ENCES 
 LIBRARY 
 
 IVERSITY OF CALIFORNIA. 
 
 FROM THE LIBRARY OF 
 
 DR. JOSEPH LECONTE. 
 GIFT OF MRS. LECONTE. 
 
 No. 
 
A 
 
 TEXT-BOOK 
 
 GEOLOGY 
 
 DESIGNED FOR SCHOOLS AND ACADEMIES. 
 
 BY 
 
 JAMES D. DANA., LL.D., 
 
 SILLIMAN PROFESSOR OF GEOLOGY AND NATURAL HISTORY Hi YALE COLLEGE ; AUTHOR OP 
 
 " A MANUAL OF GEOLOGY," " A SYSTEM OF MINERALOGY," OF -REPORTS 
 
 OF WILKES'S EXPLORING EXPEDITION ON GEOLOGY, ZOOPHYTES, 
 
 ILLUSTRATED BY 375 WOOD CUTS. 
 
 PHILADELPHIA : 
 PUBLISHED BY THEODORE BLISS & CO. 
 
 LONDON: TRUBNER & CO. 
 1865. 
 
EAR . H 
 
 SCIENCES 
 LIBRARY 
 
 Manual of Geology : treating of the Principles of the Science, with special 
 reference to American Geological History. By JAMES D DANA, M.A., LL.D. Illus- 
 trated by a Chart of the World, and over one thousand figures, mostly from Ameri- 
 can sources. 
 
 814 pages, 8vo. Muslin $500 
 
 " Half Turkey morocco g 00 
 
 Principles of Physics ; or, Natural Philosophy. Designed for the \ se 
 of Colleges and Schools. By BENJAMIN SILLIMAN, JR., M.A., M.D , Professor of 
 Chemistry in Yale College. With seven hundred and twenty-two illustrations. 
 710 pages, small 8vo 3.50 
 
 First Principles of Chemistry. For the use of Colleges and Schools. By 
 Prof. B. SILLIMAN, Jr. 
 554 pages, 12ino 2.00 
 
 Entered, according to Act of Congress, in the year 1863, by 
 THEODORE BLISS & CO. 
 
 in the Clerk's Office of the District Court of the United States for the Eastern 
 District of Pennsylvania. 
 
 ELECTROTYPE!) BY L. JOHNSON & CO. 
 PHILADELPHIA. 
 
PREFACE. 
 
 IN preparing this abridgment of my Manual of Geology, 
 the arrangement of the larger work has been retained. The 
 science is not made a dry account of rocks and their fossils, 
 but a history of the earth's continents, seas, strata, moun- 
 tains, climates, and living races; and this history is illus- 
 trated, as far as the case admits, by means of American facts, 
 without, however, overlooking those of other continents, and 
 especially of Great Britain and Europe. 
 
 "No glossary of scientific terms has been inserted, because 
 the volume is throughout a glossary, or a book of explana- 
 tions of such terms, and it is only necessary to refer to the 
 Index to find where the explanations are given. 
 
 The teacher of Geology, and the student who would 
 extend his inquiries beyond his study or recitation-room, is 
 referred to the " Manual" for fuller explanations of all points 
 that come under discussion in the " Text-book, including a 
 more complete survey of the rock-formations of America 
 and other parts of the world, with many sections and details 
 of local geology, a much more copious exhibition of the 
 ancient life of the several epochs and periods and of the 
 principles deduced from the succession of living species on 
 the globe, a more thorough elucidation of the departments 
 of Physiographic and Dynamical Geology, a chapter on 
 the Mosaic Cosmogony, a large number of additional wood- 
 cut illustrations, and references to authorities, with personal 
 acknowledgments, besides a general chart of the world. 
 
 NEW HAVEN, CT., December 1, 1863. 
 
 iii 
 
 101129 
 
TABLE OF CONTENTS. 
 
 PAG* 
 
 INTRODUCTION , 1 
 
 PAET L Physiographic Geology, 
 
 1. General Characteristics of the Earth's Features 5 
 
 2. System in the Earth's Features 8 
 
 PAET II. Lithological Geology, 
 
 1. CONSTITUTION OP ROCKS 14 
 
 1. General Observations on their Constituents 14 
 
 2. Kinds of Rocks 20 
 
 2. CONDITION, STRUCTURE, AND ARRANGEMENT OF ROCK-MASSES 27 
 
 Stratified Condition 31 
 
 1. Structure. 31 
 
 2. Positions of Strata 36 
 
 3. Order of Arrangement of Strata 43 
 
 REVIEW OF THE ANIMAL AND VEGETABLE KINGDOMS. 
 
 1. Animal Kingdom 48 
 
 2. Vegetable Kingdom 60 
 
 PAET III, Historical Geology, 
 
 General Observations 63 
 
 I. AZOIC TIME OR AGE 72 
 
 II. PALEOZOIC TIME 78 
 
 I. AGE OP MOLLUSKS, OR SILURIAN AGE 78 
 
 1. Primordial or Potsdam Period 79 
 
 2. Trenton and Hudson Periods 85 
 
 3. Upper Silurian Era 94 
 
 iv 
 
CONTENTS. V 
 
 II. PALEOZOIC TIME (continued). PAGE 
 
 II. AGE OP FISHES, on DEVONIAN AGE 104 
 
 III. AGE OF COAL PLANTS, OR CARBONIFEROUS AGE 116 
 
 GENERAL OBSERVATIONS ON THE PALEOZOIC 142 
 
 DISTURBANCES CLOSING PALEOZOIC TIME 154 
 
 III. MESOZOIC TIME 162 
 
 REPTILIAN AGE 163 
 
 1. Triassic and Jurassic Periods 164 
 
 2. Cretaceous Period 188 
 
 GENERAL OBSERVATIONS ON THE MESOZOIC ERA 198 
 
 DISTURBANCES AND CHANGES OF LEVEL CLOSING MESOZOIC TIME 202 
 
 IV. CENOZOIC TIME 205 
 
 MAMMALIAN AGE 205 
 
 1. Tertiary Period 206 
 
 2. Post-tertiary Period 219 
 
 1. Glacial Epoch 220 
 
 2. Champlain Epoch 224 
 
 3. Terrace Epoch 227 
 
 3. Life of the Post-tertiary 229 
 
 GENERAL OBSERVATIONS ON CENOZOIC TIME 234 
 
 V. ERA OF MIND AGE OF MAN 236 
 
 GENERAL OBSERVATIONS ON GEOLOGICAL HISTORY 243 
 
 - PART IV Dynamical Geology, 
 
 I. LIFE 262 
 
 1. Peat Formations 263 
 
 2. Beds of Microscopic Organisms 265 
 
 3. Coral Reefs 266 
 
 II. THE ATMOSPHERE 271 
 
 III. WATER .' 273 
 
 1. Fresh Waters 273 
 
 2. The Ocean 283 
 
 3. Freezing and Frozen Waters, Glaciers, Icebergs 290 
 
 4. Formation of Sedimentary Strata 296 
 
 IV. HEAT .'. 299 
 
 1. Heat of the Globe 299 
 
 2. Volcanoes and Non-volcanic Igneous Ejections 301 
 
 3. Metamorphism and Origin of Veins 312 
 
 4. Movements in the Earth's Crust.... 318 
 
VI CONTENTS. 
 
 IV. HEAT (continued). PAGE 
 
 Movements of the Earth's Crust. 
 
 1. Plications, Mountains..... 318 
 
 2. Joints Slaty Cleavage 323 
 
 3. Earthquakes 324 
 
 4. Origin of the Earth's General Features 326 
 
 Y. CONCLUSION 336 
 
 APPENDIX, 
 
 1. Catalogue of American Localities of Fossils 341 
 
 2. Mineralogical Implements, etc 344 
 
 INDEX.., .. 349 
 
INTRODUCTION. 
 
 1. Rock-structure of the earth's crust. Beneath the soil 
 and waters of the earth's surface there is everywhere a base- 
 ment of rocks. The rocky bluffs forming the sides of many 
 valleys, the ledges about the tops of hills and mountains, and 
 the cliffs along sea-shores, are portions of this basement 
 exposed to view. 
 
 The rocks generally lie in beds; and these beds vary from 
 a few feet to hundreds of yards in thickness. The different 
 kinds are spread out one over another, in many alternations. 
 Sometimes they are in horizontal layers; but very often 
 they are inclined, as if they had been pushed or thrown out 
 of their original position; and in some regions they are 
 crystallized. Moreover, they are not all found in any one 
 country. 
 
 By careful study of the rocks of different continents, it 
 has been ascertained that the series of beds, if all were in 
 one pile, would have a thickness of 15 or 18 miles. The 
 actual thickness in most regions is far less than this. 
 
 These 15 or 18 miles out of the 4000 miles between the 
 earth's surface and centre are all of the great sphere that 
 are within reach of observation. 
 
 The series of rocks alluded to overlie, beyond all question, 
 crystalline rocks that are not part of the series. There is 
 good reason for believing, also, that, not many scores of 
 miles below the surface, the whole interior of the globe is 
 in a melted state. These fiery depths are nowhere open to 
 examination; yet the rocks ejected in a melted state from 
 
 i 
 
2 INTRODUCTION. 
 
 volcanoes or from the earth's fissures are supposed to afford 
 indications of what they contain. 
 
 2. Facts taught by the arrangement and structure of the rocks. 
 The various rocks afford proof that they were all slowly or 
 gradually made, the lowest in the series, of course, first, 
 and so on upward to the last. The lowest, therefore, belong 
 to an early period of the world, and those above to later 
 periods, in succession. 
 
 Some of the beds indicate, by evidence that cannot be 
 doubted, that they were made over the bottom of a shallow 
 ocean, like the muddy and sandy deposits on soundings ; 
 or along the ocean's borders, like the accumulations of a 
 beach, or of a salt-marsh; others, that they were formed by 
 the action of the waters of lakes, or of rivers; and others 
 still, that they were gathered together by the drifting of the 
 winds, as sands are drifted and heaped up near various sea- 
 coasts. In many of the rocks there are marks on the layers 
 that were made by the rippling waves or the currents when 
 the material of the bed was loose sand or clay ; or there are 
 cracks though now filled that were opened by the drying 
 sun in an exposed mud-flat ; or impressions produced by the 
 drops of a fall of rain. 
 
 In some regions the beds, after being consolidated, have 
 been profoundly fractured, and the fissures thus opened were 
 often filled at once with rock, in a melted state, proceeding 
 from the depths below. Again, they have been uplifted or 
 pressed into great folds, and mountain-ranges have some- 
 times been made as a consequence of the upturning ; and, in 
 addition, they have often undergone crystallization over a 
 country thousands or even hundreds of thousands of square 
 miles in area. 
 
 The succession of rocks in the earth's crust is, hence, like 
 a series of historical volumes, and full of inscriptions. It is 
 the endeavor of Geology to examine and interpret these 
 inscriptions. They are sufficient, if faithfully studied and 
 
INTRODUCTION. 3 
 
 compared, to make known the general condition of the con-N 
 tinents and seas in the course of the world's progress, and / 
 also to tell of the epochs of disturbance or revolution, and J 
 of mountain-making. 
 
 \ 3. Facts taught by the fossil contents of rocks. Again, 
 most of the beds contain shells, corals, and other related 
 forms, called fossils, so named because dug out of the earth, 
 the word being from the Latin fossilis, meaning, that which 
 is dug up. These fossils are the remains of living animals 
 that once inhabited the earth. The shells and corals were 
 formed by animals, just as the shell of a clam is now formed 
 by the animal occupying it, or corals of existing seas by the 
 coral animals. The various species that have left their re- 
 mains in any bed must have been in existence when that 
 bed was in progress of formation : they were the living 
 species of the waters and land at the time. 
 
 The fossils that occur in one bed differ in species entirely, 
 or nearly so, from those of every other bed in the series. 
 In other words, each bed has its own peculiar species, those 
 of the bottom almost or wholly unlike those in the one next 
 above; and those of this bed as much unlike those of the 
 following; and so on. Since, therefore, each bed contains 
 evidence as to what animals and plants were living when it 
 was forming, the study of the fossils of the successive beds ^ 
 is the study of the succession of living species that have \ 
 existed in the earth's history. 
 
 4 Objects of Geology, and Subdivisions of the science. 
 The preceding explanations afford an idea of the objects of 
 the science of Geology. They are 
 
 (1.) To study out the system in the earth's features. 
 
 (2.) To ascertain the nature and arrangement of the rocks. 
 
 (3.) To make out the true history, or succession of events, 
 as to the formation of rocks, the production of the features 
 of the surface and the disturbances of rocks, and the progress 
 and all changes in the living species of the globe. 
 
4 INTRODUCTION. 
 
 (4.) To determine the causes of all that has happened in 
 the earth's history, that it may be understood hQw rocks 
 were made, fractured, uplifted, folded, and crystallized ; how 
 mountains were made, and valleys, and rivers; how con- 
 tinents and oceanic basins were made, and how altered in^ 
 size or outline from period to period ; why the climate of" 
 the globe changed from time to time ; and how the living 
 species of the globe were exterminated, or otherwise affected 
 by the physical changes in progress. 
 
 There are, hence, four principal branches of the science : 
 
 1. PHYSIOGRAPHIC GEOLOGY, treating of the earth's phy- 
 sical features; that is, of the system in the exterior features 
 of the earth. (This department properly includes, also, the 
 system of movements in the water and atmosphere, and the 
 system in the earth's climates, and in the other physical 
 agencies or conditions of the sphere.) 
 
 2. LiTHOLOGiCAL GEOLOGY, treating of the rocks of the 
 globe, their kinds, structure, and conditions or modes of 
 occurrence. The word lithological is from the Greek lithos, 
 stone, and logos, discourse. 
 
 3. HISTORICAL GEOLOGY, treating of the succession in 
 the rocks of the globe, and their teachings with regard to 
 the successive conditions of the earth, or to the changes in 
 its ocea*ns, continents, climates, and life. 
 
 4. DYNAMICAL GEOLOGY, treating of the caoiges, or the 
 methods, by which the rocks were made, and by which all 
 the earth's changes were brought about. The word 'dy- 
 namical is from the Greek dunamis, power or force. 
 
 These causes have acted through the sustaining power ^ 
 and guidance of the great Cause of causes, the Infinite \ 
 Creator, who made matter and all the kinds of life, and 
 who has ever directed and still directs in every passing 
 event. 
 
PART I. - 
 
 PHYSIOGRAPHIC GEOLOGY. 
 
 UNDER the department of Physiographic Geology only a 
 brief and partial review is here made of the general features 
 of the earth's surface. 
 
 THE EARTH'S FEATURES, 
 1. GENERAL CHARACTERISTICS. 
 
 1. Size and form. The earth has a circumference of about 
 25,000 miles. Its form is that of a sphere flattened at the 
 poles, the equatorial diameter (7926 miles) being about 13 
 miles greater than the polar. . 
 
 2. Oceanic basin and continental plateaus. Nearly three- 
 fourths (more accurately, eight-elevenths} of the whole surface 
 are depressed below the rest and occupied by salt water* 
 This sunken part of the crust is called the oceanic basin, and 
 the large areas of land between, the continents, or continental 
 plateaus. 
 
 3. Subdivisions and relative positions of the oceanic basin and 
 continental plateaus. Nearly three-fourths of the area of the 
 continental plateaus are situated in the northern hemisphere, 
 and more than three-fourths of the oceanic basin in the 
 southern hemisphere. The dry land may be said to be 
 clustered about the North pole, and to stretch southward 
 in two masses, an Oriental, including Europe, Asia, Africa, 
 and Australasia, and an Occidental, including North and 
 
 5 
 
6 PHYSIOGRAPHIC GEOLOGY. 
 
 South America. The ocean is gathered in a similar manner 
 about the South pole, and extends northward in two broad 
 areas separating the Occident and Orient, namely, the 
 Atlantic and Pacific Oceans, and also in a third, the Indian 
 Ocean, separating thQ^southern prolongations of the Orient, 
 namely, Africa and Australasia. 
 
 The Orient is made, by this means, to have two southern 
 prolongations, while the Occident, or America, has but one. 
 This double feature of the Orient accords with its great 
 breadth ; for it averages 6000 miles from east to west, which 
 is far more than twice the breadth of the Occident (2200 miles). 
 
 The inequality of the two continental masses has its 
 parallel in the inequality of the Pacific and Atlantic Oceans; 
 for the former (6000 miles broad) is more than double the 
 average breadth of the latter (2800 miles). Thus there is one 
 broad and one narrow continental mass, and one broad and one 
 narrow oceanic area. 
 
 The connection of Asia with Australia, through the inter- 
 vening islands, is very similar to that of North America with 
 South America. The southern continent, in each case, lies 
 almost wholly to the east of the meridians of the northern ; 
 and the islands between are nearly in corresponding posi- 
 tions, Florida in the Occident corresponding to Malacca 
 in the Orient, Cuba to Sumatra, Porto Bico to Java, and 
 the more eastern Antilles to Celebes and other adjoining- 
 islands. It is, therefore, plain that Australia bears the same 
 relation to Asia that South America does to North America. 
 It is also true that Africa is essentially in a similar position 
 with reference to Europe. 
 
 The northern portion of the Orient, or Europe and Asia 
 combined, makes one continental area ; and its general course 
 is east and west. The northern portion of the Occident, or 
 North America, is elongated from north to south. 
 
 4. Oceanic depression and continental elevations. The depth 
 of the oceanic basins below the water-level is probably in 
 
 

 THE EARTH'S FEATURES. 
 
 some parts 50,000 feet. The mean depth is much less. The 
 depth across from Newfoundland to Ireland, along what is 
 called the telegraphic plateau, is from 10,000 to 15,000 feet. 
 Farther south, the Atlantic Ocean is undoubtedly very 
 much deeper; but the soundings hitherto made are not 
 trustworthy as to the exact depth. The mean depth of the 
 north Pacific between Japan and San Francisco has been 
 determined by Professor Bache, from the passage of earth- 
 quake-waves in 1855, to be IS^OOC^feet. This is the narrower 
 part of the Pacific Ocean, and is probably much less deep 
 than that in the southern hemisphere. 
 
 highest point of the continents that has been mea- 
 Bured is 29,000 feet : it is the peak called Mount Everest, in 
 the Himalayas. But the mean height of the continental 
 plateaus is only aboutJLOOO feet. The mean height of the 
 several continents has been estimated as follows : Of 
 Europe, 670 feet; Asia, 1150 feet; North America, 748 feet; 
 South America, 1132 feet; all America, 932 feet; Europe 
 and Asia, 1000 feet; Africa, probably 1600 feet; and Aus- 
 tralia, perhaps 500. The material in the Pyrenees, if spread 
 equally over Europ.e, would raise the surface only 6 feet ; 
 and that of the Alps, only 22 feet. Although some moun- 
 tain-chains reach to a great elevation, their breadth above 
 a height of 1000 feet is small compared with that of the 
 continents below this height. 
 
 5. True outline of the oceanic depression. Along the oceanic 
 borders the sea is often, for a long distance out, quite shal- 
 low, because the continental lands continue on under water 
 with a nearly level surface; then comes a rather sudden 
 slope to the deep bed of the ocean. This is the case off the 
 eastern coast of the United States, south of New England. 
 Off New Jersey, the deep water begins along a line about 
 80 miles from the shore; off Virginia, this line is 50 to 60 
 miles at sea; and thus it gradually approaches the coast to 
 the southward. The slope of the bottom for the 80 miles 
 
 2 
 
PHYSIOGRAPHIC GEOLOGY. 
 
 off New Jersey is only 1 foot in 700 feet. The true bound- 
 ary between the continental plateau and the oceanic depres- 
 sion is the commencement of the abrupt slope. The British 
 Islands are situated on a submerged portion of the European 
 continent, and are essentially a part of that continent, the 
 limit of the oceanic basin being far outside of Ireland, and 
 extending south into the Bay of Biscay. New Guinea is in 
 a similar way proved to be a part of Australia. 
 
 6. Surfaces of the continents. The surface of a continent 
 comprises (1) low lands, (2) high or elevated plateaus or table- 
 lands, and (3) mountain-ridges. The mountain-ridges may 
 rise either from the low lands or the plateaus. The plateaus 
 are great areas of the surface situated several hundred feet, 
 or a thousand feet or more, above the sea, or above the 
 general level of the low lands. They are often a part of 
 the great mountain-chains. Sometimes plateaus include a 
 region between mountain-ridges, and sometimes the mass 
 of the mountains themselves out of which the ridges rise. 
 For example, the regions of northern and southern New 
 York are plateaus (the former averaging 1500 feet in height, 
 the latter 2000 feet) situated within, or on the borders of, the 
 Appalachian chain. The eastern part of New Mexico is a 
 plateau about 4000 feet above the sea, called the Llano esta- 
 cado, and Mexico is situated in another plateau, from which 
 rise various ridges and peaks ; and both of these, besides 
 others, are situated in the region of the Eocky Mountain 
 chain, or the great western chain of North America. The 
 Desert of Gobi, between the Altai and the Kuen-Luen range, 
 is a desert plateau about 4000 feet high. Persia and Ar- 
 menia constitute another plateau. These examples are suffi- 
 cient to explain the use of the term. 
 
 2. SYSTEM IN THE EARTH'S FEATURES. 
 
 1. General form of the continents resulting from their reliefs. 
 The continents are constructed on a common model, as 
 
THE EARTH'S FEATURES. 
 
 9 
 
 follows : they have high borders and a low centre , and are, there- 
 fore, basin-shaped. Thus, North America has the Appala- 
 chians on the eastern border, the Rocky chain on the west, 
 and between these the low Mississippi basin. Fig. 1 illus- 
 
 Fig. 1. 
 
 trates this form of the continent. In the section, b repre- 
 sents the Rocky Mountain chain on the west, with its double 
 line of ridges at summit; a, the Washington chain (including 
 the Sierra Nevada and Cascade range) near the Pacific 
 coast; c, the Mississippi basin; d, the Appalachian chain on 
 the east. ' 
 
 South America, in a similar manner, has the Andes on 
 the west, the Brazilian Mountains on the east, and other 
 heights along the north, with the low region of the Amazon 
 and La Plata making up the larger part of the great inte- 
 rior. Fig. 2 is a transverse section from west to east 
 
 Fig. 2. 
 
 
 (W, E), showing the Andes at a and the Brazilian Moun- 
 tains at b. In these sections the height as compared with 
 the breadth is necessarily much exaggerated. 
 
 In the Orient, there are mountains on the Pacific side, 
 others on the Atlantic ; and, again, the Himalayas on the 
 south face the Indian Ocean, and the Altai face the Arctic 
 or Northern Seas. Between the Himalayas (or rather tho 
 Kuen-Luen Mountains, which are just north) and the Altai 
 
 
10 PHYSIOGRAPHIC GEOLOGY. 
 
 lies the plateau of Gobi, which is low compared with the 
 enclosing mountains; and farther west there are the low 
 lands of the Caspian and Aral, the Caspian lying even below 
 the level of the ocean. The Urals divide the 6000 miles of 
 breadth into two parts, and so give Europe some title to its 
 designation as a separate continent. West of their meri- 
 dian there are again extensive low lands over middle and 
 southern European Eussia. 
 
 In Africa, there are mountains on the eastern border, and 
 on the western border south of the coast of Guinea ; there 
 are also the Atlas Mountains along the Mediterranean, and 
 the Kong Mountains along the Guinea coast ; and the inte- 
 rior is relatively low, although mostly 1000 to 2000 feet in 
 elevation. 
 
 In Australia, also, there are high lands on the eastern 
 and western borders, and the interior is low. 
 
 All the continents are, therefore, constructed on the basin- 
 model. 
 
 2. Relation between the heights of the borders and the extent 
 of the adjoining ocean. There is a second great truth with 
 regard to the continental reliefs; namely, that the highest 
 border faces the largest ocean. 
 
 By largest ocean is meant not merely greatest in surface, 
 but greatest in capacity, the depth being important in the 
 consideration. The Pacific, both in depth and surface, greatly 
 exceeds the Atlantic; so the South Pacific exceeds the 
 North Pacific and the South Atlantic exceeds the North At- 
 lantic. The Indian Ocean is also one of the large oceans; 
 for it extends eighty degrees of latitude south of Asia before 
 reaching any body of Antarctic land; and this is equivalent 
 to 5500 miles, nearly the mean breadth of the Pacific : more- 
 over, as it is much more free from islands than the Pacific, 
 it is probably the deeper of the two, and, consequently, yields 
 in capacity to no other ocean on the globe. 
 
 Each of the continents sustains the truth announced. 
 
THE EARTH'S FEATURES. 11 
 
 North America has its great mountains, the Rocky chain, 
 on the side of the great ocean, the Pacific ; and its small 
 mountains, the Appalachian, on the side of the small ocean. 
 So, South America has its highest border on the west; and 
 the Andes as much exceed in elevation and abruptness the 
 Kocky chain as the South Pacific exceeds in capacity the 
 North Pacific. The Orient has high ranges of mountains 
 on the east, or the Pacific side, and lower, as those of Norway 
 and other parts of Europe, on the west; and the Himalayas, 
 the highest of the globe, face the great Indian Ocean (besides 
 being most elevated eastward towards the great Pacific), 
 while the smaller Altai face the small Northern Ocean. In 
 Africa the eastern mountains, or those on the Indian Ocean 
 side, are higher than those on the Atlantic. In Australia 
 the highest border is on the Pacific side; for the South 
 Pacific, taking into view its range in front of east Austra- 
 lia, is greater than the Indian Ocean fronting west Aus- 
 tralia. 
 
 Hence the basin-shape, before illustrated, is that of a 
 basin with one border much higher than the other, and the 
 highest border the one that adjoins the largest ocean. 
 
 These features have a vast influence in adapting the con- 
 tinents for man. 
 
 America stands with its highest border in the far west, 
 and with all its great plains and great rivers inclined 
 towards the Atlantic ; for through the Gulf of Mexico the 
 whole interior, as well as, the eastern border, has its natural 
 outlet eastward. Had the high mountains of the continent 
 been placed on its eastern side, they would have condensed 
 the moisture of the winds before they had traversed the 
 land, and sent it back, in hurrying and almost useless tor- 
 rents, to the ocean ; but, being on the western, all the slopes 
 from the Atlantic to the tops of the Rocky Mountains lie 
 
 2* 
 
12 PHYSIOGRAPHIC GEOLOGY. 
 
 open to the moist winds, and fields and rivers show the 
 good they thus receive. 
 
 Again, the Orient, instead of rising into Himalayas on the 
 Atlantic border, has its great heights in the remote east, 
 and its vast plains and the larger part of its great rivers, 
 even those of central Asia, have their natural outlet west- 
 ward, or towards the same Atlantic Ocean. Thus, as Pro- 
 fessor Guyot has said, the vast regions of the world which 
 are best fitted by climate and productions for man are com- 
 bined into one great arena for the progress of civilization. 
 Both the Orient and the Occident pour their streams and 
 bear a large part of their commerce into a common ocean ; 
 and this ocean, the Atlantic, is but a narrow ferriage between 
 them, and vastly better for the union of nations than con- 
 nection by as much dry land : 3000 miles of dry land would 
 be, even in the present age, a serious obstacle to intercourse; 
 while 3000 miles of ocean draw the east and west only into 
 closer political, commercial, and social relations. 
 
PART II. 
 
 LITHOLOGICAL GEOLOGY. 
 
 THE term rock, in geology, is applied to all natural forma- 
 tions of rock-material, whether solid or otherwise. Not 
 only are sandstones and slates called rocks, but also 
 the loose earth, sand, and gravel of the surface, provided 
 they have been laid out in beds by natural causes. All 
 sandstones were once beds of loose sand ; arid there is every 
 shade of gradation from the hardest sandstone to the softest 
 sand-bed : so that it is impossible to draw a line between 
 the consolidated and unconsolidated. Geology does not 
 attempt to draw the line, but classes all together as rocks, 
 regarding consolidation as an accident that might or might 
 not happen in the case of the earth's beds or deposits. 
 
 Rocks may be studied simply as rocks, that is, with 
 reference to their composition, and collections may be made 
 containing specimens of their various kinds. Again, they 
 may be studied as rock-masses spread out over the earth 
 and forming the earth's crust ; and, with this in view, the 
 condition, structure, and arrangement of the great rock- 
 masses (called sometimes terrains} would come up for con- 
 sideration. The two subjects under Lithological Geology 
 are, therefore : (1.) The constitution of rocks ; (2.) The condi- 
 tion, structure, and arrangement of rock-masses. 
 
 13 
 
LITHOLOGICAL GEOLOGY. 
 
 1. CONSTITUTION OF ROCKS. * H 
 
 1. GENERAL OBSERVATIONS ON THEIR CONSTITUENTS. 
 
 Rocks consist essentially of mineral material. The fol- 
 lowing are the most common kinds. 
 
 1. Quartz, or Silica. Quartz, or, as it is called in chemistry, 
 silica, far exceeds^ all other species in abundance. It is one 
 of the hardest of minerals; it does not melt before the blow- 
 pipe, and does not dissolve in water. Its hardness and 
 durability especially fit it for this place of first import- 
 ance in the material of the earth's foundations. 
 
 It often occurs in crystals of the forms represented in 
 figs. 3, 4, though generally occurring in grains, pebbles, 
 
 Fig. 3. 
 
 Fig. 4. 
 
 or masses. It is distinguished ordina- 
 rily by its glassy aspect, whitish or 
 grayish color, "and an absence of all 
 tendency to break with a ({smooth sur- 
 face of fracturd (a quality of crystals 
 called cleavage). Although usually nearly 
 colorless or white, it is very often red- 
 dish, yellowish, brownish (especially smoky brown), and 
 even black; and the lustre is sometimes very dull, as in 
 chalcedony, flint, and jasper. The sands and pebbles of tho 
 sea-shores and gravel-beds are mostly quartz, because 
 quartz resists the wearing action of waters better than any 
 other common mineral. For the same reason, most sand- 
 stones and conglomerates consist mainly of quartz. 
 
 The hardness (on account of which it scratches glass 
 easily), infusibility, insolubility, non-action of acids, and 
 absence of cleavage, are the characters that serve to distin- 
 guish quartz from the other ingredients of rocks. 
 
 Although quartz is one of the original minerals of the 
 earth's crust, the quartz of rocks is not all directly of mine* 
 ral origin. Part of it perhaps a large part has passed 
 through living beings, either plants or animals; for some 
 
CONSTITUENTS OF ROCKS. 15 
 
 of the lowest species of these kingdoms of life have the 
 power of making siliceous shells or forming siliceous par- 
 ticles or spicules in their texture; and beds have been made 
 of these microscopic siliceous shells. The animal specieB 
 that secrete spicules of silica are the Sponges; and those 
 making siliceous shells are the microscopic forms called 
 Polycystines* The plants making siliceous shells are the 
 microscopic kinds called Diatoms. (See page 61.) 
 
 2. Silicate> Silica also occurs in many of the other rock- 
 making minerals, constituting what are called silicates. It 
 exists, thus, in combination with J,he bases alumina, mag- 
 nesia, lime-, potash, soda, the oxyds of iron, and a few 
 others. 
 
 Pure alumina, the most important of the above-mentioned 
 bases in the silicates, is hard, infusible, and insoluble, and 
 therefore adapted to be next in abundance to silica* When 
 crystallized, it is the hardest of all known substances, ex- 
 cepting the diamond, it being the gem sajytfiirfr) A massive 
 or rock-like variety, reduced to powder, is emery. 
 
 Magnesia, well known under the form of calcined mag- 
 nesia, is as hard as quartz when crystallized, and equally 
 infusible and insoluble. 
 
 Lime is common quick-lime. Potash and soda are the 
 alkalies ordinarily so called. These three ingredients are 
 found in those silicates that contain also either alumina or 
 magnesia, or both. The same is true, for the most part, of 
 the oxyds of iron. The compounds they form have a degree 
 of fusibility that docs not belong to the simple alumina- 
 silicates, and which fits them for being the constituents of 
 igneous or volcanic rocks. The following are the most 
 common of these silicates : cj j^ 
 
 (1.) Feldspar. Feldspar consists of silica and alumina 
 along with lime, potash, or soda. Common feldspar, or oxho- 
 clase, contains mainly potash, along with the silica and alu- 
 mina; albite contains, in place of the potash, soda; and 
 
16 LITHOLOGICAL GEOLOGY. 
 
 labradorite, another kind of feldspar, contains mainly lime. 
 The specific gravity is 2.4-2.7. 
 
 Either of these kinds of feldspar is distinguished from 
 quartz by having a distinct cleavage-structure, the grains 
 or masses breaking easily in two directions with a flat and 
 shining surface. They are nearly as hard as quartz, often 
 white, but sometimes flesh-red. The albite is usually white ; 
 and the labradorite often brownish, with generally a beau- 
 tiful play of colors. 
 
 (2.) Mica. Mica consists of silica and alumina, along with 
 potash, lime, magnesia, or oxyd of iron. It cleaves easily 
 into tough leaves, thinner than the thinnest paper and 
 somewhat elastic. On account of its transparency, when 
 colorless, it is often used in the doors of stoves. Its most 
 common colors are whitish, brownish, and black/' 
 
 The minerals quartz, feldspar, and mica are the con- 
 stituents of granite ; and they may be distinguished in it" 
 as follows : the quartz by its more glassy lustre and want > 
 of cleavage; the feldspar by its being more opaque than 
 quartz, and its having cleavage ; the mica by its very easy 
 cleavage into thin, elastic leaves. 
 
 (3.) Hornblende and pyroxene. Hornblende and pyroxene 
 consist, alike, of silica along with magnesia, lime, and prot- 
 oxyd. of iron. They are both of dark-green, greenish-black, 
 and bjaek colors in most of the rocks formed of, them, 
 though sometimes gray and white. Both are cleavable. 
 Hornblende often occurs in slender needle-shaped crystals. 
 There are fibrous varieties of each, called asbestus. They are 
 nearly as hard as feldspar, but much heavier than it (spe- 
 cific gravity = 3-3.5), and in general much more fusible. 
 
 (4.) Garnet Tourmaline Andalusite. These are other 
 silicates, of very common occurrence in rocks. They are 
 usually found in crystals distributed through a rock. Gar- 
 net is commonly in dark red, brownish, or black crystals 
 of 12 or 24 sides (dodecahedrons or trapezohedrons). The 
 
CONSTITUENTS OF ROCKS. 
 
 17 
 
 first of these forms is represented in fig. 5, showing garnets 
 distributed through a mica schist. Tourmaline is generally 
 
 Fig. 5. 
 
 Fig. 6. 
 
 in oblong 3, 6, 9, or 12 sided crystals, shining and black; 
 also at times blue-black, brown, green, and red. The crys- 
 tals are common in gneiss and mica schist, and are at times 
 imbedded in quartz (fig. 6). Andalusite is found in imbedded 
 crystals in argillaceous schist : the form is nearly a square 
 prism. The interior of the 
 crystals is very frequently 
 black or grayish-black at the 
 centre and angles (fig. 7), while 
 the rest is nearly white; and 
 this variety is called made, or 
 chiastolite. 
 
 (5.) Talc and serpentine. 
 Talc and serpentine are com- 
 pounds of silica with magnesia 
 and water. They both have a greasy feel, especially the talc. 
 Talc is a very soft mineral. It is often in foliated plates or 
 masses like mica; but the folia, or leaves, though separating 
 rather easily and flexible, are not elastic. The usual color 
 is pale green. 
 
 A massive granular talc, of whitish, grayish, or greenish 
 color, is called soapstone, or steatite. Serpentine is harder 
 than talc. It occurs as a dark-green massive rock, of a very 
 
18 LITIIOLOG1CAL GEOLOGY. 
 
 fine-grained texture : it is rarely foliated, and when so, the 
 leaves are not easily separated and are brittle. It may be 
 carved with a knife, and it differs in this, and also in its being 
 lighter, from compact hornblendic rocks. 
 
 3. Carbon, Carbonic Acid, Carbonates. (1.) Carbon. Car- 
 bon is familiarly known under three names and conditions : 
 (1.) Diamond^ (2.) Charcoal; (3.) Graphite. The last is the 
 material of lead-pencils, and is called also black lead, though 
 containing no lead. The first is the hardest of all known 
 substances; the last, one of the softest. 
 
 In Geology, carbon is most important in the state of 
 mineral coal, which is carbon mixed with other ingredients, 
 especially some of a bituminous kind. The variety con- 
 taining bitumen or bituminous substances burns on this 
 account with a bright flame, and is called bituminous coal. 
 The harder kind, with little or no bitumen, burning with a 
 very feeble-bluish or yellowish flame, is anthracite. Lignite 
 is a coal retaining in part the structure of the original 
 wood, and having an empyreumatic odor w T hen burned. 
 
 (2.) Carbonic acid is a gas consisting of carbon and oxygen. 
 It composes about 4 parts by volume of 10,000 parts of 
 the atmosphere, is formed in all combustion of wood or coal, 
 and is given out in the respiration of animals. 
 
 (3.) Carbonate of lime, or calcite, the essential ingredient 
 of limestone and marble, consists of carbonic acid and lime. 
 It crystallizes in a great variety of forms, a few of which 
 are represented in figs. 8, 9. It cleaves easily in three direc- 
 tions with bright surfaces ; as may be seen on examining even 
 the grains of a fine white marble. It is rather soft, so as to 
 be easily scratched with a knife ; dissolves in diluted acids 
 (chlorohydric or sulphuric) with effervescence, that is, with 
 an escape of the gas carbonic acid ; and when heated (as in a 
 lime-kiln, or before the blowpipe) it burns to quick-lime with- 
 out melting. By its effervescence with acids it differs from 
 all the minerals before mentioned. 
 
CONSTITUENTS OF ROCKS. 
 
 Fi<r. 8. 
 
 (4.) Dolomite is a carbonate of lime and magnesia; that is, 
 it differs from calcite in containing magnesia in place of 
 part of the lime. It makes up the mass of a variety of 
 limestone called magnesian limestone, which closely resem- 
 bles common limestone, but may be distinguished by its 
 effervescing scarcely at all with acid unless heat be applied. 
 The trial may be made by dropping a particle, as large as 
 half a grain of wheat, into a test-glass one-quarter filled 
 with a mixture, half and half, of muriatic acid and water. 
 
 The larger part of the carbonate of lime of rocks has been 
 derived directly from shells, corals, and other animal re- 
 mains. Animals take the material of their shells and other 
 stony structures from the waters of the globe, or from the 
 food they eat, through their power of secretion, that is, 
 the same power by which man forms his bones. After 
 death, the shells, corals, or bones, which are of no further 
 use to the species, are turned over to the mineral kingdom 
 to be made into rocks. The immense extent and thickness 
 of the earth's limestone rocks, nearly all of which are proba- 
 bly of organic origin, give some idea of the amount of life 
 that has lived and died through past time. 
 
 Carbonate of lime and silica are the two stony ingre- 
 dients which have been contributed largely by living 
 species to the earth's rock-formations. Mineral coal is an- 
 
 3 
 
SB L1THOLOG1CAL GEOLOGY. 
 
 other material abundantly contributed by the kingdoms of 
 life, the great beds of the coal period being all made from 
 the leaves and other parts of plants. 
 
 Sand Clay. Sand and clay are not minerals : they are 
 mixtures of minute particles of different minerals, produced 
 by the wearing down of different rocks. A large part of 
 common clay is pulverized feldspar mixed with some quartz. 
 Other kinds, having a greasy feel in the fingers, consist of 
 a material derived from the decomposition of feldspar and 
 allied minerals, and are composed of alumina, silica, and 
 water, mixed more or less with quartz and other impurities. 
 
 2. KINDS OF EOCKS. 
 
 1. Fragmental and Crystalline rocks. The minerals of which 
 a rock consists may be either (1) in broken or worn grains 
 or pebbles, like those of sand or clay or a bed of pebbles; or 
 (2) they may be in crystalline grains, in which case they 
 were formed where they now are at the time of the crys- 
 tallization of the rock. Such crystalline grains are angular, 
 and almost always show surfaces of cleavage. 
 
 The rocks of the first kind, consisting of a mingling of 
 fragments of other rocks, are called fragmental rocks ; and 
 those of the latter kind, crystalline rocks. The sands of a sea- 
 shore or the mud of a sea-bottom may make a fragmental 
 rock no less than coarser deposits. 
 
 Fragmental rocks are often called, also, sedimentary rocks, 
 because formed in general from sediment, or the earth depo- 
 sited by waters, either those of the ocean, lakes, or rivers. 
 
 Intermediate between rocks that are obviously either frag- 
 mental or crystalline, there are others, of a flinty compactness, 
 which show no distinct grains, and are, therefore, not easily 
 referred to either division. In the case of such rocks, the 
 geologist, in order to determine the division to which they 
 belong, has to examine the rocks associated with them. If 
 these associated rocks are fragmental, then the compact beds 
 
KINDS OF BOCKS. 21 
 
 are probably so also; but if these are crystalline, then they 
 are probably related to the crystalline. Experience among 
 rocks is required to decide correctly in all such cases. 
 
 2. Metamorphic and Igneous rocks. The crystalline rocks 
 are either metamorphic, or igneous^ 
 
 1. Metamorphic rocks are those which have been altered 
 or metamorphosed by means of heat. The alteration, when 
 most complete, consists in a complete crystallization of the 
 rock ; and when less so, in a consolidation or baking of it, 
 with sometimes no distinct crystallization. 
 
 Earthy sandstones and clay-rocks have been thus meta- 
 morphosed into granite, gneiss, and mica schist, and ordinary 
 limestone into statuary marble. 
 
 2. Igneous rocks are those which have been ejected in a 
 melted state, as from volcanic vents, or from fissures opened 
 to some seat of fires below or within the earth's crust. 
 
 3. Calcareous rocks. Calcareous rocks are the limestones. 
 To a great extent they have been formed from pulverized 
 animal relics, such as shells and corals ; and in this case they 
 are properly fragmental or sedimentary beds, although so 
 finely compact that this might not be suspected from their 
 texture. 
 
 Some limestones have been made from the accumulation 
 and consolidation of very minute shells, called Rbizopods. 
 These shells being no larger than the finest grains of sand, 
 no powdering was necessary. The limestone rocks formed 
 of them are not fragmental in origin. 
 
 Other calcareous rocks have been deposited from waters 
 holding the material in solution, and are, therefore, of chemi- 
 cal origin. Of this kind is the travertine of Tivoli near 
 Borne in Italy, and similar beds in many regions of mineral 
 springs, besides the petrified moss and trees of some marshy 
 regions. 
 
 4. Massive, schistose, laminated, slaty, shaly rocks. Rocks 
 are termed massive, when there is no tendency to break into 
 
22 LITIIOLOGICAL GEOLOGY. 
 
 slabs or plates; schistose, when crystalline and having a tend- 
 ency to break into slabs or plates, arising from the arrange- 
 ment more or less perfectly in layers of the mineral ingre- 
 dients (especially mica or hornblende); laminated, when 
 breaking into slabs or flagging-stones, and not in conse- 
 quence of a crystalline structure; slaty, when dividing easily 
 into thin, even, hard slates, like roofing-slate; shaly, when 
 dividing easily into thin plates like a slate-rock, but the 
 plates irregular and fragile. 
 
 The term schist is applied to a schistose rock; flag, to 
 a laminated rock; slate, to a slaty rock; shale, to a shaly 
 rock. 
 
 The kinds of rocks may be described under the four heads : 
 (1) Fragmental rocks, not calcareous; (2) Metamorphic rocks, 
 not calcareous; (3) Calcareous rocks; (4) Igneous rocks. 
 
 1. Fragmental Bocks. 
 
 1. Sandstone. Composed of sand, coarse or fine. When 
 of pure quartz sand, the rock is a siliceous sandstone; and if 
 very hard and a little pebbly, a grit. When earthy or 
 clayey, it is an argillaceous sandstone, the term argillaceous 
 meaning clayey. Argillaceous sandstones are usually lami- 
 nated, and, when very hard, may make good flagging-stone. 
 
 2. Conglomerate. Containing rounded or angular pebbles. 
 If rounded pebbles, the rock is often called a pudding-stone ; 
 and if angular fragments, a breccia; if the pebbles are of 
 quartz, a siliceous conglomerate; if of limestone, a calcareous 
 conglomerate. 
 
 3. Shale. Composed of clay or clayey earth, and having 
 a shaly structure. The colors are of all dull shades from 
 gray to black. When the shaly structure is very imperfect 
 and the rock is quite fragile, it is a marlite. [It is often 
 called, though not correctly ; a marl: a true marl is a clay 
 containing carbonate of lime derived generally from pow- 
 dered or broken shells.] 
 
KINDS OF ROCKS. 23 
 
 4. Tufa. A kind of volcanic sandstone, composed of vol- 
 canic sand or pulverized volcanic rocks : color, usually 
 brownish, brownish-yellow, grayish, and reddish. 
 
 2. Metamorphic Rocks. 
 
 1. Granite. A crystalline rock, consisting of quartz, feld- 
 spar, and mica. Color, usually light or dark gray or flesh- 
 red, the latter shade derived from a flesh-colored feldspar. 
 
 2. Gneiss. Closely like granite in composition, but some- 
 what schistose, and, consequently, having a banded appear- 
 ance on a surface of fracture transverse to the structure, 
 arising from the arrangement of the mica. If the color of 
 the gneiss is dark gray, it is banded usually with black 
 lines. Along the micaceous planes it breaks rather easily 
 into slabs, which are sometimes used for flagging. 
 
 3. Mica Schist. Related to gneiss, but consisting mainly 
 of mica, with more or less of feldspar and quartz, and, in 
 consequence of the mica, breaking into thin slabs. The 
 slabs have a glistening surface. In regions of mica schist 
 the dust of the roads is often full of shining particles of mica. 
 
 4. Syenite Hornblcndic Gneiss Horriblendic Schist. Syen- 
 ite resembles granite, but contains hornblende in place of 
 mica : the hornblende may be distinguished from mica by 
 its less perfect cleavage, and by the brittleness of the 
 lamina) afforded with some difficulty by the cleavage. A 
 rock like gneiss, but containing hornblende in place of mica, 
 is called hornblendic gneiss. A black or greenish-black 
 schistose rock consisting almost wholly of hornblende is 
 called hornblendic schist. 
 
 5. Talcose Schist. A slaty rock containing some talc, and 
 having, therefore, a greasy feel. Color usually grayish- 
 green, greenish, or brownish. 
 
 6. Chlorite Schist. A slaty rock containing an olive- 
 green mineral called chlorite, which is related to talc in 
 
 3* 
 
24 LITHOLOOICAL GEOLOGY. 
 
 being magnesian, but contains oxyd of iron, and is hardly 
 greasy in feel Color, dark green, and often olive green. 
 
 7. Slate, Argillite, Argillaceous Schist. These are different 
 names of roofing-slate and the allied slaty rocks. The tex- 
 ture is hardly at all crystalline, but the slates in the most 
 perfect kinds are hard, smooth in surface, and not absorbent 
 of water. Color blue-black, purplish, greenish, and of 
 other shades. 
 
 There is a gradual passage of the above rocks from gra- 
 nite into gneiss; from gneiss into mica schist; and from 
 mica schist and talcose schist into argillaceous schist. 
 
 8. Quartz Rock Quartzite. There is also a gradual pass- 
 age, through the more or less complete absence of the feld- 
 spar, into a micaceous quartz rock having a schistose struc- 
 ture ; and, by a more or less complete absence of the mica 
 into a pure massive quartz rock, called also quartzite. 
 Quartzite is only a very firmly consolidated sandstone made 
 of quartz sand. The consolidation has been produced by 
 the aid of heat, just as crystallization into gneiss has been 
 produced. For the former the sandstones were purely sili- 
 ceous, or nearly so, and for the latter, earthy sandstones. 
 
 9. Itacolumite. A peculiar laminated quartz rock occurs 
 in many gold-regions, which bends without breaking, 
 when in large thin plates. It contains scales of mica or 
 talc, and owes to this its laminated structure, toughness, 
 and flexibility. 
 
 3, Calcareous Rocks. 
 
 a. Uncrystalline. 
 
 1. Common Limestone. A compact rock, of grayish and 
 other dull shades of color to black, breaking with little or 
 no lustre, and with either a slightly rough or a smooth sur- 
 face of fracture. Consists essentially of carbonate of lime, 
 though often very impure from the presence of clay or earth. 
 When containing fossils, it is called fossiliferous limestone. 
 
KINDS OF ROCKS. 25 
 
 When consisting of carbonate of lime and magnesia, it is a 
 magnesian or dolomitic limestone, or dolomite, a kind not dis- 
 tinguishable by the eye from ordinary limestone. For the 
 distinctive characters, see page 17. 
 
 Many varieties of common limestone are polished and 
 used as marbles. The black marbles, and some of the yellow 
 and gray, are of this kind. Frequently they contain fossils. 
 
 2. Oolite. A limestone consisting of concretions as small 
 as the roe offish, whence the name, from the Greek don, egg. 
 Oolites or oolitic limestones occur in all the geological 
 formations, and are forming in modern seas about some 
 coral reefs. 
 
 3. Travertine. See page 21. Stalactites are limestone con- 
 cretions, of the form of icicles, hanging from the roofs of 
 caverns ; and Stalagmite is the same material covering their 
 floors. The waters trickling through limestone rocks hold 
 some carbonate of lime in solution (in the state of bicar- 
 bonate) ; and its deposition, as the dropping water evapor- 
 ates, produces these concretions and incrustations. 
 
 b. Crystalline. 
 
 Granular Limestone Statuary Marble. Limestone having 
 a crystalline granular texture, and, consequently, glistening 
 on a surface of fracture. The pure white kind, looking 
 when broken much like loaf-sugar, is, when of firm texture, 
 the marble used for statuary; and both this and coarser 
 varieties are employed for marble buildings. Most of the 
 clouded marbles are here included. 
 
 4. Igneous Rocks, 
 
 1. Granite-Wee Hocks. Granite is usually regarded as a 
 true igneous rock. But igneous rocks contain ordinarily 
 little or no silica in the condition of quartz. There are 
 several kinds of whitish and grayish crystalline igneous 
 rocks consisting of feldspar and hornblende, or feldspar and 
 
26 LITHOLOGICAL GEOLOGY. 
 
 pyroxene, or feldspar alone, each containing little or no 
 quartz. Mica is sometimes present in rocks of this kind. 
 
 2. Diorite. Consists of a, feldspar (albite) and hornblende; 
 and, though it may be light-colored from the abundance of 
 the feldspar, it is usually dark green and greenish-black, 
 from the preponderance of the hornblende. 
 
 3. Dolerite. Consists of a feldspar (labradorite) and 
 pyroxene, and has greenish-black, brownish-black, and 
 black colors. It is also often called trap. It may be either 
 crystalline granular, or of a flinty compactness. It fre- 
 quently contains also grains of magnetic iron ore. 
 
 4. Basalt. Like dolerite, but containing grains of a green 
 siliceous mineral, of a bottle-glass green color, called chryso- 
 lite or olivine. 
 
 5. Trap. Basalt, dolerite, and the diorites, especially the 
 dark-colored kinds, are often called trap, or trappean rocks. 
 
 6. Porphyry. Consists of feldspar (orthoclase) in a com- 
 pact condition, and contains crystals of feldspar of a paler 
 color and often whitish ; so that a polished surface is covered 
 with angular spots. Common colors, green and red. 
 
 Granite, dolerite, basalt, and other rocks are said to be 
 porphyritic when the feldspar is in distinct crystals. 
 
 A large part of the so-called porphyry is of metamorphic 
 origin, and not a true igneous rock. It sometimes consists 
 in part of hornblende or quartz. 
 
 7. Trachyte. Consists of feldspar, and has a rough surface 
 of fracture. Usually contains small air-cells, and also dis- 
 seminated crystals of a glassy feldspar. 
 
 8. Lava. Any rock that has flowed in streams from a 
 volcano, especially if it contains cavities, or, in other words, is 
 more or less scoriaceous. It is usually a dolerite, basalt, or 
 trachyte in composition. 
 
 9. Scoria is a light lava, full of cavities, like a sponge; and 
 pumice, a white or grayish feldspathic scoria, having the air- 
 cells long and slender, so that it looks as if it were fibrous. 
 
STRATIFIED ROCKS. 27 
 
 2. CONDITION, STRUCTURE, AND ARRANGEMENT OF ROCK- 
 MASSES. 
 
 The rocks which have been described are the common 
 material of which the great rock-masses of the globe consist. 
 These rock-masses occur under three conditions : (1) the 
 stratified; (2) the unstratified ; (3) the vein-form. 
 
 1. The Stratified condition. Stratified rocks are those 
 which lie in beds or strata. The word stratum (the singular 
 of strata) is from the Latin, and signified that which is 
 spread out. The earth's rocky strata are spread out in beds 
 of vast extent, many of them covering thousands of square 
 miles. The stratified rocks exposed to view over the earth's 
 surface far exceed in area the'unstratified. 
 
 They are the rocks of nearly the whole of the United 
 States and of nearly all of North America, and not less of 
 the other continents. Throughout central and western New 
 York and the States south and w^est, the rocks, wherever ex- 
 posed, are seen to be made up of a series of beds. And if the 
 beds are less distinct over a large part of New England, it 
 is, in general, only because they have been obscured by the 
 upturning and crystallization which the rocks have under- 
 gone since they were formed. 
 
 Fig. 10. 
 
 The preceding figure represents a section of the rocks 
 along the river below Niagara Falls. It gives some idea of 
 the alternations which occur in the strata. In a total height 
 of 250 feet (165 feet at the Falls, at F, on the right) there 
 
28 LITHOLOGICAL GEOLOGY. 
 
 are on the left 6 different strata in view and parts of 2 
 others, the upper and lower, making 8 in all. 1 is gray 
 argillaceous sandstone ; 2, gray and red argillaceous sand- 
 stone and shale; 3, flagstone, or hard laminated sandstone; 
 4, reddish shale or marlite and shaly sandstone; 5, shale; 6, 
 limestone; 7, shale; 8, limestone. Only two of these strata, 
 7 and 8, are in sight at the falls (at F). The alternations 
 are thus numerous and various in all regions of stratified 
 rocks. 
 
 It must not be inferred that the earth is covered by a 
 regular series of coats, the same in all countries ; for this is 
 far from the truth. Many strata occur in New York that 
 are not found in Ohio and the States west ; and each stratum 
 varies greatly in different regions, sometimes being lime- 
 stone in one and sandstone in another. 
 
 A stratum is a bed of rock including all of any one kind 
 that lie together, as either Nos. 1, 2, 3, 4, 5, 6, 7, or 8 in the 
 preceding figure. 
 
 ^formation includes the several strata that were formed in 
 one age or period. A subdivision of a formation, including 
 two or more related strata, is often called a group. 
 
 A layer is one of the subdivisions of a stratum. A stratum 
 may consist of an indefinite number of layers. 
 
 2. TTnstratified condition. Unstratified rocks are those 
 which do not lie in beds or strata. Mountain-masses of 
 granite are often without any appearance of stratification. 
 The rock of the Palisades, on the Hudson, stands up with a 
 bold columnar front, and has no division into layers. There 
 are similar rocks about Lake Superior. Most lavas of vol- 
 canoes have flowed out in successive streams; and, conse- 
 quently, volcanic mountains are generally stratified. But in 
 some volcanic regions the rocks rise into lofty summits 
 without stratification. Although true granite bears no 
 marks of proper stratification, it very often passes insensibly 
 into gneiss, which is a stratified rock; and there is evi- 
 
29 
 
 dence in this fact that granite is, generally, a stratified rock 
 which has lost the appearance of stratification in consequence 
 of the crystallization it has undergone. 
 
 3. Vein-form condition. When rocks have been fractured, 
 and the fissures thus made have been filled with rock-mate- 
 rial of any kind, or with metallic ores, the fillings are called 
 veins. Veins are therefore large or small, deep or shallow, 
 single or like a complete network, according to the cha- 
 racter of the fractures in which they were formed. They 
 
 Fig. 11. 
 
 Fig. 12. 
 
 may be as thin as paper, or they may be many ya^-ds, or 
 even rods, in width. Figures 11 to 14 represent some of 
 them. In fig. 11 there are two veins, a and b; in fig. 12, 
 
 Fig. 13. 
 
 Fig. 14. 
 
 ^\i 
 
 a network of thin veins ; in fig. 13, two of irregular form, 
 kind not uncommon ; in fig. 14, two large veins, of still more 
 irregular character, crossing one another. 
 
30 
 
 LITHOLOGICAL GEOLOGY. 
 
 65 4321 24 
 
 Many veins have a banded structure, like fig. 15. In 
 this vein, the layers 1, 3, 6, consisted of quartz; 2, 4, of 
 gneissoid granite; 5, of gneiss. Most 
 metallic veins are of this kind : the ores Fig. 15. 
 
 lie in one or more bands alternating 
 with other stony bands consisting of 
 different minerals or rock-material, us 
 calcite, quartz, fluor-spar, etc. 
 
 Those veins that have been filled with 
 melted rocks are usually called dikes: 
 they are not banded, and have regular 
 walls; and the rocks are igneous rocks. 
 They are often transversely columnar in 
 structure. Fig. 16 represents a dike, 
 and shows this transverse columnar structure. 
 
 4. Relation of stratified and true unstratified rocks and veins 
 in the earth's crust. The relations of the stratified and 
 unstratified rocks in the earth's crust will be 
 understood after considering the origin of the 
 crust. 
 
 The crust is believed to be the cooled exterior 
 of a melted globe. After the first crusting over 
 of the surface of the sphere, the ocean com- 
 menced to make stratified rocks over the exte- 
 rior, while the continued cooling, going on very 
 slowly, made unstratified rocks below. The ocean thus 
 worked over and covered up with strata nearly all, if not 
 all, the original unstratified crystalline rocks. Hence, 
 true unstratified rocks that is, those which were unstra- 
 tified in their first formation are of very small extent 
 over the globe. Even ordinary granite, as mentioned on 
 page 29, is not generally of this kind. Veins are a result of 
 fractures of the crust; and they too are of very limited 
 distribution. 
 
 Geology, consequently, has for its study, almost solely 
 
 a. 16. 
 
STRUCTURE OF ROCKS. 
 
 31 
 
 stratified rocks. Nearly all the facts in geological history 
 are derived from rocks of this kind. It is, therefore, import- 
 ant that the various details with regard to their structure 
 and arrangement should be well understood by the student. 
 
 STRATIFIED CONDITION. 
 
 1. Structure. 
 
 1. Massive, laminated^ and shaly structures. The massive, 
 laminated, and shaly structures of layers have been ex- 
 plained on p. 21. The massive is represented in fig. 17 a; 
 I 
 
 Fig. 17. 
 
 the laminated, in fig. 17 b ; and the shaly, in fig. 17 c. Sand- 
 stone is more or less laminated, according to the proportion 
 of clay or earthy material it contains. The same is true of 
 limestone. 
 
 2. Beach-structure. The beach-structure is illustrated in 
 fig. 17 d. The layer, instead of being composed of evenly- 
 laid material, consists of many irregular small layers, beds 
 of sand and others of pebbles, of small extent, being variously 
 mingled. This kind of layer is formed along sea-beaches, 
 being well shown wherever a sea-beach is cut through, so 
 that the interior is open to view. 
 
 3. Ebb-and-flow structure. The ebb-and-flow structure is 
 
32 
 
 LITHOLOGICAL GEOLOGY. 
 
 illustrated in fig. 17 e. A layer presenting it consists of 
 irregular subordinate layers, like those of beach origin ; but 
 these subordinate layers are of wider extent, and part of 
 them are obliquely laminated (see figure,) while other alter- 
 nate layers are laminated horizontally. Such a structure is 
 formed where currents intermit at intervals or are reversed, 
 as in the ebb and flow of the tides where they are connected 
 with heavy tidal waVfcs. 
 
 4. Wind-drift structure. A layer characterized by the 
 wind-drift structure consists of layers dipping in various 
 directions, sometimes curving and sometimes straight. (Fig. 
 17 /.) The hills of sand formed by the winds on a sea-coast 
 usually have this structure. The sands drifted over the 
 rising heaps form layers conforming to the outer surface, 
 and so may slope at all angles. In storms they may be 
 blown away in part, and afterwards be completed again ; 
 but then the layers, conforming to a new outer surface, 
 would have a different direction. In this way, by successive 
 
 Fig. 18. 
 
 Fig. 19. 
 
 destructions and re-completions, a bed of sand may be made 
 which shall consist of parts sloping in one direction and 
 
STRUCTURE OF ROCKS. 
 
 33 
 
 other parts in directions very different, with numerous 
 abrupt transitions, as illustrated in the drawing. 
 
 5. Ripple-marks. A gentle flow of water or its vibration, 
 over mud or sand, ripples the surface. Sandstone and clayey 
 rocks are often covered with such ripple-marks. (Fig. 18.) 
 
 6. Rill-marks. When the waters of a spreading or return- 
 ing wave on a beach pass by shells or stones lodged in the 
 sand, the rills furrow out little channels. Fig. 19 shows 
 such rill-marks alongside of shells in a Silurian sandstone. 
 
 7. Mud-cracks. When a mud-flat is exposed to the air or 
 sun to- dry, it becomes cracked to a few inches or so in 
 depth. Fig. 20 represents mud-cracks in an argillaceous 
 sandstone. The cracks were subsequently filled with stony 
 material, which was harder even than the rock itself; so 
 that the filling stands prominent above the general surface, 
 and is actually a network of veins. 
 
 Fig. 20. 
 
 Fig. 21. 
 
 8. Rain-prints. The impressions of rain-drops on sand or 
 a half-dry mud have often been preserved in the rocks, 
 appearing as in fig. 21. 
 
 9. Concretionary structure. Layers often contain spheres 
 
34 
 
 LITHOLOG1CAL GEOLOGY. 
 
 Fig. 22. 
 
 or disks of rock, which are called concretions. They result 
 from a tendency in matter to concrete or solidify around 
 centres. Some are no larger than grains of 
 sand or the roe of fish, as in oolitic limestone 
 (p. 25). Others are as large as peas or bullets, 
 and others a foot or more in diameter. Fig. 
 22 is one of a spherical form. Fig. 23 repre- 
 sents a rock made up of rounded concretions. 
 It shows also that they have sometimes 
 (though not always) a concentric structure. In fig. 24 the 
 concretions are flattened. 
 
 Fig. 24. 
 
 Fig. 25. 
 
 Concretions are usually globular in sandstones, lenticular 
 in laminated sandstones, and flattened disks in argillaceous 
 rocks or shales. All these kinds are shown in fig. 25. The 
 balls are sometimes hollow, and the disks mere rings. Fre- 
 quently the concretions have a shell or other organic object 
 
 Fig. 26. 
 
 Fig. 27. 
 
 Fig. 28. 
 
 at centre (fig. 26). They are often cracked through the 
 interior (fig. 27), the outside in such a case having solidified 
 while the inside was still moist, and the latter, afterwards 
 cracking as it dried : in such a case the cracks may become 
 
STRUCTURE OF ROCKS. 
 
 35 
 
 filled with other minerals, so that the concretion, on being 
 sawn in two and polished, may have great beauty. When 
 hollow, they may be afterwards incrusted within by crys- 
 tals (fig. 28) as of quartz, or by layers as of agate, and thus 
 make what is called a geode ; or they may become wholly 
 filled. Sometimes they contain a loose ball within, a con- 
 cretion within a concretion. 
 
 Basaltic columns (fig. 29), as they are often called, are col- 
 umns of igneous rock made by 
 the contraction of the mass when 
 cooling from fusion. The size 
 of the columns depends on a 
 concretionary structure forming 
 at the time within. The tops 
 of the columns are often con- 
 cave, or they become so as the 
 rock decomposes. 
 
 10. Jointed structure. The 
 
 rocks of a region are often divided very regularly by nume- 
 rous straight planes of fracture, all parallel to one another, and 
 cutting through to great depths. Such planes of fracture may 
 characterize the rocks for hundreds of miles. They are 
 
 Fig. 30. 
 
 catted joints; and a rock thus divided is said to present a jointed 
 structure. In many cases there are two systems of joints in 
 the same region, crossing one another, so that they divide 
 
 4* 
 
LITHOLOGICAL GEOLOGY. 
 
 the rock into angular blocks, or give to a bluff a front like 
 that of a fortification or a broken wall, as shown in fig. 30, 
 a view from the shores of Cayuga Lake. The directions 
 of such joints are facts which the geologist notes down with 
 care. 
 
 11. Slaty cleavage. The term slaty has been explained on 
 page 22. But one important fact regarding the structure is 
 not there stated, which is, that the slates are always trans- 
 verse to the bedding, that is, they cross the layers of stratifi- 
 cation more or less obliquely, instead of conforming to the 
 layers like the shaly structure. Slaty cleavage is in this 
 respect like the jointed structure; but it differs in having 
 the planes of fracture or divisional planes so close and nume- 
 rous that the rock divides into slates instead of blocks. 
 
 Slaty cleavage is confined to fine-grained argillaceous 
 
 Fig. 31. 
 
 rocks. If a rock is a coarse argillaceous rock or an argil- 
 laceous sandstone, it may have a jointed structure, but will 
 not have the true slaty cleavage. In fig. 31 the lines of 
 bedding or stratification are shown at a, &, c, d, while the 
 transverse lines correspond to the direction of the slates. 
 The same is shown in fig. 32, with the addition of a slight 
 irregularity in the slates along the junction of two layers. 
 
 2. Positions of Strata. 
 
 1. Original position of strata. Horizontal position. Ordi- 
 nary stratified rocks were once beds of sand or earth, or of 
 other kinds of rock-material, spread out for the most part 
 by the currents and waves of the ocean, but partly by the 
 waters of lakes or rivers. 
 
POSITIONS OF STRATA. 37 
 
 When the larger portion of the beds over the North Ame- 
 rican continent were formed, the continent lay to a great 
 extent beneath the ocean, as the bottom of a great, though 
 shallow, continental sea. The principal mountain-chains 
 the Bocky Mountains and the Appalachians had not yet 
 been made, and the surface of the submerged land was 
 nearly flat. The fact that the beds were really marine is 
 proved by their containing, in most cases, sea-shells or 
 corals, the relics of marine life ; and the great extent of the 
 continental seas is indicated by the beds covering areas of 
 tens of thousands of square miles, some of them extending 
 from the Atlantic border westward beyond the Mississippi. 
 In such great seas, having the bottom nearly flat, the de- 
 posits made by means of the currents and waves would be 
 nearly or quite horizontal. As they increased, they would 
 near the surface ; and here the action of the waves would 
 level off the upper surface of the beds, whether accumula- 
 tions of sand or earth, or of shells or corals. And if the 
 bottom were very slowly sinking, the accumulations would 
 still go on thickening, and the beds continue to have the 
 same level or horizontal position. 
 
 Many strata have been formed along the borders of the 
 continents; and here, also, they take horizontal positions. 
 The bottom of the border of the Atlantic, south of Long 
 Island, is, for 80 miles from the coast-line, so nearly 
 horizontal that, in a distance outward of 600 to 700 feet, it 
 deepens on an average only 1 foot; and if the area were 
 above the ocean, no eye would detect that it was not per- 
 fectly level. It is obvious that deposits over such a con- 
 tinental border, as well as those of beaches, would be very 
 nearly horizontal. 
 
 The deltas about the mouths of great rivers, like that of 
 the Mississippi, cover sometimes thousands of square miles. 
 They are made of the sands and earth brought down by the 
 river and spread out by the currents of the river and ocean. 
 
38 
 
 LITHOLOGICAL GEOLOGY. 
 
 They are, therefore, examples of the deposition of rock- 
 material on a scale of great extent ; and various strata have 
 been formed as deltas are formed. The beds of delta-deposits 
 are always horizontal or nearly so. 
 
 Other beds were originally vast marshes, like the marshes 
 of the present day, only larger. Such was the condition of 
 those beds in the coal-formation that contain coal. Now, 
 marshes have a horizontal surface; and marsh deposits, as 
 they accumulate, have a horizontal structure. Many coal- 
 beds contain stumps of trees (fig. 33) 
 rising out of the coal ; and they always 
 stand vertically on the bed, however 
 much it may be displaced, showing 
 that the bed was horizontal when 
 formed, or when the trees were grow- 
 ing. 
 
 Exceptions to a horizontal position. When a river empties 
 into a lake or sea, the bottom of which, near its mouth, 
 is very steeply inclined, the deposits of detritus made by the 
 river will for a while conform to the slope of the bottom, 
 
 Fig. 33. 
 
 as in fig. 34. When rivers fall down precipices, they make 
 a steep bank of earth at the foot, whose layers, if any are 
 observable, will take the slope of the bank. 
 
 But these and similar cases of exceptions to a horizontal 
 position are of small extent. 
 
 2. Dislocations of strata. Most of the strata of the globe 
 have lost their original horizontal' position, and are more 
 or less inclined ; some are even vertical or stand on end. 
 
 They are occasionally bent or folded as a quire of paper 
 
DISLOCATIONS OF STRATA. 39 
 
 might be folded, only the folds are miles, or scores Of miles, 
 in sweep. 
 
 They have often also been fractured, and the separated 
 parts have been pushed, or else have fallen, out of their 
 former connections, so that the portion of a stratum on one 
 side of the fracture may be raised inches, feet, or even 
 miles, above that on the other side. 
 
 It is stated on p. 1, that a thickness of rock equal to 15 
 or 18 miles is open to the geological explorer. This could 
 not be true, were all strata in their original horizontal posi- 
 tion ; for the most that would in that case be within reach 
 would not exceed the height of the highest mountain. But 
 the upturning which the earth's crust has undergone has 
 brought the edges of strata to the surface, and there is hence 
 no such limit : however deep stratified beds may extend, 
 there is no reason why the whole should not be brought up 
 so as to be exposed to view in some parts of the earth's 
 surface. 
 
 The following are explanations of the terms used in 
 describing the positions of strata : 
 
 1. Outcrop. The portions or ledges of strata projecting 
 out of the ground, or in view at the surface (fig. 35). 
 
 2. Dip. The angle of slope of inclined or tilted strata. 
 In figures 35, 36, dp is*the direction of the dip. Both the 
 angle of slope and the direction are noted by the geologist : 
 
 Fig. 35. 
 
 thus, it may be said of beds, the dip is 50 to the south, or 
 45 to the northwest, etc. 
 
40 
 
 LITHOLOGICAL GEOLOGY. 
 
 When only the edges of layers are exposed to view., it is 
 not safe to take the slope of the edges as the slope 'of the 
 layers ; for in figure 36 the edges on the faces 1, 2, 3, 4, are 
 
 Fig. 36. 
 
 all edges of the same beds, and only those of the face 1 
 would give the right dip. 
 
 The dip is measured by means of instruments called clino- 
 meters. In fig. 37, a b c d represents a square block of 
 
 Fig. 37. 
 d, 
 
 wood, having a graduated arc b c and a plummet hung 
 below a. Placed on the sloping surface A B, the position 
 of the plummet gives the angle of dip. This kind of 
 clinometer is often made in the form of a watch and com- 
 bined with a compass. In the same figure, e d f repre- 
 sents another clinometer. It has a level on the arm d e ; 
 and when the arm d f is placed on the sloping surface, 
 the other arm is raised until, as shown by this level, it 
 is horizontal ; the dip is the angle between the two arms, as 
 measured on the arc at the joint. To avoid errors from the 
 
DISLOCATIONS OF STRATA. 
 
 41 
 
 Fig. 
 
 unevenness of a rock, a board should be laid down first, and 
 the measurement be made on its surface. 
 
 3. Strike. The horizontal direction at right angles with 
 the dip, as s t in fig. 35. The direction of the line of outcrop 
 is often the true strike. 
 
 4. Fault. When strata have been fractured and the parts 
 are displaced, as in fig. 38, the 
 
 displacement is called a fault. 
 The coal-beds 1 and 2 in this 
 figure are thus faulted in two 
 places; and the amount of the 
 fault in either is the number of 
 feet or inches that one part is 
 above or below the other. 
 
 5. Folds or flexures. The rising or sinking of strata in 
 curving planes, as represented in the following sections, fig. 
 
 Fig. 39. 
 
 39, A, B ; and in the natural section, fig. 40, from the Ap- 
 palachian Mountains in Virginia. 
 
 Fig. 40. 
 
 In fig. 39, a x is the axis or axial plane of the fold. 
 
 6. Anticlinal. Having the strata sloping away from a 
 common line in opposite directions, as the layers either side 
 of a x in fig. 39, A : the axis is here called an anticlinal axis; 
 and a ridge made up of such strata is an anticlinal ridge. 
 The word anticlinal is from the Greek anti, in opposite direc- 
 tions, and klino, I incline. 
 
42 LITI10LOGICAL GEOLOGY. 
 
 7. Synclinal. Having the strata sloping towards a com- 
 mon line from opposite directions. In fig. 39, B, ax, ax are 
 anticlinal axes, and a' x', between the others, a synclinal axis; 
 or, viewing the former as anticlinal ridges, the latter is a 
 synclinal valley. The word synclinal is from the Greek sun, 
 together, and klino , I incline. 
 
 8. Monoclinal. Having the strata sloping in only one 
 direction. A valley made by the fracture of strata and the 
 slide of one side past the other, the dip of the two portions 
 remaining unaltered or but little so, is called a monoclinal 
 valley. The word monoclinal is from the Greek monos, one, 
 and klino. 
 
 9. Geoclinal. Having the general mass of the earth's 
 crust, but not the strata, sloping at surface towards a com- 
 mon axis of depression. Thus, a geoclinal valley is a depres- 
 sion of the surface produced by an uplift of the earth's crust 
 on either side of the depression, without a simple synclinal 
 dip in the strata bounding the depression, as the Connecti- 
 cut Valley, the Mississippi Valley. 
 
 10. Denudation Decapitated Folds. If the top of the fold 
 in fig. 41 were cut off at a b, there would remain the part 
 represented in fig. 42, in which 
 
 Fig. 41. Fig. 42. 
 
 there is no appearance of any 
 
 fold, and only a uniform series 
 
 of dips ; and although 1', 2', 3', 
 
 might appear to be the lower 
 
 strata of the series, they are 
 
 actually parts of 1, 2, 3. A long 
 
 series of such folds pressed together, and thus decapitated, 
 
 would make a series of uniform dips over a wide extent of 
 
 country. 
 
 The wear of the ridges of a country by water has often 
 produced the eifect here described over regions of folded 
 rocks. 
 
 In other cases, a similar wear has removed the rocks over 
 
UNCONFORMABLE STRATA. 
 
 43 
 
 great areas, or filled up intermediate depressions by soil : so 
 that the rocks are visible only at long intervals (as in fig. 
 
 Fig. 43. 
 
 43), and the faults which may exist are concealed from view. 
 Many of the difficulties connected with the study of rocks 
 arise from this cause. 
 
 11. Unconformable strata. When strata have been tilted 
 or folded, and, subsequently, horizontal beds have been laid 
 down over them, the two sets are said to be unconformable, 
 
 Fig. 44. 
 
 because they do not conform in dip. It is a case of uncon- 
 formability in the stratification. Thus, in fig. 44 the beds a b 
 are unconformable to those below them ; so also the tilted 
 beds c d are unconformable to those beneath, and the beds 
 ef to the beds c d. 
 
 It is plain that the folded rocks represented in figure 44 
 are the oldest, and that they were folded before a b or c d 
 were deposited. Again, it is evident that the beds c d are 
 older than the beds e /, and also that they were tilted and 
 faulted before the beds ef were formed. Thus the geologist 
 arrives at "the relative periods of occurrences in geological 
 time. If the precise age of the three sets of rocks here 
 represented could in any case be ascertained (as they gene- 
 rally may be), the periods of uplift would be more precisely 
 determined. 
 
 3. Order of Arrangement of Strata, 
 It has been explained that the strata are historical 
 
44 LITHOLOGICAL GEOLOGY. 
 
 records of past conditions of the earth's surface. In order, 
 therefore, that the records should make an intelligible his- 
 tory, all the parts should be arranged in their proper order, 
 that is, the order of time. The determination of this order is 
 one of the first things before the geologist in his exami- 
 nations of a country. 
 
 Many difficulties are encountered. 
 
 1. The strata of the same period or time called equivalent 
 strata, because equivalent in age differ, even on the same 
 continent. Sandstones and shales were often forming along 
 the Appalachians in Pennsylvania and Virginia, when lime- 
 stones were in progress over the Mississippi Valley. The 
 chalk formation in England contains thick strata of chalk; 
 but in North America the same formation exists without 
 any chalk. 
 
 2. When rocks have been forming in one region, there 
 have been none in progress in many others. Hence the series 
 of strata serving as records of geological events is nowhere 
 perfect. In one country one part will be very complete ; in 
 another, another part; and all have their long blanks, that 
 is, large parts of the series entirely wanting. In New York 
 and the States west to the Mississippi, there is only part of 
 the lower half of the series. In New Jersey there is part of 
 the lower half and part of the upper half, with wide breaks 
 between. Over a large part of northern New York there is 
 only the very earliest of rocks, those made before the first 
 fossiliferous beds were laid down. 
 
 The thickness of the fossiliferous series in the State of 
 New York, south of its centre, is about 13,000 feet; and north 
 of its centre they thin out to a few feet ; in Pennsylvania, 
 the maximum thickness is over 40,000 feet; in Indiana 
 and other adjoining States west and south, 3500 to 6000 
 feet. In Great Britain, the whole thickness above the 
 unfossiliferous' bottom-rocks is about 70,000 feet. The thick- 
 ness here given is the sum of the greatest thickness of each 
 
EQUIVALENCY OF ROCKS. 45 
 
 of the successive strata, and exceeds that existing at any one 
 point, as one formation may be thickest in one district, and 
 another in a district more or less remote. 
 
 3. The rocks of a country are to a great extent covered 
 with earth or soil, so that they can be examined only at 
 distant points. 
 
 4. The strata, in many regions, have been displaced, 
 folded, fractured, faulted, and even crystallized extensively, 
 adding greatly to the difficulties in the way of the geological 
 explorer. 
 
 The following are the methods to be used in determining 
 the true order of arrangement : 
 
 A. In sections of the rocks exposed to view in the sides 
 of valleys or ridges, the order should be directly studied, 
 and each stratum traced, as far as possible, through all the 
 exposed sections. 
 
 When, through large intervals, a covering of soil or water 
 prevents the tracing of the beds, other means must be used. 
 
 B. The aspect or composition of the rock may help to 
 determine which strata are identical. But this method 
 should be used with caution, for the reason stated above, in 
 1, that rocks made at the very same time may be widely 
 different ; and, conversely, those made in very different 
 periods may look precisely alike in color and texture. 
 
 C. Fossils afford the best means of determining identity. 
 This is so because of the fact, already mentioned, that the 
 fossils of an epoch are very similar in genera if not in 
 species the world over; and those of different epochs are 
 different. 
 
 As the kinds of fossils belonging to each period and age 
 are now pretty well known, and catalogues and figures have 
 been published, it is only necessary, on commencing the 
 investigation of a stratum, to collect its fossils, study them 
 with care, and then compare them with the figures and 
 descriptions to be found in works on the subject. In this 
 
46 LITHOLOGICAL GEOLOGY. 
 
 way it has been proved that the chalk formation exists in 
 North America, although there is no chalk to be found. In 
 the same manner the equivalents in America of the rocks of 
 Britain and Europe, Asia, or even Australia, are ascertained; 
 for this means of determination is a universal one, applying 
 to the equivalency of rocks in different hemispheres as well 
 as on the same continent. 
 
ANIMAL AND VEGETABLE KINGDOMS. 47 
 
 REVIEW OF THE AOTMAL AKD VEGETABLE 
 KINGDOMS. 
 
 THE following pages on the Animal and Vegetable King- 
 doms are inserted in this place to prepare the student 
 for the following portion of the work, on Historical Geology, 
 in which the progress of life is a prominent part. 
 
 Distinctions between an Animal and a Plant. 
 
 1. An Animal. An animal is a living being, sustained by 
 nutriment taken into an internal cavity or stomach, through 
 an opening called the mouth. It is capable of perceiving the 
 existence of other objects, through one or more senses. It 
 has (except in some of the lowest species) a head, which is 
 the seat of the power of voluntary motion, and which con- 
 tains the mouth. It is fundamentally a fore-and-aft struc- 
 ture, the head being the anterior extremity, and it is typi- 
 cally forward-moving. With its growth from the germ, 
 there is an increase in mechanical power until the adult size 
 is reached. In the processes of respiration and growth, it 
 gives out carbonic acid, and uses -oxygen. 
 
 A Plant. A plant is a living being sustained by nutriment 
 taken up externally by leaves and roots. It is incapable of 
 perception, having no senses. It has no head, no power of 
 voluntary motion, no mouth. It is fundamentally an up-and- 
 down structure, and, with few exceptions, fixed. In its growth 
 from the germ or seed, there is no increasing mechanical 
 power. In the process of growth, it gives out oxygen and 
 uses carbonic acid. 
 
 5* 
 
48 
 
 ANIMAL KINGDOM. 
 
 I. ANIMAL KINGDOM. 
 1. The Animal Structure. 
 
 The nature of an animal requires, for a full exhibition of 
 its powers, the following parts : 
 
 1. A stomach and its appendages to turn the food into 
 blood, with an arrangement for carrying off refuse material. 
 
 2. A system of vessels for carrying this blood throughout 
 the body, so as to promote growth and a renewal of the 
 structure. 
 
 3. A heart, or forcing-pump, to send the blood through the 
 vessels. 
 
 4. A means of respiration, or of taking air into the system 
 (as by lungs or gills), because this growth and renewal 
 require the oxygen of the air to act in conjunction with the 
 blood, as much as a fire requires air in order that the fuel 
 may burn. 
 
 5. Muscles, or contractile fibres, to act by contraction and 
 relaxation in putting the parts or members in motion. 
 
 6. A brain, or head-mass of nervous matter, and a system 
 of nerves, branching through the body, to serve as a seat 
 for the will and for the power of sensation and motion, and 
 to convey the determinations of the will and sensation 
 through the body. 
 
 In the lowest form of animal life, as some microscopic 
 Protozoans, the stomach is not a permanent cavity, but is 
 formed in the mass of the tissue whenever a particle of food 
 comes in contact with the body. In other words, a stomach 
 is extemporized as it is needed. In species of a little higher 
 grade, as Polyps, there is a mouth and stomach, with mus- 
 cles, an imperfect system of nerves when any, and a means 
 of respiration .through the general surface of the body; but 
 there is no distinct heart, and the animal is ordinarily fixed 
 to a support. 
 
ANIMAL KINGDOM. 49 
 
 2, Subdivisions of the Animal Kingdom. 
 
 There are/owr distinct plans of structure according to which 
 animals are made; and the species corresponding to each 
 make up what is called a sub-kingdom in the kingdom of ani- 
 mals. These four sub-kingdoms, or plans of structure, are 
 the following : 
 
 1. The VERTEBRATE : having (as in Man, Quadrupeds, 
 Birds, Eeptiles, and Fishes) an internal jointed skeleton, 
 of which the back-bone is called the vertebral column, and 
 each of its joints a vertebra. 
 
 The remaining sub-kingdoms have no internal jointed 
 skeleton. 
 
 2. The ARTICULATE : having (as in Insects, Spiders, Crabs, 
 Lobsters, Worms) the body and its appendages (as the legs, 
 etc.) articulated, that is, made up of a series of joints. 
 
 3. The MOLLUSCAN : havjng (as in the Oyster, Clam, Snail, 
 Cuttle-fish) a soft, fleshy body without articulations or joints ; 
 arid the appendages, when any exist, also without joints. 
 The name is from the Latin mollis, soft. 
 
 4. The EADIATE : having (as in the Polyp, Medusa, Sea- 
 urchin, Star-fish) the body, both externally and internally, 
 radiate in arrangement, the parts being arranged radiately 
 around the mouth and stomach, as in a flower or an orange 
 the parts are radiately arranged about its centre or central 
 axis. 
 
 Radiate animals take after the vegetable kingdom in type 
 of structure (plants also being radiates) ; yet they are strictly 
 animals, as they have a mouth, stomach, and other animal 
 organs. The type of structure in each of the other sub- 
 kingdoms is purely animal. 
 
 5. PROTOZOANS. Besides the above, ther-e are other species 
 of such extreme simplicity that neither of the systems of 
 structure above mentioned is apparent in them, and these 
 are, therefore, in a sense systemless animals. Many have not 
 
50 ANIMAL KINGDOiM. 
 
 even a mouth. They include the Sponges, and a large num- 
 ber of minute species, visible only with the aid of a micro- 
 scope. 
 
 1. SUB-KINGDOM OP VERTEBRATES. 
 
 Class 1. MAMMALS. Warm-blooded animals that suckle 
 their young, as Man, Quadrupeds, Whales. Nearly all are 
 viviparous; a few (as the Opossum and other Marsupials} 
 are semi-oviparous, the young at birth being very immature. 
 
 Class 2. BIRDS. Warm-blooded air-breathing animals, 
 oviparous, having a covering of feathers, and the anterior 
 limbs more or less perfect wings. * 
 
 Class 3. EEPTILES. Cold-blooded air-breathing animals, 
 oviparous, having a covering of scales or simply a naked 
 skin. There are two sub-classes : 1. True Reptiles (as Cro- 
 codiles, Lizards, Turtles, Snakes), which breathe with lungs 
 (or are air-breathing) when young as well as afterward, 
 being, in this respect, like birds and quadrupeds; 2. Amphi- 
 bians (as Frogs and Salamanders), which breathe by means 
 of gills when young, and afterwards become air-breathing, 
 the animal undergoing thus a metamorphosis. 
 
 Class 4. FISHES. Cold-blooded oviparous animals, breath- 
 ing by means of gills, and having a covering of scales or 
 simply a naked skin. There are three prominent groups : 
 
 1. Teliosts (as the Perch, Salmon, and all common fishes), 
 having the scales membranous, the skeleton bony, and the 
 gills attached at only one margin. 
 
 The name is from the Greek teleios, perfect, and osteon, 
 bone, alluding to the skeleton being bony. 
 
 The scales in many are toothed or set with spines about 
 the inner margin (fig. 50), while others have the margin 
 smooth (fig. 49). Fishes having scales of the former kind, as 
 the Perch, have been called Ctenoids by Agassiz (from the 
 Greek kteis, comb)', and those having scales of the latter 
 kind, as the Salmon, etc., Cycloids (from the Greek kuklon, a 
 circle). 
 
FISHES. 
 
 51 
 
 2. G-anoids (as the Gar-pike and Sturgeon), having the 
 scales bony and usually shining, and the skeleton often car- 
 tilaginous. The name is from the Greek ganos, shining. 
 
 Fig. 45 represents one of the ancient Ganoids. The verte- 
 bral column extends to the extremity of the tail, so that the 
 tail-fin is vertebrated, while in modern Gars and Teliosts the 
 
 Fig. 45. 
 
 Palaeoniscus Freieslebeni (X 
 
 vertebral column stops at the commencement of the tail, or 
 the tail-fin is non-vertebrate (fig. 46). Agassis calls the former 
 
 Figs. 46-54. 
 
 51 
 
 GANOIDS (excepting 49,50). Fig. 46, Tail of Thrissops (X K); 47, Scales of Cheirolcpis 
 Traillii (X 12); 48, Palaeoniscus lepidurns (X 6); 48 a, under-view of same; 49, Scale of a 
 Cycloid ; 50, id. of a Ctenoid ; 51, Part of pavement-teeth of Gyrodus Umbilicus ; 52, Tooth of 
 Lepidosteus ; 53, id. of a Cricodus ; 54, Section of tooth of Lepidosteus osseus. 
 
 kind heterocercal, and the latter homocercal. The scales are 
 either rhombic, as in figs. 45, 46, or rounded. Some of these 
 
52 
 
 ANIMAL KINGDOM. 
 
 rhombic bony scales are shown in figs. 47, 48. The teeth 
 (figs. 52, 53) often have a folded or labyrinthine texture or 
 arrangement within, as shown in fig. 54. In one group, the 
 Ganoids have a pavement of teeth in the mouth, as in fig. 51. 
 3. Selachians (as the Sharks and Bays), having a hard 
 skin, often rough with minute points, the skeleton more or 
 
 Figs. 55-65. 
 
 SELACHIANS. Fig. 55, Spinax Blainvillii (X V%) ; 56, Spine of anterior dorsal fin, natural size ; 
 57, Cestracion Philippi (X ^); 58, Tooth of Lamna elegans; 59, Tooth of Carcharodon an- 
 gustidens ; 60, Notidanus primigenius ; 61, Hybodus minor ; 62, Hyb. plicatilis ; 63, Month 
 of Cestracion, showing pavement-teeth of lower jaw ; 64, Tooth of Acrodus minimus ; 65, 
 Tooth of Acrodus nobilis. 
 
 less completely cartilaginous, and the gills attached by both 
 margins. The name is from the Greek selachos, cartilage. 
 
ARTICULATES. 53 
 
 Fig. 55 represents, much reduced, one of the order (a 
 JSpinax), having the mouth, as usual, on the under surface 
 of the head, and remarkable for the spine before each of the 
 back fins : one of the spines is shown, natural size, in fig. 56. 
 Fig. 57 is an outline of another Selachian, of the genus Ces- 
 tracion, living in the vicinity of Australia, peculiar in having 
 the mouth at the extremity of the head, and also in the 
 teeth .of the mouth having in part the form and appearance 
 of a pavement, as shown in fig. 63. Figs. 58 to 62 are teeth 
 of different Selachians related to the Sharks ; and figs. 64, 
 65, pavement-teeth of Cestraciont species. The Cestraciont 
 Selachians were once very common ; but now the only living 
 species known are confined to Australasia. 
 
 2. SUB-KINGDOM OF ARTICULATES. 
 
 Among Articulates there are three classes; one, including 
 the species adapted to live on land, and which, for this pur- 
 pose, breathe by means of air-vessels branching through the 
 body, and two, of species adapted to live in water, and, 
 therefore, having gills. 
 
 1. LAND- ARTICULATES, or the class of Insecteans. There 
 are three orders or grand divisions of Insecteans : namely, 
 1. Insects; 2. Spiders ; 3. Myriapods (or Centipedes). 
 
 2. WATER- ARTICULATES, including the two classes 1. 
 Crustaceans (as Crabs, Lobsters, etc.), and 2. Worms. 
 
 Crustaceans. A knowledge of the principal subdivisions 
 of Crustaceans is especially important to the student in 
 geology. There are three orders : 
 
 1. The Decapods, or W-footed species, as the Crab (fig. 67), 
 Lobster, Shrimp. 
 
 2. The Tetradecapods, or \-footed species, as the Sow-bug 
 (fig. 68), found in damp places under logs, the Sand-flea of 
 sea-shores among drift sea-weed (fig. 69), etc. 
 
 3. The Entomostracans, or inferior species, having the feet 
 defective, as the Cyclops and related species (figs. 71, 72), 
 
54 
 
 ANIMAL KINGDOM. 
 
 Daphnia, Limulus or Horse-shoe, the Cypris, and other Ostra- 
 coids (fig. 74). These Ostracoids are generally minute spe- 
 
 ARTICULATES. 1. Worms: 66, Arenicola piscatonim, or Lob-worm (X %) 2. Crustaceans: 
 67, Crab, species of Cancer; 68, an Isopod, species of Porcellio; 69, an Amphipod, species 
 of Orchestia; 70, an Isopod, species of Serolis (X /) ^1, 72, Sapphirina Iris; 71, female, 
 72, male (X 6); 73, Trilobite, Calymene Blumenbachii; 74, Cythere Americana, of the 
 Ostracoid family (X 12); 75, Auatifa, of the Cirriped tribe. 
 
 cics, having a shell like that of a bivalve Mollusk, as fig. 74 
 shows; but inside of the shell, instead of an animal like a 
 clam, there is one more like a shrimp, with jointed legs. The 
 name is from the Greek ostrakon, shell, the word from which 
 oyster is derived. 
 
 Among Entomostr acans, there are also the Barnacles and 
 other Cirripeds, one of which is represented in fig. 75. 
 
 Trilobites (fig. 73) are Crustaceans related to the Ento- 
 mostracans, though more like the Tetradecapods (figs. 68, 70) 
 in form. They may be intermediate between the two orders. 
 The tribe is now extinct. 
 
 3. SUB-KINGDOM OF MOLLUSKS. 
 
 There are two grand divisions or classes of Mollusks : 
 1. The Ordinary Mollusks, as the Clam. Snail, and Cuttlefsh; 
 and, 2, the plant-like or Anthoid Mollusks, many of which are 
 attached by stems, like flowers, and some have an external 
 
MOLLUSKS. 
 
 55 
 
 resemblance to flowers (figs. 84, 85), though not radiate 
 internally like true Eadiate animals. 
 
 1. Ordinary Mollusks. There are three orders: 1. Cepha- 
 lopods: having the head surrounded by arms, and large 
 eyes ; the shell, when any exists as an external covering for 
 the body, is, with a rare exception, divided internally by 
 
 85 
 
 MOLLUSKS. 1. Cephalopods : fig. 76, Nautilus, showing the ^partitions in the shell and the 
 animal in the outer chamber. 2. Gasteropods: 77, Helix. 3. Ptercpods: 78, Cleodora. 4. 
 Conchifers: 79,80; 81, the oyster. 5. Brachiopnds : 82, Lingula, on its stem; 83, Tere- 
 bratula, showing the aperture from which the stem for attachment passes out. 6. JBryo- 
 zoans: 84, Eschara,with the animals a little enlarged; 85, one of the animals out of the 
 shell, more enlarged. 
 
 cross-partitions into a series of chambers, whence they are 
 called chambered shells, as in the Nautilus (fig. 76) and Am- 
 monite (fig. 282). A few have an internal chambered shell ; 
 others an internal straight bone, which has sometimes a 
 conical cavity. The name is from the Greek kephale, head, 
 and pous, foot. 
 
 2. Cephalates: having a head w^ith distinct eyes, but no 
 arms around it, and usually a spiral shell, if any; as the 
 Snail (fig. 77) and other Univalves. The name is from the 
 
56 ANIMAL KINGDOM. 
 
 Greek kephale, head. The species of one division that con- 
 taining the Snail and all ordinary Univalves are called 
 Gasteropods, from the Greek, implying that they crawl on 
 their belly, this part acting, therefore, as a foot. In an- 
 other division, they have a pair of wing-like oars for swim- 
 ming, and these are called Pteropods (fig. 78), from the Greek 
 pteron, wing, and pous, foot. 
 
 3. Acephals : having no prominent head, and only imper- 
 fect eyes if any ; and the shell commonly of two parts called 
 valves, whence the common name of most of the species, 
 Bivalves, as the oyster, dam (figs. 79-81). These species are 
 called Conchifers, from the Latin concha, shell, and/ero, I bear. 
 They have thin lamellar gills either side of the body, whence 
 they are often called also JLamellibranchs, from lamella, a 
 plate, and branchia, a gill. 
 
 In fig. 79, showing the inside of a valve, 1, 2 are impressions 
 of the two great muscles by which the animal closes the 
 shell, and p p is the impression of the margin of the mantle 
 or pallium, and called the pallial impression. This mantle 
 is a thin membrane lying next to the shell; the gills are 
 between it and the body of the Mollusk. In fig. 80, the 
 pallial impression p p has a deep bend or sinus opening 
 towards the back margin of the valve. Shells having this 
 sinus in the impression are described as sinupallial, and 
 those without it as integripallial. In fig. 81, of the oyster, 
 there is but one large muscular impression (at 2). 
 
 2. Anthoid Mollusks. These are of three orders : 
 
 1. Brachiopods : species (figs. 82, 83) having a bivalve 
 shell, like the Conchifers, but one whose form is sym- 
 metrical either side of a middle line ; that is, if a line be 
 dropped from the beak to the opposite edge (as from b to a 
 in fig. 83), t-he parts of the shell on the two sides of the line 
 will be equal. A line similarly drawn in the Conchifers 
 divides the valve unequally (as in fig. 79). The animals have 
 two spiral arms within, which serve as gills. The name 
 
RADIATES. 
 
 57 
 
 Brachiopod, from the Greek brachion, arm, and pous, foot, 
 refers to these arms. 
 
 2. Ascidians : species with a leathery or fleshy exterior, 
 and no shell, and hence hardly recognized among fossils. 
 
 3. Bryozoans : species of minute size, making often cellular 
 corals which, though often in thin plates or incrustations, 
 sometimes delicately branch like a moss, whence the name, 
 from the Greek bruon, moss, and zoon, animal. They include 
 the Cellepores, Flustras, etc. 
 
 4. SUB-KINGDOM OP EADIATES. 
 There are three grand divisions of Eadiates : 
 
 90 Figs. 86-95. 
 
 RADIATES. 1. Echinoderms: 86, Echinus, the spines removed from half the surface (X %)', 
 87, Star-fish, Palreaster Niagarensis; 88, Crinoid, Encrinus liliiformis; 89, Crinoid, of the 
 family of Cystideans, Callocystites Jevvettii. 2. Acalephs: 90, a Medusa, genus Tiaropsis; 
 91, Hydra (X 8); 92, Syncoryna. 3. Polyps: Fig. 93, an Actinia; 94, a coral, Dendrophyl- 
 lia; 95, part of a branch of a coral of the genus Gorgonia, showing one of the polypa 
 expanded. 
 
 1. Echinoderms (figs. 86-89) : having a more or less hard 
 exterior, which is often covered with spines whence the 
 
53 ANIMAL KINGDOM. 
 
 name, from echinus, a hedgehog, and derma, skin. The mouth 
 opens downward in all species except the Crinoids. Among 
 them there are (1) Echinoids, in which the exterior is a solid 
 shell covered with spines, and the mouth opens downward 
 (fig. 86 the spines are removed from half of the shell) ; (2) 
 The Asterioids, or Star-fishes, in which the exterior is rather 
 stiff, but still flexible, so that the animal flexes it in its 
 movements (fig. 87) ; (3) Crinoids, w r hich are much like Star- 
 fishes, but have a stem like a flower (figs. 88, 89). 
 
 2. Acalephs (figs. 90-92) : having a soft, flexible body, 
 usually of a jelly-like aspect, though rather tough, and mov- 
 ing, when free, with the mouth downward, as the Medusce 
 (fig. 90). Some of the species called Hydroid Acalephs (figs. 
 91, 92), in one of their stages, if not through all, look like 
 Polyps ; and some of these Acalephs form corals, like the 
 Polyps. The other species are too soft to be common a 
 fossils. 
 
 3. Polyps (figs. 93-95) : having a soft body usually attached 
 to a support ; a mouth opening upward ; one or more rows 
 of tentacles arranged about the margin of a disk (somewhat 
 like the petals of an Aster around its central disk) ; and the 
 mouth situated at the centre of the disk, as in fig. 93. Most 
 corals are made by Polyps. The coral is secreted within the 
 polyp in the same manner as bones are secreted within other 
 animals. Figs. 94, 95 represent portions of living corals with 
 the polyps expanded. The number of rays in the cells of 
 modern corals called Actinoids is a multiple of six; and 
 that in the more ancient corals, called Cyathophylloids, is a 
 multiple of four. 
 
 5. PROTOZOANS. 
 
 The principal groups of Protozoans important to the 
 geologist are three : 
 
 1. The Sponges. The sponges contain in their tissues 
 great numbers of minute spicules, which are, in nearly all 
 species, siliceous; and these siliceous spicules are found fossil. 
 
ANIMAL KINGDOM. 
 
 59 
 
 2. The Rhizopods, which make minute calcareous shells 
 consisting usually of many combined cells. They are often 
 called Polythalamia, from their many cells, and Foraminifera, 
 from the existence of minute perforations through the shells. 
 Some of the species, magnified from 10 to 20 times (except- 
 ing the last two, which are natural size), are represented in 
 figs. 96-109. 
 
 Fijrs. 96-109. 
 3,-~ * 98^=^ 99 , 
 
 RHIZOPODS. Fig. 96, Orbulina universa; 97, Globigerina rubra; 98, Textilaria globulosa 
 Ehr.; 99, Rotalia globnlosa; 99 o, Side-view of Rotalia Boncana; 100, Grammostomum 
 phyllodes Ehr.; 101, Frondicularia annularis; 102, Triloculina Josephina; 103, Nodosaria 
 vulgaris; 104, Lituola nautiloides; 105, a, Flabellina rugosa; 106, Chrysalidina gradata; 
 107, a, Cuneolimi Pavonia; 108, Nummulites numrmilaria ; 109 a, 6, Fusulina cylindrica. 
 
 3. Polycystines, which make minute siliceous shells, con- 
 sisting of many united cells (figs. 110-112). They differ 
 
 Fi ;s. 110-112. 
 
 10 
 
 12 
 
 POLTCYSTINES. Fig. 110, Lychnocaninm Lucerna (XlOO); 111, Eucyrtidium Mongolfieri 
 (X 100) ; 112, Halicalyptra fimbriata (X 75). 
 
 from the Ehizopods, further, in having the arrangement of 
 the cells radiate, and not spiral or alternate. 
 
 6* 
 
60 CRYPTOGAMS. 
 
 II. VEGETABLE KINGDOM. 
 
 The vegetable kingdom is not divisible into sub-kingdoms 
 like the animal; for all the species belong to one grand type, 
 the Badiate, the one which is the lowest of those in the ani- 
 mal kingdom. The higher subdivisions are as follow : 
 
 I. CRYPTOGAMS. Having no distinct flowers or proper 
 fruit, the so-called seed being only a spore, that is, a simple 
 cellule without the store of nutriment (albumen and starch) 
 around it which makes up a true seed ; as Ferns, Sea-weed. 
 They include 
 
 1. Thallogens. Consisting wholly of cellular tissue ; grow- 
 ing in fronds without stems, and in other spreading forms ; 
 as (1) Algse, which include Sea-weeds and also the Confervas 
 or frog-spittle, and many allied fresh-water plants; (2) 
 Lichens, the dry grayish-white and grayish-green plants 
 that cover stones, logs, &c. 
 
 The Marine Algce, or Sea-weeds, that are found fossil, and 
 are not microscopic in size, are mostly of the tough leathery 
 kinds, related to the modern Fuci. They are often called 
 by the general term of Fucoids, signifying resembling Fuci. 
 
 2. Anogens. Consisting wholly of cellular tissue; growing 
 up in short, leafy stems ; as (1) Musci, or Mosses ; (2) Liver- 
 worts. 
 
 3. Acrogens. Consisting of vascular tissue in part, and 
 growing upward; as (1) Ferns or Brakes; (2) Lycopodia 
 (Ground-Pine) ; (3) Equiseta (Horse-tail or Scouring Bush) ; 
 and including many genera of trees of the Coal period 
 related to these groups. 
 
 The Microscopic Algse are sometimes called Protophytes. 
 They are mostly one-celled species : a few consist of a small 
 number of cells united ; and these pass into other species, 
 like common mould, which are in threads, simple or branched, 
 made up of many cells. The kinds found fossil are the fol- 
 lowing : 
 
VEGETABLE KINGDOM. 
 
 61 
 
 1. Diatoms. Species having a siliceous shell, often quite 
 beautiful in form. Some of the shells are represented, highly 
 magnified, in figs. 117 to 122. They grow so abundantly in 
 some waters, fresh or salt, as to produce large siliceous beds, 
 the material of which is an excellent polishing powder and 
 has long been used for this purpose. 
 
 2. Desmids. Species making no siliceous shell, consisting 
 of one or more greenish cells (figs. 181 to 187, p. 110). These 
 are found fossil in flint and horn stone. 
 
 II. PHENOGAMS. Having (as the name implies) distinct 
 flowers and seed; as the Pines, Maple, and all our shade and 
 fruit trees, and the plants of our gardens. They are divided 
 into 
 
 1. G-ymnosperms. Having the flowers exceedingly simple, 
 and the seed naked, the seed being ordinarily on the inner 
 surface of the scales of cones, and the wood having a bark 
 and rings of annual growth (fig. 113); as the Pine, Spruce, 
 Hemlock, etc. The name Gymnosperm is from the Greek 
 for naked 
 
 PLANTS. Fig. 113, section of exogenous wood ; 114, fibres of ordinary coniferous wood (Pinus 
 Strobus), longitudinal section, showing dots, magnified 300 times ; 115, same of the Austra- 
 lian conifer, Araucaria Cunninghami ; 116, section of endogenous stem. 
 
 Figs. 117 to 122, DIATOMS highly magnified ; 117, Pinnularia peregrina, Richmond, Va. ; 118, 
 Pleurosigma augulatum, id. ; 119, Actinoptychus senarius, id. ; 120, Melosira sulcata, id ; 
 a, transverse section of the same; 121, Grammatophora marina, from the salt water at 
 Stonington, Conn. ; 122, Bacillaria paradoxa, West Point. 
 
 The Gymnosperms include (1) the Conifers, or the Pine- 
 tribe of plants, usually called evergreens; and (2) the Cycads, 
 
62 PHENOGAMS. 
 
 or plants related to the Cycas and Zamia, which have the 
 leaves and look of a Palm page 167), although, in fruit and 
 wood, true Gymnosperms. There is a third group of extinct 
 species (which have not existed since the Carboniferous age), 
 called Sigillarice (see p. 128). 
 
 The wood of the Conifers is simply woody fibre without 
 ducts, and in this respect, as well as in the flowers and seed, 
 this tribe shows its inferiority to the following subdivision. 
 The fibres, moreover, may be distinguished, even in petrified 
 specimens, by the dots along their surface as seen under a 
 high magnifier. The dots look like holes, though really only 
 thinner spaces. Fig. 114 shows these dots in the Pinus 
 Strobus. In other species they are less crowded. In one 
 division of the Conifers, called the Araucarice, of much geo- 
 logical interest, these dots on a fibre are alternated (fig. 115), 
 and the Araucarian Conifers may thus be distinguished. 
 
 2. Angiosperms. Having regular flowers and covered seed; 
 growth exogenous, the plants having a bark and rings of 
 annual growth (fig. 113) ; as the Maple, Elm, Apple, Rose, and 
 most of the ordinary shrubs and trees. These plants are 
 called Angiosperms, because the seeds are in seed-vessels ; and 
 also Dicotyledons, because the seed has tw r o cotyledons or 
 lobes. 
 
 The Gymnosperms and Angiosperms make up the division 
 of plants called Exogens, which is so named from the Greek 
 exo, outward, and gennao, to grow, because growth takes place 
 through annual additions of layers to the outside of the trunk 
 between the wood and the bark, as illustrated in fig. 113. 
 
 3 Endogens. Having regular flowers and seed; growth 
 endogenous, the plants being without bark, and showing, in 
 a transverse section of a trunk, the ends of fibres, and no 
 rings of growth (fig. 116V; as the Palms, Rattan, Reed, 
 Grasses, Indian Corn, Lily. The Endogens are Monocotyle- 
 dons; that is, the seed is undivided, or consists of but one 
 cotyledon. 
 
PART III. 
 
 HISTORICAL GEOLOGY. 
 
 HISTORICAL GEOLOGY treats of the order of succession in 
 the strata of the earth's crust, and of the changes that were 
 going on during the formation of each bed or stratum, that 
 is, of the changes in the oceans and the land; of the changes 
 in the atmosphere and climate ; of the changes in the plants 
 and animals. In other words, it is a historical view of the 
 events that took place during the earth's progress, derived 
 from the study of the successive rocks. It is sometimes 
 called stratigraphical geology ; but this term embraces only 
 a description of the nature and arrangement of the earths strata. 
 
 By using the means for determining the order of the 
 several formations mentioned on page 44, and by a careful 
 study of the organic remains (as fossils are often called) 
 contained in the rocks, from the oldest to the most recent, 
 it has been found that a number of great ages in the progress 
 of this life, and in other events of the history, can be made 
 out. 
 
 The following have thus been ascertained : 
 
 (1.) There was first an age, or division of time, when there 
 was no life on the globe ; or, if any existed, this was true 
 only in the later part of the age, and the life was probably 
 of the very simplest kinds. 
 
 (2.) There was next an age when Shells or Mollusks, 
 Corals, Crinoids, and Trilobites, abounded in the oceans, 
 when the continents were almost all beneath the salt waters, 
 
 63 
 
 
64 HISTORICAL GEOLOGY. 
 
 and when there was, as far as has been ascertained, no ter- 
 restrial life. 
 
 (3.) There was next an age when, besides Shells, Corals, 
 Crinoids, Trilobites, and Worms, there were Fishes in the 
 waters, and when the lands, though yet small, began to be 
 covered with vegetation. 
 
 (4.) There was next an age when the continents were at 
 many successive times largely dry or marshy land, and the 
 land was densely overgrown with trees, shrubs, and smaller 
 plants, of the remains of which plants the great coal-beds 
 were made. In animal life there were, besides the kind's 
 already mentioned, various Amphibians and some other 
 Reptiles of inferior tribes. 
 
 (5.) There was next an age when Reptiles were exceed- 
 ingly abundant, far outnumbering and exceeding in variety, 
 and many also in size and even in rank, those of the present 
 day. 
 
 (6.) There was next an age when the Reptiles had dwin- 
 dled, and Mammals or Quadrupeds were in great numbers 
 over the continents; and the size of these Quadrupeds, like 
 that of the Reptiles in the preceding age, was far greater 
 than the size of modern species. 
 
 (7.) After this came Man; and the progress of life here 
 ended. 
 
 The above-mentioned ages in the progress of life and the 
 earth's history have received the following names : 
 
 1. Azoic TIME or AGE. The name is from the Greek a, 
 not or without, and 2de, life. 
 
 2. AGE OF MOLLUSKS, or the SILURIAN AGE. 
 
 3. AGE OP FISHES, or the DEVONIAN AGE. 
 
 4. AGE OF COAL-PLANTS, or the CARBONIFEROUS AGE. 
 
 5. AGE OF REPTILES, or the REPTILIAN AGE. 
 
 6. AGE OF MAMMALS, or the MAMMALIAN AGE. 
 
 7. AGE OF MAN. 
 
 The first of these ages the Azoic stands apart as the 
 
SUBDIVISIONS IN THE HISTORY. 65 
 
 preparatory time for the commencement of the systems of 
 life. The next three ages were alike in many respects, 
 especially in the air of antiquity pervading the tribes that 
 then lived, the shells, crinoids, corals, fishes, coal-plants, and 
 reptiles belonging, to tribes that are now wholly or nearly 
 extinct. The era of these ages has, therefore, been appro- 
 priately called Paleozoic time, the word Paleozoic coming from 
 the Greek palaios, ancient, and zoe, life. 
 
 The next age was ushered in after the extinction of many 
 of the Paleozoic tribes; and its own peculiar life approxi- 
 mated more to that of the existing world. Yet it was still 
 made up wholly of extinct species, and the most prominent 
 of the tribes and genera disappeared before or at its close. 
 This age corresponds to Medieval time in geological history, 
 and is called Mesozoic time, from the Greek mcsos, middle, and 
 zoe, life. 
 
 The next age was decidedly modern in the aspect of its 
 species, the higher as well as lower, although only a few of 
 those of its later epochs survive into the age of Man. It is 
 called Cenozoic time, from the Greek kainos, recent, and zoe, 
 life (the ai of Greek words always becoming e in English, 
 as, for example, in ether, from the Greek aither~). 
 
 The following are, then, the grand divisions of geological 
 time adopted : 
 I. Azoic TIME. 
 
 II. PALEOZOIC TIME, including (1) The Age of Mollusks, 
 or Silurian; (2) The Age of Fishes, or Devonian; (3) The 
 Age of Coal-Plants, or Carboniferous. 
 
 III. MESOZOIC TIME, including the Keptilian Age. 
 
 IY. CENOZOIC TIME, including the Mammalian Age. 
 Y. The AGE OF MIND, or the Human Era. 
 
 The following sections represent the successive formations 
 of the globe, arranged in the order of time, with the subdi- 
 visions corresponding to the Ages and Periods. 
 
 The various strata in the formations of an age are very 
 
66 HISTORICAL GEOLOGY. 
 
 Ages. Fig 123 I'aieozoic. American Periods. Foreign Divisions. 
 
 CARBONIFEROUS AGE. or AGE OP COAL PLANTS. 
 
 
 
 15 Permian. 
 
 Permian. 
 
 , , "|" i' T ' '| ' " ' "I" "" 
 
 
 -~-^^=--^-'-~-^^~'^^^^^ 
 
 
 .-;--..-....--.-.- ..-.".'. -. ..-;.--.,-.-. 
 
 14 Carboniferous, or 
 Coal Measures, 
 
 Carboniferous, or 
 Coal Measures. 
 
 jr^-r^TLT^r-L :--^~:r^r^-^-__ 
 
 
 
 
 \r^--;s--. r r 
 
 
 ^^:ef^^l^fi 
 
 _ 
 
 mmmiimm 
 
 13 Sub-carboniferous. 
 
 Mountain limestone. 
 
 DEVONIAN AGE. or AGE OF FISHES. 
 
 : 
 
 ::-::-::-:-:-:::-:: :->:: i :f :c 
 
 12 Catskill. 
 11 Chemung. 
 
 Old Red Sandstone. 
 
 '-;:: -.-:-:-;- % :->:'.->:->"->". . *'>~.-w^ 
 
 " " ". .'-'-.-. ".V-. '/.'.'.'.'-. '-.-.'-.".'.'. .-.-..- -._-. . .-" -."-'-.V-. -.'"-.'-.'-/-/."" 
 
 
 10 Hamilton. 
 
 
 
 - 
 
 
 9 Corniferous. 
 
 ^ipMM^^^iS^ 
 
 . .;. : .v. : . : . ; .v. : . : .. ; . : . : . ; . : . ; . : . ; . : .v. x . : . : . : . : . : . : . ; . ; . : . : . : .;. ; .v.v. 
 
 8 Oriskany. 
 
 SILURIAN AGE, or AGE OF MOLLUSKS. 
 
 
 ' .1 |-i ,' i ' T ^-r- 
 
 1 Lower Helderberg. 
 
 Ludlow beds. 
 
 -T^r-rr 
 
 6 Salina. 
 
 
 j2 
 
 T /. . -. -. ... ., ... -.-.-,...',.. 
 
 5 Niagara. 
 
 Wenlock beds. 
 
 x%-"-'-"-"-"-"-"-"->M-x%-y.v 
 
 
 
 
 - --' -~ ^ - - _--T^-_ --_^r^~ ^^ 
 
 4 Hiidsop. 
 
 Caradoc sandstone. 
 Bala limestone. 
 Lhmdeilo flags. 
 
 Primordial. 
 
 
 =P=P=^^^ 
 
 3 Trenton. 
 
 
 ::^]-v:~ T-^ - - ;"r^=^p:=r 
 
 
 
 2 Potsdam, or 
 Primordial. 
 
 
 Azoic. j 
 
 X .'T n A'/'/x <VA^ N A. ^,-7' ,"\ ' C> vV- 
 
 
SUBDIVISIONS IN THE HISTORY 67 
 
 Ages. Fig. 123 (continued). Periods^ Foreign Subdivisions. 
 
 Quarteruary, or 
 Pleistocene. 
 
 Pliocene. 
 Miocene. 
 Eocene. 
 
 Triassic. 
 
 Upper Cretaceous. 
 Middle Cretaceous. 
 Lower Cretaceous. 
 
 Wealden. 
 
 Oolite. 
 
 Lias. 
 
 Keuper. 
 Muschelkalk. 
 
 Bunter-sandstein. 
 
 diversified in character, limestones being overlaid abruptly 
 by sandstones, conglomerates, or shales, or either of these 
 last by limestones ; and each may be very different from the 
 following in its fossils. These abrupt transitions in the 
 strata are proofs that there were great changes at times in 
 the conditions of the region where the strata were formed, 
 and the transitions in the kinds of fossils are evidence of 
 
 ' 7 
 
G8 HISTORICAL GEOLOGY. 
 
 great destruction at intervals in the life of the seas. Such 
 transitions, therefore, naturally divide off the ages into 
 smaller portions of time, QY periods t as they are called. By 
 transitions similar in kind, but not so great, periods may 
 often be subdivided into still smaller parts, or epochs. 
 
 In the preceding sections, Azoic is at the bottom, on the 
 left; above it there are the names Silurian, Devonian, and so 
 on; and the names of the Periods, Potsdam, Trenton, etc., 
 dividing off these Ages, on the right. 
 
 , The names of the Periods in the first part of the section 
 (those of the Paleozoic) are derived from the names of Ame- 
 rican rocks. The names on the other part are mostly Euro- 
 pean, as the series of rocks it contains (those of Mesozoic and 
 Ceiiozoic time) are more complete in Europe than in America= 
 
 The map on page 69 represents the distribution of the rocks 
 of the different ages, as surface-rocks, over the United States 
 and Canada. 
 
 The Azoic areas are dotted with short lines. 
 
 The Silurian are lined horizontally. 
 
 The Devonian are lined vertically. 
 
 The Carboniferous are black, or black cross-lined or dotted 
 with white, the black areas being of the Carboniferous period; 
 the cross-lined of the Subcarboniferous ; the dotted, of the 
 Permian. 
 
 The Mesozoic have lines, or lines of dots, inclined from the 
 right above to the left below, thus (/) ; the areas with lines 
 being Triassic or Jurassic, and those with lines of dots Cre- 
 taceous. 
 
 The Cenozoic have lines inclined from the left above to the 
 right below, thus (\); the areas more openly lined on the 
 left border of the map are of fresh-water or brackish- 
 Water origin, and the rest mainly of marine origin. 
 
 The areas left white are of unascertained or doubtful age. 
 
 The Silurian strata may underlie the Devonian, and both 
 Silurian and Devonian the Carboniferous. The black areas 
 
SUBDIVISIONS IN THE HISTORY. 
 
 69 
 
70 
 
 HISTORICAL GEOLOGY. 
 
 of the Carboniferous period do not, therefore, indicate the 
 absence of Devonian and Silurian, but only that the Car- 
 boniferous strata are the surface strata over the region. 
 There may even be exceptions to this remark with regard 
 to the surface strata; for over the areas thus marked Car- 
 boniferous, older rocks may occur in some of the bluffs along 
 the valleys, or occupy small areas in the region, which are 
 too limited to be noted on so small a map. 
 
 The map on page 71 represents the surface-rocks of the 
 State of New York and Canada, the several areas corre- 
 sponding to the periods. For the Silurian, the lines or dots 
 are drawn horizontally, as in the preceding, and for the 
 Devonian, vertically. There is no Carboniferous, except near 
 the southern border of the State of New York. 
 
 No. 1. The Azoic. 
 
 2. The Primordial, or Potsdam Period. 
 
 3. The Trenton Period. 
 
 4. The Hudson Period. 
 
 5. The Niagara Period. 
 
 6. The Salina Period. 
 
 9. The Upper Helderberg Period. 
 
 10 The Hamilton Period. 
 
 11 The Chemung Period. 
 12. The Catskill Period. 
 
 Fig. 125. 
 
 Lower 
 Silurian. 
 
 Upper 
 Silurian. 
 
 Devonian. 
 
 Silurian. 
 
SUBDIVISIONS IN THE HISTORY. 
 
 Geological Map of New York and Canada. 
 
72 AZOIC AGE. 
 
 In the section in fig. 125, the rocks of the successive 
 periods are represented in order, from the Azoic, in northern 
 New York, southwestward to the Coal formation of Penn- 
 sylvania, showing that they succeed one another on the 
 map simply because they come to the surface in succession. 
 The amount of dip and its regularity are greatly exag- 
 gerated in the section; and there is no attempt to give 
 the relative thickness of the beds. 
 
 I. AZOIC TIME, OR AGE. 
 
 1. Rocks: kinds and distribution. 
 
 1. Distribution. The Azoic Age commenced with the 
 origin of the earth's crust, and includes the oldest rocks of 
 the globe. Its formations are those upon which the fos- 
 siliferous rocks of the Silurian and subsequent ages have 
 been spread out, and the material out of which most of these 
 later rocks have been made. 
 
 The Azoic rocks extend around the whole sphere ; but, in 
 general, they are concealed from view by subsequent forma- 
 tions. In North America they are surface rocks over a large 
 area north of the great lakes, the longer branch of which 
 area runs northwest to the Arctic Ocean, and the shorter, 
 northeast to Labrador. The white area on the following 
 map, in what is now British America, is the portion of the 
 continent covered with Azoic rocks. 
 
 The shape is a little like that of the letter Y. There 
 is also a small Azoic area in northern New York (see map, 
 p. 71); another south of Lake Superior; and a few other 
 spots east of the Rocky Mountains. What portion of the 
 Rocky Mountain region, or the country beyond, may be 
 Azoic at surface, is not known. 
 
GEOGRAPHICAL DISTRIBUTION. 73 
 
 In Europe, Azoic rocks are in view in the great iron 
 regions of Sweden and Norway, in Bohemia, and in north- 
 ern Scotland. 
 
 2. Kinds of Rocks. The rocks are mostly crystalline rocks, 
 such as granite, syenite, gneiss, hornblendic gneiss, mica- 
 
 Fig. 127. 
 
 Azoic Map of North America. 
 
 schist, hornblendic, chloritic, and talcose schists, and granu- 
 lar limestone. But besides these there are some hard con- 
 glomerates, quartz-rocks or gritty sandstones, and slates. 
 The beautiful iridescent feldspar called labradorite is a 
 common constituent of some of the crystalline or granitic 
 rocks. 
 
 Along with the rocks there are, in some regions, immense 
 
AZOIC AGE. 
 
 Fig. 128. 
 
 beds of iron ore (, t, i in fig. 128). In northern New York 
 
 there are beds 100 to 700 feet thick. In Missouri there are two 
 
 "iron mountains," as they are called; 
 
 one, the Pilot Knob, is 581 feet high, 
 
 the other 228 feet. Similar iron-ore 
 
 beds occur in Michigan, south of Lake 
 
 Superior. 
 
 3. Disturbance and Crystallization of the Rocks. The layers 
 of gneiss and other schistose rocks, with the included lime- 
 stones, are nowhere horizontal; but, instead of this, they 
 dip at all angles, and are often flexed or folded in a most 
 complex manner. Fig. 129 represents the folded character 
 
 Fig. 129. 
 
 Fig 129, by Logan, from the south side of the St. Lawrence in Canada, between Cascade 
 Point and St. Louis Rapids ; 1, gneiss. 
 
 of the Azoic rocks of Canada. The folded rocks in this 
 figure are overlaid by beds that are nearly horizontal, which 
 belong to the Lower Silurian., 
 
 Owing to the dislocations and uplifts which the rocks 
 have undergone, the iron-ore beds look like veins; and even 
 the strata of crystalline limestone have often a similar vein- 
 like appearance. Where strata have been thrown up so that 
 the layers stand vertical, the included bed of ore will be 
 vertical also, and will descend downward in the same man- 
 ner as a true metallic vein ; and through the breaking and 
 
 * o o 
 
 faulting of the strata, many of those irregularities would 
 result that are so common in veins. 
 
 Gneiss, mica-schist, granular limestone, and other crys- 
 talline rocks have been described on page 23 as metamor- 
 phic rocks, rocks that were once horizontal sandstones, 
 shales, and stratified limestones, and which have been, 
 
DISTURBANCES OF BEDS. 75 
 
 by some process, crystallized. The gneiss and schists in 
 Azoic regions are actually in layers or strata, alternating 
 with one another, as common with ordinary sandstones and 
 shales ; and the ore-beds are conformable to the layers of 
 schist and quartz-rock in which they occur. 
 
 4. Conclusions as to the Origin of the Hocks. The following 
 conclusions hence follow :- (1) That the Azoic rocks here 
 referred to were originally horizontal strata of sandstones, 
 shales, and limestones; (2) That after their formation they 
 were pushed out of place by some great movement of the 
 earth's crust, which uplifted and folded them, so that now 
 they are nowhere horizontal ; (3) That, besides being dis- 
 placed, they were also crystallized, that is, changed into 
 metamorphic rocks. Even the sandstones and conglomerates 
 of the Azoic give evidence by their hardness of the action 
 of the same heat that caused the crystallization of other 
 Azoic strata. 
 
 It is altogether probable that the time of the uplifting 
 and that of the metamorphism were the same. There may 
 have been many such metarmophic epochs in the course of 
 the Azoic age. But, since even the latest beds of the Azoic 
 are thus upturned and crystallized, an extensive revolution 
 of this kind must have been a closing event of the age. Fig. 
 129 shows that the upturning preceded the formation of 
 the lowest Silurian beds, for these lie undisturbed over the 
 folded and crystallized Azoic. 
 
 Below the surface Azoic rocks, there must be others, con- 
 stituting the interior portions of the earth's crust. If the earth 
 were originally a melted globe, as appears altogether pro- 
 bable, the earth's crust is its cooled exterior. Whenever 
 the crust formed, its surface must have been at once worn 
 by the waves, wherever within their reach, and deposits of 
 sand, pebbles, and clay must have been formed ; and in this 
 way the Azoic formations were begun. But at the same 
 time that these surface strata were in progress, the crust 
 
76 AZOIC AGE. 
 
 would have been increasing in thickness within by the cool- 
 ing which was continuing its progress. Of the interior rock 
 of the crust we know little or nothing. 
 
 2, Life. 
 
 The Azoic rocks as far as they have been examined, con- 
 tain no fossils. It is not yet certain, however, that some 
 life may not have existed on the globe before the close of 
 the age. 
 
 There is abundant reason for concluding that if there were 
 any plants, they were only sea-weeds; for none but sea-weeds 
 occur in the overlying Lower Silurian formations. If there 
 were any animal life, it is probable that it included only the 
 minute animalcular forms ; since if shells and corals were in 
 the seas their remains would have been preserved in some 
 of the beds that were least altered by the heat of meta- 
 morphism. 
 
 The graphite in certain Azoic rocks, as in those near 
 Ticonderoga, is sometimes thought to be evidence of the 
 existence of plants, because it is known that in later times 
 graphite has been formed out of the remains of plants. The 
 limestone beds have suggested the idea that there may have 
 been animal life of some kinds; for almost all limestones 
 (see p. 21) are of organic origin. But the evidence with 
 regard to both plants and animals is still doubtful. 
 
 3, General Observations. 
 
 The large Azoic area on the map, p. 73, represents the 
 main portion of the dry land of North America in the later 
 part or at the close of the Azoic age ; for it consists of the 
 rocks made during the age, and is bordered, on its different 
 sides, by the earliest rocks of the next age. It is the outline, 
 approximately, of Azoic North America, or the continent, as 
 it appeared when the Silurian age opened. It is, therefore, 
 the beginning of the dry land of North America, the original 
 
GENERAL OBSERVATIONS. 77 
 
 nucleus of the continent, to which additions were made, in 
 succession, with the progress of tbe ages, until its final com- 
 pletion as the age of Man was opening. The smaller Azoic 
 areas mentioned appear to have been mere islets in the 
 great continental sea. 
 
 Each of the other continents was probably represented 
 at the same time by its spot, or spots, of dry land. All the 
 rest of the sphere, excepting these limited areas, was an 
 expanse of waters. 
 
 The evidence appears also to show that both waters and 
 land were lifeless wastes, except it be that sea-weeds and 
 Protozoans were in the oceans. 
 
 The facts to be presented under the Silurian age teach 
 that the great, yet unmade, continents, although so small in 
 the amount of dry land, were not covered by the dee}) ocean, 
 but only by shallow oceanic waters. They lay just beneath 
 the waves, already outlined, prepared to commence that 
 series of formations the Silurian, Devonian, Carboniferous, 
 and others which was required to finish the crust for its 
 ultimate continental purposes. 
 
 We thus gather some hints with regard to the geography 
 of America in the period of its first beginnings. It is stated, 
 in Genesis, that on the third day the waters were gathered 
 together into one place, and the dry land was made to appear, 
 and also that, as a second work of the same day, plants were 
 called into existence as the first life of the earth. The Azoic 
 age in geology witnessed, with little doubt, the appearance 
 of the first continents and probably of the first plants. 
 
 The outline of the northern Azoic area on the map, p. 73 
 the embryo of the continent is very nearly parallel to 
 that of the present continent. The Azoic lands, both in 
 North America and Europe, are largest in the more northern 
 latitudes. 
 
78 PALEOZOIC TIME. LOWER SILURIAN. 
 
 H. PALEOZOIC TIME. 
 
 PALEOZOIC time includes three ages : 
 
 1. The AGE OF MOLLUSKS, or SILURIAN AGE. 
 
 2. The AGE OF FISHES, or DEVONIAN AGE. 
 
 3. The AGE OF COAL-PLANTS, or CARBONIFEROUS AGE. 
 
 In describing the rocks of these ages over North Ame- 
 rica, and the events connected with their history, there are 
 three distinct regions to be noted, distinct, because in an 
 important degree independent in their history. These are 
 
 1. The Eastern border region, or that near the Atlantic 
 border, including central and eastern New England, New 
 Brunswick and Nova Scotia, and the coast region south of 
 New York. 
 
 2. The Appalachian region, or that now occupied by the 
 Appalachian Mountain chain, from Labrador, on the north, 
 along by the Green Mountains, and the continuation of the 
 heights through New Jersey, Pennsylvania, Yirginia, east- 
 ern Tennessee, and so southwestward to Alabama. 
 
 3. The Interior Continental region, or that west of the 
 Appalachian region, continued over much of the present 
 eastern slope of the Rocky Mountain chain. 
 
 We may have hereafter to recognize a Rocky Mountain 
 region and a Western border region, and others on the north ; 
 but at present the geology of these regions is too imperfectly 
 known to render it necessary. 
 
 I. AGE OF MOLLUSKS, OR SILURIAN AGE. 
 
 This Age is called Silurian, from the region of the ancient 
 Silures in Wales, where the rocks occur. It was first so 
 named by Murchison. 
 
 The Age is naturally divided into Lower and Upper Silu- 
 rian, each corresponding, in America, to three periods, thus : 
 
POTSDAM PERIOD. 79 
 
 1. LOWER SILURIAN. 
 
 1. Potsdam, or Primordial Period. \ 
 
 2. Trenton Period : Bala formation anct Llandeilo flags of 
 England. 
 
 3. Hudson Period: Lower Caradoc, or Upper Llandeilo 
 beds of England. 
 
 2. UPPER SILURIAN. 
 
 1. Niagara Period: Wenlock beds of England, either in 
 part, or wholly. 
 
 2. Salina Period. 
 
 3. Lower Helderberg Period : Ludlow beds of England, 
 or all but their upper portion. 
 
 The Silurian is also sometimes divided as follows : 
 
 1. PRIMORDIAL SILURIAN, or Potsdam Period. The term 
 Primordial signifies first in order, or, in this place, the period 
 of the first life of the globe. 
 
 2. MIDDLE SILURIAN ; corresponding to the remainder of 
 the Lower Silurian. 
 
 3. UPPER SILURIAN. The same as above given. 
 
 1. PRIMORDIAL, OR POTSDAM PERIOD. 
 
 
 
 1. Rocks: kinds and distribution. 
 
 The strata of the Primordial or Potsdam period, in Ame- 
 rica, over the Interior Continental basin, are exposed to view 
 at intervals from New York to the Mississippi River; beyond 
 the river, over some parts of the eastern slopes of the Eocky 
 Mountains; and also in Texas. The area on the map of New 
 York and Canada (p. 71) is that numbered 2, lying next to 
 the Azoic. There is reason to believe, from the many points 
 at which the strata come to the surface (as in Michigan, Wis- 
 consin, Iowa, Missouri, Tennessee, Texas, the I pper Mis- 
 souri region), that they extend over the larger part of the 
 continent outside of the Azoic area represented on the map, 
 
 8 
 
80 PALEOZOIC TIME LOWER SILURIAN. 
 
 p. 73, though concealed by other less ancient strata over 
 most of the surface. 
 
 Through this interior region the lower rocks are mainly 
 a sandstone, called the Potsdam sandstone, from a locality 
 in northern New York. The sandstone beds contain, in 
 many places, ripple-marks (fig. 18, p. 32); mud-cracks (fig. 
 20) ; layers showing the wind-drift and ebb-and-flow struc- 
 ture (figs. 17/, e,); worm-burrows, and also occasionally the 
 tracks of some of the animals of the period. The upper 
 rocks in New York, and in the same latitudes west, are 
 sandstone, containing some carbonate of lime, and called the 
 Calciferous beds ; but more to the south in the Mississippi 
 Yalley the beds are mainly a magnesian limestone, called 
 the Lower Magnesian. 
 
 In the Appalachian region in Yermont, north in Canada, 
 and in Pennsylvania, etc., the rocks are slates overlying 
 sandstone, the whole 20QO to 7000 feet or more thick, 
 exceeding many times the thickness to the west. In the 
 Eastern border region beds of the period occur at Braintree 
 near Boston, and near the Labrador coast. 
 
 In Great Britain the primordial rocks are hard sandstones 
 and slates, called in part the Lingula flags. They are most 
 extensively in view in north and south Wales and in Shrop- 
 shire. A lower portion of the series, of great thickness, 
 consisting of slates and other rocks, has been named Cam- 
 brian by Sedgwick. 
 
 In Lapland, Norway, Sweden, and Bohemia, Primordial 
 strata have been observed. If the strata of later date could 
 be removed from the continents, we should probably find the 
 primordial beds extensively distributed over all the conti- 
 nents. 
 
 2. Life. 
 
 These most ancient of fossiliferous rocks contain no 
 remains of terrestrial life. The plants of the period were all 
 sea-weeds. Among animals, the sub-kingdoms of Radiates, 
 
POTSDAM PERIOD. 
 
 81 
 
 Mollusks, and Articulates were represented by water-species, 
 and by these alone. There is no evidence that there were 
 any Vertebrates. 
 
 The older sandstone abounds in many places in a shell 
 smaller, in general, than a finger-nail, called a Lingula (fig. 
 133). It is the shell of a Mollusk of the tribe of Brachiopods. 
 It stood on a stem, when alive, as represented in fig. 82, p. 
 55. These shells are so characteristic of the beds in many 
 
 Fig. 130, Phyllograptus Typus; 131, 132, Graptolithtis Logani; 133, Lingula prima; 134, 
 Ophileta levata: 135, Leperditia Anna; 136, same, natural size; 137, Paradoxides Harlanl 
 (X l /Q ; 138, Track of a Trilobite (X %). 
 
 regions as to give them the name of Lingula flags, or Lin- 
 gula sandstone. 
 
82 PALEOZOIC TIME LOWER SILURIAN. 
 
 Another tribe very prominent among the earliest of the 
 earth's animals is that of Trilobites, of the sub-kingdom of 
 Artieulates, and cLass of Crustaceans. 
 
 One of the largest species of them is represented in fig. 
 137, reduced to one-sixth the natural length. Its total 
 length, when living, must have been 18 inches or more, and 
 hence it was as large as any living Crustacean. The speci- 
 men figured was found at Braintree south of Boston. It is 
 seen to have had large eyes situated on the head-shield, 
 evidence, as Buckland observed, of the clear waters and 
 clear skies of Primordial time. As no legs are ever found 
 in connection with Trilobites, they are supposed to have 
 had only thin membranous or foliaceous plates for swimming. 
 Fig. 138 shows the track of a large animal found by Logan 
 in the Canada beds (and reduced like fig. 137), which may 
 have been made by one of the great Trilobites as it crawled 
 over the sand. 
 
 Another group, characterizing especially the later half of 
 the period, is that of Graptolites, two specimens of which are 
 shown in figs. 130, 131, and an enlarged view of part of fig. 
 131 in fig. 132. The species are so named from the Greek 
 grapho, I write, in allusion to their having commonly a plume- 
 like form. The fossils are very thin, -and are supposed to have 
 consisted of the cells of minute Radiate animals, allied to the 
 Hydroid Acalephs (p. 58). A great number of species have 
 been described. They appear to have grown like delicate 
 mossy plants densely over the muddy bottom of the sea. 
 
 Among Mollusks, besides Brachiopods, there were also 
 Gasteropoda, one of which is shown in fig. 134. 
 
 Crustaceans were represented also by a few species a little 
 like shrimps in general form, but having foliaceous legs like 
 the Trilobites, and called PhyUopods ; also by Ostracoids, one 
 species of which is shown, enlarged, in fig. 135, and of natu- 
 ral size in fig. 136. These little Ostracoids, though insig- 
 
POTSDAM PERIOD. 83 
 
 niiicant in size, are so abundant in some places as nearly to 
 make up the mass of a slate. 
 
 The existence of marine worms among the earliest animals 
 of the globe, is proved by the great numbers of worm-holes 
 or burrows in the sandstones, now filled with the hard sand- 
 stone like that of the rock. They are very similar to the 
 holes made by such worms in the sands of sea-shores at the 
 present time. One species is called Scolithus linearis. These 
 worm-holes are common in the European as well as Ame- 
 rican Primordial sandstones. 
 
 There were also Crinoids of the sub-kingdom of Radiates 
 (p. 58), for disks from the broken stems of Crinoids are not 
 uncommon. And among Protozoans there were at least 
 Sponges, if not also the minute Ehizopods and Polycystines 
 (p. 59). 
 
 Sponges among Protozoans, Graptolites and Crinoids 
 among Radiates, Brachiopods and some representatives of 
 other tribes among Mollusks, Worms and Trilobites, and a 
 few other Crustaceans, among Articulates, and Sea-weeds 
 among Plants, made up the living species ; and in this Prim- 
 ordial population, Trilobites took the lead. There is as yet 
 no evidence that the dry Primordial hills bore a moss or 
 lichen, or harbored the meanest insect, or that the oceans 
 contained a single fish. 
 
 3. General Observations. 
 
 The ripple-marks, mud-cracks, and tracks of animals pre- 
 served in this most ancient of Paleozoic rocks are records 
 left by the waves, the sun, and the life of the period, as to 
 the extent and condition of the continent in that early era ; 
 and the layers having the wind-drift structure or the ebb- 
 and-flow structure are other evidence of similar import. 
 These markings teach that when the beds were in progress 
 a large part of the continent lay at shallow depths in the 
 sea, so shallow that the waves could ripple its sands ; that 
 
 8* 
 
84 PALEOZOIC TIME LOWER SILURIAN. 
 
 over other portions the surface was a sand-flat exposed at 
 low tide; or a sea-beach, the burrowing-place of worms; 
 or a mud-flat, that could be dried and cracked under the 
 heat of the sun, or in a drying atmosphere; or a field 
 of drift heaps of sands, beyond the reach of the tides, which 
 the winds, now gentle in movement, and now blowing in 
 gales, had gradually built up. 
 
 With such evidences of shallow water or emerged sand 
 in a formation extending widely over the continent, it is a 
 safe conclusion that the North American continent was 
 at the time in actual existence, and probably not far from 
 its present extent; and, although partly below the sea-level, 
 it was generally at shallow depths. The same may prove 
 to have been true of the other continents. There is, in fact, 
 evidence of other kinds which, taken in connection with the 
 above, leaves little doubt that the existing places of the deep 
 ocean and of the continents were determined even in the 
 first formation of the earth's crust in the early Azoic, and 
 that, in all the movements that have since occurred, the 
 oceans and continents have never changed places. 
 
 This preservation of markings, seemingly so perishable, 
 on the early shifting sands, is a very instructive fact. They 
 illustrate part of the means by which the earth has, through 
 time, been recording its own history. The track of a Trilo- 
 bite or of a wavelet is a mould in sand or earth, into which 
 other sands are cast both to copy and preserve it ; for if the 
 waves or currents that succeed are light, they simply spread 
 new sands over the indented surface, without obliterating 
 the mould ; and so the addition of successive layers only 
 buries the markings more deeply and thus protects them 
 against destruction. When, finally, consolidation takes 
 place, the track or ripple-mark is made as enduring as the 
 rock itself. 
 
 After the formation in North America of the great Primor- 
 dial sandstone, there was a change in the condition of the 
 
TRENTON AND HUDSON PERIODS. 85 
 
 surface, especially over the interior of the continent. For 
 limestone strata began then to form where sandstones were 
 in progress before. This change was probably some increase 
 in the depth and clearness of the interior of the continental 
 sea. Along the borders of this sea that is, in New York 
 and along the Appalachian region from Quebec into Vir- 
 ginia the rock was still a sandstone or shale, though often 
 more or less calcareous in its composition. 
 
 The limestone of the interior region is remarkably free 
 from fossils; and if, as is probable, it was of organic origin, 
 it follows either that the fossils were all ground to powder 
 to make the rock, or else they were too minute to need 
 grinding, like the Ehizopods figured on page 59, which 
 seldom exceed the finest grains of sand in size. Now, since 
 such Ehizopods made the strata of chalk at a later age, and 
 since also they constitute at the present time the bed of the 
 ocean over immense areas in both deep and shallow waters, 
 and inasmuch as their existence in the Lower Silurian era 
 has been proved by finding fossils of them (though not in 
 the rock here under consideration), it is certainly possible 
 that the magnesian limestones of the period may have been 
 formed out of the remains of Rhizopods. 
 
 Whether the reasoning here used be regarded as satisfac- 
 tory or not, the above will serve to illustrate the methods 
 of searching into the geography of the ancient world that 
 are within the reach of the geologist. And when the facts 
 are all fully known, there is little reason to doubt that the 
 results arrived at will be in the main right. 
 
 2. TRENTON AND HUDSON PERIODS. 
 
 The Middle Silurian includes the Trenton and Hudson 
 periods of America, and those of the Bala limestone and 
 Llandeilo flags of Great Britain. 
 
86 PALEOZOIC TIME LOWER SILURIAN." 
 
 Rocks: kinds and distribution, 
 
 In the Primordial period of America, there was, first, the 
 spreading out of a great sandstone over the submerged por- 
 tions of the continent ; afterwards, the formation of a lime- 
 stone about the middle of the Interior Continental basin, 
 while sandstones but little calcareous were forming along 
 the northern United States and over the Appalachian 
 region. 
 
 In the next period, called the Trenton, limestones were 
 in progress over the Appalachian region, as well as a very 
 large part of the Interior Continental basin, northeastern, 
 northern, and southern. It was the most universal of all 
 limestone formations. It is numbered 3 on the map, p. 71. 
 
 The rock differs from the Lower Magnesian limestone in 
 being full of fossils, shells, crinoidal remains, corals, etc. ; 
 and often the fossil shells and corals are so crowded together 
 that no spot as large as the end of the finger can be found 
 without one or more of them. In fact, if the portions which 
 seem to be without them are sliced very thin and examined 
 under a microscope, they are found to be made up of frag- 
 ments of fossils. 
 
 The thickness of these rocks in some portions of the Ap- 
 palachian region is 6000 to 8000 feet, or more than ten times 
 the thickness in the larger part of the Interior Continental 
 region. 
 
 The name Trenton is derived from Trenton Falls, north 
 of Utica, New York, where the Trenton limestone is exposed 
 in high bluffs along the banks of the stream. The " Chazy," 
 " Birdseye," and " Black Kiver" limestones are the lower 
 strata, in succession, of the Trenton Period, the Chazy being 
 the oldest. 
 
 In the Green Mountains these limestones are now in the 
 condition of white statuary or building marble; for they 
 are the marbles of the Stockbridge and other quarries in 
 
TRENTON AND HUDSON PERIODS. 87 
 
 Berkshire, Massachusetts, and of those of Vermont. They 
 have been altered or metamorphosed, in this part of the 
 Appalachian region, into a crystalline rock, or, in other 
 words, they are metamorphic limestones (see p. 21). In the 
 process of change they have lost all their fossils, excepting 
 a rare example, as at Sudbury, Yermont. Other associated 
 rocks in the same region are also metamorphic, or more or 
 less crystalline. 
 
 Before the close of the Lower Silurian that is, in the 
 Hudson period the area of limestone-making had again 
 contracted. Over the Appalachian region in Pennsylvania, 
 and in the northern portion of the Interior Continental region, 
 that is, through New York State and the same latitudes 
 to the westward, the rocks are shales and shaly sandstones; 
 while in Ohio and some other States beyond they consist of 
 shales and limestones, or shaly limestones. The Utica shale 
 and Lorraine shale of central New York are of this period 
 (see No. 4, on the map, p. 71). 
 
 The rocks of the Middle Silurian, in Great Britain, are 
 shales and shaly sandstones, with but little limestone. The 
 Llandeilo flags are shaly sandstones ; and, together with the 
 associated shales, they have a thickness of many thousand 
 feet. Above them there are the Caradoc sandstone of Shrop- 
 shire and the Bala formation the latter including some 
 limestone in Wales. In Scandinavia there are limestone 
 formations, overlaid by slates and flags ; in Bussia and the 
 Baltic provinces part of the Interior Continental portion 
 of the Eastern Continent the rocks are mainly limestones. 
 
 2. Life. 
 
 The life of the Middle Silurian, like that of the Primordial 
 period, was, as far as evidence has been collected from the 
 American or foreign rocks, wholly marine : no trace of a 
 terrestrial or fresh-water species of plant or animal has 
 been found. 
 
88 PALEOZOIC TIME SILURIAN. 
 
 The plants were sea-weeds alone. 
 
 All the sub-kingdoms of animals were represented, with the 
 exception of the Vertebrates. Among Radiates there were Corals 
 and Crinoids; among Mollusks, representatives of all the 
 several orders; among Articulates, the water-divisions, 
 AYorms and Crustaceans. 
 
 1. Radiates. Fig. 139 represents one of the Corals. Its 
 shape is that of a curved cone, a little like a short horn, the 
 small end being the lower. At top, when perfect, there is 
 a cavity divided oif by plates radiating from the centre. 
 Such corals are called Cyathophylloid corals, from the Greek 
 kuathos, cup, and phullon, leaf, alluding to the cup full of 
 radiating leaves or plates. When living, the coral occupied 
 the interior of an animal similar to that represented in fig. 
 94 or 95. 
 
 Another kind of coral, of a hemispherical form, and made 
 up of very fine columns, is represented in figs. 140, 141, the 
 latter showing the interior appearance. It is called Chcetetes 
 Lycoperdon. Another, of coarser columns, each nearly a 
 sixth of an inch in diameter, is called the Columnaria alveo- 
 lata. In a transverse section the columns are divided off by 
 horizontal partitions. Masses of this coral have been found 
 which weigh each between two and three thousand' pounds. 
 
 Fig. 142 shows the form of one of the Crinoids, though 
 the stem on which it stood is mostly wanting, and the arms 
 are not entire. The mouth was in the centre above, and the 
 animal was like a star-fish with branching arms, turned 
 bottom-upward, and standing on a jointed stem. There 
 were also true star-fishes in the seas. 
 
 2. Mollusks. rAmong Mollusks, Bryozoans were very com- 
 mon : the fossils are small cellular corals : one is shown in 
 fig. 143, and a portion, enlarged, in fig. 144. Brachiopods 
 were still more characteristic of the period, and occur in 
 vast numbers. Fig. 145 is 0. testudinaria ; fig. 146, 0. occi- 
 dentalis; fig. 147, Leptcena sericea. There were also some 
 
TRENTON AND HUDSON PERIODS. 
 
 89 
 
 Conchifers, as fig. 148, Aviculaf Trentonensis ; and some 
 Gasteropoda, as fig. 149, Pleurotomaria lenticularis. Shells 
 
 Fig. 139-151 
 
 RADIATES. Fig. 139, Petraia Corniculum; 140, 141, Chaetetes Lycoperdon; 142, Lecanocrinus 
 elegans. MOLLUSKS : Figs. 143, 144, Ptilodictya fenestrata; 145, Orthis testudinaria ; 146, 
 Ortlris occidentalis ; 147, Leptrcna sericea ; 148, Avicula (?) Trentonensis ; 149, Pleurotomaria 
 lenticularis; 150, Orthoceras juncetiin. ARTICULATES: Fig. 151, Asaphus (Isotelus) gigas. 
 
 of Cephalopoda were especially common under the form of 
 a straight or curved horn with transverse partitions. Fig. 
 150, Orthoceras junceum, represents a small species. One 
 kind had a shell 12 or 15 feet long and nearly a foot in 
 diameter. The word Orthoceras is from the Greek orthos, 
 straight, and keras, horn. 
 
 There were some species also of the genus Nautilus. 
 
 3. Articulates. Fig. 151 represents one of the large Trilo- 
 bites of the Trenton rocks, the Asaphus gigas, a species 
 
90 PALEOZOIC TIME. 
 
 sometimes found a foot long. Another Trilobite is the Caly- 
 mene Blumenbachii, of Europe, represented in fig. 73, p. 54, 
 very similar to the C. senaria of the American rocks. 
 
 While Trilobites appear to have been the largest and 
 highest life of the Primordial seas, Cephalopods, of the 
 Orthoceras family, far exceeded Trilobites in both respects 
 in the Trenton period. The larger kinds must have been 
 powerful animals to have borne and wielded a shell 12 
 or 15 feet long. Although clumsy compared with the fishes 
 of a later age, they emulated the largest of fishes in size, and 
 no doubt also in their voracious habits. Crustaceans, in their 
 highest divisions, as the Crabs, may perhaps be regarded 
 by some as of superior rank to Cephalopods. But Trilobites, 
 of the inferior division of Crustaceans, without proper 
 legs, living a sluggish life in slow movement over the sands 
 or through the shallow waters, or skulking in holes, or 
 attached like limpets to the rocks, were far inferior species 
 to the Cephalopods. 
 
 3. General Observations. 
 
 1. Geography, The wide continental region covered in 
 the Trenton period by the Trenton limestone formation 
 stretching over the Appalachian region on the east, and 
 widely through the Interior basin, must have been through- 
 out a clear sea, densely populated over its bottom with 
 Brachiopods, Corals, Crinoids, Trilobites, and the other life 
 of the era. It may, however, have been a shallow sea ; for 
 the corals and beautiful shells of coral reefs live mostly 
 within 100 feet of the surface. 
 
 During the next, or Hudson period, the same seas, espe- 
 cially on the north, became less free from sediment, through 
 some change of level or of coast-barriers, and consequently 
 much of the former life disappeared, and other kinds sup- 
 plied their places, adapted to impure waters or to muddy 
 bottoms. 
 
LOWER SILURIAN. 91 
 
 2. Disturbances during the lower Silurian, and at its Close. 
 (1.) Igneous ejections in the Lake Superior district. Before 
 the close of the Primordial period there were extensive 
 igneous ejections through fractures of the earth's crust 
 in the vicinity of Lake Superior, about Keweenaw Point 
 and elsewhere, and probably to some extent also over 
 the bottom or area of the lake itself, for this is indi- 
 cated by the dikes and columnar trap of Isle Eoyale, an 
 island in the lake. These rocks, which were melted when 
 ejected, now stand, in many places, in bold bluifs and ridges; 
 and mixtures of scoria and sand make up some of the con- 
 glomerate beds of the region. The sandstones, penetrated 
 by the dikes of trap, and made partly before and partly after 
 the ejection, have a thickness in some places of six or eight 
 thousand feet. There appears to have been a sinking of the 
 region equal to the thickness of the beds, in addition to the 
 igneous ejections. The great veins of native copper of the 
 Lake Superior region are part of the results of this period 
 of disturbance. 
 
 (2.) Emergence of the region of the Green Mountains. The 
 changes from deep to shallow seas, or partly emerged flats, 
 during the Silurian era, are evidence that changes of level, 
 by gentle movements or oscillations in the earth's crust, 
 were going on throughout it. But after the Lower Silurian 
 had closed, or toward its close, there appear to have been 
 greater and more permanent changes. The valley of Lake 
 Champlain and the Hudson, as shown by Logan, probably 
 dates from this time. The Green Mountains, though not 
 raised to their full height, then became stable dry land, like 
 the Azoic regions on the map, p. 73. That they were not 
 dry land before, is shown by the Trenton limestones in their 
 structure, for these are of marine origin ; and that their 
 western side and summit were above the water from and 
 after this time, is indicated by the fact that the formations 
 of the Middle Silurian are the latest that were there formed. 
 
92 PALEOZOIC TIME. 
 
 Upper Silurian and Devonian rocks exist over New Eng- 
 land on the east, and over much of the State of New York 
 on the west (see map, p. 71), but not about the top or 
 western side of this range. 
 
 The Green Mountains appear, therefore, to have been the 
 portion of the great Appalachian chain which first became 
 stable land. 
 
 The vast thickness of the several Lower Silurian forma- 
 tions along the course of the Appalachian chain, as men- 
 tioned on pages 80, 86, and the contrast in this respect with 
 the Interior Continental region, are indications that prepa- 
 ration was making throughout the Appalachian region which 
 were to result ultimately in mountains : the raising of part 
 of the Green Mountains above the sea-level, though it may 
 have been but to a very small height, was the commence- 
 ment of the elevation of the Appalachian chain. 
 
 3. Life. (1.) Progress. There is no evidence that the 
 system of life in its progress during the Primordial and 
 Middle Silurian had so far advanced as to include a terres- 
 trial species, or the lowest of Vertebrates. Trilobites held 
 the first position in the former of these eras, Orthocerata 
 and other Cephalopods in the latter. 
 
 It was the Age of Mollushs ; and while Cephalopods took 
 the lead in the life of the world, all the other orders of Mol- 
 lusks had their representatives. No other sub-kingdom was 
 as well displayed in its several grand divisions, not even that 
 of the Eadiates. Among Articulates, there were neither 
 Myriapods, Spiders, nor Insects; for these are essentially 
 terrestrial animals, and the first species of them thus far 
 discovered are of the Devonian age. 
 
 (2.) Exterminations and Creations. Among. the genera of 
 the Lower Silurian, only five have living species. These 
 are Lingula, Discina, Rhynchonella, and Crania among 
 Brachiopods, and Nautilus among Cephalopods. These 
 genera of long lineage thus reach through all time from 
 
LOWER SILURIAN. 93 
 
 the beginning of the systems of life. All other genera 
 disappear, some at the close of the Primordial, others at 
 that of the Trenton or Hudson period, or even at the 
 termination of subordinate epochs within these periods. 
 
 The extermination of species took place at intervals 
 through the periods, as well as at their close; though the 
 latter were most universal. With the changes from one 
 stratum to another there w r ere disappearances of some 
 species, and with the changes from one formation to 
 another, still larger proportions became extinct. No Prim- 
 ordial species are known to occur in the Trenton period; 
 very few of the species of the earlier epoch of the Trenton 
 survive into the next epoch ; and very many of those of the 
 Trenton did not exist in the Hudson period. Thus life and 
 death were in progress together, species being removed, and 
 other species being created, as time moved on. 
 
 In the first chapter of Genesis we read that on the fifth 
 day the waters brought forth abundantly the moving creature 
 that hath life; and the rocks declare most decisively that 
 the waters were filled with life when the Silurian age 
 opened, although but the earlier species of the life of that 
 fifth day. The eyes of the Trilobites have been referred to 
 as evidence of sunshine and clear skies in that early era. 
 The existence of so much animal life is itself as good proof 
 of the fact ; for without the sun the systems of life could 
 not have had even the display they presented in the Primor- 
 dial period. It is clear, therefore, that although the first 
 vegetation may have existed in Azoic time, while the seas 
 were unduly warm and while, therefore, the earth was 
 densely shrouded in clouds, as the Zoic ages began the 
 clouds were already broken, and the earth had completed its 
 garniture of sky and " greater and lesser lights." 
 
94 PALEOZOIC TIME. 
 
 3. UPPER SILURIAN ERA. 
 
 1. Subdivisions. 
 
 The Upper Silurian in North America includes three 
 periods : the NIAGARA, the SALINA, and the LOWER HELDER- 
 BERG. The name of the first is from the Niagara Eiver, 
 along which the rocks are displayed; that of the second, 
 from Salina in central New York, the beds being the salt- 
 bearing rocks of that part of the State ; that of the third, 
 from the Helderberg Mountains, south of Albany, where 
 the lower rocks are of this period. 
 
 2. Rocks: kinds and distribution. 
 
 The rocks of the Niagara period are 1, a conglomerate 
 and grit-rock called the Oneida conglomerate, which extends 
 from central New York southward along the Appalachian 
 region, having a thickness of 700 feet in some parts of 
 Pennsylvania; 2, shaly sandstones of the Medina group, 
 which spread westward from central New York through 
 Michigan, and also southward along the Appalachian region, 
 being 1500 feet thick in Pennsylvania; 3, hard sandstones, 
 or flags and shales of the Clinton group, having nearly the 
 same distribution as the Medina formation, though a little 
 more widely spread in the west, and about 2000 feet thick 
 in Pennsylvania ; 4, the Niagara group, occurring in western 
 New York, and extending widely over both the Appalachian 
 and Interior Continental regions ; it consists of shales below 
 and thick limestone above at Niagara, mainly of limestone 
 in the Interior region, and of clayey sandstone or shales in 
 the Appalachian region, where it has a thickness of 1500 
 feet or more. The Niagara is one of the great limestone 
 formations of the continent, existing also in the Arctic 
 regions. 
 
 Ripple-marks and mud-cracks are very common in the 
 
UPPER SILURIAN. 95 
 
 Medina formation. The example of rill-marks figured on 
 page 32 is from its strata in western New York. 
 
 The Salina rocks are fragile clayey sandstones, marlites, 
 and shales, usually reddish in color, and including a little 
 limestone. They occur in New York and sparingly to the 
 westward, being thickest (700 to 1000 feet thick) in Onon- 
 daga county, N.Y. 
 
 The salt of Salina and Syracuse, in central New York, is 
 obtained from wells of salt water 150 to 310 feet deep, which 
 are borings into these saliferous rocks. 35 to 45 gallons of 
 the water afford a bushel of salt, while of sea-water it takes 
 350 gallons for the same amount. No salt is found in solid 
 masses. Gypsum is common in some of the beds. A lime- 
 stone called the Guelph formation overlies the Niagara beds 
 at Guelph and in some other parts of western Canada. 
 
 The Lower Helderberg group consists mainly of limestones, 
 and is the second limestone formation of the Upper Silurian. 
 But the rock is generally impure or earthy, and the forma- 
 tion is mostly confined to the State of New York and to the 
 Appalachian region on the south. 
 
 The section, fig. 152, represents the rocks on the Niagara 
 Eiver at and below the Falls. The falls are at F; the whirl- 
 pool, 3 miles below, at W; and the Lewiston Heights, which 
 front Lake Ontario, at L. Nos. 1, 2, 3, 4 are different sand- 
 Fig. 152. 
 
 Section along the Niagara, from the Falls to Lewiston Heights. 
 
 stone strata belonging to the Medina group; 5, shale, and 
 6, limestone, to the Clinton group; 7, shale, and 8, lime- 
 
96 PALEOZOIC TIME. 
 
 stone, to the Niagara group. (Hall.) The next section (fig. 
 153), from the region south of the eastern part of Lake 
 Ontario, consists as follows : 5 6, Medina group, 5 c, Clinton 
 
 Fig. 153. 
 
 Section of the Salina and underlying strata, from north to south, south of Lake Ontario. 
 
 group, 5 d, Niagara group (shale and limestone), 6, Salina 
 beds. (Hall.) 
 
 In Great Britain, the Upper Silurian rocks are first sand, 
 stones and shales, called, when occurring in South Wales, 
 Llandovery beds, and corresponding to the Medina and Clin- 
 ton groups; above these, the Wenlock limestone group, con- 
 sisting of limestone and some shale (and including in the 
 upper portion the Dudley limestone). These rocks occur as 
 surface-rocks near the borders of Wales and England. Next 
 comes the Ludlow group, of the age of the Lower Helder- 
 berg, and perhaps also of the first part of the American 
 Devonian. 
 
 In Scandinavia, the Gothland limestone is the equivalent 
 of the Niagara. 
 
 3. Life. 
 
 The limestone strata and most of the other beds of the 
 Niagara group are full of fossils; so also are the rocks 
 of the Lower Helderberg period, and the Wenlock and 
 Ludlow formations of Great Britain. The Salina formation 
 is almost wholly destitute of them. 
 
 The life of the era was the same in general features as 
 that of the later half of the Lower Silurian. It was wholly 
 marine. 
 
 The only plants were Algce, or sea-weeds. 
 
 In the Animal Kingdom the sub-kingdom of Radiates was 
 represented by Corals and Crinoids; that of Mollusks, by 
 species of all the grand divisions, among which the Brachio- 
 
UPPER SILURIAN. 
 
 97 
 
 pod and Orthoceras tribes were the most prominent, and 
 especially the Brachiopod, whose shells far outnumber those 
 
 Figs. 154-166. 
 54 
 
 RADIATES : Fig. 154, Zaphrentis bilateralis, Clinton group ; 155, Favosites Niagarensis, Nia 
 gara group*} 156, Halysitea catenulatus, id.; 157, Caryocrinus ornatus, id. MOLLUSKS: 
 Fig. 158, Pentamerus oblongus, Clinton gr.; 159, Orthis biloba (X 2), Niagara gr. and Dud- 
 ley limestone ; 160, Leptama transversalis, id. ; 161, Spirifer Niagarensis, id. ; 162, Rhyn- 
 chonella cuneata, U. S. and Great Britain; 163, Avicula emacerata, Niag. gr.; 164, Cyclo- 
 nenia cancellata, Clinton gr.; 165, Platyceras angulatum, Niag. gr. ARTICULATES: Fig. 
 166, Ilomalonotus delphinocephalus. 
 
 of all other Mollusks ; that of Articulates, by Worms, Ostra- 
 coids, and Trilobites; and before the close of the era, by the 
 new form of Crustaceans represented in fig. 174. 
 
98 
 
 PALEOZOIC TIME. 
 
 1. Radiates. Fig. 154 is a polyp-coral of the Cyathophyl- 
 loid tribe, showing the radiating plates of the interior; fig. 
 155, a species of Favosites, a genus in which the corals have 
 a columnar structure, and horizontal partitions subdivide 
 
 Figs. 167-175. 
 
 .69 
 
 MOLLUSKS: Figs. 167, 168, Pentamerus galeatus; 169, 170, Rhynchonella ventricosa; 171, 
 Spirifer macropleurus ; 172, Tentaculites ornatus; 173, id. enlarged. ARTICULATES; Fig. 
 174, Eurypterus remipes, a small specimen; 175, Leperditia alta. Species all from the 
 Lower Helderberg group. 
 
 the cells within; fig. 156, Halysites catenulatus, called chain- 
 coral; fig. 157, a Crinoid, Caryocrinus ornatus, the arms at 
 the summit broken off; fig. 89, p. 57, another Crinoid of the 
 family of Cystideans, from the Niagara group ; fig. 87, p. 57, 
 a star-fish, also from the Niagara group. 
 
 2. Mollusks. Figs. 158 to 162, different Brachiopods of 
 the Niagara period; figs. 167 to 171, other species charac- 
 teristic of the Lower Helderberg period; figs. 164, 165. 
 Gasteropods of the Niagara period; fig. 172, small slender 
 tubular cones, called Tentaculites^ almost making up the 
 
UPPER SILURIAN. 99 
 
 mass of some layers in the Lower Helderberg ; the form of 
 one of them, enlarged, is shown in fig. 173. 
 
 3. Articulates. Fig. 166, a reduced figure of a common Tri- 
 lobite of the Niagara group, a species of Homalonotus, often 
 having a length of 8 or 10 inches; fig. 174, Eurypterus 
 remipes, of a new family of Crustaceans, commencing in the 
 Lower Helderberg; it is sometimes nearly a foot long; 
 species of the same family occur in Great Britain in the 
 Ludlow beds, and one of them is supposed, from the frag- 
 ments found, to have been 6 or 8 feet long, far surpassing 
 any Crustacean now living; fig. 175, an Ostracoid Crusta- 
 cean, the Leper ditia alta, of unusually large size for the 
 family, modern Ostracoids seldom exceeding a twelfth of 
 an inch in length. 
 
 In the Upper Ludlow beds of Great Britain a few remains 
 of land-plants and of fishes have been found. But, from the 
 similarity of many fossils of the upper part of the Ludlow 
 beds to those of the Upper Helderberg, it is probable that 
 these Upper Ludlow beds, if referred to the American sys- 
 tem of subdivisions, would rank as Devonian. 
 
 4. General Observations. 
 
 1. Geography. On the map, p. 69, the areas over which 
 the Silurian formations are surface-rocks are distinguished 
 by being horizontally lined. It is observed that they spread 
 southward from the northern Azoic. 
 
 South of the Silurian area commences the Devonian, 
 which is vertically lined ; and the limit between them shows 
 approximately the course of the sea-shore at the close of the 
 Silurian age. It is seen that more than half of New York, 
 and nearly all of Canada and Wisconsin, had by that time 
 become part of the dry land ; but a broad bay covered the 
 Michigan region to the northern point of Lake Michigan, 
 for here Devonian rocks, and to some extent Carboniferous, 
 were afterwards formed. The Azoic dry land, the back- 
 
100 PALEOZOIC TIME. 
 
 bone of the continent, had also received additions in a simi- 
 lar manner on its eastern and western sides, through British 
 America.* 
 
 But, with all the increase, the amount of dry land in North 
 America was still small. Europe is proved by similar evi- 
 dence to have had much undry land. The surface of the 
 earth was a surface of great waters, with the continents 
 only in embryo, one large area and some islands represent- 
 ing that of North America, and an archipelago that of 
 Europe. The emerged land, moreover, was most extensive 
 in the higher latitudes. The rivers of a world so small in 
 its lands must also have been small. The lands, too, accord- 
 ing to present evidence, were barren, except perhaps during 
 the closing part of the age. 
 
 The succession of Upper Silurian formations is as fol- 
 lows : (1) The coarse grit called Oneida conglomerate, 
 occurring of great thickness along the Appalachian region, 
 and reaching north to central New York; (2) the Medina 
 sandstone, also very thick along the Appalachian region, 
 and extending northward to central New York, and, besides, 
 spreading westward beyond the limits of that State ; (3) the 
 Clinton group of flags and shales, having the same Appala- 
 chian extension and great thickness, but spreading on the 
 north much farther westward, even to the Mississippi; 
 
 (4) the Niagara group, covering the Appalachian region 
 deeply with sandstone and shales, and New York with shales 
 and limestones, and spreading as 'a great limestone forma- 
 tion through the larger part of the Interior region ; then 
 
 (5) the limited Salina salt-bearing marlites of New York, 
 
 * On the map referred to, page 69, lines of the Silurian and Devonian are 
 seen to extend from the Hudson River southwestward along the Appalachian 
 region. But the outcrop of the Silurian, here represented, is not evidence that 
 there was a strip of dry land along this region from the close of the Silurian 
 era, because there is proof that these Appalachian outcrops are a consequence of 
 the uplift of the Appalachian Mountains, an event of much later date. (p. 155.) 
 
UPPER SILURIAN. 101 
 
 and the Appalachian region southwest, with some cotempo- 
 raneous limestones in Canada; then (6) another limestone, 
 but impure and mostly confined to New York State and the 
 Appalachian region. These facts teach that geographical 
 ^changes took* place from time to time, in the course of the 
 era, corresponding to these several changes in the forma- 
 tions. The clear continental seas of the Trenton period 
 were succeeded by conditions fitted to produce the several 
 arenaceous and argillaceous formations, of varying limits, 
 which followed; and then they were again in existence at 
 the epoch of the Niagara group, when corals, crinoids, and 
 shells covered the bottom of the continental sea and made 
 the Niagara limestone formations. But the pure continental 
 seas in the Niagara epoch were less extended than those of 
 the Trenton; for the Appalachian region, instead of being 
 part of the pure sea and making limestones, was receiving 
 great depositions of sand and clay, as if it were at the time 
 a broad reef, or bank, bordering the Atlantic Ocean. 
 
 The Niagara epoch of limestone-making was followed by 
 the Salina or Saliferous period. As the beds are (1) clays 
 and clayey sands, (2) are almost wholly without fossils, 
 and (3) afford salt, it may be inferred that central New 
 York was at the time a great salt marsh, mostly -shut off 
 from the sea. Over such an area the waters would at times 
 have become too salt to support life, owing to partial evapor- 
 ation under the hot sun, and too fresh at other times, from 
 the rains. Moreover, muddy deposits would have been 
 formed; for they are now common in salt marshes wherever 
 there is, as there was then, no covering of vegetation, and 
 the salt waters would naturally have yielded salt on evapor- 
 ation in the drier seasons. Through an occasional ingress 
 of the sea, the salt waters might have been re-supplied for 
 further evaporation. 
 
 There is direct testimony as to the condition of the land 
 and shallowness of the waters in the regions where many 
 
102 PALEOZOIC TIME. 
 
 of the rocks were in progress; for ripple-marks and mud- 
 cracks are common in some layers, and are positive evidence 
 that the sands and earth that are now the solid .rock were 
 then the loose sands of beaches, sand-flats, or sea-bottoms, or 
 the mud of a salt marsh. Such little markings, therefore, 
 remove all doubt as to the condition of central New York 
 in the Salina period. 
 
 Similar markings indicate, also, the precise condition of 
 the region of the Medina sandstone, showing that there were 
 sand-flats, sea-beaches, and muddy bottoms open to the 
 inflowing sea. Where the rill-marks were made (fig. 19, p. 
 32) the sands of the spot were those of a gently sloping flat 
 or beach ; the waters swept lightly over the sands, dropping 
 here and there a stray shell (as the Lingula cuneata) .or a 
 pebble, which became partly buried; and then, as they 
 retreated, they made a tiny plunge over the little obstacle 
 and furrowed out the loose sand below it. The firmness of 
 the sand, lightness of the shells, and smallness of the fur- 
 rows are proof that the movements, were light. 
 
 The great thickness of the several formations of the Upper 
 Silurian along the Appalachian region leads to many inte- 
 resting conclusions. It has been stated (p. 92) that the 
 Appalachian formations of the earlier Silurian were equally 
 remarkable for their great thickness. The Appalachian 
 region, from the Primordial era onward, was, hence, in strong 
 contrast with the Interior Continental region, where the 
 series of cotemporaneous beds are hardly one-tenth as thick. 
 Taking this into connection with another fact, that very 
 many of the strata among the thousands of feet of Silurian 
 formations in the Appalachian region contain those evidences 
 of shallow water and mud-flat or sand-flat origin above ex- 
 plained, there is full proof that in the Silurian era the region 
 was for the most part, as already suggested, a vast sand- 
 reef, ever increasing by new accumulations under the action 
 of the waves and currents of the ocean It was much of 
 
UPPER SILURIAN. 103 
 
 the time a great barrier-reef lying between the open ocean 
 and th^ Interior Continental sea ; and under its lee, this 
 inner sea, opening southward through the area of the Mexi- 
 can Gulf, was often in the best condition for the growth of 
 the shells, corals, and crinoids of which the great limestones 
 were made. 
 
 While the Appalachian region was alike in its general 
 condition through the earlier and later Silurian, the limits 
 of the formations in progress during these two eras were 
 somewhat different. The Green Mountain portions of the 
 region took no part in the new depositions during the Upper 
 Silurian era. The fact stated on page 91, that it had become 
 part of the comparatively stable and emerged portion of the 
 continent, is thus proved ; for if it had been under water, 
 some Upper Silurian beds would have been formed about its 
 western or central portions. The part of the Appalachian 
 region which participated, during the Upper Silurian era, in 
 the great changes connected with the formation of rocks, 
 extended northward from Pennsylvania into New York, and 
 not along the Green Mountains ; the rocks in the State of 
 New York have great thickness for some distance beyond 
 the Pennsylvania border, but thin out about the centre. 
 
 2. Life. In the Upper Silurian the highest species of the 
 seas and of the world continued to be Mollusks, of the order 
 of Cephalopods. At the same time, Trilobites were the first 
 of Articulates, and sea-weeds the highest of plants.* Corals 
 and Crinoids were the only species of life that had the sem- 
 blance of flowers. These flower-animals foreshadowed the 
 flowers of the vegetable kingdom for ages before any of the 
 latter existed. 
 
 There had been, however, considerable progress in the 
 unfolding of the system of life, through the creation of new 
 species and the introduction of new genera and families, 
 
 * The only exceptions to this remark yet known are alluded to on page 99. 
 
 10 
 
104 PALEOZOIC TIME. 
 
 cotemporaneously with the extinction of the older forms. 
 In the Lower Silurian era at least 1000 species of .animals 
 became extinct in America, and 600 in Great Britain ; and 
 in the Upper Silurian 800, or more, in America. The kind 
 of progress which was exhibited is explained on a future 
 page. 
 
 H. AGE OF FISHES, OK DEVONIAN AGE. 
 
 1. Subdivision. 
 
 The Devonian Age may be divided into two eras, an 
 earlier and a later, or that of the lower and that of the upper 
 formations. The earlier includes the periods ORISKANY and 
 CORNIFEROUS ; the later, the HAMILTON, CHEMUNG, and CATS- 
 KILL. The Oriskany period might with almost equal pro- 
 priety be annexed to the Upper Silurian. The distinction 
 of the Catskill from the Chemung is questioned. 
 
 2. Rocks: kinds and distribution. 
 
 1. Earlier and Later eras. The earlier Devonian is remark- 
 able for a great limestone formation, which spread from 
 New York over a large part of the Interior region, and 
 nearly equalled the Trenton in extent ; while the later has 
 almost no limestones, the rocks being sandstones and shales 
 with some conglomerates. 
 
 2. Oriskany Period. The first of the formations, the Oris- 
 kany sandstone, is a rough-looking, earthy rock. It extends 
 along the Appalachian region, and northward in New York 
 to the vicinity of Oriskany. A rock of the same age occurs 
 also in the Eastern border region in Maine and Nova Scotia. 
 To this succeeds the 
 
 3. Corniferous Period. Its lowest rocks are fragmental 
 beds, called the Cauda-Galli grit and the Schoharie grit, 
 having their distribution along the Appalachian region, 
 
DEVONIAN AGE. 105 
 
 commencing in central and eastern New York and extend- 
 ing southwestward. 
 
 Next follows the great Corniferous limestone, the lower 
 part of which is sometimes called the Onondaga limestone, 
 and the whole often the Upper Helderberg group. It stretches 
 from eastern New York westward to the States beyond the 
 Mississippi. 
 
 The name Corniferous (derived from the Latin cornu, horn) 
 was given it by Eaton, from its frequently containing a kind 
 of flint called hornstone. 
 
 This hornstone differs from true flint in being less tough, 
 or more splintery in fracture, though it is like it in hardness 
 and in consisting wholly of silica. 
 
 The limestone is literally an ancient coral reef. It con- 
 tains corals in vast numbers and of great variety ; and in 
 some places, as near Louisville, Kentucky, at the Falls on 
 the Ohio, the resemblance to a modern reef is perfect. Some 
 of the coral masses at that place are 6 or 8 feet in diameter; 
 and single polyps of the Cyathophylloid corals had in some 
 species a diameter of 2 and 3 inches, and in one, of 6 or 7 
 inches. 
 
 The same reef-rock occurs near Lake Memphremagog on 
 the borders of Yermont and Canada; but the corals have 
 there been partly obliterated by metamorphism. The lime- 
 stone occurs among metamorphic schists, a talcose schist 
 overlying it,, according to Hitchcock. The crystalline rocks 
 extending south through Yermont into Massachusetts, and 
 the granites and gneiss of the White Mountains, are supposed 
 to be altered Devonian sandstones, and shales. 
 
 4. Hamilton Period. The Hamilton formation consists of 
 sandstones and shales, with a few thin layers of limestone. 
 It consists of three parts, corresponding to three epochs : 
 the lower part is called the Marcellus shale; the middle, the 
 Hamilton beds ; and the upper, the G-enesee shale. It has 
 its greatest thickness along the Appalachians. From New 
 
106 PALEOZOIC TIME. 
 
 York it spreads westward, and, in the form of what is 
 called black slate, more properly a black shale (supposed to 
 be of the epoch of the Marcellus shale), it is widely known 
 through the Interior Continental region. 
 
 The Hamilton beds afford an excellent flagging-stone in 
 central New York and on the Hudson Eiver, which is ex- 
 tensively quarried and exported to other States. 
 
 5. Chemung Period. The Chemung beds are mainly sand- 
 stones, or shaly sandstones, with some conglomerate. They 
 spread over a large part of southern New York, having 
 great thickness in the Catskill Mountains. 
 
 The formation along the Appalachians is 5000 feet thick. 
 It thins out to the west of New York, in Ohio, and Michigan. 
 
 In the following section, taken on a north-and-south line 
 south of Lake Ontario, No. 6 represents the beds of the 
 
 Fig. 176. 
 
 7 9 10 a 
 
 Section of Devonian formations south of Lake Ontario. 
 
 Salina period ; overlaid by 7, the Lower Helderberg lime- 
 stone; 9, the Corniferous, or Upper Helderberg limestone; 
 10, a, b, c, the Hamilton beds ; and 11, the Chemung group. 
 
 6. Catskill Period. The Catskill rocks of Ne^ York have 
 been considered as pertaining to a Catskill period; but recent 
 observations have shown that they are part of the Chemung 
 formation. It is not yet known that the same is true of the 
 sandstones and shales of Pennsylvania, referred to the Cats- 
 kill period, which are stated to have a thickness of 6000 feet. 
 
 In Great Britain, the Devonian rocks have been called 
 the Old Eed Sandstone, the prevailing rock in Wales and 
 Scotland being a red sandstone. This sandstone formation, 
 however, includes marls of red and other colors, and some 
 
DEVONIAN AGE. 
 
 107 
 
 limestone. The distribution in Great Britain is shown on 
 the map, p. 120. In Germany, in the Rhenish provinces, there 
 is a coral limestone very similar to that of North America. 
 
 3, Life. 
 
 1. General characteristics. 
 
 The Devonian of North America, as far as now known, is 
 the era of the first of terrestrial plants, the first of Insects or 
 terrestrial Articulates, and the first, also, of Vertebrates. These 
 early Vertebrates were Fishes, the species that belong to the 
 water. 
 
 2. Plants. 
 
 Figs. 177-179 represent portions of some of the plants. 
 Fig. 179 is a fragment of a, fern, and figs. 177, 178, portions 
 
 Figs. 177-179. 
 
 177 
 
 PLANTS. Fig. 177, Lepidodendrou primsevum, from the Hamilton group; 178, Sigillaria, 
 ibid. ; 179, Noeggerathia Halliana, from the Chemung group. 
 
 of the trees, of the age. The scars or prominences over the 
 surface are the bases of the fallen leaves : a dried branch of 
 a Norway spruce, stripped of its leaves, looks closely like 
 fig. 178f By referring to page 60, it will there be seen that 
 among the Cryptogams there is one order, the highest, or 
 
 10* 
 
108 PALEOZOIC TIME. 
 
 that of Acrogens, in which the plants have upward growth 
 like ordinary trees, and the tissues are partly vascular : it is 
 the one containing the Ferns, Lycopodia, and Equiseta. The 
 most ancient of land plants belong, to a great extent, to 
 this order, the highest of Cryptogams. Another portion are 
 related to the lowest order of flower-bearing plants, or Pheno- 
 gams, called G-ymnosperms (see p. 61). 
 
 The groups represented under these divisions are the 
 following : 
 
 I. FLOWERLESS PLANTS, or CRYPTOGAMS, Order of ACRO- 
 
 GENS. 
 
 1. Fern tribe. The species have a general resemblance to 
 the ferns or brakes of the present time. 
 
 2. Lycopodium tribe, or that of the Ground-pine. The ex- 
 isting plants of this tribe are slender species, seldom over 4 
 or 5 feet high : some of the ancient were of the size of forest- 
 trees. These ancient species belong mostly to the Lepido- 
 dendron family, in which the scars are contiguous and are 
 arranged in quincunx order, that is, alternate in adjoining 
 rows, as shown in fig. 177. The Ground-pine of our woods, 
 although nowerless like the fern, has leaves very similar to 
 those of the spruce or cedar (Conifers) ; and this type of 
 plants is intermediate in some respects between the Aero- 
 gens and Gymnosperms (Conifers). 
 
 3. Equisetum tribe. The Equiseta of modern wet woods 
 are slender, hollow, jointed rushes, called sometimes scouring- 
 rushes. They often have a circle of slender leaf-like append- 
 ages at each joint. 
 
 The CalamiteSj or tree-rushes, are peculiar to the ancient 
 world, none having existed since the Mesozoic. They had 
 jointed striated stems like the Equiseta, and otherwise 
 resembled them. But they were often a score of feet or 
 more in height, and sometimes 6 inches in diameter. Some 
 of them had hollow stems like the Equiseta; others fead the 
 interior of the stems woody, and these were intermediate in 
 
DEVONIAN AGE. 109 
 
 some respects between the Equiseta and the Gymnosperms. 
 Fig. 225, under the Carboniferous age, represents a portion 
 of one of these plants. 
 
 II. FLOWERING PLANTS, or PHENOGAMS, of the Order of 
 GYMNOSPERMS. 
 
 1. Conifers. The species are related to the common pines 
 and spruces, or more nearly to the Araucarian pines of 
 Australia and South America. The fossils are merely por- 
 tions of the trunk or branches. It has been suggested by 
 Mr. Lesquereux that all the specimens belong to the follow- 
 ing tribe : 
 
 2. Sigillarids. The Sigillarice were trees of moderate 
 height, with stout, sparingly-branched trunks, bearing long 
 linear leaves much like those of the Lepidodendra. The 
 scars on the exterior are mostly in parallel vertical lines, as 
 in fig. 178 and fig. 222, p. 127, and not in quincunx order, 
 like those of the Lepidodendra. 
 
 The earliest fossil land-plants thus far found in the United 
 States occur in the Hamilton formation. Whether they 
 occur lower than this, or in earlier Devonian, in Canada 
 and New Brunswick, is not certain. 
 
 Conifers, Ferns, and Lepidodendra have also been reported 
 from some of the Devonian beds of Britain and Europe. The 
 earliest remains found in Great Britain occur in the lowest 
 Devonian, and also in the Upper Ludlow beds (p. 99). 
 
 The hornstone develops, under the microscope, the fact 
 that it was probably made from the siliceous remains of 
 plants and animals. Figs. 180 to 194 represent some of the 
 species which have been detected by Dr. M. C. White in 
 specimens from New York and elsewhere. Figs. 180 to 186 
 are microscopic plants, related to the Desmids; fig. 187 is 
 another kind, called a Diatom, a kind which forms siliceous 
 shells, and which is probably one of the sources of the 
 silica of which the hornstone was made. (See, on Diatoms 
 and Desmids, p. 61.) Figs. 188, 189 are spicules of Sponges, 
 
110 
 
 PALEOZOIC TIME. 
 
 also siliceous, and another of the sources of the silica. Figs. 
 190-192 are probably also sponge-spicules. Figs. 193, 194 are 
 fragments of the teeth of some Gasteropod Mollusk. The 
 last is from a hornstone of the Trenton period (Silurian) 
 which was found to afford the same evidences of organic 
 origin. 
 
 3. Animals. 
 
 The early Devonian was the coral period of the ancient 
 world. In no age before or since, not even the present, have 
 coral reefs of greater extent been formed. 
 
 Among Mollusks, Brachiopods were still the prevailing 
 kinds, though ordinary Bivalves or Conchifers, and Uni- 
 
 Figs. 180-194. 
 
 80 
 
 Microscopic Organisms from the Hornstone. 
 
 valves or Gasteropods, were more abundant than in the 
 Silurian. A new type of Cephalopods commenced in the 
 Middle Devonian. Hitherto, the partitions or septa in the 
 shells, straight or coiled, were flat or simply concave ; but 
 in the new genus Goniatites, the margin of the plate has one 
 or more deep angles, one of the angles being at the middle 
 of the back of the shell. The name is from the Greek gonu, 
 knee or angle. 
 
 Among Articulates, there were "Worms and Crustaceans 
 as in earlier time, and the most common Crustaceans were 
 Trilobites. Besides these there were the first of Insects, the 
 wings of some species having been reported from the Devo- 
 nian of New Brunswick. 
 
DEVONIAN AGE. 
 Figs. 195-200. 
 
 Ill 
 
 200 
 
 RADIATES. Fig. 195, Zaphrentia Rafinesquii; 196, 197, Cyathophyllum rngosum; 198, 
 Syringopora Maclurii; 199, Aulopora cornuta; 200, Favosites Goldfussi: all of the Cornif- 
 erous period. 
 
 1. Badiates. Fig. 195, one of the Cyathophylloid corals, 
 Zaphrentis Rafinesquii ; fig. 196, another, Cyathophyllum rugo- 
 SMTTi, both from the Falls of the Ohio, and the latter forming 
 very large masses. Fig. 197 is a top view of the cells in 
 fig. 196. Fig. 200, a Favosites from the same locality, showing 
 well the columnar structure characterizing the genus : the 
 species F. Goldfussi occurs both in America and Europe. 
 Figs. 198 and 199 are small corals from Canada West. 
 
 2. Mollusks. Figs. 201 to 203, Brachiopods from the 
 Hamilton beds; figs. 204, 205, Conchifers, from the same; 
 fig. 206, Goniatites Marcellensis, ib.; fig. 207, a view of the 
 back, showing the angles in the partitions, this species hav- 
 ing only one angle or re-entering lobe. 
 
 3. Articulates. Fig. 208, the Trilobite Phacops Bufo. 
 
 4. Vertebrates. The fishes of the Devonian belong to two 
 orders : the Ganoid and the Selachian (see p. 51). Some of 
 the Ganoids are represented in figs. 210 to 216. The fishes 
 of this order are related in several points to Eep tiles. Unlike 
 ordinary fishes (or the Teliosts) (1) they have the power 
 of moving the head up and down at the articulation between 
 
112 
 
 PALEOZOIC TIME. 
 
 the head and the body, the articulation being made by means 
 of a convex and concave surface ; (2) the air-bladder, which 
 
 Figs. 201-208. 
 
 MOLLUSKS. Fig. 201, Atrypa aspera; 202, Spirifer mucronatua ; 203, Chonetes setigera; 204, 
 Grammysia Hamiltonensis ; 205, Microdon bellistriatus ; 206, 207, Goniatites Marcellensis t 
 all from the Hamilton group. ARTICULATES : Fig. 208, Phacops Bufo, from the Hamilton 
 group. 
 
 answers to the lung of higher animals, has a cellular or 
 lung-like structure, thus approximating to air-breathing 
 species ; (3) the teeth have in general a structure like that 
 of some early Reptiles. Fig. 210 is a reduced view of a Ganoid 
 with large plates over the body, like a Turtle : moreover, it 
 moved by means of paddles instead of its tail, the principal 
 organ of motion in most Fishes, and in this, also, it resembles 
 
DEVONIAN AGE. 
 
 113 
 
 Turtles. It is the Pterichthys of Agassiz, a name signifying 
 winged fish. There is another plate-covered kind, one genus 
 
 Figs. 209, 210. 
 
 VERTEBRATES. Fig. 209, Fin-spine of a Shark (X %); 210, Pterichthys Milleri (X%). 
 
 of which is named Coccosteus, which wants the paddles, and 
 sculled itself along with the tail, like most Fishes. Fig. 211 
 represents a different type of Ganoid, the Cephalaspis, having 
 a flat and broad plate-covered head, with rhombic scales 
 over the body : figs. 212 show the forms of some of the 
 scales. Fig. 215 is another, a species of Dipterus, covered 
 with rhombic scales, put on, as in the preceding, much as 
 tiles are arranged on a roof: fig. 216 is one of the scales, 
 natural size. Fig. 213 is another type of Ganoids, having 
 the scales rounded and set on more like shingles ; it is a Holo- 
 ptycliius : fig. 214 represents a scale, natural size. These figures 
 are all much reduced. Scales of & Holoptychius have been found 
 in Chemung beds which were over an inch and a half broad, 
 indicating the existence of fishes of great size. 
 
114 
 
 PALEOZOIC TIME. 
 
 The Selachians, or species of the shark tribe, belong to the 
 family of Cestracionts (p. 52), or that in which the mouth 
 
 Figs. 211-216. 
 11 
 
 GANOIDS. Fig. 211, Cephalaspis Lyellii (X%); 212, Scales; 213, Holoptychius (XH); 214, 
 Scale ; 215, Dipterus macrolepidotus (X K) 5 216 > Scale. 
 
 has a pavement of broad bony pieces for grinding. The 
 food in the seas for these carnivorous Fishes consisted mainly 
 of shell-fish and mail-clad Ganoids; and grinders were, there- 
 fore, better suited for the times than cutting teeth. Many 
 of these Cestraciont sharks were of very large size. Fig. 
 209 represents a fin-spine of one, drawn two-thirds its actual 
 size, found in the Corniferous beds of the State of New York. 
 
DEVONIAN AGE. 115 
 
 The remains of Fishes in the rocks are numerous after the 
 first appearance of them. 
 
 4. General Observations, 
 
 1. Geography. During the Silurian there had heen a gra- 
 dual gain of dry land on the north, extending the Azoic con- 
 tinent (p. 73) southward. This gain continued through the 
 Devonian, so that the beds of the next age, the Carbon- 
 iferous, extend only a short distance north of the southern 
 boundary of New York. The sea-shore was thus being set 
 farther and farther southward with the progressing periods. 
 
 The formations have their greatest thickness along the 
 Appalachian region, as in the Silurian Age. And both this 
 fact and their successions lead to similar general conclu- 
 sions to those stated 011 page 102. 
 
 2. Life. The great feature of the Devonian age is the 
 introduction of the first of terrestrial plants, the first of ter- 
 restrial animals (Insects), and the first of Yertebrates. It 
 is possible that future discovery may throw farther back in 
 time the commencement of these types. However this may 
 be, whenever the first land-plant appeared, it was an epoch 
 of great progress in the system of life on the earth. It was 
 a change from the leafless Sea-weed to Ferns, Lepidodeiidra, 
 and Pines, from a bare and lifeless world above tide-level 
 to one of forest-clad hills. 
 
 This step of progress from Sea-weeds to Ferns, Lycopo- 
 dia, and Pines was not made by a gradual working upward 
 through Mosses arid other low forms of Cryptogams. On 
 the contrary, no Mosses, although many are true marsh- 
 species, appear to have been in existence until long after the 
 close of the Carboniferous age. It was a sudden advance 
 from the lowest to the highest of Cryptogams. 
 
 In the same manner, with regard to Fishes, the earliest 
 species belong to the two highest groups of the class, the 
 Sharks and Ganoids; and both are above the level of the 
 
 11 
 
116 PALEOZOIC TIME. 
 
 fish, the Ganoids being partly Reptilian. There is not the 
 least evidence of any development upward from the Mollusk, 
 Worm, or Trilobite to these Fishes, or of a gradual rise in 
 the grade of Fishes from the lower to the highest. The 
 Devonian Fishes are often of great size and eminently com- 
 plete and perfect in their parts. Their introduction into 
 the system of life was a no less sudden step upward than 
 in the case of plants. 
 
 There are here no facts sustaining the theory that species 
 were made from species by a natural process of growth or 
 development. Without any known natural method of crea- 
 tion to appeal to, Science is led rightly to ascribe the exist- 
 ence of plants and smimals, each in its time and place, to 
 Him alone who created " in the beginning." 
 
 HI. CARBONIFEROUS AGE, OR AGE OF COAL 
 PLANTS. 
 
 1, General Characteristics: Subdivision. 
 
 The Carboniferous age was remarkable, in general, for 
 
 (1.) The wide limits of the continents above the sea-level. 
 
 (2.) The extent of the low marshy or fresh- water areas 
 over these continents, and the flat or gently undulating 
 surface of nearly all the rest of the emerged land, few ele- 
 vated ridges existing any where. 
 
 (3.) The luxuriant vegetation, clothing the land with 
 forests and jungles. 
 
 (4.) The existence of Insect life over the land, and of 
 Amphibians and other Reptiles in the marshes and seas. 
 
 But, while having these as its main characteristics, it was 
 not an age of continued verdure. There was, first, a long 
 periocU-^the Subcarboniferous-^m which the land was mostly 
 beneath the sea; for limestone, full of marine fossils, is the 
 
CARBONIFEROUS AGE. 117 
 
 prevailing rock, and there are but thin coal seams in some 
 regions of sandstones and shales. This period was followed 
 by the Carboniferous, or that of the true Coal measures. Yet 
 even in this middle period of the age there were alterna- 
 tions of submerged with emerged continents, long eras of 
 dry and marshy lands luxuriantly overgrown with shrub- 
 bery and forest-trees intervening between other long eras 
 of great barren continental seas. Then there was a closing 
 period, the Permian m which the ocean prevailed again, 
 though with contracted limits ; for the rocks are mainly of 
 marine origin. 
 
 The Carboniferous period and age were so named from the 
 fact that the great coal beds of the world originated mainly 
 during their progress. The term Permian was given to the 
 rocks of the third period by Murchison, de Yerneuil and 
 Keyserling, from a region of Permian rocks in Eussia, the 
 ancient kingdom of Permia, now divided into the govern- 
 ments of Perm, Yiatka, Kasan, Orenberg, etc. 
 
 2. Distribution of Carboniferous Hocks. 
 
 The Carboniferous areas on the map of the United States, 
 p. 69, are the dark areas; the black cross-lined with white 
 being the Subcarboniferous; the pure black, the Carbonife- 
 rous ; the black dotted with white, the Permian. The last 
 occur only west of the Mississippi. 
 
 The following are the positions of the several great areas 
 in North America : 
 
 I. EASTERN BORDER REGION. (1.) The Rhode Island area, 
 extending from Newport in Rhode Island to Worcester in 
 Massachusetts. 
 
 (2.) The Nova Scotia and New Brunswick area. 
 
 II. APPALACHIAN and INTERIOR REGIONS. (1.) The great 
 Appalachian area, extending from the southern borders of 
 New York and Ohio southwestward to Alabama, covering 
 the larger part of Pennsylvania, half of Ohio, part of 
 
118 
 
 PALEOZOIC TIME. 
 
 Kentucky and Tennessee, and a little of Mississippi. To 
 the northeast, in Pennsylvania, this coal field is much 
 broken into patches, as shown in the accompanying map of 
 
 a part of the State, the black areas being those of the coal 
 district. 
 
 (2.) The Michigan area, covering the central part of the 
 State. 
 
CARBONIFEROUS AGE. 119 
 
 (3.) The Illinois and Missouri area, or that of the Missis- 
 sippi basin, covering much of Illinois, and part of Indiana, 
 Kentucky, Iowa, Minnesota, Missouri, Kansas, and Arkansas, 
 and stretching southward into northern Texas. 
 
 (4.) The Rocky Mountain area, situated in some parts of the 
 summits of the Kocky Mountains, as around the Great Salt 
 Lake in Utah. 
 
 III. ARCTIC EEGION. The Melville Island, and those of 
 other islands between Grinnell Land and Banks Land, 
 mostly north of latitude 70. 
 
 The areas of workable coal measures are estimated as 
 follow : 
 
 1. Rhode Island 1,000 square miles. 
 
 2. Nova Scotia and New Brunswick 18,000 " " 
 
 3. Appalachian 60,000 " " 
 
 4. Michigan 5,000 " " 
 
 5. Illinois and Missouri 60,000 " " 
 
 The total for the whole United States is about 130,000 
 
 square miles. 
 
 Carboniferous strata occur also in Great Britain and 
 various parts of Europe. Those of England are distributed 
 over an area between South Wales on the west and the 
 Newcastle basin on the northeast coast (as shown by the 
 black areas on the following map), the most important for 
 coal being the South Wales region ; the Lancashire district, 
 bordering on Manchester and Liverpool; the Yorkshire, 
 about Leeds and Sheffield ; and the Newcastle. 
 
 Scotland has some small areas between the Grampian 
 range on the north and the Lammermuirs on the south ; and 
 Ireland, several coal regions of large extent, as at Ulster, 
 Connaught, Leinster (Kilkenny), and Munster. 
 
 The coal-fields of Europe which are most worked are the 
 Belgian, bordering on and passing into France. Germany 
 contains only small coal-bearing areas; and Russia in Europe 
 
 11* 
 
120 
 
 PALEOZOIC TIME. 
 Fig. 218. 
 
 Fig. 218, Geological Map of England. The areas lined horizontally and numbered 1 are 
 Silurian. Those lined vertically (2), Devonian. Those cross-lined (3), Subcarboniferous. 
 Carboniferous (4), black. Permian (5). Those lined obliquely from right to left, Triassic (6), 
 Lias (7 a), Oolite (7 fc), Wealden (8), Cretaceous (9). Those lined obliquely from left to 
 right (10, 11), Tertiary. A is London, B, Liverpool, C, Manchester, D, Newcastle. 
 
CARBONIFEROUS AGE. 121 
 
 almost none, although the Subcarboniferous and Permian 
 rocks cover large portions of the surface. 
 
 The following are the areas of some of the foreign coal 
 districts : 
 
 Great Britain and Ireland 12,000 square miles. 
 
 Spain 4,000 " " 
 
 France 2,000? " " 
 
 Belgium 518 " " 
 
 or less than 20,000 square miles, against 148,000 in North 
 America. 
 
 Valuable coal beds are not found in any rocks older than 
 the Carboniferous, although black bituminous slates are not 
 uncommon even in the Lower Silurian. They occur, how- 
 ever, in different Mesozoic formations, and also occasionally 
 in the Cenozoic, but not of the extent which they have in 
 the Carboniferous formations. 
 
 3. Kinds of Rocks. 
 
 1. SUBCARBONIFEROUS PERIOD. The Subcarboniferous 
 strata in the Interior Continental region are mainly lime- 
 stone; and, as the limestone abounds in many places in Cri- 
 noidal remains, the rock is often called the Crinoidal limestone. 
 In the Appalachian region, in middle and southern Virginia, 
 the rock is also limestone, and has great thickness; but in 
 northern Virginia and Pennsylvania it is mostly a sandstone 
 or conglomerate overlaid by a shaly or clayey sandstone and 
 marlite of reddish and other colors, the whole having a 
 maximum thickness of 5000 to 6000 feet. In the Eastern 
 border region, in Nova Scotia, the rocks are mostly reddish 
 sandstone and marlite, with some limestone, the estimated 
 thickness 6000 feet. 
 
 The prevailing rock in Great Britain and Europe is a 
 limestone, called there the Mountain limestone. 
 
 2. CARBONIFEROUS PERIOD. (1.) Hocks of the Coal forma- 
 tion. The rocks of the Carboniferous period that is, those 
 
122 PALEOZOIC TIME. 
 
 of the Coal measures are sandstones, shales, conglomerates, 
 and occasionally limestones ; and they are so similar to the 
 rocks of the Devonian and Silurian ages that they cannot 
 be distinguished except by the fossils. They occur in various 
 alternations, with an occasional bed of coal between them. 
 The coal-beds, taken together, make up not more than one- 
 fiftieth of the whole thickness ; that is, there are 50 feet or 
 more of barren rock in the coal formation to 1 foot of coal. 
 An example of the alternations is given in the following 
 section : 
 
 1. Sandstone and conglomerate beds 120 feet. 
 
 2. COAL 6 " 
 
 3. Fine-grained shaly sandstone 50 " 
 
 4. Siliceous iron-ore 1 " 
 
 5. Argillaceous sandstone 75 " 
 
 6. COAL, upper 4 feet shale, with fossil plants, and below a thin 
 
 clayey layer 7 " 
 
 7. Sandstone 80 " 
 
 8. Iron-Ore 1 " 
 
 9. Argillaceous shale 80 " 
 
 10. LIMESTONE (oolitic), containing Producti, Grinoids, etc 11 " 
 
 11. Iron- Ore, with many fossil shells 3 " 
 
 12. Coarse sandstone, containing trunks of trees 25 " 
 
 13. COAL, lying on 1 foot slaty shale with fossil plants 5 " 
 
 14. Coarse sandstone 12 " 
 
 The limestone strata are more numerous and extensive 
 in the Interior Continental region than in the Appalachian, 
 and west of the States of Missouri and Kansas limestone is 
 the prevailing rock. 
 
 Beds of argillaceous iron-ore are very common in coal 
 districts, so that the same region affords ore and the coal 
 for smelting it. Some of the largest iron-works in the world, 
 on both sides of the Atlantic, occur in coal districts. 
 
 The coal beds often rest on a bed of grayish or bluish clay, 
 called the under-day, which is filled with the roots or stems 
 of plants. When this under-clay is absent, the rock is 
 usually a sandstone or shale. Above the coal, the rock may 
 
CARBONIFEROUS AGE. 
 
 123 
 
 be sandstone, shale, conglomerate, or even limestone; often 
 the layer next above, especially if shaly, is filled with fossil 
 leaves and stems. In some cases, trunks of old trees rise 
 from the coal and extend up through overlying beds, as in 
 the annexed figure, by Dawson, from the Nova Scotia Coal 
 measures. Occasionally, as in Ohio, logs 50 to 60 feet long 
 lie scattered through the sandstone beds, looking as if a 
 forest had been swept off from the land into the sea. 
 
 (2.) Coal beds. The coal beds vary in thickness from a 
 fraction of an inch to 30 or 40 feet, but seldom exceed 8 feet, 
 
 Fig. 219. 
 
 
 
 Section of a portion of the Coal measures at the Joggins, Nova Scotia, having erect stumps, 
 and also " rootlets" in the under-clays. 
 
 and are generally much thinner : 8 feet is the thickness of 
 the principal bed at Pittsburg, Pa.; 29 feet, that of the 
 " Mammoth Vein" at Wilkesbarre, Pa. ; 37 feet, that of one 
 of the two great beds at Pictou in Nova Scotia. In these 
 thick beds, and often also in the thin ones, there are some 
 intervening beds of shale, or of very impure coal, so that 
 the whole is not fit for burning. 
 
 The coal varies in kind according to the proportion of 
 bituminous substances present, that containing little or 
 none being called Anthracite, and the rest Bituminous coal 
 (see p. 18). When only 10 or 15 per cent, of bituminous 
 substances are present, it is often called Semi-bituminous coal. 
 In Pennsylvania the coal of the Pottsville, Lehigh, and 
 Wilkesbarre regions is anthracite; that of Pit^burg, bitumi- 
 
124 PALEOZOIC TIME. 
 
 nous coal; and that of part of the intermediate district, 
 semi-bituminous, as so designated on the map, page 118. 
 
 The coal also varies as to the impurities present. All of 
 it contains more or less of earthy material, as clay or silica ; 
 and this earthy material constitutes the ashes and slag of a 
 coal fire. Ordinary good anthracite contains 7 to 12 pounds 
 of impurities in a hundred pounds of coal. In some coal 
 beds there is considerable pyrites or sulphuret of iron (a 
 compound of sulphur and iron), and the coal is then unfit 
 for use. It is seldom that pyrites is altogether absent. The 
 sulphur gases which are perceived in the smoke or gas from 
 a coal fire come usually from the decomposition of pyrites. 
 
 Mineral coal, although it seldom breaks into plates unless 
 quite impure, still consists of thin layers. This is shown in 
 the hardest anthracite by a delicate banding of a surface of 
 fracture, as may be readily seen when it is held up to the 
 light. This structure is absent in the variety called Cannel 
 coal, which is a bituminous coal, very compact in texture, 
 feeble in lustre, and smooth and often flint-like in fracture. 
 
 (3.) Mineral Oil. Besides mineral coal, the rocks some- 
 times afford bituminous liquids, called ordinarily petroleum, 
 or mineral oil, or, when purified for burning, kerosene, and 
 sometimes mineral naphtha. Oil-wells are largely worked at 
 Titusville in Pennsylvania, and at Mecca in Trumbull co., 
 Ohio ; and it is probable that the material at each of these 
 places proceeds from the lower Subcarboniferous rocks, 
 though possibly from the Devonian. Petroleum is a result 
 of the decomposition of vegetable substances. It proceeds 
 from rocks of various ages, from those of the Lower Silu- 
 rian to the Tertiary. The earliest springs affording a large 
 supply of oil come from the Corniferous beds (Devonian), 
 as at Enniskillen in Canada. 
 
 (4.) Salt or Salines. The Subcarboniferous formation in 
 Michigan, at Grand Rapids and the adjoining region, affords 
 extensive salines, and there are many wells opened by 
 
CARBONIFEROUS AGE. 125 
 
 boring. The beds affording the saline waters consist of 
 clayey beds or marlites, shale, and magnesian limestone, and 
 abound also in gypsum, thus resembling those of the Salina 
 period in New York (p. 95). 
 
 3. PERMIAN PERIOD. The rocks of the Permian beds are 
 mostly sandstones and marlites, with some impure or mag- 
 nesian limestones, and gypsum. They occur in North Ame- 
 rica west of the Mississippi in Kansas, and about some parts 
 of the eastern slope of the Eocky Mountains, where they lie 
 conformably over the Carboniferous. Similar rocks occur in 
 Great Britain in the vicinity of several of the coal regions, 
 and also in Germany and Russia. Thin seams of coal are 
 occasionally interstratrfied with the sandstones, but none of 
 workable extent are known. 
 
 4. Life. 
 1. Plants. 
 
 The plants of the forests, jungles, and floating islands of 
 the Carboniferous Age, thus far made known, number about 
 900 species. Among the fossils there are none that afford 
 satisfactory evidence of the presence of either Angiosperms 
 or Palms (p. 62) ; for no net-veined leaves, allied in charac- 
 ter to those of the Oak, Maple, Willow, Eose, etc., have been 
 found among them ; and no palm-leaves or palm-wood. More- 
 over, the plains were without grass, and the swamps and 
 woods without moss. At the present day Angiosperms, 
 along with Conifers, or the Pine family, make up the great 
 bulk of our shrubs and forest-vegetation; Palms abound 
 in all tropical countries; grass covers all exposed slopes 
 where the climate is not too arid ; and mosses are the prin- 
 cipal vegetation of most open marshes. 
 
 The view in fig. 220 gives some idea of the Carbon- 
 iferous vegetation over the plains and marshes of the era. 
 
 The Carboniferous species, like their predecessors in the 
 Devonian age, belonged to the following groups : 
 
12G 
 
 PALEOZOIC TIME. 
 
 I. CRYPTOGAMS, or Flowerless Plants, Order of ACROGENS. 
 
 (1.) Fern tribe. Ferns were very abundant, a large part of 
 
 the fossil plants of a coal region being their delicate fronds 
 
 Fig. 220. 
 
 Carboniferous Vegetation. 
 
 (usually called leaves). One of them is represented in fig. 
 224. Besides small species, like the common kinds of the 
 present day, there 'were tree-ferns, species that had a trunk, 
 perhaps 15 or 20 feet high, and which bore at top a radiating 
 tuft of the very large leaf-like fronds, resembling the 
 
CARBONIFEROUS AGE. 
 
 127 
 
 modern tree-fern of the tropics. One of the tree-ferns of the 
 Pacific is represented in fig. 220, near the middle of the view, 
 and smaller ferns in front of it below. Tree-ferns, however, 
 
 Figs. 221-226. 
 
 Fig. 221, Lepidodendron obovatum; 222, Sigillaria oculata; 223, Stigmaria ficoides; 224, 
 Sphenopteris Gravenborstii; 225, Calamitea cannseformis ; 226, Trigonocarpum tricuspi- 
 datum. 
 
 were not common in the Carboniferous forests. The scars 
 in fossil or recent tree-ferns are many times larger than 
 
 12 
 
 [ , - V : 
 
128 PALEOZOIC TIME. 
 
 those of Lepidodendra, and the fossils may be thus distin- 
 guished. 
 
 (2.) Lycopodium tribe. The Lepidodendra appear to have 
 been among the most abundant of Carboniferous forest- 
 trees, especially in the earlier half of the Carboniferous 
 Age, or to the middle of the Coal Period. They probably 
 covered both the marshes and the drier plains and hills. 
 Some of the old logs now preserved in the strata are 50 to 
 60 feet in length; and the pine-like leaves were occasionally 
 a foot or more long. The taller tree to the left, in figure 
 220, is a Lepidodendron. Figure 221 shows the surface- 
 markings of one of the species, natural size : the regular 
 arrangement of the scars resembles a little the arrangement 
 of scales on a fish, and this gave origin to the name Lepido- 
 dendron, from the Greek lepis, scale, and dendron, tree. 
 
 (3.) Equisetum tribe. Fig. 225 represents a portion of one 
 of the tree-rushes, or Calamites, usually regarded as of the 
 Equisetum tribe. The species were evidently very abundant 
 in the great marshes, through the whole of the Carbonif- 
 erous Age ; some were 20 feet or more high, and 10 or 12 
 inches in diameter. 
 
 Besides these Cryptogams there were also Funcji, or Musli- 
 gpoms; but, as already stated, no remains of Mosses from ' A ie 
 rocks of the age are known./ 
 
 II. PHENOGAMS, or Flowering Plants, Order of GYMNO- 
 
 SPERMS. 
 
 (1.) Conifers. Trunks of trees, supposed to be Coniferous 
 in character, and related especially to the Araucarian pines, 
 are common. As stated on p. 109, they may be the trunks 
 of Sigillarids ; yet this is not probable. 
 
 (2.) Sigillarids. The Sigillarice were a very marked fea- 
 ture of the great jungles and damp forests of the Coal period. 
 They grew to a height sometimes of 30 to 60 feet ; but the 
 trunks were seldom branched, and must have had a stiff, 
 clumsy aspect, although covered above with long, si der, 
 
CARBONIFEROUS AGE. 129 
 
 rush-like leaves. Fig. 222 represents a common species, 
 exhibiting the usual arrangement of the scars, in vertical 
 lines, and also indicating, by the difference in the scars of 
 the right row from those of the others, the difference of 
 form on the inside and outside of the bark. 
 
 (3.) Stigmarice. The fossil jStigmarice are stout stems, 
 generally 2 to 3 or more inches thick, having over the sur- 
 face distant rounded punctures or depressions. 
 
 Fig. 223 is a portion of the extremity of a stem, showing 
 the rounded depressions and also the leaf-like appendages 
 occasionally observed. The stems or branches are a little 
 irregular in form, and sparingly branched. They have been 
 found spreading, like roots, from the base of the trunk of a 
 Sigillaria, and sometimes also from that of a Lepidodendron ; 
 and they are hence regarded either as the roots or sub- 
 aqueous stems of these trees. They are an exceedingly 
 common fossil, especially in the under-clays of the Coal 
 measures (p. 122). If they are roots, they indicate that the 
 under-clay, as stated by Logan, was the old dirt-bed in which 
 the vegetation that gave rise to a bed of coal first took root. 
 If subaqueous stems, as Lesquereux believes them to have 
 often been, they grew and spread through the shallow 
 waters, and formed the basis of floating vegetation, while 
 tne clay was accumulating over the bottom, like the fire- 
 clay beneath a modern peat-bed. 
 
 In the Carboniferous landscape, fig. 220, p. 126, the broken 
 trunk to the right is a Sigillaria. The landscape, to be quite 
 true to nature, should have been made up largely of Sigil- 
 larice, Catamites, and Lepidodendra, with few tree-ferns. The 
 Stigmaria3 would have been mostly concealed beneath tho 
 water or soil, or in the submerged mass of the floating islands. 
 
 (4.) Fruits. Besides the leaves, stems, and trunks already 
 alluded to, there are various nut-like fruits found in the 
 Carboniferous strata. One is represented in fig. 226, the 
 fig^ 3 to the left being that of the shell, and the other that 
 
130 PALEOZOIC TIME. 
 
 of the nut which it contained. Some of them are two inches 
 in length. The most of them were probably the fruit of 
 Sigillarice or Conifers ; some, perhaps, of the Lepidodendra. 
 
 (5.) Conclusions. It is seen from the above that 
 
 (1.) The vegetation of the Carboniferous age consisted 
 very largely of Cryptogams, or flowerless plants. 
 
 (2.) The flowering plants, or Phenogams, associated with 
 the flowerless vegetation, were of the order of Gymno- 
 sperms, whose flowers are incomplete and inconspicuous. 
 
 (3.) While, therefore, there was abundant and beautiful 
 foliage (for no foliage exceeds in beauty that of Ferns), the 
 vegetation was nearly flowerless. 
 
 (4.) The characteristic Cryptogams were not only of the 
 highest group of that division of plants, but in general they 
 exceeded in size and perfection the species of the present 
 day, many being forest-trees. 
 
 2. Animals. 
 
 The principal steps of progress in animal life have already 
 been in part pointed out, viz. the increase in the variety 
 and number of land- Articulates ; there being Myriapods (or 
 Centipedes) and Scorpions, as well as Insects; and the rise in 
 Vertebrates from water-Vertebrates, or Fishes, to Reptiles. 
 
 1. Radiates. Among Radiates, species of Crinoids were 
 especially numerous and varied in form in the Subcarbonif- 
 erous period. Figs. 227 to 229 represent some of the species. 
 The radiating arms are perfect in fig. 227, but wanting in 228. 
 Fig. 229 is a species of the genus Pentremites (named from the 
 Greek pente, five, alluding to the five-sided form of the fossil). 
 The Pentremites had a long stem made of calcareous disks, 
 like other Crinoids, but no long radiating arms at top. 
 
 Fig. 230 presents an upper view of a very common Coral 
 of the same period : it has a columnar appearance in a side 
 view. 
 
 2. Mollusks. The tribe of Bryozoans contained the sin- 
 
CARBONIFEROUS AGE. 
 
 131 
 
 gular screw-shaped (or auger-shaped) coral shown in fig. 231, 
 and named Archimedes (referring to Archimedes' screw). It 
 
 27 
 
 Figs. 227-237. 
 
 31 
 
 RADIATES : Fig. 227, Zeacrinus elegans ; 228, Actinocrinus proboscidialis ; 229, Pentremites 
 pyriformis ; 230, Lithostrotion Canadense. MOLLUSKS : Fig. 231, Archimedes reversa ; 232, 
 Chonetes mesoloba; 233, Productus Rogersi; 234, Spirifer cameratus; 235, Athyris sub- 
 tilita ; 236, Pleurotomaria tabulata ; 237, Pupa vetusta. 
 
 is made up of minute cells that open over the lower surface; 
 each of the cells, when alive, contained a minute Bryozoan 
 
 12* 
 
132 
 
 PALEOZOIC TIME. 
 
 (p. 57). These fossils are common in some of the Subcar- 
 boniferous limestone strata. 
 
 Brachiopods were the most abundant of Mollusks through 
 the Carboniferous age, and especially species of the genera 
 Spirifer and Productus. Figures 232 to 235 are of species 
 from the American Coal measures: fig. 234, a Spirifer; fig. 
 233, a Productus; fig. 232, a Chonetes; fig. 235, an Athyris, 
 occuring also in Europe. Fig. 236 represents one of the 
 Gasteropods of the Coal measures. Fig. 237 is a Pupa, the 
 first yet known of land-snails : it is from the Coal measures 
 of Nova Scotia. The order of Cephalopods contained but 
 few and small species of the old tribe of Orthocerata, but 
 many of the Ammonite-like Goniatites. 
 
 3. Articulates. Among Articulates, Crustaceans appeared 
 under a new form, much like that of modern shrimps (fig. 
 238, from Scotland), and Trilobites were of rare occurrence. 
 
 Figs. 238-240. 
 
 CRUSTACEAN : Fig. 238, Anthracopalaemon Salteri. MYRIAPOD : Fig. 239 a, Xylobius Sigil- 
 larise. INSECT-WING : Fig. 240, Blattina venusta. 
 
 Fig. 239 represents a Myriapod resembling a modern 
 lulus, from Nova Scotia ; 239 a, shows the organs of the 
 mouth, as they are still preserved in the specimen. 
 
 Fig. 240 is a wing of an Insect of the genus Blattina, 
 
CARBONIFEROUS AGE. 
 
 133 
 
 related to the modern Cockroach (or Blatta}, drawn from a 
 specimen obtained in the Coal measures of Arkansas. There 
 were also species of Neuropterous insects, of Locusts (or 
 Orthopterous insects) and Beetles (or Coleopters), besides 
 Scorpions (of the class of Spiders). 
 
 4. Vertebrates. Fishes were numerous, both of the orders 
 of Ganoids and Selachians. All the Ganoids were of the 
 ancient type, having the caudal fin vertebrated (or hetero- 
 cercal), as in the Palceoniscus, represented in fig. 241, a Per- 
 mian species. Many of the Selachians, or Sharks, were of 
 great size, as shown by the fin-spines. Fig. 242 represents 
 a small portion of one of these spines, natural size, from 
 the Subcarboniferous beds of Europe. One of the largest 
 specimens of the same species thus far found had a length 
 
 Figs. 241, 242. 
 
 Fig. 241, Paleeoniscus Freieslebeni (X %); 242, Part of a spine of Ctenacanthus major. 
 
 of 14J inches, and when entire it must have been full 18 
 inches long. 
 
134 
 
 PALEOZOIC TIME. 
 
 The first traces of Reptiles yet known occur in the Sub- 
 carboniferous beds of Pottsville, Pennsylvania. 
 
 Figs. 243-245. 
 
 Fig. 243, Tracks of Sauropus primsevus (XH); 2 4, Raniceps Lyellii ; 245 a, Vertebra of 
 Eosaunis Acadianui. 
 
CARBONIFEROUS AGE. + 135 
 
 Fig. 243 is a reduced sketch of a slab containing tracks 
 of the species, and also an impression left by the tail of the 
 animal. The tracks of the fore-feet, as described by I. Lea, 
 are 5-fingered and 4 inches broad, and those of the hind 
 feet 4-fingered and nearly of the same size; while the stride 
 indicated was 13 inches. Fig. 244 represents a skeleton of 
 an Amphibian from the Ohio Coal measures, found by New- 
 berry; and fig. 245 a vertebra of a swimming Saurian 
 probably related to the Enaliosaurs, or Sea-Saurians, of the 
 Mesozoic (see p. 180), discovered by Marsh in the Coal 
 measures of Nova Scotia. This vertebra is concave on both 
 surfaces, as shown in the section in fig. 245 a, and in this 
 respect resembles those of fishes. The Enaliosaurs had 
 paddles like Whales. 
 
 These Enaliosaurs, or swimming Reptiles, are the highest 
 species of animal yet discovered in rocks of the Carbonif- 
 erous period. In the Permian period there were still higher 
 Reptiles, called Thecodonts (because the teeth are set in 
 sockets, from the Greek theca, case, and odous, tooth'). But 
 these also had the fish-like characteristic of doubly-concave 
 vertebrae. 
 
 5. General Observations. 
 
 1. Formation of Coal and the Coal measures. (1.) Origin of 
 the Coal. The vegetable origin of coal is proved by the fol- 
 lowing facts : 
 
 (1.) Trunks of trees, retaining still the original form and 
 part of the structure of the wood, have been found changed 
 to mineral coal, both in the Carboniferous and more modern 
 formations, showing that the change may and does take 
 place. 
 
 (2.) Beds of peat, a result of vegetable growth and accu- 
 mulation, exist in modern marshes; and in some cases they 
 are altered below to an imperfect coal (see page 263 on the 
 formation of peat). 
 
136 
 
 PALEOZOIC TIME. 
 
 (3.) Eemains of plants, their leaves, branches, and stems 
 or trunks, abound in the Coal measures ; trunks sometimes 
 extend upward from a coal-bed into and through some of 
 the overlying beds of rock ; roots or stems abound in the 
 under-clays. 
 
 (4.) The hardest anthracite contains throughout its mass 
 vegetable tissues. Prof. Bailey examined with a high mag- 
 nifying power several pieces of anthracite burnt at one end, 
 like fig. 246, taking fragments from the junction of the 
 white and black portion, and detected readily the tissues. 
 Figure 247 represents the ducts, as they appeared in one 
 case under his microscope ; and fig. 248 part of the same, 
 more magnified. 
 
 (2.) Decomposition of Vegetable Material. Carbon, the essen- 
 tial element of mineral coal, exists as one of the constituents 
 of all wood or vegetable material, making up 49 per cent, 
 (or nearly one-half) of dry wood ; and to obtain this carbon 
 as coal it is necessary only to expel the other constituents 
 
 Figs. 246-248. 
 
 of the wood, that is, the gases oxygen and hydrogen. Vege- 
 table matter decomposing in the open air like wood burnt 
 in an open fire passes, carbon and all, into gaseous combi- 
 nations, and little or no carbon is left behind. But when it 
 is decomposed slowly tinder water, or by a slow, half- 
 smothered fire, only part of the carbon is lost in gaseous 
 
CARBONIFEROUS AGE. 137 
 
 combinations, the rest remaining a& coal, called mineral 
 coal in the former case, and charcoal in the latter. 
 
 The actual loss, by weight, in the transformation into 
 bituminous coal, is at least three-fourths of the wood, and in 
 that into anthracite, five-sixths. Adding to this loss that 
 from compression, by which the material is brought to the 
 density of mineral coal, the whole reduction in bulk is not 
 less than seven-eighths for the former, and eleven-twelfths for 
 the latter. In other words, it would take 8 feet of vegetable 
 matters to make 1 of bituminous coal, and 12 feet to make 
 1 of anthracite. 
 
 (3.) Impurities in Coal. The coal thus formed contains 
 the silica existing in minute quantities in vegetable sub- 
 stances, and also other earthy materials that are not carried 
 away in solutions. By this means, and through the addition 
 of clay or earth, introduced by waters or by the winds, the 
 coal has derived the earthy impurities which give rise to the 
 ashes and slag formed in a hot fire. 
 
 (4.) Accumulation and Formation of Coal-beds. The origin 
 of coal-beds was, then, as follows : The plants of the great 
 marshes and shallow lakes of the Coal era, the latter with 
 their floating islands of vegetation, continued growing for a 
 long period, dropping annually their leaves, and from time 
 to time decaying stems or branches, until a thick accu.mula- 
 tion of vegetable remains was formed, probably 8 feet in 
 thickness for a one-foot bed of bituminous coal, or over 60 
 feet for such a bed as that of the Pittsburg region (p. 123). 
 The bed of material thus prepared over the vast wet areas 
 of the continent early commenced to undergo at bottom 
 that slow decomposition the final result of which is mineral 
 coal. But, as the coal-beds alternate with sandstones, shales, 
 conglomerates, and limestones, the long period of verdure 
 w^as followed by another of overflowing waters, and gene- 
 rally oceanic waters, as the fossifis prove, which carried 
 sands, pebbles, or earth over the old marsh, till scores or 
 
138 PALEOZOIC TIME. 
 
 hundreds ol feet in depth of such deposits had been made. 
 Thus, the bed of vegetable debris was buried where the 
 process of decomposition proper for making coal could still 
 go on to its completion ; for it would have the smothering 
 influence of the burial, as well as the presence of water, to 
 favor the process. 
 
 (5.) Climate of the Age. The wide distribution of the coal 
 regions over the globe, from the tropics to the remote 
 Arctic, and the general similarity of the vegetable remains 
 in the coal-beds of these remote zones, prove that there was 
 a general uniformity of climate over the globe in the Car- 
 boniferous age, or at least that the climate was nowhere 
 colder than warm-temperate. Similar corals and shells ex- 
 isted during the Subcarboniferous period in Europe, the 
 United States, and the Arctic within 20 of the north pole, 
 and so profusely as to form thick limestones out of their 
 accumulations. The ocean's waters, even in the Arctic, 
 were, therefore, warm compared with those of the modern 
 temperate zone, and probably quite as warm as the coral- 
 reef seas of the present age, w^hich lie mostly between the 
 parallels of 28 either side of the equator. 
 
 (6.) Atmosphere. The atmosphere was especially adapted 
 for the age in other respects. It contained a larger amount 
 than now of carbonic acid gas, the gas which promotes (if 
 not in excess) the growth of vegetation. Plants derive 
 their carbon mainly from the carbonic acid of the atmo- 
 sphere ; and hence the mineral coal of the world is approxi- 
 mately a measure of the amount of carbonic acid the atmo- 
 sphere in the Carboniferous era lost. The growth of the flora 
 of that age was a means of purifying the atmosphere so as 
 to fit it for the higher terrestrial life that was afterwards to 
 possess the world. 
 
 Again, the atmosphere was more moist than now. This 
 follows from the greater heat of the climate and the 
 greater extent as well as higher temperature of the oceans. 
 
CARBONIFEROUS AGE. 139 
 
 The continents, although large during the intervals of ver- 
 dure compared with the areas above the ocean in the Devo- 
 nian or Silurian, were still small and the land low. It must, 
 therefore, have been an era of prevailing clouds and mists. 
 A moist climate would not, however, have been universal, 
 as even the ocean has now its great areas of drought 
 depending on the courses of the. winds. America is now 
 the moist forest-continent of the globe; and the great 
 extent of the coal-fields of its northern half proves that it 
 bore the same character in the Carboniferous age. 
 
 2. Geography. (1.) Appalachian and Rocky Mountains not 
 made. On page 116 it is stated that the continents in this 
 age were low, with few mountains. The non-existence of 
 the Appalachians of Pennsylvania and Virginia is proved 
 by the fact that the rocks of these mountains are to a con- 
 siderable extent Carboniferous rocks; partly marine rocks, 
 indicating that the sea then spread over the region where 
 they now lie; partly coal-beds, each bed evidence that a 
 great fresh-water marsh, flat as all marshes are, for a long 
 while occupied the region of the present mountains. 
 
 Tjiere is the same evidence that the mass of the Rocky 
 Mountains had not been lifted; for marine Carboniferous 
 rocks constitute a large part of these mountains, many 
 beds containing remains of the life of the Carboniferous seas 
 that covered that part of North America. Only islands, or 
 archipelagos of islands, made by some Azoic and Paleozoic 
 ridges, existed in the midst of the wide-spread western 
 waters. 
 
 (2.) Condition in the Subcarboniferous Period. Through the 
 first period of this age the Subcarboniferous the continent 
 was almost as extensively beneath the sea as in the Devo- 
 nian age. This, again, is shown by the nature and extent 
 of the Subcarboniferous rocks, the great crinoidal lime- 
 stones. The shallow continental seas were profusely planted 
 with Crinoids amid clumps of Corals. Brachiopods were here 
 
 13 
 
140 PALEOZOIC TIME. 
 
 and there in great abundance, many lying together in beds 
 as oysters in an oyster-bed; other Mollusks, both Conchi- 
 fers and Gasteropods, were also numerous; Trilobites were 
 few; Goniatites and Nautili, along with Ganoid Fishes and 
 sharks, were the voracious life of the seas, and Amphi- 
 bian reptiles haunted the marshes. 
 
 (3.) Transition to the Carboniferous Period. Finally, the 
 Subcarboniferous period closed, and the Carboniferous 
 opened. But in the transition from the period of submerg- 
 ence to that of emergence required to bring into existence 
 the great marshes, a wide-spread bed of pebbles, gravel, and 
 sand was accumulated by the waves dashing rudely over 
 the surface of the rising continent; and these pebble-beds 
 make the Millstone grit that marks the commencement of the 
 Carboniferous period in a large part of eastern North Ame- 
 rica, especially along the Appalachian region, and also in 
 Europe. 
 
 (4.) Coal-plant Areas in the Carboniferous Period. Then 
 began the epoch of the Coal measures. 
 
 The positions of the great coal areas of North America^' 
 (see map, p. 69) are the positions, beyond question, of the 
 great marshes and shallow fresh- water lakes of the period. 
 But it is probable that the number of these marshes was less 
 than that of the coal areas. The Appalachian, Illinois, Mis- 
 souri, Arkansas, and Texas fields may have made one vast 
 Interior continental marsh-region, and those of Rhode Island, 
 Nova Scotia, and New Brunswick an Eastern border marsh- 
 region. There is some reason, however, for believing that 
 a low area of dry land (or not marshy land), extending 
 from the region of Cincinnati into Tennessee, divided the 
 Interior marsh, or at least its northern portion. 
 
 The Michigan marsh-region appears also to have had its dry 
 margins, instead of coalescing with the Illinois or Ohio areas. 
 
 It is not to be inferred that the marshes alone were 
 covered with verdure. The vegetation probably spread over 
 
CARBONIFEROUS AGE. 141 
 
 all the dry land, though making thick deposits of vegetable 
 remains only where there were marshes under dense jungle 
 growth and shallow lakes with their floating islands. 
 
 (5.) Alternations of Condition, Changes of Level. It has 
 been remarked that the many alternations of the coal- 
 beds with sandstones, shales, conglomerates, and lime- 
 stones (p. 117), are evidence of as many alternations of 
 level during the era. After the great marshes had been 
 long under verdure, the ocean began again to encroach upon 
 them, and finally swept over the whole surface, destroying 
 the land and fresh-water life of the area, that ffe, the land 
 and fresh-water Plants, Mollusks, Insects, and Reptiles, but 
 distributing at the same time the new life of the salt waters. 
 Then, after another long period of various oscillations in 
 the water-level, in which sedimentary beds in many alter- 
 nations were formed, the continent again rose to aerial life, 
 and the marshes and shallow lakes were luxuriant anew 
 with the Carboniferous vegetation. Thus the sea prevailed 
 at intervals intervals of long duration through the era 
 even of the Coal measures ; for the associated sedimentary 
 beds, as has been stated, are at least fifty times as thick as 
 the coal beds. 
 
 These oscillations continued until 3000 to 4000 feet of 
 strata were formed in Pennsylvania, and over 14,000 in 
 Nova Scotia. 
 
 The Carboniferous period w r as, therefore, ever varying 
 in its geography. A map of its condition when the great 
 coal beds were accumulating would have its eastern coast- 
 line not far inside of the present, and in the region of Nova 
 Scotia and New England even outside of the present. The 
 southern coast-line would pass through central Carolina, 
 Georgia, and Alabama, and northern Mississippi, then, west 
 of the Mississippi, around Arkansas and the bordering coun- 
 ties of Texas ; thence it would stretch northward, bounding 
 a sea covering a large part of the Rocky Mountain region, 
 
142 PALEOZOIC TIME. 
 
 for the Coal period was in that part of the continent 
 mainly a time of limestone-making. But in a map repre- 
 senting it during the succeeding times of submergence, the 
 coast-line would run through south middle New England, 
 then near the southern boundary of New York State, 
 then northwestward around Michigan, then southward 
 again to northern Illinois, and then westward and north- 
 westward to the Upper Missouri region, or the Eocky 
 Mountain sea. Through these conditions, as the extremes, 
 the continent passed several times in the course of the Car- 
 boniferous ^period. 
 
 (6.) Condition in the Permian Period. Finally, in the 
 Permian period, the Appalachian region, and the Interior 
 region east of a north-and-south line running through Mis- 
 souri, appear to have been mainly above the ocean; for the 
 Permian beds are mostly confined to the meridian of Kansas 
 and the remoter West. 
 
 GENERAL OBSERVATIONS ON THE PALEOZOIC. 
 
 1. Rocks. (1.) Maximum thickness. The maximum thick- 
 ness of the rocks of the Silurian age in North America is 
 22,000 feet; of the Devonian, about 14,000 feet; and of the 
 Carboniferous age, under 15,000 feet. 
 
 (2.) Diversities of the different Continental regions as to 
 kinds of rocks. The Paleozoic rocks of the Appalachian 
 region are mainly sandstones, shales, and -conglomerates; 
 only about one-fourth in thickness of the whole consists of 
 limestone. The rocks of the Interior continental are mostly 
 limestone, full two-thirds being of this nature. 
 
 The difference of these two regions, in this particular, 
 will be appreciated on comparing the following general sec- 
 tion of the strata of the Interior with the section, on page 
 66, of the rocks of New York, New York State lying on 
 the inner borders of the Appalachian region. The Lower 
 Silurian beds in the Mississippi basin, as the section shows, 
 
GENERAL OBSERVATIONS. 
 
 143 
 
 consist mainly of limestones; so also the Upper Silurian, 
 Devonian, and Subcarboniferous formations; and the Car- 
 boniferous of the region contains more limestone than that 
 of the East. In the Devonian of the Interior, a black shale, 
 one or two hundred feet thick, is the only representative of 
 the Hamilton group ; and a few hundred feet of sandstone 
 part of the so-called Waverly sandstone corresponds to 
 the Chemung group, or Uppermost Devonian. 
 
 In the Eastern border region, about the Gulf of St. Law- 
 rence, there is a great predominance of limestones in the 
 
 PERMIAN. 
 
 CARBONIFEROUS 
 
 SUBCARBONIFEROUS - 
 
 f HAMILTON J 
 
 (.U. HELDERBERG.... / 
 NIAGARA / 
 
 HUDSON RIVER j 
 
 TRENTON j 
 
 POTSDAM. 
 
 Permian. 
 Coal Measures. 
 
 Coal Conglomerate. 
 Subcarboniferous limestone. 
 
 Waverly sandstone (= Chemung 
 and Subcarboniferous). 
 
 Black shale. 
 Cliff limestone. 
 
 Blue limestone and shale. 
 
 Trenton limestone ; Galena lime- 
 stone ; Black River limestone. 
 
 Lower magnesian limestone ( = 
 Calciferous). 
 
 Potsdam sandstone. 
 
 Section of the Paleozoic rocks in the Mississippi basin. 
 
 formations. They prove the existence in that region of an 
 Atlantic border basin similar in some respects to the basin 
 of the Interior, the two being separated by the northern 
 part of the Appalachian region. 
 
 (3.) Diversities of the Appalachian and Interior Continental 
 regions as to the thickness of the rocks. In the Appalachian 
 
 13* 
 
144 PALEOZOIC TIME. 
 
 region the maximum thickness of the Paleozoic rocks is 
 about 50,000 feet. But this thickness is not observed at 
 any one locality, it being obtained by adding together the 
 greatest thicknesses of the several formations wherever 
 observed. The greatest actual thickness at any one place in 
 Pennsylvania is about 36,000 feet, or between 6? and 7 miles. 
 
 In the central portions of the Interior continental region, 
 the thickness varies from 3500 feet (and still less on the 
 northern border) to 6000 feet; and it is, therefore, from 
 one-sixth to one-tenth that in the Appalachian region. 
 
 (4.) Origin of the deposits. The fragmented rocks, as those 
 of sand, clay, mud, pebbles (or the sandstones, shales, 
 earthy sandstones and conglomerates), were made from the 
 wear of pre-existing rocks under the action of water. The 
 water was mainly that of the ocean, and the power was 
 that of the waves and currents. The material acted upon 
 was subjected to wave-action, and must have been at or 
 near the surface. The material of the coarser rocks may 
 have been accumulating where the waves were dashing 
 against a beach or an exposed sand-reef, or else where cur- 
 rents were in rapid movement over the bottom ; for accumu- 
 lations of pebbles and coarse sand are now made under 
 these circumstances. The material of the earthy sandstones 
 may have been the mud or earthy sands forming the bottom 
 of shallow seas. The fine clayey or earthy deposits must 
 have been made in sheltered bays or interior seas, in which 
 the waves were light, and, therefore, fitted to produce by 
 their gentle attrition the finest of mud ; or else in the deeper 
 off-shore waters, where the finer detritus of the shores is 
 liable to be borne by the currents. 
 
 Accumulations of any degree of thickness may be made 
 in shallow waters, provided the region is undergoing very 
 slow subsidence ; for in this way the depth of the waters 
 may be kept sufficient to allow of constantly increasing 
 depositions. Thus, by a slow subsidence of 1000 feet, 
 
GENERAL OBSERVATIONS. 145 
 
 deposits 1000 feet thick may be produced, and the depth of 
 water at no time exceed 20 feet. The occurrence of ripple- 
 marks, mud-cracks, or rain-drop impressions in many beds 
 of most of the formations, proves that the layers so marked 
 were successively near the surface, and, therefore, that there 
 must have been a gradual sinking of the bottom as the beds 
 were formed. 
 
 The limestones of the Paleozoic were probably made, in 
 every case, out of organic remains, as Shells, Corals, Crinoids, 
 etc., and perhaps in some cases (as that of the Lower Mag- 
 nesian limestones of the Interior) out of minute Rhizo- 
 pods, which are known to have formed, to a large extent, 
 the chalk-beds of Europe. Shells, Corals, and Crinoids 
 must be ground up by the waves to form fine-grained rocks ; 
 while the shells of Rhizopods are so minute as to be already 
 fine grains, and may become compact rocks by simple con- 
 solidation. 
 
 The hornstone in the limestones, as remarked on page 109, 
 may be wholly of organic origin. 
 
 2. Time-Ratios. Judging from the maximum thickness of 
 the rocks of the several Paleozoic ages in North America, 
 and allowing that five feet of fragmental rocks may accumu- 
 late in the time required for one foot of limestone, the rela- 
 tive lengths of the Silurian, Devonian, and Carboniferous 
 ages were not far from 3:1:1, and the Lower Silurian era 
 was four times as long as the Upper. 
 
 Thus time moved on slowly in the earth's first beginnings. 
 The condition of the earth in an age of Mollusks, when 
 only Invertebrates and Sea-weeds were living, when all 
 life was the life of the waters, and nothing existed above the 
 ocean's level, was very inferior to that of the Carbonif- 
 erous, when the continents had their forests, the waters 
 their fishes, and the marshes their reptiles. Yet the length 
 of the time through which the earth was groping under 
 the first-mentioned condition was at least three times that 
 
146 PALEOZOIC TIME. 
 
 under the last ; and the earlier Lower Silurian era was four 
 times as long as the Upper Silurian. Such was the divine 
 system in the progress of creation. Such is time in the 
 view of the infinite Creator. 
 
 3. Geography. (1.) Close, of Azoic time. The map on page 
 73 shows approximately the outline of the dry land of 
 North America at the close of Azoic time. The only moun- 
 tains were Azoic mountains, "the principal of which were 
 the Laurentian of Canada and the Adirondack of northern 
 New York. We cannot judge of the height of these moun- 
 tains then from what we now see, after all the ages of 
 Geology have passed over them, for the elements and run- 
 ning water have never ceased action since the time of their 
 uplift, and the amount of loss by degradation must have 
 been very great. 
 
 (2.) General Progress through Paleozoic time. The increase 
 of dry land during the Paleozoic has been shown (pp. 99, 
 115) to have taken place mainly along the borders of the 
 Azoic, so that the old nucleus has been on the gradual 
 increase. This increase is well marked from north to south 
 across New York. At the close of the Lower Silurian, the 
 shore-line was not far from the present position of the 
 Mohawk, showing but a slight extension of the dry land in 
 the course of this very long era ; when the Upper Silurian 
 ended, the shore-line extended along 15 or 20 miles south of 
 the Mohawk. When the Devonian ended and the Carbonif- 
 erous age was about opening, the coast-line was just north 
 of the Pennsylvania boundary. Thus, the dry part of the 
 continent was on the slow increase. 
 
 The progress southward was at an equal rate in Wis- 
 consin, where there is an isolated Azoic region like that of 
 northern New York. In the intermediate district of Michi- 
 gan, the coast made a deep northern bend through the Silu- 
 rian and Devonian. In the Carboniferous the same great 
 Michigan bay existed during the intervals of submergence; 
 
GENERAL OBSERVATIONS. 147 
 
 but it was changed to a Michigan marsh or fresh-water lake, 
 filled with Goal-measure vegetation during the intervening 
 portions of the Carboniferous period ; and at the same 
 times, as explained on page 140, the continent east of the 
 western meridian of Missouri had nearly its present extent, 
 though not its mountains or its rivers. 
 
 (3.) Regions of rock-making, and their differences. The sub- 
 merged part of the continent was the scene of nearly all 
 the rock-making ; and this work probably went on over its 
 whole wide extent. 
 
 The rocks, as partially explained on page 144, varied in 
 kind with the depth and with the exposure to the open sea. 
 
 This Interior continental region, which was for the most of 
 the time a great interior oceanic sea, afforded the conditions 
 fitted for the growth of corals and crinoids and other clear- 
 water species, and hence for the making of limestone reefs 
 out of their remains ; for limestones are the principal rocks 
 of the interior. Yet there were oscillations in the level; for 
 there are abrupt transitions in the limestones, and some 
 sandstones and shales alternate with them. But these oscil- 
 lations were not great, the whole thickness of the rocks, as 
 stated on page 144, being small. 
 
 The Appalachian region, on the contrary, presented the 
 conditions required for /fragmental deposits. It was ap- 
 parently a region of immense sand-reefs and mud-flats, 
 with bays, estuaries, and extensive submerged plateaus or 
 off-shore soundings, such as might have existed in the face 
 of the ocean. Here, too, the change of level was very great; 
 for within this region occur the 6 to 7 miles of Paleozoic 
 formations (p. 144), and even 9 miles, reckoning the maxi- 
 mum amount of all the deposits. This vast thickness indi- 
 cates that while there were various upward and downward 
 movements over this Appalachian region through Paleozoic 
 time, the downward movements exceeded the upward even 
 by the amount just stated. These movements, moreover, were 
 
148 PALEOZOIC TIME. 
 
 in progress from the Potsdam period onward; the forma- 
 tions of nearly every period in the series exceed 8 to 10 
 times the thickness they have over the Interior region. 
 
 (4.) Mountains of Paleozoic origin. The mountains in 
 eastern North America, made in the course of the Paleozoic 
 ages, were few. Those of the region south of Lake Supe- 
 rior about Keweenaw Point, and to the west, probably rose 
 during the latter part of the Potsdam period. The Green 
 Mountain region became dry land after the Lower Silurian 
 (p. 91) ; but there is no reason to believe that it was very 
 much raised; for the eastern half of Yermont was beneath 
 the ocean, and became covered by coral reefs and other 
 formations during the Devonian age. The Devonian beds 
 of the vicinity of Gaspe may have been raised into ridges 
 before the Carboniferous age began. But the larger part 
 of the continental area was still without mountains. The 
 Rocky chain had only some ridges as islands in the seas, 
 and the Appalachians were yet to be made. 
 
 (5.) Rivers Lakes. The depression between the New 
 York and the Canada Azoic, dating from the Azoic age, 
 was the first indication of a future St. Lawrence channel. 
 It continued to be an arm of the sea, or deep bay, through 
 the Silurian, and underwent a great amount of subsidence 
 as it received its thick Canadian formations. After the 
 Silurian age, marine strata ceased to form, indicating 
 thereby that the sea had retired ; and fresh waters, derived 
 from the Azoic heights of Canada and New York, probably 
 began their flow along its upper portion, and emptied into 
 the St. Lawrence Gulf of the time not far below Montreal. 
 
 The raising of New York State out of water at the close 
 of the Devonian suggests that from that time the Hudson 
 valley was a stream of fresh water. The valley itself, and 
 its continuation north as the Champlain valley, date from 
 the close of the Lower Silurian. 
 
 The Mississippi and its tributaries, east and west, were 
 
GENERAL OBSERVATIONS. 149 
 
 not in existence in the Paleozoic ages. In the intervals 
 of Carboniferous verdure, when the continent was emerged, 
 the Ohio and Mississippi basin were regions of great 
 marshes, lakes, and bayous, and not of great rivers; for 
 rivers could not exist without a head of high land to supply 
 water and give it a flow. 
 
 Lake Superior was a district of vast rock-deposits and 
 extensive igneous eruptions in the Potsdam j eriod, or near 
 the close of that period, as well as in the closing Azoic ; and 
 the thick accumulations show that deep subsidences were 
 then in progress there, as also in the region of the St. 
 Lawrence; so that we may infer that the basin of this 
 great lake was already in process of formation before the 
 Lower Silurian closed. The extent and position of the great 
 Michigan bay through the Silurian and Devonian ages and 
 much of the Carboniferous, as mentioned on pp. 99, 142, 
 show that Lakes Erie, Huron, and Michigan were then 
 within the limits of this bay. Whether deeper or not than 
 other portions of the bay, is not known. 
 
 Thus, Geology studies the Geography of the Paleozoic 
 ages, and traces North America through its successive 
 stages of growth. 
 
 4. Climate. ~No evidence has been found through the 
 Paleozoic records of any marked difference of temperature 
 between the zones. In the Carboniferous age the Arctic 
 seas had their Corals and Brachiopods, and the Arctic lands 
 their forests and marshes under dense foliage, no less than 
 those of America and Europe. The facts on this subject 
 are stated on p. 138. 
 
 5. Life. (1.) Appearance and disappearance of species. 
 "With each new period in the progressing ages, new living 
 species were introduced; and, as each period ended, the old 
 more or less completely passed away, or were exterminated. 
 There were also partial destructions attending the many 
 minor changes in the rock-formations, as in the transition 
 
150 
 
 PALEOZOIC TIME. 
 
 from the formation of a bed of shale to that of sandstone 
 or of limestone, or the reverse ; and sonie new species made 
 their appearance with each new stratum. Thus, destruc- 
 tions and creations took place at intervals through the 
 whole course of the ages. 
 
 (2.) T\e exterminations indicated not in harmony with any 
 development-theory. This extermination of the life of a 
 period or epoch, according to the evidence gathered from 
 the rocks, cut short not only species, but genera, families, and 
 tribes; -void yet these same genera and tribes were often 
 begun again by other species, and so continued on. Had 
 the system of creation been dependent on the development 
 of species from species, this would have been impossible. The 
 system could not have withstood the disasters it had to 
 encounter. 
 
 (3.) Beginning and ending of genera, families, and higher 
 groups. The following table of the tribe of Trilobites illus- 
 trates the general character of the progress which took 
 place in this and other groups : 
 
 TRILOBITES.. 
 
 Paradoxides, Conocephalus, Sao, Ellipso- 
 cephalus, Hydrocephalus, Dicelloc 
 phalus, Arionellus, Menocephalus, Ba- 
 thyurus 
 
 Olenua and Agnostus. 
 Ogygia 
 
 Trinucleus, Asaphus, Remopleurides, 
 Amphion, and Triarthrus 
 
 Calymene, Ampyx, Illaenus, Acidaspis, 
 and Cheirurus 
 
 Homalonotus and Lichas 
 
 Phillipsia, Griffithides 
 
GENERAL OBSERVATIONS. 151 
 
 The vertical columns correspond to the Lower and Upper 
 Silurian, the Devonian, and the Carboniferous. The left- 
 hand column under Lower Silurian corresponds to the first, 
 or Primordial period; and the three columns under the 
 Carboniferous, to the Subcarboniferous, Carboniferous, and 
 Permian periods of the age. The widths of the columns are 
 made to represent, as nearly as possible, the relative lengths 
 of the eras. Opposite TRILOBITES, the black area shows 
 that the tribe began with the beginning of the Paleozoic 
 and continued nearly to its end. Next there are the names 
 of nine genera which existed only in the Primordial Period, 
 each having then one or many species, but none afterwards. 
 Then there are two genera, Olenus and Agnostus, which con- 
 tinued from the Primordial through the Lower Silurian. 
 Then, others confined to the rest of the Lower Silurian ; 
 others that passed into the Upper Silurian, then to become 
 extinct; others that continued into the Devonian; and two 
 genera confined to the Carboniferous. These genera included 
 more than 500 species. Of the Carboniferous genera the 
 last species had been exterminated before the close of the 
 
 In a similar manner the genera and families of Brachio- 
 pods began at different periods or epochs, and continued on 
 for a while, to become, in general, extinct. Many genera 
 ended in the course of the Paleozoic and at its close ; only 
 a few continued into later periods. 
 
 (4.) Long-lived genera. Two Lower Silurian genera of 
 Brachiopods continue from the Primordial period, not 
 only through Paleozoic and Mesozoic time, but onward to 
 the present age, having species in existing seas. They are 
 Lingula and Discina. It will be noted that these genera 
 survived through the long ages of the past, not by the 
 uninterrupted existence of any of their species, but by the 
 perpetuating of the type of form and structure character- 
 izing the genera in a succession of distinct species. 
 
 14 
 
152 PALEOZOIC TIME. 
 
 (5.) Unity of plan in nature. These long generic lines, 
 stretching on with such uniformity from the very begin- 
 nings of life on the globe, are proofs of the unity of plan 
 through the system of creation. 
 
 (6.) Permanency of types, notwithstanding the influence of 
 external causes. As this uniformity has remained in spite of 
 the vast physical changes the globe has undergone since life 
 began, it is evidence of the strongest kind as to the little 
 power which external causes have towards producing 
 changes in types. 
 
 The facts bear abundant testimony to a Creating Power 
 above nature, carrying forward a preordained plan. More- 
 over, there is evidence even in the Paleozoic records their 
 coal-beds, iron-ores, and the system of life in progress of 
 expansion that this plan involved the future existence of 
 a being that should have knowledge to use the coal and iron, 
 and power to read the records and discern in God's marvel- 
 lous works His wisdom and beneficence. 
 
 (7.) General characteristics of Paleozoic life. Both plants 
 and animals were marine through, or till near the close of, the 
 Silurian age. In the Devonian age there were terrestrial 
 plants and animals, and a still greater diversity of life over 
 the land in the Carboniferous. The characteristics of the 
 life of the Silurian age are mentioned on page 103; of that 
 of the Devonian, on page 115; and of that of the Carbonif- 
 erous, on page 125. 
 
 (8.) Special Paleozoic peculiarities of the life. The follow- 
 ing facts show in what respects the life of the Paleozoic 
 ages was peculiarly ancient : 
 
 a. Not only are the species all extinct, but almost every 
 genus. But 15 or 16 of the genera which existed in the 
 course of the Paleozoic have living species; and all these 
 are Molluscan. 
 
 b. Among Eadiates, the Polyps were largely of the tribe 
 of Cyathophylloid corals, which is exclusively ancient, or 
 
GENERAL OBSERVATIONS. 153 
 
 Paleozoic, not a species having lived after the close of the 
 Carboniferous age. The Echinoderms were mostly Cri- 
 noids, and these were in great profusion. Crinoids were 
 far less abundant, and of different genera, in the Mesozoic ; 
 and now, very few exist. 
 
 c. Among Mollusks, Brachiopods were exceedingly abun- 
 dant : their fossil shells far outweigh those of all other Mol- 
 lusks. They were much less numerous than other Mollusks 
 in the Mesozoic; and at the present time the group is nearly 
 extinct. The Cephalopods were represented very largely 
 by Orthocerata, but few species of which existed in the early 
 Mesozoic, and none afterwards. 
 
 d. Among Articulates, Trilobites were the most common 
 Crustaceans, a, group exclusively Paleozoic. 
 
 e. Among Vertebrates, the Devonian Fishes were either 
 Ganoids or Selachians, and the Ganoids were the heterocer- 
 cal species. Of heterocercal Ganoids, but few species lived 
 in the first period of the Mesozoic; and the whole group of 
 Ganoids is now nearly extinct. Of the Selachians, a large 
 proportion were Cestracionts, a tribe common in the Meso- 
 zoic, but now nearly extinct. 
 
 /. Among terrestrial Plants, there were Lepidodendra, 
 Sigillarife, Calamites in great profusion, making, with Coni- 
 fers and Ferns, the forests and jungles of the Carboniferous 
 and later Devonian: no Lepidodendron or Sigillaria existed 
 afterwards, and the Calamites ended in the Mesozoic. 
 
 Thus, the Paleozoic or ancient aspect of the animal life 
 was produced through the great predominance of Brachio- 
 pods, Crinoids, Cyathopliylloid Corals, Orthocerata, Trilobites, 
 and heterocercal Ganoids; and that of the plants over the 
 land, through the Lepidodendra, Sigillaria^, and Calamites, 
 along with Ferns and Conifers. In addition to this should 
 be mentioned the absence of Angiosperms and Palms among 
 Plants ; the absence of Teliost Fishes, Birds, and Mammals, 
 
154 PALEOZOIC TIME. 
 
 among Yertebrates ; and of nearly all modern tribes of genera 
 among Radiates, Mollusks, and Articulates. 
 
 y. Mesozoic and Modern types begun in Paleozoic time. The 
 principal Mesozoic type which began in the Paleozoic was 
 the Reptilian. But besides Reptiles there were the first of 
 the Decapod Crustaceans; the first of Oysters; and the first 
 of the great tribe of Ammonites, the Goniatites being of this 
 tribe. 
 
 The type of Insects, or terrestrial Articulates, belongs 
 eminently to modern time; for it has now its fullest dis- 
 play. It dates from the existence of terrestrial plants 
 in the Devonian. 
 
 Thus, while the Paleozoic ages were progressing, and the 
 types peculiar to them were passing through their time of 
 greatest expansion in numbers and perfection of structure, 
 there were other types introduced which should have their 
 culmination in a future age. The Reptiles and Goniatites 
 of the later Paleozoic were precursors of the Age of Rep- 
 tiles which followed, in accordance with the principle exem- 
 plified in all history, that the characteristics of an age com- 
 mence to appear in the age preceding. 
 
 DISTURBANCES CLOSING PALEOZOIC TIME. 
 
 1. General quiet of the Paleozoic Ages. The long ages of 
 the Paleozoic passed with but few and comparatively small 
 disturbances of the strata of eastern North America. There 
 were some early permanent uplifts in the Lake Superior 
 region, and along the course of the Green Mountains, and 
 some later in the district of Gaspe near St. Lawrence Bay ; 
 there was, through the ages, a gradual increase on the north 
 vin the amount of dry land; there were, through parts of all 
 the periods, slow oscillations in progress, varying the water- 
 level and favoring the increasing thickness of the rocks, 
 and their successive variations as to kind and extent. But 
 these changes were probably caused by exceedingly slow 
 movements of the earth's crust, probably less than a foot 
 
APPALACHIAN REVOLUTION. 155 
 
 a century. There may have been occasional quakings of 
 the earth, even exceeding the heaviest of modern earth- 
 quakes. There may have been at times sudden raisings or 
 sinkings of the continental crust. But, while there were some 
 uplifts, as above mentioned, there is nothing in the condition 
 of the strata indicating a general or extensive upturning. 
 
 2. The Appalachian the region of greatest change of level 
 through the Paleozoic Ages. The region of greatest move- 
 ment during these ages was the Appalachian. For it has 
 been shown that the oscillations which there took place 
 resulted in subsidences of one or more thousand feet with 
 nearly every period of the Paleozoic. The oscillations 
 ceased in the Green Mountain portion after the close of the 
 Lower Silurian era, but not until the subsidence there had 
 reached at least 10,000 feet; and in Pennsylvania and Vir- 
 ginia they continued through a large part of the Carbonif- 
 erous Age, until the sinking amounted to 35,000 or 38,000 
 feet. But all this sinking was probably quiet in its progress, 
 as is proved by the regularity in the series of strata. 
 
 The thickness of the coal-beds indicates that the coal- 
 plant marshes were long undisturbed, and therefore that 
 long periods passed without appreciable movement. 
 
 3. Approach of the epoch of Appalachian revolution. The 
 era of comparative quiet alluded to came gradually to a 
 close as the Carboniferous age was terminating, and an 
 epoch of upturning, metamorphism, and mountain-making 
 began. There are mountains to testify to this both in 
 Europe and America. 
 
 In eastern North America the disturbances affected the 
 Appalachian region and Atlantic border from Newfoundland 
 to Alabama, and the Appalachian mountains are a part of 
 the result. The epoch is hence appropriately styled the 
 epoch of the Appalachian revolution. The region in eastern 
 America of the deepest Paleozoic subsidence and of the 
 thickest accumulation of Paleozoic rocks was now the 
 
 14* 
 
156 CLOSE OF PALEOZOIC TIME. 
 
 region of the profoundest disturbances and the greatest 
 uplifts. 
 
 4. Effects of the disturbances. The following are among 
 the effects of the disturbances along the Appalachian region 
 and Atlantic border : 
 
 (1.) Strata were upraised and flexed into great folds, 
 many of the folds a score or more of miles in span. 
 
 (2.) Deep fissures of the earth's crust were opened, and 
 faults innumerable were produced, some of them of 10,000 
 to 20,000 feet. 
 
 (3.) Eocks were consolidated; and, over a large part of 
 New England and the more southern Atlantic border, sand- 
 stones and shales were crystallized into granite, gneiss, 
 mica and argillaceous schist and other related rocks, and 
 limestone into architectural and statuary marble. 
 
 (4.) At the same time, the crystallized and consolidated 
 rocks had their fractures filled with mineral material mak- 
 ing veins, some of them being filled with rock alone, mak- 
 ing veins of quartz, granite, etc.; others with rock and 
 associated metallic minerals, making metallic veins, as of 
 lead-ore, copper-ore, gold; others were made containing 
 gems, as topaz, beryl, and the like. Diamonds, also, are 
 among the results of the metamorphism. 
 
 (5.) Bituminous coal was turned into anthracite in Penn- 
 sylvania and Rhode Island. 
 
 (6.) In the end, the Appalachian mountains were made. 
 
 5. Evidence of the flexures, uplifts, and metamorphism. 
 The evidence that the rocks of the Appalachian region and 
 Atlantic border were flexed, uplifted, faulted, and otherwise 
 changed from their original condition, is as follows : 
 
 The Coal measures and other Paleozoic strata, though 
 originally spread out in horizontal beds, are now in an 
 uplifted and flexed or folded condition; and they are so 
 involved together in one system of flexures and uplifts that 
 
APPALACHIAN REVOLUTION. 
 
 157 
 
 the whole must have been the result of one system of move- 
 ments. Figures 250-253 illustrate this. 
 
 Fig. 250. 
 
 Section of the Coal measures, near JNesquehoniug, Pa. 
 
 Fig. 250 shows the condition of the Anthracite coal-beds 
 of Mauch Chunk in Pennsylvania. Some of the upturned 
 
 Fig. 251. 
 
 Section on the Schuylkill, Pa.; P. Pottsville on the Coal measures; 2, Calciferous formation; 
 3, Trenton; 4, Hudson River; 5, Oneida and Niagara; 7, Lower Helderberg; 8, 10, 11, 
 Devonian ; 12, 13, Subcarboniferous ; 14, Carboniferous, or Coal measures. 
 
 beds, as is seen, stand nearly vertical. Fig. 251 is from 
 another locality near Pottsville in the same State. The coal 
 
 Fig. 252. 
 
 r S.E. 
 
 Section from the Great North to the Little North Mountain through Bore Springs, Va.; t, t, 
 position of thermal springs; n, Calciferous formation; in, Trenton; IV, Hudson River; 
 v, Oneida; vi, Clinton and Lower Helderberg; vn, Oriskany Sandstone and Cauda-Galli 
 Grit. 
 
 beds are the upper ones below 14; the rest are the beds 
 of the Upper and Lower Silurian (2 to 7) ; the Devonian (8, 
 10, 11), and Subcarboniferous (12, 13). Fig. 252 was taken* 
 from the vicinity of Bore Springs in Virginia, and includes 
 Silurian and Devonian beds : it shows well the folded cha- 
 
158 CLOSE OP PALEOZOIC TIME. 
 
 racter of the rocks. Fig. 253 represents one of the great 
 faults in southern Yirginia (between Walker's Mountain and 
 
 Fig. 253. 
 
 Section of the Paleozoic formations of the Appalachians in southern Virginia, between 
 Walker's Mt. and the Peak Hills (near Peak Creek Valley) : F, fault ; a, Lower Silurian 
 limestone ; 6, Upper Silurian ; c, Devonian ; d, Subcarboniferous, with coal beds. 
 
 Peak Hills) ; the break is at F, and along it the rocks on the 
 left were shoved up along the sloping fracture until a Lower 
 Silurian limestone (a) was on a level with the Subcarbonif- 
 erous formation (d), a fault of at least 10,000 feet. Such 
 examples are in great numbers throughout the Appalachians. 
 In many of the transverse valleys the curves may be traced 
 for scores of miles. 
 
 As shown in the above sections (figs. 250-253), the folds, 
 instead of remaining in regular rounded ridges with even 
 synclinal valleys between, such as the flexing of the strata 
 might make, have been to a great extent worn away, or 
 modelled into new ridges and valleys, by the action of waters 
 during subsequent time ; and often what was the top of a fold 
 is now the bottom of a valley, because the folds would be most 
 broken where most abruptly bent, that is, along the axes 
 of flexure, and hence would be most liable in this part to be 
 cut away or gorged out by any denuding causes. The figures 
 on page 41 illustrate still further the condition of folded 
 strata before and after denudation. Some of the Appala- 
 chian folds were probably 20,000 feet in height above the 
 present level of the ocean, or would have had this height if 
 they had remained unbroken, while in fact the loftiest sum- 
 mits now are less than 7000 feet, and few exceed 5000 feet. 
 
 Over New England there are similar flexures. Those of 
 
APPALACHIAN REVOLUTION. 159 
 
 the Ehode Island coal formation are very abrupt, and full 
 of faults, the coal-beds being much broken and displaced. 
 Through eastern Yermont, and in Massachusetts for some 
 distance west of the Connecticut River, there are Devonian 
 strata in the same condition; although the rocks are in 
 general crystalline, Devonian fossils have been found at 
 Bernardston in Massachusetts, and on Lake Memphremagog. 
 At the latter place there was once a coral-reef (p. 105). It 
 is inferred from the facts that even the granites, gneiss, and 
 slates of the White Mountains, and the gneiss of Haddam, 
 Connecticut, were originally Devonian sedimentary strata, 
 and that all New England is made of folded and meta- 
 morphosed Paleozoic rocks. 
 
 Similar facts might be cited from Nova Scotia on the 
 north and Alabama on the south, proving that a region 1000 
 miles in length along the Atlantic border, from Newfound- 
 land to the Gulf States, participated in the grand movement. 
 
 6. General truths with regard to the results. The following 
 are some of the general truths connected with the uplifts 
 and metamorphism : 
 
 (1.) The courses of the flexures and of the outcrops or 
 strike, and those of the great faults, are approximately 
 northeast, or parallel to the Atlantic border. There is a 
 bend eastward in Pennsylvania corresponding with the 
 eastward bend of the southern coast of New England, and 
 then a change to the northward in New England. 
 
 (2.) The folds have their steepest slope towards the north- 
 west, or away from the ocean. If fig. 41 (page 42) represent 
 one of the folds, the left would be the ocean side, or that to 
 the southeast, and the right the landward side, or that to 
 the northwest. 
 
 (3.) The flexures are most numerous and most crowded 
 on that side of the Appalachian region which is towards the 
 ocean, and diminish westward. There is seldom, however, 
 a gradual dying out westward, the region of disturbance 
 
160 CLOSE OP PALEOZOIC TIME. 
 
 being often bounded on the west by one or more of the 
 great fractures and faults, as in eastern Tennessee and along 
 the valley of the Hudson. 
 
 (4.) The wearing away of the summits of the folds when 
 crowded together produces a series of southeast dips, as 
 illustrated in figures 41, 42 (p. 42). Such southeast dips, 
 not looking as if they were ever due to folds, characterize 
 the rocks of much of New England and the eastern part of 
 the Appalachian region. 
 
 (5.) The metamorphism of the strata is more extensive 
 and complete to the eastward (or towards the ocean) than 
 to the westward. 
 
 (6.) The change of bituminous coal to anthracite, by an 
 expulsion of the bitumen, was most complete -jphere the 
 disturbances were greatest, that is, in the Eastern coal 
 regions. The anthracite region of Pennsylvania (see map, 
 p. 118) owes its broken character partly to the uplifts and 
 partly to denudation. To the westward, the coal is first 
 Bemibituminous, and then, as at Pittsburg, true bituminous. 
 In Eh ode Island, where the associated rocks are partly true 
 metamorphic or crystalline rocks and the disturbances arQ 
 very great, the coal is an excessively hard anthracite, and 
 in some places is altered to graphite (an effect which may 
 be produced in ordinary coal by the heat of a furnace). The 
 bed of graphite near Worcester in Massachusetts is sup- 
 posed to be an altered coal seam. 
 
 7. Conclusions. These facts lead to the following conclu- 
 sions : 
 
 (1.) The movement producing these vast results was due 
 to lateral pressure, the folding having taken place just as it 
 might in paper or cloth under a lateral or pushing movement. 
 
 (2.) The pressure was exerted at right angles to the 
 courses of the folds, as is the case when paper is folded in 
 the manner mentioned. 
 
 (3.) The pressure was exerted from the ocean side of the 
 
APPALACHIAN REVOLUTION. 161 
 
 Appalachians ; for the results in foldings and metamorphism 
 are most marked towards the ocean. 
 
 (4.) The force was vast in amount. 
 
 (5.) The force was slow in action and long continued, and 
 not abrupt or paroxysmal as when a wave or series of 
 waves is thrown up by an earthquake shock on the surface 
 of an ocean. For the strata were not reduced by it to a 
 state of chaos, but retain their stratification, and show com- 
 paratively little confusion, even in the regions of greatest 
 disturbance and alteration. 
 
 (6.) The action of the force was connected with the emis- 
 sion of heat. For without some heat above the ordinary 
 temperature, it is not possible to account for the consolida- 
 tion an^crystallization of the rocks. 
 
 (7.) The history of the Appalachian Mountains stretches 
 through all the geological ages from the Azoic onward. 
 Through the Silurian, Devonian, and Carboniferous ages, 
 the formations were accumulating to a great thickness, 
 while slow oscillations of level were in progress. "When the 
 Carboniferous age was closing, these oscillations, which had 
 resulted in a subsidence of several miles, began to culminate 
 in pro founder movements, producing flexures of the earth's 
 crust, uplifts, faults, consolidation, and metamorphism, and 
 ending in the elevation of the mountains. And finally, during 
 these upliftings, moving waters commenced the work of 
 denudation, the chiselling of the heights, which has con- 
 tinued to the present time. 
 
 8. Disturbances on other continents. The amount of cotem- 
 poraneous mountain-making over the globe at this epoch 
 has not yet been clearly made out. Enough is known to 
 render it probable that the Ural Mountains, with their 
 veins of gold and platinum, were made at the same time 
 with the Appalachians, and that uplifts and metamorphism 
 also occurred in other parts of Europe, and in Great Bri- 
 tain. Murchison states that the close of the Carboniferous 
 
162 MESOZOIC TIME. 
 
 period was specially marked by disturbances and uplifts ; 
 that it was then " that the coal strata and their antecedent 
 formations were very generally broken up, and thrown, by 
 grand upheavals, into separate basins, which were fractured 
 by numberless powerful dislocations/' 
 
 The epoch of the Appalachian revolution was, then, a 
 grand epoch for the world. The -complete extermination of 
 life which took place at the time was probably a consequence 
 of these great physical changes progressing over the earth's 
 surface. The Appalachian Mountains stand up as boldly 
 between Paleozoic and Mesozoic time as between the ocean 
 and the Interior Continental basin. 
 
 HI. MESOZOIC TIME. 
 
 1. Ages. Mesozoic or medieval time, in Geological his- 
 tory, comprises but one age, the EEPTILIAN. In the course 
 of it, the class of Reptiles passed its culminations; that is, 
 its species increased in numbers, size, and diversity of forms, 
 until they vastly exceeded in each of these respects the 
 Eeptiles of either earlier or later time. 
 
 2. Area of progress in rock-making. The area of rock- 
 making in North America, during Mesozoic time, was some- 
 what different from what it was in Paleozoic. Then, nearly 
 the whole continent, outside of the northern Azoic, was 
 receiving its successive formations; and the three great 
 regions were the Eastern border, the Appalachian, and the 
 Interior Continental. By the close of the Paleozoic era, the 
 Appalachian region and the Interior east of the Mississippi, 
 excepting its southern portion, had become part of the dry 
 land of the continent, as is shown by the absence of marine 
 strata of later date. The great areas of progress were con- 
 sequently changed, and became (1) the Atlantic border, 
 (2) the Gulf border, and (3) the Western Interior, or region 
 
REPTILIAN AGE. 163 
 
 west of the Mississippi. In other words, the continent, from 
 the Mesozoic onward, until the close of the Tertiary period 
 in the Cenozoic, was receiving its new marine formations 
 only along its borders and over the part of the Interior 
 region which covers the present site of the slopes of the 
 Rocky Mountains. 
 
 These three regions are continuous with one another, the 
 Atlantic connecting with the Gulf border region on the 
 south, and the Gulf border region passing northwestward 
 into the Western Interior or Rocky Mountain region. 
 
 In Europe no analogous change can be distinguished; for 
 the continent was, from the first, an archipelago; and it 
 continued to bear this geographical character, though with 
 an increasing prevalence of dry land, until the Cenozoic era 
 had half passed. Western England then stood as three or four 
 islands above the sea (the area marked as covered by Paleo- 
 zoic rocks on the map, p. 120), and the area of future rock- 
 making was mainly confined to the intervals between these 
 islands and to the submerged area on the east and southeast; 
 and it is probable that this area and a portion of northeast- 
 ern France were part of a large German-Ocean basin. 
 
 REPTILIAN AGE. 
 
 Periods. The Reptilian Age includes tljree periods : 
 
 1. TRIASSIC : named from the Latin tria, three, in allusion 
 to the fact that the rocks of the period in Germany consist 
 of three separate groups of strata. This is a local subdivi- 
 sion, not characterizing the rocks in Britain or in most 
 other parts of Europe. 
 
 2. JURASSIC : named from the Jura Mountains, situated 
 on the eastern border of France, between France and 
 Switzerland, where rocks of the period occur. 
 
 3. CRETACEOUS : named from the Latin creta, chalk, the 
 chalk beds of Britain and Europe being included in the 
 Cretaceous formation. 
 
 15 
 
164 MESOZOIC TIME REPTILIAN AGE. 
 
 1. TRIASSIC AND JURASSIC PERIODS. 
 1. Rocks: kinds and distribution. 
 
 The American rocks of the Triassic period have not yet 
 been separated from those of the Jurassic, except in a few 
 points west of the Mississippi. 
 
 In the Atlantic border region, these Mesozoic rocks occupy 
 narrow ranges of country parallel with the Appalachian 
 chain, following its varying courses. One of these ranges 
 occupies the valley of the Connecticut between northern 
 Massachusetts and New Haven on Long Island Sound, 
 and runs parallel with the Green Mountains : it has a 
 length of about 110 miles. Another the longest of them 
 commences at the north extremity of the Palisades, on 
 the west bank of the Hudson River, and stretches south- 
 westward through New Jersey, Pennsylvania (here bending 
 much to the westward, like the Appalachians of the State, 
 as shown in the map on page 118), and reaching far into the 
 State of Yirginia. Another stretches almost in the line of 
 the last through North Carolina. There is another along 
 western Nova Scotia. These, and some other smaller areas, 
 are indicated on the map on p. 69 by an oblique lining in 
 which the lines run from the right above to the left below. 
 
 The rocks are mainly sandstones and conglomerates, but 
 include some considerable beds of shale, and in some places 
 a bed of impure limestone. The sandstones are generally 
 red or brownish-red. The freestone of Portland, near Middle- 
 town in Connecticut, and of Newark in New Jersey, are 
 from the formation. The pebbles and sand of the beds were 
 derived from the granites, gneiss, schists, etc. that were 
 crystallized in the epoch of the Appalachian revolution; 
 and in some of the coarser kinds large stones of granite and 
 mica schist may be taken from the layers. The strata 
 overlie directly, but unconformably, these metamorphic 
 rocks. Near Richmond in Yirginia and in North Carolina 
 
TRIASSIC AND JURASSIC PERIODS. 165 
 
 there are valuable coal-beds in this formation. The coal is 
 bituminous. 
 
 The several ranges of this sandstone formation are 
 remarkable for the great number of trap ridges and trap 
 dikes intersecting them (p. 30). Mount Holyoke in Massa- 
 chusetts, East and West Rocks near New Haven in Connec- 
 ticut, and the Palisades on the Hudson, are a few examples 
 of these trap ridges. Trap is an igneous rock, one that was 
 ejected in a melted state from a deep-seated source of fire, 
 through fissures made by fracturing the earth's crust. The 
 dikes and ridges are exceedingly numerous, and have the 
 same general course with the sandstone ranges. They are 
 so associated with the sandstone formation that there 
 appears to be some connection in origin between the water- 
 made and the fire-made rocks. The proofs that the trap 
 came up through the fissures in a melted state are abundant'; 
 for the wall-rock of the fissures is often baked so as to 
 be very hard, and is sometimes filled with crystallizations, 
 as of epidote or tourmaline, evidently due to the heat. 
 
 West of the Mississippi that is, in the Western Interior 
 region there is a sandstone formation containing much 
 gypsum (and hence called the Gypsiferous formation), which 
 is barren of fossils, except an occasional fragment or trunk 
 of fossil wood and some Reptilian remains. It probably 
 spreads widely over the Rocky Mountain region beneath 
 the later beds. It comes out to view on the western borders 
 of Kansas, and also in the Colorado region beyond the sum- 
 mit of the Rocky Mountains. Owing to the absence of 
 marine fossils, it has not been determined whether the 
 formation is Triassic, lower Jurassic, or both united. 
 
 In the vicinity of the Black Hills in the region of the 
 upper Missouri, there are some beds of impure limestone 
 containing marine fossils which are true Jurassic. (Meek 
 and Hay den). These beds overlie the gypsiferous forma- 
 tion just mentioned. 
 
168 MESOZOIC TIME REPTILIAN AGE. 
 
 In Europe the Triassic rocks of eastern France and Ger- 
 many, east and west of the Rhine, consist of a Shell lime- 
 stone (called in German Muschelkalk) between an underlying 
 thick reddish sandstone (Bunter Sandsteiri) and overlying 
 strata of reddish and mottled marlites and sandstone (Keu- 
 per of the Germans). In England (see No. 6 on map, p. 
 120), the rock is a reddish sandstone and marlite; it is 
 mostly confined to a region running north-northwest just 
 east of the Paleozoic areas mentioned on page 163, and to 
 an extension of this region westward to Liverpool bay (or 
 over the interval between the two main areas) and up the 
 west coast. 
 
 This formation, in Europe, contains in many places beds 
 of salt, and is hence often called the Saliferous group. At 
 Northwich in Cheshire, in England, there are two beds of 
 rock-salt, 90 to 100 feet thick; and in Europe there are 
 similar beds at Yic and Dieuze in France, and at Wurtem- 
 berg in Germany. 
 
 The Jurassic rocks of Britain and Europe are divided 
 into three principal groups : 
 
 1. The Liassic (No. 7 a on map of England, p. 120), con- 
 sisting of grayish compact limestone strata, called Lias. 
 
 2. The Oolitic (No. 7 b on map, p. 120), consisting mostly 
 of whitish and grayish limestones, part of them oolitic (p. 
 25). One stratum, near the middle of the series, is a coral- 
 reef limestone, much like the reef-rock of existing coral 
 seas, though wholly diiferent in species of coral. Near the 
 top of the series there are some local beds of fresh-water or 
 terrestrial origin, in what is called the Purbeck group, and 
 one on the island of Portland is named, significantly, the 
 Portland dirt-bed. The Solenhofen lithographic limestone is 
 a very fine-grained rock (thereby fit for lithography), of 
 the age of the Middle Oolite, occurring in Pappenheim in 
 Bavaria. 
 
 3. The Wealden (No. 8 on the map of England) : a series 
 
TRIASSIC AND JURASSIC PERIODS. 
 
 167 
 
 &f beds of estuary and fresh-water origin, mostly clay and 
 Sand, but partly of limestone. They occur in southeastern 
 England. They are named Wealden from the region where 
 first studied, called the Weald, covering parts of Kent, Surrey, 
 and Sussex. 
 
 2. Life. 
 1. Plants. 
 
 The vegetation of the Triassic and Jurassic periods 
 included numerous kinds of Ferns, both large and small, 
 Calamites, and Conifers, and so far resembled that of the 
 Carboniferous age. But there were no forests or jungles 
 of Lepidodendra and Sigillarise. Instead of these Carbon- 
 iferous types, a new group of trees and shrubs existed, 
 that of the Cycads. This group was eminently character- 
 istic of the Mesozoic world : it has now but few living 
 species, and among the genera, Cycas and Zamia are those 
 whose names are best known. 
 
 mi Figs. 254, 255. 
 
 The plants have the aspect 
 of palms; and there was, 
 therefore, in the Mesozoic 
 forests a mingling of palm- 
 like foliage with that of Coni- 
 fers (spruces, cypress, and 
 the like). But the Cycads are 
 not true Palms. They are 
 Gymnosperms, like the Coni- 
 fers both in the structure of 
 the wood and in the fruit. 
 The resemblance to Palms is 
 mainly in the cluster of great 
 
 leaves at the summit, and in rig T 2 54, Leaf of a living zamia 
 the appearance of the ex- stum P of the c y cad ' Mantellia 
 
 ,* Al i -r,. nf . A dea)megalophylla(Xgt)- 
 
 tenor of the trunk. Fig. 254 
 
 represents the leaf of a modern species reduced to one- 
 twentieth the actual length; and fig. 255 the trunk of 
 
 15* 
 
168 MESOZOIC TIME REPTILIAN AGE. 
 
 a fossil species from the Portland dirt-bed, where they 
 are common. The trunks of some Cycads have a height 
 of 15 or 20 feet. Although the form of the leaf is palm- 
 like, the leaflets do not split lengthwise with facility, like 
 those of Palms. In one important respect these Cycads 
 resemble the Ferns, that is, in the unfolding of the young 
 l ea f ? the leaf being at first rolled up into a coil, and gra- 
 
 Figs. 256-260. 
 
 Fig. 256, Podozamites lanceolatus; 257, Pterophyllum graminioides ; 258, Clathroptem 
 rectiusculus ; 259, Pecopteris Stuttgartensis ; 260, Cyclopteria linnoeifolia. 
 
 dually unrolling as it expands. The Cycads thus combine 
 peculiarities of three orders of plants, Ferns, Palms, and 
 Conifers, and are examples, therefore, of what are called 
 comprehensive types. 
 
TRIASSIC AND JURASSIC PERIODS. 169 
 
 Fossil plants are common in the coal regions of Kichmond, 
 Virginia, and in North Carolina, and occur also in other 
 localities. The following figures represent some of the spe- 
 cies. Figs. 256, 257 are parts of the leaves of two species 
 of Cycads, from North Carolina. Figs. 258 to 260 repre- 
 sent a few of the ferns : fig. 258, a Clathropteris, from East 
 Hampton, Mass.; fig. 259, a Pecopteris, from Kichmond, 
 Ya., and the Trias of Europe ; fig. 260, a Cyclopteris, from 
 Richmond, Ya. Large cones of firs have also heen found. 
 Several of the American plants are identical in species with 
 those of the European Triassic, and a few nearer to Jurassic 
 forms. 
 
 2. Animals. 
 A. AMERICAN. 
 
 The American heds of the Atlantic border region are 
 remarkable for the absence of true marine life : all the species 
 appear to he either those of brackish water, or of fresh 
 water or the land. 
 
 1. Radiates and Mollusks. Radiates are unknown. There 
 are very few Mollusks of any kind, and these are Conchifers. 
 
 2. Articulates. The shells of Ostracoid Crustaceans are 
 common in Pennsylvania, Yirginia, and North Carolina, 
 but have not yet been "found in New England. Fig. 261 
 represents one of the little shells of these bivalve 
 species, called an Estheria. It was long supposed to Fig. 261. 
 be Molluscan. The Estherice are brackish-water 
 species. 
 
 A few remains of Insects have been found, and, 
 what is more remarkable, the tracks of several 
 species. These tracks were left on the soft mud probably 
 by the larves of the Insects, for certain kinds pass their 
 larval state in the water. Fig. 262 represents one of these 
 larves found in shale at Turner's Falls in Massachusetts; 
 it resembles, according to Dr. Le Conte, the larve of a 
 
 Estheria 
 ovata. 
 
170 
 
 MESOZOIC TIME REPTILIAN AGE. 
 
 Figs. 262-264. 
 
 7 
 
 ;nf 
 
 ! ''^ 
 
 ! ; 'r 
 
 M 
 
 A 
 
 A 
 
 A 
 
 64 
 
 modern Ephemera. Figs. 263, 264 are the tracks of Insects. 
 Prof. Hitchcock has named nearly 30 species of tracks of 
 Insects and Crustaceans. 
 
 Vertebrates. There are evidences of the existence of 
 Fishes, Reptiles, Birds, and 
 Mammals. The last two types 
 here make their first appear- 
 ance, and thus the sub-king- 
 dom of Vertebrates is finally 
 represented in all its classes. 
 
 The Fishes found in the 
 American rocks are all Ga- 
 noids, although Selachian re- 
 mains are common in Europe. 
 Fig. 265 represents one of the ARTICULATES ._ rig . 262> Palep hemera 
 
 , reduced One-half. seva (x |) ; 263, 264, Tracks of Insects. 
 
 
 Fig. 265. 
 
 Fig. 265, GANOID, Catoptems gracilis (X K) '> a > Scale of same, natural size. 
 
 The Eeptiles of the era are known to us partly from their 
 fossil bones and partly from their footprints. The foot- 
 prints indicate a wonderful variety as to form and size. 
 Bones have been found especially in Pennsylvania, North 
 Carolina, and Nova Scotia. Fig. 266 represents a tooth, 
 half the natural size, of a Nova Scotia species (Bothy gnaihus 
 borealis of Leidy); and fig. 267, a tooth of another, from 
 North Carolina, Palceosaurus Carolinensis Emmons. Several 
 
TRIASSIC AND JURASSIC PERIODS. 
 
 171 
 
 kinds occur at Phoenixville, Pa., where there is literally a 
 bone-bed. 
 
 Figs. 268-270 represent the tracks of three species of 
 Eeptiles from the Connecticut valley beds; 268-270 are 
 
 Figs. 266-270. 
 
 REPTILES. Fig. 266, Bathygnathus borealis (X M); 267, Palaeosaurus Carolinensis ; 267 a, 
 section of same; 268, 268 a, fore and hind feet of Anisopus Deweyanus (X /)', 269, 269 a, 
 id. of A. gracilis (X i); 270, 270 a, id. of Otozoum Moodii (X AJ)- 
 
 the impressions made by the fore-foot in each, and 268 #, 
 269 a, 270 a, of the hind-foot. Fig. 270 is reduced to one- 
 eighteenth the natural size, the actual length of the track 
 being 20 inches. The animal is called Otozoum Moodii by 
 Hitchcock : it appears to have walked like a biped, bringing 
 its fore-feet to the ground only occasionally, impressions of 
 these feet being seldom found. The animal had a stride of 
 3 feet, and must have been of formidable dimensions. One 
 slab, 30 feet long, in the collection of Amherst College 
 (Massachusetts) contains 11 tracks of this huge animal. 
 Some of the .Reptiles made three-toed tracks, closely like 
 
172 
 
 MESOZOIC TIME REPTILIAN AGE. 
 
 those of birds ; and this fact has led some to question whe- 
 ther all may not be Reptilian. 
 
 The tracks regarded as those of birds are also very nume- 
 rous. The largest of them is nearly 2 feet long (fig. 271), 
 far exceeding that of an Ostrich, and even surpassing that 
 which the giant Moa of New Zealand might have made (p. 
 
 Figs. 271, 272. 
 
 72 
 
 Fig. 271, Track of Brontozoum giganteum (X %) ; 272, Slab of sandstone with tracks of 
 Birds and Reptiles (X &) 
 
 241). Fig. 272 represents, on a small scale, a slab from the 
 Connecticut River sandstone covered with tracks of birds 
 and reptiles, as figured by Hitchcock. The two tracks 
 lettered a are added, of larger proportional size than the 
 others, to show more distinctly the form. 
 
 The only relic of a Mammal yet discovered in the Ameri- 
 can rocks is a jawbone (fig. 273). It is from North Caro- 
 lina, and is named Dromatherium sylvestre by Emmons. It 
 
TRIASSIC AND JURASSIC PERIODS. 
 
 173 
 
 Fig. 273. 
 
 belongs to the order of Marsupials, the same which con- 
 tains the modern Opossum. 
 
 The facts prove that the land-population of Mesozoic 
 America included Insects, 
 Hcptiles, Birds, and Marsu- 
 pial Mammals, and that the 
 forests that covered the hills 
 were mainly composed of 
 Conifers and Cycads. 
 
 B. FOREIGN. 
 
 The European and British rocks of these periods, espe- 
 cially of the Jurassic, abound in marine fossils, and afford a 
 
 Figs. 274-277 
 
 Jawbone of Dromatherium sylvestre. 
 
 RADIATES. rig. 274, the Coral, Prionastrsea oblonga; 275, the Crinoid, Encrinus liliiformis ; 
 276, Cidaris Blumenbachii ; 277, Spine of same. 
 
 knowledge of the Mesozoic life of the ocean which we fail 
 to get from the American records. The remains of terres- 
 trial life are also of great interest, and, like the American, 
 
174 
 
 MESOZOIC TIME REPTILIAN AGE. 
 
 they attest the existence of Birds and Mammals in the course 
 of the era. 
 
 1. Radiates. Polyp-corals are common in some Jurassic 
 strata : they are related to the modern tribe of corals, and 
 not to the ancient : none of the Paleozoic types existed. 
 Fig. 274 is one of the oolitic species. Crinoids are of many 
 kinds, yet their number, as compared with other fossils, is 
 far less than in the preceding ages ; and they are accompa- 
 nied by various new forms of Star-fishes and Echini (p. 57). 
 Fig. 275 represents one of the Triassic Crinoids, the Lily- 
 Encrinite, or Encrinus liliiformis; fig. 276, an Echinus, from 
 
 Figs. 278-281. 
 
 MOLLUSKS. Fig. 278, Spirifer Walcotti; 279, Gryphfea arcuata; 280, Trigonia clavellata; 
 281, Vivipara (Paludina) Fluviorum. 
 
 the Oolite, stripped of its spines, and fig. 277, one of the 
 spines separate. 
 
 . 2. Mollusks. Brachiopods are few compared with the 
 Paleozoic. The last species of the Paleozoic families of the 
 Spirifers and Leptcenas lived in the earlier part of the Juras- 
 sic period. Fig. 278 represents one of these last of the Spiri- 
 
TRIASS1C AND JURASSIC PERIODS. 
 
 175 
 
 fer group. Conchifers and G-asteropods abound in species, 
 and under various new, and many of them modern, genera. 
 The genus Gryphcea (fig. 279 representing a Liassic species) 
 is common in the Lias and later Mesozoic rocks : it is an 
 oyster with the beak incurved. Trigonia (fig. 280) is a cha- 
 racteristic genus of the Mesozoic. The name alludes to the 
 triangular form of the shell : the species figured is from the 
 Oolite. Fig. 281 represents a fresh-water snail-shell, a very 
 abundant fossil in fresh-water limestone of the Wealden, 
 closely resembling many modern species. 
 
 But the most remarkable and characteristic of all Mesozoic 
 Mollusks were the Cephalopoda. This order passed its maxi- 
 mum as to number and size in the Mesozoic, and hundreds 
 of species existed. The last of the Paleozoic type of Ortho- 
 
 Figs. 282, 283. 
 
 82 
 
 MOLLUSKS. Fig. 282, Ammonites Humphreysianus ; 283, A. Jason. 
 
 cerata and G-oniatites lived in the Triassic Period. In the 
 same period began the genus Ammonites, the most common 
 of the Mesozoic genera, and in the earliest Jurassic the 
 family of Belemnites, another peculiarly Mesozoic type. 
 
 16 
 
176 MESOZOIC TIME REPTILIAN AGE. 
 
 The Ammonites had external shells like the Nautili (p. 55). 
 Two Oolitic species are represented in figs. 282, 283. One 
 of them (fig. 283) has the side of the aperture very much 
 prolonged; but the margin of the shell, whether prolonged 
 or not, is seldom well preserved. The partitions (or septa) 
 within the shells of Ammonites are bent back in many folds 
 (and much plaited within each fold) at their junction with 
 the shell, so as to make deep plaited pockets. The front 
 view of the outer plate, with the entrances to its side- 
 pockets, are seen in fig. 284. The fleshy mantle of 
 the animal descended into these pockets, and thus the 
 animal was aided in holding firmly to its 
 shell. The siphuncle in the Ammonites is Fi s- 284 - 
 dorsal. The Paleozoic Croniatites were of the 
 Ammonite family, but the pockets were much 
 more simple, the flexures of the margins of 
 the partitions being without plications. 
 
 The fossil Belemnite is the internal bone of 
 a kind of Cephalopod, analogous to the pen 
 or internal bone (or osselet) of a Sepia, or Cut- 
 tle-fish (see fig. 289). It is a thick, heavy fos- 
 sil, of the forms in figs. 285, 286, having a 
 conical cavity at the upper end. The fossils 
 are more or less broken at this extremity ; 
 
 * J Ammonites tornatus. 
 
 when entire, the margin of the aperture is 
 elongated into a thin edge, and sometimes, on one side, into 
 a thin plate of the form in fig. 287. The animal had an ink- 
 bag like the modern Sepia; and ink from these ancient 
 Cephalopods has been used in sketching their fossil remains. 
 Fig. 288 represents one of the ink-bags of the Jurassic 
 Cephalopods. Fig. 289 is another related Cephalopod, show- 
 ing something of the form of the animal, and also the ink- 
 bag in place. 
 
 3. Articulates. The Articulates included various shrimps, 
 or craw-fishes (fig. 290, a Triassic species), Crabs, and Te- 
 
TRIASSIC AND JURASSIC PERIODS. 
 
 ,,. 
 
 177 
 
 tradecapod (or 14-footed) Crustaceans (fig. 291, represent- 
 ing a species something like the modern Sow-bug*), but no 
 
 Figs. 285-289. 
 
 MOLLUSKS. Fig. 285, Belemnitcs pistilliformis; 286, B. p.ixillosus ; 286 a, Outline of section 
 of same, near extremity; 287,' View, reduced, of the complete osselet of a Belemnite; 288, 
 Fossil Ink-bags of a Cephalopod ; 289, Acanthoteuthis antiquus. 
 
 Trilobites; also the first known of true Spiders (fig. 292), 
 and species of many of the orders of Insects. Fig. 293 is a 
 Libellula, or Dragon-fly, of the Jurassic period, from Solen- 
 
178 
 
 MESOZOIC TIME REPTILIAN AGE. 
 
 hofen; and fig. 294, the wing-case of a beetle, from the 
 Stonesfield Oolite. 
 
 Figs. 290-294. 
 
 ARTICULATES. Fig. 290, Pemphix Sueurii; 291, Archaeoniscus Brodiel; 292, Palpipes priscus; 
 293, Libellula ; 294, Wing-case of a Buprestis. 
 
 3. Vertebrates. The Fishes were all either Ganoids or Sela- 
 chians. In the Triassic beds occurred the last species of the 
 heterocercal Ganoids, and the first of the homocercal, along 
 with some, like fig. 265, p. 170, of intermediate character, 
 that is, having the tail-fin vertebrated through half its 
 length. Fig. 295 represents one of the homocercal Ganoids 
 of the Lias. Among the Sharks (or Selachians) the Cestra- 
 ciont tribe, the most ancient, characterized by a pavement 
 of grinding teeth (p. 52), still continued, and was very 
 numerously represented. There were also in the Jurassic 
 beds the first of the sharp-edged Shark-teeth, or those of 
 the tribe of Sharks that inhabits modern waters. 
 
 Reptiles were the dominant race in the Eeptilian world, 
 and among them were Amphibians, the division most com- 
 mon in the Carboniferous age, and also great numbers of 
 
TRIASSIC AND JURASSIC PERIODS. 
 
 179 
 
 true Eeptiles. They included species for each of the ele- 
 ments, the water, the earth, and the air. 
 
 In the Triassic the Amphibian division (p. 50) appears 
 
 Fig. 295. 
 
 VERTEBRATE. Fig. 295, Restored figure of JSchmodus (Tetragonolepis) (X %); 295 a, Scales 
 
 of same. 
 
 to have reached its maximum. One of the frog-like Laby- 
 rinthodonts had a skull of the form shown in fig. 296, whose 
 
 Figs. 296-298. 
 
 VERTEBRATES. Fig. 296, Skull of Mastodonsaurus Jsegeri (X i\); 297, Tooth of same (X /^)? 
 298, Footprints of Cheriotherium (X &). 
 
 length was 3 to 4 feet ; its mouth was set around with teeth 
 3 inches long (fig. 297), and the body was covered with 
 scales. The specimen figured was found in Saxony. It is 
 
 16* 
 
180 
 
 MESOZOIC TIME REPTILIAN AGE. 
 
 probable that some of the American Reptilian species 
 whose tracks are so common in the Connecticut valley 
 were of this type. Fig. 298 is a reduced view of hand- 
 like tracks, from the same locality as the above, sup- 
 posed to have been made by an animal of the same species. 
 The frogs of the present day are feeble and diminutive com- 
 pared with the Triassic Amphibians. 
 
 Swimming Beptiles, or Saurians, called Enaliosaurs 
 because of their living in the sea (from the Greek enalios, 
 marine, and sauros, lizard), probably existed in the Carbon- 
 iferous age (p. 135) : they became numerous and of great size 
 in the Mesozoic. They had paddles like Whales, and thus 
 
 Figs. 299-304. 
 
 VERTEBRATES. Fig. 299, Ichthyosaurus communis (XiJo); 300 Head of same (X &); 301 a, 
 301 6, View and section of vertebra of game (X %); 302, Tooth of same, natural size; 303, 
 Plesiosaurus dolichodeirus (X&); 304 a, 304 6, View and section of vertebra of same. 
 
 were well fitted for marine life. The most common kinds 
 were the Ichthyosaurs and Plesiosaurs. 
 
TRIASSIC AND JURASSIC PERIODS. 181 
 
 The Ichthyosaurs (fig. 299) had a short neck, a long and 
 large head, enormous eyes, and thin, fish-like, or doubly- 
 concave, vertebrae. The name is from the Greek ichthus, fish, 
 and saur. Fig. 300 represents the head of an Ichthyosaur, 
 one-thirtieth the natural length, showing the large size of the 
 eye and the great number of the teeth. Fig. 801 b is one 
 of the vertebrae, reduced, and fig. 301 a, a transverse section 
 of the same, exhibiting the fact that both surfaces are deeply 
 concave, nearly as in fishes; fig. 302 is one of the teeth, natu- 
 ral size. Some of the Ichthyosaurs were 30 feet long. 
 
 The Plesiosaurs (named from the Greek plesios, near, and 
 saur, because not quite like a Saurian), one of which is 
 represented very much reduced in fig. 303, had a long snake- 
 like neck, a comparatively short body, and a small head. 
 Fig. 304 a represents one of the vertebrae, and 304 b, a sec- 
 tion of the same; it is doubly-concave, but less so, and much 
 thicker, than in the Ichthyosaurs. Some species of Plesio- 
 saur were 25 to 30 feet long. Another related Reptile, called 
 a Pliosaur, was 30 to 40 feet long. Remains of more than 
 50 species of Enaliosaurs have been found in the Jurassic 
 rocks. 
 
 Besides these swimming Saurians, there were numerous 
 species of Lacertians (Lizards} and Crocodilians 10 to 50 
 feet long, and Dinosaurs, the bulkiest and highest in rank 
 of the Saurians, 25 to 60 feet long. 
 
 To the group of Dinosaurs belongs the Iguanodon, of the 
 Wealden beds, first made known by Dr. Mantell, whose body 
 was 28 to 30 feet long, and which stood high above the 
 ground quadruped-like, the femur, or thigh-bone, alone 
 being nearly 3 feet long. Its habits are supposed to have 
 been like those of a Hippopotamus, the animal grazing 
 on the plants and shrubs of the marshes, estuaries, or 
 streams in or about which it lived. It had teeth like the 
 modern Iguana (and hence the name, from Iguana, and iho 
 Greek odous, tooth), but it had proportionally a much shorter 
 
182 MESOZOIC TIME REPTILIAN AGE. 
 
 tail. The Megalosaur was another of the gigantic Dinosaurs 
 of the later part of the Jurassic period; it was a terrestrial 
 carnivorous Saurian, about 30 feet in length. 
 
 The Eeptiles adapted for the air that is, for flying are 
 designated Pterosaurs, from the Greek pteron, a wing, and 
 saur. The most common genus is called Pterodactylus. The 
 general form of a Pterodactyl is shown in fig. 305. The bone 
 of one of the fingers is greatly elongated, for the purpose of 
 
 Fig. 305. 
 
 VERTEBRATE. Pterodactylus crassirostris (X /) 
 
 supporting an expanded membrane, so as to make it serve 
 (like an analogous arrangement in bats) for flying. The 
 name Pterodactyl is from the Greek pteron, wing, and dak- 
 tulos, finger. The Pterodactyls were mostly small, and proba- 
 bly had the habits of bats ; the largest had a spread of wing 
 of about 10 feet. Unlike birds, they had a mouth full of 
 teeth, and no feathers. As Bats are flying Mammals, so the 
 Pterosaurs are simply flying Eeptiles, and have no resem- 
 blance to birds in structure, except that their bones are 
 hollow. 
 
TRIASSIC AND JURASSIC PERIODS. 
 
 183 
 
 Besides the kinds of Reptiles already mentioned, there 
 were Turtles in the Jurassic period; but, according to pre- 
 sent knowledge, the world contained no Snakes. 
 
 Coprolites (or fossil excrements) of both Reptiles and 
 Fishes are common in the bone-beds. When cut and 
 polished they have a degree of beauty sufficient to have 
 made them formerly an object of some value in jewelry. 
 
 Remains of Birds have been found in the quarries of 
 Solenhofen (p. 166). They have revealed the fact that some 
 at least of the Mesozoic species (and of America, beyond 
 question, as well as Europe) were reptilian in some of their 
 characters. The skeleton found shows that the Birds had 
 long reptile-like tails consisting of many vertebrae, and 
 finger-like claws on the fore limb or wing, like those of the 
 Pterodactyl and Bat, fitting them evidently for clinging. 
 But, while thus reptilian in some points of structure, they 
 were actually Birds, being feathered animals, and having 
 the expanse of the wing made, not by an expanded mem- 
 brane as in the Pterodactyl, but by long quill-feathers. 
 
 Figs. 306, 307. 
 
 VERTEBRATES. Fig. 306, Amphitherium Broderipii (X 2); 307, Phascolotherium Bucklandi 
 
 (X2). 
 
 The tail-quills were arranged in a row either side of the 
 long tail. The feet were precisely like those of birds. 
 
184 MESOZOIC TIME REPTILIAN AGE. 
 
 Eemairis of Mammals occur in the Upper Trias (or base 
 of the Lias) of Germany, in the Lower Oolite deposit at 
 Stonesfield, England, and in the Portland " dirt-bed" of the 
 Upper Oolite (p. 166). Nearly 20 species have been made 
 out, 14 of them from relics in the Portland " dirt-bed." The 
 larger part are Marsupials; a few are pronounced to be non- 
 marsupial Mammals of the order of Insectivores. Figs. 306, 
 307 represent the jaws of two species from Stonesfield, mag- 
 nified twice the natural size. 
 
 As Marsupials are semi-oviparous Mammals, and therefore 
 are intermediate between ordinary Mammals and the inferior 
 and oviparous Vertebrates (p. 50), it follows that both the 
 Birds and Mammals of the Mesozoic were in part, at least, 
 comprehensive or intermediate types, and partook of reptilian 
 features in the Eeptilian age. 
 
 3. General Observations. 
 
 1. American Geography. The Mesozoic sandstones and 
 shales of the Atlantic border region are sedimentary beds ; 
 consequently, the long narrow ranges of country in which 
 they were formed were occupied at the time more or less 
 completely by water. 
 
 The absence of true marine fossils has been remarked 
 upon as proving that this water was either brackish or 
 fresh; and hence the areas were estuaries or deep bays 
 running far into the land. 
 
 There was probably an abundance of marine life in the 
 ocean, if we may judge from its diversity on the other side 
 of the Atlantic ; but the seacoast of the era must have been 
 outside of the present one, so that any true marine or sea- 
 coast deposits that were made are now submerged. The 
 present sea-border is shallow for a distance of 80 miles from 
 the New Jersey coast, the depth of water at this distance 
 out being but 600 feet. 
 
TRIASSIC AND JURASSIC PERIODS. 185 
 
 As all the depressions or valleys occupied by the estuaries 
 are parallel with the Appalachians (p. 164), and since the 
 era of the formations was that next following the origin of 
 these mountains, the depressions must have been made at 
 the time the Appalachian foldings were in progress. In fact, 
 they are some of the great valleys or depressions left in the 
 course of the upliftings. 
 
 The level of the several sandstone areas above the ocean 
 proves that the land at the time was not far from its present 
 elevation, and therefore that the Appalachians had probably 
 nearly their present height. 
 
 The deposits contain foot-prints, ripple-marks, rain-drop 
 impressions, and other evidences, on many of the layers, 
 that they were formed partly in shallow waters, and partly 
 as sand-flats, or emerging marshes and shores, over which 
 reptiles and birds might have walked or waded. If, then, 
 they are several thousands of feet thick, there must have 
 been a progressing subsidence of the valley-depressions 
 that is, a sinking must have been going on. It is hence 
 apparent that the oscillations of level that characterized 
 the epoch of the Appalachian revolution were still in pro- 
 gress. Two effects of this subsidence occurred : (1) The 
 sandstone beds were more or less faulted and tilted, those 
 of the Connecticut valley receiving a dip to the eastward, 
 those of 'New Jersey and Pennsylvania to the northwest- 
 ward. (2) In the sinking of the valley-depression, an 
 increasing strain was produced in the earth's crystalline 
 crust beneath, which finally became so great that the crust 
 broke, fissures opened, and liquid rock came up. The dikes 
 and ridges of trap are this liquid rock solidified by cooling. 
 The existence of the dikes, and their parallelism to the 
 general course of the valley-depressions, prove (1) the fact 
 of the fractures; (2) their resulting from the same cause 
 which produced the sinking; and (3) the fact of the igneous 
 ejections. The earth's crust along the Connecticut valley 
 
186 MESOZOIC TIME REPTILIAN AGE. 
 
 was thus a scene of igneous operations for a length over 100 
 miles, and through a vast number of opened fissures. The 
 Palisades of the Hudson date from the same period, pro- 
 bably the middle of the Jurassic period. 
 
 The Western Interior, or Rocky Mountain region, had been 
 mostly submerged during the Carboniferous age, as shown 
 by the fact that limestones were forming there in the Coal 
 Measure period, and fossiliferous sandstones in the Permian. 
 The Gypsiferous sandstone of the Mesozoic proves, by its 
 nature, its gypsum, and its rare fossils, that, by some change, 
 this great region had become mostly an interior shallow salt 
 sea, shut off to a great extent from the ocean. Such a sea 
 would have been made too fresh for marine life in the rainy 
 season, and probably too salt for any life in the hot season. 
 Hence, as in the Great Salt Lake of Utah, life would have 
 been absent. The salt waters by evaporation would have 
 furnished gypsum to the beds, as happens now sometimes 
 from sea- water. It follows, then, from the beds of the 
 Atlantic border as well as those of the Western Interior, 
 that the continent during the era of these Mesozoic beds 
 was to a less extent submerged than in the greater part 
 of the Paleozoic ages and the following portion of the 
 Mesozoic. The fossiliferous Jurassic beds mentioned on 
 page 165 show that before the Jurassic period had closed, 
 the sea had again free access over it; and the later Cre- 
 taceous formations prove that in the Cretaceous period 
 also this marine condition prevailed. 
 
 2. Foreign Geography. The nature of the Triassic beds 
 of Britain and Europe show that there were large shallow 
 interior seas also on the eastern side of the Atlantic. The 
 salt-deposits in the beds, the paucity of fossils in the most 
 of the strata, and the prevalence of marlites, indicate the 
 same conditions as existed in New York during the forma- 
 tion of the Saliferous beds of the Upper Silurian (see page 
 95), arid somewhat similar to those in which the Rocky 
 
TRIASSIC AND JURASSIC PERIODS. 187 
 
 Mountain Gypsiferous formation originated. The limestone 
 that intervened along the Khine, between the two forma- 
 tions of sandstone and marlites, shows an interval of more 
 open sea; yet the impurity of the limestone suggests that 
 the ocean had not full sweep over the region. 
 
 The beds of the Jurassic period are almost all of them 
 evidence, both from their constitution and their abundant 
 marine life, that the free ocean again had sway over large 
 portions of the Continental area. Its limits, however, 
 became more contracted as the period passed, and towards 
 its close fresh-water and terrestrial beds were forming in 
 some places that had earlier in the period been under saty 
 water. 
 
 3. Climate. The Jurassic coral reefs of Britain indicate 
 that England then lay within the sub-tropical oceanic zone. 
 
 This zone now has the parallel of 27 to 28 as, in general, 
 its outer limit (lying mostly between 20 and 27); and, con- 
 sequently, its Jurassic limit, if including England, reached 
 twice as far towards the pole as now. It is possible, how- 
 ever, that the line ran along the British Channel, and that 
 the Gulf Stream of the era carried the sub-tropical tempera- 
 ture northeastward through the British seas, as it now 
 does to Bermuda, in latitude 34. 
 
 The following are other facts of similar import. In Arctic 
 America, species of shells allied to those of Europe and 
 tropical South America occur in latitudes 60 to 77 16'; 
 and one species of Belemnite and one of Ammonite are said to 
 be identical with species occurring in these two remote and 
 now widely different regions. If not absolutely identical, 
 the evidence from them as to oceanic temperature is nearly 
 the same. Moreover, on Exmouth Island, in 77 16' N., 
 remains of an Ichthyosaur have been found, and in 76 22' N., 
 on Bathurst Island, bones of other large Jurassic Reptiles 
 (Teleosaurs'). It is probable, therefore, that a warm-tempe- 
 rate oceanic zone covered the Arctic to the parallel of 78, 
 
 17 
 
188 MESOZOIC TIME REPTILIAN AGE 
 
 if not beyond. No large living reptiles exist outside of the 
 warm-temperate zone. 
 
 2. CRETACEOUS PERIOD. 
 
 General characteristics. The Cretaceous, while the closing 
 period of Mesozoic time, was also, in some respects, a 
 transition period between the Mesozoic and Cenozoic. 
 During its progress, as is explained beyond, occurred the 
 decline, and, at its close, the extinction, of a large number 
 of the tribes of the medieval world, while, at the same time, 
 there appeared in its course other tribes eminently charac- 
 teristic of the modern world. Among these modernizing 
 features, the most prominent arose from the introduction of 
 Palms and Angiosperms among plants, and Teliosts among 
 fishes. 
 
 The Palms and Angiosperms include nearly all the fruit- 
 trees of the world, and constitute far the larger part of 
 modern forests. The Conifers and Cycads, wherever they 
 now occur near groves of Angiosperms, exhibit the contrast 
 between the medieval foliage and that of the present age. 
 The Teliosts (p. 50) embrace nearly all modern fishes 
 excepting those of the order of Sharks, or Selachians. 
 Their appearance was as great a change for the waters as 
 the new tribes of plants for the land. These tribes of plants 
 and fishes were only begun in the Cretaceous; their full 
 exhibition belongs to Cenozoic time and the Age of Man. 
 
 1, Hocks: kinds and distribution. 
 
 In North America, the Cretaceous formation borders the 
 continent on the Atlantic side, eouth of New York, and 
 along the north and west sides of the Gulf of Mexico; 
 besides, it spreads from Texas, northward, over the slopes 
 of the Eocky Mountains, being now at a height in some 
 places of 6000 to 7000 feet above the sea. Its beds are 
 exposed to view in New Jersey and in some portions of the 
 
CRETACEOUS PERIOD. 189 
 
 more southern Atlantic States, though mostly covered by 
 the Tertiary. They are largely displayed through Alabama 
 and Mississippi, and cover a great area west of the Missis- 
 sippi. (See map, p. 69). 
 
 In England the formation occupies a region just east of 
 the Jurassic, stretching from Dorset on the British Channel 
 eastward, and also northeastward to Norfolk on the German 
 Ocean, and continuing near the borders of this ocean, still 
 farther north, beyond Flamborough Head : it is numbered 9 
 on the map, p. 120. Cretaceous rocks occur, also in northern 
 and southern France, and many other parts of Europe. 
 
 Among the rocks there are the following kinds : the soft 
 variety of limestone called Chalk; hard limestones; ordi- 
 nary hard sandstones ; shales and conglomerates like those 
 of other ages; but, more common than these, soft sand- 
 beds, clay-beds, and shell-beds, so imperfectly consolidated 
 that they may be turned up with a pick. 
 
 Many of the sand-beds or sandstones have a dark-green 
 color, and are called green-sand. The green color is owing 
 to the presence of dark-green grains which occur mixed 
 with more or less of common sand. They are a hydrous 
 silicate of iron and potash. This green-sand is often used 
 for fertilizing land, and when so used it is called marl. 
 
 Chalk-beds are the source of flint. The flint is distributed 
 through the chalk in layers, these layers being made up of 
 nodules of flint, or masses of irregular forms. Although 
 often of rounded forms, they are not water-worn stones of 
 foreign origin, but were formed in place, like the hornstone 
 in the Corniferous limestone of New York (p. 105). 
 
 Chalk constitutes a large proportion of the Cretaceous 
 formation in England and some parts of Europe, but is not 
 known in the American Cretaceous. The succession of beds 
 in England is as follows : (1) The Lower Cretaceous, con- 
 sisting largely of the Green-sand and other arenaceous 
 beds, called collectively the Lower Green-sand; (2) the 
 
190 MESOZOIC TIME REPTILIAN AGE. 
 
 Middle Cretaceous, containing the Upper Green-sand and 
 some other beds ; (3) the Upper Cretaceous, comprising the 
 Chalk-beds, the lower part of which is without flints. 
 
 The Cretaceous beds in North America are supposed to 
 correspond to the Middle and Upper of the European Cre- 
 taceous. They consist of layers of Green-sand, thick sand- 
 beds of other kinds, clays, shell-beds, and, in some places in 
 the States bordering on the Mexican Gulf (especially in 
 Texas), limestone. The thickness of the formation in New 
 Jersey is 400 to 500 feet; in Alabama, 500 to 600 feet; in 
 Texas, about 800, nearly all of it compact limestone ; in the 
 region of the Upper Missouri, 2000 to 2500 feet. 
 
 2. Life. 
 1. Plants. 
 
 The first of Angiosperms and of Palms, as already stated, 
 date from the Cretaceous period. Leaves of a few Ameri- 
 can species of the former are represented in figs. 308-311 ; 
 fig. 309, from a species of Sassafras; fig. 310, a Liriodendron ; 
 and fig. 311, a Willow; and with these occur leaves of Oak, 
 Dogwood, Beech, Poplar, &c. 
 
 Besides these highest of plants, there were also Conifers, 
 Ferns, and Sea-weeds, as in former time, with some Cycads 
 still. The microscopic Algae called Diatoms (p. 61), which 
 make siliceous shells, and others called Desmids (p. 61), 
 which consist of one or a few simple green cellules, were 
 very abundant. Both occur fossil in flint; and a species of 
 the latter is very similar to one from the Devonian horn- 
 stone figured on page 109 (fig. 180). The Diatoms are believed 
 to have contributed part of the silica of which the flint is 
 formed. 
 
 2. Animals. 
 
 1. Protozoans. The simplest of animals, Rhizopods, of the 
 group of Protozoans (p. 59), were of great geological im- 
 portance in the Cretaceous period; for the Chalk is supposed 
 
CRETACEOUS PERIOD. 
 
 191 
 
 to be made mostly from their minute calcareous shells. The 
 
 powdered chalk is often found to contain large numbers of 
 
 Figs. 308-311. 
 
 Fig. 308, Leguminosites Marcouanus ; 309, Sassafras Cretaceum ; 310, Liriodendron Meekii ; 
 311, Salix Meekii. 
 
 these shells, the great majority of which do not exceed a 
 pin's head in size. A few of the forms are represented in 
 
 Figs. 312-316. 
 12 13 U 15 
 
 RHIZOPODS: Fig. 312, Lituola naxitiloidea ; 313, Flabellina rugosa; 314, Chrysalidina gradata 
 
 315, Cuneolina pavonia ; 316, Orbitolina Texana. 
 
 17* 
 
192 
 
 MESOZOIC TIME REPTILIAN AGE. 
 
 Fig. 317. 
 
 figs. 312 to 316, all very much enlarged, except 316, which is 
 natural size. A very common kind resembles fig. 99, p. 
 59, and is called a Rotalia. Fig. 316 represents a large 
 disk-shaped species, called an Orbitolina, from Texas. 
 
 Besides the above Protozoans, Sponges were also very 
 abundant, and their siliceous spicula (p. 58) were another 
 important source of the silica of the 
 flints. Fig. 317 represents one of the 
 Sponges from the Chalk of Europe. 
 
 2. Radiates Mollusks. Corals 
 and Echini were common among 
 Eadiates. Mollusks abounded, both 
 of the Ammonite and Belemnite 
 types, besides others of genera not 
 peculiar to the Mesozoic. Many of 
 the genera are identical with those 
 represented in modern seas. 
 
 Figs. 318-321. 
 
 Siphonia lobata. 
 
 MOLLUSKS : Fig. 318, Exogyra costata ; 319, Inoceramus probleinaticus ; 
 lam; 321, G. Pitcheri. 
 
 , Gryphsea vesicu- 
 
CRETACEOUS PERIOD. 
 
 Figs. 322-328. 
 
 26 
 
 193 
 
 MOLLUSKS : Fig. 322, Fasciolaria buccinoides ; 323, Fusus Newberryi ; 324, Ammonites Pla- 
 centa; 324 a, id., in profile, reduced; 325, Scaphites lameformis ; 326, Turrilites catenatus; 
 327, Baculites ovatus ; 328, Belemnitella mucronata. 
 
194 MESOZOIC TIME REPTILIAN AGE. 
 
 Figs. 318-321 are of some of the most characteristic Con- 
 chifers from the American Cretaceous; fig. 318, an Exogyra; 
 fig. 319, an Inoceramus; figs. 320, 321, Gryphceas : genera that 
 are now extinct. Figs. 322,323 represent shells of Gastero- 
 pods, and 324 to 328, Cephalopods, all American except 
 326; fig. 324, an upper front view of an Ammonite, showing the 
 pockets along the sides of one of the partitions ; fig. 324 a, 
 a reduced view of the same Ammonite in profile ; figs. 325 
 to 327, three species of the Ammonite family, but not of the 
 genus Ammonites, one, fig. 325, being called a Scaphites 
 (from the Latin scapha, a skiff), an Ammonite with the shell 
 looking as if partly uncoiled, and thus made somewhat to 
 resemble a boat; fig. 326, a Turrilites, or turreted Ammonite, 
 an anomaly in the family, as the species are almost all 
 coiled in a flat plane; fig. 327, a Baculites, or straight Ammon- 
 ite, so named from the Latin baculum, a walking-stick. 
 Fig. 328 represents a very common New Jersey species of 
 Belemnites. Some of the Ammonites of the Cretaceous 
 period are 3 to 4 feet in diameter. 
 
 3. Vertebrates. Among Vertebrates appeared the first of 
 
 Osmeroides Lewesiensis (X /<) 
 
 the Teliost or Osseous Fishes, fishes allied to the perch, 
 salmon, pickerel, etc. They occur along with numerous 
 Sharks of both ancient and modern types (Cestracionts and 
 
CRETACEOUS PERIOD. 
 
 195 
 
 Squalodonts), and many also of Ganoids. Thus the ancient 
 and modern forms of Fishes were united in the population 
 of the Cretaceous seas, the former, however, making hardly 
 more than a tenth of the species. Fig. 829 represents one 
 of these Teliost Fishes, related to the Salmon and Smelt, from 
 the Chalk at Lewes, England. There were also Herring, 
 and many other kinds. 
 
 The Reptiles included species of some of the Jurassic 
 genera, as Pterodactyls, Ichthyosaurs, Plesiosaurs, and the 
 
 Fig. 330. 
 
 Mosasaurus Hofmanni (X ^)- 
 
 Iguanodon; also of other genera, as Mosasaurs (fig. 330), and 
 true Crocodiles. 
 
 No remains of Mammals or Birds have yet been gathered 
 from the Cretaceous formation. 
 
 3, General Observations. 
 
 1. Geography. In North America the position of the 
 Cretaceous beds along the borders of the Atlantic south of 
 New York, near the Mexican Gulf, and also over a large part 
 of the Eocky Mountain region, indicates that these border 
 
196 MESOZOIC TIME REPTILIAN AGE. 
 
 regions and the Western Interior were under water when 
 the period opened, as represented in the following map (fig. 
 331). The shaded part of the continent exhibits the extent 
 to which it was submerged. (This map should be compared 
 with that on page 73). It shows that the Chesapeake and 
 Delaware Gulfs were in the ocean ; that Florida was still under 
 water; that the region of the Missouri River was a salt- 
 Fig. 331. 
 
 North America in the Cretaceous Period ; MO, Upper Missouri region. 
 
 water region; that in fact the Kocky Mountains were at 
 least 6000 or 7000 feet lower than now, the Cretaceous beds 
 having now this elevation upon them. The Mexican Gulf 
 spread over a large part of Georgia, Alabama, and Missis- 
 sippi, extended northward to the mou-th of the Ohio, and 
 
CRETACEOUS PERIOD. 197 
 
 then west of Missouri and Kansas stretched far north over 
 the present slopes of the great Western mountains, reaching 
 perhaps to the Arctic, though on this point the evidence is 
 not yet decisive. The deposits, excepting those of Texas, 
 appear to be of seashore and off-shore formations; the 
 Texan compact limestones were probably formed in clear 
 interior waters. 
 
 In Europe the Chalk appears to have been accumulated 
 in an open sea, where the water was one or more hundred 
 feet deep. The material of the Chalk has been stated on 
 page 190 to be mainly the shells of Rhizopods, and that of 
 the associated flint to have been derived from Diatoms and 
 Sponges. Rhizopods and Diatoms are now living in many 
 parts of the ocean, over the bottom, even where the depth 
 is thousands of feet, and are making accumulations of vast 
 area. There appear, hence, to be in the present seas the 
 conditions requisite for making chalk and also flint. The- 
 many Sponges, Echini, and Shells found in the Chalk beds 
 are evidence, however, that tha%depth was not thousands of 
 feet, although it may have been a few hundreds. The fossils 
 of the Chalk are in many regions turned into flint, and some 
 hollow specimens are filled with quartz-crystals, or agate 
 
 2. Climate. The corals and other tropical life of the Bri- 
 tish rocks indicate that the seas were at least warm-tem- 
 perate to latitude 60 north on the east side of the ocean. 
 On the American side it appears to have been cooler, as it 
 now is, in corresponding latitudes; and still the temperature 
 was considerably warmer than the present. The warm 
 oceanic zone which spread over the British seas appears, 
 from the distribution of the fossils, to have reached the 
 North American coast south of Long Island, and perhaps 
 had no place on the coast north of Cape Hatteras. The 
 plants of the Upper Missouri region indicate a warm-tem- 
 perate climate over that territory. 
 
198 MESOZOIC TIME. 
 
 GENERAL OBSERVATIONS ON THE MESOZOIC. 
 
 1. Time-Ratios. The ratios between the Paleozoic ages as 
 to the length of time that elapsed during their progress, or 
 their time-ratios, are stated on p. 145 as probably not far 
 from 3:1:1. 
 
 The American Mesozoic formations are too imperfect to 
 be used as data for calculating the Mesozoic time-ratios; and 
 in Europe there is much uncertainty as to the actual thick- 
 ness of the rocks. Calculating from the best estimates of 
 the thickness which have been given, the time-ratio between 
 the Paleozoic and Mesozoic is nearly 3:1; and between 
 the Triassic, Jurassic, and Cretaceous periods, 1 : li : 1. 
 That is, Mesozoic time was hardly one-third as long as the 
 Paleozoic ; and the three periods of the Mesozoic were not 
 far from equal, the Jurassic being one-quarter the longest. 
 
 2. American Geography. On page 162 it is remarked that 
 the Mesozoic formations were confined to the Atlantic and 
 Gulf border regions, and to. an interior region west of the 
 Mississippi covering much of the Rocky Mountain area, and 
 that the intermediate portion of the continent had probably 
 become part of the dry land. The facts which have been 
 presented in the preceding pages have sustained this state- 
 ment. The Triassico-Jurassic beds, as has been shown, 
 lie in long narrow strips between the Appalachians and the 
 coast, and spread widely over the Rocky Mountain region. 
 The Cretaceous beds cover the Atlantic and Gulf borders, 
 and also, like the Triassic, a very large part of the slopes 
 of the Rocky Mountains. The eastern half of the continent 
 during the Mesozoic was, therefore, receiving rock-forma- 
 tions only along its borders, while the western half had 
 marine deposits in progress over its great interior. None 
 of the American Mesozoic deposits bear any evidence that 
 they were formed in a deep ocean. They appear to have 
 been formed along coasts, or in shallow waters off coasts, or 
 
REPTILIAN AGE. 199 
 
 in shallow inland seas; and only the Cretaceous limestone 
 of Texas indicates a pure open, though not deep, sea, like 
 that required for coral-reefs. 
 
 The Appalachians the eastern mountains of the continent 
 had nearly their present elevation before the early Meso- 
 zoic beds commenced to form (p. 185). But the region of 
 the Eocky Mountains the western chain was to a great 
 extent still a shallow sea even during the Cretaceous period, 
 or when the Mesozoic era was drawing to its close (p. 197). 
 
 Only one series of mountain-elevations can be pointed 
 out, with our present knowledge, as originating in eastern 
 North America in the course of the Mesozoic era, although 
 great oscillations of level were much of the time in progress 
 (p. 185). This one is that of the Mesozoic red sandstone 
 and trap along the Atlantic border region. The trap ridges, 
 ranging through the Connecticut valley from New Haven, 
 Ct., to northern Massachusetts, that of the Palisades on the 
 Hudson, and those connected with the early Mesozoic rocks 
 of New Jersey, Pennsylvania, Virginia, North Carolina, 
 and Nova Scotia, appear to date from a common epoch 
 (p. 185). They conform to a common system, being parallel 
 to the Appalachian chain through its varying courses, and 
 not following one special compass-course. The epoch of 
 their formation probably divides off the Triassico- Jurassic ^ 
 period of North Americ'a from the Cretaceous. 
 
 The study of the Pacific border of the continent will 
 probably make known one or more additional mountain- 
 ranges of Mesozoic origin. 
 
 3. European Geography. Europe has its Mesozoic rocks 
 distributed in patches, or in several independent or nearly 
 independent areas, which show that it retained its condition 
 of an archipelago throughout Mesozoic time. The oscilla- 
 tions of level, as indicated by the variations in the rocks, 
 variations both as to the nature of the beds and their distri- 
 bution, were more numerous and irregular than in North 
 
 18 
 
200 MESOZOIC TIME. 
 
 America. The mountain-elevations formed, however, were 
 few and small compared with those that followed either the 
 Paleozoic or Mesozoic era. One series of disturbances is 
 referred to the close of the Triassic, and another to the close 
 of the Jurassic. * 
 
 Among the Mesozoic formations of the European conti- 
 nent there are deposits of all kinds, those of seashores; of 
 off-shore shallow waters; of inland seas; of moderately deep 
 oceanic waters; and of marshy, or dry a-nd forest-covered, 
 land. 
 
 Both in America and Europe there .were some coal-beds 
 made, though of small extent compared., with those of the 
 Carboniferous age * * ^ 
 
 4. Life. The Mesozoic era. witnessed- 1 (1) the decline of 
 some ancient, or Paleozoic, types, of both plants and animals, 
 (2) the increase and culmination of medieval or Mesozoic 
 types, and (3) the beginning of je of the most important 
 of modern or Cenozoic types. 
 
 (1.) Disappearance of Ancient or Paleozoic features. Among 
 the ancient tribes of plants the Calamites,or tree-rushes, and 
 several genera of Ferns, disappear^in the Jurassic. Among 
 the old Brachiopod tribes ^he Spirifer and Leptcena families 
 end in the Triassic ; and among higher Mollusks the Silu- 
 rian type of Orthoccras^ and Devonian of Goniatites, have 
 their last species in tlj Triassic. 
 
 (2.) Progress in Mesozoic features. The Cycads, among 
 plants, were those nTost characteristic of the Mesozoic : they 
 afterwards yield to other kinds, and are now nearly an 
 extinct tribe. The Cephalopods,, among Mollusks, existed, 
 in vast numbers, both those with external shells, as the 
 Ammonites, and those without, as the Belemnites. The,whole 
 number of species of Cephalopods now known from the 
 Mesozoic formations is nearly 1200. Of these, about 950 
 were of the Nautilus and Ammonite families. Since the 
 Cretaceous period no Ammonite has existed, and at the 
 
REPTILIAN AGE. 201 
 
 present time there are only 2 or 3 species of Nautilus. The 
 whole number of species of Cephalopods living in the course 
 of the Mesozoic era may have been three or four times 1200, 
 as only a part would have been preserved as fossils. The sub- 
 kingdom of Mollusks, therefore, culminated in the Mesozoic 
 era; for its highest order, that of the Cephalopods, was then 
 at its maximum. 
 
 The type of Eeptiles was another that expanded and 
 reached its height that is, its maximum in number, variety, 
 and rank of species and commenced its decline in the 
 Mesozoic era. 
 
 There were huge swimming Saurians, Enaliosaurs, in the 
 place of whales in the sea; -bat-like Saurians or Pterodac- 
 tyls flying through the air; and four-footed Saurians, both 
 grazing and carnivorous, many of them 25 to 50 feet long, 
 occupying the marshes and estuaries. In the era of the 
 Wealden and Lower Cretaceous there lived, in and about 
 Great Britain, 4 or 5 species of Dinosaurs 20 to 50 feet long, 
 10 to 12 Crocodilians, Lizards, and Enaliosaurs 10 to 50 or 
 60 feet long, besides Pterodactyls and Turtles; and many 
 more than this, since all "that lived would not have left their 
 remains in the deposits. To appreciate this peculiarity of 
 medieval time, it should be considered that in the present 
 age Britain has no large Eeptiles; in Asia there are only 
 two species over 15 feet in length; in Africa but one; in all 
 America but three; in the whole world not more than six; 
 and the largest of the six does not exceed 25 feet in length. 
 The Mesozoic era is well named the Age of Reptiles. 
 
 All the Mesozoic animals, excepting the Mammals, belong 
 to the Oviparous divisions; and the Mammals were mainly 
 Marsupial species, that is, semi-oviparous Mammals, as 
 explained on p. 50, species quite in harmony, therefore, 
 with the other life of the era. The Birds of the age, or at 
 least some of them, partook of the reptilian features of the 
 time, having long tails like the associated Eeptiles (though 
 
202 MESOZOIC TIME. 
 
 feathered tails), and possessing some other peculiarities of 
 the scaly tribes. The long-tailed birds and Pterodactyls 
 were the flying creatures of the age; the Ichthyosaurs 
 and Plesiosaurs, and the like, the "great whales;" the 
 Teleosaurs, Iguanodon, and other gigantic species of the 
 estuaries and marshes, the creeping species. These, along 
 with the small Marsupials and Insectivores of the Cycadean 
 and Coniferous forests, were the more prominent kinds of 
 Mesozoic life. 
 
 (3.) Introduction of Cenozoic features. Among Plants the 
 first of AngiospermSj (or the order including all trees having 
 a bark (Oak, Maple, Apple, &c.), excepting the Conifers) and 
 the first of Palms, are found in the Cretaceous. These 
 become the characteristic plants of the Cenozoic era and 
 Age of Man. 
 
 Among Vertebrates there were the first of the great order 
 of Teliost or Osseous Fishes in the Cretaceous (p. 194), all 
 previous species being either Selachians (Shark tribe) or 
 Ganoids; the first of the modern tribe of Sharks in the 
 Jurassic ; the first of the modern genus of Crocodilus in the 
 Jurassic; the first of Birds in the Triassic or Jurassic, the 
 reptilian Birds; the first of Mammals in the Triassic, 
 Marsupials, or semi-oviparous Mammals, along with some 
 Insectivores. 
 
 Of the classes of Yertebrates, Fishes and Reptiles com- 
 mence in the middle and later Paleozoic, and Birds and 
 Mammals in the early or middle Mesozoic. 
 
 DISTURBANCES AND CHANGES OF LEVEL CLOSING MESOZOIC 
 
 TIME. 
 
 At the close of the last period of the Mesozoic era the 
 Cretaceous there was an extermination of the species then 
 on the globe, which was as complete as that closing the 
 Paleozoic era. No species have yet been proved to have 
 survived from the Cretaceous into the Cenozoic era, except 
 
REPTILIAN AGE. 203 
 
 possibly some kinds of Sharks. The species most likely to have 
 outlived the period of disturbance which intervened are the 
 species of the open ocean, as Sharks, since variations in the 
 climate of the globe and changes of level over its surface 
 affect but slightly the ocean's waters remote from coasts. 
 
 Besides the destruction of species, there was the final 
 extinction of several families and tribes. The great family 
 of Ammonites, and many others of Mollusks, all the genera 
 of Eeptiles excepting Crocodilus, and others in all depart- 
 ments of life, came to their end in the revolution. 
 
 From the occurrence of Cretaceous rocks in the structure 
 of mountains or about their tops, and the existence of 
 marine rocks of the next (or Tertiary) period only at low 
 levels upon the sides, or towards the foot, of the same moun- 
 tains, it has been discovered that the epoch of disturbance 
 or revolution was remarkable for the number of great moun- 
 tain-ranges which either began at that time their existence 
 above the oceans, or else had their altitude greatly increased. 
 The region occupied by a Cretaceous sea must have been 
 raised into a mountain-elevation before seashore Tertiary 
 strata could have been formed about its base. The Rocky 
 Mountains and Andes, Himalayas and Alps, received a large 
 part of their elevation subsequent to the Mesozoic era, and 
 some considerable part immediately at the close of the Cre- 
 taceous period, although the elevation in the case of each 
 of these great chains of the world was continued in progress 
 through the Tertiary and afterwards. 
 
 The Himalayas have no known Cretaceous rocks in their 
 structure ; but Oolitic beds occur at a height of 14,000 to 
 18,000 feet, and extend along at these elevations for 400 
 miles. (Strachey.) The land may in part have made its 
 emergence from the sea before the Cretaceous period began ; 
 whether so or not, it continued long after rising : the eleva- 
 tion of the western part of the chain about Cashmeer was 
 not completed until after the Tertiary period had well 
 
 18* 
 
204 MESOZOIC TIME. 
 
 advanced. The Apennines began their elevation about the 
 middle of the Cretaceous period, but made the most of their 
 altitude in the early Tertiary. The Andes have Cretaceo- 
 oolitic beds about their higher slopes, proving also their 
 elevation to have been essentially cotemporaneous with that 
 of the Eocky Mountains and other highest mountains of 
 the globe. 
 
 The facts will be better appreciated after a study of the 
 Tertiary formations, which afford part of the evidence on 
 which these conclusions are based. 
 
 Extermination of life. The proofs of elevation are so 
 many and so extensive that it is reasonable to infer that a 
 great change of climate must also have taken place over 
 the globe. The Arctic regions may have been elevated 
 more than lower latitudes, for Tertiary rocks do not occur 
 on the eastern borders of the American continent north of 
 the parallel of 42 N. to show that the continent was then 
 below its present level. The change of climate consequent 
 on the increase of Arctic lands, and the increased number and 
 height of mountain-chains, may, therefore, have been so 
 great as to have proved a principal cause of the extinction 
 of life that then took place both over the land and along 
 the oceanic borders. Should the cold winds and cold oceanic 
 currents of the northern part of the existing temperate 
 zone penetrate for a single year into the tropical regions, 
 they would produce a general extermination of the plants 
 and animals of the land, and also of those of the coast and 
 sea-borders, even to a great depth, as far as the cold oceanic 
 currents extended. If a change of climate took place at 
 the close of the Cretaceous, such as has been supposed, these 
 very results would then have happened; moreover, the 
 frigid air and waters would have found tropical life much 
 nearer to the pole than now, even over Europe and a largo 
 part of the United States. 
 
CENOZOIC TIME. 205 
 
 IY. CENOZOIC TIME. 
 
 1. Age of Mammals, Cenozoic time covers but one age, 
 the age of Mammals. 
 
 2. General characteristics, In the transition to this age 
 the life of the world takes on a new aspect. Trees of 
 modern types Oak, Maple, Beech, etc., and Palms unite 
 with Conifers to make the forests; Mammals of great 
 variety and size Herbivores, Carnivores, and others, suc- 
 cessors to the small semi-oviparous Mammals and Insect- 
 ivores tenant the land in place of Beptiles; true Birds 
 and Bats possess the air in place of reptilian Birds and 
 Pterodactyls ; Whales and Teliost or common Fishes, with 
 Sharks, mainly of modern type, occupy the waters in place 
 of Enaliosaurs, and almost to the exclusion of the ancient 
 tribes of Cestraciont Sharks and Ganoids. 
 
 It has already been shown that several of these modern- 
 izing features began to appear in the Mesozoic era. Thus, 
 in all geological as well as other history (as remarked on 
 page 154), every age has preparations for it in progress in 
 the age preceding. There are no abrupt transitions. 
 The Mammals, Birds, Teliosts, and Angiosperms of the 
 Eeptile world were precursors of a future and brighter era, 
 when these species should be the predominant races. The 
 type of Mammals appears in Cenozoic time under several 
 successive faunas of different species, each successively 
 exterminated, and finally expands till in number of kinds 
 and in the magnitude of its wild beasts the Mammalian age 
 far exceeds the Age of Man. These, also, disappear before 
 the last age opens and during its early progress. 
 
 MAMMALIAN AGE. 
 
 The age of Mammals is divided into two Periods: 1. 
 The Tertiary; 2. The Post-tertiary. 
 
206 CENOZOIC TIME MAMMALIAN AGE. 
 
 In the Tertiary the Mammals are all extinct species, and 
 the other species of life mostly so ; the number of living 
 species of Invertebrates (Kadiates, Mollusks, and Articu- 
 lates) varies from none in the early part of the period to 90 
 per cent, in the latter part. 
 
 In the Post-tertiary the Mammals are nearly all of extinct 
 species, but the Invertebrates are almost wholly of living 
 species, not over 5 per cent, being extinct. 
 
 I. TERTIARY PERIOD. 
 
 1. Epochs. 
 
 The beds of the Tertiary period have been divided by 
 Lyell into three series : 
 
 1. EOCENE (from the Greek eos, dawn, and kainos, recent). 
 Species all extinct. 
 
 2. MIOCENE (from meion, less, and kainos*) : 15 to 40 per 
 cent, of the species extinct. 
 
 3. PLIOCENE (from pleion, more, and kainos) : 50 to 90 per 
 cent, of the species extinct. 
 
 These subdivisions do not correspond to the epochs of the 
 period, either in Europe or America, although affording 
 convenient terms for Lower, Upper, and Middle Tertiary. 
 
 In North America the epochs are the following : 
 
 1. CLAIBORNE, or that of the Tertiary beds of Claiborne, 
 Alabama, the early Eocene. 
 
 2. JACKSON, or that of the beds of Jackson, Mississippi, 
 the Middle Eocene. 
 
 3. VICKSBURG, or that of the beds of Vicksburg, Missis- 
 sippi, the later Eocene. 
 
 4. YORKTOWN, or that of the beds of Yorktown, Yirginia, 
 in which 15 to 30 per cent, of the species are living, usually 
 called Miocene, but probably including part, at least, of the 
 Pliocene. 
 
 A fifth has been separated as Pliocene, or the SUMTER 
 epoch, based on observations on the beds in Sumter and 
 
TERTIARY PERIOD. 207 
 
 Darlington districts, South Carolina; but it is probably not 
 distinct from the Yorktown. (Conrad.) 
 
 2. Rocks: kinds and distribution. 
 
 The marine Tertiary beds of North America border the 
 continent south of New England along both the Atlantic 
 Ocean and the Mexican Gulf, like the Cretaceous. They 
 overlie nearly all the Cretaceous beds on the Atlantic 
 border, but extend less far inland on the Gulf border. (See 
 map on p. 69, in which the area is lined obliquely from the 
 left above to the right below). They spread northward 
 along the Mississippi to the mouth of the Ohio, and also 
 westward beyond this river into Texas, along the west side 
 of the Mexican Gulf; but the marine Tertiary beds do not, 
 like the Cretaceous, stretch north over the Rocky Mountain 
 region. There are, however, about the Upper Missouri and 
 over other parts of the slopes of these mountains, extensive 
 deposits of fresh-water Tertiary, the lowest layers of which 
 are of brackish-water origin. (On the map the area of this 
 fresh-water Tertiary is distinguished by being more openly 
 lined than those of the marine Tertiary.) The most northern 
 locality of Tertiary on the Atlantic coast is on Martha's 
 Vineyard. The Tertiary formation also occurs extensively 
 in California and Oregon, and in some places has a height 
 of 2000 fe'et above the sea. 
 
 The Eocene beds are best displayed in the Tertiary of the 
 Gulf border from the Mississippi Eiver to South Carolina, 
 and the marine Miocene beds on the Atlantic border from 
 New Jersey to South Carolina, though both occur in other 
 parts of the Tertiary region. The fresh-water Tertiary of 
 the Upper Missouri is at its base probably Eocene ; it con- 
 tains much lignite and many fossil leaves, like the lower 
 Eocene elsewhere. The rest is Miocene and Pliocene. 
 
 The Tertiary beds are generally but little consolidated: 
 they consist of compacted sand, pebbles, clay, earth that 
 
208 CENOZOIC TIME MAMMALIAN AGE. 
 
 was once the mud of the sea-bottom or of estuaries, mixed 
 often with shells, being just such kinds of deposits as are now 
 forming along the seashores and in the shallow bays and 
 estuaries of the coast, or in the shallow waters off the coast. 
 There are also some limestones made of shells ; and others 
 made of corals, resembling the reef-rock of coral seas. The 
 latter are found mainly in the States bordering on the 
 Mexican Gulf. Another variety of rock is the buhrstone, a 
 very cellular siliceous rock, flinty in texture, used, on account 
 of its being so hard and at the same time full of irregu- 
 lar cavities, for making mill-stones. It is found in South 
 Carolina. 
 
 The Tertiary of Great Britain occurs mostly in the south- 
 eastern part of England, in the London basin as it is called, 
 and on the southern and eastern borders of the island, 
 adjoining the Cretaceous. 
 
 On the continent of Europe the Paris basin is noted for 
 its Eocene strata and fossil Mammals. Other Tertiary 
 areas are those of the Pyrenean and Mediterranean regions, 
 those of Switzerland, of Austria, etc. Some of the marine 
 Eocene beds contain a fossil having the shape of a coin, 
 called a Nummulite (from the Latin nummus, a coin). One 
 is figured on page 59. Occasionally the beds are so far 
 made up of these Nummulites that they are called Nummu- 
 litic limestone. 
 
 These marine Eocene strata spread very widely over both 
 Europe, northern Africa, and Asia, occurring in the Pyre- 
 nees, forming some of their summits; in the Alps to a height 
 of 10,000 feet ; in the Carpathians, in Algeria, in Egypt, where 
 the most noted pyramids are made of Nummulitic limestone, 
 in Persia, in the western Himalayas (the region of Cash- 
 mere), to a height of 15,000 feet. The later Tertiary forma- 
 tions are much more limited in distribution, and many are 
 of terrestrial or fresh-water origin. 
 
 The rocks are similar to those of North America, but 
 
TERTIARY PERIOD. 209 
 
 with more of compact sandstone and compact limestone. 
 The sandstone is a very common building-stone in different 
 parts of Europe, being soft enough to be worked with faci- 
 lity, yet generally hardening on exposure, owing to the fact 
 that it contains calcareous particles (triturated shells), 
 which render the percolating waters or rain calcareous, so 
 that on evaporating they produce a calcareous deposit, as a 
 cement, among the grains of sand. 
 
 The Eocene formation of southeastern England consists of 
 bed of clay and sand, the lowest of sand sometimes con- 
 taining rolled flints. The Lower Eocene includes the Thanet 
 sands, Woolwich beds, London clay, and Bognor beds; the 
 Middle Eocene, the Bagshot beds, Headon group, arid others; 
 the Upper Eocene, the Hempstead beds near Yarmouth. The 
 Older Pliocene includes the Coralline crag and Red crag of 
 Suffolk; and the Newer Pliocene, the Norwich crag, which 
 is of fluvio-marine origin. No marine Miocene beds have 
 yet been identified in Great Britain. 
 
 3. Life. 
 1. Plants. 
 
 The great feature of the vegetation is the prevalence of 
 the class of Angiosperms, which made its first appearance 
 in the Cretaceous. Leaves of Oak, Poplar, Maple, Hickory, 
 Dogwood, Mulberry, Magnolia, Cinnamon, Fig, Sycamore, and 
 many others, have already been found in both American 
 and European Tertiary strata, besides the remains of Palms 
 and Conifers. A leaf of a Tertiary Fan-palm (species of 
 Sdbal) found in the Upper Missouri must have been, when 
 entire, 12 feet in breadth. Nuts are also common in some 
 beds, as at Brandon, Yermont. Fig. 332 is the leaf of an 
 Oak ; fig. 333, of a species of Cinnamon ; fig. 334, of a Palm ; 
 fig. 335, the nut of a beech, closely like that of the common 
 beech; fig. 336, another nut, from Brandon, of unknown 
 relations. 
 
210 
 
 CENOZOIC TIME MAMMALIAN AGE. 
 
 The Eocene Plants in central and southern Europe have, 
 in general, a striking resemblance to those of Australia, and 
 the Miocene and Pliocene to those of America. The forests 
 of England, in the Eocene, abounded in Palms. 
 
 The microscopic plants which form siliceous shells called 
 Diatoms (p. 61) make extensive deposits in some places. 
 
 Fig. 332, Quercus myrtifolia ? ; 333, Cinnamomum Mississippiense ; 334, Calamopsis Dame; 
 335, Fagus ferruginea ? ; 336, Carpolithes irregularis. 
 
 One stratum near Eichmond, Virginia, is 30 feet thick, and 
 is many miles in extent; and another, near Bilin in Bohe- 
 mia, is 14 feet thick. The material from the latter place 
 was used as a polishing-powder (and called Tripoli, or 
 polishing-slate) long before it was known that its fine grit 
 was owing to the remains of microscopic life. Ehrenberg 
 
TERTIARY PERIOD. 
 
 211 
 
 has calculated that a cubic inch of the fine earthy slate con- 
 tains about forty-one thousand millions of organisms. 
 
 2. Animals. 
 
 The most prominent fact with regard to the Tertiary 
 Invertebrates is their general resemblance to modern 
 species. Although a number of the genera are extinct, and 
 all the Eocene species, there is still a modern look in the 
 remains, and the specimens have often the freshness" of a 
 shell from a modern beach. 
 
 The species of Tertiary shells found in the European beds 
 number about 6000; while not over 3000 have been gathered 
 from the North American beds. 
 
 The following are figures of a few species of the Clai- 
 borne epoch. Fig. 337 represents an Eocene Oyster; fig. 338, 
 
 Figs. 337-341. 
 
 MOLLUSKS :' Fig. 337, Ostrea sellaeformig ; 338, Crassatella alta ; 339, Astarte Conradi ; 340, 
 Cardita planicosta; 341, Turritella carinata. 
 
 a species of Crassatella; fig. 339, an Astarte; fig. 340, a Car- 
 dita; and fig. 341, a Turritella: all are from Claiborne, 
 Alabama. 
 
 19 
 
212 
 
 CENOZOIC TIME MAMMALIAN AGE. 
 
 Figures 342 to 345 are of species of shells of the York- 
 town epoch, from Virginia; figs. 342, 343 represent a very 
 
 42 
 
 Figs. 342-345. 
 44 
 
 GASTEBOPOD: Figs. 342, 343, Crepidula costata. CONCHIFERS : Fig. 344, Yoldia limatula; 
 345, Oallista Sayana. 
 
 common Crepidula, upper and under sides. The species of 
 the epoch include the common Oyster and Clam, and other 
 modern species ; and these are, therefore, among the most 
 ancient of living species on the globe; for, until the Miocene 
 epoch opened, every species of Mollusk that had existed on 
 the globe had become extinct, and every species of other 
 kinds of life, if we except some Protozoans and Protophytes. 
 
 With regard to Vertebrates the points of special interest 
 are the following : 
 
 1. In the class of Fishes : (1) The prevalence of Teliosts, 
 or fishes allied to the Perch and Salmon, as already stated; 
 and (2) the abundance of Sharks, some of them having 
 teeth 6 inches long and broad. The teeth of sharks are the 
 durable part of the skeleton; they are very abundant in 
 both Eocene and Miocene beds. Fig. 59, p. 52, represents 
 a tooth of the Carcharodon angustidens. The larger teeth 
 above alluded to belong to the Carcharodon megalodon, and 
 are found at different places on the Atlantic border from 
 Martha's Vineyard south. Fig. 58 represents the tooth of 
 
TERTIARY PERIOD. 213 
 
 another common kind of Shark, a species of Lamna (JJ. 
 elegans), from Claiborne. 
 
 In the class of .Reptiles: The existence of numerous 
 Crocodiles and Turtles. The shell of one of the Miocene Tur- 
 tles, found fossil in India, had a length of 12 feet, and the 
 animal is supposed to have been 20 feet long. The first of 
 Snakes, moreover, occur in the Eocene. 
 
 In the class of Birds : The species found are not reptilian 
 or long-tailed, but like modern birds; they are related to 
 the Pelican, Waders, Pheasants, Perchers, Vultures. But fossil 
 birds are of very rare occurrence; none have yet been found 
 in America, although Mammalian remains are common. 
 
 In the class of Mammals : The occurrence of the first of 
 Whales, the first of Carnivores, Herbivores, Rodents, Monkeys, 
 and of other tribes, indicating a large population of brute 
 animals wholly different from the present in species, though, 
 in general, related to the modern kinds in form and struc- 
 ture. A few, however, are widely diverse from any thing 
 in existence, such combinations as the mind would never 
 have imagined without aid from the skeletons furnished by 
 the strata. 
 
 In the early Eocene there appear to have been more 
 Herbivores than Carnivores; but afterward the Carni- 
 vores were as common as now. 
 
 Cuvier first made known to science the existence of fossil 
 Mammals. The remains from the earthy beds about Paris 
 had been long known, and were thought to be those of 
 modern beasts. But, through careful study and comparisons 
 with living animals, he was enabled to bring the scattered 
 bones together into skeletons, ascertain the tribe to which 
 they belonged, and determine the food and mode of life of 
 the ancient but now extinct species. Cuvier acquired his 
 skill by observing the mutual dependence which subsists 
 between all parts of a skeleton, and, in fact, all parts of 
 an animal. A sharp claw is evidence that the animal has 
 
214 
 
 CENOZOIC TIME MAMMALIAN AGE. 
 
 trenchant or cutting molar teeth, and is a flesh-eater; a 
 hoof, that he has broad molars and is a grazing species; 
 and, further, every bone has some modification showing the 
 group of species to which it belongs, and may thus be an 
 indication, in the hands of one well versed in the subject, 
 of the special type of the animal, and of its structure, even 
 to its stomach within and its hide without. 
 
 One of these Paris beasts is called a Paleothere (from the 
 Greek palaios, ancient, and therion, wild beast. Its form, as 
 restored, is shown in figure 346. It is related to the modern 
 Tapir, and was of the size of a horse. Another kind, called 
 
 Fig. 346. 
 
 Palseotherium magnum. 
 
 an Anoplothere, was of more slender habit, and somewhat 
 resembled a stag. There were others, related to the hog, or 
 Mexican Peccary, and to the horse ; also some Carnivores, a 
 Bat, and an Opossum. 
 
 The only American Eocene Mammals that have been dis- 
 covered are those of the ocean, as Whales. The bones 
 of a species of whale, called a Zeuglodon, occur in many 
 places in the Gulf States; and in Alabama the vertebrae 
 were formerly so abundant as to have been built up into 
 
TERTIARY PERIOD. 
 
 215 
 
 stone walls, or burnt to rid the fields of them. The living 
 animal was probably 70 feet in length. One of the larger 
 vertebrae measures a foot and a half in length and a foot in 
 diameter. 
 
 The Miocene beds of the "Bad Lands" on the White 
 Eiver, in the Upper Missouri region, have afforded remains 
 of a large number of Miocene quadrupeds. Among them, 
 according to Leidy, there are eight Carnivores related 
 somewhat to the Hyena, Dog, and Panther ; 25 Herbivores, 
 including 2 Ehinoceroses, and species approaching the Tapir, 
 Peccary, Deer, Camel, Horse ; and 4 Rodents, besides many 
 
 Fig. 347. 
 
 Tooth of Titanotherium Proutii (X M)- 
 
 Turtles. Figure 347 represents a tooth, half the natural 
 size, of a Titanothere, an animal related to the Tapir and 
 Paleothere, but of elephantine size, standing probably 7 or 
 
 Fig. 348. 
 
 Teeth of Rhinoceros Nebrascensis. 
 
 8 feet high. Figure 348 represents a few of the teeth of 
 one of the Rhinoceroses. 
 
 19* 
 
216 
 
 CENOZOIC TIME MAMMALIAN AGE. 
 
 Fig. 349. 
 
 Among Mammals of the European Miocene there were 
 Elephants, Mastodons, Deer, and other Herbivores, many 
 Carnivores, Monkeys, Ant-eaters, etc. One of the most sin- 
 gular species is the Dinothere, the form of the skull of which 
 the only part of the skeleton found is shown in the 
 annexed figure; its actual 
 length is 3 feet 8 inches. It 
 appears to have had a pro- 
 boscis like an Elephant, but 
 the tusks proceeded from the 
 lower instead of upper jaw, and 
 were bent downward. Some sup- 
 pose it to have been related to 
 the Elephant, and others to the 
 marine Manatus and Dugong. 
 
 In fresh-water Pliocene beds 
 of the Upper Missouri there are 
 remains of a fauna totally dif- 
 ferent in species from that of 
 
 the Miocene. It included a Rhinoceros, an Elephant of great 
 size, a Mastodon, 3 species of Camel, 4 of the Horse family, 
 Deers, a Wolf, a Fox, a Beaver, and a Porcupine, all of 
 extinct species; it had, in its Camels and Ehinoceros and 
 Elephant, quite an Oriental character, as Leidy observes, 
 though still prominently North American in the preponder- 
 ance of Ungulates, and the absence of the South American 
 type of Edentates or Sloths. 
 
 The earliest of the Bovine or Ox group occur in the 
 European Pliocene. 
 
 4. General Observations. 
 
 1. Geography. The Tertiary period completed mainly the 
 work of rock-making, along the borders of the continent, 
 which had been in progress during the Cretaceous period. 
 The accompanying map shows approximately the part of 
 
 Dinotherium giganteum 
 
TERTIARY PERIOD. 217 
 
 the continent of North America under the sea when the 
 Tertiary era began. By comparing'it with the map of the 
 
 Fig. 350. 
 
 Map of North America in the early part of the Tertiary Period. 
 
 Cretaceous continent, p. 196, it is seen that the Eocky 
 Mountain region had become dry land in the interval; but, 
 as Hayden has shown by the discovery of brackish-water 
 beds in the lowest Tertiary of the Upper Missouri region, 
 the elevation was at first small; and its present height was 
 gradually attained later in the Tertiary period. The great 
 river-system of the Mississippi, embracing slopes from the 
 Eocky Mountains on -the west to the Appalachians on the 
 east, then for the first time became complete. The Mexican 
 Gulf was much larger than at present; but there was not 
 
218 CENOZOIC TIME MAMMALIAN AGE. 
 
 that long extension far northward which it had during the 
 Cretaceous period. Florida was still submerged, and also 
 all the bays of'the Atlantic coast south of New York. After 
 the Eocene epoch the Mexican Gulf became much more 
 contracted by an elevation of the coast along the Gulf; and 
 by the close of the Tertiary period the continent appears to 
 have reached nearly its present outline. 
 
 In the Orient the Eocene era was one of very extensive 
 submergence of the land, as shown by the distribution of 
 the marine beds over Europe, Asia, and northern Africa, 
 as stated on page 208. After the Eocene, the greater part 
 of these continental seas had become dry land, and in gene- 
 ral continued so afterward ; for the Miocene and Pliocene are, 
 comparatively, very limited in extent. The fact that many 
 of the great mountains of the globe, as the Pyrenees, Alps, 
 Carpathians, Himalayas, etc., were only partly made, is here 
 proved by their containing Eocene rocks in their structure, 
 or by their bearing them about their summits. 
 
 By evidence of this kind, the presence of Eocene strata, 
 it is learned that the elevation of the Pyrenees, though 
 commenced before the close of the Cretaceous, was mainly 
 produced in the middle or later part of the Eocene, as also 
 that of the Julian Alps, the Apennines and Carpathians, 
 and that of heights in Corsica. The elevation of the western 
 Alps, including Mont Blanc, is referred by Elie de Beau- 
 mont to the close or latter part of the Miocene epoch; and 
 that of the eastern Alps, along the Bernese Oberland, to 
 the close of the Pliocene. An elevation of 3000 feet took 
 place in Sicily after the Pliocene. The Himalayas, in their 
 western part about Cashmere, have nummulitic or Eocene 
 beds, at a height of 15,000 feet; so that even this great chain, 
 although earlier elevated to the east, was not completed 
 before the Middle Eocene; and even later than this, as later 
 Tertiary beds at lower levels show, it received a consider- 
 able part of its elevation. 
 
POST-TERTIARY PERIOD. 219 
 
 Many parts of the region of the Andes were raised 8000 
 to 5000 feet or more in the course of the Tertiary period. 
 
 Climate. In Europe, the fact that the plants of the Eocene 
 were Australian in character over its central and southern 
 portions, and that Palms abounded in Britain, is evidence 
 of a tropical or sub-tropical climate on the south, and sub- 
 tropical or warm-temperate on the north. 
 
 Again, the plants of the Miocene, in southern Europe, are 
 supposed to indicate a sub-tropical climate there during the 
 middle Tertiary. 
 
 In North America, the Eocene palms and other plants of 
 the Upper Missouri region show that the temperature now 
 found in the Dismal Swamp in North Carolina characterized 
 in the early Tertiary era the region of the Upper Missouri, 
 the vicinity of the Great Lakes, and Yermont (where is the 
 Brandon deposit of nuts and lignite). 
 
 The Camels, Rhinoceroses, and other animals of the Pliocene 
 of the Upper Missouri seem to prove that a warm-tem- 
 perate climate still prevailed there in that closing epoch of 
 the Tertiary period. It is therefore plain that the Earth 
 had not its present diversity of zones of climate ; and Europe 
 was apparently little if any colder in the Eocene than in 
 the Jurassic era. If the interval between the Cretaceous 
 and Tertiary was one of unusual cold, through Arctic and 
 other elevations, as suggested on page 204, the cold epoch 
 had mostly passed when the Eocene era opened. 
 
 II. POST-TERTIARY PERIOD. 
 
 1. General characteristics. The Post-tertiary period was 
 remarkable (1) as the period of culmination of the type of 
 Mammals; and (2) as that of high-latitude movements and 
 operations both north and south of the equator. 
 
 2. Epochs. The epochs, as observed in North America, are 
 two : 
 
 1. The GLACIAL, or the epoch when, over the higher lati- 
 
220 CENOZOIC TIME MAMMALIAN AGE* 
 
 tudes, the continents underwent great modifications in the 
 features of the surface through the agency of ice. 
 
 2. The CHAMPLAIN, an epoch when the ice had disap- 
 peared, and the same high-latitude portions of the continent, 
 and to a less extent the lower, became covered by extensive 
 fluvial and lacustrine formations, and also, in some places, 
 by marine. 
 
 These epochs were followed in America by another, the 
 TERRACE epoch, which forms a transition to the Age of 
 Man; when these fluvial, lacustrine, and marine formations 
 were made into terraced heights by an elevation of the con- 
 tinent which was also in the main a high-latitude movement. 
 
 1. GLACIAL EPOCH. 
 
 The special effects of the operations going on in the 
 Glacial epoch are the following : 
 
 1. Transportation. The transportation of a vast amount 
 of earth and stones from the higher latitudes to the lower, 
 over a large part of the breadth of a continent. 
 
 The material consists of earth and pebbles, or stones, 
 confusedly mingled or unstratified, and is called drift. It 
 contains no marine fossils or relics. 
 
 New England, Long Island, Canada, New York, and the 
 States west to Iowa and beyond, are in many parts thickly 
 covered with drift; it reaches south to the latitude of 39, 
 or nearly to the southern limits of Pennsylvania, Ohio, 
 Indiana, Illinois, and central Missouri, being hardly trace- 
 able south of the Ohio Eiver. 
 
 The stones are of all dimensions, from that of a small pebble 
 to masses as large as a moderate-sized house. One at Brad- 
 ford in Massachusetts is 30 feet each way, and its weight is 
 estimated to be at least 4,500,000 pounds. Many on Cape 
 Cod are 20 feet in diameter. One lying on a naked ledge at 
 "VYhitingham in Yermont measures 43 feet in length and 30 
 in height and width, or 40,000 cubic feet in bulk, and was 
 
POST-TERTIARY PERIOD. 
 
 221 
 
 probably transported across Deerfield valley, the bottom of 
 which is 500 feet below the spot where it lies. 
 
 The drift-material is coarsest to the north. 
 
 The directions in which it travelled are in general between 
 southwestward and southeastward, and mostly between 
 southward and southeastward. The material was carried 
 southward across the great lakes and across Long Island 
 Sound, the land to the south, in each case, being covered 
 with stones from the land to the north. 
 
 The distance to which the stones were transported, as 
 learned by comparing them with the rocks in place to the 
 north, is mostly between 20 and 40 miles, though in some 
 cases 60 miles or more. 
 
 2. Scratches. The rocky ledges over which the drift was 
 borne are often scratched, in closely crowded parallel lines, 
 as in the annexed figure (fig. 351). The scratchings or groov- 
 
 Fig. 351. 
 
 Drift groovings or scratches. 
 
 ings are often deep and broad channellings, at times even a 
 foot in depth and several feet wide, as if made by a tool of 
 great size as well as power. At Howe in Massachusetts and 
 on the top of Mount Monadnock, the scratches are of this 
 
222 CENOZOIC TIME MAMMALIAN AGE. 
 
 remarkable character. These scratches occur wherever the 
 drift occurs, provided the underlying rocks are sufficiently 
 durable to have preserved them, and they are usually of 
 great uniformity in any given region. Frequently two or 
 more directions may be observed on the same surface, as if 
 made at different epochs. 
 
 They are found in the valleys and on the slopes of moun- 
 tains to a height, on the Green Mountains, of 5000 feet. 
 
 They often cross slopes and valleys obliquely, that is, 
 without following the direction of the slope or valley. But, 
 when so, it is usually found that these valleys are tributary 
 to some great valley to which the oblique scratches are more 
 or less nearly parallel. For the courses of the scratches 
 generally conform to the directions of the great valleys of 
 the land, rather than to those of the smaller. Thus, in the 
 Hudson River valley, between the Catskills and Green Moun- 
 tains, the scratches have mostly the Hudson River course ; 
 and in the Connecticut River valley, between the Green 
 Mountains and the heights of eastern Massachusetts, they 
 conform in general to the course of the Connecticut valley. 
 
 While the courses are generally from the northward to 
 the southward, like those of the drift, there are cases of 
 eastward and westward scratches. Such occur on the eleva- 
 tions south of the Mohawk valley, near Cherry Valley, and 
 over the bottom of the Mohawk valley, near Amsterdam, 
 at various localities ; they are here parallel to the course of 
 the great Mohawk valley. 
 
 The stones, or boulders, are often scratched like the rocks. 
 
 European drift. The drift in Europe presents the same 
 general course and peculiarities as in North America. It 
 reaches south to about latitude 50. The region south of 
 the Baltic, and parts of Great Britain, are covered with 
 drift and stones from Scandinavia. The distance of travel 
 varies from 5 or 10 miles to 500 or 600. 
 
 3. Fiords. Fiords are deep narrow sea-channels, running 
 
POST-TERTIARY PERIOD. 223 
 
 many miles into the land. They occur on the coasts of Nor- 
 way, Britain, Maine, Nova Scotia, Labrador, Greenland, on 
 the coast of western North America north of the Straits of 
 de Fuca, and that of western South America south of lati- 
 tude 41 S. 
 
 Fiords are thus, like the drift, confined to the higher lati- 
 tudes of the globe ; and the two may have been of cotempo- 
 raneous origin. 
 
 Origin of the drift. Nothing but moving ice could have 
 transported the drift with its immense boulders. Ice is per- 
 forming this very work now in the glacier regions of the 
 Alps and other icy mountains, and stones of as great size 
 have in former times been borne by a slow-moving glacier 
 from the vicinity of Mont Blanc across the lowlands of 
 Switzerland to the slopes of the Jura Mountains, and left 
 there at a height of 2203 feet above the present level of Lake 
 Geneva. Moreover, there are scratches, of precisely the 
 same character as to numbers, depth, and parallelism, in the 
 granitic and limestone rocks of the ridges; and, besides, 
 the transported material is left unstratified, when not after- 
 wards acted upon and redistributed by Alpine torrents. 
 
 Icebergs also transport earth and stones, as in the Arctic 
 seas; and great numbers are annually floated south to the 
 Newfoundland banks, through the action of the northern 
 or Labrador current, where they melt and drop their great 
 boulders and burden of gravel and earth to make unstrati- 
 fied deposits. It is objected to icebergs as the cause of the 
 phenomena of drift, that they could not have covered great 
 surfaces so regularly with scratches, and, again, that there 
 are no marine relics in the unstratified drift to prove that 
 the continent was under the sea in the Glacial epoch. 
 
 There is a seeming difficulty in the Glacier theory, from 
 the supposed want of a sufficient slope in the surface to 
 produce movement. A slope, however, of one degree would 
 be enough. The production of the degree of cold required 
 
 20 
 
224 CE.NOZ01U TIME MAMMALIAN AGE. 
 
 to make a glacial epoch is an indication that the continent 
 was considerably higher than it is now over its higher lati- 
 tudes ; and the fiords are other evidence to the same effect, 
 since they must have been scooped out when the land was 
 above the sea-level, so that running water or ice could have 
 carried on the erosion by which they were made. If a great 
 glacier, covering the land, had moved along through its 
 extent but a single mile, it would have made scratches every 
 where beneath it; and 50 miles are all that would have been 
 required in order to have transported the boulders the dis- 
 tances they are known to have travelled in North America. 
 The Connecticut valley appears to have been the course 
 of one great independent glacier; the Hudson valley, of 
 another; and the Mohawk valley, in the latter part of the 
 epoch at least, of another. 
 
 2. CHAMPLAIN EPOCH. 
 
 The principal deposits of the Champlain epoch are of 
 three kinds : 
 
 (1.) Alluvial, or those formed along river-valleys by the 
 action of the streams. 
 
 (2.) Lacustrine, or those formed about lakes. 
 
 (3.) Sea-border or marine, or those formed on or near sea- 
 coasts, and often containing marine remains. 
 
 The alluvial deposits occur in all or nearly all the river- 
 valleys within the drift latitudes of the North American 
 continent, from Maine to Oregon and California; and they 
 exist even farther south, in Kentucky and Tennessee, and 
 perhaps in the Gulf States. 
 
 The beds consist of earth, clay, sand, or pebbles, or of 
 mixtures of these materials. They overlie the unstratified 
 drift wherever the two are in contact. 
 
 They form at present elevated alluvial flats on one or 
 both sides of a river-valley. Their elevation above the bot- 
 tom of the valley is greater in northern New England than 
 
POST-TERTIARY PERIOD. 
 
 225 
 
 in southern ; and there is a like difference between those of 
 the northern and southern parts of the States to the west 
 of New England. 
 
 The flats have great extent along the Connecticut River 
 and its various tributaries. The view in fig. 352 represents 
 
 Fig. 352. 
 
 Terraces on the Connecticut River, south of Hanover, IS. II. 
 
 a scene a few miles below Hanover in New Hampshire. 
 There are here three different levels, or terraces, in the 
 
 Fig. 353. 
 
 Section of a valley in the Champlain epoch, with dotted lines showing the terraces of the 
 
 Terrace epoch. 
 
 alluvial formation ; the upper shows the total thickness of 
 the formation down to the river-level. 
 
226 CENOZOIC TIME MAMMALIAN AGE. 
 
 Figure 353 represents a section of a valley, with the allu- 
 vial formation,//, filling it, and the ehannel of the river at 
 R. Were the country to be elevated, the river would dig 
 out a deeper channel as the elevation went on, and thus the 
 alluvial formation would finally be left far above the river, 
 beyond the reach of its waters. The river would at the 
 same time wear away a portion of the alluvium either side 
 during its floods, and thus make room for a lower flat on its 
 banks, over which the flooded waters would spread; for 
 every river, not confined by rocks, has both its channel and 
 its flood-ground. 
 
 The lacustrine deposits are of similar character, of like 
 distribution over the continent, and in equally elevated 
 positions above the present level of the water they border. 
 The great lakes, as well as the smaller lakes of the country, 
 are bordered by them. 
 
 The sea-border deposits are found along the borders of the 
 sea, and often have the character of elevated beaches. They 
 are found at many places on the coasts of New England, 
 both southern and eastern. At several localities, in Maine 
 they afford shells at heights not exceeding 200 feet above the 
 sea-level. They form deposits of great thickness along the 
 St. Lawrence, as near Quebec, Montreal, and Kingston; at 
 Montreal they contain numerous marine shells at a height 
 of 400 to 500 feet above the river. They border Lake 
 Champlain, beigig there 393 feet in height above its level; 
 and, besides marine shells, the remains of a whale have been 
 taken from the beds. 
 
 In the Arctic, similar deposits full of shells are common, 
 at different elevations up to 600 or 800 feet, and in some 
 places 1000 feet, above the sea-level. 
 
 These sea-border deposits, now elevated, must have been 
 at the water-level, or below it, in the Champlain epoch. The 
 facts prove that the river St. Lawrence was at that time 
 an arm of the sea, of great breadth, with the bordering land 
 
POST-TERTIARY PERIOD. 227 
 
 400 to 500 feet below its present level; that Lake Champlain 
 was a deep bay opening into the St. Lawrence channel, and that 
 it had its whales and seals as well as sea-shells ; that the coast 
 of Maine was 50 to 200 feet below its present level, and 
 southern New England 30 feet or more. 
 
 The present elevated positions of the alluvial and lacustrine 
 formations over the wide extent of the continent are equally 
 good evidence that its interior, in the Champlain epoch, was 
 below its present level. 
 
 There is thus proof that the whole northern portion of 
 the continent w T as less elevated than now. In fact, the 
 whole continent may have been lower ; but, if so, the northern 
 parts must have been most depressed, since the sea-border, 
 alluvial, and lacustrine formations are all at higher elevations 
 to the north, or near the northern boundary of the United 
 States, than they are to the south. 
 
 While, therefore, the facts connected with the Glacial 
 epoch favor the view that the northern portions of the con- 
 tinent were then much raised above their present level, those of 
 the next or Champlain epoch prove that it was afterwards 
 much below its present level. We hence learn that there was 
 an upward high-latitude movement for the Glacial epoch, 
 and a downward for the Champlain epoch, and that the 
 latter movement brought to its close the epoch of ice, by 
 occasioning a warm climate. 
 
 
 3. TERRACE EPOCH. 
 
 When the Champlain epoch was in progress, the upper 
 plain of the sea-border formations, now so elevated, was at 
 the sea-level ; and the high alluvial plains along the rivers 
 were the flood-grounds of the rivers. Since then the land has 
 been raised ; and during the progress of the elevation the 
 alluvial formations were cut into terraces, as represented in 
 fig. 352, p. 225, and the sea-border formations, also, were cut 
 into other terraces, or plains, of different levels. The epoch 
 
 20* 
 
228 CENOZOIC TIME MAMMALIAN AGE. 
 
 of this elevation is hence called the Terrace epoch. It con- 
 stitutes the transition to the Age of Man. 
 
 In figure 353 there are dotted lines showing the levels of 
 the river and its flood-plain at different periods in this ele- 
 vation ; and fig. 354 represents the terraces completed. The 
 successive terraces are not necessarily evidence of as many 
 
 Fig. 354. 
 
 Section of a valley with its terraces completed. 
 
 successive elevations of the continent, yet may be so in 
 some cases. 
 
 jis already stated, the alluvial formations throughout the 
 continent, along its various rivers and lakes, are raised high 
 above the present flood-plains of the rivers or lakes, and to 
 a greater height in the northern portions of the country 
 than in the southern. Hence, while the Champlain epoch 
 was one of a low level in the continent, especially at the 
 north, the Terrace epoch was one of a rising again until 
 the continent reached its present height; and this rising 
 was greatest at the north. 
 
 The high-latitude oscillations of this part of geological 
 history were hence an upward movement for the Glacial 
 epoch ; a downward for the Champlain epoch ; an upward 
 again for the Terrace epoch. There is no evidence that the 
 movement resulted anywhere in the raising of a mountain- 
 range; there was simply a gentle rising, then a sinking, and 
 then a rising again of the general surface. 
 
 4. CHAMPLAIN AND TERRACE EPOCHS IN EUROPE. 
 There are elevated alluvial, lacustrine, and sea-border 
 formations, of great extent, in Britain and over the higher 
 
POST-TERTIARY PERIOD. 229 
 
 latitudes of Europe, and also other evidence that these 
 epochs were there represented by phenomena similar to 
 those of America. But the limits of the epochs have not 
 been made out, and are probably less clearly denned. The 
 Glacial epoch may have been more prolonged, and the 
 grander northern oscillations complicated by local changes 
 of level. Europe has had its lofty glacial mountains ever 
 since the closing Tertiary period. It is not improbable that 
 the existing glaciers of Norway and the Alps are continuations 
 of portions of the more ancient glaciers of the continent. 
 After the Champlain epoch there was a time of unusual cold in 
 Europe; and a glacier then covered all Switzerland between 
 the Alps and the Juras (p. 223) ; for the transported stones 
 and earth of the glacier cover the alluvial and lacustrine 
 deposits. The simplicity observed in the order of events in 
 American geological history is not found in any part of 
 the European. 
 
 Among the British terraces those of Glen Roy in Scot- 
 land, called Parallel roads, or Benches, are especially noted. 
 There are three, one above the other; the highest 1139 feet 
 above tide-level, the second 1039 feet, the third 847 feet. 
 Others exist along many of the rivers and about the lakes, 
 as well as on the sea-borders. 
 
 LIFE OF THE POST-TERTIARY. 
 
 The invertebrate species of the Post-tertiary, and probably 
 the plants, were nearly or quite all identical with the exist- 
 ing species. The shells and other invertebrate remains 
 found in the beds on the St. Lawrence, Lake Champlain, 
 and the coast of Maine, are all similar to those now found 
 on the Labrador and Maine coasts. 
 
 The life of the period of greatest interest is the Mam- 
 malian, which type, as already remarked, then culminated. 
 This culmination appears in (1) the number of species, 
 (2) the multitude of individuals, (3) the magnitude of the 
 
230 CENOZOIC TIME MAMMALIAN AGE. 
 
 animals, the period in each of these particulars exceeding 
 the present age. 
 
 The remains in America have not been found in the 
 unstratified drift, but only in the overlying Champlain 
 deposits, or possibly those of more recent origin. In 
 Europe they are not excluded from the drift. 
 
 1. Europe and Asia. The bones of Mammals are found in 
 caves that were their old haunts; in drift and alluvium; in 
 sea-border deposits ; in marshes, where the animals appear 
 to have been mired ; in ice, preserved from decay by the 
 intense cold. 
 
 The caves in Europe were the resort especially of the 
 Great Cave Bear ( Ursus spelceus), and those of Britain of the 
 Cave Hyena (Hycena spelced}. Into their dens they dragged 
 the carcases or bones of other animals for food, so that relics 
 of a large number of species are now mingled together in 
 the earth, or stalagmite, which forms the floor of the cavern. 
 In a cave at Kirkdale, England, portions of at least 75 
 Hyenas have been made out, besides remains of an Elephant, 
 Tiger, Bear, Wolf, Fox, Hare, Weasel, Rhinoceros, Horse, 
 Hippopotamus, Ox, and Deer, all of which are extinct species. 
 A cave at Gaylenreuth is said to have afforded fragments 
 of at least 800 individuals of the Cave Bear. 
 
 The fact that the numbers of species and of individuals 
 in the Post-tertiary was greater than now, may be inferred 
 from comparing the fauna of Post-tertiary Great Britain 
 with that of any region of equal area in the present age. 
 The species included gigantic Elephants, two species of 
 Rhinoceros, a Hippopotamus, three species of Oxen, two of 
 them of colossal size, the Irish Elk (Megaceros Hibernicus^ 
 whose height to the summit of its antlers was 10 to 11 feet, 
 and the span of whose antlers was 8 feet, or twice that of 
 the American Moose, Deer, Horses, Boars, a Wild-cat, Lynx, 
 Leopard, a Tiger larger than that of Bengal, a large Lion 
 called a Machcerodus, having sabre-like canines sometimes 
 
POST-TERTIARY PERIOD. 231 
 
 8 inches long, the Cave Hyena, Cave Bear, besides various 
 smaller species. 
 
 The Elephant (JElephas primigenius) was nearly a third 
 taller than the largest modern species. It roamed over 
 Britain, middle and northern Europe, and northern Asia 
 even to its Arctic shores. Great quantities of tusks have 
 been exported from the borders of the Arctic sea for ivory. 
 These tusks sometimes have a length of 12? feet. Near the 
 beginning of the century, one of these Elephants was found 
 frozen in ice at the mouths of the Lena; and it was so well 
 preserved that Siberian dogs ate of the ancient flesh. Its 
 length to the extremity of the tail was 16 feet, and its 
 height 9 feet. It had a coat of long hair. But no amount 
 of hair would enable an Elephant now to live in those 
 barren, icy regions, where the mean temperature in winter 
 is 40 F. below zero. 
 
 Although there were many Herbivores among the Post- 
 tertiary species of the Orient, the most characteristic ani- 
 mals were the great Carnivores. The period was the time 
 of triumph of brute force and ferocity, and the Orient 
 and perhaps especially the part of it in which lay Britain 
 and Europe was the scene of its triumph. 
 
 2. North America. There were great Elephants and Mas- 
 todons, Oxen, Horses, Stags, Beavers, and some Edentates, in 
 Post-tertiary North America, unsurpassed in magnitude by 
 any in other parts of the world. Herbivores were the cha- 
 racteristic type. Of Carnivores there were comparatively 
 few species; no bone-caverns have been discovered. Figure 
 355 (from Owen) represents the specimen of the American 
 Mastodon now in the British Museum. The skeleton set up 
 by Dr. Warren in Boston has a height of 11 feet and a 
 length to the base of the tail of 17 feet. It was found in a 
 marsh near Newburgh, New York. The American Elephant 
 was fully as large as the Siberian. 
 
 3. South America. South America had its Carnivores, its 
 
232 CENOZOIC TIME MAMMALIAN AGE. 
 
 Mastodons, and other Herbivores ; but it was most remark- 
 able for its Edentates, or Sloths, which were wonderful both 
 
 Fig. 355. 
 
 Skeleton of Mastodon giganteus. 
 
 for their magnitude and numbers. Fig. 356 shows the form 
 and skeleton of one of these animals, the Megathere. It 
 exceeded in size the largest Rhinoceros : a skeleton in the 
 British Museum is 18 feet long. It was a clumsy, sloth-like 
 beast, but exceeded immensely the modern sloth in its size. 
 Another kind of Edentate had a shell like a turtle, and was 
 somewhat related to the Armadillo. One of them is called 
 a Glyptodon (fig. 357). The animals of this kind were also 
 gigantic, the Glyptodon here figured having had a length, 
 to the extremity of the tail, of nine feet. 
 
 South America was eminently the continent of Edentates. 
 
POST-TERTIARY PERIOD, 
 
 4. Australia. Post-tertiary Australia contained Marsupial 
 animals almost exclusively, like modern Australia; but 
 
 Fig. 356. 
 
 Megatherium Cuvieri (X fa)- 
 
 these partook of the gigantic size so characteristic of the 
 Mammalian life of the period. One species, called Dipro- 
 todon, was as large as a Hippopotamus. 
 
 Conclusions. The facts sustain the following conclusions: 
 
 Fig. 357. 
 
 Glyptodon clavipes (X a\))- 
 
 (1.) The Post-tertiary period was the culminant time of 
 Mammals, both as to their numbers and magnitude. 
 
234 CENOZOIC TIME. 
 
 (2.) Each continent was gigantic in that type of Mam- 
 malian life which is now eminently characteristic of it : The 
 Orient, in Carnivores, and, it may be added, Quadrumanes or 
 Monkeys; North America, in Herbivores; South America, in 
 Edentates; Australia, in Marsupials. 
 
 (3.) The climate of Great Britain and Europe, where 
 were the haunts of Lions, Tigers, Hippopotamuses, etc., must 
 have been warmer than now, and probably not colder than 
 warm-temperate. The climate of Arctic Siberia was such 
 that shrubs could have grown there to feed the herds of 
 Elephants, and hence could not have been below sub-frigid, for 
 which degree of cold it is possible the animals might have 
 been adapted by their hairy covering. 
 
 (4.) The meridian time of the Post-tertiary Mammals 
 was, hence, one of warmer climate over the continents than 
 the present, and much warmer than that of the Glacial 
 epoch. The species may have begun to exist before the 
 Glacial epoch ended in Europe, but belonged pre-eminently 
 to the Champlain epoch, when the lower level of the land 
 over the higher latitudes would have occasioned a warm 
 climate. 
 
 GENERAL OBSERVATIONS ON THE CENOZOIC ERA. 
 
 1. Contrast between the Tertiary and Post-tertiary periods 
 in geographical progress. The review of Cenozoic time has 
 brought out the true contrast in the results of the Tertiary 
 and Post-tertiary periods. 
 
 The Tertiary carried forward the work of rock-making 
 and of extending the limits of dry land southward, south- 
 eastward, and southwestward, which had been in progress 
 through the Cretaceous period, and, indeed, ever since the 
 Azoic age. 
 
 The Post-tertiary transferred the scene of operations to 
 the broad surface of the continent, which had been long 
 
LIFE. 235 
 
 in course of preparation, and especially to its middle and 
 higher latitudes. 
 
 Through the Tertiary the higher mountains of the globe 
 had been rising and the continents extending; and hence 
 the great rivers with their numerous tributaries which 
 are the offspring of great mountains on great continents 
 began to exist and to channel out the mountains and make 
 valleys and crested heights. In the Glacial epoch this work 
 went forward with special energy. The exposed rocks were 
 torn to fragments by the frosts and moving ice, or, in regions 
 beyond the reach of glaciers, by the torrents; the earth and 
 boulders formed were borne over the surface, and the ex- 
 cavation of valleys was everywhere in progress. In the 
 Champlain epoch, the low level at which the land lay, and 
 the gradual disappearance of the ice, enabled the flooded 
 streams to fill the great valleys deep with alluvium. In the 
 Terrace epoch, which followed, the upward movements of 
 the land terraced the alluvial deposits along the river- 
 valleys and about the lakes, and completed the action of the 
 rivers and vegetation in spreading fertility over the land. 
 
 Thus, under the rending, eroding, and transporting power 
 of fresh waters, frozen and unfrozen, the great Post-tertiary 
 agent, in connection with high-latitude oscillations of the 
 earth's crust, the surface of the earth was brought into a 
 state of preparation for the Age of Mind. 
 
 2. Life. In the Cenozoic era, as in the preceding, exter- 
 minations took place at several successive times, and were 
 followed by new creations. The Mammals of the early 
 Eocene are wholly distinct from those of the later; and 
 these were distinct from any of the Miocene, the Miocene 
 from the Pliocene, and the Post-tertiary from the Pliocene. 
 
 According to the present state of discovery, Mammals 
 commenced in the Mesozoic era, late in the Triassic period, 
 and the Mesozoic species were all Marsupials or Insectivores. 
 They were the precursor species, prophetic of that expansion 
 
 21 
 
236 ERA OF MIND. 
 
 of the new type which was to take place after the Age of 
 Reptiles had closed. In the early Eocene, at the very open- 
 ing of the Age of Mammals, appeared Herbivores and Car- 
 nivores of large size. The Herbivores were mostly Pachy- 
 derms, related to the Tapir and Hog, and distantly to the 
 Stag. The true Stag-family among Ruminants, and the 
 Monkeys, commenced in the Miocene, or possibly in the 
 later Eocene; the Elephant tribe, in the Miocene; the 
 Bovine or Ox family, in the Pliocene, or late in the Tertiary. 
 The last group seems to be more than all others especially 
 adapted to man's necessities; and it was accordingly 
 among the last of the types introduced on the globe. 
 
 V. ERA OF MIND AGE OF MAK 
 
 With the creation of Man a new era in Geological history 
 opens. In earliest time only matter existed, dead matter. 
 Then appeared life, unconscious life in the plant, conscious 
 and intelligent life in the animal. Ages rolled by, with 
 varied exhibitions of animal and vegetable life. Finally 
 Man appeared, a being made of matter and endowed with 
 life, but, more than this, partaking of a spiritual nature. The 
 systems of life belong essentially to time, but Man, through 
 his spirit, to the opening and infinite future. Thus gifted, 
 Man is the only being capable of reaching towards a know- 
 ledge of himself, of nature, or of God. He is, hence, the 
 only being capable of conscious obedience or disobedience 
 of any moral law, the only one subject to degradation 
 through excesses of appetite and violation of moral law, the 
 only one with the will and power to make nature's forces 
 his means of progress. 
 
 Man shows his exalted nature in his material structure. 
 His fore-limbs are not made for locomotion, as in all 
 
AGE OF MAN. 237 
 
 quadrupeds. They are removed from the locomotive to the 
 cephalic series, where they normally belong; for the fore- 
 limbs in Vertebrates have been shown to be strictly append- 
 ages of the occipital part of the head, although far displaced 
 in all excepting Fishes. They are fitted to serve the head, 
 and especially the intellect and soul. Man stands erect, his 
 body placed wholly under the brain, to which it is sub- 
 servient ; and his feet are simply for support and locomo- 
 tion, and not, as in the Monkeys, grasping or prehensile 
 organs for climbing. His whole outer being, in these and 
 other ways, shows forth the divine feature of the inner 
 being. And nature acknowledges with an appearance of 
 homage the spiritual element of the new age ; for the fierce 
 tribes that attend Man have but one-fourth the size in bulk 
 of those that possessed the earth in the Age of Mammals, 
 and all her departments are full of wealth and beauty for 
 Man's good. 
 
 1. Rock-deposits. 
 
 Stratified deposits of rock-material are in progress in the 
 Age of Man, as they had been in the preceding ages. They 
 occur as alluvial beds along the rivers ; as lacustrine in and 
 about lakes; as sea-border in beaches, sand-flats, shore- 
 marshes, and off-shore accumulations of earth, mud, or sand; 
 and they often contain buried shells, bones, leaves, relics 
 of the living species of the age. Rivers, and, about some 
 heights, glaciers, are at work wearing down mountain- 
 ridges and bearing the detritus to the lower lands. Ice- 
 bergs, laden with earth and stones, are floated from the 
 Arctic to the banks of Newfoundland, where they melt and 
 drop the stony material over the bottom. Marshes over 
 many parts of the continents have their accumulations of 
 vegetable debris making peat, closely imitating the forma- 
 tion of the great beds of vegetable debris of the Coal era. 
 The nature and origin of these modern deposits are con- 
 sidered under Dynamical Geology. 
 
238 ERA OF MIND. 
 
 The peculiarity of the age, as respects its rock-deposits, 
 allying it to Cenozoic time, and especially to the Post- 
 tertiary, and distinguishing it from earlier ages, is the fact 
 that its marine deposits are almost wholly confined to the 
 borders of the continents, the deposits of the interior being, 
 with a few small exceptions, of terrestrial or fresh-water 
 origin. 
 
 2, Life, 
 
 The Life of the age has the following among its charac- 
 teristics : 
 
 1. There is a vast diversity of terrestrial life. For the 
 continents have now their greatest extent and their greatest 
 variety of climates ; and hence, as life is adapted to all its 
 different conditions, this life must exceed in diversity that of 
 earlier time, especially that of all periods before the Post- 
 tertiary. As to Birds and Insects, it probably exceeds 
 greatly any earlier period in number of species, but not so as 
 to Mammals and Reptiles. In oceanic life the age may be 
 far behind the preceding ages, both in the number of species 
 of most classes and in the number of individuals under the 
 species. 
 
 2. While the Post-tertiary species of Invertebrates and 
 Plants are the same as now exist, it cannot be asserted that 
 all now living then existed. It is probable that, as the Post- 
 tertiary period drew to its close, and the present climates 
 of the globe were introduced by the movements of the 
 earth's crust in the following Terrace epoch (p. 228), there 
 were large additions of species, especially of those adapted 
 to promote Man's physical, intellectual, and moral progress, 
 through their nutritious or healing virtues, their strength 
 and beauty, and their power of multiplying the necessities 
 of labor and the evils of indolence. 
 
 3. The peculiar Mammalian life of the age appears to 
 have commenced its existence mostly in the Terrace epoch, 
 as is proved by the fact that their remains are found in 
 
AGE OF MAN. 239 
 
 ancient alluvium in the same latitudes of Europe in which 
 they now occur, or even in lower latitudes. For this shows 
 that the species were distributed over the continent very 
 much as they are now, and therefore that the climate of 
 Europe was essentially the same as now ; and this was true 
 as the Terrace epoch made progress, and not before it in 
 the Champlain epoch (p. 234). 
 
 4. The Mammals of the age have not more than one-fourth 
 the bulk of those of the Post-tertiary, the Elephants, Lions, 
 Tigers, Elk, Deer, Horses, Sloths, Kangaroos, Beavers, etc., 
 being all of much reduced size. 
 
 5. When the Mammals of the age first appeared, there 
 were still some of the great Post-tertiary Mammals in 
 existence, as the Elephant, Hhinoceros, Cave-Bear, and some 
 others, as is proved by the bones of these species occurring 
 in the same beds with those of modern animals. 
 
 The cooling climate of the progressing Terrace epoch 
 may have occasioned the final extermination of the giant 
 Post-tertiary animals. 
 
 6. Man, the dominant species of the age, adds a new class 
 of fossils to the earth's deposits. There are, besides his 
 own bones, remains of his works, as, for example, flint 
 arrow-heads and hatchets, carved wood, coins, books or 
 parchments, buried cities like Pompeii and Nineveh. 
 
 Figure 358 represents a fossil skeleton of Man from a 
 shell-rock of Guadaloupe. It is the remains of an Indian 
 killed in battle two centuries since ; and the rock is of the 
 same kind with that which is now forming and consolidating 
 on the shores. Figure 359 represents a coin-conglomerate 
 containing silver coins of the reign of Edward I., found 
 at a depth of ten feet below the bed of the river Dove in 
 England. 
 
 7. Man appears to have begun his existence in the Terrace 
 epoch, before the complete extinction of the Post-tertiary 
 Mammals; for flint arrow-heads and some other human 
 
 21* 
 
240 
 
 ERA OF MIND. 
 
 relics are found in deposits and caverns containing bones of 
 the same Post-tertiary species that are mentioned in 5, as 
 near Abbeville and Amiens in France, and at a few other 
 localities in Europe and in Britain. 
 
 8. Man is of one species. He stands alone at the summit 
 of the system of life. 
 
 He was created in the temperate zone, for the species 
 degenerates in the tropics; and in the warmer part of the 
 
 Pigs. 358, 359. 
 
 Human skeleton from Guadaloupe. Conglomerate containing coins. 
 
 temperate, because this would best suit his primitive con- 
 dition, without arts or education. 
 
 His place of origin was not on both the Occidental and 
 Oriental continents ; for no species of Mammals (excepting 
 some in the Arctic) are common to the two ; but in the 
 Orient, which was the continent of the highest of Mammals 
 through the Age of Mammals, and which thereby promised 
 to take the lead in future progress. No place of origin 
 better accords with the conditions requisite for the species in 
 
AGE OF MAN. 241 
 
 its original state and for the commencement of its develop- 
 ment than that region in western Asia, which is a central 
 point of radiation for the three great Oriental lands, Asia, 
 Europe, and Africa, where the Bible places his creation. 
 
 9. Some species of animals have become extinct since the 
 Age of Man began, and through Man's agency. The Dodo, 
 a large bird looking like an overgrown chicken in its plum- 
 age and wings, was abundant in the island of Mauritius 
 until early in the commencement of the eighteenth century. 
 The M'ottj or Dinornis, is a New Zealand bird of the Ostrich 
 kind that was living less than a century since ; it was 10 or 
 12 feet in height, and the tibia (" drumstick") 30 to 32 inches 
 long. In Madagascar remains of a still larger bird, but of 
 similar character, occur, called an JBpiornis; its egg is over 
 a foot (13 J inches) long. These are a few of the examples of 
 the modern extinction of species. 
 
 The progress of civilization tends to restrict forests and 
 forest-life to narrower and narrower limits. The Buffalo 
 once roamed over North America to the Atlantic, but now 
 lives only on the Bocky Mountain slopes west of the Mis- 
 souri Eiver. The Beaver formerly ranged over the United 
 States from the Pacific to the Atlantic, as well as to the 
 Arctic, and many of their remains occur in caverns near 
 Carlisle in Pennsylvania. It is now rarely seen east of 
 the Missouri Biver, though occasionally met with in 
 northern New York and in some parts of the Appalachians 
 to the southwest. The beaver, wolf, bear, and wild-boar 
 were formerly common in Britain, but are now wholly 
 exterminated. 
 
 3. Changes of Level. 
 
 The earth in this Age of Man its ages of progress past 
 has beyond question reached an era of comparative repose. 
 Its rocks are essentially completed j its mountains are made j 
 its great outlines, early defined, have been filled out with 
 
242 ERA OF MIND. 
 
 their various details; and, now that the system of life is 
 finished in the last creation, Man, the Earth, Man's resi- 
 dence, is also in its finished state. But yet not only is the 
 formation of rocks still in progress, the forces of nature 
 continuing to work as in former ages, but there are also 
 changes of level going on of the same kind with those of 
 past time. 
 
 These changes of level are either paroxysmal, that is, take 
 place through a sudden movement of the earth's crust as 
 sometimes happens in connection with an earthquake; or 
 they are secular, that is, result from a gradual movement 
 prolonged through many years or centuries. The following 
 are some examples : 
 
 1. Paroxysmal. In 1822, the coast of western South 
 America for 1200 miles along by Concepcion and Valpa- 
 raiso was shaken by an earthquake, and it has been esti- 
 mated that the coast near Valparaiso was raised at the 
 time 3 or 4 feet. In 1835, during another earthquake in 
 the same region, there was an elevation, it is stated, of 4 or 
 5 feet at Talcahuano, which was reduced after a while to 2 
 or 3 feet. In 1819 there was an earthquake about the Delta 
 of the Indus, and simultaneously an area of 2000 square 
 miles, in which the fort and village of Sindree were situated, 
 sunk so as to become an inland sea, with the tops of the 
 houses just out of water; and another region parallel with 
 the sunken area, 50 miles long and in some parts 10 broad, 
 was raised 10 feet above the delta. These few examples all 
 happened within an interval of sixteen years. They show 
 that the earth is still far from absolute quiet, even in this its 
 finished state. 
 
 2. Secular. Along the coasts of Sweden and Finland on 
 the Baltic there is evidence that a gradual rising of the land 
 is in slow progress. Marks placed along the rocks by the 
 Swedish government, many years since, show that the 
 change is slight at Stockholm, but increases northward, and 
 
GEOLOGICAL TIME. 243 
 
 is felt even at the North Cape, 1000 miles from Stockholm. 
 At Uddevalla the rate of elevation is equivalent to 3 or 4 
 feet in a century. 
 
 In Greenland, for 600 miles from Disco Bay, near 69 N., 
 to the firth of Igaliko 60 43' N., a slow sinking has been 
 going on for at least four centuries. Islands along the coast, 
 and old buildings, have been submerged. The Moravian 
 settlers have had to put down new poles for their boats, and 
 the old ones stand " as silent witnesses of the change." 
 
 It is suspected that a sinking is also in progress along the 
 coast of New Jersey, Long Island, and Martha's Vineyard, 
 and a rising in different parts of the coast-region between 
 Labrador and the Bay of Fundy. There are deeply buried 
 stumps of forest-trees along the seashore plains of New 
 Jersey, whose condition can hardly be otherwise explained. 
 
 The above cases illustrate movements by the century, or 
 those slow oscillations which have taken place through the 
 geological ages, raising and sinking the continents, or at 
 least changing the water-line along the land. 
 
 This fact is to be noted, that these secular movements of 
 the Age of Man are, so far as observed, high-latitude oscilla- 
 tions, just as they were in the Post-tertiary period ; and they 
 indicate, therefore, that the Post-tertiary system of changes 
 has not yet reached its final end. 
 
 GENEEAL OBSERVATIONS ON GEOLOGICAL 
 HISTORY. 
 
 1. LENGTH OF GEOLOGICAL TIME. 
 
 By employing as data the relative thickness of the form- 
 ations of the Geological ages, estimates have been made of 
 the time-ratios of those ages, or their relative lengths (pp. 
 145, 198). These estimated time-ratios for the Paleozoic, 
 
244 HISTORICAL GEOLOGY. 
 
 Mesozoic, and Cenozoic are 14 : 4 : 3, equivalent to 3 : 1 : f ; 
 that is, Paleozoic time was 3 times as long as the Meso- 
 zoic, and the Cenozoic was three-fourths as long. But the 
 numbers may be much altered when the facts on which 
 they are based are more correctly ascertained. There is no 
 doubt that the Paleozoic era exceeded the Mesozoic in length 
 3 or 4 times, and probably was full twice as long as the Meso- 
 zoic and Cenozoic united. It is also quite certain that the 
 first of the Paleozoic ages the Silurian was at the least 
 three times as long as either the Devonian or Carbonif- 
 erous. 
 
 Hence comes the striking conclusion that the longest age 
 of the world since life began was the earliest, when the 
 earth was even without fishes and numbered in its popula- 
 tion only Radiates, Mollusks, and marine Articulates. And 
 the time of the earth's beginnings before the introduction 
 of life may have exceeded in length all subsequent time. 
 
 The actual lengths of these ages it is not possible to deter- 
 mine even approximately. All that Geology can claim to 
 do is to prove the general proposition that Time is long. 
 
 One of the means of calculation which have been appealed 
 to is that afforded by the Falls of Niagara. The river 
 below the Falls flows northward in a deep gorge, with high 
 rocky walls, for seven miles, towards Lake Ontario. It is 
 reasonably assumed that the gorge has been cut out by the 
 river, for the river is annually making progress of this very 
 kind. From certain fossiliferous Post-tertiary beds over the 
 country bordering the present walls, it is proved that the 
 present gorge, about six miles long, was not made before 
 the Glacial epoch. The present annual progress of the 
 gorge from the cutting and undermining action of the 
 waters has been variously estimated from three feet a century 
 to one foot a year. At the larger estimate of one foot a year, 
 the six miles would have required 31,000 years; and if the 
 estimate be one inch a year, or 8^ feet a century, the time 
 
PROGRESS OF LIFE. 245 
 
 becomes nearly 380 ; 000 years. Since one foot a year is 
 proved by observation to be altogether too large an esti- 
 mate, the calculation may be regarded as at least esta- 
 blishing the proposition that Time is long, although it affords 
 no satisfactory numbers. 
 
 Other modes of calculation fully establish this general 
 proposition. Some estimates which have been recently 
 made seem to show that it is true even of the Age of Man; 
 but they are based on too imperfect a knowledge of facts to 
 be of value. 
 
 2. GEOGRAPHICAL PROGRESS IN NORTH AMERICA. 
 
 The principal steps of progress in the continent of North 
 America are here recapitulated : 
 
 1. The continent at the close of the Azoic lay spread out 
 mostly beneath the ocean (map, p. 73). Although thus sub- 
 merged, its outline was nearly the same as now. The dry land 
 lay mostly to the north, as shown in the map. The form 
 of the main mass approximated to that of the letter V, and 
 it had a southeast and a southwest border nearly parallel to 
 its present outline. 
 
 2. Through the Paleozoic ages, as the successive periods 
 passed, the dry land gradually extended itself southward in 
 consequence of a gradual elevation : that is, the sea-border 
 at the close of the Lower Silurian was as far south as the 
 Mohawk valley in New York ; at the close of the Upper 
 Silurian it extended along not far from the north end of 
 Cayuga Lake and Lake Erie; and by the close of the Devo- 
 nian age the State was a portion of the dry land nearly to 
 its southern boundary. This progress southward of the sea- 
 border in New York may be taken as an example of what 
 occurred along the borders of the Azoic to the westward. 
 In other words, there was through the Silurian and Devo- 
 nian ages a gradual southerly extension of the dry part of 
 the continent, that is, to the southeastward and the south- 
 westward. 
 
24G HISTORICAL GEOLOGY. 
 
 By the close of the Carboniferous age, or before the open- 
 ing of the Mesozoic era, the dry portion appears to have so 
 far extended southwardly as to include nearly all the area 
 east of the Mississippi and north of the Gailf States, along 
 with a part of that west of the Mississippi, as far nearly as 
 the western boundary of Kansas. 
 
 3. Before the Silurian age began, and in its first period, 
 great subsidences were in progress along the Lake Superior 
 region, when the thick Huronian and Potsdam formations 
 were made. The facts show that the depression of the lake, 
 and probably that of some of the other great lakes, and 
 also that of the river St. Lawrence, began to form either 
 during the closing part of the Azoic age or in the early 
 part of the Silurian age. 
 
 4. During the Paleozoic ages, rock-formations were in 
 progress over large parts of the submerged portions of the 
 continent up to the sea-borders, and some vast accumula- 
 tions of sand were made as drifts or dunes over the flat 
 shores and reefs. These rock-formations had in general ten 
 times the thickness along the Appalachian region which 
 they had over the interior of the continent ; and they were 
 mostly fragmental deposits in the former region, while mostly 
 limestones in the latter. Hence two important conclusions 
 follow : 
 
 First. The Appalachian region was through much of the 
 time an exposed shore-reef or flat of great extent, parallel 
 in course with the present sea-border as well as that of the 
 ancient Azoic; while the interior was a shallow sea opening 
 southward freely into the Gulf of Mexico, and only during 
 some few of the periods with the same freedom eastward 
 directly into the Atlantic. Most of the western part of the 
 sea (west of Missouri) appears to have been too deep for de- 
 posits between the Lower Silurian and Carboniferous eras. 
 
 Secondly. The Appalachian region was undergoing, 
 through the Silurian and Devonian ages, great changes of 
 
PROGRESS OP LIFE. 247 
 
 level, and the amount of subsidence involved exceeded by 
 ten times that in the Interior Continental region. 
 
 5. Of this Appalachian region, some or all of the Green 
 Mountain portion was elevated above the ocean's level at 
 the close of the Lower Silurian; and at the same time the 
 valley of Lake Champlain and Hudson Elver was formed 
 or began. 
 
 This valley and the depressions of the Great Lakes, arid 
 also those of the lakes extending in a line through British 
 America northwestward from Lake Superior to the Arctic, 
 lie not far from the borders of the Azoic continent, and, 
 therefore, between the portion of the continent that was 
 comparatively stable dry land from the time of the Azoic 
 onward, and that portion which was receiving rock-forma- 
 tions and undergoing oscillations of level. To this they 
 owe their origin. 
 
 6. As the Paleozoic era closed, an epoch of revolution 
 occurred, in which the rocks of the Appalachian region and 
 those of the Eastern border underwent (1) great changes of 
 level ; (2) extensive flexures or foldings ; (3) immense fault- 
 ings in some parts ; (4) consolidation, and, in the eastern 
 half especially, crystallization or metamorphism on a grand 
 scale, and the loss of bitumen by the cOal-beds changing 
 them into anthracite. These changes affected the region 
 from Labrador to Alabama. The effects Of heat and uplift 
 were more decided toward the Atlantic than toward the 
 interior, showing that the force producing the great results 
 was exerted in a direction from the Atlantic inland, or 
 from the southeast toward the northwest. The Appa- 
 lachian Mountains were then made; and they were, con- 
 sequently, in existence when the Mesozoic era opened. 
 
 These mountains are parallel to the eastern outline of the 
 original Azoic continent. The outline of the New York 
 Azoic peninsula is repeated in the trend of the Appalachian 
 chain along through western New England and Pennsyl- 
 
 22 
 
248 HISTORICAL GEOLOGY. 
 
 vania (the direction in New England being nearly north and 
 south and in Pennsylvania as nearly east and west), and it 
 is again repeated in the eastern and southern coasts of New 
 England. 
 
 Similar changes may have taken place on the Pacific side; 
 but facts proving this have not yet been collected. 
 
 The epoch of revolution was equally revolutionary in 
 Europe. No living species are known to have survived from 
 the Paleozoic into the Mesozoic. 
 
 . 7. In the early or middle Mesozoic period (the continent 
 being largely dry land, as stated in the latter part of 2), 
 long depressions in the surface of the continent, made in the 
 course of the Appalachian revolution and situated between 
 the Appalachians and the sea-border, were brackish-water 
 estuaries, or were occupied by fresh-water marshes and 
 streams ; and Mesozoic sandstone, shale, and coal-beds were 
 formed in them. The Connecticut valley region of Mesozoic 
 rocks (p. 164) is one example. At the same time there were 
 formations in progress over the Eocky Mountain region, a 
 vast area from which the sea was not excluded, or only 
 in part : the shores of this Mesozoic interior sea appear to 
 have extended through Kansas near the meridian of 20 
 west of Washington (97 west of Greenwich). 
 
 8. In the later Mesozoic, or the Cretaceous period, the 
 continent had its Atlantic and Gulf border yet under water, 
 and Cretaceous rocks were formed about them, and thus the 
 continent continued its former course of enlargement south- 
 eastward (see map, p. 196). The Western Interior sea, open- 
 ing south into the Gulf of Mexico, just alluded to, still 
 existed, and deposits were made in it over a very large part 
 of the great region reaching from Kansas on the east to the 
 Colorado on the west. The Pacific border was also receiv- 
 ing an extension like the Atlantic. 
 
 9. In the early Cenozoic, or Tertiary period, the exten- 
 sion of the Atlantic and Pacific borders was stiil continued. 
 
PROGRESS OF LIFE. 249 
 
 With its close the progress of the continent in rock-making 
 southeastward and southwestward was very nearly com- 
 pleted. 
 
 The Western Interior sea had become greatly contracted 
 after the Cretaceous period by the elevation of the Rocky 
 Mountain region; and, although the Mexican Gulf still 
 remained of more than twice its present area, it was much 
 reduced in size (map, p. 217). At the beginning of the 
 Tertiary period the Ohio and Mississippi reached an arm of 
 the Gulf just where they join their waters ; at its close the 
 Ohio had taken a secondary place as a tributary of the 
 Mississippi. The great Missouri River, the real trunk of 
 the Interior river-system rather than the Mississippi, began 
 its existence after the Cretaceous period, and reached its 
 full size only towards the close of the Tertiary, when the 
 Rocky Mountains had finally attained their full height. 
 
 10. The elevation of the Rocky Mountains, like that of 
 the Appalachians, was the raising of the land along a region 
 parallel with the outline of the original Azoic continent 
 (see map, p. 73). The elevation of the Cascade range of 
 Oregon and Sierra Nevada of California was a doubling of 
 this same line on the west ; while the elevation of the trap 
 ridges and red sandstone of the early Mesozoic along the 
 Atlantic border (p. 165) was a doubling of the line on the 
 east. 
 
 11. The continent being thus far completed, as the Post- 
 tertiary period was drawing on, operations changed from 
 those causing southern extension to those producing move- 
 ments of ice and fresh waters over the land, especially in 
 the higher latitudes ; and thereby valleys, great and small, 
 were excavated over the continent ; earth and gravel were 
 transported and made to cover deeply the rocks and spread 
 the continent with fertile plains and hills ; and, as the final 
 result, those grand features and those qualities of surface 
 
250 HISTORICAL GEOLOGY. 
 
 were educed that were requisite to make the sphere a fit 
 residence for Man. 
 
 3. PROGRESS OF LIFE. 
 
 From the survey of the Life of the globe which has been 
 made, the following conclusions may be drawn. Future 
 discovery may change some of the details; but it is not 
 probable that it will aifect the general principles announced. 
 
 1. Fact of progress of life. Life commenced among plants 
 in Sea-weeds ; and it ended in Palms, Oaks, Elms, the Orange, 
 Rose, etc. It commenced among animals in Lingulce (Mol- 
 lusks standing on a stem like a plant) and in Crinoids and 
 Trilobites, if not earlier in the simple systemless Protozoans 
 (p. 58) ; it ended in Man. Sea-weeds were followed by 
 Ferns and other Flowerless plants, and by G-ymnosperms, 
 the lowest of Flowering plants j these finally by the higher 
 Flowering species above mentioned, the Palms and Angio- 
 sperms. Radiates, Mollusks, and Articulates of the Silurian 
 afterwards had Fishes associated with them; late?, Reptiles; 
 later, Birds and inferior Mammals; later, higher Mammals, as 
 Beasts of prey and Cattle; lastly, Man. 
 
 2. Progress from marine , to terrestrial life. The Silurian 
 and Devonian were eminently the marine ages of the world. 
 The plants of the Silurian are sea-weeds, and the animals all 
 marine. The animals of the Devonian, also, are mainly 
 marine; but there is a step taken in terrestrial life by the 
 introduction of land-plants and Insects. 
 
 In the Carboniferous age and through the Mesozoic era 
 the continents, or large areas over them, underwent alter- 
 nations between a submerged state and dry land, leading a 
 kind of amphibian existence. The Carboniferous age had,, 
 besides aquatic life and Insects, its terrestrial Mollusks and 
 Centipedes, its Amphibian and other Eeptiles, besides a 
 great profusion of forest-trees and other terrestrial vegeta- 
 
PROGRESS OF LIFE. 251 
 
 tion. In the early Mesozoic, to Eeptiles were added Birds 
 and Mammals, eminently terrestrial kinds of life. 
 
 The Cenozoic was distinctively a continental era. The 
 continents became mostly dry land after its earliest epoch; 
 and as the Age of Man approached, they had their full size 
 and their present diversities of surface and climate. With 
 the increased variety of conditions fitted for terrestrial life 
 there was, beyond question, a great augmentation in the 
 number and variety of terrestrial species. Mammals were 
 most numerous in kinds in the Post-tertiary; but Birds and 
 Insects have probably their greatest numbers and variety 
 of species in the present age. Marine species still abound, 
 but relatively to the terrestrial they are far less numerous 
 and less extensively distributed than in the Mesozoic and 
 earlier ages. 
 
 3. Progress was connected with a constant change of life by 
 exterminations and the introduction of new species. No species 
 of animal survived from the beginning of life on the globe 
 to the present time, nor even through a single one of the 
 several geological ages ; and but few lived on from the 
 beginning of any one of the many periods to its close, or 
 from one period to another. 
 
 There were universal exterminations, according to the 
 existing state of testimony (with perhaps an exception as 
 regards some species of oceanic x life, p. 203), closing some of 
 the ages, as the Carboniferous and the Reptilian ; there were 
 exterminations, nearly as complete, closing the periods on 
 each of the continents ; and others, usually less complete,- 
 closing epochs ; and often some exterminations accompany- 
 ing each change in the rock-depositions that were in pro- 
 gress. For, in passing from one bed to another above, some 
 fossils fail that occur below; and from the strata of one 
 epoch to another, still larger proportions disappear; and 
 sometimes with the transitions to rocks of another period 
 or age, all the species are different. 
 
 22* 
 
252 HISTORICAL GEOLOGY. 
 
 Of all genera of animals now having living species, only 
 two (and those Molluscan, Lingula and Discina) commenced 
 their existence in the earliest Silurian; every other genus 
 of that early time sooner or later numbered only extinct 
 species. 
 
 Such unbroken lines prove the oneness of plan or system 
 through geological history, and, therefore, of purpose in the 
 Creator. 
 
 Five hundred species of Trilobite lived in the course of 
 the Paleozoic ages : afterward there were none. 900 
 species of the Ammonite group existed in the Mesozoic, 
 not all at once, but, as in the case of the Trilobites, in a 
 succession of genera and species : the last then disappeared. 
 There have been 450 species of the Nautilus tribe in exist- 
 ence : now there are but 2 or 3, and these are peculiar to 
 the present age. 700 species of Ganoids have been found 
 fossil: the tribe is now nearly extinct. The remains of 
 2500 species of plants and nearly 40,000 species of animals 
 have been found in the rocks, not one of which is now in 
 existence. These are a few examples of the extinctions of 
 tribes that have taken place. But the number of kinds of 
 fossils discovered cannot be the number of species that 
 have existed; and the above numbers of marine species 
 may safely be multiplied by three, and of terrestrial by 
 twenty. 
 
 The facts show that the life of the world underwent con- 
 stant changes through exterminations and creations. 
 
 4. Progress not always begun by the introduction first of the 
 lowest species of a group. Mosses, although inferior to Ferns, 
 appear to have been of later introduction, for no remains 
 have been found in the Carboniferous or Devonian rocks, 
 in which rocks there are relics of both Ferns and Gymno- 
 sperms. 
 
 The earliest of Fishes, instead of being 'those of lowest 
 grade, were among the highest : they were Ganoids, or rep- 
 
PROGRESS OF LIFE. 253 
 
 tilian Fishes (that is, a kind intermediate in some respects 
 between Fishes and Reptiles), along with others of the 
 order of Selachians or Sharks, the superior division of the 
 class. Trilobites of the first fauna of the Silurian are not 
 the lowest of Crustaceans. No fossil Snakes have been 
 found below the Cenozoic, although large Eeptiles abounded 
 in the Mesozoic. Oxen date from the later Tertiary, long 
 after the first appearance of many higher Mammals, as 
 Tigers, Dogs, Monkeys, etc. 
 
 There was upward progress in the grand series of species, 
 as stated in 1, but there was not progress in all cases from 
 the lowest species to the highest. 
 
 5. The earliest species of a group were often those of a com- 
 prehensive type. The Ganoid fishes are an example of 
 these comprehensive types. As stated on page 111, they 
 were intermediate between Fishes and Reptiles; they were 
 fishes comprehending in their structure some Reptilian cha- 
 racters, and hence called comprehensive types. 
 
 The Selachians are another example of a comprehensive 
 type ; for the sharks have some important peculiarities in 
 which they approximate to the higher Vertebrates and even 
 Mammals, as is seen in their mode of development and in 
 the very small number of their young. 
 
 Fishes commenced with these two comprehensive types, 
 the Ganoid and Selachian. 
 
 The earliest Mammals were Marsupials, or species of 
 Mammals comprehending in their structure some character- 
 istics of oviparous Mammals (see p. 50), and, therefore, in 
 certain respects intermediate between Mammals and Ovipa- 
 rous Vertebrates. 
 
 The vegetation of the coal era included trees allied to the 
 small Ground-pine or Lycopodia of the present day; and 
 these, as well as the Lycopodia, constitute a type interme- 
 diate in some points between Ferns and Pines or Conifers 
 (p. 108). There were at the same time Sigillarise, a type 
 
254 HISTORICAL GEOLOGY. 
 
 allied closely to the Pine tribe, but intermediate between it 
 and the Lycopodia and Ferns. 
 
 In the Mesozoic the most characteristic plants were 
 Cycads; and these comprehended in their structure some- 
 thing of three distinct types. They are most closely like 
 Conifers in fruit ; but they are like Ferns in the way the 
 leaves unfold, and in some other points, and like Palms in 
 their habit of growth and their foliage (p. 167). 
 
 These comprehensive types embraced in their natures 
 usually the features of some type that was to appear in the 
 future. Thus, the Ganoid fishes of the Devonian in a sense 
 foreshadowed the type of Reptiles, the species under which 
 did not come into existence until long afterward in the 
 Carboniferous age. The Cycads in a similar manner fore- 
 shadowed the Palms, a type which $id not appear until the 
 Cretaceous period. 
 
 6. Harmony in the life of a period or age. Through the 
 existence of these comprehensive types, and also in other 
 ways, there was always a striking degree of harmony 
 between the species making up the population or the 
 fauna and flora of each period in the world's history. 
 
 Among the plants of the Carboniferous age there were 
 (1) the highest of the Cryptogams, or Flowerless plants, the 
 Ferns; (2) the lowest of Phenogams (Gymnosperms), or 
 Flowering plants, species having only inconspicuous and 
 imperfect flowers, and hence almost flowerless ; and (3) the 
 intermediate types of Lycopodia (Lepidodendra) and Sigil- 
 larise. 
 
 Again, in the Mesozoic the terrestrial Yertebrate life 
 included (1) Reptiles, which are oviparous species; (2) 
 Birds, also oviparous species ; (3j reptilian Birds, having long 
 tails like the Reptiles, a comprehensive type; (4) Insect- 
 ivorous (Insect-eating) Mammals; (5) semi-oviparous Mam- 
 mals, or Marsupials, an intermediate type between the true 
 Insectivores and the oviparous Reptiles and Birds. 
 
PROGRESS OP LIFE. 255 
 
 This kind of harmony existed in all the ages. 
 
 It exists none the less now when the types have their 
 widest diversity; for the less size of the brute beasts 
 than in the Post-tertiary, remarked upon on page 239, and 
 the reference throughout the Flora and Fauna of the world 
 to Man, are in full harmony with the spiritual being at 
 the head of the existing creation. 
 
 7. Progress always the gradual unfolding of a system Man 
 the culmination of that system. There were higher and lower 
 species created through all the ages, but the successive 
 populations were still, in their general range, of higher and 
 higher grade ; and thus the progress was ever upward. The 
 type or plan of vegetation, and the four grand types or 
 plans of animal life (the Eadiate, Molluscan, Articulate, 
 and Yertebrate), ordained in the act of creation, were each 
 displayed under multitudes of tribes and species, rising in 
 rank with the progress of time, and all under relations so 
 harmonious and so systematic in their successions that they 
 seem like the expression in material living forms of one 
 divine idea. 
 
 With every new fauna and flora in the passing periods, 
 there was a fuller and higher exhibition of the kingdoms 
 of life. Had progress ceased with the Post-tertiary, when 
 the world was given up to brute passion and ferocity, the 
 system might have been pronounced the scheme of an evil 
 demon. But, as time moved on, Man came forth, not in 
 strength of body, but in the majesty of his spirit; and then 
 living nature was full of beneficence. The system of life, 
 about to disappear as a thing of the past, had its final pur- 
 pose fulfilled in the creation of a spiritual being, one hav- 
 ing powers to search into the depths of nature and use the 
 wealth of the world for his physical, intellectual, and moral 
 advancement, that he might thereby prepare, under divine 
 aid, for the new life in the coming future. 
 
 Thus, through the creation of Man completing the system 
 
256 HISTORICAL GEOLOGY. 
 
 of life, all parts of that system became mutually consistent 
 and full of meaning, and Time was made to exhibit its true 
 relation to Eternity. 
 
 Methods of exterminations of species and extinctions of tribes. 
 (1.) Some species of plants and animals require dry land 
 for their support and growth ; some, fresh-water marshes or 
 lakes; some, brackish water; some, seashore or shallow 
 marine waters ; some, deeper ocean-waters. 
 
 Hence, (a) movements in the earth's crust submerging 
 large continental areas, or raising them from the condition 
 of a sea-bottom to dry land, would exterminate life : sink- 
 ing them in the ocean, extinguishing terrestrial life, raising 
 them from the ocean, extinguishing marine life. In early 
 times, when the continental surface was in general nearly 
 flat, a change of level of a few hundred feet, or perhaps of 
 even 100, would have been sufficient for a wide extermi- 
 nation. If a modern coral island were to be raised 150 feet, 
 its reef-forming corals would all be killed ; or if sunk in the 
 ocean 150 feet, the same result would follow, because the 
 species do not grow below a depth of 100 feet. And if all 
 the coral-reefs of the Pacific were simultaneously sunk or 
 raised to the extent stated, there would be a total extinction 
 of a large number of species. 
 
 (&) Along a seacoast the bays and inlets sometimes 
 are closed by barriers thrown up by the sea, and hence 
 become fresh, killing all marine life. Again, barriers are 
 often washed away by the sea, and then salt water enters, 
 destroying fresh-water life. 
 
 (2.) Species are also made for a limited range of tempera- 
 tures : some, for the equatorial regions only; some, for the 
 cooler part of the tropical zone; some, for the warmer 
 temperate latitudes; some, for the middle temperate; 
 some, for the colder temperate ; some, for the frigid zone ; 
 and few species live through two such zones. 
 
PROGRESS OF LIFE. 257 
 
 Hence, (a) as the earth has gradually cooled in its 
 climates from a time of universal tropics to that of the 
 present condition, those tribes or families made for the 
 earlier condition of the globe afterward became of necessity 
 extinct. This may be a reason why many of the tribes of 
 the ancient world disappeared, and why the Eeptilian type 
 culminated in the Mesozoic ; these species were made espe- 
 cially for the warm condition which then prevailed. 
 
 Again, (>) any temporary change of climate over the 
 globe from cold to warm or warm to cold would have 
 exterminated species. An increase in the extent and height 
 of Arctic lands would have increased the cold, as shown by 
 Lyell, and thereby sent cold winds south over the conti- 
 nents and cold oceanic currents south along the border of 
 the oceans. 
 
 On the contrary, a diminution in the extent of Arctic 
 lands, making the higher regions open seas, or an increase 
 in the extent of tropical lands for the sun to heat, would 
 have increased the heat of the globe and sent a warm 
 climate far north. 
 
 Such changes are destructive- to living species. It is sug- 
 gested on p. 204 that the destruction of life at the close of 
 
 O -L 
 
 the Mesozoic may have arisen from the cause here explained. 
 
 (3.) The heat which has escaped from the earth's interior 
 through the crust, in connection with igneous eruptions, or 
 seasons of metamorphic changes when the earth's rocks 
 were crystallizing on a vast scale, would have caused a 
 destruction of all marine life in the vicinity; and where 
 metamorphic action has taken place through an area a thou- 
 sand miles or more in length, as in the progress of the 
 Appalachian revolution (p. 155), the devastation must have 
 extended over a large part of the continental area. 
 
 Origination of species. Geology affords no support to the 
 hypothesis that species have been made from pre-existing 
 
258 HISTORICAL GEOLOGY. 
 
 species, and suggests no theory of development by natural 
 causes. In other words, it has no facts sustaining the notion 
 that Man was made through the gradual progress or im- 
 provement of some one of the Apes, or by any method of 
 development out of an Ape, or that Elephants were so made 
 from Mastodons, or the reverse, or from any other species, 
 or one species of Monkey, Cat, Horse, etc., from another; and 
 much less does it favor the hypothesis that the whole sys- 
 tem of animal life is nothing but a growth from one, two, 
 or more original species, one changing into, or evolving, 
 another, through a method of development, as supposed in 
 a development-hypothesis. The facts the science has thus 
 far collected prove that a system of life has been gradually 
 brought out in the course of the ages. But it gives no 
 information, in the author's opinion, as to the manner in 
 which the Divine will called into existence the successive 
 tribes or species. 
 
 The science in its present state affords the following evi- 
 dence bearing on this subject : 
 
 1. Species do not shade into one another as if they had 
 originated by transitions from one another. For example, 
 the Post-tertiary Mastodon and Elephant of J^orth America 
 do not pass into one another or into other earlier species; 
 or the Apes into the species Man ; or any Mollusks or Articu- 
 lates, through a series of stages, into Fishes; or any Sea- 
 weeds into Ferns or the earliest land-plants, etc. The spe- 
 cies of plants and animals at the present day as well as 
 those of the past, with comparatively few exceptions, have 
 their limits well defined, and do not blend with one another 
 by insensible gradations. 
 
 2. Groups commence sometimes in their higher species. 
 Thus, Fishes the earliest of Vertebrates began with the 
 Ganoids and Sharks, with no evidence of a progress upward 
 from lower species. The first of Land-plants are the Ferns, 
 
PROGRESS OF LIFE. 259 
 
 Lepidodendra, etc. ; and no species of the inferior group of 
 Mosses have been found marking a line of progress upward 
 to the Lepidodendra. Many other such cases might be men- 
 tioned. 
 
 3. The earth's progress has involved the occurrence at 
 intervals of revolutions or devastations. Some of these 
 devastations appear to have been nearly or quite universal 
 over the globe, while others have been confined to single 
 continents, or limited areas, and have been only partial (see 
 p. 162). But, whether universal or not, they have often cut 
 off short not only species, but genera, families, and tribes; and 
 yet the same genera, families, and tribes have had new 
 species afterwards. Life has been re-introduced where it 
 had been exterminated, as if the system were not at the 
 mercy of temporary catastrophes, but owed its restoration 
 and continued progress to a power that was independent of 
 all causes of desolation and could even use desolation as a 
 means of progress. 
 
 The advocates of a development-hypothesis do not deny 
 the above evidence; but they argue that the records are 
 very imperfect, full of long breaks; and, again, that only a 
 small part of the world has been searched for its truths, and 
 that part not thoroughly. 
 
 Eut a hypothesis unsustained by facts just where it would 
 be most natural to look for them, and resting for its geolo- 
 gical basis on possible discoveries in the future, may well be 
 left to pass as a mere suggestion until the discoveries have 
 been made. This is the dictate of true Science. 
 
 Geology has no theory of creation to present; and its 
 discoveries are already so extensive, and so corroborative of 
 the general results arrived at, from whatever continent they 
 have been gathered, that its present silence is in weighty 
 opposition to such views. The science testifies to the fact 
 that plants and animals have come into existence in a long 
 
 23 
 
260 HISTORICAL GEOLOGY. 
 
 succession of species. It demonstrates the oneness in plan 
 and purpose of all nature, and thereby the oneness of its 
 Author. It points to boundless wisdom in every step of 
 progress, and with increasing distinctness as the era ap- 
 proaches when Man should appear and receive the Divine 
 command, " Subdue and have dominion." But it directs 
 to no cause of the origin of species but the Cause of causes, 
 the infinite God. 
 
 In the account of creation given in the first chapter of 
 Genesis, it is stated that on the fifth day the waters brought 
 forth abundantly the moving creature that hath life, the 
 flying creatures of the air, and the great whales (a word 
 meaning as truly reptiles). In the commencing Silurian 
 the first appearance of the swarming life of the waters took 
 place (p. 93). In the Devonian, Fishes and Insects were 
 added ; in the Carboniferous, Reptile life began j and in the 
 Mesozoic, Birds as well as Eeptiles existed, and the latter 
 became the dominant life of the globe. At the same time, 
 small semi-oviparous Mammals, or Marsupials, with probably 
 some Insectivores, appeared as precursors of the age that 
 was next to follow. With the close of the Mesozoic the 
 Reptile world ended; and so ended also the fifth day of the 
 Mosaic record. 
 
 On the sixth day there were two great works, first, the 
 creation of Mammals, and, as a second, the creation of Man. 
 
 With the opening Cenozoic, Mammals came forth in 
 great numbers and of large size ; and as the era advanced, 
 they increased in variety until the type reached an expan- 
 sion as to magnitude of individuals and numbers of kinds 
 even exceeding the exhibition of it in the present age. 
 Thus passed the first portion of the sixth day. Finally 
 Man appeared as the last great work. 
 
 Creation finished, the day of rest followed, the era of 
 
PROGRESS OF LIFE. 261 
 
 the finished world, the era also of Man's progress and pre- 
 paration for another and a higher life. And as the " six 
 days" work of creation is succeeded by a seventh of rest, 
 so, it has been well said, the Sabbath closes man's week, as 
 a day of rest and of preparation for that spiritual life. 
 
PART IV. 
 
 DYNAMICAL GEOLOGY. 
 
 DYNAMICAL GEOLOGY treats of the causes or origin of 
 events in Geological history, that is, of the origin of rocks, 
 of disturbances of the earth's strata, and their effects, 
 of valleys, of mountains, of continents, and of the 
 changes in the earth's features, climates, and living species. 
 
 The agencies of most importance, next to the universal 
 power of Gravitation, are Life, the Atmosphere, Water, Heat, 
 and Cohesive and Chemical attraction. 
 
 The following are the subdivisions of the subject here 
 adopted: 1. Life; 2. The Atmosphere; 3. Water; 4. Heat 
 the mechanical effects of the Atmosphere, "Water, and 
 Heat being considered under these heads ; 5. Movements in 
 the earth's crust, and their consequences, including the fold- 
 ing and uplifting of strata, the production of earthquakes, 
 and the origin of mountains and of the earth's general 
 features. Chemical Geology, which treats of the chemical 
 operations connected with the origin of rocks, constitutes 
 another division of the subject, but is not here taken up. 
 
 I. LIFE. 
 
 Life has done much geological work by contributing mate- 
 rial for the making of rocks. Nearly all the limestones of 
 
 262 
 
PEAT-FORMATIONS. 263 
 
 the globe, all the coal, and some siliceous beds, besides por- 
 tions of rocks of other kinds, have been formed out of the 
 stony relics of living species. 
 
 Through simple growth and the power of secretion, Ver- 
 tebrates form a bony skeleton ; Mollusks make shells, which 
 are calcareous, or nearly of the composition of common 
 limestone; Polyps make Corals, also calcareous; Crinoids 
 make stems and flower-like skeletons that are calcareous ; 
 and the Polyps and Crinoids, although as really animal as 
 any quadruped, are yet so low in organization that nine- 
 tenths of the bulk of the animal are often stony (calca- 
 reous), and still the functions of life are perfectly carried on. 
 
 There are various kinds, also, of microscopic species 
 which contribute to the material of rocks. The Ehizopods 
 among animals (p. 59) make calcareous shells, each con- 
 taining one or many minute cells; the Diatoms among 
 microscopic plants (p. 61) make siliceous shells ; the Poly- 
 cystines among microscopic animals make siliceous shells. 
 
 Plants also make beds of coal and peat out of accumula- 
 tions of leaves and stems, as already in part explained on 
 page 135. 
 
 In further illustration of this subject, three examples of 
 rock-making may be described: I. Peat-formations; 2. 
 Beds of microscopic organisms; 3. Coral-reefs. 
 
 1. Peat-formations. 
 
 Peat is an accumulation of half-decomposed vegetable 
 matter formed in wet or swampy places. In temperate 
 climates it is due mainly to the growth of mosses of the 
 genus Sphagnum. These mosses form a loose turf; and, as 
 they have the property of dying at the extremities of the 
 roots while increasing above, they may gradually form a bed 
 
 23* 
 
264 DYNAMICAL GEOLOGY. 
 
 of great thickness. The roots and leaves of other plants, 
 or their branches and stumps, and any other vegetation 
 present, may contribute to the accumulating bed. The car- 
 casses and excrements of dead animals at times become 
 included. Dust may also be blown over the marsh by the 
 winds. 
 
 In wet parts of Alpine regions there are various flowering 
 plants which grow in the form of a close turf, and give rise 
 to beds of peat like the moss. In Fuegia, although not 
 south of the parallel of 56, there are large marshes of such 
 Alpine plants, the mean temperature being about 40 F. 
 
 The dead and wet vegetable mass slowly undergoes a 
 change, becoming an imperfect coal, of a brownish-black 
 color, loose in texture, and often friable, although com- 
 monly penetrated with rootlets. In the change the woody 
 fibre loses a part of its gases ; but, unlike coal, it still con- 
 tains usually 25 to 33 per cent, of oxygen. Occasionally it 
 is. nearly a true coal. 
 
 Peat-beds cover large surfaces of some countries, and 
 occasionally have a thickness of forty feet. One-tenth of 
 Ireland is covered by them ; and one of the " mosses" of the 
 Shannon is stated to be fifty miles long and two or three 
 broad. A marsh near the mouth of the Loire is described 
 by Blavier as more than fifty leagues in circumference. 
 Over many parts of New England and other portions of 
 North America there are extensive beds. The amount in 
 Massachusetts alone has been estimated to exceed 120,000,000 
 of cords. Many of the marshes were originally ponds or 
 shallow lakes, and gradually became swamps as the water, 
 from some cause, diminished in depth. The peat is often 
 underlaid by a bed of whitish shell marl, consisting of fresh- 
 water shells mostly species of Cyclas and Planorbis 
 which were living in the lake. There are often also beds 
 of the siliceous shields of Diatoms. 
 
 Peat is used for fuel and also as a fertilizer. When pre- 
 
BEDS OF MICROSCOPIC ORGANISMS. 265 
 
 pared for burning, it is cut into large blocks and dried in 
 the sun. It is sometimes pressed in order to serve as fuel 
 for steam-engines. Muck is another name of peat, and is 
 used especially when the material is employed as a manure ; 
 but it includes also impure varieties not fit for burning, 
 being applied to any black swamp-earth consisting largely 
 of decomposed vegetable matter. 
 
 Peat-beds sometimes contain standing trees, and entire 
 skeletons of animals that had sunk in the swamp. The 
 peat-waters-have often an antiseptic power, and flesh is 
 sometimes changed by the burial into adipocere. 
 
 2. Beds of Microscopic Organisms. 
 
 Microscopic life abounds in almost all waters, especially 
 over muddy bottoms, as in lakes, rivers, marshes, salt- 
 water swamps, harbors, bays, the shallow borders of the 
 ocean, and also the deep ocean. Part of the species make 
 no stony secretions, but much the larger part form calca- 
 reous or siliceous shells. Although these shells are, with 
 few exceptions, exceedingly minute, the most part wholly 
 invisible unless highly magnified, they are in so vast num- 
 bers in many places, and multiply so rapidly, that they form 
 in time thick beds out of their accumulated shells. A square 
 yard covered with these microscopic species will increase 
 upward not only as fast as a square yard of an oyster-bank, 
 but much more rapidly, because of their extreme simplicity 
 of structure, their rapid reproduction, and the fact that 
 nearly the whole bulk of each one is in stony material. 
 
 The calcareous species, or Rhizopodz, abound in the shal- 
 lower waters along the borders of the ocean, and also over its 
 bottom where thousands of feet deep. Over what is called 
 the Telegraphic plateau, between Ireland and Newfoundland, 
 they appear to make a nearly continuous bed for a thousand 
 
266 DYNAMICAL GEOLOGY. 
 
 miles or more in breadth, and perhaps more than this from 
 north to south. The thickness of the great limestone- 
 formation there in progress, out of these minute shells, is 
 of course unknown. The genera of shallow water are 
 mostly different from those of the deep sea. 
 
 The siliceous species are either Diatoms or Polycystines. 
 They occur both in shallow and deep waters, like the Rhizo- 
 pods. The Diatoms are found in cold as well as warm seas, 
 and in fresh waters as well as marine. Over the bottoms of 
 shallow lakes they make thick beds, just as the Rhizopods 
 do in the ocean; and many of the peat-beds rest on a thick 
 layer of Diatoms made from species thaj; were living in the 
 lake that afterwards became the peat-growing swamp. 
 
 The rock made of Rhizopod shells is exemplified in chalk, 
 a soft white or whitish limestone. That consisting of 
 Diatoms often looks like a very fine whitish earth ; but it is 
 sometimes compacted into a nearly solid mass, and some- 
 times into an imperfect slate. 
 
 On p. 192 it is stated that the flint which occurs in chalk 
 may have been made from the silica of Diatoms and of the 
 spicula of sponges. 
 
 These are examples of beds formed by simple growth and 
 multiplication of living species. The shells are in size like 
 the grains of a fine powder; and it is only necessary that 
 they be consolidated as they lie, in order that a compact 
 rock shall be made out of the accumulation. 
 
 3. Coral-Reefs. 
 
 In tropical regions corals grow in vast plantations about 
 most oceanic islands and the shores of the continents. 
 The greatest depth at which the reef-making species live 
 is about 100 feet; and from this depth to sometimes a foot 
 above low-tide level, they flourish well. The patches or 
 groves of coral are usually distributed among larger areas 
 
CORAL-REEFS. 267 
 
 of coral sand, like small groves of trees or shrubbery in 
 some sandy plains. 
 
 The corals have much resemblance to vegetation in their 
 forms and their modes of growth; and the animals are 
 so like flowers in shape and bright colors that they are 
 called flower-animals (p. 57). Along with the corals there 
 are also great numbers of Shells, besides Crabs, Echini, and 
 other kinds of marine life. 
 
 The coral plantations are swept by the waves, and with 
 great force when the seas are driven by storms. The corals 
 are thus frequently broken, and the fragments washed about 
 until they are either worn to sand by the friction of piece 
 upon piece, or become buried in the holes among the growing 
 corals, or are washed up the beach. Corals are not injured 
 by mere breaking, any more than is vegetation by the clip- 
 ping of a branch, and those that are not torn up from the 
 very base and reduced to fragments continue to grow. 
 
 The fragments and sand made by the waves, and by the 
 eame means strewed over the bottom along with the shells 
 also of Mollusks, commence the formation of a bed of coral- 
 rock, literally a bed of limestone, for the coral and shells 
 have the composition of limestone. As the corals continue 
 growing over this bed, fragments and sand are constantly 
 forming, and the bed of limestone thus increases in thick- 
 ness. In this manner it goes on increasing until it reaches 
 the level of low tide ; beyond this it rises but little, because 
 corals cannot grow wholly out of water, and the waves have 
 too great force at this level to allow of their holding their 
 places, if they were able to stand the hot and drying sun. 
 The bed of calcareous rock thus produced is a coral-reef. 
 
 Since reef-corals grow to a depth of only 100 feet, the 
 thickness of the reef cannot much exceed 100 feet if the 
 sea-bottom remains at a constant level, except where there 
 are oceanic currents to transport to greater depths the sand 
 that is made. But should the reef-region be slowly sink- 
 
268 
 
 DYNAMICAL GEOLOGY. 
 
 ing at a rate not faster than the corals can grow and make 
 the reef rise, then almost any thickness may be made. From 
 observations about the coral regions of the Pacific, it is sup- 
 posed that some of the reefs have a thickness of two or 
 three thousand feet or more, which has been acquired during 
 such a slow subsidence. 
 
 The coral formations of the Pacific are sometimes broad 
 reefs around hilly or mountainous islands, as shown in the 
 annexed sketch. To the left in the sketch there is an inner 
 
 View of a high island, bordered by coral-reefs. 
 
 reef and an outer reef, separated by a channel of water, the 
 inner of which (/) is called a fringing reef, and the outer 
 (>) a barrier reef. They are united in one beneath the 
 water. At intervals there are usually openings through the 
 barrier reef, as at A, A, which are entrances to harbors. The 
 channels are sometimes deep enough for ships to pass from 
 harbor to harbor. 
 
 Many other coral-reefs stand alone in the ocean, far from 
 any other lands. The latter are called coral islands, or atolls. 
 
 Fig. 361. 
 
 Coral island, or Atoll. 
 
 They usually consist of a narrow reef encircling a salt- 
 water lake. The lake is but a patch of ocean enclosed by 
 
CORAL-REEFS. 269 
 
 the reef and its groves of palms and other tropical plants. 
 
 "When there are deep openings through the reef, ships 
 
 may enter the lake, or lagoon, as it is usually called, and 
 
 find excellent anchorage. The annexed F . 
 
 figure (fig. 362) is a map of one of the atolls 
 
 of the Kingsmill Islands in the Pacific. The 
 
 reef on one side the windward is wooded 
 
 throughout ; but on the other it has only a 
 
 few wooded islets, the rest being bare and 
 
 partly washed by the tides. At e there is 
 
 an opening to the lagoon. 
 
 The Paumotu archipelago, just northeast A P ia > of the Kin s smiu 
 of the Society Islands, contains between 70 
 and 80 coral islands ; the Carolines, with the Eadack, Ealick, 
 and Kingsmill groups on their eastern border, as many 
 more ; and others are scattered over the intervening ocean. 
 Most of the high islands between the parallels of 28 north 
 and south of the equator, and also the borders of the. con- 
 tinents, have their fringe of coral-reefs, unless (1) the waters 
 adjoining the coasts are too deep, or (2) the bottom is too- 
 muddy, or (3) the mouths of rivers are in the vicinity to 
 pour in fresh waters, which are injurious to corals, or (4) 
 cold oceanic currents sweep the coasts. Corals are limited 
 by the parallel of 28, because they will not flourish where 
 the mean temperature of the coldest winter month is below 
 68 F. 
 
 The limestone beds made from corals and shells are not 
 a result of growth alone, as in the case of the deposits 
 formed from microscopic organisms, but of growth in con- 
 nection with the breaking and wearing action of the ocean's waves 
 and currents. Corals and shells, unaided, could make only an 
 open mass full of large holes, and not a solid rock. There 
 must be sand or fine fragments at hand, such as the waters 
 can and do constantly make in such regions, in order to fill 
 up the spaces or interstices between the corals or shells. If 
 
270 DYNAMICAL GEOLOGY. 
 
 there is clayey or ordinary siliceous sand at hand, this will 
 suffice, but it will not make a pure limestone; in order to 
 have the rock a proper limestone, the shells and corals must 
 be the source of the sand or fine fragments, for these alone 
 yield the needed calcareous material and cement. The 
 limestone made in this way by the help of the waves 
 may be, and often is, as fine-grained as a piece of flint or 
 any ordinary limestone. In other cases it contains some 
 imbedded fragments in the solid bed; in others it is a coral 
 conglomerate; and over still other large areas it is a mass of 
 standing corals with the interstices filled in solid with the 
 sand and fragments. In some regions the compact coral 
 limestone is an oolite (p. 25). 
 
 The pages on the results of microscopic life have explained 
 one method by which the ancient limestones of the globe 
 have been made. The process of limestone-making now 
 going on through the agency of coral animals illustrates 
 another method, and far the most common. The beds, in 
 the case of these limestones, are a result of the slow growth 
 of living corals, crinoids, shells, and the like, and the gradual 
 wearing of the calcareous remains more or less completely 
 to sand and pebbles, preparatory for consolidation. 
 
 The extent of some of the modern reefs matches nearly that 
 of some of the Paleozoic reefs. On the north of the Feejee 
 Islands the reef-grounds are 5 to 15 miles in width. In New 
 Caledonia they extend 150 miles north of the island and 50 
 miles south, making a total length of 400 miles. Along 
 northeastern Australia they stretch on, although with many 
 interruptions, for 1000 miles. The modern reef-grounds, 
 although often of great length, are, however, narrow, unlike 
 those of the early geological ages. But this difference arises 
 from the fact that the regions giving the requisite depth for 
 abundant Coral and Molluscan life are now of narrow limits, 
 being confined to the borders of the continents, whereas in 
 ancient time the continents were to a large extent sub- 
 
THE ATMOSPHERE. 271 
 
 merged at shallow depths and afforded the conditions requi- 
 site for immense Coral, Crinoidal, and Molluscan planta- 
 tions. 
 
 II. THE ATMOSPHEKE. 
 
 The following are some of the mechanical effects con- 
 nected with the movements of the atmosphere. 
 
 1. Destructive effects from the transportation of sand, dust, etc. 
 The streets of most cities, as well as the roads of the 
 country, in a dry summer day, afford examples of the drift 
 of dust by the winds. The dust is borne most abundantly 
 in the direction of the prevalent winds, and may in the 
 course of time make deep beds. The dust that finds its way 
 through the windows into a neglected room indicates what 
 may be done in the progress of centuries where circum- 
 stances are more favorable. 
 
 The moving sands of a desert or seacoast are the more 
 important examples of this kind of action. 
 
 On seashores, where there is a sea-beach, the loose sands 
 composing it are driven inland by the winds into parallel 
 ridges higher than the beach, forming drift-sand hills. They 
 are grouped somewhat irregularly, owing to the course of 
 the wind among them, and also to little inequalities of com- 
 pactness or to protection from vegetation. They form 
 especially (1) where the sand is almost purely siliceous, 
 and therefore not at all adhesive even when wet, and not 
 good for giving root to grasses ; and (2) on windward coasts. 
 They are common on the windward side, and especially the 
 projecting points, even of a coral island, but never occur on 
 the leeward side, unless this side is the windward during 
 some portion of the year. On the north side of Oahu they 
 are thirty feet high and made of coral sand. Some of them, 
 which stand still higher (owing to an elevation of the 
 island), have been solidified, and they show, where cut 
 through, that they consist of thin layers lapping over one 
 
 . 24 
 
272 DYNAMICAL GEOLOGY. 
 
 another; and they evince also, by the abrupt changes of 
 direction in the layers (see fig. 17 /), that the growing hill 
 was often cut partly down or through by storms, and again 
 and again completed itself after such disasters. 
 
 This style of lamination and irregularity is characteristic 
 of the drift-sand hills of all coasts. On the southern shore 
 of Long Island there are series of sand-hills of the kind 
 described, extending along for one hundred miles, and five 
 to thirty feet high. They are partially anchored by strag- 
 gling tufts of grass. The coast of New Jersey down to the 
 Chesapeake is similarly fronted by sand-hills. In Norfolk, 
 England, between Hunstanton and Weybourne, the sand- 
 hills are fifty to sixty feet high. 
 
 2. Additions to land by means of drift-sands. The drift-sand 
 hills are a means of recovering lands from the sea. The 
 appearance of a bank at the water's surface off an estuary at 
 the mouth of a stream is followed by the formation of a 
 beach, and then the raising of hills of sand by the winds, 
 which enlarge till they sometimes close up the estuary, 
 exclude the tides, and thus aid in the recovery of the land 
 by the depositions of river-detritus. Lyell observes that 
 at Yarmouth, England, thousands of acres of cultivated 
 land have thus been gained from a former estuary. In all 
 such results the action of the waves in first forming the 
 beach is a very important part of the whole. 
 
 3. Destructive effects of drift-sands Dunes. Dunes are 
 regions of loose drift-sand near the sea. In Norfolk, Eng- 
 land, between Hunstanton and Weybourne, the drift-sands 
 have travelled inland with great destructive effects, burying 
 farms and houses. They reach, however, but a few miles 
 from the coast-line, and were it not that the sea-shore itself 
 is being undermined by the waves, and is thus moving 
 landward, the effects would soon reach their limit. 
 
 In the desert latitudes, drift-sands are more extended in 
 their effects. 
 
WATER. 273 
 
 4. Sand-scratches. The sands carried by the winds, when 
 passing over rocks, sometimes wear them smooth, or cover 
 the surface with scratches and furrows, as observed by Wm. 
 P. Blake over granite rocks at the Pass of San Bernardino 
 in California. Even quartz was polished, and garnets were 
 left projecting upon pedicels of feldspar. Limestone was 
 so much worn as to look as if the surface had been removed 
 by solution. Glass in the windows of houses on Cape Cod 
 sometimes has holes worn through it by the same means. 
 
 III. WATER 
 
 The subject of "Water is here considered under the follow- 
 ing heads : 
 
 1. FRESH WATERS; including especially Rivers and the 
 smaller Lakes, and also subterranean as well as superficial 
 w r aters. 
 
 2. The OCEAN ; including, along with the ocean, the larger 
 Lakes, whether salt or fresh. 
 
 3. FROZEN WATERS, or Glaciers and Icebergs. 
 
 1. FEESH WATEES. 
 A. SUPERFICIAL WATERS, OR RIVERS. 
 
 The mechanical effects of fresh waters are 
 
 1. Erosion, or wear. 
 
 2. Transportation of earth, gravel, stones, etc. 
 
 3. Distribution of the transported material, and formation 
 of fragmental deposits. 
 
 1. Erosion. 
 
 The waters of rivers descend in the form of rain and 
 snow from the clouds, and are derived by evaporation both 
 from the surface of the land, with its lakes, rivers, and 
 foliage, and from the ocean, but mostly from the latter. The 
 waters rise into the upper regions of the atmosphere, and, 
 
274 DYNAMICAL GEOLOGY. 
 
 becoming condensed into drops or snow-flakes, fall over the 
 hills and plains. They gather first into rills ; these, as they 
 descend, unite into rivulets; these, again, if the region is 
 elevated or mountainous, into torrents; torrents, flowing 
 down the different mountain valleys, combine with other 
 torrents to form rivers; and rivers from one mountain- 
 chain sometimes join the rivers from another and make a 
 common stream of great magnitude, like the Mississippi or 
 the Amazon. 
 
 The Mississippi has its tributaries among all the central 
 heights of the Great Eocky Mountain chain, throughout a 
 distance of 1000 miles, or between the parallels of 35 N. 
 and 50 N". ; and still another set of tributaries gather in 
 waters from the Appalachian chain, between western New 
 York and Alabama. Bills, rivulets, torrents, and rivers 
 combine over an area of millions of square miles to make 
 the great central trunk of the North American continent. 
 
 The amount of water poured each year into the ocean by 
 the Mississippi averages 19 trillions (19,500,000,000,000) 
 cfabic feet, varying from 11 trillions in dry years to 27 
 trillions in wet years. This amount is about one-quarter of 
 that furnished by the rains, the rest being lost mostly by 
 direct evaporation, but also in part by absorption into the 
 soil and by contributing to the growth of vegetation. 
 
 Erosion, or wear, goes on wherever the waters have 
 motion. The rain-drop makes an impression (fig. 21) 
 where it falls ; the rill and rivulet carry off light sand and 
 deepen their bed, as may be seen on any sand-bank or by 
 many a roadside; torrents work with far greater power, 
 tearing up rocks and trees as they plunge along, and, in the 
 course of time, making deep gorges or valleys in the moun- 
 tain-slopes ; and rivers, especially in periods of flood, hurry 
 on with vast power, making wider valleys over the breadth 
 of a continent. 
 
 The slopes of a lofty mountain, exposed through ages to 
 
WATER. 275 
 
 the" action described, finally become reduced to a series of 
 valleys and ridges, and the summit often to towering peaks 
 and crested heights, all these eifects originating in the fall 
 of rain-drops or snow-flakes. 
 
 The tendency of many rocks to decompose, aids th_e 
 waters in producing their mechanical eifects. 
 
 Where the stream has a rapid descent, and is therefore a 
 torrent, it plunges on with great violence and erodes mainly 
 along its bottom. Lower down the mountain, where the 
 slope of its bed is gentle, it becomes more quiet, and exca- 
 vates but slightly, if at all, at bottom. In its floods, how- 
 ever, it spreads beyond its banks and tears away the earth 
 or rocks, encroaching on the hills either side, and making 
 for itself a broad flat, or flood-plain. As the floods cease, 
 the stream Becomes again confined to its channel. Every 
 river has thus its channel for the dry season, and its flood- 
 plain which it covers in times of overflowing. 
 
 The great rivers of the continents, as well as the stream- 
 lets along roadsides, illustrate this subject. Wherever, in 
 countries that have rain, there is a ridge, be it small OF 
 large, there are gullies, or gorges, or valleys; and if any of 
 its streams are followed up to their head, there will be 
 found, first, the channel and its bordering flood-plain; then 
 the narrower valley with the hurrying torrent, receiving 
 smaller torrents along its course ; then, towards the top, the 
 torrent dwindling to a rivulet, or, if the summit is nearly 
 flat and wooded, there may be at top wet swampy land or 
 lakes. 
 
 A cascade usually occurs on a rapid stream, where in the 
 course of it there is a hard bed of rock overlying a soft one. 
 The hard bed resists wear, while the soft one below yields 
 easily : thus a plunge begins, which increases in force as it 
 increases in extent. The rills and rivulets made by a shower 
 of rain along roadsides or sand-banks often illustrate also 
 this feature of the great mountain streams. 
 
 24* 
 
276 
 
 DYNAMICAL GEOLOGY. 
 
 When the rocks underlying a region are nearly horizon- 
 tal, the valleys cut by the rivers have usually bold rocky sides. 
 In many parts of the Eocky Mountains the streams have 
 worked their way down through the rocks for hundreds, 
 and at times even thousands, of feet. Such a place is often 
 called a canon (pronounced as if spelled canyon). 
 
 These canons are of wonderful magnitude and depth on 
 the Colorado Kiver, over the west slope of the Eocky 
 Mountains, between longitude 111 W. and 115 W. For 
 
 Fig. 363. 
 
 CaSon of the Colorado near its junction with Green River. 
 
 300 miles there is a continuous canon, 3000 to 6000 feet 
 deep. The annexed sketch, furnished the author by Dr. 
 
WATER. 277 
 
 Newberry (the Geologist of the Expedition, under Lieuten- 
 ant J. C. Ives, that surveyed this region and first made 
 known the facts), represents the great plain of the Colorado 
 region, with its deep vertical cuts opening down to running 
 water. This water is the Colorado Eiver, and the opening 
 that looks so much like a mere crack in the rocks has a 
 depth at the place of about 3000 feet. The deep gorge is 
 the result, as stated by Dr. Newberry, of erosion by the 
 stream, which is still continuing its wearing action. The 
 isolated flat-topped hills and turreted rocks in the distance 
 are portions of strata that once covered the other rocks, 
 being all of the upper formations that the eroding waters 
 have left. 
 
 The rocky gorge, 7 miles long and 200 to 250 feet deep, 
 in which the Niagara River flows in violent rapids after its 
 plunge at the great fall, is believed with reason to have been 
 made by the waters, and mainly through the action of the 
 plunging stream at the fall. Every year rocks are under- 
 mined and tumbled down into the depths below, and thus 
 the position of the fall is slowly changing, moving higher 
 and higher up stream with the successive years. The rock, 
 for half the height of the fall, or 80 feet, is of hard lime- 
 stone ; but the lower half is of soft shale, and, being easily 
 worn away by the waters, it undermines the limestone and 
 thus assists in the movement. 
 
 2. Transportation by rivers, and distribution of transported 
 
 material. 
 
 1. Fact of transportation. It has been stated that the 
 massive mountains have been eroded into valleys and ridges 
 by running water. The material worn out has been trans- 
 ported somewhere by the same waters. 
 
 Part of the transported material in all such operations 
 goes to form the great alluvial plains that occupy the river- 
 valleys throughout their course. Part is carried on to the 
 
'4 
 
 278 DYNAMICAL GEOLOGY. 
 
 sea into which the river empties, when it meets the counter- 
 acting waves and currents and is distributed for the most 
 part along the shores, filling estuaries or bays, or making 
 deltas, and extending the bounds of the land. 
 
 Thus the mountains of a continent are ever on the move 
 seaward, and contribute to the enlargement of the seashore 
 plains. The continent is losing annually in mean height, 
 but gaining in width or extent of dry land. 
 
 2. The transporting power of water. The transporting 
 power of running water is very great when the flow is 
 rapid. Doubling the rate of flow increases sixty-four times 
 the force of the water. Large stones and masses of rocks 
 are torn up and moved^onward by the mountain-torrent; 
 pebbles, when the current runs but a few miles per hour; 
 and at slower rates, gravel, sand, or, when very slow, only 
 fine clay. Hence, as a stream loses in rapidity of movement, 
 it leaves behind the coarser material, and carries only the 
 finer ; if the rate becomes very slow, it drops the gravel or 
 the sand, and bears on only the finest earth or clay. 
 
 Consequently, where the current is swift, the bottom (and 
 the shores also wherever the current strikes them) is stony 
 or pebbly ; and where the water is still, or nearly so, the 
 bottom and shores are muddy. 
 
 The larger part of the transportation by rivers is done in 
 their seasons of flood. Then it is that streams are muddy 
 with the earth they are bearing along. 
 
 3. Wearing action on the transported material. The stones 
 are not only transported by the waters, but by the mutual 
 friction thus produced they are made into rounded stones 
 and reduced to pebbles and earth. Nearly all the rounded 
 stones, gravel, and earth of fields and gardens over the 
 globe, and also the material of all geological formations, has 
 been made out of pre-existing solid rocks by the wearing 
 action of waters, either those of streams over the land, or 
 those of the ocean. 
 
WATER. 279 
 
 The finer transported material is called detritus (from the 
 Latin for worn out), and also silt. The rounded stones are 
 termed boulders. 
 
 4. Amount of material transported. The amount of tran- 
 sported material varies with the size and current of the 
 rivers and the kind of country they flow through. The 
 Mississippi carries to the Gulf of Mexico, according to Hum- 
 phreys & Abbot, annually, on an average, 812,500,000,000 
 pounds of silt, equal to a mass one square mile in area and 
 241 feet deep, and its bottom-waters push on enough more 
 to make the 241 feet 268 feet. The total annual discharge 
 of silt by the Ganges has been estimated at 6.368,000,000 
 cubic feet. 
 
 5. Alluvial formations. The deposits made by the tran- 
 sported material which now constitute the alluvial plains of 
 the river-valleys cover a very large part of a continent, 
 since rivers or smaller streams are almost everywhere at 
 work. They are made up of layers of pebbles or gravel, 
 and of earth, silt, or clay, especially of these finer mate- 
 rials. Some logs, leaves, and bones occur in them ; but these 
 are rare ; for whatever floats down stream is widely scat- 
 tered by the waters, and to a great extent destroyed by 
 wear and decay. 
 
 6. Estuary and delta formations. The detritus-material 
 discharged by the river at its mouth tends to fill up the bay 
 into which it empties, and make wide flats on its borders, and 
 thus contract it to the breadth merely of the river-current. 
 
 Where the tides are feeble and the river large, the deposits 
 about the mouth of the stream gradually encroach on the 
 ocean, and make great plains and marshy flats, which are 
 intersected by the many mouths of the river and a network 
 of cross-channels. Such a formation is called a delta. 
 Figure 364 represents the delta of the Mississippi, the white 
 lines being the water-channels, and the black the great allu- 
 vial plains. The delta properly commences below the mouth 
 
 UNIVERSITY 
 
280 
 
 DYNAMICAL GEOLOGY. 
 
 of Eed River, where the Atchafalaya bayou, or side-channel 
 of the river, begins. The whole area is about 12,300 square 
 
 miles; about one-third is a sea-marsh, only two-thirds lying 
 above the level of the Gulf. 
 
 The deltas of the Nile, Ganges, and Amazon are similar 
 in general features to that of the Mississippi. 
 
WATER. 
 
 281 
 
 The detritus poured into the ocean where the tides or 
 ciirrents are strong, and a considerable part of that where 
 the tides are feeble, goes to form seashore flats and sand- 
 banks and off-shore deposits. In their formation the ocean 
 takes part through its waves and currents ; and hence they 
 are more conveniently described in connection with the 
 remarks on oceanic action. 
 
 B. SUBTERRANEAN WATERS. 
 
 1. Origin and course of subterranean waters. A part of the 
 waters that fall on the earth's surface on its mountains as 
 well as its plains sinks through the ground and often 
 penetrates to unknown depths between the strata or their 
 layers. Such under-ground waters become under-ground 
 streams ; and, as their channels are surrounded by rocks, the 
 water flows actually in a tube. When, therefore, they have 
 their source in elevated regions, the pressure increases with 
 the descent, and wherever an opening in the country below 
 gives them a chance of 
 escape, they often come out 
 with great force. By boring 
 down through the rocks, 
 such an under-ground 
 stream may be struck in 
 almost any region, and fre- 
 quently the water will rise 
 and rush out of the opening 
 
 in a jet Of great height. Section illustrating the origin of Artesian wells. 
 
 In fig. 365 the under-ground waters are supposed to enter at 
 , along a clayey layer (for clayey layers hold the water, 
 while it will soak through a sandy one) ; it escapes by the 
 boring b c, and is thrown up in a jet to d. There is so much 
 friction along the bed of the stream in the course of its 
 descent, that the height of the jet is always much less than 
 the whole descent, or b e. 
 
 Fig. 365. 
 
282 DYNAMICAL GEOLOGY. 
 
 Such wells are usually called Artesian wells or borings, from 
 the district of Artois in France, where they were early 
 made. The Artesian well of Grenelle in Paris is 2000 feet 
 deep. One at St. Louis has a depth of 2200 feet ; another 
 at Louisville is over 2000 feet. Such wells are used for 
 agricultural purposes in California, and for manufacturing 
 in various cities, as New York, New Haven, etc. 
 
 The under-ground waters often gush out along a seashore, 
 or from beneath the sea ; and sometimes in so great volume 
 that vessels at certain seasons are enabled to take in fresh 
 water from alongside while lying off in a harbor. 
 
 They flow and have cascades in many caverns, as in the 
 Mammoth Cave, Kentucky, the Adelberg Cave near Trieste 
 in Austria, and many others. In some cases they come out 
 to the surface in sufficient volume to turn a mill, and are set 
 to work immediately on their showing themselves. 
 
 2. Erosion. Subterranean waters have eroding and tran- 
 sporting power, as well as those of the land, and may exca- 
 vate large channels. 
 
 3. Land-slides. Land-slides are of different kinds : 
 
 (1.) The sliding of the surface earth or gravel of a hill 
 down to the plain below. This effect may be caused by the 
 waters of a severe storm wetting the material deeply and 
 giving it greatly increased weight, besides loosening its attach- 
 ment to the more solid mass below. 
 
 (2.) The sliding down a declivity to the plain below of 
 the upper layer of a rock-formation. This may happen 
 when this upper layer rests on a clayey or sandy layer and 
 the latter becomes very wet and greatly softened by the 
 waters ; the upper layer slides down on the softened bed. 
 
 (3.) The settling of the ground over a large area. This 
 may take place when a layer of clay or loose sand becomes 
 wet and softened by percolating waters, and then is pressed 
 out laterally by the weight of the superincumbent layers. 
 
WATER. 283 
 
 But this effect cannot be produced unless there happens to 
 be a chance for the wet layer to move or escape laterally. 
 
 2. THE OCEAN. 
 
 The ocean is vast in extent and vast in the power which 
 it may exert. But its mechanical work in Geology is mostly 
 confined to its coasts and to soundings, where alone material 
 exists in quantity within reach of the waves or currents. 
 In ancient time, when the continents were nearly flat and to 
 a great extent- submerged at shallow depths, this work was 
 performed simultaneously over a large part of their surface, 
 and strata nearly of continental extent were sometimes 
 formed. In the present age, oceanic action is confined to 
 the borders of the continents. 
 
 The mechanical effects of the ocean are produced by its 
 waves and currents. 
 
 1. Erosion and Transportation. 
 
 1. Waves, (1.) General action. The oceanic waves are a 
 constant force. Night and day, year in and year out, with 
 hardly an intermission, they break against the beaches and 
 rocks of the coasts; sometimes gently, sometimes in heavy 
 plunges that have the force of a Niagara of almost unlimited 
 breadth. The gentlest movements have some grinding 
 action on the sands, while the heaviest may dislodge and 
 move along up the shores rocks many tons in weight. 
 Niagara wastes its power by falling into an abyss of waters : 
 while in the case of the waves the rocks are bared anew for 
 each successive plunge. Cliffs are undermined, rocks are worn 
 to pebbles and sand, and sand ground to the finest powder. 
 Rocky headlands on windward coasts are especially exposed 
 to wear, since they are open to the battering force from 
 different directions. 
 
 (2.) Level of greatest eroding action. The eroding action 
 
 25 
 
284 DYNAMICAL GEOLOGY. 
 
 is greatest for a short distance above the height of half-tide, 
 and, except in violent storms, it is almost null helow low-tide 
 
 level. Figure 366 represents 
 
 i TIC -u Fig- 366 - 
 
 in profile a cliff, having its c r'~ 
 
 lower layers, near the level of Ell- ~~I~ 
 
 low-tide, extending out as a 
 platform a hundred yards wide. 
 As the tide commences to move 
 in, the waters while still quiet 
 
 swell over and cover this platform, and so give it their pro- 
 tection ; and the force of wave-action, which is greatest 
 above half-tide, is mainly expended near the base of the 
 cliff, just above the level of the platform. 
 
 (3.) Action landward. Waves on shallow soundings have 
 some transporting power; and, as they always move toward 
 the land, their action is landward. They thus beat back, 
 little by little, any detritus in the waters, preventing that 
 loss to continents or islands which would take place if it 
 were carried out to sea. 
 
 (4.) Effect on outline of coasts No excavation of narrow 
 valleys. As the action of waves on a coast tends to wear 
 away headlands, and at the same time to fill up bays with 
 detritus, the general result will be to render the outline 
 more regular or even. There is nowhere a tendency to 
 excavate narrow valleys into a coast, like those occupied by 
 rivers. Such valleys are made by the waters of the land ; 
 for the ocean can work at valley-making only when it has 
 already an open channel for the waters to pass through, 
 and then the valleys are of very great width. If a continent 
 were sinking slowly in the ocean, or rising slowly from it, 
 wave-action would still be attended by the same results; for 
 each part of the surface would be successively a coast-line, 
 and over each there would be the same wearing away of 
 headlands and filling of bays, instead of the excavation of 
 valleys. 
 
WATER. 285 
 
 2. Tidal currents. Tidal currents often have great strength 
 when the tide moves through channels or among islands, 
 and consequently are a means of erosion and transportation 
 in daily action wherever there is mud or sand within their 
 reach, as is usually the case in the vicinity of the land.* 
 
 The out-flowing current, or that connected with the ebbing 
 tide, is deeper in its action and has, therefore, more excavating 
 and more transporting power than the in-flowing, or that of 
 the incoming tide. The latter moves on as a great swelling 
 wave, and fills the bays much above their natural level ; but 
 the out-flowing current begins along the bottom in bays 
 before the tide is wholly in, owing to the accumulation of 
 waters, and when the tide changes it adds to the strong 
 current-movement already in progress. 
 
 The piling up of the waters in a bay by the tides, or by 
 storms, produces, especially if the entrance is not very 
 broad, a strong out-flowing current at bottom, which tends 
 to keep the channel deep and clear of obstructions. 
 
 The bore or eagre of some great rivers is a kind of tidal 
 flow up a stream. It is produced when the regular rise of 
 the tide in the bay at the mouth of the river is prevented 
 by the form of the entrance and its sand-banks, together 
 with the outflow of the river, so that the waters are for a 
 while prevented from entering until, finally, all of one tide 
 rush in at once, or in a few great waves. The eagres of 
 the Amazon, the Hoogly in India (one of the mouths of the 
 Ganges), and the Tsien-tang in China, are among the most 
 remarkable. In the case of the Tsien-tang, the water moves 
 up stream in one great wave, plunging like an advancing 
 cataract, 4 or 5 miles broad and 30 feet high, at a rate of 25 
 miles an hour. The boats in the middle Qf the stream 
 simply rise and fall with the passage of the wave, being 
 pushed forward only a short distance ; but along the shores 
 there is great devastation, the banks being worn away and 
 animals often surprised and destroyed. 
 
286 DYNAMICAL GEOLOGY. 
 
 3. Currents made by winds. There are also currents pro- 
 duced by winds, especially when there are long storms, or 
 when the winds blow for months in one direction. The 
 currents thus made have but little depth. Sweeping by an 
 island, they transport from one place to another in their 
 course -more or less of the sand of the shores, and the same 
 sand may be in part carried back again when the season 
 changes to that in which the wind blows from the opposite 
 direction. Other portions of detritus may be carried by 
 them away from the island and distributed in the deeper 
 waters. 
 
 4. Great oceanic currents. The great currents of the ocean, 
 like that called the Gulf Stream, are for the most part so 
 distant from the borders of the continents that little detritus 
 comes w T ithin their reach. As these currents have great 
 depth, often a thousand feet or more, their course is deter- 
 mined by the deep-water slopes of the submerged border of 
 a continent, so that when the submerged border is shallow 
 for a long distance out (as off New Jersey and Virginia, 
 where this long distance is even 50 to 80 miles), the current 
 is equally remote, and exerts very feeble if any action near 
 the shores. Wherever it actually sweeps close along a 
 coast, it will bear away some detritus to drop it over the 
 bottom in the neighboring waters. 
 
 The oceanic currents flowing from polar seas produce 
 important effects by means of the icebergs which they bear 
 into warmer latitudes. These icebergs are freighted with 
 thousands of tons of earth and stones; and wherever they 
 melt, they drop the whole to the ocean's bottom. The sea 
 about the Newfoundland banks is one of the regions of 
 the melting bergs ; and there is no doubt that vast submarine 
 unstratified accumulations of such material have been there 
 made by this means. It has been suggested that the banks 
 may have been thus formed. 
 
WATER. 287 
 
 2. Distribution of material, and the formation of marine and 
 fluvio-marine deposits. 
 
 1. Origin of material. The material used by the waves 
 and currents is either (1) the stones, gravel, sand, or earth 
 produced by the wear of coasts ; or (2) the detritus brought 
 down by rivers and poured into the ocean, as explained on 
 page 281. 
 
 The latter in the present age is vastly the most important. 
 But in the earlier geological ages, when the dry land was 
 of very small extent, rivers were small and were but a feeble 
 agency. The ocean had then vastly greater advantages 
 than now, because, as stated on page 84, the continents 
 were mostly submerged at very shallow depths, or lay near 
 tide-level within reach of the waves and currents. 
 
 2. Forces in action. In the distribution of this material, 
 the waves and marine currents may work alone, in the man- 
 ner explained on the preceding pages, or in conjunction 
 with river-currents wherever these exist. 
 
 3. Marine formations. The marine formations are of the 
 following kinds : 
 
 (1.) Beach-accumulations. Beaches are made of the mate- 
 rial borne up the shores by the waves and tides and left above 
 tide-level. This material consists of stones or pebbles, sand, 
 mud, earth, or clay. It is coarse when the waves break 
 heavily, because, although trituration to powder is going on 
 at all times, the powerful wave-action and the undercurrent 
 carry off the finer material into the off-shore shallow 
 waters, where it settles over the bottom or is distributed by 
 currents. It is fine where the waves are gentle in movement, 
 as in sheltered bays, the triturated material remaining in 
 such places near where it is made, and often being the finest 
 of mud. 
 
 (2.) Sand-banks, or reefs Shallow-water accumulations. 
 Shallow-water accumulations may be produced in bays, 
 
288 DYNAMICAL GEOLOGY. 
 
 estuaries, or the inner channels of a coast, and over the 
 bottom outside. They consist usually of coarse or fine sand 
 and earthy detritus, but may include pebbles or stones when 
 the currents are strong. The material constituting them is 
 derived from the land through the triturating and tran- 
 sporting action of the waves and currents. The accumula- 
 tions may increase under wave-action in shallow water, 
 until they approach or rise above low-tide level, and then 
 they form sand-banks. Such sand-banks keep their place 
 in the face of the waves, for the same reason as the platform 
 of rock mentioned on page 284 and illustrated in fig. 366. 
 
 (3.) Fluvio-marine formations. Most of the accumula- 
 tions in progress on existing shores, whether sand-banks, or 
 estuary or off-shore deposits, especially about well-watered 
 continents, contain more or less of river-detritus, and are 
 modified in their forms by the action of river-currents. 
 Along the whole eastern coast of the United States south 
 of New England, and on all the borders of the Gulf of 
 Mexico, the formations in progress are mainly fluvio-marine, 
 that is, the combined result of rivers and the ocean. The 
 coast-region on the continent is now slowly widening 
 through this means, and has been widening for an indefinite 
 period. This coast-region is low, flat, often marshy, full of 
 channels or sounds; and facing the ocean there is a barrier 
 reef, made of sand. 
 
 The rivers pour out their detritus especially during their 
 floods, and the ocean's waves and currents meet it as the 
 tide sets in with a counter-action, or one from the seaward; 
 and between the two the waters lose in rate of flow and 
 drop the detritus over the bottom. When the river is very 
 large and the tides feeble, the banks and reefs extend far 
 out to sea. The Mississippi thus stretches its many-branched 
 mouth (p. 280) many miles into the Gulf. When the tide 
 is high, sand-bars are formed; and the higher the tides the 
 closer are the sand-bars to the coast. When the stream is 
 
WATER. 289 
 
 small, the ocean may throw a sand-bank quite across its 
 -mouth, so that there shall be no egress to the river-waters 
 except by percolation through the sand; or, if a channel be 
 left open, it may be only a shallow one. 
 
 3. Structure of the formations. 
 
 Beach-formations are very irregular in stratification. The 
 layers as shown in figure 17e, page 31 have but little 
 lateral extent, and change in character every few feet. 
 They often include patches of stones, as well as pebbles and 
 sand. 
 
 The sand-banks and reefs made along a coast have much 
 more regular stratification, and are mostly composed of sand 
 with some beds of pebbles. They often vary much every 
 mile or every few miles. 
 
 Those beds that are formed in shallow waters, as in bays 
 or in the off-shore waters, retain a uniformity of stratifica- 
 tion over much larger areas, and may consist of pebbles, 
 sand, or finer earth. The extent and regularity of level of 
 the submerged area will determine in a great degree the 
 extent to which the uniformity of stratification may extend ; 
 and in this respect the former geological ages, as observed 
 on page 287, had greatly the advantage of the present. 
 
 Hippie-marks (figure 18, p. 32) are made by the spread of 
 the waters in a wave up a beach, or by wave-action on the 
 bottom within soundings where the depth does not exceed 
 60 or 80 fathoms. Hill-marks (fig. 19) are produced when 
 the return waters of a tide, or of a wave that has broken 
 on a beach, flow by an obstacle, as a shell or pebble, and are 
 piled up a little by it so as to be made to plunge over it and 
 so erode the sands for a short distance below the obstacle. 
 The oblique lamination in a layer, or ebb-and-flow structure, 
 results from the rapid inward movement of the tide, or of a 
 current, over a sandy bottom : it makes a series of inclined 
 layers by the piling action; when the movement ceases, the 
 
290 DYNAMICAL GEOLOGY. 
 
 detritus will deposit horizontally for a while ; and afterward 
 the same inward movement may be repeated, producing 
 anew the oblique lamination. 
 
 The imbedded shells and other animal relics in a beach 
 are worn or broken ; those in the bays or off-shore shallow 
 waters out of the reach of the waves may be unbroken, or 
 may lie as they did when living; but if the waters are not 
 so deep but that the shells or corals are exposed to wave- 
 action, they may be broken or worn to powder, and enter in 
 this state into the formation in progress. See (page 85) the 
 remarks on the formation of limestone from shells or corals. 
 In the sands of beaches near low-tide level, borings of Sea- 
 worms, or of some Mollusks or Crustaceans, may exist. 
 
 3. FEBBznra AND FEOZEN WATEES. 
 
 
 
 A. FREEZING WATER. 
 
 As water in the act of freezing expands, the. freezing pro- 
 cess, when taking place in the seams of rock, opens the 
 seams and tears masses asunder. This kind of action is 
 especially destructive in the case of rocks that are much 
 fissured, or intersected by joints, or that have a slaty or 
 laminated structure. As the action continues through suc- 
 cessive years and centuries, it may result in great accumu- 
 lations of broken stone. The slope, or talus, of fragments 
 at the foot of bluffs of trap or basalt is often half as high as 
 the bluff itself. In tropical countries, bluffs have no such 
 masses of ruins at their base. 
 
 Granular rocks, whether crystalline or not, when they 
 readily absorb water, lose their surface-grains by the same 
 freezing process. Granite, as well as porous sandstones, 
 may thus be imperceptibly turning to dust, earth, or gravel. 
 In Alpine regions this action may be incessant. 
 
GLACIERS. 29] 
 
 B. FROZEN WATER. 
 
 The effects of ice and snow are conveniently considered 
 under three heads: 1. The ice of lakes and rivers; 2. 
 Glaciers; 3. Icebergs. 
 
 1. ICE OF LAKES AND RIVERS. 
 
 The ice of lakes and rivers often freezes about stones along 
 their shores, making them part of the mass; and other stones 
 sometimes fall on the surface from overhanging bluffs. In 
 times of high-water, or floods, the ice, rising with the 
 waters, may carry its burden high up the shores, or over 
 the flooded flats, to leave them there as it melts ; or, if 
 within reach of the current, it may transport the stones far 
 down stream. This is a common method of transportation 
 by ice. Large accumulations of boulders are sometimes 
 made by this means on the shores of lakes far above the 
 ordinary level of the waters. 
 
 2. GLACIERS. 
 
 1. Glaciers are ice-streams, or rivers in which the moving 
 material is frozen instead of liquid water. 
 
 Like large rivers, they have their sources in high moun- 
 tains, derive their waters from the clouds, and descend along 
 the valleys; but the mountains are such as take snow from 
 the clouds instead of rain, because of their elevation. They 
 rise only in those mountains that receive annually a large 
 supply of snow from the clouds ; for the snow must accumu- 
 late to a great depth. 
 
 Like large rivers, many tributary streams coming from 
 the different valleys unite to make the great stream. 
 
 As with rivers, their movement is owing to gravity, or to 
 the weight of the material ; but the average rate of motion, 
 instead of being some miles an hour, is generally but 8 to 
 10 inches a day, or a mile in 15 to 25 years. 
 
292 DYNAMICAL GEOLOGY. 
 
 As with rivers, the central portions move most rapidly, 
 the sides and bottom being retarded by friction; but the 
 difference of rate between the sides and bottom is far 
 greater in glaciers than in rivers. 
 
 The snow of the mountain-tops, which is perhaps hun- 
 dreds of feet deep, becomes compacted and converted into 
 ice mainly by its own weight; and thus the glacier begins. 
 As it starts on its course, the clouds furnish new snows to 
 keep up the supply and help press on the moving mass. 
 
 2. Fractures attending the movement Crevasses. Every val- 
 ley has its ridgy sides, its sharp turns, its abrupt narrowings 
 and widenings, its irregular bottom ; and the stiff ice, com- 
 pelled to accommodate itself to these irregularities, has, 
 consequently, profound crevasses made usually along its 
 borders, besides multitudes of cracks that are not visible at 
 the surface ; also, still profounder chasms when wrenched 
 in turning some point; longer crevasses, crossing even its 
 whole breadth, when the ice plunges down a steep place 
 in an ice-cascade, or when, on escaping from a narrow 
 gorge, it moves off freely again with increase of slope. 
 Again, it may lose all its crevasses, from their closing up, 
 when the motion is impeded by diminished slope or other- 
 wise. 
 
 3. Descent below the snow-line. The icy mass thus descends 
 5000 to 7500 feet below the snow-line, or the limit of per- 
 petual snow. It resists the melting heat of summer because 
 of its mass, just like the ice in an ice-house. Though start- 
 ing where all is white and barren, it passes by regions of 
 Alpine flowers, and often continues down to a country of 
 gardens and human dwellings before its course is finally cut 
 short by the climate. Thus, the Her de Glace, which, under 
 the name of the Bois Glacier, rises in Mont Blanc and other 
 neighboring peaks, terminates in the vale of Chamouni. 
 And in a similar manner two great glaciers descend from 
 the Jungfrau and other heights of the Bernese Alps to 
 
GLACIERS. 
 
 293 
 
 the plains of the Grindelwald valley just south of Inter, 
 lachen. 
 
 Fig. 867 represents one of the ice-streams of the Mount 
 Rosa region in the Alps, from a view in Professor Agassiz's 
 work on Glaciers. It shows the lofty regions of perpetual 
 
 Fig. 367. 
 
 Glacier of Zermatt, or the Gorner Glacier. 
 
 snow in the distance ; the bare rocky slopes that border it, 
 later on its course ; and the many crevasses that intersect 
 the surface of the ice-stream. 
 
 4. Glacier torrent, The melting over the surface of a 
 glacier and about the sides of its crevasses gives origin to a 
 stream of water flowing beneath it, which becomes gradu- 
 ally a torrent of considerable size, and finally emerges to 
 the light from beneath the bluff of ice in which the glacier 
 
294 DYNAMICAL GEOLOGY. 
 
 terminates. Thence it continues on its rocky course down 
 the valley. 
 
 5. Method of movement. The movement and condition of 
 a glacier is almost wholly dependent on the facility with 
 which ice breaks and unites again into solid ice when the 
 broken surfaces are brought into contact. This quality, first 
 noticed by Faraday and applied to Glaciers by Tyndall, is 
 called regelation, the word meaning a freezing together again. 
 It is easily tried by breaking a lump of ice and bringing the 
 surfaces again into contact : if moist, as they are at the 
 ordinary temperature, they at once become firmly united. 
 A glacier moves on and accommodates itself to its uneven 
 bed by breaking when necessary, and in its progress it may 
 soon become as solid as before. Thus it breaks and mends 
 itself as it goes. 
 
 Small portions of a glacier may slide along its bed, but 
 the glacier never slides as a whole. In some places there 
 may be an adaptation to an uneven surface by bending 
 without breaking (which may take place if the force be ex- 
 ceedingly slow in action) ; but this also is a means of motion 
 of small importance, compared with the first mentioned. 
 
 6. Transportation by Glaciers Moraines. Glaciers become 
 laden with stones and earth falling from the heights above, 
 or coming down in crushing avalanches of snow and stones. 
 The stones and earth make a band along either border of a 
 glacier, and such a band is called a moraine. When two 
 glaciers unite, or a tributary glacier joins another, they 
 carry forward their bands of stones with them ; but those 
 on the uniting sides combine to make one moraine. A large 
 glacier like that in fig. 367 may have many moraines, or 
 one less than the number of its tributaries. Some of the 
 masses of rock on glaciers are of immense size. One is 
 mentioned containing over 200,000 cubic feet, which is 
 equivalent in cubic contents to a building 100 feet long, 50 
 wide, and 40 high. 
 
GLACIERS. 295 
 
 In the lower part of a glacier the several moraines lose 
 their distinctness through the melting of the ice; for this 
 brings to one level the dirt and stones of a considerable part 
 of its former thickness, and the surface, therefore, becomes 
 covered throughout with earth and stones. The bluff of ice 
 which forms the foot of a glacier is often a dirty mass, 
 showing little of its real nature in the distant view. 
 
 The final melting leaves all the earth and stones in 
 unstratified heaps or deposits, to be further transported, 
 eroded and arranged by the stream that flows from the 
 glacier. 
 
 7. Erosion by Glaciers. A glacier so laden with stones 
 must have stones in its lower surface and sides as well as 
 in its mass. As it moves down its valley, it consequently 
 abrades the exposed rocks over which it passes, smoothing 
 and polishing some surfaces, covering others closely with 
 parallel scratches, and often ploughing out broad and deep 
 channels, besides scratching or smoothing^ the ploughing 
 boulders. 
 
 In addition to these minor operations, glaciers deepen and 
 widen the valleys in which they move. In this work they 
 are aided by the frosts (p. 290), avalanches, and glacier 
 torrents. 
 
 8. Glacier regions. The best known of Glacier regions are 
 those of the Alps, in one of which Mont Blanc stands, with 
 its summit 15,760 feet above the sea. There are glaciers also 
 in the Pyrenees and the mountains of Norway, Spitzbergen, 
 in the Caucasus and Himalaya, in the Southern Andes, in 
 Greenland and other Arctic regions, etc. One of the Spitz- 
 bergen glaciers borders the coast for 11 miles with cliifs of 
 ice 100 to 400 feet high. The great Ilumboldt Glacier of 
 Greenland, north of 79 20', has a breadth at foot where it 
 enters the sea of 45 miles; and this is but one glacier among 
 many in that icy land. 
 
 26 
 
296 DYNAMICAL GEOLOGY. 
 
 3. ICEBERGS. 
 
 When a glacier like those of Greenland terminates in the 
 sea, the icy foot bearing its moraines becomes broken off 
 from time to time ; and these fragments of glaciers, floated 
 away by the sea, are icebergs. The geological effects of ice- 
 bergs have been stated on page 286. 
 
 4. FOKMATION OF SEDIMENTABY BEDS. 
 
 The following is a brief recapitulation of the explanations 
 of the origin of deposits given in the preceding pages. 
 Igneous and other crystalline rocks are not here included. 
 
 1. Sources of material, The material of sedimentary 
 rocks has come either (1) from the degradation of pre- 
 existing rocks, or (2) from a state of solution in the waters 
 of the globe. These waters have in general taken up their 
 mineral material originally from the rocks, except that part 
 which has always existed in the ocean ever since the ocean 
 began to be. 
 
 The principal means of degradation are the following : 
 1. Erosion by moving waters, either those of the sea or 
 land (pp. 283, 273) ; 2. Erosion by ice, either that of glaciers, 
 icebergs, or ordinary snow and ice (pp. 291, 295) ; 3. Pressure 
 of water filtrating into fissures ; 4. Freezing of water in 
 fissures (p. 290) ; 5. Chemical decomposition, in the course 
 of which rocks are crumbled down to fragments or earth. 
 
 2. Formation of deposits. The methods by which deposits 
 have been formed are the following : 
 
 1. By the waters of the sea. 
 
 (1.) Through the sweep of the ocean over the continents 
 when barely or partly submerged, making (a) sandy or pebbly 
 deposits near or at the surface where the waves strike, or 
 at very shallow depths where swept by a strong current ; 
 (6) argillaceous or shaly deposits near or at the surface, 
 
FORMATION OP SEDIMENTARY BEDS. 297 
 
 where sheltered from the waves, and also, at considerable 
 depths, out of material washed off the land by the waves or 
 currents ; but not making (c) coarse sandy or pebbly deposits 
 over the deep bed of the ocean, as even great rivers carry 
 only silt to the sea; and not making (d) argillaceous deposits 
 over the ocean's bed except along the borders of the land, 
 unless by the aid of a river like the Amazon, in which case, 
 still, the detritus is mostly thrown back on the coast by the 
 waves and currents. 
 
 (2.) Through the waves and currents of the ocean acting 
 on the borders of the continent with the same results as above, 
 except that the beds have less extent. 
 
 (3.) Through living species, and mainly Mollusks, Radiates, 
 and Rhizopods, affording calcareous material for strata (p. 
 19), and Diatoms and some Protozoans, siliceous material 
 (p. 14). All rocks made of corals, and the shells of Mol- 
 lusks, excepting the smallest, require the help of the waves 
 at least to fill up the interstices ; but Rhizopods and siliceous 
 Infusoria may make rocks in deep water, by accumulation, 
 which are in no sense sedimentary. See pp. 265, 266. 
 
 2. By the waters of lakes. Lacustrine deposits are essen- 
 tially like those of the ocean in mode of origin, unless the 
 lakes are small, when they are like those of rivers. 
 
 3. By the running waters of the land. (1.) Filling the val- 
 leys with alluvium, and moving the earth from the hills 
 over the plains (p. 277). (2.) Carrying detritus to the sea 
 or to lakes, to make, in conjunction with the action of the 
 sea or lake waters, delta and other seashore accumulations 
 (p. 279). 
 
 4. By frozen waters. (1.) Spreading the rocks and earth 
 of the higher lands over the lower, and, in the process, 
 bearing onward blocks of great size, such as cannot be moved 
 by other means, as well as finer material (pp. 291, 294). (2.) 
 Carrying rocks and earth from the land to the ocean, either 
 to the seashore, making accumulations in lines or moraines, 
 
298 DYNAMICAL GEOLOGY. 
 
 or to distant parts of the ocean, as from the Arctic to the 
 Newfoundland Banks; and thus contributing to deep or 
 shallow water or shore sedimentary accumulations, distin- 
 guished for the irregular intermingling of huge blocks of 
 stone, pebbles, and earth (p. 286). 
 
 5. GENEEAL EFFECTS OF EEOSION OYEE CON- 
 TINENTS. 
 
 The outlining of mountain-ridges and valleys has been in 
 part produced by subterranean forces upturning and frac- 
 turing the strata; but the final shaping of the heights is 
 due to erosion. This cause has been in action from the ear- 
 liest time, and the material of nearly all rocks not calcareous 
 have resulted from the erosion of pre-existing formations. 
 
 The Appalachians have probably lost by denudation 
 more material than they now contain. Mention has 
 been made of faults of even twenty thousand feet along 
 the course of the chain from Canada to Alabama. In 
 such a fault, one side is left standing twenty thousand 
 feet above the other, equivalent in height to some of the 
 loftier mountains of the globe ; and yet now the whole is so 
 levelled off that there is no evidence of the fault in the 
 surface-features of the country. The whole Appalachian 
 region consists of ridges of strata isolated by long distances 
 from others with which they were once continuous. Fig. 
 253 represents a common case of this kind. It is supposed 
 by some geologists that the Appalachian and Western coal- 
 fields were once united, and that, in western Ohio and other 
 parts of the intermediate region, strata thousands of feet 
 deep, from the Lower Silurian upward, have been removed, 
 and this over a surface many scores of thousands of square 
 miles in area. This view has been questioned on a former 
 page. Whether true or not, there is no doubt that the 
 anthracite coal-fields of central Pennsylvania were once a 
 part of the great bituminous coal-field of western Pennsyl- 
 
HEAT. 299 
 
 vania and Virginia (fig. 219, p. 118). They are now in iso- 
 lated patches, and formations of great extent have been 
 removed over the intervening country. The Illinois coal- 
 region is broken into many parts in consequence of similar 
 denudation and uplifts. 
 
 In New England there is evidence of erosion on a scale 
 of vast magnitude since the crystallization of its rocks. On 
 the summit-level between the head-waters of the Merrimac 
 and Connecticut, there are several pot-holes in hard granite; 
 one, as described by Professor Hubbard, is ten feet deep and 
 eight feet in diameter, and another is twelve feet deep. They 
 indicate the flow of a torrent for a long age where now it 
 is impossible; and the period may not be earlier than the 
 Post-tertiary. Many other similar cases are described by 
 Hitchcock. 
 
 These examples of denudation are sufficient for illustra- 
 tion. Europe and the other continents furnish others no 
 less remarkable, and to an indefinite extent. 
 
 IY. HEAT. 
 
 The crust of the earth derives heat from three sources : 
 1. The sun, an external source ; 2. The earth's heated inte- 
 rior; 3. Chemical and mechanical action. The first two 
 sources are geologically the most important. 
 
 Internal heat. The fact of a high heat in the earth's inte- 
 rior is established in various ways. 
 
 1. The form of the earth. The form of the earth is a 
 spheroid, and a spheroid of just the shape that would have 
 resulted from the earth's revolution on its axis, provided it 
 had passed through a state of complete fusion, or of igneous 
 fluidity, and had slowly cooled over its exterior. Hence 
 follows the conclusion that it has passed through such a 
 state of fusion, which is greatly strengthened by the other 
 evidence here given. Another conclusion also follow^: 
 namely, that the earth's axis had the same position (or, at 
 
 26* 
 
300 DYNAMICAL GEOLOGY. 
 
 least, very nearly the same) when cooling began as now. 
 There is no evidence that there has been at any time a 
 change. 
 
 2. Crystalline character of the lowest rocks. On descending 
 through the earth's strata, the lowest reached are crystalline 
 rocks. The Azoic rocks, which are the earliest, have been 
 found to be, wherever observed, either crystalline or firmly 
 consolidated, which proves that they must have been sub- 
 jected for a long time to the action of heat. 
 
 3. Artesian borings. In deep borings for water, like those 
 mentioned on page 282, it has been found that the tempera- 
 ture of the earth's crust increases one degree of Fahrenheit 
 for every 50 or 60 feet of descent. The rate of 1 F. for 50 
 feet of descent, in the latitude of New York, would give 
 heat enough to boil water at a depth of 8100 feet; and at a 
 depth of about 28 miles the temperature would be 3000 F., 
 or that of the fusing point of iron. Since, however, the 
 fusing temperature of any substance increases with the 
 pressure, the depth required before a material like iron 
 would be found in a melted state, would be greater than 
 this. The facts suffice at least to prove that the earth has 
 a source of heat within, and that a very high heat exists at 
 no great depth. If the solid crust is 100 miles thick, it is 
 still thin compared with the distance to the earth's centre. 
 
 4. Distribution of Volcanoes. The great Pacific Ocean has 
 nearly a complete girt of volcanoes, extinct or active, and 
 all of its many islands that are not coral are wholly volcanic 
 islands, excepting New Zealand and a few others of large 
 size in its southwest corner. Volcanoes occur along many 
 parts of the Andes from Tierra del Fuego to the Straits of 
 Darien, in Central America,- in Mexico, California, Oregon, 
 and beyond; in the Aleutian Islands on the north; in Kamt- 
 chatka, Japan, the Philippines, New Guinea, New Hebrides, 
 New Zealand on the west; and on Antarctic lands both 
 south of New Zealand and South America. The volcanic 
 
HEAT VOLCANOES. 301 
 
 region thus bounded is equal to a whole hemisphere, and is 
 ample proof as to the nature of the whole globe. With 
 outlets of fire so extensively distributed over this vast area, 
 there surely must be some universal seat of fire beneath. 
 
 But there are volcanoes also in the East Indies in great 
 numbers, both extinct and active, in the islands of the Indian 
 Ocean, in the West Indies, in the islands of the Atlantic, 
 and in the vicinity of the Mediterranean and Red Seas. 
 
 The various evidences mentioned combine to prove that 
 the interior of the earth is a source of heat. 
 
 EFFECTS OF HEAT. 
 
 The following are the effects of heat here considered : 
 
 1. Volcanoes. 
 
 2. Igneous ejections that are not volcanic. 
 
 3. Metamorphism, and the production of mineral veins. 
 
 The heat of the globe is also one of the causes of earth- 
 quakes, of change of level in the earth's crust, and of the 
 elevation of mountains : these subjects are considered in 
 the following chapter. It is an important agent also in all 
 chemical changes. 
 
 1. VOLCANOES. 
 
 A. General nature of volcanoes and their products. 
 Yolcanoes are mountain-elevations of a somewhat conical 
 form, which eject or have ejected at some time streams of 
 melted rock. If the fire-mountain has at present no active 
 fires within, and is emitting no vapors, it is said to be 
 extinct. The following figure is a sketch of the lofty volcano 
 of Cotopaxi, as published by Humboldt. The height of the 
 peak is 18,876 feet. The larger volcanic mountains are 
 seldom so steep as in this figure. Etna, about 10,000 feet 
 high, and Mount Kea and Mount Loa of Hawaii, nearly 
 14,000 feet, have an average slope of less than 10 degrees. 
 The form of a cone with a slope of 7 degrees which is the 
 
302 
 
 DYNAMICAL GEOLOGY. 
 
 average for the Hawaian volcanoes is shown in figs. 369, 
 370; fig. 369 has a pointed top, like Mount Kea, and fig. 370 
 
 Fi 
 
 Volcano of Cotopaxi. 
 
 a rounded outline, like Mount Loa, whose form is that of a 
 very low dome 
 
 Fig. 369. 
 
 Fig. 370. 
 
 The highest of volcanic mountains on the globe are the 
 Aconcagua peak in Chili, 23,000 feet, and Sorata and Illi- 
 mani, in Bolivia, each over 24,000 feet. The former appears 
 to be still emitting vapors, showing that the fires are not 
 wholly extinct. The mountains Shasta, Hood', 'Helens, and 
 
HEAT VOLCANOES. 303 
 
 others in California and Oregon are isolated volcanic cones 
 13,000 to 15,000 feet high. 
 
 The cavity or pit in the top of a volcanic mountain, 
 where the lavas may often be seen in fusion, is called the 
 crater. It is sometimes thousands of feet deep, but may be 
 quite shallow; and in extinct volcanoes it is often wholly 
 wanting, owing to its having been left filled when the fires 
 went out. 
 
 The liquid rock issuing from a crater, and the same after 
 becoming cold and solid, is called lava. 
 
 An active crater, even in its most quiet state, emits vapors. 
 These vapors are mostly simple steam, or aqueous vapor; 
 but in addition there are usually sulphur gases, and some- 
 times carbonic acid or muriatic acid. 
 
 In a time of special activity, fiery jets are sometimes 
 thrown up to a great height, which, in the distance, at night 
 look like a discharge of sparks from a furnace. These jets 
 are made of red-hot fragments of the liquid lava ; the frag- 
 ments cool as they descend about the sides of the crater, and 
 are then called cinders. 
 
 When a shower of rain, or of moisture from the condensed 
 steam, accompanies the fall of the cinders, the result is a 
 mud-like mass, which dries and becomes a brownish or yel- 
 lowish-brown layer or stratum called tufa. It is often much 
 like a soft coarse sandstone, only the materials are of vol- 
 canic origin. 
 
 The materials produced by the volcano are, then 1. 
 Lavas; 2. Cinders; 3. Tufas; 4. Vapors or Gases, which are 
 mostly vapor of water, partly sulphur gases, and in some cases 
 also carbonic acid, muriatic acid, and some other materials. 
 
 The lavas are of various kinds. They are more or less 
 cellular; sometimes light cellular, like the scoria of a furnace; 
 but more commonly heavy rocks with some scattered ragged 
 cellules or cavities through the mass. A stream of lava in 
 a crater, of this more solid kind, has often a few inches of 
 
304 DYNAMICAL GEOLOGY. 
 
 scoria at top, as a running stream of syrup may have its 
 scum or froth. The most of the scoria has this scum-like 
 origin. Pumice is a very light grayish scoria, full of long 
 and slender parallel air-cells. 
 
 The lavas may be black or brownish, and greenish-black, 
 in color, and very heavy (specific gravity above 2.9), as the 
 Dolerite and Basalt, described on page 26 ; or they may be 
 rather light (specific gravity under 2.7) and grayish in color, 
 as trachyte and phonolite. Phonolite is a very compact felds- 
 pathic rock, giving a clinking sound under the hammer. 
 
 A volcanic mountain is made out of the ejected materials; 
 either (1) out of lavas alone; or (2) of cinders alone; or 
 (3) of tufas alone ; or (4) of alternations of two or more 
 of these ingredients. As the centre of the mountain is the 
 centre of the active fires, the ejections flow off or fall around 
 it, and hence the form of a volcanic peak necessarily tends 
 to become conical. 
 
 The average angle of slope of a lava-cone is from 3 to 10 ; 
 of a tufa-cone, 15 to 30 ; of a cinder-cone, 30 to 45 ; of 
 mixed cones, intermediate inclinations according to their 
 constitution. 
 
 B. Volcanic eruptions. 
 
 The process of eruption, though the same in general 
 method in all volcanoes, varies much in its phenomena. 
 The fundamental principles are well shown at the great 
 craters of Hawaii, the southeasternmost of the Hawaian 
 (or Sandwich) Islands. 
 
 1. Hawaian Volcanoes. 1. General description. Hawaii is 
 made up mainly of three volcanic mountains, two, Mount 
 Loa and Mount Kea, nearly 14,000 feet high; and one (the 
 western), Mount Hualalai, about 10,000 feet. Mount Kea 
 is alone in being extinct. The average slopes of the two 
 highest are well shown in figs. 369, 370, on page 302, fig. 
 369 representing Mount Kea and 370 Mount Loa. 
 
 Mount Loa has a great crater at top, and another 4000 
 
HEAT VOLCANOES. 
 
 305 
 
 feet above the level of the sea (at k, fig. 370). The latter is 
 the famous one called Kilauea, and also Lua Pele or Pele's 
 pit, Pele being, in the mythology of the Hawaians, the 
 goddess of the volcano. 
 
 The accompanying map of the southeastern portion of 
 
 Fig. 371. 
 
 Map of part of Hawaii. - 
 
 Hawaii shows the positions of Mount Loa and Mount Kea, 
 and of the crater of Kilauea,"' besides other craters at the 
 summit of Mount Loa, and tm the sides at P, A, B, C, K, &c. 
 2. Kilauea. The crater of Kilauea is literally a pit. It 
 is three miles in greatest length, and nearly two in greatest 
 breadth, and about seven and a half miles in circuit. It is 
 large enough to contain Boston proper to South Bridge, 
 three times over, or to accommodate 400 such structures as 
 St. Peter's at Eome. The pit has nearly vertical sides of 
 solid rock (made of lavas piled up in successive layers), and 
 is 1000 feet in depth after its eruptions, and 600 when most 
 filled with lavas (its present condition). The bottom is a 
 
306 DYNAMICAL GEOLOGY. 
 
 great area of solid lava ; and it may be surveyed from the 
 brink of the pit, even when in most violent action, as calmly 
 sand safely as if the landscape were one of houses and 
 gardens. In some parts of it there are ordinarily one or 
 more lakes or pools of liquid lava, and from these and 
 other points vapors rise. The largest lake is sometimes 
 1000 feet or more in diameter. 
 
 3. Action in Kilauea. The action is simply this. The 
 lavas in the active pools are in a state of ebullition, jets 
 rising and falling as in a pot of boiling water, with this dif- 
 ference, that the jets are 30 or 40 feet high. Such jets, in 
 lava as well as water, arise from the effort of vapors to 
 escape ; in water the vapor is steam derived from the water 
 itself; in lavas it is steam and other gases from materials in 
 the lavas. 
 
 The lavas of the pools or lakes overflow at times and 
 spread in streams across the great plain that forms the 
 bottom of the crater. In times of great activity the pools 
 and lakes are numerous, the ebullition incessant, and the 
 overflowings follow one another in quick succession. 
 
 4. Cause of eruption. By these overflows the pit slowly 
 fills, and in the course of a few years the bottom is, conse- 
 quently, 400 feet above its lowest level ; so that the depth 
 is thus reduced from 1000 to 600 feet. This addition of 400 
 feet increases 400 feet the height of the central column of 
 liquid lava of the crater, and causes a corresponding increase 
 of pressure against the sides of the mountain. The amount 
 of this pressure is at least two and a half times as great as 
 that which an equal column of water would produce. The 
 mountain should be strong to bear it. The lavas at such 
 times may be in a state of violent activity, and when so 
 there is an addition to the pressure against the sides of the 
 mountain, arising from the force of the imprisoned vapors. 
 
 The consequence of this increase of pressure, both from 
 the lavas and the augmented vapors, may be, and .has several 
 
'HEAT VOLCANOES. 307 
 
 times been, a breaking of the sides of the mountain. One 
 or more fractures result, and out flows the lava through 
 the openings. Thus simple are the eruptions of the Hawaian t 
 volcanoes. 
 
 In one such eruption the lavas first appeared at the 
 surface a few miles below Kilauea (at P, fig. 371), and then 
 again at other points more remote, A, B, C, m; and finally 
 a stream began at n, a point 20 miles from the sea, which 
 continued to the shores at Nanawale. Here, on encounter- 
 ing the waters, the great flood of lava was shivered into 
 fragments, and the whole heavens were thick with an illu- 
 minated cloud of vapors and cinders, the light coming from 
 the fiery stream below. 
 
 This eruption of Kilauea took place, it will be observed, 
 not over the sides of the crater, but through breaks in the 
 mountain's sides below; and the pressure of the column of 
 lava within, along with the pressure of the escaping vapors, 
 appear to have caused the break. In all known eruptions 
 of Kilauea the process has been that described. 
 
 5. Summit-crater of Mount Loa. Eruptions have also taken 
 place within a few years from the summit-crater of the same 
 mountain (Mount Loa), or at a point nearly 14,000 feet high 
 above the sea; and in each case there has been, not an over- 
 flow from the crater, but an outflow through breaks in the 
 sides of the mountain. In one case there was first a small 
 issue of lavas near the summit, and then another of great mag- 
 nitude about 10,000 feet above the sea-level. At this second 
 outbreak the lava was thrown up in a fountain, or mass of 
 jets, several hundred feet high; and thus it continued in 
 action for several days. The forms of the fountain of liquid 
 fire were compared by Eev. Mr. Coan to the clustered spires 
 of some ancient Gothic cathedral. 
 
 6. Cause of the jet or fountain of lava. The pressure pro- 
 ducing this jet was that of the column of lava between the 
 point of outbreak and the level of the lavas in the summit- 
 
 27 
 
308 DYNAMICAL GEOLOGY. 
 
 crater 3000 to 4000 feet above. The same pressure in con- 
 nection with confined vapors must have caused the breaking 
 *of the mountain in which the eruption began. There have 
 been no great earthquakes accompanying the Hawaian erup- 
 tions, sometimes not even slight ones, the first announce- 
 ment being merely " a light on the mountain." Moreover, 
 when the summit-crater has been thus active, Kilauea, 
 though 10,000 feet lower on the same mountain and even a 
 ' larger pit-crater, has shown no agitation and no signs what- 
 ever of sympathy. 
 
 7- Conclusions. These cases of eruption indicate (1) that 
 the lavas go on gradually increasing the pressure in the 
 interior by their accumulation and rising to a higher level ; 
 and that finally, when the mountain can no longer resist it, 
 it breaks and lets the heavy liquid out. They show (2) that 
 while earthquakes may attend volcanic action, they are no 
 necessary part of it. They show (3) that lavas may be so 
 very liquid that no cinders are formed during a great erup- 
 tion. For in the ebullition of the lava in the boiling lakes 
 of Kilauea, the jets (made by the confined vapors) are thrown 
 only to a height of 30 or 40 feet ; and on falling back, the 
 material is still hot and does not become cooled fragments; 
 it either falls back into the pool or lake, or becomes plastered 
 to its sides. 
 
 At some of the eruptions of Mount Loa the lava has con- 
 tinued down the mountain to a distance of 30 or 40 miles. 
 
 2. Vesuvius. Vesuvius is an example of another type of 
 volcano. The lavas are so dense or viscid that jets cannot 
 rise freely over the surface : the vapors are kept confined 
 until they form a bubble of great dimensions ; and when such 
 a bubble, or a collection of them, bursts, the fragments are 
 sometimes thrown thousands of feet in height. The crater, 
 at a time of eruption, is a scene of violent activity, and can- 
 not be approached, Destructive earthquakes often attend 
 the eruptions. 
 
HEAT VOLCANOES. 309 
 
 The lavas at Vesuvius may flow directly from the top of 
 the crater ; but they generally escape partly, if not entirely, 
 through fissures in the sides of the mountain. 
 
 3. Comparison of Mount Loa and Vesuvius as to causes of 
 eruption and nature of the mountains, Of the two causes of 
 eruption hydrostatic pressure and elastic force of confined 
 vapors the latter may be the most effective at Vesuvius, 
 while the former is so at Hawaii. Mount Loa on Hawaii is 
 an example of the great free-flowing volcanoes of the world, 
 and the mountain is almost wholly a lava-cone. Vesuvius is 
 an example of a smaller vent with less liquid lavas; and the 
 cone is made up of both solid lavas and cinders. 
 
 4. Lateral cones of volcanoes. In eruptions through fissures 
 the lavas may continue issuing for some days or weeks 
 through the more open or widest part of the fissure, and 
 consequently form at this point a cone of cinders or lavas. 
 Thus have originated innumerable cones on the slopes of 
 Etna and other volcanic mountains. 
 
 5. Submarine eruptions. The eruptions may sometimes 
 take place from the submarine slopes of the mountain when 
 it is situated near the sea, as has happened with Etna and 
 Mount Loa ; and in such cases cones of fragmental lavas or 
 solid layers may form under water about the opened vent. 
 Fishes and other marine animals are usually destroyed in 
 great numbers by such submarine eruptions. 
 
 6. Subsidences of volcanic regions Overwhelming of cities. 
 Among the attendant effects of volcanoes are the sinking 
 of regions in their vicinity that have been undermined by 
 the outflow of the lavas, and the tumbling in of the summit 
 of a mountain. Another is the burial, not only of fields 
 and forests, but even of cities and their inhabitants, by the 
 outflowing streams, or the falling cinders and accumulating 
 tufas. Pompeii and Herculaneum are two of the cities that 
 have been buried by Vesuvius; and every few years we 
 
310 DYNAMICAL GEOLOGY. 
 
 hear of some new devastations made on habitations or farms 
 by this uneasy volcano. 
 
 C. Subordinate volcanic phenomena, 
 
 1. Solfataras. In the vicinity of volcanoes, and sometimes 
 in regions in which no volcanoes exist, there are areas where 
 steam, sulphur vapors, and perhaps carbonic acid and other 
 gases, are constantly escaping. Such areas are called sol- 
 fataras. The sulphur gases deposit sulphur in crystals or 
 incrustations about the fumaroles (as the steam-holes are 
 called) ; and alum and gypsum often form from the action 
 of sulphuric acid (another result from the sulphur gases) on 
 the rocks. 
 
 Fountains or springs of hot waters are common in such 
 places, and are often so abundant as to be. used for baths. 
 
 2. Geysers. In Iceland at the Geysers the heated waters 
 are thrown out in intermittent jets in some cases to a height 
 of 200 feet. Subterranean streams arising in the mountains 
 are supposed to pass over heated rocks, and then to be forced 
 upward by the vapors produced by the heat. Such heated 
 waters act on the rocks, decomposing them, and thereby 
 become slightly alkaline and also siliceous solutions. The 
 silica thus taken into solution is deposited again around the 
 Geysers in many beautiful forms, besides making the bowl 
 of the cavity or basin from which the waters are thrown 
 out, and forming numerous petrifactions. 
 
 When the basin of a boiling pool consists of earth or 
 mud, mud-cones are formed, as in California. 
 
 2. IGNEOUS ERUPTIONS NOT VOLCANIC. 
 
 It has been stated that eruptions of volcanoes generally 
 take place through fissures. Fissures have often been made 
 in the earth's crust and filled with liquid rock, also, in 
 regions remote from volcanoes. Such fractures of the crust 
 of the earth must have descended to some seat of fires, if 
 
NON-VOLCANIC IGNEOUS ERUPTIONS. 
 
 311 
 
 not through to the earth's liquid interior. Whatever cause 
 was sufficient to break through the crust would have sufficed 
 to press out the liquid rock beneath. The narrow mass of 
 igneous rock which fills such fissures is called a dike (p. 30). 
 The igneous rock is generally without cellules or air-cavities; 
 or, if present, they are neatly formed, and not ragged like 
 those of lavas. Such rocks having the cavities filled with 
 minerals (as quartz, zeolites, etc.) are called Amygdaloids. 
 
 The most common rocks of such dikes are dolerite and 
 basalt (p. 26), and next to these, diorite and porphyry. The 
 dolerite, basalt, and diorite are often called trap. 
 
 Dikes of rocks of this kind are mentioned and described 
 on p. 165 as occurring in various parts of the Eastern border 
 region of North America, constituting the Palisades on the 
 Hudson; Bergen HiU and other heights in New Jersey; 
 many bold bluffs- in Connecticut between New Haven and 
 its northern boundary; Mount Tom and Mount Holyoke 
 and other elevations in central Massachusetts, and ridges in 
 Nova Scotia near the Bay of Fundy. The rocks of the 
 Salisbury Craigs near Edinburgh, and of the Giants' Cause- 
 Fig. 372. 
 
 Basaltic columns, coast of Illawana, New South Wales. 
 
 way and Fingal's Cave, are other examples. They are 
 common on all the continents, especially in the regions 
 
 27* 
 
312 DYNAMICAL GEOLOGY. 
 
 between the summits of the border mountains and the 
 ocean, which are usually between 300 and 700 miles in 
 breadth ; as, for example, between the Appalachians and the 
 Atlantic, and between the Rocky Mountains and the Pacific. 
 These basaltic and doleritic rocks are often columnar in 
 their forms, as illustrated in the preceding sketch of a scene 
 in New South "Wales. The Giants' Causeway is remarkable 
 for the regularity of its columns. Similar scenes of great 
 beauty occur on Lake Superior, and some of less perfection 
 in the Connecticut River valley and the Palisades on the 
 Hudson. These columns were formed when the rock cooled, 
 and are due partly to contraction and partly to a concre- 
 tionary structure produced in the process of cooling. The 
 size of the concretions in such a case determines the diame- 
 ter of the columns, and depends on the amount of material 
 and the rate of cooling, the size being largjkthe slower the 
 
 rate. 
 
 3. METAMORPHISM, 
 
 1. Nature of metamorphism. The term metamorphism sig- 
 nifies change or alteration; and in Geology, a change in the 
 earth's rocks or strata, under the influence of heat below 
 fusion, resulting in crystallization, or, at least, firm solidifi- 
 cation : as when argillaceous shale is altered to roofing-slate 
 or mica schist; argillaceous sandstone, to gneiss or granite; 
 common compact limestone, to granular limestone or statuary 
 marble ; a common siliceous sandstone, to a hard grit or to 
 quartzite. The more common kinds of rocks resulting through 
 metamorphism are described on pages 23, 24. 
 
 2. Effects. The effects of metamorphism include not only 
 (1) solidification and (2) crystallization, but also 
 
 (3.) A change of color; as the gray and black of common 
 limestone to the white color or the clouded shadings of 
 marble ; and the brown and yellowish-brown of some sand- 
 stones colored by iron, to red, making red sandstone and 
 jasper-rock. 
 
METAMORPHISM. 313 
 
 (4.) In most cases, a partial or complete expulsion of 
 water, but not in all; for serpentine, a metamorphic rock, 
 is one-eighth (or 13 per cent.) water. 
 
 (5.) A partial or complete loss of bitumen, if this ingre- 
 dient be present; as when bituminous coal is changed to 
 anthracite or graphite (pp. 76, 160). 
 
 (6.) An obliteration of all fossils ; or of nearly all if the 
 metamorphism is partial. 
 
 (7.) In many cases, a change of constitution ; for the ingre- 
 dients subjected to the metamorphic process often enter 
 into new combinations : as when a limestone, with its impu- 
 rities of clay, sand, phosphates, and fluorids, gives rise under 
 the action of heat not merely to white granular limestone, 
 but to various crystalline minerals disseminated through 
 it, such as mica, feldspar, scapolite, pyroxene, etc.; or when 
 an argillaceous sandstone becomes a gneiss or schist full of 
 garnets, tourmaline, hornblende, etc. 
 
 Thus metamorphism often fills a i*bck with crystals of 
 various minerals. Even the gems are among its results; for 
 topaz, sapphire, emerald, ami diamond have been produced 
 through metamorphic action. What is* of more value, this 
 process makes out of rude shales and sandstones Bard and 
 beautiful crystalline rocks, as granite and marble, for archi- 
 tectural and other purposes. Man's imitations of nature in 
 this line are seen in his little red bricks. 
 
 3. Process. Water and heat are two agencies essential in 
 metamorphism. 
 
 Metamorphism has taken place generally when the rocks 
 were undergoing great disturbances or uplifts, foldings and 
 faultings, and, therefore, when the conditions were favor- 
 able for the escape of portions of the earth's internal heat. 
 This heat has penetrated the wet rocks. The water or 
 moisture within the rocks has rendered them good con- 
 ductors of heat, and has aided directly in conveying the 
 heat. Moreover, where the heat was above 212 F., or the 
 
314 DYNAMICAL GEOLOGY. 
 
 boiling point of water, as it probably has been in most 
 cases of metamorphic change, all of it has passed to what 
 is called a, superheated state; and in this state it -has great 
 power in dissolving and decomposing minerals and pro- 
 moting new combinations and crystallizations. Under such 
 circumstances, the moisture becomes itself a solution by 
 taking up mineral substances from the rock in which it is at 
 the time; and these added materials are the source of a 
 large part of its power in making changes ; for if it thus 
 becomes an alkaline siliceous solution, like the waters of 
 the Geysers (see p. 310), it may not only deposit quartz in 
 all seams or cavities, if the temperature favors this, but it 
 may, under other favorable circumstances, help in making 
 feldspars, micas^ and many other alkaline siliceous minerals; 
 or if the alkalies are mostly absent and iron is present, the 
 siliceous waters may promote the crystallization of stauro,- 
 tide and hornblende. 
 
 The change of a siftceous sandstone to a grit or quartzite 
 requires nothing but these conditions; for the moisture in 
 such a rock would become, when subjected to slow heating, 
 siliceous, from the material of the sandstone, and the silica 
 taken uj5 would be deposited again as the rock cooled, and 
 so cement and solidify the whole into a true quartzite. Such 
 quartzites often contain some feldspar, a mineral that would 
 also be formed if a little alkali and alumina were present. 
 
 These are examples of the various ways in which heated 
 and superheated waters may promote metamorphic changes. 
 Direct experiments have shown that these kinds of crystal- 
 lizations do result from the action of heat. 
 
 Pressure is requisite for most metamorphic changes. 
 Limestone heated without pressure loses its carbonic acid 
 and becomes quick-lime, as in a lime-kiln; but if under 
 pressure, the carbonic acid is not driven off. The possibility 
 of the crystallization of limestone by heat, under pressure, 
 has been proved by direct experiment. The necessary 
 
METAMORPHISM. 815 
 
 pressure may be that of an ocean above ; or it may be only 
 that of the superincumbent rocks, a few hundred feet of 
 which would be quite sufficient. 
 
 The similarity of argillaceous sandstones to gneiss or 
 granite is often much greater than appears to the eye. 
 They have been made by the wear of just such rocks as 
 gneiss and granite ; and the sand of the former is the quartz 
 of the -latter, the clay of the former frequently only the 
 pulverized feldspar of the latter, and mica may be in grains 
 in the former as it is in the latter : so that the change 
 would in such a case be mainly a change in the state of 
 crystallization. By heating a bar of steel to a temperature 
 far short of fusion, and cooling it again, it may be made 
 coarse or fine steel, the process changing the grains by 
 causing many small grains to combine to make the large 
 ones in the coarser kind and the reverse fo* the finer kind. 
 There is something analogous in the change of an argil- 
 laceous sandstone to a gneiss or granke above described. 
 
 If the sandstone or shale contains little or no alkali, its 
 metamorphism cannot produce a gneiss or mica slate, since 
 feldspar, one of the constituents of thes rocks, contains an 
 alkali as an essential ingredient. The result will necessarily 
 vary with the constituents of the original rock, and the 
 heat and other conditions attending the metamorphism. 
 
 Often, however, the material derived from the wear of 
 gneiss and granite and other rocks is not only pulverized, 
 but also more or less decomposed : the feldspar, for 
 example, undergoes a change in its alkalies, or loses 
 them altogether, they being carried off by waters, or the 
 mica may lose its oxyd of iron and alkalies; or waters 
 may bring in oxyd of iron or other ingredients ; and so on : 
 and in such a case the process of metamorphism could 
 not, of course, restore the original rock. The new rock 
 made would contain no feldspar if the alkalies had been 
 removed ; but it might be an argillite, or, if much oxyd of 
 
316 DYNAMICAL GEOLOGY. 
 
 iron were present, a hornblende rock, or some other kind, 
 according to the nature of the material subjected to the 
 change, and the amount or continuance of the heat. 
 
 Examples of the metamorphism of extensive regions of 
 the earth have already been mentioned on pages 75, 156, 
 and these pages should here be perused anew. In the case 
 of the Azoic formation, the rocks of a large part of the 
 earth's surface may have been in process of crystallization 
 at one time ; and in that of the Appalachian chain changes 
 of this kind took place not only over the region from Labra- 
 dor to Alabama, but simultaneously in Europe and probably 
 <m the other continents. 
 
 4. FORMATION OF VEINS. 
 
 1. Nature and origin of spaces occupied by veins. Yeins 
 occupy (1) the cracks and fissures made in rocks and (2) 
 openings between their layers, especially those of schistose 
 or slaty kinds. They are produced in great numbers when 
 a region of rocks is undergoing uplift, or when a folding 
 of the strata is in progress. The fractures may descend 
 through the crust, or to regions of melted rock, as in the 
 case of the formation of dikes (p. 310) ; they may descend 
 to depths of intense heat without reaching liquid rock 
 below; they may intersect either several strata lying to- 
 gether, or only one of a series, for some rocks will become 
 fractured by the same circumstances that will leave others 
 unbroken. 
 
 2. Filling of veins. Whatever the cause of the fractures, 
 the causes that produce so great metamorphic changes 
 would fill the fissures and openings (when not so deep as to 
 reach to regions of liquid rock) with minerals from the rock 
 either side of the fissure. The heated waters, or moisture, 
 of the rocks would slowly fill all cavities. A movement in 
 the moisture toward any empty space would take place ; 
 and the moisture of the rock around, on reaching the space 
 
FORMATION OF VEINS. 317 
 
 or fissure, would lose its mineral material by its crystalliza- 
 tion against the walls ; the place of that which was thus 
 lost would be resupplied at once by other portions, with the 
 same result; and thus a constant current would be kept up 
 as long as the supply held out, or until the cavity or fissure 
 were filled. In the filling of veins, the material comes mostly 
 from the rock adjoining some part of the fissure. 
 
 However minute the quantity of any material in the 
 adjoining rock, even if it be wholly undistinguishable by 
 any chemical investigation, the penetrating heated and 
 mineralized moisture would find it, and, taking it into solu- 
 tion, convey it to the forming vein. Gold, and the material 
 of emeralds and other metals and gems, have thus been 
 gathered into veins. 
 
 The kind of crystallizations in the fissure would depend 
 largely on the heat present and the nature of the rock 
 adjoining; and the heat would depend on the depth of the 
 fissure. If the vein reached down to depths of intense 
 heat, where cooling would be exceedingly slow, the materials 
 would be more coarsely crystallized than if only to shallow 
 depths. 
 
 Metallic ores may often rise in the fissures, in vapors or 
 solutions, from depths far below those at which they are 
 deposited. 
 
 Some strata, owing to their nature, might aiford almost 
 nothing for the fissure, and the filling of this part would 
 then come from the portions above or below. 
 
 3. Simple and banded veins. Yeins filled by this lateral 
 inflow of material would sometimes be uniform in texture 
 throughout, as in many quartz veins or seams; or they 
 might be banded, like most metallic veins (p. 30). In the 
 formation of the latter, the infiltrating process might bring 
 in for a while one kind of mineral, as feldspar, and deposit 
 it over the walls of the fissure ; then, through a modification 
 of the temperature, or some other change, quartz; then, an 
 
318 DYNAMICAL GEOLOGY. 
 
 ore of lead, or one of zinc, or one of copper; then quartz 
 again, or calcite ; and so on until the vein was filled. 
 
 In, these ways argillaceous and talcose schists have been 
 filled with quartz veins or seams, the repositories of gold 
 and of various ores. (These auriferous quartz veins in 
 schists are often only the filling of cavities opened between 
 the layers, and which are due to the contortions the schists 
 underwent during the uplifting, folding, and metamorphic 
 process.) By similar methods granitic and various metallic 
 veins have been formed in rocks of other kinds. 
 
 Thus the earth's metals have been gathered from rocks, 
 in which they were disseminated in such infinitesimal quan- 
 tities as to be of no service to art, into generous veins, and 
 so placed within reach of the miner. 
 
 Y. MOVEMENTS IN THE EABTH'S CEUST, AND 
 THEIE CONSEQUENCES. 
 
 The subjects here included are the following : 
 
 1. Origin of changes of position and level in the earth's 
 crust or rocks. 
 
 2. Origin of cleavage and jointed structure in rocks. 
 
 3. Earthquakes. 
 
 4. Origin of the earth's general features, and of the suc- 
 cessive phases in its history. 
 
 1. CHANGES IN POSITION AND LEVEL. 
 
 Change of level may proceed from undermining, either by 
 subterranean waters (p. 281), or by volcanic ejections (p. 
 309). But the results of these causes are comparatively 
 local. 
 
 The causes of more comprehensive character, usually ap- 
 pealed to in order to explain the origin of the earth's moun- 
 tains and its oscillations of level, are the following : 
 
 1. Vapors suddenly evolved beneath some portion of the earth's 
 crust. This cause has been commonly regarded as of the 
 
CHANGES OF LEVEL. 319 
 
 highest importance, especially with reference to the eleva- 
 tion of mountains. There are two difficulties with regard 
 to it. (1.) No open cavities of sufficient extent for the. pur- 
 pose can be proved to exist beneath mountains where such 
 vapors could spread and act. (2.) If the explosion were to 
 take place, as, for example, beneath the Andes, the 
 mountains would not stay up on a mere bed of condensible 
 vapors ; they are very heavy, and require solid support. 
 
 2. Weight of the accumulations of sedimentary formations in 
 progress over any region, as the Appalachian. This cause 
 might possibly produce subsidence in a region like the 
 Appalachians, and some uplifts either side as a secondary 
 effect from the lateral pushing which such a subsidence 
 might occasion. But, although the subsidence in the Appa- 
 lachian region greatly exceeded the elevations (p. 155) there 
 were some elevations alternating with the subsidences in 
 the course of the Paleozoic ages ; and, later, in the progress 
 of the formation of the mountains, a series of flexures on a 
 great scale, over the whole breadth of the region, w r as pro- 
 duced in addition to elevations (p. 156) ; and such effects 
 cannot proceed from mere weight or gravitation. 
 
 3. Expansion and contraction 'from change of temperature. 
 If a portion of the crust, or of its rocks, becomes heated 
 from the action of heat below, elevation will result, because 
 an increase of heat causes expansion; and expansion must 
 show itself in a rising of the surface. Conversely, if a 
 heated region cools, there will be contraction ; and this con- 
 traction may cause two effects : (1) a sinking in the surface; 
 (2) a fracturing of the rocks, or shrinkage-cracks. If there 
 are no fractures produced, the whole result will appear in 
 the sinking. 
 
 This cause of change of level acts with extreme slowness. 
 
 The subsidence and elevation of the region of the Temple 
 of Serapis, on the coast of Italy just north of Naples, have 
 been attributed to this cause. 
 
 28 
 
320 DYNAMICAL GEOLOGY. 
 
 4. Tension in the earth's crust resulting from the contraction 
 of the globe. In the remarks on the Appalachian revolution 
 (p. 16J)), it was shown that the effects proved beyond ques- 
 tion (1) the action of lateral pressure ; (2) that this lateral 
 pressure was exerted in the earth's crust, and in a direction 
 from the Atlantic Ocean, or at right angles to the course of 
 the mountains ; (3) that it was exceedingly slow or gradual 
 in action. This slow-acting pressure, as in the third cause 
 above explained, is a power residing, through some cause, 
 in the crust itself of the earth. 
 
 The facts observed in the Appalachians are common facts 
 all over the globe wherever there are uplifted rocks or 
 mountains. Nearly all tilted rocks are actually folded 
 rocks. The flexures vary in extent from the slightest arch- 
 ing of the strata to bold and lofty close-pressed folds, as 
 illustrated on pages 41, 42. This flexed condition could 
 have been produced only by lateral action or pressure, as a 
 result of the cause alluded to. This cause has, therefore, 
 produced universal effects over the globe. 
 
 The facts in Geology leave little room for doubt that the 
 earth was once in fusion, and has been through all time a 
 cooling globe. If it has been a cooling globe, it has been 
 undergoing contraction, or a gradual diminution of size, 
 just as a globe of glass or lead will become smaller on slow 
 cooling. Now, in the case of a cooling sphere, if an exterior 
 hard crust be early formed, the contraction afterwards going 
 on within will bring a great strain on this crust, because it 
 is unyielding and cannot accommodate itself to the contrac- 
 tion in progress ; and this strain, if the crust be not thick 
 enough to stand firm, will result either in breaking the 
 crust and pulling inward some portions and so pressing 
 other parts out, or in making the crust to rise into folds. 
 In a drying, and therefore contracting, apple, the skin 
 becomes folded, because flexible. In a drop of glass (called 
 a Prince Eupert's drop) which has been formed by rapid 
 
CHANGES OF LEVEL. 321 
 
 cooling (the outside thereby being first cooled), the whole 
 is under powerful tension or strain. The exterior is so hard, 
 of so uniform texture, and of so even surface, that it cannot 
 become folded, and yet it remains unbroken; but if the 
 faintest scratch of a Je be made, so as to disturb the equi- 
 librium in the mass, the whole goes to fragments, even with 
 explosion. The scratch of the file takes out particles from 
 the surface, and acts like the taking out of a line of stones 
 from a heavily weighted arch ; the destruction is in principle 
 the same as in the case of the arch. 
 
 In a cooling sphere like the earth there must have always 
 been a tension or strain in the crust from this cause ; and, 
 as the earth is not a glass globe of even texture and surface, 
 the cause should have produced fractures and flexures, 
 bulgings and sinkings, over its various parts, and at various 
 times in the course of the earth's history; while gentle oscil- 
 lations of level in the crust must have been in constant 
 progress. 
 
 5. Sufficiency of the last-mentioned cause. This cause is a 
 sufficient cause for all flexures of strata, because it is indefi- 
 nite in power and very slow in its action. A sudden force 
 would throw strata into a chaos. But experiment has proved 
 that by an exceedingly gradual movement any bed of rock, 
 however inflexible, especially if moistened and heated, and 
 even cold ice, may be made to rise into an arch, and then 
 into a series of arches or folds, by a slowly acting lateral 
 pressure. 
 
 This cause is one that affords a firm support for the lifted 
 continent or mountain-chain as it rises; for in its action 
 one portion of the earth's crust is pushed up by another, and 
 the former, therefore, rests on the mass by means of which 
 it w T as raised. It remains where it is placed by the irresist- 
 ible pressing force. 
 
 This cause is sufficient to have made the mountains 
 of the globe. Mountains are relatively very small eleva- 
 
322 DYNAMICAL GEOLOGY. 
 
 tions on the earth's surface. Etna, although 10,000 feet 
 high, would stand up but one-tenth of an inch on a globe 
 110 feet in circumference, or 35 feet in diameter, as 
 large as many a capacious house ; and one-hundredth of an 
 inch would correspond on such a globe to 1000 feet, which 
 is the mean height of all the continents. The wrinkles on 
 an orange are proportionally larger than those of the earth 
 or her mountains : the earth has relatively the smoother 
 surfade. 
 
 It is obvious, therefore, that the height or extent of 
 mountain-elevations is no difficulty before such a force as 
 that contemplated. Chains as lofty as the Himalayas, 
 valleys as deep as the profoundest oceanic basin, flexures as 
 numerous and close as those of the Appalachians, Juras, and 
 other chains, and fractures and faults thousands of feet in 
 depth, may all proceed from this one universal and ever- 
 acting cause. The changes of level now in progress in 
 Sweden, Greenland, and some other northern regions, may 
 be due to its present power. 
 
 6. Change of water-level may be caused by change of level in 
 the bottom of the oceanic basins. Changes of level are ordi- 
 narily measured by reference to the water-level, that is, the 
 level of the ocean. Thus, if a region is 100 feet above the 
 ocean in one period and 200 in a following, the first inference 
 is that the land has been elevated 100 feet. It is plain, 
 however, that this inference is correct only in case the 
 bottom of the ocean has remained unchanged in level. The 
 oceanic area is three times as large as that of the continents; 
 and if the earth's crust beneath the oceans were to sub- 
 side until the average subsidence was 200 feet, the water- 
 level would sink away from the land to a level 200 feet 
 below the present level. There is no reason why the oceanic 
 part of the crust should not have been as liable to change 
 of level by subsidence as that of the land by elevation ; in 
 fact, there is strong evidence for believing, as mentioned 
 
SLATY CLEAVAGE AND JOINTS. 323 
 
 beyond, that the oceanic basin has always been the more 
 sinking portion of the crust, or that most subject to subsi- 
 dence. It is, therefore, essential for accurate conclusions, in 
 cases of apparent elevation, that the possibility of changes 
 over the oceans should be considered. It is probable that 
 the present average height of the continental lands above 
 the ocean, or 1000 feet, is wholly owing to the sinking of 
 the ocean's bed which was in progress through the successive 
 geological ages. 
 
 2. SLATY CLEAVAGE AND JOINTS. 
 
 1. Slaty cleavage. On page 36 it has been stated that the 
 lamination, or slaty cleavage, of the great beds of roofing- 
 slate does not, as in shales, conform in direction to the 
 original layers or beds, but, on the contrary, is oblique to the 
 bedding and sometimes nearly at right angles to it. As 
 slates were originally shales, some change has come over 
 them in the process of metamorphism, which has almost 
 or quite obliterated the original lamination and produced 
 another in a new and transverse direction. 
 
 The shales during a metamorphic process are not only 
 hardened and rendered, it may be, semi-crystalline, but they 
 are also uplifted or folded. This uplifting and folding is a 
 result of long-continued lateral pressure, as explained on 
 the preceding pages. The slaty cleavage results directly from 
 the lateral pressure attending the uplifting and flexing, and 
 is at right angles to the direction of the pressure. Tyndall has 
 found that even beeswax may be rendered lamellar in 
 structure by pressure alone; and if this is possible with a 
 substance of so uniform texture as beeswax, there is no 
 question about it with regard to clayey rocks. The pressure 
 tends to force all lamellar particles, as scales of mica, or 
 flattened grains of sand, into parallel planes having the 
 direction just stated, and also to flatten out all air-spaces in 
 the same direction ; and in these ways the pressure is enabled 
 
 28* 
 
324 DYNAMICAL GEOLOGY. 
 
 to produce the slaty structure. The same structure actually 
 exists an the ice of many glaciers, and from essentially the 
 same cause. 
 
 2. Joints. Joints in rocks are described on page 35 as 
 planes of fracture descending to great depths, and as being 
 systematically parallel in the same region, and also in great 
 numbers. This parallelism is similar to the parallelism in 
 the slaty structure, and both have the same origin, the 
 lateral pressure attending movements in the earth's crust. 
 Joints occur in rocks of any kind, even coarse conglomerates 
 and granites as well as sandstones, limestones, slates, and 
 shales, and also in rocks that are not inclined or but little 
 so. While the slaty structure is an effect of successive 
 movements in the action of pressure, the joints may proceed 
 both from such movements and from a simple yielding to a 
 progressing tension or strain. This force, acting from a 
 common direction through a long period, produces in the 
 end a series of deep fractures, parallel in course and there- 
 fore one in system. Other joints at right angles to this 
 system may result simultaneously, making a transverse 
 system. Or the action of the same force in a later period 
 or age, from a different direction, may cause a system of joints 
 oblique to the first. Thus, two or more systems of joints 
 may be produced in the rocks of the same region. 
 
 Joints and slaty cleavage are, therefore, effects of the 
 great and universal power which has caused the oscillations, 
 uplifts, and flexures in the earth's crust. 
 
 3. EARTHQUAKES. 
 
 1. Nature of earthquake-vibrations. Earthquakes are vibra- 
 tions in the material of the earth's crust. A shock or 
 concussion produced by a fracture or movement at any 
 point causes vibrations in the rocks, and these vibrations 
 travel outward from this point until they finally die out. 
 
EARTHQUAKES. 325 
 
 The vibrations in ice made by skaters may be heard for 
 miles if the ear be placed close to the ice, because these 
 vibrations travel far in a layer of such material. So it is, 
 also, in the earth's rocks, although they are of less even 
 texture and surface. 
 
 The vibrations are of different kinds: (1) a simple 
 shaking, without any actual displacement in the rocks; 
 (2) a more powerful vibration, where there are both a shaking 
 and a displacement, as when a shove, fault, or uplift sud- 
 denly takes place ; (3) very rapid vibrations, causing the 
 sensation of sound. 
 
 2. Effects of earthquakes over the land. Earthquakes are 
 well known to result often in the destruction of buildings, 
 or even cities; in the opening of profound cracks in the 
 ground, in which great numbers of people are sometimes 
 engulfed ; in the displacement of rocks and trees, and start- 
 ing of avalanches of gravel and stones down precipices. 
 
 3. Earthquake oceanic waves. An earthquake-vibration, 
 when communicated to the ocean, causes great and powerful 
 waves, which sometimes travel for thousands of miles. The 
 earthquake at Yaldivia on the coast of Chili, in 1837, pro- 
 duced a series of waves which deluged the eastern shores 
 of Hawaii, 6000 miles distant; and an earthquake in 1854, 
 at Simoda in Japan, sent waves across the Pacific to Oregon 
 and California, which were detected there by the self-regis- 
 tering tide-gauges of the Coast Survey. 
 
 Oceanic earthquake-waves, in 1746, swept up the coast of 
 Peru, and carried a frigate from the harbor of Callao several 
 miles over the land, besides sinking 23 vessels ; and during 
 an earthquake on the coast of Spain, in 1755, the sea rushed 
 up the land in a wave 40 feet high in the Tagus and 60 feet 
 at Cadiz ; and the same wave was 8 to 10 feet high on the 
 coast of Cornwall, England. 
 
 These earthquake-waves have been an agency of great 
 power and of very important results in the course of the 
 
326 DYNAMICAL GEOLOGY. 
 
 earth's ancient history, deluging the land, destroying life, 
 both of the sea and land, and sweeping away beaches and 
 stratified deposits. 
 
 4. Causes of Earthquakes. Whatever causes are capable of 
 producing changes of level or position in the earth's crust 
 may be causes of earthquakes. Thus, the undermining of 
 strata, the evolution of vapors about volcanoes, tidal or 
 other movements in the earth's liquid interior, tension 
 from change of temperature, as in local cases, or in the 
 earth's slow cooling, must have each produced their earth- 
 quakes. The last cause must have been the most common 
 and comprehensive, if it is the cause of the larger part of 
 the oscillations and uplifts over the earth. It may be the 
 cause of the more powerful and extensive earthquakes of 
 the present day, since tension within from the progress of 
 cooling cannot yet have ceased. The cracking sounds in a 
 stove-pipe as a furnace is rapidly heating or cooling are 
 a result of that tension from expansion or contraction which 
 accompanies change of temperature; for there is a strain 
 produced, and then a yielding with loud sound. They 
 exemplify, on a small scale, the lighter kind of earthquakes 
 resulting from the earth's secular refrigeration. 
 
 According to Prof. Perrey of Dijon, there is some corre- 
 spondence between the occurrence of earthquakes and the 
 times of the ocean's tidal movements, and he infers, conse- 
 quently, that there are tides in the earth's interior liquid 
 corresponding to those of the ocean, making themselves 
 manifest in earthquake-vibrations. Further investigation 
 appears to be required to establish this as an actual cause 
 of earthquakes at the present time. 
 
 4. ORIGIN OF THE EARTH'S GENERAL FEATURES, AND OF 
 THE SUCCESSIVE PHASES IN ITS HISTORY. 
 
 1. General laws as to the Earth's features. 
 The first two of the following laws have been stated and 
 
EVOLUTION OF THE EARTH'S FEATURES. 327 
 
 explained on pages 8 to 11. The others are illustrated in 
 the course of the volume. It should be understood that the 
 border region of a continent includes the ridges of the border 
 mountains and the country which lies between them and 
 the adjoining seacoast. Thus, the western border region 
 of North America is that lying between the summits of the 
 Eocky Mountains and the Pacific coast, an area 300 to 800 
 miles wide ; and the eastern as that extending from the 
 western ridges of the Appalachians to the Atlantic, an area 
 200 to 300 miles in width. 
 
 (1.) The continents have in general high borders and a 
 low interior, and are, therefore, basin-shaped. 
 
 (2.) The highest border faces the largest ocean. 
 
 (3.) The effects of heat after Azoic time are more marked 
 along the border regions of the continents than over their 
 interior. It is sufficient, in illustration of this law, to 
 refer to the fact that nearly all the metamorphism of North 
 American rocks, after that of Azoic time, took place either 
 in the Atlantic or the Pacific border regions ; and that the 
 volcanoes of this and the other continents, with a rare 
 exception, are confined, and have always been confined, to 
 the border regions of those continents, and are absent from 
 the interior regions. One exception exists in central Asia, 
 in the Thian-Chan Mountains. The volcanoes of Europe 
 and western Asia pertain to the region bordering on the 
 Mediterranean and Bed Sea. 
 
 (4.) The effects of heat are most marked on the border 
 region adjoining the largest ocean. This law is also exem- 
 plified on all the continents. The great ocean the Pacific 
 has a girt of volcanoes, as stated on page 300 ; the small 
 Atlantic, almost none. In North America a large number 
 of volcanoes, from 10,000 to 18,000 feet in height, exist in the 
 western border region, but not one east of the summit of 
 the Rocky Mountains; metamorphic rocks, and those 
 igneous rocks that have been ejected through fissures, are 
 
328 DYNAMICAL GEOLOGY. 
 
 almost the sole effects of igneous action found in the At- 
 lantic border region. 
 
 In South America there are similar facts : the volcanoes 
 of the Pacific border region are very numerous, and vary 
 from 25,000 feet in height to 10,000 and under. On the 
 Atlantic side there are none. In Africa there is a small 
 volcanic region on the coast adjoining the Gulf of Guinea, 
 in the Cameroons Mountains; but a number of large volca- 
 noes exist in eastern Africa through Abyssinia and the Red 
 Sea. 
 
 In the great Orient there are hundreds of volcanoes on 
 the Pacific side, in the outer range of heights constituting 
 the islands off the coast, as the Philippines, Japan, the 
 Kuriles, etc., and in Kamtchatka; but none on the coast of 
 Norway, and only a few small regions in Europe, and these, 
 as has been said, are connected with the Mediterranean 
 region. 
 
 (5.) The transverse mediterranean seas of the world abound 
 in volcanoes. The East Indies between Australia and Asia, 
 the Red and Mediterranean seas between Africa and Europe, 
 the West Indies, as well as Central America, between North 
 and South America, are notedly volcanic areas. The volca- 
 noes of the Mediterranean region occur in Spain, France, 
 Germany, Italy, Greece, Syria, and Armenia. 
 
 2. Origin of the Earths Features, and Phases of Progress. 
 
 1. The cause universal in action. The conformity of the 
 continents in their reliefs to one model (p. 9) proves some 
 common method of formation; and, as the continents occupy 
 one-third of the earth's surface, this method of formation 
 must have been dependent on some world-wide cause. 
 
 Since, moreover, the forms of the continents have a 
 direct relation to the extent of the ocean (a relation so close 
 that there is almost an exact proportion between the eleva- 
 tion of the border region of the continents and the capacity 
 
EVOLUTION OP THE EARTH'S FEATURES. 329 
 
 of the adjoining ocean), both must have resulted from the 
 same universal method of development. 
 
 2. Continents and oceans outlined in the beginning. The 
 making of the continents according to a model implies a 
 regular or systematic course of progress throughout the 
 earth's history. If the ocean and continents had at times 
 changed places (if Asia, for example, had ever been the area 
 of the deep- ocean, and the bed of the Pacific the dry land 
 of a continent, and thus oceans and continents had alter- 
 nated with one another), the comprehensive relation between 
 the extent of the oceans and the heights of the continental 
 borders would have been impossible. Direct observation 
 has proved, moreover, that the continent of North America 
 was in actual existence, and of nearly or quite its present 
 extent, by the close of the Azoic age, if not before (p. 84); 
 that, although mostly submerged, it lay in the Primordial 
 period near the surface, part constituting the Azoic dry 
 land, part rising as sand-banks, beaches, and dunes above 
 the tides, a large part in shallow waters within reach of 
 the waves, while other portions were at somewhat greater 
 depths. 
 
 The above proposition is proved also by the whole course 
 of geological progress, the great fact in which is that the 
 elevating and oscillating forces which were in action in 
 Azoic times continued to be, for the most part, the same in 
 direction through all subsequent time to the close of the 
 Tertiary. (See pages 77, 146, 245). 
 
 The law of form, the law of progress, and the law of rela- 
 tion to the oceans, each and all afford decisive proof, there- 
 fore, that the continents were fixed in their positions in 
 the beginning, and determined at the same time, also, in 
 their main outline; and, if the outlines of the continents 
 were fixed, those of the oceans were so also, since they are 
 one and the same. 
 
 3. Oneness of the cause. One cause acting continuously 
 
330 DYNAMICAL GEOLOGY. 
 
 from the beginning of the earth's crust to the end of geolo- 
 gical history has, therefore, originated by concurrent move- 
 ments the oceanic basin and the continental plateaus. This 
 cause has not merely raised the continental areas and sunk 
 the oceanic. It has made their mountains and their plains. 
 It has evolved, not isolated or scattered heights, but heights 
 in ranges and chains, and placed them with so much system 
 over the surface that a continent has as truly its type of 
 form as an animal. In each case there is the same evidence 
 of a system of evolution or development, starting from a 
 condition of memberless simplicity, and ending in a complex 
 structure in which every part has harmonious reference to 
 a specific purpose. 
 
 4. Nature and mode of action of the cause. In explaining 
 the origin of mountains, the complete efficiency and uni- 
 versality of one great cause was pointed out. This cause 
 contraction from cooling appears to have all the require- 
 ments, as far as they can reside in any physical cause, that 
 are necessary for the grander result here in view, the 
 development of the earth's physical features. It has acted 
 uninterruptedly through all time. It must have acted 
 with simultaneous and accordant results throughout the 
 whole crust, oceanic and continental. But, while every- 
 where in simultaneous and systematic movement, there 
 have been produced a diversity of effects, and a diversity 
 under system. 
 
 In a cooling globe, the part which earliest became cold 
 and rigid would not afterwards yield, under the influence 
 of the progressing contraction, as readily as the rest, and 
 would therefore remain comparatively firm while the other 
 part was gradually subsiding. There might hence be from 
 the first a firmer or more stable portion, and a sinking or 
 depressed portion; and thus would begin the continental 
 and the oceanic areas. The waters of such a globe would be 
 
EVOLUTION OF THE EARTH'S FEATURES. 831 
 
 deepest in the depressed portion, if not wholly contained 
 within it. 
 
 If, then, the oceanic portions of the crust were the great 
 contracting areas, and the continental plateaus the parts 
 comparatively stable, or those contracting least, the sinking 
 of the crust of the former would bring the greatest strain 
 against the borders of the rigid portion, that is, the borders 
 of the continental plateaus. Here, therefore, the lateral press- 
 ure or pushing action *would show its greatest effects : 
 (1) in upliftings of the crust ; (2) in foldings and fractures ; 
 
 (3) in metamorphism through escaping internal heat; 
 
 (4) in igneous ejections through fissures and volcanic vents. 
 The continents subjected to such a force would have their 
 border regions elevated thereby, and would thus receive 
 that basin-like shape which characterizes them. Moreover, 
 as the deepest and largest oceanic basin is a result of the 
 greatest amount of contraction over the largest area, the 
 mountains on the border of the largest ocean would be 
 highest, the fractures deepest, and the volcanoes, since they 
 are opened over deep fractures, most numerous, as have 
 been shown to be true (pp. (10, 300). 
 
 The cause considered may also produce mountains over 
 the interior of a continent, as it does minor uplifts, and 
 especially so if the continent be of great breadth. For con- 
 traction must have been ever in progress beneath the con- 
 tinental plateaus, as well as the oceanic basin. It is hence 
 natural that the great Orient, 6000 miles in width from 
 Britain to Japan, should have its Urals as a nearly north 
 and south chain between Europe and Asia. 
 
 The facts and the theory seem thus to be in unison. 
 There can be no doubt that plications, fractures, and moun- 
 tain-lifting have resulted through tension or lateral pressure 
 in the crust from some cause. No cause of such tension 
 has been pointed out but that of gradual contraction 
 through the cooling of the earth. The cause would give 
 
 29 
 
332 DYNAMICAL GEOLOGY. 
 
 systematic results; it would produce general uniformity of 
 action and progress through successive ages ; and it would 
 lead to that family likeness which subsists between the 
 continents, while admitting also of those diversities which 
 distinguish them. 
 
 5. Catastrophes and revolutions, or abrupt transitions in his- 
 tory, A cause producing the oscillations of the earth's crust 
 and the elevation of mountains would also occasion catas- 
 trophes to the life of the globe, and abrupt transitions in 
 the series of strata. 
 
 If the raising of a continent from the ocean, or of a large 
 portion of it, were to take place under the action of such a 
 cause, an extinction of marine life would be a necessary 
 consequence; or, if a sinking of a continent beneath the 
 waves should occur, an extinction of terrestrial life would 
 result. Changing simply the depth of the water might also 
 cause extinctions, since the oceanic species living between 
 high and low tide level (or in the littoral zone, as it is called) 
 are mostly different from those below; and those living 
 between low-water and 90 feet (or in the Laminarian zone) 
 are almost all different from those of greater depths. 
 
 These oscillations might cause the extinction of life, also, 
 by changing the climate of the globe, as explained on page 
 256. 
 
 Moreover, all changes of level, causing submergence or 
 emergence of the land, or even varying the depth of water, 
 would change more or less the courses of currents in the seas 
 and the region of wave-action, and would consequently 
 change the kinds of rocks in progress, as from sand-beds to 
 shales, or to conglomerate, and the reverse. Again, an 
 extermination of the animal life (corals, crinoids, &c.) of a 
 continental sea by any oscillation or other cause would stop 
 the formation of limestones ; and the extermination (as by 
 submergence) of the plants of the land would cut short the 
 coal-plant accumulation, to be resumed again only when 
 
333 
 
 the land should be anew in a condition to grow the terres- 
 trial vegetation of marshes. 
 
 Under such a cause, there would be, at long intervals, 
 epochs of grander catastrophes, resulting in mctamorphism, 
 in great fractures and foldings, and in the raising of moun- 
 tains. The tension arising from contraction in such a crust 
 would go on accumulating for long periods before it' would 
 be sufficient to overcome the resistance and cause great 
 disturbances ; and when a yielding finally took place, then 
 the grander series of catastrophes would happen. There 
 was one grand epoch of general metamorphism and folding 
 at or near the close of the Azoic. Through the Paleozoic 
 there were various oscillations of level, and, at a few times, 
 disturbances and uplifts, with probably some metamorphism 
 (as in the Green Mountains after the Lower Silurian) ; but 
 no general epoch of change occurred in eastern North 
 America or over the world until the close of the Paleozoic, 
 when the Appalachian revolution took place. 
 
 After this epoch of the Appalachian revolution, there 
 were, through Mesozoic time, changes of level or uplifts of 
 limited extent; but not until the Cretaceous period was 
 drawing to its close did another grand epoch begin, the 
 one in which the life of the Cretaceous world ended, and 
 the great mountains of the continents were mostly made 
 (p. 202). 
 
 3. Illustrations from North America. 
 
 1. Simplicity of action in North America. The continent 
 of North America stands isolated from all others, having an 
 ocean on the east, an ocean on the west, the small Arctic 
 sea on the north, and the Pacific with partly the Atlantic 
 not South America on the south. It is, therefore, in the 
 best possible condition for exemplifying the law of origin of 
 the continental features. For if the extent of the oceans is 
 an approximate measure of the elevating forces engaged, 
 
334 DYNAMICAL GEOLOGY. 
 
 this open exposure to the ocean on all its sides should give 
 the forces their best opportunity for undisturbed or regular 
 results. 
 
 Europe, on the contrary, lies between oceans and conti- 
 nents, and is, therefore, complex in its rocks and mountains. 
 
 2. Method of action, and its progress. The two systems of 
 forces engaged in the progress of North America were those 
 of the Atlantic and Pacific, the latter the greatest. Under 
 their action the Y-shaped Azoic dry land (map. page 73) 
 was first defined, one branch stretching northeastward to 
 Labrador and the other northwestward to the Arctic, and 
 thus facing respectively the Atlantic and Pacific. It fol- 
 lows, from the courses of the arms of the Y, that the 
 Atlantic force acted mainly from the southeastward and 
 the Pacific from the southwestward, and the two, therefore, 
 nearly at right angles to one another. It is also apparent 
 that the Pacific force even then was the greater, and hence 
 the Pacific Ocean the larger; for the northwestward branch 
 of the Y is far the longer. 
 
 Thus the Azoic nucleus was outlined, and the portion of 
 Hudson's Bay determined within the arms of the Y. From 
 this nucleal dry land, progress went forward southeastward 
 or toward the Atlantic, and southwestward or toward the 
 Pacific, successive formations being added under gentle 
 oscillations, and the dry land gradually extending under 
 changes of level caused mainly by the same forces. Then, 
 when Paleozoic time was closing, appeared the Appalachian 
 chain and its many ridges parallel to the eastern branch of 
 the Azoic heights, and along the Rocky chain parallel to the 
 western branch ; thus doubling the Y, and proving that the 
 forces were still the same in direction as in Azoic time. 
 The Appalachian chain follows in its direction quite closely 
 the Azoic coast-line ; for the Green Mountain portion ex- 
 tends north and south, like the border of the Azoic penin- 
 sula in northern New York, and then the New Jersey and 
 
EVOLUTION OF THE EARTH'S FEATURES. 335 
 
 Pennsylvania portions bend around nearly to the east and 
 west, or parallel with the southern border of the New York 
 Azoic. South of this the chain takes again its normal 
 direction, or from northeast to southwest. Later still, rose 
 the trap ridges of the Mesozoic on the Atlantic border 
 (p. 165), making another parallel to the eastern branch, or 
 tripling the Y on the east, and even repeating all tho 
 Appalachian bends just mentioned. 
 
 Again, on the Pacific side, other ranges were made parallel 
 to the course of the Rocky Mountain chain ; among them, 
 the Sierra Nevada and Cascade range, the latter, with its 
 many volcanoes, adding new parallels to the western branch 
 of the Azoic. The mass of the Eocky Mountains also rose 
 to its full height above the ocean. 
 
 Each added range, as is seen, proves that the mountain- 
 making forces continued to act from the same directions as 
 in Azoic time. 
 
 The intersection of effects of the Atlantic and Pacific 
 forces may be distinguished over the interior of North 
 America; for the courses of the uplifts of the Coal formation 
 in Illinois and the trend of Florida are parallel to the Pacific 
 border, and the line between these two intersects the Appa- 
 lachian chain in eastern Tennessee. Again, there is an 
 uplift of the Lower Silurian about Cincinnati, which appears 
 to have been produced by the combined action of the two 
 forces; and it is of interest to note that the Pacific and 
 Atlantic forces here meet at a point which is four times 
 more distant from the coast of the Pacific or larger ocean 
 than it is from that of the Atlantic or smaller ocean. 
 
 Thus the continent made progress, adding layer after 
 Jayer to the rocks over its surface, and range after range 
 in parallel lines to its heights, until finally the continental 
 area reached its limit, and the great interior basin had 
 its mountain-borders completed : on the east, the low Appa- 
 lachians, and the trap ridges of the Mesozoic ; on the west, 
 
 29* 
 
336 DYNAMICAL GEOLOGY. 
 
 the massive and lofty Eocky chain, with its parallel crests 
 and ridges, and nearer the ocean a chain containing, north 
 of California (in the part called the Cascade range), a num- 
 ber of lofty volcanic peaks, and to the south (Sierra Ne- 
 vada) consisting mostly of metamorphic rocks. 
 
 It has been explained on page 234 that, when thus com- 
 pleted, there occurred an apparent change in the region 
 moved by the forces. The high-latitude oscillations of the 
 Post-tertiary began (p. 219). But the Pacific and Atlantic 
 forces may have occasioned these new movements. For if, 
 in the course of the changes though the geological ages, the. 
 portions of the continental crust in lower latitudes, thick- 
 ened by the successive formations, and stiffened by moun- 
 tain-chains and metamorphism, had become less yielding 
 than those of higher latitudes, the pressure from contraction 
 would have produced its oscillations in the latter rather 
 than the former. 
 
 Thus, the evolution of the features of the surface, even to 
 the terraces made along the river-valleys, as the era of Man 
 opened, may have taken place through one system of forces 
 originating in one single cause, the earth's contraction from 
 cooling. 
 
 CONCLUDING EEMAEKS. 
 
 Geology may seem to be audacious in its attempts to un- 
 veil the mysteries of creation. Yet what it reveals are 
 only some of the methods by which the Creator has per- 
 formed his will ; and many deeper mysteries it leaves un- 
 touched. 
 
 It brings to view a perfect and harmonious system of life, 
 but affords no explanation of the origin of life, or of its 
 species, or of any of nature's forces. 
 
 It accounts for the forms of continents ; but it tells nothing 
 as to the source of that arrangement of the wide and nar- 
 
CONCLUSION. . 337 
 
 row continents and wide and narrow oceans that was neces- 
 sary to the grand result (p. 11). 
 
 It teaches that strata were made in many successions as 
 the continents lay balancing near the water's level, some- 
 times just above the surface, sometimes a little below ; but 
 it does not explain how it happened that the amount of 
 water was of exactly the right quantity to fill the great 
 basin, and admit of oscillations of the land beneath or above 
 its surface by only small changes of level ; for if the water 
 had been a few hundred feet below the level it now has, 
 the continents would have remained mostly without their 
 marine strata, and the plan of progress would have proved 
 a failure ; or if as much above its present level, the land 
 through the earlier ages would have been sunk to depths 
 comparatively lifeless, with no less fatal results both to 
 the series of rocks'and the system of marine and terrestrial 
 life; and in the end there would have been broad and 
 narrow strips of dry land and archipelagos, in place of the 
 expanded Orient and Occident. 
 
 It may be said to have searched out the mode of develop- 
 ment of a world. Yet it can point to no physical cause of 
 that prophecy of Man which runs through the whole his- 
 tory ; which was uttered by the winds and waves at their 
 work over the sands, by the rocks in each movement of the 
 earth's crust, and by every living thing in the long succes- 
 sion, until Man appeared to make the mysterious announce- 
 ments intelligible. For the body of Man was not made 
 more completely for the service of the soul, than the earth, 
 in all its arrangements from beginning to end, for the spi- 
 ritual being that was to occupy it. In Man, the bones are 
 not merely the jointed framework of an animal, but a frame- 
 work shaped throughout with reference to that erect struc- 
 ture which befits and can best serve Man's spiritual nature. 
 The feet are not the clasping and climbing feet of a mon- 
 key ; they are so made as to give firmness to the tread and 
 
338 CONCLUSION. 
 
 dignity to the bearing of the being made in God's image. 
 The hands have that fashioning of the palm, fingers, and 
 thumb, and that delicacy of the sense of touch, which adapt 
 them not only to feed the mouth, but to contribute to the 
 wants of the soul and obey its promptings. The arms are 
 not for strength alone, for they are weaker than in many a 
 brute, but to give the greater power and expression to the 
 thoughts that issue from within. The face, with its express- 
 ive features, is formed so as to respond not solely to the 
 emotions of pleasure and pain, but to shades of sentiment 
 and interacting sympathies the most varied, high as heaven 
 and low as earth, aye, lower, in debased human nature. 
 And the whole being, body, limbs, and head, with eyes look- 
 ing not towards the earth, but beyond an infinite horizon, 
 is a majestic expression of the divine feature in Man, and of 
 the infinitude of his aspirations. 
 
 So with the earth, Man's world-body. Its rocks were so 
 arranged, in their formation, that they should best serve 
 Man's purposes. The strata were subjected to metamor- 
 phism, and so crystallized, that he might be provided with 
 the most perfect material for his art, his statues, temples, 
 and dwellings ; at the same time, they were filled with veins, 
 in order to supply him with gold and silver and other trea- 
 sures. The rocks were also made to enclose abundant beds 
 of coal and iron ore, that Man might have fuel for his 
 hearths and iron for his utensils and machinery. Moun- 
 tains were raised to temper hot climates, to diversify the 
 earth's productiveness, and, pre-eminently, to gather the 
 clouds into river-channels, thence to moisten the fields for 
 agriculture, afford facilities for travel, and supply the world 
 with springs and fountains. 
 
 The continents were clustered mostly in one hemisphere 
 to bring the nations into closer union ; and the two having 
 climates and resources the best for human progress the 
 northern Orient and Occident were separated by a narrow 
 
CONCLUSION. 339 
 
 ocean, that the great mountains might be on the remoter 
 borders of each, and all the declivities, plains, and rivers be 
 turned towards one common channel of intercourse. So, 
 also, the species of life, both of plants and animals, were 
 appointed to administer to Man's necessities, moral as well 
 as physical. 
 
 Besides these beneficent provisions, the forces and laws 
 of nature were particularly adapted to Man, and Man to 
 those laws, so that he should be able to take the oceans, 
 rivers, and winds into his service, and even the more subtle 
 agencies, heat, light, and electricity; and the adjustments 
 were made with such precision that the face of the earth is 
 actually fitted hardly less than his. own to respond to his 
 inner being : the mountains to his sense of the sublime, 
 the landscape, with its slopes, its trees, its flowers, to his 
 love of the beautiful, and the thousands of living species, 
 in their diversity, to his various emotions and sentiments. 
 The whole world, indeed, seems to have been made almost 
 a material manifestation, in multitudinous forms, of the ele- 
 ments of his own spiritual nature, that it might thereby give 
 wings to the soul in its heavenward aspirings. It may 
 therefore be said with truth that Man's spirit was con- 
 sidered in the ordering of the earth's structure as well as in 
 thatfof his own body. 
 
 It is hence obvious that the earth's history, which it is 
 the object of Geology to teach, is the true introduction to 
 human history. 
 
 It is also certain that science, whatever it may accom- 
 plish in the discovery of -causes or methods of progress, can 
 take no steps towards setting aside a Creator. Far from 
 such a result, it clearly proves that there has been not only 
 an omnipotent hand to create, and to sustain physical forces 
 in action, but an all-wise and beneficent Spirit to shape all 
 events towards a spiritual end. 
 
 Man may well feel exalted to find that he was the final 
 
340 CONCLUSION. 
 
 purpose when the word went forth in the beginning, LET 
 LIGHT BE. And he may thence derive direct personal assu- 
 rance that all this magnificent preparation is yet to have a 
 higher fulfilment in a future of spiritual life. This assu- 
 rance from nature may seem feeble. Yet it is at least suffi- 
 cient to strengthen faith in that Book of books in which the 
 promise of that life and " the way" are plainly set forth. 
 
APPENDIX. 
 
 A. Catalogue of American Localities of Fossils. 
 
 The following catalogue of American localities of fossils contains 
 only some of the more important, and is intended for the conve- 
 nience especially of the student-collector. 
 
 LOCALITIES OF FOSSILS. 
 
 Potsdam sandstone. Swan ton, Vt. ; Braintree, Mass. ; Keeseville 
 (at "High Bridge"), Alexandria, N.Y. ; Chiques Ridge, Pa.; Falls 
 of St. Croix, Osceola Mills, Trempaleau, Wisconsin ; Lansing, Iowa ; 
 St. Ann's, Isle Perrot, C.W. ; near Beauharnois on Lake St. Louis, 
 C.E. 
 
 Calciferous. Point Levis, Mingan Islands, Philipsburg, and near 
 Beauharnois, C.E. ; Grand Trunk Railway between Brockville and 
 Prescott, St. Ami's, Isle Perrot, C.W. ; Amsterdam, Port Plain, 
 Canajoharie, Chazy, Lafargeville, Ogdensburgh, N.Y. 
 
 Chazy limestone. Chazy, Galway, Westport, N.Y. ; Island of Mon- 
 treal, C.E., (1 to 3 miles north of "the Mountain.") 
 
 Bird? s-eye limestone. Amsterdam, Little Falls, Fort Plain, Adams, 
 Watertown, N.Y. 
 
 Black River limestone. Watertown, N.Y. ; Ottawa, C.W. ; Island 
 of Montreal, and near Quebec, C.E. 
 
 Trenton limestone. Adams, Watertown, Boonville, Turin, Jackson- 
 burgh, Little Falls, Lowville, Middleville, Fort Plain, Trenton 
 Falls, N.Y.; Pine Grove, Aaronsburg, Potter's Fort, Milligan's 
 Cove, Pa. ; Highgate Springs, Vt. ; Montmorency Falls and Beau- 
 port Quarries near Quebec, Island of Montreal (quarries N. of the 
 city), C.E. ; Ottawa, Belleville, Trenton (G. T. R. R., W. of Kings- 
 ton), C.W.; Copper Bay, Mich.; Elkader Mills, Turkey River, 
 Dubuque, Iowa; Falls of St. Anthony, St. Paul, Mineral Point, 
 Cassville, Beloit, Quimby's Mills near Benton, Wis. ; Warren, 
 Illinois. 
 
342 APPENDIX. 
 
 Utica slate. Turin, Martin sburgh, Lorraine, Worth, Utica, Cold 
 Spring, Oxtungo and Osquago Creeks near Fort Plain, Mohawk, 
 House's Point, N.Y. ; Kideau River along R. R. at Ottawa, bed of 
 river two miles above, C.W. 
 
 Hudson River group. Pulaski, Rome, Lorraine, and Boonville, 
 N.Y. ; Penn's Valley, Milligan's Cove, Pa. ; Oxford, Cincinnati, 0. ; 
 Madison, Ind. ; Anticosti, opposite Three Rivers, C.E. ; Weston on 
 the Humber River, nine miles W. of Toronto, C.W. ; Little Mako- 
 queta River, Iowa ; Savannah, Green Bay, Wis. ; Scales Mound, 
 111. ; Drummond's Island, Mich'. 
 
 Medina sandstone. Lock port, Lewiston, Medina, Rochester, N.Y. ; 
 Long Narrows below Lewistown, Pa. 
 
 Clinton group. Lewiston, Lockport, Reynolds' Basin, Brockport, 
 Rochester, Wolcott, New Hartford, N.Y. ; Thorold on Welland 
 Canal, Hamilton, Ancaster, C.W. 
 
 Niagara. Lewiston, Lockport, Rochester, Wolcott, N.Y. ; Tho- 
 rold, Hamilton, Ancaster, C.W. ; Anticosti, C.E. ; Arisaig, Nova 
 Scotia ; Racine, Waukesha, Wis. ; Marblehead on Drummond's 
 Island, Michigan. ( Coralline limestone. Schoharie, N.Y.) 
 
 Onondaga Salt Group. Buffalo, Williams ville, Waterville, Jeru- 
 salem Hill (Herkimer co.), N.Y. 
 
 Leclaire limestone. Leclaire, 111. * 
 
 " Gait" or "Guelph" formation. Gait, Guelph (G. T. R. R.), C.W. 
 
 Lower Helderberg limestones. Dry Hill, Jerusalem Hill (Herkimer 
 co.), Sharon, East Cobleskill, Judd's Falls, Cherry Valley, Carlisle, 
 Schoharie, Clarksville, Athens, N.Y. ; Gaspe, C.E. 
 
 Oriskany sandstone. Oriskany, Vienna, Carlisle, Schoharie, Cats- 
 kill Mountains, N.Y. ; Cumberland, Md. ; Moorestown and Franks- 
 town, Pa. 
 
 Cauda-Gatti Grit. Schoharie (Fucoides Cauda-Galli), N.Y. 
 
 Schoharie Grit. Schoharie, Cherry Valley, N.Y. 
 
 Upper Helderberg limestones. Black Rock, Buffalo, Williamsville, 
 Lancaster, Clarence Hollow, Stafford, Le Roy, Caledonia, Mendon, 
 Auburn, Onondaga, Cassville, Babcock's Hill, Schoharie, Cherry 
 Valley, Clarksville, N.Y. ; Port Colborne, and near Cayuga, C.W. ; 
 Columbus, Delaware, Sandusky, 0. ; Mackinac, Little Traverse Bay, 
 Dundee, Monguagon, Mich. 
 
 Marcellus shales. Lake Erie shore, ten miles S. of Buffalo, Lancas- 
 ter, Alden, Avon, Leroy, Marcellus, Manlius, Cherry Valley, N.Y. 
 
APPENDIX. 343 
 
 Hamilton group. Lake Erie shore, Eighteen Mile Creek, Ham- 
 burgh, Alden, Darien, York, Moscow, Bloomfield, Bristol, Seneca 
 Lake, Cayuga Lake, and Skaneateles Lake, Pompey, Cazenovia, 
 Delphi, Bridgewater, Klchland, Cherry Valley, Seward, Westford, 
 Milford, Portlandville, N.Y. ; Widden Station (G. T. E. R.), near 
 Port Sarnia, C.W. ; New Buffalo, Independence, Iowa ; Rock 
 Island, III. ; Thunder Bay, Little Traverse Bay, Mich. ; Nictaux, 
 Bear River, Moose River, Nova Scotia. 
 
 Genesee slate. Banks of Seneca and Cayuga Lakes, Lodi Falls, 
 Mount Morris, two miles S. of Big Stream Point, Yates co., N.Y. 
 
 Portage group. Eighteen Mile Creek, Lake Erie shore, Chautau- 
 qua Lake, Genesee River at Portage, Flint Creek, Cashaqua Creek, 
 Nunda, Seneca and Cayuga Lakes, N.Y. 
 
 Chemung group. Rockville, Philipsburgh, Jasper, Greene, Che- 
 mung Narrows, Troopsville, Elmira, Ithaca, Waverly, Hector, En- 
 field, N.Y. ; Gaspe, C.E. 
 
 Cats kill group. Fossils rare. Richmond's quarry above Mt. Upton 
 on the Unadilla, Oneonta, Oxford, Steuben co. south of the Canis- 
 teo, N.Y. ; Blossburg, Pa. ; Pomp ton, Old Boonton, Pluckamin, 
 N.J. 
 
 Subcarboniferous. Burlington, Keokuk, Iowa ; Quincy, Warsaw, 
 Alton, Kaskaskia, Chester, 111. ; Bloomington, Spergen Hill, Ind. ; 
 Hannibal, St. Genevieve, St. Louis, Mo. ; Willow Creek, Battle 
 Creek, Holland, Grand Rapids, Mich. ; Mauch Chunk, Pa. ; Red 
 Sulphur Springs, Pittsburg Landing, Tenn. ; Big Bear and Little 
 Bear Creeks, Big Crippled Deer Creek, Miss. ; Clarksville, Hunts- 
 ville, Ala. ; Windsor, Horton, Nova Scotia. 
 
 Carboniferous. South Joggins, Pictou, Sydney, Nova Scotia ; 
 Wilkesbarre, Shamokin, Tamaqua, Pottsville, Minersville, Tremont, 
 Greensburg, Carbondale, Port Carbon, Lehigh, Trevorton, Johns- 
 town, Pittsburg, Pa. ; Pomeroy, Marietta, Zanesville, Cuyahoga 
 Falls, Athens, Ohio ; Charlestown, Clarksburg, Kanawha Salines, 
 Wheeling, Va. ; Saline Company's mines, Gallatin co., Terre Haute, 
 Morris, Springfield, 111. : Bell's, Casey's, and Union Mines, Critten- 
 den co. ; Hawesville and Lewisport, Hancock co. ; Breckinridge, 
 Giger's Hill, Mulford's Mines, and Thompson's Mine, Union co. ; 
 Providence and Madisonville, Hopkins co. ; Bonharbour, Daviess 
 co., Ky. : Muscatine, Alpine Dam, Iowa ; Leavenworth, Indian 
 Creek, Grasshopper Creek, Juniata, Manhattan, Kansas. 
 
 30 
 
344 APPENDIX. 
 
 Triassic. Southbury, Middlefield, Portland, Conn. ; Turner's 
 Falls, Sunderland, Mass. ; Phcenixville, Pa. ; Kichmond, Va. ; 
 Deep River and Dan River coal-fields, N.C. 
 
 Cretaceous. Upper Freehold, Middletown, Marlboro', Blue Ball, 
 Deal, Squankuin, Shark River, Monmouth co. ; Pemberton, Vin- 
 centon, Burlington co. ; Blackwoodtown, Camden co. ; Mullica Hill, 
 Gloucester co. ; Woodstown, Mannington, Salem co. ; New Egypt, 
 Ocean co., N. J. : Warren's Mill, Itawamba co. ; Tishomingo Creek, 
 R. R. cuts, Hare's Mill, Carrollsville, Tishomingo co. ; Plymouth 
 Bluff, Lowndes co. ; Chawalla Station (M. & C. R. R.), Ripley, Tip- 
 pah co. ; Noxubee, Macon, Noxubee co. ; Kemper, Pontotoc and 
 Chickasaw counties, Miss. : Tuscaloosa, Ala. : Fox Hills, Sage 
 Creek, Long Lake, Great Bend, Cheyenne River, etc., Nebraska. 
 
 Eocene. Everywhere in Tippah co. ; Yockeney River, New 
 Prospect P. 0., Winston co. ; Marion, Lauderdale co. ; Enterprise 
 Clarke co. ; Jackson ; Satartia, Yazoo co. ; Homewood, Scott co. 
 Chickasawhay River, Clarke co. ; Winchester, Red Bluff Station 
 Wayne co. ; Vicksburg, Amsterdam, Brownsville, Warren co. 
 Brandon, Byram Station, Rankin co. ; Paulding, Jasper co., Miss. 
 Claiborne, Monroe co. ; St. Stephen's, Washington co., Ala. : Charles- 
 ton, S.C. ; Tampa Bay, Florida ; Fort Washington, Fort Marlbo- 
 rough, Piscataway, Md. ; Marlbourne, Va. ; Brandon, Vt. ; Canada 
 de las Uvas, Cal. 
 
 Miocene. Gay Head, Martha's Vineyard, Mass. ; Shiloh, Jericho, 
 Cumberland co., N.J. ; St. Mary's, Easton, Md. ; Yorktown, Suffolk, 
 Smithfield, Richmond, Petersburg, Va. ; Astoria, Willamette River, 
 Oregon ; San Pablo Bay, Ocoya Creek, San Diego, Monterey, San 
 Joaquin and Tulare Valleys, Cal. ; White River, Upper Missouri 
 Region. 
 
 Pliocene. Ashley and Santee Rivers, S.C. ; Platte and Niobrara 
 Rivers, Upper Missouri. 
 
 B. Geological Implements, Specimens, etc. 
 
 1. Implements. The student requires for his geological excur- 
 sions and research the following implements : 
 
 (1.) A hammer of the form in fig. 373. The face should be flat, 
 and nearly square, with its edges sharp instead of rounded. The 
 socket for the handle should be large, that the handle may be 
 
APPENDIX. 
 
 345 
 
 strong. The hammer, for ordinary excursions, should weigh 1 
 pounds exclusive of the handle ; the handle should be about 12 
 inches long. Another is required for trimming specimens, weigh- 
 ing half a pound. 
 
 Fig. 373. 
 
 Fig. 374. 
 
 (2.) A hammer in the form of a small pick, like fig. 374, for pick- 
 ing open the layers of slaty rocks, etc. It should be 7 or 8 inches 
 long, and terminate above in a chisel-like edge transverse to the 
 handle. The length of handle may be 13 or 14 inches. 
 
 (3.) A steel chisel, 6 inches long, 1 inch wide at top, and tapering 
 to a narrow edge, or wedge-shaped. Also, another half of these 
 dimensions. 
 
 (4.) A clinometer, with magnetic needle attached. See page 40. The 
 best kind is a pocket instrument in the form of a watch, about 2 
 inches in diameter. 
 
 (5.) A small magnet. A magnetized blade of a pocket-knife is a 
 good substitute. 
 
 (6.) A measuring-tape feet long. The field geologist should 
 know accurately the measurements of his own body, his height, 
 length of limbs, step or pace, that he may use himself, whenever 
 needed, as a measuring-rod. 
 
 (7.) In many cases, a pick, a crow-bar, a sledge-hammer of 4 to 8 
 pounds' weight, and the means of blasting, are necessary. 
 
 (8.) A strong sack-coat, with very large and stoutly made side- 
 pockets. 
 
 (9.) Besides the above, a barometer and surveyor's instruments are 
 occasionally required. Of the latter, a hand-level is a very desirable 
 instrument for determining small elevations by levelling. It is a 
 simple brass tube, with cross-hairs, bubble and mirror. 
 
346 APPENDIX. 
 
 2. Specimens, Specimens for illustrating the kinds of rocks 
 should be carefully trimmed by chipping to a uniform size, pre- 
 viously determined upon : 3 inches by 4 across, and 1 inch through, 
 is the size commonly adopted. In the best collections of rocks, the 
 angles are squared and the edges made straight with great preci- 
 sion. They should have a fresh surface of fracture, with no bruises 
 by the hammer. It is often well to leave one side in its natural 
 weathered state, to show the effects of weathering. 
 
 Specimens of fossils will, of course, vary in size with the nature of 
 the fossil. When possible, the fossil should be separated from the 
 rock ; but this must be done with precaution, lest it be broken in 
 the process, and should not be attempted unless the chances are 
 strongly in favor of securing the specimen entire. The skilful use 
 of a small chisel and hammer will often expose to view nearly all 
 of a fossil when it is not best wholly to detach it. When the fossils 
 in a limestone are silicified (a fact easily proved by their scratching 
 glass readily and their undergoing no change in heated acid), they 
 may be cleaned by putting them into an acid, and also applying 
 heat very gently, if effervescence does not take place without it. 
 The best acid is chlorohydric (muriatic) diluted one-half with 
 water. 
 
 Collections both of rocks and fossils should always be made from 
 rocks in place, and not from stray boulders of uncertain locality. 
 
 3. Packing. For packing, each specimen should be enveloped 
 separately in two or three thicknesses of strong wrapping-paper. 
 This is best done by cutting the paper of such a size that when 
 folded around the specimen the ends will project two inches (more 
 or less, according to the size of the specimen) ; after folding the 
 paper around it, turn in the projecting ends (as the end of the 
 finger of a glove may be turned in), and the envelop will need no 
 other securing. Pack in a strong box, pressing each specimen, 
 after thus enveloping it, firmly into its place, crowding wads of 
 paper between them wherever possible, and make the box abso- 
 lutely full to the very top (by packing-material if the specimens do 
 not suffice), so that no amount of rough usage by wagon or cars on 
 a journey of a thousand miles would cause the least movement 
 inside. 
 
APPENDIX. 347 
 
 4. Labelling. A label should be put inside of each envelop, sepa- 
 vated from the specimen by a thickness or more of the paper. The 
 label should give the precise locality of the specimen, and the par- 
 ticular stratum from which taken, if there is a series of strata at the 
 place ; it should also have a number on it corresponding to a num- 
 ber in a note-book, where fuller notes of each are kept, together 
 with the details of stratification, dip, and strike, sections, plans, 
 changes or variations in the rocks, and all geological observations 
 that may be made in the region. A specimen of rock or fossil of 
 unknown or uncertain locality is of very little value. 
 
 5. Note-Book. The note-book should have a stiff leather cover, 
 and be made of rather thick smooth writing-paper, good for 
 sketching as well as for writing. Five inches by three and a half 
 is a convenient size. A kind made of prepared paper, and pro- 
 vided with a zinc-pointed pencil, is often sold for the purpose, and 
 is excellent until it gets perchance a fall into the water, when the 
 notes that may have been carefully made will be pretty surely 
 obliterated. If the geologist is a draftsman, he may also need a 
 portfolio for carrying larger paper ; but the small note-book will, in 
 general, answer every purpose. 
 
 30* 
 
INDEX. 
 
 NOTE. The asterisk after the number of a page indicates that the subject referred to is 
 illustrated by a figure. 
 
 Acalephs, 58.* 
 
 Apennines, origin of, 203, 218. 
 
 Bathygnathus borealis, 170.* 
 
 Acanthoteuthis, 177.* 
 
 Appalachian Coal area, 117. 
 
 Beach-tormations, 226, 287, 289. 
 
 Acephals, 56* 
 
 revolution, 155. 
 
 nuts, fossil, 210.* 
 
 Acrodus minimus, 52.* 
 
 Appalachians, formation of, 
 
 structure, 31.* 
 
 nobilis, 52.* 
 Acrogens, 60. 
 
 155, 246, 247. 
 folded rocks of, 41,* 156.* 
 
 Beaver, tormer geographical 
 range of, 241. 
 
 Carboniferous, 126. 
 
 thickness of formations 
 
 Belemnitella mucronata, 193.* 
 
 Devonian, 108. 
 
 of, 80, 86, 92, 102. 
 
 Belemnites, 177,* 193.* 
 
 Actinia, 57* 
 
 Araucarise, 62. 
 
 Bernese Alps, 292. 
 
 Actinocrinus proboscidialis, 
 
 Archseoniscus Brodiei, 178.* 
 
 Bilin, infusorial bed of, ^lO. 
 
 131.* 
 
 Archimedes reversa, 131.* 
 
 Birds, 50. 
 
 JEpiornis, extinction of, 241. 
 
 Arctic climate in Jurassic, 187. 
 
 first of. 170. 
 
 Ages in Geology, 63. 
 
 climate in Carboniferous, 
 
 of Connecticut valley, 172.* 
 
 Age, Carboniferous, 116. 
 
 149. 
 
 of Solenhofen, 183, 201. 
 
 Devonian, 104. 
 
 climate in Cenozoic, 234. 
 
 Tertiary, 213. 
 
 Mammalian, 205. 
 
 coal area, 119. 
 
 Bituminous coal, 18, 123. 
 
 of Coal Plants, 116. 
 
 Argillaceous schist, 24. 
 
 Bivalves, 56.* 
 
 of Fishes, 104. 
 
 Argillite, 24. 
 
 Black-river limestone, 86. 
 
 of Man, 236. 
 
 Artesian wells, 281, 300. 
 
 Black slate, of Devonian, 105. 
 
 of Mollusks, 78. 
 
 Articulates, 49, 53.* 
 
 Blattina venusta, 132.* 
 
 Reptilian, 162. 
 
 first of terrestrial, 107. 
 
 Bois Glacier. 292. 
 
 Silurian, 78. 
 
 Asaphus gigas, 89.* 
 
 Bore, 285. 
 
 Albite, 15. 
 
 Ascidians, 57. 
 
 Boulders, 220, 27$. 
 
 Algse, 60. 
 
 Astarte Conradi, 211.* 
 
 transported by glaciers, 
 
 Alluvial deposits, 224, 279. 
 
 Athyris subtilita, 131 * 
 
 294; 
 
 Alps, elevation of, 203, 218. 
 
 Atmosphere,agency of, in caus- 
 
 Brachiopods, 56 * 
 
 America, N., Geography of. 
 
 ing geological changes, 
 
 Carboniferous, 131.* 
 
 See GEOGRAPHY. 
 
 271. 
 
 Devonian, 111.* 
 
 Ammonites, 175.* 
 
 Atolls, 268 * 
 
 Primordial, 81.* 
 
 Humphreysianus, 175.* 
 
 Atrypa aspera, 112.* 
 
 Silurian, 88,* 97* 
 
 Jason, 175.* 
 
 Aulopora cornuta, 111.* 
 
 Brakes, 60. 
 
 Placenta, 193.* 
 of Mesozoic, 200. 
 
 Australia, basaltic columns of, 
 311* 
 
 Brandon fossil fruits, 209* 
 Breccia, 22. 
 
 tornatus, 176.* 
 
 Australian character of vege- 
 
 Bryozoans, 57.* 
 
 Amphibians, 50. 
 
 tation in Tertiary Eu- 
 
 Carboniferous, 130.* 
 
 Amphipods, 54.* 
 Amphitherium, 183.* 
 
 rope, 219. 
 Marsupials of, in Post- 
 
 Devonian, 111.* 
 Silurian, 81,* 88,* 98.* 
 
 Amygdaloid, 311. 
 
 tertiary, 233. 
 
 Buffalo, former geographical 
 
 Anatifa, 54.* 
 
 Avicula emacerata, 97.* 
 
 range of, 241. 
 
 Andalusite, 17 * 
 
 Trentonensis, 88.* 
 
 Buhrstone, Tertiary, 208. 
 
 Andes, origin of, 203, 219. 
 
 Azoic Time, or Age, 72. 
 
 Bunter sandstein, 168. 
 
 Angiosperms, 62. 
 
 continent, map of, 73. 
 
 Buprestis, 178.* 
 
 first of, 188, 190,* 202. 
 
 continent, observations 
 
 
 in Tertiary, 209* 
 
 on, 334. 
 
 Calamites, 108, 128 * 
 
 Animal kingdom, 47, 48. 
 
 rocks, 73. 
 
 in Triassic, 167. 
 
 Anisopus, tracks of, 171.* 
 
 
 Calamopsis Danae, 210.* 
 
 Anogens, 60. 
 
 Baculites ovatus, 193.* 
 
 Calcareous rocks, 21, 24. 
 
 Anoplothere, 214. 
 
 Bad Lands, fossils of, 215. 
 
 Calcite, 18.* 
 
 Anthracite, 18, 123. 
 
 Bagshot beds, 209. 
 
 Callista Sayana, 212* 
 
 origin of, 156, 313. 
 Anthracopalaemon, 132. 
 
 Bala formation, 87. 
 Basalt, 26, 311. 
 
 Dalymene Blumenbachii, 89.* 
 Cambrian, 80. 
 
 Anticlinal, 41.* 
 
 Basaltic columns, 35,* 311.* 
 
 Camel, Tertiary American, 21& 
 
350 
 
 INDEX. 
 
 Cafions, 276* 
 Caradoc sandstone, 87. 
 Carbon, 18. 
 
 Carbonate of lime, 18. 
 Carbonic acid, 18. 
 Carboniferous Age, 116. 
 
 period, 116, 121. 
 Carcharodon angustidens, 52.* 
 
 teeth of, 212. 
 Carnivores, first of, 213. 
 
 characteristic of Post-ter- 
 tiary, in the Orient, 231. 
 Carpathians, origin of, 218. 
 Caryocrinus ornatus, 97.* 
 Catastrophes, origin of, 332. 
 Catopterus gracilis, 170.* 
 Catskill period, 104. 
 Cauda-galli grit, 10 L 
 Caves of Europe, Post-tertiary, 
 
 230. 
 Cenozoic time, 205. 
 
 time, general observations 
 
 on, 234. 
 
 Cephalaspis, 113.* 
 Cephalates, 55 * 
 Cephalopods, 55.* 
 
 of Mesozoic, 200. 
 Cestracionts, 52,* 114, 178. 
 Chaetetes Lycoperdon, 88.* 
 Chain-coral, 97.* 
 Chalk, 189, 197. 
 
 formation of, 266. 
 Champlain epoch, 219, 224. 
 Charcoal, 18. 
 Chazy limestone, 86. 
 Cheirotherium footprints, 
 
 179* 
 
 Chemung period, 104. 
 Chisel, geological, 344. 
 Chlorite schist, 23. 
 Chonetes mesoloba, 131.* 
 
 setigera, 112* 
 Cidaris Blumenbachii, 173* 
 Cinder-cones, 304. 
 Cinders, 303. 
 
 Cinnamomum, Tertiary, 210.* 
 Claiborne epoch, 206. 
 Clathropteris rectiusculus 
 
 168* 
 Clay, 20. 
 Cleavage, slaty, 36.* 
 
 slaty, origin of, 323. 
 Cliifs, wear of, 283* 
 Climate, Carboniferous, 138. 
 
 Cretaceous, 197. 
 
 Jurassic, 187. 
 
 Paleozoic, 149. 
 
 Post-tertiary, 234. 
 
 Tertiary, 219. 
 
 Clinkstone. See PHONOLITE. 
 Clinton group, 94. 
 Coal areas of Britain and Eu 
 rope, 119* 
 
 areas of N.America, 117 . : 
 
 beds, characters of, 123. 
 
 beds of Triassic. 164. 
 
 Coal, deprived of bitumen, 
 156. 
 
 formation of, 135. 
 
 formation, rocks of, 122. 
 
 kinds of, 18, 123. 
 
 plants of Richmond, 169.* 
 
 plants of the Carbonifer- 
 ous, 126.* 
 3occosteus, 113. 
 >oin-conglomerate, 239.* 
 Colorado, canon of, 276.* 
 Columnaria alveolata, 88.* 
 Comprehensive types, 168, 253. 
 Conchifers, 56.* 
 /oncretions, 33.* 
 /onformable strata, 43.* 
 Conglomerate, 22. 
 Conifers, 61, 109. 
 
 in Triassic, 167. 
 
 of Carboniferous, 128. 
 
 Connecticut River sandstone 
 
 and footprints, 164. 
 
 trap rocks, 186. 
 Continents, basin-like shape 
 of, 9.* 
 
 origin of, 329. 
 
 relations of, 6, 7, 8, 10. 
 Contraction a cause of change 
 
 of level, 320. 
 Coprolites, 183. 
 Coral islands, 268* 
 
 reef of the Devonian, 105. 
 
 reefs, 266* 
 Corals, formation of, 58. 
 
 fossil, 88 * 97,* 111,* 131* 
 
 173* 
 
 Coralline crag, 209. 
 Corniferous limestone, 105. 
 
 period, 104. 
 
 Cosmogony, 77, 93, 260. 
 Cotopaxi, volcano of, 301.* 
 Crabs, 53.* 
 
 Crassatella alta, 211 * 
 Crater, 302. 
 Creations of species, 92, 116, 
 
 152, 257. 
 Crepidula costata, 212.* 
 Cretaceous period, 163, 188. 
 
 America, map of, 196. 
 Crevasses, 292. 
 Cricodus, 51* 
 Crinoidal limestone, Subcar- 
 
 boniferous, 121. 
 Crinoids, 58* 
 
 Jurassic, 173* 
 
 Primordial, 83 * 
 
 Silurian, 88,* 97* 
 
 Subcarboniferous, 130.* 
 Crocodiles, 195. 
 Crocodilus, first of, 202. 
 Crustaceans, 53.* 
 Cryptogams, 60. 
 Crystalline rocks, 20. 
 Crystallization in metamor 
 phism, 312. 
 
 of Azoic rocks, 75. 
 
 Crystallizations during the 
 Appalachian revolution, 
 156. 
 
 Ctenacanthus major, 133.* 
 
 Ctenoids, 50* 
 
 Currents, oceanic, 285, 286. 
 
 "lyathophylloid corals, 88,* 98,* 
 
 Cyathophyllum rugosum, 
 
 111* 
 Cycads, 61. 
 
 Triassic and Jurassic, 167, 
 Cycloids, 50.* 
 3yclonema cancellata, 97.* 
 Cyclopteris linnseifolia, 168.* 
 ystideans, 57,* 98. 
 
 Decapods, 53.* 
 
 Deer, fossil, 215, 216. 
 
 Delta of Mississippi, 280* 
 
 Deltas, 279. 
 
 Denudation, 42,* 273, 283, 295, 
 298. 
 
 Depth, zones in, 332. 
 
 Desmids, 61,* 109* 
 
 Detritus, 279, 281. 
 
 Development- theory, objec- 
 tions to, 115, 257. 
 
 Devonian age, 104. 
 
 hornstone, microscopic or- 
 ganisms in, 109.* 
 
 Diamond, 18. 
 
 Diatoms, 61.* 
 
 formation of deposits by, 
 
 263, 265. 
 Tertiary, 210. 
 
 Dicotyledons, 62. 
 
 Dikes, 30,* 311. 
 
 Dinornis, extinction of, 241. 
 
 Dinothere, 216* 
 
 Diorite, 26. 
 
 Dip, 39.* 
 
 Dipterus, 113.* 
 
 Dislocated strata, 38.* 
 
 Disturbances closing Paleo- 
 zoic, 154, 161. 
 
 Dodo, extinction of, 241. 
 
 Dolerite, 26, 311. 
 
 Dolomite, 19, 25. 
 
 Drift, 220. 
 
 sands, 32,* 271. 
 scratches, 221.* 
 
 Dromatherium sylvestre, 172.* 
 
 Dudley limestone, 96. 
 
 Dunes, 272. 
 
 Dynamical Geology, 262. 
 
 Eagre, 285. 
 
 Earth, size and form of, 5. 
 general features of surface 
 
 of, 5. 
 
 relation to Man, 336. 
 Earth's crust, general struc- 
 ture of, 1. 
 
 features, origin of, 326, 328. 
 Earthquakes, origin of, 324. 
 
INDEX. 
 
 351 
 
 Ebb-and-flow structure, 31, 80, 
 
 289. 
 Echini, 57.* 
 
 Mesozoic, 174* 
 Echinoderms, 57.* 
 Edentates, Post-tertiary, 232.* 
 Elephants, Post-tertiary, 231, 
 232. 
 
 Tertiary, 216. 
 Elephas primigenius, 231. 
 Elevation of Alps, 203, 218. 
 
 of Appalachians, 155. 
 
 of Apennines, 203, 218. 
 
 of coast of Sweden, 242. 
 
 of Green Mountains, 91. 
 
 of Rocky Mountains, 203, 
 217. 
 
 of western South Ame- 
 rica, 242. 
 Elevations, causes of, 318. 
 
 after Cretaceous, 203. 
 
 after Paleozoic, 154. 
 
 in Age of Man, 241. 
 Emery, 15. 
 
 Emmons, fossil mammal of 
 Triassic described by, 
 172. 
 
 Enaliosaurs, 135,* 180.* 
 Encrinua liliiformis, 57,* 173.* 
 Endogens, 62. 
 
 England in the Reptilian age, 
 201. 
 
 geological map of, 120.* 
 Entomostracans, 53.* 
 Eocene, 206. 
 
 era in the Orient, 218. 
 Eosaurus Acadianus, 134.* 
 Equiseta, 60, 108, 128. 
 Equivalent strata, 44. 
 Erosion by rivers, 273. 
 
 over continents, 298. 
 Eruptions of volcanoes, 306, 308. 
 
 non- volcanic, 310. 
 Estheria ovata, 169.* 
 Estuary formations, 279. 
 Eurypterus remipes, 98.* 
 Exogyra costata, 192.* 
 Extermination of species, 93, 
 150, 200, 202, 256. 
 
 number of species of plants 
 and animals lost by, 251. 
 
 of species, methods of, 256. 
 332. 
 
 Fasciolaria bticcinoides, 193.* 
 Faults, 41,* 158.* 
 Favosites Goldfussi, 111.* 
 
 Niagarensis, 97. 
 Feldspar, 15. 
 Ferns, 60. 
 
 of the Coal era, 126.* 
 Fingal's Cave, 301. 
 Fiords, 220. 
 Fishes, 50* 
 
 Age of, 104. 
 
 Carboniferous, 133.* 
 
 Fishes, first of Ganoid and Sela- 
 chians, or Devonian, 111.* 
 
 first Telioet, 188, 194 * 
 
 Mesozoic 170,* 178 * 194 * 
 Fish-spines, 113,* 133.* 
 Flags, 22. 
 
 Flint, 14, 189, 192, 197, 266. 
 Flint arrow-heads, 239. 
 Fluvio-marine formations, 288. 
 Folded rocks, 41,* 74, 156,* 320. 
 Footprints. See TRACKS. 
 Foraminifera, 59.* 
 Formation, 28. 
 Fossiliferous limestone, 24. 
 Fossils, use of, in determining 
 the equivalency of 
 strata, 3, 45. 
 
 list of localities of, 341. 
 
 number of species of, 252. 
 Fragmental rocks, 20, 22. 
 Freestone of Portland, Ct., 164. 
 Fresh waters, action of, 273. 
 Fusus Newberryi, 193.* 
 
 Ganoids, 51* 
 
 Devonian, 111.* 
 
 Triassic, 170* 
 Sarnet, 16.* 
 Jrasteropods, 56.* 
 Grenera, long-lived, 151. 
 Genesee shale, 105. 
 Genesis, 77, 93, 260. 
 Geoclinal, 42. 
 
 Geography, progress in North 
 America, 146, 245, 333. 
 
 American, in Azoic, 76.* 
 
 in Carboniferous, 139. 
 
 in Cretaceous, 196.* 
 
 in Devonian, 115. 
 
 in Mesozoic, 198. . 
 
 in Post-tertiary, 226, 228. 
 
 in Silurian, 90, 99. 
 
 in Tertiary, 216.* 
 
 in Triassic, 184. 
 Geysers, 309. 
 Giants' Causeway, 311. 
 Glacial epoch, 219, 220. 
 Glacier, great, of Switzerland, 
 223, 293* 
 
 regions, 295. 
 
 scratches, 221.* 
 
 theory of the drift, 223. 
 Glaciers, 231. 
 
 Glen Roy, benches of, 229. 
 Glyptodon, 232.* 
 Gneiss, 23. 
 Goniatites, first of, 110. 
 
 last of, in Triassic, 175, 200. 
 
 Marcellensis, 111.* 
 Grammysia Hamiltonensis, 
 
 112* 
 
 Granite, 23, 25. 
 Graphite, 18, 76. 
 Graptolites, 82.* 
 Great Britain in the Reptilian 
 age, 201. 
 
 Greenland, glaciers of, 295. 
 Green Mountains, emergence 
 
 of, 91. 
 Green-sand, 189. 
 Grit, 22. 
 
 Ground-pine, 60. 
 Gryphgea, species of, 174,* 192 * 
 Guadaloupe, human skeleton 
 
 of, 240* 
 Gulf of Mexico, progress of, 217. 
 Gymnosperms, 61. 
 Gypsiferous formation, 165. 
 Gypsum, 95, 125, 165. 
 yrodus umbilicus, 51.* 
 
 Halysites catenulatus, 97.* 
 Hamilton formation, 105. 
 
 period, 104. 
 
 Hammer, geological, 344.* 
 Harmony in the life of an age, 
 
 254. 
 
 Hawaii, volcanoes of, 301,* 304* 
 Headon group, 209. 
 Heat, 299. 
 
 evidence of internal, 299. 
 Height of Aconcagua peak, 302. 
 
 of Cotopaxi, 301. 
 
 of Illimani, 302. 
 
 of Sorata, 302. 
 Hempstead beds, 209. 
 Herbivores, first of, 213. 
 Herculaneum, 309. 
 Heterocercal, 51.* 
 Himalayas, origin of, 203, 218. 
 Hitchcock, E., tracks'described 
 
 by, 170* 
 
 Holoptychius, 113.* 
 Holyoke, 311. 
 Homalonotus, 97.* 
 Homocercal, 51. 
 
 rocks, 23. 
 Hornblende, 16. 
 Hornstone, 105. 
 
 microscopic remains in, 
 
 109.* 
 
 Horse, fossil, 215, 216. 
 Hudson period, 85. 
 Hysena spelsea, 230. 
 Hybodus, species of, 52.* 
 Hydroid Acalephs, 58,* 82* 
 
 Ice of lakes and rivers, 291. 
 
 glacier, 291. 
 Icebergs, 223, 286, 296. 
 Iceberg theory of the drift, 223. 
 Ichthyosaurus, 180,* 195. 
 Igneous rocks, 21, 25. 
 
 ejections of Lake Superior 
 region, 91. 
 
 ejections, Triassic, 165. 
 Iguanodon, 181, 195. 
 Illinois coal area, 117. 
 Infusorial beds, Tertiary, 210. 
 Ink-bag, fossil, 176.* 
 Inoceramus problematicus, 
 192* 
 
352 
 
 INDEX. 
 
 Insectivores, Jurassic, 184. 
 
 Life, general laws of progress 
 
 Insects, 53. 
 
 of, 250. 
 
 first of, 107. 
 
 of Age of man, 238. 
 
 Carboniferous, 133.* 
 
 Life. See SPECIES. 
 
 Triassic, 169.* 
 
 Lignite, 18, 219. 
 
 Irish Elk, 230. 
 
 Limestone, 24, 25. 
 
 C>n ore beds of Azoic, 74.* 
 mountains of Missouri, 74. 
 pods, 54.* 
 
 formation of, 265, 269, 297. 
 Limestones of Mississippi 
 valley, 143. 
 
 Isotelus gigas, 89.* 
 Itacolumite, 24. 
 
 Lingula flags, 80. 
 Lingulae, 81.* 
 
 
 Liriodendrom Meekii, 191.* 
 
 Jackson epoch, 206. 
 
 Lithological Geology, 13. 
 
 Joints in rocks, 35.* 
 
 Lithostrotion Canadense, 131.* 
 
 origin of, 324. 
 Jurassic period, 163. 
 
 Llandeilo flags, 87. 
 Llandovery beds, 96. 
 Localities of fossils, list of, 
 
 Keuper, 166. 
 
 341. 
 
 Kilauea, 304.* 
 
 London clay, 209. 
 
 Kingsmill Islands, 269. 
 
 Lorraine shale, 87. 
 
 
 Lower Helderberg, 95. 
 
 Labradorite, 16. 
 Labyrinthodonts, 179.* 
 
 Ludlow group, 96. 
 
 Lacustrine deposits, 224.* 1 Machgerodus, 230. 
 
 Lake Champlain in Post-ter- i Madagascar, ^piornis, of, 241. 
 tiary, 226, 227. JMagnesian limestone, 19, 25. 
 
 Memphremagog, Devo- 
 
 Mammals, 50. 
 
 nian coral reef of, 105. 
 
 Age of, 205. 
 
 Lakes, origin of great, 148, 247. 
 
 first of, 170. 
 
 Lamellibranchs, 56.* 
 
 Jurassic, 183 * 201. 
 
 Laminated structure, 21, 31.* 
 
 Mesozoic, 201. 
 
 Lamna elegans, 52,* 213. 
 
 Post-tertiary, 230.* 
 
 Land-slides, 282. 
 
 Tertiary, 213.* 
 
 Lava, 26, 303. 
 
 Triassic, 172.* 
 
 Lava-cones, 304. 
 
 Man, Age of, 236. 
 
 Layer, 28. 
 
 characteristics of, 236. 
 
 Lecanocrinus elegans, 89.* 
 
 fossil, of Guadaloupe, 239.* 
 
 Leguminosites, 191.* 
 
 place of origin of, 240. 
 
 Leidy, J., fossil animals de- 
 scribed by, 170,* 215. 
 
 Map of coal region of Penn- 
 sylvania, 118.* 
 
 Leperditia, Anna, 81.* 
 
 of England, 120.* 
 
 Lepidodendra, 108, 127* 
 
 of N. America, Azoic, 73.* 
 
 Lepidodendron primsevum, 
 
 of N. America, Cretaceous, 
 
 107.* 
 
 196. 
 
 Lepidosteus, 51.* 
 
 of N. America, Tertiary, 
 
 Leptsena sericea, 88.* 
 
 217.* 
 
 transversalis, 97.* 
 Leptaanas, last of, 174, 200. 
 
 of New York and Canada, 
 71.* 
 
 Level, change of, in Greenland, 
 
 of United States, 69.* 
 
 243. 
 
 Marble 25. 
 
 changes of, in Age of Man, 
 
 Marcellus shale, 105. 
 
 241. 
 
 Marine formations, 287. 
 
 changes of, in Post-ter- 
 
 Marl, 22. 
 
 tiary, 226, 228, 249. 
 
 Marlite, 22. 
 
 origin of changes of, 318. 
 
 Marsupials, 50. 
 
 recent changes of, in 
 
 first of, 172. 
 
 Eastern N. America, 243. 
 
 Jurassic, 184,* 201. 
 
 recent changes of, in S. 
 
 Post-tertiary, 233. 
 
 America, 242. 
 
 Massive structure, 21, 31.* 
 
 recent changes of, in 
 
 Mastodon, Post-tertiary, 231.* 
 
 Sweden, 242. 
 
 Tertiary, 216. 
 
 Level. See ELEVATION. 
 
 Mastodonsaurus, 179.* 
 
 Lias, 166. 
 
 Mauna. See MOUNT. 
 
 Libellula, 177.* 
 
 Medina group, 94. 
 
 Life, agency of, in rock-making, 
 
 Megaceros Hibernicus, 230. 
 
 261. 
 
 Megalosaur, 181.* 
 
 Megathere, 232.* 
 Mer-de-glace, 292. 
 Mesozoic time, 162. 
 
 disturbances and progress, 
 
 248. 
 general observations on, 
 
 198. 
 
 geography of, 198. 
 life of, 200. 
 
 Metallic veins, 30, 317. 
 Metamorphic rocks, 21, 23. 
 Metamorphism, nature and 
 
 cause of, 312. 
 Azoic, 75. 
 during the Appalachian 
 
 revolution, 156. 
 Mica, 16. 
 
 schist, 23. 
 
 Michigan coal area, 117. 
 Microdon bellistriatus, 112 * 
 Microscopic organisms, 59,* 
 
 61 * 263. 
 formation of deposits of, 
 
 265. 
 
 Mind, Era of, 236. 
 Mineral coal. See COAL. 
 
 oil, 124. 
 Miocene, 206. 
 Mississippi River, completed, 
 
 amount of water of, 274. 
 
 detritus of, 279. 
 Missouri coal area, 117. 
 
 iron-mountains of, 74. 
 Moa, extinction of, 241. 
 Mollusks, 49, 54* 
 Monkeys, first of, 236. 
 
 Tertiary, 216. 
 Monoclinal, 42. 
 Monocotyledons, 62. 
 Moraines, 294.* 
 Mosaic cosmogony, 77, 93, 260. 
 Mosasaur, 195.* 
 Mountains, elevation of, 218, 
 318. 
 
 of Paleozoic origin, 148. 
 
 made after the close of the 
 Paleozoic, 154. 
 
 made after the Cretaceous 
 period, 204. 
 
 See ELEVATIONS. 
 Mount Blanc, 292. 
 
 Holyoke, 165, 311. 
 
 Kea, 301. 
 
 Loa, 301* 
 
 Rosa glaciers, 293. 
 
 Tom, 311. ' 
 Muck, 265. 
 Mud-cones, 310. 
 Mud-cracks, 33, 80, 102, 145. 
 Muschelkalk, 166. 
 Myriapods, first of, 130.* 
 
 Nautilus, 55.* 
 
 Nautilus tribe, number of ex- 
 tinct specie* of, 252. 
 
INDEX. 
 
 353 
 
 New Brunswick coal area, 117 
 Niagara Falls, rocks of. 27, 
 95.* 
 
 group, 94. 
 
 period, 94. 
 
 River, gorge of, 277. 
 North America, form of, 9. 
 
 geography of. See GEO 
 
 GRAPHY. 
 
 Norwich crag, 209. 
 Notidanus primigenius, 52.* 
 Nova Scotia coal area, 117. 
 Nummulites, 59.* 
 Nummulitic limestone, 208. 
 
 Occident, characteristics of, 5. 
 Ocean, depression of, 6, 7. 
 
 effects of, 283. 
 Oceanic basin, origin of, 329. 
 
 waves, earthquake, 325. 
 Ohio, coral reef of Falls of, 105 
 Oil, mineral, 124. 
 Old red sandstone, 106. 
 Oneida conglomerate, 94. 
 Onondaga limestone, 105. 
 Oolite, 25, 166. 
 Ophileta levata, 81.* 
 Orbitolina Texana, 191* 
 Orient, characteristics of, 5. 
 Origin of species. See CREATION 
 Oriskany period, 104. 
 
 sandstone, 104. 
 Orthis biloba, 97 * 
 
 occidental is, 88.* 
 
 testudinaria, 88.* 
 Orthoceras, 83.* 
 
 last of, 175, 200. 
 Orthoclase, 15. 
 
 Osmeroides Lewesiensis, 194.* 
 Ostracoids, 54,* 82.* 
 
 of Triassic, 169.* 
 Ostrea sellseformis, 211.* 
 Otozoum Moodii, 171.* 
 Outcrop, 39.* 
 Ox, first of, 216. 
 Oyster, Tertiary, 211,* 212. 
 
 Packing specimens, 346. 
 Palfeaster Niagarensis, 57.* 
 Palaeoniscus lepidurus, 51.* 
 
 Freieslebeni, 51,* 133.* 
 Palaeosaurus Carolinensis,170.* 
 Paleothere, 214* 
 Paleozoic time, 78. 
 
 disturbances closing, 154. 
 
 general observations on, 
 
 142. 
 
 Palephemera medifeva, 170.* 
 Palisades, 165, 186, 312. 
 Palms, first of, 188, 190, 202. 
 
 Tertiary, 210.* 
 Palpipes priscus,178.* 
 Paludina Fluviorum, 174.* 
 Paradoxides Harlani, 81.* 
 Paris basin, Tertiary animals 
 of, 208, 214.* 
 
 Paumotu Archipelago, 269. 
 Peat, formation of, 263. 
 Peccary, fossil, 215. 
 Pecopteris Stuttgartensis,168.' 
 Pemphix Sueurii, 178* 
 Pentamerus galeatus, 98.* 
 
 oblongus, 97.* 
 Pentremites, first of, 130.* 
 Permian period, 116, 125. 
 Petraia Corniculum, 89.* 
 Petroleum. 12-1. 
 Phacops Bufo, 111.* 
 Phascolotherium, 183.* 
 Phenogams, 61. * 
 
 Phonolite, 304 
 Phyllopods, 82. 
 Physiographic Geology, 5. 
 Plants, 47, 60. 
 
 Carboniferous, 126.* 
 earliest marine, 76, 80. 
 earliest terrestrial, or De- 
 vonian, 99,* 107.* 
 Tertiary, 210.* 
 Triassic, 167.* 
 Platyceras angulatum, 97.* 
 Plesiosaurs, ISO,* 195. 
 Pleurotomaria lenticularis 
 
 88* 
 
 tabulata, 131.* 
 Pliocene, 206. 
 Pliosaur, 180. 
 
 Podozamites lanceolatus, 168.= 
 Polycystines,. 59,* 263. 
 Polyps, 58.* 
 Polythalamia, 59.* 
 Pompeii, 309. 
 
 orphyry, 26, 311. 
 Portland (England) dirt-bed 
 
 166. 
 (Connecticut) freestone 
 
 164. 
 Post-tertiary period, 219. 
 
 changes of level, 249, 331. 
 general results of, 234. 
 r'otsdam period, 79. 
 Mmordial period, 79. 
 r'rionastraea oblonga, 173.* 
 ) roductus Rogersi, 131.* 
 rotophytes, 60.* 
 rotozoans, 49, 58,* 190. 
 terichthys, 113.* 
 terodactyl, 181,* 195. 
 Pterophyllum graminoides, 
 
 168.* 
 
 teropods, 56* 
 >terosaurs, 181.* 
 *udding stone, 22. 
 ~*upa vetusta, 131.* 
 ) yroxene, 16. 
 
 Quadrupeds. See MAMMAL. 
 tuarternary. See POST-TER- 
 TIARY. 
 Quartz, 14.* 
 
 uartz rock, or Quartzite, 24. 
 tuercus, Tertiary, 210.* 
 
 Radiates, 49, 57* 
 Rain-prints, 33,* 145. 
 Raniceps Lyellii, 134. 
 Reefs, coral, 266.* 
 
 sand, 287, 289. 
 Regelation, 294. 
 Reptiles, 50. 
 
 first of, 134. 
 
 Mesozoic, 171 * 178 * 195 * 
 201. 
 
 tracks of, 171.* 
 Reptilian age, 162. 
 Rhinoceroses, Tertiary, 215 * 
 
 216. 
 Rhizopods, 59 * 
 
 Cretaceous, 190.* 
 
 formation of deposits by 
 
 263, 265. 
 
 Rhode Island coal area, 117. 
 Rhynchonella cuneata, 97.* 
 
 ventricosa, 98.* 
 Rill-marks, 33,* 102, 189. 
 Ripple-marks, 33,* 80, 102,145, 
 
 289. 
 Rivers, action of, 273. 
 
 of Paleozoic origin, 148. 
 River terraces, 225.* 
 Rock, definition of, 14. 
 Rocks, constituents of, 14. 
 
 formation of sedimentary, 
 
 kinds of, 20. 
 
 of Mississippi Valley, see- 
 
 tion of, 143* 
 of New York, section of, 
 
 66,* 70,* 95,* 96,* 106.* 
 origin of Paleozoic, 144. 
 thickness of Paleozoic, in 
 
 North America, 142, 249. 
 Elocky Mountains, origin of, 
 
 198, 203, 217, 249. 
 Mountain coal area, 117. 
 Rotalia, 59,* 192. 
 
 St. Lawrence River in the Post- 
 tertiary, 226, 227. 
 Saliferous group, of Britain 
 and Europe, 166. 
 
 rocks of New York, 95. 
 Salina rocks, 95, 101. 
 Salisbury craigs, 311. 
 Salix Meekii, 191.* 
 Salt of coal formation, 124. 
 
 of Salina, &c., 95. 
 
 of Triassic, 166. 
 Sand, 20. 
 
 Sand-banks, 287, 289. 
 Sand-scratches, 273. 
 Sandstones, 22. 
 Sapphire, 15. 
 
 Sassafras Cretaceum, 191.* 
 Bauropus primaevus, 134.* 
 Scaphites larvaeformis, 193.* 
 Jchist, schistose rocks, 21, 22. 
 Schoharie grit, 104. 
 Scolithus linearis, 83. 
 
854 
 
 INDEX. 
 
 Scoria, 26. 
 
 Stalagmite, 25. 
 
 ^rap, columnar, 311.* 
 
 Scorpions, first of, 130. 
 Scouring-rush, 60. 
 
 Star-fishes, 58* 
 Statuary marble, 25. 
 
 .Yavertine, 21. 
 tree-ferns, 126.* 
 
 Seaweeds, 60. 
 
 Steatite, 17. 
 
 Trenton Falls, period, 85. 
 
 (Section of New York rocks, 
 
 Stigmarise, 129.* 
 
 rocks of, 86. 
 
 70.* 
 
 Strata, definition cf, 28. 
 
 Triassic period, 163, 164. 
 
 of the series of rocks, 66.* 
 
 origin of, 37. 
 
 rocks, origin of American, 
 
 Sections of Paleozoic rocks, 
 143,* 157,* 158* 
 
 positions of, 36,* 43. 
 Stratification, 27,* 31.* 
 
 185. 
 Mgonia clavellata, 174.* 
 
 Sedimentary beds, formation 
 
 Strike, 41* 
 
 Crigonocarpum tricuspida- 
 
 of, 296. 
 
 Subcarboniferous period, 116, 
 
 tum, 127.* 
 
 Selachians, 52.* 
 
 121. 
 
 Trilobites, 54,* 150. 
 
 Devonian, 111.* 
 Serpentine, 17. 
 
 Submarine eruptions, 309. 
 Subsidence of coast of New 
 
 Devonian, 110.* 
 number of extinct, 252. 
 
 Shale, 21, 22, 31. 
 
 Jersey, 243. 
 
 Silurian, 81,* 89,* 97.* 
 
 Sharks, 52.* 
 
 of Greenland, recent, 243. 
 
 Tufa, 23, 303. 
 
 teeth, 52,* 178, 212. 
 
 Subsidences of volcanic re- 
 
 Turrilites catenates, 193.* 
 
 SigillariEe, 62, 109. 
 Carboniferous, 128.* 
 
 gions, 309. 
 Subterranean waters, 281. 
 
 Turritella carinata, 211.* 
 Turtle of India, 213. 
 
 Devonian, 107.* 
 
 Suffolk crag, 209. 
 
 Turtles, Jurassic, 183. 
 
 Silica, or Quartz, 14. 
 
 Syenite, 23. 
 
 Tertiary, 216. 
 
 Silicates, 15. 
 
 Synclinal, 42.* 
 
 
 Siliceous shells, microscopic, 
 
 Syringopora Maclurii, 111.* 
 
 Unconformable strata, 43.* 
 
 59*, 61,* 263. 
 
 
 Under-clays, 122. 
 
 waters of Geysers, 309. 
 Silt, 279. 
 
 Talc, 17. 
 Talcose schist, 23. 
 
 Univalves, 55.* 
 [Jnstratified condition, 28.* 
 
 Silurian age, 78. 
 Siphonia lobata, 192.* 
 Slate, 21, 24. 
 
 Teliost fishes, 50* 
 Teliosts, first of, 188, 194,* 202, 
 Tertiary, 212. 
 
 Upper Helderberg, 105. 
 Upper Missouri region, fossil 
 quadrupeds of, 215.* 
 
 Slaty cleavage, 36,* 323. 
 Sloths, gigantic, of Post-ter- 
 tiary, 232 * 
 
 Tentaculites, 98.* 
 Terrace epoch, 220. 227. 
 Terraces on Connecticut River, 
 
 Missouri Tertiary, 207. 
 Ursus spelams, 230. 
 Utica shale, 87. 
 
 Snakes, first of, 213. 
 no Jurassic, 183. 
 
 225.* 
 of Scotland. 229. 
 
 Valleys, formation of, 274. 
 
 Soapstone, 17. 
 Solenhofen lithographic lime- 
 stone, 166. 
 
 origin of, 227. 228 * 
 Tertiary period, 206. 
 general results of, 234. 
 
 Veins, 29* 
 formation of, 316. 
 Vertebrates, 49, 50. 
 
 fossils from, 177. 
 
 in America, 207. 
 
 first of, 107, 258. 
 
 Solfataras, 309. 
 South America, form of, 9. 
 Species, exterminations of, 93, 
 150, 200, 202, 256. 332. 
 introduction of, 149, 256. 
 
 of England, 209. 
 [etradecapods, 53.* 
 Tetragonolepis, 179.* 
 Thallogens, 60. 
 Thanet sands, 209. 
 
 Vesuvius, 308. 
 Vicksburg epoch, 206. 
 Vivipara Fluviorum, 174.* 
 Volcanoes, distribution of, 300. 
 nature of, 301. 
 
 origin of, 92, 116, 152, 256. 
 permanency of, 152. 
 Specimens, on collecting and 
 packing, 346. 
 Sphenopteris laxus, 107.* 
 Gravenhorstii 127.* 
 
 Thecodonts, 135. 
 Thickness of rocks in Appa- 
 lachian region, 102. 
 of stratified rocks, 44. 
 Thrissops, 51.* 
 Tidal currents, 285. 
 
 Water, action of, 273. 
 Waters,, subterranean, 281. 
 freezing and frozen, 290. 
 Waves, action of, 283. 
 Wealden, 166. 
 
 Spicules of Sponges, 58, 110 * 
 
 Time, length of geological, 244, 
 245. 
 
 Wenlock limestone, 96. 
 Whales, first of, 213. 
 
 192. 
 Spiders, first of, 177* 
 Spinax Blainvillii, 52* 
 Spine of a fish, 113 * 133* 
 
 Time-ratios, 145, 198, 243. 
 Titanothere, 215.* 
 Tourmaline, 17.* 
 
 Wind-drift structure, 32* 
 Woolwich beds, 209. 
 Worms, 53,* 83. 
 
 Spirifer cameratus, 131.* 
 macropleurus, 98.* 
 
 Trachyte, 26. 
 Tracks of birds, 172.* 
 
 Xylobius Sigillarias, 132* 
 
 mucronatus, 112.* 
 Niagarensis, 97.* 
 Walcotti, 174 * 
 
 Cheirotherium, 179.* 
 of insects, 170* 
 of reptiles in Carboni- 
 
 Yoldia limatula, 212 * 
 Yorktown epoch, 206. 
 
 Spirifers, last of, 174,* 200. 
 Sponge, Cretaceous, 192.* 
 
 ferous, 134.* 
 of reptiles, Triassic, 171. 
 
 Zamia, 62. 
 
 Sponges, 58. 
 Sponge-spicules, 58, 110, 192. 
 in hornstone, 110.* 
 Stag family, first of, 236. 
 Stalactites, 25. 
 
 of Trilobites, 81* 
 Transportation by rivers, 277. 
 Trap, 26. 
 of Connecticut valley, &c. 
 165. 
 ^^uaemsss^*^ 
 
 leaf of, 167.* 
 Zaphrentis bilateralis, 97 * 
 Rafiuesquii, 111* 
 Zeacrinus elegans, 131.* 
 Zeuglodon, 214. 
 
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