For a knowledge of the Pleistocene of Canada, the student ought first to read Dr. J. W. Dawson’s “Canadian Ice Age,” published in 1894. In this will be found references to the earlier literature of the subject. For the results of more recent studies the reports of the Canadian Geological Survey are to be consulted, as well as papers published in the scientific journals. For the more important of these papers the reader may consult the list published by Dr. H. L. Fairchild in 1918 (Bull. Geol. Soc. Amer., vol. XXIX, pp. 229).
To state the matter briefly, one may say that almost everywhere in Ontario are deposits of glacial drift of Wisconsin age. In a few localities have been discovered beds which belong to earlier glacial and interglacial epochs. On the other hand, around Hudson Bay, around the Gulf of St. Lawrence, along St. Lawrence and Ottawa Rivers, and the Bay of Fundy are marine deposits, laid down after the Wisconsin ice had retired from those localities and while the region which had been occupied by this ice-sheet was depressed so much that the sea could enter the basins named.
The most interesting locality in Canada for the student of vertebrate palæontology is doubtless Toronto, because of the presence there of Pleistocene deposits belonging to more than one stage, and because of the discovery of several species of extinct vertebrates and of many mollusks, insects, and plants. For an understanding of the geology of the region Coleman’s papers must be studied, as well as those of authors cited by him. On the interglacial deposits three of Coleman’s papers may be especially cited (Jour. Geol., vol. IX, 1901, pp. 285–310; 10th Internat. Cong. Geol., 1906, Mexico, pp. 1237–1258; Bull. Geol. Soc. Amer., vol. XXVI, 1915, pp. 243–254).
According to Coleman’s figure 1 of the first paper cited, the known interglacial deposits in that region extend from the mouth of Humber River eastward beyond the mouth of Rouge River, a distance of about 22 miles, and away from the lake a distance of about 8 miles. Deposits have been found even 14 miles north of Toronto (Coleman, 1915, p. 246). Coleman’s sketch map of the region, taken from his paper of 1901, is here reproduced (fig. 3).
According to Coleman (paper of 1915, p. 243) there are known at Toronto five well-defined sheets of boulder clay, with four sheets of interglacial sand and clay separating them. So far as the writer knows, only the lowest of these beds have been described with any particularity. These lowest beds constitute the Toronto formation, and it is these which have furnished nearly all the fossil animals and plants discovered in that region. This Toronto formation is divisible into two portions, and these have been designated as the Don beds and the Scarboro beds. They are regarded as having been deposited in the valley of an ancient river running from Georgian Bay to Scarboro. Of these the Don beds are the older. Sections of these are found in Toronto and outside, especially along Don River. They have been laid down usually on a boulder clay, 1 to 9 feet thick, which itself reposes on Hudson River shales. At one point along the Don an interglacial river had cut through both the boulder clay and the shale to a depth of 16 feet. The Don deposits consist of varying layers of sands, gravels, and clays. At one point the section obtained amounted to about 27 feet; but this, combined with another, made up about 44 feet. At one place trunks, 12 or 15 feet long, of trees have been found, which were flattened into the surface of the boulder till; also shells of unios, which are embedded in clay close to the boulder till.
Fig. 3.—Region about Toronto, Ontario, showing location of Toronto and Scarboro Heights Pleistocene beds. From Coleman.
In 1913 (Ontario Bur. Mines. Guide Book No. 6, pp. 15–18), Professor Coleman presented a list of the species found in the Don beds. Of the plants 32 species of trees had been secured, among them the pawpaw, the red cedar, and the osage orange; 41 species of fresh-water mollusks were listed, of which 12 were Unionidæ.
As bearing on the climate, it may be said that there are 12 species of the genus Unio listed, of which 4 species are now known only from localities south of the St. Lawrence drainage; while 3 other species live in Lake Erie, but not in Lake Ontario. The plants are mostly trees; and several species, as the osage orange and the pawpaw, are now found only considerably farther south. One species of maple no longer exists. Penhallow gave it as his opinion that the flora points conclusively to the existence of climatic conditions of a character more nearly like that of the middle United States to-day. The unios now missing from that region give evidence to the same fact. For these reasons the Don deposits are spoken of as the warm-climate beds.
The Scarboro beds are finely displayed at Scarboro heights, a few miles east of Toronto. The thickness of the clay here amounts to about 94 feet. In these deposits have been found possibly mammoth or mastodon and caribou, but there is some uncertainty about these. Only 14 species of plants have been secured and these are trees; but apparently no mollusks have been reported. As an offset there are great numbers of beetles. Of these there have been described 72 species, and all are extinct except 2.
The trees, according to Penhallow, indicate a climate somewhat cooler than that now prevailing in that region. The same conclusion was reached by Scudder from his study of the insects. In his paper of 1901, Coleman took the view that the Toronto formation had been laid down in the interval between the Iowan and the Wisconsin glacial stages, that is, during what is now known as the Peorian. In the address of 1906, page 44, he appears to have been inclined to accept Leverett’s view that at least the Don beds belonged to the Sangamon stage. By 1915 (paper cited, p. 252) he had about concluded that the Toronto beds were as old as the Aftonian stage.
