron in appearance, but
the powder is not red. In Sweden and Norway the iron-ores are interstrati-
fied in the same manner with crystalline rocks,—mainly gneiss, hornblende
rocks, talcose and chloritic schists, argillaceous schists, quartzite, and granular
limestone, with which they are more or less laminated. At Dannemora, the
stratum containing iron is 600 feet in width; and it occurs with granular
limestone, talcose and chloritic schists, and gneiss. At Uto, Sweden, red,
jaspery quartz bands the ore, in the same way as in Michigan; the ore—the
specular mixed with the magnetic—occurs in mica schist and quartzite, in an
irregularly-shaped mass, about 120 feet in its widest part. At Gellivara there
is an iron mountain three or four miles long and one and a half wide, consist¬
ing mostly of magnetic iron-ore, with some specular ore. In each of these
regions the beds dip with the enclosing rock,—showing that all have had a
common history.
In the annexed sections (St. Lawrence co., N.Y., Emmons), granular lime-
Fig. 144.
142
AZOIC AGE.
stone is represented in connection with granite and other rocks. In fig. 145,
I is limestone, without any appearance of stratification; and the containing
rock is granite. In fig. 146, a a are gneiss, b steatite, I unstratified limestone.
Fig. 145. Fig. 146.
Although a and b are not evenly stratified, yet they are sufficiently so to show
that the limestone, while it has lost its division into layers in the crystallizing
process, is probably a conformable stratum.
The order of stratification among the Azoic rocks is as various as
among the rocks of other ages. As sandstones, shales, argilla¬
ceous sandstones, conglomerates, follow one another in any succes¬
sion, so granite or gneiss may lie between layers of slate or schist,
and quartz rock may have any place in the series. It is common,
however, to find the different hornblendic rocks associated toge¬
ther ; and both these and the chloritic often abound in the iron-
regions, since hornblende and chlorite are ferriferous minerals.
Again, chloritic schists are apt to accompany serpentine; since
chlorite is a hydrous magnesian species.
Again, as we recede from a granite region we sometimes find the
rocks less and less perfectly crystalline, passing from the granite
to the gneissoid, from these to the schistose, and last to those least
crystalline and containing water, as talcose and chloritic schist
and serpentine. But there are numberless exceptions to such an
order.
The Azoic rocks of Canada are divided by Logan into the Laurentian,—
including the great part of the system, and embracing all the regions to which
we have above particularly alluded,—and the Huronian, comprising a narrow
band on the borders of Lake Superior and Lake Huron. The Huronian are
thus separated because they have been found to rest unconformably upon the
Laurentian. They consist of siliceous slates, schists, quartzite, conglomerates,
and limestones. The conglomerates contain pebbles and boulders (some a foot
in diameter), which are derived in part from gneiss or syenite of the subjacent
Azoic, and thus show their later origin. Others contain pebbles of jasper and
quartz very firmly cemented. The sandstones are described also as bearing
ripple-marks. These rocks occur on Lake Temiscaming and on the north shore
of Lake Huron. No similar rocks have been observed to the eastward of these
districts, over all Canada to Labrador; and if ever there, they have been re¬
moved by denudation. The Huronian rocks are intersected by numerous dikes
of trap, and interstratified and overlaid by the same rock. The total thickness
of the formation, according to Logan, is over twelve thousand feet. The iron-
DISTURBANCES OF AZOIC BEDS. 143
ore region of Marquette, in Michigan, has been referred to the Huronian.
Should these Huronian rocks he found hereafter to contain any fossils, they
would form the first member of the Silurian.
According to Hunt, no talcose or chloritic schists occur among the Lauren-
tian rocks.
Original condition of the Azoic beds.—The alternations of argil¬
laceous, chloritic, and other schists with quartzites, limestone,
gneiss, and the other Azoic rocks, prove that all were once sedi¬
mentary beds,—beds formed by the action of moving water, like
the sandstones, argillaceous beds, and limestones of later times.
They have no resemblance to lavas or igneous ejections. The
schists graduate into true slates, and the quartzites into unmistak¬
able sandstones and conglomerates; so that there is direct proof in
the gradations as well as the arrangement in alternating layers
that all the schistose and siliceous rocks are parts of one series
of sedimentary beds which by some process have been hardened
and crystallized. Moreover, from the gneiss there is as direct a
passage to the gneissoid granite, and thence to true granite and
syenite ; so that even the most highly crystalline rocks cannot, as
a general thing, if at all, be separated from this series. These
Azoic rocks, therefore, are made out of the ruins of older Azoic,—
that is, of the sands, clays, and stones gathered and deposited by
the ocean as it washed over the earliest-formed crust of the globe.
Whenever the ocean took its place upon the cooling globe, the
conflict began, and sedimentary beds were the result; and the
original crust is now so disguised amid these later crystallized depo¬
sits, which are here called Azoic, or is so buried beneath them, that
geology can hardly expect to identify any portion of it. The loose
material transported by the currents and waves was piled into
layers, as subsequently in the Silurian, Devonian, and Carboni¬
ferous ages, and vast accumulations were formed ; for no one esti¬
mates the thickness of the recognized Azoic beds as below fifteen
or twenty thousand feet. Limestone strata occurred among the
alternations ; and argillaceous iron-ores, like the beds of the Coal
measures, though vastly more extensive, were a part of the forma¬
tions in the deposits.
The beds, moreover, were spread out horizontally, or nearly so ;
for this is the usual condition with sediments and limestones when
first accumulated. The original condition, then, of the Azoic rocks
was the same as that of ordinary sediments,—in horizontal beds
and strata.
Disturbances and Foldings.—But, from the sections and de¬
scriptions on the preceding pages, it is apparent that horizontal
144
AZOIC AGE.
Azoic rocks are now exceedingly uncommon. The whole series
has been upturned and flexed, broken and displaced, until little,
if any, of it remains as it was when accumulated.
This upturning, moreover, is not confined to small areas, nor has
it been done in patchwork-style; for regions of vast extent have
undergone in common a profound heaving and displacement.
This community of action or history is evident in the fact that the
rocks have nearly a common strike (§113) over wide regions,—the
strike being at right angles, or nearly so, to the action of the force
causing the uplift.
The strike in the New York, Canada, Michigan, and Lake Superior Azoic
is generally from the northeastward to the southwestward, or nearly parallel to
the course of the Appalachians and Green Mountains or the line of the present
Atlantic coast.
In the New York region, according to Professor Emmons, the course of the
line of limestone from Johnsburg to Port Henry, on Lake Champlain, is nearly
northeast; that of another, along by Rossie (between Black Lake and Pitcairn,
and from Theresa nearly to Lisbon and Madrid), north-northeast; another, paral¬
lel to this, extends from Antwerp to Fowler and Edwards. These outcrops of
limestone follow the line of strike; for the strike of the gneiss is in general
from southwest to northeast, or parallel to the general course of the highlands,
and therefore of the uplifts. The dip varies from 10° to 90° either side of the
perpendicular. The iron-ore beds have the same strike ; for all together con¬
stitute one system.
In Canada, the limestone ranges of the township of Grenville have the course,
according to Logan, between northeast and north-northeast, and mostly the
latter. The strike of the gneiss and schists has the same general course. The
Azoic near Lake Superior appears to have the same mean strike.
This uniformity of direction attests to a uniformity in the direction or action
of the uplifting force, as above remarked. The strike of the Azoic rocks of
Scandinavia is also to the northeastward, with no greater variations than occur
in the American Azoic; and this common course there, whether connected or not
with that on the opposite side of the Atlantic, indicates some vast comprehensive
agency as the origin of the disturbance.
The beds were laid down as sediments over immense continental
areas; and then followed a period of uplift, when the horizontal
layers were pressed into folds and displaced on the grand scale ex¬
plained. Many such periods of uplift may have previously occurred.
But it is evident that uplifting and disturbance were not the prevail¬
ing condition of Azoic times, any more than they were of later
ages. This is proved by the conformability of the various Azoic
beds to one another in this system of foldings. An age of com¬
parative quiet, allowing of vast accumulations of horizontal strata,
must have preceded the epochs of revolution.
LIFE OF THE AZOIC AGE.
145
Evidences of different epochs of revolution—that is, of uplift—may hereafter be
detected in the Azoic ; but thus far no definite progress has been made towards
this end, excepting in the separation of the Huronian proposed by Logan.
Alterations: Solidification and crystallization.—Besides the
universal displacements, there was an almost universal crystalliza¬
tion of the old sedimentary beds and limestones ; and now, in place
of the sands and clays and earthy limestone layers, the rocks are
crystallized into granite, gneiss, syenite, granular limestone, etc.,
by the solidifying process, and thus have lost almost every trace of
their original sedimentary aspect. The once massive and earthy
limestones now contain in many places crystals of mica, scapolite,
apatite, spinel, etc., in place of their old impurities, and the lime¬
stone itself is a white or variegated architectural marble. The
argillaceous iron-ore has become the bright specular and magnetic
ores, and it is banded by, or alternates with, schist and quartz, etc.,
which were once accompanying clay and sand layers.
Granite, syenite, and hyperite, although they present no lines of stratification
or foliation, are embraced among the metamorphic rocks as an actual part of
the series; for the slight difference of structure between them and gneiss is no
evidence of difference of origin. Whatever crystals they contain besides their
own crystalline grains,—as of pyroxene, garnet, sphene, wollastonite, horn¬
blende, feldspar,- -all were due to the same system of alteration.
The upturning may have brought up also the granites, syenites, and other
rocks of a previous metamorphic period, or some of the nether granitic rocks
belonging to the first-formed crust; but there is no means at present recognized
for distinguishing them ; and in many places the distinct alternation of the gra¬
nite or syenita with the gneiss and schists proves beyond doubt their eotem-
poraneous origin, at the last great Azoic revolution, out of a common series of
sedimentary strata. That this revolution preceded the Silurian age is known
from the fact that the Silurian beds overlie them unconformably.
It is remarked on a preceding page that some of the Azoic rocks
may have undergone a second or third alteration during the follow¬
ing ages, and that the magnesian and aluminous potstones and
part of the serpentine and its associated minerals may be among
these later products. The mind that has any adequate appre¬
hension of the remoteness of that Azoic era will not question the
probability of such changes, and is ready to wonder rather that
the evidences of subsequent alterations are not more extensive and
obvious.
Life of the Azoic Age.—The term "azoic," as here used, implies
absence of life, but not necessarily of the lowest grades.
The reasons in favor of the existence of life of some kind are—
1. The formation of limestone strata in the Azoic age like those
11
146
AZOIC AGE.
of the Silurian, in connection with the fact that Silurian and later
limestones are known to be mainly made from organic relics.
2. The occurrence of graphite in the limestone and other strata,
—graphite being known to he a common result of the exposure
of mineral coal or charcoal to a high heat, and, in certain rocks
of Rhode Island and Massachusetts, having undoubtedly been made
from vegetable remains.
3. The occurrence of anthracite in small pieces in the iron-
bearing rocks of Arendal, Norway, which rocks are probably Azoic
in age.
Against this organic origin it may be urged that the limestones
and graphite may have been of chemical origin; and in the earlier-
age of the globe, when there existed a heat too great for animal
life, the occurrence of such chemical formations is not improbable:
yet the argument still leaves it an open question.
Supposing the existence of life of some kind, it is more likely to
have been vegetable than animal.
1. In the progressing refrigeration of the globe, a temperature
fit for vegetable life would have been reached before that which
animal life could sustain. If there is any exception to this, it is to
be found only among the lowest species of animal life; and there
is as yet no evidence that such exceptions exist.
2. The graphite and anthracite indicate vegetable life, if any
at all.
3. There are among the Azoic rocks, slates, sandstones, quartz-
ites, and conglomerates which are not more altered than some
Silurian rocks containing fossils; and, had Mollusks and Crinoids
existed, shells and Encrinites should be found in the beds. More¬
over, the great beds of iron-ore rarely contain a trace of phos¬
phates ; and this is some indication that there was little or no
animal life.
4. The Silurian formation commences with the same genera and
partly with the same species of animal life in different parts of Eu¬
rope and America,—indicating that the actual bottom of the series
of animal life had been reached alike in both countries.
5. Again, in America a period of folding and crystallization
appears to have terminated the Azoic age, making a fitting close
to the era of the earth's primal inorganic history. The latter part
of this long time of revolution (whose centuries may have been
counted by scores) was the epoch of the unfossiliferous Huronian
beds,—since these terminate the Azoic, according to Logan. They
indicate, as far as studied, no existing animal races.
6. It is possible that vegetable life may make strata of lime-
ANIMAL KINGDOM.
147
stone. There are coral-secreting plants as well as animals; and
such plants are called Corallines. There are also microscopic in¬
fusorial plants; and those secreting silica—the siliceous infusoria
(Diatoms)—are known in later times to have made extensive beds
of rocks. Limestone beds have been made from the microscopic
Rhizopods; for chalk is largely due to their growth and accumu¬
lation. And these Rhizopods, although animal, are extremely low
in the scale,—little above the spores of sea-weeds: so that, if exist¬
ing then, they simply foreshadowed the future animal kingdom.
Whenever the earliest plant, however minute, was created, then
the grand idea of life first had expression, and a new line of pro¬
gress in the earth's history was announced.
Relations of the North American Azoic to the continent.—
The map, fig. 139, cannot be examined without perceiving at once
the following striking facts :—
That the great Azoic area of the continent has (1) its longer leg,
B B, parallel approximately to the Rocky Mountains and Pacific;
and (2) its shorter, C C, parallel to the Appalachian Range and the
Atlantic; that—
(3) The peninsula of Florida is nearly in the course of the Pacific
branch, B B; and (4) the Missouri and Arkansas Azoic regions (MA)
are nearly in the course of the Atlantic branch, C C.
(5.) That the northwest side of Lake Superior and the Azoic of
the Black Hills lie in the same line.
Such are some of the structure-lines of the continent in this its
early or Azoic state. They are features that were never afterwards
effaced : instead of this, they were manifested in every new step
in the progress of the continent.
[From this point the progress of the life of the globe is a pro¬
minent part of geological history. A brief review of the system
of life is therefore here introduced, together with some of the
details respecting those of the subdivisions that characterize the
Silurian age.]
1. ANIMAL KINGDOM.
In the Animal Kingdom there are four Sub-Kingdoms, based on
four distinct types of structure, each having its system of subdi¬
visions of several grades or ranks. These sub-kingdoms are as
follow, beginning with the lowest:—
I. Radiates.—Having a radiate structure, like a flower or a star,
internally as well as externally. The animals have a mouth and
148
ANIMAL KINGDOM.
stomach for eating and digestion, and hence they are widely
diverse from plants.
The figs. 147 to 156 represent examples of Radiates: 147, an
Actinia, or Polyp; 148, 149, living corals, the animals of which are
polyps ; 150, a Medusa, or Acaleph,—also called Jelly-fish,—showing
well the internal as well as external radiate structure, as the animal
is nearly transparent; 151, 152, polyp-like species of the class of
Acalephs; 153, an Echinus, or Sea-urchin,—but not perfect, as the
spines which cover the shell and give origin to the name Echinus
are removed from half its surface to show the shell; 154, a Starfish ;
155, 156, Crinoids,—animals like an inverted Star-fish or Echinus,
Figs. 147-156.
Radiates, figs. 147-156. 1. Polyps: Fig. 147, an Actinia; 148, a coral, Dendrophyllia; 149, a
coral of the genus Gorgonia. 2. Acalephs: 150, a Medusa, genus Tiaropsis; 151, Hydra
(X8); 152, Syncoryna. 3. Echinoderms: 153, Echinus, the spines removed from half
the surface (X 154, Star-fish, Pabeaster Niagarensis; 155,Crinoid,Encrinusliliiformis;
156, Crinoid, of the family of Cystids, Callocystites Jewettii.
standing on a stem or pedicel, like a flower. Fig. 157 is the shell
of another Sea-urchin; and fig. 158, another Crinoid. Figs. 523
to 535 are additional examples of Radiates.
The radiate feature exists not only in the external form, but also
in the interior structure. The mouth, when furnished with cal¬
careous jaws or mandibles, has a circle of five of them; and the
nervous system, when distinct, is circular in arrangement.
II. Mollusks.—The structure essentially (1) a soft, fleshy bag,
MOLLUSKS.
149
containing the stomach and viscera, (2) without a radiate structure,
and (3) without articulations. The animals of the Oyster and Snail
are examples. In some kinds there are eyes and arms, but the
arms or appendages are never jointed; and in this the species are
distinct from Articulates.
Figs. 157-159.
Radiates.—Fig. 157, an Echinus without its spines,—the Clypeus Hugi of the Oolite: 158,
the living Pentacrinus Caput-Medusse of the West Indies (X 34)' a> C c' *4 outline of the
stem of different species of Pentacrini; 159, plates composing the body of a Crinid, Acti-
nocrinus longirostris Hall.
Figs. 160 to 168 represent some of the kinds of Mollusks. Figs.
160, 163, 164, 165, are shells of different species; 166, the shell of a
snail, with its animal; 168, another shell, the Nautilus, with its
animal; 162, a magnified view of a minute coral, with the living ani¬
mals projecting from the cells, which, although apparently radiated
like a polyp, are still Mollusks, because this radiation is only exter¬
nal, as is apparent in fig. 162 a, which represents one of the animals
taken out of the cell and more magnified. Fig. 169 is another
Mollusk,—a Cephalopod,—having some resemblance to the Radiates
in the position of the arms, but none beyond this.
The name Mollusk is from the Latin mollis, soft. The shells are
for the protection of the soft, fleshy bodies.
III. Articulates.—Consisting (1) of a series of joints or segments,
and (2) having the viscera and nervous cord in the same general
cavity, but (3) having no internal skeleton : as Worms, Crustaceans,
Insects.
150
ANIMAL KINGDOM.
The articulations are made in the hardened skin, and not, as in
Vertebrates, in internal bones; and the principal nervous cord
Figs. 160-168.
Mollusks, figs. 160-168.—1. Brachiopods: 160, Terebratula impressa, of the Oolite; 161
Lingula, on its stem. 2. Bryozoa : 162 (X 8), 162 a, genus Eschara. 3. Conchifers, or
Common Bivalves: 163,164; 165, the Oyster. 4. Gasteropods : 166, Helix. 5. Pteropods:
167, genus Cleodora. 6. Cephalopods: 168, Nautilus (X %)■
Fig. 169.
The Calamary or Squid, Loligo vulgaris (length of body, 6 to 12 inches); i, the duct by
which the ink is thrown out; p, the " pen."
passes below the stomach and intestine, and has usually a ganglion
in each segment of the body,—so that the articulate structure is in¬
dicated by the nervous system as well as by the joints of the body and
its members. The fundamental element of the body is, hence, a
segment or ring containing a nervous ganglion and a portion of the
viscera. In some worms the segments are so far independent that
the animals multiply by spontaneous fission.
VERTEBRATES.
151
Some of the Articulates are shown in figs. 170 to 179. Fig. 170 is
a sea-shore worm; 171, a Crab ; 172 to 177, other Crustaceans ; 178,
Figs. 170-179.
an Amphipod, species of Orchestia; 174, an Isopod, species of Serolis (X?/>); 175, 170,
Sappbirina Iris; 175, female, 176, male (X 6); 177, Trilobite, Calymene Blumenbachii;
17S, Cythere Americana, of tbe Cypris family (X 12); 179, Anatifa, of the Cirriped tribe.
another Crustacean, having a shell like a Mollusk, but showing
that it is a true Articulate in having its legs and antennae jointed,
as well as the body within the shell; 179, representing a Cirriped,
is also somewhat like a Mollusk in its shell,—though articulate in
structure, as the legs show, and, in fact, a Crustacean. Centipedes,
and all Insects, as well as Worms, are other examples of Articulates.
The name of the sub-kingdom is from articulus, a joint.
IV. Vertebrates.—Having (1) a jointed internal skeleton, and
(2) a bone-sheathed cavity along the back for the great nervous
cord, distinct from the cavity for the viscera: as in Fishes, Reptiles,
Birds, Quadrupeds.
The skeleton is made up of vertebrae, or the bones of the verte¬
bral column, with their appendages; and a vertebra is the funda¬
mental element of the structure. The bone-sheathed cavity occu¬
pied by the nervous cord is enclosed by processes from the upper
(or dorsal) side of the vertebrae, and the visceral cavity by the
ribs, which are processes from the lower side of the vertebrae.
The legs and arms are appendages to the system of vertebrae and
ribs.
Recapitulation.—In Radiates the structure is radiate or flower¬
like. In Mollusks it is bag-like and simple. In Articulates it is
made of a series of rings, and is composite both in the structure
of the skeleton and the nervous system. In Vertebrates it is made
152
ANIMAL KINGDOM.
of a series of vertebrae, and is hence composite in the skeleton
but essentially simple in the nervous system.
Y. Protozoans.—Besides the species above included, there are
others, of extreme simplicity of structure, which are sometimes re¬
ferred to the Radiates and sometimes to a separate group, called
Protozoans (from rfpuroj, first, and £7ooi>, animal). They embrace some
of the mkroscopic organisms or animalcules, and also the Sponges.
They have, in general, no proper mouth or stomach.
Radiates, Mollusks, Articulates, and Protozoan^are Invertebrates.
Subdivisions of the Sub-Kingdoms.
[Details relating to the higher groups are given as follow: Fishes,
p. 277 ; Peptiles, p. 343 ; Mammals, p. 421.]
I. Vertebrates.
Four classes are generally recognized : —
1. Mammals.—Species suckling their young, — a characteristic
peculiar to this highest branch of the animal kingdom: all are
warm-blooded and air-breathing. Examples: ordinary Quadrupeds,
large and small, with Whales and Seals.
2. Birds.—Warm-blooded and air-breathing; oviparous ; covered
with feathers, and adapted for flying.
3. Peptiles.—Cold-blooded, air-breathing; oviparous ; skin naked
or covered with scales, as the Crocodile, Lizard, Frog.
4. Fishes.—Cold-blooded ; breathing by means of gills; skin naked
or covered with scales.
II. Articulates.
The classes are three in number,—one of them—Insecteans (in¬
cluding Insects, Spiders, and Myriapods—aerial in respiration ; the
other two including Orustaceayis and Worms, which breathe by means
of gills, and live in water or moist earth.
A. Respiration through breathing-holes (sjnracles) along the sides
or posterior part of the body; admitting air to circulate in the
interior. Essentially land or aerial species.
1. Insecteans.—(1). Insects.—The body in three parts,—a head, tho¬
rax, and abdomen distinct; only three pairs of legs. Examples: the
Beetle, Wasp, Fly, Butterfly.
(2). Spiders.—The body in two parts, the head and thorax not dis¬
tinct; four pairs of legs. Examples: the Spider, Tick, Scorpion.
(3). Myriapods.—The body worm-like in form, the head not promi¬
nently distinct from the rest; legs numerous. Examples: the Cen¬
tipede.
CRUSTACEANS.
153
B. Respiration aqueous or by means of gills,—unless the species is
so minute that the surface of the body is equivalent to a gill in its
action. Essentially water-species, living either in water or moist
places.
■£. Crustaceans.—The body in two parts,—an anterior, called the
cephalothorax, consisting of a head and thorax, the posterior called
the abdomen ; locomotion by means of jointed organs. Examples: the
Crab, Lobster, Shrimp.
3. Worms.—Worm-like in form, without any division into cephalo¬
thorax and abdomen ; the body fleshy ; no jointed legs, though
often furnished with tubercles, lamellae, or bristles. Examples: the
Earth-worm, Leech, Serpula, Intestinal Worm.
The water-species of Articulates commence in the Silurian, and
are here further explained.
Crustaceans.—Among Crustaceans there are three orders:—
TlieyA.s/, or highest, ten-footed species, or Decapods; as Crabs (fig.
171) and Lobsters.
The second, fourteenfooted species, or Tetraclecapods (figs. 172, 173,
174).
The third and lowest, irregular in number of feet, and unlike
the Tetradecapods, also, in not having a series of appendages to
the abdomen: the species are called Entomostracans, from the Greek
for insects with shells.
(a.) Among the Decapods, Crabs arc called Brachyurans,—from the Greek for
short-tailed, the abdomen being small and folded up under the body; the Lob¬
sters and Shrimps, Macrourans,—from the Greek for long-tailed, the abdomen
being as long as the rest of the body.
(6.) Among the Tctradecajiods, figs. 172, 174 represent species of the tribe of
Isopods (a word meaning equal-footed), and fig. 173 of that of Amphipods (feet
of two kinds, abdominal as well as thoracic). Fig. 172 is the Sow-bug, com¬
mon under stones and dead logs in moist soil. Fig. 174 is the Sand-flea, abun¬
dant among the sea-weed thrown up on a coast. In figs. 172, 174 (Isopods),
the abdomen is abruptly narrower than the cephalothorax; its appendages
underneath are gills. In fig. 173 (Amphipod) the abdomen is the part of the
body after the eighth segment; its appendages are swimming legs and stylets,—
the gills in the Amphipods being attached to the bases of the true legs, and not
to the abdomen.
(c.) Among Entomostracans the forms are very various. The absence of a
scries of abdominal appendages is the most persistent characteristic. The eyes
in a few species have a prominent cornea; but in the most of them the cornea
is internal and there is no projection. In the Cyclops group the species have
often a shrimp-like form, as in fig. 175, though usually minute. Sometimes the
male and female differ much in form : 176 is male and 175 female of the Sapphi-
rina Iris; a h is the cephalothorax, and h d the abdomen. There are legs on
154
ANIMAL KINGDOM.
the under surface of the anterior part, fitted for grasping, and others behind
these, for swimming. In the Caligus group the species resemble 170, but the
mouth is trunk-shaped and movable. In the Cypris group the animal is con¬
tained in a bivalve shell, as in fig. 178, and they are hence called Ostrctcoids. They
are seldom a quarter of an inch long. In the Daphnia group the body has a
bivalve shell as in Cypris, but the shell does not cover the head or close at the
margin. In the Limulus group—containing the Horseshoe of the sea-coasts of the
United States—there is a broad, shield-like shell, and a number of stout legs, the
basal joints of which serve for jaws. In the Phyl/opod group the form is either
shrimp-like, approaching Cyclops, or like Daphnia or Cypris; but the append¬
ages or legs are foliaceous and excessively numerous : the name is from the Greek
for leaf-like feet. In the Cirriped or Barnacle group the animal has usually a
hard, calcareous shell, and is permanently attached to some support, as in the
Anatifa (fig. 179) and Barnacle. The animal throws out a number of pairs of
slender jointed arms looking a little like a curl, and thus takes its food,—
whence the name, from the Latin cirrus, a curl, and pes, foot. The Anatifa
has a fleshy stem, while the ordinary Barnacle is fixed firmly by the shell to
its support.
Trilobites.—The Trilobites (fig. 177, and also 245 and 320, 322),
which occur only fossil, have a resemblance both to the Entomos-
tracans and the Tetradecapods. The similarity to fig. 174 (a Serolis)
among the latter is apparent; but they are supposed to be still
nearer the Entomostracans, and especially the group called Phyl-
lopods, in which the legs are thin-foliaceous and very numerous,—
for no remains of legs are found with any Trilobites, which would
not be the case if they had had the stout legs common to Crus¬
taceans of the same size. It is possible that the abdomen (c d,
in fig. 177) had, beneath, a series of appendages; and, if so, they
differed from all known Entomostracans, and approximated to the
Tetradecapods. The division of the body longitudinally into three
lobes, to which the name trilobite refers, is in some species very in¬
distinct, and there is in no case more than a mere depression and
suture.
In the Trilobite the shell of the head-portion (a b, fig. 177) is usually called
the buckler; the tail- (or properly abdominal) shield, when there is one (fig. 320),
the pygidium. The buckler (« b) is divided by a longitudinal depression into
the cheeks, or lateral areas, and the glabella, or middle area (fig. 177). The cheeks
are usually divided by a suture extending from the front margin by the inner
side of the eye to either the posterior or the lateral margin of the shell. In
fig. 177 (Calymene Blumenbachii) this suture terminates near the posterior outer
angle. The glabella may have a plane surface, or be more or less deeply trans¬
versely furrowed (fig. 177), and usually with only three pairs of furrows.
Worms.—-Worms are divided into—
(1.) Dorsibranchiat.es, or free sea-worms, having in general short branchial
appendages along the back. Many swim free in the open sea, and others live in the
MOLLUSKS.
155
sands of sea-shores or the muddy bottom. The Arenicola family includes species
that burrow in the sands of sea-shores. Fig. 170 represents the .1. pi sea tor urn, or
Lob-worm, which is common on European shores, and grows to the size of the
linger. One species of Eunice has a length of four feet.
(2.) The Tubicola, or Serpula tribe, which live in a calcareous or membranous
tube and have a delicate branchial flower, often of great beauty, near the head.
They are confined to salt water. The tubes often penetrate corals, and the
branchial flower comes out as a rival of the coral polyps around it.
(3.) The Terricola (Oligochseta), or Earth-worm tribe, destitute of branchial
appendages ; as the common Earth-worm.
(4.) The Suctorin, or Leech tribe; sucking-worms; as the Leech.
Besides these there are the Helminths, including most Intestinal worms, and
the Turbellaria.
III. Mollusks.
The Ordinary Mollusks are usually divided into—
(1.) The Acephals, or headless Mollusks; as the Oyster and Clam;
(2.) The Cephalates, having a head; as the Snail; and,
(3.) The Cephalopods, having the head furnished with feet; as the
Cuttle-fish.
The headless species have a mouth, but no perfect organs of
sight; the Cephalates have distinct eyes and a distinct head (fig.
166) ; the Cephalopods have the eyes large, and can grasp with
great power by means of their arms (fig. 169). These arms corre¬
spond to mouth-appendages or palpi (feelers) in other Mollusks.
The fleshy body of Mollusks has on either side a loose skin or
fleshy leaflet starting from the back, which covers the sides of the
body like a cloak, and is either open or closed along the venter: it
is called the mantle ox pallium (cloak). This mantle lies against the
shell in the oyster, clam, and allied species, and secretes it; and in
the univalves it is reflexed over more or less of the exterior of
the shell, and performs the same function. It enables the animal
to give the ornament in color and form which is found over the
exterior of many univalves.
1. Cephalopods, or Cuttle-fish tribe.—The shells of this tribe
are distinguished almost invariably by having transverse partitions,
—whence they are called chambered shells (fig. 168). They may be
either straight or coiled; but with few exceptions they are coiled
in a plane, instead of being spiral. ' A tube, called a siphuncle,
passes through the partitions; and this siphuncle may either
be central or nearly so, as in the genus Nautilus (fig. 168), or lie
along the inner or ventral side of the cavity, or the outer or dorsal
side, as in Ammonites. The animal occupies the outer chamber,
as in fig. 168.
156
ANIMAL KINGDOM.
The mouth of the Cephalopods has generally a pair of horny
mandibles, like the beak of a hawk in form; and these fossil beaks
have been called Rhyncholites.
These chambered shells containing Cephalopods were once ex¬
tremely numerous ; but only half a dozen living species are known,
and these are of the genus Nautilus. Modern Cephalopods are almost
exclusively naked species, having an internal shell, if any. In a few
species, as in the genus Spirida, the internal shell is chambered and
coiled (the coils not touching) ; but in the rest it is straight, and
serves only to stiffen the soft body. In the Cuttle-fish it is spongy-
calcareous. In the Squid, or Calamary,—a more slender animal,
requiring some flexibility for its movements,—it is horny, and is
called the pen (p, fig. 169). In some cases it has a small conical
cavity at the lower end. In the Belemnite, a group of fossil species,
it was stout, cylindrical, and calcareous, with a deep conical cavity,
and on one side the margin was prolonged into a thin blade
(figs. 702, 703).
The Cephalopods are divided into—
(1.) DihranchiatcH, having two gills or branchiae, as in the Octopus, Cuttle-fish,
Squid, Belemnite, Spirula, Argonaut,—including, therefore, all existing naked
Cephalopods, besides the Argonaut (the Paper-nautilus), whose shell is peculiar
in not being chambered.
(2.) Tetrubrunchiatp.fi, having/our gills, as the name implies; as in the Nautilus
and the chambered shells of ancient time. The Orthoceras (figs. 257, 313, 314)
was a straight form with plane septa or partitions : the name is from the Greek
for strair/lit horn. The Nautilus is a coiled form with plane partitions, and the
siphuncle central or subventral. The Ammonite group (figs. 700, 701, 765, 766)
contains coiled straight forms with the partitions plaited or zigzag (fig. 765 h)
at the margin, and a dorsal siphuncle.
2. Cephalates.—Tlie Cephalates are divided into two groups :—
(1.) The Gasteropods, the group containing the Univalve shells, as
well as some related species without shells,—the animals of which
crawl on a flat spreading fleshy piece called the foot (fig. 166); and
hence the name, from the Greek, implying that they use the venter
or under surface for a foot.
(2.) The Pteropods, which swim by means of wing-like appendages
to the head (fig. 167),—to which the name refers, meaning wing-
footed.
The Gasteropods, which embrace nearly all the cephalate Mollusks, have usually
a spiral shell, as in the common Snail, Buccinum, Turbo, etc. The mantle
of the animal is sometimes prolonged into a tube or siphon in front, to convey
water to the gills ; and in this case the shell has a canal at the beak for the pass¬
age of the siphon. The modern marine univalves without a beak, the Natica
MOLLUSKS.
157
group excepted, are herbivorous, while those having a beak are as generally
carnivorous.
3. Acephals, or Headless Mollusks.—There is but one group,
the Conchifers or ordinary Bivalves, also called Lamellibranchiates.—
These common species are well known as bivalves. Between the
mantle or pallium and the body of the animal lie the lamellar
branchiae, or gills, as is obvious in an oyster; and hence the name
Lamellibranchiates. In a shell like fig. 163, the mouth of the animal
faces almost always (except in some species of Nucula and Solemya)
the margin a, or the side of the shorter slope ; and a is therefore the
anterior side, b the posterior; and, placing the animal with the short
slope in front, one valve is the right, and the other the left. The
hinge is at the back of the Mollusk.
Oil the lower margin of the animal, towards the front part, there is in the
Clam and many other species a tough portion which is called the foot: it is
used, when large, for locomotion, as in the fresh-water Clam; when small, it
sometimes gives origin to the byssus by which shells like the Mussel are
attached. It is wanting, or nearly so, in the Oyster.
The mantle is sometimes free at the lower margin, as in the Oyster ; some¬
times the edges of the two sides are united, making a cavity about the body
open at the ends; in other cases this cavity is prolonged into a tube or siphon,
or into two tubes projecting behind, one receiving water for the gills and the
other giving the water exit. The shell is closed b_y one muscle in the Oyster,
etc., by two in the Clam, etc. The species with two muscles are called Dimyci-
ries,—from the Greek for two muscles ; and those with one, Monomyarics,—from
the Greek for one muscle.
These different peculiarities of the animal are partly marked on the shell. In
figs. 163, 164, the two muscular impressions are seen at 1 and 2; the impression
of the margin of the mantle (pnllial impression, as it is called) at p pi; and in
fig. 164 the siphon is indicated by a deep sinus in the pallia! impression at s.
In 165, the shell of an oyster, there is only one muscular impression. It is
observed also that in fig. 163 about one-tliird of the animal would be anterior
to a vertical line (m) let fall from the hinge; whereas in the Oyster, Avicula,
Mytilus, and related species, the animal is almost wholly posterior to this line;
in other words, the Oyster is all venter, while the Clam is a higher type in the
order of Acephals.
The remaining Mollusks are of a distinct type, namely:—•
The Antiioid Mollusks, many having stems like flowers.
1. Brachiopods.—The Brachiopods (figs. 160, 161, and 216 to
227) have a bivalve shell, and in this respect are like ordinary
bivalves. But the mouth of the animal faces the middle of the lowa-
margin (a) ; and the shell, instead of covering the right and left
sides, covers the dorsal and ventral sides, or its plane is at right
angles to that of a clam. Moreover, the shell of a Brachiopod is
158
ANIMAL KINGDOM.
symmetrical inform, and equal either side of a vertical line a h. The valves,
moreover, are almost always unequal; the larger is the ventral, and the
other the dorsal. There is often an aperture at the beak (near h,
fig. 1G0) which gives exit to a pedicel by means of which the animal
fixes itself to some support. In fig. 161, representing a species of
the genus Lingula, the fleshy support is a long one, and the shell
stands like a plant, with the opening upward.
These Brachiopods are also peculiar in other points of structure.
They have a pallium, but no independent branchial leaflets. They
have a pair of coiled and fringed arms, which they sometimes ex¬
trude (fig. 216),—whence the name Brachiopod, meaning arm-like
foot. For the support of these arms there are often bony processes
in the interior of the shell, of diverse forms in different genera
(figs. 208, 212, and 215).
2. Ascidians, or Tunicates.—These Mollusks are enclosed in a
leathery skin instead of a shell. They do not occur fossil.
3. Bryozoans.—Bryozoans, or moss-animals (so named from the
moss-like corals they often form), look like polyps, as represented
in figs. 162, 162 a. 162 is magnified about eight times. The corals
consist of minute cells, either in branched, reticulated, or incrust-
ing forms, and are common in the Silurian as well as later rocks
and in existing seas. Fig. 162 a represents the animal, showing its
stomach at s, and the flexure in the alimentary canal, with its ter¬
mination alongside of the mouth. Eschara, Flustra, Retepora, are
names of some of the genera.
IV. Radiates.
The sub-kingdom of Radiates contains three classes:—
1. Eciiinoderms.—Having the exterior more or less calcareous,
and often furnished with spines and distinct nervous and respira¬
tory systems and intestine, as the Echinus (fig. 153), Star-fish (fig.
154), Crinoid (fig. 155). The name is from echinus, a hedgehog, in allu¬
sion to the spines.
2. Acalephs.—Having the body usually nearly transparent or
translucent, looking jelly-like. Internally a stomach-cavity, with
radiating branches ; also a circular nervous cord. Ex., the Me¬
dusa, or Jelly-fish (fig. 150). They generally float free, with the
mouth downward.
3. Polyps.—Fleshy animals, like a flower in form, having above,
as seen in figs. 147,148, a disk with a mouth at centre and a margin
of tentacles ; internally, a radiated arrangement of fleshy plates ;
and living for the most part attached by the base to some support.
Ex., the Actinia, or Sea-Anemone, and the Coral animals.
RADIATES.
159
All these classes commence in the Lower Silurian; and some of
their subdivisions are therefore here mentioned.
1. Echinoderms. — The subdivisions of Echinoderms are as
follow:—-
1. Holothurioids.—Having the exterior soft, and throughout ex¬
tensile or contractile, and the body stout, subvermiform in shape.
The group is not known among fossils. It includes the Biche de
mar, or Sea-slug.
2. Echinoids.—Having a thin and firm hollow shell, covered ex¬
ternally with spines (fig. 153); form, flattened spheroidal to disk-
shape; the mouth below, at, or near the centre, as the Echinus,
fig. 153.
3. Asterioids. — Having the exterior stiffened with calcareous
pieces, but still flexible; form, star-shaped and polygonal; mouth
below, at centre; animal free, except in the young state. Ex., the
Star-fish, fig. 154.
4. Crinoids.—Crinoids are related to the Asterioids and Echi¬
noids, but have, with few exceptions, a permanent stem or
pedicel, as figs. 155, 156, 158. They are thus like the young Aste¬
rioids. The stem is attached to the back, and they stand with
the mouth upward. Fig. 155 represents the Crinoid closed, like
a closed bud; when opened, it would appear like an opened
flower, and each ray would be seen to be delicately fringed, as
in fig. 158.
A. Echinoids.—Fig. 153 represents an echinus partly uncovered
of its spines, showing the shell beneath, and 157 another, wholly
uncovered. The shell consists of polygonal pieces in twenty ver¬
tical series arranged in ten pairs. Five of these ten pairs are per¬
forated with minute holes, and are called the ambulacral series (a
in fig. 153 represents one pair); and the other five alternating with
these are called the intcr-ambidacral (b). The inter-ambulacral
areas have the surface covered with tubercles, and the tubercles
bear the spines, which are all movable by means of muscles. The
ambulacral have few smaller tubercles and spines, or none; but
over each jaore (or rather each pair of pores) the animal extends
out a slender fleshy tentacle or feeler, which has sometimes a
sucker-like termination and is used for clinging or for loco¬
motion. The ambulacral areas are thus distinguished from the
others by being generally much narrower, by having smaller
spines or none, and by having a multitude of these tentacles
or feelers,—the use of which is partly for aiding the animal in
its motions, partly for seizing food, and partly to supply vesicles
in the interior with water for the purposes of respiration. In
160
ANIMAL KINGDOM.
fig. 157 the inter-ambulacral areas are broad and the plates large,
but the ambulacral are narrow and the plates indistinct.
The month-opening is situated below at the centre of radiation of the plates.
The anal opening in the Regular Echinoids (fig. 153) is at the opposite or
dorsal centre of radiation. Around the anal opening there are five minute ova¬
rian openings.
In the Irregular Echinoids—constituting a large group—the anal opening is
to one side of this dorsal centre of radiation, and often on the ventral or under
surface of the animal. In fig. 157, for example, the anal opening is marginal
instead of central, while the ovarian pores are at the dorsal centre, as in the
Regular Echinoids.
To one side of the dorsal centre (to the right of the front side), in the Regu¬
lar Echinoids, there is a small porous prominence on the shell, often called the
madreporic body, from a degree of resemblance in structure to coral. In the
Irregular Echinoids this madreporic body is in the centre of dorsal radiation.
The ambulacral areas are sometimes perforated through their whole length.
But in other cases only a dorsal portion is perforated, as in fig. 157, and, as this
portion has in this case some resemblance to the petals of a flower, the ambu¬
lacra are then said to be pietaloid. A large part of the Echinoids have a circle of
five strong, calcareous jaws in the mouth; in another portion there are no jaws.
The Echinoids have been divided into—
I. Regular Echinoids.
1. Gidaris Family.—Having the inter-ambulacral spaces consisting of two
series,—the general fact in Echinoids, as above stated.
2. The Archeeocidaris Family, having the inter-ambulacral spaces consisting
of more than two series of plates —a peculiarity confined to the Palmozoic
Echinoids.
II. Irregular Echinoids.
1. Galerites Family.—Mouth-opening central, furnished with jaws; ambula¬
cral area perforate throughout. (Found only fossil.)
2. Clypeaster Family.— Like the preceding, but ambulacra petaloid. (Fossil
and recent.)
3. Echinoneus Family.—Like the Galerites family, but no jaws. (Recent.)
4. Cassidulus Family.—Like the Clypeaster family, but no jaws. (Fossil
and recent.)
5. Spatangus Family.—Mouth-opening not central, and having a bilabial
form instead of round or stellate; ambulacra petaloid ; no jaws. (Fossil and
recent.)
6. Dysaster Family.—Ambulacral areas not radiating from a common area on
the back, but two dorsally distant from the others. Whether there were jaws or
not is undetermined. (Fossil.)
B. Asterioids.—The Asterioids (Star-fishes) have the mouth below:
and there are ambulacral pores and sucker-feelers along the middle
of the under surface of the rays. The groups are,—
1. Asterias Family (Asteridce).—Rays broad; viscera extending into
the rays.
RADIATES.
161
2. Ophiura Family (Ophiuridm).—Kays slender and very flexible;
viscera confined to the central disk of the Star-fish, as in Ophiura.
3. Comatula Family (Comatulidce).—Rays narrow, often much sub¬
divided ; a small supplementary series of arms on the back for
clinging; and the animal usually attached by these dorsal arms
so as to have the mouth upward, unlike other Asterioids, as in the
genus Comatula.
C. Crinoids.—There are two tribes:—
1. The Crinidea or Encrinites.—Having a regular radiate structure,
and the arms proceeding from the margin of the disk, as in figs.
155 and 158.
2. Cystidea (from the Greek for a bladder), fig. 156. Radiate
arrangement of the plates not distinct. Arms when present pro¬
ceeding from the centre of the summit instead of the margin of a
disk; in some only two arms ; often wanting, and replaced by
radiating ambulacra! channels, which are sometimes fringed with
pinnules.
The Crinids closely resemble a Comatula; only they have a stem,
instead of the short arms, for attachment. The stem consists of calca¬
reous disks like button-moulds in form, set in a pile together, and
hence in the living animal it has some flexibility. Fig. 158 repre¬
sents a modern Crinid (Pentacrinus Caput-Medusa) from the West
Indies. The mouth is at the centre between the arms. Fig. 155 c
represents the form of one of the disks of the stem in an extinct
Crin(d. The disks in Palaeozoic species are generally round or
oval; and they were the same also in many later species. Penta¬
gonal disks commence in the Lower Silurian, and are most common
in the Mesozoic formations. The pentagonal forms represented
in fig. 158, a, b, c, d, pertain to the Pentacrinus family, the only
family of Crinids now known to exist.
In ancient Crinids or Encrinites, the arms are not free down to
the pedicel, but there is a union of their lower part, either directly
or by means of intermediate plates, into a cup-sliaped body or calyx
(as in fig. 155, and also figs. 527, 528, under the Carboniferous age).
In fig. 159, the plates of one of these cups in the species Actinocrinus lonyi-
rostris H. are spread out, the bottom plates of the cup being at the centre.
The plates, it is seen, are in five radiating series, corresponding to the five rays
or arms of the Crinid, and between are intermediate pieces. The three plates
numbered 1 are called the basal, as the stem is articulated to the piece composed
of them; 3, 3, 3 are the radial; 4, 4, supra-radial; 5. brachial, situated at the
base of the arms; 7 are intermediate plates, called inter-radial; 8, another inter¬
mediate, the inter-supraradial. Sometimes, in other Crinids, there is another
series of plates, at the junction of the plates 1 and 3, called sub-radials. Finally,
12
162
ANIMAL KINGDOM.
the anal opening of a Crinid is situated on one side of the body, it being lateral,
as in the Echinoid in fig. 157; and the intermediate group of plates numbered
10 are called the anal.
Nearly all the Palaeozoic Crinoids have the anal and oral apertures together,
there being but a single opening in the summit (Cyathocrinus is said to be an
exception). This opening is sub-central (fig. 524) or lateral (fig. 525), and
in the former cases is often (as in many species of Actinocrinus) situated at the
summit of a slender proboscis made up of small pieces and sometimes three or
four times as long as the body. In some species of Poteriocrinus (P. Jlis-
souriensis Shumard = P. longidactyhm, Shumd. Mo. Rept., p. 188) the pro¬
boscis is very large, being nearly as wide as the body and four or five times
as long. It is composed of regular ranges of hexagonal plates, with a series
of pores between every alternate range, much like the ambulacral pores in the
true Echinoids.
In the Cystids the aperture is generally lateral and remote from the top, as
in fig. 156, while the arms come out often from the very centre.
The Cystids are also peculiar in what are called pectinated rhombs (see fig.
156); that is, rhombic areas crossed by fine bars and openings: the use of them
is uncertain,—though they are probably connected with an aquiferous system
and respiration. The Cystids are the most anomalous of Radiates.
Among the Crfnidea there are—first, the species with arms and rounded stems,
which are of several genera and families. Second, the Pentacrinus group, which
also have long arms, but the stems are five-sided. Third, the Blastoids, which
have round stems, but the body is pentagonal and flower-like or petaloid in its
divisions, and the divisions are furnished with pinnules: Ex., the Pentremites.
As they are usually found closed up, they have a resemblance to a flower-bud;
and hence the name, from the Greek.
2. Acalephs.—Besides the jelly-like Acalephs, which have very
rarely left any traces in the strata, there are delicate coral-making
species - of the Hydroid group. Fig. 151 represents a Hydra,
much enlarged; 152, a related animal of the Tuhularia family
(genus Syncoryna). Other species, having animals like 151, as in
the genera Campantdaria and Sertularia, form very delicate mem¬
branous coralla, which under the microscope consist of series
of minute cells ; and the fossils called Graptolites have been com¬
pared to them. The hard, stony corals called Millepores have
been shown by Agassiz to have animals like fig. 152, and there¬
fore to belong to the class of Acalephs. The genera of fossil
corals Chcetetrs and Fucosilcs, having the cells divided by horizontal
partitions, and being in this respect like Millepores, he refers to
the same group.
There are, hence, not only stony corals made by Polyps, as in the
common kinds, but there are also large stony corals made by Aca¬
lephs, besides delicate kinds which were made either by Hydroid
Acalephs or Bryozoan Mollusks.
PROTOZOANS.
1G3
3. Polyps.—There are two groups of Polyps:—
1. Actinoid Polyps, illustrated in figs. 147, 148, and all ordinary
corals. The rays of the polyps are of variable number, and naked
(not fringed).
The coral is secreted within the polyps, as other animals secrete
their bones. It is internal, and not external. It is usually covered with
radiate cells, each of which corresponds to a separate polyp in the
group. The rays of a cell correspond to fleshy partitions in the
interior of the polyp, and the cavity of a cell is the space occupied
by the stomach and visceral cavity: it is not, therefore, a cavity
into which the polyp retreats; it is the inside of the polyp itself.
The material is carbonate of lime (limestone) ; and it is taken
by the polyp from the water in which it lives, or from the food
it eats.
2. Alcyoxoid Polyps, illustrated in fig. 149, and the Gorgonia
and Alcyonium corals. The rays of the polyps are eight in number,
and fringed. The figure represents a part of a branch of a Gor¬
gonia (Sea-Fan), with one of the polyps expanded. The branch
consists of a black horny axis and a fragile crust. The crust is partly
calcareous, and consists of the united polyps ; the axis of horn is
secreted by the inner surface of the crust. The Precious Coral used
in jewelry comes from the shores of Sicily and Southern Italy, and
belongs to this Alcyonoid division. It is related to the Gorgonias,
but the axis is red and stony (calcareous) instead of being horny,
and this stony axis is the coral so highly esteemed.
Among the Actinoid Polyps there are the following groups,—ex¬
clusive of those that do not secrete coral:—
1. The Actinia tribe.—The number of rays a multiple of six. It includes the
Astra?a family, Oculina family, Fungia family, Caryophyllia family, Madre-
pora family, Pontes family.
2. The Cyathojihyllum tribe.—The number of rays a multiple of four. It
contains only Palteozoic corals, replacing in that era the Astrmoid corals of later
eras. The animals were probably like the Actinia in fig. 147.
V. Protozoans.
The groups of Protozoans of special interest to the geologist are
two:—
1. Rhizopods, or Foraminifers. — Species mostly microscopic,
forming calcareous shells. These shells, with few exceptions,
are very minute,—many times smaller than the head of a pin ;
and yet they have contributed largely to the formation of lime¬
stone strata. They consist of one or more cells; and the com-
164 ANIMAL KINGDOM.
pound kinds present various fanciful shapes, as illustrated in the
annexed cut.
Figs. ISO to 193.—Rhizopods, much enlarged (excepting 192, 193). Fig. ISO, Orbuliua
universa; 181, Globigerina rubra; 182, Textilaria globulosa Ehr.; 183, Rotalia globulosa;
183 a, Side-view of Rotalia Boucana; 1S4, Grammostomum phyllodes Ehr.; 1S5, a, Fron-
dicularia annularis; 1S6, Triloculina Josephina; 1ST, Nodosaria vulgaris: 1SS. Lituola
nautiloides; 189, a, Flabellina rugosa; 190, Chrysalidina gradata; 191, a, Cuneolina pavo-
nia; 192, Nummulites nummularia; 193 a, h, Fusulina cylindrica. All but the last two
magnified 10 to 20 times.
Fig. 180 is a one-celled species; the others are compound, and contain a num¬
ber of exceedingly minute cells. A few are comparatively large species, and
have the shape of a disk or coin, as fig. 192, a Xunimulite, natural size; the figure
shows the interior cells of one-half: these cells form a coil about the centre.
Orbitoides is the name of another genus of coin-like species. Fig. 193 a is a
species of Fusulina, a kind nearly as large as a grain of wheat, related to the
Nummulites ; 193 b is a transverse view of the same. This is one of the ancient
forms of Rhizopods, occurring in the rocks of the Coal formation.
D'Orbigny divided the Rhizopods into (1) the one-celled (called Jlonostegse by
D'Orbigny); (2) shells having the segments in direct linear series, figs. 185,
187 (Stichosteyse); (3) shells spiral, the spiral of a single series, figs. 181. 182.
183, 184, 188, 189, 190, 192, 193 (Helicostegse); (4) shells spiral, consisting of
alternating segments, genus Robertina, etc. (Entomostegx): (5) shells consisting
of alternating segments not spirally arranged, fig. 191 (Enallostcgie); (6) seg¬
ments clustered, without linear or spiral order, about an axis, fig. 186 (Ayatho-
stegm). (See Appendix A.)
The cells of Rhizopods are each occupied by a separate animal or
zooid, though each is organically connected with the others of the
same group or shell. The animal is of the simplest possible kind,
having no mouth or stomach or members. It projects at will
slender processes of its own substance through pores in the shell.
The above are shell-making species of Rhizopods. The name Rhizopods comes
from the Greek for root-like feet,—in allusion to the root-like processes they
SPONGES.
165
throw out. The shell-making species have been distinguished as Foramimfers,
from the pores above alluded to. Some of the species not secreting shells (as in
the genus Amoeba) have been seen to extemporize a mouth and stomach. When
a particle of food touches the surface, the part begins to be depressed, and
finally the sides of the depression close over the particle, and thus mouth and
stomach are made when needed; after digestion is complete, the refuse portion
is allowed to escape.
The shells of some Ehizopods do not consist of distinct cells : the aggregate
living mass secrete carbonate of lime, without retaining the distinction of the
zooids. This is the case, as Carpenter has observed, in the Nummulite-like
genus Orbitolitcs.
2. Sponges.—Sponges are regarded as compound animals, con¬
sisting of an aggregate of zooids related to those of the Ehizopods.
The cylindrical water-passages serve to supply water for respiration,
and also such food as the water may contain. The material of the
Sponge is a little like horn in its nature ; its microscopic characters
show that it is not vegetable. Besides the general tissue of the
Sponge, there are in most species microscopic spicula through the
tissues, which are siliceous (figs. 194, a-h),—some of them acicular,
others with divergent rays. They are in great numbers in some
species; and even the fibres of the Sponge are sometimes siliceous.
In some few species the spicula are calcareous.
There are other siliceous microscopic organisms, called Polycys-
tines and Diatoms. The latter are vegetable in nature, and are men¬
tioned on p. 167. For a notice of the former, see p. 748.
2. VEGETABLE KINGDOM.
The vegetable kingdom is not divisible into sub-kingdoms like •
the animal; for the species all belong to one grand type, the Ra¬
diate, the one which is the lowest of those in the animal kingdom.
The higher subdivisions are as follow:—
I. Cryptogams.—Having no distinct flowers or proper fruit, the
so-called seed being only a spore, that is, a simple cellule without
the store of nutriment (albumen and starch) around it which makes
up a true seed ; as the Ferns, Sea-weed. They include—
1. Thallogens.—Consisting wholly of cellular tissue; growing in
fronds without stems, and in other spreading forms; as (1) Algae, or
Sea-weeds; (2) Lichens.
Fig. 194.
Siliceous spicula of Sponges.
166
VEGETABLE KINGDOM.
2. Anogens.—Consisting wholly of cellular tissue; growing up in
short, leafy stems; as (1) Musci, or Mosses; (2) Liverworts.
3. Acrogens.—Consisting of vascular tissue in part, and growing
upward; as (1) Ferns; (2) Lycopodia (Ground-Pine); (3) Equiseta;
and including many genera of trees of the Coal period.
II. PmENOGAMS.—Having (as the name implies) distinct flowers
and seed; as the Pines, Maple, and all our shade and fruit trees,
and the plants of our gardens. They are divided into—
1. Gymnosperms.—Having the flowers exceedingly simple, and the
seed naked,—the seed being ordinarily on the inner surface of the
scales of cones; growth exogenous, the trees having a bark and
rings of annual growth (fig. 195); as the Pine, Spruce, Hemlock, etc.
The name gymnosperm is from the Greek for naked seed. Gymnosperms
include (1) Conifers; (2) Cycads (p. 418); and (3) Sigillarids (p. 335).
Figs. 195-204.
Piants.—Tig. 195, section of exogenous wood; 196, fibres of ordinary coniferous wood (Pinu*
Strobus), longitudinal section, showing dots, magnified 300 times; 197, same of the Austra¬
lian Conifer, Araucaria Cunninghami; 198, section of endogenous stem.
Figs. 199 to 204, Diatoms highly magnified; 199, Pinnularia peregrina, Richmond, Va.; 200,
Pleurosigma angulatum, id; 201, Actinopticus sonarius, id; 202, Melosira sulcata, id; a,
transverse section of the same; 203, Gramuiatopliora marina, from the salt water at Ston-
ington, Conn.; 204, Bacillaria paradoxa, West Point.
The wood of the Conifers is simply woody fibre without ducts,
and in this respect, as well as in the flowers and seed, this tribe,
shows its inferiority to the following subdivision. The fibre, more¬
over, may be distinguished, even in petrified specimens, by the dots
along their surface as seen under a high magnifier. The dots look
like holes, though really only thinner spaces. Fig. 196 shows these
dots in the Pinus Strobus. In other species they are less crowded.
Tn one division of the Conifers, called the Araucaria; of much geo¬
logical interest, these dots on a fibre are alternated (fig. 197); and
the Araucarian Conifers may thus be distinguished.
2. Angiosperms.—Having regular flowers and covered seed; growth
exogenous, the plants having a bark and rings of annual growth
(fig. 195); as the Maple, Elm, Apple, Rose, and most of the ordinary
SILURIAN AGE.
167
shrubs and trees. These Exogens are called Angiosperms, because
the seeds are in seed-vessels; and also Dicotyledons, because the seed
has two cotyledons or lobes.
3. Endogens.—Regular flowers and seed; growth endogenous, the
plants having no bark, and showing in a transverse section of a
trunk the ends of fibres, and no rings of growth (fig. 198) ; as the
Palms, Rattan, Reed, Grasses, Indian Corn, Lily. The Endogens
are Monocotyledons; that is, the seed is undivided, or consists of but
one cotyledon.
Only the salt-water species of plants—Algse, or Sea-weeds—are
known to occur in the Silurian. Among the fossil Algse there are
two prominent kinds :—
1. Fucoicls.—Related to the tough, leathery sea-weeds of sea-coasts,
which are called Fuci, and which grow in great profusion in some
seas, attaining a length at times of several rods.
2. Protophytes, or microscopic species.—Mostly unicellular plants.
The Diatoms secrete a siliceous shell; and they grow so abundantly
in some waters, fresh or salt, as to produce large siliceous accumula¬
tions. A few of these siliceous species are figured above, in figs.
199 to 204.
The Desmids do not secrete siliceous shells. They consist of one
or a few greenish cells. (See figs. 441 A, a to g, p. 271.)
II. PALAEOZOIC TIME.
I. AGE OF MOLLUSKS, OR SILURIAN AGE.
The term Silurian was first applied to the rocks of the Silurian
age by Murchison, and is derived from the ancient name Silures,
the designation of a tribe inhabiting a portion of England and
Wales where the rocks abound. The rocks occur on all the
continents and over much of their surface, constituting strata of
sandstone, shale, conglomerate, and limestone; and the most
of the strata abound in fossils, as shells, corals, and other allied
forms.
The subdivisions of the Silurian are not only widely different on
the two continents, America and Europe, but also on different
parts of the same continent. In American geological history it has
been found most convenient to recognize that subdivision into
periods and epochs which is derived from the succession of rocks
168
PALAEOZOIC TIME SILURIAN AGE.
in the State of New York, where the strata are well displayed and
have been carefully studied.
Some standard for our divisions of time must be adopted; and, whatever that
standard, it is afterwards easy to compare with it, and bring into parallelism,
the successive strata or events of other regions. The State of New York lies on
the northeastern border of the great interior,—a vast region stretching south¬
ward and westward from the Appalachians to the Rocky Mountains, and
beyond the head-waters of the Mississippi to the Arctic Ocean, over which
there were many common changes; and, owing apparently to this situation
on the north against the Azoic, and near the head of the Appalachian range,
there are indicated a greater number of subordinate subdivisions in the rocks,
or of epochs in time, than are recognized to the west. It is, therefore, a more
detailed indicator of the great series of changes and epochs in the Palaeozoic
era, and hence it is especially well fitted to become the basis of a scale or
standard for the subdivision of time. This will be apparent in the course of the
following pages.
The order of succession in the Silurian periods and rocks is
shown in the section on page 131 (fig. 134). The numbers affixed
to the subdivisions of the section are used for the same formations
throughout the work.
Subdivisions of the Silurian.
II. UPPER SILURIAN.
3. Lower Helderberg Period (7).
Lower Helderberg limestones, including in New York (1)
the Water-lime group; (2) the Lower Pentamerus limestone;
(3) the Delthyris shaly limestone; (4) the Upper Pentamerus
limestone.
In Great Britain, the Ludlow beds, including the Lower Ludlow limestone,
the Aymestry limestone, Upper Ludlow limestone. In Norway, Upper Malmd
limestones and schists.
2. Salina Period. (6.)
Onondaga Salt group.
1. Niagara Period (5).
4. Niagara Epoch (5 d): Niagara shale and limestone.
3. Clinton Epoch (5 c): Clinton group.
2. Medina Epoch (5 b): Medina sandstone.
1. Oneida Epoch (5 a): Oneida conglomerate.
In Great Britain the Wenlock shale and limestone are referred to the Niagara
(5 d); the Upper Llandovery, to the Clinton (5 c); and the Upper Caradoc sand¬
stone, Coniston grits, Lower Llandovery, to the Medina and Oneida epochs (5 b
and 5 a). Murchison divides the Upper from the Lower Silurian of Britain at
SILURIAN AGE.
169
the bottom of the Upper Llandovery; the Upper Llandovery is thus made Upper
Silurian, and the lower, Lower Silurian.
In Bohemia, Barrande's formations E to H are referred to the Upper Silurian,
consisting of schists, part Graptolitic, and limestones. In Norway, Encrinal
schists, Coral and Pentamerous limestone, Lower Argillaceous schists.
I. LOWER SILURIAN.
3. Hudson Period (4).
2. Hudson Epoch: Hudson River shale (45).
1. Utica Epoch: Utica shale (4a).
In Great Britain, Lower Caradoc sandstone, and upper part of Llandeilo
flags. In Bohemia, part of Barrande's formation D. In Sweden, Orthoceratitc
limestone and Encrinal schists, flagstone. Angelin's Region D.
2. Trenton Period (3).
2. Trenton Epoch (3 5): Birdseye limestone (3 5'), Black
River limestone {3 b"), Trenton limestone (3 b"').
1. Chazy Epoch (3 a): Chazy limestone.
In Great Britain, Bala limestone and Llandeilo flags. In Bohemia, Bar¬
rande's formation D. In Sweden, Angelin's C, Orthoceratite limestone. In
Russia, schists and Orthoceratite limestone, called the Pleta; Ungulite grit of
Pander beneath the limestone.
1. Potsdam, or Primordial Period (2).
2. Calciferous Epoch (2 5): Calciferous sanclrock in New
York. Sandstone with very thick shales and some limestone
forming the larger part of the " Quebec" group of Canada and
the Taconic of Emmons. Magnesian limestone of the Missis¬
sippi valley. Sandstones ancl Magnesian limestone in Eastern
Tennessee.
1. Potsdam Sandstone (2 a): Potsdam sandstone in New
York, and sandstone with some limestone in the West. Thick
slates, sandstone, and some limestone in and along the Green
Mountains and the Alleghanies. Chilhowee sandstones, Ten¬
nessee.
In Great Britain, Lingula flags ; hard sandstones with schists below at Stiper
Stones in Shropshire; Black schists at Malvern; Tremadoc slates; Skiddaw
slate. In Bohemia, Barrande's Primordial Zone, C. In Norway and Sweden,
Angelin's A and B, Fucoidal sandstone and millstone, Olenus beds, schists.
Explanation of the Geological Map.
The annexed map of New York and a part of Canada exhibits
the surface-rocks of the region. As remarked under the Azoic
Geological Map of New York and Canada.
POTSDAM PERIOD.
171
(p. 137), the strata of the Silurian and Devonian outcrop in suc¬
cession on going from the Azoic (Xo. 1) southward. The numbers
on the areas render a comparison with the section and with the
tables beyond easy. The Silurian strata are lined horizontally; the
Devonian, vertically; and the subcarboniferous beds, which appear
at the southern margin of New York State (Xo. 13) are cross-lined.
The area 2, which is that of the Potsdam period, is divided into two portions,
one distinguished as a or 2 a, and the other as b or 2 b: the former is the area
of the rocks of the Potsdam epoch, and the latter of the Calciferous epoch, which
epochs are elsewhere in the work distinguished by the same numbering. Other
areas are similarly divided. As another example, the area 5 (Niagara period) is
divided into a, b, c, d, corresponding to 5 a, 5 b, 5 c, 5 d in the above table. The
areas of Nos. 7 and 8 in the series (the Lower Helderberg closing the Silurian,
and the first period of the Devonian) are not distinguished on the map from
No. 9.
Fig. 206 is an ideal section of the rocks of New York, along a
line running southwestward from the Azoic on the north across the
Fig. 206.
Carboni- Devonian. Silurian,
ferous.
State to Pennsylvania. It shows the relative positions of the suc¬
cessive strata,—bringing out to view the fact that the areas on the
map are only the outcrops of the successive formations. This is all
the section is intended to teach : for the uniformity of dip arid its
amount are very much exaggerated, and the relative thickness is
disregarded.
A.—LOWER SILURIAN.
1. POTSDAM OR PRIMORDIAL PERIOD (2).
Epochs.—1. The Potsdam epoch, or that of the Potsdam sand¬
stone (2 a). 2. The Calciferous epoch, or that of the Calciferous
sandrock (2 b).
172
PALAEOZOIC TIME—LOWER SILURIAN.
I. Rocks : kinds and distribution.
1. American.
The Potsdam formation (numbered 2 on the map, p. 170) ap¬
pears at the surface just south of and adjoining the Azoic areas in
New York and the West; the strata here exposed are the outcrop¬
ping portions of a formation that probably underlies all the fossili-
ferous rocks of the great Mississippi valley, and stretches south
beyond Texas, and north, either side of the Azoic axis of the con¬
tinent, into the Arctic regions. These Primordial strata have been
observed and studied in Texas, about the Black Hills of Dakota
and the Laramie Range of the Rocky Mountains, and north in British
America. They are also surface-rocks at various places along the
Appalachian chain from the St. Lawrence through western Ver¬
mont to Alabama and Tennessee. East of this chain, they occur
near Boston at Braintree, in Newfoundland, and in Labrador.
These strata have hence a wide continental range, a universality
of distribution unexceeded among later formations.
The rock of the Potsdam epoch is mostly a laminated sandstone
in New York. Along the northern border of the United States, and
south, over the Mississippi basin, there is, in addition, some lime¬
stone ; and a vast .thickness of slate or shale exists along the Appa¬
lachians from the St. Lawrence southwestward.
The Calcif'erous epoch, as the name implies, was characterized to
a considerable extent by limestone-making, though less strikingly
so than the epochs of the Trenton period, which next succeed.
The rock is a hard sandstone, more or less calcareous, in New York ;
a magnesian limestone, with some sandstone, in the Mississippi
basin, where it is often called the Lower Magnesian limestone; sand¬
stone with very thick shales, and some beds of limestone, along the
course of the Appalachians, north and south.
The thickness of the beds of the Potsdam period in New York,
Western Canada, and the Mississippi basin, varies usually from 30
to GOO feet; but along the Appalachians the rocks have an enor¬
mous development, being from 2000 to 7000 feet thick.
The rocks of the Potsdam period in many places overlie horizon¬
tally or nearly so the crystalline Azoic, as illustrated in figs. 136,
137, 138. In 136 the Potsdam sandstone (2 a) and Calciferous
sandrock (2 b) rest upon the folded Azoic of Essex co., N.Y.; and
in 138, from Canada, there is the same condition, with also the
Trenton limestone (3) and Utica shale (4w) overlying the Potsdam
strata. The following cut, from a sketch by J. D. Whitney, represents
POTSDAM PERIOD.
173
the juxtaposition of the Potsdam and Azoic near Carp River, south
of Lake Superior; the former rock (on the right in the view),
slightly inclined sandstone ; the latter (on the left), quartzite in
Fig. 207.
a nearly vertical position, which position it had received before
the deposition of the sandstone.
Through New York and the greater part of the Mississippi basin
the strata have usually a gentle dip or are nearly horizontal. Along
the Appalachian chain, east of Lake Champlain and the Hudson,
in the region of New England, of the Alleghanies in Pennsylvania,
and of the Cumberland Mountains in Tennessee, they are up¬
turned at all angles to verticality.
1. Potsdam epoch.—a. Interior Continental basin.—The Potsdam sand¬
stone in New York varies from a hard quartzite, as at Keeseville, N.Y., and
Adams, Mass., to a friable sandstone. Much of it is a good building-stone,
as at Potsdam, Malone, and elsewhere, N.Y. The colors are gray, drab,
yellowish, brownish, and red. In the West, in Michigan, Wisconsin, and
Minnesota, the rock is often so soft as to crumble in the fingers. This want
of firmness in one of the most ancient of rocks shows how ineffectual are ordi¬
nary waters, even through the lapse of ages, in causing solidification. At some
localities it consists of a clean white sand and crumbles readily, making a
good material for glass. The rock is sometimes a conglomerate, especially
in its lower part, for ten or twelve feet; on the north side of the Azoic in the
northwest part of Clinton co. and part of St. Lawrence co., near De Kalb,
174
PALAEOZOIC TIME—LOWER SILURIAN.
and also in Franklin co., N.Y., the conglomerate attains in places a thickness
of 300 feet.
On the south shores of Lake Superior, east of Grand Island, the Potsdam
epoch is represented by the famous " Pictured" rocks, which form bluffs of 50
to 200 feet on the south shores and are variegated in color with vertical bands
and blotches. The color is often a red blotched with light gray, the red being
due to oxyd of iron, and the gray to a removal of the previous red color by
organic matter ; other colors are brown, greenish, and yellowish. Some of the
rock is very soft and fragile, and other parts are hard and gritty. The
" Pillared" rocks near the west end of Lake Superior are of the same age. On
the St. Croix, in Wisconsin, the rock is for the most part a laminated sandstone
of various colors, and either soft or hard. Some portions are partly calca¬
reous; and towards the top of the series true limestone layers are intercalated.
Green-sand like that of the Cludk formation occurs in some of the beds on the
Upper Mississippi. (Hall.)
The Potsdam beds of Texas occur in Burnet co., Texas, where they consist of
sandstones covered by limestone. (B. F. Shumard.)
Beds of sandstone and conglomerate, according to Dr. Hayden, skirt the
Black Hills of Dakota (lat. 43°-45°- N., long. 103°-104° W.), overlying the
Azoic and containing characteristic fossils. Dr. Hayden has also observed a
similar sandstone and conglomerate in the Laramie Range of mountains, along
the margins of the Big Horn Range (lat 43°, long. 107°), and along the Wind
River Mountains. Those of the Big Horn Range afforded the usual Primordial
fossils.
The Potsdam formation is 60 to 70 feet thick in St. Lawrence co., N.Y.,
diminishing in some places to 20 or 30 feet; in Warren and Essex cos., 100 feet;
in the St. Lawrence valley, 300 to 600 feet; about 250 feet in Lake Superior;
700 feet, according to Owen, on the St. Croix, Wisconsin; 50 to 80 feet in the
Black Hills, Dakota; 200 feet at the Big Horn Range; 500 feet in Burnet
co., Texas.
On Lakes Superior and Huron, in the copper region, there is a great thicken¬
ing of the Primordial strata, in connection with eruptions of trap. The rocks
rise in some places to a height of 3000 or 4000 feet, and consist of these igneous
rocks mingled with the sandstone and a scoria conglomerate. These beds are
mostly of the Calciferous epoch. (J. D. Whitney.)
h. Retiion of the Appalachians.—Along the Appalachian chain the great thick¬
ness of the accumulations, and especially of the slates, is the striking peculiarity.
At Highg-ate, near the northern boundary of Vermont, the rock is a red sand¬
stone containing fossils. This sandstone extends north into Canada, occurring
near Herrick's Mills, in the township of St. Armand. It also occurs west of
Swanton, in Vermont, where it is interstratified with black shales which contain
the peculiar fossils of the epoch, and some species are identical, according to
Billings, with those found on the north side of the Straits of Belle Isle. At
Snake and Buck Mountains, in Addison co., Vt., there are 700 feet of black
shale overlaid by a thick bed of sandstone and magnesian limestone, all of the
Potsdam epoch (Billings). At Georgia, Vt., there are black shales which have
afforded some large trilobites. South of these regions, east of the Hudson
River, along by the Taconic Mountains (2", 2" on map, p. 170), in the western
POTSDAM PERIOD.
175
slope of the Green Mountain Range, the Potsdam epoch is supposed to include
the lower shales, while the rest of the rocks may be of the Calciferous epoch.
In Pennsylvania there are 2000 feet of lower slates, overlaid by 90 feet of
sandstone, and this by 200 to 1000 feet of upper slates (H. D. Rogers). In Vir¬
ginia there are 1200 feet of lower slates, 300 of sandstone, and 700 of upper slates
(W.B.Rogers). In eastern Tennessee Professor Safford has described, as of
this age, the " Chilhowee" sandstones and shales, several thousand feet in
thickness (consisting of sandy shales, sandstones, and light gray quartzite),
resting on the Ocoee conglomerates, sandstones, and micaceous, talcose and
chloritic slates.
c. Eastern border.—On the north side of the Straits of Belle Isle, north of
Newfoundland, the Potsdam rocks are gray and reddish sandstone, 231 feet
thick, overlaid by 141 feet of limestone, with some shale, and the latter contains
fossils related to those of Georgia, Vt., while in the former there is the Scoli-
thus of the New York beds.
2. CalciferOUS epoch.—a. Interior Continental basin.—In northern New
York some of the layers of this Calciferous sandrock are very hard and sili¬
ceous, and contain geodes of quartz crystals, as at Diamond Rock, Lake George,
and Middleville and elsewhere in Herkimer co., etc. The impure limestone
layers are adapted for the production of hydraulic lime. The mixture of cal¬
careous with hard siliceous characteristics is a striking peculiarity of the rock.
Owing to the lime present, much of it becomes rough from weathering. Besides
quartz and calcite, barytes, celestine, gypsum, and occasionally blende and
anthracite, are found in its cavities.
In Michigan, south of Lake Superior, the Calciferous beds are arenaceous, as
in New lTork, but with some magnesian limestone. Farther west and south
the "magnesian limestone" of the epooh is an extensive formation; but it con¬
tains some intercalated sandstone, and in its lower layers are occasionally geodes
of quartz or chert. On the Upper Mississippi, at the Falls of St. Anthony, and
also in Iowa, Minnesota, and Wisconsin, the limestone is overlaid by the St.
Peter's sandstone (Owen), a friable, incoherent, white rock, affording sand for
glass-making. (Whitney.)
In Missouri there are—(1) a magnesian limestone (No. 1) overlaid by a sand¬
stone (2), about 350 feet in thickness; (3) a second magnesian limestone, with
some sandstone layers and chert, 500 to 600 feet thick; (4) a sandstone, often
cherty and containing quartz crystals in cavities, 70 feet,- (5) a third magnesian
limestone, cherty and arenaceous, 150 feet; (6) another sandstone; (7) a fourth
magnesian limestone. (Swallow.)
The thickness in Canada is about 150 feet; in New York State, 50 to 300 feet;
in Michigan, on the Menomonee (Lake Superior region), 50 to 100 feet; in Wis¬
consin and Iowa, over 200 feet; in Missouri, between 500 and 1000 feet.
The magnesian limestones of the Calciferous epoch in the West form bold
cliffs along the streams where they have been cut through by running water
and other agencies. An analysis of the rock is given on p. 84. It is often
oolitic.
b. Region of the Appalachians.—The Calciferous beds along the Appalachians
have their greatest thickness to the north. At Point Levi, near Quebec, whero
they have been called the Quebec group, they have been estimated to be 5000
176
PALAEOZOIC TIME—LOWER SILURIAN.
to 7000 feet thick (Logan). They consist of black and blue shales, gray sand
stone, with some conglomerate, beds of magnesian and common limestone
(some of them fossiliferous), slates containing graptolites, red and green shales
of great thickness, and, at the top of the series, a sandstone 2000 feet thick,
called the " Sillery" sandstone. Hunt has found some of the dolomitic conglo¬
merate to consist largely of green-sand (glauconite).
The rocks east of the Hudson, called Taconie rocks by Professor Emmons
(from the Taconic range lying along the western slope of the Green Mountains)^
have been referred to this epoch. (Hunt.) They consist of slates, quartz-rock, and
limestone, and include the marble of western Massachusetts and Vermont. Fos¬
sils, probably of the Trenton period, occur in the Vermont limestone (see p. 391).
Professor Emmons long since pointed out that these rocks were older than the
strata on the west side of the river, and, regarding them as pre-Silurian, has
called them the Taconic system. He has estimated the thickness at 20,000 feet.
The rocks dip at a large angle as the result of great dislocations and folds, and
the true thickness is of difficult determination. It is probable that the thick¬
ness estimated for the Quebec group is nearer the true amount, as has been
suggested by T. S. Hunt. The precise line between the Potsdam and Calciferous
strata in this Taconic series has not been ascertained. Continuing along the
Appalachians into Pennsylvania, we find the limestone strata predominating.
H. D. Rogers estimates the sandstone or lower part at much less than 1000 feet,
and the limestone portion at 1950 feet in the Kishicoquillas valley and 5400
feet in the Nittany valley.
In eastern Tennessee, also within the Appalachian chain, the earlier part of the
epoch is represented by laminated sandstones, some hundreds of feet thick;
above this, a magnesian limestone, often oolitic, estimated at 1000 feet in thick¬
ness, bluish below, grayish at the middle, and gray and cherty above.
The Calciferous rocks throughout the Appalachians have been greatly dis¬
turbed. The beds usually lie with their edges to the surface and dipping at a
large angle.
c. Eastern border.—At the Mingan Islands, in the Gulf of St. Lawrence, the
Calciferous sandrock occurs overlaid by a white limestone, which is probably
referable to the same epoch. Upon the latter rests the Chazy limestone. The
white limestone is fossiliferous, and none of the species are identical with known
Chazy forms, while several occur in the sandrock below.
Structural peculiarities.—[a.) The thin lamination of most of
the arenaceous beds is an important characteristic.
(5.) The layers of the Potsdam sandstone in New York, Canada,
Michigan, Wisconsin, and elsewhere, are frequently made up of
obliquely laminated layers, as in fig. 61 e, p. 93.
(c.) The layers in Michigan and elsewhere have sometimes the
compound character illustrated in fig. 61 /. This figure (by Foster
& Whitney) is from the Potsdam sandstone of Lake Superior.
((/.) Ripple-marks (fig. 62) are common on many of the layers of
the Potsdam sandstone in New York, Canada, and the West, and
also in sandstones of the Calciferous epoch in Missouri.
POTSDAM PERIOD.
177
(e.) Mud-cracks (fig. 64) characterize the layers in many places.
(/.) Wave-marks (§ 101) occur on some of the layers.
(g.) Siliceous or cherty concretions, and geodes of quartz crystals,
characterize many layers of the Calciferous epoch, both in New
York and the West. Even the limestones of Missouri are cherty
in some layers.
The above marks, b to/, are evidences, where they occur, either
that the deposits were formed in shallow waters (b, d), or as
emerged beaches or flats (d, e,f), or as wind-drifts over fields of
sand (c).
3. Minerals.—The minerals of the Potsdam formations have
already been partly enumerated. There are no important beds of
ore in New York. Iron-ores occur in Canada. The lead-bearing
rocks of Missouri and Arkansas are the magnesian limestones of
the Calciferous epoch ; and with the lead-ore (galena) occur also
valuable ores of cobalt, and the associated species, pyrites, barytes,
calc spar, etc. The copper-mines of the Lake Superior region are
in the rocks of this period; and some remarks upon them will
be found on page 195. Quartz crystals in great abundance occur in
cavities in the Calciferous rocks of central New York, and fissures
are often lined with crystals. Anthracite coal in small pieces is
found in some of the Calciferous beds, and fragments are at times
imbedded in the crystals of quartz, or lie loose in the cavities that
afford the crystals.
2. European.
Rocks of the Primordial period have been observed in Great
Britain, Scandinavia, Bohemia, and other countries.
In Great Britain they outcrop in the western half, especially in
North and South Wales and Shropshire. The rocks in Shropshire,
are hard siliceous grits and sandstones, and often stand out in rude
crags, as at the Stiper Stones; and they have in places ripple-marks,
wave-marks, mud-cracks, and worm-burrows [Scolithus), like the Pots¬
dam rocks of America. Their thickness is from 800 to 1000 feet.
They are much inclined, and rest, according to Murchison, "in con¬
formable apposition upon the upper edges of the Longmynd" rocks,
or the Cambrian, as the latter are called (a name first used by Sedg¬
wick). These Cambrian rocks are slates and sandstones, having the
estimated thickness of 26,000 feet; and although they have been
regarded as sub-Silurian, three or four fossils have been detected
in them,—viz.: two species of Sea-weed or Corallines (genus Oldha-
mia) at Bray Head, in Ireland ; and burrows of worms, and a frag¬
ment of a Crustacean, in Shropshire. In North Wales there are
13
178
PALAEOZOIC TIME—LOWER SILURIAN.
Lingula flags, likje those of the New York and Western Potsdam.
In northwest Scotland, beds referred to the Cambrian, consisting of
red and purple sandstones and conglomerates, overlie unconform-
ably the crystalline Azoic,—" the fundamental gneiss" (Murchison).
It should be here stated that Murchison places these Cambrian
beds on the same horizon with the Iluronian of Canada. The cor¬
rectness of this inference is not yet fully established. A large
portion of the crystalline rocks and schists of the Highlands of
Scotland are metamorpliic rocks of the Silurian age.
In Lapland, Norway, and Sweden, there is a Primordial sandstone
overlaid by schists, the lowest beds passing at times into a conglo¬
merate. They are the regions A, B of the geologist Angelin.
In Bohemia, the lowest Primordial beds are schists 1200 feet thick,
called by Barrande Protozoic schists, or the Primordial Zone, and
numbered C in his series,—his A, B consisting of schists and con¬
glomerates conformable to C. Until recently B was thought to
contain no trace of life, and therefore to be below the Primordial;
but within a short time worm-burrows have been reported by Dr.
Fritsch to occur in some of these inferior beds. The formation C
has been regarded as the equivalent of the Potsdam ; but it may
be necessary to add a part or all of B. Barrande's next division,
lettered D, consisting of schists, sandstones, and conglomerates,
corresponds to the rest of the Lower Silurian ; but the lower por¬
tion of it may represent the Calciferous epoch.
II. Life.
1. American.
As the life of the Potsdam period is the beginning of the system
of life deciphered in American geological history, great interest
attaches to it.
1. Plants.
Algcc, or Sea-weeds, are the only plants distinguished ; the species
are related to the Fucoids, or leathery sea-weeds, of existing coasts
(p. 167).
In general, the remains are stony, vermiform, branching fossils, wholly desti¬
tute of the original vegetable material. But in some places thin seams of
mineral coal have been found beneath or near fucoidal layers; and in Herkimer
co., N.Y.. the quartz crystals sometimes contain fragments of anthracite. The
lowest of these distinct fucoidal layers in New York occurs in the inferior
part of the Calciferous beds : it abounds in slender branched but irregular stems,
called Palmophycus irregularis II. (the name of the genus being from the Greek
for ancient Sea-weed or Fucus). In another and higher layer, the stems are as
POTSDAM PERIOD.
179
large as the finger; the species is the P. tubularis. A branched or palmate spe¬
cies is the Buthotrepkis antiqua H. Other species of Palmophycus occur in the
beds of the Calciferous epoch.
It is possible that the infusoria called Diatoms, now referred to the vegetable
kingdom, existed in the waters, and along with Sponges they may have been
a source of part of the chert and quartz in the beds. But no remains of these
microscopic species have yet been detected in so ancient strata.
The cylindrical upright stems, called Scolithus, common in the Potsdam beds,
are now regarded as the fillings of worm-holes.
2. Animals.
Among the animals of the Potsdam or Primordial period, though
few in species, three of the sub-kingdoms were represented,—the
Radiate, the Molluscan, and the Articulate.
The species are all marine ; none are proved to be of fresh-water
or terrestrial life. They included,—
1. Among Protozoans: probably Sponges (fig. 236 A) and Rhizopods.
2. Among Radiates: Crinoids, of the order of Echinoderms ; Grap-
tolites, supposed to be of the order of Acalephs ; and possibly coral-
making Polyps.
3. Among Mollusks: Bryozoans, Brachiopods,* Conchifers, Ptero-
* As Brachiopods are the most abundant fossils of the Silurian, their distin¬
guishing characteristics and the more important genera are here mentioned,
—taken principally from Davidson (Palseontographical Society publications).
1. Animal.—As stated on page 158, the living animal, unlike all other Mol¬
lusks, has (1) a pair of spiral arms, as shown in figs. 212 and 215; and to this
the name Brachiopod alludes, from the Greek for arm and foot. These arms
may sometimes be thrown far out of the shell, so as to bo used for taking food.
(2) The animal, as well as shell, is symmetrical either side of a vertical line let
fall from the centre of the hinge,—the line a b in fig. 213; and in this the species
differ from all the Conchifers (or Lamellibranchs). (3) There are no branchiae
(gills) apart from the pallium or mantle; and hence Brachiopods are often
called Palliobranchs.
2. Shell.—The characteristics of most importance are as follow:—
a. The large valve (see fig. 211 and others) is the ventral.
b. The form of the internal supports connected with the spiral arms varies
much, and often they are wanting. The loop-form is seen in figs. 208, 209, 210;
the spiral, in figs. 212, 215; the short process, in fig. 217; and they are wanting
in figs. 220, 221.
c. The general form and exterior markings of the shell afford important
characters ; the nearly equal convexity of the two valves, or a medial depression
on the ventral valve, with a corresponding elevation on the dorsal, figs. 211,
213.
d. The beak of the shell may be very large and full (figs. 211, 229), or very
180
PALAEOZOIC TIME LOWER SILURIAN.
pods, Gasteropoda (p. 156), and Cephalopods (p. 155). Thus, all the
grand divisions of Mollusks were represented. This cannot be said
of any other of the four sub-kingdoms of animal life. Even at the
small and little prominent (figs. 219, 220); may have an aperture or foramen
at apex (figs. 160, 213, 214), or not.
e. The hinge-line may be straight, or not; as long as the greatest breadth of
the shell (211, 219, 222), or shorter (217, 218).
/. The presence or not of a cardinal area (hinge-area); there is a large one
in fig. 211, and none in fig. 228.
(/. The presence or absence of a deltidium,—composed of one or two accessory
pieces occupying a triangular opening under the beaks, as seen in fig. 214.
Sometimes a similar opening at the middle of the hinge is partly or entirely
closed by the growth of the shell, so as to leave a triangular prominence, called
a pseudo-deltidium, as in Cyrtia, Streptorliynchus, etc.
h. The markings on the inner surface of the valves are of special importance,
and particularly the muscular impressions usually situated near the medial line
not far from the hinge : on the dorsal (or smaller) valve there are in the arti¬
culated genera two pairs (« and «' in figs. 217, 220, 224,220), sometimes coalescing
so as to be one pair, for the attachment of the adductor muscle (closing the shell):
one is usually in advance of the other, but in figs. 220 and 223 they are side by
side,- on the ventral (or larger) valve there is a single impression on the medial
line between two others (figs. 218, 224); the single impression is the insertion of
the adductor muscle (a, figs. 218, 221, 224, 227), and the pair are the insertions
of the cardinal muscle; the latter muscle terminates on the dorsal valve usually
in a small process.
Families of Brachiopods.
Terebratula Family (figs. 160, 208-210).—Having arm-supports of the form
of a loop attached to the smaller or dorsal valve, and a foramen at the apex
of the beak. Shell-structure punctate.
Spirifer Family (figs. 211-215).—Having spiral supports; shell usually with a
medial fold; hinge-line commonly long and straight (sometimes short); beak
large and full.
Rhynchonella Family (figs. 216-218).—Having the arm-supports short curved
processes; beak usually full, but narrow, and having a foramen; shell seldom
wider than high.
Orthis Family (figs. 219-227).—Arm-supports wanting; shell rarely with a
medial fold; shell varying between orbicular and D-shape; beak usually very
small, but sometimes produced.
Productus Family (figs. 228-230).—Arm-supports wanting; shell without a
medial fold, or almost wholly so; hingc-linc straight, often as long as the
breadth of the shell, or nearly so, and without a cardinal area, or with only a
narrow one (excepting in Strophalosia and Aulostc/jcs); surface often tubular-
spinous; form usually D-shape, with the dorsal valve very concave ; beak often
very large and full.
Discina Family (figs. 233-235).—Thin and small disk-shaped shells ; orbicular
POTSDAM PERIOD.
181
close of the Silutian age the Radiate type—the lowest of the four—
was less fully displayed in its subdivisions than the Molluscan.
4. Among Articulates: marine worms, and Crustaceans of the tribes
of Trilobites (figs. 242, 243, 245) and Ostracoids (p. 154).
or ovate; a slit or foramen through the ventral valve; no articulation between
the valves.
Linyula Family (figs. 161 and 236).—Thin and small shells; orbicular or sub-
ovate; no foramen; no articulation.
Besides these there are also the Crania and TItecidium families.
Genera of Brachiopods.—1. Terebratula Family.—Genus Terebratula, like
figs. 160 and 208 ; the loop small, as in fig. 209. Genus Waldheimia, the same,
the loop large, fig. 208.
Besides these genera, Tercbratulina has the side (or " crural") processes near the
base of the loop united (fig. 210). Another genus, Terebratella, has the sides of the
Figs. 208-215.
Fig. 208, Waldheimia flavescens; 209, loop of Terebratula vitrea; 210, id. Tercbratulina
caput-serpentis; 211, Spirifer striatus; 212, same, interior of dorsal valve; 213, Atliyris
concentrica; 214, 215, Atrypa reticularis, the latter dorsal valve.
loop united at middle by a cross-piece, and this piece soldered to the shell. Tere-
hrirontra has the beak extravagantly prolonged, so as to be longer than the dorsal
valve. Fensselaeria has, instead of a loop, a peculiar hastate brachial support,
projecting far within the dorsal valve. Stricklandia of Billings may be the same
genus, and, if so, it antedates Rensselaeria. Centronella seems to be intermediate
between Terebratula and Waldheimia. Other genera, rarely met with, are Tri-
(jonosemus, Megerlia, Mayas, Argiope, appearing first in the Cretaceous, and
Kraussia, Boucliardia, and Morrisia, known only in recent seas, with a possible
exception of the last. Strinrjoceplialus is another genus, probably constituting
a sub-family, occurring in the Devonian.
182
PALAEOZOIC TIME LOWER SILURIAN.
The most abundant fossils in the Potsdam beds are the shells of
the Brachiopod genus Lingula (figs. 237-239), and Trilobites.
The Lingulse are so numerous in some places as to give their
name to the rock : thus, there are the Lingula grits and Lingula flags,
2. Spirifer Family.—The genus Spirifer includes the common species, having
usually a long hinge-line and distinct cardinal area (figs. 211, 212). In Athyrix
(fig. 213) the hinge-line is much shorter, the hinge-area small or none, the beak
contracted and having a small round aperture. This genus is like Terebratula in
its narrow form, and beak without cardinal area, but has the spires of the Spiri-
Figs. 216-227.
Fig. 216, Rhynchonella psittacea, showing the spiral arms of the animal; 217, id. dorsal
valve; 218, id. ventral; 219, Stropliomena planumbona; 220, id. dorsal valve; 221, id.
ventral; 222, Leptama transversalis; 223, id. dorsal valve; 221, id. ventral; 225, Orthis
striatula; 226, id., dorsal valve; 227, id. ventral.
fers. Atrypa (figs. 214, 215) has the spires differently arranged, as in the figure ;
the form narrows to the beak, where there is no hinge-area or only a small one.
Uncttes has the beak extravagantly prolonged, and a large opening beneath it.
Cyrtia has nearly the same extravagant prolongation of the beak, but with a
large hinge-area, and a very small opening left at the top of the pseudo-deltidium.
POTSDAM PERIOD.
188
among the Primordial strata; and the same is true of a closely-
related shell of the genus Obolus (fig. 23G). Besides Brachiopods
of the Lingula family, there are others of the Orthis and Rliyncho-
nella families even in the Potsdam epoch.
Koninckina is an imperfectly determined genus, resembling Prod actus in form,
but differing internally.
Among other genera and subgenera of this family may be mentioned Cyrtina,
Retzia, Merista, Nucleospira, Trematospira, Rhynchospira, Charionella, etc.
3. Rhynchonella Family.—The genus Rhynchonella (figs. 216-21S) contains
plump-ovoid or subtrigonal shells, usually narrower than high, and narrowing to
the beak, having usually a foramen and no hinge-area; generally a U-shaped
flexure in the anterior margin of the shell. Pentamerus has a much fuller and
more incurved beak, and no area or deltidium, though there is a triangular
Figs. 228-236.
Fig. 228, Productus aculeatus, dorsal view; 229, Productus semireticulatus, ventral view;
229 a, section of Productus, showing the curvature of the valves; 230, Clionetes lata,
opposite views; 231, Calceola sandalina; 232, Crania antiqua; 233, Discina lamellosa, side-
view; 234, id. showing foramen; 235 a, l>, Siphonotreta unguiculata, opposite views; 236,
Obolus Apoliinis.
opening at the middle of the hinge, which usually becomes closed in adult shells
by the incurving of the beak. Camarophoria is a rare genus of the Carboni¬
ferous and Permian. Porambonites, a very plump shell of the Lower Silurian,
near Rhynchonella. Camerella of Billings is another genus of this family,
found in the Lower Silurian. Leptoccelia and Eatonia probably belong to this
family.
4. Orthis Family.—In the genus Orthis (figures 225-227) the species arc
usually rather thin; often orbicular, at times a little wider than high; both
184
PALAEOZOIC TIME LOWER SILURIAN.
Trilobites were the largest animals of the seas, and the highest in
rank. There were numerous kinds, and they varied in length from
a sixth of an inch to two feet. Fig. 245 is a diminished representa¬
tion of one of them: it is a species of Paradoxides [P. Harlani), from
the Primordial rocks of Braintree, near Boston.
valves in general nearly equally convex; the hinge-line usually not long, with a
small cardinal area; a few species resemble a narrow Spirifer, and have a medial
fold and long hinge-line. Orthisina has the hinge-area very large and reversed-
triangular, with a convex deltidiuin, and the shell subquadrate. Strophomejia
contains thin D-shaped species (figs. 219-221), with a straight hinge-line
about as long as the width of the shell, a very narrow hinge-area, the dorsal
valve often very concave, with the ventral bending to correspond, and the four
adductor muscular impressions in the same transverse line. Lepteena is similar
(figs. 222-224), but has the four muscular impressions of different character,
as seen in fig. 223, while in Strophomena they are as in fig. 220.
5. Productus Family.—In the genus Productus (figs. 228, 229) the beak is
very full; hinge-line usually a little shorter than the width of shell; no
true hinge-area, and no beak-aperture; the smaller valve concave; the surface
of the shell spinous, the spines tubular. The margin of the shell is prolonged
downward often to a great length, and sometimes closes around into a tube.
Chonetes (fig. 230) has a straight hinge-line, commonly as long as the width of
the shell, the form rather thin, with the beaks not full and prominent, resembling
Leptaena; smaller valve concave; hinge-edge of larger valve furnished with a
few spines. Strophalosia is much like Productus in form and spines, but is more
circular, and the shells have a hinge-area, and a regular hinge with teeth; it also
differs in being attached by the beak of the ventral valve. Aulostegcs is also
similar to Productus in general form and spines, but there is a broad triangular
hinge-area, and the beak is twisted somewhat to one side.
6. Piscina Family.—In Piscina (figs. 233, 234) the form is orbicular or oval and
the valves low-conical; there is a slit through the ventral valve, beginning at or
near the highest point. The genus Orbicula is hero included. Trematis is similar,
but one valve has the umbo or prominent point marginal, or the slit reaches
nearly to the margin. In Siphonotreta (fig. 235) the form is ovate, the beak
projects at the margin, is somewhat pointed, and has a small aperture. Acrotreta
has the perforate valve elevated into a high oblique cone.
7. Lingula Family.—Lingula (fig. 161) is narrower than high, and pointed at
the beak; valves equal, thin. Obolus (fig. 236) is rotund or rotund-ovate; valves
a little unequal, the dorsal valve being the smaller and least convex, as in most
Brachiopods; muscular impressions, six,—two medial, two lateral, and two very
near the umbos (fig. 236 b),—having some approximation to the Cranise. Obolella
Billings has still different muscular impressions, as shown in fig. 244 A.
8. Crania Family.—The genus Crania has internal markings, as in fig. 232, and
the shell was attached when living by the substance of one valve to a rock or
other support. Calceola (of doubtful relations) is like a cone flattened on one
side and closed with a lid, as in fig. 231; valves not hinged.
9. Thecidium Family,^—Thccidium contains thick-shelled species, higher than
POTSDAM PERIOD.
185
Besides these remains of Crustaceans, there are peculiar tracks,
found at Beauharnois and elsewhere in Canada, and called Protich-
nit.es (fig. 245 B), which are supposed to have been made by large
Crustaceans having stout legs like the modern Limulus: they are
anomalous in form, and need further explanation. A very different
kind of track, also first made known by Logan (fig. 245 A), occurs in
the same Canada rocks. It is six and three-quarter inches wide; and
one trail is continuous for thirteen feet. It has been regarded as
the track of a very large Gasteropod; but it is quite as probable
that it was made by the clusters of foliaceous appendages of one of
the great Trilobites,—these appendages being its locomotive organs.
Impressions of long marine worms have been reported from some
of the shales. Besides these, there are worm-holes in the Potsdam
sandstones—though now filled with rock—which are referred to
burrowing worms of the Arenicola family (so called from the Latin
arena, sand, and incola, inhabitant). They penetrate the rock verti¬
cally, and are often in pairs, as is now the habit of such worms. The
most common kind in the Potsdam sandstone is called Scolithus
linearis (fig. 240) ; and for a long time it was supposed to be the
remains of a fucoidal plant. They are so abundant in these de¬
posits of the Potsdam epoch that they serve to identify them in
different regions.
In the North American rocks of the Potsdam period, already
nearly sixty species of Trilobites have been found and described,
and over forty species of Graptolites. Although the species of
shells were not numerous, some kinds were exceedingly abundant,
and many layers are almost wholly composed of them.
If the Potsdam and Calciferous epochs were named from their
most characteristic species, the former would be the Lingula or
Paradoxides epoch, and the latter the Graptolite.
wide, having a pointed beak, very large triangular liinge-area, and internally
digitate muscular impressions; commenced in the Trias, and has a single living
species.
Davidsonia is a genus of rare occurrence and undetermined relations. There
is some resemblance to Leptmna ; but it has a pair of low and faint spiral cones
on the inner surface of the larger valve.
The following genera have species in the existing seas; and those having an
asterisk are known only recent. In the Tcrebratula family, the genera Tere-
bratula, Waldheimia, Terebratella, Megerlia, Kraussia,* Bouchardia,* Morrisia,
Argiope; in the Thecidium family, Thecidium; in the Rhynehonella family,
Rhynchonella; in the Crania family, Crania; in the Piscina family, Discina; in
the Lingula family, Lingula. There are no living species of the Orthis, Pro-
ductue, and Spirifer families.
186
PALAEOZOIC TIME LOWER SILURIAN.
The genera Lingula and Piscina are the only two in the animal
kingdom, as far as now known, that began with the primal life of
the globe, in the Potsdam epoch, and continued on, in a succession
of species, to the present time,—the species changing, but not the
genera. The analyses of the ancient and modern shells by T. S.
Hunt confirm the fact of the family identity between the ancient
and modern species (p. 68). Unlike nearly all other shells, they
have the constitution of bones, or are mainly phosphate of lime.
Another genus, Pleurotomaria, and also Nautilus, if the specimens
are rightly referred, commenced in the Calciferous epoch, and still
have living representatives, nearly equalling the Lingula in the
length of their history.
Characteristic Species.—1. Potsdam, Epoch.
Protozoans. — Sponges.— Fig. 236 A, Arclieocijo.th.us Atlanticus B., is
either a coral or a sponge (Billings): a re¬
presents the external form, diminished
one-half in size; h, a polished transverse
section (natural size), showing an irre¬
gularity of structure more like that of a
sponge than a coral. It comes from the
north shore of the Straits of Belle Isle.
A. Mingnnensis B. is another species from
the same locality.
Radiates. — a. Polyps.— No corals
have been found in this formation, unless
the Archeocyathus be of this nature.
h. Acaleplis.—Fig. 244, Graptolithus Hallianus Prout, from St. Croix, Minne-
Figs. 237-244.
l-'igs. 207, 238, Lingula prima; 209, L. antiqua; 240, Scolithus linearis; 241 a, b, Cono-
cephalus minutus, head and tail shields (X 4); 242, Dicellocephalus Minnesotensis
(XkO; 243, D. Iowensis; 244, a, Graptolithus Hallianus.
sota. For an explanation of the nature of Graptolites, see beyond, on page 190.
Fig. 244 a is an enlarged view of a branch.
POTSDAM PERIOD.
187
c. Echinoderms.—Stems of Crinoids, made up of a series of disks, have been
found at La Grange, Minnesota (D. D. Owen). They were probably Cystidean.
An impression of a single disk has been observed on the sandstone of Keese-
ville, N.Y.
Mollusks.—a. Bryozoans.—No Bryozoans are known of this period, unless
some of the Graptolites may he of this nature. (See p. 190.)
b. Brachiopods.—Fig. 237, Lingula prima Conrad, from Keeseville, N.Y.; 238,
same, from Lake Superior (Tequamenon Bay), and from St. Croix, Wis.; 239, L. an-
tiqua H., from St. Croix,—a much larger specimen than those of New York. Other
species of Lingulas have been described from the rocks of Wisconsin and Canada.
Oholus Apollinis, fig. 236, or a related species, occurs near the mouth of Black
River in Iowa (D. D. Owen). Obolus Labrador!cus Billings, is a species from
the north shore of the Straits of Belle Isle. Obolella Billings, is the name of a
related genus of which two species are from the Straits of Belle Isle, one from
Troy, N.Y., one from Wisconsin, and one (fig. 244 A) from the Black Hills
of Dakota. The genus Discina, or Orbicula (figs. 233, 234), begins in this
epoch, and a species is reported by D. D. Owen from the Wisconsin beds, and
Fig. 244 A. Fig. 244 B.
Obolella nana. Tlieca gregaroa.
another, by B. F. Shumard, from Texas. Orthisina festinata B., Camerella an-
tiquata B., are other Potsdam species of Brachiopods.
c. Conchi/ers.—None are known.
d. Pteropods.—Fig. 244 B, Tlieca (Pugiuncidus) gregarea M. & II., from the
Big Horn Mountains, lat 43° N., long. 107° W., where they arc crowded toge¬
ther in great numbers on the slabs. Tlieca primordial™ II., from Trempalcau,
Wisconsin, and Chippewa River. A Theca has also been found at Keeseville,
N.Y. Salterella rugosa B., and S. pulehella B., from the north shore of the
Straits of Belle Isle, may be Pteropods.
e. Gasteropoda.— Imperfect specimens resembling a Plewrotomaria and the
Ophileta compacta have been observed in Canada, and the former also at Keese¬
ville, N.Y. A Gasteropod of the form of a Oapulus occurs in Texas (B. F.
Shumard).
/. Cephalopoda.—Two species of Orthoceras occur in the Potsdam of Canada,
in the uppermost layers, along with great numbers of Linyula antiqua (or acu¬
minata). This discovery by Logan places the Cephalopods lower than they
were before known to occur.
Articulates.—a. Worms.—Fig. 240, casts of worm-holes of Scolithus line¬
aris H. The Fucoidea ? duplex II. (Foster & Whitney's Lake Superior Report,
pi. 23) probably belongs to another species of worm.
b. Crustaceans.—(1.) Phyllopoda.—No Phyllopods have been found in the
American beds, although they occur in the Primordial rocks of Great Britain.
188
PALEOZOIC TIME LOWER SILURIAN.
-—(2.) Trilobites—Fig. 241, Conoc.ephalus minutus Bradley, from Keeseville,
N.Y.: a, the head-shield or buckler, with the side-pieces wanting, none having
* The genera of Trilobites are distinguished mainly by the form and mark¬
ings of the head and tail portions of the body, and the eyes. The large anterior
segment is the head or buckler; the posterior, when shield-shaped and combining
two or more segments, the pygidium. The middle area of the head, which is
often very convex, is the glabella ; the parts of the head either side of the gla¬
bella, the cheeks ; a suture running from the anterior side of the eye forward or
outward, and from the posterior side of the eye
outward (s s in the figure), the facial suture; a
prominent piece on the under surface of the head,
covering the mouth, the hypostome. The eyes may
be very large, as in Dalmania (fig. 244 C), Phacops,
and Asaphus (fig. 320), or small, as in Homalonotus ;
or not at all projecting, as in Trinucleus (fig. 323):
and may also differ in position in different genera.
The glabella may be broader anteriorly, as in
Phacops, Dalmania, Trinucleus ; or broader pos¬
teriorly, as in Calymene (fig. 321), Bathyurus (fig.
201); and it may vary otherwise in form; or it
may be ill defined, as in Isotelus (fig. 320) and Illee-
nus (fig. 333). It may have no furrows across its
surface, or one or more up to four (or rarely five). The four may be numbered,
beginning behind, No. 1, 2, 3, 4 (fig. 244 C). These furrows may extend en¬
tirely across, or be divided at middle as Nos. 2, 3, 4 in fig. 244 C. Isotelus (fig.
320) and Illiemts (fig. 333) have none of these furrows; Trinucleus (fig. 323) has
No. 1 faint or obsolete; Asaphus (fig. 332), Homalonotus, and Bathyurus have
No. 1 entire; Dicellocephalus (fig. 242) has Nos. 1 and 2 entire, and 3 divided;
Calymene (figs. 177, 242), Dalmania, Crypheus, Ogygia, Cheirurus, Proetus, have
No. 1 entire and 2, 3, 4 divided, but 4 is sometimes obsolete. Sao (fig. 261 A) has
No. 1 entire and 2, 3, 4 divided, but there is a medial longitudinal depression in
which 2, 3, 4 from either side coalesce. In one group, the genus Lichas, the
glabella has, on either side, one or two longitudinal or oblique lobes (figs. 322,
409). The furrows, as shown in the genus Paradoxides, correspond to articula¬
tions of the body. They are mostly obliterated in the higher Trilobites where
the head-shield is most compact, and are most distinct in the lowest, like Para¬
doxides, being a part of that general looseness of body that marks inferior grade.
The position of the facial suture (see p. 154 and s s in fig. 244 C) affords cha¬
racters for distinguishing genera; also the number of segments of the body
(in Agnostus the number is very small, and the head and pygidium are almost
in contact); the continuation of the free movable segments to the posterior ex¬
tremity, or the union of the posterior into a shield (called the pygidium); in
some cases the breadth of the middle lobe of the body as compared with the
lateral, it being very broad in Homalonotus (fig. 410) ; the form of the fold of
the shell beneath the head at its anterior margin ; the shape of the hypostome;
the capability of folding into a ball by bringing the abdomen to the head, as in
Calymene, Isotelus, Phacops.
POTSDAM PERIOD.
189
been found united to the head; b, the pygidium. Other species of this Pri¬
mordial genus occur in northern Vermont, Labrador (Straits of Belle Isle),
and Texas. Fig. 242, Dicellocephalua Minnesotcnsia D. D. Owen, a trilobite six
inches long, from Lake St. Croix, Minnesota; fig. 243, D. Iowcnsis, pygidium,
natural size, from near the mouth of Black River, Iowa. The name of this
Fig. 245. Fig. 245 A.
Track of a Trilobite (X %)•
Fig. 245 B.
Paradoxides Ilarlani (X }{>)■ Protichnites7-notatus (X/"c).
genus is from <5o«:AAij, a shovel, and KtipaXrt, head. Fig. 245, Paradoxides Ilarlani,
reduced, from Braintrcc, near Boston. P. Vermontana and P. Thomjisoni are
species from Georgia, Vt., and the Straits of Belle Isle; the latter is over four
inches long. P. Bennetii is a large species from Newfoundland. Latlnjnrus
parvxdus and B. sencctus B. are from the Straits of Belle Isle. Pcltura liolopyya
is another trilobite, three and a quarter inches long, from Georgia, Vt. Species
of Agnostus, An'onelliia, and Dicelloccjdialns, besides Conocephalus, occur in
Texas. Arionellus? Oweni M. & II. is from the Black Ilills, Dakota, and the
Big Horn Mountains. Paradoxides anaphoides Emmons, is a large species
from the Taconic slates of Washington co., N.Y.; and Microdiscus quadricostatns
Emmons, a small trilobite, from Augusta co., Va., remarkable for a very narrow
glabella as long as the head, and a short body. Fig. 215 A, section (referred to
on p. 1S5) of a track, probably of a large trilobite, from near Perth, Canada,
described by Logan, who names it Climacticlinites Wilsoni. Fig. 245 B, track,
supposed to be Crustacean (p. 185), called Protichnites 7-notatus.
190
PALAEOZOIC TIME LOWER SILURIAN.
2. Calcifcrous Epoch.
The great inagnesian limestones of this epoch in the Mississippi valley rarely
contain a fossil, and only a few species occur in the Calcifcrous beds of New
York. Species are, however, numerouS in some of the limestone layers of the
Quebec group, and already 137 have been described from these strata.
Protozoans Sponges?—Archcocyathus Miiigartensis 13. occurs at the Min-
gan Islands, in the lower part of the Calcifcrous.
Radiates.—a. Polyps.—No Polyp-corals have been found, unless the Archeo-
eyathus belongs to this group. The genus Stenopora is represented among
the Canada beds and at the Mingan Islands, and a doubtful coral from Pliillips-
burgh is referred by Billings to Tetradium. But both arc probably genera of
Acaleph-corals,—that is, the stony secretions of Ilydroid Acalephs (see p. 1G2).
The square form and four rays of the cells of Tetradium suggest this reference
for that genus; and it is required for Stenopora by the minute size of the cells
as well as the relation of the corals to the tabulate Favosites and Pocillopora.
h. Acalephs.—Graptolites* arc common in the shales of this epoch, and 42
Canada species have been described by Hall. Figs. 246-248 represent the
GraptolitJuis Logoni II. from Canada, showing the centre of a group and the fur¬
cating mode of branching. They are supposed by Hall to have been spread
* The annexed figures illustrate the relations of the Graptolites to living spe¬
cies of animals. The fossils are never calcareous ; the texture is membranous
or a little horny, and usually only faint impressions are left in the rocks. No. 1
represents one of the branching Bryozoans, the Notamia loricata, and 1 a the
same enlarged. No. 2 is the Sertularia abietina, and 2 a the same enlarged.
Along the branches there are capsules containing bulbs for reproduction; the
bulbs pass out from the capsule when mature. No. 3 represents another species,
the Sertularia rosacea, and 3 a the same enlarged; 2 a has one of the bulb-
bearing capsules.
The prominent distinction in the corallum of the Bryozoans and Sertularians
is that in the former the cells have no internal tubular connection, while in the
latter the axis of the stem is tubular, and all of the cells communicate with one
Fig. 252 A.
POTSDAM PERIOD.
191
out over the bottom and fixed in the mud only at centre. They probably
grew at considerable depths. In fig. 24 G, which exhibits the centre of a branch-
Figs. 246-252.
Figs. 246, 247, 248, Graptolithus Logani; 249, 250, Phyllograptus Typus; 251, Graptolithus
pristis; 252, young of Graptolite.
ing group, as figured by Hall, a membrane unites the branches at base ; 247,
a portion of a branchlet; 248, same, enlarged. The delicate notching along
the margin is made by the cells of the several animals of the group. Figs. 249
and 250 are a leaf-shaped kind, the type of the genus Phyllograptus (the P. Typus
H.). [Fig. 251 is a species from New York, the G. pristis II., from the shales of the
Hudson River period.] Fig. 252 is regarded by Hall as a young Graptolite, from
the Canada graptolitic shales. Numerous such forms were found among the
impressions of Graptolites.
c. Echinodcrms.—Crinoidal remains are not common. Among them Billings
has distinguished some stems that probably belong to the genus Glyptonrinus
(see fig. 339 for a species of this genus), and a fragment of the head of a Cystid-
ean near Palseocystites tenuiradiatus II. of the next, or Chazy, epoch. There are
fragments of several other species.
Mollusks.—a. Bryozoans.—A Stromatopora (a massive coral consisting of
thin layers that are made up of minute cells, a species of which is common in
the Trenton period) has been found at Phillipsburgh, Canada (Billings).
b. Brachiopods.—The Lingula family is no longer the most prominent among
Brachiopods : the Orthis family takes precedence. Along with it occur species
of the Rhynchonella family, as in the Potsdam.
Fig. 253, Orthis (Orthisina?) grandmva B. Other Brachiopods are Lingula
acuminata Con., Orthis parva ? Pander, Camerella calcifera B., a species of
Leptsena, and of Strophomena.
c. Conch if ers.—The first of this group yet reported is the Conocardium Blumen-
bachii B., found at the Mingan Islands in the White limestone (p. 176), a shell
another and with the tubular axis. In the fossilized specimens it is often diffi¬
cult, as would be inferred from the above figures, to determine which is the
fact; and hence there are some doubts as to the relations of the Graptolites. It
is quite possible that, while most of the so-called Graptolites are Sertularian
(that is, Aca.lephs), some are Bryozoan (or Mollusks).
192
PALAEOZOIC TIME LOWER SILURIAN.
related to Cardium, and belonging to the division of Conchifers having a si-
phonal tube. This division, the sinupallial, was far less common in the Silurian
Figs. 253-260.
Fig. 253, Orthis (Orthisina?) grandseva; 254, Ilelicotoma uniangulata; 255, Opliileta levaia,
256, Ilolopea dilucula; 257, 259, Ortlioceras primigenium; 258, 0. laqueatum; 200, 200 a,
Leperditia Anna; 260 b, same, natural size.
than the integripallial, or that in which the tube was wanting; and it is there¬
fore the more remarkable that the species first made known should have this
high characteristic. Mr. Billings remarks that there are indications on the
shell of the existence of the siphon (see p. 157). For illustrations of the genus,
see figs. 331 and 457.
d. Gasteropods.—Many genera of Gasteropods are represented in the Calcife-
rous rocks; and in all the aperture of the shell is without a beak (see p. 156).
These genera are in part of the Trochus family.
The following are characteristic species :—Fig. 254, Helicotoma (Euomphalu*
formerly) uniangulata H. ; 255, Opliileta levata V.; O. complanata V.; O. com-
pacta, a fine species from Canada, one and a half inches across; 256, Jlolopect
dilucula; Pleurotomaria Calci/era B., from near Beauharnois, Canada; P. gre-
garia B., from St. Ann's, Canada, extremely abundant; Maclurea matutina H.,
from New York and Canada; Murchisonia Anna B. (a long turretcd shell, ap¬
proaching the 31. hellidncta, fig. 306), from St. Ann's, on the island of Montreal,
and also the Mingan Islands, in the White limestone and the sandrock below;
Ecculiomphalus Canadensis B. (a shell three inches long, having the form of a
curved horn without transverse partitions within); E. intortus B., a smaller species.
e. Cephalopoda.—This highest tribe of Mollusks is well represented, though
less abundantly so than in the next period. The chambered shells of these
species in this period are either straight or nearly so, like a long, tapering horn,
as in Ortlioceras (whence the name, from the Greek opQus, straight, and icspas,
horn); or arched or partially coiled, as in Lituites; or completely coiled, as in
Nautilus. Figs. 257, 259, Ortlioceras primigenium V., a species having the septa
or partitions very closely crowded; 258, O. laqueatum II. Other species are 0.
LamarcM; Lituites Farnsicorthi B., a large species partially coiled and nearly five
inches in its longer diameter; L. imperator B., a still larger species, 101 inches
across, having the first three whorls coiled in contact. These Lituites are from
the upper part of the Calciferous sandrock of Phillipsburgli, Canada East. They
appear to be among the largest of the Ceplialopods, and, along with the Nau¬
tilus, the highest species of Mollusk in the Potsdam period.
POTSDAM PERIOD.
193
Articulates Crustaceans : Tvilobites.—Over forty American species of
Trilobites of the Calciferous epoch have been described. They belong to the
following genera:—Dicellocephalus, Bathyurus, Arionellus, Menoceplialus, Cono-
cephalus, Amphion, Agnostus, Cheirurus, and Asaphus. They are for the most
part the same that characterize the Potsdam, but the genus Paradoxides is
wanting, Dicellocephalus and Bathyurus are more numerous in species, and
Agnostus, Cheirurus, and Asaphus are new additions to the tribe. Asaphus
and Cheirurus have their fuller development later in the Silurian.
Pig. 261 represents the Bathyurus Saffordi B., a common species; a, the gla¬
bella, b, the pygidium. Some of the other species are Agnostus Americanus B.
Fig. 261.
Bathyurus Saffordi.
(Fig. 259 A represents a foreign species of this genus), A. Canadensis, Dicelloce¬
phalus magnijicus B., a species eight or nine inches long, Arionellus cylindricus
B., Bathyurus capax B., Cheirurus Apollo B., Asaphus illsenoides B., all of which
occur in the Quebec group, which has afforded in all thirty-six species of Trilo¬
bites. Phillipsburgh, C.E., and the Mingan Islands have afforded other species
of the genera Bathyurus, Amphion, Asaphus, and Menocephalus.
Ostracoids.—Besides Trilobites, there are the earliest of the bivalve Crusta¬
ceans,—very small species having the body enclosed in a bivalve shell somewhat
like a clam-shell, whence the name Ostracoid. Fig. 260, Leperditia Anna, from
St. Ann's, Canada, side-view; 260 a, same, in profile; 260 b, a group of the same
in the rock, natural size.
3. Species of Wide Range.
The following species continue from the Potsdam epoch into the Calciferous :
—Lingula acuminata, Ophileta compiacta, Archeocyathus Minganensis.
According to the latest investigations, the Calciferous and Chazy epochs are
wholly distinct in life. The Orthoceras laqueatum (fig. 258), referred to the
Calciferous, is suspected to be exclusively a Chazy species; the specimen from
which it was described as Calciferous was of uncertain locality.
2. European.
The Primordial life of Europe was quite similar to that of Ame¬
rica. The rocks contain sea-weeds (Fucoids) allied to Palseopliycus.
The lower sandstones are penetrated by the burrows of sea-worms
(Scolithus). Graptolites occur in Sweden in the upper slates ; and
the shells of Lingulse are in so great numbers as to give the name
14
194
PALAEOZOIC TIME LOWER SILURIAN.
of Lingula flags to some of the beds. Trilobites are the prominent
life of the period.
Characteristic Species.
Sea-weeds.—Besides the Fucoids, there are two species of Oldhamia
found in the Cambrian rocks of Ireland,—fig. 256 A, Oldhamia antiqua ; 257 A,
0. radiata. They were supposed hy Forbes to be Bryozoan, hut are generally
regarded as Sea-weeds or Corallines.
Figs. 256 A-262 A.
Fig. 256 A, Oldhamia antiqua; 257 A, 0. radiata; 258 A, Lingula Davisii; 259 A, Agnostus
Rex: 260 A, Olenus micrurus; 261 A, Sao hirsuta (X > 262 A, Hynienocaris vermi-
cauda (X %)■
Radiates.—Of Polyps, none; of Acalephs, Graptolites; of Eehinoderms, a
few species of Crinoids of the family of Cystids; occurring in Bohemia.
Mollusks.—Brachiopods.—A few species of the Lingula and Or this family.
Fig. 258 A, Lingula Davisii of the Lingula flags of North Wales. Conchifers.—
One species is reported as occurring in Great Britain. Pteropods.—There are a
number of species of Theca in Bohemia, Sweden, and England.
Articulates. — Trilobites are more numerous in species than any other
group. Over seventy have been found in Scandinavia, and nearly thirty in Bo¬
hemia. The common genera are Paradoxides, Agnostus, Olenus, Conocephalus,
Ellipsocephalus, and Sao: Fig. 259 A, Agnostus Rex, from Skrey, in Bohemia;
fig. 260 A, Olenus micrurus Salter, from the Lingula flags of North Wales; flg.
261 A, Sao hirsuta, of Bohemia.
Phyllopods appear first in this period, occurring fossil in the Primordial rocks
of Great Britain. Fig. 262 A is the Hymenocaris vermioauda, from North Wales.
It is like a shrimp in form, hut has no projecting movable eyes. Moreover, in
place of ordinary legs, if a true Phyllopod, it had foliaceous appendages, which
were too delicate to he preserved (whence the name, from (pvWov, leaf, and irovs,
foot). The existence of such Crustaceans at the present day, and the absence
in the fossils of feet and of pedicellate eyes, are evidence that the species are
of this type.
III. Igneous Action and Disturbances.
Through New York and the greater part of the West no evidences
of disturbance have been observed that can be traced to the
Potsdam period. The rocks are for the most part nearly horizontal
POTSDAM PERIOD.
195
and in general little altered, and the tilting which is observed ap¬
pears to have taken place in a later period. These remarks apply
to the larger part of the Potsdam rocks about Lake Superior. But
on Keweenaw Point, the famous copper-region of Lake Superior,
the sandstones of this period are associated with trap,—an igneous
rock that was ejected through fissures opened in the earth's crust;
and these trap ejections have added vastly to the accumulation, so
that in some places about Keweenaw Point the alternations of
sand-stone, conglomerate, and trap rocks make a thickness of eight
to ten thousand feet. Some of the conglomerate (according to
Foster & Whitney, and Owen) seems to be made of volcanic
scoria, like the tufa of modern volcanoes, as if the ejections were
submarine and the cool waters had shattered the hot rock to frag¬
ments and so made the material of the conglomerate ; and, as many
of the masses are not rounded, these authors infer that it was piled
up rapidly during the igneous action. Dr. D. D. Owen represents the
trap as often in layers alternating with shale and other rocks, indi¬
cating eruptions at different times. The trap rocks of Lake Supe¬
rior present many scenes of basaltic columns of remarkable gran¬
deur. Some of them are represented and described in the Geolo¬
gical Report on Wisconsin, Iowa, and Minnesota, by Dr. Owen.
The native copper of the Lake Superior region is intimately
connected in origin with the history of the trap and sandstone.
The copper occurs in irregular veins in both of these rocks near
their junction ; and whenever the trap was thrown out as a melted
rock, the copper probably came up, having apparently been derived
from copper-ores in some inferior Azoic rocks through which the
liquid trap passed on its way upward. The extent to which the
rock and its cavities are penetrated and filled with copper shows
that the metal must have been introduced by some process before
the rock had cooled. The nature of this process, and the condition
of the metal (whether as a salt or other compound in solution, or
in vapor), have not yet been ascertained. One great sheet of copper
which has been opened to view in the course of the mining was
forty feet long, and weighed, by estimate, two hundred tons. The
copper is mixed with native silver; and some specimens are
spotted white with the more precious metal.
In addition to copper, the rocks contain the usual trap minerals,
—zeolites, datholite, calcite, quartz; and some calcite, datholite,
and analcime crystals were formed about threads of copper.
Besides the disturbance connected with the Lake Superior
rocks, there were great oscillations of level over the continental
seas, causing the changes in the depositions from sandstone to
196
PALEOZOIC TIME—LOWER SILURIAN.
limestone or shale, and the reverse. These oscillations are the
subject of brief remark in the next section, on the geography of
the period.
IV. General Observations.
1. North American Geography.—On p. 136 a map is given pur¬
porting to represent the general outline of North America at the
close of the Azoic period. It is there stated that there may have
been other lands above the water, especially about the summits of
the Rocky Mountains and the regions beyond, making islands,
large and small, in the great continental sea; but that the conti¬
nent, in a general way already defined as to its ultimate outline,
lay at no great depth beneath the surface of the water. The facts
gathered from the rocks of the Primordial period throw additional
light on early American geography.
(1.) Northern border of the interior basin.—We learn from the beds
of the first or Potsdam epoch that along the northern border of
the United States the waters were shallow, and that there were
beyond doubt coasts and exposed sand and mud flats. The ripple-
marks, so common in the strata both of New York, Canada, and the
West, must have been formed either along a sandy beach or over
a shallow bottom. The alternation of oblique and horizontal
lamination in many layers (fig. 61 e, p. 93) is evidence of ebbing
and flowing tides. The wave-lines show where the waves actually
dashed over the sands of a coast. The various inclinations of
the lamination (like fig. 61 /, p. 93, drawn from the Michigan Pots¬
dam beds) point out the rocks as once wind-drifts of sand that had
been decapitated again and again by storms; and the tracks of
crustaceans, as Logan has observed, as well as the mud-cracks,
could only have been made upon land above the level of the sea.
The worm-burrows (Scolithi) in the sand-rocks were made in the
sands near tide-level, or not far below. In fact, sandstone itself, as
will be shown in a future chapter, is evidence to the same purport;
for the sands as well as pebbles of marine formations are accumu¬
lated only along shores and within a narrow range of soundings.
Hence the prevailing sandstones and conglomerates of the Pots¬
dam formation indicate that there were no deep seas where these
rocks were laid down. Thus, from New York through Canada,
Michigan, Wisconsin, Minnesota, Iowa, and Nebraska, to the Black
Hills, and the Laramie Range on the Rocky Mountains, we are en¬
abled to run a line of soundings for the Potsdam period. When the
layers of the Potsdam sandstone that now skirt the Black Hills of
Dakota were forming, the hills stood above the sea, and the
POTSDAM PERIOD. 197
materials of these layers were the moving sand and pebbles of the
shore.
(2.) Interior basin.—South of this northern line, over the interior
continental basin, whatever Potsdam rocks exist are mostly con¬
cealed from view; so that we fail of direct evidence as to the depth
in that region. The rotfks in Texas, however, bear the same testi¬
mony as those of the North. But we have indirect evidence with
regard to the depth of the interior basin, in the facts observed
along the Appalachian region, its eastern border. The sandstones
and conglomerates of northern Vermont, Pennsylvania, Virginia,
and Tennessee, afford proof of shallow waters and emerged flats
like those of New York and the States west. There are more
shales; but the interstratified sandstones still show that there was
no deep ocean along the Appalachian region. Moreover, in Pennsyl¬
vania, Virginia, and Tennessee there are worm-burrows in the
sandstones, as in New York. Thus, we make out a region of shal¬
low waters and exposed sands along the Appalachian region, during
a part at least of the Potsdam epoch. If, then, there were shallow
waters on this eastern border and along the north, we may feel
confident that there were no deep seas over the interior basin,
although it is probable that the waters deepened from the northern
coast-lines southward; and, as the Appalachians follow the general
course of the existing coast, there is ground for full assurance that
the general shape of the future continent was marked out in that
early period.
(3.) Eastern border.—On the eastern border of the continent, in
Newfoundland, and at Belle Isle, there is similar evidence of shallow
waters or emerging sands. Besides the occurrence of a considerable
thickness of sandstone, the rock at Belle Isle contains the borings
of the Scolithus. There are also fossils ; and above the sandstone
occur beds of fossiliferous limestone, which may be additional
proof that the seas were not very deep.
(4.) Appalachian region.—But the great thickness of the deposits
along the Appalachian region gives further evidence that the future
history of the Atlantic border was already foreshadowed in Primor¬
dial time.
Even the shales which abound in these Appalachian beds are no
proof of deep seas, as such deposits form along coasts and not in
the depths of an ocean. A few hundred feet, or a thousand at
most, are all the depth that can be deemed probable for the form¬
ation of any shale. This is proved by the facts in existing seas.
They may originate in deeper waters; but such cases are exceptions.
Moreover, at Georgia, in Vermont, where the rocks are shales, the
198
PALAEOZOIC TIME LOWER SILURIAN.
large Trilobites indicate that the beds are rather the accumulations
of sheltered bays than of deeper off-shore waters. The fossils of
Swanton, Vermont, suggest the same conclusion. The interca¬
lated sandstones and conglomerates, and even the limestones
of the Quebec group, Taconic rocks, and the Primordial series in
other parts of the Appalachians, require, for each, moderate depths
at intervals, in the progress of the great formation.
But, taking the facts as allowing of even a thousand feet of depth
for the deposition of a large part of the shales (instead of the one
to four or five hundred feet which we deem more probable), there
are still several multiples of this thickness to account for along this
Appalachian region. The facts, therefore, show that this border
portion of the continent must have been subject to great oscilla¬
tions, resulting in a subsidence nearly equal to the thickness of the
deposit. The oscillations were such as would produce the alterna¬
tions of rock in the series, bringing the land near or to the surface
for the accumulations of sandstones and conglomerates, and de¬
pressing it again somewhat for the shales. These were early move¬
ments in that system of change which resulted in the evolution of
the Appalachian chain.
The transition from the region of these oscillations to the interior
basin is singularly abrupt, as shown by the wonderful contrast in
the thickness of the strata. This contrast has been made still
stronger in later time by the foldings and disturbances along the
Appalachians. The boundary between the two is the course of a
series of great faults in the strata,—as has been pointed out by
different geologists,—which follows the general direction of the
Appalachian chain. Directly on its course are the waters of the
Hudson and Lake Champlain. From the north extremity of
Lake Champlain, as Logan has mentioned, the line stretches north
to Quebec, on the St. Lawrence, thence follows the river, and,
finally, bends around to Gaspe on the Gulf of St. Lawrence. In
consequence of the faulting, the rocks of the Potsdam period on
the east side were raised several thousand feet above the level
of those on the west. The existence of this line of faults was
predetermined in the oscillations; but when it was made is not
ascertained. It was natural that the oscillation of the unstable
border of the continent against the more stable interior should
sooner or later have ended in such a catastrophe.
(5.) Change of condition between the Potsdam and Calcifcrous epochs.—
In passing from the Potsdam to the Calciferous epoch, there was
a change in the condition of the continental seas, so that the rocks
afterwards made were to a considerable extent limestone: it is
POTSDAM PERIOD.
199
probable that this change consisted in a deepening of the waters
through subsidence. In the Potsdam epoch the continent, when
the rocks were forming, lay for the most part near the water's
level, washed by the ocean's tides,—a condition favorable for the
accumulation of sand deposits. In such a case the waters would
be too impure from disturbed sediment for the formation of lime¬
stone. Such an amount of subsidence was therefore required as
would give clear and pure waters,—perhaps not more than a hun¬
dred feet; for the limestone of the coral islands is all made within
that depth. Moreover, the alternations of sandy strata with lime¬
stone, so marked in Missouri, imply several oscillations of level
over the interior basin during the Calciferous ejwch. These oscil¬
lations are also indicated by the succession of strata in the Quebec
group and in other parts of the Appalachian region. To the east,
at the Mingan Islands, there were sandstone deposits in the earlier
part of the Calciferous epoch, but others of limestone before its
close.
(6.) Lake Superior Sandstone beds and Trap rocks.—The deposits of
the Potsdam period in the vicinity of Lake Superior differ from
others of the interior basin in their great thickness (p. 195); but they
are also peculiar in their connection with the eruption of igneous
rocks. The evidences of igneous eruption are very numerous on
both the north and south shores of the lake ; and Isle Royal, stand¬
ing in the lake, abounds in trap rocks of this period. Such a
region of fires might naturally be one of extensive subsidence,—no
uncommon phenomenon in volcanic countries. This would give
an opportunity for the formation of thick deposits ; while if the
waters had been permanently shallow the marine formations must
have been thin, as they are in the peninsula of Michigan; for
they could not have much exceeded the depth of the waters. This
region of Lake Superior and the other great lakes lies directly
against the Azoic ; that is, it is between the region of progress on the
south, which was undergoing frequent changes of level through the
Silurian ages, and the more stable Azoic of the north. Here the
series of depressions were formed which are now the lakes ; and
these igneous eruptions through the fractured crust of the earth
seem to have been an incident in the subsidence that was producing
the basin for the largest of all the lakes, Lake Superior. Lake
Champlain also lies along the borders of the Azoic, and has the
Silurian of New England on its opposite side.
The thick sandstones, conglomerates, and shales of the ILuronian.
series occur in this same lake-region, and seem to show that the
first commencement of the lake-history dates as far back at leant
200
PALEOZOIC TIME LOWER SILURIAN.
as the Huronian period in the Azoic. The depression may not
have begun at that time ; but the subsidence attending the forma¬
tion of the thick deposits was an early one in the series that ended
in giving the main features to the present lake-region.
(7.) Atlantic currents.—From the map, p. 13G, it is apparent that
the northern oceanic current of the Atlantic would have traversed
New England, New York, and the Appalachian region to the south¬
west, while the warmer Gulf Stream would have in part followed its
present course and partly have flowed over the Gulf of Mexico and
up the interior sea of the continent. .
2. Origin of the material of the rocks.—(1.) Sandstones, shales,
and conglomerates.—The Azoic age had left the earth with a surface
of rock more or less covered with gravel and sand both above and
below the water. The waves, running streams, and slow wear and
decomposition through atmospheric causes, were working out their
legitimate results during the closing part of the age, as well as
earlier when the Azoic rocks themselves were accumulating. The
surface could not have failed to be extensively spread with earth,
and, at the opening of the new age, this earth or gravel would have
made the sand-flats and higher fields that were exposed over the
half-submerged continent, as well as the bottom of the seas.
From this material and the accessions derived through subse¬
quent wear and decomposition, all the Potsdam beds and all later
rocks of mechanical origin (exclusive of limestones) have to a great
extent been made. This material has been worked over again and
again, the accumulations of one age being in part distributed anew
to make the rocks of a later; and by this means the geological
series, with the exception stated, has been in the main built up.
The rocks of igneous origin have added to the stock only an in¬
considerable proportion of the whole amount, and those of che¬
mical origin a much smaller fraction.
The beds of sandstones, shales, and conglomerate of the Potsdam
period, we thus conclude, derived their material from the sand-
flats, from the higher gravel-fields which the encroaching waves
and running waters would level and carry off, and from the rocky
Azoic hills and mountains that were subject to degradation by
streams and decomposition. In an age without land-vegetation to
bind the soil, the degrading-process would have been more com¬
plete than at the present time. These materials were spread out
in layers by the waves and currents over the continental regions;
and the animals, which had a living-place in the mud or sand,
found there a burial-place also, to remain in many instances as
fossils, in attestation of the life of the period.
POTSDAM PERIOD.
201
(2.) Limestones.—The limestones of the Silurian and later ages
have nearly all been made through the wear and accumulation of
shells, crinoids, and corals, or the calcareous relics of whatever life
occupied the seas. The great limestone formations of existing coral
seas are modern examples of the process.
Among the beds of the Potsdam period, the magnesian limestone
strata of the Quebec group contain numerous fossils, and thus show
that they are marine, and that they have the origin above men¬
tioned. The extensive magnesian limestones of the Mississippi
valley have the same composition, and are similar in compactness:
and the natural inference is that they were also of organic origin.
But over extensive regions they do not contain a single fossil. Yet
it is to be remembered that the sea which grinds pebbles and
sand and makes fine sandstones may also grind shells and make an
impalpable limestone. This is abundantly exemplified in coral-
regions ; for a large part of the limestone there made of corals and
shells is as compact and unfossiliferous as the magnesian limestone
in question.
The only other mode of origin is by chemical deposition. This
could not have taken place in the open seas; for, owing to the
oceanic currents, the waters have a remarkable uniformity of com¬
position, and no local depositions can take place. It requires, there¬
fore, an elevation above the sea, and the existence of calcareous
mineral springs,—and springs on a wonderfully vast scale, for a
formation as extensive as the one in question. Such a condition
of things is improbable. Moreover, the depositions would have a
structure wholly unlike that of the magnesian limestone. Who¬
ever has seen the travertine beds of Tivoli—which are the largest
of the chemical calcareous deposits formed in the present era—will
appreciate the wide distinction between a mass made up of a series
of incrustations curving with all sorts of fantastic irregularities,
and the dense, even-grained limestone of the Calciferous epoch.
The oolitic structure of part of this limestone has a parallel in the
oolitic coral rock of Key West, which is also without imbedded
corals or shells.
It is not impossible that the strata may have been made of
microscopic organisms: the shells of Rhizopods, which have con¬
tributed so largely to chalk (though not commonly distinguishable
in the mass), have been detected in the Lower Silurian of Russia,
in " gr*een-sand" like that of the Potsdam period (pages 174 and
17G), and abundantly in the "green-sand" of the Cretaceous forma¬
tion ; so that the existence of this material leads the geologist to
suspect at once that of the Rhizopods.
202
PALAEOZOIC TIME—LOWER SILURIAN.
Another supposition is this: that the continent may have had its
borders so raised that the interior was a salt-water sea, shut off from
the ocean, and here the waters—more calcareous in that period
than now—deposited the limestone ; and that new accessions of
calcareous material might have been received either through occa¬
sional incursions of the ocean, or through streams flowing from the
land. A rock thus made, supposing the method possible, might be
much like the Silurian limestone in compactness and texture.
3. Climate.—No marked difference between the life of the Pri¬
mordial rocks in warm and cold latitudes lias been observed; and
there is wanting, therefore, all evidence of a diversity of climate
and of oceanic temperature over the earth's surface. With a warm
and equable climate, the atmosphere would have been moist and
the skies much clouded, hut storms would have been less frequent
or violent than now. The eyes of the Trilobite, as Buckland ob¬
serves, indicate that there was the full light of day, and therefore
that sunshine alternated with the clouds as now.
4. Life.—(a.) Grades of life.—The system of life began (1) with
marine species; (2) with species of three sub-kingdoms, those
of Radiates, Mollusks, and Articulates; but (3) with the inferior
species in each : the Sertularids being the lower Acalephs ; Crinoids
the lower Echinoderms; Brachiopods the lower Mollusks; and
Lingula and Orthis among the lower Brachiopods; Gasteropods
(Univalves) with an entire aperture to the shell, the lower of Gastero-
podan Mollusks ; Orthocerata, or the straight-shelled Cephalopods
with plain septa, the lower of Cephalopodan Mollusks; marine
worms, the inferior group of Articulates; Trilobites, Pliyllopods,
and Cyprids among the lower of Crustaceans ; and Paradoxides and
the associated genera of Trilobites among the lowest of the group
of Trilobites. None of the genera of ornamented modern sea-shells
have been observed, and none of those having a beaked aperture
to the shell; no land or fresh-water shells ; no shrimps, lobsters, or
crabs (Macrourans or Brachyurans); no insects; no relics of fishes,
reptiles, or mammals.
While, however, the species were inferior species in the tribes
represented, they were not necessarily the very lowest. For Polyps
are, as a class, the lowest of Radiates, and yet it is not certain that
any Polyp-corals were in the Primordial fauna,—none being re¬
ported from the European Primordial period, and those so called
found in the American rocks being probably Sponges. Trilobites,
although belonging to the inferior of the grand divisions of Crusta¬
ceans, the Entomostracans, stand at the head of that division, if
not intermediate between them and the Tetradecapods, the next
POTSDAM PERIOD.
203
higher grouji. The Phyllopods are other Entomostracans, and
in some respects they constitute a group of high grade, having
affinities with the Macrourans as shown in the general form of the
species. The Trilobites and Phyllopods are examples of compre¬
hensive types (synthetic of Agassiz),— types comprehending, along
with their own characteristics, some of those of other tribes which
were yet uncreated, but which were to exist in the future unfold¬
ing of the system of life.
As far as has been deciphered in the history of the Primordial
period, there was no green herbage over the exposed hills ; and no
sounds were in the air save those of lifeless nature,—the moving
waters, the tempest, and the earthquake.
(b.) Exterminations.—The life of the Potsdam period changed
much during its course, and at one time—the close of the first
epoch—there was nearly a complete extermination of the species,
requiring a repeopling of the seas for the succeeding epoch. Two
or three species, including a Lingula, exist, but the others do not
reappear. Among the Trilobites, the genus Paradoxides, some of
whose species were the largest of known Crustaceans, became en¬
tirely extinct; most of the other genera remained, but were repre¬
sented by new species.
At the end of the Calciferous epoch there was a second exter¬
mination, obliterating wholly the life of the Primordial period.
Some species had disappeared before in the progress of the epoch,
for these destructions were not confined to the grander transitions
in the strata; and there had also been new additions to the species
at intervals, judging from the successions in the Quebec rocks.
These exterminations and creations in the progress of a period, and
more general exterminations and creations at the end of an epoch
or period, were a common feature throughout the earth's geolo¬
gical progress.
5. Reality of the Primordial or Potsdam period in America, and
its equivalency with the European.—The fact that the Potsdam
and Calciferous epochs constitute together one period in the history
is shown by the transitions of the strata, and more especially by
the resemblances between the two in living species. This has
become more apparent since the recent discoveries in the Canadian
geological survey under Sir William Logan. The types of life of a
period are of two classes : those of one class are characteristic of
the period, and have their fullest exhibition in its course ; the others
look onward to a fuller expression in some part of future time.
The genera of Gasteropods and Cephalopods are of the latter kind ;
for Pleurotomaria, Maclurea, Orthoccras, and other genera of these tribes
204
PALAEOZOIC TIME LOWER SILURIAN.
have only their beginning here; they have a much larger repre¬
sentation in species during later periods. But the genera of Trilo-
bites are in a large degree peculiar to the Primordial. Paradoxides,
Peltura, Dicellocephalus, Menocephalus, Arionellus, Conocephalus, have
their whole existence in the Potsdam period. The first two are
eminently Primordial in character. The others approximate more
to genera of the next period.
The correctness of uniting the Potsdam and Calciferous epochs
in one period is apparent in the number of these Primordial genera
of Trilobites which the two epochs have in common. Paradoxides
and .Peltura are alone in being confined to the first epoch. The
others mentioned have species in both, and there are quite a
number of Calciferous species of Dicellocephalus, Bathyurus, and
Conocephalus.
The equivalency or synchronism of the European and American
Primordial period is looked for, not in the sameness of species,—for
none are known to be common to the two continents, although one
or two are so suspected,—but in an identity in a prominent part of
the genera. In accordance with this, we find the life of the world
on both sides of the Atlantic commencing with species of Lingula,
Obolus, Orthis, Theca, Scolithus, and the Trilobites, Paradoxides,
Peltura, Conocephalus, Arionellus, Agnostus, and others.
But, while a general equivalency is apparent, there are marked
peculiarities, which are brought out especially in the later part of
the American Primordial. There are Gasteropods (Pleurotomarife)
and Cephalopods (Orthocerata) even in the earlier epoch of the
American Primordial, while no species of either group have been
reported from any part of the European ; and in the later Ame¬
rican epoch, Gasteropods and Cephalopods are represented by many
species of several genera. From this great discrepancy it is natural
to conclude that the American Primordial period was continued on
in time beyond the European.
The Calciferous formation has an exact representative in Great Britain
in the Sutherland limestone of the Northwestern Highlands, among whose
fossils are species of Ophileta and others characteristic of the beds. The Calci¬
ferous beds of America are separated by some geologists abroad from the
Primordial or Potsdam period; but, as appears above, this is not sustained by
investigation.
Should it be proposed to divide the beds differently, and transfer the Dicello-
cephalus strata of the Upper Mississippi to the Calciferous, in order to remove
these Trilobites from the Potsdam,—or to transfer the lower limestone of the
Quebec group to the Potsdam, so as to place all the Dicelloccphali in the latter
(which would thus be done),—objections would be equally encountered. (1.) No
break in the strata sustains such a course; (2.) The Calciferous and Potsdam
TRENTON PERIOD.
205
epochs are still united by having several species in common, while no Calcife-
rous species pass into the Chazy; (3.) The genus Conocephalm, Primordial in
Europe, is well represented in the Calciferous; (4.) (lasteropods and Cephalo-
pods, not Primordial in Europe, are not by these means removed from the
Potsdam.
2. TRENTON PERIOD (3).
Epochs. — 1. Chazy (3 a), or epoch of the Chazy limestone.
2. Trenton (3 b), or epoch of the Birdseye, Black River, and
Trenton limestones.
I. Rocks : kinds and distribution.
1. American.
The Trenton period was characterized by a profusion of Brachio-
pods, Trilobites, and Orthocerata, and by the making of limestone
strata, almost of continental extent, out of the shells and other
calcareous relics of the living species. The rocks extend over a
large part of the continent east of the Mississippi, and beyond to¬
wards the Rocky Mountains.
The Chazy limestone (3 a), or that of the Chazy epoch, is so
named from the town of Chazy, in Clinton co., N.Y., on the west
side of Lake Champlain, where the formation occurs. The rock is
mostly a grayish limestone, and the fossils are remarkable for being,
with few exceptions, quite small.
The Trenton limestone (3 b) derives its name from the well-known
locality of the rock along the gorge at Trenton Falls in central New
York. The rock is gray to black in color, the dark colors predo¬
minating in New York, and the grayish in the West.
The thickness of the whole series in northern New York and
Canada, towards the Azoic, where probably lay the ocean's border,
is generally from 100 to 300 feet; yet in the region of Ottawa—a
great St. Lawrence Bay in the earlier Silurian era (see map p. 170,)
—it is about 800 feet. West of the Appalachians the thickness
averages about 300 feet. Along the Appalachian region, in Penn¬
sylvania, it is from 300 to 500 feet.
1. Chazy epoch.—(a.) Interior Continental basin.—The Chazy limestone
outcrops at different places in northern New York, in the vicinity of the Azoic
(though not along its more southern border); also in Canada, around the Trenton
limestone of the Ottawa basin, and from the head of Lake Ontario westward
to Lake Huron. The thickness in some parts of Now York is 100 to 150 feet.
Occasionally it graduates into the next rock below, the Calciferous sandrock, so
that the two are separated with difficulty. In the region of the Upper Missis¬
sippi, in Wisconsin, Minnesota, and Iowa, there is a sandstone called by Owen
St. Peter's sandstone, from a locality at the mouth of St. Peter's River. It
206
PALAEOZOIC TIME LOWER SILURIAN.
overlies the Calciferous, and underlies the Trenton: its relation to the Chazy,
beyond this of position, has not yet been determined.
The Chazy limestone has been stated to occur in Northern America, in the
Winnipeg region, west of the Azoic.
(b.) Appalachian region.—The Chazy has not been recognized along any
portion of the Green Mountains. It is supposed to be represented in the upper
part of the Quebec group. In Pennsylvania, there is a magnesian limestone,
5000 to 6000 feet thick in some places, corresponding to the Trenton period,
according to H. D. Rogers; but what part is Chazy is not yet ascertained.
(c.) Eastern border.—A limestone of the Chazy epoch occurs at the Mingan
Islands, in the Gulf of St. Lawrence.
(d.) Arctic region.—Limestone strata, containing Chazy fossils, have been ob¬
served in the Arctic, on King William's Island, North Devon, and at Depot
Bay in Bellot's Strait (lat. 72°, long. 94°). The species Ortlioceras moniliforme
Hall, and a Maclurca (31. Arctica Ilaughton) near 3d. magna, have been observed.
The limestone is in part a cream-colored dolomite.
2. Trenton epoch.—(a). Interior Continental basin.—In New York and
Canada, the Trenton limestone directly overlies the Chazy. The lower part in
New York is made up of the Birdseye and Black River limestones (the latter
the upper); and these same subdivisions have been distinguished in much of the
Mississippi basin.
The Birdseye limestone is so called from whitish crystalline points or spots
distributed through it. This peculiarity, however, is not always present, and
occurs in other limestones. The color is drab or dove-colored and brownish,
and not so dark as that of the overlying beds.
The Black River limestone is named from Black River, east of Lake Ontario,
in New York, along which there are the best exposures of it. The color is
generally dark, nearly black.
The Trenton limestone in New York is grayish-black to black. It is some¬
times bituminous, especially in its upper portions. Its layers are often thin, and
frequently argillaceous, and beds of shale in many places intervene. The black
color is due to carbon or bitumen, as is shown by its burning white.
The Trenton limestone has been recognized in the Winnipeg region in British
America, as well as over much of the Mississippi basin. The Galena or lead-
bearing limestone of Wisconsin and the adjoining States in the West constitutes
the upper portion of the Trenton series, and often alternates with layers of the
Trenton limestone.
The rock, though generally common limestone, sometimes includes layers of
magnesian limestone ; and the Galena beds are generally magnesian. (See ana¬
lysis on p. 84.)
The thickness in New York seldom exceeds 300 feet. At Montreal it is 600
feet (Logan) ; on the Manitoulin Islands, in the St. Lawrence, not over 300 feet;
in the Michigan peninsula, about 32 feet (Winchell); in the region more to the
west, usually about 300 feet; in middle Tennessee, where the beds are called
the Stones River group by Safford, 200 to 300 feet; in Missouri, 400 to 500 feet
(Swallow). In Iowa the Galena limestone is 250 feet near Dubuque, and the
Trenton 20 to 100 feet (Hall).
(b.) Appalachian region.—The limestones of the Trenton, epoch have great
TRENTON PERIOD.
207
thickness in Pennsylvania,—probably 2000 feet or more. In eastern Tennessee
the thickness is more than double that in the central basin of the State, being
at least 500 or 600 feet (Saft'ord).
(c.) Arctic region.—The Trenton limestone has been identified in the Arctic on
the west shore of King William's Island, at Fury Point on North Somerset, on
the east and west sides of Boothia. The Boothia rock is a dolomite, containing
carbonate of lime 54.92, carbonate of magnesia 42.57, clay and oxyd of iron
2.51.
3. Minerals.—The lead-mines of Wisconsin and the adjoining region are
situated in the Galena limestone,—a rock named from the mineralogical designa¬
tion of the common ore of lead, galena. The ore occurs in large irregular beds
or extended masses, sometimes spreading like veins, though not properly of this
nature. The lead-region of Wisconsin and Illinois, according to Owen, is 87
miles from east to west and 54 from north to south ; and throughout much of
this region traces of lead may be found. The beds resemble in position the
lead-mines of Missouri; but the latter occur in a limestone of the Calcifcrous
epoch. These mines of the Upper Mississippi have been the subject of a recent
report by J. D. Whitney.
2. European.
Rocks of the Trenton period occur in Great Britain and many
parts of Europe; and by their general distribution they show that
they have the same continental character as in North America.
In England, the rocks, instead of being limestones, are almost solely shales
and shaly sandstone (flags), with only thin beds of limestone. They include
the Llandeilo flags and shale, which are many thousand feet thick, succeeding
to which, as the following part in the series, are the Caradoc sandstone of
Shropshire and the Caradoc or Bala formation of Wales. The latter are sup¬
posed to represent the American Hudson period. Among the Bala beds are
some thin layers of limestone. The thickness of the Lower Silurian of Great
Britain above the base of the Llandeilo formation of Wales is estimated by
Murchison at 18,000 feet.
In Spain, also, there are schists and sandstones, with some limestones. In
Scandinavia there are limestones overlaid by slates and flags ; and in Russia
and the Baltic provinces, mainly limestones.
It thus appears that along the border regions of the European continent, as
in England and Spain and Scandinavia in part, the rocks are mainly sandy or
argillaceous, while over the interior, limestones abound.
I. Life.
1. American.
1. Plants.
Sea-weeds are the only fossil plants. Two of the species are
represented in figs. 262, 263.
208
PALAEOZOIC TIME LOWER SILURIAN.
Specimens of Sea-weeds are rare. Eig. 262 is the Biitliotrepliis gracilis, and
fig. 263, B. 8ucculo8us. The figures represent only portions of these plants.
Many fossil Sea-weeds are not to he looked for in limestones.
2. Animals.
The seas of the Trenton period were densely populated with
animal life. Many of the beds are made of the shells, corals, and
crinoids packed down in bulk ; and the less fossiliferous compact
kinds have probably the same origin, and differ only in that the
shells and other relics were pulverized by the action of the sea, and
reduced to a calcareous earth before consolidation.
With the Trenton period there appeared species of undoubted
Polyps, the true coral animals of the seas (fig. 277, etc.); and the
sub-kingdom of Radiates has hence all its three classes, Polyps,
Acalephs, and Echinoderms, represented. These corals belong
mostly to the Cyathophyllum family, and where they occurred they
gave the aspect of a flower-garden to the sea-bottom in shallow
waters. The Molluscan sub-kingdom included numbers of Con-
chifers and Bryozoans, as well as Brachiopods, Pteropods, Gastero-
pods, and Ceplialopods ; and all these divisions were wdll repre¬
sented. Both the Molluscan and Radiate sub-kingdoms were,
therefore, fully unfolded in all their grand types, though not ad¬
vanced to thb high rank they afterwards attained. In the sub-king¬
dom of Articulates there is no progress above Worms and Crus¬
taceans ; and no trace of a Fish or of any Vertebrate has been
found in the rocks of the period.
The prevailing types are—(1) Brachiopods (figs. 268-270, 286-300),
whose shells outnumber and outweigh all other remains together;
(2) Orthocerata (figs. 313-315), of the class of Ceplialopods, which
are numerous, and some of them ten to fifteen feet long and a foot
in diameter; (3) Crinoids (figs. 264, 284, 285), which rank next to
TRENTON PERIOD.
209
Brachiopocls in the profusion of their relics ; (4) Trilobites (figs. 320
-326), which are greatly multiplied in genera and numbers of
species, and attain in some cases a gigantic size; (5) Bryozoans, a
group including a multitude of delicate corals having minute cells
(figs. 266, 267).
There were but few Polyp-corals, compared with the number in
later periods. Single masses of the coral Columnaria alveolata H.
(fig. 278) occur in the Black River limestone, weighing between
two and three thousand pounds. Delicate, plume-like fossils, called
Graptolites (p. 190 and fig. 281), were a feature of the seas, though
still more common in the next, or Hudson, period. Cystids (figs.
265, 285) were the most characteristic kind of Crinoids. They
belong in geological history eminently to this early era, reaching in
it their greatest expansion. The Brachiopods were small species
in the first epoch (figs. 268-270), but large and of many kinds in the
following (figs. 286-300). The Trenton species were mostly of the
Orthis family (the genera Orthis, Orthisina, Leptccna, and Stropliomena);
and with these there were species of the Lingula, Discina, and Rhyn-
chonella groups,—the same families that were represented in the
earlier Calciferous epoch. The genera lihynchonella (fig. 270), which
begins in the Chazy, and Crania (fig. 330), of the Trenton, have
representatives in modern seas.
The small bivalve Crustaceans Leperditice, (fig. 276) occur in im¬
mense numbers in some places, as on the Ottawa in Canada, where
a bed of limestone two feet thick is wholly made up of them ; and
yet the length of the shell is only one-ninth of an inch.
The huge Orthocerata exceeded in magnitude any existing Cepha-
lopods, and were the great animals of the Trenton world,—the first
in size and rank.
Characteristic Species.—1. Chazy Epoch.
1. Protozoans—-Spongea.—Eospongia lioemeri and E. varians B. occur at
the Mingan Islands.
2. Radiates.—(«.) Polyps.—No species have been described. (6.) Aca-
lephs.—Species of Clixtetcs and Columnaria (Billings), (e.) Echinodenns.—The
Crinoids include as many known Cystids as Crinids. The following are a few
of them :—
(1.) Crinids.—Palreocrinus striatus Billings (fig. 264), the body, showing the
radiating ambulacral grooves (five) at top; Blastoidocrinus carcharidens B.,—
the genus apparently of the Pentremite family, a family which makes its next
appearance in the middle Devonian and abounds in the Subcarboniferous.—
(2.) Cystids:—Mtdocystis Murchisoni B. (fig. 265), the body nearly spherical
(whence the name, from the Latin malum, an apple), and having no arms, and
the ambulacral grooves irregularly radiating. Another Chazy genus is the
Palxocystis B., which includes Hall's Actinocrinm tenuiradiatus.
15
210
PALEOZOIC TIME LOWER SILURIAN.
3. Mollusks (a.) Bryozoans.—Fig. 206 represents the Retepora incept a,
u thin reticulate coral, the surface of which, magnified, is shown in fig. 206 a :
Figs. 264-276.
Radiates.—Fig. 264, Palmocrinus striates: 265, Malocystis Murcliisoni. Mollusks.—266,
Retepora incepta; 267, Ptilodictya fenestrata; 2C8, Orthis costalis: 269, Leptsena piicifera;
270, Rhynclionella plena; 271, Maclurea magna; 272, M. Logani (X 273, operculum
of same; 274, Scalit.es angulatus; 275, Bellerophon rotundatum. Articulates.—276, Le-
perditia Canadensis, var. nana.
fig. 267, Ptilodictya fenestrata, a .small branching species, covered with minute
cells, and fig. 267 a, the surface magnified.
(b.) Brachiopods.—Fig. 268, Orthis costalis II.; fig. 269, Leptsena piicifera H.;
L. incrassata H. ; fig. 270, Rhynchonella plena. H. (a side-view).
(c.) Conch if ers.—None have been described.
(d.) Gasteropods.—Fig. 271, Maclurea magna, which is very abundant and
sometimes has a diameter of eight inches ; fig. 272, Maclurea Logani, showing
the shell closed by its operculum; fig. 272, the operculum in side-view; fig. 274,
Scalites angulatus Con.; fig. 275, Bellerophon (Bucania) rotundatum.
(e.) Cephalopods.— Orthoceras recti-annulatum II.; O. tenuiseptum H., a large
species, with the septa thin and rather crowded.
4. Articulates—(a.) Trilohites.—Among the species there are Illcenus
Arcturus II.; 7. c rassicauda ? ; Asaph us nhtusus II.; Asaphus (Isotelus) gigas
(fig. 320). There are also species of Bathyurus and Arnpy.r in the Canada rocks.
TRENTON PERIOD.
211
(6.) Ostracoids, or Bivalve Crustaceans.—Fig. 276, Leperditia Canadensis (var.
nana) Jones.
2. Trenton Epoch.
1. Protozoans.—Sponges.—Astylospongia parvula B. occurs near Ottawa
City, Canada. Several other species of sponge have been described by Roemer
from the rocks of western Tennessee.
2. Radiates—(a.) Polyps.—True Polyp-corals (pages 162, 163) occur here.
Fig. 277 is the Petraia Corniculum, a coral of the Cyathophyllum family, from
Figs. 277-285.
Radiates.—Fig. 277, Petraia Corniculum; 278, a. Columnaria alveolata; 279, 280, Chajtetes
Lycoperdon; 281, a, Graptolitlms amplexicaulis; 282, Palfeaster matutina; 283, Tasniaster
spinosa: 284, Lecanoerinus elegans; 2S5. l'leurooystis filitextus.
the Trenton limestone. When alive it had probably a circle of tentacles and
a flower-like summit, resembling closely lig. 147, and it may have been richly
colored. Fig. 278, a fragment of the Columnaria alreolata H., characteristic of
the Black River limestone in New York, but occurring elsewhere in the Trenton
limestone,—a section of one of the columnar cells shows the tables or par¬
titions of the interior; fig. 278 a, top-view, showing the radiate cells ; fig. 279,
Chxtetes Lycoperdon of the Trenton, a solid coral of a conoidal form, having
a fibrous or fine columnar structure, as shown in the sectional view, fig. 280.
A branching fossil, characteristic of the Birdseye, and called Pliytopsis tubu-
losus II., is a coral of the genus Tetradium, having cells like fig. 338 a. The
chain-coral (genus Hahjsites, a species of which is shown in fig. 336) has occa-
212
PAL7E0Z0IC TIME ]
•LOWER SILURIAN.
sionally been seen in the limestones of the Trenton epoch, as in the Galena
limestone, and in Canada.
(6.) Acalephs.—Fig. 2S1 is the Graptolithus amplexicanlis H. of the Trenton,
and 281 a an enlarged view. Agassiz refers also to the Acalephs the genera
Chsetetes (fig. 279), Favosites, Columnaria (fig. 278), and the related corals having
the cells divided by horizontal partitions, as explained on p. 162.
(c.) Ecliinodcrms.—Fig. 282, the Star-fish Palseaster matutinn II. of the
Trenton; 2S3, Tseniaster spinosa B.; fig. 284, the Crinid Lecanocrinus elegans
Billings; fig. 285, the two-armed Cystid Pleurocystis filitextus B., of the
Trenton, in Ottawa, Canada. (The figure of this Cystid is reversed.)
The number of Cystids described by E. Billings from the Lower Silurian of
Canada is 21; making in all for this era in North America, thus far known, 22;
the Crinids of the same era amount to 50 species, and the Star-fishes to 11; 13 of
the Crinids and 8 of the Star-fishes are Trenton species.
Figs. 286-300.
Brachiopods—Figs. 286, 287, Orthis Lynx: 288, 0. occidentalis; 289, 0. testudinaria; 290,
O. tricenaria; 291, Leptama sericea; 292, Stropliomena (Leptama) rugosa; 293, Stroph.
alternata; 294,295, 296, Rliynchonella increbescens; 297, 298, Rhynclionella bisunula;
299, Obolus filosus; 300, Lingula quadrata.
3. Mollusks (a.) Bryozoans.—Species of Betepora and Ptilodietya (re¬
lated to figs. 266, 267) are common.
TRENTON PERIOD.
213
(b.) Ttrachiopoch.—Figs. 286, 287, Orthis Lynx ; 283, 0. occidental** ; 289, 0.
testudinaria Dal.; 290, 0. tricenaria Con.; 291, Lcptsena sericea Sow.; 292,
Stropthomena rugosa (formerly Leptxna depress**); 293, Stroph. alternata; 294—
296, lihynchonella tncrebescens II.; 297, 298, lihynchonella ? hisulcata.
(e.) Conchi/ers.—Fig. 301, Avicula ? Trentonensis Con.; 302, Ambonycliia belli-
striata II.; 303, Ctenodonta nasuta; also Conocardium immaturum B., of Black
River limestone on the Ottawa, Canada, and species of Modialopsis.
Figs. 301-303.
Conchifers.—Fig. 301, Avicula? Trentonensis; 302, Ambonycliia bellistriata; 303, Cteno¬
donta nasuta.
(d.) Gasteropods.—Fig. 304, Pleurotomaria lenticular*s Con., very common in
the Trenton limestone; 305, Murchisonia bicincta ; 306, M. bellicincta, often four
Inches long; 307, Helicotoma planulata Salter, from Canada; 308, Belleroplion
Figs. 304-312.
<1 asteropods."—Fig. 304, Pleurotomaria lenticularis; 305, Murchisonia bicincta; 30(5, M.
bellicincta; 307, Ilelicotoma planulata; 308,309, Belleroplion bilobatus; 310, Cyrtolites
compressus; 311, C. (?) Trentonensis , 312, id., dorsal view.
bilobatus, very common; 309, same, side-view; 310, Cyrtolites compressus II;
311, 312, Cyrtolites (?) Trentonensis. The genus Cyrtolites is like a partly-un¬
coiled Belleroplion, and is not chambered. There are also several Patella-like
species of lletoptoma (formerly Capulus and Patella), a genus which began in the
Calciferous beds.
(e.) Cephalopods.—Fig. 313, Orthoceras juncettm II, a small Trenton species;
314, O. vertebrate II., also Trenton, the figure reduced to one-third; 315, part
of an Ormoceras tenui'/Hum, showing the beaded siphuncle and septa. The spe¬
cies is very common in the Black River limestone, and is sometimes over two
214
PALAEOZOIC TIME LOWER SILURIAN.
feet long: the genus Ormoceras is peculiar in the beaded form of the siphuncle
Other common species of the Orthoceras family are the Endoccras protei/orme II.,
and the Gonioceras aneeps H. The Endoccras is the most gigantic known,
Figs 313-318.
Cephalopods.—Fig. 313, a, Orthoceras juncenm; 311, 0. vertebrate; 315, Ormoceras te-
nuifilum; 316, a, Cyrtoceras annulatum; 317, Cryptoceras uudatum; 318, Trocholites
Ammonius.
having attained a length in some cases of fifteen feet, and a diameter of nearly
one foot. In the genus Endoceras (from the Greek sspaj, horn, and tvbov, within)
there is a concentric structure of cone within cone. In the Gonioceras the septa
or partitions are very much crowded and have a double curvature, and the
siphuncle is central.
(_/.) There are also curved species. Fig. 316 is Cyrtoceras annulatum II. ;
a, a transverse section, showing the position of the siphuncle; fig. 317, Cryp¬
toceras undatnm (Lituites undata H.), an abundant species in the Black
River limestone; fig. 318, Trocholites Ammonius of the Trenton; 318 a, a
transverse section. In Cryptoceras the spire is open at the outer extremity and
the siphuncle is dorsal; while in Trocholites it is closed and very tightly coiled
throughout. Lituites, another genus of the period, which first appeared in the
Caleiferous, differs from Cryptoceras in having the siphuncle subcentral. The
genus Pliragmoceras is peculiar in having the mouth of the shell very much con¬
tracted by a bending inward of the sides. A species, P. iminaturuin B., occurs
in the Black River limestone of Canada.
TRENTON PERIOD.
215
Fig. 319 represents Conularia Trentonensis H., a delicate four-sided pyramid,
apparently admitting of some motion at the angles, but having septa within
in the smaller extremity (<?), and supposed therefore to be
the shell of a Cephalopod ; b is an enlarged view of the
surface.
4. Articulates (a.) Trilobites.—Fig. 320, Asaph us
(boletus) gigcts7 a small specimen; the species is sometimes
ten inches or a foot long; fig. 321, Calymenc senaria Con. ;
fig. 321 a, same rolled up, by bringing the tail to the head ;
fig. 322, Lichas Trentonensis; fig. 323, Trinucleus conceu-
tricus; figs. 324, 325, Agnostus lobatus, H., head and tail
portions magnified; 326, natural size.
(b.) Ostracoids.—Fig. 327, Leperditia Fabulites? Con.,
natural size; a, b, transverse and vertical sections, the
specimen from Canada (L. Josephiana Jones, who refers Conularia Trentonensis
the species with a query to the Fabulites of Conrad).
In the State of New York the Black River limestone is especially remarkable
for its great abundance of species of the Orthoceras family, among which are
Figs. 320-327.
Crustaceans.—Fig. 320, Asaplius gigas (X %)', 321, a, Calymene senaria; 322, Lichas Tren¬
tonensis; 323, Trinucleus concentricus; 324, 325, Agnostus lobatus (X 4); 326, same,
natural size; 327, a, b, Leperditia Fabulites (natural size).
the species Ormoceras tenuifilum H., Endoceras longissimum II., and Gonio-
ceras anceps, which do not recur in the overlying Trenton limestone. Some of
them are, however, found in rocks in Canada whose fossils are two-thirds those
of the Trenton; and both there and in Tennessee, as well as other parts of the
West, there is a mingling of Black River, Birdseye, and Trenton fossils, which
proves that the rocks make but one group. (Billings.)
The number of Chazy species occurring in the Trenton group has not been
recently announced.
Fig. 319.
216
PAL2E0Z0IC TIME LOWER SILURIAN
2. European.
The same subdivisions of the kingdoms of life are represented in Europe as
in America, the Radiate and Molluscan having their grander types brought out
in species, while the Articulates appear only as Worms and Crustaceans, with
Trilobitcs the predominant tribe. Moreover, the genera of Trilobites, Ortho-
cerata, Brachiopods, etc., are, in the main, the same; and many species have
been published as identical with American fossils. Among these species of
wide range there are the following:—The species Asaphus giyas, Trinucleus con-
centricns, Orthis striatula, Orthis Lynx, Strophomcna alternate!, Lcptx.ua sericen,
Mnrchiuonia bicincta, Bellerophon bilobatus, and others, occurring in the Llan-
deilo flags or their equivalents in Great Britain. Trinucleus concentricus is
also reported from Bohemia; Orthis Lynx (or biforata), 0. striatula, Belle¬
rophon bilobatus, from Russia and Scandinavia. The group of Cystids reached
a climax, as in America; the Bala limestone in Great Britain and equivalent
beds in Bohemia and Sweden containing the species in greatest abundance,
the number from these regions now known being over forty.
The annexed cut represents a few of the British species of the Llandeilo flags
and Bala limestone.
Fig. 328, Orthis Flabellidnm, one of the coarsely-plaited species of Orthis, and
fig. 329, 0. elcgantula, both stated to range from the Llandeilo into the Upper
Figs. 328-334.
Fig. 328, Orthis Flabellulum; 329, 0. elegantula; 330, Crania divaricata; 331, Conocardium
dipteruin ; 332, Asaphus Powisii; 333, IUaenus Davisii; 334, Ampyx nudus.
Silurian; fig. 330, Crania divaricata, the earliest species of the genus, adding
another to the number of genera that range from the Lower Silurian to the
present time; fig. 331, Conocardium dipterum of the Ayrshire beds; fig. 332,
Asaph us Powisii; fig. 333, Jllsenus Davisii Salter; fig. 334, Ampyx nudus, a tri-
lohite of the Llandeilo flags; fig. 177 (p. 151), Calymene Blumenbachii, which
includes the C. senaria of the Trenton, reported to range from the Bala lime¬
stone into the Wenlock of the Upper Silurian.
The earliest Rhizopods (see p. 163) yet discovered have been found byEhren-
berg in the Obolus or Ungulite grit of Russia. The rock is in part a very soft
green-sand; and the connection of the microscopic Rhizopod shells with the
green grains shows, as Ehrenberg states, that it is of the same nature with the
Green-sand of the Cretaceous. Among these fossils occur the three modern
HUDSON PERIOD.
217
genera Textularia, Ratal ia, and Guttulina. Ehrenberg has also detected in this
rook great numbers of Pteropods (related to Theca), and made out ten new spe-
ties and four genera. The rook derives its name from its most common fossil,
Obulus Apollinis (fig. 236), which is about as large as a small finger-nail. The
Siplionotreta unguicidata (fig. 235) is another of its fossils. The age of the beds
is either that of the Trenton or earlier.
;i. HUDSON PERIOD (4).
Epochs.—1. Utica, represented by the Utica shale (4 a); 2. Hud¬
son River, or that of the Hudson River shale and some contempo¬
raneous limestones (4 b).
In contrast with the Trenton period, the Hudson was pre-emi¬
nently a time of shale-making. Its surface-exposures in New York
State are shown on the map, the region being that marked 4. Its
life was abundant, and much resembled that of the Trenton period.
I. Rocks: kinds and distribution.
The Utica shale is the surface-rock along a narrow region in the
Mohawk valley, N.Y. (see 4 a on map, p. 170), following a course
nearly parallel with the outlineof the Azoic farther north. The shale
is in some places three hundred feet, or more, thick. It extends
westward through Canada, and beyond, probably, into Wisconsin
and Iowa, though a very thin deposit at the West. Along the
Appalachians it occurs in Pennsylvania, and is from three hundred
to seven hundred feet thick.
The rock is a crumbling shale, mostly of a dark blue-black or
brownish-black color, and frequently bituminous or carbonaceous,
—so much so as in certain places to serve as a black pigment. It
sometimes contains thin coaly seams; and much money has been
foolishly spent in searching for coal in this deposit. Thin layers
of limestone are occasionally interpolated, especially in the lower
part.
The Hudson River shales are exposed to view through the centre of
New York, near the Mohawk, and westward from the northwestern
side of Lake Ontario across Canada (following the course in New
York) to Lake Huron (see map, fig. 205); also farther west, in Michi¬
gan, Wisconsin, and Iowa. The rocks are slates or crumbling shales,
with some flagging-stone, in New York; but westward they become
more or less calcareous.
The formation is represented ii> southern Ohio, about Cincinnati,
by a thick limestone, called " Blue Limestone," but the beds are
much interlaminated with a soft shale or marl; and this same rock
218
PALAEOZOIC TIME LOWER SILURIAN.
stretches across the Ohio into Kentucky and Tennessee, and west¬
ward into Illinois and Missouri. The greatest thickness in New
York is nearly 1000 feet; in the Northwest it is very thin. Along
the Appalachian region, in Pennsylvania, the rock is a shale, and
has a thickness of 1000 feet or more.
In the Eastern border, at the island of Antieosti, the lower
part of a limestone formation has been referred to this period;
but recent investigations discredit it.
1. Utica Epoch.—(a.) Interior Continental basin.—The Utica shale is 15
to 35 feet thick at Glenn's Falls, in New York; 250 feet in Montgomery co.; 300
in Lewis co.
(6.) Appalachian region.—In Pennsylvania, the rock is a black shale, and in
some parts it is fossiliferous. The thickness given by Professor Rogers in the
Kittatinny, Nippenose, and Nittany valleys is 300 feet, and in the Kischico-
quillas valley 400 feet.
2. Hudson River Epoch.—(a.) Interior Continental basin.—The Hudson
River shales cover the region north of Lake Champlain, in Canada, west of the
great fault which marks the western boundary of the Calciferous beds (see map,
fig. 205), and they also lie over a small area near the centre of the Trenton
limestone region of the Ottawa basin.
The thickness of the shales in Schoharie co., N.Y., is 700 feet (Yanuxem);
on Lake Huron, 180 feet (Logan); in the Michigan peninsula, 18 feet (Win-
chell); in Iowa, 25 to 100 feet (Hall A Whitney). In Missouri, there are alter¬
nating strata of shale and limestone, 20 feet and less to 60 feet thick, the whole
120 feet in thickness (Swallow). In,central Tennessee, the beds constitute
part of the Nashville group of Safford (the lower part being Trenton), and
consist of argillaceous limestone with many shaly layers: they are a few
hundred feet thick.
(b.) Appalachian region.—In Pennsylvania, in the Kishicoquillas valley, the
rock is a blue shale and slate, with some thin layers of calcareous sandstone,
and the thickness is 1200 feet; in the Nittany valley, 700 feet; in the Nippe¬
nose valley, a little less. (Rogers.) In eastern Tennessee, the beds (corre¬
sponding to both the Utica and Hudson River epochs) are of great extent, and
consist of calcareous and more or less sandy shales, abounding at times in
Graptolitcs, with some thin layers of calcareous sandstone. They also occur
of great thickness in Virginia, and reach down to Alabama.
(e.) Eastern border.—The limestone formation of the island of Antieosti, re¬
ferred to the Hudson period, has a thickness of nearly 1000 feet. The limestone
is often impure, and is interstratified to some extent with shales. The strata are
nearly horizontal.
3. Minerals.—In the Utica shale, near Spraker's Basin, there is
some lead-ore (galena) in small veins occupying the joints of the
rock. Mr. Whitney has called attention to the large amount of
carbon in the Hudson River shales from New York to Iowa, and
its economical importance. In the rock near Savannah, Illinois,
HUDSON PERIOD.
219
he found the combustible portion amounting to 20.96, or about
21 pounds to every 100 of the shale; in that of Dubuque, 11 to
16 per cent.; in that of Herkimer co., N.Y. (Utica shale), 12 to 14
per cent.
The springs of Saratoga and Ballston rise from the lower part
of the Hudson River shales.
II. Life.
The larger part of the species found in the American rocks
of the Hudson period are identical with those of the Trenton,
—although a considerable number are still peculiar to the period.
The Utica shale, like most fine soft shales, contains few fossils,—the
conditions of the formation having been such, apparently, as re¬
sulted in their complete trituration and destruction. The Hudson
River beds, while partly as fine as the Utica shale, are often a little
coarser in texture, as if formed of the kind of mud that abounds
at moderate depths in marine life ; and these somewhat sandy
beds, as well as the limestones, are especially fossiliferous. The
species in the limestones are often identical with those of the
Trenton period,—a limestone period; while those of the shales are
mostly different. The latter are, for the most part, those that live
where the bottom is muddy; while the species whose relics make
the limestones require clear waters, and flourish, like the shells
of the coral seas, upon the submerged limestone reef which is in
process of formation.
Plants.
The plants observed are all Sea-weeds, or Fucoids.
The great amount of carbonaceous material in the shales was
probably derived mostly from these plants: it may have partly
come from animal life.
Animals.
Where the rocks are sandy or shaly, there are few corals or
Trilobites; and these Hudson River beds in New York are, hence,
in strong contrast with those of the Trenton period. At the
same time, Conchifers are much more numerous. This is the kind
of difference that exists now between the species of a muddy
bottom and those of a clear, coral-growing sea.
A striking feature of the shales is the abundance of Graptolites.
They occur in the shales of Tennessee and the Upper Mississippi,
as well as those of New York. These feathery species must have
220
PALAEOZOIC TIME LOWER SILURIAN.
grown thickly over the muddy sea-bottom ; for the thinnest layers
of the slates are sometimes crowdedly covered with their delicate
tracery. In the limestone regions of the period, as about Cincin¬
nati, corals and Trilobites are common, and one species of the
latter, related to the Isotelus of Trenton Falls,—the Asaphus (Iso-
tclus) megistos,—was twenty inches long and a foot broad.
Characteristic Species.
1. Radiates.—(a.) Polyps.—No corals have been described from the Utica
shale. In the Hudson River beds in New York there are species of Chxtetes
related to those of the Trenton, and rarely specimens of the Favistella slellata II.
(fig. 335), a columniforin coral related to the Favosites, having stellate cells.
This species is more abundant in the West. But few of the corals of the Hud¬
son River epoch from Ohio and the States beyond have been described.
Cyathophylla of the genus Petraia occur, as in the Trenton; also a species
of the Chain-coral, or Ilalysitcs (/:/. gracilis H., fig. 336, from Green Bay,
Wisconsin); also Syringopora obsoleta II. (fig. 337); and species of the genus
Tetradium, as Tetradium Jibrosum, fig. 338, a.
Figs. 335-339.
Fig. 335, Favistella stellata; 330, Ilalysitcs gracilis: 337, Syringopora obsoleta; 338, c,
Tetradium fibrosum; 339, Glyptocrinus decadactylus.
(b.) Acalephs.—Fig. 251 (page 191) represents the Graptolithus prist is II., a
species occurring abundantly in the Hudson River and Utica shales at many
localities. Several other species have been described by Hall.
(c.) Echinoderms.—Crinids, Oystids, and Star-fishes occur in the rocks of the
period. Among Crinids, the Glyptocrinus decadactylus H. (fig. 339) is not un¬
common, occurring in New York, Ohio, Kentucky, and other States. Fig.
349 represents a large Star-fish from the Blue limestone of Cincinnati, as figured
by U. P. James, the original of which was four inches across.
2. Mollusks.—The Trenton Brachiopods LepUrna scricea, fig. 291; Stro-
phomena alternata, fig. 293; Orthis testudinaria, fig. 289; Orthis Lynx, fig. 280;
Orthis occidental is, fig. 288; Rhijnchonclla incrcbcsccns, figs. 294-290; and some
others, arc continued in the Hudson River period: also the Gasteropods Belle-
HUDSON PERIOD.
221
rophon bilabatua, figs. 308, 309; Trooholites Ammonias, fig. 318; and some
Ceplialopods of the Orthoceras family, etc. There are also in the rocks of this
Fig. 349.
Echinodf.rm.—Palasterina (?) Jamesii.
period, and characteristic of them, the Conchifers Avicula demissa, fig, 350;
Ambonychia radiata, fig. 351; Modiolopsis modiolaris, fig. 352; Orthonota paral-
Conchifers.—Fig. 350, Avicula demissa; 351, Ambonychia radiata; 352, Modiolopsis
modiolaris (X %); 353, Orthonota parallela.
lela H., fig. 353. Among the Gasteropods occurs the Cyrtolites ornutus, near
fig. 310.
222 PALAEOZOIC TIME LOWER SILURIAN.
3. Articulates.—Among Trilobites, the Aaaphus (Isotelus) giijas, and Trinn-
e/ei<s concentricity, continue on from the Trenton period ; but the A.gitjas is rivalled
both as to abundance and size by the A. mc/jivtos, already referred to, found in
Ohio and other States west. The Triartlirus Beckii is common in the Utica
shale, and occasionally seen in the Trenton beds. The head-shield generally
occurs without the body : fig. 354 represents its usual form, and fig. 355 the
same entire. The body is much like that of a Calymcne (fig. 321): it has a row
of minute spines along the middle of the back.
III. General Observations on the Trenton and Hudson Periods.
Geography.—The Trenton and Hudson periods stand apart less
through a difference of fauna than a geographical change which
caused, over large areas, shales to succeed limestones. Were the
life alone considered, they might well be united in one period.
Since the Trenton limestones extend widely over the continent
and are full of marine fossils, the land must have been covered as
widely by the sea. The beds reach nearly to the Azoic on the
north, and hence the coast-line from New York westward was
situated but little south of its position in the Azoic period. (See
maps, pp. 136, 170.) And it is probable, from the occurrence of
the rocks in the Winnipeg basin, that this line, bending northward
near Lake Superior, followed the western border of the Azoic
towards the Arctic.
The general absence of shales, even along the northern border
as well as the Appalachian region, can be accounted for only on
the supposition that the ocean had not free access from the east¬
ward over the continent. The interior was probably in the condition
of the lagoon or inner basin of a coral island. A barrier produced
by the slight emergence of some part of the Atlantic border
would have caused such a condition of the continent; and less
than ten feet of elevation would have been sufficient,—for no more
is needed in the islands of the Pacific. Its breadth may have varied
from scores of miles to only a few rods. To the south, the waters
probably opened (as they did afterwards) into the Gulf of Mexico:
a connection with the ocean was necessary for their purity.
••TRENTON AND HUDSON PERIODS. 223
It is possible that this barrier, or reef, extended along the present
position of the Green Mountains ; but to the south, in Pennsyl¬
vania and Virginia, it must have lain to the eastward of the Appala¬
chian region, since the Trenton rocks in part constitute that por¬
tion of the chain. The depth of water may have been small, if we
judge from what is necessary for the formation of such limestones
at the present clay. Any subsidence in progress during its forma¬
tion must have been exceedingly slow,—less than half an inch a
year; for otherwise the animals forming the limestones out of
their shells would have been destroyed by being sunk below the
depth at which they could live. There was, beyond doubt, such a
slowly-progressing subsidence; and in the Appalachians it ex¬
ceeded in the end near G000 feet (the thickness of the Trenton
limestones), while over the interior it was, in general, not far from
300 feet.
The great St. Lawrence bay about Ottawa still existed, as in the
Potsdam period, though probably somewhat contracted in size.
(Map, fig. 205.) Here the subsidence must have been nearly 1000 feet.
The thin layers of shale in the Trenton limestone are no more
than would have naturally been formed by streams flowing from
the northern Azoic.
But with the opening of the Hudson period shales were formed
in Canada and from the Hudson River westward along the northern
border of the United States. They have their greatest thickness
to the eastward, where they extend from Canada and New York
southwest, along the Appalachian region; but over the middle of
the interior basin, limestones (though often somewhat mixed with
shales) were still in progress. It is evident that some great change
had taken place. Probably the subsidence along the northern
border of the United States (south of the Canada Azoic), and also
along the Appalachian region, had been increased in rapidity, until
the forming limestone reefs were submerged and the animals about
them destroyed,—thus putting an encl to the further increase of
the calcareous beds, and leaving them as the foundation for future
deposits. (A subsidence of the coral islands of the Pacific of 300
feet would wholly extinguish the life of the reef-forming corals.)
The eastern continental barrier may also have been partly siib-
merged, so as to admit the tidal and great oceanic currents, while
other parts of it were just washed by the waves which swept from
it and bore westward the finer detritus for portions of the Hudson
River shales. Had the waves of the ocean entered in full force,
beds of pebbles would have been more common among the de¬
posits. Wherever the layers are somewhat arenaceous and full of
224
PALAEOZOIC TIME LOWER SILURIAN.
unbroken fossils, there may have been shallow waters and a muddy
bottom, as with existing oyster-banks ; where there are tine shales
with few fossils, or a profusion of Graptolites, the depth was pro¬
bably somewhat greater,—for currents carry fine material farthest
fronf the shore-line; or there may have been sheltered bays, where
gentle trituration would have produced the finest silt.
The Hudson River shales crossing New York east of Lake Ontario,
and those of Canada west of this lake, follow so exactly the same
course that we conclude with reason that the depression of the
lake had not then been formed.
Over the interior of the Mississippi basin, away from the sub¬
siding regions, the Trenton condition of the seas may, for the most
part, have continued ; and hence the continuation there of the
limestone formations through the Hudson period.
The limestones of Anticosti Island, in the Gulf of St. Lawrence,
afford definite proof of an eastern geological basin or area, as Logan
has remarked. We have already spoken of this area (including
St. Lawrence bay and the region southwest, with part of New
England) as having to a great extent an independent geological
history ; and we shall soon have occasion to allude to it again. It
will be observed that the limestones of Anticosti, if of the Hudson
period, were in progress while the Hudson River shales were depo¬
siting over a considerable part of the United States.
As in the Potsdam period, the deposits of limestones and shales
had their greatest thickness along the Appalachian region. The
region, therefore, must have continued to be one undergoing great
changes of level, in which the amount of subsidence was very
large.
Climate.—No proof that a diversity of zones of climate prevailed
over the globe is observable in the fossils of the Trenton or Hudson
period, or of any part of the Lower Silurian era, as far as yet
studied. The following species, common in the United States, and
occurring at least as far south as Tennessee and Alabama, have been
found in the strata of northern North America, near Lake Winni¬
peg:—Strophomena altcrnata, Lcptccna sericea?, Maclurea magna, Pleuro-
tomaria lenticularis ?, Calymene senaria, Chcctetes Lycoperdon, Heceptaculites
Ncptuni.
The mild temperature of the Arctic is further evident from the
occurrence of the following United States and Eurojiean species at
the localities mentioned on page 207:—Chcctetes Lycoperdon, Orthoceras
moniliforme H., Heceptaculites Neptuni De France, Ormoceras crehriseptim
H., Huronia vertebralis Stokes ; besides Maclurea Arctica Haughton,
near the Chazy species M. magna. Moreover, the formation of thick
TRENTON AND HUDSON PERIODS-
225
strata of limestone shows that life like that of lower latitudes not
only existed there, but flourished in tropical profusion.
Life.—Exterminations. — The Chazy epoch, the commencement
of the Trenton period, opened with a new fauna, wholly dis¬
tinct in species from that which preceded it. At its close these
species, with few exceptions, disappear, and the Trenton epoch
begins with an independent life. No facts have been observed to
explain the nature of the catastrophe that intervenes between the
two epochs. Such a fact as this—that sinking the coral islands of
the Pacific three hundred feet would destroy the reef-forming Corals
of those islands—may have some bearing on the subject. The geo¬
graphical changes introducing the Hudson period appear to have
had some connection with the partial destruction of the Trenton
species that then occurred. A large number of species are conti¬
nued on from the Trenton into the Hudson period wherever the
rocks of the latter, like those of the former, are limestones. But
where the latter are shales,—that is, wherever the great geogra¬
phical change alluded to took place, which we have suggested may
have been a subsidence destructive to the life,—there the species
were almost wholly changed, and a new fauna appeared, and one
fitted for the muddy bottom, and, therefore, including many Con-
chifers with the Brachiopods, and but few Crinoids.
With the close of the Hudson period there was nearly a total
extinction of all the existing species throughout the great interior
continental basin and the Appalachian region. Not over eight or
ten species are known to have survived through the changes that
followed introductory to the Upper Silurian. In the eastern
border basin, at Anticosti, a much larger number of species conti¬
nued on,—at least thirty; and there, as is explained beyond, lime¬
stones still had uninterrupted progress, while fragmental rocks
spread largely over the rest of the continent.
The number of Lower Silurian species that are known to have
become extinct in the American seas from the beginning of the
Potsdam to the end of the Hudson period is about 850; and,
adding 400 for undescribed species (which is not too large an addi¬
tion), the whole number will be about 1250. (Billings.)
Many genera also disappeared in this time; and some of them
are enumerated in connection with the observations on the Pots¬
dam period. Among Mollusks, the genus Maclurea, containing
large species, is one of the most prominent. But, besides genera,
a whole family, in the case of the Graptolites, approaches its extinc¬
tion. These species have their commencement and culmination in
the Lower Silurian. Nearly all the genera of Cystideans also become
16
226
PALAEOZOIC TIME—LOWER SILURIAN.
extinct. This singular type of Crinoids had its climax in the
Lower Silurian, though not its final extinction. After this its
species were few ; while there is a great increase of Crinideans.
The number of Lower Silurian species known to have become
extinct in Great Britain is about 600, and in Bohemia, according to
Barrande, 300.
Thus far in American Geology, no evidence has been detected
of (1) fresh-water lakes or deposits, or (2) of land or fresh-water
life. The living species had been mainly Molluscan and Radiate,
because these are the water-types in the Animal kingdom. And
with them were associated the water-divisions of Articulates,—
Worms and Crustaceans; but not yet the water-division of
Vertebrates,—Fishes. The world had been populated solely by
Radiates, Mollusks, and Water-articulates. The continent was,
like its species, submarine in its mode of existence. It was already
outlined, and in its heavings and progressing changes its coming
features were shadowed forth,—even the Appalachian chain, and
the great lakes,—although the mountains had not yet a foot of
their present height above the seas, nor the lakes more than the
beginnings of their depressions.
DISTURBANCES CLOSING THE LOWER SILURIAN ERA.
The strata of the Lower Silurian in North America appear to
have been spread out over the Interior Continental basin in hori¬
zontal beds of great extent, and to have followed one another
without much disturbance of the formations,—that is, no upturn¬
ing that exposed outcropping edges to be overlaid by later hori¬
zontal deposits, producing thereby unconformability. In the Potsdam
period there were local eruptions of trap in the region of Lake
Superior; but no positive evidence of dislocations during the
Lower Silurian era is yet known. The period that witnessed the
gradual accumulation along the Appalachian region of 15,000 feet
of deposits, we are sure, was long; and the more remarkable, there¬
fore, is this exemption from catastrophe. Yet there is no doubt of
extended oscillations in the water-level over the continental area.
The rocks have afforded clear evidence of an indefinite range of
shallow waters and sand-flats throughout the great interior in the
Potsdam period ; of somewhat deeper waters over the same wide
area in the Trenton period, and such a uniformity of moderate
depth as admitted of the formation of limestones of continental
extent; then of other changes of level in the Hudson period,
LOWER SILURIAN.
227
which made shales, fine and coarse, to succeed, and alternate in
the interior with other limestones. But the changes of level in
these oscillations, although so great along the Appalachian region,
were but gentle movements in the thin crust of the globe ; and
they may have been partly oceanic as well as continental; for the
water-level along the continents would sink whether there were a
downward movement or sinking in the bed of the ocean, or an
upward bending of the land. But after the Hudson period there
were greater changes, attended with violence; and the rocks and
country bear marks of that violence,—probably more than have
yet been distinguished.
In British America, near Gaspe, on the Bay of St. Lawrence,
according to Logan, the Lower Silurian lies in tilted strata beneath
beds of the Upper Silurian,—showing that an upturning had oc¬
curred before these superior beds were formed. Similar facts have
been observed at the eastern base of the Green Mountains, where
limestones of Upper Silurian and Devonian age rest uneonform-
ably on the altered strata of the Quebec group ; and at Montreal,
where the Lower Ilelderberg overlies unconformably the Hudson
beds. The origin of the Champlain valley has been referred by
Logan to the epoch closing the Lower Silurian.
