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.

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).

From Alton, the U. S. National Museum has come into possession of a collection which furnishes 15 species of fossil mammals. This was made some time before 1883 by Hon. William McAdams, of Alton. It was briefly mentioned by him at the Minneapolis meeting of the American Association for the Advancement of Science in 1883 (Proceedings, vol. XXII, p. 268). Apparently the collection was secured for the U. S. Geological Survey by Professor O. C. Marsh and remained at Yale University until after his death. The species were described by the writer in 1920 (Proc. U. S. Nat. Mus., vol. LVIII, pp. 109–117). This collection seemed especially valuable because the species were found inclosed in supposed nodules of loess. In our country the loess has furnished few such remains. The following is the list of the species as determined. Those marked by a dagger are extinct.

• †Megalonyx jeffersonii (p. 33).
• †Equus sp. indet. (p. 187).
• †Platygonus cumberlandensis? (p. 219).
• †Sangamona fugitiva.
• †Cervalces roosevelti?.
• †Rangifer muscatinensis? (p. 246).
• †Taurotragus americanus.
• †Symbos cavifrons (p. 254).
• †Bison sp. indet. (p. 259).
• †Mammut americanum (p. 102).
• Castor canadensis.
• Marmota monax.
• †Castoroides ohioensis (p. 279).
• Geomys bursarius.
• Ursus americanus.

Of these 15 species at least two-thirds are now extinct. This large number might appear to indicate that the time of their existence was rather early in the Pleistocene. However, it is quite certain that the loess belongs somewhere about the middle of the Pleistocene; and there are no species that require an earlier date.

After the writer’s descriptions of the fossils had been published, an important paper on the geology of the locality was issued (Jour. Geol., vol. XXIX, 1921, pp. 505–514) by Professor Morris M. Leighton, who had been commissioned by the Illinois Geological Survey to visit and study the deposits involved. With the aid of Mr. John D. Adams, son of the collector of the mammalian fossils, Professor Leighton succeeded in finding the quarry in which most of the fossils had been collected.

At one quarry in Alton Professor Leighton obtained the following geological section, the description of which is here somewhat abridged:

The concretions which hold the mammalian fossils were found to lie between the upper surface of the till and the overlying loess; occasionally a concretion bears a drift pebble. The concretions have resulted from the lime which in solution was brought down from the loess and again precipitated so as to cement the loess materials around the fossils.

Professor Leighton was not able to determine definitely the ages of the till and of the two deposits of loess. As to the till, its geographic location suggested that it belonged to the Illinoian, but it had many of the characteristics of the Kansan. The latter is believed to be present at St. Louis and other localities not far away. Before the overlying reddish loess had been deposited the till had suffered weathering and erosion, indicating a considerable lapse of time had intervened. The lower reddish loess presented many evidences that it is a deposit distinct from the upper buff loess; and there seemed to be some indications of at least a short interval between them. Leighton’s conclusion was as follows:

If the drift is Kansan in age, the reddish loess may be Sangamon; if, on the other hand, the drift be Illinoian, the reddish loess probably is Peorian. It is unlike any Peorian loess of which the writer knows, but the color does not necessarily preclude that possibility.

As to the upper loess, Leighton thought it might be of early Peorian age, but possibly of early Wisconsin. However, his final conclusion was thus expressed:

“If the till proves to be Kansan in age, the weathering of the drift may be credited to the Yarmouth interglacial epoch, the mammalian fauna to late Illinoian or early Sangamon times, the reddish loess probably to the Sangamon, and the buff loess to the Iowan.... However this may be, the Illinoian and Sangamon epochs are post-mid-Pleistocene from the standpoint of duration of the Pleistocene and the fauna represented by the McAdams collection may be regarded as post-mid-Pleistocene.”

WISCONSIN.

The greater part of this State is covered by the drift-sheet which has derived its name from the State, but in the southwestern corner is a considerable tract which has never been subjected to glacial action. A small part of this area extends southward into Illinois and another part into northeastern Iowa. In Wisconsin it reaches eastward to Baraboo. East of this driftless area is a tract lying along the southern border of the State and reaching eastward about to 88° 40′ longitude, which is covered by the Illinoian drift.

