there are, according to present indications, one or more pre-Wisconsin
drifts. Leverett (Monogr. LIII, p. 72) mentions several localities where
what appears to be more indurated till is encountered, sometimes at a
depth of 100 feet. Taylor (op. cit., pp. 289–290) states that “a till
older than that deposited by the Wisconsin ice-sheet seems to underlie
more or less continuously all of the later, or Wisconsin, drift in
Indiana and the southern peninsula of Michigan.” Along the western shore
of Lake Huron, north of Port Huron and along the streams, as reported by
Taylor (p. 290), there are several exposures of Illinoian till, in some
cases as much as 30 to 50 feet thick. In one case there is an old soil
at the top of this till. In such old soils it may be possible to find
fossil vertebrates of Sangamon or Peorian times, horses for example.
The fossil vertebrates found up to the present time in Michigan are not
numerous in species or individuals; all appear to belong to the middle
or late Wisconsin times. A peccary, _Platygonus compressus_, has been
found at Belding, Ionia County (p. 215). Two musk-oxen have been
discovered in the State. At Manchester, Washtenaw County, has been found
a fine skull of _Symbos cavifrons_ (p. 250). At Moorland, Muskegon
County, was obtained a skull which has been called _Boötherium
sargenti_.
Details regarding the mastodons which have been found in Michigan are
given on pages 80 to 88. Only two localities in the State have furnished
remains of _Elephas primigenius_. These are Three Oaks, Berrien County
(p. 137), and Eaton Rapids, Eaton County (p. 137). _Elephas columbi_ has
been encountered only once in the State, as far as is known; this was in
the northern part of Jackson County (p. 151).
Elephants belonging quite certainly to either _E. primigenius_ or _E.
columbi_, but for one reason or another not determined, have been found
in four localities. These are East Saginaw, Saginaw County; Macomb
County; Grand Ledge, Eaton County; and Buchanan, Berrien County. (See
page 171.)
The giant beaver, _Castoroides ohioensis_, found a congenial home in the
swamps of southern Michigan in the late Pleistocene. It has been met
with somewhere in Berrien County; at Adrian, Lenawee County; at Ann
Arbor, Washtenaw County; at Attica, Lapeer County; and at Owosso, Lapeer
County (pp. 275–276).
INDIANA.
(Map 37.)
Whoever wishes to gain a knowledge of the Pleistocene geology of
Indiana, as it is understood to-day, must study Leverett’s two great
treatises, forming Monographs XXXVII and LIII of the U. S. Geological
Survey. The first is entitled “The Illinois Glacial Lobe,” and was
published in 1899; the second has the title “The Pleistocene of Indiana
and Michigan and the History of the Great Lakes.” The portion of the
latter monograph which deals with Michigan was written by F. B. Taylor.
On pages 33 to 54 is a very full bibliography of the subject, consisting
of about 400 titles.
From the glacial map of Monograph XXXVIII, plates V and VI, the writer
has prepared map 37. This shows which part of the State has escaped
glaciation, which has been subjected to the action of the Illinoian
ice-sheet, and which has been covered by the last, or Wisconsin, glacial
ice. It will be seen that about one-sixth of the State, that forming an
irregular triangle whose apex is in Brown County and whose base is
formed by the Ohio River, has never been covered by glacial ice. North
of this is a bilobed area which is covered by till of Illinoian age. The
rest of the State (somewhat less than two-thirds of it) is overlain by
the débris left by the Wisconsin ice-sheet and subsequent deposits.
This northern area is to a great extent occupied by belts called
moraines, along which the materials are usually coarse, often full of
boulders, and frequently standing at a higher level than the surface on
each side of them. These moraines show where for long periods during its
retreat, or perhaps sometimes its advances, the ice-sheet paused and
piled up a part of its load of rocks, gravel, and sand. It will be
noticed that these moraines are somewhat concentric. On the right of the
map are seen those moraines which were left by the ice-lobe which came
down Lake Erie and later retired in that direction. Around the southern
end of Lake Michigan are the moraines laid down by the ice of the
Michigan lobe. The latter will be better seen on a glacial map of
Illinois (Monogr. U. S. Geol. Surv. XXXVIII, plate VI). In their advance
the two lobes met and coalesced and produced more or less irregular and
anastomosing moraines.