The following section (fig. 356) has been published by Logan, in illustration
of the fault, in the Appalachian series, in the vicinity of the Falls of Mont¬
morency, just east of Quebec. It extends from the Montmorency side of the
St. Lawrence across the north channel and the upper end of the island of
Orleans.
Fig. 356.
1 F 3 4 a 4 b 4 a 4 a 2
F is the fault; 1, Azoic gneiss (Laurentian of Logan); 3, Trenton limestone
overlying the Azoic; 4«, Utica shale, and 4 5, Hudson River shale; 2, the Que¬
bec group; S, S, the level of the sea; M, the position of Montmorency; C, the
North Channel; 0, Orleans Island. The horizontal and vertical scale is one
inch to a mile. " The channel of the Montmorency is cut through the black
beds of the Trenton formation to the Laurentian gneiss on which they rest,
and the water, at and below the bridge, flows down and across the gneiss, and
leaps at one bound to the foot of the precipice, which immediately behind the
water is composed of this rock." The Trenton limestone at the top of the pre¬
cipice is fifty feet thick and nearly horizontal; at the foot of the precipice it
lies against the gneiss of nearly the same thickness, but dipping at an angle
of 57°, and is overlaid by shales with some sandstone of the Utica formation.
228
PALAEOZOIC TIME—LOWER SILURIAN.
The Quebec group (Calciferous epoch) and the beds of the Trenton and Hudson
periods are represented as having been originally laid down in conformable
strata, and as having been involved together in the folding and faulting here
illustrated.*
In Pennsylvania, also, according to H. D. Rogers, the Upper Silurian beds of
the Kittatinny Mountain lie unconformably on the upturned Lower Silurian.
In Tennessee, according to J. M. Safford, there is an area some eighty miles
in diameter, about the centre of the State, which was probably raised above the
ocean at this same epoch; for, first, the next bed of rock covering it is a shale
of the Upper Devonian, the Upper Silurian and all the Lower Devonian being
absent; and, secondly, the absent rocks, where they appear around the area,
thin out towards it, while there is no evidence that denudation was the cause.
In Ohio, about Cincinnati, there is a large region where the Lower Silurian
strata are surface-rocks, owing to an uplift; but it is not yet known whether this
exposure was a consequence of a disturbance immediately after the formation
of the beds, or whether there were subsequent Silurian and Devonian beds which
have been removed by denudation.
Besides these changes, there was also a general increase of dry
land along the northern border of the United States and through
Canada. The broad band of Hudson River shales shown on the
map (p. 170) must have been left to a great extent exposed by an
uplift; for the next deposits do not cover it, and it is not probable
that they ever did. The dry land of the continent was gradually
expanding southward, and at the commencement of the Upper
Silurian its outline in New York lay to a considerable distance
south of the Mohawk River.
Moreover, the great St. Lawrence gulf about Ottawa, where the
Trenton and Hudson formations had been accumulated, was pro¬
bably nearly obliterated at this time; for no rocks of more recent
date occur there, to prove the presence of the sea, until the Post-
tertiary period, just before the Age of Man, excepting the small
patch of Lower Helderberg near Montreal. This region of dry
land spread eastward from Montreal to the Appalachian region
in Vermont, which region also was probably above the water-leveL
Thus, the St. Lawrence channel, which was first a short strait
between the Azoic areas of Canada and New York, had become
much narrowed and lengthened by the close of the Lower Silu¬
rian ; but it still opened into a broad oceanic basin near the
longitude of Quebec; for both Upper Silurian and Devonian strata
were formed over eastern Canada and a large part of New
* These facts and citations are from the paper of Sir William Logan, pub¬
lished in the Canadian Naturalist and Geologist, 1861, and also the Amer. Jour.
Sci. [2], xxxiii.
PALAEOZOIC TIME.
229
England. The eastern half of Vermont, as the rocks show, lay
within the submerged area; and hence the emergence of the
western (or Appalachian) portion had been small. Lake Champlain
was probably defined as a long, narrow bay or arm of the St.
Lawrence sea.
The disturbances opening the era of the Upper Silurian were
followed, if not attended, by the formation of a coarse conglome¬
rate along the Appalachian region, which is described beyond.
There was also, as has been remarked, a nearly complete extermi¬
nation of the living species over the continent.
In Europe there was also a period of disturbance at the close of
the Lower Silurian ; but the destruction of life was less complete
than over central North America, and corresponds nearly with
that in the eastern basin about the Gulf of St. Lawrence.
There is evidence of unconformability between the Upper and
Lower Silurian in some parts of England, and the elevation of the
Westmoreland Hills, as first ascertained by Professor Sedgwick, has
been referred to this epoch; so, also, that of the mountains in North
Wales, and hills in Cornwall, and the range of southern Scotland
from St. Abb's Head, on the east coast, to the Mull of Galloway.
Elie de Beaumont refers to this era the elevation of the Hundsruck
Chain (now about 3000 feet high) and other ridges in Nassau. The
changes of the period are supposed to have been attended in
England by metamorphic action, in which gneiss and clay slates
were made out of the Lower Silurian deposits by some process
dependent probably in part upon the escaping heat of the epoch
of disturbance.
B. UPPER SILURIAN.
Marine life, large oceans, small lands, and warm climates the
features of the Lower Silurian—continued to characterize the open
ing period of the Upper Silurian.
The periods and epochs indicated in the New York rocks have
been mentioned on p. 1G8. The periods are—the Niagara (5), the
Salina (G), and the Lower IIelderberg (7).
1. NIAGARA PERIOD (5).
Epochs.—1. Oneida epoch, or the epoch of transition between
the Lower and Upper Silurian, when the Oneida conglomerate (5 a)
was formed; 2. Medina epoch, or that of the Medina sandstone
230
PALAEOZOIC TIME UPPER SILURIAN-
(5 b); 3. Clinton epoch, or that of the Clinton group (5 c); 4.
Niagara epoch, or that of the Niagara shale and limestone (5 d).
1. ONEIDA EPOCH (5 a).
I. Rocks: kinds and distribution.
In the Interior Continental basin there are no Oneida rocks, except
in its northeastern corner. The Oneida conglomerate (5 a, map,
p. 170) is the surface-rock in central New York, in Oneida and
Oswego counties, and west to Lake Ontario, lying just south of the
outcropping Hudson River beds. It is 20 to 120 feet thick in this
region. Going eastward, it disappears, being very thin in Herkimer
co., and not occurring at all in the Helderberg Mountains south of
Albany. In the Appalachian region it has great thickness. In the
Shawangunk Mountains, in southeastern New York (which are
within this region), the rock is nearly 500 feet thick, and is called
the Shawangunk grit. It is still thicker to the southwest, in
Pennsylvania, being 700 feet thick in the Kittatinny valley.
It continues on through Virginia, following the course of the
Appalachians.
The rock is a hard, gritty conglomerate or sandstone, of a grayish
color, made of rounded quartz pebbles and sand, or of coarse sand
alone, very firmly cemented. It is so rough in surface as to serve
for millstones : the Esopus millstones are made of it. The firm¬
ness of the rock contrasts strikingly with the loose texture of the
Medina sandstones.
In the Eastern border region, at Anticosti, there are no signs of the
Oneida conglomerate; but, instead, the limestones referred to the
Hudson period are followed uninterruptedly by other limestones,
which are continued even into the Clinton epoch ; and in this
case the Oneida epoch has probably some representation among
the beds. But it is more probable, according to recent investiga¬
tions, that these limestones are wholly Upper Silurian, and belong
to the following epochs of the Niagara period.
In the Shawangunk Mountains there are two systems of joints, trending
S. 20° W. and S. 60° E. (Mather). The Ulster lead and copper mine near
Redbridge is situated in this rock: it has afforded large masses of galena and
copper pyrites, with blende, but is not worked. The Ellenville and Shawangunk
mines are others of similar character in the grit.
II. Life.
The only known fossils are Fucoids (Sea-weeds) and a few im¬
perfect, undetermined shells. One of the Fucoids resembles the
NIAGARA PERIOD—MEDINA EPOCH.
231
Fucoides (Arlhrophycus) Harlani, fig. 358,—a very common fossil in the
Medina sandstone. It suffices to prove that the Oneida epoch is
more closely related to that following than to the preceding, and
hence belongs to the Upper Silurian era.
2. MEDINA EPOCH (5 b).
I. Rocks : kinds and distribution.
In the Interior Continental basin the Medina formation is not known,
excepting to the northeast. It occurs in western New York, over¬
lying the Oneida conglomerate; towards Utica it thins out, and is
not known east of there. On the Niagara the beds have a thick¬
ness of 350 to 400 feet. It spreads northwest, and has been recog¬
nized as far as the Straits of Mackinac.
Along the Appalachian region it extends south through Penn¬
sylvania and Virginia, where in some places the beds are over 15C0
feet thick.
The rocks are argillaceous sandstones, and marls of red, gray, and
mottled colors. The sandstones are thinly laminated, as is usual
when much argillaceous, and in general are quite fragile.
In the Eastern border region, at the island of Anticosti, just north of
NovaScotia, limestones follow those referred to the Hudson period,
without interruption; the strata, according to the description in
Logan's Canadian Report, have a thickness—reckoning from the top
of the beds of the Hudson period, up to those which are regarded of
the Clinton epoch which follows the Medina—of 700 feet; they are
said to contain about thirty species of fossils common to the Lower
and Upper Silurian, and are described as beds of passage between
the two eras; but according to Shaler, all the beds of the lime¬
stone formation are Upper Silurian.
The relation of the Medina group to
the overlying Clinton and Niagara
groups is well illustrated in one or two
sections from the western part of the
State of New York. Fig. 357 repre¬
sents the rocks at Genesee Falls, near
Rochester. The lower strata, 1, 2, are
the Medina sandstone (5 5); 3, 4, 5, 6,
the Clinton group (5c); and 7, 8, the
Niagara group (5 d),—2 being a grit rock, 3 and 5 shales, 4 and 6 limestone, 7
shale, and 8 limestone. The whole height is about 400 feet.
The following figure (357 A) represents a section of the rocks along Niagara
River, from the bluff at Lewiston (L) to the Falls at F, passing by the Whirlpool
at W,—a distance of seven miles.
Fig. 357.
282
PALAEOZOIC TIME UPPER SILURIAN.
In the beds at Lewiston there are eight strata: 1, 2, 3, 4, belong to the Medina
group, and consist—1 and 3, of shaly sandstone; 2 and 4, of hard sandstone; 5, a
shale, and 6, limestone, are of the Clinton group ; 7, a shale, and 8, limestone, of
Fig. 357 A.
the Niagara group. The dip is up-stream, as in the figure, but is only fifteen
feet to a mile.
Where fullest developed in New York, the Medina group includes four divi¬
sions, as follow :—
4. Red marl or shale, and shaly sandstone, resembling No. 2, below; banded,
and spotted with red and green.
3. Flagstone,—a gray, laminated quartzose sandstone, called " gray band."
2. Argillaceous sandstone and shale, red, or mottled with red and gray.
1. Argillaceous sandstone, graduating below into the Oneida conglomerate.
In the Genesee section (fig. 357) the strata 1 and 2 correspond to 2 and 3 of
these divisions; and the Niagara section contains 2, 3, and 4.
Structural peculiarities.—The beds bear evidence of having been
formed as a sand-flat or reef-accumulation. Besides the thin
lamination alluded to, they abound in ripple-marked slabs (fig. 02);
mud-cracks (figs. 04,65), due to sun-drying; wave-lines; rill-marks
about stones and shells (fig. 03) ; and diagonal lamination (fig. 01 e),
an effect of tidal currents. Fig. 03 is drawn from a slab of Medina
sandstone. All these peculiarities evince that the accumulations,
while forming, were partly in the face of the waves and currents,
and partly exposed above the waves to the drying air or sun and
to the rills running down a beach on the retreat of the tides or
waves.
II. Life.
1. Plants.
Sea-weeds are common, and especially the Fucoid Arthrophycus
Harlani (fig. 358). The stems are transversely furrowed, and look a
little as if jointed,—to which peculiarity the name alludes (from
apdpov, a joint, and <pvnoQ,fucus, a kind of leathery searweed).
NIAGARA PERIOD—CLINTON EPOCH.
233
2. Animals.
The arenaceous and shaly character of the beds is unfavorable
for Radiates, and only a rare coral or Crinoidal fragment has been
met with.
Figs. 358-363.
Fig. 358, Arthrophycus Harlani; 359, Lingula cuneata; 360, Modiolopsis orthonota; 361, M. ?
primigenius; 362, Pleurotomaria litorea; 363, Bucania trilobata.
Of Mollusks, the most common species is the Braehiopod Lingula
cuneata (figs. 359 and 63), which sometimes thickly covers large
surfaces, and is a good mark of the epoch.
Among the few other species there are the following :—Fig. 360, Modiolopsis
orthonota j 361,3/. ? primigenius ; 362, Pleurotomaria litorea II.; 363, Bucania
trilobata, different views. Orthocerata are occasionally met with.
The only Crustacean described is the Ostracoid Leperditia cyltndrica.
The Medina epoch is closely related in its rocks and fossils to the
Clinton epoch.
3. CLINTON EPOCH (5 c).
I. Rocks : kinds and distribution.
The Clinton rocks have a wide range over the country. In the
Interior Continental basin they fail in New York on the Hudson ; but,
commencing near Canajoharie, they stretch westward across the
State beyond Lake Ontario, through Canada. They occur farther
west, in Michigan, Ohio, and the States west, to the Mississippi, and
perhaps also beyond the Mississippi, in Iowa. The formation is
200 feet thick in some parts of New York; to the west it is very
thin, and in the States bordering on the Mississippi it is seldom
recognizable.
In the Appalachian region the strata have been observed in Penn-
234
PALAEOZOIC TIME UPPER SILURIAN.
sylvania, Virginia, and Alabama. The thickness in the first of
these States is in some places 2000 feet.
The rocks in New York and along the northern border of the
United States are mostly shaly sandstones or flags and shales, with
some layers of limestone. But in the Michigan peninsula, and to
the south, limestone predominates.
The sandstone is often quite hard, and much of it has the surface
uneven from knobby and vermiform prominences, some of which
are due to Fucoids.
In many regions, as in central New York, Ohio, and Wisconsin,
there are one or more thin beds of red argillaceous iron-ore, called
lenticular ore, from the small flattened grains which compose it.
In the Eastern border region, at Anticosti Island, the limestones
of this period are several hundred feet thick. Shales with lime¬
stone occur in northern Nova Scotia.
a. Interior Continental basin.—On the Genesee (see fig. 357, p. 231), the Clinton
group consists of,—
(1.) 24 feet of green shale, of which the lower part is shaly sandstone and tho
upper part an iron-ore bed ; (2.) 14 feet of limestone, called Pentamerus limestone
from a characteristic fossil; (3.) 24 feet of green shale ; (4.) 18 J feet of limestone,
called the upper limestone.
On the Niagara (see section, fig. 357 A, p. 232), there is only a shale 4 feet
thick, without the iron-ore, overlaid by a limestone stratum 25 feet thick,—this
limestone corresponding to the three upper divisions, and its upper 20 feet to the
upper limestone. To the eastward, in Oneida, Herkimer, and Montgomery
counties, the rock is 100 to 200 feet thick, and includes no limestone, though
partly calcareous. The group consists of shale and a hard grit or sandstone
in two or more alternations, along with two beds of the lenticular iron-ore.
The flattened grains making up this ore are concretions like those of an oolite.
Near Canajoharie—which is not far from its eastern limit—the formation has a
thickness of 50 feet. In the town of Starkville, Herkimer co., the rock contains
a good bed of gypsum.
In Ohio, the Clinton group is recognized by its Fucoids, overlying tho Blue
limestone of Cincinnati. In Wisconsin, the bed of lenticular iron-ore is 6 to 10
or even 15 feet thick.
In Michigan, south of Lake Superior, and about the northeastern shores of
Lake Michigan, the rocks are limestone with hard sandstones and shales like
those of central New York. The thickness in the peninsula is 51 feet.
b. Appalachian region.—In Pennsylvania, Professor Rogers divides the rock
into (1) a lower slate, which at Bald Eagle Mountain is 700 feet thick; (2) iron-
sandstone, 80 feet in the Kittatinny Mountain; (3) upper slate, 100 to 250 feet;
(4) lower shale, 100 to 250 feet; (5) ore-sandstone, 25 to 110 feet; excepting the
last, these strata augment in thickness to the northwest; (6) upper shale, 120
to 250 feet, which thickens to the northwest; and (7) red shale or marl, 975
feet thick, at the Lehigh Water-Gap. The formation spreads across the
State " from the northwest flank of the Kittatinny Mountain to the similar
NIAGARA PERIOD CLINTON EPOCH.
235
slope of the last main ridge of the foot of the Alleghany Mountains." (II. D.
Rogers.)
c. Eastern border region.—The total thickness of the series of limestones at
Anticosti is 1344 feet. Of this, 734 feet have been supposed to "show a passage
from the Upper to the Lower Silurian." (J. Richardson, in Logan's Report.;
But according to Shaler, the whole series belongs to the Upper Silurian, and it
extends into the Niagara epoch.
In Nova Scotia, as described by Dawson, the strata occur on the northern
coast. At Arisaig, where the rocks are shales and limestone and have a thick¬
ness of about 500 feet, fossils occur through the formation and are very abundant
in the upper or more calcareous part. At the East River of Pictou there arc
also slates and calcareous bands, probably of this epoch. They include a deposit
of oolitic iron-ore, like that of the Clinton rocks of central New York, which
in some places has a thickness of 40 feet.
South of the St. Lawrence, Clinton beds occur on the river Chotte.
n. Life.
The rocks of the Oneida and Medina epochs, as they afford but
few fossils, give no assurance that the waters had been fully resu])-
plied with life after the destruction that closed the Lower Silurian.
But in the beds of the Clinton epoch fossils again abound, and the
Niagara strata, which follow, bear full testimony to a populous
globe.
1. Plants.
Great numbers of Fucoids occur in the Clinton beds of central
New York, differing from those below. They are of various dia¬
meters, from the size of a finger and larger to
that of a thread.
One of the most characteristic species is re¬
presented in fig. 3G4. No traces of land-plants
are known.
2. Animals.
Many of the limestones were coral reefs, and
abound in corals, a few of which are repre¬
sented in figs. 365-3G8. Graptolites (figs.
3G9, 3G9 a) continue in the waters over the
muddy bottoms, but the genus here became
extinct. Bracliiopods were common: among
them the genus Pentamerus has here its earliest
species, and P. oblongus (fig. 371) was especially
abundant. The tracks of some of the Mollusks
are found on some layers. Fig. 381 is a portion
of one, reduced one-half: it resembles the track made in the mud
by some Unios. Fig. 382 represents what is supposed to be the
Fig. 304.
Rusophycus bilobatus.
236
PALAEOZOIC TIME UPPER SILURIAN.
trail of a sea-worm, or Annelid, reduced one-half. There were also
Orthocerata and Trilobites.
Characteristic Species.
1. Radiates.—(a.) Polyps.—Figs. 365, 366, Zaphrentis (Caninia) bilaleralis ;
367, Paloeocyclus rotuloides, different views, from New York; 368, a branching
Figs. 365-369.
Radiates.—Figs. 365, 366, Zaphrentis bilateralis; 367, Palseocyclus rotuloides; 368, a, Chas-
tctes; 369, a, Graptolithus Clintonensis.
Chsetetes. (5.) Acalephs.—369, a, Graptolithus Clintonensis. (c.) Ecliinoderms :
Criuoids.—A few species are known : fragments are common, and they are often
found in the iron-ore as well as in the limestones.
Mollusks.—Figs. 370, a, Fenestella ? prisca; 371, Pentanierus oblongus; 372, 373, part of
casts of the interior; 374, 375, Atrypa reticularis; 376, 377, Athyris (formerly Atrypa)
congesta; 378, Chonetes cornuta; 379, Avicula rhomhoidea; 380, Cyclonema cancellata;
381, track of a Bivalve ( X %); 382, track of an Annelid? ( X %)■
2. Mollusks.—(n.) Bryozoans.—Fig. 370, Fenestella? prisca.
NIAGARA PERIOD—NIAGARA EPOCH.
237
(b.) Brachiopods.—There are species of Lingula, Orthis, Leptoena, Rhyncho-
nella, Spirifer, and also of the new genera for America, Chonetes and Pentamerus.
Fig. 371, Pentamerus oblongua ; some specimens are more than twice the size of
this figure, and very thick; it is abundant in New York State and the West, and
occurs also in Britain; figs. 372, 373 show casts of the interior,—372 a dorsal
view, and 373 a ventral. Figs. 374, 375, Atrypa reticularis, or a related species;
the A. reticularis is reputed to extend through the Niagara period into the
Hamilton of the Devonian; but more than one species are probably here in¬
cluded; this also is a foreign species: it is one of the few species of true Atrypa;
the interior of the shell is shown in fig. 215. Fig. 376, Athyris ? congesta ; fig.
377, same, different view,—it has a spire within, extending downward and out¬
ward ; fig. 378, Chonetes cornuta Koninck.
(c.) Conchifers.—Fig. 379, Avicula rkomboidea H.
(d.) Gasteropoda.—Fig. 380, Cyclonema cancellata H. Bucania trilobata of the
Medina also occurs here, besides other Univalves.
(e.) Cephalopoda.—There are a few Ortlwcerata.
3. Articulates.—Remains of Trilobites of the genus Homalonotus, and
of the same species figured under the Niagara epoch. Tracks or scratches occur
which have been referred with good reason to Crustaceans, besides others like
fig. 382, that are attributed to Worms.
Among the Clinton species are the following from the Lower Silurian :—Orthis
Lynx, Lepisena sericea, Bellerophon bilobatus. The following are known in
Europe :—Orthis Lynx, Chonetes cornuta, Atrypa reticularis, A. hemispherica, Spi¬
rifer radiatus, Pentamerus oblongus.
NIAGARA EPOCH (5 d).
I. Rocks : kinds and distribution.
The Niagara and Clinton epochs had several points of similarity.
(1.) The formations thin out to the eastward in New York. (2.)
The rocks are shales and limestone, but the latter increases in pro¬
portion in central and western New York, and becomes the
prevailing material of the formation through the interior of the
Mississippi basin, while along the Appalachians in Pennsylvania
and farther south the rocks are almost solely shales. (3.) A con¬
siderable number of the Clinton fossils reach up into the Niagara
formation.
On the contrary—(1.) The Niagara beds spread more widely
over the continent,—occurring through a large part of the Interior
Continental basin, from New York to beyond the Mississippi, and
from Michigan to Tennessee, as well as along the Appalachian region
in Pennsylvania and Virginia to Alabama; also at various places in
the Arctic, and in other parts of British America, as on the borders
of Hudson Bay. (2.) The great majority of the species are not
found in the Clinton beds, and the species are more generally clear-
238
PALAEOZOIC TIME UPPER SILURIAN.
water species, as Corals and Crinoids. (3.) The Niagara epoch was
eminently one of the limestone epochs of the American Silurian.
The limestones are usually made up of fossils, and are often mag-
nesian. In western New York, near Niagara Falls, there are 165
feet of limestone (directly at the Falls, 85 feet) overlying 80 of
shale (fig. 357 A); and the undermining of the limestone by the
falling waters, which readily remove the shale, is the occasion of
the slow retrocession of the Falls. Along the Appalachian region
in Pennsylvania, the beds have a thickness exceeding 1500 feet,—
thus, like the earlier formations, surpassing many times in extent
the beds of the interior basin.
a. Interior Continental basin.—At Rochester, N.Y., there are about 80 feet of
limestone, overlying 80 of shale. Farther eastward, in Wayne co., the lime¬
stone is 30 or 40 feet thick, and in Cayuga co. still less. The formation thins
out altogether in Herkimer co.
In the States west of New York the limestone lies directly upon the Clinton
limestone. In the peninsula of Michigan the thickness is about 100 feet
(Winchell). In Ohio, Indiana, and Illinois, this rock and the Corniferous over¬
lying it have been called the Cliff-limestone, because it often stands in bold
bluffs along the river-valleys. Such bluffs are a common feature in all lime¬
stone regions where the strata are nearly horizontal and in heavy beds.
In the Helderberg Mountains there is a layer of limestone 25 feet thick, called
Coralline limestone, which has been referred to the Niagara epoch. It has been
suggested that it should be united rather with the overlying formation.
b. Appalachian region.—In Pennsylvania the formation consists of two dis¬
tinct deposits of marl or fragile shale. The lower is about 450 feet thick where
most developed, near the middle belt of the Appalachian zone, and decreases
both to the southeast and northwest. The upper deposit is 1200 feet thick
in the northwest belt, and declines to the southwest (H. D. Rogers). These
strata may include, besides the true Niagara, strata of the Salina or Salt-
group period.
c. Eastern border region.—The Niagara limestone is supposed to occur in
eastern Canada some distance south of the St. Lawrence, in the course of a
limestone belt running between northern Vermont and Gaspe on the gulf; but
it has not yet been identified with certainty.
Near New Canaan, in Nova Scotia, there are clay slates of the Niagara
epoch.
d. Arctic regions.—In the Arctic, the Niagara limestone has been observed
between the parallels of 72° and 76° on the shores of Wellington and Barrow
Straits, and on King William's Island. The common Chain-coral Hahjsitcs
(Catenipora) catenulata has been found at several localities, along with other
Upper Silurian species. (See, further, p. 242.)
The color of the Niagara limestone is commonly dark bluish-gray to drab.
It is sometimes quite impure, and good for hydraulic purposes. A specimen
from Makoqueta, Jackson co., Iowa, afforded J. D. Whitney—carbonate of lime,
52.18, carbonate of magnesia, 42.64,—with 0.35 of carbonate of soda, a trace of
NIAGARA PERIOD NIAGARA EPOCII.
239
potash, carbonate of iron, chlorine, and sulphuric acid, 0.63 of alumina and
sesquioxyd of iron, and 4.00 insoluble in acid,—making it nearly a true do¬
lomite.
The structure of the limestone is often nodular or concretionary. In Iowa
and some other parts of the West the rock abounds in chert or hornstonc, which
is usually in layers coincident with the bedding, like flint in chalk, and the
fossils are all siliceous. At Lockport, N.Y., cavities in the limestone allord fine
crystallizations of dog-tooth spar (calcite) and pearl-spar (dolomite), with gyp¬
sum, and occasionally celestine, and still more rarely a crystal of fluor. The
limestone sometimes breaks vertically with smooth columnar surfaces,—a pecu¬
liarity which has been attributed to the crystallization of a foreign substance.
II. Life.
Corals and crinoidal remains are so abundant in the Niagara
limestones, and, in many places, so far make up the rock, that
the beds have been well called old coral reefs. The variety of life
about the reefs was very great. We find, besides the flowering
Corals and the slender-rayed Crinoids, great numbers of Bracliio-
pods, some Concliifers, large Orthocerata, and many new kinds of
Trilobites. There is no evidence of any fishes, and none of life
over the land or in fresh waters.
Figs. 383-388 represent some of the Corals. Fig. 383, one of
the Cup-corals; fig. 385, Hahjsitcs catenulata, projecting above the
limestone in which it is imbedded,—it is often called Chain-coral,
from the appearance in a transverse section ; fig. 384, Favo.sites Nia-
Figs. 383-388.
Corals.—Fig. 383, Chonophyllum Niagarense; 384, a, Favosites Niagarensis; 385, Ilalysites
catenulata; 386, 387, Heliolites spinipora; 388, Stromatopora concentrica.
garensis, a Coral of a columnar structure, with horizontal partitions
in the cells. Three out of the many fine Crinoids are represented
240
PALAEOZOIC TIME UPPER SILURIAN.
in figs. 389—391; Brachiopods, in figs. 392—404; Conchifei^s and
Grasteropods, in figs. 405-407 ; Trilobites, in figs. 408-411. Penta-
merus oblongus of the Clinton epoch (fig. 371) is abundant in the
Niagara limestone of Wisconsin and Iowa.
Characteristic Species.
1. Radiates.—(a.) Polyps (Corals).—Fig. 383, Chonophyllum Niagarcnst
(Conophyllum of Hall, a genus first published in 1852, two years after Chono¬
phyllum by Edwards); 384, Favosites Niagarensis; 384 a, surface of same,
enlarged, showing outline of cells; 385, Haly sites catenulata; 386, Heliolites
spinipora H.; 387, an enlarged view, showing the 12-rayed cells and the inter¬
val of a cellular character separating them, both of which are distinguishing
characteristics of the genus Heliolites ; 388, Stromatopora concentrica.
(b.) Echinoderms.—Fig. 389, Ichthyocrinus Levis Conrad, a species which is
sometimes twice as large as the figure; 390, Caryocrinns ornatus Say, of Lock-
port, the nut-like shape having suggested the generic name (from Carya, the
hickory-nut); 391, Stephanocrinus angulatus Conrad, of Lockport; a, part of
the stem, enlarged; b, joint of the stem, top-view : c, base of the body, showing
the three pieces of which it consists. Also, fig. 156 (page 148), the Cystid
Callocystites Jewettii H., and fig. 154, the Star-fish Palseaster Niajarensis.
Figs. 389-391.
89
MP. *&.<: ■' •:
JSfiS
k4'|
ft' t'«j ;•$! pfd: •£? 1°IH
" iwl!
IS.? jgf
g W
• %
i m
g 1
i *£
% Mm 1
Crinoids.—Fig. 389, Ichthyocrinus lsevis; 390, Caryocrinus ornatus; 391, a, b, c, Stephano¬
crinus angulatus.
2. Mollusks—(a.) Bryozoans.—Many species of delicate corals of the
genus Fenestella, resembling fig. 370, and of other genera, (b.) Brachiopods.—
Fig. 392, Strophomena rugosa ; 393, Leptsena transversal!s Dalman ; 394, Atrypa
nodostriata, the Niagara form of this species; 395, same, side-view; 396, Me-
rista hitida ; 397, Pentamerus interplicatus ; 398, a, Bhynchonella cuneata ; 399 a, b,
Leptocoelia disparilis; 400, Orthis bilobus; 400 a, same, enlarged; 401, Spirifer
Niagaremis ; 402, same, side-view; 403, 404, Sp. sidcatus. Among these, all but
the Leptocoelia disparilis, Atrypa nodostriata, and the Orthis and Spirifers, are
found also in European rocks.
NIAGARA PERIOD—NIAGARA EPOCH.
241
(c.) Concliifers.—Fig. 405, Avicula emacerata.
(d.) Gasteropods.—Fig. 406, Platyostoma Niagarensis; 407, Platyceras angu-
Figs. 392-404.
Brachiopods.—Fig. 392, Strophomena rugosa; 393, Lepttena trausversalis; 394, 395,
Atrypa uodostriata; 396, Merista nitida; 397, Pentamerus interplicatus; 39S, a, Rhyn-
chonella cuneata; 399, a, b, Leptoccelia disparilis; 400, a, Ortliis biloba ; 401, 402, Spirifer
Niagarensis ; 403, 404, Sp. snicatus.
latum, a true univalve, but loosely and imperfectly coiled, as shown in the
profile view, fig. 407
Figs. 405-407.
Conchifer and Gasteropods.—Fig. 405, Avicula emacerata; 406, Platyostoma Niagarensis;
407, a, Platyceras angulatum.
(e.) Cephalopoda.— Species of Orthoceras, Cyrtoeeras, Gomphoceras, and of
ConulaHa. The last probably belongs to the division of Ccphalopods having
internal shells.
3. Articulates.—(a.) THlobites.—Fig. 408, Dahnania limidurus (a genus
differing from Calymene in having the glabella, or middle region of the buck¬
ler, largest anteriorly, besides having large reniform eyes and other pecu¬
liarities); 409, Lichas Boltoni,a. large and characteristic species, much reduced;
410, Homalonotus delphinocephalus (the genus having very small eyes, the glabella
faintly outlined and undivided,—the middle lobe of the body much broader
than the lateral); 411, Illeenus Barrieutis; Calymene Blumenbachii var. Niaga-
17
242
PALAEOZOIC TIME—UPPER SILURIAN.
rensis, near fig. 177 (page 151). (?>.) Ostracoids, or bivalve Crustaceans.—
Fig. 412, Beyrichia symmetrica, showing one of the valves; a, same, natural
size.
Figs. 408-412.
Crustaceans.—Fig. 408, Dalmania limulurus (X A)'\ 409, Lichas Boltoni (X A) > 410, Ho-
malonotus delphinocephalus (X 14) > 411, Illcenus Barriensis (X x/t) > 412, Beyrichia sym¬
metrica ; 412, a, same, natural size.
The following are some of the species common to the Niagara and Clinton
groups:—
Halysites catenulata (fig. 385).
Caryocrinus ornatus (fig. 390).
Hypanthocrinus decorus.
Lingula lamellata.
Orthis elegantula (fig. 329).
Strophomena rugosa (fig. 392).
Pentamerus oblongus (fig. 371).
Rhynehonella neglecta.
Atrypa reticularis (fig. 374).
Spirifer radiatus.
Avicula emacerata (fig. 405).
Orthonota curta?
Modiolopsis subalatus ?
Ccraurus insignis.
Homalonotus delphinocephalus (fig. 410).
Calymene Blumenbachii.
Dalmania limulurus (fig. 408).
Illsenus Barriensis (fig. 411).
According to Salter, a number of species of the Upper Silurian, and probably
of this part of it, have been observed in the Arctic; as, Halysites catenulata,
Orthis elegantula, Favosites Gothlandica, Leperditia Baltica, species of Calo-
phyllum, Heliolites, Cystiphyllum, Cyathophyllum, Syringopora, with Pentamerus
Conchidium, Atrypa reticularis, etc.; and at the southern extremity of Hud¬
son's Bay, Pentamerus oblongus, Atrypa reticularis, etc. About Lake Winnipeg,
also, Upper Silurian fossils have been found. See Am. Jour. Sci. [2], xxi. 313,
xxvi. 119.
The fossils of the Coralline limestone (p. 238), as Hall states, are mostly
peculiar to it. Out of 32 species (including Corals, Brachiopods, Conchifers,
Gasteropods, Cephalopods, and Crustaceans) only the following are set down as
identical with Niagara fossils :—Favosites Niagarensis, Stromatopora concentrica,
NIAGARA PERIOD.
243
Halysites catenulata, Spirifer crispas, Atrypa lamellata; and these are not all
beyond doubt. Moreover, three of them are cosmopolite species. The beds are,
therefore, strikingly different in life from the Niagara, and appear to represent
a later epoch. Among the species there are very large spiral chambered shells
of the new genus Trochocevaa Hall, which are unknown, in other formations.
General Observations on the Niagara Period.
Geography.—The facts upon which we have to rest our conclu¬
sions with regard to the geography of the Niagara period are,—
1st. The occurrence of the Oneida conglomerate over the region
from central New York southward through the length of the
Appalachians.
2d. The Medina sandstone covering the same region, but spread¬
ing a little farther westward on the north.
3d. The Clinton group having the same range on the east and
extending over a considerable part of the inferior basin to the
Mississippi; shales characterizing the formation in the Appala¬
chian region, shales and sandstones prevailing over limestone in
New York, and limestones, more or less argillaceous, mostly con¬
stituting the beds in the West.
4th. The Niagara rocks having nearly the same eastern limit in
New York (that is, absent almost entirely from the eastern third of
the State); spreading over the Appalachian region and also through
a large part of the interior basin; consisting of shales with some lime¬
stone in central New York, more limestone in the western part of the
State, shales almost solely in the Appalachians, limestones in theWest.
5th. The formations six to eight times thicker in the Appala¬
chians than in the West.
The position of the coarse conglomerate rocks of the Oneida epoch,
spreading neither over eastern New York nor the interior basin
west of the State, apparently indicates that along its line was the
sea-coast of the time, and that the ocean reached it in full force.
Such coarse beds of marine formation are formed either in front
of the waves, or under the action of strong marine currents. The
latter never have sufficient force for the purpose, except in narrow
straits and over limited areas, and are not capable of making
accumulations of so great extent. It is stated on page 228 that
the Appalachian region in Vermont, if not also in southern New
England, must have been out of water: the absence of this forma¬
tion and the others of the Magara period from eastern New York
harmonizes with this view.
The fine sandy and clayey character of the Medina beds shows
244
PALAEOZOIC TIME UPPER SILURIAN.
that at this time the same coast-region must have become an ex¬
tensive area of low, sandy sea-shores, flats, and marshes, not feeling
the heavy waves ; and this kind of surface extended westward
over Michigan, instead of having a limit in central New York.
There is abundant evidence, in the ripple-marks, wave-marks, rill-
marks, and sun-cracks, of shallow waters, emerging sand-flats, and
low shores.
The clays, clayey sandstones, and limestones of the Clinton
epoch through New York and the Appalachians show that the
Medina condition of the coast-region still continued, except that
the marshes were at times shallow seas where impure limestones
could be formed; and the many alternations of these limestones
with shales and sandstones imply frequent changes of depth over
these areas, as remarked by Hall. At the same time, the westward
extension of the formation, and the prevalence of limestones, indi¬
cate that the waters occupied a considerable part of the Interior
Continental basin; while the impurity of the rock suggests that these
inner seas were in general quite shallow. The beds of argillaceous
iron-ore, which spread so widely through New York and some of
the other States west, could not have been formed in an open sea;
for clayey iron-deposits do not accumulate under such circum¬
stances. They are proof of extensive marshes, and, therefore, of
land near the sea-level. The few fragments of Crinoids and shells
found in these beds are evidence that they were, in part at least,
salt-water marshes, and that the tides sometimes reached them.
The shales of the Niagara epoch on the east indicate no great
alteration of the coast-region after the Clinton epoch ; but the
increasing proportion of limestones to the westward, and their
great thickness and comparative purity in western New York, and
still greater prevalence in the States beyond, teach that the inte¬
rior sea had become nearly what it was in the Trenton period. It
was, however, more beautiful in its life; for Corals and Crinoids
were a marked feature of the epoch.
Let us turn back now to the Trenton period, in review. There
was then a shallow sea over the whole interior (with small excep¬
tions), and it covered even the Appalachians, for here, also, lime¬
stones were formed ; and any sea-coast of sands, pebbles, or muddy
flats must have been farther east, where some portion of the con¬
tinental border may have been raised to the surface through a
slight bending upward of that part of the earth's crust. (This
border now extends to a line 80miles at sea [see p. 12 and fig. 664].)
In the Hudson period there appears to have been a partial sub¬
sidence of the outer barrier and a shallowing of the interior sea by
f
NIAGARA PERIOD.
245
the rising of the bottom. In the Oneida epoch, which opened the
Upper Silurian, we have evidence only of an exposed coast-line in
the face of the waves,—the former barrier being more sunken, and
the bottom of the Interior Continental sea risen quite above the
level of the waters, so as to make dry land where before was a pro¬
fusion of marine life. In the Medina epoch the .bold sea-coast
becomes a flat coast-region, with sand-flats and marshes, and to the
northward the waters spread west of New York State. In the Clin¬
ton epoch the coast-region is similar to that in the Medina, but the
waters cover largely the Mississippi basin, and the interior sea once
more begins to appear. In the Niagara epoch the Interior Conti¬
nental basin is again a continental sea full of marine life, and through
a large part of it limestone reefs are in progress.
If the above is a correct view of the geographical changes, it is
seen that they consisted in a grand though small oscillation over
the continent,—a rising and sinking again of . the interior ; and in
its course the interior seas became dry land at the close of the
Lower Silurian. If so, there is no need of any other explanation
of the extinction of life that then happened, or of the exception
to the thoroughness of the extinction in the Eastern border basin
at Anticosti,—if actually an exception (p. 231).
In the course of these oscillations, from the beginning of the
Trenton to the close of the Niagara period, 12,000 feet of rock were
deposited along the Appalachians. From this datum the slowness
of the oscillation may be estimated. The whole amount of change
of level over the Interior Continental basin may not have exceeded
1000 feet.
But the Appalachian deposits show a vast amount of subsidence
which was in slow progress as the accumulations went on. Without
the subsidence, great breadth of deposits might have been formed,
but not great thickness.
With regard to the continent beyond the Mississippi we have small basis for a
conclusion. About the Black Hills and Laramie Range Dr. Ilayden found the
Carboniferous strata resting on those of the Potsdam period, and, therefore, an
absence of all the formations of the Lower Silurian above the Potsdam, of all
the Upper Silurian, and of all the Devonian. Similar facts are reported from
Arkansas. About the El Paso Mountains in New Mexico, between the rivers
Pecos and Grande (near lat. 32°), Dr. G. G. Shumard found a limestone of the
Trenton or Hudson periods, containing the fossils Orthis testudinariix, 0. occi-
dentalis II., Rhynchonella capax Conrad, and others; hut to this succeeded the
Carboniferous. It -would seem, therefore, that a part of the region beyond the
Mississippi, was in no condition for the formation of limestones or sandstones
between the Lower Silurian and the Carboniferous; and the most probable sup¬
position is that the land was not under water, although it was afterwards ex-
246
PALAEOZOIC TIME UPPER SILURIAN.
tensively submerged in the Coal era. Had the absence of these formations been
due to deep submergence,—too deep for animal life,—the slopes of some of the
mountains—as the Laramie Range or Black Hills—would have borne evidence in
the presence about them of some of the beds representing the Lower Silurian
and Devonian periods. The larger part of the eastern slope of the Rocky
Mountains is covered by Mesozoic and later strata; and hence no certain
inference can be drawn as to the extent of this dry land.
The Niagara period was a period of continental submergence also
in Arctic America and Europe at this time. Even Great Britain
had its Coral and Crinoidal seas, and limestone formations in pro¬
gress,—although the Silurian there contains comparatively little
limestone, owing to the fact that the country lies, like the Appa¬
lachian region, within the mountain-border of a continent.
Life.—Remarks with regard to the life of the period are deferred
till the closing pages on the Upper Silurian, with a single excep¬
tion. There is abundant evidence of extensive low flats and
marshes over the continent in the Medina and Clinton epochs:
the ore-beds of the latter are decisive proof on this point. The
absence, therefore, of the remains of land-plants from these beds
may be regarded as nearly sure demonstration that no land-plants
then existed. Taking this into connection with the evidence from
other regions, and the other formations of the period, there can be
no reasonable doubt on this point.
SALINA PERIOD (6).
Epochs.—1. Guelph epoch, or that of the Guelph and Gait
limestones (6 a); 2. Saliferous epoch, or that of the Onondaga
Salt group (6 b).
I. Rocks : kinds and distribution.
The Niagara period had covered the sea-bottom mainly with
limestones. With the opening of the Salina period there was a
change by which shales or marls and marly sandstones, with some
impure limestones, were formed over a portion of New York ; and
in some way the strata were left impregnated with salt, and also
almost destitute of fossils.
The beds spread through New York, and mostly south of the
Erie Canal. They are 700 to 1000 feet thick in Onondaga and Cayuga
cos., and only a few feet on the Hudson.
The following sections (figs. 413, 414, from Hall), taken on anorth-
and-south line south of Lake Ontario, show the relations of the
Salina beds (6) to those above and below,—they being underlaid
SALINA PERIOD.
247
in one section (fig. 414) by the Niagara (5 d), Clinton (5 c), and
Medina (5 b) beds, and overlaid in the other (fig. 413) by rocks
Fig. 413.
353??
11
10c
106
6
T
9 10 a
Fig. 414.
56
5 c
5 d 6
of the Lower and Upper Helderberg (7, 9), Hamilton (10 a, 10 b,
10 c), and Chemung groups (11).
To the westward they outcrop between Niagara and Lake Huron,
and also about Mackinac; beyond, thin beds in Wisconsin and
Iowa have been referred to this period.
In western Canada the formation is underlaid by a limestone at
Gait, Guelph, and other places. The Leclaire limestone, of Iowa,
has been referred to this epoch, but is now regarded as closing the
Niagara period.
In Onondaga eo., N.Y., the beds in the lower half are (1) tender, clayey deposits
(called marls) and fragile clayey sandstones of red, gray, greenish, yellowish,
or mottled colors ; and in the upper half (2), calcareous marls and an impure
drah-colored limestone containing beds of gypsum, overlaid by (3) an hydraulic
limestone. This limestone afforded Dr. Beck on analysis—Carbonate of lime,
44.0, carbonate of magnesia, 41.0, clay, 13.5, oxyd of iron, 1.25. The upper
division is said to contain acicular cavities once filled by Epsom salt (sulphate
of magnesia). The rock is sometimes divided by columnar striations like the
Lockport limestone, and the structure has been attributed to the crystallization
of the magnesian sulphate (Yanuxem), or else to that of salt or gypsum (Hall).
The seams sometimes contain a trace of coal or carbon.
Near Syracuse there is a bed of serpentine in this formation, along with
whitish and black mica and a granite-like rock. (Vanuxem.) In part of it horn¬
blende replaces the mica, making a syenite. There is little evidence of heat in
the beds adjoining these metamorphic rocks.
In the peninsula of Michigan the formation includes—beginning below—10
feet of variegated gypseous marls, 14 feet of ash-colored argillaceous limestone,
3 feet of calcareous clay, and 10 feet of chocolate-colored limestone. (Winchell.)
The rocks of this period have not been distinguished from those of the
Niagara period in the Appalachian region in Pennsylvania or to the southwest
in Virginia.
The beds, especially those of the upper half, are much inter-
248
PALAEOZOIC TIME UPPER SILURIAN.
sected by shrinkage-cracks,—effects of the drying of the mud of the
ancient mud-flat by the sun.
Minerals.—The gypsum does not constitute layers in the strata,
but lies in imbedded masses, as shown in the annexed figures.
Fig. 415.
Fis;. 410.
j *'A
d
c
a
b
a
The lines of stratification sometimes run through it, as in fig. 416;
and in other cases the layers of the shale are bulged up around
the nodular masses (fig. 415). Both cases show that the gypsum
was formed after the beds were deposited. Sulphur springs are now
common in New York, and especially about Salina and Syracuse.
Dr. Beck describes several occurring in this region, and mentions
one near Manlius which is "a natural sulphur-bath, a mile and a
half long, half a mile wide, and 168 feet deep,—a fact exhibiting in
a most striking manner the extent and power of the agency con¬
cerned in the evolution of the gas," and showing, it may be added,
that the effects on the rocks below must be on as grand a scale.
These sulphur-springs often produce sulphuric acid by an oxyda-
tion of the sulphuretted hydrogen. There is a noted "acid spring"
in Byron, Genesee co., N.Y., connected with the Onondaga forma¬
tion, besides others in the town of Alabama. This sulphuric acid
acting on limestone (carbonate of lime) drives off its carbonic acid
and makes sulphate of lime, or gypsum; and this is the true theory
of its formation in New York. The laminae which pass through
the gypsum unaltered, as in fig. 416, are those which consist of
clay instead of limestone. The gypsum is usually an earthy variety
of dull gray, reddish and brownish, sometimes black, colors. It
may have been produced at any time since the deposition of the
rocks ; and it is beyond doubt now in jirogress at some places in
the State.
The salt of the rocks is found only in solution in waters issuing
from the strata. At the present salt-works of Salina and Syracuse
the brine is obtained by borings. The wells are 150 to 310 feet deep
at the former place, and between 255 and 340 at the latter. 35 to
45 gallons of the water afford a bushel of salt; while it takes 350
gallons of sea-water for the same result.
SALINA PERIOD.
249
II. Life.
The Salina beds are for the most part destitute of fossils. The
lower beds in New York contain a few species imperfectly pre¬
served ; and the same is true of the upper. The latter, however,
are regarded as rather of the next ("upper xfelderberg) period.
In the limestone at Gait there are a number of shells, and two of them—Mur-
rhisonia Boydii and Cyclonema sulcata—are set down by Hall as identical with
species in the lower part of the Onondaga Salt group. The fossils of this Guelph
Fig. 416 A.
Megalomus Canadensis.
formation are almost wholly different from those of the Niagara beds.
Fig. 416 A represents one of the Conchifers, the Megalomus Canadensis, a spe¬
cies that is occasionally found four inches long. Besides this there are a Penta-
merus, P. occidentalis, species of Jfurchisonia, an Orthoceras, and a Calymene,
besides Favosites Gothlandica, Halysites catenulata, etc.
General Observations.
Geography.—The position of the Saliferous beds over the State
of New York indicates that the region which in the preceding
period was covered with the sea and alive with Corals, Crinoids,
Mollusks, and Trilobites, making the Niagara limestone, had now
become an interior shallow basin, or a series of basins, mostly shut
off from the ocean, where the salt waters of the sea, which were
spread over the area at intervals,—intervals of days or months, it
may be,—evaporated and deposited their salt over the clayey bot¬
toms. In such inland basins the earthy accumulations in progress
250
PALEOZOIC TIME UPPER SILURIAN.
would not consist of sand or pebbles, as on an open sea-coast, but
of clay or mud, such as is produced through the gentle movements
of confined waters. Moreover, the salt waters would become under
the sun's heat too densely briny for marine life, and at times too
fresh from the rains ; and the muddy flat might be often exposed
to the drying sun, and so become cracked by shrinkage. The
shrinkage-cracks, the clayey nature of the beds, the absence of
fossils, and the presence of salt, all accord with this view. Salt can¬
not be deposited by the waters in an open bay, for evaporation is
necessary. The warm climate of the Silurian age and the absence
of great rivers were two conditions favorable for such results. At
one small coral island in the Pacific, visited by the author, the
lagoon (or lake) which formed the interior was shut off from free
communication with the ocean, and consequently some of the
above-mentioned conditions were well exemplified. The waters
became extremely salt in the hot season, and fresh in the rainy
months; and hence no living corals or shells existed there,
although once abundant. Moreover, while the rock was of coral
origin, there were no fragments of corals or shells along the shores
of this lagoon, but, instead, a deep mud of calcareous material,
made out of the broken shells and corals by the triturating wave¬
lets,—so deep and adhesive that the waters of the lagoon were
somewhat difficult of access. This calcareous mud, if solidified,
would become a non-fossiliferous limestone, like a large part of
the coral rock ; and yet a few hundred yards off on the sea-coast
there were other limestones forming, that were full of corals and
shells.
The Saliferous flats of New York spread across the State, and
probably opened on the ocean to the southeast. The existence of
such interior evaporating flats implies intermittent incursions of
the sea, perhaps only through tidal overflows, but probably such
occasional floodings as may take place where there are coast-bar¬
riers or reefs that are broken through at times by the waves or
currents.
• The existence of such barriers is no unreasonable assumption;
for the coast of the United States is now to a great extent bordered
with them. They stretch along the south side of Long Island,
shutting in a narrow area of salt water; and south of New York
they occur off New Jersey, Maryland, Virginia, and the Carolinas,
making the various sounds that are so characteristic of the coast-
region.
As the Saliferous beds of New York are nearly 1000 feet thick
just west of the centre of the State, and since there is proof in the
LOWER IIELDERBERG PERIOD.
251
shrinkage-cracks and other peculiarities that the layers were suc¬
cessively formed in shallow waters, it follows that there must have
been a slow subsidence of the region during the progress of the
period,—it may have been but a few inches or feet in a century.
In water ten feet deep, a bed ten feet thick, or a little over ten, may
form; but with a slow sinking, at a rate not beyond the rapidity of
deposition, the beds may reach any thickness, limited only by the
cessation of the subsidence.
Life.—The half-submerged marshes or flats of this period, bordered
by dry land at least on the north, and probably including dry areas
over their surface, would have given an opportunity for forest-trees
to grow and forest-animals to live where their remains would be
sure to find a safe burial, as they did in after-times. Yet, as in the
Medina and Clinton epochs, no trace of a leaf, or stem, or relic of a
land or fresh-water animal has been afforded by the beds.
The extermination of life at the close of the Niagara period was
very nearly complete in the region of New York, while apparently
only partial in the interior basin, as in Tennessee. The cause of the
extinction was connected, no doubt, with the changes that ushered
in the Salina period ; and the existence of seas over portions of the
interior accounts both for the limestones of the Salina ejaocli and
the continuation of a portion of the Niagara life beyond the termi¬
nation of the period. The beds of the Mississippi basin require a
fuller elucidation for safe inferences.
LOWER IIELDERBERG PERIOD (7).
I. Rocks: kinds and distribution.
The Lower Ilelderberg period was one of abundant marine life,
and of the formation of thick limestone strata,—a period, therefore,
not of prevailing salt marshes, but of clear seas over the submerged
land.
The formation in New York has its greatest thickness at the
Helderberg Mountains south of Albany, where it is over 200 feet;
and hence the name of the period.
The beds extend westward in New York, and gradually thin out
in Ontario county, being wholly absent from the western part ol
the State. The beds have been reported to occur in Ohio, Missouri,
'and Tennessee ; but according to the more recent investigations
they are wanting over the interior basin.
Near Montreal, in Canada, a small patch overlies unconformably
the Hudson River shales.
252
PAL2E0Z0IC TIME UPPER SILURIAN.
South of New York, along the Appalachian region they extend
through New Jersey, Pennsylvania, Maryland, and Virginia, in¬
creasing in thickness, being in all 500 feet or more on the Potomac ;
and, as in the North, they diminish westward.
The subdivisions of the formation observed in the Helderberg
Mountains are for the most part undistinguishable out of New
York State. The lowest rock, the Water-lime, retains its characters
most widely, and has a thickness on the Potomac of 350 feet (Ro¬
gers). Moreover, in New York it extends west to Ontario co., which
is beyond the beds higher in the series. The water-lime is so called
because used for making water- (or hydraulic) cement. It is a drab-
colored or bluish impure limestone, in thin layers.
The several New York subdivisions are as follow :—
5. Upper Pentamerus limestone.
4. Encrinal limestone.
4. Catskill or Delthyris shaly limestone.
2. Pentamerus limestone, 50 feet in the Ilelderberg Mountains.
1. Tentaculite and Water-lime group, 150 feet in the Ilelderberg Mountains.
An analysis of the Water-lime rock afforded Dr. Beck—Carbonate of lime, 48.4,
carbonate of magnesia, 34.3, silica and alumina, 13.85, sesquioxyd of iron, 1.75,
moisture and loss, 1.70. One of the beds of the Water-lime strata, consisting of
thin clinking layers, abounds in fossils called Tentaculites, and has been named
Tentaculite limestone.
The Pentamerus limestone (No. 2), overlying the Water-lime, is so called from
its characteristic fossil, Pentamerus (jaleatus (fig. 422). It is compact, and
mostly in thick layers. The Catskill or Delthyris shaly limestone (No. 3) con¬
sists of shale and impure thin-bedded limestone, and in many places in New
York abounds in the large fossil shell Spirifer macropleurus, and extends as far
west as Madison co. It is full of fossils. The Encrinal limestone (No. 4) is
confined to the eastern part of the State. The Upper Pentamerus (No. 5), the
upper layer, is of limited extent, but has many peculiar fossils : it is named
from the Pentamerus pseudo-galeatus (figs. 424, 425).
The Saliferous beds pass rather gradually into the Water-lime,—their upper
layers becoming more and more calcareous, and containing some of the Water-
lime fossils. The range of the Salina and Lower Ilelderberg formations is very
different; for the former is thickest west of the centre of New York, and the
latter on its eastern border.
In the Appalachian region in Pennsylvania the Water-lime group has in the
middle belt of the mountains a thickness in some places of 350 feet, while in the
southeast belt it is 50 to 200 feet; it thickens to the southwestward. The
rest of the Lower Helderberg, consisting also of impure limestones, has a
thickness of 100 feet or more in the middle belt, and 200 to 250 in the south¬
eastern, which thickness is maintained along the Appalachian chain. (Rogers.)
In the Eastern border region, at Pembroke, Me., in a granitic region, slates and
hard sandstones occur with many fossils; at other places in northern Maine, the
rock is limestone. In Cutler and Lubec, Me., there is a fossiliferous limestone,
either of this or the Niagara period. (C. II. Hitchcock.)
LOWER HELDERBERG PERIOD.
253
II. Life.
This period was prolific in species, beyond even the Niagara or
Trenton ; over 300 have been named and described. Among them
there are the same families and genera as in the preceding periods,
but with some marks of progress in new forms, and with a range
of species almost completely distinct. Yet it has been noted as a
striking fact that very many of the species of the Niagara period
have their closely-related or representative species in the Lower
Helderberg.
1. Plants.
Limestone strata seldom contain remains of
plants ; and, accordingly, little is known of the
botany of the Lower Helderberg period.
2. Animals.
Many Corals and Crinoids occur in the beds,
and some of the latter are of remarkable size
and beauty,— as the Mariacrinus nobilissimus,
and other species of the same genus. The last
of the Ha.li/sites, or Chain-coral, existed in this
period, and a few species of Cystids (figs. 417,418).
Brachiopods still take the lead in numbers of all
other kinds of life. In the Water-lime one
layer is full of the little Tentaculites ornatus (figs.
431, 432). Among the Trilobites the Dalmania
pleuroptyx (fig. 244 C) is a common form.
Quite a different form of Crustacean appears for
the first time in these rocks. It is represented
in the Eurypterus rcmipes Dekay (fig. 433). Un¬
like Trilobites, it has large jointed arms, and a Ai)10vystls> 418, Anoma-
' ° 0 7 locystis.
body which resembles that of the Sapphirina
and Caligus groups of modern Crustaceans. (Figs. 175, 176 repre¬
sent the female and male of a Sapphirina from our own seas. See
page 151.)
Characteristic Species.
1. Radiates.—(«.) Polyps.—Among Corals there are species of Zaphrentis,
Favosites, Stromatopora, Halysites, Syrinyopora, Chsetetes. (b.) Ecliinoderms.—■
Group of Cystideans : Fig. 417, Apiocystis Gebhardi, found in the Lower Pen-
tamerus; fig. 418, Anomalocystis, a remarkable species from the same rock. In
the group of Crinideans there are species of the genera Mariacrinus, Platycrinus,
Edriocriiius, Aspidocrinus, etc.
Figs. 417, 418.
Cystideans.—Fig. 417,
254 PALAEOZOIC TIME UPPER SILURIAN.
*
2. Mollusks. Brachiopods.—Fig. 419, Strophomena radiata Vanuxem,
of the Catskill shaly limestone; 420, 421, Rhynchonella ventricosa, of the
Figs. 419-430.
Brachiopods.—Fig. 419, Strophomena radiata; 420, 421, Rhynchonella ventricosa; 422, 423,
Pentamerus galeatus; 424, 425, P. pseudo-galeatus; 426, Eatonia singularis; 427, Merista?
sulcata; 428, Orthis varica; 429, Spirifer macropleurus; 430, Merista levis.
Upper Pentamerus; 422, 423, Pentamerus galeatus, of the Lower Pentamerus;
424, 425, P. pseudo-galeatus, of the Upper Pentamerus; 426, Eatonia singularis,
of the Catskill shaly; 427, Merista? sulcata, of the Water-lime; 428, Orthis
varica, of the Catskill shaly; 429, Spirifer macropleurtis, ibid.; 430, Merista
levis, ibid.
There are also Conchifers of the genus Aricula and others related; G-asten-
pods of the genera Platyceras, Platyostoma, etc. Also the Pteropod Tentaculitcs
ornatus (figs. 431, 432, the latter natural size).
3. Articulates (a.) Trilohites.— Fig. 244 C, Dalmania pleuroptyx ;
others of the genera Calymene, Cheirvrns, Asaphus. (h.) Other Entomostraeans.—
Fig. 433, Eurypterus remipes, of the Water-lime, natural size, from a small speci¬
men from the cabinet of E. Jewett: specimens from Buffalo, N.Y., are some-
LOWER HELDERBERG PERIOD.
255
times six inches or more in length. Species also occur in this rock belonging
to the allied genus Pteryyotus (fig. 440 is a foreign species), and to the Phyllo-
pod genus Ceratiocaris, both of which
genera were first described in England.
The latter has some resemblance to fig.
262 A. Fig. 434, Leperditia alta, an
Ostracoid, abundant in the Water-lime.
The following is a list of the charac¬
teristic species of the subdivisions:—
1. Water-lime.—Merista sulcata,Avi-
cula ruyosa, Leperditia alta, Tentacu-
lites ornatus.
2. Lower Pentamerus.—Apiocystis
Gebhardi, Rhynchonella semiplicata,
Pentamerus galeatus, Euomphalus ?pro¬
fundus.
3. Catskill Shaly Limestone.—Stro-
phomena radiata, S. punct.ulifera, Me¬
rista levis, Eatonia sinyidaris, Sp>irifer
macropleurus, Sp. perlamellosus (for¬
merly ruyosus), Platyceras vcntricosum,
Dalmania pleuroptyx H. (formerly D.
Hausmanni).
4. Upper Pentamerus.—Pentamerus pseudo-yaleatus, Rhynchonella ventricosa,
R. nobilis, Spirifer concinnus.
Atrypa reticularis and Strophomena rugosa are among the few species of the
Niagara period which occur in the rocks of the Lower Helderberg.
In Perry co., Tennessee, there is apparently a mingling of the fossils of the
Niagara and Lower Helderberg periods in a single thin layer, and it has net yet
been found easy to separate them into the two periods.
It is quite possible that in the interior of the Mississippi basin
many of the Niagara species were continued into the Lower Hel¬
derberg period.
III. General Observations.
Geography.—In the Salina period, as already explained, the
limestone-making seas of the Niagara period in New York had
been succeeded by a great range of muddy flats and shallow basins ;
and in the West the basin had apparently become much contracted
in area, judging from the limited extent of Salina limestones.
Neither of these formations reaches to eastern New York.
In the Lower Helderberg period, which succeeds, there was a
return of the conditions for making limestones ; but, in striking
contrast with the formations that preceded, the beds have their
greatest thickness in eastern New York, and none occur in western.
Figs. 431-434.
Crustaceans. — Fig. 433, Eury-
IM ptenis remipes, a small speci¬
men ; 434, Leperditia alta, na-
Tentaculites turai
size.
ornatus.
256
PALAEOZOIC TIME —UPPER SILURIAN.
Here, then, a new phase in American geography is brought out to
view. The Lower Helderberg limestones are mainly Appalachian
formations; for even the New York part is directly in the range
of the Appalachians of Pennsylvania. It is worthy of note that
this limestone formation of the last period of the Upper Silurian
is the first one that was produced over the Appalachian region
after the Trenton in the middle of the Lower Silurian. But the
Trenton beds spread over both East and West, while the Lower
Helderberg occur only sparingly in the West; and in this the two
periods are in contrast, the older formation having the widest dis¬
tribution.
The sinking of eastern New York which was required for the
formation of the Lower Helderberg limestones probably submerged,
wholly or in part, the Green Mountain region, which appears to
have been dry land in the Niagara period. That it affected the rest
of the Appalachian region to the southwest is manifest from the dis¬
tribution of the rocks in that direction. Outside of the limestone-
making seas in face of the Atlantic waves there were probably bar¬
riers of sand thrown up by the sea, or of emerged land, repeating
in this respect the condition in the Trenton period. It is true that
limestone reefs may and do form on an exposed coast; but only in
case the submerged bottom of the continental border (which at this
time was over 100 miles wide) was not so near the surface that its
sands or mud could be thrown over the growing reefs by the waves
or currents. Limestones have been made for the most part from
the relics of species that require clear water, like the coral lime¬
stones of existing seas. So great a breadth of shallow border as that
of the American coast could hardly have existed at the time with¬
out sand-reefs being thrown up to fend off the waves, unless the
whole were deeply submerged.
OBSERVATIONS ON THE AMERICAN UPPER SILURIAN.
General features.—Fresh-water lakes and rivers, fresh-water de¬
posits, and land or fresh-water animal life, continue unknown
through the American records of the Upper Silurian, as thus far
investigated. Such rivers and lakes probably existed, as it is cer¬
tain there was dry land ; but they have left nothing that survived
subsequent changes. It is barely possible that some of the Mol-
lusks may have lived in fresh waters ; but the remains are so mingled
with species that are obviously salt-water types that it cannot be
proved to be true of any.
With regard to land-plants there is some doubt. Certain sub-
UPPER SILURIAN.
257
cylindrical fossils found in the island of Anticosti (p. 231) have
been referred to plants and named Beatricea. Similar fossils occur
also in Kentucky. But the ambiguous character of the fossils,
their occurrence in limestone, and the non-occurrence of any land-
plants in the marls—originally marshes—of the Salina period,
make their vegetable nature very doubtful. It is not impossible
that leaves and stems of true land-plants may yet be found ; but
it is very remarkable that, if existing, the beds of shale and ar¬
gillaceous sandstone should have been so extensively explored
without finding them.
Conditions of the Continent.—The survey of the successive
formations of the Upper Silurian teaches that the geological
changes in progress were, like those of the earlier Silurian, of con¬
tinental extent. The causes in action were not making a mere
edging to the continent, as in Tertiary times, but were building
up the very continent itself by wide-spread accumulations of lime¬
stone, sands, and clays.
Moreover, the continental seas were not the ocean's bed. In
many of the epochs, the ripple-marks and cracks from sun-drying
prove the shallowness of the water over great regions and a wide
expanse of exposed beaches and marshes in others. The corals
and the profusion of marine life in the limestones are also proofs
of shallow waters. No greater depth than 500 feet is indicated
by any of the species ; and as corals were probably limited then,
as now, to within twenty fathoms of the surface,—-for they can
make solid limestones only where the waves can help them,—the
continental seas must have been to a considerable extent much
less deep.
The continental areas still included little permanent dry land.
The continent had enlarged somewhat since the Azoic age; but the
greater part of the United States was yet to be completed by the
deposition of the Devonian, Carboniferous, and later beds.
Contrast between the Interior and the Appalachian regions.
—The shales and sandstones which prevail in the East from the
vicinity of the Azoic of New York southwest along the Appala¬
chian region are mostly wanting in the West, where the Niagara
limestone is widely distributed. In some places on the north
there is a limestone of the Salina period. The West was there¬
fore in certain parts still making limestones while the East inter¬
posed between its limestones extensive clay and sand deposits.
The limestones of the West prove slight changes of level there ; the
argillaceous beds and sandstones of the East, great oscillations
over the Appalachian region; and in the Niagara period they
18
258
PALAEOZOIC TIME UPPER SILURIAN.
amounted in Pennsylvania to at least 500 feet in the Oneida
epoch, 1500 feet in the Medina, over 2000 feet in the Clinton, 1500
feet in the Niagara and Salina, and 500 in the Lower Ilelderberg,—
in all 0000 feet. In the Salina period, the subsiding area stretched
up into New York west of its centre; for it was there that the
Salina beds were formed to a thickness of 1000 feet.
Life.—(«.) General features.—The range of animal life was in
its grander divisions the same as in the later part of the Lower
Silurian. The highest species continued to be the Cephalopods,—
the first among Mollusks, and that group among Invertebrates
that more than any other embraced characters of the Vertebrates;
for example, perfect organs of sight, hearing, and touch, great size
and strength, and powerful arms for prehension. The Crustaceans
belong to a higher type,—the Articulate,—but only to the lower
division of that type. The Vertebrates are yet unknown among
American Silurian fossils.
While the grand types remained the same, there were changes
through the disappearance of many genera and families and the
introduction of others.
(b.). Radiates.—The group of Graptolites, which passed its climax
in the Lower Silurian, had its last species in the Clinton epoch of
the Upper Silurian. Crinideans were brought out in many new
genera and an increasing number of species. Corals became much
more varied ; the Chain-corals (Halysitcs) were common, but passed
away with the Upper Silurian ; the Favosites and the Cyathophyl-
loids also increase in abundance, and abound still later in the
Devonian.
(c.) Mollusks.—Mollusks—the dominant type of the seas—are
most abundantly represented by Brachiopods. Among them, the
genera Spirifer, Athyris, Chonetes, and others, were added to Lin-
gula, Orthis, Leptcena, Rhynchonella, Atrypa, etc. of the Lower Silu¬
rian : at the same time, Orthis had lost its pre-eminence, and was
of few species. The Lower Silurian Brachiopods have no bony
arm-supports internally, excepting the very short ones in Rhyncho¬
nella. In both Spirifer and Atrypa these supports were long and
rolled spirally. The genus Spirifer commences with narrow spe¬
cies, little broader than high, but in the later part of the Upper
Silurian they are already much wider (fig. 429), though not as
extravagantly so as in many of the s'pecies in the Devonian and
Carboniferous ages.
The Conchifers and Gasteropods are few compared with the
Brachiopods ; and in both groups the species are mostly siphon-
less ; that is, the Gasteropods have the aperture without a beak,
UPPER SILURIAN.
259
and the Conchifers, with the exception of the Cardium family, have
the pallial impression entire (fig. 1G3). The species of Conchifers are
mostly of the Mytilus, Avicula, Area, and Cardium families ; those of
the Gasteropods, mainly of the Bellerophon and Trochus families.
The Tcntacidites have their climax in the Upper Silurian, occurring
in great numbers in some of the rocks ; after this they are compa¬
ratively rare. Among Cephalopods, the Orthocerata, while common,
are not so large nor so numerous as in the Lower Silurian.
The genus Ormoceras—with large beaded siphuncle—-ceases with
the Niagara period. Both the straight and the curved or coiled
shells have the partitions simply arched, and not plicate as in
after-time. The Conularice are more numerous and larger than
before.
(d.) Articulates.—The sub-kingdom of Articulates still embraces
only the water-types of Worms and Crustaceans. Trilobites are
multiplied in genera,—Homalonotus and Fhacops being added to
Calymene, Agnostus, Asaphus, Illaenus, IAchas, Acidaspis, and Dalmania
of the Lower Silurian. The bivalve Crustaceans, or Ostracoids, are
very common. In the Eurypterus (fig. 433) there is a new step in
the development of the Crustacean type, yet one still within the
lowest order, that of Entomostracans. It was observed, p. 203,
that Trilobites and Phyllopods were comprehensive types,—that is,
types embracing features of other unexpressed groups of Crusta¬
ceans, and not typical Entomostracans. The Ostracoids, also, are a
peculiar group, and have a close resemblance in general structure
to the young of a tribe that appears long afterwards,—the one
including the Cirripeds (Barnacles and Anatifas, p. 154). With the
Eurypterus commences the typical Entomostracan. It belongs to
the same general group with the Cyclops and Sapphirina,— the
Qyclopouls,—the largest tribe in the order of Entomostracans.
(<?.) Extinction of species.—The number of Upper Silurian species
thus far described from the American rocks is about G80, which is
at least 200 short of the number existing in collections. Not a
species existed in the later half of the Upper Silurian that was
alive in the later half of the Lower Silurian. Less than a dozen
species are continued into the Devonian, and these disappear long
before the close of that age.
(/.) Genera of existing seas.—To the list of existing genera no
additions are made in the course of the Upper Silurian. All but
the few before enumerated, I Any via, Disci na, Nautilus, Ilhynchonella,
Plcurotomaria, and Crania, become extinct.
Climate.—There is no evidence that the climate of America
260
PAL/EOZOIC TIME 1
•UPPER SILURIAN.
included frigid winds or seas. The living species in the waters
between the parallels of 30° and 45° were in part the same, or
closely related in species, with those that flourished between the
parallels of 65° and 80°. (See pages 238 and 242.) From this life-
thermometer we learn only of warm or temperate seas.
FOREIGN UPPER SILURIAN.
The rocks of the Upper Silurian are widely distributed over the
globe, though less universal than those of the lower Silurian. They
occur in Great Britain, Scandinavia, Russia, Germany, Sardinia, and
Bohemia, but have not been identified in France or Spain : also in
Asia, Africa, and Australia. Throughout, they sustain the prin¬
ciple that the earlier formations are in general of continental
range. They seem on a geological map to cover but small areas,
but only because they are concealed by later formations: they lie
underneath.
The table on page 168 exhibits some of the foreign equivalents of the Ameri¬
can Upper Silurian.
The equivalents of the Niagara period in Great Britain are (1) the Lower
Llandovery beds of South Wales (especially near Llandovery), supposed to
correspond to the Medina group; (2) the Upper Llandovery of Shropshire and
other localities (including the May Hill sandstone), corresponding to the Clinton
group; (3) the Wenlock group (divided into the Lower Wenloek or Woolhope
limestone, the Wenlock shale, and the Upper Wenlock or Dudley limestone),
corresponding to the Niagara limestone. The Ludlow group (4) (consisting of
the Lower Ludlow rocks, the Aymestry limestone and the Upper Ludlow) is re¬
garded as corresponding to the Lower Helderberg.
The largest Upper Silurian area in Great Britain is situated near the borders
of Wales and England, where are the May Hill sandstones, the Wenlock or Dud¬
ley limestone and shales, and the Ludlow argillaceous sandstones and shales, in
which lies the Aymestry limestone. Another area is in northern England, on
the west side, where are the Coniston grits, the Ireleth slates equivalent of the
Wenlock, and the Kendal tilestones equivalents of the Upper Ludlow. There are
other areas in southern Scotland and Ireland. The thickness of the British Upper
Silurian is about 6000 feet.*
In Scandinavia, the limestones and sandstones of Gothland represent the
Niagara, and the Calciferous flags and Upper Malmo group the Upper Helder¬
berg. In Bohemia, the Upper Silurian rocks are limestones and schists of Bar-
rande's formations E, F, G, H.
* The student desiring information on the Silurian of. England will find the
subject displayed with great fulness in Murchison's Siluria, the second edition of
which appeared in England in 1859. The work also gives the best digest that
has been made of the facts relating to the Silurian and other Palaeozoic formations
of Europe.
FOREIGN UPPER SILURIAN.
261
The following tables show the distribution in other countries of some species
»f the Niagara and Lower Helderberg periods.
1. American Niagara Species occurring elsewhere.
Halysites catemilata, Great Britain (Llandeilo, Dudley, Aymestry), Norway,
Sweden, Russia, Eifel.
Heliolites pyriformis, Great Britain (Wenlock, Aymestry), France, Sweden,
Russia, Eifel.
Stromatoj)ora coneentrica, Great Britain (Dudley), Sweden, Russia, Eifel.
Limaria fruticosa, Great Britain (Dudley, Aymestry), Russia.
Limaria clathrata (?), Great Britain (Dudley), Russia.
Ichthyocrinus levis (?), Great Britain (Dudley).
Eucalyptocrinus decorus, Great Britain (Dudley).
Orthis elegantula, Great Britain (Wenlock), Gothland (in Sweden).
Orthis hybrida, Great Britain.
Orthis biloba, Great Britain (Dudley), Gothland.
Orthis Flabellulum, Great Britain (Bala).
Leptsena trausversalis, Great Britain, Gothland.
Strophomena rugosa (formerly Leptsena depressa), Great Britain (Dudley, Ay¬
mestry), Sweden, Russia, Belgium, Eifel, France, Spain.
Spirifer crispus, Great Britain (Llandeilo, Dudley), Gothland.
Spirifer radiatus, Great Britain (Dudley).
Spirifer sulcatus {?), Great Britain (Dudley).
Atrypa reticularis, Great Britain (Wenlock), Gothland, Germany, Russia
(Urals, Altai).
Merista (Rliynchonella) nitida, Great Britain, Gothland.
Rhynchonella bidentata, Great Britain (Wenlock).
Rhynchonella cuneata, Great Britain (Wenlock), Gothland.
Rhynchonella plicatella, Great Britain (Wenlock, Aymestry).
Rhynchospira ? (Atrypa) aprinis, Russia.
Pentamerus brevirostris, Great Britain.
Pentameru8 interplicatus, Great Britain.
Orthoceras implicatum, Great Britain (Ludlow), Gothland.
Orthoceras virgatum, Great Britain.
Orthoceras undulatum, Great Britain, Eifel.
Illsenus (Bumastis) Barriensis, Great Britain (Dudley).
Phacops limulurus (?), Great Britain (Dudley), Bohemia, Sweden.
Ceraurus insignis, Bohemia.
CalymeneBlumenbachii, Great Britain (Bala, Wenlock), Sweden, Norway, Bo¬
hemia, France.
Homalonotus delphinocephalus, Great Britain (Dudley).
Proetus Stokesii, Great Britain (Dudley).
2. American Lower Helderberg Species occurring elsewhere.
Strophomena rugosa, Great Britain (Dudley, Aymestry), Gothland, Russia, Eifel,
France, Spain.
262
PALAEOZOIC TIME—UPPER SILURIAN.
Atrypa reticularis, Great Britain (Wenlock), Sweden, Russia (Urals, Altai),
Bohemia.
Dalmania nasuta, Great Britain, Sweden, Russia.
Eurypterus remipes, Russia (island of Oesel, according to Keyserling).
Pentamerus galeatus, Great Britain (Aymest.ry, Dudley, Ludlow), Eifel.
There are a number of other species closely like European, but they are
regarded by Hall as distinct.
3. Arctic American TJpper Silurian Species occurring elsewhere.
Halysites catenulata, Great Britain, Norway, Sweden, Russia, U.S.
Favosites Gotlilandica, Great Britain, Sweden, U.S.
Favosites polymorpha, Great Britain, France, Belgium, Eifel.
Stromatopora cuncentrica, Great Britain, Eifel.
Receptaeulites Neptuni Do France, Great Britain, Belgium, Eifel, U.S.
Orthis eleyantula, Great Britain, Gothland, Russia, U.S.
Atrypa reticularis, Great Britain, Gothland, Urals, Altai in Siberia, U.S.
Pentamerus Conchidium Dalman, Gothland.
Rhynchonella sublepida ? De Verneuil, Urals.
Encrinnrus levis ? Angelin, Gothland.
Leperditia Baltica Hisinger, Gothland.
There are a considerable number of species in the British Lower Silurian
which pass into the Upper Silurian. They are found mingled in the inter¬
mediate Llandovery formations, which, although classed with the Upper Silurian,
contain between 40 and 50 species that occur also below.
Barrande has found nearly 2000 species of fossils in the Bohemian Silurian
basin above the Primordial strata. The limestone E abounds in organic re¬
mains, and among them are 400 species of Cephalopods, and 78 species of Tri-
lobites (of the genera Calymene, Acidaspis, Cheirurus, Cyphaspis, Liclias, Phacops,
Harpes, Rrontens, and Proetus). Barrande regards this as the culminating period
for the Trilobite race. Limestone F also contains 75 species of Trilobites, and of
the same genera, associated with a profusion of Brachiopods. In G there are
many Goniatites and other species, which show that, while the strata are inti¬
mately connected with E and F physically and in their fossils, the period
probably corresponds in part with the early Devonian. Besides 40 species
of Trilobites of the above genera, there are others of the Devonian genus
Dalmania. In Bohemia 57 Lower Silurian species pass into the Upper
Silurian.
A list of the genera common to the American and European
continents would show almost a complete identity, and the same
system of progress from the Lower Silurian onward. In each, the
genera Spirifer and Chonetes, among the Brachiopods, were added to
Orthis, Leptccna, and Atrypa; Halysites (Chain-corals), Favosites, and
Cyathophyllidce became abundant; Crinoids were greatly multiplied ;
and the Eurypterus group or Cyclopoid Crustaceans commenced a
FOREIGN UPPER SILURIAN.
263
new line among the Articulates; while Graptolites, so common in
the Lower Silurian, were few in species and numbers, and finally
became extinct before the close of the era.
There was thus a uniformity of life in the New and Old World.
Similar genera made their appearance, and others their exit. In
neither have we any evidence that the progress had reached to the
introduction of land or fresh-water species of animals ; and no relic
of a land-plant has yet been discovered in the Silurian strata of
Europe or Britain, except in the uppermost beds (page 264).
The following figures illustrate some of the British Upper Silurian species
not yet found in America.
Figs. 4.15-440.
Fig.435, a, Omphyma turbinata; 436, Cystiphyilum Siluriense; 437, Crotaloerinus rugosus;
438, Pentamerus Knightii; 439, Grammysia cingulata: 440, a, Pterygotus bilobus.
Fig. 436 is the Cyathophylloid coral Cystiphyilum Siluriense ; fig. 435, another,
Omphyma turbinata, reduced one-half in size; fig. 437, Crotaloerinus rugosus.—
264
PALAEOZOIC TIME UPPER SILURIAN.
all three of the Wenlock; 438, the Pentamerua Knightii of the Aymestry lime¬
stone; 439, Grammyaia cingulata of Dudley; 440, the Pterygotus bilobus, related
to the Eurypterus,—a genus some of whose species, according to Salter, were
seven or eight feet long, exceeding modern Crustaceans by several feet.. It is
an early lesson taught by science, that size, however important in some parts
of the system of nature, is no necessary criterion of rank.
On some shells traces of the original colors still remain, proving
that there was beauty of coloring in Silurian times as well as now,
and also that the species lived in comparatively shallow waters.
Professor Forbes has stated that colors arranged in figures are not
found on shells which live below a depth of fifty fathoms.
Notwithstanding the striking coincidences in species and still more in genera
between the New and Old World, there are discrepancies which make it quite
difficult to determine with precision the equivalency of the rocks. The Wenlock
beds contain some 40 Niagara species; and still there are quite a number
(among them Dalmania Hau&manni and Pentamerua galeatus) that are closely
related to species found in the period of the Lower Helderberg. The Ludlow
beds are related similarly to the Lower Helderberg, and still some species occur
in them that in America exist only in the Devonian. This is so striking a fact
that the Ludlow is generally regarded as extending into the Devonian,—the
American records in this being the assumed standard. Mr. Hall takes this
ground.
The group of Cyathophylloid corals is much more largely de¬
veloped in the Ludlow beds than in the American Silurian ; for the
coral-reef period in America is that of the Upper Helderberg in
the Lower Devonian. Besides, there is the higher group of Fishes,
the first of the Vertebrates, some relics of which occur in the upper
layers of the Ludlow beds. These remains are of the genera Cepha-
laspis, Onchus, and Plectrodus: the first belongs to the tribe of Gan¬
oids, and the other two to that of the Selachians or Sharks. In
the same Ludlow beds, traces of land-plants have been found, in
the shape of minute globular bodies which have been regarded as
the seed-vessels of some species of the Lycopodium tribe of plants.
The upper part of the Silurian beds in Bohemia has also afforded
fish-remains of similar character to those of the Ludlow beds.
If the Ludlow beds be divided and the upper part referred to the
Devonian, then these species of fishes and the associated land-plants
will come into that age,—the Age of Fishes.
Still, if fossil fishes should hereafter be found even lower in the
Silurian, it will harmonize entirely with the system in other parts
of the geological series. As has been stated on p. 126, we naturally
look for precursors of every Age. There were Mammals before the
age of Mammals, Reptiles before the age of Reptiles, Acrogens and
DEVONIAN AGE.
265
Gymnosperms before the age of Coal-plants; and so there may have
been Fishes precursors of the age of Fishes. This is consonant with
the principles involved in the very nature of history.
European geology, as far as developed, sustains the conclusions
deduced from the American:—that the Upper Silurian era, to its
close (with the exception above mentioned, if it be such), was an
era of small areas of dry land,—of continents mostly submerged,
though not necessarily at great depths,—of warm waters to the
poles,—of marine life,—of Mollusks and inferior Crustaceans as the
higher life of the seas, and the flower-like Corals and Crinoids as the
inferior life, and of Searweeds as the vegetation.
AGE OF FISHES, OR DEVONIAN AGE.
The Devonian formation was so named by Murcliison and Sedg¬
wick from Devonshire, England, where it occurs and abounds in
organic remains. Both in America and other countries the beds
pass into those of the Silurian by an easy transition. Yet they still
mark a new epoch in the progress of life, and thus stand apart in
the system of geological history.
The periods and epochs in the American Devonian, as deduced
from the series of rocks laid down by the New York geologists, are
as follow:—
5. Catskill Period (12) Catskill Red Sandstone (12).
4. Chemung Period (11) j 2' C1lemun9 epoch-Chemung group (11 6).
( 1. Portage epoch—Portage group (11 a).
c 3. Genesee epoch—Genesee beds (10 e).
3. Hamilton Period (10).... •! 2. Hamilton epoch—Hamilton group (10 6).
11. Marcellus epoch—Marcellus group (10 a).
|- 3. Upper Helderherg epoch—Upper Helderberg
2. Corniferous Period (9). J SrouP (9 c)*
2. Schoharie epoch—Schoharie grit (9 6).
• 1. Cauda-Galli epoch—Cauda-Galli grit (9 a).
1. Oriskany Period (8) Oriskany sandstone.
The formations of the first and second periods are sometimes
designated the Lower Devonian, and those of the third, fourth, and
fifth periods, the Upper Devonian. The Corniferous period was the
great limestone-making period of the Devonian age in America.
The rocks of the succeeding periods (Upper Devonian) are mostly
shales or sandstones, with only subordinate layers of limestone.
266
PALAEOZOIC TIME—DEVONIAN AGE.
1. ORISKANY PERIOD (8).
I. Rocks: kinds and distribution.
The Oriskany sandstone is named from the town of Oriskany, in
Oneida co., N.Y., one of its localities. The rocks are mostly rough
sandstones. They are 30 feet thick in this region, and thin out both
to the east and west, being barely recognizable on the Hudson, and
to the west extending as far as Cayuga Lake. West of the Appa¬
lachians, beyond New York, the formation is for the most part un¬
known ; but along the Appalachian region it stretches south through
Pennsylvania, Maryland, and Virginia, having a thickness of several
hundred feet, and retaining its rough aspect; and it also occurs to
the north at Gaspe, near the Gulf of St. Lawrence. In the Eastern
border region, the formation has been identified by its fossils in
Maine between Parlin Pond and the Aroostook River, and else¬
where ; also in Nova Scotia.
The sandstone consists either of pure siliceous sands, or of argillaceous
sands. In the former case it is usually yellowish or bluish, and sometimes
crumbles into sand suitable for making glass. The argillaceous sandstone is of
a dark brown or reddish color, and was once evidently a sandy or pebbly mud.
In some places it contains nodules of hornstone. The beds are often distin¬
guished by their rough and hard dirty look (especially after weathering) and
the large coarse calcareous fossil shells,—species of Brachiopods. The sandstone
occurs in Cayuga co., Canada West, and also on the Mississippi in Illinois. In
St. Genevieve co., Missouri, the rock is a limestone (Shumard).
The Nova Scotia strata of this epoch occur at Nictaux and on Moose and
Bear Rivers. They include a thick band of fossiliferous iron-ore, which is an
argillaceous deposit at Nictaux, but, owing to partial metamorphism, is a
magnetic iron-ore on Moose River.
n. Life.
1. Plants.
No remains of land-plants have been yet observed. Considering
the nature of the rock, the negative evidence bears strongly against
the existence of land-vegetation in the Oriskany period.
The rocks of Gasp6, according to Dawson, contain relics of Coniferous wood
and other plants, and are pronounced to be probably Lower Devonian; but the
particular period to which they belong is not known. They are mentioned beyond,
under the Hamilton period. According to the same author, remains of land-
plants occur in a limestone at Gasp6, which " seem," he observes, " to indicate
the occurrence of Psilopftyton and Noeggerathia or Cordaitei in the Upper Silu¬
rian of Canada."
ORISKANY PERIOD.
267
2. Animals.
The most common species are the coarse Spirifer arenosus (fig. 442),
and the Rensselaeria ovoides (fig. 444). The rock is often made up
Figs. 442-444.
Brachiopods.—Figs. 442, 443, Spirifer arenosus,444, Rensselaeria ovoides.
of these large fossil shells crowded together, or contains their casts
with the cavities the shells once occupied. Fig. 443 represents a
cast of the interior of Spirifer arenosus.
In New York, the fossils include Brachiopods (which are the most numerous
species), Conchifers, Gasteropoda, Cepihalopoda (Orthocerata, etc.), and Trilobites,
and only traces of Crinoids. In Maryland, according to Hall, there are a number
of fine Crinoids of the genera Mariacrinus, Edriocrinus, and others, besides three
species of Cysti deans, and among them one of the peculiar genus Anomalocystis
(allied to fig. 418). Among the Gasteropods of the same region there are great
numbers of shells of the genus Platyceras,—a thin conical shell having the top
rolled to one side (like fig. 458), related apparently to Janthina of our seas. In
some places in Maryland and Virginia, they occur packed crowdedly together in
a soft sand-rock, the sands of which are hardly more coherent than those of a
sea-beach (Hall). This rock contains a wonderful profusion of shells, although
the number of species is small. The ribs of some of the Spirifers have a pecu¬
liarity observed in only one American Silurian species (of the Niagara epoch),
but in Europe not known before the Devonian age,—which is, that they subdivide
dichotomously, instead of being simple.
The shell in the genus Rensselaeria Hall, contains a loop-liko arm-support, a
little like that in Terehratula, but it is only curved, instead of bent, and has a
spade-shape termination.
268
PALAEOZOIC TIME—DEVONIAN AGE.
HI. General Observations.
The Oriskany sandstone is another of the arenaceous rocks ranging
from central New York to the southwest along the Appalachian
region, and thus serving to define the old Appalachian sand-reef.
This it does not only to the south, but also to the northeast at
Gaspe. As in other cases, the rock thickens on going from New
York to the southward, showing less depth of water and less change
of level, or subsidence towards the Azoic, than in the opposite
direction. The limits of the formation in the State of New York,
and its fossils also, seem to point to the existence at this epoch of a
sheltered bay opening to the southeast,—such a New York bay as
might have existed if the Green Mountain region (as before in the
Upper Silurian era) were raised a dozen feet or more out of water,
and if also the Azoic of northern New Jersey (see p. 137), the proper
continuation of the Green Mountains, were an island or reef in the
sea. The muddy and sandy bottom of the bay would have given
the shells a fit place for growth. To the south, as the fossils in
Maryland and beyond show, the accumulations were those of an
open bay or coast, where there were at least purer waters.
The thickness of the formation along the Appalachian region
indicates a continuation of the series of subsidences that began far
back in the Silurian or before. We may hence conclude that the
Green Mountain region was a narrow island lying between seas
covering more or less of New England and New York, and bounded
by the St. Lawrence channel on the north ; for there is no reason
to doubt that Devonian as well as Carboniferous strata occur among
the now crystalline rocks of New England. The region of Appa¬
lachian subsidence, instead of including the Green Mountains, as
in the early Lower Silurian era, extended northward, in the direct
line of the Alleghanies, over the southern half of central New
York, as in parts of the Upper Silurian; for this is indicated by
the position of the sandstone.
The Oriskany period, taking into view the whole range of its life, is more
closely related, as Hall states, to the last period of the Silurian than to the
following Devonian ; but in its more common Brachiopods it has rather a De¬
vonian character. It was fixed upon as the beginning of the American Devonian
by the eminent French geologist M. de Verneuil. There is, however, a more
complete change in the American fauna after the Oriskany period than before
it: for this reason, and on account of the relations of its fossils to those of the
Lower Helderberg, Hall suggests the query whether the Devonian age would
not more properly commence with the next or Corniferous period.
CORNIFEROUS PERIOD.
269
2. CORNIFEROUS PERIOD (9).
Epochs.—1. Cauda-galli, or that of the Cauda-galli grit (9 a);
2. Schoharie, or that of the Schoharie grit (9 b); 3. Upper Hkldeb-
berg, or that of the Onondaga and Corniferous limestones (9 c).
I. Rocks : kinds and distribution.
1. Cauda-galli Epoch.
The term Cauda-galli refers to the feathery forms of an abundant
fossil supposed to be the impressions of a sea-weed (fig. 441). The
rock is a drab or brownish argillaceous sandstone, often shaly and
crumbling. It rests upon the Oriskany sandstone, but its position
is somewhat more easterly, it lying altogether east of the west limit
of Oneida co., N.Y., and thickening towards the Hudson.
In the Helderberg Mountains, south of Albany, the thickness is 50 or 60 feet.
It extends southerly, and has been observed in Sussex co., New Jersey, and on
the eastern border of Pennsylvania, with its characteristic Cauda-galli fossil.
2. Schoharie Epoch.
The Schoharie grit is a fine-grained calcareous sandstone, contain¬
ing numerous fossils. The lime becomes dissolved out on exposure,"
leaving a rusty rock full of casts of the fossils and holes left by the
removed shells. In New York the beds are confined to the eastern
part of the State. It resembles the Oriskany sandstone, but has
very different fossils.
3. Upper IIelderberg Epoch.
The rocks of the Upper IIelderberg epoch are limestones. They
spread widely over the Interior Continental basin from eastern New
York to the States beyond the Mississippi.
The formation in New York is divided into the Onondaga lime¬
stone (the lower part) and the Corniferous limestone (the upper).
The latter contains disseminated masses of hornstone (or imperfect
flint), lying in layers of the limestone between other layers that con¬
tain little or no hornstone (just as the flint lies in the chalk-bed);
and hence the name corniferous (from the Latin cornu, horn). The
thickness of the whole series of strata is in some places 350 feet.
The color of the limestone is dark grayish and occasionally black in New
York, and light gray, drab, and buff in the Mississippi basin.
(a.)Inlerior Continental haxin.—In New York the beds have a thickness seldom
over 20 feet for the Onondaga limestone and 50 feet for the Corniferous. The
270
PALAEOZOIC TIME DEVONIAN ACE.
formation has been recognized in Ohio, along the shores of Lake Eric, in Michi¬
gan, Indiana, Illinois, Kentucky, Wisconsin, Iowa, Missouri, and other parts
of the Mississippi basin, but the subdivisions above mentioned are not distin¬
guishable. In the Michigan peninsula the thickness is 354 feet (Wincliell); in
Iowa, 50 to 60 feet (Hall); in Missouri, from a few feet to 75. The rocks are
finely displayed at the Falls of the Ohio, near Louisville, Ky., and are as full
of fossil corals as any modern coral reef.
The upper layers of the rock in New York, which are usually dark grayish,
are nearly black on the Niagara. In some localities west of New York the rock
is oolitic. In Missouri, siliceous and sandstone layers alternate with the lime¬
stone. The hornstone of the Corniferous beds is often left in rough projecting
masses where the limestone portion has been worn away by the action of
water. These rocks outcrop also in southwestern Canada, N. of Lake Erie.
(6.) Appalachian region.—The Upper Ilelderberg formation has not been ob¬
served among the rocks of Pennsylvania except northwest of the Kittatinny
Mountain, between the Delaware and Lehigh Rivers.
(c.) Eastern border region.—At Owl's Head, on Lake Mcmphremagog, near the
northern borders of Vermont, there is a true coral-reef rock, full of corals, over¬
laid by talcose schist; and, although partially inetamorphic, many of the speci¬
mens of fossils are tolerably perfect. Among the species, Billings has recog¬
nized Syringopora Hiningeri B., Favositex basaltica Goldfuss, Diphyplnjllum
etramineum B., and Zaphrentis gigantca Lesueur. Besides these, according to
Hitchcock, Atrypa reticularis has been identified by Hall. To the south, in
Massachusetts, at Bernardston (west of the Connecticut, and not far from
Greenfield), there is also a metamorphic limestone of this epoch, with fossils (C.
H. Hitchcock). It is altogether probable that Devonian beds stretch south from
Lake Meniphremagog; for the rocks have this strike through the whole length
of the State (and through New England generally); and the limestone may be
represented among them,—perhaps in the Calciferous mica schist, which Hunt
has suggested may be a metamorphic limestone. It is also supposed that the
Upper Ilelderberg limestone occurs south of the St. Lawrence, between Vermont
and Gasp6.
H. Life.
I. Plants.
The plants thus far observed are sea-weeds and Protophytes. No
land-plants of the period are known. Fig. 441 represents the
" Cauda-Galli" sea-weed characteristic of the first epoch.
The protophytes occur in the hornstone of the Corniferous lime¬
stone, and appear to be very abundant throughout it. The dis¬
coveries were made, but a few days before these pages were printed,
by Dr. M. C. White, of New Haven. Through his investigations,
and others, since made, by F. H. Bradley, it is now known that
organisms similar to those figured below (fig. 441 A) are common
to the hornstone of both older and later Palaeozoic periods. The
CORNIFEROUS PERIOD.
271
facts show that hornstone is analogous to flint in origin as well as
in its mode of occurrence: the two are the same in composition
Fig. 441.
Fucoides Cauda-Galli
(page 55). Figs. 441 A a-d represent the sporangia (spore-capsules,
or receptacles containing the germinative cells) of Desmidiese, or
Fig. 441 A.
Microscopic Organisms in IIornstone.—Figs, a-i and l-n, Protophytes; j,Jc, Spiculaof
Sponges; o, p, fragments of dental apparatus of Gasteropoda.
Desmids,— closely resembling organisms from flint called Xan-
thidia by Ehrenberg;—e, a Desmid having the usual division into
halves ; f, g, Desmids consisting of several cells; i, a Diatom:—
figures magnified about 225 diameters. The sizes of the specimens
figured vary from l-500th to l-5000th of an inch: diameter of
fig. a, l-500th in.; of d, e, l-1500th ; of i, l-1000th ; of cells in f, g,
l-7000th by l-5000th. Desmids, like the Diatoms, are microscopic
plants, consisting of one or a few cells; but they secrete little or
no silica, and have a pale-green color. The hornstone also contains
numerous rhombic crystals, probably of calcite, from l-500th to
l-1000th inch in diameter.
272
PALAEOZOIC TIME—DEVONIAN AGE.
2. Animals.
The Upper Iielderberg period is eminently the coral-reef period
of the Palaeozoic ages. Many of the rocks abound in corals (see figs.
445-451), and are as truly coral reefs as the modern reefs of the
Pacific. The corals are sometimes standing in the rocks in the
position they had when growing ; others are lying in fragments as
they were broken and heaped up by the waves; and others were
reduced to a compact limestone by the finer trituration before con¬
solidation into rock. This compact variety is the most common
kind among the coral-reef rocks of the present seas; and it often
contains but few distinct fossils, although formed in waters that
abounded in life. At the Falls of the Ohio, near Louisville, there is
a magnificent display of the old reef. Hemispherical Favosites five
or six feet in diameter lie there nearly as perfect as when they were
covered with their flower-like polyps ; and, besides these, there ai ^
various branching corals, and a profusion of Cyathophylla, or cup-
corals ; some of the species of the latter (fig. 445) have a breadth of
three inches, and one of six or seven inches; and when alive the
expanded polyp must have had at least this diameter, or, with the
expanded tentacles, probably an inch or two more. These ancient
corals may have had the same rich and varied colors that charac¬
terize the Zoophytes of our own epoch.
There is another point in which the Corniferous period stands out
prominently in American Palaeozoic history. It contains the earliest
remains, thus far discovered, of fishes,—the first of the suh-hingdom of Verte¬
brates. The life of the American seas from this time, therefore, in¬
cluded species of all four sub-kingdoms, Radiates, Mollusks, Articulates,
and the branch now added, Vertebrates.
Among Brachiopods the new genus Productus makes its first ap¬
pearance, one that afterwards in the Carboniferous age became very
common: its earliest species are but half an inch in breadth, while
some of the later are three or four inches. Figs. 228, 229, page 183,
represent different species, but not those of this period.
The hornstone contains spicula of Sponges, two of which are
figured in 441 A j, k; k is magnified 75 diameters. Along with
these, White has detected a fragment of the dental apparatus of a
Gasteropod, represented in fig. o. Fig. p is from a specimen of
this kind observed in hornstone of the Black River limestone
(Trenton period), Watertown, N.Y., by Bradley; Desmids and
spicula of Sponges accompany it. The organic origin of the Palseo-
zoic hornstone can hardly be doubted.
CORNIFEROUS PERIOD.
Characteristic Species.
1. Radiates—(a.) Polyps.—Fig. 445, Zaplirentis gigantea, part of a large
.specimen from the Falls of the Ohio, showing at top the radiate structure, ana
Figs. 445-451.
Polyps.—Fig. 445, Zaplirentis gigantea; 446, Z. Rafinesquii: 417, Phillipeastrea Vernenili.
418, 448 a, Cyatliophyilum rii^osuin ; 440, Favosites Goldfussi; 450, Syringopora Maclurii;
451, Aulopora eornuta.
the depression or fossette in the star on one side; fig. 446, Zapli. Rafinesquii E.
& II., from the Falls of the Ohio, remarkable for the depth of the cell. Another
Cvathophylloid coral of the genus Chonophyllum (0■ magnificum B.) has a dia¬
meter at top of six or seven inches . it is from Wulpole, Canada West. Fig.
447, Phillipsastrea Vernenili E. & H.; fig. 4AS,Cyathophyllitm rugosum, a fragment
from a large mass from the Falls of the Ohio; 448a, section of a cell, showing
the numerous and very thin rays; fig. 449, Favosites Goldfussi D'Orb., from tho
Falls of the Ohio, a fragment of a large specimen; fig. 450, Syringopora Maclurii
B., from Canada West, a coral consisting of a cluster of small tubular cells;
fig. 451, Aulopora eornuta B., from Canada.
(b.) Aealephs.—No species are known, unless, as Agassiz has suggested, tho
Favosites and related corals are of this class (p. 162).
19
274
PALAEOZOIC TIME DEVONIAN AGE.
(c.) Eehinoderms. — There are many species of Crinoids, and the large,
smooth stems of some of them are half an inch to an inch in diameter.
The species of most interest are the Nucleocrini (also
called Olivanitex); they are representatives of the Pen-
tremite family,-—a group which had its first species in
the Chazy, the early part of the Trenton period, in the
liower Silurian, but which from that time appears to have
been extinct until the Corniferous period in the Devo¬
nian. In the Subcarboniferous period it was very com¬
mon. The species of this period are ovoidal, or like
an olive in shape, and have ambulaoral areas closely
like those of the true (pentagonal) Pentremites (figs.
531, 532). Fig. 452 is the Nucleocrinus Vcrneuili. (The
name Nucleocrinus of Conrad antedates Olivanitcs of Troost,
as well as Elseacrinns of Roemer.)
2. Mollusks—(«.) Brachiopods.—Figs. 453 and 454, Spirifer acuminata*
Con. (S. cultrijuyatux Roemer), from New York and the West. Fig. 455, Spirifer
Fig. 452.
Nucleocrinus Ver-
neuili.
Brachiopods.—Figs. 453, 404. Spirifer acuminatus ; 455, Sp. gregarius.
Conchifers.—Fig. 456, Lucina?
rica, Atrypa reticularis, A. imprexxa,
Pentamerus elouyatus Vanuxem ; also
proavia; 457, Conocardium
Stricklandia elonyata (Billings), formerly
a Calccola near C. sandalina (fig. 221),
gregarius, very common in Indiana and Kentucky, at the Falls of the Ohio, and
at Middleton, Canada (Billings). Also, Pentamerus aratus, Chonetes hemisphe-
CORN IFEROUS PERIOD.
275
found in Tennessee; it is a third American genus of the Terebratula family,
—Stricklandia and liensselaeria being the first two. Two small species of Pro-
ductitK have been collected by Billings in Canada, and one by Jewett in the New
York Corniferous.
(6.) Gondiifers.—Fig. 456, Lucina ? proavia,also occurring in Europe ; fig. 457,
Gouocardium trigonale of both New York and the West.
(e.) Pteropnds, Gaxteropods, and Ce¬
phalopoda.— Pteropods are represented
by the Tentaculites scalaiis. There are
also several species of Gasteropods. Fig.
458 is the Platyceras dumosum of the Cor¬
niferous in New York.
A few Orthocerata occur in the beds.
The Cyrtoceras undulatum, a large shell
coiled in a plane, is supposed, as the name
implies, to be related to the Cephalopods.
3. Articulates—Trilobites are the
only Articulates known. The most com¬
mon species are the Dalmania (Odonto-
cephalus) selenurus, having a two-pointed
tail; and the Proetus (Calymenc) craxxi-
marginatus, having the posterior margin of the body (the pygidium) thickened
and rounded.
The Schoharie grit is closely related in its fossils to the limestones above,
and contains but few species that are not found in the latter.
4. Vertebrates.—The remains of the earliest of Vertebrates, Fishes, ap¬
pear first in America, according to present knowledge, in the Schoharie grit ;
and many species are known from the later epoch of the Corniferous period,
both in New York and the more western States of Ohio, Indiana, etc. Some of
these remains are represented in the annexed figures. Fig. 459 is the fin-bone
of a large shark ; fig. 400, the head of a fish related closely to the Pterichthys of
Fig. 459.
Stromness, drawn by Dr. Newberry from a specimen found at Sandusky, Ohio;
and fig. 461, the tooth, natural size, of probably this formidable species. Dr.
Newberry estimates its length at six or seven feet. A specimen was earlier
found by Dr. Norwood at Madison, Indiana, and named by Owen & Norwood
ilacropetalichthys (Am. Jour. Sci. [2] i. 367, 1846). It is near the genus Ho-
moxtius described by Mr. Asmuss, of Dorpat, in 1833 and 1837. As shown in the
figure, the genus differs widely in the sutures of the buckler from Pterichthys
(fig. 516). Asterolepis of Eiehwald has the priority of Pterichthys; but it was
based on a fragment only, and was published without a description.
Fig. 458.
Platyceras dumosum.
276
PALAEOZOIC TIME—DEVONIAN AGE.
There are also among the remains in the Corniferous beds species of Cepha-
laspis resembling the European (fig. 517), and of Holoptychhw (near fig. 518);
but no figures of them have yet been published.
Fig. 460, Head of Macropetalichthys Sullivanti Newberry (X %); 461, Tooth of same.
These earliest of American fishes belong to two out of the three
grand divisions of the class :—
First, the /Selachians, or sharks.
Secondly, the Ganoids, or fishes having the body covered with
shining bony scales or plates. This order of Ganoids, once exceed¬
ingly numerous in species, is now nearly extinct: it is represented
by the Gar-pike and Sturgeon of existing waters.
The third grand division—that of the common osseous fishes, or
Teliosts, which includes the Perch, Salmon, etc.—was not introduced
until near the close of the Eeptilian age, in the Cretaceous period.
The Selachians of the Devonian age belong to the Cestraciont
family of sharks,—a group in which the mouth is furnished with a
pavement of large bony plates instead of teeth, and which have
the first ray of the dorsal fin a large and stout spine (figs. 464, 470).
The Devonian Ganoids are of three kinds: — (1) Placoganoids,
having the body covered with plates instead of scales (like fig. 516);
(2) Bhomlifers, having rhombic scales, and these arranged like tiles
(as in figs. 473, 475, 519) ; and (3) Imbricates,, having the scales ar¬
ranged like shingles, as in Holoptychius (fig. 518) and other Cosla-
canths, and the modern Amia.
All these ancient fishes have vertebrated tails,—that is, the verte¬
bral column extends to the extremity of the tail (figs. 519, 603),
instead of stopping short at its commencement (fig. 473) as in
nearly all existing fishes. In most of these vertebrate-tailed
species the vertebral column extends into the upper lobe of the
tail, and the two lobes are very unequal, as in figs. 464, 519, 617:
Fig. 460.
Fig. 461.
CORNIFEROUS PERIOD.
277
these have been thence called heterocercal fishes, while those
having a tail of the ordinary form, as in fig. 473, are said to be
homocercal.*
* Fishes.—A systematic review of the class of Fishes will make the subject
more intelligible. The relations of Fishes to other Vertebrates are mentioned
on p. 152. Fishes (excluding a few abnormal kinds of the group Dermopteri)
are divided into three orders:—
I. Selachians (or Placoids).—Include the Sharks (figs. 462. 464) and Rays,
having (1) the skeleton cartilaginous; (2) the body covered usually with a
harsh skin; (3) the gills attached by both margins, and the gill-openings
without opercula (g, fig. 462); (4) the optic nerves not decussating. The term
Figs. 462-472.
Selachians.—Fig. 462, Spinax Blainvillii (X be); 463, Spino of anterior dorsal fin, natural
size; 464, Cestracion Pbilippi (X bs)> 465, Tooth of Lamna clegans; 466, Tooth of Car-
charodon augustidens; 467, id. Notidanus primigenius; 468, id. Hybodus minor; 469, id.
Hyb. plicatilis; 470, Mouth of Cestracion, showing pavement-teeth of lower jaw; 471,
Tooth of Acrodus minimus; 472, id. Acrodus nobilis.
Selachian—proposed by Cuvier, and now used by Agassiz—is from the Greek
srAayof, cartilage, while Placoid is from 7r\a£, a jjlute. The rough skin is often
278
PALAEOZOIC TIME DEVONIAN AGE.
UL General Observations.
Geography.—In the first epoch of this period, that of the Cauda-
Galli grit, the beds were, as a body, more easterly in position over
called shagreen, and may sometimes be seen to be composed of minute rhombic
or angular pieces, each rising into a point at centre.
II. Ganoids.—Include the modern and ancient Gars (figs. 517-519), and the
Sturgeon, having (1) the skeleton cartilaginous or bony; (2) the gills as in
ordinary fishes; (3) the body covered with bo>iy plates or scales (figs. 474,
475), which are usually shining or enamel-like in surface; (4) the optic nerves
not decussating. The name Ganoid is from yams, shining, and alludes to the
scales.
III. Common or Osseous Pishes, or Teliosts.—The Perch, Salmon, and all
common fishes are here included. (1) The skeleton is bony, as the name Teliost—
from TtXcto;, complete, and oariov, hone—implies; (2) the gills have one margin
free; (3) the scales covering the body are membranous; (4) the optic nerves
decussate. The Cycloids of Agassiz have the scales unarmed with sharp points
(fig. 476); while the Ctenoids (from ktsis, a comb) have them armed (fig. 477):
but this subdivision is not a natural one.
1. Selachians.—The Selachians are divided into three groups, the Squa¬
loids, or Sharks, the Bays, and the Chimseroids. The Squaloids have an elon¬
gate body, with the gill-openings lateral; the Rays, a broad, flat body, with the
gill-openings in the ventral or under surface; the Chimaeroids, only one gill-
opening, besides other peculiarities.
The Squaloids include,—
(1.) The True Sharks, or Squalodonts, having sharp-edged teeth (figs. 465-467),
and the mouth on the under surface of the head (fig. 462).
(2.) The Hybodonts, having teeth nearly like the preceding, but with the edge
less acute : they are intermediate between the Squalodonts and the Cestraeionts
(figs. 468, 469).
(3.) The Cestraeionts, having a rough pavement of bony and usually enamelled
pieces in the mouth, and the mouth situated at the extremity of the head; fig.
464, Cestracion Philippi or "Port Jackson Shark," Australia; 470, side-view of
mouth, showing the pavement or grinding surface of lower jaw, with the pointed
teeth at the opening; 471, 472, different views of the pavement-pieces in the
Cestraciont genus Acrodus. In the genus Cochliodus the number of pavement-
pieces is very small, and they are proportionally large (figs. 546, 547), besides
having a spiral twist. These Cestraciont mouths were well fitted for masti¬
cating Ganoids and shell-fish.
The Chimseroids, including the living Chimserse and several extinct species,
have two to four osseous plates to either jaw in place of teeth.
Among the Rays, Myliobates and species of some related genera use their large
pectoral fins in swimming, instead of the tail, and the motion is much like that
of flying through the water,—so that they are sometimes called Sea-Eagles. The
mouth in this group is paved with four- or six-sided plates, evenly and neatly
joined.
CORNIFEROUS PERIOD.
279
New York than those of the preceding period. In the Schoharie
epoch they were still farther to the east than the Cauda-Galli grit;
at the same time they continue to be sandstones. But with the
next epoch there was a change. The continent from eastern New
In several genera of Selachians the dorsal fin is armed at its anterior margin
with a large spine. In the genus Spina* (fig. 462, reduced) there are such
spines, one to each dorsal fin; fig. 463 represents one of natural size for a fish
(Spina*) about 2f feet long.—Such spines exist also in the Cestracionts (fig. 464),
the Hybodonts, and Chimseroids. In these Squaloid groups the spine is usually
laterally compressed, and if denticulate it is so along the posterior margin. In
Trytjon and some other genera among the Rays, there is a similar spine, hut it
is flattened in a direction transverse to the body, and has both outer edges den¬
ticulate, when either is at all so. These spines in some ancient fishes were two
feet or more in length (see fig. 657). In a living Cestracion, 23 inches long, it
is II inches in length.
2. Ganoids—The following are the principal subdivisions of Ganoids
A. Placoganoids.—In these the body has a case or coat of mail, of large
enamelled plates, like that of a turtle. (1.) The Coccosteids have a fish-like
tail, and swim by means of it: Ex., Coccosteus. (2.) The Pterichthych, or "winged
fishes" (as the term signifies), have no caudal fin for swimming, but, instead, a
pair of powerful paddles (pectoral fins): Ex., Pterichthys (fig. 616). Thus there
are sculling and paddling Placoganoids, as well as Rays.
B. Scale-covered Ganoids, or Lepidoganoids. — They have the body
covered with scales set on either like tiles or like shingles, and on this differ¬
ence two subdivisions are based. Lepidoganoidx is from Atinj, a scale, and ganoid..
Figs. 473-481.
Ganoids (excepting 476, 477).—Fig. 473, Tail of Thrissops (X M); 474, Scales of Cheirolepis
Traillii (X12); 475, id. Palaconiscus lepidurus ( X 6); 475 a, under-view of same;
476, Scale of a Cycloid; 477, id. of a Ctenoid; 478, part of pavement-teeth of Gyrodun
umbilicus; 479, ,Tooth of Lepidosteus; 4S0, id. of a Cricodus; 481, Section of tooth of
Lepidosteus osseus.
(a.) Rhombifers, or Ordinary Ganoids.—The scales are rhomboidal or reef
angular, bony, usually thick, shining, and enamelled, and set on like tiles (fig'.
280
I'ALiEOZOIC TIME DEVONIAN AGE.
York westward became to a large extent covered with coral-grow¬
ing seas. The wide distribution of the rocks proves the vast area
of those coral seas. It also teaches that they were shallow seas;
for, as already remarked, corals grow and form limestones only
where they are within the reach of the waves. The Upper Ilel-
derberg period was eminently the coral-reef period in Palaeozoic
history.
Climate.—The question of the occurrence of rocks of this period
in the Arctic is not yet decided. It is probable that they exist
there, on North Somerset and elsewhere, judging from the fossil
corals and Brachiopods (Am. Jour. Sci. [2] xxvi. 120). Among the
former, besides the Favosites Gothlandica (Upper Silurian in Europe),
there are Heliolites porosa, and Cyathophyllum helianthoides, Devonian
species occurring in Europe and America.
This identity of species between the Arctic, and Europe and
America, just illustrated, favors an approximate identity of climate:
there is no sufficient evidence of a cold Arctic, or even of a wide
diversity of zones.
HAMILTON PERIOD (10).
Epochs.—1. Marcellus, or that of the Marcellus shale (10 a);
2. Hamilton, or that of the Hamilton beds (10 b) ; 3. Genesee, or
that of the Genesee shale (10 c).
474, 475). Fig. 475 a shows the under surface of 475, and illustrates the manner
in which the scales are locked together. Among them there arc (1) the Cepha-
luspids, having a broad buckler-head; Ex., Cephalaspis (fig. 517); and (2) the
Sanroids (figs. 473 and 519), having the form of ordinary fishes, and sharp,
though sometimes very small, teeth. Figs. 479, 480 are teeth (nat. size) of a
Lepidosteus, and a Cricodus. Other genera of this group are Dipterus, Cheiro-
lepis, Palxoniscus, etc. The Lepidoids of Agassiz are here included.
(b.) Imbricates.—Scales not rhombic, imbricate or set on like shingles, as in
Holoptijchias (fig. 518) and the modern Amia.
The Pycnodonts arc lthoinbifers, having smooth pavement-teeth. Fig. 478
represents part of the pavement-teeth in a species of Gyrodus.
C. Acipenseroids.—Include the modern Sturgeon, which has a cartilagi¬
nous skeleton, large rounded plates, and no teeth.
Labyrinthine structure of Ganoid teeth.—The teeth in the Sauroids, or at least
in many of them, have a labyrinthine structure within. This structure is illus¬
trated in one of its simplest forms in fig. 481, which is an enlarged section, by
Agassiz, of the tooth of a living Lepidosteus. It consists in a folding inward of
the enamel and dentine. In fig. 480 the strise of the tooth correspond to these
inward foldings.
HAMILTON PERIOD.
281
I. Rocks: kinds and distribution.
The rocks in the eastern United States are either shales or sand¬
stones, with some thin limestone beds. Shales especially abound
in the State of New York.
The Marccllus shale (10 a) is for the most part a soft, argillaceous
rock. The lower part is black with carbonaceous matter, and con¬
tains traces of coal or bitumen, so as sometimes to afford flame in
the fire. The Hamilton beds (10 b) in New York (so named from
Hamilton, Madison co., N.Y.) consist of shales and flags, with some
thin limestone beds. The excellent flagging-stone in common use
in New York and some adjoining States, often called North-River
flags, comes from a thin layer in the Hamilton. The Genesee shale
(10 c) is a blackish shaly rock overlying the Hamilton.
The Hamilton formation spreads across the State of New York,
having its northern limit along a line running eastward from Lake
Erie. The greatest thickness—about 1200 feet—is east of the centre
of the State. It extends southwest into Pennsylvania and Vir¬
ginia, and also westward, as a thin rock, mainly of limestone,
through parts of Michigan (at Mackinac), Illinois (at Rock Island,
etc.), Iowa (New Buffalo, etc.), Missouri, and elsewhere. Beds
probably of this period occur also in Maine, and near Gaspe.
[a.) Interior Continental basin.-—In the lower part of the Marccllus shale (the
rock of the first epoch) in New York, there are also layers of concretions of
impure limestone, and these abound most in fossils. But the fossils of the
shale are generally small.
The Hamilton beds consist of shales separated into two parts by a thin layer
of Encrinal limestone, and in many places overlaid by a thin limestone stratum
called the Tulhj limestone. In the
annexed section from the coast of
Lake Eric (as given by Hall), the
Hamilton beds, 10 h, include (1) blue
shale; (2) Encrinal limestone; (3)
Upper or Moscow shale : the Tully
limestone is wanting. Above lie
(10 c) the Genesee slate; and (11) a
part of the Portage group of the
next (Chemung) period.
The flagging-stone of the Hamilton is quarried near Kingston, Saugerties,
Coxsackie, and elsewhere on the Hudson in Ulster, Greene, and Albany cos.,
N.Y., and also near Cayuga Lake. The bed is but a few feet thick. It break?
into very even slabs of great size. It is almost without fossils, but is penetrated
in many parts by'thc filling of a slender worm-hole. The Genesee slate overlies
the Tully limestone when this is present. It is not recognized in the eastern
part of the State of New York.
Fig. 4S2.
Section of Hamilton beds, Lake Erie.
282
PAL2E0Z01C TIME—DEVONIAN AGE.
The Marcellus shale rarely exceeds in thickness 50 feet. The Hamilton strata
are 1000 feet thick in central New York, but not half this along Lake Erie.
They are also comparatively thin and more sandy on the east in the llcldcrberg
Mountains. They arc well exposed along the valleys of Seneca and Cayuga
Lakes. The Genesee shale is 150 feet thick near Seneca Lake; it thins west¬
ward, and is not over 25 feet on Lake Erie.
Still farther west it is represented by what is called the Black slate,—rather a
shale,—a very persistent stratum occurring in Tennessee, Kentucky, Indiana,
and elsewhere; it is a hundred feet thick at Louisville, Ky., and in Indiana.
In Missouri, the Hamilton formation consists of about 50 feet of shale, with
some beds of limestone.
b. Appalachian region.—In Pennsylvania, H. D. Rogers makes three divisions
of the Hamilton formation, a lower of black shales, which is 250 feet thick in
Huntingdon, a middle of variegated shales and flags, 600 feet thick at the same
place, and an upper black shale of 300 feet.
The thickness of the Hamilton formation east of central New York shows
that this region was at this time, as in the Oriskany period, on the northern
border or limits of the Southern Appalachian region.
At Gaspe, on the Gulf of St. Lawrence, the Devonian sandstones have a thick¬
ness of several thousand feet. They are regarded as belonging to the Lower
rather than Upper Devonian; but the precise ago has not been determined.
From the fossil plants it seems probable that the Hamilton period is represented
among them.
c. Eastern border.—At Perry, Maine, there are other Devonian strata con¬
nected with the Canada deposits, and they also may be of the Hamilton series.
The fossils thus far found have not served to fix their precise age. They
contain some species of fossil plants identical with those of Gaspe.
Ripple-mar Its.—The rocks of this formation, especially the Hamil¬
ton beds, are remarkable for the abundance of ripple-marks on the
layers. The flagging-stone is often covered with ripple-marks and
wave-lines. The joints intersecting the strata are often of great
extent and regularity. They have been referred to on page 100,
and a sketch is there given representing a scene on Cayuga Lake.
The rock at the place is the Moscow shale.
II. Life.
1. Plants.
The carbonaceous material of the black Marcellus shale is mostly
due to vegetation : but whether to sea-weeds or land-plants has not
been ascertained. In the Hamilton beds the evidence of verdure
over the land is no longer doubtful. The remains show that there
were trees, and of large size. Figs. 483 and 484 represent the outer
surface of two of the species, showing the scars left by the bases
of the fallen leaves. Fig. 483 is Lepidodendron primxvum, from near
HAMILTON PERIOD.
283
Huntingdon, Pa., and fig. 484, a Sigillaria, from Otsego co. and
other places in New York. The first is related, and probably both,
to the Lycopodia (Ground-Pine) of
modern damp woods. The largest
of living Lycopodia are three to four
feet in height. These earliest repre¬
sentatives of the type had trunks a
foot or more in diameter, and may-
have been more than a score of feet
in height. These plants are covered
with leaves much like Pines and
other Conifers; and the stem in
tig. 484 resembles that of a Spruce,
stripped of its leaves. In the Devo¬
nian of the vicinitv of Gaspe, of St.
John, New Brunswick, of Ontario co.
N. Y., and of other places, there is
true Coniferous fossil wood (Daw¬
son).
For remarks on the subdivision of Plants, see page 105. On the
frontispiece, representing a Carboniferous landscape, the stump in
the right corner is a Sigillaria; the highest tree in the same corner
is a Lepidodendron, and the smaller plants near it, having stems cov¬
ered with short leaves, are other Lycopodiaceous species; the high
tree in the left corner is also a Lepidodendron ; the tree towards the
middle of the view is a tree-fern, and the spreading leaves at its foot
are the fronds of low ferns.
The Coniferous plants are referred by Dawson to the genera Da doxy Ion and
Protaxites. In the Devonian rocks of Gaspe, St. John, and Perry in Maine, re¬
mains of many species of plants of the Sigillaria, Catamites, Lycopodinm, and
Fern tribes, etc., occur. Among them Lepidodendron Gaapiannm Dawson, Pxilo-
phyton princepn Daw., Cordaites any net if alia Daw., Cydopterin Jacl-sani, besides
others mentioned on page 290. A number of species are common to Perry, Maine,
and the New Brunswick beds. The rocks belong to the Upper Devonian, and are
either Chemung or Hamilton, or both. Nearly 100 species of American Devonian
land-plants are now known.
The relics of sea-weeds are common ; and one of the most abun¬
dant is related to the Fucoides Cuuda-galli (fig. 441). It is sometimes
a foot in diameter.
2. Animals.
The animal remains of the Marcellus are comparatively few,
and, excepting the Goniatites, generally small; their small num¬
ber corresponds with the fact that the rock is a fine shale. In
the Hamilton beds, which are coarser and often resemble a con¬
solidated mud-bed, fossils are much more numerous. With the
Fig. 483. Fig. 484.
Fig. 483, Lepidodendron primsevum;
484, Sigillaria.
284
PALAEOZOIC TIME DEVONIAN AGE.
Genesee slate there is a return to the fineness of the Marcellus,
and also in part to some of the same species of shells.
The preceding period had abounded in corals, and hence in lime¬
stones ; in the Hamilton, when the condition was unfavorable for
coral reefs over New York and south, there were still some fine
species of corals and Crinoids, but the predominant fossils were
Brachiopods and Conchifers,—species that live on muddy bottoms.
There were many broad-winged Spirifers, among which the &'p. mu-
cronatus (fig. 489) was very common. The limestone layers mark an
occasional change to clearer waters, when Crinoids and corals had
a chance to flourish.
With this period commence the earliest of Goniatites (fig. 498),—
a group of Cephalopods with Nautilus-like shells, but differing
from Nautilus in having the siphuncle dorsal, and the septa with
one or more flexures at the margin ; in case of one flexure or more,
there is always one on the dorsal margin, as in fig. 498 a. The
Goniatites became more and more complex in the flexures of the
septa during the following periods of the Palseozoic, and after¬
wards were replaced by the Ceratites and Ammonites, to which
they are closely related.
Characteristic Species.
1. Radiates.—Fig. 485, the Coral Heliophyllum Haiti, common in the
Hamilton at Moscow, York, and elsewhere, and found also in England. The
Enerinal limestone is made up of fragments of
crinoidal columns.
2. Mollusks.—(a.) Brachiopods.—Fig. 486,
Atrypn aspera, also European ; 487, A. reticularis,
regarded as the same species as that of the Cornife-
rous period, hut usually much larger and fuller,being
sometimes nearly two inches broad; 488, Tropidolep-
Ui8 carinatus, in New York, Illinois, Iowa, Europe;
489, Spinfer mncronatus, very common ; 490, Athy-
ris spiriferoides (Atrypa concentrica of Conrad),
—it has the spire internally of a Spirifer; 491,
Spirifer (Martinia) umhonatus, also European;
492, Chonetes setitjera, found in both the Marcellus
and Genesee shales; 493, Productus subalatus,
Itock Island, 111. A shell closely like the S. «/«-
boiia/us, but higher, oecurs in Iowa and Illinois, and is named Cyrtia vwLoiitti-i
by Hall. Spirifer granxdiferus is a large Hamilton species, having a granu¬
lated surface.
(5.) Coucliifers.—The species are often of large size, but none yet described
have a sinus in the pallial impression. Fig. 494, Ortkonota undulata Con.;
495, Avicula Flabella ; 496, Grammysia Harniltonensis,—also European, in the
Eifel; 497, Microdon bellistriatus Con. '
Fig. 485.
Heliophyllum Ilalli.
HAMILTON PERIOD.
285
(c.) Gasteropods.—A few species have been described. They are all without
a beaked aperture, like those of older time. The Bellerophon patulus is a broad
species of the genus, with a flaring aperture.
Figs. 486-493.
Srachiopods.—Fig. 486, A try pa aspera; 487, A. reticularis; 488, Tropiiloleptus carinatus;
489, Spirifer mucronatus; 490, Athyris spiriferoides; 491, Spirifer (Martinia) umbonatus;
492, Chonetes setigera; 493, I'roductus subalatus.
(d.) Cephalopods.—Fig. 498, Goniatites Marcellensis Van., a species sometimes
a foot in diameter, occurring in the Marcellus shale. Two small species, the
Fi s. 4 91-197.
Conchifers.—Fig. 494, Orthonota undulata (X %)'■, 495, Avicula Flabella (X 14); 496,
Grammysia Hamiltonensis; 497, Microdon bellistriatus.
G. unianrjularis and G. punctatus, are reported by Conrad from the Hamilton
beds. The genus Orlhoceras is represented by a few species of moderate
size.
286
PALAEOZOIC TIME DEVONIAN AGE.
3. Articulates, (a.) Crustaceans.—The Trilobites Pliacops Bvfo (fig.
499) and Dalmania calliteles (fig. 500, representing the posterior extremity) are
common in the Hamilton beds.
Figs. 498-500.
Oephalopod.—Fig. 498, Goniatites Marcellensis. Trilobites.—Fig. 499, PhacopsBufo; 500,
Caudal extremity of Dalmania calliteles.
(6.) Remains of Insects have been found in the Devonian beds of St. John, New
Brunswick, which are either of the Hamilton or Chemung period.
General Observations.
Geography.—The positions and nature of the Hamilton beds
indicate similar geographical conditions to those of many earlier pe¬
riods,—that a shallow sea covered New York and spread widely to
the west, and that many changes were experienced in the water-level;
the beds are to a great extent mud-beds, whence we learn that
they were deposited in quiet waters ; the fossils are marine, proving
marine waters. The beds in New York are thickest about its cen¬
tral parts, and vet spread to its eastern and western limits, ex¬
cepting the Upper, the Genesee shale, which is not known in the
eastern part; they are partly calcareous in the lower part of the
Marcellus beds, proving that the change from the condition of the
limestone-makingCorniferous period was gradual; limestone layers
occur higher up, at intervals, indicating changes of level, which
favored at times Encrinites and corals ; ripple-marked flags make
up some layers, proving by their evenness and extent, and the
regularity of the lamination, that the sea at the time of their forma¬
tion swept over extensive sand-flats, coming in over the present
region of the Hudson River or of New York Bay. The existence
of a barrier of sand along the ocean, such as is thrown up and at
intervals removed again by the waves, would account for the vary-
CIIEMUNG PERIOD.
287
ing conditions and also for changes in the living species by exter¬
mination.
Moreover, while these mud-accumulations were here in progress,
there were Hamilton limestones forming in some of the Western
States, indicating again the existence of the interior or Mississippi
sea,—a feature in a large part of both Silurian and Devonian
geography.
The Appalachian region is still an area of vastly the thickest,
deposits, and hence of the greatest change of level by subsidence;
and the great thickness of the formation (1000 feet) in central New
York makes it another example of the prolongation of the subsid¬
ing Appalachian region northward over southern New York. This
fact and the thinning of the beds towards the Hudson indicate
that the Green Mountain region was at least a few feet above the
sea, so that the great New York bay, alluded to in the observa¬
tions on the Oriskany beds, was still outlined on the east, although
communicating westward more or less perfectly with the interior
basin.
Life.—The land-plants of the Hamilton beds prove that the
rocks and soil of the emerging continent and its islands were not
then barren wastes, whatever their earlier condition. There were
forests of Conifers and Lepidodendra, besides smaller plants, but no
Palms or Angiosperms (p. 1G5)..
CHEMUNG PERIOD (11).
Epochs.—1. Portage, or that of the Portage group (11 a) ;
2. Chemung, or that of the Chemung group (lli).
I. Rocks: kinds and distribution.
Portage epoch.—The Portage group consists of shales and lami¬
nated or shaly sandstones. In western New York, on the Genesee
River, the lower beds are the Casliaqua shales; next, the Gardeau
shales and flagstones; then, above these, the thick Portage sand¬
stones. But going westward the shales increase in proportion,
and eastward the sandstones greatly predominate, the subdivisions
not continuing distinct; there are also changes in the fossils cor¬
responding with these variations.
The rocks have a thickness of 1000 feet on the Genesee River,
and 1400 near Lake Erie. (Hall.) They are well developed about
Cayuga Lake, but have not been recognized in the eastern half of
the State of New York.
1:88
PALAEOZOIC TIME DEVONIAN AGE.
Chemung epoch.—The Chemung group extends widely over the
southern tier of counties of New York, and consists of sandstones
and coarse shales in various alternations. The thickness has been
estimated at 1500 feet near the longitude of Cayuga Lake, and less
towards Lake Erie and beyond
Fig. 501.
Section of rocks of the Hamilton and Chemung Periods.
In this section, from one by Hall, taken in Yates co., N.Y., 10 a, 10 b, 10 c, are
rocks of the Hamilton period; a, the Marcellus shale; b, the Hamilton group;
c, the Genesee slate; and in the Hamilton group, 2 is the Encrinal limestone,
and 4 the Tully limestone; II a is the Portage group, 11 b the Chemung group.
Westward of New York the Portage and Chemung groups have been supposed
to be represented in Ohio by a sandstone called " Waverly sandstone," three to
four hundred feet in thickness. Many facts, however, point rather to the conclu¬
sion that the larger portion at least of this series really belongs to the Subcar-
boniferous, or is at any rate newer than the Chemung. Late investigations
also render it more than probable that beds referred to the Chemung in Missouri
and Iowa are really more recent.
To the south and southwest of New York, in Pennsylvania, and
beyond along the Appalachian region, the corresponding beds have
great thickness, amounting in some places to more than 3000 feet.
The rocks have the same sandstone character as in New York.
This remark applies to the beds in the northeast towards Gaspe;
for the Upper Devonian is represented in that part of the continent.
The beds at St. John's, New Brunswick, have been specially referred
to the Upper Devonian, but their precise parallelism with the New
York Devonian has not been determined.
The beds of both the Chemung and Portage groups in New York
and Ohio abound in ripple-marks, obliquely-laminated layers, mud-
marks, and cracks from sun-drying,—evidences of the existence of
extensive exposed mud-flats, of sandy or muddy areas swept by
the waves, and of tidal currents in contrary movement through the
shallow waters.
CHEMUNG PERIOD.
289
II. Life.
The Chemung period was as profuse in life as any that preceded
it, and yet was almost wholly different in its species from the
Hamilton.
1. Plants.
Besides the Cauda-Galli Sea-weed, there are remains of many land-
plants ; and thus we find that after the first appearance of an un¬
equivocal land-plant their relics are no longer rare fossils.
Figs. 502-504.
Fig. 502, Noeggeratliia Halliana; 503, Sigillaria Vanuxemi; 504, Atrypa hystryx.
In the Portage there are great numbers of Fucoids, or forms
regarded as fucoidal. The most common kind appear like short,
straight, simple stems, two or three inches long, scattered thickly
over the surface of the flagstones. In the Upper Portage there are
other cylindrical forms penetrating vertically the layers; but these
are probably the fillings of worm-holes, analogous to those of the
Potsdam sandstone (p. 185).
2. Animals.
The Portage beds, though abounding less in fossils than the Che¬
mung, contain various species of Crinoids, Brachiopods, Conchifers
(Aviculopectcns, Avicidcc, and others), Bellerophons, and Goniatites. A
large Crinoid—the Cyathocrinus t ornatissimus—occurs in great num¬
bers, broken to fragments, through a small area in the town of
Portland, on Lake Erie.
20
290
PALAEOZOIC TIME—DEVONIAN AGE.
The Chemung group in New York affords great numbers of
Aviculce, many Brachiopods, including broad-winged Spirifers, and
some Producti, a huge Goniatite (four or five inches in diameter), and
rarely a Trilobite.
Characteristic Species.
1. Plants.—Fig. 502.—Noeggerathia Halliana, Upper Chemung beds ; Sageva-
ria Chemungensis, from near Elmira, N.Y.; 503, Sigillaria Vanuxemi, from near
Owego, N. Y. Species of Calamites have also been found. At St. John's, New
Brunswick, occur the following species, first described, with one exception, by
Dawson: — the Dadoxylon Ouangondianum (a Conifer), Calamites Transitions
Goeppert, Asterophyllites pctrvula, Sphenophyllum antiquum, Lycopodites Matthewi,
Cordaites Robbii, a Sphenopteris, Cyclopteris Jacksoni, and others. The Cyclop-
teris occurs also at Perry, Maine. (See further, p. 283.)
Figs. 505-507.
Fig. 505, Aviculopeeten duplicatus; 506, Pteronites? Chemungensis; 507, Orthoceras
Acicula.
2. Animals.—Fig. 504, Atrypa Hystrix ; Fig. 505, Aviculopeeten duplicatus ;
Fig. 506, Pteronites ? Chemungensis; Fig. 507, Orthoceras Acicula.
III. General Observations.
Geography.—The character of the beds—the shales that were
made from mud-beds and the shaly sandstones from sand-deposi¬
tions—which spread over western and southern New York and
southwest along the Appalachian region, which become more shaly
to the western limit of the State and more sandy in the opposite
direction, tells nearly the same story with regard to the geography
of the continent as in the Hamilton period. The rocks were largely
shallow-water or sand-flat formations, as shown by the ripple-marks,
shrinkage-cracks, and oblique lamination ; and they therefore indi¬
cate by their great thickness a subsidence during their progress to
a corresponding extent, and, further, that this subsidence or change
of level affected most the Appalachian region. The shallow sea
probably extended westward, forming sandy deposits over Ohio,
though of much less thickness than in New York.
CATSKILL PERIOD.
291
Life.—In its plants the Chemung period indicates the approach
of the Carboniferous age,—the genera Lepidodendron, Sagenaria,
Sphenopteris, Catamites, being characteristic of that time. Its animal
species bear marks of new progress, in the great Goniatiles, with more
complex septa, and the greater abundance of large-winged Spirifers,
as well as the occurrence of species having spinous shells.
CATSKILL PERIOD (12).
I. Rocks : kinds and distribution.
The rocks of the Catskill period are shales and sandstones of
various colors, in which red predominates. The sandstones are far
more extensive than the shales, and pass into conglomerates or
coarse grit-rock, and also into a rough mass looking as if made of
Pig. 507 A.
Noeggeratbia obtusa.
cemented fragments of hard slate. The upper part is in general a
conglomerate. There are ripple-marks, oblique lamination, and
other evidences of sea-shore action, in many of the strata. Some of
the layers are partially calcareous.
292
PALAEOZOIC TIME DEVONIAN AGE.
The formation, instead of thickening to the westward in New
York, like those preceding it in time, thins out in that direction,
and thickens towards the Hudson, being two or three thousand
feet in the Catskills. It stretches south along the Appalachian
region, beneath the Coal formation of Pennsylvania and Virginia,
where it is 5000 or 6000 feet thick. It is eminently an Appalachian
formation.
II. Life.
The rocks afford but few relics of animal life, and these differ
completely from those of the earlier periods. There is thus, as
appears, a new beginning in the life of the continent. It is, how¬
ever, yet uncertain what were the condition and life of the interior
region, as no strata have been there recognized as certainly of
this era.
1. Plants.—The land-plants, relics of which are occasionally met with, were
of the same Carboniferous character as in the Chemung period. Fig. 507 A
Fig. 508.
Modiola angusta.
represents a portion of a large frond of the Noeggerathia obtusa, from Montrose,
Pa.,—a characteristic fern of the period. The frond was over a foot broad.
Figs. 509-511.
Fig. 509, Holoptychius Americanus; 510, Tooth, id.; 510 a, section of same tooth;
511, Holoptychius Taylori.
2. Animals.—Among animals, no Corals, Crinoids.Brachiopods, orTrilobites, are
yet known. There are some Conchifers, such as (fig. 508) the Modiola angusta
CATSKILL PERIOD.
2S3
(Cypricardin anrjuita Con.), and a few other species, and a Euomphalus; these, with
fragments of fishes, make up about all that is yet known respecting the animal
fossils of the beds. Among the fishes there are (fig. 509) Holoptyehius Americanus
(510 being a tooth of the-same, and 510 o, a section of the latter); 511, Holo¬
ptychius Tuylori. The latter species was of large size, a portion of one of the
fins found in New York indicating a length of more than a foot for the entire fin.
III. General Observations.
Geography.—The location of the Catskill beds in eastern New
York instead of central or western (like the Hamilton and Che¬
mung), and their thickness there, show that a great geographical
change preceded the opening of the period. The Appalachian
subsidence, instead of extending north over central New York,
involved the Hudson River valley, far to the eastward ; and the
amount of subsidence both here and in Pennsylvania and Vir¬
ginia was much greater than in the preceding periods. The
change, moreover, was attended with a complete destruction of all
pre-existing life,—more complete than occurred in any other part
of the Devonian age. Whether the Interior Continental basin was
an area of dry land or of water, is not clearly apparent. The most
probable supposition is that the great sinking of the border region
of the continent was attended with a rising of western New York
and the interior, and that the extermination of life was thus pro¬
duced. In this event the Devonian age ended. After this, New
York State, excepting a border on the south, lay to the north of
the region undergoing progress through new formations ; for the
greater part of it was probably part of the dry land of the
growing continent. The rocks of the Coal age, with the small
exception alluded to, do not spread over it. Some geologists
would make the Devonian age close with the Chemung period ;
but the fossil fishes of the Catskill beds, according to Dr. New¬
berry, appear to represent closely those of the British Old Red Sand¬
stone or Devonian, and no similar species have been found in the
Burlington or other Subcarboniferous limestones of the West.
If the view presented be correct, there is a bold transition from
the closing period of the Devonian age to the opening of the
Carboniferous. The former was a period in which the great Appa¬
lachian subsidence (as in other parts of the Devonian) reached
north into the State of New York, while in the latter it hardly
passed the limits of Pennsylvania. The former was characterized
by dry land over the great Interior Continental basin ; the latter,
by a wide-spread, and clear though not deep, sea, growing Crinoids
and forming limestones ; for the Subcarboniferous limestone forma-
294
PALAEOZOIC TIME DEVONIAN AGE.
tions are among the most extensive in the geological series, and
crinoidal remains are in great profusion.
FOREIGN DEVONIAN.
I. Rocks : kinds and subdivisions.
The Devonian rocks occur as surface-strata in most of the coun¬
tries of Europe, and in parts of all the other continents.
In the British Isles, they are exposed to view in southern Wales
and the adjoining county of Herefordshire; in the peninsula of
Devonshire and Cornwall ; along the southern flank of the Gram¬
pians, and on the northwestern side of Lammermuir from Dunbar
to the coast of Ayrshire, in the valley of the Tweed, and elsewhere,
in Scotland; and also in Ireland and the Isle of Man.
On the map, fig. C05, the Devonian areas are distinguished by
vertical lines.
The strata in England and Scotland have long gone by the name of
the Old Red Sandstone,—red sandstone being the prevailing rock in
Wales and Herefordshire as well as Scotland. With the sandstone,
there are beds of marl or argillaceous shale, and some limestone.
The beds of Wales are argillaceous shales or marls, of red and other colors,
with some whitish sandstone and impure limestone, overlaid by red sandstone
which passes above into a conglomerate; and the whole thickness is estimated
by Murehison at 8000 or 10,000 feet. The limestone is concretionary, and is
called Comstone.
Iu Scotland there are, according to Hugh Miller, the following subdivisions:—
r 3. Yellow sandstone ; containing Iloloptychiim, etc.
3. Upper, -j 2. Concretionary limestone.
ll. Red sandstone and conglomerate.
2. Middle—Gray sandstones and shales ; containing Cephalanpiv, etc.
3. Red and variegated sandstone.
1 Lower i Bituminous schists; containing Diptema, Pterichthys, Coucos-
I tens, etc.
11. Conglomerate and red sandstone.
In Devonshire and Cornwall the strata are of very different character. They
are stated by Sedgwick as follow:—
| 2. Pethcrwin slate and Clymenia limestone,
t1. Marwood sandstones.
f Roofing-slates and quartz, with variegated sandstones
1 above, in north Devon.
r 3. Red sandstone and flagstone.
I 2. Calcareous slates.
11. Great Devon limestone.
1. Liskeard or Ashburton group.
4. Petherwin group.
3. Dartmouth group.
2. Plymouth group.
FOREIGN DEVONIAN.
295
In the Eifel (Rhenish provinces) there are, below, slates and sandstones ; next,
the great Eifel limestone, the equivalent, apparently, of the Upper Ilelderberg;
and above this, slates with an intermediate limestone,—the whole termed tho
Cypridina slates.
In Russia, the Devonian formation is exposed over a groat extent of country.
The rocks arc mostly marls and sandstones with laminated limestones. Accord ¬
ing to Kutorga, the prevailing order is marls below, then sandstones, then argil¬
laceous limestone.
There is thus a great diversity in mineral character, and no con¬
formity in the subdivisions of the Devonian with those in America.
As already explained, these subdivisions are in general due to
causes that have acted too locally to be often alike and synchronous
in very distant regions.
II. Life.
Plants.—Europe and Britain have afforded, in addition to sea¬
weeds, remains of plants related in genera to those of the Coal
period; so that from an early period of the Devonian the land of
other continents besides America had its Ferns and Conifers. The.
earliest fossil Conifer in Britain was found by Hugh Miller in his
lower division of the Old Red Sandstone of Scotland.
In Goeppert's recent memoir on the plants of the Silurian, Devonian, and
Lower Carboniferous rocks, he gives 20 Silurian species, all Algie ; in the Lower
Devonian, 5 Ahjte and 1 Sigillaria ; in the Middle Devonian, 1 Sarjenaria ; in the
Upper Devonian, 57 species, all but 7 land-plants.
Animals.—The range of animal life was similar to that of Ame¬
rica. A few species of Europe and America were identical; but
the great majority were distinct, showing that the continents did
not derive their life from one another. But as regards genera the
identity was very nearly complete. The continents were marching
on with nearly equal step in the progress of life.
Corals were abundant in Europe, especially Favosites and the
Cyathophylloid species, and coral-reefs were forming in the Eifel
and some other parts. Mollusks were most abundantly represented
by Brachiopods, and Crustaceans by Trilobites and the little Ostracoids.
Among Brachiopods, Spirifers were very common, and the genus
Productus made its first appearance, along with others of less pro¬
minence. Goniatites also (a genus of Cephalopods) was a new type,
and became well represented before the close of the age.
The sub-kingdom of Vertebrates included numerous fishes,—
some that were several feet long: they were all either Selachians or
Ganoids. A few are represented, of reduced size, in figs. 516-519.
With so powerful species in the water, it is not a matter of surprise
296
PALAEOZOIC TIME DEVONIAN AGE.
that the clumsy Orthocerata of the Silurian age were succeeded by
fewer and smaller species.
Just before the Devonian age closed, there were Reptiles in the
world. This is a second step in the unfolding of the Vertebrate
type. The skeleton of one small species, called Telerpcton, is repre¬
sented in fig. 520. Moreover, besides these remains, tracks of
Amphibians have been observed, proving that air-breathing animals
frequented the marshes.
Characteristic Species.
1. Radiates.—Among Kadiates there were species of Pentremites, the earliest
in Europe of the group of Blastoid Crinoids.
2. Mollusks.—Brachiopods included species of Or this, Strophomena, Atrypa,
Rhynchonella, Spirifer, Productus, Chonetes, etc.; besides Calceola and Stringo-
cephalus, which are confined to the Devonian age. Fig. 231 is the Calceola san-
dalina (so called from the sandal-like shape of the shell). This genus characterizes
the Calceola schist which underlies the great Devonian limestone of the Eifel.
Conchifers were numerous of the genera Avicula, Aviculopecten, Pte.rinea, Nu-
cula, Conocardium; also of Area, Grammysia, Mctjalodon, etc. There were
Gasteropods (all without beaks) of the old genera Murchisonia, Euomphalus,
Pleurotomaria, Loxonema, Bellerophom etc. There were others also of the new
genus Porcellia, which is near Bellerophon, and somewhat resembles an Am¬
monite in form, hut has a deep dorsal slit in the aperture of the shell.
Figs. 512, 513.
Cephalopods.—Fig. 512, Goniatites retrorsus; 513, Clymenia Sedgwickii; 513 a, dorsal view
of septa.
Cephalopods include a few species of the Orthoceras family,—also Nautili, and
several species of the new genus Goniatites, of the Ammonite family, and of
FOREIGN DEVONIAN.
297
another, called Clymenia. Fig. 512, Goniatit.es retrorsus; fig. 513, Clymenia
Sedtjwickii. The shell in Clymenia has the form in the Ammonites, but, unlike
the Goniatites and Ammonites, the siphuncle is ventral instead of dorsal, and
the septa have no distinct dorsal lobe on the medial line, as shown in fig. 513 a.
3. Articulates.—There are a number of species of Trilobitcs, though less
than in the Silurian : the genus Phacops or Dalmania is most common. Homalo-
notus has European species, and one, H. arm a tux, has spines on the head and two
rows along the back. This spinous feature reaches its maximum in the Devonian
Arges armatus (fig. 514).
Figs. 514, 515.
Crustaceans.—Fig. 514, Argus armatus; 515, Slate containing Cypridina serrato-striata,
natural size ; 515 a, same, enlarged.
Minute Ostracoids, referred to the genus Cypridina, abound in the Cypridina
slate, giving this name to the beds. Fig. 515 represents a portion of the slate or
Fig. 516.
Pterichthys Milleri.
shale with the shells of the Cypridina serrato-striata on its surface, natural size,
and 515 a is one of the shells, enlarged.
298
PALAEOZOIC TIME DEVONIAN AGE.
4. Vertebrates.—In the Devonian rocks of Great Britain and Europe, a
large number of species of fishes have been found; and when we consider how
little likely fishes are to become buried and fossilized, we begin to appreciate
their vast abundance in the Age of Fishes.
Among Ganoids, fig. 510 represents the Placoderm Pterichthys MiUeri (as
restored by Pander), reduced to half the natural size. The Coccosteus resembles
it in its plates, but has a longer tail, fitted for sculling by means of a fin along the
upper and under sides. Fig. 517, the Rhombifer Ganoid Cephalaspis RyeUii ;
figs. 517 a, 517 b, scales of the same; fig. 518, the Imbricate Ganoid Holopty-
chins; fig. 518 a, scale, id.; fig. 519, another Rhombifer, Dipterus macrolepi-
dotus.
Figs. 517-519.
Ganoids.—Fig. 517, Cephalaspis Lyellii; 517 a, b, Scales, id.; 518, Holoptychius; 518 a,
Scale, id.; 519, Dipterus niacrolepidotus; 519 a, Scale, id.
Asterolepis Asmusi Agassiz, whose remains occur both in Russia and Scot¬
land, must have been 20 to 30 feet long.
Reptiles.—Fig. 520, Telerpeton Elyinense Mantell, a species found on the south
side of the Moray Firth, in a whitish sandstone rock which is regarded by most
GENERAL OBSERVATIONS.
209
geologists as Devonian, though suspected to be Triassic. The animal appears
to have been more Lacertian than Batrachian; and this superiority to other
Fig. 520.
Telerpeton Klginen*«.
species of the next period is partly the occasion of the doubt as to its being true
Devonian. In the same quarry there have been observed thirty-four consecutive
footprints of a four-footed animal which was probably amphibian. The tracks
of the fore-feet are one inch broad, and those of the hind-feet three-fourths of
an inch, while the stride was four inches.
GENERAL OBSERVATIONS ON THE DEVONIAN AGE.
American Geography.—1. General features.—The facts gathered
from the Silurian strata lead us to conceive of the age—far the
longest of all the ages, excepting the Azoic—as one of small, barren
lands in the midst of great waters. We may suspect the existence
of land-plants; yet the suspicion is not sustained by observation.
But before the Devonian age had half passed, the land had become
covered with vegetation, preparatory for a freer and nobler life
than that of the waters. Still, the dry land of the continents had
increased but little in extent. The Azoic area, which had been
enlarged on the north by successive additions from emergence
during the Silurian, had expanded farther in the same direction,
until, at the close of the Devonian, the State of New York formed
a part of the land that bore the new vegetation. For, as seen on
the map, p. 170, the rocks which succeed one another reach less
and less far northward, proving that there was this progress south¬
ward with each period.
The general map on page 133 shows the area over which the
Silurian and Devonian formations are now uncovered in other parts
300
PALAEOZOIC TIME DEVONIAN AGE.
of the United States. But we cannot conclude that no later rocks
ever existed over these areas ; for extensive strata may have been
washed away in the course of subsequent changes. Yet there had
been progress in the dry land from the north, southward, along the
region of Ohio and Wisconsin, as in the State of Yew York, and
also from the Azoic axis of the far north, westward and east¬
ward : so that a general expansion of the old Azoic had taken place,
by additions to all of its borders. South of New York, and over a
large part of the continent, the surface was still liable to alternate
sinking and rising, and was, therefore, open to new formations.
North America was in the main a continental sea, with the extent
of land that was permanently dry very limited as compared with
the present finished continent.
In place of the Rocky Mountains and Appalachians, there were
only islands, reefs, and shallow waters, to mark their future site:
for Carboniferous strata and others of later age cover the slopes of
the Western mountains even over their summit-plains, and a lime¬
stone of the Carboniferous age has been observed in one place at a
height of 13.000 feet above the sea. The fossils of these rocks are
the remains of animals that lived in the continental seas of that
region in the next age after the Devonian. The Appalachians also
contain in their structure rocks of the Devonian and Carboniferous
eras. The Green Mountains have been already spoken of as in
part dry land ; but, as rocks of the Devonian and Carboniferous
seas constitute portions of New England, they could not have had
their present elevation, and were probably low.
It follows, from the limited area of the land and the absence of
high mountains, that there were no large rivers at the time. With
the close of the Devonian the Hudson River may have existed
with nearly its present limits, and in Canada the Ottawa and other
streams drained the northern Azoic. Even the St. Lawrence above
Montreal may have been a fresh-water stream.
2. Mocks of mar inc. and not of fresh-ivater origin.—None of the strata
bear evident marks of fresh-water origin. The shale deposits and
mud-rocks, which have been described, are such as might have
been formed by fresh waters ; but they all contain fossils, few or
many, which are of the same genera and often the same species
with those of beds obviously marine. Proofs of fresh-water deposi¬
tions, therefore, still fail us. Their absence may be accounted for on
the grounds—(1) that there were no great rivers ; (2) that whatever
material was borne to the sea was worked up by the waves and
filled with marine life; and (3) that depositions over the land, ex¬
cepting perhaps in those parts of the continent that were perma-
GENERAL OBSERVATIONS.
301
nently dry, would have been arranged anew by the waves in times
of submergence.
3. Geographical changes.—The history of the periods of the Devo¬
nian has been shown to be, like that of the Silurian periods, a history
of successive oscillations in the continental level,—the position of
the accumulating deposits varying more to the east or to the west
with the varying location of the subsiding or emerging areas.
Throughout the whole, the Appalachian region continued to be
well defined. Its deposits consisted mainly of shales and sand¬
stones, and they have a total thickness of not less than 15,000
' feet; while in the West the rocks are for the most part limestones,
with a thickness of less than 500 feet.
It appears, moreover, that in the Devonian as well as Silurian
age, the interior region was covered with but thin beds of any
kind,—thin sandstones when sandstones were formed, and thin
limestones compared with the cotemporaneous shales and sand¬
stone strata farther east; and hence the oscillations of level there
indicated are small as compared with those of the Appalachian
region. Moreover, from the prevalence of limestone strata in the
West we learn that the great mediterranean sea of the Silurian age
was continued far into the Devonian, opening south into the
Atlantic and Gulf of Mexico, and reaching north probably to the
Arctic. Through some parts of the West, the Niagara and Upper
Ilelderberg limestones-—the formations of that interior sea—follow
each other with but little interruption.
European Geography.—The European continent in the Devonian
age could not have had the simplicity of features and movement
that characterized the American. It is obvious from the great
diversity of the Devonian rocks—-sandstones at one end of Britain
and limestones at the other, limestones in the Eifel on the Rhine
and almost none in Bohemia—that the continent had not its one
uniform interior sea like North America, but was an archipelago,
diversified in its movements and progress.
There may have been proportionally more elevated heights over
the area; but it is still true that there was little of it dry ; that the
loftier mountains had not been made,—the Alps and Pyrenees being
hardly yet in embryo : and that, with small lands and small moun¬
tains, rivers must have been small. No fresh-water deposits have
yet been distinguished ; the salt ocean was nearly universal. Within
it, animals were living, and the continent was forming at shallow
depths.
Life.—The introduction of land-plants and that of f shes are the
two great steps of progress that especially mark the Devonian age.
302
PALAEOZOIC TIME DEVONIAN AGE.
The land-plants belong to two prominent groups,—Conifers and
Acrogens (p. 1GG). The former are the lowest of flowering plants,
the latter the highest of the flowerless plants, or Cryptogams.
Mosses, an inferior group of Cryptogams, are unrepresented. Thus
the new creations commenced with neither the highest nor the
lowest of plants, hut at an intermediate point in the series, where
the lower and higher groups come together. There was neither
moss nor grass ; and no showy flowers existed to contrast with the
verdure. The Conifers have inconspicuous flowers, and of all flower¬
ing plants approximate most nearly in fructification to the Acrogens.
Moreover, between the Acrogens and the Conifers of the era there
was an intermediate group (although most closely related to the
latter), which included the Sigillarise: so that there was a remark¬
able unity in the early botany of the world. The Acrogens repre¬
sented belong to the Lycopodium, Equisetum, and Fern tribes.
The Fishes of the age are also of two groups,—the Selachians, or
Sharks, and the Ganoids. The earliest species, therefore, instead of
being the lowest of fishes, belong to the highest of the three grand
divisions: moreover, instead of being small, some of them were
twenty or thirty feet long. The Selachians are highest among
fishes even in modern seas.
These early fishes—especially the Ganoids—have strong Reptilian
characteristics, as Agassiz long since observed, and they were thus
comprehensive types, foreshadowing the class of Reptiles afterwards
created. Hence, while plants began at the middle of the scale,
Fishes commenced at the top,—not, indeed, with the very highest
tribes of the groups introduced, for these belong to later time; but
the groups themselves rank highest in the class of Fishes, as stated.
In fact, the commencement was at a point above the true level of
Fishes, verging towards the higher grade of Reptiles; and it was not
till long afterwards that the fish-type appeared in its purity.
Among Ganoids, the species of Pterichthys (fig. 51G) have many of
the characters of a turtle,—its paddles and its covering of plat es ; and
those of Coccostcus present features of some sculling reptiles. Many
of the other Ganoids are Sauroid, in having the teeth closely like
those of the early Reptiles, and a joint made of concave and convex
surfaces at the junction of the head and neck, hence admitting of
some motion,—a characteristic belonging to none of the common
osseous fishes (Teliosts). Another Reptilian characteristic is the
lung-like structure of the air-bladder, the organ which answers to the
lung in air-breathing Vertebrates. Moreover, the old Ganoids bear
two striking marks of antiquity: (1) they have cartilaginous skele¬
tons, and (2) vertebrated tails. Besides, they are at the present
GENERAL OBSERVATIONS.
808
time nearly an extinct tribe. With a rare exception, the vertebrate
character of the tail does not recur after the Palaeozoic.
The further history of the type of Fishes is a subject of special
interest, as will appear in the sequel.
Besides land-plants and fishes, reptiles are supposed to date from
the last epoch of the Devonian,—though the evidence is not beyond
suspicion, as stated on p. 299. If correct, the beds may still be
synchronous with those called Lower Carboniferous in Pennsyl¬
vania, in which similar tracks have been observed ; and in this
case the discrepancy between the facts thus far ascertained on the
two continents is slight. Remarks on the Reptilian remains are
therefore deferred to a following page, under the Carboniferous.
The progress of life during the Devonian is further seen in—
(a.) The introduction of many new genera under old tribes ; for
examjfie, Productus among Brachiopods, which began in America
in the Corniferous period, and had its maximum display, and also
its extinction, in the Carboniferous age; Goniatites among Cephalo-
pods, which had its earliest American species in the Hamilton
period, and became extinct at the same time with Productus,—
a genus of interest, as it is the first of a family (that of Ammon¬
ites) which had a wonderful extension under other genera in the
Reptilian age, and became extinct to its very last species at the
close of that age ; Nuclcocrinus (fig. 452), the earliest (after a single
Lower Silurian genus) of the Pcntranites, another of the eminently
Carboniferous types; the ellipsoidal form of Hucleocrinus is changed
to the pentagonal of Pentremites (fig. 581) with the first of the
Subcarboniferous species, or even before, in the Upper Devonian.
{b.) The complete or approximate extinction of tribes: as that
of the Cystids, which ended with the Oriskany period in America
and the epoch of the Eifel limestone in Europe ; that of Favistella,
Heliolites, and other genera of Corals and Crinoids ;' that of Airy-pa,
Calceola, Stringocephalus, and other genera of Brachiopods; that of
the Chain-coral, or Ilalysites, which does not appear above the Upper
Silurian in America, but is found in the Eifel limestone in Europe:
that of Trilobitcs, which, after there had been, under a succession of
genera, over GOO species, came nearly to its end in the Devonian,
the old genera being all extinct, and only three new ones appearing
in the Carboniferous, to close off this prominent Palaeozoic type ;
the Orthoceras family, species of which are comparatively rare fossils
after the Devonian age.
(c.) In the historical changes in tribes or genera : for example,
the Spirifers, which began in narrow species in the Upper Silurian,
become broad-winged and very numerous in the Devonian, and
304
PALiEOZOIC TIME—DEVONIAN AGE.
continue thus into the Carboniferous; the genus Productus, whose
earliest species are very small and few, are afterwards of large size
and numerous. These changes do not consist in the gradual varia¬
tion of the earlier species ; for species are essentially constant in
their characteristics. They become apparent solely in the succes¬
sion of species,—the later species created differing in the particulars
mentioned from those which preceded them.
Each of these points admits of extensive illustration; but the
above is sufficient to give an idea of the kind of progress life was
undergoing. Each period had its new creations and its extinctions,
and often, also, there were many successive creations and extinctions
in a single period. Families and tribes were in constant change;
and through all these changes the system of life was in course of
development.
Threads running through past time to the present era increased
very slowly in number; for to the genus Lingula, which, if correctly
determined, reaches to the farthest distinguishable limit in the his¬
tory of animal life, with Nautilus, Phynchonclla, Plcurotomaria, Crania,
and Piscina, of the Silurian, only Nucula, Tercbratula, and perhaps
Area, are added in the course of the Devonian age. These genera
are all Molluscan. Every other (exclusive of some comprising the
inferior organisms called Rhizopods, see p. 1G3) becomes extinct
before the Age of Man. The early life was thus cast off, as the
earth became adapted to new forms in the expanding system.
DISTURBANCES CLOSING THE DEVONIAN AGE.
In eastern Canada, Nova Scotia, and Maine, the Devonian and
Silurian strata are uplifted at various angles beneath unconform¬
able beds of the Carboniferous (Dawson, Logan, C. Hitchcock).
These uplifts preceded the Carboniferous age (or at least the Car¬
boniferous period) ; but the precise epoch of their production—
that is, whether before the close of the Devonian age, or not, or
whether partly in the Silurian—is yet to be ascertained. Those
in Maine, according to Hitchcock, probably took place at the
close of the Devonian; and the same may be true of the others
alluded to.
In Iowa, Wisconsin, and Illinois, there are also similar uplifts;
but the Lower Carboniferous strata are involved in the disturbance,
and these, with the subjacent beds, lie unconformably beneath the
Coal formation. Here, therefore, the uplifts must have taken place
partly at least (perhaps wholly) after the period of the Lower Car¬
boniferous.
PALAEOZOIC TIME—CARBONIFEROUS AGE.
305
In England and Bohemia, also, examples of disturbances between
the Devonian and Carboniferous have been observed.
But all these cases are small exceptions to the general fact that
the Lower Carboniferous and the underlying rocks are conformable
almost the whole world over. The epoch of transition was not an
epoch of general disturbance. There were extensive oscillations
of level, but in general they involved no violent upturnings. The
Carboniferous age opens with a period of marine formations, and
the beds accumulated, in most regions where they occur, as a regu¬
larly-continued series.
CARBONIFEROUS AGE.
This age is divided into three periods:—
I. The Subcarboniferous Period (13).
II. The Carboniferous Period (14).
III. The Permian Period (15).
The Carboniferous age, both in America and Europe, commenced
with a preparatory marine period,—the Subcarboniferous ; had
its consummation in a long era of extensive continents, covered
with forests and marsh-vegetation, and subject at long intervals to
inundations of fresh or marine waters,—the Carboniferous ; and
declined through a succeeding period,—the Permian, in which the
marsh-vegetation became less extensive, and the sea again pre¬
vailed over portions of the Carboniferous continents.
American Geographical Distribution.
The rocks of the Carboniferous age lie at the surface over large
areas of North America. (See map, p. 133, in which the black
areas and those cross-lined or dotted on a black ground are of
this age.)
A. In the United States:
1. Over parts of Rhode Island and Massachusetts, between New¬
port and Worcester.
2. Along the Appalachian region from New York into Alabama,
and spreading west over half of Ohio, and part of Kentucky and
Tennessee, and a little of Mississippi.
3. Over central Michigan.
21
306 PALAEOZOIC TIME CARBONIFEROUS AGE.
4. Over much of Illinois, and spreading eastward over part of
Indiana, southward over part of Kentucky, westward over part of
Iowa, Minnesota, Missouri, Kansas, Arkansas, and large portions
of the Rocky Mountain slopes.
5. In Texas over parts of the more northern counties, being an
extension of the Arkansas coal region.
6. About the summits of the Rocky Mountains, near several of
tlie passes; around the Great Salt Basin in Utah; in the Colorado
basin, New Mexico, and over some other parts of the Pacific slope
of the Rocky Mountains.
B. In the British Provinces:
1. Over much of New Brunswick and part of Nova Scotia.
2. In the Arctic, over Melville and other islands between Grinnell
Land and Banks Land.
The Coal measures cover a large part of most of the regions here
pointed out, the rest being occupied by the Subcarboniferous and
Permian, or by limestones and other barren beds of the Carboni¬
ferous period.
Excepting the areas west of the Rocky Mountains, the whole
pertain to three great regions or basins:—
I. The Interior Continental region, including the Appalachian area on
the east, and stretching west to western Kansas, and perhaps still
farther, to or beyond the summit of the Rocky Mountains; for Car¬
boniferous rocks probably underlie the later beds now at the surface.
It is divided into two parts by the Lower Silurian uplift about Cin¬
cinnati and the region southwest.
II. The Atlantic border region, including the New Brunswick and
Nova Scotia region, and that of Rhode Island,—also divided into
two parts, a northern and southern.
III. The Arctic region.
1. SUBCARBONIFEROUS PERIOD (13).
I. Rocks: kinds and subdivisions.
In the Interior Continental region the Subcarboniferous rocks are
mainly limestones. They are largely displayed in Illinois, Ken¬
tucky, Iowa, and Missouri, and in the last they have a thickness
of 1200 feet. They also occur in Arkansas and Texas. In Ten¬
nessee there are two groups: the lower, siliceous beds ; the upper.
limestone. In Michigan there are about 70 feet of limestone,
resting upon 480 feet of shales and sandstones. The great lime¬
stone of the Carboniferous age over parts of the slopes and sum-
SUBCARBONIFEROUS PERIOD.
307
mits of the Rocky Mountains is regarded as belonging mainly to
the Carboniferous period, and not to the Subcarboniferous.
In the Appalachian region of Pennsylvania, the rocks are sand¬
stones and shales, and are divided into two groups. The Lower
consists mainly of sandstones, and is thickest and most varied in
composition in the vicinity of the southeastern anthracite coal
region, in which, at Pottsville, the thickness is 1800 to 2000 feet. It
diminishes rapidly in thickness to the west. The Upper is composed
mostly of shales. It attains its maximum thickness in the same
region as the Lower, being 3000 feet thick on the Lehigh, at Mauch
Chunk. It thins out to the northward, and becomes somewhat
calcareous to the southwest. (Rogers.) In Virginia the shales
become still more calcareous, and a great formation of Subcarboni¬
ferous limestone commences which extends into Alabama.
Going westward from Pennsylvania into Ohio, the fragmental
deposits diminish in thickness, and become reduced to a com¬
paratively thin group of arenaceous beds.
There are thin workable seams of coal in some of these Subcar¬
boniferous beds of Pennsylvania and Virginia, and also valuable
beds of clay iron-ore.
(a.)Interior Continental basin.—The Subcarboniferous limestone of the Mis¬
sissippi valley—especially in Illinois and Iowa—is divided, according to Hall,
into five distinct groups, each having its characteristic fossils:—
1. The Burlington limestone (500 feet thick in Missouri), overlaid in Iowa by
cherty beds (60 to 100 feet).
2. The Keokuk limestone (40 or 50 feet at Keokuk).
3. The Warsaw limestone (50 to 100 feet).
4. The St. Louis limestone (250 feet thick), overlaid by ferruginous sandstone
(200 feet).
5. The Kaskaskia limestone.
The Burlington limestone is made up to a considerable extent of Crinoidal
remains, and has afforded many fine species. The Warsaw limestone is some¬
times called the Lower Archimedes limestone, from the species of Archimedes,
which is common in it near Warsaw and elsewhere. The Keokuk and Warsaw
limestones are not separated in Missouri by Swallow, who makes the united
thickness in some places 200 feet: he names the whole the Archimedes lime¬
stone. The St. Louis limestone is partly a breeciated rock, but generally a light-
gray, fine-grained limestone, and is remarkable for the fine species of Melonites
(fig. 536), and also the coral Lithostrotion Canadense (figs. 521, 522). The Kas¬
kaskia limestone has been styled the Upper Archimedes limestone: it contains
many Crinids, especially of the genera Poteriocrinus, Zeacrinus, and Seaphio-
crinus (Hall). The Burlington limestone extends two hundred miles farther
north in the Mississippi .valley than the succeeding limestones.
To the south, in Kentucky and Tennessee, the subdivisions of these limestones
disappear, and cannot be well made out even by the fossils.
308
PALAEOZOIC TIME CARBONIFEROUS AUE.
In Illinois, the Burlington limestone is underlaid by the " Kinderhook Group,"
also Subearboniferous, consisting of sandstone and shole with some local beds
of limestone, the whole about 100 feet thick. (Worthen.) In Missouri, the
Chouteau and Lithographic limestones are regarded by some as equivalents of
this inferior group of the Subearboniferous, rather than of the Upper Devonian
to which they have been referred. ,
In Tennessee, the lower Subearboniferous beds are siliceous, as already men¬
tioned. In eastern Tennessee (which borders on the Appalachian region), this
lower or Siliceous Group consists of shales and sandstones many hundred feet
thick; in middle Tennessee, it is a siliceous rock 200 to 300 feet thick, more or
less calcareous, with some cherty layers, especially to the south, and also inter¬
calated beds of Crinoidal limestone. These siliceous beds reach south into Ala¬
bama. The upper group in Tennessee, though mainly limestone, has in some
parts near its middle a band of sandstone 50 to 100 feet thick.
The Michigan Carboniferous area appears to have been an independent basin
at the time of the formation of the rocks. There are four groups of strata, ac¬
cording to Winchell: the first, or lower, 171 feet of grits and sandstones, which
he has called the Marshall Group ; the second, 123 feet of shales and sandstones,
called the Napoleon Group; the third, 181 feet of shales and marl, with some
limestone and gypsum, called the Michigan Salt-group ; the fourth, the Carboni¬
ferous limestone, 66 feet thick. This limestone is well exposed at Grand Rapids.
In Ohio, the " Waverly sandstone," usually referred to the Upper Devonian,
has been referred in part at least to the Subearboniferous, and it probably
corresponds in horizon with the " Marshall Group" of Michigan and the " Kin¬
derhook Group" of Illinois. According to this conclusion, there is at the base
of the Subearboniferous a series of fragmental rocks over a very wide region.
A Subearboniferous limestone occurs near Lake Utah, in lat. 10° 13' N., long.
112° 8' W., containing the characteristic Archimedes. It is an exception to the
general fact that the limestone of this age in the Rocky Mountains belongs to
the second or Carboniferous period.
(b.) Appalachian region.—The rocks of the lower group in the Appalachian
region directly overlie the Devonian and Catskill beds, and are, in the main,
coarse grayish conglomerates and sandstones; those of the upper group are
soft shales mostly of a red color.
The loiver group has its greatest thickness in Pennsylvania and Virginia, being
2000 feet thick near Pottsville. Through much of the anthracite coal basin it
constitutes the encircling hills, as around the Wyoming basin, and in many
places forms a grayish-white band over another of red, the latter due to the
Catskill beds,—the two thus making a red and white frame, as Lesley says, around
the valleys or basins. It thins rapidly to the westward ; the rock retains its
whitish color and siliceous character in Virginia. Sandstone beds alternate
with the conglomerate; and in New York these finer layers abound in ripple-
marks, and that oblique lamination (fig. 61 e) which is due to contrary currents.
The shales of the upper group are soft, reddish, clayey beds, easily returning,
on exposure, to mud, the original condition of the material. They alternate
with sandstone layers, especially in the lower part. At Towanda, Blossburg,
Ralston, Lockhaven, Portage Summit, etc., in upper Pennsylvania, the formation
consists of two or three thick strata of shale separated by as many strata, 50 to
SUBCARBONIFEROUS PERIOD.
309
200 feet thick, of greenish sandstone. (Lesley.) Some thin layers consist of an
impure, rough-looking limestone.
This red-shale formation is 3000 feet thick at th'e Lehigh, Schuylkill, and Sus¬
quehanna Rivers; hut on crossing the Coal measures to the westward it rapidly
diminishes. At Broad Top it is less than 1000 feet ; at the Alleghany Mountain,
hardly 200; at Blairsville, 30 feet; and beyond, it is lost to view. (Lesley.)
The soft shales retain still the ripple-marks from the ancient waves, and rain¬
drop impressions from the showers of the day. The amphibian footprints
described beyond are from this formation.
Seams of coal occur in the Subcarboniferous at many places in Pennsylvania
and Virginia. In Montgomery co., Va., there is a layer of coal, two to two and
a half feet thick, resting on a bed of conglomerate : and 30 to 40 feet higher
there is another layer, six to nine feet thick, consisting of alternations of coal
and slate. These coal beds occur in the Lower group, and are covered by
the shales of the Upper. In Pennsylvania, there is a coal bed (and possibly
two) in the same Lower group) at Tipton, at the head of the Juniata, 600 feet
below the Upper shales : but, as far as known, it is a local deposit (Lesley).
The Subcarboniferous coal deposits are sometimes called false coal measures.
(c.) Eastern border region.—In Nova Scotia, the Subcarboniferous rocks are
red sandstones and red and green marls, with thick limestones full of fossils.
The estimated thickness is 6000 feet. To the north, towards the Azoic, the lime¬
stones fail, and, instead, the rocks are to a greater extent a coarse conglomerate.
To the south, limestones prevail. Beds of gypsum accompany the limestones.
The localities of these beds, mentioned by Dawson, are the Carboniferous
districts of northern Cumberland, Pictou, Colchester and Hants, Richmond
county and southern Inverness, Victoria, and Cape Breton.
In the lower part of these Subcarboniferous beds, as in those of Virginia,
there are, on a small scale, false coal measures, and in one instance a bed of erect
trees, under-clays, and thin coal seams; and the same beds contain numerous
remains of fish.
The fish-bearing shales of Albert Mine, New Brunswick, are referred to this
period by Dawson, from whom the above facts are cited. This mine affords a
peculiar pitch-like or asphaltic coal, which has been regarded by some investi¬
gators as a true coal seam much altered in the course of the violent folding and
metamorphic changes to which the rocks of the region, as all admit, have been
subjected; and by others as an inspissated mineral oil filling a fissure in the beds.
The coal is mentioned on p. 68, and analyses are given on the following page.
In Pennsylvania, two epochs may be distinguished in the Subcarboniferous,—
namely, the Alleghany, corresponding to the lower beds, and the Schuylkill, cor¬
responding to the upper beds. It is probable that the two divisions in Tennessee
(p. 308) are equivalents of these, and that the Alleghany epoch corresponds to the
lower of the Western Subcarboniferous limestones, the Burlington and Keokuk,
with the underlying beds.
310
PALAEOZOIC TIME CARBONIFEROUS AGE.
II. Life.
1. Plants.
The land-vegetation of the Subcarboniferous period was very
similar to that of the Lower Carboniferous, and descriptions of spe¬
cies are therefore not given in this place. It may have been as
profuse for the amount of land, although the circumstances were
less favorable for its growth and accumulation in marshes,—the
essential prerequisite for the formation of large beds of coal.
2. Animals.
The animal life was remarkable for the great profusion and
diversity of Crinoids,—or Sea-lilies, as they are sometimes called.
Some of the Crinoids—mutilated of their rays or arms, as is usual
with these fragile species—are represented in figs. 523-535. The
period might well be called the Crinoidal period in geological his¬
tory. Among the kinds, the Pentremites (figs. 530-532) are perhaps
the most characteristic. Instead of having a circle of arms, like
most Crinoids, the summit is closed up so as to look like a bud
(whence the name Blastoidea, applied to the family, from the Greek
pXactTog, a bud), and the delicate jointed tentacles are arranged along
the pseudo-ambulacral areas in vertical lines.
Among Corals, the auger-shaped Retepores called Archimedes are
characteristic. (See fig. 537.) They are properly Molluscan of the
tribe of Bryozoans. A true Polyp-Coral, eminently characteristic
of the period, is the Lithostrotion Canadense (figs. 521, 522). It is a
columnar coral, having a conical elevation at the bottom of each of
the cells, and grows often to a very large size.
Besides these, Brachiopods were numerous, especially of the
genera Spirifer and Productus. There were also many Cephalopods
of the genera Goniatites and Nautilus, and but few of the Orthoceras
family. Trilobites were rare; Selachian and Ganoid fishes very
abundant.
While the limestones of the West abound in fossils, the shales
and sandstones of the Appalachian region have afforded few of any
kind, and those mainly Conchifers and Gasteropods.
The most interesting are the tracks of an amphibian reptile,—
Sauropus primcevus Lea, the earliest American species known.
Some of the tracks from near Pottsville, Pa., are represented on
fig. 549. There is a succession of six steps along a surface little
over five feet long: each step is a double one, as the liind-feet
tread nearly in the impressions of the fore-feet. The print of the
SUBCARBONIFEROUS PERIOD.
311
fore-feet is something like that of a hand with five stout fingers,
the whole four inches broad ; that of the hind-foot is similar, but
somewhat smaller, and four-fingered. The reptile was therefore
large; this is also evident from the length of the stride, which
was thirteen inches, and the breadth between the outer edges of
the footprints, eight inches. There is also a distinct impression of
a tail an inch or more wide. The slab is crossed by a few distant
ripple-marks (eight or nine inches apart), which are partially obli¬
terated by the tread. The whole surface, including the footprints,
is covered throughout with rain-drop impressions.
We thus learn that there existed in the region about Pottsville,
at that time, a mud-flat on the border of a body of water ; that the
flat had been swept by wavelets leaving ripple-marks; that the
ripples were still fresh when a large amphibian walked across the
place ; that a brief showier of rain followed, dotting with its drops
the half-dried mud; that the waters again flowed over the flat,
making new deposits of detritus, and so buried the records.
Characteristic Species.
1. Protozoans—Although the class of lihizojwds probably commenced
in the lowest Silurian, the earliest described species from an American rock is
the Rotalia Baileiji Hall, from the Carboniferous limestone of Indiana.
Sponges.—The hornstone of the Subcarboniferous limestones of Illinois
abounds in microscopic spicula of sponges, along with a few Desmids similar in
general to those of the Corniferous limestone (p. 271). (M. C. White.)
2. Radiates—(«.) Polyps.—Figs. 521, 522, Lithostrotion Canadcnse CasteF
Fig. 521. Fig. 522.
Figs. 521, 522, Lithostrotion Canadense.
neau (L. mamillare of some authors,—among whom Milne Edwards, after thus
naming it, makes a correction in a note), from the St. Louis limestone.
812
PALJEOZOIC TIME CARBONIFEROUS AGE.
(b.) Echinoderms : Crinoids.—Fig. 530, Pentremites piriformis Say ; figs. 531,
532, P. Godonii Dc France (P.Jlorcalis, in part;,—both from the Kaskaskia lime¬
stone; fig. 523, Poteriocrinus Missowriensia Shumard, from the St. Louis lime-
Figs. 523-535.
Fig. 523, Poteriocrinus Missouriensis; 524, Actinocrinus proboscidialis; 525, A. unicornis;
526, Zeacrinus elegans; 527, Actinocrinus Christyi; 528, Platycrinus Saffordi; 529, the
proboscis of Actinocrinus longirostris; 530, Pentremites pyriformis; 531, 532, P. Godonii
(florealis); 533, Arcbaeocidaris Wortheni; 534, 534 a, A. Shumardana; 535, A. Norwoodi.
stone; fig. 524, Actinocrinus proboscidialis II.; fig. 525, A. unicornis Owen &
Shumard; fig. 526, Zeacrinus elegans II.,—this and the two preceding from
the Burlington limestone; fig. 527, Actinocrinus Christyi Shumard, the arms
fallen off,—from the Encrinal limestone of Missouri; fig. 529, proboscis of
Actinocrinus longirostris H.; fig. 528, Platycrinus Saffordi Troost, side-view,
from Burlington. Most of the above Crinoids have lost their arms and
pedicels.
Echinoids.—Fig. 533, Archxocidaris Wortheni II., of the St. Louis lime¬
stone; fig. 534, A. Shumardana H., of the Warsaw limestone, — a spine,
SUBCARBONIEEROTJS PERIOD.
813
enlarged; fig. 534 a, a plate of the same species, enlarged about two dia¬
meters; fig. 535, a plate of Arehseocidans Norwoodi H., natural size, from
Fig. 536.
Palseechinus (Melonites) multipora (X^)>
Outline view of the restored
Melonites.
Ambulacra! plates,
enlarged.
Fig. 536 a.
the Kaskaskia limestone; fig. 536, Melonites multipara, from the St. Louis
limestone, half natural size, but crushed; 536 a, an outline, showing the
form of the unbroken shell. The genus Arcliseo- j,.
cidaris, like the modern Cidaris, has large promi- ,—^r—%*•- .. •
nences on the plates to support the spines, which ™ |i| I *^||l§fl
are also large. In Melonites and Palseechinus the J ||k g) j
plates are without prominences, and the spines 1 X l!H |»
were small. The Pentremites above mentioned occur ( B M f
through nearly all the limestone or upper group in I it W J
Tennessee. ^®
3. Mollusks.—(a.) Bnjozoans.-— Fig. 537 a,
Archimedes reversa, being a portion of the spiral }•> f <7 ^
axis with the reticulated expansion removed. Fig. V |r I S
537 h, a portion of the reticulated expansion of A. & ?»
Wnrtheni, magnified and showing the non-poriferous jp tl° |»
surface. Fig. 537 c, the poriferous side of the same. it * if
(h.) Brachiopods.— Fig. 538, Chonetes ornata vJsjpJicJ'
Shumard (nat. size), fiom the Lithographic and Fig. 537 a, Archimedes reversa;
Chouteau limestones, Missouri; 538 «, enlarged sur- 537 h, c, A. Wortheni.
314
PALAEOZOIC TIME-
I CARBONIFEROUS AGE.
face-markings of same; fig. 539, Spirifer biplicatus H., from Burlington and
Quincy, Illinois; fig. 540, Orthis Michelini (var. Burlingtonensis H.), from
the Burlington limestone; Orthis (Strepto-
rhynchus) Umbraculum (fig. 550); fig. 541, Spi¬
rifer octoplicatus ; fig. 542, <S)j. bisulcatus (in-
trebescens II.); fig. 543, Retzia Verneuilana H.;
fig. 544, Chonetes variolata A. d'Orbigny; fig.
544 a, hinge-line of same, and aperture closed
by a pseudo-deltidium; fig. 545, Productus
pnnctatus Martin ; also P. Flemingit Sowerby,
P. el cyans Norwood & Pratten, Spirifer in-
crassatus Eichwald, Sp. spinosus Norwood
& Pratten, from the Kaskaskia limestone, etc. The Spirifer incrassatus is con¬
fined in Missouri to the lower Archimedes limestone. Many of the other
Brachiopods occur not only in the Subcarboniferous beds, but also in the Car¬
boniferous. They are common also in Europe.
Figs. 540-545.
Fig. 540, Orthis Michelini, var. Burlingtonensis; 541, Spirifer octoplicatus; 542, Sp. bisul¬
catus; 543, Retzia Verneuilana; 544, 544a, Chonetes variolata; 545, Productus punc¬
tatus.
There are also Gasteropods of the genera Platyceras, Straparollus, Naticopsis,
Pleurotomaria, Machrocheilus, Loxonema, etc. The Cephalopods are of the
genera Nautilus, Orthoceras, Gyroceras (the Gyroceras Burlingtonensis, from
Burlington, Iowa, five inches in diameter), Goniatites, etc.
4. Articulates.—A few Trilobites of the genus Phillipsia.
5. Vertebrates.—Fishes of the Selachian genera Cochliodus, Cladodus,
Orodus, Carcharopsis (Pristieladodus), etc., besides others of the order of Ganoids.
Fig. 546 is a tooth (natural size) of Cochliodus nobilis Newberry & Worthen, from
Figs. 538, 539.
Figs. 60S, £38 a, Chonetes oruata;
539, Spirifer biplicarus.
SUBCARB0N1FER0US PERIOD.
315
Illinois, one of the Cestraciont sharks; it must have been of great size, far exceed¬
ing any reported from Europe. The corresponding plates of the C. contortua are
given in fig. 547, reduced to one-third natural size. Fig. 548 A, Cladodua apinoatu
Fig. 546.
Fig. 547.
1
Fig. 546, Cochliodus nobilis; 547, C. contortus (x Vi)-
Newberry & Worthen, from the St. Louis limestone, Missouri; a, section of the
same; fig. 548 B, Garcharopaia Wortheni Newberry, from Huntsville, Ala.; fig.
548 C, Orodua mamillaris N. & W., from the Warsaw limestone, Warsaw, 111.
Fig. 548.
Fig. 548 A, Cladodus spinosus; 548 B, Carcharopsis Wortheni; 548 C, Orodus mamillaris.
Reptiles.—Fig. 549, Tracks of Sauroptis primsevus, one-eighth natural size,
discovered near Pottsville, Fa., by Isaac Lea, who has published a memoir upon
them in very large folio, with a magnificent full-size engraving of the slab with
the footprints.
The Carboniferous limestones of Nova Scotia and New Brunswick con-
316
PALAEOZOIC TIME CARBONIFEROUS AGE.
tain some fossils that ally the Fauna more with the European than with
that of the Interior Continental basin of North America. Among them are
Fig. 549.
the Spirifer glaber (fig. 554) and Productus Martini, both of which are European
species.
III. General Observations.
Geography.—As in the first half of the Upper Silurian there
was a period—-the Niagara—when a sea profuse in life, and thereby
making limestones, covered a large part of the Interior Continental
basin ; and again in the early part of the Devonian age—the
Upper Helderberg period—the same conditions were repeated;
so in the early Carboniferous there was a similar clear and open
mediterranean sea, and limestones were forming from the relics of
its abundant population. In the period of the Upper Silurian
referred to, the living species were of a miscellaneous character,
Brachiopods, Crinoids, and Corals occurring in nearly equal pro¬
portions ; but in that of the Devonian, Corals were greatly predo¬
minant, and in that of the Carboniferous, Crinoids had as remark¬
able a pre-eminence. By an open sea is meant one having free
connection in some part with the ocean; and this connection must
have been on the south, towards the Mexican Gulf; for the arena¬
ceous deposits of the wide Appalachian region show that there was
not, probably, a direct opening eastward into the Atlantic. The
mediterranean sea alluded to was, in fact, only an extension north¬
ward of the Mexican Gulf.
These interior waters in the Subcarboniferous period had nar¬
rowed limits on the east; for they no longer spread over New York,
SUBCARBONIFEROUS PERIOD.
317
and probably they hardly passed the western boundary of Ohio.
The Silurian area stretching southwestward from Cincinnati, men¬
tioned on a former page (p. 228), may have been a barrier between
the eastern and western waters. The absence of the limestone
from that region and from among the Subcarboniferous strata in
eastern Ohio (where it seems replaced by sandstone) affords strong
evidence that the elevation about Cincinnati had previously taken
place. To the north in Michigan and south in Tennessee, the
earlier beds were shales and sandstones,—the former State being-
near the northern border, and the latter in proximity to the Appa¬
lachian region. In Michigan the strata are Saliferous, and the con¬
ditions of the Salina period of the Upper Silurian in New York
(p. 249) were probably there repeated. Over both of these districts
circumstances were afterwards changed—probably through a pro¬
gressing subsidence—from those favoring sedimentary accumula¬
tions to those characterizing the clear Crinoidal sea. But at the
same time that sinking was going on in these parts, a rising of
the sea-bottom appears to have taken place to the northwestward
in Iowa, as Hall has observed; since after the formation of the
Burlington limestone, the succeeding limestone in the series
has its northern limit 200 miles more to the southward, and the
others still farther south, indicating a contraction of the sea from
that direction. The greatest thickness of these limestones, more¬
over, is in Missouri, where it amounts to 900 feet, or, with the inter¬
calated arenaceous beds, to 1200 feet.
It may be again repeated, that no great depth of water was re¬
quired for the Crinoidal sea.
The Appalachian region, as in past time, was one of extensive ac¬
cumulations of conglomerates, sandstones, and shales. Nearly 0000
feet of rock—five times the greatest amount in the West—were
formed in the course of the period. The thickness of the forma¬
tions, both in the East and West, is an approximate measure of the
amount of subsidence in each. In its more southern part (from
Virginia southward), however, there were limestones in progress as
in the interior sea.
The Eastern border region is a repetition in many points, though
on a smaller scale, of the more western portion of the continent.
The resemblance of the fossils to the European, according to Dawson,
implies a more direct connection through the Atlantic with the
eastern continent than existed between Europe and the Interior
basin.
318
PALAEOZOIC TIME CARBONIFEROUS AGE.
FOREIGN SUBCARBONIFEROUS.
The Subcarboniferous period was a time of limestone-making
also in Britain and Europe. There is proof, therefore, of a wide
extension of those geographical conditions that characterized Ame¬
rica,—that is, of an extensive submergence of the continental lands,
as a prelude to the period of emergence and terrestrial vegetation
that followed.
The limestone is often called the " mountain limestone." It
occurs in southern England and Wales, over large areas in Russia,
in Germany, Belgium, France, Spain, etc. In Ireland the thickness
is stated as varying between 1200 and 6400 feet. In the Hartz
there are slates and sandstones of the same age.
Life.
Plants.—Small coal-seams and many species of coal-plants occur in
the strata. The plants are related to those of the lower Coal measures,
and are, for the most part, the same in species. In some places, as
in northern Scotland, the rocks of the Subcarboniferous and Car¬
boniferous periods so run together, by the intercalations of lime¬
stones with the latter, that they have not yet been well distin¬
guished. The plants are further considered under the Carbonife¬
rous period.
Animals.—The " mountain limestone," like the American beds,
is noted for its Crinoids; its Brachiopods of the genera Productus and
Spirifer; its Corals of the genus Lithostrotion ; its Ganoid Fishes and
Sharks; its few Reptilian relics; and also for the absence of Trilo-
bites of all the old genera.
Characteristic Species.
The following are a few of its characteristic species. Fig. 550, Streptorhynchm
(formerly Ortliis) Umbraculum (common in the American Carboniferous); fig. 551,
Fig. 550, Streptorhynchus Umbraculum; 551, Athyris lamellosa; 552, Terebratula hastata.
Athyris (Sjtirigera) lamellosa ; fig. 552, Terebratula hastata; fig. 553, Product>"■
SUBCARBONIFEROUS PERIOD.
319
longispinus ; fig. 554, Spirifer glaher. Spirifer speciosus and ChonetesDalmaniana
are common species. Pleurotomaria carinata retains its original colored markings,
as first observed by the late Professor Forbes; and this author hence inferred that
Figs. 553-555.
Fig. 553, Productus longispinus: 554,Spirifer glaber; 555, Nautilus (Treniatodiscus) Kouinckii.
it was a shallow-water species, as only such have shells figured with colors.
Fig. 555, Nautilus (Treniatodiscus) Kouinckii.
Trilobites occur of the only three Carboniferous genera, Phil-
lipsia, Griffitliides, and Brachyrnctopus. Fig. 556 is Phillipsia
seminifera.
Remains of fishes are very common in Europe and Britain.
