Full text of "Geology"
GIFT OF
Dean Frank H. Probert
Mining Dept,
AMERICAN SCIENCE SERIES— ADVANCED COURSE
GEOLOGY
BY
THOMAS C. CHAMBERLIN AND ROLLIN D. SALISBURY
Heads of the Departments of Geology and Geography, University of Chicago
Members of the United States Geological Survey
Editors of the Journal of Geology
IN THREE VOLUMES
VOL. III. EARTH HISTORY
MESOZOIC, CENOZOIC
SECOND EDITION, REVISED
NEW YORK
HEKEY HOLT AND COMPANY
1907
.
FflANK H
MINiW
H.
Copyright, 1906
BY
HENRY HOLT AND COMPANY
ROBERT DRUMMOND, PRINTER, NEW YORK
CONTENTS.
VOLUME III.
MESOZOIC ERA.
CHAPTER XII.
THE TRIASSIC PERIOD.
PAGB
FORMATIONS AND PHYSICAL HISTORY . . . . , 1
The Triassic System (Newark Series') of the East , . . 2
Distribution, 2. The rocks of the Newark series, 4. The
conglomerates, 4. The sandstone and shale, 6. Conditions
of origin, 7. Former extent, 9. Subdivisions, 10. Igneous
rocks associated, 10. Structure, 11. Thickness, 17. Corre-
lation, 17. Physiography of the Newark of New England and
New Jersey, 19.
The Triassic in the West 24
The deposits of the western interior, 24. Thickness, 27.
The Triassic system on the Pacific slope, 27.
Climatic Conditions 29
Close of the Trias 29
Foreign Triassic 30
Europe, 30. Germany, 31. England, 33. Sweden, and
Russia, 34. Southern Europe, 35. Asia, 37. South America,
37. Africa and Australia, 38.
THE LIFE OF THE TRIASSIC PERIOD 38
The Plant Life 38
The dominance of the gymnosperms, 38.
The Land Animals 41
The rise of the dinosaurs, 43. The advanced differentia-
tion of the chelonians, 43. The advent of the non-placental
mammals, 44. The reptiles go down to sea, 45.
The Marine Life 48
The transition tracts, 48. The transition faunas, 49.
General nature of the faunal change, 50. The earlier Triassic
iii
iv CONTENTS.
PAQD
faunas, 52. The middle Triassic faunas, 54. The later Trias-
sic faunas, 55. General nature of the fauna, 55. The
cephalopods again in leadership, 56. Old and new gastropod
types, 56. The transition and rise of the pelecypods, 56.
The change in the type of brachiopods, 57. The echinoids
become the leading echinoderms, 57. The corals, 57. Other
forms, 57.
CHAPTER XIII.
THE JURASSIC PERIOD.
FORMATIONS AND PHYSICAL HISTORY 59
The eastern part of the continent, 59. The western part
of the continent, 61. The Lower and Middle Jurassic of the
Pacific coast, 61. Lower and Middle Jura in the western in-
terior, 63. The Upper Jurassic, 64. Surface distribution and
position of beds, 67. Jurassic in Alaska, 67.
Close of the Jurassic, in America 67
Orogenic movements, 67. Changes in geography, 69.
Foreign Jurassic T-T 70
Europe, 70. Lower Jura or Lias, 72. Middle Jura, 73.
The Upper Jura, 74. Extra-European Jurassic, 77. Arctic
lands, 77. Asia, 77. Africa, 77. Australia, 78. Central
and South America, 78.
Coal 78
Geography of the Jurassic Period 78
Climate 79
Close of the Jurassic, in Europe 79
THE JURASSIC LIFE 80
The Marine Life 80
Marine reptiles, 86. The American marine faunas, 90.
The northern and more interior province, 92.
The Land Life 94
I. The Vegetation -. 94
II. The Land Animals 95
Classificatory difficulties, 95. The Jura-Comanchean
development of the land vertebrates, 97. The dominance
of the dinosaurs, 97. Other reptilians, 100. The advent
of aerial life; the pterosaurs, 101. The appearance of true
birds, 102. The non-placental mammals, 103. The in-
sects, 104.
CONTENTS. V
CHAPTER XIV.
THE COMANCHEAN (LOWER CRETACEOUS) PERIOD.
PAGE
FORMATIONS AND PHYSICAL HISTORY 106
Introductory 106
The Comanchean (Shastan, Lower Cretaceous) System 108
The Atlantic and Gulf Border regions, 108. Constitution
and structure of the Potomac and Tuscaloosa series, 112.
Stratigraphic relations, 114. Thickness, 115. The Texas
region, 115. Westward and northward extension, 117. In
Mexico, 118. The Northern Interior, 119. The Pacific
Border, 122. In the United States, 122. North of the
United States, 123. Panama, 124.
The Close of the Comanchean (Lower Cretaceous) Period 124
The Lower Cretaceous in Other Continents. 125
In Europe, 128. Other continents, 129. Climate, 129.
Close of the Period 130
THE LIFE OF THE COMANCHEAN PERIOD 130
The terrestrial vegetation, 130. The introduction of
angiosperms, 130. The land animals, 133. The fresh-water
fauna, 134. The marine faunas, 134.
CHAPTER XV.
THE (LATER) CRETACEOUS PERIOD.
FORMATIONS AND PHYSICAL HISTORY 137
The Atlantic Border Region 137
Thickness, 140. Classification, 140. Changes in the beds
since deposition, 140. The Gulf border region east of the
Mississippi, 140. The western Gulf border region, 142.
The Western Interior 144
The Dakota formation, 144. The Colorado series, 148.
The origin of chalk, 149. The Montana series, 151. The
Laramie series, 152. Transition beds between Mesozoic and
Cenozoic, 154. Coal, 159. Thickness of the (Upper) Creta-
ceous system, 160.
The Pacific Coast 160
Climate. . , 161
VI CONTENTS.
PAGE
Close of the Period 161
General movements, 162. Orogenic movements, 162.
Faulting, 164. Igneous eruptions, 167.
Upper Cretaceous of Other Continents 167
Europe, 167. Asia, 170. Africa, 171. South America,
171. Australia, 171.
Climate 172
LIFE OF THE (UPPER) CRETACEOUS 172
The Land Life 172
The vegetation, 173. The land animals, 175. The
dinosaurs, 176. Turtles, lizards, snakes, and crocodiles, 178.
The pterosaurs, 179. The slight progress of the mammals, 179.
The Sea Life 180
The sea saurians, 180. The sea serpents, 180. The sea
turtles, 180. The sea birds, 182. The seaward movement,
185. The marine fishes, 185. The marine invertebrates, 186.
Special faunas, 187.
THE CENOZOIC ERA.
CHAPTER XVI.
THE EOCENE PERIOD.
INTRODUCTORY: BASIS OF CENOZOIC CLASSIFICATION 191
FORMATIONS AND PHYSICAL HISTORY OF EOCENE PERIOD 196
The Eastern Coast 198
The Atlantic coast, 198. The Gulf border, 199. Western
Gulf region, 200.
The Pacific Coast 200
Marine beds, 201. Brackish-water beds, 202. North of
Washington, 203. Terrestrial formations, 204. Igneous
activity, 212.
General Considerations 212
Close of the Eocene in North America 214
Foreign 215
Europe, 215. Other continents, 219. General geography
of the Eocene, 220. Close of the Eocene, 221.
THE EOCENE LIFE 221
The Transition from the Mesozoic to the New Era 221
CONTENTS. vii
PAGE
The Eocene Vegetation 226
The temperate (?) flora of the earliest Eocene, 226. The
tropical (?) flora of the Middle Eocene, 226. The flora as
food-supply, 227.
The Land Animals 228
The undifferentiated nature of the early Eocene placentals,
228. The main herbivorous line, 230. Side branches that
became extinct, 232. The divergence of the ungulates into
odd- and even-toed, 233. The deployment of the artiodactyls,
236. The development of the carnivores, 236. The emergence
of the edentates, 238. The ancestral rodents, 238. The primi-
tive insectivores, 239. The primates (Quadrumana), 239.
The mammals go down to sea, 239. The non-placentals, 240.
The birds, 240. The reptiles and amphibians, 240. The
insect life, 240.
The Marine Life 241
THE OLIGOCENE EPOCH 242
Formations and Physical History 242
In North America 242
Foreign 248
Europe, 248. Amber, 251. Bohnerz, 252. Other con-
tinents, 252.
The Life of the Oligocene 252
The vegetation, 252. The land animals, 253. The marine
life, 257.
CHAPTER XVII.
THE MIOCENE PERIOD.
FORMATIONS AND PHYSICAL HISTORY 258
The Atlantic coast, 258. The Brandon formation, 261.
The Gulf coast, 261. The Pacific coast, 262. Non-marine
deposits, 264. Igneous activity during the Miocene, 270.
Close of the Miocene, 273.
Foreign 276
Europe, 276. Close of the Miocene in Europe, 279. Other
continents, 280. Arctic latitudes and climate, 281.
THE LIFE OF THE MIOCENE 282
The Land Plants. . .282
viii CONTENTS.
PAOB
The Land Animals ' 283
The earlier fauna, 283. The later fauna: the elephants,
284. The immigration of the ruminants, 285. The camels,
oreodons, and peccaries, 286. The evolution of the horse, 286.
The tapirs and rhinoceroses, 289. The carnivores, 289. The
primates in the Old World, 289. The marsupials, 290. The
lower vertebrates, 290. Summary, 290.
The Marine Life 290
Provincialism dominant, 290.
CHAPTER XVIII.
THE PLIOCENE PERIOD.
FORMATIONS AND PHYSICAL HISTORY 296
The Lafayette Formation 301
Thickness, 303. Constitution, 303. Color, 304. Partial
removal of the formation, 304. Fossils, 305. Genesis, 305.
Marine Pliocene Beds 308
The Atlantic coast, 308. The Gulf coast, 309. The Pacific
coast, 309.
Crustal Movements of the Pliocene 311
Foreign 318
THE LIFE OF THE PLIOCENE 320
The land plants, 320. The land animals, 321. The marine
life, 326.
CHAPTER XIX.
THE PLEISTOCENE OR GLACIAL PERIOD.
FORMATIONS AND PHYSICAL HISTORY 327
General Distribution of Glaciation 327
The Glaciation of North America 330
The centers of glacial radiation, 330. Mountain glaciation,
333. Island glaciation, 336. Summary, 337.
The Criteria of Glaciation *. .- 337
The constitution of the drift, 338. The bowlders and
other stones of the drift, 340. Structure of the drift, 341.
Distribution of drift, 343. Topography of the drift, 344.
Thickness of the drift, 346. Contact of drift and underlying
rock, 346. Striation and planation, 346. The shapes of rock
hills, 351. Summary, 351.
CONTENTS.
PAGE
The Development and the Thickness of the Ice-sheets 355
Stages in the history of an ice-sheet, 358.
The Work of an Ice-sheet 358
Formations made by the Ice-sheets 359
The ground moraine, 360. A terminal moraine, 362.
Development of terminal moraine topography, 365.
Fluvioglacial Deposits 368
At the edge of the ice, 368. Beyond the edge of the ice,
371. Gradational types: pitted plains, patches of gravel and
sand, 373. Beneath the ice, 373. Deposits of superglacial
and englacial streams, 376.
Relations of Stratified to Unstratified Drift 377
Extraglacial deposits, 377. Supermorainic deposits, 377.
Submorainic (basal) deposits, 377. Intermorainic stratified
drift, 378. Topographic distribution of stratified drift, 378.
Changes in Drainage Effected by Glaciation 379
The Succession of Ice Invasions 382
The sub-Aftonian, or Jeresyan, glacial stage, 384. The
Aftonian interglacial stage, 384. The Natchez formation, 386.
The Kansan glacial stage, 388. The Yarmouth interglacial
stage, 389. The Illinoian glacial stage, 391. The Sangamon
interglacial stage, 391. The lowan glacial stage, 391. The
Peorian interglacial stage, 392. The Earlier Wisconsin glacial
stage, 392. The fifth interval of recession, 393. The Later
Wisconsin glacial stage, 393. The glacio-lacustrine substage,
394. The Champlain substage, 403.
The Loess 405
Origin, 409.
The Duration of the Glacial Period 413
Foreign. 421
The Cause of the Glacial Period 424
Hypsometric Hypotheses 424
The hypothesis of elevation, 424.
Astronomic Hypotheses 426
CrolPs hypothesis, 426. Other astronomical hypotheses,
431. The hypo hesis of a wandering pole, 431.
Atmospheric Hypotheses 432
Variations in depletion the working factor, 432. Local-
ization, 433. Periodicity, 433. Variations in supply the
working factor, 445. Proximate hypotheses, 445.
X CONTENTS.
PAGE
Formations Outside the Ice-sheets '. 446
On the Atlantic and Gulf coasts, 447. Stratigraphic rela-
tions, 451. Fossils, 451. In the interior, 454. In the west,
455. Lacustrine deposits: Lake Bonne ville, 455. Lake
Lahontan, 463. Mono Lake, 467. Glacial deposits, 467.
Glacial lake deposits, 469. Topographic unconformity, 471.
Alluvial and talus deposits, 472. Eolian deposits, 474.
Deposition from solution, 475. Marine deposits, 476. Igne-
ous rocks, 477.
Changes of Level During the Pleistocene 480
Foreign 483
THE LIFE OF THE PLEISTOCENE PERIOD 483
Destructive effects of glaciation, 483. To-and-fro migra-
tion, 485. Definite climatic zones, 486. Climatic adapta-
tions, 486. Superposition of cold and warm faunas and floras
in the record, 487. Mixing of relics, 488. Real intermingling
of northern and southern species, 488. Cave deposits, 488.
Existing Alpine remnants of the migrations, 489.
Life of the Interglacial Stages 490
The Toronto beds, 490. Other interglacial epochs, 493.
Marine life onthe more nor therly coasts, 494. Marine life on
the more southerly coasts, 495.
The Terrestrial Life of the Non-glacial Regions 495
The boreal group, 496. The southern group, 498.
The European Pleistocene Life 498
Oscillatory migrations, 498.
The Pleistocene Life of the Southern Hemisphere 500
Life in South America, 500. Australian life, 501. Life
in Africa, 501.
Man in the Glacial Period 502
In America, 502. Sources of good evidence, 512. In
Europe, 513. Other references relative to the antiquity of
man, 516.
CHAPTER XX.
THE HUMAN OR PRESENT PERIOD.
GENERAL CONSIDERATIONS 517
The end of the Glacial period, 517. Future glaciation, 517.
The end of the deformation period, 518. The suggestions of
CONTENTS. xi
PAGE
existing physiography, 519. The channels on the continental
borders, 521. Upward warping near the coasts, 523. The
apparent imperfection of the geologic series on the continental
borders, 523.
The Behavior of the Continental Borders 526
The effects of body deformation, 526. The movement of
the outer shell, 526. The reverse movement of the shell, 527.
The movement of sediments on the continental edges, 527.
Cooperative water-displacement, 528. Tidal cooperation, 528.
Cooperative agency of the ice-sheets, 529.
THE LIFE OF THE HUMAN PERIOD 530
The re-peopling of the glaciated areas, 530. The rate of
re-distribution, 533.
The Dynasty of Man 534
Human dispersal, 534. Provincialism giving place to cos-
mopolitanism, 540. Man as a geological agency, 541. Prog-
nostic geology, 542.
APPENDIX.
SELECTED SECTIONS OF STRATA 545
Section in West Central Massachusetts, 546. Section in
Eastern West Virginia and Western Virginia, 548. Section
in Eastern Tennessee, 549. Section in Northeast Alabama
and Northwest Georgia, 551. Section in Central Tenness e,
552. Section for Southern Michigan, 553. Generalized Sec-
tion for Ohio, 554. Generalized section for Indiana, 556.
Generalized section for Iowa, 558. Section for Arkansas, 560.
Section in Indian Territory, 562. Generalized section for
Nebraska, 564. Section in Eastern Wyoming, 565. General-
ized section for the Black Hills, 560. Section in Central Mon-
tana, 568. Section in West Central Colorado, 570. General-
ized section for Southwestern Colorado, 572. Generalized
section for the Grand Canyon Region, 574. Section in Arizona,
575. Section in the Eureka District, Nevada, 576. Section
in Southern California, 577. Section in Central Washington,
578.
GEOLOGY.
THE MESOZOIC ERA.
CHAPTER XII.
THE TRIASSIC PERIOD.
THE crustal movements which affected the North American con-
tinent during the closing period of the Paleozoic era, and the accom-
panying changes in geography, have been noted. From the area
between the growing Appalachians and the Great Plains the sea was
excluded. The surface of Appalachia, lying east of the Appalachian
Mountains, and extending eastward perhaps beyond the present
coast, the land which throughout the Paleozoic era had furnished
sediments to the sinking trough where the Appalachian Mountains
were to arise, suffered deformation during the closing stages of the
Paleozoic or soon after, and parts of its surface were converted into
areas of deposition. These areas were in the form of long and rela-
tively narrow troughs, roughly parallel to the present coast. In them,
sediments from the surrounding land were laid down, and constitute
the only representative of the Triassic system known in the eastern
part of the continent. It is not known that the deformation of the
surface of Appalachia brought any part of the present land area beneath
the ocean.
In the west, the geographic changes which marked the transition
from the Paleozoic were scarcely less important. The more or less open
sea of the western interior during the Mississippian and Pennsylvanian
periods was largely excluded at the close of the Carboniferous. In
the Permian period, it is true, the sea had at least temporary access
to an extensive area in the western interior (Vol. II, p. 621); but
in the Triassic period the open sea seems to have been completely
excluded from this region, though there were still considerable areas
of sedimentation between the meridians of 100° and 113°. Some
GEOLOGY.
of these areas were the sites of salt seas, and some of fresh lakes, while
still others may have been free from standing water. Within the gen-
eral area of deposition, many areas of relatively high land probably
interrupted the continuity of the sedimentation.
At about the time when the open sea was generally excluded from
the western interior, the ocean began to creep in on the western border
of the continent, and the shore of the Pacific was presently shifted
eastward to the 117th meridian in the latitude of Nevada.
As a result of these changes in geography, the Triassic strata are
known in three regions: (1) The Atlantic slope east of the Appala-
chians; (2) the western interior; and (3) the Pacific coast. The
strata in these three regions are so widely separated, and in many
ways so unlike, that they will be considered separately.
THE TRIASSIC SYSTEM (NEWARK SERIES) OF THE EAST.
Distribution. — From Nova Scotia on the north to South Carolina
on the south there is a series of belts or patches of rock of Triassic
age, representing the oldest post-Paleozoic system on the eastern side
of the continent. The beds of these several areas have been grouped
under the name Newark1 (from Newark, N. J.).
The areas where the strata of the system are now exposed are
shown on the accompanying map (Fig. 307). Of their existence east
of their exposures nothing is known.
It will be observed that the belts and patches where Newark strata
come to the surface are mostly elongate in a northeast-southwest
direction, and that their longer axes are roughly parallel to the Appa-
lachian Mountains and to the present coast line. Of the series, there
may be said to be four principal areas. These are: (1) the area about
the Bay of Fundy; (2) the area in the Connecticut River valley;
(3) the long belt extending from the Hudson River in the southern
part of New York, through New Jersey, Pennsylvania, and Mary-
land into Virginia; (4) a number of relatively small disconnected
areas in Virginia and North Carolina. From what has preceded, and
from the general principles already understood, it is needless to say
that the Newark series is unconformable on the older formations on
which it rests.
1 For an account of the Newark series see Russell, Bull. 85, U. S. Geol. Surv., 1892.
Full bibliography to date of publication.
THE TRIASSIC PERIOD.
FIG. 307. — Map showing the known distribution of the Triassic system in North
America (black areas), with conjectures as to its presence where buried (lined
areas), and its absence where it was once present (dotted areas).
4 GEOLOGY.
The Rocks of the Newark Series.1
The rocks of the Newark series are of various sorts, including all
the common varieties of fragmental rocks, some of which are here
developed in unusual phases. There are abundant conglomerates
and some breccias, though sandstones and shales make up the prin-
cipal mass of the series. Locally, the system contains a little lime-
stone, and in Virginia and North Carolina there is bituminous coal.
Elsewhere the shale is sometimes carbonaceous.
The conglomerates. — Wherever standing waters came to occupy
those parts of the old land surface which warping had brought low,
they found upon it a mantle of decomposed and partially decomposed
rock, out of which arose basal conglomerates, made up partly of the
local rock (crystalline schists), but largely of its most resistant part —
the material of the quartz veins which affected it. At the same time,
drainage from the adjacent lands doubtless contributed sediment
to the areas of deposition.
The conditions for conglomerate formation were present for long
periods in some places^ as shown by the thickness of the beds; but
they were present at the same place at different times, for the con-
glomerate is not simply basal. Thus along the northwestern border
of the series in New Jersey, beds of coarse conglomerate at various
horizons represent the shore phase of beds which grade out into sand-
stone, and even into shale. As now exposed, the conglomerates are
seen in greatest development along the eastern border of the New
England area, and along the western borders of the areas farther south.
The chief constituent of the Newark conglomerate is quartz, as
already noted, but in places it contains much quartzite and crystalline
schist. Again, in some places in New York and New Jersey, as well
as at points farther south, the principal constituent is limestone.
Locally (some parts of New Jersey) so little else enters into its make-up
that it is quarried and burned for lime. The masses of limestone
involved are occasionally several feet in diameter.
To appreciate the exceptional character of the conglomerate it
may be recalled that limestone, on decomposition, is mainly dis-
solved, the insoluble part only becoming available for sediments.
1 The Connecticut valley and New York-Virginia areas are best known, and the
descriptions of the formations here given apply especially to them.
THE TRIASSIC PERIOD. 5
This is usually fine and of an earthy nature, and gives rise to mud
beds; or if there be abundant chert in the limestone, the insoluble
residue may be coarse, giving rise to gravel. Under ordinary cir-
cumstances, streams do not break up limestone and transport it in
masses, giving rise to limestone conglomerate at their debouchures.
Had there been limestone cliffs against which the waves of the
Triassic waters beat, or had there been scarps, at the bases of
which talus from limestone accumulated, the occurrence of lime-
stone conglomerate would not be strange, for in such situations
conglomerate and breccia containing a large proportion of limestone
may be formed. But at most points where the limestone conglomerate
occurs, there is now nothing to indicate that the areas of Triassic sedi-
mentation were bordered by limestone. If they were, the surface
exposures of the original formation have been destroyed, while its
derivative formation remains. Either erosion (Figs. 308 and 309)
or faulting (Figs. 310 and 311) might accomplish this result. If there
FIG. 308. — Diagram illustrating the manner in which limestone conglomerate (below a)
might be formed along shore. lm= limestone. (Compare Fig. 309.)
was faulting while the deposition of the series was in progress, fault
scarps, involving limestone, may have appeared about the borders
of the area of deposition. In this case, waves and descending streams
might have provided the material for the limestone conglomerate.
With the limestone, there is more or less other material derived from
the local rock formations; but at some points there are occasional
bowlders which do not correspond with any known formation of the
region. That they had a distant origin cannot, however, be asserted.
They may have come from formations now concealed or destroyed.
The exceptional coarseness of the conglomerate, at least locally,
6
GEOLOGY.
has been thought to call for some exceptional means of transporta-
tion. On this ground, it was long since conjectured that it was formed
at a time when glaciers existed in the eastern part of the United States.
Furthermore, glacial action, if operative in regions where there was
limestone, might produce conglomerate comparable in constitution
to that here found. It should be noted, however, that it was the
supposed demand for some exceptional agent of transportation, rather
than any direct evidence, which suggested the existence of glacier
ice. The constitution of the conglomerate at most points, and especially
the characteristics of its constituent parts, do not seem to support the
suggestion. In general, the materials are too well assorted to be the
immediate product of glaciation, and the stones and bowlders are
FIG. 309. — Diagram showing how the limestone which gives rise to the conglomerate
might have been removed by erosion, leaving some of the limestone conglomerate.
not only not striated, but generally possess forms not characteristic
of ice- worn bowlders. These objections to the hypothesis of the glacial
origin of the conglomerate lose much of their force if the formation
be looked upon as a deposit in water to which glacial drainage con-
tributed; but in the absence of all certain evidence of glacial or glacio-
fluvial origin, it seems more prudent to regard the conglomerate as
an exceptional phase of a shore formation.
The sandstone and shale. — The great body of the Newark series
is sandstone and shale, and both possess three or four notable charac-
teristics. First, their prevalent color is red, though there are shales
which are black, and sandstones which are gray. Second, except
locally, the series is poor in fossils, and those which exist are of such
a character as to indicate that the beds were not accumulated in open
sea- water. Third, some of the sandstone contains a considerable
THE TRIASSIC PERIOD. 7
amount of feldspar, derived, no doubt, from the bordering areas of
metamorphic rocks. Fourth, both the sandstone and shale contain
considerable quantities of mica.
In general, it may be said that the crystalline schists adjacent
were the principal source of the materials entering into the clastic
part of this series, but where it borders formations of other sorts, they
made their appropriate contributions. The limestone and the coal
of the series are local, and of slight thickness.
FIG. 310.
FIG. 311.
Fig, 310 shows limestone conglomerate forming along shore, where waves beat
against a limestone cliff (Ini), while Fig. 311 shows how faulting might conceal the
limestone which furnished the material for the conglomerate. Subsequent erosion
might expose the limestone conglomerate, without exposing the formation from
which it was made.
Conditions of origin. — The character of the Newark formations and
their fossils, mainly land plants, footprints of reptiles, and fresh- or
brackish- water fishes, point to the conclusion that they are of continental
rather than of marine origin, though the precise manner in which they
were laid down is not known. That deformation of the surface of
Appalachia, which had been reduced nearly to planeness by erosion,
gave rise to elongated depressions in which the Triassic sediments were
8 GEOLOGY.
deposited, seems certain. The depressions may have been due to
warping or to faulting, or partly to the one and partly to the other
FIG. 312. — Diagram showing the development of a trough, now partly filled by
sediment, by warping.
(Figs. 312 and 313), and their development may have continued as
deposition proceeded. Some of them may have been the sites of broad
river valleys,1 which, in the general uneasiness which marked the close
of the Paleozoic era, were brought into such an attitude as to become
sites of deposition. It is to be noted that deposits of the type repre-
sented by the Newark series imply warping, rather than depression.
FIG. 313. — Diagram showing the development of a trough, by faulting.
The warping may have been the uplift of the surroundings of the areas
of deposition, rather than the depression of those areas; or it may have
involved the depression of the areas of deposition as well as the uplift
of their surroundings. The deposits now making in the Great Basin
afford some analogy. However formed, the depressions (relative) in
the surface of the present Piedmont region became the sites of lakes,
bays, estuaries, dry basins, or of aggrading rivers. Lacustrine, estua-
rine, and fluviatile conditions may have alternated from time to time
in the various troughs where sedimentation was in progress, and the
sea may have gained access to some of them from time to time.
Since the Trias of the Connecticut valley and of the areas south
and west of the Delaware are bordered on either side by older ter-
ranes, it is easy to see how the areas of deposition might have been
enclosed. But from the Hudson to the Delaware the series is bordered
1 Shaler and Woodworth, 19th Ann. Kept. U. S. Geol. Surv., Pt. II, pp. 399-407.
THE TRIASSIC PERIOD. 9
on the southeast by younger (Cretaceous) beds. The barrier which
shut in this area of Trias on the southeast has been buried, but its
position was probably not far from the present southeast boundary
of the Triassic system in New Jersey. The older rocks are at or near
the surface at various points along this line.
The considerable thickness of the sediments, together with the
decisive evidences of shallow-water or subaerial origin, such as ripple-
marks, sun-cracks, tracks of land animals, etc., which they bear, indi-
cate either that inclined deposition prevailed, or that subsidence of the
areas of sedimentation, either by bowing or faulting, accompanied the
deposition. For the adequate supply of the detrital material, it would
seem that the lands bordering the areas of deposition were raised, rela-
tively, as the troughs filled. These relations would account for the con-
tinued supply of coarse material which the series shows. Since the sedi-
ments were predominantly the products of the chemical decomposition
of the ancient rocks, rather than the product of mechanical disruption,
it is probable that the surrounding lands were not generally high.
The prevalent redness of the formations, their structure, the presence
locally of limestone not known to be of marine origin, the existence
of coal-beds in some regions, and the character and paucity of the fossils,
indicate that the sediments accumulated subaerially, or in water which
was neither altogether fresh nor altogether salt for any long period
of time. The general conditions of accumulation may have been
similar to those under which the Catskill formation was deposited at
an earlier time.
Former extent. — It is possible, and perhaps probable, that the
outlying areas of the Newark series from Virginia to South Carolina
were once connected with one another, and with the Virginia-New York
area, though such connection has never been demonstrated. It has
been suggested, though with little basis, that the Newark of the
Connecticut valley was once connected with that of Acadia. It has
been thought l that the New York- Virginia area was once connected
with the New England area, and that, as in the preceding case, the
separation was effected by erosion. This suggestion, however, does
not seem well founded. A formation of so great extent as such a
1 Russell, N. Y. Acad. Sci., Ann., Vol. I, 1878; and Am. Nat., Vol. XIV, 1880,
pp. 703-12; also Hobbs, Bull. G. S. A., Vol. XIII, pp. 139-148.
10 GEOLOGY.
connection would imply would possibly make it necessary to assign
to it a marine origin; but the paucity of fossils, and the character of
those which are found, are opposed to this suggestion. Furthermore the
nature of the series itself, and especially the fact that many of the beds
at the borders of the present areas seem to have been deposited near
shore, indicates that the strata were never as extensive as their union
into a single area would imply. That the several areas of the Newark
series have been reduced by erosion is certain from the occasional
outliers, but nothing now known proves that their original borders
were more than a few miles beyond their present borders.
South of New Jersey and Pennsylvania, the Newark beds are on
the whole less red than to the north, and contain less conglomerate
and more carbonaceous matter.
Subdivisions. — Until recently, the Newark series has not been sub-
divided, but it has now been shown that in New Jersey it is divisible
into three somewhat distinct formations.1 Of the lowest (Stockton),
arkose sandstone and conglomerate are the most characteristic sorts
of rock. A hard black shale (Lockatong) is the most conspicuous part
of the middle formation; while red shale and sandstone make up the
principal part of the uppermost (Brunswick). This classification has
not been extended beyond the State, though the same formations
cross the Delaware into Pennsylvania. In Connecticut, also, three
main divisions are recognized,2 and in the Richmond area two.3
Igneous rocks associated. — Associated with the sedimentary beds
of the Newark series there is much igneous rock. The igneous rock
occurs partly in dikes, but chiefly in sheets interbedded with the shales
and sandstones. Some of the sheets are extrusive, having been poured
out on the surface of the inferior beds and subsequently covered by
the superior ones; others are intrusive (sills), having been forced in
between the layers of sedimentary rocks after the latter were deposited.
In New England, the igneous rocks are mostly extrusive, while in
New Jersey the proportion of intrusive sheets is greater. Certain
isolated bodies of igneous rock may represent volcanic plugs. The
sheets of igneous rock (really diabase, though usually called trap)
vary in thickness from a few to several hundred feet.
1 Kiimmel, Ann. Kept, of the State Geologist of New Jersey, 1896.
2 Davis, 18th Ann. Kept. U. S. Geol. Surv., Pt. II.
3 Shaler and Woodworth, 19th Ann. Kept. U. S. Geol. Surv., Pt. II.
THE TRIASSIC PERIOD.
11
The means of distinguishing extrusive lava sheets from sills are
various, though all criteria are not usually applicable in any one spot.
Some of these criteria are as follows: (1) The upper surface of an ex-
trusive sheet is likely to be more or less scoriaceous; (2) the basal
portion of the sedimentary rock overlying an extrusive sheet is likely
to contain fragments derived from the igneous rock beneath; (3) the
base of the clastic bed above an extrusive sheet has not been baked
by the heat of the underlying lava. In the case of the intrusive lava
sheets, or sills, on the other hand, (1) the overlying sedimentary beds,
as well as those below, have been affected by heat; (2) the upper
portion of the lava is not likely to be notably scoriaceous ; (3) the over-
lying clastic beds do not contain fragments of the igneous rock; (4)
the upper part of the igneous rock may contain fragments of the over-
lying sedimentary rock; (5) intrusive sheets are likely to send off
small dikes or stringers of lava which cut through few or many of the
layers of the overlying sedimentary rock; and (6) the intrusive sheet
FIG. 314. — Diagram showing a sheet of intrusive rock (sill).
itself may cross layers. Fig. 314 shows some of the characteristics
of an intrusive sheet, or sill.
Structure. — The structure of the Newark series is generally mono-
clinical. In the Connecticut River valley1 the dip is 10° to 25° (usu-
ally 20° to 23°) to the eastward (Fig. 316). The strata are other-
wise somewhat deformed, though never closely folded. In addition
1 For an excellent summary of the Trias of Connecticut, see Davis, 7th Ann. Kept.
U. S. Geol. Surv. A fuller and later account is given in the 18th Ann. Rept., Pt. II.
See also Emerson, the Holyoke folio, U. S. Geol. Surv., and for the interesting Pom-
peraug area, Hobbs, 21st Ann. Rept. U. S. Geol. Surv., Pt. III.
12 GEOLOGY.
to the tilting and incipient folding, the series is extensively faulted,
and that in a somewhat complicated manner. Some of the faults are
strike faults (parallel to the strike), some dip faults (right angles to
the strike), while others are oblique in various degrees. There is
also a fault or a series of faults along the eastern margin of the series.
The faults, affecting as they do a series of variable hardness (the trap
being much harder than the clastic beds), have determined many of
the peculiar topographic features of the Connecticut River basin,
and some of the details of its outlines. The faulting has also given
FIG. 315. — Contact of intrusive rock with sedimentary. Palisade Ridge, N. J.
rise to very notable peculiarities of outcrop. This is best illustrated
by the outcrops of the trap sheets (Figs. 318, 319, and 321).
In the New York- Virginia area the structure is likewise mono-
clinal, but the general direction of dip is to the northwest (10°- 15°).
This contrast of dips between the New England and New Jersey areas
was thought to give color to the hypothesis that the strata of the two
areas are parts of one huge anticline from the broad crest of which
the beds have been removed. As in New England, the beds of the
New York- Virginia area are never closely folded, though several broad
anticlines and synclines have been shown to exist. The series of this
area is also extensively faulted, the total number of faults known in
THE TRIASSIC PERIOD.
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GEOLOGY.
New Jersey and New York alone being about 75.1 Most of these
faults are small, but two of them are of the first order. These two
FIG. 317. — Section showing the structure of the Newark series, just north of Holyoke,
Mass. Os = Savoy schist, probably Ordovician; do = granite of Carboniferous
age ; Ts •= Sugarloaf arkose ; Tg = Granby tuff ; Tb = Blackrock diabase ( intrusive) ;
Th= Holyoke diabase (extrusive), and Thp = Hampden diabase (extrusive), mem-
bers of the Newark series of the Triassic. (Emerson, U. S. Geol. Surv.)
are strike faults, each of such magnitude as to cause the repetition at
the surface in western New Jersey of all three divisions (Stockton,
FIG. 318. — Map showing the area where a sheet of igneous rock now appears at the
surface. The peculiarities of distribution are the result of faulting. (Hobbs
U. S. Geol. Surv.)
Lockatong, and Brunswick) of the Newark series (Fig. 321). These
1 Kiimmel, Jour. Geol., Vol. VII, pp. 23-52 — an excellent summary of the Newark
series of New York and New Jersey. More detailed descriptions of these faults, and
the structure of the New Jersey-Newark generally, are set forth by the same author
in the Annual Reports of the State Geologist of New Jersey for the years 1896 and
1897, and more briefly in the Journal of Geology, Vol. V, 1897, p. 541. Some of the
faults of the Newark in New Jersey had been earlier recognized by Cook, Smock,
Lewis, Darton, Russell, Lyman, and others, described elsewhere. See also New
York folio, U. S. Geol. Surv.
THE TRIASSIC PERIOD.
15
faults are continued into Pennsylvania.1 Of the numerous small
faults, few have a throw of more than 200 feet.
Of the southern areas, the Richmond area is best known.2 As
FIG. 319. — Map showing the surface distribution of a sheet of igneous rock in the
Pomperaug area of Connecticut. The peculiarities of surface arrangement are
due to faulting. (Hobbs, U. S, Geol. Surv.)
farther north, the beds here are much faulted and little folded (Fig.
322). The faulting is clearly shown by the surface distribution of
the series (Fig. 323). The trough-like basin which the Newark of
this area occupies, is thought to be the result of faulting rather than
of pre-Triassic topography. The Newark of this area contains a good
1 Lyman, Report on the New Red Rock of Bucks and Montgomery counties
(Pa.), State Geol. Surv., Final Rept., Vol. Ill, Pt. II.
2Shaler and Woodworth, 19th Ann. Rept. U. S. Geol. Surv., Pt. II.
16
GEOLOGY.
deal of igneous rock (diabase), mostly in the form of intrusive sheets
or sills. The coal, of which there are several beds in the lower part
FIG. 320. — Section across the Palisade Ridge and the Hudson River. /<7n=Fordham
gneiss, Pre-Cambrian ; €0s = Stockbridge dolomite, Cambrian-Ordovician; Tn=
Newark; Tp = Palisade diabase (intrusive). The surface of €0s near the center
of the section is below sea-level (Hudson River). The cliff to the left of €!Os is
the Palisade Ridge. (Darton, U. S. Geol. Surv.)
of the series, has sometimes been coked in the vicinity of the igneous
intrusions.1
FIG. 321. — Map showing the surface distribution of the several subdivisions of the
Newark series in New Jersey. The threefold outcrop of each principal division,
near the Delaware River, is shown. (Kiimmel, Geol. Surv. of New Jersey.)
In most of the area south of the New York- Virginia area, the dip of
the beds is to the northwest, though in one of the eastern patches it
1 For Trias of Maryland, see Md. Geol. Surv., Vol. I. For portions of the Triassic
in Va. and W. Va., see Harper's Ferry (Va.-Md.) and Monterey (Va.-W. Va.) folios.
THE TRIASSIC PERIOD. 17
is to the east, while still another appears to represent the bottom of an
old syncline. There is, on the whole, less evidence of disturbance at
the close of the Triassic period in this latitude than farther north.
The faulting is less, though by no means absent,1 and igneous rock
is less abundant or even wanting. The coal-beds, of considerable
thickness in this region, indicate conditions of stability during long
intervals of time.2
Thickness.— The thickness of the Newark series is variable and,
on account of the faulting, difficult of determination. In the Rich-
mond area of Virginia, the thickness is estimated at something more
than 3000 feet. In the areas farther south, the thickness is less, though
generally unmeasured. In New England, the thickness is estimated
VINITA TUCKAHOE CfiCEK
FIG. 322. — Structure of the Newark series on the James River, Richmond area, Va.
A A, minor flexures; //, faults. Structure of the deeper parts hypothetical. The
heavy black band represents coal. (Shaler and Woodworth, U. S. Geol. Surv.)
at 7000 to 10,000 feet, and in New Jersey 12,000 to 15,000 feet.
Undiscovered faults may exist which, by repeating beds, have led to
exaggerated estimates.
Correlation. — The structural relations of the Newark series in
the United States would not determine its age. The formations lie
unconformably on rock which is mainly pre-Cambrian, and they are
overlain unconformably by Cretaceous beds. About the Bay of
Fundy, however, the rocks lie unconformably on the Carboniferous
and early Permian. The physical relations of the Newark series there-
fore show that it is post-early-Permian, and pre-Cretaceous. Between
the Permian and the Cretaceous there are two periods, the Triassic and
the Jurassic. In the reference of the series to the former, the chief
reliance is usually placed on the fossils, and on the same basis the
series is believed to represent only the later part of the period.
There is another reason for believing the Newark series to be older
1 Keith, Harper's Ferry, Va.-Md.-W. Va. folio, U. S. Geol. Surv.
2 Glenn, Am. Geol., Vol. XXIII, pp. 375-9.
18
GEOLOGY.
than Jurassic. The physical relations of the -Newark beds to the
Cretaceous show that before the deposition of the latter, the former
had been uplifted, tilted, faulted, and subjected to a period of erosion
7T°40'
Newark System.
Diabase Coal Measures Vinita Group.
Dikes. and Lower sandstones
Barren Beds. and Shales.
Strike
and Dip.
Flat
Strata.
FIG. 323. — Map of the northern part of the Richmond area of the Triassic system, show-
ing the effect of faults on the outcrops of the several members of the series, and on
their relations to associated formations. (Shaler and Woodworth, U. S. Geol. Surv.)
sufficiently long to reduce the area where they occur essentially to
base-level. The time involved must have been very great, for the
hard trap, as well as the softer sedimentary formations, was brought
THE TRIASSIC PERIOD. 19
low. On physical grounds, therefore, there would be ample justifica-
tion for referring the Newark series to the earlier, rather than to the
FIG. 324. — Diagram showing structure of the Triassic beds and their relation to older
terranes, southeast of Harper's Ferry, in Virginia. Prc=Cacoctin schist, Protero-
zoic; €. Cambrian; Tn, Newark series, Triassic. (Keith, U. S. Geol. Surv.)
later part of the time-interval between the Permian and the Creta-
ceous.
Physiography of the Newark of New England and New Jersey.
The trap ridges of New England and New Jersey illustrate so clearly several
fundamental principles of physiography and structural geology, that a few points
in their history are here sketched.
Subsequent to its peneplanation in pre-Cretaceous or early Cretaceous time,
the area covered by Triassic beds was elevated, and a new cycle of erosion inau-
gurated. In this post-Cretaceous cycle of erosion, most of the sedimentary beds
were degraded readily, while the trap, being notably more resistant, withstood
erosion more effectively and came to stand out in conspicuous ridges. Many
of the prominent ridges in the Connecticut valley, including such elevations
as the Holyoke Range, Toket, Pond, Lamentation, and Farmington Mountains,
are simply the outcropping edges of trap sheets isolated by the removal of
the less resistant shale and sandstone. The Watchung Mountains of New Jersey,
and the Palisade Ridge along the lower Hudson, as well as many other elevations
of that and adjoining States, owe their origin to a similar sequence of events.
In New Jersey, the Lockatong formation, as well as the trap sheets, is a ridge-
maker.
That deformation other than tilting affected the Triassic system is shown
by numerous phenomena. Among these is the curvature of some of the trap
ridges, such as Cushetunk Mountain (Fig. 321), the rock of which is an extrusive
sheet of diabase. Since the general direction of dip of the Newark series in New
Jersey is to the northwest, the curvature means a syncline, the axis of which
is northwest and southeast. This folding probably accompanied the first de-
formation to which the Newark series was subject, rather than that which fol-
lowed the Cretaceous base-leveling, for the curved crest is approximately level.
The curvature of First and Second Mountains (Fig. 321) is probably to be explained
in the same way. The trap ridges of the Connecticut valley show similar phe-
nomena.
The trap outcrops of the Connecticut valley illustrate the manner in which
faulted strata of unequal hardness may come to express themselves topographic-
ally, and their study throws light both on structural and physiographic problems.
20
GEOLOGY.
A series of illustrations will make clear the problems involved; but to under-
stand them, it should be recalled that the general structure of the series is mono-
clinal, with the general dip to the east. If the dip were always to the east (or
in any constant direction), faults parallel to the strike (strike faults) would pro-
duce one series of phenomena, faults at right angles to the strike (dip faults,
CD, Fig. 325) would produce another series, and faults oblique to the strike
FIG. 325. FIG. 326.
FIG. 325. — Diagram showing the position of dip faults, oblique faults, etc. The
black band represents the outcrop of a layer of rock on a plane surface, and there-
fore the strike of the rock. AB= the direction of a strike fault, CD the direction
of a dip fault, and GH and EF directions of oblique faults.
FIG. 326. — Diagrammatic section showing dipping beds.
(GH and EF, Fig. 325) would produce still another (see also Vol. I, pp. 521
and 525).
1. Suppose a series of sedimentary beds with constant dip to the east to have
a single trap sheet, t, interbedded (Fig. 326). Suppose the series to be affected
by a strike fault with upthrow to the east. After erosion has cut down the up-
throw side to the level of the other, any layer (say the trap) will outcrop in two
parallel belts (t, Fig. 327). Had the upthrow been to the west (the dip being
east) a repetition might not have occurred, and the outcrop of a given layer,
such as the trap, might have been eliminated. If the faulted surface had been
reduced to the level of AB (Fig. 328), the trap sheet would not have appeared
at the surface.
2. Assume the same series of beds to be affected by a dip fault (outcrop of
fault plane along CD, Fig. 325) with the upthrow to the south. After erosion
has brought the upthrow side to the level of the other, the layer of trap will out-
crop in the manner shown in Fig. 329. If the upthrow had been to the north,
the result would have been as shown in Fig. 330; that is, in the case of a dip fault,
the outcrop of a layer on the upthrow side is (after erosion) shifted in the direc-
THE TRIASSIC PERIOD.
tion of dip. For a given throw, the horizontal shifting is greater, the
dip and the greater the amount of the degradation of the upthrow side.
21
the
FIG. 327. — Same as Fig. 326, after being faulted along the strike, and after planation.
The several layers are repeated at the surface.
3. Let the same series of beds be assumed to be affected by an oblique fault.
Let the plane of the fault be east-northeast by west-southwest (along GH, Fig.
325) and the upthrow on the south-southeast side. After erosion has reduced
the surface to a common level, the trap sheet will outcrop as shown in Fig. 331;
that is, the outcrop of the trap is offset with overlap. Had the upthrow been
to the north-northeast, the outcrop would have appeared as in Fig. 332; that
is, the outcrop of the trap would have been offset with a gap. Had the faulting
been along the line EF, Fig. 325, the result would have been illustrated by Fig.
333, in case of upthrow to the northeast.
4. If, instead of having a constant dip to the east the strata were slightly
deformed, that is, thrown into broad synclines and anticlines, the phenomena
FIG. 328. — Same as Fig. 326, after faulting with downthrow at the right. When
erosion has reduced the surface to A B certain strata, as t, fail to appear at the
surface.
would be slightly different. If such a series as the Newark, dipping to the east,
be affected by a broad syncline, any given layer, after base-leveling, will not
outcrop in a straight line, but in a curve (Fig. 334). If the deformation had
been an anticline instead of a syncline, the curve would have been in the oppo-
site direction ; that is, the outcrop curves away from the prevalent dip in the
22
GEOLOGY.
axis of a syncline and toward it in the axis of -an anticline,
the curvature of some of the trap ridges in New England.
This explains
FIG. 329.
FIG. 330.
FIG. 329. — Diagram illustrating the effect of a dip fault on outcrops where the struc-
ture is like that shown in Fig. 326, after the faulted surface has been reduced to
a plane. The south side was the upthrow side.
FIG. 330. — Same as Fig. 329, except that the opposite side is the upthrow side.
5. Where the deformed strata are affected by faults, the curved outcrops
maybe repeated in parallel positions (strike faults). They may be offset with-
FIG. 331.
FIG. 332.
PIG. 331. — Effect of an oblique fault on the outcrop of beds, where the structure before
faulting was that shown in Fig. 326. The south-southeast side was the up-
throw side, and the diagram represents the surface after it has been reduced to a
plane, subsequent to the faulting.
FIG. 332.-^-Same as the last, except that the fault was greater, and the north-north-
west side the upthrow side.
out gap or overlap (dip faults), or they may be offset with overlap or gap (oblique
faults).
Before base-leveling has been affected, but in an advanced stage of erosion,
each layer of resistant rock, such as the trap, constitutes a ridge. The ridge
THE TRIASSIC PERIOD.
23
is repeated or offset, with or without overlap or gap, according to the relation
of the direction of the fault plane to the dip and strike of the rock.
There is one condition under which an outcrop of the trap may be curved,
even when the strata are not deformed. If the surface be in that stage of erosion
where the trap constitutes a ridge, the outcrop of the trap will bend in the direc-
tion of dip wherever it is crossed by a valley; for here the ridge (outcrop) is
lower than elsewhere, and lowering the surface of a dipping stratum always
shifts its outcrop in the direction of dip.
All of the principles here set forth find illustration in the trap outcrops of
the Newark series of Connecticut. The faults which are supposed to explain
FIG. 333. FIG. 334.
FIG. 333. — Illustrates the effect of oblique faulting on outcrops. The more the
direction of the fault plane departs from the direction of dip, the greater the over-
lap (or if the opposite side had been the downthrow side, the greater the gap).
FIG. 334. — Diagram illustrating the effect of a gentle syncline, in beds of monoclinal
structure, on outcrop, when the surface is plane.
the relations of the trap outcrops to one another have not all been seen, but the
faulting is inferred from the relations of the trap sheets. Each outcrop of
trap does not therefore mean a separate flow of lava. Three principal sheets
of lava (all extrusive) seem to be represented by the many outcrops. Asso-
ciated with these there are minor ridges of intrusive trap. The faulting in the
Newark series of Connecticut has perhaps been most carefully worked out in
the small isolated area near Pomperaug. Fig. 318 shows the outcrops of one
bed of trap, and Fig. 319 that of another. In this small area, containing only
about fifteen square miles, the number of faults is said to be more than 250. l
Hobbs, 21st Ann. Kept. U. S. Geol. Surv., Pt. III.
24 GEOLOGY.
THE TRIASSIC IN THE WEST.
The deposits of the western interior.1 — When general sedimenta-
tion ceased in the eastern half of the United States near the close of
the Paleozoic era, a tract along the Pacific coast probably remained
beneath the sea, while another great area in the western interior, but
partially and temporarily connected with the sea, became the site
of varied sedimentation. Between the ocean on the west and this
interior area of sedimentation, there seems to have been an elongate
area of land which, including much of Mexico on the south, stretched
north through western Arizona, eastern Nevada, western Utah,
eastern Idaho, and western Montana, to British Columbia. In the
United States, the interior area of sedimentation was chiefly between
the 100th and the 113th meridians. Its southern limit, so far as now
known, was not far from the southern boundary of the United States,
while at the north it extended somewhat into Canada. This area
of sedimentation is believed to have been cut off from the Gulf by
a considerable land area in eastern Texas. If it had connection with
the sea at all, as is very doubtful, it was probably slight, and with
the Pacific Ocean north of the boundary of the United States. Into
this interior area of sedimentation, which perhaps did not depart
widely from the area of Permian sedimentation, detritus was borne
from the surrounding lands. Some of the deposits were probably
laid down subaerially by streams, some in fresh-water lakes, and some
in bodies of salt water, as in the Permian period. The structure of
some of the sandstone is such as to suggest strongly an eolian origin.
The deposits of the period are in large measure concealed by later
beds, but are exposed at various points where the strata have been
elevated, and the overlying beds removed by erosion. The most
easterly outcrops of the system are found in Texas,2 Indian Territory,3
and South Dakota. The Triassic system may underlie the later for-
mations west of these localities, and between them and the Rockies.
1 There is some doubt about the age of most of the beds formerly referred to this
system. The tendency of later study has been to refer more and more of them to
the Permian. See references under Permian, and Hill, Physical Geography of the
Texas Region, folio U. S. Geol. Surv.
2 See last foot-note.
3 Gould, Univ. of Kansas Quarterly.
THE TRIASS1C PERIOD. 25
Throughout most of this area, the Triassic beds are red, and in the
absence of fossils, and of structural unconformity, are not readily differ-
entiated from the Permian below.1
In Texas the beds generally regarded as Triassic underlie the
" Staked plains " of the western part of the State, and outcrop along
FIG. 335. — Triassic sandstone five miles south of Lander, Wyo., showing characteristic
cross-bedding. (Branson.)
their eastern base. The deposits of this locality show that the water
in which they were laid down was shallow and fresh, and the belief
is that the sediments entered it from the east.2
In the Black Hills of South Dakota 3 unfossiliferous, gypsiferous
beds (Spearfish) which are believed to be Triassic overlie the Permian
conformably,4 and underlie the Jurassic unconformably. The rela-
tions of the Triassic to the Permian and Carboniferous indicate that
though the interruption of sedimentation at the close of the Paleozoic
era was by no means complete in this part of the continent, the marine
sedimentation of the earlier era gave place to salt-lake sedimentation
in the later.
A series of nearly unfossiliferous strata, among which are many
" Red beds " occupying the stratigraphical position of the Triassic
system, outcrop interruptedly along the eastern base of the Rockies
from British America to New Mexico. These beds are thin, and nearly
everywhere contain more or less gypsum and sometimes salt. Occa-
1 The Red Beds of Kansas, formerly thought to be Triassic in part, are probably
all Permian (Williston). The opposite view is advocated by Prosser, University of
Kansas Geol. Surv., Vol. II.
2 Geol. Surv. of Texas, 1896, pp. 227-234.
3 Newton, Geol. of the Black Hills, U. S. Geol. Surv.
4Darton, 21st Ann. Kept. U. S. Geol. Surv. Also Qelrichs and Edgemont,
S. D.-Neb., New Castle, Wyo.-S. D., and Hartville, Wyo., folios, U. S. Geol. Surv.
26 GEOLOGY.
sionally they contain fossil leaves of types which seem to ally the beds
with the Trias of the east. In Wyoming, the Triassic beds, because
of their high color and unique mode of erosion, are the most conspicuous
formations of the State.1 The Triassic beds of this region are not
always readily distinguished from the Permian on the one hand, and
from the Jurassic on the other. So difficult is the separation, that
the Trias and Juras of this region are often grouped under the name
Jura-Trias. Triassic beds have, however, been identified by means
of fossils, in the Wind River region of Wyoming, where the fossil-bearing
beds are 550 feet above the base of the Red Beds and 250 feet below
the top.2 The upper part of the Red Beds in this region is gypsiferous.
Triassic beds have also been recognized in southern Wyoming by their
vertebrate fossils.
Farther west, so far as the country has been carefully studied,
Red beds have frequent representation among the surface rocks, but
the outcrops are usually confined to narrow belts about the moun-
tains where uplift and subsequent erosion have exposed the edges of the
strata, or in valleys excavated through younger formations. Through-
out all this region, red sandstones and shales make up a notable part
of the Triassic system. Conglomerates are present locally, and gyp-
sum is a common accompaniment of the clastic beds over most but
not over all of the area.3
In southwestern Colorado, and in the adjacent part of New Mexico,
some of the Triassic deposits seem to have been made in fresh water.4
The fresh-water beds here and in Texas, and the salt-lake deposits
over many other parts of the inland region, suggest that the Triassic
sediments of different localities were laid down in separate basins.
In much of this western interior region the undifferentiated Triassic
and Permian rest conformably on the Carboniferous (Pennsylvanian),
though occasionally, as in some parts of Wyoming, they overlap it
and rest upon pre-Cambrian formations. Where non-fossiliferous Red
1 Knight, Bull. 45, Wyoming Exp. Station, p. 133.
* Williston and Branson, unpublished data.
3 For details, see the following folios of the U. S. Geol. Surv.: Ten Mile, Anthracite
and Crested Butte, Telluride, Walsenburg, Pike's Peak, La Plata, and Pueblo, Colo.;
Fort Benton, Little Belt, Livingston, and Three Forks, Mont.; Yellowstone Park,
Wyo.; also Gilbert, 17th Ann. Kept. U. S. Geol. Surv., Pt. II, p. 560; and Knight,
Bull. 45, Wyo. Exp. Station.
4 Dolores formation, Telluride folio, U. S. Geol. Surv.
THE TRIASSIC PERIOD. 27
Beds rest on the Pennsylvania!! conformably, at least the lower portion
of the former should probably be assigned to the Permian. In south-
western Colorado and eastern Utah, the Trias rests unconformably on
older, deformed, unfossiliferous Red Beds, and on strata of Pennsyl-
vanian age, and perhaps overlaps even older formations.1
Thickness. — In the eastern part of the inland basin, the Triassic
system is thin, sometimes no more than 100 feet. To the west it
thickens, reaching to 2000 to 2500 feet in the Uinta Mountains, beyond
which it again thins and becomes conglomeratic in western Utah.
It is on the basis of these characteristics, as well as because of the
absence of the system over western Utah and eastern Nevada, that the
western limit of the interior basin is believed to have been in the longi-
tude of Great Salt Lake. No general subdivisions of the system have
been adopted for this region.
The Triassic system on the Pacific slope.2 — In the latitude of Nevada,
the Pacific seems to have extended eastward over the site of the Sierras
to longitude 117° (approximately), as shown by the distribution of
the marine Triassic strata. The shore line of the Pacific farther north
has not been definitely located. It was probably irregular, and, in
general, several degrees farther east than now, well up into British
Columbia. Still farther north, between 55° and 60°, the sea is believed
to have crossed the entire Cordilleran 3 belt, though this northern bay
east of the Rockies was probably not connected freely with the areas
of sedimentation in the western interior.
It is along the Pacific coast that the Triassic system in America
has its greatest development. In the United States, the sediments
of this part of the system appear to have been derived from the newly
uplifted lands to the east. The published measurements assign the sys-
tem the great thickness of 17,000 feet (maximum) hi the West Hum-
boldt range of Nevada,4 wiiere it rests on pre-Cambrian terranes. To
1 Cross & Howe. The unconformity is seen near Ouray, in the Uncompahgre
valley, and above Moab, on Grand River. Bull. G. S. A., Vol. XVI, p. 447.
2 King, Geol. Surv. of the 40th Parallel, Vol. I. An account of the Triassic
as far west as the Sierras in this latitude. See also the following folios, U. S. Geol.
Surv. : Bidwell Bar, Colfax, Downieville, Jackson, Lassen's Peak, Maryville, Mother
Lode, Nevada City, Pyramid Peak, San Luis, Sonora, and Truckee, Cal., and Rose-
burg, Ore.
8 Dawson, Science, March 15, 1901.
4 King, loc. cit. ,
28 GEOLOGY.
have supplied such a volume of sediment, the land to the east must
have been high, or repeatedly renewed, to counterbalance the waste,
unless the high measurement of thickness be due to oblique deposition.
In the western region, where the system has its greatest thickness,
two principal divisions have been recognized, viz., the Koipeto below
(4000 to 6000 feet thick), and the Star Peak above "(10,000 feet). The
lower of these series consists of siliceous and argillaceous beds, and
the upper of sandstone, quartzite, and limestone. In the mountains,
such as the West Humboldt range of Nevada, the system, especially
the lower part of it, is highly metamorphic, and more or less affected
by irruptive rocks.
Farther west, Triassic rocks, now upturned and eroded, are exposed
near the summit of the Sierras l in northern California (Plumas County),
and at various points northward to Alaska. Recently an extensive
series of marine Triassic beds has been identified in the Eagle Creek
Mountains of northeastern Oregon,2 and in the Snake River canyon
between Oregon and Idaho. In the northern part of the United
States, the Triassic beds, if as wide-spread as the above occurrence
suggests, are largely concealed by igneous rocks and by sedimentary
beds of lesser age.3 West of the Gold Range in British Columbia,
Triassic formations (Nicola), largely igneous, are wide-spread and
thick (13,500 feet). Locally, at least, the system is unconformable on
the Carboniferous.4 The igneous intrusions are thought to be largely
submarine.5 The Triassic is also known in Vancouver and Queen
Charlotte Islands. Igneous formations of Triassic age are thought
to be wide-spread in southeastern Alaska.6
Though most of Mexico appears to have been land during the Tri-
assic era, there were within its area (Sonora) inclosed bodies of water;
as in the United States. The estuary or inland-sea phase of the for-
mation also appears in Central America.
The succession of faunas in the Trias of the Pacific coast indicates
1 Geol. Surv. of California.
» Lindgren, Sci., Vol. XIII, N. S., 1901, p. 270.
3 For details of the Trias (Jura-Trias) on the Pacific coast, see the following folios
of the U. S. Geol. Surv.: Truckee, Bidwell Bar, Jackson, Lassen's Peak, Pyramid
Peak, Mother Lode, and Sonora, Cal., and Roseburg, Ore.
4 Dawson, Bull. Geol. Soc. of Am., Vol. XII, p. 72.
'Dawson, Science, Mar. 15, 1901.
6 Brooks, Bull. Geol. Soc. of Am., Vol. XIII, pp. 260-3.
THE TRIASSIC PERIOD. 29
that considerable changes in the physical geography of the northern
Pacific were in progress during the period. In the early Trias, the
waters of the Pacific coast seem to have been in such connection with
those of the Indian and Arctic oceans that animal life was able to
migrate back and forth 1 between these various regions, and the tem-
perature seems to have allowed much wider migrations in latitude
than are now common. In the Middle and Upper Trias there seems
to have been faunal connection with the Mediterranean region, per-
haps by way of the Indian Ocean.
CLIMATIC CONDITIONS.
The character of the conglomerates in some parts of the Triassic
system has been made the basis of an argument for a cold climate
during the Triassic period; but although the coarseness and litho-
logic character of the conglomerate are quite sufficient to suggest
glaciation, they do not prove it, and the few fossils found do not bear
out the suggestion.
Some of the peculiarities of the conglomerate might be explained
if the climate were arid. In such climates, the expansion and con-
traction due to changes of temperature are so great as to be very effec-
tive in disrupting rock if its surface is not covered by soil or other
debris. Under such circumstances, much coarse debris originates,
largely of rock which is undecomposed. Violent storms (cloudbursts) r
which often characterize arid climates, might account for the trans-
portation of debris from the place of its origin to the place of its depo-
sition. For the formation of abundant debris in this way, steep slopes
are needful, for gentle slopes and flats soon get a covering of soil or
mantle rock which prevents the disruption of the rock beneath. If
this were the origin of the coarse materials of the conglomerate, their
rounding and wear would have to be attributed to the waves of the
body of water in which deposition took place. The wide distribu-
tion of gypsum and salt in the Triassic system, not only of America
but of Europe, is a positive argument for wide-spread aridity.
CLOSE OF THE TRIAS.
Considerable geographic changes marked the close of the Triassic
period in eastern North America, especially to the north, bringing
1 Smith, Jour. GeoL, Vol. Ill, p. 375.
30 GEOLOGY.
the areas which had been the sites of deposition to a higher level, fault-
ing the rocks, and affecting them by igneous intrusions. These changes
were comparable in extent and importance to the changes which sepa-
rate various systems of the Paleozoic series, but they were not of con-
tinental dimensions. The rocks of the next system are not repre-
sented north of Maryland, and perhaps nowhere in the Atlantic and
Gulf plains. In the western part of the United States, there seem
to have been no physical changes of great moment separating the
Triassic from the Jurassic, and the sedimentary history of much of
that part of the continent seems to have run an uninterrupted course
from the beginning of the first of these periods to the later part of
the second. The case may have been somewhat different north of
the United States, for in British Columbia and in the adjacent islands,
Triassic and older formations were upturned, deeply eroded, and
again submerged before the beginning of the Cretaceous. The great
igneous formations associated with the Trias of the northwest appear
to have been made during the Triassic period, rather than at its
close. The greatest body of igneous rock referred to this period, the
great batholith of the Coast Range, is nearly 1000 miles long.1
FOREIGN TRIASSIC.
Europe.
The Triassic formations of Europe are found in widely separated
localities. The largest exposed area is in northeastern Russia, but
the system is much better known in some other parts of the continent,
especially in Germany and England. It is also known in most of
the southern countries, though its outcropping areas are relatively
small. In England, the system is unconformable on the Permian
and older beds, thus showing that sedimentation was interrupted
after the Permian period. On the continent, on the other hand, the
Triassic system is generally conformable on the Permian.
The Triassic system of Europe has two somewhat distinct phases,
known as the Triassic (largely non-marine) and the Alpine (marine)
phases, repectively. The Triassic phase of the system is developed
with more or less modification throughout the northern part of the
1 Dawson, Geol. Soc. of Am., Vol. XII, p. 89, and Brooks, Geol. Soc. of Am., Vol.
XIII, p. 260.
THE TRIASSIC PERIOD.
31
continent, while the Alpine phase characterizes the southern part.
Physically, the non-marine phase of the system resembles the Per-
mian of Europe, and the Permian and Triassic of the United States
east of the Pacific slope.
In general, the Upper Trias is more wide-spread than the Lower,
FIG. 336. — Sketch-map of Europe showing areas of sedimentation in the early part
of the Triassic period. The broken lines represent areas of non-marine deposits;
the full lines, areas of marine deposits. (After De Lapparent.)
especially in the southern part of the continent, and is marine over
a wider area.
The following table gives the principal divisions recognized in
Britain and Germany:
Britain.
Rhsetic, 150 ft. max.
Upper Trias., 3250 ft. max.
Lower Trias., 2000 ft. max.
Germany.
Keuper, 820-2000 ft.
Muschelkalk, 820-1100 ft.
Bunter, 650-1800 ft.
Germany. — In Germany, where the Triassic phase of the system
was first exhaustively studied, and where it has its typical develop-
32 GEOLOGY.
merit, it is made up of three principal divisions. The oldest (Bunter)
and youngest (Keuper) divisions consist of beds of fragmental rock,
including conglomerates, sandstones, and shales, separated by a for-
mation (Muschelkalk) of limestone. The oldest of these formations
was deposited chiefly in lakes, inland seas, and on the dry land, as
shown by the fossils, the beds of salt and gypsum, and the dune struc-
ture of the sandstone.1 There are in some places cubes of sandstone,
the sand of which appears to have been originally included in crystals
of salt, as that mineral was precipitated from solution in inclosed
bodies of water. Subsequently the salt was dissolved, but replaced by
other cementing matter which preserved the cubes of sandstone.
Toward the upper part of the formation, thin beds of marine origin
are locally intercalated with those of non-marine origin, showing that
changes in the relation of land and water were in progress, and that
the sea gained on the land to some extent toward the close of the
epoch. Tracks of land reptiles are sometimes found on the layers
of shale and sandstone, showing that they were deposited on land
or in water sufficiently shallow to allow terrestrial animals to wade
in it. The tracks sometimes occur in layers which had been cracked by
drying at the time the tracks were made. This shows that the mud-
beds over which the reptiles walked were sometimes dry, and that
for periods sufficiently long to let the cracks develop. The areas
where these phenomena occur may have been under water during
wet seasons, and dry at other times.
The tracts where this formation comes to the surface are, on the
whole, not fertile, and have been allowed to remain in forests
extensively. So true is this, that the Bunter sandstone may be said
to be the " forest formation" of western Germany. The name (Bunter)
has reference to the brilliant colors displayed by the formation. Red
predominates, but other colors are not absent. The Bunter sand-
stone of the Eifel carries galena in small grains and lumps, and the
Romans mined it.2
The second formation, the Muschelkalk, shows that the encroach-
ment of the sea recorded by the upper part of the preceding formation
had gone so far that the ocean held sway over much of the area where
1 Kayser, Geologische Formationskunde, p. 330.
2 Ibid., p. 283.
THE TRIASSIC PERIOD.
33
it had been absent formerly. The Muschelkalk fauna has been thought
to indicate that the sea in which it lived was not the open ocean,
but rather a body of water comparable to the Black Sea or the Baltic.1
As the name indicates, limestone makes up the larger part of the
formation.
The third formation, the Keuper, resembles the first, and, like it,
is marine in its upper portion, and is followed by the marine beds of
FIG. 337.— Sketch-map of Europe, indicating the areas of sedimentation during the
late Triassic. The broken lines represent areas of non-marine deposition; the
full lines, areas of marine deposits. (After De Lapparent.)
the Jurassic period. The Keuper contains a little coal (not workable),
a common accompaniment of shallow-water and marsh formations.
England. — The chief point of difference between the Trias of Ger-
many and that of England lies in the fact that the marine member
of the former is absent from the latter. Otherwise the system cor-
responds in the two countries, so far as general characters are
concerned. The absence of the marine division from the system in
1 Kayser, op. cit., p. 286.
34 GEOLOGY.
England shows that the sea which overspread Germany did not cover
England, and the conformity of the Upper Trias with the Lower in
the latter country leads to the inference that the time equivalent of
the Muschelkalk is included in one or both of these divisions. The
uppermost (marine) division of the system in England (the Rhsetic)
corresponds in a general way with the upper part of the Keuper (also
marine) in Germany.
In the two countries the Triassic system has the following points
in common: (1) The dominant color is red; in England, indeed, the
system is commonly known as the New Red Sandstone system, though
the Permian was formerly included under this term; (2) in both countries
the formations are poor in fossils; (3) in both, gypsum and salt are
present. In England the salt occurs in workable, lens-shaped beds,
sometimes 200 or 300 feet in thickness. The gypsum, in the white
amorphous form of alabaster, also occurs in workable quantity in
some parts of England. (4) In both countries, the strata bear abun-
dant marks of shallow-water or subaerial origin, such as footprints of
land animals, cross-bedding, and rapid changes laterally in the com-
position of the beds.
The Upper Trias of England is rather remarkable for containing
a large amount of dolomitic conglomerate. This, as will be remem-
bered, is locally one of the characteristics of the Newark series in the
eastern part of the United States. In England, however, the origin
of the conglomerate presents no serious problem, for it lies against the
limestone cliffs from which its materials were derived.
Sweden and Russia. — In southern Sweden, where the Trias has
slight representation, it contains coal, showing that the same general
conditions (shallow lakes, marshes, etc.) prevailed in the north as in
the rest of western Europe. The Trias of Sweden was probably once
continuous with that of Germany, and may still be, for borings have
shown that it underlies various parts of the North German lowland.
The Trias of most of Russia consists of highly-colored beds (mainly
red) which are poor in fossils. They appear to belong to the non-
marine phase of the system. No contemporaneous igneous rocks are
known in the Triassic phase of the system.
The character and the distribution of the Triassic beds of northern
and western Europe have led to the inference that the Triassic beds
of Britain were accumulated in great inland basins which
THE TRIASSIC PERIOD. 35
"covered a large part of England, and seem to have extended north into
southern Scotland and across the area of the Irish Sea into the northeast coast
of Ireland. It is possible also that the same sea stretched across what is now
the English Channel into northern France. Another lake is indicated by the
red sandstones of Elgin (northeastern Scotland). The lands surrounding these
lakes were clothed with cypress like evergreens, and their shores were frequented
by the labyrinthodonts and various reptiles — the highest forms of vertebrate
life being represented by small marsupials. The briny waters were unfavorable
to life, and we have consequently but little trace of any aquatic fauna. . . .
Eventually the lacustrine areas became largely silted up, and then subsidence
of the land took place, so that the sea invaded the area and occupied some of
the shallow depressions. In these marine areas the Rhsetic deposits accumu-
lated.
" On the continent, the evidence supplied by the German Trias shows that
during a large part of the period an extensive inland sea extended westwards
from Thuringerwald across the Vosges into France, and stretched northwards
from the confines of Switzerland over what are now the low grounds of Holland
and northern Germany. In this ancient sea, the Harz Mountains formed a rocky
island. In the earlier stages of the period the conditions seem to have been
much the same as in the English area, but the thick Muschelkalk, with its num-
erous marine forms, seems to indicate an influx of water from the open sea.
Afterwards, however, this connection was closed, and the subsequent accumula-
tions point to an increasing salinity, during which depositions of gypsum, rock-
salt, etc., took place, while the marine fauna disappeared. Towards the close
of the period, after the great lake had been largely silted up, a partial influx
of the sea took place, when deposits containing a fauna comparable to that of
the English Rhsetic were laid down in some areas."1
This citation perhaps fails to recognize adequately the probable
subaerial origin of some parts of the Triassic system.
Southern Europe. — In contrast with the Triassic phase of the
system, the alpine or marine phase, which has its best development
in the eastern and southern Alps, is made up of thick beds of lime-
stone (often dolomitic), alternating with thinner beds of clastic rock.
The limestone and dolomite are much more resistant than the asso-
ciated shales, and as a result, erosion has developed a striking topog-
raphy at several points in the Triassic terranes of the southern Alps
— a topography so striking that the localities where it is seen have
become the objective point of travel, not only for geologists, but for
lovers of wild and picturesque scenery. In these regions the dolo-
mite (limestone) stands up in bare, bold-faced walls, peaks, and towers,
1 James Geikie, Outlines of Geology, pp. 311-312.
36 GEOLOGY.
surrounded and separated by valleys and passes clothed with abundant
vegetation. The decay of the projecting limestone leaves little soil
behind, since most of the rock is soluble, and the little which is formed
is promptly carried away by wind and rain.
In the eastern Alpine region there are large and more or less indi-
vidual bodies or " "reefs" of dolomite, and sometimes of limestone,
which possesses exceptional characteristics. They are essentially
without stratification, are poor in fossils, have steep slopes, and a
superficial bedding concentric with the surface. As the steep slopes
suggest, these reefs wedge out rapidly on some or all sides. These
bodies of dolomite (or limestone) attain great thicknesses, and are
associated sometimes with thinner beds of stratified limestone or
dolomite of a composition like their own, and sometimes with beds
of clastic rock which fit up against them on some or all sides. From
the reefs, there are often projections of dolomite extending out into
the clay-beds surrounding.
In spite of the difficulties involved in the explanation, it is very
generally believed that the so-called reefs are really such, and probably
of coral origin. The absence of abundant fossil corals in them seems
at first a difficulty; but corals are the most abundant fossils found,
and the absence of recognizable coral structure in the body of some
modern coral reefs is well known. Coral is one of the most soluble
forms of CaC03, and is therefore more readily subject to change than
most other organic deposits of this substance. Coral reefs are known
to possess the superficial concentric stratification which character-
izes these reefs, and to possess similar lateral projections. On the
whole, the structure of the dolomite reefs seems more readily explained
on the coral reef hypothesis than on any other. In the making of the
limestone of the alpine phases of the system, marine algae appear to
have played an important part, and even the reefs have been ascribed
to them.
The Trias of the Italian Alps is the source of the Carrara marble.
The Trias of the western Alps is largely non-marine. In some parts
of Switzerland, the Upper Trias contains coal, and contemporaneous
igneous rocks enter into the same division of the system.
The marine phase of the system shows that the physical conditions
which obtained in southern Europe, where there was an open sea, were
notably unlike those of western and northwestern parts of the continent
THE TRIASSIC PERIOD. 37
at the same time. This is in keeping with the physical conditions
which existed in the continent almost uninterruptedly after the begin-
ning of the Paleozoic era. Near the close of the Trias (RhaBtic), the
differences between the eastern and southern Alps on the one hand,
and northern and western Europe on the other, became much less
distinctly marked.
The marine phase of the system reaches its greatest thickness
(about 13,000 feet) in the southern Alps, where the deposits are
thought to have been made in a great geosyncline, and the beds were
subsequently made into mountains as in the case of the Appalachians.
The non-marine formations of red color so characteristic of the
system both in North America and Europe afford another striking
inter-continental analogy.
Asia. — The marine phase of the system found at various points
south of the Alps is continued eastward through the Carpathian and
Balkan Mountains to Asia, where it is found in Asia Minor, in the
Himalayas, the Salt Range, and still farther east. The Trias of
Afghanistan is partly non-marine, and contains some coal. The Trias
of the Deccan also is non-marine, and constitutes the upper part of
the great Gondwdna system, of which the lower parts (Talchir, etc.,)
are Carboniferous or Permian.
The Marine Trias is also found in the high latitudes of Asia and
Europe, including Japan, eastern Siberia, and numerous islands north
of Eurasia (Spitzbergen, Bear Island, the New Siberian Islands, etc.).
In Asia the Trias is generally conformable above the Permian, and
beneath the Jurassic. The relations of the Permian in India suggest
that the great changes marking the transition from the Paleozoic to
the Mesozoic occurred at the close of the Carboniferous, or during
the Permian, rather than at the close of the latter.
South America. — In South America no marine deposits of Triassic
age are known east of the Andes, from which it is inferred that this
part of the continent was out of the sea. Non-marine Triassic beds
are known in Argentina and Chili, where they are coal-bearing.1 Marine
Triassic beds are known at various points in the Andes, in such positions
as to show that the site of parts of this great system of mountains
was at this time beneath the sea.
1 Kayser, op. cit., p. 308.
38 GEOLOGY.
Africa and Australia. — The Triassic system seems to be present
in South Africa (Karoo sandstone), in Australia (Hawkesbury sand-
stone of New South Wales), and in New Zealand and New Caledonia.
In New Zealand, it contains coarse conglomerate.
General provinces. — Reviewing the Triassic system of all coun-
tries, Kayser 1 recognizes five provinces of the marine part of the
system. There are (1) the Mediterranean province, (2) the southern
Asiatic province, (3) the Paleo-arctic province, (4) the American (western
North and South America) province, and (5) the Australian province.
This grouping is based largely on faunal characteristics. The first
and second provinces have some species and many genera in common,
while the fourth has some likeness with the first, second, and third.
THE LIFE OF THE TRIASSIC PERIOD.
Those remarkable physical conditions that had. dominated the
land and impoverished its fauna and flora in the Permian period still
held sway during the earlier part of the Triassic. In their general
biological aspects, as in their physical, the two periods were akin, if
not really parts of one great land period. Toward the close of the
Triassic there was a pronounced change, attended by a physical and
biological transition toward the Jurassic stage, in which lower levels
and greater sea encroachment prevailed, with corresponding life phases.
Nearly all that is known of North American Triassic life belongs to
this later portion of the period.
The Plant Life.
The record of the vegetation is very imperfect. The vegetation
was probably scant in reality, for broad saline basins and arid tracts
imply conditions inhospitable to plant life. An environment that
could give rise so generally to coarse red sandstones and conglomer-
ates— even limestone conglomerates — could not well be congenial to
luxuriant vegetation.
The dominance of the gymnosperms. — The Triassic was distinctly
an age of gymnosperms the world over; the supremacy of the pteri-
dophytes had ceased, though ferns, true to their persistent nature,
still held an important place, and the equisetales were a more vital
1 Geologische Formationskunde, pp. 327-329.
THE TRIASSIC PERIOD. 39
factor than now. The great lycopods were almost gone, the last of
the sigillarias being among the lingering representatives. Among the
gymnosperms, the cordaites were already far down their decline towards
extinction, but conifers of the types that had come in during the Per-
mian, and kindred new ones, were prominent, while the cycadean group
was still in a stage of deployment and occupied the central place of
interest. Very much as the ferns in the Carboniferous period were
deployed into transition forms (Cycadofilices) , so now the cycadeans
had a divergent branch, the Bennettitales, which until recently were
classed simply as cycads. The cycads have heretofore been regarded
as embracing three groups, the Cycadece, now typified by the Cycas
of the eastern hemisphere, the Zamiece similarly typified by the living
Zamia of the western hemisphere, and the Bennettitece, a wholly extinct
family supposed to be true ancestral cycads; but recent investigations
have shown that the last differ from the others so much in structure
and mode of fruiting as to require their recognition as a divergent
type. While this divergence is universally recognized, some paleo-
botanists conservatively leave the group in the class Cycadales, under
the name Bennettitece, while others make it a separate class, Ben-
nettitales.1 It is at any rate cycadean in the broad sense of the term.
Besides many structural peculiarities which cannot be noted
here, the seed of the Bennettitales had certain angiospermous features.
Suggestive as this fact is, it is not to be inferred that the Ben-
nettitales were the ancestors of the angiosperms, for this is regarded
as improbable. In many cases the imperfect relics of Triassic species
do not afford the criteria for distinguishing between the Bennettitales
and the Cycadales, and such forms can only be spoken of as cycadeans.
It is probable that the majority of the known species were bennetti-
talian, but the true cycad branch was probably represented. Among
the genera referable to the group were Zamites (Fig. 338, e, /), Otoza-
mites (Fig. 338, i), Podozamites (Fig. 338, /), Pterophyllum, Ctenophyl-
lum, and Cycadeomyelon, the last, at least, identified as bennettitalian.
The Triassic conifers bore the scrawny aspect of the walchias and
voltzias of the Permian. They deployed into many new genera of
like types, such as Palissya (Fig. 338, a), Brachyphyllum (Fig. 338, c),
1 Scott, Studies in Fossil Botany, 1900, pp. 445-475; Coulter, Seed Plants, 1901,
pp. 142-150; Ward, Older Mesozoic Floras of U. S., 20th Ann. Rep. U. S. Geol. Surv.,
II, pp. 242-248, 1898-1899.
40 GEOLOGY.
Cheirolepis (Fig. 338, b), Albertia, and Ullmania. The ginkgos were
represented by Baiera. It does not appear from the record that any
of these gymnosperms were especially large, but on the contrary rather
dwarfish, the conifers bearing the aspects now found on sandy barrens
and arid tracts. The calamites had given place to true equiseta,
which were represented by forms that were gigantic in comparison
with modern types. In the far east and in the southern hemisphere,
the Glossopteris and its allies constituted a marked feature of a flora
whose general aspect was much like that of the preceding Permian
in that quarter. The Triassic floras of Europe and America, so far
as known, were much alike and bore a scrawny pauperitic aspect that
reflected the hostile conditions against which they struggled, condi-
tions for which the stunted conifers of to-day stand as representatives.
In the closing stages of the period, the Rhsetic epoch and its equiva-
lents, there seems to have been much amelioration of the previous
hostile conditions and a much ampler development of the flora. The
larger part of the known American fossils belong to this stage. In
favored portions of the Newark series from Connecticut to North
Carolina, plant remains occur, and in the coal-beds of the latter state
and of Virginia, the flora is more amply represented. The Richmond
coal-beds are regarded by Fontaine 1 as the product of marsh vegeta-
tion accumulating where it grew, while the Carolinian deposit shows
more evidence of in wash, and represents the vegetation of the adjacent
country. The habitats represented by the fossils of the more northerly
states are less clear, but it is doubtful whether any represent the typical
upland-inland vegetation.2 The coal-beds of Virginia contain immense
numbers of equiseta and ferns, but almost no conifers and but few
cycadeans; the North Carolina deposits, comparatively few ferns, but
many conifers and cycadeans. As this distribution implies that the
conifers were not marsh plants, the .pseudoxerophytic peculiarities
of such plants cannot be appealed to in explanation of the markedly
xerophytic aspect of the Triassic conifers, as was done in the case
1 Mon. VI, U. S. Geol. Surv., 1883.
2 The older Mesozoic plants of this region have been made the subject of a special
memoir by Fontaine, Mon. VI, U. S. Geol. Surv., 1883; those of New Jersey and
Connecticut by Newberry, Mon. XIV, U. S. Geol. Surv.; and all have been sum-
marized by Ward, Twentieth Ann. Kept. U. S. Geol. Surv., Pt. II, 1898-99, in which
there is reference to all previous writers, and quotations from the valuable paper of
Wanner.
THE TRIASSIC PERIOD.
41
ha
of the Carboniferous trees. The group figure (Fig. 338) embraces
characteristic forms from the Newark formation. A few plant fossils
,ve been recovered from New Mexico, Arizona, and California (Taylors-
FIG. 338. — A GROUP OF TRIASSIC GYMNOSPERMS FROM THE ATLANTIC COAST. CONIFERS:
a, Palissya sphenolepis Brong., a form closely allied to Walchia; b, Cheirolepis
muensteri Schimp.; c, Brachyphyllum yorkense Font.; d, Schizolepis liaso-keu-
perinus Braun. CYCADEANS: e, Zamites yorkensis Font.; /, Zamites pennsylvanicus
Font.; g, Cycadeospermum Wanneri Font.; h, Cycadeoida emmonsi Font.; i, Oto-
zamites carolinensis Font.; /, Podozamites tenuistriatus Font.
ville). Limited coal deposits were formed in Germany and Scandi-
navia, from the latter of which 150 species of plants have been recovered.1
The Land Animals.
All evidences point to complete continuity between the Permian
and Triassic land animals. The vicissitudes of shifting aridity and
other changeable conditions seem to have markedly affected both
periods, but not to have put barriers between them; rather to have
made adaptation to the one a fitting preparation for continued
evolution in the other. The record probably does not show, however,
the land animals most affected by the vicissitudes of the Permian
and Triassic climates, but rather those which frequented the water-
1 For general treatment of Triassic plants see Zeiler's and Potonie's treatises, pre-
viously referred to.
42 GEOLOGY.
borders and the adjacent lowlands where ' alone relics were usually
preserved by sedimentation.
Though the amphibians had lost the foremost place in the Permian,
they still formed a notable element in the European and American
Triassic faunas. More than twenty-two genera have been described,
all belonging to the Temnospondyli and Stereospondyli, or true laby-
rinthodonts. During the period, however, they entered upon a rapid
decline, and by its close had ceased to be a prominent feature of the
land life, a decline from which they have never recovered. Ancestors
of the whole tribe of terrestrial vertebrates, they soon became its most
insignificant representatives. None of the modern amphibians had
yet appeared.
The strange ancestral reptiles rapidly evolved into higher forms.
The branch with the mammalian strain (Synapsida) seems to have
been left far behind by the more distinctively reptilian branch
(Diapsida). The latter developed prodigiously in the closing stages
of the period, when the conditions were ameliorated and vegetation
began again to flourish and furnish a better basis for animal life. Every
chief group of reptiles had its representatives before the close of the
FIG. 339. — Oudenodon trigoniceps. An anamodont (or Dicynodont) from the Karoo
formation of South Africa, so similar to forms of the Trias in Wyoming as to be
distinguished from them with difficulty. (After Broom.)
period, Rhynchocephalia (including the Proterosauria and Gnathosauria) ,
Crocodilia (including Phytosauria) , Thalattosauria, Ichthyosauria,
Squamata, Dinosauria and Pterosauria, of the diapsidan group, and
Theromorpha (Anomodontia) , Chelonia and Sauropterygia (Notho-
sauria and Plesiosauria) of the synapsidan group. As the reverse side
of this remarkable development, some of the older types, as Protero-
sauria, Phytosauria, Theromorpha and Nothosauria, disappeared with
THE TRIASSIC PERIOD. 4S
the period. Some of the orders came into the record so near the
close of the period that they play little part in its faunal history. Such
are the true crocodilians, the flying saurians (Pterosauria) and the scaled
reptiles (Squamata), which include the lizards, dolichosaurs, pythono-
inorphs and snakes. A true lizard has recently been reported by
Broom from South Africa.
The rise of the dinosaurs. — A foremost feature was the advent
and rapid evolution of the reigning reptilian dynasty of the Mesozoic.
Arising probably from some of the more primitive forms of the
rhynchocephalians, the dinosaurs (terrible saurians) were at first
generalized and rhynchocephalian in aspect, but later became more
specialized and diverged widely. While some were small and delicate
in structure, the more noted forms were gigantic and ungainly to
an extreme degree, especially the herbivores of the following periods,
when the deployment of the order was at its climax. Only the car-
nivorous forms (Theropoda) are known in the Trias, and these were
not usually as yet gigantic. Their general form is indicated by the
partially restored skeleton shown in Fig 340. The strong develop-
ment of the hinder parts, the relative weakness of the fore limbs, and
the kangaroo-like attitude, are the most obvious features. The bones
of these upright-walking forms were hollow, and certain other struc-
tural features resembled those of birds, among them the reduction
of the functional toes of the hind feet to four, with one of these much
shorter than the others so that their tracks were often three-toed, like
the famous "bird tracks" of the Connecticut valley. As the bones
of the Anchisaurus and allied genera are the only relics found with
these "bird tracks," it is supposed that they and their relatives were
responsible for them, which is made the more probable by the occa-
sional imprint of the fourth toe and of the fore foot. Most of the
bird-like characters of the dinosaurs are more probably due to parallel
evolution than to any immediate ancestral relationship to birds; more
remotely, birds and dinosaurs probably arose from a common stock.
The dinosaurs will claim much further attention in the following
periods. Even as early as the Triassic, they had a wide and signifi-
cant distribution, appearing in the Rocky Mountains, North Carolina,
Pennsylvania, Connecticut, Prince Edwards Island, England, Scotland,
France, Germany, India, and South Africa.
The advanced differentiation of the chelonians. — The turtle tribe
44 GEOLOGY.
was represented in the record by Proganochelys (Psammochelys) , a
highly specialized form belonging to the Pkurodira, from the Upper
Trias of Europe, as well as by others (Chelyzoon) of true cryptodiran
FIG. 340. — A Triassic dinosaur of the Connecticut valley, Anchisaurus colurus, restored
by Marsh, one-thirtieth of natural size.
affinities from the middle Trias,1 indicating, by their divergence and
specialization, a much earlier origin of the chelonian order.
The advent of the non-placental mammals. — Of peculiar interest
is the appearance of early forms of non-placental mammals. They
were small, and so primitive in type, that it is not altogether certain
that they were not mammal-like theromorphs. They are regarded,
however, as prototherian mammals, allied to the monotremes and
marsupials. The remains are fragmentary, teeth being the most
significant portions preserved. These show relations to the therio-
donts, and perhaps point to them as the source of descent, though
this is far from certain. Two genera are recognized in America
1 Recently described by von Huene.
THE TRIASSIC PERIOD. 45
(Dromotherium and Microconodori) and one in Europe (Microlestes).
This early appearance of the mammals, while yet the reptiles were
strongly ascendant, doubtless indicates a very early ancestry, suggesting
that perhaps the mammalian divergence began while yet their ancestors
were stegocephalians, as some believe, or in the very early stages of
the reptilian evolution in connection with the theromorphian develop-
ment, as others believe. In view of the mammalian dominance of
the recent ages, it is not a little instructive to note that the non-
placentals developed very slowly and feebly in America and Europe
during the whole Mesozoic era. Question has even been raised whether
the placental mammals are the descendants of these Mesozoic non-
placentals, with the suggestion that perhaps they had an independent
and equally early origin, a question on which future studies in Africa,
where the theromorphs had their strongest early development, is
likely to throw light.
The reptiles go down to sea. — Both wings of the reptilian horde
sent delegations to sea before the close of the period, the thalatto-
saurians and ichthyosaurians representing the more declaredly reptilian
line, and the sauropterygians (plesiosaurians) representing the mam-
malian branch. This similarity of movement and of adaptation has
associated the ichthyosaurs and plesiosaurs in geological thought,
though they are not close allies biologically. It is not difficult to
find good reasons for this movement to the sea. Besides the inevi-
table tendency of every masterful race to invade all accessible realms,
the renewed extension of the sea that set in during the Triassic period
and became pronounced before its close, especially invited this; for
the shallow waters, creeping out upon the land, with their now pro-
lific life, set tempting morsels before the voracious reptiles, on the one
hand, while on the other, the reduction of the land area and the re-
striction of their feeding-grounds, intensified by their own multipli-
cation, forced a resort to the sea.
The sauropterygians seem to have been the leaders in this move-
ment and to have become almost at once lords of the sea, and to have
preyed upon the previous rulers, the fishes. The nothosaurs were
the earlier and more primitive type of the sauropterygians and reached
their climax and closed their career within the period; but true plesio-
saurs were present. The accompanying restoration of the skeleton of
Lariosaurus, a genus confined to the Trias, illustrates by its well-
46
GEOLOGY.
developed limbs how certainly it had been a- land form. In later forms,
the limbs were modified into paddles, and all adaptation to locomotion
on land was lost. The ancestral affinities of the order are with the
anomodonts. The eighteen Triassic genera that have already been
FIG. 341. FIG. 342.
FIG. 341. — A Triassic sauropterygian, Lariosaurus balsami, restored; about one-tenth
natural size; from the Muschelkalk, Lombardy, Italy. (After Woodward.)
FIG. 342. — A primitive ichthyosaurian limb from the Middle Triassic of Nevada,
showing the elongation of the arm bones (H, humerus; R, radius; U, ulna)
characteristic of land animals. The structure is in contrast with that of the later
ichthyosaurs. (After Merriam.)
described show the great progress in evolution the order had made
before the close of the period.
Numerous primitive forms of ichthyopterygians (fish-limbed rep-
tiles) have recently been discovered by Merriam in the Trias of Cali-
THE TRIASSIC PERIOD.
47
fornia. These, the Thalattosauria 1 (Fig. 343), were a strange group of
true marine reptiles, probable descendants of some early rhyncho-
cephalian-like reptile. The skull, though of ichthyosaurian aspect,
differed widely from the ichthyosaurian skull in structure, and was
remarkable for the possession of numerous teeth on the palate. The
group apparently soon became extinct, without descendants. The
Thalattosauria were less remotely removed from their ancestors than
the well-known ichthyosaurs of the Jurassic period, whose limbs had
FIG. 343. — Skull of Thalattosaurus alexandrce (side and top), about f natural size.
(After Merriam.)
been, for the most part, converted into short broad flipper-like paddles.
In the newly-discovered Triassic forms the limb-bones were longer
(Fig. 342), and shaped more like those of the walking reptiles; the
hind limbs were often as large as the forward ones, while in other
characters they were more primitive.
In many respects the Triassic land life, both plant and animal
would fall into its more natural relations if its evolutions in the latter
part of the period were united with those of the Jurassic. While the
early Trias was closely akin, physically and biologically, to the Per-
mian, the later part was little more than the initial phase of the Jurassic.
1 Recently described by Merriam.
48 GEOLOGY.
Defined as it now is, the Triassic was a period of great transitions, in
which many types were inaugurated, but a few only were carried to
their characteristic developments.
The Marine Life.
The physical description has made it clear that the withdrawal
of the sea which restricted the marine life of the Permian was continued
into the Trias, during which it reached its climax, at least in North
America. There was then a very general emergence of what is
now land, and probably also of some tracts now submerged. The
marine life of the shallow-water type was therefore not only greatly
reduced, but because it occupied border tracts now buried, such record
as it made is mainly concealed from present examination; hi other
words, there was not only less life, but we know less relatively about
what there was. This was not equally true of other continents, although
measurably true of all, so far as present knowledge extends. To follow
the continuity of the shallow-water marine life, it is necessary to bring
together evidence from different continents. The question of supreme
interest is the mode by which the epicontinental sea life, crowded to a
minimum between the land and the deep sea, maintained its con-
tinuity, transformed its species, and, emerging at length, re-peopled
the shallow waters when they again spread out upon the continental
platform in the closing stages of the Trias and in the Jura.
When the sea readvanced on the North American continent, it
was primarily from the Pacific border, but was attended by incursions
along the Mackenzie Valley and from the Gulf of Mexico. It was
not till long after that an advance from the Atlantic made an accessi-
ble record. It is not clear that the sea ever completely withdrew
from the present land area on the Pacific border, but the fossils so
far recovered do not give clear evidence that there was there at all
times a harbor of refuge, or an embayment of shoal water of suffi-
cient area to develop, during the retreat of the sea, a definite provincial
fauna which subsequently spread with the advancing seas and made
itself felt as a pronounced faunal unit. Rather does the evidence
seem to point to a coastal tract merely, in which a restricted fauna
lived on and developed new species which migrated subsequently
as individuals, rather than as a faunal assemblage.
The transition tracts. — It was otherwise on the eastern continent.
THE TRIASSIC PERIOD. 49
It has been noted that the sea during the Permian period withdrew
from the northwestern portions of Europe, but lingered in the south
about the Mediterranean, and in the east in Russia. At the climax
of the retreat, the sea seems to have been confined more narrowly to
the Mediterranean region. In Asia, the sea had lingered in Turkestan
and northwestern India (Salt Range and Himalayas). In the latter
region the sea seems even to have advanced, for there is an uncon-
formity below the Permian, and, by retaining the ground thus acquired
till after the opening of Mesozoic time, afforded a theater for the great
transition from the Paleozoic to the Mesozoic. It is inferred from
the appearance of a specialized marine fauna in Siberia early in the
Triassic period, that the sea lingered on the continental platform some-
where in that quarter through the Permian and into the Mesozoic, and
that this also was an originating tract of faunas. These three regions,
the Mediterranean, the Himalayan and the Siberian, are the best known
tracts into which the shallow-water marine life of the Paleozoic retreated
and underwent transformation into the early provincial faunas of the
Mesozoic. It is quite certain that there was at least one other area
where important f aunal reorganization took place, for a notable fauna
suddenly appeared in the Middle Triassic, which does not seem to
have originated in any of these three districts. Very likely there were
still others.
The transition faunas. — In each of these areas an important rem-
nant of Paleozoic sea life seems to have persisted and to have under-
gone a radical and perhaps rather rapid evolution, such as might be
anticipated from the crowding of the great faunas of the Carboni-
ferous times into such limited areas, relieved only by the narrow coast-
border tracts and incidental dependencies. From these areas the
new faunas spread forth as the sea again extended itself upon the
land.
In the Indian basin there is a nearly continuous record of the transi-
tion from Paleozoic to Mesozoic marine life. Beds containing the
characteristic life of the Permian, the Productus fauna, are immediately
and conformably followed by beds containing the ammonite Otoceras,
and other forms of characteristic Mesozoic life. In the Productus
beds below the dividing horizon there are forms foreshadowing the
Mesozoic types, and in the beds above that horizon there are forms
of the Permian type that lived on past the dividing datum, and com-
50 GEOLOGY.
mingled with the Mesozoic forms; in other, words, there was a gra-
dation of the Paleozoic forms into the Mesozoic.
The transition fauna appears to have been richer in this region
than that in the Mediterranean basin. In the Yakutic stage, a division
of the early Trias, there are now known to have been two hundred
and twelve species of cephalopods in the Indian province, against twenty-
five known at the corresponding stage in the Mediterranean province
(J. Perrin Smith), which is the more notable since the latter has been
much more thoroughly studied. Because of the superior richness, as
well as the close continuity of the life of the Himalayan province, it
is entitled to be styled the cradle of the Mesozoic fauna par excellence.
More strictly, however, it was the cradle of a leading provincial fauna,
of the early Mesozoic only. The Mediterranean province soon developed
a vigorous rival fauna which deployed so strongly in the later Trias,
that it is regarded as the more representative fauna.
Concerning the early stages of the Siberian fauna very little is
known; but its peculiarities, as they were better revealed in a later
stage of the early Trias, leave little doubt of its independence of origin.
Of other transition provinces still less is known. It is significant,
however, that an important group of ammonites (Tropitidce) appeared
in the Eurasian provinces suddenly and in great force, toward the
middle of the Triassic. As these ammonites had no immediate ances-
try within these regions, it is inferred that they were immigrants from
some other originating tract, and this tract will doubtless be discovered
in time as the study of other regions progresses.
In a minor way, the general coast tract of all the continents, though
narrow, was doubtless the originating tract of some species, and per-
haps of minor faunas.
It is scarcely necessary to remark that the pelagic and abysmal
life of the main ocean is not embraced in this review, and is practically
unknown.
General nature of the faunal change. — In nearly all the Paleozoic
faunas, the brachiopods were a leading element, while the trilobites,
crinoids, corals, and orthoceratites, each in turn, gave distinctive
character to the successive faunas. In the Mesozoic era the ammon-
ites took the first place, followed by the pelecypods and the gastropods.
The ammonites (Fig. 344) were peculiarly fitted for distinguishing
successive horizons, not only because they were free forms, measur-
THE TRIASSIC PERIOD.
51
g h
FIG. 344. — A GROUP OF TRIASSIC CEPHALOPODS: a, Trachyceras austriacum Mojs.;
b-c, Tropites subbullatus Hauer; d, Choristoceras marshi Hauer; e-h, Ceratites
nodosus de Haan, lateral and ventral views of the shell and two sections of the
suture, one (g) showing the ventral or siphonal lobe with the lateral lobes and
saddles, the other (/i) snowing the dorsal or anti-siphonal lobes, with lateral lobes
and saddles.
52 GEOLOGY.
ably independent of bottom conditions, but because they were steadily
and rapidly advancing in organization, and because their shells were
so constituted as to delicately record their progress by reason of the
marvellously complex sinuosities of the sutures, and by the peculiar
registration of their life history. " The Ammonoidea preserve in each
individual a complete record of their larval and adolescent history,
the protoconch and early chambers being enveloped and protected
by later stages of the shell; and by breaking off the outer chambers,
the naturalist can in effect cause the shell to repeat its life-history
in inverse order, for each stage of growth represents some extinct
ancestral genus. These genera appeared in the exact order of their
minute imitations in the larval history of their descendants, and by
a comparative study of larval stages with adult forms, the naturalist
finds the key to relationships, and is enabled to arrange genera in
genetic series/71 On this account, not less than for their inherent
attractiveness, they merit foremost attention in the characterization
of the faunas.
The earlier Triassic faunas. — A great group of ammonites, embracing
more than 200 species, formed the leading feature of the early Indian
Triassic assemblage of marine life. These ranged from the ceratite
family, whose sutures were alternately lobed and serrate (see Fig. 345, a),
to the true ammonites in which the sutures were as tortuous as the
outline of an arbor-vitse leaf. The Otoceras, with ear-like suture lobes
(whence the name), characterized the earliest stage, while Gyronites,
Proptychites, Ceratites, and Flemingites in succession characterized
the later stages.
Among these later genera was the ceratite-like genus Meekoceras
(Fig. 345, c), which has special interest because it occurs also in western
and southeastern Idaho (Aspen Mountains) with the brachiopod genus
Terebratula (Fig. 345, h) and other forms that link together the Ameri-
can and Asian faunas. The alliance of these forms is sufficiently
close to indicate that before the close of the earlier Triassic epoch
migratory connections had been established between India and west-
ern America. It is significant in this connection that a fauna closely
related to this ceratite fauna of India occupied the Pacific border
in the vicinity of Vladivostok. In this are found a few species iden-
1 James Perrin Smith, " Comparative Study of Palaeontogeny and Phylogeny,"
Jour, of Geol., Vol. V, 1897, p. 517.
THE TRIASSIC PERIOD.
53
tical with those of India and others closely related to them. These
probably belong to a little later stage than their Indian relatives and
suggest that the sea-border tract of the North Pacific was the route
of migration from India to western America.
Somewhat later in the early Trias there appeared in the Siberian
region (Olenek River) a fauna having some of the same genera as the
Indian, but not the particular species common to the Indian and the
€ W
d e f h g i
FIG. 345. — A GROUP OF AMERICAN MARINE TRIASSIC FOSSILS. CEPHALOPODA: a, C 'era-
tiles whitneyi Gabb; b, Orthoceras blakei Gabb; c, Meckoceras. PELECYPODA: d, Mya-
cites humboldtensis Gabb; e, Corbula blakei Gabb; /, Myophoria alta Gabb; h, Tere-
bratula deformis Gabb. BRACHIOPODA: g, Pecten humboldtensis Gabb; i, Rhyncho-
nella cequiplicata Gabb.
Vladivostok fauna, and hence it is inferred that the Siberian-Indian
connection was later than the Indian-Vladivostok. There seems
also to have been some form of connection between the Siberian
province and the Idaho embay ment, for forms closely related to
those of Siberia are found in Idaho. After the Indian-Siberian con-
nection had been made, it would be possible for Indian species to
reach America either by way of Siberia and the Arctic coast, or by the
Pacific sea-shelf, and slight changes involving submergence or emer-
gence in the region of Behring Strait would change the combination
of the faunas. It was of course theoretically possible for some species
to have been carried by currents across the Pacific without following
the shallow-water zones, but this is improbable for all.
The Indian and Siberian provinces seem to have been distinct
from the Mediterranean province throughout the earlier Triassic. The
Mediterranean fauna was distinguished by many species of Tirolitince,
54 GEOLOGY.
a group of ammonites not found in the other provinces, while the
ceratite genera named above were wanting or very rare in it.
In California (Santa Ana Mountains) a few fossils have been found
which are characteristic of the earlier Triassic of the Alpine province.
If further discoveries should prove that the Mediterranean province
sent emigrants to the California coast, or received immigrants from
it, while Idaho, though in communication with Siberia and India did
not receive Mediterranean emigrants, an interesting question as to
the respective routes would be raised. The question is indeed raised
on other data in a later epoch.
The faunas of the central basin of Europe in the early Trias had
very uncertain shifting characters, a part being apparently developed
in fresh water, a part in isolated seas, and a part perhaps in dependen-
cies of the ocean. The salt-water life was scant, and its origin and
relations uncertain. It seems to have been largely independent of
the Mediterranean basin.
The middle Triassic faunas. — By the middle of the Triassic period
the provincial faunas had begun to intermingle extensively, and to
become composite faunas. The Mediterranean fauna gained access
to the Indian basin and to our western coast, and counter-migrations
were of course made possible. In western Nevada (Star Peak), species
are found that belong to the Muschelkalk horizon of the Alps. With
these are forms that are found also in the Siberian province, but the
Siberian and Mediterranean faunas, curiously enough, do not seem
to have directly mingled. The Mediterranean fauna is found on the
shore of the sea of Marmora, which suggests its line of connection with
the Indian basin, and representatives are thought to have been found
in the vicinity of Vladivostok, suggesting that its route to our western
coast lay along the north Pacific sea-shelf. The Siberian connection
may have been along the Arctic sea-shelf, in the main, but having com-
munication with the Pacific border at some point north of Nevada; or
the Nevada and Idaho basins may have been in communication with
one another at this time. The fauna was very rich in ceratites.
Stephanites superbus, Ceratites binodosus, and C. trinodosus of the Hima-
layas are characteristic types which give name to their respective
horizons.
In the Nevada embayment the fauna embraced certain cephak
pods that are unknown in the Siberian Trias, but have been found ii
THE TRIASSIC PERIOD. 55
the Mediterranean Trias. It, however, still embraced types that
appear to have been related to the Siberian forms, from which it is
inferred that a connection had been established between the western
coast and the Mediterranean province, while a connection with the
Siberian region was still retained, but that the Siberian and Mediter-
ranean regions were still not directly connected.
The later Triassic faunas. — During the later stages of the Triassic
period, a rather rich marine fauna flourished in California. A large
number of its species were identical with or closely allied to species
that abounded in the Mediterranean (Alpine) region. Many were
also common to the Himalayan region, from which it is inferred that
these provinces were in free communication with the west American
coast. On the other hand, the Upper Trias of British Columbia con-
tains a quite different fauna, containing a type that belongs to the
Siberian group. The British Columbian fauna is perhaps to be regarded
as the descendant of the Idaho fauna of the earlier Trias, with addi-
tions from Siberian sources, while the California fauna is perhaps a
derivative from the Mediterranean and Himalayan provinces by some
different route. It has been suggested by James Perrin Smith that
this was an Atlantic route, but the traces of the fauna along the route
are wanting, owing to the burial of the Triassic marine deposits along
the north Atlantic coast. A migratory route by way of Australia,
New Zealand, Antarctica, and South America is among the theoretical
possibilities.
As already indicated, present knowledge is not sufficient to show
the precise nature of the migrations between Europe, Asia, and America
during Triassic times, and the suggestions that have been made must
be held subject to revision. As developed in America, the special
faunas are not ample enough to fairly represent the life of the time,
and a general sketch disregarding geographic limits is here substituted.
General nature of the fauna. — The earliest fauna was markedly
restricted. In some degree this may be more apparent than real on
account of the imperfection of the accessible record, but in the main
it was undoubtedly real and due to the physical limitations already
sketched. At the same time, there was an increase in the relative
degree of differentiation. The conditions which repressed the life,
while they reduced the number of individuals, species, and genera,
forced them to diverge more and more from one another to accommo-
56 GEOLOGY.
date themselves to the scant opportunities offered. This is shown best
in the development of the land and fresh-water life, but it is also ex-
pressed in the marine life.
The cephalopods again in leadership. — The most conspicuous fea-
ture was the re-ascendancy of the cephalopods in the form of the
ammonites, which had a marvellous development during the period,
reaching a thousand species. Their evolution was made the more
notable because their structural changes were conspicuous and showed
declaredly the advance of each stage upon the preceding. While the
straight orthoceratites, the simplest type of the cephalopods, still
persisted with notable tenacity, and the simplest coiled nautiloid
forms with plane septa also persisted, the closely coiled, intricately
sutured forms overwhelmingly predominated. There also appeared
at this time the first of the known cephalopods of the cuttlefish type
(Dibranchiata) . The deployment of the cephalopods was therefore
varied and comprehensive to a degree never reached before, and per-
haps not much surpassed afterward, although the culmination of this
evolution took place in the succeeding period. The old forms, how-
ever, the orthoceratites and even the goniatites, make their last appear-
ance in this age, and were not participants in the culminating fauna
of the Jurassic. The remarkable commingling of old and new forms,
orthoceratites, nautiloids, goniatites, ceratites, and ammonites, with
its suggestiveness relative to derivations and transitions, makes this
one of the most instructive assemblages in the history of the cephalo-
pods.
Old and new gastropod types. — A similar commingling and tran-
sitional aspect was presented by the gastropods. The Paleozoic gas-
tropods possessed apertures which were " entire"; that is, nowhere
drawn out into a tube for the reception of the siphon. Sometimes
there was a recess or slit in the aperture, but no tube or canal. The
progressive branch of the Triassic gastropods, however, developed
such tubes and originated the canaliculate class. By means of the
canaliculate shell, the used waters from the body chamber were carried
a longer distance from the orifice by which fresh waters entered the
chamber, and thus served a hygienic function.
The transition and rise of the pelecypods. — The Triassic bivalves
do not show the transition from the old to the more recent by as con-
spicuous features as the cephalopods and gastropods, but it was scarcely
THE TRIASSIC PERIOD. 57
less real. The number of pelecypods was relatively large, and the
majority of the genera were of the modern type, some being even
identical with living genera, but with these were mingled about half
as many that still bore a Paleozoic aspect.
The change in the type of brachiopods. — The dominant brachio-
pod types of the late Paleozoic were outwardly distinguished by broad
forms and extended hinge lines, as the spirifers and orthids; the
narrower beaked or rostrate forms represented by the rhynchonellas,
formed a very respectable minority. In the Triassic period the ros-
trate forms Rhynchonella, Terebratula, and allied genera became the
predominant class, and have remained so ever since. The spire-bear-
ing forms (Spiriferina, etc.) were still present, though rare, and the
loop-bearing terebratuloids became much more conspicuous in the
Mesozoic faunas.
The echinoids become the leading echinoderms. — Although the
echinoderms were not at all strongly represented in the Triassic fauna,
the period marks the transfer of echinoderm leadership from the crin-
oids to the sea-urchins. It also marks a structural change in these.
Beginning with the Triassic, the echinoids had twenty rows of plates
in belts of two rows each, as the invariable rule, where as the Paleozoic
forms had more. At first they retained the previous regular pen-
tamerus symmetry, but later this gradually gave place to a bilateral
symmetry. Many of the Triassic forms were armed with club-shaped
spines. The crinoids were generally few, though sometimes locally
abundant. Starfishes and brittle-stars were present, but not abundant.
The corals. — While corals were generally rare, in certain favored
localities, as at St. Cassian, they were rather prolific. While some
of them resembled the Paleozoic forms in being simple and cup-shaped,
the compound species took on the modern (hexacoralla) form, and
the compound Paleozoic (tetracoralla) type disappeared. These later
compound corals do not seem to have been derived from the Paleozoic
compound forms, but from some simple type.
Other forms. — The marine arthropods seem to have been unim-
portant. Sponges were present in Europe, but have not been found
in America; bryozoans were very few; and foraminifera were abundant
in favorable situations in Europe. All of these groups presented more
or less transitional or modern phases.
While the general aspect of the Triassic marine faunas was emphati-
58 GEOLOGY.
cally revolutionary, it is important to note/ in view of beliefs once
current, that it was transitional, and not an abrupt substitution of a
new fauna for an old one. Paleozoic types lived side by side with
the later forms, though usually represented by new genera. This
overlapping and commingling of old and new clearly indicates the
gradation of the earlier into the later. The transition was very ex-
traordinary, however, in the apparent rapidity of its progress, and in
the extent to which it affected all classes. The fact that most of the
new forms were already present in the earliest Triassic indicates that
the transition was chiefly made earlier, in the Permian, as already
noted. The fundamental cause was with little doubt the readjust-
ment of the earth's surface to internal stresses, and the physiographic
and climatic changes consequent upon this readjustment.
CHAPTER XIII.
THE JURASSIC PERIOD.
The eastern part of the continent. — Formations of Jurassic age
have not been certainly identified in the eastern half of the continent.
Considerable beds which out-crop along the western margin of the
Atlantic Coastal Plain have recently been described as Jurassic;1
but this correlation, at least for the upper part of the series involved,
cannot be looked upon as probable, much less as established. The
lowest of the beds in question (the Patuxent and Arundel formations
of Maryland), lying at the base of the 'Coastal Plain series, are ten-
tatively referred to the Jurassic 2 with more reason ; but even here
nothing has yet been discovered which proves this to be their age.
The beds in question are thin (350 feet maximum) and closely asso-
ciated with the Lower Cretaceous of the locality where they occur.
The basis for their tentative reference to the Jurassic, rather than
the Lower Cretaceous, is (1) their unconformity below other Lower
Cretaceous beds, and (2) the presence of certain reptilian fossils which
are thought (Marsh) to be characteristic of the Jurassic rather than
of the Cretaceous. Concerning the first point it is to be noted that
there is an unconformity in the Lower Cretaceous above the doubtful
Jurassic, so that this argument cannot be said to have great weight.
These possible Jurassic beds do not appear to be of marine origin.
If any of the Coastal Plain beds are to be looked upon as Jurassic,
their position and relations emphasize the greatness of the break
between this system and the preceding. The Newark series had been
uplifted, tilted, faulted and subjected to extensive erosion before the
deposition of the doubtful Jurassic beds, which, in their constitution,
1 Marsh, Am. Jour. Sci., Vol. II, p. 433, 1896. See also Gilbert, Ward, Hill, and
Hollick, Vols. IV and V, 1897.
2 Clark, Journal of Geology, Vol. V, p. 479. Also Maryland Geol. Surv., Vol. I,
p. 190.
59
60 GEOLOGY.
their distribution, and their stratigraphic relations are much more
closely allied to the Lower Cretaceous than to the Triassic. They
constitute the beginning of the great series of undeformed beds
underlying the Coastal Plain.
If deposits were not making within the present area of the land
along the Atlantic coast during the Jurassic period, geological processes
of another sort must have been there in operation. As already noted,
the Triassic period seems to have been closed by the deformation of
the Triassic beds, accompanied by faulting and the injection of lava
into the faulted series. Since the uplifted and deformed Triassic sys-
tem, along with the Appalachian Mountain region, was essentially
base-leveled before the Cretaceous period was far advanced, the inter-
vening Jurassic period must have been a time of great erosion, so far
as the Appalachian belt and the Piedmont plateau to the east were
concerned. The sediments worn from these older beds were of course
deposited somewhere, and the site of deposition seems to have been
chiefly east of the present coast.
Aside from the doubtful beds referred to above, no Jurassic strata
are known on the eastern side of the continent. Marine Jurassic beds
have been recently reported from Texas,1 but they lie to the west of
the ranges corresponding to the Rockies. These Jurassic beds are
limestone, and though the exposures are limited, their connections
are probably southward with the Jurassic of Mexico. In eastern Mexico,2
Jurassic beds of marine origin are somewhat widespread, the later
formations of the period being more extensive than the earlier. The
Jurassic system is also said to be represented in the western part of
Cuba.3
The broad interior of the continent, including most or all of the
area which emerged during the closing stages of the Paleozoic, appears
to have remained above the sea during the Jurassic period, as during
the Triassic. The area of sedimentation was even more limited than
during the Triassic period, especially at the east, though la'er in the
period marine sedimentation was more widespread in the west than
1 Cragin, Discovery of Marine Jurassic Rocks in Southwestern Texas. Jour, of
Geol., Vol. V. See also Hill, Am. Jour. Sci., Vol. II, 1897, p. 449, and Physical Geog-
raphy of Texas, Topographic Atlas, U. S. G. S.
2 Bol. del. Inst. Geol. de Mexico, Nos. 4, 5 y 6, 1897, and Bain, Jour, of Geol., Vol. Vr
p. 384.
3 Hill, Cuba and Porto Rico.
THE JURASSIC PERIOD. 61
at any time since the close of the Pennsylvanian period. Like the
eastern part of the continent, the interior was suffering erosion, but
since its altitude was probably low, the erosion effected was less con-
siderable. The post-Paleozoic, pre-Cretaceous erosion in the interior
is less well determined than in the Appalachian belt and the Pied-
mont plateau farther east.
The western part of the continent. — In contrast with the eastern
and interior portions of the continent, deposition was in progress in
many parts of the west. Along the Pacific coast, the deposition was
marine ; in the western interior, in the early part of the period, it was
in partially inclosed bodies of water which were sometimes salt, some-
times brackish, and sometimes fresh, or in dry basins and valleys.
Late in the period, an arm of the sea extended itself over a great area
of the western interior (see Fig. 346). For convenience, the terms
Lower, Middle, and Upper Jurassic are here used in connection with
the system in the west, though they are not in general use in North
America.
The Lower and Middle Jurassic of the Pacific coast. — During the
epoch represented by the Lower Jurassic beds, corresponding in a
general way with the Lias of Europe, marine deposition was taking
place on the Pacific coast 1 (California and Oregon) west of the Basin
land. Much of the Jurassic of the coastal belt is concealed beneath
igneous rock of later origin, so that its original extent is not known.
In the latitude of Nevada and Utah, it extended east to longitude 117°.
Where both are present, the Lower Jurassic beds generally rest on
the Trias conformably, though the younger beds overlap the older
system at some points, and fall short of it at others, and locally (some
points in the Sierras) there is unconformity between them. The
deposits of the Lower Jurassic embrace all the usual sorts of sedi-
mentary rocks. Beds of corresponding age are not known in British
Columbia, and this part of the coastal belt was probably land, and
suffering erosion.2 Early Jurassic beds occur in some of the islands
1 For the Jurassic of the Pacific coast, see Hyatt, Bull. Geol. Soc. of Am,, Vol. Ill
and Vol. V, both articles chiefly paleontological ; Meek, Paleontology of California,
Vol. I, and the following folios of the U. S. Geol. Surv. : Bidwell Bar, Colfax, Downie-
ville, Jackson, Lassen Peak, Maryville, Mother Lode, Nevada City, Pyramid Peak,
San Luis, Sonora, Truckee, Cal., and Roseburg, Ore.
2Dawson, Science, March 15, 1901.
62
GEOLOGY.
FIG. 346. — Map showing the areas where the Jurassic system appears at the surface
in North America. The conventions are the same as in preceding maps.
THE JURASSIC PERIOD. 63
farther north. The fossils of the early Jurassic beds point to faunal
connections with central Europe.1
The Middle Jurassic of the Pacific coast, corresponding in a gen-
eral way with the Lower Oolitic of England, and the Middle Jura of
the continent of Europe, has a distribution similar to that of the Lower,
and its close association with the latter allies it closely with the Trias
stratigraphically. The auriferous slates of California, a meta-sedi-
mentary series, involve some Jurassic beds as well as those of greater
age (Trias, Carboniferous, and Silurian).2
Lower and Middle Jura in the western interior. — Between the
meridians of 106° and 112°, and the parallels of 35° and 42°, there
are beds of a sandy nature which have often been referred to the Ju-
rassic system. Their distribution is more restricted than that of the
Permian and Triassic Red Beds already referred to. The lower beds
which have been regarded as Jurassic are without fossils, and corre-
spond, in their general character, with the Permian and Triassic of
the same region.
The beds of the western interior usually referred to the Permian,
Triassic and early Jurassic, have the appearance of a unit. Their
general (though not universal, see p. 26) conformity among them-
selves and with the Carboniferous below, seems to show that their
deposition followed the Carboniferous without notable interruption
in most places; but such evidence is to be received with caution, as
seeming conformities sometimes conceal great intervals. Since their
thickness is not great — 600 feet perhaps is an average — and since so
slight a thickness of coarse sediment does not seem to call for a long
period of time, there is some doubt whether any part of the Red Beds
is so young as Jurassic. The region of the Red Beds may have been
a land area, and subject to degradation during the early part of the
Jurassic period. In the later part of this period, as will be shown
later, the sea found access to the northern part of the Great Plains
area. If the Red Beds were suffering erosion during the earlier part
of the Jurassic period, and the region to the south throughout the
whole period, the thickness of the Permo-Triassic formations may
have been greatly reduced before the deposition of the Upper Jurassic
and Lower Cretaceous formations. In any case, the existence of
1 Smith, J. P., Jour, of Geol., Vol. 111,1895, pp. 377-8.
2 Idem., Bull. Geol. Soc. of Am., Vol. V, p. 257.
64 GEOLOGY.
Early and Middle Jurassic beds in the western interior must be looked
on with question.
The Upper Jurassic. — During the Upper Jurassic (Upper and
Middle Oolitic of England) epoch, the areas of sedimentation were
greatly changed, indicating considerable changes in geography. On
the Pacific coast of the United States, in the latitude of California, the
sea appears not to have extended east of the Sierras. The Golden
Gate series of the Coast Range perhaps belongs to this stage ; 1 but in
northern British Columbia, where the Lower and Middle Jurassic beds
have little representation, the sea extended farther east than during
the earlier part of the period. South of the United States, Jurassic
beds of marine origin occur in western Mexico (Sonora), but it is not
known to what part of the system they belong.
In addition to marine sedimentation along the Pacific coast, the
sea had access to a large area in the western interior, and covered
much of Wyoming,2 Montana,3 Utah, and Colorado, and parts of
several other states.4 This is shown by the presence in these
States of sedimentary beds containing marine Upper Jurassic fossils.
The beds are chiefly exposed in the mountains (Wasatch, Uinta, Black
Hills, etc ) where the erosion which followed the uplift and deformation
of the strata has discovered their edges.5 The general relations of land
and water in the west in the late Jurassic are shown in Fig 348, but
it should be said that the distribution of the Jurassic in the west is
so imperfectly known that no map showing the relations of land and
water can lay claim to accuracy.
The avenue through which the sea reached this region has not been
determined, but the fossils are so unlike those of the Californian coast
as to have led to the inference that the waters of the interior did not
come in from the southwest. The absence of Jurassic strata over
1 Fairbanks, Jour, of Geol., Vol. Ill, pp. 415-433
2 Logan, Jour, of Geol., Vol. VIII, p 241; Knight Bull. 45, Wyo. Exp. Station,
and Bull. Geol. Soc. of Am., Vol. XI, pp. 377-88, and the following folios, U. S. Geol.
Surv.: Hartville, Wyo., Yellowstone Park, Wyo., New Castle, Wyo.-S. D.
3 See Little Belt Mountain, Fort Benton, Three Forks and Livingston folios, U. S.
Geol. Surv.
4 For South Dakota, see Darton, 21st Ann Kept. U. S. Geol. Surv., Pt. IV, and the
following folios, U. S. Geol. Surv.: Oelrichs and Edgemont, S. D.-Neb.
6 In addition to the above folios, U. S. Geol. Surv., see also the following: Anthra-
cite and Crested Butte, Ten Mile, and Telluride.
THE JURASSIC PERIOD.
65
the belt marked as land in Fig. 346, lends further support to the con-
clusion that a land barrier separated the interior waters from those
of the Calif ornian coast. The identity of many species from the Upper
Jurassic beds of the Queen Charlotte Islands and from the Frazer
River in British Columbia, with those of the western interior, imply
either connection between these areas, or connection of both with
some point along the migratory routes which the marine life followed.
Whether this connection was direct through British Columbia, or
FIG. 347. — A cliff of Jurassic rock, 1£ miles west of Bluff City, Utah.
(Cross, U. S. Geol. Surv.)
whether it was by way of Alaska, east of the Rockies, is unknown.
The similarity of the Upper Jurassic marine fossils of America and
of Russia, more fully set forth later, would be explained by either
of these connections; so also would the fact that a few of the species
of the Californian coast are identical with those of the Queen Charlotte
Islands. Either connection would call for an extension of the Jurassic
beds of Montana, Dakota, Wyoming, etc., to the north or northwest.
In spite of the fact that such extension has not been demonstrated,
66
GEOLOGY.
the most rational explanation of the Marine Jurassic beds in question
is that they were deposited in a great dependence of the north Pacific
or the Arctic Ocean,1 which covered
the area where the strata occur.
If this be correct, it must be sup-
posed that the northerly extension
of the marine Jurassic of the United
States has been concealed by later
beds, or destroyed by erosion, or
not discovered.
The presence of fresh-water beds
of possible Upper Jurassic age (the
Morrison [Atlantosaurus, Como] beds
of Colorado, Montana, and Wyo-
ming) in some parts of the western
interior would, were their age estab-
lished, show that salt water was
not continuously present at all points
where deposition was taking place.
The Jurassic age of these beds
seems, however, to be doubtful (see
p. 119) .2
The change in geographic con-
ditions in the western half of North
America, between the Middle and
Upper Jurassic, as shown by the
distribution of the corresponding formations, was as great as that
which sometimes separates one period from another. It was equally
great in other continents, but not in other parts of our own.
Thickness. — The total thickness of the system in California does
not exceed 2000 feet (in part tufa) . Farther east, in western Nevada,3
1 Neumayr suggested (Denkschr. K. Akad. Wiss. Wien, 1893, pp. 301-302) the
Arctic rather than the Pacific connections of the Jurassic deposits; but the similarity
of faunas of the north Pacific coast and the western interior, have commonly been
thought to point to the other conclusion.
2 Lee, Jour, of Geol., Vols. IX and X, pp. 343-52 and 36-58 respectively; Darton
and Smith, Edgemont and New Castle, South Dakota, folios, U.S. Geol. Surv., and
Williston, Jour, of Geol., Vol. XIII, p. 338.
3 King, Survey of the 40th Parallel, Vol. I.
FIG. 348. — Map showing the general re-
lations of land and water in the west-
ern part of North America during the
later part of the Jurassic period. The
black areas represent known areas of
Upper Jurassic. The dotted line is
the conjectured outline of the bay.
(After W. N. Logan.)
THE JURASSIC PERIOD. 67
nearer the land whence sediment was derived, the system attains
a thickness of 5000 to 6000 feet, being made up of 1500-2000 feet of
limestone below, and 4000 feet of slates above. In its western interior,
it is far less.
Surface distribution and position of beds. — In spite of the fact
that the Jurassic beds are somewhat widely distributed, they do not
now appear at the surface over large areas. In many places they
are covered by younger beds, and from some areas where they
once existed they have been removed by erosion. In some areas
they retain their original position, while in others they have been
tilted, or even folded and metamorphosed. This is especially true
in California, where the slates of the system contain many of the
gold-bearing quartz veins of the region.
With the sedimentary beds of the Pacific coast (California) there
are considerable beds of fragmental igneous rock, showing that
volcanic forces were here active on a somewhat extensive scale during
the Jurassic period.
Jurassic in Alaska. — Jurassic formations are known at somewhat
widely separated points in Alaska, but their horizon within the sys-
tem has not been established.1
CLOSE OF THE JURASSIC.
Orogenic movements. — At the close of the Jurassic period consider-
able disturbances occurred in the western part of North America.
Nearly 25,000 feet of strata, 7000 feet of which belong to the Triassic
and Jurassic, began to be folded into the Sierras,2 and the Cascade
and Klamath 3 Mountains farther north perhaps began their growth
at the same time. In northern California and southern Oregon, in
the latitude of the Klamath Mountains, the coast was somewhat far-
ther west than now, after this period of erogenic movement.3 There
is some reason to think that the axes of these mountain ranges were the
scenes of earlier disturbances (Vol. II, p. 584), but of these earlier move-
ments the record is meager. Their existence is inferred from the
greater complexity and metamorphism of the pre-Triassic beds. It
'Spurr, 20th Ann. Kept. U. S. Geol. Surv., Ft. VII, pp. 235-6.
2 Whitney, Geology of California, Vol. I, and Am. Jour. Sci., Vol. XXXVIII,
1864; and Fairbanks, Am. Geol., Vol. IX, 1892, Vol. XI, 1893.
8 Diller, Bull. Geol. Soc. Am., Vol. IV, p. 224, and 14th Ann. Kept. U. S. Geol. Surv.
68
GEOLOGY.
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THE JURASSIC PERIOD. 69
is not to be understood that the Sierras and Klamaths attained moun-
tainous heights immediately at the end of the Jurassic period, or that
they have not had subsequent periods of growth. In the Klamath
Mountains, for example, there are deformed beds of late Tertiary age.
It is probable that the Coast Range of California began its history
at the same time, for deformed Jurassic beds (Golden Gate series)
underlie the Lower Cretaceous unconformably in the axis of the range;1
but the movements which gave the Coast Range its present form, or
its present form as modified by erosion, took place at a much later
time.
Farther east, the Humboldt ranges of Nevada are thought to have
been started in their development at about the same time as the ranges
already mentioned. More than 20,000 feet of Jurassic and Triassic
strata are involved in their folds. It is possible that other mountains
of the west, the cores of which had been islands throughout the Triassic
and Jurassic periods, were affected by renewed uplift at this time of
general disturbance. The erogenic disturbances at the close of the
Jurassic may have been comparable in kind and in extent to those
which affected the continent at the close of the Paleozoic, but they
were probably of a lower order of magnitude. The disturbances which
have been definitely referred to this period were certainly less extensive,
and less intense.
The position and relations of the Jurassic formations at various
points in the west are shown in Figs. 351 to 354.
Changes in geography. — At the close of the Jurassic, geographic
changes equal in extent to those of the closing stages of the Paleozoic
FIG. 351. — Section showing the relations of the Jurassic system near Telluride, Colo.
Td, Triassic (Dolores formation); Jme, Jurassic (?)(McElmo formation); Kd and
Kmc, Cretaceous (Dakota and Mancos formations); Esm, Eocene (San Miguel
formation) ; dm and gd, igneous intrusions. (Purington, U. S. Geol. Surv.)
are not recorded; yet the changes were great, though in regions less
well known than those affected by the deformative movements which
occurred late in the Paleozoic era. Much, if not all, of the great Upper
1 Fairbanks, Jour. Geol.. Vol. Ill, pp. 415-430, and Smith, Bull. Geol. Soc. of Am.,
Vol. 5, pp. 257-8.
70
GEOLOGY.
Jurassic gulf of the northwestern part of the continent disappeared
at the close of the period.
It should perhaps be added that until very recently no part of
FIG. 352. — A section in southern Montana. ^=Archean; C, Cambrian (Flat-
head and Gallatin formations) ; D, Devonian (Jefferson and Three Forks for-
mations); Mm, Mississippian (Madison formation); Pq, Pennsylvanian (Quad-
rant formation) ; Je, Jurassic (Ellis formation) ; Kd, Kmc, and Kl, Cretaceous
(Dakota. Colorado, and Montana, and Laramie formations) ; bbr, igneous rock.
(Peale, U. S. Geol. Surv.)
the geology of the United States has received less careful study, and
is less well understood, than that of the Permian, Triassic, and Jurassic
FIG. 353. — Section showing the relation of the Jurassic beds in the West Humboldt
range of Nevada. M, Archean; T, Red beds; Jst, Triassic (Star Peak); J,
Jurassic; Nh, Pliocene; P, Pleistocene. (King, U. S. Geol. Surv.)
systems of the western half of the continent. The reason is twofold:
(1) The systems are in regions where relatively little detailed work
FIG. 354. — Section in the Sierras of California, showing the Jurassic (or Jura-Trias)
system where it has been metamorphosed, and where it is associated with igneous
rock, grd and dpi, igneous rock, probably of Jurassic or Cretaceous age; si and
slm, Jura-Trias (?) schist; Na, Nr, and Pb, igneous rock of late Tertiary and Pleis-
tocene age. (Lindgren, U. S. Geol. Surv.)
has been done, and (2) the non-marine character of most of the beds
and their paucity of fossils, makes their interpretation difficult.
FOREIGN JURASSIC.
Europe. — Jurassic strata are exposed in many and widely separated
localities in Europe, though for the most part in relatively small areas
only. They appear at the surface in a wide belt across England, from
THE JURASSIC PERIOD. 71
the Bristol channel on the southwest to the mouth of the Humber
on the northeast. They encircle, with outward dip, the ancient meta-
morphic rocks in southern France, and with inward dip they form
the border of the Paris basin, the central part of which is filled with
younger beds. East of the Paris basin, the upturned beds of the sys-
tem appear in the Jura Mountains (whence the name) and the Alps,
and farther east in various parts of the complex mountain system
of south central Europe. In the lower latitudes of the continent
they are to be found in Portugal, in some parts of Italy, in the Balkan
peninsula, in the Crimea, and in the Caucasus Mountains, and in the
north over large areas in central and northern Russia. The only
considerable tract where they do not occur is the northwestern part
of the continent.
This enumeration shows that the Jurassic system is widely dis-
tributed in Europe, but as with older systems its present distribution
at the surface is no measure of its real extent. It has been thought
that the Jurassic of England is probably continuous with that of France
beneath the English Channel, and thence, by way of southeastern
France, with those parts of the system which appear about the Med-
iterranean, and by way of Belgium, the Netherlands, and the Ger-
man lowlands, with those parts of the system which appear in Poland
and Russia. In northern Russia, the surface distribution of the sys-
tem corresponds approximately with its real distribution. In southern
Russia, on the other hand, the Jurassic beds are probably widespread
beneath younger formations. Jurassic strata of marine origin have
a much wider distribution in Europe than in North America, and
hence it is inferred that a larger proportion of the former continent
was submerged during at least some part of the period.
It is not to be inferred that all parts of the Jurassic system are
so widely distributed. The lower part is less widespread than the
Middle, and the Middle is less widespread than the Upper. In this
respect, the North American and European continents are in harmony.
The areas of Jurassic deposition in Europe are commonly grouped
into three provinces, the southern, the central, and the eastern;
but they are equally well grouped in two provinces, a Mediterranean
province and a Boreal province.
It is not to be understood that these provinces, whether three or
two, were absolutely separated from one another, or that they were
72 GEOLOGY.
equally distinct at all stages of the period;1 but their separation was
sufficient to give rise both to different conditions of sedimentation, and
to different conditions of life. The changes which took place during
the period are best understood by a study of the character and
distribution of the various parts of the system.
It may be noted at the outset that the Jurassic system of Europe
has been studied in great detail, and that the correlation of its different
horizons has been carried to a degree of refinement not known in any
older system in Europe, and not in any system in America. About
thirty well defined horizons have been made out for central and western
Europe, and these have been found to hold over wide areas outside
the region where they were first recognized. The definition of these
horizons is based on fossils, and chiefly on the fossils of free-swimming
animals. The fixed forms of life, and those which are confined to
shallow water, ranged less widely, and their fossils do not enter into
the definition of the many horizons in any important way. Some of
the horizons which are but a few feet in thickness are traceable over
large areas of the continent, though not beyond the limit of a geo-
logical province. Thus in Great Britain, 17 distinct ammonite zones
have been recognized in the Lower Jura (Lias) alone, and this zonal
succession has been found to apply to all central and western Europe.2
By the definition of these provinces and by the detailed study of
the distribution of the various types of life within them, much has
become known concerning the geography of the Jurassic period beyond
that which is shown by the mere distribution of the Jurassic beds.
Although the subdivision of the Jurassic system has been carried
to a high degree of refinement, the many zones are grouped into a
few principal divisions as follows:
Germany, 2000'-3000/. England, 4000'-5000'.
jr Jura Upper Oolite
rhite Jura, Malm) (Portland Oolite)
Upper J
(Whil
Middle Jura , Middle Oolite
(Brown Jura, Dogger) (Oxford Oolite)
Lower Jura Lower Oolite
(Black Jura, Lias) (Bath Oolite)
Lias
Lower Jura or Lias. — Conditions similar to those of the last stage
of the Triassic period affected central and western Europe during
1 De Lapparent, op. cit., p. 1105.
2Geikie, op. cit., p. 1136.
THE JURASSIC PERIOD. 73
the early part of the Jurassic, and the Lias frequently overlies the
Trias conformably, and with no very definite plane of demarkation.
The early Jurassic beds are mostly marine, and were deposited in waters
which were shallow, and the sediments were mostly clastic and fine.
Near its eastern border in central Europe, the Lias contains coal in
quantity, as many as 25 workable coal beds occurring at one point
in Hungary. In other places, too, as in England, there are indications
of non-marine conditions of sedimentation, both in the fossils and
in the thick beds of earthy iron carbonate of commercial value.1 Some
of the Liassic shales of Germany afford oil.2
The Lias of southern Europe is more largely calcareous than that
of central Europe. Red marble, carrying abundant ammonites, is a
characteristic formation of the eastern Alps, the Carpathians, the
Apennines, and in Spam.
In the eastern province of Europe, the Lower Jura is unknown.
It occurs in the southern part of Russia (the Caucasus Mountain
vicinity), but this is classed with the southern rather than with the
eastern province.
Middle Jura. — The Middle Jura, and especially its upper part,
is somewhat more widespread than the Lower, in central Europe, indi-
cating progressive sea-encroachment. During the early part of the
epoch, the deposits, like those of the Lias, were uniform over consider-
able areas, but during the later part, they became more diverse so
far as their fossils were concerned, showing that conditions sufficiently
different to influence life, affected various parts of the province.
Oolite is one of the characteristic formations of the Middle Jura
of central Europe as of England. The prevalence of this rock origi-
nally gave origin to the name Oolitic for all that part of the system
above the Lias. The oolitic structure affects not only much of the
limestone, but also lenses and beds of iron ore, in various parts of the
central province. In England, parts of the Middle Jurassic contain
estuarine and fresh-water beds, and sometimes (as in Yorkshire) coal
seams and beds of iron ore. Marine Upper Jurassic beds overlie the
non-marine parts of the Middle Jurassic.
In southern Europe, the Middle Jura has but little representation,
or has not been thoroughly differentiated. In the eastern province,
1 Geikie, op. cit., p. 1132.
2 Idem., p. 1154.
74
GEOLOGY.
the larger part of the Middle Jura is wanting, 'though the upper horizons
may be present. Middle Jurassic beds in Lat. 71° have yielded species
of sub-tropical ferns, cycads, and conifers.1
The Upper Jura. — The encroachment of the sea which was in progress
during the Middle Jurassic time reached its maximum a little later
¥IG. 355. — Sketch-map of Europe in the Middle Jurassic period. The shaded areas
are areas of deposition, chiefly marine. (After De Lapparent.)
as shown by the wide distribution of the Upper Jurassic formations;
but before the end of the epoch the sea began to withdraw, for some
parts of the area which had been submerged became land, while other
parts were occupied by lakes and bodies of brackish water.
The formations of the Upper Jurassic in central Europe contain
much more limestone than those of the lower divisions of the system
in the same province. Corals and sponges were especially abundant
in central Europe, and contributed much to the making of the light-
colored limestone which, on the continent, has given this member
1 De Lapparent, Traite de Geologic, p. 1142.
THE JURASSIC PERIOD.
75
of the system the name of the White Jura. Some of the sandstones
also are white.
One of the notable phases of the Upper Jurassic in central Europe
is the Solenhofen limestone of southern Germany. This stone is so
fine and so even grained, and at the same time so workable and so
strong, that it has come into use the world over for lithographic pur-
poses. It is also remarkable for the perfection of its fossils, including
FIG. 356. — Sketch-map of Europe showing the relations of land and sea during the
later part of the Jurassic period. The shaded areas were submerged. (After
De Lapparent.)
such delicate parts as the gauzy wings of insects. This limestone
has been ascribed to a late stage of the epoch, after the land to the
north had emerged. The newly emerged beds, largely limestone, were
still soft, so the hypothesis runs,1 and the material washed down from
them gave origin, after deposition, to the lithographic stone. Others
have thought to see in the even grain of the stone a chemical precipi-
tate. Whatever the origin of the limestone, the perfection with which
1 Neumayr, loc. cit., p. 318.
76 GEOLOGY.
delicate parts of various sorts of animals are preserved, shows that
the conditions of sedimentation were unusual.
The uppermost horizons of the Jura are wanting in most of the
central provinces of Europe, but in England and northern Germany,
and at a few points elsewhere, brackish water deposits of the last stages
of the epoch are known. In England, these beds (Purbeck) are closely
associated with the oldest beds (Wealden) of the next period.
The Upper Jurassic of southern France and of the Mediterranean
province, largely limestone,1 differs from that of central Europe in
recording more uniform conditions. In Portugal, however, the higher
members of the Upper Jura are not altogether marine, and the system
grades up into the non-marine Lower Cretaceous.2 Even where the
upper part of the Jurassic of southern Europe is marine, it is closely
connected with the Lower Cretaceous. In this respect, southern Europe
is in contrast with the central part of the continent, where the separa-
tion of the Jurassic from the Cretaceous is complete.
In the eastern province of Europe, the Upper Jura (with late Middle
Jura) is widespread. The sea which covered this province is thought
to have come in from the north, and to have covered much of Russia.
The strata of this province are rather uniform in composition, and
mainly clastic, the sands being often glauconitic. In the eastern as
in the southern province, the Jura goes over into the Cretaceous with-
out stratigraphic break.
The Jurassic system attains a very considerable thickness both
in the central and southern provinces.
The frequent alternations of muddy, sandy, and calcareous sedi-
ments, which are a marked feature of the system in England and north-
ern France, indicate frequent pauses and reversals of the changes
affecting either the depth of the water, or the height of the adjacent
land, or both. • In the failure of petrographic characters to persist
through considerable thicknesses, the Jurassic system of the central
province is in contrast with most of the systems of the Paleozoic.
In igneous rocks, the Jurassic system of the south and central
provinces of Europe is poor. Such rocks enter into the system in
western Scotland (Sky, Mull), and the date of their origin is about
-the close of the Middle Jura.
1 Geikie, op. cit., p. 1148.
2 Idem, p. 1157,
THE JURASSIC PERIOD. 77
Throughout much of western Europe, the Jurassic beds are still
nearly horizontal, but in the Jura Mountains, in the Alps, and other
mountains of the south central system of Europe, as well as in the
Caucasus, they are tilted and sometimes closely folded. Where they
have been undisturbed they are often unindurated. In the eastern
province the deformation of the beds is not great.
Extra-European Jurassic.
Arctic lands. — The Upper Jurassic formation is found in Spitz-
bergen, Nova Zembla, Franz Josef Land (Russian type of fauna),
over a large part of Siberia, and in the New Siberian Islands to the
north, in the Aleutian Islands which form the connecting link between
Asia and America, in Alaska, in some of the Arctic Islands of North
America, and in eastern Greenland. This distribution means a great
Arctic Sea in the Late Jurassic epoch, with two considerable dependen-
cies to the south — the one in Russia, the other, as we have already
seen in western North America. In all of the high latitudes where
the Upper Jurassic strata are widely distributed, the Lower Jura is
wanting, as far as known, and in most of them the Brown Jura
also.
Asia. — The Lias is not known in central Asia, but it occurs in Asia
Minor, north Persia, Assyria, the Himalayas, and Japan.1 The Middle
Jura, largely clastic and of terrestrial origin, is wide-spread in northern
Asia, some beds containing much carbonaceous matter. Marine Middle
Jura is known in northern India.2 The Upper Jura is known at vari-
ous points in Asia Minor, in the Himalayas, in Tien Shan, Japan, and
Siberia. It covers great areas in the basins of the Olensk, the Lena,
the Jana, the Yenesei, and the Obi Rivers,3 and in Kamtschatka, but
is not known in central Asia. The Jurassic strata, especially the
Upper Jurassic, are therefore widely distributed in Asia as in Europe.
Africa. — So far as now known, the marine Jurassic of this con-
tinent is confined to the northern and eastern coasts. Marine Lias is
known only in Algeria and western Madagascar; the middle and upper
parts of the system occur both in the north and in the southeast.
The western coast of India and the eastern coast of Africa, including
1 De Lapparent, op. cit., pp. 1084 and 1101.
2 Idem, p. 1142.
» Idem, p. 1233.
78 GEOLOGY.
Madagascar, seem to have been parts of the .same marine province at
this time.1
Australia. — The Lias is known both in New Zealand and Borneo,
but Australia was probably land during this epoch. The Middle Jura
is known in New Zealand, New Guinea, and in western Australia, where
clastic beds rest unconformably on much older rocks.2 In Queensland,
non-marine Jurassic formations are known. The rocks are largely
clastic and include valuable beds of coal.3
Central and South America. — The Lias is well developed in Mexico,
Peru, and the Bolivian Andes, Chili, and Argentina, and in the last-
named country it contains coarse conglomerates and volcanic tuffs.4
The Middle Jura occurs in Bolivia and Argentina, while the Upper Jura
is wide-spread in Mexico, and occurs in Chili and Argentina.
Coal.
Coal of considerable value is somewhat widely distributed in the
Jurassic formation. Besides that in the Lias of Hungary, it occurs
in the Caucasian region, Persia, Turkestan, southern Siberia, China,
Japan, and Farther India, in many of the islands southeast of Asia,
and in Australia and New Zealand. In the last-named country, the
coal-bearing formations are interbedded with marine strata, suggesting
considerable oscillations of level. In most of these countries, the
coal is Liassic. Outside of North America, it is probable that no
other system, except that of the Carboniferous, contains so large an
amount of coal as the Jurassic.
Geography of the Jurassic Period.
From the distribution of Jurassic strata, and from the study of
their fossils, it has been possible to draw many inferences concerning
the distribution of land and water during the period. From such
data, Neumayr has attempted to outline 5 in a general way the land
and water areas of that stage of the Jurassic period when the sea was
most wide-spread. One of the striking things shown by his map is
1 De Lapparent, op. cit., pp. 1178, 1205, 1236.
2 Idem, pp. 1084, 1101, 1145.
8 Geikie, op. cit., p. 1161.
4 Kayser, Geologische Formationskunde, p. 382.
5 Erdegeschichte, Vol. II, p. 336.
THE JURASSIC PERIOD 79
the great expanse of land in the tropical latitudes, and the great expanse
of sea in the Arctic regions. According to Neumayr's conjecture, the
late Jurassic expansion of the sea was one of the greatest known in
geological history, and the distribution of the land at the time of
the maximum extension of the sea was very different from that which
existed in the Lias, when there was a great expanse of land in the
Arctic latitudes.
Climate. — The testimony of fossils gathered in various parts of
the world is to the effect that the climate of the Jurassic period was
genial. In Europe, corals lived 3000 miles north of their present limit,
and saurians and ammonites flourished within the Arctic circle. Never-
theless, climatic zones were probably defined at that time.1 Corals
are unknown in the deposits of the great Arctic belt of Upper Jura,
and the detailed study of the faunas has led to the belief that three
more or less well defined zones were in existence. One is recorded
in the Jurassic beds of the Arctic belt; a second in the deposits of the
central European belt; and a third in the southern province of Europe,
and in the lands farther south.
There can be no doubt of the great differences in the faunas of
these different provinces, but it is not certain that the differences
were due wholly or even mainly to climatic influences.
It should perhaps be noted that there are conglomerates in the
Lias of Scotland which have been conjectured to be glacial,2 but there
is no proof that this was their origin.
Close of the Jurassic in Europe. — The close of the Jurassic appears
to have been marked by a somewhat widespread emergence. In the
central province, this disturbance appears to have begun before the
close of the Jurassic, for the latest beds (Purbeck) referred to that
period in England are unconformable on beds lower in the series.
Similar changes are known to have occurred in late Jurassic time in
some other regions; but the Upper Jurassic and the Lower Cretaceous
beds are in many regions so closely associated as to show that no change
of continental dimensions intervened between them. Great deformative
movements seem to have affected no part of Europe at the close of
the period.
1 Neumayr, loc. cit., p. 331.
3J. Geikie, Outlines of Geology.
80 GEOLOGY.
THE JURASSIC LIFE.-
As the Jurassic seems to have been mainly a period of sea extension,
correlated with a base-leveling of the land, the marine life again assumes
a place of leading importance. At the same time the land life, though
suffering somewhat by the limitation of its territory during the stages
of sea transgression, was favored by the subdued attitude of the land
and the genial climate. The frequent shif tings of land- and sea-areas,
without involving great topographic relief or severe climatic states,
conduced to changes in the forms of life which were on the whole pro-
gressive and expansional, though necessarily retrogressive in particular
phases.
The Marine Life.
It will be recalled that a markedly expansional stage of epiconti-
nental sea life had set in toward the close of the Trias. This held
on into the Jurassic, fluctuating with the sea expansions and retro-
gressions, but in general progressing until it reached a climax in the
latter part of the period, when the sea attained the limit of its remark-
able transgression upon the land. Later there was a measurable
decline closing the period. As already indicated, this faunal progress
is far less well revealed in North America than hi Europe and Asia,
and a general sketch drawn chiefly from the Old World may well pre-
cede a special statement of the more meager American development.
The great features of the marine life lay in (1) the continued domi-
nance of the ammonites among the invertebrates, (2) the rise of the
belemnites, (3) the abundance and modernization of the pelecypods,
(4) the rejuvenation of the corals and crinoids, (5) the marked develop-
ment of the sea-urchins, (6) the introduction of crabs and modern
types of crustaceans, (7) the prevalence of foraminifera, radiolarians
and sponges, and (8) the change in the aspect of the fishes, while
(9) all were dominated by the great sea-serpents evolved from the
land-reptiles of the Trias.
(1) The ammonites which, in certain respects, reached their cli-
max in the later stages of the Trias, were still the master type among
invertebrates, and were represented by many beautiful forms. They
deployed on ascending lines in some cases, and retrogressive lines in
others. There were cases of erratic and senile development, reflected
THE JURASSIC PERIOD.
81
by uncoiling, spiral coiling, and other departures from the normal
lines of the order, presaging an episode of " sporting " and retrogression
in the next period, to be followed by extinction; but, despite these
adverse foreshadowings and some notable reduction in diversity,
FIG. 357. — A GROUP OF JURASSIC AMMONITES: a-b, Coroniceras bisulcatum (BrugX
a lateral and ventral view of one of the Arietidce; c, Deroceras subarmatum (Young)
d, Perisphinctes tiziani (Oppel); e, Reineckia brancoi Steinm.
the ammonites were yet in the climacteric stage of their luxuriance
and beauty. They had well-nigh reached the limits of attainment
in such features as close coiling, complexity of sutures, ornamenta-
tion and some other characteristics. The continued expansion of
the sea gave them still a widening field over which they spread them-
82
GEOLOGY.
selves in successive
FIG. 358.— The internal
shell of a belemnite,
restored; the lower,
solid, conical portion,
the part most fre-
quently preserved, is
the rostrum or guard ;
the middle portion is
the phragmocone,
which is a diminutive
chambered shell with
septa, siphuncle, and
protoconch as in the
older tetrabranch or-
der; the upper part is
the prostracum, which
corresponds to the
" pen " of the living
cuttle-fishes.
of both continents.
generations with unusual breadth and uniformity,
and marked with peculiar fidelity the successive
stages of Jurassic marine history. At least thirty
faunal zones have thus been distinguished in
Europe, and recognized in large degree in southern
Asia (Cutch).
(2) The ammonites and their predecessors, the
ceratites, goniatites and orthoceratites, were tetra-
branchs and had external shells, but there had
been introduced in the Trias the dibranchiate
form which had internal shells, if any at all, and
these rose to prominence in the Jurassic with ex-
traordinary rapidity in the form of belemnites.
The first known of the cuttlefishes (sepeoids) also
appeared at this time. The belemnites were
cephalopods of general cuttlefish aspect, usually
represented in the fossil state by their internal
shell or " pen/' as illustrated in Fig. 358. The
fact that the phragmocone had the characteristic
features of the chambered shells of the tetra-
branchiates in a seemingly aborted and useless
form, has naturally suggested that the belemnites
were their descendents, but this view is not en-
tirely without difficulties. The belemnites rose so
rapidly that in the course of the period they
almost came to rival the ammonites, and were
almost as characteristic of the successive stages
of deposition.
(3) The pelecypods also flourished during the
period, and took on a markedly modern aspect,
the oyster family taking the lead, the Ostrea itself
being common. Among the more notable genera
were the thick-shelled, odd-shaped Trigonia,
Gryphcea, Exogyra, and Ostrea, and the smooth,
thin-shelled Aucella of world-wide distribution
(Fig. 359). Certain species of Aucella were es-
pecially characteristic of the northern provinces
THE JURASSIC PERIOD.
S3
The gastropods were abundant in some quarters but singularly
absent in others, and among them were some genera still living.
(4) Suggestive of shallow clear seas was the reappearance of corals
and crinoids in great abundance in the latter part of the period. The
modern (Hexacoralla) type of corals had come into dominance, and
gave rise to reefs so abundant and so wide-spread, particularly in the
FIG. 359. — A GROUP OF JURASSIC PELECYPODS: a, Trigonia navis Lam.; b, Gryphcea
arcuata Lam.; c, Ostrea deltoidea Sby.; d, Exogyra (Ostrea) virgula D'Orb.; e,
Aucetta mosquensis Keys.
European seas of the Middle Oolitic stage, as to give the name Corallian
to the epoch, and Coral Rag to the formation (Fig. 360, a and b). This
was a feature of the last expansive stage of the period, and seems to
mark the climax of base-leveled, vegetal-mantled lands, with minimum
in wash of silt correlated with a wide, thin sheet of epicontinental
water.
The crinoids again rose to prominence, though their diversity of
forms was not great. They departed from Paleozoic forms in a marked
84
GEOLOGY
diminution of the calyx, and a remarkable extension and subdivision
of the arms (Fig. 360, d). Unattached crinoids were present. The
FIG. 360. — JURASSIC COELENTERATA AND ECHINODERMATA: a, b, Thamnastrcea pro-
lifera Becker, a complete corallum, and the lateral surface of a costal septum
enlarged; c, Thecosmilia trichotoma (Goldf.); d, Pentacrinus briareus Mill; e,
Cidaris coronata Goldf.
majority of the Jurassic crinoids were undoubtedly shallow- water
forms, as most of the Paleozoic types had been; but there is evidence
THE JURASSIC PERIOD. 85
that deep-water species had begun to appear, leading toward the present
dominant but not exclusive habit.
(5) The long, slow evolution of the echinoids in the Paleozoic era
was succeeded in the late Trias by the beginning of a rapid and strong
evolution in the form of sea-urchins, and these were now on their
rapidly ascending curve which reached its climax in the early Tertiary.
The Jura was especially rich in the so-called " regular " sea-urchins
(Cidaroida and Diadematoida) , The cidarid type, with large club-
shaped spines, \vas characteristic (Fig. 360, e).
(6) The crustacean dynasties of the Paleozoic, the trilobites in
the sea and the eurypterids in the land waters, now quite extinct,
were succeeded by the decapods which rose to a moderate and pro-
longed ascendency. The prawns and lobsters (Macroura, long-
tailed decapods) were the earlier division, and the most numerous
in the Jura, but the first of the known crabs (Brachyura, short-tailed
decapods) appeared in this period. The macrourans seem to have
especially frequented embayments and protected locations near the
land or perhaps within the land, such as are represented in the famous
Solenhofen deposit, where terrestrial, fresh- water, and marine forms
are preserved in the same sediments. It is not improbable that the
macrourans, then as now, had representatives in the terrestrial as well
as marine waters.
(7) Sponges were very prolific and well preserved, and give char-
acter to the Spongiten Kalk of the Upper Jura. Foraminifera flourished
and were well preserved, a foreshadowing of their great importance
in the Cretaceous period. Radiolarians furnished, by their siliceous
tests, the material for the flints that abound in certain parts of the
system.
The brachiopods retained the Terebratula-Rhynchonella aspect they
had assumed in the Trias, but were no longer a leading feature in the
fauna except locally.
(8) A marked change in the aspect of the fishes had set in during
the Trias, and was continued with further development in the Jura.
The crossopterygians and dipnoans were greatly reduced; the sela-
chians continued with undiminished numbers; the skates and rays
began their modern career by appearing in two typical families (Squati-
nidce, Fig. 361, and Rhinobatidce) ; the Chimceridce, the existing family
of sea-cats or spook-fishes, made its appearance and developed notably
86
GEOLOGY.
(Fig. 362). The forebears of the living gar-pikes and sturgeons took
precedence in numbers; the forerunners of the modern Amia (Fig.
363,) were an important factor, and the
initial forms of the bony fishes (teleosts),
the dominant existing type, made their
appearance. The peculiar persistent family,
Ccelacanthidce (Fig. 364), attained its maxi-
mum development. The earliest repre-
sentatives of the remarkable pycnodonts
came in with the early stages of the period.
The new aspect was markedly more
modern than that presented at the close
of the Paleozoic.
(9) It was noted under the Trias that
certain land-reptiles went down to sea,
and introduced a new phase of vertebrate
mastery over the deep. From what has
just been said of the fishes, it appears
that, while doubtless suffering much from
the new dynasty, they maintained a
notable abundance and variety, and it
will be seen later that they outlived the
invading race, and resumed their former
place of dominance, in large degree, though
FIG. 361. — A Jurassic skate, . „
Squatina speciosa, about two- never Wholly.
hofen, Bavaria.
. Marine «ptiles.-0f the four groups
(A. Smith of reptiles which went down to the sea,
the thalattosaurians, ichthyosaurians, ple-
siosaurians, and thalattosuchians, the first had apparently become wholly
extinct, while the last made its first appearance near the close of the
period. Of the other two, the ichthyosaurs, as the name implies, were the
most fish-like in appearance. They reached their highest development
in this period, and from the abundance and wide distribution of
their remains, it appears that they were very prolific, and probably
traversed every sea. Their adaptation to aquatic life is shown in
the complete transformation of the lirnbs into paddles (Figs. 365 and
366), in the reduction of the outline of the body to ichthyic lines
and proportions, in the sharp bending down of the vertebrae of the
THE JURASSIC PERIOD. 87
tail near its extremity for the support of a remarkable caudal fin, in
the long snout, set with teeth adapted to seize and hold slipping prey,
FIG. 362. — A Jurassic spookfish or chimseroid. Squaloraja polyspondyla, one-fourth
natural size; from the Lower Lias, Dorsetshire. (Restored by A. Smith Wood-
ward.)
but not to masticate it, in the protection of the eye by bony plates,
and, interestingly enough, as it would appear from cumulative evidence,
in the development of a viviparous habit that freed them from the
necessity of returning to land to deposit their eggs, as do the sea-going
turtles and crocodiles.
The ichthyosaurs became not a little divergent in form, habit and
food, and, in the latter part of the period, developed forms (Ophthal-
mosaurus, Baptanodori) in which the teeth had been greatly reduced
in size; some indeed were for a long time supposed to have been
quite toothless. That their food consisted in part of invertebrates
is evident from the occurrence of the remains of such animals mingled
FIG. 363. — A Jurassic forerunner of the modern Amia, Eugnathus athostomus, about
one-seventh natural size, from the Lower Lias, Dorsetshire. (A. Smith Woodward.)
with the fossil contents of the stomach, and it is not unreasonable to
suppose their food was largely formed of soft -bodied animals, per-
88
GEOLOGY.
haps the shelless cephalopods, whose advent has been noticed. The
remains of 200 belemnites have been found in a single stomach. There
FIG. 364. — A Jurassic coelacanth, Undina gulo, a crossopterygian, about one-seventh
natural size; the outline of the air-bladder is shown just back of the gills and under
the axis. (Restored by A. Smith Woodward.)
were small as well as large forms of ichthyosaurs, some of the latter
reaching 30 feet or more in length.