The most detailed geological survey of any part of Wisconsin, so far as regards the Pleistocene, is that made by Dr. W. C. Alden, of the U. S. Geological Survey, of the area comprised between the boundary of the State on the south and 44 degrees of latitude on the north and between Lake Michigan on the east and 90 degrees of longitude on the west. On the western side it joins the Mineral Point Quadrangle, to be mentioned further along. There is, therefore, a wide strip surveyed across the whole State. The area treated by Alden is, of course, nearly entirely covered by Wisconsin drift. In the southwestern corner a considerable part of the driftless region is included. East of this, as already stated, is a tract which the Wisconsin ice-sheet did not reach and which shows Illinoian ground moraine and some terminal moraines of Illinoian drift. This narrows as it approaches its eastward limit.

Alden (p. 166) informs us that at no place in the area subjected to vigorous glaciation by the Wisconsin ice-sheet had soils or vegetal deposits been found between the Wisconsin drift and the earlier drifts. At several places, however, deposits have been discovered which probably belong to earlier glacial stages. Just outside the area mapped by Alden, in Calumet and Outagamie Counties, Lawson (Bull. Wis. Nat. Hist. Soc., vol. II, pp. 170–173) has recorded the discovery of much wood and other vegetable matter. Baker (“Life of the Pleistocene,” p. 317) has referred the deposits to the Sangamon. These interglacial deposits of uncertain age need not be here noted further. In this Wisconsin area some remains of mastodons and elephants have been met with, but all are relics of a time after the partial or complete recession of the Wisconsin glacier. Remains of two individuals of Elephas primigenius have been found in Milwaukee (p. 143). It is evident that they lived there after the withdrawal of the Wisconsin ice-sheet. One of these was buried beneath peat and clay at a depth of 10 feet or more and at a level of about 100 feet above the present level of Lake Michigan.

At Dover, in Racine County, in 1878, a proboscidean tusk and some bones were found in a peat-bog. They have been identified as those of a mastodon, but of this one can not be certain. The age of the deposits is that of the Late Wisconsin stage, after the withdrawal from that vicinity of the ice, but how long after one can not say. The Milwaukee Public Museum has a tooth of a mastodon (p. 111), labeled as found at Waukesha. Its geological age is that of the other remains here referred to. In the collection of the University of Wisconsin is a large vertebra of a proboscidean which was found in Lake Monona. Its time of burial must have been late Wisconsin. Inasmuch as no remains of vertebrate animals have yet been found in Wisconsin, in the area covered by the Illinoian drift, it is not necessary to dwell on this region. It is not certain that there is beneath it a still older drift; but there are, according to Alden, some indications of such deposits.

For a knowledge of the driftless area, first of all, may be consulted the report made by Chamberlin and Salisbury in 1885 (6th Ann. Rep. U. S. Geol. Surv., pp. 199–322, with plates). Alden’s work above referred to maps a part of the region. Grant and Burchard have studied the geology of the Lancaster and Mineral Point Quadrangles (Folio U. S. Geol. Surv. 145). Their text-figure 1 is here reproduced, inasmuch as it shows the relation of the region to the surrounding glaciated areas (fig. 14). The topographical map of Folio 145 and that of Chamberlin and Salisbury will show the uneven character of the surface. This has resulted from the erosion undergone during the whole of the Pleistocene. Much of the area is covered with a coating of loess. Along Mississippi River this may be as much as 10 feet thick, but at a distance of from 30 to 40 miles it becomes reduced to a few inches. Considering this erosion, one might conclude that few vertebrate remains would be preserved; nevertheless they are not wholly missing.