Among Cestracionts (or sharks with pavement-teeth) there are
Cochliodus contortus (fig. 547); among Hybodonts (or sharks
with regular teeth, the teeth with obtuse or rounded edges) there
is the Cladodus marginatus. Fig. 557 represents a small spe¬
cimen of one of the great fish-spines of this period, called Cte-
nacaiithus major by Agassiz. One specimen has a length of
fourteen and a half inches, and was probably eighteen inches in
the living Cestraciont. The old fishes, as Agassiz observes, must
have had gigantic dimensions, if we may judge from the size
of the spines.
Fig. 557.
Part of a spine of Ctenacantbus major.
Another spine, Oracanthus Milleri, Agassiz, is nine and a half inches long and
three inches wide at base, and yet it has lost some inches at its extremities. These
Fig. 556.
Phillipsia semi-
nifera.
320
PALAEOZOIC TIME—CARBONIFEROUS AGE.
specimens, and numerous other remains of fishes, are found in a fish-bone bed in
the mountain limestone at Bristol, England, and also in the same rock at Armagh,
Ireland. The British and European species, although numerous and often large,
do not exceed in either respect those which have been already found in con¬
nection with the Subcarboniferous beds of the United States.
DISTURBANCES PRECEDING THE CARBONIFEROUS
PERIOD.
It was remarked on page 305 that the Devonian beds are very
generally conformable with the Subcarboniferous, and therefore
afford in but few places indications of uplifts before the Subcar¬
boniferous period and its formations began. There is the same con-
formability for the most part between the Carboniferous and Sub¬
carboniferous ; yet the examples of the absence of it are more
numerous, and cover some wide regions. Through the investiga¬
tions of Norwood, Daniels, Foster, and Hall, it is now known that
the Coal measures of Iowa, Missouri, and Illinois rest unconform-
ably upon the strata beneath, and Hall observes " that this is so
whether these strata be the Subcarboniferous, Devonian, Upper
Silurian, or Lower Silurian." The want of conformability is very
distinct in certain parts, and but slight in others ; and in some cases
it is apparent only in the marks of extensive surface-denudation
which took place at some time preceding the Coal period.
In the annexed sections, the coal beds rest on tilted Silurian
strata. Fig. 558 is a section in northern Illinois. The Coal mea¬
sures here overlie the Lower Silurian; a, calciferous sandrock; b,
Fig. 558.
d.
' z- ' b
St. Peter's sandstone (Chazy ?); c, Trenton and Galena limestone ; d,
Coal measures. (E.W. Daniels.) Fig. 558 A was taken at Port Biron,
Rock Island co., Illinois, and shows the Coal measures A, resting
unconformably on the Niagara lime¬
stone B. (Worthen.) In this region, fifiS A'
the strike of the uplift is parallel to
the course of the Rocky Mountains,
or nearly northwest. A portion of
these uplifts directly preceded the Coal period. But others may be
of earlier date; for where the tilted rocks underneath are Silu¬
rian or Devonian instead of Subcarboniferous, it is not yet certain
CARBONIFEROUS PERIOD.
321
at what epoch the disturbance took place; and it may have long
preceded the Carboniferous age. More investigation is required to
fix the date.
No example of Carboniferous beds lying unconformably on tilted
Subcarboniferous beds has yet been observed in Pennsylvania, Vir¬
ginia, or New Brunswick.
In Great Britain, Russia, and the most of Europe, the Carbonife¬
rous and Subcai*boniferous beds, when occurring together, are con¬
formable. But in central and southern France, as Murchison says,
the two are always unconformable. In Bavaria, also, at Hof, the Sub-
carboniferous limestones and Devonian follow one another regularly,
though inclined together at a large angle; while the coal fields of
Bohemia lie in horizontal strata over their tilted edges.
2. CARBONIFEROUS PERIOD (14).
Epochs.—1. Epoch of the Millstone grit; 2. Epoch of the Coal
measures.
1. EPOCH OF THE MILLSTONE GRIT (14 a).
I. Rocks: kinds and distribution.
The Carboniferous period opened with a marked change over the
continent. The Subcarboniferous limestones and shales which
were formed upon the submerged land became covered with ex¬
tensive gravel or pebble beds, or deposits of sand ; the beds of that
epoch, hardened into a gritty rock, make up the millstone grit and
sandstone which underlie the Coal measures.
Similar conglomerates and sandstones were formed afterwards in
the course of the Coal measures; but this rock is prominent for its
extent, and for marking the commencement of the Coal era.
The Coal period in Britain has in general the same kind of intro¬
duction : the term Millstone grit applied to the rock comes to us
from England.
This Millstone grit extends over parts of some of the southern
counties of New York, with a thickness of 25 to 60 feet; and, owing
to the regularity of the joints, it stands out in huge blocks, walls,
and square structures, that have suggested such names as " Rock
City" and " Ruined City" (Cattaraugus and Allegany cos.). It
occurs through all the Coal areas of Pennsylvania, both the eastern
and western; it is from 1000 to 1500 feet thick about the centre
of the anthracite region, and diminishes rapidly to the westward.
It stretches southwestward through Virginia to Alabama.
22
322
PALAEOZOIC TIME CARBONIFEROUS AGE.
West of the Appalachian region, the rock is in part a pebbly
sandstone, but often only a fine-grained, arenaceous rock ; and from
some portions of the Mississippi basin it is absent.
Thin beds of coal occur in these conglomerates, and in certain
localities they are of workable extent.
(a.) Interior Continental basin.—In Ohio, Indiana, and Illinois, there are 40 to
100 feet of pebbly sandstone; in eastern Kentucky, a sandstone, which is 50
feet thick on the Ohio and 250 on the borders of Tennessee; in western Ken¬
tucky, a conglomerate, called the Caseyville conglomerate. It is probable that
these conglomerates and sandstones, referred to the beginning of the Coal mea¬
sures, belong to this initial epoch of the period. In Arkansas, the novaculite
used extensively for hones, and also great numbers of quartz crystals, occur
in beds referred to this epoch.
(b.) Appalachian region.—The grit in Pennsylvania is mostly a whitish sili¬
ceous conglomerate, with some sandstone layers and a few thin beds of carbona¬
ceous shale: it overlies the Subcarboniferous shale or sandstone. At Tamaqua,
the thickness is 1400 feet; at Pottsville, 1000 feet; in the Wilkesbarre region,
200 to 300 feet; at Towanda, Blossburg, etc., where it caps the mountains, it is
50 to 100 feet thick. (H. D. Rogers.)
In Virginia, the thickness is in places nearly 1000 feet: the rock is mainly a
sandstone, but contains heavy beds of conglomerate. The conglomerate of the
Subcarboniferous, in a similar manner, becomes an arenaceous rock in Virginia.
In Alabama, the rock is a quartzose grit of great thickness: it is used for mill¬
stones.
(c.) Eastern border region.—In the Nova Scotia and New Brunswick Coal region,
a millstone grit has been observed in the Carboniferous district of northern
Inverness and Victoria; but only sandstones overlying gypsiferous rocks in
Pictou co., and shales and sandstones at the Joggins.
2. EPOCH OF THE COAL MEASURES (146).
I. Distribution of the Coal Areas.
The Carboniferous areas of North America have been pointed out
on p. 305. The regions corresponding to the Coal period (black
areas on the map, p. 133) are—
1. The great Appalachian coal field, covering parts of Pennsylvania.
Ohio, Virginia, eastern Kentucky, eastern Tennessee, and Alabama.
The workable area is estimated at 60,000 square miles. The whole
thickness of the formation is 2500 or 3000 feet: aggregate thick¬
ness of the included coal beds, over 120 feet in the Pottsville and
Tamaqua valley, about 62 feet near Wilkesbarre, 25£ feet at Pitts¬
burg. The area is partly broken up into patches in Pennsylvania,
as shown in the following map. In the centre of the State, between
Pottsville and Wyoming, are the famous anthracite beds, divided
CARBONIFEROUS PERIOD.
323
into many distinct patches; and in the western part commences
the great bituminous coal field which spreads into Ohio and stretches
on south to Alabama.
2. The Illinois and Missouri, covering a very considerable part of
Illinois, part of Indiana and Kentucky, and, west of the Missis¬
sippi, portions of Iowa, Missouri, Kansas, and Arkansas. Esti¬
mated area, 60,000 square miles. Whole thickness of the formation,
in Missouri, 600 to 1000 feet; in western Kentucky, nearly 3300feet,
—with about 70 feet for the aggregate thickness of the coal beds.
3. The Michigan, situated about the centre of the peninsula.
Estimated area, about 5000 square miles. Whole thickness of the
324 PALAEOZOIC TIME—CARBONIFEROUS AGE.
formation, 123 feet; rests upon a sandstone, probably of the Mill¬
stone grit epoch, which is 105 feet thick.
4. The Texas, covering several of the northern and northwestern
counties.
5. The Rhode Island, lying between Providence and Worcester
in Massachusetts, and opened at Cumberland north of Providence,
at Portsmouth 23 miles south, and also showing thin seams at
Newport and elsewhere; in Massachusetts, outcropping at Mans¬
field 15 miles northeast of Providence, at Wrentham 5 miles
from Mansfield, and at Worcester. Estimated area, 1000 square
miles.
6. The New Brunswick and Nova Scotia, covering part of New Bruns¬
wick, Nova Scotia, Prince Edward's Island, and Newfoundland. Esti¬
mated area, 18,000 square miles. Whole thickness of the formation
at the Joggins, including the beds of the Mill-stone grit epoch,
14,570 feet: the number of included coal beds is 76, some of them
being very thin, and the aggregate thickness 45 feet. (Logan.)
These coal beds are situated in a part of the Coal measures, 2819
feet thick, near the middle of the series. At Pictou there are six
beds of coal, with an aggregate thickness of 80 feet. (Dawson.)
The total number of square miles of all the productive coal fields
of the United States is 125,000.
Besides the above, there is the Arctic Coal region, which has been
observed on Melville and Bathurst Islands, Banks Land, etc., and
the Rocky Mountains, both of which are yet unexplored.
Limestones of the Carboniferous period—formerly supposed to be Subcarboni-
ferous—have a wide distribution over the summit and both the eastern and
western slopes of the mountains. This limestone has been observed at the
Black Hills in Dakota, and the Laramie Range; about the head-waters of the
Missouri; at the South Pass of the Rocky Mountains; in the ranges south of
Pike's Peak, and east and west of Santa Fe, New Mexico; in the great basin
of the Colorado; and it probably underlies to a considerable extent the Meso-
zoic rocks of the Rocky Mountain slopes west of the Mississippi.
H. Rocks.
1. Kinds of rocks, and stratification.—The Coal measures include stra¬
tified rocks of all kinds,—sandstones, conglomerates, shales, shaly
sandstones, limestones; and the limestones are generally impure,
or magnesian. There is the same wide diversity that occurs in the
Devonian, with more numerous and rapid transitions than were
common in that age. Moreover, the rocks differ much in different
regions.
The Coal beds are additional layers in the series, interstratified
CARBONIFEROUS PERIOD.
325
with the shales, sandstones, conglomerates, and limestones. But
they are thin, compared with the accumulation of rock-strata.
The Coal measures contain, generally, 50 feet or more of beds of
rock to one foot of coal.
Iron-ore beds also occur, making other thin layers in the series,
and rendering the Coal regions the best iron regions of the globe.
The following section is an example of the alternations (beginning below):—
1. Sandstone and conglomerate beds 120 feet.
2. COAL 6 "
3. Fine-grained shaly sandstone 50 "
4. Siliceous iron-ore "
5. Argillaceous sandstone 75 "
6. COAL, upper 4 feet shale, with fossil plants, and below a thin
clayey layer 7 "
7. Sandstone 80 "
8. Iron-Ore 1 "
9. Argillaceous shale 80 "
10. Limestone (oolitic), containing Producti, Crinoids, etc 11 "
11. Iron-Ore, with many fossil shells 3 "
12. Coarse sandstone, containing trunks of trees 25 "
13. COAL, lying on 1 foot slaty shale with fossil plants 5 "
14. Coarse sandstone 12 "
The alternations are thus various, and may follow any order.
The shales, sandstones, conglomerates, and limestones resemble
the corresponding rocks of other periods, and they are distinguished
as belonging to the Coal measures only by the fossil plants or animal relics
they may contain. Disastrous errors are often made when this rule is
not regarded.
The beds, even when thick, whether of coal or of any of the
rocks mentioned, have in some districts a limited lateral extent;
yet in this respect the Coal measures differ little from earlier forma¬
tions. Some of the larger beds of coal are supposed to spread con¬
tinuously over many thousand square miles of area.
In connection with the Coal measures of Rhode Island there are extensive
beds of quartzose conglomerate, which outcrop at Newport and elsewhere, and
form a bold feature in the landscape at " Purgatory," 2J miles east of Newport.
They occur also in Massachusetts, between this region and Boston, showing
well about Roxbury. The exact position of the beds in the series is not
known, as the rocks have undergone great disturbance, and in some places so
much metamorphism that the cementing material is a talcose schist. At Taun¬
ton, Mass., its pebbles have occasionally been found to contain Lingulae of the
Potsdam sandstone {Lingula prima), proving that they are pebbles of this Pri¬
mordial rock ; but whence derived is unknown.
326
PALAEOZOIC TIME CARBONIFEROUS AGE
Besides the rocks mentioned, a buhrstone occurs in beds several
feet thick, in Ohio. It is a cellular, flinty, siliceous rock, valued
highly for millstones.
The limestones are more extensive in the Coal measures of the
Mississippi basin than in those of Pennsylvania and Virginia;
while, on the contrary, conglomerates are much less common in
the West. This accords with the fact, learned from the earlier
ages, that the Appalachian region is noted for its conglomerates
and sandstones, and the Interior basin for limestones.
In Wayne co., in western Pennsylvania, there are 80 feet of limestone in 350
feet of Coal measures; and near Wheeling, on the Ohio, twice this thickness of
limestone. In Missouri, there are 150 feet or more of the former to 650 of the
latter. In the lower 150 feet of the Missouri section there are, however, but
8 feet of limestone, and in 900 feet of the Lower Carboniferous in western Ken¬
tucky, only 10 feet. The limestones included among the strata appear often to
have a limited lateral range, instead of the uniformity over extended areas
common in earlier periods.
The rock underlying a coal bed may be of either of the kinds
mentioned; but usually it is a clayey layer (or bed of finer clay)
which is called the under-clay. This under-clay generally contains
fossil plants, and especially the roots of Carboniferous plants called
Stigmaria, and it is regarded (as first shown by Logan) as the old
dirt-bed in which the plants grew that commenced to form the
coal bed. In some cases trunks of trees rise from it, penetrating
the coal layer and rock above it.
The Nova Scotia Coal region abounds in erect trunks, stand¬
ing on their old dirt-beds, as illustrated in fig. 5G0 (by Dawson).
Fig. 560.
Section of Coal Measures at the Joggins, Nova Scotia (with erect stumps in the sandstone,
and rootlets in the under-clays).
Each of the 76 coal seams at the Joggins has its darker clayey
layer, or dirt-bed, beneath. In 15 of them there is only a trace of
CARBONIFEROUS PERIOD.
327
coal; but these, as well as the rest, contain remains of roots (Stig-
viarice), and often support still the old stumps. (Dawson.)
The rock capping a coal bed may be of any kind, for the rocks
are the result of whatever circumstances succeeded ; but it is
common to find great numbers of fossil plants and fragments of
trees in the first stratum.
The shaly beds often contain the ancient ferns spread out between
the layers with all the perfection they would have in an herba-
rium, and so abundantly that, however thin the shale be split, it
opens to view new impressions of plants. In the sandstone layers,
broken trunks of trees sometimes lie scattered through the beds.
Some of the logs in the Ohio Coal measures, described by Dr. Hil-
dreth, are 50 or GO feet long and 3 feet in diameter.
The thickness of the coal beds at times hardly exceeds that of
paper, and again is from 30 to 40 feet. The beds also vary in purity,
from coal with but 1 per cent, of earthy matter, to dark-colored
shales with only a trace of coal. The thickness is seldom over 8
feet, and the impurities ordinarily constitute from 7 to 15 per cent.
The Pittsburg seam, at Pittsburg, Pa., is 8 feet thick. It borders
the Monongahela for a long distance, the black horizontal band
being a conspicuous object in the high shores. It may be traced,
according to Rogers, into Virginia and Ohio over an area at least
225 miles by 100; and even into Kentucky, according to Lesquereux.
But it varies in thickness, being 12 to 14 feet in the Cumberland
basin, 6 feet at Wheeling, 5 at Athens, Ohio, and on the Great
Kanawha; farther south, at the Guyandotte, 2 to 3 feet.
The "Mammoth Vein," as it is called, which is exposed to view
at Wilkesbarre, Pa., is 29J feet thick. It is nearly pure through¬
out, although there are some black shaly layers 1 to 12 inches
thick. The same great bed is worked at Carbondale, Beaver Mea¬
dows, Mauch Chunk, Tamaqua, Minersville, Shamokin, etc.
At Pictou, in Nova Scotia, one of the coal beds has the extra¬
ordinary thickness of 37J feet, and a second 22feet.
2. Structure of the Coal.—A bed of coal, even when purest, consists
of distinct layers. The layers are not usually separable, unless the
coal is quite impure from the presence of clay; but they are
still distinct in alternating shades of black, and may be seen in
almost any hand specimen of the hardest anthracite, forming a
delicate, though faint, banding of the coal.
In much of the bituminous coal of the Mississippi basin a cross-
fracture shows it to be made up of alternate laminee of black,
shining, compact bituminous coal, and a soft, pulverulent car¬
bonaceous matter, much like common charcoal.
328
PALAEOZOIC TIME CARBONIFEROUS AGE.
The coal itself varies much in character. In some regions, as in
the Schuylkill (at Pottsville, Mauch Chunk, etc.) and Wilkesbarre
coal fields, at Peak Mountain, in Virginia, and in Ehode Island,
it is of the kind called Anthracite (see page 68), which is non-bitu¬
minous, and burns with very little bluish flame. At Pittsburg, and
through nearly all of the Appalachian coal field, and in the other
coal areas of North America, it is Bituminous coal, which burns
readily with a bright-yellow flame.
The bituminous coal is either the ordinary brittle kind, break¬
ing into lustrous angular pieces, or the compact Cannel coal, dis¬
tinguished by its firmness, slight lustre, conchoidal fracture, and
the absence of any laminated structure. Cannel coal often gra¬
duates into ordinary bituminous coal.
In many places there are vegetable remains in the coal itself,
such as impressions of the stems of trees, or leaves, or charcoal¬
like fragments which in texture resemble charcoal from modern
wood. Fig. 561 a represents a specimen of this kind from Tusca¬
loosa, Ala., as figured by Bunbury: it has a fibrous appearance to
the naked eye, but under a pocket-lens shows rectangular meshes
over the whole (fig. 561 b), like the structure of the leaves of some
water-plants.
Even the solid anthracite has been made to divulge its vegetable
tissues. On examining a piece partly burnt, Professor Bailey
Fig. 561. Fig. 562.
found that it was made up of carbonized vegetable fibres. The
annexed figures 562 a, b, c, are from his paper on this subject.. He
CARBONIFEROUS PERIOD.
329
selected specimens which were imperfectly burnt (like fig. 5G2 a),
and examined the surface just on the borders of the black portion.
Fig. 562 b represents a number of ducts thus brought to light, as
they appeared when moderately magnified, and fig. 5G2 c two of the
ducts more enlarged ; the black lines being the coal that remained
after the partial burning, and the light spaces silica. The ducts
were T'ffth of a millimetre (about four-thousandths of an inch)
broad. ±so stronger evidence could be had of the vegetable origin
of anthracite coal. Dawson reports like results with bituminous.
Pyrites (sulphuret of iron, page 64) is sometimes disseminated
through coal beds in nodules or seams, to the serious injury of the
coal. Such coal crumbles down on exposure to the air, and gives
forth sulphur fumes when burnt. Even the best of mineral coal
contains traces of pyrites; and to this is owing the sulphur smell
ordinarily perceived from coal fires.
3. Iron-ores.—The iron-ore beds are usually from a few inches to 3 or 4 feet in
thickness. They contain the ore in concretionary masses or plates of a stony
aspect. The most common but not most valuable kind has a grayish-blue
and drab color on a fresh surface of fracture, and differs from limestone in being
unusually heavy : this ore, called clay-ironstone, is an impure spathic iron or
chalybite (p. 03). Another variety of ironstone is an impure hematite (p. 05),
affording a red powder. Still another kind is an impure limonite (p. 05), having
a reddish-brown or yellowish-brown color and affording a brownish-yellow pow¬
der: beds of this variety are few, but widely extended, thick, and valuable.
4. Upper and Lower Coal Measures.—The Coal measures are sometimes divided
into the Upper and Lower Coal measures. The most convenient division is
above the "Mammoth bed" of Pennsylvania,—-as there is a marked change in
the flora from this point. It has been proposed to make the Mahoning sand¬
stone the dividing bed, above the Upper Freeport coal bed, which is the third
above the so-called Mammoth bed in the Pennsylvania series. Another great
sandstone stratum, called the Anvil Rock, occurs in Kentucky, above the twelfth
Coal bed in the Kentucky series; and this has also been made a dividing
stratum in the measures. There is nothing in the fossils that renders the sub¬
division at these places of geological importance. (Lesquereux.)
The great Anthracite region of Pennsylvania is largely Lower Carboniferous.
The Upper Carboniferous is present there (at Pottsville, Shamokin, and Wilkes-
barre) up to the top of the Pittsburg group (Lesley); but the rest docs not extend
so far eastward. The greatest development of the lower coal was in Pennsyl¬
vania; and of the upper, in the States farther west. The highest beds in the series
appear to occur west of the Mississippi, in Kansas, where they merge into the
Permian. There are, however, according to McKinley, 3000 feet of barren Coal
measures above the level of the Pittsburg coal, in the southwest corner of Penn¬
sylvania and the adjoining part of Virginia, and it is not certain how far
upward they may reach in the series.
5. Equivalency of the Appalachian and Illinois Coal Measures.—There is great
difficulty in arriving at safe conclusions as to the equivalency of the beds in
330
Palaeozoic time—carboniferous age.
the different coal basins, because the beds of rock as well as of coal—even those
that are the thickest—vary much at comparatively short distances over the
country. Moreover, as the basins are wholly disconnected, there is no chance
to trace even a single stratum from one to another. It is often assumed that
the Appalachian and Illinois beds were once united, and were afterwards
divided by the uplift of the Silurian about Cincinnati and extensive denudation
accompanying it. But it has been shown (p. 317) that this uplift probably
antedates long the Carboniferous Age; and, if this were so, the connection in
those latitudes is impossible. It is evident, therefore, that only the most general
conclusions on the subject of equivalency can be accepted as established facts.
The principal investigations on this subject are those of Lesquereux, who has
brought to it a thorough knowledge of the coal plants.
The Coal measures of Pennsylvania and the States west include twelve to
eighteen distinct workable coal beds, besides thinner seams, the number vary¬
ing in different regions from certain beds being comparatively local. In this
series there are two beds that have special prominence on account of their
thickness and the wide range they arc believed to have.
There are, first, the Mammoth Anthracite rein of Pennsylvania, which is the
second or third from the bottom, not far from the Millstone grit.
Second, the Great Pittsburg led, the seventh or eighth above the Mammoth vein.
The following are the equivalents of these beds, according to Lesquereux :—
(1.) Mammoth bed (Second workable Pennsylvania bed).—The bed at Leo¬
nards, above Kittaning, Pa. (3J feet thick), etc.; Mahoning Valley, Cuyahoga
Falls, Chippewa, etc., Ohio; the Kanawha Salines; the Breckcnridge Cannel
Coal and other mines in Kentucky, the first (or second) Kentucky bed; the
lower coal on the Wabash, Ind.; Morriss, etc., 111.
(2.) Pittsburg bed (Eighth Pennsylvania bed).—Bed at Wheeling; at Athens,
Ohio; the Well Coal, at Mulford's, in western Kentucky, the eleventh Ken¬
tucky bed.
The Gate and Salem beds, correspond to the Upper Frecport (or fifth bed, west¬
ern Pennsylvania); Pomeroy coal, Ohio, situated below the Mahoning sandstone;
the Curlew coal, of Curlew Hill, Kentucky, or the fourth Kentucky bed.
In Kentucky, fifteen or twenty distinct coal beds exist. The eleventh is sup¬
posed to correspond to the Pittsburg bed, and the others are above it. Above
the twelfth, there is the massive sandstone, 40 to 50 feet thick, called the Anvil
Pock, from the form of two masses of it in southwestern Kentucky. Six or
seven coal beds occur above the Anvil Rock, in about 500 feet of rock; but they
are very thin ; the whole amount of coal in this thickness is about 5 feet.
(D.D.Owen.) The thickness of rock in the Coal measures below the top of
the Anvil Rock is about 1000 feet, and of the included coal beds about 40 feet;
making, in all, for the western Coal measures of Kentucky, a thickness of 1500
feet, in which are 45 feet of coal.
6. Sections of the Coal Measures.—In western Pennsylvania, the western Coal
measures, to the top of the Upper Freeport Coal inclusive, consist, according to
Lesley,* of the following beds. The numbering of Lesley by the letters of the
* Manual of Coal and its Topography, by J. P. Lesley, 12mo, 1856, Phila¬
delphia. Lippincott & Co.
CARBONIFEROUS PERIOD.
331
alphabet is added; and also that by Lesquereux (the latter in parentheses), as
made out from a supposed parallelism between the Kentucky and Pennsyl¬
vania beds.
Feet.
Millstone Grit ?
1. COAL No. A, with 4 feet of shale [1 A] 6
2. Shale and mud rock 40
3. COAL No. B [1 B]. (Equivalent of Mammoth bed) 3-5
4. Shale, with some sandstone and iron-ore 20-10
5. Fossiliferous Limestone 10-20
6. Buhrstone and Iron-ore 1-11
7. Shale 25
8. COAL No. C. The Kittaning Cannel (equivalent of the Cannel of
Peytona, Va. and Darlington, Pa.) [2]
9. Shale,—soft, containing two beds of coal 1 to 1J feet thick 75-100
10. Sandstone 70
11. Lower Freeport COAL bed No. D [3] 2-4
12. Slaty sandstone and shale 50
13. Limestone 6-8
14. Upper Freeport COAL, No. E of Lesley [4] 6
15. Shales 50
The Upper Coal measures are continued in western Pennsylvania, to the Pitts¬
burg coal inclusive, as follow :—
Feet.
1. Mahoning Sandstone 75
2. COAL No. F [5] 1
3. Shale; thickness considerable ?
4. Shaly sandstone 30
5. Red and blue calcareous marls 20?
6. COAL No. G [6] 1
7. Limestone, fossiliferous 2
8. Slates and shales 100
9. Gray clayey sandstone 70
10. Red marl 10
11. Shale and slaty sandstone 10
12. Limestone, non-fossiliferous 3
13. Shales 32
14. Limestone 2
15. Red and yellow shale 12
16. Limestone 4
17. Shale and sand 30
18. Iron-ore (spathic) 25
19. Limestone 1-1 i
20. Pittsburg COAL, No. H of Lesley [11] 3-9
The upper part of the Upper Coal measures (above the Pittsburg bed) in
western Pennsylvania (Waynesburg, Greene co.), according to Lesley, includes,
commencing below :—
332
PALAEOZOIC TIME CARBONIFEROUS AGE.
Feet.
1. Shale, brown, ferruginous, and sandy 30
2. Sandstone, gray and slaty 25
3. Shale, yellow and brown 20
4. Limestone,—the Great Limestone south of Pittsburg (including two
COAL beds, 2£ feet and 1 foot) 70
5. Shale and sandstone 17
6. Limestone 1
7. Shale and sandstone 40
8. COAL 6
9. Shale, brown and yellow 10
10. Sandstone, coarse, brown 35
11. Shale 7
12. COAL 1J
13. Limestone 4 feet, shale 4, limestone 4, shale 3 15
14. Shale 10 feet, sandstone 20, shale 10 40
15. COAL 1
16. Sandstone (at Waynesburg), with 4 feet of shale 24
Sections of the strata of Kentucky, Missouri, Ohio, and Michigan, will be
found in the Geological Reports on those States, and others of Nova Scotia in
Dawson's Acadian Geology, and the Quarterly Jour. Geol. Soc. 1854, page 60.
Mr. Lesquereux has published a memoir on the equivalency of the coal beds of
the United States in the Geological Report of Kentucky.
The relations of the sandstones, limestones, and shales that alternate with
the coal beds over the wide region stretching from the Appalachians west, are
but partially understood. Although these strata seem to be generally limited
in range, there is still an equivalency to be ascertained for the whole succession.
The rocks, as in other ages, are consecutive records of the events of the period;
and until fully elucidated, the history of the American Carboniferous era will
remain imperfectly known.
III. Life.
I. Plants.
The abundance of Fossil Plants is the most striking charac¬
teristic of the Coal era; and the remains are so widely diffused,
and are distributed through so great a thickness of rock and coal,
that we may he sure we have in them a good representation of the
Forest and Marsh as well as Marine Vegetation of the Carboniferous
age. In the marine, there is little peculiar to note. The land-
plants, on the contrary, afford evidences of progress in the life of
the globe, and reveal an expansion of some departments of the
Vegetable kingdom which would not have been suspected were
it not for the evidence in the rocks
This vegetation began, as already shown, in the early Devonian,
and was well displayed before its close. The general characters
CARBONIFEROUS PERIOD.
333
of the flora have been mentioned on page 302. The tribes of
plants are here repeated in tabular form:—
1. Pha:nogams, or Flowering Plants ; the inferior class Gymno-
sperms. (See page 165 for the signification of the terms used in the
classification of plants.)
a. True Conifers.
b. Sigillarids, related to the Conifers.
2. Caramites, — plants with jointed stems or trunks, supposed
by Brongniart to rank nearer Gymnosperms than the Equiseta
among Acrogens.
3. Cryptogams, or Flowerless Plants; the superior class Acrogens.
a. Lycopodium or Ground-Pine family.
I. Ferns.
r
c. Equiseta.
The frontispiece may be again referred to for a general idea of the features
and also the characteristic plants of the Coal era:—the Lycopodium, a large tree
on the right of the picture, and another on the left; the Sigillaria, a broken
stump in the right corner; the Tree-fern, a tree with spreading top near the
centre of the picture, copied from a drawing of a modern species; ordinary
ferns, the low plants with spreading leaves or fronds beneath the Tree-fern, etc.,
in the foreground.
Eemains of Fungi (or Mushrooms) occur, but are not common ;
and these, with Sea-weeds (marine Algse), are the only kinds of
lower Cryptogams known to be present. There is no evidence of
the existence of Mosses, Lichens, or Liverworts (Iiepaticae). Even
the simple Confervse (fresh-water Algae), sometimes called frog-
spittle, were not in the ponds of the Coal-era.
There were no Angiosperms, and, in all probability, no Palms or
other Endogens.
A few remaining species of plants have been referred to the
Grasses, Sedges, and Palms, and some small Endogens related to
the Lily tribe. But these are rare and of uncertain determination.
The order of Palms has been supposed to be represented in the
genera Flabellaria, Noeggerathia, Palmacites, and Trigonocarpum; but the
species are now believed to belong to other groups.
Although the vegetation was very largely cryptogamous, yet it
was in a great degree forest-vegetation. Should we collect all the
existing terrestrial Cryptogams of North Ameiuca, in order to make
a forest of them, the forest would hardly overtop a man's head,
and the Ferns would have an undergrowth of toad-stools, mosses,
and lichens.
Tree-ferns now grow only in the tropics. The largest modern
334
PALAEOZOIC TIME CARBONIFEROUS AGE.
Lycopodia are four to five feet in height; the ancient were sixty to
eighty feet. The Equiseta of our marshes are slender, herbaceous
plants, with hollow stems, and, when of large size, little over two
feet high ; the Calamites of the Carboniferous marshes had partly
woody trunks, and some were a score of feet, or more, in height.
The Conifers of the period were abundant, and were the modern
feature in the Palaeozoic forests. But these were in the main
related to the Araucarian Pines (see p. 1GG),—a group which now
lives in Araucania, Chili, and Brazil, on the continent of South
America, and in Australia and Norfolk Island, in the South Pacific,
and which are therefore confined in the Age of Man to the Southern
hemisphere.
1. Lepidodcndron tribe (Lycopodium or Ground-Pine family). The
various genera (Lcpidodendron, Lepidophloios, Halonia, Knorria, etc.)
are confined to the Lower Coal measures. They were lofty woody
trees, with scarred trunks and branches, the scars of which (figs.
5G3, 4, 5, 7) are arranged in quincunx order. These scars are the
impressions left where the leaves or fronds dropped off, and are
very similar to those observed on the trunks of modern tree-
ferns, one of which is shown in fig. 575, and an ancient one in
fig. 5GG.
Figs. 564-566.
Fig. 563, view—partly ideal—of the extremity of a branch of a Lepidodendron.
The slender, pine-like leaves in the Lepidodendron Sternbergii, as shown in mag¬
nificent specimens from the coal-mines of Radnitz, in Austria, figured by
CARBONIFEROUS PERIOD.
bb 5
Ettingshausen, are over a foot long, and are as closely crowded about the
branches as in any modern Pine. See also the trees on the frontispiece, above
Pig. 563.
Extremity of a branch of Lepidodendron, with the
leaves attached.
referred to. Pig. 564, part of the surface of the Lepidodendron obovatum Stern¬
berg, a common species both in the United States and Europe. Fig. 565, L. ch/-
pentum. The cones (Lepidostrobux) found in the same rocks with the Lepidodendra
are regarded as their fruit. They have some resemblance to the cones of Pines.
Fig. 567 represents a portion of the stem of Halonia pulchella Lsqx., a plant
similar to Lepidodendron, from the Coal measures of Arkansas.
2. Sigittaria tribe.—The Sigillarice (figs. 568, 569) are most abundant
in the Lower Coal measures, and appear to have taken a great part
in the formation of the Coal. They are supposed to have grown
over the great marshes of the era in which the Coal vegetation
330
PALAEOZOIC TIME CARBONIFEROUS AGE.
accumulated, while the Lepidodendra and Conifers, though not ex¬
cluded from the marshes, covered the drier hills and plains of the
continent. Most of the Sigillarite grew up as simple trunks to a
height of thirty to sixty feet, without branches. The surface and
summit were covered with long, narrow leaves in great numbers;
and out of these leaves, found separate, the genera Poacites and
Cyperites have been made. The trunk is usually ribbed vertically,
and the scars are arranged along the ribs. The name of the genus
alludes to the scars, and is from the Latin sigilla, seals. In both
this group and the preceding, the appearance of the scars of the
same species varies much with age, and upon the opposite sides of
the bark the same scar is wholly different, as shown in figs. 568
and 569, in the part of each of which to the right an impression
of the inner surface of the bark is shown. The plant is proved
to have been of close texture through the interior of the trunk,
and still may have had a rapid growth. Stumps made hollow
by decay within, and now filled with sand and clay and fossilized,
are common in the Coal measures. Of many such, only casts in
sand, showing an impression of the scarred exterior, remain.
Fig. 568 represents the Sic/illaria oculata, from Trevorton, Pa.; 569, S. obovata,
from Pennsylvania and Kentucky.
3. Stigmariw.—The Stigmaricc were originally described as the re¬
mains of trees related to the Sigillarice. The surface-impressions are
very different, being simply scattered rounded depressions or pro¬
minences ; and to each there is sometimes a long, leaf-like append¬
age, as in fig. 570, which represents a portion of a branch. But the
branching roots of both Sigillarise and Lepidodendra have been
68
Figs. 568-570.
69
70
Fig. 568, Sigillaria oculata; 509, S. obovata; 570, Stigmaria ficoides.
CARBONIFEROUS PERIOD.
387
found to have the characteristics of the Stigmaria; and these roots
often lie in great numbers in the under-clays of the coal beds. In
Nova Scotia and England, Sigillaria stumps have been observed
with Stigmaria roots. Lesquereux, however, maintains that the
Stigmariee are sometimes, at least, stems, and not roots.
Fig. 570 is the Stigmaria ficoides, a species which is said to have a range
through the whole Coal measures,—which may be true if more than one species
be not confounded under the name. Sigillaria minuta occurs in the Catskill
epoch of the Devonian; other species, in the Upper Coal measures.
4. Catamites.—These jointed rush-like plants sometimes grew to a
height of twenty feet or more, and were associates of the Sigillarice
in the marshes, being common throughout the Coal measures.
Fig. 583 represents C. cannieformis, one of the Lower Coal-measure species.
C. Cistii Brngt. and C. nodosus Sehlotheim are other American Lower-Coal
species, as well as foreign; C. Pachydermia is found only in the Millstone grit
below (Lesquereux).
5. Conifers.—Coniferous trunks and stumps are common through
the Coal measures, and occur also far down in the Devonian. But
it is remarkable that their leaves have been seldom found. The
Sternbergice, which are abundant in Ohio, and at Pictou, Nova Scotia,
have been shown by Dawson and Williamson to be, in some cases,
casts of the pithy or open cellular interior of some Conifers. They
are thick, cylindrical stems, much wrinkled circularly, consisting
of the same arenaceous material as the rock in which they occur
buried. Occasionally they have a carbonaceous exterior, which is
the woody part of the former tree. In Nova Scotia specimens, as
well as those of England, a coniferous structure has been observed
in the coaly exterior, and also a very open cellular structure,
through the sandstone interior. One of the Devonian species from
Pictou is not distinguishable in its microscopic structure from the
Pinites (Dadoxylon) Brandlingi of Witham.
Most of the known Carboniferous species are related (Dadoxylon
included) to the genus Araucarites. The American species thus far
made out belong to the genus Dadoxylon (Dawson).
Fruits of Conifers and other plants.—Besides the remains of trunks
of Conifers, various fruits are found in the Carboniferous beds.
Those which have been referred to the genus Trigonocarpum, accord¬
ing to Hooker, are the fruit of Conifers, and resemble most that
of the Chinese genus Salisburia of the Yew family (Taxinea). Accord¬
ing to Dawson, they are the fruit of Sigillarise.
Figs. 571 to 574 (by Newberry) represent nuts or fruits from the Lower Coal;
fig. 571 a, b, c, d, is Trigonocarpum tricuspidatum Newberry; a, the nut; b, the
338
PALAEOZOIC TIME CARBONIFEROUS AGE.
kernel; c, the complete nut; d, the husk or rind enclosing the nut. Fig. 572 is
Cardiocarpum samarseforrne (the name of the genus, from /caption, heart, alludes to
Figs. 571-574.
Fig. 571 a, h, c, d, Trigonocarpum tricnspidatum; a, the nut; b, the kernel; c, the complete
nut; d, the husk or rind; 572, Cardiocarpum samarseforrne; 573, C. elongatum; 574, C.
bicuspidatum.
the common cordate form of the seed); fig. 573, C. elongatum ; fig. 574, 0. bicus¬
pidatum. The Cardiocarpa are supposed to be the fruit of Lepidodendra.
6. Ferns.—The ferns are mostly of the low herbaceous kinds, al¬
though a few tree-ferns occur. Some of the fronds were six to eight
feet in length.
In one group of Ferns, the Neuropteridse, the leaves or leaflets have no mid¬
rib. as in Gyclopteris, Nocggerathia, Odontopteris, and Neuropteris. In another
group, the Sjolienopteridee, the leaflets or lobes have a mid-rib slightly distinct,
but it fails before reaching the apex, and the veins do not emerge from it,
as in Sphenopteris and Hymenophyllites. In a third, the Pecopteridse, the mid¬
rib is very distinct, and the veins emerge from it more or less obliquely, as in
Alethopteris, Pecopteris, Callipteris, Asplenites.
Fig. 566 represents the scar on the surface of an American species of fossil
tree-fern, Oaulopteris punctata Lsqx., from the Gate vein,
Pennsylvania. For comparison, the scar of a modern tree-
fern, fig. 575, is here given, from the species Cyathea compta,
occurring in the islands of the Pacific. AVith the growth of
the tree (see sketch near middle of frontispiece), as new
fronds are unfolded, the old ones drop off, each of which
leaves its scar analogous to the above. The manner in which
the fronds of ferns unroll as they expand is shown in the
figure here referred to.
Fig. 576, Neuropteri8 Loschii Brngt., and fig. 577, Nen-
ropteris liirsuta Lsqx., from figures by Lesquereux, both very
common in the Upper Coal measures in Ohio and Kentucky,
and the former particularly abundant in the Pomeroy bed.
Fig. 579, Pecopteris arboreseens Brngt., common in Penn- Scar of a recent tree
sylvania and Ohio. P. Cyathea Brngt., and P. unita Brngt., fern (X 3^)•
Fiht. 51 o.
CARBONIFEROUS PERIOD.
339
are also common in the United States, occurring in the Rhode Island coal fields
as well as elsewhere. Alethopteris Serlii Gopp. is another common species of
the Upper Coal measures, which is found also in Europe. Fig. 580, Cyclopteris
chgcins Lsqx., found in the Shamokin Coal bed, Pennsylvania.
In Arctic America, on Melville Island, impressions of a Sphenopteria have
been observed in connection with the coal.
Figs. 576-583.
Fig. 576, Neuropteris Loschii; 577, Neuropteris hirsuta; 578, Sphenophylhim Schlothei-
mii; 579, Pecopteris arborescens : 579 a, a portion of the same, enlarged; 580, Cyclopteris
elegans; 581, Asteropliyllites ovatus, with the nutlets in the axils of the leaves; 582, A.
sublevis; 583, Calamites cannfeformis; 583 a, surface-markings of same, enlarged.
The genus Odontopteria is mostly of the Lower Coal measures. Fig. 584,
portion of a frond of 0. Schlotheimii, from Pennsylvania and Europe; the whole
frond is tripinnately divided, and of very large size. All the species of Hymeno-
, 340 PALAEOZOIC TIME—CARBONIFEROUS AGE.
phyllitea, and several of Alethopteris, Neuropteris, and Pecopteris, are found in
the lower division. Fig. 585, Alethopteris Lonchitidis, exclusively of the Lower
Coal. Sphenopteris triductylites Brgt. is also from the Lower Coal. Fig. 586,
Figs. 584-587.
Fig. 584, Odontopteris Schlotheimii; 585, Alethopteris Lonchitidis; 586, Hymenophyllites
Hildrethi; 586 a, portion of the same, enlarged; 587, Sphenopteris Gravenhorstii; 587 a,
portion of the same, enlarged.
Hymenophyllites Hildrethi, from the Kanawha Salines, and 586 a, the same, en¬
larged; fig. 587, Sphenopteris Gravenhorstii, common in Ohio and farther west,
at the Gate Vein, Pennsylvania, and occurring also in England and Silesia;
587 a, a portion of the same, enlarged.
The genus Noeggerathia, a Devonian species of which is figured on p. 291,
occurs in the Lower Coal measures alone. Fig. 587 A, Noeggerathia minor
Lsqx., from Pennsylvania.
CARBONIFEROUS PERIOD.
341
Another group of Coal plants is the Aster ophyllites family, having some
resemblance to Equiseta. It includes flexible herbaceous species, with leaves
arranged in a circle or whorl at joints in the stem, whence the name, from aarnp,
star. They are confined to the Upper Coal measures. In the genus Asterophyl¬
lites the leaves are slender; and in SpJienophyllum (from the Greek a icedge)
they are obtuse and wedge-shaped, being smallest at base. Fig. 582, Astero¬
phyllites suhlevis; fig. 581, A.ovatus, with the nutlets in the axils of the leaves;
fig. 578, Sphenopltyllum Schlotheimii Brngt., from Pennsylvania, Salem and
Gate veins, and Pomeroy beds, Ohio. Dr. Newberry regards some species of
Figs. 588-590.
both genera as parts of the same plant, the former the submerged part, and the
latter that which is emerged or rests upon the water. Annularia is another
genus of this family. One species of it is represented in fig. 616 B.
Figs. 588-590 represent branches, with what seem to be the remains of flowers
and fruit, discovered by Dr. Newberry in the Ohio Coal measures. Some speci¬
mens of this general character have been regarded by Hooker as young or par¬
tially-developed leaf-buds. It is, however, difficult, according to Dr. New¬
berry, to explain the specimens on that hypothesis.
The species of Coal plants of tlxe American coal fields, thus far
342
PALAEOZOIC TIME CARBONIFEROUS AGE.
observed, number about 350. 150 species have been procured from
a single coal bed in Ohio by Dr. Newberry.
Characteristic Species of some of the subdivisions of the Carboniferous.
Lesquereux enumerates the following among the species characteristic of
the groups below mentioned :—
(«.) Subcarboniferous beds.—Stigmaria Anabathra Corda, S. minor, S. undu-
hita, and others; Lepidodendron Veltheimianum Sternb., L. Worthianum;. a
Caulopterie; a Megaphytum; Catamites Suckowi Brngt.; a Bvrnia; Cordaites
borassifolia Ung., Knorria imbrieata Sternb. Of these, the first of them, with
the Catamites, Cordaites, and Lepidodendron Worthianum, occur higher in the
series, and the Catamites and Cordaites continue through the whole Coal mea¬
sures, or at least above the Pittsburg coal bed.
(b.) 3fillstone Grit.— Lepidodendron, six species; Sigillaria, two; Catamites,
two; Stigmaria ; and the Ferns, Pecopteris velutina Lsqx., P. nervosa Brngt.,
Neuropteris flexuosa Brngt., N. hirsute/, Lsqx., Annularia sphenophylloides Ung.,
Odontopteris crenulata, Hymenophyllites furcatus Brngt., Splienopteris latifulia
Brngt., which occur also higher, to at least Coal bed No. 1 B.
(c.) Mammoth Bed (No. 1 B).—A great number of fruits, including nearly all
of the Coal measures, of the genera Trigonoearpum, Cardioearpum, Rhabdocar-
pus, and Carpolithes; numerous Lepidodendra (eighteen species); Alethopteris
Lonehitidis, and A. marginata, not known above, and species of Cattipteris, with
few of the finer forms of the family, of the genus Pecopteris ; among which few
there are the Pecopteris velutina, P. Sillimani, P. plumvsa Brngt.; Splienopteris
family numerously represented,—e.g., S. latifulia Brngt., S. obtusiloba Brngt.,
S. glandulosa Lsqx., S. polyphylla Lindley & Hutton, S. Newberryi Lsqx., S. ar-
temisixfolia Brngt., and Hymenophyllites Hitdrethi Lsqx., and H. spinosus Gdpp.,
all peculiar to it; all the American species of Odontopteris, except 0. crenulata,
found also in the Millstone grit. Many Sigillarise, as S. stellata Lsqx., S. Serlii
Brngt., S. tesselata Brngt., S. Brocliunti Brngt., S. alreolaris Brngt., and others,
not found above. The most abundant species are the omnipresent Neuropteris
hirsuta and N. flexuosa. There are also species of Annularia, Sphenophyllum,
Asterophylliles, and Catamites; and everywhere Stigmaria ficoides.
(d.) Coal No. 4.—This bed is characterized by small Ferns. There are no
Lepidodendra, but some Sigillarise-, and numerous species of the Pecopteris
family; also species of Asteropliyllites, many of Neuropteris, and several of
Splienopteris.
(e.) Coal No. 11, the Pittsburg Coal bed.—There are Neuropteris hirsuta Lsqx.,
Cordaites borassifolia, Neuropteris flexuosa Brngt., Pecopteris polymorpha Brngt.,
P. arboresccns Brngt., P. Cyathea Brngt., Sphenophyllum emarginatum Brngt. ;
Calami ten, three species; Sigillaria, one species; Lepidodendra, none. Neuro¬
pteris Moorii Lsqx. begins here, and has some resemblance to an Oolitic species.*
* See, for further detail, Lesquereux's Memoir, Am. Jour. Sci. [2] xxx. p. 367.
CARBONIFEROUS PERIOD.
348
2. Animals.
The animal life of the Coal measures is either (1) of land or fresh¬
water origin ; (2) of brackish-water origin ; or (3) of marine origin ;
and this is the first of the ages in which this distinction has been
proved by actual discovery to have existed, although probably a
fact in at least the latter half of the Devonian. Most of the lime¬
stones and some of the sandstones and shales contain marine fos¬
sils; while, on the contrary, other' deposits of sand and clay bear
evidence that they are not of the sea, any more than is the vegeta¬
tion which covered the lands.
The species include, among Protozoans, the little Fusnlina of the
Rliizopod group, a shell consisting within of minute cells, and
related to the Nummulites of a later period. (See fig. 193, p. 164.)
Among Radiates, Corals and Crinoids, both Palaeozoic in type.
Among Mollusks, numerous Brachiopods, Spirifers and Producti
being especially abundant; Conchifers; Gasteropods, the species
for the most part without beaks to the shells ; Ceplialopods of the
genera Nautilus, Goniatites, and Orthoceras. A Palaeozoic cast is appa¬
rent throughout.
But, while thus Palaeozoic in marine life, there is a new terrestrial
feature in the appearance of land-snails of the modern genus Pupa,
belonging to the highest group of Gasteropods, the Pulmonates.
Among Articulates, there is, in nearly all of the departments, a
rise above the peculiarly Palaeozoic grade, for Trilobites are rare;
and—what is of still more progressive aspect—there are Insects and
also Myriapods (Centipedes).
Among Vertebrates, the fishes are all of Palaeozoic cast. They
coipprise only Ganoids and Selachians. The Ganoids have vertebrate
tails, and the Selachians belong to the two extinct tribes of Cestra-
cionts and Hybodonts,—the latter commencing with the Carbonife¬
rous age.
But there are also Reptiles, air-breathing Vertebrates ; and these
are new types, prophetic of the Reptilian age, which was next to
follow. These early Reptiles* are (1) Amphibians, allied to the frog
* The following are the general characteristics of Reptiles and of their sub¬
divisions :—
Reptiles are cold-blooded animals, like Fishes, but air-breathing, like birds
and quadrupeds. They are of low vital activity, with the temperature variable
and in general directly related to that of the surrounding medium. The verte¬
bras differ from those of mammals in being convex and concave at the opposite
ends, and in a few cases concave at both extremities, approximating, in this last
344
PALAEOZOIC TIME—CARBONIFEROUS AGE.
and Salamander, and in part, if not altogether, of the tribe of Laby-
rinlhodonts, having the body covered with scales; (2) Lacertians, or
inferior species of the Lizard tribe ; (3) Swimming Saurians (Enalio-
saurs, or sea-saurians, as the word signifies), allied to the Ichthyosaurs
ease, to those of fishes. The teeth, when set in sockets, never have more than
one prong of insertion, while those of Mammals may have two or more. They
are of two types, which are so fundamentally distinct that they require the
division of the class into two sub-classes.
I. Amphibians.—Breathing when young (or in the tadpole state) by means of
gills, and, with a few exceptions, undergoing a metamorphosis in which they
become gill-less. Heart with three cavities.
II. True Reptiles.—Having no gills at any period of life, and undergoing
no metamorphosis. Heart with three or four cavities.
I. Amphibians (Batrachians of most authors).
The Amphibians are the inferior type, and by some zoologists they are re¬
garded as an independent class, intermediate between Reptiles and Fishes. The
skeleton is distinguished by having (1) two occipital condyles for the articula¬
tion of the head with the body, one placed either side of the foramen ; (2) the
ribs very short, or rudimentary, or wanting; (3) the skull flat and usually broad,
and of a loose and open structure. The body in living species is covered with a
soft skin, with sometimes minute scales, as in the Coecilians. In an extinct
grohp there are distinct scales; and these species in this and other ways approach
the true Reptiles.
There are three tribes among living species, and a fourth of extinct species, if
not also a fifth.
1. Ccecilians, or Snake-like Amphibians.—Body having the form of a snake;
no feet. ,
2. Salamandroids, or Batrachia Urodela.—Body usually lizard-like, or re¬
sembling in form a tadpole; having short legs, as in the Salamanders; some¬
times, as in Siren, only the two fore-feet developed ; ribs short. They graduate
downward into species that keep their gills through life, which, while perfect
animals, are representatives of the embryonic or young state of the higher Am¬
phibians. In others of intermediate grade the gill-opening is retained, but not
the gills. But in the large majority the gills and gill-openings both disappear.
Among the Salamandroids,—
Some retain their gills through life, as the Sired>m, or Axolotl, of Mexico and
western North America, Siren and Necturus of the United States, and Proteus
of the Adelsberg Cave, Carniola.
Others retain the gill-openings, but not the gills, as Menopoma of the Alle¬
ghany region. The animals are large, broad, and flat, sometimes over two feet
long. The Amphiuma of the Southern States is another example. The Merjalo-
batrachu8 (or Sieboldia) is closely related, although the gill-openings become
closed up; it is the largest of the existing tailed Amphibians, having a length
exceeding three feet. The fossil Andriats Scheuclizeri is a Tertiary species re¬
lated to it.
CARBONIFEROUS PERIOD.
345
of the Mesozoic. Remains of three or four of the Reptiles were
found at the Joggins in Nova Scotia, in the interior of a Sigillaria
stump, which had become partly hollowed out by decay and after¬
wards filled by sand and mud in the marsh or forest where it stood,
Salamandrids.—Species without gills or gill-openings in the adult state.
In most of the North American Salamandrids there are teeth on the vomer,
and no parotid gland; while the species of Europe want these vomerine teeth,
and have parotid glands.
3. Batrachoids (so named from the Greek (larpaxos, a frog), or Batrachia
Anonra. Body having four long legs (the hinder the longer) and no tail; as
in the toads and frogs. The teeth are small, and mostly on the roof of the
mouth on the vomer, with none in the lower jaw ; the vertebra) are typically
ten, but sometimes coalesce so as to appear fewer, the apparent number seldom
exceeding eight ; the ribs are wanting.
4. Labyrinthodonts.—The species of this group of extinct Amphibians re¬
semble the Batrachoids in having (1) double occipital condyles; (2) teeth on
the vomer; (3) short, if any, ribs; (4) usually large palatine openings: and
they approach Saurians in having (1) the teeth stout and conical, and set in
sockets; (2) the body covered with plates or scales; (3) the size sometimes very
great. The teeth have the labyrinthine arrangement of the dentine and cement
that characterizes the Sauroid fishes among Ganoids (see fig. 481), and which
is still continued in that group among the living Gars; and hence the name
Lalyrinthodonts.
The Ganocephala are supposed by some to be related to the inferior Sala-
mandroids, while approaching Ganoid fishes in the sculptured bony plates which
covered the head, and in some other characters.—Ex., Archegosaurus and Apateon.
Agassiz considers them, on good grounds, true Ganoids.
II. True Reptiles.
The skeleton in the true Reptiles has (1) but one occipital condyle below the fora¬
men ; (2) a series of ribs ; (3) a covering of scales or plates, with rare exceptions.
The existing species, and part of the extinct, belong to three tribes:—
1. Snakes, or Ophidians.—(1) Body without legs with rare exceptions; (2)
no sternum; (3) eyes without lids; (4) no external ear.
2. Saurians.—Body (1) without a carapax and with a tail; and having (2)
four feet (rarely two, or none); (3) a sternum corresponding to two united verte¬
brae, sometimes more; (4) eyes with lids, or seldom without; (5) usually an ex¬
ternal ear-opening.
3. Turtles, or Chelonians.—Body having (1) a carapax, or shell, made of
several pieces firmly united; (2) a very large sternum forming the under surface
of the body ; (3) a horny beak instead of teeth ; (4) an external car-opening ; (5)
neck and limbs very flexible. The Chelonians have many marks of superior
rank. But the species appear to be analogous to birds among the higher verte¬
brates, or the bats among mammals,—that is, inferior in grade, because they are
of a small type or life-system, such as are styled microsthenic in the remarks on
Mammals. (See under the Triassic period, p. 421.)
346
PALAEOZOIC TIME—CARBONIFEROUS AGE.
before its final burial by the deposits that were increasing around
it; and along with mineral charcoal derived from the wood, and the
bones of the Reptiles, there were also more than fifty shells of the
land-snail Pupa vetusta, and the Myriapod above alluded to, besides
Saurians—The Saurians vary in length from a few inches to fifty or more
feet. In some the teeth are set in sockets,—whence they are called Thecodont
Saurians (from a case, and oSov$, tooth). In others (Pleurodonts) the teeth are
implanted in a groove, the outer border of which projects more than the inner; in
others (Acrodonts) they arc soldered firmly to the salient part of the jaw-bone.
The prominent tribes are as follow, beginning with the highest in rank:—
1. Dinosaurs (beivog, terrible, and cavpog, a lizard).—Reptiles of great size,
all now extinct, having many mammalian characteristics: (1) the long bones
have a medullary cavity; (2) the feet are short, and, with the exception of the
ungual phalanges, like those of' pachyderms ; (3) the sacrum consists of at
least five united vertebrae ; (4) the lower jaw in some species has lateral motion for
trituration. (Pictet.) Include the huge Mcyalosaur, Ilylseosaur, Ljnanodon, etc.
In the sacrum made up of five united vertebrae, and some other characters, these
species approach the mammals, and show their superiority to all other Reptiles.
2. Crocodilians, or Cuircissed Saurians.—Body having (1) a cuirass made of
bony plates; (2) large, conical teeth in sockets in a single row; (3) one jugale;
two premaxillary bones; (4) sacrum formed in general of two vertebrae; (5)
heart with four cavities; external nostrils at the extremity of the snout. The
modern species have concavo-convex vertebra),—that is, the anterior face is con¬
cave and the posterior convex; in others, as the extinct Cetiosaur and Steneu-
saur, they are convexo-concave; and in a third group, including the extinct
Teleosaur, Jlfacrospondylus, etc., they are doubly concave.
3. Lacertians, or Scaly Saurians.—Body having (1) corneous scales ; (2) the
teeth rarely in sockets; (3) no jugale; one ventricle, one premaxillary bone;
(4) sacrum consisting of two vertebra) at the most. The Lizards, Itjuanas, and
Monitors are the types of the tribe.
A few extinct species characterized by small scales are Thecodonts, like the
Crocodiles, so that they stand apart from other Lacertians, and arc intermediate
between them and Crocodilians. Such are the Thecodvntosaur, Palseosaur, and
Proterosaur (fig. 617 A),—among the earliest of true Reptiles, and the pre¬
cursors of the Crocodiles and Dinosaurs.
The Ifosasaur (fig. 792), on the contrary, although of large size (twenty-five
feet long), had the teeth inserted in a groove, as in the modern Lacertians. The
same was the case with the Geosaur ; and both are related to the Monitor of the
Nile ( Varamts Niloticns).
Besides these tribes, there afe two extinct groups :—
4. Enaliosaurs (from ei/a\ios, marine, etc.), or Sioiinminij Saurians.—(1) Fur¬
nished with paddles for swimming; (2) having the vertebrae biconcave,—another
fish-like characteristic; (3) teeth large, and set in a groove. Ichthyosaur and
Plesioecinr are the most common genera. (See figs. 708-713, 715.)
5. Pterosaurs (from a winy, etc.), or Fly iny Saurians.—The most common
genus is Pterodactyl (fig. 739). By the excessive elongation of tlffe little finger of
CARBONIFEROUS PERIOD.
347
fragments of many other specimens of the Pupa, and a few indi¬
viduals of a small Spirorbis, the spiral shell of a worm of the Serpula
tribe. The figure on p. 32G (fig. 5G0) represents a section of tire
part of the Coal measures in which these remains were found: the
stump was twenty-two inches in diameter and nine feet high. The
first discoveries at this place were made by Dawson and Lyell. in
1851. Dawson observes that the shells were probably the food of
the Reptiles, adding that he has found in the stomach of a recent
Menobranchus (M. lateralis) as many as eleven unbroken shells of the
fresh-water snail Physa heterostropha.
Such a congregation of animals in a single stump proves, as Daw¬
son states, that the species of the tribes represented were not rare
in the marshes and forests of Carboniferous Acadia.
A. terrestrial feature thus appears in three out of the four sub-king¬
doms,—the Molluscan, Articulate, and Vertebrate. There are land
and fresh-water shells in the first; Insects and Myriapods (or Centi¬
pedes) in the second ; Amphibians and other Reptiles in the third.
The Radiate sub-kingdom contains no terrestrial species, and hence
did not admit of the same kind of progress.
Characteristic Species.
1. Protozoans.—Rhizupods.—Fusulina cylindrical and F. elongata, resem¬
bling fig. 193, p. 164. The first is a Russian species, and there is some question
whether the American is identical with it. It occurs in vast numbers, almost
making up the limestones in some places, and has been observed in Ohio, Illi¬
nois, Missouri, and Kansas. In the United States the genus Fusulina is confined
to the Coal measures; but in Russia it occurs also in the Subcarboniferous rocks.
2. Radiates.-—(«.) Polyps.—The Coral Cyathaxonia prolifera McCliesney,
from Illinois, (b.) Echinodenns.— Crinoids of the genera Poteriocrinus, Actino-
crinus, etc.; Echinoids of the Palmozoic genus Archxocidaris.
3. Mollusks.—-(a.) BracMopods.—Fig. 591, Spirifer cameratus Morton (S.
3feusebachanun Roemer), from the Lower and Upper Coal measures, and occur¬
ring in Ohio, Kentucky, Illinois, Missouri, Kansas, Texas, New Mexico, and
Utah. This species is closely allied to S. striatus (figs. 211, 212, p. 181), and is
the fore-feet, support was afforded to a membrane which extended to the tail
and made a wing for flying. The remaining fingers were short and furnished
with claws. The long, slender jaws were set with a large number of teeth in a
groove. The bones were hollow and light, as in birds. They had the habits of
bats, and wings of a similar character. But in bats, all the fingers of the hand
but the thumb are elongated for the purpose of the wing, and the thumb alone
is used for clinging.
Chelonians.—The Turtles, or Chelonians, are of two tribes :—
1. The Sea-Turtles,—furnished with paddles instead of feet.
2. The Land-Turtles,—furnished with feet.
348
PALEOZOIC TIME CARBONIFEROUS AGE.
regarded by some as only a variety of it; but it belongs exclusively, in this
country at least, to the Coal measures, and not to the Subcarboniferous in which
the S. striatus is found well marked. Fig. 592, Productus Rogersi Norwood &
Figs. 591-594.
ISRAcnioi'ODS.—Fig. 591, Spirifer cameratus; 592, Productus Rogersi; 593, Chonetes me-
soloba; 594, Atkyris subtilita.
Pratten, from Illinois, Kansas, and New Mexico; fig. 593, Chonetes mesoloba, a
common species ; fig. 594, Athyris (Terebratula) subtilita, very common in the Coal
measures, and not known in the American Subcarboniferous, although reported
from the latter in England. There are, however, Subcarboniferous forms dis¬
tinguishable with difficulty from it. Spirifer Kentuckensis is an Upper Coal-
measure species from Kentucky, Missouri, and near Pecos village, New Mexico.
The following first appeared in the Subcarboniferous, and are continued into
Figs. 595, 596.
Conchifers.—Fig. 595, Area [?] carbonaria; 596, Allorisma subcuneata.
the Carboniferous: Productus punctatus (fig. 545, p. .314), P. Cora, P. muricatus,
P. semireticulatus (fig. 229, p. 183), Spirifer luieatus.
(b.) Conchifers.—Fig. 595, Area [.?] carbonaria Cox, Upper Coal measures of
Kentucky; fig. 596, Allorisma subcuneata, from Kansas. Aviculopecten recti-
CARBONIFEROUS PERIOD.
349
lateraria, from the Upper Coal measures, Kentucky. Pecten \Aviculopecten]
aviculatus Swallow, Kansas; Pinna peracuta Shuin., Missouri, Kansas; Lima [?]
retifera Shum., Kansas; Mytilus [Modiola .?] Shawneensis Shum., Kansas.
(e.) Gasteropoda.—Fig. 598, Bellerophon carbonariua Cox (often referred to
B. Urii), Upper Coal, Kentucky; fig. 597, Pleurotomaria tabulata; fig. 599, P.
spherulata; fig. 600, Macrocheilns? fusiformis ; Murchisonia minima Swallow,
Figs. 597-601.
Gasteropods.—Fig. 597, Pleurotomaria tabulata; 598, Bellerophon carbonarius; 599, Pleu¬
rotomaria spherulata; 600, Macrocheilus ? fusiformis; 601, Dentalium obsoletum.
Missouri; fig. 601, Dentalium obsoletum. Also the Land-snail (Helix family)
Pupa vetusta Dawson (fig. 601 A), half an inch long; from the Coal measures
of the Joggins, Nova Scotia. It is made a new genus, Dendropupa, by Owen.
(d.) Cephalopoda.—Nautilus Missouriensis Shum., Lower Coal measures, N.pla-
nivolvus Shum., Upper C. M.; Goniatites politus Shum., near Middle C. M.; G.
parvus Shum., Upper C. M.; Orthoceras aculeatum Swallow, Upper C. M.; O.
moniliforme Swallow, Upper C. M.,—all from Missouri.
4. Articulates.—(a.) Worms.—-A species of Serpula of the genus Spirorbis,
Coal beds of Nova Scotia.
(6.) Crustaceans.—Trilobites: Phillipsia Missouriensis, P. major, P. Clifton-
ensis,—all described by Shumard,—from the Upper Coal measures of Missouri.
Fig. 601 A. Fig. 602. Fig. 602 A.
Blattina venusta.
Ostracoids: Beyrichia Americana Shumard, from Missouri. Tetradecapods:
species of Amphipods from Illinois, and of Isopods from Nova Scotia.
(c.) Myriapods.—Fig. 602, Xylobius Sigillarice Dawson, from the Coal mea¬
sures of Nova Scotia, and supposed to be related to the modern lulus ; a, organ
(labrum ?) with its palpus, pertaining to the mouth, enlarged. The species must
350 PAL2EOZOIC TIME—CARBONIFEROUS AGE.
have burrowed into the interior of the Sigillaria trunk in which it was found.
(Dawson.)
(d.) Insects.—Fig. 602 A, Blattina venusta Lesquereux, from the Coal measures
at Frog Bayou, Arkansas. The specimen is one of the wings; and it very closely
resembles the corresponding wing of a modern Cockroach (genus Blatta). Re¬
mains of Neuropterous Insects have been found in Illinois. (See p. 761.)
5.Vertebrates.—(a.) Fishes.-—Fig. 608 A, Eurylepis tuberculatus Newberry;
and fig. 608 B, Ccelacanthus elegans Newberry,—both Ganoids from the Coal mea-
Gaxoids.—Fig. COS A, Eurylepis tuberculatus; 603 B, Ccelacanthus elegans.
surcs at Linton, Ohio. The latter is remarkable for not having the tail hetero-
cercal, although strictly vertebrated. The genus Eurylepis of Newberry is a
group of small but highly-ornamented fishes, allied to Palxoniscus, but distin¬
guished by the high side scales. Other Ganoids occur of the genera Megalich-
thys, Palxoniscus, Amblypterus, Pygopterus, Rliizodus, and Ccelacanthus, in the Coal
measures of the United States and Nova Scotia.
Among Selachians the following European genera have been recognized in
the Coal-measure limestones of Pennsylvania, Ohio, Indiana, Illinois, etc.,—the
species being generally distinct from those of the Old World :—1. Cestracionts :
genera Ctenoptychius, Petalodus, Helodus, Cachliodus, Poecilodus, Pleuracanthus,
Ctenacanthus, and Oracanthus. 2. Hybodonts : genera Diploids and Cladudus.
(Newberry.)
(6.) Reptiles.— AnqBiibians.—Fig. 604A, Raniceps Lyellii Wyman, found by
Dr. Newberry along with fossil fishes at Linton, Ohio. According to Wyman,
it has many of the characteristics of the Batrachians (frogs), or tail-less Amphi¬
bians (whence the name, signifying Frog-headed), but appears to bo interme¬
diate between that group and the Salamander tribe (tailed Amphibians). No
scales have been observed: if possessing them, like the species of Nova Scotia,
it would rank among the Labyrinthodonts.
Baplietes plauiceps Owen, is the name of an Amphibian from Pictou, Nova
Scotia. The specimen is a portion of the skull, seven inches broad,—enough to
show the great size of the animal. According to Owen, it was probably a scale-
covered and voracious animal of the Lahyrinthodont tribe.
Dendrerpeton Acadianum is a smaller and narrower reptile from Nova Scotia,
and one of the number found in the stump of a Sigillaria at the Joggins, as
Fig. 603.
CARBONIFEROUS PERIOD.
351
mentioned on p. 345. It was probably about two and a half feet long; the body
was covered with scales, and the whole surface of the cranium was sculptured.
Dawson regards it, therefore, as most nearly related to the Labyrinthodonts.
The name is from the Greek fcvlpov, tree, and eprerov, reptile.
Amphibian footprints have been observed in the Coal measures both of Penn¬
sylvania and Nova Scotia. Near Westmoreland, Pa., in a layer situated about
100 feet below the horizon of the Pittsburg coal, Dr. A. T. King counted twenty-
Fi:r. 604.
Reptiles.—Fig. A, Raniceps Lyellii; b, Vertebrae and ribs of a Lacertian; c, Vertebra of
Eosaurus Acadianus.
three consecutive steps of one individual. Those of the hind-feet are five-toed,
and of the fore-feet four-toed,—the former five and a half inches long, and the
latter four and a half inches. The distance between the successive tracks is
six to eight inches, and between the two lines about the same; which shows
that the animal was large, about as long as broad, and probably a Batrachian
of the Labyrinthodont tribe. The species is called Thenaropus heterodactylus.
Lacertians.—Along with the Raniceps were found some of the ribs and ver¬
tebra of two other species of Reptiles, one specimen of which is represented
352
PALAEOZOIC TIME—CARBONIFEROUS AGE.
in fig. 604 B. The existence of ribs separates them from Batrachians, and their
length from the Salamandrians; and in this characteristic they approximate to
the Lacertians or Lizard tribe among true Reptiles. Dawson has described
three species under the generic name Hylonomus, which were found with the
Dendrerpeton ; they have long ribs, as well as scales, and may have been related
to the above from Ohio. He regards them as probably Lacertian.
Enaliosaurs.—Two vertebrae of a large swimming Saurian have been found
by 0. C. Marsh in the Nova Scotia Coal measures, at the Joggins, about
5000 feet below the top of the series. Fig. 604 C represents one of the ver¬
tebrae, reduced one-half, and a, a transverse section. The resemblance to the
vertebra of an Ichthyosaurus (see fig. 710) is close. From the depth of its
concavities, the animal is supposed to have been one of the most fish-like of the
Bnaliosaurs. But without more of the skeleton it is difficult to pronounce on
its exact relations. The species is named by Marsh Eosaurus Acadianus.
COAL MEASURES OF FOREIGN COUNTRIES.
I. Distribution of Coal Regions.
Coal beds of the Carboniferous age are found in Great Britain,
France, Belgium, Spain, Germany, Hungary, and China. But it is
not yet known that any beds of this age occur in South America,
Africa, Australia, or in the whole of southern, central, and western
Asia, or in either European or Asiatic Russia. Passing up from
Africa and the Orient over Europe, we find the smallest amount
of coal in Germany or southeastern Europe ; the next in order, in
Belgium, France, Spain, Great Britain; or in proportion to the
square miles of surface approximately as follows:—France, l-100th,
Spain, l-50th, Belgium, l-20th, Great Britain, l-10th. The number
of square miles of coal area in these countries is nearly as follows;
that of North America is added for comparison :—
Belgium
France
Spain
Great Britain and Ireland
Square miles.
518
. 2,000?
. 4,000
. 12,000
British Provinces.
United States
18,000
130,000
Total in North America
148,000
The contrast is striking in its bearings on the earth's future, and
has a profound historical interest.
CARBONIFEROUS PERIOD.
353
Excluding America, Great Britain takes the lead of the rest of the
world both in its actual amount of coal and the extent of the coal
area as compared with the whole surface. With an area of 120,290
square miles, there are about 12,000 square miles of coal lands.
British America, however, in the provinces of New Brunswick, Nova
Scotia, Cape Breton, and Newfoundland, stands ahead of her in
both respects, its area of 81,113 square miles containing 15,000 or
18,000 square miles of coal land. The State of Pennsylvania leads
the world, its area of 43,960 square miles embracing 20,000 of coal
land. The Belgian coal fields (a portion of which extends into
France) are the most worked among the European.
Russia has a great area of Subcarhoniferous rocks, containing
some little coal, but only small areas of the Coal measures, in its
southern part.
In England (see the following map, in which the black areas are the Carboni¬
ferous) the coal regions are situated in a band running north-northeast across
from South Wales to the northeast coast, where is the Newcastle basin. The
principal regions are the South AVales, 600,000 square acres in area, and, in the
same latitude, the region about Bristol, east of the Severn ; the small patches in
central England, in AVorcestershire, Shropshire (Coalbrook Dale), AArarwickshire,
Leicestershire, and Staffordshire; north of these, the great Lancashire region,
which borders on Manchester and Liverpool, with the basin of Flintshire on the
Dee, the whole together over 500,000 square acres ; a little to the east, the York¬
shire coal region, about Leeds and Sheffield, 650,000 square acres in area; far¬
ther north, a patch on the western coast in Cumberland, about AArhitehaven, etc.;
and on the eastern coast, the great region of Newcastle, 500,000 square acres in
area.
In Scotland the beds cover an area of about 2000 square miles, and lie
between the Grampian range on the north and the Lammermuirs on the
south.
In Ireland there are several large coal regions,—that of Ulster, estimated at
500,000 square acres, of Connaught, 200,000, of Leinster (Kilkenny), 150,000, of
Munstcr, 1,000,000.
The coal workings are carried on in most of the British mines by a regular
system of mining. The depth of one of the mines of the Newcastle coal field is
1500 feet; of another 1S00; and of those of Yorkshire about 1000 feet. At
AA'hitehaven they reach out far under the sea.
The coal of England, Scotland, and Ireland is mainly bituminous or semi-
bituminous. Anthracite occurs in South AA^ales, especially its western part,
and also in the mines of southern Ireland (Cork, Kerry, Limerick, and Clare); but
this variety is in general less hard and more inflammable than that of Penn¬
sylvania.
The associated rocks are similar to those of America,—viz., conglomerates,
sandstones, shales, limestones, and iron-ore beds; and fire-clays usually under¬
lie each bed. Some deposits are evidently of fresh-water origin, others marine
or of brackish-water.
24
354
FAloSSOZOIC TIME—CARBONIFEROUS AGE.
Fig. 605.
Eig. 605, Geological Map of England. The areas lined horizontally and numbered 1 are
Silurian. Those lined vertically (2), Devonian. Those cross-lined (0), Subcarboniferous.
Carboniferous (4), black. Permian (5). Those lined obliquely from right to left, Triassic (6),
Lias (7 a), Oolite (7 5), Wealden (S), Cretaceous (9). Those lined obliquely from left to
right (10, 11), Tertiary. A is London, B, Liverpool, C, Manchester, D, Newcastle.
The following are the principal coal-mines of the countries of Europe:—
France.—Basin of the Loire (St. Etienne).—Moselle (Saarbriick).—Bur¬
gundy.—Languedoc.—Provence.—Limousin.—Auvergne.—Brittany.
CARBONIFEROUS PERIOD.
355
Belgium.—Liege Coal field,—the eastern division.—Hainault Coal field,—
western division.
Germany.—Basin of the Saar, trihutary to the Moselle on the borders of
France.—Basin of the Ruhr, tributary to the Rhine, near Dusseldorf,—the
eastern extension of the Belgian region. In Saxony, near Zwickau and Dresden.
Austria.—Bohemia, south of the Erzgebirge and Riesengebirge, and reaching
into Silesia.
Spain.—In the Asturias (largest).—Near Cordova.—Catalonia (small).
Portugal.—Near Coimbra.
II. Life.
1. Plants.
The same genera are represented among the European coal beds
as occur in America; and very many of the species are identical.
In this respect the vegetable and animal kingdoms are in strong
contrast; for the species of animals common to the two continents
have always been few.
The following table, by Lesquereux,* shows the number of American species
of the several genera that have also been found in the European Coal measures,
as well as the number peculiar to each, America and Europe:—
Genera of Coal Plants.
Species peculiar
to America.
Species peculiar
to Europe.
Species common
to both.
Noeggerathia Sternb
3
5
1
Cyclopteris Brngt
1
2
2
Neuropteris Brngt
21
16
12
Odontopteris Brngt
6
6
3
Dictyopteris Gutb
1
1
0
Spheriopteris Brngt
20
41
12
Hymenophyllites Giipp
8
10
2
Rhodea Sternb
0
1
0
Trichomanites Gopp
0
4
0
Steffensia Giipp
0
1
0
Beincrtia Giipp
0
1
0
Diplazites Gopp
0
2
0
Woodwardites Giipp
0
2
0
Alethopteris Sternb
12
20
9
Callipteris Brngt
2
1
1
Peeopteris Brngt
16
49
12
Aphlebia Sternb
0
6
1
Caulopteris Brngt
4
4
0
Psaronius Brngt
10
6
0
Crematopteris Schp
1
0
0
* Am. Jour. Sci. [2] xxx. 66. In the table, as originally published by Les-
quereux, the species of Dr. Newberry's cabinet are added with an asterisk : the
above has been modified upon advice received from the latter. The identifica¬
tion of American with European species requires more careful investigation, as
Lesquereux and Newberry both observe.
356
PALiEOZOIC TIME—CARBONIFEROUS AGE.
Genera of Coal Plants.
Species peculiar
Species peculiar
Species common
to America.
to Europe.
to both.
Scolopendrites Lsqx
1
0
0
Whittlesey a Newb
1
0
0
Cordaites Ung
1
0
2
Diplotegium Corda
0
0
1
Stigmaria Brngt
5
2
5
Sigillaria Brngt
21
37
17
Syringodendron Brngt
2
2
2
Diploxylon Corda
0
0
1
Lepidodendron Brngt
14
10
11
Ulodendron Rhode
0
4
2
Megaphytum Artis
2
4
0
Knorria Sternb
2
1
2
Halonia LI. & Ilutt
0
2
1
Lepidophyllum Brngt
7
2
4
Lepidostrobus Brngt
1
1
2
Cardiocarpum Brngt
7
6
2
Trigonocarpum Brngt
6
5
5
Rhabdocarpus Gopp. & Brngt. ..
2
6
1
Carpolithes Sternb
12
52
6
Selaginites Brngt
0
1
0
Lycopodites Brngt
1
12
0
Lepidophloios Sternb
1
0
1
Bothrodendron Gopp
0
1
0
Calamites Suck
2
5
11
Bornia Sternb. & Giipp
1
1
0
Asterophyllites Brngt
5
8
7
Annularia Sternb
1
0
5
Sphenophyllum Brngt
5
3
3
According to this table—which was prepared in 1860—there are in all about
350 known American species, and 490 European (and British); and of these
146 are common to the two continents. In other words, more than one-third of
all the American species were growing also in the Carboniferous forests of the
other continent.
2. Animal's,
The most important additions to the facts already stated, fur¬
nished by the European rocks, are those relating to the class of
Insects and Spiders. We learn that besides Cockroaches, which
also existed in Europe, there were probably Weevils, as well as
other kinds of beetles, species related to the Dragon-fly, and also
Termites and Locusts. The class of Spiders (or Araclinidse) was repre¬
sented by Scorpions and Pseudo-scorpions.
The Vertebrates were similar in type to the American, the fishes
being Ganoids and Selachians, and the Reptiles Labyrinthodonts and
other Amphibians.
A review of the species of Radiates and Mollusks is not necessary here, as the
facts add nothing new in principle to what has been gathered from the Ameri¬
can strata.
CARBONIFEROUS PERIOD.
357
The remains of marine species are not common in the Coal measures of Europe
or of Britain, while those of the American coal fields are almost all marine.
Figs 006—010.
Fig. 606, Gampsonyx fimbriatus; 607, Bellinurus (Limulus) rotundatus (X XA)\ 608, Dictyo-
neura anthracophila; 609, Blattina primaeva; 610, Cyclophthalmus Bucklandi.
Fig. 610 A.
Anthracopalsemon Salteri.
\ A number of American Coal measure species are identical with
N. the Na&carboniferous of the other continent. Thus it is with
\ \ the following: Athyris subtilita, lletzia radians, Spirifer
\ ^ lineatus, S. Urii, Productus lonyispinus, P. scabriculus, P. cos-
W tatus, Fusulina cylindrica.
1. Articulates.—(a.) Crustaceans.—No species of Trilobites are reported
from the foreign Coal measures,—showing, apparently, the complete extinction
358
PALAEOZOIC TIME CARBONIFEROUS AGE.
of this ancient tribe. But there were Crustaceans of new kinds. Fig. 007, Belli~
nurus (Limulus) rotundatus, reduced one-half, a species related apparently to the
Horseshoe (Limulus) of the Atlantic coast. Fig. 600, Gampsonyx fimbriatus
like a shrimp in general form, but belonging to the tribe of Schizopods, that is,
Macrourans having an accessory branch to the legs (from oX'ia>, to divide, and
irovf, foot) ; they are the lowest of Macrourans (p. 153). Fig. 611A represents a
species still more like a shrimp, and it has been called Anthracopalsemon, from
Paleemon, the name of a modern genus of shrimps, and the Greek for coal.
It is from Lanarkshire, Scotland. A. dubins and A. Grossarti are other species
referred to this genus, the former from Coalbrook Dale (includes the Ghyphea?
dubia Salter, and Apxts dubinn M. Edwards), and the latter from Lanarkshire:
but the broad flattened carapax indicates a nearer relation to JEylea and Gala-
thea than to Paleemon. Pyyocephalm Gouperi is the name of a Schizopod from
near Manchester, England.
(b.) Spiders.—Fig. 610, Gyclophthalmus Bucklandi, a scorpion of the Coal
measures of Chomle, in Bohemia. Microlabis is another Carboniferous genus,
of the family of Pseudo-scorpions. These are the first of the class of Spiders in
geological history.
(c.) Insects.—Remains of insects have been found at several localities, and
especially at Saarbriick and Wettin. Fig. 609, a wing of the Blattina primscca
Jordan, or Carboniferous Cockroach, very similar to the American (fig. 602 A);
it is from Saarbriick. Fig. 608, wing of Dictyoneura anthracophila Jordan, a
Neuropterous insect of the Semblis family. Saarbriick has afforded also a
species of Termites, another Neuropterous insect; a locust (Orthopterous) for
which the genus Gryllacrishas been instituted; and a beetle or Coleopter referred
to the new genus Tra.rites. Two weevils (Curculionids) have been reported from
Coalbrook Dale (Shropshire), England; but Heer regards them as Crustaceans,
and not Insects.
Vertebrates.—(a.) Fishes.—The fishes of the Carboniferous age are found
most abundantly in the Subcarboniferous limestones, as these were wholly
of marine origin: still, a considerable number of species occur in the Coal
measures. The Selachians .are of the genera Ctenodus, Ctcnoptycliius, Gyia-
canthus, etc., and also Helodns, Gladodus, Orodus, Gtenacanthus, etc., which are
mostly Subcarboniferous. The most common Coal measure genera of Ganoids
are Pcdseoniscus, Amblyptei'us, and Iloloptycliius. All the Ganoids have verte-
brated tails.
(b.) Beptiles.—A few Reptilian remains have been observed in Europe and
Britain similar in general character to those of America, and indicating the
existence of ordinary Amphibians and Labyrinthodonts. One species, Para-
batrachus Golei Owen, is a Labyrinthodont from the British Coal measures.
The Arehetjosaurus Declieni Goldfuss, a Carboniferous species from Saarbriick,
has been regarded as a Proteoid Salamandrian. But Agassiz has observed that
even in their limbs—their most Reptilian feature—they are closely like Ganoid
fishes of the genus Polypterus. Apateon pedestris II. v. Meyer, is another spe¬
cies related to the Archegosaurus, if not of the same genus; it is from near
Miinsterappel, on the Bavarian Rhine. Anthracosaurus Russelh Huxley, of the
Lanarkshire coal-field, is a large Labyrinthodont, allied to the Mastodonsaurus.
CARBONIFEROUS PERIOD.
359
General Observations.
1. Origin of Coal.—(1.) Coal derived from Vegetation.—As the coai
beds and accompanying strata abound in the impressions of leaves
and stems, and the coal also consists of vegetable fibres (p. 328), the
vegetable origin of coal is beyond all reasonable doubt.
(2.) Plants of the Coal.—The plants that have contributed most to
the formation of the great beds of vegetable debris which were
afterwards converted into coal, are the Sigillarids, the Catamites,
and the Conifers, with the Lepidodendra for that of the Lower Coal
measures. The Conifers and Lepidodendra probably spread also over
the dry land covering the plains and hills, while the Sigillarids and
Calamites were mainly plants of the great marshes. Along with
these were numerous herbaceous ferns, but rarely tree-ferns: even
the stems of the small ferns are not common in the coal itself,
though abundant in the accompanying shales.
(3.) The plants either land or fresh-water species.—That the plants
were not such as frequent salt marshes, but, on. the contrary, those
of the land or fresh-water marshes, is obvious from (1) the nature
of the plants themselves ; (2) the absence of sea-weeds from among
the species of the coal beds ; (3) the presence of the remains of
insects. It is not possible that some of the beds have originated
from the vegetation of salt marshes and others from that of the
land or fresh-water marshes, because there is a great uniformity in
the plants of the several beds,—showing that all are of one mode
of growth and origin.
(4.) Coal a result of the decomposition of plants.—Mineral coal is
simply the element carbon along with some kinds of bituminous
substances that consist of carbon and hydrogen, and also admixtures,
small or large, of earthy impurities.
Dry vegetable matter consists of about 49 per cent, of carbon,
6.3 of hydrogen, and 44.6 of oxygen. The first, the essential ele¬
ment of the coal, is solid at the ordinary temperature ; the other
two elements are gases. In the decomposition of wood, the gaseous
part escapes, carrying off part of the carbon in combination with it,
and leaves the rest of the carbon as coal, with more or less bitumen,
derived from a union of some carbon and hydrogen. In this decom¬
position, the oxygen may combine (1) with part of the hydrogen to
form water; (2) with part of the carbon to form carbonic acid or
carbonic oxyd; also the hydrogen may combine with the oxygen of
the atmosphere to form water ; or some of it with some of the carbon
to produce carburetted hydrogen gas, or (with or without oxygen)
the bituminous substances. By these means, half or more of the
3(>0 PALAEOZOIC TIME CARBONIFEROUS AGE.
carbon of the wood is lost as- gas, and nearly all the gaseous ingre¬
dients besides. It has been estimated by Bischof that 100 parts
of wood will not make more than 16 parts of anthracite and 25
of bituminous coal.
Bischof states the conditions and changes as follow:—
Ultimate constitution of wood, anthracite, bituminous coal, and
asphaltum,—impurities excluded :—
Wood. Anthracite. Bituminous coal. Asphaltum.
Carbon 49.1 94.04 82.2 81.6
Hydrogen 6.3 1.75 5.5 9.6
Oxygen 44.6 4.21 12.3 8.8
If the escaping gases in decomposition are carbonic acid and carburetted
hydrogen, the loss of each element for anthracite and bituminous coal would be
as follows:—
For Anthracite. \ For Bituminous Coal.
Wood.
Loss.
Coal left.
Coal left, j
Loss.
Coal left.
Coal left in
in p. c. i
per cent.
Carbon
49.1
34.57
14.53
94.04 |
31.0
18.1
82.2
Hydrogen. J
6.3
6.03
0.27
1.75 !
5.1
1.2
5.5
Oxygen.... j
44.6
43.95
0.65
4.21 ;
41.9
2.7
12.3
1
100.0
84.55
15.45
100.00
78.0
22.0
100.0
The loss for the anthracite is 60.79 per cent, of carbonic acid, and 24.12 of
carburetted hydrogen.
If the escaping gases were carbonic acid and hydrogen, the last forming
water with external oxygen, the whole loss in a similar manner would be—for
anthracite 65 per cent., leaving 35 of coal; and for bituminous coal 581 per cent.,
leaving 411 °f coal.
If, again, the part lost is carbonic acid and water, both derived from the ele¬
ments of the wood, the amount of coal left in case of bituminous coal would
be about 541 per cent.
There is, therefore, a loss of three-fourths of the wood in the case
of bituminous coal, and five-sixths in that of anthracite. Besides this
reduction to one-fourth and one-sixth by decomposition, there is a
reduction in bulk by compression ; which if only to one-half would
make the whole reduction of bulk to one-eighth or one-twelfth.
Consequently, it would take eight feet in depth of compact vegetable
debris to make one foot of bituminous coal, and twelve feet to
make one of anthracite. For a bed of pure anthracite 30 feet thick,
like that at Wilkesbarre, the bed of vegetation must have been at
least 360 feet thick, or, allowing for impurities, over 300 feet.
(5.) Impurities of the coal.—The impurities of the coal are in part
derived from the wood. Silica is contained in the exterior part of
CARBONIFEROUS PERIOD. oul
rushes and many other plants; and this would remain in the
coal. Potash is present in all vegetation ; but, as its salts are solu¬
ble, it would mainly disappear in the course of the decomposition.
Traces of sulphur occur in all vegetable matters as well as animal,
whether microscopic or not, which might, therefore, be present in
the accumulating beds ; and this sulphur, by combination with iron,
would have formed pyrites,—a common impurity in coal beds.
Impurities were also introduced as earth or clay. Even the winds
transport dust, and the waters carry detritus. Both of these means
may have contributed to the earthy ingredients of the coal.
Waters may also bring in other ingredients in solution, as oxyd of
iron in combination either with carbonic acid, sulphuric acid, or
some organic acid ; for iron is carried in these ways (mainly the
last) into all marshy or low regions from the hills around, being
derived from the decomposition of pyrites (a sulphuret of iron) and
other iron minerals.
Sulphate of iron would lose its oxygen from contact with decom¬
posing vegetation, and become sulphuret of iron or pyrites; and
this is another source of pyrites. In the change, the oxygen takes
carbon from the coal or decomposing plants, and forms carbonic
acid, which passes off into the air, and leaves only sulphur and
iron, to make sulphuret of iron, or pyrites.
(6.) Coal-making decomposition takes place only under water. — Where
vegetation decomposes in the open air, all the carbon enters into
gaseous combinations, and is lost in the atmosphere, only traces
remaining to give a dark color to the soil. Hence forests may,
with each autumn, drop tons of solid material to the ground, age
after age, and yet little remain behind to indicate the existence
of that vegetation. But where the bed of leaves and other relics
of the plants is covered by water, so that the air is mostly excluded,
the decomposition is less complete,—precisely as when wood is
charred in a half-smothered fire; a part of the carbon remains behind,
and forms coal. These principles are sustained by facts in all parts of
the world. Hence, if a continent were spread equally with vegetation
from the equator to the poles, it would form and preserve beds of vege¬
table debris and fossils only in its marshy regions, or where the relics
had been swept off into the waters and had there become buried.
The peat-beds of the present day much resemble in origin the an¬
cient plant-beds. (See p. 613.)
2. Climate, Atmosphere.—The growth of the Carboniferous
vegetation was dependent, as now, on the climate and the condition
of the atmosphere.
(1.) Temperature of the ocean and air.—In the animal life of the
waters we have a safe criterion for the temperature of the oceans.
362
PALAEOZOIC TIME CARBONIFEROUS AGE.
Among the species there was the large coral Lithostrotion basaliiforme,
common in both Europe and the United States. One such species
is almost sufficient to prove a similar temperature for the ocean
over these three distant regions. This Lithostrotion was found by
Beechey on the northwest Arctic coast, between Point Barrow and
Kotzebue Sound; and with it occurred other corals, and among the
Brachiopods Productus Martini, well known in lower latitudes. The
Arctic was, therefore, at that time a reef-growing sea; and if the
distribution of corals, forming coral-reefs, was limited by the same
temperature then as now, the waters were at no part of the year
below GG° F. Besides the above species, there have bp en identified
in the Arctic, the European species Productus sidcatus, Airy pa, aspera,
A.fallax: these were found on Bathurst and the neighboring
islands, in latitudes 75° and 77°.
The small diversity in the oceanic temperature of the globe is fur¬
ther shown by the occurrence of the following Carboniferous species
in the Bolivian Andes :—Productus semireticulatus, P. longispinus Sow.,
Athyris subtilita Hall, and a Bcllcrophon resembling B. TJrii Fleming.
The coal beds of the Arctic are evidence of a profuse growth of
vegetation over an extended area and protracted through a long
period. The conditions between the latitudes 70° and 78° were,
therefore, analogous to those over the United States from Pennsyl¬
vania to Alabama and from Illinois to Texas. While a general re¬
semblance to the ancient flora of the United States and Europe is
apparent from the observations which have been made, particular
species have not yet been identified. The plants were not mosses
of peat swamps, such as now extend far north. If we draw any
conclusion from the facts, it must be that the temperature of the
Arctic differed but little from that of Europe and America. Through
the whole hemisphere—and, we may say, world—there was a genial
atmosphere for one uniform type of vegetation, and there were
genial waters for Corals and Brachiopods.
(2.) Moisture of the atmosphere.—A warm state of the globe would
necessarily imply a very much larger amount of evaporation than
now. The climate would be insular throughout, and heavy mists
would rest over the land, making the air and land moist. The
comparatively small diversity of climate between the equator and
poles would probably be attended with fewer storms than now,
and a less rapid movement in the general circulation.
(3.) Impurity of the atmosphere.—In the present era, the atmosphere
consists essentially of oxygen and nitrogen, in the proportion of
23 to 77 parts by volume. Along with these constituents there are
about 4 parts by volume of carbonic acid in 10,000 parts of air. More
CARBONIFEROUS PERIOD.
363
carbonic acid would be injurious to animal life. To vegetable life,
on the contrary, it would be, within certain limits, promotive of
growth ; for plants live mainly by means of the carbonic acid they
receive through their leaves. The carbon they contain comes
principally from the air.
This being so, it follows, as has been well argued, that the carbon
which is now coal, and was once in plants of different kinds, has
come from the atmosphere, and therefore the atmosphere now
contains less carbonic acid than it did at the beginning of the Car¬
boniferous, by the amount stowed away in the coal of the globe.
Such an atmosphere, containing an excess of carbonic acid as well
as of moisture, would have greater density than the present: conse¬
quently, it would (1) have increased heat at the earth's surface, and
this would be the cause of a higher temperature over the globe
than the present. (E. B. Hunt.) This density would (2) tend to
diminish the rate of movement in the atmospheric circulation,
and the frequency of storms or violent disturbances.
During the progress of the Carboniferous period, there was, then,
(1) a using up and storing away of the carbon of the superfluous
carbonic acid, and. thereby, (2) a more or less perfect purification
of the atmosphere and diminution of its density. In earlier time
there had been no aerial animal life on the earth; and as late
as the Carboniferous period there were only reptiles, insects, and
pulmonale mollusks. The cold-blooded reptiles, of low order of
vital activity, correspond with these conditions of the atmosphere.
The after-ages show an increasing elevation of grade and variety
in the living species of the land.
(4.) Influence of the climate on the growth of plants.—A moist warm
climate produces exuberant growth in plants that are fitted for it.
The plants of the Coal period were made for the period. The Sigil-
larice and Calamites manifest, by their characters and mode of occur¬
rence, that they could flourish only in a moist region ; arid the
ferns of the tropics, as well as Equiseta everywhere else, like moist
woods. The Le.pvdode.ndra, by their association with the Sigillarice and
Ferns, show that the same conditions (as is now the case with their
kin the Lycopodia) favored their development. In fact, Lycopodia,
Equiseta, and most ferns, are plants that like shady as well as
moist places. Adding, then, the prevalent moisture and warmth
to the excess of carbonic acid in the atmosphere, we should be
warranted in concluding that, even if there was less sunshine than
at the present time, vegetable growtli must have been more exube¬
rant than now, especially in our colder temperate zones. This
exuberance would not have shown itself in thick rings of growth
364
PALAEOZOIC TIME CARBONIFEROUS ACE.
in trees, made for those very conditions, but, as through the exist¬
ing tropics, under a moist climate, in the great denseness of the
jungles and forests, many plants starting up where but one would
have flourished under less favorable circumstances. Our peat
swamps are often referred to as a measure for the growth of plants
in the Coal era. But this is an assumption not based on a due
consideration of the facts. The peat plants of the present day are
species of the temperate zone alone, and are too different in kind
to warrant a comparison.
3. General Geography of North America.—The Subcarbonife-
rous period was a time mainly of submerged continents; the Car¬
boniferous, of general emergence. The conglomerate (Millstone grit),
with whose formation the Coal period began, marks the transition
from the marine to the land period.
(1.) Epoch of the Millstone grit.—The areas overgrown by Crinoids
became in the Millstone epoch covered to a great extent by pfebbles
and sand. These coarse beds indicate strong currents or heavy
breakers; and such would sweep the surface during an epoch of
slow emergence. The great thickness and coarseness of the beds
through Pennsylvania, along the Appalachian region, point out
that this was the border reef of the continent and the region
of great subsidences. The more sandy character of the beds of
this border in Virginia harmonizes with the general fact in earlier
time ; and so also do the little thickness and finer character of the
beds of Ohio and eastern Kentucky,—a region on the inner margin
only of the subsiding Appalachian area, not participating in the
great change of level.
The coal beds, in this epoch of the Millstone grit, also show that
the continent was in this semi-emerged condition ; for every such
bed is proof that areas of land were here and there above the
ocean, where plants could grow.
(2.) Epoch of the Coal Measures.—As the plants were land-plants,
and the beds cover a vast area stretching almost continuously from
the middle or eastern border of the Appalachian region to the far¬
ther limits of Missouri and Kansas, this great continental region is
safely regarded as at times beyond the reach of the ocean. The
emergence, going on in the Millstone-grit epoch by slow steps of
progress, ended, therefore, in a great increase of the continental
lands. They not only extended from the remote Arctic down to
southern New York, but they spread west and south,—west beyond
Missouri, and south over Tennessee and part of Alabama. Farther
west, there were limestones of the Coal Measure epoch forming,
instead of coal; and these indicate that the old interior sea still
CARBONIFEROUS PERIOD.
365
covered the slopes and summits of the Rocky Mountains, and over
these meridians the waters may have connected with the Arctic
Ocean. The limestones of Point Barrow, at the farther extremity
of the Rocky Mountain range, may be of the same age.
As single coal beds in the earlier part of the series appear to
have had a very wide range, it is safe to conclude that the great
central coal area stood nearly at a common level,—that the region
was a vast plain, with, at the most, only gentle undulations in the
surface breaking its continuity, and with the higher land mainly
over the Azoic and Silurian lands to the north. There were no
Appalachians, for this very region was a part of the great coal-
making plain; there were no Rocky Mountains, for these, as the
Carboniferous limestones prove, were mainly under the sea.
Being thus level, there could have been no great Mississippis, and
no sufficient drainage for the continent; and the wide plains would
have necessarily been marshy, and spotted with shallow lakes.
Eastward there was another similar level area, in Rhode Island
and eastern Massachusetts, which probably extended northeast¬
ward over the Nova Scotia Coal field to the interior of New¬
foundland, covering more or less of Massachusetts Bay, eastern
Maine, Nova Scotia, New Brunswick, and the Gulf of St. Lawrence.
The continent in that direction, therefore, had for the time its
present enlarged limits, and probably spread even beyond. Near
the present mouth of the St. Lawrence must have emptied the prin¬
cipal river of the continent: for in the back country at that era
there were mountains of moderate elevation, to pour waters into
such a stream,—the Azoic heights of northern New York and Canada.
Over these marshes, then, grew the clumsy Sigillarice and Catamites,
and the more graceful Lepidodendra and Conifers, with an under¬
growth of ferns, and upon the dry slopes near by, forests of Lepido¬
dendra and Confers; and the luxuriant growth was prolonged until
the creeping centuries had piled up vegetable debris enough for a
coal bed. Trees and shrubs were expanding, and shedding their
leaves and fruit, and dying, making the accumulation of vegetable
remains. Islands of vegetation, like those now occurring in India,
may have floated over the lakes and contributed to the vegetable
debris. Stumps stood and decayed in the swamps, while the debris
of the growing vegetation, or detritus borne by the waters, accu¬
mulated around them, and their hollow interiors received sands,
or leaves, or bones, or became the haunts of reptiles, as was their
chance.
Where the floating islands and other vegetation were drifted out
into salt-water bays, the coal-bed accumulations might contain
866
PALAEOZOIC TIME—CARBONIFEROUS AGE.
marine shells,—a fact observed in more than one case in the coal
of the United States.
As already explained, there is no reason to suppose that the vege¬
tation was confined to the lower lands: it probably spread over the
whole continent, to its most northern limits. It formed coal only
where there were marshes, or the deposits of vegetable debris be¬
came covered by water-deposits of sand, clay, or other rock-material.
4. Phases in the progressing Carboniferous period.—The con¬
dition of the continent which has been described represents only
one phase in the Carboniferous period. The rocks register a suc¬
cession of changes; for coal beds are succeeded by sandstones, or
shales, or limestones, or iron-ore beds, and many alternations of these
beds, to a thickness fifty times as great as that of the coal beds.
These intervening strata, moreover, may be fresh-water or marine:
in the one case, with fresh-water shells or other inland species ; in
the other, full of Crinoids and Brachiopods, the life of the sea. The
great extent of the continent, wherever these strata occur, under¬
went, therefore, continued oscillations of level, or the sea as un¬
ceasing changes of water-level. After a period of verdure there
followed a desolation as complete as that when the lower Millstone
grit was spread over the surface,—either a subsidence of the interior,
or some other change that led to a general submergence beneath
fresh waters, or a movement or removal or sinking of barriers,
that placed the whole beneath salt water: in either case, the former
vegetation gave way to the water-life again, and the broken relics are
often packed together in the first deposits that ensued. The oscil¬
lations must have been exceedingly various to have produced all
the alternations of shales, sandstones, limestones, and ore-beds.
They must have been also slow in progress: motion by the few
inches a century accords best with the facts. The continent may
have rested long near the water's surface, just swept by the waves.
It may have been long a region of barren marshes; and in this
condition it might have received its iron-ore deposits, as now marshes
become occupied by bog-ores. It must have been long in somewhat
deeper waters, and covered with a luxuriance of marine life.
Finally, the land escaped again from the waters, and the old vege¬
tation spread rapidly across the great flats, commencing a new era
of coal-making vegetable debris; or the escape was only partial,
and coal-plants took possession of one part and made limited coal
deposits, while the sea still held the rest beneath it; for uniform
oscillations of level in all cases through so great an area are not
probable, and therefore the former continuity of a single coal bed
through the East and West requires strong proof to be admitted.
CARBONIFEROUS PERIOD.
367
Should a'general submergence be proved, it remains a question
whether the lowering of the searlevel on the land was due to a
rising of the land, or a deepening of the ocean's bed causing a with¬
drawal of the waters; for the ocean's bed has ever been as liable to
oscillations as the continental part of the crust, and the effects
should have been as much greater than those from the oscillating
land as the area of the ocean is greater. Whichever be the mode,
the movements would generally have been such as would become
appreciable only by the lapse of many years or a century.
In Nova Scotia these changes went on until 14,570 feet of deposits
were formed; and in that space, as has been stated, there are 76
coal seams and dirt-beds, indicating as many levels of verdant
fields between the others when the waters prevailed. In Pennsyl¬
vania there are nearly 3000 feet of rocks in the series, and 60 to
120 feet of coal.
The coal beds are thin, compared with the associated rocks. But
the time of their accumulation, or the length of all the periods of
verdure together, may have far exceeded the time that was given
up to the accumulation of sands and limestones. If there were
but 100 feet of coal in all, it would correspond to between 500 and
1000 feet in depth of vegetable debris. The sands and clays came
in after each time of verdure to store away the product for a future
age.
In the Xova Scotia Coal measures there is evidence in -the fossils
that the waters in which were accumulated the rocky layers that
intervene between the coal beds were, to a large extent, fresh or
brackish. The occurrence of a iS'pirorbis along with the Pupa and
Reptilian remains in the Sigillaria stump has been considered as
evidence in this particular case of the presence of brackish water
during the burial of the stump. There are but few beds in the
whole thickness of the Nova Scotia Coal formation that contain
marine fossils. The land-snail (Pupa) occurs in another bed—an
under-clay—over 1200 feet below the level of the stump in which it
was first found; and in this interval there are twenty-one coal seams,
showing, as Dawson observes, that the species existed during the
growth and burial of at least twenty forests. It proves the terres¬
trial character of the coal vegetation.
In the Interior Continental region, the submergence attending the
formation of these intervening rocks was mostly or wholly marine ;
for all the fossils thus far observed are those of marine species,
and they occur in many strata of limestone, sandstone, and shale
throughout the Coal measures. Over the great Mammoth bed of
Wilkesbarre there are shales (at the township of Hanover) con-
368
PALAEOZOIC TIME—CARBONIFEROUS AGE.
taining marine shells. The thinner shales among the coal beds and
limited arenaceous layers may, however, have been formed when
the marshes became flooded with fresh waters; while the great
sandstones and limestones and thicker shales are all evidence that
the former fresh-water marsh was followed, through submergence,
by a flood of marine waters. The extermination of the Lepido-
dendra of the Lower Coal measures was probably connected with
such a submergence.
The Lower Coal measures extend to the most eastern limits of
the anthracite in Pennsylvania, and contain but little limestone
either in the east or west. The Upper, above the Pittsburg bed,
reach east only over the western portion of that State. This more
western limit shows plainly a rising of the country more to the
east to a height that was too dry for the marsh-vegetation of which
coal was made. We observe, further, that limestones are common
in the Upper Coal measures, and they increase much going west¬
ward ; and finally, as has been stated, they prevail extensively over
the larger part of the Rocky Mountain region.
The coal bed itself bears evidences of alternations of condition in its own
lamination, or even in the alternations in its shades of color. A layer an eighth
of an inch thick corresponds to an inch at least of the accumulating vegetable
remains; and hence the regularity and delicacy of the structure are not surprising.
Alternations are a consequence of (1) the periodicity in the growth of plants and
the shedding of leaves; (2) the periodicity of the seasons, the alternations of
the season of floods with the season of low waters or comparative dryness; (3)
the occurrence, at intervals of several years, of excessive floods. Floods may
bring in more or less detritus, besides influencing the fall and distribution of the
vegetation. In some conditions, there would be a long steeping of the vege¬
tation in the waters before it was put under the pressure of beds of clay or
sand; and the precise quality of the coal would be varied thereby, the decom¬
position of the vegetation depending on the amount of water, the composition
of that water, and the length of time exposed. Newberry has suggested that bitu¬
minous coal has taken the form of Cannel when the vegetation was reduced to
a perfect pulp at the time of the change to coal.
Conclusion.—The Coal period was, then, a time of unceasing change,
—eras of universal verdure alternating with others of wide-spread
and destructive waters, destructive of all the vegetation and land-
life except that which covered regions beyond the Coal-measure
limits. According to the reading of the records, it was a time of
great forests and jungles, and of magnificent foliage, but of few or
inconspicuous flowers ; of Acrogens and Grymnosperms, with no An-
giosperms; of marsh-loving insects, Myriapods and Scorpions as well
as Crustaceans and Worms, representatives of all the classes of Ar¬
ticulates, but not the higher insects that live among flowers ; of the
PERMIAN PERIOD.
369
last of the Trilobites, and the passing climax of the Brachiopods
and Crinoids; of Ganoids and Sharks, but no Teliosts or Osseous
Fishes, that make up the greater part of the modern tribes ; of
Amphibians and some inferior species of True Reptiles, but no
Birds or Mammals ; and therefore there was no music in the groves,
save, perhaps, that of insect life and the croaking Batrachian.
Thus far had the world progressed by the close of the Carboniferous
period.
The special history of the Coal period of Europe and Britain
might be followed out, as has been done for North America. But
it would illustrate no new principles, and would be more appro¬
priate in a general treatise than in a text-book. More facts are to
be ascertained, before the details of the history are as clearly de¬
ciphered.
3. PERMIAN PERIOD (15).
The Permian period, the closing era of the Carboniferous age,
was a time of decline for Palaeozoic life, and of transition towards
a new phase in geological history.
The term Permian was given by Murchison, De Verneuil, and Keyser-
ling, after the ancient kingdom of Permia, in Russia, which included
the existing governments of Perm,Yiatka, Kazan, Orenberg, etc.,
and is covered by the formation. No division of the Permian pe¬
riod in America into epochs has been recognized.
1. AMERICAN.
I. Rocks : kinds and distribution.
The Permian rocks are confined to the Interior Continental basin,
and occur in the portion of it west of the Mississippi,—especially
in Kansas, and some parts of the eastern slope of the Rocky Moun¬
tains. They overlie conformably the Carboniferous ; and, as the
rocks make one continuous series, it is difficult to determine the
limit between the two formations.
In Nebraska and Kansas, they outcrop along the western border of the Carboni¬
ferous region, in a strip running from Nebraska City southward (or a little west-
of-scuth), and also in patches to the east of this range. On the map, p. 133,
the Permian is distinguished by light dots on a dark ground. The beds occur
also about the Black Ilills (near lat. 44° N. and long. 104° W.), on the eastern
slope of the Big Horn Mountains, and, according to Shumard, in the Guadalupe
Mountains in New Mexico.
The rocks are limestones, sandstones, red, greenish, and gray
marls or shales, gypsum beds, and conglomerates, among which the
limestones in some regions predominate.
25
370
PALAEOZOIC TIME—CARBONIFEROUS AGE.
The whole thickness made out by Swallow & Hawn is about 820 feet, and
of this 263 feet are called the Upper Permian, and the rest the Lower. Meek
& Hayden refer the Lower division, with good reason, and also a part of the
Upper, to the Upper Coal measures. The limestones are usually impure, and
also magnesian, like most of the limestones of the same region of older date.
They are generally rather soft or irregular in structure, and much interlami-
nated with clayey or arenaceous beds; some of the layers contain hornstone.
II. Life.
Nothing is yet known respecting the American Permian flora.
Allowing the Permian the widest range attributed to it, the ani¬
mal species are rather numerous; but they include many Carboni¬
ferous forms, and among them Crinoids, an Archccocidaris, and a
Trilobite of the genus Phillipsia, besides Mollusks. But, restricting
the period only to the upper strata, which are recognized by all
investigators as Permian, there are only a few Mollusks.
The species here figured oceur in the uppermost beds (Permian of Meek &
Hayden). Fig. 611, Monotix Hawni M. & II., cast of the outside of the left
valve; 611 a, cast of the interior of the right valve of the same. The genus
Monotis is related to Avicula : it has an opening below the beak for the passage
of the byssus, as shown in the figure. Fig. 612, Myalina perattenuata M. & H.;
fig. 613, BaJcewellia parva ; fig. 614, Pleurophorus subcuneatua M. & H.; fig. 615,
shell of a small undetermined Gasteropod.
Mollusks.—Figs. 611, 611 a, Monotis Hawni; 612, Myalina perattenuata; 613, Bakewellia
parva; 614, Pleurophorus subcuneatus; 615, an undetermined Gasteropod.
Among the species of Mollusks from the beds referred to the Permian by Swal¬
low, 75 in number, one-fifth occur also in the Carboniferous beds below. These
Carboniferous species are mainly those of wide range, as shown in the following
catalogue:—
PERMIAN PERIOD.
371
Streptorhynchus Umbraculum (fig. 550). Chonetes Flemingii N. & P.
" Missouriensis Swallow. Rhynchonella Osagensis, Swall.
Spirifer cameratus (fig. 591). Athyris subtilita Hall.
" planoconvexus Shumard (=S. Urii ?) Mytilus rectus Shumard.
" pectiniferus ? Sow. Myalina subquadrata Sbumard.
Productus semiretieulatus (fig. 229) Martin. " Kansasensis Shumard.
" Rogersi (fig. 592) 4N. & P. Allorisma Minnehaha Swall.
" sequicostatus Shumard. Natieopsis Pricei Shumard.
The species Monotis Haiti Swallow, and two or three others, occur in both
his Upper and Lower Permian. M. Hawni M. & H., M. concava, Bakewellia
antiqua, Solen (?) Permianus, Schizodus Rossicus, Murchisonia subangulata ?,
Nautilus Permianus, Orthoceras Kickapooense, Cyrtoceras dorsatum, are found
only in the Upper.
III. General Observations.
The several points west of the Mississippi at which the Permian
rocks have been found, prove at least their wide distribution over
the Rocky Mountain slopes, although now to a great extent covered
by strata of later date,—the Triassic, Jurassic, Cretaceous, and Ter¬
tiary. We observe the following facts connected with the period: (1.)
The beds are apparently all marine strata, for the fossils are marine.
(2.) The numerous alternations between impure limestones and clays
and some sand deposits indicate oscillations through the period in the
depth of water between moderate depths and very shallow waters.
(3.) The absence of coal beds is proof of no fresh-water Carboni¬
ferous marshes in the regions where the rocks have thus far been
examined. (4.) The non-occurrence of these marine strata over the
region east of the Mississippi (with perhaps a single exception near
the river in Illinois) seems to show that this eastern part of the
continent was dry land. Early in the Carboniferous period, the
Pennsylvania region was raised and became dry even of its old
marshes, for only the Lower Coal measures occur there ; and in the
Permian period, as it appears, the dry region had extended so as
to include all the country east of the Mississippi. (5.) The beds
occur within the same region, or on the borders of the same region,
in which the Coal formation during the Carboniferous period was
represented by limestones ; that is, in the great interior sea which
had so long existed as the Palaeozoic representative of the Gulf of
Mexico,—a comparatively shallow, but extensive, inland sea stretch¬
ing northward. The present western limit of the Gulf is nearly in
a north-and-south line with the western boundary of the State of
«• Kansas.
The existence of these Permian deposits is, then, owing to a con-
372
PALAEOZOIC TIME—CARBONIFEROUS AGE.
tinuation of the conditions that characterized the Carboniferous
period. That era, limestone-making over these western regions,
was prolonged into another when the limestones formed still, but
with numerous interruptions by clay-depositions; and these alter¬
nations were perhaps due to an increasing frequency in the oscilla¬
tions and shallowness of the waters.
The beds are continuous with the Carboniferous, without inter¬
ruption or unconformability, and yet are true Permian, because they
belong to the Permian period in geological time,—a fact indicated
by the identity of genera, and the close analogy of the species of
fossils with the Permian of Europe.
2. FOREIGN PERMIAN.
I. Rocks: kinds and distribution.
The Permian strata of England occur in view along the borders
of the several coal regions, excepting that of South Wales. They
occupy a small area in Ireland about the Lough of Belfast. They
consist of red sandstone and marls overlaid by magnesian limestone.
In Europe the Permian beds in like manner border directly upon
the Coal measures, and the rocks are similar in general character
to those of England.
The Permian beds, before their relations were correctly made
out, were included, along with part of the Triassic, under the
name " New Red Sandstone," and also the " Poikilitic group."
They occur in central Germany from southern Saxony along the Erz Moun¬
tains, over the small German States, west to Hesse Cassel and north to the Hartz
Mountains and Hanover, adjoining. Within this area Mansfeld is one noted
locality, situated in Prussian Saxony, not far from Eisleben; another is on the
southwest borders of the Thuringian forest (Thiiringerwald), in Saxe-Gotha, a
line which is continued on to the northwest by Eisenach towards Miinden in
southern Germany.
In Russia the Permian formation, according to Murchison, covers a region
twice the size of France, extending over the districts that lie along the west side
of the Urals,—Vologda, Perm, and Orenburg,—and others more to the west, and
thus including the country between the Volga and the Urals.
In Thuringia and Saxony the subdivisions of the rocks are (1) the red beds
(or rothe Todt-liegende, lied dead layers,—a sandstone so called because the beds
are red and contain no copper), overlaid by the copper slates (Kupferschiefer,—
a clay-slate worked for its copper at Mansfeld). 2. The magnesian limestone,
consisting of (a) Lower Zechstein, a gray, earthy limestone; (b) Upper Zechstein;
(c) llauchwaclce, a shale partly calcareous and concretionary; (d) Stinhstein,
an impure, fetid limestone. The limestone in England has four divisions:
PERMIAN PERIOD.
373
(a) compact; (b) fossiliferous*; (c) brecciated; and (d) crystalline and other
limestones.
In Russia there are magnesian limestones interlaminated with sandstones,
and marls of various colors, with some gypsum, and an occasional thin seam of
coal.
The coincidence is worth noting that the Permian rocks of Russia or interior
Europe lie between its great river the Volga and the summit of the Ural Moun¬
tains, just as in interior North America they occur between its great river the
Mississippi and the Rocky Mountain summits. It may be that on both conti¬
nents the region between the great river and the ocean had been raised above
the sea during the preceding changes.
II. Life.
1. Plants.
The Permian plants are closely related to those of the Upper
Coal measures. They are mostly of the same genera, and in part
of the same species. There are Calamites and Equiseta, many ferns,
including tree-ferns, and a number of Conifers : yet the prevalence
of some new kinds gives a somewhat different aspect to the flora.
Among the trees those of the genus Walchia (fig. 616 C) are most
characteristic.
The Ferns are of the genera Neuropteris, Sphenopteris, Peccpteris, etc., and
there are also species of Asterophyllitea and Annularia, as well as Catamites,
Fig. 616.
Figs. 616 A, A', Neuropteris Loschii; 616 B, B', Annularia carinata; 616 C, Walchia pini-
formis.
Coal Measure genera. On the other hand, there are no Sigillarise. The Conifers
are more varied: they include Araucarites (Dadoxylon), Pinites, Walchia, etc.
874 PALAEOZOIC TIME CARBONIFEROUS AGE.
The genus Walchia, characterized by lax and Very short, spreading leaves
began near the close of the Carboniferous period, but is much more numerous in
species during the Permian. Tree-ferns of the genus Psaronius are common, as
in the Upper Coal measures.
Fig. 616 A, pinnule or branchlet of a large frond of Neuropteris Loschii, a
species common also in the Coal measures; A', a portion showing the venation.
Fig. 616 B, a small part of a specimen of Annularia carinata Sternberg; the stem
is jointed, as in the Equiseta, and gives off branchlets at the articulations;
these branchlets are also jointed, and have whorls of leaf-like appendages at the
articulations; in 616 B, only the first joint and its whorl are shown, of natural
size; in B' a branch is shown (of reduced size), consisting of its several joints
and whorls, but the natural termination is wanting. Fig. 616 C, Walchia piri¬
formis Sternberg. The figures are from the work of Geinitz and Gutbier on
the Permian of Saxony.
2. Animals.
Corals of the Cyathopkyllum family, Brachiopods of the genera
Productus, Spirifer, and Orthis, Cephalopods of the genera Conularia
and Orthoceras, and Ganoid fishes, with vertebrated or hetero-
cercal tails, give a Palaeozoic character to the Fauna. But there are
many new features : among these the most prominent is the ap¬
pearance of Lacertian Reptiles of the tribe of Thecodonts,—species
having the teeth set in sockets, as the name (from the Greek) implies.
This transition-character is apparent also in the number of old
animal as well as vegetable types that here fade out,—for it is the
period of the last of the species of Productus, Orthis, Murchisonia;
the last of the extensive tribe of Cyathophylloid corals, which made
coral reefs far greater than those of modern seas ; nearly the last
of the extreme vertebrate-tailed (heterocercal) Ganoid fishes. These
groups had already dwindled much before the Permian period;
for some prominent Carboniferous genera, as the Goniatites, do not
reach into it. The old or Palaeozoic world was dying out, while
within it new types were coming forth, prophetic of the earth's
brighter future.
Characteristic Species.
1. Radiates.—(«.) Polyps.—Cyathophylloid Corals; also corals of the genus
Stenopora (Cheetetes). (b.) Eehinoderms.—Crinoids of the genus Cyathocrinux,
a Palaeozoic genus; Echinoids of the genus Eocidaris, near the Palaeozoic
Arcliseocidaris.
2. Mollusks.—(a.) Bryozoans.—Fenestella retifo-rmis, found in the Permian
of Russia, England, and Germany, besides a dozen other related species.
(6.) Brachiopods.—Spirifer tindulatus Sowerby, from England, Lower Zech-
stein in Saxony,—some specimens two and a half inches broad; Spirifer crix-
tatus, from the Zechstein, Germany; Productus horridus Sowerby, from England
PERMIAN PERIOD.
375
and Germany, characteristic particularly of the Lower Zechstein, and occurring
also in the Kupferschiefer; Stroplmlosia excavata, England, Germany (the spe¬
cies of the genera Productus and Strophalosia are exceedingly abundant in
individuals); Camarophoria Schlotheimi von Buch, from Russia, Germany, and
England (the genus is related to Terebratula and Pentamerus, and is peculiar
to the Carboniferous and Permian); Camarophoria sujierstes, Russia.
(e.) Conchifer8.—Monotis speluncaria, England, Russia, and Germany in the
Lower Zechstein; Mytilus (Jlodiola) Pallasi, Russia and Germany; Mytilus
squamosus, Russia, England; Avicula Kazanensis, Russia, Germany; Balcewellia
antiqua, England, Russia, Germany ; Axinus dubius Schlotheim, a very common
species in England, Germany, and Russia. (It includes Scliizodus Scldotheimii
Geinitz, Ax. obseurus Sowerby, and other so-called species.) The genus Axiuus
is of the same family with Triyonia, a characteristic genus in the Reptilian
age.
(d.) Gasteropoda are rare in the Permian. There are a few species of Murchi-
sonia and Straparollus, Palaeozoic genera, besides some others.
(e.) .Cephalopoda existed, and among them two or three species of Ortho-
ceraa.
3. Articulates.—No Trilobites are known. Ostracoids are common. The
first of the Tctradecapoda (p. 153) is found in this formation. The only
species known is an Amphipod, Prosoponiscus problematicus, from the Permian
of Durham, England, first described by Schlotheim, but recently explained by
Bates. Decapods of the order of Macrourans appear to have commenced in the
Coal formation. But the first of the Brachyurans is announced from the Per¬
mian by von Schauroth, who names it Hemitrochiscus paradoxus ; Geinitz regards
it as related to the Pinnotheres family, one species of which is the little crab
found in the oyster: length about one-eighth of an inch.
4. Vertebrates.—(a.) Fishes.—Fig. 617, Palcsoniscus Freieslebeni Agassiz,
one-third the natural size. Common in the Kupferschiefer, and also found in the
Coal measures in England at Ardwick. Over forty species of fishes have been
described. The more characteristic genera are Palseoniscus, Platysomus, Acro-
lepis, Pygojjteriis, and Coelacanthus, but they are also all Carboniferous.
(6.) Iieptile8.—Nine or ten species have been described belonging to the tribes
of Labyrinthodonts and Lacertians. Fig. 617 A, Proterosaurus Speneri, regarded
Fig. 617.
Palseoniscus Freieslebeni (X/fi)-
376 PALAEOZOIC TIME—CARBONIFEROUS AGE.
as a Thecodont Lacertian. It was three and a half feet long, and is from the
copper-slate (Kupferschiefer) of Germany and Saxony. Palseoeaur and Theco-
dontosaur are the names of other Permian genera of Thecodonts.
Fig. 617 A.
Proterosaurus Speneri.
The Permian Thecodont Reptiles are related in many
points to the lizards and monitors (see p. 346), yet have
biconcave vertebrm like the inferior swimming reptiles,
united to the socket-teeth of the Crocodiles. The teeth
are flattened and crenulate at the margins. The fingers in
the Proterosaurus call to mind those of the Pterodactyl, as
Gutbier suggests. The name Proterosaurus is from -rrponpos,
first, and o-avpo;, lizard, or saurian, and Palmosaurus from
jraXaioj, ancient, and saurus.
The characteristics which seem to he marks of high grade
in these Thecodonts appear to be so implanted in a structure
otherwise low, that they must he regarded as foreshadowings
of the higher types rather than as marks of elevation.
The Palaeozoic character of the life of the Permian, as already shown, is
strongly marked. Geinitz observes, further, that the Ter'ebratula elongnta of the
Zechstein approaches a Devonian form; Camarophoria Schlotheimi (Zechstein)
is near the Carboniferous C. Crumena ; Spirifer Clannyanus (Zechstein), the Car¬
boniferous S. Urii; S. cristatus, the Carboniferous S. octoplicatus. The genus
Axintts (Schizodus) ends with the Permian, as well as Orthis, Camarophoria,
Productus, and Strophalosia.
GENERAL OBSERVATIONS.
377
GENERAL OBSERVATIONS ON THE PALAEOZOIC AGES.
I. Rocks.
1. Maximum thickness.—The maximum thickness of the rocks of
North America of the Silurian age is 22,000 feet; of the Devonian
age, about 14,400 feet; and of the Carboniferous age, nearly 15,000
feet.
2. Origin.—The fragmental rocks of the series—that is, the shales,
sandstones, and conglomerates—were made from pre-existing rock-
material through the agency of water, and mainly the waters of the
ocean. They were formed over the continents during their more
or less general submergence, and mostly in shallow waters or along
the borders of the land left uncovered by the sea.
The limestones were formed, without probably an exception, from
the calcareous relics of the living species. They were accumulated
generally in pure ocean-waters, like the coral limestones of the
present period ; and hence, while protected from the incursion of
detritus, perhaps, by barriers of some kind, they must still have had
open communication with the sea. But, as in the case of the coral
reefs, the waters, although sometimes deep, may generally have
been shallow, so that the waves could pei'form their part in grind¬
ing up and compacting the rising reef. When the shells are un¬
broken, there is sufficient evidence that the waters were too deep
for the heavy waves to reach them; but this does not necessarily
imply more than a depth of a few fathoms.
The liornstone, which is common in the limestones of the Palaeo¬
zoic in some parts of the country, is proved by the observations
mentioned on p. 270 to be mainly of organic origin. It is probable
that in all cases in which the fossils of a limestone are siliceous
(instead of calcareous) it is owing to the same cause that has origin¬
ated the chert,—namely, the presence, in great profusion, of the
siliceous remains of protophytes along perhaps with sponges.
3. Diversities of the different Regions of the continent with regard to the
kinds of rocks.—The three regions into which the portion of the con¬
tinent which has been especially considered is divided are (1) the
Interior Continental region, (2) the Appalachian region, and (3) the
Eastern border region. The rocks of the Appalachian region are
mainly fragmental, the limestones forming only a fourth of the whole
thickness. The strata of the Interior Continental basin are mostly
limestones, these constituting full two-thirds of the series. Although
New York is situated mostly within the Interior basin, it still adjoins
the Appalachian region, and partly lies within its border. Some idea
378
PALAEOZOIC TIME,
of the contrast between the two regions may be gathered from a
comparison of the section of the New York rocks, on p. 131, with
the general section of the formations in the Mississippi valley here
presented.
In the Lower Silurian of this section the Calciferous beds are
mainly of limestone, as well as the Trenton and the greater part of
Fig. 618.
Carboniferous..
subcarboniferous
Hamilton
U. IIelderberg....
Niagara |
Hudson River |
Trenton j
Potsdam 1
Permian.
Coal Measures.
Coal Conglomerate.
Subcarboniferous limestone.
Waverly sandstone (= Chemung
and Subcarboniferous).
Black shale.
Cliff limestone.
Blue limestone and shale.
Trenton limestone; Galena lime¬
stone; Black River limestone.
Lower magnesian limestone (==
Calciferous).
Potsdam sandstone.
Section of the Palaeozoic rocks in the Mississippi basin.
the Hudson. The Upper Silurian contains little but limestone; the
Lower Devonian and the Subcarboniferous are also limestone.
Moreover, many limestone beds intervene in the Coal measures;
and west of the Mississippi, over a considerable portion of the
Rocky Mountain slope the Carboniferous beds are mainly lime¬
stones.
The rocks of the northern border of the Interior Continental
basin towards the Azoic contain a much smaller proportion of lime¬
stone than those of the central portion.
The contrast between the Appalachian region and the Interior will become
more apparent from a few general sections. The first here given is from the
State of Pennsylvania, which lies within the Appalachian region ; it is from
the Geological Report of H. D. Rogers ; the second is a section of the Michi¬
gan rocks, by A. Winchell, lying on the northern side of the Interior basin ;
the third, of Iowa, which is also on the northern side, by Hall; the fourth and
GENERAL OBSERVATIONS.
379
fifth, of Illinois and Missouri, which are near its centre,—the former by A. H.
Worthen, the latter by G. C. Swallow, but with changes from more recent
information; the sixth, of Tennessee, the eastern part of which is in the Appa¬
lachian region, and the middle and western in the Interior, by J. M. Safford.
In each case the sections begin below.
1. Pennsylvania Section.
Lower Silurian.
Potsdam, Potsdam Epoch.—" Primal Series" of Rogers,—Sandstones and
Slates, 3000-4000 feet.
Calciferous Epoch.—"Auroral" Calcareous Sandstone, 250 feet.
Trenton, Chazy Epoch.—"Auroral" Magnesian Limestone, with some cherty
beds, 5400 feet.
Trenton Epoch.—" Matinal" Limestone with blue shale, 550 feet.
Hudson, Utica Epoch.—"Matinal" bituminous slate, 400 feet.
Hudson Epoch.—" Matinal" blue shale and slate, with some thin gray
calcareous sandstones, 1200 feet.
Upper Silurian.
Niagara, Oneida Epoch.—"Levant Gray" Sandstone and Conglomerate, 700
feet.
Medina Epoch.—"Levant Red" Sandstone and Shale, 1050 feet; and
" Levant White" Sandstone, with olive and green shales, 760 feet:
total, 1810 feet.
Clinton Epoch.—" Surgent Series," Shales of various colors, both argil¬
laceous and calcareous, with some limestones, ferruginous sandstones,
and iron-ore beds, 2600 feet.
Niagara Epoch.—Not well defined ; possibly corresponds to part of the
" Surgent" Series.
feALiNA, Saiiferous Epoch.—" Scalent" Variegated marls and shales, some layers
of argillaceous limestone, 1650 feet.
Lower IIelderberg.—-" Scalent" Limestone, thin-bedded, with much chert,
350 feet;" Pre-meridian" encrinal and coralline limestone, 250 feet:
total, 600 feet.
Devonian.
Oriskany, Oriskany Epoch.—" Meridian" calcareous shales, and calcareous and
argillaceous sandstone, 520 feet.
Corniferous, Cauda-Galli Epoch.—"Post-meridian" silico-calcareous shales,
200-300 feet.
Upper Helderhenj Epoch.—" Post-meridian" massive blue limestone,
80 feet.
Hamilton, Marcellus Epoch.—" Cadent" Lower black and ash-colored slate, with
some argillaceous limestone, 800 feet.
Hamilton Epoch.—"Cadent" argillaceous and calcareous shales and
sandstone, 1100 feet.
Genesee Epoch.—"Cadent" Upper black calcareous slate, 700 feet.
380
PALAEOZOIC TIME.
Chemung, Portage Epoch.—"Vergent" dark-gray, flaggy sandstones, with some
blue shale, 1700 feet.
Chemung Epoch.—" Vergent" gray, red, and olive shales, with gray and
red sandstones, 3200 feet.
Catskill.—"Ponent"red sandstone and shale, with some conglomerate, 6000
feet.
Carboniferous.
Sub carboniferous, Lower.—"Vespertine" coarse, gray sandstones and sili¬
ceous conglomerate at the eastward, becoming fine sandstones and
shales at the westward, 2660 feet.
Upper.—" Umbral" flne red sandstones and shales, with some limestone,
3000 feet.
Carboniferous, Millstone-Grit Epoch.—" Serai" siliceous conglomerate, coarse
sandstone and shale, with some fine argillaceous shales, including
coal-beds, 1100 feet.
Coal Measures.—Sandstone and shale, with some limestone, 2000-3000
feet.
2. Michigan (Lower Peninsula) Section.
Lower Silurian.
Potsdam, Potsdam Epoch.—" Lake-Superior Sandstone," mottled, reddish, or
dark and shaly, at Sault St. Mary, 18 feet; more to the westward,
250 feet.
Calciferous Epoch.—Rocks of this epoch said to exist,—character and
thickness not known.
Trenton, Chazy Epoch.—Gray siliceous limestone, 2 feet.
Trenton Epoch.—Blue and argillaceous limestone, with green calcareous
shale, 30 feet.
Hudson.—Argillaceous limestone underlaid by bluish-gray subcrystalline lime¬
stone, 18 feet or more.
Upper Silurian.
Niagara, Clinton Epoch.—Argillaceous, bituminous, and calcareous limestones,
51 feet.
Niagara Epoch.—White and gray limestones, massive and crystalline,
some layers arenaceous, others geodiferous, 97 feet.
Salina, Saliferous Epoch.—Brown and gray argillaceous limestones, calcareous
clay, and variegated gypseous marls, 37 feet.
Devonian.
Oriskany, OrisJcany Epoch.—Cherty, sometimes agatiferous conglomerate, 3
feet.
Corniferous, Upper Helderberg Epoch.—Brecciated limestone, 250 feet; over¬
laid by oolitic, arenaceous, and bituminous limestones, 104 feet: total,
354 feet.
GENERAL OBSERVATIONS.
381
Hamilton, Marcellns (?) Epoch.—Black, bituminous limestone, 15 feet.
Hamilton Epoch.—Argillaceous limestones, 17 feet; crystalline lime¬
stone with included lenticular clayey masses, 23 feet: total, 40 feet.
Contains a bed of coal on Little Traverse Bay.
Genesee (?) Epoch.—Black, bituminous shale, 20 feet,
Chemung, Portage Epoch.—"Huron" shales with intercalated flagstones and
limestones, 190 feet.
Carboniferous.
Subcarboniferous, Lower.—"Huron" and "Marshall" (= Chemung?) grit¬
stones, and reddish, yellowish, and greenish sandstones find conglome¬
rates, 173 feet; "Napoleon sandstone," generally micaceous, with
clay beneath, 123 feet; "Michigan Salt-group," carbonaceous and
argillaceous shales, magnesian and arenaceous limestones, and thick
beds of gypsum, 184 feet: total, 480 feet.
Upper.—Limestones, arenaceous below, 66 feet.
Carboniferous, Millstone-Grit Epoch.—"Parma" thick-bedded sandstone, in
some places conglomeritic, 105 feet.
Coal Measures.—Bituminous shales, and fire-clays, with occasional thin
sandstones and limestones, 123 feet; " Woodville" sandstone, 79 feet:
total, 202 feet.
3. Iowa Section.
Lower Silurian.
Potsdam, Potsdam Epoch.—Very pure sandstone, with some thin, calcareous,
shaly layers, 500 feet.
Calciferous Epoch.—"Magnesian" limestone, almost chemically pure,
sometimes brecciated and concretionary, 250 feet or more.
Trenton, Chazy Ep>och.—"St. Peter's Sandstone," a granular, rarely compact
sandrock, 80 feet.
Trenton Epoch.—" Buff," " Blue" and " Galena" magnesian limestones,
with some shaly portions in the lower layers, 350 feet.
Hudson, Hudson Epoch.—Siliceous and argillaceous shales, mostly bituminous,
80-100 feet.
Upper Silurian.
Niagara, Clinton and Niagara Epochs.—Light yellowish-gray compact magne¬
sian limestone, with much chert, 150-300 feet.
Salina, Leclaire Epoch.—Gray semi-crystalline porous limestone, 600-700 feet.
Saliferous Epoch.—Thin-bedded, drab-colored limestones, with shaly
partings, 100-150 feet.
Devonian.
Corniferous, Upper Helderberg Epoch (?).—Gray compact limestone, with
some concretionary and shaly layers, 50 feet or more.
Hamilton, Hamilton Epoch (?).—Magnesian limestones, 100 feet.
Chemung, Chemung Epoch.—[Subcarboniferous in part?] Siliceous shales, some¬
times calcareous, 100 feet or more.
382
PALAEOZOIC TIME.
Carboniferous.
Subcarboxiferous.—Consisting of—1st, "Burlington" subcrystalline encri-
nital limestone, 100 feet or more; 2(1, " Cherty" limestone, 100 feet;
3d, " Keokuk" bluish-gray limestone, with thin beds of shale, 40 feet,
and calcareous shale filled with "geodes,"40 feet; 4th, "Warsaw"
magnesian limestone, succeeded by shaly limestone and coarse, cal¬
careous sandstone, 40 feet; 5th, " St. Louis" limestone, commonly
brecciated and concretionary, in some parts compact, 20 feet or
more: total, 340-400 feet.
Carboniferous.—Shale, sandstone, clay, and limestone, less than 500 feet.
4. Illinois Section.
Lower Silurian.
Potsdam, Calciferous Epoch.—Buff magnesian limestone, with beds of earthy
hydraulic limestone, 100 feet or more.
Trenton, Chazij Epoch.—" St. Peter's Sandstone," brown and white friable
sandstones, in some places concretionary, 150 feet.
Trenton Epoch.—" Trenton" and " Galena" brown magnesian limestones,
thin-bedded blue limestones, and massive gray granular limestones,
300 feet.
Hudson, Hudson Epoch.—Shales, shaly sandstones, and dark-blue limestone,
100 feet.
Upper Silurian.
Niagara.—Buff and gray magnesian limestone, some cherty beds, 300 feet.
Devonian.
Oriskany.—Quartzose sandstone, becoming locally calcareous, 50 feet.
Hamilton, Hamilton Epoch.—Coralline limestone and shale, dark-colored fetid
limestone, 120 feet.
Genesee Epoch.—" Black Slate," bituminous shales and slates, 40 feet.
Carboniferous.
Subcarboniferous.—Consisting of—1st," Kinderhook" arenaceous and argilla¬
ceous shales with local beds of limestone, 100 feet; 2d, " Burlington"
light-gray limestones with chert, and brown, arenaceous limestones,
200 feet; 3d, " Keokuk" calcareo-argillaceous shales with geodes,
gray limestones, and chert, with seams of stratified marly clay, 100
feet; 4th, "Warsaw" and "St. Louis" bluish-gray limestone, concre¬
tionary and brecciated beds, impure limestones and clay shales, mag¬
nesian limestone, 200 feet; 5th, massive " Ferruginous" sandstone ot
even texture, 100 feet; 6th, " Chester" limestones, separated by heavy
beds of clay shale, which pass locally into sandstone, 250 feet: total,
950 feet.
Carboniferous, Millstone-Grit Epoch.—Sandstone and conglomerate, 300 feet.
Coal Measures.—Sandstones and shales, with thin bands of limestone
and five or more coal-seams, 900 feet.
GENERAL OBSERVATIONS.
383
5. Missouri Section.
Iiower Silurian.
Potsdam, Calci/erous Epoch.—Alternations of crystalline and compact "Mag-
nesian Limestones," and white or gray pulverulent or firm "Saccha-
roidal Sandstones," 1300-1500 feet.
Trenton, Trenton Epoch.—Bluish-gray and drab compact limestone, with con-
choidal fracture; buff and gray crystalline limestone, much decomposed
on exposure ; some blue shale; 435 feet; overlaid by " Receptaculite"
argillaceous subcrystalline limestone, 130 feet: total, 505 feet.
Hudson, Hudson Epoch.—Two beds of blue and gray argillaceous magnesian
limestone, 60 feet, separated by blue and purple shales, 60 feet:
total, 120 feet.
Upper Silurian.
Niagara, Niagara Epoch.—Compact magnesian and argillaceous limestone,
150 feet.
Lower IIelderberg.—Light-gray magnesian limestone, 100 feet.
Devonian.
Oriskany.—Light-gray, nearly pure limestone,—thickness not given.
Corniferous, Upper Helderberg Epoch.—Gray, compact, earthy limestone with
chert and some sandstone; in some parts a hard white oolite, 75 feet.
Hamilton, Hamilton Epoch.—Blue argillaceous shale, with thin layers of con¬
cretionary limestone, 50 feet.
Genesee Epoch.—Black slate, 6 feet.
Next follow beds which have been referred by some to the Chemung
group, by others to the Subcarboniferous,—viz.: 1st, Light-drab, fine,
compact "Lithographic" siliceous limestone, 70 feet; 2d, buff, fine¬
grained, pulverulent, argillo-calcareous sandstone, with some magne¬
sian limestone, underlaid by blue or brown argillaceous shale, 100
feet; 3d, fine, compact limestone, overlaid by brown silico-magnesian
limestone, 70-120 feet: total, 250-300 feet.
Carboniferous.
Subcarboniferous.—1st, " Encrinital," brown, buff, gray and white, coarse
crystalline heavy-bedded limestone, everywhere containing chert,
500 feet; 2d, "Archimedes" gray and drab crystalline and compact
limestone, with some silico-argillaceous limestones and blue shales,
200 feet; 3d, "St. Louis" hard, crystalline, gray, cherty limestone,
with thin beds of argillaceous shale, 250 feet; 4th, " Ferruginous"
brown and red, coarse, friable sandstone, in some parts white and
" saccharoidal," 200 feet: total, 1150 feet.
Carboniferous, Coal Measures.—Blue and gray compact limestones, with
black, blue, and purple bituminous and calcareous shales, and a few
thin beds of coarse sandstone, 250 feet or more.
384
PALAEOZOIC TIME.
6. Tennessee Section.
Lower Silurian.
Potsdam, Potsdam Epoch.—" Chilhowee" sandstones and sandy shales, at least
1000 feet in east Tennessee.
Calciferous Epoch.—Pine sandstones and shales, with magnesian lime¬
stone: sandstone member (lowest), 600-1000 feet in east Tennessee;
shales, 1500-2000 feet; limestone, 3500-3800 feet.
Trenton, Trenton Epoch.—" Stones River" blue and dove-colored limestones,
with more or less chert, 500-600 feet in east Tennessee-, lower part
of "Nashville Group."
Hudson, Utica and Hudson Epochs.—Upper part of "Nashville Group," calca¬
reous shales and argillaceous limestones, including beds of fine marble,
1000-2000 feet in east Tennessee.
Upper Silurian.
Niagara, Medina Epoch.—"Clinch Mountain" white and gray sandstone, and
"White Oak Mountain" brown sandstones and shales, 800-1000 feet.
Clinton Epoch.—" Dyestone Group," variegated calcareous shales with
some sandstone, 200-300 feet in east Tennessee.
Niagara Epoch.—" Sneedville" gray limestone, 200 feet thick.
Lower IIelderberg.—Gray crinoidal limestone, 75-100 feet in middle Ten¬
nessee; absent elsewhere (?).
Devonian.
Hamilton (?), Genesee Epoch.—"Black Slate," a brownish-black slate, often
pyritiferous and bituminous, 100 feet or more in east Tennessee.
Carboniferous.
Subcarboniferous, Lower.—" Siliceous Group," shales and sandstone, 400 feet
at Cumberland Gap (perhaps Upper Devonian); blue and gray lime¬
stone, mostly cherty, with some shale, 300-550 feet.
Upper.—" Mountain" limestone, blue, thick-bedded, and in great part
oolitic, 500-750 feet in middle Tennessee.
Coal Measures.—Sandy conglomerates, sandstones with six or more coal-
beds, and shales, 2500 feet or more in middle Tennessee.
In the Eastern border region, about the Gulf of St. Lawrence (which
was probably an interior basin like the Interior Continental) there
were limestones forming almost continuously from the Calciferous
epoch in the Lower Silurian to the close of the Clinton epoch in the
Upper Silurian, which is the last of the formations there observed.
With regard to other parts of the Eastern border region our know¬
ledge is yet imperfect, and in great measure because the crystalli¬
zation which the rocks have undergone has obliterated most of
their original features. This is the case over New England and the
GENERAL OBSERVATIONS.
385
border of the continent south of New York. Besides this, a strip
of land some eighty miles wide, constituting the eastern margin of
the continental plateau, is still under water (p. 12). The map,
fig. 664, gives a general view of the breadth and depth of this pla¬
teau off the coast of New Jersey.
4. Diversities in the different regions as to the thickness of the rocks.—The
maximum thickness mentioned on p. 377—50,000 feet—occurs in
the Appalachian region. It is not found in any one place; for
some of the formations are thickest along the middle of the region,
others on the western side, and still others on the eastern ; and,
again, the beds of the Carboniferous age are most largely developed
to the northeast in Nova Scotia. Owing to facts like these, the
maximum amount exceeds considerably the actual thickness of the
accumulations over the region. Still, it cannot be less than 36,000
feet, or 6£ to 7 miles. Each of the successive formations in the
Appalachian region is remarkable for its great thickness from the
Potsdam upward.
In the central portions of the Interior Continental basin the
thickness varies from 3500 (and less on the north) to 6000 feet.
It is, therefore, from one-sixth to one-tenth that in the Appalachian
region.
Another region of unusual thickness lies on the north side of the
Interior basin, near the Azoic. Along Lakes Superior and Huron
the fragmental Iluronian beds in the closing part of the Azoic age
accumulated to a thickness of 10,000 feet; and in the latter part of
the Potsdam period the Calciferous beds in some places about the
former lake have a thickness of 3000 to 4000 feet. Again, in the
region of the St. Lawrence, about Ottawa, the Potsdam beds have
twice the thickness they exhibit in the State of New York, and the
Trenton in Canada are three times as thick, or nearly 1000 feet,—an
unusual thickness for a limestone formation.
In Missouri, during the Calciferous epoch, in the Potsdam period,
the accumulations had the great thickness of 1300 feet,—an excep¬
tion to the usual fact in the Interior Continental region.
Relative duration of the Palaeozoic ages.—The thickness of the series
of rocks pertaining to the several ages affords some data for esti¬
mating their time-ratios. The results are necessarily uncertain, since
the increase of a rock is often directly connected with the subsi¬
dence there in progress, as has been elsewhere explained. Still,
the conclusions are sufficiently reliable to be here presented.
Taking the maximum thickness along the Appalachians of the
successive formations (the limestone and fragmental beds in each
case from the same region), we find for the
26
386
PALAEOZOIC TIME.
Fragmental rocks.
Limestones.
1. Potsdam period
2. Rest of Lower Silurian
6,800
1,600
8,400
200
6,000
6,200
600
100
125
3. Lower Silurian era,
4. Upper Silurian era,
5. Devonian Age
14,300
14,600
6,760
6. Carboniferous Age
Limestones increase with extreme slowness, as explained in the
chapter on coral islands. From five to ten feet of fragmental de¬
posits will accumulate while one of limestone is forming. This con¬
clusion is sustained by the ratio in any given period between the
fragmental rocks of the Appalachians and the limestones of the
Interior basin.
Taking the ratio as 5 to 1, and making the substitution accord¬
ingly, the numbers are, respectively, (1) 7800; (2) 31,600; (3)39,400;
(4) 9760; (5) 14,800; (6) 15,225. These numbers have nearly the
ratio 1:4: 5 : 1J : 2: 2. Hence, for the Silurian, Devonian, and Car¬
boniferous ages, the relative duration will he 6}: 2: 2, or not far
from 3:1:1. If the ratio 8 to 1 be taken, these numbers become
4:1:1.
According to these calculations, the American Lower Silurian era
was, by the first estimate, four times as long as the Upper; by the
second, five times ; and the duration of the Silurian age was three or
four times that of either the Devonian or the Carboniferous. The
earth thus dragged slowly on through its earliest periods.
1. General course of progress.—Through the Palseozoic ages, the
dry land of the closing Azoic age (map on p. 136) gradually ex¬
tended southeastward, southward, and southwestward. At the end
of the Silurian, the limit of the dry land appears to have had its
position near the central east-and-west line of the State of New
York; and at the close of the Devonian it lay not far from the
southern border of the State. Westward, beyond Michigan, in Illi¬
nois, Iowa, and Minnesota, there was a like expansion to the south
and west of the Wisconsin Azoic. Michigan long continued to be
a part of the oscillating Interior basin, the Palseozoic formations
being continued there even to the close of the Coal period.
Along the St. Lawrence the Ottawa basin was nearly obliterated
at the close of the Lower Silurian (p. 228). In the latter half of the
Upper Silurian the river opened into a St. Lawrence gulf over the
site of Montreal, and in its waters a Lower Helderberg limestone
II. American Geography.
GENERAL OBSERVATIONS.
387
was formed. In the Devonian age the head of the gulf was still
farther to the northeast,—probably in the vicinity of Quebec,—and
opened southward over New England; for coral reefs were growing
in the region of Lake Memphremagog during the earlier Devonian
(p. 270).
South of the eastern half of the St. Lawrence there appears to
have been a progress of the dry land southward, similar to that over
New York and the West; for the Silurian and Devonian beds are
successively passed over in going towards New England. There is
reason for believing, as different geologists have urged, that the
granites and schists of the White Mountains were made of strata of
the Devonian age. Still farther south, beyond Worcester, in Mas¬
sachusetts, and over Rhode Island, lay the Carboniferous marsh or
coal-making area of the New England basin ; while to the north¬
east, over part of Nova Scotia and New Brunswick, there were the
far larger marshes of the Acadian basin: the two belong geographi¬
cally to the same great region—then low—between the St. Law¬
rence and the ocean, and probably had direct connection.
After the Devonian, and the Subcarboniferous period in the next
age, the dry land expanded to nearly its present extent, and it be¬
came covered with forests, jungles, and marshes of Carboniferous
vegetation. This condition oscillated with that of marine submer¬
gence many times in the progress of the Coal period. But the dry
land appears to have reached a degree of permanence in the Appa¬
lachian region after the Pittsburg Coal series, and, to a still wider
extent, throughout the whole interior east of the Mississippi, after the
Upper Coal beds (p. 368), so that when the Carboniferous period
closed, the continent in this its eastern half was almost complete.
Over the whole surface, including New England, Canada, and the
British possessions eastward, no rocks occur between the Palaeozoic
and Cretaceous, excepting small strips of Mesozoic east of the Alle-
ghanies, and also in the Connecticut valley and Nova Scotia.
The interior sea, which in Silurian and Devonian periods had
spread from the Gulf of Mexico over the whole Interior Continental
basin and stretched northward on the west side of the Azoic nu¬
cleus to the Arctic, after many variations eastward and westward
in its extent through the whole Palaeozoic, was at last mostly limited
to the region west of the Mississippi, and the southern portion of
the Mississippi valley; for here are located all the marine sediment¬
ary deposits of the interior formed in later time.
2. Mountains.—The mountains of the Palaeozoic continent were
mainly those of the Azoic,—the Adirondack, of northern New
York, other heights in British America, the Black Hills, and iso-
388
PALAEOZOIC TIME.
lated ridges in the seas of the Rocky Mountain region, etc. The
Carboniferous marshes covered a large part of the site of the Alle-
ghanies, and a sea in which Carboniferous limestones were forming,
a considerable portion—perhaps all but the Azoic heights—of the
area of the Rocky Mountains.
But after the close of the Lower Silurian the Green Mountain re¬
gion appears to have been above the sea (pp. 228, 243), and divided
the New England or Eastern border region from the Interior. Conse¬
quently, the subsequent progress of the dry land over New England
was from the Green Mountain region eastward, as well as from the
St. Lawrence southward. In other words, the Devonian beds which
stretch from Gaspe to Vermont, thence bend southward on the east of
those mountains, as has been suggested by the geologists of Canada.
3. Rivers.—The rivers of the early Paheozoic were only small
streams, such as might have gathered on the limited Azoic lands.
In the later Devonian and the Carboniferous, they included the
Hudson and St. Lawrence (p. 300). But even to the last, the region
of the great streams of the Rocky Mountains was still a part of the
interior sea; the Mississippi had but a part of its length, and this
only temporarily, as the country was often submerged. The valley
of the Ohio River was in part the region of the interior Carbonife¬
rous marshes: as the mountains in which it rises were not yet
raised, the river cannot have existed. Moreover, the Cincinnati
uplift (p. 228), which stretched southwestward into Kentucky and
Tennessee, and may date from the beginning of the Upper Silurian,
probably divided the great interior marshes about the upper Ohio
region from those of the lower.
III. Oscillations of level.—Dislocations of the strata.
1. General subsidence.—The earliest Silurian beds—the Potsdam—
bear abundant proof, in ripple-marks, sun-cracks, and wind-drifts,
of their formation near the water-level. Many of the succeeding
strata of the Silurian and Devonian periods contain the same evi¬
dence, and lead to the same conclusion for each ; and later, in the
Carboniferous formation, many layers show in a similar manner that
they were spread out by the waves, or within their reach. Conse¬
quently, when these last layers of the Palaeozoic in the Appalachian
region were at the ocean's level, the Potsdam beds—though once
also at the surface—were about seven miles below ; for this is the
thickness of the strata that intervene: seven miles of subsidence
had, therefore, taken place in that region during the progress of
the Palaeozoic ages.
GENERAL OBSERVATIONS.
389
From analogous facts it is learned that the subsidence in the
Interior Continental basin was about one mile, instead of seven.
In the lower peninsula of Michigan it was at least 2500 feet; in
Illinois, 3000 to 4000 feet; in Missouri, 5000 to G000 feet.
On the northern border of the Interior basin, near the Azoic, the
thickness of the Lower Silurian indicates a great subsidence in
that era which was not afterwards continued. Thus, in the vicinity
of the great lakes, the 10,000 feet of the Iluronian in the last part
of the Azoic age, and the 4000 of the Potsdam period, teach that
near the beginning of Palaeozoic time this was a region of un¬
usual subsidence; and the igneous rocks that intersect and inter-
laminate the sedimentary strata evidently came up through the
fractures that accompanied, or were occasioned by, the subsidence.
In Western Canada, between the stable Azoic of Canada and New
York, the 1000 feet of Trenton limestone, and 700 feet of Calci-
ferous and Potsdam beds, prove that there was a great subsiding
also in that region, while little occurred south of the New York
Azoic. After the Lower Silurian, this subsidence in the vicinity of
the Azoic for the most part ceased.
In Missouri, also, where again there is a patch of Azoic, the
thickness of the formations of the Potsdam period was 1500 feet
or more.
All the numbers here given, both for the Appalachian region and
the interior, are probably below the actual fact; for the strata may
in many cases—especially along the Appalachian region—have
lost much of their original thickness by denudation, either before
or after they were consolidated. This loss may have been one-
fourth the whole ; but, whatever its extent, it probably has not
altered the proportion of subsidence between the Appalachian
region and the interior.
2. Oscillations.—The succession of sandstones, shales, and lime¬
stones in the Palaeozoic series have been explained to be indica¬
tions of as many changes in the water-level of the continent. The
prevalence of limestones over the Interior basin has pointed out
the region as an extensive reef-growing sea, opening south into
the Atlantic, and perhaps also the Pacific, for the larger part of
Palaeozoic time. But there were slow oscillations in progress that
changed the limits of the formations to the eastward or westward,
as the periods succeeded one another.
The Potsdam sandstone covers both the Appalachian region and the Interior
basin.
The Calciferous beds also stretched over both, but were partly limestone in
the east, and mostly so in the west.
390
PALAEOZOIC TIME.
The Trenton spread over both, with perhaps the exception of the Green
Mountain portion ; and, throughout, it was almost solely limestone.
The Hudson formations cover both, with the same exception as in the case of
the last; but they are shales in the East, and limestones mainly in the West.
The preceding are the universal formations. Passing now to the Upper
Silurian:— '
In the Niagara period, the Oneida conglomerate occurs in central New York
and along the Appalachians ; the Medina beds have nearly the same position,
but also spread over Canada, west of New York, and are sandstones and marls;
the Clinton beds have approximately the same eastern distribution, but spread
farther to the west along the northern portion of the Interior basin, reaching to
Wisconsin,—and, while mostly arenaceous in the East, they are in general calca¬
reous in the West; the Niagara limestone has again the same position over
central New York and the Appalachians, but extends over nearly the whole
Interior basin, showing an expansion or change in the interior sea; and its
rocks, excepting those of the Appalachians, are mainly limestones.
In the Salina period, there is the same extension of the formation from the
Appalachians north over central New York, but to the west it spreads only along
the north, where it reaches to Iowa ; the rocks on the east are marls and sand¬
stones, and those of the West mostly limestone.
In the Lower Heldcrberg period, the rocks stretch from central New York
southwestward along the Appalachians, and do not spread much to the west of
New York and Canada. The rock is a limestone,—the first of any extent in the
Appalachians of Pennsylvania since the Trenton.
This extension of the Appalachian strata northward over central New York,
and their maximum thickness there for those latitudes, have been accounted for
on the supposition that the Green Mountain region became a part of the com¬
paratively permanent dry land after the close of the Lower Silurian (pp. 228, 243),
and, consequently, the oscillating area was transferred a little farther to the
westward. It, however, did not reach north to the Azoic of New York, which
was still a portion of the stable part of the continent.
In the Devonian age :—
The Oriskany formation was mainly confined to central New York and the
Appalachians, but some thin beds occur in the Mississippi basin: the rocks are
mostly sandstones.
The Upper Helderberg was the coral-reef period, and limestones were spread
over the larger part of the Interior basin, and also over the Appalachians.
The Hamilton beds were extensive in central New York and along the Appa¬
lachians, but very thin to the westward over the interior: the " black slate" of
the Genesee epoch is its thickest portion, and this is remarkable for its wide
distribution over the Interior basin, and its persistent uniformity of character,—
which proves that it must have been formed in waters of very uniform depth,
either very shallow or somewhat deep,—probably the former.
The Chemung and Portage beds have great thickness in southern New York
and the Appalachians, and are very thin to the west, and in many parts want¬
ing : they are sandstones.
In the Carboniferous age :—
The Subcarboni/erous formations are thousands of feet thick in the Appa-
GENERAL OBSERVATIONS.
391
laehians of Pennsylvania, and consist of sandstones, shales, and conglomerates
with little limestone; in those of Virginia, the limestones are of great thick¬
ness : the formations cover the Interior basin, and are almost wholly of lime¬
stone, the lower part only being arenaceous or siliceous.
The Carboniferous Millstone grit is a conglomerate of great extent in the
Appalachians, mostly a sandstone in Ohio, and is nearly wanting in the Mis¬
sissippi basin. The Coal measure beds are shales and sandstones with little
limestone in Pennsylvania and Ohio; shales and sandstones with considerable
limestone in the Mississippi basin east of Kansas; and mainly limestone west
of Kansas.
This brief sketch of the limits of the formations gives an idea of the great
oscillations in the sea-level during the progress of the Palaeozoic : it is not
necessary to dwell upon its details, as the conclusions may be readily drawn by
the reader after the explanations, under the head of General Observations, in the
preceding pages. The Eastern border region has here been left out. of view.
Until the close of the Subcarboniferous period, the oscillations
had that wide continental range which was eminently characteristic
of the American Paleeozoic. In the period following, the Carbo¬
niferous, the continent for prolonged periods stood raised just
above the ocean, at a nearly uniform level,—so low that, its inte¬
rior was covered with immense fresh-water marshes, and for so
long eras that the vegetable accumulations attained the thickness
sufficient for coal beds (p. 360); but these emergences had their
alternation with submergences. The system of oscillations, though
slower in movement, was still continued ; yet the movements were
less general; and it is therefore difficult to make out a parallelism
in the beds of coal and intervening rock-strata through the East
and West.
3. Uplifts and dislocations.—The only mountain-region along the
course of existing chains which can now be pointed to as having
emerged during the Palteozoic ages, is that of the Green Mountains.
This region probably became part of the stable dry land in the in¬
terval between the Potsdam period of the Lower Silurian and the
commencement of the Upper Silurian er»,
The crystalline limestones of western iSew England have been
referred to the Calciferous epoch. They extend from Connecticut
through Massachusetts (in which State the Stockbridge quarries
are most noted), and nearly to the northern limit of Vermont;
and in Vermont, where they have been called. " Eolian" limestones,
they have, according to Hitchcock, a thickness of 2000 feet. If
actually Calciferous, the emergence of the Green Mountain region
may have taken place before the Trenton period, since no Trenton
rocks in that case were formed over it. The fossils have in general
been obliterated by the crystallization of the rock. But the Ver-
392
PALAEOZOIC TIME.
mont rock at Sudbury and elsewhere has afforded a few fossils, and
these favor its belonging to the Trenton period, as long since held
by Rogers. Among them there is a Cyatliophylloid coral; and none
of similar character is known before the Pctraia of the Tren¬
ton limestone; also species referred to Chcctctes, Stromatopora (or
Stromatoccrivm), Stictopora, and Euomphalus. In its great thickness the
limestone differs vastly from that of the Calciferous beds of the
Quebec group, and has its only counterpart in the Appalachian
region in the limestones of the Trenton period in Pennsylvania,
which are nearly 0000 feet thick. Admitting this age for the lime¬
stones, the Green Mountain region did not become dry land until
the close of either the Trenton or Hudson period.
Besides an emergence of the western part of the Green Mountain
region at the close of the Lower Silurian, there probably also
occurred the metamorphism of its rocks, making the shales and
earthy limestones into hard slates and crystalline limestones, to be
afterwards overlaid unconformably by later beds. It was probably
at this time that the Stockbridge Eolian limestone became a statuary
marble and its fossils were almost entirely obliterated. In the
same operation, the rocky crust may have received that stiffening
which made it a part of the permanent dry land, like the adjoining
Azoic, and in consequence of which a district over which a sub¬
sidence of many thousands of feet took place in the Lower Silurian
(p. 176) participated but little in the later Appalachian move¬
ments.
The Ottawa basin and the subsiding area of Keweenaw Point on
Lake Superior also became comparatively stable before the Upper
Silurian era began (pp. 199, 228).
In a few places there were dislocations of the strata after the close
of the Lower Silurian, and again others before the Coal period.
These are mentioned on pp. 227, 320. But in general the strata
from the bottom of the Silurian to the top of the Carboniferous
make an unbroken series, with no unconformability except the
slight want of parallelism the great oscillations at times occasioned
(p. 320). The great extent of the series, and the vast length of time
occupied by those passing ages, make this exemption from great
disturbances a subject of profound importance in American geo¬
logical history.
4. Direction of oscillations.—The direction of the great oscillations
of the continent may be learned from the course of the region
along which, through the successive periods, the greatest amount
of change of level took place. One such region is the Appalachian,
in which the subsidence, as has been shown, amounted in some
GENERAL OBSERVATIONS.
398
parts to seven miles or more, while parallel with it in the Interior
basin the average was comparatively small. The review of the limits
of the successive formations, on p. 379, shows that even the minor
changes took place under the influence of oscillations having this
general course.
The Lower Silurian uplift from Cincinnati to Tennessee conforms
to this system. In accordance also with it, the Coal measures in
Pennsylvania, to the top of the Pittsburg series, were elevated so
that their marshes became dry before the higher beds were laid
down; and these upper beds, with the whole region west to the
Mississippi, before the Permian (p. 371).
The Appalachian region, including from the Gulf of St. Lawrence
to Alabama, lies parallel with one great branch of the Azoic dry
land, C C, on map, p. 130, and also with the Atlantic Ocean. The
Appalachian oscillations therefore conformed in direction with one
of the two Azoic systems (p. 147): they were but a continuation
of the series that prevailed while the Azoic age was in progress.
With regard to the region west of the Azoic, our information is
yet scanty: sufficient, however, is known to make it apparent that
the increase of dry land was from the Azoic to the southwest, or
corresponding to oscillations parallel to the Rocky Mountains.
The direct effect of such oscillations is manifest in the Illinois
uplifts preceding the Coal measures, for they are parallel to the
Rocky Mountain chain and the Pacific coast-line. This, then,
was a second grand direction of oscillations. It was parallel with
the northwestern branch of the Azoic, B B, on map, p. 136, and
corresponded to the second of the two series that prevailed during
the Azoic age.
It is hence apparent that, whatever the forces at work in Azoic
time, they continued to act in the same general direction through¬
out the Pakeozoic. The action of the two systems of forces to¬
gether evidently produced the great amount of subsidence adjoin¬
ing the Canada Azoic, where the thick deposits of the Huronian
and Potsdam periods were formed, and where finally the basins of
the great lakes were made. These, and nearly all the lakes of North
America, lie near the limit between the oscillating part of the con¬
tinent and the stable Azoic.
5. Cotemporancous movements in the American and European continents.—
The fact that the continent of Europe was above the ocean, and
in that condition which was characteristic of the Coal period, at
the same time with North America, shows a cotemporaneousness
in the oscillations of the crust on the opposite sides of the Atlantic
Ocean. This concordance will be better apprehended when it is
394
PALiEOZOIC TIME.
considered that the land must have been but little elevated, and
quite uniformly so,—enough to drain the great salt marshes of their
salt, and not so high as to turn them into dry fields. It was not suf¬
ficient that there should be land and Carboniferous vegetation ; for
without the wet, swampy lands—wet with fresh waters, and very
wide in extent—the great accumulations of vegetation and im¬
mense coal fields would not have been made.
There is a similarity between the continents, also, in the character
of the oscillations which occurred in the course of the Carboni¬
ferous period, which submerged the land after material for a coal
bed had accumulated, and buried it for long keeping beneath sand¬
stones and shales, and then brought it again to the surface for
renewed verdure and another coal bed; and so on in many succes¬
sions.
The Millstone grit, which preceded the Coal measures in Europe
as well as America, is evidence of a degree of correspondence in
that upward movement of the continents through the waves which
ushered in the epoch of the Coal Measures ; and the prevalence
and wide distribution of the limestone of the Subcarboniferous
period, which next preceded, mark another cotemporaneous move¬
ment,—a very general submergence preceding the emergence just
alluded to. Moreover, in both continents, some thin coal beds
were formed in the Subcarboniferous period.
Contrast between America and Europe.—While the two continents
were at times concordant in their general movement, there was
apparently a contrast during the Coal period in the moisture of the
two, which may in part, at least, be attributed to climate. This is
apparent in the vastly larger coal fields of America. Guyot has
called America the forest-continent, a character it now bears because
of its moist climate, or more abundant rains ; and it is probable
that it presented this peculiarity with the first appearance of vege¬
tation over its surface.
IV. Life.
1. System of progress.—The Animal kingdom began with Radiates,
Mollusks, and water Articulates ; included Fishes, the lower Ver¬
tebrates, in the Devonian; and Reptiles in the Carboniferous age.
With each period the progress was upward towards a fuller and
higher display of the system of life.
It is important to observe, in this connection, that the length of the Age
of Mollusks, or Silurian age, as shown on p. 38(5, was three or four times that
of either the Devonian or the Carboniferous. This fact, in connection with
GENERAL OBSERVATIONS.
395
the abundance of the remains of fishes in the Devonian, makes their absence
from the American Silurian, and from all the foreign below the Upper Ludlow
beds, the more striking, and adds force to the conclusion that no fishes existed
during that era. And the same holds true with regard to the absence of Rep¬
tiles from the Devonian age. On this ground alone, the supposed discovery by
Pander of microscopic teeth of fishes, in the Russian Ungulite grit, of the Lower
Silurian, with no knowledge of fish-relics elsewhere in the Silurian of America
or Europe, would be reasonably questioned, were it not also proved that these
so-called teeth were not ichthyic, but probably from the dental apparatus of Gas-
teropods.
It is an error, as the facts reviewed have shown, to suppose that
the system of life commenced with the lowest forms, and reached
always a higher grade with each new development, The following
are some of the principles bearing on this progress which have
been exemplified in Palaeozoic history.
(l.)The earlier species were water species, and all of them marine.
Radiates and Mollusks the water Articulates, and Fishes the
water Vertebrates, comprise all known species of animals until
the close, or nearly the close, of the Devonian; and Sea-weeds all
the plants to the close of the Silurian. In all divisions of the
kingdoms of life the species made for the water are of inferior
grade.
(2.) Many of the earlier types were of the kind called comprehensive
types, as explained on pp. 203, 302.
Trilobites and the Ganoid fishes have been mentioned as ex¬
amples. Other examples are—the Labyrinthodont Reptiles, which
comprehended, along with the structure of the Amphibian, the
scaly covering and some other peculiarities of the higher Rep¬
tiles ; the large Lepklodendrids of the Coal era, which combined
with the characteristics of the Cryptogams the foliage and general
habit of the Conifers; the Sigillarids, which presented the general
structure of the Conifers, with a habit and foliage that approxi¬
mated them to the Lycopodia; the Catamites, which possessed
the habit of the Equiseta among Cryptogams, united, in some
species at least, according to Brongniart, to a woody texture ap¬
proaching that of the Sigillarids; and, in the early Silurian, the
Cystideans among Radiates, which often had a want of radiate
symmetry almost as great as characterizes Mollusks. and also some
features of the later Ecliinoids joined with the essential structure
of the Crinoids.
These comprehensive types, as is apparent in the examples, do not
occupy a middle point between two of the general divisions of the
Animal kingdom: on the contrary, they belong fundamentally to
one, while partaking of some of the characteristics of the other.
396
PALAEOZOIC TIME.
They are called by Agassiz, who early recognized their nature, syn¬
thetic types,—a term not here used, as it implies that they corre¬
spond to a combination of what was before separate, rather than to
one yet undivided. Guyot calls them undivided types.
(3.) The starting-point of a class or other division of the kingdoms
of life was often from the top of its lower division and the bottom of
the next above, or from an intermediate level between the two.
Dividing plants into Cryptogams and Phsenogams; Crustaceans
into Entomostracans, the lower, and Malacostracans, the higher
group, as done by Cuvier; Reptiles into Amphibians and true
Reptiles; Vertebrates into water-breathing and air-breathing: we
observe that—
The earliest land-plants were the highest of the Cryptogams and
the lower of the Phamogams (the Gymnosperms), together with
groups that are intermediate and of the nature of the comprehen¬
sive types above described (see p. 333). The vegetable kingdom
began with the lowest of its tribes, the Algfe, or Sea-weeds, and pro¬
bably with the lowest of sea-weeds as far back as theAzoic age. But
when terrestrial plants were to appear, there was not a series rising
in grade from these sea-weeds up to the higher species of the land.
On the contrary, the lower Cryptogams of the tribes of Mosses,
Hepaticee, and even the fresh-water Confervse, were passed by, and
the new species were those at the top of the order of Cryptogams,
with others superior to the modern types of this order.
The early Crustaceans, Trilobites, belonged either to the top
of the Entomostracans or to the bottom of the higher group, and
presented features of both. (See p. 202.)
The earliest Reptiles were not the lowest of Amphibians; but
along with some of the inferior species of this division there were
Labyrinthodonts, a family above the true level of the Amphibians,
together with Laccrtians, and also swimming Saurians, species belong¬
ing to the inferior divisions of True Reptiles.
Vertebrates commenced, not with the lowest fishes, but with a
group above the true level of the fish, in a type which included
several characteristics of the higher class of Reptiles (p. 302).
The evidence in the rocks thus sustains the conclusion that many
of the groups began, not with their lowest species,—that is, those at
the bottom of the lower group,—but, on the contrary, with those at
the top of the lower group and near the bottom of a higher, or from
some intermediate point between the two. In this way a remarkable
harmony was given to the fauna and flora of an age. The flora of
the Carboniferous is a fine example of this principle.
This harmony was sometimes further promoted by adding to one
GENERAL OBSERVATIONS.
397
type peculiarities of another, where this intermediate position of
the species is not apparent. Thus, in the age of Mollusks, perhaps
the most abundant form of Crustacean was the Ostracoid, which
had a bivalve shell like the Mollusks.
None of the examples of comprehensive or undivided types have been drawn
from Mollusks. They are, in fact, less marked in this sub-kingdom, because all
its several grand divisions were represented in the first appearance of animal
life, even to the highest, that of Cephalopods. It started as an unfolded type.
There were even many of the minor subdivisions in the early Silurian. The
siphonated Conchifers—the higher group—commenced with the Potsdam period
(p. 191), if the genus Conocardiuin is rightly referred to the Cardium family;
Pteropods probably passed their period of culmination in the Silurian; Brachio-
pods, theirs, in the later Palmozoic; and Cephalopods, theirs, in the Mesozoic.
Gasteropods were less well represented than the other tribes, and these have
their fullest display in the present age. The Cephalopods, however, may
properly rank among comprehensive types; they combine in the Molluscan
structure the large perfect eyes and other senses of the Vertebrates, and in
some of them an internal bone, along with great activity and strength,—cha¬
racteristics not typical of Mollusks. They were the princes of the Palrno-
zoic world until the appearance of Vertebrates, — the tj7pe they partly fore¬
shadowed.
(4.) The comprehensive types of early time become nearly or quite
extinct with the progress of the system of life, while the types which
were foreshadowed by them or partly comprehended in them are
long afterwards perpetuated.
Trilobites, Lepidodendrids, Sigillarids, Calamites, become extinct
in the Carboniferous age, Cystideans in the Lower Devonian. It
will be found that the Ganoid fishes and Labyrinthodonts are also
examples under this law. The small Lycopodia of our woods
are the only representatives of the great Lepidodendrids of the
Coal era, while ferns, the typical Acrogens, and Conifers, the typi¬
cal Gymnosperms, are yet abundant in species. The Trilobites
were accompanied by typical Entomostracans, the Eurypteri and
related species, before the close of the Silurian; and, when disap¬
pearing in the Carboniferous age, the Tetradecapods, foreshadowed
in the Trilobites, were already in the waters.
2. Exterminations.—At the close of each period of the Palaeozoic
ages there was a general extermination of the living species, which
was nearly, and sometimes quite, complete. Again, as each epoch
terminated there was an extermination of life, but in most cases
much less general. With the transitions between strata of different
kinds in the course of an epoch there were usually some extermi¬
nations; and even in the passage from layer to layer the extinction
of one or more species took place. In a corresponding manner
398
PALAEOZOIC TIME.
there were often one or more new species with each new kind of
layer, and generally several with each change in the strata; while
many appeared with the opening of an epoch, and a whole fauna,
nearly, with the commencement of a period. There is, then, this
grand principle:—
Creations ancl extinctions of species were going on through the
whole course of the history, instead of being confined to particular
points of time; but at the close of long periods and epochs there
were nearly universal extinctions, followed by abundant creations.
The means by which exterminations may have been produced
have been often alluded to in the preceding pages, and need here
be recapitulated only in brief,—namely:
For marine species, (1) a sinking of the sea-bottom, carrying the
species below the depth at which they flourish; or (2) an elevation
of it so as to make it dry land, on which, of course, all the marine
life would become extinct; (3) a change by variation of level or
raising of barriers sufficient to change clear and pure waters into
waters full of sediment, or expose them to an influx of sedimentary
material, and the reverse ; (4) a similar change, sufficient to turn the
salt-water sea into a fresh-water area. Besides these, there may be
mentioned submarine igneous action heating the waters. With
such causes for exterminations, it is intelligible that the extinction
of a fauna might be nearly complete in one area and not so in
another, and that where such extinctions were partial there might be
in some cases a partial repeopling of a district from that one in
which there were surviving species.
3. Extinction of whole tribes, families, or genera of species.—The charac¬
teristic tribes of land-plants in the Coal era, and those that became
extinct, have been mentioned on p. 333.
The races of animals that were most prominent in giving a spe¬
cial character to the Palaeozoic fauna were as follow :—
Among Radiates, Crinoids and Cyathophylloid Corals; among
Mottusks, Brachiopods ; among Articulates, Trilobites ; among Verte¬
brates, the vertebrate-tailed Ganoid fishes. Of these, the groups
of Cyathophylloid Corals and Trilobites become extinct with the
close of the Palaeozoic, and the vertebrate-tailed Ganoids very
nearly so ; and Crinoids and Brachiopods lose their pre-eminence
in numbers of species and individuals in their respective sub-
kingdoms.
The following are a few other examples of the extinction of pro¬
minent Palaeozoic groups:—
Graptolites, which culminated in the Lower Silurian and ended in
the Clinton epoch of the Upper Silurian ; Cystideans, which culmi-
GENERAL OBSERVATIONS.
399
nated also in the Lower Silurian and became extinct in the begin¬
ning of the Devonian; Goniatites, which began in the Hamilton
period of the Devonian and disappeared with the Carboniferous
age. Many other instances are given in the table beyond. The
causes of such extinctions w7ere connected with a higher principle
than that of mere physical catastrophe.
The following table presents to the eye the history of many of the
genera, families, and tribes of Palaeozoic species, showing by means
of the narrow dark areas the time of their commencement; the
time of their culmination (by the greatest breadth of the area);
and the time of their extinction in the course of the Palaeozoic
ages, or the fact of their continuing to survive in after-time. Thus,
opposite the word Polyps, the area commences near the beginning
of the Silurian, and increases through the Palaeozoic, and does not
terminate there, as they exist afterwards; the Cyathophylloid Corals
begin with the Lower Silurian, have their maximum in the Devo¬
nian, and terminate in the Carboniferous ; the Astrcea, Madrepora,
and Caryophyllia families of corals (which include most modern reef-
making species) do not commence until after the Palaeozoic, and
hence, as there are no Palaeozoic species, there is a dotted line op¬
posite, without an area. At the top of the columns, P. Pd. stands
for Potsdam or Primordial Period ; and S., C., P., for Subcarboni-
ferous, Carboniferous, and Permian.
4. Genera of the present time dating from the Palceozoic age.—The num¬
ber of lines connecting the past with the present is considerably
increased in the Carboniferous age. These lines are, however, only
long-lived genera, not species. The following are those which
appear to be determined with a good degree of certainty:—
Lingula, Piscina, Crania, Nautilus, Pleurotomaria, Rhynchonella, Terc-
Iratula, Ostrea, Avicula, Pinna, Pecten, Solemya, Leda, Nucula, Dcnta-
lium, Chiton. They are all Molluscan. The first five commenced in
the Lower Silurian. It is a remarkable fact that there are no Ra¬
diate genera in this list.
Besides the above, the genera Area, Lima, and Astarte have been
referred to the Palaeozoic ; but the species probably belong to other
genera. There are no genera of Articulates, unless it be the genus
Spirorhis, about which there is doubt. Some of the Palaeozoic genera
of Ostracoids have modern names, but there are no means of prov¬
ing that they are identical in type with those of modern seas.
There are modern genera of Ehizopods in the Palaeozoic, and pro¬
bably also of Diatoms ; and the number of such genera among these
protozoan and protophyte forms will probably be greatly increased
when further investigated.
400
PALAEOZOIC TIME.
RADIATES.
Polyps
Cyathophyllum Family.
Favositos (Acalepbs?)
Halysites (Acalepbs?)
Astraaa, Madrepora, and Caryophyllia
Families
Acalephs
Graptolites
Chsetetes
Echinoderms
Cystideans
Crinideans
Blastoids (Pentremites, etc.)
Star-fishes
Palaeechinoids (including Arcba>ocidaris)
Cidarids, Spatangids, etc
MOLLUSKS.
Brachiopods
Lingula Family, gen. Lingula
Obolus, Obolella
Discina Family, gen. Discina
Siphonotreta
Orthis Family, gen. Orthis
Strophomena
Rhynchonella Fam. gen.Rliynchonella,etc
Pentamerus
Camarophoria
Productus Family, gen. Chonetes
Productus
Spirifer Family, gen. Atrypa
Spirifer
GENERAL OBSERVATIONS.
401
Terebratula Family, gen. Terebratula.
Stringoceplialus, Rensselaeria
Other Terebratulids.
Crania Family, gen. Crania.
Calceola Family, gen. Calceola
Bryozoans
Acephals
concihfers
Monomyaries .
Dimyaries without a siphon.
Dimyaries having a siphon...
Cephalates
Pteropods
Gasteropods
Shell without a beak.
Shell beaked.
Cephalopods
Nautilus tribe, includingOrthoceras, etc.
Ammonite tribe, gen.Gouiatites
ARTICULATES.
Worms
Crustaceans
Entomostracans..
Ostracoids.
Trilobites...
Paradoxides, Conocephalus, Sao,
Ellipsoeephalus, Hydrocepha¬
lus, Dicelloceplialus, Arionel-
lus, Meuocepllalus
Bathijurus Olenus, Agnostus
Ogygia
Trinucleus, Asaphus, Remopleu-
rides,Ainphion,and Triarthrus
Calymene, Ampyx, Illaenus,
27 Acidaspis, and Cheirurus
402
PALEOZOIC TIME.
Homalonotus and Lichas
Phillipsiar Griffithides
Phyllopods
Cyclops Tribe (Eurypterus, etc.)
Tetradecapods
Isopods
Amphipods
Decapods
Schizopods)
Macrourans and Anomourans
Brachyurans
Myriapods
Spiders: Scorpions
Insects
Neuropters, Orthopters
Beetles
Lepidopters, Dipters, Hymenopters, etc.
VERTEBRATES,
fishes
Ganoids
Selachians
Cestracionts
Hybodonts
Reptiles
Amphibians
Ordinary
Labryinthodonts
True Reptiles
Lacertians
Enaliosaurs
Crocodilians
Birds: Mammals
SILURIAN.
CARB.
i j
GENERAL OBSERVATIONS.
403
5. Complete extermination of the Carboniferous life.— At the close
of the Carboniferous age there was a complete extermination of all
living species. No plant or animal of America continues from the
Carboniferous into the Reptilian age; and the same is probably
true for Europe.
DISTURBANCES CLOSING PALAEOZOIC TIME.
1. AMERICAN.
After the long ages of comparative quiet, when the successive
Paheozoic formations were in slow progress, and finally the rock-
foundation of the continent east of the Rocky Mountains was nearly
completed, a change of great magnitude began, which involved the
Appalachian region with the continental border adjoining, and well
merits the title of the Appalachian revolution.
The evidences of the change may be treated of under two heads:—
1, disturbances of the strata; 2, alteration or metamorphism, due,
partly at least, to heat.
1. Disturbances of the strata.
1. Flexures.—The Coal measures of Pennsylvania, Rhode Island,
and Nova Scotia, which were originally spread out in horizontal
beds of great extent, are now tilted at various angles, or rise into
folds, and the strata are broken and faulted on a grand scale. The
folds vary from a few rods to one hundred or more miles in breadth,
and are in many successions over the region, wave succeeding wave.
Moreover, not only the Coal measures, but the Devonian and Silu¬
rian, and in some regions, at least, part of the Azoic beds beneath,
are involved together in this majestic system of displacements.
The following facts on this subject are mainly from the Memoirs
and Geological Reports of the Professors Rogers.
Fig. 619.
d^^^^TT///^VTtn
ilfl
$
1
\
.
The general character of the flexures is illustrated in the annexed
sections. Fig. 619 (by Taylor) is from the anthracite strata of the
404
PALEOZOIC TIME.
Mauch Chunk region, Pennsylvania. The great coal bed is folded
and doubled on itself, and part of the enclosing strata are nearly
vertical. In fig. 620 (by Rogers), from Trevorton, Pa., the folding
is of a more gentle kind; eight coal seams are contained in this
Fig. 620.
section, each of the dark lines representing one. These are exam¬
ples of the condition of the whole anthracite region. The patches
into which it is divided, as shown on the map, p. 323, illustrate
other effects of the foldings; for the whole, in all probability, was
originally one great area, continuous with that of western Penn¬
sylvania.
The sections represented in figs. 621, 622, illustrate the flexures
of the Palaeozoic rocks, showing that the whole participated in
Fig. 621.
Section on the Schuylkill, Pa.; P. Pottsville, on the Coal measures.
the system. Fig. 621 (by Lesley) is a section from the Schuyl¬
kill along by Pottsville: the formations included in it embrace
Fig. 622.
-t—'.r^r^TK.t
S.E.
YIV IV
in n in
iv v vi vviriv m k
Section from the Great North to the Little North Mountain through Bore Springs, Va.; I, t,
position of thermal springs.
from the Potsdam sandstone (2) to the Coal formation (14); the
numbers indicate the formations. The section in fig. 622 (by
Rogers) extends from the Great North to the Little North Moun¬
tain through the Bore Springs, in Virginia: it has been partly ex-
GENERAL OBSERVATIONS.
405
plained on pp. 104, 107. The formations are numbered—II. the
Calciferous; III. Trenton; IV. Hudson River; V. Oneida; VI.
Clinton and Lower Helderberg; VII. Oriskany sandstone and
Cauda-Galli grit.
The mountains of Pennsylvania as well as Virginia are full of
such sections. In fact, they present the common features of the
Appalachians from Alabama to New Jersey. It is here obvious
that not only the Coal measures but the whole Palaeozoic has been
forced by some agency out of its originally horizontal condition into
this contorted state. The folds were mountains themselves in ex¬
tent ; but through the extensive denudation to which they have
since been subjected they have been worn off and variously modified
in external shape, until now, as explained on page 108, it is often
extremely difficult to trace out the original connections.
On the east, or towards the ocean, the folds are so pressed toge¬
ther, and their tops so completely removed, that often only a series
of southeasterly dips remain (p. 107). Beyond these, the folds are
more separated, though still abrupt; farther west, they diminish
in boldness, until they become gentle undulations ; yet there is
often a sudden transition to these gentler bendings along lines of
great faults. The following outline represents this general feature
of the successive folds from the southeast or ocean side across the
mountains to the northwest. (Rogers.) It should not be inferred
from this figure that the folds have the regularity here given; the
preceding figures show that this is very far from the truth. It
would also be an error to suppose that the number of folds is uni¬
form through the length of the Appalachians. On the contrary,
all along their course there are folds rising and others disappearing;
Fig. 623.
^ nvwT
Ideal section from the s.e. to the n.W. across the Appalachians.
they may continue on for a few miles or scores of miles, and some
for much greater distances, and then gradually disappear, while
others, more to the east or west, take their places. Thus, the Ap¬
palachian chain is made up of a complexity of flexures following a
common direction. This character is well shown in fig. 624,—a
map prepared for this work by J. P. Lesley, wrho, in connection
with other assistants in the Geological Survey of Pennsylvania, has
done much towards working out the facts here presented. It gives
a general view of the direction and number of the folds through
Pennsylvania. Each line stands for the axis of a flexure. Without
406
PALAEOZOIC TIME.
claiming absolute accuracy, it gives a correct general idea of the
number and positions of the folds in this part of the Appalachian
region.
Fig. 624.
The following are some of the most important facts established
with regard to these Appalachian flexures:—
1. They occupy the whole Appalachian and Eastern-border regions of
the continent nearly or quite to the Atlantic Ocean.
2. They are parallel with the general course of the mountains,
and nearly with the Atlantic coast.
3. They are most crowded and most abrupt over the part of the
regions which is towards the ocean,—that is, the southeast side
(figs. G22, G23).
4. The steepest slope of a fold is that which faces the northwest,
or away from the ocean (figs. G21-G23).
GENERAL OBSERVATIONS.
407
5. They are in numerous ranges; but, while some are of very
great length, there is in general a commingling of shorter flexures,
and often they are in groups of overlapping lines (fig. 624), as
explained, with reference to the arrangement of the parts of
mountains, on pp. 19 and 20.
6. Although many of the folds were like mountains in dimen¬
sions, they have been so worn and removed by denuding waters—
either those of the ocean or rivers, or of both—that the higher parts
of the folds do not generally form the summits of existing eleva¬
tions. The fissures of the broken mountains would have been
deepest and most numerous in the axes of the folds ; and hence de¬
nudation has been most destructive along the more elevated por¬
tions.
7. Over the more eastern part of the Appalachian region and the
Continental border the folds were generally so pressed over to the
northwest that their tops projected westward, and, consequently,
both the southeast and northwest sides have a common dip to the
southeast (fig. 623); and, as these regions have been since denuded,
nothing remains in many parts but a series of strata dipping all
alike to the southeast. (See p. 107.)
A uniform series of southeast dips over such a region is evidence
that the strata correspond to a number of decapitated folds.
2. Faults.—Besides the remarkable plication of the earth's crust
in this Appalachian revolution, numberless fractures and faults or
dislocations occurred over the whole region, as was natural under
the contortions and uplifts in progress. Some of the faultings were
of great extent, lifting the rocks on one side of the line of fracture
5000 or 10,000 feet above the level on the other side. The faults
mentioned on p. 198 are of this character, and part of the series
there alluded to was probably made at this time. There is one of
these great faults west of the Cumberland Mountains, in eastern
Tennessee, well shown in the map and sections by Safford. In
southwestern Virginia there are faults, according to Rogers, of seven
or eight thousand feet. One remarkable line of this kind extends
along the western margin of the Great Valley of Virginia, through¬
out the chief part of its length, along by the ridge (on the north¬
west side of the valley) named in its different parts the Little North
Mountain, North Mountain, and Brushy Ridge. In some parts the
Lower Silurian limestone is brought into conjunction with beds but
little below the Subcarboniferous limestone, so that there is a tran¬
sition from the lower strata to the upper in simply crossing the
fault. In some places there is an inversion of the strata, so that
a bed of semibituminous coal of the upper beds is found under the
408
PALjEGZOIC TIME.
Lower Silurian limestone and conformable to it in dip. This fault
continues on for eighty miles. (W. B. & II. D. Rogers.)
Several such examples might be cited from Pennsylvania as well
as Virginia. One occurs near Chambersburg, Pa., and is thus
described by Lesley in his " Manual of Coal and its Topography"
(p. 147). "The western side of the anticlinal Cove canoe has been
cut off and carried down at least twenty thousand feet into the
abyss, along a fracture twenty miles in length; the eastern side
must have stood high enough in the air to make a Hindoo Koosh ;
and all the materials must have been swept into the Atlantic by
the denuding flood. The evidence of this is of the simplest order
and patent to every eye. The highest portions of the Upper Silu¬
rian wall against the lowest portions of the Lower Silurian. The
thickness of the rocks between is, of course, the exact measure of
the downthrow, which is therefore twenty times as great as the
celebrated Pennine Fault in England. Yet a man can stand astride
across the crevice, with one foot on Trenton limestone and the
other on Hamilton slates, and put his hand upon some great frag¬
ments of Shawangunk grit, caught as it was falling down the
chasm, held fast in its jaws as it closed, and revealed by the merest
accident of lying suspended in the crack just where the plane of
denudation happened to cut it."
Passing now farther north, to Hew England, we find the same
system of flexures as occurs to the south. The rocks are generally
crystalline, and it is not at first obvious that they were ever Palaeo¬
zoic strata and have been metamorphosed into their present con¬
dition. But this is proved by the portions of the strata which
remain undisguised by the alteration.
The western part and summit of the Green Mountains have
already been shown to be altered Lower Silurian, and fossils have
been referred to that prove it (p. 392).
Again, Devonian (Upper Helderberg) rocks ha\^ been identified
by their fossils in northern Vermont and at Bernardston in Massa¬
chusetts. It is probable that from the former position a line of
Devonian rocks extends south through eastern Vermont; and the
Bernardston beds are supposed to be part of the same formation,
but on the opposite side of an anticlinal. (Hitchcock.)
Between Worcester, Mass., and Newport, R.I., the Coal forma¬
tion occurs with its usual fossil plants, and conglomerates of the
Coal measures stretch on towards Boston (p. 325).
South of Boston, at Braintree, fossils of the Potsdam period
have been found (p. 184). On the northern margin of New Eng¬
land the rocks graduate into those of British America, which are
GENERAL OBSERVATIONS.
409
hardly at all altered, and which are Silurian, Devonian, and Car¬
boniferous in age.
There is, therefore, abundant reason for the inference that New
England is made up of Palaeozoic rocks. The White Mountains of
New Hampshire are now believed to be formed of altered Devo¬
nian strata. The gneiss quarries of Haddam, on the Connecticut,
probably consist either of Carboniferous or Upper Devonian depo¬
sits ; for the graphite on the slabs sometimes has the form of the
stems of plants: one of them, fourteen inches long and one to two
wide, now in the Yale cabinet, is too plainly vegetable to be
doubted, though now deprived of its original markings.
The conformity to the Appalachian system appears in,—
1. A general parallelism of the outcrops to the Green Mountains,
the bands of rock marked on a geological map all having this
common course.