Descended from a quite different stock, the plesiosaurs adapted
themselves to sea life in their own fashion (Fig. 367). Instead of
acquiring the flowing lines of a fish, the body took on a form more
FIG. 365. — Photograph of Ichthyosaurus quadriscissus Quenstedt, showing outline
of paddles, fins, and body, as well as the skeleton. From the Lias of Wiirtem-
berg, from specimen in Carnegie Museum. (Per kindness of Director Holland.)
like that of a turtle, while the neck was very elongate, giving rise to
the epigrammatic description "the body of a turtle strung on a snake/'
The earlier representatives, the nothosaurs, were but partially aquatic,
while the true plesiosaurs were wholly so. The limbs of these latter
were developed into paddles rather than fins, and were sometimes
more than six feet long. Locomotion seems to have been chiefly
THE JURASSIC PERIOD.
89
dependent on the paddles, though a fin-like adaptation of the tail is some-
times observed. Their movements were hence probably slow. The
FIG. 366. — Outline and skeleton of Ichthyosaurus quadriscissus. (After Jaekel.)
elongation of the neck was variable, some even being short, while
the more typical forms were very long. The vertebra of the neck
ranged from 13 to 76, the last being more than any other animal, living
or extinct, is known to have possessed (Williston). The neck appears
not to have been as flexible as familiar illustrations have represented
it, nor were the jaws separable and extensible as in the case of snakes.
FIG. 367. — Skeleton of Plesiosaurus dolichodeirus Conyb. (Restored by Conybeare.)
This implies that they either lived on small prey, or tore their food
to pieces before swallowing. They were doubtless formidable foes of
the smaller sea life, but probably not of the larger. Like the ichthyo-
saurs, they were covered with smooth skins unprotected by scales or
scutes. They ranged from 8 to 40 or more feet in length. They had
the singular habit of swallowing and retaining in the stomach,
small stones, " gizzard stones," the purpose of which has given rise
to much speculation and discussion. As some of these stones must
apparently have been picked up far from the final resting-place of
the skeleton, it is inferred that the plesiosaurs were wide rovers of
the seas. Williston regards them as solitary in habit, while he thinks
the ichthyosaurs were gregarious, somewhat like the dolphin. The
distribution of the plesiosaurs seems to have been world -wide, and
the species were numerous.
90 GEOLOGY.
The suborder of crocodilians, to which the name Thalattosuchia
has recently been applied by Fraas, made its appearance during the
latter part of the period, but enjoyed only a brief existence. These
truly marine crocodiles had undergone a remarkable adaptation to
sea life, from the land or fresh- water forms (Fig. 368). They were very
FIG. 368. — Restoration of a Jurassic crocodilian, Geosaurus suevicus. (Fraas.)
fish-like in appearance, were wholly covered with a bare skin, and the
long tail terminated in a large fin, like that of the ichthyosaurs. The
eyes were protected by sclerotic plates, and the fore limbs were short
and quite paddle-like. The hind limbs, however, were only slightly
modified from the land type, perhaps due to the recurring necessity
of visiting the shores for depositing and hatching their eggs.
True marine turtles, so characteristic of the Cretaceous, had not
yet appeared, though before the close of the period a number of forms
had arisen presenting a strange admixture of characters peculiar to
fresh- water and sea turtles (Thalassemydce).
The American marine faunas. — The marine life of Jurassic times is but feebly
represented in the American strata, no representatives at all having been found
on the eastern coast. There was doubtless a sea-shelf on that border which
was occupied by its appropriate fauna, but it has been buried by later deposits.
In the Pacific region, marine life occupied nearly the same districts as in
Triassic times, but no consecutive series of faunal evolution has yet been worked
out. Present imperfect evidence points to two faunal provinces, one of which
succeeded the southern or Nevada-California province of the Trias, and the
other the north Pacific province. The fauna of the former ranges from the
lower to the upper division, that of the latter represents the later Jura only.
The fauna of the earliest epoch (Lias) does not appear to have been derived from
THE JURASSIC PERIOD. 91
the Triassic fauna which occupied the same region previously. It has the aspect
of the European Liassic fauna, and of a similar fauna found in the island of Timor,
between Java and Australia, and also in Argentina.
As the successive horizons of the European Jurassic are defined most char-
acteristically by their ammonites,1 the most instructive element of the fauna of
this stage in the Nevada-California-Oregon province was the ammonite family
Arietidce, represented by Arnioceras nevadanum, A. humboldti, A. woodhulli,
Coroniceras daytoni, and Vermiceras crossmani. The belemnites are represented
by a single form. Several genera of pelecypods were present (Goniomya, Lima,
Pecten, Pinna, Plicatella, Pleuromya, and Pholadomya) ; a Turbo represented
the gastropods, a Cidaris the echinoderms, and a Glyphcea the crustaceans.
This list appears very meager when compared with the nearly 250 genera and
more than 1600 species enumerated by Etheridge from the corresponding
European fauna. How this fauna had communication with central Europe,
Timor, and South America is undetermined. A route via the " central Mediter-
ranean Sea" of Neumayr has been suggested,2 and a route from Timor, via New
Zealand and Antarctica to South America, and thence by the coast to California,
may be speculatively offered as involving not improbable geographic connec-
tions.
The American fauna of the Middle Jurassic epoch is not sufficiently ample,
as now known, to clearly indicate its relations to foreign faunas, but it has the
aspect of the central European fauna (J. P. Smith). Like the preceding, it
is essentially a group of molluscan forms in which the pelecypods greatly out-
number all other species. Several of the preceding genera were present, and
several new ones were added (Modiola, Mytilus, Pinna, Pteroperna, Gervillia,
Lima, Ctenostreon, Pecten, Pholadomya, Trigonia, Opis, Inoceramus). The
cephalopods embraced ammonites (Sphceroceras, Grammoceras, and Perisphinctes)
and a belemnite. The gastropods were represented by a large Nerinea and the
brachiopods by Terebratula and Rhynchonella.
In the fauna of the Upper Jurassic, the molluscan monotony is relieved by
the introduction of several species of corals which are so similar to European
species of the Corallian formation as to imply equivalence with that horizon.
This is confirmed by the species of pelecypods, by the cephalopod Rhacophyllites,
and by the gastroped Chemnitzia. In other beds of the series, a more consider-
able group of pelecypods (Aucella, Avicula, Amusium, Trigonia, Entolium, Oxy-
1 " These highly specialized faunas, as has been pointed out by several of the most
distinguished paleontologists in Europe, must have been extremely sensitive to the
influences of the changes of their surroundings in passing from one geological horizon
to another, and have recorded these mutations in their own organizations. Even
the encyclopedic Quenstedt continually expresses his satisfaction in turning from
the uncertain indications afforded by the more generalized structures of other mollusca
to the decisive chronologic evidence usually given by the fossils of this group." Hyatt,
Geology of the Taylorville Region, Bull. Geol. Soc. Am., Vol. Ill, p. 404.
2 For a discussion of this and related subjects see " Mesozoic Changes in Fauna!
Geography," bv James Perrin Smith, Jour Geol., Vol. Ill, 1895, pp. 369-384.
92 GEOLOGY.
toma) and of cephalopods (Cardioceras, Perisphinctes, Olcostephanus, OEcotraustes
Reineckia, Macrocephalites) together with other forms occur.
At a higher horizon there appear significant species of Aucella of the types
represented by A. pallasi and A. brauni, associated with Avicula and Amusium,
and the ammonites Cardioceras (of the group C. alterinous], Perisphinctes, Olcos-
tephanus, and (Ecotraustes , which belong to the northern fauna of Russia (the
"boreal" of Neumayr), while the coralline group named above appears to be,
allied to the more southern fauna of Europe. From the northern alliance it
is inferred that at some time in the closing stages of the Jurassic period, rather
free communication was established between the north Eurasian province and
the western shore tract of America, and that north Eurasian species migrated
down the American coast as far as Mexico, where Nikitin has identified the
"boreal" fauna in San Luis Potosi. As the great Jurassic transgression of the sea
was especially a northern movement, it is quite consistent that the northern
fauna should thus invade the western coast tract of America. The same fauna
spread south to the northern side of the Himalayan province, while the fauna
of the Cutch region on the Bay of Bengal still retained the central European
aspect, as did also that along the east coast of Africa (Mombassa).
The northern and more interior province. — The northern American province,
embracing parts of Dakota, Wyoming, and other states (Fig. 348) , with northerly
connections not yet worked out, bore a fauna of still more pronounced northern
affinities. A fine group of ammonites nourished in Wyoming and the Black
Hills region (Cardioceras, Cadoceras, Quenstedioceras, and Neumayria) , all of them
peculiar to the Callovian and Oxfordian horizons of the upper Jurassic (Hyatt.1)
The species are not the same as those of the California district, which implies an
absence of free inter-communication. Belemnites were well represented (Fig.
369, c) and pelecypods (Ostrea stringileculia (Fig. 369, h) , Camptonetes bellistriatus
(Fig. 369, d), Gryphcea calceola, Tancredia bulbosa, Pecten newberryi, Saxicava
jurassica, Mytilus whitei (Fig. 369, e), predominated. Curiously enough, no
gastropods have yet been found in this province. The ancient genus Lingula
(Fig. 369, f) had a diminutive representative, as did also the familiar Rhychonella
(Fig. 369, i). A crinoid and a starfish represented the echinoderms,,
It is noteworthy that Aucella, one of the most characteristic fossils of the
California province, has not yet been found in the Dakota province. It is found
in Alaska, in the Aleutian Islands, and in Russia. It was formerly supposed
that the Aucella migrated from Eurasia to America, because, as then known,
it ranged lower in Europe; but more recent investigations indicate that it
occurred quite as early in America as in Russia, and earlier than in England.
If the migrating tract between the Californian province and Asia lay along the
Pacific border, while the migrating tract between the Dakota province and Asia
lay in the Mackenzie basin and along the Arctic border, the two provinces only
coming into free communication far to the westward, it is not difficult to under-
1 Jura and Trias at Taylorville, California, Bull. Am. Geol. Soc. Am., Vol. Ill,
p. 410.
THE JURASSIC PERIOD.
93
stand how the Aucella, with favoring currents and temperatures, could migrate
from California into Russia without migrating into the Dakota province. On
the other hand, species migrating from Russia might easily take either the Pacific
route to the Californian provinces, or the Arctic-Mackenzie route to the Dakota
province. If this were the geographical configuration, future research will
probably show that faunas originating on the Pacific coast in America had a
distribution like the Aucella, and that faunas originating in the Dakota province
had a distribution through the Arctic regions and westward into northern Russia,
FIG. 369. — CEPHALOPODS: a, Cardioceras cordiformis M. and H.; b, Neumayria henryi
M and H. ; c, Belemnites densus M. and H. PELECYPODS: d, Camptonectes belli-
striatus Meek; e, Mytilus whitei Whitf.; /, Grammatodon inornatus M. and H ;
g, Pseudomonotis curta (Hall) ; h, Ostrea strigilecula White. BRACHIOPODS : i, Rhyn-
chonella gnathophora Meek; /, Lingula brevirostra M. and H.
rather than into the California province, while Russian forms entered both prov-
inces, and the South Asian forms entered only the Californian province as a rule.
In rare cases, species from one American province might reach the other via the
junction of their migrating tracts in Asia, or wherever it may have been. At
the time of maximum transgression of the sea, more direct communication between
the American provinces might naturally have been established. Present
knowledge of the Jurassic fauna of the Arctic islands is too scant to throw much
light upon this matter. Ammonites macdintocki, closely related to A. concavus,
has been found on Prince Patrick Island, and A. wosnessenski, A. biplex, Belem-
nites paxillosus, and Pleuromya unioides at Cook's Inlet.1
The Jurassic fauna of the Dakota province belongs to a late epoch of the
period, which implies perhaps that the Arctic sea did not extend its elongate
arm so far south until near the time of the great stage of sea transgression of
which it constituted one of the striking features.
1 Dana's Manual, p. 760.
94 GEOLOGY.
The geographical conception suggested by the distribution of the Aucella
is perhaps strengthened somewhat by the occurrence of corals in the California
province, and their absence from the Dakota province. Neumayr has shown
that corals were essentially absent from the northern Russian province, while
they abounded in the central and southern European provinces. From this
more southerly habitat, their distribution to the Indian province and thence
to California, would be consistent with their absence from the Dakota province,
if the route along the Pacific sea-shelf were isolated from the Dakota province,
as suggested. At the same time, it is not impossible that the former continental
tract which connected Asia with Australia and New Zealand, of which there is
abundant evidence, may have been extended so as to connect with South America
by way of the Antarctic land, from which Australia and South America are
separated, respectively, by moderate distances only, and by sea-depths about one
third the usual abysmal depths. This would best harmonize with the distribu-
tion of the Arietidce from Europe to Timor on the line of the old continental
extension between Java and Australia, and thence to the Argentine Republic
and to California, where Hyatt finds evidence of their progressive advance from
the south to the north. But these suggestions must be held lightly until sup-
ported by more evidence.
THE LAND LIFE.
I. The vegetation.
The land vegetation of the Jurassic was little more than a con-
tinuance and enrichment of that of the late Triassic, with slow prog-
ress toward living types, cycadeans, conifers, ferns, and equiseta
being still the leading forms, slightly more modernized, but not radi-
cally changed.1 The cycadeans (Bennettitaks and Cycadales) were
perhaps the most distinctive forms, constituting this the climax of
the " age of cycads," but the conifers showed the more notable moderni-
zation. They embraced yews, cypresses, arborvitas, and pines, all
of which assumed a somewhat familiar aspect, though the species
were all ancestral. The ginkgos also played a somewhat important
role.
An interesting feature of the European record is the rather fre-
quent occurrence of land plants in marine beds, which not only implies
that many trunks, twigs, leaves, and fruit were floated out to sea, but
that the landward edges of the deposits escaped serious erosion, a
1 For a comprehensive paper on the Jurassic plants of the United States, with
descriptions and illustrations by Lester F. Ward, see 20th Ann. Rept. U. S. Geol.
Surv., 1898-99, pp. 334-430.
THE JURASSIC PERIOD. 95
phenomenon which grows more common as the deposits become more
recent, but is especially characteristic of stages of base-level and advan-
cing seas. It is made the more interesting by the presence, in the
same beds, of many land insects that suffered a similar fate. Not a
few of them were wood-eating beetles, thus giving a hint of the nature
of the battle of life, implying that the plants found enemies not only
in wind and storm, but in predaceous foes without and within. In
the closing stages, the land was extended, which should in itself have
been favorable to an expansional development of plants, but such
extensions of the land are so liable to be attended by adverse climatic
and topographic changes, that no safe inferences can be drawn except
from the actual record, which is rather scanty. In the heart of the
period, the distribution of genera and even of species was wide, both
in longitude and latitude, implying uniformity of conditions. Some
tendency to provincial limitation appears, as in the apparent restric-
tion of Ptilophyllum to India, Gingkodium to Japan, and the Abietince
to northern Eurasia. The last has been made a basis for the suggestion
that a climatic differentiation had begun by the cooling of the northern
regions, a suggestion based on the assumption of a universal warm
climate in early times, sequent on a molten globe. The flora should
probably rather be interpreted as indicating that the period was one
of the series of periods marked by the mild, uniform climates attend-
ing base-level conditions and sea extension, which alternated with
periods of more diversified and occasionally severe climates.
II. The Land Animals.
Classificatory difficulties. — The discussion of the land animals of
the Jurassic Period is embarrassed by a systematic infelicity in the
accepted methods of limiting " Periods." Technically, periods are
founded essentially on marine formations and marine life ; and properly
so, because these have given by far the best record, and most closely
reflect the deformative movements that lie back of life changes. An
ideal marine period consists of a great advance of the sea upon the
continent, attended by an expansional evolution of the shallow- water
life, followed by a withdrawal of the sea, attended by a restrictional
evolution of the life. The ideal division between such periods is obvi-
ously the time of maximum withdrawal, when the fauna developed in
the expansional stage is being reduced to its lowest terms by restriction,
96 GEOLOGY.
and the basis of a new fauna is being laid by severe natural selection.
But ideally, the expansions and restrictions of the land life are pre-
cisely reciprocal to those of sea life, and hence the centers of these
normal land periods, are coincident with the dividing points of the
marine periods, as illustrated in Fig. 370.
When the land period is very pronounced, as after a great deform-
ative movement, it is apt to be seriously affected by topographic and
climatic agencies, and may not be truly expansional in its life evolu-
tion, although it may be revolutionary. Such an instance is the
Permo-Triassic land period, when aridity and glaciation probably
more than offset the increase of land-area in their influence on organic
productiveness. But when the deformative movement did not reach
such lengths, and a favorable climate and topography accompanied
an increase of land -area, there should naturally be an expansional
evolution of the land life. At such times also, the mild deformations
FIG. 370. — A sketch illustrating the reciprocal relations of ideal land periods and
sea periods.
should have developed shallow lodgment -basins, and areas of aggra-
dation favorable for a good record of the land life. These theoretical
sequences seem to have been realized in the transition from the Jurassic
to the Comanchean or Lower Cretaceous , The Purbeckian, usually
regarded as the closing stage of the European Jurassic, and the Wealden,
usually regarded as the opening stage of the Lower Cretaceous of
Europe, though they bridge the dividing line of the marine periods,
really constitute together the heart of an important period of terrestrial
life development. On the American continent the Como, Trinity, and
Lower Potomac horizons stand in the same relations. From this stage
dates, as we shall see, the initial deployment of the angiosperms, one
of the most important vegetal revolutions in geologic history. In
this stage also there was a very marked deployment of the great reptiles.
It is inconsistent with a normal treatment of reptilian deployment
to dissever it along the lines of division that are most appropriate
to the marine life, natural as that is in its own field, and best as a gen-
THE JURASSIC PERIOD. 97
eral scheme of division. A division at this point is made particularly
infelicitous, so far as the land life is concerned, because the American
beds of this stage, which are richest in reptilian remains, the Como or
Morrison, have usually been referred to the Jurassic (Pur beck epoch).
This reference is now questioned, and they are regarded by many,
perhaps by most investigators, as Lower Cretaceous (Wealden epoch),
while by some, a portion of the beds in question are regarded as
Jurassic and the rest as Lower Cretaceous (Comanchean). This adds
grave artificial difficulties to the natural ones. It seems best, there-
fore, to follow the leadings of natural evolution, and to consider the
reptilian deployment of the Jura-Comanchean land epoch as an essen-
tial unit, with some parenthetical guards against erroneous references.
The Jura-Comanchean development of the land vertebrates. — The
anomodonts and some other ancestral reptilian races had followed the
stegocephalians into retirement, while other early races lived on in
secondary importance. The great feature of the closing Jurassic and
opening Comanchean was the marvelous development of the saurian
group, which made this the central stage of the " age of reptiles."
The dominance of the dinosaurs. — The dinosaurs in particular
attained remarkable size and diversity, and their dominant species were
easily lords of the reptile horde. They deployed not only along the
carnivorous line (Theropoda) which had appeared in the Trias, but also
on three herbivorous lines (Sauropoda, Ornithopoda, and Stegosauria).
Of the carnivores, one of the most typical was Ceratosaurus nasicornis,
from the Como beds, whose general aspect, shown in Fig. 371, illus-
trates the attitude and proportions of the order. The fore limbs seem
to have been used chiefly for seizing and holding prey, and rarely for
walking, the animal's pose being facilitated by hollow bones. The head
was relatively large, an unusual character for a race among which small
heads and diminutive brains were the fashion of the day. Not all
the theropods, however, were gigantic; there were small leaping forms,
like Compsognathus, not larger than a rabbit.
The herbivorous dinosaurs (Stegosauria, Sauropoda, Ornithopoda1)
first became known in this system, but their development was so ex-
1 For monographic treatment see Dinosaurs of North America, O. C. Marsh, 16th
Ann. Rept., U. S. Geol. Surv. The three suborders there recognized are Theropoda,
Sauropoda, and Predentata, Ornithopoda and Stegosauria being regarded as divisions of
Predentato.
98
GEOLOGY.
traordinary that they soon outranked the carnivorous forms both in
size and diversity. The sauropoda were generally massive animals,
with sub-equal limbs and the quadruped habit. Among these, Bronto-
saurus (Apatosaurus) attained the extraordinary length of 60 feet
FIG. 371 . — A carnivorous dinosaur, Ceratosaurus nasicornis, about TV natural size,
i.e. length about 17 feet; from the Como beds, Colorado. (Restoration of skele-
ton by Marsh.)
and possibly more, taking rank as one of the largest of known land
animals (Fig. 372). This enormous creature was characterized, never-
theless, by weakness rather than strength. The general organization
was unwieldy; the head was very small relatively, the brain having
less diameter than the spinal cord. " The task of providing food for
so large a body must have been a severe tax on so small a head." The
inconvenience of its bulkiness was perhaps relieved by an aquatic
habit. From the fact that its skeleton is sometimes found in a nearly
complete and orderly state, it has been inferred that the creature was not
infrequently the victim of its own massiveness, and lost its life by
sinking in some soft, treacherous shoal. This colossal animal may be
taken as illustrating the point at which bulk becomes a burden, and
as signalizing an approach to the limit of evolution in the line of size.
Even larger than Brontosaurus, and the largest of all known dinosaurs,
was Brachiosaurus, of which the femur measured more than two meters
THE JURASSIC PERIOD.
99
in length (80 J inches).1 There
were several other genera of similar
nature and of bulk only inferior
to these monsters. The tribe was
most abundant and most special-
ized in America, which was doubt-
less its place of origin; but some
European forms (notably Cetio-
saurus of England) were so closely
related as to be regarded by some
as generically identical.
The typical ornithopod (bird-
footed) dinosaurs were bipedal in
habit, much as the carnivores were.
On the hind limbs there were
usually only three functional toes,
so that they left a bird-like track ;
the fore limbs, however, had five
digits. Camptosaurus, known both
from America (Morrison beds) and
Europe, and nearly related to the
European Iguanodon of the Weal-
clen, was one of the largest of the
ornithopod dinosaurs, measuring
about 30 feet in length, and about
18 in height, in the walking
posture. Other related forms,
like Nanosaurus or Laosaurus,
were not more than three or four
feet in height and were the small-
est of this group known.
The stegosaurs, like the sauro-
pods, were quadrupedal in habit,
and, like them, had solid bones.
They were curiously armored, and
formed a group of very remarkable
creatures that frequented England
1Riggs, Amer. Jour. Sci., 1903
100
GEOWGY.
and western America. While they were less gigantic than the sauro-
pods, they found compensation in protective plates, spines, and similar
modes of defense. The Stegosaums of Colorado and Wyoming (Como
beds) was one of the most unique, (Fig. 373.) The remarkably diminu-
FIG. fflS—Stegosaurus, an armored dinosaur of the Jurassic. Interpreted by Charles
R. Knight. (Lucas' Animals of the Past. By permission of the publishers, Messrs.
McClure, Phillips and Company.)
tive head and small brain imply a sluggish, stupid beast, depending
for protection on its bulk and armor.
The prevalence of so many of these dinosaurs on the North American
and the Eurasian continents seems to imply that these lands were
connected, and that they were the chief dinosaurian home, though dino-
saurs have been identified in South Africa in beds probably Triassic.1
Other reptilians. — The true rhynchocephalians first made their
appearance during the Jurassic, in forms scarcely distinguishable
from the living Sphenodon, but they played no conspicuous role. Tur-
tles became abundant, though distinctively marine forms had not yet
appeared. The crocodilians, though still retaining the primitive
type of biconcave vertebra?, became differentiated into the marine
thalattosuchians, the long-headed, gavial-like teleosaurs, and the
short-headed, crocodile-like types which probably found much of their
1 Broom, The Geology of Cape Colony, by A. W. Rogers, 1905, p. 244.
THE JURASSIC PERIOD. itil
food in the small mammals and reptiles frequenting the shores of the
estuaries. Primitive lizards were doubtless abundant, but because of their
terrestrial habits and small size, very few if any have been discovered.
The advent of aerial life; the pterosaurs. — It has already been
noted that the crowding of the land may have led some reptiles to
take to the sea. The same influence may have forced others to take
to the air, and thereby escape the monsters of the swamps, jungles,
and forests. Whatever the cause, the most unique feature of the
period was the development of flying reptiles. Appearing at the
very close of the Trias in a few yet imperfectly known forms, they
presented themselves at the very opening of the Jurassic period (Lower
Lias), as fully developed flying animals in the genus Dimorphodon,
and later formed a diversified group embracing long-tailed forms, as
FIG. 374. — A flying saurian, Rhamphorhynchus phyllurus Marsh, in which the wing
membranes are preserved; about one-fourth natural size. The rod-like bones
that support the wing membranes are the extended fifth phalanges; the caudal
oar and the elongate skull are also well shown. From the lithographic stone at
Eichstadt, Bavaria.
Rhamphorhynchus , and short-tailed forms, as Pterodactylus. With little
doubt they sprang from some agile, hollow-boned saurian, more or
less remotely akin to the slender, leaping dinosaurs. Between the
ponderous brontosaurs (Fig. 372) and the airy pterodactyls (Fig. 374),
the Jurassic suarians present the strangest of contrasts. The Jurassic
pterosaurs were small, but tneir successors attained a wing-spread of
nearly a score of feet. They were curiously composite in structure
and adaptation. Their bones were hollow, their fore limbs modified
102 GEOWGY.
for flight, their heads bird-like, and their jaws set with teeth; but tooth-
less forms at length appeared. They were not. adorned with feathers,
but provided with membranes stretched, in bat-like fashion, from the
fore limbs to the body and hinder limbs, and serving as organs of
flight (see Fig. 375). The fifth, or as some paleontologists believe,
the fourth, digit was greatly extended, and served as the chief sup-
port for the whig membrane. The sternum was greatly developed,
implying that they had true powers of flight, a conclusion sup-
ported by the occurrence of their remains in marine sediments free
from land relics, indicating burial far out to sea. They had a singu-
FIG. 375. — Rhamphorynchus phytturus. (Restored by Marsh.)
larly elongated rod-like tail, with a rudder-like expansion at the end
(Fig. 375).
The pterodactyls (Fig. 376) had short tails, and were usually
small and slender. Fully differentiated as first found, the ptero-
saurs underwent no radical change of structure during their career, and
the steps of their remarkable evolution are for the most part unknown.
The appearance of true birds. — A less bizarre, but really greater
evolution, was the contemporaneous differentiation of true birds, which
appeared hi a similarly advanced state of development. The ancestors
of the pterosaurs and the birds may doubtless have been closely allied
far back toward the point of common saurian or stegocephalian diver-
gence, but there is no evidence whatever that the pterosaurs developed
into true birds. The two are types of analogous and parallel evolu-
tion, and not of successive relationship. The earliest known bird,
Archceopteryx macrura (Fig. 377), shows an advanced state of evolution,
and at the same time clear traces of reptilian ancestry. From this
THE JURASSIC PERIOD.
103
ancestry it retained a long, vertebrated tail, reptile-like claws, and
fore limbs, teeth set in sockets, biconcave vertebrse, and separate pel-
vic bones. On the other hand, its head and brain were bird-like,
its anterior limbs adapted to flying in bird fashion, not in pterosaurian
fashion, its posterior limbs modified for bird-like walking, and most
distinctive of all, it was clothed with feathers. The perfect develop-
ment of the feathers, while yet the body retained so many reptilian
features, is most notable. But for their fortunate preservation, it is
uncertain whether the creature would have been classed as bird or
FIG. 376. — A pterodactyl, Pterodactylus spectabilis, from the
Eichstadt, Bavaria, about three-fourths natural size. (After H. v.
ic stone at
ieyer.)
reptile. The known species was somewhat under the size of a crow.
Two skeletons and a single isolated feather found in the lithographic
quarries of Bavaria, are the only relics yet recovered from the Upper
Jurassic beds.
The non-placental mammals. — The marvelous deployment of aquatic
and terrestrial reptiles, of pterosaurs and birds, makes the scanty
record of the mammals all the more singular. Only a few jaws of the
size of those of mice and rats have been found either in America or in
Europe (Fig. 378). These low types are referred, without complete
104
GEOLOGY.
certainty, to the marsupial order. They appear to have been insectivo-
rous. No certain evidences of placenta! mammals have been found.
The insects. — The bisects appear to have included members of
PIG. 377. — The earliest known bird. Archoeopteryx macrura. The long vertebrated
tail, the clawed digits of fore limbs, and the toothed jaws are ancestral features
to be specially noted. (H. v. Meyer.)
nearly all the fossilizable groups that were not dependent on the angio-
spermous plants, directly or indirectly. As before, the neuropterous
and orthopterous orders predominated, the former represented by
well-formed dragon-flies, in addition to may-flies and termites; the
THE JURASSIC PERIOD.
105
latter by cockroaches, crickets, etc. To these were added many
beetles of several different families, some Hemiptera, the earliest known
FIG. 378. — Lower jaws of American non-placental (polyprotodont) mammals of the
Upper Jurassic, a, Priacodon ferox; b, Dryolestes morax. One and one-half times
natural size. (After Marsh.)
Diptera, represented by flies, and the earliest known Hymenvptera,
represented by ants; but the Lepidoptera (butterflies and moths) were
yet awaiting the appearance of the flowering plants.
Little that is new relative to the life of the fresh waters is revealed
by the Jurassic strata.
CHAPTER XIV.
THE COMANCHEAN (LOWER CRETACEOUS) PERIOD.1
Introductory.
AT the close of the Jurassic period, large areas in the western part
of North America which had been submerged became land, and at
the beginning of the succeeding period, the larger part of the North
American continent was above sea-level. The history of the Cretaceous
period, as that term has commonly been used, is rather complex.
The general sequence of events in North America is somewhat as fol-
lows: (1) Early in the period there was a somewhat widespread warp-
ing of the continental surface, resulting in sedimentation at many
points within the continental borders. Submergence was extensive
in Mexico and Texas, and the sea extended thence as far north as the
Ouachita Mountains, and temporarily beyond, while on the Pacific
coast a narrow border of the present land was beneath the sea. Along
the Atlantic and Gulf coasts, and in some parts of the western interior,
considerable tracts were brought so low, or into such an attitude,
as to become the sites of deposition, though not submerged beneath
the sea. A prolonged period of sedimentation followed these geo-
graphic changes. (2) This period of sedimentation was followed by
an interval when most of the areas which had recently been the sites
of deposition, whether marine or non-marine, were exposed to subaerial
degradation. (3) After this interval had been sufficiently long to
allow of very considerable erosion of the Early Cretaceous beds, the
sea encroached upon the Atlantic and Gulf borders, covering, and in
general spreading beyond, the non-marine formations of the earlier
stage. It again covered Texas, and presently extended northward
over the Great Plains to the Arctic Ocean, forming a great
1 For a full review of the American Cretaceous, up to 1891, see White (C. A.) Bull.
82, U. S. Geol. Surv.
106
THE COMANCHEAN PERIOD. 107
mediterranean sea several hundred miles wide from the mouth of the
Mackenzie River on the north, to the mouth of the Rio Grande on the
south, dividing the continent into two unequal parts, a larger eastern,
and a smaller western. On the Pacific coast also, the sea extended
its area somewhat at the expense of the land. There have been few
greater incursions of the sea over the land, and therefore few equally
great geographic changes, during the long history of the North Ameri-
can continent. A long period of deposition was initiated by the sub-
mergence, and this was succeeded in turn by (4) a widespread with-
drawal of the waters. The mediterranean sea disappeared, and the
borders of the land were extended seaward on the east, the south and
the west, and the continent became nearly or quite as large as now.
The formations of the Cretaceous system are commonly divided
into two main series, the Lower and Upper. To the former are
referred the deposits of the earlier and lesser submergence, and to the
latter, those of the later and more extensive submergence. The
distinctness of the Lower and Upper Cretaceous is however so great
that it seems, on the whole, in keeping with the spirit of the classi-
fication here adopted, to regard the two series as separate systems,
and the corresponding divisions of time as separate periods. From
the physical standpoint, the distinction between the Upper and Lower
Cretaceous is greater than that between the different parts of any Paleo-
zoic system, as commonly classified, if the Mississippian and the Penn-
sylvanian be regarded as separate systems, and greater than that between
the Cambrian and the Ordovician, or between the Devonian and
Mississippian. The paleontological phase of the question is discussed
elsewhere. If the Lower Cretaceous be separated from the Upper,
it may be called the Comanchean or Shastan system.1 The propriety
of this classification becomes the more striking, since it is equally
applicable to other continents.
This classification involves no new idea. Hill, who has made a
special study of the North American Cretaceous where both the Lower
and Upper systems are developed, has repeatedly emphasized their
distinctness,1 and Neumayr,2 after reviewing the relevant evidence
1 The first of these terms has been applied to the Lower Cretaceous of Texas (Hill),
and the second, by Le Conte and others, to the Lower Cretaceous of California.
2 See references to his papers in the following pages.
3 Erdegeschichte Bd. II, p. 377.
108 GEOLOGY.
drawn chiefly from the phenomena of the old world, concludes that
if the distinctness of the Lower and Upper Cretaceous had been known
when the accepted time-divisions were established, they would have
been made separate divisions of equal rank with the Triassic, Jurassic,
etc. The Lower and Upper Cretaceous are therefore here considered
as two somewhat closely associated periods, coordinate with the Triassic
and Jurassic.
The following table (p. 109) gives some idea of the relations of the
two systems, and of their parts, though the correlations for different
regions are not to be regarded as exact.
THE COMANCHEAN (SHASTAN, LOWER CRETACEOUS) SYSTEM.1
The warping which marked the opening of the Comanchean period
occasioned the development of extensive lakes or other basins of
non-marine deposition in some parts of the continent, while other
parts were depressed beneath the sea. The Comanchean deposits of
the Atlantic and Eastern-Gulf coastal plains, and in certain parts of
the western interior, are non-marine; those of the western Gulf region,
extending as far north as the Ouachita Mountains and even a little
beyond, are chiefly marine, while those of the Pacific coast are wholly
so. From the distribution of the marine strata of the system, it is
clear that by far the larger part of the continent was above sea level
during the period, unless the deposits have been extensively removed
by erosion, and this does not appear to be the case.
The Atlantic and Gulf Border Regions.
To understand the relations of the Cretaceous on the Atlantic
coast,2 it should be recalled that during most of the Paleozoic era,
the area east of the Appalachians, as far as the present coast and
beyond, was land, and that when the Appalachians came into exist-
ence at the close of the Paleozoic, some parts of Appalachia were bowed
or broken so as to become the sites of deposition, and here the Triassic
1 For an excellent summary of the Lower Cretaceous, see Stanton's Lower Cre-
taceous Formations and Faunas, Jour, of Geol., Vol. V, 1897, pp. 579-610. As the
title implies, this paper deals with paleontological, rather than physical questions.
Full bibliography.
2 Data concerning the Lower Cretaceous formations of the Atlantic coast are to
be found in reports of the Geological Surveys of New Jersey and Maryland (Vol. I).
See also McGee, article cited below.
THE COMANCHEAN PERIOD.
d
109
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110
GEOLOGY.
FIG. 379. — Map showing the distribution of the Comanchean formations in North
America. The conventions are the same as in preceding maps.
THE COMANCHEAN PERIOD. Ill
beds of the Atlantic province were laid down (p. 1). The sedimen-
tation was attended and followed by igneous intrusions, and prob-
ably by faulting and warping. At the close of the Triassic period,
as nearly as now known, the surface was again deformed, and a period
of erosion which lasted through the Jurassic period inaugurated.
By the beginning of the Comanchean period, both the Appalachian
Mountains and the area of the present Piedmont plateau had been
degraded well toward base-level.1 Little warping of the surface there-
fore appears to have been needed to convert portions of the coastal
lands into sites of sedimentation. That part of the Comanchean
(Lower Cretaceous) system which is found along the Atlantic coast is
called the Potomac 2 series. The formations tentatively referred to
the Jurassic 3 are generally included in this series. Other names
have local application (see table above).
The conditions of sedimentation along the eastern part of the Gulf
coast appear to have been similar to those along the Atlantic, and
the corresponding formations constitute the Tuscaloosa 4 series.
The approximate surface distribution of the Potomac and Tusca-
loosa series is shown on the accompanying map (Fig. 379), from which
it is seen that they are not traceable into each other at the surface;
but there is general agreement that they were, at least in part, con-
temporaneous. Neither is believed to represent the whole of the
Comanchean system as developed elsewhere. On the basis of fossils,
the Tuscaloosa is thought to represent only the latter part of the time
when the Potomac was in process of deposition, while both are referred
to the early rather than the late part of the period. If both are
referable to the earlier part of the Comanchean period, it is not now
possible to say how far this is to be accounted for by the emergence
of the regions where the series occur before the later part of the period,
1 The possible Jurassic beds of the Atlantic coast (p. 59) are not brought into
consideration here.
2McGee, Am. Jour. Sci., Vol. XXXV, 1888, pp. 120-143; Clark and Bibbins,
The Stratigraphy of the Potomac Group in Maryland, Jour, of Geol., Vol. V, 1897.
pp. 479-506. This article treats of the Potomac as a whole; also Bull. Geol. Soc.
Am., Vol. XIII, pp. 187-214, 1902.
3 Marsh thought the whole Potomac series Jurassic, Am. Jour. Sci., Vol. II, 1896,
pp. 433-477.
4 Smith and Johnson, Bull. 43, U. S. Geol. Surv., 1887. For a better and later
summary of the Tuscaloosa of Ala., see Smith, Geol. Surv. Ala., 1894.
112 GEOLOGY.
and how far the result of the removal of the later beds by erosion.
The unconformity between this series and the (Upper) Cretaceous
above shows that erosion removed some of the former, before the
deposition of the latter.
Constitution and structure of the Potomac and Tuscaloosa series.—
In its mode of formation the Potomac series appears to belong to the
less familiar of the two great classes of deposits, the terrestrial, as
distinguished from the marine. As already noted, the whole eastern
mountain and plateau region seems to have suffered peneplanation
during the Jurassic period, attended inevitably by the deep decay
of the underlying crystalline and other rocks, and the consequent
accumulation of a heavy mantle of residuary earth and insoluble rock.
The warping which inaugurated the Comanchean period seems to have
involved a rise of the axis of the Appalachian tract, and a consequent
rejuvenation of the drainage from it, while the coast ward tract was
left relatively flat, or perhaps bowed into a concave attitude, making
it a zone of lodgment for the sediments brought down from the west.
The quickened drainage of the axial tract, acting on material prepared
for easy removal, loaded itself with a burden it could not carry across
the low coastal tract, and deposition resulted. It is perhaps not
necessary to assign concavity or permanent submergence to the lodg-
ment tract, if the loading of the rejuvenated head-waters of the
streams was sufficient ; but lakes, marshes, etc., were probably features
of the area. These conditions are in harmony with the constitution
of the deposits, which consist of gravel (or conglomerate), sand (or
sandstone), and clay.
The gravel (or conglomerate) at any point is made up principally
of materials derived from the formations adjacent on the west, and
subordinately from the subjacent formations. It is often arkose in
the immediate vicinity of the feldspar-bearing crystalline rocks, but
elsewhere it is composed chiefly of the resistant products of mature
weathering. Among these, quartz, from the quartz veins of the crys-
talline rocks is often conspicuous. Chert, quartzite, and sandstone from
the Appalachians, are also constituents. The gravels are sometimes
disposed irregularly, constituting lenses or beds of varying thickness.
The sands are sometimes fine and the grains well rounded, as if
long transported by moving water, and sometimes coarse and angular,
as if they had been subjected to but little wear. Like the gravel,
THE COMANCHEAN PERIOD. 113
the sand-beds are sometimes rather lawless in their disposition. Locally
the sand contains feldspar grains, or bits of kaolin which have resulted
from their decay. The presence of the feldspar (or kaolin) in the sand,
like the presence of pieces of schist in the gravel, shows that erosion
sometimes exceeded rock decay. This betokens high land to the west
whence the sediments were derived, and is one of the reasons for the
belief that the region west of the site of deposition was tilted upward
at this time.
Much of the feldspar of the crystalline rocks was already decom-
posed at the time of the Potomac sedimentation, and the resulting
clay was often separated, in deposition, from the coarser grains of
quartz. This separation was the work of the waters which trans-
ported the detritus, and while it was effected by physical means, and
for physical reasons, it resulted in the separation of materials which
were chemically unlike. The separation was by no means always
complete; but it went sufficiently far to give rise to beds of clay of
such purity and magnitude that they have been extensively utilized
(especially in New Jersey l) for the manufacture of clay wares. The
beds of clay, like those of gravel and sand, are sometimes in the form
of huge lenses. The clay often shows little trace of stratification,
and is notable for its bright and variegated colors, black, white, yel-
low, purple, and red being not uncommon. White is to be looked upoc
as the normal color; the others are the result of various impurities,
the blackness being due to organic matter.
The irregular disposition of the clay, sand, and gravel is doubt-
less the result of the physical conditions where the sedimentation
took place. On an exposed coast, the waves and littoral currents
tend to spread the coarse sediment along the shore, while the finer
sediments are carried farther out. Where the Potomac sediments
were deposited, such processes appear not to have been effective, and
the sediments vary notably from point to point. Their disposition
is often such as to suggest that they were deposited along the lower
courses of rivers or at their debouchures, where shore-waters had
little effect upon them. On the other hand, the perfect separation
of the sand from the clay in many places, points to the existence of
1 Cook, Geol. Surv. of New Jersey, Report on Clays (1870), and Kiimmel, Ries, and
Knapp, 1904.
114 GEOLOGY.
local conditions which allowed of the differentiation of sediments
to an unusual degree. This differentiation may have been effected in
large part by land drainage. If marshes, lagoons, and small isolated
bodies of water were the sites of deposition, and if the contributing
streams were of varying velocities, and therefore bearing loads of vari-
ous grades of coarseness, some of the peculiarities of structure would
find their explanation. Slight oscillations of level, or slight shif tings
of the debouchures of the streams may have caused the deposits of
separate streams to become continuous. Similar results might have
been brought about if the conditions were estuarine. If this was the
case, there must have been a barrier to the east, shutting out the sea,
and of such a barrier there is some evidence.1
In addition to the clastic sediment, there is a little lignite, and
some iron ore, and though both are widely distributed, neither is of
much commercial value. Both formations are natural results of the
conditions assigned. Amber has been found in the series at several
points, though in small quantities only.2
The Tuscaloosa series is like the Potomac in general constitution,
though gravel is, on the whole, less important. Clay predominates
in the lower portion, and sand in the upper. The bright colors and
the irregular stratigraphy characteristic of the Potomac are also char-
acteristic of the Tuscaloosa series.
The Potomac, as already implied, is a series of formations, rather
than a single formation. Even if the lowermost part of the series
heretofore called by this name proves to be Jurassic, the portion above
is not a unit. In Maryland 3 two distinct formations (the Patapsco
and the Raritan) have been recognized within it, the one unconform-
able on the other. A similar subdivision has not been established for
the series farther south.
Stratigraphic relations. — Along the Atlantic Coast the Potomac
series rests unconformably on the Triassic (New Jersey) and pre-Cam-
brian (Pennsylvania and south) formations. Its general strati-
graphic relations are shown in Fig. 380. The Tuscaloosa series rests
on crystalline schists (pre-Cambrian) at the east, but farther west on
1 Clark and Bibbins, Bull. Geol. Soc. of Am., Vol. XIII, pp. 209-12.
2 Rollick, Am. Nat., Vol. XXXIX, 1905.
3 Clark, Jour, of Geol., Vol. V, 1897, pp. 479-506; also Maryland Geol. Surv.,
Vol. I. pp. 191-2.
THE COMANCHEAN PERIOD. 115
Paleozoic strata. Both the Potomac and Tuscaloosa are overlain
unconformably by the Upper Cretaceous beds.
Thickness. — The Potomac series rarely reaches a thickness of 700
feet, while the thickness of the Tuscaloosa series in Georgia, Alabama,
and Mississippi reaches 1000 to 1500 feet.
FIG. 380. — Section showing relations of various members of the Coastal series. C,
Comanchean; K, Cretaceous; E, Eocene; M, Miocene; PI, Pliocene; Q, Quaternary.
The Texas Region.1
The Lower Cretaceous system is much more fully represented in
Texas than farther east and north, but its stratigraphic relations
are the same. The beds appear at the surface over an area distant
from the coast (Fig. 380), dip seaward at a low angle, and are concealed
near the coast by younger formations.
The Comanchean system of Texas embraces three distinct series.
The oldest was perhaps contemporaneous with the Potomac series,
but the youngest is probably younger than any part of the series of
the Atlantic Coast. The system is much thicker in Texas than far-
ther east, ranging from 1000 to about 4000 feet, the slighter thickness
being to the northeast, and the greater to the southwest. In Mexico,
these thicknesses are greatly exceeded.
The three series of the Comanchean system, commencing below,
are (1) the Trinity, (2) the Fredericksburg, and (3) the Washita.
1 Present knowledge of the Cretaceous in this region is due largely to the work
of R. T. Hill. The latest account published is in the 21st Ann. Kept. U. S. Geol.
Surv., Pt. VII. An earlier paper, Geology of Parts of Texas, Indian Territory and Ar-
kansas adjacent to the Red River, Bull. Geol. Soc. Am., Vol. V, 1893, pp. 297-338, con-
tains a list of the author's other papers, the more important of which, from the pres-
ent point of view, are the following: The Texas Section of the American Cretaceous,
Am. Jour, of Sci., Vol. 34, 1887; The Topography of the Cross Timbers and Surround-
ing Regions of Northern Texas, Idem, Vol. 33, 1887; Description of the Cretaceous Rocks
of Texas and their Economic Value, First Ann. Kept. Geol. Surv. of Texas, 1888; Meso-
zoic Geology of Southwestern Arkansas, Ann. Rept. Geol. Surv. of Arkansas, 1888;
The Comanche Series of the Arkansas-Texas Region, Bull. Geol. Soc. Am., Vol. II, 1890;
Note on the Texas-New Mexican Region, Idem., Vol. Ill, 1891.
Further accounts of the Cretaceous of Texas are to be found in the Second Ann.
Rept. Geol. Surv. of Texas (Taff), and in the 18th Ann. Rept. U. S. Geol. Surv., Pt.
II, pp. 217-237, Hill and Vaughan.
116 GEOLOGY.
The Trinity series,1 the oldest member of the system in Texas,
is unconformable on the Triassic or older rocks. Its fossils are such
as to have raised the question of its reference to the Jurassic system,
but it is not commonly so classified. The basal part of the formation
is like the Potomac of the east, in being non-marine, but the upper
parts were deposited in sea- water. The series consists of sands, clays,
marls, and limestones. In the lower part of the series any one of
these various sorts of rock grades into any other, vertically or
FIG. 381. — Section showing position of the Comanchean beds near Austin, Texas. The
amount of faulting is exceptional. Length of section about 4 miles. (U. S. Geol.
Surv.)
horizontally.2 The series contains both asphalt and bitumen.3 It
extends northward to the Ouachita Mountains in Arkansas and Indian
Territory, where the waters of the epoch appear to have had their
shore. After the deposition of more than 2000 feet (maximum) of
sediment, there appears to have been a shoaling of the waters, followed
by a deepening which inaugurated the next epoch.
The Fredericksburg series, which overlies the Trinity, is more
widespread than its predecessor, though it does not now cover all of
the former, because of subsequent erosion. The series extends north
to the Ouachita uplift, and perhaps around its western end over
a limited area farther north, and west to New Mexico. The earliest
beds of the series are clastic, and of shallow- water origin; but thick
beds of limestone (or chalk) occur in other parts of the series. In the
vicinity of the shores, especially next to the Ouachita uplift, where
the shore phases of the formation are best known, the formation is
relatively thin and mainly clastic. The Fredericksburg series is
much less variable, both in thickness and composition, than the Trinity
series below, and contains more calcareous material.
The Fredericksburg formation is overlain by the Washita, a series
which records an epoch of shoaling waters, though the sea was some-
1 Hill, op. cit., p. 129 et seq.
2 Idem.
3 Eldridge, Bull. 213 U. S. Geol. Surv., p. 301.
THE COMANCHEAN PERIOD.
117
times clear enough to allow of the accumulation of impure limestone. The
series is made up of alternating beds of clay, limestone, sandstone, etc.
In its typical development in Texas, more than half the Comanchean
system is calcareous, and chalk, rather than limestone in its ordinary
form, prevails. In general, the clastic beds thicken toward the Ouachita
FIG. 382. — Shows the effects of faulting on outcrops of the various Cretaceous for-
mations, near Uvalde, Texas. Ce (Edwards limestone), Cdr (Del Rio clay),
and Cb (Buda limestone) are the local subdivisions of the Comanche system.
Kef (Eagle Ford formation) is the lower part of the (Upper) Cretaceous.
Mountains, while the beds of chalk, which point to clearer water, thicken
in the opposite direction. Locally the Comanchean system of Texas
is deformed and notably faulted (Figs. 381 and 382).
Westward and northward extension. — The Comanchean forma-
tions originally spread westward from Texas over a considerable
area in eastern New Mexico, and probably even to Arizona, where the
system is 5000 feet thick l and carries the Texan fauna,2 and north-
1 Ransome, Professional Paper 21, and Bisbee folio U. S. Geol. Surv.
2 Stanton, Professional Paper 21, U. S. Geol. Surv., p. 70.
118 GEOLOGY.
ward around the western end of the Ouachita Mountains, an undeter-
mined distance into Kansas.1 Though they appear at the surface in
small areas only, their extent may be considerable beneath younger
formations. The exact relations of the Comanchean strata of Kansas
(Cheyenne sandstone, Kiowa shale, etc.) to those of Texas have not
been established. The Kansas beds appear to be referable mainly
to the Washita epoch, though some of them may be older. The aggre-
gate thickness of the Kansas beds is less than 200 feet. The Coman
chean system also occurs in Oklahoma (near Garrett) and Colorado
(near Canyon City).2
In Mexico. — As in Texas, the Comanchean system of Mexico is
mainly limestone, and, though but imperfectly known, it has been
estimated to have the extraordinary thickness of 10,000 to 20,000 feet.
While the system in Mexico agrees with that of Texas in its large pro-
portion of calcareous rock, the soft chalk of the plains grades into
hard limestone in the mountains. This difference is perhaps the result
of the dynamic movements to which the Mexican strata have been
subject.
The distribution and character of the Comanchean system in Mexico
are such as to show that a large part of that country was beneath the
sea. It has been conjectured that the waters of the Atlantic and
Pacific mingled over the site of some part of the present land, but this
has not been proven. If there was union, it was probably across
southern Mexico or perhaps even Central America, and so related,
by shallow water restriction or by ocean currents, to the Californian
coast, as to prevent free faunal intermigration.
In its abundance of limestone, the series of Texas and Mexico
resemble the Lower Cretaceous of the northern part of South America,
and southern Europe. It is a notable fact also, that the faunal affini-
ties of the Comanchean system are with South America and Europe,
rather than with California, where marine Lower Cretaceous strata
are known.
1 For summary of the Lower Cretaceous of Kansas, see Prosser, " Comanchean
Series of Kansas," the Univ. Geol. Surv. of Kans., Vol. II, 1897. This volume give.v
bibliography of the Lower Cretaceous of the state. See also Hill, Am. Jour. Sci., Vol
I, 1895, and Bull. Geol. Soc. Am., Ill, p. 85; Gould, Am. Geol., Vol. XXV, pp
10-40; and Cragin, Am. Geol., Vol. VI, pp. 233-8.
2Stanton, Jour. Geol., Vol. XIII, p. 657.
THE COMANCHEAN PERIOD. 119
The Northern Interior.
Though the sea is not known to have had access to the western
interior of North America, north of Kansas, during the Comanchean
period, clastic beds of fluvial or lacustrine origin, which should per-
haps be referred to this period, are known at various points farther
north. The beds in question (sometimes classed as fresh-water Jurassic
under the names Morrison,1 Como,2 Atlantosaurus beds, etc.), occur
in parts of Wyoming, South Dakota (Fig. 349), Colorado, and New
Mexico,3 though their distribution has not been accurately deter-
mined.4 They probably reach northward to Montana, but they are
best known along the Front range through Colorado and Wyoming,5
and in the Black Hills.6 They extend south beneath the marine
Comanchean of southwestern Colorado, Oklahoma, and New Mexico.7
Beds suspected of being of the same age are known in south-
western Wyoming and western Colorado. If these beds be the
equivalent of the Morrison, the formation is distributed, perhaps with
notable interruptions, over an area 600 miles long by 300 miles
wide (Fig. 379). The limited exposures are due to the fact that most
of the beds are covered by younger formations, being seen only where
there has been deformation and erosion. The rather remarkable uni-
formity of thickness of the formation, as thus far reported (commonly
between 200 feet and 300 feet), indicates that it was deposited on a
1 Cross, Pikes Peak Folio, U. S. Geol. Surv., 1894.
2 Scott, An Introduction to Geology, 1897.
3 Lee, Jour, of Geol. Vol. X, pp. 36-50.
4 The following references touch the question of the classification of these beds:
Marsh, O. C., Proc. Amer. Assoc. Adv. Sci., 1878, Vol. XXVI, pp. 210, 220; Amer.
Jour. Sci., ser. 4, 1896, Vol. II, pp. 433-47; Amer. Jour. Sci., ser. 4, Vol. VI, 1898,
pp. 105-15; Osborn, H. F., Jour. Acad. Nat. Sci. Phil., 1888, Vol. IX, p. 187, and
Scott, W. B., Introduction to Geology, 1897, p. 477; Knight, W. C., Bull. Geol. Soc.
Amer., 1900, Vol. XI, pp. 383-87, and Wyo. Exp. Sta. Bull. 45, p. 138; Ward, Les-
ter F., 20th Ann. Kept. U. S. G. S., 1900, Pt. II, p. 377; Williston, S. W., Amer. Jour.
Sci., ser. 4, 1901, Vol. XI, p. 114, and Jour, of Geol., Vol. XIII, 1905, p. 338; Hatcher,
J. B., 1903, Memoirs Carnegie Mus., Vol. II, No. I, pp. 67-72; Barton, N. H., Bull.
Geol. Soc. Amer., 1904, Vol. XV, pp. 388, 425, and Edgemont and New Castle folios,
U. S. Geol. Surv.
5 Knight classes the Como beds with the Jurassic. Bull. 45, Wyo. Exp. Station,
p. 134.
6 Ward, Jour. Geol., Vol. II, p 250.
7 Stanton, Jour. Geol., Vol. XIII. The latest studies, reported in this paper, leave
the age of this formation in doubt.
120 GEOLOGY.
rather flat surface by agencies capable of distributing sediments with
some degree of equality. These beds are frequently unconformable
on older formations, including the marine Jurassic. In the Black Hills
region, the Morrison beds are overlain by other non-marine beds of
Early Cretaceous or Comanchean age,1 some of which are coal-bearing.
Farther north, in Montana, Alberta, and Assiniboia, there is a
series of beds (the Kootenay and Cascade formations, etc.)2 similar
in character to those just described, but not known to be connected
with them. In the area where first described, the Kootenay formation
occupies a narrow belt about 140 miles long and 40 miles wide. Simi-
lar beds have been discovered farther north. The Kootenay beds
are mainly clastic, and are very inconstant in character, both vertically
and horizontally. They contain some coal, and the fossils are mostly
of plants of Early Cretaceous types.3 The Kootenay formation is said
to attain a maximum thickness of 7000 feet.
The non-marine Kootenay of these northerly localities rests uncon-
formably on marine Lower Cretaceous beds, the fossils 4 of which
are so like those of the Early Cretaceous of the Queen Charlotte
Islands, as to lead to the belief that the beds in the two regions were
contemporaneous and laterally continuous, and therefore that the
sea of the northern interior entered from the west. The connection may
have been in some such position as that of the late Jurassic (Fig. 348).
To the Morrison and Kootenay formations a lacustrine origin has
usually been assigned. There is perhaps no adequate ground for
questioning this conclusion for some parts of the formations, but the
character of some of the beds and the nature and distribution of their
fossils suggest a fluviatile origin for parts, and perhaps for large parts,
of the series. The variations in the character of the beds within short
distances is most easily explained as the work of meandering rivers.
1 Darton and Smith, Edgemont, S. D.-Wyo. folio, and Darton, New Castle, Wyo.-
S.D. folio, U. S. Geol. Surv.
2 See Cascade formation, Fort Benton, Mont, folio, U. S. Geol. Surv.
3 G. M. Dawson, Am. Jour. Sci., Vol. 38, pp. 120-127. A brief general description
of the formation. A fuller statement by the same author is found in Report Geol.
Surv. of Canada, 1885. For the corresponding formations in the United States, see:
Newberry, Am. Jour. Sci., Vol. XLI, pp. 191-201; Weed, Bull Geol. Soc. Am. Vol.
Ill, 1892, pp. 301-23; Weed and Pirsson, 18th Ann. Kept. U. S. Geol. Surv.
and Bull. 139, U. S. Geol. Surv.; and Wood, Am. Jour. Sci., Vol. 44, 1892, p. 401.
4 Whiteaves, Contributions to Canadian Paleontology, Vol. I, Pt. II.
THE COMANCHEAN PERIOD. 121
It is not easy to see why fossils of plants and land animals should
be so widely distributed, both vertically and horizontally, in a lacus-
trine formation, though their wide dissemination in a region of land
deposits would be readily understood if the region were flat and sub-
ject to aggradation. The leg-bones of large land animals (dinosaurs)
are frequently found upright, or inclined at some considerable angle
to the bedding planes, as if the animals had been mired. Some
of the bones of the Morrison beds are said to be in such condition as
to show that they were exposed and partly decayed previous to their
burial. In other cases, one end of a bone appears to have undergone
subaerial decay, while the other was preserved. If one end was sunk
in mud while the other was exposed, as might be in marsh or fluviatile
deposits, this phenomenon would be explained. In the Black Hills
region there are some beds of limestone composed largely of the secre-
tions of fresh- water algae.1
The position of these formations in reference to the Rocky
Mountain axis is much the same as that of the Potomac to the
Appalachian axis, and the same conception as to the mode of origin
may be entertained. This involves some lacustrine 2 or quasi-lacus-
trine deposition, combined with fluvial and sheet wash aggradation.
The extraordinary thickness assigned to some parts of the Kootenay
formation (7000 feet) is scarcely credible under any hypothesis, except
as interpreted on the principles of oblique deposition and subsequent
thickening by shear and mashing.
It is not now possible to correlate the Kootenay formation with
the Morrison, nor is it possible to correlate either the Kootenay or
the Morrison with the Potomac, the Tuscaloosa, or the Comanchean
of Texas ; but, except perhaps the Kootenay, the other series are thought
to correspond approximately with the Trinity of the Texas region,
and with the lower part of the Potomac. The difficulty in the correla-
tion of these formations with those of the coastal regions lies in the
facts (1) that they nowhere approach each other, and so have no
stratigraphic inter-relations, and (2) that there is no reliable standard
with which they may be separately compared.
Between Kansas and the Black Hills of South Dakota, Lower Cre-
'Darton and Smith, Edgemont, S. D.-Neb. folio, U. S. Geol. Surv.
2Dawson, loc. cit.
122 GEOLOGY.
taceous strata are not known. They may underlie some parts of the
later formations between these localities, or they may be wholly absent.
The Pacific Border.
In the United States. — The Lower Cretaceous beds have great
development in California, where they attain their maximum known
thickness. They here constitute the Shastan group,1 made up of two
principal divisions, the Knoxville below, and the Horsetown above.
The former has a maximum thickness of about 20,000 feet (according
to estimate), and the latter of 6000 feet. These thicknesses are local
and exceptional, but thicknesses of 12,000 to 15,000 feet have been
calculated in several places. The Sacramento valley was the site
of the thickest deposits, the sediments being furnished by the newly
uplifted Sierra and Coast ranges. Throughout most of the great
series, including the basal beds, there are evidences of shallow-water
origin.2 Dark clay slates predominate, but there is also a nota-
ble amount of sandstone. The fossils of the Knoxville beds, like those
of the Jurassic of the same region, point to faunal connections with
Russia, while those of the Horsetown beds seem rather to point to
connections with southern Asia and Europe. These changes in life
imply geographic changes of importance.
The Shastan group is found along the western side of the Sacra-
mento valley, and in the Coast ranges of California, Oregon,3 and Wash-
ington. Where its base has been observed, it sometimes rests on
metamorphic rocks of unknown age, and sometimes on the Jurassic.
It is overlain unconf ormably 4 in some places, and without apparent
unconformity in others, by the Upper Cretaceous (Chico 5), while in
1 Gabb and Whitney, Paleontology of Cal., II; White, On the Mesozoic and
Cenozoic Paleontology of California, Bull. 15, U. S. Geol. Surv.; Becker, Bull.
19, U. S. Geol. Surv.; Turner, Geology of Mount Diablo, Cal., Bull. Geol. Soc. Am.,
Vol. II; Diller, Cretaceous Rocks of Northern California, Am. Jour. Sci., Vol. XL,
1890, and Cretaceous and Early Tertiary of Northern California and Oregon, Bull.
Geol. Soc. Am., Vol. IV, 1892; Diller and Stanton, idem, Vol. V, The Shasta-Chico
Series, a Summary for the Pacific Coast brought up to 1894.
2 Diller and Stanton, Bull. Geol. Soc. Am., Vol. V.
3Merriam, Jour, of Geol., Vol. IX, 1901, p. 71.
4 Becker, Bull. 19, U. S. Geol. Surv., p. 12; also Monograph XIII, U. S. Geol. Surv ,
p. 188.
8 Fairbanks, Jour, of Geol., Vol. Ill, pp. 415-430, and San Luis, Cal., folio, U. S.
Geol. Surv.
THE COMANCHEAN PERIOD. 123
still others, the latter system is absent.1 The Knoxville formation of
the Coast Range of California contains some igneous rock.2
The faunas of the Shastan and Comanchean systems are markedly
unlike, and since the differences do not seem referable to climate, it
seems necessary to suppose that there was some sort of a barrier
between the two regions. In the United States, this barrier seems
to have been a wide one, but in Mexico it was probably narrow,
for the Comanchean fauna, or some part of it, extends west to the
western part of Mexico (Sonora), while farther south the Pacific fauna
reached eastern Mexico (San Luis Potosi). The exact position of
the barrier which separated the oceans is not known. It appears
to have lain farther west in northern Mexico, and farther east in
southern. The failure of the two faunas to mingle does not prove
the complete separation of the oceans, but it indicates that any con-
nection there may have been was slight, or that the barrier between
them extended well to the south, perhaps as far as Central America.
Though the exact time relations of the Comanchean and Shastan
series have not been determined, they are believed to be approximately
equivalent. It follows that the exact relations of the Shastan system
to the Tuscaloosa and Potomac series are not defined.
North of the United States. — Farther north, the Lower Cretaceous
beds (Queen Charlotte series) occur in the Queen Charlotte Islands,3
where they have a thickness of between 9000 and 10,000 feet. In
British Columbia, the coast line was east of the Coast Ranges, and
extended farther and farther east with increasing latitude, until the
ocean swept clean across the site of the Cordilleras in the early part
of the period, and extended south along the area which is now
the east base of the mountains.4 In this southerly extension of the
sea, the area of deposition was separated from the Pacific by land
occupying the site of the Selkirks. The Kootenay formation is per-
haps partly contemporaneous with these marine beds, but largely
younger. The Comanchean system of British Columbia generally rests
1 Roseburg, Ore., folio, U. S. Geol. Surv.
2 Fairbanks, San Luis folio, U. S. Geol. Surv.
3 Dawson, Geo. M., on the Earlier Cretaceous Rocks of the Northwestern Por-
tion of the Dominion of Canada, Am. Jour. Sci., Vol. 38, 1889, pp. 120-127. This
article contains a map showing relations of land and water on the northern Pacific
coast in the early Cretaceous.
4 Dawson, Science, March 15, 1901; and Bull. Geol. Soc. Am., Vol. XII, p. 87.
124 GEOLOGY.
unconformably on the Triassic system, and contains some volcanic
material and, locally, some coal.
Farther north, the Lower Cretaceous has not always been separated
from the Upper, but the former has extensive development in some
parts of northern Alaska,1 where it locally contains coal, and is known
even north of the Arctic circle. It is also believed to occur on the west
coast of Greenland, opposite Disco island. From the fossils, the Green-
land beds are believed to represent some such horizon as that of the
Kootenay, or Potomac.2
Panama. — Conglomerate of Early Cretaceous age is said to occur
on the isthmus of Panama,3 its materials having been derived from
the south. The Cretaceous beds here rest unconformably on forma-
tions of late Jurassic (probably) age.
THE CLOSE OF THE COMANCHEAN (LOWER CRETACEOUS) PERIOD.
In the latter part of the Comanchean period, or at its close, there
were considerable changes in the geography of the continent. Along
the Atlantic and Gulf borders were changes (perhaps before the close
of the period) which converted considerable tracts of the known Potomac
and Tuscaloosa series from areas of deposition to areas of erosion.
In Texas, the sea was withdrawn, and the Comanchean system was some-
what deformed and faulted, while in Mexico the deformation of the
system was notable. Following these changes, the Comanchean sys-
tem was subjected to prolonged erosion. Geographic changes also
affected the western coast. Locally, as in the southern Coast range
of California, there was folding of the Lower Cretaceous beds,4 and
volcanic activity, while in other places the sea spread itself over areas
which had been land. Still other areas appear to have emerged at
this time, and never to have been again submerged.5
On the whole, therefore, the deformative movements at the close of
the Early Cretaceous period were considerable. They were more
1 Schrader, Bull. Geol. Soc. Am., Vol. XIII, pp. 245-6, Professional Paper, 20,
pp. 72-77; Mendenhall and Schrader, Professional Paper, 15, p. 37; and Collier,
Bull. 218, U. S. Geol. Surv., pp. 15-17.
2 White and Schuchert , Cretaceous Series of the West Coast of Greenland, Bull.
Geol. Soc. Am., Vol. IX, pp. 343-368, 1898.
3Hershey, Bull. Dept. Geol. Univ. of California, Vol. 2, pp. 240-249.
4 Fairbanks, Jour. Geol., Vol. Ill, pp. 415-430, and San Luis folio, U. S. Geol. Surv.
5 Ransome, Bisbee, Ariz, folio, U. S. Geol. Surv.
THE COMANCHEAN PERIOD. 125
extensive than those which occurred in the midst of any one of the
Paleozoic periods as now defined, if the Mississippian and Pennsylvanian
be regarded as separate periods. To appreciate the force of this point
in its bearing on the distinctness of the Early and Later Cretaceous
periods, it is needful to anticipate the history of the latter sufficiently
to say that it was inaugurated by a notable submergence, affecting
great areas. It brought the Atlantic and Gulf coastal plains beneath
the sea, allowing (Upper) Cretaceous beds of marine origin to be deposited
on the eroded surfaces of the Potomac, the Tuscaloosa, and the Coman-
chean series. In Texas, no species of marine life is known to have
lived over the time-interval recorded by the unconformity between
the two systems. Not only was the Texan area of the Comanchean series
submerged, but the waters extended themselves far beyond their
earlier limits, covering hundreds of thousands of square miles which
had long been land. On the Pacific coast of the United States, the
seas of the Late Cretaceous period extended farther east than during
the Comanchean period in some places, for the Upper Cretaceous strata
sometimes rest on pre-Cretaceous beds.1 In British Columbia, the
reverse was the case, while in some parts of Alaska, the Upper Creta-
ceous is unconformable on the Lower.2 On stratigraphic grounds,
therefore, the distinctness of the Lower Cretaceous from the Upper
in North America is such as to warrant their recognition as separate
systems, and their distinctness in some other continents is perhaps
equally great. It is for these reasons that the Lower Cretaceous
is here regarded as a system distinct from the Upper.
Thicknesses of strata afford no basis for the separation of systems,
yet it may be noted that though the average thickness of the Coman-
chean system is not so great as the average thickness of the formations
of most Paleozoic periods, yet its maximum known thickness (26,000
feet in California, measured by the customary method) is greater than
that which any Paleozoic system is known to possess at any point in
America.
THE LOWER CRETACEOUS IN OTHER CONTINENTS.
Toward the close of the Jurassic period, it will be recalled, con-
siderable areas of central Europe which had been submerged were
1 Fairbanks, Am. Jour. Sci., XLV, 1893, p. 478.
2Schrader, Bull. Geol. Soc. Am., Vol. 13, Plate 40.
126 GEOLOGY.
converted into dry land, while other areas emerged from the sea, but
were not so situated as to be drained. In the deposits of some of
the lakes, marshes, estuaries, and other lodgment basins which resulted
from these geographic changes, the transition from the Jurassic period
to the Early Cretaceous 1 is recorded. The oldest deposits in these
non-marine waters in England (Purbeck beds) are classed as Jurassic,
while later but conformable beds (Wealden) are generally regarded
as Cretaceous. The interruption of marine sedimentation in southern
Europe at the close of the Jurassic was less general, and over con-
siderable areas the Lower Cretaceous succeeds the Jurassic conform-
ably, both being marine. In Russia, the gradation from Jurassic
to Lower Cretaceous is often so complete that no plane of division
can be drawn between them.
The European areas of deposition may be grouped in two principal
provinces, a northern and a southern. To the former belong the Cre-
taceous beds of England, central Europe, and Russia; to the latter,
those of southern France, Spain, Italy, and the Balkan peninsula.
The two provinces were separated by a series of islands which now
form the highlands of France, southern Germany, and Austria. The
northern province seems also to have been partly shut off from the
Atlantic to the west. The southern province was continued east over
the corresponding latitudes of Asia, and south over the northern border
of Africa.
In Europe, as in North America, the Cretaceous, as that term has
been used, is divisible into two major parts, a Lower and an Upper,
as distinct as successive systems usually are. In general, the Lower
is much more restricted in its distribution than the Upper, and is,
to a larger extent, of non-marine origin. In both these respects,
the Lower Cretaceous of Europe is in harmony with the Comanchean
of North America.
During the initial stages of the Early Cretaceous period, the areas
of sedimentation were more or less isolated; but later, advances of
the sea enlarged some of these separated areas, and finally united
many of them by bringing them beneath a common sea. The expan-
sion of the epicontinental sea was still greater at the opening of the
1 Early Cretaceous is here used instead of Comanchean for the time during which
the strata corresponding to the Comanchean of the North American continent were
laid down.
THE COMANCHEAN PERIOD.
127
Later Cretaceous period. Stated in other terms, the widespread sub-
mergence of areas which were land during the Early Cretaceous period,
marked the commencement of a new period, because it established
new geographic relations of great importance. It should be stated,
however, that the separation of the two systems in Europe, where
the Upper Cretaceous is often conformable on the Lower, is some-
FIG. 383. — Sketch-map of Europe during the Neocomian stage of the Early Cretaceous
period. The shaded areas are areas of deposition, (After De Lapparent.)
what less pronounced than in North America. The Upper Cretaceous
is, however, much more widespread than the Lower.
The Cretaceous systems of England, France, and other parts of
western Europe are best known, and the classification now some-
what generally accepted, though often with slight modifications, is
based on the formations of that part of the continent, and is shown
in the table on p. 109.
In other continents, the Lower and Upper Cretaceous have not
always been clearly differentiated, yet enough is known to show that
128 GEOLOGY.
the Lower and Upper Cretaceous systems are, in general, markedly
different, both in origin and distribution.
In Europe. — The general relations of the Lower Cretaceous of
western Europe have already been suggested. The lowest beds of the
system in different regions are probably not strictly contemporaneous,
for the basins in which they were deposited appear to have come into
existence at somewhat different times, some of them enduring from
the Jurassic period. The non-marine deposits of the early Neocomian
were later succeeded, in many places, by beds of marine origin, and of
greater extent.
The slow encroachment of the sea over western Europe during the
Early Cretaceous period seems not to have been without interruptions,
for reverse changes, more or less local and temporary, took place now
and again, re-establishing lacustrine conditions, or severing marine
communications between regions which had been overspread by a
common sea.
In general there is great diversity in the formations of the Lower
Cretaceous in central and western Europe. They embrace all sorts
of clastic rocks, from coarse to extremely fine (plastic clays); also
glauconitic beds, limestone, and beds of coal (northwestern Germany)
and iron ore. They embrace, indeed, about all varieties of sedimentary
rock except chalk, the rock from which the name " Cretaceous " was
derived.
The iron ore which occurs locally in the Lower Cretaceous of Ger-
many, differs from most formations of this ore. It occurs in beds
made up of nodules of iron carbonate derived from the Jurassic beds.
These ore beds are, therefore, of clastic origin. They reach a maxi-
mum thickness of nearly 100 feet. In general the Lower Cretaceous
beds of Europe are more generally indurated than those of eastern
North America.
In England, the Wealden formation is thought to have been accu-
mulated as a great delta, 20,000 or 30,000 square miles in extent,
in an inland body of water which occupied a part of England, and parts
of the continent to the east. The sediments are thought to have come
from the north. The later Neocomian beds of England contain some
greensand (glauconite). The succeeding Gault series, mainly clastic
and nearly 1000 feet (maximum) thick, is more widespread than the
Neocomian.
THE COMANCHEAN PERIOD. 129
In southern Europe the marine sedimentation of the preceding
period was not interrupted, and the Lower Cretaceous beds rest con-
formably, and with poor definition, on the Jurassic. Limestone is
here the most common sort of rock. In southeastern Europe, Lower
Cretaceous beds are found in the southeastern part of Russia (Cauca-
sus, Transcaucasia and Transcaspian regions) and about Moscow.
Other continents. — Lower Cretaceous formations of marine origin
are widespread in Siberia, Japan,1 and southern Asia, but in limited
areas only in most other parts of tne continent. The system is believed
to have slight development in the mountain regions of northwestern
Africa, where it is really a continuation of the Lower Cretaceous of
southern Europe, and is unconformable beneath the Upper Cretaceous,
and in South Africa.2 Marine Lower Cretaceous is also widespread
in the northern part of South America, but not elsewhere east of the
Andes. The absence of marine Lower Cretaceous beds east of the
Andes in the southern part of South America is in keeping with its gen-
eral absence about the borders of the South Atlantic generally. On
the other hand, marine Lower Cretaceous beds occur in many places
about the southern Pacific and Indian Oceans,3 as in India, the Hima-
layan region, Australia, New Zealand, and at a few points on the east
coast of Africa, and perhaps elsewhere. The areas where the system is
exposed are, however, mostly small.
Climate. — In the aggregate, the known fossils of the Lower Cre-
taceous of America are not such as to indicate great diversity of climate.
Even in Greenland, the climate seems to have not only been milder
than now, but as warm as that of warm temperate regions of to-day.
While the climate of the Cretaceous periods has not been deter-
mined in detail, European fossils seem to afford better evidence of the
existence of zones than those of America. From them paleontologists
have thought to find warrant for the hypothesis that the climate under-
went more or less fluctuation during the course of the periods.
The fresh-water fossils of those deposits of central Europe which
represent the transition from the Jurassic to the Lower Cretaceous, are,
1 Outlines of Geology of Japan, 1902, pp. 59-73.
2 Ann. Kept. Geol. Com. Cape of Good Hope, 1901, p. 38: and Corstorphine, His-
tory of Stratigraphical Investigations in South Africa, Kept. S. Af. Assn. for Adv.
of Sci., 1904. Geology of Cape Colony, Rogers, 1905, pp. 281-330.
3 Neumayr. Erdegeschichte, Bd. II.
130 GEOLOGY.
on the whole, of such a character, particularly as to size, as to indi-
cate a climate which was far from tropical. So far as they afford a
warrant for inference, the climate of central Europe would seem to
have been comparable with that of the temperate portions of America
to-day. The fossils of lower latitudes denote a warmer climate.
Close of the period. — Geographic changes of importance occurred
in various parts of the earth at the close of the Early Cretaceous period,
and are recorded (1) in the unconformities between the Lower and Upper
Cretaceous systems, and (2) in the differences in their distribution.
Unconformity between the two systems is recorded at some points
in Europe, in North Africa, in Australia, where it is great, and in South
America. The differences in distribution between the two systems
will appear in the account of the following system.
THE LIFE OF THE COMANCHEAN PERIOD.
The terrestrial vegetation. — Fossil plants constitute the chief record
of the life of the opening epoch of the Comanchean. The very earliest
Comanchean flora was akin to that of the Jurassic, in that the cyca-
deans, conifers, ferns, and horsetails were the dominant forms. In
Europe, where the Jurassic grades into the Cretaceous through the Pur-
beck and Wealden (and their continental equivalents), this rather
monotonous group continued to hold possession of the land throughout
the Lower Cretaceous, except in Portugal, where angiosperms appeared.
The members of this group continued their slow modernization, but did
not undergo any radical change in Europe during this period. So far
as known, the same was true of Asia, Africa, and Australia, but data
relative to these regions are scanty. The same appears also to have
been true of northwestern America, where (in Shastan and Kootenay
series) these groups made up the recorded flora and formed beds of
coal.
The introduction of angiosperms. — But in the central and eastern
American region representatives of the present reigning dynasty of plants,
the angiosperms, including both monocotyledons 1 and dicotyledons,
appeared in the Lower Potomac, and developed strongly during the
period, so that by the opening of the (Upper) Cretaceous they seem
1 Monocotyledons have been reported earlier, but the identification is not beyond
question.
THE COMANCHEAN PERIOD. 131
to have overrun all the continent. This is one of the most radical
evolutions in the known history of the plant kingdom. While the
precise time and place of origin of the angiosperms remains a question.
FIG. 384. — A cycadian trunk from the Black Hills, Dakota, Cycadeoidea dakotensis
Ward, Lower Cretaceous. (After Ward.)
yet to be solved, present data seem to hedge it about more closely
than most such questions. The evidence, as it now stands, points
to the borders of the North Atlantic as the place of origin, and the
late Jurassic or earliest Comanchean as perhaps the time, though the
132 GEOLOGY.
evidence is less strong on this point. The new flora is best represented
in the Potomac formation of the Atlantic coast, notably in Virginia
and Maryland, where it has been carefully studied by Ward and Fon-
taine.1 It is represented in the Tuscaloosa formations of Alabama2
at a somewhat later stage (Upper Potomac), in Kansas in a highet
(Washita) horizon,3 and in the Black Hills.4 The angiosperms do not
occur in the lowest plant-bearing horizon of Texas, the Trinity, nor
in the lowermost horizons in Kansas. The exact horizon of the angio-
sperms of the Black Hills, relative to that of the earliest angiosperms
of the Atlantic coast, is not determined, but the angiosperms form a
much smaller part of the flora, and its general aspect is less advanced.
In west Greenland, about Lat. 70° N., the Kome series contains a few
angiosperms, while in the next higher series, the Atane, probably
Upper Cretaceous, the angiosperms outnumber the lower forms.5 While
exact correlation is impossible, it seems probable that the angiosperm-
ous evolution was there somewhat more tardy than on the Atlantic
coast of the United States. In Portugal, primitive types of angio-
sperms appear in the Aptian stage (p. 109), but not among the 88 species
of the Neocomian stage. At the top of the Lower Cretaceous, or base
of the Upper (Albian stage), angiosperms are much more abundant,
and belong to familiar genera (Sassafras, Laurus, Eucalyptus, Myrica).
Interstratified with the several plant beds are fossiliferous marine beds
which resemble those of the Comanchean series, but they do not afford
the means of exact correlation, though they indicate that the Fredericks-
burg series approximately corresponds to the middle or upper por-
tion of the Lower Cretaceous of Portugal, and favor the view that
the Atlantic coast took precedence, both in time and numbers, in the
evolution of the angiosperms. The limitation of the angiosperms
to the mere border of the eastern continent is also more consistent
1 Ward, Am. Jour. Sci., Vol. XXXVI, 1888, pp. 119-131; 15th Ann. Kept. U. S.
Geol. Surv., 1896, Pt. I, pp. 463-542; Science, Vol. V, 1897, pp. 411-419.
Fontaine, Am. Jour. Sci., Vol. XVII, 1879, pp. 151-157, 229-239; Mon. XV,
U. S. Geol. Surv., 1889 ; Proc. U. S. Nat. Mus., Vol. XV, 1892, pp. 487-495; Bull.
145, U. S. Geol. Surv., 1896.
2 Smith, Kept. Geol., Coastal Plain, Ala., 1894, pp. 307-308.
3Knowlton, Am. Jour. Sci., Vol. L, 1895, pp. 212-214.
4 Ward, Jour. Geol., Vol. II, 1894, pp. 250-266; 19th Ann. Kept. U. S. Geol. Surv.,
1897-98, pp. 521-712.
5Heer, Flora Fossilis Arctica. White and Schuchert, Bull. Geol. Soc. Am., Vol.
IX, 1898.
THE COMANCHEAN PERIOD. 133
with their introduction there by sea currents from the western con-
tinent, than with an origin on the eastern continent, for they were
not there generally prevalent until the beginning of the Upper Cre-
taceous.
The view that seems best justified at the present stage of
evidence is that the angiosperms developed on the old lands of the
eastern part of North America, and that until the close of the Lower
Cretaceous they had only spread westward as far as Kansas and the
Black Hills, northward as far as Greenland, and eastward to the coast
of Portugal, but not to Europe generally, nor to the western part of
North America, for they do not appear in the Kootenay or the Shastan
series. As the northeastern part of North America had long been land,
and has left no record of plant-life, there is nothing to indicate how
much earlier angiosperms may have begun their evolution there.
The Jurassic beds of the western part of the continent and of Europe
give negative evidence as to a dispersion earlier than the Cretaceous
period.
In the most typical region on the Atlantic coast nearly half the
known 800 species of Comanchean age are angiosperms. They began
in marked minority in the lowest Potomac and increased to an over-
whelming majority in the uppermost beds.1 The earliest forms are
ancestral, but not really primitive, and throw little light on the deriva-
tion of the angiosperms. While some are undifferentiated, the majority
bear definite resemblances to modern genera, and some (as Sassafras,
Ficus, Myrica, and Aralia), are referred to living genera, while others
are given generic names implying the similarity of the fossil leaves
to those of living plants (as Saliciphyllum, willow-like leaves, Querco-
phyllum, oak-like leaves, and analogous names for plants whose leaves
resembled those of the elm, walnut, maple, eucalyptus, and others).
To these were added, in the Amboy (N. J.) clays at the very close of
the period, figs, magnolias, tulip trees, laurels, cinnamon, and other
forms referred to modern genera, but not to modern species. The
cycadeans had dropped to an insignificant place, and the conifers and
ferns, while not equally reduced, were markedly subordinate to the
angiosperms.
The land animals. — The aspect of the vertebrate life was inter-
mediate between that of the Jurassic and of the Upper Cretaceous, and
1 Newberry, Mon. XXVI, U. S. Geol. Surv., 1895, p. 23.
134
GEOLOGY.
has been sketched already. Very little is known of other forms of
terrestrial life.
The fresh-water fauna. — The molluscan fauna of the inland waters
had assumed a pronouncedly modern aspect as illustrated in Fig. 385.
It had probably assumed consider-
able importance through the exten-
sion of the fresh waters, but the
record is by no means so ample as
would be expected if the deposits
were made mainly in lakes and river
b e ^^—12 channels, and this is an additional
FIG. 385.-Fresh-water fauna of the Co- reason for the growing opinion
manchean (Lower Cretaceous) from that the terrestrial deposits were
Montana (after Stanton). PELECYPODA: . .111
a, Unio farri Stanton; b, Unio douglassi in considerable part the products
ortmanni Stanton; e, Campeloma har- sient type, due to Overflows,
loWtonensis Stanton. , , ,
storm-wash, sheet-wash, and other
forms of more strictly subaerial aggradation.
The marine faunas.— There were two very distinct series of marine
faunas, implying two distinct maritime provinces — that of the Mexi-
can Gulf and that of the Pacific. The former had its connections east-
ward with Portugal and the Mediterranean region, the latter, north-
ward and westward with Asia and Russia. No species common to
the two provinces is known. The two faunas were not only distinct,
but were even contrasted in their generic aspects.1 In the Gulf region,
Echinoidea (Fig. 386, a-c), Terebratulacea, Ostreidce, Rudistce, Chamadce,
Cyprina, Protocardia, Cyprimeria, Naticidce, Glauconia, Turritella (Fig.
386, /), Nerinea, Hamites, Pachydiscus, Schlcenbachia, Engonoceras, and
Turrilites are common, and some of them extremely abundant. But
half of the above genera and families are absent from the Pacific
province, the rest are rare or of local occurrence only, and always
represented by different species. On the other hand, in the Pacific
province, Aucella (Fig. 387, k, I, ra), which is wholly absent from
the Gulf region, is extremely abundant in the Knoxville beds,
and Belemnites, Rhynchonella (Fig. 387, r), Crioceras, Anchyloceras.
Hoplites (Fig. 387, c), Phylloceras (Fig. 387, 6), and Lytoceras (Fig.
387, a), are common, while rare or absent from the Gulf province.
Stanton, Jour. Geol., Vol. V, 1897, p. 607.
THE COMANCHEAN PERIOD.
135
Trigonia (Fig. 386, /) is common in both, but the species are not
related. It will be noticed that the pelecypods (Fig. 386, d-h),
gastropods (Fig. 386, i-l), and echinoids dominate in the Mexico-
Texan region, the oyster family being foremost, while the cepha-
lopods (Fig. 387, a-c), and Aucella (Fig. 387, k, I, m), a pelecy-
pod, dominate the Pacific fauna, though the list of gastropods
(Fig. 387, d-h) and pelecypods (Fig. 387, i-q) is considerable there
also. Corals and crinoids are rare in both provinces.
FIG. 386. — The Comanchean fauna of the Texan province. ECHINOIDS: a, Holaster
simplex Shum.; 6, Diplopodia texanum Roemer; c, Hemiaster dalli Clark. PELE-
CYPODA: d, Anatina austinensis Vaughan; e, Homomya austinensis Vaughan;
/, Trigonia emoryi Conrad; g, Lima vJacoensis Roemer; h, Pecten texanus Roemer.
GASTROPODA: i, Fusus texanus Vaughan; /, Turritella budaensis Vaughan ; k,Ceri-
thium (?) texanum Vaughan; I, Trochus Sp. CORAL: m, Parasmilia texana Vaughan.
(After Vaughan.)
The question of the cause of this distinctness has already been
alluded to, but cannot be positively answered. The complete dis-
tinctness and the contrast of aspect are obviously most completely
explained by a land barrier separating the two provinces, much as at
present, and there is now no proof that this was not the case. If, how-
ever, the oceans joined, the best appeal perhaps is to ocean currents
of different temperatures. Assuming from general meteorological
principles the existence of trade-winds, they would doubtless drive
an equatorial Atlantic current westward through the opened tract
and onward across the Pacific, while a northerly current might not
improbably descend the Pacific coast, as one now does as far as British
136
GEOLOGY.
Columbia, attended by a fauna quite different from that of the warmer
coast farther south, not so affected. This is not an appeal to great
climatic differentiation, which is not sustained by the flora, but to
FIG. 387. — Fauna of the Shastan series, chiefly Knoxville. CEPHALOPODA: a, Lyto-
ceras batesii Trask; b, Phylloceras knoxvillensis Stanton; c, Hoplites angulatus
Stanton. GASTROPODA: d, Astresius liratus Gabb; e, Amberleya dilleri Stanton;
/, Cerithium paskentaensis Stanton; g, Hypsipleura gregaria Stanton; h, Turbo
moyonensis Stanton. PELECYPODA: i, Pecten complexicosta Gabb; /, Corbula (?)
persulcata Stanton; k and I, Aucella piochii var. orata Gabb ; m,A crassicottis Key-
serling; n, Astarte calif ornica Stanton; o, Area tehamaensis Stanton; p, Nucula
storrsi Stanton; q, Leda glabra Stanton. BRACHIOPODA: r, Rhynchonellawhitneyi
Gabb. (After Stanton.)
such a moderate difference as has probably always existed between
the high and low latitudes. The flora of the high latitudes is not
tropical but warm temperate.
CHAPTER XV.
THE (LATER) CRETACEOUS PERIOD.
THE Later Cretaceous period (which will hereafter be called the
Cretaceous) may be said to have been ushered in, so far as North
America is concerned, by a notable encroachment of the sea on the
land.
Within the land area of the North American continent, the Creta-
ceous occurs (1) along the Atlantic Coastal plain; (2) along the
corresponding plain of the Gulf, both east and west of the Mississippi;
(3) over the region of the Great plains, probably stretching north contin-
uously from the Gulf of Mexico to the Arctic ocean; (4) at many
points in the Cordilleran mountains, and (5) over considerable areas
along the Pacific coast. In all these regions, the system is chiefly marine,
though not without extensive fresh-water or terrestrial deposits. It
thus appears that while the geographic distribution of the Cretaceous
system has much in common with that of the Comanchean, the
younger system is much more widespread (Fig. 388).
The Atlantic border region.1 — The Cretaceous beds of the Atlantic
coast come to the surface in a belt near the western margin of the
Coastal Plain, immediately east of the outcrop of the Lower Creta-
ceous system. The principal exposures are in New Jersey, Delaware,
Maryland, and Virginia. The lowest beds are not believed to repre-
sent the earliest beds of the system as developed elsewhere. The
Cretaceous beds have been but little disturbed, and still dip, as when
deposited, slightly to seaward. In that direction the beds pass
beneath later formations.
The Cretaceous formations of the Coastal Plain are made up of
conformable (probably) beds of clay, sand, limestone, and greensand
1 Besides the State Reports referred to under the Comanchean, see Clark, Bull.
Geol. Soc. of Am., Vol. 8, 1897, pp. 315-358, and Weller, Jour, of Geol., Vol. XIII,
p. 71.
137
138
GEOLOGY.
FIG. 388. — Map showing the distribution of the Cretaceous formation in North America.
The conventions are the same as in preceding maps.
THE CRETACEOUS PERIOD. 139
marl, the last being rather characteristic of the system. The beds
of sand and clay are mainly unindurated, and do not differ notably
from other sedimentary beds of similar materials. Of limestone,
there is but little on the Atlantic coast, but more about the Gulf.
A chief constituent of the greensand marl is glauconite, primarily
a hydrous silicate of potash and iron,1 occurring in grains. Glauconite
is now making in some parts of the sea, and from the positions in which
it occurs, the following are inferred to be the conditions necessary for
its origin:2 (1) water of moderate depth, 100 to 200 fathoms being
the most favorable; (2) a meagre supply of land-derived sediment,
and (3) the presence of foraminifera. The production of the glau-
conite seems to be effected by chemical changes induced in the sedi-
ments as the result of the decomposition of the organic matter con-
tained in the foraminiferal shells. The greensand marl of the Cre-
taceous system is somewhat widely distributed along the Atlantic
coast, showing that the conditions for its origin were widespread.
Since it is sometimes in distinct beds, separated from one another by
formations of other composition, there must have been a recurrence
of the conditions necessary for its origin; but even in those parts of
the system where clay and sand predominate, glauconite is not gen-
erally altogether absent. Similar marls are found in the Cretaceous
of Europe and in New Zealand, though in Europe they occur in the
Lower system as well as the Upper. The abundance of greensand
marl — not a common formation outside the Cretaceous — in the corre-
sponding systems of different continents, adds another to the many
striking inter-continental resemblances.
The Cretaceous formations of the Atlantic coast have certain pecu-
liarities of structure, especially in that some of the beds when traced
along the strike, wedge out in one direction or the other. The suc-
cession of thin beds of unlike constitution shows that the conditions
of sedimentation were subject to numerous changes in the course of the
period. These changes may have been the result of changing depths
of water, changing heights of adjacent land, or of changing currents
1 Glauconite is usually impure, and, as it occurs in nature, contains several other
ingredients.
2 For brief summaries concerning the origin of greensand marl, see Clark, Jour,
of Geol., Vol. II, p. 161, and Reports of the State Geologist of New Jersey, 1892. For
fuller accounts, see Challenger Report on Deep Sea Deposits.
140 GEOLOGY.
in the water. The frequent variations in the character of a stratum when
traced laterally show that different conditions prevailed at different
points along the coast at the same time.
Thickness. — The aggregate thickness of the Upper Cretaceous beds
nowhere exceeds a few hundred feet. In New Jersey it is about 500
feet, and in Maryland 200.
Classification. — Various classifications have been in use for the Cre-
taceous formations of the Atlantic coast, that now generally adopted
being as follows : 1
4. Manasquan formation.
3. Rancocas formation.
2. Monmouth formation.
1. Matawan formation.
These formations are not severally continuous throughout the Coastal
region. Thus the Matawan formation does not appear at the sur-
face south of Maryland, being overlapped in that direction by later
beds. All the formations show notable variations when traced along
their strikes, and borings to the east show that they also vary when
traced to seaward from their landward margins.
Changes in the beds since deposition. — Though the beds have
been but little changed since their deposition, the slight alterations
are worthy of note. Locally, the porous beds of marl have been changed
from green to brown by the decomposition of the silicate and the forma-
tion of ferric oxide. Cementation, chiefly by ferric oxide, has indurated
certain beds at some localities, and many of the conspicuous hills
within the area of Cretaceous outcrops owe their existence to a capping
of this ironstone. The cemented layers are most likely to occur at the
junction of formations of different texture, a generalization which holds
in other unindurated, or but partially indurated systems. The lime-
stone of the formation is often thoroughly indurated.
The Gulf border region east of the Mississippi. — Along the Gulf coast,
as along the Atlantic, the Cretaceous beds appear at the surface some
distance from the coast, and dip seaward at a low angle. The belt
of their exposure extends from Georgia on the east, through Alabama
1 Clark, Bull. Geol. Soc. of Am., Vol. VIII, p. 326. See Repts. of the State Geol-
ogist of N. J. for older classification. The subdivision of this system, as proposd by
Clark, has been somewhat modified by Knapp and Weller, Jour, of Geol., Vol. XIII,
pp. 71-84.
THE CRETACEOUS PERIOD.
141
and Mississippi to western Tennessee and Kentucky on the west and
north. If any of the formations once had greater extension to the
northward, as is probable, they have been removed by erosion.
The system is best known in Alabama l where three principal divi-
sions are recognized; the Eutaw below (mainly clays and sands, some
FIG. 389. — Map showing the positions of the several members of the Cretaceous sys-
tem in Alabama and adjacent states. C, Tuscaloosa series; Ke, Eutaw formation;
Ks, Selma chalk; Kr, Ripley formation; Tr, Tertiary. (After Smith.)
greensand, 300 feet), the Selma Chalk (Rotten limestone, 1000 feet)
in the middle, and the Ripley (mainly sand, 200-500 feet) above. The
Eutaw is believed to be the equivalent of the Matawan formation
of the Atlantic coast, and the Ripley is thought to be older than the
Rancocas. Either the area where the Cretaceous formations of the
Gulf region are exposed emerged from the sea before the end of the
period, or the youngest beds have been removed by erosion from the
area where the system is exposed.
1 For an account of the Cretaceous of Alabama, see Smith, Report of the Alabama
Survey for 1894. See also Safford, Geology of Tennessee, 1869, and Hilgard, Geol-
ogy of Mississippi, 1860.
142 GEOLOGY.
The Cretaceous formations of Alabama illustrate some of the
peculiarities of structure displayed by the corresponding beds of New
Jersey. The Selma Chalk, which is thick in the western part of the
state, thins to the eastward, and disappears altogether before the
eastern border of the state is reached. Two formations in the eastern
part of the state, therefore, seem to be the equivalent of the three
in the western part. The interpretation of these relations has been
suggested elsewhere. The relations of the several formations to each
other and to the Tuscaloosa, are shown in Fig. 389.
The Cretaceous beds of the Gulf coast (Alabama) have been dis-
turbed to a greater extent than the corresponding beds along those
parts of the Atlantic coast where the system has been carefully studied.
They have been deformed into low anticlines and synclines in some
places, and even faulted (Fig. 390) to a slight extent.
FIG. 390. — Section of the Ripley formation on the right bank of the Tombigbee river,
Alabama, above Moscow, showing deformation and faulting. The total thick-
ness of the beds shown in the figure is not more than 75 feet. The faults are there-
fore slight. (Smith.)
The Western Gulf border region.1 — The general stratigraphic rela-
tions of the system in this region are the same as farther east, but
deposition seems to have been well under way before the oldest beds
of the corresponding system farther east began to be laid down. The
system here is much thicker than that farther east, and is made up
of a series of alternating beds of sand, shale, limestone, and marl, most
of which are of marine origin, attaining a maximum thickness of 4000
feet. Three principal series are recognized 2 : The Dakota (or Wood-
bine) formation; (2) the Colorado series, including the Eagle Ford,
the Austin, and the Taylor formations, and (3) the Montana series,
or Navarro formation.
The Dakota series, 600 feet and less thick, is largely of ferruginous,
argillaceous sand, with some lignite, and is probably of non-marine
origin. The Eagle Ford formation, about 500 feet thick, is essentially
1 Hill and Vaughan, 18th Ann. Kept. U. S. Geol. Surv., Pt. II, pp. 238-242.
2 Hill, 21st Ann. Rept., U. S. Geol. Surv., Pt. VII, p. 114. These names sup-
plant older ones. Woodbine is the equivalent of the old Lower Cross Timber, and the
Taylor and Navarro formations were formerly described under the name Ponderosa.
THE CRETACEOUS PERIOD. 143
of bituminous clay, with a little limestone. Its fossils are chiefly
marine. The Austin formation, 600 feet or less thick, is limestone or
chalk, of marine origin. The Taylor formation, 600 feet or so thick,
consists of calcareous clay marls. The Navarro formation is similar
to the last in constitution, but contains some glauconite. Its thick-
ness is about 1000 feet. The Navarro formation is probably the
equivalent of much of the Upper Cretaceous farther east. The suc-
cession of beds is in reality much more complex than the preceding
statement would indicate, for some of the formations enumerated are
made up of many beds of different composition. The oil of the Cor-
sicana field of Texas is derived from the Montana series 1 (Webberville
formation). Locally, the system is much faulted as shown in Fig. 382.
The Cretaceous system of Texas is continued north into Arkansas2
where each of the above series is present. Together they have an esti-
mated thickness of 1500 feet, though the original thickness was much
greater. The system also extends west into New Mexico,3 where it
sometimes rests on the Red beds, and sometimes on Carboniferous
limestone. Locally, as in the Cerillos hills, the system contains coal.
The Cretaceous of the western Gulf region differs from the corre-
sponding system farther east, in its greater thickness, and in its greater
proportion of calcareous matter, chiefly in the condition of chalk. Of
limestone or chalk, the Cretaceous of the Atlantic coast contains little,
that of the eastern Gulf region (Alabama and Mississippi) more, and
that of Texas much. Nor is the chalk confined to Texas. The equiva-
lent of the Austin formation (the Niobrara chalk) extends far to the
north, and is the greatest chalk formation of the continent. Much
of the chalk resembles the gray chalk of Europe, and some of it the
white. Most of the American chalk, like the European, is made up
in considerable part of forammiferal shells. Fragments of coral
and of molluscan shells, the spicules of sponges, and coccoliths, also
abound.
Unlike the Comanchean system, the Cretaceous has not its great-
est development in Mexico. While present in that country, it is less
widespread and less thick than the preceding system.
1 Hill and Vaughan, Austin, Tex., folio, U. S. Geol. Surv., p. 7.
2 Hill, Ark. Geol. Surv., Ann. Kept., 1888, Vol. II.
3 Johnson, School of Mines Quarterly, Vol. XXIV, p. 332, and Keyes, Am. Jour.
Sci., Vol. XVIII, 4th series, p. 360.
144 GEOLOGY.
THE WESTERN INTERIOR.
Before the Cretaceous period was far advanced, non-marine sedi-
mentation was in progress over an extensive area in the western interior.
Later, the sea entered this region from the Gulf, covering a wide belt
east of the Rocky mountains, and reaching perhaps to the Arctic ocean,
thus connecting the subtropical seas with the polar.
The Cretaceous system of the western interior consists of the fol-
lowing subdivisions:
4. Laramie.
3. Montana.
Fox Hills.
Fort Pierre.
2. Colorado.
Niobrara.
Benton.
1. Dakota.
The Dakota formation. — The Dakota formation is mainly of non-
marine origin, being comparable in this respect to the oldest formations
of the Comanchean system, the Potomac, the Tuscaloosa, the lower part
of the Trinity, the Morrison, and the Kootenay. (See note, p. 190.)
The Dakota formation is present over the Great plains generally,
though buried over the greater part of the area. It extends west-
ward beyond the eastern ranges of the western mountains, though in
the mountain region, the ar"ea of deposition was greatly interrupted
by elevations which rose above the lakes, marshes, or river flats where
the sedimentation took place. In northern Montana, it is not known
west of the Rocky Mountains.1 The original eastern boundary of the
formation is not known, for erosion has removed it from considerable
areas which it once occupied. Remnants of the formation are now
exposed as far east as eastern Iowa2 and Minnesota. It must origi-
nally have covered an area 1000 miles wide and 2000 miles long within
North America. Its outcrops are chiefly along the eastern and west-
ern borders of the plains, and in the mountains to the west. Here
it sometimes overlaps Paleozoic and earlier Mesozoic formations, and
rests on the Archean (Fig. 391).
1 Willis, Bull. Geol. Soc. of Am., Vol. 13, p. 326.
2 Calvin, Iowa Geol. Surv., Vol. I, 1892; Bain, Idem, Vol. Ill, p. 108 and Vol. V,
p. 267 — a good review of the Dakota of Iowa.
THE CRETACEOUS PERIOD. 145
North of the United States, it appears to be represented by con-
glomerate overlying the Kootenay series,1 and beds correlated with
it occur in the Frazer River valley farther west. 2000 feet of volcanic
material, referred to this epoch, occurs in Crow's Nest pass.2
In the Plains region, the Dakota formation is largely sandstone
(or quartzite) though it contains much conglomerate and clay, and
some lignite. In general, it is coarser to the west and finer to the east,
implying more vigorous drainage from the western side.
Along the east base of the Rocky mountains, where the beds have
been tilted, the less resistant beds associated with the Dakota sand-
FIG'. 391. — Section showing the Cretaceous resting on the Archean.
Walsenburg, Colo., folio, U. S. Geol. Surv.
stone have been removed, leaving its outcropping edges as ridges or
" hog backs " (Fig. 392). These ridges are characteristic of the western
margin of the Great plains, much of the way from New Mexico to
Canada. Locally, the sandstone has a pronounced concretionary struc-
ture (Figs. 393 and 394).
The Dakota sandstone is often an important source of water in
the semi-arid plains. It gets its water where it outcrops near the
mountains, and the water flows eastward down the dip of the beds.
In Dakota and elsewhere many of the deep wells go down to it for
water for irrigation and other purposes.
West of the mountains of Colorado, the area of which was above
water, the formation is less commonly sandstone. Clay or shale is
here more abundant, and beds of coal of workable thickness give some
clue to the physical conditions which prevailed, at least locally.
The Dakota formation has commonly been regarded as a lacustrine
formation, deposited during an epoch of crustal oscillation during which
the depth of the basin increased. The necessity for postulating numer-
ous oscillations and nice adjustments is largely removed, if the forma-
tion be regarded as the joint product of subaerial and flu via tile depo-
1 Dawson, Bull. Geol. Soc. Am., Vol. XII, p. 77.
2 Ibid., p. 78.
146
GEOLOGY.
sition, for deposits of this class furnish their own adjustments. The
presence of bird tracks in the Dakota of Kansas 1 and the preserva-
tion of some 500 species of plant fossils, mostly the leaves of angio-
sperms, at various points and in conditions which forbid much trans-
portation, imply the prevalence of subaerial conditions to a notable
extent at least.
FIG. 392.— A Dakota " hog back." The rock at the left is the Red beds; the ridge
near the center is occasioned by the outcrop of the resistant Dakota sandstone.
Near Boulder, Colo. (Lees.)
The thickness of the formation is, on the whole, rather uniform,
averaging perhaps 200 or 300 feet, though greater thicknesses are known.2
To the south (Texas), the Dakota formation rests on the Comanchean
system unconformably. Farther north it is often in apparent con-
formity with the Comanchean, though it often, as in the Wasatch
and Uinta Mountains, rests on older formations.
lWffliston, Univ. of Kans. Geol. Surv., Vol. IV, p. 50.
2Darton, 19th Ann. Kept. U. S. Geol. Surv., Pt. IV, and Knight, Bull. 45, Wyo.
Experiment Station.
THE CRETACEOUS PERIOD.
147
FIG. 393. — A concretion in the Dakota sandstone. Near Minneapolis, Kan.
(Schaffner.)
FIG. 394. — A group of concretions weathered out from the Dakota sandstone.
Near Minneapolis, Kan. (Schaffner.)
148 GEOLOGY.
The Colorado series.1 — The succeeding series records an exten-
sive invasion of the North American continent by the sea. The sub-
mergence went so far as to establish a connection between the Gulf
of Mexico on the south and the Arctic ocean on the north, over the
site of the Great plains, thus dividing North America into two parts
by a great mediterranean sea. It was probably not before this epoch,
and perhaps not until the next, that the exposed Upper Cretaceous
series of the Coastal plain began to be deposited, though exact cor-
relation of these widely separated series has not yet been made.
The limits of the mediterranean sea of the Colorado epoch can
only be approximately located. The western limit appears to have
extended from northern Mexico, through Arizona, Utah, eastern Idaho,
and western Montana into British Columbia, though at the west there
were probably many islands, the cores of the present mountain ranges.
The Black Hills, however, were probably submerged.2 The eastern
limit of the sea, so far as now known, lay in Minnesota, Iowa, and Kan-
sas, east of the limit of the Dakota sandstone. In Minnesota and
northern Iowa, outliers of the Colorado formation are found nearly
to the Mississippi. To the south, the sea was constricted by the Oua-
chita uplift. The area of this uplift probably extended as a penin-
sula from Arkansas into Indian Territory and Oklahoma, and the sea
passed around its western end. There may have been a connection
between the Gulf and the mediterranean sea east of the Ouachita
uplift, making the latter an island.
It is possible that the mediterranean sea of the Colorado epoch
extended much farther east in the basin of the Upper Mississippi than
is indicated above, for in a few places in Minnesota, Wisconsin, Iowa,
Illinois, Missouri, and Indiana there are beds of gravel which represent
the remnants of a once widespread formation, most of which has been
destroyed. These remnants may be Cretaceous; but, on the other
hand, they may equally well be much younger,3 so far as now known.
They are probably not marine.
Two principal divisions of the Colorado series are recognized,
the Benton (chiefly . shale) below, and the Niobrara (largely chalk
1 For subdivisions of this series, see Logan, Jour. Geol., Vol. VII, pp. 83-91.
2 Newton, Geology of the Black Hills.
3 Salisbury, Jour, of Geol., Vol. Ill, pp. 655-667. See also Proc. Am. Assoc. for
Adv. Sci., 1892.
THE CRETACEOUS PERIOD. 149
and limestone) above. Both formations are of shallow-water origin,
as shown by the structure of the beds at some points, by the bird
tracks and remains of land animals at others, and by the species of
shallow-water mollusks which abound throughout both formations.
While clastic formations predominate in the Colorado series as a whole,
there are also beds of chalk comparable to those of Europe, which
gave the name Cretaceous to the corresponding system of the old world,
Chalk occurs in Kansas,1 Iowa,2 Nebraska and South Dakota. The
chalk is not only widespread, but its amount is very great, for it locally
(mouth of the Niobrara) attains a thickness of 200 feet.
Beds of coal are of occasional occurrence in the Colorado series.
They were probably formed about the borders of the sea, or about the
islands which stood above it. Charred wood and even charcoal in
the series point to the existence of forest fires during the epoch.
The aggregate thickness of the Colorado series is locally as much
as 3000 feet, as strata are measured, though its average thickness
on the plains is much less. It is between 400 and 500 feet in eastern
Nebraska, and thickens westward.3 It has a thickness of about 2000
feet on the west slope of the Black Hills.4 Its distribution is shown
in a general way on the map (Fig. 388).
At the close of the Colorado epoch there was some deformation
of the beds of this and earlier series, as indicated by their relation to
the beds of the following epoch.5 These movements changed the
relation of land and water somewhat, and the fossils of the succeed-
ing series indicate that the sea was then deeper, at least locally.
The Origin of Chalk.
There has been much difference of opinion concerning the origin
of chalk. Its resemblance to the foraminiferal ooze of the deep seas
long since led to the belief that it was a deep-sea deposit; but closer
examination has thrown doubt on this conclusion, for it appears that
the points of difference between the chalk and foraminiferal ooze
1 Williston, Univ. of Kans. Geol. Surv., Vol. II, and Logan, Jour, of Geol., Vol. VII,
p. 85.
2 Calvin, Iowa Geol. Surv., Vol. Ill, pp. 213-235. A brief review of chalk in
North America; good bibliography.
8 19th Ann. Kept. U. S. Geol. Surv.
4 Darton, New Castle, Wyo.-S. D. folio, U. S. Geol. Surv.
6 Emmons, the Denver Basin, Monograph XXVII, U. S. Geol. Surv.
150 GEOLOGY.
are as striking as the points of likeness. Both consist chiefly of the
shells of minute protozoans, largely f oraminif era ; but with them are
associated shells of other types, some of which are similar in the two
formations, and some dissimilar. The echinoderms, the sponge spicules,
and the shells of certain microscopic plants found in the chalk seem
to correspond in a general way with those of the oozes now depositing,
and are consistent with the deep-water origin of the chalk. The mol-
luscan shells of the chalk, on the other hand, seem to point with clear-
ness to water no more than 30 to 50 fathoms deep. The distribution
of the chalk and its relations to other sedimentary beds, seem to point
to its deposition in water of moderate depth, rather than in water
comparable in depth to that in which oozes are now formed.1 That
chalk may originate in shallow water seems to be clearly indicated by
various facts which have been observed in connection with coral reefs,
past and present.2
Another point of difference between chalk and foraminiferal ooze
is found in their relative proportions of CaC03, the proportion being
much higher in chalk than in ooze. The elevation and exposure of
the chalk can hardly have led to this difference, for the extraction
of the relatively soluble lime carbonate must have increased the per-
centage of the relatively insoluble impurities. On the other hand,
the analyses of chalk which have been used in this comparison may
have been from the purer portions of the formation, and since chalk
grades off into chalky clay and chalky sandstone, varieties of chalk
containing no more lime carbonate than the oozes, are doubtless to
be found in abundance.
One of the peculiarities of the chalk beds is the presence in them
of abundant nodules of flint and chert which are not present in the
modern deposits resembling the chalk. These nodules seem to have
resulted from the subsequent concentration into concretions of the
siliceous material (sponge spicules, etc.), deposited along with the
calcareous shells which make up the body of the chalk. On the whole,
the balance of evidence seems to favor the hypothesis that the known
chalk deposits were made in relatively shallow water. The conditions
for the origin of the chalk seem to have been clear seas, with a genial
1 Wallace, Island Life, pp. 89-96. The argument for the shallow water origin
of chalk is here forcibly presented.
2 Dana, U. S. Exploring Expedition.
THE CRETACEOUS PERIOD. 151
climate. Foraminifcral shells may accumulate as well on the bottom
of a shallow sea as on the bottom of a deep one. The purity of chalk
depends not on the depth of the water, but on the absence of clastic
sediments.
The Montana series. — Following the Colorado epoch, there were
changes in the sedimentation and in the life of the western interior sea.
The sediments of the Montana series are chiefly clastic, and the area
of sedimentation was somewhat contracted. The beds are, for
FIG. 395. — Fossil-bearing concretion in the Fox Hills sandstone, Carbon Co., Wyo.
The concretions are of lime-iron-carbonate and contain many molluscan fossils.
the most part, marine, but the water shallowed as the epoch progressed,
for the Ft. Pierre beds contain fossils referable to deeper water
than those of the Fox Hills beds. Local beds of coal give evidence
of local marshy conditions. Like other parts of the Cretaceous sys-
tem of the west, the Montana series abounds in concretions, some of
which attain great size (Fig. 395).
The thickness of the Montana series is variable, and its maximum
is great. From 8700 feet (7700 being Pierre) in Colorado, it is reduced
to 200 feet in some parts of the Black Hills, though it is much thicker
in others.1
1 Darton, New Castle, Wyo.-S. D. folio, U. S. Geol. Surv.
152 GEOLOGY.
In the northern part of the United States (Montana) and in the
territory beyond ( Alberta) , a large area of deposition appears to have
come into existence at about the beginning of the Montana epoch.
The deposits made in it constitute the Belly River formation, which
is believed to be, at least in part, contemporaneous with the lower por-
tion (Ft. Pierre) of the Montana series. Here also belong the Judith
River beds.1 Like other parts of the Cretaceous system, this formation
contains some coal. The Pierre formation also yields oil at Boulder,
Colo.
The Laramie.2 — In the Laramie epoch, the submerged area of the
western interior was still further contracted, and partially shut off
from the ocean, and over a large area, in the Great plains and west
of them, an area perhaps 2000 miles long and 500 miles wide, depo-
sition was taking place in water which was sometimes salt, some-
times brackish, and sometimes fresh. Some of the deposits, too, were
made in marshes and on low lands, rather than in water. In general,
the area of deposition seems to have been near the critical level, and
for a long time maintained a halting attitude, now above the sea and
now below it. When below, it was so slightly below as not to bring
about strictly marine conditions, and when above, it was so slightly
above as to be in large measure undrained, or poorly drained. The
Laramie series may be said to record the transition from the marine
conditions of the Montana epoch, to the fresh water and land condi-
tions of the Tertiary in the region concerned, just as the Coal Measures
of the eastern interior represent the transition from the marine con-
ditions of earlier times, to the terrestrial and lacustrine conditions of
the Permian.
The general area of deposition is shown in Fig. 388. To the east
the Laramie is concealed by younger beds, preventing the accurate
determination of its border. To the north it reaches to the Lesser
Slave lake, and perhaps beyond.3 To the west, its border is often
concealed by overlapping lava-flows.4 To the south, its limit is uncer-
1 Hatcher and Stanton, Science, Vol. XVIII, p. 212.
2 For a full discussion of the Laramie, see White (C. A.) Bull. 82, U. S. Survey.
A brief statement by the same author is found in the Proc. A. A. A. S., 1889, Vol. 38.
3 McConnell, Geol. Surv. of Can. Am. Report, Vol. V, Pt. I. See also Dawson,
Can. Geol. Surv. Kept, of Progress, 82-84, and Tyrrell, Ann. Rep. II for the Lara-
mie north of the United States.
4 Button, High Plateaus of Utah.
THE CRETACEOUS PERIOD. 153
tain, because of imperfect exploration, and the presence of later beds
which conceal or obscure it, and because of erosion which has removed
it from considerable areas which it once covered. Of the Laramie
in the Mackenzie valley little is known. Within the general area
of the Laramie deposition, especially to the west, there were numer-
ous islands, some large and some small, which furnished a part of the
sediments. Neither the size nor the shape of these islands has been
accurately determined.
Lithologically, the Laramie series consists primarily of sandstone
and subordinately of shale; but with these clastic formations there
is much coal. Both shale and coal are more abundant below than
above, while in the upper part of the series conglomerate is not rare.
In general, too, beds of non-marine origin increase in importance in the
upper part of the series. The materials of the Laramie formation
seem to have been derived principally from the pre-Paleozoic rocks
of the mountains. This, as well as the fact that the Laramie beds
participated in the deformation which the Paleozoic rocks have suffered,
fixes the date of the principal deformative movements of the Rocky
mountains as post-Laramie.
The thickness of the Laramie is estimated at 1000-5000 feet, exclu-
sive of the transition (Mesozoic-Cenozoic) beds to be mentioned below.
Some parts of the series, e.g., the coal, are such as to indicate slow accu-
mulation.
Various points in the structure and surface relations of the Cre-
taceous of Colorado are illustrated by Figs. 396 to 398.
FIG. 396. — Section of Cretaceous in the plains of Colorado, showing the several for-
mations dipping at a low angle toward the mountains and overlain in that direc-
tion by later Eocene formations. Kd, Dakota formation; Kc, Colorado formation;
Kp (Pierre) and Kid (Trinidad), Montana series; Kl, Laramie; Epc (Poison Canyon
formation) and Ech (Cuchara formation) Eocene (?). Length of the section, about
15 miles. (Walsenburg, Colo., folio, U. S. Geol. Surv.)
In a considerable area in northeastern Wyoming, and in a large
area farther north,1 some of the Laramie lignite has been burned. The
1 Allen, Proc. Boston Soc. Nat. Hist., Vol. XVI, p. 246, 1874; also Bastin, Jour,
of Geol., Vol. XIII, p. 408. These phenomena were also noted and correctly inter-
preted by Lewis and Clarke. See report of their expedition.
154
GEOLOGY.
burning was relatively recent, and locally is still in progress. The firing
appears to have taken place on the sides of hills and valleys where
the lignite outcrops. Back from the slopes where the outcrops occur,
chimneys or vents appear to have sometimes developed, probably along
joints, leading up from the burning coal to the surface, giving rise to
" pseudo-volcanoes/7 The burning was accompanied by fusion, semi-
B
FIG. 397. — Map and section showing the position and relations of the several mem-
bers of the Cretaceous system, and the effect of a lava cap in the prevention of
erosion and in the development of mesas. Kp (Pierre formation) and Ktd (Trini-
dad formation), Montana series; Kl, Laramie series; Nb Neocene basalt. The sec-
tion is along the line A B of the map. (Hills, Elmoro, Colo., folio, U. S. Geol. Surv.)
fusion, and baking, resulting in lava-like slag and brick-red banks of
indurated clay. The former has had, and is still having a notable
effect on the details of the topography developed by wind and water,
while the latter gives striking color to the landscape. Incipient meta-
morphism accompanied the heat developed by the combustion.
Transition beds between Mesozoic and Cenozoic. — In general, the
Laramie is conformable with the Montana below, as the preceding
statements imply, and unconformable with the Eocene (Tertiary)
THE CRETACEOUS PERIOD.
155
above. The break between the Laramie and Eocene is locally a great
one, — has even been regarded as one of the greatest breaks recorded
in the strata of the continent.1 Locally, however, the association
FIG. 398. — Map of a small area in Colorado, showing the outcrops of faulted Cre-
taceous formations. Kd, Dakota; Kys (Graneros shale), Kgn (Greenhorn lime-
stone), Kcr (Carlisle shale), Kt (Timpas shale), and Ka (Apishapa shale), Colorado
series; Kp (Pierre shale), Montana series; Tri, igneous rocks of Tertiary age.
(Hills, Walsenburg, Colo., folio, U. S. Geol. Surv.)
of the Laramie and Eocene is so intimate that agreement concern-
ing the reference of certain beds, and even thick formations, has not
been reached. Within what has often been called the Laramie series,
there are local unconformities. Where these are slight, they prob-
ably have little significance in determining the classification of the
beds. Slight unconformities are common in the Pennsylvanian system
of the east, with which this series is most nearly allied in genesis. But
1 Emmons, Orographic movements of the Rocky Mountains. Bull. G. S. A.,
Vol. I, p. 285.
156
GEOLOGY.
there seems to be one unconformity which is neither slight nor local.
The beds above and below it have sometimes been known as the
Upper and Lower Laramie respectively. In Colorado the beds above
the great unconformity have also been called post-Laramie,1 and have
sometimes been classed with the Cretaceous, and sometimes with the
Tertiary. They include the Arapahoe (below) and Denver formations.
FIG. 399. — An outcropping ledge of clay, hardened by the burning of the coal-bed
below. Except in the immediate vicinity of the burnt-out coal-bed, the clay
is not indurated. Near Buffalo, Wyo. (Blackwelder.)
The Arapahoe formation is of fresh-water (or subaerial) origin, and
500 or 600 feet thick. The Denver formation, also of non-marine origin,
has a maximum thickness of more than 1400 feet, the lower part being
derived chiefly from andesitic lavas. The Ohio and Ruby formations
in another part of Colorado2 (2700 feet thick), and the Livingston
formation of Montana,3 as well as local formations elsewhere,4 occupy
the same stratigraphic position. The Livingston formation contains
brackish-water fossils below and fresh-water forms above.5
1 Geology of the Denver Basin of Colorado, Mono. XXVII, U. S. Geol. Surv.
2 Anthracite and Crested Butte folio, U. S. Geol. Surv.
3 Iddings and Weed, Livingston and Three Forks, Mont. , folios, U. S. Geol. Surv.
4 Cross, Am. Jour. Sci., 3d series, Vol. XLIV, 1892; pp. 19-42; also Mono. XXVII,
p. 213 et seq., and Hills, Proc. Colo. Sci. Soc., Vol. Ill, 1891, p. 359-458.
6 Cross, Mono. XXVII, U. S. Geol. Surv., p. 221.
THE CRETACEOUS PERIOD.
157
Pleistocene
West Elk breccia
Ruby formation
Ohio formation
Laramie series
Montana series
Colorado series
Dakota formation
Jura-Trias
1
£
I
Maroon
conglomerate
Weber limestone
Mississippian
Ordovician
Cambrian
Archean
.2 fl
Bozeman
Sphinx conglom-
erate
Livingston series
Laramie series
Montana series
Colorado series
Dakota formation
Ellis formation
Quadrant forma-
tion
Madison limestone
03 o>
rf\ *^
w
T-
158 GEOLOGY.
In Colorado the amount of erosion between the epoch of the Lara-
mie proper and that of the Arapahoe formation is thought to have
been very great. Cross estimates it to have been 14,000 feet.1 The
time involved must, therefore, have been long. Between the Arapa-
hoe and the Denver formations there is a lesser, though considerable
unconformity, and the interval represented by it witnessed the occur-
rence of igneous eruptions on an extensive scale. It was from the
lavas extruded at this time that the lower part of the Denver forma-
tion was derived.
Traced eastward, the Denver beds pass beneath Miocene beds.
Stratigraphically, therefore, there is no reason why the Arapahoe and
Denver formations should not be referred to the Eocene. The fossil
plants of the Denver formation, of which something like 150 species
have been identified, are consistent with this interpretation. But
few species are common to the Denver and Laramie of Colorado, while
an equal proportion are common to the Denver and the Eocene of other
localities. The meager Arapahoe flora is more closely allied with the
Denver flora above than with the Laramie flora below. The inver-
tebrate fauna of the Denver beds is little known, and the identified
species are common to both Laramie and Eocene. The vertebrate
fauna has distinct Mesozoic affinities, and has been the chief reliance
in classing the Arapahoe and Denver formations with the Laramie.
If the presence of saurian fossils demonstrates the Cretaceous age of
the beds containing them, the Arapahoe and Denver beds are Creta-
ceous; but every other consideration seems to point rather to their
reference to the Early Tertiary.2 After the deposition of the Laramie
below, and before the deposition of the Arapahoe and Denver beds,
there were great orographic changes, a long interval of erosion, and the
initiation of the protracted period of vulcanism which marked the
close of the Mesozoic. These physical changes were accompanied
by marked changes in vegetation, and these changes had been accom-
plished before the deposition of the Denver beds. The great physical
changes which inaugurated the changes in life appear to have taken
place before the Arapahoe formation was deposited. Their effects had
distinctly modified plant life by the time the Denver beds were de-
posited, but they appear to have had less effect on the vertebrate
JOp. cit., p. 217.
2 This whole question is well discussed by Cross and others in the monograph cited.
THE CRETACEOUS PERIOD. 159
life of the west, perhaps because conditions were not yet favorable
for the incoming of the mammalian life from the regions where it
originated.
The Livingston formation of Montana, consisting of brackish- and
fresh-water sediments, with some intercalated volcanic agglomerates
and breccias, rests unconformably on the (Lower) Laramie, and cor-
responds in its general relations with the Arapahoe and Denver forma-
tions. Its sediments were largely derived from the older sedimentary
rocks which seem not to have contributed to the earlier Mesozoic for-
mations, indicating post-Laramie-pre-Livingston deformation in this
region. The Livingston flora resembles that of the Eocene, and the
formation underlies fresh-water Eocene beds conformably. In some
parts of Wyoming, on the other hand, beds thought to have been
deposited at the same time as the Denver, Arapahoe, and Livingston
formations are said to be a part of the inseparable Laramie series.1
The thickness of these formations, especially that of the Livingston,
is very great, being estimated at 7000 feet.2 Even if the sediments
accumulated rapidly, as their nature indicates, this great thickness shows
that the epoch was a long one.
Coal. — The Cretaceous is preeminently the coal period of .the
west. Coal-beds occur in every one of its principal divisions in this
part of the continent. The total amount of coal, which is chiefly
in the Laramie series, is comparable to that in the Pennsylvanian
system, though the Cretaceous coal is not now so accessible, and its
quality is inferior. It is estimated that along the east and west bases
of the Rocky Mountains there are more than 100,000 square miles
of coal-bearing lands, and Colorado alone is estimated to have 34,000,-
000,000 tons of available coal,3 most of which is Cretaceous. The
coal is largely lignite, though in Colorado not a little of it has been
advanced to coking bituminous coal, and even to anthracite.4 Anthra-
cite referred to the Laramie also occurs farther south in localities where
it has been affected by intrusions of igneous rock. The areas of Laramie
coal are indicated in Fig. 241.
1 Stanton and Knowlton, Stratigraphy and Paleontology of the Laramie and
Related Formations in Wyoming. Bull. G. S. A., Vol. 8, pp. 127-156.
2 Weed and Iddings, Livingston, Mont., folio, U. S. Geol. Surv.
3Storrs, 22d Ann. Kept. U. S. Geol. Surv., Pt. III.
4 See Anthracite-Crested Butte folio, U. S. Geol. Surv.
160 GEOLOGY.
Thickness of the (Upper) Cretaceous system. — The maximum
thicknesses of the Cretaceous series are something as follows: The
Laramie (including the Livingston), about 12;000 feet; the Montana,
8700 feet; the Colorado, at least 3000 feet; the Dakota, about 300
feet. From these figures it will be seen that the Cretaceous system
is comparable in thickness to the systems of other periods. It should
be remembered, however, that these thicknesses represent maxima.
In the Black Hills, the Cretaceous has in some places a thickness of no
more than 1000 feet. In the Cinnabar Mountains (Montana), 4000
to 5000 feet; in the vicinity of Denver, about 13,000 feet; in Utah,
about 10,000 feet; in Kansas, 1000 to 1300 feet; in New Mexico, 3500
feet; in Manitoba, where the strata rest on the Devonian, 2000 feet,
and along the Northern Rockies in Canada, about 10,000 feet.1 But
even these figures are much greater than those for most of the systems
of the Paleozoic periods, over the larger part of the area where they occur.
The Pacific coast.2 — On the Pacific coast, the Cretaceous system
is represented by the marine beds which constitute the Chico series,
which, at the time of its origin, probably extended along the coast
from Lower California to the Queen Charlotte Islands. The series is
found largely in great structural valleys, which were formed in pre-
Cretaceous times.3 That part of the system which has escaped erosion
has a thickness of 4000 feet in some parts of California. The Chico
series rests on the Shastan or Comanchean unconf ormably in the southern
part of the Coast Range of California,4 and overlaps the Shastan
system at other points, resting on the Jurassic in the Sierras, and on
Paleozoic formations in southern California.5 In some places the
Chico series rests on the Knoxville formation, the Horsetown formation
being absent.6 Farther north, the Chico series sometimes rests on
the Shastan (Comanchean) system with apparent conformity, thus afford-
ing a local exception to the relation which generally subsists between
the two systems. In some parts of the Klamath Mountains, it rests
on schists of Devonian or greater age. In some parts of Oregon, the
1 Am. Kept. Geol. Surv. Can., Vol. I. (N. S.), p. 69 B.
2 See papers of Diller, Stanton, and Turner, cited under the Lower Cretaceous
(Shastan), p. 122.
3 Anderson, Proc. Cal Acad. Sci., Third Series, Vol. II, Pt. I.
Fairbanks, Jour, of Geol., Vol. Ill, p. 426.
5 Fairbanks, Am. Jour, of Sci., Vol. XLV, 1893, p. 478.
6 Anderson, op. cit.
THE CRETACEOUS PERIOD. 161
Chi co is wanting where the Lower Cretaceous is present.1 In British
Columbia, the Shastan period seems to have been inaugurated by
subsidence, but as the period progressed the area of land increased
till the sea failed to cover the Cordilleran belt.2 Formations younger
than the Dakota are not known in British Columbia between the Coast
range and the Selkirks,3 but along the coast there are formations cor-
related with the Colorado and Montana. Upper Cretaceous formations
are also known in western Alaska.4 In Vancouver Island, the Chico
is reported to be coal-bearing.
The relations between the Chico beds and the Cretaceous formations
of the interior have not been determined but the remaining portions
FIG. 402. — Section showing the position of the Cretaceous beds in western Oregon.
Mg, meta-gabbro of unknown age; sp, serpentine; as, amphibolite schist; Jr,
Jurassic (?); Km (Myrtle formation), Cretaceous, and Kmw, lentils of limestone
in the Myrtle formation; Eu (Umpqua formation), Eocene; Ed, Eocene diabase.
(Diller, Roseburg, Ore., folio, U. S. Geol. Surv.)
of the former do not appear to represent the latest part of the system.
The region may have emerged before the closing stages of the period,
or the beds then deposited may have been removed by erosion.
Climate. — The climate of North America during the Cretaceous
period seems to have been uniform and warm throughout a great range
of latitude. In Greenland, Alaska, and Spitzbergen, the climatic
conditions seem to have been similar to those in Virginia. Toward
the close of the period, however, the climate seems to have been cooler,
for the Laramie flora is a temperate, rather than a tropical one.
CLOSE OF THE PERIOD.
The Cretaceous period is commonly said to have been brought to
a close by a series of disturbances on a scale which had not been equaled
since the close of the Paleozoic era, and perhaps not since the close
of the Algonkian. These changes furnish the basis for the classifi-
cation which makes the close of the Cretaceous not the close of a
1 Roseburg, Ore., folio, U. S. Geol. Surv.
2 Dawson, loc. cit.
3 Dawson, Bull. Geol. Soc. Am., Vol. XII, p. 77.
4Schrader, Bull. Geol. Soc. of Am., Vol. XIII, p. 247.
162 GEOLOGY.
period merely, but the close of an era as well. While these changes
are commonly said to have taken place at the close of the Cretaceous,
it is probably more accurate to say that they began late in the Upper
Cretaceous, and continued into the succeeding period. The close of
the Cretaceous may be said to have been the time when these changes
first made themselves felt profoundly. They consisted of deformative
movements, a part of which were orogenic, and of igneous eruptions
on an unprecedented scale.
General movements. — In the closing stages of the period, the sea
which had lapped over the Coastal plain of the Atlantic and Gulf was
withdrawn toward the abysmal basin. Data now in hand point to
the emergence of the eastern Gulf region in advance of the Atlantic
coast, while the emergence of the Texan area was probably still later,
and this implies that the changes were not due wholly to variations
of the sea, but in part at least to differential warpings of the coastal
belt. The Appalachian mountains, which had their first period of
folding during the Permian, and which had been reduced to a pene-
plain by the beginning of the Cretaceous, were bowed upward at some
later time, and this second period of growth seems to fall within the gen-
eral period of deformation here under consideration. This later move-
ment was chiefly vertical, while the Permian deformation was primarily
horizontal.
In the western interior, the prolonged period of crustal oscillation
which marked the Laramie, marked also the beginning of the end
of the Cretaceous. By the close of the Laramie, the sea had with-
drawn from the extensive area occupied by the Great plains, and
from large areas in the mountains west of the plains. It is probable,
indeed, that most of the Cordilleran region was elevated bodily at
this time, though not to its present height. Great areas which had
been submerged were however brought above the critical level, and
the movements were, therefore, recorded. Records of similar move-
ment in some other regions where they probably took place are want-
ing, or the record is less clear; but it is probable that the eastern
interior underwent changes of level, relative to the sea, at this time.
Enough is known to make it clear that a large part of the continent
was affected by the general withdrawal of the sea.
Orogenic movements. — The development of mountains by folding
was probably in progress in the last stages of the Cretaceous period,
THE CRETACEOUS PERIOD. 163
from Alaska on the north, to Cape Horn on the south, more than a
quarter of the circumference of the earth. Similar movements prob-
ably affected the Antillean mountain system/ lying between the south-
ern end of the Cordilleran and the northern end of the Andean systems,
for in several of the Antillean islands, later formations rest unconf orm-
ably on the deformed Cretaceous beds. Locally, as where the Eocene
rests conformably on the Laramie, the disturbances of this time are
not clearly distinguishable from those of later date, which increased
the deformation initiated at this time. Some of the folded ranges
of the Cordilleran system began their history at this time; others had
a new period of growth, and still others date from a later period. Yet
the close of the Laramie was, par excellence, the period of orogenic
movement in the western part of North America. The Rocky Mountain
system may be said to have had its birth at this time. That the exist-
ing mountains are not older is shown by the deformation of the Lara-
mie beds along with those of greater age. That this folding was not
younger is shown by the lack or slightness of deformation of the Ter-
tiary beds in the same region.
North of the United States, the site of the Laramide range (the
continuation of the Rockies of the United States) had been a tract of
great deposition through Paleozoic and Mesozoic times. In it, sedi-
mentary beds had accumulated to a thickness, which, by the usual
methods employed in such cases, is estimated at 50,000 feet.c At
this time the strata, doubtless already inclined and bowed as inci-
dents of deposition, were tilted, folded, and faulted into the Lara-
mide range. The thrust producing the folding and faulting appears
to have come from the west, as implied by the position of the over-
thrusts. The height of the moun tarns developed in this region at
this time is estimated at 20,000 feet. The mountains have since
undergone further elevation, and had erosion not reduced them, it is
estimated that their present height would be 32,000 to 35,000 feet.
It has been calculated that in the Laramide range a surface belt 50
miles wide was reduced to one half that width.3 Estimating the aver-
age height of the faulted tract at about half the maximum height,
1 Hill, Nat. Geog. Mag., Vol. VII, p. 175.
2Dawson, Science, Vol. XIII, 1901, p. 401, and Bull. Geol. Soc. Am., Vol. XII,
p. 88.
3Dawson, Bull. Geol. Soc. Am., Vol. XII, p. 87.
164 GEOLOGY.
the thickness of the crust involved in the deformation would be about
three and a half miles.
Within the United States, comparable, if less extensive, elevations,
deformations, and faultings took place along the southward continu-
ation of the Laramide range. At every point where the Rockies
have been studied, the post-Laramie deformation has been found to
overshadow both earlier and later deformations. Dana has called the
whole chain of mountains which received its initiation at this time, the
Laramide system.1
West of the Rockies, there were also orogenic movements along
more or less parallel tracts. Many of the ranges of the west have
not been studied in detail, but most of those whose history has been
worked out show deformation at this time. Here may be mentioned
many of the mountains of Colorado 2 and Wyoming, and the Wasatch
and Uinta Mountains of Utah. In northern California and southern
Oregon there were deformations, as shown by the unconformity between
the Upper Cretaceous and the Eocene, but the deformation here seems
to have been less intensive than farther east. Locally, however, it is
thought to have been sufficiently violent to develop the anomalous sand-
stone dikes of northern California (Fig. 417, Vol. I) 3. In British Columbia
west of the Gold range, there had been a broad tract of deposition
250 miles in width. The beds (largely igneous) which had accumu-
lated in this syncline, estimated, in the usual way, to be 40,000 feet
(maximum) in thickness, suffered deformation at this time. Meta-
morphism here was so intense as to make the separation of Archean
and later rocks impracticable.4 As in the Laramide range, the relief
produced was great. In intensity of tangential thrust, the disturb-
ances of this time were in contrast with those of other periods through-
out most of the area between the Sierras on the west and the Great
plains on the east.
Faulting. — The mountain formation at the close of the Cretaceous
period was accompanied by faulting on a somewhat extensive scale
throughout the region of movement, though the faulting of this
1 Dana, Manual of Geology, 4th ed.
2 See folios of the U. S. Geol. Surv. for Colorado, Wyoming, and Montana. Also
Emmons, Bull. Geol. Soc. of Am., Vol. I.
3 Diller, Bull. Geol. Soc. Am., Vol. I, p. 411; and Downieville, CaL, folio, U. S. GeoL
Surv.
4 Dawson, loc. cit.
THE CRETACEOUS PERIOD.
165
time cannot always be distinguished from faulting of later date.
In the Rocky mountains of British Columbia, one overthrust fault
ChiefMt
FIG. 403. — Section in northern Montana, showing Proterozoic rock, A, thrust over
Cretaceous, K. Subsequent erosion has removed much of the overthrust beds,
but Chief Mountain is a remnant of them. The extent of the overthrust is
unknown.
has been located which crowded the Cambrian rocks obliquely
up over the Cretaceous. The horizontal displacement is estimated to
FIG. 404.— Chief Mountain. (Willis, U. S. Geol. Surv.)
be as much as seven miles,1 while the throw is as much as 15,000
feet. Near the national boundary, the displacement of what appears
to be the same fault crowded the Proterozoic up over the Cretaceous2
by a movement of equal magnitude (Fig. 403). The exact date of
1 McConnell, Geol. Surv. of Canada, Vol. II, Kept. D, p. 33, 1886.
2 Willis, Bull. Geol. Soc. of Am., Vol. 13, pp. 307, 331-5.
166 GEOLOGY.
these faults has not been determined, but they occurred during the
general period of disturbance inaugurated at the close of the Upper
Cretaceous. The position of the Cretaceous near Livingston, Mont.,
is shown in Fig. 405, while the effect of faulting on outcrops in the
plains of Colorado is shown in Fig. 398.
FIG. 405. — Section showing position of Cretaceous beds at one point in the vicinity
of Livingston, Montana. ^ = Archean; €, Cambrian (Gallatin and Flathead
formations); D, Devonian (Jefferson formation); C, Carboniferous (Quadrant
and Madison formations); «7, Jurassic (Ellis formation); Kd, Dakota formation;
Kc, Colorado series; Km, Montana series, and Kl, Laramie series; 66r, basic igne-
ous rock, and apt, acidic rock. Length of section about 11 miles. (Livingston,
Mont., folio, U. S. Geol. Surv.)
With present data it is impossible to interpret all the deformations at this
time in a strictly inductive way, and differences of opinion remain appropriate.
A composite interpretation may, however, be indicated. The facts that have
just been given relative to folding and overthrust seem to indicate clearly a lateral
movement of the crust, attended by a sub-crustal shear, and a folding and
faulting of the crustal zone. Using the methods of estimate previously set forth
(Vol. II, p. 125), the thickness of crust thus sheared was three or four miles. The
fault throw given above (15,000 feet) is what would naturally follow if a crust
three miles thick were thrust over the normal surface. Dawson's estimates
of shortening and height of the folded portions are closely in harmony with this
very instructive faulting phenomenon.
So far as the American continents are concerned, the folding-faulting move-
ment, here interpreted as a shear movement of a shell three or four miles thick,
was essentially confined to the western border, but it extended the length of both
North and South America. This is probably typical of the great mountain-
making movements of post-Cambrian times. Folding seems to have been con-
centrated along one great belt in each continent for a given continuous direc-
tion. This folding is thought to imply shrinking of the earth-body. Daw-
son's estimate of the shortening involved in the Laramide range alone implies
a descent of the surface of four miles. If the shortening involved in the parallel
ranges west of the Laramide range be added, the descent of the surface was
probably as great as the extreme upward folding of the range, as maintained
by Suess.
The shrinkage which is implied by this folding was probably first and chiefly
felt by the ocean basins, for reasons set forth previously. The primary effect of
this is thought to have been some increase in their capacity as basins, and hence
THE CRETACEOUS PERIOD.
167
the withdrawal of the sea from its epicontinental extension. We have avoided
calling the emergence of the land an uplift on this account. It is not, as we
conceive, a mere matter of relativity. The initial act lies with the ocean bot-
tom, and the water seconds this by an actual withdrawal.
But this is not thought to complete the sequence of events. The continental
platform is warped in its various parts as it follows the ocean basins in sinking.
This seems to have two phases at least. The one is expressed in the facts already
FIG. 406. — Map and section showing relations of igneous rock to the Cretaceous for-
mations in the Crazy Mountains of Montana. The section is along the line AB
of the map. Klv, Livingston formation; di, diorite; gr, granite. The especial
feature of the map is the extraordinary number of dikes radiating from the cen-
tral intrusion, di. The shaded area about di represents the zone of contact meta-
morphism about the intrusion. Length of section about 20 miles. (Livingston
and Little Belt, Mont., folios, U. S. Geol. Surv.)
168 GEOLOGY.
noted, that the epicontinental seas withdraw unequally in different regions,
as for example from the eastern Gulf region earlier than from the Atlantic or
the western Gulf coasts. The other phase is expressed in the vertical upbowing
of certain tracts, usually old mountain tracts, such as the Appalachian in the
present case. In general, those borders of a continent that do not suffer crus-
tal shear and folding, are apt to be bowed in this way as a part of the deeper
deformation of the continental segment, resulting from its squeezing between
the adjoining oceanic segments, as heretofore explained.
The deformations at the close of the Cretaceous seem to have been of the
typical earth-body type, expressing themselves in all the characteristic phases —
basin sinking, sea withdrawal, crustal shear, folding and faulting, vertical bowing,
and general warping.
Igneous eruptions. — The close of the Cretaceous was attended by
exceptional igneous activity, the eruptions beginning late in the Laramie
epoch. It was during this period of igneous activity that many of
the great bodies of igneous rocks of the west, whether extrusive or
intrusive, were forced up. Fig. 406 shows the relation of igneous intru-
sions to Cretaceous beds in the Crazy mountains of Montana. It may
be noted in passing, that igneous eruptions occurred in other lands
at the same or about the same time, among them the lava-flows of
India, the greatest on record.
UPPER CRETACEOUS OF OTHER CONTINENTS.
Europe. — As shown by the distribution of the Upper Cretaceous
strata of Europe, extensive transgressions of the sea occurred at the
beginning of this period. What is now the central plateau of France
was land during the Earlier Cretaceous (Comanchean) period, but was
largely submerged during the Later. So also was much of the great
land area of the Earlier Cretaceous period lying northeast of the Paris
basin. In Saxony, Silesia, and Bohemia, the Upper Cretaceous sys-
tem is widespread, and rests on Paleozoic strata, indicating, or at
least suggesting, that the submergence was more general for this
region than in any earlier period of the Mesozoic. During the closing
stages of the Upper Cretaceous, fresh-water beds appear in localities
(Alpine region) where marine sedimentation had been in progress,
showing that the region was by this time affected by the movements
which were to mark the close of the era.
Russia was more extensively under water during the Earlier Cre-
taceous period than most other parts of Europe, but even here the
THE CRETACEOUS PERIOD. 169
Upper Cretaceous beds spread beyond the Lower, having notably
greater extension both in the central and southern parts of the country.
In central Russia, the uppermost beds of the system have little develop-
ment, though they are of importance farther south, covering wide
areas south of latitude 55°.
As in the case of the Lower Cretaceous, the Upper Cretaceous of
southern Europe is notably unlike that of the central province. While
FIG. 407. — Sketch-map of Europe showing the relations of land and sea (shaded area)
during the Cenomanian epoch. (After de Lapparent.)
clays and marls are common, limestone is still the dominant formation
in the southern province, where clear waters still prevailed. From a
characteristic genus of fossils, much of the limestone of the system
is known as the Hippurite limestone.
The most notable petrographic feature of the Upper Cretaceous
system of Europe is the abundance of chalk. Both in England and
France it attains an aggregate thickness of several hundred feet, though
much of it is far from pure. It grades into marls and clays on the
one hand, and into sandstone on the other. The lowest chalk-beds occur
170 GEOLOGY.
in the Cenomanian series (p. 109), and the same sort of rock constitutes
a part of each of the succeeding series. Chalk is, however, by no means
co-extensive with the system, for it has little development outside of
the Anglo-French area. The name " Cretaceous/ ' therefore, as gen-
erally used, is as inappropriate as a name could well be, having no appli-
cability to the Lower Cretaceous, and fitting only a relatively small
area of the Upper. Even within the areas where chalk occurs, it is
not everywhere the dominant sort of rock.
Greensand occurs in the Upper Cretaceous as well as in the Lower,
and iron-ore beds, similar in character and origin to those of the Lower
Cretaceous, occur in the Upper. In this case, the ore was derived
from the Lower Cretaceous.
The Danian of Europe, sometimes unconformable on the lower
parts of the system, is perhaps to be looked upon as recording the
transition from the Mesozoic to the Cenozoic.1 Its fossils, especially
those of the plants, have distinct Cenozoic affinities.
Asia. — The submergence of Europe and North America at the
beginning of the Upper Cretaceous finds its parallel in other conti-
nents. There are extensive areas of Upper Cretaceous (Hippuritic
limestone) in southwestern Asia (Arabia, Persia, Afghanistan, Beloo-
chistan, the Himalayas, and Tibet), closely connected with those of
Europe on the one hand, and with those of North Africa on the other.
The Himalayan region seems to have been still beneath the sea, for
Upper Cretaceous formations are found here and there in the mountains
at great elevations. Upper Cretaceous greensand has recently been
found in the Salt Range of India.2 South of these marine beds there
appears to have been a large tract of land, including much of India,
which has been thought to have stretched southwest so as to unite
that peninsula with Africa, though the configuration of the sea-bottom
does not lend this view much support. Upper Cretaceous beds occur
also on the eastern coast of China, and in Japan. In many of these
places, they rest on formations older than the Lower Cretaceous, and
therefore record geographic changes dating from the beginning or early
part of the Upper Cretaceous period. On the other hand, northern
Asia, which was largely submerged during the Earlier Cretaceous period,
was largely land during the Later.
1 Geikie, op. cit., p. 1201.
2Seeley, Geol. Mag., 1902, p. 471.
THE CRETACEOUS PERIOD. 171
It was late in the Upper Cretaceous that the extensive lava-flows
of the Deccan occurred. These lava- flows, 4000 to 6000 feet in thick-
ness, cover an area of something like 200,000 square miles, and are
perhaps the most stupendous outflows of lava recorded in the earth's
history. The lavas he on the eroded surface of the Cenomanian
and are inter bedded, locally, with sediments of the •" uppermost
Cretaceous." l The fossils of these interbedded sediments show that
the lavas were subaerial.
Africa. — In northern Africa the Lower Cretaceous beds were con-
fined to the northwestern mountains, but the Upper Cretaceous beds,
which overlie the Lower unconformably,2 spread southward, and cover
most of the desert, indicating great submergence in the north African
region at the close of the Earlier Cretaceous period. South of the
Sahara, no Upper Cretaceous beds are known except in a few small
areas about the coast. Here they rest on crystalline schists, with no
Lower Cretaceous beds beneath, or, so far as known, near.
South America. — In South America, the sea invaded eastern Brazil,
where marine Upper Cretaceous beds cover and overlap the non-
marine Lower Cretaceous. In some parts of Brazil, however, the
Upper Cretaceous is represented by fresh-water beds only. Farther
west, marine Upper Cretaceous beds (Senonian) rest unconformably
on Lower Cretaceous formations, and form the summits of most of the
eastern Andes, frequently occurring up to altitudes of 14,000 feet,
and sometimes considerably higher. Upper Cretaceous beds also
occur in southern Patagonia.3 There appears to have been great
volcanic activity in the Andean system (Chili and Peru) during the
Late Cretaceous.
Australia. — The phenomena of Australia are in harmony with those
of the other continents. The Upper Cretaceous beds are wide-spread-
and locally rest on formations older than the Lower Cretaceous. Fur-
thermore, the Upper Cretaceous (the Desert Sandstone) is in many places
unconformable on the upturned and denuded surface of the Lower
Cretaceous, showing that there were deformative movements, as well
as movements which changed the relations of sea and land, after the
1 Medlicott and Blanford, Geology of India; 2d ed. by R. D. Oldham; cited
by Geikie, Text-book of Geology, 4th ed., Vol. II, p. 1209. Also Stoliczka, Paleo.
Indica., Ser. I, III, V, VI, and VIII (1861-1873).
2 Kayser, Geologische Formationskunde, p. 443.
"Wilchens, Centralblatt fur Mineralogie, etc., 1904, p. 597.
172 GEOLOGY.
deposition of the Lower Cretaceous beds, and before the deposition
of the Upper. This recalls the relations of the Lower and Upper
systems in America. The Upper Cretaceous is represented in New
Zealand, where beds of coarse elastics, together with some greensand,
are found. There is also some coal in the system, which, as in some
parts of western North America, is not sharply differentiated from
the Tertiary. The Upper Cretaceous system is also represented in
central Borneo1 and Antarctica.2
In general it may be said that there was little marine sedimen-
tation in the Late Cretaceous period north of the parallel 60° north,
while the Jurassic and Lower Cretaceous systems are here more wide-
spread. Between the parallels of 20° and 60°, on the other hand,
the zone where marine Lower Cretaceous is but slightly developed,
the Upper Cretaceous system is widespread. Outside of China, the
Upper Cretaceous system is wanting over no considerable land-area
within these limits. In the equatorial and south temperate zones,
the Upper Cretaceous seas were also expanded much beyond the
limits of the waters of the preceding period.
Climate. — The fresh- water fossils of the Upper Cretaceous of cen-
tral Europe indicate a warm climate, comparable to that of Malaysia.3
In the eastern Alpine region and beyond, there is a conglomerate for-
mation (Flysch) which will be referred to in connection with the Eocene
system. The lower part of the formation is, however, Upper Creta-
ceous, and its constitution is such as to have suggested glaciation.
The suggestion has not been verified.
LIFE OF THE (UPPER) CRETACEOUS.
The Land Life.
The carbonaceous deposits which the Cretaceous vegetation con-
tributed to the latest Mesozoic series are quite analogous to those
of the Coal Measures of the late Paleozoic, and the Animikean
carbonaceous beds of the Proterozoic. They all seem to be expres-
sions of undrained conditions of the land, arising out of the initial
unbalancing of a base-level state, preliminary to a marked deforma-
tive movement. This, in the case of the Cretaceous, is more particu-
larly true of the closing epoch, the Laramie.
1Molengraaf, Geol. Mag., 1903, p. 170.
2 Weller, Jour, of Geol., Vol. XI., p. 413.
3 Neumayr, Erdegeschichte, Bd. II, p. 383.
THE CRETACEOUS PERIOD. 173
The vegetation. — At the opening of the (Upper) Cretaceous in America,
the angiosperms were in marked dominance, and during the period genera
now living became more and more abundant, giving to the whole a dis-
tinctly modern aspect. Extinct forms came to occupy a subordinate
place. Among these were Zamites, PodozamiteSj and Baiera, which
were common in the previous periods, but disappeared at the close
of the Cretaceous. Among the living genera that made their appear-
ance were Podocarpus, the dominant pine of the southern hemisphere,
Betula (birch, Fig. 408, g), Fagus (beech), Quercus (oak, Fig. 408, e),
Juglans (walnut), Myrica (tamarisk, mayberry, Fig. 408, 6), Arto-
carpus (bread-fruit tree), Platanus (plane-tree), Liriodendron (tulip-
tree, Fig. 408, a), Per sea (laurel), Cinnamomum (cinnamon), Acer
(maple), Ilex (holly), Liquidamber (sweet-gum), Hedera (ivy), Cornus
(cornel), Nerium (oleander), and Viburnum (wayfaring- tree, arrow-
wood, Fig. 408, /). Prominent among those that had come over from
the Lower Cretaceous were Ficus (Fig. 408, i), Sassafras (Fig. 408, h),
Magnolia (Fig. 408, c), and Sterculia (flame-tree, Fig. 408, d). Among
the gymnosperms, there was a notable development of the sequoias,
which now embrace the giant trees of California, and there were
advances among other conifers. The modern genus Cycas was present,
and the ginkgo had some prominence, though never a leading type.
Worthy of special note was the presence of genera in Europe and the
United States which are now confined to the southern hemisphere,
as Eucalyptus and the pine above mentioned. Some of these remained
in the northern regions into the early Ceriozoic.
Previous to this period, and in its earlier stages, monocotyledons
played but an insignificant part in the floral record, but they now
began to assume importance. Many palms were present before the
close of the period, some of which at least were closely allied to existing
forms. Their presence in northern latitudes implies a mild climate.
Of even more interest, because of their relations to the evolution of
grazing animals, was the appearance of grasses, which do not, how-
ever, appear to have attained prominence thus early. It is worthy of
remark here that the Cretaceous revolution in vegetation was not
only great as a phytological event, but was at least susceptible of
profound influence on zoological evolution, for it brought in new and
richer supplies of food in the form of seeds, fruits, and fodder. At
present, neither the ferns, equiseta, cycads, nor conifers furnish food
174
GEOLOGY.
FIG. 408. — A GROUP OF FOSSIL LEAVES OF TYPICAL CRETACEOUS PLANTS FROM THE
DAKOTA HORIZON: a, Liriodendron giganteum Lesq.; 6, Myrica longa Heer; c,
Magnolia pseudo-acuminata Lesq.; d, Sterculia mucronata Lesq.; e, Quercus sus-
pecta Lesq.; /, Viburnum incequilaterale Lesq.; g, Betulites westi, var. subinte-
grifolius Lesq.; h, Sassafras subintegrifolium Lesq.; i, Ficus incequalis Lesq.
THE CRETACEOUS PERIOD. 175
for any large part of the animal life. The seeds of the conifers are
indeed much eaten by certain birds and rodents, but their foliage
is little sought by the leading herbivores. The introduction, there-
fore, of the dicotyledons, the great bearers of fruits and nuts, and of
the monocotyledons, the greatest of grain and fodder producers, was
the groundwork for a profound evolution of herbiverous and frugiverous
land animals, and these in turn, for the development of the animals
that prey upon them. A zoological revolution, as extraordinary as
the phytological one, might naturally be anticipated, but it did not
immediately follow, so far as the record shows. The reptile hordes
seem to have roamed through the new forests as they had through
the old, without radical modification. The zoological transformation
may have been delayed because animals suited to the proper evolu-
tion had not then come into contact with the new vegetable realm;
but with the opening Tertiary, the anticipated revolution appeared,
and swept forward with prodigious rapidity.
The new flora became very widely and uniformly distributed.
Not only was the European flora essentially the same as the Ameri-
can, but there was a close resemblance between the flora of Mid-Green-
land (70°-72° Lat.) and that of Maryland and Virginia. That there
should be no essential variation in a stretch of 35° of latitude implies
climatic conditions of remarkable uniformity. The flora, in its gen-
eral nature, was nearest to that which now flourishes at about 30°
latitude, that is, a flora of a sub-tropical type. As this seems to
have been attended by low relief of the land, widely extended epi-
continental seas, extensive calcareous deposition, and slow consumption
of carbon dioxide in rock solution and carbonation, there was present
the combination of conditions regarded as favorable for a mild, uni-
form climate.
The land animals. — The terrestrial animals continued to bear the
same general aspect as they did in the Jurassic and Comanchean. In
Europe, where the sea made great inroads upon the land, there was
some decline in the abundance, variety, and gigantic proportions of
the land animals, but in America, where the incursion of the sea was
more limited, and where the post-Jurassic deformation of the west
made some compensation for sea-advance elsewhere, the land area
remained sufficiently large to permit the evolution of the reptilian
host to proceed with little restraint. On both continents, however,
176
GEOLOGY.
the aquatic reptiles seem to have been relatively the more favored,
and to have made the greater progress.
The dinosaurs. — These great reptiles still retained the dominant
place, but their pre-eminence was less marked than before. The
carnivorous forms (Theropoda) were less abundant and varied. Among
their representatives was the Lcelaps or Dryptosaurus, a leaping, kan-
garoo-like form with a length of 15 feet.
FIG. 409. — Spoonbill Dinosaurs of the Cretaceous (Hadrosaurus mirabilis Leidy) as
interpreted by Knight. (Osborn, Copyrighted by the Am. Mus. of Nat. Hist.)
The most singular dinosaurian development appeared in the Cera-
tops family of the herbivorous branch, particularly in the genus Tri-
ceratops or Agathaumus (Fig. 410). These were very large quadru-
peds, with enormous skulls which extended backwards over the neck
and shoulders in a cape-like flange. Added to this was a sharp, parrot-
like beak, a stout horn on the nose, a pair of large pointed horns on
the top of the head, and a row of projections around the edge of the
cape. One of the larger skulls measured eight feet from the snout
to edge of the cape. This excessive provision for defense was not
unnaturally accompanied by evidences of low mentality in the form
of a very small brain cavity. Marsh remarks that they had the largest
THE CRETACEOUS PERIOD.
Ill
FIG. 410. — Skeleton of Triceratops prorsus, Marsh. (U. S. Nat'l Museum.)
FIG. 410a. — Triceratops prorsus Marsh, from the Laramie Cretaceous. From a paint-
ing by C. R. Knight in the U. S. National Museum.
178 GEOLOGY.
heads and the smallest brains of the reptile race. They were doubt-
less stupid and sluggish.
The ornithopod division was represented by Trachodon, Claosaurus
(Fig. 411) and kindred genera. The posterior parts of all these were
strongly developed, the limbs were hollow, and their footprints indi-
cate that they walked in kangaroo-like attitude.
Turtles, lizards, snakes, and crocodiles. — Although it is confidently
believed that the Trionychia, or river turtles, one of the three or four
FIG. 411. — A Cretaceous Dinosaur of the ornithopod division, Claosaurus anncctens,
(Restored by Marsh.)
chief divisions of the Chelonia, had been differentiated long before,
the earliest known representatives of the group are from the Belly
River deposits of Canada. Of the true lizards which appeared in the
Triassic, the only other Mesozoic form known is one of small size and
uncertain affinities from the Laramie. True snakes made their first
appearance, so far as known, in the later part of the period, and all
were small. Among the crocodiles, the long-snouted teleosaurs (Tele-
orhinus) persisted, in North America at least, until well into the Cre-
taceous; but for the most part the order underwent a marked change
early in the period, developing into the modern type of crocodiles and
THE CRETACEOUS PERIOD. 179
gavials. A few small salamanders, of modern type, are known from
the late Cretaceous.
The Pterosaurs. — The flying reptiles made so distinct an advance
in specialization, that Williston regards them as having come to excel
all other volant vertebrate animals. Some attained a wing-spread
of perhaps 20 feet, and had great powers of flight. In the genera
Pteranodon and Nyctosaurus (Fig. 412) the development of the anterior
parts was disproportionately great, while the posterior parts were
very small and weak, so much so that it is doubtful whether they
FIG. 412. — A Cretaceous Pterodactyl, Nyctosaurus gracilis Marsh, about one-ninth
natural size, from Niobrara Cretaceous, Kansas. (Restored by Williston.)
could stand on their feet alone. That they had powerful and sus-
tained means of flight, is implied also by the occurrence of their remains
far from shore. In Cretaceous times, they were all short-tailed, and
for the most part toothless, though the toothed forms persisted for a
wnile. Their bills resembled those of modern birds, and they have
been styled the kingfishers of the Cretaceous seas. If these forms
were the sole ones, the pterosaurs might well be classed with the sea
life.
Terrestrial birds undoubtedly existed, but the record is negative,
while curious aquatic forms appeared, which will be treated under the
sea life.
The slight progress of the mammals. — The mammals thus far
recovered from the Belly River and Laramie Cretaceous deposits
180 GEOLOGY.
*
indicate little advance upon the Jurassic and Wealden forms. The
relics are fragments of bones, jaws, and teeth, .al1 of which seem to
represent marsupials or monotremes of small size. They appear to
have played a very inconspicuous part in the fauna of the period.
The Sea Life.