On the right hand the moraines of the Erie lobe pass on into Ohio,
where, however, they have often been given other names. On the left the
moraines of the Lake Michigan lobe continue into Illinois and retain the
same names. Both groups of moraines are prolonged into the southern
peninsula of Michigan.
On account of the comparatively recent recession of the Wisconsin
ice-sheet, the surface has not become eroded sufficiently to drain away
the water which was left in depressions of the surface. A large part of
Indiana is, or has been until recently, covered by swamps, lakes, and
ponds, and in such localities the bones and teeth of vertebrate animals
are best preserved during the early stages of fossilization. For this
reason great numbers of teeth and bones, sometimes nearly whole
skeletons, are met with in draining these swamps.
The southern border of the Illinoian drift, beginning at Cincinnati,
follows Ohio River on the Kentucky side to Jeffersonville, then passes
west of north into Brown County, whence, turning southwest, it strikes
the East Fork of White River in Du Bois County; thence, following White
River a short distance, it crosses the Wabash in Posey County.
Northward, along this terminal moraine (map 37, figs. 1, 2) of the
Wisconsin drift, the Illinoian, passing beneath this, disappears from
the surface.
The surface of the Illinoian area is better drained than the Wisconsin
area. Fewer fossils are found, and on various accounts they are of less
value. Usually the exact locality and kind of deposit is not recorded.
They may be found washed out of river and creek banks and may have in
reality been buried in sediments that were laid down in Wisconsin times
by the streams that carried away the mud, sand, and gravel from the
glacier. The driftless area has been exposed for many geological ages to
the influence of physical and chemical agencies. Its surface is,
therefore, more diversified by hills and valleys and streams. In the
limestones of this region caves are likely to be found, and these now
and then furnish fossil bones and teeth.
During more than one of the glacial stages, perhaps during the earliest,
the Ohio has served as the drainage-way for the waters that escaped from
the glacial front. This subject is discussed by Leverett in Monograph
XLI of the U. S. Geological Survey. As a result of this conveyance of
glacial waters, the great trough of this stream may contain here and
there deposits of the Illinoian stage or even of older deposits. Remains
of _Megalonyx_ (p. 32) and of a horse (p. 186) have been found in the
right bank of the Ohio, at Evansville, Indiana. At Bigbone Lick,
Kentucky, close to the Ohio, horses have been discovered, _Mylodon_ and
_Megalonyx_. These seem to occur in Sangamon interglacial beds overlying
the Illinoian.
The Illinoian drift, probably everywhere in central and northern
Indiana, underlies the Wisconsin. For some miles back from its terminal
moraine the Wisconsin drift is thin; and possibly the Illinoian may. be
found exposed in creek or river banks, or in railroad cuts. Furthermore,
Leverett (Monogr. LIII, p. 72) writes:
“Probably a considerable number of the heavy deposits of drift in
central and northern Indiana are of pre-Wisconsin age, but as they
are largely sand and gravel, or loose-textured material, they can
not easily be discriminated from the Wisconsin.”
Such deposits are likely to be covered by only a thin layer of Wisconsin
till. In many places in Indiana there have been found, deep down in the
drift, old soils, muck beds, and vegetation in various forms. These beds
appear to indicate interglacial deposits, most probably the Sangamon.
Now, various genera of vertebrates, among them horses, tapirs, and
mylodons, are not known to have existed after the Wisconsin glacial
stage. If, however, remains of such animals should be collected in
central or northern Indiana, or Ohio, or in southern Michigan, they
might be reported as having been found in late Wisconsin beds, when
really they had been derived from pre-Wisconsin interglacial soils.