2. A general prevalence of east-southeast dips over New Eng¬
land, showing that there are here a series of decapitated folds, as
well as over eastern Pennsylvania and Virginia.
3. The steepest side of the fold being the western, as follows
from the fact last mentioned.
4. The flexures, fractures, and dislocations of the coal beds of
Rhode Island and the neighboring region in Massachusetts.
Western New England received a part at least of its flexures
before the Upper Silurian era (p. 392). The rest probably dates
its upturning from the time of disturbance here considered. The
fact that the Coal formation is among the folds proves this for a
large part of New England. Between these beds and the Devo¬
nian of eastern Vermont the rocks are probably either Carboni¬
ferous or Devonian ; and the whole probably participated in these
changes.
In Nova Scotia and New Brunswick there are other examples of
folded Carboniferous, Devonian, and Silurian strata, sustaining the
conclusions deduced from the regions to the southwest.
Thus, the whole Continental border from Alabama to Newfound¬
land participated in these grand movements. The facts mentioned
do not prove that the production of the flexures in the strata was
necessarily accompanied by the emergence of the Appalachian
region.
2. Alterations of rocks.
The alterations which the rocks underwent at the time of these
disturbances are as follow :—
1. Consolidation.—Strata were consolidated ; for the rocks of the
410
PALAEOZOIC TIME.
Coal measures, the conglomerates and sandstones especially, are
often very hard and siliceous where the beds have been most folded
or disturbed.
2. Dehituminization of Coal.—The coal is without bitumen or a true
anthracite where the rocks are most disturbed; and going west¬
ward, into regions of less disturbance, the proportion of bitumen or
volatile substances increases quite regularly (Rogers). It appears
as if the dehituminization of the coal had taken place from some
cause connected with the uplifting. In Rhode Island the effects
are still more marked, the coal being altered not simply to an
excessively hard anthracite, but in part to graphite.
3. Crystallization or metamorphism.—In the regions where the folds
are pressed together most crowdedly and the evidences of disturb¬
ance are extreme, as over New England, and the Eastern border
south of New York, the rocks are often crystallized, being granite,
gneiss, mica schist, and the like. There, also, granitic and mineral
veins abound.
3. Some characteristics of the force engaged.
The cause of this extensive series of flexures had, obviously, the
following among its characteristics:—
1. The force acted, at right angles to the course of the flexures, and, there¬
fore, to the general direction of the Atlantic coast.—It is obvious, without
explanation, that only force from this direction could have pro¬
duced the result. The process is easily imitated with paper or
cloth.
2. The force acted from the direction of the ocean.—For all the effects—
the flexing and metamorphic—are most intense on the oceanic
side ; they fade out towards the interior.
3. The force was vast in amount.
If any one doubt, he may satisfy himself by working out the following
problem :—
(«.) Given the thickness of the rocks at 30,000 to 40,000 feet (the depth
of the Palaeozoic in the Appalachians), part of the beds (if not all) already
stiff and solid,—for the limestones are as solid when first formed as ever after¬
ward. (It is probable that the whole earth's crust was involved, giving a
thickness of 100,000 feet or more.)
(b.) Length of region acted upon, 1500 miles; breadth, 100 to 300 miles.
(c.) Required to press the beds, over this region, from top to bottom, into a
series of great flexures such as has been described, and to force them on to the
northwest until the tops of many of the flexures shall overhang their bases to
the westward, and farther until numbers of them shall close up into a solid
body or mass : span of flexures, mostly from 1 mile to 50: rise, mostly from 100
to 5000 feet.
GENERAL OBSERVATIONS.
411
Whoever tries to work the problem will emerge from his calculation satisfied
that the force was vast.
4. The force ivas slow in action and long continued.—That the move¬
ment must have been slow in progress, the flexures forming by a
movement of a few feet or yards in a century, continued through a
long time, is evident from the regularity of the stratification not¬
withstanding the majestic system of foldings; for there is no chaos:
the beds remain in their old order, only bent into arches and bold
flexures. The brittle rock experienced the force so gradually that
it yielded with little fracture, except along the axes of the folds,
where the strain was greatest. The folds were sometimes pressed
over until their tops projected westward over their bases,—which
could have been done only by a force acting with extreme slow¬
ness. There may have been sudden starts, and earthquakes be¬
yond modern experience, but the general course of progress must
have been quiet.
5. Heat.—Several thermal springs exist in Virginia, situated, ac¬
cording to Rogers, along the axes of the Appalachian folds, as if
some traces of the heat in action still remained.
4. Identity of the force with that causing movements in
earlier time.
The force was the same in kind, and also in direction, judging
from the identity of results, with that which produced the flexures
and other changes that closed the Azoic age (p. 143); the same that
caused the oscillations through the progressing Palaeozoic ages re¬
quired for the completion of the succession of rocks ; the same
that occasioned the deep subsidences along the Appalachian region.
The Atlantic coast along New England varies much from its
general course. But this is only a repetition of an Azoic fact. The
line has a parallel in the Green Mountains with the westward bend
through New Jersey and Pennsylvania, and a still earlier parallel
in the outline of the New York Azoic.
When the Appalachian subsidences were about to cease, then
began the new movement that flexed and stiffened the rocks of
the Atlantic border.
Although there is no proof in the flexures, or the metamorphism,
of any emergence of the strata from the ocean during their pro¬
gress, there is sure evidence that when the revolution ceased it left
the Appalachian chain with at least its present elevation. The
evidence of this final result of the moving forces is afforded by the
strata of Mesozoic time, which come next under consideration.
412
PALAEOZOIC TIME.
2. DISTURBANCES IN FOREIGN COUNTRIES.
The disturbances through the course of the Palaeozoic ages in
Europe appear to have been more numerous and diversified than
in America. But they were inferior in extent to those that
attended its close. Murchison remarks that the close of the Car¬
boniferous period was specially marked by disturbances and up-
liftings. He states that it was then " that the Coal strata and
their antecedent formations were very generally broken up and
thrown, by grand upheavals, into separate basins, which were frac¬
tured by numberless powerful dislocations." In the north of
England, as first shown by Sedgwick, and also near Bristol, and in
the southeastern part of the Coal measures of South Wales, there
is distinct unconformability between the Carboniferous and lowest
Permian. Elie de Beaumont has named this system of dislocations
the System of the North of England. Between Derby and the frontier
of Scotland the mountain-axis is of this date, and trends between
north and north-northwest; the region is remarkable for its im¬
mense faults. The great dislocations of North Wales may be of the
same epoch.
Yet, while it is manifest that the period between the close of the
Carboniferous and the Trias was one of enormous disturbances, it
is not always clear to what time in this interval particular uplifts
should be referred. In the Dudley coal field, the Permian beds,
according to Murchison, are conformable to the Carboniferous;
but at the close of the Permian (or at least before the middle
of the Trias) there were great dislocations. In other coal regions,
as those of France and Belgium, and of Bohemia about Prague,
there is other evidence of physical changes in the absence of Per¬
mian beds, while also, in many places, the beds of these coal
regions are much contorted. De Beaumont's System of the Nether¬
lands includes dislocations of Permian beds along the foot of the
Hartz Mountains, and in Nassau and Saxony, which preceded
the deposition of the Triassic. He distinguishes examples of this
system of disturbances in France and some other parts of Europe,
and also prominently in South Wales. To his System of the Rhine
he refers dislocations and elevations of the Permian sandstone of
the Vosges (gres de Yosges) along the mountains of the Yosges,
the Black Forest, and the Odenwald, and shows that they antedate
the Triassic period.
In Russia, as well as England, there are tracts where the Per¬
mian strata follow on after the Carboniferous without unconforma¬
bility. It was in this closing part of the Pakeozoic era, either
PALAEOZOIC TIME.
413
after the Carboniferous or Permian, that the rocks of the Urals
were folded and crystallized; for Carboniferous rocks are flexed
and altered in the same manner as in the Appalachians. The
auriferous quartz veins probably date from this era.
TRANSITION FROM THE PALiEOZOIC TO TIIE MESOZOIC.
The transition from Paleeozoic to Mesozoic time was strongly
marked in Geological history,—unequalled, in fact, by any of earlier
date after the Azoic revolution in which the Laurentian rocks were
folded and crystallized, and by any in later ages, with the single
exception of that from Mesozoic to Cenozoic time. The events
which give it this prominence are :—
1. A thoroughly complete extermination of existing life.
2. An extinction of several great Palaeozoic races, the decline of
others, and a general change in the character of the life.
3. The extensive folding and crystallizing of Palaeozoic formations
in many regions.
4. The development of a number of prominent mountain-ranges,
making new features in the earth's topography.
5. In North America, a great change in the scene of geological
progress, so that the regions are no longer the Eastern border, the
Appalachian, and the great Interior Continental; but, instead, the
Atlantic border, the Gulf border, and the Western Interior, or interior
west of the Mississippi. The Eastern Interior and the Appalachian
regions no longer participate in the rock-making. The three new
regions coalesce; the last is but a continuation of the Gulf region
to the northwest over the area of the Rocky Mountains, which was
still low or submerged; whether it communicated directly with the
Pacific is not ascertained.
By the close of the Palaeozoic, nine-tenths of all the rocks of the
globe had been formed. During the epoch of revolution that fol¬
lowed, these beds, besides undergoing in many regions an exten¬
sive crystallization fitting them prospectively for the uses of art,
were also supplied with mineral wealth. Much of the gold of
the world comes originally from rocks which were metamor¬
phosed and filled with veins at this time. The same is believed to
be true of platinum and diamonds. None of the precious metals
are yet known to occur in the crystalline Azoic. Some of the veins
of tin, copper, and lead, and mines of topaz, emerald, and sapphire,
are among the productions of this epoch of metamorphism.
Thus furnished, the world was prepared for another stage in its
course of progress.
414
MESOZOIC TIME—REPTILIAN AGE.
III. MESOZOIC TIME.
The Mesozoic or Medieval time in the Earth's history comprises
a single age only,—the Reptilian.
REPTILIAN AGE.
The Age of Reptiles is especially remarkable as the era of the
culmination and incipient decline of two great types in the Animal
Kingdom, the Reptilian and Molluscan, and of one in the Vegetable
Kingdom, the Ci/cadean. It is also remarkable as the era of the
first Mammals,—the first Birds,—the first of the Common or Osseous
Fishes,—and the first Palms and Angiosperms (p. 166).
The Age is divided into three periods. Beginning with the ear¬
liest, they are:—
1. The Triassic Period.
2. The Jurassic Period.
3. The Cretaceous or Chalk Period.
These periods are well defined in European Geology. But in
North American the separation of the first and second has not yet
in all regions been clearly made out.
TRIASSIC PERIOD (16).
The name Triassic, given to this period, alludes to a threefold
division which this formation presents in Germany. This division
is a local character, and unessential: it does not occur in other
remote parts of Europe, or in England, and is not to be looked for
in distant continents.
1. AMERICAN.
The formation referred to the Triassic in America may belong
in part to the Jurassic period. It does not reach back into the
Permian, because there are no Palaeozoic forms among the plants
or animals. It is also true that there are no species that are pecu¬
liarly Jurassic, while many of them correspond in character with
those of the foreign Triassic.
I. Rocks : kinds and distribution.
The rocks are met with in two distinct regions:—1, in the Atlantic
border region, between the Appalachians and the coast; 2, in the
Western Interior region, over part of the slopes of the Rocky Mountains.
On the Atlantic border the beds occur in long narrow strips
TRIASSIC PERIOD.
415
parallel with the mountains or the coast-line, and occupy synclinal
valleys formed in the course of the folding of the Appalachians.
They lie unconformably on the folded crystalline rocks, and thus
show that they are subsequent in age. On the map, page 133, the
narrow areas are obliquely lined from the right to the left. One is
situated in the Connecticut valley, and extends from New Ilaven
to northern Massachusetts; others are distributed over the region
between the lower Hudson (the Palisades) and the southern part
of North Carolina.
The map of Pennsylvania on p. 323 shows the position of the
area in that State, it being distinguished by the same oblique lining
as on the general map. It takes the same westward bend with the
Appalachians of the State, retaining that parallelism with the
mountains which characterizes the areas elsewhere, and thus cor¬
responding in direction with the synclinal valleys.
The rock is in general a red sandstone, passing in some places
into a shale or conglomerate, and occasionally including beds of
impure limestone. The brown building-stone of Newark, N..J.,
and Portland, Conn., often called Freestone, and much used in the
city of New York ancl elsewhere, comes from this formation. Near
Richmond, Va., and Deep River, in North Carolina, there are valu¬
able beds of bituminous coal.
In many regions the layers of rock are covered with ripple-
marks and raindrop-impressions, or penetrated with what were ori¬
ginally mud-cracks,—all of which marks are evidences of exposure
above the water during the progress of the beds.
In the Connecticut valley, and to some extent also in New Jersey
and Pennsylvania, the surface of the beds is sometimes marked with
the footprints of various animals, as Insects, Reptiles, and Birds;
and Professor Hitchcock, who has made the tracks of the Connec¬
ticut valley his special study, has in the Amherst College Cabinet
(at Amherst, Mass.) about 8000 tracks, averaging sixty-eight tracks
for each species of animal. There are also numerous specimens in
other collections in New England and elsewhere.
On the Gulf border there are no Triassic rocks, excepting such as
may possibly be buried beneath later formations.
The formation beyond the Mississippi which is supposed to be
Triassic consists of sandstones and marls of usually a brick-red
color, and often contains gypsum. It outcrops at the base of the
ridges of the Rocky Mountains, and covers wide areas. It is
largely developed west of the summit in the Colorado valley, espe¬
cially about the region of the Little Colorado.
(a.) Atlantic border.—The areas on the Atlantic border are as follow:—
416
MESOZOIC TIME REPTILIAN AGE.
1. The Acadian.—(1.) A region in Nova Scotia, forming the east side of the
Bay of Fundy, and reaching eastward in this line, though with some interrup¬
tions by water, to the eastern borders of the Basin of Mines. (2.) Prince
Edward's Island, which is covered throughout with it.
2. The Connecticut River range.—Extends along the Connecticut valley, from
New Haven, on Long Island Sound, to the northern limits of Massachusetts,—
a distance of one hundred and ten miles: the average width is twenty miles.
3. The Southbury range.—A small parallel region in Connecticut, more to the
westward, in the towns of Southbury and Woodbury.
4. The Palisade range.—This is the longest continuous line,—'being about
three hundred and fifty miles in length. It extends from Rockland on the
Hudson River, southwest, through New Jersey, Pennsylvania, and Virginia, east
of the Blue Ridge, being thirty miles wide in some places in New Jersey,
twelve on the Susquehanna, and six to eight on the Potomac. It crosses the
Delaware between Trenton and Kintnerville, the Susquehanna at Bainbridge,
and the Schuylkill twelve miles below Reading. The map (p. 323) gives the
position of the beds in Pennsylvania, indicated by oblique lines.
5 and 6.—Short ranges in Virginia, parallel to the last, and more to the east¬
ward. The easternmost, or Richmond range, commences on the Potomac, a few
miles below Washington, and continues to Richmond and twenty-five or thirty
miles beyond. The other lies twenty-five miles west of the Richmond range.
7. The North Carolina range.—It begins near Oxford, in Granville eo., and
follows nearly the line of the Richmond range (of Virginia), crossing Orange
and Chatham cos. westward of Raleigh, passing Deep River, where it contains
coal, and extending into South Carolina. It is one hundred and twenty miles
long; on the Neuse it is twelve miles broad, between Raleigh and Chapel Hill
eighteen miles; on the Cape Fear, not over eight miles.
As the several regions are isolated from one another, they naturally differ
widely in the succession of beds and in the character of the rocks. They can¬
not, therefore, be brought into parallelism by reference to mineral characters.
In the Connecticut River region, in Massachusetts, according to Hitchcock,
these beds consist, beginning below, of—
1. Thick-bedded sandstone through nearly half the thickness, in some parts
a conglomerate.
2. Micaceous sandstone and shale, with fine-grained sandstone. This shale
sometimes contains coal seams and fossil fishes.
3. A coarse gray conglomerate, the masses sometimes several feet through.
The material has come from the crystalline rocks adjoining,—the granite,
gneiss, mica schist, talcose schist, etc. The thickness has not been satisfactorily
ascertained : it cannot be less than 3000 feet, and may be more than double this.
At Southbury, Ct., and near Springfield, Mass., there is an impure gray or
yellowish limestone fitted for making hydraulic lime.
In Virginia, they consist, as in New England, of the debris of the older crys¬
talline rocks with which they are associated. Near Richmond, where the beds
are 800 feet thick, there are 20 to 40 feet of bituminous coal in three or four
seams alternating with shale, and in some places the coal shales are directly in
contact with the subjacent granite and gneiss. The coal is of good quality, and
resembles the bituminous coal of the Carboniferous era. It contains, according to
TRIASSIC PERIOD.
417
Hubbard (Amer. Jour. Sci. 1842, xlii. 371), 30 to 35 per cent, of volatile
ingredients.
In North Carolina, the beds rest on the crystalline rocks, and have been derived
from their wear. Emmons divides them into three groups, beginning below :—
1. The Lower red sandstone and its underlying conglomerate, estimated at
1500 to 2000 feet in thickness.
2. The Coal measures, including shales and drab-colored ripple-marked sand¬
stones, in some places 1200 feet thick.
3. The Upper red or mottled sandstones and marls, separated at times from
the bed below by a conglomerate.
There are five seams of coal at the Deep River Mines,—the first (or upper),
and best, 6} feet thick. The coal resembles that of Richmond, and is valuable
for fuel. Emmons obtained 28 to 31 per cent, of volatile ingredients. The
">eds below the coal are of much less thickness in the Dan River coal region
than in that of Deep River. Good argillaceous iron-ore abounds in the coal
region of North Carolina, so that in almost every respect there is a close re¬
semblance to the coal regions of older date. Both at Richmond and in North
Carolina there are numerous coal plants in the beds, and many stems or
trunks stand as they grew, penetrating the successive layers.
(6.) Western Interior region.—There is still some doubt as to the age of the
beds of the Rocky Mountains referred to the Triassic period. Although very
widely distributed, they seldom contain fossils; and the few found—an occa¬
sional piece of fossil wood and remains of Saurians—are not sufficient to settle
the question. The beds of the eastern slope are known to underlie unques¬
tionable Jurassic beds at the Black Ilills in Dakota and the Red Buttes
on the North Platte, and hence to occupy a position between the Jurassic
and Permian; and to the latter they are unconformable. They therefore
either belong to the Triassic or to an inferior part of the Jurassic formation.
The rocks of the Upper Colorado, according to Newberry, lie between the
Carboniferous and the Cretaceous, and the whole thickness is 2000 to 2500
feet. But it is not yet known whether all these beds are of the Triassic, or
whether they cover both the Triassic and Jurassic periods. A bed of lig¬
nite with some coal plants was found by Dr. Newberry near the junction
of the Cretaceous and the inferior red sandstone, containing a few fossil plants,
which he observes may possibly be Jurassic, although it is not certain that
they may not be Cretaceous.
n. Life.
There are two remarkable characteristics of the American Trias¬
sic period, according to the present state of discovery :—
1. The paucity of all distinctively marine life in the beds of the
Atlantic border.
2. The absence of life of every kind, excepting some fossil wood
and Reptiles, from the beds of the Western Interior.
There may have been on the Atlantic extensive coast-accumula¬
tions formed, containing numerous marine fossils, as in Europe;
but none such are now exposed to view.
2S
418
MESOZOIC TIME REPTILIAN AGE.
1. Plants.
The vegetation of the Triassic period includes no species of
Sigillaria, Stigmaria, or Lepidodendron, characteristic genera of the
Carboniferous era; but instead there are Cyc.ads * along with
many new forms of Ferns, Equiseta, and Conifers. The figures
beyond show this contrast between the flora, of the Carboniferous
and Triassic eras. Figures 62G and 027 represent the remains of
leaves of some of the Cycads; figs. 052 and 052 «, one of the Coni¬
fers, a Voltzia related to the Cypress ; and figs. 028, 029, and 030 are
species of ferns. Trunks of Conifers occur occasionally in the
sandstone. One found near Bristol, Ct., was fifteen or more feet
long and one foot in diameter. No species of grass or moss have
been met with. Many plants of remarkable forms found in Con¬
necticut and Pennsylvania remain to be described.
The remains of plants are sufficient to show that the hills had
* Gymnosperms (p. 166) are divided into (1) Conifers, comprising the Pine,
Spruce, Hemlock, etc.; (2) Sigillarids, the Sigillarife of the Palaeozoic; (3)
Cycads, the plants above alluded to, of which the two most prominent groups
are named Cycas and Zamia.
The Cycads, while related to the Conifers in structure and fructification, are
totally different in habit. They have a simple trunk, with a tuft of large
leaves or fronds at top, and thus
much resemble a Tree-fern or young
Palm. The fronds unroll in expand¬
ing, as in the Ferns, but their form
is closely like that of many Palms.
Yet, while resembling palm-leaves in
shape, the leaflets have no tendency to
split longitudinally, as in that tribe.
Fig. 625 a represents a trunk of a short
extinct species, a foot and a half in
diameter, and 625 b one of the long
fronds from the graceful cluster that
crowns the top in a Zamia ; both are
very much reduced in size. The
species of Cycas are sometimes 30
feet high, but those of Zamia are
usually short, seldom exceeding 3 or
4 feet. The existing species are con¬
fined to warm climates, occurring in
the West Indies, Mexico, and equatorial South America ; in southern Africa
and Madagascar; in southern Asia, Japan, and the East Indies; and in
Australia.
TRIASSIC PERIOD.
419
their forest-vegetation of Conifers, Cycads, and Ferns, from which
old trunks and leaves were occasionally swept into the estuaries,
while the marshes were in some places accumulating vegetable
debris and forming coal.
Characteristic Species.
Conifers.—The genus Voltzia, near the Cypress, has lax leaves, with the
terminal often longer than the others; the fruit-branchlet consisted of broad
Figs. 626-630.
Fig. 626, Podozamites lanceolatus; 627, Pterophyllum graminioides; 628, Clathropteris
rectiusculus; 629, l'ecopteris Stuttgartensis; 630, Cyolopteris Linnseifolia.
and short leaves or scales. A species near V. heterophylla (fig. 652) has been
found in the American rocks. One was found at the Little Falls of the Passaic,
in New Jersey. Several Fir-cones, six inches long, have been found at Phoe-
nixville, Pa., and a small one, from the Massachusetts beds, has been figured
by Hitchcock.
Cycads.—The Pterophyllum longifolium Braun, from North Carolina and
Pennsylvania, is characteristic of the Upper Trias in Europe; the species
resembles fig. 653; Pterophyllum graminioides, fig. 627, is another North Caro-
420
MESOZOIC TIME REPTILIAN AGE.
lina species. Fig. 626 is the Podozamites lanceolatus Emmons, from the same
locality.
Acrogens.—Fig. 628, Clathropteris rectiuscula Hitchcock, from East Hampton,
Mass., near the middle of the Sandstone formation : in one specimen there
were seventeen such fronds radiating from one stem. Fig. 629, Pecopteris
Stuttgarliensis, a fern with the fruit, from the Richmond Coal beds, found also
in the Trias of Europe. Fig. 630, Cyclopteris linnseifolia, from Richmond. Other
ferns are the Acrostichites oblongus and Laccopteris falcata Emmons, both from
North Carolina. Equisetum columnare occurs at Richmond, Va., and in Penn¬
sylvania. One or two Catamites have been found in North Carolina.
The vegetation of the beds is decidedly Triassic in character. Pecopteris
Stuttgartensis and Pterophyllum longifolium are Upper Triassic in Europe;
Laccopteris falcata closely resembles L. germinans, an Upper Triassic spe¬
cies; Cyclopteris linnseifolia is near C. pachyrachis, also Upper Triassic;
Clathropteris and Voltzia are Triassic or Jurassic. The prevalence of Cycadeae
is decidedly Triassic, and not Permian. Catamites and species of Neuropteris
occur in the European Trias as well as in the Permian and Carboniferous.
2. Animals.
The Triassic rocks of the Atlantic border have afforded no traces
of Radiates, and but few Mollusks. This singular fact is partly
accounted for through another already stated,—that the beds are
rarely marine, being in general either fresh-water or brackish-water
deposits.
Articulates are represented by both Crustaceans and Insects. The
Crustacean remains are, with a single exception, Ostracoids; and
some of the species occur in great numbers: two of them are repre¬
sented in figs. 631, 632. The only fossil Insect observed is the
larve (or exuvia of the larve) of a Neuropter (fig. 632 B) related to the
genus Ephemera, found by R. Field in the shale at Turner's Falls, on
the Connecticut, and described by Hitchcock. It is about three-
quarters of an inch long. This tribe of Insects appears to have
been numerously represented in the Carboniferous Age (p. 358).*
* Neuropterous Insects have four similar membranous reticulated wings; as
the species of Dragon-fly or Libellula, Termes, Phryganea, Ephemera.
Orthopters have the outer pair of wings a little coriaceous; as the Locust,
Grasshopper, Cockroach.
Coleopters have the outer wings wholly coriaceous and neatly meeting along
the back ; as the Beetles.
Hemipters have the outer wings coriaceous for about half their length only,
as the Squash-bug, or uniformly thin, as the Cicadse; the mouth is a sucking
beak.
Lepidopters have large wings covered with minute scales; as the Butterfly
and Moth.
TRIASSIC PERIOD.
421
But, although relics of Insects and of Crustaceans other than Ostra-
coids are rare, several species of these classes of Invertebrates, and
also of Worms, are indicated by the tracks which they left on the
material of the finer shales. Figs. 033-637 represent some of these
footmarks. Those of Insects were probably made by larves which
live in water, like those of many Neuropters. Nearly thirty species
of Articulates have been named by Hitchcock from the tracks.
The Vertebrates thus far made known from their fossils and foot¬
prints outnumber all other kinds of animal life; and many were
of remarkable size. They include not only Fishes and Reptiles, but
also the first of Birds and Mammals.* Thus the sub-kingdom of
Hymenopters have four membranous veined wings, the anterior the larger;
as the Bee, Wasp.
Dipters have two membranous wings; as the Howe-fly.
These are the more common of the grand divisions of Insects. The Hy¬
menopters are regarded as highest in rank. The Lepidopters, Dipters, and
Hemipters have sucking mouths; in the other tribes mentioned there are jaws.
* With this first appearance of Mammals in the Geological history, a general
view of the classification of this class is here presented.
Among Mammals there are three prominent groups :—
1. Man, who stands apart from the rest, in having the fore-limbs not organs
of locomotion. (See pp. 573, 593.)
2. True viviparous tribes (or non-marsupial), including all ordinary Mammals,
as the Monkey, Lion, Elephant, Ox, Whale, Bat, Mouse, etc.
3. Semi-oviparous tribes (mostly marsupial), in which birth takes place before
the maturity of the young, as in oviparous animals, and including the Opossum,
Kangaroo, Ornithorhynchus, etc. They are the lowest of Mammals. The mar¬
supial species are so called because they have a pouch (in Latin marsupium)
below, for carrying the immature young.
This third group is to some extent parallel in its series of species with the
second, or non-marsupial; that is, there are Carnivores, Herbivores, Insecti-
vores, Rodents, etc., in both groups,—so that the tribes of Mammals are repre¬
sented under both types.
The non-marsupials, or higher Mammals, contain in themselves two distinct
and parallel series, corresponding to two grand divisions:—
1. The Mctjasihenes (from psyag, great, and adcrog, strength).—The superior type,
based on a larger and more powerful type of structure or life-system, as the
Monkey; Lion, and other Carnivores-, Ox, Elephant, and other Herbivores; Whale
and other Mutilates.
2. The Microsthenes (from yurpog, small, and adsvog).—Theinfcrior tj^pe, based en
a snail and weak type of structure or life-system, as the Bats; the Hedgehog, and
other Insectivores ; Mouse and other Rodents ; Sloth and other Brutes or Edentates.
The parallelism between the two groups is complete. The Bats in the latter
represent the Monkeys in the former, the orders having so close relations that
they follow one another in Cuvier's classification; the Insectivores represent the
422
MESOZOIC TIME REPTILIAN AGE.
Vertebrates has from this earliest period of the Mesozoic all its
grander subdivisions or classes represented.
The Fishes are all Ganoids (fig. 638), Unlike the Palaeozoic, they
Carnivores ; the Rodents represent the Herbivores; and the Edentates, or Sloth
tribe, the Mutilates. The Sloth tribe contains some large animals, but they
have overgrown bodies, too bulky to be wielded well by the small life-system
within. A system of structure fitted for active movement would have been
thrown away upon them.
The true classification of Mammals is, hence, as follows:—
I. Arciionts—Man (alone).
II. Megasthenes.
1. Quadrumana, or Monkeys.—The members (or at least the posterior)
furnished with hands,—that is, having a thumb opposable to the
fingers for grasping; incisors two on each jaw; clavicles perfect;
mainma3 pectoral.
They include (1.) The Strepsirrhines, found in Madagascar, and
diverging thence to Africa and the East Indies, having curved
or twisted terminal nostrils, and the second digit of the hind
limb a claw.
(2.) The Plutyrrhines, peculiar to South America, having the nostrils
subterminal and wide apart, the thumb of the fore hand not
opposable, or wanting, and the tail in most prehensile.
(3.) The Catarrhines, confined to Africa and Asia, excepting one at
Gibraltar, having the nostrils oblique and approximated below,
and opening above and behind the muzzle; the thumb of the
fore hand opposable.
These are the higher species, and among them the highest group is
tail-less (the Orang and Chimpanzee).
2. Carnivores (Flesh-eaters, Beasts of prey).—Feet with claws (ungui-
culate) and the lower surface having the special sense of touch. The
incisors three either side in each jaw (except in the Seals), and the
canines one; canines longer than the other teeth. Molars trenchant
or tuberculatc, according as the food is more or less completely of
flesh; clavicle rudimental or wanting.
(1.) Digitigrades.—Walking on the toes, without touching the heel
to the ground, as the Lion, Cat. Dog, Weasel.
(2.) Plantigrades.—The palm of the hind feet touching the ground
in walking, as the Bear, Raccoon, Badger.
(3.) Pinnigrades.—Moving by means of fin-like paddles, as the
Seal, Walrus.
3. Ungulates, or Herbivores (Plant-eaters).—Feet hoofed, unfit for
grasping, and of low tactile sense; the limbs restricted in use to sup¬
port and locomotion. Molars with broad summits, for grinding.
No clavicles.
The number of toes is either even or odd,—that is, either two or
four, or one, three, or five; and an important distinction is based
upon this by Owen :—
(1.) Artiodactyls, or even-toed.—Dorso-lumbar vertebrae nineteen.
Horns, if any, in pairs. Include (1) the Ruminants, or animals
TRIASSIC PERIOD.
423
include species that have the tails only half-vertebrated, or not at
all so. And thus it is that the progress of the Ages, as first observed
by Agassiz, is marked in the tails of the Fishes.
that chew the cud, which are all two-toed, as the Cow, Sheep,
Antelope, Anoplotherium, Camel. (2) The Omnivores, as the Hog.
(2.) Perissodactyls, or odd-toed. Dorso-lumbar vertebrae more
than nineteen. Horns, when any, never in pairs. Include (1) the
Solidungulates (solid-hoofed), or one-toed, as the Horse, Ass,
Anchitherium, Hipparion [Macrauchenia?]. (2) Multungulates,
having three or five toes, as the Tapir (hind feet three-toed,
front four-toed), Rhinoceros (three-toed), Palacotherium (three-
toed), Lophiodon, etc. (3) Proboscidia, as the Elephant, Mas¬
todon, having five toes, and a proboscis, with tusks from one or
both jaws.
4. Mutilates.—-The limbs short and paddle-like, for swimming. (1)
Cetaceans, as the Whales. (2) Sirenia, as the Lamantin or Manatus,
and the Dugong or Ilalicore.
III. Microsthenes.
1. Chiropters, or Bats (analogues of the Quadrumana).—Having wing¬
like expansions of the fore limbs. Mammae pectoral. Hibernate.
Subdivisions—(1) Insectivores, or Insect-eaters, and (2) Frugivores,
or Fruit-eaters.
2. Insectivores (Insect-eaters, analogues of the Carnivores).—The
molar teeth studded with conical points and associated with inci¬
sors and canines. Legs short. Slow in movement, as the Mole,
Shrew, Hedgehog.
3. Rodents, or Gnawers (Fruit and Root eaters, analogues of the Her¬
bivores).—Molars with flat, grinding summits; two long incurved
incisors in each jaw, separated by a wide space from the molars:
as the Mouse, Squirrel, Beaver, Porcupine, Capybara. Many hiber¬
nate.
4. Brutes, or Edentates (analogues of the Mutilates).—The incisors and
canines, with a rare exception, wanting, and some species wholly with¬
out teeth. The sacrum made of two united vcrtebrm, as in Reptiles.
Twenty-three ribs,—an unusual number, also a Reptilian feature.
The teeth without enamel, and none ever replaced by a new set. Legs
with claws, but motions all slow. Include—
(1.) The Dasypus or Armadillo group, covered with scales or a
carapax,—e.g., Armadillo or Dasypus, Chlamydophorus, Glyp-
todon, Chlamydotherium, Pachytherium.
(2.) The Bradipits or Sloth tribe, without a carapax or coat of
mail, and mostly covered with hair; furnished with molars, as
the Sloth, Megatherium, Megalonyx, Mylodon, Scelidotherium.
(3.) The My rruecophagus or Ant-eater tribe, as the Myrmecopha-
gus (Ant-eater), Orycteropus.
IV. Semi-oviparans, or Ooticoids.
1. Marsupials (from mars opium, a. pouch).—Young prematurely born, and
carried while still in the embryonic state in a pouch over the belly,
424
MESOZOIC TIME REPTILIAN AGE.
The Reptiles must have been very diversified in form and size,
but, although fragments of the skeletons of several species have
been found, a much larger number are known only from their foot¬
prints. The fossils have been discovered in Prince Edward's
Island (Nova Scotia), Pennsylvania, and North Carolina. One of
the most interesting localities is at Phoenixville, Pa., where there is
literally " a bone-bed," as recently described by Wheatley. Some
of the teeth of the Reptiles are shown in figs. G45-G48. The ani¬
mals belonged, apparently, to the tribe of Lacertians (Lizard tribe),
and to that of Labyrinthodonts. Fig. G45, from the tooth of a Rep¬
tile found in Prince Edward's Island (Balhygnathus borealis Leidy) is
reduced one-half.
There may also have been Flying Reptiles, Pterodactyls or species
of some other unknown genus of Pterosaurs; for a fossil found
by Wheatley at Phoenixville, Pa., much resembles, according to
Leidy, the wing-finger of such a Reptile : it consists of two slender,
hollow bones joined by an articulation. None of the footprints
correspond in form to the foot of a Pterodactyl; but it is doubtful
whether any tracks of a flying species could reasonably be looked
for.
The Reptilian footprints (figs. 639-G44) vary from a length
of one-fourth of an inch to twenty inches, and many of them
with the mouth attached to the nipples; having two bones, called
marsupial bones, attached to the anterior margin of the pelvis; as the
Opossum (Didelphys), Kangaroo (Macropus), etc.
2. Monotremes.-—Without teeth; no external ears; no pouch, but still
having marsupial bones:—e.g. (1) the Ornithorhynchus, having a
covering of hair and a duck bill; (2) the Echidnus, having a cover¬
ing of spines and hair, with the habit of the Porcupine.
This order includes several groups, which are approximately paral¬
lel with those of the Non-marsupials.
(1.) Marsupial Monkeys.—Ex., the genus Phalangista (Phalangers),
Phascolarctos.
(2.) Marsupial Carnivores.—Ex., Dasyurus (Bear-Opossum),Thyla-
cinus (Dog-faced Opossum), Thylaeolco.
(3.) Marsupial Herbivores (approximately).—-Ex., Hypsiprymnus,
Macropus (Kangaroo), Nototherium; and of the Pachyderm
tribe, the great Diprotodon.
(4.) Marsupial Insectirores.—Ex., Perameles (Bandicoots), Chscro-
pus, Myrmecobius, Didelphys (Opossum).
(5.) Marsupial Rodents.—Ex., Phascolomys (Wombat).
(6.) Monotreme Edentates.—Ex., Echidnus, Ornithorhynchus.
The living -species are confined to Australia, Tasmania, and the conti¬
nent of America, one species—the Opossum—occurring in North
America, north of the Gulf of Mexico.
TRIASSIC PERIOD.
425
appear to have been made by Batrachians or Labyrinthodonts.
While the smallest tracks indicate species of diminutive size ^s com¬
pared with a modern frog, the largest must have been of enormous
dimensions. Professor Hitchcock calls the most gigantic of these
species Otozoum Moodii. The animal had a stride of three feet, and
appears to have walked like a biped, only occasionally bringing his
fore feet to the ground, as impressions of the latter are not often
distinct. Fig. 044 is the fore foot of this species, much reduced
(twenty inches being its full length), and 644a the hind foot: their
relative sizes are here retained. One of the specimens of this spe¬
cies in the Amherst Cabinet is a slab thirty feet long, containing
eleven tracks.
In some species the impressions of the hind feet have but three
toes and resemble the tracks of birds. This is seen in fig. 641 a.
(Anomcepus scambas Ilk.).
The print of the fore foot of the same animal is four-toed, as
shown in fig. 641. These figures are one-sixth the natural size. It
is remarkable that the toes of the hind feet have two, three, and
four phalanges successively, like the toes of birds,—a peculiarity
now unknown among Reptiles, but which characterized afterwards
the Iguanodon, the giant Reptile of the Wealden.
Professor Hitchcock has described over fifty species of Reptiles
from the tracks found in the sandstone of the Connecticut valley.
The evidence with regard to the existence of Birds at this period
has been shaken somewhat by the discovery of the three-toed rep¬
tile-tracks ; and it is not impossible, as was early suspected, that
all the supposed bird-tracks may turn out to be Reptilian. Still,
this does not appear probable.
The largest of the bird-tracks was of gigantic size, like the
largest of those of the Reptiles. Fig. 649 shows the form. It was
nearly two feet long; and from its depth and the great length of
stride it is evident that the animal was tall and heavy,—probably
fourteen feet high, exceeding the Ostrich of our day, and even
the huge Moa of New Zealand. Smaller species were common,
and many of them have been described. Fig. 649 A (from Hitch¬
cock) represents a large slab, with its lines of tracks, showing
that a number of birds (a, b, c) and batrachians (c/) passed along
over the muddy surface during the same day, or before the
tides or freshets made new depositions of detritus: the tracks
a, a, are enlarged views of b, and still are only one-tenth of the
natural size. The birds of the period appear to have been either
long-legged waders, or species of the Ostrich type. None were
web-footed.
426
MESOZOIC TIME—REPTILIAN AGE.
The number of species of birds named by Hitchcock from the
footprints of the Connecticut valley is thirty-one.
Fossil bones have been obtained from these beds at Windsor, Ct.
They are hollow, and may have belonged to birds ; but Dr. Wyman
states that it is also possible that they were the bones of Flying
Reptiles.
The only Mammal thus far made known was discovered by
Professor Emmons in North Carolina. The specimen is a jaw¬
bone (fig. 050), and it belonged, according to Professor Owen, to
an Insectivorous (Insect-eating) Marsupial near the modern genus
Myrmecobius of Australia. The species has been named by its dis¬
coverer Dromatherium sylvestre.
It is altogether probable that Mammals of similar kind were
associated with the Birds and Reptiles in the Connecticut valley.
To give some idea of the general form of the earliest of Mam¬
mals, a drawing of the Myrmecobius is given in fig. G63 B. The
genus is confined to Australia.
1. Mollusks.—Conch'/ers.—Myacites Pennsylvanicus Conrad, from the Black
slate of Phcenixville, Pa. Two other species, referred by Wheatley with a query
to Pholadomya and Unio or Potamomya, occur at the same locality.—An
imperfect shell from near Mount Tom, Mass., is referred by E. Hitchcock, Jr.,
to the Kudistes.—The Posidonise, formerly supposed to be Molluscan, are now
regarded as Crustaceans of the genus Estheria.
2. Articulates.—(a.) Crustaceans.—Ostracoids : Fig. 631, Estheria ovata
Lea (Posidonia minuta), from Richmond, Va., and Phcenixville, Pa., resembles
the P. minuta of the European Trias; fig. 632, E. oralis Emmons, from North
Carolina, and fig. 632 A, E. parva Lea, Phcenixville, Pa., are both E. ovata ac-
Fig. 631, 632, 632 A, Estheria ovata; 632 B, Palephemera mediceva (X j).
cording to T. R. Jones. Two species of Cypris, one smooth and the other granu¬
late, occur at Phcenixville and Gwynned, Pa. Figs. 636, 637 represent tracks
referred by Hitchcock to Maerouran Crustaceans.
(b.) Insects.—Fig. 632 B, exuvia of a Neuropterous larve, related to Ephemera,
according to J. L. Le Conte. The appendages along the sides are probably
Characteristic Species.
Figs. 631-632 B.
32 A
TRIASSIC PERIOD.
427
branchim attached to the abdomen. Tracks of different insects are shown in
figs. 633-635, from Hitchcock. On comparing especially figs. 633, 634 with
Figs. 633-637.
Figs. 633-035, Tracks of Insects; 636, 637, Tracks of Crustaceans?
the footprints of some living Insects, Dr. Deane found a close resemblance
between them.
3. Vertebrates.—(a.) Fishes.—Fig. 638, Catopterus gracilis Redfield (re¬
duced one-half), from Middlefield, Ct., and also from North Carolina and Phoe-
nixville, Pa.; 638 a, scale of same, natural size. There are also other species
Fig. 638.
Fig. 638, Ganoid, Catoptorus gracilis ( X %); a, Scale of same, natural size.
of Catopterus; also species of hchypterw, and of Turseodus Leidy (related to
Belonostomus or Eugnathus). In the last the tail is not at all vertebrated
or heterocercal. Radiolepis speciosus Emmons is another Ganoid, from North
Carolina and Pennsylvania.
The best localities of fossil fishes are Sunderland, Mass.; Middlefield Falls
and Southbury, Ct. ; Richmond Coal beds, Va.; Phoenixvillc, Pa.
(b.) Reptiles.—(1.) Amphibians.—Fig. 643, Avisojms gracilis Ilk., reduced one-
third. Fig. 642, Anisopus Reweyanus Ilk., half natural size. Fig. 639, Macropterna
divaricans Hk. (reduced to one-sixth), may also be Batrachian. Fig. 644, Oto-
zoum Moodii Hk., is possibly allied distantly to the Labyrinthodonts, although
differing much from the known Labyrinthodont tracks. Portions of the ske¬
leton of Labyrinthodont Amphibians have been detected by Leidy among the
428
MESOZOIC TIME REPTILIAN AGE.
fossils of Gwynried, Pa., twenty miles north of Philadelphia, and also among
those found at Phcenixville; and Emmons has figured a portion of the head of
a fine species from North Carolina.
Figs. 639-644.
Fig. 639, Macropterna divaricans ( X %)'* 640, Apatichmis bellus ( X V-z)\ 641, Anomoepus
scamljus, fore foot ( X Fg )> 641a, hind foot of same; 642, Anisopus Deweyanus, fore foot
( X >£): 642a, hind foot of same: 643, A. gracilis, fore foot (X%); 643 a, hind foot of
same; 644, Otozoum Moodii, fore foot; 644a, hind foot of same (both X A )•
(b.) Lncerlinns.—Fig. 647 is a tooth,
ty'vauicHu Lea. It has a sharp denti¬
culate edge. Occurs in Division 1 in
North Carolina, and also near Phcenix¬
ville, Pa. Centemodon sidvutus Lea is
the name of a related Reptile from Phce¬
nixville. Fig. 648 is a striated tooth
of liuliodon Curolinensis Emmons. Fig.
646, tooth referred to a Palieosaur,—one
of the Thecodont Lacertians,—a short
and broad flattened tooth. Fig. 645,
BathygnatliHs borealia Leidy, from Nova
Scotia (reduced one-half). Coprolites
are abundant in the shales of Phcenix¬
ville. Fig. 641, a, Aimmcepus scnmbiis
Hk., is probably the track of a Lacer-
tian, but its relations are very doubtful.
A general review of the Pennsyl¬
vania species, with notes on others,
is given by Wheatley in Am. Jour. Sci.
[2] xxxii. 41.
natural size, of the Clepsysaxirus Penn-
Figs. 645-648.
Fig. 645, Batliygnathus borealis (XV2R
646, Palaeosaurus Carolinensis; 646 a, sec¬
tion of same: 647, Clepsysanrus Pennsyl-
vanicus ; 648, Rutiodon Carolinensis.
TRIASS1C PERIOD.
429
(c.) Birds.—Fig. 649, Brontozoum giganteum Hk., reduced to one-sixth natural
size. Fig. 649 A represents part of a slab of sandstone figured by Hitch-
Fig. 649. Fig. 649 A.
Brontozoum giganteum (X %)■
Slab of sandstone, with tracks of
Birds and Reptiles ( X Jo )•
cock, one-thirtieth natural size lineally: a, b, c, are three kinds of bird-like
tracks; a and c are of the genus Brontozoum Ilk.: a, a, same as b, but drawn
larger to show the articulations of the toes. Figs, d, e, are two kinds of Rep¬
tilian tracks of the genus Anisopus Ilk., d Anisopus Deweyanus Ilk. Natural
length of a, 4 inches; of b, 8 to 9 inches; of c, 32 inches; of d and e, 1 to 1£
inches. The best localities of tracks of birds and other animals are at Green¬
field and Turner's Falls, Mass.; Portland, Conn.
(d.) Mammals.—Fig. 650, JDromatherinm sylvestre Emmons, from North Caro¬
lina. Owen says of the species that" this Triassic or Liassic Mammal would appear
Fig. 650.
to find its nearest living analogue in Myrmecobxus ; for each ramus of the lower
jaw contained ten small molars in a continuous series, one canine and three
conical incisors,—the latter being divided by short intervals."
430
MESOZOIC TIME REPTILIAN AGE.
IU. Disturbances—Igneous action—Trap rocks.
Trap ridges and dikes accompany this formation on the Atlantic
border. The rocks constituting them are of igneous origin, and
were ejected in a melted state through fissures in the earth's crust.
It is remarkable that these fractures should have taken place in
great numbers just where the Triassic beds exist, and only spar¬
ingly east or west of them. The igneous and aqueous rocks are so
associated that they necessarily come into the same history.
The era of these ejections is supposed to have begun near the
middle of the Sandstone period. But it may have continued into,
or been mostly confined to, the period next following the deposi¬
tion of the beds. Professor Hitchcock reports that near Mount
Tom tufaceous layers made of fragments of scoria intervene be¬
tween the sandstone beds near the middle of the series, proving
that the ejection took place before the following beds had been
deposited ; but after an examination of the region the author re¬
gards it as more probable that the appearance of scoria is owing
to an escape of steam laterally from between the opened strata
during the ejection of the trap of the adjoining mountain. Mount
Tom and Mount Ilolyoke, of Massachusetts, are examples of these
trap ridges ; also East and West Rock, near New Haven, and the
Hanging Hills, near Meriden, in Connecticut; the Palisades along
the Hudson, in New York ; Bergen Hill and other elevations in
New Jersey.
In Nova Scotia there is a long range of trap skirting the whole
red sandstone region and facing directly the Bay of Fundy; Cape
Blomidon, noted for its zeolitic minerals, lies at its northern ex¬
tremity, on the Bay of Mines.
In Connecticut the ridges and dikes are exceedingly numerous,
showing a vast extent of igneous action.
The following map (fig. 651), from a more complete one of the
State by Percival, will give some idea of their number and posi¬
tion. They commence near Long Island Sound, at New Haven,
just south of the southern portion of the map, where they form
some bold eminences, and extend through the State, and still far¬
ther north, nearly to the north boundary of the State of Massachu¬
setts. Mounts Holyoke and Tom are in the system. The general
course is parallel with that of the Green Mountains.
Although the greater part of the dikes are confined to the sand¬
stone regions, there are some lines outside, intersecting the crys¬
talline rocks and following the same direction. These also may be
parts of the system, for those in the sandstone actually intersect
TRIASSIC PERIOD.
431
these crystalline rocks, underneath the sandstone. Even the little
Southbury Triassic region has its trap, and it has the same direction
as in the Connecticut valley.
The trap usually forms hills with a bold columnar front and
Fig. 651.
Map of part of the region in central Connecticut between New Haven on the south and
Windsor on the north, showing the trap dikes which intersect the region; a, b, c, d, e,
course of western boundary of Triassic, beyond which the rocks are metamorphic.
432
MESOZOIC TIME REPTILIAN AGE.
sloping back. In many cases it occurs simply as a narrow dike.
It has come up through fissures in the sandstone, and, as it escaped,
it often thickened up into high elevations; yet nowhere does it
seem to have flowed far over the surface. In many cases it has
made its way out by opening the layers of sandstone ; and, owing to
the direction of the dike or fissure, and that which this lateral
escape was calculated to produce, the ridge of trap has often as¬
sumed a curved form, as apparent in the map.
The proofs that the trap was actually melted are abundant. For
the sandstone rocks have in many places been baked to a hard grit
by the heat, and at times so blown up by steam as to look scoria-
ceous. In some places the uplift has opened spaces between the
layers, where steam has escaped and changed the clayey sandstone
into a very hard rock looking like the trap itself. Occasionally
crystalline minerals, as epidote and tourmaline, are among the
results of the baking. The evidences of heat, moreover, diminish
as we recede from the ridges; and there is no doubt that the sand¬
stone has been extensively worn away by waters where it had not
been rendered durable by the heat.
In all the several regions along the Atlantic border the strata are in most
parts much tilted. In North Carolina there is in general a dip of 10° to 22°
to the southwest (Emmons); in Virginia, Maryland, Pennsylvania, and New
Jersey, the dip is to the northwest or north-northwest (Rogers) : in Connecti¬
cut and Massachusetts, to the east or southeast (Hitchcock). But there are
many variations at short intervals. In the Portland quarries there are joints
on a grand scale, having two transverse courses, nearly north-and-south and
east-and-west.
Some of the dikes of trap and fissures in the sandstone in Con¬
necticut and New Jersey contain copper-ore (copper-glance, eru-
bescite and malachite), and there is little doubt that the copper
veins, and the barytes which is often the gangue of the vein, ori¬
ginated in the same period of eruption. The red color of the
sandstone—a consequence of oxydation of magnetic-iron grains
present in it—appears to have had its origin in the same cause.
This history of the Triassic of the Atlantic border and its trap
dikes appears to be a repetition of what took place long before,
during both the Huronian and Potsdam periods, in the Lake
Superior region, wdiere a similar subsidence (10,000 feet in the
former, and 3000 or 4000 in the latter), and similar igneous erup¬
tions, accompanied the formation of the beds.
TRIASSIC PERIOD.
433
2. FOREIGN TRIASSIC.
The region over which the Triassic rocks outcrop in England
stretches across the island from south-southwest, along by the
British Channel, to the north-northeast, and also from the centre
of this band, along a northwestward course, to Liverpool, and
thence north up the west coast, thus dividing England into four
parts,—a southwestern (the peninsula of Cornwall and Devon), a
southeastern, a western (Wales), and a northern,—indicating the
existence of an archipelago of British Isles in the Triassic period.
In Euroj^e the Trias is found largely developed in regions east
and west of the Rhine, from northern Switzerland northward; on
the east side, through Wurtemberg, Odenwald, Thuringerwald, and
by Giessen; and on the west side, along the Yosges, by Strasbourg
and Metz, to Aix. The beds occur also in other parts of central
Europe, in the eastern Alps, Poland, Russia, Spain, etc.
I. Rocks: kinds and distribution.
The subdivisions recognized in France and Germany are three in number;
whence the name, from the Latin tria, three. The beds are denominated in
these countries and England as follow, beginning with the lowest:—
I. England. II. France. | III. Germany.
Saliferous beds, or 1. Gres bigarre. j 1. Bunter Sandstein, 1200 to 1600 ft.
New Red Sandstone, 2. Calcaire Coquillier. j 2. Muschelkalk, 1000 to 1200 feet.
1200 to 1700 feet. 3. Marnes irisees. j 3. Keuper.
In English works the names of the European beds are translated as follow:
1. Variegated sandstone; 2. Shell limestone ; 3. Red marls or Keuper;—yet they
are often written without translation. The names indicate the kinds of rocks.
In England they are sandstone and mottled clays (marls), mostly red; in Europe,
near the Rhine, a thick fossiliferous impure limestone lies between a sandstone
above and marls below.
This formation contains the principal salt beds of Europe, and hence it is
often called the Saliferonx eystem. The salt in Germany is connected with the
middle group, as in Wurtemberg, where there are noted salt-works. In Vic and
Dieuze, France, they are in the upper; and a thickness of 180 feet of rock-salt
occurs in the course of 650 feet of rock. The salt layers alternate with clay
and gypsum or anhydrite. In England the upper part affords the salt; and at
Northwich, in Cheshire, two beds of salt, nearly pure, are 90 to 100 feet thick.
II. Life.
The species of fossils in the European Triassic are far more
varied and numerous than in the American. The beds have
29
434
MES0Z01C TIME REPTILIAN AGE.
afforded teeth of one species of mammal, but fail of relics of birds.
Near Wurtemberg, Germany, there is a bone-bed, full of bones of
fishes and reptiles, in the upper part of the "Keuper," and another
in the " Muschelkalk and in England a similar bone-bed exists
near the top of the series.
1. Plants.
Equiseta, Ferns, Cypress evergreens, and Cycads are the prevail¬
ing forms. No true Grass, Moss, Palm, or Angiosperm has yet been
found in beds of this period.
Characteristic Species.
Fig. 652 is a branch of the Vo/tzia heterophylla, of the Cypress group. Fig.
653, Pterophyllum Jsegeri, from Stuttgart. There are also species of Equisetum,
Catamites, etc. Some names of European plants are given on p. 420. jEtho-
Figs. 652, 653.
Fig. 652, Voltzia heterophylla; 652 a, one of its fruit-bearing branches; 653, Pterophyllum
Jsegeri.
phi/llnm speciosum, yE. xtipulare, Eehinostachys oblonga, and E. cylindrica are
names of species of grass-like plants referred to the Typhaceae or " Cat-tail
family.
2. Animals.
Radiates, though not abundant, are represented by Crinoids,
Star-fishes, and a few Corals. Of the first there is the beautiful
TRIASSIC PERIOD.
435
Lily Encrinite, Encrinus liliiformis. Mollusks are numerous, and
among them are the first of the Ammonites. The Articulates are
confined to Crustaceans and Worms.
Among Vertebrates, the Fishes are all
Ganoids or Selachians.
The Reptiles include the gigantic Labyrin-
thodon, a scale-covered animal of a Batrachian
form, the skull of which was three or four
feet long, and the teeth three inches,—mag¬
nitude enough for the Otozoum of the Con¬
necticut valley. The tracks referred to a
genus named Chirothcrium (because of a re¬
semblance in- form to the human hand) are
supposed to be those of a Labyrinthodon.
The rocks also contain remains of Swimming
Saurians (Enaliosaurs) and Lacertian Reptiles.
Remains of 12 species of Labyrinthodonts, 16
of Enaliosaurs, and 12 to 15 of other Saurians,
have been found.
9
The species of Mammal, Microlestes antiquus
(fig. 603 A), is closely related to that of North
Carolina.
Characteristic Species.
1. Radiates.—Fig. 654, Encrinus liliiformis, from the European "Muschel-
kalk." The limestone in some places is mostly made of Crinoidal remains.
Aspidura loricata is a Star-fish related to the Ophiurae.
2. Mollusks.—(a.) Brachiopods.— Terebratula vulgaris, Spirifer nncinatns,
etc. (b.) Conchifers.—Fig. 655, Avicttla f socialis. Fig. 657, Jfyophoria lineata, of
the Trigonia family; also species of Gcrrillia, Aoicula, Pecten, etc. (c.) Cephalopodx
Figs. 655-657.
Conchifers.—Fig. 655, Avicula? socialis; 656, Estheria minuta; 657, Myophoria lineata.
—Fig. 658, Ceratites nodosus, related to the Ammonites, hut differing in the
greater simplicity of the lobes of the septa. Fig. 659, Ammonite-s tornatus, from
Fig. 654.
Encrinus liliiformis.
43G MESOZOIC TIME REPTILIAN AGE.
St. Cassian; two species of Orthoceras have been described from the same
place.
Figs. 658,659.
Cephalopods.—Fig. 658, Ceratites nodosus ; 658 a, dorsal view of portion of same, showing
the dorsal lobes of the septa; 659, Ammonites tornatus ; 659 a, side-view of same (X %)•
3. Articulates.—(a.) Crustacean*.—Ostracoids : Fig. 656, Estheria (Posido-
nia) minuta.—Macrourans : Fig. COO, Pcmphix Sueurii, a species near the Crawfish
( onus Astacus).—(b.) Insect*.—Species of Curculionites, Gla-
phyroptera, etc.
4. Vertebrates.—(a.) Fishes.—Among Hybodont Sela¬
chians, fig. 469, Hybodus plicatilis Ag.; fig. 468, H. minor
Ag. Among Cestracionts, species of Acrodus, Ceratodus,
etc. Ganoids especially of the genera Saurivhthys, Gyro-
lepis, Amblypterus, and Palaeonisctis, the last of the hetero-
cercal species; and of the Pycnodont division, Pycnodus
yiyas, etc.
(5.) lleptilcs.— (1.) Amphibians of the Labyrinthodont
tribe. Fig. 601, Labyrinthodon (Jfastodonsaurus) (jiyanteus,
reduced to one-twelfth the natural size. Fig. 661 a is one
of the large teeth, reduced one-half. They have the Laby¬
rinthine structure explained on p. 280. Fig. 662 repre¬
sents the prints of the fore and hind feet of a Chirotherium,
one-twelfth natural size, from a slab obtained at Ilildburg-
hausen in Saxony, supposed to be those of a Labyrinthodon.
The larger track in one was eight inches long, the stride four¬
teen inches ; in another, the length was twelve inches. Similar
tracks have been found at Storton Hill in England.
(2.) Lacertians and Saurians.—The species of the Trias have biconcave ver¬
tebra;, like the Thecodonts and Enaliosaurs (in this approximating to the Fishes).
A species of the Permian genus Thecodontosaurus is found in the Trias at Leam¬
ington, England. The Jihynchosaur (R. articcps Owen) had the beak of a Turtle,
without teeth. Simosaur, Nolhosaur, Pistosaur, and Conchiosaur are names of
Fig. 660.
Pemphix Sueurii.
TRIASSIC PERIOD.
437
different genera of Swimming Saurians (Enaliosaura) of the Triassie, whose
remains occur mostly in the Muschelkalk of Europe, and especially at Luneville,
Figs. 661-663.
Reptiles.—Fig. 661, Skull of Labyrinthodon (Mastodonsaurus) giganteus (X i^); 661a.
Tooth of same(X /if, 662, Footprints ofChirotherium (X i^); 663, Footprints of a turtle?.
Bnyreuth, and in Upper Silesia. They are distinguished from the Enaliosatirs of
the Jurassic by the extraordinarily large temporal, orbitary, and nasal openings
through the cranium, which leave little bone. The Nothosaurus mirabilis was
about seven feet long. The teeth were thin, long, and conical, three to five times
as long as broad, striated, slightly inflexed, and inserted in distinct cavities.
Plarodus is another related genus. Two or three Pleviottaurv of the Lias (as
P. Haiokinsii and P. coxtatus) occur in the bone-bed at the very top of the Trias,
Figs. 663 A, 663 B.
['ig. 663 A, Molar tooth of Microlestes antiques, side-view; A', view of crown of same
663 B, Myrmecobius fasciatus (X %)■
or base of the Lias, at Aust Cliff in England. Other Triassie Saurians are the
Petodim of von Meyer {Phytosaurusof Jager), a carnivorous,crocodile-like species,
438
MESOZOIC TIME—REPTILIAN AGE.
with the teeth in sockets; and the T'ermatosaurus of Plieninger, from the Keuper
of Wurtemberg.
(c.) Turtles.—A series of tracks like fig. 663 have been observed in Germany
which have been referred to a Turtle, the earliest representative of the tribe.
The tracks form two distant parallel lines, as they should for an animal having
a broad shell-covered body and short legs.
Coprolites of Reptiles are also common. Various footprints are described
and named in Jardine's Iehnology of Annandale.
(d.) Mammals.—Fig. 663 A represents the side-view of a tooth of Blicrolestes
antiquus Plieninger, from the bone-breccia of Wurtemberg; A', view of crown.
A tooth of the same mammal has been found at Frome, in England. Owen
regards the species as probably near the modern Myvmecobius and closely re¬
lated to another extinct Marsupial genus, Phujiaida.r, found in the English
Upper Oolite. Fig. 663 B represents the Myvmecobius fasciatus, a species of
Marsupial now living in Australia.
Fossils characteristic of the subdivisions of the Trias.
The characteristic fossils of the three subdivisions of the Trias
are as follow :—
1. Lower group.— Voltzia heterophylla, Calamiies Mougeoti, Placodus impressus,
Notho8aurus Sehimperi.
2. Middle group.—Enerinus liliiformis, Avicula 1 socialis (common to all the
groups), Myophoria (Trigonia) vulgaris, M. lineata, Terebratulu vulgaris, Cera-
tites nodosns, Pemphix Sueurii, Hybodus Mougeoti, Placodus (several species),
Notlwsaurus (species differing from those of the lower group), Simosaurus, Pisto-
saurus.
3. Upper group, or Keuper.—Equiseta, Calamites arenaceus, Pterophyllum Jecgeri,
Pt. longifolium, Pt. Munsteri, Estheria (Posidonia) Keuperiana, Labyrinthodon
giganteiis, Belodon, Termatosaurus.
The Estheria minuta ranges through all the divisions.
IV. General Observations.
1. American.
General Progress.—The following points bear upon the history of
this period:—
T. The position of the rocks in linear ranges, parallel with the
mountains, and therefore along depressions in the surface that
were made when the Appalachian foldings took place. The Con¬
necticut valley is one of the great synclinal depressions made at
that time. Such areas would naturally have become inlets ol the
sea, or estuaries, river-courses, lakes, or marshes, and would have
received the debris of the hills brought in by streams.
II. The absence of Radiates, the paucity of Mollusks, and the
TRIASSIC PERIOD.
439
presence of few species that are properly marine. These facts
prove that the ocean had imperfect access, where any, to the re¬
gions,—that the beds are not sea-shore formations like the Creta¬
ceous and Tertiary of later times; and thus they confirm the idea
that the beds are partly of estuary and partly of lacustrine origin.
The occurrence of vegetable remains and the coal beds sustain
this conclusion.
III. The ripple-marks, raindrop-impressions, and footprints.
These show, wherever they occur, that the layer was for the time
a half-emerged mud or sand flat; and, as they extend through
much of the rock, there is evidence that the layers in general
were not formed in deep water. They abound especially in the
upper half of the Connecticut-valley strata.
IV. The thickness,—3000 to 5000 feet or more. We learn from
this thickness, in connection with the preceding, that the areas
underwent a gradual subsidence of 3000 to 5000 feet or beyond;
consequently, that these oblong depressions made at the time of
the foldings were slowly deepening, and continued to deepen until
the last layer was laid down.
V. The tilted and displaced condition of the beds, without evi¬
dence of folds. This inclination has been attributed to deposition
on a sloping surface. But such cases of oblique deposition are
exceptions, and not the general rule ; while in the case of the
sandstone, the layers are inclined 10 to 30 degrees or more, in each
of the great regions. The tilting must, therefore, be a result of
mechanical force ; and, as faults are not numerous, while joints are
common, it follows that the force was very gradual in its action.
Under IV., a profound subsidence vras shown to have been in
progress in the regions of depression occupied by the strata. Such
a subsidence would have brought a strain upon the overlying beds,
and sooner or later would have produced fractures and disturbance;
and if one side or part of the depression were undergoing more
subsidence than the opposite, it wTould have caused that oblique
pushing of the beds that would have ended in faulting and tilting
them. The direction of the dip and strike in such a case would
depend on the relative positions, with reference to the whole basin,
of the parts undergoing greatest and least subsidence.
VI. The sandstone strata intersected by dikes of trap. These
dikes are proofs of fracture of the earth's crust; of more fractures
in the part of the crust directly beneath the formation than out¬
side of the region; therefore of fractures in the old synclinal
depression in progress of subsidence. The subsidence of such a
region would bring increasing tension or strain upon the rocks
440
MESOZOIC TIME—REPTILIAN AGE.
below, which might ultimate in fractures, especially about the
axis of the depression. The tilting, fractures, joints, and ejec¬
tions of igneous rock are, therefore, parts of one connected series
of events.
The manner in which the trap at its eruption has sometimes
separated the layers of sandstone, and in this way escaped to the
surface, instead of coming up through the fissures simply, shows
that the rock had been tilted extensively before the ejection; and,
as the trap dikes intersect the later beds of the formation, the
igneous ejections were among the later results of the period, if not
to a great extent subsequent in time.
It is hence no mystery that rocks of igneous origin are intimately
associated with rocks of aqueous origin in these Triassic regions.
Thus the period of these rocks came to a close somewhat similar
to that of the Carboniferous age. The Carboniferous age ended
in a period of disturbance, escape of heat, as shown in consolida¬
tions and metamorphism, and a complete destruction of life along
the Continental border; and the period of these sandstones was
closed in uplifts, fractures, emissions of heat, consolidations, and
destructions of life. But in the former case the crust was yield¬
ing, and became folded into mountains: in the latter, the action,
though ranging along the same line of coast, from South Carolina to
Newfoundland, was more limited; the stiffened crust only yielded
by breaking; the heat came out in ejected melted rock, instead of
a slow, gentle effusion, and the swelling up of the lava and simple
tiltings of the strata formed hills and ridges. The destruction
of life was in both cases complete.
Life of the Period.—The steps of progress in the life of the globe,
as the Mesozoic era opened in the Triassic period, were especially
important. The storing away as coal of the excess of atmospheric
carbon had purified the atmosphere; and soon after the close of
Palaeozoic time—whose great feature was that its animal life had
made rocks, and its plants, coal—we find higher races breathing
the better air. Saurians become numerous; and the vertebrate
type expands by the appearance of the new classes Birds and
Mammals. Among these types, the Saurian continues rapidly to
rise in perfection with the following period of the age; while the
birds and mammals remain of inferior types, forerunners of an
age of higher progress.
Geography.—The position of the Triassic beds on the Atlantic
border shows that this part of the continent stood nearly at its
present level. The strange absence of Atlantic sea-shore deposits
in the Triassic period may be accounted for by supposing that the
TRIASSIC PERIOD.
441
dry land stretched farther out to the eastward, and that the sea¬
shore deposits were formed, but are now submerged. A change of
level of five hundred feet would take a breadth of eighty miles
from the ocean and add it to the continent.
This important fact—which has been before referred to more than
once, on account of its bearing on the history of the continent—
is presented to the eye in the accompanying map, copied from one
Fig. 664.
Map of the submerged border of the continent off New Jersey and Long Island, with lines
of equal soundings in fathoms; NY, City of New York.
of the charts of the Coast Survey under Professor Bache. The
coast-line on the north is the south shore of Long Island; that on
the west, the coast of New Jersey ; while the Bay of New York (at
the mouth of the Hudson) is near the junction of the two (below
NY). The dotted lines are lines of equal soundings, indicating
depths of 10, 20, 30, 40, 50, GO, 70, 80, 90, 100, 120 fathoms. These
lines run back in a long loop northwestward towards New York
442
MESOZOIC TIME REPTILIAN AGE.
harbor, showing deeper water along this line, and evidently
proving that once the land was above water, with the Hudson
River occupying this channel on its way to the ocean. At two or
three places along this channel there are " deep holes," as they
are called (one of them at 32, where the depth is thirty-two
fathoms), which may have been former sites of New York harbor;
for the waters of the harbor are now about six fathoms deeper than
those about its entrance.
This border, now submerged, has, therefore, in former time been
dry land; it may have been partly so in the Triassic period, and
thus have caused the imperfect connection of the Triassic areas of
the Atlantic border with the ocean.
The Triassic continent spread westward to Kansas, and south¬
ward to Alabama; for through this great area there are no rocks
more recent than the Palaeozoic.
The Triassic beds beyond the Mississippi are remarkable for
their great extent and their paucity of life. They occur in
western Kansas on the east, and along the Little Colorado west,
of the mountains ; and they have been observed at many points
between these distant meridians: it is therefore probable that
they cover a large part of the slopes of the mountains beneath
the Cretaceous and Tertiary rocks of the surface. The discovery
of animal fossils may yet be made in some part of this region.
Yet it is remarkable that the beds should have afforded thus far
no relics of marine life, unless the Saurian remains be an exception.
There appears to be but one mode of accounting for the forma¬
tion of such deposits over this wide territory. The interior sea in
which the Carboniferous limestone of the preceding age—even
wider in its limits—had been formed, must have become more shal¬
low and have been cut off to a great extent from free communica¬
tion with the ocean. Such a shallow salt sea, alternately freshened
and concentrated by the successive rains and droughts of a season,
would be quite unfit for ordinary marine life. Few species could
survive through such alternations; and hence there would be
necessarily a paucity of fossils in the deposits. Examples of such
interior salt seas without marine life now exist. Lake Utah is one,
in the Rocky Mountains. A complete evaporation over any por¬
tions would have deposited salt and gypsum,—the salt to be dis¬
solved and carried off wherever the region admitted of drainage
by outflowing waters, the gypsum to remain in the beds.
Facts observed among the Pacific Coral islands, illustrating the
destruction of life alluded to, have been mentioned on page 250.
These islands exemplify also the origin of the gypsum. According
TRIASSIC PERIOD.
443
to J. D. Hague, there is a deposit of gypsum, two feet thick, on Jarvis
Island, overlying the coral sands of the old lagoon, and others
similar also on Starbuek's, McKean's, and Phoenix Islands. He
attributes the formation of the deposits to the repeated evapor¬
ation of sea-water, long re-supplied by the tides, over the area of
the lagoon, during the time when it wTas gradually being recovered
from the ocean.
Climate.—There are no data yet obtained for comparing the
climate of the Arctic in the Triassic period with that of the Tem¬
perate United States.
In the preceding pages, the beds and the period they represent have been
called Triassic. Yet it is to he understood that they are probably in part
Jurassic.
2. Foreign.
The occurrence of ripple-marks throughout most of the European
Triassic sandstones and marls, and also raindrop-impressions and
cracks from drying, show that the beds are of shallow-water and
mud-flat origin ; and the salt—as explained on p. 249—indicates
that there were flats exposed to occasional inundations of the sea,
where the salt water evaporated. The kinds of rock are similar to
those of the Saliferous region in central New York, although they
belong to very different periods : the history of one is probably
essentially that of the other.
The fossiliferous limestone (Muschelkalk) of the Middle Trias
in Germany indicates that in that region there was for a while an
interval of somewhat deeper waters.
As the alternations in these beds depend on small changes
of level over limited areas, there is sufficient reason for their not
occurring in other regions.
Appendix.—In Asia and Australia there are coal beds of considerable extent,
which have been referred to different periods from the Carboniferous to the
Jurassic. The Asiatic deposits occur at Burdwan in western Bengal, where they
are extensively worked, and about Nagpur in the Deccan, India. In Australia
they cover a large surface in New South Wales, extending inland from the
coast.
The fossil plants of the first region are species of Pevopteris, Glossopteris (an
oblong simple-leaved fern). Txniopteris. Vertebrarin (stems of unknown rela¬
tions), Phyllotheca (of the Equisetum tribe), Zamites, etc. About Nagpur nearly
the same genera and partly the same species occur, excepting the Cycads. In
the Australian beds there is a similar resemblance to the Burdwan coal field.
On account of the absence of the peculiarly Carboniferous genera in both
the Asiatic and Australian beds, and the general similarity of their flora, while
444
MESOZOIC TIME REPTILIAN AGE.
at the same time the Bengal beds contain Cycads, the coal has been referred by
most authors to the Mesozoic, and either the Jurassic or Triassic period.
In the Australian beds there are heterocercal Ganoids; and hence the forma¬
tion cannot be more recent than the Triassic.* Sixty miles south of Nagpur, at
Mangali, beds similar to those of Nagpur occur, which have been referred to the
same period, although there are no plants to demonstrate positive identity ; they
contain Extherias, liomocercal Ganoidand a species of Labyrinthodont,—evi¬
dently a Triassic assemblage of species.
In view of all the facts, it appears probable that the coal beds referred to, both
in Asia and Australia, represent the Triasxic period.
There are other beds at Kota on the Pranhita, related to those of Mangali.
There are still others at the Rajinahal Hills, in central India, the age of which
is more doubtful. They abound in Cycads, and fail of most of the genera
found at Nagpur: they have been regarded as Jurassic.
JURASSIC PERIOD (17).
The Jurassic period derives its name from the Jura Mountains
on the western borders of Switzerland, one of the regions charac¬
terized by the formation.
1. AMERICAN.
I. Rocks: kinds and distribution.
On the Atlantic border, the upper portion of the formation
described in the preceding pages on the Triassic may belong, as
has been observed, to the Jurassic period. As no species of fossils
characteristic of any part of this period have yet been found in
the beds, there is some doubt on this point. The absence of Tri-
(jnnias, Belcmnitcs, Ammonites, and other Jurassic forms, may, however,
be owing to the fact that the strata are not properly of sea-shore
origin.
On the Gulf border there are no rocks of this period anywhere
exposed to view.
* The author, in his notes on Australian Geology, published in his Explor¬
ing Expedition Geological Report (in which one of the Ganoids and many of
the coal plants are figured and described), referred the Australian beds to
the Permian period, on account of the presence of the heterocercal Ganoids, the
absence of Cycads, and the regular continuity of the beds with the Carboniferous
strata below. But the resemblance to the Indian flora must bring all to one
horizon, and the above conclusion seems best to harmonize the facts. Rev. W.
B. Clarke reports true Lepidodendra from the interior of New South Wales,—
from which it appears that the Carboniferous flora is represented on the Austra¬
lian continent.
JURASSIC PERIOD.
445
In the Western Interior region, the Jurassic period may claim a part
—perhaps a large part—of the gypsiferous beds already described:
here, again, fossils are wanting to decide the question of age.
But, apart from these doubtful beds, there are true Jurassic strata
full of fossils, overlying in many places the gypsiferous marls and
sandstone. They have been observed about the Black Hills and
the Laramie Mountains, and also at the base of other ridges in the
Rocky Mountains. The beds consist of impure limestone with
layers of marl.
In the Arctic region, also, there are a number of localities of fossili-
ferous Jurassic strata.
The discovery and identification of the Jurassic of the Black Hills of Dakota
were made by Ilayden & Meek. The rocks occur also at Red Buttes on the
North Platte, west of the Black Hills; also along the southwest side of the
Big Horn Mountains (43£° N., 108° W.), and the northeast side of the Wind River
Mountains; also beyond the AYind River Mountains, on the west; also about
the head-waters of the Missouri:—-at all of which places fossils occur. (Ilayden.)
Another locality is near the valley of Green River, east of Lake Utah (Great
Salt Lake), as announced by Meek & Engelmann.
The rocks observed are in general a gray or whitish marly or arenaceous
limestone, with occasional purer compact limestone beds, intercalated with
laminated marls. The thickness at the Black Hills is about 200 feet; on the
northeast of the Wind River Mountains, 800 to 1000 feet; about Long's Peak,
where the marls are absent, 50 to 100 feet.
The Arctic localities are—the eastern shores of Prince Patrick's Land, in 76°
20' X., 117° 20' W.; the islands Exmouth and Talbe, north of Grinnell Land,
77° 10' N., 95° W.; and Katmai Bay, or Cook's Inlet, in Northwest America,
60° N., 151° W.
II. Life.
Although but little is yet known of the life in America of the
Jurassic period, several genera of Radiates and Mollusks which
mark the Jurassic beds of Europe have here been found, the most
prominent of which are Pentacrinus, Trigonia, Ammonites, and Be-
lemnitcs. The characteristics of Belemnites and Ammonites are
briefly mentioned on p. 15G, and again beyond, on pp. 450, 451.
Characteristic Species.
No plants have been described, except a few by Newberry from a coal seam in
the gypsiferous sandstone of the Upper Colorado, in the Moqui country (near
the meridian of 111°), the age of which is doubtful (p. 417). The observed
genera are Cyelopteris, Pecopteris, Neuropteris, Sph.enopteris, and Clathropteris.
The Clathropteris from near the middle of the Connecticut River sandstone
(fig. 628, p. 419), as suggested by Hitchcock, is some evidence—though far from
446
MESOZOIC TIME REPTILIAN AGE.
decisive—for referring the upper half of that formation to the Jurassic. The
European species of this genus occur in the Lias and Trias.
The species of Radiates and Mollusks here figured were collected at the Black
Hills.
1. Radiates.—Fig. 665, a joint of the stem of Pentacrinus Asteriseus, a
Crinoid with a pentagonal column.
2. Mollusks.—(a.) Concltifers.—Fig. 666, Jfonotis enrta; fig. 667, Trigonia
Conradi; 668, Tancredia IVarreniana. (b.) Cephalopoda.—Fig. 669, young spe-
Figs. 665-670.
Fig. 665, A segment of the column of Pentacrinns asteriscus; 666, Monotis curta; 667, Tri¬
gonia Conradi; 668, Tancredia Warremima: 669, Ammonites cordiformis; 669 a, Side-view
of same, a little reduced; 670, Belemuites densus.
cimen of Ammonites cordiformis; fig. 669 a, side-view of the same; fig. 670,
Belemuites dawns, the upper part broken away.
Among the Arctic fossils of this period, there are at Prince Patrick's Land
Ammonites JPClintovki, a species near A. concavus of the Lower Oolite; and at
Cook's Inlet, Ammonites Wosnessenski, A. biplexf, Belemuites paxillostis, and
Unio Liassinus. A. biplex also is reported to occur in the Chilian Andes, in
latitude 34° S., and probably also in Peru near the equator, as well as in Britain
and Europe.
2. FOREIGN.
I. Rocks : kinds and distribution.
The strata of the Jurassic period in England (seemap, page 354,
on which the areas numbered 7,8, are Jurassic) appear at the surface
over a narrow range of country (averaging thirty miles in width)
commencing at Lyme-Regis and Portland on the British Channel,
JURASSIC PERIOD.
447
and extending across England, north of northeast, to the river
Humber, and still farther north, on the eastern coast of Yorkshire,
almost to the mouth of the Tees. They thus cover eastern England ;
while the western part, from the north to Cornwall, was apparently
an elevated barrier against the ocean. Jurassic beds also occur on
the northeast coast of Ireland, as at the Giants' Causeway, and on
the Western Isles.
Following the line of the British Jurassic belt from Lyme-Regis
and Portland across the English Channel, we come upon an appa¬
rent continuation of the belt in France. It sweeps south by the
borders of Brittany to the central plateau of France, and then east
and north by the eastern boundary of the empire, thus surround¬
ing a large area of which Paris is the centre.
The line of barrier-islands of western England is continued in Brittany in
western France; the line of the outcropping Jurassic, in similar outcropping
Jurassic in France : and the area of the shallow Jurassic sea over eastern Eng¬
land, in the extensive Parisian basin,—a sea which was then the western and
southern border of the German Ocean and covered what are now the sites of
London and Paris.
The central plateau of France—a region of crystalline rocks—is nearly
encircled by Jurassic strata, and the rocks are continued eastward over the Jura
Mountains (by Neufchatel) and along their continuation through Wurtemberg
and Bavaria in southern German}'. They appear also in northern Germany
(Westphalia) and the Alps (Savoy, etc.).
Jurassic beds occur also along the Andes in many regions, from their north¬
ern limit to Tierra del Fuego. They are found in many parts of Asia, and have
been recognized by W. B. Clarke in Australia.
The Jurassic period in England and Europe is divided into three
epochs: (1) the epoch of the Lias, or the Liassic, so designated from
a provincial name of the rocks in England (No. 7 a on the map
referred to); (2) the epoch of the Oolite, or the Oolitic (No. 7 b), so
called because a prominent rock of the series in England is Oolite
(seep. 85); and (3) the epoch of the Wealden (No. 8 on map), named
from a region called The Weald, in Kent, Surrey, and Sussex,
where the beds were first studied.
The Liassic beds consist mainly of grayish limestones, containing
marine fossils.
The Oolitic include other limestones, part of which are oolitic in
texture, along with arenaceous and clayey strata in many alterna¬
tions. One of the limestones is a coral-reef rock. All of the beds
are of marine or sea-shore origin, as the fossils show, excepting
strata in the local Purbeck beds near the top of the series, one
of which, on the island of Portland, is called the Portland dirt-bed.
448
MESOZOIC TIME REPTILIAN AGE.
The Wealden is wholly of estuary or fresh-water origin; the beds
consist of clays, sands, and, to a small extent, limestone.
The prominent subdivisions of the Jurassic formation observed in England
(though not present alike in all its Jurassic regions) are the following, beginning
below : —
I. Lias.
1. Lower Lias: consisting of grayish laminated limestone, with shale
above, and a bone-bed and marls below.
2. Middle Lias : a coarse shelly limestone called marlstone.
3. Upper Lias: beds of clay or shale with some thin limestone layers.
II. Oolite.
1. Lower or Bath Oolite, consisting of—
(1.) The inferior Oolite, a limestone with fossils and layers of sand.
(2.) Fidler's-carth group, or clayey layers.
(3.) The Great Oolite, limestone mostly oolitic.
(4.) Forest-marble group, sandy and clayey layers, with some oolite.
(5.) Cornbrash, a coarse shelly limestone.
The Stonesjield slates, noted for their remains of Saurians, as well as of
the earliest British mammals, and also of insects and other species, occur
near Oxford in England, and belong to the Lower Oolite, below the
Great Oolite.
At Brora, in Sutherlandshire, there is a bed of Oolitic coal of good quality,
three and a half feet thick, which has been long worked: it is covered
by several feet more of impure coal containing pyrites. It is supposed
to belong with the Great Oolite.
2. Middle or Oxford Oolite: consisting of—
(1.) The Kelloway Bock, a calcareous grit, overlying blue clay,
and overlaid by the Oxford clay.
(2.) Calcareous grit and oolitic coral limestone, called the Coral
Rag.
3. Upper or Portland Oolite : consisting of—
(1.) Kimmeridge Clay.
(2.) Shotover Sand, a calcareous rock with concretions.
(3.) The Portland Oolite.
4. Purbeck beds: consisting of (1) the Lower Purbeck, fresh-water marls
with the " Portland dirt-bed," and resting on the upper layers of the
Portland stone; (2) the Middle Purbeck, mostly aJied of marine lime¬
stone, 30 feet thick ; (3) the Upper Purbeck, 50 feet of fresh-water depo¬
sits. The dirt-bed of the Purbeck is the second deposit affording re¬
mains of British mammals. It contains also numerous remains of
Cycads, etc.
III. Wealden.
1. Hastings Sands : sandstone with some clayey and limestone layers,
containing Saurian remains, fluviatile shells, etc.
2. Weald Clay: clayey layers, with some calcareous beds containing
fresh-water shells.
The British subdivisions are for the most part recognized in France, and
have received special names by D'Orbigny. They are (I.) in the Lias, 1, the
JURASSIC PERIOD.
449
Sincmurian (Lower Lias, named from the locality at Semur); 2, Liasian
(Middle Lias); 3, Toarcian (from the locality at Thours); (II.) in the Oolitb,
Bujociun (the inferior part of the Lower Oolite, named from the locality
at Bayeux); 2, Bathonicui (the Great Oolite, Bath Oolite); 3, Cullovian (Kel-
loway Ilock); 4, Oxfordiun (Oxford Clay); 5, Corulliun (Coral Rag); 6, Kim-
menihji«n (Kimmeridge Clay); 7, Portlandian (Portland Oolite).
In the French Juras the most of the above subdivisions may be traced.
There are,—
1. The Lower Lias,—a Lias limestone, called also Gryphite limestone, from the
abundance of the fossil Gryplixa areuata; 2, the Middle Lias, marls; 3, the
Upper Lias, bituminous schists, in some places called Posidonia schists, from
the abundance of Poxidonia Bronnii, with a rough limestone above. The Lias
is overlaid by (1) the Lower Oolite; (2) the Oxford Oolite; (3) the Coral and
Astartc limestone, and Portland beds.
The famous beds of Lithotjraphie slate at Solenhofen, affording remains of
many Insects, several species of Saurians,seven of Pterodactyls, etc., are situated
in the district of Pappenheiin in Bavaria, and are of the age of the Middle
Oolite, or that of the Coral Limestone.
II. Life.
1. Plants.
The land-plants of the Jurassic period are mainly Ferns, Conifers,
and Cycads, as iii the Triassic. Leaves and stems are found in many
Figs. 671-673.
Tig. 671, section from near Lulhvorth Cove, showing stumps of trees (a) in the Portland
"dirt-beil;"' 072, Leaf of a living Zamia (X 2\)b 673, stump of the C.vcad Mantellia (Cy-
cadeoidea) megalophylla (X J0).
of the strata, and remains of a forest in what is called the Portland
dirt-bed (fig. G71) (lower part of the Purbeck), the trees of which
30
450
MESOZOIC TIME REPTILIAN AGE.
were Conifers and Cycads. Fig. G73 represents one of tlie Cycad
stumps, and fig. 072 is the leaf of a modern 7amia, which those of
the Mantellia probably resembled. Near Whitby, on the sea-coast
of Yorkshire, and in the Stonesfield slate, fossil ferns are common.
No Jurassic Angiosperrns are known.
2. Animals.
The Radiates include a number of Crinoids, mostly of the genera
Pentacrinus and Apiocrinus (fig. 720) ; also a variety of Corals (figs.
717-719), Star-fish (fig. 721), and Ecliinoids (figs. 094, 722, 722 a),
having in general a modern aspect, though of extinct species and
mostly of extinct genera.
Among Mollusks there is a great variety of new forms, many
peculiar to the Mesozoic era. The last of the Brachiopods of the
iSpirifcr and Lcptccna families appear in the Lias (figs. 090-097).
These Lept.enas are minute species (fig. 090 a), contrasting wonder¬
fully with the abundant and large Loptamas of the Silurian, when
the family was at its maximum. The prevailing Brachiopods are
of the modern genera Tcrebratula and Rhynch.onclla.
Conchifers comprise several new genera. Gryphwa, of the Oyster
family, having an incurved beak, commences in the Lias; and
Exoyyra, another of the family, with the beak curved to one
side, begins in the Oolite. Tngonia, a triangular shell (successor to
Myoplioria of the Triassic and Echizodus of the Permian), appears
in the Lias.
The Gastergpods are represented by several new modern genera,
besides others that are now extinct. But the type of Cephalopods
especially undergoes great expansion. The genus Ammonites, of
Triassic origin, abounds in species (figs. 700, 701). The shell of the
Ammonite has the septa or partitions fiat over the middle, but flexed
or plicated in a complex manner at the margin: in an upper view
of a septum it seems to be bordered by a few large holes, each of
which is a ramified pocket made by the flexure of the margin.
The animal lived in the outer chamber of the shell; but the mantle
descended into the cavities, and thus it is assisted in holding to its
shell. The siphuncle differs from that of the Nautilus family in
being dorsal. In some species the aperture of the shell had the
simple form in fig. 730 ; in others it was prolonged as in fig. 731.
Over 300 species lived in the Jurassic, besides many Nautili.
In addition to these Cephalopods with external chambered shells
(Tetrabranchs or Tentaculifcrs, p. 150), there were also those having
an internal shell or bone (Dibranchs or Acetabulifers), a group
JURASSIC PERIOD.
which includes very nearly all known existing species. Among
them the most abundant is the Bdcmnite. The fossil is a cylin¬
drical stony body (tig. 070), radiated in structure, having a conical
cavity (or alveolus). The lower part of the cavity, in perfect spe¬
cimens, is occupied by a small chambered cone, called the phraymo-
cone, which has a sipliunele. When unbroken (which is very
seldom), the osselet has a thin expansion above on one or two sides,
which is sometimes much prolonged. One form of it is shown in
figs. 702, 703. The Cephalopod was much like a Sepia. Fig. 732
represents the animal of an allied genus called Aaanthotcuthis.
There were also species of the Sepia or Cuttle-fish family, and Cala-
maries, or Squids; and the ink-bags of these species (fig. 700) are
sometimes found fossil, and also the smaller ones of Belemnites.
Buckland states that he had drawings of the remains of extinct
species of Sepia made with their own ink.
The sub-kingdom of Articulates is represented by various Worms,
Crustaceans, Spiders, and Insects; and of the last, all the principal
tribes appear to have been represented, even to the highest, the
Hymenopters. Figs. 734, 735, are Crustaceans of the Oolite; 733,
73G, remains of Insects. Fig. 733 is a Dragon-fly, or Lihel/ulu (Neu-
ropter); fig. 73(1, the wing-case of a beetle (Coleopter). Fig. 737
is the earliest known of true Spiders,—for the only Carboniferous
species of the class are Scorpions. It is from Solenliofen.
Vertebrates present no marked progress in the class of fishes:
there are only Ganoids and Selachians; and none of the former
have vertebrated tails, this Palaeozoic feature finally disappearing.
The Reptilian type, on the contrary, undergoes an expansion more
remarkable than that of Cephalopods. There are no Labyrintho-
donts. But the true Reptiles come forth in numerous Enaliosaurs
(sea-saurians, p. 34G) of higher grade than the Simosaurs of the
Triassicgas is shown in their solid bony skulls ; in Laeertians and
Croeodilians, many of which were 15 to 50 feet in length ; in great
Dinosaurs, the highest of Reptiles; in Flying Saurians (Ptero¬
saurs), having wings much like bats ; in Turtles of several genera.
The more common genera of Enaliosaurs are Ichthyosaurus, Plesio-
saurus, and P/iosaurus. The Ichthyosaurs were gigantic animals,
10 to 40 feet long, having paddles somewhat like the whale (fig.
708), long head and jaws, numerous (in some species 200) stout,
conical, striated teeth, an eye of enormous dimensions, thin disk-
shaped biconcave vertebrae (figs. 710, 710 a). The I. communis,
found in the Lias of Lyme-Regis and elsewhere, was 28 or 30 feet
long. More than thirty species are known to have existed in the
Reptilian age.
452
MESOZOIC TIME 1
•REPTILIAN AGE.
The Plc.siosa.ur (figs. 712, 715) had a long, snake-like neck consist¬
ing of twenty to forty vertebra, a small head, short body, paddles,
and biconcave vertebra differing little in length and breadth. P.
dolichodcirus (fig. 712) was 25 to 30 feet long. P. macroccphulus is
represented in fig. 715 just as it lay in the rocks. The British
rocks of the Jurassic and Cretaceous periods have afforded sixteen
species of Plesiosaurs ; and in all twenty-one are known, of which
twelve were found in the Lias and seven in the Oolite. The
Plinsaur is another swimming Saurian, near the Plesiosaur: some
individuals were 30 to 40 feet long. Remains of more than fifty
species of Jurassic Enaliosaurs have been found in the rocks.
Many of the Crocodilians were of the Teleosaur typo, having
slender jaws like the Gavial, and also biconcave vertebra;,—the
latter a mark both of antiquity and inferiority. Fig. 714 represents
the skull of one of these species, the Myslriosaur.
The Dinosaurs (p. 340) attained in some species a length of 50
or 00 feet. Unlike all other Reptiles, the sacrum corresponded
to five combined vertebra;, as in the higher Mammals. The Megalo-
saurus Bucklandi was about 30 feet long; the teeth were flattened
and curved, with trenchant edges, and were set in sockets: a
horizontal section of one is shown in fig. 740. It was a terrestrial
carnivorous Saurian.
The Tguanodon of Mantell was an herbivorous Dinosaur, and had
the habit of a Hippopotamus. It was 30 feet long, and of great
bulk: the femur, or thigh-bone, in a large individual was about
33 inches long, and the humerus 19 inches ; the teeth (fig. 745) were
flat, and had a serrated cutting edge like the teeth of the Iguana;
and the jaws had some lateral motion,—indicative of its herbivo¬
rous character. Many of the teeth from old animals are worn off
short. The remains occur in the Weaklen of Tilgate Forest, and
in the Kentish Rag near Maidstone.
The llylccosaur, another Tilgate Forest Dinosaur, had its skin
covered with circular or elliptical plates, and was 29 to 22 feet
long.
The Pterosaurs belong mostly to the genus Pterodactyl. Fig. 739 re¬
presents the skeleton (reduced in size) of P. crassirastris, showing the
forearm, with the outer finger excessively prolonged for supporting
the wing, while the other fingers are free for clinging or grasping.
The species was a foot in length, and the spread of the wings was
about three feet. As in birds, the bones of Pterodactyls are
hollow to fit them for flying; but, unlike birds, they had the skin,
claws, and teeth of reptiles. Their habits were probably those of
bats rather than birds. They range from the Lias into the Chalk.
JURASSIC PERIOD.
453
Birds occur fossil at Solenhofen, both their bones and impressions
of feathers. (See fig. 986, p. 752.)
The Mammals of the Jurassic have been found in the Lower
Oolite at Stonesfield, and in the Upper Oolite in the Portland "dirt-
bed" of the Lower Purbeck.
The relics from the Stonesfield slate are referred by Owen to
Marsupials. Fig. 741 represents the jawbone of the Amphitherium
(Thylacotherium) Broderipii, and fig. 742, the same of the Phasco-
lothcrhnn Backlandi,—each twice the size of nature. The form of
the latter jaw is like that in the Carnivorous Marsupials (especially
the Thyalacini). The former species, according to Owen, is most
nearly related to the Marsupial Insectivores. Two species of 4m-
phithcrium have been found at Stonesfield.
The Portland "dirt-bed" has afforded relics of about fourteen
species of Mammals, along with fresh-water shells and insects.
The species have been referred mostly to the Marsupials, and but
one or two to the Non-marsupial Insectivores.
Characteristic Species.
1. Liassia Epoch.
1. Radiates.—Pentacriiuis Briarcus, from the Middle Lias; Star-fish of
different types, including that of the
Ophiitra. Pig. 694, Diadema seriate,
from the Lower Lias. Also species
of Cidaris and IJemieiditris.
2. Mollusks—(«.) Beachiopods.
—Fig. 095, Leptiena Jfoorci, from the
Upper Lias, interior of ventral valve,
enlarged; fig. 096, dorsal valve of
same; fig. 096 a, same, natural size;
fig. 097, Spirifer Wah-otti, from the
Lower Lias.
Five species of Leptxna, and about twice as many Spirifcrs, occur in the Lias.
While these old Silurian genera are disappearing, the new Brachiopod genus
Thecidca begins, and with it there are a few Lingidx, Ithynchonelhe, and Cranise,
and many Terchratuhe. The genera Lingida, RlrjucJioncUa, and Crania, it should
be remembered, are lines reaching from the Silurian to the present time; and
Tercbratula is another genus dating back to the Devonian.
(b.) Conclnfcrs.—Fig. 099, Gryphiva arcuala, especially characteristic of the
Lower Lias or Gryphite limestone; Gryplixa Cyntbium, of the Middle Lias;
Hippnpodium ponderosnm; fig. 698, Ctenoides gigantea. Other genera are
Pholas, Anatina, Pholadomya, Leda, Cythcrea, etc.
(c.) Gasteropoda.—Tho genera Pteroceras, Planorbis, Paludina, Melania, Nerita,
etc., are supposed to begin here.
Fig. 094.
EchinodErm.—Diadema seriate.
^1- MESOZOIC TIME REPTILIAN AGE.
(<l.) Cephalopoda.— Tetrabranchs.—Fig. 700, Ammonites Nodothuuix, from tlio
Lower Lias; figs. 701, 701 a, A. blsuleittua, from the Lower Lias; A. murtjnrita-
tim, Middle Lias. Bib ranchs.—Figs. 702, 70:?, different views of one of the forms
Braciiiopods and Go-NCHifers.—Figs. 095, 6%, Leptaena Moorei (XT); 69fia, same, natural
size: 097. Spirifer Walcotti; 698, Ctenoides (Plagiostonni) gignntea (X ; 099, Grypksea
arcuata (x ?n).
of a complete osselet of a Belcmnite; fig. 704, B. j^axillosvs, Middle Lias; fig,
704 a, section of same near the extremity; fig. 705, B. pistilliformis.—Also spe-
Figs. 700, 701.
Cephalopods.—Fig. 700, Ammonites Nodotianus; 701, 701 a, A. bisulcatus.
cies of the Calamary family, or Teuthids (having the osselet membranous), of the
genera Beloteuthis, GeoteutAh, etc.: the fossils are the osselet, ink-bag (fig. 706),
and horny claws or hooks from the arms.
JURASSIC PERIOD.
455
The last species of the genus Comdaria occurs in the Lias. The beak-like
mandibles (jaws) of Cephalopods are sometimes found fossil, and go under the
name of Rhyncholites.
Figs. 702-706.
Cephalopods.—Fig. 702, View, reduced, of the complete osselet of a Belemnite,—side-view;
703, Dorsal view of same; 701, a, B. paxillosus; 705, B. pistilliformis; 706,Ink-bag.
3. Articulates.—(or.) Crustaceans.—Genera Eryon, Glyphea, etc., and Cir-
ripeds of the genus PoUicipes, here first found. (b.) Insects.-—Coleopters, gen.
Elater, Melolontha, Berosus, etc.; Neuropters, gen. Ephemera, Lihelhda, Ortho-
phlelna, etc.; Orthopters, gen. Gryllus, etc. ; Hemipters, gen. Cicada, Cimicides,
etc.; Dipters, gen. Asilus, etc.
4. Vertebrates.—(a.) Fishes.—Fig. 707, EEdmodus (Tetragonolepis), a
restoration of the fish; fig. 707 a, scales.
(h.) Reptiles.—All the Reptiles have biconcave vertebrae. Fig. 708, Ichthyo-
456
MESOZOIC TIME REPTILIAN AGE.
taunm communis,- fig. 709, head of same; figs. 710 a, 710 b, view and scctior
of vertebra; fig. 711. tooth of same, natural size. Fig. 712, Plesiosaurus clolicho-
Fig. 707.
Hani
ISBfllil
IMSSS0P
Ganoid.—.Echmodus (Tetragonolepis) (X a> Scales of same.
Figs. 708-714.
Reptiles.—Fig. 708, Ichthyosaurus communis (X \ho); 709, Head of same (X.-iWi 710 a-
710 b, view and section of vertebra of same (X X/Q\ 711, Tootli of same, natural size: 712.
Plesiosaurus dolichodeirus (X so); 713 "> 713 6 view and section of vertebra of same; 714.
Mystriosaurus Tiedmanni.
JURASSIC PERIOD.
457
ile x run ; figs. 713 a, 713 b, view and section of vertebra. Fig. 715, P. macrorrp/ta¬
lus. Fig. 714, Mystriomurus (Teleosaurus) Tiedmauni, of the Crocodilian order.
Fig. 715.
Reptile.—Plesiosaurus macrocephalus (X A).
Other Lias genera of Crocodilians of the Teleosaur family were the J)[acrospon-
dylus and Pelagosaurns, specimens of which are found in
Wurtemberg. Fig. 716 is a coprolite of a Saurian.
2. Oolitic Epoch.
1. Plants.—The following are some of the common
genera: of Ferns, Pecopteris, Tieniopterii, Sagenopterix, Glos-
uoptcris ; of Cycads, Pteropltylluni, Zainites, Palxozctmia,
Jfantellia (or Cycadeoidea) ; of Conifers, Taxitcn, Thuyites,
Dammaritc*. There are also species of Equisctum. Fig. 671,
Portland " dirt-bed," with stumps of trees; fig. 673, Mantel! i a
megalophglln, from the •' dirt-bed."
2. Protozoans.—Sponges.—Sponges are common, and
are of many species. Fig. 717, Scypliia reticulata, from
the Oxford Oolite.
Coprolite.
458
MESOZOIC TIME REPTILIAN AGE.
3. Radiates. (a.) Corah.—Pig. 718, Montlivaltia caryopliyllata, from the
Bath Oolite; fig. 719, Prionastrea oblonga, Lower Oolite. Anabacia Orbiilifcs
is a disk-shape coral of the Fungia family, from the Lower and Middle Oolite.
Figs. 717-719.
Sponge.—Fig. 717, Scypkia reticulata. Polyp-Corals.—Fig. 71S, Montlivaltia caryopliyllata;
719, Prionastrwa oblonga.
(h.) Eehinodnrms.—Fig. 720, Apiocrinus lioyssictnus, from the Coral limestone,
—only the top and lower part of the stem given. Fig. 721, Saccocoma pectinata,
Figs. 720-722.
Echinoderms.—Fig. 720, Apiocrinus Royssianus (XV£): 721, Saccocoma pectinata, i-2,
722 a, Cidaris Blumenbachii.
Star-fish related to Comatulci, from the Middle Oolite; fig. 722, Cidaris Blumen¬
bachii; fig. 722 «, spine of same.
JURASSIC PERIOD.
459
4. Mollusks.—(a.) Conchifers.—Fig. 723, Ostrea Marshii, characteristic of
the Oxford (ICelloway) Clay; fig. 724, Exocjyra Viryida, from the Upper Oolite
Firs 723-728.
Conchtfers.—Fig. 723, Ostrea Marshii; 724, Exogyra Virgula; 725, Grypliam dilatata; 726,
Trigonia clavellata; 727, Astarte minima; 728, Diceras arietina.
(Kimmcridge Clay); fig. 725, Gryphwa dilatata ;
fig. 720, Triijonia c/arelhita, Upper Oolite; fig.
727, Astarte minima, Coral limestone; fig. 728,
Diceras arietina, Coral limestone, a bivalve whose
valves are each elongated into the shape of a
curved horn,—whence the name, from Stg, twice,
and Kcpag, liom.
(l>.) Gasteropods.-—Fig. 729. Neriinea Goodhallii.
Coral limestone. The genus is remarkable for
the elongated form of the shells, and for having
one or more prominent ribs on the inner surface,
partly filling or contracting the interior. The
appearance of the aperture in one species is
shown in fig. 785: the species are confined to the
Jurassic and Cretaceous periods. Purpuroidea
nodidata, from Middle Oolite, P/enrotomaria
Fig. 729.
Nerinsea Goodhallii.
4G0
MESOZOIC TIME—REPTILIAN AGE.
ornate, Lower Oolite, are characteristic forms. The Gasteropoda with an entire
aperture are still far the most abundant species; but a few genera with a beak
exist, and the Purpuroidea (near the modern Purpura) is one example. Except
in the great predominance of species with the aperture entire, the Gasteropoda
have generally a modern aspect: among them there are the genera Bulla, Ptero-
ccra, Ccrithhim, Fumiu, Nerita, Patella ?, and others.
(e.) C'phalopods. — Tetrab ranchs.—Fig. 730, Ammonites Humphreysianus, Lower
Oulite; A. Parkinsuni, Lower Oolite; A. cordatns, Middle Oolite; fig. 731, A. Jason
Middle Oolite; A. refrectus, Middle Oolite; also species of Ancyloeeras and
To.roccras (see figs. 7S7, 789).
Dibrewhs.—Bclemnitcs hastatns, Oxford Clay. Fig. 732, Acanthoteuthis anti-
qitus, Oxford Clay. Also species of the Galemary and Sepia families, as Coee.o-
Figs. 730-732.
Cephalopods.—Fig. 730, Ammonites Iluniphreysianus; 731, A. Jason; 732, Acanthoteuthis
antiquus (X ha)-
tcuthis of the latter. The osselet in the Sepia group is calcareous instead of
membranous (p. 156).
JURASSIC PERIOD.
4G1
5. Articulates.—(a.) Crustaceans.—Fig. 734, Eryon arctiformis, Solen-
hofcn. Fig. 735, Arahseoinscus Brodiei, an Isopod from the Purbcck.
Figs. 733-737.
Articulates.—Fig. 733, Libellula; 734, Eryon arctiformis; 705, Arclneoniscus Brodiei; 730,
Elytron or wing-case of Bnprestis; 737, Palpipes prisons.
(6.) Insects.—Coleopters, genera Carahns, Bnprestis, Coccinclla, etc.; Neurop-
ters, Libellula, Termcs, etc.; Orthoptcrs, Blutta, Achetn, etc.; Ilciniptcrs, Cicada,
etc.; Dipters, Cider, Cltironomm, J fused, etc.; Lepidoptcrs, Tinr.ites, Sphinx;
Ilymenopters, Apiaria. Fig. 733, Libellula, Solenhofen. Fig. 73G, Bnprestis,
Stonesficld.
(c.) Spiders.—Fig. 737, Palpipes prisons.
Fig. 73S.
Ganoid.—Aspidorhynclius ( X ]/g )•
fi. Vertebrates.—(nr.) Fishes.—Fig. 73S, Aspidorhynclius, Solenhofen.
Pycnodont Ganoids (see p. 2S0) occur among the fossils, and one of large size
462
MESOZOIC TIME—REPTILIAN AGE.
from the Upper Oolite is called the Pycnodus gigas. Also Selachians, of the
genera Notidauus, Hyhodus, Aerodits.
(b.) Reptile*. — Fig. 739, Pterodactylua crassirostris, from Solenhofen. Fig.
740, section of the tooth of the Dinosaur J/er/alosauriis Bucklaudi, Stoneslield.
Other Reptiles of the Oolite were the Crccodilians with biconcave vertebra,
Telcosaurus (20 feet), Steneosatints ; with convexo-concave vertebra, Cetiosaurus
(00 feet), etc. ; the Lacertians, Gcosaurus (12 to 13 feet long), Homxosaurus
(6 feet), etc.; Enaliosaurs of the genera Ichthyosaurus, P/esiosaurus, Plinsanrus.
Resides these, there were the earliest Chelonian remains (for only tracks of
Figs. 739, 740.
39 40
Fig. 739, Pterodactylus crassirostris ( X 14) i 740, Section of a tooth of Megalosaurus
Bucklandi.
uncertain character occur in the Triassic). The species Idiochelys Wagneri
(six inches long) and Eueystenuim Wayleri are Turtles from Solenhofen; and
Chelone plauiceps is from the Portland Stone.
(c.) Birds.—See Appendix E, page 751.
(<7.) Mammals.—Fig. 741, Amphitherium (Thylacotherium) Broderipii, twice
natural size, Lower Oolite, Stonesfield. Fig. 742, Phaseolotherium, twice natural
size, Stoneslield. Stereoguathus is the name of another small Stonesfield species,
which Owen suggests may have been an herbivorous mammal. On this point
he says :—" Admitting the herbivority of the fossil, it is not certain that it was
hoofed ; there is nothing in the form and structure of the tooth to prove that.
Both form and structure are compatible with the hoofless muticate type of herbi¬
vorous Mammals, as shown by the Manatee; it is the small size of the Stcreo-
(jnatliui which renders it less probable that it was a diminutive kind of Manatee,
and more probable that it was a diminutive form of Ungulate. But, seeing the
manifold diversities of the multi-cuspid form of molar teeth in recent and ex-
JURASSIC PERIOD.
463
tinet insectivorous unguieulate quadrupeds, it is not impossible but that the
Stereoynathus may have belonged to that order."
Of the species found in the uppermost Oolite, the Purbeck beds, there are the
following:—Trieonodon morda.c Owen, nearly as large as a hedgehog (length
of ramus of jaw, lj inch); another species of the genus, a third larger: they
Figs. 741, 742.
742, Phascolotkerium Bucklandi ( X 2 ).
are allied to the Stonesfield species, and were probably marsupial. Placjiaxdax
BecJclesii and P. minor of Falconer,—probably Carnivorous Marsupials; the former
as large as an English squirrel (length of ramus of jaw, 1} inch), the latter
more than half smaller. Spalacothcrium tricuspid ens Owen,—probably an in¬
sectivorous Marsupial; length of ramus of lower jaw, about an inch. Another
species is the Ericidus of Falconer, regarded by him as an Insectivore not mar¬
supial.
3. Weal den Epoch.
1. Plants.—Conifers closely allied to Araucaria, Abies, (Jupressus, Junipe-
>'»x; Cycads; trees allied to Dracxna, Yucca, and Bromclia ; Equiseta and Ferns;
the delicate Chctree of rivulets.
Figs. 743, 744.
2. Mollusks.—Fresh-water species in large numbers, especially of the
464
MESOZOIO TIME REPTILIAN AGE.
Fossils characteristic of the Subdivisions of the Jurassic.
1. Lower Lias.—Dindema seriale (fig. 694); Pentacrinus Briareus; Spiri-
ferina Walcatti (fig. 697); Gryphepa arcuata (fig. 699); Cardinia conclnna; Cte-
noides (Plagiostoma) gig an tea ; Pleurotomaria Anglica ; Ammonites bisulcatus (or
Buclclandi) (fig. 701), A. Planorbis, A. Gonybeari, A. Nodotianns (fig. 700); Be-
lemnites acntns; Tetragonolepis ; Plesiosaurus, Pterodactylus macronyx.
2. Middle Lias.— Terebratula rimosa, T. numismalis, Gryphcea Cymbium, Pec-
ten aquivalvis, Pleurotomaria expansa, Ammonites margaritatus, A. spinatus, Be-
lemni'cs clavatns, B. paxiUosus (fig. 704).
3. Upper Lias.—Pentacrinus vulgaris; Lcptcena Moorei, etc.; Ostrea Knorri;
Posidonia Bronuii, Turbo subplicatus; Ammonites bifrons, A. heterophyllns, A.
radians (Rein.), A. scrpentinus, Belemnites irregularis, Geotenthis Bollensis, Teu-
dopsis Schiebleri.
1. Lower Oolite.—(1.) Inferior Oolite.—Dysaster Ringens, C/ypeus Hugi ;
Rhynchone/la spinosa, T. fimbria, T. perovalis, lihynchonel/a spinosa ; Ostrea
Marshii, 0. acuminata, Pecten Lens, Trigonia costata, Pholadomya Fidicnla;
Turbo ornatus, Pleurotomaria granulata ; Ammonites Hiimphreysiaitns (fig. 730),
A. Parkinson!, A. Braikenridgii, Nautilus lineatus, Belemnites gigantens.
(2.) Great Oolite (Bath Oolite, including Stonesfield slate, Cornbrash and Forest
Marble).—A/iioeriuus Park!nsoni, A. elegans, C/ypeus Patella ; Terebratula digo-
na, Ostrea acuminata, Pecten Lens, P. vagans, Pholadomya gibbosa, Trigonia cos¬
tata ; Purpuroidea nodulata, Cylindrites acutus; Ammonites Discus, A. bullatus,
A. Braikenridgii, Belemnites gigantens; Megalosaurus Bucklandi, Teleosaur, Ce-
tiosaur, Pterodactyls, etc.
5. Middle Oolite.—(1.) Oxford Clay and Kclloway Rock.—Dysaster canali-
genera Cyrena, Planorbis, Limnsea, Unio, and Palndina. Fig. 743, Unio Vol-
dens is; 744, Yicipara [Palndina) Fluriorum.
3. Articulates.—Ostracoids, related to Cy- FiS- 745-
pris, etc., very abundant in some layers. Insects
of thirty or forty families, including Coleopters,
Orthopters, Ncuroptcrs, Ilemipters, and Diptors,
or Beetles, Crickets, Dragon-flies, Cicadae, May-
llies, etc.
4. Vertebrates.—Fishes of the orders of Ga¬
noids and Selachians, in all thirty or forty spe¬
cies. Reptiles.—Enaliosaurs of the genera Ich-
thyosaur and Pleslosaur; Dinosaurs of the genera
Igiianodon, Hyltxoartur, Megalosaur, Ftcgnosaur;
fig. 745, tooth of the Igiianodon; Crocodilians
with biconcave vertebra; of the genera Sucliosaur,
Goniopho!is, Poecilopleuron, etc., with convexo-con¬
cave vertebrae of the genus Cetiosaur, and also the
first of the concavo-convex, or procoelian, in species
of the modern genus Crocodilus; Pterodactyls;
Turtles, as the Tretosternum punctatum Owen(Tri-
onyx Bakcwelli Mantell), etc.
Iguanodon Mautelli.
JURASSIC PERIOD.
465
cnlatus, D. oralis; Terebralula diphya, Ostrea Marshii (fig. 723), 0. gregaria,
Gryplieea dilatata, Trigonia elongata, T. clavellata, Ammonites Jason, A. eorona-
tus, A. Calloviensis, Be/emnites hastatus.
(2.) Coral Limestone (Coral Rag).—Apiocrinus Royssianus, Hemicidaris crenu-
laris, Cidaris coronata, Pygaster patelliformis; Ostrea gregaria, Trigonia Bron-
nii, T. costata, Diceras arietina (fig. 728), Astarte elcgans, A. ovata, A. minima
(fig. 727); Nerin&a faseiata, N. Goodhallii; Ammonites Altenensis, A. plicatilis.
At Solenhofen, Pterodactyliis crassirostris (fig. 739), and other species.
6. Upper Oolite.—(1.) Kimmeridge Clay.—Ostrea dcltoidea, Exogyra Virgula
(fig. 724), Trigonia murieata, T. clavellata ? (fig. 726); Nerincea Gosce, Pteroeera
Occani; Ammonites decipiens, A. rotundas, A. biplex.
(2.) Portland Stone.— Ostrea expansa, Trigonia gibbosa, T. clavellata (fig. 726),
Lucina Portlandiea, Cardium dissimile, Uactra rostrata; Natica elegans; Am¬
monites biplex? A. giganteus.
7. Purbeck Beds.—Hemicidaris Purbeckensis; Ostrea distorta, Paludina
carini/era ; Cypris (various species); Mantellia megalophylla (fig. 673).
III. General Observations.
American Geography.—From the outcropping of the Jurassic
beds along the Black Hills and the flanks of the Rocky Mountains,
Hayden & Meek have inferred with good reason that these rocks
probably underlie the wide-spread Cretaceous strata of the eastern
slope of the Rocky Mountains ; and, as the elevation of the Rocky
chain above the ocean was not completed until long after the
close of the Cretaceous period (although it may have been begun
before it), we may infer that the condition mentioned as cha¬
racteristic of the Triassic period—a shallow submergence beneath
an inland sea (p. 442)—was followed in the Jurassic period by
a somewhat deeper submergence, or at least that the waters
communicated directly with the ocean, so that marine life once
more covered the Rocky Mountain region from Kansas westward
beyond the summit of the chain, and in these shallow seas lime¬
stones were forming again, as in the latter half of the Carboni¬
ferous age.
The absence of sea-shore Jurassic beds from the Atlantic border
leads to the same conclusions with regard to the coast in the Ju¬
rassic (period that were deduced for the Triassic (p. 442).
European Geography.—The Jurassic period commenced in
England with the marine deposits of the Lias. Through the Oo¬
lite the alternations were very numerous, indicating oscillations
between clear seas and shallow water or half-emerging land, in the
course of which there were coral reefs in England and Europe.
The evidences of shallow water and emerging flats increase to-
31
466
MESOZOIC TIME—REPTILIAN AGE.
wards the close of the period, dry-land intervals begin to predo¬
minate over the marine, and some parts of the Jurassic lands are
regions of lakes and estuaries, of forests, and of abundant Reptile
life. The history in Europe in part runs parallel with this, although
with many local peculiarities.
The position of the Jurassic beds across England on the east of
the older parts of the island, and their continuation over parts of
northern France, correspond with the view that they were formed
on the borders of a German Ocean basin. This is well shown as
relates to England on the map on p. 354. Whether there was
then a British Channel or not is not yet decided. Some English
geologists make the channel of Post-tertiary origin.
Life.—It is evident from the review that, while Conifers and
Cycads made up the bulk of the Jurassic forests,—Cestraciont and
other Sharks, Rays and Ganoids, the fishes of the world,—Trigonise,
Gryphaese, Ammonites, and Belemnites, a characteristic part of the
Mollusks,—at the same time grazing and carnivorous Dinosaurs
and Crocodilians, huge Swimming Saurians, Flying Lizards, and
Turtles, existed in vast numbers, and were the dominant inhabit¬
ants of the globe. Reptiles were pre-eminent in each of the three
elements,—in place of whales in the water, of beasts of prey and her¬
bivores on the land, and of birds in the air. It was the meridian of
the Reptile world. And the abundance and variety of the remains
in Britain seem to point to that region as one of the most populous
centres in the Reptile world.
Along with these powerful Reptiles, there were small Marsupials,
and probably Insectivores,—announcements of the decline of the
Reptile Age, and precursors of the reign of Mammals.
The great multitudes of Reptile and other remains entombed
in the Stonesfield slate, the Wealden, and the beds at Solenhofen,
do not indicate an excess of population about these spots. They
point out only the places where the conditions were favorable for
the preservation of such relics, and prove that the land was covered
with foliage and swarming with life, everywhere, we may believe,
as regards Insects, and at least in the vicinity of water for Reptiles.
A bed of coal is not proof of more vegetation than elsewhere, but
of the presence of fresh waters during the accumulation and
afterwards, which favored the kind of decomposition required for
making coal (see p. 361).
The dirt-bed of Portland, abounding in Mammalian remains, and
yet only five inches thick, shows strikingly what we should find in
the Coal formation, with its many scores of dirt-beds of far greater
thickness, if Mammals were then living.
CRETACEOUS PERIOD.
467
Climate.—The existence of Belemnitespaxillosus and Ammonites biplex
(or closely-allied species) in the Arctic, the Andes of South America,
and Europe, indicates a remarkable uniformity of climate over the
globe in the Jurassic period. No facts connected with the geogra¬
phical distribution of species are yet ascertained that sustain the
idea of a diversity of zones approaching the present. The facts
favor the view that the climate of the Arctic in the Jurassic period
was at least warm-temperate. See further, p. 738.
• CRETACEOUS PERIOD (18).
The Cretaceous period is the closing era of the Reptilian Age.
It is remarkable for the number of genera of Mollusks and Rep¬
tiles which end with it, and also for the appearance, during its
progress, of the modern types of plants and fishes.
The name Cretaceous is from the Latin cre.ta, chalk. The Chalk
of England and Europe is one of the rocks of the period.
1. AMERICAN.
Epochs.—1. Epocn of the Earlier Cretaceous • 2. Epoch of the
Later Cretaceous.
It is probable that only the later half of the Cretaceous period of
Europe is represented by these epochs in America.
I. Rocks: kinds and distribution.
The Cretaceous beds occur (1) at intervals along the Atlantic
border south of New York, from New Jersey to South Carolina, (2)
extensively over the States along the Gulf border, and (3) through a
large part of the Western Interior region, over the slopes of the Rocky
Mountains, from Texas northward, to the head-waters of the Mis¬
souri on the east of the summit of the chain, and far into the
Colorado region on the west. Still farther northwest in British
America, they appear on the Saskatchewan and Assiniboine,and
also on the Arctic Sea, near the mouth of the Mackenzie. North
of New York on the Atlantic border they are unknown.
On the map, p. 133, the Cretaceous areas are indicated by broken
lines running obliquely from the right above to the left below:
one area crosses New Jersey (the other outcrops on the Atlantic
border are too small to be indicated) ; a far more extensive area
covers the Gulf States, and another, the region west of the Mis¬
sissippi. The region along the Gulf border as well as Atlantic,
468
MESOZOIC TIME REPTILIAN AGE.
lined closely from the left to the right, is Tertiary ; and it pro¬
bably covers Cretaceous throughout. The part of the Rocky
Mountain region more openly lined in the same direction has a
surface of fresh-water Tertiary; but Cretaceous beds, in many
places at least, lie beneath.
The rocks comprise beds of sand, marl, clay, loosely-aggregated
shell limestone and compact limestone; they include in North
America no chalk.
The sandy layers predominate. They are of various colors,—white,
gray, reddish, dark green ; and, though sometimes solid, they are
often so loose that they may be rubbed to pieces in the hand, or
worked out by a pick and shovel. Layers of potter's clay occur in
the series.
The dark-green sandy variety constitutes extensive layers, and
goes by the name of Green-sand; and, as it is valuable for fertilizing
purposes and is extensively dug for this object, it is called Marl in
New Jersey and elsewhere. This Green-sand owes its peculiarities
to a green silicate of iron and potash, which forms the bulk of it,
and sometimes even 90 per cent., the rest being ordinary sand
mixed with it. There is a trace of phosphate of lime, evidently
derived from animal remains,—as animal membranes and shells
contain a small percentage of phosphates. It is supposed to owe
its value in agriculture to the potash and the phosphates. Fossil
shells are very abundant in many of the arenaceous and marly beds,
and in some they lie packed together in great numbers, as if the
sweepings of a beach, or the accumulations of a growing bed in
shallow waters, sometimes cemented together, but generally loose,
so as to be easily picked out by the fingers.
The Cretaceous limestones in Texas are firm and compact, and
some beds contain chert distributed through them, as the flint
through the Chalk of England.
The Cretaceous formation has a thickness in New Jersey of 400
to 500 feet ; in Alabama, of 500 to GOO ; in Texas, of about 800; and
in the region of the Upper Missouri, of 2000 to 2500 feet.
The two epochs, that of the Earlier and that of the Later Creta¬
ceous, are represented in the Western Interior region (including
Texas) ; while on the Atlantic and Gulf borders, in New Jersey,
and elsewhere, the beds, exclusive perhaps of the lowest unfossili-
ferous layers, belong to the Later Cretaceous.
The interior limit of the Cretaceous formation (see map, p. 133) follows a
line across New Jersey from Staten Island to the head of Delaware Bay;
across Delaware to the Chesapeake; across Maryland between Annapolis and
Baltimore, southwest into Virginia; occurs at Elizabeth on Cape Fear River in
CRETACEOUS PERIOD.
469
North Carolina, and sparingly in South Carolina. But more to the westward,
at Macon, Georgia, commences the large Southern Cretaceous region, which is
continued into the Mississippi basin, and whose inner outline passes by Columbus
in Georgia, Montgomery in Alabama, and then bends northward over north¬
western Mississippi towards the mouth of the Ohio; it descends southward
a^ain on the west side of the Mississippi over eastern Arkansas, spreading at
the same time westward south of Little Rock and Fort Washita; not far from
the last point the Cretaceous area expands southward over part of Texas, and
northward over a large part of the eastern slope of the Rocky Mountains, as
already mentioned. About the summits of the Rocky Mountains, Cretaceous
beds occur in New Mexico along the Rio Grande del Norte to its head-waters;
and west of the summit they spread over the region of the Colorado as far as
the meridian of 113° W.
On the Pacific coast, Cretaceous rocks have been found on the east side of Van¬
couver's Island, and on some neighboring islands; also, according to Whitney,
at various points in the Coast Range in California and along the foot-hills of the
Sierra Nevada, from Placer county to Shasta; they contain beds of coal on Van¬
couver's Island and in California; part of the California rocks are metamorphic.
As the Cretaceous formation is most fully represented in the region of the
Upper Missouri, a detailed section of it, by Meek & Ilayden, is here given, be¬
ginning below:—
1. Earlier Cretaceous.
1. Dakota (jroup.—Yellowish, reddish, and whitish sandstones and clays,
with lignite and fossil Angiospermous leaves: thickness, 400 feet. Lo¬
cation, near Dakota, and reaching southward into northeastern Kansas.
This division may require to be united with No. 2 (M. & II.).
2. Bmton group.—Gray laminated clays, with some limestone: thickness,
800 feet. Location, near Fort Benton, on the Upper Missouri, also below
the Great Bend; eastern slope of the Rocky Mountains.
3. Niobrara group.—Grayish calcareous marl: thickness, 200 feet. Loca¬
tion, Bluffs on the Missouri, below the Great Bend, &c.
2. Later Cretaceous.
4. Pierre group.—Plastic clays : thickness, 700 feet;—middle part barren of
fossils. Located on the Missouri near Great Bend, about Fort Pierre
and out to the Bad Lands, on Sage Creek, Cheyenne River, White River
above the Bad Lands.
5. Fox Hills group.—Gray ferruginous and yellowish sandstones and are¬
naceous clays: thickness, 500 feet. Location, Fox Hills near Moreau
River, above Fort Pierre near Long Lake, and along the base of Big
Horn Mountains.
In New Jersey, the beds and their relations to those of Nebraska are thus
stated by Meek & Ilayden from the observations of G. H. Cook :—
1. Earlier Cretaceous?.—No. 1? Bluish and gray clays, micaceous sand,
with fossil wood and Angiospermous leaves: thickness, 130 feet or more.
2. Later Cretaceous.—Nos. 4 and 5. (a.) Dark clays (130 feet), overlaid
by (5.) the first bed of Green-sand, 50 feet thick.—No. 5. («.) Sand colored
by iron, 60 to 70 feet; (5.) second bed of Green-sand, 45 to 50 feet;
(c.) yellow limestone.
470
MESOZOIC TIME REPTILIAN AGE.
In Alabama the formation consists of—
1. Earlier Cretaceous?—No. 1?. Dark-blue and mottled shales or clay,
with only vegetable remains; 300 feet or more.
2. Later Cretaceous.—No. 4. («.) Grayish and yellowish sand, often
obliquely laminated; 15 feet, (b.) Gray sand, with fossil shells; 6 feet, (e.)
Loose white sand, with shells ; 45 feet. No. 5. (a.) Soft white limestone, with
shells; 6 feet. (b.) Dark limestone ; 4 feet. (Winchell.)
In Texas the beds consist mainly of compact limestone, and the larger part
are of the Later Cretaceous. Shumard gives the following subdivisions:—
Marly clay, 150 feet, overlaid by arenaceous beds, 80 feet (Nos. 1 and 2).
(«.) Caprotina limestone, containing Orbitoliua Texana, etc., 55 feet; (5.) Blue
marl, 50 feet ; (c.) Washita limestone, 100 to 120 feet (No. 3). (d.) Austin
limestone, 100 to 120 feet (No. 4). (e.) Comanche Peak Group, 300 to 400 feet;
(/.) Caprina limestone, 60 feet.
Other localities of the rocks of the several subdivisions are as follow:—
No. 1, at different points in New Mexico (Newberry). No. 2, on the north
branch of the Saskatchewan, west of Fort a la Corne, lat. 54° N.; in New
Mexico (Meek). No. 3, over the region from Kansas through Arkansas to
Texas; in the Pyramid Mountain. No. 4, in British America, on the Sas¬
katchewan and Assiniboine; on Vancouver Island; Sucia Islands, in the Gulf
of Georgia. No. 5, at Deer Creek, on the North Platte, and not identified
south of this. (Meek & Haydcn.)
The Green-Hand beds of New Jersey, it is seen, belong to the Later Creta¬
ceous, while in Europe the earlier and the later Green-sand formations per¬
tain to the first half of the Cretaceous period, the part not yet known to be
represented in America. These Green-sand beds are, therefore, not confined
to a particular epoch, and of late have been found to occur even in the Paleo¬
zoic, and to be in progress in existing seas.
The green grains (called also Glauconite) consist of about 50 per cent, of
silica, 20 to 25 protoxyd of iron, 8 to 12 potash and soda (mostly potash),
and 7 to 10 water, with also a trace of phosphate of lime. For analyses,
see author's Treatise on Mineralogy.
The glauconite of the Chalk differs from that of the Lower Silurian rocks
of Canada (p. 176) in containing no alumina, the latter being a hydrous sili¬
cate of alumina and protoxyd of iron, with about 8. per cent, of potash.
(Hunt.)
n. Life.
1. Plants.
During the Cretaceous period there was a great change in thei
vegetation of the American continents. The Cycads of the Triassic
and Jurassic were accompanied by the first of the. great modern group of
Angiosperms,—the class which includes the Oak, Maple, Willow, and
the ordinary fruit-trees of temperate regions,—in fact, all plants
that have a bark, excepting the Conifers. More than one hundred
species have been collected, and half of them were allied to trees
CRETACEOUS PERIOD.
471
of our own forests,—the Tulip-tree, Oak, Dogwood, Beech, Poplar,
Willow, Alder, Button-wood, and Sassafras, or the genera Lirioden-
dron (fig. 747), Quercus, Cornus, Fagus, Pop id us, Salix (fig. 749), Alnus,
Plalanus, Sassafras (fig. 746), Liquidambar, Taxodlum, etc. These spe¬
cies have been collected in New Jersey, Alabama, Nebraska, Kansas,
New Mexico, and Vancouver's Island on the Pacific (Newberry), and
mainly from the earliest or Dakota group.
Besides Angiosperms, there were also the first of the Palms. It is,
however, still questioned whether any American Cretaceous speci¬
mens of this tribe have been found. Fossil palm-leaves of the fan-
palm kind (genus Sabal) are met with on Vancouver's Island, in
deposits which have been pronounced to be Cretaceous.
Fig. 746, Sassafras Cretaceum Newberry, from the Dakota group, along
with the three following (Meek & Hayden): fig. 747, Liriodendron Meekii
Figs. 746-749.
Angiosperms (or Dicotyledons).—Fig.746, Sassafras Cretaceum; 747, Liriodendron Meekii;
748, Leguminosites Marcouanus; 749, Salix Meekii.
Heer; fig. 748, Leguminosites Marcouanus Ileer; fig. 749, Salix Meekii
Newberry.
472
MESOZOIC TIME REPTILIAN AGE.
Largo stumps of Cycads have been found in Maryland near Baltimore; one is
12 inches in diameter and 15 high. (P. T. Tyson, who observes that they may
be Upper Jurassic.)
2. Animals.
Among Protozoans, the group of Rhizopods has a special im¬
portance in the Cretaceous period. They are abundant in many
of the beds in New Jersey and other Cretaceous regions of North
America, though less so than in the chalk beds of Europe. In one
genus, Orbitolina, the species are disk-shaped (fig. 750), and closely
resemble in form some of the Nummulites of the early Tertiary.
Sponges also are a common fossil, although little known thus far
in America.
In the sub-kingdom of Mollusks, the more characteristic genera
of Conchifers are the three of Oysters, Ostrea (fig. 753), Gryphcea
(figs. 755, 750), and Exogyra (fig. 754) (species of which occurred
in the Jurassic period, but are more common and larger in the
Cretaceous), and Inoccramus (fig. 757), a genus belated to Avicula
and Mytilus, some species of which are of great size and have the
surface in undulations. Exogyra and Inoccramus end with the Cre¬
taceous, and but one Gryphcea is known afterward.
Another group characteristic of the Chalk period, and, moreover,
not known after it, is that of the Rudistcs (figs. 782-784). It includes
the genera Ilippurites, Radiolitcs, Sphcrulitcs, and a few others, llip-
puritcs has a long tapering form (fig. 782), somewhat like a nearly
straight, but rude, horn with a lid on the top, the lid being the
upper valve, and the conical portion the lower. Within there is
a subcylindrical, tapering cavity, having one or more projecting
ridges on the sides running the whole length. Fig. 782 a shows the
interior of one: there are two prominent ridges, but one is only
partly free in the interior space. The other genera have a similar
anomalous character, but differ in the interior. Fig. 788 repre¬
sents the lid or upper valve of a Radiolitcs, showing the projections
below (b, c) to which the muscles closing the lid are attached; and
fig. 784 is the same in Sphcrulitcs. The Rudistes are supposed to be
related to Chama among the Dimyary Mollusks.
Of Ceplialopods, there are in the Cretaceous beds numerous Am¬
monites and Belemnites. Some of the Ammonites from beyond the
Mississippi are over three feet in diameter. There is also a multi¬
plication of other genera of the Ammonite family, the shells of
which are like Ammonites more or less uncoiled; as Scaphites (figs.
766, 767), from scapha, a boat; Crioceras (fig. 786), from npioq, a ram's
horn; Ancyloceras (fig. 787), from aysvAy, a hook or handle; Hamites,
CRETACEOUS PERIOD.
473
(fig. 783), from hamus, a hook; Toxoceras (fig. 789), from to^ov, a how;
Baculitcs (fig. 708), from baculum, a walking-slick. Turrilitcs (fig.
790) is another form, unlike other Ammonitids in being a turreted
spiral. Another genus resembles an opened spiral, and is called Heli-
coccras. Among these genera, only Ammonites, Scaphitcs, Ancgloccras,
Hamitcs, Ptychoccras, Baculites, Turrilites, and Ilclicoceras, have been
found in American Cretaceous rocks. Baculitcs ovatus (fig. 708)
attains a length of a foot or more, and a diameter of 2h inches,
and iScapkites Conradi (fig. 700) a length of six inches. Ancyloceras
and Toxoceras occur first in the European Jurassic.
Among Vertebrates, there is the first appearance of several pro¬
minent modern groups, marking grand steps of progress in the
life of the world. The most prominent is that of
Common or Osseous Fishes, or Tcliosts,—the tribe which includes
nearly all fishes, excepting Ganoids and Sharks, and, consequently,
nearly all edible species. Their distinguishing characteristics are
mentioned on page 278.
Besides this mark of progress, there are many other new genera
of Fishes, and several of Reptiles.
The Squalodonts, or modern tribe of Sharks, having teeth with
sharp cutting edges besides other peculiarities, are greatly multi¬
plied. The new tribes do not displace the Cestracionts and Ga¬
noids, which continue to be common until the close of the Creta¬
ceous period, and still have some representatives.
Figs. 772, 773, represent some of the Sharks' teeth. Fig.
773 are pavement-teeth of a fish of the old Cestraciont group,
pertaining to the genus Ptychodus, characteristic of the Cretaceous
period.
Beyond the Mississippi, remains of Reptiles have been found,
and both there and in New Jersey bones of a colossal Lacertian
Reptile of the genus Mosasaurus. These Reptiles are supposed to
have been web-footed and aquatic in habit, while at the same time
carnivorous. The tail was flattened, long, and powerful, and thus
fitted for sculling through the water. The New Jersey species was
24 feet long. Another large Reptile, Iladrosaurus Foulkii Leidy, is
related to the Iguanodon of the Wealden, and was probably 25
feet long; its remains were found near Iladdonfield, N.J.
474
MESOZOIC TIME REPTILIAN AGE.
Characteristic Species.
1- Protozoans. Rhtzopods.— Textilaria Missouriensis, T. globulosa, Pha-
uerostomum senarium, Rotalia lenticulina, It. senaria, Grammostomum phyllod.es,
Figs. 750, 751 A, B.
Rhizopod.—Fig. 750, Orbitolina Texana. Brachiopods.—Fig. 751 A, Terebratulina plicata;
751 B, Terebratula Ilarlani.
from the Cretaceous of the Upper Missouri, identified by Ehrenberg; Cristel-
laria rotulata, Dentalina pit/chrci Gabb, etc., from New Jersey; fig. 750, Orbito¬
lina Texana Roemer, from Texas, a species having the form of a disk, slightly
conical.
2. Radiates.—(a.) Polyp-Corah.—Astroccenia Sancti-Sabie Roemer, Texas;
Montlivaltia Atlantica, New Jersey, etc.
(b.) Bellinoderms.—Ihdaster simplex; Ananchytes cinetus, Toxaster elegans;
also species of Diadema, Hemiasler, Holectypns, Cyphosoma, etc.
3. Mollusks.—(a.) Bryozoans.—Numerous species have been described
and figured by Gabb & Horn, of the genera Jlembranipora, Flmtrella, Escha-
ripora, Bijlustra, etc.
(b.) Brachiopods.—Fig. 751 A, Terebratulina plicata ; fig. 751 B, Terebratula
Harlani Morton, from New Jersey; Lingula nitida M. & II., Nebraska.
(c.) CoHchifem.—Fig. 753, Ostrea Larva Lamarck, found also in Europe; 0.
con g est a. Conrad, from Arkansas and Nebraska; fig. 752, Exoyyra arietina
Roemer, from Texas; fig. 754, E. costata Say, from the Cretaceous of the Atlan¬
tic and Gulf borders; fig. 755, Gryphce.a vesicularis Lamk., at nearly all North
American localities, and also a European species; fig. 756, G. Piteheri Morton,
from Cretaceous region west of the Mississippi River; fig. 757, Inoceramus pro-
blematicus Schlotheim, from west of the Mississippi, and also a European species.
Among Rudistes, Radiolites Aiistinensis Roemer, a species five to six inches
in diameter, from Alabama, Mississippi, and Texas; Radiolites lamellosut
CRETACEOUS PERIOD.
475
Tuomey, from Alabama ; ffippurite* Texan nn Roemer, a species eight inches long
and four in diameter, from Texas; Cnprotiua Texana ltoemer, from Texas.
Figs. 752-757.
Conchifees.—Fig. 752, Exogyra arietina; 753, Ostrea Larva; 754, Exogyracostata; 755, Gry-
pheea vesicularis; 756, G. Pitcheri; 757, Inoceramus problematicus.
Figs. 758-764.
Sasteropods.—Fig. 758, Fusus Newberryi; 759, Fasciolaria huecinoirles; 760, Aporrhais
Americana; 761, Margarita Nebrascensis ; 762, Neriuasa Texana; 763, 764, Bulla speciosa.
476
MESOZOTC TIME—REPTILIAN AGE.
Figs. 765-770.
Cephalopods.—Figs. 765, 765 a, 765 5, Ammonites Placenta; 766, Scaphites Conratli; 767, S.
larva?formis; 768,768 a, Baculites ovatus; 769, Section of B. compressus, reduced; 770,
Nautilus Dekayi.
CRETACEOUS PERIOD.
477
(d.) Gasteropoda.—Fig. 75S, FususNewberryi M. & II., from Nebraska; fig. 759,
Fasciolaria biiccinoiiles M. & H., from Nebraska; fig.760, Aporrhais? Americana
(= Jlostellaria Americana) Evans & Shumard, from Nebraska; fig. 761, Mar¬
garita Nebrasccnsis M. & II., from Nebraska; fig. 762, Neritieen Texautt lloemer,
from Texas; N. Acus Rocmer, from Texas; figs. 765, 764, Bulla speciosa
M. & II., from Nebraska.
(e.) Cephalopoda.—Fig. 765, Ammonites Placenta Dekay, from Atlantic border,
Gulf border, and Upper Missouri, young specimen, natural size; fig. 765 a, out¬
line side-view of the same, reduced; fig. 765 5, one of the septa of the same,
natural size ; fig. 766, Scaphitex Conradi Morton, from the same localities as pre¬
ceding; fig. 767, S. lurvnformis M. & II., from Nebraska; fig. 768, Baculitcs
oca tux Say, from New Jersey; fig. 768 a, outline of section showing oval form;
fig. 769, outline of section of B. compressus Say, Upper Missouri; fig. 770, Nau¬
tilus Dclcayi Morton, from the Atlantic and Gulf borders, and west of the
Mississippi from Texas to Upper Missouri, and also reported from Europe,
Chili, and Pondicherry in the East Indies. Fig. 771, Belemnitclla mucronata
Schlotheiin, same U. S. distribution as preceding.
Fig. 771.
Cephalopod.—Belemnitolla mucronata.
4. Vertebrates.—(«.) Fishes.—Fig. 772, Otodus appendiculatns, from New
Jersey. This genus Otodus (of the tribe of Squalodonts) is near Carcharodon,
Figs. 772, 773.
Squalodont Selacxiiax.—Fig. 772, Otodus appendiculatns. Cestraciont Selachian.—
Figs. 773, 773 a, Ptyeliudus Mortoni.
but the teeth have a smooth margin without dcnticulations. Oxyrhina, an.
other genus of this period, is like Otodus in this respect, but wants the smail
lateral teeth a, a. There were also species of Lanma, the teeth of which are
478
MESOZOIC TIME REPTILIAN AGE.
narrow, as in fig. 405, page 277. Figs. 773, 773 a, different views of a tooth
of Ptychodus J fort on i (Cestraciont), a species found in New Jersey.
(b.) Reptiles.—Jfosasaurua Jlaximihaui Goldfuss, from New Jersey, a species
24 feet long: a fine specimen of the cranium is in the Museum at Bonn in
Prussia. Fig. 774, Crocodilus clavirostris Morton, from New Jersey: whole
Fig. 774.
Crocodilus clavirostris ( X Yc )•
length of skull (in specimen) 23 inches, greatest breadth 12J inches. Owen
has named two other New Jersey Crocodiles, C. basiftssm and C. basitruncatns.
Remains of the Geosaur, according to Morton, occur in New Jersey; also bones
of Turtles.
(c.) Mammals.—None. The species of Priscodelphinus Leidy, from New Jer¬
sey, supposed to be Cretaceous, are now known to be Tertiary.
III. Fossils characteristic of the Subdivisions of the Creta¬
ceous.
A. Earlier Cretaceous.—No. 1 (Dakota group). Upper Missouri: Pha-
rcl/a ? Dakotensis, Ax i wen Siouxensis, Cyprina arenaria, Leaves of Angio-
sperms. Alabama: Cera tiles ? Americanus Harper, Leaves of Anjiosperma.
Now Jersey : Leaves of Angiospasms.
No. 2 (Benton group). Upper Missouri: Inoceramus problematicus, I. um-
bonatus, Ostrcn congesta, Pholadomya papyracea, Ammonites percarinatus, A.
vespertinus Morton (= A. Texanus Roemer), Seaphitcs larvstformis. Texas:
Ammonites percarinatus, fnoceramits Capulus. New Jersey: none.
No. 3 (Niobrara group). Upper Missouri: Ostrcn congesta, Tnoceramus pro¬
blematicus, I. aviculoides, I. pseitdo-mytiloides. Arkansas : To.vaster elegans,
Ilolaster simplex, Cardium multistriatum, fnoceramits problematicus, I. confertim-
annulatns, GrypJnra Pitclicri. Texas: Holaster simplex, Epiastcr elegans, Cidaris
hemigrannsus, Gryphxa Pitclicri, Ostrea subovata (0. Marshii Jfarcoii), Iiwceramus
problematicus, Turrilites Rrazocnsts, Ammonites Texanus, Hamites Fremonti.
New Jersey: none.
CRETACEOUS PERIOD.
479
B. Later Cretaceous.—No. 4 (Pierre group). Upper Missouri: Nautilus
Dekayi, Ammonites Placenta, A. complexus, Baculites ovatus, B.compressus, Heli-
coceras Morloni, Inoeeramus sublevis, Mosasaurus Missouriensis. Alabama:
In bed a, Teredo tibialis?; in bed b, Exoyyra costata, Gryphxa vesieularis,
Inoeeramus biformis, Pccten b-costatns, Nautilus Dekayi, Ammonites Placenta,
A. Delawcirensis, Baculites ovatus; in bed c, Ostrea Larva, Gryphxa lateralis
(G. Vomer), Neithca Mortoni. New Jersey: Bed a, Ammonites Placenta, Bacu¬
lites ovatus; bed b, Amm. Delawavcnsis, A. complexus, Baculites ovatus, Nautilus
Dekayi, Bclemnitella mucronata; bed c, Tcrebratuliua plicata, Pholadomya
occidentalis, Ostrea Larva, Gryphxa vesieularis, Exoyyra costata, bones of Mosa¬
saurus.
No. 5 (Fox Hills group). Upper Missouri: Nautilus Dekayi, Amm. Placenta,
A. lobatw, Seaphitcs Conradi, Baculites ovatus, Mosasaurus Missouriensis.
Alabama: Exoyyra costata, Gryphxa vesieularis, Nautilus Dekayi, Baculites
ovatus, Seaphitcs Conradi. New Jersey: Montlivaltia Atlantica, Nucleolites
erucifer, Ananchytes ductus, A. fimbriatus, Terebratula Hurlani, Gryphxa lateralis,
G. vesieularis, Neithca Mortoni.
The New Jersey region abounds in Oysters and Exoyyrx, has some Ammonites,
Baculites, and Echinoderms, but no Hippurites or Caprinx.
The Upper Missouri has very few Oysters, no Exoyyrx, many and large Am¬
monites and Baculites, but one rare Echinoderni (Hcmiaster Hnmphreysianus), no
Brachiopods, except two Linyulx, and no Hippurites or Caprinx.
The Alabama resembles the New Jersey, and the Arkansas the corre¬
sponding or middle beds of Nebraska and upper of New Jersey; but both con¬
tain Hippurites and Echinoderms.
The Texas region has but few species in common with the others,—Ammonites
oespertinus, Inoeeramus latus?, and/. Bambini, the latter being still questioned;
and it is characterized by Hippurites, Caprinx, Nerinxx, etc., like the Upper
Chalk of southern Europe.
The species common to Nebraska and New Jersey, according to Meek & ITay-
den, are Nautilus Dekayi, Seaphitcs Conradi, Ammonites Placenta, A. complexus,
A. lobatus, Baculites ovatus, and Amauropsis paludinxformis.
2. FOREIGN.
I. Rocks : kinds and distribution.
The Cretaceous formation covers a large part of southeastern
England eastward of the limit of the Jurassic, from Dorset on the
British Channel to Norfolk on the German Ocean ; and also a nar¬
row coast-region about, and south of, Flamborough Head. (Map p.
354.) Like the Jurassic, it reappears again in northern France,
across the British Channel. It also occurs in other parts of France,
in Sweden, and in southern, central, and western Europe.
The rocks are (1) Sandstone, generally soft, and of various colors;
(2) Marly or clayey beds; (3) the variety of limestone called
Chalk, the common writing-material, in beds of great thickness;
480 MESOZOIC TIME—REPTILIAN AGE.
(4) other limestones, either loose or compact. Among the sandy
portions the Green-sand beds are a marked feature, especially of
the lower part of the formation. This is so eminently the fact
that the Lower Cretaceous in England is called the Green-sand,
although only a part of the layers are green, and in some regions
none at all.
The Chalk often contains flint in nodules, which are distributed
in layers through it like the liornstone in the earlier limestones.
They are more or less rounded, and often assume fantastic shapes.
Sometimes they resemble rolled stones; but in fact all are of con¬
cretionary origin. The exterior of the nodules for a little depth
is frequently white, and penetrated by chalk, proving that they are
not introduced boulders or stones, but have originated where they
lie. Moreover, many chalk fossils are turned into flint, and it is
common to find a mass of flint with a fossil as its nucleus.
The Cretaceous beds of Europe have been divided into—
1. The Lower Cretaceous, including in England the Lower Green-sand, 800
to 900 feet thick, and in other regions beds of clay, and limestone sometimes
chalky.
2. The ifiddle Cretaceous, including in England (a) the clayey beds or marls
called Gault, 150 feet thick, and (b) the Upper Green-sand, 100 feet.
3. The Upper Cretaceous, including in England the beds of Chalk, in all about
1200 feet: it consists of (a) the Lower or Gray Chalk, or Chalk Marl, without
flint; (b) the While Chalk, containing flint; (e) the Maestricht beds, rough friable
limestone at Maestricht in Denmark, 100 feet thick.
The subdivisions of the Cretaceous are variously named in different parts of
Europe.
Lower Cretaceous.—Superior Neoomian of D'Orbigny (the Wealden being
the inferior); also his Aptian ; the Ilils-conglomcrat of Germany.
Middle Cretaceous.—1. Gault, Albian of D'Orbigny, Lower Pliinerkalk of
Saxony.—2. Upper Green-sand, Ccnomanian of D'Orbigny, Lower Quadersand-
stein of the Germans.
Upper Cretaceous.—1. Gray Chalk, or Chalk without flints, Turonian of
D'Orbigny, Ilippurite Limestone of the Pyrenees, Upper Pliinerkalk of Saxony.
2. White Chalk, or Chalk with flints, Senonian of D'Orbigny, Upper Quader-
sandstein? of the Germans, La Scaglia of the Italians. 3. Maestricht beds,
Danian of D'Orbigny, Calcaire pisolitique near Paris.
In North America the Earlier Cretaceous corresponds, according to Meek &
Ilayden, to the inferior division of the Upper Cretaceous of Europe, or the Gray
Chalk, with perhaps part or all of the Middle Cretaceous; and the Later Creta¬
ceous, to the superior division of the Upper Cretaceous, or the White Chalk.
In mineral character the beds of each division vary much over Europe, the
Chalk of England being synchronous with marls and solid limestones in Europe.
The Cretaceous of Great Britain is not found on any part of the Atlantic
coast, excepting a small area in the vicinity of the Giants' Causeway. The beds
of northern France spread eastward over Belgium and Westphalia, but not to
CRETACEOUS PERIOD.
481
the Atlantic on the west; but farther south they occur at the deep indentation
of the Bay of Biscay. They cover part of the Pyrenees, and reach into Spain
in what has been called the Pyrenean basin, which in the Cretaceous period was
a bay on the Atlantic. There is another sea-border deposit at Lisbon, in Spain.
In southern France, over what is called the Mediterranean basin, the beds ex¬
tend from the Gulf of Lyons along the Mediterranean coast, northeast to Swit¬
zerland, though with interruptions. The formation is found in the Juras and
Alps, in Italy, Savoy, Saxony, Westphalia and Bohemia, northern Germany,
Poland, middle and southern Russia, Greece, and other places in Europe. In
Asia it has been observed about Mount Lebanon and the Dead Sea, the Cauca¬
sus, in Circassia and Georgia, and elsewhere; in northern and southern Africa;
in South America, along the Andes, and on the Pacific coast, occurring in
Venezuela, in Peru, at Concepcion in Chili, in the Chilian Andes at the passes
of the Portillo and Rio Volcan at an elevation of 9000 to 14,000 feet, in the
Straits of Magellan at Fort Famine in Fuegia.
II. Life.
The Life of the Cretaceous period in Europe resembled that of
America, but was far more abundant. Nearly 0000 species of ani¬
mals have been described, more than half of them Mollusks;
whereas in America the whole number does not exceed 2000.
1. Plants.
Angiosperms and Palms were growing in Europe, and among the
former there were the Willow, Walnut, Maple, and Holly. But
the relics of Ferns, Conifers, and Cycads greatly preponderate; for
the Cretaceous was properly the closing part of the era of Cycads.
Vegetable remains of all kinds are rare, as the deposits are marine.
The microscopic Protophytes called Diatoms and Desmids are
found in some of the beds, especially in the flint of the Chalk.
The former have siliceous cases, as explained and illustrated on
p. 271, and they may have contributed, as has been suggested, to
the material of the flint nodules. The Desmids are not siliceous,
but are still very common in the flint,—far more so than Diatoms
(which are rare): the kinds which have been called Xanthidia are
especially abundant; their forms are very similar to those from
Tie Devonian hornstone figured on p. 271.
2. Animals.
The Protozoans of the family of Rhizopods (p. 163) appear to have
been among the most important rock-making species of the Creta¬
ceous period ; for it is supposed that the Chalk itself is to a large
extent made of their shells. According to Ehrenberg, a cubic inch
32
482
MESOZOIO TIME—REPTILIAN AGE.
of chalk often contains more than a million of microscopic organ¬
isms, among which far the most abundant are these Rhizopods
(called also Foraminifera and Polythalamia). Some of the species
are represented in figs. 778-781.
The Sponges, also, were of great importance in the history of the
Cretaceous rocks. They occur cup- or saucer-shaped, tubular,
branched, and of other forms. One is figured in fig. 777. Their
Fig. 776.
Spicula of Sponges.
siliceous spicula are common in the flint, and have contributed, as
well as Diatoms, towards the silica of which it was made.
Among Radiates, the Corals and Echinoids are mostly of modern
types, and are far more numerous than in the Cretaceous of
North America.
The same genera of Mollusks abound that are enumerated on
p. 472. But the variety of Brachiopods, Gasteropods, and Am¬
monites is vastly greater than on the American continent. The
Ammonites, and the uncoiled forms of the same family mentioned
on p. 472, are particularly abundant. One English Ammonite
(the A. Lewesiensis), from the Lower Chalk, has a diameter of a
yard.
The genera of Gasteropods are to a greater extent modern
genera than in the preceding period, and the proportion of siphon-
ated species (having a beak) is nearly as great as in existing seas.
The Ruclistes (figs. 782-784) are very common in southern Europe
and Asia Minor, and about eighty species have been described; only
a single species—Radiolitcs Mortoni—has been found in England.
In the sub-kingdom of Vertebrates, there are Fishes of the mo¬
dern order of Teliosis, and Sharks of the modern tribe of Squalo-
donts, as stated with regard to America (p. 473). One of these
new fishes of the former group is shown in fig. 791. The Salmon
and Perch families are represented among these earliest of Teliosts.
Cestraciont teeth are very common.
The class of Reptiles in the earlier part of the Cretaceous period
included the Iguanodon; both then and later there were three or
four Plesiosaurs ; an Ichthyosaur; another swimming Saurian, called
Polyptychodon by Owen, nearly 50 feet long; several Pterodactyls, one
of which, the P. yiganteus, was 6 to 7 feet in the spread of its
wings ; a Mosasaur, 25 feet long (fig. 792); some Turtles. No true
CRETACEOUS PERIOD.
485
Crocodiles have been reported from the European Cretaceous beds.
No remains of Birds or Mammals have yet been discovered.
Characteristic Species.
1. Protozoans.—(a.) Sponges.—Fig. 777, Siphonia lobata, from the Chalk.
Fin-s. 770 a to 776 h represent the siliceous spicula of Sponges, showing some
of the various forms they present. Over
one hundred species related to Sponge occur
in the Cretaceous strata of England. Scyphia,
Spongia, and Ventriculites are the more
common genera among the twenty enume¬
rated.
(b.) Rhizopods.—Fig. 778, Lituola nauliloi-
dea. Fig. 779, Flabellina rugosa; fig. 779 a,
profile of same. Fig. 780, Chrysalidina gra-
data. Fig. 781, Cuneolina Pavonia ; fig. 781 a,
profile of same. All are much magnified, the
species being very minute, not exceeding half
a line in length. Other genera are Rotalia,
Textilaria, Nodosaria, etc. The Chalk formation of England has afforded over
one hundred and twenty species and between twenty and thirty genera, and
Figs. 778-781,
f
Rhizopods.—Fig. 778, Lituola nautiloidea; 779a, Flabellina rugosa; 780, Chrysalidina gra-
data; 781, a, Cuneolina pavonia.
among them two species of the genus Orbitolina, an American species of which
is represented in fig. 750.
2. Radiates.—(a.) Polyp-Corals.—Species of Cyathina,Trochocyathus, Tro-
chosmilia, Parasmilia, Micrabacia (formerly Fungia), etc.
(ft.) Echinoderms.—Species of the genera Ananchytes, Cidaris, Diadema, Cy-
phosoma, Hemiaster, Cardiaster, Gdlerites, Holasler, Micraster, etc.
3. Mollusks.—(a.) Bryozoans.—Genera Esehara, Escharina, Vineularia,
Flnstra, Cricopora, etc.
(ft.) Brachiopods.—Numerous species of Terebratula, Tercbratella, Terebra-
tulina, Rhynchonella, Crania, Thecidia, etc.
('•'.) Conchifers.—Species of Gryplixa, Exogyra, Inoceramus, Gervillia, Trigo-
nia,—all extinct; also of Cardium, Astarte, Cardita, Corbula, Isocardia, Lima,
Fig. 777.
Siphonia lobata.
484
MESOZOIC TIME REPTILIAN AGE.
Crassatclla, Cypnna, Cytherca, Venus, Lueiiia, Panopira, Avieulct, Pectcn, Neithea,
Pho/as, Spondylus, Te/lina, Plica tula, and many other genera of existing seaa
Figs. 782-785.
Coxchifers, Budistes Family.—Fig. 782, Ilippurites Toucasianus; 782a, II. dilatatus; 783,
Radiolites Bournoni; 784, Spherulites Iloeningshausi. Gasteropods.—785, Nerinaea bisui-
cata; 785 A, Avellana Cassis.
which give a modern aspect to a conchological cabinet of the Cretaceous period.
The genera Crassatella and Neithea commence with the Chalk. Among the spe¬
cies of the extinct tribe of Rudistes, fig. 782, Hipp>urites Toucasianus, from the
Upper Cretaceous, one of the most common species of southern Europe; fig.
782 a, H. dilatatus, vertical view, showing the interior of the lower conical valve,
from the Lower Cretaceous ; fig. 783, Radiolites Bournoni, upper valve in profile,
from the Upper Chalk; fig. 784, Spherulites Hoeningshausi, upper valve in pro¬
file, from the Upper Chalk ; h, c, in 783, 784, attachments of muscles.
(d.) Gasteropods.—The extinct genera Nerinxa, Aetxonina, Actxonella, Avel¬
lana, etc. The modern genera Stkombus, Busycon, Buccinum, Fusus, Vo-
luta, Oliva, Fasciolaria, Ovula, Cypr^A, Trochus, Nerita, Natica, Mitra,
Con us, Cerithium, Bulla, etc., showing a striking approximation to the present
age in the closing period of the Mesozoic. (The genera in small capitals are
some of those which make their first appearance in the Cretaceous period.)
Fig. 785, Nerinxa hisulcata d'Archiac, from the White Chalk. Fig. 785 A, Avel¬
lana Cassis, from the Upper Green-sand; a, outline sketch, showing the toothed
aperture.
CRETACEOUS PERIOD.
485
(e.) Cephalopods.—Tetrabranehs (or Tentaculifcrs) of tho Ammonite and Nau¬
tilus families.—Fig. 7S6, Crioceras Duvalii, from the Lower Cretaceous. Fig. 7S7,
Figs. 7S6-790.
Cephalopods, Ammonite Family.—Fig. 786, Crioceras Duvalii; 787, Ancyloceras Matberoni-
anus; 788, Ilamites attenuatus; 789, Toxoceras bituberculatus; 790, Turrilites catenatus.
Ancyloceras Mathcronianus, Lower Cretaceous. Fig. 78S, Ilamites attenuatns,
Middle Cretaceous. Fig. 789, Toxoceras bituberculatus. Fig. 790, Turrilites
catenatus, Gray Chalk. Also Baculites (as B. auceps, etc.).—Dibranchs (Aceta¬
bulars): Belemnitella mucronata, a common species of the Upper Cretaceous;
also species of Belemnites and Conoteutliis.
4. Articulates.—Worms of several genera. Crustaceans, of the Brachy-
ural genera, Grapsus, Podoph th aim us, Podopilumnus, Area nut, Notopocoryst.es,
etc.; and the Macroural, ScyUarus, Callianassa, Palceastacus, etc. Of the tribe
of Cirripeds, Tubicinella, Pollicipcs. Also Ostracoids.
5.Vertebrates.—(«,) Teliost Fishes.—Fig. 791, Osmeroides Lewesiensis, from
the Chalk at Lewes,—a fish of the Salmon family (Cycloid) related to the Smelt
(genus Osmerus), and about fourteen inches in length. Another species of the
genus, from the same beds, 0. Mantelli, is eight or nine inches long. There were
other Cycloids, of the genus Clnpea (Herring), etc. Several species of Beryx,
a genus related to the Perch (Ctenoid), occur in the Chalk: one, B. Lewesiensis,
486
MES0Z01C TIME—REPTILIAN AGE.
is a broad fish, six to twelve inches long; another, B. snperbus, sometimes thir¬
teen inches long. About twenty-five genera of Cycloids and fifteen of Ctenoids
Fig. 791.
MMPi
Teliost.—Osnieroides Lowesicnsis ( X '/£ )■
have thus far been recognized in the Cretaceous. Ganoids were numerous in
species, of the genera Belonostomns, Caturus, Lepidotm, etc., besides others of
the Pycnodont family, Pycnodus, Gytodus, etc. Sharks of the Ilybodont
family were sparingly represented; Cestraeiont remains were very common, es
pecially of the genera Ptychodus and Acrodus. Teeth of Squalodonts are occa¬
sional!}' met with, of the genera Carc.liarias, Lamna, Oxyrhina, Odontaspis, etc.
b. Reptiles.—Fig. 792, Moxusuurus Hofmnnni, head, from the Chalk at Maas¬
tricht, one-eighteenth the natural size. Other remains of this species have been
Fig. 792.
Mosasaurus Ilofmanni (X A )•
found at Lewes in England. In general character it is related to the Lizards;
but the short and stout humerus has led to the suggestion that it may have been
a swimming species, and therefore a wholly new type.
CRETACEOUS PERIOD.
487
Leiodon, Raphiosanrus, and Coniosaurus arc other genera of the Upper Cre¬
taceous. The genera Ichthyosaurus, Plesiosaurus, and Pterodaetylus reach even
into the Upper Cretaceous: lyuanodon occurs only in the Lower.
Species of wide geographical distribution.
The following species aro
Ostrea Larva,
Gryphxa vesicidaris,
Exoyyra leviyata,
Exoyyra Boussiuyaultii,
Inoceramus Crispii,
Inoceramus latus,
Inoceramus mytiloidcs,
Ncithea Mortoni,
Pecten circulans,
Triyonia limbatus,
Triyonia aliformis,
Triyonia lonyus,
Hipp u rites orya n isa lis,
Nerinxa bisulcala,
Baculites aiiceps,
Ammonites vespertinus,
reported from different continents (Bronn) :—
N. A.; Eu.; India.
N. A.; Eu.; S.W. Asia.
Eu.; Columbia, S. A.
Eu.; Columbia, S. A.
N. A.; Eu.
N.A.; Eu.
N.A.; Eu.
N. A.; Eu.; India; Peru, S. A.
N. A.; Eu.; India; Peru, S. A.
N. A.; Eu.; India.
N. A.; Eu.; S.W. Asia; Columbia, S. A.
Eu.; Columbia, S. A.
Eu.; S.W. Asia; Peru and Chili, S. A.
N. A. (Texas); Eu.
N. A.; Eu.; Chili, S. A.
N.A.; Eu.
The following Ammonites, according to D'Orbigny, are common to Europe
and South America:—A. Boyotensis, A. Dumasianus, A. Didayanus, A. yaleatus,
A. Vandee/ci, A. Tctlnjs, A. prerlonya, A. simplex, besides others. The Echinus
Toxaster complanatus is said to have the same range.
Relations of the Earlier and Later Cretaceous of America to the
corresponding divisions of Europe.
The following tables of species in the Earlier and Later Cretaceous of Ame¬
rica, showing their relations to species of the corresponding divisions in
Europe, are from a paper by Meek & Ilaydcn :—
Earlier Cretaceous W. of Miss. R. Lower or Gray Chalk in Europe.
occurs in Austria.
probably ident. with A. Woolyari Mantell.
scarcely distinct from S. tcqualis Sowerby.
same type as S. ivqualis.
scarcely distinct from N. clcyans Sowerby.
appears to be the same as I. latus Mantell.
cannot be distinguished from I.problematicus
Schlot.; reported also from the Upper
Green-sand of Europe.
Species common to the Later Cretaceous of America and the Upper or White
Chalk of Europe:—Eauroccphalus lanciformis, Lamna acuminata, Belenniitella
mucronata, Ncithea Mortoni, Ostrea Larva, Gryphxa lateralis, Gryphxa vesicu-
Ammonites vespertinus Mort.
A. pcrcarinatus H. & M.
Scaph'.tes Warren i J/. & II.
S. larvajforinis M. & II.
Nautilus elegans, var.
Inoceramus latus ?
I. problematicus
488
MESOZOIC TIME—REPTILIAN AGE.
laris, Nucleolites crucifcr. The Gryphsea vesicularis is supposed by some to occur
also in the Upper Green-sand and the Lower or Gray Chalk, but the form found
in these lower portions is regarded by other authorities as a distinct species.
Genera of the Later Cretaceous of America not yet found below the White
Chalk of Europe :—Mosasaurus, Saurocephalus, Callianasna, Pleurotoma, Fascio-
laria, Cypruca, Pulvinites, Cassidulus. There are also in the American Later
Cretaoeous the three genera, Pneudobuccinnm, and Xylophaga? which have not
yet been found as low as the Cretaceous in Europe.
III. General Observations.
1. Origin of the Chalk and Flint.—From the absence of vegetable
remains and earthy ingredients, the abundance of sponges, and the
general character of the fossils, it is supposed that the Chalk was
formed at a distance of some miles from shore, where the water
was at least 200 or 300 feet deep. The abundance of Rhizopod
shells, as already stated, suggests that these were the main mate¬
rial ; and the recent observation that the lead in deep-sea sound¬
ings on the north Atlantic has brought up sand composed almost
wholly of minute Rhizopods, as published by Bailey, sustains
the conclusion. These shells are like grains of sand in size, and
are, therefore, ready for consolidation into a compact rock, need¬
ing no previous trituration by way of preparation ; and thus they
are especially fitted for making deep-water limestones. Corals
require the help of the waves to reduce them to grains before a
rock of compact texture can result. Moreover, the softness or
imperfect aggregation of Chalk is probably due to this origin, and
particularly to the fact that each grain is a cellular shell, or collec¬
tion of air-cells, instead of solid. The coral reefs of the Pacific do
not under ordinary circumstances give rise to chalk. The only
chalk known in coral regions is on Oahu, at the foot of an extinct
volcanic cone; and there it is probable that warm waters had some
connection with its origin.
The Flint, as stated on page 481, has been attributed to the sili¬
ceous Infusoria of the same waters and the spicula of Sponges. In
the soundings from the Sea of Kamtchatka, Bailey found micro¬
scopic siliceous shells of Infusoria (Diatoms) as abundant as the
Rhizopods in the Atlantic, which favors strongly this opinion.
The minute portion of silica which the alkaline waters of the ocean
can dissolve—especially when the silica is in what is called the
soluble state (p. 55), as is usual in these microscopic organisms—
gives an opportunity for that slow process of concretion which might
result in the flints of the Chalk. And the tendency to aggregation
around some foreign body as a nucleus, especially when such a
CRETACEOUS PERIOD.
489
body is undergoing chemical change or decomposition, explains
the frequent occurrence of fossils within flints, and the silicifiea-
tion of shells.
2. American Geography.—The Cretaceous beds of New Jersey
and of the rest of the border region of the continent, east and south,
show in their structure and position, and in the character of their
fossils, that they were formed either along a sea-coast or in off¬
shore shallow waters. Farther west, the limestones of Texas indi¬
cate a clearer sea; while the soft sandy and clayey formations to
the north are evidence that the same sea spread northward, but
mostly of diminished depth.
The outline of the formation over the land points out approxi¬
mately the outline of the sea in the Cretaceous period, and the
general form of the dry land. This is presented to view in the
accompanying map, in which the white part is the dry land of the
Fig. 792 A.
continent, and the shaded the Cretaceous area, and therefore the
submerged portion.
490
MESOZOIC TIME REPTILIAN AGE.
The line of the coast on the east extended from a point in New
Jersey, to the southeast of New York City, across to the Delaware
River, whose course it followed: this river, therefore, emptied into
the Atlantic at Trenton, and the regions of the Delaware and Che¬
sapeake Bays were out at sea. From the Delaware it continued
southwestward, at a distance of GO miles or more from the present
coast-line between New Jersey and South Carolina. It next turned
westward, being about 100 miles from the Atlantic in Georgia,
nearly 200 miles from the Gulf in Alabama, and still more remote
from the western Gulf shore in Texas. The Appalachians stood at
a less elevation than now, by GO to 100 feet.
The Gulf of Mexico, as the map illustrates, was prolonged north¬
ward along the valley of the Mississippi nearly to the mouth of the
Ohio, making here a deep bay. Into it the two great streams
entered, with only the mouth in common ; and probably the Ohio
was the larger, as its whole water-shed had nearly its present ele¬
vation and extent, while the Mississippi area was very limited.
More to the westward, from the region of Texas, the Gulf ex¬
panded to a far greater breadth and length, stretching over much
of the Rocky Mountain region, which was therefore so far sub¬
merged. It reached at least to the head-waters of the Yellow¬
stone and Missouri (which rivers were, therefore, not in existence);
and, judging from isolated observations in British America, the
waters may have continued northwestward to the Arctic seas, at
the mouth of Mackenzie River, where beds of this period occur.
This Cretaceous mediterranean sea spread westward among seve¬
ral of the elevations of the Rocky Mountain summits ; and in New
Mexico it spread still farther westward, over the region of the Colo¬
rado, to or beyond the meridian of 113° W.
By comparing the preceding map with that of the Azoic (p. 13G), it
is seen that the continent had made great progress since the open¬
ing of the Silurian age. But, as all this Cretaceous area was under
Cretaceous seas, much was still to be added to the permanent dry
land before its completion.
The great Interior Continental basin, which had been a lime¬
stone-making region for the most part from the earliest period
of the Silurian, was still, in its southern part,—that is, in Texas,—
continuing the same work ; for limestones 800 feet thick were there
formed. To the north of Texas, where the waters were shallower,
there appear to have been none of the Fchinoderms, Corals, Orbi-
tolinrc, etc. which were common in Texas.
It has been noted that during the Triassic and Jurassic periods
there were no marine beds formed on the Atlantic or Gulf borders
CRETACEOUS PERIOD.
491
above the present level of the ocean, except sparingly in estua¬
ries; and it lias hence been inferred that the continent on the
east and south, during that prolonged interval after the Appala¬
chian revolution, stood with the coast-line situated outside of its
present position (p. 441). And if it be true that the earlier half
of the Cretaceous rocks are not represented among the beds of
the Atlantic and Gulf borders, as now appears (p. 408), this
prolonged interval must have continued until this much of the
period had passed. The absence of sea-shore beds along a broad
and shallow ocean border, like that of the western Atlantic, cannot
otherwise be explained. The change submerging the present
coast did not conic on until the epoch of the Middle Cretaceous,
and perhaps not till part of it had passed (p. 408). The lowest
sandy beds, with their fossil wood, appear to mark the transition
from the elevated to the submerged condition of the border,
when the encroaching waters buried the vegetation of the land
and the Cretaceous formation of the present coast had its com¬
mencement.
It appears from the above that the preceding remarks on the
Geography of America in the Cretaceous period apply to the conti¬
nent only in the later part of the period.
3. Foreign Geography.-—The distribution of the Cretaceous
beds over other continents shows that the lands were to a great
extent submerged. The sea covered a large part of the region of
the Andes, as well as of the Rocky Mountains, and both chains
were to a great extent not yet flexed into mountain-shape; the
Alps, Pyrenees, and Himalayas were also under water, or only in
their incipient stages of elevation. Europe was mostly a great ar¬
chipelago, with its largest area of dry land to the north : it resembled
North America in the latter point, while widely differing in the
former. The Urals and Norwegian mountains were the principal
ranges of Europe, as the Appalachians and the Laurentian heights
of Canada and beyond were in America. Western Britain was the
high land of that region, and under its lee and that of other lands
southwestward across the Channel, the new formations of eastern
England and northern France were in progress on the borders of
the German Ocean.
4. Climate.—The geographical distribution of species indicates
a prevalence of warm seas in the northern hemisphere to the
parallel of GO0, and in the southern to the Straits of Magellan. For
the table on page 487 shows that several species are common to
Britain, Europe, and either equatorial America, India, or the
United States. The survey of the life of the period, therefore, as
492
MESOZOIC TIME REPTILIAN AGE.
far as now known, affords no evidence of the existence of the pre¬
sent cool temperature in the waters of the temperate zone.
The corals of the Cretaceous beds in England and Europe are so
closely related to the reef-forming species of the present seas, that
these concur with the other testimony in favor of warm seas.
Moreover, as such reefs reach now to about the parallel of 27°, the
coldest temperature of these regions, which is near 08° F., was
probably the coldest temperature of the waters of the German
Ocean, New Jersey shores, Mississippi basin, Vancouver's Island,
Chili, and Straits of Magellan. They were within what is called
the sub-torrid zone on the map of oceanic temperature.
The present position of the winter line of 35° F. on the Physio¬
graphic chart is probably near that occupied by the line of G8° F.
in the latter part of the Cretaceous period.
There is a difference in the later Cretaceous between the species
of northern and southern Europe, and also between those of the
northern and southern United States, as explained on page 479,
and this difference has been attributed to diversity of tempe¬
rature. Some diversity of this kind undoubtedly existed; and it
should be apparent in the fossils. But the particular facts re¬
ferred to may not be sufficient to prove it. In North America, at
least, the peculiarities in the life of the two regions, Texas and
the Upper Missouri, may be owing rather to the difference in the
horizpn of the beds, and also to that of clearness or purity of the
waters (Meek).
5. Life.—1. Retrospective characteristics (allying the Cretaceous with the
preceding period).
1. Among Plants.—A preponderance of Conifers ; numerous Cycads.
2. Among Radiates.—Crinoids of the Apiocrinns family and others.
3. Among Mollusks.—The genera Thee idea, Gryplixa, Exoyyra, Inoceramus,
Trigonia, Nerincca, Ammonites, Belemnites.
4. Among Vertebrates. — Pyenodont Ganoids, Cestraciont and Hybodont
Shark*, Dinosaurs, Eitaliosaitrs, Pterodactyls.
5. Species of plants and animals all extinct. Of the genera of plants only
one-twentieth living; of the genera of Cephalopods, only one-twentieth; of the
genera of fishes and reptiles, only one-sixth.
2. Characteristics peculiar to the Cretaceous.
1. Among Protozoans.—Great multiplication of genera and species of Rhi-
eopods and Sponges.
2. Among Radiates.—Echinoderms of the genera Ananchytes, Galerilcs;
Crinoids of the genus Marsupitcs.
3. Among Mollusks.—Species of Exoyyra and Inoceramus very common;
GENERAL OBSERVATIONS.
493
genera of the Ammonite family, Crioceras, Hamiles, Scaphites, Baculites, Turri-
lites, first appear; also Hippurites and other genera of Rudistes.
4. Among Vertebrates.—The Mosasaurus, and a few other Reptiles, besides
many genera of Fishes.
The prospective characteristics allying the Cretaceous with after-time are
mentioned beyond, in connection with the General Observations on the Meso¬
zoic.
GENERAL OBSERVATIONS ON THE MESOZOIC.
I. Time-ratios.
The estimate of the comparative lengths of the Palceozoic ages is
given on page 386. According to it, the lengths of the Silurian,
Devonian, and Carboniferous Ages are approximately as the ratio
3:1:1. The facts in European geology probably lead to the same
result; the doubt arises from the uncertain thickness of the Pri¬
mordial rocks.
The Mesozoic formations in America are too incomplete to be
used in such a calculation. In the Western Interior region the
whole thickness is only 5000 feet; and on the Atlantic border
nothing definite is yet ascertained. The Mesozoic rocks of Europe
and Britain afford more satisfactory data. The maximum thickness
of the Triassic (in Germany) is about 3400 feet, 1000 of it lime¬
stone; of the Jurassic, 5200 feet, 1000 of it limestone; of the Cre¬
taceous, 2400 feet, 1200 of it limestone : hence, for the whole Meso¬
zoic, about 7800 feet for sedimentary beds, and 3200 for limestone.
Making the calculation from these data, as on page 387, allowing 5
feet of sedimentary beds to correspond to 1 of limestone, the re¬
sulting number is 23,800; whence the time-ratio for the Palaeozoic
and Mesozoic is nearly 3.} : 1.
The time-ratio on the above data for the Triassic, Jurassic, and
Cretaceous is 7400 : 9200 : 7200, or approximately, for the three
periods, a ratio of 1 : 1] : 1.
Adopting D'Orbigny's conclusions with regard to the thickness
of the European Cretaceous (which are far from established), the
ratio between the Palaeozoic and Mesozoic is approximately 2:1.
II. Geography.
Through the Mesozoic, North America was in general dry land,
and on the east it stood a large part of the time above its present
level. Rocks were formed on its southeastern and southern border,
and over its great Western Interior or Rocky Mountain region.
Europe at the same time was an archipelago, varying in the extent
of its dry lands with the successive periods and epochs. Rocks
494
MESOZOIC TIME REPTILIAN AGE.
were in progress along its more southern borders and through its
interior seas.
In America there are but few distinct formations, the Triassio and
Jurassic making seemingly one continued series, and the Creta¬
ceous another with three or four subordinate divisions. In Europe
the number of epochal changes, or abrupt transitions in the rocks,
is large,—much more so than in the Carboniferous age.
In America there are no limestones, and therefore no evidences
of clear interior seas, except in the closing epoch of the Cretaceous
in Texas, and some thin interpolations in the earlier formations.
In Europe the Lias, and a large part of the Oolite and Chalk, are
limestone formations.
The facts indicate great simplicity and but narrow limits in the
oscillations of North America, and remarkable complexity and
diversity of extent in those of Europe.
III. Life.
1. Decline in Palxozoic Features.
Decline in Carboniferous genera of plants.—Of the genus Calamites
about 50 Carboniferous species have been described, only 3 or 4
Triassic, 2 .Jurassic, and none of later periods. The genera of ferns
Pecopteris, Neuropteris, Sphenoptcris, and Cyclopteris are continued in
the Mesozoic; but only one species in all—a Pecopteris—has been
found in the Cretaceous beds.
Pecopteris had 50 species in the Carboniferous age, 5 or 6 in the Triassic
period, the same in each the Jurassic and the Cretaceous; Neuropteris, 50 Car¬
boniferous, 8 Triassic, f> Jurassic, none Cretaceous; Sphenopteris, 75 Carboni¬
ferous, 20 Triassic and Jurassic, none Cretaceous; Cyclopteris, 34 Carboniferous,
4 Triassic, Jurassic none, Cretaceous none.
Decline in Crinoids.—There were over 500 species of Palaeozoic
Crinoids; of Jurassic, about 75; of Cretaceous, 15. Considering
the time-ratio for the Palaeozoic and Mesozoic, 31-: 1', these numbers
indicate an approximate equality between the eras. But it is still
true that the Mesozoic is much less prolific in individuals.
Decline in Brachiopods.— The number of known Palaeozoic spe¬
cies is about 700; of Triassic and Jurassic, 150; of Cretaceous,
about the same. These numbers do not exhibit the fact of the
decline. But it is strikingly seen in this: that the Brachiopods
were one-third the whole number of Mollusks in the Palaeozoic, and
only one-eleventh in the Mesozoic. Moreover, the Mesozoic species
belong extensively to the Terebrahda family, which is eminently a
LIFE.
495
modern type; 125 out of the 140 Cretaceous species were of this
family. Again, of the few Palaeozoic genera that hold over into the
Mesozoic, several die out before its close. This is true of Spirifcr,
Spirigera, Cyrtia, Lcptccna. The last species of the Spirifcr and Lep-
tccna families lived in the Lias, and the Mesozoic representatives
of these prolific genera are small compared with the earlier,—those
of Lcptxna hardly larger than an apple-seed (fig. GOO a).
Spirifer (and its allied genera) had 200 Palaeozoic species, 12 to 15 Triassic,
9 Jurassic; Leptxna, and the closely-allied Strophomena, 75 to 100 Palasozoic, and
only 5 of the former genus occur in the Liab, with which the type ends. Ilhyn-
chonellu is one of the few Brachiopod genera having living species : there were
about 120 Palaeozoic species, 50 Jurassic, 30 Cretaceous,—indicating no diminu¬
tion in relative number, considering the length of time for each era, though in
number of individuals under the species the diminution is marked.
The decline of the Brachiopod type is further observed in the
fact that the Tcrebralula family, which is the prevailing one in
the Mesozoic, is low in grade, as shown in its simple internal struc¬
ture and elongate form. The other Brachiopod groups cotempo-
raneous with it are nearly of the same inferior rank. Lingula,
which began in the Primordial, and still exists, is one of the lowest
types of the order.
Decline of the Cephalopod types of Ortlioceras, Goniatites, and Conularia.
—The simple Orthoceras, which began in the Potsdam period, had
its last representative in the Triassic. The genus Goniatites, of De¬
vonian origin, also ended in the Triassic. The genus Conularia,
dating from the Lower Silurian, became extinct in the Jurassic.
Disappearance of vertebrate-tailed Ganoids.—Of Ganoids with verte-
brated tails—the only kind in the Paheozoic—a few occur in the
Triassic, and these are the last fossil species of the kind.
Decline of the type of Ces-traciont Sharks.—This decline commenced
in the Palaeozoic and continues through the Mesozoic. It is now
nearly an extinct family.
2. Progress in Mesozoic Features.
Culmination of the type of Cycads.—The plants of the Mesozoic were
mainly Ferns, Confers, and Cycads. The ferns belong to a type—
that of Acrogens—which had passed its time of culmination in the
Palaeozoic. The Conifers were to have their fullest display in a
later era. The Cycads are eminently Mesozoic. They appear to
have begun near the close of the Carboniferous age, and passed
their climax in the Jurassic period.
In the Mesozoic era, 10 or 12 Triassic species of Cycads have been recog-
496
MESOZOIC TIME—REPTILIAN AGE.
nized, 70 Jurassic, and less than a dozen Cretaceous. Only a small part—pro¬
bably not a tenth—of the species that actually existed would have become fos¬
silized, as they are not confined to swampy soil.
Culmination of the Ceplialopod type, and therefore of the type of Mol¬
lusks.—The Cephalopods are the highest of Mollusks, and in their
culmination the culmination of the grand type of Mollusks took
place.
In the Triassic period, before the disappearance of the Gonia-
tites,—a Palaeozoic form of the Ammonite type,—true Ammonites
appeared, and the family rapidly multiplied in species and variety
of forms. Between 800 and 900 species have been found fossil in
the Mesozoie rocks. Besides these, the Bclcmnite family—charac¬
terized by an internal shell—commenced in the epoch of the Lias,
and over 120 of its species have been gathered from the Jurassic
and Cretaceous strata. There were also many species of Nautilus;
so that the whole number of Cephalopods now known from the
formations of the era is nearly 1200. Of this number about 950
were chambered shells of the Nautilus and Ammonite groups;
while in existing seas there are only four species, and these belong
to the single genus of Nautilus. The Ammonite and Belemnite
families have had no living representatives since the Cretaceous
period. It is to be noted that 950 is the number of species of
chambered shells found fossil: it may be only a third part (of
less) of those which were actually in the waters of the era. The
age was therefore remarkable for the great expansion of the type
of Cephalopods.
The number of species of the Ammonite family from the Triassic is about 100,
from the Jurassic 400 (over 100 from the Liassic), from the Cretaceous about
400. The genus Nautilus has over 40 Mesozoie species.
In the families of chambered shells the expansion of the Tetrabranch Cepha¬
lopods (p. 150) is exhibited; and in the Belemnite, Sepia, and Calamary fami¬
lies, that of the Dibranchs.
The Conulariee appear to have been the only representatives of the latter in
the Palmozoic. They are generally referred to the group of Pteropods; but
the large, thin, pyramidal shells, chambered at bottom, as Hall has observed,
and admitting of some motion at the angles above, correspond better with the
internal shell or osselet of a Cephalopod.
The type began in the straight Orthoceras with plain septa, and
the half-coiled and equally simple Lititite of the Lower Silurian;
it reached its maximum in the large and complex Ammonite, of the
Jurassic, and the associated Belemnite and Cuttle-fishes ; it declined
in the Cretaceous, through the multiplication of the half-coiled
forms of the Ammonite family (p. 485) and the straight Baculite.
LIFE.
497
The progress was from the simple and straight form through the
coiled and complex, to the straight again, though without a return
to the original simplicity in these straight shells. The Nautilus, which
was associated with the Orthoceras in the Silurian, had the same sim¬
plicity in its septa ; and this genus of chambered shells, out of the
forty or more that have existed, is the only one in our present seas.
The expansion of the type of Cephalopods was, therefore, not only
an increase in variety of forms and number of species, but also in
grade. With the Cretaceous period commenced the decline, and
at the close of the period there was a sudden falling off' in families,
genera, and number of species. Whether any of the modern
Cuttle-fishes (Dibranchs) are equal, or superior, to the highest
Cephalopods of the Jurassic, it is difficult to determine. The mo¬
dern genus Nautilus—representing the chambered species (Tetra-
branchs)—is certainly of far lower grade than the Jurassic Am¬
monite.
It is therefore one of the great facts connected with the Meso¬
zoic era that in its later half the sub-kingdom of Mollusks passed
its period of culmination. But, while this is true of the sub-king¬
dom as a whole, it is not true of each of its subdivisions ; for the
inferior tribes of Conchifers and Gasteropods continue on the
rising grade through the Mesozoic, and probably have their maxi¬
mum display in the age of Man. *
Culmination of the type of Ganoid Fishes.—The Ganoids, after the
Triassic, lose the Palaeozoic feature of vertebrated tails ; and this is
a mark of progress; for it is an example of that abbreviation of the
posterior extremity which generally marks elevation in grade as
well as progress in embryonic development.
In the Jurassic period, the number of species of Ganoids reached
its maximum, and also the diversity of generic forms. The Ganoids
are at present nearly an extinct tribe.
Over 300 Jurassic species have been described, besides nearly 50 Cretaceous,
and as many Triassic. The ordinary Ithoinbifers culminated in the Jurassic,
few of the genera continuing afterwards, while the Pycnodonts were numerous
in the Cretaceous,and continue to be largely represented in the Cenozoic.
Culmination of the type of Hybodont Sharks.—The Hvbodonts, which
began in the Palreozoic, are numerous in Mesozoic species, espe¬
cially in the Jurassic period, but almost extinct afterwards. Over
thirty Triassic and seventy-five Jurassic species have been de¬
scribed. It is at present an extinct tribe.
Culmination of the type of Labyrinthodon/s, and therefore of that of Am¬
phibians.—The scale-covered Amphibians, called Labyrintliodonts,
33
498
MESOZOIC TIME—RETTILIAN AGE.
which first appeared in the Carboniferous, have gigantic species in
the Triassic, and at its close cease. The type of Amphibians is
afterwards represented only by small species of the ordinary type
without scales.
Culmination, of the type of True Reptiles.—The Enaliosaurs or Swim¬
ming Saurians of the Triassic—the Nothosaur type—have the open
skull of a Batrachian. In the Jurassic the type rises to the higher
grade of the Ichthyosaurs and Plcsiosaurs, when there were several
genera and numerous species. In the Cretaceous the species are
very few; afterwards there were none.
The Lacertians commence in the later Palaeozoic, in species with
the ichthyic characteristic of biconcave vertebrae, and retain it
through the Triassic and in some Jurassic species. In the Jurassic
and Cretaceous they come forth in many other species of great size
without this low feature. After the Cretaceous only smaller species
exist.
The Saurian type in the later Jurassic rises also to the grade of
Dinosaurs, the highest in rank and among the largest of Reptiles;
and these all disappear before the close of the Cretaceous period.
There is also an expansion of the type to flying forms, the Ptero¬
saurs, in the Jurassic, and this type continues into the Cretaceous,
but then ends.
Thus, *in all the grand divisions there was a culmination and
decline. Every genus becomes extinct at the close of the era
except that of Crocodilus, which began in the Jurassic period.
The Reptilian type was unfolded in its complete dimensions, so
as to parallel the later expansion of Mammals. The sea, air, and
earth had each its species, and there were both grazing and carni¬
vorous kinds of large and small dimensions.
The reality of this Reptilian feature of the age will appear from a
comparison of England as it was in Reptilian times with England
as it is, or with India, Africa, and America.
In a single era, that of the Wealden and Lower Cretaceous,—for
the two were closely related in vertebrate species,-—there were in
the British dominions of sea and land four or five species of Dino¬
saurs twenty to fifty feet long, ten or twelve Crocodilians, Lacer¬
tians, and Enaliosaurs, ten to fifty or sixty feet long, besides Ptero¬
dactyls and Turtles. As only part of the species in existence would
have left their remains in the rocks, it would be evidently no exagge¬
ration to increase the above numbers two or three fold. But, taking
them as made out by actual discovery, the facts are sufficient to
establish the contrast in view. For, since man appeared, there is
no reason to believe that there has been a single large Reptile in
LIFE.
499
Britain; in India, or the Continent of Asia, there are but two species
over fifteen feet long; in Africa, but one; in all America, but
three ; and in the whole world, not more than six; and the length
of the largest does not exceed twenty-five feet. The number of
living species exceeding ten feet in length is only 16 or 18.
The Galapagos Islands are strikingly Reptilian at the present
time. But they afford only four lizards, as many snakes, a turtle,
and a large tortoise. The largest of the lizards, an aquatic species
of the genus Amblyrhjnchus (having feet, however, instead of pad¬
dles), is but three to four feet long.
If so large a number of species as above mentioned existed in
Britain and its vicinity during the age of Reptiles, what should be
the estimate for the whole world at that time? The question is a
good one for consideration, although no definite reply can be
looked for.
The culmination of the age of Reptiles occurred in the era of the
Wealden. But, as in the case of Mollusks, the culmination of the
grand type does not imply a culmination of all its subdivisions.
There is no evidence that the inferior group of Snakes had begun
to exist; and the Mesozoic species of Turtles are inferior in grade
to those of the Cenozoic and the present age.
3. Progress in Cenozoic Features.
1. Among Plants.—(a.) Angiosperms.—The introduction in the Cre¬
taceous of the great class of Angiosperms,—that to which all our
common fruit and shade trees belong.
(b.) Palms.—The introduction in the Cretaceous of the tribe of
Palms,—also eminent for its fruits and other useful products.
2. Among Radiates.—The introduction of the modern tribe of reef-
forming Corals, the Astrseoid Corals, and also the normal style of
Echinoids, that is, those having only the normal number of vertical
series of plates (p. 100), instead of an excessive number; as exem¬
plified in the Cidaris, and other groups of the age.
3. Among Mollusks.—An increase in the number of modern genera
of Conchifers and Gasteropods, and a larger proportion than before
of siphonated Gasteropods (beaked univalves) and siphonated
Conchifers.
Among modern genera the following begin in the Jurassic :—Rimula, Planor-
iis, Pal.udina, Jfelania, Nerita, Pterocera, Ilostellaria ?, Fusus, Tellina, Corbis,
Anomia, etc. In the Cretaceous:—Neithea, Crassatella, Axinsea (Pectunculus),
Petricola, Venus, Olioa, Ovula, Cyprsea, Voluta, Turris (Pleurotoma), Busy eon,
Pseudobuccinum, etc.
500
MESOZOIC TIME—REPTILIAN AGE.
The number of non-siphonated (or integripallial) Conchifers in the Meso¬
zoic, discovered up to 1849, according to a computation made by Bronn, was
2358, and of siphonated (or sinupallial), 1089; making the former over twice
as numerous as the latter. Broun gives for the corresponding numbers for
living species 1480 and 1190. Of the integripallial Mesozoic species, one-half
were Pleuroconchs (species having unequal valves), while in modern seas only
about one-fourth are Pleuroconchs, the Orthoconchs amounting to 73 per cent.
4. Among Articulates.—(a.) Crustaceans.—The rise of the class of
Crustaceans from Macrourans (Shrimps and Lobsters) to true Crabs.
These Crabs belong to the division of square Crabs (or the Grap-
soids) ; the higher divisions, the Cancer type (arched front) and
Maia type (triangular Crabs), are still unrepresented.
(6.) Insects.—The unfolding of the class of Insects, nearly all the
tribes being present in the later Jurassic,—even the highest tribe
of Hymenopters, in the form of a species related to the Bee.
5. Among Vertebrates.—(a.) Teliost Fishes.—The introduction in the
Cretaceous of the grand tribe of Teliosts, or common osseous fishes;
and among the early representatives of the tribe there were species
related to the Salmon, Herring, and Perch.
(b.) Selachians.—The introduction in the Jurassic of the modern
tribe of Sharks,—the Squalodonts (genera Sphenodus, Lamna, Oxy-
rhina, Notidanus, etc.).
(c.) Crocodiles.—The appearance in the Jurassic of the first species
of the modern genus Crocodilus.