The sea saurians. — The ichthyosaurs and plesiosaurs which had
dominated the Jurassic sea lived on into the Cretaceous, but the ichthyo-
saurs almost disappeared soon after the beginning of the period, while
the plesiosaurs continued through it, attaining their highest develop-
ment and perhaps their greatest size. They had great diversity of
form, and were doubtless equally diverse in habit.
The sea serpents. — The aquatic branch of the scaled saurians
(squamata) attained great importance during this period, as veritable
sea serpents. The dolichosaurs, long-necked, lizard-like reptiles, were
present as early as the Comanchean period, and are not known to
have lived after the beginning of the (Upper) Cretaceous. They were
the forerunners and perhaps the direct ancestors of the pythonomorphs
(mosasaurians) (Fig. 413). The name implies that they were serpent-
FIG. 413. — A Cretaceous mosasaurid, Platacarpus coryphaeus, Cope, restored by Willis-
ton, from Upper Cretaceous, Kansas.
like in form, but this refers chiefly to the elongation and slenderness
of the body. The limbs were retained in less modified forms than
those of the ichthyosaurs and plesiosaurs, implying a less complete
adaptation to aquatic life. The mosasaurian family flourished in
the Cretaceous, and enjoyed a wide distribution, ranging from
North and South America to Europe and New Zealand. Their short
career seems to have ended with the period, and no direct descendants
are known. The plesiosaurs were notably more specialized than in
the early Jurassic (Fig. 413, a).
The sea turtles. — The first strictly marine turtles appeared in
Cretaceous times, and deployed into many and diverse forms. The
maximum size of the order was reached in the gigantic Protostega
THE CRETACEOUS PERIOD.
181
and the even greater Archelon. These were broad, flat forms, degene-
rate in having the carapace reduced to the ribs alone, and probably
covered with a soft skin, as are some living marine turtles. Archelon
FIG. 413a. — Trinacromerum osborni Williston. A mounted skeleton of a typical fish-
eating plesiosaur, 10 feet long. The elongate head and the shortened neck (Com-
pare Fig. 367) represent specialization characteristic of the late plesiosaurs (Wil-
liston). From the Niobrara of Kansas.
had a skull larger than that of a horse, and must have measured fully
twelve feet across the shell.
Following the fashion of the day, the rhynchocephalians gave
FIG. 414.— Champsosaurus, from the Laramie of Montana.
feet. (After Brown.)
maf
Length, about six
rise to a group of aquatic reptiles, by some considered of ordinal rank
(Choristodera) , represented in Europe and in North America by two
closely allied forms, Simoedosaurus and Champsosaurus (Fig. 414).
182 GEOLOGY.
The latter began in the Laramie epoch, and continued into the Eocene;
the former is known only from the Lower Eocene.
The sea birds. — In the long interval between the first known appear-
ance of birds in the Jurassic, and the later Cretaceous, when they re-ap-
peared, important changes took place, among which was the loss of
the elongate, bilaterally feathered tail. The Jurassic birds were ter-
FIG. 415. — Hesperornis regalis. Skeleton in U. S. National Museum from which
the restoration Fig. 415a was made. Sternum and two anterior cervicals sup-
plied by restoration. (Lucas.)
restrial, while the Cretaceous were aquatic. The Cretaceous birds-
belonged to two widely divergent classes, the one consisting of large
flightless birds (Hesperornis), the other of small birds of powerful
flight (I chihyornis) . The Hesperornis (Fig. 415), was a large, flightless,
highly specialized diver, with aborted wings and remarkable leg develop-
ment. The wings had almost vanished, a single bone only being left.
This implies that, following the evolution which had produced the
wings, there was a degenerative history long enough for them to dwindle
THE CRETACEOUS PERIOD. 183
almost to the point of extinction. Concurrent with this, and doubt-
less its cause, was an extraordinary development of the legs by which
they became not only very powerful, but their efficiency as paddles
was increased by the bones of the foot being so joined to those of the
leg as to turn edgewise in the water when brought forward. Not
only this, but, strangely enough, the legs were so joined to the body
frame as to stand out nearly at right angles to the latter, like a pair
of oars, instead of standing under the body as walking legs universally
FIG. 415a. — Restoration of the great toothed diver of the Cretaceous, Hesperornis,
by Gleeson, based on a skeleton in the U. S. National Museum. (From Lucas'
Animals of the Past; by permission of the Publishers, McClure, Phillips & Co.)
do.1 Apparently walking as well as flying had been abandoned, and
the organism was specialized for swimming and diving only. The head,
neck, and body were elongate and admirably shaped for plunging
through the water. Favored by the powerful specialized hind limbs,
the Hesperornis was doubtless a swift swimmer and an expert diver,
and must have been a formidable enemy to the sea life on which it
chose to feed. Its jaws were armed with teeth set in a groove in primi-
tive saurian fashion, and, like the jaws of snakes, were separable so
as to admit large prey. As these strange birds attained a length of
six feet in some cases, their victims may have embraced fish and rep-
tiles of considerable size. As they have been found in Kansas, Mon-
1 Lucas, Animals of the Past, 1901, pp. 81-85.
184
GEOLOGY.
tana, North Dakota, New Jersey, and England, they probably fre-
quented the continental waters somewhat widely, and belong more
to the sea life than to the land life from which they sprang.
The second type, Ichthyornis (Fig. 416), consisted of small birds,
scarcely larger than pigeons, and tern-like in aspect, endowed with great
powers of flight, and armed with teeth set in sockets. In contrast with
FIG. 416. — Ichthyornis victor, a Cretaceous toothed bird of flight,
(Restored by Marsh.)
natural size.
Hesperornis, the anterior parts, especially the wings and keel, were
strongly developed, while the legs and feet were small and slender.
Their biconcave vertebrae and other skeletal features, as well as their
small brains, show primitive reptilian relations. Their habitat was
the same as that of Hesperornis, and yet the two were farther apart
structurally, than any two types of birds now living (Marsh).
Several genera of birds, embracing altogether about 30 species,
THE CRETACEOUS PERIOD. 185
are now known from the Cretaceous; but less than half a dozen of
them belong to the Hesperornis type.
Compared with the Jurassic Archceopteryx, both the Hesperornis
and Ichthyornis show progress in the abbreviation of the long bilater-
ally feathered tail, and in the loss of the distinct fingers and claws;
but, on the other hand, the fish-like vertebra? of Ichthyornis, and the
groove-set teeth of the Hesperornis, are features almost as primitive
and reptilian as any possessed by the Jurassic bird. This illustrates,
as noted by Marsh, that certain parts of an animal may linger in a
primitive condition, while other parts make notable advances. The
wide divergence of the two Cretaceous types from one another, and
the divergence of both from the Jurassic form, seem to imply that
birds had their origin at a much earlier date. What was happening
in all this time among the true land birds is almost wholly unknown.
The seaward movement. — From the foregoing, it will be seen that
a notable feature of the period was the marked movement of land forms
to the sea. Besides the ichthyosaurs and plesiosaurs, whose ancestors
were land forms which went down to sea when the Jura-Trias sea
extension reduced the land-area, and broadened the shallow seas,
there were now added, in this greater period of sea extension and land
restriction, the dolichosaurs and pythonomorphs descended from some
land form of the scaled reptiles, the sea turtles from the terrestrial
chelonians, a marine rhynchocephalian from some land form, and aquatic
birds, one form of which was specialized for sea life as perhaps no bird
was before or has been since, besides the further marine adaptation
of the crocodilians and the pterosaurs, one type of which was also
extremely specialized for aquatic life. All this is doubtless but a natu-
ral outcome of the prolonged and extensive transgression of the sea
upon the face of the continents.
The marine fishes. — A very important change took place in the
fish fauna, in the transfer of dominance from the ganoids and other
forms of ancient fish to the teleosts, the present prevailing kind. This
change set in during the Comanchean, much as did the change in the
plants, and was complete by the middle of the Later Cretaceous, thus
running singularly apace with the evolution of the angiosperms. It
is not easy to see any genetic relationship between these changes, for
the teleosts do not seem to be in any notable way dependent on angio-
spermous vegetation. Though modern in type, the special forms were
186 GEOLOGY.
yet in the main ancestral, and are now extinct. The sharks and rays
were chiefly of the modern types, though not of .living species.
The marine invertebrates. — The most notable departure from the
precedents of the preceding ages is the prominent place which the
rhizopods or foraminifers took in the record. They made large con-
tributions to the distinguishing formation of the period, the chalk,
and they were concerned in the formation of the greensand, scarcely
less characteristic of the period than the chalk. While these minute
organisms live on shallow bottoms, on fixed algse, and in abysmal
water, they are chiefly denizens of the surface waters of the open sea.
It is not essential to them that the sea be deep, but in shallow seas the
relatively large amount of terrigenous material deposited, the mechani-
cal action of clastic material, and the prevalence of higher forms of life
that prey upon them, render the accumulation of their shells in dis-
tinctive deposits rare, while in the abysmal waters, where these hostile
agencies are essentially absent, foraminiferal oozes are characteristic
formations. On this account, it was formerly held that the chalk
deposits were of deep-sea origin, and hence implied deep depression
of the chalk-areas; and since shallow- water deposits are sometimes
intercalated between chalk-beds, profound oscillations of level were
freely deduced. But the presence in the chalk of the fossils of shallow-
water life, joined to other considerations, has forced the essential aban-
donment of this view. The relative prominence of the foraminifers
becomes all the more curious on this account. The breadth of the
epicontinental seas, the lowness of much of the land, and its ample
vegetal mantle, sufficiently explain the restriction of clastic com-
petition and the associated destructive action; but they leave the
relative scantiness of the usual invertebrate life of clear and shallow
seas unexplained. Two suggestions of uncertain value may be offered:
(1) the water, though not deep in the abysmal sense, may have been
somewhat too deep over the chalk-areas to furnish congenial condi-
tions for most of the invertebrates, and (2) the limitation of the fresh-
water supplies of food usually borne out by the rivers may have affected,
adversely the food-supply upon which the shallow-water invertebrates
depend.
Sea-urchins were quite abundant, and lent one of its characteristic
aspects to the fauna (Fig. 417, q-u), while corals and crinoids, so long
associated with clear seas, were not abundant, facts which lend some
THE CRETACEOUS PERIOD. 187
support to the first of the above suggestions, since the sea-urchins
have considerable range in depth, and forms not unlike those of the
Cretaceous are now dredged from deep water.
In the clastic formations, the pelecypods and gastropods furnished
a notable and characteristic element (Fig. 417, j-p). It will be seen
by a glance at the figures that they were making progress in moderni-
zation. The cephalopods were still a dominant feature, though the
ammonites were in their decline, and were showing erratic divergen-
cies of form attended by much ornamentation similar to that which
marked corresponding stages of the trilobites and crinoids. Odd
forms of partial uncoiling, or of spiral and other unusual forms of coil-
ing, were striking features. Fig. 417, e and h, illustrate two of these.
The aberrations were not usually systematic, but affected various
genera and species, and even the same individuals differently at different
stages, some being quite symmetrical up to a certain age, and then
becoming erratic; but even this does not hold universally. It lends
some little plausibility, however, to the view that these eccentricities
mark the senility of the race. An interesting form perhaps to be
classed here was the Baculites, which resumed the straight form of
the primitive Orthoceras, while it retained the very complicated suture
of the Ammonites (Fig. 417, g). Typical forms of the ammonoids are
shown in Fig. 417, 6, c, d, and these are to be regarded as repre-
senting the main lines of progress. The belemnites were abundant,
represented particularly by Belemnites and Belemnitella. These also
were near ing the end of their race.
Special faunas. — On the Atlantic coast there were, at the north, a series of
subfaunas corresponding to the Ripley fauna at the south, and above these
(New Jersey and Maryland), there were faunas not found at the south.1
The earliest faunal group at the north embraced the sub-faunas of the
Mer chant ville, Woodbury, Marshalltown, and Wenonah beds, and corre-
sponded essentially with the fauna of the Matawan formation.2 In the Mer-
chant ville sub-fauna, Axinea mortoni, Idonearca antrosa, Trigonia eufaulensis-
and Panopea decisa are abundant. In the Woodbury beds next above, most of
these are rare, and Cyprimeria, Breviarca, Lucina cretacea, Cancellaria subalta>
and others, rare or absent below, become the commonest species. In the Marshall,
town beds, Trigonia, Cyprimeria , and Idonearca vulgaris are abundant, while
1 See Reports of Maryland and New Jersey.
2 Weller and Knapp, The Classification of the Upper Cretaceous Formations and
Faunas of New Jersey, Jour. Geol. XIII, 1905, pp. 71-84.
188
GEOLOGY.
s u p
FIG 417 —CRETACEOUS INVERTEBRATES. (For explanation of figure see p. 189.)
THE CRETACEOUS PERIOD. 189
the ponderous Gryphcea vesicularis and Exogyra ponderosa, with Ostrea larva in
great abundance, are conspicuous faunal elements. In the Wenonah beds,
the uppermost member of the group, there is a return of many of the species
of the earliest subfauna, implying that the fluctuations in life were local.
A more marked faunal change then ensued, corresponding approximately
to the transition from the Matawan to the Monmouth, in which a new immi-
grant element is introduced, characterized by Belemnitella americana and
Terebratella plicata. There is at the same time a recurrence of the big oysters,
Gryphcea vesicularis, Exogyra costata, and Ostrcea larva. Within the Monmouth
formation there are also recurrences of other Matawan species. The above, in a
general way, stand for the faunas of the lower portion of the series, south to
the Mississippi embayment, including the Eutaw and Ripley faunal groups.
At the north, the Rancocas fauna was characterized by the brachiopod
Terebratula harlani, associated with many Gryphcea vesicularis that lived on from
the earlier stages, and, especially in the Vincentown lime sand, by the great
numbers of bryozoans and shells of foraminifera. The uppermost horizon, the
Manasquan, is characterized by Caryatis veta and Crassatelladela warensis.
In the Texan province, the lower divisions contain many species common
to the faunas of the Atlantic coast, implying close relations. The recurrences
of the species above noted are probably but expressions of migrations to and
fro in the Atlantic-Gulf coastal tract, as the local conditions varied. The most
marked departure from the Atlantic faunas was in the chalk formation (Austin
limestone), in which the foraminifers Textularia and Globigerina, and the sea
urchins Hemiaster and Cassidulus, were important features. The Inoceramus
and the ammonites also played a much more conspicuous part, and the fauna
was otherwise related to that of the great interior sea.
EXPLANATION OF FIG. 417. — CEPHALOPODA, a, Nautilus meekanus Whitf., one of the
simplest types of closely coiled cephalopods. Note the smooth shell and the simple
sutures; b, c, Prionotropis woolgari (Mantell), a normal ammonite, with highly
ornamented shell and moderately complex sutures; d, Scaphites nodosus Owen, an
ammonite exhibiting a slight tendency to uncoil in the last volution; e, /, Helicoceras
stevensoni Whitf., an ammonite coiled in a heliciform spiral, with its highly compli-
cated suture; g, Baculites grandis M. and H., a straightened-out ammonite, with
a moderately complex suture. In its infantile stage, this form starts as a closely
coiled shell; h, i, Ptychoceras crassum Whitf., an ammonite which, in the stage
shown in the figure, is no longer coiled but recurves upon itself. PELECYPODA:
/, Inoceramus vanuxemi M. and H., a representative of one of the most character-
istic genera of Cretaceous shells; k, Ostrea soleniscus Meek, a representative of a
genus which with its near allies reached its greatest development in the Creta-
ceous period; I, Idonearca nebrascensis Owen, a shell allied to the areas of the
recent seas. GASTROPODA: m, Pyropsis bairdi (M. and H.), n, Drepanochilus
nebrascensis (E. and S.), o, Aphorrhais prolabiata (White), p, Neptunella inter-
textus (M. and H.). The canaliculate and modified apertures of these shells
differentiate them sharply from the ancient Paleozoic types of gastropods, and sug-
gest some of the shells of recent seas (Compare with Tertiary Figs.). ECHINOIDEA:
q, r, Salenia tumidula Clark; s, Pedinopsis pondi Clark, two forms of regular sea
urchins in which the only lack of radial symmetry is in the apical system of plates,
as is well shown in g; t, Botriopygus alabamensis Clark; u, Cassidulus subquadratus
Con., two sea-urchins in which the bilateral symmetry is strongly developed.
(Weller.)
190 GEOLOGY.
In the interior sea, the ammonoids, the nautiloids, Inoceramus, and the
oysters were conspicuous forms. The gastropod element was prominent in
the Fox Hill stage, and the foraminifers in the chalk deposits. In the Colorado
series, Inoceramus and several genera of ammonites constitute the most con-
spicuous element in the fauna, associated however with many forms of pelecy-
pods and gastropods. In the Montana series the faunas much more closely
resemble those of the Atlantic border province, a considerable number of
identical or closely allied species being common to these faunas and those of
New Jersey.
In the Pacific-coast province, the (Upper) Cretaceous faunas are less exten-
sive than those of Comanchean age, but the Cretaceous faunas, like the Coman-
chean, are quite distinct from the contemporaneous faunas which lived in the
more easterly provinces. They include several ammonites of types quite differ-
ent from those of the interior and the east, besides various genera and species
of pelecypods and gastropods.
NOTE. — From a paper which came to hand after this chapter was in type, it
appears that certain beds of Colorado, New Mexico, and Oklahoma, which have
usually been regarded as a part of the Dakota formation, are really Comanchean,
and of marine origin.1
1 Stanton Jour, of Geol., Vol. XIII.
CHAPTER XVI.
THE EOCENE PERIOD.
The Cenozoic Era. — The remaining periods of geological history con-
stitute the Cenozoic era, the era of modern life. The era is commonly
divided into two principal parts, the Tertiary and the Quaternary.
These principal divisions are variously subdivided, as shown below:
f Recent, or Human. Post-glacial formations.
Quaternary \ Pleistocene, or Glacial. Glacial formations and non-glacial
deposits of glacial age.
f Pliocene Pliocene
Neocene.
Tertiary "ȣ" Miocene
[ Eocene Eocene Eocene.
The threefold subdivision of the Tertiary is the one which seems
to best fit the phenomena of our continent as now understood, though
there is a growing tendency toward the recognition of the Oligocene.
This tendency seems to mean that beds are found in our continent
which carry fossils similar to those of the Oligocene of Europe, rather
than that the Oligocene of this continent constitutes a natural and
major subdivision of the Tertiary.
The nominal basis of the Cenozoic classification and nomenclature is a radi-
cal departure from that used for earlier eras. Here, stages of approach to exist-
ing types of life are made the basis, at least nominally. Originally, Eocene
(dawn of the recent) formations were defined by the presence of a few fossils
of living species, specifically 3^ per cent, generalized to 5 per cent or less; Mio-
cene (less recent, i.e. less than half the fossils represent living species), defined
by about 17 per cent, generalized to mean a minority, of living species; and Pli-
ocene (more recent) by 36 to 95 per cent, interpreted as a majority.
On its face, this classification seems as artificial as the Linnsean classification
of plants by the number of their stamens, though it has a somewhat more natu-
191
192 GEOLOGY.
ral origin. Certain formations in the London and Paris basins were taken as
the type of the Eocene, and they contained 3£ per cent of living species, as then
determined. Certain other formations in southern • France, containing 17 per
cent of recent species, as then determined, were taken as the type oi the Miocene,
and others in Italy of much larger and varying percentages, as the type of the
Pliocene. Dana1 generalizes the criteria as follows: Eocene, no species, or
less than 5 per cent living; Miocene, 20 to 40 per cent living; Pliocene, more
than half the species living.
It is not surprising that it was soon found that this scheme did not
fit the facts in Germany, and an additional division, Oligocene (few recent),
was introduced between Eocene and Miocene, taking something from
each. In practice, the criteria have not been closely adhered to, and
movement toward a natural system has been in progress; but common con-
sensus of opinion as to what constitutes the true basis of a natural system has
not yet been reached, and the movement is not very definitely directed. There
are geologists who do not believe that there are natural divisions of general appli-
cability, the divisions that are natural for one region being unnatural for other
regions. With the qualification that all views must yet be put to the test when
the whole world shall have been carefully worked over, and that views now
expressed must not be held as authoritative, or even necessarily representative,
it is proper that we state our convictions, and their application to the unsettled
questions of Cenozoic classification and nomenclature.
We believe that there is a natural basis of time-division, that it is recorded
dynamically in the profounder changes of the earth's history, and that its
basis is world-wide in its applicability. It is expressed in interruptions
of the course of the earth's history. It can hardly take account of all local details,
and cannot be applied with minuteness to all localities, since geological history
is necessarily continuous. But even a continuous history has its times and
seasons, and the pulsations of history are the natural basis for its divisions.
In our view, the fundamental basis for geologic time divisions has its seat
in the heart of the earth. Whenever the accumulated stresses within the body
of the earth over-match its effective rigidity, a readjustment takes place.
The deformative movements begin, for reasons previously set forth, with a
depression of the bottoms of the oceanic basins, by which their capacity
is increased. The epicontinental waters are correspondingly withdrawn into
them. The effect of this is practically universal, and all continents are
affected in a similar way and simultaneously. This is the reason why the
classification of one continent is also applicable, in its larger features, to
another, though the configuration of each individual continent modifies the
result of the change, so far as that continent is concerned. The far-reaching
effects of such a withdrawal of the sea have been indicated repeatedly in the
preceding pages. Foremost among these effects is the profound influence exerted
on the evolution of the shallow-water marine life, the most constant and reliable
1 Manual, 4th ed., p. 880.
THE EOCENE PERIOD. 193
of the means of intercontinetal correlation. Second only to this in importance
is the influence on terrestrial life through the connections and disconnections
that control migration. Springing from the same deformative movements are
geographic and topographic changes, affecting not only the land, but also the
sea currents. These changes affect the climate directly, and by accelerating
or retarding the chemical reactions between the atmosphere, hydrosphere, and
lithosphere, affect the constitution of both air and sea, and thus indirectly influ-
ence the environment of life, and through it, its evolution. In these deformative
movements, therefore, there seems to us to be a universal, simultaneous, and fun-
damental basis for the subdivision of the earth's history. It is all the more
effective and applicable, because it controls the progress of life, which furnishes
the most available criteria for its application in detail to the varied rock forma-
tions in all quarters of the globe.
The main outstanding question relative to this classification is whether
the great deformative movements are periodic rather than continuous, and
cooperative rather than compensatory. This can only be settled by compre-
hensive investigation the world over; but the rapidly accumulating evidence
of great base-leveling periods, which require essential freedom from serious
body deformation as a necessary condition, has a trenchant bearing on
this question. So do the more familiar evidences of great sea transgressions,
which may best be interpreted as the consequence of general base-leveling
and concurrent sea-filling, abetted by continental creep during a long stage
of body quiescence. It is too early to affirm, dogmatically, the dominance in
the history of the earth of great deformative movements, separated by long
intervals of essential quiet, attended by (1) base-leveling, (2) sea-filling, (3) con-
tinental creep, and (4) sea transgression; but it requires little pro*
phetic vision to see a probable demonstration of it in the near future. Sub-
ordinate to these grander features of historical progress, there are innumerable
minor ones, some of which appear to be rhythmical and systematic, and some
irregular and irreducible to order. These give rise to the local epochs and epi-
sodes of earth-history, for which strict intercontinental correlation cannot be
hoped, and which must be neglected in the general history as but the individuali-
ties of the various provinces.
The periods which have been recognized in the Paleozoic and Mesozoic,
chiefly on the basis of European and American phenomena, seem to us likely
to stand for the whole world, with such emendations as shall come with widening
knowledge.
The classification of the Cenozoic is more hampered by the artificiality of
its names, by the intricacy of its details, and by the (as yet) imperfect appli-
cation of the newer modes of investigating and interpreting the phenomena of
the geology of the land, as distinguished from the older branch, the geology of the
sea. A large part of the known deposits of the Tertiary are non-marine. They
have been interpreted as lacustrine, and the areas of their deposition as lake
basins. The Tertiary has even been called the age of lakes. Certain topo-
graphic interpretations are necessary to provide the requisite basins, and this
194 GEOLOGY.
has hampered the whole physiographic conception of the period. It is prob-
able that this conception must be largely abandoned, and the broader view
of land aggradation, with lacustrine deposits as an incident, substituted,1
and with this change will come some emendation of topographic and dynamic
interpretations.
In applying a classification based on body deformation, some regard must
be had to the fact that while sea-withdrawal, as the result of increased capacity
of the sea-basins, is simultaneous the world over, continental deformations and
crustal foldings are more local and less nearly synchronous, for there is no agency
to combine and equalize their effects as in the case of the basins. Continental
deformations must be employed in the classification with some latitude, and
correlations based on them cannot be expected to have an equally high order
of exactness. Local advances and retreats of the sea due to local warpings
must be eliminated or neglected, in a general classification, for the reason that
they are local. If an attempt were made to shift the classification of the Tertiary
period to the basis here outlined, the changes would not be radical.
After the deformative movements that closed the Mesozoic era, there seems
to have followed a rather protracted period of relative quiescence. In the early
part of this period, the area of the land was large, and its relief pronounced.
Secondary movements of adjustment through minor warpings, creep, and grada-
tion were in notable progress. During the later portion of the period, the
effects of these adjustments were felt in some notable extension of the sea over
the lower portions of the continental platforms. For North America this
transgression of the sea is represented in Fig. 418. The most notable feature
was the extension of the sea in the Mississippi embayment, represented by
the formations to be described later. This advance of the sea did not rival
the great transgressions of the Cretaceous and Jurassic periods, but the Atlantic
and Pacific seem to have joined between the two Americas, and the climatic
effects of a dominantly marine period seem to have prevailed, as indicated by
the warm-temperate life in middle and high latitudes. All of this seems to
constitute a natural period, embracing what is included in the Eocene and the
Lower Oligocene (Vicksburgian).
In North America, this period was closed by a withdrawal of the sea from
both the Atlantic and Pacific borders of the continent, and by notable crustal
deformations in some parts of the western mountain region. At the same time,
Florida, which had been submerged and the site of calcareous sedimentation,
was partly emerged. Farther south, the changes were even more important,
for they appear to have interrupted the connection between the Atlantic and
1 See Davis, Science, N. S., Vol. VI, p. 619, 1897, and Proc. Am. Acad. Arts and
Sci., Vol. XXXV, p. 345, 1900; and Mus. Comp. Zool.-Geol. Surv., Vol. VI, pp. 43, 45-7,
and 48; Gilbert, Pueblo folio, U. S. Geol. Surv., 1897, and Nat. Geog. Mag. Vol. IX, pp.
308-317, 1898; Matthew, Am. Nat., Vol. XXXIII, p. 403, 1899; Hatcher, Proc. Am.
Phil. Soc., Vol. XLI, 1902, Rev. Jour, of Geol., Vol. XI, p. 92, and Johnson, W. D.,
21st Ann. Kept. U. S. Geol. Surv., Ft. IV.
THE EOCENE PERIOD. 195
the Pacific in tropical latitudes, diverting the equatorial current of the Atlantic
to the northern part of that ocean. These changes, with their attendant effects
on climate, influenced the character and distribution of the life. The initial
bowing of the Pyrenees and some other mountains in southern Europe is assigned
to this time. It is therefore tentatively assumed that there was a sufficiently
general deformative movement at the close of the Eocene to mark the end of a
a natural period.
The time occupied in these movements and in the secondary results which
immediately followed may be regarded as a transitional stage, and referred to-
the Oligocene, with the rank of an epoch rather than a period. In the lower
Mississippi region, the deposition of this epoch took on a terrestrial and a marine
phase, the terrestrial recorded by a part of the Grand Gulf beds, containing,
land plants with occasional fresh-water molluscs; the marine by the Chatta-
hoochie formation. Inland, the White River beds of the Great plains are referred
to the same epoch. Matthew * urges that these are of eolian origin, practically
an ancient loess, which, if true, implies something of aridity in the west, a con-
dition in harmony with the rapid evolution of the solid-hoofed animals adapted
to dry plains, with the gypseous deposits in the Grand Gulf series, and with the
notable gypsum formations of the Paris basin, referred to the Oligocene. In
these are seen the natural consequences of an epoch of land extension.
The true Miocene, according to Dall,2 was ushered in by a marked change
in the temperature of the waters of the Atlantic coast, attributed to a northern
current, and resulting in the sharpest faunal change in the Tertiary series of
the Atlantic coast. Apparently this must mean more than a mere shifting of
preexisting currents, for a cold current so far south can hardly be referred to-
North Atlantic waters, when magnolias and many other trees now confined to
the warm temperate zone were growing in Greenland and the Arctic regions
generally. Heer has identified a large flora of forms that now imply a tem-
perate climate, in latitudes of 60° to 80°, which he refers to the Miocene.3 The
correctness of this reference is questioned on other grounds, and the cold Mio-
cene current on the southern coast of the United States, colder than that of
to-day, makes such a reference highly improbable. The Miocene cold current
seems to imply an important climatic change affecting the north Atlantic, and
adds strength to the evidences above cited of the deformative action closing the
Eocene. The flora of Europe referred to the early Miocene is not in harmony
with this supposed cooler condition, since it embraces forms now representative
of warm latitudes; but during the period a marked change in the direction of
the existing flora took place.
During the Miocene, the sea again advanced upon the land on both the Atlantic
and Pacific coasts, though not greatly beyond the present limits, and chiefly
in the Maryland-California latitudes; hence this may be regarded as an inter-
deformative stage, and as extending to the next general deformative movement.
1 Am. Nat., Vol. XXXIII, p. 403, 1899.
2 18th Ann. Rept. U. S. Geol. Surv., 1898, p. 329; see also other papers postea.
8 Flora Fossilis Arctica, Vol. I, pp. 161-166.
196 GEOLOGY.
The next deformative movement was one of the greatest in post-Cambrian
history, and appears to have involved some movement of nearly every mountain
range whose history is known, as well as a very marked withdrawal of the sea,
as indicated by buried or submerged erosion channels traversing the continental
shelves. These are not however regarded as indicating an elevation of the con-
tinent equal to their depth below the present sea-level, but chiefly as indicating flexures
of the continental border attending the deformative movement; even thus
interpreted they imply sea-withdrawal. This great deformation is held to give
a better definition to the Pliocene period than any assigned percentage of living
and extinct shells in the sediments of the time. The extinction of species during
this period seems to have been greatly lessened by reason of the extinctions
and adaptations which had already been brought about by the Oligocene move-
ments and the Miocene cold currents; hence the importance of these changes
is not fully revealed in the immediate faunal change. Their biological influence
can only be fully measured when the secondary effects, through climatic and
other means, have worked themselves out, and this will require a long period,
a part of which is still in the future.
An immediate secondary effect is probably found in the glacial invasions
which, because of their great influence in the history of the land, have been
regarded as constituting a period by themselves, the Pleistocene. In a strict
deformative classification, however, this should be united with the Pliocene,
for important movements seem to have been in progress during the glacial period,
and perhaps the same may be said of the present.
It should perhaps be repeated that this deformative, dynamic classification
is not in accord, in all its details, with the classification by species percentage,
even in its modified form; but there is no serious discrepancy between them,
and if the dynamical considerations shall be supported by future extensions
of knowledge in the less known regions of the earth, the existing rather arbi-
trary classification may easily merge into the dynamical one.
FORMATIONS AND PHYSICAL HISTORY OF THE EOCENE.*
The formations of the Eocene system are found in widely sepa-
rated parts of the North American continent (Fig: 418), but they do
not appear at the surface over extensive areas. Within the conti-
nental area, their extent was not great at the outset, and in many
places they are concealed by younger beds. They include (1) beds
laid down in the sea or below sea-level, and (2) beds deposited on
the land. The former include formations of (a) marine, and (6) .brack-
1 For review of all the literature of the Eocene of the continent up to 1891, see
Clark, Bull. 83, U. S. Geol. Surv. For later publications, see Bulls. 130, 135, 146,
153, 156, 162, 172 and 177. See also article by Ball in 18th Ann., U. S. Geol. Surv.,
Pt. II, where bibliography up to 1898, is given.
THE EOCENE PERIOD.
197
FIG. 418. — Map showing the distribution of the Eocene formations in North America.
The conventions are the same as in former maps.
198 GEOLOGY.
ish-water origin, and the latter those of (a) lacustrine, and (6) sub-
aerial origin (fluvial, pluvial, eolian). The last are probably more
important than has commonly been recognized.
The marine Eocene beds are confined to the borders of the con-
tinent; the brackish- water formations are known in Washington and
Oregon, while the lacustrine and subaerial deposits are found in many
places in the mountains of the west, and on the plains adjacent to
them.
The Eocene formations are like the Cretaceous in that they are,
in most parts of the continent, largely unindurated. Many of them
are still in the condition of sand, gravel, clay, etc., much as when
deposited. Locally, they have been indurated, and still more locally,
metamorphosed.
The Eastern Coast.
The Atlantic coast. — The Eocene formations of the Atlantic and
Gulf coasts appear at the surface at intervals along a belt of varying
width from New Jersey to Texas. The beds dip toward the coast
(Fig. 380), and from the areas where they appear at the surface, they
are continued seaward beneath younger beds.
In the Atlantic Coastal plain, the Eocene beds are separated from
the underlying Cretaceous, by an unconformity. They represent the
incursion of the sea over at least a narrow area from which it had with-
drawn at the close of the Mesozoic. The materials of the Eocene
appear to have been derived largely from the Cretaceous, but sedi-
ments from farther inland were contributed by the drainage from
the highlands and mountains to the west. Clays, sands, and green-
sand (glauconitic) marls are the most common materials of the Eocene
of this province, and the conditions of sedimentation appear to have
been much the same as during the Cretaceous.
, Until recently, attempts to correlate the Eocene sections of the
different parts of the Atlantic and Gulf coasts were not altogether
successful, and it is still common to speak of the Lower, Middle, and
Upper portions of the system in a rather general way.
In New Jersey (Shark River marl) l and Maryland 2 (Aquia and
1 Ann. Rept. State Geologist of New Jersey for 1893 and earlier years.
2 Clark and Martin, Maryland Geol. Surv., Volume on the Eocene. The Eocene
of this region is sometimes called the Pamunkey series.
THE EOCENE PERIOD. 199
Nanjemoy formations), the Lower Eocene only is represented in the
exposed beds referred to this period. In Virginia, the Middle Eocene
is also present, and in the Carolinas, the system is still more complete
(Buhrstone, Santee, Cooper, the last sometimes classed as Oligocene),
though the oldest Eocene beds are thought to be wanting. In Florida,
the Upper Eocene only is exposed. The interpretation of these varia-
tions will be readily made.
The Gulf border. — The Eocene system is more fully represented
in the Gulf region than along the Atlantic coast, and the Lower, Middle,
and Upper divisions are more clearly defined. Their aggregate thick-
ness is not less than 1700 feet (maximum), of which something like half
belongs to the Lower Eocene, and more than half of the remainder
to the Middle.
The section in Alabama, which may be taken as fairly typical of
the Gulf Eocene, is as follows:1
Upper Eocene White limestone (Jackson and Vicksburg, the latter
sometimes classed as Oligocene) 350 feet.
Middle Eocene. . . .The Claiborne series:
Claiborne formation, mainly clays and sands,
calcareous and glauconitic 140 ' '
Buhrstone formation, mainly sand with some
glauconite 300 ' '
Lower Eocene The Lignitic formation, mainly sands and lignite
(Chickasaw) 900 " ±
The Clayton (or Midway) formation, mainly
limestone 10-200 "
It is on the basis of the Eocene of this region that the following
classification has been suggested for the Eocene of the east:2
a) Jacksonian Upper.
) Claibornian Middle.
fc
(c) Chickasawan .} r
(d) Midwayan ) Lower-
The relations of the Eocene strata to the Cretaceous3 are much
the same in the eastern Gulf States as on the Atlantic coast. They
outcrop in a belt just south of that where the Cretaceous beds appear,
1 Smith, Geol. Survey of Alabama, 1894.
2Dall, 18th Ann. Kept. U. S. Geol. Surv., Pt. II. This classification places the
Vicksburg in the Oligocene, instead of associating it with the Jacksonian. There
appears to be no physical reason for this separation.
3 Smith. Geol. Surv. of Alabama 1894.
200 GEOLOGY.
and dip seaward, disappearing beneath younger formations. As along
the Atlantic coast, the Eocene sediments seem- to have been derived
largely from the Cretaceous; but this is not true of all parts of the sys-
tem, for about the lower Mississippi, much of the Lower Eocene is
lignitic, while the Upper Eocene (in Mississippi and Alabama) is com-
posed largely of limestone. A great bay or estuary appears to have
occupied the site of the lower part of the Mississippi as far north as
the mouth of the Ohio, and in this embayment the deposits extend
much farther north than elsewhere. The Lower Eocene (Lignitic
formation) extends farther north than the later beds.
Western Gulf region. — The Texas Eocene,1 which sometimes appears
to be conformable with the Cretaceous, is composed chiefly of shallow-
water marine deposits; but lignite, and gypsiferous and saliferous
sediments recur at various horizons, showing the recurrence of ter-
restrial and non-marine conditions within the general area of depo-
sition. Iron ore and silicified wood are of common occurrence in con-
nection with the lignite. There are numerous local unconformities in
the system, suggesting recurrent changes in the conditions and areas
of sedimentation. The Lower and Middle series are represented, and
probably the Upper, though there is difference of opinion as to the
upper limit of the system in this region.2 The system attains a thick-
ness of several hundred (800 at least) feet. Various names are applied
to different parts of the system in different parts of the State. The
fossils are such as to suggest that shallow-water marine life was able to
find its way from the Gulf to the Pacific, and vice versa, during this
period.
The Eocene of Texas and Louisiana is continued northward into
Arkansas, where the Lower and Middle divisions, and perhaps the
Upper, are found.3
The Pacific Coast.
The changes which marked the close of the Mesozoic era resulted
in the exclusion of the sea from most of that part of the present land
1 Bumble, Jour, of Geol., Vol. II. See also Reports of the Texas Geological Sur-
vey, and the Austin and Uvalde folios, U. S. Geol. Surv.
2 Texas Geol. Surv.; Hayes and Kennedy. Bull. 212, U. S. Geol. Surv., pp. 22,
23; Smith and Aldrich. Science, New Series, Vol. 16, pp. 836-9, and Vol. 18, p. 26;
Dall, Science, Vol. 16, p. 946 and 18th Ann. Kept., Pt. II, U. S. Geol. Surv.
3 Harris, Arkansas Geol. Surv., Vol. II, 1892.
THE EOCENE PERIOD. 201
area which had been submerged in the Cretaceous period. This is
shown by the wide-spread unconformity between the Eocene and the
Cretaceous systems. During the interval of emergence, great thick-
nesses of sedimentary rocks were removed, and when the sea again
advanced upon the land in the Eocene period, sediments were laid
down on an eroded surface, which in some places had been reduced
toward planeness by subaerial denudation.
Marine formations are wide -spread in California west of the Sierra
and south of the Klamath mountains, and in Oregon north of the
Klamath mountains and west of the Cascades, but they have little
development within the land-area farther north. Various names have
been applied to the system and to its parts in different localities.
Marine beds. — The Eocene beds of central California are known
as the Tejon series, though other names (e.g. Martinez ) have been
applied to various parts. The Tejon series is best known in the south-
ern part of the great valley of California, then occupied by the sea,
and is well exposed on the east side of the Coast range. It does not
appear in the Sierras, or in the northern part of the central valley.
In some places the Tejon series lies on the Chico with apparent con-
formity, though unconformity is more common. Even where there
appears to be conformity, the bottom of the Tejon is thought not to repre-
sent the oldest Eocene. In the middle part of the Coast range of Cali-
fornia, where the Tejon series is more than 4000 feet thick,1 it is over-
lain conformably by the Miocene. The Tejon series is mainly clastic,
but locally contains lignite, and still more locally, oil.2 In the Santa
Cruz mountains, Eocene beds constitute a part of the metamorphic
Pascadero series.3 In some parts of southern California, the thick-
ness of the Eocene (Escondido series4) is estimated at more than 7000
feet, the material being partly sedimentary and partly igneous. A
bed of gypsum, thick enough to be of commercial value, is found in
this series, and points to the absence of true marine conditions, at
least locally and temporarily. Eocene beds are absent from much of
northern California and southern Oregon.5
1 Lawson, Science, Vol. XV, 1902, p. 416.
2 Eldridge, Bull. 213, U. S. Geol. Surv., p. 306.
3 Ashley, Jour, of Geol., Vol. Ill, p. 434.
4Hershey, Am. Geol., Vol. XXIX, pp. 349-72.
5 Diller, Bull. Geol. Soc. Am., Vol. IV, p. 220.
202
GEOLOGY.
Marine Eocene beds (Arago), resting unconformably on the Cre-
taceous, are wide-spread in western Oregon. They attain great thick-
ness (said to be 10,000 feet x), and make up the mass of the Coast
FIG. 419. — Section showing the structure of the Eocene in western Oregon. Eb,
Eocene basalt; Ep (Pulaski formation), and EC (Coaledo formation), Eocene.
Length of section about 20 miles. (Diller, Coos Bay, Ore. folio, U. S. Geol. Surv.)
range of that State.2 The sediments which compose them appear to
have come from the Klamath mountains. Various beds of marine
Eocene in Oregon, not definitely correlated, have, as in California,
received local names (Umpqua, Tyee,3 Pulaski,4 etc.). The structure
of the Eocene at certain points in Oregon is shown by Figs. 419 and
and 420.
FIG. 420.^-Section a little south of the last, showing the relation of the Eocene (Ep,
Pulaski formation) to the Cretaceous (Km, Myrtle formation), as, amphibolite
schist, and Ps, Quaternary marine sand. (Coos Bay folio, U. S. Geol. Surv.)
Brackish-water beds. — By the beginning of the Eocene, the Puget
Sound depression, possibly to be correlated with the great valley of
California and the Gulf of California, had begun to show itself.5 The
Olympic and Cascade mountain regions on either side of the sound
were high, but not mountainous land; and the region of the sound
was a great estuary, in and about which deposition was in progress.
The sediments accumulated in part at least in brackish water, and
resulted in the thick (estimated at 10,000 to 20,000 feet) coal-bear-
ing Puget formation or series of Washington, the upper part of which
may be Oligocene or even Miocene.6 The conditions of sedimentation
varied considerably during the deposition of this series, as the numer-
ous coal seams show. Of the coal-beds, 125 are said to be thick
1 Diller, Coos Bay, Ore., folio, U. S. Geol. Surv.
2 Roseburg, Ore., folio, U. S. Geol. Surv.
3 Diller, Roseburg, Ore., folio, U. S. Geol. Surv.
4 Diller, Coos Bay, Ore., folio, U. S. Geol. Surv.
6 Willis, Tacoma Folio, U. S. Geol. Surv.
6 Willis, Bull. Geol. Soc. Am. Vol. IX, 1897-8. See also 18th Ann. Rept. U. S.
Geol. Surv. Also Landes, Washington Geol. Surv., Vol. II, p. 170.
THE EOCENE PERIOD. 203
enough to attract prospectors. They range from one to sixty feet
in thickness. Most of the workable coal is in the lowest 3000 feet
of the series. The Eocene period in this region seems to have been
one of interrupted submergence. The area of deposition extended
south into western Oregon, and as far east as the Cascade mountains.
In the Coos Bay region of Oregon, the Ccaledo formation (Fig. 419),
like the Puget formation farther north, contains workable beds of coal
and many beds containing brackish-water fossils.1
FIG. 421. — Map showing the position of known coal-bearing formations in Alaska.
The coal of the Yukon basin is partly Cretaceous and partly Tertiary; that
of southeastern and southwestern Alaska, chiefly Eocene, that of the north-
west coast, Mesozoic. South of Cape Lisburne there are outcrops of Paleozoic
coal-bearing formations. There is also much lignite of post-Eocene age. (Brooks,
U. S. Geol. Surv.)
North of Washington. — British Columbia appears to have been
land during the Eocene period, and the erosion there in progress resulted,
by the end of the period, in a peneplain which has since been elevated
2000 to 3000 feet.2 Eocene beds, much disturbed, have been recog-
nized in Alaska,3 where they are sometimes coal-bearing.
1 Diller, Coos Bay, Ore., Folio, U. S. Geol. Surv.
2Dawson, Science, Vol. XIII, 1901, p. 401. Also Spencer, A. C., Bull. Geol. Soc.
of Am., Vol. XIV, p. 131.
3Dall, Tertiary Fauna of Florida, Trans. Wagner Free Inst., Vol. Ill, Pt. VI,
1903, p. 1548.
204 GEOLOGY.
Terrestrial Formations.
The great warpings and faul tings, and the extensive intrusions
and extrusions of lava which marked the close of the Mesozoic era
in the western part of North America, appear to have developed lands
which were relatively high, in association with tracts which were rela-
tively low. The mountain folds, the fault scarps, and the volcanic
piles seem to have afforded the elevations necessary for rapid erosion,
while the associated valleys and basins and plains furnished lodg-
ment areas for such sediments as the streams, descending from the
steep slopes above, were unable to carry across tracts of low gradient.
Sedimentation on the land was therefore a feature of the Eocene period,
as it has been of all subsequent time. Among the accessible forma-
tions of this and all later periods, those of terrestrial origin are far
more widespread than those of marine origin.
The terrestrial sedimentation of the Eocene period was probably
comparable to that of the present time, though the western mountains
had not then attained their present height. Then as now, temporary
and permanent streams were doubtless aggrading their valleys,
and building fans and alluvial plains where the appropriate condi-
tions were found, while sheet-floods spread debris washed down from
the higher lands on the tracts below. The deformative movements
which initiated the modern era probably gave rise to basins here and
there, in which lakes were formed, and the flows of lava from the unnum-
bered vents of the time doubtless sometimes obstructed valleys, pond-
ing the streams and giving rise to lakes. Under these conditions,
it is probable that much of the debris which was started seaward by
the swift waters of the higher lands found lodgment long before it
reached the sea, some of it at the bases of steep slopes, some of it on
river plains, and some of it in lakes. The wind also made its con-
tribution. The result was an inextricable combination of fluvial,
pluvial, eolian, and lacustral deposits.
Terrestrial formations of Eocene age and of fluvial, pluvial, lacus-
tral, and eolian origin are widespread throughout the western interior,
occurring even in proximity to the western coast. Many of them
'are of limited extent, while others are spread over great areas. Since
the -changes which gave rise to the conditions favoring aggradation
on the land continued, at least intermittently, during the period, the
THE EOCENE PERIOD. 205
principal sources of sediment and the sites of its lodgment shifted
somewhat from time to time, and among the scattered deposits referred
to this period, there are notable differences of age. Several more or
less distinct stages of deposition have been recognized, the distinctions
being based partly on the superposition of the beds, and partly on
the fossils which they contain.1 These several stages are not readily
correlated with those of the coastal regions, since synchrony is not
readily established between formations containing marine fossils on
the one hand, and those containing terrestrial fossils on the other.
1. The oldest recognized stage of the Eocene in the western interior
is the Fort Union (perhaps corresponding to the Midwayan, p. 199).
During this stage, there was an extensive area of aggradation in parts
of North Dakota2 and Montana, and a still larger area in Canada,
where the sediments which constitute the Fort Union beds were
deposited. These beds, composed of sand, clay, etc., are said to be
locally 2000 feet or more thick, and have usually been described as
lacustrine. The presence of fresh- water shells (unios, etc.), is consist-
ent with this conclusion for some parts of the formation; but the
abundance of the leaves at many places is quite as suggestive of sub-
aerial aggradation for other parts.3
The Fort Union beds overlie the Livingston formation (p. 159)
conformably,4 and have been thought, on the basis of their fossils,
to represent the oldest Eocene formations of the interior. It will
be remembered however that the youngest formations referred to
under the Laramie (Arapahoe, Denver, Livingston, etc., p. 158), were
deposited in fresh water or brackish lakes, or on land, and that their
reference to the Laramie instead of the Eocene, is of doubtful pro-
priety. At any rate, the time of terrestrial aggradation, so character-
istic of the Cenozoic era in the western part of North America, had
1 For an account of the deposits near the 40th parallel, see King's Report, Vol. Ir
already cited. For the latest attempt at correlating the several lake formations,
see Ball, 18th Ann. Kept., U. S. Geol. Surv., Pt. II. See also J. H. Smith, Jour.
Geol., Vol. VIII, pp. 444-471.
2 Wilder has recently called into question the separability of the Fort Union and the
Laramie, in western North Dakota. Jour, of Geol., Vol. XII, p. 290.
3 For criteria for distinguishing lacustrine and subaerial formations, see Davis,
Science, N. S., Vol. VI, p. 619, 1897, and Proc. Am. Acad. Arts and Sci., Vol. XXXV,
p. 345, 1900.
4 Little Belt Mountain, Mont., Folio, U. S. Geol. Surv.
206
GEOLOGY.
Nussbaum (Neocene)
Cuchara \
I
Poison Canyon •
Laramie
Trinidad
Pierre shale «
Apishapa -I
Timpus J
Carlisle j
Greenhorn
Graneros {
Dakota j
Morrison (Co- f
manchean (?)) 4
Badito (Carbo- \
niferous (?)) \
Schist and
granite
;.
FIG. 422. — Column
or section of the
formations at the
east foot of the
Rocky Mountains,
Colo. (Hills, U.
S. Geol. Surv.)
THE EOCENE PERIOD. 207
begun by the time the Arapahoe and Livingston formations were
deposited.
To the Early Eocene, the Telluride (or San Miguel1) and Poison
Canyon2 formations (Fig. 422) of Colorado are commonly assigned,
although their equivalence to the Arapahoe of the Denver basin has
been suggested. Locally, the Cretaceous had suffered as much as
7000 feet of erosion subsequent to the post-Laramie uplift before
the deposition of the Telluride formation; 3 but great as this is, it does
not exceed the post-Laramie erosion which is thought to have pre-
ceded the deposition of the Arapahoe formation (p. 158). The Tellu-
ride formation is conglomeratic, and has a maximum thickness
of about 1000 feet, while the Poison Canyon formation, of sandstone
and conglomerate, is said to attain a thickness of 2500 feet. The
assignment of these formations to the Eocene is based on stratigraphy,
for neither has yielded distinctive fossils. While both formations
have been described as lacustrine, it is not clear that this is their origin.
It is difficult indeed to conceive of lacustrine conditions which would
permit the accumulation of such thick and extensive beds of conglomerate.
Another early Eocene formation (Puerco), nearly 1000 feet thick,
is found in northeastern New Mexico and the adjacent part of Colo-
rado. Its exact age has been the subject of much difference of opinion,4
perhaps because the upper and lower parts of the formation have yielded
fossils of different ages.
All the formations referred to the Fort Union stage of the Eocene,
as well as the Arapahoe, Denver, Livingston, Ohio, and Ruby forma-
tions, are to be looked upon as representing the transition from the
Mesozoic to the Cenozoic.
The early Eocene sites of deposition were finally shifted. In
so . far as the sedimentation had been in lakes, the basins may have
been filled or warped out of existence, and in so far as the sedimenta-
tion had taken place subaerially, the deformative movements of the
time, or the progress of the gradational work of the streams, or both,
1 Purington, Telluride, Colo., Folio, U. S. Geol Surv. This formation formerly
called San Miguel, is now known as the Telluride. Bull. 182, U. S. Geol. Surv., p. 36.
2 Hills, Science, N. S., Vol. XV, p. 417, 1902, and Spanish Peaks and Walsenburg,
Colo., Folio, U. S. Geol. Surv.
3 21st Ann. Kept. U. S. Geol. Surv., Pt. II, p. 99.
4 Osborn, Bull. Am. Mus. Nat. Hist., Vol. VII, p. 1, 1895. Wortman, Sci., N. S.,
Vol. VII, p. 852, 1897, and Scott, Sci., N. S., Vol. II, p. 499, 1895.
208 GEOLOGY.
may have been responsible for the shifting of the areas of deposi-
tion.
2. At a later stage of the period, as judged by the fossils, aggra-
dation was in progress over much of Utah, western Colorado, and
Wyoming. On the supposition that the sediments were all lacus-
trine, it was formerly suggested that a single great lake, perhaps formed
by the spread and union of several earlier ones, may have reached
from New Mexico on the south to the Wind River mountains on the
north, during this stage of the period, covering a large part of western
Colorado and eastern Utah, and having a length of about 500 miles,
and a maximum width of 300. Even if the formations be partly
subaerial, as their fossils and composition indicate, the preceding
suggestion seems to emphasize the essential continuity of sedimenta-
tion over a great area.
The deposits of this time represent the Wasatch stage l of the Eocene
(perhaps corresponding to the Chickasawan, p. 199). The beds of
this stage have a maximum thickness of 4000 feet near the Wasatch
range, and are now 6000 to 7000 feet above the sea. At about the
same time, as indicated by the fossils, there was an area of sedimen-
tation in the Bighorn basin in northwestern Wyoming. Some defor-
mation of the Wasatch beds followed their deposition.2
The sites of other small areas of deposition believed to be refer-
able to the Wasatch stage are known east of the mountians in south-
ern Colorado 3 (Cuchara formation), and they doubtless occur at other
points as well.
All Eocene formations of Wasatch age or older, are referred to
the Lower Eocene.
3. The third recognized stage of the Eocene of the west is the
Bridger4 (perhaps corresponding to the Claibornian). During this
stage, there were several known areas of sedimentation, lacustrine
1 Here belong the Vermilion group of King, op. cit., the Coryphodon beds of Marsh,
Am. Jour. Sci., Vol. 14, p. 354, 5th Ann. Kept. U. S. Geol. Surv., p. 252, and Mono.
X, U. S. Geol. Surv., p. 6, and the Bitter Creek group of Powell Geol. of the Uinta
Mountains, pp. 64 and 162.
2 King, Geol. Expl. of the 40th ParaUel, Vol. I, p. 754.
3 Walsenburg folio, U. S. Geol. Surv.
4 The Green River group of Hay den, 3d Ann. Kept. U. S. Geol. Surv. of the Terri-
tories, 1869, p. 191, and Powell, Geol. of the Uinta mountains, pp. 63 and 166; and the
Wind River group of Hayden, Am. Nat., 1878, p. 831, and the Dinoceras beds of
Marsh, are here included.
THE EOCENE PERIOD. 209
or subaerial, or both. In the several areas, the sedimentation was
partly contemporaneous and partly successive. One area of depo-
sition was in the Wind River basin, north of the mountains of that
name. Later, deposition was in progress in the basin of the Green
River in Wyoming, and also in the basin of the same river south of
the Uintas. In these areas, beds of sediment, said to be locally as
much as 2500 feet thick, were deposited.1 The materials are chiefly
clastic, though there is not a little calcareous matter in some places.2
It may have been during this stage that the formation of volcanic
tuff (San Juan, 2000 feet and less in thickness) of the Telluride region
was made.3 This formation is of interest as an index to the vigor of
volcanic action in this region. At about the same time, the Huerfano
formation, of Colorado, estimated to have a thickness of 3300 feet,
was laid down. At the close of this stage there was some defor-
mation in southern Colorado, where the beds already deposited were
tilted. In some places (Sangre de Cristo range) mountain-making
was in progress.4
4. The Uinta (perhaps Jacksonian) stage 5 followed the Bridger.
Crustal movements, or the progress of gradation, or the effects of
vulcanism, or all together, seem to have shifted the sites of sedimenta-
tion from the areas where the Bridger beds were deposited, to an area
lying mostly south of the Uinta mountains, in southeastern Utah
and southwestern Colorado. The area of the Uinta deposits occupied
a part of the area covered by the Wasatch and Bridger formations,
and where this was the case, the Wasatch, Bridger, and Uinta beds
are found in superposition. The Uinta beds now have an altitude
of 10,000 feet, though they may have been deposited at a much lower
level.6 At the close of this stage, the new-made deposits were tilted
and somewhat deformed.7
Eocene deposits of lacustrine or subaerial origin are known at numer-
1 King, op. cit.
2 King, op. cit., p. 381.
3 Purington, Telluride, Colo., folio, U. S. Geol. Surv.
4 Hills, Walsenburg folio, U. S. Geol. Surv.
5 Here belong the Diplacodon beds of Marsh and the Browns Park group of Powell;
Geol. of the Uinta Mountains, pp. 63, 168, 208.
6 It is possible that some of these beds should be referred to the Oligocene stage
of the period.
7 King, op. cit., p. 448.
210 GEOLOGY.
ous other points in the western mountain region. In northern Oregon,
there are late Eocene beds of terrestrial origin (Clarno formation)
in the John Day basin, which was the site of aggradation during a
large part of the Tertiary. The Clarno beds are chiefly of volcanic
tuff.1 Eocene beds of similar nature occur in western Oregon, cen-
tral Washington, and northwestern Idaho.2 In Washington, two
thick, sedimentary formations (the Swauk, early Eocene, 3500-5000
feet, below, and the Roslyn, 3500 feet, above) of Eocene age and non-
marine origin, are separated by 300-4000 feet of basalt (Fig. 423).
The Swauk formation (conglomerate, arkose, sandstone, shale, etc.)
is described as lacustrine, while the Roslyn contains much coal.3 The
Payette formation of Idaho, formerly classed as Miocene, is now referred
to the Eocene.4 It is said to have been accumulated in a lake formed
by the damming of the upper basin of the Snake river, by the early
lava-flows of the Columbia river region.5 The Payette beds range
in altitude from 4100 to 6900 feet. If they are all lacustrine, a large
part of this range is due to later deformation.
Eocene beds of terrestrial or volcanic origin are imperfectly known
at other points, as in the Yellowstone Park 6 (Pinyon conglomerate),
in the Absaroka 7 region to the east, in Montana 8 (Sphinx conglomer-
ate), in Arizona 9 (White tail conglomerate, fluviatile), where there
were igneous eruptions and faulting before the end of the period, in
Nevada 10 (Amyzon formation), in Utah (Manti, mainly shale),11 and in
southern California (Mojave formation, sandstone, clay, tuff, and
lava-flows).
The sediments of the Eocene system of the western mountains are
principally clastic, and there is not a little gravel and conglomerate.
Associated with these common sorts of sediment, there is much pyro-
I Merriam, Jour. Geol., Vol. IX, p. 71, and Bull. Univ. of Gal, Vol. II, p. 285,
and Knowlton, Bull. 204, U. S. Geol. Surv.
2Knowlton, op. cit., pp. 110-113.
3 Smith, Geo. Otis, Mount Stuart, Wash., folio, U. S. Geol. Surv.
4 Knowlton, op. cit., p. 110.
5 Lindgren and Drake, Nampa and Silver City, Idaho, folios, U. S. Geol. Surv
9 Weed, Yellowstone Park folio, U. S. Geol. Surv.
7 Hague, Absaroka, Wyo., folio, U. S. Geol. Surv.
8 Peale, Three Forks, Mont., folio, U. S. Geol. Surv.
9 Ransome, Globe and Bisbee folios, U. S. Geol. Surv.
10 King, op. cit., p. 393; and Cope, Am. Nat., Vol. XIII, p. 332, 1879.
II Cope, Am. Nat., Vol. XIV, p. 303, and Vol. XXI, p. 454, 1887.
THE EOCENE PERIOD.
211
02
§ 1 Rhyolite, 100-800
g I feet
Roslyn formation,
3500 feet ±
Teanaway basalt,
300-4000 feet
Swauk sandstone,
3500-5000 feet
FIG. 424.— Section of
the Eocene in the
vicinity of Mt. Stu-
art in the central
part of Washing-
ton. (G. O. Smith,
U. S. Geol. Surv.)
Pre-Tertiary
212 GEOLOGY.
clastic rock and some lava. The beds are for the most part but imper-
fectly indurated, and their erosion has locally given rise to the topog-
raphy characteristic of " Bad Lands."
Subaerial formations of Eocene age have not been certainly iden-
tified far east of the Cordilleran region. It has recently been sug-
gested, though with little probability, that certain preglacial gravels
of Indiana may belong to this system.1
Igneous activity. — The period of igneous activity which was inau-
gurated with the close of the Cretaceous seems to have continued,
at least intermittently, throughout the Eocene, for igneous rocks of
Eocene age are found in California,2 Oregon,3 Washington,4 Idaho,5
Montana,6 Wyoming,7 and Colorado.8 In some places, the exact age of
the igneous rocks associated with Eocene sedimentary beds has not
been determined, but volcanic ash and other forms of fragmental
volcanic matter form a part of the Eocene system at so many points
in the west, and so many lava sheets are associated with the sedi-
mentary beds of the system, that there can be no doubt as to the wide-
spread volcanic activity of the time. Igneous rocks of Eocene age
are also known south of the United States in the Antillean and Cen-
tral American regions.
General considerations. — Judged by the thickness of the beds in
most places, the Eocene period would seem to have been of less dura-
tion than most of the periods which preceded. This, however, is
not a safe criterion for the estimate of time, since it does not take
into account either the discontinuity of sedimentation in any one
place throughout the period, or the rate of sedimentation. Even on
the basis of thickness, however, the showing of the system is by no
means insignificant, as the formations of Puget Sound, Coos Bay, Ore.,
and southern California show. In the western interior, too, the thick-
ness of the beds is often great, especially when it is remembered that
1 Fuller and Clapp, Patoka, Ind.-Ill. folio, U. S. Geol. Surv.
2 Hershey, Am. Geol., Vol. 29, p. 349.
3Diller, Roseburg, Ore., folio, U. S. Geol. Surv.
4 Smith, G. O., Mount Stuart folio, U. S. Geol. Surv.
5Lindgren and Drake, Nampa and Silver City folios, U. S. Geol. Surv.
6 Weed, Fort Benton and Little Belt Mountain folios, U. S. Geol. Surv.
7 Hague, Absaroka folio, and Iddings, Yellowstone folio, U. S. Geol. Surv.
8 Telluride, La Plata, Spanish Peaks, Walsenburg, and Anthracite and Crested
Butte folios, U. S. Geol. Surv.
THE EOCENE PERIOD. 213
the thickness of the system should include the thicknesses of the beds
deposited in the several successive areas of deposition. King esti-
mated the maximum thickness of the Eocene near the 40th parallel at
10,000 feet.1 Furthermore, any just estimate of the duration of the
period must take account of the great erosion after the post-Laramie
deformation, and before the recognized Eocene deposition began, in the
places where the beds are now known, for it is to be remembered that
the Eocene beds are generally unconformable on the Cretaceous. Thus
in western Oregon, the Cretaceous formations had been largely removed,
and the surface well advanced toward base-level after the post-Cre-
taceous deformation, before the incursion of the Eocene sea permitted
marine sedimentation within the present land area. After Eocene
sedimentation began, there was still time before the end of the period
for the deposition of 10,000 feet (as sedimentary beds are measured)
before the close of the period. We must not conclude therefore that
the Eocene period was short, because the system is thin in many parts
of the continent.
The conditions requisite for so great thicknesses of terrestrial sedi-
ment as occur in the Eocene of western North America are not easily
conceived, if the thicknesses are really as great as they have been
thought to be. If the region of sedimentation was in process of
more or less continuous warping, the depressions deepening as the
surrounding lands were elevated, or if troughs or basins of deposi-
tion were produced by faulting, the bottoms sinking while their sur-
roundings rose, the conditions for thick sediments would be met. It
has sometimes been urged that such formations as those of the Eocene
of the west are too thick to be subaerial, but it is not apparent that
it is more difficult to account for thick subaerial sediments, under the
conditions indicated, than to account for thick lacustrine or even
marine formations.
The relations of the Eocene beds accumulated in lakes or on the
land are such as to indicate that both the attitude and the altitude
of the surfaces in the western half of the continent were very different
from those which now exist. The western part of the continent must
have been, on the whole, much lower than now, and, locally and
temporarily at least, without well-established drainage. The present
1 King, op. cit., p. 541.
214 GEOLOGY.
mountains were certainly not so high as now, though considerable
elevations and great relief must have existed to furnish the abundant
sediments.
Close of the Eocene in North America. — The closing stages of the
Eocene were marked by crustal movements in the west, resulting in
considerable changes in geography. Such movements had been in
progress throughout the period, as has been indicated, but the changes
at the close were on a larger scale. The deformative movements
seem to have included faulting and folding, as well as general crustal
warping. The results of these movements were the withdrawal of
the sea from the lands which it had covered along the Pacific coast,
and the development of new areas of high and low lands, and there-
fore a shifting of the areas of rapid degradation and aggradation.
Among the deformations connected with the close of the Eocene were
the renewed upbowing of the Klamath mountains,1 the beginning
of the development of the Coast range of Oregon,2 and the notable
deformation (folding) of the newly deposited sediments in central
Washington,3 and in the Santa Cruz mountains of California.4 In
and about the Basin region,5 faulting, rather than warping and
folding, seems to have been the prevalent phase of deformation, though
the faulting at the close of the Eocene is not always separable from
that of later times. In Colorado, deformation at the close of the
Eocene is recorded at numerous points,6 with the general result that
degradation succeeded aggradation in some places, while the change
was reversed in others. Faulting and warping also seem to have
occurred in New Mexico and Arizona at about the same time, resulting
in changes which stimulated erosion in those regions in the epoch
which followed. These crustal movements seem to have been con-
nected, in more than an accidental way, with an increase in the vigor
of igneous activity, as shown by the extrusions of abundant igneous
rock near the close of the period.
Outside the Cordilleran region there were lesser changes. Along
the Atlantic and Gulf coasts the Miocene is in many places uncon-
1 Diller, Bull. 196, U. S. Geol. Surv.
2 Diller, Port Orford, Ore., folio, U. S. Geol. Surv.
3 Smith (G. O.), Mount Stuart, Wash., folio, U. S. Geol. Surv.
4 Ashley, Jour, of Geol., Vol. Ill, p. 434 et seq.
5 Button, Mono. II, U. S. Geol. Surv., and King, op. cit., p. 541.
8 See Colorado folios of the U. S. Geol. Surv.
THE EOCENE PERIOD. 215
formable on the Eocene, and it was at the close of the Eocene (or per-
haps during the Oligocene) that an island, now included in the penin-
sula of Florida, was formed. In the Carolinas, and in the western
Gulf region, the conformity between the Eocene formations and those
classed as Oligocene seems to preclude notable changes of geography
along the coast in the southeastern part of the United States, at the
close of the period.
FOREIGN.
Europe. — The Eocene beds of Europe may be grouped in three
principal areas, viz.: (1) The London-Franco-Belgian basin, including
the deposits of England, northern France, Belgium, etc.; (2) those
of south Europe west of Russia, and (3) those of south Russia. This
distribution, when compared with that of the late Cretaceous, shows
that there was a wide-spread withdrawal of the sea from northwestern
and central Europe at or near the close of the Cretaceous period. At
this time Great Britain probably became connected with the con-
tinent, though considerable lakes, estuaries, and perhaps other areas
of deposition remained over western Europe within the area from
which the sea withdrew. Later, but still early in the Eocene, sub-
mergence of the land set in, allowing the sea to again overspread con-
siderable areas from which it had been temporarily excluded. In
western and central Europe the maximum submergence of the Eocene
seems to have been accomplished by the middle of the period (Fig. 425).
Toward its close, the epicontinental waters of the northwestern part
of the continent were again restricted. It follows that in the earliest
stages of the period, the epicontinental deposits in the northern and
central parts of the continent were largely of fresh- and brackish-water
origin; that those of a later stage were more generally marine; while
those of still later stages were largely non-marine. The geographic
changes in southern and eastern Europe at the close of the Cretaceous
period seem to have been less considerable.
The interval of rather general emergence in northwestern Europe,
following the close of the Cretaceous, must have been a somewhat
protracted one, for the next marine deposits (mid-Eocene) of this
region carry a fauna notably different from that of the Cretaceous
beds below. During this interval, the Mesozoic types of life (except
the lower forms) gave place to modern ones. In many places, too,
216
GEOLOGY.
the Cretaceous beds were deeply eroded before the deposition of the
overlying Eocene. The break between the Cretaceous and the Eocene
was long regarded as one of the great breaks in the geological record,
but the hiatus is partially and imperfectly bridged by the estuarine,
lacustrine, and other deposits of the Early Eocene. It is not to be
FIG. 425. — Sketch-map of Europe, during the Eocene, Lutetian stage. The shaded
portions represent areas of deposition. (After De Lapparent.)
lost sight of that the one period merged insensibly into the next, even
though the strata which recorded the transition may not be found
in every region. In southern Europe, the separation of Cretaceous
and Eocene is much less sharp, showing that the notable geographic
changes of the western region did not affect the southern and south-
eastern parts of the continent, or at least not to the same extent.
To the early Eocene lakes, estuaries, and other sites of deposition,
in western Europe, and later to the sea which covered a part of the
same area, considerable streams flowed from the surrounding lands.
Into the arm of the sea which covered parts of England, France, and
THE EOCENE PERIOD. 217
Belgium before the close of the Lower Eocene, the drainage from east-
ern Britain and Norway1 brought plants (palms) and animals (croco-
diles, alligators, etc.) now characteristic of tropical latitudes. The
Tertiary of the Paris basin especially is famous for its wealth of fossils.
The Lower Eocene of this basin is largely of non-marine origin, and
contains some coal; the Middle is marine, and includes both nummu-
litic limestone and glauconitic beds; while the Upper is marine below,
but non-marine above.
The Eocene of central and western Europe is mostly of clastic origin,
and the beds are still unindurated. The aggregate thickness of the
system in England is about 1700 feet.
In southern Europe, the Eocene sea spread much beyond the borders
of the present Mediterranean, covering much of the southern part of
Europe. It also overspread the northern part of Africa and part of
southeastern Asia. Connecting freely with the Indian Ocean, it cut off
the southern peninsulas of Asia from the continent to the north. In
western Europe, an arm of the Mediterranean sea swung around the
north side of the Alps and Carpathians, and extended thence eastward,
connecting in that direction with the water which covered much of
southern Europe. A narrow sound east of the Urals probably con-
nected the Arctic ocean with this expanded Eocene Mediterranean.
Out of this extended sea rose many islands, some of which corresponded
in position to the Alps, Carpathians, Apennines, and Pyrenees.
On the bottom of this great body of water, which should perhaps
be thought of as a part of the ocean rather than as a Mediterranean
sea, limestone was deposited on an extensive scale. Much of it is made
up almost wholly of the shells of nummulites, a genus of foraminifera,
and is known as Nummulitic limestone. This limestone is known in the
Pyrenees, the Alps, the Apennines, the Carpathians, in Greece and Tur-
key, at various points in northern Africa, in Asia Minor, Persia, Beloo-
chistan, India, Farther India, China, Japan, Java, Sumatra, and the
Phillipines. It is, in short, found from one side of the Old World to the
other. While the limestone is sometimes made up almost wholly of
foraminiferal shells, it often contains other types of fossils in abundance.
The rock is often firm and even crystalline. In this respect the Eocene
of southern Europe is in sharp contrast with the unindurated, new-
1 James Geikie, Outlines of Geology.
218 GEOLOGY.
looking beds of the Paris basin. Since it is often thick, as well as wide-
spread (it locally attains a thickness of several thousand feet), the sea
must have swarmed with foraminifera.
Hardly anywhere else in the rocks of the
whole earth are there indications of such
great numbers of organisms of one type.
The Hippurite limestone of the Cretaceous,
and the Fusulina limestone of the Carbon-
iferous, are perhaps most nearly compar-
able. Fossil nummulites are also found in
FIG. 426. — A bit of nummulitic
limestone. the sandstones, and even in the iron ores
of the period.
In the northern Alps and Carpathians, there is a series of clastic
beds known as the Flysch. The lower portion of the series is believed
to be Cretaceous, but in Bavaria the upper portion is associated with
nummulitic limestone, and is therefore thought to be Eocene. The
peculiarity of this formation is the occurrence within it of gigantic
bowlders, some of which are said to have a diameter of 100 feet. They
occur singly or in groups, and are sometimes embedded in clay, though
more commonly they are a constituent of conglomerate. Some of the
bowlders are foreign to the adjacent mountains, and have been thought
to suggest the existence of glaciers. The paucity of fossils is in harmony
with this suggestion, without proving its truth. If this inference be
correct, it would seem that there must have been high mountains in
central Europe, for a low temperature does not appear to have affected
any considerable area of the sea. From high mountains, glaciers might
have descended to low levels, as in New Zealand to-day, where between
latitude 43° and 44° S., glaciers descend to within 500 feet of the sea-
level, and deposit their moraines in a region of tree ferns and palms.1
Against this interpretation much may be said. At any rate the
fossils of the period in the surrounding regions denote a climate too
warm to allow the hypothesis to be accepted, except on the basis of irre-
futable evidence. Similar problems are presented by certain formations
of other periods. In the North Tyrol, the Eocene contains coal. Igneous
rocks of Eocene age are common in Europe as in America.
Some idea of the deformative movements which have taken place since
1 James Geikie. Outlines of Geology.
THE EOCENE PERIOD. 219
the Eocene may be gained from the fact that the nummulitic limestone
occurs at elevations of more than 10,000 feet in the Alps, up to 16,000
feet in the Himalayas, and up to 20,000 feet in Tibet. It is possible
that the Himalayas and Alps had begun their growth before the Eocene,
but the above figures represent their respective minimum post-Eocene
uplifts. The Pyrenees and Carpathians were likewise low in the Eocene
period, their principal elevation being of later date. The Caucasus,
Thian Shan, and other high mountains of Eurasia are also in large
measure of post- Eocene growth. In the Old World, therefore, as well
as in the new, the greater relief features of the present time were still
undeveloped in the Eocene period.
Other continents. — In Africa, marine Eocene is known along the
northern coast, on the west coast, and in Soudan1 (Sokoto). The fos-
sils of Sokoto indicate a connection between the mid-Eocene Indian
ocean, and the waters which overspread Soudan, by way of Egypt.2
In some parts of Egypt, the Eocene is notably unconformable on the
Cretaceous.3 Eocene beds are known in South Australia, New Zealand
and Tasmania, though not generally sharply differentiated from the
later Tertiary. At the head of the Great Australian bight, there is a
thick bed, 250 feet or more, of Eocene chalk. In New Zealand the
Eocene is said to grade into the Cretaceous below without break.
Eocene beds are also known on the island of Luzon,4 in Java, in Bor-
neo,5 and in Japan.6
Of the Eocene of South America little can be said. The Tertiary
formations of this continent have not been closely correlated with those
of other regions. There is marine Eocene along some parts of the
western coast, in Patagonia 7 (Magellanian series), where the beds are
usually unconformable on the Cretaceous, probably in Argentina, and
along at least a part of the coast of Brazil.8 Eocene beds of non-
1 Lelean, Geol. Mag., 1904, p. 290.
2 De Lapparent, La Geographie, Vol. XI, p. 1.
Beadnell, Geol. Mag., 1901, p. 23.
Becker, 21st Ann. Kept., U. S. Geol. Surv., Pt. Ill, p. 552-6.
Becker, 21st Ann. Kept., U. S. Geol. Surv., Pt. III.
Geol. of Japan, Imp. Geol. Surv. of Japan, p. 77.
Hatcher, Sedimentary Rocks of Southern Patagonia. Am. Jour. Sci., Vol. IX,
1900, pp. 97-99; also Geology of Southern Patagonia, idem, Vol. IV, 1897, pp. 334-337.
a Branner, Bull. Geol. Soc. Am., Vol. 13, Stone Reefs of Brazil. Mus. of Comp.
Zool., Bull. 44, pp. 27-53.
220 GEOLOGY.
marine origin also occur in Patagonia.1 Both marine and non-marine
Eocene may be much more widely distributed.
Eocene beds, not always distinctly separable from the Oligocene, are
extensively developed in the West Indies, where limestone is the domi-
nant type of rock. In Cuba,2 the Eocene beds (together with the Oligo-
cene) occupy the surface of about half the island. In Jamaica3 the
Eocene is distinct from the Oligocene. Eocene beds grading up into
Oligocene without interruption are present on the island of Trinidad,
and are extensively developed on the eastern side of Panama,4 and in
Central America. They are partly clastic, and partly limestone. Ma-
terial derived from igneous rocks enters largely into their composition,
and extensive extrusions of basic rocks occurred in this region during
the period. Some idea of the changes of later times may be gained
from the fact that the Early Tertiary formations of the Caribbean
region occur up to elevations of 5000 feet on the mainland, and up to
elevations of 10,500 feet in Hayti.5 The date of the principal deforma-
tion was later than the Eocene.
It was formerly thought that the Atlantic and Pacific oceans con-
nected freely across Panama during the early Tertiary, but the work
of Hill renders it doubtful whether there were more than shallow and
restricted connections in the Eocene, and whether there were connec-
tions of any sort at a later time.
General geography of the Eocene. — From what has been said it is
clear that Eocene geography was very different from that of the present
time, and differences still greater than those already indicated are con-
jectured. North America was perhaps connected with Asia on the
west, via Alaska, and with Europe on the east, via Greenland and Ice-
land.6 Land seems to have failed of making a circuit in the high lati-
tudes of the north only by the strait or sound east of the Urals.
In the southern hemisphere, it has been surmised that Antarctica
was greatly extended, connecting with South America, Australia, and
1 Ameghino, L'age des Formations Sedimentaires de Patagonia, Anales de la
Sociedad Crentipica Argentina, 1903.
2 Hill, Cuba and Porto Rico.
8 Hill, Geology and Physical Geography of Jamaica, 1899.
4 Hill, Geological History of the Isthmus of Panama and Portions of Costa Rica.
Bull. Mus. of Comp. Zool., Cambridge, 1898.
5 Idem.
8 Neumayr, Erdegeschichte Bd. II.
THE EOCENE PERIOD. 221
possibly with Africa. The basis for these conjectures is found in the
distribution of life at that time, as shown by fossils. It has also been
thought that Africa and South America were connected across the
Pacific from some earlier time until after the beginning of the Eocene.1
If these conjectured extensions of land were real, it will be seen that
the division of land and water in the northern and southern hemispheres
was far less unequal than now, and that the land was massed in high
latitudes to a greater extent than at present, while tropical seas were
much more extensive. If extensive polar lands were the cause of
glacial periods, it would seem that the geographic conditions during
the Eocene were favorable in the extreme, if the relations sketched
above were the real ones. In spite of this, the climate of the period
seems to have been genial, and less markedly zonal than now.
Close of the Eocene. — During the later part of this period, and at
its close, there were some notable deformations in Europe. The initia-
tion of the Pyrenees, and of some of the mountains farther east, is
assigned to this time, and the distribution of the later formations, when
compared with the distribution of the Eocene, shows that changes of a
less pronounced type were in progress elsewhere.
THE EOCENE LIFE.
I. The Transition from the Mesozoic to the Neiv Era.
Four salient features marked the transition of life from the Mesozoic
to the Cenozoic era: (1) In marine life, nearly or quite all Cretaceous
species were replaced by new ones; (2) in the terrestrial plant life so
many species lived across the transition interval as to render the plac-
ing of the dividing plane between the Mesozoic and Cenozoic in western
America one of the most mooted of classificatory questions; (3) the
great saurians, from the dinosaurs of the land to the mosasaurs of the
sea, disappeared, and most other reptiles showed profound changes, con-
stituting a revolution in the animals of the land corresponding to that
of the sea, but contrasted with the continuity in the terrestrial vege-
tation; and (4) placental mammals appeared in force and promptly
took a dominant position. The combination is unique, in that, while
half the land life joined with the sea life in undergoing a profound trans-
formation, the other half of -the land life did not notably participate
1 Neumayr, Erdegeschichte Bd. II.
222 GEOLOGY.
in the revolution. In explanation of profound transformations of e pi-
continental marine life, appeal has been made repeatedly to the with-
drawal of the sea, to the extension of the land, and to climatic changes
incident to deformative movements, and this appeal may now be made
so far as the change in the sea life is concerned; but the contrasted
phenomena on the land raises a new and unique question. The with-
drawal of the sea from its wide extension in Cretaceous times seems
in this case peculiarly well fitted to explain the transition in the epicon-
tinental sea life, because of the great differences in the areas of shallow
water in the two periods. It is worthy of note in passing, that the dis-
tribution of the harbors of refuge and other transition tracts of this
transformation had many points of analogy with those of previous
transformations, the Mediterranean region being again conspicuous in
this function. Such repeated service is a most significant illustration,
not simply of the persistency of continents, but of special continental
configurations.
The increase of the land area and the establishment of new land
connections attendant on the post-Cretaceous withdrawal of the sea
might well have caused the vegetation to spread and flourish, if the
climate remained congenial; but why did not the animal life respond
in like manner? The record shows that plant life suffered little, although
plants are on the whole more responsive to climatic and topographic
influences than animals; why, then, did the saurians suffer so much?
Closely correlated with this problem is the question, whence came
the placentals? Had their apparition anything to do with the extinc-
tion of the saurians and the repression of the rest of the reptile horde?
The origin of the placentals is one of the great outstanding problems
of paleontology. It is yet an open question whether the placental
mammals of North America and Eurasia arose from non-placental mam-
mals that had been natives of these provinces in the Jurassic and Creta-
ceous periods, or whether they were immigrants from some other region.
No satisfactory evidence of a transition from non-placental to placental
mammals in Eurasia or North America has yet been produced, but the
imperfection of the record may be appealed to. The relative sudden-
ness and overwhelming power of the placental irruption suggest inva-
sion from some other quarter in which the earlier evolution of the pla-
centals had been in progress for a long time previously; whether from
marsupial or from independent stock, we need not here inquire. The
THE EOCENE PERIOD. 223
deformative movement which closed the Cretaceous period and inau-
gurated the Eocene quite certainly made many new land connections,
and furnished the conditions for a migratory invasion, if, in any of the
previous areas, a mammalian stock of the requisite potentialities was
awaiting the opportunity.
Some of the hypotheses of the place of origin of the placentals look
to relatively isolated areas within the northern hemisphere. Some
special fitness may be assigned to one of these, the old lands of north-
eastern North America, the area in which the angiosperms probably
originated. During the larger part of the Cretaceous period this was
isolated from the western portion of the continent by the great " mediter-
ranean" sea of the Great plains region. In such intervals as there
may have been between the actual sea occupancy of this tract, it was
the site of extensive lowlands interrupted by lakes, swamps, and plex-
uses of streams, more inviting to reptiles than to upland mammals.
Unfortunately, the Cretaceous record of the old northeastern lands is
almost entirely wanting. We have already noted that the deploy-
ment of the angiosperms in that region invited a biological revolution
which did not seem to be registered during the Cretaceous. The
hypothesis that the placentals were evolving there during the Creta-
ceous responds to this obvious fitness of things. A dispersion from
this area, when the deformative movement at the close of the Creta-
ceous made the requisite land connections, is not inconsistent with the
fact that the earliest American deployment of placentals is recorded
in the Puerco beds of Colorado and New Mexico, and the earliest Euro-
pean in the Cernaysian formation of France, and that these were fol-
lowed by the more pronounced and cosmopolitan dispersion which
took place in the Wasatch epoch, when "'the correspondence between
the mammals of Europe and North America was never closer." 1
As an alternative view, an originating tract for the placental mam-
mals has been postulated in the high northern latitudes, partly on the
theoretical presumption that the oncoming of cool climates would
earliest affect that region, and partly because not a few of the migra-
tory paths of the Tertiary mammals seem to have trended southward.
As, however, the land connections between Eurasia and North America
seem to have been wholly in high latitudes, it is difficult to distinguish
between what might have been migrants from a neighboring continent,
1 Scott, Introduction to Geology, p. 505.
224 GEOLOGY.
and what might have originated in the high-latitude area, since both
of these would necessarily move southward in invading the continental
regions where their relics are chiefly found.
All hypotheses that postulate an origin in Eurasia or North America
are somewhat, though not absolutely, dependent on the hypothesis that
the placentals descended from the non-placentals of these regions. Some
paleontologists have, however, entertained the view that the placental
and non-placental branches diverged from a common stock at an early
stage, probably far back in Mesozoic times. This view lends whatever
strength it may have to the hypothesis that the placentals arose in
some region whose record has not yet been carefully studied, because
the transition forms do not appear, at least in sharp definition, in the
European or the American Mesozoic record.
Of such uninvestigated regions, Africa presents the most favor-
able antecedents for placental origination. Australia is excluded,
because placentals do not seem to have ever lived there, until recently
introduced, and South America also, for its placentals seem to be pro-
vincial and limited in type-range, as though they were the offspring of
a branch that became isolated early and developed by itself. The com-
mon parents of all placentals should be rather markedly comprehensive.
South America seems also to have been in migratory relations with
Australia after the appearance in other lands of the primitive placentals,
for carnivorous marsupials of comparatively recent Australian types
lived there. In Africa, on the other hand, the placentals are compre-
hensive in type -range, are highly developed, and widely deployed, and
have a remote mammalian ancestry, with living relics of primitive stock.
It will be recalled that in the Permo-Triassic times, when the amphib-
ians were deploying into the ancestral branches from which all reptiles,
birds, and mammals have probably descended, the Karoo beds of South
Africa displayed an extraordinary vertebrate fauna in which the mam-
malian strain of reptiles was a conspicuous feature. More definite fore-
shadowings of the coming mammalian race were shown there than
anywhere else, notwithstanding the relative scantiness of our knowl-
edge of the "'dark continent." At present, Africa is almost the sole
home of the least modified survivor of one of the great branches of the
primitive placentals, the Condylarthra, in the form of the hyrax, the
coney of the Bible, which has crept out into Syria, but is otherwise
confined to Africa, where one species is found in the northeast, one on
THE EOCENE PERIOD. 225
the west coast, and two in South Africa. It has been demonstrated
recently that the proboscideans originated in Africa, and did not emigrate
until about the Middle Tertiary. These and other considerations that
must here be passed by give some plausibility to the view that the
placentals had their early evolution in the dark continent during Meso-
zoic times, and emerged thence and overran the other continents at the
opening of the Cenozoic era. Some part of this plausibility doubtless
lies in our ignorance of what took place in "'darkest Africa" in this
era, a plausibility that is not without its dangers.
All these suggestions rest on a slender basis of evidence and have
their chief value in giving interest and suggestiveness to the remark-
able facts connected with the disappearance of the great Mesozoic
dynasty of reptiles, and the apparition of the placentals.
The rise of placentals was an assignable agency for the downfall of
the reptiles, though it cannot be affirmed to have been the actual cause.
The placental habit of bringing forth relatively mature offspring, and of
nourishing and protecting them, was in itself an immense advantage to
the race. The eggs of the reptiles were wholly passive subjects of prey,
and during the immature stages after hatching, the young were proba-
bly without any intimate relations to the parent for either nourishment
or defense. To this great advantage of the placentals at the beginning
of life, were added superior agility, as a rule, and higher brain power.
It is not surprising, therefore, that the placental invasion resulted in
the clumsy, affectionless, small-brained reptiles being driven either
into extinction, or into the sedges and rushes, the swamps and lagoons,
the coverts of the jungles, the crevices of the rocks, and the various
by-ways which the placentals cared least to frequent, and that they
have been kept there to this day.
In a way not implied above, the angiospermous flora may have
been a factor in the placental dispersion through the fact that it is the
staple source of food of the mammals. It may have been the dispersion
of this flora from its originating tract, until it came into contact
with the primitive placentals in their originating tract, that caused the
rapid spread and evolution of the latter, on a principle often illustrated
in human experience, of which perhaps there is no better example than
the recent spread of the Colorado potato-beetle when touched in its
native region by the western spread of the potato-plant, through the
agency of the chief of placentals. This would shift the importance of
226 GEOLOGY.
the land connections from migratory facilities for the animals, to their
function in plant distribution. Not only because of this possible func-
tion of the vegetation, but because of its incontestible agency in direct-
ing the evolution of the mammals, we turn to it first in sketching the
life of the Eocene.
The Eocene Vegetation.
In plant history, the Eocene was not eocene, the dawn of the recent,
for the great change from the medieval to the modern, in its main
essentials, had taken place in the Early Cretaceous. The Eocene was
not even the period of any radical innovation. There was, however,
much progress toward the specific forms that now live, and toward the
more recent adaptations to climate, soil, and topography, and toward
those relationships of plant to plant that have worked out into the
present plant societies. In Cretaceous times there was much mixture
of forms that have since become dissociated, and the mixed state con-
tinued in large measure through the Eocene. On account of this mix-
ture, climatic inferences have to be drawn with some caution. Where
palms and poplars grow together, it is not quite clear whether the pres-
ent environment of the palms or that of the poplars is implied. Very
likely conditions not quite like either of these are implied, but rather
climates of a less differentiated or less diversified nature.
The temperate (?) flora of the earliest Eocene. — The plants of the
Heersian system (Heers, Belgium), the earliest known Tertiary flora of
Europe, interpreted from the present adaptations of the species, imply
a temperate climate. Most abundant among them were oaks like those
of the present elevated districts of warm temperate zones. With these
were associated willows, chestnuts, laurels, ivies, aralias, and other plants,
making up an interesting group which Saporta likens to that of southern
Japan, and Prestwich regards as very different in significance from the
tropical palms, tree-ferns, and associated plants of a later stage of the
Eocene. An assemblage of similar temperate facies occurs in the Paris
basin, and in the Lower Eocene of England. The American flora of this
stage yet awaits determination.
The tropical (?) flora of the Middle Eocene. — In a later stage of the
Lower Eocene (London clay), a rich assemblage of trees grew in England,
embracing palms, figs, cinnamon, and many others which, interpreted
by present ranges, imply a somewhat tropical climate. In the Middle
THE EOCENE PERIOD. 227
Eocene, the prolific Alum Bay (England) plant-beds record a flora
" the most tropical in general aspect which has yet been studied in
the northern hemisphere/' 1 while the abundant Bournemouth (Eng-
land) flora, perhaps a little later " suggests a comparison of its climate
and forests with those of the Malay Archipelago and tropical America/7
It was an epoch of palms in mid-latitudes. The Mid-Eocene series of
America in temperate latitudes contains palms and bananas mingled
with many similar mild temperate trees, implying sub-tropical or warm-
temperate conditions.
Some of the leading plants of the middle and late Eocene of Europe
and America were allied to types that now prevail in India and Aus-
tralia, and hence the Eocene flora is often said to have had an Australian
facies, an expression liable to misinterpretation. The facts do not im-
ply that these types originated in Australia, or were even necessarily
living there in Eocene times, but merely that the descendants of the
Eocene plants now live there. It is the more needful to observe this,
because the nearest living relatives of another part of the Eocene plants
of America and Europe are now found in portions of tropical Africa
and America, while those of still another part are found in temperate and
even boreal latitudes in America. An adaptive differentiation seems
to have taken place since, attended by a dispersal of the differen-
tiated groups to different climatic zones. Probably the true view is
that the mixed or undifferentiated flora of the Cretaceous and Eocene,
when it came to be subjected later to severe climatic and other crucial
conditions, became modified into adaptive groups, some of which came
to be restricted to the tropical regions and are now known as tropical
plants, others to the temperate, and still others to boreal regions, ac-
quiring corresponding designations. These later meanings can be car-
ried back to the ancestral plants only at a certain risk of error. It is
doubtless wise to make some discount in the direction of intermediate
conditions, the conditions from which all probably diverged.
The flora as food-supply. — The presence of the angiospermous flora
in the northern continents at the time of the appearance of the placental
mammals, without doubt had far-reaching biological consequences. The
rapid development of the ancestral herbivores, rodents, sloths, and
lemurs, was doubtless, in some large measure, controlled by adaptation
1 Geikie, Text-book of Geology, 3d ed., p. 974.
228 GEOLOGY.
to the different edible portions of the angiosperms. Grasses had
appeared in the Cretaceous and were present during this period.
Although the evidence is too scanty for positive affirmation, it is not
improbable that the shifting lakes and meandering rivers of the
Eocene gave rise to sedgy meadows and grassy plains, and through
these 'aided in the evolution of the grass-feeding herbivores and, as a
secondary consequence, led on to the evolution of the carnivores that
preyed upon them. It can scarcely be doubted that the sweet foliage
of the angiosperms proved a more congenial food for mammals than
the needles of the conifers, or the coriaceous and bitter foliage of the
pteridophytes.
The Land Animals.1
The undifferentiated nature of the early Eocene placentals. — It is
scarcely possible to carry our familiar conceptions of the mammalian
orders back to the Eocene prototypes, without importing distinctions
which did not then exist except as potentialities. The earliest Eocene
mammals were much more primitive and obscurely differentiated than
even those of the Middle Eocene, and this rapid backward convergence
1 For the more important literature on the American Tertiary Mammalia, see the
numerous papers of Cope, Marsh, Osborn, Scott, Wortman, Matthew, and others,
particularly; Marsh: Introduction and Succession of Vertebrate Life in America,
Proc. A. A. A. S., Vol. XXVI, 1878, p. 211. The Origin of Mammals, Am. Jour. Sci.
Vol. VI, 1898, pp. 406-409, also Geol. Mag., Vol. VI, 1899, pp. 13-16. Cope: Ver-
tebrata of Tertiary Formations of the West, U. S. Geol. Surv., Vol. Ill, 1884. Osborn:
The Rise of Mammalia in North America, Am. Jour. Sci., Vol. XLVI, 1893, pp. 379-
392, and 448-466; the Evolution of the Teeth of Mammalia, Trans. N. Y. Acad. Sci.,
Vol. XII, 1894, p. 187; the Origin of Mammalia, Kept. Brit. A. A. S., 1897, pp. 686-
687; also Am. Nat., Vols. XXXII and XXXIV, 1900, pp. 943-947, and Am. Jour.
Sci., Vol. VII, pp. 92-96, 1899, and many other papers. Scott, On the Osteology
of Mesohippus and Leptomeryx, with observations on the modes and factors of evo-
lution in the Mammalia, Am. Geol., Vol. IX, 1892, p. 428; Osteology and Relations
of Protoceras, Jour. Morph., 1895, pp. 303-374. Wortman: North American Origin
of the Edentates, Science, Vol. IV, 1896, pp. 865-866; the Ganodonta and their Rela-
tions to the Edentates, Bull. Am. Mus. Nat. Hist., Vol. IX, 1897, pp. 59-100; the
Extinct Camelidse of North America, Bull. Am. Mus. Nat. Hist., Vol. X, 1898, pp.
93-142. Matthew (W. D.), A Provisional Classification of the Fresh-water Tertiary
of the West, Bull. Am. Mus. Nat. Hist., Vol. XII, 1900, pp. 19-75; Ancestry of Cer-
tain Canidse, Viverridse, and Procyonidse. Adams (G. I.) : The Extinct Felidse of
North America, Am. Jour. Sci., Vol. I, 1896, pp. 419-444, and Vol. IV, 1897, pp.
145-149.
THE EOCENE PERIOD. 229
seems to point to some set of conditions which caused an exceptionally
rapid deployment of the great class at this stage, whatever their previous
history had been. The coming into a new domain of rich and varied
conditions, whether by immigration or indigenous development, may
be safely included among these conditions.
The very earliest Eocene placentals, so far as they can be inter-
preted from the remains in the basal Eocene (Puerco beds of America
and Cernaysian of France), constituted an assemblage of groups quite
vaguely differentiated, in which the present orders were rather fore-
shadowed than distinctly expressed. The present great groups of
herbivores were foreshadowed by the Condylarthra, and the carnivores,
by the Creodonta, but these were not sharply distinguished, both
classes being five-toed plantigrades, the ends of whose phalanges were
armed with horny coverings that were neither quite hoofs nor claws.
Thus the first stages of the now pronounced division into the ungulates
and the unguiculates were only obscurely indicated. So obscure are
the relationships of the ancestral edentates, the Ganodonta, that they
have only been recognized recently through the critical studies of Wort-
man and Osborn. The insectivores were not more definitely charac-
terized, and Eocene genera were referred to the order Insectivora and
later withdrawn by the early paleontologists, because of their uncer-
tain limitations and imperfect differentiation. The definition of the
ancestral lemuroids was equally imperfect. All these orders seem, how-
ever, to have been represented in this obscure fashion. The rodents
have not been recognized in the Puerco beds, though present in the
Wasatch.
But so rapid was the early evolution that before the close of the
Eocene, the Herbivora (Ungulata), Carnivora, Edentata, Insectivora,
Rodentia, Quadrumana, Cetacea, and Sirenia, and probably the Cheirop-
tera were distinctly defined. Progress was even made in the evolution
of some of the suborders and families. It seems to have been a most
remarkable instance of rapid evolution. None of the present generaf
however, are known as early as the Eocene. When it is recalled that
the name Eocene was founded on the presence of some species of living
invertebrates, the great difference between the stage of evolution of the
invertebrates and of the placentals may be realized.
From this general view we may turn to some of the salient facts rela-
tive to the evolution of the several orders.
230
GEOLOGY.
The main herbivorous line. — While the condylarths and creodonts
were structurally near one another at the opening of the period, it was
not long before a clear distinction arose between their respective deriv-
atives, the hoofed herbivores (ungulata) and the clawed carnivores (un-
guiculata). The condylarths were small generalized forms with five
toes and forty-four teeth, not yet developed into the true herbivorous
type, but displaying differentiation in that direction. The accompany-
ing figure shows the general features of the skeleton of one of the best-
FIG. 427. — A primitive ungulate or condylarth from the second Eocene epoch
(Wasatch) Phenacodus primcevus Cope, about TV natural size (about the size of a
tapir), from Big Horn basin, Wyoming. (After Cope.)
known genera (Phenacodus). Without radical change, the condylarths
have lived on till the present time, but a branch seems to have di-
verged early, and to have deployed rapidly into the ungulates. This
branch seems to have consisted of small five-toed forms adapted to for-
ests and marshes where succulent vegetation afforded an easy sustenance.
In the course of the period many of them became gradually fitted for
life on the grassy plains. To this end, hard hoofs and powerful grinding
teeth, capable of masticating coarse, dry herbage, were developed. The
canine teeth gradually disappeared, and the molar and pre-molar teeth
assumed flat, corrugated crowns seated on well-developed roots. The
frontal teeth were variously adapted to cropping vegetation. In the
foot there was a progressive abandonment of the flat heavy palmate
THE EOCENE PERIOD. 231
form, and the assumption of the light springy digitate habit, doubtless
through the need of a quick start and a swift flight to escape the car-
nivores that were also abandoning the palmate form for the digitate.
There was thus a sharp competition for increased speed, on the one hand
to escape, and on the other to overtake, and on both sides there was a
rising up on the toes with an increase of length of limb and a gain in
elasticity. The evolution of the hoofs and of the grinding teeth have
been thought to be intimately associated with an increased prevalence
of grassy plains. As we have seen, the grasses were present in some
abundance as early as the later Cretaceous 1 at least, and they had by
this time been given ample opportunity to spread widely, and to fasten
upon suitable ground and hold it with that remarkable virility and
tenacity which is characteristic of the grasses, and which has made them
so important a factor in modern food supplies. The firm turf which
the grasses give is quite in contrast with the soft soil of the forests and
ungrassed marshes. Because grasses are also much associated with dry
and even semiarid grounds, dessication intensifies the firmness of the
bottom, and gives additional occasion for the hoof. The tenacious fiber,
the siliceous stiffening, and the dryness of the grasses at certain seasons,
doubtless gave occasion for effective cropping incisors and grind-
ing molars. The foliage of the angiosperms, which was more available
for fodder than the needles and spines of the previous gymnosperms and
pteridophytes, gave occasion for similar cropping and grinding teeth,
and lent their influence to the transition, but served to retain in the
forests a notable section of the evolving order.
Back of these influences lay the physical conditions that promoted
them. In the western American region, where the evolution is best
known, the great lakes and meandering rivers were characteristically
undergoing shif tings. If these followed the method of like modern agents,
they left behind them, as they shrank or shifted, a border of grassy or
sedgy ground which, on fuller drainage, often became prairie, though
this is not the sole explanation of prairies. Such changes were peculiarly
suited to the evolution of herbivorous prairie life, and this in turn must
have invited its appropriate contingent of predaceous animals. If these
considerations be valid, the prime factors in the evolution of the ungu-
lates were (1) an undifferentiated plastic animal group susceptible of
1 Dawson, Plant Life, p. 195.
232 GEOLOGY.
modification (a branch of the primitive Condylarthra in particular);
(2) a plant group susceptible of becoming advantageous food for the
new type, notably the grasses and subordinately the fodder-furnishing
angiosperms; and (3) the shrinkage and shifting of lakes, marshes, and
lodgment plains, and the drying up of the plains of the continent, result-
ing in prairies whose open field and hard turf invited the development
of foot and limb modification in the interest of the greatest speed. The
era of simple bulk and heavy armor had largely passed, and an era of
agility, dexterity, and of light but effective weapons had begun. No
small factor in this progress was the increase in intelligence disclosed by
the larger brains. Intelligence henceforth proved an advantageous sub-
stitute for mass and mere brute strength. Corresponding with the
lighter and more agile structure there was the development of smaller,
simpler, but more effective weapons of attack and defense. Size never-
theless continued to be a factor of importance, and some species in
almost every suborder grew in bulk until they reached and passed the
point of mass-advantage, and thereafter declined.
Side branches that became extinct. — In the course of the early evolu-
tion some notable forms appeared, and a little later, became extinct.
Of these the Amblypoda (blunt feet) took precedence for a time. They
were a rather low type with diminutive, smooth brains, heavy bodies,
stocky limbs ending in stumpy five-toed feet, with a partly digitate
habit. They reached elephantine size; indeed they were much such
a development of massiveness and clumsiness on the mammalian stem,
as the dinosaurs had been on the reptilian stem, but the times did not
equally favor their dominance and perpetuity. The most prominent
offshoot from the Amblypoda in the Lower Eocene was the Coryphodon
(Fig. 428). Near the middle of the period (Bridger epoch) the remark-
able Dinoceras (terrible horn) appeared, followed later in the epoch by
Tinoceras, with which the line of the Amblypoda seems to have become
extinct. The Dinocerata (Fig. 429) were grotesque monsters whose
skulls were armed with three pairs of protuberances perhaps horn cores,
and a pair of enormous canine teeth or tusks projecting below, at least
in the male, an extravagant attempt at armature on both upper and
nether sides, but with meager results, if the short history of their endur-
ance is a true index. Their brains were smooth and singularly small
for such ponderous bodies. All mammalian brains of the time were
diminutive and simple, compared with later forms (see Fig. 430), but
THE EOCENE PERIOD.
233
in the Dinoceras, brute-mass and low brain-power seem to have reached
their mammalian climax, much as they had reached an earlier climax
in the monster reptiles. Nearly all dominant forms thereafter showed
FIG. 428. — One of the Amblypoda of the Lower Eocene (Wasatch) Coryphodon hama-
tus, restoration of skeleton by Marsh. About TV natural size. For skull and
brain see Fig. 430a. From Wyoming. (After Marsh0)
notable increase in the size and complexity of the brain, and from this
time on there was a gradual transition from the dominance of brute-
force to the dominance of the brain-power.
FIG. 429. — Dinoceras mirabile, restoration of skeleton by Marsh, about 13 feet long,
Middle Eocene, Wyoming. (After Marsh.)
The divergence of the ungulates into odd- and even-toed. — Early in
the Eocene, the hoofed animals began to diverge into their present divi-
sions, the odd-toed (perissodactyls) and the even-toed (artiodactyls).
234
GEOLOGY.
The distinction is not so much a matter of toes as of mode of support.
In the odd-toed, the main line of support lies in the axis of the middle
toe (Mesaxonia) ; in the even-toed, it lies between the third and fourth
toes (Paraxonia) ; in other words, one main line of support in the first
case, and two in the second. In the course of time, the lateral toes fell
FIG. 430. — COMPARISON OF BRAINS. EOCENE BRAINS: a, Coryphodon hamatus; 6,
Tinoceras pugnax. MIOCENE BRAINS: c, Eporeodon sociates; d, Elotherium crassum.
PLIOCENE BRAIN: e, Platygonus compressus.
(After Marsh.)
MODERN BRAIN: /, Auchenia vicugna.
out of use and were atrophied. The first class reached its extreme type
at length in the horse, and the second in our cloven-hoofed cattle. But
these perfected types were not attained in this period, which only wit-
nessed the initial divergence. The original five spreading toes were not
so advantageous on hard, grassy ground as a strong, concentrated line
of support through the center of the foot, and as the toes were no longer
THE EOCENE PERIOD. 235
used for grasping or digging, as in the case of the carnivores, they gradu-
ally dwindled away. On the whole, the two-toed system seems to
have proved the best; at least the artiodactyls are now much the more
numerous.
The evolution of the perissodactyls did not pass beyond the three-
toed form during the Eocene period. The three present types, the
tapir, the horse, and the rhinoceros, were, however, distinctly fore-
shadowed. The most undifferentiated of the early perissodactyls were
the lophiodonts, which seem to have graded almost insensibly into the
ancestral tapirs (Systemodori) , horses (Hyracotherium), and rhinoceroses
(Hyrochinus). The first definite steps in the development of the horse,
which has become a classic example of evolution, appeared in the second
stage of the earlier Eocene (Wasatch), no traces having yet been found
of the equine line in the Puerco. The earliest recognized form was the
Hyracotherium (Fig. 431), whose equine characters are quite obscure.
FIG. 431. — An early ancestor of the horse family, Hyracotherium (Protorohippus)
venticolum, from the Lower Eocene (Wind River formation) of Wyoming, £ natu-
ral size. (Skeleton restored by Cope.)
Pachynolophus represented a slight step in advance, and the Orohippus
(Epihippus) a more decided step. The latter was four-toed in front
(three functional) and three-toed behind, and the limbs and teeth were
slightly modified in the direction of the horse. These forms were about
the size of a small dog, and as nearly canine as equine in appearance.
The evolution continued through the remaining periods of the Tertiary,
the true horse only appearing in the Pliocene. The primitive Eocene
236 GEOLOGY.
forms lived both in Europe and America, and the evolution seems to
have gone forward along much the same lines in both countries; but
how far this implies free intermigration and how far parallel evolution
is a mooted point.
The rhinoceros family appears in the record a little later than the
tapirs and horses, and, although recognized in the later part of this
period, had its development chiefly in the next.
A notable side branch of the tapir-horse-rhinoceros stem appeared
in the later part of the period in the form of the titanotheres, which, in
the next period, reached titanic dimensions and then soon became extinct.
The deployment of the artiodactyls. — The even-toed division
emerged from the generalized type more slowly. Of the four present
groups, Pecora (cattle, sheep, deer), Suina (pigs, peccaries, hippopota-
muses), Tylopoda (camels, llamas), Tragulina (chevrotains), the second
was represented in the Bridger epoch by a primitive hog (Homacodon)
which was much smaller than the modern hog, and had strong canine
teeth of somewhat carnivorous aspect. Strangely enough, the ancestral
camels seem to have developed on the American continent in the mid-
dle and later Eocene, and to have flourished here until the Pliocene,
when, having previously sent a branch to South America to evolve into
llamas and vicunas, and another into the Old World to become the
present camels, they died out in their primitive home. The forerunners
of the ruminants appeared in a group of partially differentiated forms
(Ccenotheridce and Xiphontidce) , and there was also a rather notable
group of small artiodactyls, the oreodons, that seem to have left no
descendants.
Amid all these changes in the more progressive branches of the con-
dylarths and their descendants, the primitive type of condylarths lived
on with minor modifications, but after the earliest Eocene, it became
markedly inferior to its own more progressive kin.
The development of the carnivores. — As already noted, the ances-
tors of the carnivores, the creodonts, were not sharply distinguished
from the primitive ungulates, the condylarths. It has been thought
by some paleontologists that the creodonts were the more primitive
stem, and that the condylarths diverged from them, as also the eden-
tate and rodent branches. This would give the creodonts the central
position among the primitive mammals. It has been suggested that
they themselves may have branched off at an earlier date from some very
THE EOCENE PERIOD.
237
unspecialized insectivores. These views are chiefly valuable for their
suggestiveness. The creodonts ranged throughout the whole period and
passed into the next, gradually giving way meanwhile to their own more
progressive offspring. They were common in America and in Europe,
and there is evidence that they lived also in South America. The spe-
cial modes of divergence of the present families is yet largely undeter-
mined. There were anticipatory forms in the basal Eocene, but the
modern types only began to emerge definitely toward the end of the
period. Patriofelis, "the father of cats/' a name not to be taken too
FIG. 43 la. — Mounted skeleton of Patriofelis, a Creodont from the middle Eocene
of Wyoming; TV natural size. (After Osborn.)
literally, of the Bridger epoch, presented a suggestive combination of
characters, some features resembling those of the Felidce and others
those of the seals. Some species seem to have been aquatic. Primi-
tive representatives of the dog family (Canidce), thought to be descend-
ants of the Provivera branch of the creodonts, appeared in Europe
in the late Eocene period. The Mustelidce (otters, badgers, and weasels)
and the Viverridce (civets, ichneumons, and their allies) appear to have
had a common ancestral form in the early Eocene, and to have diverged
in the later portion. There were ancestral weasels in the latter part of
the period, as well as primitive viverroids. The ancestral hyenas ap-
peared about the same time in Europe and Asia. The cat family had
a forerunner in Eusmilus of the Upper Eocene of France, though but
238 GEOLOGY.
little is known of the cats until the Miocene, when they were abun-
dant and wide-spread.
The emergence of the edentates. — The ancestral edentates, the Gano-
donta, were very similar in general appearance to the Condylarthra and
Creodonta, but their dentition and certain peculiarities of structure
brought to knowledge by the researches of Wortman and Osborn have
led to the recognition of their edentate relations. The slight degree of
differentiation in the earliest Eocene seems to imply that the three orders
had but recently diverged from their common ancestors. Wortman
holds that the South American edentates were derived from these north-
ern forms and that there must hence have been a land connection about
the time of the early Eocene, which permitted their migration. It is
not mprobable that such a connection was formed during the transi-
tion epoch from the Cretaceous to the Eocene, which might have con-
tinued long enough to serve this function without permitting a migra-
tion of all forms.
The ancestral rodents. — In the early Eocene there were very primi-
tive rodents whose incisors had just begun to assume their specific gnaw-
ing functions. By the middle of the period they became a notable factor
FIG. 432. — The skull and jaw of a large Eocene rodent, Tillotherium fodiens Marsh,
from the Bridger formation, Wyoming, about £ natural size.
of the fauna in the form of tillodonts, the Tillotherium of the Bridger
formation having finely specialized incisors (Fig. 432). For a rodent,
this was a large animal, half the size of a tapir. The primitive squirrel
type appeared in Europe in the latter part of the period. Even to-day,
the rodents retain many primitive characters, and since the Miocene
they have undergone few radical changes. This slow evolution implies
THE EOCENE PERIOD. 239
that they may have extended farther back than the record indicates.
Their derivation is not yet determined.
The primitive insectivores. — Most of the present families of insec-
tivores can be traced back to the Eocene. They retain even to this
day many of their primitive characters, agreeing with the creodonts in
their low type of brain and in some skeletal features. They are the
least altered of the great branches, and have been thought to most
nearly represent the character and habits of the primitive placentals,
but this remains an open question.
The primates (Quadrumana). — Of the higher order of the primates,
the apes, no traces have yet been found in the Eocene deposits, the
earliest apes appearing about the middle of the Miocene. Of the lower
division, the lemuroids, representatives appeared in the Wasatch in
America and in a similar horizon in Europe, a distribution which is the
more notable as the lemurs are now confined to Madagascar and to
portions of Africa and southern Asia. The progress of investigation is
gradually filling up the gap between the lemuroids and the apes, and
there is now little doubt that the apes are descendants of the early
lemuroids. The latter show many affinities to the insectivores, and were
possibly derived from them. The Anaptomorphus from the Wasatch of
Wyoming had large cerebral hemispheres of the type characteristic
of the primates. This must have contrasted strongly with the small
smooth brains of the contemporaneous creodonts and condylarths and
their derivatives.
The mammals go down to sea. — Just as the land reptiles of Meso-
zoic times took to the sea by choice or by necessity, so did the mammals
in Cenozoic times, and thus arose the cetaceans (whales, dolphins, por-
poises), the sirenians (mana tees, dugongs), and the pinnipeds (seals, sea-
lions). Some suggestion of the possible origin of the last is found in
Patriofelis, but the source of the cetaceans and sirenians is quite uncer-
tain. The latter have not yet been found in the Eocene deposits, but
the primitive cetaceans had representatives in the Zeuglodons, whale-
like animals of great length, whose limbs had become fully adapted to
an aquatic life, but whose dentition remained that of land animals.
While widely distributed, their preferred habitat seems to have been the
southern part of the Atlantic coast of the United States. In a certain dis-
trict in Alabama the vertebrae were originally so abundant as to attract
much popular attention and call forth legends of divers catastrophes.
240 GEOLOGY.
The non-placentals. — If the non-placentals of the northern conti-
nents had any kinship to the foregoing placentals, they failed to show
it by any special awakening in this time of marvelous placental evolu-
tion. In the basal Eocene beds there were somewhat more and larger
forms than in previous periods, and during the Eocene, early forms of
the opossum (Didelphys) appeared in both the Old and New World.
The opossum retained this wide distribution until the Miocene, when it
disappeared in Europe, but has remained in North and South America
to the present time.
The birds. — If compared with the singular record of the Cretaceous,
the deployment of the birds was very marked. So diverse forms as
ancestral gulls, herons, flamingoes, albatrosses, buzzards, falcons, eagles,
owls, woodcock, quails, plovers, and ostrich-like, flightless birds of great
size, with not a few forms of doubtful interpretation, had appeared.
The reptiles and amphibians. — One of the greatest contrasts in geo-
logical history is found in comparing the size, power, and multitude of
the Cretaceous land reptiles with those of the following Eocene. Of
the great saurian herd of the Mesozoic only a few forms lived over into
the very earliest Eocene epoch (Puerco), and these shortly became ex-
tinct, and with their extinction the saurians disappeared. True land
reptiles seem to have become rare. There were turtles on both land
and sea, and some of them attained a large size. There were crocodiles
which belonged about equally to land and water; also snakes, some of
which were python-like in form and attained large dimensions. The
amphibians were present beyond doubt, but, judging from the fossil
remains, they formed a very insignificant factor in the fauna.
The insect life. — When so much must be omitted, it is unwise to
dwell on changes that do not have significant bearings on historical
progress, and it may now be summarily remarked, on the authority of
Scudder,1 that there has been but little important change in the insect
world since the beginning of the Cenozoic era, almost no new orders
or even families having appeared, though the genera and species have
changed.
No very significant change is known in the molluscan or other forms
of terrestrial life not already noticed, nor in the fresh- water life.
1 Mon. XXI, U. S. Geol. Surv., 1893, p. 1.
THE EOCENE PERIOD.
241
The Marine Life.
The very name Eocene, founded upon the presence of a small per-
centage of living species, implies the stage reached by the marine inver-
tebrates. Not only were the existing orders, families, and genera
established, with some exceptions, but even the present species had
begun to appear. The changes that follow from this time on are valu-
able as criteria of correlation, climate, migration, and other elements
FIG. 433. — EOCENE FORAMINIFERA: a, Nodosaria bacillum Defrance; 6, N. communis
(d'Orbigny) ; c, Anomalina ammonoides (Reuss); d, Cristellaria gibba d'Orbigny;
e, C. radiata (Bornemann); /, g, and h, Globigerina bulloides d'Orbigny; i, Vagina-
Una legumen (Linne*); j, Discorbina turbo (d'Orbigny); k, Truncatulina lobatula
(Walker and Jacob); Z, Textularia subangulata d'Orbigny. Magnified 10 to 50
times. (Maryland Geological Survey.)
of the later history, but they do not record any further profound bio-
logical transformations. They stand in striking contrast with the radical
and rapid evolution of the placental mammalians.
Geologically, the most striking feature of the marine Eocene life
was the extraordinary abundance and size of the foraminifers. Mas-
sive beds of limestone in the Paris basin were largely made up of the
tests of Miliola. Other Eocene limestones were formed chiefly of Or-
bitolites, Orbitoides, Operculina, and Alveolina, while the nummulitic lime-
stone, whose wide range and great importance has already been indi-
u w
FIG. 434. — EOCENE MOLLUSCS: GASTROPODS: a, Fusus (?) interstriatus Heilprin;
6, Mitra potomacensis Clark and Martin; c, Pleurotoma tysoni Clark and Martin;
d, P. potomacensis Clark and Martin; e, Scala potomacensis Clark and Martin;
Tornatellcea bella Conrad; g, Turritella mortoni Conrad; h, Lunatia marylandica
Conrad. PELECYPODS: i, Glycymeris idoneus (Conrad); j, Dosiniopis lenticu-
laris (Rogers); k and I, Corbula aldrichi Meyer; m and n, Protocardia levis Conrad;
o and p, Venericardia marylandica Clark and Martin; q, Modiolus alabamensis
Aldrich; r, Leda parilis (Conrad); s, Lucina aquiana Clark; t, Crassatellites alce-
formis (Conrad) ; u, Ostrea comrressirostra Say; v, Nucula ovula Lea; w, Pecten
choctawensis Aldrich. (After Maryland Geological Survey.)
THE EOCENE PERIOD. 243
cated, was made up largely of the coin-like Nummulites, which lived in
prodigious abundance. The gastropods and pelecypods of modern types
became very prolific, while the cephalopods were markedly less impor-
tant than in the Cretaceous. The nautiloids were more abundant than
now, while the sepioids have left little record. The sea-urchins con-
tinued to be abundant, the corals had taken on the modern forms, and
the decapods were rising in importance.
The American Eocene faunas were rather pronouncedly provincial,
though there was a minor list of species of rather wide range, binding
the provinces together. This condition is assignable to the previous
restrictive movement, and to the fact that the shallow-water tract was
only a border belt and subject to much variation from point to point.
So true is this, that much difficulty is experienced in making a confident
correlation between the formations in different sections even along
the Atlantic and Gulf coasts. Much greater difficulties arise when
the regions are more widely separated. The variations are, however,
variations of detail, not of broad features that can be readily sketched.
For these, reference must be had to the paleontological reports on the
regions involved.1
THE OLIGOCENE EPOCH.
In North America. — As already stated, formations corresponding to
the Oligocene of Europe have not usually been differentiated, in North
America, from the Eocene below and the Miocene above. Recently,
however, the differentiation has been gaining ground, and may be jus-
tified for the reasons set forth on pages 194-5, or on paleontological
grounds, if it is desirable to make the classification for this country
conform as closely as possible with that of Europe.2
Certain beds along the Atlantic coast (Cooper River marl, and per-
*W. H. Dall, Tertiary Fauna of Florida, Trans. Wagner Free Inst. Sci., Vol. Ill,
Pts. 1-5, 1890-1900, finely illustrated; Bull. 141, U. S. Geol. Surv., 1896, and other
papers therein referred to. W. B. Clark, Md. Geol. Surv., Eocene volume, 1901,
finely illustrated, full bibliography, q.v. R. M. Bagg, Bull. 141, U. S. Geol. Surv.,
1896, Protozoa. A. Heilprin, Comp. Eocene Mollusca of Ulwich, Europe, Proc. Acad,
Nat. Sci. Phil., Vol. XXXI, 1879; Vol. XXXII, 1880; and Vol. XXXIII, 1881; Jour.
Acad. Nat. Sci. Phil, Vol. IX, 1884. T. W. Vaughn, Ccelenterata, Bull. 141, U. S.
Geol. Surv., 1896; Corals, Mon. XXXIX, U. S. Geol. Surv., 1900. T. W. Stanton.
Eocene of Pacific Coast, 17th Ann. Kept. U. S. Geol. Surv., Pt. I, 1895-6. Gilbert
D. Harris, Am. Pal. Bull., Vols. I and II.
2 For table of Oligocene formations, see Dall, 18th Ann. Kept. U. S. Geol. Surv.,
Pt. II.
244 GEOLOGY.
haps the Ashley River marl) formerly regarded as late Eocene
are now classed as Oligocene. The Ashley River marls of North and
South Carolina contain nodular phosphate of lime, locally in such quan-
tities as to be commerically valuable.1 The Chattahoochee and Chipola
beds of Florida are regarded as late Oligocene,2 and their fossils indicate
a climate warmer than that of the Miocene (Upper Miocene of the older
classification). Oligocene has been suspected on the Atlantic coast as
far north as New Jersey.3
The principal formations of the Gulf region which have been corre-
lated with the Oligocene of Europe are the Vicksburg (below) and
Grand Gulf formations4 of Alabama, Mississippi, and Louisiana, and
the Fayette 5 formation of Texas. The Vicksburg formation (Lower
Oligocene) is chiefly limestone, and is closely associated with the Eocene
(Jackson) limestone of the same region (p. 199). The Grand Gulf and
Fayette formations are made up of sediments which seem to have been
brought to the Gulf by the drainage of the present Mississippi basin,
and by that of the lesser basins bordering it on either hand. The land-
ward parts of these formations are non-marine, while the seaward parts
may be marine. The presence of gypsum in the Grand Gulf series
gives some suggestions of local conditions, and perhaps of climate. In
contrast with most other clastic formations of similar age along the
Atlantic seaboard, the Grand Gulf series contains firm sandstone, some
of which is even quartzitic.6
The Oligocene, especially the early Oligocene, is represented some-
what generously about the Caribbean Sea, where its association with
the Eocene is generally close,7 and its separation from the Miocene dis-
tinct. This is in keeping with the phenomena of the Gulf States. Lime-
stone is the dominant type of rock in the Antillean region.
1 Penrose Bull., 46, U. S. Geol. Surv.
2 Dall, op. cit.
3 Dall, Md. Geol. Surv., Miocene, p. CXLI.
4 Smith, Geol. Surv. of Ala., 1894. See also Dall, 18th Ann. Kept. U.S. Geol.
Surv., and Maury, A Comparison of the Oligocene of Western Europe and Southern
United States, Bull. Am. Pal., No. 15, p. 43.
5 Penrose, Geol. Surv. of Texas, 1st Ann. Kept.
6 The classification of the Grand Gulf formation is in dispute. Some of the beds
described under this name are probably younger than Oligocene. See Smith and
Aldrich, Science, New Series, Vol. 16, p. 836, and Vol. 18, p. 26.
7 Hill, Geology and Physical Geography of Jamaica, and Geological History of
the Isthmus of Panama and portions of Costa Rica. Bull. Mus. Comp. Zool., Vols.
XXVIII and XXXIV respectively.
THE EOCENE PERIOD.
245
The Oligocene is likewise represented among the terrestrial depos-
its of the western part of the continent. Following the Uinta stage
(p. 209) of the Eocene, physiographic and drainage relations were so
changed as to shift the sites of notable sedimentation. The next con-
siderable formation, the history of which is partially known, is the
White River formation, lying east of the northern Rockies. It occupies
an extensive area in northeastern Colorado, southeastern Wyoming,
western Nebraska (Brule and Chadron formations *), and South Dakota,
and it may extend southward even to Kansas.2 Clastic sediments pre-
FIG. 435. — Bad Land erosion in the Brule clay, near Scotts Bluff, western Nebraska.
(Barton, U. S. Geol. Surv.)
dominate in the White River series, and clay predominates over coarser
material, but beds and lenses of sandstone and conglomerate (or sand
and gravel) occur at various places, and there are thin beds and lenses
of limestone and some volcanic ash.
The origin of the White River beds has been the occasion of much
difference of opinion. They have usually been described as lacustrine,
but in recent years parts of them have been regarded as partly or
1 Darton, Camp Clarke, Scotts Bluff, Edgemont, and Oelrichs folios, U. S. Geol. Surv.
2 Adams, Am. Geol., Vol. 29, p. 303.
246
GEOLOGY.
wholly fluviatile,1 and even as eolian.2 The eolian origin has been
urged on the basis of the fossils, which are chiefly those of land animals
(land tortoises and mammals); but while much may be said for this
hypothesis as applied to parts of the formation, it does not seem appli-
cable to all of it, as the constitution of the beds shows. Gypsum, barite,
etc., in the series give some hint of the climatic conditions of the time.
In the light of present knowledge, it seems probable that all phases of
land aggradation, lacustrine, fluvial, and eolian, are represented in the
FIG. 436. — Chimney Rock, a detail in the Bad Lands of the White River country.
The base of the column is Brule clay. (Darton, U. S. Geol. Surv.)
series. The formation is said to have originally covered most of the
Black Hills region, and possibly all of it,3 for remnants are now found
up to elevations of more than 6000 feet, and the highest points of
the Hills are but little higher; but in so far as running water and wind
were concerned in its deposition, the present altitude and attitude
of the beds cannot be relied on as a measure of former extension or
later deformation.
In these and other comparable formations, well-defined bedding has
often been relied on as conclusive evidence of lacustrine origin; but it
should be remembered that eolian sand is often as distinctly stratified
as that which is deposited by water (Fig. 437). The stratification
1 Fraas, Science, Vol. 14, N. S., p. 212, holds that the earlier White River beds
were fluviatile, and that later ones were lacustrine.
2 Matthew, Am. Nat., Vol. XXXIII, p. 403, 1899.
3 Darton, 19th Ann. Rept. U. S. Geol. Surv., Pt. IV; 21st Ann. Rept. U. S. GeoL
Surv., II.
THE EOCENE PERIOD. 247
developed by the wind may often be distinguished from that developed
by water, but it is not clear that the distinction can always be made
where exposures are limited (Fig. 437).
In Colorado there was a small area of deposition in the South Park.
The beds (Florissant) deposited here consist largely of volcanic ash, and
are famous for the extraordinary number of insects which they contain.
Some of the John Day beds of Oregon,1 unconformable above the
FIG. 437. — Section of stratified dune sand (recent). South end of Lake Michigan.
(Bastin.)
Eocene (Clarno), are probably to be referred to the Oligocene. This
area of aggradation occupied but a few hundred square miles, but in
it sediments accumulated to a thickness which has been estimated at
several thousand feet. They consist, in considerable part, of volcanic
ash and tuff. The youngest of the John Day beds seem to be younger
than the White River beds, and perhaps should be classed as Miocene.
The John Day beds, Oligocene and later, appear to be largely of eolian
origin, but the upper part of the series contains fresh-water shells.2
1 Dall, 19th Ann. Rept. U. S. Geol. Surv.; Merriam, Jour. Geol., Vol. IX, pp. 71-2,
and Bull. Univ. of Cal., Vol. II, p. 270 et seq.
2 Merriam, Bull. Univ. of Cal., Vol. II, p. 270 et seq.
248 GEOLOGY.
The marine Oligocene is also represented in western Oregon l (Aturia
and Astoria beds), and the earliest Tertiary deposits of British Columbia
(non-marine) are now referred to the Oligocene.2 They contain some
coal, and antedate the Tertiary volcanic activity of the region.
Beds referred to the Oligocene are wide-spread in Alaska,3 where they
are sometimes carboniferous, and little disturbed. Here belongs the
thick Kenai series (said to be 10,000 feet) unconformable on Eocene.4
Certain fossiliferous beds of western Greenland seem to be of the same
age as the Kenai series.
Considerable geographic changes occurred during the Oligocene, or
at its close, especially in the Gulf and Carribbean regions.5 In both
regions, the Oligocene (early Oligocene) beds are commonly conforma-
ble on the Eocene and unconformable beneath the Miocene; and in
the latter, there was a notable deformation and increase of land during
the Oligocene or at its close.
The biological effects of the physical changes about the Gulf of
Mexico and the Carribbean Sea at about this time have already been
referred to.
FOREIGN.
Europe. — The Oligocene is more distinctly differentiated from the
Eocene in Europe than in most parts of America. Toward the close
of the Eocene, the epicontinental sea of northern Europe was excluded
from some areas which it had covered during that period, but the
changes which converted the Eocene areas of deposition into land were
probably slight, since after their occurrence considerable areas stood so
near sea-level that slight changes of altitude served to greatly restrict or
extend the epicontinental waters. How far the restriction of the sea
at the close of the Eocene was the result of surface warping, and how
far the result of the filling of shallow basins with sediment, is unknown.
At the beginning of the Oligocene period, the sea transgressed con-
siderable areas of Germany which had been land in the Eocene period.
1 Ball, op. cit., and Diller, 17th Ann. Kept. U. S. Geol. Surv.
2 Dawson, Science, March 15, 1901.
8 Schrader, Bull. G. S. A., Vol. 13, p. 248, and Brooks, p. 261.
4Dall, Trans. Wagner Free Inst., Vol. VI, 1903, p. 1548. See also Dall, 18th
Ann. Kept. U. S. Geol. Surv., Pt. II, and Spurr, Pt. III. The Kenai formation was
formerly classed as Eocene.
6 See references to the writings of Hill under Eocene.
THE EOCENE PERIOD.
249
At the time of its maximum extension (Middle Oligocene, Fig. 438), the
epicontinental sea of the period covered much of north Germany, and
the North Sea was connected with the Mediterranean, and extended to
southeastern Russia, and even to the Aral sea.1
The oldest Oligocene deposits of central and western Europe are
largely of terrestrial, fresh- and brackish- water origin. Local de-
FIG. 438. — Sketch-map of Europe in the Middle Oligocene. The shaded part shows
area of deposition. (After De Lapparent.)
posits of salt and gypsum show that there were local bodies of water of
excessive salinity.
In Britain, the Oligocene has but slight representation, being found
in one small area (Hampshire basin and Isle of Wight) only. As in
most other parts of Europe, the beds are partly marine and partly non-
marine. Some of the igneous rocks of the islands about north Scotland
may have dated from this period. The Oligocene is represented in the
Paris basin, partly by marine beds, partly by beds deposited in brack-
1 Kayser, Geologische Formationskunde, p. 479.
250 GEOLOGY.
ish water, and partly by beds of fresh-water origin. They lie uncon-
f ormably on older formations. They include sands, marls, arkoses, and
limestones, some of which are of fresh-water origin (snail-shells, caddis
worms, chara, etc.). Coal is also present, and the conifers and cypresses
which entered largely into its composition, together with the leaves of
the oak, laurel, cypress, fig, maple, birch, etc., which occur in the asso-
ciated clastic beds, give some notion of the aspect of the vegetation
and of the climate. Basaltic tuff is interbedded with the other forma-
tions, showing that the igneous activity of the region dates back to this
period. In central and eastern France, there is a bed of earth so full
of pisolitic grains of limonite as to be worked as iron ore. With it are
beds of limestone of fresh-water origin, sometimes containing so many
bones as to be a source of commercial phosphate of lime. These phos-
phate deposits sometimes (Quercy) occur in pockets and fissures in the
Jurassic rocks on which the Oligocene lies. The Oligocene of France
is divided into three principal series, the Tongrian (largely brackish)
below, the Stampian (chiefly marine) in the middle, and Aquitanian
(lacustrine) at the top.
In Belgium, the Tongrian is represented by marine beds below and
fluvio-marine above. The Middle series (Rupelian) is also partly marine
and partly non-marine, while the Upper is wanting.
The Oligocene of north Germany is mainly marine, yet there are
local beds of coal, fresh-water limestone, and other formations of non-
marine origin at various points. Conditions for land deposition indeed
seem to have been rather common about the borders of the areas which
the sea covered, especially early and late in the period. Locally, coal-
beds have extraordinary thickness (70 meters at Lutzendorf).
The Oligocene of southern Europe is chiefly marine, but in the upper
part of the series, lake and marsh deposits are not rare. In Italy it has
been estimated to have the extraordinary thickness of nearly 12,000
feet. The series is partly marine and partly terrestrial.
In Switzerland, the Oligocene is represented by the upper part of
the Flysch formation, which overlies the Lower Numrnulitic limestone
(p. 217), and by the lower part of the Molasse, which overlies thi Flysch.
The Flysch (5200 feet) is marine, while that part of the Molasse referred
to the Oligocene, is largely non-marine.
The Oligocene is also represented in the Vienna basin. The Aqui-
tanian stage is represented by marine and non-marine beds of sediment
THE EOCENE PERIOD. 251
and coal. Locally, the beds are now nearly vertical, and their disturb-
ance, accompanied by great outpourings of lava, seems to have begun
before the close of the Oligocene period. About the Dardanelles, the
Oligocene is non-marine, and coal-bearing.1 Farther south, the system
is not all marine. Among the non-marine formations is coal. The
fossils of southern Europe indicate some such climatic conditions as
those of the Mexican Gulf coast at the present time.
In Europe, as in North America, there were considerable igneous
eruptions during the Tertiary, and especially during the Oligocene. The
results are to be seen in Bohemia, where there is much igneous rock,
and in northern Ireland and western Scotland, where outpourings of
lava probably made great plateaus, of which some of the adjacent
islands are remnants, in Iceland, and in the Vienna basin. Between
eruptions, vegetation grew in the marshes and shallow lakes and over
the surface of the lava. The substance of this vegetation is locally
(Faroes, and Iceland) preserved in the form of coal between the lava-
beds. Some of the lakes of France seem to have been obliterated by
volcanic action.
Amber. — One of the peculiar formations found in the Lower Oligo-
cene is the amber of northern Germany. This is found principally in
the vicinity of Konigsberg. While amber in small quantities is found
in Sicily and a few other places, that of the Baltic region is more abun-
dant than that of any other part of the earth, so far as now known.
Amber is fossilized resin, apparently from certain varieties of coniferous
trees. Its original position in the Baltic region appears to be in certain
glauconitic beds of a clayey nature, but parts of this formation have
been worn by the waves, and the amber distributed. Some of that
which finds its way into commerce is picked up on the Baltic shore,
while some is taken from the beds in which it was originally entombed.
One of the interesting features of the amber is the fact that it fre-
quently contains insects. The insects seem to have alighted upon the
resin while it was soft, and to have become completely immersed in it,
and perfectly preserved. About 2000 species have been found thus
entombed. Subsequently, by the escape of its volatile portions, the
resin became hard, and was ultimately changed to amber. The amber
of the Baltic region was known to the Phoenicians, who appear to have
made trips to the region for it.
1 English, Q. J. G. S., 1904, p. 246.
252 GEOLOGY.
Bohnerz. — In southwestern Germany, and in parts of France and
Switzerland, there are peculiar and interesting mineral-spring deposits
(Bohnerz formation) yielding abundant fossils. This formation occurs
mainly near the outcrops of the White Jura. The mineral matter de-
posited from the springs incased many bones of mammalia, as well as
the bodies of other animals. On the decay of the organic matter, per-
fect molds of their forms were preserved. By being properly filled,
excellent casts even of delicate parts of flowers and insects are some-
times obtained. The name Bohnerz refers to bean-like concretions of
iron ore.
Other continents. — On other continents, the Oligocene has not been
generally differentiated. It is known in northern Africa, a part of the
Mediterranean province, and perhaps in Soudan.1 It is known in Pata-
gonia, where it is partly marine2 and partly non-marine, and it may
be widely distributed outside of Patagonia. The Oligocene of the An-
tillean and Central American regions has already been referred to. In
Panama, nummulitic limestone occurs.3 In New Zealand, igneous rock
is associated with the sedimentary beds of this epoch.
THE LIFE OF THE OLIGOCENE.
The vegetation. — The mixed evergreen and deciduous forests of the
Eocene merged into very similar ones in the Oligocene, particularly in
Europe. There palms continued to be abundant and varied, growing
even in north Germany, and being richly displayed in southern France
and northern Italy, especially in Liguria. They seem to have become
rare, however, in the United States, for in the Florissant sediments,
which are rich ir> plant fossils as well as insects, palms are barely repre-
sented. The Florissant fossils imply a return to a diversified angio-
sperm flora. Of 160 species identified by Lesquereux, 133 were angio-
sperms against 8 conifers, while 19 belonged to lower orders. The
conifers were represented by pines, yews, and sequoias which closely
resembled those of Europe, where they were relatively more abundant.
The variety of the angiosperms was great, and widely distributed
1 De Lapparent, La Geographie, Vol. XI, p. 1.
2 Hatcher. See references to this region under Eocene, and especially Geol. Mag.,
1902, p. 136.
3 Bertrand and Zurcher, Etude Ge"ologique sur 1'Isthme de Panama (Rev. in Geol.
Mag., 1903, p. 419).
THE EOCENE PERIOD. 253
through the several orders that are now found in the latitude of the
middle and southern States.
The land animals. — As already indicated, the Florissant beds are
phenomenally rich in fossil insects, and fishes also were abundant. Both
classes had a modern aspect of the middle temperate phase, but all the
species of insects, of which over 700 have been described by Scudder,1
are extinct. This seems to indicate that although the types had all
become modern, the species continued to evolve with relative rapidity.
In this respect the insects stand between the more slowly evolving marine
invertebrates and terrestrial plants on the one hand, and the more
rapidly evolving mammals on the other. The rapid development of the
mammals perhaps finds part of its explanation in their progressive
adaptation to the angiospermous vegetation. The mammals continued
their rapid evolution without interruption, and perhaps even with some
acceleration, assisted by the moderate extension of the land and good
migratory connections with Europe. The Carnivora proper came into
clear definition, and were represented in the White River beds by ances-
tral dogs (Daphcenus, Cynodictis, Cynodesmus), cats (Dinictis, Hoplo-
phoneus, Eusmilus), coons (Phlaocyori) , and weasels (Buncelurus) , while
some creodonts remained. The rodents were represented by squirrels
(Sciurus), beavers (Steneofiber) , pocket-gophers (Gymnoptychus) , rab-
bits (Palceolagus) , and mice (Eumys). Among the perissodactyls, the
rapidly developing horse family presented the forms Mesohippus and
Anchippus. There were also lophiodonts (Colodon), tapirs (Protapirus),
rhinoceroses (Leptaceratheriwn and Aceratherium) , and the related Hyra-
codon and Metamynodon, as well as gigantic titanotheres. The artio-
dactyls took on the extinct forms of Anthracotherium, Hyopotamus,
Elotherium, and of oreodons, as well as ancestral peccaries (Perchcerus,
Thinohyus), camels (Poebrotherium, Protomeryx), ruminants ^Lepto-
meryx, Hypertragulus, Hypisodus), and the singularly specialized horned
and tusked Protoceras, making the artiodactyls a very important group.
There were also insectivores (Ictops, Mesodectes), and marsupials referred
doubtfully to the genus Didelphys, the opossum.2 Many of the fore-
going were present also in Europe, where there were also shrews, moles,
1 The Tertiary Insects of North America, U. S. Geol. Surv. Ter., Vol. XIII, 1890;
Mon. XXI and XL, U. S. Geol. Surv., 1893 and 1900.
2 The classification of W. D. Matthew is here followed. Bull. Am. Mus. Nat.
Hist., Vol. XII, 1899, Art. III. pp. 19-75.
254 GEOLOGY.
muskrats, martens, civet cats, and various xiphodonts and anoplotheres,
as well as extinct forms.
The rhinoceros tribe had deployed into three notable branches, one
a true lowland form, ancestral in type to the existing family, another
aquatic (Metamynodori), and a third an upland, horse-like, running
form (Hyracodori). The Metamynodon was massive and stocky, like
the modern rhinoceros, but hornless, while the Hyracodon was light-
limbed and equine in many features, re-asserting the ancestral alliance
FIG. 439. — Titanotherium validum Marsh, photograph of a mounted specimen in the
Carnegie Museum, by Director Holland.
of the horses and rhinoceroses. The tribe had a cosmopolitan range
and was well represented in Europe.
The titanotheres were a massive erratic branch of the odd-toed
ungulates which arose late in the Eocene, reached their climax in the
Oligocene (White River), and then suddenly disappeared. They were
intermediate in proportions between the rhinoceros and the elephant,
and were distinguished by a long, depressed skull armed with a pair of
horns near the extremity of the nose, as were their kin the rhinoceroses,
but placed transversely, as in the ox (Fig. 439). They reached some
fourteen feet in length and ten in height. There were many variations
with age and sex, and several genera have been founded on these
THE EOCENE PERIOD.
255
variations (Brontops, Titanops, Megaceratops, Diconodvn, Haplacodon,
Symborodon, Menodus). They were American and apparently rather
local in distribution.
The elotheres were large pig-like animals, constituting a temporary,
highly specialized side branch of the even-toed ungulates, allied to the
Suidce. They appeared in North America in the White River stage,
and continued into the John Day (Miocene) stage, and were present
FIG. 440. — An interpretation of the general appearance of the elotheres, or giant
Eigs, of the White River epoch, drawn by Charles R. Knight under suggestions
•om Osborn and Scott, based on a skeleton in the Princeton Museum. (From
drawing in American Museum of Natural History. Copyrighted by the Museum.)
also in Europe. An interpretation of their general appearance by
Knight is shown in Fig. 440.
The Protoceras was remotely related to the deer family, and was
profusely and strangely horned, as though in diminutive mimicry of
the Dinocerata. There was, in the male, a blunt pair of protuberances
between the ears, a pair of basal cores between the eyes, and two large
prominences on the nose. The skull was only eight inches long, and
the animal about the size of a sheep. It was North American (White
256 GEOLOGY.
River) so far* as known, and may be regarded as foreshadowing the
deer (Cervidce). Being a highly specialized form, it had a short career,
as specialized forms usually do.
In a similar way the ruminants seem to have been introduced or
foreshadowed by the Tragulidce, the chevrotains, which are now repre-
sented in Farther Asia by a slender little ruminant, isolated and
scarcely known, the Tragulus, "the scarcely altered survivor of a
great tribe which flourished abundantly in Europe, and less so in North
FIG. 441. — Skull of a Protoceras-like animal (Syndyoceras cooki Barbour), recently
discovered in the Loup Fork beds of Nebraska. (Photo, by Barbour.)
America, before the typical and fully differentiated ruminants had made
their appearance." l
The oreodons were small animals, never exceeding the size of a
large dog, and are interesting chiefly as a primitive form that lived on
from the Eocene with little change, while its contemporaries were either
rising to climaxes and disappearing, or were evolving into modern and
more lasting forms. They seem to have been exclusively North Ameri-
can, and lived on till the late Miocene.
1 A. Smith Woodward, Vert. Pal., p. 360.
THE EOCENE PERIOD. 257
The marine life. — If the Vicksburg formation be regarded as Oligo-
cene, the general aspect of the Eocene sea life must be regarded as con-
tinuing into that period. Foraminiferal deposits (of Orbitoides in partic-
ular) are a notable feature, corresponding in phase with the nummulitic
formations of the late Eocene. With these were also many pelecypods
and gastropods, giving a decidedly molluscan cast to the fauna.
In the later stages of the American Oligocene, provincialism became
very pronounced, and the correlation of beds, even in the same province,
has been the subject of much difference of opinion.1 The foraminifers
having greatly declined, the fauna was overwhelmingly molluscan.
In Europe, provincialism was also very pronounced. Local and
transient faunas, shifting to meet the changing relations of sea and
land, were the characteristics of the time. No single great fauna like
the nummulitic of the Eocene appeared, but chiefly molluscan assem-
blages here and there, and now and again, as the shallow shifting phases
of the sea gave local embayments for temporary occupation.
1 Details can best be reached through Ball's papers, Tertiary Fauna of Florida,
Trans. Wagner Free Inst. of Sci., Vol. Ill, Pts. 1-6, 1890-1903; North Am. Ter.
Horizons, 18th Ann. Kept. U. S. Geol. Surv., 1898, Ft. II, and the references in these,
and Maury's Comparison of Oligocene of Western Europe and Southern U. S.f Bull.
Am. Pal. No. 15, Cornell Univ., 1902, and references contained.
CHAPTER XVII.
THE MIOCENE PERIOD.1
THE distribution of the Miocene beds (see map, Fig. 442) shows that
the geography of the North American continent during the Miocene
period was much the same as during the Eocene. The slight emergence
of the Atlantic and Gulf coastal belts after the Eocene (or early Oligo-
cene) was followed by a slight submergence of the same regions during
the Miocene. Locally, and perhaps generally, along the Atlantic coast,
the Miocene submergence exceeded the Eocene. The Mississippi em-
bayment of the Miocene was less extensive than that of the Eocene,
having been constricted by the partial filling or emergence of the lower
Mississippi basin. A portion of northern Florida, elevated after the
Eocene (or Oligocene, p. 215), constituted an island. On the Pacific
coast, the shore line was shifted westward somewhat beyond its present
position before the beginning of the Miocene, but as the period advanced,
the sea again encroached upon the land, finally reaching the foot of the
Sierras. At no time during the period, so far as known, did the sea
cover more than narrow borders of the present North American conti-
nent. The crustal movements which preceded the Miocene seem to
have closed such connection as there was between the Altantic and
the Pacific across Central America or the Isthmian region during the
Eocene.2 In the western interior, wide-spread terrestrial aggradation
of all phases continued, but the sites of principal deposition differed
somewhat from those of the preceding period.
The Atlantic coast. — The Miocene beds of the Atlantic coast are
generally unconformable on the Eocene (or Oligocene), but it does not
1 For general summary of literature on the Neocene (Miocene and Pliocene) prior
to 1892, see Ball and Harris, Bull. 84, U. S. Geol. Surv. The bibliography up to
1896 is found in the 18th Ann. Kept. U. S. Geol. Surv., Pt. II (Ball).
2 Hill, The Geological History of the Isthmus of Panama and Portions of Costa
Rica. Reviewed in Jour, of Geol., Vol. VI, p. 661.
258
THE MIOCENE PERIOD.
259
FIG. 442. — Map showing the distribution of the Miocene formations in North America.
Conventions as in preceding maps.
260 GEOLOGY.
appear that the sub-Miocene surface had been deeply eroded before the
deposition of the Miocene beds. The slight erosion was probably the
result of low altitude, rather than of a short .period of exposure, for a
considerable interval of time seems to have elapsed between the deposi-
tion of the Eocene and that of the Miocene of this province.
The northernmost exposure of the Miocene on the Atlantic coast is
on Martha's Vineyard. Between this point and Georgia it appears at
the surface interruptedly (Fig. 442). From New Jersey to North Car-
olina it fails only about the principal bays, where younger formations
conceal it. In its surface distribution it sustains the same relation to
the Eocene that the latter does to the Cretaceous, though it sometimes
overlaps the Eocene, completely concealing it. Like the other forma-
tions of the Coastal plain, the Miocene beds dip seaward and are con-
cealed by younger beds before the present shore line is reached. The
general relations are indicated by Fig. 380. Even in the belt where the
Miocene is mapped as appearing at the surface, it is often thinly covered
with younger deposits. The series originally extended inland far be-
yond its present border, as shown by numerous outliers. In New
Jersey,1 the Miocene series reaches a thickness of 700 feet; in Mary-
land,2 about 400 feet, and in North Carolina still less.
The Miocene of the Atlantic coast is for the most part made up of
unconsolidated beds of sand, clay, and shell marl. In places, diatoma-
ceous earths (variously known as Richmond earth [from Richmond,
Va.], Bermuda earth, Tripoli, infusorial earth, etc.) are found in beds
of such thickness (30 or 40 feet 3) as to be commercially valuable.
Much of the Miocene sand is remarkable for its even grain. It is
often aluminous, and has a remarkably soft feel, which has been de-
scribed as " fluffy/' It is often beautifully mottled with delicate colors,
and in many places contains small but beautifully smoothed quartz
pebbles. Locally, it is cemented into sandstone, and rarely the cemen-
tation has gone so far as to convert the sandstone into quartzite.
The Miocene beds of the Atlantic coast are generally grouped under
the name Chesapeake (or Yorktown). They were formerly regarded as
Upper Miocene, but the present tendency is to restrict the term Mio-
cene to the Chesapeake, the former Lower Miocene being classed as
1 Reports of the State Geologist of New Jersey, especially Report of 1892 (Clark).
'Clark, Maryland Geol. Surv., Vol. I; also volume on the Miocene, 1904.
3 Maryland Geol. Surv., vol. on Miocene, p. xxx.
THE MIOCENE PERIOD. 261
Oligocene. The fauna of the Chesapeake series has been interpreted to
indicate a climate somewhat cooler than that which had preceded, and
it has been conjectured that the change was the result of an uplift in
the latitude of South Carolina, the axis of the uplift extending seaward
sufficiently to divert the Gulf Stream far to the eastward, allowing the
cooler waters of the northern coast to affect the coast farther south
than before.1 This suggested explanation hardly seems adequate, and
the question may perhaps fairly be raised whether the Miocene fauna
of the Southern States does not represent the southward migration of a
northern fauna, rather than a notable change of climate. Such a
migration might perhaps take place irrespective of climatic change, for
the faunas of the north at this time do not appear to indicate any such
diversity of climate as now exists.
The Brandon formation. — Besides the marine Miocene beds along
the Atlantic coast, there are, at a few points farther inland, lignitic
beds which have been thought to belong to the Miocene. They appear
to represent accumulations of vegetal matter in marshes more or less
distant from the coast. The beds here referred to have been found in
Vermont, Pennsylvania, and Georgia, and have been described under
the name of the Brandon formation.2 With them are sometimes asso-
ciated beds of iron ore. The correlation of these various lignitic and
ferruginous beds with one another, and their reference to the Miocene,
cannot be regarded as beyond question.3
The Gulf coast. — The Miocene of the Gulf coast sustains the same
general relations to older formations as that of the Atlantic, except
that it is not known to be so generally unconformable on the beds
below. Excluding the beds classed as Oligocene, the system has but
slight thickness. In Florida, the limestone of the series has locally
been changed to lime phosphate.4 The alteration appears to have been
effected through organic matter, especially the animal excrements accu-
mulated about bird, seal, and perhaps other rookeries. The organic
matter furnished the phosphoric acid, which, carried down in solution,
changed the carbonate of lime to phosphate. The phosphate has been
extensively used as a fertilizer for soils. Similar phosphate deposits
are found in other places and in other formations.
1 Dall and Harris, op. cit.
2 Kept, of the State Geol. of Vt., 1903-4; and Clark, Bull. 83, U. S. Geol. Surv.
Dana assigns the Brandon formation to the Eocene, Manual of Geology, 4th ed.
3 Perkins, Bull. Geol. Soc. Am., Vol. XVI.
4 Fenrose, Bull. 46, U. S. Geol. Surv.
262 GEOLOGY.
Farther west the Miocene is represented by the Pascagoula forma-
tion (generally a greenish-blue clay) of Alabama * and adjacent States,
and by the Oakville beds on the coastal slope of Texas.2 In the latter
State there is little Miocene of marine origin exposed, but from borings
it is known that marine Miocene beds underlie some parts of the coastal
region. Such beds are said to be 1500 feet thick at Galveston. Non-
marine beds have extensive development in the northern part of Texas,
and will be referred to in connection with the other terrestrial forma-
tions of the period. Much of the oil of the Texas-Louisiana coastal
plain (Beaumont, Sour Lake, Saratoga, Jennings, etc.) comes from
dolomized limestones which overlie Eocene (or Oligocene) clays (Frio).
The limestones and associated clastic beds are probably Miocene.3
The Pacific coast. — The marine Miocene of the Pacific coast is
restricted to a relatively narrow belt. In California, the sea locally
invaded the central valley, but the position of the coast line appears to
have varied during the course of the period, as a result of crustal move-
ments, sedimentation, and the ejection of igneous matter.
Where the marine Miocene of California (the Monterey series) rests
on the Eocene (Tejon), the relation is generally one of unconformity,
and where the former overlaps the latter, it often rests on metamorphic
rocks. The Monterey series consists of shales, sandstone, and volcanic
debris, but varies notably from point to point. Its composition and
history in the San Luis region 4 may serve as an instructive illustration
of the marine Miocene of the Pacific coast (Fig. 444). Early in the
Miocene period, the sea transgressed most of the central and southern
parts of the Coast range, but before sedimentation had proceeded far,
volcanic activity began and a large amount of pyroclastic rock was
extruded from many vents. A notable feature of the sediments of this
stage is the abundance of diatomaceous matter with the volcanic ash.
In one place, fully a third of a 20 feet thick bed of fine ash, etc., is said
to be made up of diatoms. Later, volcanic activity subsided and lime-
stone deposition followed. Still later, organisms secreting silica re-
placed those secreting lime carbonate, and 4000 feet of shale, largely
1 Smith, Geol. Surv. of Ala., 1894. See also Reports Geol. Surv. of Texas;
Dall and Harris, loc. cit.
2 Bumble, Jour. Geol., Vol. II.
3 Hayes, Bull. 213, U. S. Geol. Surv., p. 346.
4 Fairbanks, San Luis folio, U. S. Geol. Surv.
THE MIOCENE PERIOD. 263
of organic origin, were deposited. Such thicknesses of such shale, if
their interpretation is correct, imply prodigious lapses of time. The
whole system here has a thickness of 5000 to 7000 feet.
In the vicinity of San Francisco, the Monterey series has a thick-
ness of more than 5000 feet, and is composed chiefly of sandstone, but
subordinately of bituminous shale.1 In the interpretation of the great
thickness, the considerations previously mentioned should be borne
in mind. The sections at other points would show notable variations
from those here given. One of the singular features of the Miocene
tuffs of the Santa Cruz mountains, near San Francisco, is the occurrence
of limestone dikes in them. These dikes are clastic, and the cal-
careous material of which they are composed is thought to have been
forced up into the tuff as ooze from below.2
The Miocene is one of the oil-producing horizons of California,
and the most important source of bitumen in that State.3
The Miocene of western California does not possess the simple struc-
ture which characterizes the corresponding beds along the Atlantic and
Gulf coasts. Instead of dipping gently to seaward, the strata have been
deformed in many places so as to stand at high angles (Figs. 443 and
444). Locally (Mount Diablo range), the beds have been folded, and
the folds overturned so that the Chico (p. 160) and Tejon (p. 201) series
overlie the Miocene.4 In the Santa Cruz mountains, the early Miocene
beds constitute a part of the metamorphic Pascadero series on which the
Later Miocene 5 rests unconf ormably. The Miocene beds are found in
some parts of the Coast Range 6 up to elevations of 2500 feet, and their
altitude, position, and stratigraphic relations give some indication of
the extent of the deformative movements which have affected this
region since the Miocene.
Farther north, considerable parts of western Oregon, including some
of the coastal ranges, were under water during the period, and Miocene
(Empire) bed» a few hundred feet thick, and containing volcanic ash,
1 Lawson, Science, N. S., Vol. 15, p. 416, 1902.
2 Haehl and Arnold, Proc. Am. Phil. Soc., Vol. XLIII, p. 16.
8 Eldridge, Bull. 213, U. S. Geol. Surv., p. 306.
4 Turner, The Geology of Mount Diablo, Bull. Geol. Soc. Am., Vol. 2, 1891.
8 Ashley, Jour. Geol., Vol. Ill, p. 434.
c Lawson, Bull. Dept. Geol., Univ. of Cal., No. 1, 1893, and No. 4, 1894; Lawson
and Palache, idem, Vol. II, p. 364; Ashley, Jour. Geol., Vol. Ill, p. 434; and Fair-
banks, Jour, of Geol., Vol. VI, p. 561.
264
GEOLOGY.
rest unconformably on the deformed and eroded Eocene l (Arago). In
British Columbia, there are both clastic and volcanic rocks referred to
this period.
FIG. 443. — Contorted beds of Monterey shale. Mouth of Vaquero Creek, Cal.
(Lippincott, U. S. Geol. Surv.)
Non-marine deposits. — While the sea occupied the southern part of
the great valley of California (as far north as the Marysville buttes)
during at least a part of the Miocene period, it seems not to have over-
spread the northern part, where contemporaneous deposits of estuarine,
FIG. 444. — Section showing the structure and relations of the Miocene system in
the San Luis Obispo region of southern California. Jsl, San Luis formation,
Jurassic; Nm, Monterey shale, Miocene; Nrt, rhyolite tuff; Np, Pismo formation,
Miocene (?); Npr, Paso Robles formation, Pliocene; Pal, recent alluvium, etc.
lacustrine, and probably subaerial origin (lone formation) were being
made. They consist of the common sorts of clastic sediments, with
some coal, iron, etc., and may be continuous, under the later beds
1 Diller, 17th Ann. Kept. U. S. Geol. Surv., Pt. I, pp. 475-6, and Coos Bay and
Port Orford folios, U. S. Geol. Surv.
THE MIOCENE PERIOD 265
of the great central valley, with the marine Miocene of western Cali-
fornia, though such connection cannot be affirmed. The lone forma-
tion, probably of late Miocene age,1 is now found at various altitudes
ranging up to 4000, or perhaps even to 7000 feet.2 This has been inter-
preted as a minimum measure of post-Miocene deformation, on the
assumption that the lone formation was all deposited at or below sea-
level. If part of it was fluvial, the above figures are not to be taken as
a measure of subsequent deformation.
East of the lone and the marine Miocene beds of California, aurif-
erous gravels,3 brought down by streams from the Sierras, were being
deposited in the lower courses of the valleys during at least the later
part of the Miocene period, and this deposition was continued after the
close of the period. These gravels seem to have been deposited on a
surface of slight relief, a surface which is interpreted to have been a
peneplain developed in the Sierran region in Cretaceous and Early
Tertiary (before mid-Miocene) times.4 The tilting of this plain toward
the end of the Miocene seems to have occasioned increased activity of
the streams in their upper courses, and the deposition of gravel below.
The Sierra mountains are thought to have been at least 4000 feet lower
than now when the auriferous gravels were deposited. From some of
the gravels of California, thought to be of Miocene age, human relics
have been reported,5 but there seems to be good reason for doubting
their authenticity.
During the later part of the period, sedimentary deposits, usu-
ally described as lacustrine, are thought to have extended from the
central valley of California northward into Oregon, and eastward between
the Sierra and the Klamath mountains, into northeastern California,
before volcanic extrusions had blocked the Lassen Peak pass. They
may connect with the Miocene beds of terrestrial origin known at
many points east of the Sierras between the 39th and 41st parallels.
Considering these non-marine deposits as lacustrine, it has been thought
1 Lindgren, Jour, of Geol., Vol. IV, p. 898.
2Diller, Jour, of Geol., Vol. II, p. 47.
3 Whitney, The Auriferous Gravels of the Sierra Nevada of Calif.; Turner, 14th
Ann. Kept. U. S. Geol. Surv., 1894; Lindgren, Jour. Geol., Vol. IV, 1896, pp. 881-906;
Diller, Jour, of Geol., Vol. II, pp. 32-54. See also folios of the Gold Belt of Calif.,
U. S. Geol. Surv.
4 Diller, Jour, of Geol., Vol. II, pp. 33-54.
5 Whitney, op. cit.
266 GEOLOGY.
that the waters of an extensive and irregular Miocene (Pah-Ute) 1
lake, or perhaps series of lakes, east of the Sierras, connected west-
ward with the waters in the valley of northern California,2 and per-
haps northward with the John Day basin 3 of Oregon. It is probable,
however, that much of this inland Miocene is of fluvial, pluvial, and
eolian origin. The sites of some of these deposits seem to have
been areas which were subject to erosion during the Eocene, and
then to have been so deformed as to become areas of deposition.
The terrestrial Miocene formations (the Truckee Miocene 4 of King)
are said to reach a thickness of 4000 feet (King) at some points in
the vicinity of the 40th parallel. In general, they are made up of
sandstones, conglomerates, volcanic debris, infusorial earths, and
fresh-water limestones, overlain by great thicknesses of volcanic tuffs.