It is interesting to observe that when the Wisconsin ice-sheet began to
withdraw lakes began to form along its borders. One of these, Lake
Chicago, appeared at the south end of the present Lake Michigan and for
a long time discharged its waters down Illinois River. Another, Lake
Maumee, occupied the basin of Maumee River as far west as Fort Wayne,
and emptied down the Wabash. For details connected with the close of the
Pleistocene in the region of Lake Michigan the reader should consult
Frank C. Baker’s “The Life of the Pleistocene, or Glacial Period” (Univ.
Ill. Bull. XVII, 1920).
A brief mention will be made here of the principal Pleistocene
vertebrates that have been found in Indiana; also the localities where
found, together with citations of the pages where fuller information is
furnished.
The ground-sloth _Megalonyx_ has been collected near Evansville (p. 32).
With it were secured remains of an undetermined bison (p. 257), a
Virginia deer (p. 228), a horse (p. 186), a tapir (p. 203), and the dog
_Ænocyon dirus_ (p. 32). Peccaries have been found in Gibson County (p.
216), in Wabash County (p. 218), and two species at Williams, Lawrence
County (p. 217). At the same place was discovered the shell of a
box-tortoise. Remains of deer have been discovered somewhere in
Vanderburg County, including the existing deer and an extinct species,
_Odocoileus dolichopsis_; at Harrisville, Randolph County; and at Roann,
Wabash County. Bisons of an extinct species have been secured at
Vincennes (p. 258).
The existing bison appears to have been found in Jasper County (p. 268).
Of musk-oxen, _Symbos cavifrons_ has been collected at Hebron, Porter
County (p. 252); at Wailesboro, Bartholomew County (p. 251); somewhere
in Randolph County (p. 252); and probably in Beaver Lake, Newton County
(p. 252). The existing musk-ox, _Ovibos moschatus_, has been discovered
near Richmond (p. 252).
Mastodon remains are not uncommon, especially in the northern half of
the State. It is hardly to be supposed that these animals were more
abundant there during the late Pleistocene than in many other places in
the region east of the Mississippi. The conditions for their
preservation were evidently more favorable there than anywhere else,
unless in Orange County, New York. Burial in swamp mud kept the bones
from decay; and the imperfect drainage protected them from destruction
by erosion. The various finds are described on pages 88 to 100.
Elephants are less well represented in Indiana than are the mastodons,
but are not rare (pp. 138, 151, 171). Two species were present in the
State, _Elephas primigenius_ and _E. columbi_. Beavers were doubtless
abundant, but there appears to be no definite record of any find.
However, the giant beaver has been recorded from several localities (pp.
276 to 278).
The great extinct dog _Ænocyon dirus_ was first found near Evansville
(p. 32), and the coyote, _Canis latrans_, has been reported from Boone
County. The latter is said to have been found in association with the
mammoth (Cope and Wortman, 14th Ann. Rep. Geol. Surv. Indiana, p. 7).
ILLINOIS.
(Map 38.)
As a foundation for a knowledge of the Pleistocene geology of Illinois,
the student must take Leverett’s work entitled “The Illinois Glacial
Lobe.” This is Monograph XLVIII of the U. S. Geological Survey, a volume
of 817 pages, with maps and figures. For a knowledge of the changes
which occurred around the south end of Lake Michigan on the retirement
of the Wisconsin glacier, see Dr. Frank C. Baker’s work, “The Life of
the Pleistocene, or Glacial, Period” (Univ. Ills. Bull. XVII, 1920).
Illinois is eminently a glaciated State, as is to be recognized on
Leverett’s plate VI. A little triangle in the northwestern corner,
comprising about 600 square miles, and an irregular tract of perhaps
3,000 square miles at the southern end of the State constitute the whole
of the unglaciated area out of 56,650 square miles. Two glacial stages
are prominent, the Wisconsin and the Illinoian. The first was laid down
by the Lake Michigan lobe, which sent its icy mass southwestward as far
as Shelbyville. Westward the border moraine extends to Peoria, then
north to west of Princeton, then northeast to enter Wisconsin 55 miles
west of Lake Michigan. Eastward, of course, the deposits of till and the
moraines extend into Indiana. North of the Shelbyville moraine is the
Champaign. A more powerful moraine is the Bloomington, which forms a
loop through the State, extending from Danville, Illinois, through
Bloomington to Peoria, where it appears to have overridden the
Shelbyville and thence northward, forming the outer border of the
Wisconsin drift area. North of this moraine is located that called the
Marseilles, while sweeping around the south end of Lake Michigan into
Indiana and Michigan is the Valparaiso system.
South and west of the area of the Wisconsin drift is the Illinoian. At
Mount Vernon the border crosses the Wabash and traverses Illinois,
striking the Mississippi River at Carbondale. It then follows the
Mississippi north to a point above Keokuk, where it enters Iowa. It
reenters Illinois between Rock Island and Clinton and extends into
Wisconsin.
On Leverett’s map (Monogr. XXXVIII, plate VI) there is indicated in
northern Illinois, between the Illinoian and the Wisconsin, a tract
supposed to belong to the Iowan; but Alden (U. S. Geol. Surv., Prof.
Pap. 106, 1918, p. 173) holds that there is no good evidence that the
Iowan extends into southern Wisconsin and Illinois. The supposed Iowan
(op. cit., plate III) is mapped as Illinoian.
The glacial stage which preceded the Illinoian is the Kansan. This in
Iowa extends eastward to the Mississippi, and one might naturally expect
that it would be found underlying the Illinoian east of the river.
Leverett (Monogr. XXXVIII, p. 105) presents evidences of its presence in
western Illinois. Among these evidences is the presence in Hancock and
Adams Counties of another till sheet below the Illinoian and separated
from it by a black soil. This Kansan or some other pre-Illinoian till
sheet has been found in many places in Illinois (op. cit., pp. 107–118).
Animal remains are not likely to be inclosed in the materials of the
moraines or of the intermorainal till; but this is possible. A musk-ox
or a hairy mammoth might have died not far away from the foot of a
stationary or advancing glacier and its bones might have become
incorporated in the moraine. Furthermore, inasmuch as any glacial stage
began while the glacier was yet in the far north and ended only when it
got back there, many non-glacial deposits belonging to that glacial
stage were probably laid down south of it; and it would be difficult or
impossible to distinguish these from interglacial deposits. However, it
was these deposits which were laid down after the glacial ice had
withdrawn, whether glacial or interglacial, which are of more interest
to the palæontologist, because in them are to be found the fossil
remains of animals and plants.
The last of the interglacial stages, that which immediately preceded the
Wisconsin and followed the Iowan, is known as the Peorian. This takes
its name from a locality a few miles east of Peoria (Leverett, Monogr.
XXXVIII, p. 187). Here the Shelbyville till sheet is underlain by a bed
of fossiliferous loess from 8 to 12 feet in thickness. Beneath the loess
is fully 100 feet of Illinoian drift. This loess seemed to the
geologists who examined it to be a deposit of more recent date than the
Sangamon.
The Peorian interglacial stage and the preceding Iowan glacial stage
have received much attention within recent years. In 1917 (Geol. Surv.
Iowa, vol. XXVI, pp. 49–212), Alden and Leighton presented the results
of their studies on the Iowan drift and the loess associated with it. In
1918 (U. S. Geol. Surv., Prof. Pap. 106, pp. 1–356), Alden dealt with
the Quaternary geology of southeastern Wisconsin. The results of these
investigations have been to establish the fact that a sheet of till
intermediate between the Illinoian and the Wisconsin had been laid down,
that which had already been designated as the Iowan; furthermore, that
immediately following this there was deposited a covering of loess. It
was further concluded that this is the main loess deposit, much of what
has been regarded as Sangamon loess being really loess of a later stage,
the Peorian.
As no Iowan drift is known to be present in Illinois to separate the
loess of the Sangamon from the Peorian, it must be difficult, often
impossible in our present state of knowledge, to distinguish the one
from the other. The Sangamon loess was laid down probably long after the
Illinoian ice disappeared, so that there was time for the Illinoian
drift to become leached and otherwise modified and for the accumulation
of old soils and peat-beds.