(d.) The introduction of the class of Birds, in the Jurassic period,
if not, earlier, in the Triassic.
(e.) Earliest Mammals,—Marsupials and Insectivores.—The introduc¬
tion in the Triassic of the earliest of Mammals, and their increase in
genera in the Jurassic,—the species, Marsupials and Insectivores.
4. System in the Progress of Life.
Comprehensive Types.—Next to the Labyrinthodonts, remarked
upon on p. 395, the Cycads are the most marked example of a com¬
prehensive type in the Mesozoic. These plants—the characteristic
species of the era—are related in some fundamental points both to
the Ferns and Palms. They are like the former in that the leaves
are rolled into a coil in the bud, and unroll on expanding; they
resemble the latter in the form of their foliage and in the general
habit of the plant. The first was a retrospective feature, for the
Ferns were of Palaeozoic origin; the latter was prospective, the
Palms not having yet appeared.
The Marsupials are another example under this head. They
LIFE.
501
approach Beptiles and Birds in their semi-oviparous character; they
are like the former also in the sacrum consisting of but two verte¬
bra combined; and among the lower species of later time the
birds are represented by the Duck-bill (Ornithorhynchus) and Bep-
tiles by the Echidnus. Along with these inferior features there were
the dominant characteristics of the true Mammal.
A subordinate example of the comprehensive type is seen in the
Rhynchosaur of the Trias, which combined the characteristics of
the Saurian with the bill, and partly the skull, of a Turtle. Whe¬
ther it had paddles or not is undecided.
All the examples here mentioned, it will be observed, made
their appearance in the Trias.
The Reptilian Birds of the Jurassic represent another of the comprehensive
types. There appear also to have been Reptiles, having some Crnithic characters,
at least in the form of the feet. (See p. 425.)
Earliest Mammals.—On p. 390 several examples are mentioned in
which the early species of a group were partly from the lower of its
two grand subdivisions, and partly from the inferior grades of the
higher. If, in a similar manner, Mammals are divided into Marsu¬
pials (the lower division) and Non-marsupials (the higher), the ear¬
liest kinds embrace species of the former, along with Insectivores,
a tribe in the inferior or Microsthenic division (p. 423) of the
latter.
The species of the higher group are not necessarily from its lowest sub¬
division. Below the Insectivores there is the Sloth tribe, or that of
Edentates; and this low group is not known to occur before the
Cenozoic (Tertiary). In the same manner the Beptilian associates
of the early Amphibians were Lacertians and Enaliosaurs, and not
Snakes of the inferior subdivision of True Beptiles. The earliest-
known Snakes are found in the Tertiary.
In the limited Fauna and Flora of early time the species of the
higher group arc such as blend harmoniously with those of the lower. This
principle is illustrated on p. 390. In the case of Mammals, the
Marsupial Insectivores harmonize better with the Non-marsupial
Insectivores than they would with Sloths, and the Labyrintho-
donts better with Lacertians than with Snakes. Again, the air-
breathing Vertebrates of the Mesozoic, made up of oviparous Bep¬
tiles, semi-oviparous Mammals, and viviparous Mammals, are an
harmonious assemblage. The fauna of an era is not well appre¬
ciated unless considered apart from those of other periods. An
attempt to classify the living species as they would have appeared
502
MESOZOIC TIME—REPTILIAN AGE.
to a mind in the age itself, having in view co-existing species and
those that had gone before, is an essential preliminary to a correct
apprehension of the life of each epoch.
5. Disturbances daring, and at the close of, the Mesozoic Era.
In American history we have found evidences of disturbance in
the tilted beds of the Connecticut River sandstone and the inter¬
secting trap, as mentioned on p. 430. The period of the uplift is
not ascertained; but it is evident that it preceded the Cretaceous
period, as the Cretaceous rocks are undisturbed and without trap
dikes. The destruction of species was complete, as none pass up
into the Cretaceous.
The Cretaceous strata are all concordant in stratification. They
indicate oscillations of level in the land and sea, but no violence
at any interval during their deposition.
In Europe, as in America, the Palaeozoic closed amid scenes of
great disturbance and metamorphism. But during the progress of
the Reptilian age the rocks, Triassic, Jurassic, and Cretaceous,
appear to have been laid down for the most part conformably, with
few examples of non-concordance, yet with those variations in their
distribution that arise from variations of the ocean's level, as a con¬
sequence of gentle lieavings of the earth's crust. There were thus
elevations and depressions, producing the varying geography of the
age, and successive destructions of species attending them, so that
but an extremely small number of Liassic species pass up into the
Oolite,—D'Orbigny says none,—and less than a dozen from the Ju¬
rassic to the Cretaceous; while the many subordinate epochs also
were separated by general destructions, and peopled mostly by in¬
dependent creations.
A disturbance took place between the Triassic and Jurassic periods in the
region of the Tliuringian Forest and the frontiers of Bohemia and Bavaria, the
Jurassic beds overlying unconformably the Triassic : it is named by De Beau¬
mont the System of the Tliuringian Forest, and the direction mentioned is N. 50°
W. Again, between the Jurassic and Cretaceous was formed De Beaumont's
System of the Cote d' Or, having the direction N. 50° E.
The rocks of the Cfetaceous and Jurassic are still very nearly
horizontal in the great Anglo-Parisian region (the part of the
German Ocean basin exposed to view).
The close of the Mesozoic era (or that of the Cretaceous period)
was a time of disturbance unequalled since the close of the Pakeo-
zoic. Its effects are apparent,—
1. In the destruction of life.—No species, either in Europe or
DISTURBANCES CLOSING THE REPTILIAN AGE. 503
America, is yet ascertained to have lived through the interval into
the Mammalian age. Moreover, very many of the genera and some
large families of species abounding in the Chalk are afterwards un¬
known, as has been already illustrated.
2. In the distribution of the Cretaceous beds, as contrasted with those
of the succeeding age.—The Cretaceous seas covered the summits
of parts of the Rocky Mountains and Andes. These lofty ranges
have since been raised, and in part the elevation took place
before the epoch of the Tertiary, whose marine beds lie at their
base. Vast additions were thus made to the continents. From
similar evidence it is known that the Pyrenees and Carpathians
were raised into existence in the early Tertiary ; and, while the
Alps were in part of much later date, dislocations and elevations
in the French Alps (Mount Viso system of De Beaumont) and the
southwestern extremity of the Jura are traced to the middle or
close of the Cretaceous. The surface of the Chalk of England is
described as bearing marks of very extensive denudation, proving
its elevation above the ocean in which it was formed before the
Tertiary beds were deposited.
The evidence thus far collected is sufficient to sustain the state¬
ment that the epoch following the close of the Mesozoic era, like
that after the Palaeozoic, was one of revolution, and that the dis¬
turbances ended in extensive additions to the dry land of the
globe.
But there is no reason to believe that the revolution was the
result of an instantaneous movement. It was probably slow in
progress, like others that had preceded it, and may have occupied
a long age. Moreover, this era of disturbance was continued
through the Tertiary period, during which the Pyrenees, Alps, Apen¬
nines, Himalayas, and other mountains reached nearly to their
present altitude above the level of the ocean, and the continents
attained in general their full extent.
The relative positions of the Cretaceous beds and marine Ter¬
tiary in North America (see map, p. 133) afford data for estimating
the change of level after the Mesozoic era on the North American
Continent. In this way we learn that on the Atlantic border the
change was slight, and in general there was no upward movement;
for the Tertiary formation mostly covers the Cretaceous. On the
Gulf border in Alabama the rise could not have exceeded 100 feet;
along the Mississippi, towards the mouth of the Ohio, it may have
been 275 feet; and about the head-waters of the Mississippi, the
great central plateau of the continent, 1700 feet.
West of the Mississippi, as already stated, the changes were
504
MESOZOIC TIME—REPTILIAN AGE.
great, raising out of the sea a large part of the Rocky Mountain
region. About Santa Fe in New Mexico, the Cretaceous beds are
0000 and 7000 feet above the sea ; near Pike's Peak, 4500 feet; at
Deer Camp on the North Platte, nearly 0000 feet; on the Big Horn
Mountains, 0000 to 7000 feet; about Fort Benton on the Upper
Missouri, and westward along the base of the mountains, 4000 to
G000 feet; in the vicinity of the Wind River Chain, G800 feet.
Hence, the whole rise since the close of the Cretaceous about the
central region of the Rocky Mountains has amounted to nearly
7000 feet; and from this it decreased eastward towards the Missis¬
sippi and westward towards the Pacific. What part of this eleva¬
tion in these mountain-regions took place immediately after the
Mesozoic era, and how much later, is not easily ascertained. Part
was unquestionably of later date, as Ilayden has shown. This sub¬
ject comes up again under the general observations on the Cenozoic.
The elevation of the great plateau appears to have been a gra¬
dual upward movement without much disturbance of the rocks.
Through 3000 or 4000 feet, nearly to the base of the summit-moun¬
tains, as Ilayden observes, the beds are nearly or quite horizontal.
But along the sides of the mountains there is some dip, though
usually small. On both the east and west sides of the Wind River
Chain, and about the Big Horn Mountains, the dip does not exceed
one or two degrees. West of the Black Hills, however, and in
some other localities, the beds incline 10° to 25°.
Causes of the Destruction of Life.—The complete extermination of
species at the close of the Cretaceous period has not been fully ex¬
plained. It was probably connected with the great changes of
level which took place at the time, as has been shown, over the
Eastern and Western continents. The elevations to the north may
have been even greater than has been supposed; for elevations
do not leave as indubitable a record as subsidences. In North
America there are no Tertiary beds known north of southern New
England on the east, and none in the Arctic,—-indicating, appa¬
rently, that the whole area was above the sea then, as now. The
emergence of the continents would have extinguished the life of
the continental seas ; and a large increase of land in the higher
temperate and polar regions would have given completeness to the
destruction by causing a colder temperature in both the air and
the waters. It is therefore most probable that the destruction was
due (1) to the more or less complete emergence of the continents
and accompanying elevation of mountain-ranges; and (2) to a
change of climate and oceanic temperature,—both the air and
oceans being rendered colder than in the Mesozoic era.
CENOZOIC TIME.
505
IV. CENOZOIC TIME.
Tt has been observed that before the close of the Mesozoic the
medieval features of the era were already passing away. The
Cycads had begun to give place to Oaks, Willows, and Palms ; the
ancient type of Ganoids, to Salmon, Perch, and Herring ; and the
corals, Echini, and shells were in a great degree allied to those of
existing seas, though all of extinct species. But, notwithstanding
these progressing changes, the Mesozoic aspect continued on to the
end, appearing prominently in the multitudes of Ammonites and
Belemnites, in the predominance of Cestracionts and Ganoids
among fishes, and in the supremacy of the great class of Reptiles.
Even the little Mammals which appeared among the Reptiles bore
the mark of the age; for the larger part, at least, approximated to
'the oviparous Reptiles and Birds in being themselves of a semi-
oviparous type, the Marsupial.
But these Mammals were prophetic species; and with the
opening of a new era the Reptiles dwindled in numbers, variety,
and size, and Mammals in their turn became the dominant race.
At the same time, types much like those of the age of Man were
multiplied in all departments of nature. As the era advanced, the
first of living species appeared,—a few among multitudes that be¬
came extinct, and afterwards a larger proportion; and before its
close, nearly all kinds of life, excepting Mammals, were identical
with those of the present era. As the Palaeozoic or ancient life was
followed by the Mesozoic or Medieval, so now there was as marked
a change to the Cenozoic or recent life and world.
Cenozoic time embraces only a single age, the age of Mammals.
MAMMALIAN AGE.
The age of Mammals is divided into two periods:—
1. The Tertiary, in which all the Mammalian species are extinct,
and the proportion of living Invertebrates—Radiates, Mollusks,
Articulates—varies from none in the early part of the period to
90 per cent, in the latter part.
2. The Post-Tertiary, in which nearly all the Mammalian species
are extinct, but the Invertebrates are nearly all living, not over 5
per cent, being extinct.
The name Tertiary is a relic of early geological science. When
506
CENOZOIC TIME—MAMMALIAN AGE.
introduced, it was preceded in the system of history by Primary
and Secondary. The first of these terms was thrown out when the
crystalline rocks so called were proved to belong to no particular
age,—though not without an ineffectual attempt to substitute it
for Palaeozoic; and the second, after use for a while under a re¬
stricted signification, has given way to Mesozoic. Tertiary holds
its place simply because of the convenience of continuing an ac¬
cepted name.
I. TERTIARY PERIOD (19).
Epochs.—The Tertiary has not been satisfactorily divided into
epochs either in America or Europe. This arises from the fact that
in this later part of the Earth's history the changes in progress
were of a less comprehensive or more .local character than in
earlier time. Consequently, the subdivisions often vary widely on
different parts even of the same continent.
Lyell has divided the beds into three series, according to the
proportions of living species :—
1. Eocene (from 7/«f, dawn, and icaivog, recent, the same word from
which Cenozoic is derived): species all extinct. (When the term
was introduced, 5 or 10 per cent, were supposed to be recent.)
2. Miocene (from peiuv, less, etc.): 10 to 40 per cent, living
species.
3. Pliocene (from nTieiuv, more, etc.): 50 to 90 per cent, living.
But these proportions are not capable of general application. It
is possible that beds in America containing all extinct species may
be synchronous with those of Europe, in which there are ten or
fifteen species of recent shells. Moreover, not even the subdivisions
in different parts of Europe can be made to correspond to these
epochs: still, they are convenient terms for Lower, Middle, and Upper
Tertiary, and with proper caution may be used to the advantage of
the science.
1. AMERICAN TERTIARY.
Ei'ocns:—1. Claiborne, or that of the Tertiary beds of Claiborne,
Alabama; 2. Jackson, or that of the beds of Jackson, Mississippi;
3. Vicksburg, or that of the beds of Vicksburg, Miss. The species
of animals of these three epochs are all extinct, and the beds have
been referred to the Eocene. 4. Yorktown, or that of the beds of
Yorktown, Virginia, in which fifteen to thirty per cent, of the spe¬
cies are living,—usually called Miocene. 5. Sumter, or that of the
beds of Sumter and Darlington districts of South Carolina, in which
TERTIARY PERIOD-
507
forty to sixty per cent, of the fossils are living species,—called
also Pliocene.
I. Rocks : kinds and distribution.
The Tertiary areas on the map, p. 133, are lined obliquely from
the left above to the right below ; and the fresh- and brackish-
water Tertiary which occurs on the slopes of the Rocky Mountains
is distinguished from the marine by a more open lining.
The general distribution of the beds is similar to that of the Cre¬
taceous. On the Atlantic border the most northerly point is Martha's
Vineyard. In New Jersey, and to the south, through Maryland,
Virginia, and the Carolinas, they cover a narrow coast-region ; and
from South Carolina they spread westward along the Gulf border,
the inner limit of the region being about 100 miles from the Gulf
in Alabama, and 150 to 200 in Texas. Along the Mississippi River
the Gulf border region extends northward to southern Illinois.
Unlike the Cretaceous formation, the marine tertiary strata do
not cover the Missouri region. Isolated brackish-water deposits
(determined to be such by the fossils) are found over parts of it,
and a great fresh-water Tertiary, sometimes called a Lignitic forma¬
tion, spreads widely over the western plateaus or slopes of the
Rocky Mountains both north and south of the Upper Missouri (dis¬
tantly-lined areas on the map, p. 133).
Marine Tertiary beds occur also on the Pacific coast, in California
and Oregon.
The Tertiary strata, as implied above, are either of fresh-water,
brackish-water, or marine origin, and they often vary greatly in
character from mile to mile. Instead of great strata of almost
continental extent and uniformity, as in the Silurian, there is the
diversity which is found among the modern formations of the
coast.
These modern formations, now in progress, should be studied
in order to an understanding of the Tertiary. In one spot there
are mud-beds, with oysters or other mollusks ; in another
region, great estuary flats ; a little higher, on the same coast
perhaps, accumulations of beacli-sands with worn shells, changing
in character every few rods. In another region, coral lime¬
stones are in progress, as off the Florida coast; and on other
shores, coarse shell limestones. Still further to conqnelkeiid
the diversity in the deposits, it is necessary to remember that by
the throwing up or removal of embankments on coasts, or by
change of level, salt-water marshes or estuaries may become brack-
isli-water, or wholly fresh-water, and the reverse, — each change
508
CENOZOIC TIME MAMMALIAN AGE.
being attended with a change in the living species of the waters,
encroaching fresh waters destroying the marine species, and so on.
By considering carefully all the various conditions incident to a
coast from these sources, the ever-varying character of the Tertiary
beds will be appreciated.
The rocks are of the following kinds :—beds of sand or clay, so soft
as to be easily turned up by a shovel ; compact sandstones, useful for
a building-stone, though not very hard; shell-beds of loose shells
and earth, the shells sometimes unbroken, in other cases water-
worn ; shell-rocks and calcareous sandstones, consisting of pulverized
shells and corals firmly cemented and good for building-stone, as
at St. Augustine ; marls, or clays containing carbonate of lime from
pulverized shells, and hence effervescing with the strong acids;
compact solid limestones, sometimes oolitic in structure; buhrstone, a
cellular siliceous rock, valuable for millstones, as in South Caro¬
lina. The clays and sand-beds often contain lignite (or brown coal
derived from vegetation), and are then called Lignite beds.
Although the Tertiary rocks are generally less firm than those
of the Palaeozoic, there are in some places hard slates and sand¬
stones not distinguishable from the most ancient. Such rocks
occur in California, in the vicinity of San Francisco; and it has
been suspected that some crystalline rocks of the region are altered
Tertiary strata.
There are also beds of whitish earthy or chalky aspect, which
consist of siliceous Infusoria, and others, of the shells of Rhizo-
pods.
Claiborne, Jackson, and Vicksburg Epochs.—Eocene.—The Tertiary beds which
contain only extinct species of fossils, and are therefore called Eocene, occur in
Maryland, Virginia, North and South Carolina, and the States bordering on
the Gulf of Mexico. The beds of the several epochs are best displayed and
most distinct in Mississippi and Alabama.
The beds of the Claiborne epoch, or Lower Eocene, well developed about
Claiborne, Alabama, consist, beginning below, of (1) Clay, 25 feet, overlaid by
a bed of lignite, 4 feet; (2) Marl with oysters (0. sellseformis); (3) Marly are¬
naceous limestone; (4) Marl with oysters; (5) Sand with shells partly showing
a beach-origin, often called the " Orange-sand" group in the region. Whole
thickness, about 125 feet.
In Mississippi, according to Hilgard, there are (1) the Northern Lignitic
group, consisting in some places, at base, of small estuary deposits with marine
shells, and above of clays and sands with Lignite and fossil leaves,—covering a
large part of the northern half of the State; and the Lignitic group of N. Lau¬
derdale,—the latter overlaid by (2) Siliceous Claiborne beds, sandstones and
claystones, in Lauderdale, Newton, etc., near middle of western half of the
State; (3) Lignitic clays of N. Clarke co.: (4) Calcareous beds, white and
TERTIARY PERIOD.
509
bluish marls, the former often indurated, with numerous shells, in Clarke co.,
south of the preceding. Whole thickness, 425 feet.
In Tennessee, there are, below, beds of sand (orange-sand at surface, from
alteration of the oxyd of iron) with some clay,—the Porter's Creek group, 200-
300 feet thick; and over these layers, sand-beds containing Lignite, the La¬
grange group, 300-400 feet thick, covering a large area in western Tennessee.
(Safford.)
Near Charleston, S.C., (1) Buhrstone beds, 400 feet; (2) White limestone and
marls, called the Santce beds. A Buhrstone of the same age occurs also in
Georgia and Alabama. The epoch is represented also near Fort Washington,
Piscataway, and Fort Marlborough, in Maryland, and on the Pamunkey at
Marlbourne, mostly by dark-green sands.
In the Upper Missouri region there is a great Lignite group, 2000 feet or
more thick, which contains much Lignite, numerous leaves of plants, and occa¬
sionally in its lowest part shells of brackish-water Mollusks, as Ogsters, Corbi-
culre, etc., mingled with fresh-water species, Viviparse, Melanise, etc. (figs. SOS-
SOS). It occurs about Fort Union, extends far north into British America, and
south to Fort Clarke; also on the North Platte, above Fort Laramie, on the
west side of Wind Biver Mountains, and into Green River Valley. (Meek &
Hayden.)
A Lignite formation of Eocene age occurs also in Texas. (Shumard.)
In California, the Claiborne epoch is represented at the Canada de las Uvas,
near the south extremity of the Tulare valley, where the Carclita planicosta, or
a species near it, occurs.
The beds of the Jackson epoch, or Middle Eocene, as observed at Jackson,
Miss., are (1) Lignitic clay; (2) White and blue marls, the former often indu¬
rated, with numerous marine shells and remains of the Zeuglodon. They cross
the State as a narrow band running E.S.E. through Scott and Jackson cos.
Whole thickness, 80 feet. (Hilgard.)
The beds of the Vicksbnrg epoch, or Upper Eocene, as represented at Vicks-
burg, Miss., are (1) Lignitic clay, 20 feet; (2) Ferruginous rock of lted Bluff,
with numerous marine fossils, 12 feet; (3) Compact limestones and blue marls,
with marine fossils, often called the Orbitoides limestone, 80 feet: in all, 112
feet. A narrow band crosses the State just south of the Jackson beds, from
Vicksburg on the Mississippi. These are overlaid by 150 feet of the "Southern
Lignitic" or " Grand Gulf" group of clay, sandstone, and loose sand, with some
gypsum, occurring about Grand Gulf, on the Mississippi, and covering the
larger part of the southern portion of the State. (Ililgard.)
The Vicksburg group is met with in Alabama, in Monroe, Clarke, and Wash¬
ington cos., and constitutes a limestone bluff at St. Stephens on the Tombeckbee ;
limestone at Tampa Bay, Florida; gray marl on the Ashley and Cooper Rivers,
South Carolina, abounding in Rhizopods, and, along with the Santee beds,
having a thickness of 600 to 700 feet.
In the Upper Missouri region, there are fresh-water beds 1000 feet thick, con¬
sisting of white and drab clays with some layers of sandstone and local beds
of limestone, which are either of the Vicksburg or Yorktown epoch. They
occur in the Bad Lands (Mauvaises Terres) of White River (whence they have
been called the White Iliver group by Meek & Hayden), on the Niobrara, and
510
CENOZOIC TIME—MAMMALIAN AGE.
across the country to the Platte River. They are the burial-place of the Titano-
therium and other extinct Tertiary Mammals, and contain also a few fresh-water
shells of extinct species.
The beds are referred to the Miocene by Leidy.
There are also in the Wind River valley, and on the west side of the
Wind River Mountains, other fresh-water deposits, 1500 to 2000 feet thick,
called the Wind River group, which may be of the same age as the above, or
possibly intermediate between them and the Lignitic group. (Meek &
Ilayden.)
The age of some of the Lignite beds is not yet wholly beyond doubt. This
is the case, as Hilgard observes, with the Northern of Mississippi, as they have
not been seen underlying the marine beds with shells. Yet their position in the
State between the Cretaceous in the northeast corner and the acknowledged
Claiborne across its centre, favors the idea of their being intermediate in age,
and sustains Hilgard's arrangement of them. The Lauderdale beds are un¬
questionably under the Claiborne. Moreover, beds with similar fossil leaves
occur in Arkansas at the base of the Tertiary of that State, as shown by the
sections, and also in Texas.
The Eocene age of the Great Lignite formation of the Upper Missouri, 2000
feet thick, is doubted by some. But, as Meek & Ilayden observe, (1) it underlies
the Titanotherium Tertiary, and is therefore older, and, being of so great thick¬
ness, it must extend down into the Eocene; (2) the brackish-water beds in its
lower part, containing Oysters, Mclanim, etc., show that the deposits were formed
when the Cretaceous seas were disappearing, and changing to the fresh-water
areas of the later epochs; (3) the remains of a species of Lepidotus, an Eocene
genus, occur in the beds.
There is a Lignite deposit at Brandon, Vermont, associated with a bed of
Limonite iron-ore and abounding in fossil fruits, first described by E. Hitch¬
cock. The plants, according to Lesquercux, are of the same period with those
of the Mississippi, Tennessee, and Arkansas Lower Lignite beds.
The principal source of doubt in all these cases comes from the fact that the
fossil plants, as both Lesquercux and Newberry say, are most analogous to
those of the European Miocene. The geological evidence that they are Eocene
appears, however, to be too strong to be thus set aside; and, if admitted, the
difference between Europe and America as to vegetation is quite parallel with
what is observed in the Cretaceous; for the American Cretaceous plants and
the beds containing them have been pronounced by European paleontologists
to be Tertiary, notwithstanding the stratigraphical impossibility.
Yorktown Epoch.—Jlfiocene.—The YArktown beds cover a large part of the
Atlantic Tertiary border, occurring at Gay Head on Martha's Vineyard; in New
Jersey, in Cumberland co. and elsewhere, and fossils may bo collected in the
Marl pits of Shiloh, Jericho, etc.; in Maryland, at St. Mary's, Easton, etc.,
occurring on both sides of the Chesapeake for a great distance; in Virginia, at
Yorktown, Suffolk, Smithfield, and through the larger part of the Tertiary
region.
In California and Oregon the beds referred to the Miocene consist of sand¬
stone and shale, and are in some places 1500 feet thick. They occur near Asto¬
ria, on the Columbia River and Willamette; at San Pablo Bay, near San Fran-
TERTIARY PERIOD.
511
eisco; in many parts of the San Joaquin and Tulare valleys, in the Estrella
valley, Santa Inez Mountains, San Raphael Ilills; at Oeoya Creek,* along the
flanks of the Peninsula range in the latitude of San Diego, etc. Both north
and south of San Francisco, on the coast, there arc metamorphic slates, partly
taleose, which are either Tertiary or Cretaceous : and the talcose slaty rock
containing tho Quicksilver mines, between San Francisco and Monterey (at
New Almaden and in that vicinity), is supposed to he part of the scries.
The strata at Gay Head, beginning below, are (1) Clay, filled with Turritella
alticostata, Callista (Cytherea) Sayana, etc.; (2) Sand, with few shells, chiefly
Yoldia (Nucula) limatula; (3) a sandy bed made up mostly of Crcpidula costata ;
(4) coarse ferruginous sand. Two miles off, the layer of Turritellm has changed
to a layer of Crcpidula?, and the continuation of the Crepidula layer is filled
with Pectens, Venus difformis, Ostrea, etc.
At a locality on James River, Va., there are (1) a layer of shells of Peclen
and Ostrea, 5 feet; (2) bed of Chamse, 3 feet; (3) bed of Pectens with Ostrese, 1
foot; (4) second bed of Chamse, with Area centenaria, Panoptea reflexa, G feet;
(5) bed of large Pectens, 2 feet; (6) closely compacted bed of Chamse and Venus
difformis, 3 feet; (7) sand and clay separated from the preceding by a thin
layer of pebbles. But in other localities of the same region the beds are dif¬
ferent. The first layer over the Eocene often consists of pebbles or coarse
sand.
One of the most remarkable deposits in the Virginia Tertiary is a bed of In¬
fusorial remains occurring near Richmond. It is in some places thirty feet
thick, and extends from Herring Bay on the Chesapeake, Md., to Petersburg,
Va., or beyond, and is an accumulation of the siliceous remains of microscopic
organisms, mostly Diatoms. Some of the beautiful forms are represented, much
magnified, in fig. 792 B. These beds have been referred both to the Miocene
and Eocene: they are called Eocene by Professor Rogers after an examination
of the region.
A still thicker bed—exceeding fifty feet—exists on the Pacific at Monterey ;
the bed is white and porous like chalk, and abounds in siliceous organisms.
(Blake.)
Sumter Epoch.—Pliocene.—The beds of the Sumter epoch occur in North and
South Carolina, extending south as far as the Edisto River. They contain forty
to sixty per cent, of living species of shells. (Tuomey & Holmes.) The beds are
soft, either loam, clay, or sand, and lie in depressions of the older Tertiary and
the Cretaceous formations. Unless these beds are the equivalents of the Vir¬
ginia Miocene, they are not represented, as far as now known, in Virginia or
farther north. No beds of this epoch have been reported from the Gulf States.
In the Upper Missouri region the White River group is overlaid by other fresh¬
water Tertiary beds, 300 to 400 feet thick, called by Meek & Hayden the Loup
River group. They contain in their upper part the remains of numerous ex¬
tinct Mammals, including Camels, Rhinoceroses, Elephants, etc., besides land
and fresh-water shells which are probably of recent species. These beds occur
on the Loup Fork of the Platte, and stretch north to the Niobrara and south
beyond the Platte. The fossils are supposed to be of Pliocene age.
512
CENOZOIC TIME—MAMMALIAN AGE.
H. Life.
I. Plants.
1. Protophytes.—About one hundred species of Diatoms have been
described by Ehrenberg and Bailey from the Infusorial stratum
Fig. 792 B.
Richmond Infusorial Earth.—a, Pinnularia peregrina; 5, c, Odontidiuni pinnulatum; a,
Grammatopliora marina; e, Spongiolithis appendiculata; f Melosira sulcata; g, transversa
view, id.; h, Actinocyclus Ehrenbergii; i', Coscinodiscus apiculatus; j, Triceratium obtu-
sum; le, Actinoptyclius nndulatus; I, Dictyocha Crux; m, Dictyoclia; n, fragment of a
segment of Actinoptyclius senarius; o, Navicula; p, fragment of Coscinodiscus Gigas.
of Richmond, besides a few Polycystines (siliceous Protozoans) and
many sponge-spicules. Fig. 792 B represents a portion of the
earth as it appeared in the field of view of Ehrenberg's microscope.
2. Angiosperms, Conifers, Palms.—Leaves of plants have been gath¬
ered from the Lignite beds of Mississippi, the older Eocene of Hii-
gard ; from the similar beds of Arkansas, and those of the Upper
TERTIARY PERIOD.
513
Missouri, also older Eocene; from a bed of Lignite at Brandon,
Vt.: and from Bellingham Bay, Vancouver's Island, on the Pa¬
cific. Among the plants are species of Plane-tree, Oak, Poplar, Maple,
Hickory, Dog-wood, Magnolia, Cinnamon, Fig, Conifers, Palms, etc.
Palm-leaves have been found as far north as the Upper Missouri
region. Specimens collected by Hayden are of the fan-palm
family,—a species of Sabal,—and one leaf when entire must have
had a spread of twelve feet.
The plants of the beds of Mississippi, the Upper Missouri, and
other localities mentioned, are closely related, according to both
Figs. 793-797.
Fig. 793, Quercus myrtifolia ?; 794, Cinnamomum Mississippiense; 795, Calamopsis Danse ;
796, Fagus ferrugiuea?; 797, Carpolithes irregularis.
Lesquereux and Newberry, to those of the Miocene of Europe, and
;ire also much like those of the present era. It follows, then, if
the order of the beds is correctly determined,—as can hardly be
doubted,—that the forests of the American Eocene resembled
those of the European Miocene, and even of modern America.
Among the genera of the older Lignite beds distinguished by Lesquereux and
Kewbcrry are (1) Aiigiosperms,— Quercus, Carya, Popiilns, Acer, Moms, Carpinus,
34
514
CENOZOIC TIME—MAMMALIAN AGE.
Negundo, Snpindus, Ficus, Laurus, Persea, Salisburia, Cornus, Rhus, Olea,
Rhamnua, Terminalia, Magnolia, Smilax, Cinnamomum; (2) Conifers,— Thuja,
Sequoia, Taxodium, Glyptostrobus ; (3) Palms,—Sab a I, Calamopsis.
Fig. 793, Quercus myrtifolia (?), from Sommerville, Tennessee, the Lagrange
group of S.ifford; fig. 794, Cinnamomum Missistsip-
piense Lsqx., from Mississippi, northern Lignitic
group,at Winston; fig. 795, Calamopsis Pause Lsqx.,
from Mississippi, northern Lignitic group, in Tip¬
pah, Lafayette, Calhoun ; fig. 796, nut of Fagus
ferruginea ? from the Lagrange group of Tennes¬
see : fig. 797, Carpolithes irregularis Lsqx., from the
Brandon Lignite bed; fig. 797 A, Carpolithes Iiran-
donensis Lsqx., the most abundant of the Brandon
nuts, natural size. The kind of plant producing
these two fruits is undetermined. Among the
other Brandon fruits Lesquereux has recognized
the genera Carya, Fagus, Aristolochia, Sapiudus,
Cinnamomum, Illiciurn, Carpinus, and Nyssa. (Amer.
Jour. Sci. [2] xxxii. 355.)
The plants of the Lignite bed of Lauderdale
(which is distinctly overlaid by the Claiborne
Eocene) " show the greatest affinity with species of our time, and are apparently
of as recent an epoch as the fruits of Brandon." (Lesquereux.)
2. Animals.
Among Protozoans, Rhizopods are very numerous in some of the
beds, as in the Ashley Eocene in South Carolina. The coin-shape
fossils, Nummulites and Orbitoides, especially species of the latter,
abound in the Vicksburg beds.
The Radiates comprise Corals and Echini partly of modern
genera. The Mollusks embrace species of Oyster, Venus (clam),
Chama, Area, Valuta, Oyprcea, and other modern genera, but no
Brachiopods except Terebratulids and Discince, and no Cephalopods
but species of Nautilus. There are numerous land and fresh-water
shells in the beds of the Upper Missouri region.
Of Articulates, there are Crabs and Insects of nearly all the modern
tribes, excepting the higher group among Crabs,—the Maioid, or
Triangular.
Vertebrates are represented by remains of Fishes. Reptiles, Birds,
and Mammals. The fishes are of the order of Teliosts. and the
family of Squalodonts among Sharks. The teeth of the latter
(see figs. 4G5-467, p. 277) are exceedingly abundant in both the
Eocene and Miocene ; and some of the triangular teeth of Carcharo-
don megalodon are six and a half inches long and five broad at base.
They are found at Gay Head, as well as in the States south and
Fig. 797 A.
Carpolitlies lirandonensis.
TERTIARY PERIOD.
515
southwest. The abundance of Sharks' teeth is proof of the great
numbers of sharks in the waters, and also of the durability of their
teeth. The age was the time of culmination of the order of
Sharks.
The Reptiles embrace species of Turtles and Crocodiles.
The Mammals, in this age of Mammals, have a special interest.
No remains have yet been found in beds of the Claiborne epoch:
but in the Jackson beds there are bones of one or more species of
Whale. The most common, called the Zenglodon cetoidcs, was pro¬
bably about seventy feet in length. The large vertebrae were
formerly so abundant over the country in Alabama that they were
used for making walls, or were burned to rid the fields of them.
Some of the larger vertebrae are a foot and a half long and a foot
in diameter. Fig. 808 A shows one of the yoZ-e-shaped teeth to
which the name (from C,svylov, a yoke, and odoiy, tooth) alludes. The
remains occur in Mississippi, Alabama, Georgia, and South Caro¬
lina ; and a species of the genus is found in the Tertiary of Europe.
The Titanotherium or White River beds of the Upper Missouri
are remarkable for the great variety of bones which they contain.
Remains of nearly forty species of extinct quadrupeds have been
already found, through the labors of Evans, Hayden, and other
explorers. According to the determinations of Leidy, they include
eight Carnivores, related somewhat to the Hyena, Dog, and Panther:
twenty-five Herbivores, among them two Rhinoceroses, and species
approaching the Tapir, Peccary, Deer, Camel, Horse; and four Ro¬
dents, species of the Mouse tribe.
The T'danothere (Titanotherium Proutii, fig. 816) is one of the Herbi¬
vores, having some relations to the modern Tapir, but more like
the extinct Anoplothere and Paheothere of the European Tertiary.
One of the teeth is represented, half natural size, in fig. 816. The
animal was twice as large as a modern horse or the largest Paris
Palaiothere, and probably stood seven or eight feet high. Its re¬
mains occur in the lowest bed of the series; and hence, although so
gigantic in size, it was among the earliest species of the Tertiary
lake-region of the Upper Missouri.
One of the Rhinoceroses (R. occidentalis Leidy) was about three-
fourths as large as the East India species, and another (R. Nebras-
censis Leidy) half as large. Among the Ruminants there were
several species of a genus called Oreodon by Leidy, intermediate
between the Deer, Camel, and Hog. Fig. 818 represents a skull of
one of them.
The Mammals of the Yorktown epoch from the beds of the At¬
lantic coast, as far as known, are only species of Whales, Dolphins,
51G
CENOZOIC TIME MAMMALIAN AGE.
Seal, and Walrus. Martha's Vineyard and other places on the
Atlantic coast have afforded bones of these species.
The Pliocene beds, or those of the Sumter epoch, in South Caro¬
lina, have afforded the remains of a Mastodon and Stag (Cervus). In
the Upper Missouri region exists the great cemetery of the epoch,
and it is nearly as wonderful as that of the earlier Tertiary. From
remains gathered mainly by Ilayden, on the Niobrara and on the
Loup Fork from North Branch to its source, and some other points,
Leidy has determined twenty-seven species of Mammals, all now
extinct. They include three species of Camel (genus Procamelus), a
family before unknown among either the ancient or recent animals
of America; a Rhinoceros (R. crassus) as large as the Indian species;
a Mastodon (M. mirijicus) smeller than the M. giganteus of the Post-
tertiary ; an Elephant, peculiar to the epoch (E. Imperator), larger
than the largest before discovered ; four or five species of the Horse
family, one of which was closely like the modern horse ; a species
of Deer ( Cervus Warreni); others near the Musk-deer of Asia ; species
of Oreo Jon; a Wolf, larger than any living species, and a small Fox,
besides four other Carnivores ; a small Beaver and a Porcupine. The
collection of animals has a strikingly Oriental character, except in
the preponderance of Ungulates.
Characteristic Species.
A. Claiborne Epoch.—1. Mollusks—(a.) Conckifcrs.—Fig. 798, Ostrca
sellxformis; 0. divarieata ; 0. Vomer; 0. panda; Pecten Li/elli; fig. 799,
Figs. 798-802.
J ig. 798, Ostrea sellsuformis; 799, Crassatella alta; 800, Astarte Conradi; 801, Cardita plani-
costa; 802, Tun itclla carinata.'
TERTIARY PERIOD.
517
Crassatella a/ta ; fig. 800, Astarte Conradi Dana; fig. 801, Cardita planicosta,
from Canada dc las Uvas in California, as well as cast of the Mississippi,
and Europe (C. densata Con.); C. Blandingii ; C. rotunda ; Card turn Nicolleti.
—(6.) Gastcropods.—Fig. 802, Turritclla carinata Lea; Cahjptrojihorns (Iiostcl-
laria) vclatits; Pseudoliva vctusta Conrad; Orbis Rote/la ; Natica JEtites Con.
(Californian, as well as east of the Mississippi); Anolax gigautca, Oliuella Ala-
bantenxix, Jfaryittella larvata, Vohttilithcx ( Valuta) patrona, Corbula gibbosa.—
(<.'.) Cephalopoda.—Nautilites Vaintxemi Con.
2. Vertebrates Fig. 405, p. 277, Lamna el cyans Ag.; fig. 407, Notidanus
prtmiyenius, from Richmond, Ya.
Brackish-water beds of the Ujipcr Missouri.—Figs. 803, 803 a, Corbula (Pota-
nioini/a) maetriformis M. & II. : fig. 804, Corbictda Intermedia M. & II.; fig.
805. Unto prisons M. & II.: fig. 800. Viripara retuxa M. & II.; fig. 807, Melanin
Figs. 803-808.
Oonchifers.—Figs. 803, 803 a, Corbula (Potamomya) maetriformis; 804, Gyrene (Corbieula)
intermedia; 805, Unio prisons. Gasteropods.—Fig. 806, Yivipara retusa; 807, Melania
Nebrascensis; 808, Yivipara Leai.
Nehrasrcnsis M. & II.; fig. 808, Viripara Leai M. & II. Also, among Verte¬
brate fossils, scales of Lepidotus ; bones of Turtles of the genera Trionyx, Emys,
Ctimpscwys ; a species of Croeodilus.
15. Jackson Epoch.—1. Radiates—[a.) Corah.—Flabelluin Warlcsii Con. ;
Endopaehtjs Maelurii Lea.—(b.) Eehiitodernts.—Species of Hcmiaster, Chjpeastcr.
2. Mollusks (a.) Coiteh if era (Species common to the Jackson and Vicks-
burg epochs are marked with a dagger ["f] ).— Vcnerieardia planicosta Con.;
V. rotitndaf Lea; Cardinal Nieotlcli Con.; Corbula bicarinata Con.; Le.da mid-
tilineata Con.; Callista sobrittaf Con.; C. imitabilis Coil.; Maetra fttncralaf
Con.; Psammobia lintea'\ Con. ; Narieida Limaf Con.—(b.) Gasteropods.—Ca-
lyptrepliants relutus Con.; Cypriea fenestra/is Con.; C. linteaf Con.; C. xphe-
midesf Con.; Conns torfilis Con. ; Gastridium vetustum C'on.; Jlitra Milliuijtoiii
Con.; Jf. duinosa Con.; Valuta dttinosa Con.; Nation Vieksbnryeiisis'f Con.;
Tttrbitiella HbVsonrj" Con. ; Dontaliuin Mixxixsijigiensrf Con.
3. Vertebrates—Teeth of Sharks.—Fig. 808 A, Tooth of Zeiajlodou
eetoides, natural size.
One-sixth of the species occur in the Yieksburg beds, and several in the
Claiborne.
C. Vicksburg Epoch.—1. Protozoans,—Rhizopods.—Fig. 813, Orbitoidcs
Mantel/i, small specimen.
518
CENOZOIC TIME MAMMALIAN AGE.
2. Radiates.—(a.) Corah.—Oculinci (Madrepora) Missisuippienais; 0. Vicka-
burgensis ; Turbinolia cauli/era Con.—[}>.) Echinodenns.—Fig. 810, Chjpeaster
Iiogersi
3. Mollusks—(a.) Conchifcrs.—Figs. 809, 809 a, Pecten Poulsoni; fig.
811, Ostrea Georgiana, one-fourth linear dimensions; 0. Vicksburgensis Con.;
Fig. 808 A.
Tootli of Zeuglodon cetoides (%).
fig. 812, Anomalocardia Miaaissippienais Con.; Barbatia Miesissippiensis Con.; B.
Lima Con.; Cardium diversnm Con.; Crassatella Miasissippieiiais Con.; Panopcea
oblongata Con.—(b.) Gasteropoda.—Fig. 814, Cithnra Jlfissiasippienaia Con.; fig.
815, Dentalium iliasiasippienae Con.; also twelve species of Plenrotomidce, four of
Triton, five of Mitra, etc.
TERTIARY PERIOD.
519
4. Vertebrates (a.) Fishes.—Teeth of Sharks.—Fig. 4GG, p. 277, Carcha-
rodon angustidens Ag.; C. megnlodon Ag.; Galeocerdo latidens Ag.—(h.) Rep¬
tiles.— Crocodilus macrorhynchus.
At Red Bluff there is a stratum between the Jackson and Vicksburg beds.
Figs. 809-815.
Fig. 809, Pecten Poulsoni; 809, a, section of same; 810, Clypeaster Rogersi; 811, Ostrea Geor-
giana(X 812, Anomalocardia Mississippiensis; 813, Orbitoides Mantelli; 814, Cithara
Mississippiensis; 815, Dentalium Mississippiense.
containing many species peculiar to it; 28 per cent, only are Vicksburg species,
while 6 per cent, are Jackson.
D. Fossils op the White River Group, Upper Missouri.—1. Mollusks.
—Land and Fresh-water shells of the genera Helix, Planorhis, Limnsea.
2. Vertebrates—(a.) Reptiles.— Tcstudo Culbertsonii Leidy ; T. hemi¬
spherical.i. T.Owcnih.) T. lata L.—(b.) Mammals.—Fig. 816, Titanotherium
Proutiih., one of the teeth,—the last posterior inferior molar,—half natural size.
According to Leidy, the genus most resembled the Anoplotherian Chalicothere.
Fig. 817, Rhinoceros Nebrascensis L., three posterior superior molars, left side,
natural size. Fig. 819, Oreodon gracilis L., skull, young animal, under side;
Oreodon Culbertsonii L.; also, according to Leidy, species of the genera Machse-
rodus (or Drepanodon), Hyxnodon, Amphicyon, Dinietis, Leptarctus, of Carni¬
vores; Anchitherium, IIipparion, Merychipp>us, of Solidungulates ; Agrioehccrus,
Poebrotherium, Dorcatherium, Lcptauchenia, Protomeryx, Merycodus, Camelops,
520
CENOZOIC TIME MAMMALIAN AGE.
Pig. 816.
Tooth of Titanotherium Proutii (X }■£).
Fig. 817.
Teeth of Rhinoceros Nebrascensis.
Fig. 818.
Orooihm gracilis.
TERTIARY PERIOD.
521
of Ruminants; Titanotherium, Elotherinm, Rhinoceros, Mastodon, Chceropotamus,
Leptockoerus, of Multungulates; Chalicomys, Iscliyromys, Palxolagus, Eumys, of
Rodents.
Dr. Evans states with regard to a jaw of the Titanotherium Proutii seen by
him, that it had a length along the range of the teeth of five feet; and that one
skeleton, as it lay imbedded, measured eighteen feet in length and nine feet in
height.
E. Yorktowx Epoch.—1. Mollusks. —Fig. 819, Crepidnla costata ; fig. 820,
inside view of the same; fig. 821, Yoldia Iimatula Say, also recent; fig. 822.
Figs. 819-822.
(1 asteropod.—Figs. 819, 820, Crepidula costata. Conchifers.—Fig. 821, Yoldia Iimatula;
822, Callista Sayana.
Callista Sayann ; Pecten decennaries ; P. Virgiw'aurs ; Cardinal Virginiannm ;
Mereenaria tridacnoides; M. capax ; Chania eorticosa ; Axinasa Tumulus ; A no-
no a Rnffini; also, among living species, Ostrea Virginiea, or common Oyster;
Venus mereenaria, or common Clam (recently referred to the new genus Mereena¬
ria, and named Mereenaria violaeea); Venus caneellata Muetru Midinia lateralis ;
Pecten concentricus; Lunatia Herns; O/iva litterafa ; .Vnssa Tritia trioittata, etc.
2. Vertebrates.—(a.) Fishes.— Careharodnn mcgalodon ; Ga.leoc.erdo latidens
Ag.; Hemipristis Serra Ag.; Oxyrliina liastalis Ag.—(h.) Mammals.-—Pal am a
prisea Leidy; B. palxatlantica L.; Delphinus Conrad) L.; Plioca Wymani
L., etc.
In the Miocene of Oregon, on the Columbia, there are numerous fossils, in¬
cluding remains of Cetaceans, Fishes, Crustaceans (Callianassa Orcgouensis
Dana), and nearly fifty species of Mollusks. None of the latter are of living
species: Nucula divaricata Con. closely resembles N. Cobboldiee Sowerby, of the
English Miocene; Lueina acutilineata Con. can scarcely he distinguished from
the recent Atlantic coast species L. contraeta Say, and Lunatia saxea Con. is
as nearly related to Lunatia Heros. (Conrad.)
In the Miocene of Ocoya Creek, California, occur teeth of Sharks of the genera
Eehinorhinus, Scymnus, Galeocerdo, Prionodon, Hemipristis, Carcharodon, Oxy¬
rliina, and Lamna, besides a tooth of a Zygobates. (Agassiz.)
522
CENOZOIC TIME MAMMALIAN AGE.
F. Scmter Epoch.—Mollusks—Fig. 823, Pecten (Amusium.) Mortoni, Ja-
nira hemiryclica Ravenel; fig. 824, Area (Scapharca) Mans; A. lienoea Say;
Sconsia Hodgii Con. ; fig. 825, Cyprcea Carolinensis Con.; C. Pediculua ; Goniu
Figs. 823-825.
Conchifers.—Fig. 823, Pecten (Amusium) Mortoni; 824, Area (Scapliarca) hians. Gastero
pod.—Fig. 825, Cyprasa Carolinensis.
adversarius Con.; Faseiolaria rhomboidea ; Iiuny con incite Conrad. These South
Carolina Pliocene beds contain, according to Tuomey and Holmes, nine species
of Echinoderms, while none are found in the Yorktown beds in Virginia.
Corals are rare in the beds of both the Sumter and Yorktown epochs.
G. Fossils of the Loup River Group, Upper Missouri Region, proba¬
bly Pliocene.—1. Mollusks—Land and Fresh-water shells of the genera
Helix, Plujsa, etc.
2. Vertebrates.—Bones of Turtles, genus Testudo ; of Mammals of the
genera, according to Leidy, Megalomeryx, Procamelus, Cervus, Rhinoceros, Mas¬
todon, Elephas, Hipparion, Merychippw, Equus, Castor, Felis, Canis.
2. FOREIGN TERTIARY.
I. Rocks : kinds and distribution.
The rocks of the Tertiary period in Britain and Europe include
the following subdivisions, beginning with the oldest (Lyell, Prest-
wich, Pictet) :—
1. Lower Eocene.—Britain.—(1.) Thanet sands, containing rolled flints,
etc.; (2.) Woolwich beds, clays and sands ; (3.) London clay and Bognor beds.
Europe.—(1.) In some places in France, flint breccia and conglomerate; (2.)
plastic clay and lignite.
2. Middle Eocene—Britain.—(1.) Bagshot and Bracklesham beds; (2.)
Headon Hill sands and Barton clay; (3.) Headon group; (4.) Osborne or St.
Helen's group ; (5.) Bembridge or Binstead beds, Isle of Wight. Europe.—Sois-
TERTIARY PERIOD.
523
sonnais sands and Nummulitic group.—(1.) Lower Calcaire Grossier or Glau-
conie Grossicre; part of the Bruxellian (Brussels) beds of Dumont; 1 and 2,
Upper and Middle Calcaire Grossier; 3 and 4, Gres de Beauchamp, Lsekenian
beds of Brussels, Calcaire Siliceux ; 5, Gypseous group of Montmartre, Calcaire
Lacustre Superieur. Nos. 1 and 2 are the Parisian A system of D'Orbigny; and
3, 4, 5, the Parisian B system.
3. Upper Eocene of Lyell: Lower Miocene of some authors.—
Britain.—Hempstead beds near Yarmouth. Europe.—Part of Terrain Tertiaire
Moyen, and Calcaire Lacustre Superieur and Gres de Fontainebleau; Lacus¬
trine of Auvergne; Limburg beds of Belgium, Bupelian, Tongrian, and Bolde-
rian of Dumont; Maguntian of Mayer; Mayence basin; part of Tile clay near
Berlin; probably the so-called Miocene of Mayence and Castcl-Gomberto; also
the fresh-water Molasse of the cantons of Yaud, Berne, and Argovie.
4. Miocene of Lyell.—Britain, no marine beds; Leaf-bed of Mull in the
Hebrides?; Lignite of Antrim?. Europe.— Upper Falilunian of D'Orbigny;
Fahluns, Touraine ; beds of Gironde and Landes ; part of Vienna basin ; Superga
Hill near Turin; Helvetian or marine Molasse, and Dertonian or Upper fresh¬
water Molasse of Mayer; systems Diestian, Vampinian, and Scaldisian of
Dumont.
5. Older Pliocene—Britain.—Coralline Crag and Red Crag of Suffolk.
—Subapennine strata; Upper massive beds of Montpellier; Hills of Rome;
Mount Mario, etc.; Antwerp and Normandy Crag; Aralo-Caspian deposits.
6. Newer Pliocene—Britain.—Norwich Crag, of fluvio-marine origin,
containing mostly shells of species now found in British seas, with some Mam¬
malian remains. Europe.—Sicilian Pleistocene formation, which covers nearly
half the island of Sicily; near the centre of the island, at Castrogiovanni, it has
a height above the sea of 3000 feet; the upper two-thirds of the whole are lime¬
stone, and the rest mainly sandstone and conglomerate, underlaid by marl or
clay.
The Pleistocene of Lyell, called also Newer Pliocene, includes the Drift epoch
and Cave deposits and bones which are a part of the Post-tertiary. The Upper
Eocene of Lyell is called Lower Miocene by some European authors, and the
distinction in the fossil plants between it and the Lower Eocene is so great
that there appears to be reason in the course. Lyell makes the Claiborne beds
equivalents of the Middle Eocene of Britain, and the Yorktown beds equivalents
of the Miocene; and this would place the Vicksburg beds on the same horizon
with his Upper Eocene.
The lowest beds of the Tertiary formation appear to be in part
made from detritus derived from the Chalk and its flints. The
beds of the next epoch in the Eocene are for the most part marine,
and have a wide distribution over Europe and Asia. They are
largely Nummulitic, many beds consisting almost wholly of the
thin, disk-shaped fossils called Nummulites. The beds of this era
occur in the London and Paris basins (Anglo-Parisian region).
They spread over parts of the Pyrenean and Mediterranean basins,
and many other regions in Europe, covering portions of the Pyre-
524
CENOZOIC TIME MAMMALIAN AGE.
nees, Alps (to a height of 10,000 feet above the sea-level), Apennines,
and Carpathians; they extend into Egypt (where the Pyramids
were in part made of Nummulitic limestone), through Algeria and
Morocco, over parts of Asia Minor, Persia, Caucasus, India, the
Mountains of Afghanistan, the southern slopes of the Himalayas,
and to a height of 10,500 feet in western Thibet. Later in the Ter¬
tiary, the beds were much less generally marine and more limited
in extent, showing an approximation to the existing era in the con¬
dition of the continents. Marine beds are not found either in the
London or Paris basins, though occurring near Tours and Bordeaux
in France, and in some other parts of Europe. In the Pliocene
epoch there was a limited return to marine strata in England; the
beds occur as littoral deposits, called Crag, near Suffolk and Nor¬
folk on the shores of the German Ocean.
The diversity of the beds in the Tertiary period is well shown in the Paris
basin formation. There is, first, a bed of plastic clay with lignite, containing
in some places Oysters (0. bellovacina) and a few other marine species, and in
other layers lacustrine shells, along with bones of the earliest quadrupeds of the
age; second, a series of beds of coarse limestone (Calcaire Grossier) with green
marls, abounding in some parts in Nummulites and other Rhizopods; contain¬
ing marine shells (over 500 species in all) in certain beds ; a mingling of species
of Cerithium with fresh-water shells in others, and also bones of Mammals;
third, over this limestone, a siliceous limestone containing a few fresh-water
shells ; fourth, Gypseous marls, well displayed in the hill of Montmartre, the
great repository of the bones of Eocene Mammals explored by Cuvier, and con¬
taining also remains of Birds, Reptiles, and Fishes, with a few fresh-water
shells; fifth, sandstone, Gres de Fontainebleau, marine in origin, and regarded
as of the same age with the lower part of the Molasse of Switzerland; sixth,
Upper Lacustrine, or fresh-water beds.
II. Life.
In the European Eocene the fossils are all of extinct species; in
the Miocene, 15 to 20 per cent, are living ; in the Older Pliocene.
40 to 50 per cent.; in the Newer Pliocene, Norwich Crag, 90 per
cent.; in the Sicily formation, 70 to 90 per cent.
1. Plants.
Protophytes were abundant, as in America: the well-known
Infusorial beds of Bilin in Bohemia have a thickness of 14 feet,
and are fresh-water Tertiary. Planitz in Saxony is another similar
locality.
The higher plants are mainly Angiosperms, Conifers, and Palms.
The isle of Sheppey is famous for its fossil fruits, and among
TERTIARY PERIOD.
525
them Bowerbank has distinguished those of 13 species of Palms,
showing that England in the Eocene was a land of Palms. In the
Tyrol, there are other Eocene beds containing palms; moreover,
out of 180 species of plants 55 were Australian in character, and
23 allied to plants of tropical America. In the Miocene, Palms
appear not to have reached so far north as England, and the forests
of Europe were less tropical in character. What is remarkable, a
much larger proportion of species than now were of North Ameri¬
can type, showing that while the Eocene vegetation of Europe was
largely Australian, the second or Miocene phase (including in part
at least the Upper Eocene of Lyell) was North American in type.
In the Pliocene the Flora embraces the modern types of Rose,
Plum, Almond, Myrtle, Acacia, Whortleberry, besides Maples,
Oaks, etc.
Eocene plant-beds occur also at Sotzka in Upper Styria, Sagor in Illyria,
Monte Cromina in Dalmatia; others referred to the Miocene epoch exist atBilin
in Bohemia; St. Gallen in Switzerland; (Eningen in Germany; at Parschlug,
Pohnsdorf, Leoben, Koflach, etc. in Styria; and at Swoszowice in Galicia.
Out of the 180 species from the Eocene beds of Ilaring, 55, according to Et-
tingshausen, arc Australian in type, 28 East Indian, 23 tropical American, 14
South African, 8 Pacific, 7 North American and Mexican, 0 West Indian, 5 South
European. The resemblance to Australia consists not merely in the number of
related species, but in their character,—the small, oblong, leathery-leaved Pro-
teacex and Myrtaceie, the delicately-branching Casuarinx, the Cypress-like spe¬
cies of Frenela and Cnllitris, etc. Only 11 species have their representatives in
warm-temperate climates.
In the Miocene of Vienna, of the 33 species described by Ettingshausen, 10
are North American in type, 2 South American, 6 East Indian, 2 Australian, 2
central Asiatic, 4 South European, 1 central European; 11 species are sub¬
tropical, and 13 warm-temperate. The species particularly related to those of
North America (its warmer portion) belong to the genera Fayus, Quercus, Li
quidnmbar, Lauras, Bumelia, Diospyros, and Andromeiiit.es.
The Pliocene Flora of Europe was strikingly North American in typo, as
Brongniart has shown. lie mentions as examples the following genera of tem¬
perate North America which do not now occur in Europe:—Taxodium, Comqi-
tonia, Liquidambar, Nyssa, Robinia, Gleditschia, Cassia, Acacia, Rhus, Juglans,
(ieanothus, Celastras, Liriodendron, Symplocos. Moreover, certain genera, as
that of the Oak (Quercus), which have numerous species in America, had many
in Pliocene Europe, but have few now.
2. Animals.
Rhizopods were as important and abundant in the Tertiary as
in the Cretaceous period. Among them the coin-shaped Nummulites
(see fig. 192, p. 1G4) contributed very largely to the constitution of
526
CENOZOIC TIME MAMMALIAN AGE.
some of the Eocene strata, especially the Middle Eocene, as has
been mentioned on p. 523.
In the Miocene, the genus Nummulites—already become extinct—is succeeded
by another, similar in the general form of the species, called Amphistegina.
Mollusks were far more numerous in species and individuals in
Europe than in North America. The number of kinds described
is about G000, while not over 3000 American are known. The
shells of some localities—as, for example, the Paris basin—often
have nearly the freshness of living species, excepting a prevalence
of a white color, the original tints being mostly lost. In general,
also, the approximation to the living species is close. There are
but few Brachiopods (about 40 against 200 in the Cretaceous), and
these are almost wholly of the genera Tcrebratula and lihynchorclla.
The Vertebrates are the species of highest interest. The order of
Teliosts, or common fishes, which began in the Cretaceous, was pro¬
fusely represented ; nearly 300 species have been named, while only
half a dozen or so of ordinary Ganoids, and twenty of Pycnodonts, are
known. The Pycnodont group is now extinct. Teeth of Sharks
are also common, and are like those of America in genera and
partly in species.
Among Reptiles there were many true Crocodiles,—eighteen or
twenty species having been described, to two or three in the Creta¬
ceous, and seven or eight in the Present period. Turtles were nu¬
merous ; over sixty species have been described, and the shell of
one Indian species of the Miocene—Testudo ( Colossochelys) Atlas—
had a length of twelve feet, and the animal a total of nearly twenty
feet. The feet must have been larger than those of a Rhinoceros.
The first of Snakes have been found in the Eocene. A species
twenty feet long, Palceophis typhceus, was discovered in the Brackles-
ham beds. Half a dozen species related to the common Black
Snake (Colubridee) occur in the Miocene.
The earliest remains of Birds in Europe have been afforded by
the Eocene. Out of a dozen species from the Paris basin, two are
web-footed and related to the Pelican, three Waders, one Phea¬
sant, two Perchers, one Owl, two of the Vulture tribe. l>,
The earliest Mammals of the age occur in the Lower and Middle
Eocene,—anterior to those of the Upper Missouri. The Eocene
species include from the beginning both Herbivores and Carnivores;
but the former greatly preponderate. The Early Herbivores are
mostly of the tribe of Pachyderms, and were allied more or less
closely to the Tapir (as the Palceothere and Lophiodon), and Ilog (as
the Ilyracothere and Chasropotamus); or partook of characteristics be-
TERTIARY PERIOD.
527
bween the Pachyderms and the Stag among Ruminants (as the
Anoplothere and Dichobune),—a far more graceful type of Mammal.
There were also Bats (genus Vespertilio), and Opossums (Didelphis),
besides some species of Rodents, the earliest of the tribe. Both
Britain and France had then wild beasts of the above-mentioned
kinds, although in the present age there are no Opossums out of
America. Didelphis is the only genus of the number now having
living species. There were no Edentates (species of the Sloth tribe)
in existence, as far as ascertained, although these are among the
lowest of Mammals.
The first discovery of Tertiary Mammals in any part of the world
was made by Cuvier. The bones were gathered in the vicinity of
Paris, and a large number of extinct quadrupeds came to a new
existence through his researches. Among these the Palceothere—so
named from nahaioc;, ancient, and Ogpiov, wild beast—is one of the most
Fig. 826.
characteristic. The largest species of the genus, Palccotherium mag¬
num (fig. 826), was of the size of a horse, and the smallest, P. curtum,
not larger than a sheep. The figure referred to represents the sup¬
posed outline of the animal as restored, drawn partly from the
known form of the modern Tapir. The Anoplothere was another
Parisian species ; it was of more slender form, and, like the Rumi¬
nants, it had but two toes, while the Palceothere had three. Another
kind, the Chceropotamus, had the habit of the Mexican Peccary.
Owen observes that the Eocene Mammals were in general re¬
markable for having that completeness and regularity in the teeth,
and regularity also in other parts, which belong to the typical form
528
CENOZOIC TIME MAMMALIAN AGE.
of Mammal. Thus, in the species mentioned there is the com¬
plete number of teeth, 44, as in Man, as shown in the formula for
3-3 l_l 4-4 3-3
the dentition: i 0, c , p - -, m —- = 44 (i signifying incisor,
o—o 1—1 4—4 o~o
c canine, p premolar, and m molar teeth); in the Anoplothcrc and
some other Eocene species (Dichodon, etc.) the series of teeth is
continuous without a break,—a character which is manifested only
by Mankind among existing Mammals. Moreover, the crowns of
the teeth in Dichodon are all of nearly equal height, as they are in
Man. (Owen.)
The Miocene species include a larger proportion of Carnivores
than the Eocene. There were Mastodons, Elephants, and the still
stranger Elephantine animal, the Dinothcre, besides new Tapir-like
beasts, Carnivores, Monkeys, Deer, and the first Edentates, but none
of the Bovine or Ox kind.
Fig. 827 represents the skull of the Dinothcre (Dinothcriinn giyan-
teurn), much reduced. The head carried a trunk like an Elephant,
and two tusks, but the tusks were
turned downward. The length of
the skull is 3 feet 8 inches. The jaws
have on each side five molar teeth,
the first two answering to the poste¬
rior premolars. There is a mixture
of the characteristics of the Ele¬
phant, Hippopotamus, Tapir, and
the marine Manatus (Dugong), in
its skull ; and, as the bones of the
limbs are unknown, authors are not
agreed as to its relation, some ar¬
ranging it near the Elephant, and
others making it a swimming Mam¬
mal like a Dugong, 15 or 20 feet
long. One fine skull was dug up at
Epplesheim in Germany, and the remains have been found in
France, Switzerland, and a few other regions.
As the Sloth tribe is now confined to other continents, it is an
interesting fact that, in the course of the Miocene, Europe had its
species, the Macrothere, which was related to the African Pangolin
(the Ant-eater) but was six or eight times its size.
All the Fishes, Reptiles, Birds, and Mammals of the Tertiary are
extinct species.
The best known localities of fossil fishes are Monte Boloa, near Verona, in
northern Italy, of the age of the Nummulitic beds or Middle Eocene; canton
Fig. 827.
Dinothcrium gigantenm (X 4b)-
TERTIARY PERIOD.
529
of Glaris in Switzerland, in hard black slate, probably of the same epoch; Aix
in Provence, and also in Auvergne, of the Upper Eocene or Lower Miocene; at
Turin, Touraine, Vienna, Germany, etc., of the Miocene ; ffiningen, of the Plio¬
cene; also at Mount Lebanon in Asia Minor, of the early Tertiary.
The earliest Mammalian genera of the Eocene are Coryphodon Owen, an
Herbivore (or Ungulate), and Palieocyon, a Carnivore (or Unguiculate); they
are from the lower Plastic clay of England and France. Pliolophua Owen, is
another genus from a bed overlying the London clay ; it is a hoofed Herbivore.
Some of the Paris basin genera are Palieotherium, Anoplotherium, above men¬
tioned; also Dichobune and Xiphodun, near Anoplotherium, Tupirotherium and
Lophiodon, closely related to the Tapir; Cheer opotamux, having some of the cha¬
racters of the Hog; Hyxnodun, Carnivorous; Didelqjhis (Opossum, a Marsupial);
Venpertilio (Bat).
The genus Lophiodon is peculiar to the lower part of the Parisian formation
(Parisian A, p. 523), in which it occurs with two species of the genus Dichobune ;
the other genera mentioned were found in the Upper Parisian beds (B) or Mid¬
dle Eocene. In beds elsewhere of the former epoch occur also the genera Hyra-
cotherium and Heterohyns, of the Hog family or Suillids; Propalieotheriiim,
Puehynolojius, and Anchilopus, near the Tapir; and Hulitherium, related to the
Dugong. Some of the other genera of the latter epoch (called sometimes the
Palmotherian) are Cynodon, of the Carnivores; Paloplotherium, of the Palaeothe-
rian family; Xiphodon, Dichobune, of the Anoplotaerian ; Anchitherium, of the
Solidungulate or Horse family; Plesiaretomys, Adelomya, of Rodents; etc. (These
details and the following are cited mainly from the 4th volume of Pictet's Palaeon¬
tology.)
The Auvergne beds, between the Eocene and Miocene in age, contain more
Carnivores in proportion, besides more modern genera. Among them there are
Machanndus, Hysenodon, Cynodon, Cain'st, Amphicyon, Viverra, of the Carnivores;
Pnlxotherium, Tapirus, Anthracotherium, Hyopotamus, Rhinoceros, of Pachy¬
derms; Erinaccus, of Insectivores; Archeeomys, Mas, Castor, Steneojiber, Lepus,
of Rodents, etc.
Some of the Miocene genera arc Pliopitheeus, Dryopithecus, of Quadrumana;
Machserodus, Felix, Hyxnarctos, Hyrena, Canis, Viverra, Mux tela, of Carnivores;
Mastodon (M. longiroxtris, M. tapiroides, etc.), Elephax, Rhinoceros, Lixtriodon,
Sits, Anchitherium, Hippolheriiini, Eqnus, Hipp>upolamus, of Pachyderms ; Ca-
nielopardalis, Antilope, Cervux, of Ruminants; Dinotherium; Erinaceus, Talpa,
of Insectivores; Halitherium, Sqnalodon, Pliyseter, Delphinns, of Mutilates.
A few of the Pliocene genera, in addition to the modern ones already enume¬
rated, are Pithecns, Semnopithccux, of Quadrumana; Machxrodux, Ursns, Phoca,
of Carnivores; Lepits, Putorius, Arctomys, Layomys, Arvicola, Castor, of Ro¬
dents; Tlalsena, Balsenodon, of Mutilates.
The Tertiary Mammals of the Siwalik Hills, India, from beds supposed to be
Miocene, include, besides Quadrumana, species of Hyxnarctos, Flytena, Felix;
Elephax (7 species), Mastodon (3 species), Rhinoceros (5 species), Hippotherium,
Eqnus (3 species), Hippopotamus (4 to 7 species), Sits (3 species), Anoplotherium,
Chalicotheriuni, Merycopotamus, Camelux, Camelopardalis; Sivatheriuin, A nti¬
lope, Moschus, Oris, Eos (several species); Dinotherium ; Hystrijc. The Siva¬
theriuin was an elephantine stag, having four horns and probably a long pro-
35
530
CENOZOIC TIME—MAMMALIAN AGE.
boscis, being in some points between the Stags and the Pachyderms. It is sup¬
posed to have had the bulk of an elephant and greater height. Bos and the
related genera probably occur nowhere earlier than the Pliocene and Post-
tertiary.
General Observations.
1. American Geography.—The general form of the North Ame¬
rican Continent on the east during the early part of the Tertiary
period is shown by the distribution of the areas covered by marine
beds on the map, p. 133. From such data the following map has
been constructed. The Atlantic border was submerged nearly as in
Fig. 828.
the Cretaceous period; there was no Delaware or Chesapeake Bay, and
no Peninsula of Florida. The Mexican Gulf spread far beyond its
present limits north and west, but not over the Rocky Mountain
slopes as in the preceding era. The Ohio and Mississippi were barely
united at their mouths, if not wholly disjoined. Owing to the ele-
TERTIARY PERIOD.
531
vation of the mountain-region westward, the Missouri and other
streams rising in the mountains had begun to exist.
Yet the elevation of 6000 or 7000 feet, which began after the
Cretaceous, was but partly completed; the rivers were therefore
smaller than now, and the region, as Hayden rightly infers from
the great fresh-water Tertiary deposits, was covered by one or more
vast fresh-water lakes. The transition from the salt-water sea of
the Cretaceous to the emerged condition of the land in the Tertiary
is marked in the brackish-water deposits which lie at the base of
the series.
After the close of the Vicksburg epoch, referred to the Upper
Eocene, there appears to have been a further reduction of the
Mexican Gulf; for the Miocene and Pliocene beds are not recog¬
nized on its borders, unless very near the sea.
The Atlantic Tertiary region must have remained submerged
until after the Miocene era. The absence from most parts of the
coast of deposits that can properly be identified as Pliocene is a
remarkable fact, and seems to show that the continent during the
Pliocene era had at least its present breadth along the larger part
of the Atlantic coast, if not a still greater eastward extension.
The change of water-level causing this enlargement of the area
of dry land was probably not confined to the border of the conti¬
nent, but was part of a general change in which a large part of the
continent partook, especially the Rocky Mountain regions of the
West, and sparingly the country south of the Appalachian region,
or northwest of Florida. As to the latter, there is definite proof of
elevation in the present height of the Tertiary in parts of Georgia
and Alabama; for while in general the beds on the Gulf border
are but 100 to 200 feet above the sea, near Milledgeville, Georgia,
they are now 600 feet, and near Montgomery about 800 feet. The
position of the region, in a line with the general trend of Florida,
suggests that its elevation may have been connected with that of
the Peninsula of Florida itself. Moreover, the northwestward trend
corresponds with that of the Rocky Mountain region, which was in
process of elevation through the Tertiary, or after the Mesozoic,
and not with that of the Appalachian chain, which was raised
mainly soon after the Palaeozoic.
With regard to the Rocky Mountain region, the great thickness
over it of the Miocene and Pliocene shows a prolonged continua¬
tion of the lacustrine condition of the great area, and renders it
altogether probable that the mountains did not attain their full
altitude until late in the Tertiary period. The deposition of the
Lignite formation of the Eocene appears to have been followed by
532
CENOZOIC TIME—MAMMALIAN AGE.
an elevation through some part of this altitude. This is shown, as
Hayden observes, in the displacements which the Eocene beds
have undergone, especially in the vicinity of the mountain-ridges
about the summits of the mountains, and in which the Miocene
did not to an equal extent participate.
West of the Black Hills, according to this author, the dip is 5 to 10 degrees.
Along the Big Horn Mountains there is a similar dip, and in some places even
greater. Between the western extremity of these mountains and the North
Platte the beds are nearly vertical, so that the harder sandstone layers stand in
projecting lines over the surface, the softer intermediate clayey layers being
worn away. Along the Laramie range, and the Wind River Mountains, also,
the strata are more or less inclined. The Wind River beds, which are supposed
to succeed to Lignite formation (p. 510), also partook in the dip, though to
a less amount; and this is part of the evidence in favor of their being earlier in
age than the White River or Titanothcrian beds. The latter are but slightly
disturbed, if at all.
The White River (Miocene) beds occur, however, high up on the
mountain-slopes, showing that they have participated in a more
recent elevation. And it is probable that some 1000 or 2000 feet,
at least, of the altitude were added to the height of the summit
after the Miocene era.
On the Pacific coast in Oregon and California there is evidence, in
the present height of the Miocene beds, of an elevation of 1500 to
3000 feet after the Miocene era.
The alternation, in the Eocene of Mississippi, of Lignite beds with
those containing marine shells indicates an alternation of condi¬
tions in the course of the progress of the formations which were due
either to oscillations of level in the waters, or to the damming up
and breaking away of coast-barriers: through such catastrophes
the marine species probably met with that more or less complete
extermination which intervened between the Claiborne, Jackson,
and Vicksburg epochs. Sharks, having the free ocean to escape
in, underwent less change of species through the Tertiary period
than animals of other kinds. The remains of the Zeuglodon are so
widely distributed over the Gulf-border Tertiary, and so abundant,
that nothing less than a sudden elevation of the land in the Jack¬
son epoch, or the rush inland of a great earthquake-wave, could
have produced the effects observed.
The North American Continent, which since early time had been
gradually expanding in each direction from the northern Azoic,
eastward, westward, and southward, and which, after the Paheozoic,
was finished in its rocky foundation excepting on the Atlantic and
Gulf borders and the Western Interior region, had reached at the close
TERTIARY PERIOD.
533
of the Tertiary period its full expansion; and even these border
regions received afterwards but small additions. The progress
from the first was uniform and systematic; the land was at all
times simple in outline, and its enlargement took place outward
with almost the regularity of an exogenous plant.
2. European Geography.—In the earliest epoch of the Tertiary
in Europe there appears to have been, as has been observed by
others, first, an emergence of the land from the Cretaceous seas,
when the Chalk formation was eroded at surface and a flint con¬
glomerate in some places formed. • It may be that the land emerged
at that time to a considerable elevation, and that this emergence
occasioned in part the cold climate and cold oceans alluded to on
p. 504 as the cause of the extinction of Cretaceous species. The
return of the land to the sea-level, and in some places beneath it,
would commence the formations of the marine and estuary Tertiary
of the succeeding epoch; and a still more general submergence
would bring about the state when the great Nummulitic beds of the
Middle Eocene were forming over so large a part of Europe, Africa,
and Asia, even over regions which are now occupied by the lofty
mountains of these continents. At this epoch Europe was again an
archipelago, as in the Cretaceous period. The Paris basin was one
of its great estuaries, varying between fresh and marine waters
with changes of level and changing barriers.
After the Eocene, in Europe (as well as in America), the marine
deposits had much smaller extent, and the continent was mostly
dry land. But the ocean-border, instead of having the American
simplicity, had numerous deep indentations and winding estuaries.
The elevation of the Pyrenees took place in the Middle Eocene,
after the accumulation of the Nummulitic beds ; and the same was
true of the Julian Alps, and of the Apennines, Carpathians, and
other heights in eastern Europe. The Nummulitic strata have
now a height of 10,000 feet in the Alps, and 9000 in the Pyrenees.
The elevation of the chain of Corsica, and some minor disturbances
in Italy and other parts of Europe, are referred to the close of the
Eocene. The western Alps,. ranging N. 26° E., which include
Mt. Blanc, Mt. Rosa, etc., were raised, according to Elie de Beau¬
mont, after the deposition of part or all of the Miocene; for the
Molasse of this region was raised or disturbed by the uplift, and
not the Pliocene. The elevation of the eastern Alps from Yalais
to St. Gothard along the Bernese Alps and eastward to Austria,
ranging E. 16° N., is attributed by the same geologist to the close
of the Pliocene, as it lifted the Pliocene but did not disturb the
Post-tertiary. Even in the later part of the Pliocene era there was
534
CENOZOIC TIME—MAMMALIAN AGE.
an elevation of 3900 feet in a part of the island of Sicily (p. 523).
Thus, throughout the Tertiary period, the continent was making
progress in its bolder features over the surface, as well as in the
extent of dry land ; and the evidence is sufficient to show that
when the period ended, the continents had their mountains raised
in general to their full height.
3. Climate.—The climate of North America during the Early
Tertiary is fully indicated by the abundant fossil plants of the Lig¬
nite beds. Among the genera mentioned on p. 514, Sapindus, Pla¬
nera, Cinnamomum, Ficus, and Sabal belong to a warm climate; and
taken in connection with the other genera they indicate a mean
atmospheric temperature near that of the Dismal Swamp in North
Carolina. (A. Gray.) This corresponds to the warm-temperate zone,
and to the year-isothermal of 60° F. This isothermal in the West
passes through Fort Smith (near the meridian of 94° W.) on the
Arkansas River, and terminates on the Pacific near Los Angeles,
after a long and narrow northward bend in California nearly to the
Shasta Peak. Plants of these kinds were growing together in the
Eocene forests of the Upper Missouri, where now runs the isother¬
mal of 45°,—a line which passes close by the north shore of Lake
Ontario, down the St. Lawrence to Montreal, then south through
Vermont and east through southern Vermont and New Hampshire
to Portland, Me. It follows thence that the climate along this
line was warm-temperate.
Brandon, Vermont, is upon the line, and, in accordance with the
fact, the plants of the Lignite (p. 510) include Sapindus, Cinnamomum,
and Illicium, indicating about the same temperature, and confirming
the view that the Brandon and Upper Missouri species belong to
the same part of the Tertiary.
With regard to the plants of the later Tertiary, little is known.
The animals of the Pliocene in the Upper Missouri region include
Camels and other kinds characteristic of the warm-temperate zone;
so that there is no sufficient evidence that the climate was cooler
than in the Eocene.
Europe evidently passed through a series of changes in its cli¬
mate from tropical to temperate. According to von Ettingshausen,
the Eocene flora of the Tyrol indicates a temperature between 74°
and 81° F. and the species are largely Australian in character.
The numerous palms at the same period in England correspond to
a climate but little cooler.
The Miocene flora of the vicinity of Vienna the same author pro¬
nounces to be subtropical, or to correspond to a temperature between
68° and 79° F.; it most resembles that of subtropical America.
POST-TERTIARY PERIOD.
535
Farther north in Europe the flora indicates the warm-temperate
climate characterizing the North American Tertiary, and it is also
prominently North American in its types.
The difference in climate between North America and Europe is
fully explained if we suppose that in the former after the Creta¬
ceous period an increase in the extent of the polar lands took
place; for this would have given all the coolness to the climate
that the facts require. This is not a mere supposition ; for (1) the
elevation of a large part of the continent above the ocean beyond
doubt took place at that time (p. 533) ; and (2) no Tertiary rocks
have been observed in the Arctic to prove a submergence there in
that period, although Post-tertiary beds (proving a later submerg¬
ence) are widely distributed. The extension of the American con¬
tinent into the Arctic Zone is a prominent source of the existing
difference of climate between it and Europe.
It is not surprising, therefore, that central North America should
have passed at once to a warm-temperate climate, while Europe,
although situated in higher latitudes, should have had in succession
a tropical, subtropical, and temperate climate. Admitting this ex¬
planation, we understand why the Eocene plants of America are
analogous to the Miocene rather than to the Eocene of Europe.
II. POST-TERTIARY PERIOD (20).
Hitherto, through the ages to the close of the Tertiary period,
the continent of North America had been receiving a gradual ex¬
tension to the southward, spreading itself southeastward on the
Atlantic side and southwestward on the Pacific. The scene of
prominent action here changes, and in the Post-tertiary the great
phenomena are mainly northern. The same general fact is true for
all the continents, north and south: the changes affect most de¬
cidedly the higher latitudes of the globe.
The Post-tertiary period in America includes two epochs:—
1, The Glacial, or that of the Drift; 2, the Champlain. Next
follows (3) the Terrace epoch,—a transition epoch, in the course
of which the peculiar Post-tertiary life ends and the age of Man
opens.
1. GLACIAL EPOCH.
American.
Material, Phenomena, and Distribution of the Drift.
Drift.—The term Drift, as it is commonly employed in Geology,
includes the gravel, sand, or stones, occurring over some parts of
536
CENOZOIC TIME—MAMMALIAN AGE.
the continents, which are without stratification or order of arrange¬
ment, and have been transported and distributed without the
agency of rivers. The loose, unstratified gravel and boulders over
New England, New York, and the States west over the same lati¬
tudes is called drift. In some exceptional cases it is in layers; and
it is then called modified drift.
Age of the Drift.—The old unstratified Drift in North America
never covers the river or lake alluvial terraces, either the upper or
lower, nor the elevated sea-beaches, and therefore preceded in
origin the formations of the Cham plain and Terrace epochs. Sec¬
tions have been observed in many parts of New England, Canada,
the region about Lake Superior, and elsewhere, confirming this
statement.
General geographical distribution of the Drift.—The Drift occurs over
nearly all Canada, New England, and Long Island, either in view
or beneath the alluvium of the river-valleys. From New England
it stretches on westward over a broad range of country reaching
beyond the Mississippi, having its southern limit near the parallel
of 39° in southern Pennsylvania, Ohio, Indiana, Illinois, and Iowa,
while its northern is undetermined. South of the Ohio River it is
hardly traceable. Few boulders are found about Baltimore and
Philadelphia, and these not on the higher lands. It is thus north¬
ern in its distribution, and, though mere gravel, sand, and stones,
the travelled mass has a vast extent over the northern portions of
the continent. It is underlaid by clayey deposits in some regions.
Distribution in elevation.—While covering the lower country, the
Drift extends high up the mountains,—to an elevation of nearly
6000 feet on Mount Washington, 2000 or more on the Green Moun¬
tains, 3000 on Monadnock. Boulders small or large are found on
the summits of most of the elevations of New England under 3000
feet,—as on Mount Holyoke and Mount Tom.
Filling of river-valleys.—River-valleys in some cases were filled by
the Drift, so that the river, when again in action, had to reopen its
channel or make a new one. There is an old gorge of the Niagara
River, commencing at the whirlpool, which is thus filled. The
stream afterwards opened for itself a new gorge through the solid
rocks. This may seem strange: but water has power only when in
motion ; and it will consequently leave its banks of earth uninjured
and wear its way through rocks, if the slope favor it. Other similar
cases in New England have been described by Hitchcock.
Material of the Drift.—The material varies from fine sand and
gravel to coarse rounded stones or boulders, such as are strewed
thickly over much of New England and New York. The boulders,
POST-TERTIARY PERIOD.
537
while usually not exceeding a cubic foot in size, sometimes contain
a thousand cubic feet, and occasionally over twenty thousand.
One boulder in Bradford, Mass., is 30 feet each way (Hitchcock), and weighs
not less than four and a half millions of pounds. Another, in Whitingham, in tho
Green Mountains of Vermont, is forty-three feet long and thirty-two in avcrago
width, and full 40,000 cubic feet in bulk. It lies on the top of a naked ledge.
Manjr on Cape Cod are twenty feet in diameter, and one at V inch ester, 2f.II., is
twenty-nine feet across. In the Lake Superior region, and also in Ohio, boulders
of native copper have been found.
Drift without marine fossils.—The Drift has afforded no proof by
means of shells or other marine relics that it is of marine origin.
It contains occasional pieces of wood, but nothing that can be
traced to the ocean or suggests that it was formed under salt
water.
Arrangement of the material.—The material is coarsest to the north,
and becomes gravel and sand merely, without stones, towards the
southern limit of the Drift region. Nearing this limit, it stretches
somewhat farther south in the valleys than on the hills.
Courses of Drift sometimes not conforming to the courses of existing slopes
or valleys.—The stones sometimes lie in long trains, as in Richmond,
Berkshire co., Mass., and Huntington, Vt., crossing hills and val¬
leys, without following the line of slope ; or going obliquely across
a valley, as if the valley were neither an impediment nor guide to
the movement ; or the stones of one ridge are found on another
ridge separated from it by a deep valley.
The great, mass of gneiss at Whitingham, Vt., was probably transported
across Deerfield valley, the bottom of which is 51)0 feet below the spot
where it lies (Hitchcock). A block of granite nearly as large lies on Hoosac
Mountain, on the face overlooking a valley thirteen hundred feet below,—that
between Stamford and Adams,—which it had probably crossed. Such examples
are numerous.
Source of the material.—The Drift (1) is derived from the rocks to
the north of where it now lies, mostly between northeast and north¬
west; in New England, mainly from the northwest, or between
north and northwest; and (2) it has been transported to a distance
generally of twenty to forty miles, but sometimes also sixty or one
hundred miles. The distance is ascertained by comparing the rock
of the boulders with the rocks of the country. The granite, gneiss,
and syenite boulders of southern New England have been traced
to their original beds, somewhere northward of them.
The iron-ore bed of Cumberland, Rhode Island, furnished boulders for the
country south to Providence, thirty-five miles, while none are found to the
northward. (Hitchcock.)
538
CENOZOIC TIME MAMMALIAN AGE.
In southwestern Vermont the granite of a high hill between Stamford and
Pownal, which is almost as high as the Green and Hoosac Mountains lying to
the east and southeast, has been carried southeastwardly over the western sides
of these mountains, and over a very hilly region, into and nearly across the
State of Massachusetts.
Large boulders strew thickly the north shores of eastern Long Island, which
are the crystalline rocks, trap, and sandstone of New England. Southern New
York is strewed with pebbles and boulders of the Azoic rocks to the north.
South of Lake Superior there are boulders which have come from the north
shore of the lake.
Attendant phenomena,—Groovings or Scratches.
Besides the travelled stones and earth, there are deep scratches
or groovings in the rocky surface of the country across which the
stones were carried, over the regions of quartz, slate, and other
rocks not undergoing easy decomposition in New England, New
York and other parts of the country. The rock when uncovered
Fig. 829.
Drift groovings, or scratches.
is often-scored all over with these groovings. The very hard quartz
rock of Vermont and New York was not able to resist the powerful
agent.
Character of the grooving and wear of rocks.—The groovings are (1)
long, straight, parallel lines, often like the lines of a music-score,
or broad scrapings, ploughings, and gougings of the surface.
The scratches vary from fine lines to furrows half an inch deep,
and occasionally occur a foot deep and several feet wide, as at
Rowe in Massachusetts, or even two feet deep, as on the top of
POST-TERTIARY PERIOD.
539
Monadnock (Hitchcock). They are (2) thickly crowded over
large areas, as if the whole had been under friction from a mass of
material which spread over and covered it. At the same time,
(3) the variations from broad smooth planings and ploughings to
deep groovings and fine scratches show variations in the moving
mass. Also (4) the channels are sometimes made of broken lines,
or a succession of slight curves, as if from hitches in the progress
of the gouging agent; and, coming to the edge of a layer where
there was a sudden descent, they have occasionally chipped it off,
as if the heavy body had gone down with a jump.
Again, (5) broad surfaces have been smoothed or polished by the
same agency, and exposed rocky ridges have been rounded, pro¬
ducing smoothly rounded knolls or hummocks, like what are called
rochcs moutonncs in the Alps.
Direction of the groovings.—Again, (6) the groovings have a general
southward direction, varying mostly between S. 20° W. and S. 20° E.
In New England the most common course is about S. 10° E. In central
Massachusetts, between S. 8° E. and S. 15° E.; in eastern, about S. 20° E.; in
the Berkshire Mountains, S. 50° E.; about Mount Washington, S. 18° E.; in
Vermont, S. 20° E., but varying between S. 67° W. and S. 85° E., or, omitting
exceptional cases, between S. 15° W. and S. 35° E. On the west side of the
Green Mountains the course is mostly within a few degrees of north and south.
It is the same in eastern New York.
In Maine the courses have an unusual amount of easting. According to the
observations published in the Geological Report of C. H. Hitchcock, sixty-six in
number, they vary between S. 67° W. and S. 85° E., but excluding three, be¬
tween S. 75° W. and S. 40° E.; and about a fourth of all are between S. 55° E.
and S. 85° E.
In western New York the course is mostly southwest; in Ohio, generally
southeasterly, and the same in the larger part of Michigan and Illinois; in
Iowa and Wisconsin, and over the country to the Lake of the Woods, from the
northward. In northern Michigan the courses vary between W. by S. and S.W.
Two or more sets of groovings.—There are (7) frequently two or three
sets of groovings, differing a little in direction. Thus, in western
New York there is, in addition to the northeast system, a subor¬
dinate north and south system (Hall). On Isle La Motte in Lake
Champlain there are eight sets (Adams), although usually not over
two or three in Vermont.
Groovings on elevated summits.—Again, (8) the scratches are found
on the heights as well as lower lands. They occur to a height of
5000 feet on the Green Mountains (C. H. Hitchcock); on the top of Jay
Peak, 4000 feet high (Adams); on the top of Monadnock. In
some instances (9) the wear and scratches are most decided on the
north side of elevations. Professor Hitchcock has observed that
540
CENOZOIC TIME MAMMALIAN AGE.
Mount Monaclnock in New Hampshire, 3250 feet high, is scarified
from top to bottom on its northern and western sides, but not on
the southern.
Relation, of groovings to the courses of valleys.—Again, (10) there is in
general no conformity between the direction of the slopes of the
minor valleys or declivities and the courses of the groovings. This
is obvious from the fact of a prevalent direction.
There are, however, exceptions. At Jonesville, Vt., the three courses S. 50°
E., S. 56° E., and S. 76° E. intersect one another, and, according to C. II. Hitch¬
cock, they vary in direction with the windings of the valley, though strongest
on the northwest side of the valley. Several other cases arc mentioned in the
Geological Report on Vermont where the scratches correspond to the course of
a valley.
But, (11) taking into view the fact that the great valleys of New
England and eastern New York run north and south,—that is, the
Connecticut River and the Hudson River valleys,—it appears that
there is a conformity in these cases between the direction of the
valleys and the courses of the groovings. Along the borders of the
Connecticut the courses S. 20° E. to N. & S. are very common, as
well as over the country east and west.
Groovings on high summits.—(12) Groovings over the highest parts
of the summits in the Green Mountains on which they occur, were
inore easterly in direction, according to Hitchcock, than those over
the general surface below.
The follow.ing are a few examples :—On Mansfield Mountain, 4848 feet high,
the course is S. 30° E; on Jay's Peak, 4018 feet, S. 50° E.; on Camel's Hump,
4188 feet, S. 50° E.; Mount Holly, 1415 feet, S. 70° E.; several peaks in the
Hoosac range in Massachusetts, S. 55° E. to S. 80° E. Hitchcock also gives S.
30° W. as another course observed on Mansfield Mountain.
Aaain, (13) groovings are seldom found on the south side of the
higher summits.
Grooving of boulders.—Again, (14) the boulders and stones are
sometimes scored, as well as the rocks beneath them.
Drift in Foreign Countries.
The Drift presents the same characteristics on the other conti¬
nents as in North America. It is confined to the northern half of
Europe ; that is, Britain, Denmark, Russia, northern Germany, and
Poland, down to the parallel of 50°,—a line which has nearly the
same mean temperature now as the southern limit, o9°, in the
United States. In South America it is met with from Tierra del
Fuoao. as far towards the equator as 41° S.
POST-TERTIARY PERIOD.
541
The course of the stones, gravel, and sand in each case was
towards the equator.
In Europe, they crossed the Baltic from Scandinavia to Germany,
many of great size; and other Scandinavian rocks were carried to
the coasts of Britain. The general direction is from the north¬
ward, or between north and northwest.
The distance of travel varies from five or ten miles to five or six
hundred.
Scratches are also common in the Drift regions of Europe, and
are evidently part of the results of the Drift movement.
Fiord Valleys.
Another great fact that belongs to the Drift latitudes on all the
continents, and may have the same origin, is the occurrence, on
the coasts, of fiord valleys,—deep, narrow channels occupied by the
sea, and extending inland often for 50 or 100 miles. This geogra¬
phical connection with the Drift is a striking one. Fiords occur
on the northwest coast of Europe, from the British Channel north,
and abound on the coast of Norway. They are remarkably dis¬
played on the coasts of Greenland, Labrador, Nova Scotia, and
Maine. On the northwest coast of America, from the Straits of De
Fuca north, they are as wonderful as along Norway. On the coast
of South America, they occur in Drift latitudes from 41° S. Drift
latitudes are therefore identical nearly with the fiord latitudes.
General Observations.
Origin of the phenomena of the Glacial epoch.—The Drift epoch
is usually called the Glacial epoch, under the idea that ice, either
in the form of icebergs or glaciers, was concerned in the transporta¬
tion of the boulders, pebbles, and earth. Ice may float masses of
many thousand tons' weight, when in the condition of an iceberg,
for twenty, thirty, or hundreds of miles ; and so glaciers, as in the
Alps, may bear along great masses of rock or earth. But simple
running or moving water is comparatively feeble for such results.
There are, then, twro theories, the Iceberg and the Glacier. The
former supposes large parts of the continents under the sea; the
latter places the same regions above the sea, and perhaps at a
higher elevation than now. They thus diverge at the outset.
1. Iceberg theory.—(1.) The Tceberg theory supposes a submergence
in New England of 2000 to 4000 or 5000 feet. It requires that the
submerged area should have extended wherever the drift occurs;—
542
CENOZOIC TIME—MAMMALIAN AGE.
that it extended beyond this limit the facts give no evidence. It
therefore reached to the Ohio on the south, if not beyond, and
far to the north over the British possessions, to a limit north which
is yet undetermined.
It appeals, further, to the facts that—
(2.) The icebergs of the Atlantic are floated southward from the
Arctic, and come freighted with a vast amount of stones and earth ;
and that many of them at the present day descend along the coast
of Labrador and Newfoundland and over the Newfoundland
Banks, and, as they melt, cover the coast with blocks that are as
large as any of the Drift epoch, and also strew the sea-bottom with
both stones and earth.
(3.) The great Labrador current (p. 41) has the general direc¬
tion of the drift stones and scratches, or from the northward, and
must have always had this course.
(4.) The material deposited by melting bergs would be unstrati-
fied, and contain few if any sea-relics.
(5.) Stones in the foot or under surface of a grounded berg
would scratch the surface over which it might move.
(G.) Accumulations of sand and pebbles having a resemblance
to beach-deposits occur at different heights in Massachusetts from
800 and under to 2G00 feet,—the last in the White Mountains and
elsewhere (Hitchcock).
In the Iceberg theory there are the following difficulties:—
(1.) If any zone or part of the continent were under the sea,
we should somewhere look for that sure evidence, marine fossils.
But none have been found. One-half of the Pliocene species of
sea-shells still live ; and therefore the waters were not destitute of
life. The Tertiary and Cretaceous coasts are well marked by these
means on the Atlantic and Gulf borders. The shore of the sea of the
Drift period has not been traced by either beaches or shells. The
highest point of shore shell-beds known is 500 feet, and this occurs
on the St. Lawrence (p. 549): nothing of the kind occurs over the
Ohio region north or south of the river.
(2.) The icebergs of the Atlantic bring their burdens from the
Arctic, having gathered them while glaciers about the Arctic
mountains,—for all icebergs are fragments from the lower ends of
glaciers broken off and floated away by the sea; and they are
therefore not exactly parallel in their operations with the means
of transport over New England, where the stones and earth were
carried usually less than fifty miles. Consequently, if icebergs were
the means of transport in New England, those icebergs must have
commenced as glaciers about New England mountains,—an idea
POST-TERTIARY PERIOD.
543
which has its difficulty in the alleged fact (inferred from the
scratches and stones) that even Mount Washington was all sub¬
merged but a thousand feet, and Mount Monadnock to its very
top.
(3.) It seems very improbable that the scratches made by stones
in the bottom of bergs that chanced to be grounded, should score so
uniformly and completely the wide surface of a region. The cause
would rather make few and distant deep channelings, unless the
ice lay regularly over the whole bottom,—a condition which may
be that of the foot of a glacier where it enters the sea, but not that
of an iceberg.
(4.) The submergence of the northern part of America as far as
the southern limits of the Drift would make a warm climate for the
continent, and not a glacial period (p. 45) ; and hence there is
great difficulty in accounting for either icebergs or glaciers upon
this idea.
2. Glacier theory.—This theory is sustained on the ground—
(1.) That glaciers are known to transport boulders, gravel, and
earth down very gentle slopes as far as glaciers descend: the stones
and earth of icebergs were gathered when the ice was a glacier.
(2.) That the moving glaciers make scratches in the rocks be¬
neath them, and on boulders or stones, precisely like those of the
drift regions as to regularity, kind, number, and all other pecu¬
liarities ; and that polished and rounded surfaces are other common
effects from moving glaciers.
(3.) That glaciers will move on slopes of one or two degrees:
if the whole surface of a continent over the northern regions were
an immense glacier, a very little motion would produce in time
great results.
(4.) That the absence of marine relics and all sure evidences of
any sea-shores over the continent above a level of 500 feet above
the ocean is so far evidence that the sea did not cover the land in
the Post-tertiary period to a higher level than 500 feet.
(5.) That the fiords afford evidence of an elevation and widening
of the continents in the higher latitudes ; and, as fiord-latitudes and
drift-latitudes are the same, this epoch of elevation was, in all pro¬
bability, that in which the Drift phenomena were produced. This
evidence from fiords is based on the fact that the valleys which
they occupy must have been excavated, like most other valleys, by
the action of running water or ice, and this could have been done
only when the country along the sea-border was so raised that
they were occupied by streams and glaciers from the land instead
of the waters of the ocean. (See under Dynamical Geology.)
544
CENOZOIC TIME MAMMALIAN AGE.
The submarine valley of the Hudson River (p. 441) may have been formed
during the same elevation of the continent in which the fiords originated. The
Connecticut River valley is also distinct over the same submerged plateau, run¬
ning south from the channel east of Long Island.
(G.) That an elevation of the continent over its northern regions
of a few thousand feet is sufficient to account for the existence of
a Glacial epoch in the earth's later history ; and an elevation of
5000 feet is as probable as a subsidence of 5000 feet.
The main difficulty encountered by the Glacier theory is that the
land to the north has not the slope supposed necessary to give
glaciers a southward movement, and it would not acquire this
slope by any probable elevation.
During a Glacial epoch of the kind here supposed, the whole
northern portion of the continent down to the southern limit of
the Drift would have been covered by a vast and almost uninter¬
rupted glacier. This is now the case in North America with the
return of nearly every winter. But the depth, instead of being, as
now, but a few feet, and that mostly of snow, must have been,
judging from the height on the hills to which the striae extend, at
least 4000 or 5000 feet, and the material, as in all such thick accu¬
mulations, would have been ice; and above this there may have
been other hundreds of feet of snow. Glaciers of so vast extent
and thickness would have moved downward wherever the condi¬
tions would permit, like the glaciers of the Alps,—and all the more
readily for their enormous weight.
There are two conditions to be considered:—First, the one already
mentioned,—the existence of some degree of slope in the surface;
second, the absence of barriers to prevent descent along the slope.
Now, to the northward over the continent, with no lofty ranges,
there would have been a universal barrier in the ice and snow of
the universal glacier. But on the south the ice would have had a
limit, caused by the climate. Motion would therefore have been
mainly to the southward, if it took place in any direction.
The requisite slope exists now in New England and eastern New
York, along the Connecticut valley, east of the summit of the
Green Mountains, and along the Hudson River valley west of the
summit. The motion of a great glacier along either valley would
have given the same direction to the striae and to the lines of
boulders which actually exists. It would also have scored the
sides and tops of the minor valleys and ridges, regardless of their
courses and declivities; and as the glacier finally melted away it
might have left its moraines as trains of stones on the surface, cross¬
ing deep valleys obliquely, or in any direction, and blocks of thou-
POST-TERTIARY PERIOD.
545
sands of tons' weight might have been lodged on the tops of ridges,
miles away from their place of origin. Moreover, the Green Moun¬
tain side of the Connecticut valley would naturally have given that
more eastern direction to the strife observed about the higher sum¬
mits (p. 540), because the general slope is eastward; while below
these more elevated points the southward inclination of the great val¬
ley itself would have directed the movement of the extended glacier.
In the vicinity of Penobscot Bay, Maine, according to J. He Laski,
there are groovings, polishings, and other related effects, in perfec¬
tion, which prove beyond question the former existence there of
an extensive glacier,—probably one of the many terminations of
the continental glacier.
Switzerland, besides its examples of small modern glaciers, affords
evidence of a great glacier in some former time which serves to
illustrate the condition in the Glacial epoch in America. At the
time referred to (supposed to be later than the Glacial epoch), a
glacier stretched from Mt. Blanc and other Alpine heights over
the Swiss plains to the Jura Mountains on the borders of France,
having underneath it the sites of Lake Geneva, Lake Neufchatel,
and other Swiss lakes. The declivity of the Juras facing the Alps
was covered, to half its height in many places, with the boulders
that were transported by the ice; and one of them—the Picrrc-a-bot,
a mass of granite (or more properly protoginc)—is 02 feet long by 48
broad, and contains about 40,000 cubic feet, equivalent to a weight
of 3000 tons. The transportation of this and other such blocks has
been attributed to icebergs. But Guyot, by an extensive explora¬
tion of the mountains and plains, succeeded in tracing out the lines
of moraines across the plains; and, by observing the kinds of rocks
characterizing the several lines, followed each up to the peak or
peaks in the Alps from which it was derived. He proved in this
way that the Pierre-a-lot and other similar masses of the same part
of the Juras came from Mt. Blanc, and that the red sandstone
boulders accompanying the granitic on the Juras were from the
Aiguille Rouge, a neighboring summit. By this means he found
that the order of succession in the peaks is repeated in the order of
the lines of rocks over the lowlands, just as would have been the fact
had these lines been originally the moraines of a glacier. He fur¬
ther ascertained that the great glacier from Mt. Blanc which bore on
its surface for ninety miles the Pierre-a-lot, and multitudes of other
masses, small and great, left the vale of Chamouni (the present
terminus of the Mt. Blanc glaciers) by the valley of the Trient, and
so passed northward into the valley of the Rhone ; thence it spread
still northward and westward across the Lakes of Geneva and Neuf-
36
546
CENOZOIC TIME—MAMMALIAN AGE.
chatel to the Juras. The Alpine heights are in many places deeply
grooved, on a magnificent scale, to a height of 10,000 feet above
the sea (as well seen in the valley of the Aar), showing that this
was the height of the ancient glacier in the mountains,—while its
depth or thickness must have been 4000 or 5000 feet. The slope
from Mt. Blanc to the Juras back of Neufchatel averages very
nearly one degree,—equivalent to one foot in sixty. There are
other blocks in the Alps still larger than the Pierre-a-lot. One of
them, at Steinhof, near Seeberg, contains 01,000 cubic feet, and has
travelled from its original site nearly 200 miles.
These facts from Switzerland seem to be but a repetition of those
observed in connection with the Drift epoch in America and other
regions. They will be better appreciated after a perusal of the
pages on Glaciers under the head of Dynamical Geology.
The Glacier theory most satisfactory, hut the Iceberg theory required, in
some cases, for the borders of Continents.—In view of the whole subject,
it appears reasonable to conclude that the Glacier theory affords the
best and fullest explanation of the phenomena over the general
surface of the continents, and encounters the fewest difficulties.
But icebergs have aided beyond doubt in producing the results
along the borders of the continents, across ocean-channels like
the German Ocean and the Baltic, and possibly over great lakes
like those of North America. Long Island Sound is so narrow
that a glacier may have stretched across it.
In Europe icebergs were evidently more extensive in their opera¬
tion than in America. Glaciers have probably continued there in
action from the time of their first appearance on the continent to
the present day ; and the Glacial era on that continent may not,
therefore, be the well-defined period that it is in North America.
Geography.—The Glacial epoch an epoch of high-latitude elevation.—
The evidence presented with regard to an epoch of unusual cold in
the early Post-tertiary, when glaciers and icebergs prevailed vastly
beyond their existing limits, leaves little doubt that the epoch was
one of some increase of elevation throughout the drift or cold lati¬
tudes. The elevation may not have affected every part, but yet
was sufficient to make the northern and southern hemispheres
alike in their glacial phenomena. This evidence is strengthened by
the fact that fiords occur in the same latitudes, north and south.
The author's views on fiords and the epochs of the Post-tertiary
period were first published in the Amer. Jour. Sci. [2] vii. 379,
1849, and xxii. 325, 346, 1856.
See further, on Glaciers, Appendix F.
POST-TERTIARY PERIOD.
547
2. CHAMPLAIN EPOCH.
American.
The Ciiamplain epoch is so named from beds of the epoch on the
borders of Lake Champlain.
The term Champlain is applied to marine deposits of the epoch by C. H. Hitch¬
cock in the Report on the Geology of Vermont.
I. Rocks: kinds and distribution.
Distribution.—The distribution of the formations of the Champlain
epoch may be treated of under three heads: (a) river-border forma¬
tions ; (6) lake-border and other lacustrine formations; (c) marine
or sea-border formations.
(a.) River-border formations.—From New England to California and
Oregon, over the wide range of the continent, the river-valleys
contain extensive alluvial formations. The beds overlie the drift
of the Glacial epoch, where they occur together, as has been ob¬
served in several places ; and they generally reach to a height far
above that of present alluvial action. The Connecticut River,
Hudson, Mohawk, Ohio, Sacramento, Willamette, and numerous
other valleys afford fine opportunities for their study.
The formation along the course of any river has nearly a flat
summit, and is the foundation of the elevated plateau of the
valley; and very often there are plains at one or more levels besides
the upper, so that the whole makes a series of terraces.
The sketch on p. 548 (fig. 830), from the Connecticut River valley
some miles south of Hanover, N.II., represents the general appear¬
ance of the alluvial formation with its terraced surface. The de¬
scents of a road in the neighborhood of rivers are mostly from the
top of one of the tables down to the bed of a streamlet, the origin,
perhaps, of the cut; and the ascent on the opposite side carries the
road to the upper level again. The borders of all such cuts, there¬
fore, and of river-valleys generally, are excellent places for observ¬
ing the features of the alluvial landscape and studying its beds.
Up or down the stream, horizontal lines may often be traced for
miles, marking the limit of one or more of the several terraces bor¬
dering it. Many villages in the vicinity of rivers owe a large part
of the beauty of their sites to these natural terraces of the country.
This alluvial formation appears to characterize all the river-val¬
leys of the continent over the drift-latitudes, and also, to a less
extent, still farther south in the latitudes of Kentucky and Ten-
548
CENOZOIC TIME—MAMMALIAN AGE.
nessee, so that it may be said to have a continental distribution.
It is not yet ascertained whether it is distinguishable by greater
elevation from the present river-flats in the valleys of the States
bordering on the Gulf of Mexico.
It generally accompanies the whole course of a stream from its
mouth to its source in the mountains. It follows even all the tribu¬
taries, and fails only where the stream is a steep mountain-torrent
or is bounded by lofty walls of rock. A map showing the distribu¬
tion of the formation will hence be like that of the rivers, with the
Fig. 830.
Terraces on the Connecticut River, south of Ilanover, N.H.
same variations of course for each, excepting the minor irregulari¬
ties and a much greater breadth.
These valley alluvial beds contain no traces of marine relics, and
no evidence whatever of any but a fresh-water origin.
(b.) Lake-border and other lacustrine formations.—Formations similar
to those along river-valleys exist about lakes in the same latitudes.
They are often called beaches, or lacustrine formations. Where a river
flows into a lake, the elevated plain of the river-alluvium is gene¬
rally continuous with that bordering the lake.
It is not safe to conclude that all the upper lake-border forma¬
tions belong to the Champlain epoch, any more than that all elevated
sea-beaches containing recent shells are of the same. Yet in North
POST-TERTIARY PERIOD.
549
America these Champlain formations of all kinds over the continent
are so combined in system, both as to extent and elevation, that it is
generally not difficult to arrive at a right decision on this point.
There are many examples of the direct passage of the high plains
along a river into that of the lake, or into that of the sea-border,
where the river empties into the one or the other, in which the
mutual relations and dependence of the whole cannot be doubted.
Besides these border formations of lakes, there are also, overlying
the Drift in many places, beds of marl or calcareous earth formed
from fresh-water shells in the ponds and smaller lakes of the epoch.
This shell-marl is of great value as a fertilizer. Beds of peat were
often in progress afterwards in the same ponds as they were gradu¬
ally drained and became marshes. The shells are all of existing
species.
In elevated regions without rivers or lakes, beds of the formation
may sometimes be distinguished by a more or less perfect stratifica¬
tion or regular arrangement of the surface-gravel, indicating the
former action of water. Such beds are sometimes called beaches and
attributed to sea-shore action, although containing no evidence of
this origin from marine remains or other satisfactory marks. They
are also termed, with a degree of propriety, modified drift.
(c.) Sea-border formations.—On sea-shores, also, there are analogous
deposits, situated above the height at which accumulations are now
in progress. They often have the characters of the modern sea-
beach, and are then rightly termed ancient sea-beaches; and the ter¬
race, in such a case, about the mouths of rivers passes directly into
that of the river-border formation. In other places they resemble
more the shallow-water deposits of a coast. They often bear dis¬
tinct evidence of their marine origin in the presence of marine
shells. Such beds have been observed near Brooklyn on Long
Island, where they contain shells and have a height of one hundred
feet above the sea-level; at several places on the coast of New Eng¬
land ; on the shores of Lake Champlain, at different heights, up to
393 feet above tide-level, and containing shells to a height of 325
feet; on the borders of the St. Lawrence, with abundant marine
fossils; near Quebec, Montreal, and on the Ottawa, to a height be¬
tween 400 and 500; and beyond to Kingston. From this point the
same formations continue on, and border Lake Ontario, but they
are destitute of marine remains,—the waters of the river St. Law¬
rence beyond having apparently prevented the farther ingress of
the ocean and of marine life.
Similar beach formations, containing recent shells, occur in the
Arctic regions at various places, as on Cornwallis and Beechey
550
CENOZOIC TIME—MAMMALIAN AGE.
Islands in Barrow Straits, where they are at different heights, to
1001) feet above the sea.
Material of the beds.—The beds consist of loose earth or loam, clay,
gravel, and occasionally large stones. They may be either destitute
of lamination,—a very common characteristic,—or finely laminated
like the silt or clay of river-flats. They are sometimes partially
consolidated, though usually little more compact than the modern
alluvium. Some of the layers, especially those of clay, contain hard
concretions, in which carbonate of lime is usually the concreting
ingredient. The stratification, wherever observable, is horizontal
or nearly so, unless disturbed by the fall or undermining of masses.
Instances occur of contortions in the clayey layers in which the sandy beds
above or below do not partake. Such layers of clay, when thoroughly wet, will
readily become flexed from any laterally-acting pressure when the other beds
will only be compressed; and they have been known to be forced out altogether
under the superincumbent pressure of a high bank.
The surface of the upper alluvial plain is often excessively pebbly or stony,
because of the removal of the finer soil in which the pebbles or stones were
imbedded by the winds and rains. As the beds are soft, they are readily worn
away by both causes. In many regions the great plain is changed into a suc¬
cession of hills and ridges by the action of the rills and streamlets set in motion
by the rains, and the surface of each becomes spread over with the stones or
pebbles left loose by the process.
Thickness.—-The thickness of the formation, when the river is
large and the valley broad, may be thousands of feet; for, besides
rising above the stream, it underlies its bed, filling the valley, what¬
ever its extent, down to the true Drift, or some other subjacent
formation. If, however, solid rocks form the bed of the river, the
whole thickness is open to view. All the material of the valley-
alluvium belongs properly to the formation of the Champlain epoch,
excepting tho.portion which has been worked over and brought in
by the stream in making the surface of the lower terraces and the
modern river-flats.
Relation to the level of the adjoining river.—There is in all cases some
approximate parallelism between the upper level of the formation
and that of the bed of the adjoining river, although often obscured
by the wear or denudation which has taken place since it was
formed. Yet through long distances there is often a gradual and
regular divergence from this parallelism, in two ways.
(1.) There is usually over the continent a slight increase of
height in going north.
On the coast along the southern borders of New England, as at the mouth of
the Connecticut, or at New Haven, the height of the upper plain above the river
is about 35 feet; at East Hartford, Ct., 30 miles north, 40 feet; at East Wind-
POST-TERTIARY PERIOD.
551
sor, Ct., 48 miles, 71 feet; at Long Meadow and Springfield, Mass., 02 miles,
130 feet; at Willimansett, Mass., 08 miles, 194 feet. (Hitchcock.) At Ilanover,
N.H., the height is about 210V feet. (Hubbard.) Measuring from the lower
river-plain in each case, these heights are—at New Haven, 30 feet; Hartford, 30 ;
E.Windsor, 50; Springfield, 112; Willimansett, 170; Hanover, 182.
The sandy terrace between Schenectady and Albany, N.Y., and opposite the
latter place on the east side of the Hudson, is 330 to 335 feet above the river.
On the Genesee River east of Portage the upper level is 235 feet above the
river.
On the south side of Lake Ontario the " ridge-road" terrace has an elevation
of about 100 feet above the lake, or 590 above tide-level. There are similar
high terraces on Lake Erie and the other lakes west. On the north shore of
Lake Superior the greatest height reported is 330 feet above the lake.
But (2) where a river becomes much diminished in size towards
its source, the height of the upper plain diminishes notwithstanding
the increased northing, on the general principle that all small
streams have small alluvial formations, whether modern or ancient.
Relation to the level of the Ocean.—In the position of the upper limit
of the river-formations there is no direct relation to the level of the
ocean. The beds, although horizontal and undisturbed, occur at
all levels, according to the varying heights of the streams or lakes
over the land. When the latter are two or three thousand feet
above the ocean, the alluvial formation will have the same height,
with the addition of some dozens or scores more of feet, as the case
may be.
In the sea-shore formations, however, there is the same increase
of height above the ocean's level to the northward as there is in the
river-formations above the level of the river's bed. South of New
York the height observed is seldom over 10 or 15 feet; in southern
New England, 30 to 35 feet; on Lake Champlain, 408 feet; at Mon¬
treal, 470 feet above Lake St. Peter, or 450 feet above the river St.
Lawrence at the place. In the Arctic regions, in Barrow's Straits
they have in some places a height of 1000 feet above the sea.
At Brooklyn, Long Island, sea-shore deposits arc 100 feet above the sea; at
New Haven, Ct., 35 feet; at New London, Ct., 35 feet; at Sankaty Head on Nan¬
tucket, 30 feet. In Maine tlicy occur at many places near the coast, as Port¬
land, Cumberland, Brunswick, Thomaston, Cherryfield, Lubec, Perry, etc., at
different elevations, not exceeding 200 feet; also distant from the coast, at Gar¬
diner, Ilallowell, Lewiston, Skowhegan, Clinton Falls, and Bangor. At Lewis-
ton a starfish and various shells were found in a bed 200 feet above the ocean
and 100 above the Androscoggin River; at Skowhegan the beds are 150 feet
above the ocean, and at Bangor 100 feet. (C. II. Hitchcock.)
There are shell-beds at several levels and many localities along the St. Law¬
rence, observed by Logan, and part, as Dawson has shown, are sea-beaches and
others off-shore deposits. At Montreal, at a height of 450, 420, 3C6, 200, 100,
CENOZOIC TIME MAMMALIAN AGE.
above the river, or 20 feet more for each above Lake St. Peter; west of Mon.
treal, near Komptvillc, at a height of 250 feet; in Winchester, 300 ; in Ivenyon,
270 ; in Locliiel, 264 and 290; at Hobbes Falls in Fitzroy, 350; at Dulham Mills,
289; in the counties of Renfrew, Lanark, Carlton, and Leeds, 425; east of Mon¬
treal, near Upton Stati m, 257; farther east, on the river Gouffre, near Mur¬
ray Bay, 130 and 360 feet.
The 100 foot level near Montreal was apparently beneath the sea at the time,
as the shells in which it abounds arc not littoral species, neither are the speci¬
mens water-worn. At Beauport, near Quebec, there are thick beds of this kind,
mostly made of shells, partly littoral, and situated at a height of 200 to 400
feet above the sea. The depth of water inferred for these deep-sea beds by
Dawson from the species of shells is 100 to 300 feet. Dawson makes the marine
formation in Canada to consist (1) of the deep-water clays just mentioned, which
he calls Leda clays, from one of the fossils ; (2) the overlying shallow-water
sands and gravels, called also the Saxicava sand.
The more common shells of the Montreal beds are the following:—Saxicava
rugoHa, Jfya truncata, Tellina Groenlandica, Astarte Laurentiana, Jfytilns ednlis,
31 ya arenaria, Tellina calcarca, Natica clausa, and Lcda Portlandica,—the last
a deep-water species. Among the Beauport species there are the following:—
Natica Groenlandica, N. Heros, Turritella erosa, Scalaria Groenlandica, Lit-
torina palliuta, Cardium Groenlandicum, Cardium Islandicum, Pecten Islandic-uB,
Rliynchonella psittacea, Echinus granulatus. All are cold-water species, and
more like those of the open sea-sliore than the kinds found at Montreal, corre¬
sponding with the fact that Montreal is 150 miles northwest of Beauport (Daw¬
son). The same kinds are common also in the Maine beds. The species thus
far discovered, with perhaps one or two exceptions, are identical with those
now inhabiting the Labrador seas.
The Capclin (a common fish on the Labrador coast) has been found fossil on
the Chaudiere Lake in Canada, 183 feet above Lake St. Peter; on the Mada-
waska, 206 feet; at Fort Colonge Lake, 365 feet.
The facts indicate that salt waters spread over a large coast-region
of Maine, and up the St. Lawrence nearly to Lake Ontario, and
covered also Lake Champlain, besides several Canada lakes. This
great arm of the sea, nearly 500 feet deep at Montreal and in
Lake Champlain, was frequented by whales and seal: remains of
both kinds have been found near Montreal, and a large part of the
skeleton of a whale—Beluga Vermontana Thompson (fig. 840)—has
been dug up on the borders of Lake Champlain, 00 feet above its
level, or 150 above that of the ocean.
II. General Observations.
American Geography.—The close approximation in height be¬
tween the alluvial and sea-shore formations in the same latitudes,
and the parallel increase of height on going north, show that all
belong to a common epoch, and have, in one sense, a common
POST-TERTIARY PERIOD.
553
origin. The facts prove that the continent, over at least its colder
temperate latitudes, was depressed below its present level, and that
this depression extended across it from the Atlantic far towards the
Rocky Mountains, and existed also west of the mountains over
Oregon and California.
The amount of depression was 30 feet along southern New Eng¬
land, as proved by the elevated beaches. It was 30 to 50 in north¬
ern Connecticut, 100 to 170 in Massachusetts, and from 170 to 200 in
New Hampshire, as shown by the height of the upper river terrace
on the Connecticut above the lower flats. It was 400 feet about
Lake Champlain, and 450 or more in the vicinity of Montreal, as
indicated by beds containing marine fossils. The upper terraces of
the Great Lakes show a like depression in their vicinity, amounting
to at least 330 feet on the north shore of Lake Superior. The ele¬
vated sea-beaches of the Arctic correspond to a depression there of
1000 feet in some regions. There was therefore a marked geogra¬
phical change over the northern latitudes between the Glacial and
Champlain epochs,—a change from a condition of elevation, in which
the sea-border lay outside of its present limits, to one of depression, in
which the ocean encroached again on the land, making Lake Cham¬
plain and the St. Lawrence, for a long distance, arms of the sea.
The subsidence may have affected the southern part of the United
States and carried the continent there eight or ten feet below its
present level. The evidence is not satisfactory on this point. On
the Pacific side of the continent the subsidence amounted to some
hundreds of feet. It is probable that the auriferous gravel of
California wras made from the pre-existing rocks and distributed
over the hills and valleys during the Glacial and Champlain epochs.
Sea-beaches mark the presence of the sea in so many places about New Eng¬
land and Canada that we admit at once the conclusion they suggest. And,
being so common to the height mentioned, we certainly have abundant reason
for doubting any depression of the continent bej'ond this extent. Hence, the
submergence in the Glacial period of 4000 or 5000 feet, required to meet the
necessities of the Iceberg theory, may well be pronounced altogether im¬
probable.
Climate.—(1.) Temperature of the sea.—In consequence of the de¬
pression of the continent making an extended gulf of the river St.
Lawrence, the Labrador or polar current (p. 41) would have carried
its waters and temperature westward beyond Montreal. As the
species of shells in the elevated beaches are all such as inhabit the
present coasts from the Arctic to Maine, the temperature of the
waters must have been essentially the same as now. By reference
to the Physiographic Chart, it will be seen that the North Frigid tern-
554
CENOZOIC TIME MAMMALIAN AGE.
perature zone, the coldest of the ocean, descends now on the coast
into the Gulf of St. Lawrence; so that the depression could only
have given greater extension to the waters. The zones of oceanic
temperature in the Middle Post-tertiary period approximated,
therefore, to those of the present day.
(2.) Temperature of the air.—A cold oceanic temperature and a
warm climate may he in close proximity ; the chart referred to
gives an example of this on the coast of Peru (see p. 43). Ilence
we have to look to other facts than those from oceanic species to
determine the climate of the epoch. The depression of the land
over the north would of itself be a cause of a warmer climate than
the present (p. 45) ; and this inference is sustained by the life over
the land. The facts on this point arc stated beyond.
One of the earliest effects of the subsidence would have been the
melting of the glaciers of the Glacial epoch. This would have made
a vast flow of waters over the continent through all the valleys
which had been in process of excavation, and it would have filled
them with sand, gravel, or earth, making each, when the land had
reached its lowest depression, a vast plain of alluvium through
which the stream would have run in its narrow channel, except in
its times of floods, when it may have spread over its whole breadth.
And while the glaciers were disappearing, many a stream or lake
would have existed to stratify the drift (p. 549) and cause denudation
in elevated places where now there are no running waters within
scores of miles.
3. TERRACE EPOCH.
The Terrace epoch belongs in part, at least, to the age of Man,
being, as has been stated on p. 535, a transition epoch. But the
relations, both geographical and zoological, which it bears to the
Post-tertiary are such that its general characteristics are most con¬
veniently stated in this place.
Distribution and origin of the Terraces in North America.
The sea-beaches and river-flats of theChamplain epoch are at the
present time elevated beaches and plains; and the heights of many
of them are already given on pages 549-552. The time when they
were raised, and became terraces along the rivers, lakes, and sea-
coast, corresponds to the Terrace epoch ; and during the process
other parallel terraces were formed. These proofs of elevation are
coextensive with the breadth of the continent, as is evident from
the account of them under the Champlain epoch.
POST-TERTIARY PERIOD.
555
Oscillations of level have taken place in many regions at later
times, and these throw some doubt over the exact amount of
change in particular regions during the Terrace epoch. Yet its
characteristics stand out in bold relief:—
(1.) The continental extent of the area that was elevated.
(2.) The fact that there was an increase in the amount of eleva¬
tion from the south to the north.
The elevated sea-beaches of the Arctic are higher than those of
the St. Lawrence, and those of the St. Lawrence higher than those
of southern New England; and the upper terraces of the Great
Lakes higher than those south of the Ohio. The change of level
was eminently northern, like that introducing the Champlain epoch,
only different in direction,—upward instead of downward.
The formation of the river-terraces (fig. 830, p. 548) has been
stated to be a consequence of the elevation of the land. This is
illustrated in the following cuts. The condition of a river and its
Fig. 831.
Section of a valley in the Champlain epoch, with dotted lines showing the terraces of the
Terrace epoch.
river-flat in the Champlain epoch is shown in fig. 831, in which R is
the river-channel, in the broad river-fiat f f/. Rivers in an open
country have always both these two elements, a channel and a liver-
flat or flood-plain. The stream occupies the former during ordinary
low water, but spreads over the latter during freshets. The sweeping
violence of the flood determines the limits, other things being
equal, and the flat surface of the flood-plain or river-fiat.
If now the interior of a continent be raised, say 100 feet, while
along the sea-coast it is little changed, the river will have an in¬
creased angle of slope, a quicker flow, and greater power of erosion;
and it will gradually wear down its channel, if there are no rocks
to prevent, until the old slope is again attained. The flood-plain
will also sink at the same rate, although with more or less changed
limits, owing to many causes of variation. The line d d/ would then
be the flood-plain or river-flat with its channel (below R). After
another similar elevation, b b' might be the flood-plain and chan¬
nel. In fig. 832 a section of a valley, thus terraced, is represented.
556
CEN0Z01C TIME MAMMALIAN AGE.
(The underlying drift, beneath the alluvium, is not shown.) It
appears thus that each terrace was once part of a flood-plain of the
river.
In the above explanation the terraces are supposed to correspond
each to a separate period of elevation. This may be the case ; and,
when so, the same terrace would be traceable for great distances
along the course of the larger rivers. But successive terraces may
be formed in river-valleys, either (1) during a slowly-progressing
elevation, or (2) in the course of the wear which may be in pro¬
gress between periods of elevation ; and it is often difficult to dis¬
tinguish these accidental or intermediate plains from those that
are distinct records of change of level. One such intermediate ter-
Fig. 832.
Section of a valley with its terraces completed.
race is shown at r in fig. 832. Some of the conditions producing
them are the following:—(1) changes in the river-channel to one
side or the other of the river-valley, altering thereby the action of
the flood-waters during freshets, and causing them to commence
wear according to a new outline ; (2) resistance to wear in a por¬
tion of the alluvium, owing to a degree of consolidation, or to some
obstacle; (3) a permanent diminution in the waters of a stream,
arising from changes about its sources, or in some other way.
It is important to observe also that the same terrace may dif¬
fer in height ten to fifteen feet or more; because (1) the flood-
plains of rivers (the original condition of the terrace-plains) often
differ much in height in different parts ; (2) the rains and stream¬
lets often wear away the soft material of the terraces, diminishing
their height, and sometimes obliterating the plain altogether; (3)
the winds carry off the light soil of the surface, and in the course of
centuries may produce great results.
Again, the terraces of small tributaries at a distance from the
river into which they flow, are lower than those of the latter, be¬
cause both their floods and their eroding power are less.
Again, when there are rocks in the course of a stream, a terrace
above the rocky barrier may differ in height from its counterpart
POST-TERTIARY PERIOD.
557
below, because the stream is unable to wear down its bed, and is
more or less dammed up by the barrier.
The following figures represent terraces on rivers in New Eng¬
land, as figured by Hitchcock, and illustrate both the regularities
and irregularities of level among them. Fig. 833 is from the vi¬
cinity of Hadley, Mass., on the Connecticut; fig. 834 from Hins-
Figs. 833-835.
Sections of terraced valleys in New England, with the heights of the terraces in feet: 833,
on the Connecticut, at Hadley; B, a brook; M, Mill River; H, Hatfield; C, Connecticut
River; II, Hadley; 834, on the Ashuelot, at Hinsdale; 835, on the Connecticut, at Wal-
pole.
dale, N.H., on the Ashuelot River ; fig. 835 from Walpole, N.H., on
the Connecticut. In the last the opposite terraces of 83 and 94 feet
are probably parts of one and the same level; and so also the up¬
permost, 226 and 243. The subordinate terraces are quite nume¬
rous on the left side, arising in part from the fact that two streams,
Cold and Saxon Rivers, enter the Connecticut near by.
Other considerations bearing on this subject, and essential to
right conclusions, are presented in the chapter beyond, on rivers.
General Observations.
Among the results on the American continent of the elevations
of the Terrace epoch were the following; (1) the expansion and
elevation of the land bringing it nearly or quite to its present out-
558
CENOZOIC TIME MAMMALIAN AGE.
line ; (2) the terracing of the borders of the lakes and rivers over
the middle and northern latitudes of the continent; (3) the re¬
ducing of the level of the rivers nearly to that of their present
channels and flood-plains.
ClIAMPLAIN AND TERRACE EPOCHS IN FOREIGN COUNTRIES.
Vast alluvial deposits subsequent in origin to the Drift of the
Glacial period, and river and lake terraces, are as much a general
feature of Britain and Europe as of North America; and, moreover,
the phenomena are most remarkable over the more northern lati¬
tudes. But the fact that glaciers have been perpetual in Europe
since the Glacial period, and the general complexity of geological
movements about that corner of the Orient, make it more difficult
to locate the particular cases in the special epoch to which they
belong, or to separate them from the results of modern changes.
The terraces in Great Britain, and especially its northern part,
Scotland, are on a grand scale. The benches of Glen Roy are an
example of them. The upper terrace is 1139 feet above tide-level;
the second, 1059; the third, 847 feet. This is one among many
cases that might be cited. As a general thing, elevated sea-beaches
occur on the coasts of regions whose interior is diversified with lake
and river terraces. When the facts are thoroughly studied, and the
exceptional cases traced to their true causes, there will probably be
found a system of phenomena which will prove that in Europe, as
in America, the Post-tertiary was a period of high-latitude oscil¬
lations ; of an upward movement for the Glacial epoch; a down¬
ward—to so great a degree that the upper flats in the system were
flooded—for a following epoch, the Champlain ; and an upward
again to the present level in subsequent time.
As an example of the peculiarities of the European continent, it
may be mentioned that the great Swiss glacier which buried all
Switzerland in ice probably belonged to the Terrace epoch ; for the
drift-stones and gravel traced to it overlie the alluvium of the coun¬
try (see p. 577).
LIFE OF THE POST-TERTIARY.
It has been already stated that the plants and invertebrates (Mol-
lusks, etc.) of the Post-tertiary are, with a rare exception, living spe¬
cies, while the Quadrupeds are nearly all extinct.
The Drift epoch in America has afforded no organic relics except
half-fossilized wood. There is as yet no evidence of any quadrupeds
POST-TERTIARY PERIOD.
559
until the milder Champlain epoch had set in. In Europe there is
not this exclusion of organic remains from the Drift.
Europe and Asia.—The Quadrupeds of Post-tertiary Europe are a
great advance beyond those of the Tertiary period in the proportion
and size of the Carnivores. Ca¬
verns in Britain and Europe were
the dens of gigantic Tigers and
Hyenas, while Pachyderms and
Ruminants, equally gigantic com¬
pared with modern species,
roamed over the continent from
the Mediterranean and India to
the Arctic seas. The remains are
found in the earthy or stalag-
mitic floors of caverns; mired in
ancient marshes ; buried in river
and lacustrine alluvium, or sea¬
shore deposits ; or frozen and
cased in Arctic ice.
The most famous of the ca¬
verns are near Kirkdale, Eng¬
land, twenty-five miles north-
northeast of York, explored by
Buckland ; at Bristol, England ;
Kent's Cave near Torquay; Gay-
lenreuth in Germany.
The European caves were
mostly caves of Bears (the great
Ursusspdccus), while those of Eng¬
land were occupied by Hyenas
{Hyaena spelcca), with few bears.
Fig. 830 represents the canine
tooth of the Cave Bear.
At Kirkdale, the Hyena, bones
and teeth—which belonged to at
least seventy-five individuals—
were mingled with remains of
extinct species of Elephant,Tiger,
Rear, Wolf, Fox, Hare, Weasel,
Rhinoceros, Horse, Hippopota¬
mus, Ox, and Deer.—all of which
then populated Britain. The
Hyenas hither dragged the dead carcasses they found, and lived on
Fig. 836.
Tooth of the Cave Bear.
560
CENOZOIC TIME—MAMMALIAN AGE.
the bones, and also the bones of fellow-Hyenas; and the bottom
of the cave was covered with the fragments. Calcareous excre¬
ments were also abundant, quite similar to the excrements of the
modern Hyena of south Africa (II. crocuta).
Some idea has been given of Britain in the age of Reptiles. The following
from Owen gives a later picture of England,—England in the Post-tertiary, the
last age before Man.
" Gigantic Elephants, of nearly twice the bulk of the largest individuals that
now exist in Ceylon and Africa, roamed here in herds, if we may judge from the
abundance of their remains. Two-horned Rhinoceroses of at least two species
forced their way through the ancient forests, or wallowed in the swamps. The
lakes and rivers were tenanted by Hippopotamuses as bulky and with as for¬
midable tusks as those of Africa. Three kinds of wild Oxen, two of which were
of colossal strength, and one of these maned and villous like the Bonassus,
found subsistence in the plains." There were also Deer of gigantic dimen¬
sions, wild Horses and Boars, a Wild-Cat, Lynx, Leopard, a British Tiger larger
than that of Bengal, and another Carnivore, as large, of the genus Macheerodus,
which, "from the great length and sharpness of its sabre-shaped canines, some¬
times eight inches long, was probably the most ferocious and destructive of its
peculiarly carnivorous family." " Besides these," continues Professor Owen,
" troops of Hyenas, larger than the fierce Hysena crocuta of south Africa, which
they most resembled, crunched the bones of the carcasses relinquished by the
nobler beasts of prey, and doubtless often themselves waged a war of extermi¬
nation on the feebler quadrupeds."
There were also in Britain a savage Bear, larger than the Grisly Bear of the
Rocky Mountains, Wolves, and various smaller animals down to Bats, Moles,
Rats, and Mice.
The remains of the Hyeenaspehca have been found in France, Germany, and
Belgium, as well as England. The great Cave Bear (Ursns spelseus) left its
bones in the same countries ; and the cavern at Gaylenreuth is said to have
afforded fragments of at least 800 individuals.
The Elephant of the region was the Elephas primigenius, or Mam¬
moth. It lived in herds over England, and extended its wanderings
across the Siberian plains to the Arctic Ocean and Behrings Straits,
and beyond into North America; but it seems not to have gone far
south of the parallel of 40°. It is stated by Woodward that over 2000
grinders were dredged up by the fishermen of the little village of
Happisburgh in the spac£ of thirteen years; and other localities in
and about England are also noted.
This ancient Elephant was over twice the weight of the largest
modern species, and nearly a third taller. One of the tusks found
measures 12 J feet in length ; it was curved nearly into a circle,
though a little obliquely. Moreover, the body was covered with a
reddish wool and long black hair. The remains are exceedingly
abundant at Eschscholtz Bay, near Behrings Straits, where the ivory
POST-TERTIARY PERIOD.
561
tusks are gathered for exportation. At the mouth of the Lena one
of these animals was found, at the beginning of this century, frozen
and encased in ice. It measured 1G feet 4 inches in length to the
extremity of the tail, and 9 feet 4 inches in height. It retained the
wool on its hide, and was so perfectly preserved that the flesh was
eaten by the dogs.
The Elephant has in all twenty-four teeth (grinders), but usually
only eight at a time, two in each side of each jaw. The new teeth
come up behind and push the others forward and out; and thus
there is a succession until the last has grown.
The Rhinoceros of Post-tertiary Europe is the E. tichorinus. It
spread from England to Siberia. A frozen specimen in Siberia was
found near Wilui in 1772. It had a length of ll j feet, and appears
to have been a hairy species.
The Irish Elk (Megaceros Hibernicus) is another of the gigantic
animals of the Post-tertiary. Specimens have been found in marl
beneath the peat of swamps in Ireland and England, and fragments
in the bone-caverns. The height to the summit of the antlers was
10 to 11 feet, and the span of the antlers was 8 feet, or twice that of
the American Moose.
America.—America in the Post-tertiary period was inferior to
Europe in the number of its Carnivores, but presents the gigantic
feature of the life of the time in its species.
In North America the remains have been found in the ancient»and
surface alluvium, but not yet in the unstratified drift. The species
Fig. 837. Fig. 838.
Elephas Americanus. Mastodon giganteus.
included an Elephant (E. Americanus, fig. 837) as large as the Euro¬
pean; a Mastodon (M. gigantcus, fig. 839) of still greater magni-
37
562
CENOZOIC TIME—MAMMALIAN AGE.
tude ; Horses much larger than the moderns ; species of Ox, Bison,
Tapir, gigantic Beavers, species of Dicotyles (related to the Hog);
also animals of the Sloth tribe, of the genera Megatherium, Mylodon,
and Megalonyx, of great size compared with those now living.
Among Carnivores there were a Bear, a Lion, and a Raccoon; and
these were probably not cavern species, as no bone-caverns of these
animals have been found, although caverns are common in the
country.
The American Elephant ranged from Georgia, Texas, and Mexico
Fig. 839.
Skeleton of Mastodon giganteus (M. Ohioticus).
on the south to Canada on the north, and to Oregon and California
on the west. A tooth was found in ancient alluvium near the Colo¬
rado in 1141-° W. and 35f° N. (Newberry). Parts of one skeleton
were dug up in Vermont at Mount Holly, 1415 feet above tide-level.
The species appears to have been most abundant to the south, in
the Mississippi valley, it preferring a warmer climate than that of
the E. primigenius. Fig. 837 represents one of the teeth found in
the State of Ohio.
POST-TERTIARY PERIOD.
568
The Elephant of northern North America in the British posses¬
sions is supposed to have been the Siberian species.
Mastodon remains are met with most abundantly over the northern
half of the United States, though occurring also in the Carolinas,
Mississippi, Arkansas, and Texas. They are found also in Canada
and Nova Scotia. Five perfect skeletons have been dug up, three
from the fresh-water marshes of Orange eo., N.Y.,—where they ap¬
pear to have been mired,—one from a morass in New Jersey, and
another on the banks of the Missouri. Great numbers of bones
have been found at Big Bone Lick in Kentucky. In New England
a few bones have been found near New Britain and Cheshire in
Connecticut. The finest skeleton in any collection is that set up
by Dr. Warren at Boston; it was obtained from a marsh near New-
burgh. Its height is 11 feet; the length to the base of the tail, 17
feet; the tusks 12 feet long,—2\ feet being inserted in the sockets.
When alive, the height must have been 12 or 13 feet, and the
length, adding 7 feet for the tusks, 24 or 25 feet. Remains of the
undigested food were found between his ribs, showing that he lived
in part on spruce and fir trees. Fig. 839, from Owen's British Mam¬
mals, represents the skeleton of this species in the British Museum.
Castoroides Ohioensis is the name of the great Rodent related to the Beaver
(Castor Canadensis). The Beaver is an animal about three feet long, exclusive
of the tail; and the Cnstoroides was almost or quite five feet. Its bones have
been found in the States of New York, Ohio, Mississippi (near Natchez), etc.
Bison latifrons Leidy, is the name of a Post-tertiary Bison or Buffalo, much
larger than the existing Buffalo, which lived in the Mississippi valley. There
were also species of Ox related to the Musk-Ox, called Bootherium by Leidy.
A stag, Cervus Americanus Leidy, whose bones occur at Natchez, exceeded in
size the Irish Elk. A Horse from the same locality was also gigantic,—a fit
cotemporary, as Leidy observes, of the Mastodon and Elephant.
The American Post-tertiary Lion, Felis atrox Leidy, was about as large as
that of Britain. Only a single jaw-bone has been found at the Natchez bone-
locality, where occur remains of species of Bear, Horse, Elephant, Mastodon,
Castoroides, Megalonyx, and Mylodon.
The animals of the Sloth tribe are South American in type. They
are at the present time mostly confined to South America, as they
were also in the Post-tertiary.
The Cetacean or Whale, whose remains were found on the bor¬
ders of Lake Champlain, is supposed to have been about fourteen
feet in length. Fig. 840 represents the bones of the head, reduced
to one-sixth the natural size. The species, Beluga Vermontana Thomp¬
son, closely resembles the B. Lcucas, or small northern White
Whale.
In South America over one hundred species of extinct Post-tertiary
564
CENOZOIC TIME MAMMALIAN AGE.
quadrupeds have been made out. The bones occur in great num¬
bers over the prairies or pampas of La Plata, and in the caverns of
Brazil; and they include some thirty species of Rodents (Squirrels,
Beavers, etc.), species of Horse, Tapir, Lama, Stag, a Mastodon different
Fig. 840.
Beluga Vermontana (X }/£)■
from the North American, Wolves and half a dozen panther-like
beasts which occupied the caverns of Brazil, Ant-eaters, twelve or
Fig. 841.
Megatherium Cuvieri (X ■h)-
fourteen species related in tribe to the Megatherium (Sloth tribe),
and a dozen or more related to the Armadillo. They number more
POST-TERTIARY PERIOD.
565
species than now exist in that part of the continent, and far larger
species.
The Edentates—including the Sloth, Armadillo, and allied species
—were the most remarkable. The animals of this prder are stupid
in aspect and lazy in movement and attitude.
The Megatherium (fig. 841) exceeded in size the largest Rhinoceros.
The length of a skeleton in the British Museum is 18 feet. Its
massy limbs were more like columns for support than organs of
motion. The femur was three times as thick as an elephant's ; the
massive tibia and fibula were soldered together; the huge tail was
like another hind leg, making a tripod to support the heavy carcass
when it raised and wielded its great arms ; and the hands termi¬
nating the arms were about a yard long, and ended in long claws.
The teeth had a grinding surface of triangular ridges, well fitted
for powerful mastication.
A species of Megatherium has been found in Georgia at Skiddaway
Island, different from that of the Pampas.
Megalonyx is another genus of these large Sloth-like animals.
Remains of species occur over the Pampas to the Straits of Ma-
Fig. 842.
Claw of Megalonyx Jeffersonii.
gellan; but the first species known was found in Virginia, in Green-
Brier co., and named by Jefferson in allusion to its large claws
(fig. 842). Its bones have also been found at Big Bone Lick and
elsewhere.
Mylodon is a third genus, and three species have been described,—two from
South and one from North America. The skeleton of one, M. robustun, is 11 feet
in length; and the animal was therefore much larger than the western Buffalo.
566
CENOZOIC TIME—MAMMALIAN AGE.
The North American, M. Harlani, has been found in Kentucky, in Benton co.,
Mo., and in Oregon.
A fourth allied genus is Scelidotherium, of which seven species have been
made out,—one as large as the Megalonyx, and others but little smaller.
Of the Armadillo (or Dasypus) group the genus Glyptodon (fig. 843)
contained several gigantic species. These animals had a shell
something like a turtle. In the G. clavipes the length of the shell,
measuring along the curve, was five feet, and the total length of the
animal to the extremity of the tail, nine feet. The genus Chlamydo-
therium included other mail-clad species, one of which was as large
as a Rhinoceros ; and the genus Pachytherium, others, of the size of
an Ox.
Such were the characteristic animals of Post-tertiary South Ame¬
rica. The largest Edentates of the existing period are but three
or four feet in length. The Post-tertiary Megatherium probably
exceeded more than one-hundred fold the bulk of any living
Edentate.
Australia.—In Australia the living species are almost exclusively
Marsupials. They were Marsupials also in the Post-tertiary period,
but of different species ; and, as on the other continents, the mo¬
derns are dwarfs by the side of the ancient tribes.
The Post-tertiary Diprotodon was as large as a Hippopotamus, and
somewhat similar in habits. The skull alone is three feet long.
Viewing the globe as a whole, in this Post-tertiary period, we ob¬
serve,—
1. The gigantic size as well as large numbers of the species,—the
Elephants, Lions, Bears, and Hyenas of the Orient far larger than
any modern species; so also the Horse, Elephant, Mastodon, Bea-
Fig. 843.
Glyptodon clavipes (X 3*0)-
POST-TERTIARY PERIOD.
567
vers, and Lion of North America; the Megatheria and other Eden¬
tates of South America; the Diprotodon and other Marsupials in
Australia.
2. The characteristic species of each continent were mainly of
the same type that now characterizes it. Both in the Post-tertiary
period and modern time the Orient is strikingly the continent of
Carnivores; North America, of HeiJbivores; South America, of
Edentates ; Australia, of Marsupials.
With the close of the Post-tertiary far the larger part of these
species became extinct. The destruction did not extend, as has
been before stated, to the Mollusks and other Invertebrates,—for
the same species are all or nearly all now living.
GENERAL OBSERVATIONS ON THE POST-TERTIARY.
Climate.—The hairy covering of the Elephant and Rhinoceros
of Siberia shows that the climate of the Post-tertiary in those
regions was not tropical. Still the several species of British and
European Mammals, of Rhinoceros, Hippopotamus, Elephant, Lion,
Tiger, Hyena, etc., are so closely those of warm climates that it is a
safe conclusion—the only safe one—that Britain and a large part of
Europe were within the warm-temperate zone. It is evident also that
northern Siberia was at least not colder than Lapland, whose annual
mean temperature along its northern limit, according to Dove's
charts, is now 272° F., January mean 5° F., and July mean 50° F.,
while the corresponding quantities for northern Siberia, near the
mouths of the Lena, are at the present time 5° F., —40° F., and 50° F.
The great quantities of Elephant remains at numerous points near
the Arctic Ocean show that the region was the living-place of the
animals, and not one frequented by occasional herds in the very
short Siberian summer. This is further proved by the existence, at
many places in the Arctic, of the remains of forest-trees, buried in
deposits of the Age of the old Elephant. The required climate
would have resulted from the Champlain subsidence (p. 554).
The last or Terrace epoch—in which the continents were raised
nearly to their present level—again cooled down the earth, and
ended in introducing approximately the .existing climates of the
globe; and the extermination of the Cave beasts of Europe and
other Post-tertiary species may have been coincident with this
great climatal change.
Remarks on the Geography of the period are included under the
General Observations on the Cenozoic.
568
CENOZOIC TIME.
GENERAL OBSERVATIONS ON THE CENOZOIC.
1. Time-ratios.—Using the same kind of data as on pp. ,386 and
493 for determining the relative lengths of the ages and periods, we
have for the Tertiary period the maximum thickness of the Eocene
beds of Europe about 3000 feet, part of which is limestone, and for
the Miocene and Pliocene 7000 to 8000 (in the Molasse of Switzer¬
land). It is therefore probable that the Tertiary period was about
half as long as the whole Mesozoic (p. 493).
The data for the Post-tertiary are too uncertain for a satisfactory
estimate. The lapse of time during the period is more marked in
the extent of the valleys made than in the thickness of the rock
deposits. The latter are small, because apparently the earth's sur¬
face was undergoing much smaller oscillations in this last end of
its history than in earlier times. From the extent, of valleys over
the world, both fiords and land gorges, whose excavation was accom¬
plished in the Post-tertiary, it is safe to infer that this period was
at least half as long as the Tertiary.
Adopting these conclusions, the ratios for the Palaeozoic, Meso¬
zoic, and the two periods of the Cenozoic will be 14: 4 : 2: 1. If
D'Orbigny's statements of the thickness of the European Cretaceous
(p. 493) are right, these ratios for the Palaeozoic, Mesozoic, and Ceno¬
zoic are nearly 4:2:1.
2. Geography.—The geographical progress of the Tertiary and
Post-tertiary periods took place in different directions.
A. Tertiary period.—In the Tertiary, there was (1) the finishing of
the rocky substratum of the continents ; (2) the expansion of the
continental areas to their full limits, or their permanent recovery
from the waters of the ocean : (3) the elevation of many of the
great mountains of the globe, or considerable portions of them,
through a large part of their height, as the Alps, Pyrenees, Apen¬
nines, Himalayas, Andes, Rocky Mountains, the loftiest chains
of the globe,—a result not finally completed until the latter part of
the Tertiary.
In North America there occurred a small extension of the con¬
tinent on the Atlantic and Gulf borders ; a vast increase west of
the Mississippi; a small rising of the land on the east and south,
an elevation of 6000 to 7000 feet in the Rocky Mountains (nearly
the whole height of the mass) and 2000 feet or more on the Pacific
border.
The system of progress during the Tertiary was in each respect
a continuation of that which began with the Azoic. In North
America it was enlargement and elevation especially to the south-
GEOGRAPHY.
569
east, south, and southwest, from the original dry land of the Azoic
(p. 130).
The mass of the earth above the ocean's level was increased two
or three fold between the beginning and end of the Tertiary
period.
B. Post-tertiary period.—In the Post-tertiary, the great events, in
America at least, were (1) the excavation of valleys over the lifted
mountains and plains, and the shaping of the lofty summits ; (2) the
distribution of earth and gravel, covering and levelling the rugged
surface of the earth, laying the foundation of prairies, and filling
the broad valleys with alluvium ; (3) the finishing of the valleys
and lake-borders with a series of plains or terraces, and the exten¬
sion of flats along the sea,—a work completed in the age of Man.
The excavation.of valleys by running water began with the first appearance
of dry land, and increased with its extent. But the greatest augmentation
took place after the lofty mountains had risen in the course of the Tertiary
period. The great gorges and canons over a large part of the Rocky Moun¬
tains below a level of 6000 or 7000 feet, and most of the deep channels occupied
by rivers in other regions, then had their beginning.
The canon of the Colorado, between 111° and 115° W., is one of these gorges ;
and though possibly earlier in its commencement than the Tertiary period, it
could have made little progress before the elevation of the mountains after the
Cretaceous; for the present height of the plateau is but 6000 to 7000 feet.
According to Newberry, the canon is 300 miles long, and has walls of rock 3000
to 6000 feet high. These walls are sections of nearly horizontal strata, ranging,
for the principal part of their extent, from the granite to the top of the Carboni¬
ferous, and higher up the stream to the top of the Cretaceous; and the whole
bears undoubted evidence, according to Newberry, that it was made by running
water. The granite has been excavated in some places to a depth of nearly
1000 feet; above this there are 2000 to 2500 feet of Palaeozoic sandstones, shales,
and limestones, 1000 feet of probably Subcarboniferous limestone, and 1200 feet
of Carboniferous sandstones and limestone. A view of one part of the gorge
is given in fig. 940, furnished the author by Newberry; and another of the side
canons, in fig. 941, from the Report of Lieut. Ives, the commander of the Colo¬
rado Exploring Expedition, of which Dr. Newberry was geologist.
There were great oscillations of level in the Post-tertiary as well
as Tertiary; but (1) the Post-tertiary were mainly high-latitude oscil¬
lations, being most prominent over the colder latitudes of the globe,
the cold-temperate and Arctic ; (2) they were movements of the
broad areas of the continents; (3) they brought no mountain-ranges
into existence.
According to the view presented in the preceding pages, there
was an upward oscillation in the Glacial epoch, a downward in the
Champlain epoch, and an upward of moderate extent in the Terrace
epoch. It submerged the region about Montreal and the Ottawa,
570
CENOZOIC TIME.
so that marine shell deposits were there formed,—an event which
had not happened since the Lower Ilelderberg period in the Silu¬
rian age (p. 228).
The course of the movements was, therefore, diverse from that
of earlier time, and their results were also widely different.
A cause of this transfer of the area of oscillation to the high latitudes may be
this : that the accumulation of the successive formations over the temperate and
tropical zones, and the elevation of the lofty mountains of the globe across the
same regions, together with the metamorphism of part of the rocks, had so
weighted, ribbed, and stiffened the crust in these parts that it was less yielding
to any oscillating force than that of the regions more to the north, which till
now had been the comparatively stable area. The series of rocks has less thick¬
ness and completeness in the higher latitudes than in the middle and lower, and
the mountains less height.
During the Post-tertiary some of the most prominent dynami¬
cal agencies on the globe were intensified vastly beyond their former
power:—
(1.) Owing to the completion of the great mountain-chains and
the expansion of the continents, the heights for condensing moist¬
ure and the extent of slope for its accumulation into rivers had
augmented many fold. Moreover, through the union of lands be¬
fore separated by seas into one continental area, the rivers draining
immense regions were for the first time united into a common
trunk. The Post-tertiary was therefore eminently the era of the first-
grand display of completed river-systems,—of the first Amazon, Missis¬
sippi, Ganges, Indus, Nile, etc.
(2.) The elevation of the mountains to snowy altitudes introduced
rivers of ice, or glaciers, among dynamical agencies, or gave them
vastly increased extension.
(3.) The increase of cold, and the existence finally of true frigid
zones, due partly, at least, to an increase of polar lands after the
close of the Cretaceous period and through the Tertiary, added to
the extent of glaciers, rendering them possible in regions where
otherwise they could not have existed.
(4.) The cause last mentioned also gave origin to icebergs.
Great rivers, glaciers, and icebergs were especially characteristic
forces of the Post-tertiary ; and the ice accomplished what was im¬
possible for the ocean. In no other period of geological history
have so large masses of stone been moved over the earth's surface
as in the Glacial and later epochs.
These Post-tertiary agencies were active everywhere over the
continents, putting the finishing-strokes to the nearly completed
globe. There was a development of beauty as well as utility in all
LIFE.
571
these later movements. Those conditions and special surface-de-
tails were developed that were most essential to the pastoral, agri¬
cultural, and intellectual pursuits which were to commence with
the next age.
3. Life.—Grand characteristic of the Cenozoic.—The prominent fact
in the life of Cenozoic time is the expansion and culmination of the
type of Mammals. This culmination took place in the Post-ter¬
tiary period, whose Carnivores, Herbivores, Edentates, and Marsu¬
pials far exceeded in number and size those of the present age. It
was the great feature not of one continent alone, but of all the con¬
tinents, and on each under its own peculiar type of Mammalian
life. The age of Mammals thus stands out prominently among
the ages, strongly marked in its grand distinguishing charap-
teristic.
The Cenozoic was also the time of culmination of the modern
tribe of Sharks or Squalodonts, and of the Crocodiles and Turtles
among Reptiles.
Range of Vertebrate types.—The following table presents to the eye
the range of the more common Vertebrate types through the Me-
sozoic and Cenozoic, showing those which began in the Palseozoic,
those which have their commencement, culmination, and end
within these eras, and those which continue into the age of
Man. The widths of the columns for the several periods cor¬
respond to the time-ratios as deduced on pp. 493, 568. But
they are relatively larger than in the table for the Palaeozoic on
p. 400 (2|ds larger),—the column for the Mesozoic being two-thirds
as wide as that for the Palaeozoic, when the time-ratios deduced
would require it to be one-fourth. This enlargement wras given
the columns to render the details more distinct. The symbol ) (
signifies having biconcave vertebrae. Under Tertiary, the letters
E., M., P., stand for Eocene, Miocene, Pliocene; and P. T. for Post-
tertiary.
While the genera Bos, Bison, and others of the Ox group proba¬
bly commenced in the Pliocene, the Antelope group first appeared
in the early Miocene. Among Carnivores, the Bear family com¬
menced in the earliest Eocene; the Dog family in the middle
Eocene, or Parisian group; the Cat family (Felis, etc.) in the
later Eocene, though possibly in the middle.
In the table the interrogation-mark opposite Herbivores, in the
column of the Jurassic period, is inserted on the authority of Owen,
who questions whether the Stereognathus of the Purbeck beds (p.
462) may not be a "diminutive Ungulate."
572
CENOZOIC TIME.
Fishes.—Tcliosts
Ganoids, Ileterocercal
Homocercal
Selachians
Cestracionts
Ilybodonts.
Squalodonts (Modern Sharks)....
Reptiles
Labyrinthodonts
)( Thecodonts
Enaliosaurs
Pterosaurs
Dinosaurs
Crocodilians.
Gonus Crocodilus
Chelonians, or Turtles
Birds.
Mammals, exclusive of Man
Marsupials
Inscctivorcs
Rodents.
Edentates
Chiropters or Bats
Cetaceans
Herbivores
Perissodaetyl
Artiodactyls
Pachyderms
Proboscidians (Elephant, etc.),
Ruminants, Stag family
Bovine, or Ox family
Carnivores
Quadrumana, or Monkeys
AGE OF MAN.
573
Y. ERA OF MIND.—AGE OF MAN.
In the preceding chapters the progress of the vegetable and ani¬
mal tribes has been followed through the three grand divisions of
geological time,—the Palaeozoic, Mesozoic, and Cenozoic. In the
latter part of the last era the animal kingdom, apart from Man, cul¬
minated ; for the system then reached the highest grade of develop¬
ment presented by the merely animal type, apd brute passion
had its fullest display. In the era now opening, the animal ele¬
ment is no longer dominant, but Mind in the possession of a being
at the head of the kingdoms of life ; and the era bears the impress
of its exalted characteristic even in the smaller size of its beasts of
prey. At the same time, the ennobled animal structure rises to its
highest perfection; for the Vertebrate type, which began during
the Palaeozoic in the prone or horizontal fish, finally becomes erect
in Man, completing, as Agassiz has observed, the possible changes
in the series to its last term.
But, beyond this, in Man the fore-limbs are not organs of loco¬
motion, as they are in all other Mammals: they have passed from
the locomotive to the cephalic series, being made to subserve the pur¬
poses of the head. This transfer is in accordance with a grand law
in nature (explained in the note, $ 5, p. 593) which is at the basis of
grade and development. The intellectual character of Man, some¬
times thought too intangible to be regarded by the zoological
systematist, is thus expressed in his material structure. Man is
therefore not one of the Primates alongside of the Monkeys: he
stands alone,—the Arciion of Mammals (p. 422).
In order to a correct apprehension of the distinctions and emi¬
nence of the era of Mind, a few of the attributes of Man are here
enumerated.
Man was the first being that was not finished on reaching adult
growth, but was provided with powers for indefinite expansion, a
will for a life of work, and boundless aspirations to lead to endless
improvement. lie was the first being capable of an intelligent sur¬
vey of nature and comprehension of her laws; the first capable of
augmenting his strength by bending nature to his service, rendering
thereby a weak body stronger than all possible animal force; the
first capable of deriving happiness from truth and goodness ; of ap
prehending eternal right; of reaching towards a knowledge of self
574
ERA OF MIND.
and of God; the first, therefore, capable of conscious obedience or
disobedience of any moral law, and the first subject to debasement
through his appetites and a moral nature.
There is in Man a spiritual element, in which the brute has no
share. His power of indefinite progress, his thoughts and desires
that look onward even beyond time, his recognition of spiritual
existence and of a Divinity above, all evince a nature that par¬
takes of the infinite and divine. Man is linked to the past through
the system of life, of which he is the last, the completing, crea¬
tion. But, unlike other species of that closing system of the past
(significantly the Zoic era of geological history), he, through his
spiritual nature, is far more intimately connected with the opening
future. ♦
I. Rocks: kinds and distribution.
The following are the formations of the age of Man:—
1. Of mechanical origin.—(a.) Marine.—The extended flats
which border many coasts, as from Long Island to Texas, and be¬
yond, and which are now gradually widening the area of the conti¬
nents ; and deltas, which are similar in general-character, but are
formed about the mouths of rivers.—Sea-beaches.—Sand-drifts or
dunes in the vicinity of the ocean. (b.) Continental.—Alluvium of
the lower river-flats; and, in case a region has undergone elevation
during the age, that at higher levels.—Alluvium along the shores
of lakes; and, where, through the modern opening of barriers or
other cause, the waters have diminished their height, deposits
above the lower plain. About large lakes, different formations
analogous in every respect to the Marine above mentioned, except
in having no marine relics.—Glacier drift or boulders and gravel,
similar to that of the true Glacial epoch, though of more local dis¬
tribution.
2. Of organic origin.—(a.) Marine.—Coral reefs, often of vast ex¬
tent.—Shell deposits. (A) Continental.—Peat beds, or swamp forma¬
tions of vegetable character, consisting largely of growing moss in
temperate and colder climates, and of diminutive turf-making
flowering plants in Alpine and Arctic regions.—Shell beds or shell
marl.—Siliceous infusorial deposits.
3. Of chemical origin.—Calcareous deposits called Travertine, de¬
rived from calcareous waters, in some cases scores of feet in thick¬
ness.—Stalactites and Stalagmites of similar form and origin in
caverns.—Bog deposits of ore called Bog ore.
4. Of igneous origin.—Lavas and tufas of volcanic regions.
AGE OF MAN.
575
The formations here enumerated, whether along lakes, rivers, or
sea-coasts, are usually underlaid by Post-tertiary beds of similar
character, situated at varying depths below, often but a few feet,
sometimes hundreds of feet; and the modern and Post-tertiary de¬
posits are so closely alike that the limits of the two cannot be easily
made out. The difficulty is the greater because the shells of the
Post-tertiary were all of species now living. In many cases deposits
are proved to belong to the age of Man by containing relics of the
peculiar species of the age, as explained beyond.
The agency of air, fresh and marine waters, heat and life, in giving origin to
these deposits, might be here considered. But these topics are discussed under
Dynamical Geology; and to that part of the work the reader is referred.
II. Life.
The approximate number of living species of Plants is 100,000.
The number of species of Animals of the sub-kingdom of Radiates
is about 10,000; of Mollusks, 20,000 ; of Articulates, 300,000; of
Vertebrates, 21,000; making a total in the Animal kingdom of
about 350,000. Of existing Vertebrates the number of species of
Fishes is about 10,000; of Reptiles, 2000 ; of Eirds, 7000; of Mam¬
mals, 2000 = 21,000.
The increase during the Tertiary period in the extent of dry
land and rivers, the height and number of mountains, and the
diversities of the zones* of climate, augmented greatly the variety
of geographical conditions over the globe to which life could
be accommodated. This is especially true of the land; but only
in a limited degree for the ocean, which has smaller extremes of
temperature than the land, and is less affected by its changes of
level.
The terrestrial life of the globe should therefore, on this principle,
have undergone a vast increase in the course of the later Tertiary
and the period of the Post-tertiary, especially in the classes of In¬
sects, Birds, and Mammals, and the tribes of fresh-water Fishes.
Reptiles should have undergone less increase, for the species belong
mainly to the warmer climates, and this type had already culmi¬
nated and was on the decline.
Insects and Birds appear to have reached their times of culmination
in the age of Man, while Mammals, gigantic and ferocious, especially
in their larger species, passed their climax in the period next pre¬
ceding, and disappeared as the age of Man began. Most species of
plants and animals have their parasitic insects; and an augmenta-
576
ERA OF MIND.
tion of the numbers of the former was consequently but providing
for the appearance of the latter.
Invertebrates.—As to the time of the first appearance of existing
Mollusks, it is known only that 15 to 25 per cent, of Miocene species
of marine shells are identical with species now living; 40 to 90 per
cent, of Pliocene; and all of the Post-tertiary species. This does
not necessarily imply that all the species of Mollusks alive now
were alive throughout the Post-tertiary ; for out of the 16,000
living species only a few hundreds have yet been found in the beds
of that period. Future discovery will undoubtedly add much to
the number.
Among Articulates, less than 100 living species from Post-tertiary
deposits are known out of the 300,000 now in existence. The two
tribes latest in appearance among fossil Insects, and rarest even to
the last, are that of the Lepidopters, the tribe of beauty, and that
of the Hymenopters, the tribe of utility, highest instincts, and
superior rank. The species of these tribes are less likely to become
fossilized than those that frequent wet places, where depositions of
silt might be in progress.
Vertebrates.—Very few Fishes, Reptiles, or Birds of the present
era are yet known, from any discovery of fossils, to have existed in
the Post-tertiary. The species have thus far been but little searched
for.
Among Mammals, remains of nearly all the species of modern
Europe have been found in beds containing some of the extinct
Post-tertiary. The number includes the Hare, Rabbit, Beaver,
common Rat and Mouse, the Marten, Wild-Cat, Dog, Fox, Stag,
Roebuck, Reindeer, Aurochs, Hog, Horse, and the Glutton and
Polar Bear of northern latitudes, besides many others; and pro¬
bably all existing species were then distributed much as they are
now over Europe. Moreover, in Sicily and Malta remains of some
African Mammals have been found.
Some of the species may date from the early Post-tertiary; but
the majority apparently from the Terrace or transition epoch.
Their remains are found in caverns and alluvial beds, associated
with bones of the Elephant (E. primigenius), Rhinoceros (H. ticho-
rinus), and Irish Elk (Mcgaceros Hibernicus), and occasionally with
those of the Hyena and Cave Bear. In some cases they have pro¬
bably been mixed by more modern alluvial action ; but in others
they lie as they were originally buried. The alluvial beds in Eng¬
land, France, and Switzerland are more recent than the old Glacial
drift, the latter being observed in several places as an inferior de¬
posit.
AGE OF MAN.
577
It follows, therefore, not only that some of the large Mammals
continued on beyond the time of their meridian nearly or quite
through the Terrace epoch, but also that the modern tribes came
into existence before their extinction. The progressing Terrace
epoch was bringing about the cooler climate required for the mo¬
dern species ; and this change of climate was also causing the dis¬
appearance of the tribes of the older era.
The time of greatest expansion of the Post-tertiary races was probably in the
Champlain epoch, when they would have found the warm climate over the conti¬
nents, which they required (p. 567). Now, the modern species correspond to a
climate like the present, which is a colder one. The Glutton, of Lapland, the
Reindeer, and the Polar Bear were among the earliest of these modern species,
showing that when they began this cooler climate existed. Since the faunas
of the Post-tertiary and age of Man are thus distinct in the climate which they
required, they must have belonged essentially to different epochs,—the modern,
of course, to the later. The Terrace epoch was the one in which the change to
the colder modern climate was in progress, and therefore that which would have
favored the appearance of the modern types and brought about the disappear¬
ance of the more ancient.
The cooler climate might have been begun over Europe and Asia in the early
part of the Terrace epoch, by an increase of Arctic lands, before the terrace
elevations of central Europe had made much progress.
The succession of recent formations in Europe and Switzerland, from the
early Post-tertiary onward, is thus given by Professor Guyot from his own
and other observations :—
1. The northern European and American Glacial drift, the Glacial epoch.
2. The epoch of subsidence, or Champlain epoch, when the large Post-tertiary
fauna was fully developed.
3. The " ancient diluvium" of Switzerland. In some places it is hundreds of
feet thick, and generally stratified; part of it is pebbly, with the rounded stones
sometimes from the size of an egg to that of a man's head, but none of them
are scratched or polished. It covers the plains about Lake Geneva and the low¬
lands of Switzerland, and underlies the moraines of the great Swiss Glacier
(p. 545), and contains, though rarely, bones of the Ursus spelseus, Felix spelrca,
Eleplias primiyeniwS) Rhinoceros tichorinus, Hippopotamux, etc., without any re¬
mains of modern species.
4. The Drift of the great Glacier of Switzerland, together with the Terraces
and Loess or silt of the river-borders. It may belong to the American Terrace
epoch. The true Drift is unstratified, and spreads upward over the hills; the
stones are scratched and polished, and in part lie in distinct moraines, or are mixed
with glacial mud. The alluvium or loess covers this Drift, It is well seen in
the valley of the Rhine north of Basle, where it overlies the continuation of the
old diluvium of Switzerland. It is sometimes one hundred feet thick, and ex¬
tends up several hundred feet above the bottom of the valley. It contains a
vast amount of land-shells, of existing species ; but they have the small size and
aspect that belong to those now found in the Alps 6000 feet above the sea.
Near Geneva, at Matteguin, there is a bone-bed ten to fifteen feet below the
38
578
ERA OF MIND.
surface, which was first explored in 1845 by Pictet. It occurs in gravel whose
stones are scratched as by glacier action, and overlies a clay containing scratched
pebbles, whence, according to A. Favre, it belongs to the epoch of the great
Swiss glacier, or that immediately succeeding it, and not to the "ancient
diluvium" of Switzerland. It contains remains of various Mammals of exist¬
ing species, as the Shrew, Mole, Fox, Rat, Mouse, Hog, Ox, Chamois, Stag, etc.
The loess also contains abundant remains of existing Mammals, together with,
in some cases, the ancient Elephant, and a few other extinct species.
In North America some of the Mammals appear to date from the Terrace
epoch. Among these, according to Holmes and Leidy, there are probably the
modern Horse, or one similar to the common species, the gray Rabbit, and
Tapir; and to these Dr. Holmes adds the Bison, Peccary, Beaver, Musk-Rat,
Elk, Deer, Raccoon, Opossum, Hog, Sheep, Dog, and Ox. The species, how¬
ever, have not in all cases been identified with certainty; and it is not set¬
tled that the commingling of bones is not of more modern origin. In western
Canada, Chapman has found remains of the modern Beaver, Musk-Rat, Elk
(Elaphus Canadensis), and Moose, in stratified gravel which contained also
• bones of the Mammoth and Mastodon.
The caverns of the country have afforded some Mammalian remains, but only
of recent species, though otherwise supposed until recently. In one, near Carlisle
in Pennsylvania, Baird found bones of all the species of Mammals of the State,
besides one or two other species not now Pennsylvanian, but known in regions
not far remote. As a general rule, the bones appeared to indicate that the size
exceeded that of the species at the present time.
A few species of animals have become extinct in recent times,
and partly through the agency of Man. Among these there are
the Moa (Dinornis), and other birds of New Zealand, and the Dodo
and some of its associates of Mauritius and the adjoining islands
in the Indian Ocean. The species are of the half-fledged Ostrich
tribe. Fig. 844 (copied from Strickland's •' Dodo and its Kindred")
is from a painting at Vienna made by Roland Savery in 1628.
The Dodo was a large, clumsy bird, some fifty pounds in weight, with loose,
downy plumage, and wings no more perfect than those of a young chicken. The
Dutch navigators found it in great numbers in the seventeenth century. But
after the possession of the island by the French, in 1712, nothing more is heard
of the Dodo; a head, two feet, and a cranium are all that is left, except some
pictures in the works of the Dutch voyagers.
The Solitaire is another exterminated bird of the same island.
The Moa (Dinornis giganteus) of New Zealand exceeded the Ostrich in size,
being 10 to 12 feet in height. The tibia (drumstick) of the bird was thirty to
thirty-two inches in length, and the eggs so large that it is said " a hat would
make a good egg-cup for them." The bones were found along with charred
wood, showing that they had been killed and eaten by the natives. The name
Dinornis is from kivoq, terrible, and opus, bird.
Besides the Dinornis giganteus, remains of other extinct species of the genus
AGE OF MAN.
Fig. 844.
579
Dodo, with tlio Solitaire in the background.
580
ERA OF MIND.
have been found; also extinct species of Palapteryx and Notornis. Palapterpx
is related to Apteryx; and both Apteryx and Notornis have living species.
On Madagascar another species of this family of gigantic Ostrich-like birds
formerly existed. The species has been called JEpiornis maximus. From the
bones of the leg it is supposed to have been at least twelve feet in height. The
egg was over a foot (thirteen and a half inches) in length.
The great Auk of the North Sea (Alca impennis) is reported to be an extinct
bird by Prof. Steenstrup. The last known to have been seen were two taken
near Iceland in 1844. The bones occur in great numbers on the shores of Ice¬
land, Greenland, and Denmark, showing that it was once a common bird.
A species of Manatee, Rytina Stelleri Cuvier, known in the last century on
the Arctic shores of Siberia, is now supposed to be extinct.
The Aurochs (Bos Bison) of Europe, one of the cotemporaries of the old
Elephant (E. primigenius), would have long since been exterminated from Eu¬
rope but for the protection of Man. Though once abundant, it is now confined
on that continent to the imperial forests of Lithuania, belonging to the Russian
emperor. It is said to exist also in the Caucasus. The Bos primigenius of the
Post-tertiary is supposed to be the same with the Urns (Ure-Ox or Bos Urns)
described by Caesar in his Commentaries, and stated to abound in the Gallic
forests, and is a distinct species from the Aurochs, with which it has been con¬
founded. The species is now quite extinct. It is said to have continued in
Switzerland into the sixteenth century.
The American Buffalo (Bos Americanus) formerly covered the eastern part of
the continent to the Atlantic, and extended south into Florida, Texas, and
Mexico; but now it is never seen east of the Missouri, excepting its northern
portion, and its main range is between the Upper Missouri and the Rocky
Mountains, and from northern Texas and New Mexico to Great Martin Lake in
latitude 64° N. (Baird.)
The spread of the farms and settlements of civilization is gradually limiting,
all over the globe, the range of the wild animals, especially those of large size,
and must end in the extermination of many now existing.
Man.—Some of the fossil relics of Man are skeletons or isolated
bones,—stone arrow-heads and other implements,—pieces of wood,
bone, or stone, hacked or otherwise marked with a tool,—pottery,
—bronze implements,—coins,—engraved tablets of stone,—buried
cities, such as Nineveh and Pompeii.
One of the most perfect of fossil skeletons found in solid rock is
represented in fig. 845. It is from a shell limestone of modern
origin, and now in progress, on the island of Guadaloupe. The spe¬
cimen is in the Museum at Paris. The British Museum contains
another from the same region, but wanting the head, which is in
the collection of the Medical College at Charleston in South Caro¬
lina. They are the remains of Caribs killed in a fight with a neigh¬
boring tribe about two centuries since. In the county of Cork,
Ireland, a skeleton was formerly obtained beneath a bed of peat
eleven feet thick. Fig. 846 represents a ferruginous conglomerate
AGE OF MAN.
581
containing silver coins of the reign of Edward I. and some others,
found at Tutbury, England. It was obtained at a depth of ten
feet below the bed of the river Dove.
The earliest remains of Man and his art occur with the bones of
extinct Post-tertiary animals, in the same conditions as the bones
of the modern Mammals above mentioned. They are flint arrow¬
heads, stone axes, pieces of bone and wood cut or marked, and
Fig. 845. Fig. 846.
lluman skeleton from Guadaloupe. Conglomerate containing coins.
also some of the bones of skeletons. They have been found in
England, France, Switzerland, and some other countries in Europe.
The associated extinct animals include the Elephant (E. primige-
nius), Rhinoceros (R. tichorinus), Irish Elk (Megaceros), and Care
Hyena. The localities are bone-caverns and beds of alluvium. The
facts appear to place it beyond doubt that Man began to exist
before the extinction of the Post-tertiary races, as before stated.
Localities of human relics in stratified deposits.—(1.) Near Abbeville, France, in
the valley of the Somme, at Menchecourt and elsewhere, first investigated by
B. de Perthes.—The excavations occur in a bed of alluvium (stratified loam,
sand, and gravel), situated about ninety feet above the valley ; the layers
apparently had not been disturbed since their formation under the action of
fresh waters. Land-shells (Helix, Pupa, Clausilia) occur in the bed with the
arrow-heads; and bones of the old Elephant were found in the overlying
582
ERA OF MIND.
sandy layer, and a nearly entire skeleton of a Rhinoceros in the inferior bed of
gravel. This evidence of man's antiquity is still questioned.
(2.) Near Amiens, at St. Acheul, and elsewhere in the same valley.—The beds are
similar, and are situated eighty-nine feet above the bottom of the valley. Their
thickness is twenty to thirty feet. The arrow-heads and hatchets are in gravel
resting on chalk; and in the same deposits were found bones of the ancient
Elephant, Rhinoceros, and Hippopotamus. Other localities of flint arrow-heads
occur in the valley of the Seine near Chatillon-sur-Seine, and in that of the Oise,
at Precy.
(3.) At Iloxne, England, five miles east of Diss.—Flint implements occur here
in alluvium with land and fresh-water shells and some Mammalian bones,—part
of them of extinct species; and it is probable that the deposits date back to
the age of the Post-tertiary Mammals. The beds, according to Prestwich, are
more recent than the " boulder-clay" of the Glacial period. The period, he
observes, " was amongst the latest in geological time,—one apparently imme¬
diately anterior to the surface assuming its present form so far as it regards some
of the minor features."
PrestwAh also remarks that "the evidence" from the occurrence of human relics
with the bo.-tes of extinct animals," as it at present stands, does not seem to me
to necessitate 'he carrying of Man back in past time, so much as the bringing
forward of the extinct animals towards our own time; my own previous opinion,
founded on an independent study of the superficial drift or Pleistocene (Post-
tertiary) deposits, having likewise been certainly in favor of this view."
(4.) About several of the Swiss lakes there are the remains of" Lake-habitations,"
in the shape of piles and platforms for their support, which are in view at occa¬
sional low stages of the water. In connection with the structures numerous
human relics have been found, such as stone arrow-heads, lance-heads, axes,
hammers, bone harpoons, bone arrow-heads, pieces of pottery, but nothing made
of metal. According to Keller, 24 of these lake-habitations have been found on
Lake Geneva, 26 on Lake Neufchatel, 16 on Lake Constance, 11 on Lake Bienne,
besides many on the other lakes. Part, however, belong to the later or " Bronze
age."
Rutimeyer states that 66 species of vertebrate animals have been identified in
connection with the earliest ruins,—10 of Fishes, 3 of Reptiles, 17 of Birds, and
the rest (36) Mammals. Eight of the latter were probably domesticated,—the
Docj, P'kj, Horse, Ass, Goat, Sheep, and two species of Oxen; and among the
rest occur bones of the Aurochs and Bison. As these two species were cotem-
poraries of the ancient Elephant, it is possible, as Rutimeyer observes, that the
structures date back to the earliest tribes of Men in Europe. Yet the absence
of the remains of the Elephant and Mastodon seems to show that they belong to
a later date than the deposits of Amiens.
Caverns.—Near Aray, in the Department of Aube, according to De Yibraye,
a human jaw was found in the same bed which contained remains of Rhinoceros
and the Cave Bear and Hyena. In Kent's Cavern near Torquay, England,
there are flint arrow-heads; at Brixham, Devonshire, in the superficial stalag¬
mite; and in one near Liege, explored by Schmerling. Other human relics, as
fragments of rude pottery and bones, have been found with bones of the ancient
Mammals; and they occur in each case in such connections as appear to show
AGE OF MAN.
583
that Man existed before the extermination of the Post-tertiary species. Lartet
has described a cave near Aurignac in the vicinity of the Pyrenees (Department
of Haute-Garonne), which contains human skeletons, and flint and bone or
horn implements, along with fragments of bones or teeth of the Cave Hyena,
Cave Bear, Cave Fclis, Fox, Wild Boar, Bison, Stag, Reindeer, Irish Elk, and
others. The bones are supposed to have been carried in by the human inhabit¬
ants, and the most of them were from their food. Many show that they had
been split open to get out the marrow. Lartet remarks that the people must
have been cotemporaries of the Rhinoceros, Hyena, and Gigantic Elk ; and even
of the Cave Bear, the species among the great Mammals of the Post-tertiary
which was probably the earliest to disappear.
Near Palermo, Sicily, there is a cavern containing human relics, along with
some remains of extinct animals.
In North America there are no known facts sufliciently well authenticated to
be here repeated.
In some of the South American caverns Dr. Lund found human bones along
with those of extinct species, and has published as his conclusion that the bones
belonged to an ancient tribe which was coeval with some of the extinct
Mammals.
As the implements among these early relics are all made of stone,
the age in which they occur has been called the Stone period (or
Stone age), in distinction from the later Bronze or Archaic period,
and still later Iron or Teutonic period. But until Asia has been
fully explored, and found to afford corresponding facts, the term
should be regarded as belonging to European history rather than
to that of the human race; and so also with all conclusions with
regard to the characteristics of the earliest of mankind derived
from the forms of bones or skulls. Geology here passes over the
continuation of the history of Man to Archaeology.
The observations thus far made appear to accord with the view,
already expressed, that in the Terrace epoch there occurred both
the decline of the Post-tertiary races and the introduction of the
modern tribes of Mammals, together with the creation of Man.
Other animal tribes must have been at the same time replenished,
especially those of Birds and Insects, which are terrestrial. Among
fruits and flowers it is not improbable that many kinds were intro¬
duced that added both to the beauty and wealth of the finished
world.
As Man was in the prospect through all the progressing changes
of earlier time, it is not too much to say that in the final fitting up
of the earth with life there was still a reference to him. If creation
was the plan of a being of omniscience and wisdom, the end was in
the beginning, and in each succeeding step.
In order to appreciate the distinctive features of the age of Man,
584
ERA or MIND.
or of an age in any history, it is not right to look to its beginning,
when the past and future are commingled and the progressing
stages are obscured, but onward to a time when the past has faded
and the age stands forth in its own true characters. Thus viewed,
the Cenozoic and present eras stand widely apart. Both are, ap¬
proximately, on the same broad foundation of the lower orders of
life. But, while the former rises to an eminence in the size and
ferocity of its higher brute races, the latter — with more adornment
in its tribes, as we may believe, and less bulk by three-fourths in its
largest animals, as we know,—with an assemblage of life stripped
largely of the animal,—noted neither for Leviathan reptiles, like
the meridian of the Mesozoic era, nor for great beasts of prey, like
the Cenozoic—culminates in Man, with whom all is in harmony.
It has its true affiliation not so much with the past as with the
unending future.
Man of one species.—This oneness of species is sustained by the fol¬
lowing considerations: —
(1.) The fact of an essential identity among men of all races in
physical and mental characteristics.
('2.) The capability of an intermixture of races with continued
fertile progeny. The inferior race in case of mixture with a superior
may dwindle, the people becoming from their position discouraged,
debased, and, in their poverty and superstition, an easy prey to dis¬
ease ; and it may possibly die out, as the weaker weeds disappear
among the strong-growing grass: such decay is hence no evidence
that there is a natural limit to the fertility of " mixed breeds," as
some have urged.
(3.) Among Mammals, the higher genera have few species, and
the highest group next to Man, that of the Ourang-outang, contains
only eight; and these eight belong to two genera,—-Jive of them to
the genus Pithecus, of the East Indies, and three to the higher genus
Troglodytes, of Africa. Analogy requires that Man should here have
pre-eminence. If more than one species be admitted, there is
scarcely a limit to the number that may be made.
The investigations of Darwin on the variations of species, and
other facts of like character, set aside objections to an origin from
one stock arising from the diversities of the races.
These are some of the reasons for believing that Man stands
alone—the one sole species—at the head of the kingdoms of life.
Origin on only one of the two great continents.—Among the higher
Mammals no species is known to have existed originally within the
tropics or temperate zones on both the oriental and occidental con¬
tinents (the former including Europe, Asia, and Africa, the latter,
AGE OF MAN.
585
North and South America); and, more than this, species have a
limited range on that particular continent to which they are
confined.
The same species among the Monkeys—the tribe at the head of
brute Mammals—in no instance occurs on both ; nor even the
same genus ; nor even the same family ; for the American type is
that of the inferior Platyrrhincs, while the African is that of the
Gatarrhines (p. 422), which most approach Man in their features and
structure. This is only the highest of an extensive range of facts
in Zoology sustaining the principle in view. If, therefore, Man is
of one species, he should be restricted also to one continent in his
origin.
Moreover, Man's capability of spreading to all lands, and of
adaptation to all climates, renders creation in different localities
over the globe eminently unnecessary and directly opposed to his
own good. It would be doing for Man what Man could do of him¬
self. It would be contracting the field of conquest before him in
nature, thereby lessening his means and opportunities of develop¬
ment.
Origin on some part of the Oriental continent.—The Orient has always
been the continent of Progi*ess. From the close of the Paleeozoic
its species of animal life have been three times as numerous as those
of North America, and more varied in genera. In the early Ter¬
tiary its flora in the European portion had an Australian type, and
there were Marsupials and Edentates there. In the middle and
later Tertiary it represented recent North America in its flora.
But from this condition it emerged to a higher grade. In the Post-
tertiary it became the land of the Carnivores, while North America
was the continent as distinctively of Herbivores,—an inferior type,
—South America, of Edentates,—still lower,—Australia, of the lowest
of quadrupeds,—the Marsupials. In the closing creations Australia
remained Marsupial, though with dwindled forms ; South America
was still the land of Edentates, but of smaller species, and with in¬
ferior Carnivores and the inferior type of Monkeys or Quadrumana;
North America, of Herbivores, also small compared with the Post-
tertiary ; while the Orient, besides its new Carnivores, received the
highest of the Quadrumana. Thus the Orient had successively
passed through the Australian and American stages, and, leaving
the other continents behind, it stood in the forefront of progress.
It is therefore in accordance with all past analogies that Man should
have originated on some part of the great Orient; and no spot
would seem to have been better fitted for Man's self-distribution
and self-development than southwestern Asia,—the centre from
586
ERA OF MIND.
which the three grand continental divisions of Europe, Asia, and
Africa radiate.
No creations since that of Man.—It is not known that any new spe¬
cies of plants or animals have appeared on the Earth since the
creation of Man.
III. Changes of level on the Earth's surface.
Although the earth, in this its last age, has reached a state of
comparative stability, changes of level in the land still take place.
The movements are of two kinds:—
1. Secular, or movements progressing slowly by the century.
2. Paroxysmal,—taking place suddenly, in connection usually
with earthquakes.
1. Secular.—The secular movements which have been observed
are confined to the middle and higher temperate latitudes, and are
evidently a continuation of the series which characterized the Post-
tertiary period. In this and other dynamical changes the Post-ter¬
tiary and the age of Man have intimate relations. The movements
of the former were directly anticipatory of the latter.
The coast of Sweden and Finland on the Baltic has been proved,
by marks made under the direction of the Swedish government,
to be slowly rising. The change is slight at Stockholm, but in¬
creases northward, and is felt even at the North Cape,—an extent
north and south of one thousand miles. Lyell, in 1834, estimated
the rise at Uddevalla at nearly or quite four feet in a century, and
he made it still greater to the north. The fact of the slow elevation
was first suspected a century and a half since. Here, then, is slow
movement by the century, such as characterized the great changes
of level in past ages.
Beds of recent shells are found along the coast at many places, at
heights from 100 to 700 feet. Part of these may be of Post-tertiary
date. Two miles north of Uddevalla, Lyell found barnacles on the
rocks over 100 feet above the sea; and there are shell-beds at a
height of 400 feet. The former at least belong probably to the pre¬
sent era. Southwest of Stockholm other beds of shells occur, and
the same dwarfish species that now live in the partly-freshened
waters of the Bothnian Gulf.
There are also near Stockholm proofs of a former subsidence
since fishing-huts were built on the coast. A fishing-hut, having a
rude fireplace within, was struck, in digging a canal, at a depth of
sixty feet. It is a common belief that over southern Sweden a
very slow subsidence is now in progress.
AGE OF MAN.
587
In Greenland a slow subsidence is taking place. For 600 miles
from Disco Bay, near 69° N., to the Firth of Igaliko, 60° 43', the
coast has been sinking for four centuries past. Old buildings and
islands have been submerged, and the Moravian settlers have had
to put down new poles for their boats, and the old ones stand, Lyell
observes, " as silent witnesses of the change."
On the North American coast south of Greenland, along the
coasts from Labrador to New Jersey, it is supposed that similar
changes are going on; though more investigation is required to esta¬
blish fully the fact. G. H. Cook concludes from his observations
that a slow subsidence is in progress along the coast of New Jersey,
Long Island, and Martha's Vineyard (Am. Jour. Sci. [2] xxiv.
341); and, according to A. Gesner, the land is rising at St. John's
in New Brunswick; sinking at the island of Grand Manan ; rising
on the coast opposite, at Bathurst; sinking near the Bay of Fundy
and Basin of Mines in Nova Scotia, except, perhaps, on the south
side, and rising at Prince Edward's Island.
The Coral Islands of the Pacific are proofs of a great secular
subsidence in that ocean. The line C C C (Physiographic Chart)
between Pitcairn's Island and the Pelews divides coral islands from
those not coral; over the area north of it to the Hawaian Islands all
the islands are atolls, excepting the Marquesas and three or four
of the Carolines. If then the atolls, as will be shown on a future
page, are registers of subsidence, a vast area has partaken in it,—
measuring 6000 miles in length (a fourth of the earth's circum¬
ference) and 1000 to 2000 in breadth. Just south of the line there
are extensive coral reefs ; north of it the atolls are large, but they
diminish towards the equator and disappear mostly north of it;
and as the smaller atolls indicate the greater amount of subsidence,
and the absence of islands still more, the line A A may be regarded
as the axial line of this great Pacific subsidence. The amount of
this subsidence may be inferred, from the soundings near some of
the islands, to be at least 3000 feet. But as two hundred islands
have disappeared, and it is probable that some among them were
at least as high as the average of existing high islands, the whole
subsidence cannot be less than 6000 feet. It is probable that this
sinking began in the Post-tertiary period.
Since this subsidence ceased—for the wooded condition of the
islands is proof of its having ceased—there have been several cases
of isolated elevations. The following are some of the islands that
have been elevated :—Oahu (Hawaian Islands), 25 feet; Elizabetli
Island, Paumotu Archipelago, 80 feet; Metia or Aurora, 250 feet:
Atiu, Hervey Group, 12 feet; Mangaia, 300 feet; Rurutu, 150 feet;
588
ERA OP MIND.
Eua, Tonga Group, nearly 300; Vavau, 100; Savage Island, 100.
Many others have been raised to a less amount.
2. Paroxysmal.—The changes of level about Pozzuoli near Na¬
ples, at Cutch in the Delta of the Indus, and on the Chilian coast,
South America, are noted examples of modern change of level.
The first appears to have been gradual in its progress; but, if so, it
is not properly secular in the sense in which that term is used.
The cases at Cutch and in Chili were connected with earthquakes;
the other is in the volcanic region of southern Italy.
The temple of Jupiter Serapis at Pozzuoli was originally 134 feet
long by 115 wide, and the roof was supported by forty-six columns
each forty-two feet high and five in diameter. Three of the columns
are now standing: they bear evidence, however, that they were once
for a considerable time submerged to half their height. The
lower twelve feet is smooth ; for nine feet above this they are pene¬
trated by lithodomous or boring shells, and remains of the shells
(a species now living in the Mediterranean) were found in the
holes. The columns when submerged were consequently buried
in the mud of the bottom for twelve feet, and were then in water
nine feet deep. The pavement of the temple is now submerged.
Five feet below it there is a second pavement, proving that these
oscillations had gone on before the temple was deserted by the
Romans. It has been recently stated that for some time previous
to 1845 a slow sinking had been going on, and since then there has
been as gradual a rising.
At the earthquake in 1819 about the Delta of the Indus, an area
of 2000 square miles became an inland sea, and the fort and village
of Sindree sunk till the tops of the houses were just above the
water. Five and a half miles from Sindree, parallel with this
sunken area, a region was elevated ten feet above the delta, fifty
miles long and in some parts ten broad. The natives, with refer¬
ence to its origin, call it Ullah Bund, or Mound of God. In 1838
the fort of Sindree was still half buried in the sea; and during
an earthquake in 1845 the Sindree Lake was turned into a salt
marsh.
In 1822 the coast along by Concepcion and Valparaiso, for 1200
miles, was shaken by an earthquake; and it has been estimated
that the coast at Valparaiso was raised three or four feet. In Feb¬
ruary, 1835, another earthquake was felt from Copiapo to Chili, and
east beyond the Andes to Mendoza. Captain Fitzroy states that
there was an elevation of four or five feet at Talcahuano, which was
reduced by April to two or three feet. The south side of the island
of Santa Maria, near by, was raised eight, feet, and the north ten,
AGE OF MAN.
589
and beds of dead mussels were found on the rocks ten feet above
high-water mark.
Fig. 847.
Temple of Jupiter Serapis.
Thus the earth, although in an important sense finished, is un¬
dergoing changes from paroxysmal movements and prolonged
oscillations. The changes, while more restricted than in the ages
of progress, are yet the same in kind.
590
HISTORICAL GEOLOGY.
GENERAL OBSERVATIONS ON GEOLOGICAL
HISTORY.
1. LENGTH OF GEOLOGICAL TIME.
On former pages (pp. 386, 493, 568) estimates have been given of
the relative lengths of the ages and periods, or their time-ratios.
Future discovery will probably enable the geologist to determine
these ratios with far greater certainty and precision.
Although Geology has no means of substituting positive lengths
of time in place of such ratios, it affords facts sufficient to prove
the general proposition that Time is long; and a few examples are
here given.
Niagara has made its gorge by a slow process of excavation, and
is still prolonging it towards Lake Erie. Near the fall it is 200 to
250 feet deep, and at the fall itself 160 feet,—the lower 80 feet shale,
the upper 80 limestone. The rocks dip 15 feet in a mile up stream,
so that the limestone becomes thicker as it recedes on its course.