The John Day series, the upper portion of which is perhaps Miocene,
is also thick (said to be 3000 or 4000 feet), and is made up largely
of volcanic ash and sand, much of which seems to be eolian.5 The
deformed and eroded John Day formation is overlain by lava, which
in turn is covered by a late Miocene formation (Mascall, perhaps
=Loup Fork). Miocene beds contemporaneous with the Miocene
of the John Day basin occur also in western Oregon and Washington.6
In the Mount Stuart region of the latter State, 1000 to 2000 feet of
basalt (Miocene) is overlain by 1000-1600 feet of sedimentary beds
(Ellensburg formation), largely fluvial7 (Fig. 445).
Other areas of deposition, some of them lakes, existed during the
Miocene in Nevada and Montana. In the southwestern part of Nevada,
the Miocene beds (Esmeralda formation) described as lacustrine, con-
sist of the usual sorts of clastic rocks, pyroclastic material, and work-
able coal, the latter showing that the formation is not altogether lacus-
trine. The formation also carries some sulphur. The remarkable
thickness of 14,800 feet (which may include Pliocene beds) is reported
1 King, Geol. Expl. of the 40th Parallel, Vol. I.
2 Diller, 14th Ann. Kept., U. S. Geol. Surv.
3 The earlier John Day beds were Eocene and Oligocene (Dall, loc. cit.), though
the later were Miocene.
4 Op. cit., pp. 412 and 458.
5Merriam, Jour. Geol., Vol. IX, p. 71, and Bull. Dept. of Geol., Univ. of Cal.,
Vol. II, p. 306.
6 Knowlton, Bull. 204, U. S. Geol. Surv.
7 Smith, G. O., Mount Stuart, Wash., folio, U. S. Geol. Surv.
THE MIOCENE PERIOD.
267
for this formation.1 With one exception, the fossil plants of the series
are new.2 In Montana, the Miocene sediments (Bozeman formation,
Fig. 446) are described as lacustrine, and are said to have a thick-
ness of nearly or quite 2000 feet. They consist of gravel (conglomer-
ate), sand, clay, limestone, and volcanic dust.3 In this region some
Ellensburg formation ,
1000-1500 feet
Yakima basalt,
1000-2000 feet
Taneum andesite
Manatash formation,
1000 feet ±
Easton schist
FIG. 445. — Columnar section showing the succession of formations in central
Washington. (G. O. Smith, U. S. Geol. Surv.)
of the cones built up by old hot springs, and subsequently buried by
clastic sediments, are still preserved.
Farther east, on the western part of the Great plains, the depo-
sition of the White River beds may have continued for a time after
the beginning of the Miocene, as indicated by the fauna of the upper-
most beds. Late in the Miocene period, aggradation seems to have
been renewed in the same general area, and the Loup Fork formation,
thin but extensive, was spread out over the western plains. In the
early part of this epoch (sometimes called the Deep River stage) the
deposits were of slight extent, being apparently restricted to several
1 Turner, Am. Geol, Vol. 29, p. 268, and 21st Ann. Kept. U. S. Geol. Surv., Pt. II.
2 Op. cit., p. 219.
3 Peale, Three Forks folio, U. S. Geol. Surv.
268
GEOLOGY.
Pleistocene \
Sphinx conglom-
erate
•?£
Livingston series
Laramie series •
Montana series
Colorado series
Dakota formation
Ellis formation
Quadrant forma-
tion
Madison limestone
FIG. 446. — Columnar
section showing the
succession of for-
mations in western
Montana. (Peale,
U. S. Geol. Surv.)
THE MIOCENE PERIOD. 269
small areas (lakes?) in southern and central Montana. Later the
area of deposition became more extensive/ and sediments were spread
widely over the area between South Dakota and Mexico. Though
the lacustrine and fluvial phases of the formation have not been com-
pletely differentiated, it appears that the latter were probably more
extensive than the former.1 To the north, the Loup Fork beds (prob-
ably the equivalents of the Arikaree and Gering of western Nebraska 2)
are often unconformable on the deformed and eroded White River
FIG. 447. — Court House and Jail Rocks. Buttes of the Arikaree (Miocene) for-
mation of western Nebraska. (Darton, U. S. Geol. Surv.)
beds, and like the latter have given rise to " bad-land " topography,
to striking monuments, buttes, etc. (Figs. 447-449). The Santa Fe
(fluvial) marls of New Mexico are correlated with the Loup Fork
beds.3 In Texas, beds of terrestrial sediments are wide-spread in
the Llano Estacado region, and have been described under the names
Loup Fork and Goodnight, though the Goodnight beds are sometimes
regarded as Pliocene.4
Terrestrial aggradation was doubtless in progress at many other
points in the west, though other considerable formations have not
been recognized or not differentiated.5
^ee Haworth, Univ. Geol. Surv. of Kan., Vol. II, p. 281.
2 Darton, U. S. Geol. Surv., 19th Ann., Pt. IV, and Camp Clarke and Scott's Bluff,
Neb. folios, U. S. Geol. Surv.
3 Johnson, D. W., Geology of the Cerillos Hills, N. M., Sch. of Mines Quarterly,
Vol. XXIV, p. 313, 1903. Bibliography given.
4 Scott, Introduction to Geology, p. 518.
6 The relations of the Miocene are shown (under the name of Neocene) on various
270
GEOLOGY.
Lake and other terrestrial deposits, largely of volcanic material,
are known north of the United States, especially in that part of
British Columbia l between the Coast and Gold ranges. The volcanic
centers seem to have been numerous, and along the eastern base of
FIG. 448. — Smokestack Rock. Conglomerate in the Arikaree formation of western
Nebraska. (Darton, U. S. Geol. Surv.)
the former range. Miocene deposits are known as far north as the
Francis River, and also on the Porcupine branch of the Yukon; but
erosion rather than deposition was the dominant process in Alaska,
so far as present data show.
Igneous activity during the Miocene. — The wide-spread igneous
activity which began with the close of the Cretaceous and continued,
folios of the U. S. Geol. Surv. Both sedimentary and igneous formations are repre^
sented.
1 Dawson, G. M., Trans. Royal Soc. of Canada, 1890.
THE MIOCENE PERIOD. 271
at least intermittently, through the Eocene, made itself felt also in
the Miocene, and perhaps reached its maximum toward the end of
that period. The frequent references in preceding pages to igneous
materials in the sedimentary formations of the system give some
idea of the extent of Miocene vulcanism. The eruptions were from
fissures as well as from volcanoes, and extensive sheets of lava as
I
FIG. 449. — Monument of Gering (Miocene) sandstone over Brule (Eocene) clay, western
Nebraska. (Barton, U. S. Geol. Surv.)
well as volcanic cones were formed, and intrusions as well as extru-
sions were of frequent occurrence. Evidences of volcanic activity
during this period are found in nearly or quite every State west of
the Rocky mountains. Among other centers of igneous activity may
be mentioned the basin of the Columbia l and the Yellowstone National
1 Landes, Wash. Geol. Surv., Vol. II, and Smith, G. O., Ellensburg folio, U. S.
Geol. Surv.
272
GEOLOGY.
Park,1 where evidences of Miocene volcanic activity are to be seen
on all hands. Locally,2 forests were buried by the volcanic ejecta,
FIG. 450.— Petrified tree-trunks, Yellowstone National Park.
(Iddings, U. S. Geol. Surv.)
and in favorable situations their trunks were petrified (Fig. 450).
Great areas of the sedimentary beds of the period are concealed by
*See western folios, U. S. Geol. Surv., notably the Yellowstone National Park
folio. Most of the folios showing Neocene formations show volcanic rocks of Neocene
age.
2 Yellowstone National Park folio.
THE MIOCENE PERIOD.
273
the lavas, but the extrusions were by no means confined to the areas
where Miocene sedimentation had been in progress.
While igneous activity has been in progress interruptedly since
the earliest known times, the record of few periods of geological his-
tory shows such extraordinary extrusions of lava as those of the Ter-
tiary. The exact stage of the Tertiary at which the great lava sheets
of the west were extruded has not been determined in all cases; but
the lavas of at least a considerable part of 200,000 or 300,000 square
miles of lava-covered country in the western part of the United States
FIG. 451. — Sections of petrified logs, near Holbrook, Ariz. Age of beds not known.
issued during the Miocene period, or during the time of crustal defor-
mation which brought it to a close.
The volcanic activity of the time was not restricted to the Cor-
dilleran system, but affected also the Antillean system of Central
America and the West Indies,1 and the Andean system of South
America.
Close of the Miocene. — During the Miocene, there appears to have
been more or less crustal movement throughout the Cordilleran region.
Slow warpings of the surface seem to have been in progress, while
1 Hill, Geology of Jamaica. Reviewed in Jour, of Geol., Vol. VII.
274 GEOLOGY.
faulting, vulcanism, and gradation all produced changes in the physi-
ography of the west. Locally, as in the Santa Cruz mountains of Cali-
fornia, there were pronounced orogenic movements 1 in the course
of the period, but toward its close crustal movements seem to have
been general. At this time pronounced deformative movements took
place in the coastal regions of Oregon 2 and California, tilting and
folding the Miocene and older formations. The principal growth
of the existing Coast ranges of both these States, and of the San Fer-
nando mountains of California are usually assigned to this time.3 The
orogenic movements in the Mount Diablo region have already been
referred to. The Cascade mountains of Washington also had notable
growth at this time.4
Similar movements appear to have been wide-spread throughout
the Cordilleran system, sometimes resulting in the deformation of
strata heretofore horizontal, but more commonly affecting formations
and areas which had suffered deformation at some earlier time. In
California, the Sierra peneplain, developed during the Cretaceous,
Eocene, and early Miocene periods, was deformed by being tilted up
on the east, increasing the grade of the westward flowing streams.
This deformation appears to have begun before the close of the Mio-
cene, and to have furnished the conditions necessary for the depo-
sition of the late Miocene auriferous gravels.5 Remnants of this old
plain are now 600 to 1900 feet above sea-level at the head of Sacra-
mento valley, and several thousand feet high in the main range. In
northern California, the deformation was such as to emphasize- the
central valley of the State. Since that time, too, there has been fault-
ing to the extent of 3000 feet on the east side of the northern Sierras.6
Deformation and faulting at the close of the Miocene seem also to
have been wide-spread and pronounced in the Great Basin region,7
and to have affected some parts of Colorado.8
1 Ashley, Jour. Geol., Vol. Ill, p. 434; Whitney, Geol. of California, I.
2 Diller, 17th Ann. Kept. U. S. Geol. Surv.
3 Ashley, op. cit.
4 Willis, Professional Paper 19, U. S. Geol. Surv.
6 Diller, Jour. Geol., Vol. II, p. 30, and Lindgren, Jour, of Geol., Vol. IV, p. 881
et seq.
6 Diller, 14th Ann. Kept., U. S. Geol. Surv.
7 King, op. cit., p. 414, and Dutton, op. cit., p. 226.
8 Walsenburg folio, U. S. Geol. Surv.
THE MIOCENE PERIOD. 275
In addition to the more distinctly deformative movements, body
movements and block movements resulting in the increased altitude
of the land throughout much of the western half of the continent
were in progress at this time. It appears to have been at about this
time that the plateau region of Arizona and southern Utah, a region
which prolonged erosion had reduced to a peneplain, was uplifted so
as to permit the beginning of the excavation of the Grand Canyon of
the Colorado.1 Other regions were depressed relative to their sur-
roundings, and the differentiation of levels was often by faulting along
planes of earlier displacement. It appears that the later part of the
Miocene was the time when the greater relief features of the rugged
west, as they now exist, were initiated. The great relief features
of earlier times, for such there had been, appear to have lost their
greatness before the end of the Miocene.
After the movements of the late Miocene had been accomplished,
it is probable that the western part of the continent had a topography
comparable, in its relief, to that of the present, though by no means
in correspondence with it. The details, and even many of the larger
features, of the present topography are of still later origin. Subsequent
changes have been the result of (1) deformation, largely without
notable folding, (2) faulting, (3) the extrusion of lava, and (4) exten-
sive degradation and aggradation, by running water, by ice, and by
wind.
Volcanic activity and faulting, both on a great scale, seem to have
attended the deformative movements of the closing stages of the Mio-
cene. The lavas on the plateaus north of the Grand Canyon have
been referred to the close of the Miocene, and the Tertiary volcanic
activity of the Basin region reached its maximum at this time.2
Though direct connection between intensity of movement and vigor
of volcanic activity has not been established, the connection of the
extensive igneous eruptions with the crustal warping and breaking,
can hardly be fortuitous. How far the one was cause and the other
effect, how far they were mutually cause and effect, and how far they
were effects of a common cause, are questions to which no decisive
answer can now be given.
1 Button, Mono. II, U. S. Geol. Surv.; see also Davis, Am. Jour. Sci., 4th series,
Vol. X, p. 250.
2 King, op. cit., pp. 414-415.
276 GEOLOGY.
In the eastern part of the continent, the geographic changes were
less considerable, though the Atlantic and Gulf regions seem to have
emerged, transferring the coast -line to some such position as it has
to-day. The island in northern Florida which came into existence
near the close of the Eocene was joined to the mainland at the end
of the Miocene, thus bringing the peninsula of Florida into existence.
The foregoing references of deformative movements to the close of
the Miocene are in harmony with prevailing classifications, but are not
in consonance with the principle of time-division previously set forth,
in which a dynamic movement is made the initiating event of a new
period. According to this principle, the deformative movements here
referred to the closing stage of the Miocene, should be transferred to
the opening stage of the Pliocene, or regarded as a transition to it.
Foreign.
Europe. — In Europe, the relations of sea and land were in general
much as in the Early Tertiary. The area of the sea was much restricted
in northern Europe, and perhaps more extended in the southern part
of the continent than it had been during the Oligocene. Non-marine
formations have much representation in this, as in most other post-
Paleozoic systems. Some of the non-marine formations are of brackish-
water origin, and some of fresh.
The marine beds occur chiefly along the Atlantic and Mediterra-
nean coasts. At the north, there was a great bay in the northwestern
part of Germany, including most of Holland and a part of Belgium,
but the beds deposited in it are mostly buried under a heavy body
of glacial drift. Elsewhere in Germany, except at the extreme south,
the somewhat wide-spread Miocene deposits are of non-marine origin.
They include coal and tuff, besides the commoner clastic sediments.
In southern Germany (Alpine region), the Miocene Molasse (marine
below and non-marine above) overlies the Oligocene portion of the
same series (p. 250), and is continued into Switzerland. The oceanic
connection of the waters in which the marine beds were deposited
was to the south. Thick conglomerates (3900-5900 feet) of Early
and Middle Miocene age are found along the north base of the Alps
(Rigi). Their materials came in part from formations which are still
visible, but in part from formations which do not now appear at the
THE MIOCENE PERIOD.
277
surface.1 Such thick beds of coarse sediment tell something of the
relief of the Alpine region at this time.
A shallow epicontinental sea covered a part of Belgium and France,
overspreading the plains of the Loire and Garonne. From the basin
of the latter, there may have been a sea connection with the Mediterra-
nean along the northern base of the Pyrenees. Parts of the Iberian
peninsula also, were submerged.
FIG. 452. — Sketch-map of Europe in the Miocene period (Helvetian). The continu-
ous lines are the areas of marine deposition; the broken lines areas of non-marine
deposits. (After De Lapparent.)
The sea covered much of southern Europe, sending an arm up
the valley of the Rhone as far as Mayence, but the water at the head
of this basin was changed from marine to brackish in the course of
the period. From this bay a strait ran eastward between the Alps
and the present Danube, and expanded in the basin of Vienna, one
of the most important areas of the Miocene system. An arm of the
1 Geikie, Text-book, 4th ed., p. 1270.
278 GEOLOGY.
sea extended thence through Moravia, and spread far and wide among
the islands of southeastern Europe, over the regions of the Black and
Caspian Seas.1 These great inland seas may be looked upon as the
relics of the Tertiary extension of the sea across southern Europe.
From the distribution of Miocene strata it is inferred that southern
Europe was an extensive archipelago, the plateau of Spain, parts of
Pyrenees, the Alps, and the Carpathian mountains, and portions of
adjacent lands, being islands. Malta and Sicily had probably not
appeared, as both are composed chiefly of marine Miocene formations.
The borders of the sea were marked by peninsular headlands giving
it notable irregularity. The strait of Gibraltar is thought to have
been closed, and southern Spain joined to Africa; but there were per-
haps straits across Spain, as across southern France, connecting the
Atlantic with the southern sea. To the east, the sea was expanded
far beyond the limits of the present Mediterranean, but without con-
nection with the Indian ocean. Though extensive areas of Europe
which are now land were then submerged, some areas which are now
submerged, e.g. the eastern part of the Adriatic, are thought to have
been land at that time.
Late in the Miocene period, there was a notable withdrawal of
the sea from the land, for many of the late Miocene deposits were laid
down in brackish and fresh waters, over marine beds referred to the
earlier part of the period. Thus the connection of the Vienna basin
with the Mediterranean sea, via the Rhone valley, was closed, or greatly
restricted, before the end of the period, and bodies of brackish and
fresh water came into existence where the sea had been. Well-defined
brackish-water faunas are developed in some places.
The Miocene formations include all the common sorts of sedimentary
rocks common to marine and non-marine deposits. The latter include
not a little limestone of fresh-water origin, made partly from the secre-
tions of algse. As was natural, too, under the conditions of sedimenta-
tion, the limestones of certain localities are made up almost wholly
of the secretions of a single type of life. Thus in the Vienna basin,
the limestone is made up in some places chiefly of coral, in others of
the shells of gastropods, in others of foraminiferal shells, in others
of the secretions of algaB, etc. The system has great development
in Italy, where it attains a thickness of nearly 6000 feet.
1 Geikie, Text-book of Geology, 4th ed., p. 1261.
THE MIOCENE PERIOD. 279
In spite of the wide sway of the southern sea of Europe, the Mio-
cene formations do not appear at the surface in great areas, though
found in all countries bordering the Mediterranean, both in Europe
and Africa. In most of these countries, the lower formations are of
marine origin, and the upper of brackish- or fresh- water origin.
About the Dardanelles, such beds contain petroleum and bitu-
FIG. 453. — Sketch-map showing area of non -marine deposits of the closing stage
(Sarmatian) of the Miocene. (After De Lapparent.)
men.1 In Africa, Miocene formations occur in Algeria and in Lower
Egypt, but not in Upper Egypt. They also occur in Syria, but not
in Arabia and Persia, showing that the water connection between
the Mediterranean and Indian ocean regions had come to an end.
The Gulf of Suez is thought to have been a Mediterranean bay at this
time.2
Close of the Miocene in Europe. — In Europe as in America con-
1 English, Q. J. G. S., 1904, pp. 255-260.
2 Hume, Geol. Mag., 1904, pp. 250-252.
280 GEOLOGY.
siderable disturbances occurred in the later part of the Miocene period,
and at its close. Before the end of the period the Alps had had a
period of growth, usually placed at the close of the Lower Miocene.
This date is fixed by the fact that the Lower Miocene beds on the
Alpine side of the Vienna basin are upturned, while the Upper Mio-
cene beds remain nearly horizontal. This is hardly to be regarded
as conclusive evidence that other mountains which were in process
of development during the Miocene had their principal growth at
the same time, for about other parts of the Vienna basin the Upper
Miocene and even later beds are deformed. The Apennines and other
mountains of southern Europe were also in development during the
later Miocene. In the Caucasus mountains, Miocene beds occur up
to heights of 2000 meters. It will be seen, therefore, that deformative
movements, resulting in the formation of great mountain systems,
were in progress in southern Europe, as well as in the western
part of America, during the later part of the Miocene period. Moun-
tain-making movements were apparently in progress in the Hima-
layan region also, and perhaps in other parts of Asia. As in America,
too, wide-spread movements which were not notably deformative
attended the growth of the mountains, with the result that the sea
which had overspread southern Europe was greatly restricted, though
not reduced to its present size. Igneous activity appears to have
attended the movements of the time, but not on so great a scale as
in North America.
Other continents. — The Miocene of Asia has not been generally
separated from the other Tertiary formations, but it is known to exist
in India 1 (Sind), Burma,2 and Japan,3 where the Tertiary (Miocene?)
contains petroleum and metaliferous veins, and in some other parts
of northeastern Asia. It is also found in Java, where it has a rich
fauna.4 The beds commonly referred to this system contain both
marine and terrestrial formations.
Australia is rich in Miocene beds, some of which are of marine,
some of lacustrine, and some of fluvial origin. Toward the end of
1 Oldham, Geol. of India.
2 Pal. India, New Series, I, 1901.
3 Geology of Japan, Imp. Geol. Surv., 1902.
4 Martin, Die Tertiarschichten auf Java, 1879-80. See also Zeitschr. d. d. geol.
Gesell., 1900.
THE MIOCENE PERIOD. 281
the period, sheets of basalt were poured out over the sedimentary
formations. In New Zealand l also, the system is well developed on
both islands. It includes both marine and non-marine beds, and
among the latter, coal. The fauna is distinguished by the great size
of some of its molluscan shells. Both the flora and fauna have a
tropical aspect. The fruit of the palm has been found as far south
as latitude 45°. Igneous rocks are associated with the sedimentary.
The beds are found up to heights of 2500 to 4000 feet, giving some
clue to the extent of post-Miocene crustal deformation. Miocene is
found, with other Tertiary formations, in Borneo and in the Philip-
pines.2
In South America, Miocene beds probably occur on the western
coast, and are known to have extensive development on the eastern
plains of the southern part of the continent,3 where the distinction
between the Upper Oligocene and the Miocene is not sharp. The
lower part of the Oligocene-Miocene series (Patagonian beds) is marine,
while the upper part (Santa Cruz) is of fresh-water origin. A strik-
ing feature of the faunas of this region is their similarity to the Mio-
cene and later faunas of Australia and New Zealand. This relation-
ship has caused speculation as to an Antarctic continent connecting
these regions.4 Miocene is probably present also in northern Chili.5
Arctic latitudes and climate. — Miocene beds are somewhat widely
distributed in high latitudes. They are found in Spitzbergen (Lat. 78°),
in Greenland (Lat. 70°), in Grinnell Land (Lat. 81° 45'), and at other
points in the Arctic regions. In all these places the formations seem
to have been largely of terrestrial origin, and the fossil floras indicate
a warm temperate climate. Forty-six of the 137 species of plants
found in North Greenland 6 (Lat. 70° and less), including species of
sequoia and magnolia, are also found in central Europe. The floras
of Spitzbergen and Grinnell Land were hardly less luxuriant, or less
1 Geikie, Text-book of Geol., 4th ed., p. 1274 from Murray and Hector).
2 Becker, 21st Ann. Kept., U. S. Geol. Surv., Pt. Ill, p. 548 et seq.
3 Hatcher, Sedimentary Rocks of Southern Patagonia, Am. Jour, of Science,
Vol. IX, 1900; and Ortmann, Princeton Univ. Repts. of Expedition to Patagonia,
Vol. IV, Pt. II.
4 Ortmann, op. cit.
6M6ricke and Steinmann, N. Jahrbuch f. Min., etc., Beilagebd., X, p. 533, 1896.
6 Heer, Flora Fossilis Arctica, 1868-83. Also Q. J. G. S., 1878, p. 66, and Nor-
denskjold, Geol. Mag., 1876, p. 257.
282 GEOLOGY.
strongly in contrast with the floras of the same region at the present
time. Curiously enough the Miocene plants of Alaska, Kamschatka,
and Japan indicate a climate cooler than that of the higher latitudes.
It seems probable that this apparent discrepancy is the result of imper-
fect correlation, the fossils indicating these inharmonious conditions
not being contemporaneous. If this is the explanation of the apparent
anomaly, the subtropical floras of the high latitudes are probably
earlier than the other floras with which they have been compared.
In any case, the existence of warm temperate conditions in such high
latitudes in such recent times is remarkable, especially when it is
remembered that extensive ice sheets were soon (geologically speak-
ing) to affect not only these regions, but regions much farther south.
It is worthy of emphasis that throughout all lands where the Mio-
cene system is known, terrestrial aggradation seems to have been one
of the leading features of the period. Terrestrial aggradation implies
still greater terrestrial degradation, and relatively great relief. The
necessary relief seems to have been the result of the crustal move-
ments which brought the Eocene period to a close.
THE LIFE OF THE MIOCENE.
The Land Plants.
The flora of the Miocene in the mid-latitudes differed from that
of the Oligocene chiefly in the gradual disappearance of the character-
istic subtropical types, and in an increased proportion of deciduous
forms, especially of those that are now present in the same regions.
This is particularly true of North America, where the flora came to
resemble that which to-day lives in somewhat lower latitudes, and is
indeed its successor. The flora of Europe bore a similar " American "
aspect, but this it has not retained in an equal degree. This is attributed
by Zeiller to the barrier to southern migration interposed by the Med-
iterranean during the ice invasions of Pleistocene times, a barrier which
prevented the plants from escaping southward, and led to the destruc-
tion of many species which subsequent migration from other regions did
not restore. In Europe there were also, in the early part of the
period, not a few species now found in India and Australia, giving,
as in the previous period, an " Australian " sub-aspect to the flora.
A very important feature in North America was an increase in the
THE MIOCENE PERIOD. 283
grasses, which in turn influenced the evolution of the mammals in the
lines already pointed out.
How far the gradual removal to the south of the forms now regarded
as tropical or subtropical, and the concentration at the north of the
forms that now characterize those latitudes, was the result of a natural
differentiation and segregation of the previously mixed forms, and
how far the result of a progressive differentiation of climate, it is per-
haps unsafe to say; it has usually been attributed to the latter. It
has been customary to interpret the climatic implications of the Ter-
tiary floras by the southern forms, such as the palms, magnolias, figs,
etc., and to ignore the northern forms, poplars, willows, etc. For
this there are apparently some good reasons, but it is not clear that
they are conclusive.
According to Heer,1 there were Miocene forests in high latitudes
(Nova Zembla, Spitzbergen, Iceland, Greenland, Grinnell Land, Banks
Land, the mouth of the Mackenzie, and Alaska) which contained pines,
cypresses, birches, maples, walnuts, poplars, elms, oaks, lindens, wil-
lows, hazels, and even magnolias and tulip-trees. Question has how-
ever been raised as to the period to which these belong, and as the areas
are all isolated, stratigraphical tracing is impracticable. It seems
not impossible that they were Eocene. When, as in a case like
this, there is ground to suspect that faunas and floras are forced by
climatic changes to migrate rather rapidly in latitude, the basis of
correlation by fossils is disturbed, for the existence of the same faunas
and floras in different latitudes does not prove contemporaneity; it
may only mean successive occupancy by forced migration. Exact
correlations therefore become very difficult. But the occurrence of
these plants in so high latitudes in either the Eocene or Miocene is
sufficiently remarkable.
The Land Animals.
The earlier fauna. — The early Miocene of North America (John
Day epoch) was separated by a long interval from the late Miocene
(Loup Fork epoch) and this gave a marked distinctness to the faunas
of the two epochs. The earlier resembled the Oligocene (White River)
fauna in general aspect, but most of the mammalian genera, and nearly
1 Flora Fossilis Arctica, Vol. I, p. 161.
284 GEOLOGY.
all the species were new and more modern in type. The primitive
carnivores, the creodonts, had disappeared and their places were taken
by true carnivores. These were chiefly of the cat and dog families,
with a few mustelines. Three of the short-lived side branches of the
odd-toed ungulates had dropped away, the titanotheres, the upland
running rhinoceros, and the aquatic rhinoceros, reducing the perisso-
dactyls essentially to their three persistent lines, the horse, the tapir,
and the lowland rhinoceros. A straggling lophiodont and an occa-
sional doubtful form represented the last serious efforts of the odd-
toed tribe in side lines. It seems to have found its place by its pre-
vious trials, and thereafter developed consistently along its three most
successful lines. A similar remark may be made of the even-toed
branch from which the anthracotheres, protocerases, xiphodonts
(European), caBnotheres, and anoplotheres disappeared, and the evolu-
tion settled down into the modern lines. The elotheres lingered through
the early epoch, and the oreodons through the whole period, being
very abundant during the early part. Peccaries and camels flourished,
and the rodents were well deployed, including squirrels, beavers,
gophers, rabbits, and lemmings.
The later fauna, the elephants. — In the late Miocene (Loup Fork)
the fauna was broader in type. The most notable addition in North
America was the proboscidians. It is now practically demonstrated 1
that the elephant family originated in Africa, migrated later to Eurasia,
thence to North America and later to South America. The elephants
reached North America in the late Miocene, and South America in the
Pliocene. They were first known in Europe in the lowest Miocene (Bur-
digalian of France), while primitive proboscidians lived in Egypt at least
as early as the Middle Eocene. This confirms the anticipations of Steh-
lin,2 Osborn,3 and others, that the point of dispersion of the Probos-
cidea and some other groups would be found in Africa. The Eocene
forms thus far found in Egypt are Moeritherium, Barytherium, Palceo-
mastodon, and perhaps Arsinoitherium, an aberrant type of doubtful
1 C. W. Andrews and Hugh J. L. Beadnell, New Mammals from the Upper Eocene
of Egypt, Geol. Surv. of Egypt, 1902; C. W. Andrews, Evolution of Proboscidea,
Phil. Trans., Roy. Soc. Lond., 1903.
2Ueber die Geschichte des Suiden-Gebisses, II. Thiel; Abh. d. Schweiz, Pal. Gesell.,
Vol. 27, 1900, p. 477.
3 Correlation between Tertiary Mammal Horizons of Europe and America, Ann.
N. Y. Acad. Sci., Vol. XIII, 1900, pp. 1-72.
THE MIOCENE PERIOD. 285
classification. The forms found in Eurasia in the Miocene are Dino-
therium and Tetrabelodon; those found in the Upper Miocene in North
America are Tetrabelodon and Dibelodon. The Dinotherium, which
was distinguished by downward curved tusks in the lower jaw, seems
never to have reached America. This, together with the simplicity
of the teeth of the American Tetrabelodon, has suggested that the latter
may have reached America by some other than the European route,
perhaps via eastern Asia.
FIG. 454. — A Miocene Mastodon, Tetrabelodon angustidens Cuvier. (Restoration by
Gaudry.)
The immigration of the ruminants. — Much more important in
ulterior results was the immigration of the modern ruminants. Cer-
tain branches of the ruminants had been represented previously by
the Tragulidce, Camelidce, and perhaps other groups now extinct, but
the great ruminant group that later formed so important a part of
the fauna does not seem to have been derived from these, but to have
immigrated from Eurasia. They are first recorded in the Loup Fork
beds. The first immigrants belonged to the deer and ox families.
The earliest known deer (not including Protoceras) are first known in
Europe. They were hornless, as are their surviving relatives in Asia,
the musk-deer and the Chinese water-deer.1 By the middle of the
Miocene period certain male forms had acquired small two-pronged
deciduous antlers, fixed on long bone pedicles. About the close of
lVert. Pal., Woodward, p. 365.
286 GEOLOGY.
the period, three or four prongs were added, and in the Pliocene the
antlers were variously branched and the pedicles were shortened to
insignificance, as in most living deer. This historical evolution of
the antlers is reproduced in the individual history of the modern male
deer. Born hornless, he acquires in successive years the single, the
bifurcate, and the more and more complexly branched antlers that
mark the history of the race. It was in the bifurcating stage that
the deer appeared in America, its antlers being simple and small, but
variable. The skeletons imply lightness and speed, but a less com-
plete adaptation to celerity than was attained later.
There is some doubt as to the precise stage to which the remains
of bison found in Nebraska and Kansas are to be assigned. They
have usually been referred to the Lower Pliocene, but Matthew assigns
them to the Upper Miocene, while Williston refers them to the early
Pleistocene.1 The earliest known bisons on the Eurasian continent
have been found in the Siwalik formation of India, which is regarded
as Lower Pliocene.
The camels, oreodons, and peccaries. — Besides the new families
of artiodactyls, three of the previous ones continued to flourish, the
camels, the oreodons, and the peccaries. Fifteen species of camels
have been identified from the Loup Fork formation, belonging to
the genera Procamelus, Protoldbis, Miolabis, Oxydactylus, and Pli-
auchenia. The more primitive genera of the White River and John
Day epochs had disappeared. The more robust Procamelus and its
allies of the Loup Fork epoch quite distinctly foreshadowed the true
camels which were later to go to Asia, while the Pliauchenia fore-
shadowed the llamas, which were later to go to South America; but
the whole family seems yet to have been confined to North America.
The oreodons, though destined to become extinct at the close of the
period, were represented by 18 American species. They appear thus
not to have dwindled away but to have gone out suddenly, in the
geological sense, not unlikely from the attacks of some new carnivore.
They appear never to have migrated from North America. The pec-
caries do not seem to have been specially abundant.
The evolution of the horse. — It was a great epoch in the evolution of
the hoTse,Anchippus,Protohippus, Pliohippus(Merychippus), Hipparion,
1 Bull. Am. Mus. Nat. Hist., XII, 1899, p. 74.
THE MIOCENE PERIOD. 287
and other genera flourished and deployed into forty or more species.
They were still three-toed, but the two lateral toes were much reduced
and did not usually touch the ground, while the central one was
strengthened and bore all the weight. A large group of structural
features were being modified, concurrently with the feet, to fit the
FIG. 455. — An American Miocene Camel, Oxydactylus longipes Peterson, from the
Loup Fork beds of Nebraska. (After Peterson.)
evolving horse to the open dry plains and their grassy food (Fig. 456).
The elimination of the side toes, the lengthening of the limbs, the
change of the joints to the " pulley- wheel " type, the concentration
of the limb muscles near the body to reduce the weight of the parts
most moved, and the consolidation of the leg bones, were modifica-
tions in the interest of combined speed and strength. A corresponding
elongation of head and neck was necessary to reach the ground. The
front teeth were reduced to chisel-like, cropping forms, somewhat
resembling those of the rodents, while the molars evolved a tortuous
distribution of the enamel so flanked by dentine and cement that
the differences of wear gave rise to ridges of enamel suited to grinding,
and protected against breaking by supporting dentine and cement
on either side. The teeth were also gradually elongated to provide
288
GEOLOGY.
1
THE MIOCENE PERIOD. 289
for the great wear caused by the dry silicious grasses.1 It is probably
as safe to infer a development of dry grassy plains from this evolu-
tion of the horse, as to infer climatic and topographic conditions from
plants and other organic adaptations, and hence it is probably safe
to interpret the western " basins " as lodgment plains of the subaerial
rather than of the strictly lacustrine type, so far as the nature of the
deposits leaves the question open.
The tapirs and rhinoceroses. — The tapirs were but slightly repre-
sented, but the rhinoceroses, though the running and swimming branches
had dropped away, were a prominent feature in the fauna. The Ameri-
can species were still mainly hornless (Aceratherium) , slight indica-
tions of horns appearing in a single genus (Diceratherium) . Two-
horned species, however, appeared during the period in Europe.
The carnivores. — The carnivores were abundant, and had assumed
forms referred with some doubt to the living genera Canis, Felis, Mustela,
and Putorius. The Canidce embraced numerous wolves and foxes,
the Felidce-, panther-like animals and saber-toothed cats, the Mustelidce,
weasel-like and otter-like forms, and an ancestral coon is recorded.
The genera of the Loup Fork horizon were nearly all different from
those of the John Day horizon, which indicates rapid evolution. In
Europe, in addition to these four families, the bear, civet, and hyena
families were represented, thus including the seven existing families
of carnivores.
The rodents were represented much as in the earlier epoch.
Neither the insectivores nor the primates appear in the North American
record. The development of the plains which favored the horses,
deer, and cattle, was obviously unfavorable to the lemuroids.
The primates in the Old World. — In the Old World, the true apes,
Oreopithecus and Dryopithecus, appeared. The former was a rather
large annectant form uniting some of the characters of the apes and
the monkeys; the latter was a generalized type related to the chim-
panzee and gorilla, and about as large as the former. It is the view of
some paleontologists that the ancestral branch of the Hominidce must
have diverged from its relatives at least as early as this, since, for ana-
tomical reasons, it could not well have been derived from the Simiidce,
1 An excellent recent statement of the evolution of the horse, admirably illustrated,
is given by Matthew. Sup. to Am. Mus. Jour., Vol. Ill, No. I, Jan., 1903, Guide
Leaflet No. 9.
290 GEOLOGY.
and this family had already become differentiated; but on the deriva-
tion of the Hominidce the record throws no immediate light.
The marsupials. — The marsupials were but meagerly represented in
America or Europe, and the period witnessed the last appearance of
the opossum in Europe. The state of the marsupials and monotremes
in Australia, where they came into dominant importance later, is
undetermined.
The lower vertebrates. — Little of moment is recorded relative to
the lower vertebrates. Not much is known of American Miocene
birds, but their advancement in later stages implies that they con-
tinued their evolution with measurable rapidity, and this is supported
by the European evidence. The reptiles had very generally assumed
the modern forms, and were represented by turtles, snakes, and croco-
diles. The amphibians came again to notice in the form of a large
salamander, whose remains, found at Oeningen, Switzerland, formerly
attained an unworthy celebrity from false identification as a human
skeleton, and from the application of the pretentious designation,
Homo diluvii testis.
Summary. — A general view of the American Miocene fauna shows
that the great order of ungulates took precedence in evolution and
that both the odd- and even-toed branches participated actively.
Closely following these in importance, and dependent on them for the
conditions of their evolution, came the carnivores, while the rodents
occupied a median place, and the insectivores and lemuroids notably
declined.
The European record bears a similar general interpretation, with
the ungulates somewhat less pronouncedly in the lead, the carnivores
somewhat better deployed, and the proboscidians a conspicuous factor,
while the important evolution of the higher primates seems to have
been wholly confined to the Old World.
The Marine Life.
Provincialism dominant. — The pronounced provincialism that had
been inaugurated in the Oligocene epoch continued throughout the
remainder of the Cenozoic era. There was some amelioration during
the Miocene, but it was not marked. No essential relief was possible
so long as the shallow seas remained mere bordering tracts, as in North
America, or mere bays and straits, as in Europe. Even the border
THE MIOCENE PERIOD. 291
tracts that were geographically continuous, though narrow, show
signs of having been cut into biological sections by special interrupting
agencies. Such barriers had perhaps been operative in certain pro-
vincial periods before, but they were not so well recorded as now. The
land area being large, great rivers joined the coast here and there and
poured volumes of fresh and muddy waters across the shore belt, doubt-
less forming barriers to some species, though probably not to others.
The warpings of the crust probably projected peninsulas and submarine
ridges out upon and perhaps across the continental shelf, and these
were not only barriers in themselves . but supplemented their own influ-
ence by directing the courses of the coast currents. As differences
of climate in different latitudes had apparently been developed, cold
and warm currents were probably more active than in the previous
times of more uniform climate, and their shif tings had still graver
effects upon the faunas. So too, the lower temperatures in the northern
shore tracts of the Atlantic and Pacific shut off these tracts from serving
longer as migratory routes for the warm-water species, and this further
tended to intensify the provincial nature of the shallow-water faunas.
According to Dall,1 the Chesapeake Miocene was ushered in by
a marked faunal change due to a cold northern current driving out
or destroying the previous warm-water fauna of the region, and bringing
with it a cold-water fauna. There was a complete change of species,
and even some genera were displaced. The fauna retained, however,
a general molluscan aspect. Both the bivalves and the univalves
gave proof of better adaptability to the vicissitudes of the coastal
tracts than most other forms, and whether warm or cold waters pre-
vailed, held their dominance. Figs. 457 and 458 show a few of the
characteristic types. Compared with the Eocene group, Fig. 434, the
resemblances will be found, by the untechnical observer, more striking
than the differences.
Notwithstanding the provincializing agencies, there were many
close correspondences between the faunas of the western and the eastern
sides of the Atlantic, probably due partly to intermigration and partly
to parallel evolution. These correspondences have been set forth by
Dall in the following quotation:2
" In a general comparison of the European and American Miocene we find,
among other things which may be cited as parallelisms: in land vertebrates
1 Papers previously cited. 2 Md. Geol. Surv., Miocene volume, 1904, pp. cli-cliii.
292
GEOLOGY.
FIG. 457. — MIOCENE PELECYPODS: a and b, Area (Scapharca) stamin:a Say; c and d
Corbula idonea Conrad; e, Crass .tellites marylandicus (Conrad); /, Phacoides (Pseu-
domiliha) foremani (Conrad); g, Tellina (Angulus) producta Conrad; h, Leda con-
centrica (Say) ; i, Modiolus dalli Glenn; /, Astarte thomasii Conrad; k, Ensis directus
(Conrad); I, Spisula (Hemimactra) marylandica Dall; m, Isocardia markoci Conrad;
n, Cardium (Cerastodermd) leptopleurum Conrad; o, Pecten (Chlamys) madisonius
Say; p, Venus ducatelli Conrad; q, Ostrea carolinensis Conrad. (After Maryland
Geological Survey.)
THE MIOCENE PERIOD.
293
FIG. 458. — MIOCENE GASTROPODS (one Scaphopod).
294 GEOLOGY.
the Sansans and Deep River mammals, and among cetaceans the presence of
Squalodon, Balcena, Priscodelphinus and other dolphins. Among the sharks
may be cited Carcharodon megalodon, Hemipristis serra and Notidanus primi-
genius. Oxyrhina, Carcharias, Galeocerdo and variaus rays were abundant in
the sea bordering the western continent during this period.
" In Europe corals are rare except at the south; in Maryland Astrohelia
and Septastrea represent the group, the waters of Chesapeake time in this
region having been too cold for reef corals and too shallow for the deep-sea
forms.
" The Echinoids of the Miocene are as a rule few in species and profuse in
individuals; Clypeaster, Scutella, and Spatangus being the most prominent of
European, Amphidetus and Scutella of American forms.
" Among the Vermes Spirorbis is conspicuous, and Balanus among the Crusta-
ceans.
" Among the Foraminifera numrnulites are absent, and, in America, Orbi-
toides. Amphistegina, Ehrenbergia, Cassidulina, and Ellipsoidina are prominent in
Europe, Polystomella, Planorbulina, Rotalia, Textularia, Polymorphina, and
Uvigerina in America. Lithothamnion is a common fossil in the marine
Miocene of both continents.
" There are left the Mollusca, which we may examine a little more closely.
" Cephalopods are rare in the Miocene. The Aturia, which in America does
not persist beyond the middle of the Oligocene, in Europe is said to linger a
little longer. Nautilus is known from both the east and west coasts of America
in the Miocene.
" In America, among the Toxoglossate gastropods, Terebra (represented
by species of the subgenera Hastula and Oxymeris) is notable, there are many
Pleurotomoids, the cones are few and coarse, Cancellaria is represented by a
notable number of species. The same remarks apply almost equally to the
North German Miocene.
" American Rhachiglossa are numerous. A species of Oliva and one of Sca-
phella at least appear in both America and North Germany. Busycon in the former
region is represented by Tuicla in the latter. Fusus is more abundant in Europe
than in America, but the peculiarly characteristic Miocene subgenus of Chryso-
domus, Ecphora, is represented in North Germany by a form almost interme-
diate between the American E. quadricostata and Chrysodomus decemcostatus.
Ancilla, Murex, Purpura, and Tritia are conspicuous in the Miocene faunas of
EXPLANATION OF FIG. 458. — a, Turritella variabilis Conrad; b, Scala sayana Dall;
c, Nassa marylandica Martin; d, Terebra unilineata Conrad; e, Solarium trilineatum
Conrad; /, Cancellaria alternate Conrad; g, Surcula biscatenaria Conrad; h,
Calliostoma philanthropus (Conrad); i, Actceon shilohensis Whitfield; i, Oliva
litterata Lamarck; k, Retusa (Cylichnina) conulus (Deshayes); I, Conus diluvianus
Green; m, Polynices (Neverita) duplicatus (Say); n, Fissuridea alticosta (Conrad);
ot F. griscomi (Conrad); p, Xenophora conchyliophora (Born); q, Crepidula for-
nicata (Linn6); r, Fulgar spiniger (Conrad) var.; s, Ecphora quadricostata (Say);
t, Siphonalia marylandica, Martin; u, Ilyanassa (?) (Paranassa) porcina (Say).
SCAPHOPOD: v, Dentalium attenuatum Say. (After Maryland Geological Survey.)
THE MIOCENE PERIOD. 295
Europe, Ptychosalpinx, Ilyanassa, and Tritia in America. The Melanopsis of
Europe is paralleled by the Bulliopsis of America.
" Among the Tsenioglossa, Turritella is conspicuous in both continents;
a form of Cassis (Cassidaria or Sconsia) is equally present. Cyprcea is more
numerous in Europe, but represented in both regions; Pyrula occurs in both,
more abundantly in Europe ; as do the various types of Tritoniidce, such as Septa,
Lotorium, and Ranella. Pyrazus is more abundant in Europe and the Calyp-
tmidce in America.
" Among the Rhipidoglossa, Calliostoma is more representative in America
and Gibbula in Europe.
" Turning to the bivalves we find an equally noticeable parallelism. In Europe
Glycymeris, Barbatia, and Scapharca are very characteristic, as they are in America.
Ostrea is large and numerous, large Pectens occur, though the latter are per-
haps less characteristic of the Miocene than in America.
" The conspicuous place of the Cardiums in our Miocene is hardly filled by
the species in the European faunas, where also we find a notable number of Iso-
cardia. Mactra in Europe is represented by Spisula in America. Panopea
is about equally conspicuous in both, Cardita more so in Europe, Astarte in America.
Corbula and Saxicava are equally common to both regions. The very character-
istic Mytiloconcha occurs in both. A host of uncharacteristic forms, such as
Nuculidoe, Abra, Tellina, Ensis, Macrocallista, Timoclea, Lima, Phacoides, etc.,
are common to both, but in Europe Venerupis, Paphia, Eastonia, Lutraria,
Cardilia, Pecchiolia, Congeria, and Adacna are found with no American Miocene
equivalents. Crassatellites, Crassinella, Agriopoma, Rangia, Mulinia, Melina,
occupy the same, or nearly the same, position on the western continent, where
the giant species of Venus make their first appearance.
" In a general way, allowing for local peculiarities, the Miocene fauna of
North Germany compares well and agrees closely with that of Maryland, while
the Mediterranean Miocene finds a closer analogue in the more tropical fauna
of the Duplin beds of the Carolinas. We have not in America any equivalent,
faunally, of the Congeria beds of the Upper Miocene of eastern Europe."
CHAPTER XVIII.
THE PLIOCENE PERIOD.
THE most distinguishing formational feature of the Pliocene is
its aggradation deposits.1 This is a consequence (1) of the excep-
tional deformations which took place during the period, and just before
its beginning, and (2) of the recency of the deposition which has saved
the formations, to a large extent, from removal. There is little doubt
that similar deposits were made in similar amounts during and after
other periods of comparable deformation, but they have been largely
swept away by subsequent erosion. The Pliocene deposits will suffer
the same fate if the continent remains quiescent until another base-
leveling, like that of the Cretaceous, is accomplished.
Simple and obvious as the method of terrestrial aggradation is,
and illustrated in a small way in almost every tract of diversified topog-
raphy, its results are less clearly recognized than those of most other
phases of sedimentation, and their identification, correlation, and pre-
cise interpretation are attended with difficulties much beyond those
which attend typical marine, lacustrine, and fluviatile deposits. Of
the major examples of Pliocene deposits of this class, those formed
in the intermontane basins, abundantly exemplified in the Great basin,
are the most obvious and unquestioned, though largely misinterpreted
as lacustrine deposits. Lacustrine deposits are, however, present
and extensive in this region.
1 In its broadest sense, all sedimentary formations on land or under water are
aggradational, but deposits under seas and lakes have their own distinctive terms,
marine and lacustrine, and deposits made in the channels or on the flood plains of
rivers have their designations, fluvial or fluviatile, and alluvial. The term aggra-
dation is coming into use to designate a group of complex deposits that take place
on land partly by overburdened rivers, but quite largely by temporary streamlets,
slope-wash, " sheet-wash," and miscellaneous agencies that remove material from
uplands and deposit it on flat lands, and it is in this sense that it is employed here.
296
THE PLIOCENE PERIOD.
297
PIG. 459. — Map showing the distribution of the better known parts of the Pliocene
system. The conventions are as in other maps, except that the area of the Lafay-
ette, along the Atlantic and Gulf coasts, is marked by vertical dashes. This for-
mation is doubtless more wide-spread than the map shows, as indicated in the
text. Relatively little of the exposed Pliocene is marine.
298 GEOLOGY.
Over areas much greater than those occupied by lakes in Pliocene
times, and over tracts which never formed parts of definite flood plains,
broad aprons of detritus brought from the higher slopes are accumu-
lating now, and similar accumulations were quite surely making in
Pliocene times. Such accumulations are most considerable on the
flanks of mountain ranges where precipitous slopes join plains of
low gradient. Particularly is this the case where the climate is sub-
arid, and the rain falls in sudden and copious showers, largely
concentrated on the mountain heights, while the thirsty plains below,
covered with porous wash, quickly drink up the sudden mountain
floods and strand the detritus which they brought down in their
swift descent. Most of the western mountains of America are flanked
by such deposits, which sometimes spread far out upon the adjacent
plains. A portion of these deposits are of Pliocene age, and a por-
tion are still younger. In basins occupied by lakes, these su.baerial
sediments merge into lacustrine deposits, and, as a consequence of
the fluctuations of the lakes, are more or less interstratified with them.
They also merge so insensibly into true flood-plain deposits that they
cannot be systematically separated from them; nor should they be,
since they are of the same essential nature. If slopes are suitable,
deposits on plains free from standing water are likely to be more extensive
than lacustrine deposits, for the whole plain is then open to subaerial
aggradation free from competitive lacustrine catchment. It is prob-
ably safe to affirm that Pliocene deposits of this type lie concealed
beneath later accumulations of a similar sort in nearly all the large
basins, and at the bases of nearly all the steep slopes in the western
mountain region. Positive proof of their presence is difficult, both
because of the difficulty of distinguishing them from later deposits
physically, and because of the paucity of fossils. The Pliocene deposits
of this sort which have been identified are probably but a small frac-
tion of all that exist.
On the whole it would appear that erosion was the dominant
process hi the Cordilleran region during this period, but that a not
inconsiderable part of the eroded material was left in basins and
valleys and on plains, not far from its source.
Among the formations which have been described, usually as lacustrine,
from the area west of the Rocky mountains, are those of the Great basin1 and
1 King, Geol. Expl. of the 40th Parallel, Vol. I, pp. 525-543.
THE PLIOCENE PERIOD. 299
certain parts of Colorado (North Park, North Platte, etc.). In some cases their
areas are large, though their boundaries are undetermined. They have been
assigned thicknesses ranging up to 1400 feet, and they contain much volcanic
debris. They are said to be unconformable on the Miocene, which they over-
lap in all directions. The later auriferous gravels 1 of California (Fig. 460)
already referred to under the Miocene, belong to this class. Their deposition,
begun in the Miocene, was continued into the Pliocene, and probably even
into the succeeding period. Deposits of similar origin probably abound
throughout the western mountains, but, except where the latter are of glacial
Na
FIG. 460. — Section showing auriferous gravels, Ng, overlain by rhyolite tuff, Nr, and
andesite, Na. Length of section 1£ miles. (Lindgren, Nevada City, Cal. Special
folio, U. S. Geol. Surv.)
or fluvio-glacial origin, they have few characteristics which distinguish them
from later deposits.
Sedimentation (Rattlesnake beds) appears to have continued during the
Pliocene in the John Day basin,2 where the aggregate thickness of the Tertiary
beds is said to exceed 10,000 feet.3 Pliocene beds are also reported from
Idaho (Idaho formation), where they overlie the Payette (Eocene) formation
unconformably,4 from New Mexico,5 Arizona,6 and Mexico7 (Sonora). Non-
marine sedimentary beds are also said to be of common occurrence in the
southern Coast ranges of California,8 and are reported from the coastal plain of
northern Alaska, where the sequoia grew 9 in latitude 70°, or thereabout.
East of the Rocky mountains, on the border of the Great plains,
deposits of this class have been noted at many points, but a demon-
strative interpretation is as yet generally lacking. Some of them
have been referred to the Pleistocene, but many so referred are prob-
ably older. In many places these formations show by their constitution
that the source of their material was in the western mountains. In
1 See references to Auriferous Gravels under the Miocene, p. 274.
2Merriam, Bull. Dept. of Geol., Univ. of Cal., Vol. II, p. 312.
3 Merriam, Bull. Geol. Soc. of Am., Vol. XII, p. 496.
4 Lindgren and Drake, Nampa and Silver City folios, U. S. Geol. Surv.
5 Reagan, Am. Geol., Vol. XXXI, p. 84.
8 Blake, Sci., Vol. XV, N. S., p. 413, and Dumble, Am. Inst. Min. Eng., Vol. XXXI,
p. 696.
7 Dumble, Trans. Am. Inst. Min. Eng., Vol. XXXI, p. 696, XXIX, p. 691, 125.
8 Fairbanks, Jour, of Geol., Vol. VI, p. 565.
9 Schrader, Bull. Geol. Soc. of Am., Vol. XIII, p. 249.
300 GEOLOGY.
some situations the gravels have been shifted repeatedly, always farther
from the mountains and to lower levels, with the result that they
now constitute a series of deposits, of somewhat different ages, rather
than a single formation which can be assigned to a definite epoch.
Here are to be classed, probably, the Nussbaum formation of Colorado,1
and equivalent but unnamed bodies of gravel in Wyoming, Montana, and
New Mexico, and, farther from the mountains, the Goodnight beds of Texas,
unconformable on the Loup Fork, the Uvalde 2 and Blanco formations of the
same state, the latter consisting of sands, clays, diatomaceous earths and some
limestone 3 (Reynosa, non-marine), as well as gravel. Gravels of similar age
occur in Kansas 4 (often cemented into " mortar beds ") and western Ne-
braska 5 (Ogalalla formation).
Formations of this class have been even less well recognized in the
Old World, but from the descriptions of the Indian geologists, it seems
probable that the great Siwalik formation, a derivative from the Hima-
layas in their rising stage, belongs to this class. The enormous and
abrupt elevation of the Himalayas, in close juxtaposition to the great
Indo-Ganges plain, presented extraordinarily favorable conditions for
such a foot-plain deposit, and the Siwalik formation may come to
be the classic example of aggradational deposition.
The juxtaposition of precipitous heights and flat plains is not
the sole condition for aggradational formations. A less sharp differ-
entiation between feeding and lodgment grounds will suffice, when
adjustments are favorable.
In the Mississippi basin, far from the Rocky mountains on the
west and the Appalachians on the east, there are patches of gravel on
various hills and ridges, which are interpreted as the dissevered rem-
nants of a once more or less continuous mantle of gravel and other
river detritus. Data are not at hand for the definite correlation of
these gravels, and they may not all be of the same age. They are
not older than late Cretaceous, and are older than the glacial drift.
The source of this material, which is almost wholly quartz, quartzite,
and chert, is partly local, but apparently more largely from the north.
1 Walsenburg, Spanish Peaks and Pueblo folios, U. S. Geol. Surv.
2 Vaughan, Uvalde folio, U. S. Geol. Surv.
"Penrose, 1st Ann. Kept. Geol. Surv. of Tex., 1890, p. 63, and Dumble, Jour, of
Geol., Vol. II, p. 562.
4 Haworth, Geol. Surv. of the Univ. of Kans., Vol. II.
5 Darton, 19th Ann. Kept. U. S. Geol. Surv., Pt. IV.
THE PLIOCENE PERIOD. 301
The similarity of these gravels to the Lafayette farther south sug-
gests their correlation with that formation. Perhaps a better view
is that they are the older part of the complex series of river deposits,
shifted repeatedly to lower levels, and nearer the sea, until the main
part of the series is now near the coast, while only meager remnants
remain in the sites of original deposition. The farther these remnants
are from the low coast -plain the smaller they are and the greater their
altitude, and if the above interpretation be correct, the greater their
age. In other words, the remnants become larger, lie at lower levels,
and are presumably younger, to the southward, where they seem to
grade down to the more continuous Lafayette formation soon to be
described.
The patches of gravel here referred to are found in Minnesota,1
Wisconsin,2 Iowa, Illinois,3 Arkansas,4 Indiana,3 Kentucky, and Ten-
nessee. The leading topographic features of the Mississippi basin
have been developed since the deposition of these gravels, for their
northern remnants are on the crests of the highest lands within the
areas where they occur.
Reference was made to the phase of deposition here set forth in
connection with the Potomac series (p. 112), and the phenomena
seem to have been repeated in the same region, in much the same
way, in the Pliocene, giving rise to the Lafayette formation, known
earlier in the Mississippi basin as the Orange sands. This formation
has been, and still is, the occasion of so much difference of opinion
that it merits special consideration. It should be said, in prudence
and fairness, that the interpretation here given it is not unchallenged,
and the alternative views will be indicated later.
The Lafayette Formation.5
The Lafayette formation has an extensive distribution between the
Appalachians and the Atlantic, and in the Mississippi basin, and is repre-
1 24th Ann. Rept. Minn. Geol. Surv., p. xxv.
2 Jour, of Geol., Vol. Ill, p. 655.
3 Bull. Geol. Soc. of Am., Vol. Ill, p. 183; see also references given in this paper.
4 Geol. Surv. of Arkansas, Report on Crowley's Ridge, and also Am. Jour. Sci.,
Vol. XLI, 1891, pp. 359-377, and Vol. XLII, p. 252.
5 The fullest account of this formation as a whole is that of McGee in the Twelfth
Annual Report of the U. S. Geological Survey. References to other accounts of
the formation in special localities, often under other names, are as follows: Safford,
302 GEOLOGY.
sented, if our interpretation be correct, in the valleys west of the Appa-
lachians. An analogous formation is found on the Coastal plain of
Texas, and, by inference at least, this is associated with analogous
deposits on the Great plains, and through them with the intermontane
deposits of the west, already mentioned. The term Lafayette has
been usually applied only to the formation on the slope between the
Appalachians and the Atlantic, to that in the Mississippi basin below
the junction of the Ohio, and to the Texan tract. The formation
thus limited has been estimated to have an area of from 200,000 to
250,000 square miles. It lies like a blanket over the eroded edges
of all the older formations of the region, from the pre-Cambrian to
the Miocene. It extends inland from the coast up to varying altitudes.
In Mississippi, its landward edge is said to reach an elevation of 500
or 600 feet; in Tennessee, 800 feet; at Austin, Texas, 500 feet, and
near the Rio Grande, 1000 feet1; but on the Atlantic slope, the ele-
vation is generally less.
At its mountaihward edge, ragged belts of the Lafayette forma-
tion follow the valleys up into the mountains, and unless our identifi-
cations be in error, they reach back through the gaps, where they
are locally interrupted, into the intermontane valleys. Between the
valley phases, its mountainward edge recedes and is ragged, and
has not yet been carefully mapped. At its seaward margin, the for-
mation is more or less completely concealed by younger beds. It is
not to be doubted that the Lafayette formation or its equivalent passes
out to sea beneath these younger beds. Indeed, there is some reason to
believe that at some points it is replaced within the present land -area,
by marine beds, as such a formation is very liable to be where the
plain on which it was deposited slopes gently to the sea. But such
marine deposits as can be correlated, even hypothetically, with the
Geology of Tenn. (Bluff Gravels), and Am. Jour. Sci.,' Vol. XXXVII, 1864; Hilgard,
Agriculture and Geology of Mississippi, 1860, and Am. Jour. Sci., Vol. XLI, 1866, and
Vol. IV, 1872; Loughridge, Kentucky Geological Survey; Jackson Purchase Region,
1888; Geology of Illinois, Vol. I, pp. 417 and 447; Salisbury and Call, Geol. Surv.
of Ark., Report on Crowley's Ridge, 1889; Hill, Am. Geol., Vol. VII, 1891, p. 368,
and (with Vaughan) Uvalde formation of Texas, 18th Ann. Rept. U. S. Geol. Surv.,
Pt. II, p. 560; Dumble (Blanco Formation of Texas), Jour. Geol., Vol. II, 1894, p. 560;
Smith, E. A., and Johnson, L. C., Geol. Surv. of Ala., 1894. For synonyms of the
formation, see Am. Geol., Vol. VIII, 1891, pp 129-131, and Bull. 84, U. S. Geol.
Surv., p. 328.
1 McGee, loc. cit.
THE PLIOCENE PERIOD. 303
Lafayette, probably correspond to but a limited part of the complex
formation whose elements are many and intricate. On the west side
of the Appalachians, the formation seems to be essentially continu-
ous in the Tennessee valley as far north as Knoxville at least.
The base on which the Lafayette formation rests is of slight relief,
and appears to have been either in an advanced stage of erosion when
the Lafayette formation was deposited, or too low to have become
notably rough as a result of erosion. In addition to the relief deter-
mined by erosion, the surface had a gentle slope to seaward.
Thickness. — Like most sedimentary formations, the Lafayette is
variable in thickness. In general, it thickens seaward, and thins in
the opposite direction; but at any given distance from the sea, it is
thicker in the valleys which affected the surface on which it was
deposited, and thinner on the divides between them. The thickness
ranges from nothing to 200 feet or more. Sections of 20 or 30 feet
are common, and thicknesses greater than 50 feet are rare.
Constitution. — The Lafayette is a very heterogeneous formation,
composed of gravel (and occasionally bowlders two or three feet in
diameter), sand, silt, and clay, variously related to one another. It
may be said to be both heterogeneous and homogeneous; that is,
there is considerable variation in its material within short dis-
tances, and but little more in great ones. In the lower Mississippi
valley, where the formation first attracted serious attention, and whence
the name is derived (Lafayette County, Miss.), it is predominantly of
sand and gravel, the coarser phases along drainage lines. In these tracts
it has usually the distinctive characteristics of fluvial sands and
gravels. The formation assumes a different phase over a broad tract
of the uplands east of the Mississippi and away from valleys generally.
In such situations it is composed largely of silt and clay. Some of
the clay is of exceedingly fine texture, and from such clay there are
various gradations into silt and sand. The formation is largely com-
posed of the insoluble residue of the older formations farther up the
slope on which the mantle lies, chert and quartz pebbles making up
the gravels, and other insoluble matter the fine constituents.1 These
constituents replace one another at short intervals and in various
ways, and no systematic succession is observable. Lens-like masses
1Hilgard long ago pointed out (Am. Jour. Sci., Vol. IV, p. 266, 1872) that the
formation contains almost nothing which can be oxidized or readily dissolved.
304 GEOLOGY.
are not uncommon. Irregular stratification is the rule, but some
portions are not bedded or laminated. Among such parts are singular
lenses of sand which suggest an eolian origin. While assortment
generally prevails, it is very often irregular and imperfect. A singular
pebble-earth that finds its analogue in subaerial and flood-plain deposits
is common, but, so far as we know, has no representative in marine
and lacustrine deposits.
Color. — The coloration of the formation is significant, ranging
from brick-red through various pinks, purples, oranges, and yellows to
white. The color is more irregular than the composition, bands,
blotches, and mottlings diversifying the structural units. Where an
ancient, if not the original, surface of the Lafayette is preserved by
an overlying deposit, such as the loess, there is often a highly colored,
sub-surface zone, analogous to the sub-surface coloration of the later
deposits which cover it. This coloration is partly inherent in the
material, but more largely the result of a thin coating of red ferric
oxide enveloping the grains. Its significance is thought to lie in its
suggestion of the climatic conditions which accompanied or followed
the deposition of the formation, conditions under which the de posi-
tional action of sub-surface waters was greater than their leaching
effects. Such conditions are assignable to effective dry seasons.
Partial removal of the formation. — Something has already been
said with reference to the general distribution of the Lafayette for-
mation, but it is not to be understood that it occurs everywhere within
the area specified. As a result of stream erosion the formation is
discontinuous. Over considerable areas, it caps divides, but is absent
from the valleys between them. In many places its remnants are
best preserved where the substratum is resistant rock, and less preva-
lent where the substratum is rock which is easily eroded.1
In Mississippi 2 and Alabama 3 a considerable belt underlain by
the Selma (Rotten) limestone is essentially free from the formation;
so also is the belt underlain by the Jackson or White limestone, and
the belt underlain by parts of the Lower Eocene 4 (Black Bluff, or
1 Smith, Geology of Alabama, 1894.
2Hilgard, Agr. and Geol. of Miss., 1860, p. 5.
3 Smith, Geol. Surv of Ala., 1894, p. 68.
4 McGee also points out the absence or meagerness of the formation over cal-
careous sub- terranes, 12th Ann. Rept. U. S. Geol. Surv.
THE PLIOCENE PERIOD. 305
Sucarnoche of Alabama, Flat woods of Mississippi). These belts are
now rather lower than their surroundings, and the absence of the
Lafayette from them has usually been assigned to subsequent erosion.
An alternative interpretation, however, seems possible, in the light of
present knowledge. The areas from which the Lafayette is absent are
mainly underlain by calcareous formations. If they were divides when
the Lafayette was deposited, and if in later time they have suffered
more by solution than adjacent formations have by erosion, the present
relations might have been brought about.
Fossils. — Fossils are rare in the known parts of the formation.
In the unquestioned and representative portions of the Lafayette,
all are of land plants and animals (except, of course, the fossils derived
from earlier formations). The formation is much dissected and un-
usually open to observation, so that the observed rarity of fossils must
be taken as really representative. As already remarked, it is probable
that seaward equivalents of the Lafayette contain marine fossils.
Genesis. — As here interpreted, the Lafayette formation belongs
to an important class, long neglected, but now coming into recognition,
whose distinctive features are less critically familiar than those of
marine, lacustrine, and typical fluviatile formations. The preferred
interpretation is as follows: After the Cretaceous base-leveling of the
region, brought out by Davis,1 Hayes,2 Campbell, and others, the Appa-
lachian tract was bowed up and a new stage of degradation inaugu-
rated. During the long Eocene period, a partial peneplaning of
the less resistant tracts was accomplished. This was slightly inter-
rupted by the Oligocence deformation, and the streams mildly reju-
venated in the more responsive tracts. During the Miocene period,
base-leveling was resumed, abetted by relative subsidence along shore,
as indicated by the landward spread of the Miocene sea, and the open
low-grade valleys and abundant low cols of the region west of the
Appalachians, if the interpretation here given be correct. At the
opening of the Pliocene, therefore, the Appalachian tract is supposed
to have been affected by broad, flat, intermontane valleys, mantled
by a deep layer of residual decomposition products. The Piedmont
1 Rivers of Pennsylvania and Geographic Development of Northern New Jersey,
Nat. Geog. Mag., Vol. I and Vol. II, respectively.
2 Hayes, chapter on south Appalachians, in Physiography of the U. S. and 19th
Ann. Kept. U. S. Geol. Surv., Pt. II; Hayes and Campbell, Nat. Geog. Mag., Vol. VI.
306 GEOLOGY.
tract skirting the Appalachians is supposed to have been flanked on
the seaward side by a peneplain near sea-level, and on the other side by
broad, open valleys of low gradient. It is assumed that the upward
bowing was felt first in a relatively narrow belt along the predeter-
mined axis, that the rise was gradual, and that the rising arch increased
its breadth as it rose. The first bowing along the axis rejuvenated
the head waters of the streams which reached it, and the surface, deeply
mantled with residuum accumulated during the peneplaining stage,
readily furnished load to the streams in flood stages. When the
streams reached that portion of the peneplain not yet affected by
the bowing, they found themselves loaded beyond their competency,
and gave up part of their load. Thus arose a zone of deposition along
the bowed tract, as illustrated in Fig. 461. With continued rise, the
FIG. 461. — Illustrating the progressive stages of arching described in the text, and
the attendant shifting zones of deposition; s-s, sea-level; a, original peneplaned
surface with graded slope to sea-coast; a', a", afff, successive stages of arching;
b. bf, b", &'", successive zones of deposition corresponding to stages of arching a',
a", a'". In the stage of arching represented by a", the right hand portion of the
previous zone of deposition is lifted and becomes a part of the area of erosion. The
same process is carried farther in the next stage represented by a'".
mountainward border of the depositional zone is supposed to have
been shifted seaward, and the previous border elevated and subjected
to erosion, while the material removed was re-deposited in a new zone
farther from the axis of rise.
Thus the process is presumed to have continued till the border of
the lifted tract passed beyond the present sea-coast, after which the
whole mantle was subject to erosion, which had reached a notable
degree of advancement before the first known glacio-fluvial deposits
were laid down.
The hypothesis requires that the aggradation in each depositional
zone, when at its maximum, should develop a plexus of streams com-
petent to fill the shallow valleys and spread rather generally over
the low divides of the coastal peneplain, where relief was slight. In
the region of more pronounced valleys, such as the Tennessee, the
valleys were only partially filled. It has generally been assumed
that the formation was once continuous in the areas where patches
only now remain; but it may be that the higher divides, especially
THE PLIOCENE PERIOD. 307
toward the source of sediment supply, were never mantled by the
formation.
As set forth in Volume I, the overloading of streams is greatly
affected by the mode of precipitation and the vegetal covering of the
region. Diversifying agencies, particularly when attended by sub-
aridity, tend toward concentrated precipitation, which greatly acceler-
ates erosion. A change of vegetal covering, generally involving a
decrease in the amount of protection, usually accompanies a climatic
movement toward diversity and aridity, particularly if a reduction
of temperature attends the change. All these abetting agencies are
assignable with good reason to the Pliocene movement, not only on
general grounds, but on the specific implications of this formation,
as already indicated.
The erosion and re -deposition of material once deposited in the
manner sketched above, is regarded as an important feature, and the
source of grave difficulty in the correlation of the formation and its
derivatives. The erosion and re-deposition of the material during
the deposition of the main formation did not cease there, but has
been in progress to recent times, and the series of derivatives so closely
resemble the parent formation in structure and material that their
reference to their proper stages is exceptionally difficult. The close
resemblance of the derivative deposits to the parent formation in
structural features throws light on the mode of original deposition, for
in some cases the later method is certainly known.
If it shall ultimately be shown that the seaward portions of the
Lafayette, now concealed or unstudied, are marine, the preceding hypo-
thesis would need to be modified only by supposing that as the feeding
ground of the streams was bowed up, the coastal border of the plain
was submerged. In this case, there should have been estuarine for-
mations in the seaward valleys.
The chief alternative view relative to the origin of this strongly
characterized formation assigns it to marine deposition 1 during a
stage of submergence essentially co-extensive with the area of the for-
mation. This hypothesis has been faithfully applied by geologists
of wide familiarity with the phenomena and abandoned as untenable
even where the conditions seem most to favor it. It is, however, still
1 McGee, 12th Ann. Kept. U. S. Geol. Surv.
308 GEOLOGY.
entertained by others. The difficulties felt by those who have aban-
doned it are (1) the absence of marine fossils even where conditions
favor their preservation; (2) the presence of structural features not
identical with those of typical marine deposits; (3) the chemical
condition, particularly the high and very varying oxidation, and the
meager hydration, with a general absence of the reduction phenom-
ena connected with organic action beneath the sea; (4) the topo-
graphic relations of the formation, which are with difficulty reducible
to the requisite horizontality; and (5) the absence of characteristic
shore phenomena. Terraces have indeed been appealed to, but they
are local and doubtfully consistent with one another, and seem better
assignable to low gradient stream erosion through which this formation,
under any interpretation, must have passed, in rising from its primi-
tive low slope to its present higher one.
The Mississippi portion of this formation was formerly assigned
to glacio-fluvial action connected with the Pleistocene ice invasions,1
but this was due to its erroneous correlation with the Natchez formation,
which is essentially a derivative from the Lafayette, with a glacio-
fluvial contingent. It rests unconformably on the Lafayette, with
notable erosion between the two.
Marine Pliocene Beds.
The Atlantic coast. — If fossils be the test, Pliocene beds of marine
origin have but little development on the eastern side of the conti-
nent. In Florida only (Caloosahatchie beds) 2 have beds containing
marine fossils any considerable extent at the surface, though small
patches are known in Georgia, the Carolinas,3 Virginia, and perhaps
Massachusetts. The isolated outcrops in Virginia and farther south
may be parts of a continuous formation, chiefly concealed by younger
deposits. The beds in Massachusetts which have been regarded as
Pliocene occur at Gay Head,4 where they are unconformable on the
Miocene. Farther south also, the relations of the Pliocene beds to
their substratum is locally at least one of unconformity. The time
1 Hilgard, Agr. and Geol. of Mississippi, 1860.
2 Dall, Am. Jour. Sci., Vol. 34, 1887, p. 161, Wagner Free Inst. of Science, Vol. 14,
Pt. VI, p. 1604, Bull. 74, U. S. Geol. Surv.
3 Dall, Croatan beds of N. Carolina and Wassemer beds of South Carolina. Trans.
Wagner Free Inst. of Sci., Vol. Ill, Pt. II, pp. 201-17, 1892.
4 Dall, Am. Jour. Sci., Vol. 48, 1894, p. 299.
THE PLIOCENE PERIOD. 309
relations of these marine Pliocene beds to the Lafayette are undeter-
mined.
The marine fossiliferous Pliocene beds of the Atlantic coast con-
sist of shell marls, sand, and thin beds of limestone. In Florida, the
marine beds have a thickness of but a few feet. The gradual changes
in the character of the marine fossils from below upwards in the beds
show that a gradual shoaling of the water took place, until the species
proper to a moderate depth were replaced by those characteristic
of muddy shallows and tidal flats, and finally by an exclusively fresh-
water fauna.1
In addition to the marine Pliocene of Florida, there seem to have
been coastal lagoons and ponds in which fresh-water mollusks abounded.
Occasionally, however, the sea had access to the lagoons, either as
a result of slight changes of level of land or sea, or of severe storms,
so that marine fossils are sometimes associated with those of fresh-
water species. In addition to the coastal lakes and lagoons, there
were lakes in the low interior syncline of the peninsula.2
The Gulf coast. — Pliocene beds of marine origin have not been
certainly identified on the Gulf coast of the United States,3 west of
Florida, but they cover considerable areas farther south. Yucatan
is generally covered with marine Pliocene, and corresponding deposits
are known both to the north and south of that peninsula.4 In general,
the Pliocene beds of the tropical portion of the continent have not
been clearly separated from the younger Pleistocene beds, with which
their relations are said to be close. According to Hill, the great inter-
ruption in the Tertiary history of this region was in the later part of
the Miocene, or at its close.5 In the Antilles also, Pliocene beds are
known on the borders of some of the islands.6
The Pacific coast. — On the Pacific coast, the post-Miocene emer-
gence left little of the present land- area submerged; but a little later,
coastal depression allowed the sea to encroach upon the land to a
slight extent, and Pliocene beds were deposited unconformably on
1 W. H. DaU and G. D. Harris, Bull. U. S. Geol. Surv., No. 84, p. 191.
2 Ibid., Te goto beds, pp. 133, 324.
3 The upper part of the Grand Gulf series is referred to the Pliocene by Smith
and Aldrich, Science, New Series, Vol. XVI, p. 836.
4 Gabb, Lumon clays. Jour. Acad. Nat. Sci. Phil., Vol. VIII, 1881, p. 349.
5 The Geol. History of the Isthmus of Panama and Portions of Costa Rica.
6 Hill, Geology and Physical Geography of Jamaica, 1889.
310 GEOLOGY.
the Miocene, and on the older formations as well, at various points
along the western borders of the Pacific states. In no case do the
marine Pliocene beds extend far inland, though Pliocene beds con-
taining marine diatoms are said to have been indentified in southern
Arizona up to elevations of nearly 4000 feet.1 During the Pliocene
submergence, it has been thought that the islands of southern Cali-
fornia stood some 1500 feet lower than now.2 The thickest Pliocene
beds of the continent, so far as known, are in the peninsula of San
Francisco, where the Merced series (perhaps partly Quaternary,3 and
not all marine, as lignite shows) attains a thickness of more than 5800
feet,4 and in the Santa Clara valley where the thickness of Upper Plio-
cene (partly fluviatile) is said to be 8000 feet.5 Recently, a series of
beds below the Merced series, aggregating more than 7000 feet in
thickness and composed largely of volcanic debris, has been assigned
to the Pliocene.6 If this be correct, it gives the Pliocene of the Coast
range near San Francisco bay a thickness of some 13,000 feet. In
the San Luis Obispo region there are late Miocene or Pliocene for-
mations (Santa Margarita and Pisma, shale, sandstone, conglomerate,
etc.), of 4500 feet (maximum) thickness, overlain unconformably by
Pliocene beds (Paso Robles) of non-marine origin, 1000 feet in thick-
ness7 (Fig. 444). Other names (San Diego8 and Wildcat,9 Cal.,
and Mytilus,10 Ore.) have been applied to the marine Pliocene beds
of various localities on the Pacific coast.11 To some of these, as the
1 Blake, ScL, Vol. 15, p. 413, and Bumble, Jour. Inst. Min. Engineers, Vol. 31,
p. 696.
2 Smith, Bull. Department Geol. Univ. of Cal., Vol. II. Reviewed in Jour. Geol.,
Vol. VIII, p. 780.
3 The Messrs. Arnold, Jour, of Geol., Vol. X, pp. 117-138.
4 Lawson, Bull. Dept. Geol. Univ. of Cal., Vol. I, No. IV, p. 115 et seq. The upper
parts of the Merced of Lawson is put in the Pleistocene by Ashley, Proc. Cal. Acad.
Sci., 2d Ser., Vol. V, pp. 312-37, and the Messrs. Arnold, Jour, of Geol., Vol. X, p. 135.
5 Hershey, Am. Geol., Vol. 29, pp. 359-70.
6 Lawson, Science, Vol. XV, p. 410, 1902. The correlation of the beds between
the Monterey below and the Merced above, is not given in the publication. The
opinion that they are Pliocene is expressed by the author in a letter,
7 Fairbanks, San Luis, folio, U. S. Geol. Surv.
8 The Messrs. Arnold, Jour, of Geol., Vol. X, p. 129, and Ball, Proc. Cal. Acad.
Nat. Sci., Vol. VI, 1874.
9 Lawson, Bull. Dept. of Geol. Univ. of Cal., Vol. I, p. 255 and Ashley, Proc. Cal.
Acad. Nat. Sci., 2d series, Vol. V, 1895, pp. 312-331.
10 Condon, Am. Nat., Vol. XIV, 1880, p. 457, and Dall, Bull. U. S. Geol. Surv.
11 A good review of the Pliocene and Pleistocene of southern California is given
by the Messrs. Arnold, Jour. Geol., Vol. X, pp. 117-38.
THE PLIOCENE PERIOD. 311
Wildcat, great thicknesses (4600 feet) have been assigned. Marine Plio-
cene beds are not known to have great development farther north,
but beds tentatively referred to this period occur up to elevations of
5000 feet in the St. Elias Alps.1 It has 'been thought that Vancouver
and Queen Charlotte Islands were at this time connected with the
mainland.
The fossils of the Pliocene beds of the Pacific Coast are said to
indicate a climate cooler than the present.2 This may have been the
result of a broader connection than now between the Arctic and the
Pacific.
Crustal Movements of the Pliocene.3
The tendency to crustal movement both by warping and by faulting,
which characterized the western part of the continent during the
earlier part of the Tertiary, seems to have continued at least inter-
mittently through the Pliocene, though the movements which took
place during the period are not always distinguishable from those of
earlier times, or from those which took place at its close. Deforming
movements often extend through long periods, and the Pliocene move-
ments were in many places probably no more than continuations of
movements begun in an earlier period, and continued into a later.
About the close of the Pliocene there seem to have been wide-
spread crustal movements in most parts of North America. They
resulted in increased height of land, and the time of active erosion
which followed is sometimes known as the Ozarkian 4 or Sierran 5
period. In the east, the region overspread by the Lafayette formation
was somewhat higher than now, and in reaching this position, it was
perhaps somewhat deformed, though by no means all of the pecu-
liarities of topographic distribution (p. 302) are to be ascribed to defor-
mation, if the preceding explanation of the formation be correct. With
the elevation of the coastal plain, the coast line was probably shifted
1 Russell, National Geol. Mag., Vol. Ill, pp. 171-2.
2Dall, op. cit., and the Messrs. Arnold, Jour, of Geol., Vol. X, p. 125.
3LeConte, Jour. Sci., Vol. XXXII, p. 167, 1886, Bull. Geol. Soc. Am., Vol, II.
p. 329, Jour, of Geol., Vol. VII, p. 546, 1899; Hershey, Science, Vol. Ill, p. 620, 1896;
McGee, 12th Ann. Rept. U. S. Geol. Surv. and Science, Vol. Ill, p. 796; also King,
op. cit., and Button, Mono. I, U. S. Geol. Surv.
4 Hershey, Science, Vol. III. p. 620, 1896.
8 LeConte, Jour, of Geol., Vol. VII, p. 529.
312 GEOLOGY
eastward, perhaps to the edge of the continental shelf, across which
streams may have flowed, cutting valleys in its surface. To this
epoch, the notable submerged continuations of the St. Lawrence, the
Hudson, the Delaware, the Susquehanna, and the Mississippi are com-
monly referred. Some of these valleys have great depth, and it has
been assumed that their depth was a measure of the elevation of the
land at the time they were excavated. But if the considerations set
forth in Chap. XX have force, it is not necessary to postulate such extraor-
dinary changes of level by uplift and depression. Continental creep
along the steep slope between the continental platforms and the oceanic
basins may have depressed the valleys notably while it extended
them seaward. The earlier assumption that the land along the Atlantic
seaboard must have stood 2000 to 3000 feet, or perhaps even 7000
to 12000 feet,1 above its present level, to allow of the excavation of
these valleys, seems therefore unnecessary.
During the post-Lafayette interval of elevation and erosion along
the Atlantic coast, much of the material of the mountain-ward edge
of the Lafayette formation was shifted seaward, and redeposited along
the lower courses of the streams.
In the Mississippi basin there was also notable elevation at this
time. It seems possible, or perhaps even probable, that the evolu-
tion of the principal physiographic features of the interior, so far as
due to erosion, began with the Ozarkian epoch, though the study
of the evolution of the topography of this region has not advanced
so far as to make this conclusion certain. The amount of uplift in
this region at this time was probably less than has sometimes been
estimated.
In the west, too, there were notable post-Tertiary movements.
The plateau region was in process of uplift, periodically, throughout
the Tertiary, during which it has been estimated to have undergone
an elevation of 20,000 feet (Dutton), and a degradation of 12,000, leav-
ing it 8000 feet above sea-level. How much of this is assignable to the
Sierran epoch is uncertain. It was Dutton's view that the Colorado
plateau was so elevated at this time as to rejuvenate the Colorado
River, and that the cutting of its inner gorge some 3000 feet (maxi-
mum) below the outer (p. 275), was the work of later times. More
1 LeConte, op. cit., and Spencer, Am. Jour. Sci., Vol. XIX, pp. 1-15, 1905.
THE PLIOCENE PERIOD 313
recent studies indicate that even the outer and broader part of the
valley, the esplanade, is younger 1 than was formerly thought, per-
haps post-Sierran, and raise a question as to whether the inner gorge
is not the topographic result of rock structure, rather than of a dis-
tinct and later uplift.2 If the whole of the canyon is post-Sierran, the
elevation of the region in the Sierran epoch (and later) must have
been several thousand feet. The later elevations, largely by blocks,
were so recent that the fault scarps are almost always ungraded and
precipitous, and independent of stratigraphy and drainage.3
In the basin region, faulting and deformation were in progress,4
and gave rise to two basins, one at the west base of the Wasatch
mountains, and the other at the east base of the Sierras. These depres-
sions prepared the way for two great Pleistocene lakes (Bonneville
and Lahontan). It is probable that many other faults between the
Rockies and Sierras were developed at the same time, and in many
cases at least the movement seems to have been along fault planes
established before the Pliocene period. Some idea of the great erosion
which has affected the Uinta mountain region, since the Eocene at
least, is gained from Figs. 462 and 463
FIG. 462. — Section across the Uinta mountains Pru, Uinta group Proterozoic (?);
Cntf, Lodore and Red Wall formations, the former probably Cambrian, the lat-
ter Mississippian; Cla, Lower Aubrey, and Cua, Upper Aubrey, are Carboniferous
(Mississippian and Pennsylvanian) ; T and J, Triassic and Jurassic formations
(Flaming Forge, White Cliff, Vermilion Cliff and Shinarump formations); Ksl
(Sulphur Creek and Henry's Fork formations), Ksv) (Salt-wells formation), and
Kpr (Point of Rocks formation), Cretaceous; Ebc (Bitter Creek group) and Ebp
(Brown's Park group), Eocene. (After Powell.)
In the Sierra region, the post-Tertiary (or late Tertiary?) uplift
was still more marked.5 The earliest Sierran folding of which the
history is well known, was at the end of the Jurassic period.
1 Huntington and Goldthwaite, Bull. Mus. Comp. Zool. Geol. Ser. , Vol. VI, p. 252.
While these authors do not state the time of the beginning of the canyon, they say
that " the canyon cycle (of erosion) must include at least the later part of the glacial
epoch."
2 Davis, The Grand Canyon of the Colorado, Bull. Mus. Comp. Zool., Vol. XXXVIII.
3 Huntington and Goldthwaite, p. 248.
4 King, U. S. Geol. Expl of the 40th Parallel, Vol. I, p. 542.
'LeConte, op. cit., and Diller, 14th Ann. Rept. U. S. Geol. Surv.
314 GEOLOGY.
" What kind of a mountain it was at that time, how high, and what its con-
figuration, we know not; for the continuous erosion of the Cretaceous and Ter-
tiary times had nearly swept it clean away. The cycle of its mountain life had
reached its last stages. By continuous erosion it had been reduced to a pene-
plain, with its wide-sweeping curves of broad shallow channels and low-rounded
divides. The rivers had reached their base-levels and rested. This was the
work of the Cretaceous and Tertiary.
" Then came the post-Tertiary rejuvenation of the mountain life, by the
formation of a fissure on the eastern slope, the heaving of the whole mountain
block on its eastern side with a great eastern fault scarp; the transference of
FIG. 463. — Represents the outline of the Point of Rocks formation of the last section,
as it would have appeared without erosion, after faulting. The length of the sec-
tion is about 57 miles. The vertical scale is the same as the horizontal. The
displacement at P is nearly 20,000 feet. (After Powell.)
the crest to the extreme margin with great increase of the western slope and
consequent revival of the erosive energy of the rivers. Coincident with this
in middle California there was a great outpouring of lava, which ran in streams
down the western slope, filling up the old river-beds, and displacing the rivers.
The displaced rivers, with recently and fiercely aroused energy, immediately
commenced cutting new channels, which are now 3000 to 6000 feet deep, and
far below the old; so that these latter are left with their lava-covered gravels
high up on the present divides. This was the work of the Ozarkian." l
Not only the deep canyons, but all the scenery of the high Sierras
is post-Tertiary. " Its bold, rugged, savage grandeur is due to its
extreme recency. The wildness of youth has not been tempered and
mellowed by age."2 It should be added that the beginning of the
re-elevation of the Sierras, after peneplanation, is usually placed in
late Miocene time.
Near the Pacific coast, too, notable changes marked the closing
stages of the Pliocene and the transition from it to the Pleistocene.
In some parts of southern California (Fort Frazer, Los Angeles County)
marine Pliocene beds are said to occur up to altitudes of 6000 feet,3
and in others (San Luis Obispo), there was folding (Fig. 444) and fault-
ing at the close of the Pliocene, while the shore-line was pushed out
'LeConte, Jour. Geol., Vol. VII, p. 529-530.
2Le Conte, loc. cit., p. 530.
3 Hershey, Am. Geol., Vol. 29, p. 364.
THE PLIOCENE PERIOD. 315
to near the edge of the continental shelf.1 There was notable fault-
ing in the Santa Cruz mountains of California at the end of the Plio-
cene, with uplift of the axis, while the flanks of the range remained
submerged.2 The wide-spread unconformity between the Pliocene
and Pleistocene of the Pacific coast, is a further index of the great
changes of the time.
There are submerged valleys3 along the Pacific coast, as along
the Atlantic, but their excavation, instead of following the Ozarkian
uplift, is thought to have been the result of the post-Miocene move-
ment which folded up the Coast range, and shifted the coast line west
to the edge of the continental shelf. Some of them differ from the sub-
merged valleys of the Atlantic coast, in not being the continuations of
existing land valleys. The late Pliocene movements and lava flows,
the latter filling many of the valleys, so disturbed the drainage that
the streams no longer reached the sea at the same points as before.
In Washington, present knowledge seems to point to the early
Pliocene as a time of prolonged erosion. The crests of the Cascade
mountains seem to represent remnants of a deformed peneplain which,
carried to the east and south, is continuous with an erosion plain,
which cuts across strata (Ellensburg formation) of late Miocene 4 age.
The planation must, therefore, have been later than that part of the
Miocene period represented by the beds concerned. At least the
early part of the Pliocene period, if not most of it, would seem to have
been necessary for the accomplishment of this great planation, so
that the peneplain can hardly be thought to antedate late Pliocene
(Ozarkian) time. If this view be correct, the main features of the
present topography of that most rugged region are the result primarily
of late Pliocene and Pleistocene erosion on the peneplain which was
uplifted and deformed in late Pliocene time, and secondarily of vul-
canism, which has built up the great volcanic piles (Rainier and others)
which affect the region.
In British Columbia also, the Pliocene is thought to have been
primarily a time of erosion. According to the interpretation of those
1 Fairbanks, San Luis folio, U. S. Geol. Surv.
2 Ashley, Journal Geol., Vol. III.
3 LeConte, Bull. Geol. Soc. of Am., Vol. II, p. 325
4 Smith, Ellensburg, Wash, folio, U. S. Geol. Surv.; also Willis and Smith, Pro-
fessional Paper 19, U. S. Geol. Surv.
316 GEOLOGY.
who have studied this region, broad valleys, which have subsequently
been elevated 2000 feet or more, were developed during the Pliocene.
Near the close of the period there was further elevation in this region,
and deep valleys were cut in the bottoms of the broad ones already
in existence. These valleys were continued out across the continental
shelf. Subsequent subsidence (and creep) has transformed part of
the valleys developed at this time into fiords.1 The valley lakes of
this region occupy depressions which are thought to have been largely
excavated at this time, and subsequently transformed into basins by
warping, by glacial gouging, and by obstruction with glacial drift.
It will be seen that the interpretations which have been put on
the phenomena in Washington and British Columbia are not altogether
consistent. They would be brought into harmony if the broad valleys
of the latter region, referred to the Pliocene, amounted to virtual pene-
planation of the region concerned. The amount of post-Pliocene
erosion in the Cascades, according to Smith and Willis, is much greater
than that in the Grand Canyon region, according to Button's inter-
pretation, but is more consistent with the later interpretations.
Deformative movements of the orogenic type seem not to have
been common at the close of the Pliocene, but such movements affected
the Santa Cruz mountains of California, where Miocene (Monterey)
and Pliocene (Merced) beds were deformed together.2 After the
deformation the range is thought to have been 1000 to 1200 feet higher
than now.
On the whole, the close of the Pliocene must be looked upon as
a time of great crustal movement, a critical period in the history of
North America. New lands were made by emergence from the sea,
and old lands were deformed and made higher; new mountains were
made, and old ones rejuvenated; streams were turned from their
courses in some places, and nearly everywhere started on careers of
increased activity. The Ozarkian epoch, the transition from the Ter-
tiary to the Pleistocene, was, so far as North America is concerned,
an epoch of great erosion. The fact that such notable changes, with
increased elevation of land, occurred during the epoch next preceding
the glacial period, led to a wide-spread belief that the elevation was
the cause of the climate of the latter period; and while there may
1 Dawson, Science, Vol. XIII, 1901, p. 401
2 Ashley, Jour. Geol., Vol. Ill, p. 434.
THE PLIOCENE PERIOD.
317
be a connection between them, it was probably not in the simple and
commonly accepted sense.
The volcanic activity of preceding periods continued into the Plio-
FIG. 464. — Map and section of the Marysville, Cal., volcano; Et, Eocene (Tejon for-
mation) ; Ni, Miocene (lone formation) ; Ql, Quaternary (river gravels) ; Na,
andesite, Nr, rhyolite, and Nat, andesite tuff. Area of the map about 100 square
miles. (Lindgren and Turner, Marysville, Cal. folio, U. S. Geol. Surv.)
cene, and became somewhat pronounced near the end of the period,
in different parts of the Cordilleran system. Some of the late igneous
formations of the Sierras, and perhaps of northern California/ belonged
to this time, and probably some of those of nearly or quite every other
state west of the Rocky mountains. Many of the prominent volcanic
1 Hershey, Jour, of Geol., Vol. X, pp. 377-392.
318 GEOLOGY.
peaks of the west date from this time, or later. The building of these
cones appears to represent the later phase of the prolonged period of
volcanic activity, just as the great lava flows and intrusions represent
the earlier. Lesser cones in many places are probably to be referred
to the same period.
Foreign.
From considerable areas of Europe covered by water during the
Miocene, the waters retreated late in the period, or at its close. The
sea still covered some parts of the continent, and at some points it
extended itself at the expense of the land. Southern and southeastern
England, Belgium, and perhaps a little of northern and parts of western
France, were under water during at least some part of the Pliocene,
but the submergence was not everywhere continuous from the Mio-
cene, for the Pliocene sometimes (some parts of Belgium) rests with
well-developed unconformity on Miocene and older beds. The sea
covered much more extensive areas of the present continent about
the Mediterranean, where parts of southern France (Rhone basin
as far north as Lyons), Spain, Italy, Sicily, and Greece, were still
submerged. Beyond the inland margins of the marine Pliocene, there
are beds of lake or river origin. In southeastern Europe, brackish and
salt lakes came into existence, as shown both by the fossils and the
local deposits of salt and gypsum. In other places, sedimentary deposits
were made in fresh lakes and river valleys, and in both, remnants of
terrestrial life are found. Locally (Turkey), naphtha is said to be derived
from the Pliocene.1
The beds deposited at this time show a culmination of the ten-
dency to local variation characteristic of the Tertiary. This was the
necessary result of the separation and isolation of the areas of depo-
sition.
In England the lower part of the Pliocene is marine, and the upper
part lacustrine, fluvial, and pluvial, as if the sedimentation shut out
the sea. The system here attains a maximum thickness of between
100 and 200 feet. Here belong the beds known as Coralline Crag,
Wealden Crag, Norwich Crag, Chillesford Crag, and Weyburn Crag,
names applied to layers often no more than 10 feet in thickness.
'English, Q. J. G. S., 1902, p. 80, and 1904, p. 265.
THE PLIOCENE PERIOD.
319
In Belgium the thickness of the system is much greater, and con-
sists chiefly of sand. In France the system contains volcanic mate-
rial mingled with the sedimentary. The marine beds of southeastern
France (Rhone basin) are unconformable on older rocks, and reach
an elevation of 1150 feet. They extend up the valley of the Rhone,
and their limit in this direction marks the northern limit of the depo-
FIG. 465. — Sketch-map of Europe during the Pliocene period. The broken lines
indicate areas of lacustrine and non-marine deposition. The full lines, the area of
marine deposition. (After De Lapparent.)
sition in the southern Pliocene sea. The materials are largely uncon-
solidated.
Among the alluvial and lacustrine beds of the period, those of
the basin of Mayence should be mentioned. They contain, along
with the ordinary varieties of sediment, lignite, with plants of North
American types. In the Vienna basin also are Pliocene deposits,
brackish water beds below and fluvial beds above. In Italy only, do
the Pliocene beds attain massive development. Along the Apennines,
the system has been variously estimated at from 1600 to 3000 feet
320 GEOLOGY.
in thickness, and in Sicily 2000 feet. Limestone as well as clastic
beds enter into the system, and they occur up to heights of 3000 feet.
Sedimentation was brought to an end by the mpvements which culmi-
nated in the outbreak of Vesuvius, Etna, and other Italian volcanoes.
Etna at least, was first submarine, for its older tuffs are interstratified
with marine beds. Later, by elevation, or by the upward growth of the
volcanic cones, or both, the eruptions became subaerial.
Marine Pliocene is known in Egypt, where the sea is thought to
have extended up the Nile to Assuan. The formation of the rifts of the
Red Sea and the Gulf of Suez, has been assigned to the Pliocene period,1
though the rift origin of these depressions has not been universally
accepted.2 Pliocene beds have also been reported from Tibet3 (non-
marine), India,4 Borneo,5 and the Philippines.6
The Life of the Pliocene.
The land plants. — The Pliocene was characterized by a still fur-
ther sorting out of the mixed flora of previous periods, and by the
southerly migration of what are now tropical and sub- tropical plants.
Whether there was a northerly shifting of the opposite class of plants
has not been determined. In southern France there were still some
species identical with those now living in the Canaries. In Europe
generally also, there was still much commingling of species that have
since become geographically separated. Some of this was separation
in longitude, and does not carry climatic suggestiveness. There were
some genera that have since been driven eastward to the Caucasus,
and some that are now characteristic types in North America, and so
the flora had a somewhat American aspect. The tenor of available
evidence, however, indicates not only a general differentiation, but a
movement in latitude antecedent to the present distribution and
adaptations of the plants. This has usually been interpreted as sig-
nifying a progressive refrigeration of the earth's climate, consonant
with the conception of a progressive cooling of the globe, and an approach
to a permanent condition of refrigeration; but other lines of evidence
i Barren and Hume, Geol. Mag., 1901, p. 156.
2Mennell, Geol. Mag., 1903, p. 548.
'Lydekker, Q. J. G. S.f Vol. LVII, p. 292.
4 Oldham, Geology of India.
6 Molengraaf, Geol. Expl. in Central Borneo, Rev. Geol. Mag., 1903, p. 170.
6 Becker, 21st Ann. Kept. U. S. Geol. Surv., Pt. III.
THE PLIOCENE PERIOD. 321
do not altogether tally with this conception, and suggest rather that
this was but one of the oscillations of climate that must now be recog-
nized as marking geologic history. That the climate was becoming
differentiated, and on the whole cooler than it had been in the earlier
Tertiary periods, is clearly indicated.
The land animals. — The history of the mammals continued to be
the one great center of interest. Three important features characterized
it: (1) A notable intermigration of the continental faunas, including
those of North and South America, (2) the initiation later of the present
divergence between Old and New World types, and (3) the culmina-
tion and perhaps initial decline of the evolution of the placentals, the
human and domestic species aside.
The accelerated intermigration of the early part of the period was
a natural consequence of the extension of the land connections brought
about by deformative movements. The precise nature of these land
connections has not yet been worked out in all the details necessary
to a satisfactory interpretation of the biological events of the period.
There are outstanding problems as to the extent and continuity of
the the connections between Eurasia and America at the northwest
and at the northeast, but the evidence of good migratory routes for
the land animals, during a portion of the period at least, may be accepted
as conclusive. There are also strong hints of the progressive develop-
ment of a selective bridge-and-barrier which afforded free passage
for some species and shut off others, and this is assignable to increasing
cold in the later stages of the period, leading up to the glacial period
which followed. This was probably the chief influence in developing
the divergence between the mammals of the Old and the New Worlds,
for this divergence affects mainly the warm-latitude species.
The connection between North and South America introduced a
biological movement of dramatic interest. There appears to have
been no effective isthmian thoroughfare for land animals between
the earliest Eocene and the Pliocene or thereabouts, when a way was
opened. During the time of the Eocene connection a few mammalian
types seem to have sent representatives into South America, and these
had evolved on distinctive lines in the interval. A very remarkable
group of sloths, armadillos, and ant-eaters had developed from an
edentate stem: strange hoofed animals of orders unknown elsewhere
(Typotheria, Toxodontia, Litopterna) had arisen from some very primi-
322 GEOLOGY.
tive ungulate form; monkeys of the South American type had evolved
probably from a North American Eocene lemuroid, while rodents of
the porcupine type, but not of other orders, had been derived from
some unknown immigrant form. That the connection was only par-
tial or very temporary, seems to be implied by the absence of most
of the great North American groups, such as the creodonts, carnivores,
condylarths, artiodactyls, perissodactyls, and insectivores. The absence
of proboscidians implies a lack of connection between South America
and Africa, where these forms had been developing during the Eocene
and Miocene. Many carnivorous and herbivorous marsupials closely
similar to those of Australia lived during this interval in South America,
implying either connection in that direction, or pronounced parallel
evolution. If the former, it is unknown whether the migration was
toward or from South America. This remarkable South American
fauna is a striking instance of evolution on a large scale in comparative
isolation, and in relative freedom from the severe stimulus of effective
competition, powerful carnivores, and shifting geographic relations.1
On the opening of connection between the two Americas in Plio-
cene times, the faunas of each division invaded the other. Horses,
mastodons, deer, carnivores of the dog and cat families, llamas, and
tapirs from the north invaded South America, while certain gigantic
sloths (Megatherium, Mylodon, Megalonyx, and Glyptodon) invaded
North America. The latter group did not maintain themselves in
North America beyond the Pleistocene period, whether because of
the physical environment, the ice invasions, or the struggle with a
superior fauna, cannot be affirmed. The northern invaders were more
successful in South America though not conspicuously so, as only a
portion of them have living descendants there.
That the extraordinary evolution of the undomesticated placentals
experienced a decline at the close of this period was a natural result
of the glacial invasions that followed, and of the even more potent
influence of man.
During the period, the evolution of the mammals pursued essentially
the same lines as before. The herbivores continued to occupy the fore-
most, as well as the fundamental place. Both the odd- and even-toed
ungulates completed their deployment into all their present families,
1 For late data see the Reports of the Princeton University expedition to Pata-
gonia, 1896-99.
THE PLIOCENE PERIOD. 323
and very generally into their present genera, and were also represented
by many genera and numerous species which are now extinct. A list
of Pliocene families would be little more than a catalogue of those
now living. The evolution of the horse was advanced to the existing
genus, Equus. The hornless rhinoceros continued in North America
till near the close of the period, and then passed away. The horned
branch flourished in the Old World, while the tapir disappeared from
Europe. Giraffes and giraffe-like animals (Samotherium, Helladotherium,
Sivatherium, Bramaiherium, Vishnutherium), some of them of gigantic
dimensions, invaded southern Europe and Asia, coming probably from
Africa. The three last named have been found in the great Siwalik
formation of India.
The giants of the period were the proboscidians. The Dinothe-
rium may be regarded as an aberrant side branch that suffered the
usual fate of such branches — early extinction. It was somewhat widely
distributed in Europe and has been found in India, but is not known
to have reached America. The mastodons seem to have occupied
all the continents during the Pliocene, but it is doubtful whether the
elephant reached the American continent before the Pleistocene.
Some of the early mastodons had tusks in the lower as well as upper
jaw (Tetrabelodon), but the most of the Pliocene species had tusks in
the upper jaw only, in the adult state (Dibelodori) . The mastodons
were very closely related to the elephants, and are most conveniently dis-
tinguished by the teeth, the molars of the former being crowned by
conical tubercles, while those of the latter are marked by transverse
folds of enamel, separated by cement (Figs. 466 and 467). The ele-
phants appear to have flourished abundantly in Europe, and with the
associated rhinoceroses and hippopotamuses gave to the European
fauna an African aspect.
The carnivores of both continents flourished and perhaps gained
somewhat upon the herbivores; at any rate they put a severe tax on
the herbivores, forcing still further adaptations in the line of alert-
ness, sagacity, speed, and defense, and gaining similar qualities them-
selves. Besides most of the existing genera, the ferocious " saber-
toothed tiger " (Machcerodus) and some other extinct forms still existed.
The rodents appear to have held about their present place relatively.
Supreme interest attaches to the development of the primates in
this period, but as yet the data are limited and are likely to remain
324
GEOLOGY.
so until the tropical regions of the Old World are more fully studied,
for the chief evolution seems to have taken place there. No remains
of lemuroids or of their descendants have been found in the Pliocene
beds of North America. In Europe, all such remains thus far recovered
FIG. 466. — Teeth of mastodon (Mastodon longirostris) , showing slightly worn tubercles
at the right and much worn ones at the left. (From Gaudry, after Kaup.)
have been limited to the middle and southern portions, a limitation
which is hardly accidental, and which probably implies that the cli-
mate of northern Europe was already becoming uncongenial to the
primates. There are indeed signs of a gradual abandonment. The
FIG. 467. — Teeth of elephant (Elephus primigenius) , with the transverse ridges differ-
entially worn, showing dentine in the center, the enamel, which forms the crenu-
lated loops, supported by dentine within and cement without. (After Owen
and Metcalfe.)
Paidopiihex, a representative of the higher apes, seems to have left
Europe in the earlier Pliocene. The lower apes (Cercopithecidce)
remained longer, and the Macacus (the Barbary ape) still lives on the
rock of Gibraltar. The Macacus appears to have had considerable
THE PLIOCENE PERIOD.
325
range in Europe in the late Pliocene and early Pleistocene periods,
and it is still the most widely distributed member of its family. The
best known of the Pliocene tailed apes, the Mesopithecus, left abundant
relics at Pikermi, near Athens. The Mesopithecus was closely related
to the present Indian Semnopithecus, on the one hand, and to the Macacus,
on the other. An allied genus, Dolichopithecus, which lived in France,
is interesting on account of its large and long skull. The tropical
FIG. 467a. — Head of Smilodon, — a saber-toothed tiger. Outline restoration, showing
the widely-gaping jaws. (After Knight.)
deposits will doubtless tell an interesting story of primate evolution
when carefully studied.
Much the most interesting discovery of recent date is that of the
remains of a man-like skeleton found near Trinil in Java and named
Pithecanthropus erectus. The relics include the roof of a skull, two
molar teeth, and an abnormal femur. The form of the last indicates
that its possessor walked erect, in a sense that distinguished it from
the apes. The forehead was low and the frontal ridge prominent,
and in general the characteristic features were intermediate between
those of the lowest men and of the highest apes, as shown in Fig. 468.
The brain volume was about two thirds that of an average man. The
interpretation of these remains has elicited much difference of opinion.
By some they are thought to represent a dwarfed and diseased man;
326
GEOLOGY.
by others, to belong to an ancestral type between man and his more
remote ancestry, which is not supposed to be simian, but an independent
phylum.
The marine life. — The record of American marine life on the Atlantic
coast is extremely meager. During the larger part of the period the
coast-line was probably farther out than it is now, and the record is
inaccessible. The few forms found are very similar to those now
Lni
FIG. 468. — Profile of the skull of the Pithecanthropus erectus (line Pe), compared with
profiles of the lowest men and highest apes: Spy I and Spy II, the men of Spy: Nt,
the Neanderthal man; HI, a gibbon (Hylobates leuciscus): Sm, an Indian ape
(Semnopithecus maurus)', and At, a chimpanzee (Anthropopithecus troglodytes).
(After Marsh.)
living. On the Pacific coast there is a better representation,1 but
even this probably represents only a small portion of the period, and
it is not certain which portion this is. The fauna is very similar to
that now living in the waters off shore. As recorded at San Pedro,
it has many species (18.5%, Arnold) now found living only at points
farther north, and most of the other species are now more abundant
to the north. This has led to the inference that the climate was then
somewhat colder than now. As in previous periods, the gastropods and
pelecypods greatly predominated.
1 Mem. Cal. Acad. Sci., Vol. Ill, 1903, Ralph Arnold.
CHAPTER XIX.
THE PLEISTOCENE OR GLACIAL PERIOD.
THOUGH it derives its systematic name from the fact that its life
constitutes the closing stage of the transition from the great past to
the present, the distinguishing feature of the Pleistocene period is
its phenomenal glaciation. Ice-sheets spread over six or eight million
square miles of the earth's surface where not long before mild climates
had prevailed. Were it not for this great ice deployment, and for
its profound effects on the conditions under which man has developed,
this period would more properly be joined to the Pliocene, the two con-
stituting a single period of great land relief and oceanic restriction.
The time assigned the Pleistocene is much shorter than that of the
average geologic period. It appears that the later periods, as a rule,
are shorter than the earlier ones, due to our magnifying the import-
ance of events that are near to us. The Pleistocene expresses this
more markedly, perhaps, than any other period. The importance
of the Pleistocene period has, however, been greatly increased by
recent investigations, not only in respect to its length, but also in
respect to its diversity and its bearing on human evolution.
General Distribution of the Glaciation.
More than half of the area of the Pleistocene glaciation lay in North
America, and more than half of the remainder lay in Europe. The
glaciation was, therefore, pronouncedly localized, as was that of the
Permian period, and probably also that of the still earlier Cambrian
or pre-Cambrian. But the whole world felt its effects; even in the
tropical regions, glaciation occurred on mountains where it did riot
exist before and does not now exist, and on mountains now glaciated
the ice descended to levels 5000 feet or more below its present limit.
The southern hemisphere was affected as well as the northern,
327
328 GEOLOGY.
but to a much less degree. In Patagonia and New Zealand, glaciers
crept down from the mountains and spread out on the lowlands to
notable extents. Glaciers formed on the mountainous tracts of Tas-
mania and Australia where none exist now. The higher mountains
of the southern hemisphere generally bore glaciers even in low lati-
tudes. Antarctica was presumably buried beneath ice as now, but
this is purely a matter of inference. Notable as was this glaciation
of the southern hemisphere, it was insignificant compared with the
deployment of ice in the northern hemisphere.
In Asia, ice fields much greater than those of the present time
affected the higher mountains. Though its extent is but partially
known, former glacial work has been recognized at various points from
the Lebanon and Caucasus mountains in the southwest, eastward
along the high ranges to the Himalayas and the high mountains of
China, arid northward to the ranges of eastern Siberia. On the plateaus
and lowlands of Asia, ice-sheets were far less extensive than in Europe
and North America. It has been both affirmed and denied that the
Mongolian plateau was glaciated. The northern border of Siberia
in the region of the Taimur peninsula, and again in the far northeast,
was covered with ice, and glaciers descended from the northern Urals
to the plains of the Obi. With the exception of a portion of the Siberian
tract, all the Asian glaciation was associated with high altitudes.
In Europe, there were large glaciers in the southern mountains and
extensive ice-sheets on the northwestern plains. Radiating from the
Scandinavian highlands, a succession of great ice-sheets crept forth
upon the lowlands of Russia, Germany, Denmark, Holland, and Bel-
gium, and, apparently crossing the shallow basin of the North Sea,
touched the shores of England and Scotland, where they were met by
ice radiating from the mountains of Great Britain (Fig. 528). From
the Alps, gigantic glaciers descended to the lowlands in all directions.
Thus the Rhone glacier moved out far beyond the mountains, and
became confluent with glaciers from the mountains of Savoy and
Dauphiny, on the plains of France;1 while from the southern Alps,
glaciers descended to the plains of Italy. Glaciers of similar dimen-
sions descended into the valleys of the Rhine and the Danube. The
Pyrenees, some of the higher mountains of the Spanish plateau, the
1 Geikie, J., Outlines of Geology, p. 373.
THE PLEISTOCENE OR GLACIAL PERIOD.
329
higher mountains of France, the Apennines, the Carpathians, the
Balkans, the Caucasus and the Urals, all had their glaciers, while from
the northern Ural and Timan mountains ice-sheets descended into
the basin of the Pechora. Iceland and the Faroe Islands were buried
FIG. 469. — Sketch-map showing the North American area covered by ice at the maxi-
mum stage of glaciation.
in ice, and even Corsica had snow-fields and glaciers, some of which
were not diminutive.
Nearly one half of North America was buried in ice (Fig. 469).
Strangely enough, it was not strictly the northern half, but the north-
eastern half, that was specially ice-invaded, and, more strangely still,
330 GEOLOGY.
not so much the mountainous portions, though these were affected,
as the plains. Alaska was largely free from ice except on or about
the mountains, and continuous glaciation did not extend as far south
on the mountain-girt plateaus of the Pacific border as on the smooth,
low plains of the Mississippi valley. Much the greater part of the
4,000,000 square miles of the ice-fields lay on the plains of Canada
and in the upper Mississippi valley. The Missouri and Ohio rivers,
like two great arms, embraced the borders of the greatest of the ice-
sheets to which they owe their origin. The special features of this
predominant glaciation first invite our attention.
The Glaciation of North America.
The centers of glacial radiation. — In North America, three great
centers of glacial radiation, besides Greenland, have been recog-
nized. These are the Labradorean, the Keewatin, and the Cordilleran.
From these centers, ice-sheets spread forth covering some 4,000,000
square miles (Fig. 469). The centers from which the last radiations
of ice took place are determined with certainty by glacial striation
and by the lines of transportation of drift. The centers of the earlier
radiations of ice, where overridden by the last, are less positively
known, but no serious misconception is likely to be gained, if the cen-
ters of dispersion in the late glacial epochs are regarded as the cen-
ters in all. These centers are indicated in Fig. 470, where the lines
of movement, the extension in different directions, and the configura-
tion of the borders at certain stages are indicated. From this map
it will be seen that the radiation was unsymmetrical in all cases, being
greatest southward, southwest ward, and westward.
From the Labradorean center, the extension was notably greatest
to the southwest, in which direction the limit is only found some 1600
miles from the center of dispersion. This limit lies in about 37° 30'
latitude, and is the most southerly point of the great lowland glaciation
of the period. The extension of the Keewatin ice-sheet to the south-
ward was scarcely less great, finding its limit in Kansas and Missouri,
about 1500 miles from its center, while to the west and southwest
it extended 800 to 1000 miles toward the foot-hills of the Rocky Moun-
tains.
The details of ice movement northward from these two centers are
not well known, but the fact of general northward movement is estab-
FIG. 470.— Map showing the glaciated area of North America. The heavy line across
the United States represents the limit of glaciation. The lobate outline of the
ice of some of the later stages is also shown. The arrows back from the edges
of the drift-sheets indicate direction of ice movement, as recorded by striae. The
clotted lines represent direction of movement generalized from the recorded striae.
They radiate from the three centers indicated in the text. The short arrows
in the western part of the United States indicate the general distribution and
direction of movement of the ice in that part of the continent. There were doubt-
less glaciers in some areas where they are not represented.
331
332 GEOLOGY
lished. The Keewatin sheet pushed northwestward to the mouth of
the Mackenzie, and probably to Banks Land; northward and northeast-
ward to the Arctic Islands,1 and eastward to Hudson Bay, and into
confluence with the Labradorean sheet. The latter pushed northward
into Ungava Bay, eastward into the North Atlantic, and southeast-
ward into the Gulf of St. Lawrence.
One of the most marvelous features of the ice dispersion was the
pushing out of the Keewatin sheet from a low flat center, without
even a suggestion of a mountainous nucleus, 800 to 1000 miles west-
ward and southwestward over what is now a rising and semi-arid
plain, while the mountain glaciation on the west, where now known,
pushed eastward but little beyond the foothills.
There were probably some important variations from the present
altitudes which influenced the spread of the ice. The western region
was probably relatively lower, arid the eastern relatively higher than
now; and while there is no question but that topography is an influ-
ential factor in controlling the movement of glacial ice, it is probable
that differences of precipitation on the different sides of the ice-sheets,
and the consequent differences of topography of the ice-surface were
still more important. Differences in the mobility of the ice, due to
differences of temperature were also probably effective. In general,
it is probable that the factors of growth and mobility take precedence
over the topography of the bed in determining the course of movement
where thick and extensive bodies of ice are involved, for they not only
determine the distribution of the material that is to move, but they
:develop an ice topography, and sometimes a quasi-fluency, which
may become the controlling factors in the movement.
The Cordilleran ice-sheet 2 is less simply defined. Much of it occu-
pied a plateau hemmed in by mountains, and plateau glaciation was
complicated by extensive mountain glaciation of alpine type. In
some sense, the whole Cordilleran ice-sheet was the product of a con-
fluence of mountain glaciers deploying on the intervening plateau;
but there appears to have been plateau glaciation not solely dependent
on contributions of ice from the mountains. The southerly lobes of
1 Dawson, G. M., Ann. Kept. Geol. Surv. of Can., Vol. II, 1886, pp. 56-58 R.
2Dawson, Ann. Geol., Vol. VI, p. 162, Geol. Surv. of Can., 1888, and Trans.
Roy. Soc. of Can., Vol. VIII, Sec. IV; Tyrrell, Geol. Surv. of Can., 1890, E, pp. 1-240,
and McConnell, idem, D, pp. 24-28.
THE PLEISTOCENE OR GLACIAL PERIOD. 333
the complex body of ice crossed the boundary of Canada, and encroached
somewhat on the United States in the Flathead, Kootenay, Columbia
Okanagon, and Colville valleys. The northern lobes descended the
valleys tributary to the Yukon, but, so far as now known, did not
cross the Canadian boundary into Alaska. It is not known that the
Cordilleran plateau glacier escaped the Rockies to the east, or even
sent tongues through their gaps in the more southerly latitudes of
Canada, though glaciers formed on the mountains crept out on the
western borders of the plains. In the more northerly uninvestigated
latitudes, where the mountains are lower and the gaps deeper and broader,
the descent of ice from the plateau on the west to the plains on the
east is not improbable. On the west, the plateau ice-cap seems to
have sent tongues of ice through the gaps in the coast ranges at many,
points, and to have discharged thence into the Pacific. Though ham-
pered by its environment, the Cordilleran ice-sheet seems to have
conformed to the habit of the Larbradorean and Keewatin sheets in
expanding chiefly to windward. If the whole glaciation, plateau and
alpine, be regarded together, the westward movement of the Cor-
dilleran complex was perhaps even more pronounced than that of
the Keewatin and Labradorean.
Mountain Glaciation. — In Alaska, mountain glaciation was strongly
developed on the ranges adjacent to the Pacific, particularly on the
side next to the ocean. On the north side, the ice pushed well out
from the higher mountains, but did not reach the Yukon. Some
ancient glaciation has recently been discovered on the divide between
the Yukon and the Arctic Ocean, but with this, and perhaps some
undiscovered exceptions, the plains of Alaska seem to have been free
from glaciation even at the stages when the waters of the Ohio and
the Missouri were being turned from their courses by encroaching
ice-sheets, 2000 miles farther south. In view of these and other sin-
gular features of distribution, the localization of the ancient glacia-
tion becomes one of its most significant problems.
South of the continuous Cordilleran glaciation of Canada, local
glaciers were widely distributed from the Rockies on the east to the
Sierras and Olympics on the west, while on the south, within the United
States, they appeared in New Mexico, Arizona, and southern Cali-
fornia. Within this broad area, the deployment of ice was greatest
at the north. Of glaciation in the mountains of Mexico little is known.
GEOLOGY.
The ice of the Puget Sound region 1 came from three sources : the smallest
part came from the Olympics on the west; another and larger part from the
Cascades to the east, while the third and largest part came from the north. This
northern glacier sent a branch westward into the strait' of Juan de Fuca, as well
as one south into Puget Sound. The southern edge of this Puget ice sheet lay
south of Tacoma and Olympia.
East of the Cascades also, glaciation was extensive. As already noted great
tongues of ice, altogether beyond the size of valley glaciers, descended from
the north into the basins of the Okanagon,the Columbia, and the Colville Rivers.2
Glaciation was also widespread in northern Idaho and northwestern Montana.
From the Rocky mountains of the latter state, mountain glaciers descended and
spread for miles on the plain to the east. Just south of the national boundary,
the drift from the Keewatin ice-sheet overlaps that from the mountains.3 Far-
ther south, the extension of the ice east of the mountains was less. Although
they have not all been well studied, it is safe to say that all the principal moun-
tains of Montana, Wyoming, Idaho, Oregon, and Washington harbored glaciers,
some of which were very large. In the Yellowstone Park, in the eastern part
of the mountains, glaciation was so extensive as to belong to 'the ice sheet,
rather than the valley glacier type. The aggregate number of glaciers which existed
in these northwestern states has never been determined, but it must have risen
into the thousands.
The glaciers of the Bighorn mountains of Wyoming * (Fig. 471) were per-
haps typical for those of the lesser ranges in this section of the United States.
The glaciers of this range were numerous, the longest being about 17 miles in
length. None of them, however, reached the surrounding plains.
Farther south, in Colorado, the Front range 5 was more or less generally
glaciated for a width of 16 miles in latitude 40°, while the Park range was gla-
ciated somewhat generally over an area 60 miles long by 10 miles wide. Gla-
ciation in the Medicine Bow range was less extensive. On the east side of the
Sa watch range, an elevation of about 11,000 feet was necessary to produce gla-
ciers.6 Glaciers of great size (one 65 or 70 miles long) existed in the mountains
of southwestern Colorado, where their sources were at altitudes of 11,000 feet
or more.7 In no part of Colorado thus far studied does there appear to have
been a body of ice which extended beyond the limits of a single drainage system.
South of the Front range of Colorado, the eastern ranges of the Rockies were
the site of numerous glaciers as far south as northern New Mexico 8 (lat. 35° 45'),
1 Willis, Tacoma folio, U. S. Geol. Survey.
2 Blackwelder and Garrey, Jour, of Geol. , Vol. IX, pp. 721-724.
3 Calhoun, Jour, of Geol., Vol. IX, p. 718.
4 Blackwelder, Jour, of Geol., Vol. XI, p. 216.
5 King, Geol. Surv. of the 40th Parallel, Vol. I.
6Leffingwell and Capps, Jour, of Geol., Vol. XII, p. 698.
7 Stone, Mono. XXXVII, U. S. Geol. Surv. ; also Hole and Everley, unpublished
data.
8 Salisbury, Jour, of Geol, Vol. IX, 1901.
THE PLEISTOCENE OR GLACIAL PERIOD.
335
where an altitude of nearly 12,000 feet was necessary to give origin to them.
There were also small glaciers on the northeast slope of the San Francisco moun-
FIG. 471 . — Map showing the areas of the glaciers (black areas) of the Bighorn moun-
tains during the last important glacial epoch. (Blackwelder and Bastin.)
tain of Arizona (nearly 13,000 feet, lat. 35° 21'), the most southerly point where
glaciers are known to have existed in the United States.1
1Atwood, Jour, of Geol., Vol. XIII, p 276.
336 GEOLOGY.
In Utah, the greatest glaciers were in the Uinta mountains, where within
an area about 80 miles long by 35 miles wide, there was an aggregate area of
about 1000 square miles of glacier ice.1 Near the crest of the range, only nar-
row divides with steep slopes escaped glaciation. Every considerable valley
of the range whose head had an elevation of 10,000 feet, contained a glacier.
In a few cases, the glaciers descended below the mountains into the open valleys
of the plateau below. The lowest altitude reached by any glacier in the range
was about 6500 feet, and the ice descended on the average about 1000 feet lower
on the south side than on the north, primarily because the catchment basins
on the south slope were larger. Individual glaciers attained a thickness of some
2500 feet. Glaciation was less extensive in the Wasatch mountains, though
the number of glaciers there exceeded 50. The ice was still more limited in the
Bear River mountains of Idaho, just north of the Wasatch range.
Glaciation was of slight extent in the basin ranges of Nevada, though there
were several centers of glaciation among the higher ranges.
There were extensive glaciers in the Sierras. Under favorable conditions,
they descended to an altitude of 4500 feet, and at a few points even lower.2
In few other places in the west were conditions so favorable either for heavy snow-
fall or for ready descent of the ice to low altitudes.
These isolated areas of glaciation are instructive as indicating the extension
of the requisite conditions beyond the limits of the great continental ice-sheets.
If, however, the plains have been elevated since, as the distribution of the Kee-
watin ice and some other facts suggest, the altitude both of the eastern moun-
tains of the Cordilleran system, such as the Bighorns, and of the limits of
glaciation, were probably lower than now at the time of glaciation.
In Wyoming, Colorado, Utah, California, and Washington, the only places
where the glacial history of the western mountains has been studied in detail
the drift is referable to two or more glacial epochs, somewhat widely separated
in time.
Island glaciation. — The Island of Newfoundland seems to have
been a separate area of glaciation. The same was probably true of
Nova Scotia, and evidence is presented by Canadian geologists that
the elevated peninsula between the Bay of Fundy and the lower St.
Lawrence shed ice northward and eastward as well as southward.3
Greenland was glaciated somewhat more extensively than now, but
its glaciers appear never to have extended to the continent, as was
formerly conjectured. A little driftless region in the Inglefield Gulf
1 Atwood, unpublished data; also King, Geol. Surv. of 40th Parallel, Vol. I.
3 California folios, U. S. Geol. Surv.
3 Dawson, J. W. The Canadian Ice Age; Chalmers, Can. Rec. of Sci., 1899, and
Kept. Geol. Surv. of Can., 1885; Murray, Geology of Newfoundland.
THE PLEISTOCENE OR GLACIAL PERIOD. 337
region/ and consonant phenomena elsewhere, indicate only a limited
extension of the ice beyond its present border. The Arctic islands
west of Greenland seem, from present evidence, to have been only
partially glaciated, though the ice extended considerably beyond its
present limits.
Summary. — Reviewing comprehensively the distribution of the
ice, it appears that by far the greatest Pleistocene glaciation was
developed in the northern hemisphere, and . that its most significant
portion was the glaciation of the great lowland areas of northeastern
North America. This glaciation reached its climax of significance
in the deployment of the Keewatin ice-sheet from a low, flat center,
in seeming, but doubtless not real, negligence, or even defiance of
topographic relations, and to some extent of climatic conditions as well.
The Criteria of Glaciation.
So extraordinary a series of phenomena as the repeated burial
of half the plains of North America beneath sheets of ice which spread
southward into mild temperate latitudes, could not be accepted on
other than the most cogent evidence, and it is not strange that the
glacial theory was resisted for half a century, though the iceberg and
other glacio-natant hypotheses urged in its stead seem no more credi-
ble, and far less adequate. But the cumulative force of a vast mass
of evidence, rigorously scrutinized under the promptings of this criti-
cal and reluctant attitude, has become overwhelming, and the days
of reasonable doubt are passed. The decisive evidence lies not only
in a great mass of individual criteria, but in a combination of con-
vergent lines of proof which lend invincible support to one another.
The area which was overspread by ice is covered by a mantle of
clay, sand, and bowlders, which, taken together, constitute the drift.
Some of the drift is stratified (Fig. 472), but more of it is without the
assortment and the definite arrangement which goes with stratification
(Fig. 473). The various lines of evidence which have led to the gen-
eral acceptance of the glacial theory, have to do with (1) the drift,
(2) the surface of the rock which underlies it, and (3) the relations
of the drift to its bed. Some of the principal considerations are the
following:2
1 Chamberlin, Jour, of Geol., Vol. in, 1895.
2 The phenomena pointing to the glacial origin of the drift have become so fa-
338
GEOLOGY.
(1) The constitution of the drift. — One of the striking character-
istics of the drift, taken as a whole, is its heterogeneity, both physical
and lithological. It is made up, at one extreme, of huge bowlders
(Figs. 474 and 475), and at the other of impalpable earthy matter.
Between these extremes there are materials of all sizes, and the pro-
portions of coarse and fine are subject to the greatest variations. Coarse
materials are, on the whole, most abundant in regions of rough topog-
raphy where the underlying formations are resistant, and in the leo
FIG. 472. — A section of stratified drift.
of such situations. Fine materials, on the other hand, are most abun-
dant where the underlying formations, and especially the neighbor-
ing formations in the direction whence the ice came, are weak. The
miliar that it is unnecessary to give extended references to the literature of the sub-
ject. They were emphasized in many of the early publications concerning the drift,
The striae and other scorings of the ice, are elaborated in the 5th Ann. Rept. U. S.
Geol. Surv. The study of the drift from the standpoint of genesis is given in the
Jour, of Geol., Vol. II, pp. 708-724, and 837-851, and Vol. Ill, pp. 70-97, and in
Glacial Geology of New Jersey, pp. 3-33. The geological reports of all the states
affected and of Canada contain descriptions of the phenomena.
THE PLEISTOCENE OR GLACIAL PERIOD.
339
fine material of the drift is made up, in large part, of the same mate-
rials as the gravel and bowlders, but of these materials in a finer
state of subdivision, and often in different proportions. The coarse
materials and the fine are often mixed without trace of assortment
or arrangement.
FIG. 473. — A section of unstratified drift— till or bowlder clay, on bed-rock.
Newark, N. J.
The drift of any locality is likely to contain rock material from
every formation over which the ice which reached that locality had
passed; but the larger part of the drift of any place is composed of
materials derived from formations near at hand. Probably 75% of
the material of the drift has on the average not been moved 50 miles.1
No agent except glacial ice can impress these precise features on
1 The Local Origin of the Drift, Jour, of Geol., Vol. VIII, p. 426.
340 GEOLOGY.
the deposits which it makes, and these are, on the other hand, pre-
cisely the features which existing glaciers are now impressing on their
deposits.
(2) The bowlders and other stones of the drift. — The bowlders
and smaller stones of the unstratified drift possess significant
features. Many of them have smooth surfaces, but they are not
FIG. 474. — " Pilot Rock." A bowlder of basalt near Coule City, Washington. One
of the largest bowlders in America. (Garxey.)
generally rounded. They are often sub-angular, and the wear
which they have suffered has been effected by planing and bruising,
rather than by rolling (Fig. 254, Vol. I, and Figs. 476 and 477). The
plane sides meet one another at various angles, though the angle of
junction is rarely acute. These planed, sub-angular bowlders and
stones are often distinctly marked with one or more series of lines or
scratches, on one or more of their faces. The lines of each series are
parallel, but those of different series may cross at any angle.
By no means all the stones of the drift show striae. They are rarely
THE PLEISTOCENE OR GLACIAL PERIOD.
341
seen on those which have lain long at the surface, and they are much
more common on the less resistant sorts of rock, such as limestone,
than on more resistant ones, such as quartzite. Locally, distinctly
striated stones are rare even in the unstratified drift, and they are
generally rare on the rock fragments of the stratified drift.
No depositing agent except glaciers habitually marks the stones
FIG. 475. — A perched bowlder of Triassic sandstone on the trap-rock of the Palisade
ridge east of Englewood, N. J. Size 12X8X8 feet. This bowlder was probably
carried up by the ice something like 200 feet. (N. J. Geol. Surv.)
which it deposits in this way. Bowlders dropped by icebergs some-
times have such markings, but icebergs are born of glaciers, and the
marks of the striated stones of icebergs were put upon them while
they were still in, or under, the land ice. Water never striates stones
in this way.
(3) Structure of the drift. — The larger part of the drift is unstrati-
fied, but a very considerable part is stratified, often irregularly. The
unstratified drift or till (for some of it the name bowlder-clay is appro*
342 GEOLOGY.
priate), seems to have little orderly arrangement of its parts, yet
it often has a sort of rude cleavage which has been called foliation.
FIG. 476. — Glaciated stones from the drift of northern Illinois. (Photo, by Church.)
^^^^-
FIG. 477. — Glacially faceted and scratched pebbles, remarkable for the number of
planed faces, for the pronounced beveling, etc.; from the Illinois and Michigan
canal, Chicago.
The planes of cleavage are in such relations as to suggest that they
were developed by pressure from above. This is consistent with the
THE PLEISTOCENE OR GLACIAL PERIOD. 343
deposition of the foliated drift beneath a body of ice. The strati-
fied drift shows by its structure that it was deposited by water. This
water doubtless sprang, very largely, from the melting of the ice.
The structural relations of the two great types of drift will be referred
to again, but a conception of these relations is necessary to an under-
standing of the structure of the drift as a whole. Either type of the
drift may overlie the other, or the two may be interbedded; either
may grade laterally into the other, either may abut abruptly against
the other horizontally, or pockets of either may be enclosed in the
other.
The association of the two is often such as to demonstrate their
essential contemporaneity of origin. No agents but glacial ice and
glacio-fluvial waters could have brought about such relations between
the stratified and unstratified drift over such extensive areas.
(4) Distribution of drift. — The distribution of the drift is essentially
the same as that of the ice-sheets and glacial waters; but apart from
this general fact, there are several special features to be noted.
(a) The distribution of the drift is measurably independent of topog-
raphy within the area of its occurrence. Even in closely associated
localities, and outside the higher mountain areas, its vertical range
is as great as the relief of the surface itself. Within the limits of the
state of New York, for example, it ranges from sea-level to the tops
of the Adirondacks, nearly 5000 feet above. Within the area of its
occurrence it is generally found in valleys and on hills, and on plains,
plateaus, and mountains, indiscriminately, though not usually in
equal amounts, (b) The drift is sometimes so disposed as to make
the surface much rougher than it would be otherwise, and some-
times so as to give it less relief. This is illustrated by Figs. 478
and 479. (c) The drift is measurably independent of present drain-
age basins, so far as its constitution is concerned. Thus, materials
from one drainage basin are found in the drift of other drain-
age basins so commonly as to make it clear that present divides did
not constitute divides to the ice. (d) Various sorts of material in
the drift at certain points are so related to their sources as to make
it clear that they were carried upwards, sometimes hundreds of feet,
from their original sites, a point which is often readily established
in the case of large bowlders. Glaciers can do this sort of work, under
proper conditions, but water, unaided by ice; cannot, (e) A con-
344
GEOLOGY.
siderable area in southwestern Wisconsin, and the adjacent parts of
Illinois, Iowa; and Minnesota, is without drift. The driftless area 1
of these states is neither notably higher nor lower than its surround-
FIG. 478. — Figure to illustrate the disposition of the drift in such manner as to
increase the relief of the surface on which it lies.
ings, and the agent which produced the drift must have been such
as could avoid this area. Glacial ice seems to be the only agent com-
petent to the result. (/) Stratified drift often extends beyond the
unstratified, in the direction in which the ice was moving, especially
FIG. 479. — Diagram to illustrate (1) the disposition of drift, the drift being thick
in the valleys and thin or absent on the hills; (2) the effect of the drift on topog-
raphy, making it less uneven; and (3) the sharp contact between firm rock
below and the drift above.
in valleys and on low land. This peculiarity of distribution is the
result of running water.
The first five of these points, a-e, make strongly for the conclusion
that the drift is a product of glaciers, while the sixth (/), is consistent
with this conclusion.
(5) Topography of the drift.2 — Among the characteristic features
of the topography of the drift are: (a) Depressions without outlets,
and (6) knobs, hills, and ridges, similar in size to the depressions,
1 WincheU. Ann. Kept. Minn. Geol. Surv., 1876, pp. 35-38; Irving, Geol. of Wis.,
Vol. II, pp. 632-633; Chamberlin, Ann. Kept. Wis. Geol. Surv., 1878, pp. 21-25,
and Chamberlin and Salisbury, Sixth Ann. Kept. U. S. Geol. Surv., 1885, pp. 199-322.
2 This, as well as other characteristics of the drift, is discussed in 3d Ann. Rept.
U. S. Geol. Surv.
THE PLEISTOCENE OR GLACIAL PERIOD.
345
associated with them (Figs. 480 and 481). Many of the depressions
contain standing water. The surface of some parts of the drift, on
FIG. 480. — A sketch of the drift (terminal moraine) topography near Hackettstown,
N. J. (New Jersey. Geol. Surv.)
,;4
^
FIG. 481. — The topography of the drift shown in contours for an area near Minne-
apolis, Minn. Scale approximately a mile to an inch. (U. S. Geol. Surv.)
the other hand, is nearly plane. Neither planeness nor unevenness
can be ascribed exclusively to the stratified nor to the unstratified
346 GEOLOGY.
drift. Either may be rolling, or either may be plane, though the phases
of topography assumed by the two sorts of drift are somewhat unlike.
The significance of the topography of the drift at this point lies
in the fact that no agent of deposition, except glacial ice, makes deposits
of such topography over great areas, in measurable disregard of the
topography of the underlying rock. That glaciers develop such topog-
raphy is shown by the fact that the drift deposited by glaciers in
recent times, has a topography similar to that possessed by the drift.
It is to be noted, however, that no very recent glacial deposits, com-
parable in area to the drift, are now accessible. Negatively, it may
be added that no other agent of deposition except land ice is believed
to be capable of developing such topography as that possessed by
much of the drift.
(6) Thickness of the drift. — The thickness of the drift ranges from
zero to more than 500 feet, and the variations are often great within
short distances. One hill may be composed of drift, while the next
has no more than an interrupted mantle of drift (Figs. 478 and 479).
The drift may be thick on hills and thin in valleys, but more com-
monly the reverse is the case. These facts are of significance in this
connection in that the thickness is often independent of the topog-
raphy of the underlying surface. No agent besides glaciers so habitu-
ally leaves its deposits so unequally distributed, and in such disregard
of preexisting topography.
(7) Contact of drift and underlying rock. — The plane of contact
between the drift and the underlying rock is generally, though not
always, sharply defined, and the surface of the rock is likely to be fresh
and firm (Fig. 482). When this relation is contrasted with that be-
tween the mantle-rock and the underlying formations where there is no
drift (Fig. 489), the conclusion is forced that in the regions of drift
the surface was stripped of all loose debris, and ground down to the
solid rock below, before the drift was left upon it. This is exactly
what glaciers are now doing.
(8) Striation and planation.1 — The rock surface beneath the drift,
and especially beneath the unstratified drift, is frequently polished,
planed, striated (Fig. 482), and grooved (Fig. 483). These features
are widespread throughout the drift-covered area, and they occur
1 7th Ann. Kept. U. S. Geol. Surv., pp. 155-248. An elaborate discussion of this
topic.
THE PLEISTOCENE OR GLACIAL PERIOD.
347
FIG. 482. — Striae on bed-rock, Kingston, Des Moines County, la. (la. Geol. Surv.)
FIG. 483. — Grooves in limestone on Kelley's Island, Lake Erie. The grooves show
by their lack of strict parallelism that different parts of the grooving were accom-
plished at somewhat different times. The foot-rule indicates the scale, and its
shadow defines the groove. (U. S. Geol. Surv.)
348
GEOLOGY
at all elevations where the drift occurs. The markings on the bed-
rock beneath the drift are so like those on the stones of the drift, that
community of origin cannot be doubted.
FIG. 484. — The radiation of striae in the Green Bay glacial lobe, and in the west part
of the Lake Michigan lobe, during the last glacial epoch.
The stria3 on the bed-rock beneath the drift are generally approxi-
mately parallel in any given locality, and tolerably constant in direc-
tion over considerable areas. When large areas are studied, the striae
are sometimes found to be far from parallel. In general, their depar-
THE PLEISTOCENE OR GLACIAL PERIOD. 349
ture from parallelism is according to a definite system, for they radiate
from the centers already named (Fig. 470). Not only this, but there
are systematic radiations of striae within the lobes of ice which char-
acterized the borders of the great ice-sheets at the stages when it
was most influenced by the broad depressions of the Great Lake region
FIG. 485. — Tortuous glacial grooving. The gorge is believed to be due to a sub-
glacial stream, into the channel of which the ice settled down, moulding itself
to the gorge and grooving it. Kelley's Island, Lake Erie. (U. S. Geol. Surv.)
(Fig. 484). The direction of striae corresponds with the direction in
which the drift was transported.
Sometimes stria3 and grooves follow narrow and tortuous gorges
(Fig. 485). Striae are not confined to horizontal or even to gently
inclined surfaces. They occur on steep slopes (Fig. 486), not infre-
quently on the vertical faces of cliffs, and, occasionally, even on the
under sides of overhanging rock masses.
350
GEOLOGY.
Besides the strise, grooves, etc., on the bed rock, there are often
other details of surface which are equally characteristic. Minute
FIG. 486. — Striae on two contiguous surfaces which meet each other at a large angle.
Southeast shore of Kelley's Island, Lake Erie. (U. S. Geol. Surv.)
protuberances of surface often show more wear on one side than on
the other (Fig. 487 and 488). Minute depressions (Fig. 488), show
FIG. 487. — Small protuberances of rock showing the effect of ice wear. Glacial knobs
and trails. The projections consist of chert in limestone. Near Darlington, Ind.
FIG. 488. — Diagram to show the effect of ice wear on slight depressions in the
surface of rock.
analogous features. The significant point in these features is that
the same sides of the protuberances, and the same sides of the depres-
THE PLEISTOCENE OR GLACIAL PERIOD.
351
sions in any given locality, show the greater wear, and indicate the
direction of ice movement. Other markings, such as chatter marks,
distinctive of ice work, are also found on the bed-rock, though less
commonly than striae, grooves, etc,
(9) The shapes of rock hills. — The rock knolls which were left bare
when the ice retreated, often show peculiarities of form and surface
which are distinctive. Like the minute protuberances of surface just
FIG. 489. — Diagrammatic representation of a hill unworn by the ice. The diagram
also shows the irregular contact between the surface earths and the rock below.
referred to, the rock hills of many localities over which the ice passed
were systematically worn more on the side from which the ice approached
(the stoss-side), than on the other (Fig. 490). Bosses of rock
i
FIG. 490. — Diagram to show the effect of glacial wear on such a hill as that shown in
Fig. 488.
which do not show pronouncedly unequal wear often show dis-
tinctive smoothing (Fig. 491). Projecting glaciated knolls of rock,
whether large or small, which show the characters seen in Fig. 492,
are known as roches moutonnees. A succession of roches moutonnees
generally give fairly accurate information as to the direction of ice
movement, even though stria? be not preserved.
Summary. — The characteristics of the drift, as set forth in the
preceding paragraphs, leave little room for random speculation
concerning its origin. From its variable thickness we know that the
force or forces which produced it must have been such as could leave
the drift now in thick bodies and now in thin, over either limited or
extensive areas. From its distribution we know that the force or
forces which produced it were largely independent both of underlying
352
GEOLOGY.
FIG. 491 .—A polished surface of rock in Bronx Park, N. Y. (Willis, U. S. Geol. Surv.)
FIG. 492. — Roches moutonnees.
THE PLEISTOCENE OR GLACIAL PERIOD. 353
rock formations and of topography. From its physical make up we
know that the agency or agencies which produced it must have been
able to carry and deposit, at one place and at one time, materials as
fine as the finest silt or mud, and bowlders many tons in weight, while
they were competent, under other circumstances, to make deposits
of much less extreme diversity. From its lithological make up, and
from the nature of the finer parts of the drift, we know that the drift
forces worked on different sorts of rock, deriving materials from many ;
that they ground some of the materials into a fine earthy powder or
" rock flour, " commonly called clay; that they as a rule derived the
larger part of the drift of any locality from formations near at hand;
and that the materials, even large bowlders, were sometimes carried
up to altitudes considerably above their source. From the structure
of the drift it is concluded that the drift force or forces must have been
capable of producing deposits which were sometimes stratified and
sometimes unstratified, and that the deposition of these two phases
of drift was sometimes contemporaneous and sometimes successive,
the number of alternations sometimes being considerable. From the
stria? on the stones of the drift it is known that the production of the
drift must have involved the action of forces which, under some con-
ditions, were capable of planing and beveling and striating many stones,
especially the softer ones of the unstratified drift, while rounding and
leaving unstriated most of those of the stratified ; but that the agency
or agencies concerned must have been such that under certain cir-
cumstances their activities failed, on the one hand, to leave more than
a very small percentage of the stones of the unstratified drift beveled
and striated, while, on the other hand, they sometimes permitted
the stratification of gravels containing many subangular, plane-faced,
and striated stones, varying in size from pebbles to bowlders. From
the striae on the bed-rock beneath the drift and the unweathered char-
acter of the surface of the rock, it is clear that severe wear was inflicted
on the surfaces over which the drift was spread, while the positions
in which the stri^were developed show that the agency which inflicted
the wear was able to adapt itself to all sorts of surfaces. The gen-
eral parallelism of strise in a limited area, and the systematic departure
from parallelism over great areas, are also significant of the manner
in which they were produced. From the topography of the drift it
is known that the forces which produced it must have been such as
354
GEOLOGY.
were able to develop plane surfaces at some points, surfaces marked
by more or less symmetrical drift-hills, which are measurably inde-
pendent of rock-topography at others, and short, choppy hills, associated
with undrained depressions, in still others.
The true theory of the drift must explain all these facts and rela-
tions. Any hypothesis which fails to explain them all must be incom-
FIG. 493. — Glaciated dome, Tuolumne Valley, Cal.
plete at the least, and any hypothesis with which these facts and rela-
tions are inconsistent, must be false.
Geologists are now very generally agreed that glacier ice, sup-
plemented by those other agencies which glacier ice calls into being,
is the only agent which could have produced the drift. But it is not
to be forgotten that this does not preclude the belief that at various
times and places, in the course of the ice period, icebergs may have
been formed, or that locally and temporarily they played an impor-
tant role. It does not preclude the idea that, contemporaneously with
THE PLEISTOCENE OR GLACIAL PERIOD. 355
the production of the great body of the drift by glacier ice, the sea
may have been at work on some parts of the present land area, modi-
fying the deposits made by ice and ice drainage. Indeed, there is
abundant evidence that such was the fact, for some regions, now covered
by drift, stood lower than now, relative to sea level, when the drift
was deposited, or since. The glacial theory does not deny that rivers
produced by the melting of the ice were an important factor in trans-
porting and depositing drift, both within and without the ice-covered
territory. It does not deny that lakes formed in one way and another
through the influence of ice, were locally important in determining
the character and disposition of the drift. Not only does the glacier
theory deny none of these things, but it distinctly affirms that rivers,
lakes, the sea, icebergs, and pan-ice must have cooperated with glacier
ice in the production of the drift, each in its appropriate way and
measure, and that after the disappearance of the ice and the ice-water,
the wind had its appropriate effect on the drift before it became clothed
with vegetation.
The Development and the Thickness of the Ice-sheets.
The development of glaciers from snow-fields has been discussed
in Volume I, but a few words with reference especially to the develop-
ment and thickness of the ice-sheets of our continent, are here added.
If the expansion of the ice-sheets was due principally to move-
ment from a center or centers, the ice at these centers must have been
prodigiously thick, for in the course of its progress it encountered
and passed over hills, and even mountains, of considerable height.
In the vicinity of elevations which it covered, its thickness must have
been at least as great as the height of these elevations above their
bases. If such elevations were remote from the center of movement,
the ice must have been still thicker at those centers, to afford the
necessary "head."
If the centers of the North American ice-sheets remained the cen-
ters of movement throughout the glacial period, and if the degree of
surface slope necessary for movement were known, the maximum
thickness of the ice could be calculated. It is probable, however,
both that the centers of the ice-sheet did not remain the effective cen-
ters of movement, and that the surface slope necessary for movement
was variable.
356 GEOLOGY.
If the fall of snow toward the margin of the ice-sheet greatly exceeded
that at its center, as it probably did, an infra-marginal belt, rather
than the geographic center of the field, may have controlled the mar-
ginal movement of the ice. With excess of infra-marginal accumula-
tion, the surface slope of the ice would be relatively great from the
zone of maximum accumulation to the edge of the ice, but might
be very slight, or even nil, within it (Fig. 494). Under these circum-
stances, the extension of the ice being due largely to dispersal from
the infra-marginal zone, the maximum thickness of the ice-sheets
might be notably less than if the geographic center remained the effec-
tive dynamic center.
In an ice-sheet like that which was responsible for the drift of North
America, it is probable that all influencing and limiting conditions
which may exist in any ice-sheet were found. The varying pressures
i
FIG. 494. — Diagram to illustrate the surface configuration of a great ice-sheet, accord-
ing to the conception here presented. The central part is relatively flat and the
margins have steep slopes.
and temperatures to which its various parts were subject tended to
produce various degrees of mobility in its mass, and varying degrees
of mobility demanded varying degrees of surface slope in order to
bring about movement. Could the surface slope necessary for move-
ment be determined for any given region, and for any given time during
the glacial period, it does not follow that the same slope was necessary
for the whole ice-sheet, or even that it was necessary for any particular
region, at all stages of its glacial history. Both observation on existing
glaciers and ice-sheets, and considerations of a physical nature, make
it certain, first, that the angle of slope must have decreased with increas-
ing distance from the margin of the ice (that is, with increasing thick-
ness of the ice) until, at the center of the field, it approached zero;
and second, that at the edge of the ice-sheet, where the ice was thin-
nest, the surface slope was greatest.
No sufficient data are at hand for determining with accuracy
the average slope of such an ice-sheet as that which covered our con-
tinent, but something is known of its slope at certain points. Near
THE PLEISTOCENE OR GLACIAL PERIOD. 357
Baraboo, Wis.,1 the edge of the ice at the time of its maximum exten-
sion in that region lay along the side of a bold ridge, the axis of which
was nearly parallel to the direction of ice movement. The position
of the upper edge of the ice against the slope of the ridge is sharply
defined. For the last one and three-fourths miles, its average slope
was about 320 feet per mile. This, it is to be noted, was at the extreme
edge of the ice, where the slope was at a maximum. In Montana,
the slope of the upper surface of the ice for the 25 miles back from
its edge has been estimated at 50 feet per mile.2 Calculations based
on data from New Jersey and adjacent parts of New York, indicate
for this region a slope of about 30 feet per mile3 for the upper sur-
face of the ice when it was there thickest. It is to be noted that the
data for this calculation were drawn from localities which, while
relatively near the edge of the ice-sheet, were still some miles within
it. At first thought, a surface slope of 30 feet per mile does not seem
excessive, for the surface of such a slope would seem to the eye to
be nearly plane; yet even so moderate a slope may lead to very extra-
ordinary conclusions.
The southern limit of drift in Illinois is not less than 1500 or 1600
miles from the center of movement. An average slope of 30 feet per
mile for 1500 miles would give the ice a thickness of 45,000 feet at
a point 1500 miles from its margin, if the slope of the surface on which
the ice rested be disregarded, and this slope was so little as to be of
no great consequence in this connection. This thickness, more than
eight miles, seems incredible. Even an average slope of 10 feet per
mile would give a thickness of nearly three miles at the center of the
ice-sheet. If by reason of relatively great infra-marginal accumula-
tion, the only part of the ice-cap which had any considerable slope
was its marginal part, the surface of the central portion being nearly
flat, so great a maximum thickness would not be demanded.
Nansen4 found that the surface of the ice-sheet of Greenland rose
abruptly at either margin, and less and less rapidly as its summit was
approached. He crossed the ice where it was about 250 miles wide.
On the east side he found a slope of about 220 feet per mile, and on
1 Jour, of Geol., Vol. Ill, p. 655.
'Calhoun, Jour, of Geol., Vol. IX, p. 718.
3 Smock, Am. Jour. Sci., Vol. XXV, 3d Series, p. 339.
•Nansen, The First Crossing of Greenland, Vol. II, p. 465.
358 GEOLOGY.
the west, 142 feet per mile, for the first 1000 meters of ascent. For
the second 1000 meters of rise, the slopes were 93 and 63 feet per mile,
respectively; while for that part of the snowTfield more than 2000
meters high, and more than 50 miles from the east edge and more than
76 miles from the west edge, the slope ranged from 26 to 37 feet per
mile. From these data it is fair to conclude that if the ice-sheet were
much larger, like that of our continent during the glacial period, the
gradient would be still less toward its center.
Stages in the history of an ice-sheet. — The history of an ice-sheet
which no longer exists involves at least two distinct stages. These
are (1) the period of growth, and (2) the period of decadence. If
the latter did not begin as soon as the former was completed, an inter-
vening stage, representing the period of maximum ice extension, must
be recognized. In the case of the ice-sheets of the glacial period, each
of these stages was probably more or less complex. The general period
of growth of each ice-sheet is believed to have been marked by tem-
porary, but by more or less extensive, intervals of decadence, while
during the general period of decadence, it is certain that the ice was
subject to temporary, but to more or less extensive, intervals of recru-
descence.
In the study of the work accomplished by an ice-sheet, it is of
importance to distinguish between these main stages, and, in the last
analysis, to take account of the oscillations of the edge of the ice in
each.
The Work of an Ice-sheet.
Glacial erosion and glacial deposition have been briefly discussed
in Volume I (p. 281-305). It need only be added here that the surface
over which the ice-sheets moved is believed to have had a topography
which had been shaped, so far as details are concerned, by rain and
river erosion, and was covered by a layer of mantle-rock which origi-
nated in the decay of the formations beneath. The ice removed this
mantle of decomposed material, and cut deeply into the undecayed
rock beneath. The best rough measure of the ice erosion is the great
body of drift, much of which is composed of rock debris, which lay
beneath the decayed horizon at the surface. In effecting this erosion,
the ice modified the preexisting topography to some extent, for
weaker terranes were eroded more than resistant ones, and the topog-
THE PLEISTOCENE OR GLACIAL PERIOD. 359
raphy favored more forcible abrasion at some points than at others,
while the ice itself was more effective at some times and places than
at others. One of the results was the development of rock-basins
by the ice-sheets. On the whole, the topographic effect of glacial
erosion was probably to soften the surface contours, without notice-
ably diminishing the relief. The erosive effect of an ice-sheet of large
size is probably greatest toward its edge, but far enough back for the
ice to be thick. The position of the area of greatest erosion probably
shifted with the decline of the ice-sheet.
The second great phase of the work of the ice was the deposition
of the drift. Some of it was deposited while the ice-sheets were grow-
ing, some of it after they had attained their growth and before decay
had begun, and some of it while they were declining. Some of it was
deposited beneath the body of the ice, and some of it at its edge. In
some places, water played an important role in modifying the drift
left by the ice, while in others its influence was nil. The deposition of
the drift altered the topography notably, especially where the drift was
thick and the relief of the underlying rock slight. It is to the inequali-
ties in the thickness of the drift that many of the peculiar depressions
and elevations of the surface of the drift are chiefly due. Erosion
and the deposition of the eroded material are then the two great
results of an ice invasion, so far as the solid part of the earth is con-
cerned. The effects on life will be considered later.
The drift formations fall chiefly into three categories, namely
(1) those made directly by the ice (unstratified), (2) those made by
ice and water conjointly (stratified, but stratification often irregular),
and (3) those made by water emanating from the ice (stratified, often
with cross-bedding). To these deposits should perhaps be added,
(4) deposits made by floating ice derived from glaciers, and (5) the
eolian deposits to which the glacial deposits gave origin.
Formations made by the Ice-sheets.1
The ground moraines, the terminal moraines, and the lateral moraines
are the principal types of drift deposited by the ice directly. Of these,
the ground moraines are by far the most extensive, while in connec-
1 Jour, of Geol., Vol. II, pp. 517-538, and Inst. Geol. Congr. Compt. Rend., 5th
Session, 1893; also McGee, idem.
360 GEOLOGY.
tion with the ice-sheets, lateral moraines (Vol. I, p. 302) have little
development.
The ground moraine (Vol. I, p. 301) is the most familiar and wide-
spread phase of drift, and its features are those usually given as charac-
teristic of drift in general. The ground moraine (or till) is nearly co-ex-
tensive with the ice-sheets themselves, though it failed to be deposited
in some places, and it has been removed, or buried by stream deposits,
in others. The ground moraines of the North American ice-sheets
are thickest far from the centers of the ice-fields, in a broad infra-
marginal belt extending from central New York through central and
northern Ohio, Indiana, Illinois, Iowa, Minnesota, and Dakota, and
northward to an unknown limit in Canada.1 Towards the centers
of the ice-fields, and often near their outer borders, the drift is thin,
because in the former place it was never left, and in the latter often
because it has been removed by erosion.
The topography of the ground moraine varies within wide limits.
It may be nearly plane, but is more commonly gently undulatory,
the undulations involving gentle sags and swells. The former are often
the sites of marshes, ponds, and lakes (right-hand part of Fig. 498).
The sags and swells frequently show a tendency to elongation in the
direction of ice movement. The hills of ground moraine sometimes
take on rather definite elongate shapes, with their longer axes in the
direction of ice movement and two to ten times the shorter. Such
hills of till are drumlins (Figs. 495 and 496). They are the most dis-
tinctly defined aggregations of ground moraine. Many hills and
swells of the ground moraine, however, are not drumlins. Drumlins
find their most pronounced development in the United States in east-
ern Wisconsin, where their number has been estimated at 10,000 (Buell),
and in central and western New York,2 though they are not confined
to these localities. The drumlins of New York (Fig. 496) are, in gen-
eral, much longer than those of Wisconsin.
The origin of drumlins has been much discussed, but there is,
as yet, no generally accepted conclusion, and the subject is still
under active inquiry. Opinion is chiefly divided between the views,
1 For descriptions of the ground moraine in various regions, see State Reports.
2 For the topography of the drumlins, see the following topographic sheets U. S.
Geol. Surv. : Wisconsin: Sun Prairie, Watertown, and Waterloo; New York: Oswego,
Palmyra, Clyde, Brockport, and Weedsport; Massachusetts: Boston.
THE PLEISTOCENE OR GLACIAL PERIOD.
361
(1) that they were accumulated beneath the ice under special con-
ditions, and (2) that they were developed by the erosion of earlier
aggregations of drift, much as roches moutonnees are developed.
Under the first of these general views, it has been suggested (1) that
the bars of rivers give the clue to the origin; (2) that protuberances
of rock gave occasion for the lodgment; (3) that the balance between
load and strength of movement furnishes the key to their explanation,
FIG. 495. — Drumlins shown in contour near Sun Prairie, Wis. (U. S. Geol. Surv.)
a slight but not excessive overload being the condition necessary for
their development; and (4) that they may be, in some way, connected
with longitudinal crevasses.1
1 Papers on Drumlins. — Hall, Geol. Fourth District of New York, 1873, pp. 414-5;
Lapham, Smiths. Contr. for 1855; Shaler, Proc. Bos. Soc. Nat. Hist. 1870, pp. 196-204;
C. H. Hitchcock, ibid, Vol. XIX (1876), pp. 63-67; Matthew, Geol. Surv. of Can.,
Kept. 1877-79, pp. 12-14, EE; Upham, Proc. Bos. Soc. Nat. Hist. 1879, pp. 220-234,
ibid., Vol. XXIV (1889), pp. 228-242, Geol. of N. H., Vol. Ill (1878), Am. Geol.
Vol X (Dec. 1892), pp. 339-360, and Bull. Geol. Soc. Am. Vol. Ill (1892), p. 142;
Stone, Proc. Bos. Soc. Nat. Hist., Vol. XX (1880), p. 434,; Johnson, Trans. N. Y.
Acad. Sci., Vol. I (1882), pp. 78-89, and N. Y. Acad. Sci., Vol. II, pp. 249-266;
Chamberlin, Geol. of Wis., Vol. I (1883), p. 283, Proc. Am. Assoc. Adv. Sci. 1886,
p. 195, Third Ann. Kept. U. S. Geol. Surv., 1883, p. 306, and Jour, of Geol., Vol. I,
p' 255-267; Dana, Am. Jour. Sci., Vol. XXII (1883), pp. 357-361; Davis, ibid.,
Vol. XXVIII (1884), pp. 407-416; Chalmers, Geol. of Can. Rept. 1881-9, Vol. IV,
p. 23; Salisbury, Geol. Surv. of New Jersey, Rept. 1891, p. 74, and Glacial Geology of
362
GEOLOGY.
A terminal moraine (Vol. I, pp. 299-301) is made where the edge
of the ice remains nearly stationary in position for a considerable
period of time. In constitution it may be very like the adjacent ground
1
w^
FIG. 496. — Drumlins shown in contour near Clyde, N. Y. (U. S. Geol. Surv.)
moraine, though there is often a larger proportion of stratified drift
associated with it. In topography it is somewhat distinctive. It
New Jersey, 1902; Lincoln, Am. Jour. Sci., Vol. XLIV (1892), pp. 293-6; Tyrrell,
Bull. Geol. Soc. Am., Vol. I (1890), p. 402; Barton, Am. Geol., Vol. XIII (1894), p.