In 1862 (Geol. Surv. Wisconsin, vol. I, p. 136), J. D. Whitney stated that he had found in a crevice at Blue Mounds, Wisconsin, remains of the mastodon (p. 111), a peccary (p. 219), bones and teeth of a buffalo (p. 270), and a wolf which he referred with doubt to Canis latrans. The depth was uncertain, but it may have been as much as 40 feet. The fossils were embedded in reddish clayey loam, the usual crevice earth. On page 422 of the same volume, Jeffries Wyman referred the wolf remains to two distinct species, Canis occidentalis and C. latrans. In 1876, Dr. J. A. Allen (Amer. Jour. Sci., ser. 3, vol. XI, pp. 47–49) described from the same lot of bones the species C. mississippiensis. This apparently did not include jaws and teeth that Wyman had referred to C. occidentalis. In Wyman’s paper, on page 422, he assigned three teeth to Dicotyles torquatus, an existing peccary, without stating that it had been found at Blue Mounds. In 1869 (Jour. Acad. Nat. Sci. Phila., ser. 2, vol. VII, p. 384), Leidy referred this peccary to his Dicotyles lenis, an extinct species. Inasmuch as the peccaries found at Galena were identified by Leidy (Whitney, vol. cit., p. 424) as Platygonus compressus (p. 218), it appears pretty certain the Dicotyles lenis (Tagassu lenis) was among the fossils collected at Blue Mounds (p. 219). It must, however, be kept in mind that Whitney, on page 35, stated that he had collected bones and teeth of the same animal near Dubuque, Iowa. Allen regarded the buffalo as belonging to an extinct species; but it is really undeterminable. Accordingly there may be credited to this locality the following species: Tagassu lenis, Bison sp. indet., Mammut americanum, Canis nubilus (C. occidentalis), C. mississippiensis, C. latrans.

In Whitney’s report, on page 133, he announced the finding of a large quantity of bones of mastodons at Sinsinawa Mound (p. 111), but he did not know at what depth they occurred. It seems probable that they had been met with in one or more crevices.

It seems probable that the animals found in crevices in the lead region of Wisconsin, Illinois, and Iowa belong approximately to one geological stage of the Pleistocene. The following appears to include all known to have occurred in such situations:

• Megalonyx jeffersonii?.
• Platygonus compressus.
• Tagassu lenis.
• Odocoileus virginianus?.
• Cervus canadensis.
• C. whitneyi.
• Antilocapra americana.
• Bison sp. indet.
• Mammut americanum.
• Marmota monax.
• Microtus sp. indet.
• Geomys bursarius.
• Sylvilagus floridanus? (Lepus sylvaticus).
• Anomodon snyderi.
• Procyon priscus.
• Canis nubilus (C. occidentalis).
• C. mississippiensis.
• C. latrans.

The writer was at one time inclined to believe that these animals belonged to the time succeeding the withdrawal of the Wisconsin ice-sheet. Baker (“Life of the Pleistocene,” p. 353) thinks that they belong probably to the Peorian, inasmuch as the region is covered by Iowan loess, beneath which many of the bones have been found. It is quite probable that those crevices were open during at least some part of the Pleistocene and that animal remains collected in them. The fossils are reported as being sometimes inclosed in a matrix of cave or fissure materials which are cemented together by iron. The considerable number of extinct species, certainly 7 out of about 18, makes it probable that the fauna is not so recent as the Late Wisconsin.

It appears to be determined that the Iowan loess was formed immediately after the retirement of the Iowan ice-sheet. It might, therefore, be a question whether all of these animals might have got into those crevices in time to be covered in by the loess. On the other hand, the Illinoian drift was, for a long time, exposed to weathering and erosion before the Iowan drift and loess were laid down. Also, the Sangamon interval was probably much longer than the Peorian, so that the chances for the accumulation of the fossils were greater. It seems, however, that we can only say that the fossils are post-Illinoian and probably pre-Wisconsin.

Besides the vertebrate fossils referred to above, a few others, especially mastodons (pp. 110, 111), have been found at other places, but so little is known of the conditions of their interment that they furnish little geological information.