The waters wear out the shale, and thus undermine the limestone.
The distance from Niagara to the Queenstown heights which face
the plain bordering Lake Ontario is seven miles.
On both sides of the gorge near the whirlpool (three miles below
the fall), and also at Goat Island, there are beds of recent lake-
shells, Unios, Melanias, and Paludinas, the same kinds that live
in still water near the entrance to the lake, and which are not
found in the rapids. The lake, therefore, spread its still waters,
when these beds were formed, over the gorge above the whirlpool.
A tooth of a Mastodon has been found in the same beds. This
locates the time in the Champlain epoch. Moreover, the waters
would not have been set back to the height of these beds unless
they extended on below for at least six miles from the falls. Six
miles of the gorge have, then, been excavated since that Mastodon
was alive. There are terraces in the shell deposits showing changes
of level in the lakes.
There is a lateral valley leading from the whirlpool through the
Queenstown precipice at a point a few miles west of Lewiston. This
valley is filled with drift of the Glacial epoch, as stated on p. 536;
and this blocking up of the channel may have compelled it to open
a new passage.
If, then, the falls have been receding six miles, and we can ascer-
GEOLOGICAL TIME.
591
tain the probable rate of progress, we may approximate to the
length of time it required. Hall and Lyell estimated the average
rate at one foot a year,—which is certainly large. Mr. Desor con¬
cluded, after his study of the falls, that it was "more nearly three
feet a century than three feet a year." Taking the rate at one
foot a year, the six miles will have required over 31,000 years; if at
one inch a year,—which is 8^ feet a century,—380,000 years. These
calculations may be taken as data for estimating the length of time
required for excavating the great gorge of the Colorado mentioned
on p. 569,—300 miles long and 3000 to 6000 feet deep, some hun¬
dreds of feet of the depth being for much of the distance through
granite. The whole was probably accomplished after the close of
the Mesozoic.
The rate at which coral reefs increase in height affords another
mode of measuring the past. The rate of growth of the common
branching Madrepore is not over one and a half inches a year.
As the branches are open, this would not be equivalent to more
than half an inch in height of solid coral for the whole surface
covered by the Madrepore, and, as they are also porous, to not over
three-eighths of an inch of solid limestone. But a coral plantation
has large bare patches without corals; and the coral sands are
widely distributed by currents, part of them to. depths over one
hundred feet, where there are no living corals; not more than one-
sixth of the surface of a reef-region is in fact covered with growing
species: this reduces the three-eighths to one-sixteenth. Shells and
other organic relics may contribute one-fourth as much as corals.
At the outside, the average upward increase of the whole reef-
ground per year would not exceed one-eighth of an inch.
Now, some reefs are at least 2000 feet thick, which, at one-eighth
of an inch a year, corresponds to 192,000 years. If the progressing
subsidence essential to the increasing thickness were slower than
the most rapid rate at which the upward progress might take place,
the time would be proportionally longer.
The use of these numbers is simply to prove the proposition that
Time is long,—very long,—even when the earth was hastening on
towards its last age. And what, then, of the series of ages that lie
back of this in time ?
In calculations of elapsed time from the thickness of formations, there is
always great uncertainty arising from the dependence of this thickness on a
progressing subsidence. In the case of coral limestone riie data employed give
the least possible time, as is obvious from the above. In estimates made from
alluvial deposits, when the data are based on the thickness of the accumulations
in a given number of years,—say the last 2000 years,—this source of doubt affects
592
HISTORICAL GEOLOGY.
the whole calculation from its foundation, and renders it almost, if not quite,
worthless. An estimate of the length of the Miocene epoch made from data
derived from observations on the deposits then forming in England would have
given no idea of the length of time required for the Miocene molasse of Switzer¬
land; and, in the same manner, any such data from observations at the present
day must be equally fallacious. When the estimate, as from delta deposits, is
based on the amount of detritus discharged by a stream, it is of more value.
But even here there is a source of great doubt, in our ignorance of the oscillations
the continent may have undergone in past time, which, especially if an upward
movement, would have affected the amount of discharge. This source of doubt
alfeets also the calculations from the excavation of valleys.
2. GEOGRAPHICAL PROGRESS IN NORTH AMERICA.
The system of oscillations and progress during the ages to the
close of the Tertiary period, and the new system which succeeded
and characterized subsequent time, have been discussed in the
course of the General Observations on the Azoic, Palaeozoic, Meso-
zoic, and Cenozoic eras; and the reader is here referred to pp. 144,
388, 502, and 508, a recapitulation in this place being unnecessary.
3. PROGRESS OF LIFE.
Several general principles connected with the progress of life
have been illustrated in the course of the preceding history. They
are here brought together and presented briefly and more system¬
atically. The subject may be considered under two heads:—-first,
the system in the progress of life ; second, the relations of the pro¬
gress of life to the physical progress of the globe.
1. System in the Progress of Life.*
1. Reality of the progress.—(1.) In geological history, Mollusks, Co¬
rals, and Crinoids are at one end of the series of animal life, Man
* The following are some of the Criteria of rank among Animals:—
(1.) Under any type, water-species are inferior to land-species : as the Seals to
the terrestrial Carnivores; the water-articulates or Worms and Crustaceans to
land-articulates or Spiders and Insects.
(2.) Species of a tribe bearing some of the characteristics of an inferior tribe or
class are inferior species, and conversely.—Thus, Amphibians show their infe¬
riority to True Reptiles in the young having gills like Fishes; the early Theco¬
dont Reptiles, inferiority to the later in having biconcave vertebra}, like Fishes;
the Marsupials and Edentates, inferiority to other Mammals in having the
sacrum consisting of only two united vertebrae, as in most Reptiles. On the
contrary, the Dinosaurs show their superiority to other Saurians in having the
sacrum made of five (or six) vertebrae, as in the higher Mammals.
PROGRESS OF LIFE.
593
at the other; and if Protophytes or any Algse, and Protozoans, com.
menced in the later part of the Azoic (which is shown to be pro-
(3.) vis a species ill development passes through successive stages of progress,
relative grade in inferior species may often he determined by comparing their struc¬
tures with these embryonic stages.—As a many-jointed larve without any distinc¬
tion of thorax and abdomen is the young state of an Insect, therefore Myriapods
or Centipedes, which have the same general form, are inferior to Insects. As a
young living Gar has a vertebrated caudal lobe (making an accessory upper
lobe to the tail), which it loses on becoming adult, therefore the older Ganoids
with vertebrated tails (or heterocercal) are inferior to the later in which the
tails are not vertebrated (or are homocercal). As the young of a Frog (a tad¬
pole) has the tail and form of a Salamandrian, therefore the Salamandrians are
inferior to Frogs. As the number of segments in the young of Insects often
exceeds much that of the adult, therefore species of adult animals in which there
is an excessive number of segments (beyond the typical number) have in this a
mark of inferiority; and thus the Phyllopods and Trilobites among Crustaceans
bear marks of inferiority, the typical number of segments in the abdomen of a
Crustacean being hut seven, and in the whole body twenty-one,—each pair of mem¬
bers corresponding to one, commencing with the eyes as the anterior.
Professor Agassiz has brought out and illustrated in his writings each of the
above Criteria.
(4.) Species having the largest number of distinct segments in the posterior part
of the body, or having the body ptosteriorly prolonged, are the inferior among those
under any type.—Shrimps and Lobsters are thus inferior to Crabs; Centipedes, to
Insects; Salamandrians, or tailed Batrachians, to the Frogs or tailless Batra-
chians; Snakes, to Lizards; the Ganoids with vertebrated tails, to those with
non-vertebrated. It does not follow on this principle that Frogs, although tail¬
less, are superior to Lizards; for they are of different types of structure.
(5.) Species having the anterior part of the body most compacted or condensed in
arrangement, or having the largest part of the body contributing to the functions of
the head-extremity, are the superior, other things being equal.—Thus, Man stands
at the head of all Vertebrates in having only the posterior limbs required for
locomotion, the anterior having higher uses; and also in having the head most
compacted in structure and brought into the least compass consistent with the
amount of brain. In the same manner, the Carnivores among the large Mam¬
mals (Megasthenes) are superior to the Herbivores, the anterior limbs not having
locomotion as their sole use, and the head being more compacted and con¬
densed for the size of brain. The highest Crabs, the Triangular or Maioids, are
superior in the same manner to the lower, and far more to the Lobster tribe and
other Macrourans ; descending in grade from the higher Crabs, the outer mouth-
organs become more and more separated from the mouth, and finally, in many
Macrourans, they have the form of feet, thus passing from the head-series to the
foot-series. Insects are on this principle superior as a class to Crustaceans,
although of so much less size.
Condensation anteriorly and abbreviation posteriorly is the law of all pro¬
gress in embryonic development, and also of relative rank among species of re¬
lated groups.
39
594
HISTORICAL GEOLOGY.
bable on p. 147), the beginning of the series is even below the types
of Mollusks and Trilobites. (2.) Fishes preceded Reptiles; Rep-
tiles, Mammals; brute Mammals, Man. (3.) Articulates commence
with the inferior marine species, Worms and Crustaceans; they rise
in the Carboniferous age to Insects, the superior class; and later to
the highest Insects, the Hymenopters (the tribe containing the
Bee). (4.) Crustaceans are first represented by Entomostracans, as
Trilobites ; then by the Shrimp and Lobster tribes, in the Carboni¬
ferous and Reptilian ages; then true Crabs, in the later Reptilian
and Mammalian ages ; and finally the highest division of Crabs
(the Maioid, or Triangular), in the age of Man.
2. A type not instituted usually by the introduction of its lowest species, or
developed by the appearance of species in the order of grade.—(1.) Snakes,
while inferior to Turtles, Saurians, and Lacertians, are not known
as fossils until the Tertiary. (2.) Edentates are not known until
after the Pachyderms and Carnivores of the early Tertiary. (3.)
Mosses and Lichens appear long after the great Acrogens of the
Carboniferous Age. (4.) Ganoids and Selachians are not the lowest
of fishes in rank. (5.) Trilobites of the oldest Silurian are not the
lowest of Crustaceans. Barnacles rank much below them, and yet
are not known until the middle of the Reptilian age.
The grand series taken as a whole was an ascending one, but
not by lineal ascent from the lowest to tire highest.
3. The culmination of the various groups of species, or their time of greatest
expansion, not confined to any one period in geological history; but each group
having its own special time, some passing it in the Palaeozoic, others in the
Mesozoic or Cenozoic, and others not having reached it before the age of Man.
—Numerous examples of this general truth are presented in the
tables on pp. 400 and 572, and special examples are also mentioned
on pp. 399 and 496.
The culmination of a type is marked in the culmination or great¬
est expansion of the highest group under the type, and not by that
of all the groups which constitute it. See p. 496 for examples.
The Vegetable and Animal kingdoms have now their periods of culmination.
But, excluding Man, the Animal kingdom passed its climax in the Post-tertiary,
when the Carnivores and Herbivores were largest and most numerous.
Under the Animal kingdom, the sub-kingdom of Mollusks culminated in the
later Mesozoic, when Cephalopods, the highest group, passed their climax; that
of Articulates, in the present era, when Insects are most diversified and most
abundantly represented in the higher groups; that of Vertebrates, exclusive of
Man, in the Post-tertiary, the period being the same as for the Animal kingdom
as a whole, since it is the highest of the subdivisions.
Under Articulates, Insects, Spiders, and also Crustaceans, have their culmina¬
tion in the present era.
PROGRESS OF LIFE.
595
Under Vertebrates, Fishes appear to have culminated in the Tertiary period,
when the highest Sharks existed and were in great numbers; Amphibians, in
the Triassic period; True Reptiles, at the close of the Jurassic or commencement
of the Cretaceous; Birds, in the present era; Mammals, Man excluded, in the
Post-tertiary.
4. The earliest types representing a group often comprehensive types.—
Comprehensive types have been explained to be those which em¬
brace, along with the characteristics of the group to which they
belong, others of another group ; and usually at their first appear¬
ance this other group is not yet in existence. Examples are men¬
tioned on pp. 395, 500.
They are in part intermediate types between two groups, although
never occupying the middle point, as they always belong funda¬
mentally to one of the two. They are often more normal or regular
in structure than later species of the class or group, so far as this is
consistent with the above law,-—the more abnormal or less typical
forms being of later origin. The earliest Mammals included Mar¬
supials, in accordance with the first law,—species which have, along
with the Mammalian structure, some of the characteristics of Birds
and Reptiles, and which were therefore fit inhabitants of the Rep¬
tilian age. With them there appear to have been species of In-
sectivores, one of the more typical groups among the Microstlienes
(p. 423), and none of the inferior abnormal Edentates. In the
Mammalian age the earliest species were certain peculiarly typical
Pachyderms and Carnivores (p. 527). The low Edentates, or Sloth
tribe, appeared at a still later epoch. Two grand facts connected
with comprehensive types are, hence, their partly intermediate posi¬
tion, and their comparatively normal or regular structure.
The idea of comprehensive types was first recognized by Agassiz in the Ganoid
fishes. It was afterwards brought out by Owen in an article on the Labyrin-
thodont Reptiles; and also by Bronn. Agassiz, as stated on p. 203, has called
them synthetic types. Bronn named them complex types (Complications-
Typen), an objectionable name, as they are not complex, but, on the con¬
trary, often in their very nature simpler than the later groups which were
foreshadowed.
5. The earliest types, as shown by Agassiz, sometimes having certain
characteristics which may be styled embryonic, being such as are presented
by embryos or young individuals of the tribe at the present time.
This principle flows out of the general truth that there is a degree
of parallelism between the grades of species in a group and the
successive stages in the embryonic development of an individual
animal in that group. Thus, the early Ganoids had a cartilagi¬
nous vertebral column like the young of modern Gars, and the
596
HISTORICAL GEOLOGV.
central part of the spinal cord (notochord) remains persistent;
they have also a vertebrated tail, like young Gars, as observed by
Agassiz.
6. The species under the early comprehensive types not the lowest species
of the group represented.—This follows from the proposition on p. 583.
7. In the first appearance of a group (as that of Vertebrates, or that of
Reptiles,) the species are often from near the junction of its inferior and supe¬
rior subdivisions,—species from the middle or upper portion of the inferior
either occurring alone, or else associated with others from the middle or lower
portion of the superior. The former frequently pertain to a comprehensive
type, which is intermediate between the two subdivisions, though belonging
usually to the inferior: sometimes there is more than one comprehensive type,
as in the case of land-plants.—This principle is announced and briefly
illustrated on page 396.
A more systematic exhibition of the principle is here given.
The following are the two grand subdivisions in some of the higher groups in
Nature,—the first mentioned being the inferior, the other the superior. The
latter is also the more typical group, or that in which the idea of the type is
more fully represented :—
a. Life in general.—(1.) Vegetable kingdom; (2.) Animal kingdom.
b. Vegetable kingdom.—(1.) Cryptogams, or flowerless plants; (2.) Phasno-
gams, or flowering plants.
c. Animal kingdom.—(1.) The flower-like type, including Radiates; (2.) the
true Animal type, or cephalized species, that is, those having a head (or ante¬
rior and posterior polarity with bilateral symmetry), including Mollusks, Arti¬
culates, and Vertebrates.
d. Sub-kingdom of Mollusks.—(1.) The flower-like type, including the Bryo-
zoans, closely like flowers, the Brachiopods, which also in general were attached
below by stems or pedicels, and Ascidians, also, often attached and many
radiated exteriorly; (2.) the true Molluscan type, including Acephals, Cepha-
lates, and Cephalopods.
e. Sub-kingdom of Vertebrates.—(1.) Water-vertebrates, including Pishes; (2.)
Land-vertebrates, including Reptiles, Birds, and Mammals.
/. Class of Crustaceans.—(1.) Entomostracans; (2.) Malacostracans.
g. Class of Reptiles.—(1.) Amphibians; (2.) True Reptiles (p. 314).
h. Class of Mammals.—(1.) Marsupials, or Semi-oviparans; (2.) Non-marsu¬
pials, or typical Mammals (p. 423).
1. Life in general.—In the inferior subdivision the earliest species of life
were probably the Protophytes,—these and other Algrn commencing in the later
Azoic. They have the locomotive powers of animals, and may therefore be
regarded as an example of one of the comprehensive types, and the first. The
Protozoans (Rhizopods, etc.) may have been the associated species of the superior
group, as remarked on page 147. The two are alike in extreme simplicity of
organization. In Algas the Radiate type of structure, characteristic of the typi¬
cal plant, is not brought out; and in Protozoans neither of the four great
Animal types appears,—the Radiate, Molluscan, Articulate, or Vertebrate.
PROGRESS OF LIFE.
597
If, therefore, these simple species existed in the Azoic era, they were system-
less life, and only foreshadowed the great systems of life which were after¬
wards displayed according to their respective types in the true Zoic ages.
2. Kingdoms.—(a.) Vegetable.—The earliest Land-plants included Acrogens
or the superior Cryptogams, and Conifers or the inferior Phasnogams; and
among them there were the intermediate comprehensive types of Lepidoden-
drids, Calamites, and Sigillarids. See p. 2S3.
(b.) Animal.—Among the earliest of Animals in the Primordial there were the
Cystids (Crinoids). These belong to the Echinoderms, which make the upper por¬
tion of the inferior subdivision of animals; and they are a comprehensive type
between Radiates and Mollusks (the lower portion of the superior subdivision).
Some early kinds have almost the same absence of symmetry in the body that
belongs to Mollusks, and are furnished with only two arms. The associated
superior species were Mollusks and Articulates; and the earliest Mollusks, the
Lingular, and others among Brachiopods, stood on a stem like the Cystids, and
had also two arms.
3. Sub-kingdoms.—(a.) Jfollusks.—The Mollusks of the earliest or Primordial
period were from the higher group of the inferior division, that is, the Brachio¬
pods. The associated superior species comprised Cephalatcs before Acephals,—
that is, the middle before the inferior group.
(6.) Vertebrates.—The earliest Vertebrates were of the inferior subdivision,
or that of Fishes, and from its upper portion,—that is, the orders of Ganoids
and Selachians. The Ganoids were a comprehensive type foreshadowing
the lower group of the superior division of Vertebrates,—that is, Reptiles
(p. 302), which group did not make its appearance until the close of another
age.
4. Classes.—(a.) Gymnosperms in the Vegetable kingdom.—The group of Cy-
cads is one of the most marked of comprehensive types, as explained on
page 418.
(b.) Crustaceans.—The earliest Crustaceans, commencing even in the lowest
Primordial, were Trilobites, ranking with the highest of Entomostracans, or
the inferior subdivision, or even above their true level. They constitute a com¬
prehensive type, foreshadowing the Tetradecapods, which are not known to
have appeared before the Carboniferous age (p. 375). There was also another
comprehensive type in the same early strata,—the Phyllopods, foreshadowing
the still higher division of Decapods, which appeared under the form of Macrou-
rans at the same time.
(c.) Reptiles.—Among the earliest Reptiles in the Carboniferous age there
were the Labyrinthodonts,—the highest of the inferior division, a comprehensive
type having many characteristics of true Reptiles (p. 345). The associated
species were other Amphibians; also species of the lower groups of the
superior division,—that is, the lower Lacertians and Swimming Saurians
(p. 351).
(d.) Mammals.—The earliest Mammals were Marsupials of the inferior sub¬
division, and Insectivores of the superior; and the order of Insectivores is a
typical one among the lower superior. See, further, Appendix H.
598
HISTORICAL GEOLOGY.
8. Comprehensive types generally becoming nearly or quite extinct in the
course of f uture progress.—See page 397 for illustrations.
9. Unity in the successive Floras and Faunas of the ages.—The unity
or harmonious character of the Flora of the Carboniferous age, and
the dependence of this unity on the principle just explained, is the
subject of remark on page 396. It is a marked feature of each of
the ages.
If the view of the Azoic age given on page 596 is right, this unity was
strikingly brought out in the first expression of life. In the Primordial life this
unity is equally marked. There were Brachiopods on stems, associated with the
unsymmetrical Cystids, also on stems, and more flower-like;—and, with these
sedentary species, the Trilobite, nearly as sedentary in habit,—for it seems to
have clung to any supporting surface, like a limpet, though capable of swimming
off or crawling over the sea-bottom. The Gasteropods, Pteropods, and Phyllo-
pods were the more active species. A little later, before the close of the Pri¬
mordial period, there were bivalve Crustaceans in harmony with the bivalve
Brachiopods. There was also a new type, indicating progress, in the large and
active Cephalopods, the Orthocerata, etc.
The same general features continued to characterize the Lower and Upper
Silurian, only with additions to the flower-like animals in Corals, Crinoids,
and Bryozoans, and an increase in the diversity of Brachiopods and Trilo-
bites. The unity also appears in the simplicity of structure of the several types.
In the Mesozoic Fauna there was also a wonderful harmony, as explained
on page 5U1. In the Mesozoic Flora there was a unity as striking as in
the Carboniferous. Conifers, Tree-ferns, and Cycads made up the bulk of
the trees, and the last type, while fundamentally related to the Conifers,
partook somewhat of the character of the Tree-fern in its mode of growth.
At the same time, this comprehensive type had some characteristics of the
palm,—the type it foreshadowed, and which, before the close of the Mesozoic,
was already in the forests along with the highest type of plants, the An-
giosperins.
10. Progress always an unfolding of a type or an exhibition of it in its
■possible diversities, and involving the introduction of inferior as well as supe¬
rior species.—It has been already shown that the progress was not a
lineal upward progress. The facts with regard to comprehensive
types and the associated species throw this principle into a strong
light; for these species occupy nodal points, as they may be called,
or points of divarication, far remote in most cases from the lowest
species of a group.
The progress was not necessarily attended with much rise in
grade. The earliest fishes are of the highest orders in that class.
These orders undergo some little elevation in after-time; but in the
introduction of the Teliosts, or common fishes, in which the great
expansion ultimately takes place, there is a fall below the level of
the early orders.
PROGRESS OF LIFE.
599
Iri all cases, however, there was an unfolding of a type,—an exhi¬
bition of it through the successive appearance of new groups, in which
groups characteristics before only foreshadowed, or existing only in
potentiality, come out into full expression. The early general or com¬
prehensive type thus becomes in a sense specialized, or represented
in numbers of special groups. In the case of Fishes, the type, when
the Teliosts appeared, came forth in its purity, deprived of the
Reptilian features of the Ganoids (marked in their vertebrae, teeth,
air-bladder, and other parts) and developed in those points which
make up the true Fish. Moreover, the Fish-type was at the same
time represented under a diversity of tribes, and an extraordinary
variety of shapes, normal and abnormal, high and low (some almost
of the low grade of a Polyp), which was in great contrast with the
uniformity of structure and limited variation of form in the Ga¬
noids. Nature thus revels in exuberance when displaying a type
after its true level is attained.
In this kind of progress there is naturally expansion towards
inferior as well as superior grades : it is not out of harmony with
the system that Echinoderms should have existed before Polyps,
Tree-ferns and Lepidodendrids before Mosses, Lacertians and
Crocodiles before Snakes, or Herbivores and Carnivores before
Sloths.
When a type had passed its culmination, there was sometimes a
very marked decline in the character of the species that preceded its
final extinction. Examples of this have been referred to in the
last of the Le.ptcence that occurred in the Mesozoic (p. 450), and the
multiplication of uncoiled forms of the Ammonite family which
took place in the Cretaceous (p. 472).
This law of specialization—the general before the special—is the
law of all development. The egg is at first a simple unit; and,
gradually, part after part of the new structure is evolved, that which
is most fundamental appearing earliest, until the being is complete
in all its outer and minor details. The principle is exhibited in the
physical history of the globe,—which was first a featureless globe of
fire, then had its oceans and dry land, in course of time received
mountains and rivers, and finally all those diversities of surface
which now characterize it. Again, the climates began with uni¬
versal tropics ; gradually, zones were apparent; and at last the
diversity of the present day.
But there is a wide distinction in the kind of specialization which
starts from a simple unit like an egg, and that proceeding from com¬
prehensive types among plants and animals. The one is diversity
out of memberless simplicity ; the other, diversity from a unit of
600
HISTORICAL GEOLOGY.
complex structure. The latter is simply an exhibition of the gene¬
ral law of succession in the creations by which the system of life
reached its completion.
2. Relation of the History of Life to the Physical History of the
Globe.
1. The plan of progress was determined with reference to the last age, with
all its diversities of climate, continental surfaces and oceans, as its era of
fullest exhibition.
2. The progress in climate and other conditions involved a concurrent pro¬
gress from the inferior living species to the superior.—The existence of a
long marine era, through the Silurian and part of the Devonian
ages, admitted only of the existence of marine life. Hence the
dominant type of the Silurian was the Molluscan, which, with the
Radiate, is eminently marine. In addition, there were marine Arti¬
culates and marine plants ; and when the Vertebrates began it was
with marine species, the Fishes. Thus the prevalence of waters
involved inferiority of species. The increase of land, gradual purifi¬
cation of the atmosphere, and cooling of the globe, prepared the way
for the higher species.
It is probable that the oceanic waters were also in an impure state
compared with the present, from containing an excess of salts of
lime; and this also involved the existing of inferior species,—such
as Crinoids, Corals, and Mollusks, a very large proportion of whose
weight is in calcareous material. The removal of this excess of
lime from the waters produced limestone strata, purified the
waters, and fitted the oceans for other species.
The great prevalence, in the Primordial, of Lingulae (whose shells eontain a
large amount of phosphate of lime) is further evidence of the greater density
of the waters, and seems to indicate the presence of an excess of phosphates.
3. The progress in climate and in the condition of the atmosphere and waters
involved a localization of tribes in time, or chronographically, just as they are
now localized by climate over the earth's surface, or geographically.—Tribes
were made for a special climate or condition of the globe; and when
this climate or condition had been passed in the earth's progress,
the tribes no longer existed. The culmination of the Reptilian
and Molluscan types in the Reptilian age, or of Trilobites and
Brachiopods in Palaeozoic time, are examples. The former when in¬
stituted had those special relations to climate that made the Repti¬
lian age the era of their culmination ; just as now palms and bananas
reach their perfection only in the equatorial zone; figs in the
PROGRESS OE LIFE-
601
tropical; myrtles and laurels, in the sub-tropical; evergreen trees,
in the warm-temperate; ordinary deciduous trees, in the cold-tem¬
perate ; and pines, in the sub-arctic. As there are now these zones
on going from the equator to the poles, so there were successive eras
passed over from the Silurian—the period of universal warm tempe¬
rature—to the present age of a frigid arctic, and a mean temperature
of 58° to 00° F. Climate may not have been the only cause; but it
was one, and of great importance. The Crustacean type is one of
those which have culminated in the age of Man; and this accords
with the fact that its highest species—the Maioids, or Triangular
Crabs—are now most numerous and of the highest rank in the
colder temperate zone. It was made to reach its maximum in a
cold climate, and therefore in the existing age.
No species survived through all time, and few through two suc¬
cessive periods. The oldest now existing began in the Middle Ter¬
tiary, and these were only Invertebrates. The oldest quadruped
dates no farther back than the Post-tertiary.
But two genera range through the whole series of ages from the
first or Potsdam epoch,—Lingula and Discina,—enough to manifest
the oneness of system from the beginning. There was in general a
changing of genera with the successive periods. Even tribes wholly
disappeared from age to age, as the world outgrew them. Of Trilo-
bites, 500 species once lived, of the Ammonite group, 900 species,
all of which are extinct; the Nautilus tribe, 450 ; three or four spe¬
cies are all that exist. Of Ganoid fishes, 700 species have been dis¬
covered ; the tribe is now nearly extinct. Thus, the old has passed
away as the new has come in. Remains of nearly 40,000 animal
species have been gathered from the rocks, all of which are ex¬
tinct ; and, considering how few of the whole number would have
become fossilized, this can hardly be one-tenth of the number that
have existed and are gone. 2500 extinct species of plants have
been found,—which cannot be over a twentieth of all that have
covered the earth in its former ages.
4. The extermination of species was hi general due to catastrophes, while
the extinction of tribes or higher groups may have been a consequence of secu¬
lar changes in the condition of the climate, atmosphere, or waters.—The ex¬
termination of species here alluded to, and some of the kinds of
catastrophes which .caused them, are briefly considered on p. 398.
5. With regard to the Origination of Species, Geology suggests no
theory of natural forces. It is right for science to search out Na¬
ture's methods, and strive to employ her forces—organic or inor¬
ganic—in the effort, vain though it prove, to derive thence new
living species. The study of fossils has given no aid in this direo
602
HISTORICAL GEOLOGY.
tion. It has brought to light no facts sustaining a theory that
derives species from others, either by a system of evolution, or by a
system of variations of living individuals, and bears strongly against
both hypotheses. There are no lineal series through creation cor¬
responding to such methods of development. Instead of grada¬
tions from Mollusks or Articulates to the lower Fishes, and so on
upward, the Fish-type commences near its summit-level, or rather
between the level of the typical fish and that of a higher class of
Vertebrates. Were either of these plans the system in nature,
examples of the blending of species would be common through all
the classes, high and low; and North America would afford them
as successive stages between the old Elephant or Mastodon and
earlier species, and so throughout the various tribes of life, animal
and vegetable. But, in fact, appearances suggesting the idea of
such shadings among species are exceedingly rare,—wonderfully so,
considering that Paheontology has only the imperfect stony secre¬
tions of animals to study out, which sometimes afford insufficient
distinctions even when perfect and from living species. Under
any scheme of development of species from species, the system of
life, after ages of progress, would have become a blended mass,
—the temple of nature fused over its surface and throughout its
structure. The study of the past has opened to view no such
result.
Geology appears to bring us directly before the Creator; and,
while opening to us the methods through which the forces of na¬
ture have accomplished His purpose,—while proving that there has
been a plan glorious in its scheme and perfect in system, progress¬
ing through unmeasured ages and looking ever towards Man and
a spiritual end,—it leads to no other solution of the great problem
of creation, whether of kinds of matter or of species of life, than
this:—
Deus fecit.
PART IV.
DYNAMICAL GEOLOGY.
Dynamical Geology treats of the causes of events in the earth's
geological progress.
These events include—the formation of all rocks, stratified and
unstratified, with whatever they contain, from the earliest Azoic to
the modern beds of gravel, sand, clays, and lavas ; the oscillations
of the earth's crust; the increase of dry land, elevation of moun¬
tains, and elimination of the surface-features of the globe; the
changes of climate; the changes of life.
The causes or agencies, exclusive of life, that have been engaged
have acted for the most part through the atmosphere, waters, and
rock-material. But they are based necessarily on the general
powers of Nature,—Heat, Light, Electricity, and Attraction. These
fundamental powers have their universal laws,—as the law of
gravitation, according to which falling bodies move; the laws of
chemical attraction, according to which compounds are formed
and decompositions take place ; the laws of cohesion or crystalliza¬
tion, according to which solidification produces crystals, or a crys¬
talline structure ; the laws of heat, as regards conduction, expan¬
sion, etc., and the influence of heat on chemical changes and
growth ; the laws of light, as to its nature, and its action in chemi¬
cal changes and growth, etc. ; the laws of electricity and mag¬
netism: all of which the geologist cannot understand too well.
But the discussion of these topics belongs properly to a treatise on
Physics. The laws of solidification are, however, briefly considered
in this place, on account of their hearing on the structure of rocks.
In addition to the general operation of forces, there are other
actions, that may be embraced under the term climatological, which
proceed from the systematic arrangement and movement of heat,
light, moisture, and electricity about the sphere (causing zones of
temperature, varieties of climate, etc.), and also from the systems
603
604
dynamical geology.
of atmospheric and oceanic circulation. The general facts on these
topics are briefly stated on pp. 39-48, which may well be reviewed
before proceeding with the following pages. In treatises on Physi¬
cal Geography these subjects may be studied to greater length by
the geological student with much advantage.
The subject of dynamics, or the causes or agencies in geological
history, is here treated under the following heads:—
1. Life as an agent in protecting, destroying, and making rocks.
2. Cohesive attraction, with reference especially to crystallization
and the concretionary structure.
3. The Atmosphere, as a mechanical agent.
4. Water, as a mechanical agent.
5. Heat, as an agent in producing volcanic phenomena, non-vol¬
canic igneous eruptions, metamorphism, veins, etc.
6. Movements in the earth's crust, and their consequences,
including the plication of strata, origin of mountains, earthquakes,
and the evolution of the general features of the globe.
7. The chemistry of rocks, or the chemical processes concerned
in their origin and metamorphism, embracing a consideration of
Life, the Atmosphere, Water and Heat as chemical agents. This
department of the science is often called Chemical Geology. As
its proper elucidation would require a large amount of space, and
its study a minute knowledge of the details of Chemistry, the sub¬
ject is not taken up in this Manual.
I. LIFE.
1. Protective Effects.
The protective effects of life come almost solely from vegetation.
1. Turf protects earthy slopes from the wearing action of rills
that would gully out a bare surface ; and even hard rocks receive
protection in the same way.
2. Tufts of grass and other plants over sand-hills, as on sea-shores,
bind down the moving sands.
3. Lines of vegetation along the banks of streams prevent wear
during freshets. When the vegetation consists of shrubs or trees,
the stems and trunks entangle and detain detritus and floating
wood, and serve to increase the height of the margin of the
stream.
4. Vegetation on the borders of a pond or bay serves in a similar
manner as a protection against the feebler wave-action. In many
life.
605
tropical regions, plants growing at the water's edge, like the man¬
grove, drop new roots from the branches into the shallow water,
which act like a thicket of brush-wood to retain the floating leaves,
stems and detritus; and, as the water shallows, other roots are
dropped farther out, which are attended with the same effect; and
thus they keep moving outward, and subserve the double purpose
of protecting and making land.
5. Patches of forest-trees on the declivities in Alpine valleys
serve to turn the course of the descending avalanche, and entangle
snows that, but for the presence of the trees, would only add to its
extent; and in the Alps such groves, wherever existing, are usually
guarded from destruction with great care.
2. Transporting Effects.
1. Seeds are often caught in the hair or fur of animals, and thus
transported from place to place.
2. Seeds are eaten by animals as food, or in connection with their
food, which sometimes pass out undigested, and become planted in
a new region; and, in the case of birds on their migration, they
may be carried far from the place where gathered.
3. Ova of fish, reptiles, and inferior animals are supposed to be
transferred from one region to another by birds and other animals.
Authenticated instances of this are wanting.
4. Snails and fresh-water shells are often floated off on logs or
floating plants, and sometimes are carried into estuaries or the sea,
and so become mingled with marine shells.
0. Migrating tribes of men carry in their grain, or otherwise, the
seeds of various weeds, and also, involuntarily, rats, mice, cock¬
roaches, and smaller vermin. The origin of tribes may often be
inferred from the species of plants and of domesticated and other
animals found to have accompanied them.
3. Destructive Effects.
The destructive effects proceed either from living plants or ani¬
mals, or from the products of decomposition.
1. The roots which come from the sprouting of a seed in the cre¬
vice of a rock, as they increase in size, act like a wedge in tending
to press the rock apart; and, when the roots are of large size,
masses tons in weight may be torn in sunder; and, if on the edge
of a precipice, the detached blocks may be pushed off, to fall to its
base.
606
dynamical geology.
2. Boring animals, like the saxicavous Mollusks, make holes of
the size of the finger, or larger, in limestone and other rocks along
some sea-shores. 8pecies of Saxicava, Pholas, Gastrochcena, and even
some Snails, Barnacles, and Echini, have this power of boring into
stone.
The Teredo, Termites, and many insects, especially in the larval
state, bore into wood.
3. The tunnelling of the earth made by small quadrupeds, as the
mole, sometimes results in the draining of ponds, and the conse¬
quent excavation of gullies or gorges by the outflowing waters.
4. The decay of vegetation about rocks often produces carbonic
acid or different vegetable acids, which become absorbed by the
moisture of the soil, and thus penetrate the crevices of rocks and
promote their decomposition. This is properly one of the chemical
effects of life.
4. Contributions to Rock-Formations.
The capability, on the part of life, of contributing to the material
of rocks depends on several considerations, of which the following
are the more prominent:—
1. The conditions favoring or limiting growth and distribution,—
that is, the laws of geographical distribution of living species.
2. The nature of different organic products, and the fitness of the
species affording them for making fossils or rocks.
After discussing these subjects, some of the methods of contri¬
buting to rock-formations are mentioned under the heads,—
3. Methods of fossilization and concretion.
4. Examples of the formation of strata through the agency of
life.
1. Geographical Distribution.
The subject of the geographical distribution of plants and ani¬
mals, though highly important in this connection, cannot be pro¬
perly treated in a brief chapter; and the student is therefore re¬
ferred to treatises on this branch of science. Its general principles
and bearing are all that can here be explained.
The distribution of terrestrial plants and animals is limited by
different causes.
1. Climate.—The temperature to which each is adapted in its
nature determines, within certain limits, its position in the zones
between the equator and the poles, and also, under any zone,
its special altitude between the level of the sea and the height of
LIFE.
607
perpetual snow. Again, the amount of moisture for which a spe¬
cies is made determines its position in either a moist or an arid
region.
Each continent has its own characteristic climate, arising mainly
out of its special combination of these two elements, temperature
and moisture; and this is one source of the great diversity of life
among the continents. Another point in which the climate of
continents differs is the limit of extreme heat and cold. For ex¬
ample, North America, owing to the extent of its range from the
Arctic circle to the hot tropics, is remarkable for its very wide ex¬
tremes. The severe cold of winter passes over the land to the far
south, destroying whatever cannot stand its power, and the sum¬
mer's intense heat sweeps back again, with a similar effect: so that
the continent cannot grow as many kinds of terrestrial jdants or
animals as that on the opposite side of the Atlantic.
2. Continental idiosyncrasies, or peculiarities that cannot be referred
to climate. Each continent has its characteristic types of plants
and animals. The Marsupials in Australia, and Edentates, or Sloth
tribe, in South America, are examples ; the sedate Platyrrhine Mon¬
keys (p. 422) in South America, and the nimble frolicsome Catar-
rhines in Africa, are others; so also the abundance of Humming¬
birds in the Occident and their absence in the Orient. Examples
might be mentioned indefinitely. Moreover, the range of animal
life, or that of vegetable life, has often a continental feature.
3. Diversities of soil.—Some plants require wet soil, others mode¬
rately dry, others arid; some rich, others sandy, others a surface
of rock ; some the presence of salt or a salt marsh.
The distribution of water-species is determined—First, by the cha¬
racter of the water, whether fresh, brackish, or salt, pure, or impure
from mixed sediment; and but few species adapted for one condi¬
tion survive in the other. Hence, changing a salt lake to a fresh
one, or even making an addition of fresh waters which exceeds
much the amount lost by evaporation (and the reverse), will dwin¬
dle or destroy the living species.
The Aral and Caspian probably made formerly one great salt sea: owing to
the rivers that enter them, the living species are few. The shells are now of but
twelve species, and mainly of the Cardium family, with Mytilus edit/in and a
Dreiexena (Mytilus family); and only two are quoted from the Aral,— Cardium
cdule and Adacna (Cardium) vitrea. The Cardium and Mytilus families are
hence capable of enduring very wide extremes in the saline condition of waters.
It is interesting to note that tne earliest of American bivalves (Acephals) was
of the Cardium family (genus Conocardium), and the Mytilus family was but
little later in introduction.
608
DYNAMICAL GEOLOGY.
Secondly, by temperature and depth of water. The reef-forming
corals grow in the warmer ocean-waters, in which the mean tem¬
perature for the coldest month does not fall below 08° F. The
limit in depth appears to depend on the degree of light and press¬
ure for which the species were made.
The following zones in depth have been recognized by Forbes and other ob¬
servers for the convenience of marking the distribution of marine species:—
1. The Littoral zone,—or the tract between high and low tide level.
2. The Lctminarian zone,—from low water to fifteen fathoms (90 feet). This
zone is so named from the fucoidal sea-weed, called sometimes Tangle-weed,
which is of the genus Laminaria, a plant especially of rocky shores.
3. The Coralline zone,—from 15 to 50 fathoms.
4. The Deep-sea Coral zone,—from 50 to 100 fathoms and beyond.
The zones of oceanic temperature are marked on the Physio¬
graphic Chart, and are explained on pages 42-44, where also facts
are mentioned illustrating the geological bearing of the subject.
2. The nature of different organic products, and the fitness of the species
affording them, for making fossils and rocks.
(a.) Nature of the organic products contributed to rock-formations.—The
following are some of the general facts relating to the nature of the
organic products contributed by life to the rocks:—
1. Plants afford coal, fossil leaves, and fossil wood.
2. Animal remains are more or less durable according to the pro¬
portion of stony ingredients present.
3. Shells, corals,and the like contribute to rock-formations almost
solely carbonate of lime, or the material of limestones.
4. Bones, in addition to carbonate of lime, contain much phos¬
phate of lime and animal matter.
5. Diatoms, Poly cystines, and spicula of Sponges afford silica.
Facts relating to the change of wood to mineral coal are mentioned on page 359.
Mineral oil is another result of the decomposition of vegetation. When the
carbon is only sparingly diffused through earth, it gives it a blackish color,
which is lost when the material is highly heated.
Plants also afford some sulphur, potash, and soda. Carbonic acid is one of
the important results of their decomposition.
Some sea-weeds are calcareous like corals, owing to their secreting lime among
their sparse tissues. (See page 67.)
Animal membranes decompose and pass off for the most part as gases. Some
of the carbon often remains in the bed in which it is buried, giving it a dark
color. Impressions of the soft parts of animals, as of Cephalopods, have been
found in rocks; but they are very rare. The tissues that penetrate shells and
bones are sometimes in part retained by the ancient fossil. Two cases are
LIFE.
609
mentioned by Barrande of the conversion of the animal material within a
Lower Silurian Orthoeeras into adipocere (an animal substance having the ap¬
pearance of spermaceti), and he speaks of them as the oldest mummies ever
exhumed.
A small percentage of phosphates and fluorids is derived from decomposing
animal tissues.
The Excrements of animals afford a considerable amount of phosphates, and,
by decomposition, ammoniacal compounds. The latter are dissipated mostly in
the air, or by solution in waters; while the phosphates are often distributed
through the earth in which the animals live, or else are accumulated in beds, as
in the case of guano. The excrements of the larger animals retain their form,
and constitute the fossils called Coprolitcs. The amount of phosphates from the
life which swarms in some muddy sea-bottoms and shores must be large. For
analyses of Coprolites, see page 67.
Bones are combined with so large an amount of animal gelatine that they are
the food of various animals; and this is a great source of their destruction.
Again, when the animal matter decays, the bones are left very fragile, unless
hardened anew by a substitution of mineral matter. In the Cartilaginous fishes,
the backbone, when it fails wholly of stony material, is not found fossil, as in
most fossil Ganoids.
The teeth of Vertebrates contain much less animal matter than bones, anc1
also a coating of enamel, in which there is considerable phosphate of lime.
They are therefore exceedingly durable, and the most abundant of the remains
of many species. The bony enamelled scales of Ganoid fishes are equally en¬
during, differing much in this respect from the membranous scales of Teliosts.
Of Shells and Corah analyses are given on page 66. As the amount of animal
matter present is usually very small, they have great durability.
A few shells, as those of the Lingulse and Oboli, and probably those also of
Pteropods, contain, like bones, a large amount of phosphate of lime (p. 68).
Traces of phosphates and fluorids are present in both shells and corals.
In a few rare species of Coral of the Gorgonia family, the stony secretions
are siliceous. The Polycystines are siliceous Protozoans.
The siliceous shells of Diatoms and spieula of Sponges have been an import¬
ant source of silica in rocks of all ages (pp. 68, 271, 482, 488). This silica is
usually what is called soluble silica (pp. 55, 488). The index of refraction, as
determined by Rood, from Diatoms is only 1.435, while that of ordinary quartz
is 1.548.
The material of the sponge also is sometimes siliceous, though generally more
like horn in nature. It becomes filled in with mineral matter, and in this state
forms the fossil sponge. A few species of sponge have calcareous spieula.
(£.) The fitness of species for becoming fossilized or concreted
into rocks depends in part on their place and habits of growth.
Water-species of plants and animals are those most likely to be¬
come fossils and contribute to rock-formations ; and next those
that live in marshes, or along shores or the borders of marshes.
The reasons are two:—(1) Because almost all fossiliferous rocks are
of aqueous or marsh origin ; and (2) because organisms buried under
40
610
DYNAMICAL GEOLOGY.
water or in wet deposits are preserved from that complete decom¬
position which many are liable to when exposed on the dry soil, and
are protected also from other sources of destruction. In North
America, during the Cretaceous period, the dry portions of the con¬
tinent east of the Mississippi (see map, p. 489) were, in all proba¬
bility covered with vegetation as densely as now ; and yet we have
no remains of it, excepting the few in the Cretaceous beds of the
Atlantic and Gulf border. We may believe also that there were
numerous Mammals and birds in the forests, for Mammals began in
the Triassic, and birds in the Triassic or Jurassic, hut not the first
specimen has anywhere been found. In the Pliocene Tertiary the
species of plants and birds may have been at least half as numerous
as now. Yet a few hundreds of the former and hardly a score of
the latter are all that have thus far been found fossil. The natural
inference from these facts is that, while we may conclude that we
have a fair representation in known fossils of the marine life of the
globe, we know very little of its terrestrial life,—enough to assure
us of its general character, but not enough for any estimates of the
number of living species over the land.
Plants and all animal matter pass off in gases when exposed in the atmo¬
sphere or in dry earth; and bones and shells become slowly removed in solution
when buried in sands through which waters may percolate. Bones buried in
Wet deposits, especially of clay, are sealed from the atmosphere, and may re¬
main with little change except a more or less complete loss of the animal por¬
tion. Mastodons have been mired in marshes and thus have been preserved to
the present time; while the thousands that died over the dry plains and hills
have left no relics.
Among terrestrial Articulates, the species of insects that frequent marshy re¬
gions, and especially those whose larves live in the water, are the most common
fossils, as the Neuropters; while Spiders, and the insects that live about the
flowers of the land, are of rare occurrence. Waders, among Birds, are more
likely to become buried and preserved than those which frequent dry forests.
But, whatever their habits, birds are among the rarest of fossils, because they
usually die on the land, are sought for as food by numberless other species, and
have slender hollow bones that are easily destroyed.
Vertebrate animals, as fishes, reptiles, etc., which fall to pieces when the animal
portion is removed, require speedy burial after death to escape destruction
from this source as well as from animals that would prey upon them.
Fishes in the ocean, having the means of easy locomotion through the waters,
would be less liable to destruction from changes of level in the land than the
Mollusks of a coast; and hence some of the sharks of the Tertiary continue
through two or three epochs.
The animals generally of the ocean are little liable to extermination from
changes of climate over the land; and hence some marine invertebrate species of
the Miocene Tertiary, many of the Pliocene, and all of the Post-tertiary, con-
LIFE.
611
tinued on into the age of Man, while as regards terrestrial animal life there were
in this interval many successive faunas.
(<?.) The lowest species of life are the best rock-makers, especially Corals,
Crinoids, Mollusks and Rhizopods; for the reason that only the sim¬
plest kinds of life can be mostly of stone and still perform all their
functions. Multiplication of bulk for bulk is more rapid with the
minute and simple species than with the higher kinds; for all ani¬
mals grow principally by the multiplication of cells; and when single
cells or minute groups of them, as in the Rhizopods, are independ¬
ent animals, the increase may still be the same in rate, or even
much more rapid, on account of the simplicity of structure.
3. Methods of Fossilization and Concretion.
In the simplest kind of fossilization there is merely a burial of
the relic in earth or accumulating detritus, where it undergoes no
change. Examples of this kind are not common. Siliceous Dia¬
toms and flint implements are among them.
In general there is a change of some kind ; usually, either a loss
by decomposition of the less enduring part of the organic relic,
with sometimes the forming of new products in the course of the
decomposition, or an alteration through chemical means, changing
the texture of the fossil or petrifying it, as in the turning of wood
into stone.
The change may consist in a fading or blanching of the original colors; in a
partial or complete loss of the decomposable animal portion of the bone or
shell; a similar loss of part of the mineral ingredients by solvent waters, as of
the phosphates and fluorids of a bone or shell ; or a general alteration of the
original organism, leaving behind only one or two ingredients of the whole; or
a combining of the old elements into new compounds, as when a plant decays and
changes to coal and bitumen, a resin to amber, animal matter to adipocere.
The change may be merely one of crystallization. The carbonate of lime of
shells is often partly in the state of aragonite; and when so, there is usually a
change in which the whole becomes common or rhombohedral carbonate of lime
(calcite). Sometimes the compact condition of the original fossil is altered to
one with the perfect cleavage of calcite, as often happens in encrinal columns
and the spines of Echinoids.
The change often consists in the reception of new mineral matter into the
pores or cellules of the fossil, as when bones are penetrated by limestone oroxyd
of iron.
The change is frequently a true petrifaction, in which there is a substitution
of new mineral material for the original; as when a shell, coral or wood is
changed to a siliceous fossil through a process in which the organism was sub¬
jected to the action of waters containing silica in solution. In other cases, the
organism becomes changed to carbonate of lime, as in much petrified wood;
612
DYNAMICAL GEOLOGY.
and in others, to oxyd of iron and pyrites; and more rarely to fluor spar, heavy
spar, or phosphate of lime.
The remains of organisms have very frequently been ground up
by the action of. waves or by currents of water, and thus reduced
to a calcareous earth,—the concretion of which has made lime¬
stones.
When the fossils are minute," like Rhizopods and Diatoms, the
simple concretion of the shells will make a solid rock, as in the
case of chalk and flint (p. 488).
Ehrenberg estimates that about 18,000 cubic feet of siliceous organisms annu¬
ally form in the harbor of Wismar in the Baltic; and he has also found that
similar accumulations are going on in the mud of American and other harbors.
The bed of fihizojiods accumulating in the North Atlantic, mentioned on page
488, contains, according to Huxley, about 85 per cent, of these calcareous shells,
mostly of the genus Globigerina, besides some siliceous Diatoms: it has probably
a breadth (between Ireland and Newfoundland) of 1300 miles; and, as a similar
bottom was found by Captain Dayman near the Azores, the bed has been sup¬
posed to extend southward at least 600 miles. Ehrenberg found, in a specimen
examined by him, 85 species of calcareous Rhizopods, 16 of Polycystines, and
17 of Diatoms, with only a few arenaceous grains not of organic origin.
Off the Atlantic coast, from Florida north, between depths of 90 and 1500
feet, the bottom consists half or more of Rhizopod shells ; and at greater depths,
even beneath the Gulf Stream, to 6000 feet (as observed in lat. 28° 24', long.
79° 13'), almost solely of them. (Pourtales.)
The siliceous shells of the microscopic Polycystines have been found not only
in the frigid Sea of Kamtchatka (p. 488; see Amer. Jour. Sci. [2] "xxii. pi. 1,
for figures) and the North Atlantic, but also in the South Pacific, on both coasts
of the Atlantic, in the Mediterranean, and, within the tropics, at Barbadoes in
the West Indies and the Nicobar Islands in the East Indies. Ehrenberg has
named 282 species from a marl-like deposit at Barbadoes, considered as Ter¬
tiary, and 100 species from the Nicobar Islands, part of them identical with those
of Barbadoes.
But when the fossils are comparatively large, as with ordinary
corals and shells, the intervals between them must be filled with
earth of some kind, derived from the wearing action of the waters.
It may be the mud or detritus from rivers or from wave-action along
sea-shores. But when calcareous, it has evidently come from the
wear of the shells, corals, or crinoids themselves ; and hence any
limestone rock made up of shells, corals, or crinoids which has the
interstices thus filled in with limestone bears conclusive evidence
in itself that it has not been formed in the deep ocean, but within
the reach of current or wave action. Rhizopods make the only
solid deep-water limestones.
The kinds of limestone made through the agency of life include
soft marl or calcareous earth, chalk, compact limestone, sometimes
PEAT.
613
oolitic, of white, gray, bluish, blackish and other colors,—the dark
colors mostly due to the presence of carbon from animal or vegetable
decomposition.
The origin of strata through organic growth or accumulation is
well illustrated in the history of peat beds and coral reefs ; and
this subject of life is therefore concluded by a brief description
of their modes of formation.
1. Peat Formations.
Peat is an accumulation of half-decomposed vegetable matter
formed in wet or swampy places. In temperate climates it is due
mainly to the growth of mosses of the genus Sphagnum. This
plant forms a loose turf, and has the property of dying at the extre¬
mity of the roots as it increases above ; and it thus may gradually
form a bed of great thickness. The roots and leaves of other plants,
or their branches and stumps, and any other vegetation present, may
contribute to the accumulating bed. The carcasses and excrements
of dead animals at times become included. Dust may also be
blown over the marsh by the winds.
In wet parts of Alpine regions there are various flowering plants
which grow in the form of a close turf, and give rise to beds of peat
like the moss. In Fuegia, although not south of the parallel of 56°,
there are large marshes of such Alpine plants, the mean tempera¬
ture being about 40° F.
The dead and wet vegetable mass slowly undergoes a change,
becoming an imperfect coal, of a brownish-black color, loose in tex¬
ture, and often friable, although commonly penetrated with root¬
lets. In the change the woody fibre loses a part of its gases; but,
unlike coal, it still contains usually 25 to 33 per cent, of oxygen.
Occasionally it is nearly a true coal.
An analysis afforded—Carbon, 5S.09, hydrogen, 5.93, oxygen, 31.37, ashes,
4.61 = 100. But there are several substances present, including three or four
distinct resins and vegetable principles. It affords a number of important pro¬
ducts by distillation, among them Paraffine. Traces of phosphates are present,
arising from animal decompositions.
Peat-beds cover large surfaces of some countries, and occasionally
have a thickness of forty feet. One-tenth of Ireland is covered by
them ; and one of the " mosses" of the Shannon is stated to be fifty
miles long and two or three broad. A marsh near the mouth of the
Loire is described by Blavier as more than fifty leagues in circum-
614
DYNAMICAL GEOLOGY.
ference. Over many parts of New England and other portions of
North America there are extensive beds. The amount in Massa¬
chusetts alone has been estimated to exceed 120,000,000 of cords.
Many of the marshes were originally ponds or shallow lakes, and
gradually became swamps as the water, from some cause, diminished
in depth. The peat is often underlaid by a bed of whitish shell
marl, consisting of fresh-water shells—mostly species of Cyclas and
Planorbis—which were living in the lake. There are often also
beds of the siliceous shields of Diatoms.
Peat is used for fuel and also as a fertilizer. When prepared for burning, it is
cut into large blocks and dried in the sun. It is sometimes pressed in order
to serve as fuel for steam-engines. Muck is another name of peat, and is used
especially when the material is employed as a manure. It includes also impure
varieties not fit for burning, being applied to any black swamp-earth consisting
largely of decomposed vegetable matter.
Peat-beds sometimes contain standing trees, and entire skeletons
of animals that had sunk in the swamp. The peat-waters have
often an antiseptic power, and flesh is sometimes changed by the
burial into adipocere.
2. Coral Formations.
Coral formations are made through the growth mainly of coral
zoophytes, and are confined to the warmer latitudes of the globe.
Kinds—Coral formations, while of one general mode of origin, arc
of two kinds:—
1. Coral islands.—Isolated coral formations in the open sea.
2. Coral reefs.—Banks of coral bordering other lands or islands.
Distribution.—The limiting temperature of reef-forming corals is
about G8° F.; that is, they do not flourish where the mean tempera¬
ture of any month of the year is below 68°. The extent of the Coral
seas is shown by the position of the north and south lines of 08° F.
on the Physiographic Chart, as already pointed out.
The exclusion of corals from certain tropical coasts is owing to dif¬
ferent causes.—(1.) The cold extratropical oceanic currents, as in the
case of western South America (see map). (2.) Muddy or alluvial
shores or the emptying of large rivers; for coral-polyps require
clear sea-water, and generally a solid foundation to build upon.
(3.) The presence of volcanic action, which, through occasional sub¬
marine action, destroys the life of a coast. (4.) The depth of water
on precipitous shores; for the reef-corals do not grow where the
depth exceeds 100 feet.
CORAL FORMATIONS.
615
For the last-mentioned reason, reefs are prevented from com¬
mencing to form in the deep ocean. The notion that coral islands
are rising from its depths has no support in facts: they must have
the land within a few fathoms of the surface to begin upon.
Coral formations are most abundant in the tropical Pacific, where there are 290
coral islands, besides extensive reefs around other islands. The Paumotu Archi¬
pelago, east of Tahiti, contains between seventy and eighty coral islands; the
Carolines, including the Radack, Ralick, and Kingsmill groups, as many
more; and others are distributed over the intermediate region. The Tahitian,
Samoan, and Feejee Islands are famous for their reefs; also New Caledonia and
islands northwest. There are reefs also about some of the Hawaian Islands.
The Laccadives and Maldives in the Indian Ocean are among the largest coral
islands in the world. The East Indies, the eastern coast of Africa, the West
Indies and southern Florida abound in reefs; and Bermuda, in latitude o2° N.,
is a coral group. Reefs are absent from western America, except along by Pa
nama, and mostly from western Africa, on account of the cold extratropical
currents that flow towards the equator: for the same reason, there are no reefs
on the coast of China. (See the Physiographic Chart.)
1. Coral Islands.
Forms.—Atolls.—The larger part of coral islands consist of a nar¬
row rim of reef surrounding a lagoon, as illustrated in the annexed
sketch (fig. 848). Such islands are called atolls,—a name of Mal-
dive origin. Maps of two atolls are shown in figs. 849, 850, showing
the rim of coral reef, the salt-water lake or lagoon, and the varia-
Fig. 848.
Coral island, or atoll.
tions of form in these islands: they are never circular. The size
varies from a length of fifty miles to two or three, and when quite
small the lagoon is wanting, or is represented only by a dry de¬
pression.
The reef is usually to a large extent bare coral rock, swept by the
waves at high tide. In some, the dry land is confined to a few iso¬
lated points, as MenchikofF Island, of the Caroline group (fig. 850);
in others, one side is wooded continuously, or nearly so, while the
other is mostly bare, or is a string of green islets, as in fig. 849,
representing Apia, one of the Kingsmill Islands. The higher or
616
DYNAMICAL GEOLOGY.
wooded side is-that to the windward, unless it happens to be under
the lee of another island. On the leeward side there are often chan-
Fig. 849. Fig. 850.
W-
SBSSsarfftf
Jt I JCas
t- &... Mif
'W
„„ #
I
Atolls.—Fig. 849, Apia, oue of the Kingsniill Islands; 850, Menchikoff, one of the
Carolines.
nels opening through to the lagoon (e, fig. 849), which, when deep
enough for shipping, make the atoll a harbor; and some of these
coral-girt harbors in mid-ocean are large enough to hold all the
fleets of the world.
Fig. 851 represents a section of an island, from the ocean (o)
to the lagoon (£). On the ocean side, from o to a there is shallow
water for some distance out (it may be a quarter or half a mile or
more); and, where not too deep (not over one hundred feet), the
bottom is covered here and there with growing corals, a to b is a
platform of solid coral rock, mostly bare at low tide, but covered
Fig. 851.
Section of a coral island, from the ocean (o) to the lagoon (/).
at high, and having a width usually of about a hundred yards:
there are shallow pools in many parts of it, abounding in living
corals of various hues, Actinite (Sea-anemones), Star-fishes, Sponges,
Shells, Shrimps, and other kinds of tropical life, and towards
the outer margin it is quite cavernous, and the holes are fre¬
quented by crabs, fishes, etc. At b is the white beach,six or eight
feet high, made of coral sand or pebbles and worn shells; b to d is
the wooded portion of the island. The whole width from the beach
(b) to the lagoon (c) is commonly not over three or four hundred
CORAL FORMATIONS.
617
rods. At c is the beacli on the lagoon side, and the commence¬
ment of the lagoon. Corals grow over portions of the lagoon,—
although in general a large part of the bottom, both of the lagoon
and the sea outside, is of coral sand.
Beyond a depth of 100 feet there are no growing corals, except
some kinds that enter but sparingly into the structure of reefs,
the largest of which are the DcndrophyUicc.
Coral recf-rock.—The rock forming the coral platform and other
parts of the solid reef is a white limestone made out of corals and
shells. Its composition is like that of ordinary limestones.
In some parts it contains the corals imbedded, but in others it is
perfectly compact, without a fossil of any kind, unless an occasional
shell. In no case is it chalk. The compact non-fossiliferous kinds
are formed in the lagoons or sheltered channels ; the kinds made
of broken corals, on the sea-shore side, in the face of the waves ;
those made of corals standing as they grew, in sheltered waters
where the sea has free access.
The following are the principal kinds of coral rocks:—
1. A fine-grained, compact, and clinking limestone, as solid and flint-like in
fracture as any Silurian limestone, and with rarely a shell or fragment of coral.
This variety is very common: and. where coral reefs or islands have been ele¬
vated, it often makes up the mass of the rock exposed to view. The absence of
fossils, while the rock was evidently made out of corals and shells, is a remark¬
able and instructive fact.
2. A compact oolite, consisting of rounded concretionary grains, and gene¬
rally without any distinct fossils.
3. A rock equally compact and hard with No. 1, but containing imbedded
fragments of corals, and some shells.
4. A conglomerate of broken corals and shells, with little else,—very firm
and solid ; many of the corals several cubic feet in size.
5. A rock consisting of corals standing as they grew, with the interstices
filled in with coral sand, shells, and fragments. In general the rock is exceed¬
ingly solid; but in some cases the interstices are but loosely filled.
Coral beach-rock.—The beach-rock is made from the loose coral
sands of the shores which are thrown up by the waves and winds.
The sands become cemented into a porous sandstone, or, where
pebbly, into a coral pudding-stone. It forms layers, or a laminated
bed, along the beach of the lagoon, and also on the sea-sliore side,
sloping sometimes at an angle of five or six degrees towards the
water.
Formation of the coral structure.—A reef region is a plantation of
living corals, in which various species are growing together,—at
one place in crowded thickets, at another in scattered clumps over
fields of coral sand. There is the same kind of diversity that exists
618
DYNAMICAL GEOLOGY.
in the distribution of vegetation over the land. Some of the kinds
branch like trees of small size or shrubs (Madrepora) ; others form
closely-branched tufts (Pocilloporcc, many Pontes) ; others resemble
clustered leaves (Merulince, Manoporcc), or tufts of pinks (Tubiporcc),
or lichens and fungi (Agaricix, etc.) ; others grow in hemispherical
or subglobular forms [Astrece, Meandrincc, and some Pontes); and
others are groups of slender, brilliantly-colored twigs (Gorgonicc).
When alive in the water, all these corals are covered throughout
with expanded polyps, emulating in beauty of form and colors the
flowers of the land.
The most common groups of reef-forming corals are the Madrepora, Pocillo-
pora, Porites, Astrea, Meandrina, and Millepora.
1. Madrepora.—Corals usually neatly branched; branches with pointed ex¬
tremities, each ending in a small cell or calicle; surface covered with calicles (or
prominent polyp-cells) about a line in diameter.
2. PocillojMra.— Corals closely branched, with uniform width of interval
between: branches blunt at the extremity; surface covered with angular
prominences, a line or two thick, each containing several polyp-cells; spaces
between the prominences also covered crowdedly with polyp-cells; texture of
the coral in its interior mostly solid.
3. Porites.—Corals often branched; the branches blunt; surface nearly smooth,
covered throughout with polyp-cells less than a line in diameter; some of the
species massive, irregularly globular, and occasionally ten or fifteen feet in
diameter; texture of the coral very finely cellular.
4. Astrea.—Corals massive, usually hemispherical, covered with radiated
polyp-cells, often half an inch or more in diameter; the hemispheres sometimes
fifteen or twenty feet in diameter.
5. Meandrina.—Corals as in the Astrea group in form and size, but surface
covered with meandering furrows, often a quarter of an inch or more in width.
Often called brain-coral, in allusion to the meanderings in the surface of the
brain.
6. Millepora.—Corals branching, lamellar, massive; surface smooth; cells
exceedingly minute, and in the interior of the coral divided by horizontal par¬
titions (a characteristic called tabulate by Edwards).
Each of the polyp-cells in these corals corresponds to a separate animal or
polyp (p. 163). In the Madrepores, the polyps when expanded have twelve rays
or tentacles, with a diameter of an eighth to a quarter of an inch. Those
of the Pocillopore8 and Porites are also twelve-rayed, but smaller. The Astreas
have an indefinite number of rays or tentacles: in some species of the family
the expanded flower-like polyp is an inch or more in diameter. In the Mean-
drinas the polyps coalesce in lines ; there is a series of mouths along the centre
of each furrow, and a border of tentacles either side.
In the Millepores, as stated on page 162, the animals are Acalephs, and not
true polyps.
Another common group of corals is the Funrjia: they have the form of broad
circular or oblong disks. In many of the species the disk corresponds to a
single polyp, and has a diameter in some cases of ten or twelve inches.
CORAL FORMATIONS.
619
Corals of the different groups here mentioned grow together promiscuously at
different depths up to low-tide level. The largest Aslrens, Meandrinas, and
Poritcs, with many Madrepores and other kinds, have been seen by the author
constituting the upper part of the growing reef. At Tongatabu there were
single masses of Pontes twenty-five feet in diameter, along with Astreas and
Meandrinas ten to fifteen feet. But, while these different groups do not corre¬
spond to different zones in depth, there are, without doubt, species in them which
belong to the deeper waters, and others to the more shallow.
The Poritcs, and some species of the Astrea, Mndreporn, and Pocil/opora groups,
continue to grow a little above low-tide level, equal to about one-third the
height of the tide,—as they will endure a temporary exposure to the sun without
serious injury. The Poritcs is an especially hardy group; for the corals suffer
less from impurity or silt in the waters than the species of other groups.
All the reef-forming species grow within the limit of 100 feet. The Dcndro-
phyllise, and a few other kinds that grow at greater depths, contribute but little
to the formation of reefs.
The polyp-corals have the power of growing indefinitely upward, while
death is going on at equal rate either at the base of the structure (as in the
moss of which peat is made) or through its interior, and are only stopped in
upward progress by reaching the surface of the water. The hemispherical
Astreas, many feet in diameter, although covered throughout with living
polj'ps, may be alive to a depth of only half or three-quarters of an inch,
and the huge Porites to a depth of less than a quarter of an inch : that is,
only a thin exterior portion of the mass is really living.
Besides corals and shells, there are also some kinds of calcareous
vegetation, called Nulliporcs, both branching and incrusting in
form, which add to the accumulation. They grow well over the
edge of the reef, in the face of the breakers, and attain consider¬
able thickness.
Action of the waves.—The waves, especially in their heavier move¬
ments, sweeping over the coral plantations, may be as destructive as
winds over forests. They tear up the corals, and, by incessant tritu¬
ration, reduce the fragments to a great extent to sand; and the
debris thus made and ever making is scattered over the bottom,
or piled upon the coast by the tide, or swept over the lower parts
of the reef into the lagoon. The corals keep growing, and this
sand and the fragments go on accumulating; the consolidation
of the fragmental material makes the ordinary reef-rock. Thus,
by the help of the waves, a solid reef-structure is formed from
the sparsely-growing corals.
Where the corals are protected from the waves, they grow up
bodily to the surface, and make a weak, open structure, instead
of the solid reef-rock ; or, if it be a closely-branching species, so as
to be firm, it still wants the compactness of the reef that has been
formed amid the waves.
620
DYNAMICAL GEOLOGY.
History of the emerging reef.—The growing corals and the accumu¬
lating debris reach at last low-tide level. The corals then mostly
die; but the waves continue to pile up on the reef the sand and
pebbles and broken masses of coral,— some of the masses even
two or three hundred cubic feet in size,—and a field of rough
rocks begins to appear above the waves. Next a beach is com¬
pleted, and the sands, now mostly above the salt water, are planted
by the waves with seeds, and trailing shrubs spring up ; after¬
wards, as the soil deepens, palms and other trees rise into forests,
and the atoll comes forth finished.
The windward side of such islands is the highest, because here
the winds and waves act most powerfully ; and where the leeward
side of one part of the year is the windward of another, there
may not be much difference between the two. The water that
is driven by the winds or tides over the reef into the lagoon
tends, by its escape, to keep one or more passages open, which,
when sufficiently deep, make entrances for shipping.
2. Coral Reefs.
The coral reefs around other lands or islands rest on the bottom
along the shores. They are either fringing or barrier reefs, according
Fig. 852.
View of a high island with barrier and fringing reefs.
to their position. Fringmg reefs are attached directly to the shore ;
while barrier reefs, like artificial moles, are separated from the
shore by a channel of water.
Fig. 852 represents an island with a fringing reef (/) and a bar¬
rier (b), and an intervening channel. Just to the right of the middle
the reef is wanting, because of the depth of water, and farther to
the right there is only a fringing reef. Fig. 854 is a map of an island
with a fringing reef, and figs. 855-857, others with barrier reefs. At
two points through the barrier reef in fig. 852 there are openings
to harbors (h). Such harbors are common, and generally excellent.
The channels uniting them around an island are sometimes deep
CORAL FORMATIONS.
621
enough for ship-navigation, and occasionally, as off eastern Aus¬
tralia, fifty or sixty miles wide. On the other hand, they may be
too shallow for boats; in which case the barrier-reefs coalesce with
the fringing reefs.
The barrier sometimes becomes wooded for long distances, like
the reef of an atoll ; but usually the wooded portion, when there
is any at all, is confined to a few islets.
The barrier and fringing reefs are formed precisely like the atoll
reefs; and special explanations are needless.
The absence of reefs from parts of coasts of islands within coral-reef seas
is due to several causes:—(1) to the depth of water, for corals fail if the depth
exceeds one hundred feet; (2) to fresh-water streams, especially if bringing in
detritus, which destroys the living corals; as such fresh waters flow over the
surface of the salt, they do not prevent the corals from growing below, unless
impure with detritus; (3) tidal and other currents which keep passages open,
by means of the detritus they often bear along their course. These are the
principal causes that prevent the harbors from becoming filled with corals and
thereby destroyed.
The growth of the different parts of a reef, or its prolongation in one direc¬
tion or another, depends much on the tidal and other currents that sweep
through the channel or by the side of the island. As in the case of silt along
other sea-shores, the coral detritus made by the waves is distributed by these
currents; and hence the increase of a reef is not dependent solely on the number
of growing corals over its surface, or their kinds.
Breadth of reefs.—The reefs adjoining lands have sometimes great
width. On the north side of the Feejees the reef-grounds are five to
fifteen miles in width. In New Caledonia they extend one hun¬
dred and fifty miles north of the island, and fifty south, making a
total length of four hundred miles. Along northeastern Australia
they stretch on, although with many interruptions, for one thou¬
sand miles, and often at a distance, as just stated, of fifty or sixty
miles from the coast, with a depth between of fifty or sixty fathoms.
But the reefs as they appear at the surface, even over the widest
reef-grounds, are in patches, seldom over a mile or two broad.
The patches of a single reef-ground are. however, connected by the
coral basement beneath them, which is struck, in sounding, at a
depth usually of ten to forty or fifty feet.
The transition in the inner channels from a bottom of coral detri¬
tus to one of common mud or earth, derived from the hills of the
encircled island,is often very abrupt. Streams from the land bring
in this mud and distribute it according to their courses through
the channels.
Thickness of reefs.—The thickness of a coral formation is often
very great. From soundings within a short distance of coral
622
DYNAMICAL GEOLOGY.
islands, it is certain that this thickness is in some cases thousands
of feet. Within three-quarters of a mile of Clermont Tonnerre,
in a sounding made by Hudson, the lead struck and brought up an
instant at two thousand feet, and then fell off and ran out to three
thousand six hundred feet without finding bottom ; and seven miles
from the same island no bottom was found at six thousand feet.
The barrier-reefs remote from an island must stand in deep
water. Supposing the slope of the bottom at the Gambier Islands
only five degrees, we find, by a simple calculation, that the reef has
a thickness of twelve hundred feet. In a similar manner, we learn
that it must be at least two hundred and fifty feet at Tahiti, and
two or three thousand at the Feejees.
3. Origin of tiie Forms of Reefs,—tiie Atoll and the distant
Barrier.
The origin of the atoll form of reefs was first explained by the
geological traveller Charles Darwin. According to the theory, each
atoll began as a fringing reef around an ordinary island; and the
slow sinking of the island till it disappeared, while the reef con¬
tinued to grow upward, left the reef at the surface a ring of coral
around a lake.
The proofs are—
1. As corals grow only within depths not greater than one hun¬
dred feet, the bottom on which they began must have been no
deeper than this; and, as such a shallow depth is to be found, with
rare exceptions, only around the shores of lands or islands, the reef
formed would be at first nothing but a fringing reef.
2. A fringing reef being the first step in coral formations, slow
subsidence would make it a barrier-reef.
In fig. 853 a section of a high island with its coral reefs is repre-
Fig. 853.
sented, the horizontal line 1 being the level of the sea, / a section
of the fringing reef on the left, and /' of the reef on the right.
CORAL FORMATIONS.
623
The growing reef depends for its upward progress on the growth
of the coral, and the waves. The waves act only on the outer
margin of a reef, while the dirt and fresh water of the land directly
retard the inner part. Hence the outer portion would increase
the most rapidly, and would retain itself at the surface during a
slow subsidence that would submerge the inner portion. The first
step, therefore, in such a subsidence is to change a fringing reef
into a barrier-reef (or one with a channel of water separating it from
the shore). The continued subsidence would widen and deepen
this channel; then, as the island began to disappear, the channel
would become a lake with a few peaks above its surface ; then a
single peak of the old land might be all that was left; and finally
this would disappear, and the coral reef come forth an atoll with
its lagoon complete.
Referring again to the figure: if in the subsidence the hori¬
zontal line 2 become the sea-level, the former fringing reef / is
now at b, a barrier reef, and f' is at 6/, and ch, chch" are sec¬
tions of parts of the broad channel or area of water within ; over
one of the peaks, P, of the sinking island, there is an islet of
coral i: when the subsidence has made the horizontal line 3
the sea-level, the former land has wholly disappeared, leaving
the barrier-reef t, V alone at the surface around a lagoon III,
with an islet, v, over the peak T, which was the last point to dis¬
appear.
These steps are well illustrated at the Feejees. The island Goro
(fig. 854) has a fringing reef; Augau (fig. 855), a barrier ; Exploring
Isles (fig. 85G), a very distant
barrier, with a few islets; Nu-
muku (fig. 857), a lake with a
single rock. The disappear¬
ance of this last rock would
make the island a true atoll.
Whenever the subsidence
ceases, the waves build up the
land above the reach of the
tides seeds take root and the Islands of tbe Feejee group: Fig' 854' Goro:
tides, seecis take root, and tiie 855^ Augau; 856) Exploriug Islos. 857) Nu_
reef becomes covered with fo- muku.
liage.
The atoll MenchikofF (fig. 850) was evidently formed, as ex¬
plained by Darwin, about a high island consisting of two distinct
ridges or clusters of summits, like Maui and Oahu in the Hawaian
group.
If the subsidence be still continued after the formation of the
Figs. 854-857.
s >
i 4
V-'-cV*
(324
DYNAMICAL GEOLOGY.
atoll, the coral island will gradually diminish its diameter, until
finally it may be reduced to a mere sand-bank or become sub¬
merged in the depths of the ocean.
The rate of subsidence required to produce these results cannot exceed the
rate of upward increase of the reef-ground. On page 591 some estimates are
given with regard to the exceeding slowness of the movement.*
As coral debris is distributed by the waves and currents according to the
same laws that govern the deposition of silt on sea-coasts, it docs not necessa¬
rily follow that the existence of a reef in the form of a barrier is evidence of sub¬
sidence in that region. On page 662 the existence of sand-barriers of similar
position is shown to be a common feature of coasts like that of eastern North
America. In the cases of the barriers about the islands of the Pacific, however,
there is no question on this point. Such barriers do not form about so small
islands. Moreover, the great distances of the reefs from the shores, in many
cases, and the existence of islands representing all the steps between that with
a fringing reef and the true atoll, leave no room for doubt. The remoteness
of the Australian barrier from the continent, and the great depth of water in
the wide channel, show that this reef is unquestionable proof of a subsidence,—
though it is not easy to determine the amount. Along the shores of continents
the question whether a barrier coral reef is evidence of subsidence or not must
be decided by the facts connected with each special case. (See Appendix E.)
Recapitulation.—The following are some of the points connected
with the formation of limestone strata illustrated by coral reefs:—
1. The narrow geographical limits of coral-reef rocks at the pre¬
sent time owing to the existing zones of oceanic temperature.
2. The narrow limit in depth of the reef-making corals,—it not
exceeding 100 feet.
3. The promiscuous growth of the corals over the reef-grounds.
4. The perfect compactness and freedom from fossils of a large
proportion of the coral rock, although made within a few hundred
feet of living corals and shells ; the oolitic structure of part of this
compact kind; while a variety made of broken corals cemented
together is common on the seaward side of a reef, and another,
made of standing corals with the interstices filled,forms where there
is shelter from the ocean's waves.
5. The aid of the waves of the ocean necessary for making a
* For further information on the subject of Corals and Coral Islands, the
reader may refer to the author's Exploring Expedition Report on Zoophytes,
740 pp. 4to and 61 plates in folio, 1846, and to the chapter on the Formation
of Coral Reefs and Islands in his Exploring Expedition Geological Report,
755 pp. 4to and 21 pi. fol., 1849; also to Darwin on the Structure and Distri¬
bution of Coral Reefs, 214 pp. 8vo, with maps and illustrations, London, 1842;
also to a memoir by Professor Agassiz.
COHESIVE ATTRACTION.
625
solid limestone out of corals or ordinary marine shells, and hence
their formation at great depths impossible.
6. The great extent and thickness of single reefs.
7. The action of tidal currents and those arising from the piling
in of the waves during stormy weather, in keeping open chan¬
nels and hai'bors, and determining the distribution of the coral
detritus.
8. The close proximity, along shores bordered by barrier-reefs,
of deposits of coral material, and deposits of river or ordinary shore
detritus.
9. An exceedingly slow subsidence in progress during the growth
of the corals the cause of the change of a fringing reef into a
barrier, and ultimately into an atoll.
10. The necessity of this subsidence for giving great thickness
to such limestones.
II. COHESIVE ATTRACTION—CRYSTALLIZATION.
The power of cohesion acting in solidification and that in crys¬
tallization appear to be identical. Snow, ice, bar-iron, trap, gra¬
nite, and even solid spermaceti, are crystallized in their intimate
structure. Iron and granite show it in the angular grains which
make up the mass, and which may be observed on a surface of
fracture; and ice, in the frosty covering of windows, and the prisms
which shoot across a surface on freezing, as well as in the vertical
columns into which it sometimes breaks when the ice of a pond
melts in spring. Quarts exhibits it in its prismatic and pyramidal
crystals (p. 55). The fact can thus be proved for all mineral
solids, except it be those of a glassy nature : and even these are
probably no exception to the principle that solidification is crystal¬
lization.
Crystallization is exhibited (1) in the angular solids it produces,
called crystals, and (2) in a tendency to cleave or divide in one or
more directions, called cleavage.
Crystals.—Some of the forms of crystals are illustrated on the
early pages of this work (pp. 55-65). Crystals are formed when
substances cool from fusion (as when melted sulphur cools) ; or
solidify from solution (as in the evaporation of a solution of alum);
or become condensed from the state of vapor (as in the formation
of snow from vapor of water). But it is requisite usually for per¬
fection that the process should go forward with extreme slowness,
free from all disturbing causes, and with space for the crystals to
41
626
DYNAMICAL GEOLOGY.
expand. Cavities in rooks are often lined with crystals, while the
rock itself is but a compact mass of crystalline grains.
Long-continued heat, short of fusion, favoring a slow aggrega¬
tion of the particles, sometimes produces crystals, or a crystalline
structure. Heating steel to a certain temperature changes the
fineness of the grains,—which is a change of crystalline texture
without fusion.
Cleavage.—Cleavage is usually parallel to one or more planes or
diagonals of the fundamental form.
The minerals mica and gypsum are examples of very easy cleavage.
Calcite has easy cleavage in three directions making a fixed angle
(105° 5') with one another parallel to the faces of the fundamental
rhombohedron. Feldspar has easy cleavage in one direction, and in
another a second cleavage, a little less perfect, at right angles, or
nearly so, with the first. Quartz has no distinct cleavage.
Cleavage in rocks.— Rocks may derive a cleavage-structure from
one of the constituent minerals. Thus, mica schist cleaves into
thin lamime because of the abundance of the very cleavable mine¬
ral mica. Mica may give cleavage even to a quartz rock. Gra¬
nite often has a direction of easiest fracture, due to the fact that
the feldspar crystals have approximately a uniform position in
the rock, bringing the cleavage-planes into parallelism.
Cleavage-structure must not be confounded with the existence
of planes of fracture in rocks, called joints. Mineral coal, trap,
sandstone, often break into angular blocks; but were there true
cleavage, the cleavage-structure would be general along some
one or more fixed directions in the mass or block, and not be
limited to certain planes of fracture. Cleavage follows particular
directions, but not particular planes.
The cleavage-structure of a rock like mica schist, due to a cleav¬
able mineral, is usually called foliation, to distinguish this character
from slaty cleavage, (see p. 101).
Concretionary structure.— Examples of concretionary forms are
given on pages 90-99. There is a general tendency in matter
to concrete around centres, whether solidifying from fusion, solu¬
tion, or vapors. These centres may be determined (1) by foreign
substances which act as nuclei, or (2) by the circumstances of
solidification, which, according to a general law, favor a commence¬
ment of the process at certain points in the mass assumed at the
time. As the solidifying condition is just being reached, instead
of the whole simultaneously concreting, the process generally be¬
gins at points through the mass, and these points are the centres
of the concretions into which the mass solidifies.
COHESION — CONCRETIONS.
627
The concretions in the same mass are usually nearly equal:
hence (3) the points at which solidification in any special case
begins are usually nearly equidistant. The great uniformity of
size in the concretions of most beds of rock shows that foreign
bodies do not generally determine the positions of the centres,
although they often act as nuclei.
Basaltic columns are a result of concretionary structure formed
in cooling (p. 98), in accordance with the principles just ex¬
plained : each column corresponds to separate concretionary
action. The size of the columns is determined by the distance
apart of the points which take the lead (these points lying in the
centres of the columns); and this is determined by the rate of
cooling; and this, mainly, by the thickness of the mass to be
cooled : the thicker the mass, the larger the columns. The cracks
separating the columns from one another are due to contraction
on cooling.
Iron-stone, sandstone, and clayey concretions in beds of rock, are
examples in which the concreting is due to a mineral solution
penetrating a stratum of clay or sand. A solution containing
silica would make siliceous concretions: so also carbonate of lime
in solution, or a ferruginous solution, may bo the concreting agent.
In either case the process is as has been explained: the distances
between the centres, being first fixed in the concreting process,
determine the size of the concretions, and the equality of these
distances the uniformity of size.
Spherical and flattened concretions.—A mineral solution (or any
liquid) naturally spreads equally in all directions through a sandy
or earthy stratum, and makes, therefore, spherical concretions ; but
in a clayey rock it spreads laterally most rapidly, and so leads to
flattened concretions. The vertical and horizontal diameters of
the concretions will be to one another as the rate of spreading in
the two directions.
Hollow concretions.—Flattened rings.—In a concretionary mass, the
drying of the exterior by absorption around may lead to its con¬
creting first. It then forms a shell with a wet unsolidified interior.
The drying of the interior, since the shell is unyielding, contracts
it, and consequently it becomes much cracked, as in figs. 72, 73;
or, if the interior undergoes no solidification, it may remain as
loose earth; or, if it solidify at the centre by the concreting pro¬
cess before the shell forms, or after, it may form a ball within a
shell, with loose earth between.
The circumstances that would produce hollow balls among sphe¬
roidal concretions produce rings among flattened concretions or in
628
DYNAMICAL GEOLOGY.
clayey layers. They arise from the solidification commencing first
around the circumference of the concretions, and then the circle
thus begun acting as a nucleus about which the concreting is con¬
tinued.
III. THE ATMOSPHERE.
The following are some of the mechanical effects connected with
the movements of the atmosphere.
1. Destructive effects from the transportation of sand, dust, etc.—The
streets of most cities, as well as the roads of the country, in a dry
summer day, afford examples of the drift of dust by the winds.
The dust is borne most abundantly in the direction of the preva¬
lent winds, and may in the course of time make deep beds. The
dust that finds its way through the windows into a neglected room
indicates what may be done in the progress of centuries where cir¬
cumstances are more favorable.
The moving sands of a desert or sea-coast are the more important
examples of this kind of action.
On sea-shores, where there is a sea-beach, the loose sands com¬
posing it are driven inland by the winds into parallel ridges higher
than the beach, forming drift-sand hills. They are grouped some¬
what irregularly, owing to the course of the wind among them, and
little inequalities of compactness or protection from vegetation.
They form especially (1) where the sand is almost purely siliceous,
and therefore not at all adhesive even when wet, and not good for
giving root to grasses ; and (2) on windward coasts. They are com¬
mon on the windward side, and especially the projecting points,
even of a coral island, but never occur on the leewarcl side, unless
this side is the windward during some portion of the year. On the
north side of Oahu they are thirty feet high and made of coral sand.
Some of them, which stand still higher (owing to an, elevation of
the island), have been solidified, and they show, where cut through,
that they consist of thin layers lapjfing over one another; and they
evince also, by the abrupt changes of direction in the layers (see
fig. 61 /), that the growing hill was often cut partly down or through
by storms, and again and again completed itself after such disasters.
This style of lamination and irregularity is characteristic of the
drift-sand hills of all coasts. On the southern shore of Long Island
there are series of sand-hills of the kind described, extending along
for one hundred miles, and five to thirty feet high. They are par¬
tially anchored by straggling tufts of grass. The coast of New Jersey
down to the Chesapeake is similarly fronted by sand-hills. In Nor-
ATMOSPHERE.
629
folk, England, between Hunstanton and Weybourne, the sand-hills
are fifty to sixty feet high.
2. Additions to land by means of drift-sands.—The drift-sand hills are
a means of recovering lands from the sea. The appearance of a
bank at the water's edge off an estuary at the mouth of a stream is
followed by the formation of a beach, and then the raising of the
hills of sand by the winds, which enlarge till they sometimes close
up the estuary, exclude the tides, and thus aid in the recovery of
the land by the depositions of the river-detritus. Lyell observes
that at Yarmouth, England, thousands of acres of cultivated land
have thus been gained from a former estuary. In all such results
the action of the waves in first forming the beach is a very import¬
ant part of the whole.
3. Destructive effects of drift-sands.—Dunes.—Dunes are regions of
loose drift-sand near the sea. In Norfolk, England, between Hun¬
stanton and Weybourne, the drift-sands have travelled inland
with great destructive effects, burying farms and houses. They
reach, however, but a few miles from the coast-line, and were it not
that the sea-shore itself is being undermined by the waves, and is
thus moving landward, the effects would soon reach their limit.
In the desert latitudes, drift-sands are more extended in their
effects.
4. Dust-showers.-—Sands are sometimes taken up by whirlwinds or
in heavy gales into the higher regions of the atmosphere and
transported to great distances.
In 1812, volcanic ashes were carried from the island of St.Vincent
to Barbadoes, GO to 70 miles; ancl in 1835, from the volcano of Co-
seguina in Guatemala to Jamaica, 800 miles.
Showers of grayish and reddish dust sometimes fall on vessels in
the Atlantic off the African coast, and over southern Europe ; and
when they come down with rain they produce "blood-rains."
Ehrenberg has found that the dust of these showers is to a great
extent made up of microscopic organisms.* The figures on the
adjoining page represent the species from a single shower which
came down about Lyons on October 17, 1846. The amount which
fell at the time was estimated by Ehrenberg at 720,000 lbs.; and
about one-eighth consisted of these organisms, making 90,000 lbs.
of them.
The species figured by Ehrenberg include thirty-nine species of siliceous Di¬
atoms (figs. 1-65); twenty-five of what he calls Phytolitharia, only a few of
* See his work entitled " Passat-staub und Blut-regen,'' 4to, 1847, and Ainer.
Jour. Sci. [2] xi. 372.
630
DYNAMICAL GEOLOGY.
which are here given (figs. 66-78), besides three of Rhizopods. The names of
the Diatoms are as follow :—
Figs. 1-78 (858-936).
Figs. 1, 2, Meloaira granulala ; 3, M. decussata ; 4, M. Marchica; 5-7, M. dis-
tane; 8, 9, Coseinodiscus atmospherica ; 10, Coscinodiscus ?; 11, Trrtchelomonax
levis; 12, Campylodiscus Clypeus; 13-15, Gornphonema gracile; 16, 17, Coccone-
ATMOSPHERE.
631
ma eymbiforme; 18, Cymbella niaculata; 19,20, Epithemia longioornis (frustulc
of E. Argus); 21, 22, E. longicornis; 23, E. Argus ; 24, E. longicornis; 25, En-
notia granulata?; 26, E. zebrina? ; 27, Himantidium Monodon ? ; 28-32, Euno¬
tia amphioxys ; 33, 34, Epithemia gibberula ; 35, Eunotia zebrina ? ; 36, E. zygo-
don?; 37, Epithemia gibba ; 38, Eunotia tridenttda ; 39, E. ? lev is; 40, Himan¬
tidium Areua; 41, 42, Tabelluria; 43, Odontidium ? ; 44, Cocconeis lineata ; 45,
C. atmospherica ; 46, Navicula Bacillutn ; 47, N. am phi ox ys ; 48, 49, N. Semen;
50, N. serians; 51, Pinmdaria borealis; 52, P. viridula ; 53, P. viridis; 54,
Mastogloia? ; 55, Pinmdaria aqnalis ?; 56, Surirella Craticula ? ; 57, 58, Synedra
Ulna; 59, Odontidium ? ; 60, Fragilaria pinnata ? ; 61, Mastogloia ? ; 62-65,
doubtful.
A shower which happened near the Cape Verdes, and has been
described by Darwin, had by his estimate a breadth of more than
1600 miles,—or, according to Tuckey, of 1800 miles,—and reached 800
or 1000 miles from the coast of Africa. These numbers give an area
of more than a million of square miles.
Dust from a shower over Italy in 1803 afforded Ehrenberg forty-
nine species of organisms, and another in 1813 over Calabria, sixty-
four species ; and the two had twenty-eight species in common.
In 1755, there was a "blood-rain" near Lago Maggiore in northern
Italy, covering about 200 square leagues; and at the same time
nine feet of reddish snow fell on the Alps. The earthy deposit in
some places was an inch deep. Supposing it to average but two
lines in depth, it would be for each square English mile an amount
equal to 2700 cubic feet. The red color of the " blood-rain" is owing
to the presence of some red oxyd of iron.
Ehrenberg enumerates a very large number of these showers, re¬
ferring to Homer's Iliad for one of the earliest known, and asks,
With such facts before us, how many thousand millions of hundred¬
weight of microscopic organisms have reached the earth since the
period of Homer? The whole number of species made out is
over 300.
The species, as far as ascertained, are not African ; fifteen are
South American. But the origin of the dust is yet unknown. The
zone in which these showers occur covers southern Europe and
northern Africa with the adjoining portion of the Atlantic, and
the corresponding latitudes in western and middle Asia.
5. Sand-scratches.—The sands carried by the winds, when passing
over rocks, sometimes wear them smooth, or cover the surface
with scratches and furrows, as observed by Wm. P. Blake over
granite rocks at the Pass of San Bernardino in California. Even
quartz was polished, and garnets were left projecting upon pedicels
of feldspar. Limestone was so much worn as to look as if the sur¬
face had been removed by solution. Glass in windows on Cape Cod
sometimes has holes worn through by the same means. (J.Wyman.)
682
DYNAMICAL GEOLOGY.
6. Changes of atmospheric pressure.—A local change of atmospheric
pressure from a passing storm has an effect on any large body of
water beneath it, a diminution of pressure causing the water di¬
rectly beneath to rise from the greater pressure elsewhere. A
variation of one inch in the mercury column of a barometer is
equivalent to 13.4 inches in a column of water. Captain J. C. Ross
has observed in the Arctic regions that a change of pressure of this
kind was perceptible in the tides. Observations through forty-seven
days gave a variation in the water of nine inches, corresponding to
two-thirds of an inch in the barometer.
The wind during storms produces sometimes an elevation of the
water in the leeward part of a lake at the expense of that in the
other, as has often been observed in the great lakes of North Ame¬
rica. Great waves on the ocean and extraordinary tides on sea-
coasts are other effects of the same cause. The subject of waves is
treated of under the head of Water.
IV. WATER.
Subdivisions of the subject.
1. Fresh waters; including especially Rivers and the smaller
Lakes.
2. The Ocean ; including the larger lakes, whether salt or fresh¬
water,—the general facts being similar, excepting such as depend
on the tides, and the kind and density of the water.
3. Frozen waters, or Glaciers and Icebergs.
1. FRESH WATERS.
The Superficial waters and the Subterranean may be separately
considered.
A. SUPERFICIAL WATERS, OR RIVERS.
1. General Observations on Rivers.
1. Water of rivers.—The fresh waters of the land come from the
vapors of the atmosphere, and these are largely furnished by the
ocean. They rise into the upper regions of the atmosphere, and,
becoming condensed into drops, descend about the hills and plains,
and so begin their geological work,—gravity being the moving
power.
The amount of water in a river depends on (1) the extent of the
RIVERS.
633
region it drains ; (2) the amount of rain, mist, or snow of the re¬
gion; (3) its climate,—heat and a dry atmosphere increasing the
loss by evaporation; (4) its geological nature,—absorbent and
cavernous rocks carrying off much of the water; (5) its physical
features,—a flat, open, unwooded country favoring evaporation.
The annual discharge of the Mississippi River averages nineteen
and a half trillions (19,500,000,000,000) of cubic feet, varying from
eleven trillions in dry years to twenty-seven trillions in wet years.
This amount is about one-quarter of that furnished by the rains. This
river is 3500 feet wide at St. Louis, 4000 off the Ohio, and about
2500 at New Orleans.
The mean annual discharge of the Missouri River is about three and three-
quarter trillions, or fifteen-hundredths of the amount of the rains over the region.
The corresponding amount for the Ohio is five trillions, which is one-quarter the
amount of rain. (Humphreys & Abbot.)
The rivers of some dry countries, as Australia, are great floods in
the rainy seasons and a string of pools in the dry.
2. Amount of pitch or descent in rivers.—The average descent of large
rivers, excluding regions of cascades, seldom exceeds twelve inches
to a mile, and is sometimes but half this amount.
The following facts on this point are from Humphreys & Abbot's Report on
the Mississippi Basin. The descent per inile is given in inches; L. stands for
the low-water slope, and H. for the high-water slope.
L. H.
Mississippi R. Mouth to Memphis (855 m.) 4.82 in. 5.23 in.
" Mouth to Cairo at mouth of Ohio (1088 m.) 6.94 5.96
" Above the Missouri to source (1330 m.) 11.74
Missouri R. Mouth to St. Joseph (484 m.) ' 9.24
" St. Joseph to Sioux City (358 m.) 10.32
" Sioux City to Fort Pierre (404 m.) 12.12
" Fort Pierre to Fort Union (648 m.) 13.20
" Fort Union to Fort Benton (750 m.) 10.56
Fort Benton is 2644 miles above the mouth of the Missouri. The whole
Missouri from its highest source, a distance of 2908 miles, has a descent of
about 6800 feet,—or 28 inches per mile.
During floods, the pitch of the surface of a stream is increased in
amount and uniformity. (1.) The waters are higher in the interior
of the country than near the ocean, because of the easy discharge
through its mouth. (2.) Owing to the height of the waters, which
often cover the banks, the course loses some of its minor bends,
and the whole distance is therefore less. (3.) The inequalities of
slope between the still water and more rapid portions mostly dis¬
appear. But when the river runs through a narrow, rocky gorge
034
DYNAMICAL GEOLOGY.
the waters above the entrance of the gorge are partially held back,
and have less slope during freshets than at low water; and conse¬
quently the pitch through the course of the gorge is increased.
3. Flow of a sire,am.—The above causes affect directly the velocity
of the stream, as this varies with the pitch and depth of water.
The sudden expansion in size and depth of a river-channel, as
when a lake intervenes, also affects the velocity, often producing
seemingly a state of nearly perfect quiet. The water-level becomes
for the interval nearly horizontal. R. Bakewell, Jr., accounts for
the quiet at the whirlpool in the rapids below the Falls of Niagara
on the ground of the great increase of depth and the abrupt expan¬
sion in breadth.
The movement of a stream is most rapid near the surface above
the line of deepest water. The bottom, sides, and air retard by
friction the layer in contact with them, and other adjoining layers
are retarded through the cohesion between the particles of the
water. The velocity is greater the less the extent of the upper
(or air) and bottom surfaces,—the surfaces of friction. When two
streams unite, the waters have the surfaces of friction of one
stream instead of two, and there is consequently an increased rate
of flow; besides, owing to the greater velocity, the united waters
do not occupy a space equal to the sum of those which they occu¬
pied before the union.
The velocities at different depths from the surface to the bottom being repre¬
sented by parallel lines drawn from a given base-line,
if the extremities of these lines be connected the curve
obtained is a parabola whose axis is parallel to the
water's surface and may be some distance below it,
and whose abscissa; vary as the velocities,—a princi¬
ple first established by Humphreys & Abbot. The
form of the parabola changes with the changing
depth and other conditions of a river. Fig. 937, from
the Report of these authors, shows the curve deduced
for the Mississippi at mean height, from observations
made in 1851 at Carrollton and Baton Rouge; « is the
surface ; b, the bottom ; a .r, the axis of the parabola.
They give other figures, representing the curve for
low and high water, and others also as deductions from each set of observa¬
tions. The axis, or line of greatest velocity, is nearest the surface at low water.
For the methods of experiment in determining the velocities, and for all details
on this important subject, and mathematical formulas connected with it, refer¬
ence should be made to the admirable " Report on the Physics and Hydraulics
of the Mississippi River," by Captain Humphreys and Lieutenant Abbot,
4to, 1861, based upon surveys and investigations made under acts of Congress,
directing the topographical and hydrographical survey of the Delta, &o.
Fig. 937.
RIVERS.
635
4. Force of running water.—According to Hopkins, the force of run¬
ning water varies as the sixth power of the velocity : so that doubling
the rate increases sixty-four times the force. If a stream running
ten miles an hour would just move a block of five tons' weight,
then a current of fifteen miles would move a similar block of fifty-
five tons; one of twenty miles, a block of three hundred and twenty
tons; while a current of two miles an hour, or three feet per second,
would move a pebble of similar form only a few ounces in weight;
at one foot per second, gravel; at six inches, fine sand; at three
inches, fine clay.
Other characteristics of rivers are brought out in the following
pages.
2. Mechanical Effects of Rivers.
The mechanical effects of fresh waters are,—
1. Erosion, or wear.
2. Transportation of earth, gravel, stones, etc.
3. Distribution of transported material, and the formation of
fragmental deposits.
1. Erosion.
1. General statement of the effects of erosion.—The effects of erosion
are seen, first, in the imprint of the falling rain-drop,—a trifling
matter to most eyes, but not so to the geologist; for it remains
among the records of the earliest and latest strata to show that it
rained then as now, and to teach us where the lands at the time
lay above the ocean. It is, therefore, a part of the markings in
which the geographical history of the globe is registered.
Second. The gathering drops make the rill, and the rill its little
furrow; rills combine into rivulets, and rivulets make a gully
down the hill-side ; rivulets unite to form torrents, and these work
with accumulating force, and excavate deep gorges in the declivi¬
ties. Other torrents form in the same manner about the mountain-
ridge, and pursue the same work of erosion until the slopes are a
series of valleys and ridges, and the summit a bold crest overlook¬
ing the eroding waters.
2. Progress of erosion in the formation of valleys or river-courses.—The
mist and rains about the higher parts of mountains are usually the
main source of the water. As the first-made streamlets are gather¬
ing into larger streams through the course of the descent, and are
largest below, the torrent has its greatest force towards the bottom
of the declivity, and there the valley first takes shape and size.
Let A B (fig. 938) represent a profile of a declivity. As the ero-
636
DYNAMICAL GEOLOGY.
sion goes on, a valley is formed along I rn, on the principle just
stated, so that the course of the waters on the profile corresponds
to A I m. At m, the most of the descent of the declivity is made ;
the waters have, therefore, but little eroding power at bottom, and
they flow off at a small angle to B, along the line m B. At m, more¬
over, the stream, ceasing to erode much at bottom, commences to
erode laterally during freshets, undermining the cliffs on either side
when the rocks admit of it, thus widening the valley and making
a "flood-plain" or "bottom-lands" through which the stream when
low has its winding channel.
The river, in this state, consists of its torrent-portion, A m, and its
river-portion, m B. Along the former a transverse section of the
valley is approximately V-shaped, and along the latter nearly U-
shaped, or else like a V flattened at bottom. The river-portion
usually exhibits, even in its incipient stages, its two prominent ele¬
ments,—a river-channel, occupied by the waters ip ordinary seasons,
and the alluvial fiat or flood-ground, which is mostly covered by the
higher freshets. The two go together whenever the course of the
stream is not over and between rocks that do not admit of much
lateral erosion and a widening thereby of the river-valley.
In the farther progress of the stream, A no becomes the torrent-
portion, and o B the river-portion. Later, the valley commences from
the summit A.
As the waters continue their work of erosion about the summits,
where the mists and rains are most abundant and often almost
perpetual through the year, the next step is the working down of
a precipice under the summit or towards the top of the declivity,
making the course of the waters A p q B, and, later, ArsB. The
stream in this state has (1) a cascade-portion, and (2) a torrent-portion; be¬
sides (3) its river-portion. The precipices thus formed are sometimes
thousands of feet in height; and the waters often descend them in
thready lines to unite below in the torrent. The mountain-top is
chiselled out by these means into a narrow, crest-like ridge. Each
separate descending rill frequently makes its own recess in the
Fig. 938.
Fig. 939.
A
RIVERS.
637
side of the precipice, and together they may face it with a series of
deep alcoves and projecting buttresses.
The next step in the progressing erosion is the wearing away of
the ridge that intervenes between two adjoining valleys. This
takes place about the higher portions nearest the mountain-crest,
where the descending waters are most abundant. Gradually the
ridge thins to a crest, and finally becomes worn away for some dis¬
tance, so that two valleys (or more by the wear of more ridges)
have a common head. In fig. 939, A r s B represents the course of
the stream, as in fig. 938 ; and A e / B the eroded ridge, which has
lost at e much of its height. The erosion, continuing its action
around the precipitous sides of the united head of the valleys, may
widen it into a vast mountain amphitheatre.
This is theoretically the history of valley-making, and the actual
history when the course is not modified by the structure of the rocks.
A model of this system of erosion is often admirably worked out
in the earthy slopes along a road-side,—the little rill having its
cascade-head, then its torrent-channel, and below its flat alluvial
plain with the winding rill-channel; some of the ridgelets in their
upper parts worn away until two or more little valleys coalesce;
then in some cases the head of the coalesced valleys widened into
an amphitheatre, and the walls fluted into a series of alcoves and
buttresses.
The system is illustrated on a grand scale among the old volcanic islands of
the Pacific, where the slope of the rocks at a small angle (5 to ] 0 degrees) from a
centre has favored a regular development. On Mount Kea (Hawaii), nearly
14,000 feet high, the valleys extend about half-way to the summit, having
made only this much progress upward since the volcano became extinct. On
Tahiti, the old mountain is reduced to a mere skeleton. The valleys lead up to
amphitheatres bounded by precipices of 2000 to 3000 feet, directly under the
peak; and the ridges between the valleys, though 1000 to 2000 feet high, are
reduced in the interior to mere knife-edges, impassable except as tliey are balus-
traded by shrubbery; and in some cases, adjoining the central heights, they are
worn down to a low wall or pinnacled crest, partially separating two of the
valleys. The traveller ascending one of the valleys along the bed of the stream
finds himself at last at the base of inaccessible heights, with numberless cascades
before him and a range of buttressed walls of remarkable grandeur.® Some¬
thing of this buttressed character of precipices is seen in fig. 941.
The nature of the rocks causes modifications in these results. If
there are harder beds at intervals in the course of the stream, or any
impediment to even wear, the impediment becomes the head of a
waterfall and precipice, whose height increases rapidly from the
* See the Author's Expl. Exped. Geol. Rep., p. 290, and Amer. Jour. Sci. [2]
ix. 48, and 289.
DYNAMICAL GEOLOGY.
force of the falling waters, until some other similar impedimenl
below limits the farther erosion. Thus many waterfalls and rapids
are made in the cascade-portion of a stream, and they are not ab¬
sent from the river-portion. Another effect of this cause is that
the stream is set back for some distance above a waterfall, and has
in this part more or less extensive flood-plains.
If the rocks are in horizontal strata and easily worn, the waters
work rapidly down to the level of the river-portion, so that the
cascade and torrent portion are each short or are hardly distin¬
guishable. The streamlets descending the walls of such soft rocks
will easily widen the head of the valley into an extensive amphi¬
theatre ; while in the farther course of the valley, beyond the limit
of the rainy region, the valley may be only a narrow gorge, hun¬
dreds, or perhaps thousands, of feet deep. Here in these depths
the stream meanders through a ribbon of alluvial land, rich in ver¬
dure at one season, and in others mostly flooded. Examples of all
these peculiarities of river-valleys might be described from among
the rivers of North America, especially the streams of the Missis¬
sippi valley and those of the slopes of the Rocky Mountains, where
the rocks are in general stratified, and usually not far from hori¬
zontal in position.
The remarkable canon of the Colorado, between the meridians of 1110 and
115° W. long., has already been partly described on p. 569 from the account fur¬
nished by Dr. Newberry. The principal facts are these :—A length of 300 miles,
and through the whole nearly vertical walls of rock, 3000 to 6000 feet in height;
these rocks limestone and other strata of Carboniferous age, others of older
'Palaeozoic, and below these generally the solid granite, making from 500 to 1000
feet of the gorge; and in some places the granite rising in pinnacles out of the
waters of the stream; finally, all the tributaries or lateral streams with similar
profound gorges or chasms. The view represented in fig. 940 was taken at
the junction of the Colorado and the Green Rivers, near the meridian of 1131°.
It shows well the narrow and profound chasm in which the waters of the Colo¬
rado flow, although not doing justice to the depth, which at this place is about
3000 feet. Some distance up the stream the two rivers come together, the Colo¬
rado from far to the right, and Green River from the left; and everywhere over
the great plain there are the profound lateral chasms or side-canons of the tri¬
butaries.
Fig. 941 is another view from the same remarkable region, illustrating espe¬
cially the side-canons. It is from the excellent Report of Lieutenant J. C. Ives,
the commander of the expedition with which Dr. Newberry was connected,
and is one among many views equally grand and instructive given in this
Report.
Newberry attributes these profound gorges, and beyond doubt correctly, to
erosion, each stream having made its own channel. The cliffs are so high that in
general no undermining can set back the walls far enough to allow of alluvial
WATER.
639
plains along the bottom, even when the water is not too rapid; and when a
channel is cut in granite, lateral wear is always small.
In the more distant part of fig. 940 there is a higher level of rock,—the
Pig. 940.
Caflon of the Colorado near its junction with Green River.
overlying gypsiferous red sandstone (Triassic or Jurassic, p. 417). It is in
isolated tables, and in some places in columns, needles, and towers, the greater
part of the formation having been swept off by erosion, due partly at least to
fresh waters. Still farther to the east, beyond the range of the view, another
still more elevated level is formed by Cretaceous strata: the existing surface-
features are similar to those of the older red sandstone.
Owing to the rapid increase of ratio in the power of running
water attending increase of velocity, the eroding action of water
during freshets becomes immense.
Many examples are on record of gorges hundreds of feet deep
cut out of the solid rock by two or three centuries only of work.
Lyell mentions the case of the Simeto in Sicily, which had been
dammed up by an eruption of lavas in 1603. In two and a half
64U
DYNAMICAL GEOLOGY.
WATER.
641
centuries it had excavated a channel fifty to several hundred feet
deep, and in some parts forty to fifty feet wide, although the rock
is a hard solid basalt. The larger part of the valleys of the world
are formed entirely by running water. At Tahiti, where they are
one to three thousand feet deep, they all terminate before reach¬
ing the sea, showing that they have been formed while the land has
stood, as now, above the ocean.
The windings of the stream in large alluvial flats are most nume¬
rous where the current is exceedingly slow ; for slight obstacles
change the course, throwing the current from one side to the
other. Between the mouth of the Ohio and the Gulf of Mexico
(head of the Passes), the length of the Mississippi is 1080 miles, and
the actual distance, in a straight line about 500 miles.
Pot-holes are incident to the process of erosion when the waters
flow in rapids over a bed of hard rocks. Any obstacle causes the
waters to move in a whirl and carry around pebbles or stones, and,
by this grinding process, circular pits or basins are worn in the
solid rock. The " Basin" in the Franconia Notch (White Moun¬
tains) is a pot-hole in granite, fifteen feet deep and twenty and
twenty-five feet in its two diameters. There are many pot-holes at
Bellows Falls, on the Connecticut; others on the White River, in
the Green Mountains, and elsewhere. One of those on the White
River is fifteen feet deep and eighteen in diameter ; another, twelve
feet deep and twenty-six in diameter.
3. Flood-plain.—The facts connected with the flood-plains derive
a special importance from their bearing on the subject of terraces.
The breadth of the flood-plain of a stream depends (1) on the general fea¬
tures of a country, and (2) on the stream's capability of encroaching laterally
on the hills either side. In some cases this breadth is ten to twenty miles, and
even fifty miles along such rivers as the Sacramento. In the case of these broad
plains, the valley is seldom one of erosion simply, but generally a synclinal trough.
When a stream crosses a series of synclinal valleys, the flood-plain generally
expands as it enters each, and contracts at the passage from one to the other.
The surface of a flood-plain is only approximately flat. (1) The margin
along a stream is often higher than the part back of it; (2) some portions
are frequently within the reach of only the very highest freshets; (3) others
are quite low, and are sometimes occupied by ponds of water or lagoons
fed from the river by percolation through the soil. The variation of height
from these sources is often equal to two-thirds of the whole average height
of the flood-plain above the river. The surface is sometimes changed much
in height during freshets, by the wearing away of one part and the increase
of others.
The height and pitch of the flood-plain are essentially that of the stream at
flood-height, and will, therefore, be affected by the causes mentioned on page
42
642
DYNAMICAL GEOLOGY.
633. It will be comparatively low towards the ocean. It will be diminished
by any abrupt expansion of the river-valley, by which the waters spread late¬
rally to great distances and consequently have diminished vertical height,
Conversely, the height will be increased by a narrowing of the valley, and
especially before the entrance of a contracted gorge.
While, therefore, there is a general parallelism between a stream at low water
and its flood-plain, there are wide variations from this parallelism.
The occurrence of waterfalls in the course of a stream causes the flood-plain
above to stand at a higher level than that below, equal at least to the height
of the fall, and somewhat above this height if the fall occurs in a gorge,
which would set the waters back during a flood.
If the erosion of some thousands of years or less deepen the bed of a stream
fifty feet, the flood-plain would sink correspondingly to a lower level; and
thus, in the lapse of time, without other geographical change than the one
mentioned, a terrace would be formed, some portion of the old plain being
left, as would naturally happen, at its former height. If a waterfall were
gradually obliterated, the flood-plain would undergo a corresponding change.
If the barrier that caused the existence of a lake along a river were removed,
there would be a sinking of the river's channel, and a sinking by erosion
also of the flood-plain. If from any cause—as a mountain-slide—a barrier
were thrown across a stream and a lake made, the flood-waters would stand
at a correspondingly higher level than before, and would spread more widely,
making new flood-plains above the former level. If the progressing erosion
be very much less on one part of a stream than on another (from the nature
of the country, or that of the rocks, etc.), the changes in the level of the later
flood-plain would have the same differences. Small streams would, of course,
sink their channels by erosion less than the large ones to which they are
tributary, provided the pitch be the same and the bed similar in material; and
even a large pitch will not often compensate for a very great difference in the
amount of water.
These are changes in the flood-plain which may take place from the ordi¬
nary incidents to which rivers are exposed.
Finally, if a continent undergo an elevation, the pitch of the river is in¬
creased and new erosive power is given it; and with the progress of the eleva¬
tion new flood-plains would form at lower and lower levels. This subject is
already explained at length on page 556. The only case in which the river
would not have a greater pitch after such an elevation is when the coast-region
added by the elevation slopes seaward at the same angle with that of the
stream before the elevation, or at a less angle than this.
2. Transportation by rivers.
The transporting power of running water is mentioned on page 635.
The materials transported are (1) stones, pebbles, sand, and clay ;
(2) logs and leaves from the forests, and sometimes trees that have
been torn up or dislodged by the current; (3) mollusks, worms,
insects, attached to the logs or leaves; (4) occasionally larger ani-
WATER.
643
mals that have been surprised and drowned by freshets, or bones
that have been exhumed by the waters.
The fine earthy material deposited by streams, or their sediment, is
called silt, or detritus. In accordance with the law with regard to the
transporting power of water, stones and pebbles make the bed of
rapid streams, and in general earth or silt where the current is slow.
The amount of transportation going on over a continent is be¬
yond calculation. Streams are everywhere at work, rivers with
their large tributaries and their thousand little ones spreading
among all the hills and to the summits of every mountain.
And thus the whole surface of a continent is on the move towards
the oceans. In the rainy seasons the streams increase immensely
their force. Streamlets in the mountains that are almost dry in
summer become destructive torrents during the rains.
The process of transportation is also one of wear. The stones are
reduced to sand and fine earth by the friction. The silt is nothing
but the coarse material of the upper waters ground up. The soil
of the plains and sand of the sea-shore are the pulverized rocks
of the mountains,—running waters being the moving-power, and
the mutual friction of stone upon stone, or grain of sand upon
grain, the means of grinding. The word detritus means worn out,
and is well applied to river-depositions. On large rivers, stones
and pebbles disappear from the alluvium long before they reach
the sea, and partly for the reason here mentioned. The process
is sometimes aided by the partial decomposition of the rocks.
The amount of silt carried to the Mexican Gulf by the Mississippi,
according to the Delta Survey under Humphreys & Abbot, is
about l-1500th the weight of the water, or l-2900th its bulk ; equi¬
valent for an average year to 812,500,000,000 pounds, or a mass
one square mile in area and 241 feet deep.
The following tabic contains the ratio of sediment to water by weight, as ob¬
tained by the Delta Survey and also the results of other investigations. It
is from Humphreys A Abbot's Report (p. 148) :—
Ratio. Time.
Mississippi R., at Carrollton, by Delta Survey, 1 : 1808 12 mos., '51-'52.
" " " 1:1449 12 mos., '52-'53.
" Columbus, " 1 : 1321 9 mos., '58.
" Mouths, by Mr. Meade, 1 : 1250 2 mos., '38.
" " " Mr. Sidell, 1 : 1724 1S38.
" Various places, Prof.Riddell,l : 1245 14 days, summer of 1843.
" New Orleans, " 1 : 1155 35 days, summer of 1846.
Rhone, at Lyons, by Mr. Surell, 1 : 17000 1844.
" " Aries, Messrs. Gorsse & Subours, 1 : 2000 4 mos., 1808-9.
" in Delta, Mr. Surell, 1 : 2500
Ganges, by Mr. Everest, 1 : 510 12 mos.
644
DYNAMICAL GEOLOGY.
The bulk may be calculated by taking 1.9 as the specific gravity of the material.
The total annual discharge of sediment from the Ganges has been estimated
at 6,308,000,000 cubic feet.
Besides the material held in suspension, as these authors observe,
the Mississippi pushes along into the Gulf large quantities of earthy
matter ; and, from observations made by them, they estimate the
annual amount thus contributed to the Gulf to be about 750,000,000
cubic feet,—which would cover a square mile 27 feet deep; and
this, added to the 241 feet above, makes the total 208 feet.
The quantity of wood brought down by some American rivers
is very great. The well-known natural "raft" obstructing Red River
had a length, in 1854, of thirteen miles, and was increasing at the
rate of one and a half to two miles a year, from the annual
accessions. The lower end, which was then fifty-three miles above
Shreveport, had been gradually moving up stream from the decay
of the logs, and formerly was at Natchitoches, if not still farther
down the stream. Both this stream and others carry great num
bers of logs to the delta.
3. Distribution of transported material.
1. Alluvial formations in river-valleys.—Alluvial formations cover
usually a broad area on one or both sides of a river. They are in
general the basis of the flood-plain ; and the features of this plain,
as already described, are the exterior characteristics of the alluvium.
They are made from the material brought down by the stream,
especially during freshets, and consist of earth and clay, sometimes
thinly laminated, with some beds of pebbles, and occasionally
stones. These coarser beds are most abundant along the upper
portions of the stream, while towards the mouth—particularly in
the case of large rivers—the material may be wholly a fine silt.
Logs and leaves are in some cases distributed through alluvial
deposits, but always sparingly; for they are mostly destroyed
by wear or by decay. They rarely, if ever, accumulate in beds
fitted for making coal, being widely scattered by the currents.
Fresh-water and land shells are occasionally found in the beds.
Remains of other animals seldom escape destruction, unless buried
in a lagoon-portion of the flood-plain.
As the range of height within which river-waters can work has
narrow limits, the thickness of the alluvial formations made by a
stream, in any given condition of it, is necessarily small. Even the
whole of the river-flat above the level of its bottom may not have
been deposited by the river in its existing state; for the channel
WATER.
645
and flood-plain may be excavated in the alluvium of an earlier
period, so that the upper surface alone may be of recent origin
(p. 550). If, however, the land were undergoing a very slow subsi¬
dence, which should diminish the pitch of the stream, a deposition
of detritus would take place which would raise both its bed and
flood-plain, and the thickness might thus go on increasing as long
as the subsidence continued.
The deposition of detritus which takes place along the course of a river
usually raises the borders of the channel above the general level of the flood-
plain. Along the Lower Mississippi, the pitch of the plain away from the
river amounts, on an average, to seven feet for the first mile. (Humphreys
& Abbot.)
The earthy alluvium which is formed by a slow deposition of detritus con¬
sists of very thin even layers. A vibration or wave-movement in any waters
in which a sediment is falling tends to arrange that sediment in layers, each
layer corresponding to a wave, and showing by a difference of texture in its
under and upper portions the progress of the wave. In the case of accumula¬
tions from a rapid deposition or pressing forward of material, the lamination is
often wanting.
The pebbles or stones forming beds in the alluvium are brought in by the
upper waters and lateral tributaries during floods. The course of a tributary
across the river-plain is often marked by a wide bed of stones. The sweep of a
freshet over the earthy flood-plain may carry away the finer earth and leave a
surface of pebbles. The bank of a river struck by a strong current may in a
similar way be made pebbly, while the opposite is muddy or has a sand-bank
forming from the earth carried across.
Still other irregularities result from changes in the river-channel. The trans¬
fer of material from one side of a stream to the other ends often in making a
long bend, and finally in cutting off the bend and turning it into an island, and
ultimately into a part of the mainland by the filling up of the old channel.
The islands in the large rivers are also very unstable. In the Mississippi, as
Humphreys & Abbot observe, they often begin in the lodging of drift-wood on
a sand-bar: this causes the accumulation of detritus; a growth of willow suc¬
ceeds ; the height of the alluvium still increases, until finally the island reaches
the level of high water, or rises even above it, and becomes covered with a
growth of cotton-wood, willow, etc. By a similar process, the island may be
united to the mainland; or, "by a slight change of direction of the current, the
underlying sand-bar is washed away, the new-made land caves into the river,
and the island disappears."
2. Delta formations.—The larger part of the detritus of a river is car¬
ried to the ocean (or lake) into which it empties, and it goes to form
about the mouth of the stream more or less extensive flats. Such
flats, when large and intersected by a network of water-channels,
are called deltas; they reach a large size only where the tides are
quite small or are altogether wanting. They are formed from the
conjoined action of the river and the ocean, and are sometimes
646
DYNAMICAL GEOLOGY.
called fluvio-marine formations. Great streams, like the Amazon,
carry their muddy waters hundreds of miles into the ocean; but
far the greater part of the detritus, even in the case of the largest
rivers, is beaten back by the waves on soundings and by the shore-
currents, and either falls over the bottom or is thrown upon the
coast near by. In floods, the river-water of the Mississippi is dis¬
tinguishable in the Gulf at the distance of only twenty or twenty-
five miles from the bar ; in low water, at the distance of five or ten
miles. (Humphreys & Abbot.)
The eastern North American coast, from Texas to Florida, and
WATER.
647
from Florida to New Jersey, is nearly a continuous range of fluvio-
marine formations.
Only a single example—that of the Mississippi delta—need here be referred to.
The preceding map (fig. 942) presents its general features. It commences
below the mouth of Red River, where the Atchafalaya " bayou" begins,—tlio
first of the many side-channels that open through the great flats to the Gulf.
The whole area is about 12,300 square miles, and about one-third is a sea-marsh,
only two-thirds lying above the level of the Gulf.
On page 643 the amount of detritus is mentioned which the river annually
furnishes towards the extension of the delta.
According to Humphreys & Abbot, the outer crest of the bar of the Southwest
Pass (the principal one) of the Mississippi advances into the Gulf 338 feet, over
a width of 11,500 feet, annually ; and the erosive power is only about one-tenth of
its depositing power. The depth of the Gulf where the bar is now formed being
100 feet, the profile and other dimensions of the river, in connection with the
above-mentioned rate of deposit, give for the difference between the cubical con¬
tents of yearly deposit and erosion 255,000,000 cubic feet, or a mass one mile
square and nine feet thick : this, therefore, is the volume of earthy matter pushed
into the Gulf each year at the Southwest Pass. The quantities of earthy matter
pushed along by the several passes being in proportion to their volumes of dis¬
charge, the whole amount thus carried yearly to the Gulf is 750,000,000 cubic feet,
or a mass one mile square and twenty-seven feet thick. As the cubical contents
of the whole mass of the bar of the Southwest Pass are equal to a solid one mile
square and 490 feet thick, it would require fifty-five years to form the bar as it
now exists, or, in other words, to establish the equilibrium between the advancing
rates of erosion and deposit.
The deltas of the Nile, Ganges, Amazon, and other large streams are equally
interesting subjects of study. But it is not necessary to enter into details re¬
specting them in this place, as they illustrate no new principles.
As the forms and stratification of delta deposits depend partly upon wave-
action, this subject comes up again under the head of The Ocean.
B. SUBTERRANEAN WATERS.
It is an obvious fact that a considerable part of the water which
reaches the earth's surface descends into the soil and becomes in a
sense subterranean. But there are also subterranean streams,
which have their rise in hills and mountains, and are fed, like the
surface-rivers, by the rains and snows, and especially those that
fall about elevated regions. These waters become under-ground
streams by following the dip of tilted strata. The layers of sand¬
stones and limestones never fit together so closely but that waters
may find their way between them. The subterranean streams
usually flow over limestone or argillaceous strata, and not on
porous sandstones.
648
DYNAMICAL GEOLOGY.
All wells and springs are tappings of these subterranean waters.
The large size of some of these under-ground rivers is proved by-
direct observation in caverns, where they have the variety of cas¬
cades and quiet waters which characterizes the streams of the sur¬
face. The Mammoth Cave of Kentucky, and the Adelsberg, twenty-
two miles northeast of Trieste, are examples. And, again, some¬
times, as in the Jura Mountains of Switzerland, they come out of
the hills with sufficient force and volume to turn the wheel of a
large mill.
The outward flow of the under-ground waters of a continent pre¬
vents the in-flow of the salt water on sea-shores. Springs are com¬
mon on shores; occasionally their waters rise in large volume in a
harbor, or out at sea some miles distant from a coast.
If subterranean streams have their rise in elevated regions, their
inferior portions beneath the plains of a country must be under
great hydrostatic pressure ; and this should appear, whenever a
boring is made to the waters, by their rising above the surface in a
jet. Borings of this kind have been made in many parts of Europe
and America with this effect. They were first attempted in France,
and are called Artesian wells, from the district of Artois, in France,
where they were early used.
In fig. 943, let a b represent
an argillaceous stratum on
which the water descends,
and b c the boring ; bed is the
jet of water. The rise of the
jet falls far short of the height
of the source, because of the
great amount of friction along
the irregular rocky bed of the
stream, and also the resistance
of the air.
It is possible that in some cases subterranean waters may be
under pressure from a stratum of gas over them, which is sufficient
to send them to the surface without other aid.
The Artesian well of Grenelle, near the Hotel des Invalides, in Paris, is 2000
feet deep. At 1800 feet, water was struck, and it darted out to a height above
the surface of 112 feet and at the rate of nearly one million of gallons a day.
The pressure indicated by the jet was equal to that of a column of water 2612
feet high, or 1160 pounds to the square inch.
Another well, in Westphalia in Germany, is 2385 feet deep.
An Artesian boring at St. Louis has been carried to a depth of 2200 feet; but
the water obtained is not pure. One at Louisville, Kentucky, 2086 feet deep,
Fig. 943.
Section illustrating the origin of Artesian wells.
WATER.
649
supplies an abundance of water, though a little brackish. Several have been
made in New York City connected with manufactories. In California they have
been resorted to successfully for agricultural purposes.
Borings are often successful in alluvial regions fifty or one hundred miles
from any high land. A second boring in the same region sometimes seriously
lessens the amount of water afforded by the first, by giving the same subterra¬
nean stream a new place of exit. The layer from which the boring and jet
rise may be gradually worn through by the flow, and the water, or part of it,
become lost by being thus let off to a lower level.
The mechanical effects of subterranean waters are—(1) Erosion
and the consequent undermining of strata ; (2) Land-slides.
1. Erosion.—Running water will wear rocks under ground as well
as above, and may excavate a channel in the same way. Caverns
are made partly by erosion and partly by the dissolving action of
water. A common effect of such excavations is the production of
subsidences of the soil and overlying rocks, and the formation
of sink-holes. Small shakings of the earth may be a consequence
of the fractures of undermined strata.
2. Land-slides.—Land-slides are of three kinds :—
(1.) The mass of earth on a side-hill, having over its surface, it
may be, a growth of forest-trees, and, below, beds of gravel and
stones, may become so weighted with the waters of a heavy rain,
and so loosened below by the same means, as to slide down the
slope by gravity.
A slide of this kind occurred during a dark, stormy night in August, 1826,
in the White Mountains, back of the Willey House. It carried rocks, earth, and
trees from the heights to the valley, and left a deluge of stones over the country.
The frightened Willey family fled from the house, and were destroyed: the
house remains, as on an island in the rocky stream.
(2.) A clayey layer overlaid by other horizontal strata some¬
times becomes so softened by water from springs or rains that the
superincumbent mass by its weight alone presses it out laterally,
provided its escape is possible, and, sinking clown, takes its place.
Near Tivoli, on the Hudson River, a subsidence of this kind took place in
April, 1862. The land sunk down perpendicularly, leaving a straight wall
around the sunken area sixty or eighty feet in height. An equal area of
clay was forced out laterally underneath the shore of the river, forming a
point about an eighth of a mile in circuit, projecting into the cove. Part
of the surface remained as level as before, with the trees all standing. Three
days afterwards, the slide extended, partially breaking up the surface of the
region which had previously subsided, and making it appear as if an earth¬
quake had passed. The whole area measured three or four acres.
(3.) When the rocks are tilted and form the slope of a mountain,
the softening of a clayey or other layer underneath, in the manner
650
DYNAMICAL GEOLOGY.
just explained, may lead to a slide of the superincumbent beds
down the declivity.
In 1806, a destructive slide of this kind took place on the Rossberg, near
Goldau, in Switzerland, which covered a region several square miles in area
with masses of conglomerate, and overwhelmed a number of villages. The thick
outer stratum of the mountain moved bodily downward, and finally broke up
and covered the country with ruins, while other portions were buried in the
half-liquid clay that had underlaid it and was the cause of the catastrophe.
Similar subsidences of soil have taken place near Nice, on the Mediterranean.
On one occasion, the village of Roccabruna, with its castle, sunk, or rather slid
down, without disturbing or destroying the buildings upon the surface.
Besides (1) the transfer of rocks and earth, land-slides also cause
(2) a scratching or planing of slopes by the moving strata and
stones; (3) the burial of animal and vegetable life; (4) the folding
or crumpling of the clayey layer subjected to the pressure, where
the effect does not go so far as to produce its extrusion and destruc¬
tion. Such crumpled or folded beds of clay are not very uncom¬
mon in alluvial regions (fig. 977).
2. THE OCEAN.
1. OCEANIC FORCES.
The ocean exerts mechanical force by means of its—
1. General system of currents.
2. Tidal waves and currents.
3. Wind-waves and currents.
4. Earthquake-waves.
The ratio between the velocity of salt water and its force is the same as
for fresh water (p. 635); but in the application of the ratio there is
a difference arising from the greater density of the former,—its
specific gravity being onc-thirty-Jfth to one-fortieth more than that of
fresh water. Having determined the size of block that any given
velocity would be sufficient to transport, the size for other velo¬
cities may be deduced by means of the ratio referred to.
The specific gravity of sea-water varies for different parts of the ocean. For
the waters of the southern ocean, it is 1.02919; the northern, 1.02757; equator,
1.02777; Mediterranean Sea, 1.0293; Black Sea, 1.01418 (Marcet). In most
seas receiving large rivers, and in bays, the density is least. The specific gravity
of the water of East River, off New York City, at high tide, is 1.02038 (Beck).
1. General system of currents.
The system of oceanic currents is briefly explained on page 39.
It is part of the organic structure of the globe, irrespective of its
WATER.
(551
age or condition; for, whatever the temperature of the poles,
there must always have been a warmer tropics under the path of
the sun.
The prominent characteristics of these currents bearing on their
mechanical effects in geological history are the following:—
1. The rate of movement is slow.—The maximum velocity of the
Gulf Stream is five miles an hour, and the average less than one
mile and a half.
The Gulf Stream is most rapid off Florida, where the hourly rate is three to
five miles; off Sandy Hook, it is one mile and a half. The rate of flow of the
polar current is less than one mile an hour. Kane, while shut up in the Arctic,
was carried south by the current, some days, about half a mile an hour. The
great oceanic current of the eastern South Pacific varies from three miles an
hour to a fraction of a mile; and across the middle of the ocean it is barely
appreciable. The current in the Indian Ocean, where most rapid, has the hourly
rate of two miles and a quarter.
In past geological ages the rapidity of these great oceanic cur¬
rents must have been less than now, if there was any difference,
because of the less difference of temperature then between' the
equator and the poles.
2. The currents arc generally remote from coasts, and arc seldom appre¬
ciable where the depth is less than one hundred feet, and very feeble where
less than one hundred fathoms.—-Owing to the great depth of the
oceanic movement, the waters are diverted along the borders of
the oceans by the deep-sea slopes of the continents. In the case
of the Gulf Stream, these approach the coast at Cape Florida, and
somewhat nearly at Cape Ilatteras ; but off" New Jersey they are
eighty to one hundred miles distant; and here runs the western
limit of the stream.
The polar or Labrador current, which is mostly a sub-current,
comes to the surface along the same slope, west of the limit of the
Gulf Stream, and is slightly apparent on the coast plateau, but
rather by its temperature than by the movement of the waters.
The more western position of the limit of the polar current is ex¬
plained on page 41. The fact that it has not more rapid move¬
ment on the great shore-plateau is evidence that it belongs to
the deep water. This appears further in the current's underlying
the Gulf Stream, and its banding the stream with colder and
warmer waters, as shown by the Coast Survey under Professor
Bache. The observations of the survey have proved that there
are mountain-ridges apparently parallel with the Appalachians
along the course of the stream in its more southern part, and that
above these ridges the surface-waters are cooler, owing to the lifting
652
DYNAMICAL GEOLOGY.
upward of the polar current by the submarine elevations. The fact
that the cold waters produce a temperature of 35° F. at a depth of
six hundred fathoms off Havana (as stated by Bache) is proof of
the great magnitude of the polar current.
Where the current flows close along a coast or submarine bank,
or by an oceanic island, it may produce some effects.
3. As the position of the main flow of the currents is determined partly by
the trend of the continents, their courses may have been different in former
tune from what they are now, provided the continents, or large portions of
them, were sufficiently submerged.—Small subsidences would not suffice
to produce a diversion from their present courses, for the reason
just given. Even the barrier of Darien might be removed by sub¬
mergence to a depth of five hundred feet, and probably one thou¬
sand, without giving passage to much, if any, of the Gulf Stream.
If, however, the straits were so deeply sunk that the Gulf Stream
passed freely into the Pacific (the West India islands being also in
the depths of the ocean, as would be necessary for the result), a
great change would thereby be produced in the temperature both
of the Atlantic and Pacific,—a loss of heat to the former and a
gain to the latter (see Physiographic Chart). But no facts yet ob¬
served prove this supposition to have been a realized fact since the
opening of the Silurian age.
Besides the general system of currents which has been considered, there are
currents between the ocean and some confined seas opening into it, which are
due to the evaporation going on over the surface of those seas. The conse¬
quent diminution of water causes a flow from the ocean to supply the loss.
This happens at the Straits of Gibraltar opening into the Mediterranean. In
many seas of this kind the accessions from rivers more than supply the amount
removed by evaporation, and these produce an out-current at the entrance.
2. Tidal waves and currents.
1. Rise and fall of tides.—The simplest of tidal actions is the
periodical rising of the waters on a coast. The in-flow acts like a
dam in setting back the waters of springs and rivers. It floods
large areas on flat coasts, which are thereby made salt marshes.
The height of the tide is less in mid-ocean than along the conti¬
nents, and is greatly augmented where the two coast-lines con¬
verge, as on entering a bay, and especially where there is free
entrance to a channel from two directions. In the middle At¬
lantic, at St. Helena, it is two or three feet; at the Azores, three
feet; on the Atlantic coast of the United States, from five to twelve
feet; but in the Bay of Fundy. fifty to seventy feet. In the cen-
WATER.
653
tral Pacific, the height is two to four feet; and at Tahiti, high tide
occurs always at noon.
2. Translation character of the tidal waves.—The tidal waves which
succeed one another around the globe become appreciably trans¬
lation or propelling waves on soundings; and directly upon a
coast, especially along its deeper bays or inlets, they constitute a
force of great energy. The borders of all the continents and
islands feel this power and exhibit its effects.
3. In-flowing tidal currents.—The in-coming tide generally strikes
one part of a coast before another, owing to its trend with refer¬
ence to the wave, and, consequently, has a progressing movement
along it. This is very marked on the shores of southern New
England.
The tidal current becomes one of great strength where there are
narrow channels to receive and discharge the waters.
The movement may have the violence of a river-torrent when
the entrance to bays is of a kind to temporarily dam up the waters
until the far-advanced tide has so accumulated them that they
overcome the resistance and pass on in a body.
In the Bay of Fundy, the waters of the in-coming tide are raised
high above their natural elevation, so that as they advance they
seem to be pouring down a slope, making a turbid waterfall of
majestic extent and power, without foam. The tide at Bristol.
England, has a height of forty feet.
In some cases the whole tide moves in all at once, in a few great
waves. This happens especially at the mouths of rivers where there
is obstruction from sand-bars, and other favoring circumstances
about the entrance. The phenomenon is called an eagre or bore.
The flow of the tides at the Bay of Fundy has something of the
character of an eagre. But the most perfect examples are afforded
at the mouths of the rivers Amazon, Hooglv (one of the mouths of
the Ganges), and Tsien-tang in China. In the case of the last-
mentioned river the wave plunges on like an advancing cataract,
four or five miles in breadth and thirty feet high, and thus passes
up the stream, to a distance of eighty miles, at a rate of twenty-five
miles an hour. The change from ebb to flood tide is almost instan¬
taneous. Among the Chusan Islands, just south of the bay, the
tidal currents run through the funnel-shaped firth with a velocity
of sixteen miles an hour. (Macgowan.)
In the eagre of the Amazon, the whole tide passes up the stream
in five or six waves, following one another in rapid succession, and
each twelve to fifteen feet high.
4. Out-flowing currents.—The ebbing tide causes an out-flowing
654
DYNAMICAL GEOLOGY.
current, which is directly the counterpart of the in-flowing current.
It is more quiet than the latter in its movement, although often
a rapid and powerful current, because more contracted in width,—
and especially so in bays, where the waters of a river add to the
volume of the ebb. Wind-waves may increase greatly the force of
the in-coming tide, but not so with the out-flowing, since wives
always act shoreward.
The piling of the tidal waters to an unusual height in converging
bays, raising them far above their level outsidq, is another powerful
cause of out-flowing currents. The flow is along the bottom; and
in a case like that of the Bay of Fundy it must have great power.
3. Ordinary wind-waves and currents.
1. Waves.—The winds are almost an incessant wave-making
power. Even in the calmest weather there is some breaking of
wavelets against the rocky headlands or the exposed beach ; and
with ordinary breezes the beaches and rocks are ever under the
beating surge, night and day, from year to year. Most seas, more¬
over, have their storms, and in some, as those about Cape Horn,
gales prevail at all seasons. The breakers on the shores of the
Pacific are especially heavy, on account of its extent and depth.
Through a large part of the ocean the winds are constant in
direction, either for the year or half-year.
Stevenson, in his experiments at Skerryvore (west of Scotland),
found the average force of the waves for the five summer months
to be 611 pounds per square foot, and for the six winter months,
2086 pounds. He mentions that the Bell Rock Lighthouse, 112
feet high, is sometimes buried in spray from ground-swells when
there is no wind, and that on November 20, 1827, the spray was
thrown to a height of 117 feet,—equivalent to a pressure of nearly
three tons per square foot.
2. Surface-currents.—Winds also cause currents. The prevailing
winds of an ocean, like the trades (p. 44), cause a parallel move¬
ment in the surface-waters; and when the direction is reversed for
half the year, as in the western half of the tropical Pacific, the cur¬
rent is changed accordingly. These currents become marked along
shores, and especially through open channels. Prolonged storms
often produce their own currents, even in mid-ocean, and more
strikingly still among the bays and inlets of a coast.
These currents made by the winds are inferior in power to the
tidal currents among the inlets and islands of a continental coast;
but about oceanic islands they are often of greater strength.
WATER.
655
3. TJnder-cvrrents.—The forcing of waters into bays, whether by
regular winds or storms, causes a strong under-current outward, like
that from the tides. This is especially marked when the entrance
of the buy is broad, so as to allow of an in-flow over a wide area,
while the deep-water channel is narrow. In some cases, ships lying
at anchor feel this under-current so strongly as to " tail out" the
harbor in the face of a gale which is blowing in.
In the ordinary breaking of waves on a beach or in rocky coves,
there is an under-current (or under-tow) flowing outward along the
bottom. The wave advances and makes its plunge, and then its
waters flow back beneath those of the next wave, which is already
hastening on towards the beach.
4. Earthquake-waves.
In an earthquake, the movement of the earth may be either (1)
a simple vibration of a part of the earth's crust; or (2) a vibration
with actual elevation or subsidence. In each case, the ocean-waves
which the earthquake, if submarine, may produce, have an actual
forward impulse, and are, therefore, forced or translation ivaves. They
have great power ; and, as there is no narrow limit to the amount of
elevation which may attend an earthquake, such a wave may be of
enormous height. An earthquake at Concepcion, Chili, set in
motion a wave that traversed the ocean to the Society and Navi¬
gator Islands, 3000 and 4000 miles distant, and to the Hawaian
Islands, G000 miles; and on Hawaii it swept up the coast, tempo¬
rarily deluging the village of Hilo.
2. EFFECTS OF OCEANIC FORCES.
The effects of oceanic forces are here treated under the heads of—
(1) Erosion; (2) Transportation; (3) Distribution of Material, or
Marine and Fluvio-marine formations.
1. Erosion.
Erosion by currents.—But little erosion can be produced by the great
oceanic currents, on account of their slow rate of motion, and their
distance from the land. Still, the Labrador current, with its west¬
ward tendency (p. 41), acting against the submerged border of the
continent, may have produced some results of this kina in past time,
if not doing so now. It has been supposed that the course of the
steep outer slope of this submerged border (p. 12) has been deter-
656
DYNAMICAL GEOLOGY.
mined by the oceanic currents; but it is not probable that the po¬
sition of the slope has directed the courses of the currents.
The tidal flow and upper wind-currents may produce results similar
to those of fresh-water streams of equal velocity.
The ebbing tide and the under-currents act on the bottoms of inlets and
harbors, and especially their channels, and are an important means
of keeping them open to the ocean and of modelling their forms.
2. Erosion by waves.—The waves bring to bear the violence of a
cataract upon whatever is within their reach,—a cataract that girts
all the continents and oceanic islands. In stormy seas, they have
the force of a Niagara, but with far greater effects; for Niagara falls
into a watery abyss, while in the case of the waves the rocks are
made bare anew for each successive plunge. It is not surprising,
therefore, that in regions like Cape Horn or the coast of Scotland,
where storms are common and the bordering seas deep, the cliffs
should undergo constant degradation and be fronted by lofty cas¬
tellated and needle-shaped rocks. The action of the ordinary
breakers is sufficient to wear the rocky shores, reduce stones to
gravel and sand, and grind the sands of beaches to a finer powder.
The cliffs of Norfolk and Suffolk, England, afford an example that has been
long under observation, as the country is ono of houses and cultivated fields.
Lyell states that when the present inn at Sherringham was built, in 1S05, it was
fifty yards from the sea, and it was computed that it would require seventy
years for the sea to reach the spot,—the mean loss of land having been calcu¬
lated, from former experience, to be somewhat less than one yard annually.
But it was not considered that the slope of the ground was fiom the sea. Be¬
tween the years 1824 and 1829, seventeen yards were swept away, bringing the
waters to the foot of the garden; and in 1829 there was depth enough for a
frigate (twenty feet) at a spot where a cliff of fifty feet stood forty-eight years
before. Farther to the south, the ancient villages of Shipden, Wimpwell, and
Eccles have disappeared. This encroachment of the sea has been going on from
time immemorial. Many examples might be cited from the American coast,
but none as remarkable have yet been described.
These effects of the sea on coasts depend on (1) the height of the
tides ; (2) strength and direction of tidal currents ; (3) direction of
the prevalent winds and storms ; (4) force of the waves ; (5) nature
of the rock of the shores ; (G) outline of the coast.
Soft sandstones in horizontal layers, and beds of gravel or earth,
are easily removed. But granite, gneiss, quartz rock, and trap or
basalt, undergo usually but slow wear. Projecting headlands,
which stand out so that the sea can batter them from opposite
directions, are especially exposed to degradation, and particularly
those on windward coasts. «
3. The wearing action of waves on a coast is mainly confined to a height
WATER.
657
between high and low tides.—Since a wave is a body of water rising
above the general surface, and when thus elevated makes its plunge
on the shore, it follows that the upper line of wearing action may
be considerably above high-tide level.
Again, the lower limit of erosion is above low-tide level, for the
waves have their least force at low tide, and their greatest during
the progressing flood ; and when the waves are in full force, the
rocks below are already protected by the waters up to a level above
low-tide mark. There is, therefore, a level of greatest wear, which
is a little above half tide, and another of no wear, which is just
above low tide.
This feature of wave-action, and the reality of a line of no wear
above the level of low tide, are well illustrated by facts on the coasts
of Australia and New Zealand.
In figure 944 (representing in profile a cliff on the coast of New
South Wales near Port Jackson), the horizontal strata of the foot
of the cliff extend out in a platform a hundred yards beyond the
Fig. 944. Fig. 945.
Cliff, New South Wales. "The Old Hat," New Zealand.
cliff. The tide rises on the platform, and the waves, unable to
reach its rocks to tear them up, drive on to batter the lower part
of the cliff. At the Bay of Islands, New Zealand, the rocks have
no horizontal stratification, and, still, there is the same sea-shore
platform; and an island in the bay (fig. 945) is called " The Old
Ilat." The sea-shore platform of coral islands has the same origin.
The stability of sand-flats in the face of the sea is owing to this cause.
In seas of high tides ancl frequent storms, the platform is narrow
or wanting, owing to the tearing action of the heavy waves.
2. Transportation.
1. Transportation by currents.—The great oceanic currents are too
feeble to transport any material coarser than fine sand, and too
remote from coasts to receive detritus of any kind, except sparingly
from the very largest of rivers, like the Amazon. Whatever sinks
in the main course of the Gulf Stream is carried some distance
southward again by the polar current beneath it.
43
658
DYNAMICAL GEOLOGY.
Sea-weeds are borne on by the Gulf Stream in great quantities,
and thrown off on the inner side of the current into the great area
of still water about the centre of the North Atlantic, called, from
the common name of the plant (a species of Fucus), the Sargasso
Sea. With the sea-weeds, there is a profusion of small life,—fishes,
crabs, shrimps, Bryozoans, etc.
Pourtales, in microscopic examinations of soundings from beneath the Gulf
Stream, found an abundance of the shells of Rhizopods, and almost no proper
detritus. Bailey suggested that these minute cellular shells were drifted to their
pla^e by the stream; but Pourtales concludes, from his observations, that they
live at the depths in which they are found.
In polar seas, where there are glaciers and icebergs, large quan¬
tities of gravel, earth, and boulders are often floated off on the
bergs. From the Arctic they are borne south by the polar current
to the Banks of Newfoundland; there the icebergs encounter the
edge of the Gulf Stream, and melt, dropping their freight over the
bottom.
Tidal and wind currents have the same powers of transportation as
rivers of equal velocity.
2. Transportation by waves.—As follows from the force of waves
against shores, stated on p. 654, they have great transporting
power; but their action is confined to narrow limits of depth, and
is exerted mainly when the plunging waters strike and dash upon
a sandy or rocky coast. Large rocks often have their buoyancy
increased by the sea-weeds attached to them.
Stevenson reports that a block of gneiss of 504 cubic feet (about forty-two
tons) lying on a beach (in Scotland) was moved five feet by the waves during
one storm, and was then so wedged in that its farther progress was prevented.
The in-coming wave, as it struck it, gave it a shove, and, pushing on, buried it
from sight, making a perpendicular rise of thirty-nine or forty feet; and in the
back run the mass was again uplifted with a jerk.
Marine animals, or their relics, and sea-weeds, are thrown abun¬
dantly on coasts by the waves; and, in some regions, whales that
venture too near the land are carried up and left floundering on
the sand. This happens not unfrequently about the Chusan Islands
in the China Seas, where the tidal currents have great force (p.
653).
In the case of the heaviest waves, and especially earthquake-
waves, the waters first retreat to an unwonted distance, and then
advance in their might, striking deep, and tearing up strata that at
other times are under the protection of the waters.
In the wave-movement on soundings, and not close in-shore, the
propulsion of each wave is very small; and its power of accomplish-
WATER.
659
ing great transporting effects lies in its incessant action. The waves
thus beat back the detritus thrown out by rivers, and cause them
to be deposited mainly over tbe bottom in the shallower waters, and
against the shores, and so prevent their being lost to the land by
sinking in the depths of the ocean.
In the passage of the great wave of the eagre on the Tsien-tang (p. 653), the
boats floating in the middle of the stream rise and fall on the tumultuous
waters, but are carried only a very short distance forward. Yet,along the sides
of the river, the wave tears away the banks, and in places sends a. deluging flood
over the shores, a true tidal current, which devastates the country.
It follows, from the facts stated, that no continent can contribute
to the detrital accumulations of another continent except through
the aid of icebergs. Had there formerly existed a continent in the
midst of the present North Atlantic, America would have received
from it little or no rock-material. The tides and waves, and tidal
and wave currents, all work shoreward.
3. Distribution of material, and the formation of marine and
fluvio-marine deposits.
1. Oceanic Formations.
The deposits of oceanic currents consist only of fine detritus: no
conglomerates or coarse sandstones can, therefore, be made from
them. The Gulf Stream has little power in making such deposits,
as it carries along scarcely any detritus. The bottom of the Atlan¬
tic between Ireland and Newfoundland consists almost solely of
the shells of microscopic organisms (p.. G12).
By means of icebergs, the currents of the ocean may distribute
widely the coarsest of rock-material; but nearly all the icebergs
of the North Atlantic drop their loads of gravel and stone in the
vicinity of the American continent, and not in mid-ocean. The
deposits made by icebergs consist of gravel, sand, and stones of all
sizes, up to many tons in weight, promiscuously mingled, without
stratification. They are thus unlike all the rock-formations over
the continent preceding the period of the Post-tertiary.
Mr. Babbage has shown that, taking four kinds of detritus, of
such a size, shape, and density that they would sink—the. first kind 10
feet an hour, the second 8, the third. G, the fourth 4, then if a stream
containing this detritus were 100 feet deep at mouth, and entered
a sea having a uniform depth of 1000 feet, and a rate of motion of
two miles an hour, the first kind would be carried 180 miles before
660
DYNAMICAL GEOLOGY.
the first portions would reach bottom, and would be distributed
along for £0 miles ; the corresponding numbers for the others would
be—(2) 225 and 25 ; (3) 300 and 40; (4) 450 and 50. Thus, four kinds
of deposits would be formed from the same stream, at different dis¬
tances from its mouth.
2. Formations on Soundings and along Coasts.
1. Origin of the material.—The material of sea-sliore formations
is derived from two sources: (1) the detritus of rivers ; (2) the wear
of coasts.
All the rivers entering an ocean bring in more or less detritus,
especially during freshets. The quantity from the Mississippi is
stated on page G44. The amount thus contributed to the ocean
depends on the geographical extent of the river-systems bordering
it, and the annual amount of rain, snow, etc. In both these respects,
North and South America exceed the other continents; and the
ocean which receives the detritus is the Atlantic.
2. Distribution and accumulation.—The distribution and accumula¬
tion of the material may take place (1) from the action of waves
alone; (2) from waves, and tidal or wind currents; (3) from the
waves, the shore-currents, and the currents of rivers.
(1.) The accumulations made by waves are either in the form of
beaches or off-shore deposits of detritus. As the plunge of the
wave is analogous to that of a torrent, its waters, while grinding the
material upon which they act, wash out the finer portion, and carry
it away by means of the under-tow. The beach consequently
consists of more or less coarse material, according to the strength
of the waves: it may be sand, pebbles, or even large stones, if the
rocks of the coast are of a nature to afford them. In sheltered
bays, where the waves are small, trituration is gentle, and the mate¬
rial of the beach may be a fine mud or silt.
The height of a beach depends on the height of the tides and the
strength of the waves. The sands thrown beyond the farthest
reach of the waves are often accumulated into higher ridges, and
make the wind-drifts and dunes described on page 029.
(2.) .The tidal and wind currents give direction to the material taken
up by the waters. This material may be the sands, stones, etc. of a
beach, or the finer material from the bottom, or the mud stirred up
from greater depths, down even to 100 feet, by the heavy waves of
storms. The currents, their general course being otherwise deter¬
mined, flow where they find the freest and deepest passage, and
drop their detritus wherever there is a diminution of velocity. This
precipitation takes place in the waters thrown off either side of the
WATER.
661
current, and especially the shoreward side, towards which the waves
set the floating material; also where capes make a lateral eddy,
and where any obstruction tends to retard the waters. A vessel sunk
in the passage may divert the waters a little to one side, where they
may have an easier flow, and become itself the basis of an accumu¬
lating sand-bank.
The increase and shaping of a sand-spit depend usually on the
action of the in-flowing tidal current and waves on the outer side,
and that of the out-flowing on the inner, the latter being the deeper
and often the more effectual.
This point is well illustrated by Captain Davis in his excellent paper on the
geological effects of tidal action. lie mentions the cases of long points thus
made on the eastern extremity of Nantucket, where the current on the outside
of the island sets from the west to the east, and from the south to the north.
Vessels wrecked on the south side of the island have been carried by it, in
piecemeal, eastward, and then northward to the beach north of Sankaty Ilead.
The coal of a Philadelphia vessel, lost at the west end of the island, was carried
around by the same route to the northern extremity.
Where the wind-current changes semi-annually, the accumula¬
tions made by the current when flowing in one direction are some¬
times transferred to another side of an island or point during the
next half-year.
.T. D. Hague states, in a recent article, that at Baker Island (of coral), in the
Pacific (0° 15' N., 170° 22' W.), this fact
is well exhibited. In fig. 940, I I I is
the southwest point of the island, and
It R R, the outline of the coral-reef plat¬
form, mostly a little above low-tide
level; its width, c d, 100 yards. In the
summer season, when the wind is from
the southeast, the beach has the outline
«, s, s ; during the winter months, when
the wind is northeast, the material is
transferred around the point, and has
the position in, w, w, having a width at
a b of 200 feet. A vessel wrecked in
summer, and stranded at V, was trans¬
ferred to V in the course of the month of November.
(A) The combination of wave-action and marine currents with the cur¬
rents of rivers produces results tmalogous to those, proceeding from
marine currents and waves alone, but with greater complication,
and, in the present age, of far greater extent, because rivers add so
vastly to the material of deposits by their detritus.
The flow of rivers and the movements of the ocean are, in general.
Fig. 946.
602
DYNAMICAL GEOLOGY.
in direct opposition. The in-flowing tide sets back the rivers, quiets
the waters, and floods the adjoining tidal flats; and consequently a
deposition of detritus takes place over the flats, and the bed of the
stream. The turn of the tide sets the river again in full movement,
and it takes up the detritus deposited over its bed (but only little
of what fell over the flats) and bears it to the ocean. Here the cur¬
rent loses much of its velocity in the face of the waves and with the
spreading of the waters, and hence a deposition of detritus goes on :
this continues until the next tidal flow dams up the fresh-water
stream anew. Between the ocean and the river there is a region
of comparative equilibrium in
the two movements, and there
the accumulations of sand or
detritus take place, forming
sand-bars.
Humphreys and Abbot observe, in
speaking of the Mississippi delta,
that as the river-water rises above
the salt water, from its low density,
there is a dead angle between the
two. The current out the Passes
pushes sand and earth before it, un¬
til, reaching, it begins to ascend upon,
the salt water of the Gulf, and here
this material "is left upon the bot¬
tom in the dead angle of salt water.
A deposit is thus formed, whose sur¬
face is along or near the line upon
which the fresh water rises on the
salt water as it enters the Gulf; and
this action produces the bar."
The distance off the mouth
of a river of these sand bars or
barriers will depend on the
size and strength of the rivers
on one side, and the height and
force of the tides on the other.
,, ,, iiii Fluvio-marine formation along the coast of
Small streams are often blocked North Carolina
up entirely by a.sand-bar across
their mouths, and the waters reach the ocean only by percolation
through the beach. Large streams make distant sand reefs and
barriers even in the face of the ocean. The North American coast
from Long Island to Florida is fronted by ranges of barrier reefs
shutting in extended sounds or narrow lagoons.
WATER,
G63
The accompanying map of Pamlico Sound and the region about
Cape Ilatteras (fig. 947) illustrates this feature of the continent.
The numerous rivers of this well-watered coast carry great quan¬
tities of detritus to the ocean,—part of which is borne out to sea to
raise the great submarine plateau of the coast, and another part is
added to the barrier and to the banks and flats of the Sound. The
contraction of the Sound, which is going on by the additions to the
flats and over its bottom, gradually prolongs the channel of the
river towards the ocean. This gives greater force to the river-cur¬
rent, and it acts in conjunction with the strong ebb tide against the
inner side of the barrier, in slowly wearing it away. At the same
time, the outflowing stream and tidal current carry a greater quan¬
tity of detritus into the ocean, contributing sand to the beach and
finer detritus to the plateau, the nature of wave-action on a beach
being such as to leave only the sand or coarser material. Thus, by
a slow process, the mainland gains in breadth, and the river in
length, and the barrier moves gradually seaward. In other cases,
the lagoons inside of the barrier become filled, and a continuous
marsh, and ultimately dry land, is made out to the barrier. All the
low lands along the eastern coast of the continent, and that border¬
ing on the Gulf of Mexico, in most parts many scores of miles in
breadth, have been made in the manner here pointed out.
When the tides are very small, or fail altogether, the rivers may
reach the sea by many mouths without the formation of barriers,
or, in other words, may form true deltas. The height of the tide
of the Mexican Gulf along the north shore is but twelve to fifteen
inches; and, consequently, while most of the streams, before even
this small tide, have their bars and barriers, the great Mississippi
sends its many arms far out into the Gulf, prolonging its channels in
the face of winds, waves, and tide (fig. 942, p. G4G). Incipient sand¬
bars at times form; but these serve only to divide one of the great
channels, and make a new branch.
The course of the out-flowing currents during ebb tide, in con¬
junction and alternation with the in-flowing tidal current and waves,
determines the position of the channels and sand-bars, and causes
the prolongation of hooks off prominent capes. In some cases,
wind-currents are concerned in the action. The general process is
the same as when only the currents of the ebb and flow are con¬
cerned; but the ebb tide has far greater effect from the added
volume, velocity, and detrital material of the river. The out-flowing
currents are deep and strong, sweeping out the channels of bays and
lagoons, and moulding the sand bars and spits ; while the in-flowing
move in a more diffused manner, and with much less rapidity and
664
DYNAMICAL GEOLOGY.
effect. Prof. Bachehas thus explained the increase of Sandy Hook
(the southern cape at the entrance of New York Bay). Ilis obser¬
vations prove that the current during ebb tide is most effectual in
prolonging and shaping the Hook, though the in-flowing tide con¬
tributes to the result, and the waves aid in giving the hook-like form
by bending in the extremity. The Hook has been elongated at the
rate of " one-sixteenth of a mile in twelve yeai's," since the time
when the first precise observations were made.
3. Structure of the formations.
Beach-formations are irregularly stratified, the layers being much
interrupted, and varying every few rods or less, as represented in
fig. G1 d, p. 93. The layers are either of sand, gravel, pebbles, or
stones. In the lower part, where washed by the tides, they often
slope seaward a few degrees. Over the area of shallow waters out¬
side, the deposits in progress consist mostly of fine detritus, either
sandy or argillaceous, with rarely pebbles, except near the beach;
and through the greater part argillaceous beds prevail, as shown
by soundings. The beds may be uniform over very large surfaces.
These regions are fifty to eighty miles wide on the eastern border
of North America (fig. GG4, p. 441). In the lagoons or bays, argil¬
laceous deposits are the most extensive; but sand and pebbles may
be distributed among them, especially off the mouths of streams.
As stated on page 612, the material of the bottom of the submerged plateau,
above referred to, outside of a depth of 90 feet, consists at surface one-half of
Rhizopod shells. Off southern New England, at depths between 300 and 550
feet, from a region southeast of Montauk Point to that southeast of Capo Hen-
lopen, the soundings, according to Bailey, consist chief )) of these shells. At
greater depths, beyond the limit of the plateau, Pourtales found almost a pure
floor of Rliizopods. The species are deep-water species, differing thus from
those of the New Jersey Cretaceous beds. Pourtales observes, in a recent letter
to Professor Bache (dated May 17, 1802), that along the plateau between the
mouth of the Mississippi and Key West, for two hundred and fifty miles from
the mouth, the bottom consists of clay, with some sand and but few Rhizopods;
but beyond this the soundings brought up either Rhizopod shells alone, or these
mixed with coral sand, Nullipores, and other calcareous organisms.
As microscopic life abounds in harbors where rivers make frequent depositions
of sediment, the presence of a considerable proportion of Rhizopods is consistent
with an annual increase of the plateau from sedimentary depositions. (Bailey,
Smithsonian Contrib. ii.; Amer. Jour. Sci. [2] xvii. 176, and xxii. 282; Pourtales,
Trans. Amer. Assoc., Charleston meeting, 1850, 81; Reports Coast Survey for
1853, p. 83, and 1858, p. 248.)
Ripple-marks are often made by the waves over the finer beach-
sands, where they are low and partly sheltered, and also over mud¬
flats. The flowing water pushes up the sand into a ridgelet, as high
THE OCEAN.
665
as the force can make, and then plunges over the little elevation and
begins another; and thus the succession is produced. The height
and breadth of the intervening space will depend on the force and
velocity of the flowing water, and the ease with which the sand or
mud is moved. Ripple-marks may be made by the vibration of
waves even at depths of 300- to 500 feet.
The rapid in-flowing tidal or other current over the sands of sand¬
bars, and the bottoms of bays, may produce an effect similar in
general character to ripples, although on too large a scale to be re¬
cognized as such. The oblique lamination of layers, represented in fig.
61 c, p. 93, is probably a result in this way of a pushing action in
waves or currents.
When a wave dies out on a beach, it sometimes leaves a tracing
of its sweep on the sand, as a wave-line; and the returning waters
flowing by any half-buried shell or stone may make rills in the
sand, or rill-marks (fig. 63, p. 94).
Broken shells, and other marine relics in fragments, are common
in beach-deposits. Below high-tide level, there may be the vertical
borings of sea-worms, of certain Crustaceans (as species of the Callia-
nassa family), and some Mollusks. In the off-shore shallow waters
occur beds of living Mollusks, and other kinds of animals, as well as
plants, varying according to the depth.
4. Action of the oceanic ivaters over a submerged Continent, and during a gra¬
dual submergence or elevation.
1. Marine deposits.—The most obvious effect of the slow submer¬
gence of a continent beneath the waters of the ocean would be the
working-over, by the waves and marine currents, of the loose earth,
gravel, and alluvium of the surface, thereby changing them into
marine deposits. The depth to which this alteration would extend
would, for the most part, be much less, probably, than a hundred
feet. Whatever the extent, the ocean, besides exterminating living
species, would obliterate most of the remains of terrestrial life in
the altered deposits, and introduce its own living Mollusks and
other tribes throughout the new continental seas.
2. Features of the surface not altered by an excavation of valleys, but by a
diminution of its heights and a filling of pre-existing valleys.
It might be supposed, at first thought, that the ocean would wash
through the valleys with great excavating force, and make deep
gorges over the surface. The real effect will be best learned from
the present action on sea-coasts; for with every foot of submer¬
gence the sea-beach would be set a little farther inland, so that
the whole would successively pass through the conditions of a sea-
CG6
DYNAMICAL GEOLOGY.
shore. On existing sea-shores the action in progress, instead of
tending to excavate valleys, produces just the contrary effect, it is
everywhere wearing off exposed headlands, and filling up bays.
The salt waters, in fact, enter but a short distance the river-valleys
of a coast, because they are excluded by the out-flowing stream.
The bottom of the Hudson is below the sea-level for a long distance
beyond the limit to which the pure ocean-water extends: the same
is true of the St. Lawrence, and of many other rivers along the
coast. During a progressing submergence, therefore, the ocean
would have no power of excavating narrow valleys, unless they
happened to be open at both ends, so as to allow the oceanic cur¬
rents to sweep through.
As the submergence progressed, there would be, through wave-
action, extensive degradation of the ridges and mountains over the
surface, and a distribution of the detritus through the intervening
depressions. In a subsequent emergence of the land, the moun¬
tains and ridges would be still further degraded, and the valleys
filled by their debris. The laws of sea-coast action would again
come into play, and the wear of all new headlands, and the filling
of bays, continue to be the result, as long as the emergence was in
progress.
3. Effects as to tlieformation of marine deposits when a continent is mostly
without mountain-ranges and valleys.
If the continent were to a large extent without mountains, the
broad fiat surface might then lie slightly above or below tide-level
at once, or nearly simultaneously, so that under a small change of
level the waves could sweep across the whole area. It has been
shown that the Appalachian Mountains were not raised until after
the Carboniferous age, and the greater part of the Rocky Moun¬
tains not before the close of the Cretaceous period. The North
American continent was, therefore, in early time, in the condition
here supposed; and the older formations have a corresponding
extent and character. There were continental oscillations, causing
slight emergences of large areas to alternate with varying sub¬
mergences, and through such changes the variations in the forma¬
tions were produced, differences of depths causing transitions from
arenaceous to argillaceous or to pebbly and conglomeritic accumu¬
lations ; and the differences required for such changes are so small
that the probability of finding the cotemporaneous fragmental depo¬
sits of Europe and America, or even of distant parts of one con¬
tinent, alike arenaceous, argillaceous, or conglomeritic, is exceed¬
ingly small. The details of the history as regards North America
have already been given, and need not be here repeated.
GLACIERS.
667
3. FREEZING AND FROZEN WATER.
Water performs part of its geological work in the act of freezing,
and another part when frozen, in the condition of snow and ice.
1. WATER FREEZING.
Rending and disintegration from expansion.—As water in freezing ex¬
pands on reaching 39}° F., the freezing-process in the seams of
rocks opens those seams, tears rocks asunder, and tumbles fragments
and masses down precipices ; or in porous strata it crumbles off
the surface, and causes disintegration. Consequently, bluffs in a
cold climate, like the trap hills of Connecticut and the highlands
of the Hudson, have a long talus of broken stone made mainly by
this means,—while in a tropical climate the precipices are generally
free from fragments. This cause of degradation goes on incessantly
in all icy regions where there are melting and freezing, and may have
originated much of the soil and drift of the globe.
2. ICE OF RIVERS AND LAKES.
Ice forming along streams in which there are stones envelops
the stones in shallow water, even to a depth of two or three feet, or
more in the colder climates. Other stones and earth fall on the ice
from the banks. When the floods of spring raise the stream and
break up the ice, both ice,and stones,often float down stream with
the current, or are drifted up the banks high above their former
level, or are spread over the river-flats.
Ice sometimes forms about stones in the bottom of rivers when
the rest of the water is not frozen, and is then called anchor-ice. In
this condition, it may serve as a float to raise the stones and to
transport them with the aid of the current.
The same modes of transportation are exemplified in lakes as in
rivers, except that there is less current, and the stones are mostly
set back up the shore. Large accumulations of stray stones far
above the ordinary level of the lake are in some places thus made.
3. GLACIERS.
1. General features, formation, and movement of Glaciers.
1. Nature of Glaciers.—Glaciers are accumulations of ice descend¬
ing by gravity along valleys from snow-covered elevations. They
are ice-streams, 200 to 5000 feet deep or more, fed by the snows and
6G8
dynamical geology.
frozen mist of regions above the limits of perpetual frost. They
stretch on 5309 to /5C0 feet below the snow-line (limit of perpetual
snow), because they are so thick masses of ice that the heat of the
summer season is not sufficient to melt them. Some of them reach
down between green hills and blooming banks into open culti¬
vated valleys. The extremities of the glaciers of the Grindelwald
and Chamouni valleys lie within a few hundred feet of the gardens
and houses of the inhabitants. Each glacier is the source of a
stream, made from the melting ice. The stream begins, high in the
mountains, from the waters that descend through the crevasses to
the ground beneath, and often makes a tunnel in the ice above its
course; finally it gushes forth from its cavernous crystal recesses a
full torrent, and hurries along over its stony bed down the valley.
2. Glacier regions.—The best known of glacier regions is that of
the Alps. The chain west of the head-waters of the Rhone is
divided into two nearly parallel ranges, a southern and a northern.
The latter includes, besides minor areas, two large glacier districts,
-—the Mt. Blanc and the Mt. Rosa or Zermatt district; and the
former, one of equal extent, though its peaks are less elevated,—
that of the Bernese Oberland. There is another district of glaciers
at the head-waters of the Rhone, and others farther eastward.
Glaciers occur also in the Pyrenees, the mountains of Norway,
Spitsbergen, Iceland, the Caucasus, the Himalayas, the southern
extremity of the Andes, in Greenland, and on Antarctic lands.
One of the Spitzbergen glaciers stretches eleven miles along the
coast, and projects in icy cliffs 100 to 400 feet high. The great
Humboldt glacier of Greenland, north of 70° 20/, has a breadth at
foot, where it enters the sea, of forty-five miles ; and this is but one
among many about that icy land.
3. Many Glaciers from one Glacier district.—The following map (fig.
943) represents the Mt. Blanc glacier region, excepting a small part
at its southwestern extremity. The vale of Chamouni along the
river Arve bounds it on the northwest, and .the valley of the river
Doiro on the southeast. This mountainous area, though one vast
field of snow, gives origin to numerous glaciers on its different sides,
■—each principal valley having its ice-stream. The series of dotted
curves show the courses of the several glaciers. B is Mt. Blanc;
bs, the Glacier des Bois, or Bois Glacier (so named from a village
near the foot of the glacier); m, the Mcr dc Glace, an upper portion
of this glacier. The river Arvciron issues from the extremity of
the glacier, and, after a short course, joins the Arve near the village
of Chamouni. The Geant {g), Talefre (ta), and Lcchaud (I) glaciers
are the three largest of the upper glaciers which combine to form
GLACIERS.
669
Figs. 9 4 R-952.
Fig. 948.—Part of the glacier district of Mt. Blanc, the lighter middle portion of the map
16 miles long, ont of 22 miles the whole length; river on the northwest side, the Arve
in the valley of Chamouni, and that on the southeast side, the Doire; B, Mt. Blanc; G,
Aiguille du Geant; J, the Jardin; T, Aig. du Tour; V, Aig. Verte; a, Argcntiere Glacier;
ba, Brenva Gl.; bn, BossonsGl.; bs, Bois Gl.; g, Geant or Taeul Gl.; I, Lecliaud Gl.; m,
Mer de Glace, upper part of the Bois Glacier; mg, Miage Gl.; la, Tal&fre Gl.; tr, Tour
Gl.; tt, Trient Gl.
Fig. 949.—Section of the Mer de Glace near m of fig. 94R, or opposite Trelaporte; 950,
section of same near bs of fig. 948, or oppositeMontanvert; 951, View of the PihoueGlacier;
952, profile of same, c, c, etc. being the transverse crevasses, fading out, and becoming
curved after passing the cascade at am.
GTO
DYNAMICAL GEOLOGY.
the Mer de Glace. In fig. 949, the hands correspond to different
tributaries of this glacier, and the broadest one to the right is that
of the Geant Glacier.
4. General appearance.—Fig. 953 is a reduced copy of a sketch in
Agassiz's great work, representing the Glacier of Zermatt, or the
Gorner Glacier, in the Mt. Rosa region. This grand glacier receives
Fig. 953.
Glacier of Zermatt, cr the Gorner Glacier.
some of its tributaries from the right, but the larger part beyond
the Riffelhorn, the near summit on the left. The dark bands on
the glacier are lines of stones and earth, called moraines. The lon¬
gitudinal lines on fig. 949 represent moraines on the Mer de Glace.
The ice of a glacier is intersected by fractures or crevasses made by
its movement through the irregular valley.
Glaciers descend slopes of all angles. There are cataracts and
cascades among them as well as among rivers. One of the large
tributaries of the Mer de Glace, the Glacier du Geant [g, fig. 948),
descends in an immense ice-cascade from the plateau of the Col
du Geant into the valley below. The Glacier of the Rhone—one
GLACIERS.
671
of the grandest in the Alps—is another ice-cataract. As the glacier
commences its steep descent, it becomes broken across, and thus
great sections of it plunge on in succession, separated partly by
profound transverse chasms. Fig. 951 gives the outline of the lower
part of the glacier, am being the cataract, mb its terminal portion
or foot, from the extremity of which the river Khone issues, and
c, c, c, transverse crevasses of the cascade. The same is shown in
profile in fig. 952, in which c, c, etc. are the transverse crevasses.
Other glaciers in some of the higher valleys of the Alps reach
the edge of a precipice to descend, perhaps thousands of feet, in a
crashing avalanche, in which the ice is broken to fragments.
5. Formation of Glaciers.—The uppermost portion of a glacier con¬
sists of snow and frozen mist, deposited in successive portions, and
usually more or less distinctly stratified. This part is called the
neve. At a lower limit, the snow becomes compacted by pressure
into ice, owing to the depth of the accumulations ; and here the
true glacier portion begins. Below the limit of perpetual frost
there is occasional melting in summer, with alternate freezing; and
this process aids in changing the mass, as well as the surface-snow,
to ice. The stratification of the neve is not generally distinct in
the icy glacier.
The following circumstances are essential to, or influence, the formation
of glaciers.
(1.) There must be an elevation, or range of heights, above the
line of perpetual congelation.
(2.) Abundant moisture is as important as for rivers ; and hence
one side of a chain of mountains may have glaciers, and not the
opposite.
(3.) A difference of temperature between summer and winter is
requisite ; for otherwise the snows will be melted to the same line
throughout the year, and will not descend much below the line of
perpetual congelation.
The level of perpetual congelation, and the distance to which
glaciers descend, depend on the mean temperature and moisture of
the region, and especially the mean temperature of summer as
contrasted with that of winter. The height of the snow-line, or
that of perpetual congelation, is that in which 32° F. is the summer
temperature. Below this runs the year-line of 32° F., along which
32° is the mean annual temperature. Still below this lies the glacier-
limit,—that is, the lowest limit of the glacier. At Mont Blanc, the
snow-line is 2000 feet above the 32° year-line, and the glacier-limit is
4500 to 5300 feet below it, or 9000 feet above the sea. In the Pyrenees,
the snow-line is also 2000 feet above that of 32°; in the Caucasus,
672
DYNAMICAL GEOLOGY.
2500 feet; in some parts of the Arctic, 3500 feet; on the south side of
the Himalayas, 2000 feet, and on the north, 2600; while in the equable
climate at the equator in the Andes, the snow-line is 1000 feet below
the year-line of 32°. In Norway, the glacier-limit is 4000 feet below
the line of 32°.
The lower limit of a glacier sometimes varies several miles in the
course of a series of years. A succession of moist years increases
the thickness of the glacier, and thereby its tendency downward;
while dry years have the reverse effect. If the moist years have
also long, hot summers, the descent and lengthening of the glacier
will be further promoted,—since glaciers move most rapidly in
summer. But hot, dry years would shorten it, by diminishing the
ice, and especially at the lower end.
Lowering the mean temperature of a place by cooling the summers would
lower the glacier-limit. Great Britain and Fuegia arc in nearly the same, lati¬
tude ; and yet in Fuegia the snow-line is only ,1000 fec:t above the sea. If, by
any means, the climate of Great Britain could he reduced to that of Fuegia, it
would cover the Welsh and Irish mountains with glaciers that would reach
the sea, the snow-line being hut 1000 to 2000 feet above it; and the same
cause would place the snow-line in the Alps at 5000 to 0000 feet above the sea,
instead of 9000. This change of temperature involves a removal of tropical
sources of heat, or an increase of arctic sources of cold. The diversion of the
Gulf Stream by the submergence of Daricn lias been thought of as a means for
the former; but it unfortunately leaves the winds blowing in their old direction,
and these cannot be so easily managed. An increase of arctic lands by such
elevations as have taken place in former times would accomplish the latter.
6. The laio, rate, and method of flow.—The law of flow is essentially
that of rivers. There is friction along the bottom and sides of the
glacier, and cohesion in the ice adjoining. The flow is, consequently,
most rapid at the surface ; and the axis of greatest velocity varies
from the medial line to one side or the other of it, according to the
bends in the course of the valley. The motion is so slow that there
is no atmospheric friction to retard the surface-movement. The
greater rapidity of the middle portion is shown by the fact that the
transverse ridges made at an ice-cascade, like that of the Bhone,
and the lines of earth and sand in the chasms, become afterwards
arched in front, as shown in fig. 951, in which the crevasses c are at
first transverse, but curve below the cascade. The arch is sometimes
very much elongated, almost to a triangular form, as in the Geant
portion of the Mer de Glace. This is well illustrated in figs. 949,
950, from Tyndall: the right-hand half of the figure corresponding
to the Geant Glacier (the cascade in which is alluded to on p. 670)
has the transverse bands (carrying dirt and stones) elongated
into triangles, while in the other half of the Mer de Glace there
GLACIERS.
673
»re no such bands, as the tributaries making it do not descend in
cascades. (Tyndall.) This difference of velocity between the middle
and sides of a glacier has been proved also by direct experiment.
The rate of movement depends, upon the slope and mass. Accord¬
ing to different observations, it varies from five to over fifty inches
a day; and in some places a glacier may be so embayed as to lie
almost without motion. A rate of eight to ten inches a day is most
common: it is equivalent to 243£ to 304 feet a year, or one mile in
about twenty-two to seventeen years.
Forbes deduced, from bis measurements made at two stations on each of the
Bois and Bossons Glaciers, the following results. The first station on the Bois
Glacier was near its upper part, where the rapidity is unusually great, and the
other near its lower extremity.
Boss. II.
Bois I.
Bois II.
Boss.
I.
Motion from Nov. '44 to Nov. '45..
847.5 ft.
220.8 ft.
657.8
ft.
Mean daily motion
27.8 in.
7.3 in.
21.6
in.
Mean daily motion in summer,
April to October
37.7 in.
9.9 in.
28.0
in.
Mean daily motion in winter, Oc¬
tober to April
19.1 in.
4.7 in.
CO
in.
489.1 ft.
16.1 in.
22.2 in.
10.7 in.
This table shows, further, that the rate of motion is about twice as great in
summer as in winter.
The maximum in July at the upper station on the Bois Glacier was 52.1
feiches; in December, 11.5 inches. The rapidity at the same place is not always
the same in different years. Thus, at one station on the Mer de Glace, Forbes
obtained for the daily motion in 1842-43, 1843-44, 1844-46, the amounts 8.56,
9.47, 10.65 inches. A knapsack lost in the Talefre Glacier (t, in fig. 948) after
ten years was found 4300 feet distant the slope here of this high glacier was
14° 55' (Forbes).
The rate (1) at the upper surface, (2) half-way to the bottom, and (3) at the
bottom, was found by Tyndall to be in one case 6 inches, 4.59 inches, and 2.56
inches, in a day; and the rapidity at the middle above, to be one-half faster
than along the sides.
The power of motion in a glacier is attributed to—
(1.) The capability it has, to a limited extent, of sliding along its
bed, but only portions at a time.
(2.) A degree of plasticity, or, at least, flexibility, in ice. A heavy
oblong mass supported at one end may be bent even into a short
arch by its own weight. Kane mentions in his "Arctic Explo¬
rations" the case of one table of ice, eight feet thick and twenty
or more wide, supported only at the sides, which, between the
middle of the months of March and May, became so deeply bent
that the centre was depressed five feet. The temperature during
the interval was at all times many degrees below the freezing-point.
44
674
DYNAMICAL GEOLOGY.
This property of ice may be one means by which a glacier adapts
itself to the uneven slopes of a valley. It is questioned whether
it is not dependent on the following.
(3.) The facility with which ice breaks and mends its fractures
by regelation; that is, by a freezing together again of the surfaces
that are in contact. This principle, first applied to glaciers by
Tyndall, is the one of prominent importance. Any one may test
it by breaking a piece of ice and then putting the parts together
again : the surfaces, if moist, will become firmly united. A glacier
moves on, breaking and mending itself through its whole course.
The multitudes of fractures made on steep slopes may all disappear
below when the motion becomes slow and the ice feels the pressure
from above.
Along the sides of a glacier, especially when passing prominent
angles in the valley, the crevasses are deep and numerous. The
ordinary direction of these crevasses is obliquely up stream, or at
an angle of forty to fifty degrees with the margin, being at right
angles, nearly, to the lines of greatest tension in the descending
glacier. The crevasses at a bend form especially on the convex
side of the stream, the ice undergoing a stretching on that side and
a compression on the opposite. There are also deep transverse
crevasses, and others of irregular courses, made when a glacier is
forcing its way through narrow passes in a valley, and when descend¬
ing rapid slopes. Afterward, on reaching a border-portion of the
valley, the ice may return to a solid mass with a comparatively
even surface, having fractures only towards the sides. Forbes
mentions one chasm 500 feet wide extending quite across the Mer
de Glace.
7. Structure induced by the movement of a glacier.—The ice of a glacier
is often vertically laminated parallel to its sides, and sometimes so
delicately so that the ice appears like a semi-transparent striped
marble or agate. The layers are alternations of cellular (or snowy)
ice and clear bluish solid ice. The melting of the surface some¬
times leaves the more solid layers projecting.
The structure is due, as shown by Tyndall, to the pressure to which
the glacier is subjected in making its way between the walls of a
valley, especially where there is a contraction in width, or a pro¬
jecting point against which pressure is exerted, and particularly
below a place of steep descent. It may be formed when two great
glaciers unite, the pressure between the meeting streams being
here the cause.
The resistance to motion in a glacier is not continuously over¬
come, as in the case of a perfect fluid, but intermittently. This
GLACIERS.
675
is evinced in the successive transverse crevasses of a cascade-glacier
like that of the Rhone, or in the dirt-bancls which are registers of
the successive crevassing. Each movement, moreover, must cause
a series of vibrations, of great force, in the ice. Such intermittent
and oscillatory action is especially calculated to produce a laminated
structure. As Tyndall has observed, the air-cells appear to have
been in part expelled from the bluish layers by the pressure, and in
part to have been obliterated by an incipient liquefaction and re-
freezing of the layer.
In the lower part of the glacier of the Rhone, the laminated
structure is produced, according to Tyndall, between the capes m
and n (fig. 951),—the structure-mill, in his language. It appears first in
the section s, and is fully developed in the following one, s/. The
radiating lines in the view represent crevasses.
This lamination is very distinct over parts of most glaciers. It
is well shown either side of the middle of the Mer de Glace; it
gives a longitudinal structure to the central portions of the Aar
Glacier below the junction of its two great branches, the Finster-Aar
and the Lauter-Aar ; it characterizes, according to Forbes, the whole
of the Brenva Glacier.
2. Transportation and erosion.
1. Transportation.—The moraines of glaciers are made from (1) the
stones and earth which fall from the cliffs along their borders ;
(2) the material received from falling avalanches; (3) that which
is taken up by the ice from the surface of the valley against which
they move. They form in all the stages of progress of a glacier,
though usually the least in the region of the neve, where the peaks
are often small compared with the extent of snow. The surface in
this upper part is always peculiarly white and clean, owing to the
frequent falls of snow.
From their mode of origin, it follows that moraines are situated
primarily along the margin of a glacier. But, when two glaciers
coalesce, the two uniting sides join their moraines in one; and this
one is remote from the borders, and may be central—as in the glacier
of the Aar—if the two coalescing streams are about equal. It fol¬
lows from the above that the number of moraines on a glacier can
never exceed the number of coalesced glaciers by more than one.
In the Glacier of Zermatt, the nearest moraine in the view (fig.
953) is that of the Riffelhorn ; the second is a union of moraines of
the Gornerliorn and Porte Blanche ; the third, a union of two mo¬
raines from two Mt. Rosa Glaciers ; the fourth, the great moraine of
the Breithorn, the summit in the middle of the view. Other
676
DYNAMICAL GEOLOGY.
moraines may be seen on the distant part of the glacier. In fig.
949, representing a section of the Bois Glacier near Trelaporte,
there are six distinct moraines.
Toward the lower extremity of a glacier (as shown in fig. 950,
from the lower part of the Bois Glacier) the several moraines usually
lose their distinctness through the melting of the ice; for this brings
the stones and earth that were distributed at different depths to
one level, and thus produces a coalescence of the whole over the
surface.
The stones are both angular and rounded, the former far the
more abundant. Many are of great magnitude. One is men¬
tioned containing over 200,000 cubic feet, or equal in size to a build¬
ing 100 feet long, 50 wide, and 40 high.
At the glacier of the Aar, the central moraine is raised 100 to 140
feet above the general surface either side ; but this is partly owing
to the pressing up of the ice itself by the mutual pushing of the
two combined glaciers of which it is made. The breadth where
narrowest is 250 feet; and from this it increases to 750 feet half¬
way to the termination of the glacier, and to treble this below.
The final melting of a glacier leaves vast piles of unstratified
stones and earth along its sides, toward and about its lower ex¬
tremity. The stream which proceeds from the glacier works over
all that comes within its reach, carrying it onward down the valley,
and making deposits on its banks which are usually more or less
perfectly stratified.
2. Erosion.—(1.) The movement of a glacier is attended with so
much wrenching of the ice, that the blocks generally have their
angles more or less blunted by mutual attrition, and many of the
stones are rounded.
(2.) As the glacier has its sides and bottom here and there set
with stones of large and small size, it is a tool of vast power as
well as magnitude, scratching, ploughing, and planing the rocks
against or over which it moves. Besides this, it pushes along gravel
and stones between itself and the rocks, with the same kind of
effect. The rocky cliffs and ledges in the vicinity of the glaciers
are in many places furrowed, planed, and rounded over their whole
exposed surface from this agency. The furrowings or gougings
have a common direction; but there are sometimes two or more
directions, indicating glacier-movements of different periods.
(3.) The stones which have produced the furrowing are some¬
times scratched themselves.
Other facts connected with this subject are mentioned on page
535. See also the works of Agassiz, Forbes, and Tyndall.
ICEBERGS.
677
Glaciers, as these facts show, are also powerful agents in widening
and deepening valleys.
The snow and ice of Alpine valleys often cause, indirectly, violent
erosion and transportation of material by damming up streams.
In no other way can barriers be thrown so readily across profound
valleys; and the deluges caused by the accumulated waters when
they break loose are often very destructive. The Alps are full of
examples.
4. ICEBERGS.
A glacier on a sea-coast often stretches out its icy foot into the
ocean, and when this part is finally broken off' by the movement
of the sea, or otherwise, it becomes an iceberg. Greenland is the
great region of icebergs, no less than of glaciers. They carry away
the stones and earth with which the glacier was covered during
its land-progress, and transport them often to distant regions,
whither they are borne by the polar oceanic currents.
Dr. Kane describes the great pack of icebergs that occupies the
centre of Baffin's Bay, and mentions that some were 300 feet high,
and large numbers over 200 feet. There were 280 icebergs of the
first magnitude (the most of them over 250 feet) in sight at one
time.
In the Antarctic, Captain Wilkes observed a long ice barrier,
having a height above the sea of 150 to 200 feet; and some of the
bergs were 300 feet high. The ice of the barrier was stratified; and,
according to Wilkes, this was owing to the constant increase from
the freezing mists over it.
As the specific gravity of ice is 0.918 (at 32° F.), the proportion
of the mass out of water is about one-twelfth.
The icebergs of the Atlantic melt mostly about the Banks of
Newfoundland, or between the meridians of 44° and 52°. They
have been observed in this ocean as far south as 30° 10/.
Icebergs are (1) a means of transporting stones and earth from
one region to another (see p. 542). (2.) When grounded on rocks
they may scratch the surface; but closely-crowded and regular
scratches like those of glaciers over large areas could hardly be
made. The currents of Baffin's Bay flow southward on the west
side and northward on the other,—which would give great irre¬
gularity there to the scratches of grounded bergs. An iceberg
"rocked by the swell of the sea, and sometimes turning over,"
could not be good at scoring submerged rocks. Moreover, these
rocks, in the seas in which icebergs melt and drop their freight of
stones, would seldom be uncovered.
678
DYNAMICAL GEOLOGY.
4. FORMATION OF SEDIMENTARY STRATA.
In recapitulation, sedimentary strata have been formed—
1. By the waters of the sea.
(1.) Through the sweep of the ocean over the continents when
harely or partly submerged,—making (a) sandy or pebbly deposits near
or at the surface where the waves strike, or at very shallow depths
where swept by a strong current; (b) argillaceous or shaly deposits
near or at the surface, where sheltered from the waves, and also
at considerable depths out of material washed off the land by the
waves or currents; (e) but not making coarse sandy or pebbly de¬
posits over the deep bed of the ocean, as even great rivers carry
only silt to the sea; and not making argillaceous deposits over the
ocean's bed except along the borders of the land, unless by the aid
of a river like the Amazon, in which case, still, the detritus is
mostly thrown back on the coast by the waves and currents.
(2.) Through the waves and currents of the ocean acting on the
borders of the continent with the same results as above, except that
the beds have less extent.
(3.) Through living species, mainly Mollusks, Radiates, and Rhi-
zopods, affording calcareous material, and Diatoms and some Proto¬
zoans, siliceous material. All rocks made of corals and the shells
of Mollusks, excepting the smallest, require the help of the waves
at least to fill up the interstices (see p. 619); but Rhizopods and
siliceous Diatoms may make rocks in deep water, by accumulation,
which are in no sense sedimentary.
2. By the waters of lakes.—Lacustrine deposits are essentially like
those of the ocean in mode of origin, unless the lakes are small,
when they are like those of rivers.
3. By the running waters of the land.—(1.) Filling the valleys with
alluvium, and moving the earth from the hills over the plains.
(2.) Carrying detritus to the sea or to lakes, to make, in conjunc¬
tion with the action of the sea or lake waters, delta and other
sea-shore accumulations.
4. By frozen waters.—(1.) Spreading the rocks and earth of the
higher lands over the lower, and, in the process, bearing on blocks
of great size, such as cannot be moved by other means. (2.) Carry¬
ing rocks and earth from the land to the ocean, either to the
sea-shore, making accumulations in lines or moraines, or to distant
parts of the ocean, as from the Arctic to the Newfoundland Banks;
and thus contributing to deep or shallow water or shore sediment¬
ary accumulations, distinguished by the irregular intermingling ol
huge blocks of stone, pebbles, and earth.
EXTENT AND TOPOGRAPHICAL EFFECTS OF EROSION. 679
5. EXTENT AND TOPOGRAPHICAL EFFECTS OF
EROSION OYER THE CONTINENTS.
1. Extent of erosion.—The outlining of mountain-ridges and
valleys has been in part produced by subterranean forces frac¬
turing the strata; but the final shaping of the heights is due to
erosion. This cause has been in action from the earliest time, and
nearly all rocks not calcareous have resulted from the erosion of
pre-existing formations. The Appalachians have probably lost by
denudation more material than they now contain. Mention has
been made of faults of even twenty thousand feet along the
course of the chain from Canada to Alabama. In such a fault one
side is left standing twenty thousand feet above the other, equi¬
valent in height to some of the loftier mountains of the globe;
and yet now the whole is so levelled off that there is no evidence
of the fault in the surface-features of the country. The whole
Appalachian region consists of ridges of strata isolated by long
distances from others with which they were once continuous.
Fig. 103 represents a common case of this kind. It is supposed
by some geologists that the Appalachian and western coal-fields
were once united, and that, in western Ohio and other parts of the
intermediate region, strata thousands of feet deep, from the Lower
Silurian upward, have been removed, and this over a surface
many scores of thousands of square miles in area. This view has
been questioned on a former page. Whether true or not, there is
no doubt that the anthracite coal-fields of central Pennsylvania
were once a part of the great bituminous coal-field of western
Pennsylvania and Virginia (fig. 559, p. 323). They now form iso¬
lated patches, and formations of great extent have been removed
over the intervening country. The Illinois coal-region is broken
into many patches in consequence of similar denudation and
uplifts.
In New England there is evidence of erosion on a scale of vast
magnitude since the crystallization of its rocks. On the summit-
level between the head-waters of the Merrimac and Connecticut,
there are several pot-holes in hard granite; one, as described by
Professor Hubbard, is ten feet deep and eight feet in diameter,
and another twelve feet deep. They indicate the flow of a
torrent for a long age where now it is impossible ; and the period
may not be earlier than the Post-tertiary. Many other similar
cases are described by Hitchcock.
These examples of denudation are sufficient for illustration.
680
DYNAMICAL GEOLOGY.
Europe and the other continents furnish others no less remarkable,
and to an indefinite extent.
2. Topographical effects of erosion.—The topographical effects
of erosion depend on several conditions,—as (1) the durability of
the rocks, (2) their structure, and (3) their stratification.
1. Durability of the roclcs.—Granite is well known to runup into lofty needles
(or aiguilles), as in the Alps and, still better, the Organ Mountains of Brazil and
some peaks in the Shasta Mountains of California. But there are varieties
crumbling easily on exposure, and these occur only in broad, massive eleva¬
tions. The hard argillite (roofing-slate) often forms bold, craggy heights, while
soft argillaceous shales make only tame hills and undulating plains.
The refractory quartzites and grits, which make little or no soil, stand up in
rude piles and massy brows of nearly bare rock.
2. Structure.—When there are no planes of structure, as in true granite, the
rock may rise into lofty peaks with rounded surfaces. Slow denudation goes
on over all sides of the peak, either from trickling waters or frosts, and may
gradually narrow it into the model aiguille. But when the rock has a cleav¬
age-structure like the schists and slates, its heights are rough and angular,
and its aiguilles, if any are formed, are more apt to be pyramidal than conical.
The joints in slates or sandstones often lead to forms resembling walls and
battlements when exposed in cliffs (fig. 88, p. 100). The architectural effect of
the columnar cleavages of trap or basalt is shown in fig. 115, p. 118.
3. Stratification.—The results with stratified rocks differ according to (1)
the position of the strata, and (2) their nature.
If the strata are horizontal, or nearly so, and hard and similarly so through¬
out, the elevations have generally table summits, with vertical rocky brows
facing the lower lands. The river-valleys are profound, and often inaccessi¬
ble for long distances, owing to the boldness of the precipices. Some varieties
of these valleys are shown in figs. 940, 941. Other topographical effects are
described in the remarks on the erosion of valleys, p. 635. If the rock is
firm, like most limestones, it may rise into lofty, few-angled summits, espe¬
cially when erosion has been preceded by fractures; as in the Alpine heights
of the Wetterhorn and its associates near Grindelwald, in the Bernese Oberland.
If horizontal, or nearly so, but of unequal hardness, the softer strata are
easily worn away, undermining the harder strata; the table-lands have a top
of the harder rock, and the declivities are usually banded with projecting
shelves and intervening slopes. Figs. 954, 955 represent the common cha¬
racter of such hills. A number are shown in fig. 940; in the Colorado region
they have been called Mesas, from the Spanish for table;*
* For figures 954-965 and the views they illustrate, the author is indebted
to the volume on " Coal and its Topography," by Lesley. In a long chapter,
on " Topography as a science," this author has given the results of extensive
personal observation.
Fig. 954.
Fig. 955.
HEAT.
681
When the beds are inclined between 5° and 30°, and are alike in hardness,
there is a tendency to make hills with a long back slope and bold front; but
with a much larger dip, the rocks, if hard, often outcrop in naked ledges.
When the dipping strata are of unequal hardness, and lie in folds, there is
a wide diversity in the results on the features of elevation.
Figs. 956, 957 represent the effects from the erosion of a synclinal elevation
consisting of alternations of hard and soft strata. The protection of the
Figs. 956-961.
softer beds by the harder is well shown. This is still further exhibited in
figs. 958-961.
Anticlinal strata give rise to another series of forms, in part the reverse of
the preceding, and equally varied. Figs. 962-965 represent some of the sim¬
pler cases. When the back of an anticlinal mountain is divided (as in figs.
962, 963, 964), the mountain loses the anticlinal feature, and the parts are
Figs. 962-965.
1! Ill 1164
WTtTY!
1il//l M 65
simply monoclinal ridges. In fig. 965, the anticlinal character is distinct in
the central portion, while lost in the parts either side. In fig. 965 to the
right, a common effect is shown of the protection afforded to softer layers by
even a vertical layer of hard rock : the vertical layer forms the axis of a low
ridge.
The above are the simple results from the erosion of folded rocks. They
serve as a key to the complexities of features common through a large part
of the Appalachians, where synclinal and anticlinal axes, as Lesley states, are
in numberless complicated combinations, and are rendered doubly puzzling
by faults. See, further, pages 104-109. 404-408.
Y. HEAT.
1. SOURCES OF HEAT.
The crust of the Earth has three sources of heat:—(1) The Sun ;
(2) Chemical and mechanical action ; (3) The igneous condition
of the Earth's interior.
082
DYNAMICAL GEOLOGY.
L The Sun.—The Sun (1) causes, and must always have caused,
an increase of temperature over the globe from the poles to the
equator, as well as a variation of seasons. (2.) In the warmer
season it heats the soil to a varying depth, and then, through the
colder season, allows it to be chilled. At some depth, varying with
the latitude, the heat is uniform the year round: this depth in
temperate latitudes at the present time is 25 to 30 feet; under the
equator, 3 to 4 feet; in the frigid zone, but little more than under
the equator. (3.) The amount of heat derived from the sun, and
determining climate, varies with the extent and distribution of the
land (p. 45), and with its elevation,—a wide extent of high or
polar lands being an occasion of cold, and of low or tropical lands
an occasion of warm, climates.
2. Chemical and mechanical action.—All chemical changes in which
there is condensation, as in liquids becoming solids, or gases liquids,
or either increasing their density, evolve heat. This is often an
effect of the natural decomposition of minerals or of vegetable or
animal matter.
All mechanical action, as the beating of waves on a coast, the
falling of water in cascades or rain, the shaking of earthquakes,
sliding of rocks, motion of the atmosphere in winds, produces
heat whenever the action meets with resistance, on the principle
that motion corresponds to an amount of heat, and that heat
appears when the motion ceases. This source of heat lias pro¬
bably produced its effects, although it may be difficult to point
them out.
3. Internal heat.—According to the results of geological research,
internal heat exhibits its effects over the whole surface, in volcanoes,
—earthquakes,—the metamorphism and consolidation of rocks,—
the elevation and subsidence of the earth's crust, raising and de¬
pressing the continents or portions of them as well as islands,
and making mountain-chains.
The proofs of the existence of a source of heat within the earth
are the following :—
1. The spheroidal form of the earth is proof of original fluidity,
and therefore of a subsequent cooling over the exterior from a
state of igneous fluidity.
2. The lowest rocks reached by geological exploration are crys¬
talline rocks,—rocks which, if not once in igneous fusion, have at
least been crystallized through the aid of heat, and heat that must
have reached them from below.
3. Borings for Artesian wells and shafts in mines have afforded a
means of taking the temperature of the earth at different depths;
HEAT.
683
and it has been uniformly found that after passing the limit of
surface-action (p. 682) the heat quite regularly increases. The
rate is 1° F. for 50 or 60 feet of descent. At the Artesian well of
Grenelle, a temperature of 85° F. was obtained at 2000 feet, equi¬
valent to 1° F. for every 60 feet of descent. In Westphalia, at
Neusalzwerk, in a well 2200 feet deep, the temperature at the
bottom was 91° F., or 1° F. for 50 feet of descent. At Pregny, near
Geneva, a depth of 680 feet gave 63° F.
It has been proposed to make a tropical climate in the Garden
of Plants by taking the heat from the earth's interior. Arago and
Waiferdin have estimated that at a depth of 3000 feet the water
would have a temperature of 200° F., " sufficient not only to cheer
the tropical birds and monkeys of the Zoological Gardens and the
hot-houses and green-houses of the establishment, but to give
warm baths to the inhabitants of Paris."
At Yakutsk, Siberia, Magnus found a gain of 15° F. in descending
407 feet, equal to 1° F. for 27 feet.
The rate 1° F. for 50 feet of descent in the latitude of New York
would give heat enough to boil water at a depth of 8100 feet; and
3000° F., the fusing-point of iron, at a depth of about 28 miles.
As the ratio would not be an arithmetical one, since the fusing-
point of any substance is increased by pressure, the depth of fusion
would exceed this amount. But the facts still prove that the earth
has a source of heat within.
4. The warm climate over the whole globe in the early ages, and
the serial diminution of heat with the progress of time until now,
when there is a frigid Arctic, corresponds with the idea of a cooling
globe. This cause appears to have acted conjointly with that con¬
nected with the geographical distribution and height of the land,
referred to on the preceding page.
At present, very little of the interior heat reaches the surface. According to
Poisson, the amount is only one-seventeenth of a degree Fahrenheit; and to reduce
this amount one-half, or to one-thirty-fourth, would now require 100,000,000,000
years. Mr. Hopkins, of England, has stated that, supposing this the only
mode of cooling, it must have required as long a time as this to have dimi¬
nished the temperature the last two or three degrees of its decrease.
5. The wide distribution of volcanoes over the globe is evidence
of internal heat. Volcanoes, extinct or active, border the Pacific
from Fuegia to the Arctic ; through the Aleutian Archipelago to
Asia; down the Asiatic coast, through Kamtchatka, Japan, and the
Philippines, to New Guinea, New Hebrides, and New Zealand ; and
they constitute half of the islands of this ocean, two of which, in
Hawaii, are nearly 14,000 feet high. This volcanic region is equal
684
DYNAMICAL GEOLOGY.
to a whole hemisphere, and therefore sufficient evidence as to the
nature of the whole globe. Volcanoes occur also through Java
and Sumatra; in central Asia in the Thian-clian Mountains ; about
the Mediterranean and Red Seas; in western Asia, and southern,
central, and southwestern Europe; in Iceland, and the West Indies.
The ejection of melted rock through fissures has taken place
over all the continents; in Nova Scotia, Canada, New England,
New Jersey and the States south, the region of Lake Superior, the
Rocky Mountains, and western America; in Ireland, Scotland,
and various parts of Europe ; and so over much of the globe.
These evidences combine to prove that the interior of the earth
is a source of heat.
It is, however, still an open question whether the internal heat
is that of fusion ; or, if there is fusion, whether the whole interior
is fused, or whether there are only interior seas of liquid rock ; or,
if the interior is fused, what is the thickness of the crust. From
a survey of the facts, the most probable conclusion is that the
crust is not over 100 miles thick. Within the crust there may be
isolated seas of melted rock, feeding volcanoes.
Professor Perrey, of Dijon, has inferred from his extended re¬
searches that there is a periodicity in earthquakes dependent on
tides in the internal igneous material of the globe. (See beyond,
on Earthquakes.)
Recent mathematical calculations have made the thickness of the crust to be
at least 800 miles. But the results of figures should not be allowed to suspend
or throw discredit on observations until it is absolutely certain that all the
data required for them are known and thoroughly understood in their various
bearings.
2. EFFECTS OF HEAT.
The effects of heat considered in this place are the following:—
1. Volcanoes and related phenomena ; 2. Non-volcanic igneous
ejections ; 3. Metamorphism and production of mineral veins.
Heat is also one at least of the causes of the elevation of mountains, and
of earthquakes. These topics are considered in the following chapter. It is
an important agent also in most chemical changes ; and hence its effects belong
in part to Chemical Geology.
1. VOLCANOES.
The facts relating to volcanoes are here presented under the fol¬
lowing heads:—(1) General nature of volcanoes, and their geogra¬
phical distribution ; (2) Kinds of volcanic cones; (3) Volcanic action ;
HEAT—VOLCANOES.
685
(4) Origin of the forms of volcanic cones ; (5) Subordinate volcanic
phenomena; (6) Source of volcanoes.
1. General nature of volcanoes, and their geographical
distribution.
1. Volcanoes.—Volcanoes are mountains or hills, of a more or
less conical shape, in a state of igneous action, and consequently
emitting vapors, and occasionally melted rock or lava, with showers
of fragments or cinders, from a central opening called the crater.
They are conduits of fire, opening outward from within or beneath
the earth's crust. An extinct volcano is a volcanic mountain that
has ceased to be active,—the body with the fire out.
The lavas flow out either over the edge or lip of the crater, or,
more commonly, through fissures in the sides or about the base of
the mountain. The cinders are thrown upward from the vent or
crater to a great height, as a jet of sparks or fiery masses, and fall
around in cooled particles or fragments, which are only granulated
lava: they may build up a conical elevation around the vent, or be
carried to a distance by the winds.
When rain or moisture from any source descends with the cin¬
ders, the mass forms tufa,—a stratified, somewhat earthy, granular,
and rather soft rock, of gray, yellowish-brown, and brownish colors.
2. Geographical distribution.—Volcanoes occur (1) over the
border regions of the continents,—that is, the regions between the
oceans and the summit of the border range of mountains, as be¬
tween the Pacific and the summit of the Rocky Mountains; (2) in
the continental islands, or those near sea-coasts; (3) in oceanic
islands, nearly all of which, excepting a few of very large size and
the coral islands, are throughout volcanic,—and the coral islands
have probably a volcanic basis. (4.) Volcanoes are mostly confined
to the borders of the larger ocean, the Pacific and the vicinity of
the seas separating the northern from the southern continents,
namely, the West Indies between North and South America,—the
Mediterranean between Europe and Africa,—the Red Sea between
Asia and Africa,—the East Indies between Asia and Australia.
There are but few about the Atlantic, excepting those of the islands;
and over the interior of continents, remote from the regions men¬
tioned, they are almost unknown.
(5.) Volcanoes are very commonly in linear series or groups.
1. Borders of the Pacific.—The Pacific is almost completely belted with vol¬
canic mountains. They occur in Fuegia, the southern extremity of the Andes;
in Patagonia; 32 in Chili,—that of Aconcagua 23,000 feet high ; 7 or 8 in Bolivia
686
DYNAMICAL GEOLOGY.
and southern Peru,—Arequipa 18,000 feet; 19 or 20 about Quito, nearly all over
14,000 feet, and among them Cotopaxi, 18,876 feet in altitude; in Central
America there are 39 : in Mexico, 7 of large size, with others smaller; in Cali¬
fornia, Oregon, and northwest America, 12, making a lofty series of snowy sum-
Fig. 966.
Volcano of Cotopaxi.
mits, 12,000 to 18,000 feet high,—St. Helen's, in Oregon, 16,000 feet; Mt. Hood,
14,000; Mt. Shasta, 14,000. In the Aleutian Islands, which form a curve like
a festoon across the Northern Pacific, there are 21 islands with volcanoes; in
Kamtchatka, 15 to 20 ; in the Kuriles, 13; in the Japan group, 24, some 10,000
feet high; in the Philippines, 15 to 20; several along the north coast of New
Guinea; a number in New Zealand ; in the Antarctic, on the parallel of 76° 5', and
near the meridian of 168° E., Mts. Erebus and Terror, 12,400 and 10,900 feet high,
both in full action when seen by Ross in 1841; and more to the east, south of
Cape Horn, Deception Island and Bridgeman's.
2. Over the Pacific.—At the Hawaian Islands, there are remains of ten or more
volcanic mountains, and two on Hawaii are now active,—Mt. Loa, 13,760 feet
high, and Mt. Hualalai, about 10,000 feet; while Mt. Kea, on the same island,
13,950 feet high, has not been very long extinct (fig. 24, p. 31, and fig. 973, p. 695).
There are other volcanic mountains at the Society group, Marquesas, Navigator,
Friendly Islands, Feejees, Santa Cruz group, New Hebrides, Ladrones; among
which Tauna and Ambrym in the New Hebrides, Tafoa and Amargura in the
Friendly group, Tinakoro in the Santa Cruz group, and two or three in the
Ladrones, are in action.
3. Over the seas that divide the northern and southern continents from one an¬
other, and the regions in their vicinity.—(a.) The West Indies, where ten islands
are eminently volcanic, (h.) The Mediterranean and its borders, as in Sicily
HEAT—VOLCANOES.
687
and the islands north; Vesuvius, and other parts of Italy; Spain, central
France, Germany, etc., in Europe; the Grecian Archipelago, which contains
five volcanic islands,—Santorin, Milo, Cimolos, Polenos, and Misyros; in Asia
Minor, where are the Catacecaumene and other volcanic regions; and more to
the eastward, towards the Caspian, Mt. Ararat, 16,950 feet high : Little Ararat,
12,800 feet; Demavend, on the south shore of the Caspian, 20,000 feet, (c.) The
Red Sea, along its southern borders, where there are a number of lofty volcanic
summits, (d.) The East Indies, where there are 200 or more volcanoes, of
which there are nearly 50 in Java alone, according to Dr. Junghuhn, and 28 out
of the 50 now active, nearly as many in Sumatra, 109 in the small islands near
Borneo, a number in the Philippines, etc.
4. hi the Indian Ocean.—A few in Madagascar; also the Isle of Bourbon,
Mauritius, and the Comoro Islands, and, to the south, Kerguelen Land, etc.
5. On the Atlantic borders.—Only in the Bight of Benin on the African coast,
where one in the Cameroons Mountains is said to be 14,000 feet high, and the
neighboring islands from Fernando Po to Annabon.
6. hi the Atlantic Ocean.—St. Helena, the Cape Verdes,Canaries, Madeira,
Azores, and Iceland. All the islands of the deep part of the ocean (that is, not
on the European or American borders) are volcanic.
7. Over the interior of the continents.—In America, north and south, there are
none east of the Rocky Mountains and Andes. In Africa, none are known. In
Asia, there is a small volcanic region in the Thian-chan Mountains, at Pe-schan
and Turfan, besides hot springs near Alak-tu-kul, and some other spots in that
vicinity. In Australia, none are known over the interior, the few observed being
situated near its southern border.
2. Kinds of volcanic cones.
As the volcanic mountain is made from its own ejections, it may
consist either (1) of lava alone; (2) of tufa alone; (3) of cinders alone;
(4) of combinations of lavas with either cinders or tvfas, or both. The last
is the more common kind.
1. Lava-cones.—Lavas, when quite liquid, flow off naturally at a
small angle. The average slope of lava-cones is, therefore, very
gentle,—usually between 3 and 10 degrees.
Fig. 967.
L
K
B
=—
A, B, B, C, profile of Hawaii, as seen from the eastward; L, Mt. Loa; K, Mt. Kea.
The great volcanoes of Hawaii (Sandwich or Hawaian Islands),
Mt. Loa and Mt. Kea, shown in the map (fig. 968), and sections of
688 DYNAMICAL GEOLOGY.
which are given in figure 967, are mainly lava-cones, and the gene¬
ral slope is 6 to 8 degrees. (These two figures are parts of one pro-
Fig. 968.
Map of part of Hawaii.
file view of the island, the two joining at B.) Etna has a similar
Fig. 969.
Crater of Kilauea, in 1840: a, large boiling lake of lava; at o and near e, sulphur-banks; r,
an adjoining small crater; p, neck between Kilauea and the crater r.
low inclination. A horizontal section of Mt. Loa, 1800 feet below
its top, would be nearly twenty miles broad.
In true lava-cones, like Mt. Loa, the crater is generally a pit-crater,
HEAT VOLCANOES.
689
—a great depressed area in the surface of the mountain, like a pit
or quarry-hole in a plain, as in the summit-crater of Mt. Loa and
in Kilauea, the latter 4000 feet above the sea. A larger bird's-eye
view of Kilauea (with an adjoining small crater, r) is shown in fig. 909,
and a vertical transverse section of the same, more enlarged, in fig.
970. The pits have precipitous walls of stratified rocks ; for the
lavas are in layers, and the layers are nearly horizontal.
Fig. 970.
Vertical section of crater of Kilauea, 1840.
At Mt. Loa, the summit-crater is 13,000 feet in its longer diameter, and 780
feet deep. Kilauea is 10,000 l'cet in its greatest length, 71 miles in circuit, nearly
four square miles in area, and GOO to 1000 feet deep,—the latter after one of its great
eruptions. It is as much open to the day as a city of two miles square would be
within an encircling wall of 600 feet (the present depth) ; and the pools of boil¬
ing lavas and vapors (one of which is at a, fig. 969) may be as leisurely sur¬
veyed from the brink as if the objects were gardens and cathedrals.
2. Tufa-cones.—Flowing mud from a boiling basin, or cinders wet
with water and steam, take a larger angle of flow than lavas; and
tufa-cones, therefore, have commonly an angle of between 15 and 30
degrees. The layers usually slope inwards towards the bottom of
the crater (fig. 971), as well as outwards down the sides. The tufa
Fig. 971. Fig. 972.
Section of a tufa-cone. Assumption Island, one of the Ladrones.
has a brownisli-yellow color, owing to the action of the steam or hot
water on the cinders, peroxydizing part of the iron in the minerals
(pyroxene mainly) of the lavas, and making a hydrous peroxyd
(p. G5). The crater has generally a saucer shape. A tufa-cone on
Oahu (called Diamond Hill) has a height of 1000 feet. Such cones
are among the results of lateral eruptions about a great volcano
near the sea.
3. Cinder-cones.—Falling cinders, like sand, may make a declivity
of 40 to 45 degrees. The eruption of cinders, therefore, produces a
45
690
DYNAMICAL GEOLOGY.
crater with a narrow throat, a narrow rim above, steep sides, the
slojie 35 to 45 degrees (fig. 972). If the volcano is in brisk action,
the space within the crater is dark with the rising vapors, and
the explosions attending the ejection of cinders occur usually at
short intervals.
The cone is at first nearly black or brownish black, but, if not soon covered
with vegetation, it often becomes, through atmospheric agencies, of a red color,
from the peroxydation of the protoxyd of iron in the lava: the peroxyd of iron
formed differs from that of the tufa-cone in not containing water, and hence
the difference of color. The growth of vegetation tends to change back the
red color to brownish black, since the carbon deoxydizes the peroxyd, making
protoxyd and carbonic acid.
4. Mixed cone's.—The cones which, like Vesuvius, are formed partly
of lava and partly of cinders or tufa, may have any angle of slope
up to 35 degrees. They may be lava below, and terminate in a
lofty cone of cinders of 40 to 45 degrees. The crater may be nearly
like that of the cinder-cone,—a deep cavity, with the walls thin,
compared with those of the simple lava-cone. There is no fixed
order in the alternations of lavas and cinder or tufa layers: the
lavas are apt to prevail most in the early stages of a volcano.
3. Volcanic action. *
The agents concerned in volcanoes are (1) lava; and (2) over¬
heated steam and atmospheric air, with vapors of sulphur, and some
other gases.
The phenomena are (1) Rising and projectile effects of escaping
.vapors ; (2) Movements of the lavas in the crater ; (3) Eruptions.
The facts presented in illustration of this subject are taken mainly from
the volcanoes of Kilauea and Vesuvius, both of which have been visited by the
author.
1. Agents.
1. Kinds of volcanic rocks or lavas.—The fused rock-mate¬
rial is, in all cases, called lava. When solidified, it is lava still, and
is often so termed, whatever its texture ; but in general the name is
restricted to those volcanic rocks which are more or less cellular.
The cellules are usually ragged, and not smooth and almond-shaped
like those of an amygdaloid. The solid kinds, with rarely a cellule
or with none at all, come under the general designation of volcanic
rocks. A very light cellular lava is a scoria, or volcanic slag, or is said
to be scoriaceous.
The principal kinds of volcanic rocks and lavas have been described on pp.
87-89. to which reference may here be made. The most common are dolerite,
dolcritic lava, Inisaft, basaltic lava, clinkstone, trachyte.
HEAT—VOLCANOES.
691
The rock of Vesuvius is lencitophyr, it containing the white mineral leucite
disseminated through it; that of Mt. Loa is mostly of the first four of the kinds
just mentioned. But about some parts, and even at the summit, of Mt. Loa, there
are clinkstone and porphyry,—compact light-colored feldspathic rocks without
cellules. It is not an uncommon fact that, while the ordinary rocks of the ex¬
terior of a volcanic mountain are the heavy cellular dolerites and basalt, those
of the interior (as best seen when the mountain-mass is intersected by profound
gorges) are of these compact feldspathic kinds having no resemblance to ordi¬
nary lavas.
2. Liquidity of lava.—The liquid lava flows usually with nearly
the mobility of melted iron or glass. The whole of the flowing
mass does not, however, appear to be properly in a liquid or melted
condition ; a portion, in unfused grains, is suspended in a fused por¬
tion. As the heat just below the surface has the intensity of what
is called white heat, any part of the rock-material which is fusible
at this temperature, or, rather, which is not consolidated at this
temperature (for the material has come from the depths below,
where the heat is much greater, it increasing with the depth or
'pressure), will be in a melted state. In the crater of Kilauea, the
liquid lava cools at surface into a scoriaceous glass, and this glass was,
beyond doubt, in fusion, like the glass of a glass-furnace,—though
perhaps less perfectly, as stony unfused grains may be disseminated
through it. Below the surface, six inches more or less, the lava
has the aspect of a cellular rock ; but even glass takes this form if
very slowly cooled, and would do so all the more readily if it con¬
tained a large amount of unmelted grains of any stony material.
At Kilauea the liquidity is so complete that jets, but a quarter of an inch
through, are sometimes tossed up from a tiny vent, and as they fall back on one
another make a column of hardened tears of lava. Again, the winds draw
out the glass of the lava-jets in the boiling pools into fine threads, by carrying
off small fragments, and thus make what is called Pole's hair, the crater being
the residence, in native mythology, of the goddess Pele.
The m.obility is also very largely promoted by the vapors rising
in the lava, especially the overheated steam. This is considered its
sole cause by Scrope.
3. Vapors or gases.—Besides air, steam (vapor of water), and
sulphurous vapors (either sulphurous acid or sulphur), there are
sometimes (1) Carbonic acid pas, derived from limestone, and perhaps
from other sources below : (2) Muriatic acid gas, derived from sea-
water, but probably not exclusively.
But these two gases, along with nitrogen and sulphuretted hydrogen, are
mostly emanations from fumaroles,—vents of hot air. steam, or sulphurous fumes,
in the neighborhood of a volcano,—rather than from the liquid lava. Further
examinations of the gases which escape from the liquid lavas in the crater are
692
DYNAMICAL GEOLOGY.
required. About Vesuvius and many other volcanoes incrustations of com¬
mon salt and other chlorids form during an eruption in places a little distant
from the scenes of intensest action; and these, as well as the muriatic acid,
appear to show that sea-water gains access to the lavas; and, if so, fresh waters
also may. The steam may come partly from the depths of the lava, and partly
from superficial waters.
2. Volcanic Phenomena.
1. Rising and projectile effects of escaping vapors.—The water
ancl other vaporizable substances within the lava are under a press¬
ure of about 125 pounds to a square inch for every 100 feet of
depth. Owing to the heat and their consequent expansion, they
slowly rise in the heavy, viscid liquid; as they rise, they keep ex¬
panding, until, nearing the surface, they begin to take the form of
vapors, and finally break through.
The bubble or vapor in boiling water has projectile force enough,
as it breaks at the surface, to throw up water in jets to a height of
two or three inches. Were the resistance greater, as in a more
dense and viscid liquid, the bubbles would become larger by addi¬
tions before they could escape ; the force would therefore be greater
and the jets higher. In lavas which have the freest liquidity, as
those of Kilauea, the jets are thirty to forty feet high. Conse¬
quently, a surface of liquid lava, as in the lakes of lava in Kilauea,
is covered throughout with jets, like a vat of boiling water, and
there is only a muttering noise from the action. It looks like ordi¬
nary ebullition, only the jets are jets of fiery liquid rock. They
rise vertically, and fall back into the pool, or on its sides, before they
have cooled. A lake 1000 feet in diameter (at a, fig. 909) was there
in brilliant play over its whole surface when visited by the author
in 1840; and, in more active times, a large part of the area of four
square miles has been in this boiling state.
If the lavas be less liquid, the vapors are kept from escaping, by
the resistance, until they have collected in far larger bubbles, and,
when such bubbles burst, the projectile force may be enormous; it
carries the fragments far aloft, to descend in a shower of cinders of
great extent.
Such bubbles, rising and bursting, were seen by Spallanzani in the crater of
Stromboli, a high cinder-cone in the Mediterranean, north of Sicily. In times
of moderate action at Vesuvius, the outbursts of cinders occur every three to
ten minutes; but in a period of eruption they are almost incessant. Accord¬
ing to Sir Win. Hamilton, the cinders rose to a height of 10,000 feet at the erup¬
tion of 1779,—a height indicating a vast projectile force. Occasionally masses
of lava are thrown up which descend like huge cannon-balls, having been
rounded by the rotation before they had cooled, and rendered compact exter-
H KAT VOLCA NOES.
693
nally, while usually cellular within. Such masses are called volcanic bombs.
They may have lenticular as well as spheroidal shapes.
2. Movements of the lavas in the crater.—(a.) Upward move¬
ment.—As the vaporizable substances (water, sulphur, etc.) and at¬
mospheric air expand while rising in the volcanic vent, they displace
correspondingly the lava, and so cause a general expansion of the
mass. This alone produces a rise of the lavas in the conduit.
When the boiling of a viscid fluid in a tube causes its upper surface to
ascend, because the liquid at top becomes inflated or frothy with vapor, it
exemplifies the same principle, although the degree of inflation very far exceed?
that in a dense lava. The fact of a rising in the volcano from this cause is
beyond question.
This rising becomes apparent in overflowings from the pools of
the crater, over its bottom, in streams which cool and become solid
lava. Whether the whole rising is due to this cause is not ascer¬
tained. The risings and overflowings are repeated from time to
time, until the material within the crater has reached a height and
an intensity of action that lead to an eruption.
At Kilauca (the bottom of which, when at its lowest mark, is 3000 feet above
the sea) the conduit of liquid lava descending downward below the crater is
3000 feet long to the sea-level; and it may extend many miles, or perhaps scores
of miles, below this. Nineteen miles would correspond to about 100,000 feet.
A rise of the lavas within the crater of 400 to 500 feet in the manner above ex¬
plained is all that in three cases of eruption at Kilauea preceded the outbreak.
Five hundred feet in 100,000 is an average expansion of only a half of one per
cent. But it is probable that the vapors which produce this result are com¬
paratively superficial ,• they may be from the fresh or salt waters of the sur¬
rounding region.
The increase of activity as the lavas rise in a crater has two
obvious causes: (1) the temperature of the lavas increases with the
pressure ; and, consequently, a rise of 100 feet would have increased
very much the temperature at the bottom of that 100 feet, and so
on for greater depths ; (2) the rise exposes a higher column of
liquid lava above to the action of external waters.
(b.) Circulating movement.—In the lava-conduit the greatest heat is
along the centre, most remote from the cold sides. Hence, as in
any cauldron, the ascent from inflation by rising vapors would be
greatest at the centre; there would therefore be at the surface a
flow from the centre to the sides, and a system of circulation. This
was exhibited on a grand scale at Kilauea in 1840, where the liquid
lava in the great lake (1000 feet across, a, fig. 9G9) seemed like a
river that came to the surface for a moment and then disappeared.
694
DYNAMICAL GEOLOGY.
The area of greatest heat was near the northeast side of the lake,
and the stream seemed to flow to the southwest.
3. Eruptions.—(a.) General facts.—The rising of the lavas within
the crater, and the activity of the vapors from one cause or another,
reach such a height and have so great power that an eruption takes
place,—either over the brim of the crater, or through the fractured
mountain. The lavas flow off to a distance sometimes of sixty
miles or more. Examples are given beyond.
The outflow of lavas is attended in most volcanoes, as in Vesuvius,
with the ejection of cinders, and they continue to be thrown out
long after the flow has ceased. They thus build up a cinder-cone
immediately around the open vent.
Most of the small cones about volcanic mountains—called often parasitic
cones—are formed in this manner about a point in some opened fissure from
which lavas were ejected. Cinder and vapor eruptions are the last effects of the
subsiding fires of a volcano. Mt. Ivea is an example of a mountain-cone finish¬
ing its career as an eruptive volcano by the formation of a number of cinder-
cones at summit: their height is 300 to 500 feet. In other cases, the central
vent continues to eject cinders for a long period, and the mountain becomes high
and steep.
Where the liquid rock flows from an open vent or pool, like those of Kilauea,
the lava has a surface-crust, four to six inches thick, of glassy scoria, which is
light and rather fragile. Boiling covers the lavas in the pools with a scum, as
it does molasses, and the scoria is the hardened scum or froth. Below this sco-
riaceous surface the lava is solid rock, often containing only a few ragged cellules.
When the outflow takes place from fissures through which the lavas come up
without having undergone any boiling, the stream is often solid lava through¬
out, without any scoria; the surface is hard and compact, but looks ropy,
owing to the marks of flowing.
Whenever the stream of lava stops on its course, it rapidly hardens over its
surface; if it is then made to move again from another accession of lavas, the
hardened crust breaks up like ice on a pond, but makes black and rough cakes
and blocks 100 to 10,000 cubic feet in size, which lie piled together over acres
or square miles. Such masses are sometimes called clinkers. A large part of
the island of Hawaii is covered by the bare lava-streams,—some with twisted
ropy markings over the surface, drawn out as the sluggish liquid flowed along;
others, extensive clinker-Jiehls, horrid exhibitions of utter desolation.
The streams of lava over the land often rise into great protuberances, many
yards across, with oven-shaped cavities within, formed by waters beneath that
were evaporated by the heat while the flow was in progress.
In a submarine eruption, or wherever the lavas enter the sea, an upper por¬
tion of the outflow, in contact with the water, is shivered to fragments; if in
deep water, the fragments are deposited, and make a stratum of tufa, sometimes
taking a conical form ; if at the water's edge, they rise in a shower of water
and cinders, and fall around, making a tufa-cone, besides spreading far and
wide over the adjoining region ; or they make a permanent boiling basin, which
HEAT VOLCANOES.
G95
also is the centre of a tufa-cone. This latter kind of tufa-cone has a saucer-
shaped crater and the inward and outward slope of the layers represented in
fig. 971; while the preceding may fail mostly of the inward slope.
(b.) Forces causing eruptions of lava.—The forces causing eruption are
as follow:—
A. Hydrostatic pressure in the lavas against the sides of the
mountain. An increase of 500 feet in the depth of the lavas is
an increase of 625 lbs. of pressure to the square inch. Such a
pressure tends to produce fractures for the escape of the lavas.
B. Pressure of vapors. Vapors rising out of the lavas into any
confined space may bring pressure to bear against the sides of the
mountain, and, if suddenly evolved, the effect may cause fracture.
Water may come in contact with hot lavas and enter the sphe¬
roidal state (the state in which a drop of water is when it dances
about on a red-hot stove), and, when so, it will suddenly and explo¬
sively pass into a state of vapor on cooling. This is one cause of
explosion in steam-boilers; and with the apparatus of a volcanic
mountain the results may rend the mountain.
C. Pressure from the slow contraction from cooling going on in
the earth's crust, producing in some regions a subsidence of the
crust and a pressure upward of the liquid rock in or beneath it.
Contraction may also have the reverse effect; that is, it may make
internal cavities in the crust, which may receive such liquids and
draw off the lavas from open vents. It is uncertain whether the
cause acts in either way.
The action of pressure alone is quiet; of vapors gradually evolved,
quiet; of vapors suddenly evolved, either directly or through the
spheroidal state, violent, with earthquakes.
Three eruptions of Kilauea were consequent upon the rise of the lavas to
a height of 400 or 500 feet in the crater, and were attended with no violence.
Fig. 973.
When ready for eruption, there was active ebullition in most parts of the im¬
mense crater, and occasional detonations were heard, but there was no subter¬
ranean shaking.
The eruption in 1840 was without earthquake; and the first sign of the out-
696
DYNAMICAL GEOLOGY.
break was a fire in the woods. The lava broke out through a rent in the sides
of the mountain, about six miles from Kilauea, and appeared for a short dis¬
tance at the surface (A, B, C, fig. 968); then for seven miles there were a few
little patches of lava, and some steaming fissures. Finally, 27 miles from
Kilauea, 12 from the sea, and 1250 feet above tide-level, an outflow began from
fissures and continued on to the sea at Nanawale; and three tufa-cones (fig.
973) were thrown up over these fissures on the sea-shore. It was a tapping of
the mountain and letting out of the lavas; and cotemporaneously they fell 400
feet within the crater,—to p p', fig. 970, which plain then became the bottom
of the lower pit.
The same quiet has attended the eruptions of the summit-crater of Mount
Loa. The courses of some eruptions are shown on the following map.
In January, 1843, an outflow began through fissures 13,000 feet above the
Fig. 974.
Island of Hawaii.—L, Mt. Loa; K, Mt. Kea; H, Mt. Ilualalai; P, Kilauea or Lua-Pele;
1, Eruption of 1843; 2, of 1852; 3, of 1855; 4, of 1859; a, Waimea; 6, Kawaihae; c, Waina-
nalii; d, Kailua; e, Kealakekua; /, Kauianamauna; g, Kailiki; h, "Waioliinu; i, Honuapo;
j, Kapolio; k, Nanawale; I, Waipio. The courses of the currents 1, 2,3 are from a manu¬
script map by T. Coan, and 4, from one by A. F. Judd.
sea (No. 1, fig. 974), and continued on northward and westward for 25 or 30
miles. It broke out in silence, though one of the grandest eruptions on record,
and progressed without an earthquake.
In February, 1852, a bright light at the summit announced another eruption
HEAT—VOLCANOES.
697
(No. 2, fig. 974); after three days it was continued by means of a second out¬
break, 4000 feet lower, or 10,000 above the sea, which also was a quiet one. At
this second opening, as described by T. Coan, there was a fountain of fiery
lavas, 1000 feet broad, playing to a height at times of 700 feet, with indescri¬
bable grandeur and brilliancy. There were rumbling and muttering from the
plunging flood, and explosions, but no earthquakes. Mr. Coan attributed the
fountain to the hydrostatic pressure of the column of lava above.
In August, 1855, another great eruption began (No. 3, fig. 974), without
noise or shakings, at an elevation of 12,000 feet, and for a year and a half the
flood continued: the whole length of the stream* was sixty miles.
In January, 1859, there was still another eruption (No. 4, fig. 974). It made
its first appearance near the summit, in the same quiet manner as the preceding,
Ivilauea remaining undisturbed. About 1500 feet above the sea, on the north¬
west side of the mountain, there was a larger opening, where the lavas were
thrown up, "like the waters of a geyser," to a great height. The stream
here became wider, subdivided into three or more lines, and continued on
towards the base of Mount Ilualalai; from this point it bent northward, and
then northwestward again, and finally entered the sea on the western coast,
after a course of over fifty miles.
There were thus three great eruptions from the summit, with intervals of only
three years and a half, and four within sixteen years.
In the eruptions of Ivilauea—ono of the largest of volcanic craters—there
is evidence only of the action of hydrostatic pressure and of vapors quietly
evolved, as the causes of the outbreak. The fountain had a head of lavas
3000 to 4000 feet high; and 3000 feet of lavas correspond to 3750 pounds of
pressure to the square inch. 'In the eruptions from the summit-crater of Mount
Loa the fountain-head is 10,000 to 13,000 feet above the sea; and the eruptions
were hardly less exclusively a result of hydrostatic pressure.
In the eruptions of Vesuvius, there are usually earthquakes of more or less
power, lofty ejections of cinders and dark vapors, a breaking of the mountain's
summit on one side or the other, or fissures opened in the sides below. In these
violent ejections there may be proof of a sudden evolution of vapors. But
pressure also acts as at Mount Loa; for (he volcano, during the year or more
preceding, has become charged nearly to its brim, ready for the outbreak.
(c.) Eruptions mostly through fissures.—Most eruptions take place
through fissures in the sides of the mountain, and not by overflows
of the craters. The fissures may come to the surface only at inter¬
vals, so as to appear like an interrupted series of rents, although
continuous deep below ; and they may underlie the erupted lavas
as far as the flow extends, although nothing appears to indicate it,
owing to their being concealed from view by the lavas. But fre¬
quently small cones form over the wider parts of the rent, and
stand along the lava-field, marking the courses of the fissures.
This method of eruption through fissures makes dikes (p. 122)
in the mountain ; and all volcanic mountains, when the interior
is exposed by gorges, contain dikes in great numbers. After the
698
DYNAMICAL GEOLOGY.
mending of the fracture by a filling of solid lava, the mountain is
stronger than before.
(d.) Eruptions periodical.—Three eruptions occurred at Kilauea at
intervals of eight to nine years, this being the length of time
required to fill the crater up to the point of outbreak, or four to
five hundred feet. The action was regular in its period, or a result
of a systematic series of changes, and not paroxysmal. The crater
filled up again in eight years after 1840. But, for some reason, the
fires then began to decline (perhaps after a submarine eruption),
and another eruption has not taken place.
Even in the case of Vesuvius—the other type of volcanoes—the
history may be similarly progressive, although the violent activity
excited usually ends in a kind of paroxysmal eruption. There
are, however, so many causes of irregularity that the periodicity,
if existing, would be distinguishable only after a long period of
observation.
(g.) Difference in eruptions due to liquidity of lavas.—At Mount Loa, the
absence of cinders and the low lava-jets prove remarkable liquidity
in the lavas at all times. At Vesuvius the great abundance of
cinder-eruptions proves equally the viscidity of the lavas. In the
latter case, the escape of vapors would be more likely to be
repressed until violent paroxysmal effects became a consequence of
the accumulation; and this may be one reason of the earthquakes
attending the eruptions of such volcanoes.
4. Origin of the forms of volcanic cones.
The general form of the growing mountain has been stated to
depend on the nature of the material ejected, whether lava, tufa,
or cinders, or combinations of these. But there are modifications
arising from other causes. The principal one is the following:—
The angle of declivity in a growing cone depends on the part of
the cone from which the eruptions take place. Overflows at top,
if descending but part of the way to the base, increase the height
and steepness ; but descending all the way to the base they add
to the magnitude of the cone without varying the general slope.
In fissure-eruptions, fissures at the summit widen the top and
increase the slope, for it is like driving in a wedge; but fissures
and outflow about the base spread the base and diminish the ave¬
rage slope: the southeastern slope of Mount Loa spreads out
for a score of miles at an angle of one to three degrees, owing to
this flattening process. The slope, then, of a cone depends on
the concomitant action of the force causing eruption (this force
HEAT—VOLCANOES.
699
fracturing the cone, and sometimes increasing, sometimes dimi¬
nishing, its slope), and the ejection of lava or other material over
the sides.
The slope of flowing lava, while generally small and producing cones of small
angle, may still be of almost any angle. It forms continuous streams of 30°, and
even vertical cascades of solid lava occur about Mount Loa and other volcanoes.
As Prevost observed, flowing lava, like flowing beeswax, if stream follows stream
rather rapidly, and not too copiously, so that one becomes melted to another,
may make layers of great thickness having a large angle of inclination. Hence,
while the average angle of a lava-cone is small, because lavas when in a very
large outflow spread rapidly and easily, there are many regions of much steeper
angle over its declivities. The author observed a stream descending into the
crater of Kilauea at an. angle of 30°. It was, however, hollow, the interior
having run out after the crust had formed. Mr. Coan mentions the frequent
occurrence of slopes of 15°, 20°, and 40° along the stream formed at the erup¬
tion of Mount Loa in 1855.
The outflow of lavas from a vent is an undermining process, and the region
about the crater sometimes subsides as a consequence of it. There are many
fractures and a large depressed border around Kilauea produced by this means.
The violence attending eruptions at times opens widely the mountain and
makes deep gorges that become filled by lavas. Maui, one of the Sandwich
Islands, has a volcanic mountain 10,000 feet high, a crater like Kilauea, at
summit, 2000 feet deep, and two deep valleys with precipitous sides leading
down to the coast, one northward and the other eastward, where the lavas flowed
off at the last eruption. It seems as if a quarter of the island had been started
from its foundations. Oahu consists of parts of two volcanic mountains. The
one of them which is most entire is only a remnant of the old cone,—about one-
third: a precipice twenty miles long and one to two thousand feet high, the
course of a great fracture, is a grand feature of northern Oahu. As there are
small cones over the very region where the large part of the cone has sunk,
the fracture must have occurred before the volcano was extinct.
Mount Somma is part of an outer wall to Vesuvius; and it i^ supposed,
with good reason, that the fracture of the mountain at an eruption reduced the
mountain to its present size.
The Val del Bove is a famous gorge or valley, with precipitous sides, 1000 to
3000 feet high, in the upper slopes of Mount Etna. Fresh-looking lavas cover
the bottom, and dikes intersect the sides. It has been regarded as the result
of subsidence. It is altogether probable, as suggested by the author in his
Report on Volcanoes, that at its head it was once a crater, like Kilauea or the
summit-crater of Maui. The conditions within and about the great depression
accord with this view.
5. Subordinate volcanic phenomena.
1. Solfataras.—Solfataras are areas where sulphur-vapors escape
and sulphur-incrustations form. They occur away from intense
volcanic action. Incrustations of alum are common in such
700
DYNAMICAL GEOLOGY.
places, arising from the action of sulphuric acid on the alumina
and alkali of the lavas. A decomposition of the lavas is another
consequence, producing gypsum (or sulphate of lime) through the
action of the sulphuric acid on the lime of the feldspar or pyr¬
oxene, and also setting the silica free to make incrustations in the
form of opal or quartz, or siliceous earth. Carbonic acid is some¬
times given out in such places, where there is limestone below to be
decomposed,—an acid (either sulphuric acid or silica in solution)
setting free the carbonic acid by combining with the lime.
2. Hot springs.—Hot springs are common in volcanic regions.
The waters may be pure, or of a mineral character. In Tuscany
they give out boracic acid. In Iceland they are large and move in
intermittent jets, and are called Geysers. The tossing of the water,
which is in some cases to a height of 200 feet, is supposed to be
owing to a sudden production of steam in chambers beneath. The
stream, like any other subterranean stream, may have its head in
the mountains. But it comes in contact with the hot rocks, and
the heat and geyser-movement is the consequence. It has been
suggested that the waters are temporarily in the spheroidal state
from contact with the lavas below ; and as they increase by addi¬
tions, after an interval, they suddenly fall below the temperature
requisite for this state, and then the explosion or jet takes place.
The waters decompose the lavas, and take up the silica, owing to
the heat, and the presence of a little alkali derived from the feld¬
spar of the lavas. This silica is deposited around the sides of the
vents, forming a neat bowl-like crater with low sides, and covering
a large region in the vicinity with siliceous depositions, besides
petrifying wood. There is a large geyser-region in New Zealand,
and another in California on the border of the desert. At the latter
boracic acid is given out, as at the Tuscan lagoons.
When the ejection is in a muddy area, as in California, it forms
mud-cones.
6. Source of volcanoes.
The internal fluidity of the globe, or of great regions beneath the
outer crust, being proved, volcanoes are naturally regarded as out¬
lets to the surface of the interior fluid. They mark the points
where the vaporizable materials of the interior, which naturally
work upward, rise through the hardened crust with the lavas they
inflate. Prevost uses the homely comparison of a molasses-cask in
which the fermenting molasses is working out at the bung-hole,—
noting only this difference: that the vapor which does the work
has another source than fermentation. The occurrence of volca-
HEAT VOLCANOES.
701
noes along great lines of mountains, and in linear series, as if over
profound fractures, are facts sustaining this view of tlieir source.
The necessities of any single volcano, like Etna, or a single cluster
of them, like those of Hawaii, might be met by a separate lake
of fire beneath. But when an ocean like the Pacific is girted by
volcanoes, and also blotched all over with the results of volcanic
fires, such a hemisphere of volcanic action needs a vast sea of fire
beneath, if not a hemisphere of igneous action. A volcano is ever
discharging heat into the air by its lavas and gases, and must have
some deep source below.
Supposing the interior of the globe to be fluid, and this to bo
the primary source of volcanic action, it does not follow that a
connection with the interior is retained by every active volcano.
After beginning 011 a fracture reaching through the crust, it may
have become cut off by cooling, so as afterwards to extend only to
a reservoir of liquid rock; when several volcanoes have been
opened on a single profound fracture, they may afterwards have
become wholly disconnected from one another as well as from the,
earth's interior. Known facts about volcanoes do not settle this
question, though favoring the idea of disconnection. Ivilauea, on
the flanks of Mount Loa, is one of the largest volcanic craters on
the globe; and yet eruptions occur at the summit of the same
mountain, 10,003 feet above the level of Ivilauea, and so extensive
that the lavas flow off for 25 to 50 miles without any sign of sym¬
pathy in the lower crater. If the two are connected, the siphon
has the liquid 10,000 feet higher in one leg than in the other.
This connection is possible only on two suppositions:—(1) that it
is at such a depth that 10,000 feet is but a small fraction of the
whole length, and the additional pressure is more than counter¬
balanced by the friction along the conduits; or (2) that, if the
lavas rise in consequence of an inflating process, the difference of
length may not imply a corresponding difference of pressure.
Even about Ivilauea itself eruptions sometimes take pku e
through the upper walls of the crater to the surface (as at P, fig.
968), when the lavas are boiling freely in the bottom of the crater,
undisturbed by the ejection.
While the linear arrangement of the volcanic mountains of a group is evi¬
dence that they all originated in one grand breaking of the earth's crust, the
sever..1 volcanoes in a lino may not stand over one prolonged fracture, but over
a series having a common direction, in the manner illustrated by the figures
on page 19. This was beyond question the mode of origin of the Ilawaiari
Islands.
The islands of Oahu and Maui (see fig. 24, p. 31) consist each of two great
702
DYNAMICAL GEOLOGY.
volcanic mountains united at base, and Hawaii, of three mountains. In the
case of both Oahu and Maui, the northwestern of the two volcanoes became
extinct long before the southeastern,—as is apparent in the profound valleys of
denudation that intersect its slopes and almost obliterate its original features,
while the lavas and parasitic cones of the latter look fresh and recent. In
Hawaii, also, Mount Kea, the northern volcano, is the extinct one. Again, in
the whole Hawaian group the only active volcanoes are iu the southeastern
island, Hawaii, while the northwestern island, Kauai, shows in its features that
its extinction was among the earliest, if not the very earliest, of the whole
number. It appears, therefore, that each, Oahu and Maui, stands over a fissure
which was largest towards the southeast, since the fires of the southeast extre¬
mity of each were last extinguished; that Hawaii had' a similar origin, but
with probably a second more western fissure as the origin of the volcano of
Hualalai; and that the whole Hawaian group originated in a series of fractures
which increased in extent from the northwest to the southeast; for Maui conti¬
nued in eruption long after Oahu (a more western island in the group), and
Hawaii, the southeasternmost, is the only island now active, and the one that
through its prolonged activity has attained the greatest height above the sea.
These facts illustrate a general principle with regard to the fractures of the
earth's crust, as well as the origin of volcanic groups.
2. IGNEOUS ERUPTIONS NOT VOLCANIC.
Non-volcanic igneous eruptions are those that take place through
fissures in regions remote from volcanoes. The cooled rock occu¬
pying the fissure is called a dike. Some of the characteristics of
non-volcanic rocks and dikes are mentioned on pages 117 and 122.
These eruptions have occurred on various parts of all the con¬
tinents, but especially along their mountainous or hilly border-
regions. Examples in New England and along other portions of the
Atlantic border of North America have been mentioned (p. 430),
and others in the Lake Superior region (p. 195). But over the larger
part of the Mississippi basin they are wanting. They abound in
many parts of Europe, and are very numerous in western Great
Britain, especially in Cornwall, Wales, and portions of Scotland, as
well as in Ireland. Fingal's Cave and the Giants' Causeway are
noted examples. They may be not less abundant in eastern Eng¬
land, beneath the covering of Mesozoic and Cenozoic formations
which there prevail.
The columnar form which the rocks often assume—not un¬
known even in volcanic regions—is well illustrated in the accom¬
panying sketch (fig. 975) of a scene in New South Wales.
The dikes differ in width from a fraction of a foot to several
yards or even rods.
The rocks include nearly all the igneous rocks mentioned on
NON-VOLCANIC IGNEOUS ERUPTIONS.
703
pages 8G-89, except the scoriaceous and glassy kinds. Dolerite,
basalt, diorite, and porphyry are the most common. They are
often cellular, owing to inflations by steam or other vapors; but
the cellules have generally a smooth or even surface within, and
are not ragged like those of lavas,—a fact due to their having been
under pressure when formed. When cellular, the rocks are said to
be amygdaloidal, and are often called amygdaloids,—the cavities being
Fig. 975.
Basaltic columns, coast of Ulawana, New South Wales.
occupied usually by zeolites in nodules which are sometimes almond-
shaped.
The fissures were formed by a fracturing of the earth's crust down
to some region of liquid rock, if not to the earth's liquid interior.
They have thus the same origin as volcanoes,—but with this differ¬
ence : that the fissures were not so large as to remain open vents.
In many cases these fissures have been made through the sub¬
sidence of an area of depression, which was continued until the in¬
creasing tension on the lower side of this inverted and subsiding
arch of rock finally caused fractures opening from below upwards,
that gave exit to the liquid rock. The origin of the dikes in the
Connecticut River valley and of those in the Lake Superior region
has been thus explained on pages 432 and 195.
The great numbers and very wide distribution of such dikes over the globe,
taken in connection with the distribution of volcanoes, and regions of meta-
inorphism, leave little room for doubt that the interior of the earth is in a
liquid state, notwithstanding the results of some mathematical calculations.
704
DYNAMICAL GEOLOGY.
3. METAMORPIIISM.
1. General characteristics.
The process of metamorphism is simply a process of change or
alteration, such as has occurred among many of the strata of the
globe after their original deposition. The term is applied especially
when the changes have affected great series of strata, producing,
as an extreme result, a crystallization of the rocks, and, as a more
moderate effect, simple consolidation, and where it is evident that
some degree of heat above the ordinary atmospheric temperature
has been concerned.
Cases of local alteration of structure and crystallization are common, modify¬
ing the composition of isolated crystals or masses. But such changes come
mostly under the term pseudomorphism (from naevdos, false, and poptpr), form). If,
however, as is not unusual, they occur over considerable areas, or near dikes or
veins, and are not due simply to ordinary mineral solutions infiltrating through
a rock or seam, or to some similar local action, hut to a wider cause analogous to
that crystallizing the metamorphic rocks and requiring some elevation of tem¬
perature, they are then examples of true metamorphism. Still, it is often difficult
to draw the line between the two series.
Examples of metamorphic rocks in part fossiliferous are mentioned on pages
270, 391, 392. The famous Carrara marble is an altered Jurassic limestone
underlaid by talcose and mica schist and gneiss. The crystalline rocks of the
Alps are largely of the same age: according to Charpentier, Lardy, and Studer,
Belemnites occur near St. Gothard in a micaceous schist containing garnet;
and in the Grisons, Murchison observed a nummulitic rock turned into a kind
of gneiss. Crystallized limestones in the Urals still retain in places their
Palaeozoic fossils. In the Vosges, corals are said to occur in a hornblendic
rock changed, without a change of form, to hornblende, garnet, and axinite.
The various kinds of metamorphic rocks have been described on
pages 74-84; and examples of the results on a large scale have been
presented at length in the case of rocks of the Azoic age on pages
138-142, and of those of the Palaeozoic ages on pages 409, 410. The
pages referred to are a proper introduction to the review of the
subject and the additional explanations which are here given.
2. Effects of metamorphism.
The principal effects of metamorphism upon rocks are the follow¬
ing:—(1) Consolidation ; (2) Loss of water or other vaporizable in¬
gredients ; (3) Change of color; (4) Obliteration of fossils; (5) Crys¬
tallization, with or without a change of constitution.
1. Consolidation.—Ordinary atmospheric or subterranean waters,
however prolonged their action, do not necessarily produce solidifi-
METAMORPHISM.
705
cation. The soft sandstones of all ages, from the Potsdam to the
incoherent beds of the Post-tertiary, are evidence on this point.
It is probable that deposits to an immense extent have existed in
past time that failed to be consolidated, and were consequently
washed away in the course of subsequent changes.
But, while there are many fragile Potsdam sandstones, there are
others, as those of eastern New York and Vermont, that have been
hardened through the metamorphic process into quartzites or gra¬
nular quartz rocks ; and deposits of sand and pebbles of various
other ages that are refractory sandstones and grits. That the con¬
solidation took place through the metamorphic process, is often
evident from their position within, or on the outskirts of, regions
of other metamorphic rocks. In the same way, fragile absorbent
argillaceous shales have been hardened into firm non-absorbent
slates.
The common modes of consolidation not here included among metamorphic
processes (although the term in its widest meaning might comprehend them)
are the following:—
(a.) Carbonate of lime, derived from granulated shells or limestone, is often
disseminated through arenaceous beds, and, when so, infiltrating waters may
take into solution and deposit again some of the carbonate, and thus cement
the sands. Blocks from a soft calcareous sandstone often increase in hardness
after being removed from a quarry and put into a structure where they are
exposed, over the surface at least, to alternate drying and moistening through
atmospheric causes.
(6.) Beds of sand often contain disseminated grains of some ore of iron, which
are altered by infiltrating waters, and which afterwards become solid and thus
solidify the mass. The decomposition of iron pyrites, and the peroxydation of
its iron, and of that in carbonate of iron and magnetic-iron ore, are the common
methods. The result is often a rock stained, or wholly colored, red or broiviiish-
yellow,—the former color when the process goes on out of water where the atmo¬
sphere has free access. The ferruginous material may also be derived from
external sources.
2. Loss of water or other vaporizable ingredients.—The water contained
in the original material of a rock is sometimes wholly, and some¬
times but partly, expelled. Serpentine is a metamorphic rock
containing 12 per cent, of water; and talcose slate contains 5 or 6
per cent. In many others more crystalline, water is essentially
absent. The bitumen of bituminous coal has been partly or wholly
driven off by the process, and anthracite and semi-bituminous coal
formed (p. 410).
Carbonic acid is expelled from carbonate of lime, or limestone, as
is well known, in a heated lime-kiln. But in the metamorphism of
limestone it is retained. It has been shown by experiment that
46
706
DYNAMICAL GEOLOGY.
the carbonic acid is not given out if the material is under heavy
pressure. If this be true of carbonic acid, it will be so also of
other ingredients less easily expelled.
3. Change of color.—Compact limestones are usually of grayish,
yellowish, brownish, and blackish colors. From the metamorphic
process they often come out white. The original color in these and
argillaceous beds is often due to carbon from ancient plants or
animal matters; and, when so, this carbon is removed and the rock
blanched,—-just as the limestone in a lime-kiln turns white. When
oxyd of iron in any form is present, the blanching does not take
place unless the oxyd is thrown into some new state of combination
in the crystallizing process. When there is only a partial meta-
morphism, its presence generally causes a change of color to red.
4. Obliteration of fossils.—Rocks that have been subjected to the
metamorphic process have usually lost all their original fossils.
Where the metamorphism is partial, the fossils may in part remain,
only obscured. The Devonian coral limestone of Lake Memphre-
magog contains some nearly perfect corals; but most of them are
much flattened and indefinite in outline, and others are only
patches of white crystalline carbonate of lime in a bluish-gray
limestone rock, which is itself hardly at all crystallized. A step
further in the process, and the limestone would have become a
whitish rock of uniform granular texture, with no traces of the
fossils, except, it might be, in white veinings and blotches.
5. Crystallization.—The variety of crystalline rocks formed by the
metamorphic process, and the wide extent of the regions over
which they have been formed, will be learned from the pages
already referred to in the earlier part of this volume. They occur
in all parts of the world, underlying sedimentary formations, if not
at the surface, and they are of various ages, from the Azoic to the
Tertiary. While the Appalachian crystallization and that of New
England took place before the Mesozoic era, that of the Sierra
Nevada in California, according to Whitney, occurred as late as
either the commencement or end of the Cretaceous period; and
that of portions of the Alps, after the Jurassic or Cretaceous.
The crystallization, in some cases, involves no change of com¬
position. This is the fact with most limestone ; the ordinary com¬
pact rock may be simply changed by the process to a crystalline-
granular condition, and bleached in color.
In other cases the constitution is altered, new mineral species
being formed. Argillaceous shales are changed to mica schists, and
argillaceous sandstones to gneiss or granite. Even in the case of
limestone, the impurities are turned into crystalline minerals of
METAMORPHISM.
707
different kinds, such as garnet, idocrase, pyroxene, scapolite, mica, sphene,
chondrodite, apatite, etc.
The crystallization which is produced by the process is of all
grades, from mere solidification of a bed of shale or sandstone, to
the formation of a perfect granite.
3. Origin of metamorphic changes.
Promoting cause.—The great promoter of metamorphic changes is
subterranean heat, acting in conjunction with moisture, and usually, if
not always, under pressure.
The heat requisite for metamorphism is less than that of fusion;
for the evidence is decisive that although the rocks may be so far
softened as to have some degree of plasticity, this is unusual, and
for the most part a comparatively low temperature is all that is
required. It is probable that the results have generally taken
place between 300° and 1200° F.; but it was heat in slow and pro¬
longed action, operating through a period that is long according
to geological measure. A low temperature acting gradually during
an indefinite age—such as Geology proves to have been required
for many of the great changes in the earth's history—would pro¬
duce results that could not be otherwise brought about, even by
greater heat.
The lower limit of temperature is sometimes plaeed mueh below 300° F.;
and, for consolidation it may be rightly so. But there is definite evidence that
it has exceeded this in the majority of cases. In the great faults of the Appa¬
lachians, 10,000 to 20,000 feet in extent, Lower Silurian limestones are brought
up to view, containing their fossils, and not metamorphic. Taking the increase
of temperature in the earth's crust at 1° F. for 60 feet of descent, 10,000 feet
of depth would give 220° F. as the temperature of the limestone before the
faulting, and 20,000 feet would give 390° F. But 1° F. per 60 feet of descent
is the present rate, and must be far short of that at the close of the Carboniferous
age, when the earth's crust was so easily flexed and metamorphism took place
on so grand a scale; and hence the limestone must have been subjected to a
heat far above 220° F., if at a depth of 10,000 feet. The length of time, more¬
over, during which it was thus heated must have been great, as follows from
the age of the rocks and the period of the faulting.
Moisture is essential, because dry rock is a non-conductor of heat
(as well shown in the case of a common fire-brick), and also because
of its chemical powers when heated. Rocks usually contain some
moisture; and, when moist, heat is conducted readily through them.
The pressure may have been either that of superincumbent
waters or of overlying rocks. A little thickness of the latter would
give all the pressure that is in any case essential.
708
DYNAMICAL GEOLOGY.
The evidence that heat has "been the promoting cause is as fol¬
lows :—
1. The effects are analogous to those which heat is known to produce.—
Water, though a weak chemical agent when cold, if heated, has in¬
creased solvent and decomposing powers and increased efficiency in
promoting chemical changes. When heated under pressure above
the boiling-point of water (212° F.), it has the qualities, or is in the
condition of, superheated steam, and is then an exceedingly power¬
ful agent as a destroyer of cohesion and solvent, and a promoter
of decompositions preparatory to recompositions, as Daubree and
others have shown. The moisture disseminated through rocks and
distributed among them would be for the most part, if not every¬
where, in this superheated condition.
When feldspar, or a related mineral, is acted upon by these
means, the waters take its alkalies and silica and become a siliceous
solution, fitted to promote solidification or to make new crystalliza¬
tions ; and when moisture is diffused through a rock containing
feldspathic ingredients, this siliceous solution is alike diffused, and
a simple cooling may cause it to concrete and solidify the mass.
The Geysers afford an example of siliceous waters formed in this
manner. These siliceous solutions, or, more properly, solutions of a
silicate of potash or soda, are in a state to promote combinations,
and, wherever the conditions are favorable, may aid in the form¬
ation anew of feldspar and other silicates.
Crystallizations of epidote, tourmaline, pyroxene, and other species have
been formed in the sandstones adjoining trap dikes, through the heat which the
trap had when ejected. Near Rocky Hill in New Jersey, also on the Delaware
at Lambertsville, and opposite at New Hope, there occur, under these circum¬
stances, short prisms of black tourmaline half an inch in diameter, along with
epidote. The rock has been distinctly baked by the heat in some cases to a
distance of a quarter of a mile, and consolidated to a much greater distance.
A trap dike intersecting the clayey layers, sandstones and coal beds of the
island of Nobby, New South Wales, has baked the clayey layers to a flint-like
rock to a distance of two hundred yards from the dike, the whole length of the
island: the baking effect must have continued much farther,—though the direct
evidence is cut off by the.river.
Daubr6e, besides decomposing various silicates by means of superheated
steam, has made, in this way, quartz crystals, feldspar, pyroxene, and mica, the
crystallization taking place below the point of fusion.
Through the diffusion of superheated steam at a high tempera¬
ture, the rocks may have derived increased flexibility, so that a mate¬
rial otherwise unyielding, as limestone, was flexed under the slowly-
acting pressure, without breaking. The effect may have been even
greater in some cases, and have produced plasticity, or semi-fusion,
METAMORPHISM.
709
in which state limestone might have been pressed into fissures in
adjoining rocks so as to make a species of injected vein. The fis¬
sures and openings in rocks formed while the metamorphism was
in progress, and the distinctness in most cases of the original planes
of lamination, are evidence that this plastic or semi-fused state was
not common in metamorphic operations. It may have been one of
the conditions requisite for the formation of granite,—a non-schist¬
ose rock; and the transitions from gneiss to granite, which are by
imperceptible gradations, may indicate different degrees of this state.
There may seem to be some difficulty in accounting for metamor¬
phic results on the ground of the diversity of mineral species that
are produced. But, in the first place, the elements constituting these
species are few in number,—silica, alumina, potash, soda, lime, mag¬
nesia and the oxyds of iron being all that are necessary for the
great majority of them ; in the second place, the material of sedi¬
mentary strata is, to a large extent, nothing but pulverized metamor¬
phic rocks, so that the metamorphism is often only a new crystal¬
lization of the minerals already present; and, in the third, the
organic remains, out of which many rocks have been largely made,
even the arenaceous and argillaceous, have contributed a variety of
ingredients, besides carbonate of lime,—the most important of
which are phosphoric acid and fluorine (p. 66).
Some argillaceous beds consist largely of true clays, resulting from the decom¬
position of feldspar or other aluminous minerals. But generally they are made
mainly of pulverized feldspar with quartz, as is proved by the presence of alka¬
lies found by chemical analysis. AVhen the alkalies are absent, as Hunt has
stated, metamorphism cannot produce feldspar, but may fill the slate with anda-
lusite, kyanite, or other non-alkaline species.
The following table presents a general view of the composition of the more
common rock-making materials, showing their close similarity. The names
mica and feldspar each include several species : —
Silica Quartz (p. 55).
" + magnesia and water Talc (p. 61).
" " " Serpentine (p. 61).
" " + lime or protoxyd of iron , Pyroxene (p. 60).
" " " " Hornblende (p. 59).
" " + alumina and protoxyd of iron Chlorite (p. 61).
" -I- alumina Andalusite (p. 58).
" " Kyanite (p. 58).
" " + fluorine Topaz (p. 59).
" " + oxyds of iron Staurotide (p. 58).
'< " " " + potash or magnesia. Mica (p. 56).
" . " + hme and soda Scapolite (p. 58).
" " + lime, magnesia, iron, or manganese Garnet (p. 57).
" " + oxyd of iron Epidote (p. 57).
710
DYNAMICAL GEOLOGY.
Silica + alumina and potash, soda, or lime Feldspar (p. 55).
" " + alkali, magnesia, and boraeic acid Tourmaline (p. 58).
The presence of phosphoric acid from organic remains determines often the
formation in metamorphic limestones, and even sometimes in granites, of crystals
of apatite (phosphate of lime); and the presence of fluorine may promote the
crystallization of chonclrodite, topaz, and some other species.
Again, all heated subterranean waters would become mineral
waters, and would serve to carry the material they held in solution
wherever they might have access. In addition, the ocean is a
mineral source as wide as the world, furnished abundantly with
soda and magnesia, and in smaller proportions with many other
ingredients.
2. The attending circumstances were favorable for the escape of subterra¬
nean heat.—The rocks during a period of metamorpliism are under¬
going extensive displacements and foldings, profound fracturings
and faultings, as illustrated in the examples which have been de¬
scribed. Metamorphic rocks are always displaced and folded
rocks, and never for any considerable distance horizontal. Where
the foldings are most numerous and abrupt, reducing the strata to
a system of parallel dips by the pressing of fold upon fold, there,
as remarked by the Professors Rogers, the metamorphism is most
complete. In the case of mineral coal, the bitumen is more com¬
pletely expelled the greater the disturbance of the strata; and in
the metamorphic region of Rhode Island the coal is changed even
to graphite by the heat (p. 410).
3. Thermal springs in metamorphic regions.—The thermal springs of
Virginia are regarded by the Professors Rogers as owing their heat
to the same cause which produced the consolidation and metamor¬
phism in the Appalachian region ; and they instance as evidence
the fact that the localities where they occur are generally situated
over the axis of some fold in the Appalachian strata.
It appears from the above that the escape of subterranean heat
took place during a prolonged epoch of profound subterranean dis¬
turbance. As the epoch slowly progressed, multiplying folds and
fractures, the heat as gradually welled up from below, penetrating
the moist and yielding-beds,—in some regions, where the uplift¬
ing was least, only solidifying the beds; in those most disturbed,
crystallizing them, and filling them with veins.
Local cases of metamorphism from hot mineral waters and dikes
of igneous rocks have occurred without upturnings. But these
cases, while the same in their chemistry, are no examples of the
great physical conditions under which the metamorphism of the
thick formations has taken place.
FORMATION OF VEINS.
711
Herschel brought forward the argument that since there is an increase of tem¬
perature for every sixty feet of descent in the earth's crust, if strata should ac¬
cumulate over a region in the sea to a depth of 10,000 feet, the heat would rise
accordingly into the stratified mass; and, as the same temperature would exist
at a depth of sixty feet as before, there would be accordingly in the lower part of
the mass the same elevated temperature that existed 10,000 feet below the former
surface,—this being a means of raising heat from below without disturbance, and
a degree of heat that in some circumstances might be sufficient for metamor-
phism. But if metamorphism had actually taken place in this way we should
expect to find sections showing horizontal or slightly-disturbed metamorphic beds,
and a gradual transition through a series of such beds to an absence of meta¬
morphism ; but this has nowhere been observed. The great Appalachian faults
(p. 707) are direct testimony against the theory. It is remarkable that even in
the case of the Azoic rocks, formed in a period in which it is supposed the crust of
the earth was thin, there are no examples of metamorphic horizontal beds (p. 144) ;
they lie folded or tilted beneath horizontal Silurian strata in Canada (p. 134).
4. Metamorphism of metamorphic rocks.
Metamorphic rocks are not proof against further metamorphism.
Among the Azoic rocks of northern New York (in Fowler, De
Kalb, Edwards, Russel, Gouverneur, Canton, and Hermon, St.
Lawrence co.) there are extensive beds of a kind of soapstone
(called Rensselaerite) which has in places the cleavage of pyroxene,
showing an alteration of pyroxenic and perhaps other rocks into
soapstone by some magnesian process; and the serpentine of the
region may be of the same period of metamorphic change. Exam¬
ples of the change of crystals and rocks to soapstone or serpentine
occur in the metamorphic regions of New Jersey and Pennsylvania;
and they are common in other countries. Again, in the Azoic of
northern New York, at Diana and other places in Lewis county,
there are beds of a soft compact rock which is sometimes worked
into inkstands, and resembles the agalmatolite of China; and at
one locality there are crystals of nepheline altered to this agalma¬
tolite. These cases of the metamorphism of metamorphic Azoic
rocks may have taken place during the epoch of metamorphism
after the Palaeozoic era, when the rocks of New England were to so
large an extent crystallized.
See further, on the history of this branch of science and its processes, a
Memoir by Daubree, translated from the French by T. Egleston, and published
in the Smithsonian Annual Report (8vo) for 1861.
4. FORMATION OF VEINS.
1. Veins.—Veins occupy either fissures intersecting strata, or
spaces opened between the layers of folded beds. They may result
712
DYNAMICAL GEOLOGY.
from any movement of the rocks, however slight or from whatever
cause ; they abound in all disturbed and metamorphic beds. They
may have great depth, extending through a series of formations, or
be confined to particular strata. Where a disturbance is in pro¬
gress, the different kinds of rock will necessarily be fractured dif¬
ferently, according to their nature. Those that are unyielding or
fragile may be broken into numberless fragments, and these frag¬
ments widely displaced: so that, when the opened spaces or fissures
are filled, the rock will be reticulated with irregular and seemingly
faulted veins. The forming of veins by the opening of layers, alluded
to above, occurs especially in slate-rocks; auriferous quartz veins
are to a great extent of this character. The general forrfts and
other characteristics of veins are described and illustrated on pages
119-123.
2. Methods of filling veins.—There are three ways of filling veins: (1)
by injection from below; (2) by infiltration from above; (3) by
infiltration from the enclosing rocks either side of the vein or
bounding it along some portion of its course. Under the second
and third methods, heat is not absolutely necessary, though generally
required.
First method.—The first method—that by which trap dikes were
formed—is not the common one. There are cases, like that of the
Lake Superior region (p. 195), where metals or metallic ores are
directly associated with injected dikes. But it is always a question,
in such a case, whether the metallic ingredient was derived from
the same deep igneous source with the melted rock of the dike, or
whether it was received from the rocks of the deeper walls of the
fissure during the progress of its injection. The vapors or mineral
solutions produced at such a time often penetrate the rock ad¬
joining the veins, sometimes to considerable distances, either dif¬
fusing ores through them, or filling cracks or long fissures.
Second method.—The second method is exemplified only in super¬
ficial veins, seams, or cavities. Carbonate of lime is often thus de¬
posited in seams or open cavities.
Third method.—The third method is that by which the great ma¬
jority of the veins in metamorphic rocks, whether simply stony
or metalliferous, were produced. The nature of the minerals con¬
stituting veins, their associations, and the banded structure often
characterizing them, are opposed to their formation by injection.
An example of the banded structure is represented in fig. 976, in
which 1, 3, and 6 are sections of layers of quartz ; 2, 4, of gneissoid
granite; and 5, of gneiss ; and other examples are described on
page 123. Such an arrangement could have resulted only from a
FORMATION OF VEINS.
713
lateral filling of the vein by slow and successive supplies of ma¬
terial.
The fissures occupied by veins are simply cavities penetrating the
rocks more or less deeply, sometimes down to re¬
gions of great heat, but not quite to the igneous
interior. During the metamorphic changes, such
cavities, as soon as formed, would begin to receive
mineral solutions or vapors from the rocks adjoin¬
ing. The rocks could contain sufficient moisture
to carry on this system of infiltration, if there
were no other source, and the tendency of cur¬
rents in the moisture, and any vapors present,
would be towards the open spaces. The mineral
matters thus carried to the fissure would there
become concreted, and commence the formation
of the vein. ., ,
sold granite,Valparaiso.
These materials from the adjoining rock may
be taken directly from it by simple solution, or be derived by a
decomposition of some of its constituents. And, when transferred
to a vein, they may be concreted unchanged, or enter into new
compositions through the mutual action of the several ingredients
there collected.
The veins in semi-crystalline slates are mostly of quartz, because
silica is readily taken up by heated waters from siliceous minerals,
and is everywhere abundant. Many are of carbonate of lime, and
for a similar reason. The solutions of carbonate of lime may enter
from above ; but the supply has usually been derived from the ma¬
terials of the adjoining rock through the process of infiltration.
The veins in granitic rocks must have been often formed at the
high temperature required for the metamorpliism of granite, and
the material constituting them is therefore often the same essen¬
tially as that of the granite, only in a coarser state of crystalliza¬
tion.
In the infiltrating pi'ocess, materials that are scattered very widely
and only in minute quantities through the adjoining rocks are
gathered gradually into these open cavities. The crystallizing of the
material held in solution robs the moisture of its mineral portion,
and will lead to a constant re-supply of it from the rock around
as long as the material lasts or the conditions favoring its being
taken up are continued. Thus veins become filled with crystals
of various minerals and ores that are not visible outside of them.
The materials through every portion of a vein are not necessarily
derived from the rock adjoining that portion. The granitic or
Fig. 976.
65 43212 4 56
Banded vein in gneis-
714
DYNAMICAL GEOLOGY
other material derived from its deeper part may rise and occupy
the vein where it intersects slate-rocks.
With this mode of filling, when the process is very slow, the outer
layers, or those lying against the enclosing walls, will be first formed,
and then another layer inside of this, and so on, until the whole,
to the centre, is occupied. By such means the banded structure is
produced. Owing to the varying circumstances during the slow
filling of a vein,—the work sometimes evidently of a long period,—
the infiltrating material varies in kind ; and hence comes the varia¬
tion in the minerals constituting the successive layers, as "described
on page 123. Some of the layers, especially the metallic, may be
formed from vapors or solutions rising from a deeper source than
the range of level along which they occur.
Thus, quartz may be succeeded by fluor spar, and this by an ore
of one or more metals; the last by quartz again, or by calcite; and
so on in various alternations.
If the process of filling were rapid, the vein would fail of this
division into layers. The adjoining rock is often cotemporaneously
altered.
Certain veins in crystalline rocks which blend on either side with the rock ad¬
joining arc sometimes called segregated veins. They are supposed to have been
formed by a segregating process, or a crystallization out of the rock in which
they occur, the direction of the plane of the vein being determined, not by the
previous existence of a fissure, but by magnetic currents through the rock, or
other less intelligible cause. No facts authorize us to infer that magnetic cur¬
rents have the power here attributed to them. Such a blending of a vein with
the walls is a natural result when its formation in a fissure takes place at a high
temperature during the metamorphism or crystallization of the containing rock.
3. Alterations of veins.—Veins do not always retain their original
constitution; and those that are metalliferous are especially liable
to alteration. There are often lines of small cavities through the
middle of a vein or along its sides, or in both ; and, when the rocks
in which they occur are raised above the level of the ocean, the at¬
mospheric waters find access as they become subterranean, and
constantly trickle through them. These waters decompose some
species readily (iron pyrites, etc.), and take the new ingredients
(sulphate of iron, etc.) into solution. Feldspathic minerals maybe
decomposed, and the waters thereby become siliceous and alkaline ;
or, in one way or another, they may become carbonated. Thus
armed, the waters go on making various changes in the ores and
minerals of the vein, altering copper pyrites (sulphuret of copper
and iron) to copper-glance or erubescitc (sulphurets of copper), or
to malachite (carbonate of copper), or changing in a similar manner
ores of silver, or lead, etc. In some parts, the arrangements may
FORMATION OF VEINS.
715
be such as to produce a galvanic effect, further promoting decom¬
positions and recompositions. When the solutions differ, after
intervals of time there will be a succession in the changes, and
layers of different species may be formed.
Thus, a layer of quartz may be succeeded by one of fluor spar, or of zinc
blende, or of caleite, or of quartz again, etc. In the course of the changes, a
layer of cubes of fluor spar, underlying one of quartz, may be entirely dissolved
qway, and the cubical cavities filled up by another species, as zinc blende, etc.
The rock of the walls (especially of the lower wall, where the vein is inclined),
when not united firmly to the vein, often undergoes deep alteration, and may
become penetrated by ores from the vein itself, carried in by infiltrating solu¬
tions. These alterations are most extensive in the upper part of veins, where it
often happens that the metals are removed by infiltrating waters, excepting for
the most part the iron, which is left in the state of red oxyd, giving its color to
the earthy mass at the top of the vein (called then the iron hat). Hence the
occurrence of a line of red earth in the soil may be an indication of a vein of
ore beneath.
Gold-bearing quartz veins generally lose the pyrites and perhaps other ores
which they contain, and thus become cavernous to a considerable depth. To
this distance they are mined with comparative ease; but beyond they are ex¬
tremely hard and difficult to work.
4. Veins of different ages.—In the progress of the uplifting and
folding of a region undergoing metamorpliism, fissures formed at
one time and filled would be liable to be broken by cross-fissures
at some subsequent time in the epoch (perhaps a following day,
week, or year), and these, again, by others. Thus, a succession of
veins faulting one another might be formed during one epoch of
disturbance, and they might differ in constitution as the bands in
a banded vein differ.
Again, veins may be intersected and faulted by fissures formed
during subsequent epochs of disturbance.
It is evident, therefore, that a vein which faults another does not
necessarily belong to a later independent epoch. When actually
later in epoch, it will usually appear in the distribution of the new
veins over a wide region of country, their general parallelism of
direction, and their wholly distinct mineral composition.
5. Filling of amygdaloidal cavities.—The cavities of a lava or igneous rock
(such as arc formed by expanding vapors while the rock is liquid) differ from
veins in size, but not essentially in the method by which they are filled with
minerals. In amygdaloids, these minerals are usually chlorite, quartz, prehnite,
datholitc, analcime, or some of the zeolites, or caleite; and they often occur in
successive layers, analogous to the layers of a banded vein. They are intro¬
duced by infiltrating waters which derive the ingredients mainly from the en¬
closing rock through the decomposition of some of its minerals. Quartz (glassy
quartz, chalcedony, agate, cornelian, etc.) and caleite are the most common of
716
DYNAMICAL GEOLOGY.
these minerals, just as they are in veins. Most of the species in amygdaloidal
cavities are hydrous,—showing that they were formed at a much lower tempera¬
ture than the materials of a granitic vein; and some of them may perhaps be
formed even at the ordinary temperature. When several species occur in suc¬
cessive layers together, the uppermost, or latest formed, usually contain the
most water in their constitution,—silica and calcite excepted, which are not
hydrous species, and may occur at the top or bottom, or any part, of the series.
At Plombieres in France, the cement and brick of walls of Roman origin have
become penetrated in places with zeolites through the action of the water of a
warm (140° to 160° F.) mineral spring (Daubr6e).
VI. MOVEMENTS IN THE EARTH'S CRUST, AND
THEIR CONSEQUENCES.
The topic under consideration in this chapter is the origin of the
movements in the earth's crust or mass, and the methods by which
their results have been brought about. These movements and their
consequences include (1) Changes of position and level; (2) Frac¬
tures, faults, and structural peculiarities produced in rocks; (3)
Earthquakes ; (4) Evolution of the earth's great outlines and reliefs,
and of the successive phases in geological history.
1. CHANGES OF POSITION AND LEVEL.
Changes of position may take place either horizontally or verti¬
cally, or in both directions simultaneously.
1. Causes of change.
Some causes of local change have already been mentioned:—
1. The undermining of strata by the
eroding action of subterranean waters (p.
649).
2. The weight of a superincumbent
mass of horizontal deposits on wet beds
of clay or sand, producing a lateral
movement, and also an extrusion if
the case admits of it (p. 649).—The
laminated clay-layers often become
plicated by the pressure, while the
beds between which they lie are
only slightly compacted or are unaltered. Fig. 977 is a reduced
view of a layer thus plicated, from the Post-tertiary of Boonville,
N.Y. Vanuxem, who mentions the facts in his New York Geolo-
Fig. 977.
Plicated clayey layer.
CHANGES OF LEVEL.
717
gical Report and illustrates them with this and other figures, at¬
tributes the plications to lateral pressure while the layer was in a
softer state than those contiguous. Its porous condition may have
caused it to soften with water more easily than those above or below.
3. The gravity of wet clayey or sandy beds when in an inclined ■position
(p. 650).—The laminated clay-layers are often plicated by this means,
as by the preceding; and some plications in metamorphic rocks are
of this origin.
4. The undermining of strata by volcanic ejections (p. 699).
Other causes are either local or general:—
5. The formation, more or less sudden, of vapors within or beneath some
portion of the earth's crust.—Disturbances in volcanic regions are in
part due to this cause. When in the uplifting and fracturing of
the rocks by this means they become so wedged as not to fall back
to their former position on the condensation or escape of the gases,
a permanent elevation is occasioned.
This cause may produce effects over limited areas. It is often re¬
garded as a prominent means of lifting mountains and continents.
But mountain-chains are heavy, and continents very heavy; and such
vapors, if formed, could at the most only shake the rocky crust.
Mountain-chains and continents could not be sustained long on a
bed of vapors. For permanent elevation, there must be some
mode of holding them up after the uplift. Moreover, there is no
reason to believe in the existence of the cavities beneath requisite
for the spread of the vapors.
6. Weight of accumulating formations over extended areas of the earth's
surface, producing a subsidence of the crust.—Whether this is an
actual cause or not in geological dynamics, is questionable. The
great subsidences of the Appalachian region have been attributed
to it. But this same Appalachian region underwent oscillations
upward as well as downward ; and the former require a very differ¬
ent cause. It was finally, after long ages of preparation, the scene
of disturbances and foldings for a length of 1000 miles and a
breadth of some hundreds ; and these effects of continental extent
are not results of simple gravitation. It is probable that all the
oscillations of level, and the ultimate plication of the crust over
the great region, have one common cause; yet it is not impossible
that gravitation may have been one cause of the subsidences.
7. Movements in the interior fluids of the globe.—If the interior of the
earth has been through the geological ages in a state of free liquidity,
there must have been tides in the molten sea which, in times of ex¬
cessive height, might have caused vibrations of the crust; while if
the condition was that of dense viscidity, such a result could not
718
DYNAMICAL GEOLOGY.
have happened. In neither case could any permanent elevations
of the surface, or any plications of the crust, have arisen from
such a cause. The rocks show that these plications have been ex¬
tremely slow in progress (p. 411), and not a result of any paroxys¬
mal action in forces, above, within, or below the crust.
8. Change of temperature producing expansion and contraction.—Change
of temperature may have acted in two ways:—
(a.) By simple expansion and contraction of some limited region
within the earth's crust, as when heated from proximity to some
volcanic or other igneous source of heat. The effect would be (1)
a rising of the surface, with whatever might be upon it, with the
expansion ; (2) a sinking of the same with the subsequent contrac¬
tion on cooling; (3) a lateral action or pressure on an adjoining
region with the expansion (since it would tend to take place late¬
rally as well as vertically), producing horizontal movements or dis¬
placements of small amount; (4) in some cases, on contraction, an
opening of cracks or fissures, either thickly over the whole sur¬
face (as in the case of basalt and trap when divided into polygonal
columns), or more distant and of greater width. The oscillations
of level in the temple of Jupiter Serapis and along the adjoining
coast have been explained by this method.
(b.) By contraction going on within the earth's interior beneath
its solidified crust. The fact that this cause has acted in the earth's
past is beyond question if the globe was once in a fused state, as is
generally supposed by geologists. Since the crust vrhen formed
would have had the size which the globe then had, all subsequent
cooling, as it would tend to diminish the interior, would bring a
slowly-increasing strain upon it, and, unable to accommodate itself
to the changing size by any process of shrinkage, it must do it
either by fractures or plications, or both.
The effect, in a melted spheroid, of cooling more rapidly at the
surface than within, is illustrated in glass in a Prince Bupert's drop.
The pressure of particle against particle over the whole exterior is
so great from the interior contraction that the removal of a portion
of the surface-layer by a slight scratch of a file destroys the equi¬
librium, and causes it to break instantly, and almost explosively,
to fragments. Another familiar example of contraction beneath
an exterior coat is seen in a drying apple. The exterior, in this
case flexible, gradually becomes wrinkled from the diminution of
size within ; and the wrinkling covers the whole surface alike, unless
some part be protected by resin or otherwise,—in which case the
largest wrinkles would be those about the border of the protected
portion.
CHANGES OF POSITION AND LEVEL.
719
The earth's crust has inequalities of thickness and texture dis¬
tributed probably in large areas; and therefore, while conforming
to the principle exemplified, it should present peculiarities in the
arrangement of the effects dependent on the distribution of these
diverse areas.
The cause is one in which the whole sphere has acted as a unit;
and its effects must, therefore, be coextensive with its surface, but
differing in different parts.
The cause, moreover, must have continued in constant action as
long as cooling continued ; for cooling, however slight, implies con¬
traction and gradually augmenting tension, and an ultimate yield¬
ing when the tension is too great to be longer resisted.
The direction in which a force of this kind acts is approximately
horizontal within the crust, the contraction creating a strain or
pressure between every adjoining part of it; and, wherever the crust
should yield under the tension, some parts wrnuld be, as a primary
effect, drawn downward, and others, as a secondary effect, pushed
upward,—the latter rising through the lateral pressure or pushing
action of the subsiding portion ; and fracture would succeed frac¬
ture, and thus one mass rise over another, or else fold would suc¬
ceed fold in parallel ranges, or both fractures and folds would take
place together. The results would vary writh the nature of the
crust in the part raised, its condition at the time as to the presence
of moisture and heat, and the kind of action in the moving power.
The natural position of the axes of the plications is at right
angles to the direction of the pressure. But if the force is not
uniform, and increases in one direction or the other,—a very pro¬
bable condition,—the plications would show it in variations as to
number, height, and position. Curves might thus result either in
the axes of the plications, or in the line of maximum effect over a
plicated region.
2. Examples of effects under the cause last mentioned, with
additional explanations.
1. The effects universal over the globe.—Since the developments with
regard to the structure of the Appalachians, made in the course of
the geological surveys of the States of Pennsylvania and Virginia,
were first published by the Professors Rogers in 1842, it has been
found that nearly all inclined strata over the globe are actually
portions of plicated strata; and the general principles mentioned
on pages 403-407 (which should here be reviewed by the reader),
although deductions from the special case of the Appalachians,
are, in fact, universal principles. There is evidence everywhere that
720
DYNAMICAL GEOLOGY.
the grander uplifts have been produced by lateral movements of
the crust, and generally a pushing up of the formations into folds.
In the region of southern Virginia and northern Alabama there
is a series of great Appalachian faults, and successive portions of
the crust have been pushed up along sloping faults, bringing the
Lower Silurian limestones to a level with beds of the Carboniferous
Fig. 978.
Section of the Palaeozoic formations of the Appalachians in southern Virginia, between
Walker's Mt. and the Peak Hills (near Peak Creek Valley): F, fault ; a, Lower Silurian
limestone; 6, Upper Silurian ; c, Devonian ; d, Subcarboniferous, with coal beds.
age (Subcarboniferous period); and plications are a minor feature
of the region. But more to the north, in middle and northern
Virginia, and in Pennsylvania, there are great folds, or synclinal
and anticlinal axes, with fewer great faults.
Lesley, after explaining the relations of the eastern or Blue Ridge, the
Great Valley next west, the Appalachian or middle chain, and the Alleghany or
western, and mentioning that the eastern escarpment of the last, " overlooking
the Appalachian ranges with their narrow parallel interval-valleys, is the so-
called Backbone Alleghany Mountain," and separates the head-waters of
nearly all the Atlantic and Western rivers, observes that New River, in
southern Virginia, divides the northern region of plications from the southern
of great faults; and this river is remarkable for cutting through the Appalachians,
and taking its rise even as far east as the Blue Ridge. He adds concerning this
southern district, "The Palajozoic zone included between the Great Valley and
the Backbone escarpment is occupied by as many pairs of parallel mountains
as there are great parallel faults; and, as these faults range in straight lines at
nearly equal distances from each other, these mountains run with remarkable
uniformity side by side for a hundred or two hundred miles, and are finally cut
otf either by short cross-faults, or by slight angular changes in the courses of
the great faults." This strip of country is thirty to forty miles wide, and the
intervals between the fractures or faults are from five to six miles wide. All
have a southeast dip; a portion of the Carboniferous formation forms the south¬
eastern brow of each, overlooking to the southeast Lower Silurian limestone,
and resting on Devonian and Silurian, which come into view to the northwest.
According to the Professors Rogers, these faults in southwestern Virginia,
which were early described by them, occur along the axes of plications, instead
of in monoclinal strata. (Trans. Amer. Assoc. Geol. Nat., p. 494.)
2. The facts in accordance with the supposed origin.—The Professors
Rogers have referred to waves in the earth's liquid interior for an
CHANGES OF POSITION AND LEVEL.
721
explanation of the facts mentioned. Elie de Beaumont and some
other geologists have attributed these effects, and especially the
elevation of mountains, to the contraction of a cooling globe,—
the last of the above-mentioned causes; and this appears to be
the only one adequate for the results.
The facts observed correspond precisely with the effects of the
cause mentioned ; and it is hardly necessary for those readers who
have in mind the structure of the Appalachians as it has been ex¬
plained, to enter here into details. On page 410 it is shown that
the force in the case of the Appalachian region acted in a direction
from the Atlantic Ocean,—that is, at right angles to the axial direc¬
tion of the folds. It follows, therefore, that the subsiding area
which determined the formation of the folds and the uplifts was
beneath the Atlantic Ocean. *
3. Flexibility of rocks.—It is a fact recently established that there
is scarcely any material so solid that when in broad tabular masses
it will not become flexed under a heavy pressure very gradually
applied. By " very gradually" should be understood that degree of
extreme slowness which has so often been exemplified in geological
history, and which is the most common of nature's methods of
progress. The rock or other solid, though apparently inflexible,
will undergo, under such conditions, a molecular movement, adapt¬
ing it to its new condition. Even brittle ice, as stated on p. 673,
becomes flexed by its own weight if a slab be supported by only one
end. There is no doubt that if ice covered a lake to a thickness
of a dozen or more feet, and a slowly-accumulating pressure to a
sufficient amount could be brought to bear against one side of it,
the ice might be plicated over its surface as boldly and numerously
as the formations of the Appalachians.
Fractures have usually been produced in the course of the flexing
of the earth's crust; a violent exertion of pressure under such cir¬
cumstances would naturally produce them on a grand scale; but
they are not an inevitable result of the process of plication. If the
rocks were moist,—as has been the case during these upturnings,—
the plication would take place the more readily. If they were
heated also, and if by this means they were penetrated by super¬
heated water or steam, the mobility of the particles would be still
greater, and they might even have, as observed on p. 708, a degree
of plasticity.
In general, the arenaceous and argillaceous beds which have been
folded were not at the time firmly consolidated, but derived their
consolidation from the heat which escaped from below during the
progress of the movement, and which was the cause of metamor^
47
722 DYNAMICAL GEOLOGY.
phism where the plications were most numerous. Limestone is
always in solid layers unless quite impure.
4. Formation of valleys.—The plication of the earth's crust pro¬
duces alternating depressions and elevations, unless the folds are
pressed together into a close mass. The depressions are synclinal
valleys. The minor valleys of this kind are generally obliterated
by subsequent denudation ; and often even the summits of ridges,
under this latter agency, may consist of the rocks of a synclinal
axis. Besides synclinal valleys, there are often also monoclinal valleys
(p. 720). In addition, there are wider depressions lying between
distant ranges of elevations which were produced through a gentle
bending of the earth's crust (made up of plicated strata or not);
and these great valleys or depressions (like the Mississippi and
Connecticut valleys) may be called geoclinal, the inclination on which
they depend being in the mass of the crust, and not in its strata.
5. Elevation of mountains.—The "force engaged in producing the
great systems of plications over the earth is sufficient for the ele¬
vation of mountains of all heights.
Mountain-chains are not made of igneous ejections, except occa¬
sionally in some small portions.
They are not a result of the mere accumulation of a series of
sedimentary beds; for, when the last layer of such a series is
laid down, the whole is still under water, and some force is re¬
quired to raise them above the ocean, so as to entitle them to a
place among the earth's mountains. And generally there are
plications and metamorphism attending upon such elevation, due,
directly or indirectly, to the same powerful agency. While, then,
they consist mostly of sedimentary beds, altered or unaltered, they
have been raised to their places by an adequate force. Mountains
lifted by lateral pressure or tension within the crust would be sup¬
ported as raised; they would not be resting on a sea of unstable
vapors, but would have a solid basis,—that by the movement of
which they were elevated.
6. Epochs of elevation separated by long intervals.—Mountain-chains
are not the work of the earlier periods of the globe alone, when, it
is believed, the earth's fires were most active, but of particular
epochs in the course of all its ages; and the loftiest of the globe
received much the larger part of their altitude after the close of
the Mesozoic era (p. 503). Plications and disturbances of strata,
and metamorphism, have also occurred at intervals in all ages, and
the two sets of phenomena were partly cotemporaneous.
The special epochs of great uplifts and foldings in eastern North
America have been shown to be—(1) the later part (or close of the
CHANGES OP POSITION AND LEVEL.
723
Laurentian period) of the Azoic age; (2) probably, the close of the
Lower Silurian, for part of the Green Mountains ; (3) the close of the
Palaeozoic era, for the greater part of the Appalachian region,
between Labrador and Alabama. It appears, then, that the ten¬
sion within the crust continued accumulating through long inter¬
vals, before it reached that degree which was sufficient to bring on
an epoch of plication, uplift, and metamorphism. No one will
pretend to count the thousands of centuries between the Azoic era,
or the close of the Lower Silurian, and the close of the Palaeozoic
era. In Europe, and probably in western America, the intervals
were less; moreover, great uplifts, plications, and metamorphism
took place in these regions after the Palaeozoic; but in every case
the period during which tension was accumulating, preparatory for
the epoch of disturbance, was a long one; for the epochs of the
elevation of mountains, even in Europe, are but few in number in
the whole course of past time.
7. Oscillations and minor uplifts.—But during this period of accu¬
mulating tension other and minor effects were apparent. Oscilla¬
tions of the crust, causing changes of level, were going on unceas¬
ingly, and they are yet in progress. The alternations of level
through the Palaeozoic in North America require no other explana¬
tion. They were part of the indications of that living and growing
force which was to exhibit its grandest results after the Carboni¬
ferous age had ended.
8. The water-line of the ocean liable to variations from oceanic subsidences.
—As all parts of the earth, oceanic as well as continental, must
have participated in the changes of level, the water-level was ever
fluctuating like the land-level; and hence it is not safe to measure
the latter always by the former, as is too commonly done. Many
of the apparent elevations may have been due to a deepening of
the oceanic basin,—which has nearly three times the area of the
land (p. 10),—and some of its apparent subsidences may have been
caused by an elevation of its bottom. It is probable that at least
1000 feet of the height of the continents—the average height of
the land of the globe—has arisen from the increase in the depth
of the ocean which took place during the successive Palaeozoic,
Mesozoic, and Cenozoic eras.
9. Mountains small elevations compared with the extent of the globe.—It
should be remembered, in this connection, that mountains are
relatively to the size of the earth but little ridgelets on its surface.
A chain 10,000 feet high would stand up only one-tenth of an inch
on a globe 110 feet in circumference, or 35 feet in diameter,—as
large as many a capacious house; and one-hundredth of an inch would
724
DYNAMICAL GEOLOGY.
correspond on such a globe to the mean height of the continents.
If the Rocky Mountains on a globe of this size were given their
actual slope (equal on the east side to two or three feet in 5000
feet of length), they would be hardly recognizable. The highest
peaks of the Appalachians would have a height of only one-sixteenth
of an inch, and the highest of the globe, of only three-tenths of an inch.
A change of level in the crust of 100 feet, which might, in the ear¬
lier geological ages, have lifted a large part of a continent out of
the sea, would be represented by one-thousandth of an inch on the
same globe. The movements for such effects would relatively,
therefore, be exceedingly small. Considering the length of time
which must have elapsed since the crust of the globe was first formed
and through which contraction has been effecting its changes, and
the vastness of the force that would thus be produced in the crust
of a globe 25,000 miles in circumference, it may rather occasion
surprise that the highest summits stand only 30,000 feet above the
ocean's level, and less than 100,000 feet above the lowest depths of
the oceanic basin.
10. Courses of elevations in a, region the same in different periods.—The
elevations and strike of the rocks in northern New York, which
date from the Azoic age,—the first emergence of the Green Moun¬
tains, dating from the close of the Lower Silurian,—the plications,
elevations, and metamorphism of the larger part of New England,
dating from the close of the Palseozoic era,—the formation of the
trap ridges of the Connecticut River valley, dating from the middle
Mesozoic era,—have the same general direction. The Mesozoic
trap ridges and the plications and uplifts of the Appalachians in
Pennsylvania are also nearly parallel; and the same is true of the
corresponding elevations in Virginia. These few examples are
sufficient to illustrate the principle stated.
11. Courses of elevations in a region not the same in different periods.—
Europe contains many examples of this diversity of direction in
the same region: on page 533 a case of this kind in the Alps is
mentioned. It seems natural that the elevating force should vary
somewhat its direction with the progress of time, or, if remaining
the same, that it should encounter a difference of resistance which
should lead to a result unlike those in former periods.
12. Courses of elevations different in the same period.—The Mesozoic
trap ridges and sandstone of Nova Scotia trend nearly northeast,
those of the Connecticut valley north-by-east, those of Pennsylvania
east-northeast, and those of Virginia northeast-by-nortli; and yet
there is every reason to believe that they belong to the same period
of origin. The Appalachian chain varies much in directions
ORIGIN OF FRACTURES AND FAULTS.
725
southwest of New York ; and there is no evidence that this differ¬
ence is attributable to a difference of age.
While the plications of the rocks of New England are in the
main nearly north-by-east in course, as shown by the strike of the
rocks, there is a region in southern Connecticut where the strike is
transverse to this direction, or parallel to Long Island and the
course of the Appalachians in Pennsylvania; from which it may be
inferred that, cotemporaneously with the action of forces from the
eastward producing the prevailing plications of New England, a
force was also acting from the southward, or at right angles to its
southern coast. The complexity of directions in the White Moun¬
tains may not be owing to a difference of age, but to the combined
action of forces from these two directions.
13. The theory here adopted not in the main hypothetical.—In attri¬
buting the plications of the earth's crust and the elevation of most
mountains to a lateral pushing movement or tension within the
crust, there is nothing that is hypothetical. The statement is the
expression simply of a facti The conclusion that this tension is
due to the contraction of a cooling globe has not yet been fully
established. It is here adopted because no other that is at all
adequate has been presented. The cause must have been one
which would have produced an increasing amount of tension
through the passing periods, causing oscillations of the crust and
minor uplifts in the course of those long periods, and then a
great catastrophe, or an epoch of plications, metamorphism, and
grander uplifts, as a result of the great increase; then another
slow increase and another catastrophe ; then others; and a series
of similar but more or less independent catastrophes in distant
parts of the globe, raising, as late as the Tertiary period, many of
the earth's great mountain-chains,—but one which should cause
only minor oscillations and uplifts in more recent times, since the
earth has now a degree of stability unusual in the past ages (p. 586).
And no cause answers to these demands, so far as known, but
the one mentioned,—the contraction of a cooling globe.
2. FRACTURES, FAULTS, AND STRUCTURAL PECULIARITIES.
1. Fractures.
The following are some of the causes of fractures:—
1. Drying through the heat of the sun, as in the formation of
cracks in mud or earth.—Such cracks are usually but a few
inches deep,—though in the soil of some prairies they occasionally
726
DYNAMICAL GEOLOGY.
extend to the depth of a yard or more, and are two or three inches
wide at top.
2. Baking effect from the heat of igneous ejections.—The adjoining
rock, especially if argillaceous, is often cracked into small columns
of five or six sides, or more, while at the same time hardened.
3. Loss of heat.—Contraction from the loss of heat often pro¬
duces a reticulation of vertical cracks, which are usually too narrow
even for the insertion of a knife-blade, unless the rock contain
considerable moisture. To this cause is to be attributed the divi¬
sion of basalt or trap into columnar forms. (The size of the
columns is, however, dependent on concentric crystallization within
the mass, as explained on p. 98.)
4. A removal of the support of rocks by undermining or other causes.
5. Pressure of a column of liquid rock, as in volcanoes.
6. Expansive force of vapors, especially when suddenly evolved, as in
volcanic regions.
The preceding are local causes of fracture. The last-mentioned
is an exception to this, according to those geologists who attribute
to vapors the elevation of mountains.
7. Tension within the earth's crust,—the same agency which has
been explained on a preceding page as the true source of its plica¬
tions and of the uplifting of mountains. Fractures have been
made, through this means, of all extents, from those intersecting
single layers, to profound breaks reaching down to regions of inter¬
nal fires. In the plication of the rocks, fractures are most likely
to be produced along the axes of the folds where the flexure is
greatest,—those of the upward or anticlinal flexure opening up¬
ward, and those of the downward or synclinal flexure opening
downward. If the latter extend through to the surface, they may
give exit to melted rock. In periods of metamorphism, the lateral
pressure causing the plications appears in general to have so closed
up the fractures made, that igneous ejections were rare. It is not
certain that any took place during the metamorphism of the
Appalachian region; though subsequently, after the rocks had
been stiffened by crystallization, the sinking of the geoclinal val¬
leys occupied by the Mesozoic sandstone formation gave origin to
a great profusion of trap ejections (p. 430).
Direction of fractures.—Fractures, in a region elevated by any
method of pressure, tend to form, as shown by Hopkins, in a direc¬
tion at right angles to the line of greatest strain or pressure, and
also, in many cases, in a second direction transverse to this, making
two systems, a primary and a subordinate.
ORIGIN OP FRACTURES AND FAULTS.
727
2. Faults.
The several causes which may produce fractures through layers
or strata may also cause faults, and the profounder the fractures
the more extensive the faults that may result.
In general, there is a dropping down of the rock on one side of
the fracture by gravity; and, where the fault is a sloping one (as
in fig. 978), the mass on the upper side usually slides down the
sloping plane. But, under the action of the pressure which has
plicated the earth's crust and lifted mountains, the reverse move¬
ment has not been uncommon. The figure referred to is an exam¬
ple ; and, by the upthrow, rocks of the Lower Silurian have been
carried up to the level of those of the Subcarboniferous. Similar
faults may occur along the axes of plications as described by the
Professors Rogers.
In faulting, there may be either a vertical or lateral slide, or an
oblique one. The inequality of the faulted parts of the veins repre¬
sented in the figures on page 121 is accounted for on the ground
of a lateral or oblique slide.
The strata sometimes have a different dip on the sides of a fault (figs. 96,
97). This may arise in different ways.
1. The plane of fracture may not have the same slope in its different parts,
so that in either a vertical or lateral slide parts of unequal dip are brought
together.
2. The rocks may open at the fault, and the parts be adjusted together by
wear of the sides during the downthrow or uplift; and any portion of the
fissure remaining open may be filled by the rubbish thus produced.
3. Wedge-shaped plates, larger below, may separate and fall, leaving the
rock either side of the vacated space to be pressed together by the breaking-
force.
4. Fractures converging downward may separate wedge-shaped masses;
and the rock on one side or the other may fall off some degrees, while the wedge
settles into its new position by gravity, and is adjusted to it by friction in the
descent. If the rock to be faulted has a considerable dip transverse to the direc¬
tion of the force, lateral slides would be of very common occurrence.
5. Plications and uplifts may take place, after a profound fracture in the
rocks, on one side of the fracture, and not on the other. The abrupt transition
in many places between the plicated region of the Appalachians and the
slightly-tilted rocks of the country northwest of them can have no other ex¬
planation.
3. Structural peculiarities: slaty cleavage and jointed
structure.
1. Slaty cleavage.—Slaty structure (exemplified in figs. 89 to 91, p.
101) has been shown, by Sharpe, Sorby, Darwin, and others, to be
728
DYNAMICAL GEOLOGY.
a result of the pressure in action during an uplift. The slates are
transverse to the force. The pressure tends to turn all pebbles or
particles so as to place their flatter side in this transverse position,
and any bubbles present become flattened out in the same way.
Again, in all such action, force taking place in oscillations would
tend to cause transverse lamination.
The laminated structure of ice has been explained by Tyndall
on the same principle (p. 675). Tyndall has proved by experiment
that slaty cleavage may be produced by means of pressure in white
wax, clay, and similar substances, when they are left free to expand
in directions transverse to the pressure.
When argillaceous and arenaceous layers alternate, the former
may receive the slaty structure and the latter not; because the
arenaceous layers, if not too firmly solidified, can accommodate
themselves to the new condition by motion among their partially
adhering particles of sand ; if firmly consolidated, only joints will
be produced, though in some varieties they may be so numerous as
to occasion a coarsely laminated structure.
2. Joints.—Joints are due to the same cause as slaty cleavage,
and may occur in slaty as well as other rocks.
Two systems at right angles to one another often result from
one action, but that in the line of movement is much the least
distinct.
Subjection to pressure from different directions, in different
periods, would produce different systems of joints, and, in slates,
sometimes a new direction of cleavage. •
3. EARTHQUAKES.
1. General characteristics.—Earthquakes are vibrations of the
earth's crust. The vibrations, begun at a line of fracture, or by
a sudden movement or shock of whatever kind, are conveyed in
the rocky crust, just as the sound of a scratch at one end of a log
is carried to the other. If the ear be placed near the ice in
winter, it will hear a crack made in it, although miles off. If the
earth's crust suffer an abrupt fracture somewhere in its depths
where tension has long been, increasing and has finally forced a
relief, the vibration may move on through a hemisphere, and will
be almost regardless of the mountains on the surface.
Earthquakes are of two kinds:—
(1.) A simple vibratory movement, without any permanent dis«
placement of the rocks.
(2.) A vibration accompanying an uplift.
EARTHQUAKES.
729
The latter is far the most violent, as the simple impulse of
vibration has an additional onward progression equivalent to the
uplift or displacement.
Besides these wave-movements, there are also, in most cases,
the very rapid wave which gives sound to the ear. The sound¬
wave may be felt before the translation-wave, and may travel
farther. At the shock of St. Vincent, in 1812, sounds like thun¬
der were heard over several thousand square miles in the Caraccas.
the plains of Calaboso, and on the banks of the Rio Apure. At
the Lima earthquake, in 1746, a subterranean noise, like a thun¬
der-clap, was heard at Truxillo, where the earthquake did not
reach.
The rate will vary with the elasticity of the rock, and somewhat,
also, with the elevations over the surface.
2. Regular progression in earthquakes.—Regular progression
may be a usual fact, although not generally observed. Professor
Rogers has shown that an earthquake, on the 4tli of January,
1843, traversed the United States from its northwestern military
posts, beyond the Mississippi, to Georgia and South Carolina, along
an east-southeast course, Natchez lying on the southern border
and Iowa about the northern. The rate of travel ascertained was
thirty-two to thirty-four miles a minute.
3. Phenomena attending earthquakes.—(1) Fractures of the
earth, sometimes of great extent; (2) subsidences or elevations
of extended regions, and draining of lakes ; (3) displacements of
loose rocks, and, where a mass overlies another and is not attached
to it by its precise centre, a partial revolution, resulting from an
onward impulse ; (4) destruction of life in the sea, on the same
principle that a blow on the ice of a pond will stun or kill the fish
in the waters beneath ; (5) production of forced waves in the ocean;
(6) destruction of life on the land. Destructions of cities and of
human life have been too often recounted to need special illustra¬
tion in this place.
The elevations that take place are sometimes spoken of as
effects of an earthquake, although not properly so. Vibration may
be attended by fractures and uplifts; but these effects result from
the cause that produces the shaking.
Some of the elevations and subsidences that have attended
earthquakes are mentioned on page 588.
4. Earthquake oceanic waves have been alluded to on page
655. One or two additional examples of their effects may here be
added. In 1755, accompanying the Lisbon earthquake, the sea
came in in a wave 40 feet high in the Tagus, 60 at Cadiz, 18 on the
730
DYNAMICAL GEOLOGY.
shores of Madeira, 8 to 10 on the coast of Cornwall. One in 1746,
on the coast of Peru, deluged the sea-port Callao, and the city of
Lima seven miles from the coast, sunk 23 vessels, and carried a fri¬
gate several miles inland. Two hundred shocks were experienced
in 24 hours. The ocean twice retreated, to rush in a lofty wave over
the land. The shock to a vessel from an earthquake wave is as if
it had received a heavy blow or had struck a rock.
According to Professor Baclie, the oceanic waves, produced by
the great earthquake at Simoda (Japan) in 1854, crossed the Pacific,
and were registered, as to their number, intervals, and forms, on the
self-registering tide-gauges of the Coast Survey along the coast of
Oregon and California; and from the data thus afforded he was
enabled to calculate the mean depth of the intervening ocean,
stated on page 12.
5. Causes of earthquakes.—(1.) The tension and pressure by which
the great oscillations and plications of the earth's crust have been produced.—
The effects of this tension have not yet wholly ceased. This is
probably the most general cause of earthquakes.
The uplifting of the formations, moreover, must have always left
the interior of the crust in a state of unstable equilibrium; and
any incipient slide in the progress of time along an old fracture,
or between tilted beds, would be attended by an earthquake-shock.
All are familiar with the cracking sounds occurring at inter¬
vals in a board floor of a house, and arising from change of tem¬
perature, especially in a room in winter that is heated during
the day; and with the more common sounds of similar character
from the jointed metallic pipe of a stove or furnace given out after
a fire is first made, or during its decline. In each case, there is a
strain or tension accumulating for a while from contraction or
expansion, which relieves itself, finally, by a movement or slip
at some point, though too slight a one to be perceived; and the
action and effects are quite analogous to those connected with the
lighter kind of earthquakes.
(2.) Any cause of extensive fracture or movement,—as the under¬
mining of strata, the sudden evolution of vapors, etc.
(3.) Tidal waves in the internal igneous material of the globe.—This hy¬
pothesis supposes the material of the interior to be sufficiently
liquid to have waves, and the crust to be thin.
Some investigations by Professor Alexis Perrey, of Dijon, France,
seem to indicate that there is a periodicity in earthquakes synchro¬
nous with that in the tides of the ocean,—the greatest number
occurring at the season of the syzygies in each lunar month. If
this be sustained by further research, the cause must be admitted
EVOLUTION OF THE EARTH'S OUTLINES.
731
to be a true one. Its sole effect, however, may be to determine the
occurrence of earthquakes where another more powerful agency, as
that first mentioned, had prepared the conditions and made all
ready for the movement. If there are internal tides, and they have
this much of power, earthquakes would be most frequent at the
syzygies, and least at the quadratures, as Professor Perrey con¬
cludes to be the fact.
4. EVOLUTION OF THE EARTH'S GREAT OUTLINES AND RE¬
LIEFS, AND OF THE SUCCESSIVE PHASES IN ITS
PROGRESS.
1. Evolution of the Earth's Outlines and Reliefs.
1. General laws as to arrangement.
In the chapter on the General Features of the Earth (pp. 9-39),
it has been shown that there is a system in the arrangement of
its reliefs and outlines. Whatever force, therefore, originated the
great mountain-chains originated not merely independent moun¬
tains, but the system of reliefs of the sphere.
The general principles connected with this system,announced in
the chapter referred to, or brought out in the later pages of the
volume, are the following:—
I. The continents have mountains along their borders, while the
interior is relatively low ; and these border mountain-chains often
consist of two or three ranges elevated at different epochs.
II. The highest mountain-border faces the largest ocean, and
conversely.
III. The continents have their volcanoes mainly on their bor¬
ders, the interior being almost wholly without them, although
they were largely covered with salt water from the Azoic age to the
Tertiary. Also metamorphic rocks later than the Azoic are most
prevalent near the borders.
IV. Nearly all of the volcanoes of a continent are on that border
which faces the largest ocean.
Y. The strata of the continental borders are for the most part
plicated on a grand scale, while those of the interior are relatively
but little disturbed.
VI. The successive changes of level on coasts, even from the
Azoic age to the Tertiary, have been in general parallel to the
border mountain-chains; as those of the eastern United States,
parallel to the Appalachians, and those of the Pacific side, as far
as now appears, parallel to the Rocky Mountains.
732
DYNAMICAL GEOLOGY.
VII. The continents and oceans had their general outline or
form defined in earliest time. This has been proved with regard
to North America from the position and distribution of the first
beds of the Lower Silurian,—those of the Potsdam epoch. The
facts indicate that the continent of North America had its surface
near tide-level, part above and part below it (p. 196); and this will
probably be proved to be the condition in Primordial time of the
other continents also. And, if the outlines of the continents were
marked out, it follows that the outlines of the oceans were no
less so.
VIII. The prevalent courses of coast-lines, mountain-chains, and
groups of islands over the globe are two,—one between the north¬
east and southwest, and the other between the northwest and
southeast (p. 30).
IX. In the courses of the earth's outlines, while there are two
prevalent trends, there are very commonly curves:—in some cases
a gradual curve, as from E.N.E. to N.N.E., as in the great central
chain of the Pacific, or from N.E. to E. and then to N.N.E., as in
the line from New Zealand to Malacca (p. 32); in others, a series
of several curves, meeting one another nearly at right angles, as
in the island-ranges off the Asiatic coast (p. 36).
X. The earth towards or about the equatorial regions is belted
with oceanic waters separating its northern and southern conti¬
nents, passing through the East Indies, Red Sea, Mediterranean,
and West Indies; and this region is remarkable for its volcanoes
(p. 686).
The preceding are some of the comprehensive characteristics of
the globe which exhibit the system that pervades its physiognomy
and illustrate the manner in which this system was educed.
2. Deductions from the positions of the reliefs.
1. The situation of the great mountain-chains, mainly near the
borders of the continents, does not indicate whether the elevating
pressure acted within the continental or oceanic part of the earth's
crust. But the occurrence between the principal range and the
sea-coast of the larger part of the volcanoes (and, therefore, of the
profound and widely-opened fractures) of these borders, of the
most extensive metamorphic areas, and the closest and most nume¬
rous plications of the strata, as so well shown in North An;erica,
are sufficient evidence that the force acted most strongly from the
oceanic direction.
2. The relation between the extent of the oceans and the height
and volcanic action, etc. of their borders proves that the amount
EVOLUTION OF THE EARTH'S OUTLINES. 733
of force in action had some relation to the size and depth of the
oceanic basin. The Pacific exhibits its greatness in the lofty moun¬
tains and volcanoes which begirt it.
3. In such a movement, elevation in one part supposes necessarily
subsidence in another; and, while the continental was the part
of the crust which was elevated, the oceanic was the subsiding
part.
The oscillations, plications, and elevations alluded to began in
the Azoic age: hence the conclusion that the oceanic basins and
continents were early outlined is unavoidable. The sinking of the
ocean's bed and the rising of the continents were concurrent effects
of one cause. The raising of mountains reached its climax in the
Tertiary period: from that time the^ effects have declined.
4. If, then, the continents were from the beginning the nearly
stable areas (as appears also from the absence of volcanoes from
their interior, while they abound in the oceans), the pressure of
the subsiding oceanic portion has acted against the resisting mass
of the continents; and thus the border between them has become
elevated, plicated, metamorphosed, and embossed with volcanoes.
5. The position of the Urals between Europe and Asia is in
accordance with the theory ; for in a continent so broad from east
to west as the Orient, the tension and movements within the conti¬
nental crust would naturally occasion some elevations.
6. "While the Alps may have been elevated by the tension within
the oceanic crust, the Juras appear to have been a reacting effect
of elevation in the region of the Alps; for the plications are most
numerous towards the Alps, instead of towards the ocean.
7. The cause of this tension and pressure within the crust has
been attributed, on a former page, to the secular refrigeration of
the globe. No other cause presents itself that can comprehend in
its action the whole globe and all time.
The universality of this cause is also exhibited in the cotempo-
raneousness of even some of the minor oscillations of the surface
of different continents,—as, for example, the condition of submer¬
gence in Europe and America preceding the Coal period, which
favored the formation of the Subcarboniferous limestone on both ;
the condition of progressing emergence required for the succeed¬
ing Millstone grit; and then that of the general, though slight,
emergence requisite for the Coal period itself (p. 394).
It has been shown (p. 569) that after the Tertiary period the
system of oscillations of the earth changed to a high-latitude sys¬
tem, both in the northern and southern hemispheres. This, again,
exhibits the comprehensiveness of the great cause. It is probable
734
DYNAMICAL GEOLOGY.
that these transverse or latitudinal oscillations, while most promi¬
nent in the higher latitudes, also had their lower-latitude effects;
that they resulted in deepening the transverse seas that divide the
northern and southern continents. For the occurrence of Post-
tertiary animals on Sicily, Malta, and Gozo, in the Mediterranean,
similar to those of Africa, is strong testimony, as some writers have
observed, that these islands were joined to the mainland on the
south even in the last period of geological history, when the Age
of Man was opening. The barrier coral reefs and coral islands of
the East and West Indies indicate as recent depressions in those
inter-continental seas. Even the origin of the British Channel,
as some have thought, may be of the same period, if the identity
of European and British Post-tertiary mammals is not to be ex¬
plained by independent creations in the now disjoined lands.
Moreover, the Pacific Ocean, within the tropics, has registers of
subsidence all over it, in its coral islands.
3. Deductions from the courses of the reliefs and outlines.
The prevalent northeast and northwest courses of trends, the
curves in the lines varying the direction from these courses, and the
dependence of the outlines and feature-lines of the continents and
oceanic lands upon these courses, are the profoundest evidence of
unity of development in the earth. Such lines of uplift are lines
of fracture, or lines of weakest cohesion; and therefore, like the
courses of cleavage in crystals, they show by their prevalence some
traces of a cleavage-structure in the earth,—in other words, a ten¬
dency to break in two transverse directions rather than others.
Such a cleavage-structure would follow from the nature of the
earth's crust. The crust has thickened by cooling until now scores
of miles through, and very much as ice thickens,—by additions to
its lower surface. Ice takes on a columnar structure, perpendi¬
cular to the surface, in the process, so as often to break into columns
on slow melting. The earth's crust contains as its principal ingre¬
dient the cleavable mineral feldspar; and as the crystals of this
mineral usually take a parallel position in a granite, so that the
granite of a quarry has its directions of easiest fracture, so it might
be in the cooling crust. This appears the more probable when it
is considered with what extreme slowness the thickening of the
crust has gone on, and the immeasurable length of time it has
occupied.
There are three elements at the basis of the earth's features.
First, a geographical one,—the positions and extent of the con-
EVOLUTION OP THE EARTH'S OUTLINES.
735
tinents, or comparatively stable areas, in relation to the oceans, or
more subsiding areas; the second, structural,—the system of cleavage-
structure ; the third, dynamical,—the tension in the crust itself accu¬
mulating most through the subsiding of the oceanic basins.
The features of the oceanic basins and the position of the con¬
tinents determine the general bearing of the tension ; and the
cleavage-structure, or courses of weakest cohesion, tends to give
direction to its effects. The North Atlantic follows one of the
cleavage-courses, the Pacific another (page 36); North America is
bounded by the two, and hence its triangular form. See, further,
on these lines, pages 30 to 39.
The courses of the rents or uplifts in such a crust will depend
on the direction of the tension in connection with the cleavage;
just as in a piece of cloth the rents from stretching it will vary
with the direction of the force.
Force exerted at right angles to the lines of structure, and equal
along the line, would produce a straight series of rents or uplifts
(figs. 11, 12, p. 19).
If not equal along a given line, the rents might together make
an oblique or curving series (figs. 14, 15, p. 19). If the tension were
oblique to the structure-courses, the series of rents would be oblique,
and, as above, either straight or curved.
Hence curves are necessarily in the system.
The coincidence between the trend of the Pacific (northwest and
southeast), the mean trend of the Pacific islands (p. 34), and the
axis of the coral-island subsidence (p. 587), shows that the ocean
in its movements has been one great area of oscillation. The cen¬
tral curving range, 6000 miles long, lies on the southern side of the
axis of this great approximately elliptical area. The tension in this
subsiding area itself appears here to be the cause of the long curve.
The double or" triple system of curves around Australia, from
New Hebrides, or perhaps northern New Zealand, to New Guinea
and Timor, are such as might arise from the Pacific tension, acting
against that stable continental area of Australia ; for they are con¬
centric with it; and the branch of the central Pacific chain leading
off westward through the Carolines has been shown, on page 34, to
conform to this Australian system. The rising curve from Java,
through Sumatra, suggests that here the oceanic basin on the other
side of Australia (the Indian Ocean) has brought tension to bear
against the Asiatic continental area; and this is further confirmed
by the fact that the deep-water channel separating the Australian
seas from the Asiatic passes just north of New Guinea and Timor
and south of Java.
736 DYNAMICAL GEOLOGY. '
The East Indian Archipelago lies between the North Pacific and
the Indian Ocean ; and the two, along with the reacting stable con¬
tinental areas, have together modelled out the group. The West
Indian Archipelago has a similar position between the North At¬
lantic and the South Pacific, and hence the resemblances to the
East Indian pointed out on page 37.
The curves along eastern Asia, in the islands and continental
mountain-ranges (page 36), seem to show that the tension across
the Pacific area, which produced the curves, was unequal along
different lines. The courses and positions of the groups of Pacific
islands prove that the bottom has its ranges of southeast and
northwest elevations and depressions, crossing the ocean; and this
would occasion the unequal tension required.
Between the directions of the structure-lines and the directions
of the acting force, as determined by the oceanic and continental
areas, the origin of the prevalent trends and of their frequent
curving courses may therefore be explained.
4. Application to North America.
The geological progress of Nordi America was an evolution of a
continent under the two great systems of forces, the Atlantic and
the Pacific. The Appalachians, with their many folds, are a proof
of the reality of the former; and the Rocky Mountains, with their
parallel ranges,—the great volcanic chain and Sierra Nevada near
the coast, the double crest about the summits, and other ranges
across an area one thousand miles in breadth,—are equally a proof
of the reality and vast power of the latter. The Azoic land from
Lake Superior to the Arctic was the result of an Azoic action of the
Pacific force; and that from Lake Superior to Labrador, of the At¬
lantic force. This, as shown on page 136, was the Azoic nucleus,
from which the growth went onward,mainly through the oscillating
energies to the southeast and southwest. This fixed the position
of Hudson's Bay, for it is between the arms of the Y. This enlarged
the continent to the southeast and southwest, spreading out the
strata under the oscillations occasioned, finally doubling the V by
adding the Appalachians and the Rocky Mountains, and tripling
it later on the west by the Cascade and other ranges.
Effects of the meeting and crossing of the two forces over North
America, that from the southeast and that from the southwest, are
seen in the line of the Illinois uplifts and Florida (pp. 320, 531), of
the latter system, intersecting the Appalachian chain in eastern Ten¬
nessee. The area of the uplifted Lower Silurian about Cincinnati
EVOLUTION OF THE EARTH'S OUTLINES.
737
is intermediate between the two; and it is interesting to observe
that its distance from the small Atlantic is 500 miles, from the great
Pacific 2000 ; a ratio of 1: 4.
The Azoic nucleus of North America, spreading southward, formed
a peninsula in northern New York. Even this bend in the nucleus
continues in the finished continent, for New England has the same
outline. Its east and south coast-lines are but a repetition of the
east and south coast-lines of the old Azoic peninsula. This exact
copying of the nucleus by the growing continent proves, better
than all other evidence, the grand fact that the progress has been
through oscillating forces acting against the stable Azoic nucleus,
and also that the system of evolution has been under profound
law.
2. Origin of the Successive Phases in the Earth's Progress.
1. Epochs.—The epochs in geological history were marked by
transitions in the strata and by more or less complete extermina¬
tions of life. These transitions, as has been already explained (p.
398), were directly connected with oscillations in the water-level
about the continental areas; and this water-level was changed by
elevations and subsidences either in the continental or the oceanic
portion of the crust, or the two united (p. 723). Violent paroxys¬
mal uplifts and downthrows, and also effusions of heat, were among
the events here included, as well as the gentler changes of level
that were barely apparent with the passing of a century. But far
the larger part even of the seemingly abrupt transitions required
only the latter.
The succession of epochs in history and the development of the
earth's features, were, therefore, concomitant results in the same
plan of evolution.
2. Climate.—Three causes have been presented to account for
the cooling of the climate of the globe in past time:—
1. The decreasing density and cloudiness of the atmosphere, through a
diminution of the proportion of carbonic acid and moisture.
2. The increasing extent and height of the land.
3. The secular refrigeration of the globe.
Two other supposed causes are sometimes brought forward:—
4. A change in the earth's poles.—Such an event would only change
the location of the frigid zone or polar climate. When it has been
proved that there was a polar climate anywhere in the Palaeozoic
ages, and what its location was, it will be soon enough to arrange
this among possible causes. Astronomers deny its possibility.
5. A passing of the earth through warm regions in space during its earlier
48
738
DYNAMICAL GEOLOGY.
eras.—This cause is so far within the region of the hypothetical as
hardly to merit consideration until all others admitting of investi¬
gation have been proved insufficient.
The first of these causes is beyond doubt a real one ; yet its
effects must have been too small, especially after the Carboniferous
age, to have produced the whole amount of change which took
place.
The second is also of undoubted value, as explained on page 45.
To appreciate its influence, it is necessary to suppose the existing
globe with its climates changed in its lands. For example, to pro¬
duce the climate of the Coal period, the amount of land should be
reduced one-half in area, far the larger part of this be brought
nearly to the ocean's level, all the highest mountains be lowered
or levelled, and the greatest elevations made not to exceed 6000 or
8000 feet, and then to be of comparatively limited extent.
The Polar lands were in existence, as the coal fields show, but
may have been comparatively small. Facts seem to prove that
such changes might reduce the higher latitudes to the condition
of Fuegia. But Fuegia has alpine plants within one thousand feet
of the sea, and a mean temperature but little above freezing. The
result is still not what the facts require; for there is no reason to
believe that there was any alpine or sub-frigid vegetation at Melville
Island, or that the plants differed essentially from those of Penn¬
sylvania. This warm climate of the poles was hardly less striking
in the middle Mesozoic. For, while Eeptiles are especially charac¬
teristic of the tropics, there were Ichthyosaurs and Tel-eosaurs in
the Arctic. Sir Edward Belcher found an Ichthyosaur on Exmouth
Island, in latitude 77° 16' N. and longitude 96° W., 570 feet above
the present sea-level; and CaptainSherard Osborn found two bones
of a species allied to the Teleosaur on Bathurst Island, in latitude
76° 22' N. and longitude 104° W.
The third cause mentioned has unquestionably acted in the
earth's history, if the globe was once in igneous fusion. But it
may well be questioned whether by the commencement of the
Silurian age the crust had not attained a thickness which would
have rendered the internal fires no longer a source of heat for the
earth's surface. That the heat issuing through the crust was so
great at the poles in the Carboniferous age as to raise the mean
temperature, by radiation into the atmosphere, from 40° F. to 60° F.
(the climate probably required for the vegetation of the era), is not
true; for the same amount of change in the temperate and tro¬
pical zones would have rendered them uninhabitable by most plants
and animals. But some few degrees of heat may have been received
SUCCESSIVE STAGES IN THE EARTH'S PROGRESS. 739
by the waters of the ocean,—especially if the crust beneath the
ocean were originally thinner than the continental portion, as may
be inferred from its being the portion which subsided most during
the earth's contraction. A small change in the ocean would have
produced great effects over the globe, through the oceanic currents.
The cooling of the climate of the earth is probably due to all
three of these causes ; but the exact effect of each in bringing
about the result, it is impossible, in the present state of science, to
estimate.
3. Progress in the earth accords with the universal law of
development.—The general law at the basis of all development is
strikingly exhibited in the earth's physical progress, as has been
well shown by Guyot. The law is simply this:—Unity evolving
multiplicity of parts through successive individualizations, proceed¬
ing from the more fundamental onward (see page 599).
The earth in igneous fusion had no more distinction of parts
than a germ. Afterwards, the continents, while still beneath the
waters, began to take shape. Then, as the seas deepened, the first
dry land appeared, low, barren, and lifeless. Under slow intestine
movements and the concurrent action of the enveloping waters,
the dry land expanded, strata formed, and, as these processes
went on, mountains by degrees rose, each in its appointed place.
Finally, in the last stage of the development, the Alps, Pyrenees,
and other heights received their majestic dimensions, and the con¬
tinents were finished to their very borders.
Again, as to the history of fresh waters. The first waters were
all salt, and the oceans one, the waters sweeping around the
sphere in an almost unbroken tide. Fresh waters left their mark
only in a rain-drop impression. Then the rising lands commenced
to mark out the great seas, and the incipient continents were at
times spread with fresh-water marshes, into which rills were flowing
from the slopes around. As the mountains enlarged, the rills
changed to rivers, till at last the rivers also were of majestic ex¬
tent, and the continents were throughout covered with streams
at work channelling mountains, spreading out plains, opening lines
of communication, and distributing fertility everywhere.
Again, the first climates were all tropical. But, when mountains
and streams were attaining their growth, a diversity of climate
(essential to the full strength of the latter) was gradually evolved,
until winter had settled about the poles as well as the earth's
loftier summits, leaving only a limited zone—and that with many
variations—to perpetual summer.
The organic history of the earth, from its primal simplicity to
740
DYNAMICAL GEOLOGY.
the final diversity, has been shown to exemplify in many ways the
same great principle.
Thus the earth's features and functions were successively indivi¬
dualized,—first the more fundamental qualities being evolved, and
finally those myriad details in which its special characteristics, its
magnificent perfection, and its great purpose of existence and fit¬
ness for duty, largely consist.
Conclusion.—The causes of the earth's movements which have
been considered appear to explain the evolution of the prominent
features of the globe; and the special history made out for North
America may be safely regarded as an example of what will here¬
after be accomplished for all the continents.
But Geology, while reaching so deeply into the origin of things,
leaves wholly unexplained the creation of matter, life, and spirit,
and that spiritual element which pervades the whole history like a
prophecy, becoming more and more clearly pronounced with the
progressing ages, and having its consummation and fulfilment in
Man. It gives no cause for the arrangement of the continents
together in one hemisphere (p. 10) and mainly in the same tem¬
perate zone, or their situation about the narrow Atlantic, with the
barrier-mountains in the remote west of America and in the remote
east of Europe and Asia, thus gathering the civilized world into one
vast arena (p. 29); it does not account for the oceans having that
exact relation in extent and depth to the land which, under all
the changes, allowed of submergence and emergence through small
oscillations of the crust, and hence permitted the spreading out
of sandstones and shales by the waves and currents, the building
up of limestones through animal life, and the accumulation of coal
beds through the growth of plants,—and all in numberless alterna¬
tions ; nor for the various adaptations of the system of plants and
animals to the wants of the last species in that system. Through
the whole history of the globe there was a shaping, provisioning,
and exalting of the earth with reference to a being of mind, to be
sustained, educated, exalted. This is the spiritual element in geo¬
logical history, for which attraction, water, and fire have no ex¬
planation.
COSMOGONY.
The science of cosmogony treats of the history of creation.
Geology comprises that later portion of the history which is
within the range of direct investigation, beginning with the rock-
covered globe, and gathering only a few hints as to a previous state
of igneous fluidity.
Through Astronomy our knowledge of this earlier state becomes
less doubtful, and we even discover evidence of a period still more
remote. Ascertaining thence that the sun of our system is. in
intense ignition, that the moon, the earth's satellite, was once a
globe of fire, but is now cooled and covered with extinct craters,
and that space is filled with burning suns,—and learning also from
physical science that all heated bodies in space must have been
losing heat through past time, the smallest most rapidly,—we safely
conclude that the earth has passed through a stage of igneous
fluidity.
Again, as to the remoter period: the forms of the nebulas and
of other starry systems in the heavens, and the relations which
subsist between the spheres in our own system, have been found to
be such as would have resulted if the whole universe had been
evolved from an original nebula or gaseous fluid. It is not neces¬
sary for the strength of this argument that any portion of the
primal nebula should exist now at this late period in the history of
the universe: it is only what might have been expected that the
nebulae of the present heavens should be turning out to be clusters
of stars. If, then, this nebular theory be true, the universe has
been developed from a primal unit, and the earth is one of the
individual orbs produced in the course of its evolution. Its his¬
tory is in kind like that which has been deciphered with regard to
the earth: it only carries the action of physical forces, under a
sustaining and directing hand, further back in time.
The science also of Chemistry is aiding in the study of the earth's
earliest development, and is preparing itself to write a history of
the various changes which should have taken place among the
elements from the first commencement of combination to the
formation of the solid crust of our globe.
It is not proposed to enter either into chemical or astronomical
741
742
COSMOGONY.
details in this place, but, supposing the nebular theory to be true,
briefly to mention the great stages of progress in the history of the
earth, or those successive periods which stand out prominently in
time through the exhibition of some new idea in the grand system
of progress. The views here offered, and the following on the cos¬
mogony of the Bible, are essentially those brought out by Professor
Guyot in his lectures.
Stages of progress.—These stages of progress are as follow :—
(1.) The beginning of activity in matter.—In such a beginning
from matter in the state of a gaseous fluid the activity would be
intense, and it would show itself at once by a manifestation of light,
since light is a resultant of molecular activity. A flash of light
through the universe would therefore be the first announcement
of the work begun.
(2.) The development of the earth.—A dividing and subdividing of
the original fluid going on would have evolved systems of various
grades, and ultimately the orbs of space, among these the earth,
an igneous sphere enveloped in vapors.
(3.) The production of the earth's physical features,—by the out¬
lining of the continents and oceans. The condensible vapors would
have gradually settled upon the earth as cooling progressed.
(4.) The introduction of Life under its simplest forms,—as in the
lowest of plants, and perhaps, also, of animals. As shown on page
396, the systems of structure characterizing the two kingdoms of
nature, the Radiate of the Vegetable kingdom, and the Radiate, Mol-
luscan, Articulate, and Vertebrate of the Animal, are not brought out
in the simplest forms of life. The true Zoic era in history began
later. As plants are primarily the food of animals, there is reason
for believing that the idea of life was first expressed in a plant.
(5.) The display of the Systems in the Kingdoms of Life,—the exhi¬
bition of the four grand types under the Animal kingdom, being
the predominant idea in this phase of progress.
(6.) The introduction of the highest class of Vertebrates,—that of the
Mammals (the class to which Man belongs),—viviparous species,
which are eminent above all other Vertebrates for a quality pro¬
phetic of a high moral purpose,—that of suckling their young.
(7.) The introduction of Man,—the first being of moral and intel¬
lectual qualities, and one in whom the unity of nature has its full
expression.
There is another great event in the Earth's history which has
not yet been mentioned, because of a little uncertainty with regard to
its exact place among the others. The event referred to is the first
shining of the sun upon the earth, after the vapors which till
COSMOGONY.
743
then had shrouded the sphere were mostly condensed. This must
have preceded the introduction of the Animal system, since the sun
is the grand source of activity throughout nature on the earth,
and is essential to the existence of life, excepting its lowest forms.
In the history of the globe which has been given on page 196, it
has been shown that the outlining of the continents was one of the
earliest events, dating even from the Azoic age ; and it is probable,
from the facts stated, that it preceded that clearing of the atmo¬
sphere which opened the sky to the earth. This would place the
event between numbers 3 and 5, and, as the sun's light was not
essential to the earliest of organisms, probably after number 4.
The order will, then, be—
(1.) Activity begun,—light an immediate result.
(2.) The earth made an independent sphere.
(3.) Outlining of the land and water, determining the earth's
general configuration.
(4.) The idea of life expressed in the lowest plants, and after¬
wards, if not cotemporaneously, in the lowest or systemless ani¬
mals, or Protozoans.
(5.) The energizing light of the sun shining on the earth,—an
essential preliminary to the display of the systems of life.
(6.) Introduction of the systems of life.
(7.) Introduction of Mammals,—the highest order of Vertebi'ates,
—the class afterwards to be dignified by including a being of moral
and intellectual nature.
(8.) Introduction of Man.
Cosmogony of the Bible.—There is one ancient document on cosmo¬
gony—that of the opening page of the Bible—which is not only
admired for its sublimity, but is very generally believed to be of
divine origin, and which, therefore, demands at least a brief con¬
sideration in this place.
In the first place, it may be observed that this document, if true,
is of divine origin. For no human mind was witness of the events ;
and no such mind in the early age of the world, unless gifted with
superhuman intelligence, could have contrived such a scheme;—
would have placed the creation of the sun, the source of light to
the earth, so long after the creation of light, even on the fourth
day, and, what is equally singular, between the creation of plants
and that of animals, when so important to both ; and none could
have reached to the depths of philosophy exhibited in the whole
plan.
Again, If divine, the account must bear marks of human imperfection,
since it was communicated through man. Ideas suggested to a human
744
COSMOGONY.
mind by the Deity would take, shape in that mind according to its
range of knowledge, modes of thought, and use of language, unless
it were at the same time supernaturally gifted with the profound
knowledge and wisdom adequate to their conception; and even
then they could not be intelligibly expressed, for want of words to
represent them.
The central thought of each step in the Scripture cosmogony—
for example, Light,—the dividing of the fluid earth from the fluid
around it, individualizing the earth,—the arrangement of its land
and water,—vegetation,—and so on—is brought out in the simple
and natural style of a sublime intellect, wise for its times, but un¬
versed in the depths of science which the future was to reveal.
The idea of vegetation to such a one would be vegetation as he
knew it; and so it is described. The idea of dividing the earth
from the fluid around it would take the form of a dividing from
the fluid above, in the imperfect conceptions of a mind unac¬
quainted with the earth's sphericity and the true nature of the
firmament,—especially as the event was beyond the reach of all
ordinary thought.
Objections are often made to the word " day,"—as if its use limited the time
of each of the six periods to a day of twenty-four hours. But in the course
of the document this word "day" has various significations, and, among them,
all that are common to it in ordinary language. These are—(1) The light,—
" God called the light day," v. 5; (2) the " evening and the morning" before
the appearance of the sun ; (3) the " evening and the morning" after the ap¬
pearance of the sun; (4) the hours of light in the twenty-four hours (as well as
the whole twenty-four hours), in verse 14; and (5) in the following chapter, at
the commencement of another record of creation, the whole period of creation
is called "a day." The proper meaning of "evening and morning," in a history
of creation, is beginning and completion; and, in this sense, darkness before
light is but a common metaphor.
A Deity working in creation like a day-laborer by earth-days of twenty-four
hours, resting at night, is a belittling conception, and one probably never in the
mind of the sacred penman. In the plan of an infinite God, centuries are
required for the maturing of some of the plants with which the earth is
adorned.
The order of events in the Scripture cosmogony corresponds
essentially with that which has been given. There was first a void
and formless earth: this was literally true of the "heavens and
the earth," if they were in the condition of a gaseous fluid. The
succession is as follows :—
(1.) Light.
(2.) The dividing of the waters below from the waters above the
earth (the word translated waters may mean fluid).
COSMOGONY.
745
(3.) The dividing of the land and water on the earth.
(4.) Vegetation; which Moses, appreciating the philosophical
characteristic of the new creation distinguishing it from previous
inorganic substances, defines as that "which has seed in itself."
(5.) The sun, moon, and stars.
(6.) The lower animals, those that swarm in the waters, and the
creeping and flying species of the land.
(7.) Beasts of prey ("creeping" here meaning "prowling").
(8.) Man.
In this succession, we observe not merely an order of events, like
that deduced from science ; there is a system in the arrangement,
and a far-reaching prophecy, to which philosophy could not have
attained, however instructed.
The account recognizes in creation two great eras of three days
each,—an Inorganic and an Organic.
Each of these eras opens with the appearance of light: the first,
light cosmical; the second, light from the sun for the special uses of
the earth.
Each era ends in a " day" of two great works,—the two shown
to be distinct by being severally pronounced "good." On the
third "day," that closing the Inorganic era, there was first the
dividing of the land from the ivaters, and afterwards the creation of vege¬
tation, or the institution of a kingdom of life,—a work widely
diverse from all preceding it in the era. So on the sixth " day,"
terminating the Organic era, there was first the creation of Mammals-,
and then a second far greater work, totally new in its grandest
element, the creation of Man.
The arrangement is, then, as follows:—
1. The Inorganic Era.
1st Day.—LIGHT cosmical.
2d Day.—The earth divided from the fluid around it, or indivi¬
dualized.
f 1. Outlining of the land and water.
1 2. Creation of vegetation.
2. The Organic Era.
4th Day.—LIGHT from the sun.
5th Day.—Creation of the lower orders of animals.
-r, f 1- Creation of Mammals.
6th Day. j ^ Creation of Man.
In addition, the last day of each era included one work typical
of the era, and another related to it in essential points, but also
746
COSMOGONY.
prophetic of the future. Vegetation, while, for physical reasons, a
part of the creation of the third day, was also prophetic of the
future Organic era, in which the progress of life was the grand cha¬
racteristic. The record thus accords with the fundamental princi¬
ple in history that the characteristic of an age has its beginnings
within the age preceding. So, again, Man, while like other Mammals
in structure, even to the homologies of every bone and muscle, was
endowed with a spiritual nature, which looked forward to another
era, that of spiritual existence. The seventh " day," the day of rest
from the work of creation, is man's period of preparation for that
new existence; and it is to promote this special end that—in strict
parallelism—the Sabbath follows man's six days of work.
The record in the Bible is, therefore, profoundly philosophical in
the scheme of creation which it presents. It is both true and
divine. It is a declaration of authorship, both of Creation and the
Bible, on the first page of the sacred volume.
There can be no real conflict between the two Books of the
Great Author. Both are revelations made by Iiim to man,—the
earlier telling of God-made harmonies coming up from the deep
past, and rising to their height when man appeared, the later
teaching man's relations to his Maker, and speaking of loftier har¬
monies in the eternal future.
APPENDIX.
A.—Animal Kingdom (p. 147).
1. Distinctions between Animals and Plants.—Since the discovery that the
spores (or seed-cells) of some Algm have locomotion like animalcules, and that
there are unicellular locomotive plants (the Diatoms, etc.), some have thought
that the two kingdoms of life blended together through their inferior species.
But the fact is that they are diverse throughout,—the opposite but mutually
dependent sides or parts of one system of life. The following are some of
their distinctions :—
(1.) Plants excrete oxygen, a gas essential to animal life; animals excrete in
respiration carbonic acid, a gas essential to vegetable life.
(2.) Plants take inorganic material as food, and turn it into organic; animals
take this organic material thus prepared (plants), or other organic materials
made from it (animals), finding no nutriment in inorganic matter.
(3.) Plants in passing from the unicellular state by growth lose in power, be¬
coming usually fixed. Animals, in the same change, or in development from a
germ, increase in power, augmenting in muscular force, and also, in the case of
species above the lowest grade, in nervous force,—until an ant, for example,
becomes a one-ant power, a horse a one-horse power; whence an animal is a self-
propagating piece of enginery of various power according to the species.
(4.) The Vegetable kingdom is a provision for the storing away or magazining
of force for the Animal kingdom. This force is acquired through the sun's in¬
fluence or forces acting on the plant, and so promoting growth; mineral matter
is thereby carried up to a higher grade of composition, that of starch, vegetable
fibre, and sugar, and this is a state of concentrated or accumulated force. To
this stored force animals go in order to carry forward their development; and,
moreover, the grade of composition thus rises still higher to muscle and nerve
(which contain nitrogen in addition to the constituents of the plant), and this is a
magazining of force in a still more concentrated or condensed state. There are
thus five states of stored force in nature,—three in inorganic, the solid, liquid,
and gaseous; and two in organic, the vegetable and animal.®
The Animal type differs from the Vegetable (though not all animals from
plants) in this: that, while the latter has the superior-and-inferior polarity of
simple growth,—the stem growing upward and the root downward,—the former
* From a paper by the author on the " Anticipations of Man in Nature," published in the
New Englander, May, 1809.
747
748
APPENDIX.
has the anterior-and-posterior, or cephalic and anti-eephalic, polarity, connected
with a well-developed nervous system. The Radiates among animals are allied
in this respect to plants, being Animal representatives of the Vegetable radiate
type; and this is the ground of the subdivision of the Animal kingdom stated
on page 596 (§ c). Among the Radiates, the Polyps (the lowest of the three
classes), in their modern and more typical kinds (see Appendix F), have a six-
rayed structure, the Acalephs a four-rayed, the Echinoderms (or highest) a
five-rayed; and these last look forward through their many unsymmetrical forms
towards the cephalic polarity of the other sub-kingdoms.
2. Protozoans.—The two most common, and geologically the most important,
subdivisions of the Protozoans, are mentioned on page 163. A few remarks on
the classification of the group are added.
The Protozoans include those minute animal species in which neither of the
four grand systems of the Animal kingdom (the Radiate, Molluscan, Articulate,
and Vertebrate) is distinctly brought out. They represent life simply, or sys-
temless. Their analogues among plants are the Ahjx, which are also systemless ;
that is, are without the radiate structure typical of the Vegetable kingdom.
Protophytes are only microscopic Algae.
Although the grand systems in Zoology are unpronounced, there are still faint
indications of them generally observable, or to be inferred from resemblances to
the embryonic condition of higher species, and these are the most fundamental
distinctions for their arrangement. The groups accordingly appear to be the
following:—
• 1. ActinozoOids ; or, Jiadiate Protozoans, as the Sponges, Polycystines, Noc-
tilucae, etc. The mineral secretions, when any exist, are, with few exceptions,
siliceous. (A few sponges have calcareous spicula.)
A few species are here figured. Fig. 976 represents a Spherozoum (S. orien-
tale D.), a gelatine-like spheroidal mass, containing many minute circular spots,
each set about with siliceous spicula (see Amer. Jour. Sci. [2] xxxv.). Fig. 979 a
is the mass, natural size, and b one of the circular spots or individuals of the
Protozoans.—Fig. 979 a, Spherozoum orientale, natural size; b, one of the individuals in
the compound mass enlarged; 980, Lychnocanium Lucerna (X 100); 9S1, Eucyrtidium
Mongolfieri (X 100); 9S2, Halicalyptra fimbriata (X 75).
Fig. 979.
Figs. 980-982.
81
compound mass, enlarged. This species was obtained by the author in the Pacific
in lat. 28° to 30° N., long. 17S° W., where they were so abundant as to make
the water look cloudy. The Spherozoa are supposed to be closely related to
APPENDIX.
749
sponges. It is possible that the spicula of allied species may hare contributed
to deep-sea formations in ancient oceans. (See figs./, I, m, p. 271.)
Figs. 980-982 are of Polycystines from the Barbadoes (p. 612); fig. 980,
Lychnocanium Lucerna Ehr.; fig. 981, Eucyrtidium Mon<jo{fieri Ehr.; fig. 982,
Halicalyptra fimbriata Ehr., the first two magnified 100 diameters, the last about
75. From these deeply concave forms there are gradations in one direction to
disks with concave centres, and to flat disks, both with plain and pointed borders,
and in the other direction to elongate, conical, and spindle-shaped forms.
Others have the shape of a flattened cross; another is an open diamond with
narrow diagonals and periphery. The disks have a concentric, and not a spiral,
structure, and thus are unlike those of Nummulites. For figures, see Ehren-
berg's Mikrogeologie, and Bailey in Amer. Jour. Sci. [2] xxii. pi. 1.
The living Polycystines extend out fibre-like processes through pores in the
shells, and in this respect are like Rhizopods.
Although probably among the earliest kinds of life, Polycystines have not
yet been recognized in rocks below the Tertiary, unless an ovoidal siliceous cell
found by M. C. White in the chert of the Black River limestone of Watertown,
N.Y. (Amer. Jour. Sci. [2] xxxiii. 386, fig. 30), is of this nature.
2. Malacozooids ; or, Mollusk-like Protozoans, as the Rhizopods. The mine¬
ral secretions, when there are any, are calcareous, and the cells are arranged
alternately or spirally (p. 164), in this resembling the Bryozoans and Gastero-
pods among Mollusks.
D'Orbigny's classification of the Rhizopods, given on page 164, is not a natural
one; and none has yet been proposed that is free from objections.
3. Entomozooids ; or, Articulate-like Protozoans.
The Infusoria that are not plants nor larval forms of higher species belong
to one of these three divisions. According to Agassiz, the Vorticella group is
related to the Bryozoans among Mollusks. Other Infusoria, as the unsymme-
trical Trachelocercx, Plesconiee, etc., may be also Mollusk-like forms. Many of
the symmetrical Infusoria have been proved to be only the embryonic condition
of worms; but some so related will probably prove to be true Entomozooids.
The Amcebx, as has been suggested, may be. larval, as is now known to be the
case with the Gregarinidx.
The geological importance of Rhizopods has already been explained, except¬
ing in one respect,—their connection with the origin of Green-sand, a fact first
observed by Ehrenberg. The Green-sand grains of the Cretaceous and other
formations are found to be very generally casts of these shells. The material
first forms within them, and then penetrates all the pores of the minute structure,
and finally, on the disappearance of the carbonate of lime, it has their interior
or exterior form. Bailey found this same green earth (glauconite) filling recent
Rhizopod shells from the Gulf of Mexico, and from the bottom of the Atlantic
beneath the Gulf Stream and in other parts; and Pourtales has since made the
same observation. The latter states, however, that he found this green earth
penetrating also the shells of some small JTollusks, Barnacles, and Millepore
Corals. No chemical explanation of these facts has yet been offered. (Bailey,
Amer. Jour. Sci. [2] xxii. 282; Pourtales, Rep. Coast Survey, 1859, 248.)
750
APPENDIX.
B.—Hudson Period (p. 217).
The Lorraine shales (designated in part Pulaski shales in the N.Y. Annual
Geological Reports) were so named from the town of Lorraine, in the southern
part of Jefferson co., N.Y., where the whole thickness of the beds overlying the
ITtica shales is well exposed. They include the western part of the Hudson
River formation in the State of New York. They consist of thin beds of gray
sandstone, alternating with fine argillaceous shales. The beds are in general
nearly horizontal; they extend eastward along the Mohawk valley.
Although the Hudson River formation has lost a large part of its strata in
the Hudson River valley by the discovery that the upturned slates of that
region are of the Potsdam period, it still retains some portions on the west side
of the river, enough to render it proper to continue to use the name for the
formation and for the period to which it belongs. The name is now so much
a part of the science in Europe, as well as in America, that any change is greatly
to be deprecated.
C.—Devonian Age.
According to E. Jewett, recent observations, both stratigraphical and palajon-
tological, by himself and J. M. Way, in Delaware co., N.Y., tend to prove that
the rocks of the so-called Catskill group are probably all Chemung. Several
fossils from distant localities have been identified with Chemung species.
Figure 983 represents in outline, half the natural size, a portion of a fossil
plant from the Chemung beds, found at Wisner's quarry near Elmira, Chemung
co., N.Y'.,—the Lepidodendron Chemwajense D. (Sigillaria Chemungensis Hall).
The specimen figured by Hall was 12 J inches long, and from 2 inches to wide.
Fig. 984.
Figure 984 is a peculiar plant, a little like the Noeggerathise in habit, figured
by II. D. Rogers on Plato 22 of the Geological Report of Pennsylvania. On
the plate it is stated that it is a fossil plant from the Ponent sandstone beds, or
of the Catskill period. There is no reference to it in the text. Dawson suggests
that it may be identical with his Cyclopteris Brownii, a species occurring in the
Devonian of Perry, Maine.
The figure of the Noeggerathia on page 291 is from a portion of a very large
frond on limestone, found at Montrose, Pa., by Rev. H. A. Riley.
APPENDIX.
751
D. Carboniferous Period (p. 349).
The annexed figure (Fig. 985) represents, twice the natural size, a Neuropterous
Tnsect, the iliamia Bronsoni D., (Silliman's Jour., xxxvii. 34, 1864,) found by
Fig. 985.
J. G. Bronson in an iron-stone concretion at Morris, Illinois. Other concretions
of the same bed contain coal-plants, and some have afforded Amphipod Crusta¬
ceans. The anterior feet appear to have been grasping or prehensile feet, as in
the Mantispids. The large joint was armed with long slender spines.
E. Jurassic Period (pp. 453 and 462).
The newly-discovered long-tailed or reptilian Bird of Solenhofen—Archceopteryx
macrurus Owen—is represented on the following page, reduced to one-fourth,
from a plate in the Intellectual Observer for December, 1862 (London). The tail
is 11 inches long, and 3£ inches broad. It consists of 20 vertebrm, and has a row
of feathers along the sides. These feathers are in pairs corresponding with the
number of the vertebrae, and diverge from the axis at an angle of 45°; the last
pair extends backward nearly in a line with the last vertebra, and 3£ inches be¬
yond it. The wing appears to have had a two-jointed finger. The breadth of the
wing was made by feathers as in Birds, and not, as in a Pterodactyl, by an ex¬
panded membrane. The feet are like those of Birds.
In the Reptilian age, nearly all the Vertebrates had some reptilian features;
and the Birds were no exception. As the Palasozoic Ganoids had vertebrated
tail-fins, so the earliest of Birds had long vertebrated tails. They are interme¬
diate between modern Birds and the inferior class, Reptiles, just as Amphybian
Reptiles are so between true Reptiles and Fishes, and Marsupial Mammals be¬
tween ordinary Mammals and the oviparous Vertebrates.
752
appendix.
Fig. 986.
Archseopteryx macrurus.
APPENDIX.
753
F.—Glacial Epoch (p. 535).
Glacial scratches occur in Pennsylvania on tho top of Penobscot Knob, 3000
feet above the sea-level, and on Peter's Mountain, near Ilarrisburg, 2000 feet.
On the former, where they cover a naked face of rock at the extreme summit,
three sets of scratches cross each other, diverging at angles of 25 and 30 degrees.
On Peter's Mountain, horizontal scratches occur at the summit on the upright
wall of a notch in the rock thirty or forty feet deep (Lesley).
In the valley of Wyoming, Pa., there is a conformity between the direction
of the scratches and the course of the valley (II. D. Rogers).
On Catskill Mountain, N.Y., according to Ramsay, the scratches arc nume¬
rous, and continue up to the plateau on which tho hotel stands, 2850 feet above
the sea; and all but a few of the highest run from north to south along tho
flanks of the escarpment, or in the direction of the Hudson River valley, and
not from west to east down the slope of the hill. The chief grooves run between
S. 22° E. and S. 55° IV.; among them one runs S. 22° E., two S. 10° E., two
N. and S., one S. 10° W., six S. 22° W., one S. 30° AY., two S. 55° IV., one W.
10° N. Ramsay observes that the variations seem connected with bends and
other irregularities in the face of the great escarpment. The course S. 55° AY.
was found at the top, near the hotel; and in the plateau on the summit of the
water-shed there are "numerous main grooves passing across tho hill at right
angles to most of those observed during the ascent" (Quart. Jour. Geol. Soc., xv.
209).
See further, for information on scratches in New York, a tabic by Mather, in
his New York Geological Report, pages 199-200.
AY. B. Dwight, in a recent communication to the author, mentions that at
Cherry A^alley, N.Y., there are two systems of scratches, nearly at right angles
to each other, and none between the two: the directions arc (1) S.S.A\r. to S. by
E. and (2) E. by N. These courses, as he says, do not follow the slopes of the
minor valleys of the region ; but they do appe.ir to correspond to the grander
slopes of the land. Tho town lies near the summit-level, in the vicinity of the
head-waters of the Susquehanna, and also on the south border of the Mohawk
valley; and he suggests, with good reason, that one system is that of a great
glacier moving southward along the wide Susquehanna slope of the plateau of
southern New York, and the other system that of a glacier moving eastward down
the Mohawk valley. The latter probably had its independent movement when
the Glacial epoch was on the decline.
These interesting observations sustain the conclusion that the features of the
land have guided the courses of the great glaciers. On page 544, evidence has
been stated as to a Connecticut-ralley glacier and a Hudson-valley glacier, and,
also, on page 545, of a Penobscot-Bay glacier ; and now we have evidence of a
Susquehanna-valley glacier and a Mohawk-valley glacier. The absence of gla¬
cier-phenomena about many of the heights bounding the Hudson and Connec¬
ticut valleys, and the irregularity in the courses of scratches about those other
summits on which they occur, serve to define the outline of tho independent, or
partly independent, glacier-streams.
In Missouri, unstratified Drift of the Glacial epoch abounds north of the
49
754
APPENDIX.
Missouri River, and exists in small quantities as far south as the Osage and
Meramec : the thickness is from one to forty-five feet; the greatest thickness
and coarsest material are to the north. The boulders or rounded stones consist
of metamorphic rocks and fossiliferous limestone; the nearest locality of the
former in place, according to Owen, is on the St. Peter's River, about 300 miles
north of St. Joseph; the latter are from localities near where they occur, as is
shown by the fossils. The largest boulders are five to six feet in diameter. The
Drift is underlaid in several counties (and perhaps generally) by a layer of pipe¬
clay, one to six feet thick (Swallow).
There is no Drift in Arkansas, except that of a local origin (D. D. Owen).
With regard to oblique scratches up and down declivities, Professor Guyot
states, in a letter to the author, that they are a common result of glacier-action
in Switzerland. The most of the scratches on the Jura Mountains are of this
description. As the great glacier of the Rhone moved against their sides and
became deflected thereby, there was, as a resultant (on the northeast side at
least), a running up obliquely of the whole mass at the same time that it moved
eastward and down the general slope of the country.
To appreciate the effects of a vast glacier over a continent or occupying the
whole breadth of a wide valley,—like that of the Hudson between the summit
of the Green Mountains on one side and that of the Catskills on the other,—it
must be remembered that a general southerly movement in the whole mass
would carry the boulders and scratch surfaces, transversely or obliquely, across
subordinate transverse valleys and ridges, ascending or descending declivities.
It is to be noted, in connection with this subject, that powerful torrents flow
for some distance beneath all glaciers, and from their terminations; and the
effects of such torrents are naturally mingled with true glacial effects.
Agassiz and Guyot, of Switzerland, who are familiar with glaciers and the
drift, support the Glacier theory. The former first announced it in 1837.
G—Coral Reefs (pp. 587, 591).
1. Rate of growth of corals.—The author is indebted to Captain E. B. Hunt,
U.S. Engineers, for the following definite facts with regard to the rate of growth
of species at Key West, southwest of the southern cape of Florida.
Over a bottom in ten feet water which had been cleared in 1846, a Meandrina
grew in the course of eleven years to a hemisphere (the usual form of the spe¬
cies) six inches in radius.
This is equivalent to six-elevenths of an inch a year; and, allowing one-third
for the porosity of the coral, it corresponds to an upward increase in solid bulk
of four-elevenths of an inch,—which is almost identical with the three-eighths
deduced on page 691.
An Oculina—a branching coral growing in clumps—grew at the same place, in
twelve years, to a height of nine inches and a breadth of twelve inches, equiva¬
lent to three-fourths of an inch a year. This coral has few pores; but the
branches are small, being hardly a fourth of an inch thick at the extremity, and
the spaces between them are from one to one and a half inches. The amount
of increase is not equal to that of the Meandrina.
2. Florida reefs.—The rock of the reef at Key West is mainly an oolitic lime-
APPENDIX.
755
stone, usually a little friable and in some parts becoming brccciated. It forms
just above the water-level, and also below the surface to a depth of several—per¬
haps many—feet. This variety of rock is uncommon among the extensive reefs
of the Pacific, the kind most approaching it being a sea-shore rock made from
coral sands. The rock there formed from coral mud or sand at moderate depths
in the lagoon and off shore is a white, compact, unfossiliferous limestone, having
the flint-like fracture of the Bird's-eye limestone (of the Trenton period) in
central New York (p. 206).
The origin of the long curving line of coral reef stretching southwestward
from southern Florida to the Tortugas, and having a total length of 120 'miles,
has been satisfactorily explained by Captain Hunt, who attributes the prolon¬
gation to the transportation of coral sands from the coral reef to the eastward
by the Labrador current (p. 657). He shows that the current is just such as
would produce the form presented by the reef. This barrier-reef has, therefore,
the same origin as those of siliceous sands farther north on the American coast.
The only difference is this : that the material of which the sand of the coral reef
is made is a result of the growth of animal life on an earlier part of the reef.
The sound between the reef and Florida is about 120 feet deep, and has a bottom
of clean coral sand, the material of which, as Captain Hunt shows, is washed
from the reef. It is still possible that a subsidence has aided in producing the
results.
3. Soundings near coral islands.—Among the Paumotus, according to Wilkes,
southeast of Ahii, the lead struck at 150 fathoms, and then fell off, and finally
brought up at 300 fathoms; 2 miles east of Serle's Island, no bottom was found
at 600 fathoms; 1J miles south of the larger Disappointment Island, no bottom
at 550 fathoms; a mile from the east end of Metia, no bottom at 600 fathoms.
Off Whitsunday Island, Beechey found no bottom at 250 fathoms. Darwin
states that Lieut. Powell found, 600 feet from Diego Garcia, no bottom with 150
fathoms; that at Cardoo Atoll Island, 300 feet off, no bottom was obtained at
200 fathoms; 2200 yards from Keeling Island, Fitzroy found no bottom at 1200
fathoms; but the line at a depth between 500 and 600 fathoms was partly cut,
as if it had rubbed against a projecting ledge of rock.
These facts bear on the question of the thickness of coral reefs.
4. Chalk.—The only locality of chalk among the Pacific coral-reef rocks, ob¬
served by the author, occurs on the island of Oahu (Hawaian group). It has
but a few yards of extent, and is situated close by an injected dike of lava;
and it is probable that it owes its origin in some way to heat connected with
the injection. The author regards it, therefore, as no true exception to the state¬
ment made on page 617 that chalk is not one of the varieties of coral rock: it
is made by accumulations of Rhizopod shells, and not of coral or shell sand.
H.—Progress of Life (pp. 596, 597).
Dividing the Animal kingdom into Invertebrates and Vertebrates as the
two subdivisions, the Cephalopods (Orthocerata, etc.) may perhaps be regarded
as the comprehensive type, foreshadowing the latter, as explained on page
397.
The internal bone in Cephalopods, mentioned on p. 397, exists only in those
756
APPENDIX.
species that have no external shell. The earliest of this kind were probably the
Conularias, as already stated.
Page 597.—In the sub-kingdom of Radiates there are two comprehensive
types intermediate between the classes of Polyps (the inferior) and Acalephs
(the next hit/her). (1.) That of the Cyathophylloid corals, whose fundamental
structure is based on the number 4, the number eminently characteristic of Aca¬
lephs, the rays being multiples of four, and not (as in modern corals) of six.
(2.) That of the Faoosites family of corals, which, if related to modern Mille-
pores and true Acalephs, as Agassiz holds (p. 162), belong to that division of
Acalephs which embraces species so polyp-like that until recently they wero
arranged with Polyps. The species of these comprehensive types are the only
known representatives of Polyps and Acalephs in the Palmozoic faunas, except¬
ing possibly the Graptolites; and these, if Acalephs (p. 190), are Ilydroids like
the Favositcs.
Coral-making Mollusks (Bryozoans), Polyps, and Acalephs, were a prominent
part of that harmonious assemblage of groups which constituted the life of the
Palmozoic.
L.—Mineral Oil.
Mineral Oil, or Petroleum, is a bituminous liquid resulting from the decom¬
position of marine or land plants (mainly the latter), and perhaps, also, of some
non-nitrogenous animal tissues. It proceeds from rocks of various ages, from
the Lower Silurian to the Post-tertiary, and from limestones and sandstones, as
well as shales. The so-called anthracite of the Calciferous beds of New York is,
according to T. S. Hunt, an altered and inspissated mineral oil; and liquid drops
of the original material sometimes exist in the quartz crystals of the same region.
In the Bird's-eye limestone of Riviere a la Rose (Montmorenci), Canada, and of
Watertown, N.Y., it flows in drops from a fossil coral; and in the Trenton lime¬
stone at Pakenham, Canada, it fills the cavities of large Orthocerata. It pro¬
ceeds from the Hudson River formation in Guelderland, near Albany, and occurs
on the surface of a spring and issues from the Utica slate on Great Manitoulin
Island (Lake Huron). The Niagara limestone sometimes affords traces of it;
and so also do the Medina red shales.
The Corniferous beds of the Devonian afford petroleum at Black Rock in the
Niagara River, where it occupies cavities in fossils; and, in sufficient abundance
to be an object of commerce, at Enniskillen in Western Canada, near which place
there is, over the surface, a deposit of solid bitumen or mineral tar, half an acre
in extent, probably derived from the limestone beds below.
The Marcellus shales, or lower part of the Hamilton group, and also the upper
part of the same, contain occasionally concretions which enclose petroleum.
The rocks of the Chemung period afford abundant oil-springs in Erie, Seneca,
and Cattaraugus counties, New York. The oil-wells of Pennsylvania and Ohio
are sunk in Devonian or Subcarboniferous sandstones, often descending through
overlying Carboniferous strata. Some of the most noted " wells" in these
regions are at Mecca in Trumbull co., Ohio, Titusville on Oil Creek in Penn¬
sylvania, and near the Little Kanawha in Virginia.
In the American Mcsozoic, a liquid petroleum occurs in Triassic shales ana
limestone at Southbury, Ct.
APPENDIX.
757
The petroleum of the island of Trinidad arises from the Tertiary formation.
Mineral oil is a compound of hydrogen and carbon. The composition varies
between C^II^, and C^ILy. In becoming inspissated it is often more or less
oxydized, losing sometimes in part its fusibility and its solubility in ether.
"See further, on this subject, a paper by E. B. Andrews in the Aincr. Jour. Sci.
[2] xxxii. S5, and one by T. S. Hunt in the Canadian Naturalist and Geologist,
vi. 241, August, 1S61, from which the larger part of the above facts have been
cited.
J.—Catalogue of American Localities of Fossils.
The following catalogue of American localities of fossils contains only some
of the more important, and is intended for the convenience especially of the stu¬
dent-collector.
Localities of Fossils.
Potsdam sandstone.—Swanton, Vt.; Braintrce, Mass.; Kccscvillc (at " High
Bridge"), Alexandria, N.Y.; Chiqucs Ridge, Pa.; Falls of St. Croix, Osceola
Mills, Trcmpaleau, Wisconsin; Lansing, Iowa; St. Ann's, Isle Pcrrot, C.W.; near
Beauharnois on Lake St. Louis, C.E.
Calcifcrous.—Point Levi, Mingan Islands, Philipsburg, and near Beauharnois,
C.E.; Grand Trunk Railway between Brockville and Prescott, St. Ann's, Isle
Pcrrot, C.W.; Amsterdam, Fort Plain, Canajoharie, Chazy, Lafargeville, Ogdens-
burgh, N.Y.
Cliazy Milestone.—Chazy, Galway, Westport, N.Y.; Island of Montreal, C.E.,
1 to 3 miles north of "the Mountain."
Bird's-eye limestone.—Amsterdam, Little Falls, Fort Plain, Adams, Water-
town, N.Y.
Black River limestone.—Watertown, N.Y.; Ottawa, C.W.; Island of Mon¬
treal, and near Quebec, C.E. •
Trenton limestone.—Adams, Watertown, Boonville, Turin, Jacksonburgh, Little
Falls, Lowville, Middleville, Fort Plain, Trenton Falls, N.Y.; Pino Grove, Aarons-
burg, Potter's Fort, Milligan's Cove, Pa.; Ilighgate Springs, Vt.; Montmorency
Falls and Beauport Quarries near Quebec, Island of Montreal (quarries N. of
the city), C.E.; Ottawa, Belleville, Trenton (G. T. R. R., W. of Kingston), C.W. ;
Copper Bay, Mich.; Elkader Mills, Turkey River, Dubuque, Iowa; Falls of St.
Anthony, St. Paul, Mineral Point, Cassville, Bcloit, Quimby's Mills near Benton,
Wis.; Warren, Illinois.
Utiea slate.—Turin, Martinsburgh, Lorraine, Worth, Utica, Cold Spring,
Oxtungo and Osquago Creeks near Fort Plain, Mohawk, Rouse's Point, N.Y.;
Rideau River along R. R. at Ottawa, bed of river two miles above, C.W.
Hudson River group.—Pulaski, Rome, Lorraine, and Boonville, N.Y.; Pcnn's
Valley, Milligan's Cove, Pa.; Oxford, Cincinnati, 0.; Madison, Ind.; Anticosti,
opposite Three Rivers, C.E.; Weston on the Ilumber River, nine miles W. of
Toronto, C.W.; Little Makoqueta River, Iowa; Savannah, Green Bay, Wis.;
Scales Mound, 111.; Druininond's Island, Mich.
Medina sandstone.—Loekport, Lcwiston, Medina, Rochester, N.Y.; Long Nar¬
rows below Lcwistown, Pa.
758
APPENDIX.
Clinton group.—Lewiston, Lockport, Reynolds' Basin, Brockport, Rochester,
Wolcott, New Hartford, N.Y.; Thorold on Welland Canal, Hamilton, Ancaster,
C.W.
Niagara.—Lewiston, Lockport, Rochester, Wolcott, N.Y.; Thorold, Hamilton,
Ancaster, C.W.; Anticosti, C.E.; Arisaig, Nova Scotia; Racine, Waukesha, Wis!;
Marblehead on Drummond's Island, Michigan. (Coralline limestone.—Scho¬
harie, N.Y.)
Onondaga Salt Group.—Buffalo, Williamsville, Waterville, Jerusalem Hill
(Herkimer co.), N.Y.
Lcclaire limestone.—Leclaire, 111.
" Gait" or " Guelph" formation.—Gait, Guelph (G. T. R. R.), C.W.
Loxoer Helderberg limestones.—Dry Hill, Jerusalem Hill (Herkimer CO.),
Sharon, East Cobleskill, Judd's Falls, Cherry Valley, Carlisle, Schoharie, Clarks-
ville, Athens, N.Y.; Gaspe, C.E.
Oriskany sandstone.—Oriskany, Vienna, Carlisle, Schoharie, Catskill Moun¬
tains, N.Y.; Cumberland, Md.; Moorestown and Frankstown, Pa.
Cauda-Galli Grit.—Schoharie (Fucoides Cauda-Galli), N.Y.
Schoharie Grit.—Schoharie, Cherry Valley, N.Y.
Upper Helderberg limestones.—Black Rock, Buffalo, Williamsville, Lancaster,
Clarence Hollow, Stafford, Le Roy, Caledonia, Mendon, Auburn, Onondaga,
Cassville, Babcock's Hill, Schoharie, Cherry Valley, Clarksville, N.Y.; Port
Colborne, and near Cayuga, C.W.; Columbus, Delaware, Sandusky, 0.; Macki¬
nac, Little Traverse Bay, Dundee, Monguagon, Mich.
Marcellus shales.—Lake Erie shore, ten miles S. of Buffalo, Lancaster, Alden,
Avon, Leroy, Marcellus, Manlius, Cherry Valley, N.Y.
Hamilton group.—Lake Erie shore, Eighteen Mile Creek, Hamburgh, Alden,
Darien, York, Moscow, Bloomfield, Bristol, Seneca Lake, Caynga Lake, and
Skaneateles Lake, Pompey, Cazcnovia, Delphi, Bridgewater, Richland, Cherry
Valley, Seward, Westford, Milford, Portlandville, N.Y.; Widden Station (G. T.
R. R.), near Port Sarnia, C.W.; New Buffalo, Independence, Iowa; Rock Island,
111.; Thunder Bay, Little Traverse Bay, Mich.; Nictaux, Bear River, Moose
River, Nova Scotia.
Genesee slate.—Banks of Seneca and Cayuga Lakes, Lodi Falls, Mount
Morris, two miles S. of Big Stream Point, Yates co., N.Y.
Portage group.—Eighteen Mile Creek, Lake Erie shore, Chautauqua Lake,
Genesee River at Portage, Flint Creek, Cashaqua Creek, Nunda, Seneca and
Cayuga Lakes, N.Y.
Chemung group.—Rockville, Philipsburgh, Jasper, Greene, Chemung Nar¬
rows, Troopsville, Elmira, Ithaca, Waverly, Hector, Enfield, N.Y.; Gaspe, C.E.
Catskill group.—Fossils rare.—Richmond's quarry above Mt. Upton on the
Unadilla, Oneonta, Oxford, Steuben co. south of the Canisteo, N.Y. ; Franklin,
Delaware co., N.Y. The fossils are Chemung.—See p. 750.
Subcarboniferous.—Burlington, Keokuk, Iowa; Quincy, Warsaw, Alton, Kas-
kaskia, Chester, 111.; Bloomington, Spergen Hill, Ind.; Hannibal, St. Genevieve,
St. Louis, Mo.; Willow Creek, Battle Creek, Holland, Grand Rapids, Mich. ;
Mauch Chunk, Pa.; Red Sulphur Springs, Pittsburg Landing, Tenn.; Big Bear
and Little Bear Creeks, Big Crippled Deer Creek, Miss.; Clarksville, Huntsville,
Ala.: Windsor, Horton, Nova Scotia.
APPENDIX.
759
Carboniferous.—South Joggins, Pictou, Sydney, Nova Scotia; Wilkesbarre,
Shamokin, Tamaqua, Pottsville, Minersville, Tremont, Greensburg, Carbondale,
Port Carbon, Lehigh, Trevorton, Johnstown, Pittsburg, Pa.; Pomeroy, Marietta,
Zanesville, Cuyahoga Falls, Athens, Ohio; Charlestown, Clarksburg, Kanawha
Salines, Wheeling, Va.; Saline Company's mines, Gallatin co., Terre Haute,
Springfield, 111.; Bell's, Casey's, and Union Mines, Crittenden co., Hawesville
and Lewisport, Hancock co., Breckinridge, Giger's Hill, Mulford's Mines, and
Thompson's Mine, Union co., Providence and Madisonville, Hopkins eo., Bon-
harbour, Daviess co., Ky.; Muscatine, Alpine Dam, Iowa; Leavenworth, In¬
dian Creek, Grasshopper Creek, Juniata, Manhattan, Kansas.
Triassic.—Southbury, Middlefield, Portland, Conn.; Turner's Falls, Sunder¬
land, Mass.; Phoenixvilld, Pa.; Richmond, Va.; Deep River and Dan River
coal fields, N.C.
Cretaceous.—Upper Freehold, Middletown, Marlboro', Blue Ball, Deal, Squan-
kum, Shark River, Monmouth co., Pemberton, Vinccnton, Burlington co.,
Blackwoodtown, Camden co., Mullica Hill, Gloucester co., Woodstown, Man-
nington, Salem co., New Egypt, Ocean co., N. J.; Warren's Mill, Itawamba co.,
Tishomingo Creek, R. R. cuts, Hare's Mill, Carrollsvillc, Tishomingo eo., Ply¬
mouth Bluff, Lowndes co., Chawalla Station (M. & C. R. R.), Ripley, Tippah co.,
Noxubee, Macon, Noxubee co., Kemper, Pontotoc and Chickasaw counties,
Miss.; Tuscaloosa, Ala. ; Fox Hills, Sage Creek, Long Lake, Great Bend, Che¬
yenne River, etc., Nebraska.
Eocene.—Everywhere in Tippah eo.; Yockeney River; New Prospect P. 0.,
Winston co.; Marion, Lauderdale co.; Enterprise, Clarke co.; Jackson ; Satartia,
Yazoo co.; Ilomewood, Scott co.; Chickasawhay River, Clarke co.; Winchester,
Red Bluff Station, Wayne co.; Vicksburg, Amsterdam, Brownsville, Warren
co.; Brandon, Byram Station, Rankin co.; Paulding, Jasper co., Miss.; Clai¬
borne, Monroe co., St. Stephen's, Washington co., Ala.; Charleston, S.C.; Tampa
Bay, Florida; Fort Washington, Fort Marlborough, Piscataway, Md.; Marl-
bourne, Va.; Brandon, Vt.; Canada dc las Uvas, Cal.
Miocene.—Gay Head, Martha's Vineyard, Mass.; Shiloh, Jericho, Cumber¬
land co., N.J.; St. Mary's, Easton, Md.; Yorktown, Suffolk, Smithfield, Rich¬
mond, Petersburg, Va.; Astoria, Willamette River, Oregon ; San Pablo Bay,
Ocoya Creek, San Diego, Monterey, San Joaquin and Tulare Valleys, Cal.;
White River, Upper Missouri Region.
Pliocene.—Ashley and Santee Rivers, S.C.; Platte and Niobrara Rivers,
Upper Missouri.
K.—Brief Synopsis of this Manual.
This synopsis is intended to serve as a basis for a short course of instruction,
such as may be desired in Institutions not strictly scientific.
I. Introduction.—Physiographic Geology.—Page 1. Distinctions between
a plant or animal and a crystal, or organic and inorganic individuals.—1, 2. In
what respects the earth is an individuality.—Of what Geology treats.—Id.
Physiography.—The earth in its relations to Man.—3. Proof of oneness of law
through space.—4. Aim of Geology.—5. Instruction from fossils and strata.
760
APPENDIX.
—7. Existing forces f.nd the ancient identical.—Subdivisions of Geology.—9.
Importance of Physiographic Geology.—10. Form of the earth.—Relative extent
of land and water.—The land in cue hemisphere.—11. General arrangement of
the oceans and continents.—Contrast in extent of the Atlantic and Pacific
oceans and Occidental and Oriental continents.—12. Oceanic depression ; its
true outline; depth.—13. Distribution of the continental areas.—14. Oceanic
islands in ranges.—15. Mean elevation cf the land.—Subdivisions of the sur¬
face of continents, with examples.—10. Average slope of Rocky Mountains.—
19. Composite nature of Mountain-chains, and variations in the positions of the
ridges along their courses.—22. General character of River-systems.—River-
systems of North America.—23. Positions of Lakes.
II. Physiographic Geology, Continued.—Page 23. First law with regard
to the reliefs of continents; Second law id.—24. How exemplified in North
America.—25. Id. in South America.—Id. in Europe and Asia.—27. Id. in
Africa.—29. Id. in Australia.—What is a Continent?—30. First and second
principles with regard to the systems of courses cf the earth's features; third
principle ; fourth ■And fifth.—Examples in the Pacific of the two systems of trends.
33. Characteristics and extent cf the Polynesian Chain.—34. Id. of the Austral¬
asian Chains.—35. Id. of the New Zealand Chain—30. Trends of the Pacific and
Atlantic oceans.—Curves on the coast cf Asia.—37. Examples of the systems of
trends in North America.—38. Id. in Asia and Europe.—39. System of oceanic
movements.—40. The main facts in the system.—Cause of movement.—41.
Examples in the Atlantic and Pacific.—42. Effect cf Oceanic currents on the
isothermal lines of the tropics (Physiographic Chart).—44. Uses of the subject
of oceanic temperature to the Geologist.—General system of Atmospheric
currents.—45. Effects of land and water on climate.—Effect of varying the
distribution of land over the globe.—4C. Laws governing the distribution of
forest-regions, prairies, and deserts.—Examples in America.—47. Cause of in¬
dividual characteristics of continents.
III. Litiioi.ogical Geology.—Page 49. Subjects treated of under Litho-
logical Geology.—A rock.—Organic constituents.—Mineral constituents.—50, 51.
Diverse qualities of the elements of organic and inorganic nature.—Charac¬
teristic elements.—51-54. Special importance of Silicon; Aluminium; Magne¬
sium; Calcium; Potassium and Sodium; Iron; Carbon.—55. Characters of
Quartz; Feldspar.—5(5. Id. of Mica.—59, CO. Id. of Hornblende, Pyroxene,
Chrysolite.—Gl. Id. of Talc; Serpentine; Chlorite.—02, 03. Id. of Calcitc, Dolo¬
mite, Gypsum.—00. Some of the materials of organic origin.—09. Changes in
fossils.—70. Definitions of fragmental, sedimentary, stratified, crystalline, ig¬
neous, metamorpliic, as applied to rocks.—73. Conglomerate; Sandstone; Shale;
Tufa; Alluvium.—75-77. Granite; Gneiss; Mica schist; Argillitc.—78. Syenite;
Hornblcndic gneiss and schist.—SI. Talcosc schist; Chloritie schist; Serpen¬
tine; Ophiolite.—83. Quartzite.—S4, 85. Limestone, massive; oolitic; chalk:
granular.—85. Gypsum.—80. Igneous rocks; feldspathic and augitic.
IV. Litiiological Geology, Continued.—Pages 90, 91. Stratified rocks.—
91. A layer; stratum; formation.—Origin of strata.—93. Massive structure;
shaly; laminated; compound ebb-and-flew and sand-drift structures.—95, 96.
Concretionary structure.—99, 100. Joints; cleavage or slaty structure.—102.
Natural positions of strata as formed.—103. Consequent principle in Geology.
APPENDIX.
701
—103, 104. Tilted or dislocated strata; folds or flexures.—105. Outcrop; dip;
strike; anticlinal; synclinal.—100. Clinometer.^-Faults.—Results of denuda¬
tion in obscuring the order of stratification.—110. Calculating thickness of
strata.—111. Unconformable strata.—112, 113. Difficulties in the way of de¬
termining the order of arrangement of strata.—113-115. Three means of deter¬
mination.—115. Principles on which the value of fossils depends.—110. Ages in
Geology.—117-119. Unstratilied rocks: examples.—119. General nature of
Veins.—122. Dikes.—123. Simple and banded veins.
V. Historical Geology.—Azoic Time.—Pages 125, 120. Three principles
characterizing subdivisions in all history, whether the limits of an Age arc
marked or not in the rocks.—127. Fourth principle.—Fifth principle.—128. Sixth
principle; use of the word equivalent.—128. True basis of the subdivision into
Geological Ages.—130. The Ages.—The five higher divisions of Time, and their
signification.—Basis of the subdivisions into Periods and Epochs.—134. Cha¬
racteristic and reality of the Azoic Age.—130. Distribution in North America.
—138. Kinds of rocks. 140. Prevalence of iron-ore.—140-142. Arrangement
of the rocks.—113. Their original condition.—Disturbances and foldings.—144.
Proof that there were long ages of quiet in the course of Azoic Time.—145.
Alterations or metamorphism of the rocks; examples.-—The existence or not of
life in the Azoic Age.—147. First expression of the idea of life.—Relations of
the North American Azoic to the present continent.
VI. Animal Kingdom.—Pago 147. Names of the four Sub-kingdoms of ani¬
mals.—Characteristics of Radiates, and examples.—148. Id. of Mollusks.—149.
Id. of Articulates.—151. Id. of Vertebrates.—Recapitulation.—152. Protozoans.
—Names of Classes of Vertebrates.—Characteristics of Mammals, and examples.
—Id. of Birds.—Id. of Reptiles.—Id. of Fishes.—Names of Classes of Articu¬
lates.—Characteristics of Insects, and examples.—Id. of Spiders.—Id. of Myria-
pods.—153. Id. of Crustaceans.—Id. of Worms.—The three Orders of Crusta¬
ceans, and characteristics of Decapods, and examples.—Id. of Tetradccapods.
—Id. of Entomostracans.—154. Id. of Trilobitcs.
VII. Animal Kingdom; Vegetable Kingdom.—Page 155. The three sub¬
divisions of Ordinary Mollusks.—Their characteristics, with examples.—Pecu¬
liarities of the Cephalopods.—156. Peculiarities of the two groups of Ccpha-
lates.—157. Name of the group of Aecphals, and peculiarities.—The three
groups of Anthoid Mollusks.—Peculiarities of Bryozoans.—158. Distinctions
between Brachiopods and Conchifers or the ordinary Bivalves.—The three
Classes of Radiates.—Characteristics of Echinodcrins.—Id. of Acalcphs.—Id.
of Polyps.—159. Distinctions of Crinoids and other Echinodcrms.—1C1. Dis¬
tinctions of the two groups of Crinoids, the Crinidcans and Cystidcans.—162.
Coral-making Acalcphs.—163. The two Orders of Polyps.—Formation of Coral.
—Characteristics of Rhizopods.—165. Id. of Sponges.—165, 160. Two grand
divisions of plants.—Algae or sea-weeds.—Three subdivisions of Phasnogams.—
Characteristics of Gymnosperms, with examples.—Id. of Angiosperms, with
examples.—Id. of Endogens.
VIII. Palaeozoic Time, Silurian Age, Potsdam Period.—Page 167. First
of the Palaeozoic Ages.—Origin of the term Silurian.—167. Names of the three
Periods in the American Lower Silurian, beginning with the earliest.—163. Id.
in the Upper Silurian.—171. The two Epochs of the Potsdam Period.—172.
762
APPENDIX.
General distribution of the rocks in America.—Kinds of rocks.—176. Their
structural peculiarities.—178. Kinds of plants.—179. The Sub-kingdoms of ani¬
mals represented.—The subdivisions of Protozoans represented.—Id. of Ra¬
diates.—Id. of Mollusks, and the peculiarity in this respect of the Molluscan
Sub-kingdom.—181. Id. of Articulates.—182. The most abundant fossils.—186.
Names of modern genera which began in the Potsdam Period.—193. Relation
of Primordial life of Europe to that of America.—195. Igneous ejections, and
copper mines of Keweenaw Point.—196. Evidence as to North American
Geography in the Potsdam Period.—197. Peculiarities in the thickness of the
deposits in the Appalachian region.—199. Formation of the Lake Superior
sandstone and trap rocks.—200. Origin of the material of the fragmental
rocks.—201. Id. of limestones.—202. Evidence as to the climate of the Period.
—Grades of life.—203. Exterminations of life.—Reality of the Primordial
Period in America.
IX. Lower Silurian, Concluded.—Page 205. The second Period in the Si¬
lurian Age.—Its two Epochs.—Characteristics of the Period.—General distribu¬
tion and thickness of the rocks.—207. Resemblance of European to North
American.—Kinds of plants.—208. The prevailing kinds of animal life in the
three Sub-kingdoms represented.—-Two types wholly unfolded.—Absence of Ver¬
tebrates.—Characterislics of Orthocerata.-—Id. of Trilobites.—Id. of Bryozoans.-"
—209. Importance of bivalve Crustaceans or Ostracoids.—217. Third Period of
the Silurian Age.—Its two Epochs.—Kinds and general distribution of rocks.—
219. Kinds of plants.—Animal life.—222. Evidence as to the Geography of
America in the Trenton and Hudson Periods.—223. Subsidence in progress
during the formation of the deposits.—224. Contrast between the Mississippi
basin and the Appalachian region.—Evidence as to climate?—225. Explanation
of the exterminations of species.—226. Recapitulation, as to fresh waters; as to
life; as to the conditions of the continent.—Conditions of formation of the
deposits; oscillations.—227. Instances of unconformability, and what they prove.
—Evidence as to the time of origin of the Champlain valley.—228. Increase
of dry land, and its effectsT^-229. Disturbances in Europe«-\
X. Upper Silurian.—Page 229. General characteristics of the Upper Silu¬
rian.—Periods of the Upper Silurian.—Fourth Period of the Silurian, or first
of the Upper Silurian.—Epochs.—230. First Epoch; general distribution of the
rocks.—Kinds of rock.—Life.—231. Second Epoch; general distribution of the
rocks, contrasting the Interior and Appalachian regions.—Kinds of rocks.—
232. Evidence from structural peculiarities.—Plants.—233. Most common Mol¬
lusks.—-Third Epoch.—Distribution of rocks, comparing the Interior and Appa¬
lachian regions.—Kinds of rocks.—235. Plants.—Common kinds of animal life.
—The Sub-kingdoms represented.—237. Fourth Epoch ; kinds of rocks and dis¬
tribution.—238. Thickness at the Falls of Niagara.—239. General character of
the life.—210, 241. The Sub-kingdoms represented.—243. Geographical changes
in the Niagara Period.—244. Review of the changes after the Trenton Period.—
245. Extent of changes or oscillations of level in the Appalachian and Interior
regions compared.—246. Question as to the existence of land-plants.
XI. Upper Silurian, Concluded.—Page 246. Fifth Period of the Silurian,
or second of the Upper Silurian.—Kinds and distribution of rocks.—248. Im¬
portant minerals.—Mode of occurrence of the gypsum, and its origin.—Mode
APPENDIX.
763
of occurrence of salt.—249. Absence of fossils.—Geography and origin of
the salt in the beds.—251. Absence of land-plants.—Cause of extinction of the
life of the Niagara Period.—Sixth Period of the Silurian, or third of the Upper
Silurian.—General conditions.—Kinds and distribution of rocks, contrasting the
Interior and Appalachian regions.—253. Abundance of life.—Prominent kinds
of animal life.—255. Geography ; contrast with the Salina Period.—256. Gene¬
ral features of the Upper Silurian.—257. Conditions of the continent.—Con¬
trast between the Interior and Appalachian regions.—25S. General features of
the life.—Radiates.—Mollusks.—259. Articulates.—Evidence as to climate.—
260. Distribution of the Upper Silurian.—Formations in foreign countries.—
262, 263. General features of the life.—264. Fishes.—Their appearance in the
Silurian, if true, in harmony with a general law in history.—265. General con¬
clusions.
XII. Devonian Age.—Page 265. Origin of the name Devonian.—Transition
between Silurian and Devonian.—The five Periods in the American Devonian.—
Lower and Upper Devonian ; distinction in rocks.—266. First Period of the
Devonian.—Kinds and distribution of rocks.—Plants.—267. Common Mollusks.
—268. Geographical conclusions.—Region of Appalachian subsidence not cm-
bracing the Green Mountain region.—269. Second Period of the Devonian.—
Three Epochs.—Kinds of rocks, and their distribution.—270. Plants : Proto-
phytcs.—272. Characteristic animal life.—Extent of coral-reefs.—The first of
Vertebrates.—Sub-kingdoms represented.—New genus of Brachiopods.—Animal
remains in hornstonc.—275, 276.—Remains of Fishes.—The two grand divi¬
sions represented, and their characteristics.—The grand division not repre¬
sented.—The kind of Selachians in the early Devonian.—The kinds of Ganoids.
—Characteristic of the tails of the ancient fishes.—278. Geography. >>
XIII. Devonian Age, Concluded.—Page 2S0. Third Period of the Devo¬
nian.—The three Epochs.—281. Distribution of the Hamilton formation.—2S2. The
earliest land-plants; their kinds and relations to modern plants.—284. Gonia-
tites.—286. Geographical conclusions.—287. Life.—Fourth Period of the De¬
vonian.—The two Epochs.—Kinds and distribution of rocks.—289. Life.—290.
Geographical conclusions.—291. Life.—Fifth Period of the Devonian.—Kinds
and distribution of rocks.—293. Geographical conclusions.—294. Foreign De¬
vonian ; what called in Scotland.—295. Plants.—Animals.—299. General Geo¬
graphical features of America.—300. Condition of the region of the Rocky
Mountains and Appalachians.—Condition as to rivers.—Origin of rocks.—301.
Geographical changes.—Geographical condition of Europe.—Two great steps
of progress in the life of the world.—302. Groups to which the land-plants
belong, and the relations of the earliest Flora to these groups.—Reptilian feature
of Ganoids, and conclusion therefrom as to the commencement of the type of
fishes.—303. Changes in the life of the world during the Devonian Age.—304.
Disturbances closing the Age.
XIV. Carboniferous Age.—Page 305. The three Periods; succession of
phases.—Principal areas in North America.—306. First Period.—Contrast be¬
tween the Interior and Appalachian regions in rocks.—310. Prominent features
of the animal life.—Classes of Vertebrates represented.—The first American
Reptiles, and the conditions under which the tracks were formed.—316. Geo.
craphy of North America.—318. Resemblance of American and Foreign Sub.
APPENDIX.
carboniferous.—320. Evidence of disturbances preceding the next Period.—321.
Second Period.—Its Epochs.—Rocks of the first Epoch.—322. Distribution of
the Coal ureas of North America.—324. Kinds of rocks, and proportion between
their thickness and that of the coal beds.—3-5. Evidence that beds arc true Car¬
boniferous.—320. Under-clays; trunks of trees.—328. Kinds of coal.—Vegetable
remains in coal.—329. Pyrites.—333. Kinds of plants, and the groups to which
they belong.—Relation in size to modern Cryptogamous vegetation.—334. Lepi-
dodendra.— 335. Sigillarise.— 337. Calamites.— Conifers.— 338. Ferns.— 343.
General character of animal life.—-Two Classes of Vertebrates represented.—
The three orders of Fishes.—Kinds of early Reptiles.—344, note. The two
orders of Reptiles, and their distinctive characteristics.—352. Extent of Coal
measures in Europe compared with the American.—Id. in Great Britain.—355.
Relations in life to American.—35(5. Insects.
XV. Carboniferous Age, Continued.—Page 359. Evidence that coal is of
vegetable origin.—Plants.—Evidence that the vegetation was land or fresh-water
vegetation, and not. marine.—Coal a result from the decomposition of plants.
—3GI. Presence of water essential.—Evidences as to climate and atmosphere of
the Coal Period.—363. Their influence on the growth of plants.—364. General
Geography of North America through the two Epochs.—366. Evidences as to the
pha ses in the progressing period.—36S. General conclusions.—269. Third
Period of the Carboniferous Age.—Origin of the name.—Distribution of recks
in America, and their kinds.—370. Life.—371. Evidences as to the origin of the
beds.—372. Distribution of the Permian in Europe.—373. Relations of plants
to the Carboniferous.—374. General character of the animal life.—377. Origin
of the Palaeozoic rocks.—Diversities of the three great regions as to rocks.—
385. Id. as to the thickness of the rocks.—Relative duration of the Palaeozoic
ages.—386. Progress in Geographical features of America through the Palajo-
zoic.—387. Mountains.—388. Rivers.
XVI. Carboniferous Age, Concluded.—Page 388. Evidences as to extent of
subsidence in the course of the Palaeozoic.—389-391. Oscillations.—391. Up¬
lifts and dislocations.—392. Direction of oscillations.—393. Relation in direc¬
tion to the forces acting in the Azoic age.—Evidences as to cotcmporaneous
movements in Europe and America.—394. Contrast between Europe and
America.—System of progress in life.—395. First fact stated as to kinds of life,
with examples.—Second fact, with explanation and examples.—396. Third,
fact, with examples.—397. Fourth fact, with examples.—Methods of extermina¬
tions.—C9S. Methods of extinction of tribes, etc.—403. Evidence as to extent
of flexures in the Coal measures of the Appalachians.—404. The whole Palaeo¬
zoic involved in the flexures.—405. Characters of folds on the east, or towards
the ocean.—406. Facts with regard to the Appalachian flexures.—First; second ;
third ; fourth.—107. Fifth; sixth; seventh.—407. Examples of great faults.—
408. Proofs from New England that the crystalline rocks are Palaeozoic.—409.
Alterations of rocks by consolidation.—410. Evidences as to debituminization
of coal.—Extent of crystallization or metamorphism.—Characteristics of the
force engaged: first; second ; third ; fourth.—411. Evidence of identity of force
with that of earlier time.—413. Events marking the transition from the Palaeo¬
zoic to the Mcsozoic.
XVII. Reptilian Age.—Page 414.—Mesozoic Time.—Grand characteristics
APPENDIX.
765
Of the Reptilian Age.—The three Periods.—The first Period.—Distribution of
the rocks in eastern North America, and their kinds.—415. Id. west of the Mis¬
sissippi.—117. Two features of the American Triassic.—418. Plants, as con¬
trasted with the Carboniferous.—120. Deficiencies in marine life.—Articulates.
—421. Classes of Vertebrates represented.—421, vote. Three groups of Mam¬
mals.—Two parallel subdivisions of the Non-marsupials.—122, note. The four
subdivisions of the Megasthenes, with examples of each.—123, note. Id. of
the Microsthenes.—422. Characteristics of the Pishes.-—424. What evidences of
Reptiles occur in the beds.—425. Id. of Birds.—42f>. Id. of Mammals.—450.
Igneous rocks associated with the sandstone on the Atlantic border.—132.
Proofs of heat.—433. Distribution of the European Triassic.—Salt mines.—431.
Prevailing forms of plants.—135. Characteristic animal life.-—Vertebrates.—
438. Conclusion from paucity of marine remains.—-139. Id. from ripple-marks,
etc.—Id. from the thickness of the beds.—Id. from the trap dikes.—110. Gene¬
ral conclusions as to the life of the Period.—Geography.—412. Origin of the
Triassic west of the Mississippi.
XVIII. Reptilian Age, Continued.—Second Period of the Reptilian Age.—
444. Question as to rocks of this period existing or not on the Atlantic border.—
445. Id. west of the Mississippi.—446. Foreign Jurassic.—447. Subdivisions
into three Epochs.—449. Characteristic plants ; no Angiosperms.—150. Charac¬
teristic kinds of animal life.—The last of some Palaeozoic genera of Brachio-
pods.—Ammonites.—451. Belemnites.—Insects.—Characteristics of the Fishes.
—Varieties of Reptile life; Ichthj'osaurs, Plesiosaurs, Iguanodon, Pterodactyls,
etc.—453. Types of Mammals represented.—465. Conclusions with regard to
American Geography.—Different character of European.—466. Characteristic
life.—Question as to an excessive Mammalian or Reptilian population or not,
where the fossils occur.—467. Evidences as to climate (see also page 73S).
XIX. Reptilian Age, Concluded.—Page 467. Third Period of Reptilian
Age.—Origin of name Cretaceous.—Epochs in America.—Distribution of the
beds.—468. Kinds of rocks.—470. Change in the vegetation of America with
the opening of the Period.—472. Important Protozoans.—Characteristic Mol-
lusks.—473. New feature among Fishes.—New types among Reptiles and Mam¬
mals.—479. Rocks of the foreign Cretaceous; chalk; flint.—4S1. Plants.—
Rhizopods.—482. Spicula. of Sponges.—Fishes.—Reptiles.—1SS. Origin of the
chalk.—Id. of the flint.—4S9. Conclusions as to American Geography.—491. Id.
Foreign Geography.—Evidences as to climate.—493. Relative duration of the
Palaeozoic and Mesozoic.—494. Geography of North America.— Decline in Palaeo¬
zoic features during Mesozoic time, as to vegetation.—Id. as to Crinoids and
Brachiopods.—495. Id. as to Fishes.—Progress in Mesozoic features as to vege¬
tation.—496. Id. as to Cephalopods.—497. Id. as to Fishes and Reptiles.—499.
Progress in Ccnozoic features as to plants.—Id. as to Corals and Mollusks.—500.
Id. as to Articulates.—Id. as to Vertebrates.—Examples of comprehensive
types.—501. Position of the earliest Mammals in the Class of Mammals.—Har¬
mony of the Fauna and Flora of an Age.—502. Evidence of disturbances at the
close of Mesozoic time.—503. Revolution slow in progress.—Changes of level
in eastern North America and about the Rocky Mountains.—504. Causes of
the destruction of life.
XX. Cenozoic Time.—Mammalian Age.—Page 505. Contrast in life between
766
APPENDIX.
Cenozoic and Mesozoic time.—The two Periods of the Age of Mammals, and how
distinguished.—506. Lyell's subdivisions of the Tertiary.—Subdivisions of the
American Tertiary.—507. General distribution of the rocks.—Kinds of rocks.—
512. Protophytcs, and general character of other plants.—514. Kinds of Arer-
tebrates.—515. Mammals of the Upper Missouri Miocene.—516. Id. of the
Pliocene Epoch.—523. Importance of Nummulites in the Foreign Tertiary.—
525. Contrast between the Eocene, Miocene, and more modern vegetation of
Europe.—526. First appearance of Snakes, and earliest known of European
Birds.—The earliest Mammals, and where first found.—Characteristic of Eocene
Mammals as stated by Owen.—528. The Dinothere.—530. Evidence as to Ame¬
rican Geography.—531, 532. Elevation of the Rocky Mountains.—532. Progress
of the North American Continent.—533. European Geography.—Elevation of
mountains.—534. Evidence as to climate in America and Europe.
XXI. Mammalian Age, Concluded.—Page 535. Three Epochs of the Post-
tertiary.^—Drift; evidence as to its age.—536. Its distribution.—Its material
and characteristics.—537. Its source.—538. Character and general direction of
scratches.—540. Distribution in foreign countries.—541. Fiords.—The two
theories.—Arguments for and against the Iceberg theory.—543. Id. the Glacial
theory.—545. Example from Switzerland.—546. Geography.—547. Second Epoch.
—Kinds of rocks and distribution; terraces along rivers and lakes.—540.
Ancient sea-beaches.—550. Relation of river-terraces to level of the river they
border.—552. American Geography.—553. Evidence as to the temperature of
the sea and air.—554. Third Epoch.—Distribution of terraces.—555. Their
formation.—557. General results.—558. Some of the animals of Europe and
Asia, and their habits.—561. Id. of North America.—563. Id. of South America.
566.—Id. of Australia.—Characteristics of the life of the Post-tertiary.—567.
Evidences as to climate.—568. Time-ratios of the Palaeozoic, Mesozoic, and
Cenozoic.—Geographical changes during the Tertiary.—569. Id. during the
Post-tertiary.—570. Dynamical agencies intensified beyond their former power
in the Post-tertiary.—571. Prominent fact with regard to the life of the Cenozoic.
XXII. Age op Man.—Pages 573, 574. New feature of the world; character¬
istic of man's structure evincing his intellectual character.—574. Rocks or
deposits.—575. Life that has its culmination in the Age of Man.—576. Occur¬
rence of modern Mammals with some of the Post-tertiary.—577. Change during
the Terrace Epoch.—578. Examples of animals recently become extinct.—580,
583. Fossil relics of Man : their modes of occurrence, and the conclusion they
sustain.—584. Evidence of unity of Man as to species.—Id. of origin on one
continent only.—585. The particular continent of his origin.—586. Creations.—
Two kinds of changes of level.—Examples of secular.—588. Id. of paroxysmal.
590. Evidence as to length of Geological time.—592. Proof of progress in the
life of the globe.—Criteria of rank among animals: first; second; third; fourth;
fifth.—593. Proof that the earliest species of a group were not necessarily the
lowest.—594. Culmination of types at different periods.—595. Comprehensive
types.—Embryonic features of some early types.—596. In the first appearance
of a group, the position as to grade of the earliest species.—598. Extinction of
comprehensive types.—Unity of Floras and Faunas of successive ages.—In what
progress always consisted.—599. Examples of the law of specialization and its
application.—600. Relation of the plan of progress to the Age of Man.—What
APPENDIX.
767
as to life was involved in the progress in climate, etc.—601. Genera ranging
through all time from the first Palaeozoic Epoch.—Cause of extinction of spe¬
cies, and of tribes or higher groups.—601. Teachings of Geology as to the origin¬
ation of species.
XXIII. Dynamical Geology.—Page 603. Subjects treated of under Dynami¬
cal Geology.—604. Life : its protective effects.—605. Its transporting effects.—
Its destructive effects.—606. Conditions determining its importance in rock-
making.— Limiting influence of climate and soil.—Id. of the nature and purity
of the water.—608. Id. of temperature and depth.—Kinds of organic products
from plants; shells; corals; bones; diatoms; sponges.—609. Reasons why
water-species have contributed most to rocks.—611. The grade of species best
fitted for rock-making.—Methods of fossilization.—-612. The method of rock-
making in the case of minute fossils.—Id. in the case of corals and shells.—-613.
Formation of peat.—614. Causes limiting the distribution of coral reefs and
islands.—615. Description of a coral island.—617-619. Formation of the coral
structure.—620. Kinds of coral reefs.—621. Extent and thickness.—622. Origin
of the forms of reefs.—624. Recapitulation.—625. Cohesive Attraction : its
identity with the power of crystallization.—626. Cleavage in minerals and in
rocks.—Cause of the concretionary structure; origin of the columnar forms of
trap.—628. The Atmosphere: its destructive effects through the transportation
of sands.—629. Its method of adding to lands.—Dunes.—Dust-showers.—632.
Effects of changes in atmospheric pressure.
XXIV. Water.—Source of the water of Rivers, and the conditions on which
the amount depends.—634. Law of flow of a stream.—635. Ratio of the force of
running water to the velocity.—General effects of erosion.—Progress of erosion
in forming valleys.—636. Distinction of torrent-portion and river-portion; flood-
plain.—637. Modifications dependent on the nature of the rocks.—641. Pot-holes.
—642. Materials transported by rivers.—643. Extent of denudation over a conti¬
nent.—Wearing of stones.—Amount ,of silt annually carried to the Mexican
Gulf by the Mississippi.—644. Raft of the Red River.—Origin of alluvial
formations, and their features.—645. Origin of deltas.—647. The manner in
which waters become subterranean.—648. The principles on which Artesian wells
are based.—649. Erosion.—The three kinds of land-slides.—650. The Ocean :
means by which the ocean exerts mechanical force.—General system of currents ;
their universality, rate, and position.—652. In what way their positions might
be changed.—Simpler tidal actions.—653. Translation-character of waves on
coasts.—In-flowing currents.—Eagre.—Out-flowing currents.—654. Waves, their
force.—Surface-currents caused by winds.—655. Under-currents id.—Earth¬
quake-waves.
XXV. Water, Concluded.—Erosion by currents.—656. Erosion by waves ; its
extent; height of line of greatest action above low-tide level.—657. Amount
of transportation by oceanic currents, and the materials transported.—658.
Transportation by waves.—659. Formations over the bed of the ocean.—660.
Formations on soundings and along coasts.—Action of tidal and wind currents
in determining the forms of accumulations.—661. Results from the combination
with those of the currents of rivers.—662. The consequent features of the eastern
coast of the United States.—664. Beaches; ripple-marks.—665. Oblique lami¬
nation ; rill-marks.—Erosion during the slow sinking or rising of a continent,
708
APPENDIX.
or when slightly submerged.—06G. Effects if the surface of a continent is nearly
level, there being no mountains.—GG7. Nature of Glaciers.—670. General cha¬
racters and movement.—671. Circumstances influencing their form .tion.—G72.
Law, and rate of flow.—G73. The three principles on which the power of motion
depends.—G74. Cause of the laminated structure of a glacier.—G75. Method of
transportation, and the materials transported.—G7G. Kinds and methods of ero¬
sion.—G77. Origin and effects of Icebergs.—678. Methods by which sedimentary
strata have been formed.—670. Extent of erosion over continents.—GtO. De¬
pendence of topographic effects on the characteristics of the rocks of a country.
XXVI. Heat.—Page 681. Three sources of heat.—GS2. Effects of the sun.—
Id. of chemical and mechanical action.—Effects over the globe of internal heat.
—Proofs of the existence of internal heat.—0S3. Rate of increase with the
depth.—Evidence of internal heat from volcanoes.—6S4. Probable thickness of
the earth's crust.—G85. A volcano; lava; cinders; crater.—Ejections; tufa.—
General geographical distribution of volcanoes, and where few.—GS7. Material
of a volcanic mountain ; lava-cones.—-689. Tufa-cones.—Cinder-cones.—G90.
Mixed cones.—Lava; scoria.—G91. Liquidity of lava; effects of superheated
steam.—Vapors or gases.—692. Effects of vapors.—G93. Movements.—691, C95.
—Causes of eruptions.—G97. Eruptions mostly through fissures, and results.—
G98. Origin of forms of volcanic cones.—700. Geysers.—Source of volcanoes.—
702. Formation of dikes.—701. Metamorphism.—Effects.—703. Changes by loss
of water, or other vaporizable ingredient.—706. Obliteration of fossils, and
crystallization.—707. Origin of metamorphie changes; amount of heat required.
—708. Effects from the water present.—710. Conditions attending metamor¬
phism.—711. Veins.—712. Three methods of filling veins.—The method by
which the larger part of veins have been formed, and evidence of filling by suc¬
cessive supplies of material.—713. Sources of material, and how carried into
open spaces.—714. Alterations of veins.—715. Faulted veins.
XXVII. Movements in the Earth's Crust, and their Consequences.—
Page 71G. The four subjects here included.—Causes of local change of position
or level.—717. Action of vapors; of gravity of deposits; of internal tides.—
718. Effects from change of temperature in the earth's crust, and examples.—
719. Consequences from inequalities in the crust.—Effects how long in progress.
—Direction cf the force, and positions of the axes of resulting plications.—719.
Example in the Appalachians (see pp. 403-407).—721. Flexibility of rocks, and
evidence.—722. Formation of synclinal valleys.—Elevation of mountains.—
Proof that the epochs of elevation occurred only at long intervals.—723. Effects
during the intervening time.—On what the water-level depends.—724. Courses
of elevations may be the same in different periods, different in different periods,
different in the same period.—725. First five causes of fractures mentioned.—
72G. The sixth cause.—The seventh, and its mode of action.'—Direction of frac¬
tures.—727. Causes of faults, and mode of formation.—Mode of production of
slaty cleavage.—728. Id. of joints in rocks.—Characteristics of an earthquake.
The two kinds.—729. Effects.—Earthquake oceanic waves.—730. Cause of
earthquakes.—731. First, second, third, fourth, and Jifth principles mentioned as
to the system in the earth's features.—The sixth.—732. The seventh.—The eir/hth
and ninth.—The tenth.—Deductions as to tho direction, position, and mode of
action of the force originating these features or peculiarities of tho earth.—734.
APPENDIX.
7G9
Deductions from the courses of the reliefs and outlines.—73f>. Application to
North America.—737. Origin of Epochs or transitions in geological history.—
Probable causes of the secular changes in the climate of the globe.—-Accordance
of the earth s progress with the universal law of development.—Effects not due
to physical causes alone.
XXVIII. Cosmogony.
I-—Authorities for the Sections, Views, and figures of Fossils
in this work.
The following are the authorities for the more important illustrations of this
Manual. The works mentioned are those from which the figures or views have
been taken; and although generally the original publications, they are not all
so. When the figures have been made from original drawings not before pub¬
lished (the fact with regard to about 150). the reference is distinguished by an¬
nexing a point of interjection (!). Many of the new figures by Meek under the
Mesozoic and Cenozoic are from a manuscript Palaeontologioal Report of
Lieut. G. K. Warren's Expedition to the Upper Missouri, by Messrs. Meek and
Hayden, the publication of which, unfortunately for science, has been deferred.
The authorities mentioned in the tables that are not the original sources of the
figures cited, are Vogt, Naumann, Phillips, Brown, Pietet, and, in part, d'Orbigny
and Murchison.
1. List of the loorks from which the illustrations have been taken.
Anthony, J. G.: Amcr. Jour. Sci. [2] i.
Author: Report of Wilkes's Exploring Expedition on Geology; id. on Zoo¬
phytes; id. on Crustacea.
Bailey, J. W.: Amer. Jour. Sci. [2] i.
Bayle: Bull. Geol. Soc. de France, 1850-7.
Billings, E. : Rep. Geol. Canada ; Canadian Journal.
Bronn, II. G.: Lethma Geognostica.
Buckland, W.: Bridgcwater Treatise.
Buckley, S. B. : Amcr. Jour. Sci. [2] ii.
Bunbury, C. T. F.: Amer. Jour. Sci. [2] ii.
Conrad, T. A. : Jour. Acad. Nat. Sci. Philad.
Cox, E. T.: Owen's Rep. Geol. Kentucky, vol. iii.
Darwin, C.: on Coral Islands.
Davidson, T.: Publications of the Palmontograpliical Society.
Dawson, J. W.: Acadian Geology; Quart. Journ. Geol. Soc.
D'Orbigny, A. : Paleontologie et Geologic.
Edwards, M., and Ilaimc: Publications of the Palmontographical Society;
Archives du Mus. d'Hist. Nat.
Emmons, E. : Rep. Geol. N. York; Rep. Geol. N. Carolina.
Foster & Whitney : Rep. Geol. Lake Superior District.
Geinitz, II. B.; Verstein. des deutsehen Zcchsteingebirges, etc. 1848.
Gibbes, Pv. W. : Fossil Squalid® of United States, Jour. Acad. Nat. Sci.
Philad., 1849.
Ilall, J.: Rep. Palaeontology of N. Y.; Rep. Geol. Iowa; Regents' Rep. on
State Cabinet of N.York; Canadian Nat. and Geol.
50
770
APPENDIX.
Hitchcock, E.: Rep. Geol. Massachusetts; Fossil Footmarks, 4to, 1S48; Ich-
nology of New England, 4to, 1858; On Surface Geology; Amer. Jour. Sci. xv.
Hitchcock, Jr., E.: Amer. Jour. Sci. [2] xx.
Humboldt: Atlas der Kleineren Schriften, 1853.
Ives, J. C.: Colorado Exploring Expedition.
Johnston, G.: On Zoophytes.
Jones, T. R.: Palaeontology of Canada, Decade III.
Koninck, L. de: Anim. Foss. Carbonif.: Recherches An. Foss.; Mon. Pro-
duetus & Chonetes.
Lea, I. : Fossil Footmarks in the Red Sandstone of Pottsville, fol.
Leidy, J.: Trans. Amer. Phil. Soc. Philad.; Smithsonian Contrib., 1853.
Lesley, J. P.: Manual of Coal, and its Topography.
Lesquereux, L.: Rogers's Rep. Geol. Penna.; Owen's Rep. Geol. Kentucky;
Owen's Rep. Geol. Arkansas.
Logan, W.; Rep. Geol. Canada; Canadian Naturalist and Geologist, Men-
treal; Quart. Jour. Geol. Soc., 1852-57 ; Esquisse Geol. du Canada.
Lyell, C.: Manual of Elementary Geology.
Mantell, G. A.: Medals of Creation; Wonders of Geology.
Marsh, 0. C. : Amer. Jour. Sci. [2] xxxiii.
Meek & Hayden: Amer. Jour. Sci. [2] xxxiii.
Meyer, II. von : Fauna der Vorwelt.
Morton, S. G.: Jour. Acad. Sci. Philad., viii. : Amer. Jour. Sci. [2] xlviii.
Murchison : Siluria, 8vo.
Mather, W. AV. : Rep. Geol. New York.
Naumann, C. F.: Lchrbuch der Geognosie, Leipzig, 1850.
Newberry, J. S.: Annals of Science, Cleveland, 1852.
Norwood & Owen: Amer. Jour. Sci. [2] ii.
Owen, D. D. : Rep. Geol. Wisconsin, etc.
Owen, R.: British Fossils.
Percival, J. G.: Report on the Geology of Connecticut.
Phillips, John: Manual of Geology.
Pictet: Traite du Paleontologie.
Prout, II. A. : Amer. Jour. Sci. [2] xi.
Redfield, J. II.: Amer. Lyceum Nat. Hist. N. York, vol. iv.
Roomer, F. : Kreidebildungen von Texas.
Rogers, H. D.: Rep. Geol. Pennsylvania.
Rogers, II. D. & AV. B.: Trans. Amer. Assoc. Geol. and Nat.
Salter, J. AV.: Quart. Journ. Geol. Soc., 1861; Pal. Canada, Decade I.
Sharpe, D. : Quart. Journ. Geol. Soc., 1847.
Strickland, II. E.: Dodo and its Kindred.
Swallow, G. C.: Rep. Geol. Missouri.
Taylor, R. C.: Statistics of Coal.
Thompson, T. : History of AYrmont, Appendix.
Tyndall, J.: Glaciers of the Alps.
Tuomey & Holmes : Fossils of South Carolina.
Verneuil, E. de: Bull. Geol. Soc. de France.
Yogt, C.: Lehrbuch der Geologie.
Wyman, J.: Amer. Jour. Sci. [2] xxv.
APPENDIX.
771
List of Authorities.
Frontispiece. !—From a painting by Russell Smith.
99
100
101
104
110
118
120
121
122
123
133
20 17 Percival.
95 04, 05 Author.
98 84 Author.
85 Author.
88 Hall.
j 89 Mather.
( 90-93 De la Heche.
98 H. D. <& W. B. Rogers.
109 D. Sharpe.
115 Author.
f 118 Hitchcock.
j 120 Author.
f 121, 122 Author.
{ 124-127 Author.
128-131 Author.
132 Author.
135 ! Meek.
,0. f 136, 137 Owen.
',0 { 138 Logan.
130 139! Author.
( 140 Logan.
140 -j 141 Foster & Whitney.
(142, 143 Emmons.
141 144 C. Whittlesey, in Owen.
142 145, 140 .' Emmons.
, ,o f 148 Author.
{ 154, 156 Ilall.
(157 Vogt.
149 s 158 Buckland.
(159 Hall.
151 171-179 Author.
164 180-192 D'Orbigny.
166 203, 204 Bailey.
205 Logan & Hunt (altered).
207! J. D. Whitney.
208-215 Davidson.
210-227 Davidson.
1S., f 228, 229 Naumann.
18,3 ) 230-230 Davidson.
( 236 A Billings.
| 237-240 Hall.
| 241 ! F. H. Bradley.
j 242, 243 Owen.
(244 Prout.
244 A, 1> Meek & Hayden.
( 245 ! Meek.
{ 245 A, B Logan.
252 A Johnston.
246-252 Hall.
0 ( 253-259 Ilall.
19~ { 260 T. R. Jones.
193 261 Billings.
191 256 A-262 A Murchison.
208 262, 263 Hall.
170
173
181
182
186
187
189
190
191
PAGE FIG.
210
211
264, 265 Billings.
260-271, 274, 275 Hall.
272, 273 Salter.
276 T. R. Jones.
277, 278 Hall.
279-281! Meek.
( 282-285 Billings.
( 286-289! 291-296! Meek.
212-j 290 Salter.
(297-300 Hall.
f 301, 302 Hall.
| 303 Billings.
213 ( 304! 306! Meek.
| 305-307 Salter.
(308-312 Hall.
91, j 313-317 Hall.
214 { 318! Author.
(319 Hall.
320, 322, 324-320 Hall.
215 1 321 ! 323! Meek.
327 T. R. Jones.
329, 331-334 Murchison.
Davidson.
-337, 339 Hall.
! Meek.
J. G. Anthony.
-353 Hall.
! 355! Meek.
Logan.
Ilall.
A Hall.
-303 Hall.
Ilall.
-309 Ilall.
-382 Hall.
-388 Hall.
-391 Hall.
-399, 401-404 Ilall.
! Meek.
-407 Hall.
-412 Ilall.
, 414 Hall.
, 410 Hall.
A ! Meek.
Ilall.
! Meek.
, 430 Hall.
-429 ! Meek.
-434! Meek.
436..M. Edwards and Haime.
Murchison.
Bronn.
Naumann.
Salter.
216
220
221
222
227
231
232
233
235
f 328,
( 330
335
338
349
350-
354
356
357
357
358-
364
936 I
( 370
239 383-
240 389
(392-
241 ( 400
( 405-
242 408-
247 413,
248 415.
249 410
253 {$■
254 {S:
255 431-
( 435,
| 437.
263 -| 438.
| 439
I 110
772
APPENDIX.
207 442-444! Meek.
( 441! Meek.
271 -j 441 A a-d, h, i, k-o ! ...M.(".White.
( 441 A, ! F. II. Bradley.
f 445, 447. 449.Edwards and llaime.
273 ■< 440! 448! Meek.
(450, 451 Billings.
( 452! Meek.
274 j 453-455 ! Meek.
(450! 457 ! Meek.
I 458! Meek.
[ 459 Hall.
270 400,401 Newberry.
977 f 402-404, 408-472 Agassi/,.
{ 405-407 Gibbes.
279 473-481 Agassi/.
281 482 Hall.
2g.^ J 483 Lesquereux.
[ 484! Meek.
284 4S5 Edwards and llaime.
(487, 491-494 Hall.
| 486! 488-490! Meek.
285 1 495. 497 Conrad.
[490 De Yerneuil.
280 498-500! Meek.
288 501 Hall.
( 502, 504 Hall.
[ 503 Vanuxem.
290 505-507 Hall.
291 507 A ! Lesquereux.
( 508 Vanuxem.
292 \ 509, 510 Leidy.
[511 Ilail.
290 j 'r>12 Vogt.
( 513 D'Orbigny.
„q7 f 514, 515 Vogt.
( 510 Pander.
298 517-519 Bronn.
299 520 Mantell.
311 521! 522! Meek.
f 523-520, 528-535 Hall.
6U I 527 ."Swallow.
010 f 530 Norwood A Owen.
313 | 537 Hall.
( 538, 539 Swallow.
Q1 . | 540-543 Hall.
i 544 Ivoninek.
[ 545 ! Meek.
( 540 !...Meek, from a specimen bc-
„ir j longing to A. H. Wortlien.
0 1 547 Agassi/.
[ 548 A ! B ! C ! Newberry.
310 549 Lea.
318 550-552 Ivoninek.
f 553 Koninck.
| 554 Davidson.
319 -j 555 D'Orbigny.
j 550 Koninck.
( 557 ,.... Agassiz.
20
311
348-
349
PAGE PIG.
558 ,T. W. Foster.
i 558 A ! "Wortlien.
559 ! Lesley.
320 500 Dawson.
Bun bury.
Bailey.
334 504-500 Lesquereux.
335 507 Lesquereux.
o.,(> | 508 Bronn.
( 509, 570 Lesquereux.
.,og | 571-574 Newberry.
( 575 Brongniart.
oog ( 570-582 Lesquereux.
1 583 Brongniart.
( 584-586 Lesquereux.
( 587 Brongniart.
( 587 A Lesquereux.
j 588-590 Newberry.
(591 Hall.
| 592-594 ! Meek.
} 595 Cox.
[ 590 ! Meek.
[597, 599-001 Hall.
J 598 .....Ivoninek.
j 001 A, 002 Dawson.
[002 A Lesquereux.
350 003 A ! B ! Newberry.
., r, | 004 A, B Wyman.
| 004 C Marsh.
354 005 Ramsay.
( 006, 008,009 Bronn.
or.7 | 007 Murchison.
i 010 Vogt.
[010 A J. W. Salter.
011-015 ! Meek.
010 A, B, C Geinitz.
617 Murchison.
017 A v. Meyer,
018 Author.
019 Taylor.
(020 II. D. Rogers.
4041 (521 Lesley.
( 022 II. D. & W. B. Rogers.
405 023 H. D. & W. B. Rogers.
400 024 ! Lesley.
418 025 <i, D'Orbigny.
f 020, 027, 029, 030 Emmons.
419 -j 928 E. Hitchcock, jr.
(031 Lyell.
j 032 Emmons.
032 A! L. Sanford.
[ 632 B Author.
,ol_ | 033-037 Hitchcock.
42' ' Redfield.
Hitchcock.
Leidy.
[ 040-048 Emmons.
J 649, 049 A Hitchcock.
[ 050 Emmons.
170
370
378
403
038
(039-044.
42S\ 045
429
431
434
435
43G
437
441
446
449
453
454
455
ngny.
j 702-704 Vogt.
| 705, 706 Phillips.
f 707 D'Orbigny.
,rr \ 708, 712 D'Orbigny.
4Db j 709, 713, 714 Vogt.
[711 Piotet.
,-h, I 715 Vogt (from Buekland).
40' ] 716 . Auckland.
f 717-719 D'Orbigny.
458 1 720, 721 D'Orbigny.
( 722 Mantell.
( 723-725,728 D'Orbigny.
40 J \ 726, 727 Vog-t.
729 Lyoll.
730 D'Orbigny.
731 Lyoll.
732 Mantell.
733, 73,4 D'Orbigny.
735, 737 Bronn.
736 Lyoll.
738 Bronn.
739 D'Orbigny.
740 Piotet.
741, 712 Piotet.
74:',, 741 Mantell.
745 Mantell.
746-749 ! Newberry.
750 Roemer.
751 A! 751 B ! Meek.
752, 757 Roomer.
753 D'Orbigny.
754-756 ! Meek.
758-761 ! 76:',! 764! Meek.
762 Roomer.
476 ^ 705-770 ! Meek.
460
401
462
463
464
471
474
475
477-
478
483
484
485
480
489
512
513
514
516
517
518
519
APPENDIX
F1G' PAGE
051 Percival.
('52 Vogt.
653 Bronn.
f 654 D'Orbigny.
655 Vogt.
656 Lyell.
657 D'Orbigny.
658 D'Orbigny.
659 Vogt.
660 Naumann.
661 Bronn.
662, 663 D'Orbigny.
663 A Bronn.
663 B Penny Cycl.
664! Coast Survey.
665-670 ! Meek.
671, 672 Buekland.
673..D'Orbigny (from Buekland).
694 Vogt.
695, 696 Davidson.
697
698! L. Sanford.
699 Mantell.
700,701 D'Orbi
520
521
522
527
52S
530
538
548
557
559
561
562
564
565
566
579
581
589
015
616
620
622
623
63,0
634
639
640
616
657
661
669
070
773
FIG.
771 ! Meek.
772 Gibbes.
773. Morton.
774 Morton.
777 D'Orbigny.
778-781 D'Orbigny.
782-784 Bayle.
785 Piotet.
785 A D'Orbigny.
786, 788, 789 Vogt.
787, 790 D'Orbigny.
791 Manteil.
792 D'Orbigny.
792 A ! Author.
792 B Ehrenberg.
793-796 ! Lesquereux.
797 E. Hitchcock.
797 A ! L. Sanford.
798-802 ! Meek,
80.3-808 ! Meek.
808 A Buckley.
809-811! 813! Meek.
812, 814, 815 Conrad.
816-818 Leidy.
819-822 !.: Meek.
823-825 Tuomey & Holmes.
826 Pictet.
827 D'Orbigny.
828 ! Author.
829 ! L. Sanford.
830 ! R. Bakewell, jr.
833-835 Hitchcock.
836 R. Owen.
837! 838! Meek.
83,9 11. Owen.
810 Z. Thompson.
841 Vogt.
812 Leidy.
843 D'Orbigny.
844 Strickland.
845, .816 Mantell.
847! From a photograph.
848 Author.
819 Author.
850 Darwin.
851 Author.
852 Author.
853 Author.
854-857 Author.
858-936 Ehrenberg.
93,7 Humphreys A Abbot.
940 ! Mollhausen (Newberry).
941 Ives.
942 ! Coast Survey.
914-9 15 Author.
946 ! A. Hague.
948 ! Guyot (in part).
949-952 Tyndall.
953 Agassiz.
774
APPENDIX.
PAGE FIG.
PAGE FIG.
680 954, 955
681 956-965
Lesley. 703 975,
Lesley. 713 976
Author.
Author.
686 966,
687 967
Humboldt. 716 977..
Author. 720 978..
Author. 748 979 !
Vanuxem.
.Lesley.
Author..
688 968, 969,
689 970-972.
Author. 748 980-982,
....Ehrenberg.
Hall.
,11. D. Rogers.
695 973.,
696 974!
Coan and Judd. 750 984,
Author. 750 983
Physiographic Chart, by the Author, excepting the Topography of the Con¬
tinents by A. Guyot.
As words derived from the Greek, whether Latin (the language of the nomen¬
clature of Natural Science) or English, are often written incorrectly, some of
the more common rules of orthography are here mentioned
1. The Greek * becomes c in Latin and English. Thus, from Kmspcov (Kikeron)
comes Cicero-, from Kserpov (kentron) come centrum in Latin and centre in Eng¬
lish. Other examples are circle, cephalic, microscope, catalogue.
2. The Greek ai becomes sc in Latin and c in English. Thus, from aiOrip
(aither) come sether in the former and ether in the latter; from icuiros (kainos)
and fcooc (zoon) conies eenozoic ; from requalis in Latin comes equal, from ecdift-
cium, edifice. Palaeontology would be correctly spelt Paleontology, although
seldom so done.
3. The Greek oi becomes oe in Latin and or or e in English. Thus, from oimvopia
(oikonomia) come eeconomia and economy.
4. The Greek v becomes y in Latin and English. Thus, from avrofi; (sunopsis)
comes synopsis; from pvrtXo; (mutilos) mytilus; from AiywrtTos (Aiguptos) come
PEgyptus and Egypt.
5. The Greek terminations oj and or become in Latin us and um.
6. In compounding words, the first one takes the genitive form, and if Greek,
o is made its final letter, if Latin, i ; but this vowel is in each case dropped when
the following word begins with a vowel. Thus, from or (gen. orros) and Xoyos
comes Ontology, as in the word Palaeontology; and, in the same word, the first
part, derived from naXaio;, loses the final o; from crux (gen .c rue is) comes cruci¬
form ; from penna, penniform (not penvxform).
7. Specific names named after a locality should end in ensis, as Canadensis
from Canada; after an individual not the discoverer, in anus, as Sayanus from
Say; after the discoverer, they should take the form of the genitive, as Van-
uxemi from Vanuxem.
The initial letter of specific names, in this Manual, has been made a capital
when derived from the name of a place or that of a person, and when a sub¬
stantive.
M.—Scientific Nomenclature.
INDEX.
Note.—An asterisk (*) after the number of a page indicates that there is a reference on ttie
page to a figure of the species or object mentioned; and a section-mark ($) implies that the
page contains a definition, explanation, or characteristic of the word or object mentioned.
Acalephs, 158,§ 162.
range of, in time, 400.
Acanthoteuthis, 451.
antiques, 400.*
Accipenseroids, 280.{1
Acephals, 155, 157.$
range of, in time, 401.
Acid-spring, 248.
Acrodonts, 346.(1
Acrodus minimus, 277.*
nobilis, 277.*
Acrostichites oblongus, 420.
Acrogens, 106.(1
Acrotreta, 184.
Actinia, 148,* 163.$
Actinoid Polyps, 103.$
Actinolite, 60.$
rock, 78.$
Actinocrinus Christyi, 312.*
longirostris, l(il,* 312.*
proboscidialis, 312.*
tenuiradiatus, 209.
unicornis, 312.*
Actinocyclus Ehrenbergii,
512*
Actinoptychus undulatus,
512*
senarius, 166,* 512.*
Adelomys, 520.
Adiromiack iron-mines, 141.
TKchmodus, 455.*
iEglea, 358.
iEpiornis, 580.
yEtiiopliyllum speciosum, 434.
stipulare, 434.
Africa, Cretaceous in, 481.
system in reliefs of, 27.*
Agalmatolite, 61.$
Agassiz on criteria of rank
among animals, 593.
on Ganoid teeth, 280.
on glaciers, 670, 754.
on fishes, 278, 423.
on synthetic types, 393.
Agate, 55.$
Age of Fishes, 205.
of Mammals, 505.
of Man, 573.
of Man, reality of, 5S3.
of Mollusks, 167
of Reptiles, 414.
Ages, names of, 130.
subdivision into, 116.(1
Agnostus AmeHcanus. 103.
Agnostus Canadensis, 193
lobatus, 215.*
Rex, 194*
Agriochoerus, U. Missouri, 519.
Air-breathers in Devonian,
296 299
Aix, fishes of, 529.
Alabama, Carboniferous in,322.
Clinton in, 234.
coal in, 323.
Cretaceous in, 470.
Hudson in, 218.
Millstone grit in, 322.
Subcarboniferous in, 307.
Tertiary in, 508.
Albert coal, 309.
Albian group, 480.
Albite, 56.(1
Alca impennis, 580.
Alcyonium, 103.$
Alcyonoid Polyps, 163.$
Aletliopteris, 338, 355.
Lonchitidis, 340,* 342.
marginata, 342.
Serlii, 339.
Aleutian Islands, 36.
Algc-e, 165, 167,$ 748.
in Hamilton beds, 283.
only plants of Potsdam
Period, 178.
Alleghany epoch, 309.
Allorisma Minnehaha, 371.
subcuneata, 348.*
Alluvial formations, origin of,
644.
Alluvium, 74.$
Alps, elevation of, 533.
Aluminium, 52.$
Alum shale, 74.$
Amber, 09.$
Amauropsis paludinad'ormis,
479.
Amblyrhynchus, 499.
Ambonychia bellistriata, 213.*
radiata, 221.*
Ambulacral pieces, 159.$
America and Europe,difference
in progress of, 394.
America, mean height of, 15.
submerged eastern border
of, 3S5, 441.
system in reliefs of, 24*
the forest continent, 394.
trends of land of, 37.
American character of Miocene
plants of Europe, 525.
Amethyst, 55.$
Amia, 280.$
Amianthus, 61.$
Ammonites, 156, 450, 472, 496.
Altenensis, 465.
bifrons, 464.
biplex, 446, 465.
bisulcatus, 454,* 464.
Bogotensis, 487.
Braikenridgii, 464.
Bucklandi, 464.
bullatus, 464.
Calloviensis, 465.
complexus, 479.
concavus, 446.
Conybeari, 464.
cordatus, 460.
cordiformis, 446.*
coronatus, 465.
decipiens, 465.
Delawarensis, 479.
Didayanus, 487.
Discus, 464.
Dumasianus, 487.
galeatus, 487.
giganteus, 465.
heterophyllus, 464.
Humphreysianus, 460/
464.
Jason, 460,* 465.
Lewesiensis, 482.
lobatus, 479.
margaritatus, 454, 464.
McClintocki, 446.
Nodotianus, 454,* 464.
Parkinsoni, 460, 464.
percarinatus, 478, 487.
Placenta, 477,* 479.
Planorbis, 464.
plicatilis, 465.
prmlonga, 487.
radians, 464.
refractus, 460.
rotundns, 465.
serpentinus, 464.
simplex, 487.
spinatus, 464.
Tethys, 487.
Texanns, 478.
tornatus, 435.*
Yandecki, 487.
vespertinus, 478, 479, 487
775
776
INDEX.
Ammonites YYoolgari, 487.
Wosnessenski, 446.
Ammontidm, first of, 303.
Amu'lia, 165, 74i».
Amphibians, 344.$
culmination of, 497.
Amphibian, earliest American,
310*
Ampbiliole, 69.$
Amphicyon, alii, 529.
Ami>hipoils, 163,,$* 349.
Ampliistegina, 620.
Ampliitherium Broileripii, 453,
462.*
Aniphiuma, 344.$
Ampvx niulus, 216*
Amusium Mnrtoni, 622.*
Amygdaloid, 72,$ 690.$
Amygdaloidal cavities, filling
" of, 716.
Anabacia Orlmlites, 458.
Analcime, 62.$
Anancb.vtes cinctus, 474, 479.
tim iirialus, 479.
Anatifa, 154*
Anchilopus. 629.
Anchithei'iuni, 423, 519, 529.
Ancylocei as, 472.$ 473.
Matlieronianus, 485.*
Andalusite, 58.$
Andrias Sc.heurbzeri, 344.
Angiosperms, 166.$ 333.
first appearance of, 470.
of Tertiary, 513.
Anglo-Parisian basin, 502, 523.
Anhydrite, 61.$
Animal kingdom, 147.?
Animals and plants, distinc¬
tions of, 747.
Animals, criteria of rank
among, 592.
extinction of species of, in
modern times, 578.
of Post-tertiary cotempo-
raneons with man, 676,
577, 578, 581.
systcmless, 597, 748.
Anisopus Deweyanus, 427,*
429 *
gracilis, 427 *
Annularia, 341, 356.
carinata, 374*
sphenophyiloides, 342.
Anogens, 166.$
Anolax gigantea, 517.
Anomalocai'dia Mississippien-
sis, 518*
Anomalocystis, 253.*
Anomia Kuffini, 521.
Anomoepus scambus, 425,428*
Anoplothere, 527.
Anoplotherium an Ungulate.
423,$ 529.
Anorthite, 56.$
Ant-eater, 423,$
Antelope, 423, 529.
Anthophyllite, 60.$
Anthracite,*6s.$ 328, 360.
of the Calriferous rocks
of New York, 754.
Anthracopahemon dubius,358.
Grossarti, 358.
Salter!, 357 *
Anthracosanrns Russelli, 358.
Anticlinal, 105.$
Anticosti rocks, 224, 230, 231,
235.
Clinton in, 235.
Hudson in, 218.
Oneida at, 230.
Medina in, 231.
Anvil Rock, 329.
Apateon, 345.$
pedestris, 358.
Apatite, 65.$
Apennines, elevation of, 533.
Aphanite, 77, 79.$
Aphlehia, 355.
Apiocrinns elegans, 464.
1'arkinsoni, 464.
Royssianus, 458,* 465.
Apiocvstis Uebhardi, 253,*
'255.
Appalachian and Illinois coal
measures, equivalency
of, 329.
coal field, 322.
faults, 198, 407, 720.
flexures, characters of,406.
region, 197, 222, 243, 256,
268, 290, 300, 317, 364,
385, 393, 403.
revolution, 403.
Appalachians, ideal section
of, 405.
not existing in Devonian,
300.
Aporrhais Americana, 477.*
Apteryx, 580.
Aptian group, 480.
Apus dubius, 358.
Aragonite, 63 $
Aralo-Caspian deposits, 523.
Araucaria Cunninghami, 166.*
Araucarian Pines, 166,$* 334.
Araucarites, 337.
Area, 304, 399.
rarbonaria, 34S.*
hians, 522*
licnosa, 522.
Arclncocidaris, 160.
Norwoodi, 313.*
Shumardana, 312.*
YYorthcni, 312*
Arch&'ocvathus Atlanticus,
186*
Minganensis, 186,190,193.
Archmouiscus Hrodiei, 461.*
Arclueopteryx macrurusjol.*
Archaic period, 583.
Archegosaurns, 345.$
Decheni, .">58.
Archimedes, 310.
reversa, 313.*
YVortheni, 313*
limestone, 307.
Arclionts, 422.$
Arctic, Carboniferous in, 324.
Chazy in, 206, 224.
climate of, 224, 280, 362,
467, 567, 738.
Corniferous in, 2S0.
Cretaceous in, 467.
ice of, 668, 677.
Jurassic in, 445.
Jurassic reptiles in, 738.
Arctic, Niagara in, 238, 242.
Post-tertiary of, 549, 567.
Trenton in, 207, 224.
Arctomys, 529.
Arenico'la l'iscatornm, 155.*
Arges armatus, 297.*
Argillite, 75, 77.$
Argonauta, 156.$'
Arionellus cylindricus, 193.
Oweni, 189.
Arisaig rocks, 235.
Arkansas, Azoic in, 137.
Carboniferous in, 323.
Cretaceous in, 469.
lower rocks above the
Potsdam wanting, 245.
Subcarboniferous in, 306.
Tertiary in, 510.
Millstone grit in, 322.
Arkose, 83.$
Armadillo, 423.$
group, Post-tertiary, 566.
Artesian wells, 648,* 682.
Arthrophyous Harlani, 232.*
Articulates, 149,152.$
Artie •dactyls, 422.$
Arvieola, 529.
Asaphus gigas, 210,* 215,* 216,
222.
illmnoides, 193.
megistos, 220, 222.
olitusus, 210.
Powisii, 216.*
Asbestos, 60.$
Ascidians, 157.$
Asiiburton group, 294.
Asia, Cretaceous in, 481.
Jurassic in, 447.
system in reliefs of, 25.*
trends of laud of, 38.
Triassie in, 443.
volcanoes of central, 687.
Asplialtic coal, 6S.$
Asphaltum, composition of,
360.
Aspidorliynchus, 461*
Aspidura loricata, 435.
Asplenites, 338.$
Astarte Conradi, 517.*
elegans, 465.
Laurent iana, 552.
minima, 459,* 465.
ovata, 465.
Asterias, 160.
Asteroids, 159,$ 160.
Asterophylliles, 341,$ 356.
ovatus, 341.*
parvula, 200.
sublevis, 341.*
Astrica, 163, 618.
Astroceenia Sancti-Sabm, 474
Astylospongia parvula, 211.
Atacania desert, 47.
Atliyris, 182.*
concentrica, 181.*
congesta, 237.*
lamellosa, 318.*
spiriferoides, 284*
subtilita, 348,* 357, 362,
371.
Atlantic border of continent
under water, 385.
border region, 413.
INDEX.
777
4-tIantio currents, 41, 051, 657.
currents in Potsdam Pe¬
riod, 200.
ocean, 11.
trends of islands of, 38.
Atmosphere, agency of, 6:28.
currents of, 44.
of the Carboniferous, 362.
Atrvpa, 182,* 303.
'aspera, 2X4,* 302.
aprinis, 201.
ooncentrioa, 2X4.*
fallax, 302.
lieniisplierica, 237.
Hystrix, 290*
impressa, 274.
lamellata, 243.
noilostriata, 240.*
reticularis, 237,* 242, 255,
201, 202, 270, 274, 284.*
Augite, 00.(1
rock, 78.(1
Auk, extinction of, 5X0.
Aulopora cornuta, 273.*
Aulosteges, 1X4.
Auriferous quartz, age of,413.
Aurochs, 5x0.
Auroral series, 379.
Austin limestone, 470.
Australia, Jurassic in, 447.
Permian in, 444.
Post-tertiary life of, 560.
system of reliefs of, 29.
the continent of Marsu¬
pials. 500, 5X5.
Triassic in, 443.
Australian character of early
Tertiary vegetation in
Europe, 525.
Australasian chain of islands,
34.*
Austria, Tertiary of, 523.
Authorities of figures, 769.
Avellana Cassis, 484.*
Avicula, 399.
demissa, 221.*
cmacerata, 241,* 242.
I'lahella, 2X4.*
Kazanensis, 375.
rliomlioidea, 237.*
rugosa, 255.
socialis, 435,* 43S.
Trentonensis, 213.*
Aviculopecten aviculatus,
349.
duplicatus, 290,*
rectilateraria, 348.
Aximea Siouxensis, 478
Tumulus, 521.
Axinus, 375, 376.
dul tins, 375.
oliscurus, 375.
last of, 376.
Axolotl, 344.JJ
Aymesiry limestone, 200.
V/.oic, 172.ji
Age, 134.
Age, life of, 145.
beds, original condition
of, 143.
beds displaced, 144.
forces continued through
the Palieozoic, 393.
Azoic, geographical distribu¬
tion of, 135.
nucleus of N.America, out¬
line of, repeated in out¬
line of the continent,736.
N. American, relations of,
to the continent, 147.
rocks of, 139.
rocks, altered, 711.
rocks, strike of, 144.
Azores, 38.*
Babbago, on distribution of
detritus, 059.
Bache, A. 1)., formation of
Sandy Hook, 604.
on the oceanic waves of
the Sinioda earthquake,
730.
Bacillaria paradoxa, 100.*
Baculites, 473.-}
anceps, 485, 4S7.
compressus, 477,* 479.
ovatus, 473, 477,* 479.
Badger, 422.§
Bagshot beds, 522.
Bailey, on Atlantic-bottom
Rlii/.opods, 064.
on Kaintcliatka sound¬
ings, 4X8.
on origin of Green-Sand,
749.
on Polycystines, 612.
on structure of coal, 328.
Bajocian group, 449.
Bakewellia antiqua, 371, 375.
parva, 370.*
Bala formation, 207.
Balama, 529.
palteatlantica, 521.
prisca, 521.
Bahvnodon, 529.
Ballston Spa, 219.
Bandicot, 424.(1
Banks Land, Carboniferous
in, 324.
Baphetes planiceps, 350.
Barbatia Mississippiensis,518.*
Barnacles, 154.jl
Barrande, on Bohemian fos¬
sils, 262.
Barriers, sand, of coasts, 662.
Basanite, 55.
Barton clay, 522.
Barvtes, 05 ji
Basalt, 89.jl
Basaltic columns, 118, 702.
origin of, 627.
Basset edges, 105.(1
Bats, 347.(1
(Cliii'opters), range of, in
time, 572.
Eocene, 527.
Bathonian group, 449.
Bath oolite, 448.
Batliurst Island, Carbonife¬
rous in, 324.
Batliyurus capax, 193.
parvulus, 189.
Salfordi, 193.
seueetus, 189.
Bathvgnatlius borealis, 424.
' 428*
Batrachians, 344.§
Bavaria, Carboniferous in, 321.
Bay of Pundy, 653.
Beach formations, 664.
structure of, 93.(1
See Sea-beaches.
Bear, 422.
Cavern, 559.*
Bear-Opossum, 424.g
Beatricea, 257.
Beaumont, Elic do, on systems
of mountain-elovation,
229, 412, 502, 533, 721.
Beavers, Post-tertiary, 562.
Beek, oil the Salilerous, 247.
on sea-water, 650.
Beetles, 420.(1
Beinertia, 355.
Belemnitella mucronata,477,*
479, 485, 487.
Belemnite, osselet of, 454.*
Belenmites, 156, 451,\ 496.
acutus, 464.
clavatus, 464.
densus, 446.*
giganteus, 464.
lnustatus, 460, 465.
irregularis, 464.
paxillosus, 446, 454,* 464.
pistilliformis, 404.*
Belgium,Carboniferous in, 352.
disturbances in, 412.
Subcarboniferous in, 318.
Tertiary in, 523.
Belleroplum bilohatus, 213,*
216, 221, 237.
carbonarius, 349.'*
patulus, 285.
rotundatuni, 210.*
Urii, 349, 302.
Bellinurus rotundatus, 358.*
Belodon, 437.
Belonostoinus, 427.
Beloteuthis, 454.
Beluga Leucas, 403.
Yermontana, 552, 503.*
Bembridge beds, 522.
Benton group, 409.
Bernardston, Mass., Upper
Ilelderberg at, 270.
Beryl, 59.j)
Beryx Lewesiensis, 485.
superbus, 480.
Beyriehia Americunii, 349.
symmetrica, 242.*
Biche-do-mar, 159.(1
Bilin, intusorial beds of, 524.
Binstead beds, 522.
Biotite, 57.(1
Birds, 152.(1
earliest in Europe, 453,
751.*
in Triassic, 425.
number of living, 575.
range of. in time, 572.
Birdseye limestone, 85.jl 206.
Biselipf on decomposition of
wood, 300.
Bison latifrons, 503.
Bituminous coal. 08, 328, 300.
shale, 73.(1 ill 8.
Bivalves, 157 <i
Black Hills, Azoic at, 137.
778
INDEX.
Black Hills, lower rocks want¬
ing. 245.
Potsdam at, 174.
River limestone, 200.
slate. 282.
Black-lead, 04.$
Blastoidorrinus carcliaridens,
200.
Blastoids, 102.$
first of. in Europe. 290.
range of, in time, 400.
Blattina prinneva, 358.*
venusta, 350.*
Blende, 04.$
Blood-rains, 031.
Blue limestone, 217.
Bognor beds, 522.
Bog ore, 574.
Bohemia, Azoic in, 137.
disturbances in, 412.
number of species in Si¬
lurian of, 2ti2.
Primordial in, 178.
Upper Silurian in, 200.
Bolderian group, 523.
Bone bed in Pennsylvania
Triassic, 424.
Bones, analyses of, 07.
Borucite, 80.$
Bore, 053.$
Bornia. 350.
Bos, 529.
Americanus, 5S0.
Bison, 580.
primigenius, 5S0.
Urns, 580.
Botlirodondron, 350.
Boulders, large, 537.
See Drift.
Bovine family, range of, in
time, 572.
Bracliiopods, 158.$*
culmination of, 397.
families of, range of, in
time, 400.
number and character of
Tertiary, 520.
range of, in time, 400,494.
structure and subdivi¬
sions of, 179.*
Brachyurans, 153.$*
first species of, 375.
Bracklesham beds, 522.
Bradipus tribe, 423.*
Braintree, Trilobites at, 184.
Brandon Lignite and fruits,
510, 514*
Breccia, 73.3
Breckenridgc coal, 3.30.
British America, Cretaceous
in, 407.
Brongniarf, on Tertiary vege¬
tation, 525.
Bronn. on number of Mesozoic
Conehifers, 500.
Brontozoum giganteum, 429.*
Brown coal, GS.$
Brutes, 42.3.$
Bruxellian group, 523.
Bryozoans, 157.$
Bucania rotuntiata, 210.*
range of, in time, 401.
Bucania trilobate, 233, 237.
Buffalo, American, 5S0.
Buhrstone, 83.$
in Ohio, 320.
in S. Carolina, 509.
Bulla speciosa, 477.*
Bumastis Barriensis, 201.
Hunter Sandstein, 433.
Buprestis, 401.*
Burlington limestone, 307.
Busycon iucile, 522.
first of. 484.
Buthotrepliis antiqua, 179.
gracilis, 208.*
succulosus, 208.*
Butterfly, 420.$
Cadent series, 379.
Calamaries, 150,$ 451.
Calamites, 283,333,$ 337,§ 35G,
395, 420.
arenaceus, 43S.
camueformis, 337.*
C'istii, 337.
Mongeoti, 438.
nodosus, 337.
Pacliyderma, 337.
Puckowi, 342.
Traiisiticmis, 290.
range of, in time, 494.
Calamopsis Danai, 514.*
Calcaire coquillier, 433.
grossier, 523.
lacustre, 523.
pisolitique, 4S0.
siliceux. 523.
Calcareous rocks, 70.$
Calceola, 184,* 303.
sandalina, 183,* 274, 296.
schist, 290.
Calcite, 6l'.$
Calcium, 53.$
Calciferous sandroclc, 175.
California, Cretaceous in, 409.
Tertiary in. 5U7, 60S), 510,
511, 521. '
('aligns, 154.
Callianassa Oregonensis, 521.
Callipteris, 338, 355.
Callista imitabilis, 517.
t-ayana, 521.*
sobrina, 517.
Callocystites Jewettii. 148,*
240.
Callovian group, 419.
Calymene Blumenbacliii,
154* 21G, 242, 2ol.
Blumenbachii var. X'iaga-
rensis, 241.
crassimarginatus, 275.
sonaria, 210,* 224.
Calyptropliorus velatus, 517.
Camaroplioria, 375, 37G.
Crumenn, 370.
Schlotheimi. 375, 376.
superstes, 375.
last of, 376.
Cambrian rocks, 177.
Camelus, 423,$ 529.
Camelopardalis, 529.
Camelops, 11. Missouri, 519.
Camorella antiquata, 187.
calcifera, 191.
Campanularia, 142.
Campinian1 group, 523.
Campylodiscus Clypeus, 031.*
Canada, Azoic in, 137.142.
Calciferous in, 175.
Cliazy in. 205.
Clinton in, 235.
Crustacean tracks in Pots¬
dam of, 185.
Hamilton in, 282.
Hudson in, 218.
iron-mines, 141.
Lower Ilelderberg in, 251.
mineral oil in, 754.
Niagara in, 238.
Oriskany in, 206.
Post-tertiary in, 549.
Potsdam in, 174.
Salina in, 247.
Trenton in, 200.
uplifts in, 304.
Upper Ilelderberg in, 270.
Utica shale in, 217.
Cancer, 150.*$
Canis, Miocene. 529.
in Missouri Pliocene, 522.
Cannot coal, 6N,$ 328.$
coal, formation of, 3( 8.
Canon of the Colorado, 509,
03S.
Capelin, Post-tertiary. 552.
Caprina limestone, 470.
Caprotina Texana, 475.
limestone, 470.
Oapybara, 423.$
Carbon, 54.$
Carboniferous Age, 305,751.
conformable with lower
rocks, 305.
divided by the Cincinnati
uplift, 330.
in New England, 409.
life exterminated, 403.
overlying Potsdam, 245.
Potsdam fossils in. 325..
thickness of, 386.
unconformable to Devo¬
nian, 304.
Carcliarias. 8ceCAEciiAR0D0N.
Carcharodon, 477.
angustidens, 277.* 519.
niegalodon, 514, 519, 521.
Oarcharopsis IVortlieni, 315.*
Cardinia concinna, 4(i4.
Cardiocarpum, 338, 350.
bicuspidatum, 338.*
elongatum, 338.*
sanmracforme, 338.*
Cardita Blandingii, 517.
densata, 517.
planicosta, 517.*
rotunda, 517.
Cardium diversum, 518.
dissimile, 4C5.
Groenlandicum, 552.
Islandicum, 552.
multistriatum, 478.
Nicolleti, 517.
Virginianum, 521.
Caradoc sandstone, 207.
Carnivores, 422.$
marsupial, 424.$
range of, in time, 572.
Caroline Archipelago, 35.
INDEX.
779
Carpathians, elevation of, 533.
Carpolitlies, 356.
Brandonensis, 514.*
irregularis, 514.*
Caryoorinus ornatus, 240,*
242.
Curyophyllia, 163.2
Caseyville conglomerate, 322.
Cassidulus, 160.2
Castor, 529.§
in the Upper Missouri
Pliocene, 522.
Canadensis, 56.3.
Castoroides Ohioensis, 503.
Catarrliines, 422.2
Catopterus gracilis, 427.*
Catskill beds, 291, 293.
Mts., glacial scratches on,
753.
period, 291.
identity of, with Clie-
numg, 750.
slialy limestone, 252.
Cat-tail family in Triassic, 434.
Cauda-galli grit, 269.
Caulopteris, 355.
punctata, 33S.*
Caverns, containing human
relics with bones of ex¬
tinct mammals, 582.
Post-tertiary, animals of,
559.
Cenomanian group, 480.
Cenozoic time, 505.
characteristics of life of,
571.
time-ratios of, 568.
Centronella, 181.J
Centemodon sulcatus, 428.
Cephalaspids, 280.jJ
Cephalaspis, 264, 2S0.
Lyellii, 298.*
Ceplialates, 155, 156.2
range of, in time, 401.
Ceplialopods, 155-2
a comprehensive type,
397, 753.
culmination of, 397, 496.
range of, in time, 401.
Ceratiocaris, 255.§
Ceratites Americanos, 478.
nodosus, 435,* 438.
Ceraurus (Cheirurus) insignis,
242, 261.
Cervus, 522, 529-2
Americanus, 563.
Cestracion Pliilippi, 278.*
Cestracionts, 278.|
of the Subcarboniferous,
315.
range of, in time, 402, 572.
Cetaceans, 423.2
first of, 47S.
range of, in time, 572.
Cetiosaurus, 346,2 462.
Chabazite, 62.g
Chaeropus, 424.2
Chsetetes, 162_2
Lycoperdon, 211,* 224.
Chalcedony, 55.§
Chain-coral. See IIalysites.
Chalicomys, U. Missouri, 521.2
Chalk, So.g
Chalk, Gray, 480.
in the Pacific, 488, 755.
none in America, 468.
origin of, 488.
White, 480.
Chalk-Marl, 480.
Cliama, 472.
corticosa, 521.
Champlain epoch in America,
547.
in Europe, 558.
Chart, physiographic, 11, 42,
587,'731.
Chazv epoch, 205.
Cheirolepis Traillii, 279.*
Cheirurus Apollo, 193.
Chelone planiceps, 462.
Clielonians, 345,2 347.
range of, in time, 572.
Chemung beds, section of, 288.
group, 288.
Period, 287.
Chert, 83.g
Clierty limestone, 382.
Cherzolite, 78.2
Chester limestone, 882.
Cliilliowee sandstone, 175.
Chili, recent changes of level
in, 588.
Chinnera, 278.?
Chimau'oids, 27S.§
Chimpanzee, 422.
China. Carboniferous in, 352.
Cliiropters, 428.2
range of, in time, 572.
Chirotherium, footprints of,
436.*
Cliiton, 399.
Chlamydopliorus, 423.2
Clilaniydotlierium, 423.J
Chlorite, 61.2
Cliloritio Schist, 81.§
Clioeropotamus, 526, 529-2
in U. Missouri, 521.
Cliondrodite, 00.2
Clionetes, 184.*
rornuta, 237.*
Dalmaniana, 319.
Plemingii, 371.
hemispherica, 274.
lata, 183*
mesoloba, 348.*
ornata, 313.*
setigera, 284.*
variolata, 314.*
Chonophyllum magnificum,
273.
Niagarense, 240.*
Chouteau limestone, 308.
Chrysalidina gradata, 164,*
483*
Chrysolite, 60.2
Chrysotile, 61.2
Cicadas, 420.2
Cidaris, 160.2
Blumenbaeliii, 4 8.*
coronata, 465.
lieinigranosus, 478.
Cincinnati uplift, 393.
C'inder-cones, 689.*
Cinders, 685-2
Cimnunomum Mississippi-
ense, 514.*
Oirripeds, 154.2
Cithara Mississippiensis, 518.*
Cladodus liiarginatus, 319.
spinosus, 315.*
Claiborne epoch, 506, 50S, 516.
Clathropteris, 445.
rectiusculus, 420*
Clay, 65.2
ironstone, 329.2
slate, 77-2
Clayey layers, plication of,
710*
Cleavage, 55,2 626.
in rocks, 100,2 626, 727.
production of, in glaciers,
674.
Oleodora, 150.*
Clepsvsaurus Pennsylvanicus,
' 428*
Cliff limestone, 288.
01 ill's, wearing of, 656.
Climactichnites Wilsoni, 189.
Climate, causes determining,
45.
causes of the serial
changes in, through
the geological ages, 787.
change of, at close of Cre¬
taceous, 538.
of the Carboniferous, 361.
of the Cliampiain epoch,
553.
of the Corniferous period,
280.
of the Cretaceous, 491.
of the Jurassic, 467.
of the Post-tertiary, 567.
of the l'otsdam Period.
202.
of the Tertiary in North
America, 534.
of the Tertiary in Europe,
534.
of Trenton period, 224.
of Upper Silurian, 259.
Clinch Mountain sandstone,
384.
Olinoclilore, 61.2
Clinometer, 106-2
use of, for measuring the
slopes of distant moun¬
tains, 18.
Clinton epoch, 2.83.
Clymenia Sedgwickii, 297.*
Clypeaster, 160.2
Rogersi, 519.*
Eocene, 517.
Clypeus llugi, 149,* 464.
Patella, 464.
Coal, mineral, 68.2
mineral, impurities of,
360.
mineral, structure of. 327.
a result of decomposition
of plants, 359.
beds, amount of vegeta¬
tion for, 367.
beds, thickness of, 327.
debituniinized, 410.
in Subcarboniferous, 307.
in Triassic, 417.
workable areas of, 322
352.
780
INDEX.
Coal-making decomposition
only under water. 361.
Coal-measures, 322, 352.
dirt-Rods of, 326.
division of, 329.
false, 309.
set ,tion of, near Nesque-
honing, Pit., 403.
section of, tit Trevorton
Gap, I'll., 404.
origin of, .'!.ri9.
vegetation, character of,
333.
Coal-period, summary of, 368.
Coiil-plants, 359.
distritiution of genera of,
dan.
number of, 342.
growth of, odd.
Coitn, T., on eruptions on Ha¬
waii, 097, 099.
Coast-harriers, 200, 002.
Coast-formations, 000.
Coast-outline of Atlantic, 441.
Cooconeis atmospherical, 031.*
lineata, 031.*
Coeconema cymbiforme, 631.*
Cocrosteus, 279,? 298.
Coccoteuthis, 4(*)0.g
Cocliliodus, 278.(1
contortus, 315,* 319.
nobilis, 314.*
Coeciiians, 344.(1
Oeehieanthus elegans, 350.
Cohesive iittraction, 025.
Coins, fossil, 580, 581.*
Ooleopters, 420.?
Colorado, Cafioiis of, 509, 038.
Upper, Cretaceous in, 409.
Upper, Jurassic in, 445.
Upper, Triassic in, 417.
Colors, original, on fossil
shells, 204, 319.
Colossochelys Atlas, 526.
Coluinnaria, 212.-1
iilveolafti, 299,* 211.
Columnar surfaces in Niagara
group, 239.
in Onondaga salt group.
247.
Comanche Peak group, 470.
Comatula, 101.(1 458.
Comprehensive types, 203. 595.
types becoming extinct,
397.
types, examples of, 395,
* 397, 590, 754.
Compsemys, Eocene, 517.?
Conchifers, 157.?
tirst of, 191.
range of, in time, 401.
siphonated, 397.
Concretionary structure, 90.?
Concretions, origin of, 020.
Cones, fossil, 335.
Conferva>, 833.2
Conglomerates, 70, 73,? 377.
Conifer, earliest in Britain.
295.
Conifers, 418.?
of Tertiarv, 514.
pith of. 337.
structure of, 100.?
('oniston group, 200.
Connecticut. ('arlioniferous in,
409.
Devonian in, 499.
trap dikes of, 20,* 430.
Triassic in, 410.
lliver valley, submarine
continuation of, 5)44.
valley, terraces in, 55)7.
valley trap dikes, origin
of, *703.
Oonocardium, 397.
Jihinienbachii, 191.
dipteruni, 210.*
imniaturum, 213.
trigonah;, 275.
Oonocephtilus minutus, 188.*
Conrad, on Tertitiry shells,
517. 521.
Consolidation of strata, 409.
causes of, 704.
Continent, definition of, 2!).?
erosion over, when near
the ocean's level, 605.
of progress, the Orient
the, 585.
Continents and oceans, early
outlined, 732.
arrangement of, 11, ID.
distinctive animal types
of, 585.
moan heights of, 15.
submerged borders of, 12.
system in reliefs of, 23.
Contraction, change of level
from, 718.
effects of, in a cooling
splieie, 718.
Conularia, 215,? 496-2
gracilis, 215 *
last of, 455.
Conns adversarius, 522.
tortilis, 517.
Cook, <}. II., on New Jersey
Cretaceous, 469.
on elevation of U. S. coast,
587.
Copper, boulders of, 536.
of Lake Superior, 195.
Copper-glance, 64.?
ore in the Oneida, 230.
Coprolites, 66.?
analyses of, 67.
in Triassic, 428, 438.
Saurian. 457.*
Corallian group, 449.
Corallines, 67, 147.?
Coralline Crag, 523.
limestone, 238, 242.
limestone, fossils of, 242.
Corallium nubile, 67.
Corals, range of, in time, 400.
rate of growth of, 752.
Coral islands, chalk on,488,755.
islands, evidence from, of
change of level in the
Pacific, 587.
islands, gypsum on, 443.
limestone, 85,? 617.
rag, 448.?
reef, ancient, 239, 270, 272.
reefs and islands, forma¬
tion of, 614.
Coral reefs of Florida, 754.
reefs, rate of increase of,
591, 754.
reef seas, isothermal line
limiting, 42.
rocks, 85, 617.
rock, oolitic, at Key lVest,
201, 754.
Corbicula intermedia, 517.*
Corhula bicarinata, 517.
gibbosa, 517.
mactriformis, 517.*
Cordaites, 356.
angustifolia, 283.
borassifolia, 342.
Kobbii, 290.
Cornbrash, 448 ?
Corniferous limestone, 269.
Corsica range, elevation of, 533.
Coryphodon, 529.?
Cosciuodiscus, 630.*
apiculatus, 512.*
atmospherical, 630.*
gigas, 512*
Cosmogony, 741.
Cotopaxi, 686.*
Crania, 184,?* 399.
divaricate, 216.*
Crassatella alta, 517.*
Mississippiensis, 518.
Craters, 685.?*
See, further, Volcanoes.
Creations since that of Man
unknown, 586.
Orematopteris, 305.
Crepidula costata, 521*
Cretaceous beds, equivalency
of American and Euro¬
pean, 480.
formation, thickness of,
504.
N. American, map of, 489.
period, 467.?
species, distribution of.
487.
Cricodus, 279*
Crinideans, 161.?
number in L. Silurian, 212.
range of, in time, 400.
Crinoidal epoch, 310.
Crinoids, 159, 161.?
range of, in time, 494.
Crioceras, 472.?
ltuvalii, 485.*
Cristeilaria rotulata, 474.
Crocodiles, first of, 464.
first European, 483.
Tertiary, 526.
Crocodilians, 346.?
Crocodilus, 464, 498.
hasifissus, 47S. '
basitruncatus, 478.
clavirostris, 478.*
macrorhynchus, 519.
range of, in time, 572.
Crotalocrinus rugosus, 203.*
Crustaceans, 153.?
range of, in time, 401.
rank of earliest, 395.
Crustacean tracks of Triassic,
427.*
tracks of Potsdam, 185.
Cryptocerue, 214.
INDEX.
781
Cryptoeeras undatum, 214*
Cryptogams, 165.?
existing, 333.
Crystalline rocks, formation
of, 700.
Crystallization, 625.$
a result of metamorphism,
701).
Crystallizations, alongside of
dikes, 70S.
Ctenaeantlius major, .319.*
Ctenodonta nasuta, 213.*
Ctenoides gigantea, 453,* 464.
Otenoids, 278.?
Culmination of types, 400, 571,
594.
Ctineolina Pavonia, 164,* 483.*
Currents, atmospheric, 44.
oceanic, 39,* 650, 652, 654,
657.
oceanic, erosion by, 655.
Atlantic, in the Potsdam
period, 200.
Cutch, recent changes of level
in, 588.
Cuttle-fish, 155.?
Cyathaxonia prolifera, 347.
Cyatliea eompta, 338.*
Cyathocrinus, 162.?
ornatissimus, 2S9.
Cyathophylliils, 163.?
Cyatliophylloid corals, a com¬
prehensive type, 756.
corals, last of, 374.
Cyatliophyllum, 163.
rugosum, 273.*
Cycads^ 418,? 500.
a comprehensive type, 597.
distribution of, 418.
in Maryland beds, 472.
range of, in time, 495.
Cycloids, 278.?
Cyclonema cancellata, 237.*
sulcata, 249.
Cyclophthalmus Bucklandi,
358.*
Cyclopteris, 338,? 355.
elegans, 339.
Jacksoui, 283, 290.
Linnieifolia, 420.*
pachyracllis, 420.
range of, in time, 494.
Cylindrites acntus, 464.
Cymbella maculata, 631.*
Cynotion, 529.?
Cyperites, 336.?
Cyprjea, first of, 484.
Carolinensis, 522*
fenestralis, 517.
lintea, 517.
Peiliculus, 522.
spheroides, 517.
C.vpricardia angusta, 293.
Cypridina serrato-striata, 297.*
Cypridina slates, 295.
Cyprina arenaria, 478.
Cypris, 154.?
in Triassic, 426.
Cyrtia, lS2.g
umhonata, 284.
Cyrtoceras annulatum, 214.*
dorsatum, 371.
undulatum, 275.
Cyrtolites compressus, 213*
ornatus, 221.
Trentonensis, 213.*
Cystideans, or Cystitis, 161,?
395, 398.
a comprehensive tvpe, 597.
last of, 303.
number of, in L. Silurian,
212.
range of, in time. 400.
relation of, to Mollusks,
597.
Cystiphvllum Siluriense, 203.*
Cytlxere Americana, 151.*
Dadoxylon, 283.?
Brandlingi, 337.
Ouangondianum, 290.
Dakota. See Missouri, Upper.
Dakota group, 409.
Dalmania calliteles, 286*
Ilausinanni, 188,* 255.
limulurus, 241,* 242.
nasuta, 262.
pleuroptyx, 253, 254, 255.
selenurus, 275.
Danian group, 480.
Daphnia, 154.?
Dartmouth group, 294.
Darwin, C., on Atlantic dust-
shower, 631.
on coral islands, 622.
Dasypus group, 423.?
group, Post-tertiary, 556.
Dasyurus, 424.?
Dauhree, on formation of sili¬
cates by means of super¬
heated steam, 708.
Davidsonia, 185.?
Dtivis,effects of tidal action,661.
Dawson, J.W., on fossil wood,
266, 283.
on land-snails, 347.
on Xylol litis, 350.
Deane, on tracks of Insects,427.
Debituminization, 410, 705.
Decapods, 153.ji
range of, in time, 402.
Decomposition of wood, 359.
Deer, Eocene, 572.
De Laski, on the Penobscot
glacier, 545.
Delaware, Cretaceous in, 409.
Delpliinus, 529.
Conradi, 521.
Delta formations, 644, 663.
of the Indus, recent
changes of level in, 588.
Delthyris shaly limestone, 252.
Delthyris. See Spiriper.
Dendrerpeton Acadianum, 350.
Dendrophyllia, 148.*
Dentalina pulchra, 474.
Dentalium, 399.
Mississippiense, 517, 518.*
obsoletum, 349.*
Depth of growing corals, 619.
of species, zones in, 60S.
See Ocean.
Dertonian group, 523.
Deserts, distribution of, 45.
Desmidiem, in hornstone or
flint, 271.* 311. 481.
Detritus, 74.?
along sea-shores, 059, 609.
of rivers, 643.?
Development, examples of law
of, in the earth's his¬
tory, 739.
Devonian age, 265, 750.
and Carboniferous uncon¬
formable, 304.
and Silurian united b\
the Ludlow beds, 264.
ill New England, 469.
thickness of rocks of, 386
wanting in Dakota, 245.
Devon limestone, 294.
Diabase, 77,? 79.?
Diadema serial)', 453,* 464.
Diailage, 60.?; 82.?
Diamonds, age oi, 413.
Diatoms, 66, 166.? 029.*
in flint. 271 * 481.
of Virginia Tertiary, 512.*
Dibranchiates, 156.?
Dicellocephalus lowensis,189.*
magniflcus, 193.
Minnesotensis, 189.*
Diceras, 459.?
Diceras arietina, 459,* 465.
Diclmlmne, 527.? 529.
Diclioiion, 528.
Dichotomizing ribs on Bra
chiopods, 267.
Dicotyledons, 167.?
Dictyoneura anthracopliila.
358*
Dictyocha Crux, 512.*
Dictyopteris, 355.
Diilelphys, 424,? 529.
Dicstian group, 523.
Digitigrades, 422.?
Dikes, formation of, 703.
structure of, 122.?
of Connecticut valley, ori¬
gin of. 703.
Dimyaries, 157.?
range of, in time, 401.
Dinictis, U. Missouri, 519.?
Dinornis giganteus, 578.
Dinosaurs, 346,? 452.
range of, in time, 572.
Dinotliere (D. gigauteum)
528*
Diorite, 78,? 89 ?
Dioritic scliist, 78.?
Dip, 105.?
of Triassic beds, 4.32.
Dipliyphyllum stramineum,
' 270.
Diplazites, 355.
Dijilotegium, 356.
Diploxylon, 356.
Diprotodon, 424,? 566.
Dipters, 421 ?
Dipterus macrolepidotus,298.*
Dirt-beds of the Coal-mea¬
sures, 326.
Discina, 184,? 186, 187, 399.
lamellosa, 183*
Dislocations, 103.?
See Disturbances.
Distortions of fossils, 109.?
Disturbances tiller E Silurian,
226.
782
INDEX.
Disturbances after the Paleo¬
zoic, 403.
preceding the Carbonife¬
rous, 320.
after the Mesozoic, 502.
after theTertiary, 530,533.
in the age of Man, 5<StS.
Diversity of rocks in different
regions, 377.
Dodo, 573.*
Dolerite, 89.§
Dolomite, (13,§ 85.?
Doniite, 88.?
D'Orhigny's subdivisions of
Jurassic, 448.
subdivisions of Cretace¬
ous, 480.
D'Orbigny on thickness of Me¬
sozoic, 403.
Dorcatherium, U. Missouri,
519.?
Dorsibrancliiates, 154.?
Drepanodon, 4J. Missouri, 519.
Drift, 535.?
in Arkansas, 754.
in Europe. 540.
in Missouri, 753.
in North America, 536.
in South America, 540.
modified, 530, 549.
origin of, 541.
See, further. Glacial and
Ulacigr.
Drift-sand hills, 628.
Droniatheriuin sylvestre, 426,
420.*
Dryopitliecus, 529.?
Dudley limestone, 260.
Dugoiig, 423.?
Eocene, 529.
Dunes, 629.?
Dust-showers, 629.
Dyas. See Permian.
Dyestone group, 384.
Dynamical Geology, S,? 003.
agencies intensified in
the Post-tertiary, 570.
Dysaster, 160.?
canaliculatus, 464.
ovalis, 465.
ringens, 464.
Dysyntribite, 82.?
Eagre, 653.?
Earth, relation of, to the uni¬
verse, 3.
form of, and arrangement
of land of, 10.
increase in mass of, above
the water's level, after
the Mesozoic, 569.
evolution of features of,
731.
system in reliefs of, 23.
system in the courses of
feature-lines of, 30, 731.
Earth's crust, effects on, of
contraction, 718.
development, examples of
law of, in geological
history, 739.
Earthquake oceanic waves,
655, 729.
Earthquakes, nature and ori¬
gin of, 728.
evidence from, of the
earth's internal liquid¬
ity, 684.
East Indies, trends of islands
in, 37.
Eatonia singularis, 254,* 255.
Ebb-and-fiow structure, 93.?
Ecculiomphalus Canadensis,
192.
intortus, 192.
Echidnus, 424.?
Echinoderms, 158,? 159.
range of, in time, 400.
Echinoids, 159.?
Echinoneus, 160.?
Echinorhinus, California, 521.
Echinostachys cylindriea, 434.
oblonga, 434.
Echinus, 148.*
grannlatus, 552.
Eclogite, SO.?
Edentates, 42.3.?
characteristic of Post-ter¬
tiary, of South America,
565."'
earliest of, 528.
range of, in time, 572.
Ehrenlierg, on Diatoms of
Richmond, 512.
on dust-showers, 629.*
on green-sand, 749.
on Polycystines, 612, 749.
Eifel, Devonian in, 295.
Elaiacrinus, 274.
Elephant family, range of, in
time, 572.
Elephas Americanns, 561.*
primigenius, 560, 577.
Miocene species of, 529.
of U. Missouri, 522.
Elevations, causes of, 716.
of Pacific islands, 587.
Tertiary, in Europe, 533.
See Heights.
Elotherium in U. Missouri,
521.?
Emmons, E., on the Triassic in
N. Carolina, 417, 426,
429.
sections of Azoic by, 141.
Emys, Eocene, 517.?
Enaliosaurs, 346.?
Carboniferous, 351.
Jurassic, 451.
range of, in time, 4o2, 572.
Encrinal limestone, 252, 281.
lincrinites, 161.?
Encrinurus levis, 262.
Encrinus liliiformis, 148,*
435,* 438.
Endoceras, 214.?
longissimum, 215.
proteifonne, 214.?
Endogens, 167.?
Endojiachys Maclurii, 517.
England, Carboniferous in,
352.
Cretaceous in, 479.
Devonian in, 294.
disturbances in. 412.
Jurassic in, 446.
England, Post-tertiary, life of,
560.
Permian in, 372.
Subcarboniferous in, 318.
Tertiary in, 522.
Triassic in, 433.
geological map of, 354.
Entomostracans, 153.?
range of, in time, 401.
Entomozooids, 749.?
Eocene, 506,? 522, 524.
of Europe, climate of, 534.
of N. America, climate of,
534.
plants of, in Europe, 525,
534.
See, further, Tkrtiart.
Eocidaris, 374.
Eolian limestone, 391, 392.
Eosaurus Acadianus, 352.*
Eospongia Roemeri, 209.
varians, 209.
Ephemera, 420.?
Epiaster elegans, 478.
Epidote, 07.?
Epiornis. See J3piornis.
Epithemia Argus, 631.*
gibba, 631*
gibberula, 631 *
longicornis, 631 .*
Epoclis, origin of, 737.
Equisetum, 166,? 334.
oolumnare, 420.
Equus, 529.
in Missouri Pliocene, 522.
Ericulus, 463.
Eriuaceus, 529.?
Erosion by action of rivers,
635.
by oceanic movements
655.
by drift sands, 631.
extent of, over continents,
679.
increase of, in the Post-
tertiary, 570.
in New England, 679.
over continents, when
near the ocean's level,
665.
topographical effects of,
680.
of the channel of Niagara,
590.
of the channel of the Co-,
lorailo, 569, 638.*
Eruptions, volcanic, 694, 696.
Eryon arctiformis, 461.*
Eschara, 158.*
Esopus millstones, 230.
Estheria Keuperiana, 438.
minuta, 430,* 438.
ovalis, 426*
ovata, 426*
parva, 420.*
Ettingsliausen, climate of Eu¬
rope in the Tertiary.534.
Eucalyptocrinus decorns, 261.
Eucyrtidium Mongolfieri, 749.
Eugnathus, 427.
Eumys, in U. Missouri, 521.?
Eunotia ampliioxys, 631.*
granulata, 631.*
INDEX.
783
Eunotia levis, 6.31 .*
tridentula, 031.*
zebrina, 031.*
Eunice, 155.
Euoinphalus profundus, 255.
Euphotide, 79, 80-2
Eurite, 70-2
Europe, life of, in the Post-
tertiary, 559.
geography of, 265, 318,
412, 405, 494, 502, 533,
508.
Tertiary, climate of, 534.
Tertiary species of, more
numerous than those
of America, 526.
trends of land of, 38.*
and America, difference
of, in progress, 393, 535.
Eurylepis, 350.£
tuberculatus, 350.*
Eurypterus, 259.(1
remipes, 253, 254,* 262.
Enrysternum IVagleri, 462.
Excrements of animals, 609.
Exogyra, 450,2 472.
arietina, 474.*
Boussingaultii, 487.
costata, 474,* 479.
levigata, 487.
Yirgula, 459,* 465.
first of, 450.
Expansion, change of level
from, 718.
Extermination of tribes, fami¬
lies, genera, species, 203,
259, 303, 397, 504, 601.
Exterminations, modern ex¬
amples of, 578.
Fagus ferruginea, 514.*
Falilunian beds, 523.
Falls of the Ohio, coral reef
of, 272.
Fasciolaria, first of, 484.
buccinoides, 477.*
rhomboidea, 522.
Fault at Montmorency, 227.
Faults, 106.2
origin of, 727.
in the Appalachians, 198,
407, 720.
Fauna of an age, harmony in,
396, 501, 598.
Favistella, 303.
stellata, 220.*
Favosites, 162.2
basaltica, 270.
Goldfussi, 273.*
Gothlandica, 242, 249, 262,
280.
Niagarensis, 239,* 240,
242.
polymorplia, 262.
family of, a comprehen¬
sive type, 756.
Feejee Islands, 023.
Feldspar, 55.(1*
Felis, 529.(1
atrox, 563.
spelsea, 577.
in the Upper Missouri
Pliocene, 522.
Fenestella prisca, 236.*
Fenestella retiformis, 37 4.
Ferns, 166.§
in coal shales, 327 , 338,(1
373, 419.
Ferruginous sandstone, 382.
Fingal's Cave, 702.
Fiord valleys, 541, 543.
Fir-cones, 419.
Fishes, 152.(1
classification of, 2T7.§
first of, 264.
first American, 272, 276.*
number of living, 575.
range of, in time, 402.
first Osseous, 473,* 480.*
in Catskill beds, 293.
in the Devonian, 302.
Fish-teeth in the Lower Silu¬
rian, supposed, 395.
Fissures, dikes lormed in, 703.
See Fractures.
Flabellina rugosa, 164,* 4S3.*
Flabellum Wnrlesii, 517.
Flexibility of ice, 673.
of rocks, 721.
Flexures. See Plications.
Flint, 55.(1
in Cretaceous, 4S0.
origin of, 488.
Flint implements, localities of,
582.
Flood-plain of rivers, 555, 641.
Flora. See Plants.
harmony of, in ages, 302,
396, 501, 598.
Florida, elevation of, 531.
Tertiary in, 509.
trend of, 37, 147, 736.
Flowers, fossil, 341.
Fluccan, 124.(1
Fluor, spar, 65.(1
Flustra, 158.(1
Fluvio-marine formations, 659.
Folds, 103.(1*
8ee Plications.
Footprints in Potsdam beds,
185*
in the Subcarboniferous,
315.*
in tire Triassic, 415. 421,*
436.*
Foraminifers, 163.g*
Eorbes, E., on colored fossil
shells, 264, 319.
Forbes, J. D., on glaciers, 673.
Force of running water, 635,
650.
Forces, the same through geo¬
logical history, 7.
Formation, 92.(1
Forest-marble group, 448.
Forest-regions, distribution of,
46.
Fossilization, methods of, 611.
Fossils, 5,(1 69, 200, 608.
chronological data, 115 §
American localities of,
757.
obliteration of, by meta-
morphism, 706.
Fox Hill groups, 469.
Fractures, system in, 19,* 20,*
21.
origin of, 725.
Fractures, direction of, as re¬
lated to the tension
causing tlieni, 726.
Fragmental rocks, 70.jl
France, Carboniferous in, 352.
Cretaceous in, 479.
disturbances in, 412.
flint implements in, 5S1.
Jurassic in, 447.
Subcarboniferous in, 318.
Franklinite, 84.(1
Freezing, effects of, 667.
Fresh-water deposits, none in
the Devonian, 300.
Frondicularia annularis, 16-1.*
Frontispiece, reference to, 283-,
333.
Fruits, Carboniferous, 337,*
341.
Tertiary of Brandon, 514.*
Fucoids, 167,2 118,* 208,* 219,
233,* 235,* 270.*
Fucoides Cauda-galli, 270,
271 * 283, 289.
duplex, 187.
Ilarlani, 231.*
Fuller's earth-group, 448.
Fungia, 163,(1 618.2
Fusulina, 164,* 343.
cylindrica, 164,* 347, 357.
elongata, 347.
Fusus Newberryi, 477.*
Gabbro, S2.g
Galapagos Islands, 499.
Galena, 64.(1
Galena limestone, 206.
Galeocerdo latidens, 519, 521.
Galerites, 160.2
Gait limestone, 246.
Gampsonyx fimbriatus, 358.*
Ganges, sediment of, 644.
Ganocepliala, 345-2
Ganoids, 278.2*
a comprehensive type, 597.
culmination of, 497.
range of, in time, 402, 572.
of tlio Devonian, 302.
Ganoid teeth, structure of,
280*
Garnet, 57-2*
Gars, 278.2
Gaspe, Hamilton at, 282.
Oriskany at, 266.
titled beds at, 227.
Gasteropods, 156.2
culmination of, 397.
dental apparatus of, 272.
395.
range of, in time, 401.
Gastridium vetustum, 517.
Gault, 480.
Gay Head, fossils of, 511.
Gaylenreuth Cave, 559.
Genera commencing in the
Cretaceous, 499.
Geneia commencing in the
Jurassic, 499.
Genesee Falls, section at, 90,
231.
shale, 280.
Geoclinal valleys, 722.§
Geographical distribution of
life, principles in, 606.
784
INDEX.
Geographical distribution of
oceanic species,as illus¬
trated by tlie I'll} Bio¬
graphic Chart, 41.
Geography, American, in the
Carboniferous, 304.
American, in the Catskill,
293.
American, in the Cham-
plain epoch, 552.
American, in the Che¬
mung,
American, in the Cornife-
l'ons, 278.
American, in the Creta¬
ceous, 489.
American, in the Devo¬
nian, 299.
American, in tlie Hamil¬
ton, 280.
American, in the Jurassic,
405.
American, in the. Lower
Iieldorberg, 'dan.
American, in tlie Niagara,
24:1.
American, in the Oris-
kany, 2liS.
American, in the Per¬
mian, 471.
American, in the Pots¬
dam, 196.
American, in the Salina,
249.
American, in the Subcar-
bonilerous, 310.
American, in the Tertiary,
ni 10* 508.
American, in tlie Trenton
and Hudson periods,
222.
American, in the Triassic,
449.
American, through the
l'aheo/.oic, 380.
European, in tlie Creta¬
ceous, 491.
European, in the Devo¬
nian, 301.
European, in the Juras¬
sic, 40a.
European, in tlie Tertiary,
fits').
of the Hesozoic, 493.
of the Post-tertiary, 540.
Geology, objects of, 2,?' 4.
Georgia, Cretaceous ill, 409.
level of, near Milledge-
ville, 31.
Vt., rocks at, 175.
Geosaur, 340,? 402.
Geoteutliis, 454,? 404.
Germany, Carboniferous in,
352.
Cretaceous in, 481.
Devonian in, 295.
Jurassic in, 447.
Snbcarhoniferous in, 318.
Triassic in, 433.
Geysers, 700.g
siliceous deposits from,
70S.
Giants' Causeway, 702.
Gieseckite, 61.?
Glabella, 188,?
Glacial epoch, 535.?
scratches, 538, 070, 753.
theory of tlie Drift, 543.
Glacier of Mohawk Valley. 753.
of Penobscot Day, 545.
of Switzerland, reaching
to the .1 urns, 545.
of the Susquehanna, 753.
of Zermatt, 070 *
Glaciers, characters, origin,
and effects of, Gt>7,*
753.
increase of, in the Post-
tertiary, 570.
of Connecticut Kiver and
Hudson Diver valleys,
540 544
Ghiris, flsl'ies at, J)20.
Glauconie grossiere, 523.
Glauconite, -47 O.jJ
See Green-sand.
Glen Poy, hem lies of, 558.?
Globigerina rubra, 104.*
Glyphea duhia, 35.8.
Glvptocriims, 191.
decadactylus, 220*
Glyptoilon, 423.?
clavipes, 500.*
Gneiss, 7 <5.? 78.? 81.?
Goeppert on number of plants
in the Palmozoic ages,
295.
Gold-hearing veins, 715.
Gold-quartz, age of, 413.
Gomphonema gracile, 031.*
Goniatites, 284.? 303, 399.
Marcellensis, 235 *
parvus, 349.
politus, 349.
punctatus, 285.
retrorsus, 297.*
unianguiaris, 285.
first of, 284.
range of, in time, 401.
Gonioceras aneeps, 214, 215.
Gorgonia, 103.?*
Gothland. See Scandinavia.
Niagara in, 200.
Granimatophora marina, 100,
512*
Grammysia eingulata. 204.*
Hamiltonensis, 284.*
Grammostomum phylli ides,
104,* 474.
Granite, 75,? 76.?
Granulite, 70.?
Graphic granite, 70.?
Graphite, 04.?
Graptolites, character and re¬
lations of, 162,? 190.?
last of, 235.*
range of, in time. 398,400.
Graptolithus amplexicaulis,
212 *
Clintonensis, 236.*
Ilallianus, 180*
Logani, 190*
pristis, 191,* 220.
Grasshopper, 420.?
Gravel, 74.?
Gray hand, 232.
Great Britain. See England.
Greenland, glaciers of, 008.
Greenland, recent changes of
level in, 587.
Green Mts., an island in the
Oriskany period, 208.
in tlie Paleozoic, 388.
Green-sand, composition of,
470.
connection of formalion
of, with lthizopods, 749.
Cretaceous, 408, 470, 480.
L. Silurian, 174, 170, 210.
lthizopods in, 201, 210.
Greenstone, 78.?
(ires bigarre, 43.3.
de Pontainebleau, 523.
des Vosges, 412.
Grindstone grit; 73.?
Grit, 73.?
Groovings. See Scratches.
Gryllacris, 358.?
Grypliea ureuata, 449, 453,*
404.
Cvmliium, 453, 404.
dilatata, 459,* 405.
lateralis, 479, 437.
Pitched, 474,* 478.
vesicuhiris, 474 * 479, 4S7,
483.
Tomer, 479.
first of, 450.
last of, 472.
Gryphite limestone, 449.
(iuadaloupe, skeletons of, 580,
581 .*
Guano, 00.?
Gueiph formation, or Gait, 240.
Gulf border region, 413.
Gulf of Mexico in tlie Creta¬
ceous, 490*
of Mexico in the Ter¬
tiary, 5:'.0*
of Mexico in tlie Permian
Period, 371.
Gulf Stream, 41, 200, 051, 058.
(iuvot, A., on Africa, 28.
on Cosmogony, 742.
011 the Great Swiss Gla¬
cier, 545, 752.
on the Post-tertiary of
Switzerland, 577.
Gymnosperms, 100?
divisions of, 418.
Gypseous group of Montmar-
tre, 523.
Gypsum, 03,?* 85.?
mode of formation of, 248.
443.
formed on coral islands.
443.
GyrocerasBurlingtononsis.314.
Gyrodus umbilicus, 279.*
Hadrosaurns Foulkii, 473.
Hague, A., on effects of oceanic
currents, 001.*
011 formation of gypsum
on a coral island, 443.
Haliealyptra finibriata, 749*
Halieore, 423.?
Ilalitherium, 529.?
Hall, J., on the commencement
of the Devonian, 208.
on Conularia, 490.
011 rocks of Iowa, 381.
INDEX.
785
Hall, J., on Carboniferous un¬
conformable with infe¬
rior strata, 320.
Halloysito, GO.g
Halonia, 356.
pulchella, 335.*
Halysites, 211, 239,* 253, 303.
catenulata, 238, 239,* 240,
242, 243, 249, 201, 262.
gracilis, 220.*
last of, 253.
Hamilton beds, section of, on
Lake Erie, 281.
group, 280.
period, 280.
Hamites, 472.$
attenuatus, 485.*
Fremonti, 478.
Harmony of the Fauna and
Flora of an age, 302,396,
501, 598.
Hastings Sand, 448.
Hawaian group, map of, 31.*
group, origin of, 701.
Hawaii, erosion on, 637.
map of part of, 688,*
696.*
profile of, 687 *
volcanic action on, 687,*
695,* 701.
Hayden, on fresh-water lakes
of the Upper Missouri
in the early Tertiary,
531.
on dip of strata in the
Rocky Mts. and Upper
Missouri region, 532.
See, further, Meek.
Hayesine, 80.{!
Headon Hill sands, 522.
Heat, sources of, 681.
internal, of globe, 682.
depth, at any place of the
plane of mean, 682.
agency of, in metamor-
phism, 707.
Heavy spar, 65 .))
Height about head-waters of
the Mississippi, 22.
mean, of Himalayas, 26.
of Cayambe, 22.
of Chimborazo, 22.
of Cotopaxi, 22.
of Hawaian mountains,
688.
of L. Titicaca, 22.
of Pichinoha, 22.
of some volcanoes, 685,
686, 687.
Heights of plateaus, 21, 22.
of terraces, 550, 551.
Helderberg, Lower, 251.
Lower, American species
of, occurring elsewhere,
261.
Upper, limestones, 269.
Upper, a coral-reef period,
272.
Helicoceras, 473.
Mortoni, 479.
Helicotoma planutata, 213.*
uniangulata, 192.*
Heliolites, 303.
Heliolites spinipora, 240.*
porosa, 280.
pyriforntis, 261.
Heliophyllum llalli. 284.*
Helix, 160.*;)
Helminths, 155.;)
Helvetian group, 523.
Hematite, 65,j) 83.;)
Hemiaster, Eocene, 617.
Humphreysianus, 479.
Hemicidaris crenularis, 405.
Purbeckensis, 465.
Hemipristis Serra, 521.
Hemipters, 420.^
Hemitrochiscus paradoxus,
375.
Hempstead beds, 523.
Herbivores, 422.;)
range of, in time. 672.
marsupial, 424.
Herseliel, theory of metamor-
phism, proposed by, 711.
Heterocercal fishes, 277.;)
fislies. last of, 436.
Heterohyus, 529.))
Heulandite, 02.))
Ililgard, on Mississippi Ter¬
tiary. 508, 509.
Ilils-conglomerat, 480.
Himantidium Arcus. 631.*
Monodon, 631.*
zygodon, 631.*
Ilipparion, 423.§
U. Missouri, 519, 522.
Ilippopodium ponderosum,
423.
Hippopotamus, 529, 559, 577.
Hippotlieriuni, 529.
Hippurites, 47 2.ji
dilatatus, 484.*
organisans, 487.
Texanus, 475.
Toucasianus, 484*
Hippnrite limestone, 480.
Historical Geology, S.j)
History, nature of subdivi¬
sions in, 125.
Hitchcock, E., on Upper Ilel-
derherg in Mass., 270.
on footprints, 425.
on tufa in Triassie. 430.
on theBrandon lignite,510.
on the Drift, 537, 539, 540.
on terraces, 567.
Hitchcock, E., Jr., on Clatli-
ropteris, 420.
Hog family, Tertiary, 529.
Holaster simplex, 474, 478.
Holopea dilucula, 192.
Holoptyeliius, 280, 298.*
Ainerieaiius, 293.*
Taylori, 293*
Holothuroids, 159.j)
Homaeosaurus, 462.
Homalonotus armatus, 297.
delpliinocephiilus, 241,*
242, 261.
Homocercal fishes, 277
Hopkins, on force of running
water, 635.
on directions of fractures,
72li.
Hornblende, 59.j)
51
Hornblende rock, 78.))
Hornstone, 65.))
in Corniferous, containing
Protophytes, 269.
origin of, 270, 271, 377.
Horse, 124.g
Horses, Post-tertiary, 562.
Hot springs, 700, 710.
Hubbard, O. P., on pot-holes in
New Hampshire, 679.
Hudson period, 217.
period, note on, 750.
River, in existence, 300.
River shales, 217.
River valley, submarine
continuation of, 441.
slates, Calciferous in age,
174, 176. 750.
Humphreys and Abbot, on the
Mississippi River delta,
Vc., 034, 647. 662.
Hungary, Carboniferous in,
352.
Hunt, E. B., on Carboniferous
temperature, 363.
on formation of the Flo¬
rida reefs, 755.
on rate of growth of
corals, 754.
Hunt, T. 8., analyses of shell
of recent Lingula, 68.
analyses of actinolite
rock, 78.
analyses of petrosilex and
euphotides, SO.
analyses of schillerite and
ophiolite, 82.
analysis of chert, S3,
analysis of an Ortlioceras,
84.
analysis of glauconite,470.
on thickness uf Calcife¬
rous, 176.
Huron group, 381.
Iluronia vertebralis, 224.
Iltironian, 142, 385.
Huxley, on Rhizopods of N.
Atlantic, 612.
Hyaena, 520.;)
crocuta, 560.
spelie, or Cave U wen a,
559, 581, 583.
Hyamaretos, 529.J
Ilymnodon, 529.g
U. Missouri. 519*
Hyliodus minor, 277,* 436.
Mougeoti, 438.
plicatilis, 277,* 430.
Hybodonts, 278.*
culmination of, 497.
I range of, in time, 402,572.
Hydra, 102.))*
Hydraulic limestone, 84.§
Hvdroids, 162 .;)*
Ilyla-osaur, 316.)) 452.
Hylonomus. 352.;)
Ilymenocaris vermicauda,
194*
Hymenopliyllites, 338, 330,
355.
furcatus. 342.
Hildrethi, 340,* 342.
spinosus, 342.
786
INDEX.
Hvmenopters, 421 .?
Hyopotamus, 529.?
Hyperite, 78.?
Hypanthocrinus decorus, 242.
Hypersthene, 00.?
llypogene rocks, 138.
Hypostome, 188.?
Ilypsiprvmnus, 424.?
Hyracotherc, 526, 529.?
Hystrix, 529.
Ice of rivers and lakes, effects
of, 667.
See, further, Glaciers.
Icebergs, origin and action of,
677.
transported by the Labra¬
dor current, 542, 058.
transportation of stones
by, 659.
Iceberg theory of the Drift,
541.
Tc.hthyocrinus levis, 240,*
'261.
Ichthyosaurs, 451.?
Arctic, 738.
Ichthyosaurus, communis,
451, 456*
range of, 487.
Idiochelys Wagneri, 462.
Idocrase, 57.?
Igneous action in Potsdam
period, 195, 389.
action in Mesozoic, 430.
eruptions, non-volcanic,
702.
eruptions. See Volcanic.
interior of the globe, evi¬
dences of, 682, 701, 741.
rocks, 70,? 86.?
Iguana, 346.?
Iguanodon, 346,? 452.?
Mantelli, 464.*
range of, in time, 487.
Illrenns Arctnrus, 210.
Barriensis, 241,* 242, 261.
crassicauda. 210.
Davisii, 216.*
Illinois, Carboniferous in, 323.
Hamilton in, 281.
Hudson in, 218.
lead-mines of, 207.
Millstone grit in, 322.
Niagara in, 238.
Oriskany in, 266.
Permian in, 371.
rocks of, 382.
Subcarboniferous in, 307,
30.8.
uplifts in, 304.
Upper Helderberg in, 270.
Illinois and Appalachian coal
measures, equivalency
of, 329.
Imbricates, 280 ?
India, Tertiary, Mammals of,
529.
Indiana, Carboniferous in, 323.
Hamilton in, 282.
Millstone grit in, 322.
Niagara in, 270.
Upper Helderberg in, 270.
Individualities in nature, 1.
Infusoria, relations of, 16:',.?*
167,?* 749.?*
oceanic, 012, 664.
Infusorial bed of Barbadoes,
612.
bed of Uilin, 524.
bed in Virginia, 511, 512.
dust-showers, 629*
Ink-bag of Calamary, 451.
Inoeeramus, 472.?
aviculoides, 478.
Bambini, 479.
biformis, 479.
Capulus, 478.
eonfertim-annulatus, 478.
Crispii, 487.
latus, 479, 487.
mytiloides, 487.
problematic™, 474,* 478,
487.
pseudo-mytiloides, 478.
sublcvis, 479.
umbonatus, 478.
Insects, 152.?
classification of, 420.
number of living, 575.
range of, in time. 402.
Carboniferous, 350, 356,
7 51 .*
Devonian, 286.
tracks of, in Triassio, 427.*
Inseetivores, 423.?
range of, in time, 572.
marsupial, 424.?
Iowa, Carboniferous in, 323.
Cliazy in, 205.
Chemung in, 288.
Clinton in, 233.
Hamilton in, 281.
Hudson in, 218.
rocks of, 381.
Salina in, 247.
Subcarboniferous in, 367.
Trenton in, 206.
uplifts in, 304.
Upper Helderberg in, 270.
Ireland, Carboniferous in, 353.
Devonian in, 294.
Jurassic in, 447.
Permian in, 372.
Subcarboniferous in, 318.
Ireleth slates, 260.
Iron, 53.?
Iron ores, 65,? 83,? 84.?
ore, fossiiiferous, 266.
ore, in Carboniferous, 329.
ore, argillaceous, in Clin¬
ton group, 244.
ore, in Triassic, 417.
period, 583.
Ironstone, 329.
Iscliypterus, 427.
Isehyromys, U. Missouri, 521.
Isocrymal chart, 42.?
Isis nobilis, 67.?
Island-chains, curves in, 30.
31* 35,* 36.
in the Pacific, 31,* 33.*
Isopods, 153.? 349.
Isothermal chart of the ocean,
42.?
line of 60° in the Tertiary
in N. America, 534.
Itarolumite, 83.?
Italy, Cretaceous in, 481.
changes of level in Sera-
pis, 588.
Ives, on tlie Colorado, 569.
638*
Jackson epoch, 506, 508, 517.
Janira heniicyclica, 522.
Jasper, 55,? S3.?
Jelly-fish, i58.?
Jet, 68.?
Jewett, E., on the age of the
Catskill beds, 750.
Jointed structure, 99.?
Joints, origin of, 728.
systems of, in Shawan-
gunk Mts., 230.
transverse, in Triassic,
432.
Juras, boulders on, 545.
elevation of, 733.
oblique scratches on, 752.
Jurassic period, Amor., 444.
period, foreign, 446, 751.
on the Atlantic border,
443.
reptiles in the Arctic, 738.
Kanawha Salines, 330.
Kangaroo, 424.?
Kansas, Carboniferous in, 323.
Permian in, 369.
Kaolin, 66.?
Kaskaskia limestone, 307.
Keiloway rock, 448.
Kendal tilestones, 260.
Kent's Cave, 559.
Kentucky, Carboniferous in,
322. 323.
coal beds, thickness of.
323.
Hamilton in, 282.
Millstone grit in, 322.
Subcarboniferous in, 306.
Upper Helderberg in, 270.
Keokuk limestone, 307.
Keuper, 433.
Key West, oolitic coral rock
at, 201, 752.
Kilauea, 688, 689.?
Kimmeridge clay, 448.
Kimmeridgian group, 449.
Kinderhook group, 308.
Kingdoms of nature, 1.
Kingsmill Islands, 616.*
Kirkdaie Cavern, 559.
Koninckina, 1S3.?
Knorria, 356.
imbricata, 342.
Kupferschiefer, 372.
Kyanite, 58.?
Labrador, Potsdam in, 175.
current, 41, 651, 658.
Labradorite, 56.?
Labyrinthine structure of
Ganoid teeth, 280.*
Lnbyrinthodonts, 34.5,? 395.
a comprehensive type,
597.
culmination of, 497.
range of, in time, 402, 572.
INDEX.
787
Laliyrintbodon giganteus,
430,* 438.
Laccopteris falcatus, 420.
germinans, 420.
Lacertians, 340.?
culmination of, 498.
range of, in time, 402.
Laekenian group, 023.
Lagomys, 520.(1
Lagrange group, 509.
Lakes, positions of, 23.
change of level in surface
of, 002.
fresh-water, of Tertiary,
over U. Missouri region,
531.
the great of N. America,
origin of, 109.
■without outlets, usually
salt, 23.
Lake Cliamplain outlined. 229.
Oliamplain an arm of the
sea in the Post-tertiary,
549, 552.
Superior Azoic, 137.
Superior copper, 177, 195.
Superior Potsdam beds,
174, 199.
Superior Primordial trap,
195, 199.
Superior sandstone, 380.
Lake-hahitations, Swiss, 582.
ates, 157.?
Laminated structure, 93.?
structure, cause of, 727.
structure of glaciers, pro¬
duction of, 074.
Lamination, oblique, of layers,
665.
,477.
acuminata, 487.
elegans, 277,* 517.
Land, arrangement of, 10, 13.
mean height of, 15.
Land-plants. See Plants.
Land-snails, first of, in Carbo¬
niferous, 346, 347.
Land-slides, 649.
Laramie Mts., dip of strata
near. 532.
See Missouri, Upper.
Laurentian, 142.
Lava, 89,? 085,? 690.?
Layer, 91.?
Lead-mine's in Illinois and
"Wisconsin, 207.
in Missouri, 177.
in the Oneida, 23,0.
in the Trenton, 207.
Lebanon Mt., fishes of, 529.
Lecanoerinus elegans, 212.*
Leelaire limestone, 247.
Leda, 399.
multilineata, 517.
Portlandiea, 552.
Leda clays, 552.
Leguminosites Marcouanus,
471*
Leidy, mammals of the Upper
Missouri, 515, 519, 522.
Leperditia alta, 255.*
Anna, 193*
Leperditia Baitiea, 242, 262.
Canadensis, var. nana.
211*
cylindrica, 233.
Pabulites, 215*
Josephiana, 215.
Lepidodeudrids, 395.?
Lepidodendron, 334,? 356, 363.
Chemungensis, 750.
clypeatum, 335.*
Gaspianum, 283.
obovatum, 335.*
primaivum, 282.*
Sternbergi, 334.
Yeltheimianum, 342.
IVorthianum, 342.
Lepido ganoids, 2i9.?
Lepidoids, 280.?
Lepidolite, 57.?
Lepidopliloios, 356.
Lepidophyilum, 356.
Lepidostrolms, 335.? 356.
Lepidopters, 420.?
Lepidosteus, 67, 280.?*
osseus, 279*
Lepidotus, 517.
Lepta-na, 184.?*
depressa, 261.
incrassata, 210.
Moorei, 453* 464.
plicifera, 210.*
sericea, 213* 216, 220,224,
237.
transversalls, 240,* 261.
last of, 450, 495.
range of, in time, 495.
Leptarctus, U. Missouri, 519.?
Leptauchenia, U. Missouri,
519.?
Leptochoerus, U. Missouri, 521.
Leptoccelia disparilis, 240.*
Leptynite, 76.?
Lepus, 529.?
Leslev, J. P., sections by, of
Coal measures in Pa.,
331, 332.
map of axes of flexure in
Pennsylvania, 406.
on fault at C'liambers-
burg, Pa., 408.
on topographical effects
of erosion. 680.
on faults in southwestern
Virginia, 72(1.
on Glacier-scratches in
Pennsylvania, 753.
work by, on Coal and its
Topography, 330.
Lesquereux on equivalency
of coal beds, 332.
table of coal plants, 355.
on Tertiary plants and
fruits, 513, 514.
Leucite, 57.?
Leucitopliyr, 80.?
Levant series, 379.
Level, changes of, in the bot¬
tom of the ocean, vary
the water-line along the
continents, 723.
origin of changes of, 716.
oscillations of, in the Post-
tertiary, 569.
Level, recent changes of, 586.
See, further, Elevations
and Height.
Lias. 448.?
Liassic epoch, 447.
Libellula, 420.? 401*
Lichas lioltoni, 241*
Trontonensis, 215.*
Lichens, 165.?
Life, earliest species, rank of,
396.
earliest species are water-
species, 395.
extinction of species of,
203, 225, 259, 303, 397,
504, 601.
kinds of, most likely to
become fossilized, 609,
610.
lowest kinds of, the best
rock-makers, 611.
materials of rocks from, 66
number ol' existing spe¬
cies, 575.
number of species of, in
L. Silurian, 225, 226.
origination ol' species of,
601.
products contributed by,
to rock-formations, 608.
system of progress of, in
the course of geological
time, 592.
relation of progress in, to
the physical history of
the globe, (iOO.
protective effects of, 604.
transportation of seeds,
vermin, by, and
destructive effects of,
605.
Life, oceanic, distribution of,
illustrated by the Phy¬
siographic Chart, 44.
systenilcss, 596, 597.
Life, in Carboniferous, 332.
characteristic of the Cc-
nozoie, 571.
in Cretaceous, 470, 481,
492.
in Hudson period, 219.
in Jurassic, 449, 466.
in Lower Ilelderberg, 253.
in the Mesozoic, 494.
in Niagara period, 239.
in tile 1'aheozoic, 394.
in Permian, 373.
in Potsdam period, 202.
in Post-tertiary, 558.
in Post-tertiary of Aus¬
tralia, 566.
in Tertiary, 512.
in Trenton period, 207.
in Trenton and Hudson
periods, 225.
in Triassic, 417 420.
Lignite, 68.?
of Brandon, 510.
Lignitic Territory of Missis¬
sippi, 508.
Tertiary of U. Missouri,
509.
Tertiary of Texas, 509.
788
INDEX.
Lima, 399.
retilera, 349.
Limaria clathrata, 261.
fruticosa, 261.
Limbing bads, 623.
Lime, phosphate of, 65,$ 67.
Limestone, 70,$ 84.$
source of, 201, 377.
of Coral islands, 617, 624,
762.
from corals and shells,
612, 678.
from Rhizopods, 612, 678.
Limonite, 65.$
Limulus, 154
rotundatns, 358.*
Lingula, 158,* 184,$* 399, 495.
acuminata, 187, 191, 193.
antiqua, 187.*
cuneata, 233.*
Davisii, 194.*
lamellata, 242.
nitida, 474.
ovalis, 68.
prima, 187,* 325.
composition of, 186.
Lingula flags, 178, 182, 194.
Lion, Post-tertiary, 563.
Liriodendron, first of, 471.
Meekii, 471.*
Liskeard group, 294.
Listriodon, 529.
Lithographic limestone, 308.
slate of Solenliofen, 449.
Lithological Geology, 8,$ 49.
Lithostrotion basaltiforme,
362.
Canadense, 307, 310, 311.*
mamillare, 311.
Littorina palliata, 552.
Lituites, 214.$
Farnsworthi, 192.
Imperator, 192.
undata, 214.
Lituola nautiloidea, 164,* 483.*
Liverworts, 166.$
Lizards, 346.$
Llandeilo flags, 207.$
Llandovery heds, 260.$
Llano Estacado, 21.
Lockport, N. Y., minerals at,
239.
Lode, 124.§
Logan, IV. E., on fault at
Montmorency, 227.
on subdivisions of Azoic,
142.
section of Azoic by,
140.
Potsdam tracks, 185.
Loligo vulgaris, 150.*
London clay, 522.
Longmynd rocks, 177.
Lophiodon, 423,$, 526, 529.$
Lorraine shales, 750.
Loup Kiver group, 511.
Lower Ilelderberg limestones,
251.
Lower Magnesian limestone,
172.
Lower Silurian. See Silurian.
Lurina acutilineata, 521.
contracta, 521.
Lucina Portlandica, 465.
proavia, 275.
Ludlow beds, 200.
beds, land-plants in, 264.
beds, between Silurian
and Devonian, 264.
Lunatia Ileros, 621.
saxea, 521.
Lychnocanium Lucerna, 749*
Lycopodia, 166,$ 283, 334, 397.
Lycopodites, 366.
Matthewi, 290.
Lydian-stone, 55.$
Lyell, subdivisions of the Ter¬
tiary, 506.
observations on changes
of level in Sweden, 586.
Maclnerodus, U. Missouri. 519.
European, 529, 660.
Mackenzie Kiver in the Creta¬
ceous period, 490.
River-system, 23.
Maclurea Aretica, 206, 224.
Logani, 210.*
magna, 206, 210,* 224.
matutina, 192.
Macrocheilus fusiformis, 349.*
Maenqietalichthys, 275.
iSullivanti, 276.*
Macropterna divaricans, 427.*
Maeropus, 424.$
Maerospondylus, 340,$ 457.$
Macrothere, 528 $
Maerourans, 153.$
Mactra funerata, 517.
lateralis, 521.
rostrata, 405.
Madagascar, TEpiornis of, 580.
Madrepora, 163,$ 618.$
Mississippiensis, 518.
palmata, 66.
Madreporic body, 160.$
Maestricht heds, 480.
Magnesian limestone, 372,381.
Magncsite, 63.$
Magnesium, 52.$
Magnetic iron ore, 83.$
Maguntian group. 523.
Mahoning sandstone, 329.
Maine, Hamilton in, 282.
Lower Ilelderberg in, 252.
Oriskany in, 266.
uplifts in, 304.
MalacozOoids, 749.$
Malmo group, 260.
Malocystis Murcliisoni, 209.*
Mammals, 152.$
classification of, 421.
culmination of the type
of, 571.
number of living, 575.
range of, in time, 572.
Post-tertiarv, large size
of, 55!), 561.
Mammals of the Post-ter¬
tiary cotemporaneous
with Man, 576, 577. 578,
581.
in the European Tertiary.
526.
typical character of Eo¬
cene, 527.
Mammalian age, 505.
Mammoth coal vein, 327.
Man, Age of, 573.
characteristics of, 573.
intellectual character of,
how expressed in his
structure, 573.
anterior limbs not organs
of locomotion, 593.
of one species, 584.
origin of, on one conti¬
nent, 584, 585.
Post-tertiary mammals
cotemporaneous with,
576, 577, 578, 581.
skeletons and other relies
of, 586.*
Manatee, extinction of a spe¬
cies of, 580.
Manalus, 423.$
Mantellia niegalophylla, 457,*
465.
Map of axes of folds in Penn¬
sylvania, 406*
Azoic of North America,
136*
of Connecticut trap ridges,
20* 431*
of Cretaceous N. America,
489.
of England, 354 *
of United States, 133.*
of New York and Canada,
170.*
of Hawaian Islands, 31.*
of Loyalty group, 31*
of Marquesas Islands, 32*
of New Caledonia, 31.*
of New Hebrides, 31.*
of courses of Pacific
chains, 33.*
of submerged border of
continent, 441.*
of Tertiary of N. Ame¬
rica, 530.*
of Tahitian Islands, 32.*
of trap of Connecticut,
20* 431*
Marble, 85.$
Marbles of western New Eng¬
land, 391.
Marcellus shale, 280.
Margarita Nebrascensis, 477.*
Marginella larvata, 517.
Mariacrinus nobilissimus, 253.
Marine formations, 659.
Marl, 85.$ 468.
shell, of Post-tertiary, 549.
Marnes iriseos, 433.
Marquesas Islands, map of,32.*
Marsh, 0. C., on Eosaurus, 352.
Marshall group, 308.
Marsupials, 423,$ 500.
a comprehensive type, 597.
range of, in time, 572.
Martha's Vineyard, Tertiary
in, 507, 510, 511.
Martinia umbonata, 284.*
Maryland, Cretaceous in, 468.
Jurassic in, 472.
Lower Ilelderberg in, 252
Oriskany in, 206.
Tertiary in, 507, 510.
INDEX.
789
Marwood sandstones, 294.
Massachusetts, Calciferous in,
391.
Carboniferous in, 324,325.
Potsdam in, 172.
Potsdam fossils in the
coal measures, 325.
Triassic in, 41(5.
Upper Helderberg in, 270.
Mastodon giganteus, 561,562.*
longirostris, 529.
Oliiolicus. 562.*
tapiroides, 529.
in India, 529.
in U. Missouri, 521, 522.
Mastodonsaurus giganteus,
436*
Matinal series, 379.
Mauritius, Dodo of, 578.*
Mayence basin, 523.
May-IIill sandstones, 260.
Meandrina, 618.?
rate of growth of, 754.
Medina sandstone. 231.
Mediterranean basin, 481.
Medusae, 67, 148.?
Meek & Ilayden on Permian,
370.
on Jurassic, 445.
on Cretaceous, 409.
011 Tertiary of the Upper
Missouri. 509.
Megaceros Hibernicus, 561,
570, 581.
Megalobatrachus. 344.?
Megalomus Canadensis, 249.
Megalomervx, in U. Missouri,
522. "
Megalouyx, 423.?
.Teffersonii, 565.*
Megalosaur. 346.?
Megalosaurus Bucklandi, 452,
462,* 464.
Megaphvtum. 356.
Megastlienes, 421.?
Megatherium, 423.?
Cuvieri, 565.*
Melania, first of, 453.
Nebrascensis, 517.*
Melaphyr, 88 ?
Melonites multipora, 313.*
Melosira crassulata, 630.*
decussata, 630.*
sulcata, 106.*
distans, 630.*
Melville Island, Carboniferous
in. 324.
Memphremagog Lake, Upper
Helderberg at, 270.
Menchikoff Island, 616.
Menobranclius lateralis, 347.?
Menopoma, 344.?
Mercenana violacea, 521.
rapax. 521.
tridacoroides. 521.
Mer de (llace, 668.
Meridian series, 379.
Merhta levis. 254.*
nitida, 240* 261.
sulcata, 254,* 255.
Mervchippus in U. Missouri,
519.? 522.
Mervrodus, in U. Missouri,
519.
Meryeopotamus, 529.
Mesozoic tiling 414.
general facts of, 493.
Metamorphism, 704?
Azoic, 145.
after Palaeozoic, 410.
Metamorphic rocks, 74,? 704.?
Meteoric stones, 3.
Mexican plateau, 21.
Miamia, Bronsoni, 751.*
Miascite, 76.?
Mica, 56.?
schist, 76 ?
Michigan, Calciferous in, 175.
Carboniferous in, 323.
coal-field in, 323.
Clinton in, 234.
Hamilton in, 281.
Hudson in, 218.
iron-mines in. 143.
Niagara in, 238.
Potsdam in, 173.
rocks of, 380.
Saliferous in, 247.
Subcarboniferous in, 308.
Trenton in, 206.
Upper Helderberg in, 270.
Michigan Salt-group, 308.
Micrabacia, 483.
Microdiscus quadricostatus,
189.
Microdon bellistriatus, 284.*
Mirrolabis, 358.?
Microlestes antiipms, 435,
438*
Microsthenes, 421,? 423.
Millepores, 162.?* 618.?
carbonate of magnesia in.
67.
Miller, Hugh, on Devonian in
Scotland, 294.
Millstone grit, 73, 321.
Mineral oil. 756.
Mingan Islands, Calciferous
at, 176.
Islands, Cliazy at, 206.
Minnesota, C'haz.y in. 205.
Potsdam in, 173.
Miocene, 506.? 523.
of Europe, climate of,
534.
of Europe, plants of, 525.
534.
See, further, Tertiary.
Mississippi basin, section of
Paheozoic rocks in, 378.
Cretaceous in, 469.
Tertiary in, 508.
Mississippi River, delta of,
646,* 663.
River, discharge and pitch
of, 633, 643.
River, in the Cretaceous,
490.
River, Tertiary along, "07.
Missouri, Azoic in, 137.
Calciferous in, 175.
Carboniferous in, 323. 326.
Chemung in, 288.
Hamilton in, 281.
Oriskany in, 266.
iron-mountains of. 141.
rocks of, 2,S3.
Trenton in, 206.
Missouri, Snbcarboniferoiis in,
30b, 308.
Upper Helderberg in, 270
Missouri,Upper (including Da¬
kota, Nebraska, Black
Hills, &e.), Azoic in,
137.
ill., Cretaceous in, 469.
id., Carboniferous in, 324.
id., Jurassic in, 445.
id., the. Paheozoic largely
wanting in, 245.
id., Permian in, 369.
id., Potsdam in, 174.
id., Tertiary in, 507, 509.
511.
id., Triassic in, 417.
Missouri River, discharge and
pitch of, 633.
River, in the Cretaceous,
490.
Mitra dumosa, 517.
Millingtoni, 517.
Moa, of New Zealand, 57S.
Modiola angusta, 29 !.*
Pallasi, 375.
Shawneensis, 349.
Modiolopsis modiolaris, 221.*
orthonota, 233.
primigenius, 233.
subalatus, 242.
Molasse of Switzerland, 523.
Mollusks, 148, 155.?
number of living, 575.
number of, in European
Tertiary, 520.
rank of earliest, 397.
Monitor, 346.?
Monkeys, 422.?
Eocene, 527.
range of, in time, 572.
marsupial, 424.?
Monoclinal valleys, 720.
Monocotyledons, 167.?
Monomyaries, 157.?
Monotis, 370.?
coneava, 371.
curta, 446.*
Halli, 371.
Hawni, 370,* 371.
speluncaria, 375.
Monotrenies, 424.?
Monte Bolra, fishes of, 528.
Montlivaltia Atlantica, 474,
479.
earyophyllata, 458*
Montmorency, fault at, 227.
Moraines, 670,? 675.
Mosaic cosmogony, 743.
Mosasaur, :UG? 473,? 482.
Mosasaurus Hofmanni, 480.*
Maximiliani, 478.
Missouricnsis, 479.
Moschus, 529.
Moscow shale, 281.
Mountain-chains, composite
character of, 19.*
Mountain-elevation, systems
of. See System.
Mountain-limestone, 318. ,
Mountains, 15.?
lint small heights rela¬
tively to the size of the
globe, 723.
790
INDEX.
Mountains,courses of the same
or different in the same
region in different pe¬
riods, 721.
origin of, 722.
height of. See Heights.
Mouse, 423.$
Movements in the earth's
crust, 716.
Muck, 614.$
Mud-cracks, 94.$
Mulinia lateralis, 521.
Multungulates, 423.$
Murchison, Permian so named
by, 369.
Silurian so named by, 167.
Siluria, by, 260.
Murchisonia Anna, 192.
Fiellicincta, 192, 213 *
bicincta, 213,* 216.
Boydii, 249.
minima, 349.
subangulata, 371.
last of, 374.
Mus, 529.$
Musc.helkalk, 433.
Musci, 166.(1
Mustela, 529.$
Mutilates, 423.$
Mya arenaria, 552.
Myaeites Pennsylvanicus, 426.
Myalina Kansasensis, 371.
perattenuata, 370.*
subquadrata, 371.
Myliobates, 278.$
Mylodon, 423.$
Harlani, 560.
robustus, 565.
Myophoria, 450.
vulgaris, 438.
lineata, 435,* 438.
Myriapods, 152.$
in the Carboniferous, 346.*
range of, in time, 402.
Myrmecobius, 424,$ 429.
fasciatus, 438.*
Mvrmecophagus, 423.$
Mytilus edulis, 552.
Pallxsi, 375.
rectus, 371.
Shawneensis, 349.
squantosus, 375.
Mystriosaurus Tiedmanni,
457 *
Naphtha. See Petroleum.
Napoleon group, 30S.
Nashville group, 217.
Nassa trivittata, 521.
Natiea iEtites, 517.
clausa, 552.
elegans, 465.
(Irocnlandica, 552.
Heros, 552.
Yieksburgensis, 517.
Naticopsis Pricei, 371.
Natrolite, 62.$
Nautilus, 155*$ 186, 399, 496,
497.
Dekayi, 477,* 479.
elegans, 487.
lineatus, 464.
Koninokii, 319.*
Missouriensis, 349.
Nautilus Permianus, 371.
planivolvus, 349.
Nautilites Vanuxemi, 517.
Navicula ampliioxys, 631*
liacillum, 631*
Lima, 517, 518.
serians, 631.*
Semen, 631.*
Nebular theory, 741.
Necturus, 344.
Neithea Mortoni, 479, 487.
Neocomian, 480.
Neplielin-dolerite, 89.$
Neplieline, 61.$
Nephelinite, 8>j.$
Nerintea, 459.
Acus, 477.
bisuleata, 484,* 487.
fasciata, 465.
(loodhallii, 459,* 465.
Goste, 465.
Texana, 477.*
Nerita, first of, 453.
Neuropterhke, 338.$
Neuropteris, 338,$ 355, 420.
flexuosa, 342.
liirsuta, 338,* 342.
Loschii, 338,* 374.*
Moorii, 342.
range of, in time, 424.
Ntrve, 671.$
Newberry, J. S., on fish of the
Corniferous, 275.*
on fish of Catskill group,
293.
on fish of tlie Subcurboni-
ferons, 315*
on lisli of tire Carbonife¬
rous, 350.*
on fossil flowers and fruit,
341*
on cannel-coal, 368.
on rocks of the tipper
Colorado, 417.
on Cretaceous plants,471 .*
on Tertiary plants, 513.
on the Colorado, 569, 638*
New Brunswick,Carboniferous
in, 324, 353.
Devonian in, 28S.
Millstone grit in, 322.
Subcarboniferous in, 309.
New Caledonia, map of, 31.*
New England, flexures and
faults in, 409.
mostl}- of Palaeozoic age,
409.'
terraces in, 507.*
Newfoundland, Carboniferous
in, 324, 353.
Potsdam fossils in, 189.
New Hebrides, map of, 31.*
New Jersey, Azoic in, 137.
Cauda-galli grit in, 269.
Cretaceous in, 469.
Lower Holderbei'g in, 252.
soundings off coast of, 441.
subsidence of, 587.
Tertiary in, 507, 510.
Triassic in, 4] 6.
New Mexico, Carboniferous in,
324.
Cretaceous in, 469.
Lower Silurian in, 245.
New Mexico, Permian in, 369.
Upper Silurian and De¬
vonian wanting in, 245.
New Red Sandstone. 372, 433.
New York, strata of, a stand¬
ard, 16S.
Azoic in, 137.
Caleiferous in, 175.
Cauda-galli grit in, 269.
Cliazy in, 205.
Chemung ill, 288.
Clinton in, 234.
Coal measures absent
from, 293.
Hamilton in, 2S1.
Hudson in, 218.
Lower Ilelderberg in, 251.
Medina in, 231.
Niagara in, 238.
Oneida in, 230.
Oriskany in, 266.
Portage in, 287.
Potsdam in, 173.
Saliferous in, 247.
Schoharie in, 269.
Trenton in, 206.
Triassic in, 416.
Upper Ilelderberg in, 269.
Utica shale in, 218.
New York harbor, former sites
of, 442.*
New Zealand, Moa of, 578.
Niagara group, 237.
period, 229.
American species in, oc¬
curring elsewhere, 261.
and Clinton, species com¬
mon to, 242.
Niagara River, recession of
Palls of, 238, 590.
River, ancient channel of,
filled with drift, 536.
River, section along, 232.*
Nictaux, Oriskany at, 266.
Niobrara group, 469.
Noctiluca1, 748.$
Nodosaria vulgaris, 164.*
Nodules, phosphatic, 67.$
Noeggcrathia, 338,$ 340, 355.
Halliana, 290.*
minor, 340.*
obtusa, 292.*
Non-marsupials, 421.$
N. American coast, sand-bars
of, 662.
N. America, mean height of,15.
origin of grand features
of, 733.
elevations in, during the
Tertiary age, 530, 531.
in the Cretaceous, map of,
48!).*
recent change of level in,
587.
the continent of Herbi¬
vores, 567, 585.
map of, in the Azoic, 136.*
map of. in the Cretaceous,
489.*
map of, in the Tertiary,
530.*
North Carolina, Cretaceous in,
469.
Triassic in, 416, 417.
INDEX.
791
Norway, Azoic in, 137.
iron-mines of, 141.
Primordial in. 178.
Trenton in, 207.
Norwich Crag, 523.
Notamia loricata, 190.*
Nothosaurus mirabilis, 437.
Schimperi, 438.
Notidatnis priinigenius, 277,*
517.
Notornis, 580.
Nototlierium, 424.g
Novaculite in Arkansas, 322.
Nova Scotia, Carboniferous in,
324, 353.
Clinton in, 235.
Millstone grit in, 322.
Niagara in, 238.
Oriskany in, 206.
Subcarboniferous in, 309.
Triassic in, 410.
uplifts in. 304.
zeolites of, 430.
Nucleocrinus, 274, 303.
Verneuili, 274*
Nucleolites crucifer, 470, 488.
Nucula, 304, 399.
Cobboldias, 521.
divaricata, 521.
Nullipores, 07 .g
Nummulites, i04,g 514, 523.
i)2o,
nunnnularia, 104.*
Nunimulitic beds, 523.
limestone, 523.
Oaliu, chalk in, 488, 755.
map of, .31.*
Obolella, lS4.g
nana, 187.*
Obolus, lK4.*g
Apollinis, 187.* 217*
Labradoricus, 187.
Obsidian, 88,g S9.g
Occident, 13, i4.
Oceans, arrangement of, 11.
depth of, 12.
trends of, 3(3.
relation between the size
of, and the heights of
the borders, 23.
Oceanic currents, 650, 052, 054,
057.
forces, 050.
formations, 059.
movements, system of,39.*
Oculinu, 103.
Mississippiensis, 518.
rate of growth of, 754.
Odontidium pinnulatum, 512,*
031.
Odontocephalus selenurus,275.
Odontoptens, 338,g 339, 342,
355.
cremilata, 342.
Sclilotheimii, 339.*
(Eningen, tislies at, 529.
Ohio, Carboniferous in, 322.
Clinton in, 234.
Hudson in, 218.
L. Silurian in, 22S.
Millstone grit in. 322.
mineral oil in, 7 5(5.
Ohio, Niagara in, 238.
Portage and Chemung in,
288.'
Subcarboniferous in, 308.
Upper Helderberg in, 279.
uplift in, 228.
Ohio Kivor, discharge of. 033.
River, in the Cretaceous,
490.
Oil, mineral, 756.
Oldliamia antiqua, 194.*
radiata, 194.*
Old Red Sandstone, 294.
Olenus micrurus, 194.*
Oliva litterata, 521.
Olivanites, 274.g
Olivella Alahaniensis, 517.
Olivine, 00.g
Omnivores, 423.g
Omphyma turbinata, 203.*
Onchus, 204.g
Oneida conglomerate. 230.
epoch, 230.
Onondaga limestone. 209.
Onondaga salt group, 240.
Oolite, 86.g
Lower and Upper. 448.
of Florida reefs, 754.
Oolitic epoch, 447.
Obtocoids, 420.g
Opal, 55.g
Ophidians, 345.g
Ophileta compacta, 1S7, 192,
193.
complanata, 192.
levata, 192.*
Ophiolite, 82.g
Ophiura, lOl.g
Opossum. 424.g
Eocene. 527.
Oracanthus Milleri, 319.
Orbicula, 187.
Orhis Rotella, 517.
Orbitoides, 104.g
Mantelli. 514. 517.
Orbitolina. 472 g 4s.'!.
Texana, 470. 474.*
Orbulina universa. 104.*
Orehestia, 151.*g
Oregon, Cretaceous in, 403.
Tertiary in. OR). 521.
Oreodon Culliertsoni, 519.
gracilis, 519.*
Orient, 13, 14.
the continent of progress,
585.
Origination of species. 001.
Origin of matter, life, spirit,
and of the spiritual ele¬
ment in the earth's ar¬
rangements. not ex¬
plained by reference t >
heat, water, or attrac¬
tion, 740.
Oriskany sandstone. 200.
Ormoceras. last of, 214.259.
crebriseptum. 221.
tenuifilum, 213,* 215.
Ornitliorynchus, 424.g
Orodus mamillaris. 315.*
Ortliis, 183,*g 191.
biforata, 216.
biloba, 240,* 201.
Ortliis costalis, 210.*
elegantula, 210,* 242, 261,
202.
Flabellulum. 216,* 261.
grandieva, 191.*
hybrida, 201.
Lynx. 213.* 210. 220. 237.
Michelini, var. Burling-
tonensis, 314.*
Occident: Uis, 213,* 220,
245.
parva, 191.
striatula, 182,* 216.
testuilinaria, 213.* 220,
245.
tricenaria. 213*
IJinhraeuiuin, 314, 318.*
varica, 254.*
last of, 374.
Orthisina, 184.g
festinata, 187.
Orthoceras. 156.g 303.
Acicula. 290.*
aculeatum, 349.
implicatum, 201.
juneeum. 213.*
Kiekapooense. 371.
Lamareki. 192.
laqueatum. 192.* 193.
moniliforme. 200. 224. 349.
primigenium, 192.*
recti-anmiiatuni, 210.
tenuiseptum. 210.
uudulatum. 201. *
vertebrale, 213.*
virgatum. 201.
Orthooerata. last of, 405.
Orthnclase, 50.g*
Orthonota carta. 242.
parallela. 221.*
undulata. 284.*
Orthopters. 420.g
Oryeteropus, 423.g
Osborne group. 522.
Oscillations of level, cause of,
71(3, 723.
of water-level, causes of,
57. 7 2o.
through the Palieozoic,
389.'
< Ismeroides Lewesiensis, 4S5.*
Mantelli, 485.
Osmerus, 485.g
Ostracoiils. 154.g
first of. 193.
genera of, 399.
range of, in time, 401.
Ostrea, 399.
acuminata. 464.
liellovacina, 524.
eongesta, 474, 478.
deltoidea, 405.
distorta, 405.
divaricata, 510.
expansa, 405.
Cieorgiana. 518.*
gregaria. 405.
Knorri, 404.
Larva, 474,* 479. 487.
Marshii. 459,*404,405,478.
panda. 510.
selkeformis, 510.*
subovata, 478.
792
INDEX.
Ostrea Vieksburgensis, 518.*
Virginica, 021.
"Vomer, 016.
Otodiw, 477.?
appendiculatus, 477.*
Otozoum Mooilii, 425, 427.*
Ottawa basin, remarks on, 223,
228, 386.
River in existence. 300.
Ottrelite, 77.?
Ourang, 422.? 584.
Outcrop, 105.?
Oris, 020.
Ovula, first of, 484.
Owen, K. (of London), on Dro-
matlierium, 420.
on I lerbivores, 422.?
on Ktereognathus, 462.
Owen, K. (of U. S.), on the po¬
sitions of the outlines of
continents, 39.
Ox family, range of, in time,
572.
Oxford clay, 448.
Oxfordian group, 449.
Oxyrhina, 477.
liastalis, 521.
Oyster, crab found in, 375.
Pachyderms, range of, in time,
572.
Pachynolopus, 529.?
Pachytherium. 423.? 566.
Pacific, observations on, 11.
active volcanoes in, 686.
system of currents in, 42.
change of level in, indi¬
cated by coral islands,
587.
Pacific, island-chains, 30,* 33.
islands,elevations among,
587.
islands, erosion in. 637.
Palseuster niatutina, 212.*
Niagarensis, 148,* 240.
Palivmon, 358.
PaUeecliinus nmltipora, 313*
Paheocrinus striatus, 209.*
Paheocyon. 529.?
Pala-ocvelus rotuloides, 236.*
Paheocystites tenuiradiatus,
191.
Palaolagus, LT. Missouri. 521.
Pahvonisrus. 250.
Kreieslebeni, 375*
lepidurus, 279*
Palfeophis typlueus, 526.
PaUeopliycus irregularis, 178.
tuhularis, 179.
Paheosaur, 340.?
Pala'osaurusCarolinensis,42S.*
Pala'othere, 423.? 526, 527.?
Paheotherium magnum, 527 *
Paheozoic time, 107.
general facts of, 377.
transition from, to Meso-
zoic, 413.
Oleography of, 386.
forces the same as Azoic,
393.
mountains of, 387.
rivers of, 388.
rocks, distribution of, 389.
Palaeozoic rocks, proportion
of, to other rocks, 413.
rocks, thickness of, 377.
section of the Mississippi
basin, 378.
section at Bore Springs,
Va., 404.
section at Pottsville, Pa.,
404.
Palapteryx, 580.
l'alasterina Jamesii, 221.*
Palephemera mediseva, 426.*
Palinurus, shell of, 67.
Pallial impression, 157.?
Pillliohranchs, 179.?
Paloplotherium, 529.?
Palpipes priscus, 461.*
Palm, Tertiary, 513.
Palms, first of, 471.
Tertiary, of England,
524.
Paludina, first of, 453.
carinifera, 465.
Flnviorum, 464.*
Panopa-a oblongata, 518.
Parabatraelius Colei, 358.
Paradoxidos asaphoides, 189.
liennetii. 189.
Ilarlani, 184, 189 *
Tliompsoni, 189.
Vermoutana, 189.
Paris basin. Tertiary of, 522.
Parisian system, 523.
Parma sandstone, 381.
Parophite, 61, 82.?
Pearlstone, 88.?
Peat, 68,? 549, 613.?
Peeopteridse, 338.?
Pecopteris, 338,? 355.
arhorescens, 338,* 342.
Cyatliea, 338, 342.
nervosa, 342.
plumosa. 342.
jiolvmorpha. 342.
Sill'imani. 342.
Stuttgartiensis, 420.*
unita, 338.
velutina, 342.
range of, in time, 494.
Pecten, 399.
tequivalvis, 464.
aviculatus, 349.
circulans, 487.
concentricus, 521.
decennarins. 521.
Islandicus, 552.
Lens, 464.
Lvelli, 516.
Mortoni, 522*
Poulsoni. 518*
5-costatus, 479.
vagans, 464.
Virginianns, 521.
Pegmatite, 76.?
Pelagosaurns, 457.?
lVltura liolopvga. 189.
Pemphix Suenrii, 436,* 438.
Pennsylvania coal-field, map
'of, 323.
faults in, 408.
map of axes of flexures
in. 406.
mineral oil in, 756.
Pennsylvania, section of rocks
of. 379.
Calciferous in, 176.
Carboniferous in, 322,
326, 353.
Cat ski 11 in. 292.
Cauda-Giilli grit in, 269.
Chemung in. 288.
Clinton in, 234.
Hamilton in. 282.
Hudson in. 218.
L. Ilelderherg in, 252.
Medina in, 231.
Millstone grit in, 322.
Niagara in, 238.
Oneida in, 230.
Oriskany in. 266.
Potsdam in, 175.
Subcarboniferous in, 307,
308.
Trenton in, 207.
Triassic in. 416.
Upper Ilelderherg in, 270.
Utiea shale in, 218.
Pentncrinus Asteriscus, 446.*
llriareus, 453, 464.
Caput-Medusai, 161.*
vulgaris, 464.
Pentamerus, 183.?
aratus, 274.
brevirostris, 261.
Conchidium, 242, 202.
elongatus, 274.
galeatus, 252, 254 * 255,
262, 264.
interplicatus. 240,* 261.
Knightii. 264*
oblongus, 235, 237,* 240.
242.
ocoideutalis, 249.
pseudo-galeatus, 252,254,*
255.
Pentamerus limestones. 252.
Pentremites, 162,? 296, 310.
florealis. 312.
Godonii. 312*
pyrifoi mis, 312.*
Peperino. 74.?
Peranitdes. 424.?
Perch. 278.?
Periods and Epochs. 130.?
Perissodactyls, 423.?
Permian period. 369.
Permian and Carboniferous
conformable. 412.
and Carboniferous uncon¬
formable. 412.
in analogous situations
in America and Russia,
373.
Perrey, A., on earthquakes, as
evidence of internal
waves, 684, 730.
Perthes, B. de. on human
relies, 581.
Petherwin group, 294.
Petraia, 392.
Corniculum. 211.*
Petroleum. 756.?
1'etrosilex, 76,? 80.?
Phacops Bufo. 286*
limulurus, 261.
! Phamogams, 106.?
INDEX. 793
Phalangista, 424.?
Phanerostomum senarium,
474.
Pharella Dalcotensis, 478.
Phaseolarctos, 424.?
Phascolomys, 424.?
Phascolotlieri uni Bucklandi,
453, 4(52.*
Phillipsastrea Verneuili, 273.*
Phillipsia, 370.
Cliftonensis, 349.
major, 349.
Missouriensis, 349.
seminifera, 319.*
l'hlogopite, 07.?
Phoca, 529.$
Wyniaui, 521.
Pholadomya 1'idicula, 4G4.
gibbosa, 404.
occidentals, 479.
papyracea, 478.
Plionolite, 87.?
Phosphatic nodules, 66, 67-
Pliragmoceras, 214.?
inuuaturuin, 214.
Phryganea, 420.?
Pliyllograptus Typus, 191.*
Phyllopods, 154.?
a compreliensive type.
597.
first of, 194.
range of, in time, 402.
Physa heterostroplia, 347.
Physeter, 529.?
Physiography. 2.?
Physiographic Chart, 11, 42,
Geology, 7,$ 9.
Phytopsis tubuiosus, 211.
Pbytosaurus, 437.?
Pictet on Dinosaurs, 346.
on Tertiary mammals,
529.
Pictured rocks, 174.
Pierre-k-bot, 545.
Pierre group, 469.
Pillared rocks, 174.
Pinites Brandling!, 337.
Pinna, 399.
peracuta, 349.
Pinnigrades, 422.?
Pinnularia fequalis, 631.*
borealis, 631*
peregrina, 166,* 512.
viridis, 631*
viridula, 631*
Pinus Strobus, 166.*
Pitclistone, 88.?
Pitli of Conifers, 337.
Pitheeus, 529, 584.
Pittsburg coal-bed, 330.
Placodus impressus, 438.
Placoganoids, 279.?
Placoids, 277.?
Plagiaulax, 438.?
Becklesii, 463.
minor, 463.
Plagiostoma gigantea, 454,*
464.
Pliinerkalk, 480.
Planorbis, first of, 453.
Plants, subdivisions of, 165.?
number of living species
of, 575.
Plants, Palaeozoic, number of,
295.
rank of earliest, 396, 596.
and animals, distinctions
of. 747.
changed to graphite, in
gneiss in Connecticut,
409.
terrestrial, in Carboni¬
ferous, 333.
terrestrial, in Catskill
beds, 292.
terrestrial, in Chemung
group, 289.
terrestrial, in Devonian,
302.
terrestrial, in Hamilton
period, 282.
terrestrial, in Ludlow
beds, 264.
terrestrial, in Silurian,
256, 263, 264.
terrestrial, of Tertiary,
512, 525.
Plant-growth of the Carboni¬
ferous, 363.
Plantigrades, 422.?
Plaster of Paris, 04.?
Plastic clay, 522.
Plateaus, 10.? 21.
Platinum, age of, 413.
l'latyceras, 267.?
angulation, 241.*
dumosum, 275.
ventricosum, 255.
Platycrinus Saffordi, 312.*
Platyostoma Niagarensis,241.*
Platyrrhines, 422.?
Plec'trodus, 264.?
Pleistocene of Lyeli, 523.?
See Post-tertiary.
Piesiarctomys, 529.?
Piesiosaurs, 452.?
Plesiosaurus costatus, 437.
dolichodeirus, 452, 456 *
Ilawkinsii, 437.
macroceplialus, 452, 457.*
range of, 487.
Pleuroeystis squnmosus, 212.*
Pleurodonts, 346.?
Pieuroptiorus subcuneatns,
370*
Pleurosigma angulatum, 166.*
Pleurotomaria .• inglica, 464.
Calcifera, 192.
carinata, 319.
expansa, 464.
granulata, 464, 465.
gregaria. 192.
lenticularis, 213,* 224.
litorea, 233.
ornata, 459.
spherulata, 349.*
talmlata, 349.*
Plicated rocks, effects of ero¬
sion of, 681.
Plicating force acting from
the ocean. 410.
force, amount of, 410.
force slow and long con¬
tinued, 411.
Plication of clayey layers, 716.*
of layers caused by slides,
650, 716.
Plications, causes of, 716.
Appalachian, characters
of, 406.
map of axes of, in Penn¬
sylvania. 4U0.*
of Azoic, 140*
Pliocene, 506,? 523.
plants of, in Europe, 525.
See, further, Tertiary.
Pliolophus, 529.?
Pliopithocus, 529.?
Plombieres, zeolites formed
at, 710.
Plumbago, 04.^
Plumbaginous schist, 77.?
Plymouth group, 294.
Poacites, 336.?
Pocillopora, (>18.?
Podozamiteslanceolatus.420.*
Poebrotheriuin, U. Missouri.
519.
Poikilitic group, 372.
Point Levi, rocks of, 175.
Pollicipes, first of, 455.
Polycystines, relations of, 748.
of Barbadoes. Ac., 612.
in Richmond Tertiary ,512.
Polyhalite, 86.?
Polynesian chain of islands,
33*
Polyps, 158.? 103.
first of true, 208.
range of, in time, 460.
Polyptychodon, 482.
Polythalamia. See Riiizopods.
Ponent series. 380.
Porambonites, 18";.?
Porcelain jasper, 79.?
Porcelanite, 79.?
Porcellia, 29(1?
Porcellio, 151 *
Porcupine, 423.?
Porites, 163, 018.?
Porphyrine, 7i).?
Porpliyry, 79.? 87.'?
Portage group', 287.
Porter's Creek group. 509.
Portland dirt-bed, 447, 403.
Oolite. 448.
Portlandian group, 449.
Posidonia, 426.?
Bronnii, 449, 464.
Keuperiana. 438.
minuta, 426,* 436 *
Posidonia schists, 449.
Post-meridian series. 379.
Post-tertiary period, sub¬
divisions of, 535.
geographical progress in.
540, 552. 568.
change in the system of
geological progress in¬
troduced with. 535, 509.
elevated beaches of, 549.
fossils of. in Canada, 552.
in Europe. 558.
lacustrine formations, 548,
life of Australia. 566.
mammals cotemporane-
ous with man, 576, 577.
578, 581.
mammals of Europe, 559.
mammals of North Ame¬
rica, 561.
794
INDEX.
Post-tertiary mammals of S.
America, 503.
terraces, a 17.*
Pot-holes, 041-2
l'otainomva mactriformis,
517.*
Potassium, 53.2
Poteriocrinus longidactylus,
1612.
Missouriensis, 162, 312.*
Potsdam and Oalciferous only
one period, 204.
Period. 171.
American, 172, 178.
European, 177, 193.
green-sand of, 174.
igneous action in, 195.
life of, all marine, 179.
minerals of, 177.
recent genera in, 186.
heils, thickness of, 172,386.
beds overlaid by Carbo¬
niferous, 245.
beds overlying the Azoic
uneonformahly, 172.
fossils in Carboniferous,
Pourtales, on occurrence of
Kliizopods, 612, 664.
on origin of green-sand,
749. '
Pozzuolana, 74.2
Pozzuoli, change of level at,
588 *
Prairies, distribution of, 45.
Prehnite, 62.-J
Pre-meridian series, 379.
Prestwich, on human relies
found with remains of
extinct mammals, 582.
Primal series, 379.
Primordial period, 171.
reality of, in America,
2031
European, 177.
Prince Edward's Island, Car¬
boniferous in, 324.
Edward's Island, Triassic
in, 416.
Prionastrea oblonga, 458.*
Prinnodon in California, 521.
Priscodelphinus, 478.
Proliosciilia, 423.2
Proboscidians, range of, in
time, 572.
Procamelus, in U. Missouri,
522.
Productus, 184,*2 272, 376.
a'quicostatus, 371.
Cora, 348.
costatus, 357.
elegans, 314.
Elemingii, 314.
horriilus, 374.
longispinus, 319,* 357,362.
Martini, 316, 362.
muricatus, 348.
jmnetatns, 314,* 348.
Kogersi, 9,48,* 371.
scabrienius, 357.
semireticulatus, 348, 362,
371.
subalatus, 284.*
sulcatus, 362.
Productus, first of, 303.
last of, 374.
Proetus crassimarginatus,275.
Stokesii, 261.
Progress of life the basis of
subdivisions into ages,
115, 123.
of life, system of, in geo¬
logical time, 592.
of life, law of specializa¬
tion connected with,
599.
Propalaiotherium, 529.
Prosoponiscus problematicus,
375.
Protaxites, 283.
Proteus, 344.2
Proticlinites, 185.*
7-notatus, 189.
Proterosaur, 346,2 376-2
Protcrosaurus Speneri, 375.*
i'rotogine, 81.2
Protomeryx, in U. Missouri.
519'.
Protophytes, 167,2 748.2
Cretaceous, 481.
Pabeozoic, 270.*
Tertiary, 524.
the eariiest life, 596.
Protozoans, 152,2 163,§ 74S.
classification of, 748.
in Tertiary, 514.
the earliest life, 596.
Protozoic schists, 178.
Psammobia lintea, 517.
Psaronius, 355, 374.2
Pseudoliva vetusta, 517.
Pseudomorphism, 704-2
Psilopliyton princeps, 283.
Pteriehthyds, 27!),2* 302.
Pterichthvs Asmusi. 298.
Milleri, 298*
Pterocera Oceani, 465.
Pteroceras, first, of, 453,.
Pterodactyl, 346,2 501.
Pterodactylus crassirostris,
452; 462,* 465.
giganteus, 482.
macronyx, 464.
range of, 487.
Pteronites Chemungensis,
290*
Pterophyllum graminoides,
419*
Jregeri, 434,* 438.
longifolium, 419, 420, 438.
Munsteri, 43,8.
Pteropods, 156,2* 187.*
culmination of, 397.
in green-sand, 217.
range of, in time, 401.
Pterosaurs, 346-2 ^;,2.
range of, in time, 572.
Ptervgotus, 255.2
bilobus, 264.*
Ptilodictya fenestra ta, 210.*
Ptychodus, 47.3.2
Mortoni, 478.*
Pudding-stone, 73.2
Pulaski shales, 750.
Pumice, 88.2
| Pupa, 3,67,2
vetusta, 346. 319.*
I l'urbeck beds, 448.
Purpura, 4: 0.2
Purpuroidea nodulata, 459,
4t ,4.
I^utorius, 529.2
Pycnodonts, 28:',-2
in the Tertiary, the last
of, 520.
Pjcnodus gigas, 43,6, 462.
Pygaster patolliformis, 465.
Pygidium, 18 8.2
l'y gocoplialus Couperi, 3f>8.
Pyramids of Egypt, rock of,
524.
Pyrenean basin, 481.
Pyrenees, elevation of, 533,.
Pyrites, copper, 64-2
iron, 64.2*
iron in coal, 329.
Pyrophyllito. 02,2 ^5-2
Pyroxene, 60.2*
Pyroxenite, 78-2
Quadersandstein, 480.
Quadrumana, 422.2
range of, in time, 572.
Quartz, 55.2*
crystals ill Arkansas. 322
crystals in ( alciferous
sandrock. 175.
Quart zite, 55,2
Quaternary. 8ee Post-tlr-
TIARY.
Quebec group. 175.
Quercus myrtifolia, 514.*
Quito, plateau about, 22.
liadiates, 147-2* 158-2
number of living, 575.
liaocoon. 422.2
hadiolepis speciosus, 427.
ltadiolites, 472.
Austinensis, 474.
Bournoni, 484.*
lamellosus. 474.
Mortoni, 482.
Baft of the Bed Biver. 644.
Bain, causes influencing the
amount of, 46.
Bain-prints, 95.2
Bamsay, on glacial scratches
of Catskill Mts., 753.
Bandanite, 67-2
Banicep.s Lyellii. 350.*
Baucliwacke, 372.
Bays, 277-2
iteceptacuiite limestone. 383.
Beceptaculites Neptuni, 224,
262.
Bed Biver, raft of. 644.
•Beefs. See Coral.
Itegelation, 674-2
itensselaeria, 18i.g 267.
ovoides, 267.*
Bensselaerite. 81.2
a result ofnietamorphism,
711.
lieptilian Age. 414.
contrast of, with the pre¬
sent in life. 499.
footprints. 299, 315,* 424,'"
436,* 438.*
Beptiles, 152.2
number of living, 575
classification of, 343-2
INDEX.
795
Reptiles, culmination of,
range of, in time. 4, ,2,
572.
rank of earliest, 390.
first of, 298,
Carboniferous, 543, 550,
558.
Carboniferous, of Nova
Scotia, 545.
Devonian, 208.
Jurassic, in the Arctic,
758.
Subcarboniferous. 515.
Triassic, 424, 450.
Resins, 69.$
lietepora, i58.$
incepta, 210.*
Retinite, 88.$
lietzia radians, 357.
Yerneuilana, 314.*
Rbabdocarpus, 350.
Rhinoceros, 423.$
Nebrascensis, 515, 519.*
occidentalis, 515.
tichorinus, 501, 577.
Miocene, 529.
in U. Missouri, 522.
Khizopuds, 07, 103.$* 74S.
first of, 210.
Cretaceous, 472, 481.*
Tertiary, 525.
in green-sand, 210,749.
of bottom of ocean, 012,
004, 749.
Rbodea, 555.
Rhode Island, Carboniferous
in, 324, 325.
Rhombifers, 279.$
Rhone, sediment of, 043.
Rhyncholites, 150.$ 455.$
Rhynchonella, 183.$ 399.
bidentata, 201.
bisulcata, 213*
capax, 245.
cuneata, 240,* 201.
increbescens, 215,* 220.
neglecta, 242.
nitida, 201.
nobilis, 255.
Osagensis, 371.
plena. 210*
plicatella, 201.
semiplicata, 255.
spinosa, 404.
sulilepida, 202.
ventricosa, 254,* 255.
range of, in time, 495.
Rhynchonella' common in the
Tertiary, 520.
Rhynchosaur, 501.$
Rhynchosaurus articeps, 450.
Rhynchospira aprinis, 201.
Rill-milrks, 94.$* 005.
Ripidolite, 01.$
Hippie-marks, 94.$* 004.
in Hamilton beds. 282.
in Portage and Chemung
groups, 288.
in Potsdam beds, 170.
in Subcarboniferous, 311.
River-systems, 22.
Rivers, action of, ill making
valleys, 035.
Rivers, erosion by, 05,5.
force of, as related to ve¬
locity, 035.
formation and flow of,052.
increase of, in the Post-
tertiary, 570.
of the Palaeozoic, 588.
small in Devonian. 500.
Rock City, 321.
Rock-making, conditions of,
190.
Rocks, constituents of, 49.$
kinds of, 70.$
structure of. 71 .$
made by Rhizopods, 488,
078.
of coral reefs, 017.
sedimentary, formation
of, 078.
volcanic, 090. 703.
Rocky Mts., Carboniferous in,
324.
Cretaceous in, 409.
Subcarboniferous in, 308.
elevation of, 531.
in Carboniferous Period,
305.
in Paleozoic. 5,'-S.
in the Devonian, 300.
section of, 17.*
Rodents, 42.'!.$
range of, in time, 572.
Rogers, \V. 11. A II. R.. on Ap¬
palachian fau'ts and
flexures, 405, 4u7. 72n.
II. D., on rucks of Penn¬
sylvania, 379.
Rostellaria Americana. 477.*
velatus, 517.
Itotalia Baileyi, 311.
lioueana, 104.*
globulosa, 104.*
lenticulina, 474.
senaria, 474.
Itotli-todt-liegendo, 372.
Kudistes, 472.$
Ruined City, 321.
Ruminants, 422.$
range of, in time, 572.
Rupelian group, 525.
Russia, Carboniferous in, 353.
Cretaceous in, 481.
Devonian in. 295.
Lower Silurian in, 207.
Permian in. 572.
Subcarboniferous in, 318.
Ti •iassic in, 433.
Rutiodon CaroUnensis, 428.*
Salmi, first of. 471.
Tertiary, 513.
Saccliaroidal sandstone, 583.
Saococoma pectinata, 458.*
Satford, on rocks of Tennessee,
384, 509.
Sagenaria Chemungensis, 290.
Sahara, Desert of, 47.
Sahlite, 00.$
St. Helen's group, 522.
St. Lawrence River, in the
Carboniferous, 305.
River, in the Devonian,
300.
St. Lawrence River-svstem,
22.
St. Louis limestone, 307.
St. Peter's sandstone, 175, 205.
St. Pierre group. See pier.no.
Sulamandroids, 344.$
Salilerous epoch. 2 40.
rocks, liow formed, 249,
250.
beds. Triassic, of Europe,
4'»o.
Salina period, 240.
salt-wells, 248.
Salislmria, 357.$
Salix. first of. 471.
Meekii, 471.*
Salmon, 278.$
Salt in England. 45,",.
Salt-works of Eranee, 435.
of (icrniany, 455,.
of Salina. Ac., 2 48.
Salt-group, Onondaga, 240.
Salterella pulchclla, 187.
rugosa, 187.
Sand, 55, 74.$
Sand-bars of coasts, 002.
Sand-drift structure, 93.$
Sand-hills c n sea-shores, 028.
Sand-scratches, 031 .*
Sandrock, calcareous, 73.$
Sandstone, 55, 70, 73.$
origin of, 377.
Sandy Hook, formation o),
004.
Sandwich Islands. See IIa-
waian.
Sao liirsuta, 194.*
Sappliirina Iris, 145,.*
Saratoga Springs, 219.
Sargasso Sea, ('OA.
Sassafras Cretaceum, 471.*
Saurians, 340.$
See Reptiles.
Saurian coprolite, 457.*
Sauroids, 280.$
Saurocophalus laneiformis.
487.
Sauropus primawus. 510,515 *
Saxicava rugosa, 552.
Saxieava sand, 552.
Saxony, disturbances in, 412
Permian in, 572.
Scalaria Groenlaudica. 552.
Sealdisian group. 525.
Sealent series, 379.
Si'aglia, 480.
Scaiites angulatus, 210 *
Scapharca, 522.
Scaphites, 472.$
aajualis, 487.
Conradi, 473, 479*
larvad'ormis, 477,*478,487
Warreni, 487.
Scapolite, 58.$
Scars of Conifers, 53-1,* 350.*
Scelidotheriuni, 425.$ 500.
Schist, varieties of, 77.$ 81.$
Schizodus Rossicus, 371.
Sclilotheimii, 375.
last of, 370.
Schoharie grit, 209.
Schuylkill epoch, 309.
Scolecite, 02.$
TOG
INDEX.
Scolitlius linearis, 180.* 187,
196.
Srolopendrites, 350.
Sconsia Hodgii, 522.
scoria. 690.?
Scoriaceous rocks, "2.?
Scotland,Carboniferous in,353.
'Devonian in, 294.
Scratches, drift, 538.
glacial, 070, 077, 754.
Scratching, hy slides of rock,
050.
Scyinnus in California. 521.
Scyphia reticulata, 407.*
Sea-Anemone. 158.?*
Sea-beaches of Cliamplain
epoch, 547.
absent from New England
at elevations above .500
feet. 042, 503.
Sea-eagles, 278.
Sea-weeds. See Alu.e.
Seal. 422.jj
fossil, 010.
Seam, 92.?
Section, general, of the series
of geological formations,
131*
of coal-measures at Tre-
vorton (lap. I'a.. 404.*
of coal-measures near Nes-
quehoning, I'a.. 493.*
of the coal-measures with
trees. 32.i.*
ideal, of the Appalachians,
490.*
of Chemung beds, 288.*
at • lenesee Falls, 231 .*
of rocks of Illinois, 382.
of rocks of Iowa, 381.
of rocks of Michigan. 3s I.
of rocks of Missouri, 383.
of New York, 171.*
in New York, south from
L. Ontario, 247.*
at Niagara lliver, 232 *
of l'aheo/.oic at Lore
Springs, Ya.. 404.*
of l'aheo/.oic rocks in the
Mississippi basin, 378.*
of rocks of L'ennsylvania,
379.
of Palamzoic at Pottsville,
I'a.. 494.*
of rocks of Tennessee, 384.
Sections of coal-measures, 325.
33.1, 332. 493,* 494.*
of unconformable Carbo¬
niferous. 329.*
of Hamilton beds.281,288.*
Sediment of rivers, 943.J
Sedimentary rocks, 79.(1
strata, modes of format ion
of. 078.
Sedgwick, on Devonian in Eng¬
land, 294.
the term Cambrian, pro¬
posed by, 177.
Selachians. 277.?
range of. in time, 492. 572.
Selaginites. 350.
Selvage, 124.?
Sepia, 451.
Semi-oviparans. 423.?
Semnopithecus, 529.?
Senouian group, 489.
Septaria. 95.?
Serai series. 380.
Sorapis, change of level in the
temple of Jupiter, 588,*
718.
Senilis. 154*
Serpentine, 01.? 82.?
Sertularia. 102.?
aliietina, 190.*
rosacea. 190.*
Shales, few fossils in, 219.
origin of. 377.
Shaly structure, 93.?
Sltaler, on age of Anticosti
rocks, 231, 235.
Sharks, 277.?
,-harks' teeth, abundance of,
in Tertiary. 514.
Shawangnnk grit. 22,9.
Mountains, system of
joints in, 23,9.
Shell-limestone, 85.?
Shell-marl, 85.?
Shells in coal-beds. 300.
Sheppey, fossil fruits of, 524.
Shotover sand. 448.
Miowcr, dust. 029.
Shumard. li. F.. on Texas Cre¬
taceous, 479.
on Texas Tertiary. 509.
Sicily, elevation of, 534.
erosion of the Simeto in,
Pliocene of, 523. [639.
Sieboldia, 344.?
Sierra, 16.?
Sigillaria, 283* 335.?
alveoiaris, 342.
Brochanti, 342.
C'liemungensis, 750.
minutu, 337.
obovata, 336 *
oculata, 330 *
Serlii, 342.
steliata, 342.
tesselata, 342.
vanuxemi, 290*
Sigillariae, or Sigiliarids. 335.?
302,, 395. 418.
Silica, soluble, 488.?
Siliceous group. 398.
materials of rocks from
living species. 00, 07.
Silicon. 51.?
Sillery sandstone. 170.
Sillimanite, 58.?
Silt. 74.?
of rivers, amount of. 043.?
Silurian age. 107.?
subdivisions of, 10.8.
Lower, 171.
Lower, number of species
in, 225, 220.
Lower, thickness of. 380.
Lower, mostly absent
from,U. Missouri, 245.
Upper, 229.
Upper, General Observa¬
tions on. 250.
Upper, features of life of,
258.
Silurian, Upper, number of
species in, 259.
Upper, climate of. 259.
Upper, thickness of, 380.
Upper, absent from Upper
Missouri, 245.
Upper, Arctic American
species of, occurring
elsewhere. 202.
and Devonian united by
the Ludlow beds, 2C4.'
Simeto, erosion of the. 039.
Sinemurian group. 449.
Siphonated Conchifers, 397.
Siphonia loliata, 483.*
Siphonotreta, 184.*?
unguiculata, 217.*
Siredon, 344.?
Siren. 344.?
Sirenia, 423.?
Sivatherium, 529.
Siwalik Hills, Mammals of.
529.
Slate, 77.?
Slatv cleavage or structure.
109.?
cleavage, origin of, 727.
cleavage, production of in
glacier-ice, 074.
Slides. 049.
Mope of Andes, 10.
of llocky Mountains, 10.*
of volcanic mountains,
IS*
Sloth, 423.?
tribe, earliest of, 528.
Snakes, 345.?
first of, 526.
Sneedville limestone, 384.
Snow-line on heights, 071.
Soapstone. 01.? 81.?
Soissonnais beds, 522.
Solemya, 399.
Solen 1'ermianus. 371.
Solenhofen beds, 449.
Solfataras, 099.?
Solidungulates, 423.?
Solitaire, 578 *
Soluble silica. 488.?
Soundings oft' New Jersey and
Long Island, 441.
S. America. Cretaceous in, 481.
Jurassic in, 447.
meiui height of, 15.
South Carolina, Cretaceous in.
409.
Tertiary in, 507, 509.
Spain, Carboniferous in, 352.
Cretaceous in. 481.
Lower Silurian in, 207.
Subcarboniferous in. 318.
Triassic in. 433.
Spalacotherium tricuspidens,
403.
Spatangus. 100.?
Specialization, law of. 599.
examples of law of. in the
earth's history, 739.
Species. See Life, Animals,
Plants.
Specular iron, 05, S3.?
Sphenophyllum. 341, 350.
antiquum, 299.
INDEX.
797
Sphenophyllum emargiua-
tum, 342.
Schlotheimii, 341.*
Sphenopteridaq 338.?
Sphenopteris, 355.
range of, in time, 494.
artemisiaTolia, 342.
glandulosa, 342.
Gravenliorstii, 340.*
latifolia, 342.
Newberryi, 342.
obtusiloba, 342.
polyphylla, 342.
tridactylites, 340.
Spherozoum orientale, 74S.
Spherulites, 88.?
Hoeningshausi, 484.*
Spicule of Sponges, 105, 482,*
748 *
Spiders, 152,? 356.
first of, 451*
range of, in time, 402.
Spinax, 279.?
Blainvillii, 277.*
Spirifer, 182,*? 258, 303.
acuminatus, 274.*
arenosus, 267.
biplicatus, 314*
bisulcatus, 314.*
cameratus, 347.* 371.
Clannyanus, 37 6.
concinnus, 255.
crispus, 243. 261.
cristatus, 374.
cultrijugatus, 274.
disjunctus, 109.*
giganteus, 109*
glaber, 316, 319.*
granuliferus, 284.
gregarius, 274.*
incrassatus, 314.
increbescens, 314.
Kentuckensis, 348.
lineatus, 348, 357.
macropleurus, 252, 254,*
255.
Meusebachanus, 347.*
mucronatus, 284.*
Niagarensis, 240.*
octoplicatus, 314,* 376.
pectiniferus, 371.
perlamellosus, 255.
planoconvexus, 371.
radiatus, 237, 242, 261.
rugosus, 255.
speciosus, 319.
spinosus, 314.
striatus, 181,* 347.
sulcatus, 240,* 261.
umbonatus, 284*
uncinatus, 435.
undulatus, 374.
Urii, 357, 370.
Walcotti, 453.*
range of, in time, 495.
last of, 450.
Spiriferina (= Spirifer) Wal¬
cotti, 464.
Spirigera lamellosa, 318.*
Spiritual element in the
earth's arrangements,
740.
Spirorbis, 367, 399.
Spirilla, 150.?
Sponges, 165.?
spicule of, 165, 482,* 748.*
relations of, 748.
in Chazy, 209.
in Cretaceous, 482.
in Potsdam, ISO.*
in Trenton, 211.
Spougiolitliis appendiculata,
512*
Spore, 165 ?
Springs, thermal, 411.
thermal, in metamorphic
regions. 710.
thermal, in volcanic re¬
gions, 69'. I.
Squalodon, 529.?
Squalodonts, 278.?*
first of, 473.
range of, in time, 572.
Sqnaloids, 278.?
Squalus cornubicus, 67.
Squid, 150.?
Squirrel, 423.?
Stag fiuuilv, range of. in time,
572.'
Stalactite, 85.?
Stalagmite, 85.?
Star-fish, 159.?*
Star-fishes, range of, in time,
400.
Staurotide, 58.?*
Steam, agency of superheated,
in metamorphism, 708.
Steatite. 61,? 81.?
Steffensia, 355.
Steneofihcr, 529.?
Steneosaurus, 346,? 462.
Stenopora, 190.?
Steplianocrinus angulatus,
240*
Stereognathus, 462.? 571.
Sternbergia. 337.?
Stigmaria, 336,? 356.
Anahathra, 342.
ficoides, 337 * 342.
minor, 342.
undulata, 342.
Stilbite. 62.?
Stinkstein, 372.
Stockbridge marble, 391.
Stone period, 583.
Stonesfiehl slate, 44S.
Stones Biver group, 384.
Strata, positions of, 101.
dislocations of, 103.?
order of arrangement of,
112.
Stratification, 90, 91.?
Stratified rocks, 70.?
modes of formation of,
678.
thickness of, 116.
Stratum, 91.?
Strepsirrliines, 422.?
Streptorhynclxus Missourien-
sis, 371.
Umbraculum, 314, 318,*
371.
Strickland on the Dodo, 578.
Stricklandia, 181.?
elongata. 274.
Strike, 105.?
Stringocephalus, 181,? 303.
Stromatopora, 191.?
concentrica, 240,* 242,
26], 262.
Stroniholi. 692.
Strombus, first of, 484.
Stroplialosia, 184.? 376.
excavata. 375.
last of, 376.
Strophomena. 184.?*
alternata, 213* 216. 220,
224.
planumhona, 182.*
punctulifera. 255.
radiata, 254.* 255.
rugo-a, 213 * 240.* 242,
255, 21 d.
range of, in time, 495.
Sturgeon. 278.?
Suhapennine Tertiary, 523.
Suhcai'lioniferous period, 306.
coal in. 307.
Subsidence, causes of, 716.
necessary for the forma¬
tion of a thick series of
strata. 625.
slow during rock-forma¬
tion. 219.
through the Palaeozoic, *
388.
of N. America during the
Drift epoch, evidence
against, 542. 553.
of the Cliamplam epoch,
555.
of the British Channel,
734.
of the Mediterranean in
the Post-tertiary, 734.
of the Pacific indicated
by coral islands, 587.
originating the depres¬
sions of Lake Cham-
plain and the Great
Lakes. 199.
Suctoria, 155.?
Suffolk crag, 523.
Sulphur, 54.?
springs, 248.
Sumter Epoch, 506, 511.
522.
Superga Hill, 523.
Superposition, order of, 113.
Surgent series, 379.
Surireila Craticula, 631.*
Sus. 529.
Swallow on rocks of Missouri,
383.
Swallow & Hawn on Permian,
370.
Swnnton, rocks at. 174.
Sweden, recent change of level
in. 586.
Azoic in, 137.
Cretaceous in, 479.
iron-mines of. 141.
Primordial in. 178.
Trenton in, 207.
Switzerland, Cretaceous in
481.
Tertiary in, 523.
glacier regions of. 668.
great glacier of, 546.
798
INDEX.
Switzerland, formations and
animals of the Post-
tertiary and age of
Man, f>77.
lake-haliitatioiis in, OS2.
Syenite, 78.?
Synclinal, li)5.?
valleys, 105, 722.
Syncoryna, 162.*?
Synedra Ulna, 631.*
Synthetic types, 090,? 200.?
See, further, Comprehen-
sivk.
Syracuse salt-wells, 248.
Syringodi'iidron, 050.
Syringopora llisingeri, 270.
Maclurii, 27:!.*
olisoleta, 220*
Systems of mountain-eleva¬
tions, American, of the
Laurentian, 142, 144,
147, 0S7.
of the Iluronian, 142, 199.
of the Green Mountains,
388, 391.
of the Appalachians, 403.
of the Mesozoic trap and
sandstone, 438.
of the main mass of the
Rocky Mts.. 503, 531.
Systems of mountain-eleva¬
tion, European, of West¬
moreland and the Iluns-
druek, 229.
of the N. of England, 412.
of the Netherlands, or of
llainault, 412.
of the Rhine, 412.
of the Thuringian Forest,
502.
of the Cote d'Or, 502.
of Monte Yiso, 503.
of the Pyrenees and Ju¬
lian Alps, 533.
of the chain of Corsica,533.
of the Western Alps. 533.
of the Eastern or Princi¬
pal Alps, 533.
Systemless animals, 597, 74S.
Taliellaria, 031.*
Tarconic rocks, 176.
Tamiaster spinosa, 212*
Tahitian Islands, map of, 32.*
Talc, 01,? 81.?
Talcose schist, 81.?
Talpa, 529.?
Tancredia Warreniana, 446.*
Tapir, 423.?
Tapirotherium, 529.?
Tapirus, 529.?
Taxinese, 337.?
Teleosaur, 346,? 452, 462.
Toleosaurs, Arctic, 736.
Teleosaurus Tiedmanni, 457.*
Telerpeton Elginense, 298.*
Teliosts, 278.?*
the pure fish type, 599.
first species of, 473.
range of, in time, 572.
in the Cretaceous, 473,
485 *
in the Tertiary, 526.
Tellina calcarea. 552.
Groenlandica, 552.
Temperature, causes deter¬
mining, 45.
of the globe, mean, 45.
of the ocean, 42.
See Climate.
Tennessee, faults in, 407.
rocks of, 384.
Azoic in, 137.
Carboniferous in, 322.
Hamilton in, 282.
Lower Silurian in, 228.
Potsdam in, 175.
Subcarbonilorous in, 308.
Tertiary in, 509.
Trenton in, 206, 207.
Tontaculite limestone, 252.
Tentaculites, 259.
ornatus, 253, 254,* 255.
scalaris, 275.
Teredo tibialis, 479.
Terebratella, 18].?
Terebratula, 181,*? 304, 399.
495.
digona, 464.
diphya, 465.
elongata, 376.
fimbria, 464.
Harlani, 474,* 479.
hastata, 318.*
impressa, 150.*
numismalis, 464.
perovalis, 464.
rimosa, 464.
subtilita, 348.*
varians, 465.
vitrea, 181.*
vulgaris, 435, 438.
range of, in time, 453.
Terebratula- common in the
Tertiary, 526.
Terebratulina, 181,*?
caput serpentinus, 181.*
plicata, 474,* 479.
Terebrirostra, 181.?
Tcrmatosaurus, 438.
Termites, 358,? 420.
Terrace epoch in America,554.
epoch, results of, to Ame¬
rica, 557.
epoch, relations to the
Age of Man, 554, 577.
epoch in Europe, 558.
Terraces of rivers, lakes, and
sea-shores, 547, 554.
in Great Britain, 558.
formation of, 555.*
Terricola, 155.?
Tertiary period, 506.
N. American, 506.
N. American, map of,
530*
foreign, 522.
geographical progress in.
568.
and Post-tertiary, events
of, 568.
and Post-tertiary, con¬
trast in, 568.
Testmlo in U. Missouri, 522.
Atlas, 526.
Culbertsonii, 519.
Testndo liemispherica, 519.
lata, 519.
Oweni, 519.
Tetrabranchiates, 156.?
Tetradecapods, 153.?*
first of, 375.
range of, in time, 402.
Tetradium, 190.?
fibrosum, 220*
Tetragonolepis, 455,* 4f>4.
Text ilaria globulosa, 164,* 474
Missouriensis, 474.
Texas, Carboniferous in, 324.
Cretaceous in, 470.
Potsdam in, 174.
Subearboniferous in, 306.
Tertiary in, 500.
Teudopsis Sclieibleri, 404.
Teutonic period, 583.
Thallogt-ns, 165.?
Thanet sands, 522.
Theca gregarea, 187.*
primordialis, 187.
Thecidea, first of, 453.
Thecidium, 184.?
Thecodonts, 346.?
range of, in time, 572.
first of, 374, 376.
Thecodontosaur, 346.?
Thccodontosaurus, Triassic,
436.
Thenaropus heterodactylus,
351.
Thermal springs, 411, 699, 710.
Thrissops, 279.*
Thuringia, Permian in, 372.
Thylacinus, 421.?
Thylacoleo, 424.?
Thylacotherium Broderipii,
453, 462*
Tiaropsis, 148.*?
Tiburtine, 85.?
Tides and tid;il currents, 652.
Till, 74.?
Time, length of geological,
590.
Time-ratjos, Cenozoic, 568.
Mesozoic, 493.
Palaeozoic, 386.
Titanotherium beds, 515.
Proutii, 515, 519,* 521.
Tivoli travertine beds, 201.
Tourcian group, 449.
Tongrian group, 523.
Topaz, 59.?*
Topographical effects of ero¬
sion, 680.
Tourmaline, 58.?*
Toxaster comjilanatus, 4S7.
elegans, 474, 478.
Toxoceras, 473.?
bituberculatus, 485.*
Tracks. See Footprints.
Trachelomonas levis, 630.*
Trachyte, 87,? S8.?
Trap, S6.?
at Lake .Superior, 1' 5,
199.
distribution and forma¬
tion of, 702.
in Potsdam period, 174.
minerals of Nova Scotia,
430.
INDEX.
799
Trap hi Trias-no of Connecti¬
cut valley, etc., 4oo.
Travertine, 85,?' 201, 574.
Traxites, 358.?
Trees, erect in rocks, 326.*
ill Arctic Post-tertiary
beds, 507.
Tree-ferns, 333.?
Trematis, 184.*-)
Trematodiscus Koninckii,
349/5
Tremolite, 00.?
Trenton epoch, 200.
period, 20a.
period, liornstone of, con¬
taining organisms, 272.
Tretostei nuin punctatum,
40 i.
Triartlirus llecldi, 222.
Triassic period, 414.
American, not marine,
417.
American, coal in, 417.
American, life of, 417.
American, general facts
of, 438.
foreign, 433.
Triceratium obtusion, 512.
Triehomanites, 355.
Triconodon mordax, 403
Trigonia, first of, 450.
aliformis, 487.
Bronnii, 405.
clavellata, 459,* 405.
Conradi, 446.*
costata, 404, 465.
gibbosa, 405.
limbatus, 487.
longus. 487.
muricata, 405.
vulgaris, 438.
Trigonocarpum, 337,? 350.
tricuspidatum, 337.*
Trilobites, characteristics of,
154,? 188.?
a comprehensive tvpe,
597.
extinction of, 303, 357.
range of, in time, 401.
spinous, 297.
Triloculina Josephina, 104.*
Trinidad, mineral oil of, 755.
Trinucleus concentricus, 215*
210, 222.
Trionyx Uakewelli, 404.
Eoeene, 517.
Tritia trivittata, 521.
Trocholites Ainmonius, 214*
221.
Tropidoleptus carinatus, 284.*
Trygon, 279.?
Tubicola, 155.?
Tufa, 70,? 74.?
Tufa-cones, 088,* 095.*
Tully limestone, 281.
Tunicates, 157.?
Tuomey & Holmes, on Plio¬
cene of South Carolina,
511.
Turbellaria, 155.?
Turbinella Wilsoni, 517.
Turbinolia caulifera, 518.
Tui-bo ornatus, 464.
Turbo subplicatus, 404.
Turonian group, 480.
Turrilites, 473.?
lirazoensis, 478.
catenatus, 485.*
Turritella carinata, 517.*
erosa, 552.
Turseodus, 427.
Turtles, 345,? 347.
first of, 438, 402.
range of, in time, 572.
in the American Tertiary,
515.
Tyndall on glaciers, 072, 073,
074, 075.
Types, comprehensive, 203,
395, 500, 595.
culmination of, 399, 400,
. 490, 572, 594, 599.
extinction of, 397,598, 001.
range of different, 400. 571.
572.
Tyson, P. T., on Cycads in
Maryland, 472.
Ulodendron, 350.
Ulster lead and copper mines.
230.
Umbral series, 380.
Uncites, 182.?
Unconformable strata, 111.?
Under-day, 320.?
Undivided types, 39G.§
Ungulates, 422 ?
Ungulite grit, 210.
Unio Diassinus, 440.
prisons, 517.*
Valdensis, 404*
United States, coal areas in,
324.
Geological map of, 133.
Unity in the life of the differ¬
ent ages, 598.
Univalves, 150.?
TJnstratified rocks, 117.?
Uplift, Cincinnati, axis of, 330.
Uplifts, 103.?
See Elevation.
Upper Silurian. See Silu¬
rian.
Urals, elevation of, 733.
Ure-Ox, 580.
Ursus, 529 ?
spelaeus, or Cave Bear,
559 * 577, 582.
Utah, Suticarboniferous in,308.
Utica shale, 217.
Valley, anticlinal, 105, 681.
of erosion, 035.
geoclinal, 722.
nionoelinal, 720, 722.
synclinal, 105, 722.
Valleys, formation of, by
rivers. 035.
formation of, through pli¬
cations, 722.
Vanuxem on plicated clayey
layers, 710.
Varanus Niloticus, 340.
Vegetable kingdom, 105.?
kingdom, relation in ani¬
mal, 747.
Vegetable remains. See
Plants.
Veins, nature and form of,
119,? 120.*
alterations of, 714.
faullings of, 120, 715.
formation of, 711.
ol' Baku Superior region,
origin of, 712.
false, 123.?
Venericardia planicosta, 517.
rotunda, 517.
Venus eancellata, 521.
mercenaria, 521.
Vergent series, 380.
Vermont, Eolian limestone in,
391.
fossil fruits of Brandon,
510, 514.
Potsdam in, 174.
Trenton in, 392.
Upper Helderherg in, 270.
Verneuil, on commencement
of Devonian, 208.
Vertebrate types, range of,
571.
Vertebrates, 151, 152.?
rank of earliest, 396.
first of, 204.
first American, 272.
number of living, 575.
Vespertilio, 527,? 529.
Vespertine series, 380.
Vesuvius, 090.
Vicksburg epoch, 500, 508,517
Vienna, Miocene plants of
525, 534.
Virginia, Carboniferous in,
322.
Cntskill in, 292.
Clinton in. 234.
Cretaceous in, 408.
faults in. 407. 720.
Hamilton in. 281.
Hudson in, 218.
Lower Ilelderberg in, 252.
Medina in, 231.
Millstone grit in, 322.
nionoelinal faults in, 720.
Oneida in, 230.
Oriskany in, 206.
Potsdam in, 175.
Subcarbonil'erous in, 308.
Tertiary in, 507, 510, 511.
thermal springs in, 411.
Triassic in, 410.
Viverra, 529.?
Vivipara l'luviorum, 404.*
Leai, 517.*
retusa, 517.*
Volcanic cones, 087.
Volcanoes, nature and action
of, 085.
source of, 700.
active, in the Pacific,
080.
distribution of, 685.
evidence from, of interna]
heat of globe, 083.
Voluta, first of, 484.
diimosa, 517.
pcfrosa. 517.
Volutilithes petrosa, 517.
INDEX.
«
Yorticella group, 74H.g
Voltzia heteropkvlla, 419.
434 *438.
Wacko, 74.£ 89.g
Walcliia, 373, 374.g
piniformis, 374.*
Waldheimia, 181 .*£
Wales. Carboniferous in, 353.
disturbances in, 412.
gubcarboniferous in, 318.
Triassic in, 433.
Walrus, 422.j)
fossil, alii.
Warren, skeleton of Masto¬
don, 563.
Warsaw limestone, 307.
Washita limestone, 470.
Water, as a dynamical agent.
632.
force of running, 635, 650.
See, further," Rivers.
Oceans, (Ilaciers.
Waters of ocean, specific gra¬
vity of, 650.
subterranean, 648.
Waterlime group, 252.
Wave-marks. i)4.£
Waves, force and action of.
654, 656, 657 * 658.
Waverly sandstone. 288. 308.
Way, ,7. M.. discoveries bv. 750.
Weald clay, 448.
Wealden epoch, 447.
Wear. See Erosion.
Weasel, 422.£
Wells, Artesian, 648*
Wenlock group, 260.
West Indies, trends of islands
in, 37.
Western interior region, 413.
Islands. 38.*
Whale, 423.£
Whales, fossil, 515.
first of, 478.
range of, in time. 572.
Wheatley. on Triassic Rep¬
tiles, 424.
White, M. 0., on Protophytes,
etc., in hornstone, 270,
311.
White Mts., of Devonian age.
409.
Oak Mountain sandstone,
384.
River group, 509, 519.
Whittleseya, 356.
Winchell, A., on Alabama
Cretaceous, 470.
on rocks of Michigan,
380.
Wind River group. 510.
Winnipeg Lake, U. Silurian
fossils at, 242.
Trenton at. 206.
Wisconsin, Calciferous in. 175.
Chazy in, 205.
Clinton in. 234.
lead-mines of 2U7.
Potsdam in, 174.
Trenton in. 206.
Upper Ilelderberg in, 270.
uplifts in, 304.
Wombat, 424.£
Wood, composition of. 300.
decomposition of, 359.
Woodvillc sandstone, 381.
Woodwardites, 355.
Woolwich beds, 522.
Worm-holes in Portage beds,
289.
in Potsdam beds, 185,
197.
Worms, 153.£
range of, in time, 401.
Worthen, A. II.. on rocks of
Illinois, 382.
Xanthidia, 271* 4S1.
Xiphodon, 529.£
Xylobius Sigillarise, 349*
Yoldia limatula, 521*
Yorktown epoch, 506,510,521.
Zamia, 418.*£
Zaplirentis bilateralis. 236.*
gigantea. 270, 273.*
Rafinesquii, 273.*
Zeacrinus elegans, 312*
Zechstein, 372.
Zeolites. 62.£
origin of, 715.
formed in a brick wall at
Ploinbieres, 716.
Zeuglodon cetoides, 515,£517,*
532.
Zones of depth, for oceanic
species, 60S.
Zygobates, in California, 521.
THE END.
electrotyped by l. johnson & co.
philadelphia.
"
;t.FMla.aa