224; Frank Leverett, Monogrs. XXXVIII and XLI, U. S. Geol. Surv., and Russell,
Amer. Ceol., Vol. XXXV (1905), p. 177.
THE PLEISTOCENE OR GLACIAL PERIOD.
363
sometimes constitutes a more or less well-defined ridge, though this
is not its most distinctive feature, since its width is generally great,
relative to its height. A moraine 50 or even 100 feet high and a mile
wide is not a conspicuous topographic feature, except in a region
of unusual flatness. In such situations terminal moraines some-
times constitute important drainage divides.
The most distinctive feature of a well-developed terminal moraine
FIG. 497. — Terminal moraine topography near Oconomowoc, Wis. (Fenneman.)
does not lie in its importance as a topographic feature, but in the details
of its own topography. Its surface is often characterized by hillocks
and hollows, or by interrupted ridges and troughs, following one another
in rapid succession, and without apparent order in their arrangement
(Figs. 497 and 498). The hollows and troughs are often without out-
lets, and are frequently marked by marshes, ponds, and lakes where-
ever the material constituting their bottoms is sufficiently impervious
to retain the water falling and draining into them. The shape and
abundance of round and roundish hills, and of short and more or less
serpentine ridges, often closely huddled together, have locally given
rise to such descriptive names as the " knobs/ ' " short hills/' etc.
364
GEOLOGY.
THE PLEISTOCENE OR GLACIAL PERIOD. 365
But it is the association of the " knobs " or " short hills " with the
" kettles/7 and not either feature alone, which is especially character-
istic of terminal moraine topography.
The " knobs " vary in size, from low mounds but a few feet across,
to considerable hills half a mile or more in diameter, and a hundred
feet or more in height. If they attain such heights while their bases
are small, their slopes are steep. Not rarely they are about as steep
as the loose material of which they are composed will lie.
The " kettles " are the counterparts of the elevations. They may
be a few feet, or many rods, or even furlongs in diameter. They may
be so shallow that the sagging at the center is scarcely observable,
or they may be scores of feet in depth. If steep-sided depressions
are closely associated with abrupt hillocks, the topography may be
notably rough, and the total relief within a few rods may be nearly
equal to the total height of the moraine above its surroundings. The
topography of the terminal moraine is often strongly developed, even
where the moraine as a whole does not appear as a distinct ridge.1
The surface of the terminal moraine, where well developed, is gen-
erally rougher than that of the ground moraine, but more because
the sags and swells are of smaller area and steeper slopes than because
the relief is notably more. It is not to be understood, however, that
this peculiar topography always affects terminal moraines, or that
it is strictly confined to them. The elevations and depressions of the
moraine may grade from strength to weakness, and locally may even,
disappear, while features closely simulating those characteristic of ter-
minal moraines are sometimes found in other parts of the drift.
Development of terminal moraine topography. — The first condi-
tion for the development of a terminal moraine is that the edge of
the ice remain approximately stationary in position for a time suffi-
ciently long for the submarginal accumulation to become sensibly
thicker than the drift within or without. If the margin of the ice
remained constant in position over a region of uniform topography
during the formation of a terminal moraine, and if the ice bore equal
amounts of material at all points along its margin, the terminal moraine
would be developed with some regularity. It would be about as high
1 The terminal moraines of various regions are described in various state
reports and in various reports of the U. S. Geol. Surv., especially the 3d Ann. Kept.,
and in Monographs XXXVIII and XLI.
366 GEOLOGY.
and about as wide at one point as at another. If the margin remained
constant in position, but bore unequal amounts of material at different
points, the moraine would be unequally developed. Where there
was much material it would be higher and probably wider than where
there was but little. Irregularity of height and width would thus be
introduced by reason of the unequal amounts of material at different
parts of the ice edge.
If, instead of remaining stationary, the margin of the ice moved
alternately backward and forward within narrow limits, the effect
would be to spread the moraine by widening the zone of submarginal
accumulation. If, during the oscillation of the margin, it remained
stationary either during or after its minor recessions or advances, or
both, subordinate ridges would be developed, marking the positions
of the several halts. If the edge of the ice remained parallel to itself
as it advanced and receded, these subordinate ridges would be parallel,
and each a miniature terminal moraine. But if while the edge of the
ice was carrying unequal amounts of material, its edge oscillated
unevenly, with halts, that is, if recessions and advances were unequal
at different points, the several subordinate ridges formed at the vari-
ous positions of halt would not be parallel, and would not be equal
in height or width, and no one of the ridges would be uniform in size
throughout its course. Adjacent ridges might touch each other at
some points, and be separate from each other by considerable intervals
at others. The result would be a series of interlocking moraine ridges
of variable heights and widths, constituting a " tangle " of moraine
hills and ridges, with depressions of various shapes and sizes. In this
way it is believed many of the characteristic hills and hollows of ter-
minal moraines arose. If marginal masses of ice were detached from
the main body during its temporary recessions, they might subse-
quently be buried by deposits of drift. Later, when these buried
ice-blocks melted, a kettle-like depression, marking the site of the
buried ice block, would result. Thus would be added another ele-
ment of complexity in the topography of the terminal moraine. Such
surface debris as there may have been on the ice while the edge was
stationary was continually being dropped (dumped) at the edge of
the ice. If the edge of the ice oscillated, this drift would have been
scattered over a zone as wide as the zone of oscillation. Wherever
and whenever the edge remained perfectly stationary, there was a
THE PLEISTOCENE OR GLACIAL PERIOD. 367
tendency for the surface debris to be dumped at the edge along a defi-
nite line. Locally, where the debris dumped was mainly bowlders,
a wall-like ridge (Geschiebewall) was developed in such a position.
Such bowlder-walls have received little emphasis in America, although
they are known to exist at various points.
The ridges and mounds of debris brought to the surface of the ice
near its edge by the upturning layers (Fig. 271, Vol. I) may be a fur-
ther, though very subordinate, element in the development of terminal
moraine topography.1
Where an ice-sheet or a glacier halted in its retreat, its edge or
end remaining in a constant or nearly constant position for a suffi-
ciently long period, a terminal moraine was developed. Such a ter-
minal moraine is often called a recessional moraine. Some caution
is needful in the use of this term lest it be the occasion of misinter-
pretation. While formed in a general time of retreat, some of these
later moraines represent appreciable advances, while others appa-
rently represent halts merely, and some may possibly signify only
an unusually slow rate of recession, by reason of which a deeper accu-
mulation of drift took place. The not uncommon impression that a
terminal moraine is one which, by its very name, marks the terminus
of the drift, is fundamentally erroneous and very objectionable, since
the word terminal merely relates to the terminus of the ice which formed
the moraine, and is contrasted with medial and lateral. It has no
relation to the stage of advancement or of retreat of the terminus
of the ice. No one moraine marks the border of the drift throughout
its entire extent, and confusion arises from the attempt to substitute
the border of the drift, for the edge of the ice, in the significance of the
word terminal.2
1 Jour, of Geol., Vol. IV, 1896, pp. 793-800.
2 References on terminal moraines: Whittlesey, Smiths. Contr., 1866; Dawson,
G. M., Q. J. G. S., Nov. 1875, p. 614; Chamberlin, Trans. Wis. Acad. Sci., Vol. IV,
(1876-7), pp. 201-234, Proc. Int. Cong. Geologists, Paris, 1878, Third Ann. Kept.
U. S. Geol. Surv., 1881-2, pp. 291-402, and Amer. Jour. Sci., Vol. XXIV (1882),
pp 93_97; Irving, Wis. Geol. Surv., Vol. II (1877), pp. 615-634; Cook and Smock,
New Jersey Geol. Surv., 1876-7, and 1877-8; Hitchcock, N. H. Geol. Surv., Vol. Ill
(1878), pp. 218, 230-236, 246, 301-5, 337; Upham, Amer. Jour. Sci., 1879, pp. 81-92,
197-209, Minn. Geol. Surv., Vol. I (1884), Can. Geol. Surv., Vol. IV, 1889, pp. 44-5 E,
Proc. Amer. Assoc. Adv. Sci., Vol. XXXII (1883), pp. 213, 232, and Kept. Minn.
Geol. Surv., 1880, pp. 281-356; Sweet, Wis. Geol. Surv., Vol. Ill (1880), p. 384;
White, I. C., Penn. Geol. Surv., 1880, p. 26; Winchell, N. H., Ohio Geol. Surv., Vol. II,
368 GEOLOGY.
FLUVIO-GLACIAL DEPOSITS.
The phenomena of existing glaciers afford warrant for the view
that the waters arising from the melting of the ice-sheets organized
themselves, to a greater or less extent, into streams l before they left
the ice (Vol. I, p. 280). This was doubtless true to a larger extent
near the edge of the ice than farther back. Ultimately, the subglacial
and englacial waters escaped from the ice. When this took place,
the conditions of flow were more or less rapidly changed, for instead
of being confined to tunnels, under hydrostatic pressure, as hereto-
fore, the streams now followed the laws governing normal river-flow.
When the streams entered standing water, as was sometimes the case,
the standing water modified the results which the running water would
otherwise have produced (Vol. I, pp. 305-307). The water issuing
from the ice thus made deposits in several classes of situations.
(1) At the edge of the ice. — Where subglacial streams flowed under
" head/' the pressure was relieved when they escaped from the ice,
and diminution of velocity and deposition of load were the common
results. Since these changes took place at the edge of the ice, aqueous
deposits were sometimes made in this position, in immediate con-
tact with the ice itself. The edge of the ice was probably more or
less ragged, and the deposits made by the issuing waters were some-
times left in the reentrant angles and marginal crevasses. When
the ice against which the river-deposited debris was banked, melted,
the gravel, sand, etc., assumed the form of mounds, hillocks, and short
ridges. Such knobs, hills, and ridges are kames (Fig. 499). Kames
may be developed in other ways, but they are primarily phenomena
of the margin of the ice, developed by running water (the active agent)
in association with ice (the passive partner).
In position, kames have some relation to terminal moraines, and
there is perhaps no situation in which they are so numerous as in asso-
Minn. Geol. Surv., Vol. I (1884); Lewis and Wright, Second Geol. Surv. Pennsyl-
vania, Kept. Z, 1882; Tyrrell, Amer. Geol., Vol. VIII, pp. 19-28 (1891); Bell, Bull. G. S.
A., Vol. I., pp. 303, 306; Salisbury, Glacial Geology of New Jersey, pp. 93-100 and
231-260; Leverett, Monogrs. XXXVIII and XLI., U. S. Geol. Surv.; Todd, Bulls.
144 and 158, U. S. Geol. Surv., 1896 and 1899, and Am. Jour. Sci., 4th ser., Vol. VI,
pp. 489-477, 1898. See also State Geological Reports of States affected by the ice-
sheets.
1 The general topic of ice drainage is discussed in Glacial Geology of New Jersey,
p. 113 et seq., and Jour, of Geol., Vol. IV, p. 950 et seq.
THE PLEISTOCENE OR GLACIAL PERIOD. 369
elation with such moraines. Many of the conspicuous peaks, knobs,
and hills of the latter are, individually, kames. Belts of kames having
the general position, relations, and significance of terminal moraines
are called kame moraines.1 Kames occasionally attain a height of
100 feet or more, but heights of 20 to 40 feet are much more common.
The stratification of the sand and gravel of which the kames are
Scale.
j 4 1 MILE.
FIG. 499. — A group of kames shown in contour; near Connecticut Farms, N. J.
(N. J. Geol. Surv.)
chiefly composed was often irregular at the outset, and was subject
to disturbance with every movement of the edge of the ice, so long
as the ice and kames were in contact. The effects of the crowding
of the ice are often distinctly seen in the disturbed and crumpled con-
dition of the planes of stratification. The stratification was subject
to still further disturbance when the ice melted, for in many cases
1 Kept. State Geol. of N. J., 1892, p. 93, and Glacial Geology of N. J., p. 117.
370 GEOLOGY.
the kame material, originally deposited against steep faces of the ice
must have slumped notably.
Much of the material entering into the make-up of kames had not
been carried far, and was, therefore, not well water-worn. Not rarely
its constituents retain glacial striae. These characteristics of the
material of kames gave rise to the descriptive designation " hillocks
of angular gravel and disturbed stratification." 1
Kames, developed at the edge of the ice during its advance, were
over-ridden or destroyed as the ice pushed on over them; but kames
developed at the edge of the ice at its most advanced stage and during
its retreat, were not destroyed by the ice, and many of those formed
in such situations by the later ice-sheets, and especially by the last,
are still in existence.2
In regions of strong relief, ice often occupied deep valleys, after
it disappeared from the intervening ridges. In such situations the
ice sometimes seems to have lost vigorous motion, and drainage along
its sides gave rise to deposits of stratified drift (Fig. 500), which after
»Am. Jour. Sci., Vol. XXVII, 1884, p. 378.
2 References touching Kames and Eskers: Hitchcock, Elementary Geology, 1857,
pp. 260-3; Shaw, 111. Geol. Surv., Vol. V (1873), pp. 107-110; Minn. Geol. Surv.,
Vol. I (1884); Newberry, Geol. Surv., Ohio, Vol. II (1874), pp. 41-6; Vol. Ill,
(1878), pp. 40-2; Lindemuth, ibid., p. 503; Upham, Proc. Amer. Assoc. Adv. Sci.,
1876, pp. 216-225, Amer. Jour. Sci., Vol. XIV (1877), p. 459, Geol. of N. H.. Vol. Ill
(1878), pp. 3-176, and Amer. Geol., Vol. VIII (1891), p. 321; Chamberlin, Geol.
of Wis., Vol. II (1877), Third Ann. Kept. U. S. Geol. Surv., 1881-82, p. 299, and
Amer. Jour. Sci., Vol. XXVII (1884), pp. 378-390; Cook, N. J. Geol. Surv. (1888),
p. 116; Wright, Proc. Bos. Soc. Nat. Hist., Vol. XX (1878-80), pp. 210-220, and
Ice Age in North America; McGee, Proc. Amer. Assoc. Adv. Sci., Vol. XXVII (1878),
pp. 198-231, and Eleventh Ann. Kept. U. S. Geol. Surv., 1889-90; Stone, Proc. Bos.
Soc. Nat. Hist., Vol. XX (1880), pp. 430-469, and Mono. XXXIV, U. S. Geol. Surv.;
Dana, Amer. Jour. Sci., Vol. XXII (1881), pp. 451-468, Vol. XXIII (1882), pp. 179,
360, and Vol. XXIV (1882), p. 98; Hitchcock, Proc. Amer. Assoc. Adv. Sci., Vol.
XXXI (1884), p. 388; Lewis, Kept. State Geol. Surv. Penn.,Rept. Brit. Assoc. Adv.
Sci., 1884, p. 720, and Proc. Phil. Soc. Nat. Hist., 1885, pp. 157-173; Shaler, Proc.
Bos. Soc. Nat. Hist., Vol. XXIII (1884), pp. 36-44, Ninth Ann. Rept. U. S. Geol.
Surv. (1887-88), pp. 549-550, and Bull. Mus. Comp. Zool, Vol. XVI, pp. 203-5;
Wmchell, Minn. Geol. Surv., Vol. I (1884), pp. 388, 665; Ells, Ann. Rept. Geol. Surv.
Can. (1885), p. 653; Hoist, Amer. Nat. , Vol. XXII (1888), p. 589; Crosby, Physical
History of Boston Basin, 1889; Chapin, Trans. Meriden Sci. Assoc., Jan. 1891; Salis-
bury, Ann. Rept. N. J. Geol. Surv., 1891, pp. 89-92, and Glacial Geol. of N. J., 1902;
Russell, Amer. Geol., Vol. XII (1893), p. 232; Gulliver, Jour. Geol., Vol. I (1893),
pp. 803-812; Davis, Bull. Geol. Soc. Amer., Vol. I, pp. 195-202, and Proc. Boston Soc.
Nat. Hist., Vol. XXV., pp. 478-499; Bouve", ibid., p. 173.
THE PLEISTOCENE OR GLACIAL PERIOD.
371
the melting of the ice, had somewhat the form of terraces, while their
slopes and upper surfaces had something of the topography of kames.
FIG. 500. — Diagram to illustrate deposition between stagnant or nearly stagnant
ice, and the wall of the valley in which it lies.
Such terraces have been called kame terraces1 (Fig. 501). This type
of stratified drift finds abundant illustration in the Appalachian moun-
tain region and in New England.
FIG. 501. — Diagram to illustrate kame terraces. ABC represents the stratified drift
of the kame terraces which are underlain by ground moraine. Till also covers
the valley bottom.
(2) Beyond the edge of the ice. — When the waters issuing from the
ice found themselves in valleys, and when they possessed sufficient
load and not too great velocity, they aggraded their valleys, developing
valley trains,2 which often extended far beyond the unstratified drift
with which they were contemporaneous. Valley trains are usually
associated with stout terminal moraines (Fig. 502). A protracted
FIG. 502. — Diagram to illustrate the profile of a valley train and its relation to the
terminal moraine in which it heads.
stationary stand of the ice-edge is as necessary for great aggradation
of the valley below, as for the development of the terminal moraine.
Salisbury, op. cit., pp. 156 and 121-124 respectively.
2 3d Ann. Kept. U. S. Geol. Surv., and Jour, of Geol., Vol. I, p. 534.
372 GEOLOGY.
Valley trains often sustain significant relations to recessional moraines,
as suggested by Fig. 503.
Where the water escaping from the ice spread over a plain instead
of being concentrated in valleys, the deposits took on a form more
like that of alluvial fans. By union, these fans often became exten-
sive, and are known as outwash plains, overwash plains, moraine plains,
frontal aprons, etc. They differ from valley trains much as alluvial
fans differ from flood-plain deposits.
When the water which issued from the ice entered standing water
it tended to develop deltas. Where the edge of the ice was long sta-
tionary, the deltas often attained great size. They sometimes merged
laterally as alluvial fans do, giving rise to compound deltas, or
FIG. 503. — Diagram to illustrate the relations of imperfect valley trains to recessional
moraines. The heads of the several trains are at 1, 2, 3, and 4. Examples of
this relation are common in northern New Jersey.
subaqueous outwash plains.1 Many such deltas are known about
extinct lakes in the glaciated area of the United States, and about
the borders of existing lakes, the levels of which have been lowered.
The iceward edges of the deltas, like the iceward edges of outwash
plains and valley trains, were sometimes in contact with the ice, and
took on a kame-like phase. Deltas were also built into the sea at
some points.2
Many of the valley trains, outwash plains, and deltas which developed
beyond the edge of the later, and especially the last ice-sheet during
the time of its maximum advance or during its retreat, are still well
enough preserved to be readily identified, but they have little repre-
sentation among the deposits left by the earlier sheets of ice. If they
were well developed in the earlier glacial epochs, as they doubtless
were in some cases, but apparently not in others, they have been largely
removed by subsequent erosion. Valley trains, outwash plains, deltas,
etc., developed during the advancing stage of an ice-sheet were over-
1 The deltas about the extinct lake Passaic are an illustration. Ann. Kept. State
Geol. of N. J., 1893, and Glacial Geol. of N. J.
2 Stone, Mono. XXXIV, U. S. Geol. Surv., p. 371.
THE PLEISTOCENE OR GLACIAL PERIOD. 373
ridden and generally destroyed or obscured by the further advance
of the ice.
Gradational types, pitted plains, patches of gravel and sand.1 — Out-
wash plains sometimes depart from planeness by taking on some meas-
ure of undulation of the sag and swell (kame) type, especially near
their iceward edges. The same is often true of the heads of valley
trains. The heads of valley trains and the inner edges of outwash
plains, it is to be noted, occupy the general position in which kames
are commonly formed, and the undulations which often affect these
parts of the trains and plains, respectively, are probably to be attrib-
uted to the influence of the ice itself. Valley trains and outwash
plains, therefore, at their upper ends and edges, respectively, may
take on some of the features of kames, and either may head in a kame
area.2
Occasionally a morainic plain, or stratified drift in the general
position of a morainic plain, is affected by numerous sags without
corresponding elevations. This topographic type has received the
name of pitted plain. The sags, in many cases at least, appear to be
intimately connected with the ice-edge, and so to be marginal phe-
nomena.
At many points near the edge of the ice during its maximum stage
of advance, there probably issued small quantities of water not in
the form of well-defined streams, bearing small quantities of detritus.
These small quantities of water, with their correspondingly small
loads, did not develop considerable plains of stratified drift, but small
patches instead. Such patches have received no special designation.
When the waters issuing from the edge of the ice were sluggish,
whether they were in valleys or not, the materials which they carried
and deposited were fine instead of coarse, giving rise to deposits of
silt or clay, instead of sand and gravel.
In the deposition of stratified drift beyond the edge of the ice,
the latter was concerned only in so far as its activities helped to supply
the water with the necessary materials.
(3) Beneath the ice. — Subglacial streams seem sometimes to have
deposited gravel and sand in their channels. When the waters were
1 Geol. of Wis., 1873-1880; Davis, Bull. Geol. Soc. Am., 1890, Vol. I, p. 195;
Gulliver, Jour, of Geol., Vol. I, p. 803, and Glacial Geol. of N. J.
2 Ann. Kept. State Geol. of N. J., 1892, p. 94.
374
GEOLOGY.
not confined to definite channels, their deposits probably took on the
form of irregular patches of silt, sand, or gravel; but where definite
streams were confined to definite channels, their deposits were cor-
respondingly restricted. When the channels remained constant in
position for a long time, the aggradation may have been considerable.
In so far as the channel deposits were made near the edge of the ice
during the time of its maximum extension or retreat, they were likely
to remain undisturbed during its melting, after which they stood out
FIG. 504. — An esker in Scandinavia, locality unknown.
as ridges. These ridges of gravel and sand are known as osars or eskers
(Figs. 504 and 505). It is not to be inferred that eskers never orig-
inated in other ways, but it seems clear that this is one method, and
perhaps the principal one, by which they came into existence.
Eskers early attracted attention, partly because they are rela-
tively rare, and partly because they are often rather striking topo-
graphic features. They are often conspicuous, not so much because
of their height, as because of their abrupt slopes and their even and
marrow crests. They may be ten or several times ten feet high, but
their crests are generally no more than a few feet wide. They are,
for example, often so narrow, and their slopes so steep, that two wagons
could with difficulty pass each other on their tops. The angle of their
THE PLEISTOCENE OR GLACIAL PERIOD. 375
slopes is about the angle at which the drift will lie. Where they cross
marshes and swamps, as is sometimes the case, they are most con-
spicuous, sometimes resembling railway grades. Eskers no more
than a fraction of a mile in length are more common than longer ones,
but eskers scores of miles long are known. Long eskers sometimes
wind up and down over low elevations and valleys, showing that the
water which made them must have been under great head, if they
FIG. 505. — An esker 10 miles west of Aurora, 111. (Bastin.)
are of strictly subglacial origin. They often lie along the lower slope
of a valley, though distinctly above its bottom. Eskers are likely
to be interrupted at intervals, probably at points where the deposit-
ing waters failed of confinement to definite channels, or their channels
were too constricted, or had too high gradient to permit of deposition.
The best-developed eskers in the United States are in Maine.1
Eskers are made up primarily of stratified gravel and sand. As
in kames, the stratification is often much distorted, probably as the
result of ice pressure. Bowlders are often present in them and on
1 Stone, Mono. XXXIV, U. S. Geol. Surv.
376 GEOLOGY.
their surfaces, showing the presence of the ice during their building.
The bowlders might have been crowded in from the sides, or let down
from the ice above. As in kames, the gravel is often not well rounded.
Eskers often end in kames, and where they are interrupted, the inter-
val is often occupied by kames. Occasionally they end in deltas,
where the constructing stream issued from the ice into a lake, or in
alluvial fans, where the stream issued upon a plain.
Most existing eskers were probably made just before the disappear-
ance of the ice from the region where they occur. Eskers made during
the advance of an ice-sheet were likely to be destroyed at a later time.
Probably most eskers were made by streams flowing essentially parallel
to the direction of the ice movement. The deposits of streams in other
positions would stand much less chance of developing distinct ridges
before being destroyed by the movement of the ice.
It is probable that kames are sometimes developed beneath the
ice. It has been noted that eskers are occasionally interrupted, prob-
ably both where the channels of the subglacial streams suffered con-
striction, and great leakage. It is now to be added that kames are
sometimes developed at the point of interruption. Irregular and
ill-defined patches of sand and gravel, instead of kames, often occur
where the eskers are broken.
(4) Deposits of superglacial and englacial streams. — Superficial and
englacial streams have been supposed to make deposits in their channels.
It has even been conceived that this was the principal mode of origin
of eskers. Against this view, and against the view that superglacial
stream deposits are of consequence quantitatively, stand two facts.
(1) So far as known, the surfaces of ice-sheets are free from drift (apart
from wind-blown dust) except for a fraction (and generally a small
one) of a mile from their edges;1 and (2) superficial streams are, in
general, much too swift to allow of the accumulation of drift in their
channels. The channels of most superficial streams in North Green-
land, even near the edge of the ice where surface debris is abundant, are
free from drift. Judging from the force with which they issue from
the ice, englacial streams are likewise much too swift to allow of depo-
sition along their channels, as a general rule.
Such trivial accumulations of drift as may be made in superglacial
1 Jour, of Geol., Vol. IV, p. 804.
THE PLEISTOCENE OR GLACIAL PERIOD. 377
or englacial channels would ultimately reach the land surface. During
the advance of the ice they would be delivered onto the land, as the
ice which sustained them melted from beneath. They would then
be over-ridden by its further forward motion. During the retreat of
the ice, such deposits, once they reached the land surface, would not
be subsequently destroyed or overridden by it.
Relations of Stratified to Unstratified Drift.1
The general relations of the stratified to the unstratified drift have
already been indicated in a general way. These relations may be
understood, when it is remembered (1) that the edge of each ice-sheet
probably oscillated back and forth, more or less, during both its advance
and its retreat, (2) that there were several ice-sheets over large parts
of the area affected by drift, and (3) that stratified drift was being
deposited at all stages of every ice-sheet, at points (a) beneath the
ice, (6) at its edge, and (c) beyond it.
On the basis of position, existing stratified drift deposits may be
classified as follows:
1. Extraglacial deposits, made by the waters of any glacial epoch
if they deposited beyond the farthest limit of the ice.
2. Supermorainic deposits, made chiefly during the final retreat of
the ice from the locality where they occur, but sometimes by extra-
glacial streams or lakes of an epoch later than that when the subjacent
till was deposited. Locally, too, stratified deposits of an early stage
of a glacial epoch, lying on till, may have failed to be buried by the sub-
sequent passage of the ice over them, and so remain at the surface.
In origin, supermorainic deposits of stratified drift were for the most
part extraglacial (including marginal), so far as the ice-sheet calling
them into existence was concerned. Less commonly they were sub-
glacial, and failed to be covered, and less commonly still (if ever)
superglacial.
3. Submorainic (basal) deposits were made chiefly by extraglacial
waters in advance of the first ice which affected the region where they
occur. They were subsequently overridden by the ice and buried
by its deposits. Submorainic deposits, however, may have arisen in
other ways. Subglacial waters may have made deposits of stratified
1 Jour, of Geol., Vol. IV, pp. 948-970.
378 GEOLOGY.
drift on surfaces which had been covered by ice, but not by till, and
such deposits may have been subsequently buried. The retreat of an
ice-sheet may have left rock surfaces free from till, on which the marginal
or extra-marginal waters of the retreating ice, or of the next advancing
ice, may have made deposits of stratified drift. These may have been
subsequently covered by till during a re-advance of the ice in the same
epoch, or in a succeeding one. Still again, till left by one ice-sheet
may have been completely worn away locally before the next ice advance,
FIG. 506. — Diagram showing the intimate association of stratified and
unstratified drift.
so that stratified deposits connected with a second or later advance
may have been made on a driftless surface, and subsequently buried.
4. Intermorainic stratified drift may have originated at the outset
in all the ways in which supermorainic drift may originate. It be-
came intermorainic by being buried in some one of the various ways
in which stratified drift may become submorainic.
Topographic distribution of stratified drift. — Though stratified
drift is most abundant in valleys and lowlands, it is not confined to
these positions. Kames are measurably independent of valleys and
lowlands, and though eskers often show a tendency to follow valleys,
THE PLEISTOCENE OR GLACIAL PERIOD.
379
they often disregard topography to the extent of crossing ridges and
uplands a few hundred feet in height (200 to 400 feet in Maine *).
Kame-terraces and deltas, also, are often well above the bottoms of
the depressions with which they are associated.
FIG. 507. — Section of glacial drift which, though not stratified, was largely worked
over by water. The stones are water-worn rather than glacier-worn. North-
east part of Newark, N. J. (N. J. Geol. Surv.)
Changes in Drainage Effected by Glaciation.
The great and unequal erosion of the ice-sheets, and especially the
great and unequal deposition of the drift, produced a profound effect
upon the topography of the planer parts of the area affected by glacia-
tion. One of the conspicuous results of this alteration of the topogra-
phy was the derangement of the drainage. One of the results is seen
1 Stone, Mono. XXXIV, U. S. Geol. Surv., p. 434.
380
GEOLOGY.
in the thousands of lakes which affect the surface of the later drift,
and to a less extent, the surface of the older. The basins of these
lakes or ponds arose in various ways. There are (1) rock basins pro-
duced by glacial erosion; (2) basins produced by the obstruction of
river valleys by means of the drift; (3) depressions in the surface of
the drift itself; and (4) basins produced by a combination of two or
more of the foregoing. The third class, as above, may be subdivided
into depressions in the surface of (a) the terminal moraine, (6) the
ground moraine, and (c) stratified drift. Since the stratified drift in
FIG. 508. — Diagram illustrating normal drainage in the driftless area of
Wisconsin and Illinois.
which the lakes of this last sub-class lie is largely in valleys, it would
not be altogether inappropriate to class Borne of them with group (2) .
In addition to the lakes and ponds now in existence, there have
been others of a more temporary character. Some of them have
already become extinct by reason of filling or by the lowering of their
outlets since the ice melted; others depended for their existence on the
presence of the ice, which often obstructed valleys, giving rise to basins.1
The ice also developed basins outside of valleys, when the surface slope
was favorable.
*For examples of such lakes, see Glacial Geology of N. J., pp. 151-159, and Fair-
child, Bull. Geol. Soc. Am., Vol. X, pp. 27-68, and Stage XII following.
THE PLEISTOCENE OR GLACIAL PERIOD.
381
Another result is to be seen in the changes in the courses of the
streams. In many cases, pre-existing valleys were filled with drift,
so that when the ice melted the old channels were obstructed at many
points, and surface drainage was forced into courses which were partly
new. In other cases, the ice, by encroaching on the middle course
of the valley, as in the case of the Ohio, forced drainage around its front,
FIG. 509. — Diagram illustrating characteristic drainage in the glaciated area of
southeastern Wisconsin.
and the drainage lines thus established by force, were often held after
the ice melted.
There are few streams of great length in the area covered by the
ice, which were not turned from their old courses for greater or less
distances by the ice or the drift. The Mississippi, the Ohio, and the
Missouri, the master streams of the United States within the glaciated
area, and a host of their tributaries, as well as many streams tribu-
tary to the St. Lawrence, suffered in this way. The history of some
of these changes has been studied in detail,1 but the history of the
382 GEOLOGY.
changes is often difficult of reading. The outlines of drainage basins,
as well as the courses of individual streams, were often affected.
One of the characteristics of streams which have been thus de-
ranged is found in the lack of harmony between different parts of their
valleys. Within the glaciated area a stream often flows in a capacious
preglacial valley, then in a narrow post-glacial gorge of wholly different
aspect, whence it may emerge again into another section like the first.
Most streams whose courses were modified by the ice or its deposits
afford illustrations.
Again, preglacial valleys, even valleys of considerable length, were
sometimes filled completely, so that their courses are only known, so
far as they are known, by borings, which reveal the great depth of
the drift, and of the old channel. Many stream valleys, in the areas
of heavy drift, are wholly postglacial, showing the completeness with
which the old drainage lines were sometimes effaced.
The Succession of Ice Invasions.
It was formerly thought that there was but a single ice invasion
of brief duration, followed by a rapid retreat attended by great floods
arising from the melting of the ice; but the more careful studies of
later years have revealed a series of invasions separated by very
considerable intervals. It is not yet known how far the ice re-
treated in the intervals between the advances, but there is con-
vincing evidence that some of the intervals were long, much longer
than the period which has elapsed since the last ice retreated. There
is also good evidence that in some of them the climatic conditions
became at least as mild as they are today. While there are differ-
ences of view with reference to the entire disappearance of the ice-
sheet from the plains of Labrador and Keewatin, and respecting the
1 For changes in the Mississippi and in the rivers of Illinois, see Leverett, Mono.
XXXVIII, U. S. Geol. Surv., Chapter XII. For changes in the Upper Ohio, see
Chamberlin and Leverett, Am. Jour. Sci., Vol. XLVII, 1894 (contains references to
earlier work of Car 11, Chance, White, Stevenson, Lewis, Wright, Lesley, Spencer,
Randall, and Foshay, in the same region) . For changes in the Erie and Ohio Basin, see
Leverett, Monogr. XLI, U. S. Geol. Surv., Chap. Ill, and Tight, Professional Paper, No.
13, U. S. Geol. Surv., and for changes in the course of the upper Missouri and its tribu-
taries, see Todd, Science, Vol. XiX, p. 148 (1892), Geol. of S. Dak., pp. 128 and 130
(1899) , and Bull. 144, U. S. Geol. Surv. Changes in drainage in New York have been
summarized by Tarr, Phys. Geol. of New York, 1902, with references to earlier literature.
THE PLEISTOCENE OR GLACIAL PERIOD. 383
estimate to be put upon the importance of the interglacial intervals,
the above statements are fully justified by the data now accumulated.
Besides the greater advances and retreats, there were numerous halts
or oscillations which probably affected the oncomings as well as the
retreats of the ice.
The proofs of the interglacial intervals and the evidences of their
duration are found in the surface changes which were wrought by
drainage after the deposition of one sheet of drift, and before the depo-
sition of the next, in the depths to which earlier sheets of drift were
leached and oxidized by weathering before the deposition of later
ones upon them, in the accumulations of peat, soil, etc., now found
between different sheets of drift, and in some cases in the changes
of topographic attitude which intervened between the deployment
of successive ice-sheets.1
The following are the American stages of the glacial period now
recognized in the interior of North America, numbered in the order
of their age:
XIII. The Champlain sub-stage (marine).
XII. The glacio-lacustrine sub-stage.
XI. The Later Wisconsin, the sixth advance.
X. The fifth interval of deglaciation, as yet unnamed,
IX. The Earlier Wisconsin, the fifth invasion.
VIII. The Peorian, the fourth interglacial interval.
VII. The lowan, the fourth invasion.
VI. The Sangamon, the third interglacial interval.
V. The Illinoian, the third invasion.
IV. The Yarmouth, or Buchanan,2 the second interglacial interval.
III. The Kansan, or second invasion now recognized.
II. The Aftonian, the first known interglacial interval.
I. The sub- Aftonian, or Jerseyan, the earliest known invasion.
These stages were by no means equal, the earlier being markedly
longer than the later. There was something like a geometrical grada-
tion from the earliest and longest to the latest and shortest.
1 Distinct glacial epochs and the criteria for their recognition, Jour, of Geol., Vol. I,
pp. 61-84.
2 The Buchanan gravels lie between the Kansan and lowan drift-sheets, in locali-
ties where the Illinoian is not present, and hence it is not quite certain what inter-
val is represented by their deposition.
384 GEOLOGY.
I. The sub-Aftonian, or Jerseyan, glacial stage. — In Iowa there
is found a very old drift-sheet lying beneath the Kansan drift-sheet,
with sand and gravel, peat, old soil, and other products of an ancient
surface between them. It is not now known that this sub-Aftonian
drift-sheet comes to the surface, except as exposed by erosion, in Iowa
or other parts of the Keewatin area, and it is not yet certain wrhether
the oldest portions of the Labradorean drift are to be correlated with
it or not. It is reasonable enough in itself to believe that the earliest
ice invasion may not have pushed as far southward as a later one,
and such a view is held relative to the earliest glacial formation of
Europe.1 In Pennsylvania 2 and New Jersey,3 the frayed edge of
a very old sheet of drift emerges from beneath the much later drift
of the region, and this older drift may not improbably be the equiva-
lent of the sub-Aftonian of Iowa, but as direct connection cannot be
traced, the correlation is uncertain.4 The sub-Aftonian is a typical
sheet of till notable for the relatively high percentage of its green-
stone erratics. It is exposed by erosion, or artificially, near Afton,
at Oelwein, and at other points in Iowa, and probably embraces nearly
all the sections of " lower till " cited by McGee in his paper on the
drift of northeastern Iowa.5
II. The Aftonian interglacial stage. — Overlying this till sheet at
many points is a stratum of sand and gravel, and at some points beds
of peat and muck, with stumps and branches of trees, together with
the physical indications of an interval of erosion and weathering. It
is not wholly clear whether the assorted drift constituted the glacio-
fluvial products of the closing stage of the sub-Aftonian ice epoch,
or was derived by secondary action from the drift during the inter-
glacial interval. In the typical localities between Afton and Thayer,
Iowa, the deposit contains bowlders of till, showing that it is truly
secondary, but this does not define its precise age. In some districts
assorted drift is sufficiently prevalent and continuous at this horizon
to give rise to local systems of flowing wells. Near the typical locali-
'Geikie's Ice Age, 3d ed., and Jour. Geol., Vol. Ill, p. 241.
2 Williams, E., Proc. Am. Phil. Soc., Vol. XXXVII (1898), p. 84.
3 Salisbury, Annual Report of State Geol. of N. J., 1893.
4 The Albertan drift (province of Alberta, Can.), formerly thought to be the proba-
ble equivalent of the sub-Aftonian, is probably not of glacial origin. Calhoun, unpub-
lished data.
5 Eleventh Ann. Report U. S. Geol. Survey.
THE PLEISTOCENE OR GLACIAL PERIOD.
385
ties named, great masses of this assorted material were plowed up
by the succeeding Kansan ice-sheet and incorporated in its till, as shown
in Fig. 511. The organic remains in the interglacial beds seem to
imply a cool temperate climate, but as a cool temperate stage must
be passed through twice in every transition from a glacial climate
to a warm one and back again, organisms indicating a cool climate
FIG. 510. — Section of drift at Thayer, Union County, la. The stratified drift below,
making up the larger part of the section, is Aftonian. It is overlain by Kansan
till. (Calvin, Iowa Geol. Surv.)
do not necessarily show how great an amelioration may have been
reached, unless the record is known to be complete. The length of
the Aftonian interval has not been well determined, from lack of ade-
quate accessibility, but it was at least a notable interval. The pebbles
are much decayed and the soils, peat, etc., imply a considerable lapse
of time.
The old drift in western Pennsylvania doubtfully referred to the
sub-Aftonian stage is in somewhat like manner associated with impor-
386 GEOLOGY.
tant gravel deposits, and streams of valley gravels stretch far down
the drainage courses that then led away from the ice-edge. This is
notably true of the Allegheny and Ohio valleys. These old glacial
gravels are so related to the present trenches of these streams as to
seem to imply a channel erosion of 200 feet and more since their depo-
sition,1 though this interpretation has been questioned.
FIG. 511. — Section \ mile west of Thayer, showing masses of Aftonian gravel included
in the Kansan till. The most conspicuous mass is near the center of the figure.
The masses of gravel thus included are not cemented, and it is thought that they
must have been plowed up and included while in a frozen condition. The basal
part of the section at the right is Aftonian. (Calvin, la. Geol. Surv.)
The products of the glacial waters of this stage in eastern Penn-
sylvania and New Jersey were commingled with non-glacial wash-prod-
ucts and will be discussed under the non-glacial formations (Columbia,
p. 447).
The Natchez formation. — At Natchez, Mississippi, there is a section of assorted
material about 200 feet in thickness which is chiefly made up of derivatives from
1 Leverett, Mono. XLI, U. S. Geol. Survey, p. 235.
THE PLEISTOCENE OR GLACIAL PERIOD.
387
the Lafayette formation, upon which it rests unconformably (Fig. 513); but
it also contains crystalline pebbles and calcareous clays assignable to wash
from the glacial regions, all other assignments seeming to be excluded by a
special investigation. A marked interval between its deposition and that of
the overlying loess is indicated. As the sub-Aftonian and Aftonian deposits
are the only older ones with which great gravel deposits are known to be asso-
ciated, and as the Natchez deposit must be referred to an early Pleistocene stage
because the great Mississippi trench, 60 miles more or less in breadth, has been
FIG. 512. — Section just east of Oelwein, la. 1, Sub-Aftonian (Jerseyan); 2, Aftonian:
3, Kansan; and 4, lowan.
excavated since it was formed, reference to one of these two stages is more plausi-
ble than to any later one. This reference is strengthened by the fact that almost
the whole formation — which was clearly a valley train leading back to the drift
area — has been removed.
Assuming the correctness of this reference and combining it with other data,
the following tentative conception of the sub-Aftonian and Aftonian stages is
reached. The ice-sheet spread from the Keewatin and Labradorean centers to
the approximate limit of the known drift in the Mississippi valley, and deposited
a typical sheet of bowlder clay (sub-Aftonian) and also gave rise to great valley
trains of glacio -fluvial material that stretched from the drift border to the Gulf,
filling the low-gradient valleys of the time to depths of 30 to 50 feet near the
drift border, and of 200 feet near the Gulf (Natchez formation). The invasion
388
GEOLOGY.
of the ice blocked up many northward trending valleys and caused their streams
to find new courses along the ice border. The present Ohio and Allegheny rivers
seem to have been formed by the union of several streams that previously flowed
into the Erie basin. The Missouri river seems to have' been formed by a similar
combination of many streams that previously flowed northerly and easterly
but some part of this readjustment of the drainage seems to have been later
FIG. 513. — The unconformity between the Natchez above and the Lafayette below.
The line of contact is indicated by the dotted line.
than this stage. Including these later changes, the Ohio and Missouri rivers
may be pictured as two great drainage arms embracing the border of the ancient
ice-sheet and carrying away its waters. Rather low gradients and a low ele-
vation in the lower Mississippi seem thus to be indicated.
III. The Kansan glacial stage. — As defined by Calvin, Bain, and
others who have specially studied it,1 the Kansan stage is represented
by a typical sheet of till occupying a large surface area in Kansas,
Missouri, Iowa, and Nebraska (Fig. 470), and theoretically extending
1 Reports of the Iowa Geol. Survey.
THE PLEISTOCENE OR GLACIAL PERIOD. 389
under the later glacial formations to the northward as far back as the
Keewatin center of radiation. Much of this sheet of drift, as originally
developed, has probably been rubbed away by later glaciations. Pre-
sumably a similar sheet was formed by a contemporaneous ice move-
ment from the Labradorean center, but this has not been certainly
identified in the region east of the Mississippi. It probably fell short
of the later advances there, and lies concealed beneath their debris,
so far as it has escaped destruction. The Kansan formation is a pro-
nouncedly clayey till, with exceptionally little assorted drift. Glacial
water action seems to have been notably inefficient. Observation
on this and the succeeding glacial formations has forced the aban-
donment of the earlier conception of vast floods as the inevitable
accompaniment of the ice-melting, the meagerness of marginal drain-
age in some cases being one of the strangest of all the strange
phenomena of the glacial period. No great deposits of sand and gravel
have been found in, or on, or leading away from the edge of this
formation.
Originally the surface of the Kansan till sheet seems to have been
rather plane, but it has since been markedly eroded, and bears clear
evidence of great age as compared with the latest drift. As the next
younger sheet (Illinoian sheet) of drift overlaps its east border near
the Mississippi (Fig. 514), comparison along the junction shows that a
large part of the erosion of the Kansan drift took place before the
superposition of the Illinoian drift. A long intervening epoch is there-
fore inferred, an inference strengthened by the deep weathering of the
Kansan drift, and the pronounced decay of its bowlders.
IV. The Yarmouth interglacial stage.1 — The erosion just mentioned
is perhaps the best evidence of a prolonged interval between the Kansan
and Illinoian ice invasions; but in the tract where the Illinoian till
sheet overlaps the Kansan, in eastern Iowa, an old soil with deep sub-
soil weathering is found to have developed on the surface of the latter
before its burial. Some vegetable accumulations have also been pre-
served, a good instance being found near Yarmouth, Iowa, whence the
name was taken. Bones of the rabbit and skunk have been identified
from this horizon. A climate not essentially different from the present
is inferred.
1 Leverett, Mono. XXXVIII, U. S. Geol. Survey.
390
GEOLOGY.
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THE PLEISTOCENE OR GLACIAL PERIOD. 391
V. The Illinoian glacial stage. — The typical formation of this stage
was a sheet of till occupying the surface in the southern and western
portions of Illinois (Fig. 514), and running back under the later forma-
tions to the northeast toward the Labradorean center of radiation.
Its surface exposure is traceable northerly into Wisconsin and easterly
into Indiana and Ohio, but it is not identified with any confidence
farther east, where the margin seems to have fallen back, and to have
been overridden by the ice of the Wisconsin epoch. The identifica-
tion of the Illinoian drift in the Keewatin area is yet an open question.
Like the Kansan drift, the Illinoian is made up of clayey till, without
marked association with assorted drift in most regions. There is
appreciably more assortment of the material, however, than in the
Kansan drift. There are tracts of kames in some sections, notably a
belt running southwest from Tower Hill, Illinois, to the margin of the
drift. The original surface was generally plane, and only a limited
tendency to ridging in the fashion of terminal moraines has been found.
The west edge of the Illinoian ice-lobe crossed the present course of the
Mississippi between Rock Island and Fort Madison, and pushed out into
Iowa a score of miles, forcing the river in front of it.1 Previously, the
Kansan lobe had invaded the border of Illinois, and probably forced
the Mississippi east of its present course, if indeed it did not already
have a course east of its present one before the Kansan ice appeared.
Efforts to trace out the early courses of the Mississippi under the thick
mantle of drift in Illinois have not been entirely successful.
VI. The Sangamon interglacial stage.2 — Like the preceding Later-
glacial stages, this is characterized by peat, muck, old soil and sub-
soil, weathering, surface erosion, etc. Judged by these, the interval
was not as long as the Yarmouth.
VII. The lowan glacial stage.3 — The lowan ice invasion is recorded
in a thin sheet of till (Fig. 512), marked by an exceptional profusion
of large granitoid bowlders which lie chiefly on the surface and are
somewhat aggregated into a bowlder belt on the eastern border of
the tract. The typical lowan drift was formed by a lobe of the Kee-
watin ice-sheet, occupying the north-central part of Iowa (see map,
Fig. 514). It fell much short of the Kansan invasion of the same
1 Leverett, Mono. XXXVIII, U. S. Geol. Survey.
2 Idem.
3 See Calvin, Bain, and others. Reports Iowa Geol. Surv.
392 GEOLOGY.
region. A drift sheet in northern Illinois, apparently much younger
than the recognized Illinoian, has been tentatively regarded as the
Labradorean equivalent of the typical lowan, but this view is not
held very firmly. As with the Kansan and Illinoian, the tendency to
morainic ridging was very feeble. The outwash from the border was
also scant, unless the loess silt represents it, in which case the drainage
must have been extremely gentle. While the loess is not confined to
this stage, and probably not to the glacial regions even, the chief loess
formation of the immediate Missouri and Mississippi basins seems to be
approximately of lowan age. The loess will be considered later. Fig.
514 shows the relations of the several drift sheets in Iowa and Illinois.
VIII. The Peorian interglacial stage.1 — This is characterized in the
same way as the preceding interglacial intervals, but less strongly, and
obviously represents a less important epoch. The interglacial fossil-
iferous beds near Toronto, referred to later, have been assigned to this
stage, but they may, perhaps, be older.
IX. The Earlier Wisconsin glacial stage. — The formations of the two
Wisconsin stages together occupy much larger surface areas than the
preceding, because they were not overlapped by later drifts, and they
are hence less modified. Besides this, they seem to have had stronger
features originally. The till-sheets are marked not only at their borders,
but at intervals in the oscillatory recession of the ice, by declared
terminal moraines. Kames, eskers, drumlins, and other special forms
of aggregation and of outwash mark the surface, and reveal the mode
of action of the ice and the glacial waters in a conspicuous way, and
are in contrast with the nearly expressionless surfaces of the older
sheets of drift. A part of this difference is due to the greater freshness
of the Wisconsin formations; but the larger part, apparently, is as-
signable to a stronger original expression. This is more markedly
true of the later Wisconsin drift than of the earlier. At least three
successive terminal morainic tracts characterize that portion of the
Early Wisconsin formation in Illinois which was not covered by the
Late Wisconsin. The outermost of these lies on the border of the Wis-
consin drift, and marks the outermost limit of the ice; the others lie
within this outermost belt, and are rudely concentric with it, marking
stages of halt, or of minor advance in the general oscillating retreat of
the ice.
1 Leverett, op. cit.
THE PLEISTOCENE OR GLACIAL PERIOD. 393
X. The fifth interval of recession. — There was an interruption of
the retreat of the earlier Wisconsin ice at some unknown line within
the area of the later drift, followed by a re-formation of the ice-lobes,
and a re-advance of the ice-front. It does not appear that this interval
was very long, but it was sufficient to permit the lobes of the ice-sheet
to change their relative sizes and their relations to one another to
such an extent that the moraines of the later stage at some points
cross those of the earlier at large angles. It is uncertain whether
the interval should be put in the preceding class, as the shortest
representative of a declining series, or referred to a different category,
and it has been left unnamed.
XI. The Later Wisconsin glacial stage. — Following this epoch of
re-adjustment, the ice margin assumed a pronounced lobate form, and
gave rise to the most declared moraines, drumlins, and other distinc-
tive glacial formations of the period. The ice radiated not only from
the Labradorean, Keewatin, and Cordilleran centers (Fig. 469), but
from many isolated heights. Nearly all the well-known mountain
glaciation of the west is referred to this epoch. The drift-sheet of
this stage is characterized by enormous terminal moraines, by great
bowlder belts, by unusual developments of kames, eskers, drumlins,
outwash aprons, valley trains, and other diagnostic features of glacial
action and glacio-fluvial cooperation. This drift-sheet, far beyond
all the others, bears the stamp of the great agency of the period. The
disposal of the ice in great lobes is referable to the influence of the
great basins. Field studies indicate that broad, smooth-bottomed
basins, elongate in the general direction of the ice movement, favored
the prolongation of the ice into broad lobes, while sharp, deep valleys
of tortuous course or transverse attitude had little effect upon the
extension of the ice. A study of the accompanying map (Fig. 470)
will make clear the relation between the great ice-lobes and the broad,
smooth valleys lying under or back of them.
The Later Wisconsin drift is characterized in some places1 by
nearly a score of concentric moraines which, in some cases, represent
re-advances of the ice in the course of its general retreat, and in others
perhaps nothing more than halts sufficient to permit an exceptional
accumulation of drift at the ice border. There appears to have been
1 Minnesota, Upham, 9th Ann. Kept. Geol. and Nat. Hist. Surv. of Minn., 880; Lev-
erett, Mon. XLI, U. S. Geol. Surv. 5,,
394 GEOLOGY.
exceptional vigor of ice action, correlated with rapidity of melting,
resulting in a sharp contest between the antagonistic agencies that
made for advance and retreat. The older drift-sheets, so far as over-
ridden by the ice of this epoch, were cut away more largely than in
preceding epochs, and the scoring of the rocks below was more preva-
lent and profound. This was notably so in the great thoroughfares of
movement, and for obvious reasons less so where the lateral borders
of the lobes only lapped upon the older drift. Extensive overriding
of the older drift, without complete removal, occurred in some dis-
tricts, notably in Illinois and Michigan, as determined by Leverett.
All of these several sheets of drift have never been seen in super-
position and the history sketched is based on the relations of the sheets
of drift at different points.1 Theoretically, and perhaps really, the
FIG. 515. — Diagram illustrating the imbrication of the successive sheets of drift. The
full lines represent the portion of the drift-sheets not overspread, or but little over-
spread, by later ice-sheets; the broken lines represent the portions of the successive
drift-sheets which were covered by ice at a later time. 1 corresponds to Jerseyan
or sub-Aftonian, which in general is less extensive than the Kansan, though locally,
as in New Jersey, it extended farther south than any other. 2 represents the
Kansan drift, the southern margin of which is not covered by younger drift. 3, 4,
and 5, respectively, represent the Illinoian, lowan, and Wisconsin sheets of drift.
several sheets of drift are imbricated as shown in Fig. 515; but each
sheet of drift is discontinuous beneath the overlying one, and this
discontinuity goes so far that beneath the Wisconsin drift, for example,
the several sheets are more commonly wanting than present. Fig. 515
gives diagrammatic expression to the conception here presented.
XII. The glacio-lacustrine sub-stage. — In the course of the retreat
of the ice of the later Wisconsin epoch, a complex series of pondings of
water between the ice-border and the higher land fronting it took
place, particularly in the St. Lawrence basin, giving rise to a succession
of temporary, constantly changing lakes, with shifting outlets. This
was but an episode of the Later Wisconsin glacial stage, but it con-
stituted a special phase of action, and merits recognition because of
its individuality.
1 Jour, of Geol., Vol. I, pp. 61-84. An exposition of the criteria for the recognition
of distinct glacial epochs.
THE PLEISTOCENE OR GLACIAL PERIOD. 395
As the ice border withdrew to the north of the divide separating
the St. Lawrence basin from the Mississippi basin, the glacial waters
were ponded between the ice on the north and the divide on the south.
To find escape across the divide, the waters were compelled to rise
to the heights of the lowest available cols. At first, nearly every
considerable depression in the divide to the south was occupied by a
discharging stream, and the ponded water to the north formed innumer-
able small lakes.1 But as the ice retreated farther into the basin,
the sizes of the lakes tended to increase as their basins were enlarged;
but at the same time the ponded waters tended to unite along the
edge of the withdrawing ice, and to utilize only the lower passes across
the divide to the south. This tended to lower the lakes, and hence
to reduce them. There thus followed a complex series of antithetical
changes resulting in the making and unmaking of lakes. This con-
tinued until the obstructing ice withdrew from the axis of the St. Law-
rence basin. The last of the shifting series of ice-ponded lakes of this
basin then disappeared, leaving the present rock-bound lakes as their
successors. The full details are too voluminous for introduction here,
but a brief sketch of the history of the leading lakes will indicate the
nature of the changes which took place.
When the end of the Lake Michigan ice-lobe withdrew a little within
the Lake Michigan basin, a crescentic belt of water formed about its
southern extremity, and found a point of discharge into the Illinois
valley through a col southwest of Chicago, which it proceeded to
erode to greater depths. This valley has since become the site of
the Chicago drainage canal.2 A glacial lake (the extinct Lake Chicago)
was thus initiated, and as the ice-lobe withdrew, the lake gradually
extended northward (Fig. 516).
A similar lake was formed about the head of the Lake Superior
ice-lobe, and discharged through an outlet at the head-waters of the
Brule and St. Croix Rivers to the Mississippi. Another lake of like
origin (Lake Maumee) was formed about the end of the Erie ice-lobe,
and discharged its waters by way of Fort Wayne into the Wabash,
and thence to the Gulf.
1 For local lakes in New York, see Fairchild, Bull. Geol. Soc. Am., Vol. X, pp. 27-68.
2 This valley appears to have served a similar function in earlier stages of glacial
retreat, but it was not the preglacial outlet of the Lake Michigan basin, as there are
much lower channels (now buried) both north and east of it.
396
GEOLOGY.
As the ice-lobe that lay in the Erie basin retreated, the crescentic
Lake Maumee at its end expanded, one horn extending eastward on
the southern border of the lobe, and the other northward on the north-
western border, until the latter found a pass along the south side of
FIG. 516. — The beginnings of the Great Lakes. The ice still occupied the larger
parts of the present lake basins. (After Taylor and Leverett, U. S. Geol. Surv.)
the Saginaw ice-lobe, lower than the Fort Wayne outlet. This pass was
the Imlay outlet. The escaping waters then skirted the edge of the
Saginaw ice-lobe to the valley of the Grand river, following which
they crossed the lower peninsula of Michigan, and joined Lake Chicago
(Fig. 517), the left horn of which had, by this time, reached thus far
north. This constituted the second stage of Lake Maumee.
THE PLEISTOCENE OR GLACIAL PERIOD
397
Somewhat later, the Saginaw ice-lobe retired so that a crescentic
lake (Lake Saginaw) gathered about its extremity, and discharged
through the Grand River outlet into Lake Chicago, and thence by
the Illinois route to the Mississippi. For a time, Lake Maumee con-
tinued to discharge by the Imlay outlet into Lake Saginaw, and thence
to the Mississippi; but in the course of the retreat, a lower outlet across
FIG. 517. — A later stage in the development of Lakes Chicago and Maumee. The ice
has retreated farther, and the outlet of Lake Maumee has been shifted. (Leverett
and Taylor, U. S. Geol. Surv.)
the " thumb " of eastern Michigan was discovered, and the Imlay
outlet was abandoned.
Later, the whole Erie basin, and a portion of that of Ontario, became
free from ice, and a lake twice the area of the present Lake Erie developed
(Lake Arkona), and was marked by its own set of beaches. According
to the recent determinations of Taylor, an advance of the ice followed,
closing the lower outlet across the Thumb of Michigan, and forcing
the water to occupy a higher one at Ubly. This stage was attended
by the formation of a beach (the Belmore) at a higher level than the
Arkona beaches, which were submerged but not wholly obliterated.
398
GEOLOGY.
THE PLEISTOCENE OR GLACIAL PERIOD. 399
The water-body at this stage is known as Lake Whittlesey (Fig.
518).
At a still later stage, the Saginaw ice-lobe had retired into the
Huron basin, and the ponded waters in the Saginaw basin became
confluent with those in the Erie basin, which had, in the meantime,
become extended into the borders of the Ontario basin, but were blocked
in that direction by the Ontario ice-lobe. The extensive water body
thus developed is known as Lake Warren (Fig. 519). At first, this
lake discharged through the Grand River outlet into Lake Chicago; but
later the eastern end appears to have worked its way along the south
border of the Ontario ice-lobe into the Finger Lake region of New
York, and to have reached at length the Mohawk valley, through
which it discharged into the Hudson, thus transferring the sea-con-
nection of the Erie basin from the Mexican Gulf to the Atlantic Ocean.
In the course of time, the shape of the water body centering about
the Ontario basin was changed as the ice retreated, and the Mohawk
outlet was lowered at the same time. Three successive stages of this
kind have been named Lake Dana, Lake Lundy, and Lake Iroquois
(Fig. 520), respectively, all discharging through the Mohawk.
Meantime, the glacial lakes in the basins of Lake Michigan and
Superior experienced analogous shiftings of areas and of outlets. While
Lake Iroquois was discharging through the Mohawk valley, Lake
Algonquin (Fig. 521), formed by the coalescence of the glacial lakes
of the Superior, Michigan, and Huron basins, was discharging its waters
eastward. At first the outlet was probably by the St. Glair-Erie route,
through Lake Iroquois, to the Mohawk; but later, when the ice had
retired farther north, an outlet appears to have been effected from
Georgian bay, via the Trent river to Lake Iroquois (Fig. 521). This
lower outlet to the north was probably due to a depressed condition
of the area to the northeast, due to the weight of the ice mass and
the attraction of the latter on the water adjacent to it.
When at length the Ontario ice withdrew from the Adirondacks
so far as to permit the ponded waters to find an outlet lower than that
by way of the Mohawk, between the ice and the north base of the
mountains, a new series of lowerings of the ponded water-body followed.
At first the outlet seems to have skirted the Adirondacks and emptied
into a glacially ponded water-body (glacial Lake Champlain) that occu-
pied the Champlain basin, and discharged southward into the Hudson.
400
GEOLOGY.
03 >
f|
111
.
113
300
5 la
II*
THE PLEISTOCENE OR GLACIAL PERIOD.
401
FIG. 520. — Lake Erie and Lake Iroquois; a stage in the history of the eastern Great
Lakes, after the ice had retreated so as to open the Mohawk outlet. (Gilbert,
U. S. Geol. Surv.)
FIG. 521. — The Great Lakes at the Algonquin-Iroquois stage. (After Taylor.)
402 GLOLOGY.
With further stages of ice retreat, the outlet was let down to the Cham-
plain arm of the sea presently to be noted. By this time Lake Algon-
quin had given place to the great Nipissing Lakes (Fig. 522), which
had their outlet via Lake Nipissing to the Ottawa, and thence to the
Champlain arm of the sea. Subsequently the outlet was shifted to
its present position, probably by gentle warpings of the surface.1
Without doubt similar complicated lake histories attended the
retreat of the ice in the Mackenzie and Hudson Bay basins, but little
is yet known regarding them.
A very important lake was also formed in the Red River valley
of the north (Lake Agassiz), discharging in its earlier history, into the
Minnesota river at Lake Traverse. As Lake Agassiz was not con-
nected with the complex system of basins of the St. Lawrence valley,
it had a comparatively simple history. It grew to the northward with
the retreat of the ice which held it in at that end, and continued to dis-
charge into the Minnesota river at Lake Traverse, cutting down its
outlet and forming a series of beaches about its borders, until the retreat
of the ice enabled it to find a northerly outlet in some position yet un-
known. While discharging by this northerly outlet, it made another
set of beaches. On the further withdrawal of the ice, its waters were
discharged, and the lake became extinct. Lakes Winnipeg and Winni-
pegosis may be regarded as its diminutive successors in a sense, but
they are rock-bound or earth-bound lakes, while Lake Agassiz was
ice bound on its northerly border.2 Multitudes of smaller lakes came
into existence in the regions of strong relief as the ice withdrew. Their
histories are for the most part less complicated. Few of them have
been studied in detail.
It is probable that there were corresponding lacustrine sub- stages
at the close of each of the several glacial epochs, but their history has
not been worked out, and because of the overriding of later ice, will
probably never be deciphered in detail.
The evidence which demonstrates the existence of these expanded
lakes is found chiefly in the deposits which they made, and in the
topographic features which they developed about their shores. Many
of the former shore-lines have been traced in detail, and most of them
1 An account of the history of the Great Lakes, by F. B. Taylor, is found in
Studies in Indiana Geography.
2 The glacial Lake Agassiz, Upham, Mono. XXV, U. S. Geol. Survey, 1895.
THE PLEISTOCENE OR GLACIAL PERIOD. 403
depart notably from horizontality. Those of different stages of the
lakes frequently depart unequally from a common plane. In general,
they rise to the north and northeast.
XIII. The Champlain sub-stage. — The significant feature of this
stage is represented in Fig. 522, which represents an arm of the sea
extending up the St. Lawrence to Lake Ontario, filling the basin of
Lake Champlain, and probably connecting southward by a narrow
strait along the site of the Hudson valley with the ocean.1 The sedi-
ments deposited in this arm of the sea contain shells and bones of marine
animals. The marine fossils are found at various places about Lake
Champlain at altitudes varying from 400 feet or less about the south
end of the lake, to 500 feet at the north end, and about 600 feet near
the east end of Lake Ontario.2
The most distinctive deposit made in this Champlain arm of the
sea is laminated clay, the material for which was partially supplied
by drainage from the ice jto the liorth. While the " Champlain clays"
are the best-known phase of the deposits of this stage, sand and gravel
were deposited contemporaneously in appropriate situations. The
clays of the Hudson valley are extensively used for brick. Similar clays
occur in the Connecticut and some other New England valleys, and
in the valley west of the Palisade ridge. In all cases, the clays rise
notably to the northward and serve as a rough measure of the post-
glacial change of altitude of the land.3
At about the same time the sea stood higher than now relative to
the land on the coast of Maine, where marine shells, including species
of My a, Astarte, Leda, and Yoldia, among many others, occur up to
elevations of 200 feet or more.4 Marine fossils of post-glacial age occur
up to elevations of about 600 feet above James Bay,5 and other marks
1 Feet, Jour, of Geol., Vol. XII (1904), pp. 415-469, 617-661; Salisbury, Glacial
Geol. of N. J., pp. 196-200.
2Dawson, G. M. Am. Jour. Sci., 3d ser., Vol. VIII (1874), p. 143; Dawson, J. W
The Canadian Ice Age, p. 201, and Am Jour. Sci., Vol. CXXV, 1883.
3 Other papers touching the Champlain are the following: Reis and Merrill, 10th Ann
Kept. N. Y. State Geologist, 1890; Reis, Bull. N. Y. State Mus., Vol. Ill, 1895; Bald-
win, Ann. Geol., Vol. XIII, 1894; Davis, Proc. Bos. Soc. Nat. Hist., Vol. XXV, 1891;
Upham, Bull. Geol. Soc. Am., Vol. Ill, 1891; Kellogg, Science, Vol. XIX, 1892; and
Woodworth, Bull. 84 N. Y. State Mus.
4 Dana, Manual of Geology, 4th ed., p. 982; and Stone, Jour, of Geol., Vol. I,
pp. 246-254.
5 Bell. Am. Jour. Sci., 4th ser., Vol. I, pp. 219-228, 1896.
401
GEOLOGY.
THE PLEISTOCENE OR GLACIAL PERIOD. 405
of post-glacial submergence are reported at still greater heights in
Labrador.
The Loess.
The term loess is used with not a little latitude, both as a text-
ural and a formational name. Lithologically, loess is a variety of
silt intermediate between the finest sand and clay. In general, it is
free from stones of all sorts, except the concretions which have been
developed in it since its deposition. In the exceptional cases where
stones occur in it, they are confined to its extreme basal portion. At
its base, too, it is sometimes interstratified with sand, especially where
it is thick.
The composition1 of the loess is significant in that it contains
angular, undecomposed particles of the commoner carbonates, calcite
and dolomite, and silicates, such as the feldspars, the amphiboles,
the micas, etc. Even the rarer silicates, such as epidote, apatite,
tourmaline, zircon, etc., have been identified. Magnetite also is a
common, though never an abundant, constituent. These constituents
strongly suggest that the material of the loess was derived from the
flour of the glacial mill. In color it is predominantly buffish brown,
but in not a few places it has a bluish cast a few feet below the surface.
By virtue of its peculiar mode of adhesion and of its porosity, the
loess often stands with vertical faces (Fig. 523) for long periods, where
sand or clay would be degraded into slopes. Roads on the loess tend
to assume the form of miniature box canyons, because the loess of
the road-bed is washed or blown away, while that on either side stands
up with steep or even vertical slopes. Its porosity seems to be due
in part to the size, shape, and arrangement of its grains, and in part
to vertical tubelets that usually affect it, and which are supposed
to have been caused by rootlets. Weathered faces of the loess often
show a rude columnar structure (Fig. 524), the columns being one
to several feet in diameter. The loess often shows no stratification,
but in its coarser phases there is often some suggestion of such structure,
and when the loess proper is interbedded with sand, this suggestion
becomes distinct.
The best known portions of the loess in America and Europe are
associated with glacial formations, though the loess extends far beyond
1 Sixth Ann. Kept. U. S. Geol. Surv., pp. 244 et seq.
406
GEOLOGY.
FIG. 523. — A section of loess in Iowa, showing its ability to stand with vertical or
even overhanging faces. (Calvin.)
FIG. 524. — A section of the loess at Kansas City, showing its rude columnar structure,
(Mo. Geol. Surv.)
THE PLEISTOCENE OR GLACIAL PERIOD 407
the borders of the drift in some directions, in both continents, and in
America it occurs in the driftless area (Fig. 470). In Turkestan, Mon-
golia, and China,1 where loess has its greatest known development, it
is not known to be immediately associated with glacial formations,
though its age is probably about the same as that of the chief deposits
in Europe and America.
In North America, the loess does not occur east of the Mississippi
basin, and has no great development east of the Wabash river. The
greatest development is in Illinois, Iowa, Nebraska, and the States
lying south of them, even beyond the reach of the most extensive ice-
sheet. Within this area, its distribution is peculiar in that (1) it is
thick about the border of the area occupied by the lowan ice-sheet;
(2) it thins out on the inter-stream areas as it is traced away from
this border tract; while (3) it retains its thickness along the valleys,
especially the larger ones, but thins gradually from them. Especially
does it follow the main streams that lead away from the lowan drift-
sheet. It follows the Mississippi nearly to the Gulf, and is especially
thick along this stream and the Missouri. Its habit is to occupy the
bluffs immediately overlooking the valleys, and it was formerly known
as the Bluff formation on this account. In this position, it has
more than its average thickness and coarseness of grain, and grows
thinner and finer in grain back from the river bluffs until it is lost in
a vanishing edge, while its material, at the same time, loses its dis-
tinctive characteristics.
In the regions next south of the borders of the lowan and Wis-
consin drift-sheets, it mantles the divides between the main streams,
but farther south it is more confined to the valley borders. Within
the general area of its occurrence it has little regard for topography.
It can indeed hardly be said to have an upper limit. This indepen-
dence of topography is one of its significant features. Within the
drift-covered part of the Mississippi basin, the loess occurs (1) as a
mantle overlying the drift (Fig. 525), and (2) between sheets of drift.
Its relations to the drift-sheets make it clear that it was accumu-
lated at several different stages of the glacial period, but within the
glaciated area the accumulation at one of these stages far exceeds
1 Von Richthofen, China. This author early (1877) advocated the eolian origin
of the loess of China, but this explanation has not passed unchallenged. See Skertchley
and Kingsmill, Q. J. G. S., Vol.LI, 1895, pp. 238-254.
408
GEOLOGY.
that at all others, both in volume and areal extent. The loess deposited
at this stage is often referred to as " the loess/' and is usually cor-
related in time with the lowan drift, though the strict accuracy of this
correlation has been questioned. It is at least later than the Kansan
and Illinoian sheets of drift which it mantles, and earlier than the
Early Wisconsin which overlies it. Locally, a thin mantle of loess
oveilies the older part of the Early Wisconsin drift, and, more rarely
FIG. 525 — Loess overlying Kansan drift, with a thin band of pebbles at the junction;
Iowa. (Calvin.)
the younger. It even overlies the Late Wisconsin drift in places,
though the Wisconsin drift-sheets are usually free from it.1 Loess
does not appear in quantity between the Illinoian and Kansan for-
mations, nor between the Kansan and sub-Aftonian.
Outside the drift there are often two distinct sheets of loess. They
are sometimes separated by a well developed soil zone, beneath which
the surface of the lower loess shows the effects of prolonged weathering
and oxidation.2
of Geol., Vol. IV, pp. 929-937.
2 Report on Crowley's Ridge, Ark. Geol. Sur., pp. 224-235.
THE PLEISTOCENE OR GLACIAL PERIOD. 409
On portions of the Great Plains, and in some of the basins of the
Western mountain regions, there are deposits called loess, some of
which are closely similar to the loess of the drift region, while others
are quite different. But there is nowhere a development at all com-
parable to that on the borders of the plateaus of Asia, particularly in
China. In Washington and Oregon, material which in its general
character is quite similar to the loess of the Mississippi basin is
widespread.1
The loess of the Mississippi basin rarely attains a thickness of more
than a score or two of feet, and this only along main streams; but
exceptionally its thickness approaches 100 feet. Thicknesses of 10
feet are much more common than greater ones.
The loess contains characteristic accessories of two classes, namely,
concretions and fossils. The concretions are of lime carbonate and
iron oxide. The former are often irregular and of such shapes as to
have received the appellation of " petrified potatoes. " Concretions
of the sort to which this name is applied are usually though not always
hollow. The concretions of lime carbonate are often of other shapes,
for example, cylindrical. The ferruginous concretions take various
forms, one of which is the " pipe stem/' perhaps formed about rootlets.
The fossils of the loess are chiefly gastropods (Fig. 526). They were
originally reported to include both terrestrial and aquatic forms, and
this has much influenced opinion with reference to the origin of the for-
mation. According to Shimek, however, the shells in the upland
loess are almost exclusively those of land species, or such as frequent
isolated ponds.2 He finds a practical absence of those that frequent
rivers and lakes. There is, however, a lowland silt formation, classed
by some as loess, called by others loess-loam, in which fresh-water
fossils are found. The other fossils are bones and teeth of land mam-
mals.
Origin. — The origin of the loess has long been a standing puzzle,
and opinion is still divided between an aqueous and an eolian origin,
with a growing tendency toward the latter. Some geologists divide
the honors between the two hypotheses. There is little doubt that
the loess-like silt deposits which occur in the terraces of rivers are
1 Jour, of Geol., Vol. IX, p. 730.
2 Ibid., Vol. IV, pp. 929-937, and Loess Papers, Bull. Labr. Nat. Hist, Univ.
Iowa, 1904.
410
GEOLOGY.
of fluvial origin; but some investigators, while assenting to this con-
clusion, would exclude such deposits from the loess proper. Some,
indeed, would so define the loess as to make it an eolian product. The
distribution of the loess along the rivers naturally suggests a genetic
MO
n o p q
FIG. 526. — Loess Shells, a-b, Zonitoides minusculus (Binney); c-rf, Euconulus fulrus
(Drap.); -/• Strobilops labyrinthica (Say); g, Polygyra clausa (Say); h, P. tnui-
tilineata (Say); i-j, Succinea obliqua Say; k, S. avara Say; l-m, Polygyra
monodon (Rack); n, Bifidaria pentodon (Say); o, B. corticaria (Say); p, B. mus-
corwn (Linn.); q, B. armifera (Say). The small figures adjacent to some of the
large ones show the natural size of the shells.
relation to them. This is conceded, without proving that the loess
is fluvial.
By the aqueous hypothesis, the loess is assigned to direct deposi-
tion by the rivers, or their lake-like expansions. To make this possible,
it is necessary to suppose that the waters stood at elevations 200 to
600 feet higher than now, relative to adjacent surfaces. This involves
difficulties that have never been satisfactorily met, for great areas
Till:' I'Ll'lSTOCENE OR GLACIAL PERIOD. 411
which should have Invn covered by water according lo this hy-
pothesis, have no loess. Thus the loess occupies the bluffs on the
east side of the Mississippi river, down to the highlands of the south-
western part of Mississippi, where it mantles sin-faces which lie IUH)
or 100 feet above the present river, and overlook the lowlands of Louisi-
ana, where then1 is no loess. Between the bluffs ami the lowlands,
there is no restraining barrier, and no shore-line, or other topographic
features that should have been left by an estuary, had the depositing
waters assumed that form. Furthermore, if the waters of rivers or
their lake-- like expansions were high enough to cover the areas over-
spread by loess, it is not clear that there could have been an appro-
priate habitat for the abundant land fauna of the time.
I'nder the eolian hypothesis, or at least one phase of it, the river
flat> are supposed to have supplied the material of the loess, which
was whipped up by the winds and re-deposited on the adjacent up-
lands, perhaps being held, after deposition, by vegetation. The rivers
are thus made essential factors in the distribution, though not the
direct agents of deposition. The preponderance of loess on the east
sides of some main rivers is attributed to the prevailing westerly winds.
This hypothesis seems on the whole to best fit the phenomena of at
leasi a large part of the loess of the Mississippi basin. The constituents
of the loess, which appear to have come from the glacial grinding, were
derived either directly from the deposits made by glacial waters, or
from the secondary erosion of the glacial formations. It is probable,
too, that the derivation of loess silt from glacial drift directly, before
it became clothed with vegetation, and without the intervention of
rivers, should be recognized.1
v — Loess is described in the geological reports of the following
States: tew*, Vols. m, IV, V, Vll, VIII, IX, X, XI, XII, XIII, and XIV (Calvin,
Ixiin, Shimck, and others'); Illinois, Vols. V and VI (Shaw and Worthen); Missouri,
Kcports of 1855-71, 1872, and 1873-4, and Vols. IX and XII (Pumpelly, Broadheud,
Marl>ut. Todd. \Vinslo\v); Arkansas, Report on Orowley's Ridge; Kentucky, Report
on Jackson Purchase Region ( Loughridge) ; Tennessee, Geology of Tennessee, and
Resources of Tennessee (SatTonH; Louisiana, Reports of 1899 and 1902 (Harris
and YeateM; Mississippi. KVporfs of ix.yl and 1860 (Hilgard); Minnesota, Vol.
1. a. .,1 Import for isso, ^Vim-hell, IphanO; South Dakota, Hull. I (Todd), and
Nebraska. Vol. I (Harbour). Other references nre, Pumpelly, Am. Jour. Sci., Vol.
XV11, 1ST!); Mcllee and Call. idem.. Yol XXIY. ISS'J; Me(Jee, Kleventh Ann. Kept.
U. S. Geol. Surv.; Ohnmberlin and Salisbury, Sixth Ann. Kept. U. S. Geol. Sun-.;
Russell, Geol. Mag., Vol. VI, 1889; Todd, Am. Assoc. Adv. Sci., Vol. XXVII, 1987,
412 GEOLOGY.
The fact that the chief loess formation of the drift region is related,
in the way above described, to the area of the lowan drift, has led
to the conception that at the time of the lowan ice invasion, the glacial
streams were more sluggish and widely wandering than in most other
stages, and that by fluctuations between flood and recession, and by
shif tings, they exposed more extensive silty flats, while at the same
time the climate was more arid, the silt flats more quickly dried, and
the dust more freely picked up by the winds and distributed over
the adjacent uplands. It is a singular fact that the outwash from
the ice edge during the lowan and at some other stages, has left little
record of itself, unless the loess be its record. Gravel trains of moment
have not been found. The loess deposits seem to be, in some way, re-
lated to these stages, and both phenomena, perhaps, imply aridity,
strange as that may seem in a glacial epoch.
Opposed to the idea of a strict correlation with an ice stage, Shimek
has urged that the mollusks whose shells are the chief fossils of the
loess are such as inhabit the region to-day, and do not indicate, by
pauperate forms or otherwise, such climatic conditions as might natu-
rally be assigned to the near presence of an ice-sheet. A notable
dwarfing of the fossil species in the loess had previously been announced,
and regarded as an evidence of rigorous climate. Shimek suggests
the interglacial accumulation of the loess, and a careful test of this
hypothesis is merited. It is consistent with the fact that there is often
an aggregation of stones, pebbles, etc., on the surface of the till, below
the loess (Fig. 525). The concentration of stony matter here has been
interpreted as the result of surface wash, after the deposition of the
till below, and before that of the loess above.
The deposits in the West called loess seem to be in part fluvial and
in part eolian.
Bull. Phil. Soc. of Wash., Vol. IV., Bull. Geol. Soc. of Am., Vol. V, Science, New Ser.,
Vol. V; Shimek, Am. Geol., Vols. XXVIII and XXX, Bull. la. Lab. Nat. Hist., Vols.
I, II, and V, Proc. la. Acad. Sci., Vols. Ill, V, VI, and VII; Leverett, Am. Geol.,
Vol. XXXIII, and Mono. XXXVIII; Calvin, Bull. Geol. Soc. Am., Vol. X, p. 119;
Chamberlin, Jour, of Geol., Vol. V, 1897; Hershey, Am. Geol., Vols. XII and XXV,
1900; Fuller and others, Patoka and Ditney, Ind., Folios, U. S. Geol. Surv.; Davis,
Explorations in Turkestan, 1905
THE PLEISTOCENE OR GLACIAL PERIOD. 413
THE DURATION OF THE GLACIAL PERIOD.
The desire to measure the great events of geological history in
terms of years increases as the events approach our own period and
more intimately affect human affairs. The difficulties attending
such attempts are, however, formidable, and the results have an uncer-
tain value. At best they do little more than indicate the order of
magnitude of the periods involved. Geological processes are very
complex, and each of the cooperating factors is subject to variations,
and such a combination of uncertain variables introduces a wide range
of uncertainty into the results.
Efforts to determine the date and duration of the glacial period
fall mainly into two categories: (1) efforts to estimate the relative
duration of the several glacial and interglacial epochs, and (2) efforts
to measure in years the interval since the close of the glacial period.
(1) The best data for estimating the relative duration of the sev-
eral glacial stages are found in the region bordering the Mississippi
river, for it is there only that all members of the series are present.
There only also do they come into such relations with one another
as to furnish fair facilities for comparison. The criteria that have
been used in estimating relative duration embrace (1) the surface
erosion and the cutting of special gorges, (2) the depths of leaching
and weathering, (3) the internal changes, (4) the decomposition of
the pebbles and bowlders, (5) the amount of vegetable growth in
interglacial intervals, (6) the climatic changes indicated by floras
and faunas, (7) the times needful for the migration of faunas and
floras, particularly certain plants whose means of migration are very
limited, (8) the times necessarily required for advances and retreats
of the ice. and similar means. A few of these are subject to direct
measurement, as the relative amounts of erosion; but for the greater
part they are matters of judgment, in which the value of the result
is much affected by the personal equation.
A collation of the judgment of five of the glacial geologists who
have most studied the data in their most favorable expressions is the
basis for the estimates embodied in the following table. In this case,
the time-datum for each sheet of till is the stage at which it began
to suffer erosion, which, of course, would be slightly after the beginning
414 GEOLOGY.
of the ice retreat. The time-unit is the period which has elapsed
since the Late Wisconsin began to be exposed to erosion:
From the Late Wisconsin to the present -. . . 1 time-unit.
From the Early Wisconsin to the present 2 to 2J time-units-
From the lowan to the present 3 to 5
From the Illinoian to the present 7 to 9
From the Kansan to the present 15 to 17 1
From the sub-Af tonian to the present x "
So far as now known, the sub-Aftonian is everywhere buried by
later deposits, and the method of estimate by erosion is inapplicable
to it. Some hints of its relative age may be gained from the growth
of vegetation, and the development of the fauna and flora between
it and the Kansan, and from the superior amount of disintegration
and other internal changes which its material suffered; all of which
imply a considerable period anterior to the Kansan. If the sub-
Aftonian is equivalent to the very old drift of New Jersey and Penn-
sylvania (the Jerseyan), the erosion measure may be applied there,
with the result of indicating great antiquity.
The average of these estimates is not far from the geometrical
series 1, 2, 4, 8, 16. This symmetry is not presumed to have any
dynamic significance, but it may serve a mnemonic purpose. Subse-
quent studies have tended rather to increase than diminish the high
ratio of the earlier epochs. In particular, the studies of Calvin in
southwestern Iowa have strongly impressed him with the relative
greatness of the erosion of that region. It is not unlikely, however,
that this was in some measure dependent upon a more favorable topo-
graphic attitude, due to a relatively greater westward slope before
the western side of the Great Plains was lifted to its present elevation.2
Under full admonition as to the tentative nature of such estimates,
the figures above given may perhaps be taken as representative. There
is every presumption that they will need to be modified by further
researches, probably in the direction of extension.
1 A special estimate of the amount of the erosion suffered by the Kansan and Late
Wisconsin, respectively, in central Iowa, where they lie side by side under condi-
tions favorable for the comparison, gave Bain a ratio of 17 to 1. Geology of Polk
County, Iowa Geol. Surv., Vol. VI.
2 For estimates of period of time involved in certain glacial oscillations, see Taylor,
Jour, of Geol, Vol V, 1897.
THE PLEISTOCENE OR GLACIAL PERIOD. 415
(2) Of the efforts that have been made to measure in years the
post-glacial interval, those based upon the recession of Niagara and
St. Anthony Falls are the most important, and are all that can be
considered here.1 It is important, however, to note precisely what is
being measured. In both these instances, the measurement attempted
is the time occupied in the recession of the falls from the point of their
initiation to their present positions. It is as important to know when
they began their gorge cutting, as to know how long they have been
occupied in it. The gorge-cutting of the Niagara Falls could not have
begun until the Mohawk outlet of the ice-ponded lakes, previously
sketched, was abandoned, because the escarpment through which the
cutting subsequently took place was still submerged while the lake
discharged through the Mohawk valley. The time measured by the
Niagara cutting was only that which has elapsed since the ice-border
retired from the northeast flank of the Adirondacks sufficiently far
to permit the waters of the ancestral Lake Ontario to find an outlet
lower than the Niagara escarpment, and no very effective cutting
could take place until the waters were withdrawn to something near
their present level.
If the border of the ice-sheet at this stage (Fig. 522) is compared
with the border of the ice at the maximum Late Wisconsin stage
(Fig. 470), it will be seen that a retreat of the ice-border, measured
along the axes of the more protrusive lobes, of some 600 miles had
taken place. In the course of this retreat, about a score of morainic
ridges had been formed. Some of these appear to have represented
1 References on Niagara: Pohlman, Am. Assoc. Adv. Sci., Vol. XXXII, 1883,
and Vol. XXXV, 1887; Science, Vol. II, 1883, and Vol. VIII, 1886; Trans. Am. Inst.
Min. Eng., Vol. XVII, 1889, and Eng. and Min. Jour., Vol. XLVI, 1888. Wright,
Am. Jour. Sci., 3d ser., Vol. XXVIII, 1884; Sci. Vol. V, 1885; Bibliotheca Sacra,
1884 Proc. Am. Assoc. Adv. Sci., Vol. XLVII, Science, new ser., Vol. VIII; Am.
Geol., Vol XXII, 1898; Pop. Sci. Mo., Vol. LV, 1899, and Am. Jour. Sci., 3d ser.,
Vol. XXVIII. Gilbert, Am. Jour. Sci., 3d ser., Vol. XXXII, 1886; Science, Vol.
VIII, 1886; Proc. Am. Assoc. Adv. Sci., Vol. XXXV, 1887; Kept. N. Y. Com. State
Res. at Niagara, 6th Kept. 1890, and Chapter in Physiography of the United States.
Upham, Am. Jour. Sci., 3d ser., Vol. XLV; Jour. Geol., Vol. I, 1893; Am. Geol., Vol.
XI, 1893, and XVIII, 1896, and Pop. Sci. Mo., Vol. XLIX, 1896. Spencer, Am.
Jour. Sci., 3d ser., Vol. XLVIII, 1894, and Am. Geol., Vol. XIV, 1894; and Taylor,
Bull. Geol. Soc. Am., VoL IX, p. 84.
St. Anthony Falls: Winchell, N. H. Fifth Ann. Kept. Natl. Hist, and Geol.
Surv. of Minn., 1876; Geol. of Minn., Vol. II, 1888, Twenty-third Ann. Rept., 1894;
Southall, The Epoch of the Mammoth, p. 373.
416 GEOLOGY.
appreciable advances, as for example that brought out by the demon-
stration of Taylor that the Belmore beach of southwestern Michigan
was formed by such an advance later than the Arkona beaches that
stand below it. Phenomena connected with the moraines themselves
imply advances in other cases. It cannot therefore be assumed con-
sistently that the retreat of the ice from its maximum Late Wisconsin
advance to its position at the time the Niagara gorge began to be
cut, was a rapid, uninterrupted one. Rather must it be assumed
that the agencies that made for advance closely matched, and occa-
sionally over-matched, the agencies that made for retreat.
Before attempting to place a value upon the period so represented,
the time at which the gorge below St. Anthony Falls began to be cut
may well be considered also. From the normal methods of the glacial
streams of retiring ice-sheets, it is to be presumed that for a time sub-
sequent to the retreat of the ice-edge from the present location of
St. Anthony Falls, at Minneapolis, the outwash trains of the region
were being deposited, for the waters issuing from the edge of the ice,
so long as it lay on the southern slope, must apparently be presumed
to have been overburdened with glacial detritus which they were
throwing down along the courses of their channels to the southward.
Degradation may have taken place locally in the interest of a read-
justed gradient, but the general phenomenon must apparently have
been aggradation. This should have continued until the ice passed
beyond the northerly water-shed, or until the glacial waters, through
the agency of large lakes, were freed of their detritus. In direct sup-
port of this conception is the abundant evidence that the Mississippi
trench, as far down as the mouth of the Chippewa river, was filled
with glacial detritus to heights ranging from 100 to 120 feet or more
above the present river surface. Below the mouth of the Chippewa,
the glacial filling appears to have declined gradually to heights of
80, 70, 60, and 50 feet above the river, the last in the latitude of central
Illinois. Beyond this, satisfactory tracing of the terrace remnants has
not yet been made, but in the Mississippi valley below, there is a per-
sistent series of terraces ranging from 40 to 60 feet above the present
river, which have been tentatively regarded as the probable southern
representatives of this stage of aggradation. As far down as Natchez,
these terraces are fully 50 feet in height, which seems to imply that
the glacial filling reached a graded condition about the middle latitude of
THE PLEISTOCENE OR GLACIAL PERIOD. 417
Illinois, and thence to the Gulf took on a gradient comparable to that
of the existing flood-plain of the Mississippi.
When therefore the glacial aggradation ceased, it was first necessary
to clear out the Mississippi trench and lower the river before effective
cutting of the gorge below St. Anthony Falls could begin. The waters
of Lake Agassiz appear to have been an effective factor in this clearing
out, for, on account of the extent of the lake, the detritus of the
streams emptying into it from the ice was effectually deposited,
and the waters issuing from the lake were clear and capable of taking
up and rolling on the gravel and sand that filled the great trench. It
would appear from the configuration of the Minnesota valley, that by
the time Lake Agassiz ceased to discharge through the Minnesota
River, the filling of that river and of the upper Mississippi had been
cleared away to such a depth as to give the upper Mississippi an effective
fall for cutting the gorge below St. Anthony Falls. Perhaps the cutting
might have been gradually initiated somewhat before, but the time-
rate of the recent falls could not be properly applied to it until after
the full height of the fall was attained. The position of the ice-border
at the stage at which Lake Agassiz ceased to flow through the Minne-
sota river is not yet known, but it had retreated far enough to permit
the lake waters to escape by some northerly route. Under any proba-
ble hypothesis, this implies a retreat of the ice-edge some 700 to 800
miles from its extreme extension at Des Moines, a distance appre-
ciably greater than that requisite for initiating the Niagara gorge-
cutting.
Glacialists vary much in their estimates of the average rate of
retreat of the ice-border under such conditions. This retreat is of
course not measured by the rate of melting of the ice alone, but by
the difference between the rate of melting and the rate of advance of
the ice, and it is not to be forgotten that the evidence indicates that
the latter was at times superior to the former. If, however, to de-
velop a definite conception, and to aid every one in forming his own
judgment as to the probabilities of the case, we assume that there
were 200 days of effective melting in each year (which each will in-
crease or diminish according to his judgment), and if we allow that the
melting was sufficiently superior to the onward movement of the ice
to cause the ice-edge to retreat one foot per day (which each again
will modify to meet his judgment), and if no advance was made during
418
GEOLOGY.
the remainder of the year, we have a retreat of 200 feet per annum
(to us, an improbably high estimate). The total distance to be covered
by the retreat previous to the beginning of the- cutting of the Niagara
gorge is taken at some 600 miles, or
3,000,000 feet, and the time occupied
on the assumption of a retreat of
200 feet per year is 15,000 years,
at 300 feet per year, 10,000 years, or
at 100 feet per year, 30,000 years.
In the opinion of some glacialists
even the last represents too rapid
a retreat. The same rates applied
to the retreat pre-requisite to the St.
Anthony recession, give the results
17,000 to 20,000, 12,000 to 13,000r
and 35,000 to 40,000 respectively.
As already indicated and emphasized,
there are no means for a close deter-
mination of this factor.
If the length of the Niagara
gorge be divided by the average rate
of retreat since the successive posi-
tions of the Falls were located by
accurate surveys, the quotient is
about 7000. This result is, however,
subject to several qualifications which
have been well stated by Gilbert and
others, but which cannot be discussed
in detail here. The chief of these lies
in the belief that at the time of the be-
The ginning of the cutting of the gorge,
the waters of the upper lakes flowed
through the Nipissing valley into the
Ottawa (Fig. 522) , and thence to the
sea, leaving only the waters of the Erie basin to pass over the Falls. The
belief is also entertained that later, as the land to the north rose relatively,
an outlet was found through the Trent river, and that only at a com-
paratively late date were the waters of the Upper Great Lakes poured
FIG. 527. — The Niagara gorge.
American and the Horseshoe Falls
are shown on opposite sides of Goat
Island. (After Gilbert.)
THE PLEISTOCENE OR GLACIAL PERIOD. 419
over the Niagara Falls. Now the ordinary rate of erosion is measured
by a high power of the volume, when it induces an accelerated velocity
(Vol. I, pp. 115 to 123). Precisely how this general law is modified
in the case of falls is not known by direct experiment, but it may be
inferred from the phenomena of the falls under consideration. Since
the Horseshoe and American Falls separated, the latter has retired but
slightly from the position it occupied at the time of separation, while
the Horseshoe Fall has retired about ten times as far. With little
doubt this is due almost wholly to the superior volume of water poured
over the latter. This is further indicated by the form of the Horse-
shoe, since the volume per unit breadth is greater in the center than
on the sides. It is also shown by the recent extraordinarily rapid
recession at a point where the volume is exceptional.
In view of these considerations, Gilbert, Taylor, and Spencer have
urged that the cutting of the narrower portions of the gorge was prob-
ably the work of the relatively limited volume of water from the Erie
basin, and that the recession proceeded at a relatively slow rate on
this account, while the recession has been much accelerated since the
upper lakes joined their greater volume to that issuing from Lake Erie.
It is this accelerated rate that is used as the divisor in the simple com-
putation that gives 7000 years. In view of the probable rate of in-
crease of recession of the fall, due to increase in the volume of the
river after the drainage of the upper lakes was diverted to it, it is
thought that the simple quotient 7000 is to be multiplied several times
to give the true time-estimate. Spencer places the period at 31,000 or
32;000 years, and Taylor at 50,000 years as an approximate maximum.
There are, however, those who do not accept these qualifications and
who take appeal to other phenomena that cannot here be discussed.
The estimate of Upham, 7000 years, and that of Wright, 10,000 years,
are representative of this class. The mean of all the above estimates
is about 25,000 years.
From a comparison of the earlier and later surveys of St. Anthony
Falls, N. H. Winchell estimates the time of recession from the mouth of
the gorge to be about 8000 years. The chief qualification that affects the
rate of recession in this case seems to be the rapidity with which the
precipitation upon the catchment area above the falls was discharged.
This is but another application of the principle involved in the pre-
ceding case, for, given a certain amount of precipitation, the rate at
420 GEOLOGY.
which it is discharged determines its erosive effects. If it is poured
rapidly through its outlet, the effects are proportionately much greater
than if it be discharged equably throughout the whole season of pre-
cipitation. The headwater area of the Mississippi is particularly
affected by lakes, ponds, marshes, ill-drained flats, tortuous streams,
and other topographic features that even now greatly interfere with
the rapidity of discharge of the precipitation of the region. Since
the cutting began, the drainage lines have been deepened, widened, and
extended in the natural course of things, and the facilities for dis-
charge have been constantly improved. Presumably, therefore, there
has been a very appreciable increase in the rate of discharge of the
waters since the ice retreated, even without such aid as recent settle-
ment has brought. It follows that the effectiveness of erosion has
increased. It is the very latest rate of erosion that was determined
and used in the above calculation. The 8000 years should perhaps
be increased to 12,000 or 16,000 years.
It will be seen therefore that even in these cases of best data, there
are serious sources of qualification, and that these qualifications may,
in the judgment of experienced geologists, affect the results to the
extent of several hundred per cent. If the range of the estimates
of the Niagara be placed at 10,000 to 30,000 years, and if this be
added to the range of estimates for the time of retreat of the ice
before the falls came into existence, also 10,000 to 30,000, the result
is 20,000 to 60,000 years for the time since the Late Wisconsin ice-
sheet began to retreat. If the estimates for the St. Anthony gorge-cut-
ting be placed at 8000 to 16,000 years, and the estimates for retreat be
added, the range of estimates for the time since the beginning of the
Late Wisconsin ice retreat is 20,000 to 56,000 years. These may be
taken for a rough, wide-ranging estimate, such as it is, of the time
since the climax of the Late Wisconsin ice invasion. Now, using the
estimates in the table of relative duration above, and remembering
that we are multiplying the errors of the previous estimates, we reach
the following dates for the climaxes of the several ice invasions:
Climax of the Late Wisconsin 20,000 to 60,000 years ago.
" " " Early Wisconsin 40,000 to 150,000 " "
11 " " lowan 60,000 to 300,000 " "
" " " Illinoian 140,000 to 540,000 " "
" " " Kansan 300,000 to 1,020,000 " "
" " " Sub-Aftonian y to ' z " "
THE PLEISTOCENE OR GLACIAL PERIOD. 421
We place very little value on estimates of this kind, except as means
for developing a concrete sense of proportion.
Foreign.
In Europe, the succession of ice epochs and formations is not less
complex than in North America. The following table gives the classi-
fication of Geikie:1
XI. Upper Turbarian = Sixth Glacial Period.
X. Upper Forestian = Fifth Interglacial Period.
IX. Lower Turbarian = Fifth Glacial Epoch.
VIII. Lower Forestian= Fourth Interglacial Epoch.
VII. Mecklenburgian = Fourth Glacial Epoch.
VI. Neudeckian = Third Interglacial Epoch.
V. Polandian = Third Glacial Epoch.
IV. Helvetian = Second Interglacial Epoch.
III. Saxonian = Second Glacial Epoch.
II. Norfolkian = First Interglacial Epoch.
I. Scanian = First Glacial Epoch.
These several stages cannot now be correlated with confidence with
those of North America. According to Geikie's interpretation, the
ice of the Scanian epoch (perhaps = Jersey an) was less extensive than
that of the next epoch, and its deposits have been definitely recog-
nized in but few places. In the Norfolkian (Aftonian?) epoch, Great
Britain is thought to have been joined to the continent and to have
enjoyed a climate as mild as that of the present time. In the Saxonian
(Kansan?) epoch, the ice attained its maximum development and
covered the area shown in Fig. 528. In the deposits of the interglacial
Helvetian epoch, fossils denoting both cool and warm climates are
found, though perhaps not at the same horizon. The central European
flora of this stage indicates a climate milder than the present. In the
Polandian epoch, the ice-sheet was less extensive than in the Saxonian,
and the direction of ice movement was at variance with that of the
earlier epoch in many places. The deposits of the Neudeckian inter-
glacial epoch are partly marine and partly non-marine, and the faunas
1 Jour, of Geol., Vol. Ill, pp. 241-269.
422
GEOLOGY.
are temperate, or at least not arctic. The ice of the Mecklenburgian
(Early Wisconsin?) stage developed the stout moraines of North Ger-
many. At this time the ice-sheet of Scandinavia was not continuous
with that of Great Britain. The Lower Forestian epoch is repre-
sented by peat bogs and buried forests in northwestern Europe. The
land surface is thought to have been more extensive than now, and
to have enjoyed a milder climate. The next glacial epoch, the Lower
THE PLEISTOCENE OR GLACIAL PERIOD.
423
Turbarian, is represented by " valley moraines and corrie moraines "
in the higher regions, and by various sorts of non-glacial deposits
elsewhere. During this epoch, glaciers locally descended to the sea
in Scotland. In the last glacial epoch, according to the above classi-
fication, the ice was still more restricted.
The preceding classification is not accepted by the German geolo-
424 GEOLOGY.
gists, so far as it applies to Germany. They regard some of the sepa-
rate epochs of Geikie as stages of a single epoch, and would reduce the
number of glacial epochs to three, so far as their country is concerned.1
The deposits of several distinct glacial epochs have been recog-
nized also in the mountains south of the ice-sheet, especially in the
Alps.2
In other continents the glacial formations have been studied in
detail in but few places, but recent studies in Turkestan indicate that
the history of the glacial period in the Thian Shan Mountains was
complicated, five glacial epochs being recognized.3
The loess of Europe and Asia has already been referred to. The
eolian hypothesis of its origin seems to be gaining in favor, but other
opinions have been held,4 and still find advocates.
THE CAUSE OF THE GLACIAL PERIOD.
Many hypotheses respecting the cause of the glacial period have
been offered, but none of them has, as yet, commanded the general
assent of glacial investigators.
Almost all hypotheses appeal to a combination of agencies, but
each centers more or less on some one agency which gives character
to the hypothesis. Grouped by their characteristic agencies, they
fall mainly into three classes: (1) those which appeal to elevation,
the hypsometric hypotheses; (2) those which appeal to phenomena
outside the earth, or to the relations of the earth to other bodies, the
astronomic hypotheses, and (3) those which appeal to changes in the
constitution or movements of the air, the atmospheric hypotheses.
Hypsometric Hypotheses.
The hypothesis of elevation.5 — From the fact that alpine glacia-
tion is a function of elevation, it was natural that one of the earliest
hypotheses should postulate the lifting of the glaciated regions to
the snow-line by a wide-reaching deformative movement. Auxiliary
1Keilhack, Jour. Geol., Vol. Ill, pp. 113-125.
2 Penck, Die Alpen im Eiszeitalter.
3 Huntington, Explorations in Turkestan, Carnegie Institution.
4 8kertchleyandKingsmill,Q. J. G. S., Vol. LI (1895), pp. 238-254.
5 Dana, Manual of Geology, 4th ed., p. 970, and Upham, Am. Geol., Vol. VI, p. 327,
and Am. Jour. Sci., Vol. XII, p. 33.
THE PLEISTOCENE OR GLACIAL PERIOD. 425
geographic changes would be a natural consequence of such a move-
ment, and the effects of direct elevation and of attendant geographic
changes have been variously combined in the different phases the
hypothesis has assumed. As chief evidence of the elevation postu-
lated, the buried valleys of the sea coasts, especially those of the north-
ern latitudes, have been cited, and it is held by many advocates of
this hypothesis that the 4000 feet or more of elevation thought to
be indicated by the northern fiords, together with abetting geographic
changes, were competent to produce the Pleistocene glaciation. Those
who question this view doubt whether this elevation was contem-
poraneous with the ice development, and cite, as grounds for believing
that it was earlier, the magnitude of the erosion indicated by the fiords
compared with that which the glacial formations have suffered. They
cite also the direct evidences that the valleys formed during this period
of elevation were already present when the ice invasion took place.
On the other hand, they offer evidences that the land was often lower
than at present at certain important stages of the glacial period. It
is explained by the advocates of the hypothesis of elevation that the
glaciating effects must have lagged behind the elevation itself, and
that the accumulation of ice might well have produced depression,
and led to its own destruction.1 It is not, however, clear to those
who doubt the hypothesis that the glaciation should have lagged so
far behind the elevation as to result in the great discrepancy observed
between the erosion of the period of elevation, and the erosion of the
earliest drift-sheets. The hypothesis of elevation also encounters
difficulty in satisfactorily explaining the interglacial intervals which
are now well established by abundant evidence, and also in accounting
for the markedly mild climate of one or more of these intervals, which
seems to imply a disappearance of the ice at least as complete as that
of today. Unless some other agency than elevation be called into
play, it seems necessary to postulate that a great elevation of a large
part of two continents, followed by depression, was repeated as often
as there were great oscillations in the ice development. The advo-
cates of elevation have naturally questioned the adequacy of the evi-
dence that the oscillations of the ice-sheets were really great, and
they have usually held that the ice period was relatively short and
1 On this point see Jour. Geol., Vol. II, 1894, p. 222.
426 GEOLOGY.
simple. To escape the growing force of the evidence of frequent and
important interglacial intervals, the older phase of the hypothesis
has been amended by adding to elevation the main features of the
Crollian hypothesis next to be sketched, which carries a postulate that
involves climatic oscillations. The periods of these oscillations, however,
are equal, while the observed oscillations seem to be notably unequal.
The elevation hypothesis also encounters grave difficulties when
applied to the Permian glaciation of India, Australia, and South Africa,
because of their low latitudes, because of the great height apparently
required to furnish the necessary conditions for plateau glaciation,
and because of the great oscillations necessary to account for the marine
beds between the glacial beds. If the plateaus of Tibet and the Pamir,
ranging from 15,000 to 18,000 feet above the sea, are not glaciated
under present conditions, one cannot but wonder what elevation the
southern peninsula of India would have required in the Permian period
if elevation were the essential factor. No plateau outside the polar
circles is now glaciated, except as the ice is derived from adjacent
mountains, no matter what its relations to sea or land, to winds or
currents, to moisture or aridity or other conditions. The observa-
tional basis for assigning the glaciation of a half of the North Ameri-
can continent to any elevation that can fairly be assigned to it, during
either the Permian or Pleistocene period, is thus not as broad and
firm as could be desired for a satisfactory working hypothesis.
Astronomic Hypotheses.
CrolPs hypothesis.1 — A semi-astronomical hypothesis was advanced
by James Croll in the latter part of the last century, and for a time
gained very wide acceptance in Europe, and found not a few adherents
in America. The hypothesis is founded on variations in the eccen-
tricity of the earth's orbit, combined with the precession of the equi-
noxes, together with the effects of meteorological and geographical
influences, particularly the configuration of the Atlantic Ocean.
The orbit of the earth is slightly elliptical, and this ellipticity is
subject to variations on account of the varying positions of the planets,
1 Climate and Time in their Geological Relations; a theory of secular changes
of the earth's climate, by James Croll, 1890, pp. 312-328; also Climate and Cosmol-
ogy, 1889, and The Cause of the Ice Age, Sir Robt. Ball, 1893.
THE PLEISTOCENE OR GLACIAL PERIOD. 427
the upper limit being an eccentricity of 0.07. It is not claimed that
this alters the total amount of heat received by the earth, or by
either hemisphere, or even the proportions received during the periods
between the equinoxes, which, according to Ball, are in the ratio of
63 for the summer to 37 for the winter, but that the distribution of
heat within these periods is markedly affected by the shortening or
lengthening of the two seasons, according as they fall in the peri-
helion or the aphelion portion of the orbit. In the perihelion
portion there is a short season with much heat per hour, and in
the aphelion portion a long season with less heat per hour. The
precession of the equinoxes causes the seasons to shift relative to the
perihelial and aphelial points. At present the earth is nearest the
sun in our early winter, or in the early summer of the southern hemi-
sphere. In 10,500 years the earth will be nearest the sun in our early
summer, or the early winter of the southern hemisphere. We shall
then have a shorter summer with more solar heat per hour, and a
longer winter with less heat per hour. There have been differences
of opinion as to how this change in the distribution of heat would
affect glaciation. The Crollian hypothesis is built upon the belief
that snow accumulation would be favored by the long winters, and
snow-melting reduced by the short summers, notwithstanding their
greater heat per diem.
It is conceded that the amount of eccentricity at present is too
small to produce a very appreciable effect, otherwise we would have
a glacial epoch now in the southern hemisphere. The eccentricity
fluctuates in a very complicated way because of the varying attraction
of the other planets on the earth, whose lines of attraction are con-
stantly shifting, and are usually diverse and more or less mutually
neutralizing. At long intervals, the planets pull measurably together and
give relatively high eccentricity, but this never exceeds about four
times the present amount. The hypothesis assumes that the rela-
tively high eccentricity that is attained at these periods is sufficient
to produce the essential conditions of the glacial period.
It is admitted that these astronomical relations are insufficient in
themselves to produce the glacial effects observed, and so certain ter-
restrial conditions are made important elements in the working phase of
the hypothesis. Prominent among these, it is held that the zone of the
trade-winds and the thermal equator would be shifted from the gla-
428 GEOLOGY.
elated hemisphere toward the warmer one, and that this shifting would
turn a large part of the warm equatorial waters away from the cooler
hemisphere, intensifying the direct astronomical effect, while the warm
water thus carried in excess into the warmer hemisphere would intensify
the evaporating effects, and induce a mild and moist climate. Croll
urged that this shifting would be peculiarly effective in the Atlantic,
because of the angular form of the eastern coast of South America,
and the critical position of Cape St. Roque relative to the equatorial
currents. He held that a few degrees of southward shift of the trade-
wind belts would throw a large part of the equatorial current south of
Cape St. Roque, and turn it into the South Atlantic, greatly reducing
both the existing contribution to the Gulf Stream and its auxiliary
climatic effects, while, on the other hand, a northward shift, when the
southern hemisphere was passing through its cold period, would throw
nearly all the equatorial current north of St. Roque, and thus intensify
the ameliorating conditions of the North Atlantic, and give a mild,
moist interglacial epoch to the northern hemisphere. On this account
especially he held that glaciation preponderated about the North
Atlantic, and was less pronounced in other high latitudes.
A peculiarity of the hypothesis is that (1) the glacial epochs it
postulates alternate between the northern and the southern hemi-
spheres, and (2) that they are limited in duration to an appropriate
fraction of the precessional period (21,000 years). This appropriate
fraction is probably about that which effective winter bears to the
whole year, for in the course of the precessional period, which may
be conceived as an astronomical year, the attitude of the earth would
pass through a stage of neutral distribution of heat between the gla-
cial and the deglacial stages, very similar in nature to the con-
ditions that produce our spring and fall. In the middle latitudes, the
effective winter would perhaps occupy 5000 or 6000 years; in the high
latitudes, one half or more of the precessional year, while in the equa-
torial belt, there would probably be little or no glaciating effects.
These peculiarities of the hypothesis afford a means of testing it. If
it be true, the glacial episodes should bear evidences of equal length;
they should all be short, and they should be equally distant from each
other in the same period of eccentricity. If the computations of the
periods of eccentricity published by Croll are founded on adequate
data (which has been questioned), there could only be a few alternations
THE PLEISTOCENE OR GLACIAL PERIOD. 429
of glaciation within a given period of high eccentricity, while none
of them could be more recent than 60,000 years; indeed, Croll consist-
ently placed the close of the glacial epoch 80,000 years ago.
The extended and critical glacial studies of recent years seem to
show that the intervals between the different invasions are very un-
equal in time relations, and that the most recent is relatively young.
It has also been found that glaciation was notably extended beyond
its present limits on the lofty mountains of the equatorial regions.
The progress of inquiry seems, therefore, to have weakened, rather
than strengthened, the grounds of presumption in favor of this attrac-
tive hypothesis.
To appreciate the difficulties that arise from the shortness of the
epochs of the Crollian hypothesis, it is to be observed that the Labra-
dorean and Keewatin ice-sheets pushed out from what appear to have
been their centers about 1600 and 1500 miles respectively. In making
this estimate the centers are placed as far south as a fair interpreta-
tion will permit. If for a generous safety margin we place these centers
of the initial snow-fields 500 miles farther to the southward, the edge of
the ice-sheets had still to creep 1000 miles during the advancing stage of
glaciation. To this is to be aclded its haltings and its retreating stages.
It is to be noted that the advance of the frontal border of this ice-
sheet is radically different from the movement of the ice itself, since
the advance of the margin is only the difference between the rate of
the ice movement and the melting of the margin. If one foot per
day be allowed for the advance of the margin — an estimate much
beyond the probabilities — it would take more than 14,000 years for the
ice-edge to reach the extension observed. This is two thirds of the
whole precessional period. If the safety margin of 500 miles be included,
as it perhaps should be, and it be assumed that the accumulation of
the central portion to a thickness sufficient to give effectual motion
required as long a time per mile as its subsequent extension (since
it took place in the initial stages of the glacial winter when its effective-
ness was doubtless relatively small), the whole precessional period
or more would be occupied in extending the ice the required distance.
Nor is the difficulty essentially escaped by assuming that the snow-
field grew up simultaneously over the whole area, or some large part
of it, for numerous bowlders are found 600 or 700 miles from their
nearest assignable sources, and 800 to 1000 miles or more from their
430 GEOLOGY.
probable sources. To allow time for the residue of winter snow above
summer melting to build itself up to a height capable of giving effective
motion, and then to allow time to carry drift this great distance at
any probable rate of motion, taxes the hypothesis very severely to
say the least, for a high rate of motion probably cannot be assigned
safely.
There is a widespread misapprehension as to the average rate of
movement of the ice-fields of Greenland, which are almost our only
available field of observation on the motion of continental glaciers.
In certain fiords that lead out from great basins into which broad
fields discharge their ice and their surface waters, and thus furnish the
conditions for an extraordinary rate of movement, the rate of motion,
at least during summer, is unusually high, and these exceptional cases
have been taken as representative of the movement of the border
of the inland ice. This is very far from being true. The average
movement for the whole border of the ice field is quite certainly less
than one foot per day, and is more likely less than one foot per week.
The melting and evaporation at the edge of the ice fields of Greenland
cut it back only a few feet per year, because of the shortness of the
season and the covering of annual snow. Probably the wastage does
not reach ten feet per annum. It is certainly much less than 10 feet
in northern Greenland. If 12 feet be allowed for this, there should
be an average advance of the edge of the ice of 40 feet, on the basis
of one foot per week onward movement. This amount of advance for
the 1400 to 1600 miles of ice border tributary to Baffin's Bay, would
require the discharge of more than 1000 icebergs annually, averaging
100 feet in length and 300 feet in breadth, to remove the excess of ice
and keep the margin of the ice-fields stationary, and this number of
icebergs of these average dimensions exceeds the estimates of Rink
and others. If the estimate were raised to one foot per day, the num-
ber of discharging icebergs would obviously greatly exceed the observed
number. If the rate of advance be approached from the point of
view of precipitation, computations show that either an enormous
•snowfall over vast regions or an almost total absence of melting and
evaporation must be postulated to account for the building up of the
great Pleistocene ice-sheets, and for developing their observed radial
movements within such limited periods of time as the Crollian hypoth-
esis requires.
THE PLEISTOCENE OR GLACIAL PERIOD. 431
The Crollian hypothesis encounters further serious difficulties when
applied to the Permian glaciation of India, Australia, and South Africa,
because of their low latitudes. The effect of eccentricity should be
felt chiefly in the higher latitudes, and should be a vanishing quantity
in the tropical belt. It is not clear how glaciation in the vicinity of
the tropics could be explained on this basis, particularly in the Paleo-
zoic era, unless the postulates of the atmospheric theory be also intro-
duced to furnish favorable working conditions.
Other astronomical hypotheses. — Attempts have been made to
found other theories on the eccentricity of the earth's orbit, and also
to found them on variations in the obliquity of the ecliptic; but none of
these has gained much acceptance. They have not been worked out
with the care and detail which Croll gave to his hypothesis. They
encounter most of the difficulties of the Crollian hypothesis, but in
somewhat different forms.
There have been speculations upon the possible passage of the
earth through cold regions of space, but there is no astronomical basis
for them.
The recent determination of Langley and Abbot that the heat
emitted by the sun varies as much as 10% within a short period, is
very suggestive ; but a short-period variation really has no direct appli-
cation to a problem which requires a variation-period of tens of thou-
sands, if not hundreds of thousands, of years.1
The hypothesis of a wandering pole. — It was early suggested that
the axis of the earth may have been shifting its geographic position
and that the Pleistocene glaciations were but polar glaciations of the
existing type, distributed over northeastern North America and north-
western Europe by an excursion of the pole through 15° or 20° of lati-
tude. So long as the theory of a thin crust resting on a liquid nucleus,
and capable of sliding over it, perhaps under the differential influence of
the tidal pull, was accepted, the mechanical difficulties of this hypothe-
sis did not seem insuperable; but if an effective rigidity of the body
of the earth be accepted, as now seems almost necessary, the dynamic
obstacles become extremely formidable, for no agency capable of pro-
ducing such a change in the axis seems rationally assignable. When
a few years ago it was discovered that changes of latitude were actu-
1 Astrophysical Jour., Vol. XIV, 1904, pp. 305-321.
432 GEOLOGY.
ally taking place so rapidly as to be detectible in the course of a few
months, and when it was found in the progress of field studies that
the Alaskan-Asiatic side of the northern hemisphere was not gener-
ally glaciated, as the Atlantic side was, there seemed some little hope
that a wandering pole might offer the solution of the glacial puzzle.
The polar movement, however, proved to be limited to a returning
curve of very small radius, without evidence of secular wandering.
Geological research also failed to show that there was the northward
shift of the warm zones on the unglaciated side of the globe which
the hypothesis required.
Atmospheric Hypotheses.
In the discussion of the origin and nature of the early atmosphere
and its dependence on feeding and depletion (Vol. II, p. 93), we have
endeavored to develop a conception of the general atmospheric con-
ditions of all the ages that would at least not be inconsistent with
glaciation in the early Cambrian, or the Permian, or at any other stage
in the earth's history at which a suitable combination of conditions
might be presented.
I. Variations in depletion the working factor. — In the discussion
of the problems of the Permian, we have endeavored to connect atmos-
pheric conditions with causes springing fundamentally from defor-
mation of the earth, and entering into the complex outworkings of
the periods following such deformations.
The deformations of the Pliocene may be presumed to have pro-
duced effects on the atmosphere similar to those produced by the post-
Carboniferous deformations. The general discussion there given (Vol.
II, p. 658) may therefore be regarded as applicable to the Pleistocene
glaciations, so far as the general atmospheric conditions are concerned,
merely recalling (1) that the oceanic circulation was interrupted by
the extension of the land; (2) that vertical circulation of the atmos-
phere was accelerated by continental and other influences; (3) that
the thermal blanketing of the earth was reduced by a depletion of
the moisture and carbon dioxide in the atmosphere, and that hence
the average temperature of the surface of the earth and of the body
of the ocean was reduced, and diversity in the distribution of heat
and moisture introduced. The general conditions for glaciation are
THE PLEISTOCENE OR GLACIAL PERIOD. 433
thus supposed to have been supplied, conditions without which all
more special and local causes would be inoperative.
Two serious problems, however, remain: (1) the localization of
the Pleistocene glaciation, which, though not so remarkable as that
of the Permian period, was yet very extraordinary, and (2) the period-
icity expressed in a succession of glacial and interglacial epochs which
formed a declining series of very unequal lengths.
1. Localization. — The localization 1 is assigned to the two great
areas of permanent atmospheric depression that have their present
centers near Greenland and the Aleutian Islands respectively (Figs. 530
and 531). It is within these permanent cyclonic areas that the excep-
tional glaciations of Greenland and Alaska occur at present. There
is also a remarkable correspondence between the border of the ice-
sheets and the courses of the moving storms on the borders of these
permanent cyclonic areas. It is also notable that the great ice-lobes
converged toward the area where the storm-frequency is now greatest.
It is not a little remarkable that the ice-sheets after their several retreats,
and perhaps entire disappearances, should have advanced repeatedly
in nearly the same forms and to nearly the same extents, though in
some particulars their habits otherwise were noticeably unlike. All
these and many minor facts are associated in theory with these per-
manent " lows " and the related storm- tracks. These features are
presumed to have been extended and intensified during the glacial
stages, but to have retained the general relations and configurations
they now possess. The basal cause of these features is probably to
be found in the configuration of the land and water of the northern
hemisphere.
2. Periodicity. — The periodicity of glaciation under this hypoth-
esis is assigned to a rather complex interaction of a combination of
agencies which is not susceptible of brief statement without more
qualification than our limits will permit, if it is to be wholly accu-
rate and fully protected against misinterpretation; but the leading
features may be sketched and the necessary qualifications must be
taken for granted.
The basal conception is that, under general conditions favorable
1 An Attempt to Frame a Working Hypothesis of the Cause of Glacial Periods on
an Atmospheric Basis. Jour. Geol., Vol. VII, 1899, pp 752-771. See also discussion
of localization under Permian, Vol. II, p. 674.
434
GEOLOGY.
THE PLEISTOCENE OR GLACIAL PERIOD.
435
436 GEOLOGY.
for glaciation, certain of the agencies involved became dominant and
tended to intensify and accelerate glaciation for a time, until they
either pushed the effects to an extreme from which a reaction was
inevitable, or they exhausted themselves temporarily, while other
agencies of opposite phase, which had been subordinate until then,
became dominant and forced a reaction.
When a reaction was set up, it in like manner was pushed to an
extreme, and deglaciation extended beyond the point of equilibrium
for the average conditions. And so oscillations beyond and short
of the mean state, gave a rhythmical phase to the glaciation of the
period. The rhythm, we learn from observation, took the form of
a series of sub-equal oscillations with declining time-intervals. There
seem to have been no great differences in the amplitude of the ice
advances. Observation does not permit us to speak as confidently
of the extents of the recessions. It is important to note that the fun-
damental or general conditions remained effective throughout the
period, and that the oscillations are regarded only as rhythms super-
posed on these general conditions. The more intense phases of these
rhythms were, however, the only portions of the series that recorded
themselves in glaciation near the borders of the glaciated areas, and
were perhaps the only portions that recorded themselves in continental
glaciations at all. The retrocessional phases may have been recorded
only in cool climates in high latitudes, and in glaciation at high alti-
tudes.
Among the specially intensifying agencies that are thought to
have pushed glaciation to its climaxes, the following are recognized:
1. The higher carbonation of the ocean necessary to bring its car-
bon dioxide into equilibrium with that of the atmosphere at the
lower temperature that had been induced by the general conditions,
especially in the high latitudes. This lower temperature of the water
gave the sea a higher coefficient of absorption of carbon dioxide. (See
previous discussion under Permian, Vol. II, p. 665.)
2. A special process of super-carbonation of the ocean through
the agency of freezing in high latitudes, which cooperated with the
above.
3. A reduction of the organic extraction of lime and the other bases
of the bicarbonates, which otherwise would have freed carbon dioxide.
4. An increased reflection from the snow-fields and hence a reduced
THE PLEISTOCENE OR GLACIAL PERIOD. 437
retention of solar radiation, abetted by an increase of ice-clouds and
frozen fogs, which have high reflective power, low specific heat, and
low diathermacy.1
5. A progressive reduction of the moisture in the air, and hence a
decrease of its blanketing effects.
6. Some minor agencies that may be passed by.
These were opposed by the following:
1. The giving forth of carbon dioxide from the ocean because of
the reduced pressure of the carbon dioxide of the air, as the latter was
consumed.
2. A reduction of the contact area between land and air by the
growth of the ice-fields, and hence the checking of the carbonation of
the rocks.
There was a residual effect arising from changes in the amounts of
vegetal growth, animal life, and organic decay, that was felt on the one
side or the other, but it is not easy to strike the balance. Probably,
the ratio of animal life to vegetal growth was rather higher than before,
as the carbon dioxide declined, as the relative amount of oxygen
increased, and as the cold increased; but decay was probably also
checked, and the formation of peat and similar residues of organic
matter promoted. On whichever side it may have fallen, the balance
was probably not very important.
It will be noticed that these opposing agencies came into effect
only after the glaciating agencies had done such part of their work
as brought these opposing agencies into activity; and hence they
lagged behind the effects they tended to offset. For example, the
diffusion of carbon dioxide from the ocean to the air requires time.
Its effects could only be felt some time after those of the cause of
the diffusion. Besides, interchange between the main body of the
ocean and the air was especially retarded by the surface layer of fresh
uncarbonated water that came from the melting of sea-ice, and even
of the land-ice, and by the superficial layer especially affected by pelagic
life.
The checking, at length, of the glacial acceleration, is assigned to
the following agencies, particularly the first:
1. The completion of the higher carbonation of the ocean, followed
1 The specific heat of ice is 0.504, that of water being unity. For diathermacy,
see Preston's Theory of Heat, pp. 466, 467, 1894.
438 GEOLOGY.
by a reversal of the process, in which the ocean gave forth more carbon
dioxide than it received.
2. The cumulative effects of the ice-covering in reducing the car-
bonation of the rocks.
When once the extension of the glaciation had been checked and a
retrocession begun, the following agencies are thought to have abetted
it, and forced it, in turn, to an extreme.
1. The reversal of the oceanic action, by which it gave out in the
warm regions more carbon dioxide than it absorbed in the cold regions,
and thus lost its higher state of carbonation.
2. The increase of the secretion of lime in the ocean, setting free
the second equivalent of carbon dioxide of the calcium bicarbonate.
This was due to increasing warmth of the ocean and to the spread
of the shallow sea-border on the land as the result of the return to
the ocean of the water previously locked up in the ice, the warmth
acting both through dissociation and through lime-secreting organisms.
3. An increase in the moisture hi the air, and hence an increased
absorption and retention of solar radiation.
4. A reduced reflection from the snow-fields, ice-clouds, and frozen
fogs, and the substitution of the more thermally absorbent dark earth,
water-clouds and fogs.
The cumulative effects of these and some minor agencies are pre-
sumed to have pushed the glaciation back to a state appreciably beyond
that required by the average effects of the agencies involved, and
hence to have prepared the way for a new stage of aggressive glaciation.
The agencies are thought to have been competent to produce entire
deglaciation of the lowlands, in the longer interglacial epochs. They
are not thought to have been able to restore the deep oceanic circu-
lation to the pre-glacial state, but only to check and change the car-
bonating effects.
In all this period of oscillation it is assumed that there was an
average supply of atmospheric material from the original sources,
external and internal. This might of course have varied, and such
variations must be taken into account as modifying and possibly even
interrupting the processes just outlined; but in discriminating the
effects of the latter, an average contribution from the sources of supply
is assumed. It is possible to build up a hypothesis of climate on
the variations of atmospheric supply, as will be noted later.
THE PLEISTOCENE OR GLACIAL PERIOD. 439
Only a selected portion of this complex process can be further
discussed here. The factor that most probably controlled the periods
of the glacial oscillations, as it seems to us now, was the reversal in
the carbonation of the ocean, and this seems to have bearings of value
bevond this immediate problem.
Let the climatic conditions of the Tertiary period, when figs and
magnolias grew in Greenland, be taken as the point of departure. At
that time, as apparently at all times, the evaporation and the abso-
iiumidity of the air in the low latitudes was greater than in the
high latitudes. The general circulation of the atmosphere between
the equatorial and polar regions resulted in a loss of humidity in the
latter regions, and a gain to the ocean, whose surface was slightly
raised and freshened. This gave rise to superficial currents toward
the warm zone, to restore the equilibrium. These were gradient cur-
rents, for the added waters, though cold, were lighter than the ocean
brines.1
There was inevitably some mining of the fresh and salt water, and
some of the latter was also carried toward the warm latitudes. In the
warm dry latitudes, the excess of evaporation gave rise to increased
salinity and density, and the denser salt waters are assumed to
have sunk and spread poleward, constituting a counter-current to
balance the salt-water element of the equatorward currents. The
fresh-water element of the surface circulation had its counterpart
in the atmospheric circulation. The flow initiated in the evaporating
zone was a density current, due to salinity, notwithstanding its superior
warmth. This warm dense water, descending and flowing poleward,
must at length have been forced to the surface in high latitudes, and
contributed its warmth to them. This is assigned as one reason for
the warm temperatures of the high latitudes in those periods when
this kind of deep-sea circulation prevailed.
The validity of this conception of the deep-sea circulation in such
periods is based on the conviction that superior evaporation in the
low latitudes was more efficient in inducing high density, than the
inferior temperatures in the high latitudes. That this was at least
1 It is to be borne in mind throughout this discussion that an increase of salinity
» likely to be more effective in increasing density than is a lessening of the tem-
perature. Because of the peculiar behavior of water near the freezing-point, the
giauliy at the freezing-point of salt-water is about the same as at 12° C.
440 GEOLOGY.
possible may be inferred from the fact that the range of density-effects
for a range of temperature of 30° C., is about 0.004, while the range
due to salinity may be 0.028 or more. The probable ranges were,
however, much less wide apart, and this circulation is not a deduction
wholly beyond question.
The water thus thought to be carried down and poleward from
the equatorial regions was carbonated under the conditions of equi-
librium then prevalent in the low latitudes. Because of the high
temperature there, the carbonation of this poleward flowing water
was relatively low, and the main body of the ocean would be sub-
carbonated, i.e., carbonated below an ideal equilibrium for the aver-
age temperature, for the average content of carbon dioxide in the
air, and for the average carbonates in the sea. In the glacial period,
when freezing in high latitudes was brought on by the general lower-
ing of temperatures, the salts and gases of the sea-water must have
been largely forced out of the ice, and passed into the layer of water
next below, which thus became super-charged with salts and carbon
dioxide.1
In being cooled before freezing, the sea-water, under normal con-
ditions, absorbed carbon dioxide, because the coefficient of absorption
for carbon dioxide was raised by the cooling. The sea-water should,
therefore, have been more highly charged with this gas than the aver-
age ocean even before the freezing took place, and hence was specially
super-carbonated.
The layer of water below the sea-ice, thus super-carbonated and
rendered heavy by super-salinity, tended to descend and flow toward
the equator. Thus the depths of the ocean were slowly rilled with
cold, super-carbonated water, displacing the previous warm, sub-
carbonated water.
1 A portion of the carbon dioxide thus concentrated probably escaped into the
air when opportunity was afforded by seams and lanes in the ice, but the greater
part doubtless followed the course of the dense water in which it was dissolved. An
illustration of the incidental effects of this process is probably given in the exception-
ally high content of carbon dioxide found in the air at certain times in Grinnell Land
and Greenland. (Moss, Notes on Arctic Air, Proc. Roy. Dublin Soc., Vol. II, 1880,
and more fully, Krogh, Abnormal CO2 percentage in the air of Greenland, etc., Med-
delelser om Gronland, Vol. XXVI, 1904, pp. 409-411.) At present the Arctic
ice drift is concentrated toward Greenland and the islands west of it, and the waters
below are doubtless more or less carried with the ice and discharge some of their
super-charge of carbon dioxide into the air.
THE PLEISTOCENE OR GLACIAL PERIOD. 441
But as soon as the great depths were filled, and these super-car-
bonated waters themselves rose to the surface in the warm zones, they
must have given forth not only the super-charge of carbon dioxide
they then retained, but, because the coefficient of absorption was
lowered by the rise of temperature, they must have given forth a por-
tion of what was their normal content in the cold zone. It is obvious,
therefore, that as soon as the new circulation was well established,
its output of gas in the lower latitudes must have equaled or sur-
passed its intake in the higher, incidental qualifications aside. The
circulation was then no longer a source of atmospheric depletion. The
whole ocean body had been raised to the higher state of carbonation
required by the lower temperature. Not only this, but the process
was reversed; for the intake in the high latitudes had been decreasing
since the carbon dioxide of the atmosphere had been declining as the
result of the very process of loading up the ocean, and the surface-
waters that entered the freezing zone were lower in carbon dioxide
than they had been at the start, and hence the concentration by freezing
was less effective. This was not true of the salts, so far as this process
was concerned, and hence the circulation was not effected by the
reduced carbonation. At this stage, therefore, the atmosphere began
to be enriched in carbon dioxide, and the reverse swing of the oscil-
lation was inaugurated.
If this reasoning be valid, the length of the previous stage of higher
carbonation of the ocean becomes a matter of concern. It is prob-
able that the deep-sea circulation is affected by other factors than
those of low temperatures and increased salinity in the polar regions.
It has been thought that the winds of the North Atlantic tended to
heap up the waters in the Arctic Ocean, and thus to induce a return
current below, in addition to the recognized Labrador current at the
surface. While this may be true in this instance, because of the con-
figuration of the North Atlantic, it is not obvious that, for the whole
world, the pole-ward winds would be more effective on the ocean sur-
face than the opposite winds. Rather might one suppose that the
colder air moving equator- ward would, on the whole, flow more largely
at the bottom of the atmosphere, and be the more influential on the
currents of the ocean. If the winds, on the whole, promote deep-seated
circulation from high to low latitudes, they would shorten the periods of
carbonation and decarbonation; if the opposite, they would lengthen them.
442 GEOLOGY.
The depths of the ocean are now filled with water but little above
the freezing-point, which implies a deep-seated movement from the
polar regions. This goes to show that diffusion, mechanical mixture,
friction, agitation transmitted from the surface, tidal and earthquake
motions, and the internal heat of the earth, all combined, do not more
than slightly modify the dominance of this circulation as a means of
determining the temperature of the deep sea, and hence there is still
less reason to question its dominance in determining the saline and
gaseous content of the deep-sea waters, for only the first two of the
agencies tend to diffuse these constituents. The form of the super-
carbonation is indeed changed by the solution of minute calcareous
shells that fall from the ocean surface, and are dissolved before they
reach the greatest depths, as shown by the Challenger investigations;
but the carbon dioxide so used becomes free again when the calcium
carbonate is again secreted by plants or animals. The point of moment
here is that the process is essentially one of circulation, and is not
essentially modified by diffusive processes, and hence that the time-
period is closely measured by the great cycle which carries the whole
body of the ocean through its concentrating action. The relatively
rapid surface circulation of the ocean has little to do with this.
According to the observations of Peary 1 and Nansen 2 the first
season's freezing at the points of their observations, which may be
called mid-arctic, reaches depths of 4 to 8 feet. That of subsequent
seasons, when the old ice remains, is appreciably less. In the center
of the frozen seas, the old ice forms a persistent covering. If a layer
of new ice as much as 5 feet in thickness were formed annually over
an area of 9,000,000 square miles — about the area of the Arctic and
Antarctic Oceans combined, according to Murray — a mass of water
equal to that of the whole ocean would pass through the freezing
process in about 33,000 years; if the annual layer were 3 feet thick,
in about 55,000 years; if 2 feet, in about 83,000 years. This implies
a movement equal to the amount of freezing only, and a correspond-
ingly high concentration of salt and gas. A greater movement and
a less concentration are much more probable, and hence a shorter
period for the super-carbonating epoch. There is a considerable list
of modifying conditions, the most of which would apparently tend
1 Personal information.
/ 2 Scottish Geog. Mag., Vol. XIII, 1897, p. 240.
THE PLEISTOCENE OR GLACIAL PERIOD. 443
to reduce the period, and the uncertainties of this estimate are not
unlike those relative to the length of a glacial advance or retreat, but
the period thus estimated is of the same general order of magnitude
as that of the glacial stages, and nothing beyond such a similarity in
order of magnitude is to be expected. During this process of higher
carbonation of the ocean, the advance of the ice was reducing the
area of the land exposed to carbonation, and was thus reducing the
carbonation of the rocks. This checking of the carbonation on the
land cooperated with the reversal of sea-action in the inauguration of
an ice retreat.
As warmth increased there should have been, normally, an increase
of lime-secreting plants and animals, and these would have secreted
more lime individually, as a rule, setting free more of the second equiv-
alent of carbon dioxide of the calcium carbonate. The moisture in
the air should have increased with the increase of warmth and the
melting of the ice-fields. This new combination gained in force as
the ice was removed. It is assumed that the cooperative force of this
combination, once in dominance, maintained its superiority over the
opposing agencies until the ice-sheets were largely or wholly removed,
and the freezing that had inaugurated the oceanic super-carbonation
ceased to be effective.
When the full land-surface was again exposed .to carbonation, and
the air had been re-enriched in carbon dioxide, and the oceanic cir-
culation had carried the most highly carbonated portions of its waters
to the surface in low latitudes, and had begun to bring up the rela-
tively low carbonated portion that had descended in high latitudes
after the carbon dioxide had become depleted to its lowest state, the
conditions were ripe for a new process of depletion and glaciation
under conditions closely similar to the previous one. The process
could thus be repeated until the general conditions that brought on
the glaciation ceased to be effective, and the conditions for re-inau-
gurating a movement toward a mild uniform climate were restored.
It is not presumed, however, that the oceanic circulation was reversed
in the interglacial stages, but that the super-carbonation in the high
latitudes was reduced to an ineffective measure, or stopped entirely.
In a climate that permitted pawpaws and osage oranges to flourish in
eastern North America above latitude 43°, and induced lions, leopards,
hippopotamuses, etc., to invade the middle latitudes of Europe, an
444 GEOLOGY.
essentially complete suspension of the formation of sea-ice may be
assumed with much reason. Obviously, the succession of such gla-
ciations and deglaciations could only continue so long as the general
conditions that brought on the glaciation continued to prevail. So
soon as they passed away, the oscillating series ceased.
This hypothesis is dependent on the efficiency of carbon dioxide
and water-vapor as thermal absorbents. While this is conceded for
the water-vapor, and measurably for the carbon dioxide, the quantita-
tive efficiency of the latter has been questioned. This has been touched
upon in the Permian discussion, and it will only be added here, that
if a lowering of the average temperature of the globe from 5° to 8° C.
below the present temperature would be sufficient to produce the general
conditions of glaciation, as has been estimated, a direct efficiency of car-
bon dioxide to the extent of 1° or 2° C., with the cooperation of the
water- vapor and accessory agencies, would probably produce the requisite
effects. In the Sahara, the lowness of the moisture in the air often
permits the temperature to fall from mid-day heat to 0° C., during the
night. If there were no atmosphere at all above the Sahara, the tem-
perature would undoubtedly fall 100° to 200° C. more during the
night. That it does not do so is due to the efficiency of the remaining
constituents of the atmosphere. Their value as cooperating factors
has been greatly underestimated. By mathematical computations,
based on Langley's observations on the heat received from the moon,
Arrhenius some time since deduced a much higher estimate of the thermal
efficiency of the carbon dioxide of the atmosphere than the glacial prob-
lem seems to require.1 More recent experimental determinations give
notably lower results. The later results of Arrhenius2 himself seem
still to be more than sufficiently high, while those of Rubens and
Aschkinass 3 and of Angstrom 4 do not seem fatally low, though they
have been so interpreted.
Objection has been made to the sufficiency of the consumption of
carbon dioxide to produce the effects assigned rapidly enough to meet
the requirements of the case, on the ground that the tendency to equilib-
1On the influence of carbonic acid in the air upon the temperature of the ground.
Phil. Mag., 1896, pp. 237-276.
2Kosmische Physik, II, p. 503.
3 Ann. Phys. u. Chem., 1898, p. 598.
4 Ibid., 1900, p, 321.
THE PLEISTOCENE OR GLACIAL PERIOD. 445
rium between the carbon dioxide of the air and that of the ocean would
require the whole oceanic content to be reduced proportionally with
the reduction in the atmosphere. But this view seems to neglect
(1) the very slight efficiency of diffusion; (2) the limitation of agita-
tion to a comparatively shallow surface layer; (3) the effects of life
in this surface layer; (4) the interference of uncarbonated waters
arising from ice melting; (5) the long period of circulation necessary
to bring about an interchange between the body of the ocean and
the atmosphere; (6) the part played by temperature in this inter-
change; (7) the part played by ice-formation, and (8) fundamentally,
the change in the basis of equilibrium itself.
II. Variations in supply the working factor. — As already noted, the
foregoing hypothesis makes the depletion of carbon dioxide by chem-
ical union or by oceanic absorption, the working feature, while varia-
tions in the supply are regarded as modifying elements not easily dis-
cussed at present, because the distribution of volcanic action, regarded
as the chief variable, is not well determined. It is possible, how-
ever, to reverse the point of view, and regard the variation in the sup-
ply of carbon dioxide as the working factor and variations in con-
sumption the modifying ones. This latter, if we have not misappre-
hended, is essentially the view of Arrhenius 1 and Hogbom.2
The working application of this form of the hypothesis would be
rather markedly different from that sketched above, but it has not
been worked out into detail, so far as we are aware.
III. Proximate hypotheses. — In the atmospheric class of hypotheses
are to be reckoned two that are proximate but not ultimate hypoth-
eses : namely, the cloud hypothesis,3 and the wind hypothesis.4 Without
doubt clouds and wind are important factors in the development of
glaciation; but if clouds are made the essential factor, the problem
is only shifted to the cause of such persistent clouds covering such
large areas for tens of thousands of years consecutively, with a cool-
ing potency competent to develop the great ice-sheets. The solution
of this seems as formidable as the problem in its usual form. Much
1 Loc. cit.
2 Svensk Kemisk Tedskrift, Bd. VI, 1894.
3Manson, Am. Geol., Vol. XIV, 1894, pp. 192-194; Vol. XXIII, 1899, pp. 44-57,
and Vol. XXIV, 1899, pp. 93-120, 157-180, 205-209.
4Harmer, Geol. Soc. London, 1901; Abstract in Geol. Mag., 1901, p. 327.
446 GEOLOGY.
the same may be said of the suggestion that glaciation was due to a
change in the prevailing direction of the winds. Some notable modi-
fications of the winds must probably be factors in any complete glacial
hypothesis, but the causes and conditions that determined these are
scarcely less problems than glaciation itself. While no theory is ulteri-
orly without dependence on unsolved factors, a theory of a geologic
phenomenon is relatively complete when it is carried back to the gen-
eral course of events that form geologic history, such as deformation,
geographic changes, or astronomic relations.
FORMATIONS OUTSIDE THE ICE-SHEETS.
While the glaciation of middle and high latitudes was the most
striking event of the Quaternary period, by far the larger part of the
earth's surface was not affected directly by the ice. Outside the
area of glaciation, the commoner phases of erosion and deposition were
in progress, and non-glacial Pleistocene formations are wide-spread,
though by no means universal. Degradation in some places was the
antecedent of deposition in others, and under the varied conditions
of the period, various classes of deposits were made, among which
were the following:
(1) Eolian deposits, conspicuous along many sea and lake shores,
along many rivers, and in sundry arid and semi-arid regions, and incon-
spicuous as a dust mantle in every lodgment area, for wind-blown dust
is essentially ubiquitous. (2) Fluwatile deposits were made (a) by
streams which had no direct connection with the ice, and (b) by those
which had such connection. These deposits occur along essentially
all streams of low gradient, and along many streams where the gradient
is not low. Kindred deposits were made by sheet-floods and tem-
porary streams, even far from the courses of permanent streams. They
are common at the bases of most slopes, where they are often more
or less mixed with talus. (3) Lacustrine deposits of both the glacial
and non-glacial types, comparable to the two classes of river deposits,
were formed not only in existing lakes and more or less generally
about their borders, but over the sites of the numerous lakes which
have become extinct since the beginning of the period. (4) Character-
istic deposits were made by springs. (5) Terrestrial organic dep<
(peat, calcareous marl, etc.) abound in many of the ponds and marshes
THE PLEISTOCENE OR GLACIAL PERIOD. 447
to which glaciation gave origin, and also, though less commonly,
outside the area directly affected by the ice. (6) Marine deposits
were made on lands submerged during the Pleistocene period, and
doubtless over essentially all of the ocean bottom. The areas where
such deposits have since emerged are chiefly confined to narrow belts
along the coasts. (7) Volcanic rocks of Pleistocene age are found in
our continent, chiefly west of the Rockies, though volcanic dust is
widely distributed on the Great Plains.
These non-glacial deposits probably appear at the surface over a
larger area than the formations of any earlier period. In the aggre-
gate, they are more extensive and more readily identified than deposits
of like origin referable to any earlier period. If the subaerial deposits
of other periods were equally extensive, they have been largely buried,
destroyed, or so modified as to lose their distinctive characteristics.
The average thickness of the Pleistocene deposits is not great.
Glacial drift and Pleistocene accumulations of debris at the bases of
mountains are sometimes several hundreds of feet thick, and in rare
cases even more ; but otherwise the thickness of non-glacial Pleistocene
deposits rarely exceeds a few score feet.
On the Atlantic and Gulf Coasts.
On the Coastal Plain of the Atlantic and the Gulf of Mexico, there
is a wide-spread but thin body of gravel, sand, loam, and clay, referred
to the Pleistocene period. In altitude it ranges from sea-level up
to several hundred feet, though most of it lies below 200 feet. All of
the non-glacial post-Tertiary deposits of the Atlantic and Gulf plains
were formerly grouped together under the name Columbia.
Soon after the Columbia formation was differentiated1 it was
found to be bipartite, and the terms " High-level Columbia " and
" Low-level Columbia " were applied to the two divisions in the type
area, the District of Columbia.2 Further study has disclosed the
fact that the materials formerly grouped under the one name represent
at least three somewhat distinct stages of deposition.3 Physically
1 McGee, Am. Jour. Sci., Vol. XXXV, 1888, p. 367.
2 McGee, 7th Ann. Kept., U. S. Geol. Surv., 1885-86.
8 Reports of the State Geologist of New Jersey, 1897-1900. The Bridgeton, Pen-
sauken, and Cape May Formations.
448 GEOLOGY.
two of the three divisions do not differ notably from each other, but
their topographic and stratigraphic relations are such as to indicate
that a very considerable interval of erosion elapsed after the deposition
of the first, before the deposition of the second. The third subdi-
vision of the original Columbia formation is much younger than the
others; is, indeed, of last-glacial and post-glacial age.
As originally defined, the Columbia formation was said to have a
fluvial and an extra-fluvial phase. Applied to the Atlantic coastal
plain, this subdivision means that along the valleys leading from the
mountains and the Piedmont plateau to the ocean, the Columbia for-
mation is thicker and composed of coarser and more heterogeneous
materials, than over the inter-stream areas. In the latter position
the formation is composed, in considerable part, of materials derived
from beds close at hand; in the former, it is composed of materials
from all parts of the drainage basin above the point of its occurrence.
In the valleys, the gravel, sand, and loam are more distinctly separated
from one another than in the inter-valley areas, and stratification is
more distinct. To the northward, the heterogeneity of composition
increases as the border of the glacial drift is approached. On the
whole, the formation thickens toward the coast, but is nowhere known
to attain great thickness.
The oldest subdivision of the original Columbia formation is found
at higher levels than the second phase. In the principal valleys it
constitutes broad but often rude terraces, which rise up-stream. Thus
up the Potomac, the Susquehanna, the Delaware, and other valleys,
they rise to altitudes notably above those attained by the extra-
valley phase of the formation.
In the type locality, the Low-level Columbia covers rock terraces
100 feet or so below the high-level phase of the series (Fig. 532). The
relations of the two subdivisions indicate that extensive erosion fol-
lowed the deposition of the high-level Columbia, and that the broad
valleys then developed were subsequently aggraded by sediments simi-
lar to those of the preceding epoch of deposition. The two deposits
are so nearly alike in composition that their separation is based chiefly
on their topographic relations.
In areas of slight relief, the distinction between the high-level
and low-level phases of the Columbia is not always marked topo-
graphically, and the differentiation is then difficult or even impossible.
THE PLEISTOCENE OR GLACIAL PERIOD.
449
1
o>
1
2
^s§
26^
450 GEOLOGY.
Even in such cases, however, there is abundant evidence that the
series is not a unit in origin. Locally at least, deposition probably
alternated repeatedly with erosion, in the course of the history of the
Columbia series. Even where the topographic distinction between
the two most marked divisions of the series is not pronounced, there
is evidence of one interval of erosion more important than others,
and this may well correspond with the time of pronounced erosion
between the high- and low-level members of the series in the type area.
The third phase of the composite Columbia is found at still lower
altitudes, along the streams and coasts. Its disposition is such as
to show that the second phase of the Columbia formation had been
somewhat extensively eroded before the deposition of the third. In
the valleys formed during this interval of erosion, and along the coast
at accordant levels, the third member of the series finds its chief develop-
ment. Its relations, as shown along the valleys, are diagrammatically
represented by Fig. 533. Outside the valleys, the landward edge
of this member of the series is as ill-defined as the landward edge of
the older members in the inter-stream areas. Fig. 534 shows, dia-
grammatically, the supposed relations of the three phases along an
interfluvial tract, from the coast inland. This figure represents the
seaward margin of the oldest subdivision, as buried by the next mem-
ber of the series, and the seaward margin of the latter, as covered, in
turn, by the youngest subdivision. It should be understood that this
relation is diagrammatic, since no section showing the three subdivi-
sions in such superposition has been seen. Since the deposition of
the third phase of the formation but little erosion has taken place.
It should also be understood that the three subdivisions are probably
not sharply separable from one another, because of the manner in which
the deposition took place (see p. 452).
The threefold division of what was originally called the Columbia
formation calls for a change in nomenclature. It is convenient to
have a name for this coastal series as a whole. If the name Columbia
be used in this way, its several subdivisions should have separate names.
In New Jersey, the name Bridgeton has been applied to what is prob-
ably the equivalent of the High-level Columbia, and the name Sunder-
land was later applied to the High-level Columbia of Maryland. The
name Pensauken l has been applied in New Jersey to what is prob-
1 Report of the State Geologist of N. J. for 1894, p. 105.
THE PLEISTOCENE OR GLACIAL PERIOD 451
ably the equivalent of the Low-level Columbia farther south, and this
name may well be given to the second subdivision of the original
Columbia. For this subdivision the name Wicomico has been used in
Maryland. To the youngest phase of the formation the name Cape
May 1 has been applied, from one of its typical localities. In Mary-
land this subdivision has been called the Talbot formation.
Over all the preceding formations, Bridge ton, Pensauken, and
Cape May, and perhaps extending even beyond the oldest and highest
of them, there is a thin and discontinuous deposit of loam, which in
some places seems to represent a phase of deposition distinct from
all the preceding. Similar loam sometimes covers the glacial drift
of last-glacial age. Its interpretation is still an open question.2 It
is very probable that different parts have originated in different ways.
In many places the loam has sufficient thickness to obscure the rela-
tions of the underlying formations.
Stratigraphic relations. — The various members of the Columbia
series rest unconformably on inferior formations. On the Atlantic
Coast, the older divisions often rest on the Lafayette formation, and
often on terranes from which the Lafayette had been eroded before
the deposition of the Columbia series.
Fossils. — The Columbia series rarely contains fossils. At a few
points, however, shells of fresh-water molluscs have been found in
the Pensauken but a few feet above the present sea-level.3 Marine
shells have been found in gravels which are perhaps of Pensauken
age, on the east coast of New Jersey. Such evidence as the few fossils
afford, therefore, is against the marine origin of at least parts of the
formation. The Cape May formation, like the older Pleistocene for-
mations of the Atlantic Coast, is generally without fossils, but marine
shells have been found in it at a few points (southern New Jersey)
a few feet above sea-level,4 and about Philadelphia marine diatoms
have been found in the loam which covers it, up to an altitude of 40 to
60 feet.
1 Report of the State Geologist of N. J. for 1897, p. 20.
2 See Report of State Geologist of N. J. for 1897, p. 20, and Vol. V, Glacial Geology
of N. J.
3 Report of the State Geologist of N. J. for 1896, p. 205.
4 Report of the State Geologist of N. J. for 1885, and Geology of Cape May County
1859.
452 GEOLOGY.
The origin of the Columbia and associated formations. — The origin
of the Columbia formation presents much the same problems as that
of the Lafayette, and is probably to be explained in much the same
way; that is, the series is looked upon as largely fluviatile and sub-
aerial, the result of land aggradation. The occasion for renewed depo-
sition on the Coastal Plain in the Quaternary period probably lay
(1) partly in changes of gradient incident to crustal warpings, and
(2) partly in the climate of the period. Renewed upward bowing
FIG. 535. — Unconformable contact between the Columbia formation and the Potomac,
Washington. D. C. (Darton, U. S. Geol. Surv.)
of the Appalachians and of the plateau to the east of them probably
stimulated the streams descending from them to increased erosion,
and the deposition of a part of their loads on the plain below was a
natural result. Under these circumstances, deposition would prob-
ably have extended up the valleys to altitudes considerably greater
than those of the plain where the principal deposition took place.
The poor assortment of the material, the common cross-bedding, the
numerous trifling unconformities, and the absence of fossils, all are
consistent with this interpretation. So also is another feature of
THE PLEISTOCENE OR GLACIAL PERIOD. 453
the constitution of the material deposited. One of its common con-
stituents is crystalline rock, now generally thoroughly decayed. This
material points to conditions when erosion and transportation exceeded
rock decay, as might be the case after the development of increased
declivity.
The second factor, the climate, contributed to the same end. The
climate of the period was changeable, and at least periodically cold,
as the recurrent ice-sheets show. Under these conditions a larger
proportion than now of the precipitation of the Appalachians was
doubtless in the form of snow, and this was favorable to the flooding
of streams during the melting seasons. At the north, the deposition
of the Columbia material was probably partly by water coming directly
from the ice of the early glacial epochs. Floating ice helped to trans-
port the bowlders of the formation, and so to give it the heterogeneity
which is one of its distinctive features, especially in proximity to the
glacial drift. In this way also, the presence of large bowlders of soft
shale, scores of miles from the nearest outcrop of similar rock, may
be explained.
The cold climate probably affected erosion, and therefore deposi-
tion in another way, for the reduction of temperature was probably
attended by a reduction of vegetation, and any diminution of vegeta-
tion must have reflected itself in .ncreased erosion. The reduction
of vegetation was probably greatest just where erosion was most readily
stimulated, namely in the higher altitudes. The importance of this
consideration has perhaps not been duly recognized.
It is conceived, therefore, that the deposition of the principal sub-
divisions of the Quaternary series of the Coastal Plain resulted from
the combined effect of surface warping and climatic change; that
epochs of notable deposition alternated with epochs when erosion was
dominant in the same regions; and that the materials of each principal
stage of deposition were deposited, shifted, and re-deposited repeatedly,
so that the Bridgeton (High-level Columbia), the Pensauken (Low-
level Columbia), and the Cape May formation, are each really com-
plex series, though they nowhere attain great thickness.
While the Cape May division of the Quaternary was being deposited,
the sea transgressed some parts of the present coast to a slight extent
at the same time that deposition was taking place in the valleys scores
of miles inland, and in some cases hundreds of feet above sea-level.
454 GEOLOGY.
If similar relations existed during the earlier stages of Quaternary
deposition, the seaward edges of the deposits of each principal stage
of deposition may be marine. It is probable also that the series con-
tains estuarine phases of sedimentation, and it can hardly be doubted
that each subdivision now recognized on the land has its equivalent
(in time) marine phase beneath the sea.
The essential contemporaneity of the Cape May formation with
the last glacial epoch, seems to be indicated by the phenomena of the
northern part of the Coastal Plain, and it seems not improbable that
the earlier members of the Quaternary system of the coast were con-
nected with earlier glacial epochs.
In recent times, dunes have been developed at numerous points
along the coast, and their development and destruction is still in
progress.1 Humus deposits also have somewhat extensive develop-
ment in the tidal marshes, and to a less extent elsewhere.
In the Interior.
Some of the non-glacial Pleistocene formations of the interior,
notably the loess, the valley trains, etc., have been referred to in con-
nection with the glacial drift. Apart from such formations, there
are others which seem to be measurably or wholly independent of
the ice.
The wide-spread gravels of the western plains, largely of late Ter-
tiary age, have been referred to, but the deposition of gravels in this
region probably continued into the Pleistocene, is indeed still in progress.
In the general absence of fossils, and with the slight measure of study
which has been devoted to them, Tertiary and Quaternary gravels
have not been sharply differentiated in the interior. The deposits of
this class are largely fluviatile.
In some sandy regions, and along some valleys, there are tracts
and belts of dunes for which the semi-arid conditions are favorable.
Perhaps the most considerable area of dunes is in central Nebraska,
where an area of 24,000 square miles is said to be covered by them.2
1 See for example, the Norfolk, Va.-N. C., folio, U. S. Geol. Surv.
2 Darton, 19th Ann. Rept. U. S. Geol. Surv., Pt. IV; see also topographic maps
of Camp Clarke, Browns Creek, and St. Pauls sheets, and the folios of the state, pub-
lished by the U. S. Geol. Surv.
THE PLEISTOCENE OR GLACIAL PERIOD. 455
Similar areas, though less extensive, occur in Kansas.1 Dunes are
also conspicuous along many valleys in Kansas (see Fig. 2, PL II,
Vol. I) and elsewhere. Small dunes are of common occurrence locally
in the humid region east of the Great Plains. Thus they abound
about the head of Lake Michigan and along its eastern shore, and
along some streams, especially those flowing through sandy tracts.
Even where dunes are wanting, wind-blown sand and dust are wide-
spread, though, excepting the loess, not generally in such quantity
as to be readily recognized. Much of this eolian sand is of very recent
deposition.
Erosion, rather than deposition, was the great feature of the Quater-
nary in the interior, outside the region affected by the ice-sheets; and
in the erosive work, wind, running water, and ground-water have
cooperated.
In the West.
The Quaternary formations of the west belong to all the several
categories mentioned on p. 446, and to this list must be added the glacial
formations, not especially considered in the earlier part of this chapter.
But few of these various sorts of deposits have received close study
over any considerable area, though something is known of all. Among
the deposits which have been most closely studied are those of some
of the numerous lakes which existed at various points west of the
Rockies. Those of the Great Basin are best known (Fig. 536.)
Lacustrine Deposits. Lake Bonneville.2 — The most considerable
of the western Pleistocene lakes was Lake Bonneville, the body of
water of which Great Salt Lake is the diminutive descendant. Its
basin is believed to have been due to crustal deformation, and to have
antedated the lake itself by some considerable period. Previous to
the formation of the lake, the basin is thought to have been arid, a
conclusion based on the great alluvial cones and fans subsequently
covered by the lake. During the pre-lacustrine period of aridity,
such quantities of debris from the surrounding mountains were brought
into the basin as to bury the bases of the mountains to depths of per-
haps 2000 feet, at a maximum.
1 See the Pratt, Syracuse, Lamed, and Kinsley sheets, U. S. Geol. Surv.
2 Gilbert, Mono. I, U. S. Geol. Surv.
B AS IN OF T H E
FIG. 536. — Map showing the position and area of the Quaternary lakes of the Great
Basin. (Gilbert, U. S. Geol. Surv.)
THE PLEISTOCENE OR GLACIAL PERIOD.
457
Following this period of aridity, the climatic conditions were such
that a large lake was brought into existence; but after enduring for a
V :
MAP OF
SHORE TERRACES
PIG. 537 — Contour map of the shore terraces of Lake Bonneville, near Dove Creek,
Utah, with sketch of same below. (Thompson, U. S. Geol. Surv.)
time, it disappeared, apparently by desiccation resulting from change
of climate. Later, the lake was restored, and its water rose some
90 feet higher than before, and found an outlet to the northward.
458 GEOLOGY.
The maximum stand of the water is recorded in various topographic
forms characteristic of shores. The outflow of the lake cut down
the outlet 375 feet, and at this new and lower level, distinct shore
marks were developed. Later, evaporation from the lake again became
more considerable than precipitation and inflow, and the lake gradu-
ally shrank to the present dimensions of Great Salt Lake. At its
maximum, Lake Bonne ville was more than 1000 feet deep, and had an
area of more than 19,000 square miles; the maximum depth of Great
Salt Lake is less than 50 feet (its average less than 20 feet) and its
area but about - that of its ancestor.
FIG. 538.— Ancient deltas of Logan River, at Logan, Utah. (Gilbert, U. S. Geol. Surv.)
As the lake dried up, its waters became separated into numerous
basins, corresponding to the lowest parts of the Bonneville bottom.
Some of these basins, besides that of Great Salt Lake, contain, or have
recently contained, lakes. Others have playas in their lowest parts,
where water gathers after every rain, but does not persist. Great
Salt Lake is apparently doomed to still further decrease by the diver-
sion of water from the feeding streams for purposes of irrigation.
Terraces, deltas, and embankments of other sorts were developed
about the shores of Lake Bonneville wherever the appropriate con-
ditions existed (Figs. 537-539), and the aridity of the climate since
the lake sank below them, has allowed them to remain with little modi-
fication by erosion. As the lake dried up, deposits of salts were made,
among which sodium chloride and sodium sulphate are most abundant.
Gypsum crystals are plentiful, and in places they have been heaped
up into dunes. Great Salt Lake is estimated to contain 400,000,000
tons of common salt, and 30,000,000 tons of sodium sulphate. Both
THE PLEISTOCENE OR GLACIAL PERIOD.
459
are extensively utilized. Calcium carbonate, though not shown in
quantity by analyses of the water, is precipitated in the form of oolite
about the shores of the lake, probably through the influence of organisms.
^x
pfl
MAP OF THE
1) K I. T A S
I.AKK IJOXNF.YILU'
LOGAN K1YK1!
FIG. 539.— Same as Fig. 538, in contours. (Johnson, U. S. Geol. Surv.)