On the other hand, the old soils of the Peorian stage are likely to
overlie the loess. Unfortunately, the desired indications of geological
age are not always present where bones and teeth are found; or, if
present, are not always observed. We must, therefore, make our
assignments of fossils to one stage or the other with great
circumspection or leave the decision in abeyance.
Reference has already been made to the presence of Kansan drift in
western Illinois and of black soils intervening between it and the
Illinoian. Such soils must be referred to the Yarmouth interglacial
stage. Whether or not still older glacial or interglacial deposits occur
in Illinois is problematic.
In Illinois any considerable number of species of fossil vertebrates are
rarely found together. The localities are widely scattered and a single
species or two in each is the rule (map 38). In later glacial deposits
around the south end of Lake Michigan have been discovered the dogfish
_Amiatus calvus_ and a sun-fish belonging to the genus _Lepomis_. Baker
(Univ. Ill. Bull. XVIII, p. 85) reported the humerus of the merganser,
_Mergus serrator_, from the same region. The ground-sloth _Megalonyx
jeffersonii_ (pp. 33–34) has been found at Urbana, Galena, and Alton.
The few horses are described on page 187. Peccaries have been found at
three localities (p. 218). For the specimens of deer that have come to
light, see page 229. A species of _Cervalces_ and the moose _Alces
americanus_ have been met with in Will County (p. 107). The reindeer has
been recognized from poor materials found at Alton. The prong-horn
_Antilocapra_ appears to have lived in the region of Galena, as shown by
Wisconsin specimens. The remarkable antelope _Taurotragus americanus_
has been found at Alton (p. 339). As to the musk-oxen and the bisons,
the reader may refer to pages 251, 259, 268; for the mastodons and
elephants, to pages 100, 140, 152, and 176.
Of the rodents, the muskrat has been found about Chicago; the pocket
gopher at Alton and Galena; the ground hog at the same places (p.
343). The beaver (p. 339) likewise occurs at Alton. The giant beaver,
_Castoroides ohioensis_, has been collected at four widely removed
places (p. 279). The rabbit, _Sylvilagus floridanus_, was included
among the animals found in the lead crevices of the region about
Galena, where also have been found an extinct species of raccoon,
_Procyon priscus_, what appears to be a large dog _Canis_ (or
_Ænocyon_) _mississippiensis_, the coyote, _Canis latrans_, and the
fox _Urocyon cinereoargenteus_. The bear, _Ursus americanus_, and the
common gray wolf, _Canis nubilus_, appear to have existed in the
middle Pleistocene at Alton.
A skull of _Felis couguar_, the yet existing panther or mountain lion,
has been found in Randolph County, in the bed of Kaskaskia River. It
probably belongs to the late Pleistocene.
A considerable fauna has been secured in the lead region about Galena,
in Illinois, Iowa, and Wisconsin. The collectors and describers of this
were not careful to designate the localities, and in some cases these
can not at present be determined. These collections are discussed on
page 343, in the account of the geology of Wisconsin.
An interesting list of Late Wisconsin mammals has been secured near
Whitewillow, Kendall County. From Dr. E. S. Riggs, of Field Museum of
Natural History, and from Netta C. Anderson’s list, the writer learns
that at least six skulls of the common mastodon, together with many
other parts of the skeleton, has been taken from a well 10 feet in
diameter (p. 109). Above, there were bones of bison (p. 269), deer (p.
229), and elk (p. 240). It is stated that a layer of these about 2 feet
thick was encountered at a depth of about 5 feet.
Mr. George Langford, of Joliet, states that he made a collection of
bones 15 miles west of Joliet and 5 miles west by north of Minooka. The
more exact locality he gave as township 35 north, range 8 east, and
probably section 27, on the farm of John Bamford. Apparently both Riggs
and Langford obtained their materials at the same spot. The latter has
sent the writer some bones from this place, including those of
_Cervalces_, _Alces americanus_, and a leg-bone of some undescribed
species of sheep or goat. He also reported the finding of the elk. For
other remarks see page 269. This locality is in the region mapped by
Leverett as having been occupied, after the retirement of the Wisconsin
glacial ice, by temporary lakes. The presence of the moose here seems to
indicate a climate somewhat severer than that now prevailing in that
region. Since the occupancy of the country by the European race the
moose has not been known to come further south than northern Wisconsin.
The list of species obtained is as follows: _Mammut americanum_, _Ovis_
sp. indet., _Odocoileus virginianus_, _Cervus canadensis_, _Alces
americanus_, _Cervalces roosevelti?_.
A brief description of the bone referred to _Ovis_ is presented. The
lower epiphysis is missing, but an allowance is made for this (fig. 13).
_Comparisons of the metatarsals of a sheep, of a goat, of Næmorhedus,
and of Orvis sp. from Whitewillow, in millimeters, together with
indices in one-hundredths of the length._
┌──────────────┬───────┬─────╥───────┬─────╥──────┬─────╥───────┬─────┐
│ Measurements │ │ ║ Capra │ ║ │ ║White- │ │
│ taken. │ Næmo- │Indi-║hircus │Indi-║ │Indi-║willow │Indi-│
│ │rhedus.│ces. ║155623.│ces. ║Sheep.│ces. ║animal.│ces. │
├──────────────┼───────┼─────╫───────┼─────╫──────┼─────╫───────┼─────┤
│Length on │ │ ║ │ ║ │ ║ │ │
│ outer border│ │ ║ │ ║ │ ║ │ │
│ of bone │ 170│ 100║ 120│ 100║ 152│ 100║ 185±│ 100│
│Side-to-side │ │ ║ │ ║ │ ║ │ │
│ width of │ │ ║ │ ║ │ ║ │ │
│ upper │ │ ║ │ ║ │ ║ │ │
│ articular │ │ ║ │ ║ │ ║ │ │
│ surface │ 36│ 21.2║ 23│ 19.2║ 23│ 15.1║ 37.5│ 20.3│
│Fore-and-aft │ │ ║ │ ║ │ ║ │ │
│ width of │ │ ║ │ ║ │ ║ │ │
│ upper │ │ ║ │ ║ │ ║ │ │
│ articular │ │ ║ │ ║ │ ║ │ │
│ surface │ 30.5│ 17.4║ 20│ 16.7║ 21│ 13.8║ 37.5│ 20.3│
│Side-to-side │ │ ║ │ ║ │ ║ │ │
│ width, at │ │ ║ │ ║ │ ║ │ │
│ middle of │ │ ║ │ ║ │ ║ │ │
│ length │ 23│ 13.5║ 15│ 12.5║ 14│ 9.2║ 19.0│ 10.3│
│Fore-and-aft │ │ ║ │ ║ │ ║ │ │
│ width at │ │ ║ │ ║ │ ║ │ │
│ middle of │ │ ║ │ ║ │ ║ │ │
│ length │ 17.5│ 10.3║ 11.5│ 9.1║ 13│ 8.6║ 20.0│ 10.8│
│Side-to-side │ │ ║ │ ║ │ ║ │ │
│ width at │ │ ║ │ ║ │ ║ │ │
│ lower end │ │ ║ │ ║ │ ║ │ │
│ just above │ │ ║ │ ║ │ ║ │ │
│ epiphysis │ 38│ 22.4║ 27│ 22.5║ 27│ 17.8║ 35.0│ 19.5│
│Side-to-side │ │ ║ │ ║ │ ║ │ │
│ width across│ │ ║ │ ║ │ ║ │ │
│ lower │ │ ║ │ ║ │ ║ │ │
│ articular │ │ ║ │ ║ │ ║ │ │
│ surface │ 41│ 24.1║ 27.2│ 22.5║ 25│ 16.4║ │ │
└──────────────┴───────┴─────╨───────┴─────╨──────┴─────╨───────┴─────┘
[Illustration:
FIG. 13.—Metatarsal of undetermined species of Ovis? From Kendall
County, Illinois.
]