A very interesting region is found in the western part of the State, in Dunn and Pepin Counties. This has been examined with great care by Dr. Samuel Weidman, State geologist of Wisconsin. About Menomonie there are several brickyards, whose excavations furnish opportunities for studying the formations at that point. Sections of one of these brickyards are described and illustrated by Dr. E. R. Buckley, in Bulletin VII, part 1 (1901), page 194, plate XXXVII. A section and brief description is found also in a paper by Dr. Hussakof (Jour. Geol., vol. XXIV, p. 688). In that region are found outwash gravels which have been definitely correlated by Weidman with Iowan drift. In some places this is overlain by loess. These gravels vary from 10 to 20 feet in thickness at Menomonie. Beneath the gravels are found lacustrine clays varying in thickness from 20 to 40 and even 60 feet. These are stratified and consist of layers from 1 to 12 inches in thickness, with intervening thin layers of sand. Toward the bottom the sand increases in amount. Beneath the clay-bearing formation is a bed of sand attaining a maximum thickness of about 150 feet. This is underlain by coarse sand and gravel. The lacustrine clays and the underlying sands and gravels are included by Weidman in his Menomonie formation, and this is believed by him to be of Sangamon interglacial age. In northwestern Wisconsin are found other glacial deposits believed to belong to the Illinoian drift epoch.

In the lacustrine clay at Menomonie have been found remains of the great lake trout, Cristivomer namaycush (Hussakof, as cited above), of a deer (p. 230), a caribou (p. 247), and probably a mastodon. The deer is represented by a single vertebra, identified by Dr. W. D. Matthew. The supposed mastodon is indicated by the distal end of the right femur, the caribou by an antler of a young and probably female individual and by the shaft of a large individual.

At Woodville, in St. Croix County, about 20 miles west of Menomonie, has been found a forest bed regarded as belonging to the Aftonian. This was described by Arthur Koehler (Amer. Forestry, vol. XXVI, Feb. 1916, p. 92, 3 figs.). Wood was found that was identified as that of spruce.

In 1913 (Science, n. s., vol. XXXVII, p. 457), in a brief abstract, Weidman reported that in Wisconsin he recognized drift deposits of Wisconsin, Iowan, and Kansan ages and another still older. No localities were mentioned, but his statements were doubtless based mostly on his work in the western part of the State. The loess was found to be laid down after the Iowan and before the Wisconsin. Interglacial deposits were found between the Kansan and the Iowan.

In 1905 (Jour. Geol., vol. VIII, pp. 238–256) and in 1910 (Jour. Geol. vol. XVIII, pp. 542–548), Dr. R. L. Chamberlain presented the results of his investigations on the “Pleistocene Geology of the St. Croix Region in Western Wisconsin.” His conclusion (p. 548) was that in that part of the State there were present (1) a surface mantle of gray Wisconsin drift deposited by a glacier from the Keewatin center; (2) red Wisconsin drift deposited by a glacier coming from the Labrador center; (3) a red drift left by an ice invasion from the Labrador center, its age consistent with Illinoian; (4) a grayish-black till that had come from the Keewatin center and whose age was probably Kansan.

MARYLAND AND DISTRICT OF COLUMBIA.

For obvious reasons the Pleistocene geology of the District of Columbia is considered in connection with that of Maryland. This region is of especial interest, because of the long time and the care which has been bestowed on it by geologists and because the conclusions reached have been applied to the geological study of States both toward the north and toward the south.

The most complete exposition of the Pleistocene geology of the region is to be found in the volume of the Maryland Geological Survey entitled “Pliocene and Pleistocene,” published in 1906. The geological treatise itself was written by George Burbank Shattuck and is illustrated by many maps and text-figures. Included in this is a bibliography of the subject which occupies 17 pages. There is a chapter by W. B. Clark, Arthur Hollick, and F. A. Lucas, on the interpretation of the palæontological criteria; another by F. A. Lucas on the mastodons and the elephants. The Pleistocene mollusks found in the State, 40 species, were described and figured by W. B. Clark; while the plants, also nearly 40 in number, were described and figured by Arthur Hollick.

The history of the development of our present knowledge of the geology of Maryland and the classification of its formations up to 1906 is given by Shattuck in the volume just cited (pp. 25–40). This geologist recognized in the superficial deposits of the State five formations (fig. 15). These are, beginning with the oldest, Lafayette, Sunderland, Wicomico, Talbot, and Recent.