Within the area of Lake Bonneville, igneous eruptions (Fig. 540)
have taken place during the Pleistocene period. These eruptions appear
to have occurred at various stages of the lake's history, and even in post-
460
GEOLOGY.
MAP OF
LAKE BONNEVILLE
showing
FIG. 540. — Map of Lake Bonneville, showing also the areas of basalt (black areas),
some of which are Quaternary, the lines of recent faulting (full black lines), and
the deformation of the basin (dotted lines). The figures on the dotted lines show
the height of the Bonneville shore line above the level of the present Great Salt
Lake. (Gilbert, U. S. Geol. Surv.)
THE PLEISTOCENE OR GLACIAL PERIOD.
461
Bonneville time. Since the Bonneville stage, too, there has been fault-
ing in the basin (Figs. 541-542). At the west base of the Wasatch
FIG. 541. — The trough in the middle foreground was produced by faulting; near
the mouth of Little Cottonwood Canyon, Utah. The trough is in glacial drift.
(Gilbert, U. S. Geol. Surv.)
range, faulting has affected the Bonneville terraces, with displace-
ments of as much as 40 feet. At other points where post-lacustrine
faulting has been observed, the throw is less.
1
FIG. 542. — Fault scarps in the moraine at the mouth of the Little Cottonwood Canyon,
Wasatch Mountains. (Gilbert, U. S. Geol. Surv.)
The diastrophic activities of the region have not been confined
to faulting. The shore lines of the former lake have been deformed
462
GEOLOGY.
FIG. 543. — Gravel embankments along the shore of Lake Lahontan at Buffalo Springs,
Nev. (Russell and Johnson, U. S. Geol. Surv.)
THE PLEISTOCENE OR GLACIAL PERIOD.
463
to the extent of more than 300 feet; that is, some parts of the Bonne-
ville shore line are more than 300 feet higher than others (Fig. 540).
This deformation affects even the later and lower shore lines, and
stands in no intimate relation to the faulting of the region.
Lake Lahontan.1 — Farther west, but still in the area of the Great
Basin, were other lakes, probably contemporaneous with Bonne ville.
The largest was Lake Lahontan, a lake of most irregular outline (Figs. 536
and 547), the history of which was similar to that of Lake Bonneville.
The basin of Lake Lahontan is thought to have been due to the dis-
placement of faulted blocks. As in the case of Bonneville, a condi-
tion of aridity preceded the lake. When increased humidity brought
FIG. 544. — Section of Lahontan sediments, near Agency Bridge, Truckee Canyon
Nev. (Russell, U. S. Geol. Surv.)
the lake into being, its waters rose until they covered an area of nearly
9000 square miles. This stage of the lake, like the first stage of Lake
Bonneville, was followed by a period when the lake nearly or quite
disappeared. Later, it was restored, and its waters rose about 30
feet higher than before, but did not find an outlet. The two stages of
high water in Lake Bonneville and Lahontan have been thought to
correspond with epochs of glaciation in the adjacent mountain regions.
At some stages of the lake's history, the condition of the water
was such as to allow mollusks to live in it, while at other stages it
appears to have been so saline as to have prevented its habitation.
These facts point to considerable fluctuations in the climate during
the history of the lake.
The deposits in Lake Lahontan are comparable to those in Lake
Bonneville (Figs. 543 and 544), but among the clastic sediments are
found thin beds of volcanic ash, and the relative importance of the
chemical precipitates is greater. The main precipitate was calcium
1 Russell, Mono. XI, U. S. Geol. Surv.
464
GEOLOGY.
carbonate, which, in the form of calcareous tufa, was deposited during
at least three distinct stages of the lake's history (Fig. 545). The
FIG. 545. — Tufa deposits in the basin of Lake Lahontan. (Russell, U. S. Geol. Surv.)
oldest tufaceous deposits lined the basin of the lake at the time of its
first expansion; the next were made when the lake was low, between
THE PLEISTOCENE OR GLACIAL PERIOD. 465
the two stages of expansion; and the youngest were made at the time
of the last expansion. Oolite was deposited at some stages of the
lake's history, and is now making about Pyramid Lake. In some parts
of the Lahontan basin there are deposits of salt, and salt is also derived
from brine wells.
Subsequent to the last stage of expansion, the waters appear to
have been completely dried up. The period of maximum desiccation
is thought to have been no more than 300 years ago. Since then the
humidity of the region has so far increased as to develop small lakes
in the deeper parts of the former basin.
All lines of evidence point to the shortness of the time since Lakes
Bonne ville and Lahontan existed. The embankments of sediment
FIG. 546. — Faulting in sediments of Lake Lahontan, Walker River Canyon, Nev.
(Russell, U. S. Geol. Surv.)
about the old borders of the lake seem to be almost as perfect as when
formed, even the valleys which cross the terraces being small. It is
to be remembered, however, that the region is arid and its sediments
porous, conditions which do not favor the ready destruction, or even
the ready disfiguration, of terraces, deltas, etc. Russell infers that
the desiccation of the lake was probably accomplished centuries, but
probably not many thousands of years ago.
Recent as the closing stages of Lake Lahontan's history were,
there have been considerable diastrophic changes in the region since,
for faults affect the lacustrine sediments at various points (Fig. 546).
Some of these faults have been traced more than 100 miles, and the
throw of some of them is not less than 100 feet, though the amount is
usually less. The recent fault movements seem to have been mainly
along the lines of earlier faulting (Fig. 547). It is worthy of note that
the numerous hot springs of the region are mostly along the lines of
recent faulting. This has led to the inference that the friction of
faulting was the source of the heat, but this is clearly not the only
interpretation possible.
FIG. 547. — Map showing the area of Lake Lahontan and the residual lakes of the present
time. The black lines with hachures represent the lines of post-Pleistocene faulting.
Most of them were also lines of pre-Quaternary faulting, and some of the latter,
indicated by black lines, do not represent sites of post-Pleistocene displacement.
The black dots represent springs, many of which are hot. Their proximity to faults
is in some cases striking.
466
THE PLEISTOCENE OR GLACIAL PERIOD. 467
Mono Lake. — A lake which occupied a part of Mono Valley, Cali-
fornia/ had a similar history. The two stages of high water here are
associated with two separate advances of the ice. Glaciers descended
into its basin below the level subsequently reached by the water.
As in the case of the larger lakes farther east, there has been faulting,
deformation of the beach lines, and volcanic action in the basin of
the lake, since the last retreat of the ice. Mono Lake seems to have
been without life throughout most of its history.
There were numerous other Pleistocene lakes in the Basin and moun-
tain regions, but their histories have not been worked out in detail.
Glacial effects. — The extent of glaciation in the western mountains
has been outlined in the early part of this chapter. Throughout the
area glaciated, there is evidence that the erosive work of the ice was
great. This is shown both by the extensive deposits of glacial and
fluvio-glacial origin, and by the forms of the valleys occupied by the
ice. At the east base of the Park Range in Colorado, for example,
there are said to be terminal moraines 1000 feet high.2 In the Uinta
Mountains, the terminal moraines are much less massive, but lateral
moraines 1000 feet high 3 are found. Under the conditions of active
drainage which existed in the mountains, much of the glacial debris
was carried beyond the ice by the water emanating from it, and deposited
in the valleys and " parks/' or on the plains below. Nowhere in the
world where accurate topographic maps have been made, are glacial
cirques, the result of a peculiar phase of glacier erosion, better developed
than in these mountains.4
The characteristics of the mountain valleys which were occupied
by considerable glaciers, are essentially constant. They include (1) well
developed cirques at the heads (Fig. 548 and PL XIX, Vol. I); (2) the
upper parts of the valleys, often for some distance below the cirques,
are so thoroughly cleaned out, that little loose debris, except that
due to post-glacial weathering, remains; (3) numerous tributary
valleys are hanging (Fig. 262, p. 290, Vol. I), and their waters form
cataracts (Fig. 263, p. 291, Vol. I); (4) at and near the limits of the
1 The Pleistocene History of Mono Valley, Russell, 8th Ann. Rept. U. S. Geol. Surv.
2 King, op. cit., p. 468.
3 This means that the drift is .1000 feet deep. The crests of the lateral moraines
are locally 2500 feet above the valley bottoms.
4 See Hayden Peak and Gilbert Peak, Utah, topographic sheets of the U. S. GeoL
Surv., for fine examples of large cirques.
468 GEOLOGY.
ice, at any stage when its end or edges remained nearly constant in
position for a time, there are heavy accumulations of drift, lateral
moraines often being more conspicuous than- terminal; (5) the valleys
%n^> ,. • . . • '"isP^// '
^v T? T^ ^ • T*
Y o ^ ! 5 '
Tokewanna
Pk
V/XIh I X T
RE S E R V A T I 0 NV
\
FIG. 548. — Glacial cirques in the Uinta Mountains. (Hayden Peak quadrangle,
U. S. Geol. Surv.)
contain lakes (PI. XIX, Vol. I), some of which occupy rock basins
in the cirques, and some occupy basins produced by drift dams in
the valleys below the cirques; and (6) valley trains or outwash plains
LO
THE PLEISTOCENE OR GLACIAL PERIOD.
469
below the moraines. The partial removal of these deposits has
developed terraces (Fig» 551).
FIG. 549. — Lateral moraine in the valley of the North Fork of Clear Creek, Bighorn
Mountains, Wyo. (Blackwelder.) (See also Fig. 278, Vol. I.)
Glacial lake deposits. — By obstructing valleys, the mountain glaciers
of the west gave rise to numerous temporary lakes in which extensive
FIG. 550. — The moraines about the lower end of a mountain valley.
Bloody Canyon, Cal.
beds of lacustrine sediments were laid down, The extent of such
lakes in the west and northwest has not been determined, but where
470
GEOLOGY.
FIG. 551. — Terraces of the Columbia, near Chelan, Wash.
gravels. (At wood.)
The terraces are of glacial
FIG. 552. — Glacial lakes in the upper end of a glacial valley (cirque) ; near the head
of Commodore Gulch. Silverton, Colo., quadrangle. (R. T. Chamberlin.)
THE PLEISTOCENE OR GLACIAL PERIOD.
471
glaciation was extensive, derangement of the drainage was common,
and deposits of glacio-lacustrine clay, hundreds of feet deep, are known
at some points. Where such deposits were made in narrow valleys
now drained, they have been partly removed, and their remnants con-
stitute terraces.
Topographic unconformity.1 — Glaciation in the west was also respon-
sible for a phase of topography worthy of special mention. It is illus-
trated by Fig. 553. A great glacier passed down through the valley, oblit-
erating the erosion topography of its lower slopes, partly by wearing
away the ends of the ridges between the tributary valleys, and partly
by filling the lower ends of those valleys, up to the limit of the ice.
FIG. 553. — Topographic unconformity developed by glaciation, and by a glacial
lake. Lower end of Lake Chelan, Wash. (Atwood.)
The result was that the well-developed drainage lines on the upper
slopes were effaced below, and post-glacial erosion has since developed
new channels in this part, continuous with the older ones above, thus
giving rise to a topographic unconformity. In the case shown in
Fig. 553 the lake (Chelan) stood at the levels of the terraces after
the ice disappeared, and its shore deposits helped to destroy the lower
ends of the preglacial drainage lines. Fig. 551 also shows topographic
unconformity.
All evidences point to the conclusion that the glaciation, or at
least the latest glaciation, of the western mountains was of very recent
date. From a general study of the data at hand, it would appear
1 Jour, of Geol., Vol. XII, p. 707.
472 GEOLOGY.
that the last glaciation of the west can hardly have preceded the Wis-
consin glacial epoch of the interior. Nevertheless there has been
much post-glacial weathering, especially that resulting from the expan-
sion and contraction due to changes in temperature. In favorable
localities, this has resulted in the development of enormous bodies
of talus, some of which are said to be 1000 feet in thickness.1 Such
accumulations are most extensive in the Sierras.
Alluvial and talus deposits. — In the basin region of Utah and Nevada,
there are exceptional deposits of detritus, the accumulation of which
was favored by the geographic and climatic conditions. The mountain
ranges of the basin region are separated by broad valleys. From the
steep slopes, detritus is carried down both by descending torrents
and by gravity, and while it is largely deposited at and against the
bases of the mountains, some of it is spread widely over the surround-
ing plains. This debris is mainly unstratified, or poorly stratified,
and some of it is very coarse. It occurs in greatest quantity where
canyons issue from the mountains, and in such situations huge fans
of bowlders, sometimes 1000 feet in height, are found.2 The torrents
were able to carry this coarse material so long as they were confined
within the canyons, but with the change of gradient below, the water
gave up its load. Where the adjacent mountains are of limestone,
the detritus against their bases is often firmly cemented into breccia
by lime carbonate. The geographic conditions in the basin region
are such as to cause most of the coarser products of erosion from the
mountain to be deposited on the lowlands about them. If the Quater-
nary talus and alluvial deposits were sharply separable from those
of late Tertiary age, they would afford a rough measure of the Quater-
nary erosion in the mountains.
As the glacial deposits increase in importance to the north, talus
and other subaerial accumulations become less conspicuous, and are
of much less importance in Montana, Idaho; and Washington, than
in the more arid regions farther south.
Talus accumulations take on various forms, as shown in Figs. 554
to 556. Fig. 554 shows talus in its normal form. Fig. 555 shows a
type of accumulation not uncommon in the western mountains. In
some cases at least this disposition of the talus appears to be due to
1 King, op. cit., p. 472. 2 King, op. cit.
THE PLEISTOCENE OR GLACIAL PERIOD.
473
FIG. 554. — Normal steep talus slope.
FIG. 555. — Shows the effects of snow-banks at the bases of slopes, on the disposition
of talus. White Rocks Creek, Uinta Mountains, Utah. (Church.)
474 GEOLOGY.
snow banks at the bases of the mountains. The descending talus
rolls out over the snow, lodging at its outer edge. It is possible that
in some of these cases there is incipient slumping of the talus itself.
Fig. 556 shows another type of talus accumulation common in some
of the higher mountains of the west. In some cases these bodies of
talus have the general outline of a glacier, and have therefore been
called " talus glaciers." Their development probably involves several
PIG. 556. — An accumulation of talus, where slumping, etc., have been operative.
Near Silverton, Colo., at head of Horseshoe basin. (Cross, U. S. Geol. Surv.)
processes besides the descent of loose material down steep slopes.
These processes probably include (1) the passage of the talus over
snow-banks at the bases of cliffs, (2) sliding, creeping, and slumping
of bodies of talus, perhaps both when bound together by ice and
when not so cemented, and (3) incipient glacial motion.
All such accumulations now conspicuous in the western mountains are
largely or wholly post-glacial, and their development is still in progress.
Eolian deposits. — One of the agencies concerned, both with erosion
and deposition, in the western region, is the wind. Its erosive work
is shown in the peculiar carving which affects the cliffs and projec-
THE PLEISTOCENE OR GLACIAL PERIOD. 475
tions of rock at many points (Fig. 557), and its depositional work
by the dunes, which are not rare. The erosive work of the wind is
of far greater importance than is commonly appreciated by those
unfamiliar with arid regions. Loess apparently of eolian origin, some-
times with volcanic dust interstratified, is wide-spread in some parts
of eastern Washington and northeastern Oregon.1
FIG. 557. — Illustrating wind-carving. Palmetto Mountains, Cal.
(Turner, U. S. Geol. Surv.)
Deposition from solution. — About many springs, as in the Yellow-
stone Park, deposits of siliceous sinter and calcareous tufa are now
making (Figs. 214-218, Vol. I), and more considerable deposits of the
latter material antedate the present by some considerable interval
of time. Many of these deposits probably fall within the limits of
the Pleistocene period. Their distribution seems to indicate that the
sites of deposition have become successively lower and lower, as the
valleys have been deepened, the springs taking advantage of suc-
cessively lower avenues of escape. Tufaceous deposits of the same
type are known at various other points in the western mountains.
1 Salisbury, Jour, of Geol., Vol. IX, p. 730.
476
GEOLOGY.
Marine deposits. — Along the western coast of the United States
there are marine deposits reaching inland some distance from the
FIG. 558. — A sink-hole of recent development near Meade, Kan.
(Johnson, U. S. Geol. Surv.)
coast. They are known to extend up to altitudes of 200 or 300 feet
in California 1 and Oregon, and perhaps even higher. The Pleistocene
submergence indicated by the disposition of these beds must have
•' >-'u» - '• " «•'•• • -• '»•'" •'"' •Tt Vii,^erIL";'?Ti" -ei»oC«ne But
FIG. 559. — An unconformity between Pleistocene formations on the coast of Cali-
fornia near Santa Barbara. (Messrs. Arnold.)
given origin to considerable bays in the lower courses of the Columbia
and Willamette valleys. In southern California there are two marine
Pleistocene formations separated by an unconformity2 (Fig. 559).
1 Ashley, Jour, of Geol., Vol. Ill, pp. 446-50.
2 The Messrs. Arnold, Jour, of Geol., Vol. X, pp. 117-135.
THE PLEISTOCENE OR GLACIAL PERIOD.
477
By far the larger part of the marine Quaternary deposits of the coasts
of the continent are still beneath the sea. As interpreted by the
marine fossils, the climate of that portion of the Pleistocene in southern
California which is represented by these marine stages, was distinctly
warmer than that of the Pliocene; 1 but this does not apply, probably,
to any large part of either period.
Igneous rocks. — The late Tertiary eruptions of North America
have not everywhere been clearly separated from those of the Quater-
FIG. 560. — A floated crag of scoria, in recent lava-flows, Cinder Buttes, Ida.
(Russell, U. S. Geol. Surv.)
nary period, but there are in numerous places igneous rocks which are
clearly post-Tertiary, some of them even late Quaternary. Some of
these very young igneous rocks have been referred to in connection
with the history of Lakes Bonneville, Lahontan, and Mono, but they
are by no means confined to the basins of these lakes. Mount Shasta
shows several post-glacial lava-flows,2 and there are small cinder
cones on alluvial cones at the east base of the Sierras in southeastern
California.
1 Fairbanks, Jour, of Geol., Vol. VI, p. 566.
2Diller, Physiography of the United States, pp. 245 et seq.
478
GEOLOGY.
In other localities, the reference of lavas, tuffs, etc., to this period
depends on different criteria. In southern California (Mohave desert)
FIG. 561. — Oven of clots of plastic lava. Jordan Craters, Ore.
(Russell, U. S. Geol. Surv.)
and northern Arizona (vicinity of Flagstaff), for example, there are
cinder cones and lava-flows of limited extent which are so slightly
FIG. 562. — Pressure ridge developed in fresh lavas. Jordan Craters, Ore.
(Russell, U. S. Geol. Surv.)
touched by erosion that there can be little doubt that they date from
a time long subsequent to the beginning of the Quaternary period.
THE PLEISTOCENE OR GLACIAL PERIOD.
479
Judged by the same criteria, there are lava-flows and cinder cones of
Quaternary age in New Mexico (Fig. 563), * Colorado, Utah, Nevada,
Oregon (Figs. 561 and 562), Idaho (Fig. 560),2 Washington,3 and at
various points in the Sierras.4 On many of them vegetation has hardly
begun to gain a foothold. Gilbert estimates that of 250 lava fields
observed in these states, 15% are of Pleistocene age, and of 350 vol-
canic cones in the same states, 60% are considered to be Pleistocene.5
Volcanic ash is interbedded with loess at various points in eastern
FIG. 563. — Edge of " malpais " (lava), Tularosa Desert, White Oak, N. M.
(Hill, U. S. Geol. Surv.)
Washington and Oregon,6 and overlies glacial moraines in some parts
of Alaska. Glacier Peak, Washington, is the remnant of a volcano
formed after the base-leveling (Pliocene) of the Cascade Mountain
region, and probably after the elevation of the base-leveled tract.7
Mount Rainier dates from about the same time.
1 Tarr, Am. Nat., Vol. 25, pp. 524-527, 1891.
2Nampa, Ida., folio, U. S. Geol. Surv.; also Russell, Bull. 217, U. S. Geol. Surv.
3Tacoma and Ellensburg, Wash., folios, U. S. Geol. Surv.
4 See Bidwell Bar, Colfax, Downieville, Lassen Peak, Pyramid Peak, and Truckee,
Cal., folios, U. S. Geol. Surv.
6 Mono. I, U. S. Geol. Surv., pp. 323-337.
"Jour, of Geol., Vol. IX, p. 730.
'Russell, 20th Ann. Rept. U. S. Geol. Surv., Pt. II, p. 134.
480 GEOLOGY.
Igneous rock has occasionally had a significant influence on modern
vegetation, without regard to the age of the lava itself. The unwooded
tract shown in Fig. 564 corresponds somewhat accurately with a dike
FIG. 564. — A basic dike, cutting crystalline schists, is the cause of the absence of
trees in the central part of the area shown. Bighorn Mountains, southwest of
Buffalo, Wyo. (Kiimmel.)
of basic rock which affects the crystalline schists of the Bighorn Moun-
tains.
~~~~~\
CHANGES OF LEVEL DURING THE PLEISTOCENE.
The very considerable changes of level which marked the closing
stages of the Pliocene have been mentioned, and many of them doubt-
less continued into the Pleistocene.
Certain minor warpings of later date, such as those which affected
the basins of Lakes Bonneville and Lahontan during the Pleistocene
have also been noted, but such changes are probably but a meager
index of the crustal wrarpings of the period. Specific data on this
point are less abundant than could be desired, for the phenomena of
erosion and deposition which followed the elevation of the Ozarkian
or Sierran epoch are not readily differentiated from the similar phe-
nomena resulting from later elevation. Nevertheless evidence of Pleis-
tocene changes of level, as distinct from late Pliocene, are not wanting,
especially near the coasts and about the shores of the Great Lakes.
From the evidence at hand, it appears that deformative movements were
wide-spread both in the western mountains and in the area covered by
THE PLEISTOCENE OR GLACIAL PERIOD. 481
the great ice-sheets. There have also been changes of level, though
probably less extensive, in the non-glaciated areas of the southern
and southeastern part of the continent.
As already noted, some of the islands of southern California 1 seem
to have risen something like 1500 feet since the Pliocene. Other parts
of the California coast, and some of the adjacent islands, have been
subsiding during the same period.2 Near San Francisco, the surface
is thought to have ranged from 1800 feet below its present level, to
400 feet above.3 Walcott has estimated that there has been eleva-
tion in the Inyo Mountains of California to the extent of 3000 feet
during the Pleistocene.4 Along the northwestern coast of Oregon, it
has been estimated that there has been a rise of at least 200 feet
during the Pleistocene.5 Data concerning Pleistocene changes of level
in the west are not sufficiently numerous to permit the determination
of the axes of movement, if such there be.
In general, the areas covered by the ice of the glacial period have
risen since the ice melted. It is a tenable hypothesis that the rise,
or some part of it, has resulted from the melting of the ice, and that
it followed a depression occasioned by the weight of the ice. The
rise of the land has, in general terms, been greatest where the ice was
thickest.6 This rise of the glacial centers is shown in many ways, but
especially by the raised beaches along the coast lines, and by the deformed
shore lines of the interior lakes. Thus the shore lines of Lake Agassiz 7
are no longer horizontal, but are considerably higher^at the north than
at the south. Their inclination is as much as a foot to the mile in
the northern part of the basin. At the National Boundary, the shore
lines are 175 feet above those at the southern terminus of the lake,
and 200 miles north of the boundary they are 400 feet above the same
point. This deformation was largely accomplished before the lake
disappeared.
1 W. S. T. Smith, Bull. Dept. of Geol., Univ. of Cal., Vol. II. Reviewed in Jour.
of Geol., Vol. VIII, p. 780.
2 Lawson, Bull. Dept. Geol., Univ. of Cal., Vol. I. Reviewed in Jour. Geol., Vol. II,
p. 235.
3 Ashley, Jour, of Geol., Vol. Ill, p. 449.
4 Jour, of Geol., Vol. V, p. 340.
6 Diller, 17th Ann. Rept. U. S. Geol. Surv., Ft. I.
c DeGeer, Proc. Boston Soc. Nat. Hist., Vol. XXV, 1892.
7 Upham, Mono. XXV, U. S. Geol. Surv.
482 GEOLOGY:
The shore lines of the Great Lakes have been similarly warped. Thus
the shore lines of Lake Iroquois,1 the ancestor of Lake Ontario, decline
from the northeast to the southwest at the average rate of three and
a half feet per mile, the slope being steeper to the north and gentler
to the south. The old shore lines east of the east end of Lake Ontario,
are about 400 feet higher than those at the southwest end. The beaches
of Lake Algonquin2 (Fig. 521) are 25 feet above the present lake
at Port Huron, and 635 feet above the lake at North Bay, Ontario.
The shore lines of the Michigan lobe of Lake Algonquin are 205 feet,
above the lake at Mackinac, and are estimated to be 100 feet below
the lake at Chicago. Similar figures might be cited for other localities.
The shores of the Nipissing lakes (Fig. 522) show a similar
though lesser, deformation. Since the Nipissing lakes were later
than the preceding, their shore lines show that the deformation was
in progress while the ice was retreating.3 The import of all these
data is the same, namely, that the land or the water surface has been
warped since the ice melted, and the change has been greatest toward
the centers of glaciation, and that it began before the lakes had attained
their present dimensions. A part of the change is undoubtedly due
to the effect of the attraction of the ice on the water.4 This, how*
ever, leaves a large residuum to be otherwise explained. The history
of many small lakes affords data of the same sort.5
Along the Atlantic coast south of the area of glaciation there have
perhaps been complex movements, but of no great range, in the Pleis-
tocene period. On the whole, elevation (relative) appears to have
exceeded the depression, but the latest movement (present) appears
to have been one of depression, as the drowned ends of the valleys
between Long Island and Carolina, and numerous other minor
1 Gilbert, 18th Ann. Kept., U. S. Geol. Surv.
2 Taylor, A Short History of the Great Lakes, published in " Studies in Indiana
Geography "; also Am. Jour. Sci., Vol. LXIX (1895), pp. 69, 249.
3 Other references relating to post-glacial deformation are the following : Spencer,
J. W., Am. Jour. Sci., Vol. XL (1890), p. 443; Vol. XLI (1891X p. 12; Vol. XLII
(1891), p. 201; DeGeer, Proc. Bos. Soc. Nat. Hist., Vol. XXV (1892); Upham, Jour.
G., Vol. II (1894), p. 383; Taylor, Am. Geol., Vol. XIII (1894), pp. 316 and 365;
Am. Jour. Sci., Vol. XLIX (1895), pp. 69, 249; Bull. Am. Jour. Sci., ser. 4, Vol. I,
pp. 219, 228, 1896; Coleman, Bull. Geol. Soc. Am., Vol. X (1898), p. 165 et seq.;
Fairchild, Bull. Geol. Soc. Am., Vol. X (1898), p. 27 et seq.
4 Woodward, Bull. 48, U. S. Geol. Surv.
5 Lake Passaic, Geol. Surv. of N. J., 1893.
THE PLEISTOCENE OR GLACIAL PERIOD. 483
phenomena, such as submerged peat bogs, meadows, forests, etc.,
show.
It is not improbable that movements of equal magnitude have
affected the interior regions of the continent, but except about the
lakes, there is no datum plane like the sea-level to which these changes
may be readily referred. In a few places, notable local deformation
is known. In western New York l and Ohio, the solution of under-
lying gypsum and salt is suspected of being the occasion of some of
the slight deformations which have been observed.
FOREIGN.
The salient points in the glacial history of Europe have already
been sketched and some indication has been given of the extent of
the deployment of ice in other continents. It need only be added
here that outside the areas affected by the ice, there are, in all con-
tinents, subaerial accumulations of talus, wash, and creep at the bases
of mountains, deposits of alluvium in the valleys, and eolian deposits.
About the coasts at many points on various continents there are marine
sediments ranging from a few feet to hundreds of feet above sea-level.
In Europe there are cave deposits regarded as Pleistocene, which are
of especial interest because they contain human relics, probably the
oldest known. The relics consist of rude stone implements, bones of
mammals with human markings on them, and bones of human beings.
THE LIFE OF THE PLEISTOCENE PERIOD.
Destructive effects of glaciation. — Just as the great ice deploy-
ment was the supreme physical event of the Pleistocene period, so
the effect of glaciation on the life of the times was the foremost sub-
ject of biological importance. It is altogether reasonable to assume
that the burial of several million square miles beneath successive mantles
of ice, abetted by the southward extension of attendant cold zones and
cold currents, wrought great destruction of life, and forced upon what
survived no little modification. The logic is so cogent that we must
believe it to be true; but several embarrassments attend an attempt
to statistically demonstrate the conclusion, and to interpret its pre-
cise nature. For concrete proof of the effects, we naturally resort to-
1 Gilbert, Proc. Am. Ass. Adv. of Sci., Vol. XL, p. 249.
484 GEOLOGY.
a comparison between the pre-glacial life-record and the post-glacial.
But the pre-glacial record is wholly a fossil one, subject to the well-
known defects of such a record, and subject also to the special forms
of destruction that attended the ice invasions. The existing record,
on the other hand, is one of immediate and unobstructed observation,
and is therefore immeasurably more complete. It follows that many
pre-glacial species are found in this very full record that would not
appear in a fossil record comparable with that of the pre-glacial time,
and hence the number of apparent extinctions of Pliocene species is
very much less than would appear if the comparison were made with
a post-glacial fossil record — such a record of present life, for example,
as would be found by geologists some millions of years hence, if it
had in the meanwhile been subjected to the usual geological agencies
of burial and destruction. Without doubt, multitudes of pre-glacial
species yet live that are imminently moribund, and many of these
would not be found in a fossil list of the distant future, under usual
geologic conditions. It is very difficult to make adequate allowances
for this inequality in the records when comparing pre-glacial and post-
glacial life, and hence it is difficult to measure, by such a comparison,
the destructive effects of the intervening ice invasion.
It is to be noted further that the resilience of life is very rapid,
when measured in geologic terms. The excessive possibilities of mul-
tiplication of most living creatures give great capacity for recovery
from depletions, and as our present census is taken some thousands
of years at least after the last notable ice invasion, there has been,
without question, great increase of life, especially in the higher lati-
tudes most affected by the glaciation.
An added source of embarrassment in the comparison is the espe-
cially disturbing influence of man. This is indeed to be regarded as
a geological influence, and to be put in the same category as the influ-
ence of other races, as they have risen to dominance; but none the
less it qualifies the comparison of life before and after the glacial period,
so far as it concerns the destructive effects of the ice invasions.
Of the marine Pliocene invertebrates, more than half the known
species are now living, whereas, in the transition between several of
the more ancient periods, nearly all species disappeared. Of the Plio-
cene plant species, a very considerable percentage are still living. On
the other hand, the land vertebrates were very generally replaced by
THE PLEISTOCENE OR GLACIAL PERIOD. 485
new species or became extinct. The same appears to have been true
of the insects. Interpreted in the light of the above considerations,
there seems warrant for the view that the ice invasions wrought a
very serious depression in the life of the globe. It is scarcely possible
to avoid the conviction that, at the height of glaciation, the sum total
of life on the globe was very greatly reduced. It is probable that
even the re-expanded life of to-day is appreciably inferior in abundance
to that of the middle Tertiary. Our era is probably one of relative
impoverishment, and what is perhaps more important, it is probably
a period of relatively poor adjustment of life to life, and of life to phys-
ical environment. It is improbable that, in the process of recovery
of the millions of square miles denuded of life by the ice-sheets, there
has yet been worked out the best balance between the vegetative life
and the soils and climatic conditions on which it is dependent, between
the herbivorous animals and the plants on which they are dependent,
and between the carnivorous animals and the herbivores on which
they prey, together with all the complicated sub- adjustments that
are involved in a well-adjusted peopling of the earth.
To-and-fro migration. — A distinguishing feature of the effects of
the ice invasions on the life of the glacial period in northern latitudes
was an enforced oscillatory migration in latitude. With every advance
of the ice, the whole fauna and flora of the affected region was forced
to migrate in front of it, or suffer extinction. The arctic species imme-
diately adjacent to the ice border crowded upon the sub-arctic forms
next south of them, the sub-arctic forms crowded upon the cold-tem-
perate forms, and these in turn upon the warm-temperate types, and
so on. It is not unlikely that the limits of the tropical zones even
were shifted, and the torrid belt appreciably constricted. With the
succeeding deglaciation of the interglacial stages, a reversed migration
followed. Present evidence seems to warrant the belief that five or
six such to-and-fro migrations were experienced in America and Europe,
and that the southward and northward swing of these movements
was several hundred miles in extent, in some cases perhaps one to
two thousand miles. Some of the interglacial epochs saw a northward
extension of mild-temperate forms greater than that of to-day, from which
it is inferred that the interglacial climates were milder than the present,
and hence that the ice-sheets wrere at least as much reduced as now.
There is in this also ground for the inference that the northern tracts
486 GEOLOGY.
were at least as extensively peopled by plants and animals as they
are to-day. This carries the conclusion that the migratory swing in
these more pronounced cases was at least 2000 miles in North America,
and more than 1000 miles in Europe. As indicated in the physical
description, the geological evidences drawn from erosion, weathering,
and organic accumulation warrant the belief that the interglacial
intervals were long enough to permit a complete northern return,
and the fossil evidence supports the conclusion that the climates were
congenial enough to invite it.
The forced migrations must, in their nature, have been peculiarly
effective in bringing to bear a severe struggle for existence, and in call-
ing into play the full resources of the plastic adaptation of the life.
Forms previously specialized to meet local conditions were put to a
most adverse test, for the invading ice forced every form within the
glaciated area to move on, while the fringing zones of depressed tem-
perature encircling each ice-sheet, forced plant and animal life, even
beyond the ice border, to seek new fields and new relations, both phys-
ical and organic. An incidental result of this wholesale migration
was an unwonted commingling of plants and animals, for every aggres-
sive form pushed forward in the van of the advancing zone, and hence
came into new organic environment, while every laggard form fell
behind, and was overtaken by the less reluctant migrants.
Definite climatic zones. — From the nature of the case, and from
the evidence, it appears that not only must sharply defined climatic
zones have surrounded the invading ice-sheets, but that these must
have been much more strongly distinguished from one another in
temperature than had previously been the case since the Permian times.
As these diverse zones were alternately pushed forward and withdrawn
by the advances and retreats of the ice, every organism was forced
by a special stress, either to adapt itself to a new zone, to migrate,
or to suffer extinction.
Climatic adaptations. — Two or three notable results appear to
have followed. Certain forms became more highly adapted to special
climatic zones than they had been previously. It has been remarked
before that the floras of the middle Tertiary were highly mixed, judged
by the present climatic adaptations of the species. Types which we
now regard as tropical were living in high latitudes, commingled with
forms which are now boreal. So also forms that are now boreal were
THE PLEISTOCENE OR GLACIAL PERIOD. 487
then living in low latitudes, with forms now tropical. The sifting influ-
ences of the to-and-fro movement of the sharply differentiated climatic
zones, seem to have sorted out the mixed assemblage, or to have forced
them into special adaptations, or both, so that to-day most species are
confined to definite climatic zones. This was not universal, however.
Certain forms seem to have met the stress of the times by becoming
adapted to various climatic conditions. This versatility of adaptation
finds its highest expression in man, but in this case it is secured by
extraneous means not available to the lower creatures. Seasonal
oscillations are met by birds and certain other animals by seasonal
migration. The cases of versatile adaptation are, however, quite
inferior in number to those adapted to limited climatic zones only.
Superposition of cold and warm faunas and floras in the record. —
The to-and-fro movement of the faunas and floras introduced into the
record exceptional superpositions of faunas upon one another. The
succession was orderly but unusual. Where a complete record could
be made, as in a depositing tract just outside the limit of the invading
ice, the full series for the advancing stages of an ice invasion should
embrace a succession of faunas and floras ranging from the temperate,
through cold-temperate and sub-arctic, to the extreme arctic types,
while a full record of the retreating stages of the ice should embrace
the same series reversed. Such an orderly superposition should ideally
be repeated as often as there were ice invasions of the requisite mag-
nitude. In every interglacial period, therefore, there should be embraced
ideally a series of forms ranging from the arctic to the most tem-
perate compatible with the interglacial conditions, and thence back-
ward to the arctic. It is important to observe this range in interpreting
the fossils of interglacial deposits, for the presence of arctic and sub-
arctic faunas and floras in the lowermost and uppermost portions of
an interglacial series does not necessarily preclude the occurrence of
temperate forms in its middle part. Care in observing the exact hori-
zons from which fossils come is obviously required to avoid mingling;
distinct groups. It is obvious so delicate and so changeable a record
would only be perfectly preserved under exceptionally favorable con-
ditions. No series having such ideal completeness has yet been described,
but series embracing sufficient representatives of cold and warm
climates are known to justify this ideal conception, and to make it
the working basis of observation, record, and interpretation.
488 GEOLOGY.
Mixing of relics. — Not only was such an ideal symmetry in the suc-
cession of faunas and floras too delicate to be often perfectly preserved,
but it was easily subject to mutilation and mixture. Relics which
were deposited in the first stages of retreat were liable to be washed
out by the succeeding drainage and commingled with the deposits
of a later stage. So also, as these interglacial beds were loose deposits
and more or less exposed at the surface, they were subject, at vari-
ous later times, to various kinds of disturbance, as by the burrowing
of animals, the overturning of trees, the filling of root-holes, and the
various incidental disturbances which affect loose superficial deposits.
There were also normal shiftings of fluvial material, the reworking
of river-bottoms and terraces, the cutting and filling of gullies, the
creeping and sliding on declivities, the inevitable slope-wash, and simi-
lar surface disturbances. Unusual circumspection is therefore requisite
in observing and interpreting the life relics found in this class of deposits.
Real intermingling of northern and southern species. — Besides the
post-depositional mixing of forms that were originally separate, there
was undoubtedly a true intermingling of northern and southern species
while living, for the migrations could not well keep even pace with
the climatic variations. Plants necessarily lingered until the invading
climate destroyed them. The species migrated by the accidental
transportation of their seeds, but the individual plants had no such
power of migration, and they, and the offspring of such seed as they
planted beneath and about them, remained until destroyed. Under
these conditions, the advance forms of each shifting zone must inevi-
tably have overtaken and mingled with the lingering forms of the
adjacent zone, and these must have been subject to burial and fossiliza-
tion together. This also serves to perplex interpretation.
Even in the case of animal species whose facilities for migration
are freer, the literature of the subject contains puzzling statements
of strange associations. In the caves of Britain, the relics of the arctic
musk-ox are said to be found closely associated with those of the hippo-
potamus; in the caves of France, the relics of the reindeer with those
of the lion; in the caves of Belgium, the auroch and the Alpine chamois
with the sub -tropical hyena.
Cave deposits. — A special phase of record, and also of the mixing
of relics, is found in the cave deposits of the period. Caves were un-
doubtedly the resorts of land animals in the Tertiary and earlier periods,
THE PLEISTOCENE OR GLACIAL PERIOD. 489
but as caves are rather transient features, subject to early oblitera-
tion, they and their contents are rarely preserved in the record of the
more ancient periods. Those which were formed so late as the Pleis-
tocene period, however, have frequently endured, and have become
the receptacles of valuable relics. The cave earth and the stalag-
mite that accumulated on the bottoms of the caves enveloped and
retained animal relics more often than most superficial deposits, for
the obvious reason that the caves were not only frequented by many
predaceous animals, but were the depository of the inedible relics of
the prey these animals dragged into their retreats. So long as the
bottoms of the caves were occupied by cave earth only, this was liable
to be dug over by the fossorial forms of the cave-frequenting animals,
and the relics of different stages mixed. When, however, the earth
was periodically covered by a floor of stalagmite, mixture was restricted
to the intervening stages, and the inter-stalagmite relics recorded the
order of occupancy with measurable fidelity. Cave deposits are chiefly
limited to non-glacial regions, and to those glaciated regions where
erosion did not cut them away or the deep drift bury them beyond
reach. Fissures, as well as sinks and caverns, occasionally preserved
the relics of animals that fell or were washed into them from above.
In these cases, the order of burial is usually subject to some doubt
owing to irregularities in the mode of filling; but in some cases the
succession is fairly certain. In such cases, however, the known order
of the life succession is usually more depended upon to determine the
age of the several portions of the deposits, than is the order of the
deposits to fix the age of the life.
Existing alpine remnants of the migrations. — Significant evidence
of the northerly and southerly migrations of the glacial period is
found recorded in the present life of the higher mountains within
or near the borders of the once glaciated areas. It is obvious that
at the time the ice stood in the vicinity of these mountains, the only
life which could occupy them, if any at all, was of the arctic type.
As the ice retired to the north, the arctic life of the surrounding low-
lands moved northward after it, and the temperate life came on to
take its place. Upon the mountain sides and summits, however, the
arctic life still found congenial conditions; but it was compelled to
ascend to higher and higher altitudes as the warmer climates advanced.
It was thus soon cut off from the retreating arctic life of the lowlands,
490 GEOLOGY.
and became at length thoroughly isolated on the upper zones of the
mountains. On the summits of the higher peaks, such life still finds
suitable conditions, and stands as a living record of the former life
of the zone bordering the ice-sheet and surrounding the mountain
base. On the heights of some of the Appalachians, of Mount Washing-
ton, and of similar peaks, arctic plants, insects, and small mammals,
whose kin now live in the arctic zone, remain to this day.
Life of the Interglacial Stages.
For obvious reasons very little is known of the life of the glacial
stages themselves, except as it is inferred from fossils found in regions
outside the territory invaded by the ice. The precise succession in
these regions, in America at least, has not yet been so closely correlated
with the several glacial stages as to make conclusions wholly safe.
The general relations of life to the adjacent ice invasions are deter-
minable; but as yet no systematic series corresponding in number
of divisions to the glacial stages has been found in orderly super-
position, and bearing the physical connections, or the fossils, necessary
for satisfactory correlation. The glacial waters were sterile, silty,
and cold, and hence not many fossils have been recovered from their
deposits at points where they are so intimately connected with the
ice deposits as to fix their time relations with certainty. It follows
that by far the larger part of the fossils whose exact relations to the
ice invasions can be fixed, are those which are found in the inter-
glacial beds. These, therefore, possess the highest order of value.
But even here no little circumspection is necessary to make sure that
the fossils were originally deposited contemporaneously with the inter-
glacial formations, and not introduced into them from earlier deposits
,by ice action or interglacial wash.
The Toronto beds. — By far the most instructive interglacial beds
thus far carefully studied in America are those on the Don River and
in the Scarboro cliffs, near Toronto, Ontario.1 The fossil-bearing
1 Coleman, Interglacial Fossils from the Don Valley, Toronto, Am. Geol., Vol. XII,
1894, pp. 86-95, with references to earlier literature, including Hinde's important
initial work; also Glacial and Interglacial Beds Near Toronto, Jour. Geol., Vol. IX, 1901,
pp. 285-310. Coleman and Penhallow, Canadian Pleistocene Flora and Fauna, Rep.
Com. Brit. Assoc., Bradford Meeting, 1900, pp. 328-339. Penhallow, Notes on Ter-
tiary Plants, Trans. Roy. Soc. Ca., Vol. X, 1904, pp. 56-76.
THE PLEISTOCENE OR GLACIAL PERIOD. 491
beds are underlain by a sheet of bowlder clay which has not yet been
positively correlated with its contemporary sheet in the series pre-
viously described. It can only be said that it is the equivalent of
one of the older drift sheets. The lowan has been suggested, but it
may perhaps equally as well be correlated with an earlier stage. This
basal sheet of till is succeeded by a horizon of erosion; and this, in
turn, by interglacial beds of stratified sand and clay reaching a maximum
thickness of more than 150 feet, the lower portion of which constitutes
the Don formation, and the upper portion, the Scarboro formation.
Above the latter is another horizon of erosion, which, in turn, is sur-
mounted by sheets of bowlder clay and assorted drift, together attain-
ing a maximum thickness of 200 feet, and referred to the Wisconsin
stages.
Recalling the ideal succession of faunas and floras of a typical
interglacial epoch, viz.: (1) arctic, (2) cold-temperate, (3) warm-
temperate, (4) cold-temperate, and (5) arctic, it is to be observed
that in the Toronto series the arctic and cold-temperate faunas, which
should theoretically have followed the retreat of the earlier ice, and
should have been recorded in order above the basal bowlder clay,
have not been identified. Their places are perhaps represented by
the erosion horizon between the basal bowlder clay, and the stratified
sands and clays of the Don formation.
The latter formation contains a warm-climate fauna and flora, and
is, therefore, assignable theoretically to the mild middle part of the
interglacial epoch. Up to 1900, the flora of this stage had yielded
to the industry of Coleman and others 38 species of plants distributed
through 26 genera, as identified by Penhallow. Many of these species
indicate a climate appreciably warmer than that of Toronto at present.
Among these are the p&wp&w , (Asiminia triloba) and the osage orange
(Madura arantiaca), which now flourish only in more southerly lati-
tudes. The maple, elm, ash, oak, hickory, basswood, etc., were pres-
ent, suggesting that this region was then forested with trees of types
which now flourish typically farther south. The whole group, accord-
ing to Penhallow, implies about such a climate as now prevails in the
middle United States, in latitudes 3° to 5° farther south.
The fauna of this stage contains about 40 species of mollusks, several
undetermined species of beetles and cyprids, an undetermined fish,
and possibly a mammoth or mastodon, and a bison. Among the
492 GEOLOGY.
mollusks, 11 species were unios, of which 4 are now living in Lake
Ontario, 3 are now living in Lake Erie, but are not recorded from Lake
Ontario, and 4 are not known in the St. Lawrence waters, but are now
living farther south in the Mississippi basin.
All these plants and animals had undoubtedly been driven entirely
out of the St. Lawrence basin by the previous ice invasion. The inter-
glacial interval must therefore have been long enough for a varied
fauna, containing many clams and other mollusks, and a complex
flora containing many forest trees, to migrate through at least several
degrees of latitude. This gives some suggestion of the importance
of the interval marked by the erosion horizon below the Don beds.
Above the warm-climate fauna and flora of the Don beds, there
is a cold-climate fauna and flora in the Scarboro beds, embracing 14
species of plants and 78 species of animals, 72 of the latter being beetles.
This assemblage implies a cold-temperate climate of about the type
which now prevails in the region just north of Lake Superior, or that of
southern Labrador. The arctic fauna and flora, which should theo-
retically have followed this cold-temperate one, heralding the imme-
diate approach of the next glacial invasion, is undiscovered. It is
probably unrecorded, its time-place falling within the long period of
erosion that intervened between the deposit of the Scarboro beds and
the formation of the overlying glacial bowlder clay.
Of the complete ideal series (arctic, cold-temperate, warm-tem-
perate, cold- temperate, and arctic), the third and fourth are well
recorded, while the rest are probably missing because they fell within
the erosion intervals. The later of these intervals, judged by the
amount of erosion accomplished, and by the changes of attitude or
the cutting down of the basin rim necessary to inaugurate and per-
petuate the erosion, are such as to indicate an interval as long as
the whole post-glacial epoch. It was therefore quite ample to account
for the non-appearance of the later or advancing arctic fauna and
flora. The horizon of earlier erosion is less well recorded physically,
but if it covers the time of the retreating arctic and cold- temperate
faunas and floras, it, too, was doubtless important.
It is obvious that the record implies a pronounced migratory oscil-
lation, but the full measure of this oscillation cannot at present be
very closely approximated. The record merely shows that the paw-
paw, osage orange, and their mild-temperate associates flourished in
THE PLEISTOCENE OR GLACIAL PERIOD. 493
latitude 43° 15' north, but how much farther north they extended
is only indefinitely implied by their apparent abundance and their
congenial associations in this latitude. Penhallow suggests an exten-
sion 200 miles farther to the northward.1 The ice had previously
reached about latitude 39° in Kentucky, and 37° 30' in Illinois. How
much south of the ice limit the pawpaw and osage orange were driven
by the cold zone bordering the ice-sheet, is at present rather a matter
of theoretical estimate than of direct evidence, and is differently placed
by different students of the subject, since at present quite divergent
views are entertained respecting the climatic conditions that sur-
rounded the ice-sheets. The best suggestion drawn from the existing
evidence is found in the southward migration of the larch or tamarac
(Larix}. At present, its southern limit is not far from the northern
limit of the pawpaw and osage orange. It overlaps the former a little,
and falls short of the latter. A fossil Larix has been recovered at
Dahlonega, Ga., latitude 34° 30', or about 480 miles south of its pres-
ent limit, and 300 miles south of the glacial margin. Its extreme
southern migration is undetermined, and may not improbably be
appreciably farther south. It is not unlikely that the northern limits
of the pawpaw and osage orange were forced as far south as was the
southern limit of the larch, thus preserving about their present rela-
tions. This would involve a total migration of at least 600 miles, and
not improbably 800 miles or more.
The fact that nearly all the plants of the Toronto beds belong to
existing species, while most of the beetles belong to extinct species,
is highly suggestive relative to contemporary differences in the stages
of evolution of associated organisms, and relative to varying rates of
evolution. It is in harmony with other evidence that the insects
were still in a state of rapid evolution, while the plants had more
nearly reached a static stage.
Other interglacial epochs. — In the Aftonian formation there is
evidence at many points of an ample growth of vegetation, recorded
in peat and muck beds, in humus-bearing soils, and in twigs, limbs,
trunks, and even stumps of trees. No great variety of life has, how-
ever, as yet been identified; more, perhaps, because the beds are not
fortunately situated for investigation, than from any probable dearth
1 Notes on Tertiary Plants, loc. cit., p. 69.
494 GEOLOGY.
of material. The formation is but scantily accessible except as arti-
ficially exposed. The wood found seems to be largely coniferous,
apparently white cedar (Thuya occidentalis). Sphagnum moss has
been identified by MacBride.
The Yarmouth horizon between the Kansan and Illinoian glacial
beds has yielded relics of the wood rabbit (Lepus sylvaticus) and of
the skunk (Mephitis mephitica).1 Peat, containing twigs, and humus-
bearing soils indicate a prevalent vegetation. To the Sangamon
horizon has been referred coniferous wood, the common peat moss,
Hypnum aduncunij and, doubtfully, Elephas primigenius. The Peoria
horizon carries peat accumulations. Between the two Wisconsin
stages of glaciation no important organic accumulations are known.
Marine life on the more northerly coasts. — During that stage of the
late Wisconsin glaciation when the eskers of Maine were being formed,
and the sea-level stood higher than now relative to the land in that
part of the coast, arctic mollusks abounded in the shore waters and
were buried in marine clays formed contemporaneously with the
eskers.2 From these marine beds, Packard has identified above a
score of mollusks, among which are species of Saxicava, Leda, Astarte,
Yoldia, Mya, and several other genera. The species have a northerly
range, and live in waters that are near the freezing-point most of the
year. There have been found also remains of walruses, seals, and
whales.
In the Champlain sub-stage, the last episode of the Pleistocene or
the opening episode of the Recent period, the arms of the sea that
occupied the lower St. Lawrence and Champlain valleys were peopled
by an ample marine fauna of essentially the same type as that which
now lives about the mouth of the St. Lawrence and on the coast of
Labrador. Some signs of progress in numbers and variety in the
course of the sub-epoch are suggested by the fact that the higher
beds are more fossiliferous than the lower ones. Two sub-faunas
have been recognized, that of the Leda clays below, and that of the
Saxacava sands above, but it is not yet quite clear how far this dis-
tinction represents a prevalent chronological succession, and how far
it is but a local adaptation to conditions of depth and bottom. The
1 McGee, llth A. Rep. U. S. Geol. Surv. Leverett, Mon. XXXVIII, U. S.
Geol. Surv., p. 42, 1899.
2 Stone, Mon. U. S. Geol. Surv., XXXIV, 1899, pp. 53-54.
THE PLEISTOCENE OR GLACIAL PERIOD. 495
marine life of the cold northeastern coast was, at the close of the Cham-
plain, merging into the existing forms, and these were shifting north,
ward into their present habitat.
Marine life on the more southerly coasts. — Away from the imme-
diate influences of the ice-sheets, the record of marine life does not
indicate any profound departure from the progressive modernization
that had been in progress through the Tertiary period. It has been
remarked by Dall that the Pleistocene fauna on the Atlantic coast
does not imply as cold waters as did the Oligocene fauna, and by Arnold
that the Pleistocene fauna of the California coast does not imply as
cool a climate as does the Pliocene fauna of that coast. It is to be
noted, however, that the known marine record does not presumably cover
more than a small part of the Pleistocene period, and that it is not
at all certain, or perhaps even probable, that the portion represented
was any one of the glacial epochs. When the ice was pushing into
the ocean on the coast of Maine, as in the Late Wisconsin epoch, and
an arctic fauna occupied that coast, it is scarcely probable that a warm-
temperate fauna lived on the southern coast; nor is it probable that,
when all the inlets of the coast of British Columbia, from Juan de
Fuca northward, were shedding icebergs into the Pacific, a warm-
temperate fauna lived along the California coast; but warm- tem-
perate faunas on those coasts are entirely consistent with such inter-
glacial climates as are represented by the Don beds, and they might
also have been quite consistent with the conditions that prevailed
just before or just after the glacial stages. These last fall within the
broader limits of the Pleistocene period, as it is usually defined in the
marine series. These limits probably do not correspond very closely
with the glacial limits which are usually adopted for the land series,
wherever glaciation prevailed.
The Terrestrial Life of the Non-glacial Regions.
As previously indicated, the land life of the regions distant from
the glaciated areas cannot at present be correlated closely with the
glacial and interglacial stages, and must be treated more generally.
One of its most marked features consisted of a northern group of indi-
genous and Eurasian origin, that appears to have been driven far
south during the stages of ice advance, and to have followed the retreat-
496 GEOLOGY.
ing ice well to the northward in the intervening stages of deglaciation.
Whether there was intermigration with Eurasia by the northeastern or
northwestern routes during the interglacial intervals, is not positively
determined, but it is not improbable. The great proboscidians, the
mammoth and mastodon, and the bear, bison, reindeer, and musk-ox,
were characteristic members of this group. With these, in the mid-
latitudes, were mingled several types on the verge of extinction in
North America, such as the horse, tapir, llama, and sabre-tooth cat.
A second prominent feature was a southern group consisting of
gigantic sloths, armadillos, and water-hogs, whose forebears had
come from South America when the isthmian route had been opened
in the Pliocene. There is perhaps room for question whether these
southern giants ever lived in the mid-latitudes after the first ice inva-
sion, though remains referred to the Pleistocene have been found as
far north as Pennsylvania and Oregon. If these really fall within
the glacial period proper, there must have been a northern migration
in some one or more of the mild interglacial epochs.
The boreal group. — As in the Pliocene, the proboscidians dominated
the fields and forests in mid-latitudes. A leading form was the
mammoth (Elephas primigenius or columbi) which ranged from the
southern states and Mexico northward probably to a fluctuating line
determined by the stages of glaciation. In interglacial stages, and
at the close of the glacial period, it seems to have ranged far to
the north, for remains have been found in Canada and Alaska. Siberian
species which have been kept in cold storage in underground ice or
frozen earth, show that the mammoth, there at least, was covered
with wool and hair and was obviously adapted to a cold climate. It
is not improbable that the southward range to Mexico represents the
mammoth's exceptional migration in front of the ice invasions rather
than a permanent occupancy of such low latitudes, for the mam-
moth is said to have been limited in its southerly range in Europe.
The Elephas survived the glacial period in America, and its tusks and
skeletons are not infrequently found in beds of peat and muck that
have accumulated in the shallow basins on the surface of the late Wis-
consin drift, in the northern United States and Canada, indicating
its presence there some time after the ice left the country finally.
The mastodon also ranged widely over the Northern States and
into Canada, as well as southward into the Southern States. Not
THE PLEISTOCENE OR GLACIAL PERIOD.
497
improbably its range also was shifted with the glacial movements;
but as it emigrated to South America and crossed the tropics, it can-
not have been ill-adapted to a warm climate, as perhaps the mam-
moth was. The mastodon likewise lived through the glacial period,
and is found in post-glacial deposits in middle latitudes. Williston
is authority for the suggestive fact that, while mammoths were very
FIG. 565. — An interpretation of Mastodon americanus by G. M. Gleeson.
(From painting in National Museum, Washington.)
abundant in Kansas and in the open plains where forests seem not to
have prevailed in Pleistocene times, the mastodon was almost exclu-
sively confined to the valleys and timbered regions, notably those
of the Eastern States, the Mississippi valley, and the foot-hills and shores
of the Pacific Coast. The mastodon has never been found on the
plains of Kansas, and the mammoth seldom in the formerly wooded
valleys. This calls in question the prevalent view that the presence
of the mammoth necessarily implied arboreous vegetation. Arboreous
vegetation, however, — of the minor type at least, — was present as
far west as Iowa and Dakota in some of the interglacial intervals.
498 GEOLOGY.
Several species of horses have been found in western beds referred
to the Pleistocene period. A gigantic elk ranged from Mississippi at
least as far northeast as New York, and in the interior as far north
as Kansas. Two or three species of buffaloes roamed over the Ohio
valley, and southward to the Gulf. The musk-ox (Ovibos), a thoroughly
arctic animal, nowr living on the very borders of the ice-fields, has
been found as far south as Virginia and Kentucky, as has also the
reindeer. A large saber-toothed cat mingled its remains with those
of Elephas in Oklahoma. The beaver-like Casteroides ohioensis is
known to have ranged from Ohio and New York, south to Missis-
sippi. Bears, rather recent emigrants from Eurasia, were present,
as were also wolves, peccaries, and the vanishing group mentioned
above.
The southern group. — Over against this assemblage of more or less
boreal forms that were pushed southward by glacial advances, there
was the group of South American immigrants, the monster sloths,
Megatherium, Mylodon, Megalonyx, and the gigantic armadillo, Glyp-
todon, the last covered by a strong carapace of sculptured ossicles,
and armed with a massive tail plated with spiked ossicles. The remains
of this group have been found chiefly in caverns and crevices, or in
the muck and mire about salt springs, or in fluvial deposits, the pre-
cise ages of which are difficult to fix, and it ought not to be very firmly
concluded that they were present during the glacial period, until their
remains are found in interglacial beds, or in demonstrable equivalents
of the glacial series. There is apparently nothing, however, in the
climatic conditions of such an interglacial stage as that which per-
mitted pawpaws and osage oranges to flourish about Toronto, to for-
bid their presence in the most northerly ranges in which their relics
are found, Pennsylvania and Oregon. Whether they could have held
their ground in North America when the ice-sheet reached southern
Illinois, is more problematical.
The European Pleistocene Life.
Oscillatory migrations. — A complete agreement as to the migra-
tions of faunas and floras in Europe during the glacial period is yet to
be reached, but the data have been sufficiently developed to justify
the tentative attempts that have been made to trace the oscillations
THE PLEISTOCENE OR GLACIAL PERIOD. 499
in detail. The following outline is borrowed essentially from the
writings of James Geikie.1
The earliest indications of an approaching ice age are met with in
the marine deposits of the late Pliocene period. The earlier Pleis-
tocene life indicates genial climatic conditions, but towrard the close
of this initial stage, marine forms adapted to mild temperatures retreated
from the North Sea, while boreal types came to occupy their place.
Similar migrations affected regions farther south, and many boreal
forms found their way into the Mediterranean. On the land, like
changes took place, and the luxuriant flora and the great mammals
of the Pliocene retreated before the advancing glacial climate.
During the first glacial epoch, a thoroughly arctic fauna lived in
the North Sea, while during the first recognized interglacial epoch
following, the arctic fauna retreated from the North Sea. On the
land, during this interglacial interval, a temperate flora, comparable
to that now existing in England, clothed the British Isles, while the
hippopotamus, elephant, deer, and other mammals invaded Britain
by way of the land bridge which then connected it with the conti-
nent. A similar flora and fauna advanced to corresponding latitudes
on the mainland. A luxuriant deciduous flora occupied the valleys
of the Alps and flourished at heights which it no longer attains. Towrard
the close of this interglacial epoch, the temperate flora retired, and an
arctic flora gradually took its place.
During the second glacial epoch, according to Geikie, the ice reached
its maximum extent in Europe, and arctic-alpine plants occupied the
low grounds of central Europe, while northern mammals, embracing
the reindeer, the arctic fox, and the arctic glutton reached the mountain
ranges of southern Europe, and even the shores of the Mediterranean.
During the second interglacial epoch, the arctic-alpine flora and
the northern fauna retreated over the lowlands of central Europe,
and were replaced by temperate and southern forms. The plants
which then occupied northern Germany and central Russia imply a
milder climate than the present, and the mammalian fauna, which
included the hippopotamus and elephant (Elephas antiquus), was in
keeping with the flora. Toward the close of this interglacial epoch,
however, a northern facies began to be assumed, and as the third gla-
1 The Great Ice Age, Third Edition, pp. 607-615.
500 GEOLOGY.
cial epoch came on, the northern types were pressed well to the south,
but not to the extreme extent of the preceding epoch.
The deposits of the third interglacial 'epoch embrace, in some places,
temperate marine faunas, and in others arctic forms. The mam-
malian fauna embraced the Irish deer, the horse, the mammoth, and
the woolly rhinoceros. The evidence favors the belief that the climate
became ameliorated to a degree congenial to a cool-temperate fauna,
but not to a warm-temperate or subtropical fauna.
During the remaining epochs, the oscillations were apparently
much less wide, ranging between cold- temperate and sub-arctic in
northern and middle Europe; in short, the to-and-fro migrations of
the life appear to have died away in oscillations of decreasing ampli-
tude, corresponding to the subsiding oscillations of the glacial stages.
The Pleistocene Life of the Southern Hemisphere.
Life in South America. — While the Pleistocene life of North America
and Europe bore a close similarity to one another, that of South America
had a character quite its own. The major fauna was composed of
two great elements, (1) the gigantic sloths and armadillos, which were
indigenous to that country, and (2) the descendants of the Pliocene
mammals which had migrated from North America. It is possible,
on the other hand, that a portion of the extinct South American fauna,
referred to the Pleistocene, really belonged to the late Pliocene. The
indigenous element of the fauna was rendered remarkable by the abun-
dance and extraordinary dimensions of the great extinct sloths and
armadillos. Among the northern immigrants were horses, masto-
dons, llamas, tapirs, wolves, and a large variety of rodents. The
gigantic character and seeming great abundance of the fauna, taken
as a whole, and especially that of the edentates, seems out of har-
mony with the repressive conditions which might reasonably be inferred
from the crowding of the faunas toward the tropics by the advance
of the glacial climates from the higher latitudes, and by its develop-
ment on the mountains and plateaus. It might naturally be antici-
pated that there would result a sharp struggle for existence, attended
by the destruction of the least adapted forms and the numerical reduc-
tion of the whole. Just such a reduction has taken place since, if not
then, and this seems to give some force to the suggestion that the
THE PLEISTOCENE OR GLACIAL PERIOD.
501
luxuriance of this great fauna really antedated the congestion attendant
on the maximum extension of the ice, and that the extinction of the
giant edentates, which seems to have followed their abundance some-
what closely, was connected with this extension. If this were true,
the fauna would be referred to the Pliocene and the earliest stages of
the Pleistocene and not to the later or true glacial Pleistocene.
Question as to current reference is perhaps warranted by the extreme
difficulty of closely correlating widely isolated formations in a transi-
tion period like the Pleistocene.
FIG, 566. — A club-tailed glyptodont, Dcedicurus clavicaudatus, from South America.
(After Lydekker.)
Australian life. — Owing to the isolation of Australia from the
Eurasian continent, its organic development followed lines of its own.
The vertebrate fauna consisted exclusively of marsupials and mono-
tremes. In general, they differed specifically from those now living,
and were larger, on the whole. The subsequent dwarfing was pos-
sibly due to the less genial climate of the ice age, and is perhaps to
be correlated in time as suggested above. Although the glaciers were
but slightly developed on the Australian mountains, the region doubt-
less felt the effects of the wide-spread refrigeration of the higher lati-
tudes, and of the aridity which seems to have accompanied some of
its stages.
Life in Africa. — Comparatively little is known of the Pleistocene
life of Africa. A moderate climate in the northern portion seems
502 GEOLOGY.
to be attested by fluvial accumulations which have yielded remains
of the buffalo, antelope, aoudad, hippopotamus, rhinoceros, and horse.
These appear to have belonged to an early stage of the Pleistocene.
A later stage is represented by mollusks of existing species, and a
mammalian fauna embracing the elephant, buffalo, hippopotamus,
urus, antelope, sheep, camel, and horse, a group differing widely in
the main from the present occupants of the region.
Man in the Glacial Period.
In America. — Previous to the last decade of the last century, no
small mass of prehistoric material of human origin had been assembled
and somewhat widely accepted as conclusive of man's presence in
America in glacial times. The rise of a more critical spirit in archaeo-
logic geology and the application of more rigorous criteria have, how-
ever, disclosed weaknesses both in the observational authentication
and in the interpretation of the material, and all these data have been
called into question, with the result that man's antiquity in America
is a more open question to-day than it was thought to be fifteen years
ago. While the doubts raised bore in some cases upon the human
origin of the objects, they lay for the most part against the geological
relations assigned them and the archseologic interpretations put upon
them.
Prehistoric human relics in America range from the rudest stone
chippings and flakings up through various gradations to skillfully
fashioned and often polished handiwork in stone, metal, bone, and
other material. The relics brought into question were chiefly, though
not exclusively, those of the ruder sort. Following European prec-
edent, the earlier students classed the rougher artefacs l as paleo-
lithic, and interpreted them as indicating the presence of Paleolithic
man and of the Paleolithic or Old Stone age in America. The better
fashioned artefacs were classed as neolithic, with corresponding refer-
ence to the Neolithic or New Stone age. Some investigators very
1 The term '' artefac " has been coined to designate, in a non-committal way,
any object that has been fashioned by man, in any way or for any purpose, or inci-
dentally without purpose. It includes stone chips, broken and rejected material,
and various forms of by-products, as well as implements, weapons, ornaments, etc.
Its special function is to avoid the infelicity of using the words implement, weapon,
etc., for objects that may never have been used, or even intended for use.
THE PLEISTOCENE OR GLACIAL PERIOD.
503
properly regard "paleolithic" and "neolithic" merely as stages of early
art, and not as chronological "ages," or geologic divisions, but the
terms have been much used in the latter sense.
The relics interpreted as paleoliths consist chiefly of rudely chipped
pieces of flint, chert, quartz, or quartzite (Fig. 567). With these are
associated other products of early art. The neoliths embrace a wider
range of stone artefacs, which may be briefly typified for our purpose
by the familiar well-chipped arrow-points, spear-heads, knives, and
scrapers of flint or quartz, and by the ground and polished axes, chisels,
pestles, mortars, and other implements of greenstone and similar
FIG. 567. — At the left, a typical paleolith from Kent's Cavern, Torquay, England,
seen on the face and edge. At the right, a bone pin or bodkin, a broken needle,
and a barbed harpoon head, also from Kent's Cavern. (After Evans.)
tough or workable rock. The ruder class were confidently inter-
preted as the work of an earlier and less cultured people, while the
better class were known to have been the customary implements
and weapons of the natives of the continent when first invaded by
Europeans. Stone hammers have been found in abundance in the ancient
copper mines of the Lake Superior region, and thus the use of stone
and of copper implements is shown to have been contemporaneous; but
this was long after the retreat of the last ice-sheet, and does not espe-
cially concern us here, except as it serves to emphasize the contem-
poraneity of different forms of art. It is helpful also to note that
the phase of the stone art designated neolithic was dominant on the
continent until very recent times, and is scarcely yet extinct, and that
504 GEOLOGY.
it was thus contemporaneous with the " Iron age " of Europe and entirely
overlapped the " Bronze age."
The chief points brought into question by the more critical inquiries
of recent years were (1) the reference of the ruder artefacs to a stage
of art more primitive than that of the Indians and other aborigines,
and (2) the reference of the gravels and other superficial formations
in which they were found to the glacial period.
By a series of notable investigations relative to the first, Holmes l
reached the firm conviction that the early inhabitants of the country,
like the later Indians, resorted habitually to gravel-beds and to out-
crops of appropriate rock to procure the rawT material for their stone
artefacs, and that it was their custom to test and to rough-out the
material on the ground, leaving the chippings and the rejected mate-
rial scattered about. This preliminary work appears to have been
done wholly by rough percussion with cobbles and other natural forms
of stone picked up on the ground and used as hammers. The roughed-
out flakes and other half-shaped forms that promised to work up prop-
erly, were usually taken to other sites for the finishing work. This
half-worked material seems often to have been cached in quantity,
and to have been material of trade. The more delicate and tedious
work of final shaping was apparently done more leisurely, and as need
required, at their dwelling sites or other convenient places, and to
have been done by skillfully applied pressure rather than by percus-
sion. An example of the refuse deposits on the face of the gravel
bluff from which the material was taken is shown in Fig. 568. A
selected series of rejects, showing progressive stages of reduction, is
shown in Fig. 569. A full series of the stages of manufacture, as thus
interpreted, is shown in Fig. 570.
By virtue of this separation of the process of manufacture into
two parts, there arose a geographic separation of the products, a fact
of importance in interpretation. The rude failures and rejects, together
with the extemporized hammer-stones, cores, flakings, and chips, were
scattered about the sites of the raw material, while the completed
implements were liable to become fossilized, as a rule, only about the
1 Holmes, W. H., A Stone Implement Workshop, Am. Arthropologist, Vol. Ill,
1890, pp. 1-26; Review. of the Evidence Relative to Auriferous Gravel Man in California,
Smith. Rept. 1900, pp. 417-472; Stone Implements of the Potomac-Chesapeake
Tidewater, Ann. Rept. Bureau of Eth., 1893-94, pp. 1-152, and Jour, of Geol., Vol. I.
THE PLEISTOCENE OR GLACIAL PERIOD.
505
dwelling sites, or wherever, in the course of their use, they were lost,
broken, or thrown aside. In the light of this definite separation, it
FIG. 568. — Portion of an extensive deposit of shop-refuse, near the quarry face in a
gravel bluff, on Piny branch, near Washington, D. C. (After Holmes.)
is not difficult to see how the similitude of two stages of art, of quite
different aspects and geographically dissociated, arose, arid how easily
they might be misinterpreted.
506
GEOLOGY.
THE PLEISTOCENE OR GLACIAL PERIOD.
507
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508 GEOLOGY.
The most available sites for finding suitable raw material in a con-
venient form were the river gravels and the terrace formations. This
was especially true in and about the glaciated regions where valley
trains of glacial gravels led away from the ice-fields. In these were
usually much quartz, flint, chert, and other available rock, in the con-
venient form of pebbles, cobbles, and bowlderets. This material had
been selected, as it were, and brought to workable sizes by the ordeal
of glacial wear and wash.
It is a significant fact that the rude artefacs in question have been
chiefly found in such gravels. Gravels derived from chert-bearing
limestone or quartz-bearing rock are also fruitful sources. In other
words,, there is a correspondence between the distribution of the ruder
artefacs, and that of the raw material. The distribution of the finished
artefacs is much wider and more varied, and hence more consistent
with the probable distribution of their use, and their liability to be
lost. There is a special infelicity in supposing that great numbers
of implements would be lost in glacial rivers during actual glacial
stages, for the waters of these rivers must have been cold, silty, and
barren of organic matter, as they came from the glacial mill under
the ice-fields. They must have been among the most uninviting of
all streams for hunting and fishing. But at later stages, when the
climate was milder and the streams warmer and clearer, and when
the adjacent country was filled with food and game, arid when also
the glacial gravels were undergoing readjustment and degradation,
and were being exposed in the bluffs and stream beds, these streams
must have furnished excellent and convenient grounds for finding
raw material for making stone implements.
The distinct recognition of the two stages in the manufacture of
the well known arrow-points, spear-heads, knives, etc., used by the
known aborigines of the country, and the strong evidence that mul-
titudes of the ruder forms found in the river gravels were products
of the first stages of such manufacture, naturally raised the question
whether there are any true paleolithic artefacs in North America.
The difficulties of discriminating between "paleoliths" and "rejects,"
if indeed they can be discriminated, is illustrated by Fig. 571, one of
the chipped blades of which has been regarded as a typical " paleolith,"
while the other forms are "rejects." Whether this close resemblance
be regarded as merely similitude or as actual identity, it is obvious
THE PLEISTOCENE OR GLACIAL PERIOD.
509
that a special burden is thrown upon the geological evidences, and
that they must be essentially decisive in themselves.
FIG. 571. — A group of figures of chipped-stone artefacs, one of which has been regarded
as a typical paleolithic implement, front and side view, while the rest were obtained,
in three cases, from modern flint-shops of the region in which the supposed paleo-
lith was found, while the fourth was traceable directly to the same shops. The
discrimination between the paleolith and the rejects is left to the reader.
(Holmes.)
It has been found that by far the majority of the artefacs in the
valley gravels are buried in the superficial portions, or in talus slopes,
510
GEOLOGY.
or in secondary deposits, many of which are comparatively recent.
Of the less superficial finds, many have been shown to be cases of second-
ary burial by natural means. The usual modes followed by streams
FIG. 572. — A gravel bluff formed by the under-cutting of the adjacent river.
(After Holmes.)
in cutting down their channels in valley gravels are peculiarly well
suited to bury superficial material to very considerable depths, for
in their meanderings they cut into the bordering terraces or uplands
FIG. 573. — The same at an early stage of talus formation.
at intervals and develop steep bluffs. When the meanders shift,
as they are sure to do, the bluffs inevitably grade down to a slope by
the falling, or sliding, or washing of the top to the bottom, as illus-
FIG. 574. — The same at a late stage of gradation, when the slope has become
nearly stable.
trated in Figs. 572-574. What was in the top portion naturally
becomes part of the base of the talus, and is deeply buried. Similar
secondary burials take place in various kinds of loose material, includ-
THE PLEISTOCENE OR GLACIAL PERIOD. 511
ing loess and fluvial deposits of all sorts. It is to be noted that this
is a prevailing habit, and not an exceptional mode of action.
While lateral action of this kind seems to have been the most com-
mon mode of burial of artefacs and other superficial material, other
systematic methods are recognized.1 One of the more important arises
from the scour-and-fill of streams when they run on beds of gravel,
sand, silt, or other loose material. The irregularities of a stream's
flow, particularly the swirls and rolls developed by its meanders, give
rise to shallows and deeps, and constantly shift them so that in time
they cover nearly, or quite, the whole of the bottoms occupied by
the stream. Similar action is to be assigned to all stages in the past
history of the stream, and, hence, any article found in an abandoned
terrace may as well be assigned to scour-and-fill just before the stream
abandoned it, as to any earlier period. A valley train, heading at the
ice-edge and hence usually called glacial without hesitation, is sub-
ject to this re-working process as long as the stream flows over it. The
depth of re-working is readily measured by the depths of the deeper
parts of the streams below their flood-plains, for it is known that these
deeper parts are filled before the river bottoms become flood-plains
or terraces. The depths thus re-worked very commonly range from
one to three score feet for small rivers, and up to five or six score for
large streams (Vol. I, p. 195), and in some cases, reach even three
and four hundred feet. In view of this, no relic found in fluvial mate-
rial can, with full safety, be referred to an age older than the last stages
at which the stream flowed over its surface.
Almost none of the glacial gravel trains were at once abandoned
by their streams, except in certain portions immediately adjacent to
the ice-border; indeed most of the glacial gravel trains were built up
in their lower stretches for some time after the glacial feeding stopped.
This was done by the transfer of material from the high-gradient por-
tions near the ice-edge, to portions of lower gradient below, as an inevi-
table consequence of the substitution of clearer waters for the over-
burdened glacial waters. There is then very little assurance that
an implement, even if found deep in a glacial gravel train, was buried
while the ice was present, unless it is found in the unshifted portions
immediately at the ice-edge, and the topography and relations give
1 Criteria requisite for the reference of relics to a glacial age. Jour, of Geol., Vol. XI,
1903, pp. 64-85. Some methods not mentioned in this work are there discussed.
512 GEOLOGY.
full assurance that the particular portion involved was not shifted. Because
of this fundamental difficulty, and of the great liability to misinter-
pret the secondary burials previously described, and because of some
other contingencies we cannot here discuss,1 it is scarcely possible
to make out a good case of proof of contemporaneity with an ice stage,
from relics found in river gravels, unless the inherent evidences con-
nected with the relics themselves are altogether convincing.
All surface formations, however perfect their integrity in other
particulars, are subject to surface disturbances, and to the intrusion
of surface objects, through (1) the overturning of trees, (2) the pene-
tration of roots, their subsequent decay, and the filling of the root-
holes, (3) the burrows of animals, (4) earth-cracks developed by
drouth, and various other incidental agencies. Wind-blown dust and
sand also bury surface objects. All loose formations, glacial or other-
wise, are subject to secondary modifications in these and other ways,
to degrees and extents only appreciated by special students of such
phenomena.
There is a rather important class of recomposed formations made
by the shifting or rehandling (by eolian, pluvial, fluvial, slumping,
and other processes) of drift, loess, or alluvium, which so closely simu-
lates the original formations of like class as to deceive geologists of no
little experience. Some of the supposed evidences of man's antiquity
that seem, on their faces, to be strongest, are but cases of burial beneath
such recomposed formations of comparatively recent date. Occasional
burials of relics to depths of many feet may, therefore, carry little
weight.
Sources of good evidence. — There are two classes of formations in
which good evidences of glacial man, if there was such man in America,
are to be sought, viz., (1) in undisturbed till-sheets below horizons
affected by surface intrusion, and (2) in interglacial beds, where over-
lain by till and protected from all assignable sources of subsequent
intermixture. Both these classes of beds have yielded fossils of other
forms of life, and these alone have been seriously considered in the
usual studies of the life of the glacial and interglacial stages. Thcne-
beds have not yet yielded human relics in America, but they should
do so in time, if man was a member of the faunas of glacial or inter-
glacial times.
1 Jour, of Geol., XI, 1903, pp. 74-75.
THE PLEISTOCENE OR GLACIAL PERIOD. 513
In Europe, cave deposits have afforded a very important part of
the evidence of man's antiquity, by showing that he was contem-
poraneous with a considerable number of animals that have become
extinct, and by inherent evidences of age. In America the evidence
of the caves is thus far essentially negative in this respect, the
relics of man in caves being associated with the living fauna, with
perhaps one or two doubtful exceptions. The mammoth and masto-
don, as already noted, lived after the last known glacial stage, and
very likely some other extinct animals did, so that an argument from
association with extinct animals comes to have force only when the
relics of man are associated with a large number of extinct animals
which carry evidences, or at least the presumption, of having died out
before the last glacial stage. In the American caves there is little
or nothing in the depth or method of burial to imply great age.
When the weakness of the cave evidence is joined to that of the
gravels and other loose deposits, and to the absence of authentic evi-
dence from the glacial tills and the interglacial deposits whence the
higher order of evidence is chiefly to be derived, presumption seems
to lean to the negative side of the question, and an attitude of sus-
pended judgment seems to be required. Proof of the negative prop-
osition that man was not in America during the glacial period is
not to be expected. His absence may in time come to be assumed,
if good evidence of his presence shall not be forthcoming after due
investigation under the more critical methods which the case requires
and is sure to receive.
In Europe. — The question of man's presence in Europe during
the glacial period is altogether independent of the American problem.
The balance of evidence is wholly in favor of the eastern continent
as the place of man's origin, and hence the dates of his migration to
America, and of his appearance in Europe, respectively, are as inde-
pendent as are the respective dates at which the Aryans entered the
two regions. There is little doubt that the European data might
well be subjected to more severe criteria, both archseologic and geologic,
and that some at least of the data from the gravels and other loose
formations would be found to have but little value. There are, how-
ever, some important differences between the European and the Ameri-
can data. The European are greatly superior in the mass of mate-
rial gathered directly by geologists and archaeologists, under condi-
514 GEOLOGY.
tions of satisfactory scientific control. The European cave evidence
seems to have no strict counterpart in America. In Europe there
are numerous caves in which the relics of 'man, mingled with those
of many extinct animals, have been securely protected by layers of
stalagmite. While the ages of the stalagmite layers have rarely been
fixed with certainty, or well correlated with the glacial stages, they
bear inherent evidence of considerable antiquity.
The association of man with extinct animals is a phenomenon
that may mean the extension of man's presence backward, or the exten-
sion of the animals' presence forward, and to this double-faced prob-
lem research has not yet furnished a final key. Obviously, however,
the larger the number of animal types not known to have lived this
side the last glacial stage whose remains are commingled with human
relics, the stronger the presumption of man's presence before the close
of the glacial period. From this point of view, the European case
seems to be strong, while the American is weak.
There is one further feature in the European case that is, at least,
suggestive. Two climatic classes of animals are associated with the
human relics, according to various European writers, — a sub-arctic
and a sub-tropical. Besides these, there are intermediate groups of
temperate aspect, but these do not carry equal significance. On the
sub-arctic side, there were reindeers, mammoths, woolly rhinoceroses,
arctic gluttons, musk-oxen, and other boreal forms; on the sub-tropical
side, there were lions, leopards, hippopotamuses, hyenas, southern
rhinoceroses, and other African types. These contrasted groups, as
interpreted by James Geikie and others, imply migrations of the kind
already sketched as characteristic of the glacial period. While it
cannot be positively affirmed that there were no climatic oscillations
of a similar kind after the ice invasions ceased, there is a somewhat
strong presumption that those implied by these two classes of animals
were identical with some of the recognized climatic oscillations of
the glacial period. This presumption connects man with at least the
later of the glacial epochs.
The relics thus associated with extinct animals have been assigned
to paleolithic man, and to a primitive stage of culture. They have
been interpreted rather by the crudeness of the rude stone artefacs
than by the evidences of a higher order of art which the record pre-
sents. If, however, the rude stone artefacs are susceptible of being
THE PLEISTOCENE OR GLACIAL PERIOD.
515
interpreted as the incidental products of preliminary processes in the
production of a higher class of stone art, — an interpretation which
does not seem to have been fully adjudicated, as yet, in Europe, —
FIG. 575. — Etching of reindeer on a slab of slate, from the bone cave of Les Eyzies,
Dordogne, France (| size). The next figure is from the opposite side of the same
slab. (From a photograph, Prestwich's Geology.)
FIG. 576,-^Sketch of an aurochs on the opposite side of the slab of slate showing
the reindeer above. These sketches may be instructively compared with the
similar work of the ancient Assyrians and Egyptians.
a more favorable judgment of the art of these ancient peoples would
appear to be required by the other classes of relics found. There
were associated with the stone artefacs, implements of bone, such as
needles with perforated heads, awls or bodkins, harpoons or spears
516 GEOLOGY.
with barbs, etc., implying some advance in art; there were carvings
that show not a little skill, and drawings in which the elements of
perspective and shading, as well as skill in delineation, are indicated
(Figs. 575 and 576). These seem to imply a higher stage of art develop-
ment than is obviously consistent with a limitation in the use of stone
to the very crude forms called paleolithic. However this may be,
present evidence seems to justify the conclusion of most European
archaeological geologists, that man was present in southern and central
Europe during the later part of the glacial period.
Other references relative to the antiquity of man: Abbott, C. C., Primitive In-
dustry, Peabody Acad. Sci. Salem, 1881 ; A recent find in the Trenton Gravels,
Proc. Bost. Soc. Nat. Hist., Vol. XXII, pp. 96-104, 1884; On the antiquity of
man in valley of Delaware, Proc. Bost. Soc. Nat. Hist., Vol. XXIII, pp. 424-
426, 1888; The Stone Age in New Jersey, Smiths. Rept. 1875, and Pop. Sci.
Monthly, Dec., 1889; Primitive industry, 10th Ann. Rept. of Peabody Museum,
p. 41. Babbitt, F. E., Vestiges of glacial man in Minnesota, Am. Nat., Vol.
XVIII, pp. 594-605, 697-706, 1884. Becker, G. F., Antiquities from under
Tuolumne Table Mountain in Cal., Bull. Geol. Soc. of Am., Vol. II, p. 189. Blake,
W. P., The Pliocene skull of California and the stone implements of Table Moun-
tain, Jour, of Geol., Vol. VIII, 1899, p. 631. Calvin, S., Lansing Man, Jour,
of Geol., Vol. X, pp. 745 et seq. Chamberlin, T. C., Lansing Man, Jour, of Geol.,
Vol. X, pp. 745 et seq. Geikie, James, The Great Ice Age, pp. 616-690; also,
Prehistoric Europe, pp. 568 et seq. Gilbert, G. K., On a prehistoric hearth
under Quaternary deposits in western New York, Sci. Am. Supp., Vol. XXIII,
pp. 9221-9222, 1887. Lyell, Sir Charles, Antiquity of man. McGee, W J, The
Geology and Archaeology of California: Abstract, Am. Geol., Vol. XXII, pp. 96-
126; Sci., new ser., Vol. IX, pp. 104-105; Sci. Am. SuppL, Vol. XLVII, p. 19313,
1899. Salisbury, R. D., Lansing Man, Jour, of Geol., Vol. X, pp. 745 et seq.; On
origin and age of the relic-bearing sand at Trenton, N. J., Sci., new ser., Vol. VI,
pp. 977-981, 1897. Skertchly, S. B. J., On the occurrence of stone mortars in the
ancient river gravels of Butte Co., California, Jour. Anth. Inst., May, 1888. South-
all, Recent origin of Man, p. 502: Upham, Warren, Geology of deposits containing
supposed vestiges of man in Minnesota ; Lansing Man, Science, Vol. XVI, pp. 355-6;
Amf Geol., Vol. XXX, pp. 135-150, and Vol. XXXI, pp. 25-34. Whitney,
J. D., Notice of a human skull recently taken from a shaft near Angels, Cala-
veras Co., Cal., Proc. Acad. of Sci., Vol. Ill, pp. 277-278; Am. Jour. Sci., 2d
ser., Vol. 43, pp. 265-267, 1867; The auriferous gravels of the Sierra Nevada of
California, Cambridge, 1879. Williston, S. W., Lansing Man, Science, new
ser. Vol. XVI, pp.. 195-6. Winchell, N. H., Lansing Man, Bull. Geol. Soc. of
Am., Vol. XIV, pp. 25-34, and 133-152; Am. Geol., Vol. XXX, pp. 189-194;
also Vol. XXXI, pp. 263-308. Wright, G. F., The glacial phenomena of North
America relative to the antiquity of man in the Delaware valley, Bull. Essex
Inst., Vol. XIII, pp. 65-73, 1882; Preglacial man in Ohio, Ohio Arch, and Hist.
Quart., Dec. 1887; The Ice Age in North America and its bearings upon the
antiquity of man, pp. 506-571; Remarks on the nature and history of deposits
in which a chipped implement was found in Jackson 60., Ind., Proc. Bost. Soc.
Nat. Hist., Vol. XXIV, p. 151, 1889; Man and the Glacial Period, pp. 243-307;
Recent discoveries concerning the relation of the Glacial Period in North America
to the antiquity of man, Brit. Assoc. Adv. Sci. Rept. for 1891, pp. 647-649, 1892.
CHAPTER XX.
THE HUMAN OR PRESENT PERIOD.
The end of the Glacial period. — The termination of the Pleisto-
cene or Glacial period is usually placed at the time when the ice-sheets
disappeared from the lowlands in the middle latitudes of Europe and
North America. Notwithstanding this conventional usage, it is to be
noted that the ice-sheets had not then completely disappeared, and
have not even now, for about 10% of the recently glaciated area of
North America is still buried in ice. This lies chiefly in Greenland,
the most central and northerly of the areas of glacial radiation in the
permanent low-pressure area of the North Atlantic, and subordinately
in Alaska, in the northeastern portion of the permanent North Pacific
" low." These lingering residues of the last Glacial epoch signalize the
fact that a complete emergence from the characteristic features of the
Glacial period has not been reached.
If the speculative conception that the deep-sea circulation was
actuated by evaporation in the low latitudes during most of the geo-
logical periods, and that this circulation was reversed by low polar
temperatures in the glacial periods only, be true, the reversal in this
circulation, when it shall take place, will constitute the really radical
limit of the Glacial period; for when dense, warm, saline waters shall
occupy the depths of the ocean, and emerge in the high latitudes,
giving them mild climates, glacial conditions will have disappeared
most effectually, and typical warm uniform climates, such as affected
most geological periods, will have returned. This is, of course, hypo-
thetical, and has its chief value perhaps in loosening the hold of our
too-fixed presumption that the present atmospheric and oceanic con-
ditions are normal for a late stage of the planet's history.
Future glaciation. — It is not absolutely clear that there may not
be another recrudescence of glaciation before this series closes, but
517
518 GEOLOGY.
the probabilities seem to be much against it. The declining series of
oscillations already noted seems to have reached its last term. If
carbon dioxide is an influential factor, its artificial production, which
is rapidly increasing, appears likely to more than offset the consump-
tion by natural processes, and hence to tend toward amelioration of
climate; but the factors that cooperate to produce glaciation are too
complex, in our view, to warrant more than a comfortable presumption
of future immunity from ice-invasions until another great deformation
shall have taken place in the distant future.
The end of the deformation period. — So, also, it is not wholly clear
that the deformative period which started in the late Tertiary, and
extended through the Pleistocene, is yet completed. We are accus-
tomed to regard it as essentially passed, notwithstanding some move-
ments still in progress; and, in the main, this seems to be justified
by the probabilities of the case. It is uncertain whether the existing
and very recent movements are to be regarded as portions of the main
deformative movement, or as secondary adjustments following the
main movement, or as but instances of the class of gentle movements
that are ever in progress, even if we do not raise the question, as some
geologists would, whether there is any real periodicity of movement
at all.
The region of the lower St. Lawrence has been elevated relatively
since the retirement of the ice, as is well attested by fossiliferous marine
beds, and by shore-lines 600 feet above the present sea-level. This
movement seems to have affected the North Atlantic coast from New
England northward, but quite unequally at different points. It has
been suggested by several writers that this relative rise might be chiefly
a resilience from the depression due to the weighting and cooling which
the region had suffered during the glacial stages.
A recent movement in the region of the Great Plains seems also
to be suggested by certain physiographic features. Extensive tracts
in central Kansas and Nebraska bear an aspect of pronounced topo-
graphic youth, suggesting that they have been lying, until recently,
near the neutral horizon between erosion and deposition, and have
lately been raised on the western side. In the Dakotas, there are
broad gradation plains of abandoned river-courses which cross the
present valley of the Missouri River. Their present gradients, and
their elevation above the present river-bottoms of the region, also
THE HUMAN OR PRESENT PERIOD. 519
imply a westward elevation. These and collateral phenomena, taken
with the remarkable movement of the Keewatin ice-sheet from what
is now the lower to what is now the higher side of the plains, seem
best satisfied by the view that until about the close of the Glacial period
the western side of the Great Plains was lower than now, or the eastern
side higher than now, relative to the common surface-level. The
composite view, that the area under the great ice-sheet was relatively
depressed and the area on its western border relatively elevated, is
perhaps the best special interpretation. On the western side of the con-
tinent there is much evidence of recent movement, some of which
appears to have taken place since the close of the Glacial period, as
usually defined. Similar phenomena affect other continents.
It is not therefore wholly clear whether the present is to be regarded
as a part of that time of deformation which had its climax in the Plio-
cene, or whether it belongs rather to the initial stage of a period of
quiescence that is yet to develop characteristically. It may perhaps
best be regarded as a transition from the one to the other.
In any case, two movements are probably peculiar to it : (1) the
elevation of the glaciated surface due to the removal of the weight
of the ice-sheet and its return to a normal temperature, and (2) the
restoration of the water temporarily locked up in the ice-sheets to
the ocean, which tended to raise the sea-level, while the removal of
the attraction of the ice-mass and the accompanying change in the
position of the earth's center of gravity tended to cause the waters to
recede from the glaciated region.1 When the special effects of these
exceptional agencies are deducted, the amount of the post-glacial
movement is appreciably reduced, which is favorable to the view
that the earth is now passing slowly into a period of quiescence.
The suggestions of existing physiography. — This view is further
strengthened by the present physiographic features of the earth's sur-
face. These are a direct inheritance from the Tertiary deformations
superposed upon pre-existing configurations. They have been modi-
fied by the gradational agencies that have been working since, includ-
ing the recent glaciation. They should tell us whether the face of
1 The attraction of the ice-mass is discussed mathematically by R. S. Woodward,
Bulletin U. S. G. S., No. 48, 1888; also, 6th Annual U. S. G. S., 1884-85, pp. 291-97.
The effects of the accumulation and the melting of ice are discussed by Croll,
Climate and Time, 1890, p. 388.
520 GEOLOGY.
the earth is that of a planet in the midst of deformation, or that of
one recently deformed, and now returning to a more quiescent state.
On critical examination every stream should tell whether it has just
been rejuvenated, or has done some notable work since it was reju-
venated, and whether the amount of rejuvenating influence is still
being increased, or is static, or is being diminished. Every coast
should show whether the continental border stands forth in the manner
typical of an earth-segment just crowded up by a deformative thrust,
or whether it has made some notable progress in settling back, or in
being cut back, to an inter-deformative state.
The streams of the continents almost universally show that since
they were rejuvenated they have had time to do some appreciable
work, except in the case of small streams entering the deepened valleys
recently occupied by glaciers, and the limited work of these only
emphasizes the time implied by those streams that have done appre-
ciably more work. Falls which owe their origin to the deformations
of the recent deformative period abound on all the continents, but
they are almost universally attended by canyons below, that show a
period of activity of appreciable duration. These falls and canyons
are often so related to slack water below as to show that the rejuvena-
ting process was stopped some time ago; indeed it has often been
reversed, as illustrated by the falls of the Potomac, and the rapids of
the " Fall line " of the Atlantic border generally, and the depressed
valleys below. The Falls of the Columbia, Congo, Zambesi, Brah-
maputra, Yang-tse, and of a multitude of other rivers descending from
the elevated portions of the continents, are also illustrations in point.
If the various criteria of topographic age set forth in Volume I be
applied to the face of the continents, it will be seen that, while they
betray, very generally, evidences of rejuvenation by deformation in
relatively recent times, there is very little to indicate rejuvenation in
progress, except in features that are obviously local and special. While
evidences of various degrees of aging are nearly everywhere displayed,
the areas that bear the most declared evidences of topographic youth
are those recently abandoned by the ice-sheets of the last glacial stage,
and the ice-invasions seem to be the youngest of the rejuvenating
agencies.1
If attention be turned to the borders of the continents, significant
1 Jour, of Geol., Vol. XII, p. 707.
THE HUMAN OR PRESENT PERIOD. 521
evidence is found in the fact that almost nowhere does the real edge
of the continent appear above the ocean. Very generally it lies 100
fathoms below sea-level, and a continental shelf almost universally
borders the continents. An area of 10,000,000 square miles, or more
than 15% of the true continental surface, is thus submerged. This
submergence took place so recently that the shelves are quite gen-
erally marked by trenches, valleys, and embayments referable to
rivers that formerly crossed them, and which have not yet been con-
cealed by sedimentation. These features imply that the continent
was recently so deformed that these shelves were out of water, and
that the rivers reached the true borders of the continental platforms.
They equally imply a general movement toward continental submer-
sion since, such, perhaps, as characterized many periods of past geologic
history.
In passing, it is important to note that the almost universal pres-
ence of submerged continental borders has a very significant bearing
on the fundamental question whether continental movements are
simultaneous or reciprocal. If such movements were reciprocal, some
continents should now be in the protuberant phase, with their borders
as pronouncedly out of water as other borders are submerged. So,
retrospectively, some should show marked participation in the ele-
vation of the late Tertiary, while others should show as marked par-
ticipation in the reciprocal submersion. In fact, however, all con-
tinents show signs of recent protrusive movement, and all show, by
their trenched continental shelves, the early stages of a common move-
ment of the sea upon the land.
The channels on the continental borders. — Wherever the conti-
nental shelves have been carefully explored by soundings, their sur-
faces show channels of river-like aspect, as already remarked. The
fjords and submerged valleys of the northern coasts are the most familiar
examples, as they have been much appealed to in support of the ele-
vation hypothesis of glaciation.1 The data in more southerly lati-
tudes, especially on the Atlantic Coast from the Gulf of St. Lawrence
to the Antilles, have been developed and emphasized by J. W. Spencer; 2
1 Among many others, Dana, Man. Geol., pp. 946-51 ; Upham, Bull. Geol. Soc.
Am., Vol. X, 1898, pp. 5-10.
2 Among other papers, Bull. Geol. Soc. Am., Vol. VI, 1895, pp. 103-140, and Vol.
XIV, 1903, pp. 207-226; Am. Jour. Sci., Vol. XIX, 1905, pp. 1-15; and Am. Geol.
XXIV, 1904, pp. 110-111.
522 GEOLOGY.
those on the east side of the Atlantic by E. Hull,1 by Nansen,2 and
others; and those of the Pacific by Geo. Davidson.3 Many channels
are so connected at the coast-lines with existing rivers as to leave
no reasonable doubt that they are but submerged portions of the
seaward extremities of the former channels of these rivers. Others,
notably some on the California coast, are not so connected; but even
these are usually interpreted as old drainage-valleys cut while the
border of the continent was above sea-level. Besides these there
are channels of more doubtful interpretation. Fjords, and the sub-
merged shelf- valleys connected with them, are very numerous in the
glaciated regions of both hemispheres, and undoubtedly owe some
of their features, and perhaps some of their abundance, to glaciation;
but Spencer,4 Hull, Davidson, and others have shown that such sub-
merged valleys are not confined to high latitudes or to glaciated regions.
They appear to be phenomena common to essentially all coasts. Some
of the best examples are the deep channels off the mouths of the Congo,
the Indus, and the Ganges in low latitudes. Not only do channels
cross the continental shelves, but troughs interpreted by Spencer and
Hull as their continuations descend the abysmal slope on the outer
edge of the continental platforms, to depths ranging from 7000 to 12,000
and even 14,000 feet; in other words, practically to the bed of the
ocean. On the edge of the continental shelves, deep canyons have
been identified, as the Hudsonian Channel, about 3800 feet deep.5
These channels have usually been interpreted as evidence of vertical
elevations of the continents whose borders they affect. The inter-
pretation has usually been extended to the bodies of the continents,
or at least to large portions of them. With the present evidence that
essentially all continental borders are thus affected, and that the depths
are in some cases nearly equal to those of the average ocean itself, a severe
strain is put upon this interpretation, not only because of dynamical
and faunal 6 objections, but because of the difficulty of disposing of the
1 Trans. Victoria Inst., Vol. XXX, 1897, pp. 305-324; also idem, 1900 and 1902,
and Geog. Jour.. 1899.
2 Rep. Arc. Expl., 1904, pp. 232.
3 Proc. Cal. Acad. Sci., Vol. I, 1897, pp. 73-103.
4Loc. cit.
5 Spencer, The Submarine Great Canyon of the Hudson River, Am. Jour. Sci.(
Vol. XIX, 1905, pp. 1-15.
8 Dall, Tertiary Fauna of Florida; Wagner Free Inst. Ser., Vol. Ill, 1904, p. 1544.
THE HUMAN OR PRESENT PERIOD. 523
water of the ocean when all the continents are lifted some thousands
of feet, and because of a special difficulty of this kind involved in the
fact that these valleys descend into closed basins such as the deeper
parts of the Mediterranean and Caribbean seas and the Gulf of Mexico,
which might naturally be supposed to retain so much of their waters
as lies below the lowest notch in their rims however much they were
carried up by epeirogenic movements. There are also difficulties con-
nected with the forms and the gradients of the valleys.1 The views
of deformation outlined on previous pages (Vol. II, pp. 233-235) afford
a different mode of interpretation, in which lateral movement plays
a larger part, and vertical movement a lesser part, and in which the
warping of the border of the continents replaces a movement of their
general mass. This interpretation also embraces other border phe-
nomena which need to be noted before the interpretation itself is
offered.
Upward warping near the coasts. — Nearly every coast is bordered
by inlets which are almost invariably submerged valleys; but, fol-
lowed inland, these inlets usually graduate into deep sluggish rivers,
and these, farther inland, are very often replaced by rapids or falls,
or at least by steepened gradients. When the continental borders are
examined throughout their full extent in all latitudes, the prevalence
of this phenomenon becomes impressive. The chief exceptions are
the great rivers which drain interior basins through broad gaps in
the elevated tracts that so generally border the continents, as the
Mississippi, which issues through the great gap between the Appa-
lachians and the mountains of Arkansas and Indian Territory, and the
Amazon, that issues between the Parima and the Brazilian mountains.
A critical study of the gradients of the normal coast-border river-
channels, embracing at once the submerged portions, the inlet por-
tions, and the high-gradient portions, indicates a warping rather than
a simple uplifting and depression, such as is implied in the epeirogenic
conception. This is an important factor in the alternative interpre-
tation.
The apparent imperfection of the geologic series on the continental
borders. — It is most logical to infer that, as the continents were already
outlined as early as Paleozoic times, persistent accumulation of sedi-
1 Kummel, Jour. Geol., Vol. Ill, 1895, p. 367.
524 GEOLOGY.
ments should have been in progress about the borders of the conti-
nents ever since, and that there should have been built out from the
borders a systematic series of Paleozoic, Mesozoic, and Cenozoic ter-
ranes, forming a distinct fringing zone. In this zone we might expect
to find the most complete of all the stratified series, embracing repre-
sentatives of all the ages and all the transitions, for on the borders of
the continents sedimentation should rarely, if ever, have been wholly
interrupted. This theoretical deduction is so strong that its verity
can scarcely be doubted.
But an inspection of the geology of the coast-belts, as at present
exposed, reveals the significant fact that not only is this theoretical
deduction far from realized, but that the stratigraphic series is there
singularly imperfect, indeed much inferior to that of the continental
interiors.1 The northeastern coast of North America and nearly
the whole coast of Greenland are formed of Archean and Proterozoic
formations, and the whole of the later series is essentially wanting.
From Newfoundland to New York, the coast formations are mainly
divided between the pre-Paleozoic and Paleozoic, with very scant
representation of the Mesozoic and Cenozoic eras. From New York
southward, Mesozoic and Cenozoic terranes have a fair, but not impres-
sive development, while the Paleozoic are scarcely identifiable outside
of the crystalline belt. On the west coast there is an intricate series,
much interrupted by crystallines of more or less doubtful ages, which,
if it could be fully interpreted, might more nearly fulfill theoretical
expectations; but this is uncertain. In South America, long stretches
on the northeast and southeast borders consist of crystalline rocks of
ancient aspect, save for narrow tracts of younger beds on the immediate
coast. There is no suggestion of a great systematic series. The eastern
coast-tract of Patagonia more nearly meets expectations relative to
the later periods, in that it constitutes a wide sloping plain of sedi-
ments heading at the Cordilleran axis on the west, and dipping beneath
the Atlantic on the east; but this seems to be rather an extension of
the interior plain of the La Plata basin than a typical fringing
series. On the west side of South America, crystalline rocks, some
of older, some of younger age, form complex terranes along or near
the coast throughout more than half the length of the continent, while
1 The geological maps in Berghaus' Physical Atlas afford the means for such an
inspection.
THE HUMAN OR PRESENT PERIOD. 525
the sedimentary series for the remaining distance seems to be com-
plicated and imperfect. On the borders of Europe, from the White
Sea to the Skager Rack, little beside Archean and Proterozoic ter-
ranes appear, while the later terranes are mainly unrepresented. In
Scotland, Wales, Ireland, Normandy, and the Spanish peninsula,
ancient crystalline rocks, interspersed with Paleozoics, largely occupy
the coast or closely approach it. A crystalline belt is represented as
lying a little back from the coast throughout nearly the whole extent
of the western side of Africa, and this is scarcely less true of the eastern
side. Although newer formations lie between this and the coast,
they represent, according to present knowledge, but a small part of
the post-Proterozoic series. The southern and eastern coasts of Asia
are occupied by a much-interrupted succession of various formations
in which none are conspicuously dominant, and no systematic series
is indicated. The protruding peninsulas of India, Anam, and Korea
seem to be largely formed of very ancient terranes, except some little
fringings of quite recent deposits. In Australia, crystalline and Paleo-
zoic rocks are predominant at or near the eastern coast and along
much of the western, and there is little or no suggestion of an
encircling belt of sediments systematically representing outward growth
of the land.
And yet in the interior of all these continents there are great series
of sediments recording much more fully the progress of the ages. If
our knowledge of the progress of events were limited to coast-border
series, it would be imperfect indeed.
None the less, we must believe that the theoretical continent-
bordering series exists, and for ourselves we do not question that it
is absolutely continuous, in its deeper parts, from the Archean to the
present time. There must therefore be agencies in play other than
the mere systematic lodgment of sediments about the continental
borders, and these agencies have persistently disturbed the border
record. If the mutilated record of the border-sedimentation be asso-
ciated with the deep trenches of the surface and abysmal slope of the
continental shelves, and with the rejuvenated streams and " fall lines "
of the tracts lying back from the coasts, a possible solution of the
common problem may be found in the habitual mode of behavior of
the continental borders.
526 GEOLOGY.
The Behavior of the Continental Borders.
We conceive the continental borders to have been affected in their
own special and peculiar way by (1) body-deformations of the globe,
(2) movements of the outer shell, and (3) movements of the sedi-
ments. With these were combined cooperative actions on the part
of the sea and of the land-drainage.
(1) The effects of body-deformation. — If the body-deformations con-
sisted, as we have supposed, of a downward movement of the ocean-
basins and a relative upward movement of the land, it was obviously
at the borders of the continent that the transition from the one to
the other took place, and hence they were the tracts in which warping
was specially felt. The basin sectors are thought not only to have sunk
relatively more, but to have crowded somewhat upon the land sectors,
and hence at their junction the sea-bottom tended to sink, and at the '
same time to push under the land, while the latter tended to rise rela-
tively, and perhaps even to spread above toward the ocean basin.
In normal cases, this tended (1) to depress the outer border of the
continental shelf, which may be supposed to have been built out upon
the border of the sea-basin by progressive sedimentation, and (2) to
submerge the stream-channels there, while (3) the region back from
the coast was warped upwards, the streams being thereby rejuvenated
and the conditions provided for the formation of the rapids of the
infra-coastal tracts.
(2) The movement of the outer shell. — If the view that an outer shell
three or four miles thick shears over the inner body of the earth be
correct, it will be readily seen that if the shell is thrust landward over
the newly deformed surface of the inner body, the continental shelf
would probably be pushed up the landward slope and so caused to
emerge obliquely from the sea, the extent of the emergence being depend-
ent on the extent of the lateral thrust, and the degree of inclination
of the shear-plane beneath. The shell must move enough, taking
the globe as a whole, to give rise to the mountain folds and the over-
thrust faults of the several periods of deformation, and this was con-
siderable, even on the most conservative estimate. Just how this motion
was distributed over the globe is uncertain; but the more the evidence
is studied, the more the conviction grows that the movement was very
general, and not necessarily confined to particular basins and con-
THE HUMAN OR PRESENT PERIOD. 527
tinents. A very wide-spread movement that concentrated the folding
along a few lines seems best to accord with the observed results, and
to involve the least shrinkage, although it involves the most shear.
But however distributed, if all the crustal wrinkling that took place
in the late Tertiary is to be accounted for by lateral movement of the
outer shell, its amount cannot have been inconsiderable, and the thrust
of the shell up the bordering incline of the sub-shell body of the
continents, must have been competent to carry a zone of the sub-
merged portions of the shell obliquely out of the water, and permit
erosion to channel its surface.
The reverse movement of the shell — The squeezing-up of the con-
tinents by the lateral crowding of the heavier sub- oceanic sectors
increased the difference in height between the continental surfaces
and the bottoms of the ocean basins, and hence increased the ten-
dency of the continental mass to creep laterally. So, also, the push-
ing of the shell up upon the more elevated continents, and the bowing
of it up in wrinkles on their borders, furnished the conditions for a
slow reverse movement. It is therefore reasoned that, following the
great deformative movements, there would have been a much slower,
glacier-like creep, both of the under-body of the continental platform
and of the superficial shell, whose movement was facilitated by the
supposed shearing zone between them. The movement of the shell
is presumed to have been much the greater, because its previous move-
ment and its distortion had been much more considerable, and because
whatever movement took place in the mass below would carry the
shell with it, while the independent motion of the shell would be added
to this. The reversed movement of the shell, at the borders of the
continent, would carry the surface next the coasts, now affected by
valleys, down the slope, and submerge it. The body of the earth,
meanwhile, had undergone little change besides shrinkage.
(3) The movement of sediments on the continental edges. — The sedi-
ments of the late periods are generally soft. There is good reason
to suppose that the muds and sands which chiefly formed the sedi-
ments built out at the edge of the continental shelves usually remained
incoherent for long periods, except where there were special cementing
agencies. Now the attitude of these was changed by the deformative
movementboih of the earth-body and of the shell, and in so far as they
were pushed above the sea-level, their weight was -increased some 70%.
528 GEOLOGY.
These changes of slope and of gravity obviously tended to cause these
soft beds to creep back toward the abysmal basin. This tendency
may well have been greatest at the edge of the continental shelf, where
the newer and softer beds may naturally have been thickest. This
creep may therefore have carried the outer ends of the channels pre-
viously formed, down to depths much below the relative horizons
at which they were eroded. Adjacent to the deep channels off the
mouths of the Congo, the Indus, and the Ganges, the edge of the lower
part of the continental shelves is observed to be somewhat protrusive.
This may, of course, be due to greater building-out at these points;
but the fact is at least consistent with the conception here entertained
and the contours are observed to be spread apart on the base of the
slope, instead of being crowded together as might be expected from
normal delta-building.
Cooperative water-displacement. — The basal deformative move-
ment, by deepening and extending the great basins, tended to draw
down the waters on the borders of the continents and hence aided in
the emergence. The postulated reversed movement of the shell and
the continental platforms tended in the opposite direction and aided
in the subsequent advance of the sea on the continental border. So,
too, the accelerated stream-erosion resulting from the increased pro-
trusion of the land tended slowly to lift the sea-level by the transfer
of sediment from land to sea.
Tidal cooperation. — Under any hypothesis it seems remarkable
that river-channels could be submerged without being filled in the
process, for the rivers must have been carrying detritus, and coastwise
currents must have swept drift into the channels. River waters can
scarcely be supposed to have been very efficient in erosion after they
reached the coast, for they were fresh and relatively light, and should
have spread out on the surface of the salt waters. The efficient agent
in the case was probably the tides. Their entrance and exit, par-
ticularly where the river-mouth broadened to an estuary, as it was
likely to do at the beginning of a submergence after a period of active
erosion, doubtless scoured the channel, and not improbably enlarged
and deepened it where the coast configuration was favorable. This
was not improbably true of some of the channels at all subsequent
stages of submergence, where they were favorably situated relative
to tidal movements, and such channels may owe not a little of their
THE HUMAN OR PRESENT PERIOD. 529
breadth and depth to this abetting action of the tides. Particularly
may this be true of channels at the outer edge of the continental shelf,
where the abysmal slope joins the more nearly horizontal surface of
the shelf. We do not find that the subject has been made one of direct
investigation, but the following data bear upon it. The speed of the
main Atlantic tide is estimated at 520 miles per hour. Computation
indicates that on the outer border of the continental shelf the speed
is normally about 100 miles an hour. In other words, in passing from
the deep ocean across the sloping shelf to the shallow water above the
shelf, the velocity is reduced 75%, and a portion of the energy is neces-
sarily converted into a wave of translation with erosive power.
It seems therefore not improbable that the trenches in the outer
edge of the continental shelf, and on the abysmal slope, are scoured
to greater depths and widths, and extended beyond their original
limits, by the tides. Such action might apparently be assigned to
any part of the abysmal slope on which the retardation of the tidal
wave was sufficient to give rise to a wave of translation. This is con-
sistent with the fact that the valleys on the abysmal slopes are broad,
and have gradients much higher than those appropriate to river-valleys
of like breadth.
If the foregoing conceptions of the behavior of the continental
borders are valid, it is not difficult to understand why the theoretical
fringe of sediments is so poorly represented above the sea-level, for
it has been borne down and thrust landward by each general defor-
mation, and has crept outward and downward with each relaxation.
The whole series is to be regarded as present in the continental shelf
and the coast-border tract, but as largely concealed by this combina-
tion of disturbing processes. When the great depth of the ocean-
basins at the edge of the continental shelf is considered, it is obvious
that the volume of sediment required to build the shelf seaward is
large in proportion to the extension of the shelf, and hence the fringing
zone is not very broad.
If the very general prevalence of harbors and inlets on the con-
tinental coasts is due to the foregoing combination of agencies, its
importance to commerce is difficult of over-estimation.
Cooperative agency of the ice-sheets. — In the glaciated regions,
especially such as had much relief, like Scandinavia, Greenland, and
British Columbia, the ice itself, by its pressure and its own lateral move-
530 GEOLOGY.
merit, must have aided the shear of the crustal shell beneath it. This
may be among the reasons why fjords are so prevalent in these regions.
THE LIFE OF THE HUMAN PERIOD.
In the seas, and on the land in the tropics, the life of the Pleisto-
cene appears to have passed by imperceptible gradations into that
of the present period. In the higher latitudes, the transition was
marked by two exceptional features, the re-peopling of the lands laid
waste by the ice-incursions, and the invasion of the human race. We
say invasion of the human race advisedly, for whatever may be true
in the low latitudes, where the race perhaps came into its peculiar
function gradually, in the higher latitudes the apparition of man took
on the aspect of an invasion; indeed, from the point of view of other
living creatures, it came as an irresistible inundation. Thus far
man's dominance has been most pronouncedly a mid-latitude move-
ment, with less pronounced potency in the very high and the very
low latitudes, but even these latitudes are not likely long to escape
the overwhelming supremacy of the new dynasty.
The re-peopling of the glaciated areas. — The re-peopling of the
northeastern half of North America by plants and animals after the
retreat of the last ice-sheet was not only the greatest event of this class,
but may be studied to greater advantage than the similar event in
northwestern Europe, because of the uninterrupted thoroughfare between
low and high latitudes. Laporta has called attention to the barrier
interposed by the Mediterranean to the free re-peopling of Europe
after the ice-invasions. He notes that certain plants that abounded
in Europe before the ice-invasions, were forced across the Mediterra-
nean, or southeastward into Asia, and did not recross the barriers of
water and desert on the resumption of a congenial climate in Europe.
No such barrier intervened in North America. There was, however,
an ill-defined climatic barrier between the arid plain region of the
southwest and the humid forest region of the southeast. There is abun-
dant evidence that open plains and arid climates had developed in
the western region in middle latitudes in the late Tertiary periods,
and that these were retained, with modifications and perhaps brief inter-
ruptions, throughout the glacial period and have become a present
inheritance. Among these evidences are the repeated drying-up of
THE HUMAN OR PRESENT PERIOD. 531
Lakes Bonneville and Lahontan, the distinctively arid topographies
of the west — the mesas, buttes, and canyons that only an arid environ-
ment can develop — the evolution of the xerophytic floras that have
been transmitted to the present stage, and the special faunas adapted
to and dependent on these xerophytic floras. The aridity that gave
rise to these physiographic and biologic evolutions probably had its
center in the zone of descending atmospheric currents which should
normally have lain near the thirtieth degree of latitude, but which,
in this hemisphere, is now, and probably was then, shifted to the north-
ward by the configuration of the great bodies of land and water. The
pre-glacial arid tracts seem to have had a distribution in the western part
of our continent not unlike that of to-day, while the eastern half of
the continent was then, as now, more moist, and covered with forests
rather than herbaceous vegetation. With the invasion of the ice of the
glacial period, the floras and faunas were forced southward, as described
in the story of that period, but differentially in the two sections. In the
west, the northern life was driven by ice behind, hemmed in by mountain
and other barriers at the sides, and resisted by arid tracts in front.
The arid tracts were themselves forced to retire in some measure, but
the lateral restraint ofbiotic migration became increasingly formidable
as glaciers gathered on the mountain heights and occupied the passes.
As the trends of the mountains were mainly north and south, they
demarked a series of meridional tracts which directed the life migra-
tions. There was therefore but little of the east-and-west intermigra-
tion that might otherwise have prevailed. Even on the plains east
of the mountains, the climatic differences seem to have appreciably
restrained east and west migration.
In the eastern half of the continent, the forests and forest-life were
driven southward in the more unrestrained way already described,
but for the greater part they kept within the eastern humid tract.
Following the last ice-retreat, the life of each of these sections
moved northward, each biotic zone, arctic, subarctic, cold-temperate,
and temperate, expanding as it went. It was as though the life-zones were
elastic bodies which had been compressed to narrow limits about the
edge of the advancing ice, and then recovered their normal breadth
as the ice-pressure was withdrawn. The arctic or tundra flora and
fauna that had probably been crowded into an almost vanishing zone
fringing the ice-sheet, moved northward through about 20° of latitude,
532 GEOLOGY.
and expanded to a breadth of 600 or 700 miles in the northern part
of the continent. It spread even beyond, occupying the arctic islands
and Greenland, where not covered by perpetual ice or snow. The zone
of this arctic flora and fauna now lies mostly north of 60°. The sub-
arctic zone of stunted conifers moved about 12° northward, and expanded
into a zone some 400 to 600 miles wide. The cold-temperate belt of
deciduous and evergreen trees moved a less distance, but expanded
almost equally, while the warm-temperate flora spread itself over the
territory abandoned by the last. With each of these vegetal zones
went the appropriate fauna. The musk-ox, whose remains have been
found skirting the glaciated area in Pennsylvania, West Virginia,
Ohio, Kentucky, Indian Territory, Missouri, and Iowa,1 has since
retired to the extreme arctic regions. The reindeer, which had a
similar distribution about the ice-edge, made a similar but less extreme
migration and still occupies the barrens of the northern border of the
continent; while the fur-clothed animals distributed themselves through
the three northerly zones, most notably the sub-arctic zone of the
conifers.2
The westward spread of these floras and faunas of the southeastern
regions seems to have been meager, and individual rather than general.
On the whole, the southwestern arid and prairie floras and faunas
seem to have had the better of the contest with the forest forms, and
to have spread eastward in the mid-latitudes at the expense of the
southeastern group; at least arboreous vegetation is found appreci-
ably farther west in interglacial deposits than on the present surface.
This does not seem to be equally true in the higher latitudes, where
the trees of the eastern group are distributed far to the northwest.
Intermigration between the floras of the east, the west, and north-
eastern Asia, seems to have been less restrained in this northern region,
doubtless because the climate was there less differentiated into moist
and arid portions.3
The arid and semi-arid floras and faunas of. the southwest seem
1 Hay's Catalogue of Fossil Vertebrates in North America, Bull. 179, U. S. Geol.
Surv., 1902.
2 Some of these and other features are suggestively discussed by C. C. Adams,
The Post-Glacial Dispersal of the North American Biota, Biol. Bull., Vol. IX, 1905,
pp. 53-71.
3 Adams, loc. cit.
THE HUMAN OR PRESENT PERIOD. 533
to have been quite successful in pushing the more boreal and arboreous
forms to the northward, or in forcing them to ascend the mountains;
but the movement was less sweeping and more complicated than that
of the east, because of topographic interference and the restraints of
the lingering mountain glaciation.
In this re-dispersion of the North American faunas and floras there
is a world of suggestive detail of which only a small part has been
worked out into clear definition. From the viewpoint of investiga-
tion, it is a rich and almost virgin soil, forming the turn-row, as it
were, between the more cultivated fields of the geologic and biologic
sciences.
The rate of re-distribution. — Most of the plants were so well pro-
vided with means of dispersion by winds, birds, or other agencies,
that they doubtless followed the retreat of the ice nearly as fast as
climatic conditions permitted, and the abandoned ground was thus
promptly clothed with such vegetation. But certain forms were not
provided with these devices, and their relatively slow rates of migra-
tion furnish an independent mode of estimating the time since the
ice began to retreat. That which we have really to estimate is not
the least time in which given plants could migrate the required dis-
tances, but the time normally occupied in the migration of an asso-
ciated group of plants, or a plant-society, some of which were slow
migrants; for the plants are now grouped according to what seem to
be their natural relations. They are not sporadically mixed as if
they were in process of individual migration independently, each at
its own pace. This group-migration is, however, difficult to deal
with, and cannot here be discussed. To illustrate studies on indi-
vidual migration, the walnut family is one of the most suitable, for
walnuts and butternuts are so unwieldy as to be habitually carried
but limited distances and buried by nut-eating animals, while the
bitter hickory-nuts (pig-nuts) can scarcely be presumed to have been
purposely transported and planted by the aborigines. There is little
reason in any case to think that transplantation was practiced by the
pre-Caucasian peoples of the eastern wooded regions, or that acci-
dental transportation by them was an appreciable factor in the dis-
persal of the plants, for if it had been, the plani>-grouping should betray
it. But the distribution of the edible hickory-nuts is not, so far as
we can learn, more extensive than that of the inedible species, and
534 GEOLOGY.
each has its own appropriate grouping in plant society, and neither
has a grouping that seems to have any relation to the homes of the
aborigines.
Aside from the spreading due to the outward growth of the limbs of
the parent-tree and the slight aid of winds, the distribution of these
trees seems to be chiefly dependent on squirrels, which have the habit
of carrying the nuts short distances and burying them for future use.
Now if 15 years be taken as the average time at which a seedling under
native conditions comes into bearing, and if a squirrel is always pres-
ent to carry the first-borne nuts an average distance of 75 feet for
burial, and always in the right direction, and always neglects to recover
them, and they always grow and escape destruction, the average rate
of migration would be five feet per year, or a mile in 1000 years. At
least four species of the family are found 300 miles back from the former
ice-limit, and the migration must have been greater than this to the
amount that these trees were driven beyond the ice-border by the
severity of the glacial climate. An appreciable portion of the dis-
tance was against a rising slope where the drainage was antagonistic,
and it needs to be observed that streams, swamps, wet meadows, and
other features were barriers to assistance by squirrels. Where the
drainage favored, the dispersal might obviously be much accelerated.
But if only the adverse slopes be considered, the time-estimate is larger
than those derived from the erosion of falls and other physical methods.
In the present state of knowledge, it is for each to judge for himself
whether the uncertainties of the biological method of estimate are
greater or less than are those of the physical, and what is the purport
of their combined testimony.
The Dynasty of Man.
Human dispersal. — As yet there is little geological evidence rela-
tive to the place of man's origin, or to the earliest stages of his develop-
ment. Various considerations connected with his physical nature
and his distribution seem to point to the warm zone of the eastern
hemisphere, preferably southern Asia, as the place of his appearance.
There are some grounds for the inference that the earliest develop-
ments of those qualities that especially gave him dominance were
associated with the open tracts of the sub-tropical zone, where rela-
THE HUMAN OR PRESENT PERIOD. 535
tively dry descending air-currents prevailed, rather than with the
dense forests of the equatorial belt where ascending air-currents and
excessive humidity prevailed. Subsequent history, as well as the
nature of the case, teach us that extreme desert conditions and excess-
ive heights are prohibitive, that semi-arid conditions of varying and
precarious intensities lead to nomadic habits, sparse distribution, and
limited social and civic evolution; while well-watered plains and fer-
tile valleys, under congenial skies, invite fixed habitation and the
development of stable civil and social institutions. Excessive humidity
and dense forests, on the other hand, tend to limitation and repression,
in a primitive people, as does also extreme ruggedness of surface.
Ascending atmospheric currents, with low barometer, high tempera-
ture, air-saturation, excessive precipitation, and lowering skies tend
to physical and intellectual lassitude and inactivity. Descending
atmospheric currents, high barometer, dry air, cool temperature, and
clear skies tend to physical and intellectual activity. In a primitive
state, before the control of accessory agencies was adequately acquired^
it is presumed that a warm climate was more helpful than a severe
one. From these considerations and from historical evidence arises
the presumption that the primitive centers of virile evolution and radia-
tion of the race lay somewhere in the open or diversified country of
the warm tract of the largest of the continents, between the excesses
of aridity and humidity, expressed in the deserts on the one side, and
the dense forests on the other. From this, or from some analogous
tract in that quarter of the globe, there seem to have been four great
divergent movements. These were complicated by reverse move-
ments, cross-migrations, and various anomalies, but only the dominant
features can be mentioned here, and these but briefly.
(1) The most voluminous movement seems to have been north-
eastward between the great desert and mountain tract of Central Asia
on the one hand, and the Pacific on the other, attended by diver-
gences eastward to many of the islands of the Pacific. When the
higher latitudes were reached, there followed a lateral spreading both
east and west, encircling the arctic regions, and sending a branch down
the full length of the American continent. This movement embraced
the great complex of Mongoloid races, including the Malayan and the
original American races. Previous to the disturbing events of recent
centuries, this branch had developed three notable centers of civiliza-
536 GEOLOGY.
tion, the Chinese in Asia, between the tropics and the parallel of 40°
N. Lat., and between the desert on the west and the sea on the east;
the Mexican in North America, between similar latitudes and in a
similar atmospheric environment; and the Peruvian of South America,
in equivalent physiographic surroundings. From these more advanced
centers of evolution there was a gradation in all directions, and
through various stages of partial civilization, to nomadic tribes, scat-
tered hunting-bands and isolated families of limited attainments.
(2) A second and much inferior movement to the southeast, reach-
ing into the southern hemisphere, gave rise to the Australioid and
associated races which have thus far failed to rise to the higher civiliza-
tions, or to develop notable power.
(3) To a third movement to the southwest is assigned the peopling
of Africa south of the Sahara with the negroid and associated races,
which have had a voluminous but not powerful development.
(4) The fourth movement was northwestward across or around
barriers of desert and mountain, to Western Asia, Europe, and North
Africa, and gave rise to the most virile and progressive branches
of the human family, the Xanthochroic (fair-white) and the Melano-
chroic (dark-white) races of Huxley's classification. The more or less
decayed trunks of these branches still remain in Western Asia. Three
chief passageways across the barriers seem to have been utilized in
this movement, and in these passageways the most notable of the
early civilizations developed, in transit as it were, and lingered for
long periods. These passageways were (1) the Red-Sea-Nile-valley
avenue, in which the dark- white and the Ethiopian races mingled, (2) the
Euphrates valley, the central avenue of the Semitic races, and (3) the
intermontane tracts of the Iranian plateau, the probable pathway of
the ancestral Aryan races, and quite certainly the pathway of the
later backward migration of the Aryans that gave the Brahminical
elements to India's early civilization.
Ignoring the feeble Australian movement, the three great diver-
gencies in the Old World were suggestively related to the physiographic
features of the region, particularly to the great desert tract that stretches
from the Sahara to the Gobi, having the Ethiopians on the south, the
Mongoloids on the southeast and east, and the Caucasians on the north
and west. While inferences from physiographic relations may easily
be pushed too far, there is little doubt that they were very influential
THE HUMAN OR PRESENT PERIOD. 537
in the early evolution and distribution of the human race. Relation-
ship to the open, semi-arid, or mildly humid plains and fertile valleys
that bordered on the desert barriers, was probably influential in lead-
ing to that control of the plant and animal kingdom that has made
man the most influential of all biological agencies. Powell and others
hold that agriculture owed its chief early evolution to arid conditions
which induced man to irrigate and cultivate the plants necessary for
his sustenance, and tended to fix his abode in the watered tracts. It
is urged that the watering and slight culture of chosen plants in an
arid tract was a less formidable task to ill-equipped primitive peoples,
than the subjugation of competitive plants in a humid region. How-
ever this may be, there are various reasons why the open lands of
semi-arid or mildly humid regions, with their varied floras and faunas
and their active expansive life, with its sharp competitions in fleetness,
alertness, and sagacity, and its occasional crises of drought and storm,
should have fostered a favorable evolution in primitive man. The
cereals he learned to cultivate were chiefly members of the grass family
that grew natively on the plains, and the animals he domesticated
were largely also those of the plains. To us it seems also significant
that the centers of early civilization were all regions of relatively high
barometer, of descending air-currents, and of semi-arid or mildly humid
atmospheric conditions, all of which seem to be more favorable to
activity of mind and body than prevailing low barometer, ascending
air-currents, and humidity.
The physiographic associations of the progressive stages of civiliza-
tion of the white races are suggestive. The most ancient recorded
civilizations lay in the valleys of the Nile and Euphrates on fertile
plains, but bounded by inhospitable deserts or mountain tracts, and
in latitudes near 30° N. The somewhat later civilizations of Assyria,
Palestine, and Phoenicia lay a few degrees farther north under simi-
lar conditions, but with sea-contact, another of the expansive influ-
ences, added in the case of Phoenicia. The succeeding civilization of
Greece lay about 5° farther north, under clear skies, pure dry air, high
barometer, and abundant sea-contact. The center of the more virile
and militant Roman civilization lay still another 5° farther north. The
later medieval and early modern civilization centered about France,
another subequal step northward, while present gravitation of power
and intellectual development is toward still more northerly latitudes.
538 GEOLOGY.
" Northward the star of empire takes its way " is quite as true as the
more familiar apothegm, and carries a more obvious causal suggestion,
that of the need of a progressively higher degree of stimulus from low
temperature, as man increased the means of his control of natural
agencies. The modern movement has also been somewhat more toward
mildly humid and forested regions, perhaps because man's superior
resources have led to the removal of their deterrent features, and have
permitted a larger utilization of their advantageous ones. It is also
a question whether, at the present stage of the development of man's
nervous organization, a somewhat less stimulative atmosphere may
not best conserve his energies, and give steadiness, persistence and
endurance to his sufficiently aggressive endeavors. The comparative
results that shall arise from the different physiographic conditions in
North America, where the same race under the same institutions is
subjected to wide ranges of barometric states, temperatures, air-move-
ments, humidity, and topography, may well be watched with interest.
The exceptionally rapid evolution of the American people, an off-
shoot of the older peoples of the Eurasian Occident, and the similarly
rapid evolution of the Japanese people, in some sense an offshoot of
the more ancient peoples of the Eurasian Orient, are to be studied
on their own special grounds.
A basal factor in all this early evolution of civilization was the
productiveness and availability of the soil. The passage from the
condition of hunters and fishers, scattered necessarily to adjust them-
selves to the distribution of game, and shifting with its changes, or
from that of simple herders in sterile tracts, roaming with the changes
of pasture, in both cases deprived of the evolutionary influences of a
fixed abode and of a permanent social and civil organization, was
essentially dependent on agriculture, and was hence largely controlled
by the permanent fertility of the soil, conjoined with suitable climatic
conditions. And so, conversely, among the agencies that have forced
the migration of centers of civilization, loss of soil or of soil-fertility,
is one of the more important. In the lower latitudes, the upland
soils are usually but the residue left by the decomposition of the under-
lying rocks which has not been removed by surface-wash. Its depth
is usually quite limited. With cultivation, wash and wind-drift are
accelerated, and unless ample preventive measures are employed, as
has not usually been the case in past history, the soils are at length
THE HUMAN OR PRESENT PERIOD. 539
swept away, and barrenness succeeds productiveness. There are areas
in the Orient, once well settled, that are now bare fields of rock on
which nothing grows except such few plants as find a foothold in the
crevices of the rock. Soils with sandy subsoils have been washed
away, leaving barren wastes, and the sands derived from the denuded
subsoil have been driven by the winds over adjacent fertile tracts,
and by burial have included these in the common waste. The explana-
tion of much of the former richness and of the present poverty of Oriental
peoples no doubt lies in this simple process. This impoverishment
of soil threatens many peoples to-day, and is in process of actual reali-
zation.
The glaciated fields are comparatively new grounds for civiliza-
tion, and the soil-factor there has a character quite its own. Near
the centers of glacial radiation, the old soils were borne away, and
new soils were not always developed in equal amount in their stead.
A reduced fertility is the result. The half-decayed rock below was
largely scraped away, and a long period must ensue before soil-genera-
tion will have become effective. These areas lie chiefly in high lati-
tudes where other factors compromise human development in its pres-
.ent state. In the regions of glacial deposition, which fortunately
include the greater and the more southerly parts of the glaciated area,
a deep sheet of comminuted rock-material, ready for easy conversion
into soil by weathering and organic action, covers great plains and
has a smoothed topography that aids in restraining its removal. In
the peripheral belt of the glaciated area in North America, for a width
of 400 or 500 miles, the subsoil of glacial flour and old soil, glacially
mixed, has an average thickness of about 100 feet. A similar state-
ment may be made of a large, though less, area in north-central Europe.
The average thickness of the residuary soils of unglaciated regions
similarly situated is about 5 feet. The twenty-fold provision for per-
manent fertility thus arising from glaciation seems likely to be a factor
of immeasurable importance in the localization of the basal industry
of mankind, and of the phases of civilization that are dependent on it.
With the evolution of the industrial arts, resources which were
neglected at first have come to play important parts in the distribu-
tion and in the activities of the race, among which are the long and
growing lists of mineral resources to which economic geology addresses
itself. Chief among these are the metallic ores, the fossil fuels, the
540 GEOLOGY.
mineral fertilizers, and the structural and ornamental materials of
stone and clay. These now control man's distribution and his aggre-
gate power, to a degree not even remotely approached a century ago,
and they are quite certain to be more influential in the future.
Distribution and activity have also recently come to be affected
by the distribution of rejuvenated streams that arose from the defor-
mations of the late Tertiary periods, and by the stream-diversions of
the glacial period, both of which have furnished sources of water-
power heretofore neglected in the main. With little doubt, such
native sources of power are to play an increasingly large part in human
affairs as time goes on and the stored fuels are exhausted.
With the increasing complexity of human activities, the localiza-
tion of the race will more and more depend on combinations of resources
and of conditions, and less upon single factors; but it is difficult to see
beyond the day when persistent fertility of the soil, under favorable
climatic conditions, coordinated with great supplies of ores, fuels, and
structural materials, will not constitute a decisive and controlling
advantage.
Provincialism giving place to cosmopolitanism. — The early history
of human dispersal was marked by pronounced provincialism. The
early peoples were much isolated from one another by distance and
by natural barriers, and they themselves often interposed artificial
barriers against free inter-communication, and hence against the pres-
ervation of a common cosmopolitan type. So long as hunting and
fishing were the dominant pursuits, a wider and wider dispersion into
small tribes was a necessary tendency, which was abetted by conflict
of interests, strifes and wars, and the sentiments and customs that
arose from these. That such artificial sources of provincialism were
more effective than the natural ones seems to be implied by the fact
that while physiological differences sufficiently marked to readily
characterize varieties were numbered by hundreds, dialects sufficiently
different to prevent free intercourse were numbered by thousands.
Provincial sentiment to-day manifests itself more conspicuously in
language than in most other respects. The tendency to provincialism,
however, has never gone so far as to divide the race into distinct
species, forever separated by infertility.
When efficient water-transportation was developed and the con-
trol of the sea was attained, a period of cosmopolitan tendency was
THE HUMAN OR PRESENT PERIOD. 541
inaugurated, and began to counteract the provincial tendency. This
has been greatly accelerated in the past few decades, supplemented
by swift land-transportation and by electric communication, and is
rapidly involving the whole race in a cosmopolitan movement. Almost
the whole world is already in daily communication, and almost all the
races are more or less habitually intermingling by travel and trade.
That this is to become more and more habitual until the whole race
shall be in constant intercommunication, is not to be questioned.
There will then have been inaugurated the most marked period of
cosmopolitanism, in all senses of the term, which the world has ever
witnessed. With this will doubtless come endless blood-mingling, and
the racial divergences of the past will be replaced by racial conver-
gences in the future. What this will ultimately mean for the race
we will not venture to predict.
Man as a geological agency. — The earlier geologists were inclined
to regard man's agency in geological progress as rather trivial, per-
haps because physiographic geology, in which his influence is chiefly
felt, was then less cultivated than marine, volcanic, and hypogeic
geology, in which he scarcely participates. But probably no pre-
vious agent in an equal period of time has so greatly influenced the
life of the land, both plant and animal, and the rate of land-degrada-
tion, as has man since the full inauguration of the present agricultural
epoch, and particularly in the last century (Vol. I, pp. 649-651).
That this influence will be increased during coming centuries seems
clearly foreshadowed. The flora is rapidly passing from that which
had been evolved by natural agencies through the long ages, to that
which man selects for cultivation or preservation, together with that
which has taken advantage of the special conditions he furnishes.
With the further progress of this movement, the native floras seem
destined to an early extinction. The same may be said of the native
faunas. The favored animals, under man's care, flourish beyond
precedent, while the rest, so far as they are within his reach, are suffer-
ing rapid declines that look toward extinction. The life of the sea
is less profoundly affected than that of the land, but even that does
not escape important modifications. The most pronounced exceptions
to man's dominance, and those that bid fair to contest his suprem-
acy longest, are found in organisms too minute to be easily con-
trolled by man, and in organisms that, quite against his wish, flourish
542 GEOLOGY.
on the conditions he furnishes. But even the accelerated evolution
of these organisms is a part of the profound biological revolution which
attends man's dominance.
Man's control has not thus far been characterized by much recog-
nition of the complicated interrelations of organisms and of the con-
sequences of disturbing the balance in the organic kingdom, and he
is reaping, and is certain to reap more abundantly, the unfortunate
fruits of ignorant and careless action. For the greater part man
has been guided by immediate considerations, and even these not
always controlled by much intelligence, while great wantonness has
attended his destruction of both plant and animal life. But a more
intelligent as well as a more sympathetic attitude is developing, and
will doubtless soon become dominant.
A new era in control and in evolutionary selection is dawning.
New varieties and races are being produced that not only depart widely
from the parent stock, but diverge in lines chosen to meet given con-
ditions, or to produce desired products. How far this may yet go
it is impossible now to predict. But it may be worth while to suggest
that some of the species man is wantonly destroying may possess capa-
bilities of mutation quite beyond present apprehension, and that m
species should be allowed to pass utterly beyond reach forever until
man shall learn more about its ulterior possibilities.
Prognostic Geology. — The long perspective of the past shouk
afford at least some suggestions of the future, but it must be con-
fessed that the most important previsions are dependent on intei
pretations of the past that have not yet emerged from the tentativ
state. A word has been said relative to a possible return of a glacis
epoch, but this is contingent on agencies that are yet matters of hypotl
esis, and no sure prediction can be offered. Question has been n
as to whether the end of the recent period of deformation has come
and a gradation into another period of quiescence and equable genis
conditions has begun ; but the answer hangs on the doctrine of periodicity
of deformation and quiescence which does not yet command univei
assent, and if it were given, there would remain the further questioi
whether the period of deformation is completed. The duration of tl
earth as a habitable globe has been a common theme of prognosis
A final refrigeration as the result of the secular cooling of a once moltei
globe has been the usual forecast, and the final doom of the race has
THE HUMAN OR PRESENT PERIOD. 543
been a favorite theme for quasi-scientific romances. But this all
hangs on the doctrine of a former molten earth, if not also more remotely
upon the doctrine of an origin from a gaseous nebula. Under the
alternative conception of a slow-grown earth, conserving its energies
and giving forth atmosphere as there is need for it, conjoined with a
more generous conception of the energies resident in the sun and the
stellar system, no narrow limit need be assigned to the habitability
of the earth. A Psychozoic era, as long as the Cenozoic or the Paleo-
zoic, or an eon as long as the cosmic and the biotic ones, may quite
as well be predicted as anything less. The forecast is at best specu-
lative, but an optimistic outlook seems to us more likely to prove
true than a pessimistic one. An immeasurably higher evolution than
that now reached, with attainments beyond present comprehension,
is a reasonable hope.
The forecast of an eon of intellectual and spiritual development
comparable in magnitude to the prolonged physical and biotic evolu-
tions lends to the total view of earth-history, past and prospective,
eminent moral satisfaction, and the thought that individual contri-
butions to the higher welfare of the race may realize the fullest fruits
of their permanent worth by continued influence through scarcely
limited ages, gives value to life and inspiration to personal endeavor.
APPENDIX.
THE following sections, from different parts of the United States,
supplement the sections already given and convey some idea of the
sequence of the known systems in widely separated areas.
545
546
APPENDIX.
SECTION IN WEST CENTRAL MASSACHUSETTS.1
Names of Formations.
Thickness
in Feet.
Characteristics.
) 1 Devo- (
Ordovician. Silurian. ( nian. ( Triassic.
Chicopee shale.
200?
Sandy carbonaceous shale.
Granby tuff.
580
Agglomerate of diabase, interstratified with
sandstones.
Blackrock diabase.
Volcanic cones and dikes of diabase.
Longmeadow sand-
stone.
1000
Feldspathic, ferruginous sandstone.
Sugarloaf arkose.
4660
Feldspathic sandstone and conglomerate (west
side of Triassic trough).
Mount Toby con-
glomerate.
-» Unconformity ^^^
Bernardston series.
- Unconformity-^ — ~
Leyden argillite.
)
1950
300
Basal conglomerate of slate and crystalline
rocks (eastern side of Triassic trough).
Dark mica-schist, with several beds of amphi-
bolite, over quartzite (650 feet) containing a
bed of highly crystalline limestone (20 ? feet)
Black fissile slate.
j;al:i 5
'" r " '• •• ! C; •• •
Conway schist.
Amherst schist.
Brinfield fibrolite-
schist.
' : •' L'i 1
5000?
The Conway schist is a fine-grained, carbona-
ceous, muscovite-schist, much contorted. The
Amherst schist is a rusty mica-gneiss, im-
pregnated with granite. The Conway, Am-
herst, and Brinfield schists are perhaps geo-
graphic variations of the same formation.
The granite was probably erupted during the
Carboniferous period.
t Goshen schist.
*- Unconformity -^^^
Hawley schist.
2000?
2000?
Dark, flaggy schist with interbedded gneiss.
Green sericite-chlorite schist, with beds of am-
phibolite and manganese silicates.
Savoy schist.
5000?
Chloritic, quartzose sericite-schist, with beds
of amphibolite, grading into feldspathic mica-
schist. Many intrusions of granite.
Chester amphibolite.
3000?
Epidotic, hornblende-schist, with beds of mag-
netite and emery near top; contains beds of
pyroxene rock, enstatite rock, and dolomite;
often replaced by serpentine and steatite.
Rowe schist.
4000?
Quartzose sericite-schist; sometimes indistin-
guishable from the Hoosic schist. Some
granite.
Hoosic schist.
1500
Feldspathic mica-schist, with granite.
1 Emerson, Hoi yoke (Mass.-Conn.) folio, U. S. Geol. Surv. In the folio, the beds here classed
as Triassic are called Jura-Trias, the Ordovician and Silurian are classed together under the name
Silurian, and the Proterozoic is called Algonkian.
APPENDIX.
SECTION IN WEST CENTRAL MASSACHUSETTS — Continued.
547
Names of Formations.
Thickness
in Feet.
Characteristics.
II
., 8-t
*- Unconformity-^^ —
{
\ Becket gneiss.
2000?
White biotite gneiss, locally grading into con-
glomerate.
~~v^~v^
- Unconformity^
-x ™x ^
0 O
I's
(Washington gneiss.
Base not exposed.
2000?
Rusty biotite-gneiss.
Silurian strata much folded and metamorphosed, but not so severely as the earlier
strata. Devonian strata less folded and metamorphosed than the Silurian. Triassic
beds tilted and much faulted, though little folded or metamorphosed.
548
APPENDIX.
SECTION IN EASTERN TENNESSEE.*
Names of Formations.
Thickness
in Feet.
.- Characteristics.
IIT.-G. Ordovician. Silu- Devonian. Mississippian. Pennsylvanian.
r Summit removed by
erosion.
Anderson sandstone.
1000 +
Interbedded with sandy and argillaceous
shales and thin coal-beds.
Scott shale.
500-650
Argillaceous and sandy, with beds of sand-
stone and thin coal-seams.
Wartburg sandstone.
500-600
Argillaceous shale, and coal-beds, interbedded.
Briceville shale.
250-650
Black, bluish-gray, and gray; also thin beds of
sandy shale, sandstone, and thick coal-beds.
Lee conglomerate.
Possible Unconformity
Pennington shale.
500-1500
160-400
Massive sandstone and conglomerate, thin
shale-beds, and coal-seams.
Calcareous shale, sandstone, and limestone.
Newman limestone.
650-700
Massive, blue, with shale-beds.
Massive beds of chert and cherty limestone.
Grainger shale.
1200
3. Red and yellow sandy shale.
2. Massive white sandstone.
1. Greenish and bluish-gray; arenaceous.
Chattanooga black
shale.
30-50
Black, calcareous.
a < Clinch sandstone.
6
Present only in one small area.
' Bays sandstone.
300-1100
Red, calcareous.
Sevier shale.
500-600
Light-blue calcareous shale.
200-400
Bluish-gray and red calcareous sandstone and
shale.
500-600
Light-blue calcareous slate.
500-650
Bluish-gray and gray calcareous sandstone and
shale.
500-750
Light-blue, calcareous.
Tellico sandstone.
800-900
Bluish-gray and gray, calcareous, with some
shale.
Athens shale.
1000-1200
Light-blue and black; calcareous.
Chickamauga limestone
0-50
Gray, argillaceous.
Knox dolomite.
3500
White, gray, light- and dark-blue, with chert.
i Keith, U. S. Geol. Surv. Formations above the base of the Mississippian are taken from the
Briceville (Tenn.) folio; the remainder from the Knoxville (Tenn.-N. C.) folio. The Ordovician
and Silurian formations are classed as Silurian in these folios.
APPENDIX.
SECTION IN EASTERN TENNESSEE — Continued.
549
Names of Formations
Thickness
in Feet.
Characteristics.
Lower Cambrian. Middle Cambrian.
Nolichucky shale.
450-550
Yellow and brown, calcareous, with limestone-
beds.
Maryville limestone.
350-500
Massive, dark-blue.
Rogersville shale.
180-220
Bright-green, with a limestone-bed.
^ Rutledge limestone.
350-450
Massive, dark-blue.
Rome formation.
750-950
Red, green, yellow, and brown shales, some-
times sandy and red, white and brown
sandstones, and sandy shales.
Beaver limestone.
300
Massive, blue.
A pi son shale.
200
Green.
900 +
Bright-red, green, and brown; sandy.
Discontinuity. 1
Hesse sandstone.
500 +
Fine, white, massive.
Murray shale.
300
Grayish-blue, sandy.
Nebo sandstone.
500
Massive, white.
Nichols shale.
550-800
Grayish-blue, sandy.
Cochran formation.
600-900
Massive white sandstone.
0-100
Red sandstone, gray sandy shale.
500-700
Coarse conglomerate; quartz, and
pebbles.
feldspai
Sandsuck shale.
w Base not exposed.
1000 +
Grayish-blue.
Strata much folded and faulted.
1 See note on preceding page.
550 APPENDIX.
SECTION IN EASTERN WEST VIRGINIA AND WESTERN VIRGINIA. J
Names of Formations.
Thickness
in Feet.
Characteristics.
L c 3 M. & Ord. Silurian. Devonian. Mississippian. ( Pennsylvanian.
Summit removed.
Braxton formation.
700 +
Red and yellow shale, gray and brown shaly
sandstone, and coal-seams.
Upshur sandstone.
350-500
White and brown, with conglomerate, shale
and coal.
Pugh formation.
300-450
Brown and white sandstone, and blue and
black clay; thin coal-seams.
Pickens sandstone.
^- Unconformity^
Canaan formation.
400-500
1000-1300
Brown, gray, and white; some conglomerate,
and dark shale with coal.
2. Red shales and brown sandstones.
1 . Thin limestone.
Includes some red shales.
Coarse and hard, partly conglomeratic.
Sandstones and shales, mainly red.
Gray and buff sandstones, with shales.
Greenbrier limestone.
350-400
t Pocono sandstone.
70-90
Hampshire formation.
1500-1800
Jennings formation.
3000-3800
Romney shale.
"*- Unconformity^^
Monterey sandstone.
1000-1300
50-200
Black and fissile below, lighter and more sandy
above; thin bed of limestone at base.
Calcareous, weathers buff.
Lewiston limestone.
550-1050
Thin-bedded, impure limestone, with shale at
base; thin flaggy limestone, massive lime-
stone, and cherty limestone in order, above.
Quartzite at base at the east; shale with
thin beds of sandstone, limestone, and iron
ore above, and gray sandstone at top.
Red, mainly flaggy.
White and gray.
. ,
Brownish-red sandstones and red shales.
'
Gray shale; sandy beds near top.
,
3. Light gray, fossil if erous.
2. Darker gray, cherty.
1. Partly magnesian.
Rockwood formation.
100-900
Cacapon sandstone.
100-630
Tuscarora quartzite.
50-300
Juniata formation.
205-1250
Martinsburg shale.
800-1800
f Shenandoah 1 i m e -
\ stone.
\ Base not exposed.
2400 +
Carboniferous strata nearly horizontal; earlier beds folded, but not much faulted.
1 The section above the Canaan formation is taken from the Buckhannon (W. Va.) folio, the
remainder from the Monterey (Va.-W. Va.) folio. Darton (Monterey) and Taff and Brooks (Buck-
hannon) U. S. Geol. Surv. In these folios the Ordovician and Silurian are classed as Silurian.
2 Middle and Upper Cambrian. 3 Lower Cambrian.
APPENDIX.
551
SECTION IN NORTHEAST ALABAMA AND NORTHWEST GEORGIA.1
Names of Formations.
Thickness
in Feet.
Characteristics.
Upper Ordovi- Silurian. / Devonian. Mississippian. Pennsylvanian.
Summit removed by
erosion.
Walden sandstone.
500 ±
Coarse sandstone and sandy shale; beds of
coal and fire-clay.
Lookout sandstone.
.
60-570
2. Conglomerate with massive sandstone.
1. Sandy shale with coal and fire-clay.
Bangor limestone.
300
Blue, crinoidal, cherty limestone.
Oxmoor sandstone.
•^ Unconformity-—
Floyd shale.
50-550
2000 +
White and brown sandstone and conglomerate.
Black, carbonaceous, with occasional beds of
crinoidal limestone.
Fort Payne chert.
20-200
Bedded chert and limestone.
Chattanooga shale.
0-22
Black, carbonaceous.
Armuchee chert.
-^ Unconformity •>-
Rockwood formation.
r
0-40
1000-1500
Rusty, sandy chert.
White, brown, and purple sandstone and
sandy shale, with beds of red fossiliferous
hematite.
; 1
8 ! Chickamauga lime-
stone.
700-1500
Blue flaggy limestone, sometimes purple and
mottled, earthy towards the top. Heavy
chert conglomerate at the base in places.
ill
§.2 •{ Knox dolomite.
^ I
1500-4000
Dolomite, white, gray, or light-blue, generally
granular and massive; containing nodules
and layers of chert.
g , • f Conasauga forma-
9 S i 1 tion.
•^ d 5 1 ^ase not' exP°sed-
1000 +
2. Greenish siliceous shale and micaceous
sandstone.
1. Olive clay shale.
Strata much folded and faulted.
1 The two youngest formations in this section are taken from the Gadsden (Ala.) folio, the others
from the Rome (Ga.-Ala.) folio. Hayes, U. S. Geol. Surv. In the folio, Ordovician and Silurian
are classed together under the name Silurian.
552
APPENDIX.
SECTION IN CENTRAL TENNESSEE.1
Names of Formations.
Thickness
in Feet.
Characteristics.
Summit removed by
A
erosion.
Gray and blue, thick-bedded, fossiliferous;
.1
3 St. Louis limestone.
250
generally very cherty; basal part porous.
$ '
^ -^^ Unconformity - — -
— — — ^ _^_ — ^ ^^ ^-^^,
3
Tullahoma forma-
tion.
0-250
Greenish clay shale at bottom, cherty shale
and limestone above.
•^s-X-N
^^ Unconformity ^-^-^
,
-~^ -^—^^ ^^__^_
4
a f
Black and carbonaceous, generally with phos-
I"
3 1 Chattanooga shale.
3 I
0-10
phatic band at base, and glauconitic green
shale, with phosphatic nodules at the top.
— -x--~
*-~ Unconformity —-——
_^,
-^ — ~_~^. ^^ ^~^.
i
g-
« < Clifton limestone.
H I
0-60
Even-bedded, dense, light-gray or bluish; oc-
casionally shaly below.
'V'x.
~^- Unconformity ^^~^
— — ~_^
— — ~ — — - — — ., •+*'~~. ^^^^^^^-_-^-^^,
'
Soft green- and chocolate-colored shales, and
Fern vale formation.
0-40
red, ferruginous, crystalline limestone; occa-
sionally conglomeratic and phosphatic.
^^-^^ u nconformity~~- — ^^
*"" *^~*^~^~*~^>~n~i~~^-
— ~^-*_-— ^-- -^ -^— ^—^_ ^-^,->^- - -~^—_— _^^^^- -- _--._-- s ^ ^.
In eastern part of quadrangle, knotty, earthy
limestone at top, with shaly and highly fos-
Leipers formation.
0-100
siliferous beds below; in western part, granu-
lar, crystalline limestone, the more granular
portions highly phosphatic.
~-^~~ Unconformity^^^-
^^
^-~ — ~~ ^-^ ^-^-^-^. ^^
Shales and knotty limestones, usually under-
lain by heavy-bedded subcrystalline lime-
Catheys formation.
0-100
stone, and overlain by fine-grained blue or
earthy limestones separated by thin seams of
shale. Basal part includes some granular
I
phosphatic layers.
o
'I-
Granular, crystalline, laminated, phosphatic
-i
0
Bigby limestone.
30-100
limestones ; upper part often shaly or arena-
ceous, lower part has some shale but is never
sandy.
Even-bedded, alternating, thin layers of argil-
laceous or siliceous limestone and shale in
Hermitage formation.
40-70
lower third, and siliceous subgranular lime-
stone, more or less phosphatic, in middle
and upper parts.
^^~ Unconformity^-^
, ^-
v — ^~ - — —
Carters limestone.
40-60
Heavy-bedded, fine-grained, white or light-
blue; often contains chert and silicified
fossils.
Lebanon limestone.
70-100
Thin-bedded, often shaly, bluish or dove-
colored.
Base not exposed.
Strata somewhat warped but nearly horizontal.
1 Hayes and Ulrich, Columbia (Tenn.) folio, U. S. Geol. Surv.
APPENDIX.
553
SECTION FOR SOUTHERN MICHIGAN.'
Names of Formations.
Thickness
in Feet.
Characteristics.
1 Ordovician. Silurian. Devonian. Misslssippian. / Pennsylvanian. S
Glacial drift, etc.
— Unconformity —-
Woodville sandstone.
•^- Unconformity^
Jackson Coal (or Sagi-
naw) series.
Possible unconformity
Parma? sandstone.
«> Unconformity^
Grand Rapids series.
0-600
304 +
47 ±
Gravel, sand, and clay.
Gray sandstone grading into blue shale ; layers
of fire-clay.
Sandy shales of various colors, with layers of
fire-clay and beds of coal; charged with
iron pyrites; principal coal horizon of Michi-
gan.
0-200
305 ±
Porous and saturated with brine.
Limestones, underlain or replaced by shales
and dolomite with gypsum.
Marshall sandstone.
50 ±
Contains brine.
Cold water shales.
667-1000 +
Blue arenaceous shales, with seams of fine-
grained sandstone. Balls of kidney iron
"ore" in some layers.
Richmondville or
Berea sandstone.
65
Contains brine in large amounts; signs of oil
and gas.
Antrim (St. Clair)
Black shales.
145-300
Often bituminous.
Traverse group.
100-600
Some limestone in reefs, some dolomite, much
blue argillaceous limestone, shales; signs of
oil and gas.
Dundee limestone.
40-160
Light-colored limestone, containing mineral
water; some oil and gas.
Monroe formation.
650-2000
Dolomite, with rock salt, gypsum, and glass-
sand; brines and mineral waters.
. Niagara formation.
350 +
White dolomites and limestone.
' Lorraine and Utica
formations.
600
Blue and black shales, with some limestone.
t Trenton limestone.
?
Dolomite and limestone, somewhat oil-bearing.
1 Lane, Geol. Surv. of Mich., Vol. V, Plate LXXIII, adjusted to nomenclature of Geological Map of
Michigan in Geol. Surv. of Mich., Vol. VIII. Section based largely on well-borings at Jackson and
Monroe.
554
APPENDIX
GENERALIZED SECTION FOR OHIO.
Names of Formations.
Thickness
in Feet.
Characteristics.
Silurian. Devonian; Mississippian. Pennsylvanian. Permian.)
- Unconformity —
Dunkard formation.
.
525 ±
Sandstone, generally massive, shales, lime-
stone, and thin coal-seams; non-marine at
least in part.
" Monongahela forma-
tion.
200-250
Shales, limestones, and sandstones, with im-
portant beds of coal.
Conemaugh formation.
400-500
Upper part mainly shales; lower part sand-
stone, with some shale and limestone.
Allegheny formation.
165-300
Shales, limestones, and sandstones, with im-
portant coal-seams.
O Waverly series. g \ %
2. . B r-H&> e*
tsville conglomer-
te.
Unconformity »-"•
cville limestone.
250 ±
25 ±
Light-colored sandstones and conglomerates,
with some shale and a few coal-seams.
Fossiliferous limestone, often brecc'ated.
Logan group.
100-150
Sandstone, massive conglomerate, and shale.
Black Hand con-
glomerate.
50-500
Sandstone and fine conglomerate.
Cuyahoga shale.
150-300
Light-colored, argillaceous shales, with thin
beds of sandstone. Shales characterized by
ferruginous nodules.
Sunbury shale.
5-30
Black bituminous shale.
Berea grit.
5-175
Sandstone, used for building-stone and for
grindstones; locally carries oil, gas, and brine.
Bedford shale.
50-150
Thin-bedded shales; occasional thin beds of
sandstone.
o shale.
300-2600
Mainly black or dark-brown shale.
Olentangy shale.
20-35
Blue, highly fossiliferous.
Delaware limestone.
30-40
Blue, thin-bedded.
Columbus limestone.
110
Light-colored, often containing chert masses.
Monroe formation.
50-600
Compact magnesian limestone, usually poor in
fossils.
Niagara group.
150-350
Light-colored shales at base, dolomitic lime-
stone above, and a thin sandstone bed at
top.
Clinton limestone.
10-50
Crystalline, locally replaced by iron ore.
Medina shales (?)
(Belfast bed).
50-150
Red or yellow, non-fossiliferous shales, with
local thin beds of sandstone.
1 Prosser, Jour, of Geol.
Bull. 7, 4th Ser., 1905.
Vol. XI, pp. 520, 521. Geol. Surv. of Ohio, Vols. VI and VII, and
APPENDIX
555
GENERALIZED SECTION FOR OHIO — Continued.
Names of Formations.
Thickness
in Feet.
Characteristics.
Ordovician.
Saluda beds.
20 ±
Mottled clays and thin-bedded limestones.
Richmond formation.
300 ±
Alternating beds of shale and limestone,
highly fossiliferous.
Lorraine formation.
300
Alternating beds of shale and limestone,
highly fossiliferous.
Eden (Utica) shale.
250
Black.
Trenton limestone.
130
Light to dark-blue, crystalline, massive-bedded
and fossiliferous; the most important oil
and gas horizon of the State.
Strata dip at low angles.
556
APPENDIX.
GENERALIZED SECTION FOR INDIANA.*
Names of Formations.
Thickness
in Feet.
Characteristics.
( Pennsyl- $ Permian / Quater-
bilunan. Devonian. Mississippian. t vanian. > or ( nary.
Glacial and post-
glacial deposits.
^ Unconformity —— ^
\
•| Merom sandstone.
- Unconformity ~— ^
Coal Measures.
Mansfield sandstone.
- Unconformity ~~^~^^
Kaskaskia.
0-385
60 +
300-800
Sand, clay, and gravel.
Massive sandstone.
Shales, clays, sandstones, limestones, and coal.
0-125
120
Massive.
Sandstone and limestone.
Mitchell limestone.
0-250
Massive.
Bedford Oolitic
limestone.
20-80
Excellent building-stone.
Harrodsburg lime-
stone.
60-90
Knobstone.
Rockford goniatite
limestone.
40-600
Arenaceous shales and sandstones; thin lime-
stone at base.
New Albany Black
shale.
70-120
Brown shale.
25-47
Hamilton formation.
47
Limestone and shale.
Corniferous.
5-85
Limestone and sandstone.
Lower Helderberg( ?)
formation 2
25-230
Limestone.
Waterlime forma-
tion.
65-150
Limestone.
Niagara formation.
50-450
Limestone and shale.
Clinton and Medina
formations.
0-100
Limestone, etc.
1 Blatchley and Ashley, Indiana Dept. of Geol. and Nat. Res., 22d Ann. Rep., 1897, PI. II.
2 If this is really the Helderberg formation, it should be classed as Devonian, according to the
classification here adopted.
APPENDIX.
GENERALIZED SECTION FOR INDIANA — Continued.
557
Names of Formations.
Thickness
in Feet.
Characteristics.
i
Hudson River for-
mation.
260-860
Limestones, clays, and shales.
Utica shale.
0-300
s
'i •
•e
o
&sc
HI
Galena and Trenton
limestone.
486-525
St. Peters sandstone.
150-224
Lower Magnesian
limestone.
50 +
f Potsdam sand-
•j stone.
[ Base not exposed.
1000 ±
558
APPENDIX.
GENERALIZED SECTION FOR lowA.1
1
Names of Formations.
Thickness
in Feet.
Characteristics.
0
M
&*
P c
*s~**s-
1
o3
>
1
1
g
;i
i '
i
§
i'
3
ra
QQ
X^~N^
Glacial drift.
*-• Unconformity ~~^^~
j Benton formation.
5
125
0-150
Shale, chalk, and thin-bedded limestone.
1
1 Dakota formation.
I
^ Unconformity ^-~-^
Missouri formation.
50-100
1500
Shales, sometimes calcareous; and sandstone,
sometimes concretionary. Thin bands of
lignite. Non-marine in part at least.
Mainly light-colored, calcareous shales, grading
into pure limestone ; limited amounts of bitu-
minous shales; few seams of coal of economic
importanca
Des Moines formation.
— Unconformity ~~^^
St. Louis limestone.
250-400
100
Clay-shales, often highly bituminous; sand-
stones, often in thick layers; limestones in
thin bands; important coal-beds.
Light, ash-colored limestones, and marls, with
thin beds of sandstone. Good building stone.
Osage (Augusta) for-
mation.
200-300
Buff limestone and shales, underlain by coarse-
grained encrinital limestone; basal portion
usually ferruginous; prominent chert-beds.
Kinderhook formation.
150-200
Bluish or greenish clay shales, fine-grained;
buff, compact, more or less argillaceous lime-
stones; sandstones.
Lime Creek formation.
80
Dark-colored argillaceous shales, highly fos-
siliferous, and locally calcareous.
State Quarry beds.
Sweetland Creek shales.
Unconformity-^^
Cedar Valley limestone
20-40
Light gray; good building-stone. Fish teeth.
20-40
250-300
Black and greenish; Upper Devonian fossils.
Pure to argillaceous limestone and dolomite;
sometimes massive, sometimes finely lami-
nated, frequently brecciated.
Wapsipinicon f orma-
1 1 o n . (Independ-
ence, Fayette, Dav-
enport.)
100-150
Carbonaceous shales with bands of impure con-
cretionary limestone; brecciated limestone.
Anamosa limestone.
50-75
Soft, granular, evenly bedded dolomite; white
to buff and gray; important building-stone.
Le Claire limestone.
50
Massive or heavy-bedded highly crystalline
dolomite. Upper surface undulating; cross-
bedded on a large scale.
Delaware stage.
~ Unconformity ~-~-^\
200
Limestone containing large quantities of chert.
1 Reports of Iowa Geol. Surv.
APPENDIX.
GENERALIZED SECTION FOR IOWA — Continued.
559
Names of Formations.
Tihckness
in Feet.
Characteristics.
Proter- Cam- Ordovician.
/-.-rniV Kr-i'nr.
Maquoketa shales.
Possible unconformity^-
Galena-Trenton lime-
stone.
175
290
Drab, gray, and black; calcareous in parts.
Galena phase, dark buff, granular, highly
crystalline dolomite. Upper portions ar-
gillaceous.
Trenton phase, alternating beds of shale
and non-magnesian limestone; green, buff,
and blue.
St. Peters sandstone.
100
White, brown, yellow, red; coarse and friable.
Oneota formation (in-
cludes Shako pee,
New Richmond and
Oneota proper).
300
Dolomite with some interstratified sandstone.
i r
- \ St. Croix sandstone.
1000 +
Slightly consolidated, disintegrating rapidly on
weathering; includes thin, argillaceous, and
calcareous seams, and some greensand.
> f
3 -j Sioux quartzite.
> I
?
Hard, vitreous quartzite grading locally into
loose sandstone; color usually red to dark
purple, or almost white.
560
APPENDIX.
SECTION FOR ARKANSAS.*
Names of Formations.
Thickness
in Feet.
' Characteristics.
1
!'
&
I
Potea beds.
3500
Mainly shales and sandstones with some coal-
beds.
Productive beds.
1800
Barren beds.
18480
Discontinuity.
Millstone grit.
500
Sandstones and conglomerates; friable to
hard; buff or brown, with occasional seams
of limonite.
Boston group.
Kessler limestone.
3-15
Thin-bedded.
Coal-bearing shale.
60-90
Shale, in places highly fossiliferous; thin coal-
seams.
Pentremital lime-
stone.
0-90
Impure, dark-colored, and loose-textured;
sometimes interbedded with sandstone.
Washington sand-
stone and shale.
40-75
Varying proportions of sandstone and gray
shale.
Archimedes lime-
stone.
0-80
Light-gray limestone, rich in Archimedes.
%
i
9
|j
G'
•"N^X-X
Jj
§*s
^^^w
Marshall shale.
0-250
Black, bituminous.
Bates ville sandstone.
10-200
Sometimes massive; sometimes thin-bedded.
Spring Creek Black
shales and limestone.
300
Shales and limestones, black to bluish or yel-
lowish brown in color.
Wyman sandstone.
0-9
Boone chert.
370
Interbedded chert and limestone ; contains the
St. Joe marble, 25-40 feet.
. Eureka shale.
0-50
Thin-bedded, black.
1 !> Sylamore sandstone.2
^^ Unconformity -^^^-
5 J St. Clair limestone
* 1 and Carson shale.
~^ Unconformity ~~^~
0-40
80
Hard or saccharoidal.
Underlain by shales which locally bear man-
ganese ore and phosphates in commercial
quantities.
1 Branner, Amer. Jour. Sci. 4th series, Vol. 2, 1896, p. 235 ; Hopkins, Ark. Geol. Surv. Ann
Kept 1890, Vol. IV, pp. 10, 90-125, 253; Penrose, Ark. Geol. Surv. Ann. Kept. 1890, Vol. I, pp.
113-197 215- Williams, Ark. Geol. Surv. Ann. Kept. 1892, Vol. V, pp. 273-356; Taff, 22d Ann.
Kept. U. S. Geol. Surv. Part III, pp. 389-392. Section above the Millstone grit is for the Arkansas
vallev region. Section below this region is for northern Arkansas.
2 Sylamore sandstone usually given as the Phosphate horizon, but unpublished work places i
in the Carson shale.
APPENDIX.
SECTION FOR ARKANSAS — Continued.
561
Names of Formations.
Thickness
in Feet.
Characteristics.
Ordovician.
Polk Bayou limestone.
75
Highly crystalline limestone in massive layers;
light gray to chocolate-brown.
Izard limestone.
285
Fine-grained; compact, non-fossiliferous, even-
ly bedded; mainly dark blue, but varies to
buff, light gray, and almost black.
Saccharoidal sand-
stone.
125
Friable; usually white, but often brown; some-
limes quartzitic.
Calciferous or Magne-
sian limestone.
1625
Brownish-gray arenaceous dolomite, few fos-
sils.
562
APPENDIX.
SECTION IN INDIAN TERRITORY.1
Names of Formations.
Thickness
in Feet.
Characteristics.
Devo- Missis- .
nian. sippian. Pennsylvaman.
Summit removed by
erosion.
Seminole conglom-
erate.
50 +
Conglomerate of white chert in brown sandy
matrix, succeeded by brown sandstone.
Holdenville shale.
260
Blue and yellow clay shale, with thin siliceous
limestone- and sandstone-beds.
Wewaka formation.
700
Massive brown friable sandstone, with soft,
thin limestone lentil in lower part.
Wetumka shale.
120
Clay shale above, sandy shale and thin sand-
stone below.
Calvin sandstone.
145-240
Thick-bedded and hard, friable, ferruginous,
and shaly towards the south.
Senora formation.
140-485
Brown sandstone, thick-bedded to shaly.
Stuart shale.
90-280
Blue and black, with sandstone lentil.
Thurman sandstone.
80-260
Brown sandstone, shale, and cherty conglom-
erate.
Boggy shale.
2000-2600
Shale, shaly sandstone, and brown sandstone.
Locally, thin siliceous limestone-beds, and
coal near the base.
Savannah sandstone.
750-1100
Brown sandstone and shale.
McAlester shale.
1150-1500
Shale, brown sandstone, and conglomerate of
white chert pebbles.
Hartshorne sand-
stone.
150-200
Brown sandstone, varying to chert conglom-
erate.
Atoka formation
(Chickahoc chert
lentil).
3200
Shale and brown sandstone, variable in thick-
ness, texture, and hardness. Lentil of chert
and limestone, and a conglomerate bed of
iron concretions.
Wapanucka lime-
k stone.
100-150
White oolitic and blue limestone, shale, and
locally cherty calcareous sandstone.
Caney shale.
1500
2. Blue shale with sandy lentils and ironstone
concretions.
1. Black fissile shale, with dark-blue fossilifer-
ous limestone concretions.
Woodford chert.
600
Thin-bedded chert and fissile black shale; bl ue
flint lentils at base.
1 Above the Savannah sandstone the section is taken from the Coalgate (I. T.) folio; remainder
from the Atoka folio. Taff, U. S. Geol. Surv. In the area covered by the Talequah folio, there
are unconformities between the Ordovician and the Silurian, the Silurian and the Devonian, the
Devonian and the Mississippian, and the Mississippian and the Pennsylvanian.
563
SECTION IN INDIAN TERRITORY — Continued.
Names of Formations.
Thickness
in Feet.
Characteristics.
oJ&*{fi£ °«>°™ St
Hunton limestone.
160
Light-colored, with flint and chert concretions
in the upper part.
: Sylvan shale.
50-100
Blue clay shale.
Viola limestone.
750
White, bluish, with flint concretions in the
middle.
Simpson series.
1600
5. Sandstone, calcareous sandstone, and shale
(at top).
4. Thin fossiliferous limestone and shale.
3. Calcareous sandstone and shale.
2. Fossiliferous limestone and shale.
1. Sandstone and shaly beds.
Arbuckle limestone.
4000-6000
White and blue, partly massive and partly
thin-bedded.
i- Regan sandstone.
^ Unconformity -^—^^-
Tishomingo granite.
50-100
?
Coarse, dark brown.
Coarse red granite with dikes of basic rock.
Strata folded and faulted.
564
APPENDIX.
GENERALIZED SECTION FOR NEBRASKA.'
Names of Formations.
Thickness
in Feet.
Characteristics.
^aS1" mSn. Cretaceous. Oligocene. Miocene. ™£ Quaternary.
Alluvium.
Sand-hills.
Mainly dunes.
Loess.
Fine sandy loam of pale brownish-buff color.
Glacial drift.
Equus beds.
Gray sands; eolian in part.
Ogallala formation.
150-300
Calcareous grit, sandy clay, and sand; largely
fluvatile.
Arikaree formation.
0-500
Gray sand with beds of pipy concretions;
fluvatile and eolian.
Gering formation.
0-200
Coarse sands, soft sandstone, and conglomerate;
largely fluvatile.
Brule clay.
320-600
Pinkish clays, hard, and more or less arena-
ceous; fluvatile and lacustrine.
Chadron formation.
30-60
Pale greenish-gray sandy clay; fluvatile or
lacustrine or both.
' Pierre clay.
2000 +
Dark gray and soft ; marine.
Niobrara formation.
50
Chalky limestone and shale; marine.
Benton shale.
600 +
Dark gray or black; marine.
Dakota sandstone.
400
Brown; probably non-marine in part at least.
• Permian limestone.
200
Buff limestones and shales; marine.
Cottonwood lime-
stone.
1000
Massive, of light color.
Wabaunsee forma-
tion.
Limestones, shales, sandstones, and thin coal-
beds.
Strata nearly horizontal.
i Darton, 19th Ann. Rep., Part IV, p. 732, U. S. Geol. Surv.; also Scotts Bluff (Nebraska) folio,
U. S. Geol. Surv.
APPENDIX.
SECTION IN EASTERN WYOMING.1
565
Names of Formations.
Thickness
in Feet.
Characteristics.
Proter-< Missis- > Pennsyl- Permian. Triassic and Jurassic. ! Cretaceous. $ Oligocene. Ne°- Quater'
ozoic2 ) sippian. ( vanian. / ( cene. nary.
]
}• Alluvium.
1-30
Gravel, sand, and silt.
Arikaree formation.
700 +
30-40
2. White sand and soft sandstone, with pipy
concretions ; non-marine.
1. Gray sandstone and conglomerate.
Brule formation.
250
Flesh-colored sandy clay, with lenses of sand-
stone; non-marine.
Chadron formation.
- Unconformity ~~ —
Graneros formation
(Colorado).
60 +
120 +
Green, maroon, and pink sandy clay and gray
sandstone; non-marine.
Gray flaky shale, with concretions and massive
sandstone near top; non-marine.
Dakota sandstone.
,
- Unconformity ^-^^
Morrison clay.
(May be Lower Cre-
taceous.)
250-300
100
Massive buff, gray, and reddish sandstone and
quartzite, with thin beds of clay and shale;
non-marine.
Clays of various colors, with a thin bed of
limestone; probably non-marine.
Sundance formation.
200
Buff sandstone, with interbedded clays near
top; marine,
Spearfish sandstone.
("Red beds," possi-
L bly Permian.)
450
Dark reddish-brown, medium-grained, thin-
bedded; limestone beds, and thin sheets of
gypsum in lower parts; salt lake deposits.
Minnekahta lime-
stone.
20
Gray to purplish, thin-bedded.
Opeche formation.
60
Bright-red, thin-bedded sandstone, with red,
flaky shale; marine.
Hartville formation.
{
~ Unconformity -~
>• Guernsey formation.
- Unconformity — ~~
Whalen group and
intrusive granite.
650
150
3. Massive gray limestone, some beds cherty:
occasional beds of white, gray, buff, ana
red sandstone.
2. Red shale and gray limestone.
1. Red quartzite streaked with white.
Conglomeratic quartzite, with sandstone and
gray limestone above.
Quartzite, schist, siliceous limestone, and
gneiss. Masses and dikes of intrusive gra-
nitic rocks.
Strata horizontal or with gentle dips.
1 Smith, W. S. T., Hartville, Wyo., folio, U. S. Geol. Surv.
2 Proterozoic given as Algonkian in folio.
566
APPENDIX.
GENERALIZED SECTION FOR THE BLACK HILLS.
Names of Formations.
Thickness
in Feet.
Characteristics.
( Upper Cretaceous.
Vr_ Tri_ < ™.-~~
an(?). assic. Jurassic. J Lower Cretaceous. Colorado. Montana. cene".
(White River for-
mation.
0-200
Porous, crumbling clay, with coarse sand-
stone and conglomerate; non-marine de-
posits, commonly classed as lacustrine.
Laramie formation
2500
Massive sandstone and shale; mainly non-
marine.
(Fox Hills forma-
tion.
250-500
Sandstone and shale; marine.
[ Pierre shale.
1200
Dark gray; marine.
' Niobrara forma-
tion.
225
Chalk and calcareous shale; marine.
Carlile formation.
500-750
Gray shales with thin sandstone, limestone,
and concretionary layers; marine.
Greenhorn lime-
stone.
50
Impure, slabby; marine.
Graneros shale.
900
Contains lenses of massive sandstone; marine.
Dakota sandstone.
35-150
Massive, buff; non-marine, at least in part.
Fuson formation.
30-100
Fine-grained sandstone, and massive shales;
white to purple; no fossils.
Minnewaste lime-
stone.
0-30
Gray; no fossils.
Lakota formation.
200-350
Massive buff sandstone, intercalated shale;
largely non-marine. Fossils cycads.
Morrison shale.
Unconformity -^^^
Beulah shale.
0-125
0-150
Massive, and of gray, green, and maroon col-
ors; thin beds of sandstone.
Pale grayish green; marine.
Unkpapa sand-
stone.
0-250
Massive, white, purple, red, and buff; marine,
shallow-water deposits.
Sundance forma-
tion.
60-400
Dark drab shales and buff sandstones; mas-
sive red sandstone at base; marine, shallow-
water deposits.
:Spearfish forma-
tion.
350-500
Red sandy shales with gypsum-bed; salt lake
deposits.
• Minnekahta lime-
stone.
30-50
Thin-bedded, gray; marine.
S [ Opeche formation.
90-130
Red slabby sandstone, and sandy shale ; marine.
1 Barton, 21st Ann. Rep. U. S. Geol. Surv., Part IV, pp. 503-504, and Barton and Smith, Edge-
mont folio, U. S. Geol. Surv. Ordovician inserted from Jaggar, 21st Ann. Kept., Part III, U. S.
Geol. Surv., pp. 178-181.
APPENDIX.
GENERALIZED SECTION FOR THE BLACK HILLS — Continued.
567
Names of Formations.
Thickness
in Feet.
Characteristics.
£e I"
g.SS ! Minnelusa forma-
111 tion"
400-450
Sandstones, mainly buff and red; in greater
part calcareous; some thin limestone in-
cluded.
i Pahasapa 1 i m e -
•g fl- stone.
250-500
Massive gray limestone.
.2 3« Englewood lime-
S stone.
25
Pink, slabby limestone.
•A . r
Massive limestone, usually
buff with brown or
-§.2 j Ordovician.
80
reddish spots. Present
only in northern
o ° L
Black Hills region.
g c i j Deadwood forma-
tion.
o^ L
4-150
Red-brown quartzite and
conglomeratic.
sandstone, locally
•*- Unconformity ^ — —•
-~^~-
-^-^- ^-X^-^^-^X-^X-N-^^-^*^«^%»
g]
if [
Crystalline schists.
568
APPENDIX.
SECTION IN CENTRAL MONTANA.
Names of Formations.
Thickness
in Feet.
Characteristics.
J, b
Alluvium.
0-50 +
6-1
Glacial drift.
0-100 +
v^-^-v--'^
- Unconformity ^^^
— -
ftl
\ •! Smith River beds.
0-800
Clay, sand, conglomerate, and tuff; vertebrate
remains; non-marine.
tL^
- Unconformity ^^^^
___^_^_ ,
Dark-brown tufaceous sandstone, with local
Livingston for-
mation.
3300
beds of conglomerate, shale, limestone, and
pyroclastic materials. Estuarine or lacus-
trine conditions, followed by land conditions,
and then by marine.
-v
^r- Unconformity^^-
1
Laramie forma-
tion.
900-1050
Light-gray or yellow sandstone; shale-beds in
upper portion; workable seams of coal; plant
remains and brackish-water shells.
1
•
4. Lead-gray arenaceous shale, with thin beds
P Montana forma-
of sandstone; marine.
§ . tion.
3. Calcareous shale with limestone concretions
H
o .2 Colorado forrna-
| o3 tion.
2800-3500
and interbedded sandstones; marine.
2. Black bituminous shale.
g ^ Dakota forma-
1. Quartzite; sandy shale below and conglom-
>
H tion.
erate at base; fresh-water fossils in limestone
I
I
near top; fluvatile or lake deposits.
S.| | Ellis formation.
*-s J
90-120
Arenaceous limestone and shale; marine.
5. Alternating beds of limestone and sand-
stone.
4. Green shale with interbedded limestones.
-1
Quadrant forma-
i jrjfi
3. Limestone with sandstone beds.
tion.
I'lUU
2. Green shale with interbedded limestones,
°53
.
often oolitic.
.2
1. Red clay with yellow lumps.
CO
All shallow-water, marine deposits
Madison limestone
1025
Massive and white above, thin-bedded, dark
gray below.
>d ! Monarch forma-
<D r/~ *\ •
aSl t>°"-
165
Chocolate-brown, granular limestone.
i Weed, Little Belt Mts. (Mont.) folio, U. S. Geol. Surv. Combination of the sections there given.
Ellis formation classed as Jura-Trias in the folio. What is here marked Yellowstone series is given
as Yellowstone formation, Belt series as Belt formation, Barker series as Barker formation, and Proter-
ozoic as Algonkian.
APPENDIX.
SECTION IN CENTRAL MONTANA — Continued.
569
Names of Formations.
Thickness
in Feet.
Characteristics.
idle Cambrian.
Ij
BJ|
{ Gallatin lime-
stone.
Flathead quartz-
ite.
1300
3. Massive and thin-bedded limestone.
2. Dark-green and purple micaceous shale, with
interbedded limestone and limestone con-
glomerate.
1. Pink quartzite and sandstone.
3 l
«- Unconformity -~~ — ^
^ •
^~~~^~ ~^^-~-^x-^^>^^^ -s_ -^-^ **^ »
Spokane shale.
91 n
4. Red.
'3
.1
1 -
Grey son shales.
Newland lime-
stone.
950
560
3. Lustrous gray sericitic shale and slate.
2. Dense, dark-colored, bluish gray, impure,
with interbedded slate.
1
Chamberlain
shale.
2080
1. Slate, and compact, indurated, dark-gray
shale.
Neihart quartzite.
700
Massive-bedded.
*» Unconformity -^~^
— _^ ^_ _
Banded gneiss and mica schist, with intrusive
porphyries, diorite, and syenite.
,
Paleozoic and Mesozoic strata folded, faulted, and cut by igneous rocks. Ter-
tiary beds nearly horizontal.
570
APPENDIX.
SECTION IN WEST CENTRAL COLORADO. 1
Names of Formations.
Thickness
in Feet.
Characteristics.
I J / Eocene or
( Pennsylvanian. S Jurassic. Cretaceous. < later.
West Elk breccia.
<- Unconformity ->
Ruby formation.
-~-^- Unconformity— ^-
Ohio formation.
(Local only.)
vx- Unconformity—
Laramie formation.
3000
2500
2000
Upper part volcanic breccia; lower part fri-
able tuff, with sandstone beds. Material
mainly dark hornblende-andesite and pyrox-
ene-andesite, with some non-eruptive de-
bris in the lower part.
Conglomerate, sandstone, and shale alternat-
ing; chiefly of igneous debris, with quartz
sand intermingled; conglomerate at base;
probably non-marine.
Quartzose sandstone, with vari-colored jasper
and clay at base; probably non-marine.
Sandstone and shale with workable coal-beds
in the lower 400 feet; arenaceous shale pre-
dominates in upper half. The coals are an-
thracite (subordinate), coking, and dry bitu-
minous. Sand and shallow-water deposits;
partly non-marine.
Montana formation.
2800
Fine-grained yellow sandstone (Fox Hills) in
upper part, 300 feet; lead-gray shale, with
numerous lenticular bodies of limestone
(Pierre formation) below; marine.
Niobrara formation.
100-200
Upper two thirds gray, calcareous shale; the
lower third light-gray limestone; marine.
Benton formation.
150-300
Black shale, with thin limestone-beds near top;
ironstone; marine.
Dakota formation.
40-300
White quartzite; conglomerate at the base;
local fire-clays; non-marine in part at least.
•
Gunnison formation.
- Unconformity ^~^^~
Maroon conglomer-
ate.
Possible unconformity
Weber limestone.
Unconformity ~~~~~
350-500
2500
2000
100-550
Upper two thirds drab, green, yellow, and
pink clays, with thin beds of limestone.
Heavy white quartzite below; non-marine.
Conglomerate and sandstone in heavy beds;
material chiefly from the Archean, but the
conglomerate contains limestone derived
from the earlier Carboniferous beds. Occa-
sional thin beds of fossiliferous limestone.
— »,. — - — , -Possible unconformity —
Quartzose, conglomerate, grit, and sandstone,
with pebbles derived from Carboniferous be-
low. Thin beds of fossiliferous limestone.
Dark-gray to black shale, with thin beds of
limestone carrying black chert.
1 Emmons, Cross, and Eldridge, Anthracite and Crested Butte, Col., folio, U. S. Geol. Surv
APPENDIX.
SECTION IN WEST CENTRAL COLORADO — Continued.
571
Names of Formations.
Thickness
in Feet.
Characteristics.
j, fl- (
The upper third massive, blue, and cavernous;
cc'S, <{ Leadville limestone.
400-525
the lower two thirds bedded, gray to brown;
§.& [
dark cherts.
•^Apparent unconformity -
^^^^~^
— -^
'> • \
•p.SS 1 Yule limestone.
O [
350-450
80 feet of green, pink, and yellow shale and
thin limestone at top; middle portion mas-
sive gray limestone with white chert.
« f
S-c I
g-g ^ Sawatch quartzite.
*— ' jg
50-350
Upper two thirds red quartzite, containing
glauconite. The lower third quartzite with
conglomerate at base.
0 I
^ Unconformity -~—^>
*w
e 1
3 }• Archean.
Granite, gneiss, and schist.
4J
Strata folded, faulted, and cut by igneous intrusions.
572 APPENDIX.
GENERALIZED SECTION FOR SOUTHWESTERN COLOR ADO.
Names of Formations.
Thickness
in Feet.
' Characteristics.
Alternating rhyolite and quartz-latite flows
Potosi volcanic series.
1250
and tuffs, flows predominating near base.
Some thin upper flows in Potosi Peak are
glassy.
^xx-
~ Unconformity
- ~ ^
02*
100-3000
Andesite flows, tuffs, and dikes, with both
augite and hypersthene.
V
•^-Unconformity —
xx^ xx^-x^x-
^V^V^^v^^^x-x^v^vx-V^X^ V^X^^XV^ -^ xvx-xxx^v^x^
O
Flows, tuffs, breccias, and dikes of dark horn-
'3
Burns latite.
1200
blendic quartz-bearing latite of andesitic
o
habit.
.
|'
^ Unconformity -^
^^^~^~^
^^^^XX^X^^X^X^-^^x^X^X^XX^X^X^^XX^^X^X^^XX^X^X^X-
*! <
|
Eureka rhyolite.
1800
Massive flows, dikes, and bedded tuffs, the
former greatly predominating.
04
m
^Unconformity *^
-WX-NX-X^VX-XX-
-X^X^X^X^-X^X^-X^X^X^X^^-X^X^^XVX^X^X-X^X^X^X^X^X^X^-X^.
H
Picayune andesite.
500
Augite-andesite tuff, breccia, or agglomerate,
and massive flows. Base not known,
>s*+s-
— Unconformity-*^^
^^^^-~ —
~^^~~~^ -x^X^X^^X^X^ ^^~-^^^^^^^
Almost exclusively andesitic debris. Well
San Juan tuff.
100-2000
stratified near base, coarser and less dis-
tinctly bedded above. No fossils known.
-•vyv
•~ Unconformity*^*-^-
^S^^^^r
-^X^X^X-^Xx^X^XX^X^X^^^x^x^X-^X^X^x^Xx^^^X^^x^xx-xXXXX
Contains pebbles and bowlders of schist, gran-
ite, and quartzite, with some Paleozoic lime-
Telluride conglomerate.
0-200
stones and other sediments. Thickens
westward to 1000 feet, and here includes
sandstones and shales.
^~v^ Unconformity-*^*^
V ^
~~- ^ ^^ VX-X^X^X^XX^X^X^ ^x^^xx.
1
Bright-red sandstones and pinkish grits and
*£ '
Cutler formation.
1000 +
conglomerates, alternating with reddish
B
sandy shales and limestones.
Rico formation.
Dark red-brown sandstone and pink grits, with
300
intercalated greenish or reddish shale, and
g
sandy, fossiliferous limestone.
*3
Hermosa formation.
Limestones, grits, sandstones, and shales.
I-
2000
Heavy bedded limestone predominates in
middle and upper parts, sandstone and shale
2
below. Fossils numerous.
g
(S
Red calcareous shale and sandstone, with thin,
Molas formation.
75
fossiliferous limestone lenses, and chert,
limestone, and quartzite pebbles.
v~v^ Unconformity -v^^
^^^^~^
-xx-v ^X^Xx-x^x^x^x^^x^x^-v^xv^vX^X^-x^vx-VX-Xx-XX^X^-VXX
1 Cross and Howe, Silverton folio, U. S. Geol. Surv.
APPENDIX.
GENERALIZED SECTION FOR SOUTHWESTERN COLORADO — Continued.
573
Names of Formations.
Thickness
in Feet.
Characteristics.
.49
i'l-
13 &,
Pale yellow to buff, compact; lower third
s-a
Ouray limestone.
200 +
shaly, with thin quartzites; abundant fossils
indicate, Devonian age of lower two thirds.
d
and Mississippian age of upper part.
flfi
'3
o •
&
Thin limestone, sandstone, and calcareous
t— i
Elbert formation.
25-100
shale; contains fragmentary remains of
fishes.
v, — ^-^>
- Unconformity ^^^x^.
^s^^s^~~
^VX^^^^^^^V^N^^V^X^X^^^V^X^V^VX^X^V^N^V^VX^
Light gray, pink, or yellow; massive and con-
SSj
air
Ignacio quartzite.
0-200
glomeratic below, thin-bedded with shale or
sandy partings in medial zone, massive above.
u-° i
Obolus sp. ? found near middle.
- — 'x.
- Unconformity ^~~^-
^ 0 r^^
^^~^^V^-^VX^^V^V^ ^^^~^^^^~
Protero-
zoic.
:Uncompahgre for-
mation.
8000 +
Massive white or smoky quartzite and dark
slate, alternating in thin beds locally. No
fossils found.
d (
Schist and gneiss of light and dark colors,
c3 '
1
often alternating. Intruded by granite and
cut by basic dikes, many of which have
< I
been mashed.
574
APPENDIX.
GENERALIZED SECTION FOR THE GRAND CANYON REGION.*
Names of Formations.
Thickness
in Feet.
Characteristics.
• Ji Missis- Pennsyl- ) Triassic and Cre- Ter-
isippian. vanian. ( Permian. Jurassic. taceous. tiary.
Tertiary.
815
Marls and shales, with sandstone and limestone.
Fresh- and brackish-water deposits.
.
Cretaceous.
3095
Soft, more or less calcareous sandstones and
dark argillaceous and carbonaceous shales
containing extensive beds of coal; mainly
marine, in part non-marine.
Jurassic.
Jura-Trias.
960
3430
3. Bright-red calcareous and gypsiferous
shales, with some sandstone; in part
marine.
2. Massive white sandstone; probably marine.
1 . Red and buff sandstones, with beds of shale
and gypsum; largely non-marine.
Upper Permian.
— ^ Unconformity^^-
Lower Permian.
•* Unconformity ^^^^
Upper Aubrey lime-
stone.
710
145
805
Gypsiferous and arenaceous shales and marls;
shaly limestone at the base; partly non-
marine.
Similar to the above, with more massive lime-
stone at the base; largely marine.
Massive, cherty limestone with arenaceous
gypsiferous bed; calciferous sand rock below.
Lower Aubrey sand-
stone.
1485
Friable, reddish sandstone, becoming more
compact and massive below; a little lime-
-stone.
Red Wall lime-
stone.
- Unconformity -^~^^
962
Arenaceous and cherty limestone above, with
massive limestone and chert below.
«•§ '
Q fl
•**s^~s-^s*
Temple Butte lime-
stone.
•«• Unconformity -^ — -~-
'
94
Impure limestone and sandstone.
• O
Tonto series.
1050
Calcareous and arenaceous shales above, sand-
stone below.
\ Protero- ( I
) zoic. > C
I
- Unconformity -s* — ~
' Chuar.
5120
Shales, sandstones, and thin beds of limestone.
1 Unkar.
- Great unconformity^
6830
Sandstones, shales, interbedcied lavas, and
some limestone.
1
(Vishnu.
1000 +
Schists, gneisses, etc., with dikes and veins of
granite.
5ase not exposed.
1 Walcott, Jour, of Geol., Vol. Ill, pp. 317-324; Bull. Geol. Soc. Amer., Vol. I, p. 50; Amer.
Jour. Sci., 3d series. Vol. 20, 1880, p. 222. Dutton, Tertiary History of the Grand Canyon, pp. 35,
40. Vishnu is classed as Algonkian in some of the above.
APPENDIX.
575
SECTION IN ARIZONA.*
Names of Formations.
Thickness
in Feet.
Characteristics.
Red nodular shales with cross-bedded, buff,
Centura formation.
1800 +
tawny, and red sandstones; beds of impure
limestone near base.
|'^
Thick-bedded, hard, and fossiliferous above,
-S 2
Mural limestone.
650
and thin-bedded, arenaceous, and fossiliferous
below.
§i
o 2
eg
Morita formation.
1800-
2000 +
Buff, tawny, and red sandstones, and dark-red
shales, with occasional thin beds of impure
limestone near the top.
Glance formation.
25-500
Bedded conglomerate; pebbles angular and
chiefly of schist and limestone.
— Unconformity • ~-
X^-^^^v,
^-— ^^~v^v^-
"gr»g* Naco limestone, with
g'S 1 intruded granite
£ g ^ porphyry.
3000 +
Chiefly light-gray, compact limestone, in beds
of moderate thickness; fossils abundant.
. r
2 fi
i*|N Escabrosa limestone.
9.8*
700
Thick-bedded white, and light-gray limestone,
with abundant crinoid stems.
cc I
£ § | Martin limestone.
Q'S J
340
Dark-gray, fossiliferous.
~- Unconformity ^~-^^
^^^^^^^^^^^^^^^s^^^^^^ —
S § J Abrigo limestone.
^'n | Bolsa quartzite.
770
430
Thin-bedded, impure, cherty.
Cross-bedded, with basal conglomerate.
I
<~> Unconformity -^^^
^^v^^
^v x~v^
a
||
• Final schist.
Sericitic schists.
0
1 Ransome, Bisbee, Ariz., folio, U. S. Geol. Surv.
576
APPENDIX.
SECTION IN THE EUREKA DISTRICT, NEVADA.*
fi
ames of Formations.
Thickness
in Feet.
Characteristics.
.
Upper Coal-measures
500
Light-colored blue and drab limestones.
1
Weber conglomerate
2000
Coarse and fine conglomerates, containing chert
and layers of reddish-yellow sandstone.
1<
1
Lower Coal-meas-
ures.
Transition fauna at
base.
3800
Heavy bedded dark-blue and gray limestone,
with intercalated bands of chert, argillaceous
beds near base.
A fl
J*i/
! Diamond Peak
quartzite.
3000
Massive gray and brown quartzite, with shales
at summit.
d
.2
White Pine shale.
2000
Black, sometimes arenaceous, with intercala-
tions of Iriable sandstone, varying from point
to point.
1
Nevada limestone.
6000
Massive to thin-bedded, of variable color and
texture; highly fossiliferous.
i»"C
•^^^"^s-
4
Lone Mountain lime-
stone.
^ Unconformity -^~~ —
Eureka quartzite.
1800
500
Trenton fossils at base; Silurian fossils above.
Compact and vitreous, white, and blue, reddish
near base.
Ordovicn
Pogonip limestone.
2700
Tnterstratified limestones, argillites; arena-
ceous beds at base; fine-grained, bluish-gray.
Limestone distinctly bedded above; highly
fossiliferous. Mingling of Cambrian and Or-
dovician fossils at the base.
|
r Hamburg shale.
350
Chert nodules abundant, especially near the top.
—
,0
Hamburg limestone.
1200
Dark gray and granular; only slight traces of
bedding.
1
OH
b
Secret Canyon shale.
1600
Yellow and gray argillaceous shales, passing
into shaly limestone ; interstratified layers of
shale and thin-bedded limestones near top.
Middle
Cambrian.
Prospect Mountain
limestone.
3050
Gray, compact limestone, bedding planes im-
perfect. Olenellus fauna at base.
fel f
JH
W V
Prospect Mountain
quartzite.
1500
Bedded brownish-white quartzite; layers of
arenaceous shale; no fossils.
1 Hague. Mon. XX, pp. 13-87, U. S. Geol. Surv., and Walcott, Mon. VIII, U. S. Geol. Surv
pp. 8 and 283.
APPENDIX.
577
SECTION IN SOUTHERN CALIFORNIA.1
Names of Formations.
Thickness
in Feet.
Characteristics
A .
[Alluvium, etc.
1-100
Clay and gravel.
-*3 £* .
O>fl
Terrace deposits and
dune sand.
10-400 ±
Sand and gravel.
*f
[Paso Robles forma-
tion.
1000 +
Sandy and marly clay, with pebbly conglomer-
ate; fragments of Monterey shale at bottom.
o
— v^"v^-~
~ Unconformity ^^~ — •"*•
^,-0^^^^^-
^^^^-^^^^^^^^^^^^^^^^^^^^-^^^^^^^^^^^^^^^^^^^^
p
Pismo formation
Sandstone and conglomerate at the base,
(in sow^ part of
3000 ±
siliceous shale, diatomaceous earth, and soft
¥
area) .
sandstone above.
5 '
0
a
Santa Margarita
(in north part of
area).
1550±
Alternations of conglomerate and sandstone,
with layers of diatomaceous earth and pumice.
-^x-x^x
^ Unconformity -^v^~
-^^^^^~^*^
^~ ^~- ^_-^ ^^
Thin-bedded bituminous shale, largely sili-
ceous, with diatomaceous earth in places;
§
Monterey shale.
5000-7000
carries oil and asphaltum. Toward base,
limestone, with volcanic ash below, and
§
sandstone at bottom.
Vaquero sandstone.
0-500
Sandstone and conglomerate.
•*^V^-v-X-^.
~ Unconformity •^^^
~^^^^^
; w .
0 | '
Atascadero forma-
tion.
3000-4000
Sandstone with some conglomerate and shale.
\XW*»^
.
- Unconformity ^ — ~-
^v^^v^^
1 .
11-
o-*-
Toro formation
(Knoxville.)
3000 db
Dark clay shale, with irregular beds of conglom-
erate at bottom and near the middle.
0 °
L
~v^vy*Vy
^ Unconformity ^^^^^
^~^~^.
— — „
U.
[San Luis formation
(Franciscan).
1000 ±
Chiefly sandstone, but locally much shale;
numerous radiolarian jasper lentils, and some
contact metamorphic schist.
*^S_XXXV.
~ Unconformity ~^~^~
^
^^™^ ^^ ~^^^^~^
Granite.
1 Fairbanks, San Luis folio, U. S. Geol. Surv0 The Comanchean and Cretaceous are classed as
Cretaceous in the folio.
578
APPENDIX.
SECTION IN CENTRAL WASHINGTON.1
Names of Formations,
Thickness
in Feet.
Characteristics.
Rhyolite
^- Unconformity^
Roslyn formation.
100-800
3500 ±
Compact lava and tuff.
Massive yellow sandstone with some shale.
Roslyn bed of coal in upper part, and other
less valuable beds at other horizons.
Teanaway basalt.
-> — ^ Unconformity — ~
Swauk formation.
>~ Unconformity ~-
Igneous and metamor-
phic rocks.
300-4000
3500-5000
Lava-flows with interbedded tuffs; lava
black and dark gray, compact or vesicular,
sometimes weathering brown or red.
Conglomerate schist and quartzose sandstone
and shale, of light and dark colors; cut by
numerous dikes of diabase.
1 Smith, G. O., Mt. Stuart foliOj U. S. Geol. Surv. The section given is for the northern part
of the Mt. Stuart quadrangle. In its southern part, Miocene, consisting of igneous rocks, Taneum
and esite and Yakima basalt below, and of the Ellensburg formation above, overlie the Eocene.
INDEX.
VOLUMES I, II, AND III.
INDEX.
THIS index is to the complete work. The references to Vol. I
are to its second edition. Vols. I and II each has an index of its
own.
Abbot, C. G., cited, ii, 6?7;
(and Langley), iii, 431
Abbot, M. L.,(and Humphreys,)
cited, i, 106, 202
Abbott, C. C., cited, iii, 516
Abietinae, iii, 95
Abra, iii, 295
Abrasion, by ice, i, 281
by streams, i, 119
by waves, i, 342
by wind, i, 38
Abngo limestone, iii, 575
Abysmal fauna, i, 671
life, Devonian, ii, 479
sea, i, 326
Acadian series, ii, 219, 241
Acanthaspls, ii, 463
Acanthodians, Devonian, ii, 489
Accret.on hypothesis, internal
temperature on, i, 564, 567
of earth's origin, ii, 38-78
recombination of material on,
i,568
Acer, iii, 173
Aceratherium, iii, 253, 289
Ac dasplds, Onondagan, ii, 467
Acondylacanthus gracilis, ii, 520
Acrocrinus amphora, ii, 532
Acrotreta gemma, ii, 285, 299
Actaeon shilohensls, iii, 294
Actinocrinidae, ii, 520
Actinocrinus, ii, 522
lobatus, ii, 525
senectus, ii, 520
Actinolite, i, 447, 460
Actinopteria textiles, ii, 455
Actinopterygians, Devonian, ii,
489
Adacna, iii, 295
Adams, C. C., cited, iii, 532
Adams, F. D., cited, i, 474; ii
145, 204
Adams, G. I., cited, ii, 562; iii,
228, 245
Adaptations, climatic, of life in
Pleistocene, iii, 486
Adiantes, ii, 595
Adirondack region, Proterozoic
of, ii, 205
Adjustment of streams, struc-
tural, i, 146, 150
topographic, i, 162, 163, 197
Adobe, i, 467
Africa, Cretaceous of, iii, 171
Devonian of, ii, 448
Eocene of, iii, 219
Africa, Jurassic of, iii, 77
Lower Cretaceous of, iii,
129
Miocene of, iii, 279
Mississippian of, ii, 517
Oligocene of, iii, 252
Pennsylvanian of, ii, 590
Permian of, ii, 635
Pleistocene life in, iii, 501
Pliocene of, iii, 320
possible origin of placentals in,
iii, 224
Triassic of, iii, 38
Aftonian deposits, iii, 387
interglacial formation, iii, 493
interglacial stage, iii, 384
Agassiz, A., cited, i, 366, 604
Agassiz,L., cited, 1,321,322,323,
366
Agassizocrinus dactyliformis, ii,
532
Agate, i, 460
Agate structure, i, 436
Agathaumus, iii, 176
Agawa formation, ii, 180
Agelacrinidae, ii, 530
Agelacrinus, ii, 470
Agglomerate, i, 434, 467
Aggradation, by ice, i, 298
by streams, i, 2, 177
by wind, i, 25
in sea, i, 333, 355
terrestrial, iii, 296
Aggradation deposits, Pliocene,
iii, 296
Aggrading streams, character-
istics, i, 179, 187
Agitation and C02 of ocean, ii,
667
Agnatha, ii, 482
Agnostus interstrictus, ii, 298, 299
obtusilobus, ii, 299
Agoniatites vanuxemi, ii, 471
Agraulus, ii, 299
Agriopoma, iii, 295
Air-breathing life, oldest aquatic,
ii, 529
Airy, Sir G., cited, i, 341
Aistopoda, ii, 607, 608
Ajibik quartzite, ii, 150, 179, 180
Alabama, Eocene section of, iii,
199
(and Georgia), section of
strata in, iii, 551
Alabaster, i, 460
of Triassic, iii, 34
Alaska, coal in, map of, iii,
203
Comanchean of, iii, 124
Cretaceous of, iii, 161
Eocene of, iii, 203
Jurassic of, iii, 67
Miocene of, iii, 270
Mississippian of, ii, 506
Oligocene of, iii, 248
Pennsylvanian of, ii, 556
Pliocene of, iii, 311
Silurian of, ii, 390
Triassic of, iii, 28
Albany series (Texas), ii, 563
Albertan drift, iii, 384
Albertia, iii, 40
Albian stage, iii, 132
Albite, i, 400, 460
Alcostephanus, iii, 92
Aldrich.T.H., (and Smith, E A.,)
cited, iii, 200, 244, 309
Alectryonia, iii, 91
Alethopteris, Mississippian, ii,
537
Pennsylvanian, ii, 595
Alferric rocks, i, 454
Algae, geologic contribution of,
i,653
influence on precipitation, i,
225
Algae and limestone, iii, 121
Algonkian, definition, ii, 162
(see Proterozoic)
Alkali -.alcic rocks, i, 458
Allegheny series, ii, 542, 557,
558, 560; iii, 554
Allen, J., cited, ii, 595, 596
Allen, J. A., cited, iii, 153
Allorisima subcuneata, ii, 616
Alluvial and talus deposits, iii, 472
Alluvial cone, i, 181-3
growth, i, 181
levees, i, 182
Alluvial deposits, i, 177-96
Alluvial fans, i, 181, 183
Alluvial plains, i, 181, 184-96
material of, i, 196
origin of, i, 184, 185
piedmont, i, 183
topography of, i, 196
Alluviation, i, 181, 196, 467
ill-defined, i, 183
Alpine glaciers, i, 251
phase of Triassic, iii, 30
remnants of Pleistocene life,
iii, 489
581
582
INDEX.
Alps, crustal shortening involved
in formation of, i, 549, 576
structure, i, 504. So?
Alveolina, iii, 241
Amalitzky, V., cited, ii, 630, 646,
650
Amber, i, 646; iii, 114
Oligocene, iii, 251
Amberleya dilleri, iii, 136
Amblypoda, iii, 232, 233
Ameghino, F., cited, iii, 220
American graptolites, ii, 345
Amethyst, i, 460
Amherst schist, iii, 546
Amia, iii, 87
Ammonites biplex, iii, 93
concavus, iii, 93
Cretaceous, iii, 187, 190
Jurassic, iii, 80
Lower Jurassic, iii, 91
macclintocki, iii, 93
Middle Jurassic, iii, 91
Permian, ii, 653
Triassic, iii, 50, 52, 56
Upper Jurassic, iii, 92
wosnessenski, iii, 93
Ammonoidea, iii, 52
Amphibians, Carboniferous, ii,
606
Eocene, iii, 240
Miocene, iii, 290
Mississippian, ii, 537
Permian, ii, 646
Amphibole, i, 460
Amphiboles, i, 400
Amphidetus, iii, 204
Amphistegina, iii, 294
Amusium, iii, 91, 92
Amygdaloid, i, 411, 467
Amyzon formation, iii, 210
Analcite, i, 460
Analyses, American river- waters,
i, 107
American spring- waters, i, 235
rain-waters, i, 107
river- waters, i, 106, 107, 108
sea- water, i, 324
waters of enclosed lakes, i,
392
Anamorphism, i, 446; ii, 142
Anamosa limestone, iii, 558
Anaptomorphus, iii, 239
Anatina austinensis, iii, 135
Ancestral sun, ii, 51
Anchippus, iii, 253, 286
Anchisaurus, iii, 43
colurus, iii, 44
Anchyloceras, iii, 134
Ancilla, iii, 294
Andalusite, i, 460
Anderson, F. M., cited, iii, 160
Anderson sandstone, iii, 549
Andes, snow- line in, i, 246
Andesine, i, 400, 460
Andesite, i, 467
Andrews, C. W., (and Beadnell,)
cited, iii, 284
Aneimites, ii, 595
Angisoperms, i, 657
introduction of, iii, 130
Angstrom, K., cited, ii, 671, 672;
iii, 444
Angulus, iii, 292
Anhydrite, i, 460
Animal kingdom, geologic con-
tribution of, i, 658-63
synopsis of, i, 659
Animikean system, ii, 183-191
composition of, ii, 183
deformation and erosion of, ii,
185
distribution of, ii, 186
igneous rocks of, ii, 184
Menominee region, ii, 187
Mesabi region, ii, 189
metamorphism of, ii, 185
sections of, ii, 186
thickness of, ii, 184
Vermilion region, ii, 190
Annelids, Devonian, ii, 467
Ordovician, ii, 361, 363
Upper Cambrian, ii, 299
Annularia longfolia, ii, 594
Mississippian, ii, 537
spenophylloides, ii, 594, 597
Anomalina ammonoides, iii, 241
Anomalocrinus incurvus, ii,
359
Anomodontia ii, 649, 651; iii,
42
Anoplotheca flabellites, ii, 459
Anoplotheres, Miocene, iii, 284
Anorthite, i, 460
Anorthosite, i, 467
Antarctica, snow-line in, i, 246
Ant-eaters, Pliocene, iii, 321
Antecedent streams, i, 169, 173
Anthozoa, Cambrian, ii, 286
Anthracite, i, 426, 460
origin of, ii, 577
Anthracotheres, Miocene, iii, 284
Anthracotherium, iii, 253
Anthrapalaemon gracilis, ii, 611
Anthropopithecus troglodytes, iii,
326
Anticlinal valleys, i, 159
Anticline, i, 504
plunging, i, 155, 157, 506
Anticlinoria, i, 504
Anticosti series, ii, 275
Antimony, i, 460
Antrim shales, iii, 553
Aparchites minutissimus, ii,
351
Apatite, i, 460
Apatosaurus, iii, 98, 100
Ape, Indian, iii, 326
Aphanite, i, 451, 452, 467
Aphorrhais prolabiata, iii, 189
Apishapa shale, iii, 155, 206
Apison shale, iii, 549
Aplite, i, 415
Appalachia, iii, i
Appalachian coal-field, ii, 546
river, i, 173
sections of Ordovician, ii, 315
Appalachians, crustal shorten-
ing due to folding, i, 549; ii,
125
extent of piracy in, i, 169
Appalachians, peculiarities of
drainage, i, 169
rejuvenation of streams in, i,
165
Aptian stage, iii, 132
Aqueous rocks, i, 467
Aquia formation, ni, 198
Aquitanian stage of Oligocene,
iii, 250
Arabellites ovalis, ii, 363
cornutus, 363
Arachnoids, Devonian, ii, 495
Arago beds, iii, 202, 264
Aragonite, i, 460
Aralia, iii, 133
Arapahoe formation, iii, 156, 158
Araucarioxylon, ii, 601
Arbuckle limestone, iii, 563
Area (Scapharca) stammea, iii,
292
Arch of earth's crust, strength
of, i, 582
Archaeocyathus rensselaericus,
ii, 287
minganensis, ii, 363
Archaeoptens bochsiana, ii, 593
Mississippian, ii, 537
Archaeopteryx macrura, iii, 102,
104
Archean, ii, 133-161
and planetesimal hypothesis,
ii. 137
bearing on origin of earth, ii,
155
complex, i, 18
composition of, ii, 140-143
defined, ii, 138
delimitations of, ii, 138, 160
distribution of, ii, 145
early views concerning, ii, 156
European, ii, 158, 159
general characters of, ii, 140
intrusions in, ii, 141, 142, 143,
154
map of, ii, 147
metamorphism of, ii, 144
origin of, ii, 140-145, 154
structure of, ii, 130, 131, 153
Archelon, iii, 181
Archeocalamites, Devonian, ii,
597
Archeozoic diastrophism, ii, 144
eon, ii, 83
era, i, 19; ii, 133
duration of, ii, 160
life of, ii, 159
Archimedes, ii, 531
limestone, ii, 562; iii, 560
swallovanus, ii, 532
Archinacella cingulata, ii, 353
Arctic Regions, Cretaceous of,
iii, 129
Jurassic of, iii, 77
Miocene of, iii, 281
Mississippian of, ii, 425
Oligocene of, iii, 251
Ordovician of, ii, 342
Pennsylvanian of, ii, 556, 588
Permian of, ii, 630
Triassic of, iii, 37
INDEX.
583
Arenaceous rocks, i, 468
Arenicolites woodi, ii, 285
Arenig beds, ii, 342
Argentina, Cambrian of, ii, 272
Cambrian fossils of, ii, 300
Jurassic of, iii, 78
Mississippian of, ii, 517
Permian of, ii, 538
Triassic of, iii, 37
Argillite, i, 448, 468
Arid regions, eiosion in, i, 131
Aridity, Salina epoch, ii, 388
Arietidae, iii, 91, 94
Arikaree beds, iii, 269, 564, 565
Aristozoae rotundata, ii, 283
Arizona, Comanchean in, iii, 117
Pliocene in, iii, 310
section of strata in, iii, 575
Arkansas, manganese ore of, ii,
377
section of strata in, iii, 560
Arkona beaches, iii, 397
Arkose, i, 422, 468, 645
Armadillos, Pleistocene, ii, 498
Pliocene, iii, 321
Armorican mountains, ii, 589
Armuchee chert, iii, 551
Arnioceras humboldti, i"» 9*
nevadanum, iii, 91
woodhulli, iii, 91
Arnold, D., (and Arnold, R.,)
cited, iii, 310, 311, 476
Arnold, R., cited, iii, 326, 495;
(and Arnold, D.), iii, 310,
311, 476; (and Haehl), iii,
263
Arrhenius, S., cited, i, 671, 672;
iii, 444, 445
Arsinoitherium, iii, 284
Artefacs, iii, 502
burial of, iii, 510
in talus, iii, 510
Artesian wells, i, 242
Arthroacantha, ii, 470
punctobrachiata, ii, 471
Arthrodirans, Devonian, ii, 461,
469
Arthrolycosa antiqua, ii, 611
Arthropoda, Cambrian, ii, 280
Devonian, ii, 490
geologic contribution of, i, 662
Permian, ii, 652
Triassic, iii, 57
Artiodactyls, Eocene, iii, 236
Artisia, ii, 60 1
Artocarpus, iii, 173
Arundel formation, iii, 59
Aschkinass, E., cited, ii, 671;
(and Rubens), iii, 444
Ashley, G. H-, cited, ii, 548; iii,
201, 214, 263, 274, 310, 315,
316, 475, 481; (and Blatch-
ley), ii, 424, 620; iii, 556
Ashley River marl, iii, 244
Asia, Archean of, ii, 159
Cambrian of, ii, 272
Cretaceous of, iii, 170
Devonian of, ii, 448
Eocene of, iii, 219
Glacial period of, iii, 424
Asia, Jurassic of, iii, 77
Lias of, iii, 77
Lower Cretaceous of, iii,
129
Miocene of, iii, 280
Mississippian of, ii, 517
Oligocene of, iii, 252
Pennsylvanian of, ii, 589
Permian of, ii, 634
Pliocene of, iii, 320
Proterozoic of, ii, 215
Triassic of, iii, 37
Asiderites, i, 661
Asiminia triloba, iii, 491
Asphalt, i, 460
in Texas, iii, 116
Astarte, iii, 295, 403
thomasii, iii, 292
Asteroids, i, 661
Astoria beds, iii, 248
Astraeospongia meniscus, ii, 403,
408
Astral eon, ii, 83, 90
Astresius liratus, iii, 136
Astrohelia, iii, 294
Astronomic geology, i, i, 2
hypotheses of glacial climate,
iii, 426, 431
Astrophyllites, ii, 602
Mississippian, ii, 537
Astylospongia, ii, 408
praemorsa, ii, 403
Atane series, iii, 132
Atascadero formation, iii, 68,
577
Athens shale, iii, 549
Athyris, ii, 615
hannibalensis, ii, 521
lamellosa, ii, 525
spiriferoides, ii, 521
Atlantic and Gulf border, Coman-
chean of, iii, 108
Atlantic coast, Cretaceous of, iii,
137
Cretaceous faunas, iii, 187
Eocene of, iii, 198
Miocene of, iii, 258
Pleistocene of, iii, 447
Pliocene of, iii, 308
Atlantic coastal plain, i, 587
Atlantosaurus beds, iii, 119
position of, iii, 66
Atmosphere, i, 5
affected by life, i, 639, 640;
ii, "5
carbonation by, i, 43
changes in Permian period, ii,
660
chemical work of, i, 41-43
evaporation and precipitation,
i, So
fluctuations in composition, i,
639-644
geologic activity of, i, 6, 21-43
mass and extent, i, 6
mechanical work of, i, 21-41
nature of earliest, ii, 95
origin of, ii, 93
oxidation by, i, 42
thermal effects of, i, 7
Atmosphereless stage of earthr
ii, 92
Atmospheric carbonic acid gas,
ii, 662
Atmospheric difficulties of nebu-
lar hypothesis, ii, 86
Atmospheric electricity, i, 43, 52
Atmospheric gases, gathering of,
», 97
gravity and, ii, 96
molecular velocities of, ii, 97
Atmospheric hypotheses of gla-
cial climate, iii, 432
Atmospheric precipitation,
amount of, i, 51
Ataka formation, iii, 562
Atremata, ii, 356
Atrypa hystrix, ii, 478
reticularis, ii, 409, 453, 478
Atrypina imbricata, ii, 455
Aturia, iii, 294
beds, iii, 248
Atwood, W. W., cited, ii, 252; Hi,
335, 336, 470, 471
Aucellia, iii, 82, 91, 92, 134
brauni, iii, 92
crassicollis, iii, 136
mosquensis, iii, 83
pallosi, iii, 92
piochii varorata, iii, 136
Auchenia vicugna, iii, 234
Augite, i, 400, 429, 461
Augitite, i, 468
Augusta series, ii, 500, 501, 561 r<
Hi, 558
Aulocopina, ii, 408
Austin limestone, iii, 142, 143,,
189
Australia, Archean of, ii, 159
Cambrian of, ii, 272
Cambrian fossils of, ii, 300.
Cretaceous of, iii, 171
Devonian of, ii, 248
Eocene of, iii, 219
fauna of, i, 668
Jurassic of, iii, 78
Miocene of, iii, 280
Mississippian of, ii, 517
Pennsylvanian of, ii, 590
Permian glacial beds of, iiw
632
Pleistocene life of, iii, 501
Triassic of, iii, 38
Autoclastic rock, i, 444; ii, 204
Aux Vases sandstone, ii, 561
Avicula, iii, 91, 92
Aviculopecten carboniferous, ii,
616
occidentalis, ii, 616
Azoic eon, ii, 83
Babb, C. C., cited, i, 107
Babbitt, F. E., cited, iii, 516^
Backstrom, cited, ii, 216
Bacteria, Devonian, ii, 493
Baculites, iii, 187
grandis, iii, 189
Badito formation, iii, 206
Bad-lands, i, 93, 130; iii, 269
584
INDEX.
Badger Mountain, i, 231
Bagg, R. M., cited, iii, 242
Baiera, ii, 643'. iii. 40, i?3
virginiana, ii, 643
Bain, H. F., cited, i, 67, 474; ii.
337 502, 542, 548; i", 60,
144, 388, 391, 411, 414
Bala beds, ii, 342
Balaena, iii, 294
Balanus, iii, 294
Baldwin, S. P., cited, iii, 403
Ball, R.. cited iii, 426
Bangor limestone, iii, 551
Baraboo quartzite, ii, 206. 207
Barbadoes earth, i. 661
Barbatia, iii, 295
Barbour, E. H., cited, iii, 411
Barite, i, 461
Barker series, iii, 569
Barrande, J., cited, ii, 271, 341
Barren measures, ii, 558, 562;
iii, 560
Barrier beach, the, i, 356
Barrois, C., cited, ii, 448
Barron, J., (and Hume, W. F. j
cited, iii, 320
Bars, i, 181, 357
Barton, G. H., cited, iii, 362
Barus, C., cited i, 562, 563; ii, 8
Barycrinus hoveyi, ii, 525
Barytherium, iii, 284
Basalt, i, 417, 452, 466
Neocene, iii, 154
Basaltic columns, i, 417
Bascom, F., cited, ii, 214
JBas3-level, i, 60, 62, 82, 168
Cretaceous, i, 169
Kittatinny. i, 168
temporary, i, 84
Basement complex, i, 18
Bastin, E. S., cited, iii, 153,247,
375; (and Blackwelder, E.),
iii, 335
IBatesville sandstone, ii, 562 ; iii,
560
Batholiths, i, 500, 592
Archean, ii, 131
Batocrinus, ii, 522
Bayley, W. S., cited, ii, 149, 150,
176, 178, 179, 180
Bayou, i, 192
Bayou lakes, i, 193
Bays, origin of, i, 331, 332
Bays sandstone, ii, 316; iii, 548
Beach, the, i, 355
Beaches, Arkona, iii, 397
Belmore, iii, 397
Beadnell, H. J. L., cited, iii, 219;
(and Andrews, C. W.), iii,
284
Bear family, iii 289
Beaufort series of South Africa,
ii, 636
Beauxite, i, 461
Beaver limestone, iii, 550
Beck, R., cited, i, 474
Becker, G. F., cited, i, 474;
ii, 667; iii, 122, 219, 281,
320, 516
Becket gneiss, iii, 547
Bedford limestone, ii, 500, 503,
53i; "i, 556
shale, ii, 560; iii, 554
Beecher, C. E., cited, ii, 283, 348,
350, 378
Beede, J. W., cited, ii, 621
Beekmantown limestone, ii, 310
Beetles, Jurassic, iii, 105
Belemnitella, iii, 187
americana, iii, 189
Belemnites, iii, 134, 187
brevifonnis, iii, 91
densus, iii, 93
Early Jurassic, iii, 91
Jurassic, iii, 82
Middle Jurassic, iii, 91
paxillosus, iii, 93
Upper Jurassic, iii, 92
Belfast bed, ii, 554
Bellerophon antiquatus, ii, 2gg,
300
clausus, ii, 353
psrcarinatus, ii, 616
sublaevis, ii, 533
Bell, R., cited, iii, 368, 403
Belly River deposits, iii, 152,
178
Belmore beaches, iii, 397
Belt series, iii, 569
Bennettitales, iii, 39, 94
Bennettiteae, iii, 39
Benton formation, iii, 148, 558,
564. 570
Berea grit, ii, 500, 560; iii, 553,
554
Berghaus, H., cited, iii, 524
Bergschrund, i, 258
Bermuda earth, iii, 260
Bernardston series, iii, 546
Bersea, iii, 173
Bertin, cited, i, 323
Bertrand, M., (and Zurcher,)
cited, iii, 252
Beryl, i, 461
Betula, iii, 173
Betulites westi, var. subintegri-
folius, iii, 174
Beulah shale, iii, 566
Beyer, S. W., cited, ii, 542
Bibbins, A., (and Clark,) cited,
iii, in, 114
Bifidaria armifera, iii, 410
corticaria, iii, 410
muscorum, iii, 410
pentodon, iii, 410
Bigby limestone, iii, 552
Bighorn mountains, lateral mo-
raines in, i, 302
Billings, E., cited, ii, 208
Billingsella coloradoensis, ii, 299,
300
transversa, ii, 285
Bilobites variens, ii, 455
Biotite, i, 400, 461
Birds, Cretaceous, iii, 179, 182
Eocene, iii, 240
Jurassic, iii, 102
Miocene, iii, 290
Bird's-eye limestone, ii, 314
Birge, E. A., cited, ii, 668
Bisbee group, iii, 575
Bischoff, Gustav, cited, i, 108
Bismuth, i, 461
Bison, Miocene, iii, 286
Pleistocene, iii, 491
Bittei Creek group, iii, 208, 213
" Bittern," i, 377
Bitumen, i, 461
in Texas, iii, 116
Bituminous coal, i, 426, 468
Biwabik formation, ii, 189
Black Hand conglomerate, ii,
500, 560; iii, 554
Black Hills, Cretaceous of, iii,
148
Proterozoic of, ii, 206
section of strata in, iii, 566
Black River limestone, ii, 310, 314
Blackrock diabase, iii, 546
Blackwelder, E., cited, ii, 250,
273, 300; iii, 469; (and
Bastin), iii, 335; (and Gar-
rey), iii, 334
Blake, W. P., cited, i, 474; ii,
224, 435, 552; iii, 516
Blanford, W. T., cited, i, 28, 203;
(and Medlicott), iii, 171
Blastoidea, Osage, ii, 525
Silurian, ii, 400, 403
Blatchley, W. S., (and Ashley,)
cited, ii, 424, 620; iii, 556
Blood-rain, i, 25
Blowing Rock gneiss, ii, 152
Blue mud, i, 380
Bluefield shale, ii, 559
Bluestone formation, ii, 559
Bluff formation, iii, 407
Bode's law, ii, 80
Body-deformations of continen-
tal borders, iii, 526
Boggy shale, iii, 562
Bohemia, Cretaceous, Upper, iii,
167
Oligocene of, iii, 251
Ordovician of, ii, 341
Permian of, ii, 627
Bohnerz formation, iii, 252
Bolboden, ii, 650
Bolsa quartzite, iii, 575
Bone beds, i, 663
Bonneville shore, i, 352
Boone chert, ii, 562; iii, 560
Boothia, Ordovician of, ii, 342
Borneo, Cretaceous of, iii, 172
Jurassic of, iii, 78
Pliocene of, iii, 320
Bornia, Mississippian, ii, 537
Bothriolepis, ii, 485
Botriopygus alabamensis, iii, 189
Bottom-set beds, i, 202
Bouve", J. J., cited, iii, 37O
Bowlder-clay, iii, 341
Bowlders, i, 468
of drift, iii, 340
Bozeman formation, iii, 157,267
Brachiopods, Cambrian, ii, 285,
297
Carboniferous, ii, 615, 616
Chemung, ii, 478
Devonian, ii, 464, 470
INDEX.
585
Brachiopods, Genevieve, ii, 53i»
532
geologic contributions of, i,
662
Helderbergian, ii, 454
Jurassic, iii, 85, 93
Kinderhook, ii, 519, 520
Middle Cambrian, ii, 299
Middle Jurass'c, iii, 91
Mississippian, ii, 523
Ordovician, ii, 355, 356
Oriskany, h, 458, 459
Osage, ii, 525
Permian, ii, 653
Silurian, ii, 401, 403
Triassic, iii, 53
Upper Cambrian, ii, 299, 300
Upper Devonian, ii, 476
Waverly, ii, 527
Brachiosaurus, iii, 98
Brachiospongia digitata, ii, 363
Brachyphyllum, iii, 39
yorkense, iii, 41
Brachyura, iii, 85
Brahmaputra delta, i, 203
Brainard, E., (and Seeley.) cited,
ii, 364
Bramatherium, iii, 323
Branchiosauria, ii, 607
Brar.don formation, iii, 261
Branner, J. C., cited, i, 489;
ii, 335, 562; iii, 219, 560
Branson, E. B., cited, ii, 624;
iii, 26
Braxton formation, iii, 548
Breakers, i, 341
force of, i, 344
Breccia, i, 423, 434, 468
Breviarca, iii, 187
Brxeville shale, iii, 549
Br.dger stage of Eocene, iii, 208
Brldgeton formation, iii, 449,
450
Brinfhid fibrolite-schist, iii, 546
Br'.tannare, i, 459
British Columbia, Eocene of, iii,
203
Miocene of, iii, 270
overthrust fault of, iii, 165
Pliocene of, iii, 315
Brittle-stars, Triassic, iii, 57
Broadhead, G. C., cited, iii, 411
Brogniart, C. H., cited, ii, 610
Bronteus lunatus, ii, 349
Brontops, iii, 255
Brontcsaurus, iii, 98, 99
Bronze age, iii, 504
Bronzite, i, 461
Brooks, A. H.. cited, ii, 213,436,
556; iii, 28,30, 203; (and
Taff, J. A.), 548
Brooks, W. K., cited, ii, 301
Brooksella alternata, ii, 287
Broom, R., cited, ii, 636, 650;
iii, 42, 43, 100
Brown, cited, ii, 605
Brown, B., cited, iii, 181
Brown shale, iii, 556
Browns Park group, iii, 209, 313
Brule clay, iii, 245, 564, 565
Brunswick formation, iii, 10
Bryophytes, Devonian, ii, 493
Bryozoan reefs, ii, 376
Bryozoans, Carboniferous, ii,
618
Devonian, ii, 467, 477
Genevieve, ii, 531, 532
Geologic contributions of, i,
662
Ordovician, ii, 357
Silurian, ii, 405 406
Triassic, iii, 57
Buchan, A., cited, iii, 434, 435
Buchanan gravels, iii, 383
Buckley, E. R., cited, i, 48, 50,
221; ii, 317
Buda limestone, iii, 117
Buell, I. M., cited, iii, 360
Buffaloes, Pleistocene, iii, 498
Buhrstone, i, 468
formation, iii, 199
Bulliops'.s, iii, 295
Bumastus trentonensis, ii, 349
Bunselurus, iii, 253
Bunter sandstone, iii, 32
Burlington beds, ii, 502
Burns lat'.te, iii, 572
Burnt coal, Wyoming, iii, 153
Burton (and Milne), cited, i, 636
Busycon, iii, 294
Buttes, i, 142
Bysmal'ths, i, 500, 592
Byssonychia radiata, ii, 354
Cacapor. sandstone, iii, 548
Cadoceras, iii, 92
Caelacanthus, ii, 614
Caenotheres, Miocene, iii, 284
Caenotheridae, iii, 236
Calamarians, Devonian, ii, 493
Calamites, ii, 596, 602
cistii, ii, 597
Devonian, ii, 494
Mississippian, ii, 537
Permian, ii, 642
Calamopitys, ii, 595
Calcareous springs, i, 235
tufa, i, 390
tufa in Lake Lahontan, iii,
464
Calciferous, fauna of, ii, 364
limestone, iii, 561
Calcimiric rocks, i, 458
Calcite, i, 461
Calcium bicarbonate, deposition
of, ii, 661
Calc-sinter, i, 468
Calhoun, F. H. H., cited, iii, 334,
357, 384
California, Eocene of, iii, 201
Miocene auriferous gravels of,
iii, 265, 299
oil of, iii, 201, 263
Pliocene of, iii, 310
section of strata in, iii, 577
Call, R. E., cited, iii, 302; (and
McGee, W J), iii, 411
Callicrinus murchisonianus, ii,
403
Callicystis jewetti, ii, 403
Calliostoma, iii, 295
philanthropus, iii, 294
Callipteridium, ii, 593, 595, 602
mansfieldi, ii, 614
membranaceum, ii, 614
Callipteris, ii, 595, 644, 646
conferta, ii, 643
Callopora pulchella, ii, 358
Caloosahatchie beds, iii, 308
Calumet and Hecla mine, tem-
perature in, i, 569
Calvin, S., cited, i, 88, 204, 373,
389: 11,337.424,432.501,
542; iii, 144, 149, 385, 386,
388, 390, 391, 406, 408, 41 1,
412, 516
Calvin sandstone, iii, 562
Calymene callicephala, ii, 349
niagarensis, ii, 403
Calyptraeidae, iii, 295
Camarotoechia barrandei, ii, 458
Cambrian, Alabama, ii, 247
animal life, ii, 279
anthozoa, ii, 286
Appalachian belt, ii, 254
Argentina, ii, 272
arthropoda, ii, 280
Australia, ii, 272
basis of subdivisions of, ii, 238
brachiopods, ii, 285, 297
changes in, since deposition, ii*
267
China, ii, 272
close of, ii, 269
ccelenterata, ii, 286
corals, ii, 287
Crustacea, ii, 283
echinodermata, ii, 286
European, igneous rocks of, iit,
272
faunas, foreign, ii, 299
succession of, ii, 294
sudden appearanc" of, ii, 301
foreign, ii, 270
fossils, Argentina, ii, 300
Australia, ii, 272
India, ii, 300
Tasmania, ii, 300
gastropods, ii, 297
Georgia, ii, 247
glacial beds in, ii, 272
graptolites, ii, 286
Great Britain, ii, 270
hydrozoa, ii, 286
igneous rocks, ii, 252, 272
India, ii, 272
life of, ii, 276
ecological adaptation, ii, 292
Massachusetts, ii, 265
Middle, brachiopods, ii, 298,
299
cystids, ii, 299
gastropods, ii, 298
trilobites, ii, 298
mollusca, ii, 283
molluscoidea, ii, 284
Newfoundland, ii, 244, 263
New York, ii, 247
North Atlantic, ii, 248
North Carolina, ii, 247
586
INDEX.
Cambrian, Northern New Jersey,
ii, 265
Ordovician and, separation of,
ii, 250
outcrops of, ii, 253
width of, ii, 256
Period, ii, 218
duration of, ii, 273
plants, ii, 278
protozoa, ii, 287
pteropods, ii, 298
Quebec, ii, 247
relation to Proterozoic, ii, 218
seas, spread of, ii, 229, 237
sections of, ii, 225, 263
sedimentation, ii, 246
sponges, ii, 287
stratigraphy and correlation,
ii, 239
subdivisions of, ii, 219
system, distribution of, ii, 252
outcrops of, ii, 252
thickness of, ii, 252
Tasmania, ii, 300
Ten Mile region, Colorado, ii,
264
Tennessee, ii, 247
Tintic region, Utah, ii, 267
trilobites, ii, 281, 297
Upper, annelids, ii, 299
brachiopods, ii, 299, 300
cephalopods, ii, 299
corals, ii, 299
cystids, ii, 299
gastropods, ii, 299, 300
limit of, ii, 243
pelecypods, ii, 299
trilobites ii, 299, 300
-vermes, ii, 286
Vermont, ii, 264
Wasatch mountains, ii, 266
Wisconsin, ii, 251
Camden chert, ii, 422
Camelidae, iii, 285
Camels, Eocene, iii, 236
Miocene, iii, 286
Camerata. Osage, ii, 522
Campbell, M. R., cited, i, 167,
171, 173; ", 254, 319, 434,
546, 557, 559, 56o; iii, 305
Campeloma harlowtonensis, iii,
134
Camphene, i, 646
Camptonectes bellistriata, iii, 92,
93
Camptosaurus, iii, 99
Canaan formation, ii, 503; Hi,
548
Canada, Archean of, ii, 146
Canadian system, ii, 310
Cancellaria, iii, 294
alternata, iii, 294
subalta, iii, 187
Caney shale, ii, 504, 511; iii,
562
Canidae, iii, 237
Canis, iii, 289
Cannel coal, i, 468
Canoe-shaped valleys, i, 155
Canyons, i, 94-100
Canyons, Colorado, i, 98, 233
Niagara, i, 99
Yellowstone, i, 100
Canyon series, ii, 563
Cape May formation, iii, 449,
45i
Capps, S. R., Jr., (and Leffing-
well.) cited, iii, 334
Carabocrinus vancortlandii, ii,
359
Caradoc beds, ii, 342
Carbon dioxide, a climatic factor
in Permian, ii, 661
amount in air, i, 5, 640
in Mississippian limestone,
ii, 661
and plant-life, i, 665
climatic effects of, i, 643; ii,
670
influence on plant growth, ii,
605
loss of , i, 640
of air and ocean, equilibrium
between, ii, 665
of atmosphere, effect on
mcisture, ii, 670
supply of, i, 618, 640
Carbonation, i, 43, 429
Carbonic acid gas and ocean, iii,
438
and temperature, ii, 667
as a thermal factor, iii, 444
of ocean, and agitation, ii, 667
Carboniferous (see also Pennsyl-
vanian)
brachiopods, ii, 615
bryozoans, ii, 618
cephalopods, ii, 615, 616
coral, ii, 616
crinoids, ii, 616, 617
ferns, ii, 593
fishes, ii, 613
flora, distribution of, ii, 601
fresh-water life, ii, 612, 614
gastropods, ii, 615, 616
igneous rocks, European, ii,
588
insects, ii, 610
land animals, ii, 606
land shells, ii, 614
marine life, ii, 613
mollusks, ii, 615
myriapods, ii, 6n
pelecypods ? ii, 615, 616
period, ii, 559
plants, ii, 501-606, 611
protozoa, ii, 616, 618
scorpions, ii, 611
spiders, ii, 611
terrestrial life, ii, 614
trilobites, ii, 6iC, 618
Carcharias, iii, 294
Carcharodon megalodon, iii, 294
Cardilia, iii, 295
Cardiocarpon, ii, 601
Cardiocarpus, Mississippian, ii,
537
Cardioceras, iii, 92
alterinous, iii, 92
cordiformis, iii, 93
Cardita, iii, 295
Cardium, iii, 293
leptopleurum, iii, 292
Carlile formation, iii. 566
Carlisle shale, iii, 155, 206
Carll, J. F., cited, i,i, 382
Carnivora, iii, 229
Miocene, iii, 284
Ollgocene, iii, 253
Pliocene, iii, 322, 323
Carolina gneiss, ii. 152
Carson shale, iii, 560
Carters limestone, iii, 552
Caryatis veta, iii, 189
Caryocr-nus ornatus, ii, 403
Cascade, i, 264
Cascade formation, iii, 120
Case, E. C., cited, ii, 620
Cassidaria, iii, 295
Cass'dul'ma, iii, 294
Cassiiulus, iii, 189
subquadratus, iii, 189
Cassis, iii, 295
Cassiterite, i, 461
Catheys formation, iii, 552
Catlinite, i, 461
Catazyga headi, ii, 356
Catskill formation, ii, 433
Cauda Galli grit, ii, 424
Causes of crustal movement, i,
551-57
Caverns (see Caves)
Caves, i, 143, 227-231
deposits in, i, 228; iii, 488
Mammoth, i, 227
sea, i, 350
Wyandotte, i, 227
Cayugan series, ii, 370
Cazin, F. M. F., cited, i, 474
Cedar Valley limestone, iii, 558
Cementation, effected through
chemical precipitation, i,
222, 225, 226
effected through evaporation, i,
42
Cenomanian epoch, map, iii, 169
Cenozoic Era, iii. 191
Central America, Eocene of, iii,
220
Jurassic of, iii, 78
Oligocene of, iii, 244, 252
Pennsylvanian of, ii, 591
Central compression, heat from,
ii, 101
Cephalaspis, ii, 482, 483, 485
Cephalopods, Cambrian, ii, 283
Carboniferous, ii, 615, 616
Comanchean, iii, 136
Cretaceous, iii, 187, 188
Devonian, ii, 465, 477
Genevieve, ii, 532, 533
geologic contributions of, i,
662
Helderbergian, ii, 454
Jurassic, iii, 93
Kinderhook, ii, 520, 521
Middle Jurassic, iii, 91
Miocene, iii, 294
Mississippian, ii, 525
Ordovician, ii, 352
INDEX.
587
Cephalopods, Permian, ii, 653,
654
Silurian, ii, 403, 405
Triassic, iii, 51, 53, 56
Upper Cambrian, ii, 299
Upper Jurassic, iii, 91
Cerastoderma, iii, 292
Ceratiocarids, Silurianv ii, 408
Ceratites, iii, 52
binodosus, iii, 54
nodosus, iii, 51
Triassic, iii, 52, 54, 56
trlnodosus, iii, 54
whitneyi, iii, 53
Ceratodus, ii, 487
Ceratopsis chambers!, ii, 351
Ceratops family, iii, 176
oculifera, ii, 351
Ceratosaurus nasicornis, iii, 97,
08
Ceraurus pleurexanthemus, ii,
349
Cercopithecidae, iii, 324
Cerlthium paskentsensis, iii, 136
texanum, iii, 135
Cervidae, iii, 256
Cetacea, iii, 229
Miocene, iii, 294
Cetiosaurus, iii, 99
Chadron formation, iii, 245, 564,
565
Chain coral, Silurian, ii, 407
Chalcedony, i, 461
Chalk, i, 468, 660
Comanchean, iii, 117
Cretaceous, iii, 143
European, iii, 169
origin of, iii, 149, 186
Challenger deep, i, 587, 588
Chalmers, R., cited, iii, 336, 361
Chalybeate springs, i, 235
Chamberlain shale, iii, 269
Chamberlin, R. T., cited, ii, 95;
iii, 470
Chamberlin, T. C., cited, i, 23,
242, 256, 322, 477, 565,
668; ii, 198, 302, 323, 337,
414,613; Hi, 337, 344, 36i,
367, 370, 412, 516; (and
Lever ett), iii, 382; (and
Salisbury), iii, 344, 411
Chamidae, iii, 134
Champlain clays, iii, 403
epoch, iii, 494
sub-stage, iii, 403
Champlainic system, ii, 310
Champsosaurus, iii, 181
Chance, H. M., cited, iii, 382
Changes of level, i, 537-551
caused by earthquakes, i, 536
causes of, 551-557
effect on drainage, i, 161
Pleistocene, iii, 480
sea versus land, i, 538
Changes of temperature, condi-
tions affecting, i, 45
effect on rocks, i, 44, 49
internal (see Internal tem-
peratures)
Chapin, J. H., cited, iii, 370
Charleston earthquake, i, 530
sandstone, ii, 559
Chattahoochee beds, iii, 244
Chattanooga shale, iii, 549, 551
552
Chatter-marks, i, 284
Chautauquan series, ii, 433
Chazy fauna, ii, 365
limestone, ii, 310
Cheiracanthus, ii, 490
Cheirolepis, iii, 40
muensteri, iii, 41
trailii, ii, 489
Cheiroptera, iii, 229
Chelonia, iii, 42
Triassic, iii, 43
Chelyzoon, iii, 44
Chemical combination, cause of
crustal movement, i, 556
Chemical deposits, i, 222-226
in deep sea, i, 383
in lakes, i, 391
in shallow sea, i, 374-378
Chemical work of atmosphere, i,
41-43
Chemical work of life, i, 638-
646
Chemnitzia, iii, 91
Chemung brachiopods, ii, 478
fauna, ii, 477
formation, ii, 433
gastropods, ii, 478
pelecypods, ii, 478
pteropods, ii, 478
Chert, i, 426, 468
Chesapeake fauna, iii, 291
formation, iii, 260, 449
Chester amphibolite, iii, 546
beds, ii, 500, 503
Cherokee shales, ii, 561
Cheyenne sandstone, iii, 118
Chiastolite, i, 461
Chickahoc chert, iii, 562
Chickamauga limestone, ii, 316;
iii, 548, 55i
Chickasawan formation, iii, 199
Chico series, iii, 160
Chicopee shale, iii, 546
Chillesford Crag, iii, 318
Chilonyx, ii, 650
Chimaeridas, iii, 85
Chimney-rocks, i, 350
Chimpanzee, iii, 326
China, Archean of, ii, 159
Cambrian of, ii, 272, 273
coal of, ii, 590
Cretaceous, Upper, iii, 170
Devonian of, ii, 448
Eocene of, iii, 217
loess of, iii, 407
Mississippian of, ii, 517
Pennsylvanian of, ii, 590
Chipola beds, iii, 244
Chlamys, iii, 292
Chlorite, i, 461
Chlorite schist, i, 468
Chloritic rock, i, 431
Chonetes, ii, 465, 615
cornutus, ii, 403, 471, 472
granulifera, ii, 617
Chordata, ii, 484
Choristoceras marshi, iii, 51
Choristodera, iii, 181
Chouteau limestone, ii, 500, 561
Chromite, i, 461
Chrysodomus, iii, 294
decemccstatus, iii, 294
Chrysolite, i, 462
Chrysotile, i, 462
Chuar formation, ii, 153 ; iii, 574.
Church, A. P., cited, iii, 342, 473
Cidaris, iii, 91
coronata, iii, 84
Cidaroida, iii, 85
Cincinnati arch, ii, 330, 335
Cincinnatian series, ii, 310
Cinder-cones, i, 608
Cinders, i, 405
Cinnamomium, iii, 173
Cintura formation, iii, 575
Circularity of orbits, evolution of
ii, 67
Cirques, i, 286
in Uinta mountains, iii, 467
Cisco series, ii, 563
Civet family, iii, 289
Cladodoxylon, ii, 595
Cladodus, ii, 536
springeri, ii, 521
Cladoselache, ii, 536
Claibornian formation, iii, 199
Claosaurus, iii, 178
Clark, W. B., cited, ii, 319; iii.
59, 114, 137, 139, 140, 242,
260, 261 ; (and Bibbins), iii
in, 114; (and Martin), iii,
198
Clarke, F. W., cited, i, 396, 573
Clarke, J. M., cited. ii,39i, 451,
478; (and Schuchert), 310,
370, 420
Clarke, W., (and Lewis,) cited,
i", 153
Clark formation, ii, 559
Clarksburg formation, ii, 186,
187
Clarno beds, iii, 210
Classification, geological, basi»
of, iii, 192
of rocks, i, 449
new system of, i, 451
Clastic rock, i, 468
Clay, i, 468
Clay ironstone, i, 468
Claypole.E. W., cited, i, 549; ii,
425
Clays, Champlain, iii, 403
Clayton formation, iii, 199
Clear Fork formation, ii, 623
Cleavage planes and erosion, i,
125
development of (see Slate and
Schist)
Clements, T. M., cited, ii, 150,
151, 180, 194
Clepsydrops, ii, 649
Cliff glacier, i, 256
Clifton limestone, iii, 552
Climacograptus bicornis, ii,
362
588
INDEX.
Climate, Cambrian, ii 273
Comanchean, iii, 129
Cretaceous, iii, 161, 172
Early Cretaceous, iii, 129
Glacial, hypotheses of, iii, 424
influence on erosion, i, 127-
132
Jurassic, iii, 79
Miocene, iii, 261, 281
Mississippian, ii, 518
Ordovician, ii, 342
Permian, ii, 669
post-Pliocene elevation and,
iii, 316
Salina, ii, 387
Silurian, ii, 396
Climatic conditions of Trias, iii,
29
Climatic effects of carbon di-
oxide, i, 643
of life, i, 643
of water vapor, i, 643
Climatius, ii, 490
scutiger, ii, 490
Clinch sandstone, iii, 548
Clinkstone, i, 468
Clinocerasmuiniaeforme, ii,352
Clinometer, i, 501
Clinton formation, ii, 370, 375
iron ore of, ii, 377
Clinton limestone, iii, 554, 556
Clitambonites anomala, ii, 356
Clypeaster, iii, 294
Coal, i, 468
Alaska, map of, in, 203
Arizona, ii, 552
burnt, of Wyoming, iii, 153
China, ii, 590
Colorado, iii, 159
Comanchean, iii, 124
composition of, ii, 570
Cretaceous, iii, 159
Eocene, iii, 202
European, thickness of, ii,
585
Great Britain, ii, 586
Jurassic, iii, 78
Lias, iii, 73
Middle Jurassic of England,
iii, 73
Narragansett basin, ii, 549
New Mexico, ii, 552
Newark, iii, 4
occurrence of, ii, 517
Oligocene, in Europe, iii, 25
origin of, ii, 564, 565
Pennsylvania, ii, 627
Richmond, iii, 40
Triassic, iii, 4
of Virginia, iii, 17
Coal-bearing shale, ii, 562
Coal-beds, European, ii, 585
faulted, ii, 580
history of, ii, 571
number of, ii, 572
Rhine basin, ii, 587
Russia, ii, 587
Coaledo formation, iii, 202,
203
Coal-field, Donetz, ii, 515
Eastern Interior, ii, 548
Moscow, ii, 515
Northern Interior, ii, 548
Western Interior, ii, 548
Coal-fields, productive, ii, 546,
547
Coal flora, ii, 591
Coal formation, effect on atmos-
sphere, ii, 664
Coal Measures, ii, 541
African, ii, 590
Asian, ii, 589
Australian, ii, 590
Central American, ii, 591
European, deformation of, ii,
588, 589
European, thickness of, ii, 588
New Zealand, ii, 590
section of, ii, 550
South American, ii, 591
thickness of, ii, 582
unconformities in, ii, 574
Coal Period, ii, 539 (see also
Pennsylvanian )
duration of, ii, 582
Coal plants, climatic implications
of ii, 603
varieties of, ii, 576
Coast-lines, i, 353, 363-366
effect of gradation on, i, 333,
363
effect of subsidence on, i, 329,
332
effect of vulcanism on, i, 332-
33
forms of, i, 329, 333, 363, 364
Coast ranges, crustal shorten ng
due to folding of. i, 549
Coastal Plain, Pleistocene of, iii,
447
Coasts, natural bridges on, i,
35i
Cobb, C., cited, i, 36
Cobleskill limestone, ii, 370, 389
Coccosteus deciplens, ii, 487
Cochran formation, iii, 550
Ccelacanthidae, iii, 86
Coslenterata, Cambrian, ii, 286
Devonian, ii, 456, 463, 470,
476
geologic contribution of, i, 661
Mississippian, i, 521, 523, 530
Ordovician, ii, 360, 361
Silurian, ii, 407
Coldwater shales, iii, 553
Coleman, A. P., cited, ii, 151 , 181 ;
iii, 482, 490, 491
Collier, A. J., cited, ii, 390
Collins, A. L., cited, i, 474
Collision, origin of nebulae by,
ii, 21
of planetesimals, ii, 66, 72
of stars, ii, 53
Colodon, iii, 253
Colorado, Canyon of, i, 98, 233;
iii, 312
coal, iii, 159
sections of strata in, iii, 570,
572
Colorado series, iii, 72, 142, 148,
155, 157. 166, 568
Columbia formation, iii, 447, 450
fossils of, iii, 451
origin of, iii, 452
stratigraphic relations, iii, 451
Columbia river, i, 171
Columbus limestone, iii, 554
Columnar structure, i, 498-500
effect on weathering, i, 153,
154
Columnarla alicolata, ii, 361
Comanchean cephalopods, 111,136
corals, iii, 135
echinoids, iii, 135
fauna of Texas, iii, 135
fresh-water fauna, iii, 134
gastropods, iii, 134, 135, 136
land-animals, iii, 133
marine faunas, iii, 134
pelecypods, iii, 134, 135, 136
Comanchean period, iii, 106
climate of, iii, 129
close of, iii, 124
distinct from Upper Creta-
ceous, iii, 125
life of iii, 130
terrestrial vegetation of, iii,
130
Comanchean system, iii, 107,
108, no
Atlantic and Gulf border, .ii,
1 08
Arizona, iii, 117
chalk of, iii, 117
coal of, iii, 124
Mexico, iii, 118
north of United States, iii, 123
northern interior, iii, 119
Pacific border, iii, 122
Panama, iii, 124
Texas, iii, 115
Comarocystis punctatus, ii,
359
Comets and meteorites, relations
of, ii, 36
Common springs, i, 235
Como beds, iii, 97, 119 (see also
Morrison)
position of, iii, 66
Compression joints, i, 514
Compsacanthus, ii, 614
Compsognathus, iii, 97
Comstock, T. B., cited, ii, 221,
265
Concave tracts of crust, i, 585,
586
Concretions, i, 438, 468, 490
loess, iii, 409
Condon, T., cited, iii, 310
Condylarthra, iii, 224, 229
Conemaugh series, ii, 542, 557
560; iii, 554
Cones, cinder, i, 608
composite, i, 610
formation of, i, 608
geyser, i, 237
lava, i, 608
spatter, i, 610
tufa, i, 6n
INDEX.
589
Configuration of coasts, i, 329,
330, 33L 332, 333. 353,
363-6
Conformability, i, 15
Congeria, iii, 295
Conglomerate, i, 423, 434. 468,
487 ; iii, 4
Conifers. Carboniferous, li, 601
Jurassic, iii, 94
Triassic, iii, 39, 41
Conocardium.Onondagan.ii, 467
meekanum, ii, 533
prattenarum, ii, 533
trigonale, ii, 463
Conocoryphe, ii, 299
Conosauga formation, iii, 551
Conradella fimbriata, ii, 353
Constellaria polystomella, ii, 358
Continental borders, behavior of,
iii, 526
body-deformation of, iii, 526
geological record on, iii, 523
Continental borders and crustal
movements, iii, 526
and ice-sheets, iii, 529
Continental creep, ii, 131
Continental and oceanic seg-
ments, ii, 123, 235
glaciers, i, 251
platforms, i, ii
origin of, ii, 107-111
relief of, i, n
segments, size of, i, 547
shelf, i, ii
Continent-forming movements, i,
544
Contour interval, i, 31
Contour lines, i, 31
Conularia, ii, 459, 473, 478
Silurian, ii, 407
trentonensis, ii, 353
Conus diluvianus, iii, 294
Convection hypothesis, internal
heat on, i, 559
thermal distribution on, i, 559
Conway schist, iii, 546
Conybeare, W. D., cited, iii, 89
Cook, G. H., cited, iii, 14, 113,
370; (and Smock), 367
Cooley, E. G., cited, i, 195
Coon Butte, i, 596
Cooper formation, iii, 199
Cooper River marl, iii, 242
Copalite, i, 646
Cope, E. D., cited, iii, 210, 228,
230, 235
Copper, Keweenawan, ii, 198
Lake Superior, ii, 198
Permian, ii, 629, 630
Coprolites, i, 646
Coquina, i, 469
Coral mud, i, 380
Coral Rag formation, iii, 83
Coral reefs, ii, 414
Silurian, ii, 407
Corallian epoch, iii, 83
Coralline crag, iii, 318
Corals, Cambrian, ii, 287
Carboniferous, ii, 616
Comanchean, iii, 135
Corals, Devonian, ii, 463, 470
Genevieve, ii, 530
Hamilton, ii, 470
Helderbergian, ii, 456, 457
Jurassic, iii, 83, 84, 94
Kinderhook, ii, 520, 521
Miocene, iii, 294
Mississippian, ii, 523
Onondagan, ii, 463
Ordovician, ii, 360, 361
Oriskany, ii, 459
Osage, ii, 523
Silurian, ii, 406, 407
Triassic, iii, 57
Upper Cambrian, ii, 299
Upper Jurassic, iii, 91
Corbin conglomerate, ii, 560
Corbula, iii, 295
aldrichi, iii, 243
blakei, iii, 53
idonea, iii, 292
persulcata, iii, 136
Cordaites, ii, 600, 602
borassifolius, ii, 602
Carboniferous, ii, 600
Devonian, ii, 493
Mississippian, ii, 537
Permian, ii, 645
Triassic, iii, 39
Cordianthus sp., ii, 594
Cordilleran ice-sheet, iii, 330, 332
Cordilleran region, Proterozoic
of, ii, 209
Corniferous formation, ii, 426;
iii, 556
Cornish, V., cited, i, 26, 28, 29
Cornua, ii, 484
Cornus, iii, 173
Coroniceras (Arietes) bisulca-
tum, iii, 81
claytoni, iii, 91
Cornwallis, Ordovician of, ii, 342
Corrasion, i, no, 113
by glaciers, i, 281-286
by streams, i, 119
by waves, i, 342-349
by wind, i, 38
effect of sediment on, i, 120
Corstophine, G. S., cited, iii, 129
Corthell, E. L., cited, i, 202
Corymbocrinus, ii, 411
Coryphodon beds, iii, 208
hamatus, iii, 233, 234
Cosmopolitan development of
Ordovician life, ii, 343
Cosmopolitan faunas, i, 668
Cosmopolitanism, human, iii,
540
Cottonwood limestone, iii, 564
Cotylosauria, ii, 648, 650
Coulter, J. M., cited, 1,667; iii,
39
Coves, i, 143
Cowles, H. C., cited, i, 35, 667
Cragin, F. W., cited, ii, 621, 623 ;
iii, 60, 118
Cranberry granite, ii, 152
Crania Icelia, ii, 356
Silurian, ii, 404
Crassatella delawarensis, iii, 189
Crassatellites. iii, 295
alaeformis, iii, 243
marylandicus, iii, 292
Crassinella, iii, 295
Crazy Mountains, igneous rocks
in, iii, 168
Credner.H., cited, i, 35, 538; ii,
270
Creep, i, 231
continental, iii, 312, 526
Creodonta, iii, 229, 284
Eocene, iii, 236
Crepicephalus, ii, 299
texanus, ii, 299
Crepidula fornicata, ill, 294
Crepipora hemispherica, ii, 358
Crested Butte region, ii, 154
Cretaceous ammonites, iii, 187,.
190
base-level, i, 169
birds, iii, 179, 182
cephalopods, iii, 187, 188
crocodiles, iii, 178
dinosaurs, iii, 176
dolichosaurs, iii, 180
fauna of interior, iii, 190
of Pacific coast, iii, 190
fishes, iii, 185
flora, general aspect of, iii»
175
foraminifers, iii, 186
gastropods, iii, .187, 190
gavials, iii, 179
ginkgo, iii, 173
glauconite. iii, 139
grasses, iii, 173
greensand, iii, 186
greensand marl, iii, 139
gymnosperms. iii, 173
ichthyosaurs, iii, 180
land animals, iii, 175
lizards, iii, 178
mammals, iii, 179
monocotyledons, iii, 173
mosasaurians, iii, 180
palms, iii, 173
pelecypods, iii, 187, 190
Cretaceous period, iii, 137
Atlantic coast, faunas of, iii,
187
climate of, iii, 161, 172
close of, iii, 161
crustal movements at close of,
iii, 162
Early, climate of, iii, 129
Early, close, of iii, 130
faulting at close of, iii, 164
igneous eruptions during, iii,
167
knd life of, iii, 172
life, of iii, 172
marine life of, iii, 180
plant life of. iii, 173
plants of Dakota horizon, iii,
174
plesiosaurs, iii, 180
pterosaurs, iii, 179
pythonomorphs, iii, 180
rhizopods, iii, 186
rhynchocephalians, iii, 181
590
INDEX.
Cretaceous period, salamanders,
iii, 179
saurians, iii, 180
sea-turtles, iii, 180
sea-urchins, iii, 186
sequoias, iii, 173
snakes, iii, 178
special faunas of, iii, 187
Cretaceous system, Africa, ii5, 171
Asia, iii, 170
Atlantic coast, iii, 137
thickness of, iii, 140
Australia, iii, 171
Black Hills, iii, 148
Borneo, iii, 172
chalk of, iii, 143
coal of, iii, 159
Europe, iii, 167
iron ore in, iii, 170
Gulf coast, iii, 140
Lower, Africa, iii, 129
Asia, iii, 129
Europe, iii, 126, 128
iron ore in, iii, 128
foreign, iii, 125
South America, iii, 129
map of, iii, 138
New Zealand, iii, 172
outside of America, iii, 167
Pacific coast, iii, 160
South America, iii, 171
Texas, thickness of, iii, 143
thickness of, iii, 160
western Gulf border, iii, 142
western Interior, iii, 144
Cretaceous teleosts, iii, 185
turtles, iii, 178
Crevasses, i, 264
Crinoid curve, ii, 526
Crinoids, i, 661
Carboniferous, ii, 616, 617
Devonian, ii, 464, 470
Genevieve, ii, 530, 532
Helderbergian, ii, 456
Jurassic, iii, 83, 84
Kinderhook, ii, 519, 520
Ordovician, ii, 359
Oriskany, ii, 459
Osage, ii, 522, 525
Silurian, ii, 400, 403
Triassic, iii, 57
Waverly, ii, 527
Crioceras, iii, 134
Cristellaria gibba, ii;., 241
radiata, iii, 241
Criteria of glaciation, iii, 337
Croatan beds, iii, 308
Crocodiles, iii, 42
Cretaceous, iii, 178
Jurassic, iii, 100
Triassic, iii, 43
Croll, James, cited, i, 322, 323,
339; ii, 21 ; iii, 426, 519
Croll's hypothesis of glacial cli-
mate, iii, 426
Crosby, W, O., cited, i, 513; iii,
370
Cross, W., cited i, 412, 451, 535,
573; ii, 624; iii 27, 65, 119,
156, 158, 474J (and Em-
mons and Eldridge), iii,
570; (and Howe), iii. 572
Cross-bedding, i, 373, 487
Cross-currents, in streams, \, 117
Crossopterygians, ii, 487
Devonian, n, 461
Crotalocnnus ii, 410
pulcher, ii, 403
Croton river, material in solu-
tion in, i, 108
Crowley's Ridge, iii, 408
Crushing strength of rock, ii, 127
Crust of earth, i, 13
depth of, i, 14
on Laplacean hypothesis, ii, 7
varieties of rock in, i, 14
Crustacea, Cambrian, ii, 283
Devonian, ii, 456, 459, 467,
471
Early Jurassic, iii, 91
Jurassic, iii, 85
Miocene, iii, 294
Mississippian, ii, 521, 533
Ordovician, ii, 348
Pennsylvanian, ii, 618
Silurian ii, 408
Crustal adjustments, ii, 237
due to easing of stresses, ii, 237
due to gradation, ii, 236
due to thermal changes, ii, 237
Crustal movements, i, 526-589
causes of, i, 551-557
differential extent of, i, 548
due tc chemical change, i, 556
due to cohesion and crystal-
lization, i, 554
due to diffusion, i, 555
earthquake, i, 527-533
minute and rapid, i, 526
periodicity of, i, 517, 539
resistance to, i, 557
slow and massive, i, 537~559
Crustal movements and conti-
nental borders, iii, 526
Crustal shortening, i, 548, 549»
550, 55i
Cryphaeus boothi, ii, 47 1
Cryptomeria, ii, 645
Cryptonella, ii, 465, 472
Crystal Falls region, Huronian
series of, ii, 180
Crystalline rocks, types of, i, 16
Crystallites, i, 407
Crystallization of lava, i, 401,
402
stages of, i, 403
Crystals, enlargement of, i, 435
Ctenodonta nasuta, ii? 354
pectunculoides, ii, 354
recurva, ii, 354
Ctenodus, ii, 537, 614
Ctenophyllum, iii, 39
Ctenostreon, iii, 91
Cuba, Jurassic of, iii, 60
Cuboides zone, ii, 475
Cuchara formation, iii, 153, 206,
208
Culm formation, ii, 513
Cummins, W. F., cited, ii, 563,
623
Cup coral, Silurian, ii, 407
Cushing, H. P., cited, ii, 203
Cut-and-fill, i, 190, 193
Cut-off, i, 191
Cutler formation, iii, 572
Cuttlefishes, Jurassic, iii, 82
Cuyahoga shale, ii, 500, 560;
i", 554
Cyathaspis, ii, 483, 484
Cycadales, iii, 39, 94
Cycadeae, iii, 39
Cycadeans, Triassic, iii, 39, 41
Cycadeoidea dakotensis, iii, 131
emmonsi, iii, 41
Cycadeomyelon, iii, 39
Cycadeospermum wanner i, iii, 41
Cycadofilices, ii, 593
Devonian, ii, 493
Mississippian, ii, 537
Pennsylvanian, ii, 592, 593,
595
Permian, ii, 644
Cycads, Carboniferous, ii, 601
Triassic, iii, 39
Cycas, iii, 39, 173
Cycle of erosion,
definition of , i, 82
recognition of, i, 164
stages of, i, 80
Cyclonema bilix, ii, 353
Cyclostomes, ii, 486
Cylichnina, iii, 294
Cymoglossa, ii, 644
obtusifolia, ii, 643
Cynodesmus, iii, 253
Cynodictis, iii, 253
Cynognathus crateronotus, ii,
651
Cypraea, iii, 295
Cyphaspis christyi, ii, 403
Cypricardella bellistriatus, ii, 471
Cyprimeria, iii, 134, 187
Cyprina, iii, 134
Cyrtina, ii, 465
acutirostris, ii, 520, 521
dalmani, ii, 455
hamiltonensis, ii, 462, 478,
52i
Cyrtoceras, ii, 473
Onondagan, ii, 466
Cyrtoceras neleus, ii, 352
Cyrtolites ornatus, ii, 353
Cystids, i, 66 1
Devonian, ii, 459, 464, 470
Genevieve, ii, 530
Helderbergian, ii, 456
Middle Cambrian, ii, 299
Ordovician, ii, 357
Silurian, ii, 403
Upper Cambrian, ii, 299
Dacite, i, 469
Dadoxylon, ii. 601
Daedicurus clavicaudatus, iii, 501
Dakota formation, iii, 68, 69, 70,
142, 144, 153, 155, 157, 166,
206, 558, 564, 565, 566, 568,
570
Hogback, iii, 146
horizon, plants from, iii, 174
INDEX.
591
Dakoto province, Jurassic fauna
of, in, 93
Dale, T. N., cited, i, 505
Dall, W, H., cited, in, 195, 196,
199, 200, 203, 205, 242,
247, 248, 257, 266, 291,
308, 310. 31 1 , 495, 522 ; (and
Harris), 258, 261, 262, 309
Dalmanella elegantula, h, 409
subcarinata, ii, 455
testudinaria, ii, 356, 367
Dalmanites, ii, 467, 473
Daly, R. A., cited, i, 631
Dana, J. D., cited, i, 203, 340,
349- 5", 543, 604. 636;
11,82,258,336,538; in, 54.
93, 150. 164, 192, 261, 361,
370, 403, 424
Danian epoch, iii, 170
Daniell, A., cited, i, 572, 573
Danube river, delta of, i, 202
material in solution in, i, 108
sediment carried by, i, 107
Daphaenus, iii, 253
Darton.N. H., cited, i, 41, 50, 53,
94, 135, 154, 494, 57o; ii,
254, 437, 505, 506, 521 ; iii,
14, 16, 25, 64, 119, 146, 149,
151, 245, 246, 269, 270, 271,
300, 449, 452, 454, 548, 564,
566; (and Smith), 66, 68,
I2O, 121, 566
Darwin, C., cited, i, 604, 636, 665
Darwin, G. H., cited, i, 534, 561,
576,579,583,604; ii, 6, xi,
14, 18, 40
Daubree, G. A., cited, i, 626
Davenport beds, iii, 558
David, W. E., cited, ii, 159, 273,
6^?, 6'^
Davidson, G., cited, iii, 522
Davis, B. M., cited, i, 225
Davis, C. A., cited, i, 655
Davis, W. M., cited, i, 83, 159,
164, 170, 188, 202, 204, 210,
349; (and Shaler, N. S.)»
256; Hi, 10, ii, 13,36,194,
205, 275, 305, 313, 370, 373,
403, 4"
Davison, C., cited, i, 527, 538,
56i
Dawson, G. M., cited, ii, 250, 257,
308, 390, 435, 506, 507,
510,555,556,624; iii, 14,
27, 28,30,61,120, 123, 145,
152, 161, 163, 164, 203, 248,
270, 316, 332, 367, 403
Dawson, J. W., cited, ii, 346, 495,
610; iii, 231, 336, 403
Deadwood limestone, iii, 267
Deadwood sandstone, iii, 68
Dean, B., cited, ii, 534
De Beaumont, Elie, cited, i, 323
Decapods, Jurassic, iii, 85
Decarbonation, i, 429, 430
Deccan igneous rocks of, iii, 171
De Charpentier, ].„ cited, i, 321,
322, 323
Deeley, R. M., cited, i, 322
Deep-sea circulation, iii, 441
Deep-sea deposits, i, 368, 378-
386
chemical, i, 383-386
extra-terrestrial, i, 381
inorganic, i, 380
manganiferous, i, 384
organic, i, 382
Deep-sea fauna, i, 670
Deer, Miocene, iii, 285
Pliocene, iii, 322
Deformation, continental bor-
ders, iii, 526
Miocene, iii, 273
modes of, under Laplacian
hypothesis, ii, 125
under planetesimal hypothe-
sis, ii, 117, 122
Permian, ii, 656
Pleistocene, end of, iii, 518
Post-Laramie, iii, 166
Post-Permian, sequences of,
ii, 660
Deformation of earth's crust, i,
526-589
causes of, i, 551-557, 574-589
relation to distribution of vol-
canoes, i, 601, 604, 627, 629
Deformation of ice, i, 312
Deformation, under Laplacian
hypothesis, ii, 125
Deformative movements of Ke-
weenawan, ii, 194
De Geer, G.3 cited, iii, 481, 482
Degradation, i, 2
by water, i, 58-177
rate of, i, 105
De Lapparent, A., cited, ii, 159,
215, 270, 338, 342, 514, 627,
628-631; i", 31, 33, 72, 74,
75, 77, 78, 127, 169, 216,
249, 252, 277, 279, 319
De Launay, L. C., cited, i, 474
Delaware beds, iii, 558
limestone, iii, 554
Delaware Water Gap, ii, 373
Delesse, A., cited, i, 221, 341
Delessite, i, 462
Dells of the Wisconsin, i, 152
Del Rio clay, iii, 117
Delta lakes, i, 204
Deltas, i, 181, 198-204
bottom-set beds, i, 202
development, i, 199
fore-set beds, i, 202
fossil, i 203
glacial, iii, 372
in tidal seas, i, 202
of the Ganges and Brahma-
putra, i, 202
of the Hoang-Ho, i, 202, 203
of the Mackenzie, i, 202
of the Mississippi, i, 197, 202
of the Nile, i, 202
of the Po, i, 202
of the Rhone, i, 203
of the Yukon, i, 202
rate of growth, i, 202
shape, i, 201
structure, i, 198, 199
top-set beds, i, 202
Dendrocrinus polydactylus, ii,
359
Densities within the earth, on
Laplace's law, i, 564
Dentalium attenuatum, iii, 294
Denudation and volcanic action,
1,627
Denver formation, iii, 156, 158
Deoxidation, i, 427
Deposition, by glaciers, i, 298-
305
by streams, i, 177-204
by shore currents, i, 355
by undertow, i, 355
by waves, i, 355-363
by wind, i, 25-37
Deposition of drift, at edge of
glaciers, i, 299
at end of glaciers, i, 299
beneath ice, i, 298
Deposition of mineral matter
from solution, i, 50, 225,
428
at surface, i, 50, 224
by ground-water, i, 224, 428
in lakes, i, 387
in sea, i, 375, 383
Deposition of sediment, i, 66
by rivers, i, 177-204
by wind, i, 25-38
in ocean, i, 355-363, 368-386
Deposits, deep-sea, i, 368, 378-
386
hot springs, i, 237, 241
lacustrine, i, 387
littoral, i, 369
made by animals, i, 658-663
Arthropoda, i, 662
Bryophytes, i, 656
Echinodermata, i, 661
ice, i, 298-305
Mollusca, i, 662
Molluscoidea, i, 662
plant kingdom, i, 652-658
Protozoa, i, 660
Pteridophytes, i, 657 .
rivers, i, 177-204 \
Spermatophytes, i, 657
Thallophytes, i, 653
Vermes, i, 662
Vertebrata, i, 663
wind, i, 25-38
shallow- water, i, 369-378
silicious, i, 237, 241, 425
terrestrial, iii, 298
tufa, i, 237, 241,473, 611,633
Depression and volcanic action,
i, 629
Depth of the ocean, i, 7
greatest, i, 8, 548
Derbyia crassa, ii, 616, 617
Deroceras subarmatum, iii, 81
Desert sandstone, iii, 171
Des Moines series, ii, 542. 561;
i", 558
De Soto beds, iii, 309
Devonian, abysmal life of, ii. 479
acanthodians, h, 489
actinopterygians, ii, 489
annelids, h, 467
592
INDEX.
Devonian arachnoids, ii, 495
arthrodirans, ii, 461, 469
arthropods, ii, 490
bacteria, ii, 493
brachiopods, ii, 464, 470
bryophytes, ii, 493
bryozoans, ii, 467, 477
calamarians, ii, 493
calamites, ii, 494
cephalopods, ii, 454, 459, 465,
473, 477
close of, ii, 439
corals, ii, 463, 470
cordaites, ii, 493
crinoids, ii, 456, 459: 464, 470
crossopterygians, ii 461
cycadofilices, ii, 493
echinoderms, ii, 459, 464, 470,
477
economic products of, ii, 440
equisetales, ii, 493
eurypterids, ii, 480, 490
fauna of the Great Basin area,
ii, 479
faunas, ii, 449
filices, ii, 493
fish, ii, 459, 460, 486
foreign, ii, 441
forests, ii, 493
ganoids, ii, 461
gas and oil of, ii, 440
gastropods, ii, 454, 459, 466,
473, 477
ginkgos, ii, 493
gymnosperms, ii, 492, 493
insects, ii, 494
land life of, ii, 491
land plants, ii, 491
lepidodendron, ii, 493
life, ii, 448
life of land waters, ii, 480
lycopodiales, ii, 493
Middle, ii, 424
geographic changes duringf
ii, 430
myriapods, ii, 495
ostracoderms, ii, 482, 483
outcrops of, ii, 438
pelagic life of, ii, 479
pelecypods, ii, 473, 477
period, ii, 418
phosphates of, ii, 440
protozoans, ii, 467
psaronius, ii, 493
pteridophytes, ii, 492, 493
pteropods, ii, 473
pteridosperms, ii, 493
scorpions, ii, 495
sigillaria, ii, 493
sphenophyllales, ii, 49^
spermatophytes, ii, 493
sharks, ii, 469, 489
sponges, ii, 467
subdivisions, of, ii, 418, 420
thallophytes, ii, 493
tree-ferns, ii, 493
trilobites, ii, 467, 477
Upper, ii, 430
of the West, ii, 435
Diabases, i, 418, 431, 469
Diadectes, ii, 650
Diadematoida, iii, 85
Diallage, i, 400, 462
Diamond Peak quartzite, iii, 576
Diapsida, ii, 647, 649; iii, 42
Diastrophism, i, 2, 329, 526
Archeozoic, ii, 144
effect on coast lines, i, 329
on planetesimal hypothesis, ii,
H7
Pleistocene, iii, 460, 465, 480
Diatom ooze, i, 380, 382, 425,
469
Dibelodon, iii, 285, 323
Dibranchiata, iii, 56
Diceratherium iii, 289
Dichocrinus inornatus, ii, 520
Dichograptus logani, ii, 362
octobrachiatus, ii, 362
Diconodon, iii, 255
Dicotyledons, introduction of, iii,
175
Dicranurus hamatus, ii, 455
Dictyonema beds, ii, 299
Dictyopteris rubella, ii, 593
Dicynodontia, ii, 650, 651
Didelphys, iii, 240, 253
Didymograptus, ii, 364
nitidus, ii, 362
Dielasma bovidens, ii, 616, 617
Differentiation of earth matter
by vulcanism, ii, 120
of rocks during growth of
earth, ii, 119
Diffusion, of carbonic acid gas
of ocean, ii, 666
cause of crustal movement, i,
555
in earth's interior, i, 555
Dikellocephalus, ii, 300
fauna, ii, 241, 299
pepinens's, ii, 299, 300
Dikes, i, 591
effect on topography, i, 143
limestone, iii, 263
sandstone, i, 514
Diller. J. S., cited, i, 29, 514; ii,
436, 555; iii, 67, 122, 160,
l6l, 164, 201, 202, 203, 212,
214, 264, 265, 266, 274, 277»
281 ; (and Stanton), iii, 122
Dimetrodon, ii, 648, 649
Dimorphodon, iii, 101
Dinichthys, ii, 461, 463
herzeri, ii, 463, 469
Dinictis, iii, 253
Dinoceras beds, iii, 208
mirabile, iii, 233
Dinocerata, iii, 232, 253
Dinorthis porca, ii, 367
Dinosauria, iii, 42
Cretaceous, iii, 176
Jurassic, iii, 97
Triassic, iii, 43
Dinotherium, iii, 285, 323
Diorites, i, 416, 452, 469
Dip, i, 501
quaquaversal, i 504
Dip-fault, i, 522
Diplacanthus, ii, 490
Diplacodon beds, iii, 209
Diplodus, ii, 614
Diplograptus pristis, ii, 362
Diplopodia texanum, lii, 135
Dipnoi, ii, 487
Dipterus, ii, 487
valenciennesi, ii, 488
Di Rossi, M. S., cited, i, 537
Discorbina turbo, iii, 241
Displacement of fault, i, 514
Disruption, tidal, ii, 22
Disruption of rock, by carbona-
tion, i, 43
by changes of temperature, L
44.49
by hydration, i, in
Disruptive approach, ii, 54
Distributive fault, i, 519
Divides, permanence of, i, 69
Docalcic rocks, i, 458
Dodge, R. E., cited, i, 204
Dofemane, i, 455
Dofemic rocks, i, 454
Doferrcus rocks, i, 459
Dohemic rocks, i, 457
Dolenic rocks, i, 456
Dolerites, i, 417, 452, 469
Dolichopithecus, iii, 325
Dolichosoma, ii, 6c8
Dolichosaurs, iii, 185
Cretaceous, iii, 180
Triass'c, iii, 43
Dolomites, i, 424, 469
Dolores formation, iii, 69
Domagnesic rocks, i, 459
Domalkalic rocks, i, 458
Domes of crust, strength of, i,
581, 582
Domilic rocks, i, 582
Domiric rocks, i, 458
Domirlic rocks, i, 458
Domitic rocks, i, 457
Don formation, iii, 491
Dopolic rocks, i, 456
Dopotassic rocks, i, 458
Dopyric rocks, i, 457
Doquaric rocks, i, 456
Dorycrinus, ii, 522
missouriensis, ii, 525
Dosalic rocks, i, 454
Dosiniopsis ler.ticularis, iii, 243
Dosodic rocks, i, 458
Dotilic rocks, i, 457
Double mountain formation, ii,
623
Drainage, changes in, effected by
glaciation, iii, 379
effect of change of level on, i,
161
mature, i, 86
of glaciers, i 273
old age, i, 89
youthful, i, 86
Drake, N. F., (and Lindgren,)
cited, iii, 210, 212, 299
Dreikanter, i, 40
Drepanochilus nebrascensis, iii»
189
Drift, i, 287, 469
bowlders of, iii, 340
INDEX.
593
Drift, composition of, 1,304; iii,
338
deposition of, i, 298-305
distribution of, iii, 343
stratified, extra-glacial, iii, 377
intermorainic, iii, 378
sub-morainic, iii, 377
super-morainic, iii, 377
topographic distribution of,
iii, 378
structure of, iii, 341
thickness of, iii, 346
topography of, iii, 344
wear of, in transit, i, 298
Drift and underlying rock, iii,
346
Drift-sheets, imbrication of, iii,
394
map of, iii, 390
relative ages of, iii, 414
Dromotherium, iii, 45
Drumlins, iii, 360, 361, 362
Drygalski, E. von, cited, i, 322
Dryolestes vorax, hi, 105
Dryopithecus, iii, 289
Dryptosaurus, iii, 176
Bumble, E. T., cited, ii, 320;
iii, 200, 262, 299, 302
Dump moraines, i, 301
Dundee limestones, iii, 353
Dune areas, topography of, i, 32
Dunes, i, 24-37
distribution of, i, 35
effect of vegetation on, i, 29
formation of, i, 26
migration of, i, 33
shapes of, i, 26
slopes of, i, 29
Dunkard series, ii, 542, 557,
558; iii, 554
Durocher, J., cited, ii, 84
Dust, volcanic, i, 22, 23
wind-blown, i, 22
Dust-wells, i, 269, 280
Dutton, C. E., cited,!, 132, 534,
574i 636; ii, 236; iii, 152,
214, 274, 275, 311, 312, 574
Dwyka conglomerate, ii, 602
Dyas formation, ii, 626
Dynamic geology, i, i
Eagle Ford formation, iii, 117,
142
Earlier Wisconsin glacial stage,
iii, 392
Early atmosphere, character of,
ii, 87
Early Cambrian, geography of,
ii, 222
Early climates, ii, 87
Early Cretaceous (see also
Comanchean), close of, iii,
130
Early glaciations, ii, 87
Early stages of earth's history,
nebular hypothesis, ii, 90
Earth, the, as a planet, i, 2
constitution, i, 5
crust, i, 13
deformation of, i, 526
Earth, the, dependence on sun,
1,4
distance from sun, i, 3
inclination of axis, i, 3
interior of, i, 14, 559
internal heat, i, 559-574
motions, i, 3
orbit, i, 3
sphere of activity for, ii, 62
structure, conceptions of, ii,
133
tremors of surface, i, 526
warpings of crust, i, 526-89
Earth-moon ring, ii, 5
Earthquake vibrations, i, 526
amplitude of, i, 529
sequences of, i, 533
Earthquakes, i, 527-537
causes of, i, 527
Charleston, i, 534
destruction of life by, i, 536
destructive effects of, i, 530
distribution of, i, 533
epicentra of, i, 531
foci of, i, 527
gaseous emanations during, i,
533
geologic effects of, i, 534-537
Lisbon, i, 535
Earth's crust, composition of, i,
14, 396
warpings of, i, 538-551
Earth's history, atmosphereless
stage, ii, 92
atmospheric stage, ii, 95
hypothetical early stages of,
under Laplacian hypoth-
esis, ii, 82
nuclear stage, ii, 92
synoptical view of, ii, 119
Earth's origin, ii, i
hypotheses of, ii, 3
Eastern Interior coal-field, ii,
548
Eastern provinces of Canada,
Proterozoic of, ii, 204
Eastman, C. R., cited, i, 658; ii,
430
Easton schist, iii, 267
Eatonia, ii, 459; iii, 295
medialis, ii, 455
Ecca shales, ii, 636
Eccentricities of planetary or-
bits, ii, 79
Eccyliomphalus triangulus, ii,
353
Echinocaris punctata ii, 471
Echinodermata, geologic con-
tributions of, i, 661
Echinoderms, Cambian, ii,
286
Devonian, ii, 459, 464, 470,
477
Jurassic, iii, 91, 92
Mississippian, ii, 519, 522,
530
Ordovician, ii, 357, 359
Pennsylvanian, ii, 617
Silurian, ii, 400
Triassic, iii, 57
Echinoidea, iii, 134
Comanchean, ii, 135
geologic contributions of, i,
661
Jurassic, iii, 85
Miocene, iii, 294
Triassic, iii, 57
Economic geology, i, I
Ecphora, iii, 294
quadricostata, iii, 294
Ectenocrinus grandis, ii, 359
Edaphic development of Ordovi-
cian life, ii, 343
Eden shale, iii, 555
Edentata, iii, 229
Eocene, iii, 238
Efflorescence, i, 42
Egypt, Pliocene of, iii, 320
Ehrenbergia, iii, 294
Elaeolite, i, 462
Elbert formation, iii, 573
Eldridge, G. H., cited, ii, 154,
506,563; iii, 116, 201, 263;
(and Cross and Emmons),
iii, 570
Electricity, atmospheric, i, 43
chemical effects of, i, 43
geological effects of, i, 43
52
Elephants, Pleistocene, iii, 496
Pliocene, iii, 323
Elephas primigenius, iii, 324
Eleutherocrinus, ii, 470
cassedayi, ii, 471
Elevation hypothesis of glacial
climate, iii, 424
Elevation, post-Pliocene, and
climate, iii, 316
Elk River series, ii, 558
EHensburg formation, iii, 211,
266, 267
Ellipsoidina, iii, 294
Ellipticity of orbit of planetesi-
mals, ii, 65
Ellis formation, ii, 153; iii, 70,
157, 166,568
Ells, R. W., cited, i, 443; ii, 141;
iii, 370
Elotheres, Miocene, iii, 284
Oligocene, iii, 255
Elotherium, iii, 253
crassum, iii, 234
Ely greenstone, ii, 150
Embolophorus, ii, 649
Emerson, B. K., cited, ii, no,
213, 549J i", ii, 14, 546
Emmons, E., cited, ii, 145, 310,
370
Emmons, S. F., cited, i, 474; ii,
26, 154, 267, 268, 505, 507,
510, 552; iii, 149, 155, 164;
(and Cross and Eldridge),
i", 570
Emmons, W. H., cited, i, 474,
573,585
Empedias, ii, 650
Empire beds, iii, 263
Encrinital limestone, ii, 523
Endothyra baileyi, ii, 531, 532
Energy of ancestral system, ii, 51
594
INDEX.
Englacial drift, i, 282
England, Cambrian of, ii, 271
Cretaceous, Lower, iii, 126
Devonian of, iii, 443
Eocene of, iii, 215
Jurassic of, iii, 70
Middle Jurassic, coal of, iii, 73
iron ore of, iii, 73
Mississippian of, ii, 513
Oligocene of, iii, 249
Ordovician of, ii, 340
Pennsylvanian of, ii, 585
Permian of, ii, 626, 628
Pliocene of, iii, 318
Triassic of, iii, 33
(See also Great Britain)
Englewood limestone, iii, 68,
5<>7
English, T., cited, iii, 251,279,
3i8
Engonoceras, iii, 134
Enlargement of crystals, by sec-
ondary growth, i, 435
Ensis, iii, 295
directus, iii, 292
Enstatite, i, 400, 462
Enteletes hemiplicata, ii, 616,
617
Eocene amphibians, iii, 240
artiodactyls, iii, 236
birds, iii, 240
camels, iii, 236
creodonts, iii, 236
edentates, iii, 238
foraminifera, iii, 241
gastropods, iii, 243
grasses, iii, 231
horses, iii, 235
insectivores, iii, 239
insects, iii, 240
land animals, iii, 228
life, general conditions, iii,
221
marine mammals, iii, 239
molluscs, iii, 243
oreodons, iii, 236
pelecypods, iii, 243
perissodactyls, iii, 235
placentals, iii, 228
primates, iii, 239
reptiles, iii, 240
rodents, iii, 238
Eocene period, iii, 191
Bridger stage, iii, 208
close of, iii. 214, 221
conditions during, iii, 213
duration oft iii, 212
formations and physical his-
tory of, iii, 196
Ft. Union stage, iii, 205
geography of, iii, 220
igneous activity of , iii, 212
Uinta stage, iii, 209
Wasatch stage, iii, 208
Eocene system, Africa, iii, 219
Alabama, section of, iii, 199
Asia, iii, 219
Atlantic coast, iii, 198
Australia, iii, 219
brackish-water beds, iii, 202
Eocene system, British Columbia,
iii, 203
California, iii, 201
Central America, iii, 220
coal of, iii, 202
Europe, iii, 215
foreign, iii, 215
Gulf border, iii, 199
map of, iii, 197
oil of, iii, 201
Pacific coast, iii, 200
South America, iii, 219
terrestrial formations, iii, 204
Texas, iii, 200
West Indies, iii, 220
Eocene vegetation, iii, 226
Eocystites longidactylus, ii, 286
primaevus, ii, 286, 299
Eolian deposits, Pleistocene, iii,
446
in west, iii, 454, 474
Eolian rocks, i, 469
Eoscorpius carbonarius, ii, 611
Eotrochus concavus, ii, 532
Epeirogenic movements, i, 537
Epicontinental seas, i, ii, 326
Epidote, i, 431, 462
Epihippus, iii, 235
Eporeodon sociates, iii, 234
Equisetae, geologic contribution
of, i, 657
Triassic, iii, 40
Equisetales, ii, 596
Carboniferous, ii, 597
Devonian, ii, 493
Mississippian, ii, 537
Triassic, iii, 38
Equisetites, Permian, ii, 642
Equus, iii, 323
beds, iii, 564
Eras, i, 17-19
Eretmocrinus remibrachiatus, ii,
525
Brian series, ii, 426
Erosion, affected by rotation, i,
194
analysis of, i, no
base-level of , i, 60
by glaciers, i, 281-286
by rain, i, 57
by rivers, i, 56-177
by undertow, i, 342, 346
by waves, i, 342-349
by wind, i, 38
conditions affecting rate of,
by glaciers, i, 283
conditions affecting rate of,
by running water, i, 123
cycle of, i, 80, 82, 164
in arid regions, i, 131
influenced by climate, i, 127,
128, 129
composition of rock, i, 124
declivity, i, 123
structure, i, 124, 126
vegetation, i, 129, 644
sheet, i, 59
subaerial, i, 58
Erosion and cleavage planes, i,
125
Erosion and joints, i, 125
Erosion by streams (see Erosion
by running water)
Eruptions, i, 591
fissure, i, 593
igneous, Cretaceous, iii, 167
volcanic, i, 594
Escabrosa limestone, iii, 575
Escombe, cited, ii, 605
Escondido formation, iii, 201
Eskers, i, 306; iii, 314
Esmeralda formation, iii, 266
Esopus grit, ii, 422
Etheridge, R., cited, ii, 272
Etna, i, 605, 610
discharge of stream, i, 636
Eucalyptocrinus crassus, ii, 403
Eucalyptus, iii, 132, 173
Euconulus fulvus, iii, 410
Eugnathus athostomus, iii, 87
Eumetria, ii, 531
marcyi, ii, 532
Eumys, iii, 253
Eunicites, varians, ii, 363
gracilis, ii, 363
Euomphalus, Onondagan, ii, 466
Eupachycrinus magister, ii, 616,
617
Euphoberia armigera, ii, 6n
Eureka District, Nevada, section
of strata, iii, 576
Eureka quartzite, iii, 576
Eureka rhyolite, iii, 572
Eureka shale, ii, 562 ; iii, 60
Europe, Archean of, ii, 158
Cambrian of, ii, 270
Carboniferous of, ii, 584
chalk of, iii, 169
close of Jurassic in, iii, 79
Cretaceous of, iii, 167
crustal movements of Mio-
cene in, iii, 280
Devonian of, ii, 441
Eocene of, iii, 215
Glacial period of, iii, 42
iron-ore in Cretaceous of, iii,
170
iron-ore in Lower Cretaceous
of, iii, 128
Jurassic of, iii, 70
Lias of, iii, 72
Lower Cretaceous of, iii, 126,
128
Lower Jura of, iii, 72
Middle Jura of, iii, 73
Mississippian of, ii, 51 1
Miocene of, iii, 276
Oligocene of, iii, 248
Oligocene coal of, iii, 250
Oligocene igneous rocks of,
iii, 251
Ordovician of, ii, 338
Pennsylvanian of, ii, 585
Permian of, ii, 625
Pleistocene of, iii, 421
Pleistocene life of, iii, 498
Pliocene of, iii, 318
Proterozoic of, ii, 215
Silurian of, ii, 395
Triassic of, iii, 30
INDEX.
595
Eurychilina reticulata, ii, 351
Eurylepis, ii, 614
Eurypterids, Devonian, ii, 480,
490
Eurypterus fischeri, ii, 413
Eusmilus, iii, 237, 253
Eusthenerpteron, ii, 488
Eutaw formation, iii, 141
Evans, Sir J., cited, iii, 503
Evaporation, i, 50
Everett, cited, i, 578
Evolution, restrictive and ex-
pansional, i, 672; ii, 399
Exfoliation, i, 44
Exogyra, iii, 82
costata, iii, 189
virgula, iii, 83
Expansion and contraction, due
to temperature, i, 44
due to wetting and drying, i, 52
Expansional evolution, i, 672
Explosion, origin of nebulae by,
ii, 21
Explosive elasticity of sun, ii, 55
Extinct lakes, i, 388
Extrusive processes, i, 590-637
Fagus, iii, 173
Fairbanks, H. W., cited, iii, 64,
67, 68, 69, 122, 123, 124,
125, 160, 262, 263, 299, 310,
315,477,577
Fairchild, H. L., cited, iii, 380,
395, 482
Falb, R., cited, i, 537
False bedding, i, 487
Farrington, O. C., cited, ii, 23, 25,
29, 30, 120
Fault, overthrust, of British
Columbia, iii, 165
Fault scarp, i, 514
Faulting at close of Laramie, iii,
164
at close of Pliocene, iii, 313
Newark series, iii, 12
normal conditions for, ii, 235
post-Cretaceous, iii, 164
and vulcanism, i, 627
Faults, conditions of, i, 521
dip, i, 522
displacement, i, 514
distributive, i, 519
effect on outcrops, i, 522
hade, i, 514
heave of, i, 514
normal, i, 517; ii, 235
oblique, i, 525
relations to folds, i, 515
reversed, i, 517, 521
stratigraphic throw, i, 518
significance of, i, 521
strike, i, 522
thrust, i, 517, 518
Faunas, abysmal, i, 670
Australian, i. 668
cold and warm, superposition
of, in Pleistocene, iii, 487
cosmopolitan, i, 668
deep-sea, i, 670
pelagic, i, 670
Faunas, photobathic, i, 670
Faunas and floras, basis of, i,
663
effect of geographic conditions
on evolution of, i, 668
Favosites, ii, 457
gothlandica, ii, 409
occidens, ii, 406
Silurian, ii, 407
Fayette breccia, iii, 558
formation, iii, 244
Feldspar, i, 462
Feldspar-leucophyres, i, 453
Feldspar-melaphyres, i, 453
Feldspathic minerals, i, 400
Feldspathoids, i, 400
Felis, iii, 289
Felsites, i, 452, 469
Fenestella, ii, 405
emaciata, ii, 471
parvulipora, ii, 406
Fenneman, N. M., cited, 1,339;
iii, 362
Ferguson, A. M., cited, i, 203
Ferns, Devonian, ii, 493
geologic contribution of, i,
657
Mississippian, ii, 537
Fernvale formation, iii, 552
Ficus, iii, 133, 173
inaequalis, iii, 174
Filicales, Carboniferous, ii, 593
Pennsylvanian, ii, 592
Fiords, i, 290; iii, 530
Fisher, O., cited, i, 561, 565, 574,
58i
Fishes, Carboniferous, ii, 614
Cretaceous, iii, 185
Devonian, ii, 486
Helderbergian, ii, 457
Jurassic, iii, 85
Mississippian, ii, 535
Onondagan, ii, 460
Ordovician, ii, 347
Oriskany, ii, 459
Permian, ii, 652
Silurian, ii, 409, 417
Fissure eruptions, i, 593
Fissuridea alticosta, iii, 294
griscomi, iii, 294
Flaming Forge formation, iii,
3i3
Flathead quartzite, iii, 70, 166,
569
Flattop schist, ii, 152
Flaxseed iron ore, ii, 377
Flemingites, iii, 52
Fletcher, G., (and Deeley, R. M.,)
cited, i, 322
Fletcher, H., cited, ii, 504
Flints, i, 426, 469
Floods, i, 109
of the Mississippi, i, 188
Flood-plain meanders, i, 190
Flood-plains, i, 184-198
development of, i, 165
materials of, i, 196
Mississippi, i, 194
relation to terraces, i, 203
topography, {,196
Floras, cold and warm, super-
position in Pleistocene, iii,
487
Floras and faunas, basis of, i, 663
effect of geographic conditions
on, i, 668
Florida, phosphates of, iii, 261
Florissant beds, iii, 247
fossils, iii, 252
Flow structure of lavas, i, 410
Flowering plants, geologic con-
tributions of, i, 657
Flowing wells, i, 234, 242
Floyd shale, iii, 551
Fluor ite, i, 462
Fluviatile deposits, Pleistocene,
iii, 446
Fluvio-glacial deposits, iii, 368
Fluvio-glacial work, i, 305-307
Flysch conglomerate, iii, 172,
218, 250
Foerste, A. F., cited, ii, 280, 335,
544, 549
Folded ranges, distribution of, i,
543
Folding, location of, ii, 127
periodicity of, ii, 128
Folding and vulcanism, i, 628
Folds, anticlinal, i, 504, 505
effect on valleys, i, 154
isoclinal, i, 504
synclinal, i, 504
Folds and faults, i, 515
Foliation of ice, i, 272
of rocks, i, 443
zone, ii, 130
Fontaine, Wm. M., cited, iii, 40,
132
Foraminifers, Cretaceous, iii, 186
Eocene, iii, 241
geologic contribution of, i, 660
Jurassic, iii, 85
Miocene, iii, 294
Triassic, iii, 57
Forbes, J. D., cited, i, 256, 322
Forbesicrinus wortheni, ii, 525
Ford, S. W., cited, ii, 280
Fordilla troyensis, ii, 284
Foreign Ordovician, ii, 338
Fore], F. A., cited, i, 323, 386
Fore-set beds, i, 202
Forests, Devonian, ii, 493
Formation, i, 487
Forster, W. G., cited, i, 536
Fort Payne chert, iii, 551
Fort Pierre beds (see Pierre)
Fort Union stage of Eocene, iii.
205
Foshay, P. M., cited, iii, 382
Fossil deitas. i, 203
Fossil iron ore, ii, 377
Fossils, i, 16, 646
a means of correlation, i, 647
Pleistocene, mixing of, iii, 488
Fossils and stratigraphy, i, 647
Fouque", F., cited, i, 635, 636
Fox Hills fauna, iii, 190
formation, iii, 151, 566, 570
Fraas, E., cited, iii 90, 246
Fracture, zone of, i 219
596
INDEX.
France, Archean of, ii, 159
Cretaceous, Upper, of, ni, 169
Devonian of, ii, 442
Eocene of. iii, 215, 217
Jurassic of, iii, 71, 76
Miocene of, iii, 277
Mississippian of, ii, 515
Oligocene of, iii, 249, 250
Pennsylvanian of, ii, 585
Permian of, ii, 626 627
Pliocene of. iii, 318, 319
Proterozoic of, ii, 215
Franciscan series, iii, 577
Frank, A. B., cited, i, 642
Freeh, F., cited, ii, 271
Fredericksburg series, iii, 116
Free-molecular nebulae, ii, 41
Freestone, i, 469
French Broad river, i, 168
Fresh-water fauna , Coman-
chean, iii, 134
Fresh- water life, Permian, ii, 652
Fresh- water mo Husks, Devonian,
ii, 490
Fresh-water plants, Devonian, ii,
490
Frontal aprons, iii, 372
Fulgur spiniger, iii, 294
Fulgurites, i, 52, 469
Fuller, M. L., cited, ii, 433, 509.
557; iii, 412; (and Clapp),
iii, 212
Fundamental gneiss, ii, 142
Fungi, geologic contribution of,
i, 653
Fusion, selective, ii, 102
Fuson formation, iii, 566
Fusulina cylindrica, ii, 618
secalius, a, 616
limestone, ii, 587, 618
Fusus, iii, 294
interstriatus, iii, 243
texanus, iii, 135
Gabb, Wm. M., cited, iii, 309;
(and Whitney), iii, 122
Gabbroids, i, 453
Gabbros, i, 416, 452, 469
Galena-Trenton limestone, ii,
313, 320; iii, 557, 559
Galenite, i, 441
Galeocerdo, iii, 294
Gallatin limestone, ii, 153; iii,
70, 166, 569
Gangamopteris cyclopteroides, ii,
645
Ganges River, delta of, i, 203
Gangue, i, 469
Gannister, i, 469
Ganodonta, iii, 229, 238
Ganoids, Devonian, ii, 461
Garnet, i, 462
Garnetite, i, 469
Garrey, G. A., cited, iii, 340;
(and Blackwelder), iii, 334
Gas and oil of the Devonian, ii,
440
Gaseous center of earth, ii, 9
Gaseous emanations during
earthquakes, i, 533
Gaseous emanations from vol-
canoes, i, 617
Gaseous spheroids, formation of,
ii,5
Gases in igneous rocks, i, '619;
ii, 95
in meteorites, ii, 95
Gases volcanic, i, 617-623
amount of, i, 620
kinds of, i, 618, 619
proportions of, i, 620, 622
sources of, i, 621
Gastropods, Cambrian, ii, 297
Carboniferous, ii, 615, 616
Chemung, ii, 478
Comanchean, in, 134, 135, 136
Cretaceous, iii, 187, 190
Devonian, ii, 473, 477
Early Jurassic, iii, 91
Eocene, iii, 243
Genevieve. ii, 532, 533
geologic contributions of, i,
662
Helderbergian, ii, 454
Jurassic, iii, 83
Kinderhook, ii, 520, 521
Middle Jurassic, iii, 91
Miocene, iii, 293, 294
Mississippian, ii, 523
Onondagan, ii, 466
Ordovician, ii, 353, 354
Permian, ii, 653
Silurian, ii, 403, 406
Triassic, iii, 56
Upper Cambrian, ii, 299. 300
Upper Jurassic, iii, 91
Gaudry, A., cited, iii, 324
Gault series, iii, 128
Gavials, Cretaceous, iii, 179
Gay Head, Pliocene of, iii, 308
Geanticline, i, 505
Geest, i, 469
Geikie, A., cited, 1,203, 224, 344,
534.536,636; ii. 158. 215,
269, 339, 340, 445. 447, 448,
514, 515, 517, 566, 585, 588,
589,626,632; iii, 72, 73, 76*
78S 170, 227, 277, 278, 281
Geikie, J., cited, iii, 35, 79, 217,
218, 328, 384, 421, 422, 423,
499, 5i6
Genesee formation, ii, 432
Genevieve blastoids, ii, 532
brachiopods, ii, 531, 532
bryozoa, ii, 531, 532
cephalopods, ii, 532, 533
corals, ii, 530
crinoids, ii, 530, 532
fauna, ii, 529
gastropods, ii, 532, 533
mollusks, ii, 533
pelecypods, ii, 532, 533
productus, ii, 531
protozoa, ii, 531, 532
Geodes, i, 436, 497
Geognosy, i, 1,5, 393-485
Geographic changes during Mid-
dle Devonian, ii, 430
features of the Permian glacial
stage, ii, 675
Geologic effects of earthquakes.
i, 534
Geologic functions of life, i, 638
Geologic processes, man's in-
fluence on, i, 649; iii, 541
Geologic time divisions, table of,
i, 19; ii, 160
Geology, general subdivisions of,
i, i
prognostic, iii, 542
George, R. D., cited, i, 545
Georgia, section of strata in; iii,
551
Georgian series, ii, 219, 241
Geosaurus suevicus, iii, 90
Geosyncline. i, 505
Geotectonic geology, i, i, 486-
525
Gerber, E., cited, i, 195
Germg beds, iii, 269, 564
Gerland, cited, i, 538
Germany, Archean of, ii, 159
Cretaceous, Lower, iron ore of,
iii, 128
Devonian of, ii, 442
Jurassic of, iii, 72
Miocene of, iii, 276
Mississippian of, ii, 513
Oligocene of, iii, 248
Pennsylvanian of, ii, 585
Permian of. ii, 626-630
Pleistocene of, iii, 424
Proterozoic of, ii, 215
Triassic of, iii, 31
Triassic coal beds of, iii, 40
Gervillia, iii, 91
Geschiebewall, i, 300; iii, 367
Geyser ite, i, 463, 469
Geysers, i, 236
deposits of, i, 237
of Yellowstone Park, i, 239
period of eruption, i, 240
positions of, i, 241
Gibbon, iii, 326
Gibbula, iii, 295
Gilbert, G. K., cited, i, n, no,
140,194,198,203,339,355,
388, 489, 596; ii, 382; iii,
26, 59, 194, 242, 415, 418,
419, 455, 456, 458, 460, 461,
479, 482, 483, 516; (and
Putnam), ii, 236
Ginkgkodium, iii, 95
Ginkgos, Carboniferous, ii, 601
Cretaceous, iii, 173
Devonian, ii, 493
Triassic, iii, 40
Giraffes, Pliocene, iii, 323
Girty, G. H., cited, ii, 510, 553i
563, 623
Glacial beds, Cambrian, ii, 272
Carboniferous of Europe (?),
ii, 587
Permian; ii, 632
Glacial climate, astronomic hy-
potheses of, iii, 426, 431
atmospheric hypotheses of, iii,
432
Croll's hypothesis of, iii, 426
elevation hypothesis of, iii, 424
INDEX.
597
Glacial climate, hypsometric
hypotheses of, Hi. 424
wandering pole hypothesis of,
iii, 43i
Glacial debris, how carried, i, 290
nature of, i, 286
shifting position in transit, i,
292, 293, 294, 296, 297
Glacial deposits, nature of, i, 304
of western mountains, iii, 467
Glacial erosion, conditions in-
fluencing, i, 283
topographic effects of, i, 287
Glacial man, sources of evidence
of. iii, 512
Glacial motion, i, 313-321
auxiliary elements of , i, 317
fundamental element of, i, 313
Glacial Period (Pleistocene), iii,
327
Asia, iii, 424
cause of, iii, 424
duration of, iii, 413
Europe, iii, 421
glacio-lacustrme substage of,
"i, 394
mountain glaciation of, iii, 333
stages of, iii, 383
Glacial planation, iii. 346
plucking, i, 282
striation, iii, 346
Glaciated areas, rate of migra-
tion of plants in, iii, 533
reforestation of, iii, 530
re-peopling of, iii, 530
Glaciated rock surfaces, i. 304
Glaciation (Pleistocene), centers
of, in North America, iii, 330
changes in drainage effected
by, iii, 379
criteria of, iii, 337
effects of, on life, iii, 483
general distribution of, iii, 327
Greenland, iii, 336
island, iii, 336
localization, iii, 433
mountain, iii, 333
Newfoundland, iii, 336
Nova Scotia, iii, 336
periodicity of, iii, 433
special causes of, iii, 436
Glacier ice, beginning of move-
ment, i, 248
definition of, i, 250
granular texture of, i, 247
shearing of, i, 317
Glacier movement, i, 259, 313-
323
at low temperature, i, 279
effect of water on, i, 318
rates, i, 260, 261
views of, i, 321
Glaciers, alpine, i, 254
cliff, i, 256
compared with rivers, i, 262
conditions influencing move-
ment, i, 261
constitution, i, 308
continental, i, 251
crevasses, i, 264
Glaciers, deformation, i, 312
drainage of, i, 273, 280
evaporation, i, 279
foliation, i, 247, 272
general phenomena, i, 256
getting load, i, 282
growth of, i, 308
growth of granules, i, 310, 31 1
high-latitude, i, 254
limits of, i, 258
motion in terminal part, i, 316
movements of, i, 259, 279, 313-
323
piedmont, i, 254
polar, i, 254
rate of movement of, i, 260,
261
reconstructed, i, 256
stratification of, i, 247
structure of, i, 308
surface features of, i, 266
talus, iii, 474
temperature of, i, 273-279
thickening of layers at end, i,
297
topography of< i, 266
types of, i, 251
upturning of ice at ends and
edges, i, 296-298
valley, i, 254
waste of, i, 273
work of, i, 244, 281
Glacio-fluvial work, i, 305-308
Gladeville sandstone, ii, 559
Glance conglomerate, iii, 575
Glass, volcanic, i, 451
Glassy rocks, i, 406
Glauconia, iii, 134
Glauconite, i, 384, 386, 463 ; iii,
128, 198
Cretaceous, iii, 139
origin of, iii, 139
Gleeson, G. M., cited, iii, 497
Glenn, L. C., cited, iii, 17
Globigerina, iii, 189
bulloides, iii, 241
ooze, i, 380, 382, 660
Globulites, i, 407, 469
Glossopteris, ii, 603; iii, 40
angustifolia, ii, 645
commusis, ii, 645
flora, ii» 602, 645, 646
Glycimens, iii, 295
idoneus, iii, 243
Glyphaea, iii, 91
Glyptocrinus decadactylus, ii, 359
Glyptocystis multiporus, ii, 359
Glyptodon, iii, 322, 498
Gnathosauria, iii, 42
Gneiss, i, 415, 446. 448, 469
Golden Gate series, iii, 64, 69
Goldthwait, J. W., (and Hunt-
ingdon,) cited, iii, 313
Gomopteris, ii, 644
Gomphoceras.Onondagan, 11,466
Gondwana system, ii, 634
Goniatites, ii, 465
kentuckiensis, ii, 532
Triassic, iii, 56
vanuxemi, ii, 471, 473
Goniobasis (?) ortmanni, iii, 134
Goniomya, iii, 91
Goniophyllum pyramidale, ii,
406, 409
Silurian, ii, 407
Gooch, F. A., (and Whitfield, J.
E.v) cited, i, 236
Goodnight beds, iii, 269, 300
Goshen schist, iii, 546
Gould, C. N., cited, ii, 543, 621;
iii, 24. 118
Grad, C., cited, i, 322
Gradation, i 2
by running water, i, 56-212
effect on coast-lines, i 334
in ocean, ., 334
Gradation and submergence, ii,
231
Grade, i, 61
Graded plain, i, 82, 169
Graded valley, i, 83
Grainger shale, ii, 559; iii, 549
Grammatodon inornatus, iii, 93
Grammoceras, iii, 91
Grammysia hannibalensis, ii, 520
Granby tuff, iii, 546
Grand Canyon, section of strata
in, iii, 574
Grand Canyon series, ii, 153
Grand 'Eury, C., cited, ii, 598
Grand Gulf formation, iii, 244,
309
Grand Rapids series, ii, 504; iii,
553
Graneros shale, iii, 155, 206, 565,
566
Granite, crushing strength of, it.
127
Granitell, i, 470
Granites, i, 413, 452, 469
Granitite, i, 470
Granitoids, i, 420, 453
Granulite, i, 470
Graphite, i, 426, 463
Graptolites, ii, 457
Cambrian, ii, 286
Helderbergian, ii, 457
Ordovician, ii, 344, 362
Silurian, ii, 408
Grasses, Cretaceous, iii, 173
Eocene, iii, 231
Miocene, iii, 283
Gravels, auriferous, of California,
iii, 265, 274, 299
Buchanan, iii, 383
Gravitational energy, i, 552
force, i, 552, 553
Gravity, a cause of crustal move-
ments, i, 552
effect on erosion, i, 113
Gray, T., (and Milne, J.,) cited, i,
578
Great Basin area, Devonian
fauna of, ii, 479
Mississippian fauna of, ii, 527
'Great Britain, Archean of, ii, 158
Cambrian of, ii, 270, 271
coal of, ii, 586
Devonian of, ii, 443
Eocene of, iii, 215
598
INDEX.
Great Britain, Jurassic of, iii,
72, 76
Mississippian of, ii, 513
Oligocene of, iii, 249
Ordovician of, ii, 339, 340
Pennsylvanian of, ii, 586
Permian of, ii, 626-628
Pleistocene of, iii, 421
Pliocene of, iii, 318
Proterozoic of, ii, 213
Silurian of, ii, 395
Great Salt lake, iii, 455
salts in, iii, 458
Green River group, iii, 208
Greenalite, ii, 189
Greenbrier limestone, ii, 500,
502, 558, 559; i", 548
Greenhorn limestone, iii, 155,
206, 566
Greenland, climate of, in Mio-
cene, iii, 281
Comanchean of, iii, 124
glaciation of (Pleistocene), iii,
336
glaciers of, i. 246
ice, rate of movement of, iii,
430
Ordovician of, ii, 342
snow-fields of, i, 245
snow-line in, i, 246
Green mud, i, 380
Greensand, i, 470
Cretaceous, iii, 186
marl, i, 386; iii, 139, 198
Greenstone, is 419, 470
Gregory, H. E., (and Williams,)
cited, ii, 434
Greisen, i, 415, 470
Greyson shales, iii, 569
Greywacke, i, 470
Griswold, L. S., cited, ii, 320
Ground ice, i, 119
Ground moraine, i, 301 ; iii, 360
Ground- water, i, 213-243
affects internal heat, i, 570
amount of, i, 221
descent of, i, 213
fate of, i, 221
level, i, 71, 215
lower limit of, i, 216
movement of, i, 220
results of, i, 226
solution by, i, 222, 223
surface, i, 71, 215
work of, i, 222
Ground- water and vulcanism, i,
635
Gryphsea, iii, 82
arcuta, iii, 83
calceola, iii, 92
vesicularis, iii, 189
Guano, i, 646
Guelph dolomite, ii, 370, 377, 385
fauna, ii, 389
Guernsey formation, ii, 208; iii,
565
Gulf coast, Comanchean of, iii,
1 08
Cretaceous of, iii, 140, 142
Eocene of, iii, 199
Gulf coast, Miocene of, iii, 261
Pliocene of, iii, 309
Gulf stream, i, 366
Gullies, growth of, i, 63
Gulliver, F. P., cited, iii, 370,
373
Gumbel. C. W-, cited, ii, 159, 251
Gunflint formation, ii, 190
Gunnison formation, ii, 154; iii,
570
Gurley, R. R., cited, ii, 345
Gurnsey formation, ii, 209
Guyandot sandstone, ii, 559
Gymnoptychus, iii, 253
Gymnosperms, Cretaceous, iii,
173
Devonian, ii, 492, 493
geologic contribution of, i, 657
Mississippian, ii, 537
Pennsylvanian, ii, 600
Triassic, iii, 38, 41
Gypidula comis, ii, 475, 476
galeata, ii, 455
Gypsum, deposition of, i, 376,
377
Grand Gulf, iii, 244
Mississippian, ii, 517, 518
Pennsylvania, ii, 627
Permian, ii, 623, 628
Pliocene, iii, 318
Salina series, ii, 388
Siberia, ii, 342
Triassic, iii, 25, 29, 34, 35
Upper Permian, ii, 630
Gyroceras, ii, 473
duplicicostatum, ii, 352
Onondagan, ii, 466
Gyronites, iii, 52
Haast, J., cited, ii, 159
Hade of faults, i, 514
Haehl.H. L., (and Arnold,) cited,
iii, 263
Hague, A., cited, iii, 210, 212,
576
Hall, C. W., cited, ii, 194, 205
Hall, J., cited, i, 511; ii, 280,
310; iii, 361; (and Whit-
ney), ii, 314
Halleflinta, i, 470
Halonia, Mississippian, ii, 537
Halophytes, geologic contribu-
tions of, i, 667
Halysites catenulatus, ii, 367,
406, 409
Silurian, ii, 407
Hamburg limestone, iii, 576
Hamburg shale, iii, 576
Hamilton arthrodirans, ii, 469
brachiopods, ii, 470
bryozoans, ii, 477
cephalopoda, ii, 477
corals, it, 470
crinoids, ii, 470
echinoderms, ii, 477
fauna, ii, 452, 471
northwestern, ii, 474
southern, ii, 468
gastropods, ii, 473, 477
Milwaukee, ii, 477
Hamilton pelecypods, ii, 473, 477
pteropods, ii, 473
series, ii, 426; iii, 556
sharks, ii, 469
trilobites, ii, 473, 477
Hamites, iii, 134
Hampshire formation, iii, 548
Hampton shale, ii, 152
Hanbury slate, ii, 187
Hanging valley, i, 164, 290
Hannibal shales, ii, 561
Haplacodon, iii, 255
Harleck group, ii, 271
Harmer, F. W., cited, iii, 445
Harpes pr.rnus, ii, 349
Harris, G. F.. cited, ii, 408
Harris, G. D., cited, iii, 200;
(and Dall), iii, 258, 261 , 262,
309; (and Veach), 411
Harrodsburg limestone, iii, 556
Hartnagel, C. A., cited, ii, 370,
389, 390
Hartshorne sandstone, iii, 562
Harttia matthewi, ii, 298, 299
Hartville formation, iii, 565
Harvey conglomerate, ii, 559
Haseltine, R. M., cited, n, 546
Hastings district, ii, 204
Hastula, iii, 294
Hatcher, J. B., cited, iii, 119,
194, 219, 252, 281; (and
Stanton), 152
Hauynite, i, 463
Hawksbury sandstone, iii. 38
Hawley schist, iii, 546
Haworth, E., cited, iii, 269,
300
Hay, O. P., cited, iii, 532
Hayden, F. V., cited, iii, 208
Hayes, C. W., cited, i, 173; (a. id
Campbell, M. R.), 171; ii,
254, 268, 315, 323, 33 1,
337, 540, 544, 546; (and
Ulrich), 316, 335, 420, 427,
434, 440; iii, 262, 305, 551;
(and Kennedy), 200; (and
Ulrich), 552
Head erosion, i, 64
Heat, causes crustal movement,
i, 557
causes of, in ice, i, 278, 279,
3ii
distribution of, original, i, 559
within earth, i, 559
from compression, ii, 101
condensation, ii, 101
infall, ii. 101
molecularre arrangement, ii,
101
internal, of earth, i, 550-570?
ii, 101
metamorphism by, i 446,
448
source of, for vulcanism, ii,
100
Heave of faults, i, 514
Hector, Sir J., cited, ii, 159
Hedera, iii, 173
Heer, O., cited, ii, 602; iii, 132,
195, 281, 283
INDEX.
599
Heilprin, A., cited, 1,636; '111,242
Heim, A., cited, i, 256, 322, 549,
576
Helderbergian brachiopods, ii,
454
cephalopods, ii, 454
corals, ii, 456, 457
crinoids, ii, 456
cystids, ii, 456
fauna, ii, 450, 453, 455
fishes, ii, 457
formation, ii, 370, 391, 420
gastropods, ii, 454
graptolites, ii, 457
pelecypods, ii, 454
trilobites, ii, 456
Helicoceras stevensoni, iii, 189
Helicotoma planulata, ii, 353
Heliolites interstinctus, ii, 409
Helladotherium, iii, 323
Helvetian epoch, iii, 421
Hematite, i, 425, 447, 463
Hemiaster, iii, 189
dalli, iii, 135
Hemimactra, iii, 292
Hemipristis serra, iii, 204
Hemipters, Jurassic, iii, 105
Hemlock formation, ii, 180
Henrietta formation, ii, 561
Henrys Fork formation, iii, 313
Herbertella sinuata, ii, 356
Herblvora, iii, 229
Pliocene, iii, 322, 323
Hercynian fauna, ii, 450
Hermitage formation, iii, 552
Hermosa formation, iii, 572
Herrick, C. L., cited, ii, 623
Hershey, O. H., cited, iii, 124,
201, 212, 310, 311, 314,
317.412
Hesperornis, iii, 183
regalis, iii, 182
Hesse sandstone, iii, 550
Heterangium, ii, 595
Hexacoralla, iii, 57, 83
High-latitude glaciers, i, 254
High-level Columbia, iii, 447, 449
Hilgard, E. W., cited, iii, 141,
302, 303, 308, 411
Hill, R. T., cited, ii, 435; i", 24,
59, 60, 107, 115, 116, 118,
142, 143, 163, 220, 244,
258, 273, 302, 309, 479*.
(and Vaughan), iii, 142, 143,
300
Hills, R. C., cited, iii, 154, 155,
206, 207, 209
Himalayas, snow-line in, i, 246
Hinde, G. J., cited, ii, 287
Hindia, ii, 408
Hinton formation, ii, 559
Hippar'ion, iii, 286
Hipparionyx proximus, ii, 458
Hippopotamuses, Pliocene, iii,
32^
Hippurlte limestone, iii, 169
Historical geology, i, i
Hitchcock, C. H., cited, iii, 361,
367, 370
Hoang-Ho delta, i, 202, 203
Hobbs, W, H., cited, iii, 9, ii,
14, 15, 23
Hog back, Dakota, iii, 146
Hog-backs, i, 142
Hogbb'm, A. G., cited, iii, 445
Holaster simplex, iii, 135
Holden, E. S., cited, i, 538
Holdenville shale, iii, 562
Hole, A. D., cited, iii, 334
Holland, W. J , cited, iii, 88
Hollick, A., cited, iii, 59, 114
Holmes, W. H., cited, i, 99; "i,
504-507
Holmia broggeri, ii, 296
fauna, ii, 245
Holocrystalline rock, i, 412
Holocystites adiapatus, ii, 403
Holograptus richardsoni, ii, 362
Holopea sweeti, ii, 299, 300
Holoptychius, ii, 488
flemingi, ii, 488
Holosiderites, i, 5
Hoist, N O., cited, iii, 370
Holyoke range, origin of, iii, 19
Homalonotus delphinocephalus,
ii, 409
Homacodon, iii, 236
Hominidae, iii, 289
Homo diluvii testis, iii, 290
Homomya austinensis, iii, 135
Honeycomb coral, Silurian, ii,4O7
Hook (along shore), i, 363
Hoosic schist, iii, 546
Hopkins, T. C., cited, ii, 324,
424, 562; iii, 560
Hopkins, W., cited, i, 322
Hoplites, iii, 134
angulatus, iii, 136
Hoplophoneus, iii, 253
Horizontal configuration of
coasts, due to deposition, i,
363, 364
due to wave erosion, i, 353
Hormotoma gracilis, ii, 353
Hornblende, i, 400, 463
Hornblende-granite, i, 415
Hornblendite, i, 417, 452, 470
Hornstone, i, 470
" Horseback," ii, 575
Horses, Eocene, iii, 235
evolution of, iii, 286, 288
Pleistocene, iii, 498
Pliocene, iii, 322
Horsetails, ii, 596 (see also
Equisetae )
Horsetown series, iii, 122, 160
Horsts, ii, 129, 131
Hoskins, L. M., cited, i, 219,
552, 581; (and Van Hise),
ii, 258
Hot springs, deposits of, i, 225
along faults in Lake Lahontan,
iii, 465
Howchin, W., ii, 273
Howe, E., (and Cross,) iii, 572
Howell, Capt., cited, i, 171
Hudson River formation, iii, 557
Hudson river, material in solu-
tion in, i, 1 08
Hugi, F. J., cited i, 321
Hull, E., cited, i, 636; iii, 522
Human dispersal, iii, 533
Human period, iii, 517
life of, iii, 530
Human provincialism and cos-
mopolitanism, iii, 540
Human relics burial of, iii, 510
Pleistocene, iii, 502
Humboldt ranges, iii, 69
Hume, W. F., cited, iii, 279;
(and Barron,) iii, 320
Humphreys, A. A., (and Abbot,
M. L.,) cited, i, 106, 202
Hunt, T. S., cited, ii, 157
Huntington, E., cited, iii, 424;
(andGoldthwait), iii. 313
Hunton limestone, iii, 563
Huronian, ii, 175
close of, ii, 177
Crystal Falls region, ii, 180
deformation at close of, ii,
177
erosion of, ii, 181
Marquette region, ii, 179
Mesabi district, ii, 180
north of Lake Huron, ii, 181
Penokee-Gogebic region, ii,
1 80
sections of, ii, 179
thickness of, ii, 176
Vermilion region, ii, 180
Hustedia mormoni, ii, 616, 617
Button, F. W., cited, ii, 159
Huxley, T. H., cited, i, 322; ii,
538
Hyalite, i, 463
Hyatt, A., cited, iii, 61, 91, 92
Hybocrinus tumidus, ii, 359
Hydration, i, 43, 222
disruption of rock by, i, in
Hydreionocrinus acanthoporus,
ii, 616
Hydro-atmospheric stage of
earth's history, ii, 118
Hydrophytes, geologic contri-
butions of, i, 667
Hydrosphere, i, 7 (see also
Ground- water and Ocean)
geologic activity of , i, 8
horizons of activity, i, 9
Hydrospheric stage, initiation of,
ii, 106
Hydrozoa, Cambrian, ii, 286
Hyena family, iii, 289
Hylobates leuciscus, iii, 326
Hymenocaris vermicauda, ii, 283
Hymenopters, Jurassic, in, 105
Hyolithes ii, 299, 300
americanus, 11, 284
Hyopotamus, iii, 253
Hypersthene, i, 400, 463
Hypertragulus, iii, 253
Hypisodus, iii, 253
Hypogene rockst i, 470
Hypopnous, ii, 650
Hypotheses of earth's origin, 11,3
gaseous, ii, 3
Laplacian, or Nebular, ii, 4
meteoritic, ii, 3, 13
planetesimal, ii, 3
600
INDEX.
Hypothyris cuboides, ii, 475. 476
Hypsipleura gregaria, iii, 136
Hypsometric hypotheses of gla-
cial climate, iii, 424
Hyracodon, iii, 253
Hyracotherium, in, 235
venticolum, iii, 235
Hyrochinus, iii, 235
Ice, glacial (see Glaciers)
ground, i, 119
of lakes, i, 389
of rivers, i. 118
Icebergs, i, 307
Ice-caps, i, 249, 250
Ice crystals, arrangement in
glacier ice, i, 311
Ice-fall, i, 264
Iceland spar, i, 463
Ice-sheet, Cordilleran, hi, 330,
332
Greenland, rate of move-
ment, iii, 430
Keewatin, iii, 330, 332
Labradorean, in, 330
stages in history of, iii, 358
work of, iii, 358
Ice-sheets, and continental bor-
ders, iii, 529
development and thickness of,
iii, 355
•distribution of, iii, 329
formations made by, iii, 359
map of, iii, 330
rate of growth of, iii, 429
slope of, iii, 356
Ichthyopterygians, Triassic, iii,
46
Ichthyosauria, iii, 42
Cretaceous, iii, 180
Jurassic, iii, 86, 87
Triassic, iii, 45, 46
Ichthyosaurus quadriscissus, iii,
88,89
Ichthyornis, iii, 182, 184
victor, iii, 184
Ictops, iii, 253
Idaho formation, iii, 299
Iddings, J. P., cited, i, 412, 451,
573, 614, 636; iii, 272;
(and Weed), iii, 156, 159
Idonearca antroso, iii, 187
nebrascensis, iii, 189
vulgaris, iii, 187
Ignacio quartzite, iii, 573
Igneous activity, Cretaceous, iii,
167
Eocene, iii, 212
Miocene, iii, 270
Pleistocene, iii, 459
Igneous intrusions and shear
zone, ii, 130
Igneous rocks, Animikean, ii, 184
Cambrian, ii, 252
Carboniferous, ii, 588
Comanchean, iii, 124
composition of, i, 395
Crazy mountains, iii, 168
Cretaceous, iii, 167
Deccan, iii, 171
Igneous rocks, Devonian, ii,
439
gases in, ii, 95
heavy and light crystals in, ii,
121
Huronian, ii, 192
Jurassic, iii, 67, 76
Keweenawan, ii, 192
leading mineral of, i, 399
Lower Carboniferous, ii, 515
Miocene, iii, 270
Newark, iii, 10
Oligocene in Europe, iii, 251
origin of, i, 393
Pleistocene, iii, 459, 477
Pliocene, iii, 310, 317
relations to stratified rocks, i,
16
Silurian, ii, 394
structural features of, i, 498
Triassic, iii, 10, 28
Iguanodon, iii, 99
Ilex, iii, 173
Illaenus americanus, ii, 349
Illinoian drift, iii, 383, 390
glacial stage, iii, 391
Illinois, lead in, ii, 337
zinc in, ii, 337
Ilmenite, i, 463
Ilyanassa, iii, 295
percina, iii, 294
Incrustation, i, 223
Independence shales, iii, 558
India, Archean of, ii, 159
Cambrian of, ii, 272
Cambrian fossils of, ii, 300
Cretaceous, Lower, iii, 129
Upper, iii, 170
Devonian of, ii, 448
Eocene of, iii, 217
Jurassic of, iii, 77
Miocene of, iii, 280
Pennsylvanian of, ii, 590
Permian of, ii, 634
Proterozoic of, ii, 215
Indian Territory, section of
strata in, iii, 562
Indiana, section of strata in, iii,
556
Infusorial earth, i, 470
Initial atmosphere, nature of, ii,
95
Initiation of vulcanism, h, 99
Inoceramus, iii, 91, 189, 190
vanuxemi, iii, 189
Inorganic deposits, in deep sea,
i, 380
Insectivora, iii, 229
Eocene, iii, 239
Insect life, Carboniferous, ii, 610
Devonian, ii, 494
Eocene, iii, 240
Jurassic, iii, 104
Mississippian, ii, 538
Oligocene, iii, 252
Ordovician, ii, 346
Interglacial epochs, iii, 383-393
life of, iii, 490
faunas, iii, 493
floras, iii, 493
Interior of earth, i, 14 (see also
Vulcanism)
densities, based on Laplace's
law. i, 564
heat of, i, 562, 564
pressures, i, 564
Interior heat, sources of, ii, 99
Intermittent springs, i, 235
Internal heat (see Internal tem-
perature)
Internal temperature, i, 562
affected by ground-water, i,
570
at center of earth, i, 571
on accretion hypothesis, i, 564,
567
on convection hypothesis, i,
559
on Laplacian hypothesis, i, 559
Intrusions, i, 591
locrinus subcrassus, ii, 359
lone formation, iii, 264, 317
Iowa, lead in, ii, 337
section of strata in, iii, 558
zinc in, ii, 337
lowan drift, iii, 383, 387, 390
glacial stage, iii, 391
Iphidea labradorica, ii, 297
Iron age, iii, 504
Iron in meteorites, ii, 27
Iron ore, Clinton, ii, 377
Cretaceous of Europe iii,
170
Lake Superior region, ii, 190
Lias, iii, 73
Lower Cretaceous of Europe
iii, 128
Middle Jurassic, of England,
i", 73
Pennsylvanian, ii, 580
Iron-ore beds, origin, i, 425
Iron oxide, i, 400
Iron pyrites, i, 463
Ironstone, i, 425, 470
Ironwood formation, ii, 186, 188
Irruptions, i, 591
Irving, R. D., cited, ii, 138, 145,
157, 182, 193, 195, *97, 205;
(and Van Hise), 180, 188,
198; iii, 344, 367
Ischadites, ii, 363
Ischyrodonta decipiens, ii, 354
Ishpeming formation, ii, 176, 186
Island glaciation, iii, 336
Isocardia, iii, 295
markoei, iii, 292
Isoclinal folds, i, 504
Isodectes, it, 650
Isoseismals, i, 532
Isostasy, ii, 200, 236
Isostatic adjustments due to
gradation, ii, 236
Isotelus gigas, ii, 351
maximus, ii, 349
Itacolumite, i, 470
Italy, Jurassic of, iii, 71
lateral moraines in, i, 303
Pliocene of, iii, 319
Triassic of, iii, 36
Izard limestone, iii, 561
INDEX.
601
Jackson Coal series, Hi, 553
Jacksonian formation, iii, 199
Jaekel, O., cited, iii, 89
Jagger, T. A.. Jr., cited, ii, 206;
iii, 566
Japan, Cretaceous, Lower, iii,
129
Cretaceous, Upper, iii. 170
Eocene of, iii, 217, 219
Miocene of, iii, 280
Pennsylvanian of, ii, 590
Jasper, i, 470
Jefferson limestone, ii, 153; iii,
70, 1 66
Jefferson, M. W., cited, i,
iQ3
Jennings formation, iii, 548
Jerseyan drift, iii, 383, 387
glacial stage, iii, 384
John Day basin, iii, 210
beds, iii, 247
fauna, iii, 283
Johnson, L., cited iii, 361
Johnson, L. C., (and Smith,)
cited, iii, in, 302
Johnson, S. W., cited, i, 109, 190,
665
Johnson, W. D., cited, iii, 143,
194, 269, 459, 476; (and
Russell), iii, 462
Johnston, R. M., cited, ii, 159
Johnston-Lavis, H. J., cited, i,
636
Joints, i, 510
causes of, i, 511, 531
compression, i, 514
effect on valleys, i, 150
tension, i, 514
Joints and erosion, i, 125
Judd, J. W., cited, i, 636
Judith River beds, iii, 152
Juglans, iii, 173
Juniata formation, iii, 548
Jura-Comanchean land verte-
brates, iii, 97
Jura, White, iii, 75
Jurassic ammonites, iii, 80, 81,
91, 92
beetles, iii, 105
belemnites, iii, 82, 91, 92
birds, iii, 102
brachiopods, iii, 85, 91, 92, 93
cephalopods, iii, 91, 93
conifers, iii, 94
corals, iii, 83, 84, 91, 94
crinoids, iii, 83, 84
crocodilians, iii, 100
crustaceans, iii, 85, 91
cuttlefishes, iii, 82
decapods, iii, 85
dinosaurs, iii, 94
dipters, iii, 105
echinoderms, iii, 92
echinoids, iii, 85
fauna of Arctic regions, Hi, 92
of Dakota province, iii, 93
of northern interior, iii, 92
of Pacific, iii, 91
fishes, iii, 85
flying reptiles, iii, 101
Jurassic foraminifers, iii, 85
gastropods, iii, 83
hemipters, iii, 103
hymenopters, iii, 105
insects, iii, 104
land life, iii. 94, 95
life, iii, 80
lizards, iii, 101
mammals, iii, 103
marine reptiles, iii, 86
ornithopods, iii, 99
pelecypods, iii, 82, 83, 91,
93
Jurassic period, iii, 59
American marine faunas of,
iii, 90
climate, iii, 79
close of, iii, 67
in Europe, iii, 79
geography of, iii, 78
marine life of, iii, 80
plant life of, iii, 94
Jurassic plesiosaurs, iii, 88
pterodactyls, iii, 102
radiolarlans, iii, 85
rhynchocephalians, iii, 100
sea-urchins, iii, 84
sponges, iii, 85
stegosaurs, iii, 99
Jurassic system, iii, 59
Africa, iii, 77
Alaska, iii, 67
Arctic regions, iii, 77
Asia, iii, 77
Australia, iii, 78
Borneo, iii, 78
Central America, iii, 78
coal of, iii, 78
Cuba, iii, 60
Europe, iii, 70
Extra-European, iii, 77
foreign, iii, 70
igneous rock of, iii, 67. 76
interior, iii, 60
Lower, Europe, iii, 72
Pacific coast, iii, 61
western interior, iii, 63
Madagascar, iii, 78
map of, iii, 62
marine, Texas, iii, 60
Mexico, iii, 60, 78
Middle, England, coal of, iii,
73
Middle, England, iron of, iii, 73
Middle, Europe, iii, 73
Middle, Pacific coast, iii, 63
Middle, western interior, iii,
63
New Zealand, iii, 78
Queensland, coal in, iii, 78
relation of Triassic to, iii, 47
South America, iii, 78
thickness, iii, 66
Upper, Europe, iii, 74
Pacific coast, iii, 64
west, iii, 59, 61
Jurassic teleosaurs, iii, 100
teleosts, iii, 86
thalattosuchians, iii, 100
turtles, iii, 100
Kaaterskill Creek, piracy of, u
105
Kalkowsky, E., cited, ii, 518-
Kame moraines, iii, 369
terraces, iii, 371
Kames, i, 307; iii, 368
serpentine, i, 306
Kanawha formation, ii, 559
River, i, 168
Kansan drift, iii, 383, 387, 390
glacial stage, iii, 388
Kansas section of Permian, ii,
622
Kansas, volcanic dust in, i. 23
Kaolin, i, 463
Karoo sandstone, ii, 650; Hi, 38
Kaskaskia fauna, ii, 529
limestone, ii, 561
series, ii, 500, 503, 561; iii, 556
Katamorphism, i, 446; ii, 142
Kaup. cited, iii, 324
Kayser, E., cited, ii, 270, 272,
339, 39i. 448, 515, 5i6,
5i7, 590, 627, 628, 630,
634, 635, 639; "i, 32, 33,
37, 38, 78, 171, 249; (and
Lake), ii, 271, 444
Keeler, C. C.. cited, ii, 43
Keewatin ice-sheet, iii, 330, 332-.
Keilhack, Li, 424
Keith, A., cited, i, 442, 444;
ii, 151, 152, 214, 254, 437;
iii, 17, 19, 549
Kellogg, D. S., cited, iii, 403
Kelvin, Lord, cited, i, 560, 583;
ii, 4, 8, 22, 52
Kemp, J. F., cited, ii, 205
Kenai series, iii, 248
Kennedy, Wm., (and Hayes,)
cited, iii, 200
Keokuk formation, ii, 561
Keratophyre, i, 470
Kersantite, i, 470
Kessler limestone, H, 562; iii»
560
Kettles in terminal moraine, iii,
365
Keuper formation, iii, 33
Keweenaw peninsula, geology
of, ii, 193
Keweenawan, ii, 192
composition of, ii, 192
deformative movements cf, ii,
194
thickness of, ii, 192
Keyes, C. R.. cited, i, 474; ii,
250, 433, SGI, 542, 553,.
575; i", 143
Kidd, D. A., cited, i, 313
Kilauea, i, 605
Kinderhook brachiopods, ii, 519-
cephalopods, ii, 521
corals, ii, 521
crinoids, ii, 519
fauna, ii, 519, 520
gastropods, ii, 521
pelecypods, ii, 521
series, ii, 500, 501, 561; iii,.
558
trilobites, ii, 521
602
INDEX.
Kindle, E. M., cited, ii, 386
King, C., cited, i, 560; ii, 210,
250, 308, 322, 435; in, 27,
66, 70, 205. 208, 209, 210,
213, 266, 274, 275, 298,
3". 313, 334. 336, 467, 472
King, F. H., cited, i, 220
Kingsmill.T. W.,(andSkertchly.)
cited, iii, 407, 424
Kiowa shale, iii, 118
Kitchi schist, ii, 149
Kittatinny base-level, i, 168
Knapp, G. fl., cited, iii, 113;
(and Weller), iii, 140, 187
Knife Lake slates, ii, 150, 180
Knight, C. R., cited, iii, 100, 176,
177, 325
Knight, W. C., cited, ii, 435,
505, 553, 621, 624; iii, 26,
64, IIQ, 146
Knobs in terminal moraine, iii,
365
Knorria, Mississippian, ii, 537
Knowlton, F. H., cited, iii, 132,
210, 266
Knox dolomite, ii, 150, 179,
316; iii, 548, 55i
Knoxville formation, iii, 122,
160, 577
Koipeto formation, iii, 28
Kokomo limestone, ii, 389
Kome series, iii, 132
Kona dolomite, ii, 150, 179
Kootenay formation, iii, 120, 121
Koti>, Dr., cited, i, 534; ii, 159
Krakatoa, i, 22, 610, 611, 618
Krogh, A., cited, ii, 666, 667;
ii, 440
Kummel, H. B., cited, i, 203;
iii, 10, 14, 16, 113, 523;
(and Weller), ii, 266
Kupferschiefer, ii, 629
Kutorgina cingulata, ii, 297
Labrador Archean, ii, 146
Labradorean ice-sheet, iii, 330
Labradorite, i, 400, 429, 464
Labyrinthodonts, ii, 607
Mississippian, ii, 538
Triassic, iii, 42
Laccolith, i, 500, 592
Lacustrine deposits, i, 388
Pleistocene, iii, 446
Laelaps, iii, 176
Lafayette formation, iii, 301, 449
altitude, iii, 302
color, iii, 304
constitution, iii, 303
distribution, iii, 302
erosion of, iii, 304
fossils, iii, 305
genesis, iii, 305
thickness, iii, 303
Lake, P., (and Kayser,) cited, ii,
271,444
Lake Agassiz, iii, 402
Algonquin, iii, 399, 401
Arkona, iii, 397
Bonneville, i, 360; iii, 455
Champlain, glacial, iii, 399
Lake Chicago, iii, 395, 397
Dana, iii, 399
Duluth, iii, 396
Huron, Proterozoic north of,
ii, 203
ice, i, 389
Iroquois, iii, 399, 401
Lahontan, iii, 463-465
Lundy, iii, 399
Maumee, iii, 395, 396, 397
Mono, iii, 467
Nipissing, iii, 402, 404
Pepin, i, 179
Saginaw. in, 397
Superior region, succession of
events in, ii, 200
Warren, iii, 399
Whittlesey, iii, 399
Lakes, i, 386-392
bayou, i, 192, 193
changes taking place in, i, 387
delta, i, 204
deposits in, i, 387
extinct, i, 388
formed by rivers, i, 191, 192,
198
ice of, i, 389
oxbow, i, 192, 198
Lakota sandstone, iii, 68, 566
Land animals, Comanchean, iii,
133
Cretaceous, iii, 175
Devonian, ii, 494, 495
Eocene, iii, 228
Jurassic, iii, 95
Miocene, iii, 283
Mississippian, ii, 537
Oligocene, iii, 253
Pennsylvanian, ii, 606
Permian, ii, 646
Pleistocene, iii, 495
Pliocene, iii, 321
Triassic, iii, 41
Land formations, Eocene, iii, 204
Land life, Carboniferous, ri, 606
Cretaceous, iii, 172
Devonian, ii, 490, 491
Eocene, iii, 228
Jurassic, iii, 94, 95
Miocene, iii, 283
Mississippian, ii, 537
Oligocene, iii, 253
Ordovician, ii, 346
Permian, ii, 646
Pleistocene, iii, 495
Pliocene, iii, 321
Triassic, iii, 41
Land periods, iii, 95
Landes, H., cited, ii, 506; Hi,
202, 271
Landslide, i, 231
topography of, i, 230
Landslip mountain, i, 230
Land-water life, criteria of, ii,
480
Land-waters, Devonian life of, ii,
480
Lane, A. C., cited, i, 557, 636;
i', 504, 540, 544. 548; iii,
553
Langley, S. P., cited, ii, 674, 677;
111,444; (and Abbot), in, 431
Laosaurus, iii, 99
Lapham, I. A., cited, iii, 361
Lapilh, i, 470
in sea, i, 381, 405
Laplace, Marqu.s de, cited, i,
564
Laplacian hypothesis, ii, 4
difficulties of, 11, 82
of earth's history, ii, 82
modification of, ii, 88
objections to, ii, 10
Laporta, cited, iii, 530
Lapworth, C., cited, ii, 340, 345,
364
Laramide range, iii, 163
crustal shortening due to fold-
ing, i, 549
Laramide system, iii, 163
Laramie epoch, deformation at
close of, iii, 166
faulting at close of, iii, 164
Laramie series, iii, 70, 152, 153,
154. 157. 1 66, 206, 566, 568,
570
thickness, iii, 153
Lariosaurus, iii, 45
balsami, iii, 46
Later Wisconsin glacial stage,
iii. 393
Lateral creep of continents, ii,
132
Lateral moraines, i, 266, 302
in Bighorn mountains, i, 303
in Italy, i, 303
in Uinta mountains, i, 303
in Wasatch mountains, i, 303
Lateral pressure, metamorphism
by, i, 448
Lateral spreading, ii, 233
Laterite, i, 470
Laurentian formation, ii, 141-
143
original area of, ii, 151, 204
Laurus, iii, 132
Lava cones, i, 608
Lavas, i, 612-616
and ground- water, i, 616
consanguinity and succession
of, i, 614
crystallization of, i, 402, 403
depth of source of, i, 616
modes of reaching surface, i,
631
origin of, i, 623-631
rhyolitic (flow) structure of,
i, 410
solidification of, i, 393
temperatures of, i, 615, 626
Lavas and underground water, i,
627
Lawson, A. C., cited, ii, 151, 157:
hi, 201, 263,310,481; (and
Palache), iii, 363
Lead in Illinois, ii, 337
in Iowa, ii, 337
in Missouri, ii, 337
in Ordovician, ii, 337
in Wisconsin, ii, 337
INDEX.
603
Leadville limestone, ii, 154, 506,
563; in, 571
Lebanon limestone, iii, 552
Lecanocrinus macropetalus, ii,
403
LeClaire limestone, iii, 558
Le Conte, J., cited i, 474, 549 ;
ii, 570; iii, 311, 312, 313,
314,315
Leda, iii, 403
clays, iii, 494
concentrica, iii, 292
parilis, iii, 243
Lee, W. T., cited, iii, 66, 119
Lee conglomerate, ii, 539, 559;
iii, 549
Lees, J, H., cited, iii, 146
Leffingwell, E. D. K., (and
Capps,) cited, iii, 334
Leidy, J., cited, ii, 534
Leiorynchus quadricostatus, ii,
528, 530, 532
Leipers formation, iii, 552
Leith, C. K., cited, ii, 146, 150,
180, 194
Lelean, P. S., cited, iii, 219
Lendofelic, i, 456
Lenfelic, i, 456
Leonard, A. G., cited, ii, 542
Leperditia dermatoides, ii, 283
Lepidocoleus jamesi, ii, 351
Lep.docystis moorei, ii, 359
Lepidodiscus cincinnatiensis, ii,
359
Lepldodendron, ii, 598, 602, 603
Devonian, ii, 493
Mississippian, ii, 537
Permian, ii, 643
sternbergii, ii, 602
Lepidolite, i, 464
Lepidosiren, ii, 487
Lepidostrobus sp., ii, 593
Lepocrinites gebhardii, ii, 455
Leptaceratherium, iii, 253
Leptaena rhomboidalis, ii, 367,
453,455,525
Lepterpeton dobbsi, ii, 609
Leptomeryx, iii, 253
Leptopora placenta, ii, 520
Lesley, J, P., cited, ii, 125; iii,
382
Lesleya, ii, 595
Leucite, i, 464
Leucophyre, i, 412, 453
Levees, breaking of, i, 188
miniature, i, 182
natural, i, 188
on alluvial cones, i, 182
Level of no stress, i, 561
Leverett, F., cited, iii, 362, 368,
382, 386, 389, 390, 391,
392, 393, 397, 398, 400,
401, 412, 494; (and Cham-
berlin), 382; (and Taylor),
396
Lewis, H. C., cited, iii, 14, 370,
382; (and Wright), 368
Lewis, Wm.,(and Clarke,) cited,
i", 154
Lewisian gneiss, ii, 158
Lewiston limestone, iii, 548
Leyden argillite, iii, 546
Lias, Asia, iii, 77
coal, iii, 73
Europe, iii, 72
fauna of Pacific coast, iii, 90
iron ore of, iii, 73
Norway, oil in, iii, 73
Lichads, Onondagan, ii, 467
Lichas incola, ii, 349
Lieber, O. M., cited, ii, 145
Life, i, 638-672
Archeozoic, ii, 137, 159
atmospheric effects of, i, 638-
644; ii, 115
Cambrian, ii, 276
chemical work of, i, 638-646
climatic adaptations in Pleisto-
cene, iii, 486
climatic effects of, i, 643
Cretaceous, iii, 172
Devonian, ii, 448
effects of glaciation on, iii, 483
effects on rock decomposition,
i, 130, 644
Eocene, general conditions of,
iii, 221
geologic effects of, i, 639
Human Period, iii, 530
influenced by environment, i,
666
inorganic rocks due to, i, 646
interglacial epochs, iii, 490
Jurassic, iii, 80
land, Cretaceous, iii, 172
man's influence on, i, 650
marine, Cretaceous, iii, 180
Jurassic, iii, 80
Pliocene, iii, 326
migrations of in Pleistocene
Period, iii, 485
Miocene, iii, 282
Mississippian, ii, 518
Oligocene, iii, 252
Ordovician, ii, 342
Permian, ii, 641
Pleistocene* iii, 483
Alpine remnants of, iii, 489
European, iii, 498
South America, iii, 500
Southern Hemisphere, iii,
500
Pliocene, iii, 320
protection against erosion, i,
130, 644
Proterozoic, ii, 217
Silurian, ii, 396
stage of initial, ii, in
Triassic, iii, 38
Life and carbon dioxide, i, 640,
642, 643
Lightning, effects of, L, 52
Lignite, i, 426, 470
Lignitic formation, iii, 199
Lima, iii, 91, 295
wacoensis, iii, 135
Limburgite, i, 470
Lime carbonate, deposition of, i,
375, 376
Lime Creek formation, iii, 558
Limestone, i, 378, 424, 434
Limestone caves of Kentucky, ii,
503
Limestone, crushing strength of,
ii, 127
dikes, iii, 263
formation and its effects on
atmosphere, ii, 660
Mississippian, ii, 662
origin of, i, 378, 654, 655
sinks, i, 227, 231
stratification of, i, 487
Limestone-forming animals, i,
660-662
plants, i, 654, 655
Limonite, i, 425
Lincoln, D. F., cited, iii, 362
Lindemuth, A. C., cited, iii, 370
Lindgren, W., cited, i, 474; ii,
555; iii, 28, 70, 265,274;
(and Drake), iii, 210, 212,
299; (and Turner), iii, 317
Lingula, iii, 92
brevirostra, iii, 93
flags, ii, 271
rectilateralis, ii, 356
umbona, ii, 616, 617
Lingulasma schucherti, ii, 356
Lingulella ccelata, ii, 297
Lingulepis pinniformis, ii, 299,
300
Linnarssonia transversa, ii, 298,
299
Linopteris, ii, 595
Liparase, i, 459
Liparite, i, 470
Lippincott, J. B., cited, iii, 264
Liquidamber, iii, 173
Lisbon earthquake, i, 533
Lithic eon, ii, 90
era, ii, 83
Lithosphere, i, 9-19
crust of, i, 13
irregularities of, i, 10
relief of, i, ii
size and shape of, i, 9
surface mantle of, i, 12
Lithostrotion canadense, ii, 530
Lithothamnion, iii, 294
Litopterna, iii, 321
Littoral currents, i, 342
deposits, i, 368, 369, 379
zone, i, 369
Liveridge, A., cited, ii, 24
Liverworts, geologic contribu-
tion of, i, 656
Livingston formation, iii, 156,
157, 159, 568
Livingstone, D., cited, i, 49
Lizards, Cretaceous, iii, 178
Jurassic, iii, 101
Triassic, iii, 43
Llamas, Pliocene^ iii, 322
Llanberis group, ii, 271
Llandeilo beds, ii, 342
Llandovery series, ii, 396
Load (of streams), i, 177-179
Lobocrinus longirostus, ii, 525
Localization of glaciation, iii,
433
694
INDEX.
Lockatong formation, iii, 10
Lockport limestone, ii, 370, 37?
Lockyer, N., cited, ii, 13, 40
Lodge moraine, i, 301
Lodore formation, iii, 313
Loess, i, 23, 470; iii, 405
age of, iii, 408
concretions, iii, 409
distribution, iii, 405, 407
fossils, iii, 409
Oregon, iii, 409
origin, iii, 409
structure, iii, 406
thickness, iii, 409
Washington, iii, 409
Logan, Sir W,, cited, ii, 151, 181,
566
Logan, W. N., cited, iii, 64, 66,
148, 149
Logan group, ii, 500, 560; iii,
554
Lone Mountain limestone, iii, 576
Longmeadow sandstone, iii, 546
Longwood shale, ii, 373
Lookout conglomerate, ii, 5391
iii, 55i
Loop (along shore), i, 357- 3^3
Lophiodonts, Miocene, iii, 284
Lophospira helicteres, ii, 353
Lorraine beds, ii, 310; iii, 553,
555
" Lost " interval, ii, 222
Lotorium, iii, 295
Loughridge, R. H., cited, iii, 302,
411
Louisiana limestone, ii, 561
Loup Fork beds, iii, 269
fauna, iii, 284
Lower Aubrey sandstone, iii, 313,
574
Lower Barren Coal Measures, ii,
542
Lower Burlington limestone, ii,
56i
Lower Cambrian, ii, 219, 241
distribution of, ii, 219
or Olenellus fauna, ii, 296
relations to Proterozoic, ii, 224
Lower Carboniferous (see Mis-
sissippian)
close of, ii, 516
European, ii, 511
igneous rock, ii, 515
Lower Carboniferous period, ii,
496
Lower Cretaceous system, iii,
108 (see also Comanchean)
Africa, iii, 129
Asia, iii, 129
Europe, iii, 126, 128
Foreign, iii, 125
South America, iii, 129
Lower Cross Timber formation,
iii, 142
Lower Forestian epoch, iii, 421
Lower Helderberg, ii, 418; iii,
556
Lower Magnesian limestone, ii,
3i5; i«, 557
Lower Permian of Europe, ii, 626
Lower Productive Coal Measures,
ii, 542
Lower Silurian (see Ordovician),
ii, 340
Lower Turbarian epoch, iii, 421
Low-level Columbia, iii, 447, 449
Lowville limestone, ii, 310
Loxonema hamiltoniae, ii, 471
leda, ii, 403
Lucas, F. A., cited, iii, 100, 182,
183
Lucina aquiana, iii, 243
cretacea, iii, 187
Ludlow series, ii, 396
Lumon clays, iii, 309
Lunar craters, i, 598
Lunatia marylandica, iii, 243
Lung-fishes, ii, 487
Lunn, A. C., cited, i, 552, 565,
566, 567, 572; ii, 102, 667,
Lutraria, iii, 295
Lycopodiales, Carboniferous, ii,
598
Devonian, ii, 493
Mississippian, ii, 537
Pennsylvanian, ii, 592
Lycopodites welthermianum, ii,
599
Lycopods, geologic work of, i,
657
Triassic, iii, 39
Lydekker, R., cited, iii, 320, 501 ;
(and Nicholson), i, 658
Lyell, Sir C., cited, i, 649 ; iii, 516
Lyginodendron, ii, 595, 596
Lyman, B. S., cited, iii, 14, 15
Lyriodendron, iii, 173
giganteum, iii, 174
Lyrodesma cincinnatiensis, ii,
354
Lyropora, ii, 531
Lytoceras, iii, 134
batesii, iii, 136
Macacus, iii, 324
MacBride, T. H., cited, iii, 494
Machaeracanthus, ii, 463
Machserodus, iii, 323
Mackenzie river, delta, i, 202
Maclurea arantiaca, iii, 491
logani, ii, 353
Macrocallista, iii, 295
Macrocephalites, iii, 92
Macrocheilus blaini, ii, 520
Macrodon missouriensis, ii, 521
Macrontella scofieldi, ii, 351
Macropetalichthys, ii, 463
sullivanti, ii, 462
Macrouras, iii, 85
Mactra, iii, 295
Madagascar, Jurassic of, iii, 78
Madison limestone, ii, 153; iii,
70, 157, 166, 568
sandstone, ii, 251
Magma, nature of, i, 401
Magnesite, i, 464
Magnesian limestone, iii, 561
Magnesium salts in sea, i, 377
Magnetic nodules in sea, i, 381
Magnetite, i, 464
Magnolia, iii, 173
pseudoacuminata, iii, 174
Malay peninsula, tin ores of, i,
478
Malaspina glacier, i, 254
Mallet, R., cited, i, 322, 537, 538,
628, 636
Mammals, Cretaceous, iii, 179
early home of, iii, 222
Jurassic, iii, 103
marine, Eocene, iii, 239
Pleistocene, iii, 496-498
South American, iii, 498
Triassic, iii, 44
Upper Jurassic, iii, 105
Mammoth, Pleistocene, iii, 491,
496
Mammoth Cave, i, 227
Mammoth hot springs, i, 654
Man as a geological agency, iii,
54i
dynasty of, iii, 533
glacial, in Europe, iii, 513
sources of good evidences
of, iii, 512
Neanderthal, iii, 326
Manasquan formation, iii, 140,
189
Manatash formation, iii, 267
Mancos formation, iii, 69
Manganese ore of Arkansas, ii,
337, 377
Manganiferous deposits, i, 384
Manlius limestone, i., 370
Mansfield sandstone, ii, 540; iii,
556
Manson, M., cited, iii, 445
Manti shale, iii, 210
Manticocsras, ii, 478
Mantle rock, i, 12, 422
Maquoketa shales, iii, 559
Marble, i, 447, 471
Marbut, C. F., cited, ii, 561 ; iii,
411
Marcasite, i, 464
Marcellus shale, ii, 429
Marine deposits, i, 355-363. 37O-
386
chemical, i, 367 375. 383
deep-sea, i, 368, 378-386
extra-terrestrial, i, 381
littoral, i, 368, 369
mechanical, i, 369, 380
organic, i, 375
Pleistocene, iii, 447, 476
shallow-water, i, 369-378
table of, i, 380
Marine faunas, Comanchean, iii,
134
Marine life, distribution of, i
328
Jurassic, iii, 80
Miocene, iii, 290
OHgocene, iii, 257
Pleistocene, iii, 494
Triassic, iii, 48
Marine periods, iii, 95
Marl, i, 471 (see also GreensanJ
marl and Shell marl)
formed by plants, i, 655
INDEX.
605
Marl, greensand (see Greensand
marl)
Maroon conglomerate, li, 154,
563; iii, 157. 570
Marquette region, Animikean in,
ii, 186
geology of, ii, 149
Huronian series of, ii, 179
Proterozoic of, ii, 176
Mars, atmosphere of, ii, 93
water on, ii, no
Marsh, O. C., cited, iii, 44, 59,
97. 98, 105, in, 119. 176.
177, 184, 208, 209, 228, 233,
326
Marshall sandstone, iii, 553
shale, ii, 562; iii, 560
Marsha lltown beds, iii, 187
Marsupials, Miocene, iii, 290
Marthas Vineyard, Miocene of,
iii, 260
Martin, cited, iii, 280
Martin, G. C., cited, ii, 619;
(and Clark), iii, 98
Martin limestone, iii, 575
Martinez formation, iii, 201
Martinia glabra, ii, 532
Martinique, i, 605
Martinsburg shale, iii, 548
Martite, i, 464
Marysville Buttes, California,
iii, 317
Maryville formation, iii, 550
Mascall formation, ii:, 266
Mason. W. P., cited, i, 107
Mass action, i, 478, 484, 554
Massachusetts, section of strata
in, iii, 546
Mastodon americanus, iii, 497
longirostris, iii, 324
Mastodons, Pleistocene, iii, 491,
496
Pliocene, iii, 322, 323
Mastodonsaurus giganteus, ii,
610
Matawan formation, iii, 140, 187,
449
Mather, W. W., cited, ii, 310. 371
Matson, G. C., cited, ii, 439
Matthew. G. F., cited, ii, 244,
280; iii, 361
Matthew, W. D., cited, iii, 195,
228, 246, 253, 286, 288, 289
Mature drainage, i, 86
Mature streams, characteristics
of, i, 86
Mauch Chunk shales, ii, 500,
502, 557, 558
Mauna Loa, i, 605, 606, 624
Maury. Miss C. J., cited, iii,
244. 257
Maxville limestone, ii, 500, 504,
560; iii, 554
Maxwell, C., cited, ii, 22, 34
Mayence basin, Pliocene, iii, 319
McAlester shale, iii, 562
McConnell, J. C., cited, i, 313,
322, 323, 549; ». 266
McConnell, R. G., cited, iii, 152,
165, 332
McElmo formation, iii, 69
McGee, W J, cited i, 59, 524;
ii, 108, in, 301, 302, 307,
3". 359, 370, 477. 494,
516; (and Call), iii, 411
McGregor, J. H., cited, ii 647,
649
Meander belt, relation to width
of stream, i, 193
Meanders, flood-plain, i, 190
intrenched, i, 164
of the Meuse, i, 164
of the Moselle, i, 164
of the Seine, i, 164
Mean sphere level, i, 548
Mecklenburgian epoch, iii, 421
Medial moraine, i, 266, 297
Medicinal springs, i, 235
Medina sandstone, ii, 370, 373,
398; iii, 554, 556
Medlicott, H. B., cited, i, 203;
ii, 159; (and Blanford), iii,
171
Medlicottia, ii, 654
copei, ii, 654
Medullosa, ii, 595, 596
Meek, F. B., cited, ii, 450; iii, 61
Meekella striatocostata, ii, 616,
617
Meekoceras, iii, 52, 53
Meekospira peracuta, ii, 616
Megaceratops, iii, 255
Megalonyx, iii, 322, 498
Megalopteris, Mississippian, ii,
537
Megaloxylon, ii, 595
Megatherium, iii, 322, 498
Melanopsis, iii, 295
Melaphyres, i, 412, 431. 453t 471
Melina, iii, 295
Melonites, ii, 530
Men of Spy. iii, 326
Menaccanite, i, 464
Mendelejeff, D., (and Moissan,)
cited, i, 646
Mendenhall, W C., (and Schra-
der,) cited, iii, 124
Mendon formation, ii, 212
Mendota limestone, ii, 251
Meneoian group, ii, 271
Mennell, F. P., cited, iii, 320
Menodus, iii, 255
Menominee, region, Animikean
of, ii, 187
Huronian of, ii, 197
geology of, ii, 149
Mental element, material effects
of, i, 649
Merced series, iii, 310, 316
Merchantville beds, iii, 187
Mercury, atmosphere of, ii, 93
Merriam, J. C., cited, iii, 46, 47,
122, 247, 266, 299
Merrill, F. J. H., cited, ii, 324;
(and Ries), iii, 403
Merrill, G. P., i, 35, in, 221
Merom sandstone, iii, 556
Merychippus, iii, 286
Mesabi district, ii, 150
Animikean of, ii, 189
Mesabi district, Huronian series
of, ii, 1 80
Mesas, i, 142
Mesaxonia, iii, 234
Mesnard quartzite, ii, 150, 179
Mesodectes, iii, 253
Mesohippus, iii, 253
Mesonacis vermontana, ii, 296^.
297
Mesontaric series, ii, 370
Mesophytes, i, 667
Mesopithecus, iii, 325
Mesosaurus, ii, 679
Meta-diabase, i, 471
Meta-igneous rock, i, 471
Metamorphic rocks, i, 17, 471
Metamorphism, i, 427 433, 440,
449
Archean, ii, 144
by heat, i, 446
by lateral pressure, i, 448
deep-seated, i, 449
Proterozoic, ii, 201
Metamynodon. iii, 253
Metcalfe, cited, iii, 324
Meteorites, i, 4; ii, 22
characters of. ii, 23
number of, i, 381
Meteorites and comets, common
minerals absent from, 11, 29,
iron in. ii, 27
origin of, ii, 23
relations of, ii, 36
swarm of. ii, 18
velocities of, ii, 16
Meteoritic gases, ii, 95
Meteoritic hypothesis of earth's
origin, ii, 13
Meteoritic hypothesis of earth's
origin, tenuity of celestial
matter under, ii, 19
Meteoritic state, origin of, ii, 15
Meteoritic swarm, initiation of,
ii, 1 6
Meuse, meanders of, i, 164
Mexico, Comanchean of, iii, 118
Jurassic of, iii, 60, 78
Mississippian of, ii, 556
Pennsylvanian of, ii, 556
Triassic of, iii, 23
Meyer, H. von, cited, iii, 103,.
104
Mica, i, 400, 464
Mica schists, i, 448
Michelinia, ii, 457
lenticularis, ii, 455
Michigamme formation, ii, 186,.
187
Michigan, section of strata in,
iii, 553
series, ii, 503
Microcline, i, 400, 464
Microconodon, iii, 45
Microdiscus speciosus, ii, 297
Microgranite, i, 471
Microlestes, iii, 45
Microlites, i, 407, 471
Microsauria, ii, 607, 608
Middle Cambrian, ii, 224, 241
Middle Devonian, ii, 424
606
INDEX.
Middle Devonian, ii, 424
geographic changes during, ii,
430
in the northwest, ii, 429
Middle Ordovician fauna, ii,
365
Middle Silurian fauna, ii, 399
foreign relations, ii, 409
Middle Triassic faunas, iii, 54
Midwayan formation, iii, 199
Migration of climatic zones in
Pleistocene, iii, 486
of dunes, i, 33
of life in Pleistocene, iii, 485
of plants, rate of, in glaciated
area, iii, 533
Miliola, iii, 241
Milky Way, ii, 53
Millsap division, ii, 563
limestone, ii, 506
Millstone grit, ii, 539, 562; iii,
560
Milne, J., cited, i, 533, 537, 538,
583; (and Burton), 636;
(and Gray), 578
Mineral matter in sea, i, 324-326
amount of, i, 325
Minerals, felspathic, i, 400, 462
formation of, i, 397, 612
of igneous rocks, i, 399
list of, i, 460-467
Mineral springs, i, 235
Minette, i, 415, 471
Mining geology, i, i
Minnehaha Falls, i, 137
Minnekahta limestone, iii, 68,
565, 566
Minnelusa sandstone, iii, 68,
567
Minnesota, Archean of, ii, 150
Minnewaste limestone, iii, 566
Miocene amphibians, iii, 290
anoplotheres, iii, 284
anthrocotheres, iii, 284
birds, iii, 290
bison, iii, 286
caenotheres, iii, 284
camels, iii, 286
carnivores, iii, 284, 289
cephalopods, iii, 294
cetaceans, iii, 294
Chesapeake, fauna, iii, 291
corals, iii, 294
crustaceans, iii, 294
deer, iii, 285
echinoids, iii, 294
elotheres, iii, 284
fauna, iii, 283
foraminifers, iii, 294
gastropods, iii, 293, 294
grasses, iii, 283
land animals, iii, 283
land plants, iii, 282
lophiodonts, iii, 284
marsupials, iii, 290
opossums, iii, 290
oreodons, iii, 284
pelecypods, iii, 292, 293
Miocene Period, iii, 258
climate, iii, 261,281
Miocene Period, climate, Green-
land, iii, 281
close of, iti, 273, 279 .*,
crustal movements, in Europe,
iii, 280
deformation during, iii, 273
igneous activity, iii, 270
life, iii, 282
marine life, iii, 290
Miocene perissodactyls, iii, 284
primates, iii, 289
proboscidians, iii, 284
protocerases, iii, 284
rays, iii, 294
reptiles, iii, 290
rodents, iii, 284
ruminants, iii, 285
scaphopods, iii, 294
sharks, iii, 294
Miocene System, Atlantic coast,
iii, 258
Arctic latitudes, iii, 281
Asia, iii, 280
auriferous gravels of Califor-
nia, iii, 265, 274, 299
Australia, iii, 280
British Columbia, ifl, 270
California, oil in, iii, 263
Europe, iii, 276
Gulf coast, iii, 261
map, iii, 259
Martha's Vineyard, iii, 260
New Zealand, iii, 281
Pacific cast, iii, 262
petroleum, iii, 279
South America, iii, 281
Texas, iii, 262
Texas, oil in, iii, 262
thickness of, iii, 266
Miocene tapirs, iii, 289
Truckee formation, iii, 266
vermes, iii, 294
xiphodonts, iii, 284
Miolabis, iii, 286
Mirlic rocks, i, 458
Mississippi river, delta, i, 197,
202
depth of channel, i, 171
flood-plain, i, 194
lakes of, i, 192
floods of, i, 188
levees of, i, 188
material in solution in, i, 108
sediment carried by, i, 106
Mississippian amphibia, ii, 527
fauna of Great Basin, ii, 527
fishes, ii, 534
labyrinthodonts, ii, 538
land life, ii, 537
life of, ii, 518
Mississippian Period, ii, 496, 507
climate of, ii, 518
igneous activity of, ii, 507
Mississippian sharks, ii, 535
system, subdivisions of, ii, 500
system, thickness of, ii, 510
west of Great Plains, ii, 505
Missouri, lead in, ii, 337
Missouri river, scour-and-fill of,
i, 195
Missouri series, ii, 542, 561 ; Hi,
558
Missouri, zinc in, ii, 337
Mitchell limestone, iii, 556
Mitic rocks, i. 456
Mitra potomacensis, iii, 243
Mitrocystis mitra, ii, 359
Moccasin limestone, ii, 316
Modes of deformation under
planetesimal hypothesis, ii,
123
Modified hypothesis of earth's
history, stages under, ii, 90
Modiola, iii, 91
Modiolopsis arguta, ii, 354
Modiolus alabamensis, iii, 243
dalli, iii, 292
Moeritherium, iii, 284
Mohawkian system, ii, 310
Moissan, H., cited, i, 646
Mojave formation, iii, 210
Molas formation, iii, 572
Molasse formation, iii, 250, 276
Molengraaf, G. A. F., cited, ii,
636; iii, 172, 320
Molgophis, ii, 608
Molluscoidea (see Brachiopods)
Cambrian, ii, 284
geologic contribution of, i, 662
Mollusks, Carboniferous, ii, 615
Comanchean, iii, 134
Cretaceous, iii, 187
Devonian, ii, 454, 459, 465,
473
Eocene, iii, 243
Genevieve, ii, 533
Geologic contributions of, i,
662
Jurassic, iii, 93
Miocene, iii, 292, 294, 295
Mississippian, ii, 521 , 527, 528,
533
Oligocene, iii, 257
Ordovician, ii, 352
Oriskany, ii, 459
Permian, ii, 653
Pleistocene, iii, 494
Pliocene, iii, 326
Silurian, ii, 405
Triassic, iii, 53
Molten eon, ii, 90
interior, lava from, i, 624
magmas, nature of, i, 401
reservoirs, lavas from, i, 624
zone, middle, ii, 8
Moment of momentum of
planets, ii, ii
Mona schist, ii, 149, 150
Monadnocks, i, 145
Monarch formation, iii, 568
Monkeys, Pliocene, iii, 322
Monmcuth formation, iii, 140,
189
Monoclinal shifting, i, 127
Monocline, i, 504
Monocotyledons, Cretaceous, iii(
173
introduction of, iii 175
Monongahela series, ii, 542, 557»
558,56o; iii, 554
INDEX.
607
Monopteria loogispina, ii, 616
Monroe formation, iii, 553, 554
Montana fauna, iii, 190
formation, iii, 70, 142, 151,
I53-I55. 157, 166, 568,
570
section of strata in, iii, 568
Monterey sandstone, iii, 577
series, iii, 68, 262, 263, 316
shale, iii, 548
Montezuma schist, ii, 152
Monticulipora, ii, 357
arborea, ii, 358
Monzonite, i, 471
Moon, i, 3, 598
Moraine plains, iii, 372
Moraines, dump, i, 301
ground, i, 302; iii, 360
lateral, i, 266, 302
lodge, i, 301
medial, i, 266, 297
molluscan shells in, i, 297
push, i, 301
recessional, iii, 367
surface, i, 266
terminal, i, 266, 301; iii, 362
types, i, 301
Moricke, W., (and Steinman,)
cited, iii, 281
Morita formation, iii, 575
Morrison formation, iii, 68, 97,
119, 206, 565, 566 (see
also Como)
origin of, iii, 120
position of, iii, 66
Mortar beds, iii, 300
Mosasaurians, Cretaceous, iii,
1 80
Moseley, H., cited, i, 322
Moselle River intrenchment me-
anders, i, 164
Moss, cited, iii, 440
Mosses, geologic contributions
of, i, 656
Moulton, F. R., cited, i, 565;
ii, 4, 10, ii, 17, 38, 54,
57, 62, 63, 65, 72
Mount Erebus, i, 603
Hecla, ii, 603
Holly formation, ii, 213
Shasta, i, 611
Terror, i, 603
Toby conglomerate, iii, 546
Mountain-forming movements,
i, 542
Mountain glaciation of glacial
period, iii, 333
Mountain limestone, ii, 558
Mountains, serration of, i, 48,
So
Movements, crustal, at close of
Cretaceous, iii, 162
Europe, Miocene, iii, 280
Movements of earth's body, i,
526-589
causes of, i, 551-557
continent-forming, i, 544
distribution in time, i, 545
epeirogenic, i, 537
folding, i, 545
Movements of earth's body,
minute and rapid, i, 526
mountain-forming, i, 542
erogenic, i, 537
Pliocene, iii, 316
periodic, i, 542
plateau-forming, i, 543
relation of vertical and hori-
zontal, i, 545
slow and massive, i, 537
Movements of glaciers, i, 259,
261,299,313-323
of sea-water, i, 334-342
causes of, i, 334-339
Mud-cracks, i, 489
Mud-flows, volcanic, i, 610
Mud-rain, i, 25
Mudstone, i, 471
Muensteroceras oweni, ii, 520
Mugge, O., cited, i, 313, 322,
323
Muir glacier, i. 259
Mulinia, iii, 295
Mural limestone, iii, 575
Murchison, R. I., cited, ii, 340
Murchisonia, Onondagan, ii,
466
Murex, iii, 294
Murray, A., cited, iii, 336
Murray. Sir John, cited, i, ii,
215. 325, 326, 369, 604, 655
Murray shale, iii, 550
Muschelkalk formation, iii, 32
Muscovite, i, 400, 464
Musk-ox, Pleistocene, iii, 498
Mustek, iii, 289
Mustelidae, iii, 237
Mya, iii, 403
Myacites humboldtensis, iii, 53
Myalina recurvirosiris, ii, 616
Mylodon, iii, 322, 498
Myophoria alta, iii, 53
Myrica, iii, 133, 173
longa, iii, 174
Myriopods, Carboniferous, ii,6n
Devonian, ii, 495
Myrtle formation, iii, 161, 202
Mytiloconcha, iii, 295
Mytilus, iii, 91
formation, iii, 310
whitei, iii, 92, 93
Naco limestone, iii, 575
Nanjemoy formation, iii, 199
Nanosaurus, iii, 99
Nansen, F., cited, iii, 357, 442,
522
Naosaurus, ii, 649
Naphtha, Pliocene, iii, 318
Narragansett Bay coal, ii, 549
Narrows, i, 141
Nashville dome, ii, 335
Nassa marylandica, iii, 294
Natchez formation, iii, 386
Nathorst, A., cited, ii, 298
Naticidae, iii, 134
Naticopsis altonensis, ii, 616
Natural bridges, i, 153, 231
of Virginia, i, 156
on coasts, i, 351
Natural gases, i, 646
Natural levees (see Levees)
Natural oils, i, 646
Nautiloids, Triassic, iii, 56
Nautilus, iii, 294
family, Hamilton, ii, 473
Mississippian, ii, 525
Onondagan, ii, 466
meekanum, iii, 189
Navarro formation, iii, 142,
143
Neanderthal man, iii, 326
Nebo sandstone, iii, 550
Nebraska, section of strata in,
iii, 564
volcanic dust in, i, 23
Nebulae, aggregate molecular, ii,
42
characteristics of, ii, 41
existing, ii, 12
free-molecular, ii, 41
luminescence of, ii, 59
origin of, ii, 21
plane tesi ma 1, ii, 48
spiral form dominant, ii, 43
Nebular hypothesis, ii, 4
difficulties of, ii, 84, 86
earth's history under, ii, 90
modification of, ii, 88
Negaunee formation, ii, 150, 176,
179, 180
Neihart quartzite, iii, 569
Neocomian stage, iii, 128
Neolithic age, iii, 502
Neoliths, iii, 503
Neontaric series, ii, 370
Neotremata, ii, 356
Nephelinite, i, 471
Nephelite, i, 400, 464
Neptunella intertextus, iii, 189
Nerinea, iii, 91, 134
Nerium, iii, 173
Nervita, iii, 294
Neudeckian epoch, iii, 421
Neumayr, M., cited, ii, 444, 446;
iii, 66, 75, 78, 79, 92, 94»
107, 129, 172, 220, 221
Neuinayria, iii, 92
henryi, iii, 93
Neuropteris, ii, 595, 602
angustifolia, ii, 593
auriculata, ii, 593
decipiens, ii, 594
valida, ii, 645
vermicularis, ii, 593
Nevada, Eureka district, section
of strata in, iii, 576
Nevada limestone, iii, 576
Nevadite, i, 471
Neve, i, 246
Neverita, iii, 294
New Albany shale, iii, 556
New Brunswick, Ordovician of,
ii, 336
New Red Sandstone, ii, 628; iii,
34
New Richmond sandstone, iii,
559
New River, i, 168
New Stone Age, iii, 502
608
INDEX.
New York, map of western, ii, 394
New Zealand, Cretaceous, iii, 172
Jurassic, iii, 78
Miocene, iii, 281
Oligocene, iii, 252
Newark series, iii, 2
coal, iii, 17
correlation, iii, 17
faulting, iii, 12
former extent, iii, 9
igneous rocks, iii, 10
origin, iii, 7
physiography of, iii, 19
structure, iii, n
subdivisions, iii, 10
thickness, iii, 17
Newberry, J. S., cited, ii, 461,
534. 535, 566, 614; iii, 40,
120, 133, 370
Newcomb, S., cited, ii, 16
Newfoundland, glaciation, iii, 336
Newland limestone, iii, 569
Newman limestone, ii, 502, 559;
iii, 549
Newsom, J. F., cited, i, 514
Newton, H., cited, iii, 25, 148
Niagara Falls, i, 139
age, iii, 415
recession of, i, 139
Niagara fauna, ii, 389
formation, ii, 377; iii, 553,
554, 556
River, i, 120
series, ii, 370, 375
Nichols shale, iii, 530
Nicholson, A., (and Lydekker,)
cited, i, 658
Nickles, J. M., cited, ii, 310
Nicola formation, iii, 28
Nile River, delta of, i, 202
material in solution in, i, 108
sediment carried by, i, 107
Niobrara chalk, iii, 143
formation, iii, 148, 564, 566,
570
Nitikin, S., cited, iii, 92
Nitrogen and life, i, 642
Nodosaria bucillum, iii, 241
communis, iii, 241
Nodules, i, 471
Noeggerathiopsis hislop, ii, 645
Nolichucky shale, iii, 550
Nomenclature of rocks, i, 449
new system of, i, 451
Non-glacial Pleistocene forma-
tions, iii, 446
of interior, iii, 454
Nordenskjb'ld, A. E., cited, iii, 281
Norfolkian epoch, iii, 421
Norite, i, 471
Normal faulting, ii, 235
origin of, ii, 131, 132
Normal faults, i, 517
North America, average eleva-
tion of, i, 106
centers of glaciation, iii, 330
North Carolina, Triassic flora of,
iii, 40
Northern Interior coal-field, ii,
548
Norton, W. H., cited, ii, 424
Norton formation, ii, 559
Norway, Archean in, ii, 158
Cambrian glaciation in, ii, 272
Lias, oil in, iii, 73
Norwich crag, iii, 318
Nosite, i, 465
Nothosauria, iii, 42
Triassic, iii, 45
Notidanus primigenius, iii, 294
Nova Scotia, Clinton formation
of, ii, 375
glaciation, iii, 336
Ordovician, ii, 336
Nova Scotia-New Brunswick
coal-field, ii, 548
Novaculite, i, 471
Novae, ii, 41
Nuclear growth, ii, 78
stage of earth's history, ii, 92
Nucleocrinus verneuili, ii, 463
Nucula ovula, iii, 243
Nuculidae, iii, 295
Nummulites, i, 661 ; iii, 242
Nummulttic limestone, iii, 217
Nussbaum formation, iii, 206, 300
Nyctosaurus, iii, 179
gracilis, iii, 179
Oakville beds, iii, 262
Oblique fault, i, 525
Obolella gemma, ii, 285
polita, ii, 299, 300
Obsidian, i, 407, 453, 471
Ocean, the, i, 7, 324-392
changes in, i, 329
composition of, i, 324
diastrophism in, i, 329
gradation in, i, 333
salts of, i, 324
volume of , i, 8
vulcanism in, i, 332
work of, i, 324-392
Ocean and carbonic acid gas,
iii, 438
Ocean basin segments, size, i, 547
Ocean basins, i, ii
areas of, i, 7
connection of, i, 8
deposits on, i, 368-386
origin of, ii, 106-111
relief of bottom, i, ii
topography of, i, 326
Oceanic circulation, Permian, ii,
669
deposits, chemical, i, 375
deep-sea, i, 368, 378-386
organic, 1,375,382
shallow water, i, 369-378
era, ii, 83
Ocostephanus, iii, 92
Odontocephalus aegeria, ii, 463
Odontopleura crosotus, ii, 349
Odontopteris, ii, 595
cornuta, ii, 593
Oecotraustes, iii, 92
Oenonites rostratus, ii, 363
Offset with gap, i, 525
Offset with overlap, i, 525
Ogalalla formation, iii, 300, 564
Ogishkee conglomerate, ii, 150,
180
O'Hara, C. C., cited, ii, 420, 500
Ohio formation, iii, 156, 157, 570
section of strata in, iii, 554,
555
shale, iii, 554
Oil, California, iii, 201, 263
Colorado, iii, 152
Eocene, iii, 201
Indiana, ii, 336
New York, ii, 440
Norway, iii, 73
Ohio, ii, 336
Pennsylvania, ii, 443
Texas, iii, 262
West Virginia, ii, 440
Old Red Sandstone, ii, 444
Oldham, R. D., cited, i, 534, 535;
ii, 590, 635; iii, 171,280
Oldhamia, ii, 279
Olenellus, ii, 296, 300
Cambrian, ii, 241
fauna, ii, 240, 296
gilberti, ii, 296, 297
Olenoides curticei, ii, 298, 299
Olentangy shale, iii, 554
Olenus fauna, ii, 241
Oligocene amber, iii, 251
carnivora, iii, 253
elotheres, iii, 255
fauna, iii, 257
land animals, iii, 253
rhinoceroses, iii, 254
vegetation, iii, 252
Oligocene epoch, iii, 242
Aquitanian stage, iii, 250
life of, iii, 252
marine life of, iii, 257
Stampian stage, iii, 250
Tongrian stage, iii, 250
Oligocene System, Africa, iii, 252
Europe, iii, 248
Europe, coal of, iii, 250
igneous rocks of, iii, 251
New Zealand, iii, 252
Panama, iii, 252
South America, iii, 252
Vienna basin, iii, 250
Oligoclase, i, 400, 465
Oligoporus, ii, 530
mutatus, ii, 525
Oliva, iii, 294
litterata, iii, 294
Oliver, cited, ii. 595
Olivine, i, 400, 465
Omeose, i, 459
Omphacite, i, 465
Oncoceras pandion, ii, 352
Oneida conglomerate, ii, 370, 371
Oneota formation, iii, 559
Onondagan annelids, ii, 467
arthrodirans, ii, 461
brachiopods, ii, 464
bryozoans, ii, 467
cephalopods, ii, 465
corals, ii, 463
crinoids, ii, 464
crossopterygians, ii, 461
fauna, ii, 452, 460, 462
INDEX.
609
Onondagan fish, ii, 460
formation, ii, 418, 424
ganoids, ii, 461
protozoans, ii, 467
sharks, ii, 461
sponges, ii, 467
trilobites, ii, 467
Ontario (see Silurian)
Onychodus, ii, 463
Onyx, i, 471
Oolite, i, 435, 47 1, 496
Oolitic series, iii, 73
Ooze, i, 471
Opal, i, 465
Opeche shale, iii, 68, 565, 566
Operculina, iii, 241
Ophileta complanata, ii, 353
primordialis, ii, 299
Opis, iii, 91
Opossums, Miocene, iii, 290
Orbitoides, iii, 241
Orbitolites, iii, 241
Ordovician annelids, ii, 361, 363
Appalachian sections of , ii, 315
brachiopods, ii, 355, 356
bryozoans, ii, 357
cephalopods, ii, 352
classification of, ii, 310
climate of , ii, 342
coelenterates, ii, 360, 361
corals, ii, 360, 361
crinoids, ii, 359
Crustacea, ii, 351
echinoderms, ii, 357, 359
economic products of, ii, 336
of Europe, ii, 338
fauna, extra- American, ii, 367
foreign, ii, 338
gastropods, ii, 353, 354
graptolites, ii, 344, 362
igneous rocks of, ii, 322
insect life of, ii, 346
land life of, ii, 346
lead in, ii, 337
life, ii, 342, 343, 346
manganese ore in, ii, 337
New Brunswick, ii, 336
Nova Scotia, ii, 336
outcrops of, ii, 331
pelecypods, ii, 354
period, close of, 332
period, formations and physi-
cal history of, ii, 304
period, sedimentation of, ii,3O4
phosphates of Tennessee, ii,337
position of beds, ii, 322
protozoa, ii, 361
sections of, in interior, ii, 319
sponges, ii, 363
strata, condition of, ii, 324
succession of faunas, ii, 364
system, exposure of, ii, 326
Taconic mountains, ii, 326
thickness of, ii, 330
trilobites, ii, 347/"35i
Upper, fauna, ii, 367
Upper Mississippi section, ii,
313
vertebrates, ii, 347
•western sections, ii, 322
Ordovician, wide-spread lime-
stone of, ii, 321
zinc in, ii, 337
Ore deposits (see Ores)
Ore regions, origin of, i, 477
Oregon, loess in, iii, 409
O'Reilly, J. P., cited, i, 538
Oreodons, Eocene, iii, 236
Miocene, iii, 284
Oreopithecus, iii, 289
Ores, i, 428, 474-485
concentration by reprecipita-
tion, i, 479
concentration by solution, i,
479
concentration by surface
leaching, i, 478
" flaxseed," i, 497
influence of rock walls on
deposition, i, 484
magmatic segregation, i, 475
marine segregation, i, 476
original distribution, i, 475
purification by leaching, i, 478
residual concentration, i, 478
Organic processes, i, 638
residue, i, 640, 641
rocks, i, 449, 646
Organ-pipe coral, Silurian, ii, 407
Origin and descent of rocks, i,
393-484
Original crust, ii, 84
heat distribution, i, 559-568
material of earth, importance
of, ii, 119
Oriskany brachiopods, ii, 458,
459
corals, ii, 459
crinoids, ii, 459
fauna, ii, 451, 457
fish, ii, 459
formation, ii, 422
mollusks, ii, 459
trilobites, ii, 459
Ornithopoda, iii, 97
Cretaceous, iii, 178
Jurassic, iii, 99
Orogenic movements, i, 537
Orohippus, iii, 235
Orophocrinus stelliformis, ii, 525
Orthacanthus, ii, 614
Orthis, ii, 456, 472
tricenaris, ii, 356
Orthoceras annulatocostatum, ii,
532
annulatum, ii, 403, 409
bilineatum, ii, 352
blackei, iii, 53
cribrosum, ii, 616
Permian, ii, 655
sociale, ii, 352
Orthoceratites, Triassic, iii, 56
Orthoclase, i, 400, 465
Orthodesma rectum, ii, 354
Orthophyre, i, 471
Ortmann, A. E., cited, iii, 281
Orton, E., cited, ii, 336, 440,
560
Ortonia minor, ii, 363
Osage blastoids, ii, 525
Osage brachiopods, ii, 525
coral, ii, 525
crinoids, ii, 525
echinoids, ii, 525
fauna, ii, 522, 524
formation, ii, 500, 501; iii,
558
sponges, ii, 525
Osars, i, 306; iii, 374
Osborn, H. F., cited, ii, 647;
iii, 119, 207, 228, 237, 238,
255, 284
Osteolepis, ii, 489
Ostracoderms, ii, 537
Devonian, ii, 482-486
Ostracodes, Devonian, ii, 490
Silurian, ii, 408
Ostrea, iii, 82, 295
carolinensis, iii, 292
compressirostra, iii, 243
deltoidea, iii, 83
larva, iii, 189
soleniscus, iii, 189
strigilecula, iii, 92, 93
Ostreidae, iii, 134
Oswayo formation, ii, 557
Oswegan series, ii, 370, 371
Otoceras, iii, 49, 52
Otocoelus, ii, 650
Otozamites, iii, 39
carolinensis, iii, 41
Oudenodon trigoniceps, iii, 42
Ouray limestone, ii, 506; iii, 573
Outcrops, effects of faults on, i,
522
Outward flow of heat, and melt-
ing due to, ii, 102
Outwash plains, i, 306; iii, 372
subaqueous, iii, 372
Overloading of streams, i, 177,
178, 1 86
Overthrust, i, 518
in Scotland, ii, 341
Overwash plains, iii, 372
Owen, R., cited, iii, 324
Oxbow lakes, i, 192, 198
Oxidation, i, 42, 427
Oxinea mortoni, iii, 187
Oxmoor sandstone, iii, 551
Oxydactylus, iii, 286
iongipeS;, iii, 287
Oxymeris, iii, 294
Oxyrhina, iii, 294
Oxytonia, iii, 91
Ozarkian period, iii, 311
Ozocerite, i, 465, 646
Pachydiscus, iii, 134
Pachynolophus, iii, 235
Pacific coast, Comanchean, iii,
122
Cretaceous, iii, 160
Cretaceous fauna, iii, 190
Eocene, iii, 200
Liassic fauna, iii, 90
Lower Jurassic, iii, 61
Middle Jurass'c, iii, 63
Middle Jurass'c, fauna, iii, 91
Miocene, iii, 262
Pliocene, iii, 309
610
INDEX.
Pacific coast, Triassic, iii, 27
Upper Jurassic, iii, 64
Packard, A. S., cited, iii, 494
Pahasapa limestone, iii, 68, 567
Paidopithex, iii, 324
Palache, C., (and Lawson,) cited,
iii, 263
Palaeacis obtusum, ii, 525
Palaeaspis americana, ii, 413, 417
Palaeaster simplex, ii, 359
Palseocaris typus, ii, 614
Palaeohatteria, ii, 648, 649
longicaudata, ii, 647
Palseolagus, iii, 253
Palaeomastodon, iii, 284
Palaeoneile constricta, ii, 471
Palaeophonus, ii, 417
caledonicus, ii, 413
Palseopteris, ii, 602
Palseosauropus primaevus, Mis-
sissippian, ii, 537
Palasospondylus gunni, ii, 486
Paleolithic age, iii, 502
Paleoliths, iii, 503
Paleoniscus, ii, 652
macropomus, ii, 652
Paleontaric series, ii, 370
Paleontologic geology, i, i
Paleontology, i, i
based on stratigraphy, ii, 242
Paleozoic era, close of, ii, 639
Palisade Ridge, origin, iii, 19
Palissya, iii, 39
sphenolepis, iii, 41
Palms, Cretaceous, iii, 173
Palms formation, ii, 188
Pamunkey series, iii, 198, 449
Panama, Comanchean, iii, 124
Oligocene, iii, 252
Panopea, iii, 295
decisa, iii, 187
Panther Creek coal basin, ii, 577
Pantylus, ii, 650
Paphia, iii, 295
Parabolic velocity, ii, 55
Paradoxides bohemicus, ii, 298
Cambrian, ii, 241
Middle Cambrian fauna, ii,
298
Paraffine, i, 646
Paralegoceras newsomi, ii, 616
Paranassa percina, iii, 294
Paraphorhynchus striatocosta-
tus, ii, 520
Parasmilia texana, iii, 133
Paraxonia, iii, 234
Pareiasauria, ii, 648
Pareiasaurus, ii, 649
serridens, ii, 650
Pariotichus, ii, 650
Paris basin, Eocene of, iii, 215,
217
Oligocene of, iii, 249
Tertiary of, iii, 217
Parma sandstone, ii, 540; Hi, 553
Pascadero series, iii, 263
Pascagoula formation, iii, 262
Paso Robles formation, iii, 264,
310, 577
Patagonian beds, iii, 281
Patapsco formation, iii, 114
Patriofelis, iii, 237, 239
Patten, W., cited, ii, 482, 483,
484, 485, 613
Patuxent formation, iii, 59
Payette formation, iii, 210, 299
Peach, B. N., cited, ii, 495
Peale, A. C., cited, iii, 70, 157,
210, 267, 268
Peary, R. E., cited, iii, 442
Peastone, i, 472
Peat, i, 406, 472
composition of, ii, 569
Peccaries, Miocene, iii, 286
Pecchiolia, iii, 295
Pecopteris, ii, 644
tenuinervis, ii, 643
unita, ii, 593
Pecora, iii, 236
Pecten, iii, 91, 295
choctavensis, iii, 243
complexicosta, iii, 136
deformis, iii, 53
(chlamys) madisonius, iii, 292
newberryi, iii, 92
texanus, iii, 135
Pedinopsis pondi, iii, 189
Peet, C. E., cited, iii, 403
Pegmatite, i, 472
Pelagic deposits, i, 379-386
organic constituents of, i, 382
Pelagic fauna, i, 670
life of Devonian, ii, 479
Pelecypods, Carboniferous, ii,
615, 616
Chemung, ii, 478
Comanchean, iii, 134, 135, 136
Cretaceous, iii, 187, 190
Devonian, ii, 473, 477
Early Jurassic, iii, 91
Eocene, iii, 243
Genevieve, ii, 532, 533
Helderbergian, ii, 454
Jurassic, iii, 82, 83, 93
Kinderhook, ii, 520, 521
Middle Jurassic, iii, 91
Miocene, iii, 292, 295
Mississippian, ii, 525
Ordovician, ii, 354
Onondagan, ii, 466
Permian, ii, 653
shells of, i, 662
Silurian, ii, 403, 406
Triassic, iii, 53, 56
Upper Cambrian, ii, 299
Upper Jurassic, iii, 91, 92
Petee, i, 618
" Pele's hair," i, 404
Pelites, i, 472
Pelycosauria, ii, 649
Penck, E., cited, iii, 424
Peneplain, i, 81, 169
Penhallow, D. P., cited, ni, 490,
49i, 493
Pennington shale, ii, 503, 559,
560 ; iii, 549
Pennsylvania, Permian in, ii, 620
Pennsylvanian anthracite, ii, 577
fauna, ii, 616
Period, ii, 539
Pennsylvanian Period, duration
of, il, 583
System, sections of, ii, 557-
563
Penokee-Gogebic region, Animi-
kean of, ii, 188
Huronian of, ii, 180
Penrose, R. A. F., Jr., cited, i,
478; ii, 324, 337, 377; iii,
244, 261, 300, 560
Pensauken formation, iii, 449,
450
Pentacrinus briareus, iii, 84
Pentamerus, ii, 404
oblongus, ii, 404, 409, 458
Pentremital limestone, ii, 562;
iii, 560
Pentremites robisstus, ii, 532
Pentremitidea, ii, 470
Peorian interglacial formation,
iii, 494
Peorian interglacial stage, iii, 392
Peralkalic rocks, i, 458
Percalcic rocks, i, 458, 459
Perchaerus, iii, 253
Perfelic rocks, i, 456
Perfemane, i, 455
Perfemic rocks, i, 454
Perferrous rocks, i, 459
Peridotites, i, 416, 453
Periodicity of glaciation. iii, 433
Perisphinctes, iii, 91, 92
tiziani, iii, 81
Perissodactyls, Eocene, iii, 235
Miocene, iii, 284
Perlenic rocks, i, 456
Perlite, i, 408, 453, 472
Permian ammonites, ii, 653
amphibians, ii, 646
arthropods, ii, 652
Australia, ii, 632
brachiopods, ii, 653
cephalopods, ii. 653, 654
deformation, ii, 656
Europe, ii, 625
fishes, ii, 652
flora of America, ii, 642, 643
foreign, ii, 625
fresh- water life, ii, 652
gastropods, ii, 653
glacial beds of India, ii, 634
glacial beds of South Africa, ii,
635
glacial epoch, geographic fea-
tures of, ii, 675
glaciation of Australia, ii, 632
explanation of, ii, 674, 676
localization of, ii, 674
India, ii, 634
Kansas, section of, ii, 622
land animals of, ii, 646
life of, ii, 640
marine fauna, ii, 652, 654
pelecypods, ii, 654
Pennsylvania, ii, 620
Period, ii, 619
plant life of, ii, 642
problems of, ii, 655
relation of Triassic to, iii, 47
reptiles, ii, 647
INDEX.
611
Permian, South Africa, ii, 635
South America, ii, 638
system west of the Mississippi,
ii, 620
Texas, ii, 623
thickness of, ii, 625
Permiric rocks, i, 458
Permirlic rocks, i, 458
Fermitic rocks, i, 457
Pernopecten cooperensis, ii, 520
Perolic rocks, i, 457
Perpolic rocks, i, 456
Perpotassic rocks, i, 458
Perpyric rocks, i, 457
Perquaric rocks, i, 456
Perrey, A., cited, i, 537
Perrine, C. D., cited, i, 538
Perry, J. H., cited, ii, 549
Persalane, i, 455, 4~9
Persalic rocks, i, 454
Persodic rocks, i, 458
Pertilic rocks, i, 45?
Petalocrinus, ii, 411
mirabilis, ii, 403
Petrifaction, i, 223
" Petrified turtles," i, 496
Petroleum, i, 465
Miocene, iii, 279
Tertiary, iii, 280
Petrology, i, i, 393~485
Petrosilex, i, 472
Pfaff, F., cited, i, 537
Phacoides, iii, 295
(pseudomiltha) foremani, iii,
292
Phacops logani, ii, 455
rana, ii, 471
Phalen, W. C., cited, ii, 28
Phanerites, i, 451
Phanero-crystalline rocks, i, 412
Phenacodus, iii, 230
pnmaevus, iii, 230
Phenocrysts, i, 412
Philippines, Miocene of, iii, 281
Pliocene of, iii, 320
Phillips, J., cited, ii, 410
Phillipsia, ii, 618
major, ii, 616
Philosophic geology, i, i
Phinney, A. J., cited, ii, 336
Phlaocyon, iii, 253
Phlegethontia, ii, 608
Phobos, ii, 10
revolution of, ii, 63
Pholidogaster, ii, 538
Pholodomya, iii, 91
Phonolite, i, 472
Phosphates, Devonian, ii, 440
Florida, iii, 261
Ordovician, of Tennessee, ii,
337
Photobathic fauna, i, 670
life, ii, 292
zone, i, 670
Phragmoceras nestor, ii, 403
Phyllite, i, 472
Phyllocarids, Devonian, ii, 490
Phylloceras, iii, 134
knoxvillensis, iii, 136
Phyllograptus, ii, 364
Phyllograptus cambrensis, iia 287
ilicifolius, ii, 362
typus, ii, 362
Phyllopods, Devonian, ii, 490
Phylloporina granistriata, ii, 358
Phyllotheca, ii, 646
indica, ii, 645
Physa prisca, ii, 528
Physiographic geology, i, i
Physiography, Newark Series,
iii, 19
Phytosauria, iii, 42
Picayune andesite, iii, 572
Pickens sandstone, iii, 548
Picrolite, i, 465
Pictotite, i, 465
Piedmont glacier, i, 254
Piedmont plain, alluvial, 5, 183
Piedmontite, i, 465
Pierre shale, iii, 151, 153, 154,
155, 206, 564, 566, 570
Pilot Rock, iii, 340
Pinal schist, iii, 575
Pinna, iii, 91
Pinyon conglomerate, iii, 210
Piracy, i, 160
domestic, i, 104
extent of, in Appalachians, i,
170
foreign, i, 104
of Kaaterskill Creek, i, 105
of Plaaterskill Creek, i, 105
Pirsson, L. V., cited, i, 412, 451,
573; (and Weed), iii, 120
Pismo formation, iii, 264, 310,
577
Pisolite, i, 465, 496
Pitchstones, i, 408, 453, 472
Pithecanthropus erectus, iii, 325,
326
Pitted plains, iii, 373
Pittsford shale, ii, 390
Plaatekill Creek, piracy of, i,
105
Placentals, Eocene, iii, 228
Pliocene, iii, 322
possible origin in Africa, iii,
224
Placodontia, ii, 339
Plagioclase, i, 465
Plain, alluvial, i, 181, 184
graded, i, 169
outwash, i, 306
Plainfield, N. J., terminal mo-
raine near, iii, 364
Planation, i, 82
glacial, iii, 346
Planetary nuclei, ii, 61
growth of, ii, 64, 67, 78
Planetary orbits, shifting of, ii, 78
rings and rotation, ii, 70
rings, formation of, ii, 4
rotation, ii, 70-75
rotation, on accretion hypoth-
esis, ii, 70
rotation, on Laplacian hypoth-
esis, ii, 70
Planetesimal collisions, ii, 66, 72
condition, from gaseous spher-
oid, ii, 39
Planetesimal condition, from
meteorites, ii, 40
from original nebular disper-
sion, ii, 40
Planetesimal hypothesis, def-
ormations under, ii, 122
early stages of earth under,
ii, 91
sub-varieties of, ii, 38
Planetesimal infall, effect on
temperature, ii, 68
motions, ii, 64
nebulae, ii, 48
orbits elliptical, ii, 72
Planets, eccentricities of, ii,
79
origin of, ii, 60
spacing out of, ii, 78
Planorbulina, iii, 294
Plant-growth, influence of car-
bon dioxide on, ii, 605
Plant kingdom, geologic con-
tributions of, i, 652-658
Plant life and carbon dioxide, i,
665
Plant life, Cambrian, ii, 278
Carboniferous, ii, 591
Cretaceous, iii, 173
Devonian, ii, 491
Jurassic, iii, 94
Mississippian, ii, 537
Ordovician, ii, 346
Pennsylvanian, ii, 591
Permian, ii, 642
Silurian, ii, 409
Triassic, iii, 38
Plant societies, i, 667
Plants, contribution to deposits,
i, 652-658
effect on erosion, i, 131, 644
migration, in glaciated areas,
«i. 533
reference table of, i, 653
weathering influenced by, i,
112
Platanus, iii, 173
Plateaus, origin of, ii, 124
Platecarpus coryphaeus, iii, 180
Platephemera antiqua, ii, 494
Platte river, i, 187
Platyceras dumosum, ii, 462
gibbosum, ii, 455
nodosus, ii, 459
primaevum, ii, 297
spirale, ii, 455
Platycrinus, ii, 522
gorbyi, ii, 525
verrucosus, ii, 525
Platygonus compressus, iii, 230
Platyostoma broadheadi, ii, 524
Platysomus, ii, 652
gibbosus, ii, 653
Platystrophia biforata, ii, 367
lynx, ii, 356
Playas, iii, 458
Pleasonton shales, ii, 561
Plectambonites sericeus, ii, 356,
367
Plectorthis newtonensis, ii, 299
Pleistocene armadillo, iii, 498
612
INDEX.
Pleistocene bison, iii, 491
buffaloes, iii, 498
deformation, iii, 480, 518
diastrophism in Lake Bonne-
ville, iii, 461
elephant, iii, 496
faunas iii, 494
fossils, mixing of, iii, 488
glaciation, localization of, iii,
433
glaciation, periodicity of, iii,
433
horses, iii, 498
life, Alpine remnants, iii,
489
life, European, iii, 498
mammals, iii, 496-498
mammoth, iii, 491, 496
man, iii, 502
man, in Europe, iii, 513
mastodon, iii, 491, 496
musk-ox, iii, 498
Pleistocene Period, iii, 327
changes of level during, iii,
480
climatic adaptations of life in,
iii, 486
close of, iii, 517
diastrophism during, iii, 480,
Si8
igneous eruptions in Lake
Bonneville during, iii, 459
human relics, iii, 502
land life, iii, 495
life, iii, 483
Africa, iii, 501
Australia, iii, 501
South America, iii, 500
Southern Hemisphere, iii, 500
marine life, iii, 494
migration of climatic zones,
iii, 486
migration of life, iii, 485
superposition of cold and
warm faunas, iii, 487
Pleistocene, South American
mammals, iii, 498
spring deposits, iii, 446
Pleistocene system, Coastal Plain,
iii, 447
Columbia formation, iii, 447
eolian deposits, iii, 446,
454
eolian deposits in west, iii,
474
fluviatile deposits, iii, 446
igneous rocks, iii, 447. 477
lacustrine deposits, iii, 446,
453
map of, iii, 332
marine deposits, iii, 447. 476
non-glacial deposits, iii, 446
non-glacial deposits of in-
terior, iii, 454
terrestrial organic deposits, iii,
446
West, iii, 455
Plesiosauria, iii, 42
Cretaceous, iii, 180
Jurassic, iii, 88
Plesiosauria, Triassic, iii, 45
Plesiosaurus dolichodeirus, iii,
89
Pleurocystis filitextus, ii, 359
Pleurodira, iii, 44
Pleuromya, iii, 91
unioides, iii, 93
Pleurotoma potomacensis, iii,
243
tysoni, iii, 243
Pleurotomaria nodulostriata, ii,
532
Pliauchenia, iii, 286
Plicatella, iii, 91
Pliocene ant-eaters, iii, 321
armadillos, iii, 321
carnivores, iii, 322, 323
deer, iii, 322
elephants, iii, 323
giraffes, iii, 323
herbivores, iii, 322, 323
hippopotamuses, iii, 323
horses, iii, 322
land animals, iii, 321
land plants, iii, 320
llamas, iii, 322
mastodons, iii, 322, 323
monkeys, iii, 322
Pliocene Period, iii, 296
faulting during, iii, 313
life, iii, 320
marine life, iii, 326
erogenic movements, iii, 311,
316
vulcanism, iii, 315, 317
Pliocene placentals, iii 322
primates, iii, 323
proboscidians, iii, 323
rhinoceroses, iii, 323
rodents, iii, 322, 323
sloths, iii, 321, 322
Pliocene system, aggradation
deposits, iii, 296
Arizona, iii, 310
Atlantic coast, iii, 308
Borneo, iii, 320
British Columbia, iii, 315
California, iii, 310
Egypt, iii, 320
Europe, iii, 318
foreign, iii, 318
Gay Head, iii, 308
Gulf coast, iii, 309
gypsum of, iii, 318
map of, iii, 297
marine beds, iii, 308
Mayence basin, iii, 319
naphtha, iii, 318
Pacific coast, iii, 3<>9
Philippines, iii, 320
salt, iii, 318
Tibet, iii, 320
Vienna basin, iii, 319
Pliocene tapirs, iii, 322, 323
tigers, iii, 323
Pliohippus, iii, 286
Plugs, volcanic, i, 59*
Plumbago, i, 465
Plunging anticline, i, 155
Plutonic rocks, i, 472
Po river, delta of, i, 202
sediment carried by, i, 107
Pocahontas formation, ii, 559
Pocono sandstone, ii, 500, 502,
557,558; iii, 548
Podocarpus, iii, 173
Podozamites, iii, 39, 173
tenuistriatus, iii, 41
Poebrotherium, iii, 253
Pogonip limestone, iii, 576
Pohlman, J., cited, iii, 415
Poincare, H., cited, i, 576
Point of Rocks formation, iii, 313
Poison Canyon formation, iii,
153, 206, 207
Pokegama quartzite, ii, 189
Polandian epoch, iii, 421
Polar glaciers, i, 254
Pole, wandering of, and glacial
climate, iii, 431
Polic rocks, i, 456
Polk Bayou limestone, iii, 561
Polmitic rocks, i, 457
Polygyra clausa, iii, 410
monodon, iii, 410
multilineata, iii, 410
Polymorphina, iii, 294
Polynices (Neverita) duplicatus,
iii, 294
Polypora lilaea, ii, 455
Polystomella, iii, 294
Ponderosa formation, iii, 142
Ponding of streams, i, 171
Popanoceras, ii, 655
walcotti, ii, 654
Porcellia nodosa, ii, 520
Porphyries, i, 453
Porphyrite, i, 472
Porphyritic rocks, i, 411
Porphyry, i, 472
Portage formation, ii, 432
Posepny, F., cited, i, 474
Post-Cambrian and pre-Cam-
brian evolution, ii, 293
Post-glacial time, duration, iii,
415
Post-Permian deformation, se-
quences of, ii, 658, 660
Post-Pliocene elevation and cli-
mate, iii, 316
Pot-holes, i, 140
Potash, in sea-water, i, 377
Potassium salts in Pennsyl-
vania, ii, 630
Potean beds, ii, 562; iii, 560
Poterioceras apertum, ii, 352
Potomac river, i, 168
sediment carried by, i, 107
Potomac series, iii, 111,112, 113,
449
stratigraphic relations, iii, 114
thickness, iii, 115
Potonie, H., cited, i, 652; ii,
595; iii, 41
Potosi series, iii, 572
Potsdam sandstone, ii, 219, 225;
iii, 557
Pottsville conglomerate, ii, 539t
542, 557, 558, 560; iii,
554
INDEX.
613
Powell, J.W., cited, i.SiQ, 521 ; ii,
i53f 210; iii, 208, 209, 314
Pre-Cambrian and Post-Cam-
brian evolution, ii, 293
Precipitation, i, 50
from atmosphere, i, 51
from solution, 1,41,225,239,
375-379
from solution, conditions in-
fluencing, i, 225
from solution, influenced by
algae, i, 225
Predentata, iii, 97
Present Period, iii, 517
Pressures within earth, based on
Laplace's law, i, 564
Preston, cited, iii, 437
Prestwich, J., cited, i, 203, 225;
i", 5i5
Prestwichia danae, ii, 611,
613
Priacodon ferox, iii, 105
Prima, iii, 91
Primates, Eocene, iii, 239
Miocene, iii, 289
Pliocene, iii, 323
Primitive gneiss, ii, 142
Princeton conglomerate, ii, 559
Prionotropis woolgari, iii, 189
Priscodelphinus, iii, 294
Proboscidians, Miocene, iii, 284
Pliocene, iii, 323
Procamelus, iii, 286
Prodromites gorbyi, ii, 520
Productella, ii, 465, 478
Mississippian, ii, 528
pyxidata, ii, 520
spinulicosta, ii, 462
Productids, ii, 465
Hamilton, ii, 472
Productive beds, iii, 560
Productus, ii, 465, 615
arcuatus, ii, 520
burlingtonensis, ii, 525
cora, ii, 617
costatus, 616, 617
fasciculatus, ii, 532
Genevieve, ii, 531
marginicinctus, ii, 532
Mississippian, ii, 528
nebrascensis, ii, 616, 617
semireticulatus, ii, 617, 653
symmetricus, ii, 616, 617
Proetus ellipticus, ii, 520
Proganochelys, iii, 44
Proganosauria, ii, 649
Prognostic geology, iii, 542
Progonoblattina columbiana, ii,
611
parviusculus, ii, 349
Proptychites, iii, 52
Propylite, i, 472
Prospect Mountain limestone, iii,
576
quartzite, Hi, 576-"
Prosser, C. S., cited, 'i, 250, 318,
420, 434, 500, 502, 511,
540,542, 546, 558, 560,
619, 621, 622, 653; iii,
25, 118,554
Protapirus, iii, 253
Proterohippus, iii, 235
Proterosauria, ii, 648; iii, 42
Permian, ii, 649
Proterozoic, Adirondack region,
ii, 205
Cordilleran region, ii, 210
duration of, ii, 198
eastern provinces of Canada,
ii, 204
Eastern United States, ii, 211
era, ii, 162
climate of, ii, 217
exposures of, u, 202
extra-American, ii, 215
great northern area, ii, 203
Green Mountains, ii, 213
Lake Superior region, ii,
175
life, ii, 216
map of, ii, 147
Marquette region, N. Mich., ii,
174, 176
Minnesota, ii, 173, 174
New Jersey, ii, 213
original Laurentian area, ii,
204
outside Lake Superior region,
ii, 202
relations to Archean, ii, 139,
171
rocks, Black Hills, ii, 174
rocks, contrasted with Archeo-
zoic, ii, 139
Rocky mountains, ii, 174
sedimentation, ii, 166
sediments, extent of, ii, 168
South Dakota, ii, 173
southeastern Missouri, ii, 209
stratigraphic relations of, ii,
163
subdivisions of, ii, 165
succession, Lake Superior re-
gion, ii, 200
system, rocks of, ii, 169
Wyoming, u, 210
Protobalanus hamiltonensis, ii,
47i
Protocardia, iii, 134
levis, iii, 243
Protocaris marshi, ii, 283
Protoceras, Eocene, iii, 253
Miocene, iii, 284
Protogine, i, 472
Protohippus, iii, 286
Protolabis, iii, 286
Protomeryx, iii, 253
Protopterus, ii, 487
Protorhyncha antiquata, ii,
285
Protorosauria, iii, 647
Protorthis billingsi, ii, 298, 299
Protostega, iii, 180
Protowarthia cancellata, ii, 353
Protozoa, Cambrian, ii, 287
Carboniferous, ii, 616, 618
Devonian, ii, 467
Genevieve, ii, 531, 532
geologc contribution of, i,
660
Protozoa, Ordovician, ii, 361
Protremata, ii, 356
Provinces, general, of Triassic
system, iii, 38
Provincial development of Ordo-
vician life, ii, 343
faunas, i, 668
Provincialism, human, iii, 540
Proviverra, iii, 237
Psammochelys, iii, 44
Psaronius, Devonian, ii, 493
Pseudomiltha, iii, 292
Pseudomonotis curta, iii, 93
Pseudomorphs, i, 465
Pseudopecopteris, Mississippian,
ii, 537
Psilomelane, i, 465
Psilophyton, ii, 494
Psychological factors, i, 651
Pteranodon, iii, 179
Pteraspis, ii, 484, 485
Pteridophytes, ii, 592
Devonian, ii, 492, 493
geologic contribution of, i, 657
Triassic, iii, 38
Pteridospermae, Devonian, ii, 493
Pennsylvanian, ii, 595
Pterinea demissa, ii, 354
emacerata, ii, 403
flabella, ii, 471
Pterodactyls, Jurassic, iii, 102
Pterodactylus, iii, 101
spectabilis, iii, 103
Pteroperna, iii, 91
Pterophyllum, iii, 39
Pteropod ooze, i, 380, 382
Pteropods, Cambrian, ii, 298
Chemung, ii, 478
Devonian, ii, 473
Mississippian, ii, 523
Silurian, ii, 407
Pterosauria, iii, 42, 43
Cretaceous, iii, 179
Jurassic, iii, 101
Pterotocrmus bifurcatus, ii, 532
Pterygometopus calhcephalus, ii»
349
Pterygotus, ii, 412
Devonian, ii, 490
Ptilophyllum, iii, 95
Ptilophyton, ii, 4P4
Ptychoceras crassum, iii, 189
Ptychoparia, u, 299
antiqua, ii, 299
kingi, ii, 298, 299
Ptychosalpinx, iii, 295
Puerco formation, iii, 207
Puget formation, iii, 202, 203
Pugh formation, iii, 548
Pugnax uta, ii, 616, 617
Pulaski formation, iii, 202
shale, ii, 559
" Pulpit rocks," i, 350
Pumice, i, 406, 453, 472
Pumpelly, R., cited, ii, 198; iii,
411
Pupa vermilionensis, ii, 611
Purbeck beds, iii, 76
Purington, C. W.v cited, iii, 69,
207. 209
614
INDEX.
Purpura, iii, 294
Push moraine, i, 301
Putnam, G. R., (and Gilbert,)
cited, ii, 236
Putorius, iii, 289
Puzzalana, i, 405
Pyrazus, iii, 295
Pyrite, i, 465
Pyroclastic rocks, i, 404, 406, 472
Pyrolic rocks, i, 457
Pyropsis bairdi, iii, 189
Pyroxene, i, 400, 465
Pyroxenite, i, 41?, 452, 472
Pyrula, iii, 295
Pythonomorphs, iii, 185
Cretaceous, iii, 180
Triassic, iii, 43
Quadrant formation, iii, 70, 157,
166, 568
quartzite, ii, 153
Quadrumana, iii, 229, 239
Quaquaversal dip, i, 504
Quardofelic rocks, i, 456
Quarfelic rocks, i, 456
Quartz, i, 466
Quartzite, i, 447, 472
Quartz-leucophyres, i, 453
Quartzophyres, i, 453
Quartz-porphyries, i, 453
Quaternary (see Pleistocene)
Queen Charlotte series, iii, 123
Queensland, coal in Jurassic of,
iii, 78
Quenstedioceras, iii, 92
Quercophyllum, iii, 133
Quercus, iii, 173
suspscta, iii, 174
Quinnimont shale, ii, 559
Quinnisec series, ii, 142, 160
Radioactive matter, luminescent
properties of, ii, 59
Radioactive substances, ii, 52
Radiolarian ooze, i, 380, 382,
425, 661
Radiolarians, Jurassic, iii, 85
Rafinesquina alternata, ii, 356
Rain, amount of, i, 51
erosion by, i, 57
mechanical work of, i, 51
Rain-drop impressions, i 490
Rainfall, effect on erosion, i, 128
Raleigh sandstone, ii, 559
Ramsay, A. C., cited, ii, 588, 627
Rancocas formation, iii, 140
Randall, F. A., cited, iii, 382
Randville dolomite, ii, i79» 180
Ranella, iii, 295
Rangia, iii, 295
Ransome, F. L., cited, i, 130,
513; ii, 430; iii, 118, 124,
210
Raphistomina lapicida, ii, 353
Rapids, development of, i, 133,
146
Raritan clays, iii, 113, 114
Rate of erosion, conditions
affecting, i, 123
Rattlesnake beds, iii, 299
Ravine, i, 64
Raymond, R. W., cited, i, 474
Rays, Miocene, iii, 294
Reade, T. M., cited, i, 225, 366,
56i, 572
Reagan, A. B., cited, ii, 390;
iii, 299
Receptaculites occidentals, ii,
363
Silurian, ii, 408
Recessional moraine, iii, 367
Reconstructed glacier, i, 256
Red Beds, ii, 621, 624; iii, 25,
26, 27, 63, 70, 565
Red clay, i, 380, 383, 384
Red mud, i, 380
Red River of Louisiana, i, 188
Red Wall formation, iii, 313,
574
Redlich, K. A., cited, ii, 272
Reef-building corals, ii, 463
Re-forestation of glaciated areas,
iii, 530
Regan sandstone, iii, 563
Regolith, i, 400, 472
Reid, H. F., cited, i, 256, 259, 261
Reinechia, iii, 92
brancoi, iii, 81
Rejects, iii, 504
Rejuvenation of streams, i, 162,
163
criteria of, i, 164, 165, 166
Relief, of lithosphere, i, ii
of ocean basins, i, ii
representation on maps, i, 30
Relief of pressure, a cause of
volcanic action, i, 627
Renault, B., cited, ii, 493, 591
Rendu, L. C., cited, i, 321, 322
Rensselaeria, ii, 456, 459
aequiradiata, ii, 455
ovoides, ii, 458
Re-peopling of glaciated areas,
iii, 530
Reptiles, Eocene, iii, 240
flying, Jurassic, iii, 101
marine, Jurassic, iii, 86
marine, Triassic, iii, 45
Miocene, iii, 290
Permian, ii, 647
Restrictive evolution, i, 672
Reteograptus eucharis, ii, 362
Reticularia pseudolineata, ii, 525
Retrograde rotation, ii, 70
Retusa (cylichnina) conulus, iii,
294
Reusch, H., cited, ii, 159, 272
Reversed fault, i, 517, 521
Reyer, E., cited, i, 636
Reynosa limestone, iii, 300
Rhacophyllites, iii, 91
Rhaetic formation, iii, 34
Rhamphorynchus, iii, 101
phyllurus, iii, 101, 102
Rhine river, material in solution
in, i, 108
Rhinobatidae, iii, 85
Rhinoceroses, Miocene, iii, 289
Oligocene, iii, 254
Pliocene, iii, 323
Rhipidomella burlingtonensis, ii,
525
oblata, ii, 455
pecosi, ii, 616, 617
vanuxemi, ii, 471
Rhizodus, ii, 614
Rhizopods, Cretaceous, iii, 186
geologic contributions of, i
660
Rhone basin, Pliocene of, iii, 319
Rhone river, delta of, i, 203
material in solution in, i, 108
sediment carried by, i, 107
Rhynchocephalia, iii, 42, 185
Cretaceous, iii? 181
Jurassic, iii, 100
Rhynchonella, ii, 472; iii, 57,
91,92, 134
aequiplicata, iii, 53
Rhynchonella eurekensis, ii, 530,
532
gnathophora, iii, 93
Rhyncotrema capax, ii, 356
cuneata, ii, 403, 409
Rhyolite, i, 472
Rhyolitic structure of lavas, i,
Rhytimya radiata, ii, 354
Ricard, T. A., cited, i, 474
Richardson, G. B., cited, ii, 308,
582
Richmond beds, ii, 319; iii, 555
coal-beds, iii, 40
earth, iii, 260
Richmondville sandstone, iii, 553
Richthofen, F. von, cited, i, 23,
604, 614, 615; ii, 159, 272,
300, 590
Rico formation, iii, 572
Ries, H., cited, iii, 113; (and
Merrill), 403
Rift valleys, ii, 131
Riggs, E. S., cited, iii, 99
Rigi beds, iii, 276
Rigidity, distribution of, i, 578
Rill-marks, i, 372, 489
Ring of Saturn, origin of, ii, 63
revolution of, ii, 63
Rink, H., cited, i, 248
Ripley fauna, iii, 187
formation, iii, 141, 142
Ripple-marks, i, 371, 489
due to wind, i, 37
Rio Grande river, sediment of, i,
107
Rise of lava, ii, 103
arrest of, ii, 104
Ritchey, G. W., cited, ii, 44, 45»
46, 49
River erosion (see Stream ero-
sion)
River lakes, i, 198
Roanoke river, i, 168
Roche, E., cited, ii, 22, 24
Roche limit, ii, 34
Roches moutonnees, i, 304! "i»
35i
Rochester shale, ii, 370, 377
Rock-breaking, by changes of
temperature, i, 44, 49
INDEX.
615
Rock terraces, i, 140, 204
Rock waste, i, 12
Rockcastle conglomerate lentil,
ii, 560
Rockford limestone, iii, 556
Rocks, alferric, i, 454
alkalicalcic, i, 458
alkalimirlic, i, 458
alterations of, i, 426
aqueous, i, 467
arenaceous, i, 468
autoclastic, i, 444
calcimiric, i, 458
" chimney," i, 350
chloritic, i, 431
classification and nomencla-
ture, i, 449
clastic, i, 468
crystalline, i, 16
determination of age, i, 15
disruption by hydratlon, i, in
docalcic, i, 458
dofemic, i, 454
doferrous, i, 459
dohemic, i, 457
dolenic, i, 456
domagnesic, i, 459
domalkalic, i, 458
domilic, i, 457
domiric, i, 458
domirlic, i, 458
domitic, i, 457
dopolic, i, 456
dopotassic, i, 458
dopyric, i, 457
doquaric, i, 456
dosalic, i, 454
dosodic, i, 458
dotilic, i, 457
eolian, i, 469
femic, i, 454
glassy, i, 406
holocrystalline, i, 412
hypogene, i, 470
igneous, i, 16, 393, 498
leading elements of, i, 396
lendofelic, i, 456
lenfelic, i, 456
magnesiferrous, i, 459
meta-igneous, i, 471
metamorphic, i, 16
mirlic, i, 458
mitic, i, 456
organic, i, 646
origin and descent of, i, 393-
485
peralkalic, i, 458
percalcic, i, 458, 459
perfelic, i, 456
perfemic, i, 454
perferrous, i, 459
perhemic, i, 457
perlenic, i, 456
permagnesic, i, 459
permerlic, i, 458
permiric, i, 458
permitic, i, 457
perolic, i, 45?
perpolic, i, 456
perpotassic, i, 458
Rocks, perpyric, i, 457
perquaric, i, 456
persalic, i, 454
persodic, i, 458
pertilic, i, 457
phanerocrystalline, i, 412
plutonic, i, 472
polic, i, 456
polmitic, i, 457
porphyritic, i, 411
precipitate, i, 427
" pulpit," i, 350
pyroclastic, i, 404, 406, 472
quardofelic, i, 456
quarfelic, i, 456
salfemic, i, 454
salic, i, 454
secondary, i, 420
sedimentary, i, 422, 486
sodipotassic, i, 458
solution of, i, 427
specific heat of, i, 552
stratified, i, 14
talcose, i, 431
tilhemic, i, 457
Rockwood formation, iii, 548,
55i
Rodentia, iii, 229
Eocene, iii, 238
Miocene, iii, 284
Pliocene, iii, 322, 323
Rogers, A. W., cited, ii, 635
Rogersville shale, iii, 550
Rome formation, iii, 550
Rominger, C., cited, ii, 280
Romney shale, iii, 548
Rondout waterlime, ii, 370
Roots, wedgework of,i, 112, 131,
ISO
Roslyn formation, iii, 210, 211,
578
Rotalia, iii, 294
Rotary motion, origin of, ii, 56
Rotation of earth, change in
rate of, i, 575
effect on stream erosion, i, 194
Rotation and vulcanism, i, 604
Roth, J., cited, i, 108
Rothliegende, ii, 626
Rotten limestone, iii, 141
Rove slate, ii, 190
Rowe schist, iii, 546
Rubens, cited, ii, 631; (and
Ashkinass), iii, 444
Ruby formation, iii, 156, 157,
570
Rudistae, iii, 134
Ruminants, Miocene, iii, 285
Running water (see Streams)
Run-off, i, 59
Russell, I. C., cited, i, 108, 118,
151, 172, 194, 203, 232, 256,
283,388,392,636; iii, 2,9,
14, 311, 362, 370, 411, 463,
464, 465, 467, 477, 478, 479 ;
(and Johnson), 462
Russia, Cretaceous, Lower, iii,
129
Cretaceous, Upper, iii, 168
Devonian of, ii, 447
Russia, Jurassic of, iii, 71
Mississippian of, ii, 512,
Oligocene of, iii, 249
Ordovic':an of, ii, 339
Pennsylvanian of, ii, 587
Permian of, ii, 628
Proterozoic of, ii, 215
Triassic of, iii, 34
Rutile, i, 466
Saber-toothed tiger, Pliocene iii,
323
Pleistocene, iii, 498
Saccharoidal sandstone, iii, 561
Safford, J. M., cited, iii, 141, 301
411
Saginaw series, iii, 553
St. Anthony Falls, i, 136
age of, iii, 415
St. Clair shales, iii, 553, 560
St. Croix sandstone, ii, 219; iii,
559
St. Genevieve series, ii, 500
limestone, ii, 561
St. John, O. H., cited, ii, 534
St. Lawrence embayment, ii, 450,
468
St. Louis fauna, ii, 529
formation, ii, 500, 502, 561;
i", 552, 558
St. Peters sandstone, ii, 313,
320; iii, 557,559
Saint Vincent, i, 605
Salamanders > Cretaceous, iii, 7<>
Salenia tumidula, iii, 189
Salfemane, i, 455
Salfemic rocks, i, 454
Saliciphyllum, iii, 133
Salina beds, ii, 370
epoch, aridity of, ii, 388
Saline lakes (see Salt lakes)
springs, i, 235
Salisbury, R. D., cited, i, 203-,
256; iii, 148, 334, 361, 368,
370, 371, 384, 403, 475, 5i6;
(and Call), iii, 302; (and
Chamberlin), iii, 344, 411
Salt, Mississippian, ii, 500
occurrence of, ii, 517, 518
Permian, ii, 628
Pliocene, iii, 318
Salina series, ii, 387
Siberia, ii, 342
Trias, iii, 25, 29, 34, 35
Salt lakes, i, 391
composition of, i, 372
deposits in, i, 388
Salter, J. W., cited, ii, 280
Salts, deposition of, i, 375-378
in Great Salt Lake, iii, 458
in sea- water, i, 324-326
of Stassfurt, ii, 630
Salt-wells formation, iii, 313
Saluda beds, iii, 555
Samotherium, iii, 323
San Diego formation, iii, 310
San Juan formation, iii, 209, 572
San Luis formation, iii, 68, 264,
577
San Miguel formation, iii, 69, 207
616
INDEX.
Sand, eolian, i, 26-37
Sandstone, i, 422, 434, 472
crushing strength of, ii, 127
stratification of, i, 487
Sandstone dikes, i, 514
Sandsuck shale, iii, 550
Sangamon interglacial forma-
tion, iii , 494
Sangamon interglacial stage, iii,
39i
Sanidine, i, 466
Santa Cruz beds, iii, 281
Santa Cruz mountains, Pliocene
movement in, iii, 316
Santa Margarita formation, iii,
3io, 577
Santee formation, iii, 199
Saportea, ii, 643
salisburioides, ii, 643
Sapping, i, 127, 133
Saratogan series, ii, 219
Sardeson, F. W., cited, ii, 302,
357
Sarle, C. J., cited, ii, 376
Sassafras, iii, 132, 133, 173
subintegrifolium, iii, 174
Satellites of Neptune, ii, 71
of Uranus, revolution of, ii, 71
Satinspar, i, 466
Sauropoda, iii, 97
Sauropterygia, ii, 649; iii, 42
Triassic, iii, 45
Saurians, Cretaceous, iii, 180
marine, Cretaceous, iii, 180
Sauropus, Mississippian, ii, 537
Savannah sandstone, iii, 562
Savoy schist, iii, 546
Sa watch quartzite, ii, 154; iii,
57i
Saxicava, iii, 295
jurassica, iii, 92
sands, iii, 494
Saxonian epoch, iii, 421
Scala potomacensis, iii, 243
sayana, iii, 294
Scandinavia, Ordovician, ii, 338
Triassic coal-beds of, iii, 41
Scanian epoch, iii, 421
Scapharca, iii, 292, 295
Scaphslla, iii, 294
Scaphites nodosus, iii, 189
Scaphopod, Miocene, iii, 294
Scarboro formation, iii, 491
Schist, i, 446, 472
series of Archean, ii, 142
Schistoslty, i, 443
Schizocrania filosa, ii, 356
Schizoius chesterensis, ii, 533
wheeleri, ii, 616
Schizolepis liaso-keuperinus, iii,
4i
Schizolopha textilis, ii, 353
Schizoneura, ii, 646
gondwanensis, ii, 645
Schizophoria multistriata, ii, 455
striatula, ii, 475, 476
swallovi, ii, 525
Schizotreta fissus, ii, 356
ovalis, ii, 356
Schlaenbachia, iii, 134
Schloesing, cited, ii, 666
Schmidt, J. F. J., cited, i, 537
bchoharie Creek, i, 105
Schoharie grit, ii, 424
Schrader, F. C., cited, ii, 436;
iii, 124, 125, 161, 248, 299;
(and Mendenhall), iii, 124
Schuchert, C., cited, ii, 221, 225,
ii, 391, 458; (and Clarke),
ii, 31°, 370, 420; (and Ul-
rich), 250, 312, 32 1, 344, 41 1,
427, 432; (and White), iii,
124, 132
Schwarz, E. H. L., ii, 273-448,
636
Sciurus, iii, 253
Scoriae, i, 405, 473
Scorpions, Carboniferous, ii, 611
Devonian, ii, 490, 495
first appearance of, ii, 415
Scotland, overthrust in, ii, 341
Scott, E. H., cited, ii, 493, 505,
596, 601 ; iii, 39
Scott, W. B., cited, ii, 294; iii,
119, 223, 228, 255, 269
Scott shale, iii, 549
Scour-and-fill, i, 194
of Missouri river, i, 195
Scrope, G. P., cited, i, 636
Scudder, S. H., cited, ii, 494, 610
Scutella, iii, 294
Sea, the (see Ocean)
Sea-caves, i, 350
Sea-cliffs, i, 349
Sea-urchins, Cretaceous, iii, 186
Jurassic, iii, 84
Sea-water, aperiodic movements
of, i, 338
movements, i, 334-342
movements generated by at-
traction, i, 337
salts in, i, 376, 377, 378
Sea-waves, caused by earth-
quake, i, 535
Secondary rocks, derivation of, i,
420
" Second bottoms," i, 205
Secret Canyon shale, iii, 576
Secretions, i, 497
Section of strata, in Alabama,
iii, 55i
Arizona, iii, 575
Arkansas, iii, 560
Black Hills, iii, 566
California, iii, 577
Colorado, iii, 570, 572
Eureka District, Nevada, iii,
576
Grand Canyon region, iii, 574
Indian Territory, iii, 562
Indiana, iii, 556
Iowa, iii, 558
Massachusetts, iii, 546
Michigan, iii, 553
Montana, iii, 568
Nebraska, iii, 564
Ohio, iii, 554, 555
Tennessee, iii, 549, 550, 552
Virginia, iii, 548
Washington, iii, 578
Section of strata, in West Vir-
ginia, iii, 548
Wyoming, iii, 565
Sections of the Huronian, ii,
179
of Ordovician in interior, ii,
319
Secular changes of temperature,
and CO2 of ocean, ii, 668
Sederholm, J. J., cited, ii, 159,
215
Sediment, of the Danube, i, 107
of the Irrawaddy, i, 107
of the Mississippi, i, 107
of the Nile, i, 107
of the Po, i, 107
of the Potomac, i, 107
of the Rhone, i, 107
of the Rio Grande, i, 107
of the Uruguay, i, 107
character of, influenced by
land vegetation, i, 645
deposited by rivers, i, 65, 177-
204
deposited in lakes, i, 387
deposited in sea, i, 368-386
effect on falls, i, 137
how carried by streams, i, 116
Sedimentary eon, ii, 91
Sedimentary rocks, classes of, i,
422
structural features of, i, 486
Sedimentation, Cambrian, ii,
246
Ordovician, ii, 304
Sedimentation and continental
creep, ii, 132
Sedimentation and vulcanism, i,
629
Seed-plants, i, 657
Seeley, H. G., cited, iii, 170
Seeley, H. M., (and Brainard,)
cited, ii, 364
Segregation of ores, i, 475
Seiches, i, 386
Seine river, intrenched mean-
ders of, i, 164
Selective fusion, ii, 102
Selenite, i, 466
Selma chalk, iii, 141, 142
Seminole conglomerate, iii, 562
Seminula, ii, 531
argentea, ii, 616, 617
subquadrata, ii, 532
Semnopithecus, iii, 325
maurus, iii, 326
Senecan series, ii, 432
Senora formation, iii, 562
Septa, iii, 295
Septaria, i, 473, 495
Septastrea, iii, 294
Sequoias, Cretaceous, iii, 173
Serpentine, i, 431, 466, 473
Serpentine kames, i, 306
Sevier shale, ii, 316; iii, 549
Sewell formation, ii, 559
Seward, A. C., cited, i, 652; ii,
598
Shakopee limestone, iii, 559
Shale, i, 422, 434, 473
INDEX.
617
Shaler, N. S., cited, i, 227, 349,
357; (and Davis), 256; ii,
544, 549; iii, 370; (and
Woodworth), 8, 10, 15, 17,
18
Shallow-water deposits, i, 368,
369, 379
characteristics of, i, 373
topography of, i, 374
Shark River marl, iii, 198
Sharks, Devonian, ii, 461, 469,
489
Miocene, iii, 294
Mississippian, ii, 535
Sharon conglomerate, ii, 557
Shastan system, iii, 107, 108, 122
Shaw, J., cited, iii, 370, 411
Shawangunk grit, ii, 370, 372
mountains, ii, 371
Shear zone, subcrustal, ii, 126
Shearing of glacier ice, i, 317
Sheet erosion, i, 59
Shell marl, i, 655
Shenandoah limestone, iii, 548
Shepard, E. M., cited, ii, 424
Sherzer, W. H., cited, ii, 424
Shimek, B., cited, iii, 409, 411,
412
Shinarump formation, iii, 313
Shore currents, i, 342
deposition by, i, 355
Shore deposition and coastal con-
figuration i, 363
Shore drift, i, 355
Shore ice, i, 389
Shoshone Falls, i, 135
Shumard, B. F., cited, ii, 561
Siamo slate, ii, 150, 179
Siberia, Ordovician of, ii, 342
Siderite, i, 425, 466
Siebenthal, C. E., cited, ii, 54
Sierran Period, iii, 311
Sigillaria, Carboniferous, ii, 598,
599, 603
Devonian, ii, 493
Mississippian, ii, 537
Permian, ii, 642
Triassic, iii, 39
Silicified wood, i, 439
Siliceous deposits, i, 425
Sills, i, 446, 592
Silurian blastoids, ii, 400, 403
brachiopods, ii, 401, 403
bryozoans, ii, 405, 406
cephalopods, ii, 403, 405
ceratiocarids, ii, 408
chain coral, ii, 407
climate, ii, 396
close of, ii, 395
coral development, ii, 407
coral reefs, ii, 407
corals, ii, 406
crinoids, ii, 400, 403
crustaceans, ii, 408
cystoids, ii, 4orf 403
echinoderms, ii, 400
echinoids, ii, 401
fishes, ii, 409, 417
foreign, ii, 395
gastropods ii, 403, 406
Silurian graptolites, ii, 408
halysites, ii, 407
in the West, ii, 390
life, ii, 396
marine plants, ii, 409
ostracodes, ii, 408
pelecypods, ii, 403, 406
Silurian Period, ii, 368
Silurian pteropods, ii, 407
sponges, ii, 408
starfishes, ii, 401
system, subdivisions of, ii, 370
trilobites, ii, 403, 408
Silverton series, iii, 572
Simiidae, iii, 289
Simoedosaurus, iii, 181
Simpson series, iii, 563
Sioux quartzite, ii, 173, 205;
"i, 559
Siphonalla marylandica, iii, 294
Sirenia, iii, 229
Sivatherium, iii, 323
Siwalik formation, iii, 300
Skertchly, S. B. J., cited, i, 23;
iii, 516; (and Kingsmill),
407, 424
Slate, i, 473
Slaty structure, i, 441
Slichter, C. S., cited, i, 221, 563,
576
Slickensided surfaces, meteorite,
ii, 26
Sloths, Pleistocene, iii, 498
Pliocene, iii, 321, 322
Slumps, i, 231
Smaragdite, i, 466
Smilodon, iii, 325
Smith, E. A., cited, i, 543; iii,
in, 132, 141, 142, 199,
244, 262 ; (and Aldrich), iii,
200, 244, 309; (and John-
son), iii, 302
Smith, G. O., cited, ii, 395, 555;
iii, 210, 211, 212, 214,
266, 267, 271, 315, 316,578;
(and Willis), iii, 315
Smith, J. H., cited, iii, 205
Smith, J. P., cited, ii, 639; iii,
50, 52, 63, 69, 91, 310
Smith, W. S. T., cited, ii, 209,
505; iii, 481, 565; (and
Darton), 66, 120, 121, 566
Smith River beds, iii, 568
Smock, J. C., cited, iii, 14, 357;
(and Cook), 367
Smyth, W. S., cited, ii, 149, 178,
179, 180
Snakes, Cretaceous, iii, 178
Snow, work of, i, 244
Snow-fields, i, 244
distribution of, i, 244
Snowflakes, forms of, i, 310
Snow-line, i, 245
in Andes, i, 246
in Antarctica, i, 246
in Greenland, i, 246
in Himalayas, i, 246
Soapstone, i, 431, 473
Sodipotassic rocks, i, 458
Solar nebula, origin of, ii, 51
Solarium trilineatum, iii, 294
Solenhofen limestone, iii, 75
Solidity of earth, astronomical
argument for, ii, 7
Solms-Laubach, cited, i, 652
Solution, by ground-water, i, 222
by rivers, i, 108, 122
Solution of rocks, i, 427
Solvent action, location of, i,
480
Sorby, H. C., cited, i, 367
Soudan formation, ii 150
Source of streams, i, 178
South Africa, Permian of, ii, 635
South America, Cambrian of, ii,
272
Cretaceous, Lower, iii, 129
Cretaceous, Upper, iii, 171
Devonian of, ii, 448
Eocene of, iii, 219
Jurassic of, iii, 78
Miocene of, iii, 281
Mississippian of, ii, 517
Oligocene of, iii, 252
Pennsylvanian of, ii, 591
Permian of, ii, 638
Pleistocene life of, iii, 500
Pliocene life of, iii, 321
Proterozoic of, ii, 215
Triassic of, iii, 37
South American mammals, Pleis-
tocene, iii, 498
Southall, cited, iii, 415, 516
Southern Hemisphere, Pleisto-
cene life of, iii, 500
Spacing out of planets, ii, 78-80
Spatangus, iii, 294
Spatter-cones, i, 609, 610
Spearfish beds of South Dakota,
iii, 25, 566
sandstone, iii, 565
shale, iii, 68, 566
Specific heat of rock, i, 552
Spencer, A. C., cited, ii, 435;
iii, 203
Spencer, J. W., cited, iii, 312,
382, 415, 419, 482, 521, 522
Spermatophytes, Devonian, ii,
493
geologic contribution of, i, 657
Sphaerexochus mirus ii, 403
Sphaeroceras, iii, 91
Sphenophyllales, Carboniferous,
ii, 597, 598
Devonian, ii, 493
Mississippian, ii, 537
Sphenophyllum, i, 657; ii, 602
Devonian, ii, 493
longifolium, ii, 597
Permian, ii, 643
Sphenopteris, ii, 595, 602, 643
Mississippian, ii, 537
splendens, ii, 593
Sphere of activity, ii, 62
Sphericity, a factor in deforma-
tion, i, 580
Spherosiderite, i, 466
Sphinx conglomerate, iii, 210
Spiders, Carboniferous, ii, 611
Spinel, i, 466
618
INDEX.
Spiral nebulae, motions of, ii, 43
origin of, ii, 58
Spirifer acuminatus, ii, 462, 465
arenosus, ii, 458, 465
biplicatus, ii, 520
cameratus, ii, 615, 616, 617
disjunctus, ii, 475, 476, 520, 515
increbescens, ii, 532
logani, ii, 525
micropleurus, ii, 455
marionensis, ii, 520, 521
murchisoni, ii, 458
niagarensis, ii, 403
pennatus, ii, 471
radiatus, ii, 403, 409
striatus, ii, 525, 528
suborbicularis, ii, 525
tullius, ii, 475, 476
Sp'riferina, ii, 531, 615; iii, 57
kentuckiensis, ii, 616, 617
spinosa, ii, 532
Sp'rifers, Devonian, ii, 475
Genevieve, ii, 531
Hamilton, ii, 472
Mississippian, ii, 531 .
Onondagan, ii, 464
Pennsylvanian, ii, 615
Silurian, ii, 404
Sp.rorbis, iii, 294
Sp'sula, iii, 295
(Hamimactra) marylandica,
iii, 292
Spits, i, 357
Spokane shale, iii, 569
Sponges, Cambrian, ii, 287
Devonian, ii, 467
Jurassic, iii, 85
Osage, ii, 525
Ordovician, ii, 363
secretions of, i, 661
Silurian, ii, 408
Triassic, iii, 57
Sponglten Kalk, iii, 85
Sporadosiderites, i, 5
" Spouting horn," i, 351
Spring Creek black shale and
limestone, ii, 562; iii, 560
Spring deposits, Pleistocene, iii,
446
Springer, F., (and Wachsmuth,)
cited, ii, 400, 523, 526
Springs, i, 235
Spurr, J. E., cited, ii, 308, 390,
436, 506, 552; iii, 67, 250
Spy, men of, iii, 326
Squalodon, iii, 294
Squaloraja polyspondyla, iii, 87
Squamata, iii, 42, 43, 180
Squatina speciosa, iii, 86
Squatinidae, iii, 85
Stalactite, i, 437, 473
formation of, i, 227
Stalagmite, i, 437, 473
Stampiati stage of Oligocene, iii,
250
Stanton, J. W., cited, iii, 108,118,
119, 134, 160, 242 ; (and Dil-
ler), iii, 122; (and Hatcher),
iii, 152; and (Knowlton),
i", 159
Stapff, F. M., cited, i, 388
Star Peak formation, iii, 28, 70
Starfishes, Mississippian, ii, 523
Silurian, ii, 401 .»
Triassic, iii, 57
Stassfurt, salts of, ii, 630
State Quarry beds, ii, 432; iii,555
Staurocephalus, ii, 411
murchisoni, ii, 403
Staurolite, i, 466
Steam from volcanoes, i, 635
Steatite, i, 431, 466, 473
Stegosauria, iii, 97,99
Stegosaurus, iii, 100
Stehlin, H. G., cited, iii, 284
Steinman, G., (and Moricke,)
cited, iii, 281
Stellar collision, ii, 53
Steneofiber, iii, 253
Stenotheca rugosa, ii, 284
Stephanites superbus, iii, 54
Sterculia, iii, 173
mucronata, iii, 174
Stereospondyli, iii, 42
Stereosternum, ii, 649
Sternbergia, ii, 601
Stevenson, D., cited, i, 341, 344,
370
Stevenson, J. J., cited, ii, 580;
iii, 382
Stigmaria, ii, 600, 602
Stockton formation, iii, 10
Stock, H. H., cited, ii, 546
Stoliczka, F., cited, iii, 171
Stone, G. H., cited, iii, 334,
361, 370, 372, 375, 379, 403,
494
Stoney, G. Johnstone, cited, ii,
92,93
Stoping, i, 632
Storrs, L. S., cited, iii, 159
Stoss side, i, 299
Strachey, R., cited, i, 51
Strata of Alabama, section of, iii,
451
of Arizona, section of, iii, 575
of Arkansas, sections of, ii,
562; iii, 560
of Black Hills, section of, iii,
566
of California, section of, iii, 577
of Colorado, sections of, ii,
563; i", 570, 572
of Eureka District, Nevada,
section of, iii, 576
of Grand Canyon region, sec-
tion of, iii, 574
of Indian Territory, section of,
iii, 562
of Indiana, section of, iii, 556
of Iowa, section of, iii, 558
of Kentucky, section of, ii, 560
of Massachusetts, section of,
iii, 546
of Michigan, section of, iii, 553
of Missouri, section of, ii, 561
of Montana, section of, iii, 568
of Nebraska, section of, Hi, 564
of Ohio, sections of, ii, 560;
iii, 554, 555
Strata of Pennsylvania, section
of, ii, 557
of Tennessee, section of, iii,
549,550, 552
of Texas, section of, ii, 562
of Virginia, section of, iii, 548
of Washington, section of, iii,
578
of West Virginia, sections of,
ii, 558, 559J "i, 548
of Wyoming, section of, iii, 565
Stratification i, 486
Stratified rocks, i, 14
Stratigraphic geology, i, i
Stratigraphy and fossils, i, 647
and paleontology, i, 647; ii,
242
Straw formation, ii, 563
Stream erosion, i, 56-177
economic effects of, i, 108
influenced by declivity, i, 123
influenced by rock, i, 124
influenced by structure, i, 125,
127
topography developed by, i, 92
Streams, abrasion by, i, 119
adjustment of, i, 146, 147
in Appalachians, i, 148
affected by rotation of earth, i,
194
aggradational work of, i, 177-
204
antecedent, i, 169, 171
characteristics of aggrading, i,
179, 187
compared with glaciers, i, 262
consequent, i, 78
corrasion by, i, 119
cross-currents in, i, 117
decrease in size of, i, 179, 180
deposition by, i, 177
drowning of, i, 170
effect of change of level on, i,
161, 171
erosion by, i, 57~i77
floods of, i, 109
ice of, i, 118
intermittent, i, 71, 72
mature, i, 86
mechanical work of, i, 226
migration from synclines to
anticlines, i, 159
mineral matter in solution in,
i, 225
old age of, i, 89
overloading of, i, 178, 179, 186
permanent, i, 70
piracy of , i, 103
ponding of, i, 171
relation of width to meander
belt, i, 193
solution by, i, 108, 122
sources of, i, 178
struggle for existence among,
i, 100
superglacial and englacial de-
posits of, iii, 376
superimposed, i, 150
topographic adjustment of, i,
162, 163, 197
INDEX.
619
Streams, transportation by, i,
115, n6
velocity of, i, 115
young, i, 85
Stream-terraces, i, 204-212
Stream velocity, effect on trans-
portation, i, 115
Stream work, i, 57-212
Streptelasma corniculum, ii, 361
Streptis, ii, 411
grayi, 11,403
Stress-accumulation, i, 583, 588
Striae, i, 283
Striation, glacial, iii, 346
Strike, i, 501
Strike fault, i, 522
Strobilops labyrinthica, iii, 410
Stromatopora, ii, 361, 457
del.catula, ii, 358
Stromboli, i, 636
Stropheodonta, ii, 464, 478
concava, ii, 462
magnifica, ii, 458
profunda, ii, 403
Strophomena, ii, 456
subtenta, ii, 356
Strophonella punctulifera, ii, 455
Strotospongia maculosa, ii, 363
Structural adjustment of valleys,
i, 147
Structural features of rocks, i,
486-525
arising from disturbance, i,
500
Structural geology, i, i, 486
Structural valleys, i, 77
Structure of earth on nebular
hypothesis, ii, 133
on planetesimal hypothesis, ii,
133
Structure of glacier ice, i, 308
of igneous rocks, i, 498
of rock, influence on erosion,
i, 125
of sedimentary rock, i, 486
Struggle for existence among
valleys, i, 100
Stuart shale, iii, 562
Sturgeon quartzite, ii, 179, 180
Styliola, ii, 473
Subaerial erosion, i, 58
Sub-Aftonian drift, iii, 383, 387
Sub-atomic forces, causes of
crustal movement, i, 556
Sub-Carboniferous period, ii,
496 (see Mississippian)
Subdivisions of geology, i, i
Subglacial load, i, 282
submerged channels, iii, 521
valleys and tidal action, iii, 528
Sub-oceanic and continental sec-
tors, ii, 123
Subsidence, effect on coast-lines,
i, 33i
Subulites regularis, it, 353
ventricosus, ii, 403
Succession of faunas, Cambrian,
ii, 294
Ordovician, ii, 364
Succinea avara,iii,4io
Succinea obliqua, iii, 410
Suess, E., cited, i, 538; ii, 129,
589
Sugarloaf arkose, iii, 546
Suina, iii, 236
Sulphur, i, 466
Sulphur Creek formation, iii,
313
Sulphur springs, i, 235
Sunbury shale, ii, 500, 560; iii,
554
Sun-cracks, i, 373, 490
Sundance formation, iii, 565, 566
Sunder land formation, iii, 450
Superglacial load, i, 282
Superimposed streams, i, 150
Surcula biscatenaria, iii, 294
Surface moraines, i, 266
Surface temperature on planet-
esimal hypothesis, ii, 69
Susquehanna River, i, 168
Swauk formation, iii, 210, 211,
578
Sweden, Archean of, ii, 159
Proterozoic of, ii, 215
iron ore in, ii, 216
Triassic of, iii, 34
Swedenborg, E., cited, ii, 4
Sweet, E. T., cited, iii, 367
Sweetland creek shales, iii, 558
Switzerland, Miocene of, iii, 276
Oligocene of, iii, 250
snow-fields of, i, 245
Triassic of, iii, 36
Sycamore limestone, ii, 511
Syenites, i, 415, 452, 473
Sylamore sandstone, ii, 562;
iii, 560
Sylvan shale, iii, 563
Symborodon, iii, 255
Synapsida, ii, 647, 649; iii, 42
Synbathocrinus wortheni, ii, 525
Syncline, i, 157, 504
Synclinoria, i, 504
Syndyoceras cooki, iii, 256
Syringopora, Silurian, ii, 407
verticillata, ii, 406
Syringothyris subcuspidatus, ii,
525
Syssiderites, i, 5
Systemodon, iii, 235
Tachylite, i, 473
Taconic mountains, folding of,
ii, 333
Ordovician of, ii, 326
Taconic system, ii, 335
Taeniaster cylindricus, ii, 359
Tseniopteris, .ii, 643
newberriana, ii, 643
Taff, J. A., cited, ii, 209, 224,
308, 321, 435, 504, 511,
543, 548; "i, 115, 560, 562;
(and Brooks), 548
Tait.P.G., cited, i, 552,572,573!
(and Thompson), 560, 579
Talc, i, 466
Talchir formation, ii, 634
Talcose rock, i, 431
Talus, i, 112
Talus, and alluvial deposits, iii,
472
cone, i, 182
glaciers, i, 232, 233; iii, 474
Tancredia bulbosa, iii, 92
Taneum andesite, iii, 267
Tapirs, Miocene, iii, 289
Pliocene, iii, 322 , 323
Tarr, R. S., cited i, 165; iii,
382, 479
Tasmania, Cambrian fossils of,
ii, 300
Taylor, F. B., cited, iii, 397, 401,
402, 404, 414, 415, 416, 419
482; (and Leverett), 396
Taylor formation, iii, 142, 143
Tdamnastraea prolifera, iii, 84
Tealoresco, E. C., cited, ii, 605
Teanaway basalt, iii, 211, 578
Tejon formation, iii, 201, 317
Teleorhinus, iii, 178
Teleosaurs, Jurassic, iii too
Teleostomi, ii, 401
Teleosts, Cretaceous, iii, 185
Jurassic, iii, 86
Tellico sandstone, n,3i6; iii, 549
Tellina, iii, 295
(Angulus) producta, iii, 292
Telluride formation, iii, 207, 572
Telotremata, ii, 356
Temnospondyli, ii, 607, 609;
iii, 42
Temperature and CO2 of ocean,
ii, 667
at center of earth, i, 571
atmospheric, i, 43 , 46, 49
based on Laplace's law, i, 546
developed by infall of plane-
tesimals, ii, 68
effect on erosion, i, 129
effects of changes on rocks, i,
44
expansion and contraction due
to changes of, i, 44
in excavations, i, 569
of interior of earth, i, 559-570
of lavas, i, 615, 627
of surface on planetesimal
hypothesis, ii, 69
Temple Butte limestone, iii, 574
Tennessee, Devonian phosphates
of, ii, 440
Ordovician phosphates of, ii,
337
river, history of, i, 168-169
section of strata in, iii, 549,
550, 552
Tension joints, i, 514
Tensional movements, origin of,
ii, 131
Tentaculites, ii, 478
Terebra, iii, 294
unilineata, iii, 294
Terebratella plicata, iii, 189
Terebratula, ii, 472; iii, 52, 57.
Qi
harlani, iii, 189
humboldtensis, iii, 53
Terebratulacea, iii, 134
Terebratuloids, Triassic, iii, 57
620
INDEX.
Terminal moraine, i, 266, 301;
iii, 362
kettles in, iii, 365
knobs in, iii, 365
near Plainfield, New Jersey,
iii, 364
topography of, iii, 363, 365
Terraces, flood-plain, i, 205
rock, i, 140, 204
stream, i, 204-212
termini of, i, 210
wave-built, i, 363
wave-cut, i, 351, 353
Terrestrial formations, Eocene,
iii, 204
organic deposits, Pleistocene,
446
Terrigenous deposits in sea, i,
379
Tetrabelodon, iii, 285, 323
angustidens, iii, 285
Tetracoralla, iii, 57
Tetradella quadrilirata, ii, 351
Tetragraptus, ii, 364
bigsbyi, ii, 362
fruticosus, ii, 362
Texas, asphalt in, iii, 116
bitumen in, iii, 116
Comanchean of, iii, 115
Comanchean fauna of, iii, 135
Cretaceous, thickness of, iii,
3i4
Eocene of, iii, 200
Marine Jurassic of, iii, 60
Miocene of, iii, 262
oil of, iii, 262
Permian of, ii, 623
Trinity series, iii, 116
Textularia, iii, 189, 294
subangulata, iii, 241
Thalassemydae, iii, 90
Thalattosauria, iii, 42, 47
Alexandra, iii, 47
Thalattosuchia, iii, 90, 100
Jurassic, iii, 100
Thallophytes Devonian, ii, 493
geologic contribution of, i, 653
Thames River, i, 224
material in solution in, i, 108
Thecosmilia tricnotoma, iii, 84
Thermal efficiency of atmos-
phere, ii, 674
Theromorpha, ii, 649,650; iii 42
Theropoda, iii, 43, 97, 176
Thinohyus, iii, 253
Thompson, G., cited, Hi, 457
Thompson, J., cited, i, 322, 560,
579
Thompson, W. G., cited, i, 119
" Thorofares," i, 358
Three Forks shale, ii, 153; iii, 70
Thrust-fault, i, 517, 518
Thurman sandstone, iii, 562
Tibet plateau, i, 548
Pliocene of, iii, 320
Tidal action and submerged
valleys, iii, 528
Tidal disruption, ii, 22
Tides, i, 4, 338
effect on rotation, i, 4
Tiger, saber-toothed, Pleisto-
cene, iii, 498
Pliocene, iii, 323
Tight, W. G., cited, iii, 382
Tilden, W. A., cited, i, 620
Tilhemic rocks, i, 457
Till, i, 473; ii'i, 360
glacial, iii, 341
Tillotherium, iii, 238
fodiens, iii, 238
Timoclea, iii, 295
Timpas shale, iii, 155, 206
Tinoceras pugnax, iii, 234
Terolitinae, iii, 53
Tishomingo granite, iii, 563
Titanite, i, 467
Titanops, iii, 255
Titanotheres, Oligocene, iii, 254
Titanotherium validum, iii, 254
Todd, J. E., cited, i, 195; ii,
205, 308; iii, 368, 382, 411
Tolman, C. F., cited, ii, 666
Tongrian stage of Oligocene, iii,
250
Tonto series, iii, 574
Topaz, i, 467
Topographic adjustment of
streams, i, 162, 163, 197
effects of glacial erosion, i, 287
effects of ground-water, i, 231
map, explanation of, i, 30
maturity, i, 86
old age, i, 89
unconformity, iii, 471
youth, i, 86
Topography, developed by river
erosion, i, 92
dune, i, 32
landslide, i, 231
mature, i, 86
of alluvial deposits, i, 196
of glaciers, i, 266
of ocean bottom, i, 326
of shallow- water deposits, i,
374
terminal moraine, iii, 363
terminal moraine, develop-
ment of, iii, 365
youthful, i, 86
Top-set beds, i, 202
Tornatellaea bella, iii, 243
Tornebbhm, A. E., cited, ii, 159,
216
Tornoceras mithrax, ii, 463
Toro formation, iii, 68, 577
Toronto interglacial beds, iii, 490
fauna, iii, 492
flora, iii, 491
Tower, G. W., cited, ii, 266
Toxodontia, iii, 321
Trachodon, iii, 178
Trachyceras austriacum, iii, 51
Trachydomia wheeled, ii, 616
Trachyte, i, 473
Tragulidae, iii, 256, 285
Tragulina, iii, 236
Tragulus, iii, 256
Transportation, i, no
by glaciers, i, 281
by ocean currents, i, 367
Transportation, by streams, i,
US, no
by waves, i, 354
by wind, i, 22, 25
Trap, i, 419, 473
Traquair, R. H., cited, ii, 489,
653
Traverse group, iii, 553
Travertine, i, 473
Tree ferns, Devonian, ii, 493
Trees, uprooting of, i, 40
Tremodoc slates, ii, 271, 343
Tremataspis, ii, 484, 485
Trematis millipunctata, ii, 356
Tremolite, i, 447, 467
Trenton limestone, ii, 310; iii,.
553, 555, 557
Triarthus beckii, ii, 350
Triassic ammonites, iii, 50, 52, 56
arthropods, iii, 57
brachiopods, iii, 53
brittle-stars, iii, 57
bryozoans, iii, 57
cephalopods, iii, 51, 53, 56
ceratites, iii, 52, 54, 56
chelonians, iii, 43
coal-beds of Germany, iii, 41
coal-beds of Scandinavia, iii,.
4i
conifers, iii, 39, 41
corals, iii, 57
cordaites, iii, 39
crinoids, iii, 57
crocodilians, iii, 43
cycadeans, iii, 39, 41
cycads, iii, 39
dinosaurs, iii, 43
dolichosaurs, iii, 43
echinoderms, iii, 57
echinoids, iii, 57
equiseta, iii, 40
equisetales, iii, 38
faunas, iii, 52
flora of North Carolina, iii, 40
flora of Virginia, iii, 40
foraminifers, iii, 57
gastropods, iii, 56
ginkgos, iii, 40
goniatites, iii, 56
gymnosperms, iii, 38, 41
ichthyopterygians, iii, 46
ichthyosaurians, iii, 45, 46
labyrinthodonts, iii, 42
land animals, iii, 41
lizards, iii, 43
lycopods, iii, 39
mammals, iii, 44
marine reptiles, iii, 45
Middle, faunas, iii, 54
nautiloids, iii, 56
nothosaurs, iii, 45
orthoceratites, iii, 56
pelecypods, iii, 54, 56
Triassic Period, iii, i
climatic conditions of, iii, 2Q>
close of, iii, 29
faunal changes of, iii, 50
life of, iii, 38
marine changes of, iii, 48
marine life of, iii, 48
INDEX.
621
Triassic Period, plant life of,
i", 38
transition faunas of, iii, 49
Triassic plesiosaurians, iii, 45
pteridophytes, iii, 38
pythonomorphs, iii, 43
reptiles, iii, 42
sauropterygians, iii, 45
sigillarias, iii, 39
sponges, iii, 57
starfishes, iii, 57
Triassic System, Africa, iii, 38
alabaster of, iii, 34
Asia, iii, 37
Australia, iii, 38
coal-beds of, in Virginia, iii, 17
eastern United States, iii, 2
England, iii, 33
Europe, iii, 30, 35
general provinces of, iii, 38
Germany, iii, 31
gypsum of, iii, 25, 29, 34, 35
interior, thickness of, iii, 27
map of, iii, 3
Pacific slope, iii, 27
Red Beds of, iii, 25
relation to Jurassic, iii, 47
relation to Permian, iii, 47
Russia, iii, 34
salt of, iii, 25, 29, 34, 35
South America, iii, 37
Sweden, iii, 34
West, iii, 24
Triassic terebratuloids, iii, 57
thalattosaurians, iii, 45
turtles, iii, 43
Upper, faunas, iii, 55
Tributaries, development of, i, 78
position of, i, 79
topographic adjustment of, i,
197
Triceratops, iii, 176
prorsus, iii, 177
Trigonia, iii, 82, 91, 135, 187
emaryi, iii, 135
eufaulensis, iii, 187
navis, iii, 83
Trigonocarpus, Mississippian, ii,
537
Trilobites, Cambrian, ii, 281, 297
Carboniferous, ii, 616, 618
Devonian, ii, 467, 477
Genevieve, ii, 533
Hamilton, ii, 473
Helderbergian, ;i, 456
Kinderhook, ii, 520, 521
Mississippian, ii, 525
Ordovician, ii, 347, 349
Oriskany, ii, 459
Silurian, ii, 403, 408
Upper Cambrian, ii, 300
Trimerella, ii, 404
acuminata, ii, 403
ohioensis, ii, 403
Trinacromeron osborni, iii, 181
Trinidad formation, iii, 153, 154,
206
Trinity series, Texas, iii, 116
Trinucleus concentricus, ii, 367
ornatus, ii, 349
Trionychia, iii, 178
Tripoli, i, 661 ; iii, 260
Tripolite, i, 426
Tritia, iii, 294, 295
Tritoniidae, iii, 295
Trocholites ammonius, ii, 352
Trochus, sp., iii, 135
saratogensis, ii, 284
Troostocrinus reinwardtii, ii, 403
Tropidoleptus carinatus, ii, 471,
472, 478
Tropites subbullatus, iii, 51
Tropitidae, h, 655; iii, 50
Trout creek, i, 193
Truckee Miocene, iii, 266
Truncatulina lobatula, iii, 241
Tschermak, G., cited, i, 538; ii,
27, 28
Tschernyschew, T., cited, ii, 391
Tufa, see Tuffs
Tufa cones, i, 611
deposits, i, 6n
Tuffs, i, 404, 434, 473
Tuicla, iii, 294
Tullahoma formation, iii, 552
Tully limestone, ii, 432, 477
Turbo, iii, 91
moyonensis, iii, 136
Turkestan, loess of, iii, 407
Pennsylvanian of, ii, 589
Pleistocene of, iii, 424
Turner, H. W., cited, iii, 122,
160, 263, 265, 267, 475;
(and Lindgren), 317
Turrilites, iii, 134
Turritella, iii, 134, 295
budaensis, iii, 135
mortoni, iii, 243
variabilis, iii, 294
Turtles, Cretaceous, iii, 178
Jurassic, iii, too
marine, Cretaceous, iii, 180,185
Triassic, iii, 43
Tuscaloosa series, iii, in, 112,
114
thickness of, iii, 115
Tuscarora deep, i, 548
Tuscarora quartzite, iii, 548
Two Medicine River, i, 154, 157
Tyler slate, ii, 186, 189
Tyndall, J., (and Huxley,) cited,
1,322
Typotheria, iii, 321
Tyrrell, J. B., cited, ii, 426;
iii, 152, 236, 332, 362, 368
Undina gulo, iii, 88
Unguiculata, iii, 230
Ungulata, iii, 230
Unicoi formation, ii, 152
Unio douglassi, iii, 134
farri, iii, 134
United States Geological Survey,
i, 32
Unkar formation, iii, 574
Unkpapa sandstone, iii, 68, 566
Upham, W., cited, i, 388; iii,
361, 367, 370, 393, 402, 403,
411,415,424,481,482, 516,
521
Upper Aubrey formation, iii, 313,
574
Upper Barren Coal Measures, ii,
542
Upper Burlington limestone, ii»
56i
Upper Cambrian, ii, 225
annelids, ii, 299
brachiopods, ii, 299, 300
cephalopods, ii, 299
corals, ii, 299
cystids, ii, 299
gastropods, ii, 299, 300
pelecypods, ii. 299
trilobites, ii, 299, 300
Upper Devonian, ii, 430
map, ii, 431
Upper Forestian epoch, iii, 421
Upper Permian, gypsum in, ii>
630
salt beds of, ii, 630
Upper Productive Coal Measures,
ii, 541
Upper Silurian, ii, 368; (see
also Silurian)
Upper Triassic faunas, iii, 55
Upper Turbarian epoch, iii, 421
Uprooting of trees, i, 40
Upshur sandstone, iii, 548
Uralite, i, 431
Uruguay river, sediment carried
by, i, 107
Usiglio, cited, i, 375; ii, 661
Utica shale, ii, 310; iii, 553, 555*
557
Uvigerina, iii, 294
Vaginalina legumen, iii, 241
Valley trains, iii, 371
Valleys, affected by folds, i, 154.
antecedent, see Streams, an-
tecedent
canoe-shaped, i, 155
consequent, i, 78
courses of, i, 77
development of, i, 63, 70, 73,.
80
hanging, i. 164, 290
limits of growth, i, 67
oldest parts, i, 76
profiles of, i, 66
relations to lakes, i, 74
slopes of, i, 94
special forms of, i, 94
structural, i, 77
struggle for existence among,
i, 100
submerged, iii, 521
Van Hise, C. R., cited, i, 219
434. 448, 474, 479, 5<>4,
543, 555, 57o; ii, 138, 139,
143, 145, 146, 149, 150, 153,
155, 158, 176, 178, 179, 180,
181, 186, 187, 188, 191 , 198,
199, 205, 206, 208, 213,
214, 217; (and Hoskins), ii,
258
Vanuxem, L., cited, ii, 310
Vanuxemia dixonensis, ii, 354
Vaquero formation, iii, 68, 577
622
INDEX.
Variscan Alps, ii, 589
Vaughan, J. W., cited, iii, 115,
242, 300; (and Hill), 142,
143. 302
Veatch, A. C., (and Harris,)
cited, Hi, 411
Vegetation, effect on dunes, i, 29
effect on erosion, i, 131, 644
effect on sediments, i, 645
effect on weathering, i, 131
Eocene, iii, 226
land, Pliocene, iii, 320
Oligocene, iii, 252
terrestrial, Comanchean, iii,
130
Miocene, iii, 282
Veins, i, 223, 428, 511
Venericardia marylandica, iii,
243
Venerupls, iii, 295
Venus, iii, 295
ducatelli, iii, 292
Vermes, geologic contribution of,
i, 662
Miocene, iii, 294
Vermeule, C. C., cited, i, 109
Vermiceras crossmani, iii, 91
Vermilion Cliff formation, iii,
313
district, ii, 150
group, iii, 208
region, Animikean of, ii, 190
(Minn.) region, Huronian of,
ii, 180
Vertebrates, geologic contribu-
tion of, i, 663
marine, Cretaceous, iii, 180
Eocene, iii, 239
Jurassic, iii, 85
Kinderhook, ii, 519
Ordovician, ii, 347
Triassic, iii, 45
Vertebrata, terrestrial, Coman-
chean, iii, 133
Cretaceous, iii, 175
Eocene, iii, 288
Jura-Comanchean, iii, 97
Miocene, iii, 283
Mississippian, ii, 537
Oligocene, iii, 253
Pennsylvanian, ii, 606
Permian, ii, 666
Pleistocene, iii, 495
Pliocene, ii, 321
Triassic, iii, 41
Very, F. W., cited, ii, 674
Vesuvius, i, 605
Viburnum, iii, 173
inaequilaterale, iii, 174
Vicksburg formation, iii, 199,
244
Vienna basin, Miocene of, iii,
277
Oligocene of, iii, 250
Pliocene of, iii, 319
Vincentown limesand, iii, 189
Viola limestone, Hi, 563
Virginia, natural bridge of, i, 156
section of strata in, iii, 548
slate, ii. 190
Virginia, Triassic coal-beds of,
iii, 17
Triassic flora of, iii, 40
Viridite, i, 467
Vishnu formation, ii, 153; iii,
574
Vishnutherium, iii, 323
Vitulina pustulosa, ii, 471, 472
Viverridae, iii, 237
Viviparus montanaensis, iii, 134
Volcanic action, causes of, i,
623-633
climax of, ii, 116
periodicity of, i, 607
Volcanic ash, i, 23, 404, 592, 617
bombs, i, 406, 592, 617
cinders, i, 592
cones, i, 500
debris in sea, i, 381
differentiation of earth mat-
ter, ii, 120
dust, see Volcanic ash
eon, ii, 91
eruptions, i, 594
and atmospheric pressure, i,
606
and tidal strain, i, 607
types of, i, 593
gases, i, 617-623
action of, i, 617
kinds of, i, 618
proportions of, i, 620, 622
sources of, 1,619-621, 633
glass, see Obsidian
in sea, i, 381
mud, i, 380, 610
neck, i, 500
plug, i, 500
rocks, i, 395-418
rocks, residual gases in, i, 619
smoke, i, 592, 617
Volcanoes, i, 599-611
coincidence in eruption of, i,
606
cones of, i, 608
distribution of, in curved lines,
i,6o3
in latitude, i, 603
in relation to crustal move-
ments, i, 601, 604, 628
in relation to land and sea,
i, 599
in time, i, 599
independence of, i, 605, 623
periodicity of, i, 607
relations of, i, 604-607
Voltzia, ii, 645-646
heterophylla, ii, 645
Volume of ocean, i, 325
Von Huene, cited, iii, 44
Von Richthofen, F., cited, iii,4O7
Vuggs, i, 437
Vulcan formation, ii, 187
Vulcanism, i, 2, 590-637
causes of, i, 623-633
dynamics of rise of lava, ii, 103
effects on coast-lines, i, 332
heat of, ii, 91-101
initiation of, ii, 99
marine, i, 332
Vulcanism, mode of extrusion,
ii, 102
Pleistocene, iii, 447
Pliocene, iii, 315, 317
time relations to atmosphere,
ii, 106
Vulcanism and deep sedimen-
tation, i, 629
and ground- water, i, 635
and rotation, i, 603
Waagenoceras cumminsi, ii, 654
Wabaunsee formation, in, 564
Wachsmuth, C., (and Springer,)
cited, ii, 400, 523, 526
Wacke, i, 422, 473, 645
Wad, i, 467
Walchia, ii, 645
piniformis, ii, 644
Walcott, C. D., cited, i, 194,
246, 371, 438, 440, 441, 502,
503, 509; ", 153, 210.
218, 224, 225, 240, 249,
263, 264, 265, 280, 283,
296, 324, 334, 335, 347,
348, 366, 412, 435, 506,
623; iii, 481, 574, 576
Walden sandstone, iii, 551
Wallace, A. R., cited, i, 665,
668; iii, 150
Walnut family, rate of migra-
tion, iii, 533
Walther, J., cited, i, 50, 670
Wanner, A., cited, iii, 40
Wapanucka limestone, iii, 562
Wapsipinicon formation, iii, 558
Ward, L. F., cited, iii, 39, 40,
59,94, 119, 131, 132
Warming, E., cited, i, 667
Warping, effect of, on streams
i, 171
of earth's crust, i, 526, 541 , 542
Warsaw formation, ii, 561
Wartburg sandstone, iii, 549
Wasatch mountains, lateral mo-
raines of, i, 303
Wasatch stage of Eocene, iii, 208
Washington, H. S., cited, i, 412
451, 573
Washington, loess in, iii, 409
section of strata in, iii, 578
Washington gneiss, iii, 547
sandstone, iii, 560
sandstone, and shale, ii, 562;
iii, 560
Washita series, iii, 116
Wassemer beds, iii, 308
Waste of glaciers, i, 273
Water, see Streams, Ground-
water, Ocean, etc.
amount of. i, 7
geologic activity of, i, 8
Waterfalls, i, 132
development of, i, 133
Minnehaha, i, 137
Niagara, i, 139
age of, iii, 415
St. Anthony, i. 1-35
age of, iii, 415
Shoshone, i, 135
INDEX.
623
Waterfalls, Upper Yosemite, i,
138
Yellowstone, i, 135
Waterfalls and sediment, i, 137
Water-gaps, i, 141, 167
Waterhme, i, 473
fauna, ii, 412
formation, 11,389,424; iii, 556
Water-table, i, 71, 215
Water- vapor, as a thermal fac-
tor, in, 444
climatic effects of, i, 643
Wave erosion, i, 342-354
and horizontal configuration,
i, 353. 363, 364
range of, i, 346
topographic features developed
by, i, 349
Wave-built terraces, i, 363
Wave-cut terraces, i, 351 •, 352
Wave-marks, i, 490
Wave-motion, i, 339
Waverly brachiopods, ii, 527
crinoids, ii, 526
fauna, ii, 526
pelecypods, ii, 527
shales, ii, 502, 511, 560
Waves, i, 339
deposition by, i, 355
erosion by, i, 342-354
force of, i, 344
transportation by, i, 354
work of, i, 342-366
Wealden Crag, iii, 128, 318
Weathering, i, 54, no, 226
affected by life, i, 644
aided by plants, i, 112
aided by hot vapors, i, 1 13
effect of gravity, i, 112
effect of joints, i, 151, 153
importance of, in valley
growth, i, 114
Webberville formation, iii, 143
Weber conglomerate, iii, 576
limestone, ii, 154, 563; iii,
157, 570
Wedgework of ice, i, 45, 48, 150
of roots, i, 112, 131, 150
Weed, W. H., cited, i, 225, 237,
474, 656; ii, 153. 210, 267,
436; iii, 120, 210, 212,
568; (and Iddings), iii, 156,
159; (and Pirsson), iii, 120
Weeks, F. B., cited, ii, 280, 506,
553
Weller, S., cited, ii, 318, 349,
350, 378, 403, 4io, 411,
425, 436, 438, 452, 453,
455, 458, 463, 474, 475,
501, 520, 525, 532, 616,
617; (and Kummel), 266;
iii, 137, 189; (and Knapp),
iii, 140, 187
Wells, artesian, i, 242
flowing, i, 234, 242, 243
Wenlock series, ii, 396
Wenonah beds, iii, 187
West Elk breccia, iii, 157, 57O
West Indies, Eocene of, iii, 220
Oligocene of, iii, 244
West Virginia, section of strata
in, iii, 548
Western interior coal-field, ii,
548
Western mountains, glacial de-
posits in, iii, 467
Wetumka shale, iii, 562
Wewaka formation, iii, 562
Wewee slate, ii, 150, 179
Weyburn Crag, in, 318
Whalen group, iii, 565
Wheeling well, temperature of, i,
569
White, C. A., cited, iii, 106, 122;
(andSchuchert), 124, 132
White, C. D., cited, ii, 635
White, D., cited, ii, 509, 540, 546,
595
White, I. C., cited, ii, 440, 540,
558, 57<1, 619, 638; iii, 367,
382
White Cliff formation, iii, 313
White glacier, i, 263
White limestone, iii, 199
White Pine shale, iii, 576
White River formation, iii, 245,
566
Whiteaves, J. F., cited, ii, 280,
429; iii, 120
Whitetail conglomerate, iii,
210
Whitfield, J. E., (and Gooch,)
cited, i, 236
Whitfield, R. P., cited, ii, 280
Whitney, J. D., (and Hall,)
cited, ii, 314; iii, 67, 265,
516; (and Gabb), 122
Whittle, C. L., cited, ii, 211
Whittlesey, C., cited, iii, 367
Wichita formation, ii, 623
Wilchens, O., cited, iii, 171
Wildcat formation, iii, 310
Wilder, F. A., cited, ii, 621;
iii, 205
Williams, E., cited, iii. 384
Williams, G. H., cited, ii, 145,
439
Williams, H. S., cited, i, 658;
ii, 384, 391, 395, 420, 424,
452, 475, 477, 5oo, 530,
562; (and Gregory), 422,
434; iii, 560
Willis, B., cited, i, 157, 168, 169,
257, 344, 355, 365, 5i6,
543,550; ii, 210,300; (and
Blackwelder and Sargent),
273; "i, 144, 165, 202, 274,
316, 334, 352; (and Smith,
G. O.), "i, 315
Williston, S. W., cited, ii, 624;
iii, 25, 26, 66, 89, 119,
146, 149, 179, 180. 181, 497,
5i6
Willmott, A. B., cited, ii, 181
Winchell, Alex., cited, ii, 10
Winchell, H. V., cited, i, 474
Winchell, N. H., cited, ii, 150,
320; (and Ulrich), ii, 310,
314; iii, 344, 367, 370, 4",
415, 419, 516
Wind, abrasion by, i, 38
effects on plants, i, 40
movements of sea, generated
by, i, 336
transports organisms, i, 41
work of, i, 21-41
Wind River group, iii, 208
Wind-blown dust, i, 22
Wind-blown sands, i, 25
Wind-ripples, i, 37
Winslow, A., cited, i, 474; ii,
337, 575; i", 4U
Wisconsin drift, iii, 383, 390
earlier glacial stage, iii, 392
later glacial stage, iii, 393
lead in, ii, 337
map of southern, ii, 393
river, dells of, i, 152
Wisconsin, zinc in, ii, 337
Wise formation, ii, 559
Wolff, J. E., cited, ii, 213
Wood, H., cited, iii, 120
Wood, composition of, ii, 569
Woodbine formation, iii, 142
Woodbury beds, iii, 187
Woodford chert, ii, 435; iii, 562
Woodville sandstone, iii, 553
Woodward, A. S., cited, ii, 487,
488, 489, 534, 650; iii, 46,
87, 88, 256, 285
Woodward, R. S., cited, i, 560,
581; ii, 236; iii, 482, 519
Woodworth, J. B., cited, ii, 544,
549; iii, 403; (and Shaler),
8, 10, 15, 17, 18
Worthen, A. H., cited, ii, 534;
iii, 411
Worthenia tabulata, ii, 616
Wortman, J. L., cited, iii, 207,
225, 238
Wright, G. F., cited, iii, 370,
382,415,516; (and Lewis),
368
Wright, Thomas, cited, ii, 4
Wyandotte Cave, i, 227, 228
Wyman sandstone, ii, 562; iii,
56o
Wyoming, burnt coal of, iii,
153
section of strata in, iii, 565
Xenoneura antiquorum, ii, 494
Xenophora conchyliophora, iii,
294
Xiphodontidae, iii, 236
Xiphodonts, Miocene, iii, 284
Yakima basalt, iii, 267
Yarmouth interglacial forma-
tion, iii, 494
stage, iii, 389
Yazoo river, i, 188
Yellowstone park, geysers of, i,
238
hot springs of, i, 225
Yellowstone river, canyon of, i,
100
falls of. i, 135
Yellowstone series, iii, 568
624
INDEX.
Yoldia, iii, 403
Yorktown formation, iii, 260
Young, C. A., cited, ii, 542
Yukon river, delta of, i, 202
Yule limestone, ii, 154; iii, 571
Zamia, iii. 39
Zamites, iii, 39, 173
pennsylvanicus, iii, 41
yorkensis, iii, 41
Zaphrentis centralis, ii, 525
gibsonii, ii, 616
gigantea, ii, 463
ponderosa, ii, 462
Zaphrentis, Silurian, ii, 407
umbonata, ii, 406
Zaptychius carbonaria, ii, 528
Zechstein, ii, 628
Zeiler, R., cited, i, 652; ii, 591:
iii, 41
Zeolites, i, 428, 467
Zeuglodons, Eocene, iii, 239
Zinc, in Illinois, ii, 337
in Iowa, ii, 337
in Missouri, ii, 337
in Ordovician, ii, 337
in Wisconsin, ii, 337
Zircon, i, 467
Zittel, K. von, cited, i, 658, 659;
»» 4i3
Zone of accommodation, ii, 130
Zone of fracture, i, 219, 427
Zones, climatic, migration of,
Pleistocene, iii, 486
Zonites priscus, ii, 611
Zonitoides minusculus, iii, 410
Zoological provinces of Cam-
brian life, ii, 292
Zurcher, P., (and Bertrand.)
cited, iii, 252
Zygospira exigua, ii, 356
recurvirostris, ii, 356
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