Dr. G. F. Wright, in 1912 (Bull. Geol. Soc. Amer., vol. XXV, pp. 205–218), accounted for the deposits and fossil animals and plants found at Toronto in a different way. At a certain time in the Pleistocene the region about Toronto was occupied by some species of animals and plants now found only considerably further south. An ice-sheet from the Keewatin center extended thither and laid down the Don beds. Later the Labrador glacier pushed into that region and deposited the Scarboro beds. According to this view the whole succession of events would be much shortened.
The writer is disposed to accept Leverett’s estimate of the geological position of the interglacial beds at Toronto. The presence there of Elephas primigenius, Mammut americanum, and the probable Ursus americanus hardly counts in the determination of the geological age, for all these animals appear to have continued on from at least the Aftonian interglacial to the close of the Wisconsin. There are no specimens that show that either Rangifer or Cervalces existed during the Aftonian, although one can hardly doubt that they did then exist. In order to show that the Toronto formation belongs to the Aftonian, it would be necessary to produce satisfactory stratigraphical evidence or to find there genera and species of mammals which characterize the Aftonian, such as camels, Elephas imperator, and those horses which belong to the early Pleistocene. If the deposits belong to the Sangamon stage, such horses as Equus complicatus and E. leidyi ought in time to be discovered there.
Coleman has discussed the interglacial beds that occur elsewhere in Canada (10th Internat. Geol. Congr. 1906, Mexico, pp. 1237–1258; Bull. Geol. Soc. Amer., vol. XXVI, 1915, pp. 243–254). He refers to Chalmers’s account of interglacial deposits along Lake Erie; but so far as the writer has been able to determine, most of the deposits referred to are of Late Wisconsin age. However, as he says, Spencer found interglacial materials near Niagara Falls. Other beds have been discovered along Moose River, south of James Bay; but their geological position has not been definitely determined, and the fossils discovered there, mostly proboscideans, are not referred with certainty to the interglacial deposits.
Most of the vertebrate fossils found in Ontario, excepting many of those found at Toronto, belong to the Late Wisconsin stage; and in studying their geological relations one must, as in the States of New York, Ohio, Indiana, and Michigan, take into consideration the history of the Great Lakes after the Wisconsin ice-sheet began to retire. According to Leverett and Taylor’s maps (Monogr. LIII, U. S. Geol. Surv., plate XIV), as early as the time when the glacial ice had just begun to withdraw from Lakes Michigan and Erie, a considerable area of land had become cleared of ice in the peninsula bounded by Georgian Bay, Lakes Huron, Erie, and Ontario. We can hardly suppose, however, that any mastodons or any elephants, except possibly Elephas primigenius, could have made their way to that area. Even the last-mentioned species would have had to travel over many miles of glacial ice. Conditions were hardly more favorable when Lake Whittlesey had come into existence (op. cit., plate XVI). At a later stage (op. cit., plate XVII) the ice-free parts of the peninsula could have been reached only by crossing the lakes or over wide stretches of glacier. It is possible that some of the mastodons and elephants that have been found had crossed over into Ontario at about the stage represented by plate XIX of the work cited, but it is more probable that they lived there at a later time.
Brief mention is here made of the fossil vertebrates found in Ontario and their localities. More detailed statements will be found on the pages cited.
Beginning in the west, a mastodon has been found at Blythewood, Essex County (p. 45). In Elgin County a mastodon has been met with at St. Thomas (p. 45), and a mastodon (p. 45) and an undetermined species of elephant at Highgate (p. 45). A little farther back from the lake, at London, Middlesex County, has been found a mastodon (p. 45). At Marburg, not far from the shore of Lake Erie, Dr. H. M. Ami exhumed a mastodon (p. 45). The writer has not learned how this locality is related to the ancient beaches. At Dunnville, Haldimand County, a mastodon has been secured (p. 46). It could hardly have lived there before the lake had assumed nearly its present level. The same remark will apply to the time when the mastodon (p. 46), Elephas columbi (p. 147), and possibly E. primigenius (p. 166) lived at St. Catharines. From Hamilton, at the extreme western end of Lake Ontario, have been described remains of Elephas columbi (p. 147), E. sp. indet. (p. 166), elk, Cervus canadensis (p. 235), and the beaver. Elephas primigenius has been found at Toronto, (p. 130); also Cervalces, a bison (p. 256), and a reindeer (p. 244). The same elephant has been discovered at Amaranth, in Dufferin County (p. 130). The elk, Cervus canadensis, has been reported from Strathroy, Middlesex County, and Kingston, Frontenac County (p. 235). At Smith’s Falls, Lanark County, the humpback whale, Megaptera boöps, has been discovered (p. 17). White whales, Delphinapterus leucas and D. vermontanus, have been found at Pakenham, Lanark County (p. 17), at Cornwall, Stormont County (p. 18), Nepean Township (p. 17), Ottawa East, Carleton County, and Williamston, Glengarry County (p. 18). At Ottawa has been discovered an assemblage of species, as listed on page 287.
The geology of the Hamilton locality has been described by Logan (Geol. Canada, 1863, p. 914), by Spencer (Canad. Naturalist, vol. X, 1883, pp. 222–230, 306–308), and by Coleman (Bull. Geol. Soc. Amer., vol. XV, 1904, p. 351). The remains mentioned were found in deposits forming what is called Burlington Heights. Here Dundas Valley opens into the extreme western end of Lake Ontario. The valley is about a half mile wide. Across this had been formed a bar, interrupted only at its northern end, with a height of 108 feet above the level of the lake and a width varying from a few hundred yards to less than a half mile. Its height is almost that of the Iroquois beach found on the south shore of the lake and continuing on the northern shore. Many years ago a canal was cut through the narrowest part of the bar, and it was in the construction of this that the elephant (p. 166), elk (p. 235), and beaver bones were found. It is evident that the bones were deposited there while the bar was being built and at a time when it lacked 38 feet of being as high as it now is. The elephant jaw is in good condition, and this indicates that the animal died near the spot.
Coleman (op. cit., p. 352) stated that afterwards a railroad cut had been made across the southern end of the bar, exposing 30 feet of coarse stratified gravel, followed below by 2 feet of brown clay (evidently an old soil) and 8 feet of blue till. In the old soil were found quantities of decayed wood, as well as bones of mammoth and other animals. About a mile farther west, pits were opened for clay, sand, and gravel. Coleman gives the following geological section at this place. The column at the right gives the heights above the lake level.
| feet. | feet. | |
|---|---|---|
| Clay making red brick | 6 | 78 |
| Gravel | 30 | 72 |
| White sand | 5 | 42 |
| Hard pan | 4 | 37 |
| White sand with mammoth tusks and bones | 33 | |
| Covered to level of the bay | 0 |
The mammoth tusks and bones were not water-worn. It will be observed that they were found 83 feet below the top of the Iroquois beach (116 feet above the present lake), while the jaw was only about 45 feet below the beach. Both Coleman, as cited, and Fairchild (Bull. Geol. Soc. Amer., vol. XXVII, p. 247) regard the formation of the bar at Hamilton as showing that during Iroquois times the lake became flooded to a height of about 82 feet.
Besides the interglacial species found at Toronto, which have already been mentioned, there may be noted a tooth of Elephas primigenius (p. 130), a cast of which was reported by Winchell. Whether this was derived from interglacial or late Wisconsin beds is not known. Coleman, as elsewhere cited, reported the finding of remains of one of the elephants on the Iroquois beach. On the same beach have been collected antlers of reindeer (p. 244). These animals must have lived there not earlier than the time when that beach was forming, perhaps later.
Fig. 4.—Eastern Ontario, showing limit of fresh-water beaches and marine fossils. Redrawn from Coleman.
In a buried gorge extending in a northwestern direction from the whirlpool at Niagara to the Niagara escarpment, Dr. J. W. Spencer (Bull. Geol. Amer., vol. XXI, p. 433) has discovered what he regards as deposits equivalent to the Toronto formation, while older glacial and interglacial beds are found below and more recent ones above. No fossils were met with except wood. At Amaranth have been secured considerable parts of a skeleton of Elephas primigenius (p. 130). This elephant must have existed rather late in the Wisconsin stage. About Kingston in Frontenac County, at two places, have been secured remains of the elk (p. 235), but lack of details as to places and conditions precludes certainty as to their geological age. The fact that they were found in shell marl is favorable to the idea that they belonged to the Pleistocene. Here may be mentioned again the bison horn of uncertain geological age which was found on the north shore of Nipissing Lake (p. 266). In Algoma County, on the banks of Moose River, was found a part of a skull of a mastodon, but there is uncertainty whether it had been buried in interglacial deposits or in marine Champlain beds. The region in the extreme eastern end of Ontario is interesting because it furnishes a considerable fauna belonging to the Champlain stage. During the last glacial stage the region on which the Wisconsin ice-sheet was resting became depressed to such an extent that when this ice retreated beyond the St. Lawrence River, marine waters occupied the basin nearly to the eastern end of Lake Ontario and Ottawa River as far as Lake Coulonge. Coleman’s figure of the region (Bull. Geol. Soc. Amer., vol. XII, pp. 129–146, fig. 1) is here reproduced (fig. 4) to show the western limits of the marine waters, so far as known, and the corresponding fresh-water beach along the north shore of Lake Ontario. Figure 5 from Coleman shows how the Champlain Sea was limited on the south. