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SOUTH DAKOTA,GEOLOGICAL SURVEY.
EULLETIN NO. I.
A PRELINMINARY REFORT
ON THE
EOLOGY OF SOUTH DAKOTA.
IETY J. E. TOIDID,
STATE GEOLOGIST.
BROWN & SAENGER, starE PRINTERS,
Sioux FALLS, S, DAK,

LETTER OF TRANSMITTAL.
UNIVERSITY OF SOUTH DAKOTA,
VERMILLION, S. D., Dec. 19, 1894.
To the President of the Board of Regents of Education:
DEAR SIR:—I herewith submit Bulletin No. 1 of the Geological and
Natural History Survey of our State, which is a preliminary report on the
Geology of South Dakota.
It is ardently hoped that it may be found of much advantage from both
an educational and an economical standpoint; and that it may be but the
first of a long series, which the State may, from time to time, issue for ac-
quainting her citizens with the remarkable natural resources of our com-
monwealth and the best methods of utilizing them.
Very respectfully,
# J. E. TODD,
State Geologist.
53 : 3
f
CONTENT 5,
LETTER OF TRANSMITTAL - - - - - - - - - -------------------- - - - - - -
CoNTENTS ---------- -------------------------------------
PREFAGE -------------------------------------------------
CHAPTER I. INTRODUCTION ------------------------------.
Aim of this Volume. History of Explorations.
CHAPTER II. Topographic FEATURES.--------------------. --
\ General Features, Black Hills, Table Lands, River Valleys,
Bad Lands. List of Elevations, Towns, I 1. Rivers and
Lakes, 16. Peaks, 17.
CHAPTER III. SKETCH OF THE GEOLOGY OF THE STATE - - - - - - -
Explanations and Definitions, 19. Formations Represented
in the State, 20. Table of Formations, 22. Their General
Attitude, 23.
CHAPTER IV. THE ARCHEAN FORMATIONS - - - - - - - - - - - - - - - - - -
Archean Rocks of the Black Hills, 27. Origin and Age of
the Granite, 32. Formation of Schists and Slates, 33. Sioux
Quartzite, 34. Extent of the Quartzite, 35.
CHAPTER V. THE PALEOzo[C FORMATIONS - - - - - - - - - - - - - - - - - -
Cambrian, 37. Silurian, 42. Devonian, 43. Carboniferous,
44. Detailed Description, 46. Crystal Cave, 47. Wind
Cave, 48. Onyx Cave, 50. Further Notes, 51. Extent of
the Carboniferous, 51. Separation of the Carboniferous and
Red Beds, 52. i
CHAPTER VI. THE MESOZOIC FORMATIONS - - - - - - - - - - - - - - - - - - -
Triassic or Red Beds, 55. Lower Red Beds, 55. Purple
Lirnestone, 56. Upper Red Beds, 58. Cause of Red Color,
59. §urassic, 60. Character of Beds, 61. Fossils of Juras-
sic, 63. Separation of Jurassic and Cretaceous, 65. Creta
ceous, 66. Hayden’s Table, 67. Dakota Formation, 68.
Character of Beds, 69. Exposures about the Black Hills,
70. At East End of State, 75. Lignite in the Dakota, 73.
Data from Artesian Wells, 74. Method of Formation, 82.
Origin of Material, 84. Colorado Group, 85. Extent, 87.
Chalk in the Niobrara, 90. Agricultural Effect of the Fort
Pierre, 90. Alkali, 91. Origin of the Colorado Beds, 92.
Fox Hills Group, 93. Extent, 94. Character, 95, Laramie
or Lignitic, 96. Extent, 96. Character, 96. Equivalents of
the Laramie, 99. Origin of the Laramie, 99.
Page.
iii
vii
19
37
vi
CONTENTS.
CHAPTER
Page.
VII. THE CENozoic ForMATIONS - - - - - - - - - - - - - - - - - - - 101
Tertiary Formations, IoI. White River Beds, Iog. Fossils
x of the Bad Lands, 105. Sand Dikes, IoS. Absence of Al-
kali, Io'ſ. Origin of White River Beds, Io'ſ. Loup Fork
Beds, IoS. Fossils, Io9. Origin, Io9. Extent of Tertiary,
109. Pliocene, Io9. Sºrta/ernary Formations, I 12. Glacial
Deposits or Drifts, 112. Till, Stratified Drift, Moraines, 113.
First Moraine, 115. Second, 13. Third and Fourth, 117.
Osars, I 18. Butte Ridges, I 18. Fluviatile Formations, I 19.
Aqueous Drift, 120. Distinctions Between Western and
Northern Drift, 121. Loess, 122. River Terraces, 122.
Alluvial and Lacustrine Deposits, 124. Eolian or Residual
Loam. Life in the Quaternary, 125.
CHAPTER VIII. ERUPTIVE ROCKS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 127
Diorites, 127. Diabase, Granite, Rhyolite, Trachyte, and
Phonolite, 128. Times of Outflows, 130. Age of the Por-
phyry Eruption, 131.
IX. GEOLOGICAL HISTORY OF SouTH DAKOTA - - - - - - - 133
CHAPTER
CHAPTER X. ECONOMIC GEOLOGY -- - - - - - - - - - - - - - - - - - - - - - - - - 142
Mimcral Ores—Gold, I42; Silver, Copper, Lead and Iron,
t I48; Manganese, Nickel, Tin, 149; Graphite, 150; Mica, 151.
Auilding Stone.-Granite and Quartzite, 151; Sandstone,
253; Limestone, 155; Porphyry, I 56. Cements, Sands,
Clays, Etc., 156. Gypsum, 156; Lime, Portland Cement,
157; Clays, Potter's, Fire and Brick, Sand and Gravel, 158.
§uels—Coal or Lignite, 159; Peat. Waters—Rainfall, Riv-
ers, 160; Springs, 161 ; Lakes, Wells, 162; Artesian Wells,
163; Mineral Waters, Alkali, 164; Natural Gas, 165. Me-
chanical Power—Mill Sites, Artesian Power, 165; Wind
Power, Sun Power. Geology and Soils, 166.
INDEX---------------------------------------------------- 169
Barata --------------------------------------------------- 171
LIET OF ILLUETRATION 5,
PLATE I. View of Sylvan Lake near Custer City--------Frontispiece
PLATE II. Sioux Falls- - - - - - - - - - - - - - - - - - - - - - - - - - - Faces page 34
PLATE III. Artesian well, Woonsocket - - - - - - - - - - - - - - * { 74.
PLATE IV. The Homestake Mine and Mills, Lead City- { % 143
PLATE V. East Sioux Falls Quarry - - - - - - - - - - - - - - - - --------- 152
FIGURE 1. Section Across the Black Hills, according to Newton -- 85
FIGURE 2, Section from the Homestake vein, eastward - - - - - - - - - - 145
Preliminary Geologic Map of South Dakota, at end of
volume. *
PREFACE.
ºr
*
This volume was suggested by calls frequently made on the State Ge-
ologist, for information concerning the State.
The effort has been conscientiously made to present briefly and in pop-
ular form, the present state of our knowledge concerning the geology of
our State. At the same time we have endeavored to put in such matter
as would have value to the student and specialist. How successfully
this has been done is now submitted to the judgment of our citizens.
Numerous technical and novel words have been necessarily used. Most
of them, it is believed, will be found explained or defined at some point
in the book. The Index, with the few additional definitions there added,
it is hoped, will supply the lack.
The insertion of the scientific names of fossils seems about the only
way to express the facts. They may lead some to further study. Most
will be found defined or figured in text books on Geology.
References have been made quite generally to other works, where the
subjects are treated more fully. While many of these are out of print,
copies of them may yet be accessible. Some readers may be glad to
know that the Bulletins of the United States Geological Survey, may be
had at cost by applying to the Director of the Survey at Washington.
Bulletin, No. 106, on the Colorado Formations, figures a large number of
invertebrate fossils found in our State. Price 20 cents,
PRE LIM IN A R Y REPORT
!
OF THE f
GEOLOGY OF SOUTH DAKOTA.
CHAPTER I.
|
INTRODUCTION.
TIII, AIM OF THIS VOLUME,
The survey of the Geology and Natural History of South Dakota
recently inaugurated, contemplates eventually the thorough setting forth
to the public of the natural resources of the State. The moderate ap-
propriation then made, signified, however, to the chief of the survey that
the time had not yet come for a vigorous prosecution of the work. The
limited finances of the new State were doubtless the main reason for this
delay. Little more seemed possible than the collecting and preserving
of data, which are constantly accumulating from the rapid development
of the State. In correspondence with various individuals, who are desirous
to assist in the work as far as possible, an urgent need has been felt for a
brief popular statement of what is already known, as a basis for further
work, as a nucleus for the accumulation of additional data. This is more
reasonable in our State, because more has been done by the general gov-
ernment and private enterprise, before its organization, than in most other
states. The great natural thoroughfare of the Missouri river traverses it,
so that from its earliest occupation by the French until its organization
as a State, it has not only been accessible but of more than usual interest
both from its reported mineral resources and its wonderful fossil remains.
Moreover, the simplicity of its structure has rendered these early and des.
ultory explorations more than usually instructive and helpful. To speak
2 GEOLOGY OF SOUTH DAKOTA,
A
more to qur purpose the present work is published with the hope that it
may be advantageous in respect to the following points:
First. It will render available to our citizens what is already known.
Knowledge, if not readily accessible, is comparatively useless. The
numerous facts concerning the resources of our State, though well known
to the initiated, are so mixed with those of other regions, and in volumes
so difficult to obtain, that they are virtually inaccessible to the people of
our State. Perhaps in no other state are these facts of more practical
and greater economic value. Questions concerning the occurrence of
coal, artesian waters and various minerals are constantly being raised.
These, in most cases, are capable of easy answers from geological facts or
discoveries. But from the ignorance of such data, citizens in some cases
may squander many times the expense of publishing this volume. And
in cases where the desired information has not yet been discovered, where
geology cannot answer with confidence, there may yet be indicated
probabilities which may be very helpful. In short, it is our aim to form a
hand-book of geological information concerning our State which will be
of interest and value, not only to the teacher and scientist, but also to the
capitalist, who may be seeking for investment in mines, quarries or manu-
factures, and also to the farmer and citizen, who wishes to learn reliable
information concerning facts coming to his notice.
Second. It will tend to waken interest and co-operation with the work
of the survey. Not infrequently some curious phenomenon or strange
specimen wakens intense interest. Many questions are raised in an active
mind concerning it, but he knows not where to find answers, nor to gain
light upon the subject. The result is that his interest is crowded out by
more practical and imperative occupations and the germ of scientific
enthusiasm is choked into a dormant or dead state. If however, he could
find answers to his questions or discover the connection between his
isolated fact and other facts, so as to reveal a principle of science, or
gain a vantage ground for further research, either of scientific or economic
value, he might not only taste the pleasure of acquiring knowledge, the
joy of scientific research, but the satisfaction of contributing to the sum
of human knowledge, and thereby to the welfare of mankind. It is hoped
that this little volume may assist in this direction. Again, perhaps some
one more accustomed to approach knowledge from the side of books may
be led to become a practical and helpful observer, at least to appreciate
and encourage observers in their work.
Third. As before suggested, the presentation of this work seems to be
logically the first step, preparatory to collecting and classifying further in-
formation concerning our natural resources. There is not only an ignor-
ance of geology which renders many timid in making inquiries, but also
GEOLOGY OF SOUTH IDAKOTA. 3
much misinformation. Many erroneous ideas are quite prevalent. These
must be corrected before there can be substantial growth of knowledge.
By placing this book in the hands of inquirers along this line, it is hoped
that they may attain that correct view, which shall render further investi-
gation not only possible but pleasant and successful.
In all this it is assumed that citizens of our commonwealth will cheer-
fully co-operate to promote the survey in every way practicable.
HISTORICAL SKETCEI OF EXPLORATIONS.
The first reliable account of the upper Missouri Region, including a
portion of our State, was furnished by Captains Lewis and Clark, sent out
by the general government in 1804-6, to explore the great province of
Louisiana, recently purchased from the French, and to acquaint the In-
dians with the transfer of this region to our own government.
In 1832 Prince Maximillian of Neuwied visited the region of the upper
Missouri and published a magnificiently illustrated report. Little, how-
ever, of geological interest was determined by these explorations, except,
that much of the region was covered with Cretaceous rocks, and the frag-
ments of fine fossils which he brought back aroused great interest among
professional geologists.
The next important expedition was made in 1839 by the distinguished
geographer Jean N. Nicollet. He ascended the Missouri to Fort Pierre,
thence passed northeast into the Minnesota Valley. Mr. Edward Harris,
in 1843, accompanied Audubon to the mouth of the Yellowstone and re-
turned with valuable geological notes for the benefit of the Academy of
Natural Sciences in Philadelphia. An account of the specimens and fossils,
collected by fur-traders and hunters, from the “Bad Lands” of White
River was first published in the American Journal of Science by Dr.
H. A. Prout in 1847. In 1849, Dr. John Evans was sent out by the U. S.
Geologist, Dr. D. D. Owen, to explore the Bad Lands of White River.
His results were published in his Final Report, 1859, pp. 194-206.
The following year Mr. T. A. Culbertson visited the White River and
a portion of the upper Missouri country, in the interest of the Smithsonian
Institution. Dr. Evans again, in 1853, collected important fossils from
the Bad Lands and the White River on his way to Oregon.
In the same year, 1853, the region was visited for the first time by Dr.
F. V. Hayden and Mr. F. B. Meek. These gentlemen were sent out to
collect fossils from the Bad Land region by Prof. James Hall of Albany,
N. Y. The vértebrate fossils were examined by Dr. Leidy, and the inver-
tebrate forms, by Prof. Hall; and Mr. Meek, and furnished the subject of
a memoir, published by the Boston Academy of Science, 1854. In this
was a section prepared by Mr. Meek showing, for the first time, the differ.
4 GEO LOGY OF SOUTH DAKOTA.
ent facts of the Cretaceous in the upper Missouri region. In 1854, Dr.
Hayden, for the most part alone and unaided, traversed it in different di-
rections, often on foot.
In 1855, an expedition was made under the command of Gen. W. S.
Harney for the purpose of laying out roads between military posts. In
1856 these explorations were continued under the command of Lieutenant
G. K. Warren. In this expedition he, was accompanied by Dr. Hayden
as geologist and naturalist. In 1857, Lieutenant Warren obtained the
first reliable information concerning the Black Hills of Dakota. Their
course was past “Raw Hide Butte and down Old Woman's Fork to the
South Cheynenne, thence to Beaver Creek to the east branch by which
they entered the Hills.” From here Lieutenant Warren proceeded north-
ward to Inyan Kara, thence back past Bear Butte, thence southeast to the
Cheyenne, near Sage Creek, thence up the Cheyenne and over to White
River, and thence southeast to the Niobrara. A preliminary report of
this expedition was published by the War Department in 1858.
In 1859 an expedition under the command of Captain W. F. Raynolds,
with Dr. Hayden as geologist, started from Fort Pierre on the Missouri,
for Fort Sarpy on the Yellowstone. This expedition traversed the north-
ern part of the Black Hills; and in the following year, other expeditions
traversed portions of our State between the Missouri and the Black
Hills. The reports of these explorations were not published by the
government until 1868, but Dr. Hayden combined his results to date in a
memoir before the American Philosophièal Society in 1861.
In 1866 Dr. Hayden again visited the Bad Land Region of Niobrara
and the White Rivers, and in the following year the “Geological Survey
of the Territories,” in his charge, was begun under the direction of the
Commissioner of the General Land Office. This was continued several
years. The report for the year 1870 includes most of the results obtained
by Dr. Hayden, so far as concerns South Dakota.
In 1874 Colonel G. A. Custer led an expedition from Fort Abraham
Lincoln to the Black Hills. Prof. N. H. Winchell was geologist of the
expedition and his report was published in 1875. This expedition was
accompanied by gold prospectors, who were successful in finding gold in
several localities.
In 1875 a party was sent out by the Secretary of the Interior, for the
express purpose of making a topographical survey of the Black Hills.
This was placed under the direction of Mr. Walter P. J enney. The per-
sonnel of the expedition, as finally organized, consisted of Walter P.
Jenney, M. E., geologist in charge; Henry Newton, E. M., assistant geolo-
gist; W. T. McGillycuddy, M. D., topographer; Captain Horace B. Tuttle,
A. M., astronomer and naturalist; with a number of miners and laborers.
GEOLOGY, OF SOUTH DAKOTA. • 5
*
}
The summer of 1875 was spent in a rapid and quite careful survey of
the Black Hills, and a Report of the same was published in 1880, which
still remains an important and most complete manual on the natural re-
sources of the Black Hills. In the years subsequent the Hills were visited
by several prominent scientists, including Mr. Israel C. Russell, of the
United States Geological Survey and Prof. Alpheus Hyatt, of Boston, and
Prof. W. A. Crosby, also of Boston, whose short memoirs are valuable con-
tributions to our knowledge of this interesting region.
In 1887 the Legislature of Dakota made a small appropriation to en-
able the School of Mines, at Rapid City, to examine the Geology and
Mineral Resources of the Black Hills; and in 1888 a valuable preliminary
report was prepared and published by Prof. Franklin R. Carpenter, dean
of that school.
Much additional information was collected by the same gentleman,
which the State has not yet found convenient to publish. The Bad Lands
of the White River have been almost constantly visited by distinguished
scientists and collectors from most of the leading educational institutions
of the Eastern States and even from Europe. Important paleontological
works have been written by Professors Marsh, Cope, Scott and others, of
which more will be said on a subsequent page.
Other localities of our State of unusual interest have attracted eminent
geologists from the U. S. Geological Survey and from adjacent States,
who have quite recently published valuable memoirs, to which reference
will be made in their proper connection.
It may enable one to form a more accurate estimate of the peculiar value
of this work, if a brief statement is made of the opportunities for personal
acquaintance with geology of the State have been enjoyed by the writer.
While carrying on investigation for the United States geological survey
during the summers of 1881 to 1889, inclusive, the writer became quite
familiar with the geology of that portion of the State east of the Missouri
river, and during the past season a short trip was taken throughout the
Black Hills and Bad Lands, visiting the following points: Buffalo Gap,
Wind Cave, Rapid City, Hill City, Harney Peak, Deadwood, Lead City,
Elk Creek Canon, and Crystal Cave, Hot Springs, Smithville at the mouth
of Elk Creek, the head waters of Bad River, and then following the
Chamberlain trail from Black T. O. to Rapid City. In this way a general
view was obtained of the older geological formations as displayed in the
Black Hills and the more recent formations with their remarkable fossils,
as found in the Bad Tands.
CHAPTER II.
TOPOGRAPHIC FEATURES.
South Dakota presents greater extremes of altitude and greater variety
of topography than any other state east of the Rocky mountains. Its
lowest point, at Bigstone Lake, is less than a thousand feet above the sea,
(967) while the reputed highest point, Harney Peak, is given by different
authorities as 7,403 and 8,700. These latter elevations, however, are
merely barometric, and it seems not improbable that other points in the
western portion of the Black Hills within our boundary may attain as
high an elevation. These extremes surpass the greatest range of altitude
found in New England or anywhere east of the Mississippi river. As to
variety of surface we have not only very uniform plains, level as a floor,
which are found in the James River Valley and along the Missouri, but
high table lands with gentle undulations, as west of the Missouri and in
smaller areas on the summit of “the Coteaus,” but also narrow canyons
hundreds of feet in depth, presenting on a smaller scale all the wildness
and picturesqueness of the Rocky mountains, as the Elk Creek and Spear-
fish canons in the Black Hills, and the rugged portion and craggy needles
of Harney Peak and vicinity. Not only are there areas in which stones
as large as a pea may be sought for in vain over scores of square miles,
but others where there are almost unbroken surfaces of rock, scarcely sus-
taining vegetation, as in the more barren ranges of the Black Hills, but
ag
barren, as along the sides of the narrow valleys of the Missouri and Chey-
enne, and in limited areas of certain “lake beds,” and others where ero-
sion without those deleterious agencies, goes on so rapidly as to produce
similar barren areas, as in the Bad Lands of White river.
gain areas so saturated with acid and mineral solutions as to be utterly
*s-
The surface may be classified, according to topography, as follows:
First, the Black Hills, which rise as a moutainous, much eroded, dome-
shaped uplift, pushed up above the nearly horizontal beds which cover
the region around.
Second. The Table Lands, which occupy most of the region west of the
Missouri, and smaller isolated areas east of that stream, formerly desig-
nated by the French as the “Plateau du Coteau du Missouri,” and the
“Plateau du Coteau du Prairies,” but more frequently spoken of nowa-
days as the West and East Coteaus.
8 GEOf ,OGY OF SOUTH DAKOTA.
Third. River Valleys, including both the high terraces and the present
flood plains, for example those of the Missouri, Cheyenne, White and
James rivers, of which I shall speak more in detail further on.
Fourth. Limited areas of unique characteristics as the “Bad Land”
areas about the White river and also between the Moreau and Grand
rivers. \
THE BLACK HILLS.
The Black Hills have an area of 5,000 square miles of a rudely
eliptical form with its major axis, approximately, north-northwest. Most of
this area lies within our State. The true limit of the Hills is quite dis-
tinctly marked by a sharp ridge of sandstone, 300 to 600 feet in relative
height, which becomes broader and more plateau-like toward the north
and south ends. This ridge is separated from the higher mass of hills
within by a valley one to three miles in breadth, which is known as the
Red Valley from its brick-red soil, or the “race course,” which name was
given it by the Indians because of its open and smooth character afford-
ing easy and rapid passage around the Hills. The junction of the outer
base of the Hills with the surrounding table lands has an altitude of 3,500
to 4,000 feet. Within this Red Valley one gradually ascends the outer
slope of the Hills and soon enters at an altitude of 4,500 or 5,000 feet the
woody portion of the region. This outer slope varies greatly in width
and is underlaid by older sedimentary rocks, cut in almost every direction
by narrow deep canons. This feature covers nearly the whole of the
western half of the Hills proper, where erosion has been less active on
account of its distance from the main channels of drainage. Usually,
from the broken interior edge of this slope or sedimentary plateau one
descends a bluff or escarpment and enters the central area of slates,
granite and quartzites, which is carved into high ridges and sharp peaks
cut by many narrow and deep valleys and ravines and generally thickly
timbered with the common pine of the Rocky Mountains. Towards the
south, about Harney Peak, the surface is peculiarly rugged and difficult
to traverse. Toward the north, also, about Terry and Custer peaks, a
smaller rugged surface appears; but in the central area between and ex-
tending west of the Harney range is a region which is characterized by
open and level parks much lower than the surrounding peaks and ridges.
TABLE LANDS.
The table lands, which correspond, approximately, to the early
surface of the State before the valleys of the present streams had
been excavated, slopes from an altitude of about 3,500 feet along the west
boundary of the State, eastward to an altitude of about 2,000 feet near
the northeast corner of the State, and 1,450 near the southeast corner.
GEOI,OGY OF SOUTH DAKOTA, 9
{
;
This makes an average slope eastward of about 4 feet per mile along the
northern boundary and less than 6 feet along the southern. The highland
region is everywhere eroded into undulations and there are traces of
higher strata, which occasionally stands out as buttes and ridges. “As
already stated the region west of the Missouri, outside of the Black Hills;
well illustrates this feature. East of the Missouri, it is best seen on the
top of the East Coteau, where it shows a greatest width of 50 miles,
narrowing to a point on the north line of the State in Marshall County,
and slopes gently to the south, the upper course of the Big Sioux drain-
ing its surface. Elsewhere east of the Missouri it has been cut away, ex-
cept in the limited areas of the Bijou Hills, Wessington Hills, Ree Hills,
Bald Mountains, the region about Bowdle, and the table land northwest
of Leola; while narrow traces of this table land are found on the east bank
of the Missouri below.the Bijou Hills and rising into greater prominence
in the Choteau Creek Hills, Turkey Ridge, and more extensively in the
eastern part of Clay and Lincoln counties.
RIVER, WALLEYS.
The river valleys may be briefly sketched as follows: There are two
important valleys crossing our State from north to south, the Missouri
and the James. Another touches upon the northeastern corner of our
State, the Minnesota.
Of these the Minnesota is wide and has an altitude of about 1000 feet
above the sea; the James is from 60 to 70 miles in width, and from 1300
to 1500 feet in altitude at the north line of the State and about 100 feet
lower at the south. It has five important branches, broad and quite even
like itelf. One extends west from Aberdeen at an altitude of 1500 to
1800 feet, another west from Huron, the Ree Valley, of similar height;
and a third southwest from Scotland, from 1400 to 1200; a fourth from
Marion southeast of similar altitude to the last. All these four extend
through to the Missouri river. The fifth, running northeast from Aber-
deen north of the east Coteau, connects this valley with that of the Min-
nesota river. The valleys thus far mentioned have all been smoothed by
the action of glaciers and consequently their contours are much less
sharply defined than those in the western portion of the State.
The Missouri flows in a narrow valley, usually less than three miles in
width, which at the north liné of the State is about 1,550 feet above the
sea or about 250 feet above the James river on the same line. Its tribu-
taries from the west also have narrow valleys, the larger ones the Grand,
Cheyenne and White rivers, have broad, high terraces considerable lower
than the adjacent country. These high terraces are a feature peculiar to
the Missouri and its western tributaries.
1() GEOI,OGY OF SOUTH DAKOTA.
These high terraces are usually classified into two groups. Those along
the Missouri descend more rapidly than the stream and rise higher, 200 to
300 feet above the present stream, while the lower are from 50 to 100
feet below that slope. Along the Cheyenne they are equally well de-
veloped, particularly in the upper portion east of the Black Hills, where
four or five high terraces were traced, ranging at the mouth of Elk Creek
from 200 to 350 feet. These high terraces also show a black soil, along
the streams which radiate from the Black Hills to the two main branches
of the Cheyenne. The upper of these terraces has a gentler slope than the
lower, and the lower decends much less rapidly than the present stream.
For example, the lower terrace along Rapid creek near Rapid City, is less
than 30 feet above the stream, while near the mouth it is nearly 150.
More detailed discussion of these terraces naturally belongs to the treat-
ment of the Pleistocene Formations. These terraces furnish many square
miles of level ground suitable for agriculture.
Along these streams are quite extensive flood plains, affording good
farm land. Oftentimes along the Missouri these are one to two miles
wide, and below its junction with the James river, usually more than twice
that width. These river valleys although largely prairie, are freqently
studded with groves along the smaller streams and with masses of larger
timber in the bends of the main streams. This timber is usually cotton-
wood, ash, elm and soft maple.
IBAD LANDS.
The Bad Land areas have become particularly famous. Their features
particularly impressed early hunters and explorers. A fuller description
of them will be found on a subsequent page. We will here simply say
that they are areas which are called “bad” because of the difficulty of
traversing them. This was caused by the bottomless character of the mud
in spring and the difficulty of obtaining water during much of the sum-
mer, and what is more pertinent to our present theme, the steepness of
the hills and the multiplicity of deep, narrow ravines.
The most notable “bad lands,” or “Mauvaises Terres,” are between the
Cheyenne and White rivers, southeast of the Black Hills. This region
is exceedingly cut up by ravines and is bounded largely with high con-
tinuous clay bluffs. Most of the surface is entirely without vegetation.
They are carved by rapid erosion out of the white clays, marls and sands
of the Tertiary.
Somewhat similar areas of narrow extent are found along the Cheyenne
and Missouri excavated in a similar way out of the lead-colored Cretaceous
clays.
Geology of souTH BAKOTA.
11
ELEVATION OF RAILROAD STATIONS.
All Elevations are from Railroad Levels Eaccept Where Otherwise
Stated. g
Eleva-
LOCATION. t tion.
Aberdeen ------------------------------------------------------------ I,3OO
Alcester-------------------------------------------------------------- I,346
Alba ---------------------------------------------------------------- I,184.
Alexandria ----------------------------------------------------------- I,352
Alpena--------------------------------------------------------------- I,319
Altamont ------------------------------------------------------------ I,834
Altoona-------------------------------------------------------------- I,693
Amherst ------------------------------------------------------------- I,312
Andover ------------------------------------------------------------- I,476
Appleby ------------------------------------------------------------- I,7II
Arlington ------------------------------------------------------------ 1,846
Armour ------------------------------------------------------------- I,5I4.
Artesian-------------------------------------------------------------- I,313
Ashton--------------------------------------------------------------- I,299
Athol ---------------------------------------------------------------- I,296
Aurora-------------------------------------------------------------- I,63O
Bancroft ------------------------------------------------------------- I,562
Barry ---------------------------------------------------------------- I, IO7
Bath ----------------------------------------------------------------- I,3OI
Beardsley ------------------------------------------------------------ I,098
Bennett, Fort (bar:) --------------------------------------------------- I,44O
Benton, Lake--------------------------------------------------------- I,759
Beresford ------------------------------------------------------------ I,5O5
Berwick ------------------------------------------------------------- I,422
Blunt ---------------------------------------------------------------- 1,621
Bonilla -------------------------------------------------------------- I,338
Bowdle--------------------------------------------------------------- I,995
Bradley -------------------------------------------------------------- I,796
Bramhall ------------------------------------------------------------ I,819
Brampton ------------------------------------------------------------ I,289
Brandon-------------------------------------------------------------- I,319
Brandt -------------------------------------------------------------- I,856
Bridgewater ---------------------------------------------------------- I,42O
Bristol --------------------------------------------------------------- I,775
Britton --------------------------------------------------------------- I,352
Broadhead------------------------------------------------------------ I,308
Broadland ----------------------------------------------------------- I,3OO
Brookings ------------------------------------------------------------ 1,636
Bruce --------------------------------------------------------------- I,659
Bryant --------------------------------------------------------------- I,844
Buffalo Gap ---------------------------------------------------------- 3,263
Burbank ------------------------------------------------------------- I, I42
Burkmere ------------------------------------------------------------ I,748
Burton -------------------------------------------------------------- I,33O
Bushnell ------------------------------------------------------------- I,649
Butler---------------------------------------------------------------- 1,82O
Butler Landing, Missouri river, (low water, 1881) ------------------------ I, I26
Butler Landing, Missouri river, (high water, 1881)------------------------ I, I36
Canistota ------------------------------------------------------------ I,455
Canning--------------------------------------------------------------
I,553
12 \
GTEOLOGY OF SOUTH DAKOTA.
\ ELEVATION OF RAILROAD STATIONS Coºrººzed.
W
Groton ---------------
* * * * * * * * * *
LOCATION Eleva-
--~ * \ \ tion.
Canova - ------------------------------------------------------------ I,527
Canton -------------------------------------------------------------- I,248
Carthage ------------------------------------------------------------- I,438
Castlewood ----------------------------------------------------------- 1,685
Cavour--------------------------------------------------------------- I,31 I
º I,22
Centerville ----------------------------------------------------------- } :
Chamberlain, Missouri river, (low water)-------------------------------- I,324.
Chamberlain, Missouri river, (low water, 1882)--------------------------- I,323
Chamberlain---------------------------------------------------------- I,363
Claremont------------------------------------------------------------ 2,302
Clark ---------------------------------------------------------------- I,779
Clear Lake----------------------------------------------------------- I,804
Columbia ------------------------------------------------------------ I,3O4.
Conde-4-------------------------------------------------------------- 1,318
Corona--------------------------------------------------------------- I, I 73
Corson--------------------------------------------------------------- I,362
Crandon ------------------------------------------------------------- I,3O5
Davis Junction (near Elk Point)---------------------------------------- I, II.4.
Peadwood------------------------------------------------------------ 4,545
Pell Rapids----------------------------------------------------------- 1,485
Pelmont ------------------------------------------------------------- I,481
Penster-------------------------------------------------------------- 1,666
Penbigh ------------------------------------------------------------- I,485
Pe Smet ------------------------------------------------------------- 1,726
Poland -------------------------------------------------------------- I,455
Polton -------------------------------------------------------------- I,438
Purham ------------------------------------------------------------- 1,936
Past Prod------------------------------------------------------------ 1,818
*den----------------------------------------------------------------- I,223
Pgan----------------------------------------------------------------- I,525
Plk Point ------------------------------------------------------------ I, I 3 I
Pikton --------------------------------------------------------------- I,75I
Plrod ---------------------------------------------------------------- 1,807
Pstelline ------------------------------------------------------------- I,659
Pthan---------------------------------------------------------------- I,33S
Pureka --------------------------------------------------------------------------- 1,884
Fairmount - 985
Faulkton * * I,595
Ferney * * sºs ºsm ºf I,3OO
Flandreau * * 1,565
Foster --------------------------------------------------------- I,381
Forestburg ---------------------- I,23 I
Forrestville - * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * sº sº ºr sº ms sº *-s ºes s- " - 1,868
Frankfort ------------------------------------------------------------------------. I,296
Freeman --------------------------------- I, 5 II
Fulton------------------------------------------- * * * sº- tº * * * * * * * * * * * * * * * * * * * I,332
Gardner * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * = * * * * * * *= * * * * * * * * I,853
9ary ----------------------------------------------------------------------------- I,484
Gayville -------------------------------------------------------------------------- 1,167
Gettysburg----------------- 2,082
Goodwin ---- * * * * * * *-* * * * * * * * * * * * * * * * * * * * * * = ºr, sº as sºme ers = * =s ºn e- nº e = * * * = ** * * I,996
| & { # *
* GEOLOGY OF SOUTH DAKOTA. , '' . 13
ELEVATIONS OF RAILROAD STATIONS-Continued.
Eleva-
- LOCATION, tion.
Grover -- - * = --> * ~ * ~ *-* wº. – ~ * = - * * * * * * * * *- - - - - * * * * * * * * * * = ** - - - - - - - - - - - -, * * I,742
Harlem ----------------- * * * * * - - - * I,37I
Harney Peak----------------------------------- * sº mº º º = ~ *-* - - - - - -> * * * 7,368
Harrold - * * * I,8or
Hartford --------------------------------- - I,564
Havana -------------------------- - $ * * * * ‘I,294
Hazel ------- r- mºz mºm m amº m ºf emº ºm ºr sº tºs ºs º- * * * * * * * * * * * * * * * * * * * * *-* *-* * * * * * * * * * * * * * * * = * = * * * * * I,765
Hecla.----------------------------------------------------------------I------------- I,3OI
Henry --------------------------------------- * - - - - - - - - - -, * * * I,812
Herman ---------------------- - = * * * * * * * * * * = - - -a sm am amº me I,564
Hermosa -------------------------------------------------------------------------- 3,295
Highmore- — = ---------------- * * * * * * *-* * * * * * * * = ** = ** = = ** * * * * * * *- * * * * * *s I,890
Hillsview ----------------- *— — — — — — — — — — — — — — — — — --— — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — . I,894
Hill City ------------------------------------------------------------------------ 2,322
Hitchcock ------------------------------------------------------------------------ I,339
Holabird ------------------------------------------------------------------------ I,795
Hot Springs.---------------------------------------------------------------------- 3,400
Houghton -------------------------------------------------------------------------- I,3O2
Howard------------------------------------------ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1,564
Huffton-------------- ------------------------------------- - - --------------------- I,3O7
Huron ------------------------------- * = m, ºs ºr - * * * * * * * * * * * * * * * * * ------- I,285
Ipswich as ºa • * * * *-s ºne ºr me • * * * * * * * * * * * * * * * * * * * * * ------------------------------------------- I,53I
Iroquois ------------------------------------------------------------------------- I,4OI
James ----------------------------------------------------------------------------- I,299
James Valley Junction, near Huron -------------------------------------------- I,3I 2
J efferson ------------------------------------------------------------------------- I, II4
Joy ------------------------------------------------------------------------------- I, I38
Kampeska ------------------------------------------------------------------------ 1,766
Kent ----------------------------------------------------------------------------- 1,829
Kidder----------------------------------------------------------------------------- I,295
Kimball ------------------------------------------------------------------------- 1,788
Kranzburg ------- * * = − = ** = * * = * ~ * = <= = ** * * * * ~ - - - - - - - - - - - - - - - - - - - - - - - - -as ve. -- - - - - - - - - - - - I,982
Labolt ---------------------------------------------------------------------------- I,362
Lake Herman----------------- * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 1,646
Lake Preston--------------------------------------------------------------------- I,722
Langford------------------------------------------------------------------------. I,37O
Lebanon --------------------------------------------------------------------------- I,956
Lennox -------------------------------------------------------------------------- I,354
Leola------------------------------------------------------------------------------ I,587
Lesterville------------------------------------------------------------------------- I,385
Loyalton -------------------------------------------------------------------------. I,685
McCook -------------------------------------------------------------------------- I, IO7
Madison -------------------------------------------------------------------------- I,669
Manchester ---------------------------------------------------------------------- I,542
Mansfield---------------------------------------------------- + - - - - - - - - - - - - - - - - - - - - I,3OO
Marion Junction ---------------------------------------------------------------- I,447
Marvin ------- - - * * * *= ** = &m ºms am sm mº am nº ºne ºm * * * * * * * * * * * * * * *:- I,652
Meckling ----------------------------------------- 2^ I, 156
Mellette ------------------------------------------------------------------------- I,3OO
Menno --------------------------------------------------------------------------- I,324
Millard.---------------------------------------------------------------------------- I,640
Miller ---------------------------------------------------------------------------- I,587
14. GEOLOGY OF SOUTH IDAKOTA,
\
ELEVATIONS OF RAHLROAD STATIONS Continued.
LOCATION. \ Eleva-
tion.
Miranda ------ -- * * * - - - -e ºs º-, - - - - * * - - - - - - - - - - - - - * * * - - -s ºr * - - - I,44O
Mitchell, Chicago, Milwaukee and St. Paul Railway------------------------- I,3OI
Mitchell, Chicago, St. Paul, Minneapolis and Omaha Railway .-------------- I, 3 I 2
Montrose ------------------------------------------------------------------------- I,474
Mount Vernon ------------------------------------------------------------------- I,4I3
Naples * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * - - - = - - - as I,091
New Madison --------------------------------------------------------------------- I,646
Newark--------------------------------------------------------------------------- 1,306
Nicholson ------------------------------------------------------------------------- I,309
Nordland -------------. - - - I,846
Northville * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * = * * * * * * * * - w I,299
Ocheeda--------------------------------------------------------------------------- 1,565
Oldham - - - - sº as - - - * * * - - - * * - a- - - - - - - - - * * - - - * * * - - - - - - - - - - - - - - - - - - - - I,92I
Orient------------------------------------------------------- *** - - - - - - - - - - - - - - - - - - - - I,599
Osceola---------------------------------------------------------------------------- I,453
Palisades ------------------------------------------------------------------------- I,457
Palmer --- * * * - - - * * * - - - - - - - - - - - - - - - - - - - - - - - m as - - - - * * - - - - - - - - - - am - - - I,938
Parker ---------------- - - * * * - - - * * * - - - sº se - - - - -> * * - - - -s ºn - - I,348
Parkston -------------------------------------------- I,393
Pennington ----------------------------------------------------------------------- 4,972
Petersburg - * * - - - - - - - - - - - - - - - - - - - - - - - - - - - - 4 - - - - -------------- I,519
Pierre - * am - - - - ame sº - - - - sº ºr - - - - - - - - - - - - - - - -s - - - - * * * - - - * - - - - - - - - - - - -s - - - - - - - - - I,44O
Pierre, Missouri river, (extra low water) ---------------------------------------- I,526
Pierre, Missouri river, (extra high water)--------------------- -$ - - - - - - - - - - - - - - - - I,445
Pierpont-------------------------------------- * - wº. - - - * * - - - as sº * - - - * * * - - -- * * - - - I,5IO
Plana ---------------------------------------------------------------------------- I,3O2
Plankinton----------------------------------------------------------------------. I,528
Preston ---------------------------------------------------------------------------- I,696
Putney--------------------------------------------------------------------------- I,306
Pukwana ------------------------------------------------------------------------- 1,538
Ramona --------------------------------------------------------------------------- I,8or
Ransom ------------------------------------------------------------------------- I,23 I
Rauville -------------------------------------------------------------------------- I,757
Rapid City------------------------------------------------------------------------. 3, 192
Raymond ------------------------------------------------------------------------ I,458
Redfield ---------------------------------------------------- ---------------------- I,295
Redwood ------------------------------------------------------------------------- I,631
Ree Heights---------------------------------------------------------------------. I,73I
Revillo--------------------------------------------------------------------------- I,208
Rockham ------------------------------------------------------------- s = ** - “ - sº *s, * * * I,394
Rousseau------------------------------- - * * - - - - - - - - - - - - - - - * * - - - - - - - - - I,427
Rudolph ------------------------------------------------------------------------ I,3OI
Running Water------------------------------------------------------------------ I,22O
Running Water, Missouri river, (low water, 1881) ---------------------------- I,2O3
Running Water, Missouri river, (extra low water, 1881) ---------------------- I,2O2
St. Lawrence-------------- - * * * - - - - - - - - - - sm * - - - * * * - - - -> * * - - - - - - - - - - - - - - -s sº- - - - I,58O
Salem tº am, ºr º- * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * - * * * * - w am ºn me - - -, * * *-s ºr -w ºr I,52O
Sargent - - - - - - - - - - I,3OI
Scotland -------- * * * * * * * * * * - we - *- - - - - * * * * * * * * = - - - - -es = - - - - - - - - - I,347
Seneca --- -- - - - - - - - - - - - - - - * = - - - - - - * * *-* - - - - - - - - - - - - - - - - - - - - - - - - * * * - - - - - - - - - - - - - , I.9 II
Sheffield ------------------------------------------------------------------------- I, 3 IO
Sherman------------------------------------------------------------------------- I,396
Sioux Falls, Chicago, Milwaukee and St Paul Railroad - - -------------- ---- I,395
GEOLOGY OF SOUTH DAKOTA.
15
f
ELEVATIONS OF-RAILROAD STATIONS-Continued.
Eleva-
I.OCATION. tion.
&
Sioux Falls, Chicago, St. Paul, Minneapolis and Omaha Railroad-----------. 1,397
Sioux Falls, Burlington, Cedar Rapids and Northern Railroad ------------- I,4OO
Sioux Falls, St. Paul, Minneapolis and Manitoba Railroad------------------- I,42O
Sioux Falls Junction---------------------------- - - * * * I,514
Spain------------------------------------ - - - - - - - - ºn was ºs = * * * * * * * * * I,325
Spencer -------------------------------------------------------------- I,387
Springdale ----------------------------------------------------------- I,4OI
Springfield ----------------------------------------------------------- I,234
Sturgis --------------------------------------------------------------| 3,467
Sully, Fort (bar) ------------------------------------------------------ 1,688
Toronto -------------------------------------------------------------- I,994
Tripp ---------------------------------------------------------------- I,556
Troy ---------------------------------------------------------------- 1,885
Tulare --------------------------------------------------------------- I,317
Turton -------------------------------------------------------------- I,323
Twin Brooks --------------------------------------------------------- I,954
Tyler ---------------------------------------------------------------- I,750
Tyndall-------------------------------------------------------------- I,418
Utica ---------------------------------------------------------------- I,387
Verdi ---------------------------------------------------------------- I,771
Vermillion ----------------------------------------------------------- I, I 50
Vermillion, Missouri river, (low water, 1880) ---------------------------- I, I 3 I
Vermillion, Missouri river, (high water, 1881)---------------------------- I, I 44
Vienna--------------------------------------------------------------- I,837
Vilas----------------------------------------------------------------- I,480
Virgil ---------------------------------------------------------------* I,34 I
Virginia------------ ------------------------------------------------- I,2O6
Volga ------------------------------------ * * * * * * * * * * * * * * * - - - - - - - - - - - -, * * 1,636
Volin - * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - I, 181
Wakonda - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - I,396
Ward -,-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - I,754
Warner I,3OI
Watertown------------------------- * * * * *- * * * * * * * * * * * * * - - - - - - - - - - - - - - - - - - - - - 1,738
Watertown Junction ------------------------------------------------------------ I,6O4
Waubay -------------------------------------------------------------------------- I,813
Waverly ------------------------- I,993
Webster__ - - - I,842
Wessington------------------------------------------------------------------------. I,4IO
White-------------------------------------------------------------------------------. 1,778
White Lake - ~ 1,648
Whitewood --------------------------------------------------------------------- 3,640
Willow Lakes -------------------------------------------------------------------- 1,786
Wilmot ------------------------------------- I, 196
Wilson----------------------------------------------------------------------------- 1,366
Wolsey –- I,348
Woonsocket -. - - - - - - - - - - - - - - - - - - - - - - I,308
Worthing ----------------------------------------. * * * * * * * - * * * * * * * * * * * * * * * * * * * *- - - - - - - I,364
Yale - * I,340
Yankton, Chicago and Northwestern Railroad - I,2O6
Yankton, Chicago, Milwaukee and St. Paul Railroad-------------------------. I, I96
Yankton, Missouri river, (low water, 1881) $º * - I, I61
Yankton, Missouri river, (extra low water, 1881)---- I, I 57
Yankton, Missouri liver, (extra high water, 1881)--- I, 198
Yankton, Signal Station-- I,228
Zell- - - * * * * * * * *-* ~ *- - - - - - - - - - - -
1,365
16 GEOLOGY OF SOUTH DAKOTA.
ELEVATIONS OF RIVERS, LAKES, PEAKS, ETC.

} LOCATION. .
#
MIssou RI RIVER—
Bismarck
At north line of South Dakota, estimated, low water,
Pierre
Chamberlain
* * * - * * * * * * * * * * * * * * * * * * * * = ºr
*-* - - - - - -
* - - - * * * - * * * * * * * * * * * * * * * * * * * * * *- - - -
- - - * * * - - - * *
- * * * * - - * * * * - * * * * * - * * * * * * * * * * * * * *s
Bijou Hills
f Running Water
Yankton
Sioux City
CHEY ENNE RIVER—
South branch, lat. 43° 30' N and about 103° W lon
North branch, Belle Fourche, 44 ° 40' N lat., and about IO3°
W long.
Month, estimated
JAMES RIVER—
Columbia, estimated
East of Plana, railroad crossing
East of Aberdeen, {-
East of Redfield,
East of Huron,
East of Forestburg
East of Mitchell
East of Scotland
East of Yankton
BIG SIOUx RIVER—
- * * * * * *
* * * * * = ** - * * * * - was ºn at- tº wº. - - - * * - * * * * * * *
- - -s tº a.º. - - - - - - - - - - - - - * * - - - -
- *- -* * *- * = - - - - * * * - - * * * * * * * * * * v- * * * * * * * * *
* * * * * * * = s.
- - - - - - - - * * * - - - sº sº. - - -, * mas
- - me ºn m - - - *** - - - - * * *-
• * = * * - ºr * * * - - * * * * * * * * * *- - - see - * wº. -- * *
* sº * v- - - - - - - - - - - - - - * * * - - - as “ - - - * *
- * = ** - - -- * * - - - - - - - - - - - - - - * * * - - - - -
* *m; mºs, - - - - - - - - - - - - - - - * * * - * * * * - - - - -
- sm - - - - - - - - - - -- * - - - - - - - - - * * - - - * es
* ame * * - - - - - - - - sº sº wº. - * * * *- - - - mºs ºº - - - sºme *
East of Waubay, railroad crossing
Near Watertown,
Near Volga
Near Egan
Near Dell Rapids
Near Sioux Falls
Near Sioux Falls
Near Brandon
Near Canton
Near Hawarden
Near Akron
Near Riverside Park
VERMILLION RIVER—
Near Winfred, east branch, railroad crossing
Near Montrose, - -
Near Howard, west branch,
Near Parker, g
East of Parker, main stream,
Near Centerville, main stream
Near Vermillion
* -
* * * * * * * * * * * * * * * * * * * * *-* = * * * * * * *.
* - - ºr ºm me
a- - - - -- * *- - - - *** - - - - - - - - - - - - - - - - - -
west of town
above the falls
below the falls-------------
* - - - - -s - - - - * *
* - - - - - - - - - -- *** - - - - - - - - - * - - - - - -
* - - - - - - - - - * * * - - - - - - - - - - - - - - - - *
- * * * *- - - - - - - - - - - - - - - ºne eme
- - - * * * - - - sm ms - - - - - -
- - - * * * - - * * * * - - - - as
- - - * * - - - - sº ºr - - - - sº m
* - - * * * - - - - - - - - - sº ºf
Andes, Lake------------------------------------------------------------
Big Stone Lake
Blue Lake, near Waubay
Herman, Lake
Kampeska, Lake
Madison, Lake-----------------------------------------------
Preston, Lake
Red Lake-------------------------------------------------------------
º- - - - - - - - - - - - -
- -- * * * * * * * * * * - - sºme me = - - - = my
* * * * * * * * * * * * * * * * * * * * * = = * * * * = - - - eas - - - - -
as ame - * * * * * * *s º – sº wº wºº tº - * * * * * * * * * * * * * * * * * - - am s - * * * - - sº ms
-
• * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * = * * * = see - -
.* = * * * * * * * * * * * * * * * * * = ** - -
- * - - - sº * - - * * * - -
- - - - * * *- - - - sº
Low.
- - ºr * * - - -ºº:
* * * = * * * *
- - * * * *- - -
- - - tº as - - -
- - - mºs º – - -
- - - tº - - - -
- - - * * - - -
* - * * * - - -
- - - sº - - - -º
- - - - - - - -
- - * * * - - -
- - -º º ºn - - -
- - - * * - - -
- - - -sa - - - -
* - * * * - - -
- - - -- * - - - -
* * * * * * * *
} &#
*
f
GEOLOGY OF SOUTH DAKOTA. 17
ELEVATIONS OF RIVERS, PEAKS, ETC.–Continued.
|
LOCATION. Low. || High.
Sand Lake or Tcanchicahah, estimated, ------------------------ I,290 --------
Traverse, Lake----------------------------------------------- 97I 976
Bear Butte, Meade county -------------------- ---------------- 4,573 |--------
Bijou Hills, Brule county, (bar)-------------------------------- I,95O --------
Black Horse Butte, Schnasse County --------------------------- 2,680 --------
Black Butte, Lawrence county, (bar)--------------------------- 5,950 --------
Crook's Tower, Lawrence county ----------------------------- 7,140 --------
Crow Peak, Lawrence county -------------------------------- 5,772 --------
Custer Peak, Lawrence county, (bar.) --------------------------| 6,812 --------
Dodge Peak, Pennington County ------------------------------ 6,989 --------
Flint Rock Buttes, Rhinehart county ---------- ---------------- 2,665 |--------
Harney Peak, Pennington county, (bar.) ----------------------- 7,403 ||--------
Hills about Bowdle, Edmunds County ---------------------- OVer 2,000 |- - - - - - - -
Hills east of Gettysburg, Potter county ------------------------ 2,OOO - - - - - - - -
Hills northwest of Leola, McPherson county --------------- OVer 2,OOO |- - - - - - - -
Medicine Butte, Presho county, (bar) --------------------------| 2,000 --------
Piedmont Butte, Meade county ------------------------------- 4,173 |--------
Plateau du Coteau des Prairies -------------------------------- I,7OO 2,000
Plateau south of Crook's Tower---------------------------- OVer 7, IOO |- - - - - - - -
Rabbit Butte, Choteau county --------------------------------- 3,OOO |--------
Ree Hills, Hand county, (bar.) ----------------------------over 2,000 |--------
Terry Peak, Lawrence county -------- ------------------------ 7,070 --------
Thunder Butte, Schnasse county ----------------------------- 2,830 --------
Turtle Point, Wessington Hills, (bar.) ------------------------- I595O |--------

CHAPTER III.
A SKETCH OF THE GEOLOGY OF THE STATE.
ExPLANATIONS AND DEFINITIONS.
For the benefit of those who are unfamiliar with the fundamental facts
and principles of geology, we will give briefly a few explanations and
definitions. , f
At nearly all points upon the earth's surface the rocks exposed or dis-
covered by mines or borings, are found to be composed of layers of vary-
ing thickness. These are arranged like blankets, one above another, each
one extending over many square miles. A single one is called a stratum,
and the rock composed of them is said to be stratified. Strata (plural)
lie nearly horizontal over nearly the whole of our State. When tilted,
as about the Black Hills, the angle made with the horizontal plane,
and the direction toward which the rock descends, together, constitute the
dip.
Stratified rocks, with very rare exceptions, have been formed under
water, as sediment, somewhat as strata of sand and mud are now forming
in the Gulf of Mexico, from the material carried down by the Mississippi
and by waves and currents from the shores of the gulf. Almost all the
rocks of our State have been formed in the ocean, as is shown by their
containing the shells and bones of marine animals. These remains of
animal life, and plant life also, are called fossils. As new and higher
forms of life have been introduced in successive ages, while strata were
forming, one after and one above another, it follows that the stratified, or
sedimentary rocks, constitute nature's record of the history of life from
“monad to man.” Also, contrariwise, the fossils in a rock enable one to
tell often with great confidence, from what part of the record even a frag-
ment has been taken, just as a picture on a leaf from a book, with which
one is familiar, may tell just where it belongs. Some strata have been
formed in lakes, and still others in streams. By careful study one may
tell the direction in which the streams flowed, and many other curious and
valuable facts.
Strata, though all soft at first, have sometimes become consolidated by
pressure and the action of molecular forces, into rock of great or less
hardness. Such are usually broken by vertical seams (called joints) into
blocks,
20 GEOLOGY OF SOUTH DAKOTA.
In some localities, like the Black Hills, strata are profoundly, folded
and fissured. Sometimes the strata on one side of the fissure have slipped
down so as to lose their former position with reference to those on the
other side. Such a displacement is called a fault. Sometimes fissures
and other openings become filled with various minerals derived from the
adjacent rock by the dissolving action of water. Such form the veins,
“ leads” and pockets of the miner.
Sometimes rocks of the earth's crust become plastic or melted and flow
out through fissures. In the process of cooling they become what are
called igneous rocks. When igneous rocks are cooled in a fissure they
constitute a d ke. If they push up the overlying strata and form a lent-
icular, or dome-like, mass, it is called a laccolife.
Igneous rocks are compound of crystals of different minerals either
wholly or with an imbedding paste of glassy or porcelain-like rock. The
latter are called Trachyte, Rhyolite, Phonolite, Porphyry, &c., according
to their composition or coarseness of grains.
Rocks wholly crystaline, breaking with equal ease in any direction, are
called massive rocks, and are named Granite, Syenite, Diorite, Diabase,
Greisen, &c., according to the kind of minerals composing them. If they
break in slabs they are called Gneiss or Gneissid, if in uneven plates,
Schists, if in even Slates.
The strata found in the earth's crust are classified by grouping them
first into Great System, which are divided into Systems; then system ares
divided into Groups, and groups into Stages. These divisions are based
upon differences in the life forms found in them, the characters of the
rocks, and other features or relations which make a distinction convenient.
Each of these groups of strata corresponds to a division of time, in which
it was formed. A great system was formed in an Eon, a system in an
Age, a group in a Period, and a stage in an Epoch. Usually a group of
of strata and its corresponding time division are called by the same name.
The names of formations and time divisions are largely geographical, de-
rived from some region or locality where they were first studied or typ-
ically exposed. Some are named from some phase of life or character-
istic of deposits belonging to them. The reasons for the different names
will generally be found in connection with their detailed treatment in
subsequent chapters. Most important names commonly used in this coun-
try will be found in the table in the next section.
FORMATION'S REPRESENTED IN THE STATE.
gº
South Dakota is also remarkable for having a greater variety of geo-
logical formations than any other state east of the Rocky Mountains. Of
the different ages represented, we mention the Archean, Cambrian, Silu-
GEOLOGY OF SOUTH DAKOTA. 21
rian, Carboniferous, Triassic, j urassic, Cretaceous, Miocene, Pliocene and
Pleistocene. The Archean is represented by two or three remarkably dif-
ferent formations, the correlation of which is not yet satisfactorily deter-
mined, but following Newton and Carpenter we may call them the earlier
Archean schists, and the later Archean slates of the Black Hills; while the
eastern end of the State presents a red quartzite, known as the Sioux
Quartzite, or Sioux Falls granite, which has been classified most com-
monly as Huronian, and about Big Stone Lake, an area of coarse granite,
probably Laurentian.
The Cambrian is represented only in the Black Hills and by the Pots-
dam sandstone, which manifests its common characteristics and has a
thickness in places of 250 feet.
Above it there has been found near Deadwood, since the publication of
Prof. Carpenter's work, a formation from 20 to 30 feet in thickness,
which presents the features of the Trenton limestone and represents the
Silurian.
So far as has yet been discovered the Devonian is absent, unless it is
represented by 25 or 30 feet of greenish shales, which are exposed near
F)eadwood, between the Trentom limestone and the base of the Carbonif-
€I’O UlS.
The Carboniferous age is represented by a variety of formations, ag-
gregating in thickness over 600 feet. All these Paleozoic formations are
limited to the Black Hills. *.
The Triassic age is represented by 340 feet of a bright red clay bear-
ing irregular beds of gypsum and a very uniformly developed stratum of
purple limestone 40 feet in thickness, the whole entirely barren of fossils.
The Jurassic is represented by about 200 feet of sandstone and marls
of various colors.
The Cretaceous is represented by several well marked formations widely
developed, covering perhaps four-fifths of the area of the State. These
have more frequently been classified as the Dakota formation, 200 to 400
feet in thickness; the Colorado, including the broad area of Fort Benton,
Niobrara and Fort Pierre, clays, marls and limestones, aggregating in places
a thickness of 1,500 feet. And the third member of the Cretaceous has
been called by Dr. Hayden the Fox Hills, which shows a thickness of 100
to 150 feet, and a fourth is the Laramie or Lignitic having a thickness of
1000 to 2000 feet. The last two formations are found only in the north-
western quarter of the State.
The Eocene seems not to be represented in the State, unless possibly
some of the yellowish clays in the Bad. Lands, which are without fossils
to determine their age, may belong to this age.
The Miocene is widely developed in the southern part of the State.
22 GEOLOGY OF SOUTH DAKOTA.
Under this head we include, following the later classification of Prof.
Cope, the White river and Loup fork formations, which are not easily dis-
tinguished lithologically, and have aggregated a thickness in this region
of more than 300 feet, having more or less gray and flesh colored clays,
stratified with conglomerates and marls.
The Pliocene is of somewhat doubtful occurrence.
served along the Big Sioux seem referable to this age.
The Pleistocene or Quaternary formations are particularly prominent,
and are represented, not only by a fine development of glacial deposits,
loams and other features in the eastern half of the State, but also, about
the Black Hills and over very much of the surface of the plains, by aqueous
drift. The present topographic features, also, are mostly to be referred to
this age.
The subjoined synopsis represents the Geological column represented
in the State.
Certain beds ob-
A TABLE OF SOUTH DAKOTA GEOILOGICAL FORMATIONS.
(ARRANGED STRATIGRAPHICALLY.)
Great
Systems. Systems. Periods and Stages.
( Quaternary,
| Alluvium and Prairie Loam, 5—IO
| Loess, 5—IOO
| Drift, Glacial and Aqueous, IO-I 50
Cenozoic-- { Equus beds, (?) 5–3O
| Tertiary,
| Pliocene, Loup Fork beds, 25-75
| Miocene, White River beds, 250–4CO
U Eocene, Absent,
| Cretaceous,
Later, Laramie, or Lignitic, I,000–2,000
Fox Hills, IOO–15O
Colorado, Ft. Pierre, 350–700
. . Niobrara, O–2OO
Mesozoic- -: Ft. Benton, :
Dakota, 2OO–5OO
Earlier, Absent,
Jurassic, { 2OO–35O
UTriassic, 3OO–400
ſCarboniferous, 570–785
Devonian, Absent (?) O–55
Silurian,
Paleozoic - { Upper, Absent (?)
| Lower, Trenton, 225–2O
| Canadian, absent (?)
UCambrian, Potsdam, Acadian, absent 2 250–300
ſ Keweenian, Absent,
| Huronian, Upper, Sioux Quartzite, I,OOO–3,OOO
Archean - - Lower, Schists and slates, IO,OOO 2–IOO,OOO P
ULaurentian, Absent (?)
f
; GEOLOGY OF SOUTH DAKOTA. , 23
y
THE GENERAL ATTITUDE, OF THE GEOLOGICAL FORMATIONS.
f
The opposite ends of the State contain each of them a distinct center
of geological growth. One is the Black Hills, the other, the Archean
area about Sioux Falls. The former is an irregular dome shaped uplift
with its longer axis north-northwest; the latter a low ridge with its axis
west-southwest, gradually sinking below the later formations in that direc-
tion, with its north side more abrupt than its southern.
Around these two nuclei the older rocks of later formations have been
arranged, somewhat as blankets might lie upon a saddle. The Cretaceous
and Tertiary formations cover nearly the whole State outside of the Black
Hills. * f
It follows from this general statement that, while the general slope of
the country is toward the east, the dip of the rocks radiate from those tWO
centers, and is slightly southward in the south central portion of the State,
and northwestward in the northern portion. }
chAPTER IV.
THE ARCHEAN ‘FORMATIONS.
Archean rocks, as the name suggests, (arche, beginning), are those
rocks which underlie the others in the structure of the earth's erust. They
are, theoretically, of world-wide extent; though exposed in detached areas,
commonly in the center of mountain systems and plateaus. They are
rocks in which no trace of living forms have been found. They are more-
over of a crystalline character. By crystalline rocks we mean such as are
formed of angular grains, interlocking as though crystallized from a
fluid state. There are all gradations of rocks found in nature, from
those which are wholly crystalline to those where there is not a trace of
crystallization, the whole mass consisting largely of rounded grains and
fragments of various shapes and sizes. The former would be illustrated
by rocks commonly known as granite, which may be compared to cast
iron in structure, except the grains are often times unlike in the same
rock, some being black, others white, red or green of various shades and
lustres. Some show a tendency to cleave with smooth and even surfaces
sometimes into thin leaves, others show no trace of such cleavage. They
break irregularly like glass. Some are soft, others very hard. Archean
rocks are almost wholly crystalline, although some reveal traces of worn
grains or fragments.
The Archean rocks include all the oldest rocks of the earth’s crust.
Some of them were evidently at one time laid down in water in a stratified
condition, Others show no signs of bedding. The latter occur in great
masses, divided only by cracks running in different directions. Rocks of
this character are usually found underlying those of a clearly stratified
character. - -
Concerning the origin of these massive crystalline rocks the following
theories are held by different prominent geologists:
First. The oldest theory is, that they are portions of the ori
of the earth when it first cooled from a molten condition.
ginal Crust
Second. That they have once been composed of stratified material de-
posited like the rocks above them, and that afterwards having been deeply
buried under the overlying formations, and they have been completely
&
26 GEOLOGY OF SOUTH DAKOTA. g #
*= #
changed by pressure and heat from the earth's interior from a fragmental
condition to a crystalline. Every trace of stratification, and even of the
fragmental character of individual grains, has been completely obliterated.
Third. It is supposed that the underlying crystalline rocks have never
been in the form of stratified rocks, nor that they were solidified previous
to the deposition or formation of the stratified rocks overlying them, but
that they are a portion of a molten or plastic interior of the earth, which
has risen in the center of folds, or into fissures formed in the stratified
rocks above them, and which have become hardened as they have been
brought nearer to the surface and cooled. This view considers them
really younger than the stratified rocks, and may explain how rocks of
this character may be found, not only under the stratified rocks but fol-
lowing great cracks and other cavities in the stratified rocks themselves.
This last view is the most prevalent at the present time.
Of the Archean rocks, which are admitted to have been at sometime
stratified, there are three well marked divisions recognized. One which
has been called the Laurentian, named from its typical locality in the
highlands, north of the Great Lakes and the river St. Lawrence. These
rocks are granites, mica-schists, hornblendic rocks of similar structure,
and limestones passing into marbles. The second division has been called
the Huronian, because of its occurring in the vicinity of Lake Huron.
These consist largely of schists or rocks which tend to split into thin ir-
regular layers; slates, which break more evenly, and quartzites, which
may be defined as intensly hard crystalline sandstone. The third divis-
ion has been found in several localities and is called Keweenian or Kew-
eenawan, after Keweenaw Point on the south shore of Lake Superior,
where it is typically developed. It consists of alternate layers of quart-
zite and volcanic rocks with deposits of copper.
Of these different formations we have in our State only those apparently
corresponding to the second division, or Huronian. The coarse granite
which forms Harney Peak and covers much of the vicinity, was considered
by Dr. Hayden as corresponding to the Laurentian formation, and in this
respect he seems to be followed by Crosby and Carpenter. At least,
these others consider that the granite was deposited like the adjacent
schists in fragmental condition, and afterwards, was most completely
metamorphosed, or changed to a crystalline condition. That, however,
this was eruptive and introduced later than the surrounding rocks seems
evident from a careful study of its relation to them. Not only does it
occur in vast lenticular masses, with their axes corresponding to the planes
of the bedding of the schistose rocks, but also huge fissures cutting ačross
the planes are filled with this same material. A fine example of this
may be found a few miles west of Keystone, where the planes of schist-
GEOLOGY OF SOUTH DAKOTA. 27
{
ose character coincide in dip on opposite sides of the dike, on the one side
dipping sharply toward the dike, on the opposite side as sharply away
from it. In this case it seems clear that the granite could not have been
formed from a metamorphosed stratum deposited between the surround-
ing rocks. The failure of the theory at this point makes it doubtful
in all other cases. Moreover an examination of the detached layers of
schists which are found within the granite mass near the top of Harney
Peak, referred to by Prof. Carpenter show signs of having bean floated
to their present position by the molten granite, rather than of having been
interstratified with it when in a fragmental condition. We therefore
conclude, as before stated, that the granites of the Black Hills are not
Laurentian, but eruptive rocks, formed later than the schists, and in this
we agree with the majority of those who have studied the matter.
THE ARCHIEAN Rocks IN THE BLACK HIII.S.
These differ markedly in color and general structure from those found
in the eastern part of our State. As may be seen on the geological map,
they occupy a central, or nucleal, area, and their exposure is somewhat to
the east of the center of uplift. The extent of country occupied by
them is about sixty miles long, north and south, and twenty-five miles in
its greatest width east and west, with an area of about 850 square miles.
The area underlaid by the Archean schists and slates is particularly
mountainous and rough, especially where it is mingled with granite out-
flows. Where these quartzite deposits are absent, erosion has removed
the schists and slates which are softer, so as to form park-like valleys, to
which we have already aluded. As Newton says:
“Viewed from a height, like Harney Peak, the area has a billowy ap-
pearance and a succession of ridges and peaks, with now and then a stretch
or spot of open park. At first it reveals no system of structure, save that
is cut from west to east by the draining streams, which have eroded deep
and usually narrow valleys or canyons. Though the strike of the rocks
is toward the north or northwest, at first appearance, they show no feature
in the topography due to this fact, but a closer and more detail study reveals
the presence of a continuous ridge, or series of ridges extending on the
east side of the area from the southeast to the northwest, and, on a more
minute inspection of the geology along the streams, these ridges are seen to
have been divided by the presence of apparently hard strata, quartzites, etc.,
through which the several draining streams have cut their way in intricate
and deep canyons. On the western side of the area, a similar belt of resistant
rock is observed, through which many of the streams have cut narrow gorges.
Between these ridges the country, except in the region of the Harney
Peak granite, is less rugged, and not infrequently the banks of the streams
widen out into valleys, broad and gently sloping.” (Geology of the
Black Hills of Dakota, (Newton), page 49.) He adds: “The metamorphic
rocks of the Black Hills are separable into two distinct groups, whose
$
28 GEOILOGY OF SOUTH DAKOTA.
\.
lithological characters are marked and persistent. Their stratigraphy
was carefully studied in the hope that it would be possible to definitely
determine the historical relation between them, but the result was not
satisfactory. A great difference in the character of the rocks are sufficient
to warrant their separation into a western series or group of schists and an
eastern series or group of slates. The line of separation between them
can be only imperfectly indicated. Its trend, so far as can be ascertained,
is little west of north. Starting just east of the granite range of Harney
Peak, it curves westward, about the north end of the range, and then it
leans toward the north-northwest, passing near the forks of Spring Creek,
(the present site of Hill City) crossing Castle Creek in the west canyon
and disappears beneath the Paleozoic rocks in the vicinity of Custer Peak.
At the north of the Peak it reappears with a northerly course.” “A dis-
tinct discordance of dip between the rocks representing the characters of
these two groups was seen by Mr. Jenney in the west canyon of Castle
Creek, but in the absence of corroborative observations the fact of the
unconformity of the two series cannot be insisted upon.” (Ib., p. 50.)
Prof. Carpenter, in 1888, said that the unconformity, supposed by New-
ton to exist, between the eastern slates and the western schists, is supported
by an observation made by him upon Spring Creek, east of Hill City,
(Geology and Mineral Resources of the Black Hills, 1888, (Carpenter)
p. 17), but more recently he has come to the conclusion that the separa-
tion between the eastern and the western, or earlier or later, rocks of the
Black Hills is of questionable existence.
Newton, in discussing the formations says: “The western series con-
sists of quartzose Schists and garnetiferous, quartzose and ferruginous mica
schists, together with some gneiss, chloritic and talcose (or hydro-mica)
schists, hornblendic schist and quartzite. The whole series is coarse in
texture and highly crystalline and it contains many seams or veins of
quartz, traversing the schists, conformable with the stratification and hav-
ing usually a swelling or lenticular structure. These veins are inter-
Jaminated and are not often of great width. They contain finely dis-
seminated gold and have probably afforded by their disintegration the
larger portion of the gold found in the valleys and gulches. The granite
masses are found wholly within the areas of the schistose rocks. The
eastern series is composed of metamorphic rocks, distinguished from the
western, mainly by their exceedingly fine and compact texture; though as
shown by Mr. Caswell, their ultimate mineral composition is quite similar.”
(Mr. Caswell made a report upon the microscopic structure of the rocks of
the Black Hills, collected by the same survey.) “The rocks are mainly
micaceous clay slate. siliceous slate and quartzite, the last forms persistent
strata from 50 to 200, and sometimes 500, feet in thickness, and can often
be traced for long distances with little variation. The quartzite fre-
quently contains seams or veins of interlaminated or ribbon quartz. Fre-
quently, the quartz seams are highly ſeruginous and in places they have
been found to contain undecomposed pyrites. Unquestionably they are
often auriferous.”
“The mica-schist is the prevailing mass characterizing the rock of the
GEOI.OGY OF , SOUTH DAKOTA. 29
western series, and its variation in character is very considerable. More
commonly it is the gray, tolerable fine, highly crystalline, uniform, mica-
ceous and siliceous schist, which, from its large proportion of mica,
weathers readily and uniformly. Very frequently, especially in the
western part of the area, it is so highly charged with garnets that it ac-
quires a dark, reddish color.” (Geology of the Black Hills, (Newton),
page 51).
‘These garnets are sometimes found, collected abundantly in the
streams. The mica schist changes sometimes into a hydro mica-schist
presenting the usual soapy feeling and general character of the talcose
schist. This being more coherent than the very micaceous rocks, more
pºem in topography and forms harder and rougher ridges.” (Ib.,
. 9%).
p §, a similar gradation the micaceous, pass through siliceous schists
into tough quartzite. The, quartzites are less developed in the western,
-than in the eastern series. They are among the most durable rocks and
in the Black Hills generally stand in abrupt dike-like ridges, running
with the stratification of the rocks. They commonly contain mica in small
quantities, and have an interior structure, or relation, indicating an intru
sive origin, and are of true metamorphic character. “Sometimes the mica-
schist passes by almost imperceptible gradation into true chloritic schist,
which is usually soft and easily decomposable, of a green color and no
mica readily visible to the eye. Crystals of ripidolite may often be picked
out with a knife, and it frequently contains garnets in abundance.”
(Geology of the Black Hills, p. 52).
“The quartzites vary in thickness from seams only a few inchs wide to
masses 400 or 500 feet in width, though the more moderate thickness, 75 to
100 feet, is more common. * * The color of the quartzites is varied, be-
ing sometimes an almost pure white, but more often a light or dark gray, or
impure blue, or pink, or, when much iron is contained, a dark and reddish
brown. In texture they are very compact and homogeneous, and on a
fresh fracture, which is conchoidal or fragmental, they have a vitreous or
glassy luster. They are almost pure quartz.”
“Though they are found throughout the series of slates, they are of
greater thickness in certain parts of the district. There exists on the
eastern border of the Archean area a long ridge or succession of prominent
peaks and bluffs which cuts across all of the creeks north of Harney Peak,
occasioning in each one an intricate, precipitous and exceedingly rough
canyon. This ridge and these canyons are due to a series of quartzite
strata.” (Geol. Black Hills (Newton), p. 58.) “A prominent deposit, or
accumulation of quartz, is found two or three miles east of Custer Peak, to
which the name of Jasper Hill was given. It is irregular in shape, about
200 feet in height without any clearly defined structure. The siliceous
material composing it display great variety in color and character.
Among them are a deep, red jasper and grayish quartzite of a pure white
mica or translucent quartz, which in places has a bright red crystalline
iron oxide running through it like the dendrites (plant-like crystals) in
moss-agate.” “A banded structure is found also in the quartzites.
Bands of iron ore, ferruginous strata of the inclosing rock, and seams
of ferruginous quartz are found in the quartzites, and though the separa-

30 GEOLOGY OF SOUTH DAKOTA.
tion between the ordinary quartz and the ferruginous or iron-bearing por-
tion is generally ill-defined, the latter are sometimes so well marked as to
run like a true vein within the body of the quartzite itself.” “In many
cases the ferruginous quartzite lodges are probably due to the original dis-
semination in the quartzite of iron oxides, which in the process of weather-
ing, are oxidized and hydrated to brown hematite. Sometimes, however,
they may arise from decomposition of pyrites.”
“The dip of the strata of the eastern series is always high, 70 to 90 de-
rees, and though it varies in amount and direction, it is usually toward
the west. The general strike is about 30 degrees west and it swings
now in one direction and now in another, ranging freely between the
limits of northeast and northwest.” (Ib., p. 60.)
“No fossils were found in the Archean rocks; and marble and serpent-
ine, the metamorphic rocks most likely to yield them, were not seen.”
Such are some of the most instructive statements which we glean from
Newton's report.
Professor C. R. Van Hise, in 1890, “finds that the prominent structures
of the Black Hills, which have heretofore been taken as bedding or strata,
are secondary structures produced by pressure, and as evidence of this is
the fact that alternate bands of sediments of different characters are seen
to cut across the prominent lamination of the rock. Sometimes these
bands contain pebbles which are clearly deformed by pressure. This fact
had been previously observed by Prof. Carpenter. (Geol. and Min. Res. of
the Black Hills (1888), p. 22.) The longer axis of the pebbles is par-
allel to the slaty or schistose structures; but the belt as a whole cuts
across this structure.” He calls attention to the fact that the dip of the
schists and slates is away from the granite area and indicates that their
lamination is due to pressure attending the eruption of the granite
masses in the south and of the porphyries further north. A study of the
boundary between the slate and schist series, noted by Newton, leads to
the conclusion that there is a graduation from the slates to the schists
rather than an abrupt change. He considers that the schists and slates
cannot be divided into two series. He finds also that the slates and
schists are most perfectly crystalline near the granite areas and near the
areas of eruptive rocks at the north end of the Hills: while more remote
from these points they show more distinctly a sedimentary character.
(Archean & Algonkian, 1892 (Van Hise), p. 259.) These conclusions of
Van Hise seem to the writer in harmony with the facts, particularly in the
vicinity of Harney Peak, where in passing from Hill City to Keystone,
the variation in dip from west around through north to east was very evi-
dent. Van Hise also calls attention to the fact that the repetition of
similar quartzite ridges probably indicates a folding of strata so that the
thickness of the Archean instead of being 100,000 feet, as supposed by
Newton, and also by Carpenter, may be indefinitely diminished.
# GEOLOGY OF SOUTH DAKOTA. ' 31
q
All previous writers have failed to find traces of marble and serpentine;
although Carpenter called attention to pebbles of limestone or marble in
the Cambrian. (Geol. and Min. Res., Black Hills (Carpenter), p. 29
and 23.) Recently a specimen of dark gray marble, banded with
lighter colors, was shown me by Mr. Lewis of Rapid City; and he in-
formed me that a bed of it, more than twenty feet in thickness had been
discovered in the slates at a point which he declined to reveal. And others
informed me that recently bouklers of a'similar rock had been found near
Rapid City. I find also that Carpenter, since the writing of the first part
of his report has found calcareous rocks on Box Elder creek. (Geol. and
Min. Res., Black Hills, p. 123.)
THE A.G.E OF THE BLACK HILLS AIR CHEAN ROCKS.
The Black Hills Archean rocks exhibit a remarkable lithological re-
semblance to certain rocks of the iron-bearing series of the Lake Superior
region, which in the past have been included under the term of Huronian;
although Prof. Van Hise has, in harmony with the recent decision of the
United States Geological Survey, applied to all these rocks the term “Al-
gonkian.” He considers that the tracing of this analogy, as was done by
Newton, is with good reason, although Crosby, (Proc. Boston Soc. Nat.
His, Vol. XXIII, p. 497), and Carpenter, (Geol. and Min. Res., Black
Hills, p. 24) have offered reasons why they should be classed with the Ta-
conic and Blake places portions of them with the Coos group. The latter,
however, rests mainly upon the presence of staurolite and, as Van Hise re-
marks, is little more than a guess. The division of the rocks into earlier and
later members is virtually disproved and the whole may be considered as one
formation, which was probably deposited as fine sediments derived from
older areas further west. This formation was metamorphosed and ren-
dered highly laminated when elevated into its present position, as the
prominence of quartz and feldspar would indicate. The resemblance be-
tween the Archean rocks of the Black Hills and those of the Lake Super-
ior region, known as Animikie, Penokee and Marquette series, Van Hise
gives substantially as follows: Both have mica schists and mica slates of
great thickness; both are certainly offragmental origin and contain staurolite
and garnets in certain cases. The thick beds of nearly pure quartzite and
quartzose conglomerates, which occur in the Black Hills correspond to the
quartzites and conglomerates in the Penokee and Marquette areas. Much
of the iron-bearing formations of the Lake Superior region have been
shown not to be mechanical sediments but rather chemical or organic sed-
iments which by subsequent alteration have been changed into the various
forms now found. Beds similar to these are found in the Black Hills. In
the Lake Superior region beds of important iron ore are known to belong
\
*
32 GEOLOGY OF SOUTH DAKOTA.
to this formation. Such have not yet been found in the Hills. In the
Lake Superior region are vast quantities of eruptive rocks, which occur in
dikes and intrusive beds in the fragmental series. Similar rocks in simi-
lar relative positions are found in the Hills. The chief lithological differ-
ence between the two regions is the presence in the Hills of large masses
of granite. The only parallel to those in the Lake Superior iron-bearing
series is found in one or two unimportant dikes. There is, therefore, a
striking analogy, but to admit a closer correlation seems useless as long
as geologists are not agreed as to the correlation of different portions of
the Lake Superior region itself. Bulletin G. S. A., Vol. 1, p. 241.
TIII: ORIGIN AND AGIC OF TIIB, GRANITE. <
This conspicuous deposit has been studied and remarked upon by sev-
eral eminent students. Crosby and Carpenter argue that the granite is
of metamorphic character, having at one time been of fragmental strala.
Their reasons are mainly drawn from the relation of the granite rocks in
Canada to the Huronian; and from the alteration of granite with the mica-
schists in the Black Hills and the lenticular form of the granite masses.
Crosby claims to have found fragments of the granite in the schists in-
dicating the earlier existance of the former. Newton, on the contrary,
early noted distinct signs of its eruptive origin, as for example, the existence
of irregular fragments of schists, some small and others of immense size,
imbedded in the granite as though the latter had been floated into posi-
tion by the former. Prof. Van Hise in studying the matter comes to the
same conclusion. We have already referred to the occurrence of granite
in dikes transverse to the lemination of the schists. From the present
evidence, therefore, there seems little doubt that the granite is an erup-
tive rock.
If the granite is of eruptive origin, it must be later than the deposition
of the schists and slates. How much later, becomes an interesting ques-
tion. That it was before the deposition of the Potsdam sandstone seems
to have been proved by the following facts: Newton found on French
Creek, as he states, “A continuous sheet of the Potsdam pass from the
surface of the eroded schists to the surface of granite. There was ſound
no intrusion of granite along the parting between the Potsdam and the
schists and there was found no metamorphism of the Potsdam at the
surface of contact with the granite. In these particulars the relation of
the granite is strongly contrasted with those of the trachyte of the Hills.
Wherever the trachyte appears beneath the Potsdam the later is uplifted
as though by the insertion of the trachyte between it and the Archean.
Its lowest beds are at the same time metamorphosed as though by the
heat of the molten intrusion. The fact that the granite did not at this lo-
Af f y”
} GEOILOGY OF SOUTH DAKOTA. 33
cality affect the form and constitution of the Potsdam strata in a manner
similar to the trachyte does not well accord with the idea that it was in-
troduced under similar conditions and during the same geological period.”
(Geology of the Black Hills (Newton), p. 78). He also discovered frag-
ments of feldspar which apparently come from the granite in the lower
portion of the Potsdam sandstone.
Prof. Headden observed similar phenomena in the vicinity of Hayward
on Battle Creek. He says further, that there can be no question that the
Potsdam is unconformable to the schists and that it rests upon the gran-
ite. He found also in the Potsdam conglomerate above Hayward besides
quartz, mica and feldspar, abundant crystals of tourmaline. Since no crys-
tals of this mineral, except of minute size, have been found anywhere but
in the granite, this is additional proof that the granite has furnished ma-
terial for the lower Potsdam. Therefore, the granite must have been
thrown up before the deposition of the Potsdam or Cambrian.
TIIE FORMATION OF THE SCHISTS AND SLATES.
We have already noted the fact that the schists and slates, and also
quartzites, are of fragmental origin. They were first deposited as shales,
sandstones or beds of sand in the primary ocean. The source of the ma-
terial has not yet been satisfactorily determined. Probably from areas
which have been since buried by later formations. After their deposi-
tion they were upheaved and probably folded by the force acting upon the
earth's crust, which doubtless forced upward the mass of granite in
a molten or semi-fluid condition, which found its way through fissures and
between the layers of the overlying clays and sandstones. By the heat
and pressure which was generated, these rocks were changed from their
from their original condition to their present form. By partial solution
and chemical action, they were changed to a crystalline state; while the
intense pressure acted mechanically upon their constituent grains and
produced lamination of the schists and slates with a distortion of the
boulders and pebbles, as has been noted in the quartzites of several lo-
calities.
The internal structure of these rocks has recently been very success-
fully studied by Prof. Van Hise. By a microscopic study of specimens
he has learned some very instructive facts. To the unaided eye the boul-
ders and the conglomerate quartzites, observed along the Box Elder Creek,
first by Crosby and Carpenter, show remarkable distortion, being elonga-
ted vertically, as though pressed by great force from two lateral direc-
tions. In some cases the pebbles and boulders have been distorted until
their lengths are three times their breadths. Crosby considers this dis-
tortion to have taken place by the slipping of individual grains of quartz
3
34 GEOLOGY OF SOUTH DAKOTA.
upon another. But Van Hise has found that the individual grains are
themselves elongated, having been subject to minute fracture and then
recemented by the deposition of quartz from solution. These features
have been shown in a most satisfactory way by his study. In the case
of schists there has not only been pressure but a shearing stress
which has ground and pressed the minute fragments, rendering them
more or less easily cleavable, perpendicular to the direction of the com-
pressing force. It is, therefore, generally agreed that the metamorphosis
of the crystalline schists, probably occurred in the southern portion of the
Hills at the time of the outflow of the granite, which probably took place
simultaneously with one of the elevations of the Hills; and that a similar
change took place in the north end of the Hills, either at the same time,
attending the irruption of the masses of granite, which are not well ex-
posed in that region, or else subsequently at the time of the outflows of
trachyte and rhyolite. The deposits of ore and other points of economic
value we will speak of in a subsequent chapter,
THE SIOUX QUARTZITE.
The Sioux quartzite occurs in the eastern end of the State and is a por-
tion of the peninsular area of rocks, extending from the vicinity of Red-
stone, Minn., west-southwest into Dakota. Areas of similar quartzites
occur further east in the ridges about Baraboo, Wis., and along the west
side of Chippeway Valley, Wis. This formation is very different from
those already described, consisting almost entirely of an intensely hard and
compact quartzite with no trace of lamination. It occurs in strata nearly
horizontal and is cut into blocks by vertical joints, from six inches to several
feet apart, and crossing one another nearly at right angles. This causes
the cliffs of this formation to resemble walls of masonry and not infre-
quently the upper surface reminds one strongly of a pavement. The oc-
curence of it in cliffs from fifty to sixty feet in height may be well seen
at Palisade and Dell Rapids. The occurrence of it, in broad and apparently
level areas, is well shown about Sioux Falls, north of Alexandria and at
Rockport, on the James river.
In color it varies from a light gray or nearly white, through shades of
pink to a dark purple and, in some cases, a dark Indian red. The pre-
valent colors are the light pink and the light purple. In some localities,
beds of it are beautifully variegated, the ripple-marks of the original
stone being brought out beautifully by alternate layers of light and dark
pink not more than ; or # inch in thickness, producing parallel and wavy
lines over the surface, reminding one of an agate on a large scale. In
hardness, it varies from a rock harder than steel, which breaks with a
splintery fracture, (its usual character), to beds scarcely consolidated,
PLATE II.—IPRINCIPAL FALL
OF THE BIGSIOUXRIVER OVER THE SIOUX QUARTZITE AT SIOUX FALLS,

GEOLOGY OF SOUTH DAKOTA. 35
W
which may be easily excavated with a spade or pick. A micro-
scopic study by Prof. Irving and Van Hise has brought to light a very in-
structive fact, viz.: that this consolidation has been produced by the en-
largement of the grains of the original sandstone by the deposition of
silica from solution, along the planes corresponding with the crystalline
axes of the original grains themselves. In cases where the beds are im-
perfectly consolidated, these crystals, though formed, have not grown
sufficiently to fill the space between, while in the compact quartzite the
spaces between the original grains havé been completely filled with silica
or quartz, so that the present rock is nearly solid quartz. Fracture is
apt to break through the original grains as readily as between them. This
is particularly striking where the quartzite is conglomerate, that is, con-
taining large pebbles of quartz, of different color from the main mass of
the rock.
THE EXTENT OF THE QUARTZITE.
It is almost everywhere deeply covered with a deposit of boulder clay
of comparatively recent origin, but from a few exposures which are
found along the valleys of streams and in wells, the outline of the quartzite
has been laid down as represented upon the map. It extends along the
east line of the State from near Flandreau to a little south of the north-
west corner of Iowa. Its western-most exposure is on Enemy Creek,
South of Mitchell, about two miles above its mouth. In its triangular
area between these points the drift is probably underlaid, generally, by
the quartzite. The margin, however, is doubtless quite irregular, some-
what like the margin of a peninsula, with inlets, promotories and bays,
which have been filled by rocks of the Cretaceous age.
The dip of the rocks is slight and quite irregular; no clear trace of folds
has been made out. There seems to be no prevalent trend to the dip.
The thickness of the formation has not been determined. Irving, from the
studies of Mr. Merriam, estimated that in the eastern portion of Minne-
haha county some 3,000 feet of it are exposed along the Split Rock creek,
about Palisade. From our study, so great a thickness seems doubtful,
and we should consider 1,500 feet a generous estimate. The dip, so far
as observed, nowhere reaches 10 degrees and its average may be placed
at less than 5 degrees. A list of localities where it is exposed will be
found in the chapter on Economic Geology. The dip seems to be that of
the original deposition rather than of flexures of the earth's crust. The
other rocks associated with the quartzite are the pipestone and an erup-
tive diabase. The former has been longest known at Pipestone, Minn.,
where it occurs in a thin layer about 18 inches in thickness, lying between
and conformable with the quartzite. Mr. Upham, of the Minnesota Geo-
logical Survey, in the Thirteenth Annual Report, reports the occurrence
of a similar Pipestone near Palisade, S. D. He says:
36 GEOLOGY OF SOUTH FDAKOTA.
|
“The quartzite in this vicinity embraces two layers, each several feet
in thickness, of compact, fine grained, red rock, easily cut and polished,
closely resembling the Catlinite of the Pipestone quarry in Minnesota.
The upper one of these layers is seen a quarter of a mile from the mill on
the northwest side of the creek, where it has been quarried and is called
slate. Its vertical exposure in the quarry is 7 feet, and its base, though
probably not much deeper, is not seen. It lies in sheets from of an
inch to 6 inches in thickness, dipping about 2 degrees, south 30 degrees
west. The lower one of the chalk layers is called Pipestone and is
scarcely inferior in quality to that of the noted Indian quarry at Pipe-
stone, Minnesota. This bed is exposed about five rods east of the dam,
and some thirty rods east of the mill, where it is seen to have a thickness
of at least 4 feet—it may be as much as 7 feet thick; divided into sheets
from a half inch to 3 or 4 inches thick. It dips 6 or 7 degrees,
south 60 degrees west.” (Thirteenth Annual Report Minnesota Survey,
1884, p. 94.) He also says that “twenty rods east of the dam, at the
Palisades, and about 20 or 25 feet above this dam is a deposit of so-
called “chalk-rock,” which has a vertical thickness of 4 feet and dipping the
same as the quartzite. The upper part of the bed is soft, being scarcely
harder than many shale beds, is white above, being pink and harder below.
By chemical analysis it has been found to correspond closely with the
pipestone in composition.”
He reports still another exposure twelve miles northwest of Sioux Falls.
(Thirteenth Annual Report, Minnesota Survey, 1894, p. 91.) The Pipe-
stone or Catlinite, as it has been called, is now considered to be meta-
morphosed clay.
An exposure of a similar formation has been found about two miles
southwest of Bridgewater on Wolf creek, where it was readily used for
marking, like chalk.
Eruptive rocks forming dikes have been found in the quartzites south-
west of Palisades, Sections 15 and 22, Township 102, 48. This locality
was found by me in 1885, and the rock examined by Prof. C. W. Hall of
Minnesota University. Prof. Hobbs, of Wisconsin University, published
a description in 1892. (Trans. Wis. Acad. Sci., Vol. VIII., p. 206.)
The granites near Big Stone Lake, which are barely exposed in our
State, are thus described by the Minnesota geologists:
“They are generally gneissic instead of massive. They are more
frequently true granite. They are always red. While their lamina-
ted structure renders them more easily wrought, and thus gives them
an advantage over the firmer syenites of the Mississippi Valley, it also
renders them softer and more destructible under the action of weather.
They seem to have less quartz and more of the cleavable minerals, feld-
spar and mica. Still there are exceptions to the gneissoid structure of
the Mississippi Valley granites.” (Minn. Geol. Rep., Vol. 1, p. 146).
These rocks are probably the oldest in our State.
CHAPTER V.
THE PALEOZOIC FORMATIONS. ;
Following the deposition of the schists and slates, was a period of dis-
turbance and erosion of indefinite length. As has already been indicated,
the Potsdam formation lies upon the upturned edges of the schists. Of
the different Paleozonic ages we find deposits only of the Cambrian, Silu-
rian and Carboniferous, with a slight representation, possibly, of the De-
vonian. All these are found only in the Black Hills, and lie conformable
to one another, and with gentle regular dip away from the Archean core
of the Hills.
TIIIE CAMIBJRIA N.
ryº
The Cambrian is represented by a full development of the Potsdam
sandstone. This formation was first recognized from fossils collected and
observations made by Dr. Hayden during Warren's reconnaissance of the
Hills. The formation is very fossiliferous, containing the characteristic
genera of the Potsdam, found in the east, Lingula, Lingulepis, Obolella,
Flyoletis, with trilobites, fucoids, etc. The Potsdam has been found
in many places along the flanks of the Rocky Mountains, but in no other
locality has it been found so abundantly fossiliferous as in the area of the
Black Hills. This formation is the lowest member of the fossiliferous
series of rocks, and in its numerous exposures its character and relation are
easily determined and studied. It consists mainly of coarse and friable
sandstone, conglomerates and shaly sandstones. The ease with which the
formation is eroded has caused it to be removed, except where protected
by a harder and laterformation. It, therefore, is exposed mainly in a belt
of cliffs or bluffs overlooking the Archean area of the Hills, on all sides,
like a wall. Through this, the various streams have cut canyons whose
sides are mainly formed of Carboniferous rocks, with Potsdam at their
bases, resting upon the Archean. Occasionally near the cliffs the fossil-
iferous rocks are merely isolated beds of Carboniferous limestone with the
underlying Potsdam, which have been left by denudation in the midst of
the Archean; but on account of the friable and easily eroded character
the Potsdam, out-liers of that formation alone are not very frequent. In
the northern parts of the Hills, however, in the region northeast of Cus-
38 GEOLOGY OF SOUTH DAKOTA.
i ^
ter Peak, large areas of the Potsdam are exposed. Around Crow Peak,
where the strata have been upturned by the extrusion of the trachyte
which composed the mass of the peak, the Potsdam stands nearly vertical
against the volcanic rock and has been transformed into a hard, white
quartzite. At other points, also, the Potsdam has been similarly up-
turned and metamorphosed by the eruption of volcanic rocks. (Geology
Black Hills, p. 83).
Upon the geological map a narrow band along the interior of the Pale-
"zoic area may be considered as répresenting the Potsdam. Near Terry
Peak there is considerable surface covered with it.
The formation ranges in thickness from 200 to 250 feet, but is said to
attain 300 feet on the north branch of Red Water Creek. The forma-
tion distinctly thins out toward the center of the Hills. Dr. Carpenter
reports an exposure of only 50 feet near Harney Peak. Its thickness
corresponds well with the conception of its being formed around the
Archean island, which was barely covered. The basal conglomerate
varies in character and thickness in different parts of the Hills,
sometimes within short distances, but is everywhere a well-worn shore
deposit. The pebbles and boulders, forming the conglomerates, were
examined by Newton with minute care and were found in all cases
to consist of a harder variety of rocks composing the metamorphic
series, quartz, hard, blue and gray quartzites, and some of the
harder slates, and schists. The latter usually occur as flattened peb-
bles similar to those found in the present streams. There are deposits con-
taining a few felspathic pebbles and in some places crystals of tourmaline
from the granite. In the upper portion of the main conglomerate and in
occasional fine conglomerate, occurring in the body of the formation, the
constituent pebbles are almost entirely of quartz. Sometimes the boul-
ders or cobble stones forming conglomerates are from 1 to 4 feet in diam-
eter. One of the best exposures of this character was noted by Newton
in the canyon of Lower Rapid Creek. A similar heavy conglomerate
formation is found in many other parts of the Hills. In some places the
conglomerate is found above the base of the formation, in which cases the
pebbles seem to have been formed from previously existing portions of
the sandstone. A good exemple of this is reported by Newton, near the
eastern base of Terry Peak. Prof. Carpenter made an interesting discov-
ery that many of the pebbles in certain layers of the conglomerates were
of crystalline limestone. At the time of his report he had not discovered
the source, but they correspond well in color and structure to the gray
marble, to which reference has been made as found in the Archean.
The cementing material of the conglomerate is generally silica and is
reinforced, often with oxide of iron. The calcareous cement, sometimes
GEOLOGY OF SOUTH DAKOTA. 39
}
occuring often contains the remains of fossils and grains of green-sand or
glauconite. Some of the coarser conglomerates are sometimes scarcely
cemented at all.
The Potsdam sandstone of the Hills might be described, with almost
the same words that have been employed by different observers in describ-
ing the Potsdam of the eastern part of the United States. Its color is us-
ually rusty or dark brown, although above, it may be in places nearly
white. It sometimes contains small scales of mica, and grains of harder
metamorphic rocks, but it generally consists wholly of quartz grains.
These vary from the minutest size to that of a pin head or small grain of
rice. In texture it varies from an almost incoherent mass of sand, easily
crumbling on exposure to the weather, to a dense compact sandstone
which forms durable cliffs. Sometimes it passes into a quartzite of silice-
ous grains embedded in a bright glassy, siliceous cement. The most
friable kinds are light in color and usually have a ferruginous cement, while
the red or brown, in which the cementing material largely exceed the iron,
are usually more compact and durable. In many places the sandstone is
somewhat argillaceous, and in others, of shaly character, usually with a
darker color.
Though the sandstones are coarse in texture they carry in many places
abundant fossil remains in an excellent state of preservation. Complete
sections of the formation from base to summit are rarely met with, because
of the concealment of the slope by broken fragments from the Carbonif-
erous beds from above, as well as by those formed from its own incoherent lay-
ers. The following section from the canyon of Spring Creek is given as a
representative one from measurements made by Prof. J enney. Geol. of
Black Hills, p. 88.
CARBONIFEROUS— |
5. Limestone with Spirifera, Productºs, etc., - - - - - - - - - -335 feet
4. Reddish brown or pinkish calcareous sandstone, thinly
bedded, containing Spirifera camerata, Cyathopylloid
corals and crinoid stems - - - - - - - - - - - - - - - - - - - - - - - - 20 feet
PoTSDAM—
3. Reddish-brown sandstones, thinly bedded at base, and
alternating with soft yellow sandstones, containin
large fucoids, Lingulepis and fragments of trilobites.200 feet
2. Brownish yellow conglomerate, with quartz pebbles,
resting uncomformably on the next, and dipping 25
degrees northeast------------- - - - - - - - - - - - - - - - - - - 25 feet
ARCIIEAN–
Argillaceous slates, dipping 60 degrees west.
Another section is given by Newton from lower Rapid Creek. (Geol.
Black Hills, p. 94.)
40 GEOLOGY OF SOUTH DAKOTA.
CARBONIFEROUS—
10. Gray limestone stained at base with iron - - - - - - - - - - - 80 feet
9. Pinkish and yellowish limestone, thin bedded, contain-
ing a few Carboniferous corals and brachiopod frag-
ments----------------------------------------- 33 feet
8. Pink and yellowish limestone, gray at top -- - - - - - - - - 40 feet
POTSDAM—
7. Red and yellow sandstone with bright quartz grains,
cross-stratified and containing at base considerable
6. Reddish calcareous sandstone, with glauconite---- - - - 4 feet
calcareous matter------------------------------- 70 feet
5. Red and pink impure shaly limestone with green
glauconite grains, sandy at bottom - - - - - - - - - - - - - - - - 50 feet
4. Red and brown shale with somethin strata of limestone
and large quantities of glauconite- - - - - - - - - - - - - - - - - 80 feet
3. Impure shaly limestone with some clay shaly, yellow-
ish and reddish--------------------------------- 20 feet
2. Massive yellow and reddish sandstone, highly calcare-
ous, dipping northeast 20 degrees-- - - - - - - - - - - - - - - - 50 feet
ARCHEAN–
1. Argillaceous slates in the bed, of the creek; strike
north 15 degrees west; dip vertical.
Another section upon Slate Creek above its junction with Castle Creek
was observed by Prof. Jenney.
CARBONIFEROUS—
8. White, pinkish and grayish and siliceous limestone
with Spirifera camerata, Productus, etc. - - - - - - - - - - - 100 feet
7. White compact limestone, containing some fossils -- - - 100 feet
6. Unexposed slope-------------------------------- 250 feet
POTSDAM—
5. Soft brown sandstone, containing abundant fossils,
Lingulepis, Obolella, trilobite fragments - - - - - - - - - - - 50 feet
4. Coarse ground brownish yellow sandstone with small
quartz pebbles merging into bed 3- - - - - - - - - - - - - - - - 50 feet
3. Conglomerate of quartz, bowlders and pebbles, ce-
mented by sand and oxide of iron with some lime- - - - 55 feet
2. Unexposed slope --------- - - - - - - - - - - - - - - - - - - - - - - 85 feet
ARCHEAN–
1. Chloritic, talcose and mica schists; dip 55 degrees west;
strike north to northwest -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
The sandstones are often riddled with small holes, perpendicular to the
bedding, 1 to 3 or more inches in length, and about one-eight of an inch
in diameter, often with rounded termination. These are special char-
acteristics of the white sandstone and occur more frequently in the upper
GEOLOGY OF SOUTH DAKOTA. 41
t
beds of the formation. These were supposed formerly to be the casts of
seaweed stems, but it is now generally considered that they are worm
burrows; while some consider them the casts of fleshy peduncles of certain
brachiopods like Lingula. Their real nature is still an open question.
They are known as Scolithslinearis, and others apply the general
name Arenicolites. Fossils are sufficiently well preserved to be clearly
recognized; though they do not occur except in a few localities and in
particular layers. According to Newton near the headwaters of Red
Canyon Creek in the northwestern corner of the Hills the Potsdam, with
its usual soft sandstone character, is underlaid by a bed of quartzite which
rests upon the upturned mica-schists. This quartzite consists of small
grains. The color is deep brownish or purplish red, slightly tinted with
green. The entine mass is filled with fossil remains, Lingula, Lingulepis,
Obolella, etc., in a beautiful state of preservation, yielding the best collec-
tion of fossils obtained from the Potsdam in the Hills.
Another interesting class of fossils, quite abundant in the layers of the
Potsdam, are the casts of fucoids. Commonly they are of ordinary
size, and a few inches in length. But Newton reports a discovery of
strata on Spring creek with casts of a fucoid, named Paleophycus occiden-
talis in the shaly argillaceous sandstone, some of the specimens of which
are five or six feet in length. The main stem is nearly an inch in diameter
and divides into numerous branches ; of an inch through. The stems
usually divide into threes or twos and the smaller branches frequently
terminate abruptly in rounded ends.
The Potsdam contains layers of quartzite, not only at the base and in
the vicinity of igneous rocks, but at irregular intervals and different lo-
calities, in a way that is diffieult to explain. Not only in the locality of
Red Canyon creek, but about the headwaters of Amphibious and Beaver
creeks, and on the same creek near the beginning of the limestone canyon:
but also on Burnt-Wood creek, on French creek and near the Battle creek.
Quartzites are found at the base of the Potsdam, where it lies in contact
with the Archean. In some cases it attains a thickness of about fifty feet.
This position of the quartzite has been observed elsewhere in the Rocky
mountains and the Wasatch mountains. The quartzites found in the
body of the formation piffer somewhat in their character from those just
described. They are, according to Newton, best observed and studied
on Box Elder creek. There they occur as deep red or purplish layers, in-
terstratified with coarse red sandstone. Intercalated quartzite strata are also
seen on Frenclºcreek, where the color is yellowish-brown. They differ
from the quartzites of the slates and schists of the Archean in consisting
of smaller grains. In some cases the quartzites weather into a coarse
sandstone which readily crumbles, the siliceous cement having been re-
moved.
^
42 GEO LOGY OF SOUTH DAKOTA.
This unusual hardening of the sandstone can hardly be referred to or-
dinary causes or conditions of metamorphism, but rather to the local
abundance and deposition of soluable silica. Such is known to be de-
rived from certain organic substances of diatoms, sponges, etc. (Geol.
Black Hills, pp. 89–92) *
A peculiar feature of the Potsdam, which has already been mentioned,
is the abundance, in certain layers, of glauconite.
“These grains are rarely over a tenth of an inch in their larger diameter
and the majority are not more than one-half that size. They are usu-
ally flattened and appears as flat flakes of irregular shape and are usually
smooth and rounded as though water-worn. Their color is a dark olive
green, sometimes nearly black. They are only slightly acted upon by
strong hydrochloric acid. Before a blowpipe they resemble perfectly
the greensand grain of the Cretaceous in New Jersey.” (Geol. Black
Hills, p. 95.)
Glauconite or greensand is a hydro-silicate of protoxide of iron and
potash, with a variable amount of alumina.
A word concerning the general characters of the life of this first Pale-
ozoic formation will be of interest to the general reader. There were as
yet no form of vertebrate life nor of land plants. The formations
most abundant were such as are now found near the surface of the sea
and along the shores in shallow water. The particular types, however,
were very unlike those of the present in species and even in genera.
The larger forms were trilobites, which were but a few inches in length,
and might be described as broad, flat, worm-like animals, adapted for
creeping in mud or swimming in still water. The Scolithus burrows were
probably formed by worms buried most of the time in the sand, somewhat
like the Arenicola, or lobworm, of our present seashore. There were
shells resembling the smaller sea-snails of the present time, and a few
like the smaller clams, but the most abundant shells were those of brachi-
opods, which are not abundant at the present time and may be described
as burrowing worms, having their heads protected by small helmet-like
shells. These shells are bivalved, and are often mistaken by common ob-
servers for the bivalved shells of clams.
THE SILURIAN,
Newton in his study of the Hills discovered formations belonging to
only two of the ages of Paleozoic time. Those already described he rec-
ognized as Potsdam or Cambrian, the rest he classified as Carboniferous,
and makes no note of finding fossils representing the two intervening ages,
the Silurian and Devonian. Dr. Carpenter in his report also speaks of
but two, the Cambrian and Carboniferous, but adds in the foot-note that
he has received, since writing the body of his work, certain fossils from
GEOLOGY OF SOUTH DAKOTA. 43
Prof. A. T. Free, of Deadwood, helonging to the Silurian. (Geol. and
Min. Res., Black Hills, 1888, p. 34, foot-note.) Since the publication of
Prof. Carpenter's report, he has visited the Deadwood locality and in theim-
provements going on at that point, a fine exposure has been made of the
formations intervening between the top of the Potsdam and the bottom
of the limestone beds containing Carboniferous fossils. He visited the
locality with me where we found abundant fossils in a bluff colored lime-
stone, 25 or 30 feet in thickness. It is argillaceous above, becoming quite
sandy below. He informed me also that numerous fossils had been for-
warded to the United States Geological Survey and theat several of them
had been identified, as belonging to the Silurian; but I am not aware that
the existence of the Silurian formation in the Black Hills, or even in the
Rocky Mountains has yet been distinctly published. The knowledge of .
this formation began in 1888.
Between this limestone foration, which is presumably the Trenton,
and the top of the Potsdam, there is found a layer of greenish laminated
clay, without coarse material and without fossils. The fossils found in
this limestone consist of a large species of Orthoceras or Ormoceras, Ma-
clurea, Halysites, Columnaria(?), Stromatopora and Tetradium. The
stone is thick-bedded, and reminds one of the buff limestone found in
southern Wisconsin. So far as yet known, no other exposure of this
Silurian formation has been] found in the Hills, yet a Cyathophylloid
coral and fragments of other fossils, resembling those of the Trenton forma-
tion, were noted on the headwaters of Beaver or Amphibious Creek.
This limestone may possibly represent the three prominent limestone
formations of the Silurian and Devonian, corresponding to the cliff lime-
stone found in the eastern portion of the Mississippi valley, in Ohio.
TIE DEVONIAN.
Between the well defined top of the Trenton and the base of the lower
Carboniferous limestone, there is found, in the Deadwood section, twenty
or twenty-five feet of lead colored and laminated clay or shale without
fossils. This represents the Devonian, if any formation of that age exists
in that section. At other points also, between the Potsdam and the
Carboniferous, has been noted this clay bed. Prof. Crosby suggests that
this clay may be deep sea deposits corresponding to the deep sea siz
reported from the Challenger expedition. (Proceedings of Bost. Sve.
Nat. Hist, Vol. XXIII, p. 505.) He calls attention to the very slow ac-
cumulation of deposits in the deep sea areas as brought by the dredging
of the Challenger. Referring to the bringing up of huge shark's teeth
from the bottom of the Pacific ocean, resembling closely those of the
species which existed in early Tertiary times, he infers that the rate of
increase of the sediments has probably been less than one foot, and pos-
44 GEOLOGY OF SOUTH DAKOTA.
sibly not more than two or three inches, in a million of years. Thus he
follows out the suggestion, made by Mr. Murray of the Challenger ex-
pedition. He suggests that, while the tens of thousands of feet of De-
vonian and Silurian rocks were accumulating in the Appalachian region
and also in the western portion of the United States, the Black Hills were
so remote from land that only a few feet of clays had accumulated there.
Prof. Carpenter quotes this suggestion with approval. The discovery of
the Silurian limestone will shorten the time represented by the clays very
considerably; but it is still difficult to understand how this point should
be so remote from land. As no trace of Paleozoic rocks have been found
in the eastern portion of our State, but pn the contrary signs of a surface
long exposed to erosion, we are driven to the conclusion that the shore
line of the ancient Silurian and Devonian seas must have been less than
300 miles from the Black Hills and probably within half that distance.
Hence, the conception that the absence of deposition was mainly due to
the remoteness from land seems untenable. The Devonian formations in
the west are usually thin and of a soft and easily disintegrated material.
THE CARBONIFEROUS ROCKS.
These are commonly divided into a Lower or Sub-Carboniferous and an
Upper Carboniferous, to which by some a third transitional period is added,
the Permian. This, as the name implies, (coal-bearing) is the formation in
which the vast coal beds of Europe and eastern America are found. But west
of the meridian of Omaha, in the United States, it is usually without im-
portant carbonaceous deposits. Prof. Newton, from his study of the
Black Hills, reports himself unable to affirm or deny the presence either
of the Sub-Carboniferous or of the Permian. The rock series is definitely
and constantly divided into several members, but the lowest and the
highest of these members alike failed to afford him distinctive fossils. The
local sub-divisions he recognized as four in number, which are distin-
guished purely by lithological characters. (Geol. Black Hills, p. 108.)
This is his general section of the Carboniferous, arranged stratigraphic-
ally:
TITE ALTERNATING SERIES-
5. A variegated sandstone, irregular, stained, red-
dish, yellowish and white, somewhat argillaceous
and calcareous and exhibiting little stratification,
weathering in peculiarly twisted, contorted (curly)
bands -------------. - - - - - - - - - - - - - - - - - - - - - -100-150 feet
4. No 5 passes below into a series of alternating
beds of pink and light colored sandstones and
limestones, somewhat argillaceous. The lime-
stone, apparently somewhat magnesian and poor
in fossils ------------------------------- - - 150–200 feet
* GEOLOGY OF SOUTH DAKOTA. 45
SILIGIOUS LIMESTONE—
3. Weathering usually in a peculiarly brecciated
manner, somewhat cavernous and often stained
with pinkish and reddish streaks, containing much
flinty and siliceous matter, often with a banded
structure; with crystals of calcite, lining the inter-
ior of weathered caves and crevices. Fossils are
found, but usually ill preserved, and only ex-
posed and obtainable when the rock is much
weathered. There have been recognized Athy-
ris subtilita, Spirifera Rocky-Montana, Productus,
corals, etc --------------------------------- 150–175 feet
GRAY LIMESTONE–
2. Massive gray or whitish limestone uniformly pure,
containing Spirifera Rocky-Montana, Productus,
etc --------------------------------------- 150–200 feet
SHALY LIMESTONE–
1. Thinly bedded, impure arenaceous limestone,
pinkish in color, often filled with comminuted
d fragments of crinoidal columns, and contains also
Productus, Cyathophylloid, corals, etc - - - - - - - - - - 20–60 feet
It will be seen from this that the prevalent rock here, as in other por-
tions of the west, is limestone. The sandstone or upper division seems to
have been first observed by Prof. Winchell, and was named by him “Min-
ne-Lusa Sandstone.”
Everywhere the Carboniferous is conformable or parallel with the Silur-
ian and Cambrian. This indicates that the deposition of sediments dur-
ing Paleonzoic times went on continuously and quietly without any marked
disturbance of the region. The Carboniferous rocks, over much of the
central portion of the Black Hills, lie nearly hortizontal and pass from the
high table lands in the Hills to the plain outside with an abrupt mono-
clinal fold. The formation of this fold is of later date. The slope of the
higher level of the Hills was probably at first nearly continuous with
that of the deeply covered beds around the Hills; and according to New-
ton they were uplifted bodily, in a comparatively short time, subsequent
to the Cretaceous. (Geol., Black Hills, p. 222.) But Prof. Carpenter has
pointed out that the formations of the Potsdam and the Cretaceous are
thinner toward the center of the Hills. Such facts indicate that the up-
lifts were gradual and the later one perhaps began in the latter part of
Carboniferous time. (Geol. and Min. Res., Black Hills, p. 27.)
46 h GEOILOGY OF SOUTH DAKOTA.
A DETA II, ED DESCRIPTION OF THE CARBONIFEROUS ROCKS.
The lowest member of the Carboniferous weathers easily and is not gen-
erally well exposed, though separation between it and the heavy lime-
stone above, is quite distinct where observable. It has a pinkish or gray-
ish color, is never a pure limestone, commonly has an argillaceous or
clayey appearance. Its strata rarely exceed 8 or 10 inches in thickness
and are often so thinly bedded as to resemble calcareous shale. Though
it contains many fossils, they are not sufficiently well preserved for identi-
fication. Zaphrentis, Spirifera and Productus are recognized. Geol.
Black Hills, p. 109.) This basal member is found at various places along
the eastern margin of the plateau, where it is distinguished by great
quantities of fragments of crinoid stems.
“The second member, a massive gray limestone, and the third a silicious
limestone are the most persistent features of the formation in the Hills.
They were well seen in nearly all parts of the country visited. Along
the eastern edge of the western plateau, however, there are considerable
areas over which the silicious limestone and part of the gray have disap-
eared by denudation; and for this reason one who enters the Hills from
the west obtains an inadequate idea of the true prominence of the Carbon-
iferous formation. Complete sections of the Carboniferous are found only
in the canyons cut by the streams as they pass from the hills to the plains,
and even there it is not always possible to study them closely in detail.”
(Geol. Black Hills, p. 110.)
The gray limestone is well exposed in every examined section of the
Carboniferous rocks. It is very uniform, its fossils are numerous and not
easily separable from the rock, except where it has been so greatly weath-
ered as to destroy their surface markings. The few species observed ap-
pear to be equally characteristic of the overlying silicious limestone.
(Geol. Black Hills, p. 110.)
The third member, or the silicious limestone, “is a hard, white or grayish,
gritty rock, which from the oxidation of its iron and perhaps also of per-
colation from the overlying rock, is generally stained, irregularly red or
pinkish. It contains much silicious matter, concentrated in spots, either
as flint, or as crystallie quartz, lining small cavaties or in concretionary
or agate like deposits. From its silicious and uneven composition it de-
composes very irregularly, often having a brecciated appearance and
weathering with cavities or crevices, and even with caverns of considerable
extent. The cavities are usually lined with crystals of calcite.
The most abundant fossils in the two limestones are Spirifera Rocky-
Montana, Athyris subtilita, Produtus, Euomphatus and Streptorhyncras.
“Immediately overlying and conforming to the silicious limestone are
the following beds: First. A series of thinly bedded sandstones and
impure limestones, the latter somewhat magnesian, varying in color—
pink, white, yellow and gray; the limestones contain only traces of fossil
GEOLOGY OF SOUTH DAKOTA. 47
#
remains. These have altogether a thickness of 150 to 200 feet, and pass
gradually into (second) a sandstone somewhat argillaceous and calcareous
of a deep red color, but often streaked or variegated with yellow or pink.
Frequently on fracture the sandstone has a somewhat lighter color or is
almost white; and while much of the predominating deep coloration is
derived from the oxidation of iron in the rock itself, a considerable por-
tion is also produced through staining by a downward infiltration from
the red clay above. It generally shows little or no stratification and is
massive, but it weathers in a becoiated or broken manner, with twisted or
bent lines of decomposition parallel with the general stratification of the
rocks. It has a thickness of 100 to 150 feet, making the entire thickness
of the upper or fourth member of the Carboniferous 250 to 350 feet.”
(Geology Black Hills, page 111.)
While the lower members of the formation (Carboniferous) are well
marked and easily traced and readily distinguished from each other as well
as from the underlying Potsdam, a study of the upper portion was at-
tended with no little difficulty. In the absence of distinct fossils the up-
per boundary of the formation had to be drawn from the lithological
character of the deposits. (Geol. Black Hills, page 110.) The de-
tailed section upon which these decisions are based have in part already
been given in connection with the Potsdam, and others will be found in
the discussion of the separation between the Carboniferous and the over-
lying Triassic rocks.
We may add that since Newton's work the cavernous character of the
silicious limestone has been remarkably developed and several extensive
caverns are now places of resort for pleasure seekers.
CRYSTAI, CAVE,
The mouth of this cave is overlooking the canyon of Elk Creek, about
six miles above Piedmont. It is about 200 feet above the level of the
stream, and approximately 4,202 above the sea. By the courtesy of Mr.
McLemore, the custodian of the cave, I spent several hours in exploring
the various chambers of this celebrated cave. The chambers present the
usual irregularities of valted caverns and narrow winding passage ways.
They are commonly covered with crystals of calcite of the usual form,
known as Dog Tooth Spar. Some chambers present beautiful ex-
amples of stalactites and stalagmites, and a few samples of a particular
form of surface, known as “box work,” are found, but are so deeply cov-
ered with calcite that they do not appear prominently. The passages, so
far as visited, rarely showed places of dripping water, and nowhere
running streams or large ponds, though Mr. McLemore assured me that
in some of the deeper passages such had been found. Many of the pas-
sage ways showed such an arrangement of the crystals as indicated that
they had been filled with water, and in the more open places with flowing
48 GEOLOGY OF SOUTH DAKOTA.
%
water. This was evident, whether we conceive the crystals to have been
first formed and afterwards partially dissolved, or whether the motion of
the water had prevented the complete formation of the crystals about the
exposed points. The crystalline surfaces were nearly smooth at points
where the currents, passing through the passage ways, would naturally
strike the walls, while in recesses they were sharp and complete. Crystals
were of quite uniform size, generally with a diameter of one-half to three-
quarter inches. Another evidence of occupation by water, and which in-
dicated also that the forms of the crystals was probably due to solution
rather than imperfect crystallization, was the coating of the crystals, very
generally, with a thin film of clay. This was especially the case in the
lower portions of the channels and chambers. Beautiful specimens of
spongy-shaped masses of crystals, formed in shallow basins of standing
water, have been found in this cave, sometimes of a straw color, but more
frequently of snow white or pearly luster. This cave is the property of
Keith and Allabaugh, of Deadwood, who prepared an artificial cave, lined
with crystals from this cave, at the World's Fair, where they are said to
have realized a handsome fortune from the sale of specimens.
The length of passages may safely be put down as several miles.
From the nature of the cave it has not yet been fully explored. The depth,
to the lowest point visited, below the entrance, was about 150 feet. The
larger chambers, in some cases, may be roughly estimated as having a
length of 200 or 300 feet. The breadth, 50 or 60 feet, and the height 30.
to 40 feet. There are reports of several other caves in the vicinity, which
have not yet been explored.
WIND CAVE,
The proprietor of this cave is Mr. J. D. McDonald, who has, with com-
mendable enterprise and much labor, enlarged the passageways and fur-
nished comfortable accommodations in various ways, so that this cave is
readily accessible to the public. He showed me many courtesies during
my examination of the cave, for which I here make cheerful acknowledg-
ment. The Wind Cave obtained its name from its alternately throwing
out and drawing in vast quantities of air. This phenomenon is found to
correspond with the varying pressure of the barometer; and with its single
opening and capacious chambers is easily accounted for. Its mouth is sit-
uated in the bottom of a ravine leading into Beaver Creek, on Sec. 2, Twp.
6 S., R. 2 W. This cave is also dry and presents the usual features of
narrow passages and irregular chambers like those of the Crystal Cave.
Their arrangement, however, is very regular. The dip of the rock is to-
ward the southeast, from 5 to 10 degrees. It is traversed by long verti-
cal fissures at quite regular intervals, running northwest-southeast. The
©
;
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&
•
;
i.
i
;
; *
GEOLOGY OF SOUTH DAKOTA. 49
%
erosion of subterranean waters has widened the fissures, and has excavated
small, low, irregular passageways from one to another nearly at right
angles. The larger chambers lie along the line of the fissures. Three or
four stories have been traced in the arrangements of the chambers. There
have been no careful measurements of the distances in this cavern, but it
is estimated that the easternmost point must be several miles from its
mouth, which is upon the west side of the cavern. The number of pas-
sages may safely be estimated to amount to a score of miles. The lowest
depth yet explored is about 225 feet below the mouth of the cave and the
altitude of the mouth, according to the topographers of the United States
Geological Survey, is 4040. There are but few places where trickling
water is found, and these may be traced to deep ravines, traversing the
vicinity east of the mouth. In fact these passages seem generally to be
below the beds of the present streams. In places, under ravines, beautiful
stalactites are formed, sometimes of ribbon-like outline and sometimes with
stalagmites below, forming pillars, but nowhere upon so grand a scale
as in some of the eastern caverns. Some of the chambers rise to a height
of 60 or 80 feet and one is reported to cover nearly three acres. The
cave is remarkable for the variety and delicate beauty of its encrusting
crystals and other formations.
One very abundant formation, lining the cavities on all sides, is appro-
priately called “boxwork.” This seems to have been formed in the fol-
lowing way: The rock is an impure limestone which has been cracked
into small polygonal masses more or less rectangular in cross-sections.
These blocks vary in size from an inch or two to a foot or more. The
cracks have at some time been filled with calcite, often in thin plates,
though in other places thick and heavy. The rock showing this con-
dition is found exposed upon the surface in the vicinity. In the atmos-
phere of the cavern the process of disintegration of the original limestone,
by dissolving away the natural cement, in some way not yet under-
stood, allows the grains of sand to run out of the polygonal spaces
formed by the calcite seams, somewhat as in an hour-glass. Since the
boxes were emptied, the calcite partitions have been coated with cal-
cite and aragonite crystals of various sizes and colors. Colors vary from
snow white to chocolate brown and honey yellow, and display not only a
“drusy” appearance and beautifully tufted and clustered forms, some re-
rembling grapes, and others like branching corals, but also forms most
perfectly resembling hoar frost. The boxwork abounds as a lining for
most of the passages and chambers, and is found to be limited to certain
layers. All stages in the process described may be found illustrated.
Although the boxes may possibly in some cases be now closed, that
feature seems to have resulted from a later deposition of crystals, and it
4
50 GEOLOGY OF SOUTH DAKOTA.
may be assumed that they were once open for an escape of the enclosed
material. The bottom of the chambers are often covered with sand.
These crystalline forms occur alsó elsewhere than in the boxwork.
The origin of the beautiful frost-like crystals is one of the interesting
problems of the cave. They occur in such localities as suggest their
crystallization from mineral matter in the condition of vapor. They oc-
cur in fissures and upon points particularly exposed to the slow circling
atmosphere of the cave. They are also entirely without anything like
stalactitic surface or marks of water. Many of them are as delicate as the
frost gathering about the mouth of a well in winter.
Another problematic form has been called mineral cotton which seems
to be pushed out from the rock and is said to be in places 18 inches in
length and have a uniform diameter as fine as a hair. One cluster of this
formation has been significantly called “Noah's Beard.” Crystals of
gypsum occur in the clay, in some parts of the cave.
Another remarkable feature of these large caves in the Black Hills is
the entire absence of sink-holes, upon the surface above them. One looks
in vain to see upon the surface signs of drainage down into the cavern
below. The sink-holes, which doubtless formerly existed, have been
filled by the deposition, on a grand scale, of drift material, in broad ter-
races, probably by streams during the Pleistocene. In the upper cham-
bers of the Wind Cave this filling of the sink-holes by bowlders and clay
from the interior of the Hills is quite evident. Some of the chambers
have a rough roof in the form of an inverted cone, with erratic pebbles
and boulders cemented together with calcareous material. In other
places boulders, granite and quartzite like those now occurring upon the
surface, are found at lower levels in passages leading from the upper
chambers. It seems therefore evident that these caverns are very ancient
and that they were mainly formed previous to the distribution of pebbles
and boulders from the Hills over the surrounding region. The Wind
Cave is about 12 miles north of Hot Springs.
ONYX CAVE.
The Onyx Cave is about six miles above Hot Springs, up one of the
branches of Fall river. This cave has recently been discovered and has
derived its name from a deposit said to be quite abundant, resembling the
Mexican Onyx. Quite handsome agates were shown me from a rock in
the vicinity of the cave.
It seems not improbable that caves of similar interest and magnitude
may be found at other points in the Carboniferous rocks belting the
Hills,
GEOLOGY OF SOUTH DAKOTA. 51
#
FURTEIFR, NOTES UPON THE CARBONIFEROUS.
From personal examination of the Carboniferous rocks more with refer-
ence to their fossils than to make out a careful section, which has already
been well done by Newton, the following notes have been made: A fos-
sil which very frequently occur in tha Carboniferous is a species of Syrin-
gopora, Fusilina cylindrica, which resembles wheat grains, occurs in abun-
dance in the alternating series. In the boxwork of Wind Cave some very
interesting fossils are beautifully preserved. That is, they are sus-
pended in the open meshes of the hoxwork and coated with crystals simi-
lar to those upon the boxwork. Some of these are long and slender like
reeds or slender algae. They uniformly lie horizontal or parallel with the
original embedding strata. Some attain a length of nearly a foot with
a diameter of less than a quarter of an inch. Some of the shells resem-
bling Euomphalus and Pleurotomaria, with a diameter of from 2 to 3
inches, were preserved in a similar way. Others preserved in this way
were horn-shaped corals 5 or 6 inches in length, and shells resembling
Chonetes about 2 inches in width.
The silicious limestone not only abounds, as Newton remarks, in layers
of chert of irregular form but also large silicious concretions of a very
symmetrical oblate spherical form often attaining a diameter of from 1;
to three feet. These are very abundant in the drift about Wind Cave
and Hot Springs, and seem to be a general feature of this limestone, on all
sides of the Hills. They were observed at regular intervals in horizontal
rows, in the limestone west of Tilford. Specimens of Lithostrotion were
also observed. The Carboniferous rocks, west and northwest of Tilford,
contain large masses of green porphyry or trachyte which have been in-
fused into it in huge lenticular masses and in dikes.
TIIB, EXTENT OF THE CARIBONIFEROUS.
As has already been stated, the Carboniferous formations are confined
to the interior of the Black Hills, but a more detailed description may be
helpful. \
The geographical areas in which the Carboniferous rocks are exposed
lie in an irregular ring-like formation around the Archean center of the
Hills, and their exterior boundary is overlaid by the Red Beds of the
Trias. Most of the Paleozoic area, marked upon the map, is Carbonifer-
ous and additional areas, not represented, are found along the eastern
side of the ring. Between Rapid Creek and Spring Creek along the di-
vide, Carboniferous rocks extend five or six miles west of their eastern
limit. The Carboniferous rocks have had an important influence upon
the topography, to which reference has already been made in a general
way. The Carboniferous limestones are perhaps the most durable rock
\
52 GEOLOGY OF SOUTH DAKOTA.
---
in the Hills. They still overlie the western portion of the Black Hills
uplift. From the north, west and south, this plateau rises gradually as one
approaches the interior of the Hills, while on the east it has an abrupt
escarpment overlooking the Archean erea. It has a width east and west
of from 15 to 20 miles and a length north and south of 60 miles. Its sur-
face is generally smooth or gently undulating, and is sharply cut by
streams, with deep and steep-sided canyons. Newton remarks that,
considered in its total mass, it is the greatest elevation of the Hills, and
bears upon its broad back a crag, which is second to but one other in
height. Crook Tower has an elevation above the sea of 7,320 feet and
is only 80 feet lower than Harney Peak. It rises 200 feet over the level
of the adjacent parts of the plateau. The height of this table land
above the sea is about 7,000 feet. The Carboniferous strata, on the east-
ern margin of the Hills, are comparatively small in extent and dip every-
where rapidly toward the east. They constitute a monoclinal curve
around the edge of the Archean. In the northern third of the Hills, the
Carboniferous rocks are locally disturbed by eruptions of later igneous
rocks. Like the Potsdam sandstone in the vicinity of the outflows, they
are sometimes nearly vertical.
THE SEPARATION OF THE CARBONIFEROUS AND RED J3]EDS.
The upper limit of the Carboniferous is not as easily determined as the
lower. Newton places it above the variegated sandstone becausé he
found a few fossils, supposed to be Carboniferous, in some of the strata,
just below that horizon. In this he differs from Dr. Hayden and Prof.
N. H. Winchell. Dr. Hayden labored under the disadvantage of a hasty
reconnaisance under circumstances of danger from the Indians. He failed
to comprehend the thickness of the Carboniferous. He divided the Car-
boniferous into two portions, as follows:
G. Hard, more or less gritty, yellowish and whitish lime-
stone, containing Productus, Spirifera, Euomphalus,
etc., passing down into a light yellowish calcareous
grit, altogether -------------------------------- 50 feet
H. Very hard gray reddish limestone, containing Syring-
opora, Productºs, Terebratula, etc - - - - - - - - - - - - - - - - 50 feet
Newton recognized in his G, No. 3 and in H, No. 2. The upper mem-
bers, therefore, of the Carboniferous were included by Hayden in his Red
Bed series. (Trans. Am. Phil. Soc., 1862, teste, Geol. Black Hills, p. 113.)
Prof. Winchell, on the contrary, extends the Carboniferous upward, with
much doubt, however, so as to include not only the formations recognized
by Newton, but also 100 feet of red clay and 30 or 40 feet of purple lime-
stone which seem properly to belong to the Red Bed series. The ob-
GEOLOGY OF SOUTH DAKOTA. * 53
&
scurity of this separation will appear by comparison of a few representa-
tive sections given by Newton. At the head of Minnekahta creek or Fall
river, the following section was recorded: (Geol. Black Hills, p. 121.)
RED BEDS— ? f
9. Purple limestone------------------------------- 4 feet
8. Red clay in places soft red sandstone-------------- 140 feet
CARBONIFEROUS— t t
7. (No. 5) A colored sandstone, red, yellow, pink, etc., with
calcareous layers and limestone - - - - - - - - - - - - - - - - - - - 285 feet
6. A layer of black sandy carbonceous shale- - - - - - - - - thin
5. Sandstone ------------------------------------- 3 feet
4. A layer like 6---------------------------------- 1 foot
8. Sandstone, red and yellow - - - - - - - - - - - - - - - - - - - - - - - 25 feet
2. Silicious and argillaceous limestone with nodules of
flint------------------------------------------ 20 feet
1. Limestone, silicious, weathering irregularly caveruous,
outcropping just at the level of the creek, probably
No. 8 of the Carboniferous section - - - - - - - - - - - - - - - - - - - - - - -
Near the head of Amphibious or Beaver Creek the following: (Geol.
Black Hills, p. 122.)
RED BEDs—
7. Purple limestone ------------------------------- 25 feet
6. Red clay, somewhat soft red sandstone- - - - - - - - - - - - - 100 feet
CARBONIFEROUS—
5. Variegated sandstone, blended with red, yellow and
white-----------------------------------------100 feet
4. Alternating limestones, calcareous sandstones, yellow,
reddish, white and pink, near base a stratum of deep
red, calcareous sandstone, 10 feet-- - - - - - - - - - - - - - - -200 feet
8. Limestone, silicious, containing much flint, has a
tº. brachiated appearance-------------- - - - - - - - - - - - - -250 feet
2. Limestone, white or gray -- - - - - - - - - - - - - - - - - - - - - - 180 feet
1. Limestone, pink, impure and siliceous, containing frag-
ments of crinoids exposed.-------------- - - - - - - - - - - 20 feet
The following section on Box Elder is somewhat abridged from New-
ton's description: (Geol. Black Hills, p. 126.)
RED BEDS—
14. Purple limestone------------------------------- 25 feet
13. Red clay-------------------------------------- 100 feet
54 GEOLOGY OF SOUTH DAKOTA.
{
CARBONIFEROUS—
12. Variegated sandstone, white and yellowish below.-- 90 feet
11. Slope----------------------------------------- 10 feet
10. Sandstone, red with calcareous layers - - - - - - - - - - - - - - 60 feet
9. Slope ----------------------------------------- 14 feet
8. Limestone, pink -------------------------------- 1 foot
7. Slope ----------------------------------------- 10 feet
6. Purple limestone, alternating with pink and white,
soft, thin bedded sandstone -- - - - - - - - - - - - - - - - - - - - - - 15 feet
5. Slope ---------------------------------------- 5 feet
4. Limestone, gray and pink, stained with red, alterna-
ting with layers of pink and reddish sandstone- - - - - - 105 feet
3, Slope----------------------------------------- 6 feet
2. Limestone, gray, compacted, fossilerous----------- 8 feet
1. Flinty limestone, with occasional layers of pink and
yellow, thin gray sandstone, which weathers red-- - - - 146 feet
Near Black Butte, in the northwertern portion of the Hills, resting on
the volcanic rock of the peak, fragments of the metamorphosed Potsdam
are seen, and upon them in regular order the strata, given in the follow-
ing section: (Geol. Black Hills, p. 128).
RED BEDs—
5. Purple limestone ------------------------------- 25 feet
4. Crumbling soft red sandstone- - - - - - - - - - - - - - - - - - - - - 100 feet
CARBONIFEROUS—
3. White, yellow, orange, and dark red, massive, soft
sandstone, irregular in color weathering in fantastic
shapes ----------------------------------------880 feet
2. Talus -----------------------------------------200 feet
1. Silicious limestone to the bed of the creek - - - - - - - - - - feet
Other sections given with greater detail are found in Newton's Re-
port. They differ but slightly in general character from those already
presented. They all show how, instead of a well marked horizon, there
is a general transition from the Carboniferous sandstone into a sandstone
or clay of the Red Beds. Even those which are recognized as Carbonif.
erous begin to show the deep red color of the Red Beds in an irregular
Iſla, IllſleT.
CHAPTER VI.
THE MESOZOIC FORMATIONS.
These comprise the most of the surface of our State and are commonly
arranged under the following systems: Triassic, named from the three-fold
division of the formation in Europe; Jurassic, named from its prominence in
the Jura mountains in Switzerland; and the Cretaceous, (creta, chalk)
named from the prominence of chalk in the European beds, as for example
in southern England and northern France. All the formations are usually
but imperfectly consolidated. They are mostly sandstones, clays and
marls.
;
THE TRIASSIC OR RED BEDS.
These like the Paleozoic formation are confined to the interior of the
Black Hills, where they occupy a ring-like area surrounding the Hills.
They are particularly conspicuous in the topography because of the easy
erosion of the clays. As a result we have the Red Valley and a ridge
within formed by the harder purple limestone.
The Red Beds consist of the following members in descending order:
3. Deep red clay, sometimes becoming soft, shaly,
argillaceous sandstone containing large quantities
of gypsum -------------------------------.200–250 feet.
2. Pinkish, purple and argillaceous limestone - - - - 15–40 feet.
1. Deep red clay, sometimes becoming soft argil-
laceous sandstone containing but little gypsum -- 75–100 feet.
These three formations may conveniently be called: Lower Red Beds,
Purple Limestones and the Upper Red Beds. They may be conform-
able to one another and to the underlying Carboniferous rocks, and yet.
because of their structure and irregularities, this conclusion can hardly be
demonstrated.
TII R. T.OWER RED BEDS.
This formation consists mostly of red clay, which is more arenaceous
toward the north end of the Hills and about Bear Butte. It is entirely
without fossils and rarely shows traces of stratification. It varies much in
thickness. The Purple limestone sometimes comes almost in contact with
56 GEOLOGY OF SOUTH DAKOTA.
f
the Carboniferous sandstone, but in no case is it more than 100 feet above
it. Traces of gypsum are sometimes observed in this formation. This is
more frequent in the southern part of the Hills. Where the Carbonifer-
ous Limestone is prominent or where the outflows of porphyry occur the
Lower Red Beds seem less likely to be brought out by erosion. Prof.
Winchell, in his trip through the northern portion of the Hills, for this
reason greatly underrates the thickness of these lower beds. The color
of the clay is bright red, the cause of which we will speak of more at
length further on.
THE PURPLE TIMESTONE.
This formation is a very conspicuous and constant feature of the Trias-
sic. It very generally forms the inner slope of the Red Valley, though
sometimes it is separated from the hills within by another valley caused
by the Lower Red Beds. As one enters the Red Valley from the outside,
the inner side appears to rise in gentle, dome-like undulations, remind-
ing one of the contours of the hills of Loess, in Nebraska and Iowa.
The surface is largely without trees and covered with grass. As he ap-
proaches he is surprised that the whole surface is an almost continuous
rock pavement, the strata dipping in all directions parallel with the pres-
ent surface. Another feature impresses him also, namely: the infrequency
of ravines or cliffs. These rarely occur except where streams of consider-
able size have cut their way through the limestone into the Red Valley.
This they do by regular V-shaped gaps, whose points are scarcely
wider than the present streams. These characters are very striking and
are rarely seen in other formations. The impression at the first view is of
a formation of immense thickness, and so it seems to have been estimated
by Prof. Winchell, who makes it nearly 100 feet. (Black Hills of Dak.,
Ludlow). Wherever it is broken, it displays a very uniform thickness,
from 25 to 40 feet. The limestone consists of thin strata of a grayish,
pink or purple, somewhat mottled and often deeply stained by red, per-
haps from the overlying clay. According to Dr. Ricketts, of Newton's
survey, it consists essentially of carbonate of lime with traces of silicate
of alumina and iron, and has an odor, when ground, like Canada
petroleum. This odor is discernible when the rock is crushed and on
fresh fracture. Prof. Carpenter gives several careful analyses made by
Profs. Jansen and Headden, of the Dakota School of Mines, which shows
that it is unusually pure carbonate of lime. (Geol. and Min. Res. Black
Hills, p. 43). In the pure varieties nearly 99 per cent. was ealeium car-
bonate. The most impure was 91 per cent. Not only is the rock thin
bedded, but it is divided upon the surface into polygonal blocks,
which are slightly concave or saucer shaped, above. This feature,
GEOLOGY OF SOUTH DAKOTA. * 57
Prof. Crosby suggests, indicates its deposition in marshy lake beds, which
were frequently dried up. He attributes this concave feature to an action
similar to that forming mud-cracks. (Proc. Port. Soc. Nat. His, Vol.
XXIII., p. 509). Dr. Carpenter shows, however, that this feature is con-
fined to the present surface and is due rather to the warping influence of
weathering at the present time. (Geol. and Min. Res., Black Hills, p. 44.)
Prof. Newton speaks of the crumpled character of the beds as follows:
“Underlaid by 75 to 100 feet and overlaid by 200 feet of soft red clay,
the limestone rests between two cushions, so that in the uplifting of the
rocks at the time of the elevation of the mountains, it was not shattered
and dislocated so extensively as if it had been inclosed between Inore
rigid strata. It is found bending and warping suddenly, especially about
some of the volcanic peaks, and conforming to all the little irregularities
of the outer slope of the hills without exhibiting any great fractures or
dislocations. Though it is usually more fragmentary in its structure, filled
with cracks and joints perpendicular to its bedding, they seem rather due
to its composition and mode of weathering than to the bend of the strata.”
This rock appears quite soluble in water, for many of the springs that flow
from its base precipitates large quantities of calcareous tufa. Copious
springs are found issuing from this limestone in the Red Valley, north of
Rapid City, especially in the vicinity of Piedmont and Tilford.
This peculiar dome-shaped folding of the limestone has not yet been
satisfactorily explained, and facts are not yet collected sufficient to
justify a confident conclusion. But one significant fact may suggest a
possible explanation. The deposition of gypsum and the occurrence of
the deep red color correspond with the conditions favorable to the rapid
evaporation of water and the deposition of salt. It is reported that salt
springs are found upon the western slope of the Black Hills, but thus far
no trace of salt has been found upon the eastern side. May it not be pos-
sible that the lower Red Beds, and possibly the upper, at one time contained
masses of rock salt, not of uniform thickness, but deposited in irregular
beds somewhat as the gypsum is now. Then suppose that in the process
of elevation and subterranean drainage of the Hills these masses have dis-
solved out, causing an irregular thining of the Red Beds. This would
have left the Purple Limestone with an attitude similar to that which it
now has. The color of the Purple Limestone seems due to the small pro-
portion of iron oxide which in the analysis of Prof. Jansen, already re-
ferred to, amounted to 37-100 of 1 per cent. This Purple Limestone re-
ceives a fine polish and has been called marble. Its use for this purpose
may at some time be important. . No trace of fossils are found in this
limestone. The report to that effect by Dr. Hayden seems sufficiently
disproved by both the observations of Newton and Carpenter, who broke
to pieces tons of rocks in search of fossils. Dr. Carpenter informs me
that he found not the slightest trace, except a wing of an insect.
\
58 GEOILOGY OF SOUTH DAKOTA.
;
THE UPPER. RED BEDS.
These resemble closely the Lower in composition and appearance, but
are two or three times as thick. They are also arenacous in places where
the Lower show that character. They abound in deposits of gypsum,
which lies in knobs and cliffs in the valley partially buried in red clay.
Gypsum occurs both in thin layers and of snowy whiteness and in irregu-
lar masses blotched with gray. The layers are lenticular in form and lie
at different angles of inclination. They vary from one-half inch to 10 or
even 25 feet in thickness. It is possible that excavation may reveal
greater masses. At Hot Springs, at the Cement Works, 2 or 3 strata
represent a combined thickness of 35 feet. Crystals are nowhere found
abundantly, but seams of ‘fibrous gypsum or satin spar, with a thickness of
from one-half to 2 inches occur. The solution of gypsum renders the water
cathartic in its effect, although its coolness and clearness renders it other-
wise attractive. Copious springs sometimes issue from banks of gypsum.
The Upper Red Beds vary much in thickness, like the Lower.
The Purple Limestone rises in domes and gentle anticlinal folds above
the surrounding clay in the bottom of the Red Valley. This is illustrated
in sections given in Newton's Report. In the Red Valley north of Rapid
Creek a dome perhaps one-half mile in diameter rises conspicuously from
the bottom of the valley to a height of 50 feet. Near Buffalo
Gap the Purple Limestone dip sunder the west side of the valley at an
angle of 20 or 25 degrees, and rises in a prominent anticlinal ridge near
the eastern side, at the foot of the ridge formed of the Jurassic and Creta-
ceous rocks. In the pass, through which the Fall River traverses the outer
ridge of the Hills, a narrow anticlinal of the Purple Limestone shows it-
self a few feet above the waters of the stream in close contact with the
lower sandstone layers of the Cretaceous. These facts seem to favor
Prof. Winchell’s conclusion that there was a disturbance, following the
deposition of the Purple Limestone. (Black Hills of Dakota, p. 62.)
In the northern and northwestern part of the Hills, particularly west of
the line in Wyoming, the gypsum attains great prominence. It seems to
be deposited more abundantly at certain horizons, though the relation of
these to one another cannot be definitely stated. Newton says that the
first is about 75 or 100 feet above the purple limestone and the second 40
or 50 feet higher. The third is at the very summit of the red clay, and
the fourth, less persistent, is a few feet lower. In that region also sink-
holes abound, produced by the dissolving away of the gypsum below.
Cases of this sort are found in other localities more rarely. These holes
are commonly only from 2 to 5 feet in diameter, and sometimes attains a
breadth of 50 feet; and are said to have a character of sink-holes in lime-
stone countries. $
GEOLOGY OF SOUTH DAKOTA. 59
**,
THE CAUSE OF THE RED COLOR.
Newton remarks concerning this: “A large percentage of peroxide of
iron in the red beds, to which they owe their bright red color bears an in-
teresting relation to the absence of fossils. The material of which sedi-
ments are formed is derived, by the various processes of denudation, from
the rocks of older land surfaces. Whatever iron they contain is dissolved
from the land and transported in a condition of protoxide and some proto
salt, such as the carbonate, and the process is facilitated by the presence
of carbonic acid in the water. Now iron occurs in these older rocks as
protoxide and peroxide, the former of which is soluable and the latter in-
soluable in water. The peroxide, however, by the action of organic mat-
ter, such as is held in solution in boggy waters may be deprived of a
portion of its oxygen and converted into protoxide and thus be rendered
soluable. If the iron-bearing water is confined first in a shallow basin
and exposed long to the action of the atmosphere the protoxide of iron
absorbes the oxygen and is precipitated as an insoluable red peroxide of
iron. If, however, plant or animal life be present in sufficient quantities
this oxidation is prevented. In case but little foreign material, clay or sand
has been brought by the waters, the deposit will be an iron ore. In case
of large quantities of foreign material are deposited from the waters at the
same time, there will be produced, in the absence of life a brown or red
clay or sandstone and in its presence, a white or light colored formation
containing the iron as a carbonate. We reason therefore, from the con-
dition in which the iron is found in the red beds, that there could have
been little or no life, animal vegetable, in the water from which it was
deposited. The conclusion is strengthened by the fact of the large quan-
tities of gypsum which is usually derived from the evaporation of saline
waters. The degree of saline concentration which the precipitation of
gypsum indicates, would be highly inimical to life. The presence of
gypsum helps to account for the absence of life and the absence of life
accounts for the brilliant color. The three prominent characteristics of
the formation (that is the red beds) are therefore quite in harmony with
each other.” (Geol. Blk. Hills, p. 138.)
Accepting this explanation of the striking red color the question re-
mains, as to how these circumstances, favorable for its formation, were
produced.
This red color is quite common in the whole Rocky Mountain region,
not only on the eastern slope of the mountains, but to the various de-
tached members of the system. We must, therefore, look for some ex-
tensive condition. If we seek some case in the present, parallel to the
one already indicated, we perhaps can find none better than one on the
eastern shore of the Caspian sea, where, because of dry climate and the
shallow waters, the of deposition of gypsum and salt is now going on.
In the gulf known as the Kara Boghaz, which is separated from the
Caspian by a narrow strait, the evaporation is so rapid as to produce an
almost constant flow from the sea into it. This strait and this gulf give
the impression to an unlearned observer that there must be a mysterious
60 GEOLOGY OF SOUTH DAKOTA. f
subterranean outlet. The water flows in, carrying with it the salt and
other soluble minerals. It then evaporates, leaving the salt and minerals
behind. We have already noted that the Triassic formations do not ap-
pear along the Eastern side of the Mississippi Valley, nor anywhere
further east than the Black Hills, with a possible exception of an
area in rorth central Iowa, about Fort Dodge. In the eastern part
of the United States, on the Atlantic slope, beds referred to this
age are found in Connecticut, New Jersey and further South. There
they seem to have been attended with volcanic outflows, and
there are signs of a high elevation of the whole eastern half of
the continent. This may have been sufficient to reduce the extent of
the sea east of the Rocky Mountains to a long, narrow gulf of salt water,
connecting with the pen sea. This may have been subject to a dry cli-
mate, resembling that of central Asia, and in this way we account for
the peculiar characteristic of this formation. Prof. Carpenter suggests
(Gold & Min. Res., Black Hills, p. 51) that perhaps the effect of the
“Appalachian revolution,” which raised the Appalachian Mountains, was
to close the southern opening of the Mediterranean, then existing be-
tween the eastern and western parts of the continent, causing it to be-
come gradually so salt from evaporation, that save, perhaps, in estuaries
surrounding this border, all life perished. He says the presence of lime-
stone, in the clay, would seem to militate against this view, but
the structure of this limestone has none of the characteristics of an or-
ganic limestone. It may be a chemical precipitate.
The evidence that these strata are Triassic consists of their stratigraph-
ical position, and the fact that some beds, resembling them further west,
have been shown to have fossils belonging to that age. Because of the
doubt still lingering, the term Red Beds is more frequently used than
the term Triassic, which would indicate a definite conclusion concerning
their age.
THE JURASSIC FORMATION.
The Jurassic System, which is so largely developed in Europe, is noted
not only for its remains of huge swimming and flying reptiles, but
also for its large deposits of iron ore. For a long time it was thought
to be absent from American geology. In the Eastern States red
and brown sandstones were found, which were thought to cor-
respond to this age, but were finally determined to be Triassic. The
first discovery of the existence of the Jurassic in the west was made by
Prof. Meek, from fossils collected in the Black Hills by Prof. Hayden in
1857. The discovery was announced in the proceedings of the Academy
of Natural Sciences of Philadelphia in March, 1858. Since that announce-
ment the formation has been found to be generally present in the Rocky
GEOLOGY OF SOUTH DAKOTA. 61
\
Mountain system from the extreme north to New Mexico, and from their
eastern slope westward to the Wasatch Mountain. Perhaps no locality is
better furnished with fossils than the Black Hills. The Jurassic rocks of
the Black Hills occur in a narrow strip bounding the outside of the Red
Valley, and like it forming a complete ring the Hills. Their exposure is
not wide, because of their easy erosion and their being surmounted by a
hard capping of Cretaceous rocks which covers them. The formation is
distinguished from the Triassic, or Red Beds, most easily by a difference
in color. The Red Beds gradually become more arenaceous while their
color changes abruptly from a deep red to a white, yellow or gray. The
thickness of the formation about the Hills is from 200 to 300 feet. They
are little more than 200 in the southern portion of the Hills, and thicken
to 400 at the north end, and 600 northwest along the Belle Fourche, in
northeastern Wyoming. -
y THE CHAIRACTER OF THE BEL).S.
We will first give a few characteristic sections from different parts of
the Hills, as reported by Prof. Newton and others.
Near Camp Jenney on the northern side of the pass through which
Beaver Creek flows the following section is noted: (Geol. Black Hills,
p. 157.)
CRETACEOUs, No. 1.—
6. Sandstone yellow and white, somewhat lamellar and
containing ripple-marked surfaces. - - - - - - - - - - - - - - - - 50 feet
5. Sandstones, yellowish with red stains, heavily bedded, 40 feet
4. Sandstone, very white, fine grains and massive, easily
decomposed into fine white sand, forming a well marked
cliff, with caverns and holes - - - - - - - - - - - - - - - - - - - - - - 100 feet
JURASSIC–
3. Covered by talus and not well exposed; at intervals,
outcrops the gray or greenish clays or marls, with oc-
casional beds of limestone with fossils, also some sand-
stone -----------------------------------------
2. Maris or clays, gray and purple, with nodules of im-
pure limestone; base covered - - - - - - - - - - - - - - - - - - - - - 110 feet
1. Similar to the last, containing fossils to base of cliff-- 20 feet
This reaches nearly to the base of the Jurassic.
At Buffalo Gap is the following section: (Geol. Black Hilis p. 158.)
CRETACEous, (395 feet exposed—)
16. Sandstone, capping hill; massive, white, stained, yel-
lowish and reddish - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -300 feet
15. Unexposed ------------------------------ - - - - - 25 feet
14. Sandstone soft and massive, pinkish in color - - - - - - - - 70 feet
62 GEOLOGY OF SOUTH DAKOTA.
JURASSIC–(234) {
13. Mostly concealed, but white or reddish, soft argilla-
ceous sandstone below - - - - - - - - - - - - - - - - - - - - - - - - - - - 105 feet
12. Sandstone, light red, almost sand - - - - - - - - - - - - - - - - - - 55 feet
11. Sandstone, greenish and calcereous, thinly bedded - - - 20 feet
10, Sandstone, white or greenish, in thin layers, with
many ripple-marks ------------------------------ 20 feet
9. Shale, red and gray and shaly sandstone - - - - - - - - - - - - 8 feet
8. Shale, red and gray ----------------------------- 5 feet
7. Sandstone, red and pink, soft below, hard above, with
ripple-marks ---------------------------------- 8 feet
6. Sandstone, yellowish, greenish, reddish and thin brac-
ciated bend ------------------------------------ 10 feet
5. Sandstone, white --------------------- - - - - - - - - - 3 feet
RED BEDs—(255 feet exposed)
4. Clay, deep red --------------------------------- 50 feet
3. Gypsum--------------------------------------- 10 feet
2. Clay red, with gypsum - - - - - - - - - - - - - - - - - - - - - - - - - - 175 feet
1. Limestone, pink or purple -- - - - - - - - - - - - - - - - - - - - - - - 10 feet
At the north end of the Hills, on Red Water creek, near the west
boundary of the State, Mr. W. F. Patrick, observed the following section:
(Geol. Black Hills, p. 162)
JURAssIC—(410 feet exposed)
\
10. Clay, gray, white and purple, capping the bluff - - - - - 35 feet
9. Sandstone, lamelear and yellow, uppers layers hard
and brown------------------------------------- 30 feet
8. Sands, argillacous, yellow and greenish with layers of
calcareous sandstone filled with fossils, Ammonites,
Belemnites, etc. -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 35 feet
7. Sandstone, white, massive, soft - - - - - - - - - - - - - - - - - - - - 20 feet
6. Sands or sandy marls, white and calcareous with Bel-
emnites --------------------------------------- 80 feet
5. Sandstone, pinkish, passing into bed 4- - - - - - - - - - - - - 60 feet
4. Sandstone, yellow, massive - - - - - - - - - - - - - - - - - - - - - - 90 feet
3. Sandstone, lamelear and white - - - - - - - - - - - - - - - - - - - - 10 feet
2. Clay, white and gray with sandy layers -- - - - - - - - - - - 50 feet
RED BEDs— i
1. Red sandy clay with 9.YPSUlm - - - - - - - - - - - - - - - - - - - -
The following is a section taken more recently by Mr. L. F. Ward a
few miles southeast of Minnekahta in the Southern Hills. It includes a
large portion of the Cretaceous, as well as the whole of the Jurassic. He
gives it in the Journal of Geology, Vol. 2, page 255.
t
GEOLOGY OF SOUTH DAKOTA. \! iſ w; 63
{
sº §
CRETACEOUs No. 1. (275 feet) } i
13. Massive, pinkish sandstone, approaching quartzite
ocally ---------------------------------------- 75 feet
12. Greenish, white sandstone, with silicified wood and
Cyads- - -------------------------------------- 30 feet
11. Pinkish and yellowish, soft sandstone - - - - - - - - - - - - - - 75 feet
10. AClays, with indications of coal-- - - - - - - - - - - - - - - - - - - - 20 feet
9. Soft, pink and gray sandstone, with ferns and other
plants----------------------------------------- 25 feet
8. Reddish, pinkish and yellowish brown massive cross-
bedded sandstone------------------------------- 50 feet
JURASSIC. (220 feet.) §
7. Olive gray clay, sandstone shales -- - - - - - - - - - - - - - - - - 50 feet
6. Light red, soft sandstone - - - - - - - - - - - - - - - - - - - - - - - - 60 feet
5. Olive gray clays and gray sandstone shales-- - - - - - - - 40 feet
4. Olive drab clay------------------------------- 20 feet
3. Yellow sandstone shales -- - - - - - - - - - - - - - - - - - - - - - - - 20 feet
2. Olive drab clay - - - - - - ------ - - - - - - - - - - - - - - - - - - - - 30 feet
RED BEDs. (Trias.)
1. Red marls, conformably exposed at bottom of canyon - 20 feet
From these sections it will appear that the Jurassic generally consists
of gray and ash colored marls, more or less sandy limestone and soft sand-
stone, with occasional beds of green and red. The most marked single
bed is the sandstone bed 50 feet thick, usually of yellow color, but some-
times quite red. On the Belle Fourche, this bed is 100 feet above the deep
red clays, and forms the floor of a rude platform or slope on the borders of
the river. A similar stratum is found on the Red Water separated only
50 or 60 feet from the red clays below. The clays and marls do not ap-
pear to be more confined to one place than another; though they perhaps
are not so strongly developed in the extreme upper portion, as in the
lower two-thirds of the formation. They often contain seams of limestone
more or less impure; and these are possibly more common in the lower
portion of the formation. The limestones are frequently fossiferous, but
seem never to be more than a few inches in thickness, and do not consti-
tute, sofar as has been determined, continuous strata. Everywhere a large
portion is composed of sandstones, which are usually light in color, some-
times snow white. They are usually very soft or shaly passing into sandy
shales. Soft incoherent sands are also met with.
TLIE FOSSILS OF THE JUIRASSIC.
In Wyoming, along the Red Water Valley, from Warren Peak east-
ward toward Spearfish, there are found two horizons yielding fossils in
abundance; one at 135 and the other at 350 feet above the Red Beds,
64 **: ſº GEOLOGY OF SOUTH DAKOTA.
A list of the fossils found by Newton, in the Black Hills, is appended:
(Geol. Black Hills, p. 168)
Ammonites cordiformis, and A. Henryi.
Astarte fragilis, and A. inornata.
Asterias dubium. º
Avioula mucronata.
Belemnites densus. wer
Camptonectes bellistriatus, and C. extenuatus.
Dosinia jurassica.
Gervillia recta.
Grammatodon inornatus.
Lingula brevirostris.
Lioplacodus veturnus.
Myacites Nebrascensis.
Mytilus Whitei.
Neaera longirostris.
Ostea Engelmanni, and O. strigilecula.
Pecten Newberryi.
Pentacrinus asteriscus.
Pholadomya humilis.
Planorbis veturnus.
Pleuromya Newtoni.
Protocardium Shumardi.
Psammobia prematura.
Psendomonotis curta, and P. orbiculata.
Rhynconella Myrina.
Saxicava Jurassica.
Tancredia aequilateralis, T. bulbosa, corbuliformis, inomata, Postica
and Warreniana.
Thracia arcueta, and T. Sublevis.
Trapezium Bellefourchensis and T. subequalis.
Trigonia Conradi.
Unio nucalis.
Valvata scarbrida.
Viviparus Gilli.
Wolsella pertennis.
For the benefit of those who are unfamiliar with pleontology we will
say that with a few exceptions they are bivalved shells similar to those
now found in the ocean, in many cases belonging to the same genera. A
few exceptions are the species of Crinoid Pentacrinus, which may be des-
cribed as a delicate flower-like starfish with a long jointed stem such as
is still found living at the bottom of the sea, and another is a species of
GEOLOGY OF SOUTH DAKOTA. 65
starfish. The Ammonites resembled the Pearly Nautilus of the present
time, except that they were larger and of a much more complicated struc-
ture. Belemnites were animals probably resembling the modern squid,
having an internal skeleton or shell, which terminated, at the posterior
end in a cylinder tapering to a point, sometimes several inches in length,
resembling in form the prong of a deer horn, or a cigar. A few resembled
the snails found in fresh water ponds. Then there were several species
of oysters, salt water mussels and salt water clams and otherforms not com-
monly familiar.
Reference was made, at the outset, to the existence of strange gigantic
reptiles in the Jurassic of Europe. Few specimen of these have been
found in this country. But one species is especially worthy of note. Not
only because it is found to be the largest land reptile ever in existence,
but because specimens of it have been found in the Black Hills. It is
called the Atlantas aurus. It is estimated, that it was nearly 80 feet in
length, of the shape of a large lizard, and its thigh bones have been
found to measure six feet in length. It is interesting to note, that dis-
tinct fragments of the skeleton of this animal have been found in a butte
near Piedmont. This was discovered and reported by Mrs. Ellerman of
that place, in 1886. The locality was visited and the choicest specimens
were taken and studied by Prof. O. C. Marsh, who is an eminent special-
ist upon vertebrate paleontology. Considering the little study which has
been spent upon the Jurassic beds, it seems not improbable that most in-
teresting and possibly new forms of the strange reptiles of that age may
yet be found in the Black Hills.
THE SEPARATION OF THE JURASSIC FROM THE CRETACEOUS.
Newton judges the Jurassic to pass conformably into the Cretaceous;
that there was no marked change in attitude of the sea bottom at the
end of the Jurassic. Both Profs. Carpenter and Crosby, however, claim
to have discovered places of unconformability indicating a distinct move-
ment of the black Hills at the end of this age. Prof. Carpenter says there
is a marked unconformability between the Jurassic and the Cretaceous
beds at the gap, at Rapid City. It was shown on the southern side of
the gap, where it had been excavated for a ditch. He found also a sim-
ilar uncomformability upon Box Elder Creek and concludes that the
Hills were uplifted and subject to erosion before the laying down of the
first Cretaceous beds. This explains why they are commonly conglome-
ritic. The end of the Jurassic was marked elsewhere by remarkable dis-
turbances of the earth's crust, particularly by the upheaval of the Sierra
Navada Mountains and the elevation of wide areas in the western
portion of our country so as to become dry land. No marked disturb-
5
66 GEOLOGY OF SOUTH DAKOTA.
ance, however, have been noted east of the Wasatch Mountains. It should
be remembered that the region must have been land during the early
Cretaceous which is not represented in our State.
f | THE CRETACEOUS FORMATION.
The members of this formation, though having many characteristics in
common, are yet quite distinct as regards their lithological character.
They are widely distributed, covering more than half of our State. We,
now for the first time in our study, pass outside of the Black Hills. It
seems that this age was characterized by a slow subsidence of the central
portion of the continent.
The Cretaceous rocks were divided by Hayden into five divisions
named successively:
1. The Dakota sandstone, from Dakota City in Nebraska where it was
first studied; ' .
2. Fort Benton clays, from its maximum development near that fort
on the upper Missouri;
3. The Niobrara, the Niobrara chalk stone, from its prominence along
the Niobrara and Missouri, near their junction;
4. Fort Pierre clays, covering the central portion of the State about
Fort Pierre; and
5. The Fox Hills sandstones, named from the range or hills on the di-
vide between the Cheyenne and Moreau rivers west of the Missouri; while
a sixth, the Laramie or Fort Union formation, now considered Cretaceous,
he placed in the Tertiary. These formations are exposed, in the order
named, as one ascends the Missouri river through our State, overlapping
one another from the north in nearly horizontal positions. From a wider
study of these formations they have been somewhat differently classified,
although these names are still used by many.
The classification given by Dr. White in the recent correlation paper
on the Cretaceous Bulletin 83, of the United States Geological Survey, is
as follows:
The Lower Cretaceous, (probably not found in our State) includes the
Potomac formation of the Atlantic slope; the Comanche formation of
Texas; the Kootonie formation of British America and the Shasta forma-
tion of northern California.
The Upper Cretaceous includes: First, the Dakota; second, the Colo-
rado, which consists of Fort Benton and Niobrara formations; third, Mon-
tana, which includes Fort Pierre and Fox Hills; while the Laramie he
consideres partly in the Cretaceous and partly in the Tertiary.
Upon our map we have followed King in our grouping of Fort Benton,
Niobrara and Fort Pierre under the Colorado, omitting the Montana and
GEOLOGY OF SOUTH DAKOTA. t 67
• *
reserving the old name Fox Hills. This seems to suit best the litholog-
ical characters of the formations in this State. The Dakota is usually
easily characterized by its abundance of grass and sandstone. Fort Ben-
ton and Fort Pierre clays resemble one another very much in appearance,
while the Niobrara is an inconstant formation, being 200 feet in thickness
in some localities while in others it is indistinguishable from the beds
above and below. We shall speak of this more particularly when con-
sidering the Colorado formation. The Fox Hills consist largely of beds
of sand and sandstones, but is of an arenaceous clayey character, between
the Colorado and the Laramie, or Lignitic. These formations are not
very distinctly marked by paleontological characters, probably differing
in life little more than can be explained by the difference of biological
conditions of the sea at different times. A synopsis of the Cretaceous
formations of our State, slightly modified from Hayden, (Geol. Black
Hills and Trans. Phil, Soc., Vol. XII, Part I) is given below.
TABLE OF CRETACEOUS GROUPS IN SOUTH DAKOTA.
No. 5. Fox HILLS GROUP.
Gray and yellowish arenaceous clays and sandstones, contain-
ing Belemnitella bulbosa, Nautilus Dekayi, Placenticeras placenta,
Scaphites Conradi, Baculites ovatus, and a great number of other
marine molluscan fossils, together with bones of Mosasaurus
Missouriensis. Localities:–Fox Hills, near Moreau river; under
the Tertiary on Sage and Bear creeks. Thickness, 100 to 150 feet.
No. 4. ForT PIERRE GROUP.
(a) Dark-gray and bluish plastic clays, containing, near the
upper part, N. Dekayi, P. Placenta, B. ovatus, Scaphites nodosus,
Dentalium gracile, Inoceramus Sagensis, etc., and bones of Mosas-
(blº’ll S.
(b) Middle zone nearly barren of fossils.
(c) Lower fossiliferous zone, containing Ammonites complexus,
B. ovatus. Heteroceras Mortoni, tortum and umbilicatum, Mosas-
durus, etc.
(d) Dark bed of very fine muctuous clay, with much carbon-
aseous matter, seams of gypsum, masses of pyrites and numerous
small fish scales. Local. filling depressions in the bed below.
LOCALITIES.–
(a) Sage creek and Cheyenne river.
(b) Fort Pierre and out to Bad Lands; also down the Mis-
souri on the high country to Great Bend and beyond,
(d) Near Bijou Hills. Thickness, 700 feet,
68 GEOLOGY OF SOUTH DAKOTA.
º
No. 3. NIOBRARA GROUP.
Lead-gray, caleareous marl, weathering to a yellowish or
whitish, chalky appearance above; containing large scales and
other remains of fishes, and many specimens of Ostrea congesta
attached to fragments of larger shells; passing down into light,
yellowish and whiteish limestone, containing great numbers of
Inoceramus problematicus, fish scales and 0strea congesta.
LOCALITIES.— *
Bluffs along the Missouri, below the Great Bend to the vicinity
of the Big Sioux river and along the latter river. Thickness,
200 feet.
No. 2. ForT BENTON GROUP.
Dark-gray, laminated clays, sometimes alternating near the
upper part with seams and layers of soft, gray and light colored
limestones, Inoceramus, four species, 0. congesta, Prionocyclas
Woolgari, Scaphites, four species, Nantilus elegans, etc.
LOCALITIES.—
About Fort Benton; along the Missiouri river, from ten miles
above James river to Big Sioux river. Thickness, 90 feet.
No. 1. DAKOTA GROUP.
Yellowish, reddish and occasionally whitish sandstone, with
alternative of dark and whitish clays; seams and beds of impure
liquite fossil wood, impressions of dicotyledonous leaves.
LOCALITIES.—
Near the mouth of the Big Sioux and thence southwest into
Kansas. Thickness, 400 feet.
THE DAKOTA FORMATION.
This is the first formation which we find exposed at both ends of the
State. It forms a prominent ridge outside of Red Valley surrounding
the Black Hills. This ridge is sometimes narrow, rising to a height of
500 to 600 feet, at other places the dip is more gentle, and the formation
produces tablelands, as at the north and south ends of Hills. Its expo-
sure about the Hills is from 3,200 to 4,000 feet above the sea, and in the
broadest portions about 10 miles wide. Prof. W. P. Jenny estimates that
its average width is about 2 miles. It is also exposed around the west
and south sides of the area occupied by the Sioux Quartzite, where the
Drift clays prevent its frequent appearance. The localities where it has
been observed are as follows: On the Firesteel, near the crossing of the
railroad, about 4 miles from Mitchell. Upon Enemy Creek southeast of
GEOILOGY OF SOUTH DAKOTA. 69
Mitchell. Only a few feet of thickness is exposed at these localities. A
more extensive exposure is found along the bank of the James river, 4 to
6 miles above Milltown. No other natural exposures are known within
the borders of our State, but the position of this formation has been very
well determined over wide areas by artesian wells. That it comes in con-
tact with the drift clays over the surface, indicated upon the geological
map, rests not only upon the facts already given but for various borings
in the Vermillion valley about Centreville and other points; it is also in-,
ferred from the position of exposures upon the Iowa side of the Big Sioux
river and the Nebraska side of the Missouri. The highest strata of sand-
stone in this formation dips below the ordinary surface of the Missouri at
Ponca Landing in Nebraska. While the same strata not only appears at
Sioux City and along the Big Sioux, at Riverside Park rising some 50 or
60 feet above the stream, but as far north as east of Elk Point, where it is
found to contain a carbonaceous stratum or impure coal a few feet above
the level of the water. This formation would be still more exposed on a
wider and more regular scale, below the drift, were it not for the ridge of
later Cretaceous clays intervening, along the east side of Brule Creek,
extending past Beresford to the vicinity of Canton. So also a similar
position is occupied by the clay forming the body of the East Coteau,
east of the Vermillion river and northwest of Sioux Falls. The effect of
these topographic features are indicated imperfectly upon the map. The
Colorado should be represented as more nearly covering the Quartzite
and Dakota in western Minnehaha and Turner counties.
The Dakota Formation averages over 350 feet in thickness around the
Black Hills, while in the eastern portion of the State it is estimated to be
nearly the same. It underlies the great plains which constitute the western
slope of the Mississippi Valley. The exposures of it are found along the
Platte River in Nebraska, a little above its mouth, and thence extending
eastward to the vicinity of Des Moines, Iowa, and northward along the
west side of the Des Moines River into Minnesota. So, also, the expos-
ures about the Black Hills are but examples of what occurs along the
foothills of the Rocky Mountains from the Canadian Line to Mexico.
TIIIE CIIAIRACTER OF THIE BETPS.
The most conspicuous feature of the Dakota formation is the abundance
of sandstone and grits. They may be grouped into from 3 to 6 different
strata of sandstone that occupy probably two thirds of the thickness of
the formation. There are separated by quite constant beds of impervious
plastic clay, usually similar to that of the Colorado group above. This
will be evident from the section of wells given further on.
10 GEOLOGY OF SOUTH DAKOTA. &
f
* ' ' ) THE EXPOSURIES AIBOUT . THE BLACK HILLS.
It is in this portion of the State that we may gain the most complete
knowledge of its formation, for its steep inclination, especially along the
east and west sides of the Hills bring out its structure most admirably.
The prominent beds of sandstones and conglomerates slope at an angle
of from 10 to 40 degrees toward the east along the side of the Hills. At
the various passes cut through the outer ridge of the Hills the streams
have dissected it in a most interesting manner. The thickness of the for-
mation at the south end of the Hills along the Red Canyon Creek, in the
plateau portion, is about 500 feet, while at the north end of the Hills it is
rarely over 200. The most complete section given by Newton is from
the west side of the Hills at Beaver Creek Gap. (Geol. Black Hills, p.
178.)
8. Sandstone ------------------------------------- 15 feet
7. Gray shale and yellow clay - - - - - - - - - - - - - - - - - - - - - -•- 15 feet
6. Sandstone with carbonaceous matter - - - - - - - - - - - - - - 10 feet
5. Gray clay or marl with nodules of impure limestone
strata with siderite, (carbonate of iron) much come in
cone and selenite------------------------------- 20 feet
4. Sandstone, gray and reddish; in places thin bedded,
with ripple marks------------------------------ 64 feet
3. Sandy shales---------------------------------...- 20 feet
2. Sandstone, whitish and yellowish, thinly bedded with
many ripple marks------------------------------ 60 feet,
1. Sandstone, at base very soft, white below and yellow-
ish above-------------------------------------- 150 feet
Other sections, giving an idea of the composition of the Dakota, have
already been recorded under the Jurassic. We will add but one detailed
section from the canyon of Fall River, southeast of Hot Springs, recorded
by Mr. L. F. Ward of the U. S. Geological Survey, in the Journal of
Geology for 1894. This is particularly valuable both for its complete-
ness, and the careful discrimination and measurement of the strata.
FORT BENTON.
11. Grayish black clays with layers of ferruginous concre-
tions extending to the south fork on the Cheyenne
River, contact conformable to the following -- - - - - - - feet
GEOLOGY OF SOUTH DAKOTA. 71
DAkoTA of NEwTo N. (339 feet.) y 'e , , , , -"
10. Pink sandstone, mostly thin bedded, with ripple marks
sº and fucoid-like impressions----------------- - - - - - - 30 feet
9. Soft black shales with traces of carbonified plant re- *
mains and some fragments of fossil wood----------- 15 feet
8. Pink and gray sandstone.------------------------ 30 feet
7. Clay, shales and sandstones, latter sometimes white,
all plant bearing much comminuted vegetable matter,
matted beds of swamp plants and well preserved di-
cotyledonous leaves of Dakota type, determinable---- 10 feet
6. Black clay, full of crabonaceous matter with locally
6 inches of impure coal-------------------------- 4 feet
5. Quarry sandstone, massive, light pink, soft, weathering
iron brown------------------------------------- 60 feet
4. Soft, yellowish and reddish sandstone--------------100 feet
3. Drab colored clays with carbonaceous vegetable mat-
ter and gypsum crystals interbedded with yellow sand-
Stones- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 30 feet
2. Soft, yellow and reddish sandstone, with some clay
layers----------------------------------------- 60 feet
JURASSIC.
1. Olive gray drab or bluish clays with reddish and yel-
lowish sandstone ------------------------------- ------------------
Near Rapid City there were found in this formation two distinct strata
of fire clay, several feet in thickness. Associated with the clay are num-
erous casts of dicotyledonous leaves.
No fossil animal remains have yet been reported from the Dakota about
the Black Hills, and such are rare in this formation everywhere. On the
other hand there are numerous traces of vegetable remains, not only the
prints of leaves, but casts of pieces of wood, and in some strata vast
quanitities of silicified trunks of trees. These are thrown over the slopes
of ravines excavated in this formation. Near Rapid City on the slope
southeast of the town, near Buffalo Gap, carloads of such material might
be gathered. So far as has been observed they seem, however, not to be
in position, but are rather of the nature of drift wood.
A point of special interest should be mentioned here, namely that nu-
merous specimens of Cycad trunks have been found at various points.
Those, which have been quite carefully studied and described by Mr. L.
F. Ward, (Journal of Geology, 1894), of the United States Geological
Survey and Prof. McBride (American Geologist, 1894), of the Iowa State
University, were collected in the Southern part of the Hills, southwest
of Minnekatha and southeast of Hot Springs. Specimens also have been
found several miles north of Rapid City, and in a ravine southwest of
that place. They all seem to be traceable to the lower layers of the
72 GEOILOGY OF SOUTH DAKOTA.
Dakota sandstone, and Mr. Ward partly for this reason strongly suspects
that the lower layers, of this so-called Dakota formation may be older
than that period. From the sandstone northwest of Mitchell, fossilwood
and numerous sharks teeth have been obtained. It may be a question
whether the stratum may not belong to the Ft. Benton.
THE DAE. OTA EXPOSURE NEAR THE EAST END OF THE STATE.
We have already stated that very incomplete exposures exist in our
State east of the Missouri. We will first give a section of the rocks ob-
tained at Sioux City. To obtain this we combine the sections given
by Prof. O. St. John in the second volume of White's report on the Geol-
ogy of Iowa, page 193, with the data derived from the artesian well
bored near by the exposure.
St. John’s section is as follows:
7. Soft yellow sandy rock with a nodular ferruginous
bands; sometimes hard shale, brown sandstone layers- 7 feet
6. Ash colored gritty clay-- - - - - - - - - - - - - - - - - - - - - - - - - 1 feet
5. Soft yellow laminated sand rock, in places tough shale,
concretionary ferrugineous rocks---- - - - - - - - - - - - - - - 2% feet
4. Blue, slightly arenaceous clays with thin nodular fer-
ruginous layers, thin carbonaceous seams sometimes
found in upper portions------------------------- 20 feet
3. Soft, yellowish laminated fined grained sandstone with
pink colored patches and rusty bands- - - - - - - - - - - - - - 12 feet
2. Tough grayish, blue shale, micaceous sandstone, finely
laminated, and inclined to a concretionary structure,
contains leaves of willow, etc., also gasteroped shells--2–4 feet
To this is added from an exposure further up the river.
1. Soft laminated ferruginous sandstone- - - - - - - - - - - - - - 10 feet
Total.------------------------------------- 46–48 ft
From the artesian well as follows: The mouth of the well is 38 feet
above the top of the sand rock or No. 7 of the section given.
1. Soil and gravel--------------------------------- 65 feet
2. Gravel ---------------------------------------- 25 feet
3. Shale ----------------------------------------- 54 feet
4. Sandstone ------------------------------------- 191 feet
5. “Chalk rock” -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -100 feet
6. Gray limestone.---------------------------------110 feet
7. Chalk rock (“probably Carboniferous”) ------------- 100 feet
These strata probably belong to the Dakota formation, as recognized
by Dr. Hayden as far down as No. 5 of the artesian section. The upper
shaly portion of it has been called Woodbury Shales by Dr.
White of the Iowa Geological Survey. The division between the Wood-
GEOLOGY OF SOUTH DAKOTA. 73
bury Shales of Dr. White and his Nishnabotna sandstone is uncertain, as
is also its relation to the Dakota Group of Hayden. The former would
probably overlap the latter 50 or 60 feet. This section would make a
probable thickness of the Dakota Formation 300 feet at this point.
Across the Big Sioux east of Elk Point is an exposure from which the
following section was taken. It is opposite the old mill site where quite
recently some excitement has been produced by the supposed discovery
of a workable bed of coal.
5. Sandstone---------------------------------- — , 45 feet
4. Lignite of variable thickness and some places quite
Ulfe –––––––––––––––– ------------------------ 3–4 inches
3. Bluish shale--------------------------------- 6-7 feet
2. Sandstone, fine grained, compact---------------- 8-10 feet
1. Shaly clay with pyrites and about four feet black
carbonaceous shale--------------------------- 10 feet
The level of the Big Sioux.
Dr. White has given the following section over a locality from a point
not far away, a little above the mouth of Broken Kettle Creek. (Geol.
of Iowa, White, Vol. 2.)
14. Light gray chalky limestone in thin shaly layers----- 10 feet
13. Unexposed------------------------------------ 47 feet
12. Yellowish shaly layers, with large concretions------ – 3 feet
11. Ferruginaous shaly layers with some bluish clay---- 10 feet
10. Soft gray and yellow laminated sandstone ---------- 25 feet
9. Blue and gray, slightly gritty shaly clay----------- 2 feet
8. Soft yellow laminated sandstone.------------------ 3; feet
7. Blue clay------------------------------------- # foot
6. Brown impure coal----------------------------- # foot
5. Bluish gray clay------------------------------- 4 feet
4. Soft yellow gray laminated sandstone -------------- 16 feet
3. Unexposed.------------------------------------ 3 feet
2. Bluish black clays, partly carbonecaous------------ 3 feet
1. Grayish clays---------------------------------- 3 feet
Total-------------------------------------------- 130 feet
Of these numbers 1 to 10 may be considered Dakota Sandstone and
number 2 is a black layer which has lately been mistaken for coal.
CO AI, OR. UIGNITE IN THE DAIX. OTA FORMATION :
Though we may speak more at length concerning the matter in our
chapter on Economic Geology; because of its bearing upon the structure
of the Dakota Formation, we will give a few brief notes at this point.
. These layers of lignite and black shaly clay have been long known in
the vicinity of Sioux City and at Ponca. At the latter place it has been
74 GEOILOGY OF SOUTH DAKOTA.
worked for a number of years, but it is considered a very inferior fuel. A
formation corresponding has been struck in a well 2 miles north of Ver-
million, at a depth of 147 feet. About Centerville a stratum of lig-
nite was struck so frequently as to give great hopes of valuable coal
deposits. But very incomplete sections were obtained from the wells.
The first vein of lignite was reported to be 3 to 3% feet in thickness, and
about 3 feet below the general upland of the valley. Another purer bed
4 feet in thickness was found several feet below. The reasons given for
abandoning the veins, were the lack of sufficient roof and the abundance
of water which flooded the shaft which was sunk. Beds of lignite have
been struck in wells north of the quartzite area; and pebbles of lignite
are thrown up sometimes in considerable numbers from deep artesian
wells.
THE DATA FROM ARTESIAN WELLS.
Since the discovery; 12 years ago, of deep artesian waters in the James
River Valley, many wells have been bored over the portion of the State
east of the Missouri river. All successful wells have entered the Dakota
sandstone, and a number of them seems to have passed through it. A
few sections will be given to indicate the general position and thickness
of the Dakota formation at these various points. They also illustrate the
structure of the Cretaceous beds of later stages overlying it.
These sections are less reliable than those already given, especially as
to the nature of the rocks, for they are given by different observers not
expert in the recognition of geological formations. These sections are
mostly taken from the Report on Irrigation of the United States Agricul-
tural Department for 1893.
PLATE III.-ARTESIAN WELL, WOONSOCIRET.

# # t
GEOLOGY OF SOUTH DAKOTA. *7t,
ſ THE YANKTON WELL (ASYLUM)
ELEVATION ABOVE THE SEA LEv EL, 1285 FEET.
- Thickness. Depth.
Yellow clay ----------------------------------------- . 25 feet 25 feet
Blue clay -------------------------------------------- 3o feet 55 feet
Chalk ----------------------------------------------- 60 feet II 5 feet
Shale ------------------------------------------- '----| 300 feet 415 feet
Sandy clay ------------------------------------------ 185 feet 6OO feet
Water-bearing sand----------------------------------- 72 feet 672 feet
Tºtal depth-----------------------------------|------------ 672 feet
THE MILL WELL (YANKTON)
ELEvATION ABOVE THE SEA LEVEL, 1190 FEET.
Thickness. Depth.
Soil, sand and gravel --------------------------------- 38 feet 38 feet
Chalk-like clays-------------------------------------- 62 feet IOO feet
Shale ----------------------------------------------- 26 feet 126 feet
Hard rock------------------------------------------- 4 feet 130 feet
Sand ------------------------------------------------ 34 feet 164 feet
Shale ----------------------------------------------- 65 feet 229 feet
Sand ------------------------------------------------ 25 feet 254 feet
Shale ----------------------------------------------- I35 feet 389 feet
Sand and clay---------------------------------------- IOO feet 489 feet
Water-bearing sand ---------------------------------- IO6 feet 595 feet
Total depth of well-----------------------------|------------ 595 feet
THE SCOTLAND WELL.
j ELEVATION ABOVE THE SEA LEVEL, 1338 FEET.
Thickness. Depth.
Soil ------------------------------------------------- 4 feet 4 feet
Drift clay, yellow above and blue below.---------------- 55 feet 59 feet
Chalk rock, white above and blue below (Niobrara)----- I2O feet 179 feet
Blue shale (Fort Benton).------------------------------ So feet 259 feet
Gray and sand rock (Fort Benton).--------------------- IOO feet 359 feet
Blue shale (Fort Benton).------------- s = * = * * * * = * * * * * * * * 40 feet 399 feet
Quicksand ------------------------------------------ 3o feet 429 feet
Blue shale------------------------------------------- 35 feet 464 feet
Quicksand ------------------------------------------ 3o feet 494 feet
lime rock------------------------------------------- I3 feet 507 feet
Water-bearing sand rock------------------------------ 28 feet 535 feet
Quartzite -------------------------------------------- 52 feet 587 feet

76 GEO-LOGY OF SOUTH DAKOTA.
A-
All between the Benton and quartzite may be considered Dakota.
THE TYNDALL WELL.
ELEvATION I,4IO FEET.
Thickness. Depth
Soil ------------------------------------------------- 4 feet 4 feet
Vellow clay------ - - - - - - - = -- - - - - - - - - - - - - - - - - - - - - - * * * 40 feet 40 feet
Blue clay---------------------------------------------------- 171 feet 215 feet
Shale--- IOO feet 315 feet
Hard rock (Niobrara)-- * * - 7 feet 322 feet
Shale (Fort Benton) ---------------------------------------- 75 feet 397 feet
Sand ---------------------------------------------------- 6O feet 457 feet
Shale------------------------------------------------ 245 feet 700 feet
Water bearing sand rock ------------------------------------ 35 feet 735 feet
“Stopped on quartzite.”
We may consider the last three strata as probably Dakota, though
much of it is shale.
THE LAYSON WELL.
EIGHT MILES SouTHwÉST OF TYNDALL. ELEvATION 1,560 FEET,
Thickness. Depth
Soil - - * * - 4- 3 feet 3 feet
Yellow clay------ º 32 feet 35 feet
Blue clay (partly drift) -------------------------------------- 55 feet 90 feet
Chalk rock -------------------------------------- (Niobrara) 286 feet 370 feet
Very hard limestone ----------------------------. - tº 2O feet 390 feet
Black clay ------------------------------------. (Fort Benton) 14 feet 4O4 feet
Yery hard stone ------------------------------ - - I foot 405 feet
Light gray clay or shale--------------------- * - 6O feet 465 feet
Soap stone----------------------------------- - - - 3OO feet 765 feet
Iron pyrites and tough clay---------------------------------. 45 feet 8IO feet
Sandstone, partly water - - (Dakota) 230 feet 1,040 feet
Coarse sand and gravel ---------------------------. * 9 3 feet I,043 feet
Hard stone----------------------------------------- we g 3 feet 1,046 feet
Black mud-----------------------------------------. e 4. 27 feet I,074 feet
Hard rock (made 1 foot and 8 inches in 3 or 4 days) ----- 2 feet 1,076 feet
GEOLOGY OF SOUTH DAKOTA.
77
THE SALEM WELL.
ELEvATION, 1517 FEET.

Chamberlain Well.—Elevation, 1547 feet.
of 716 feet and bored into it about 70 feet.
Thickness. Depth.
Soil ------------------------------------------------- 2 feet 2 feet
Drift clay, yellow above and blue below.---------------- 67 feet 69 feet
Quick sand ------------------------------------------ I I feet 8o feet
Blue clay-------------------------------------------- 85 feet 165 feet
Soap stone------------------------------------------- 40 feet 215 feet
Blue sand -----------------------, - - - - - - - - - - - ~~ (Dakota) 5 feet 22O feet
Blue shale ----------------------------------- tº wº 2 feet 222 feet
Sioux Quartzite-------------------------------------- 25 feet 247 feet
THE MITCHELL WELL.
& ELEVATION, 1316 FEET.
f Thickness. Depth.
Soil ------------------------------------------------- 2 feet 2 feet
Sandy loam------------------------------------------ 38 feet 40 feet
Blue clay-------------------------------------------- 90 feet 130 feet
White sand ------------------------------------------ 40 feet 170 feet
Blue shale ----------------------------------- (Dakota) 115 feet 285 feet
Iron pyrites and lime------------------------- * * I foot 286 feet
Sand rock, water ----------------------------- \ 29 feet 315 feet
Blue clay ------------------------------------ 34 feet 449 feet
Dry sand ------------------------------------ 3o feet 479 feet
Blue shale ----------------------------------- 5o feet 529 feet
Hard caped rock ------------------------------------- I foot 530 feet
Sand rock, water ------------------------------------- I8 feet 548 feet
THE PLANKINTON WELL,
ELEVATION, I521 FEET.
Thickness. Depth.
Black loam ------------------------------------------ 3 feet 3 feet
Yellow clay (Drift and Fort Pierre).------------------- 223 feet 226 feet
Chalk (Niobrara)------------ ------------------------- 9 feet 235 feet
Shale (Niobrara and Fort Benton) --------------------- 3O3 feet 538 feet
Sandstone, water ------------------------------------- 5 feet 543 feet
Shales -------------------------------------- (Dakota) 197 feet 740 feet
Sandstone, water ----------------------------- * * 5 feet 745 feet
Sioux Falls granite --------------------------- & º 85 feet 83o feet
Struck Dakota at a depth
78
GEOLOGY OF SOUTH DAKOTA.
T
THE IROQUOIS WELL.
ELEVATION, I403 FEET.
\
Thickness. Depth.
Blue loam ------------------------------------------- 2 feet 2 feet
Blue clay-------------------------------------------- 4o feet 442 feet
Shale------------------------------------- +-- - - - - - - - - 358 feet 4oo feet
Sand rock, light flow --------------------------------- 2 feet 402 feet
Shale ----------------------------------------------- 198 feet 6OO feet
Shale ----------------------------------------------- 248 feet 850 feet
Sand rock flow--------------------------------------- 5 feet 855 feet
Sand rock, no flow----------------------------------- 55 feet 910 feet
Soft rock, probably shale------------------------------ 190 feet I IOO feet
It is uncertain how much of this should be called Dakota, probably
that below 850.
THE HURON WELL.
ELEVATION 1,251 FEET.
Thickness. Depth.
Yellow clay.--------------------------------------- 13 feet 13 feet
Blue clay -- - 76 feet 89 feet
Gray shale- I51 feet 240 feet
Hard iron rock and sand ------- - - 9 feet 249 feet
Gray shale--------------------------------------------------- 175 feet || 424 feet
Hard sand rock----------------------------------------------- Io feet 434 feet
Shale, gray above and brown below------------------------. I 16 feet 550 feet
Conglomerate sand, shale, etc.------ 51 feet 6O I feet
Gray shale - * - - - - - - - sº * - - - - - - -> * - - IOI feet 702 feet
Brown limestone, cap rock.---------------------------------- IO feet 712 feet
White sand rock, flow--------------------------------------- 50 feet 762 feet
Hard sand rock ----------------------------------------------- Io feet 772 feet
White sand rock, flow----------------------------------------- 25 feet 837 feet
Gray lime rock,----------------------------------------------- 55 feet 892 feet
Gray shale---------------------------------------------------- 4 feet 896 feet
Gray limestone.----------------------------------------------. IO feet 906 feet
THE MILLER WELL.
ELEVATION 1,586 FEET.
Thickness. Depth.
Soil, clay and gravel---------------------------------------- 22O feet 22O feet
Blue shale-------------- 71o feet 930 feet
Hard sand rock, iron pyrites -------------------------------- 45 feet 975 feet
Shale---------------------------------------------------------- 130 feet I, IO5 feet
Hard sand rock, cap rock------------------------------------ 6 feet I, I I I feet
Sand rock-------------------- - * 5 feet I, II6 feet
Sand rock, no flow * * * * * * * * * * * * * * * * * * * * * * * * * * * * * seems º we 29 feet I, I45 feet
|
GEOLOGY OF SOUTH DAKOTA. l
79
f
{
~5
THE PIERRE well.
ELEvATION ABOUT 1450 FEET.
h
Thickness. Depth.
“Gumbo,” sandy clay and blue clay -------------------- 72 feet 72 feet
Gray shale-------------------------------------------| 20 feet 92 feet
Blue shale, hard streaks of rock ---------- ------------ 88 feet 18o feet
Black shale-----'— — — — — — — — — — — — .--- - - - - - - - - - - - - - - - - - - - - - - 70 feet 250 feet
Blue shale------------------------------------------- 70 feet 320 feet
Gray shale------------------------------- ------------ I45 feet 465 feet
Blue limestone, very hard----------------------------- ! 3 feet 468 feet
Dark gray shale-------------------------------------- 132 feet 6oo feet
Blue shale------------------------------------------- I IO feet 71o feet
Dark gray shale-------------------------------------- 160 feet 870 feet
Yellow lime rock ------------------------------------ 5 feet 875 feet
Blue shale, with streaks of sand and rock below--------- 275 feet 1,150 feet
Sand-rock, white, main flow--------------------------- 2O feet 1,17o feet
, Shale, light color------------------------------------- 22 feet 1,192 feet
Forty-two feet of this may be considered Dakota.
THE HIGHMORE WELL.
ELEvATION 1,900 FEET. HIGHEST well. IN THE COUNTRY.
Thickness. Depth.
Soil, clav and gravel- * * * * * * * * * * * * * * * - “.. •- - - -, a 240 feet 240 feet
Blue shale.---------------------------------------------------- 500 feet 740 feet
Hard gray shale and iron pyrites--------------------------- 75 feet 815 feet
Blue shale----------------------------------------------------. 271 feet 1,086 feet
Gray shale mixed with sand-------------------------------- 224 feet I,31O feet
Blue shale, capped with iron pyrites -----------------------. I2O feet I,430 feet
Sandstone, water, not flow --------------------------------- I2 feet I,442 feet
Sandy shale -------------------------------------------------- 93 feet I,535 feet
Hard sand cap rock ----------------------------------------. 2 feet I,537 feet
Soft sandstone, flow ----------------------------------------- I5 feet I,552 feet
The Dakota is penetrated here 122 feet.
80 GEOLGGY OF SOUTH DAKOTA.
t
THE HAROLD WELL.
ELEvATION I,8OO.

Thickness. Depth.
Soil, drift- - - - - 125 feet 125 feet
Blue clay- A- - - - - - - - smºs º-, * * *- - - - - I 55 feet 28o feet
Limestone---------------------------------------------------- 2 feet 282 feet
Shale, blue above and gray below, with streaks of lime- }
Stone ---- - - - - ----| 268 feet 550 feet
Black shale, sandy below - - - - - - - sº m * * - - - - - - - - - - * * *-* - - - - - - 190 feet 740 feet
Shale, gray above, blue below, with streaks of lime------ 693 feet I,433 feet
Lignite ------------------------------------------------------- , 2 feet I,435 feet
Sandstone, main flow---------------------------------------- I6 feet I,451 feet
Brown shale------------------------------------------------- 2 feet I,453 feet
Small flows at 1,000, 1,300 and 1,433 feet indicate the presence of sands
at these levels. !
AND OVER WELL.
ELEVATION I,505 FEET.
Thickness. Depth.
Soil, sand and clay------------------------------------ 45 feet 45 feet
Blue clay, drift--------------------------------------- 3o feet 75 feet
Blue shale------------------------------------------| 500 feet 575 feet
Limestone ------------------------------------------| I5 feet 590 feet
Shale, streaks of limestone---------------------------- 480 feet 1,070 feet
Sandstone, main flow--------------------------------- 5 feet 1,075 feet
GEOLOGY OF SOUTH DAKOTA. 81
t
; THE ABER DEEN WELL,
ELEVATION I,3OO FEET.

Thickness. Depth.
From No. 1, Pioneer Well—
Soil and clay----------------------------------- I6 feet 'I6 feet
Blue clay ------------------------------------- 78 feet 94 feet
Shale ----------------------------------------- 4OO feet 494 feet
Iron pyrites and shale--------------------------- IO feet 504 feet
Blue shale ------------------------------------- 375 feet 879 feet
Sand, some water ----------------------'-- - - - - - - Io feet 889 feet
From No. 3—
More sandstone -------------------------------- 22 feet 912 feet
Sandstones and lignite -------------------------- 5 feet 917 feet
To sandstone, capped rock ---------------------- 4 feet 921 feet
Sandstone, flow -------------------------------- 2O feet 941 feet
Hard shale------------------------------------- 25 feet 966 feet
Hard, fine sandstone ---------------------------- 18 feet 984 feet
Sandy shale------------------------------------ 32 feet 1,016 feet
Loose sandstone, main flow --------------------- 50 feet 1,066 feet
From a fourth well, recently completed, reported by Mr.
P. J. Stacy, beginning at 1,000 feet, below which
he found a second flow in white Sandstone -------- 5 feet I,000 feet
Blue shale ------------------------------------- 77 feet 1,077 feet
White sand-rock, third and main flow ------------ 23 feet I, Ioo feet
Conglomerate---------------------------------- 35 feet I, I 35 feet
Blue shale------------------------------------- 37 feet 1,172 feet
Pink and white shale --------------------------- 5 feet 1,177 feet
White sand-rock, no water ---------------------- 34 feet I,511 feet
“Archean” ------------------------------------ 46 feet I,257 feet
“Granite”-------------------------------------- 33 feet 1,290 feet
A specimen of granite, 4–5 inches in diameter, was submitted to me
by Mr. S. W. Narregang of Aberdeen, which is said to have come from
the bottom of well No. 4. It has every appearance of a granite boulder,
such as is found at the surface in the Drift.
Ipswich. Elevation 1531.
No record of strata given. First flow 1000, second 1230; whole depth
1230.
From these records several deductions may be drawn.
First. The Dakota Formation varies considerable in thickness, and
the line between it and the Benton cannot be drawn with confidence, be-
cause layers of sand between deposits of shale or clay seem to character.
ize its upper portion.
Second. The Dakota in its junction with the promontory of Archean
rocks runs out to a thin edge, and we may add with an irregular outline.
Third. From the wells in the latitude of Mitchell, we find that the lower
surface of the Dakota rocks dips west, from about 1300 feet above the sea,
at Salem, to 700 at Mitchell, and continues with slight declination west
6
82 GEOILOGY OF SOUTH DAKOTA. *
f
past Plankinton to Kimball. South of that line the Dakota formation
lies at a higher level, with its base from 500 to 600 feet above the
sea; but north of the latitude of Mitchell, the descent is rapid to an
altitude of between 200 and 300 feet above sea, which seems to prevail ex-
tensively to the north and northwest. This agrees well with the con-
ception that the promontory of older rocks extending from south-
western Minnesota slopes much more abruptly at the north than at the
south; and that the ocean north was a few hundred feet deeper than
the ocean at the south. No data have yet been collected to show the
depth of the Dakota formation, below the surface west of the Missouri
river, but we may presume with some confidence that it probably does
not extend much below sea level. It is known from observations south-
east of the Black Hills, that though the formation dips under the later
formation at a high angle, it in a short distance becomes nearly horizon-
tal. (Geol. Black Hills, p. 181.) g
The proposed experimental borings to be made by the General Govern-
ment will not only throw important light upon the possibilities of artesian
wells west of the Missouri, but upon the depth and thickness of this for-
mation.
Fourth. Another conclusion which seems to follow from the facts
given, is that the strata east of the Missouri have not been perceptibly
disturbed since their deposition. They everywhere show a gentle slope
which would correspond well with the natural deepening of the ocean bot-
tom. Moreover from the pressure of flows and the succession of strata it
seems that the upper strata extend further east than the lower; as would
be the case were they deposited in a gradual deepening and widening
8-9
OG 68l.j].
METHOD OF FORMATION,
It was at first apparently taken for granted that the Dakota Group
was marine. More recently an idea has been advanced that it is
non-marine. Dr. White, in his Correlation Paper on the Cretaceous,
(Bulletin 82, United States Geological Survey) takes it for granted
that such was the case. The reason, so far as given, seems to be the
following: The entire absence of marine life over large areas, and the
occasional occurrence of fresh water forms, such as the Unios and Cyrenia.
He remarks that vertebrate forms, once referred by Prof. Cope to the Da-
kota, have since been placed by him in the Jurassic. His conception of
the formation of this deposit seems to be that it was a sub-aerial formation
built up by streams upon a vast plain. He would harmonize with this
view the occasional occurrence of marine forms in the southern and
northern portions of the plains by supposing that the Dakota passed into
Y * *
; GEOLOGY OF SOUTH DAKOTA. 83
w
?.
marine equivalents both on the north and south. We are unable to fully
accept his conclusions, for the following reasons:
First. It would seem more easy to explain the occurrence of fresh
water forms in a marine formation, than the marine forms in a fresh water
formation. For, not only would fresh water forms be carried, to the sea
by streams, but if the sea advanced over fresh water formations contain-
ing such remains, they would be redeposited like marine forms. The ab-
sence of marine forms over wide areas would afford no more objection
to the marine character of this sandstone than that of many other non-fos-
silferous sandstones which are generally considered marine.
Second. This formation is conformable in many places, both below
and above, with marine deposits, the Jurassic below and the Colorado
above. Moreover beds of sand, indistinguishable from the main deposits
are found interstratified with clays and shales, containin
mains. }
g salt water re-
Third. It is difficult to account for so wide and uniform a deposit of
sand by the action of streams; while on the other hand such would be the
natural result of deposits in wide stretches of open water. The sand lay-
ers would be deposited where currents and tide action prevailed; while
the interstratified clays would be deposited in calm areas, which areas
might in turn shift so as to cover and alternate with the sand. The bor-
ing of artesian wells has brought out in a remarkable way the con-
stancy in thickness and wide extent of this feature. It seems to be
demonstrated that they continue over thousands of square miles so as to
convey subterranean waters hundreds of miles.
Fourth. We have seen that during the Triassic the region became
very dry so that the waters were concentrated. During the succeeding
age, the Jurassic, there seems to have been an inflow, not only of fresh
water from the sea, but of new forms of life. From the overlapping of
strata toward the east we cannot avoid the conclusion that during the
epoch succeeding the Dakota, the sea had advanced over the whole Dak-
ota area. Now it is commonly admitted that the advance of the shore
line is usually attended with the cutting down of the gradually cov-
ered land and the deposition of sand strata over the adjacent ocean
bottom. If the Dakota, therefore, were mainly fresh water deposits
we would still expect to find marine sand deposits upon it. This would
bring us strongly to the conclusion that the Dakota formation, so-called,
must be, at least in its upper portion, marine. The rarity of marine forms
and fossils in general, corresponds well with the supposition that the ad-
vance of the sea was so rapid as to be unfavorable to the preservation of
shells or even to the existence of life.
Prof. Lesquereanx, the eminent paleobotonist, after a study of the for-
84 GEOLOGY OF SOUTH DAKOTA.
mation and its numerous fossil plants. Cretaccous and Tertiary Flora.
(Hayden's Final Report, Vol. VIII, p. 24.)
“We may consider the formation of the Dakota Group as produced by t
a very slow, gradual, prolonged depression of the western slope of the
Continent, bringing up from the south or west the invasion of ocean
water, charged with muddy materials, periodically heaped further and
further inland by powerful tides.”
OJRIGIN OF MATER.I.A.L.
Newton assumes that the formations from the Potsdam to the end of
the Cretaceous were deposited with nearly uniform thickness over the
whole area of the Black Hills as is exhibited in Figure 1; and Jenney seems
FIGURE 1. SECTION ACROSS THE BLACK HILLS, According TO NEWTON.
I. Archean Schists and slates. 2. Granite. 3. Potsdam. 4. Carboniferous.
5. Red Beds. 6. Jura. 7. Cretaceous. 8. Tertiary. 1.
The dotted lines show amount of erosion. t
to agree with this conclusion. If this were true, the origin of the ma-
terial of the Dakota formation, as well as others mentioned, must
have been from some area beyond the limits of our Territory. In the
eastern part of Dakota the material may have been derived from the lands
on the east which are now occupied by the Sioux Quartzite and further
south by the Carboniferous limestone. This supposition is strengthened
when we discover that the highest elevation of the Dakota, in the eastern
end of our State, does not rise above 1200 or 1300 feet, while the Archean
rises even at the present time to 1500 or 1700 feet. In the Triassic age
the surfaces of these older areas were relatively much higher. Returning
to the western part of the State we notice a serious difficulty in the con-
ception of Newton. According to this no area is now known, nearer than
the Rocky Mountains, which could have furnished material for the Dakota
sandstone. Hence we find a difficulty in accounting for the thickness
and uniform distribution of the sandstone about the Hills. Other students
of the Black Hills have seen the difficulty of this view and have very gener-
ally come to a different conclusion. Winchell, after quoting Dr. Hayden,
who presents a similar view to that of Newton, says:
“On the contrary there seems to be no reason to exempt the Black Hills
from the general principles applicable to most of the mountain ranges of

GEOLOGY OF SOUTH DAKOTA. | 85
North America. That after the elevation of the granite nucleus, the :
successive sedimentary formations that surrounded it were raised by a
series of paroxysms, produced by the long continued application of a cos-
mical force. z w
“The writer sees no more reason to suppose the sedimentary strata were
until a comparatively late geological period entire and continuous over
the region of the Black Hills, than to suppose the similar granitic and
metamorphic axes of Minnesota were first covered by the continuous strata
of the Sikurian and Devonian, that bound it on both sides.”
And he mentions as a fourth prominent movement of upheaval, one oc-
curring after the Purple limestone with a large accession of dry land, par-
ticularly along the northern portion of the Hills. (Ludlow's Expedition,
f p. 65.) *
As already mentioned, Prof. Carpenter found distinct unconformability
between the Jurassic and Cretaceous near Rapid City, and concludes
there from that the Hills were uplifted and subject to erosion prior to the
lying down of the Cretaceous (Geol. and Min. Res. Black Hills, p. 46),
and has strengthened this view by calling attention to the conglomerate
character, around the Hills, of the lower beds of the Dakota and the oc-
currence of pebbles, in that stratum, which correspond in color and texture
to the Archean quartzites in the Hills; and show that they were uncov-
ered and brought within the action of the waves before the Cretaceous age
began. Prof. Crosby heartily approves this view and considers that New-
ton's theory is really inconceivable. (Proc. B. S. N. H., Vol. XXIII, p.
510). We have not the means for knowing whether the Dakota original-
ly ran out to a thin edge around the Hills, as we have found it around
the Archean in the eastern portion of the State. But the entire absence
of it inside the foothills strongly confirms such a view. If it at one time
were deposited with uniform thickness over the Carboneceous plateau of
the western side of the Hills, we can scarcely conceive of its being en-
tirely removed.
THE COLOR ADO FORMATION.
It will be remembered that we included under this head the groups
separated by Hayden, under the names of Fort Benton (or as Cope now
calls it), Benton, Niobrara and Fort Pierre, or Pierre. The character and
distribution of the separate sub-formations will be found given in the
synopsis, at the beginning of the Cretaceous. King, in his study of the
formations along the 41st Parallel, saw the justice of grouping these
three formations under one head. After he had consulted with Dr Hay-
den, the latter gave hearty indorsement to the new classification.
Later the Canadian Geologists found an ºxtensive formation in the
Valley of the Belly River, which seemed to be overlaid by a portion,
86 GEOI,OGY OF SOUTH DAKOTA.
if not the whole, of the Pierre formation. This suggested the
the separation of the Pierre from the two earlier formations. Besides
there seems to be a clearly defined break in the continuity of life forms.
In 1889, Mr. Eldrege, (American Journal of Science), of the United
States Geological Survey, proposed restricting the term Colorado to the
Benton and Niobrara, and also that the Pierre should be united with the
Fox Hills, under the name of Montana. This classification received the
full indorsement of Dr. C. A. White the veteran student of the Gretaceous
(Bulletin No. 82, United States Geol. Survey.) The reasons for
this latter classification, it is claimed, are found in the paleontology
of the strata, but it is admitted by all that it does not well corre-
spond with the lithological characters, which are most easily recognized.
King, in his first announcement, says, with much satisfaction: (Geol. of
the 40th Parallel, Systematic Geology.)
“This combination of the three areas of the old Meek and Hayden sec-
tion into a new group is rendered of value for the reason already ex-
pressed, namely: The great variableness of the areas in detail; but is
even more satisfactory in that it gathers into one member the great clay
formations of the Lower Cretaceous.
“The whole Colorado group, composed of these three areas, is bounded
on the upper surface by a heavy sandstone of the Fox Hill, and below by
a still more compact sandstone Öf the Dakota. It is essentially a great
body of shales and clays, divided in the middle by a zone of marls and
conglomerate beds. Its usual mode of weathering is to form deep troughs
directly upon the inclined Dakota.
“Whether horizontal or inclined the outcrop of the Fort Benton is
usually below the neighboring level. Directly above it the marls and
sandstones of the Niobrara group offer a great resistance to erosion and
consequently form a series of slight outcropping ridges, beyond and above
which the soft clays of the Fort Pierre again form depressions, and the
typical appearance is therefore two depressions separated by the hard
ridgy outcrops of the N iobrara.”
Not only do the Pierre and Benton closely resemble one another in
color and texture but also in the more common fossils. A mussel-like
shell called Inoceramus occurs in several species througout the Colorado;
though chiefly prominent in the Niobrara, where it is often very abund-
ant in the shaly limestone. Other genera common to the three stages
are, Ammonites, Baculites, Scaphites; while Cardium, Modiola, Tellina and
Fusus are some of the forms not only common in these strata, but contin-
uing to the present. The Benton is characterized by Prionocyclas; the
Niobrara by large species of Pinna and abundant fish teeth and scales;
and the Pierre by larger numbers of gastropod or snail-like shells.
Marine reptiles occur in. all members of this formation. Prof. Cope
says (Lectures on Paleontology,) that the Benton contains verte-
3. º
} GEO LOGY OF SOUTH DAE. OTA. 87
brate fossils, mostly of fish in poor preservation. The only reptiles
yet found are of the form of a crocodile with flat articular vertebral faces. .
The Niobrara is rich in fish remains and also in reptiles with long necks,
some resembling serpents in their long slender body. Also flying rep-
tiles with bat-like wings and long toothed jaws; birds with reptilian tails
and teeth. The Pierre formation contains Mososaurus and other sea ser-
pents with huge paddles for swimming; and Pterosaurs with bat-like
wings, and bird-like bills. Some of these winged lizards have been
found with their stretch of wing 25 feet. *
Mr. T. W. Stanton in a recent volume on the Colorado formation
(Bulletin No. 106, United States Geol. Survey) has listed about 12
species common to the Colorado and Montana groups. He also brings
out well the differences between the two faunas. sº
TTIE EXTENT OF THE FORMATION.
i
The Colorado group overlies the Dakota conformibly, around the
Black Hills, where it dips at an angle of from 15 to 30 degrees away
from them. In a short distance its beds become nearly horizontal.
Along the north branch and main portion of the Cheyenne it dips
gently northward under the Fox Hills. Along the south branch of the
Cheyenne, along the Bad river, and along the Missouri, below the latter
stream to the Niobrara, it dips southward under the Tertiary beds. It
forms the bluffs overlooking the Missouri, from near the mouth of the
Big Sioux to the mouth of the Moreau rivers. So also it forms bluffs
along the Cheyenne everywhere east of the Hills. It forms the main
body of the higher tablelands east of the Missouri; such as the Wessing-
ton Hills, Ree Hills, Bald mountains and the hills west and northwest of
Aberdeen, also the East Coteau. As the map shows it covers most of
the lower lands east of the Missouri. It is there, however, so covered with
drift, that the true nature of the “bed rock” is often unsuspected. The bluffs
near the mouth of the Vermillion river on the Nebraska side are perhaps
the finest exposure of the Benton formation in our vicinity. The Nip-
brara “chalkstone” is finely exposed in the abrupt bluffs of the Missouri,
above Yankton and, more or less, as far as Chamberlain. The top of this
formation passes below the surface of the Missouri at the Great Bend.
Quarries of the chalkstone have been opened up at various points away
from the Missouri river and natural exposures have attracted attention.
On Clay creek, north of Volin, Spirit Mound; on Brule creek, north of
Spink; northwest of Canton; 2 miles north of Brandon on the Split Rock;
at Scotland; at Rockport on the James river; Mitchell, both on the James
river, east, and on the Fire Steel, north; also west toward Mt. Vernon.
About the Black Hills, the Niobrara shows along the Cheyenne south
88 GEOLOGY OF SOUTH T) A.K.O.T.A.
of Buffalo Gap, also in the foot-hills west of the town and at numerous
points along the railroad near Buffalo Gap and Rapid City. In some
places it forms heavy limestone strata perhaps 20 feet in thickness. In
other places it seems to be reduced to a stratum of huge concretions.
East of Rapid City, it seems not to show a very hard stone, or durable
character, and appears simply as a whitening and hardening of the clays.
The Colorado Formation seems to be of quite uniform thickness where
remote from the margin. Like the Dakota, it runs out to a thin edge.
It overlaps the edges that formation generally on the east because of its
easy erosion it tends to form valleys.
The altitude of the summit of the formation may be given ap-
proximately as follows for different parts of the State: About
the Black Hills, 3,400 to 3,500 feet; between the Cheyenne and
the head of Bad River, 3,000; east bank of the Missouri, 1,900–2,000; in
East Cotean, north, 1,800–1,900; south 1,300–1,400.
Everywhere these three members are conformable, and therefore the
Pierre is always the highest and covers the lower by overlapping, except
where removed by erosion. Both the Benton and the Pierre contain
numerous deposits of iron pyrites, as has been shown in the sections of
artesian wells. This frequently gives rise to spontaneous combustion,
and produces what are sometimes thought to be volcanoes. The oxida-
tion is sufficient to start the burning of carbonaceous matter in the shales
themselves and also the organic matter surrounding. Cases of this sort
have been reported from the vicinity of Iona, in Nebraska, opposite Elk
Point, and more recently in Charles Mix county. Such phenomena were
observed by Lewis and Clark in their first trip up the Missouri.
The decomposition of pyrites produces acid waters yielding alum and
sulphuric acid, which render local areas barren of vegetation. When
this sulphuric acid comes in contact with calcareous matter it forms crys-
tals of selenite. This selenite, which is crystallized sulphate of lime, is
often mistaken for mica, which is chemically a very different mineral.
Qarbonate of iron, sometimes in strata, and sometimes in concretionary
form, occurs frequently in this formation. These layers of carbonate of
iron, by their black appearance and their occurrence in the vicinity of
the oxidation of pyrites, have strengthened the impression of igneous
action along the Missouri Bluffs at various points. Others have mistaken
these blocks of iron carbonate for coal.
These clays are usually rendered plastic by the infiltration of water
along seams and over the surface, so that land-slides often occur, some-
times upon a large scale. This fact, together with the easy erosion of the
clays, renders any close tracing of the strata practically impossible.
In addition to the sections from artesian wells, we will give the follow-
GEOLOGY OF SOUTH DAKOTA. 89
ing, illustrative of the succession of strata in the Colorado. At the pass
of the foot-hills on French Creek, Newton reports the following section
overlying the Dakota sandstone at that point: (Geol. Black Hills, p. 181)
3. Clays, yellow, somewhat arenaceous, with thin, shaly
limestone near the top, containg Inoceramºus-------- 50 feet
2. Sandstone white coarse, somewhat conglomeritic at
base------------------------------------------ 40 feet
1. Clays of the Fort Benton, dark brown or black.----- 150 feet
Nos. 2 and 3, he considered to be Niobrara, to which Prof. Winchell in
the same vicinity assigned a thickness of 150 feet, while he estimated the
Fort Pierre above it to be 250 feet. (Black Hills of Dakota, Ludlow, p. 49).
At the pass of the East Fork of Beaver Creek, which is on the west
side of the Hills, Newton obtained the following section, from a small
ridge west of the valley, and resting directly upon the Dakota sandstone.
7. Gray clay shales-------------------------------- 20 feet
6. Brown sandstone, calcareous and lamellar, with a very
fossiliferous layer containing imperfect specimens of
Ammonites, teeth of Lamna, Otodus, and other fishes 5 feet
5. Dark gray clay--------------------------------- 15 feet
4. Brown sandstone, lamellar----------------------- 4 feet
3. Dark gray clay shales--------------------------- 20 feet
2. Sandstone, like number 4------------------------ 10 feet
1. Dark gray or hlack clay, shales, with selenite and al-
kaline salts------------------------------------ 75 feet
This may be considered all Fort Benton. West of it he found frag-
mentary exposures of the gray yellowish clay of the Niobrara, and thin
overlying colored clays of the Fort Pierre, containing many Calcareous
boulders, or concretions filled with fossils.
Near the forks of the Cheyenne he found the following beds:
2. Yellow sand or aranaceous clay (possibly Fox Hills)-- 20 feet
Clay, shales, light gray, darker in streaks, within purer
limestone at base, a few limestone concretions of fossils 110 feet
1. Dark gray shale, with calcareous nodules, full of Bacu-
lites, Inoceramus, Ammonites, thickness to river----- 75 feet
1 and 2 without doubt belong to the Fort Pierre Group. This locality
was visited by the writer and the statements made by Dr. Hayden and
Newton as to its being a place wonderfully rich in fossils, was fully veri-
filed. The fossils occur in large oblate spherical concretions, having a
thickness of 1 to 3 feet and a breadth of from 3 to 5 feet. These have
been cracked vertically into polygonal columns and the cracks wholly or
partially filled with calcite of various bright colors, as yellow, brown and
red. Baculites of all sizes are found abundantly, also numerous bivalved
shells, particularly of the genera Inoceramus, and also numerous gastropod
90 GEOLOGY OF SOUTH DAKOTA.
shells, such as Fusus, Cyclonema, Fascioaria etc. These concretions lie at
irregular distances in the upper portions of the beds. Loose shells are
also found in the clays particularly Gryphea and Dentalium.
CIIALIK IN THE NIOBRAIRA.
The Niobrara not only contains a few feet of shaly limestone and light
colored clays with much calcareous matter, but also beds of true chalk,
as has been shown by a more recent microscopic study of several invest-
igators and well set forth by Prof. Calvin in his address to the Geological
Section of the American Association, at their Brooklyn Meeting, 1894.
In most text books and general writings upon the geology of the United
States, the occurrence of chalk in our country has been denied. But in
the common language of the inhabitants of the region extensive beds of
the Niobrara have been known as “chalk,” “chalk-rock ’’ and “chalk-
stone.” Distinct statements have been made by scientific men of the ex-
istance of chalk on our western plains. \
Prof. J. W. Bailey, in 1841, reports the discovery of abundant foram-
iñifera in the specimen of “prairie chalk” collected by Niccolet. So, in
1843, a similar statement was made by the distinguished microscopist,
Ehrenberg. In 1886, Prof. Marcou announced the occurrence of true
chalk in America, before the Geological Association of France, and illus-
trated his paper with traces made with pieces of chalk taken from near
Sioux City. Prof. Calvin brings out very distinctly the proof that exten-
sive beds in the Niobrara are formed of Foramenifera and Coccoliths, re-
sembling, and in some cases indistinguishable from, the corresponding
forms in the chalk of Europe.
The origin of chalk is generally considered to be from the abundant
growth of microscopic forms in a clear, shallow sea, remote from land.
The depth, in some cases, may be as great as 2,000 fathoms.
The Pierre clays are exposed generally around the Black Hills, being
overlaid by patches of Tertiary, east of the Hills, and with outliers of the
Fox Hills formation, about the head waters of Bad river and north of the
main part of the Cheyenne river. The region between the Cheyenne and
Bad rivers is largely covered, if not wholly occupied, with this formation.
East of the Missouri river, inside of the moraine, it is nearly everywhere
hidden by the drift clays.
THIE AGRICU LTURAL EFFECT OF THIE IFORT PIERR.E.
The effect of this member of the Colorado upon soils is thus expressed
by Dr. Hayden: (Trans. Am. Phil. Soc., Vol. XII., Part 1.)
“This formation is, geologically, the most important one in the Cretace-
ous system of the northwest; not only from its thickness and geographical
distribution, but also on account of its influence upon the agricultural
GEOLOGY OF SOUTH DAKOTA. \ 91
* Y ---
ſº
capacity of the country. It is only second in interest to the succeeding
bed (Fox Hill) in number, beauty, and variety of its organic remains,
commencing about 10 miles above the mouth of the James river, where
it is seen only in thin outliers capping the distant hills and bluffs, it
gradually assumes a greater thickness as we ascend the Missouri, until
we reach the great Bend, where it monopolizes the whole region, giving
to the country underlaid by it the most gloomy and sterile aspect. At the
Great Bend it attains a thickness of 200 feet, and continues to occupy the
country bordering the Missouri to the mouth of Grand river, where it
passes gradually beneath the water level of the river. These beds con-
tain great quantities of a whitish saline substance, a yellowish material
like sulphur, and an abundance of ferruginous matters, which often dis-
color the banks of the river.” p
He says further: j
“It occupies the region of White river 50 miles from its mouth, and al-
most the whole valley of the Cheyenne, excepting the source of a few of
its tributaries. It occupies an area of 200 miles in length and 100 in
width.”
He says:
“I have thus been particular in estimating its approximate limits and
extent of surface, on account of its influence on the future destiny of that
region. Where this deposit prevails it renders the country more sterile
than any other geological formation in the northwest.”
He estimates that it renders barren more than 30,000 square miles of
the valley of the Missouri. Of this about 18,000 are in our State.
The injurious effects of this formation are considerable, mainly due to
two causes: One, the soluable minerals which are popularly known as
“alkali;” the other its refractory character under cultivation, which is due
to its being quite pure clay. The alakali of which he speaks has been
analyzed, and according to Dr. Hayes of Boston, an impure specimen ob-
tained from Fort Benton, gave the following:
ANALYSIS OF “ALRALI.”
Sulphate of lime------------------------------------ 5.60 per cent
Sulphate of soda--------- -------------------------- 43.40 per cent
Sulphate of ammonia and iron - - - - - - - - - - - - - - - - - - - - - - - - - 3.25 per cent
Insoluable -----------------------------------------44.00 per cent
Moisture and loss----------------------------------- 3.75 per cent
This probably fairly represents the average composition of the material,
though it varies in different localities. With abundant moisture it seems
not injurious to vegetation; but in the later and dry portion of the sum-
mer it is concentrated so as to kill all forms of vegetable life. It rarely
is sufficiently abundant to destroy vegetation, except in low closed basins
which receive the drainage of considerable surface. When roperly uti-
lized it is not improbable that these ingredients will be found enriching
to the soil. *
92 GEOLOGY OF SOUTH DAKOTA. ~,
t
* *
The clayey character is a hindrance to cultivation in several ways. In
the spring it is soaked with moisture so as to become miry and is, not only
cold and moist at first, but later rapidly hardens and becomes packed in-
to clods. It prevents rain from entering the ground and also interferes
with the rising of moisture from porous strata which may exist lower
down. Moreover the ease with which its surface is washed away, pre-
vents accummulation of carbonaceous matter and other ingredients which
are necessary to a fertile soil. Several counteracting influences, however,
render it much less injurious than might be inferred from Dr. Hayden's
sweeping statement. It should be remembered that his judgment was
formed largely from seeing it in close vicinity to the Missouri river which
he traversed repeatedly. On uplands away from the streams the effects of
this formation are mitigated by several influences. The surface is so
nearly level that soil of considerable depth is formed. This results not
only from the repeated crops of vegetation but the mixing of siliceous
matter and silt brought by the air from sand regions surrounding it, so that
the surface has a much larger percentage of loamy material than the un-
derlying clay. Numerous burrowing animals, such as prairie-dogs, etc.,
have assisted in rendering the clays more pervious to moisture. Between
the Missouri and the Black Hills there are few places where the surface
is not covered with buffalo grass and an even larger vegetation. In the
early summer it is usually richly clothed with grass, but in the latter part
of the summer it became dried into hay, which furnishes substantial food
for the rest of the year. This thorough drying of the ground may be
considered as partly the result of the impervious character of the clay
sub-soil. The extensive cattle ranges about the Black Hills and west of
Missouri are very largely occupied by this formation and with proper
gement it might be made a most valuable pasture region.
ICl2, Ila,
TITIE FORMATION OF THE COLORAT) O BEIDS.
The occurrence of chalk throws an interesting light upon the origin of
the Colorado beds. We have concluded that the Dakota beds were
formed by the advance of the sea over the sinking land area. When the
subsidence became more gradual, and especially in areas more remote
from land, the accumulation of clays would take place in large quantities.
This would be attended by the preservation of bones and shells of ani-
mals living in the sea, also by the deposition of pyrites from the well-
known chemical reaction of decomposing animal matter and iron brought
in solution from the land. Minor oscillations of the earth’s crust would
produce local beds of sand and variations in the composition of
clays. In areas where the sediment was less abundant we should find an
abundant growth of microscopic forms as foraminifera, producing beds of
*
\
*
GEOLOGY OF SOUTH DAKOTA. 93
chalk. If this was attended with an increase of life of larger size we
would have beds of chalk limestone. Where this was not abundant
enough to produce continuous stratum it might produce patches, where
calcareous matter would be more abundant, particularly about colonies
or clusters of animals like oysters, ammonites, baculites, etc. These clus-
ters would become a nuclei for the gathering together by molecular ac-
tion of the calcareous material, mixed with clay in the vicinity, and thus
we may explain not only the occurrence of the central formation of lime-
stone, chalkstone, with its breaking up into huge calcareous concretions
at some points, but the occurrence on a smaller scale of layers of concre-
tionary masses in different portions of the Benton and Pierre members of
the Colorado formation. This explanation would carry with it also the
conception that the sea was gradually extending and deepening because
of the subsidence of the shores, especially upon the east. This process
continued from the beginning of the Dakota to the middle of the Nio-
brara formation; when a reverse movement probably began and gradually
continued throughout the remainder of this period. The distribution of
Cretaceous beds, so far as has been determined, from the fragmentary re-
mains of its strata in Iowa and Minnesota, seems to harmonize with this
theory.
THE FOX HILLS GROUP.
This formation contains many fossils similar to those found in the Pierre,
but it is quite dissimilar in its lithological character. It receives its name
from its prominence in the Fox Ridge, or Fox Hills, the conspicuous di-
vide passing west-southwest, north of the Cheyenne river. It is composed
largely of sand beds and shaly sandstone. Dr. Hayden, in his description
of it, speaks as follows: (Trans. Am. Phil. Soc., Vol. XXI., Part 1).
“In ascending the Missouri river it first makes its appearance near the
mouth of Grand river, about 150 miles above Fort Pierre. Near Butte
aux Cres (a point not certainly known) it becomes quite conspicuous, ac-
quiring a thickness of 60 to 100 feet and containing great quantities of
organic remains. Here it forms the extension that is called Fox Ridge.
The series of high hills, having a northeast-southwest course, crossing the
Missouri river at this point. In its southwestern extent, it continues for
a considerable distance nearly parallel with the Missouri, crossing the
Moreau river about 30 miles above its mouth, then forms a dividing ridge
between the Missouri and the Cheyenne, at which locality it has taken its
name. Continuing thus its southwesterly course, it crosses the Cheyenne
and is shown againin its full thickness at the heads of Opening creek and
Teton river (Badriver), forming a high ridge from which tributaries to the
Cheyenne and Teton take their rise. We thus find that this bed under-
lies an area of about 200 miles in length and 50 miles in breadth, or about
10,000 square miles.”
º
94. GEOILOGY OF SOUTH DA.K.O.T.A.
}
}
He calls attention to its very beneficial effect upon vegetation; He
says: \
“It forms a much more fertile soil, sustains a more healthy and luxur-
iant vegetation than formation No. 4, the Fort Pierre, and abounds in
springs of good water.”
The writer visited the Fox Ridge a few seasons since, and was strongly
impressed with the close resemblance of its vegetatiºn, both in the abun-
dance and species of plants, to that found in southwestern Iowa. In
fact, this formation has a similar effect upon the soil to that exercised by
the noted formation, called the Bluff Deposit or Loess, of the Mississippi
valley.
TIE ExTENT OF THIS FORMATION.
t This has already been well outlined by Dr. Hayden, but later explora-
tions have brought out additional facts concerning its distribution, par-
ticularly east of the Missouri river. Concerning its extent west of the
Missouri, it need only be added that it occurs 100 feet or more in thick-
ness in the northern part of Ziebach county, and was not seen to have
many fossils. Instead of speaking of it as a ridge running directly south-
west from near the mouth of Grand river, we should say Fox Ridge ex-
tends eastward north of the Cheyenne toward the bend in the Missouri at
Forest City. We should associate this ridge with the highland in the
eastern part of Potter county, known as Bald Mountains, whose eastern
extent reaches to Faulkton. The nature of the formation, comprising this
high land under the drift, has not been discovered, and the inference is
drawn mainly from topographic features. North from eastern Potter
county the high land extends beyond Bowdle. Upon the western slope
of this high land, particularly north and west of Swan Lake, and also in
the ridge known as Welland Buttes north of Forest City, a peculiar yel-
low loamy sand has been found which probably represents certain layers
of the Fox Hills formation. No distinct fossils have been found to sub-
stantiate the conclusion. For similar reasons this formation is believed to
underlie much of the ridge east of the Missouri in western Campbell
county and also the high land in northeastern McPherson county. These
points are represented upon the geological map, but are given as pro-
visional only.
Considering the probable orgin of the Colorado Formation and the dip
of the strata, it seems not improbable that the Fox Hills may have ex-
tended as far east as the East Coteau. The whole surface of that geo-
graphical feature is so covered with drift clays of the last geological epoch
that no red rock has been clearly identified in our State north of Dell
Rapids. Boulders, however, containing fossils of the Fox Hills Group
;
\ ! y
GEOLOGY OF SOUTH DAKOTA. \ * 95
have been found in the Des Moines valley in central Iowa. Considering
the direction of ice movement during the glacial epoch, the most easy
way of accounting for their occurrence in Iowa is by supposing that led-
ges of this formation formerly existed upon the East Coteau. Whether
or not they were wholly removed by the action of ice during the glacial
period is not yet known.
The answer to this interesting question may be found either by a bóring
upon the East Coteau, especially toward the northern end, or, possibly,
from natural exposures in some unusually deep ravines upon the sides of
this high land. The reason why Dr. Hayden considered the Fox Ridge as
extending so far northward before it approached the Missouri seems to
have been because erosion had been more active northwest of Forest City.
This has been partly the work of Virgin Creek and partly because of
local erosion which took place during the glacial period.
THE CIIARACTER OF THE FOX IIILLS.
*
This formation consists largely of gray and yellow thin-bedded sand-
stones, which sometimes weather to a pink color. With these are associ-
ated incoherent sands and arenaceous clays, the whole occupy 100-150
feet in thickness. The sandstones are rarely more than 6 inches in thick-
ness and are frequently much thinner. They attain prominence in the
topography of the country, especially in the vicinity of streams, by their
durability. They are found capping cliffs and bluffs in a very clear cut
and picturesque manner. They are cut by frequent joints, which traverse
the layers in lines usually at right angles to one another. As a result of
this, the buttes not infrequently show quite perfectly formed gable-like
summits, of which the crest is a narrow row of sandstone blocks, and the
slopes, produced by the slipping out and washing away the soft clays and
sands underneath, which are covered with a loose shingle from the cap-
ping layer. These gable summits are not infrequently extending at right
angles from the central portion of the butte.
The sandstones are frequently pierced with stems of plants standing
vertically. In certain localities some of the layers become a very com-
pact fine grained quartzite of a yellowish tint. Boulders from these
layers, or from the overlying Laramie, are strewn over much of the region
outside of the moraine and west of the Missouri river. They are usually
quite smooth, and often exhibit holes, formed by the stems of plants be-
fore mentioned.
Along the streams resting on the north slope of Fox Ridge these
harder layers form buttes upon which abundant fossils are found.
96 GEOLOGY OF SOUTH DAKOTA.
}
|
THE LARAMIE OR LIGNITIC FORMATION.
This formation has been the subject of much discussion, with reference
to its position in the geological scale. Some have claimed that it be-
longs to the Tertiary and others just as strongly that it is Cretaceous.
Some avoid the decision by calling it Post-Cretaceous; and others by
placing part of it in the Cretaceous and part in the Tertiary, like a bridge
between the well defined realms of life grouped under those names. It
lies upon the Fox Hills, conformably, but there is no marked lithological
character separating the two formations.
It obtains it name, Laramie, from its development in the vicinity of
Laramie in Wyoming, and Lignitic from its containing numerous beds of
lignite. This character, however, it is not as peculiar to this formation as
was at first thought, hence it is not as expressive of its true character.
The Fox Hills formation has been found to contain valuable beds of lig-
nite in certain localities.
* THE EXTENT OF THE LARAMIE.
Geographically its extent has been shown, so far as determined, upon
the geological map. It occupies the northwestern corner of the State
and large protions of Montana and North Dakota. Its eastern boundary
may be stated as beginning on the north line of the State about 15 miles
west of the Missouri and extending southwest to the northeast point of
Cherry creek and west to Belle Fourche. From this line it extends as a cap-
ping formation. The Fox Hills is shown underneath it in the lower val-
leys of the principal streams. Eastward it forms outliers in the shape of
conspicuous buttes as far east as the Missouri river, north of Grand
river. The buttes in Campbell county are probably capped with this
formation. From this margin as outlined in our State, it thickens toward
the north and west, its thickness culminating in Montana.
TIHIC KNTESS AND CHA RACTER OF TIIIE FORMATION.
Dr. Hayden gives the maximum thickness of this formation as 2,000
feet or more, but this thickness is probably beyond our State. Mr. Baily
Willis estimates that it may have been 1,500 feet thick in South
Dakota, originally, although the sections measured by him in his ex-
peditions between the Grand and Moreau Rivers near Rabbit Butte, gave
only half of that thickness.
Hayden gives as his characterization of the formation, that it consists
of beds of clay and sand, with rounded ferruginous concretions and nu-
merous beds and seams of local deposits of lignite. Great numbers of
dicotyledonous leaves, stems, etc., of the genera: Platanus, sycamore;
Acer, maple; Ulmus, elm, etc., with a number of large leaves of true
~ \
GEOLOGY OF SOUTH DAKOTA. 97-
palms; also land snails, fresh water snails, oysters and scales of Lepidos-
teus (gar-pikes), with bones of Trionyx (leather-backed turtle), etc.
In 1884 an expedition was sent out by the United States Geological
Survey, under the direction of Mr. Baily Willis, to examine reported finds
of lignite in the great Sioux reservation. (Lignites of Sioux Reservation,
Bulletin No. 21, United States Geol. Survey.) The area examined was about
“2,000 square miles, lying between the Grand and Moreau rivers,” in-
cluding Rabbit Butte in its western extremity and Flint Creek along its
eastern margin. The report of this region of “2,000 square miles” occu-
pies less than five pages of descriptive text. From his figured sections,
we transcribe the following sections of the Laramie strata. We combine
the sections which he has given for the following localities, in descend-
ing order: |
I. SECTION OF RABBIT BUTTE–
Top of Rabbit Butte, elevation, 2,900 feet.
Soil and sandstone -------------------------------- 26 feet
Sand and shale------------------------------------ 17 feet
Sand and sandstone ---------------------, --------- 28 feet
Shale ------------------------------------------- 3 feet
Lignite ------------------------------------------ l foot
Sandy shale -------------------------------------- 20 feet
Lignite------------------------------------------ 1 foot
Shaly sandstone------------. -- - - - - - ------------- 18 feet
Lignite -- - - - ------------------------------------ # foot
Sandy shales, with globular concretions, especially in the
upper portion-----------------------------------112 feet
Sandstone---------------------------------------- 16 feet
Conglomerate -------------------------- --------- 2% feet
Shale, with concretions--- - - - - - - - - - - - - - - - - - - - - - - - - - - 25 feet .
Sand ------------------- " " " - - - - - - - - - - - - - - - - - - - - 10 feet
Shale-------------------------------------------- 5 feet
Sand -------------------------------------------- 8 feet
Sandstone---------------------------------------- 50 feet
The level of Rabbit creek, 2,562 feet altitude.
II. SECTIOn OE BLACK HoRSE BUTTE
Top, elevation, 2,640 feet.
Sand and sandstone ------------------------------- 20 feet
Unknown ---------------------------------------- 30 feet
Sand and sandstone ------------------------------- 15 feet
Lignite ----------------------------------------- 2 feet
Shaly sandstone----------------------------------- 5 feet
Lignite ----------------------------------------- 1, feet
Sand ------------------------------------------- 5 feet
Sandy shale -------------------------------------- 24 feet
Sandstone---------------------------------------- 5 feet
Sandy shale -------------------------------------- 33 feet
98 *
GEOLOGY OF SOUTH DAKOTA.
Sand-------------------------------------------- 2 feet
Sandy shale -------------------------------------- 4 feet
Sand or sandstone------- ~r - - - - - - - - - - - - - - - - - - - - - - - - - 4 feet
Sandy shale -------------------------------------- 19 feet
Sand and sandstone-------------------------------- 41 feet
Shale - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3 feet t
* Lignite --------------------> -------------------- 1% feet
Sandy shale-------------------------------------- 9 feet
Sand and sandstone.-------------------------------- 12 feet
Base of exposure 2,404; feet.
III—SECTION ON GRAND RIVER—
Elevation of top, 2,375 feet.
Soil and sand------------------------------------- 8 feet
Sandy shale -------------------------------------- 22 feet
Sand and sandstone ------------------------------- 12 feet
Lignite ------------------------------------------ 2 feet
Sandy shale -------------------------------------- 15 feet
Sand and sandstone with conglomerate layers-- - - - - - - - - 68 feet
Lignite --------, --------------------------------- 1 foot
Sand -------------------------------------------- 7 feet
Lignite ------------------------------------------ # foot
Sand -------------------------------------------- 2 feet
Lignite ----------------------------------------- 2 feet
Sand and sandstone ------------------------------- 13 feet
Lignite, only locally developed basins in sand -- - - - - - - - 3 feet
Sand and sandstone ------------------------------- 46 feet
Base 50 feet above Grand river, 2,1684 feet.
These sections may be taken as representative of the Laramie beds.
Although horizons of lignite may be considered general, as Mr. Willis re-
marks, the beds of sandstone, shale, lignite and iron ore pass into each
other by abrupt changes in composition, He says that a bed of lignite
from two feet to two feet four inches in thickness, was entirely replaced
by nodules of iron carbonate within a distance of 300 feet on one side,
while 400 feet away on the other side it had deteriorated into a brown
clay.
We select also one of the most complete sections reported by Prof. N.
H. Winchell. (Black Hills of Dakota, Ludlow, p. 26).
Section at Ludlow's Cave, Cave Hills, Euſing County.
1. Slope, no rock seen.-------------------------10 to 15 feet
2. Silicious limestone, mostly gray and very hard,
but sometimes porous, and of a lighter color; very
rough; containing silicified wood and impressions
of bones. This rock might be styled a quartzite 1 to 2 feet
3. Whitish, Sandy marl------------------------- 50 to 60 feet
4. Reddish sandstone with many concretions - - - - - - 40 feet
5. Sandstone of Ludlow's Cave, rusty and castellated,
about ------------------------------------- 40 feet
t
{
j GEOI, OGY OF SOUTH DAKOTA. 99
6. More argillaceous and calcareous sand, white --- . 15 feet
7. Bedded blue clay (seen at a distance).---------- 35 feet
8. Unseen ----------------------------------- 85 feet
9. Lignite ----------------------------------- 56 feet
10. Massive white sandstone.--------------------------------
11. Top of Bald Butte-------------------------------------
12. Light yellowish, argillaceous marl, with ochre
concretions, about-------------------------- 35 feet
13. Carbonaceous shale, with selenite - - - - - - - - - - - - - 5 feet
14. Marbonaceous massive shale - - - - - - - - - - - - - - - - - - 4 feet
15. Hard, gritty clay, weathering bluish----------- 25 feet
16. Sandstone and sand of Wolf Butte - - - - - - - - - - - - - - - - - - - - - - -
17. White clay, (seen only at a distance) - - - - - - - - - - - - - - - - - - - - -
He says No. 2 is the source of the boulders scattered generally over
the region west of the Missouri. No. 9 has frequently been burned, pro-
ducing heat enough to bake the adjoining strata. In such cases the ap-
pearance is like that of old brick yards.
\
THE EQUIVALENTS OF THE LARAMIE.
These beds when first studied by Dr. Hayden were called Tertiary,
partly because they seemed to fill the gap between the Fox Hills and the
White River Beds, which are Miocene, and partly because the plant re-
mains found in them are closely allied to the Tertiary. He very natur-
ally assumed that these Laramie Beds represent the Eocene. The char-
acter of the vertebrate life, however, belongs to the Cretaceous. Bones
of Dinosaurs were found in some of the beds and these had no where else
been found later than Mesozoic time. The dispute is not yet settled,
though not so hotly contested as formerly. The trend of opinion seems to
be to favor a compromise of the rival claims by calling the formation Post-
Cretaceous or Transitional.
THE ORIGIN OF THIE I, AIR AMIE.
This is a fresh water formation, at least for the most part. Dr. White,
in his Correlation paper upon the Cretaceous (p, 263) says:
“The Laramie sea is understood to have occupied a very large portion of
the area, which in the immediately preceding epoch was occupied by the
marine waters, in which the Montana formation was deposited, and that
at its close the waters of the Laramie area became more or less completely
surrounded by land resulting from an elevation of sea bottom above
water level. Its waters, consequently, became partly freshened by the
surrounding surface drainage producing the habitat in which it was im-
possible for true marine forms to live but which was a congenial one for
those whose remains we find there. Thus was recorded a great physical,
as well as great biological, event in the geological history of the conti-
ment. Our estimate of the importance is enhanced, when we remember
how great was the geographical area over which it occurred.
§
:
§
;
:
100 GEOLOGY OF SOUTH DAKOTA.
§
“It is reasonable to assume that the habitat of many of the vertebrate
and other land animals, which existed within and around that area before
the event referred to occurred, was not made uncongenial by its occur-
rence. . But be that as it may, the strata, which physically constitute such
geological horizons as I have defined in this case, are the result of sedi-
mentation in great bodies of water, and physical changes which alter the
condition relating to those bodies of water and materially affected the
character of their denizens, were leading events in geological history.”
Elsewhere he remarks; (p. 152.)
“That by some persons the opinion has been held that during the Lar-
amie epoch proper, open sea waters made occasional incursions at differ-
ent places upon the area occupied by the non-marine waters, whose fauna
characterizes the Laramie formation, but although the frequent alternation
strata-bearing brackish water fossils with those bearing only fresh water
forms show that within certain districts brackish water alternated with
fresh, I have, in my extensive examination of this formation, never de-
tected any evidence of the incursion of open sea waters. Because it is
my present belief that all true marine waters were withdrawn from the in-
terior portion of this continent at the beginning of the Laramie epoch, no
true marine strata are in this memoir recognized as belonging to the Lar-
amie formation.
“While I am not prepared to admit that the open ocean made incur-
sions upon the great Laramie inland sea after it had become established as
such at the close of the Montana epoch, it is reasonable to infer that it
had somewhere a more or less restricted outlet to oceanic waters, until all
the area which it had occupied became in part dry land and in part a bed
of the great fresh water Tertiary lake or lakes, which immediately suc-
ceeded it. What we now know of the various epeirogenic (contiuent
building) movements, which resulted in the production of the present con-
tinent, leads me to believe that such an outlet, if one existed. was at the
southern end, and this suggestion is supported by certain paleonto-
logical conditions which have been observed in the Laramie strata in the
Texan and north Mexico regions. That is, certain fossil forms have been
observed in this strata which seem to indicate a greater saltness of the
water in which they were deposited than prevailed elsewhere in the Lar-
amie sea; but these observations are too incomplete to be confidently re-
lied upon in an inquiry of this kind.”
;
:
•
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;
;
:
:
i
;
CHAPTER VII.
THE CENOZOIC FORMATIONS.
Cenozoic means pertaining to recent or new life, and these formations
are so called, because the fossil forms found in them resemble quite
closely those still in existence. This is particularly true of lower forms;
the higher forms of that time long since became extinct. The Cenozoic
Eon is divided into the Tertiary and Quarternary Ages, though the ten-
dency of late has been to make the latter a subdivision of lower rank.
THE TER TIARY FORMATIONS.
The Tertiary is divided into: Eocene, Miocene, Pliocene, or “Early Re-
cent,” “Less Recent” and “More Recent.” Some include the upper part
of the Eocene and lower part of the Miocene in another group which they
call Oligocene, which means “slightly recent.” On the other hand the
Miocene and the Pliocene taken together are sometimes called Neocene
or “newer recent.”
The Tertiary Formations in our own State are now generally referred
to the Miocene. Dr. Hayden, who has studied the region more carefully
than others, although his work was published several years since, may
still be considered the principal authority on these formations. Hence be-
fore entering upon a detailed discussion we will give a synopsis pre-
sented by him, which he published in the Transactions of the American
Philosophical Society. (Vol. XII, Pt. 1, p. 105.) This is presented in
stratigraphical order and is given in his own words.
Pliocene.—Bed F.—1st. Dark gray or brown sand, loose, incoherent,
with remains of mastodon, elephant, etc. 2nd. Sand and gravel, in-
coherent, 3rd. Yellow, white grit, with many calcareous, arenaceous con-
cretions, 4th. Gray sand, with greenish tinge, contains a great part of
organic remains. 5th. Deep yellowish red, arenaceous marl. 6th. Yel-
lowish gray grit, sometimes quite calcareous, with numerous layers of
concretionary limestone from two to six inclues in thickness, containing
fresh water and land shells: Succinea, Limnea, Paludina. Helix, etc.,
perhaps all identical with living species; also much wood of coniferous
character.
Covers large areas on the Loup Fork in Nebraska, also in the Platte
Valley. Most fully developed on the Niobrara river, extending from the
102 GEO LOGY OF SOUTH DAKOTA.
d
mouth of Turtle river 300 miles up the Niobrara; also on Bijou Hills and
Madicine Hills, (S. D.). Thinly represented in the valley of the White
river, in isolated patches over large portions of Dakota Territory, west of
the Coteau des Prairies. Thickness 300 to 400 feet. (Less in South
Dakota.)
Miocene. Bed E.-Usually a coarse-grained sandstone, sometimes
heavy beded and compact; sometimes loose and incoherent; varies much
in different localities. Forms immense masses of conglomerate; also con-
tains layers of tabular limestone, with indistinct organic remains; very few
mammalian remains detected, and those in a fragmentary condition, passes
gradually into the bed below. Most fully developed along the upper
portion of the Niobrara river and in the region around Fort Laramie.
Seen also on White river and on Grindstone Hills, (S. D.) Thickness 180 .
to 300 feet.
Bed D.—A dull reddish brown indurated grit with many layers of si-
lico-calcareous concretions, sometimes forming a heavy-bedded fine-
grained sandstone; contains comparatively few organic remains. Nio-
brara and Platte rivers and in the region of Fort Laramie, also in the val-
ley of the Whiteriver. Conspiciuous and composing the main part of
the dividing ridge between White and Niobrara rivers. 350 to 400 feet.
Bed C.—Very fine yellow calcareous sand, not differing materially from
bed D, with numerous layers of concretions and rarely organic remains;
passing down into a variegated bed, consisting of alternate layers of dark
brown clay and light gray calcareous grit, forming bands, of which I
counted 27 at one locality, varying from 1 inch to 2 feet in thickness.
White River, Bear Creek, Ash Grove Spring, head of Cheyenne River.
Most conspicuous near White River and near the east base of the Black
Hills. Thickness 50 to 80 feet.
Bed B.-A deep flesh colored argillo-calcareous indurated grit. The
outside when weathered has the appearance of a plastic clay. Passes
down into a gray clay with layers of sandstone underlaid by a flesh colored
argillo-calcareous stratum, containing a profusion of mammalian and
chelonian (turtle) remains. Turtle and Oreodon Beds.
Old Woman's Creek, a fork of the Cheyenne; at the head of the South
Fork of the Cheyenne; most conspicuous on Sage Creek and Bear Creek
and at Ash Grove Spring. Well developed in numerous localities in the
Valley of the White River. Thickness, 80 to 100 feet.
Bed A.—Light gray fine sand with more or less calcareous matter pass-
ing down into an ash-colored plastic clay with large quantities of quartz
grains disseminated through it, sometimes forming aggregate masses like
quartzose sandstone cemented with plastic clay; then ash-colored clay
with a greenish tinge, underlaid at base by a light gray and ferrugineous
silicious sand and gravel, with pinkish bands. Great quantities of silica
in the form of seams, all through the beds. Titanotherium Beds.
Old Woman's Creek, also in many localities along the valley of South
Fork of the Cheyenne. Best developement on Sage and Bear Creeks.
Seen at several localities in the Valley of the White River. Thickness
80 to 100 feet.
This synopsis includes all of the Tertiary Formations, except a few
doubtfully referred to the Pliocene, mentioned further on.
GEOLOGY OF SOUTH DAKOTA. ;’
103
'Hayden at first considered the lower beds as belonging to the Eocene,
but later he classified them as stated above. He grouped the first four
beds, which he called White River, and placed the last bed in one which
he called Loup Fork Group. The latter he called Pliocene. Prof. Cope,
who, perhaps, stands first in authority because of his study of the verte-
brate remains, considers that all of the beds mentioned above are Miocene.
On the other hand, Prof. Scott, who has also spent much time in the study
of vertebrate remains, maintains that the forms of life in the White River
formation resemble those of the lower Oligocene of Europe.
THE WHITE RIVER, B.E.DS.
These are the formations which occupy the noted Bad Lands, or “Man-
vaises Terres,” between the White River and Cheyenne, southeast of the
Black Hills. They have long attracted the attention of travelers, and
have a world-wide notoriety. The surface of these Bad lands are almost
entirely barren of vegetation over extensive areas. This is due in part to
the rapid erosion and partly to the nature of the clay and absence of soil.
One approaching the Bad Lands may gradually ascend a rolling, grassy
surface, until he suddenly comes to a crest of ridge and finds himself
gazing from a height of 200 to 400 feet upon a labyrinth of winding
ravines and narrow ridges, which, in some places, widen into broad buttes
capped with tables formed by harder strata, or surmounted with slender
pinnacles, reminding one of the spires of a cathedral. At other points
the harder beds stand out as cornices and buttresses around the more
prominent buttes. While this may appear near by, further away he may
see graceful, rounded domes and ridges, which remind one of hay-stacks
or railroad embankments, where they continue as narrow ridges, with their
tops extending upon the same level for some distance. The prevalent col-
or is of an ashy gray, and in Čertain beds this is crossed by horizontal bands
of a pinkish color. As stated by Dr. Hayen, these vary in thickness from a
few inches to a few feet. From a distance they give one the impression
of beds of stone of alternate colors, but on nearer approach the color
seems not to indicate any difference in hardness, which shows it is not the
difference in erosion, but only in the color. The stack-like buttes, which
may attain a height of 50 to 100 feet, are often surrounded with very
flat, smooth surfaces, some of them bare and level as a floor, others cov-
ered with a fair growth of grass, interspersed with cactus. That which
surprises an observer is the occurrence of these perfectly barren knobs
amid the grassy flats, and again, the sudden change from a grassy flat to a
surface wholly occupied by deep ravines and sharp ridges.
The explanation of the strange phenomena just stated, seems clearly
traceable to the rapidity of erosion which results, from the clayey character
of the formations and the frequent changes of drainage. The clay prevents
104 GEOLOGY OF SOUTH DAKOTA. |
the imbibition of the water which during rains expends its whole force in
erosion, and consequently the region during the dry season is unable to
sustain vegetation. The sudden change from grassy surfaces to barren,
can be explained by the former having been formed when the base level
of drainage was at higher altitude so as to prevent the easy escape of
sediments. The clay is largely of a plastic character and yet examples
of landslides are strangely rare. Moreover the slopes of eroded surfaces
are usually very abrupt. These features may perhaps be accounted for
by the massive character of the clay and the general absence of joints
and seams which would lead the water into the interior of the mass. Be-
sides the steep slopes and ravines not only carry away the water rapidly,
so as to prevent seepage, but also quickly remove the debris of the su-
perficial slide, when it takes place. In this way the interior of the mass
is kept dry, and, as a result, the buttes stand like rock. Another peculiar
influence may also tend in the same direction. The clay, when wet,
swells and blisters up on the surface, like slacking lime. When rain
comes upon such a surface, instead of running over the outer surface, it
makes its way through the pores, produced in the way described, and
small streams and springs, already in vigorous motion, come out at the
base of the buttes. From the general impenetrability of the clay, the
water runs from the base of the abrupt slopes within a few miuutes
after the rain has begun. This causes the base to erode backward more
rapidly than the upper part of the slope, and prevents the usual gentle
slope which is found in ordinary loamy formations elsewhere. On the
western side of the Bad Lands, in the southern part of Ziebach county,
there is found what is commonly called the Great Wall, which ex-
tends from north to south for a distance of sixty miles. Its east-
ern side is generally abrupt, while the western slopes away gently toward
the valley of the Cheyenne. Only one pass, suitable for wagon road, is
found between the White river and the Cheyenne. The thickness of
the formation of the Great Basin is from 250 to 500 feet, and next to
White river, near the southeast corner of Ziebach county, the valley is
cut down nearly or quite through the White River formation to the un-
derlying the Cretaceous.
As stated by Dr. Hayden, the lower beds of the White river group
have a different color, usually purple or yellow. They also abound in
concretionary deposits of silica, which often resemble clusters of coral
of a white or delicate blue or brown tinge. In other cases the silica is
deposited in vertical seams which are from of an inch to 1 inch in thick-
ness. These are the source of the thin fragments of chalcedony, which
are scattered far and wide over the great western plains. In some cases
these concretions are of spheroidal forms reminding one of hail stones.
GEO LOGY OF SOUTH DAKOTA. ; 105
Professors Newton and Jenney record the occurrence of a bed of con-
glomerate at the base of the Tertiary, (Geol. Black Hills, pp. 30, 185,
298.) It was observed at Old Woman, Butte and near Spring creek. It
varies in thickness from 6 to 20 feet. As I found it absent in buttes
south of Rapid creek; it is probably local in development. Jenney says
“ the conglomerate is made up of small boulders, round and water-worn,
of granite, trachyte, slate, quartzite and quartz, with chert nodules from
the Carboniferous.”
The White river beds, though noted for their remarkable and abundant
vertebrate fossils are remarkably barren over wide areas. The eye roams
over thousands of square yards of gray and pink clays without the slight-
est trace of bones, shell or pebble, which if present, would be easily rec-
ognized at a distance of many rods, because of the break it would make
in the symmetrical contour of the slopes. As has been indicated by Dr.
Hayden, in his synopsis, in the upper portions of the Tertiary there are
extensive beds of conglomerate which are not often of great thickness.
Their distribution and oblique stratification suggests their marking the
former channels of rivers and currents in the lake. Lower down there
are layers of fine sandstone and sandy marl which are filled with worm
borings, and at their levels there are thin layers of sand or conglomerate
sandstone in which pebbles of clay are abundant. On exposed surfaces
these pebbles have dissolved and washed out so that the strata resembles
thin layers of scoria, the rounded openings suggesting that origin.
f FOSSII, S OF THE BAID I, A NI)S.
At other levels in restricted areas skeletons of vertebrates, large and
small, are very abundant. They are so numerous as to suggest their
having perished in droves, which may have resulted either from some severe
storm, causing them to perish from the cold, or more likely from their
having been caught upon some exposed point in the ancient lake and
overwhelmed by the rise of water attending such a storm. The bones are
rarely in a state of good preservation. They are not only broken by the
pressure of the superincumbent clay, crushing them, and by its creeping
motion separating them, but often the silica deposited in the smaller
cracks seems to have split them into fragments. This seems especially
common in the teeth and harder bones, so that although nearly all parts
of the skeleton may be found within a square rod or two, there are usually
but few pieces more than six inches in length. This is especially true of
the Titanotherium. In the Oreodon and Turtle beds firmer deposits more
frequently occur, and bones are found imbedded in the stone much as in
the case of older rocks. In some cases they seem to have served as nu-
clei for concretions. Besides the bones of animals which evidently roamed
106 A Geology of south DakotA.
t /
, upon the plains, there are also traces of squirrel-like animals which may
have been counterparts of the prairie dogs and ground squirrels of the
present time. #
Of the animals whose remains are found in the White river formation,
and for the knowledge of whose character we are indebted to the labors
of Profs. Cope, Marsh and others, are the following: A small horse hav-
ing three toes on each foot; the Oreodon, which is sometimes described as
the animal combining the characteristics of the deer, hog and sheep, not
exceeding the last in size. There were also found traces of hyena-like
animals; those resembling the hyrax or cony and some species of edent-
ates; then the Titanotherium or as some of its forms have been called, the
Brontotherium, which resembles the tapir in general habit and structure,
although its size approaches the hippopotamus; also species of rhinoceros
and forms nearly identical with the oppossum. With these are also
found rodents and a few Jermur-like animals.
SAND DIRES.
At various points in the Bad Lands the White river marls and clays
are traversed with thin dikes of sand. They may be seen keeping one
direction for many rods and dividing hard and soft beds alike from the
top of the highest pinnacle to the bottom of the lowest ravine. One of
the best illustrations of this phenomenon was found in the highest point
of the Great Wall, just north of Sage Creek Pass, near the west side of
township 1, south range 16 east. Here were two dikes crossing one an-
other at a small angle running nearly east and west. Across them were
two others nearly north and south. These seems to be examples of sand-
stone dikes, such as are described by Prof. Robert Hay in the proceed-
ings of the Geological Society of America, for 1891, p. 50, as occurring
in northwestern Nebraska, near Chadron. On the Great Wall these
dikes were from 6 to 8 inches in width. The structure consist of thin
lamina on the outer portion of the dike, running parallel with its sides.
About the middle half was of columnar structure, divided by joints running
perpendicular to the walls of the dike. The lamina in the outer portion
were frequently fluted vertically and showed other signs of upward mo-
tion of the mass. Nothing was found forbidding the theory of Prof. Hay
who suggests that they are formed by earthquakes which produced fis-
sures reaching down into the underlying water-bearing stratum. It
seems not improbable that these fissures may have extended through the
Tertiary and upper Cretaceous beds to the Dakota.
These dikes were evidently formed soon after the deposition of the
White River Beds, perhaps at the time of certain eruptions of igneous
rocks in the Black Hills. Similar dikes less prominently developed were
noticed not far from Black, in south Ziebach county, on White river.
GEOI, OGY OF SOUTH DAKOTA. 107
ABSIENCE OF ALKALI.
The white color of the beds and of the water found in portions of the
Bad Lands readily suggest to a traveller who has been acquainted with
alkali basins elsewhere, that the Bad Tands abound in soluble minerals
usually known as alkali.' Such, however, seems not to be the case. In
the Tertiary formation the white appearance of the formation is due to
the color of the clay, and the water, although white and milky, often re-
sembling-curd in consistency, has no alkaline taste and seems to be mostly
a mixture of very fine clay with rain water. Indeed, the presence of
soluble salts would doubtless assist in the floculation and precipitation of
the clays. The water in the Bad Lands receives its clays immediately
after the falling from the clouds; and water will stand for weeks without
its settling. In fact, as the water evaporates, the mixture increases in
tenacity until it becomes thoroughly dried. In the spring of the year
the clay is so thoroughly saturated with water and softened that roads
are entirely impassible, Even later in the season the subsoil may be soft
and yielding, while the surface is dry and hard. Serious accidents have
sometimes occurred from animals and travellers falling into these treach-
erous pitfalls,
THE ORIGIN OF THE WIIITE RIVER BEDS.
All students of this formation agree that it is mainly a Lacustrine for-
mation. As we have sketched the geological history of the region pre-
ceding the Tertiary, it will be remembered that the sea had retired from
the region at the end of the Fox Hills Epoch; that the Laramie formation
was of fresh water origin, either of local lake, or delta deposits of streams.
During the Eocene, large areas west west of the Rocky mountains were
occupied by great fresh water lakes and marshes. Toward the end of the
Eocene the mountain region rose and this water seems to have shifted,
partly to the east and partly to the west, forming in eastern Nevada and
northern California a great lake; and a still larger one over the region of
the great plains from Kansas northward, perhaps beyond the Canadian
line. This lake has been named, by Prof. King, “Sioux Lake.” The par-
tial elevation of the Rocky mountains quickened the action of the streams
and extensive areas covered with mud flats of dry Cretaceous seas con-
tributed their masses of, mud and sand to the building up of the White
river formation. The picturesque representation of this in the Bad Lands
is but a skeleton of its original mass. At first the formation doubtless
extended over the valley of the Cheyenne river, and the abundant erosion
produced by that river has since carried away scores of square miles of
the full thickness of these beds. The portion under consideration was to-
ward the northern side of the lake, which has its greatest depth in west-
108 * GEOI, OGY OF SOUTH IDAKOTA.
ern Nebraska and Wyoming. We may picture to ourselves the shores of
this lake as surrounded with mud flats, for the accumulation of material
doubtless went on rapidly. This is indicated by the general absence of
vegetable remains and of fresh water shells. That vegetation was abun-
dant on higher areas further back seems certain, from the abundance of
vertebrate life which was sustained in the neighborhood. We have al-
ready referred to the possible explanation of the wholesale destruction of
various animals and their preservation in the strata of this formation. It
seems not impossible that storms may have swept the region as at the
present time, although the climate was doubtless much warmer. These
storms would have had a tendency to drive the hordes of roaming ani-
mals over the region, often into the lake. Besides, many of them would
be attracted to it both for drinking and cooling themselves. We find few
traces of water animals, the turtle being almost the only kind. It is not
unlikely that the water of the lake was very muddy, and this may have
been unfavorable to the water breathing animals. Some of the beds of
sand and grit, which have a local development, may possibly mark the
course of the streams flowing from the Black Hills into the lake, and ex-
tending their deposits as the shores became more restricted by the depo-
sition of sediments.
TIHE CIIARACTER OF THIE I, OTP FOREC BET)S.
These are not so prominently developed in South Dakota as in northern
Nebraska in the basin of the Loup Fork. In general this formation in-
cludes the upper Tertiary beds, such as are described collectively as
“Bed F.” in Hayden's section. The present surface is made up of sand-
hills alternating with areas of clay or loam. The sand presents the usual
appearance of dunes. The division between this and the White river for-
mation is not clearly marked. The bed of conglomerate mentioned by
Hayden in his “Bed E.” may be considered as the most convenient hori-
zon for distinction. This appears conspicuously on top of certain buttes
of the Bad Lands; and while it has not been the privilege of the writer
to visit some of the buttes between the Hills and the Missouri river, it
seems from reports to be the same which is conspicuous in Grindstone
Butte and in other prominent buttes in that region west of the Missouri.
Dr. Hayden refers to the Bijou Hills as containing beds of the Loup
Fork formation. We have not been able to obtain his section of these
hills and therefore are not sure of its interpretation. The Bijou Hills are
capped by a formation of greenish and grayish conglomerate, 15 to 20
feet in thickness. This conglomerate is of very irregular structure, show-
ing frequent traces of oblique lamination, contains pebbles of considerable
size and calcareous concretions. Perhaps the most conspicuous feature
-º-
GEOLOGY OF SOUTH DAKOTA. 109
in it is the solidification of some of its layers into translucent, fine grained
quartzite of a greenish tinge. This rock is characteristic and is found
also upon Medicine Butte, near Medicine creek in Presho county, also
capping a number of buttes south of White river, west of the Bijou Hills.
It seems also to form the base of the table land extending south and west
from the Missouri in Gregory county. It seems not impossible that this
quartzite conglomerate may be an extension of the conglomerate capping
the buttes in the Bad Lands between the White river and Cheyenne.
\
FOSSILS IN THE LOUI? FORIK.
f
The vertebrate remains of this formation present very different charac-
ters from the White river. The Brontotherium, Oreodons and Coneys
have passed away and instead we have animals more closely resembling
those still in existence, in many cases belonging to the same genera. In
this formation we have the remains of Mastodons, Mammoths, Camels,
Lions, and of horses equal in size and similar in form to those of the
present.
THIE ORIGIN OF TIII. LOUIP FORIK.
It is universally recognized as a fresh water formation, deposited largely,
if not entirely in a great lake similar to that forming the White river for-
mation and probably a continuation of it. From a movement of the earth's
crust it was shifted more to the east and south so that it extended no
farther north than the White river but much farther south into central
Texas. King named this lake, “Lake Cheyenne.” The elevation of the
Rocky Mountains had so continued that the streams from the west into
the lake was much quickened and hence brought more sandy material,
or we may suppose the erosion had so far removed the softer Cretaceous
beds that it began to extensively carry away the edges of the Dakota
sandstone. At any rate coarser material abounded and sand flats took the
place largely of mud ſlats. These under the action of the winds were
shifted iuto sand ridges and dunes, which probably easily developed
themselves over the dried portions of the former lake bed. The plains
gradually increased in area from the foot of the mountains eastward and
became the home of the herds which in kind resembled those of Africa or
southern Asia of the present time.
THE EXTENT OF TER TIAR, Y BET)S,
We have indicated upon the map in a general way the extent of the
White River and Loup Fork formations without attempting to distinguish
them by a difference in color. In brief, the Tertiary occupies the whole
valley of the White river to the divides between it and the Cheyenne
and Bad river; also the country south of the Nebraska line. The
J
f
110 GEOLOGY OF SOUTH DAKOTA.
margins of this area have been much cut away by the prominent streams
leaving numerous detached outliers which usually are considerably ele-
vated above the surrounding country. Patches of these are found ex-
tending 30 miles west of the Cheyenne between Rapid creek and French
creek. So also north of Bad river the Tertiary extends around the head
waters and doubtless had numerous points between the tributaries on the
north side of that stream. Near the Missouri river the Tertiary beds are
known to occur in the Bijou Hills and in similar hills continuing the range
west of the Missouri; also in Medicine Butte. The Tertiary quartzite
has also been observed a few miles west of Choteau creek on the 43d
parallel, and probably forms the core of the high range of hills between
Lake Andes and the Missouri, The same strata are known to occur just
south of our State a few miles west of Niobrara, and less than 10 miles
southwest of Yankton. In the Wessington Hills a bed of sandstone re-
sembling that in the Bijou Hills is found, about 100 feet below the sum-
mit, near Wessington Springs. Beds have been found in the Ree Hills
which have furnished numerous species of fresh water fishes, which have
been described by Prof. Cope. These may belong to later epoch of the
Tertiary than the White river, but it seems not improbable that the same
formation occurs in Medicine Knoll, near Blunt. Various conspicuous
buttes west of the Missouri to the north and east of the continuous Ter-
tiary beds doubtless contain the same formation and have been so rep-
presented upon the map. i
THE PLIOCENE FORMATION.
More careful study may possibly prove the absence of this age in our
State, but some small areas have been marked upon the map provisionally
to call attention to certain beds of clay and sand that underlie the glacial
drifts in the vicinity of the Big Sioux River. After the Loup Fork Epoch
there seems to have been a change in the drainage of the region or at
least a time of much erosion in the northern part of the area previously
occupied by Lake Cheyenne. In the valleys of the streams we should ex-
pect to find river, or possibly a lacustrine, deposits lower down and of
more recent origin than the well marked beds of the Miocene. It will
be rememberd that Dr. Haydén applied the term Pliocene to the Loup
Fork beds but more recently it has been applied to the formation over-
lying or filling the depressions of the Loup, Fork formation. In western
Nebraska and Kansas such have been called Equus Beds because of the
frequent occurrence of teeth and bones of horses.
Along the valley of the Big Sioux, outside of the outer Moraine,
where the ice of the Glacial Epoch seems not to have been so energetic
in its action, beds of clay and sand are found which are clearly preglacial
GEOLOGY OF SOUTH DAKOTA. ' 111
*
and yet more recent than the surrounding Cretaceous beds. From their
stratigraphic and topographic position they are thought to be contempo-
raneous origin with similar clays and sand in southwestern Iowa, from
which a Megalonyx claw and teeth of horses have been obtained.
Three or four miles northwest of Sioux City, near the railroad crossing
of the Big Sioux, beds of fine sand, overlaid with gray and yellowish
clays with very few pebbles, and these apparently not of northern origin,
are found overlying the Cretaceous beds at a height of 150 to 175 feet
above the river. Beds of Loess lie above them. All these beds of sand
resemble others similarly situated 40 to 50 miles west in northern Neb-
raska. In the sand, bones of mammals have occasionally been found
but as yet have not been fully studied. Mr. H. F. Bain of the Iowa Ge-
ological Survey informs me, that some teeth obtained from these beds
have been pronounced Equus major by Prof. Cope, who therefore con-
siders them Pleistocene.
It seems not improbable that a small area of the same formation may
exist underneath the Loess north of Richland in Union county. A hypo-
thetical Pliocene area has been marked upon the map. Ascending the
Big Sioux river beds of clay have been reported on the Iowa side near
Hawarden, which have been referred by the Iowa Geological Survey to
the Fort Pierre Epoch of the Cretaceous and this may be their real age.
North of Eden, on the Dakota side is an abrupt bluff where an exposure
of gray clay is found 50 to 60 feet above the stream, and above it under
the drift is a bed of sand 5 to 6 feet in thickness. The clay may be of
the Pierre formation; the sand of the lower portion of the glacial drift,
but it possibly corresponds to the sand beds before mentioned near Sioux
City. About a mile west of Fairview, opposite the sharp bend in the
Big Sioux, is an abrupt bluff showing an exposure facing the stream,
The following is the section taken at this point:
SECTION NEAR FAIRVIEW–
8. Slope covered with bouldery clay ------------ 50 to 100 feet
7, Drab, pebbleless clay ---------------------- 14 feet
6. Unexposed ------------------------------- 4 feet
5. Drab clay, thinly laminated, without fossils and
without pebbles --------------------------- 17 feet
4. Fine, gray sand, horizontally stratified, about---12 to 15 feet
3. Slope------------------------------------ 40 feet
2. Dark lead-colored or blackish clay, with broken
bits of shells------------------------------ 5 feet
1. Shale, with large calceaeous concretions: The !
&= -- sº *ssºn ºn tº * * * * * * * * * *-s ºm sº me assº as “as ºs sº 2 feet
level of the stream
112 GEOLOGY OF SOUTH DAKOTA.
On the Iowa side of the Big Sioux, east of Canton, there are beds of
lead-colored clay and sand exposed in the lower railroad cuts. On the
slopes of the hills upon that side south of the railroad, and also in the
steep bluffs northeast of Fairview. S. D., a change in slope, attended with
springs seems to mark a continuation of these beds at nearly equal height
above the stream. The age of this pebbleless clay, as before suggested,
may be of the Fort Pierre Epoch, but nothing requires that explanation.
and against it there is the serious difficulty, that in some places there is a
layer of sand, unconsolidated, between it and the clays, which are clearly
of Cretaceous age. The presence of this sand would strongly lead us to
the concluson that the clay, as well as the sand, is of post-Cretacious or-
igin, while the occasional occurrence of northern pebbles in the overlying
clay, makes the conclusion more reasonable that both are either Pliocene
or the very earliest portion of the Pleistocene.
THE QUATERN ARY OR PLEISTOCENE FORMATIONS.
The Quaternary Age, or as it is sometimes called, the Post-Tertiary
or Pleistocene (more recently), is the shortest of the geological ages, and,
perhaps, should not be ranked as a separate age. Many of the forms of
vertebrate life now living began with this age, while certain larger mam-
mals, like the mammoth and mastodon, have long since become extinct.
The most characteristic feature of the age seems to have been the in-
clement weather, and the consequent extension of a great ice sheet over
the northeastern portion of North America; hence, it is often called the
Ice Age, or Glacial Period. South Dakota illustrates well the different
kinds of work done by nature's forces at that time. The eastern half of
the State was covered with the ice sheet, while the western half was sub-
ject to unusual floods of water, which flowed in great volume down the
valleys of all the principal streams.
It is difficult to classify the deposits of this age according to the chron-
ological order of their formation. It seems rash to attempt it, except in a
general way. The characters of the different deposits, however, are quite
distinctly marked and are generally easily recognized. We may classify
them as (1) Glacial Formations or Drift; (2) Fluvial Formations includ-
ing Lacustrine, and (3) Eolian and Residual Formations.
GLACIAL FORMATIONS OR DIRIFT.
One of the most clearly defined formations of the Quaternary is the
Glacial Drift, which is usually easily recognized by its containing boul-
ders or pebbles of foreign origin, that is, unlike rocks found in ledges in
the region over which they lie. These boulders, moreover, often show
traces of grinding and scratching, in such a manner as is rarely, if ever,
GEOLOGY OF SOUTH DAKOTA. 113
produced by other natural agents than ice; either in the form of glaciers, or
in the form of floating ice, such as icebergs and river ice. The drift may be
conveniently divided into: First, Drift Sheets, where the formation is of
broad extent and comparatively uniform thickness and even surface; and
second, Drift Hills, where the drift formation is associated with more or
less abrupt elevation, such as ridges, knobs, etc. The sheet form of drift
may be divided into Till or Boulder Clay, which is unstratified, and
Stratified Drift. The drift hills may be divided into Moraines, Osars and
Butte Ridges.
TILL-This formation is unique in that it presents often times great thick-
ness without lamination or stratification. It consists of a mixture of sand and
clay with more or less of boulders and pebbles variously scattered through-
out the mass. Its color is usually a rusty yellow above in portions that
have been permeated by surface waters; while the lower portion and the
more compact are usually of a dark drab or blue. The clay is usually
very hard and compact, requiring a pick to dig it. This is particularly
true of the lower portions. Sometimes it contains much calcareous mat-
ter and has been more or less consolidated. It is usually traversed with
joints and cracks running in all directions, and hence the name “joint
clay,” which it is often called. It covers more or less completely all por-
tions of the State east of the Missouri river. Its thickness varies from a
few feet to perhaps 200 feet, averaging 50 to 60 feet. It becomes less
continuous, and broken into patches, as it approaches that stream, and
more particularly the line drawn upon the map as marking the western
border of the drift. The Till is generally believed to have been formed
underneath an ice sheet, resembling the great glacier which now covers
Greenland. Some portions, however, may uktimately be shown to have
been the work of floating ice in connection with lakes or flooded rivers.
TILE STRATIFIED DRIFT.-This is found locally, particularly in val-
leys and near streams, and usually overlies the Till. It is found prom-
inent along certain ancient water courses and near the present streams.
It consists of beds of pebbly clay sometimes interstratified with sand.
The pebbles and boulders in it are usually water-worn, although they
sometimes show traces of striation, indicating their former subglacial con-
dition. This formation is attributed to the action of waters flooding the
valleys during the occupation of the country by the land ice, and especially
the passage of waters resulting from its rapid melting at the time of its
disappearance. |
MoRAINEs.
These may be defined as elongated ridges, or systems of
ridges and knobs, which run continuously. in long winding lines across
the surface of the country. They seem to be confined to no particular
elevation, but vary very much in their height, width and abruptness.
8
114 GEOI, OGY OF SOUTH DAKOTA.
{ *.
They are believed to mark the position of the edge of the ice sheet at the
time when it remained stationary for some time.
In other words, when the ice sheet had a slow motion from the center
toward the circumference, particularly toward the south, it was rapidly
melted away by the sun and the warm winds. Sometimes the motion of
the ice exceeded the rate of melting; in such a case the ice would ad-
vance. At other times the melting would go on more rapidly than the
ice was supplied from its source; in such a case the ice sheet would with-
draw. The moraines were formed when these forces were nearly in equi-
librium. The moraines are sometimes in form of low ridges with gently
sloping sides, especially toward the north. At other times the material
carried by the ice, which would otherwise have been accumulated, seems
to have been carried away by the streams issuing from the ice, or carried
away by bergs floating away from the ice sheet. In other cases the sur-
face of the moraine was roughened with knobs, sometimes rising to the
height of 40 or 50 feet above the surrounding country, and among the
knobs are often pond-holes and lake-basins of all sizes and shapes. These
were formed in some unknown way during the process of the building of
the moraines. As follows from this explanation, there are several mo-
raines marking different stationary stages of the ice during the time of
the withdrawal from the country.
The general position of the moraines may be more clearly understood
if we say that it seems clear that previous to the occupation of the region
by the ice sheet, the Missouri river probably left its present course near
Fort Stevenson, and passed eastward into the present James River Valley,
which it followed southward, and that the various tributaries from the
west flowed east to that valley. The Grand and Moreau rivers probably
passed to the vicinity of Aberdeen; the Cheyenne and Bad rivers, to the
vicinity of Huron, and the White river, by Red and White Lakes, to
Mitchell.
We may suppose that the ice came into our State from the Red River
valley and overflowed the divide between it and the ancient Missouri and
cut down its narrow portion north of the Head of the Coteau in Marshall
county; filled the present James River valley, (then belonging to the Mis-
souri) nearly to the southern boundary of our State; also extending up the
valleys of the western tributaries, before mentioned, west nearly to the pres-
ent course of the Missouri river. The ice at that time covered nearly the
whole surface of our State east of the Missouri. Probably a portion of
the east Coteau, the highest position of the Wessington Hills and Ree
Hills, and the highland northwest of Leola and about Bowdle and south-
ward to Gettysburg were uncovered. This probably marked nearly the
maximum extent of the ice and as it retreated it would naturally form
successive moraines approximately parallel with each other.
} f
GEOLOGY OF SQUTH DAKOTA. 115
The First, or Outer Moraine, which is also the highest, enters the State
over a small area northwest of Leola, in McPherson county, thence it
passed beyond our borders northwest and westward entering again east
of LaGrace in Campbell county. It continues southward through the
west townships of that county to the vicinity of Walworth; thence south-
east, being for a distance feebly developed, to Swan Lake creek, south of
Bangor, where it turns eastward snd northeastward, becoming a conspicu-
ous ridge crossed by several old drainage gaps, one being about 7 miles
east of Bangor, another 2 or 3 miles north of that place. Then it turns
abruptly eastward and then southward, passing east of Bowdle; then
southeast of Hoven and Lebanon to a high point east of Gettysburg.
There it turns abruptly westward and seems to have been quite feebly
developed, being marked only with detached ridges which may be traced
north of Gettysburg, east of Forest City, including the Artichoke Buttes,
Sully Buttes and Snake Butte, north of Pierre, where it turns rather
abruptly eastward and north to Medicine Knoll, near Blunt, which is the
head of a re-entrant angle of the moraine. Then it turns south and seems
to have been carried away between Medicine creek and Chapelle creek either
by the escaping waters, or by a tongue of ice extending to the Missouri river. .
It appears prominent again north of Chapelle creek near the east side of
Hughes county, and extends in an easterly direction to the Ree Hills,
where it agains turns sharply southward and is found developed along
the east bank of Box Elder creek to the vicinity of Gann Valley, in Buf-
falo county; thence by a very complex systems of loops to the highest
point of the Wessington Hills about 3 miles north of Wessington Springs,
where it is magnificently developed, rising about 500 feet above the val-
ley east. It may then be traced southwest, passing south of Crow Lake,
west of White Lake to Kimball, and from there southwest forming a
bend toward Red Lake. Then, feebly developed, it runs southward past
the east end of the Bijou Hills and west of Castalia to a cluster of hills
about 6 miles north of Wheeler. It then becomes more conspicuous and
is easily traced as a high ridge lying east of the Missouri, passing south
of Lake Andes, nearly to the junction of the two branches of Choteau
creek. Another re-entrant fold or ridge constitutes the Choteau Creek
hills. Continuation of the moraine includes a cluster of bouldery hills
north of Niobrara; then comes a wide gap between that point and the
highlands east of Bon Homme. We find it developing another double
fold or re-entrant east of Lesterville, and another east of Clay creek which
constitutes Turkey ridge. The southern point of the latter fold extends
down to and includes, Spirit Mound about 7 miles north of Vermillion.
Then comes a gap between Vermillion river and Brule creek, prob-
ably caused by a narrow ice lobe. The moraine extends along
116 GEOLOGY OF SOUTH DAKOTA.
Brule creek northward to Beresford and on to a high point south
of Canton. It is then feebly developed, or entirely absent, from
that point to the west side of the Big Sioux opposite the northwest
corner of Iowa. There it forms a ridge running west, south of the great
bend of the Big Sioux near Sioux Falls and westward to the East Ver-
million river. It is developed as a high ridge east of that stream north-
ward to the north line of Lake county where it turns abruptly eastward
and forms a sweep in the northern part of that county, leaving it near its
northeast corner. It passes west of Volga and west of Watertown, east
of Waubay and north to a point about 18 miles west of Brown's Valley,
thence it turns sharply southward passing along the east crest of the
Coteau des Prairies passing Summit station on the “Milwaukee,” and
Altamont on the Chicago and Northwestern, in Duel county, and leaves
the State in the southwestern corner of that county. Prof. Chamberlain
calls it the Altamont Moraine from the station last mentioned.
The Second Moraine:-This lies closely in contact with the first, near
the prominent re-entrant angles of that moraine. It nearly coincides with
it northwest of Leola, where it enters the State, turns southward into the
second tier of townships in McPherson county, runs westward north of
Eureka, then into Campbell county, where it turns abruptly southward
and is very much scattered over the surface of the country; then it turns
southeast to the hills north of Bowdle, where it joins the first moraine
again. It lies as a lower range of hills parallel with that moraine, till it
reaches the line of the Chicago and Northwestern, west of Seneca. There
it turns eastward and forms a sharp ridge, pointing northeastward. From
that point it makes a curve to the south, southeast and east, till it rises in
conspicuous hills again, about two miles south of Faulkton. After this
prominent development it becomes less conspicuous and returns along the
north branch of Medicine Creek to the northwest corner of Hyde county,
where it turns southward and forms a rude curve around to the vicinity
of Highmore, where it crosses the railroad, and skirts the Ree Hills to
their eastern end, southwest of Miller. From this point, owing to the ir-
regular form of the first moraine, it has not been satisfactorily traced,
until it again appears in the form of prominent knobs, south of Wessing-
ton station, and at other points along Sand Hill creek to the north line
of Jerauld county, where it is represented by scattered hills lying east
of the north branch of Fire Steel creek. It includes the prominent line
of knolls west and south of Woonsocket. Then it sinks into the level
plains surrounding, a few miles further south, and we see no more of it
until south of Fire Steel Creek, west of Mitchell. One of the most con-
spicuous portions of this moraine is known as the Enemy Creek Hills,
south of Mitchell. Here it is running nearly east, curving toward a
GEOLOGY OF SOUTH DAKOTA. 117
prominent knob east of the James river, east of Mitchell. From that
point the moraine follows down the east side of the James river to the *
vicinity of Menno. There it turns abruptly northeast, passing around
the north end of Turkey Ridge, and leaving it south of Marion Junction.
It passes west of Parker and constitutes the divide between the East and
West Vermillions, passing a few miles west of Montrose, between Win-
fred and Howard, west of De Smet, along the west slope of the Coteau,
west of Clark, Bristol and Fort Sisseton, to a prominent knob, know as
“Head of the Coteau,” located where the west line of the old Sisseton
Indian Reservation crosses the north line of the State. From there the
moraine lies on the slope of the east Coteau, passes the “Milwaukee’”
railroad in the vicinity of Marvin, to the “Northwestern" railroad at
Gary, on the east line of the State. Prof. Chamberlin calls it the Gary
Moraine.
The Third Moraine:–This moraine was formed apparently by the re-
mains of the ice sheet after it had been restricted to the level land of the
James River valley. It is, in general, feebly developed and the hills are
less continuous than those of the Second Moraine. It frequently shows
small semi-circular loops. It enters the State west of Maple river in
in northwestern Brown county and runs southwest, east of Leola to Ips-
wich, then south quite directly between the branches of Snake Creek,
about 10 miles east of Falkton, to 8 or 10 miles northeast of Miller where
it turns eastward and then northeast on the east side of Turtle Creek to
the vicinity of Redfield where it is conspicuously developed, and thence
eastward south of the peculiar bend on the James River. It does not
cross that stream but turns again suddenly west of south, past Crandon,
and west of Hitchcock, to the vicinity of Wolsey. Then it forms a semi-
circular loop towards the south, crossing the “Northwestern” railroad again
east of Cavour. It then turns north and lies approximately parallel with the
second moraine approaching it gradually toward the north. It may be
traced in a low system of foot hills around the foot of the East Coteau,
passing for a short distance out of the State. It lies south of Skunk Lake
and from there forms a curve toward the northeast where it forms a con-
spicuous cluster of hills known as “Lightning's Nest;” then it turns ab-
ruptly south along the 97th meridian to the Minnesota river, which it fol-
lows for a distance and keeps the southeast direction past Wilmot and
east of Milbank to a knob on the Yellow Banks known as Mount Tom.
In the Minnesota Valley it is known as the Antelope Hills.
The Fourth Moraine;—This is a small loop formed by the last trace of
the ice sheet entering the State, in the northwest corner of Brown county
it describes a rude semi-circle passing Amherst, and south of Britton, and
leaving the State at the foot of the Head of the Coteau, with the third
moraine.
;
118 GEOLOGY OF SOUTH DAKOTA.
This moraine, though, so short, is interesting as being the main barrier
which prevents the waters on the upper James river flowing eastward into
the Red River of the North. The moraine near Heckla consists largely
of sand and the region east of the moraine is lower than the water in the
James, on the west side of the Loup near that stream, so that there seems
to be sometimes a seepage of water through the moraine eastward. This
was observed at a point little north of our boundary, when the James
was very high.
OSARS.
These are peculiar bouldery ridges which consist largely of stratified
material, but of more regular order than the moraines. They may some-
times be traced for miles in nearly continuous lines. They are largely in
the bottom of valleys or old water courses. They frequently branch like
a stream. They are usually much more bouldery than the surrounding
country. We have only a few in our State, but they are of a very inter-
esting character. Several of them may be found north and east of Bowdle
crossing and lying on the outer slope of the first moraine. A very inter-
esting example, about two miles in length, was found southeast of Copp
in the northwest corner of Hyde county. It lies in the bottom of an old
drainage channel crossing the second moraine toward the northwest.
Some imperfect examples of this formation may be found north of Water-
bury in western Jerauld county. A very regular one, but not promi-
nently developed, is found south and southeast of Crow Lake in Jerauld
county crossing the first moraine toward the northwest.
Another, quite conspicuous in structure is found northeast of Montrose
leading along the north side of a lake in an old drainage channel of the
first moraine leading to Skunk Creek. Otherinteresting examples were found
west of Sioux Falls near Wall Lake. Less perfect examples are found
in many other drainage channels, as for example the channel south of
Lake Andes and the one at Pratt Creek.
These Osars are of problematic origin. It is not unlikely that different
forms closely resembling one another are due to quite different conditions.
Some within the moraine have been quite clearly shown to be the
work of streams flowing upon or underneath the ice sheet. Those on the
outer slope of the principal moraine may have been formed like the bould-
ery ridges described by Lyell as occurring in the lower St. Lawrence,
which he ascribes to the work of floating ice and to ground ice.
Bl]TTE RIDGES.
These, perhaps, should not be grouped with the drift deposits, for they
are supposed to be in part of lacustrine origin. But, since they are
prominently strewn with glacial drift, it seems fitting to mention them in
GEOLOGY OF SOUTH DAKOTA. 119
this connection. Besides, we may consider their origin not certainly de-
termined. The most conspicuous examples of this formation are found 2
west of the Missouri river on the north slope of the Fox Hills. They
are observed about 7 miles south of the Moreau and 15 or 20 miles west
of the Missouri, in the vicinity of Virgin Buttes. They may be described
as a series of flat-topped ridges 10 to 50 feet in height above the sur-
rounding country, having a breadth of from 2 to 6 rods. These ridges
lie in a nearly continuous line, their summits are flat and thickly strewn
with granite and limestone boulders. The top of the whole series lies on
almost exactly the same level. A series was traced from 10 to 15 miles
running in an east, and west direction. According to reports, a ridge
resembling these crosses the Moreau river about 20 miles from its mouth
and turns northward, running approximately parallel with the Missouri
river. The ridges mark the limit of the Glacial Drift, and therefore cor-
respond to the line on the map indicating the limit of that deposit. The
explanation which seems most satisfactory is that these boulders were
dropped by the floating ice upon the shore of a temporary lake occupy-
ing the region outside of the first moraine north of the Fox Hills. This
lake was probably formed by the Ice Sheet damming the Missouri river
and its western tributaries by entering their ancient valleys on the east.
The water would rise until it overflowed the low places in the divide,
which, previous to the Ice Age, separated the Moreau and the Cheyenne
rivers. This ancient and bouldery beach has become a line of ridges by
the rapid erosion of the Cretaceous on either side.
FLUVIATILE FORMATIONS.
We have already referred to the strong contrasts in topography of our
State. It therefore follows that the action of streams has been unusually
marked. The Missouri and Cheyenne with their tributaries have been
particularly active in the recent work of erosion, while some of the
streams in the eastern part of the State have during and since the glacial
epoch, deposited much material. There are many examples, especially
about the Black Hills, of the effect of Ferrell’s law, which is a result of
the earth's rotation, upon the erosion of streams and consequently upon
the resulting topography. The streams have quite persistently shifted
to the right, and as a result the streams lie nearer their right hand divide,
and on that side the terraces are less frequent and the slope generally
much more abrupt. This is beautifully illustrated in the streams radiat-
ing from the Black Hills as also in the Cheyenne which receives them.
We would include under this head all deposits or formations produced
by flowing waters; and even those of lakes which are commonly expan-
sions of streams. We except of course those directly influenced by landice.
120 GEO LOGY OF SOUTH DAKOTA.
Here we should place, (1) sheet-like accumulations of streams on a
plain to which we may apply the term Aqueous Drift, including delta and
“alluvial fan” deposits; (2) Loess; (3) River Terraces and (4) Fluvio-
Lacustrine deposits.
AQUEOUS DRIFT.
Under this head we would include an extensive deposit of boulders and
gravel overspreading quite generally the country around the Black Hills
for a distance of from 100 to 150 miles. It seems to have been nearly
continuous at first over the whole country. It is found usually capping
the high pinnacles of the Bad Lands between the Cheyenne and White
rivers. It is found far north to the Head waters of the Moreau river.
That the material has been derived from the Black Hills seems evident
not only from the nature of the rocks, but by the gradual diminution in
size of the pebbles and in thickness of the deposit according to distances
from the Hills. Favorable opportunities for examining the internal struc-
ture have not been found; but it seems clear that the boulders and peb-
bles are mixed with finer material in a very indiscriminate way rarely
showing distinct stratification. This may be partly due to the changes
that have since been wrought in it by action of frost, by washing on in-
clined surfaces and the work of burrowing animals. In the bottom of
watercourses in the Bad Lands limited deposits of apparently unstratified
pebbly clay were observed. These seem to be clearly the work of streams.
In like manner it seems probable that the Aqueous Drift upon the up-
lands may have been formed and been partly unstratified in many places.
The thickness of the deposit has not been determined at many points.
On some buttes in the Bad Lands it was found 3 to 4 feet in thickness.
Nearer the Hills it appears much thicker.
There are probably few areas which represent the upper surface of the
original deposit, yet such are believed to occur at points where erosion
has not been active, as for example, on the divides between the streams
flowing from the Hills eastward, as the Elk, Rapid, and French creeks,
and also between the Cheyenne and the Head Waters of Bad and White
rivers. The elevation of these comparatively level surfaces, in localities
named, gently declines away from the Hills. Northeast of Rapid City, ac-
cording to the topographic map of the United States Geological Survey,
the altitude of this plain is about 3,400 feet; east of the Cheyenne river,
in its northerly course, it is estimated to be about 3,000. The superficial
appearance of the drift as it lies upon the upland frequently reminds one
of the Glacial Drift, already described; the bowlders, however, are never
striated. This Aqueous Drift has been referred by Prof. Jenney to the
action of ice floating in a fresh water lake around the Hills. Prof. Crosby
GEOLOGY OF SOUTH DAKOTA. 121
concludes that it has been left as a residuum after the removal of the
softer portions of the Tertiary beds, which he conceives at one time cow-
ered the whole region where the drift is found on the upland. So far as
has yet been found there are no traces of glacial action in the Black Hills.
Therefore, the suggestion of Prof. Jenney cannot be accepted. If Prof.
Crosby is right the transmitting power which first distributed them must
have been wave action. When we consider the slope of the surface
which appears to have been covered by the drift, and note that it corre-
sponds with the terrace-like formation inside the outer rim of the Hills, it
seems reasonable to suppose that the general distribution of the drift was
accomplished by the various streams flowing from the Hills over the plain
surrounding, at a time when the slope was slight, the water abundant,
and the deposition of material rapid. This may be referred to a time pre-
ceding the excavation of the present valleys. In other words, this drift
may be considered as a kind of delta deposit formed by streams shifting
to and fro upon a plain of deposition. Such a condition of affairs seems
probable at an earlier time when the ice was occupying the eastern half
of the State.
The Cheyenne river is the main stream draining the Hills, and has, therefore,
formed more numerous and conspicuous terraces. These correspond, at
least some of them, to prominent terraces along the Missouri, which have
already been mentioned.
Distinctions Between the Eastern and Western Drift:—From what has al-
ready been said, one would expect a mingling of the erratics from the
Black Hills with those brought by the ice sheet from the north. Such is
found to be the case, not only in the terraces along the Missouri river,
but even in the outer moraine itself. It is often a perplexing question
when examining the drift to determine whether a specimen has come
from the north or the west. Many, as granite, hornblendic and mica-
schists, and greenstone seem indistinguishable often times, though they
have come from the different sources. The northern drift, however, alone
contains boulders of red quarzite, such as is found at Sioux Falls, and
boulders of the white, fine-grained magnesian limestone, which is Sup-
posed to have been derived from the beds of the upper Silurian or Devo-
nian in the Red River valley of the north. The western drift never con-
tains these. On the other hand, it abounds in flat pieces of chalcedony,
which have come from the veins in the Tertiary beds, and coarse-granite
or feldspar pebbles derived from the granite masses about Harney Peak.
Also pebbles of trachyte and porphyry, which, after once being seen will
be quite easily recognized as distinct from corresponding rocks coming
from the north.
122 GEO LOGY OF SOUTH DAKOTA.
*,
I,OESS,
This term is derived from a German name for a similar deposit found t
on the banks of the Rhine and Danube rivers. It may be described as a
yellowish loam, very homogeneous in structure, showing little or no trace
of stratification, and with a tendency to form joints running verti-
cally. It has been called Bluff Deposits by the geologists of Missouri
because it is so prominently developed along the bluffs of the Missouri
river, in Iowa and Nebraska and northern Missouri. This deposit is
supposed by many to have been formed in lakes or flooded rivers from a fine
mud, which had accumulated in the ice sheet, partly from the dust blown
upon its surface and partly from the grinding of the rocks underneath.
Others suppose that while it derived much material from this source,
it may have received as much, if not more, from the washing of the Ter-
tiary beds on the western plains. It is developed in our State only in a
very narrow region, although it overlies all of eastern Nebraska and
western Iowa. It is most deeply and typically developed in Lincoln
and Union counties between the outer moraine and the Big Sioux river,
where it is found from 50 to 150 feet in thickness. It is also found out-
side the first moraine around Sioux Falls, covering much of Minnehaha
and Moody counties. It gradually thins out toward the north, and Min-
nesota geologists have found in their State adjacent, that it is limited by
a contour line of 1,550 feet above the sea. It forms a most valuable sub-
soil because of its under-drainage in wet seasons and by capillary action
supplying moisture to plants in dry seasons. It was probably formed
either shortly before, or during, the occupation of the first moraine by the
ice sheet.
Though what we have just described is most properly called the Loess,
similar formations are found of much later origin covering the various
terraces of the Missouri and other streams. Along the Missouri particu-
larly, the high terraces, as about Pierre, are occupied sometimes with 30
to 50 feet of the buff-colored loam, indistinguishable from the Loess.
Beyond the limits of our State, as around Sioux City, and more distinctly
further south, there is a high terrace arising about 100 or 150 feet above
the Missouri river, which is mainly composed of Loess-like material. This
has often been confused with the higher Loess, which, we believe, has a
much older origin.
RIVER TERRACES,
Very striking examples of this feature are found along the Missouri
river and the Cheyenne and in less striking degree along White, Grand and
Big Sioux rivers, while some streams scarcely exhibit them at all. We will
not attempt a complete classification or description of these river terraces,
GEOLOGY OF SOUTH DAKOTA. 123
but will briefly mention a few typical cases which we have observed. On
the Missouri, near the mouth of Moreau river the following terraces were
noted: The lower bottom about 10 feet about the river and a higher one
about 30 feet and other terraces at 63, 105, 144, and 210 to 240. At Fort
Bennett the terrace at from 260 to 300 feet, is wide and covered quite thick-
ly with loess-like loam, with a thick deposit of clay and northern boulders
underneath. At Oahe, above Pierre, terraces were noted at heights of
10, 62, 118, 172, and 310 feet above the river. At Pierre a similar num-
ber of terraces is found. Near the mouth of Platte creek, in Charles Mix
county, there is a remarkable development of bouldery terraces, one from
from 300 to 350 feet above the Missouri and another 90 to 120 feet. Be-
Below Wheeler the two higher bouldery terraces, which have been traced
above, seem to come together on the level of the lower and this continues
down the river at altitudes as follows: Yankton Agency, 130 to 240;
Running Water, 200; Yankton, 120 to 145; and Vermillion, 80 to 140,
where it presents features of glaciation instead of being purely a river ter-
race. This terrace probably corresponds with the high terrace south of
Sioux City which is composed mainly of loess and also with the terrace at
Blair in Nebraska of similar composition. Further notes by the writer
on these terraces will be found in Proceedings A. A. A. S., 1888, Vol.
XXXVII., p. 203.
On the Cheyenne river, about 20 miles above its mouth there is found
a very high terrace, composed in its upper portion largely of boulders,
apparently from the Black Hills. This terrace is at an altitude of about
200 feet above the stream. Another one clearly defined lies 370 feet,
while a narrow bouldery ridge, which appears to be a remnant of a ter-
race lies 432 feet above the river. On the Cheyenne near its junction
with Elk creek the following terraces were noted: Upon the west side
one about 27 feet; another, wide and showing on both sides of the river,
cutting across the present bends of the stream, 240 to 245 feet; and
another being a continuation of the highest terrace which is well devel-
oped along Elk creek, 335 feet. Upon the east side of the stream a very
regular devlopement of high terrace was found as follows: 190 to 200;
240, 285, 335; while the summit of the upland further east which showed
frequent lake beds, was 550 feet. This latter surface is believed to be
part of the original plain upon which the “aqueous drift” was deposited.
These terraces are of level surfaces of uniform width and gentle slope.
Further up on the Cheyenne these terraces are less numerous, but two
are quite distinctly traced as far south as the mouth of Fall river. These
two abound in boulders in their upper portions and probably correspond
to those 336 and 240 feet above the stream at the mouth of Elk Creek.
Along Elk and Rapid creeks, and probably all of the streams of the Black
124 GEOLOGY OF SOUTH DAKOTA.
Hills there are two high broadly developed terraces traceable. This ap-
pears not only outside of the foot-hill range but in the Red Valley, at
least this is true of the highest one.
It was observed above Rapid City, and near Beaver creek, inside of
Buffalo Gap, also at Hot Springs. At both these localities the boulders
are very abundant and have been consolidated into a conglomerate by the
action of the calcareous waters of the streams. At this point they lie 40
or 50 feet higher than the present streams. Outside of the gaps the
streams rapidly descend while the terraces continue more nearly upon a
level, hence the terraces which are more than 100 feet above Rapid creek
at Rapid City are more than 200 feet above it at its mouth, while the ter-
race which is but 20 or 30 feet above the stream near the Gap is about
100 feet higher than the stream at its mouth.
TTIE AI,I,UVIAL FORMATIONS.
Under this head we include the broad bottom lands along the Missouri
and other prominent streams. The term is partly applicable to the lower
land or flood plain which lies from 10 to 30 feet above the water. This
has a subsoil of sand or gumbo. The latter having been formed in quiet
water, the former having been deposited by the current as it has shifted
to and fro. Minor terraces may be seen along the banks of the streams;
but they mark temporary floods or local variation of level rather than any
continuous cutting down of the stream. These alluvial deposits rarely
contain coarse material. At a height varying from 10 to 25 or 30 feet
there are frequently second bottoms, as they are called, which have simi-
lar composition to that already described. These are really not of a dif-
ferent class of formations from the higher terraces, but they are composed
of finer material. They usually have very rich soil. In terraces higher
than 100 feet above the present stream the boulders of the glacial drift
generally occur and probably indicate that the ice had not completely
withdrawn from the region at the time of their formation.
I, ACUSTRINE FORMATIONS.
Under this head we have thin deposits locally developed in the various
small basins which abound on the drift, with a few very shallow ones west
of the Missouri beyond the influence of the formation; and the quite ex-
tensive beds which fill the basin of ancient Lake Dakota, in the James
River Valley. A few others less important of the same class.
The former are very numerous, and together constitute an important
part of our area. They are often filled several feet with fine material,
and often contain rich soil, with more moisture than the surrounding coun-
try. On the other hand, in wet seasons they may be flooded. This diffi-
culty, however, may usually be remedied by drainage.
t f
GEOLOGY OF SOUTH DAKOTA. . 1:25
An interesting feature of these lake-beds is the common occurrence of
a heavy deposit of boulders like a tumble-down stone fence, surrounding
much of the margin. This is the work of ice, with fluctuations of water-
level and waves. \.
Lake Dakota was a body of water 5 to 25 miles wide and over 120
miles long, when the Ice Sheet occupied the F ourth Móraine. It is now
represented by the remarkably low level plain stretching from Oakes,
N. D., to Huron. It is now filled to the depth of 25 or 30 feet with a fine
silt, resembling loess. It is throughout about 1,300 feet above the sea.
An earlier stage it extended to Mitchell, but the deposits in that ex-
tension are more stony. Very even and generally level areas, probably
due to still older lakes, occupy extensive portions of Aurora, Hutchison,
Brule and other counties. Some of these grade imperceptibly into true
glacial drift.
EOLIAN OR RESIDUAL LOAM.
Some authors have referred the Loess largely to the transporting power
of the wind, and it seems probable that much of the Loess has been
shaped more or less by the action of winds. We would include, however,
under this head not the Loess or any portion of it, but rather a very shal-
low loamy material lying over the surface of both the glacial drift,
where it perhaps cannot be distinguished from the glacial deposits, and
also over driftless portions of the State. The Cretaceous and Tertiary
clays seem to contain a considerable larger proportion of silicious ma-
terial near the surface in the form of almost impalpable sandgrains than
deeper down. This is more apt to be true of flat areas which have not
been exposed to erosion. These in part may be considered of residuary
origin, the fine sand having been left behind in the erosion of the upper
portion of the clay. But while this subject has not been studied suffi-
ciently to arrive at a definite conclusion, it seems not improbable that
the silicious material near the surface has been mainly derived through
the action of the winds from the sandy areas surrounding.
LIFE IN TIII QUATERNATRY.
Many would, at first thought, not expect much development of life in
the vicinity of the great glaciers of the Ice Age. But recent explorations
of Alaska, (Thirteenth Annual Report United States Geol. Survey) have
revealed dense forests, not only near the glacier, but upon its surface,
over many square miles of its stagnant portions,
The Boulder Clay of our State not infrequently contains fragments of
wood sometimes of considerable size. The Loess, further south, quite
frequently contains many specimens of land snails with a few fresh water
shells, but few, if any, have been observed in the true Loess, in or near
126 . GEOLOGY OF SOUTH DAKOTA.
our borders. The loess-like loam capping the river terraces has been
found to contain many of them in places, as at Pierre.
Much more interesting are the remains of mammoths and mastodons,
which are not very rare outside the First or Outer Moraine. Two large
tusks, teeth and fragments of large bones belonging to a mammoth, Ele-
phas Americanus, have been recently unearthed at Sioux Falls. A fact
significant of their comparative recency, is that they lay in loamy sand
capping a high terrace about 60 feet above the Big Sioux river above the
falls, and only 5 or 6 feet below the original flat surface of the terrace.
The bones were not perceptibly worn nor much scattered. All seems to
indicate that the monster perished on the spot when that was a flood plain
of the Big Sioux, which is believed to have been when the ice sheet oc-
cupied the First Moraine. The tusks were over six inches through at the
base and the portion remaining was over seven feet long and much
curved. Other bones which from reports, appear to have been of a mas-
todon, have also been dug up near Sioux Falls.
Inside the Moraine and therefore more recent, have been found old
muck beds with tamarack logs and fresh water shells in old lake beds.
I examined one twenty feet below the surface north of Grand View,
Douglas county. It was above the Boulder Clay.
CHAPTER VIII.
ERUPTIVE ROCKS.
We have completed in the foregoing chapters our consideration of the
sedimentary rocks. Under the head of eruptive rocks we include all that
have been deposited in their present position, while in a molten or plastic
condition. We have already alluded to the granite in our discussion of
the Archean because its eruptive origin has not been conceded by all.
Eruptive rocks are found in various forms and conditions. They occur
in dikes, sheets, lenticular masses and laccolites, which have been already
defined on page 20. They have also sometimes been forced upward with
sufficient energy to reach the surface and overflow in broad streams, as
in the case of modern volcanoes. As a general rule, molten eruptive
rocks have a finer crystalline surface, according to the rapidity with
which they have cooled. Where they have cooled slowly deep below the
surface they are usually coarse-grained. In large overflow masses there
may be a glassy or slag-like structure near the surface, because of its sud-
den cooling, while below the surface the appearance is more like that of
ordinary stone, the grains being, perhaps, large enough to be easily seen.
The eruptive rocks in our State cannot be classified easily according to
their age, because the time at which they have been intruded or depos-
ited has not been made out with sufficient definiteness. We may, how-
ever, classify them with reference to their composition, and will also give,
as definitely as present knowledge will permit, the probable time of their
outflow. They represent the different kinds, called Diorite, Diabase,
Granite, Rhyolite, Trachyte and Phonolite. •:
DIORITES.
Under this head we include, not only the massive rock which is com-
posed of hornblende and plagioclase or triclinic feldspar, but also hornblen-
dic schists, for more recently the latter have been found to be really some-
times of eruptive origin. The Diorite of the Black Hills seems to have
been strangely overlooked by Newton. Boulders of this rock are found
frequently over the region east of the Hills. He may have considered
them portions of the schist or slate series and therefore of fragmental
128 GEOLOGY OF SOUTH DAKOTA.
origin, but as has been pointed more recently by Prof. Van Hise, from a
microscopic study of them, corroborated by further field study, they are
distinctly eruptive and are probably the oldest eruptive rocks in the Hills.
Prof. Carpenter discovered a dike of diorite, sometimes more than 1,000
feet in width, traversing completely the slates, or eastern series of
Archean rocks. The distribution of these rocks has been briefly treated
by writers upon the subject. They are believed to have but little or no
economic value.
Qº TXIAIBASE,
This is a formation of igneous rocks composed of augite and various
species of feldspar with sometimes other ingredients. Under this head
comes the eruptive, rock already referred to as occurring northeast of
Sioux Falls along the Split Rock. Prof. Hobbs, who has studied it, pro-
nounced it an Olivine Diabase.
The dike of diabase runs in a north and South direction. Where first
observed it was very much weathered. Where it has been covered by
overlying clays it shows the tough compact rock which occurs in the
boulders of the drift. An interesting feature of this dike is the compact
slates which bound it on either side. The country rock is the Sioux
Quartzite.
It may be in place here to mention briefly the recent discovery Of
quartz porphyry not far from our borders. This was found in the bot-
tom of a deep well at Hull, Iowa. From its character it is inferred that
it was formed as an overflow upon the crystalline rocks, probably the
Sioux Quartzite, previous to the deposition of later formations.
G R A NIT.E.
This well defined group, composed of quartz, feldspar, and mica, with
occasional other minerals, has already been treated much at length under
the Archean, and we need not speak further about it.
* RHYolſTE, TRACHYTE, AND PHONOLITE.
These three formations of igneous rock will be conveniently treated to-
gether, both because of their gradation into one another and their proba-
ble eruption at about the same time. They are often called porphyry.
These constitute a very conspicuous feature of the Hills. The most sym-
metrical and picturesque peaks are composed of them. They vary in
coarseness of structure, from a distinct crystalline character with quite
large crystals to formations in which separate grains are scarcely visible.
They all present a particularly homogenous though fine grained mass of
a pale green, pinkish or grayish color, within which are crystals, usually
transparent, which are quartz, or a kind of feldspar, called sanidin.
GEOLOGY OF SOUTH DAKOTA, 129
f
The Rhyolite contains more quartz than feldspar, both in the fine grained
masses and in coarser grains. It usually also has a lighter color and is
harder. - $
Trachyte contains little or no quartz, and the larger grains are almost
entirely sanidin.
The Phonolite is usually finer grained and derives its name from its
fragments ringing like metal. All these rocks break with comparatively
smooth and even joints and separate into angular pieces. The more
prominent peaks formed by these rocks are Custer Peak, Terry Peak,
which is the highest of the kind in the Black Hills, Crow Peak, Black
Butte and Bear Butte. There are also many others of smaller size in the
northern portion of the Hills. Custer Peak is based on the Archean
slates. Terry Peak has Carboniferous and Potsdam strata high up upon
its eastern slope. Crow Peak is thrust up through the purple limestone
of the Red Beds. Bear Butte, outside the outer rim of the Black Hills,
has been thrust up through the Cretaceous rocks. The Dakota Formation
rises in a ring-like ridge nearly surrounding it. The Benton clays lie
nearly horizontal about it. Therefore Prof. Winchell supposed that they
had been deposited since its elevation. There are also outflows near Til-
ford, north of the Elk Creek Canyon. At that point the rock has a fine
grained, light green color, containing crystals of white feldspar. It oc-
curs in dikes and laccolite masses in the Carboniferous limestone.
The contact between the porphyry and the limestone was clearly traced
at one point and exhibited an irregularly arched form. The limestone was
altered for only a few inches from the line of contact. The igneous rock
showed columnar structure for several feet from the exterior, the columns
being at right angles with the surface of contact.
A large number of the peaks of this, lie beyond our borders. One be-
ing the Inyan Kara, and another the very singular tower-like Mato
Tepee, or Devils Tower.
All observers who have studied these peaks agree that no clear traces *
have been found of a volcanic overflow of lava. It is known to be a fact
that all igneous rocks yet found in the Black Hills have no characters
which indicate that they were cooled at the surface. Moreover no clear
case of their overlying a weathered surface has been found. Newton re-
ports one doubtful case which he afterwards concluded was due to intru
sion and not to surface overflow. Newton supposes that the igneous
rocks were deposited in and underneath the Cretaceous strata. Prof. Car-
penter considers that they are all laccolitic formations. The strangely
columnar form of Mato Tepee has been explained by supposing that the
present peak is the cooled core of a volcanic cone; that the lava filled the
chimney or throat of the volcano and cooled while the volcanic tufa and
9
130 GEOLOGY OF SOUTH DAKOTA.
3
and other soft rocks which constituted the cone were surrounding it. This
is indicated by the long vertical columns running perpendicular for 500 or
600 feet, for it is a law of the cooling of the volcanic rocks that the colunms
'formed by the shrinking or the rocks in their cooling run perpendicular to
the exposed or cooling surface. Bear Butte seems to be of some-
what similar form, the igneous rock constituting a core of larger diameter.
From this it may be inferred that volcanic outflows occurred and that
erosion since that time has carried away the surface rocks of igneous
character with the soft clays upon which they lay. A fact which may
slightly corroborate this view is found in the occurrence of pebbles of
pitchstone in the conglomerate in the Loup Fork beds.
THE TIMES OF THE OUTFLOWS.
There were at least three times of eruption of igneous rocks, one
of the Diorites, one of the Granites and one of the Trachytes, Rhyo-
lites and Phonolites. The age of the Diabase very likely may correspond
with that of the Granite or Diorites. From the fact that they occur in a
different portion of the State their relative ages cannot be clearly deter-
mined.
The Diorite outflows necessarily were formed later than than the depo-
sition of the material of the slates in fragmental form. Prof. Van Hise
suggests that the eruption of the Diorites took place contemporaneously
with the formation of the slaty cleavage which is most manifest in the
eastern portion of the Archean area. The irruption of diorite and the
metamorphism of the slates must have taken place at a greater depth be-
low the surface and the pressure attending
rock below is supposed to have generated the slaty cleavage in the sur-
rounding fragmental rocks which took place at the time of their change
to a crystalline state.
The age of the granite we have already discussed. Its occurrence in
lenticular masses, lying approximately parallel with the planes of slaty
cleavage, suggests its occurrence later than the diorite is strongly indi-
cated by the entire absence of granite in the diorite. The eruption of the
granite, according to Prof. Van Hise, probably attended the develop-
ment of the schistose structure which is most perfectly developed in the
vicinity, and in different planes from the slaty.
Prof. Crosby came to the conclusion that the Harney Peak granite is
older than the newer series of schist, which are overlaid by the Potsdam
beds, traversed by large intrusive dikes and sheets of porphyry. These
porphyries contain not only fragments of the schist and slates, but also
occasional fragments of granite which he supposes must have been brought
up from lower down. We fail to see that this proves more than that the
porphyries were erupted later than the Potsdam.
g the movement of the molten .
GEOILOGY OF SOUTH DAKOTA. .# 131
\
f
THE A.G.E OF THE PORPHYIRY ERUPTION.
We here use the term porphyry to include the three varieties, before
spoken of as rhyolite, trachyte and phonolite Newton concludes that
the time of the porphyry outflow was later than the Fort Benton Creta-
taceous and earlier than the Miocene. This he infers from the fact that
the intrusion of the porphry distorted the beds as late as the Fort Ben-
ton, and because Mr. Jenney found in the conglomerate at the base of the
White River formation, not only pebbles of granite and feldspar, but the
pebbles also of trachyte. Prof. Carpenter judges that the eruption took
place at the close of the Cretaceous, from the fact that the Fort Benton
lies undisturbed at the base of the Bear Butte. He reasons that the later
Cretaceous formations overlay it and constituted the surrounding walls
which limited the porphyry core now constituting this peak. He agrees
with Newton in concluding that the eruption must have occurred before
the Miocene, because of the pebbles found in the beds of that formation.
As before stated, Prof. N. H. Winchell inferred from the horizontal position
of the Fort Benton clays at the base of Bear Butte that they were de-
posited subsequent to the upheaval. According to his view, the eruption
probably took place during the Jura Trias. He would attribute the po-
sition of the Dakota at the base of Bear Butte to its deposition on abrupt
slope. He would probably attribute the relative height at which the vol-
canic rock stands above this later formation, to the former existence of
the tufa, which may have removed previous to the Cretaceous. It seems
that Prof. Carpenter's conclusion has this in its favor, that from the
heights of the present peaks above the Benton, as seen in the case of Bear
Butte and Bear Lodge, there must have been several hundred feet of
sedimentary deposits which gave shape to the present porphyritic rocks.
We can scarcely attribute that effect to volcanic tufa which might have
been built upon the Benton or Dakota. For, if such had been the Čase,
we cannot conceive of the entire removal of all such formations from that
region. If, on the contrary, as he supposed, the eruption took place after
the deposition of the Pierre or even the Fox Hills, the removal of these
beds would very naturally carry away the loose volcanic tufa with it, and
so account for the absence of sub-aerial surface of volcanic rocks from the
region. Moreover the tufa and the comparatively impervious character
of the clays may have had something to do with the concentration of the
lava to small circular vents, especially where the outcrop was remote from
the older rocks and therefore the greater of the clays. It will be re-
membered that there is a gap in the deposits about the Hills from the Fox
Hills to the Miocene. This may be accounted for by the upheaval pre-
ceding and attending the volcanic disturbance. While the the accumu-
132 GEOLOGY OF SOUTH DAKOTA.
lation of water subsequently in the great Miocene lakes, surrounding the
area, may perhaps be traced to the subsequent subsidence resulting from
the escape of molten rocks from below and the secular cooling of the
region.
Rhyolite and trachyte sometimes form vicid lavas, which are capable of
rising and standing in dome-like masses without walls to limit them.
Examples of these are found in the Isle of Bourbon, where they are
known as “mamelons.” If the prominent peaks already described were
of this nature, it is unnecessary to assume that crataceous formations
formerly existed around them. The eruptions may, therefore, have taken
place at an earlier stage. Were this the case, however, we see no escape
from the reason why there should not be evidence of the occurrence of
fragments of volcanic rocks scattered in the Cretaceous formations in that
vicinity. º
Over much of Nebraska and even close to our southern border there are
quite deep deposits of volcanic “ashes” or dust, such as is carried in the
air sometimes hundreds of miles. The substance is a pulverized glass as
fine and white as flour. The deposit is in Pleistocene deposits and proves
that some great volcanic outburst occurred at that time. The location of
the eruption has uot yet been discovered.
cHAPTER Ix.
GEOLOGICAL HISTORY OF SOUTH DAKOTA.
Having finished our review of the various geological förmations found
in our State, it will be both helpful and interesting to give an interpreta-
tion, making only brief references to that of others, wherever there may be
variances. The record is, at various points, so imperfect and the princi-
ples of interpretation so change from time to time, that no two of the stu-
dents of the subject have agreed on every point, and in some places their
conclusions are diametrically opposed.
It is generaly believed that at an early stage the earth was a sphere
composed of, or at least covered with, molten rocks and the oceanic
waters and other volatile substances were suspended in a gassy state
above its surface. As the heat was radiated into surrounding space, a
crust formed over the molten surface, and in time the waters suspended in
the atmosphere took their place as the ocean, which was at first doubtless
shoreless. The first dry land is supposed to have been the result of fur-
ther cooling and the consequent crumpling of the earth's crust by the
shrinking of the whole mass within, to such an extent that a portion of the
crust was thrust out above the water. We have no evidence of there be-
ing any portion of this first crust now exposed in our State. In fact, it is
very doubtful whether such is found anywhere on the earth's surface.
The schists and slates of the Black Hills were probably first formed as
clay and muddy sand in the primeval ocean. The material was derived
probably from ancient land to the west or possibly northeast of that
locality. They were composed, as we have seen, of unknown thickness.
The early crust of the earth, because of its thinness and the probable
greater activity of the disturbing forces, is everywhere found very much
folded and crumpled, and the rocks are mingled in a confused mass with
molten material, which apparently rose from below and in some cases not
only penetrated but overflowed. So in the Black Hills the slaty cleavage
seems to have been formed in harmony with, and probably attending, the
outflow of the Diorite which has been described. At the same time parti-
cles of the slates and schists were changed from their fragmentary char-
134 GEOLOGY OF SOUTH DAKOTA.
acter of clay, sandstone, and limestone into the crystalline, condition of
schists, slates, quartzite, and marble. These folds were probably at first re-
latively much higher than now. We have only the stumps as it were of
the original sharp folds. There may have been lava outflows spreading
over the surface but they have long since been carried away.
Later the granite was similarly erupted. It was no doubt cooled far
below the surface and under pressure. The coarse structure indicates
that it cooled very slowly as it would under such conditions. The ma-
terial of the granite may have been derived from the melting and incorp-
orating into itself portions of the schists and perhaps other rocks underly-
ing them. The exposure of the granite indicates that several thousand
feet of rock have been carried away by erosion which formerly lay above
it. It now rises 7,000 feet above the sea. In those early ages it may A
have been 6,000 or 10,000 feet lower with reference to the sea level.
That the granite succeeded the outflow of the diorite is indicated by the
diorite never cutting through the granite veins while the opposite is true
of the granite.
Toward the end of Archean time, the Black Hills stood as a high
rugged Island, probably considerably higher, relatively, than at present,
in a shallow sea in which there was no life. Away to the northeast was a
similar and larger land-mass occupying central Minnesota and extending
eastward to Labrador, also north and northwest from that point past the
Lake of the Woods to the Arctic Ocean. Several more or less continuous
ridges probably at the same time occupied the Rocky Mountain region.
The ocean surrounded all and lay over the eastern part of our State ex-
tending into southwestern Minnesota. In it gradually accummulated,
from the adjacent Minnesota land, through the action of waves and tidal
currents, extensive beds of sand and sandstone, at least a few thousand
feet in thickness. As is commonly the case under such conditions, the in-
crease of the burden weighed down the comparatively thin crust of the
earth underneath, so as to receive these thousands of feet of sediment
without appreciably filling the surrounding sea. The western end of the
State not only suffered great erosion meanwhile, but gradually began to
subside while the eastern end held its own and perhaps began to rise.
In the Potsdam Period, the subsidence of the Bleak Hills region went
on steadily while the waves cut down its shore and spread the material
over the surrounding sea-bottom. In this was deposited the Potsdam
sandstone which near the Hills is from 200 to 300 feet in thickness. It
seems not to have entirely covered the Archean nucleus until the end of
that epoch. The Minnesota land had at some time thrust out a peninsula
toward the southwest into our territory so that we find no Potsdam sand-
stone exposed at that end of the State. During the Potsdam, abundance
GEOI,OGY OF SOUTH DAKOTA. 135
of low forms of life were found in the sea and fragments of their remains
are very abundant in some strata in the Hills.
This phase of the seesaw movement between the two ends of our State
seems to have continued through the Silurian and Devonian. The few
feet of Trenton limestone of the clays which lies above and below seems
to mark the time when the Black Hills were so low below the sea that the
action of waves and currents failed to deposit any considerable amount of
material. It is an interesting problem not yet investigated, whether there
are not in the 25 or 30 feet of greenish clay between the Trenton lime-
stone and Carboniferous traces of a deep sea formation similar to that dis-
covered and described by the explorers of the Challenger Expedition in
the abysmal depths of the Atlantic and Pacific. It seems not necessary
to suppose that great depth existed, nor that the area was very remote
from any land, but rather that it was not in the path of ocean currents
nor much affected by tidal action. The latter consideration must probably
be given great importance for the area could not have been more than
200 miles from land toward the east and possibly not toward the west or
northwest. But it may have been so related to the shores what currents
did not transport much material to that locality. It may have had some
such relations as the “Bottomless Pit,” in the Bay of Bengal.
After remaining in this condition through the Silurian and Devonian a
change of oscillation brought it near enough to the surface in the early
Carboniferous for the flourishing of invertebrate life from which were built
the several limestone beds of the Black Hills. At that time the relation
may have been like that of areas in the Pacific ocean, where coral islands
abound, although remote from extensive land. Toward the end of the
Carboniferous the sea had evidently become so shallow that the action of
the waves and the possible approach of the shore produced extensive beds
of sand.
The eastern half of the State, meanwhile, was dry land with perhaps
slight extension farther west. The east shore line must have crossed our
state near the middle from north to south. A very interesting corollary
follows from this conclusion. Namely, that considerable beds of Carboni-
ferous coal may occur within our borders. For on general principles and
from analogy with similar conditions elsewhere, we should expect that
along the shore, which we have every reason to think was sloping very
gently westward, there were likely to be formed marshy areas similar to
those which produced the coal beds, so well known in the eastern part of
the Mississippi Valley. Certainly the climate and the character of the
vegetation and extent must have been nearly identical with those farther
east. That there were no rapid changes going on may be inferred from
the facts already mentioned in connection with the Black Hills region.
136 GEOLOGY OF SOUTH DAKOTA.
Therefore everything seems to have been favorable for the growth of
luxuriant Carboniferous plants and we see no reason why they should not
have formed beds of coal. There is however one apparently insuperable
obstacle to their being utilized, namely, that they lie below the copious
flood of artesian waters. Should it be found that there are local disturb-
ances in the region south of White river within our border we may expect
that portions of Carboniferous strata, including coal, may be discovered at
no great depth below the surface. In favor of this view may be men-
tioned the fact that several distinctly Carboniferous fossils are said to have
been collected near Gordon, in Nebraska.
Toward the close of the Carboniferous the action of the waves and
currents was felt again, indicating that the sea was shallow. We do not
find clear evidence that any portion of the Black Hills appeared above
the sea in that age. The curve of the upper Carboniferous strata would
carry them nearly if not quite over the summit of Harney Peak and other
Archean rocks. The principal considerations pointing to the opposite
view is the difficulty of accounting for the abundant material which was
deposited during that epoch, over the Black Hills. Further study may
reveal the fact that there was sufficient elevation to raise the lower Car-
boniferous and possibly Archean rocks higher than those now in existence
above the sea, or to such a height that they furnished abundant material
for the later beds.
During the Triassie the whole western end of the State, with the whole
region of the eastern slope of the Rocky Mountains, seems to have been
shallow sea and barren of life. This may have been the result as before
noted, of either the separation of the inland sea from the ocean by a barrier
in the southern part of the Mississippi valley, or as Dr. Carpenter suggests,
the abundant igneous outflows into this wide basin were sufficient to so
poison the waters that they were hostile to life. The difficulty with the
latter supposition is twofold: First, there is no clear evidence of exten-
sive igneous outflows within the basin; second, that from the comparison
with seas surrounding volcanic regions as in the East Indies, there seems
to be no markedly injurious effect upon the animal life, at least not to
such a degree as to render it entirely extinct. We therefore favor the
former support supposition although there is no clear evidence of its cor-
rectness. During this time, the eastern shore of the sea lay probably far
west of the Missouri through our State, Nebraska and other States farther
south. At the time of the Purple Limestone it seems to have been so
condensed that it deposited carbonate of lime as a precipitate. Both be-
fore and after it probably deposited together with the clay, much rock-
salt and gypsum, as we have elsewhere argued.
At the beginning of the Jurassic there seems to have been a connection
GEOLOGY OF SOUTH DAKOTA. . 137
with the outer ocean and influx of forms of vertebrate life. The sea was
shallow as is shown by the ripple marks and the nature of the deposit. It
will be remembered that vertebrate life had attained great development
of reptilian forms, the most gigantic lizards that the world has ever seen,
(Atlantosaurus) having flourished at that time. Its thigh bone was six
feet long and the estimated length of the animal was 80 feet. This
change indicates a disturbance in the earth's crust. By reference to our
chart of geological formations at the end of this volume, it will be seen
that no trace of Early Cretaceous rocks are yet to be found in our State.
The Black Hills were at that time dry land, the shores of which were so
remote from their center that any formation then produced has been en-
tirely covered up by the easily recognized formation at the base of the
Later Cretaceous, namely, the Dakota sandstone. With the Later Cre-
taeedus there seems to have been an advance of the sea quite rapidly to-
ward the east and also around the Black Hills caused by a general sub-
sidence, so that before the close of the Dakota period the whole of our
State was covered by the waters of the ocean. In the earlier quiescent
stages of this advance there seems to have been in the shallow basin south
of the Archean peninsula extensive marshy areas in which beds of lignite
were formed such as we have mentioned in the vicinity of Centerville and
at Ponca, Nebraska. At nearly the sametime, deposits of the same sort
were forming around the Black Hills. The layers of lignite near Rapid
City and in the southern part of the Hills also indicate this. On New-
ton's map attending the geology of the Black Hills, “coal” is marked in
the Dakota area at the north end of the Hills, although no reference is
made to it in the descriptive text. The deposits of coal at Cambria and
Newcastle, Wyoming, on the west side of the Hills have been found to be
in the early Dakota. It is probable that the western slope of the Black
Hills uplift was more gentle and therefore favorable for the formation
of marshes; yet we know no reason why it should be more so than on the
north and south of the Black Hills. Attending this advance the action
of waves and currents formed the extensive beds of sand now constituting
the Dakota sandstone and during the quiescent stages of the advance,
which was of an oscillatory character, extensive sheets of clay were also
deposited alternating with the sand.
In the Black Hills region the dome-shaped uplift became more marked
and began to be attended with slow subsidence in the surrounding vicin-
ity. According to Newton, the Hills were covered by the sea and the
successive formations of the Upper Cretaceous were formed over the
whole area as late as the Fox Hills epoch, but here again we are met with
the difficulty of accounting for the source of material. Both for this
reason and from the character of the Dakota sandstone, which contains
138 GEO LOGY OF SOUTH DAKOTA.
pebbles of Archean rocks, we judge that the Black Hills uplift was an
island in the sea. Meanwhile, as before hinted, the rest of the State was
slowly subsiding, possibly with local folds, so that the portions of Dakota
sandstone were elevated above the sea at one time and again submerged.
In this way we may perhaps account for the occurrence of Niobrara
“chalkstone” on the same level with the Dakota sandstone, as in the vicinity
of Mitchell. The eastern shore line of the sea at that time was probably
far east of our State. The Benton and Pierre clays are such as might
have been deposited in a shallow sea far from land, the shores of which
were the scenes of active erosion. The Niobrara “chalkstone '' was
probably formed about the time of the maximum extent of the inland sea,
when the central portions would be farthest from land and at the time
when the products of erosion were less abundant and therefore the waters
more clear. This would be favorable for the formation of extensive
Foraminifera beds in the deeper areas, and of oyster-like Inoceramus
beds near the shore. The sea was retiring, doubtless, during the Pierre
epoch, mainly toward the north, and the Fox Hills stage, probably
marks the time when its waters had become so shallow that waves and
currents assorted the material and removed the finer portions. At the
close of the Fox Hill, the sea retired from our borders toward the north,
never to return. * *
In the Laramie epoch, as would result from this change, the slope of
the newly formed land area would be gently toward the north, and exten-
sive fresh water delta-like formations accumulated over the northwest-
ern quarter of the State, while the deeper beds of the time were formed
north and west in Montana. That was an age of extensive marshes and
abundant growth of vegetation, both of pines, deciduous trees and palms,
from which have been formed the numerous, extensive, and often times
thick beds of lignite, which occur in North Dakota, Montana, Wyoming,
etc. Over the extensive marshes there roamed strange reptiles, creeping,
swimming and flying, with a few marsupials, foreshadowing mammals of
later ages. During this time occurred the extraordinary volcanic out-
bursts, which affected principally the north end of the Black Hills, and as
a result of which we have the high and picturesque peaks that we have
already described. It is not improbable that the disturbance at the east-
ern end of the State may have occurred at about the same time. This
disturbance is but one manifestation of many similar eruptions which took
place in other parts of the earth about the same time.
Following this was the Eocene epoch when we may suppose that our
State was clothed with luxuriant vegetation, supplied with abundant
moisture and peopled with strange gigantic mammals. Of this we have
little or no record within our borders. We simply know that the Black
GEOLOGY OF SOUTH DAKOTA, 139
Hills were relatively quite prominent and streams of considerable size
radiated from them, as at the present time. Instead, however, of ex-
cavating narrow and deep valleys, they flowed with gentle currents
and broad channels out across the plains and deposited considerable
areas of gravel from the Black Hills. The record of life of these times
is lost from our State, because, as is well understood, remains of life,
either vegetable or animal, are not preserved except by being buried,
either by aqueous or igneous deposits. The history of this time is well
recorded in the Eocene beds about the Uinta Mountains. It may be that
more careful examination will reveal some valuable pages in this history
of life, within our own border. \
At the beginning of the Miocene, we find that a change has taken place,
affecting particularly the Rocky Mountain region by which the area
around the Black Hills, particularly toward the south and east, became
occupied by a vast shallow fresh water lake. We have seen how these
lakes have supplied wonderful, and wonderfully abundant, remains of
strange vertebrate animals. It is not improbable, as we have already
suggested on a previous page, that it was a time of storms, earthquakes
and possibly of volcanic outbursts and eruptions. The Black Hills, shar-
ing with the same movement which affected the whole Rocky Mountain
system, kept on steadily rising; the lake shifted more to the east and
eventually seems to have drained away towards the south. The streams
were quickened in their action, the moisture probably increased about
the Black Hills because of their greater elevation and the increase of evap-
oration over the plains. As a result there was a great erosion of the Miocene
beds over their whole area particularly near the hills and along the chan-
nels of the principal streams. As the slope of the streams was slight, com-
pared with the present, their valleys, except toward the east, were prob-
ably not deeply excavated.
Then followed a gradual upheaval as is indicated by various buried
channels and the accumulation of ice in the northeastern portion of our
continent. This advance during the later stages of the Tertiary deepened
the valleys of the streams in the eastern part of our State. Toward the
close of the Pliocene, the streams like the Grand, Cheyenne and White
rivers had cut down 100 to 200 feet below the general level of the sur-
rounding upland, and at that time more than that amount above their pres-
ent beds. The Missouri (or James river) had cut fully down to the pres-
ent level of the James, and the Big Sioux, probably as deeply, if not lower
Thus far we have seen nature preparing the foundation for our land;
the separation of the ores for the miner; the storing of coal for fuel; the
distribution of various ingredients valuable to agriculture, and also re-
cording more or less completely the wonderful advance and multiplication
of forms of life. We now come to a time when the finishing touches were
140 GEO LOGY OF SOUTH DAKOTA.
put upon the earth to prepare it for the abode of nature's highest work-
manship, intelligent man.
The work so far as our State is concerned began with the increase of
inclement weather, cold and moist. This was the result of the elevation
of the region northeast, and accumulation of ice, already mentioned.
As we have briefly described, the ice made its entrance from the north-
east by way of the Red River Valley over and through the narrow divide
into the James River Valley, then occupied as we believe, by the Missouri
river. As a result of this displacement of the Missouri, there was formed
for a short time a great fresh water lake, which we have called for con-
venience, Lake Arickaree. This was formed north of the extension of the
Fox hills eastward and which has since been cut through so as to form the
present channel of the Missouri, near Forest City. In a similar way a
large fresh water lake, which we may call Red lake, was formed north of
the Bijou hills; and also in a similar way the divide between the White
river and Niobrara was cut through west of the Bijou hills, and for a time
a steep rapid was formed a little farther south, near Platte creek, where
the waters probably entered a tributary of the Niobrara. The ice mainly
filled the valley now occupied by the James river and pushed its sluggish
mass, as we have described on a previous page, to the vicinity of
the Missouri river, at several points; namely, Walworth, Pierre, Lake
Andes, Running Water and Vermillion. It seems probable also that
toward the south it may have gone beyond the present location of the
Missouri for a short time; so also in the east it may for a time have cov-
ered the East Coteau.
Then came as is believed a melting of the ice and the formation of the
Loess deposit in the lake-like streams flowing from the southern edge of
the ice sheet. The melting, however, was shortly arrested and the ice
flowed steadily bringing its debris from the northern rocks, over which it
passed, and built along its edge the First Moraine whose location has al-
ready been given. o
ſ The peculiar bend in the Big Sioux river by which it was thrown over
;the quartzite at the Falls is to be referred to the presence of the ice sheet
'immediately south at this stage. Sioux Falls and the region north and
east was frequented by mammoths, and possibly a timbered region, while
Canton was covered several hundred feet deep with ice.
It is supposed that this melting ice and recession was partly the result
of, the subsidence of the highland from which the ice streams radiated.
We need not dwell upon the different stages of recession and the tempo-
rary advance and formation of the successive moraines which we have al-
ready located and described on preceding pages.
The beautiful and wonderful planning, and scoring of the red quartzite
at many points in Minnehaha county are to be referred to the action of
* I
GEOLOGY OF SOUTH DAKOTA. 141
f
the ice before the moraine was formed, but similar work southwest of
Bridgewater, west of Salem and at Rockport, was finished much later.
When the ice occupied the fourth moraine there was formed in the
James River Valley from the fourth moraine southward to the vicinity of
Redfield, and possibly as far as Mitchell, a long shallow fresh water lake,
Lake Dakota, which became filled with loess-like silt forming the re-
markable level plain now occupying that region,
Meanwhile the Black Hills were the recipients of great rains as would
appear from the continued transfer of gravel and boulders from the Hills
over the surrounding region, particularly along the valleys of the Chey-
enne and its tributaries. This was the time of the formation of those
great terraces along the valleys of the Cheyenne and Missouri rivers,
which we have already described. It is probable that the plains were oc-
cupied by numerous mammoths and mastodon, possibly herds of buffalo
and antelope, wolves, horses, etc., during the epoch of the Ice Age.
Traces have been found of more abundant vegetable growth. Several
cases of buried trees have been reported from Douglas and Charles Mix
counties. In a well near Andes creek two or three miles north of Grand
View at a depth of 20 feet from the surface, a layer of peat nearly a foot
in thickness was found. Numerous fresh water shells and a log with
cones resembling, if not identical, with those of the tamarack, were mingled
with it. The character of the deposit above, with the surrounding topog-
raphy indicate, that there had been a marshy basin in the Drift in which
the tamarack had grown for many years, when by some change of the
climate, and possibly a change of the course of Andes creek near by, filled
it with fine silt and clay to the depth already stated.
Some of the benefits of the Ice Age may be briefly enumerated as fol-
lows: It gave a beautifully varied and yet even topography which is
found in the eastern part of our State; it mingled the various ingredients
of the rocks over which it passed and produced the uniform and rich soil
which is characteristic of the whole region east of the Missouri.” It pro-
duced at many localities beautiful lakes, not only for the ornamentation of
the landscape, but for the storing of moisture in our region. Several of
these have become known as summer resorts. By the same influence the
picturesque terraces were formed along our streams which are found so
admirable both in appearance and healthfulness for the location of towns
and cities. The convenient storing of subterranean waters, also, has been in
many cases perfected by the work of the ice.
As the ice receded and the Rocky mountain system gained somewhat
greater altitude, the humidity of the region diminished and the climate
became more like that of the present. At the same time the vegetable
and animal life gradually changed from forms, which we have briefly
mentioned as then existing, to such as are now natives of our State,
CHAPTER X.
ECONOMIC GEOILOGY.
It is difficult to say what portion of Geology may not have an economic
bearing. Although many investigations have been pursued in the pure
love of knowledge they have often unexpectedly led to economic results
of great value. Even a study of fossil forms, which may have been be-
gun with a spirit of curiosity or love of acquisition of rare forms, has been
of invaluable aid in determining the existence or absence of coal and
other mineral products. In this chapter, however, we shall confine our-
selves to the presentation of such facts as are clearly seen to have eco-
nomic bearings. We naturally take up the various products in the order
of the geological formations in which they are mainly found. This will
also lead us to consider first the mineral ores and later building materials,
cements, etc.
MINER A L ORES.
Gold:—Gold stands at the head of the precious metals, not only in
value but in the amount produced in our State. Prof. W. P. Jenney
enumerates the methods of occurrence of gold in the Black Hills, as fol-
lows:
“1. In veins of ferruginous quartz traversing the Archean schists and
slates.
“2. In strata of slate mineralized and altered by the action of waters
depositing silica and iron pyrites.
“3. In conglomerates forming the lower layer of the Potsdam sand-
stone, resulting in this case from the denudation of ledges in the Archean
rocks.
“4. In trachyte and porphyry.
“5. In deposits of slates and sedimentary rocks, produced by the in-
trusion of the trachyte and porphyry.
“6. In placer gravels, resulting from the decomposition and erosion
of the above formations in the Tertiary and recent times.” (Geol. Black
Hills, p. 225.)
In enlarging upon these different forms of occurrence we are chiefly in-
debted to Prof. F. R. Carpenter, who has made a more recent and careful t
study of them. His results were published in his “Report of the Geology
and Mineral Resources of the Black Hills,” already mentioned.
· KJLIO CIVGII “STTIIN (INY GINIIN STYIVISTIKOH GITII–， AI GILYTAT

GEOLOGY OF SOUTH DAKOTA. 143
!
First. Of the gold in quartz veins he says: “It is accompanied by
little or no sulphur but occurs free in the vitreous quartz, often in quite
large pieces.” (Geol. and Min. Res., Black Hills, p. 121.) As has been
stated elsewhere these veins occur more or less throughout the whole
Archean area, and not only cut across the bedding, but perhaps in the
majority of cases lie parallel with the schistose and slaty structure. They
are often times very rich.
Second. Of the second class a more notable example, as he considers,
is the Homestake vein which is sometimes spoken of as the “Belt.” This
feature comprises a ‘section 6,000 feet long by 2,000 feet broad upon
which several mills are located.” (Geol. and Min. Res., Black Hills,
113.) He says further, “The ‘ore’ is not continuous throughout this dis-
tance, (6,000 feet) but occurs in shoots or vast “pipes,” lenticular shaped
in cross section. The beds of argillites, phyllites and amphibole schists,
in which shoots occur, have a strike of nearly 37% degrees west, which is
also correctly the strike of the plane of the ore channel in which these
shoots occur. The dip of the beds, as a whole, is toward the east. The
shoots dip east also, upon but athwart this plane, at an angle of about 45
degrees, . The ore and in closing rocks have indifferently the same gen-
eral cleavage structure.
“In the Homestake proper, in the south end of the Belt there are nu-
merous sheets of porphyry, or more properly, of felsite, sometimes cutting
across the stratification, but usually parallel to it. In the northern half—
that is, the Deadwood–Terra and De Smet end—no porphyry is found in
the vein, but the section was once overlain by a felsite, which yet remains
as a capping to the ridge between Gold Run and Bobtail Gulch and be-
tween Bobtail Gulch and Deadwood Creek. This porphyry was injected
between the slate and the Potsdam, raising the latter and other overlying
rocks after the manner of laccolite, though they have since been removed
in the immediate area. The vent through which this sheet was injected
had probably no connection with the small dikes found in the Homestake
but was intruded from the southwest and most likely was connected with
the igneous mass forming Terry's Peak. e
“The percentage of pyrites impregnating the slates and schists and
forming the “ore ” is never large. The yield upon concentration is
seldom 20 per cent. The average is not more than 7 per cent. There
are no solid bodies of pyrite.
“The influence of the porphyry upon the lode, seems to be good, but
whether in produce an enrichment of the bed, or whether it rendered it
by some action of oxidation, or otherwise, more free-milling has not yet
been determined definitely. The fact, however, is that the Homestake
yield per ton is much greater than that returned by the Deadwood-Terra
and other claims, where the igneous intrusion do not occur, the former,
from the best attainable data, being $3.87 per ton, while the latter lies
between $2.03 and $2.82. The sheets of igneous rocks in the Homestake
are porous and much decomposed. Careful assays showed no gold. The
sheets east of this, near the pump shaſt, are pyritiferous and assay from $1
to $2 per ton. From what we have stated, I am led to the conclusion
that the porphyry is of two-fold benefit.
First. It renders the ore more free milling.
144 GEO LOGY OF SOUTH DAKOTA.
}
*
Second. It has, in the neighborhood, produced either enrichment of
the deposit, or a further concentration of what gold originally existed
in it.” *
“That it was gold bearing before the injection of these dikes is proven
from the fact, that remote from their influence it is gold bearing, and that
all similar beds through other parts of the Hills, where no igneous rocks
occur, are also gold bearing, as well as from the evidence furnished else-
where from the study of the Potsdam conglomerate, which as has been
stated was laid down prior to their injunction. At the surface the ore
has always appeared in shoots, as I have described, but I am credibly in-
formed that in the deeper works of the Homestake end this is no longer
the case, the bed being now continuously of the ore bearing for many
hundred feet. These ore bodies are said to have exceeded 300 feet in
thickness. Careful measurements of the big open cut upon the Golden
Star claim gave as the cross-section of that body, 150 by 350 feet, while
the Terra cut gave 150 by 250. These figures are probably correct, so
far as the width is concerned, but the shoots may be longer.” t
Prof. Carpenter considers that the Homestake was originally laid down
as a stratified or bedded deposit and that it appears to have been subse-
quently modified by infiltration and that the latter change also occurred
in Archean times.
Prof. Crosby in speaking of the deposits of gold attending the porphyry
outflows elsewhere, remark: (p. 515.)
“Whether the gold of the Homestake and other mines, situated in the
ferruginous slates and schists of the newer Archean series, is derived from
the associated porphyry dikes is an entirely independent question. Prof.
Carpenter has answered it in the negative; and he is certainly justified,
in the main, by the fact that similar ferruginous strata are distinctly
auriferous outside the volcanic area. Still, after studying the Ruby Basin,
it seems impossible to resist the conclusion that the porphyry is the ac-
tual source of some of the gold in the Homestake district; although its
chief favorable influence has probably been to render the gold originally
present more available.”
Third. The third class of deposits, namely, in the Potsdam sandstone,
are considered by all who have studied them to be really ancient placers,
formed by the action of waves. These mines are known as “cement
mines” because of the consolidation of the conglomerate by the cement-
ing material. The gold in these cement beds is mined, stamped and
amalgamated as other free milling gold ore. The cut presented, taken
from W. P. Devereaux’s paper “On the Occurrence of Gold in the Black
Hills” (Proc. Am. Inst. Mining Engineers, Vol. IX, p. 465; quoted by
Carpenter) shows well the relation of these Potsdam placers to the adjacent
formations. The Archean schists lie below and their uneven surfaces show
much erosion. The porphry, while sometimes capping the Potsdam is
elsewhere injected underneath or within it; at other points it lies between
it and the Carboniferous rocks above.
GEOLOGY OF SOUTH DAKOTA. 145
ZEºſ Cº.
sº tºº ºw
sºlºlº
aſſº
F---------
&=s Blacktail
Sºº-ºº: : ---
amº ºx º' —ºº::==
====
* = s
#Porphyry #Potsdam
Approximate Geological Sketch from Hornestalze Vein, Eastward.
f FIGURE 2, *
“The drawing represents the section taken perpendicular to the Home-
stake, and extends about 1% mile to the east. The lower contact line is
the ancient Potsdam beach. The later placers occupying the gulches be-
neath derive their gold mainly from the disintegration of the overlying
Potsdam; and while Deadwood Gulch has received additional gold di-
rectly from the Homestake deposit, Black Tail Gulch lying at the base
with Deadwood creek, between it and the Homestake contains no gold
that comes directly from this deposit. What it contains has come through
the medium of the Potsdam.” (Geol. and Min. Res. Black Hills, p. 112.)
Mr. Devereaux, who had the management of some of these cement mines
noticed that the gold in these conglomerates, is finer than the gold of the
Homestake, whence it is derived. Since it was set free, it has been sub-
jected to various chemical agencies which have dissolved out a part of its
silver alloy. This solution of the silver, having been confined to the
surfaces of the pieces of placer gold, has given them a corrugated appear-
ance, and this being true, it follows that the smaller the pieces are, the
finer gold. The average of Mr. Devereaux's assays gives the following
fineness: Gold, 904; silver, .096; while from assays made by Mr. George
Hewitt, the different ores from the Homstake yield gold as follows:
(Geol. and Min. Res., Black Hills, p. 112.)
Homestake. Highland. Terra. Deadwood. | De Smet.
Gold ---------- .82O .83O .825 ,850 .82O
Silver --------- .17O . I 55 .16o ..I4O ..I'70
4. Concerning the existence of gold in the porphyry the evidence is less
distinct. We have already noted the statement of Prof. Carpenter that
gold was found in the porphyry attending the Homestake lead. Prof.
Jenney in his report, says that as gold has been found in the trachytes of
the Bear Lodge range, he considers its occurrence in the igneous rocks
of the region of Terry Peak extremely probable. Because the origin of
the present mineral deposits has been traced to hot waters attending the
igneous outflows, it is not improbable that siliceous precipitates may be















IO
146 GEOLOGY OF SOUTH DAKOTA.
contained in the igneous rocks, as well as in the metamorphic rocks ad-
jacent.
5. Deposits of the fifth class are found in the Paleozoic rock in Ruby
Basin and Bald Mountain, at Galena and Carbonate. Of these Prof. Car-
penter says: (Page 124.)
“The former are mainly gold bearing while the latter yields silver and
lead. They cover a large area, larger as I shall presently indicate than is
generally supposed, and must soon become important ore producers. The
ore-bodies are not continuous, but occur in shoots. In the first mentioned
districts, the shoots have great linear extent and are usually from 40 to 60
feet wide, and while some are less than this, others again are greater.
They vary in thickness from a few inches to 10 feet or more. Many
hundreds of claims showing minerals have been staked and recorded. The
value of the ore varies. Some of the ore-bodies will not average $15,
while others exceed $60 per ton. From $20 to $25 may be taken as a
fair mean.” # * *
“At Galena the ore bodies are of equal promise but of a different char-
acter, being silver-lead instead of gold. * *
“These ores are found only in connection with the igneous intrusions.
The gold ores are found in the vicinity of Terry's Peak and Bald Mount-
ain, where outliers of Potsdam rocks yet remain. Inference is fair that
the rocks once connecting these outliers were also mineral-bearing, and
that, in the Potsdam beneath the unremoved Carboniferous beds, will be
found ores also, at least so, far as igneous intrusion continues. * *
“At Galena the miner sees only the outcrops of these ores. They
dip eastward with the inclosing rocks at an angle of 16 degrees from the
horizon. After leaving Bear Butte creek no other stream cut through to
the level of the mineralized portions. * *
“North and south of Bear Butte creek there is an area of nearly 50
square miles, where the igneous rocks occur in exactly the same relation
to the Potsdam, as at Galen.a. The streams of this area sometimes cut
through to the igneous rocks between the Potsdam rocks enabling one to
see this relation, while vertical dikes rise in many places to the surface.
I believe that shafts, sunk to the Potsdam anywhere in this section, would
be likely to intercept ore. West of Terry's Peak and Bald Mountain,
the same condition occurs, throughout a much larger area, extending to
the Wyoming side of the Hills, where similar ores are known to exist.
After a thorough examination I am convinced that not a tenth of the area
in which these ores occur has yet been located.”
He remarks further with reference to the method of formation: (p. 127.)
“These occur principally along the bedding planes of these rocks, but
deposits are also found occupying the vertical joint planes as well as im-
pregnating the quartzite by replacing the cementing material of the orig-
inal sandstone. They are found in such close relation with the igneous
rocks that the conclusion is irresistible that they owe their origin to these
rocks.” *
“At Ruby Basin and Bald Mountain they usually occur as impregnating
distinct zones of the quartzite, and occur at different levels in the rock.
GEOLOGY OF SOUTH DAKOTA. 147
The most favorable position seems to be upon or in, the upper part of the
quartzite, forming the basal member of the group. Owing to the removal
of overlying rocks, many of the ore-bodies are so thinly covered, that the
original pyrite has been oxidized. That this oxide, now forming from 10
to 20 per cent of the ore-body was derived from the pyrite there seems
to be no doubt. In the deeper workings a peculiar bluish quartzite con-
stitutes the ore. Under the microscope this is seen to be composed of
rounded grains of silica, imbedded in the silicious paste, which carries a
very finely divided iron pyrite. This silicious paste with the pyrite clear-
ly occupies the spaces between the grains of quartz, which composed the
original sandstone and was deposited metasomatically, replacing the for-
mer calcareous cement. That is, particle by particle as the original ce-
ment was dissolved out, it was replaced by the silica-pyrite cement. The
solutions which wrought this change brought also the gold and silver,
From the description I have given it will be seen that these deposits did
not, in the ordinary sense, fill pre-existing cavities.”
“These ore are, in some sections, almost exclusively gold bearing, in
others partly gold and partly silver, and again in other places the silver
predominates. They fill not only the places between the quartz and
grains, but occur in large bodies, replacing the beds of lime shales some-
times occuring in the Potsdam. This last is the mode in which the de-
posits at Galena occur. It would seem as though the porphyry at Bald
Mountain brought mainly gold; at Ruby Basin, a few miles distant, gold
and silver in equal quantities, while at Galena, 12 miles distant, silver-
lead predominates. In the same section the proportion of gold is greater
in the lower contact while in the upper it gives place to silver. That is,
briefly speaking, gold predominates in the quartzite, but gives place to
silver as we approach the more calcareous portions, forming the upper
part of Potsdam; while in the massive limestone such ore bodies as are
found, like the Iron Hill, are exclusively lead and silver, notwithstanding
that the porphyry is in all instances the same.”
Sixth. The recent placers occur, of course, in the gravels of the present
streams, both in those of the present flood plains, and those occupying ter-
races of older origin. These in the Black Hills, as in most other gold
bearing regions, were the first discovered deposits of gold. Much of Prof.
Jenney’s report on the Geology of the Black Hills, treats of the placers
as they were found in nearly all streams of the Hills.
The first discovery of gold by white man was on French creek early in
August, 1874. Placer mining has nearly passed by, and most of the gold
of the present time is derived from the large, though comparatively lean
mineral deposits, like the Homestake lead. Occasionally very rich de-
posits of gold ore in quartz veins are being continually found. The pro-
duction of gold in the Black Hills for 1892 was $3,700,000; in 1893, $4,-
000,000.
Gold elsewhere in the State. From the history after the glacial deposits
it is not very improbable, that slight traces of gold may be found in the
glacial drift. A few years since such finds were reported upon the East
148 GEO LOGY OF SOUTH DAKOTA.
k
Coteau. The recent discoveries of gold near the Lake of the Woods and
near Redwood Falls, in Minnesota readily explain such occurrence. The
finding of a few grains however should not arouse great hopes of valuable
placers.
SILVER.
t
Ores of this metal occur either in connection with gold or lead, and as
reference has already been made to its ores in connection with the gold,
we need not repeat at this point. The amount of silver produced in South
Dakota in 1892, was $75,119; in 1893, $181,527.
COPPER. t
Of this metal Prof. Carpenter says: (p. 122.)
“The copper deposits are numerous and extensive, but undeveloped.
They are found in both the eastern and western portions of the Archean
rocks, the richer being apparently in the latter. They show a copper-
stained gossan, from 50 to 500 feet in width. Where the outcrops, or
backs of these ores disappear beneath the Potsdam, it also, is copper-bear-
ing, clearly deriving this metal as a secondary deposition from the beds
below.
“At the Blue Lead there is a great quantity of these gossan ores. In
sinking through them the miners reach a leached, decomposed portion of
the bed, but no one has yet gone far enough to tell what lies below this.
Doubtless they are identical with the famous Ducktown deposit. (p. 122.)
“There is enough of this surface copper, which consists of malachite,
red oxide, native copper and copper glance to justify the erection of a
water-jacket smelter at some convenient point. The average per cent of
these ores as assayed by the School of Mines, is about 35 per cent copper,
equal to 700 pounds of metal copper per ton, worth at present rates,
$112.”
LEAD.
Around Galena, as has already been stated, silver-bearing galena is
found in paying quantities. About Carbonate the ore is principally ear-
bonate of lead and silver.
IRON.
The iron ores found in the Black Hills have not been developed. Prof.
Winchell, in his course down Box Elder creek (Black Hills of Dakota,
Ludlow, pp. 52 and 53), records the occurrence of extensive deposits of a
silicious iron ore in the Archean rocks. In some cases, it apparently at-
tains a thickness of over 50 feet. There were hills of it, Newton
calls attention to beds of a similar sort on Rapid creek. Should
easy access be eventually obtained to these beds and abundant fuel be
obtainable from the lignite of areas of the Laramie, these deposits may
eventually prove a valuable source of wealth to our State.
§
GEOLOGY OF SOUTH DAKOTA. 149
MANGANES.E.
Ores of this metal have been discovered at several points in the Black
Hills. In 1892, 19 tons were shipped from Custer county. Assays of
the ores made at the School of Mines have showed 46 per cent of man-
ganese. (Mineral Resources of U. S., 1892)
NICTKEL.
In the pyrrhotite found on Spring creek, 1% to 8 per cent of Nickel
has been found. Similar deposits doubtless occur at various other points
in the Hills. (Carpenter, p. 123.)
TIN.
The universal ore of tin, cassiterite, occurs very generally in the gran-
ite rocks about Harney Peak, and in the northwestern part of the Hills,
known as the Nigger Hill district. The existence of tin in the Black
Hills has been known since 1877, when it was recognized by Prof.
Richard Pearce, of Denver. Previous to that time it had been considered
a troblesome black sand, which interfered with the easy separation of gold
in placer mining. Quantities of “stream-tin” are found in the streams
leading from the granite areas, already mentioned. The discovey of tin
in the native rocks was at the Etta Mine, east of Harney Peak. The
granite rocks seem to contain the tin wherever they are found, but it is
concentrated in certain localities which appear to have a vein structure.
As Prof Carpenter says: (p. 135.)
“These veins have been classed by Newton, Jenney, Blake and others
as igneous or intrusive granites, but they seem to be true veins of a type
known as segregated veins, differing from the true fissure veins in that
they are parallel to the plain of bedding. Usually they are distinctly
lens-shaped.
“Many of them, however, are of the true vein or tabular form and can
be traced for thousands of feet. The Margaret lode can be traced with
few interruptions from Battle creek to Iron creek, a distance of over 6,000
feet.
“The amount of cassiterite present varies. It is never evenly distri-
buted throughout the veins from wall to wall but lies in zones or sheets.
With the exception of being usually parallel to the bedding and not cut-
ting across, these veins have all the characteristics of true fissure veins
and occasionally these features are not wanting, two having been observed
which cut across the stratification.
“The veins vary very much, not only among themselves but even in
the different portions of the same vein. Very often, indeed nearly always
when tin is present, one of the constituents of granite is wanting and the
vein matter is composed of quartz and mica alone, that is greisen, or it
consists of feldspar and mica which for want of a better name has been
called albitic greisen. At other times the veins consists almost entirely of
the massive pinkish feldspar and again not infrequently of quartz alone.
#
*
150 GEOLOGY OF SOUTH DAKOTA.
“The Etta vein is columar, so to speak, in form, it has a cross section
roughly oval of 150 to 200 feet. The arrangement of the minerals is
somewhat concentric. The central portion of the vein is quartzite and
feldspar around which is a zone of albite and mica carrying tin stones in
quite large quantities. Thence comes a zone surrounding these noted
for its large and perfectly formed crystals of spodumene 10, 20 and even
30 feet in length. The interstices between these crystals are filled with
an aggregation of albite, also carrying tin stone (cassiterite), but in a
more massive form than the zone just within. Between the spodumene
zone and the inclosing mica-schist, there is a micaceous aggregate com-
posed of both muscovite and biotite but barren of cassiterite.”
With the tin there is often found more or less of columbite, sometimes
in large quantities. In one locality a mass of a ton’s weight was found.
This mineral because of its resemblance to cassiterite is sometimes mis-
taken for it.
Prof. Carpenter remarks concerning the percentage of “black tin” or
cassiterite in the rock as follows: (p. 142.)
“If all the stuff broken at the mine were sent to the mill the percentage
of tin would be low, if it were closely assorted it could be made very
high, depending entirely upon the extent to which the lower grades of
ore are rejected. Assays signify nothing. Hand samples containing from
25 to 50 per cent black tin, (cassiterite) can be readily selected at any
mine. Prof. W. P. Blake suggests, that it will be probably found advis-
able to send to the mill for treatment all rock carrying 10 pounds per ton
of cassiterite and upwards. If this is done, I estimate two per cent cas-
siterite as a probable average of the tin ores in the Hills.”
According to analyses made at the School of Mines by Prof. W. P.
Headden the tin ore from veins contains 74.5 to 76.7 per cent tin, which
is higher than that from other prominent localities. The analysis of the
Cornish black tin, ready for the market, is about 72.3 per cent. Dr.
Headden’s assays of the stream tin, both from Nigger hill and the south-
ern hills, gives the percentage 72.84 to 73.21 per cent tin. (p. 141.)
The tin ore cassiterite has never been found with free crystaline sur-
faces and is always embedded in the rock. Associated with it are several
minerals of considerable interest. “Great quantities of phosphatic minerals
are found in these veins, including apatite, heterosite, triphllite and
autunite.” (p. 137.)
Graphite is quite a common mineral in the veins, beryls occur often of
large size. Garnets have been found in all mines as far as worked.
Ilmenite, zircons and corundum have been reported.
GRAPHITE.
As already stated specimens of this are found in connection with the
tin ore, but usually not in sufficient quantities to be worked.
GEOLOGY OF SOUTH T) AKOTA. 151
I have been reliably informed that a deposit of considerable extent has
recently been found near Hill City. Analysis at the School of Mines
shows that it contains about forty per cent graphite. the remainder being
of argillaceons and micaceous impurities. It may be found valuable as a
lubricant.
\
MICA.
The granite of the Black Hills in places has its ingredients so large and
coarse that mica of merchantable size is found. Sheets 15 inches in
length are occasionally found and considerable quantities have been sent
to the market. It was in connection with the mica mine that the tin ore
was first found, near Harney Peak, at the Etta mine. Another locality is
found near Custer City.
BUILDING STONES.
Although the Colorado deposits cover much of the State and are largely
free from building stone, important deposits of excellent stone are found
both in the Black Hills, and in the eastern part of the State, in Minnehaha,
McCook and Hanson counties. Besides, stone for rougher work may be
obtained in limited quantities from the Laramie, Tertiary and Drift for-
mations.
GRANITE.
As has already been said the granite of the Black Hills, because of its
coarse grain is more subject to disintegration by weathering. It has not
been used extensively for building and no quarries have been worked. It
is not improbable, however, that the finer varieties of the rock may prove
a valuable building stone. Immense quantities of it are exposed.
QUARTZITE.
The red quartzite, commonly known as the Sioux Falls Granite or
Jasper, is found very extensively in the eastern portion of the State. It
is a most durable rock, and although very hard, natural jointing of
the rock makes it possible to excavate it with comparative ease. It is
composed almost exclusively of quartz, and is usually intensely compact
and hard. Several varieties are found distinguished by different shades of
color, varying from a light pink to a dark Indian red, with shades of
purple. In hardness it varies from the extreme already mentioned, which
is most common, to qualities which have the structure of soft sandstone.
The bedding of the rock is such in certain localities that it is most suitable
for paving stone, but with little difficulty strata furnishing rock of any
size may be found. Extensive quarries have been opened about Sioux
Falls and Dell Rapids. The output for 1892 was valued at $50,000
and that for 1893, $27,828; which shows a decline probably due to
hard times. From specimens at the World's Fair, the report of the
GEOLOGY OF SOUTH DAKOTA.
152
---
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|
|- -


i. GEOLOGY OF SOUTH DAKOTA. 153
Geological Survey and Mineral Resources of the United States referring
to polished samples of this rock, says: “This stone shows occasional
small knots which will not take polish, but this will not seriously inter-
fere with its beauty. The stone, although beautiful enough for orna-
mental work, is at present quarried for paving purposes. The blocks be-
ing used in Chicago where they give satisfaction. The stone splits easily
into paving blocks and it is claimed that it can be worked for this purpose
more cheaply than granite. The crushing strength gave about 22,000
pounds to the square inch. The quarrying of this stone has been going
on for ten years and it is becoming fairly well known to the country at
large as well as to such of the western States as have had practical ex-
perience with it.”
It is a favorite stone for building, the medium varieties being used
for the main walls while the darker and lighter are used for trimming.
It is practically indestructible, although in case of fire it is cracked more
by changes of temperature than granite.
Specimens of this rock found in Minnesota were tested among others from
that State at Fort Wadsworth, Staten Island, under the direction of Gen.
Q. A. Gilmore. For this purpose the rock was dressed into cubes two
inches each way and were subjected to pressure between steel plates, one
direction being perpendicular to the planes of bedding or stratification
and another parallel with the same. The strength shown in the first case
was 27,750 pounds per square inch; in the second, 27,000. This exceeds
that of any other rock from that State, with the exception of the fine
grained syenite from St. Cloud, which stood a pressure of 28,000 pounds.
This rock is found not only widely about Sioux Falls but is exposed
favorably for quarrying in all the northern townships of Hanson county,
where the streams have cut through the drift, and in the valley of Pierre
creek, east of Alexandria. Extensive deposits are found southwest of
Bridgewater and near Rockport on the James river. Iless favorable ex-
posures are found on Enemy creek southeast of Mitchell and two miles
east of Parker on the Vermillion.
Extensive deposits of a somewhat similar rock are found in the Archean
area of the Black Hills. These have been locally used for various pur-
poses, but have not been shipped away,
SA NI)STO N E,
Beds of sandstone are rarely found in the eastern portion of the State.
The most prominent one is three or four miles north of Milltown, on the
James river. It is of a comparatively poor quality, but has been found
serviceable not only for foundation walls, but for the rougher forms of
building.
Thin strata of a rough greenish-gray Sandstone, sometimes hardening
154 GEOLOGY OF SOUTH DAKOTA.
to a quartzite, are found generally in the buttes along the Missouri and
between that stream and the Black Hills. As has already been men-
tioned, a deposit of this rock is found capping the Bijou Hills, Medicine
Butte and others, near White river. The rock in Grindstone Butte is
probably of a similar character. In the western part of the State sand-
stone beds of the Fox Hills are quite frequently found, but their quality
has not been tested.
In the Black Hills there are inexhaustible supplies of sandstone of al-
most any quality or color. The Potsdam furnishes extensive deposits of
the dark brown sandstone of a somewhat different tint, but resembling
the brown stone so popular in the Connecticut Valley.
The Jurassic and the Dakota formation of the Cretaceous are largely
composed of sandstone, as we have already observed. At almost any point
strata may be found of suitable texture either of dressed stone for build-
ing for rougher work, or for fine ornamental carving. At the World's
Fair specimens were presented from the vicinity of Hot Springs, which
showed a remarkable uniform structure, free from blemish. From these
statues and ornamental figures of various forms were cut. The prevalent
color was a bright red or pink. Certain varieties showed a beautiful
veining of red and white, sometimes in the form of ripple marks, in other
cases of fragments that have been recemented. These were probably
from the Jurassic, and perhaps would not be found most durable for work
exposed to the weather.
The sandstone from the Dakota Formation is usually of a gray or red-
dish cast, and, with little care, would probably rival the famous Berea
stone of northern Ohio. Quite extensive quarries have been opened,
such as the Evans' quarry near Hot Springs, and near Rapid City. Its
use has thus far been mainly local, but should there be a demand created
inexhaustible supplies are readily accessible. The samples of the stone
from the Black Hills, presented at the World's Fair, were tested by the
United States Ordnance Department at the Watertown Arsenal, in Massa-
chusetts. The test was made by covering the compressed surface with a
facing of plaster of Paris to secure an even bearing in the testing machine.
The blocks were in cubes of 4 inches each way. The principal results
are given in the following:
GEOILOGY OF SOUTH DAKOTA. 155
TABLE.
Crushing Pres-
f
ROCK AND LOCALITY. sure Per
Square Inch.
Sample I, from the Black Hills Quarry Company, pink color------- IO,532 pounds
Sample 2, * tº e tº tº º * * buff color------- 8,401 pounds
Sample 3, tº gº * e * * light drab color--| 5,937 pounds
Sample Mount Lookout Quarry--------------------------------- 4,516 pounds
Sample from Evans' Quarry------------------------------------| 6,305 pounds
Sample I, of Lem Creek Quarry Co.----------------------------- 5,582 pounds
Sample 2, tº e & & -----------------------------| 4,520 pounds
Sample 3, g g g tº wet, after 20 hours' immersion in 791 pounds
Water -----------------------------------------------------
Sample from Evans' Quarry (best)------------------------------- 7,491 pounds
A comparison of these figures with similar ones from corresponding
rocks elsewhere will be instructive. A sandstone from Hinkley, Minn.,
stood a pressure of 19,000 pounds per square inch, perpendicular to the
bedding and on edge 17,500. The Berea sandstone in Ohio, perpendie-
ular to the bedding, 10,000 pounds per square inch; on edge, 6,750.
The Niagara limestone of Stone City, Ia., stood, perpendicular to the
bedding, a pressure of 11,250, and on edge, 9,750. The Niagara lime-
stone of Lemont, Ill., stands a pressure, perpendicular to the bedding,
27,000 per square inch, and on edge, 26,250.
From this it will be seen that the samples from the Black Hills Quarry
Co. and from the Evan's Quarry Co. are nearly equal to the Berea stone
of Ohio.
IIMESTONE.
No limestone is found in the eastern part of the State except the so-
called chalkstone which has been quarried and used for building at
Mitchell, Scotland, Springfield and Brandon. When carefully selected
it stands weather well; some buildings show little imperfections after a
dozen years. The stone is very easily worked being so soft that it may
be cut with a knife. It is the same stone as that which is more exten-
sively used in Kansas, where it is known as the “magnesian limestone.”
Its composition is really argillaceous chalk. The difficulty of selecting
suitable blocks and the uncertainty of obtaining that which is durable
prevents its being used extensively. Moreover it is not widely exposed
except at a few points along the bluffs of the Missouri, between Yankton
and Chamberlain.
Sometimes quite large blocks of a hard compact magnesian limestone,
of a snow-white or light yellow color are found in the drift east of the
Missouri, but they are not abundant enough for extensive use.
156 GEOILOGY OF SOUTH DAKOTA.
In the Black Hills, extensive deposits of a gray limestone are found in
the Carboniferous. These have not been carefully examined, although
with little care almost any quality of limestone would probably be found
Some beds are quite silicious and therefore difficult to work. Dr. Car-
penter says: “The upper part of the Carboniferous limestone affords a
fairly good marble, nearly pure white.”
The purple limestone of the Triassic is of remarkable fine grain and
pure composition and is susceptible of fine polish, which may make it
valuable for ornamental work. It resembles the varigated marble from
Tennessee.
IPORPHY R.Y.
The igneous rocks found in the northern part of the Black Hills have
not yet been used for economic purposes but may eventually prove to be
valuable as building stone. Much difference will probably be found be-
tween the different varieties, namely: Trachyte, rhyolite and phonolite.
The green porphyry which is extensively exposed near Tilford seems likely
to prove a stone equal to granite in durability and more easily worked.
I am not aware whether attempts have been made to polish it but pre-
sume that it will be found susceptible of polish. The polish may not
stand exposure to weather, but for indoor work it may compare favorably
with marble. The strength of porphry, as has been tested in Minnesota,
is nearly equal to granite. A variety of trap rock from Taylor's Falls,
Chicago county, Minnesota, stood a pressure of 26,350 pounds. A sample
from near Duluth was of the same strength. It seems not improbable
that the samples from the Black Hills, although not tested, may prove
considerable stronger than the sandstone already tested from that region.
CEMENTS, CLAYS, SANDS, ETC.
GYPSU M.
The Red Beds of the Triassic have inexhaustible supplies of an excel-
lent quality of gypsum. Mills for the preparation of plaster of Paris and
stucco have been erected at Hot Springs and Sturgis. The report of the
Mineral Resources of the United States for 1893 gives the following
statement concerning South Dakota: “The product in 1891 of the crude
gypsum of the amount ground into land plaster, 1,560 short tons, valued
at $4,680. The amount of tons burned for plaster of Paris, 2,055, valued
at $4,938, total output for 1891, $9,618. For 1893 only 50 tons were
ground into plaster while 5,100 were burned into plaster of Paris, having
a value of $5,112. Total product, 7,014 tons, valued at $24,359.”
Dr. Carpenter gives the analysis of the gypsum as follows: “Lime,
34.60; sulphuric acid, 45.17; water, 20.15; silica, 0.03; total, 99.95, and
remarks that a purer quality is not found anywhere.
GEOILOGY OF SOUTH DAKOTA. 157
--- LIMIE.
In the eastern portion of the State limited quantities for local use have
been prepared by burning white limestone boulders in the drift. Small
quantities have also been made from the harder layers of the Niobrara
chalkstone. In the region of the Black Hills excellent lime has been
made from the purple limestone, for which purpose it is peculiarly fitted
by its unusual purity. It consists of 98.75 per cent of calcium carbonate.
Prof. Orton in his Economic Geology of Ohio recognizes two classes of
lime. One the magnesian or dolomitic, and the other the calcareous or
calcitie lime. The lime derived from the purple limestone belongs to
the latter class and would be classed as a hot, strong, rich quick-slacking
and quick-setting lime. It is purer than the best Ohio limes. Prof.
Carpenter remarks:
“I have not had an opportunity to study the Carboniferous or ‘big white,
limestone' from an economic point of view, and can state but little as to
its value. The upper part is shaly, the lower part silicious. About 200
feet, composing the central portion, is of a gray or whitish color and ap-
pears to be uniformly fine. It has been used somewhat as a flux and is
used for building purposes west of Hermosa and probably at other points.
The lime produced is pure white, without gray, and is probably magne-
sian.”
PORTT/ANI) CEMENT.
So far as has yet been discovered there is no hydraulic limetone in
our State, but deposits admirably fitted for the production of Portland
cement abound in several localities. The only point at which the indus-
try is developed is two or three miles west of Yankton on the bluffs of
the Missouri river. At that point extensive beds of chalkstone are easy
of access, and above them 15 or 20 feet of the dark plastic clays of the
Pierre formation. The cement is prepared by the grinding of the chalk-
stone and the clay and mixing them in the proper proportion, with the
assistance of water, then, after drying the mud and burning it, it is ground
into cement. This has been found to be of the most excellent quality; in
fact, the materials are so easily worked that any proportion of carbonate
of lime and silicate of alumina may be quite accurately obtained.
The manufacture of Portland cement seems to be growing in favor and
importance throughout the country. The output of our State for 1892 was
3,400 barrels, at a value of $68,000.00; in 1993, 33,739, at a value of
$69,502.00. This indicates an increase in the reputation of the cement. It
was used very successfully at the Worlds Fair, and is used very exten-
sively in various parts of the west for sidewalks and other outdoor work, as
well as for other uses to which it is commonly put. The Niobrara chalk-
stone and the overlying Pierre clay may doubtless be found in close rela-
tion to one another at many points along the banks of the Missouri from
Yankton to Chamberlain.
&
158 * GEOLOGY OF SOUTH IDAKOTA.
POTTER’s CLAY.
*
At Sioux City extensive deposits of potter's clay have been found in
the lower portion of Fort Benton, or the upper part of the Dakota. No
exposure has been found of this deposit upon the Dakota side and per-
haps it may not exist at the eastern end of the State. Yet, at the west-
ern and corresponding strata of the Dakota are extensively exposed
around the Black Hills, and doubtless afford favorable localities for man-
ufacture. It is likely also that at many points clays of the Fort Pierre
and the Fort Benton may be found well adapted for this purpose.
FIRE CLAY,
This exists in the lower layers of the Dakota formation around the
Black Hills. Tests made of the deposits of fire clay near Rapid City
showed it to be of fine quality. Two layers of it, several feet in thick-
ness, are extensively exposed on the south side of the gap at that place.
BRICK CILAYS.
The Loess commonly affords an excellent quality of brick clays; some-
times, however, it is so filled with limy concretions that it is greatly in-
jured for this purpose. This deposit, it will be remembered, abounds in
the extreme southeastern corner of the State. The silt capping of the
high terraces along the Missouri and other streams also frequently affords
loamy clay well adapted for this purpose.
At other localities where these supplies are wanting, the loamy portions
of the alluvial deposits on the flood plain of the large streams furnishes
suitable brick clay. Sometimes the clay may be made by the mixture of
the alluvial deposit, or fine sand, with the finer qualities of the Cretaceous
clays that are usually near at hand.
SAND AND GRAVEL.
Deposits of sand and gravel abound along the streams near the Black
Hills, not only in the channel but often times in larger deposits along
the tops of the high terraces. In the eastern portion of the State simi-
lar deposits are found along the upper streams and the old channels
that were occupied by streams during the glacial period. In the deposits
that have been opened, prominent gravel beds are found near Hudson
on the Big Sioux and near Sioux Falls. Most of the State where covered
with the Cretaceous clays may not furnish supplies of sand sufficient for
local needs, but upon the Tertiary and Lignitic areas little trouble will
be felt in this respect.
GEOLOGY OF SOUTH DAKOTA. 159
FUELS.
The obtaining of fuels is one of the most urgent demands of our State.
Most of our Territory is without trees and even hay is not sufficiently
abundant for burning, although it was used for that purpose in earlier
years.
In the Black Hills and in the immediate vicinity of the larger streams
wood is found in abundant quantities. f
COAL OR LIGNITE.
There are three horizons more or less exposed in our State in which
mineral fuel may be hopefully looked for. Namely: The Carboniferous,
the Dakota and the Laramie or Lignitic.
The first, though extensively exposed in the Black Hills, seems clearly
to have been deposited under circumstances decidedly unfavorable to the
formation of coal in that locality. We have on a previous page referred
to the probability of coal having been formed at this age in the region
between the Black Hills and the eastern part of the State and have also
called attention to the impossibility of its being obtained unless there
has been some disturbance of the strata which has not yet been discovered.
We have already alluded also to the occurrence of lignite in the upper
part of the Dakota formation about Centerville and the extreme south-
eastern corner of the State. Traces of similar deposits have been found
also as far east as Peterson, Iowa, on the Little Sioux river. In all cases
the abundance of water and absence of roof will probably render the
small deposits at that horizon entirely inaccessible at the eastern end of
State. Wherever this horizon is exposed about the Black Hills we may
look hopefully for beds of lignite, possibly of sufficient thickness and suf-
ficient excellence to reward the labor of mining it. The mines at New-
castle, over the line in Wyoming belong to this horizon and in Utah and
Colorado there are valuable mines found in a similar geological position.
It would seem from the marking of coal on Newton’s map at the north
end of the Hills that traces of this mineral were there found in this for-
mation.
We have already in our description of the Laramie formation called
attention to the fact that Prof. N. H. Winchell, while in connection with
the Ludlow expedition to the Black Hills in 1874, reports beds of lignite
5 to 6 and even 8 feet in thickness, in the Cave Hills in Ewing county.
There were also found beds of lignite 2 to 3 feet in thickness, as far east
as Reinhart county, between the Moreau and Grand rivers. The fact that
valuable beds occur not far away in North Dakota and west in Wyoming
call for a careful examination of this region to determine, if possible,
whether workable beds of similar value can be found within our own bor-
ders,
160 GEOLOGY OF SOUTH DAKOTA.
P.E.A.T. f
This is mentioned to call attention to the possibility of finding deposits
of this material upon the East and West Coteaus outside of the First
Moraine. It is not improbable that the recurrence of droughts and the
burning of prairies has prevented the formation of extensive deposits of
this kind or the destruction of them where they have been formed. Yet
it is conceivable that in the lakes and marshes in these localities which
have been long exposed to circumstances favorable to the formation of
peat and similarly situated to localities in Iowa and Minnesota, where §
peat is found, that valuable deposits may yet be found. The occurrence
of numerous glacial lakes and in many localities of perennial waters, with
a high altitude and cooler climate, are all favorable to this result.
gº WATERS.
The State of South Dakota extends from the belt of sufficient rains on
the east across the semi-arid and arid belts to the Black Hills on the
west, which are also supplied with sufficient rains. The clayey character
of the soil together with the lack of rainfall renders the central portion of
the State too arid for agricultural purposes especially upon the uplands.
JRAIN FALL.
. The average rainfall of the State, according to published reports of the
Signal Service is about 22 inches. On the east of a line passing a little
west of Milbank, Watertown, Alexandria and Scotland the average rain-
fall is 30 to 40 inches. West of that line to a line passing near Fort
Sisseton, Faulkton, Miller, Chamberlain and also in the Black Hills, the
average is 20 to 30 inches. Over the rest of the State it is from 15 to 20.
RIVERS.
We mention this but briefly here and would simply say that the main
streams are pre-ennial, yet fluctuating greatly in volume at different
seasons of the year.
Careful measurements have not been made of the amount of water car-
ried by these streams. Those which flow throughout their whole course are
the Missouri, Grand, Moreau, Cheyenne, Bad River, White, James and
Big Sioux. The other streams like the Maple, Elm, Turtle, Vermillion,
Beaver, which are found east of the Missouri in the drift region, have a
peculiar characteristic of expanding here and there into deep winding
basins while between they cease to flow in mid-summer, except through
the underlying gravel. Something of the same feature is also found in
the smaller streams west of the Missouri but not so remarkably developed.
It seems to be due to the inability of the streams to carry away the coarser
*
GEOLOGY OF SOUTH DAKOTA. 161.
;
*
material and hence it is accumlated in grável bars. Not infrequently in
the Black Hills and in the vicinity of broken country the streams may
flow for some distance at their heads though they are dried up in their .
lower courses. This is true of most of the smaller streams issuing from
the Black Hills and many of the tributaries of the White river from the
south.
SPRINGS.
In general we may say that springs are scarce in South Dakota. This
is due in part to the slight rain-fall and in part to the impervious clay
near the surface underlying most of the State. Also to the fact that
where porous strata are locally developed, as under the drift, the clay
overlying from its plastic character slips down and seals up their ex-
posures near streams. In the extreme southeastern corner of the State
sorings of great durability, but not very copious issue from underneath
the Loess where streams have cut through it to the underlying drift.
Several springs of this class are found in Union and Lincoln counties.
Where the surface is rather abrupt in the drift area, as about Wessington
Hills, and various points on the east and west Coteaus, gravel deposits in
the old valleys of former glacial drainage sometimes become subterranean
watercourses which bring water to the surface. Notable examples occur
along the east slope of the Wessington Hills, including the well known
Wessington Springs.
These old watercourses also bring water to the surface under quite dif-
ferent circumstances, in perhaps a score of cases along the moraines west
of the Missouri. It may be laid down as a rule, that wherever an “alkali.”
lake-bed occurs a fresh water spring may be found by its side, where the
old channel enters it. The explanation of this striking phenomenon
is simple. These alkali basins occur in the deepest portions or ends
of the old channels and the accumulation of alkali is mainly due to their
continued flow and the constant evaporation of their waters.
A few large springs are reported along the Missouri in the vicinity of
Yankton and Running Water, which are supposed, by Prof. G. E. Culver
(Report on Irrigation, U. S. Dept. Agriculture, 1893), to issue from the
deep artesian supply of the Dakota formation. In the broken country of
the Tertiary area south of White river, and also in perhaps less degree in
the area occupied by the Fox Hills and Laramie formations springs may
be found when drouths have not been too severe. About the Black Hills
springs are numerous, as is commonly the case in mountainous regions.
Some of the most copious springs that may be found anywhere escape
from underneath the purple limestone, near Tilford and Hot Springs, and
also from the gravel deposits in the valleys of the larger streams, Ex-
II
162 GEOLOGY OF SOUTH DAKOTA.
amples of the latter class are the Cleghorn springs on Rapid creek and
the large springs on Amphibious or Beaver creek, near Buffalo Gap.
Many others might be named.
I, A KIES.
In the drift region east of the Missouri, especially in the belts formed
by the moraines, numerous lakes, from the size of ponds to those of ten or
fifteen miles in length, abound after a number of rainy seasons. Contin-
ued drouths, which sometime occur in this region, dry up the smaller of
these lakes one after another.
A few of the most important, which are pleasure resorts on account of
their beauty and groves surrounding them, are as follows: On the East
Coteau—Lakes Buffalo, Waubay, Kampeska, Poinsett, Albert, Thomp-
son, Herman, and Madison. Upon the West Coteau there are none so
lasting, although in favorable seasons Crow lake, White lake and Red
lake are attractive points, while Lake Andes, at a considerable lower level
and yet 200 feet above the Missouri, is perhaps the most lasting of them
all. Upon the upland west of the Missouri, on the summits of the divide,
shallow lake-beds are found and the larger ones are rarely without water.
WELLS.
In the drift-covered areas water may be obtained near the surface in
the bottom of watercourses and lake basins of various sizes, such as
abound in glaciated areas. These are derived quite directly from the
rainfall, and are limited. This is particularly noticeable in the wells sunk
in basins, for the smaller the basin the sooner will the supply become ex-
hausted, which often occurs in dry seasons. Separating the waters near
the surface from those connected with the older formations below, lies a
blanket of boulder clay, which has been described in a previous chapter.
Underneath it there usually occurs a stratum of sand and gravel several
feet in thickness. This also contains water, especially in its lower por-
tions, for it lies in an uneven position. When it is struck in the bottom
of valleys the water not infrequently rises several feet, sometimes to the
surface, as near Artesian City, in Sanborn county. Sometimes this
stratum of sand is found intervening between the drift clay and the un-
derlying Cretaceous clays; in that case there is little hope of finding
water without going down perhaps several hundred feet to the Dakota
sandstone. Concerning the region west of the Missouri and about the
Black Hills no such general statement can be made. A fuller explana-
tion of our water supply in wells will be found in the Report of the State
Engineer of Irrigation for this year.
! GEOLOGY OF SOUTH DAKOTA. 163
2
ARTESIAN WELLS.
We will simply say here that the Dakota sandstone, which underlies
nearly the whole State, wherever struck, except in rim of Black Hills,
abounds in water. The pressure is sufficient to bring it to the surface in
most parts of the James Valley, and the valley of the Missouri and its
western tributaries. The most western point at which this has been dem-
onstrated is at Belle Fourche, in Butte county. Wells of this sort have
not been tried in the Valley of the Cheyenne and White Rivers, but
their success is not very doubtful. The higher lands of the East Coteau
and the highlands west of the James and Missouri are probably above
the “hydraulic gradient” of this water supply. By hydraulic gradient
we mean the sloping plane to which the pressure at different points
will raise the water. *
From a comparison of the pressures in the different wells we find that
they vary quite regularly as follows: At Jamestown it is 1,619 feet
above the sea and this pressure continues southward with little variation
to Huron. There it begins to decline quite rapidly to Mitchell where it
is about 1,310. South and east from that point it rises to Tyndall where
it is 1,505 and then declines to southeast being 1,325 at Yankton and
1,185 at Vermillion. West from this line, so far as has been fully tested
the hydraulic gradient rises quite rapidly. Taking the latitude of Huron,
we find that it increases at the rate of about 4.3 feet per mile, being 1,950
feet at Highmore, the highest yet found in the State. In the latitude of
Mitchell it increases westward at nearly the rate of 10 feet to the mile
showing a pressure of about 1,800 feet at Kimball. The Pierre and
Chamberlain wells probably do not penetrate to the stratum of the high-
est pressure. Upon the map will be found a line indicating the eastern
limit of the area in which the pressure from the Dakota sandstone will
bring water to the surface. From the north line of the State to the vic-
inity of Salem the area is limited by the East Coteau rising above the
hydraulic gradient. From a point near the northeastern come of Han-
son county into Hutchinson county the limit is caused by the absence or
slight development of the water-bearing stratum. In the southern part
of the State the limit is mainly due to the hydraulic gradient falling be-
low the general upland level of the country. The cause of this remark-
able slope has not been definitely determined, but it is probably due to
leakage along the exposures of the Dakota formation in the eastern part
of Nebraska and about the quartzite area in our State. *
Besides the artesian wells derived from the Dakota Formation there are
a few small areas supplied from the sands underneeth the Drift. These
occur about Artesian City in Hanson county, in the southern part of
164 GEOLOGY OF SOUTH DAKOTA.
Miner county and at two or three points in Turner and Clay counties.
Probably other areas will be discovered as the country becomes more
known.
The water appearing in artesian wells doubtless enters the Dakota sand-
stone on the foothills of the Rocky Mountains, the Black Hills and other
ranges in Montana. From a study of geological data, which are far from
complete, it had been estimated that 326,805,600,000 cubic feet enters an-
nually which may be utilized mainly in our State. If much of the Dakota
in Montana lies above 1,300 feet above the sea, as is not improbable, there
is an important stored supply available besides. A fuller discussion of the
probable adequacy of this artesian supply and other interesting points
connected with this subject will be found in the Report of the State En-
gineer of Irrigation, already referred to.
MINERAL WATERS.
The waters of both springs and wells are quite frequently charged with
various soluable salts. Common ingredients from the wells found in the
glacial drift are carbonates and sulphates of iron and lime magnesia and
soda. The source of these seems to be the clays of the upper Cretaceous.
In cases where the water from the sand stratum containing it, is at first
sweet and palatable, when it stands in contact with the boulder clay it be-
comes contaminated, more or less with these salts. Moreover in wells
which pass through the drift and penetrate the shales of the Pierre the
contamination is still more marked. Sometimes a saline taste is so prom-
inent as to make it particularly attractive to animals. The waters of the
deep artesian wells contain nearly the same ingredients. These are some-
times so prominent as to seriously interfere with its desirability for drink-
ing purposes, but as a rule the water is considered to be both palatable
and healthful. Some of the springs which we have mentioned on a pre-
vious page distinctly contain free hydrogen sulphid. The composition of
the water at Hot Springs resembles that of many artesian wells. As yet
none of these springs reported, are utilized for medicinal purposes, except
those in the vicinity of Hot Springs.
AILRALI.
This term of popular use includes the salts already mentioned as they
are found in areas where the moisture has evaporated and left them in
perceptible quantities. A white effloresence, called by this name, is
frequently found in low places after the water has dried away, so also in
basins at all localities in the State in which drainage has accumulated
them. As before stated, there are a few large basins, where the concen-
tration of these salts is so great that vegetation is entirely absent. When
} *
GEOLOGY OF SOUTH DAKOTA. 165
water is abundant the salt seems not to be deleterious to plants, but in
the dry part of the season the alkali in the soil quite frequently becomes
so concentrated as to kill the grass and other plants. This appears not.
only in the basins and along dry water courses, but in spots here and
there over much of the country east of the Missouri.
|
j
NATURAL. G. A.S.
Natural gas has been reported from several localities as developed by
boring wells. In a few cases, as near Blunt, in the northern part of
Hughes and Sully counties, it has been struck in very limited quantities
below the drift clay. It probably does not exist in paying quantities at
that level. In the boring of the deep artesian wells considerable quanti-
ties have been found escaping with the water. Careful investigation of
the facts has not yet been made. Cases of this sort have been reported
from Miller and Pierre.
MECHANICAL POWER.
Perhaps we transcend the ordinary limits of the geological treatise in
touching upon this subject. Yet we naturally place under this head not
only the capabilites of ordinary water power which exist in running
streams, but also the novel source which, perhaps, at first developed
them in our State, namely artesian power. &
MILL SITES.
We have already in our second chapter given the slope of our princi-
pal streams and a reference to these pages will show that the capabilities
for water power within our State are great. The streams around the
Black Hills descend very rapidly and the water may be conveniently
stored in dams at many points. The difficulties which are felt over per-
haps most of our State are the absence of suitable material for building
dams, and also the soft materials bounding the channels. One of the
finest opportunities for water power is the already noted one at Sioux
Falls, where the Big Sioux falls in rapids through a height of 75 to 80
feet over the red quartzite. Sites of smaller capacity are found upon the
Split Rock and other streams.
AIRTESIAN POWER.
Soon after the discovery of high pressure in artesian wells, invention
turned it to the running of machinery. This is done by the use of tur-
bine wheels. We are unable to state the full capacity of the wells, now
utilized in this way, but simply name as examples the pioneer Well Mill
of Yankton where the pressure of 48 to 56 pounds per square inch and a
ſlow of 1,600 to 2,000 gallons per minute runs a flouring mill of 40 bar-
166 GEOLOGY OF SOUTH" IDAKOTA.
rels capacity; the Hitchcock mill is run by a well flowing 1.240 gallons
per minute and have a pressure of 155 pounds per square inch, having a
capacity of 50 barrels per day. Besides running the mill it supplies
water to the town, maintains water in an artificial lake and irrigates a
farm. At Redfield, Springfield, Chamberlain and other points the
artesian wells are used for the running of electric lights, besides sup-
plying the common uses of waterworks. It will be easily seen that the
efficiency of a well for water power depends not only upon the pressure
of the water but volume of flow.
WIND POWER.
The average velocity of wind in South Dakota as shown by the Signal
Service at Huron for a series of nine years is found to be an average.
velocity of 10 miles per hour. A wind mill 10 feet in diameter with a
velocity of eight miles per hour will give litte more than a tenth of a
horse power per minute. One sixteen feet in diameter will give nearly,
half a horse power per minute. From this may be seen the capability of
wind for power.
SUN POWER.
The distinguished inventor Ericsson believed that his solar steam
engine would eventually prove to be his greatest invention. The sun’s
energy is enormous. Archimedes more than 2000 years ago used it suc-
cessfully in setting ships on fire at a distance, what may not be its cap-
abilities with modern improvements?
The chief difficulty with both wind and sun is their fickleness. With
an adaptation of cheap storage batteries may we not hope that this in
measure may be remedied.
Why may not the force of the wind and sun, through the medium of
electricity, some day be utilized for heating and lighting purposes, if not
for great power?
In France quick-lime has been successfully used for storing heat on a
small scale. May not this also be utilized in place of storage batteries
for supplementing these inconstant forces?
GEOLOGY AND SOILS.
The soils of our State have not yet been studied and little need be said
here except to make a few general remarks concerning them.
East of the line marking the margin of the drift on the map, the soil is
a dark rich loam with a clayey subsoil. The soil is generally deeper out-
side of the first moraine, and near streams, at the foot of slopes and in
basins inside it.
GEOLOGY OF SOUTH DAKOTA. 167
*
The Colorado, when not covered with the drift, forms what is called a
gumbo soil. Its qualities been already discussed. $
The Fox Hills, Laramie and Loup fork (Miocene) areas are usually
sandy, forming light, warm soils. ".
The Red Beds have a clayey character, which needs much moisture
and are apt to bake. M ..ºf
The Purple Limestone and Granite 3.I'ê8,S 3.I'ê particularly stony.
IN DE X,
A
Alkali, 91, 164. . .
Alluvial formations, 124.
Altitudes, 11.
Ammonites, 65.
Ancient lakes, see lakes.
Archean rocks, 25, 134.
correlation of, 31, 34.
distribution of, 27.
formations, 21, 28.
origin of 25, 32, 33.
Arenicolites, 41, 42.
Artesian wells, 163.
Aberdeen, 81.
Andover, 80.
Artesian, .
Chamberlain, 77.
Harold, 80.
Highmore, 79.
Huron, 78.
Ipswich, 81.
Iroquois, 78.
LaysOn, 76.
Miller, 78. §
Mitchell, 77,
Pierre, 79.
|Plankinton, 77.
Salem, 77.
Scotland, 75.
Tyndall, 76.
Yalnkton, 75.
Atlantosaurus, 65.
B
Bad Lands. 3, 8.
topography of, 10, 103.
fossils of, 3, 105.
Bailey, Prof. J. W., 90.
Bain, #. Foster, 113.
Benton, or Fort Benton, 85,
BelemnlteS, 65.
Black Hills, 8.
Survey Of, 4.
topographpy of, 8.
Boxwork,47, 49.
Boulder Clay, Till.
Brontotherium, 106.
Brachiopods, 42.
Building Stones, 151.
C
Cambrian. 21, 37.
Calvin, Prof. S 90.
Öarpenter, Prof. F. R. 5, 28, 30, 31, 43, 45. 56, 60,
131, 142.
Caswell, J. H. 28.
Caves, 47,48, 50.
Catlinite, 36.
Carboniferous rocks, 21, 42, 44, 135.
extent of, 51.
fossils of, 51.
porphyry in, 51.
subdivisionS, 44, 46.
and Potsdam, 39.
and Trias, 52,
Cement, 156.
Portland, 157.
Cenozoic EOn, 101. *º-
Chamberlin, Prof. T. C. 116, 117.
Chalkstone, 87,138.
origin of, 90.
Clark, Capt. 3.
Clays, 156.
brick. 158.
fire, 158.
otter’s, 158.
Coal, 159. See lignite.
Colorado formation, 85.
altitude of Surface, 88.
extent, 87.
Origin, 92.
Cope, Prof. E. D. 5, 82, 85, 103, 111,
Copper, 148.
Cotton, mineral, 50.
Cretaceous rocks, 55, 66, 137.
and Jurassic, 65.
Cycads, 71.
Crinoids, 64.
Crooks’ tower, 52.
Crosby, Prof W. A. 5, 43, 121, 130, 144.
Crystalline rocks, 20.
Cyathophylloid corals,
horns,
resemble petrified
D
Dakota, formation, 68.
character of, 69.
exposures, 68, 70.
lignite, 73.
origin of, 83, 84.
position, 81.
Definitions, 19.
I)evereaux, W. P. 144, 145.
Devonian rocks, 43, 135
Origin, 44.
Devil’s tower, 129.
Diabase, 20.
Dike, 20.
I)inosaur, (terrible lizard) 99.
DIOrlte, 20.
Dip, 19.
Drift, 112.
glacial, 112.
a qheolls, 120.
western and northCrm, 121. &
Stratified, 113.
*
*
{
%
•e GEOLOGY OF SOUTH DAKOTA. ,
E
Economic, Geology, 142.
Eldridge, G. H., 86.
Elevations, 11. &
Eocene, 101, 138.
Eon, 20. *
Colian depositS, 125.
ºquus beds, 112.
Eruptive rocks, 127.
Evans, Dr. John, 3. \
Explanations, 19.
Explorations, 3.
i
Fault, 20.
Rormations, 21.
|Port Benton group, 85.
characters, 89. I
and eruptive rocks, 131.
Fort Pierre group
agricultural ëffect, 90.
Characters, 88.
extent, 88.
Fossils, 19.
Carboniferous, 44, 46, 51.
Colorado, 86, 89.
Dakota, 71,73, 82.
Jurassie, 64, 65.
Laramie, 96.
Miocene, 3, 105.
Potsdam, 37, 40, 41.
Pleistocene, 125.
Trent On, 43.
Free, Pres. A. T., 43.
Fox Hills group, 93, 138.
extent, 94.
Characters, 95-
Fuels, 159. A.
Gi
GaS, 165.
Garnets, 29.
Glacial £eriod, See Quaternary, 128.
Glacial drift, 112.
Glacial striae, 112, 140.
Glauconite, greensand, 42.
Gneiss, gneissic, 20. 3
Gold, 142.
annual Output, 147.
kinds of deposits, 142.
Granite, 20,128, 151.
Origin, 26, 32.
age of, 32, 134.
Graphite, 150.
Greisen, 20.
Gypsum, 58, 156.
annual output, 156.
analysis, 156.
H
Hall, Prof. C. W., 36.
Hall, Prof. Ja.s., 3.
Hay, Prof. Robert, 106.
Hayden, Dr. F. v., ºº,” ".
Headden, Prof. W. P., 33, 56.
History of Explorations, 3.
Geological of Dakota, 183.
HomeStake lead, 143.
Hobbs, Prof., 36, 128.
Huronian, 26, 31.
Hyatt, Prof. A, 5.
I
Ice Age, see Quaternary,
benefits Of, 141.
W
i
Igneous rocks, 20, 127.
Iron ore, 29, 148.
Irving, #rof. R. D. 35.
J
Jansen, Prof. H. W. 56.
“Jasper,” see Quartzite.
Jenney, Prof.
Jura.SSic. 55, 60, 137.
and Cretaceous, 65.
fossils, 64. &
Jura-Trias, Jurassic and Triassic.
tº.
K
Keweenian or Keweenawan, 26. .
King, Clarence, 85, 86, 107, 109.
L
Lacustrine deposits, 124.
LaCCOlite, 20.
Lakes, 162.
Lake Arickare(?, 140.
Cheyenne, 109.
Dakota, 124, 141.
Sioux, 107. ... *
Laramie formation, 96, 98, 188.
extent, 96.
fossils, 97,138.
lignite, 97.
Origin, 99.
Laurentian, 26.
Lead, 146, 148.
Leads, 20.
Lewis, Capt. 3, 88.
Lignite, 73, 97, 136, 137, 138.
Lignitic, See Laramie.
Lime, 157.
Limestone, 43, 45, 56, 89.
LOeSS, 122
derived from Tertiary, 122.
Loup Fork beds, 108.
fossils, 109.
Origin, 109.
M
McBride, Prof. T. H. 71.
MamelonS, 132.
Mammoth, 126.
Manganese, 149.
Mal’ble, 31, 57.
Marcou, Prof. J. 90.
Marsh, Prof. O. C. 5, 65.
MaSSive, 20.
Maximillian, Prince, 3.
Meek, F. B. 3,60.
Mesozoic (middle life) formations, 55.
Metamorphism, 26.
Mica, 151.
Miocene rocks, 101, 102, 139.
and eruptive rocks, 131.
fossils, 105.
Sand dikes, 106.
Mineral Ores, 142.
Mineral cotton, 50.
Mineral Waters, 164.
MOntana formation, 86.
Moraines, 113, 140.
Origin 114.
first Outer Ol' Altamont, 115.
Second, Or Gary, 116.
third or Antelope, 117.
fourth, 117.
MOSaSaul, 87.
. P. 4, 28, 40, 68, 105, 120. ,
i
170
GEOILOGY OF SOUTH DAKOTA.
N
Neocene, 101. 4, 28, 30, 38, 41, 46, 52
3. *) y
Newton, Prof. Henry, 6i, ió5. €té.” ”
Nicollett, J. N. 3, 90.
Nickel, 149.
Niobrara formation, 85.
exposures, 87.
O
Oligocene, 101, 103.
Onyx cave, 50.
Oreodon, 106.
Oreodon beds, 102.
Osars, 118.
Owen, Dr. D. D. 3.
P
Paleozoic, (Ancient life) formations, 37.
Peat, 160.
Pebbles, elongated, 30, 33.
limestone, 31.
Phonolite, 20, 129.s.
Pierre, see F. T. Pierre, 85.
Pipestone, 36.
#; 101, 102, 110.
Pleistocene, 50, 112.
Porphyry, 20, 128, 156.
age of, 131.
and gold, 144.
in Carbonlferous, 51.
and Cretaceous, 131. .
POSt-Cretaceous or Laramie, 96.
Potsdam, 21, 37, 39, 134.
extent, 38. -
limestone pebbles in, 38.
and Carboniferous, 39.
Power Mechanical, 165.
artesian, 165.
Sun, 166.
wind 166.
water, 165. -
Pterosaur, (winged lizard), 87.
Purple limestone, 55, 56, 156, 157.
Origin Of, 57.
Pyrites, 147.
decomposing, 88.
Quartzite, 26, 29, 151.
teStS, 153
SIOux, 34.
“ extent of, 35. .
Quaternary depositS, 112, 140.
life of, 125.
R
Rainfall, 160.
Red Valley, 8, 55.. .
Red Beds, see Triassic.
RiverS, 16, 160.
River Vaſieys, 9.
terraces, 10, 122.
#. 20, 129.
Ruby Basin, 146.
Russell, I. C., 5.
Salt deposited, 57, 59.
Sand dikes, 106.
Sandstone, 153.
tests, 155.
Sanidin, 128.
St. John, O., 72.
Schists and slates, 20, 28, 29, 133.
Qrigin of, 30, 133.
Scolithus, 41, 42.
Scott, Prof. W. B., 5, 103.
Sedimentary rocks, 19. `
Selenite, 88.
Silurian rocks, 21, 42, 135.
Silver, 148.
Sioux lake, 107.
Sioux Falls,
Origin of, 140.
Soils, 90, 94, 165.
Springs, 161.
Imineral, 164.
Stanton, T. W., 87.
Stratum, strata, 19.
Stratified rocks, 19.
Striation of rocks, 112, 140.
T
Table of altitudes, 11.
artesian wells, 75, 80.
Carboniferous rocks, 44.
Cretaceous formations, 67.
Sandstone tests, 155.
Tertiary, 101.
TriaSS1C, 55.
geological formations, at end of Volume.
Table lands, 8.
Terry’s Peak, 38, 129.
Tertiary formations, 101.
extent of, 109.
Till, 113.
Tin, 149.
Titanotherium, 106.
Titanotherium beds, 102.
Topography of the State, 7.
Trachyte, 20, 129.
Trentón iméstone, 42.
fossils of, 43. &
Triassic formation, 55. 136.
cause of color 59.
Origin, 59.
U
Unconformity, where strata are not parallel.
Unconformity belween º
Carboniferous and Triassic, 58.
Cretaceous and Jurassic, 65.
Potsdam and Archean, 41.
SchistS and Slates, 28.
Upham, Warren, 35.
V
Van Hise, Prof. C. R., 30, 32, 34, 35.
“Volcanoes,” 88.
Volcanic action, 129, 132.
Volcanic dust, 132.
W
Ward, L. F., 62, 71.
Warren, G. K., 4.
Waters, 160.
mineral, 164.
Wells, 162.
artesian, 163.
artesian records, 75–80.
White, Dr. C. A., 72,82, 86, 99.
White River beds, 103.
Alkali absent, 107.
Conglomerate, 105.
Fossils, 105.
Sand dikes, 106.
Silica in, 104.
Origin of, 107.
Willis, Bailey, 97.
Winchell, Prof N. H., 4, 45, 52, 56, 84, 98, 131
Wind Cave, 48.
GEOILOGY OF SOUTH DAKOTA. 171
---
*****--~~~- ---, -e-...--------> <--------------~~~~-
ERRATA,
* Most of the typographical errors found in this volume are to be attrib-
luted to the imperative haste with which it has been printed. Wherever
these do not impair the validity of statement, we let them pass.
º On page 22, in the Table of Geological Formations, such confusion ap-
pears that the reader is referred to a revised form of the same at the end
of the volume, opposite the map.
- Sºn page 65 for “Atlantas aurus” read “Atlantosaurus.”
172 i GEOLOGY OF SOUTH DAKOTA.
*
< ; *::: & ~xº~ x
*…* :
_X^. \.
t
A TABLE OF SOUTH DAKOTA GEOLOGICAL FORMATIONs,
(ARRANGED STRATIGRAPHICALLY.)
# * ~
Eons. Systems. Groups and Stages. Deposits. Thickless.
ſ Quaternary, *
Pleistocene Feet,
* Terraces, Gravel, loam, etc., 5-ro'
O Loess, Buff loam, 5—IOO
3. Drift, Boulder clay gravel, etc., IO-I 50
N Tertiary, }
& 4 Pliocene,
Z. Equus Beds (?) Loam, sand and clay, 5–30
§ Miocene,
Loup Fork Beds, Sand, gravel and loam, 25-75
White River Beds, White clay, sandstone, grits, etc. 250–400
º Eocene, Absent. l
ſ Cretaceous,
Later, { ;
Laramie, Sandstone, shales and lignite, 1,000–2,000
º Fox Hills, Sandstone, shales and clays, IOO–I 50
O Colorado,
3. - Fort Pierre, Dark clays and shales, 350–700
N Niobrara, Chalkstone and shales, 50–2OO
S 3 Ft. Benton, Dark clay and shales, 50–2OO
% Dakota, Sandstones and clays, 2OO–5OO.
> Earlier, Absent.
Jurassic, Sandstones, marls and clays, 2OO-350
Triassic, Red clays and purple lime- 3OO–40O
U Stone. $
ſ Carboniferous, Limestones, sandstones and 570-785
shales.
C Devonian, Absent (?) O—25
S. Sºlurian,
Q - Upper, Absent (?)
ſº Lower,
: Trenton, Bluff limestone, etc., 25–50
nº | Cambrian,
Potsdam, Brown sandstone, etc., 250–300
U Acadian, Absent (?)
: ſ Keweenian, Absent.
% Huronian,
ſº Upper,
T. & Sioux Quartzite, Quartzite, etc., I,000–3,000
O Lower,
p. Black Hills Slates, Schists and granites, IO,OOO—IOO,OOO
* Laurentian, Absent (?)

SUPEPLEMENTARY NOTES ON THE MAP. i
The Drift or Boulder Clay govers all the surface east of the margin marked. It varies from 1
foot to perhaps 200 feet in thickness, and probably averages over 50.
The outlines of older formations as drawn on the map are less confidently given where, they are
covered by the Drift. The Sioux Quartzite and the Dakota, surrounding it, are probably drawn
too widely and too regularly, being covered more with the Golorado.
The “Eastern Limit of the Artesian Area” has reference to the main one, related to the Dakota
sandstone. There are several Small areas, with shallow wells, which derive their waters from
sands beneath the Boulder Clay.
31
Moos N
souri DAKOIA, by J. E. TODD. s.
0 Pse" Q R
Geologist soa.
T
9i N W
29
43°
-- ºf-
30
J. Dakota. º:
X -
aw dº.
an
º
“g-º-º-º-º:
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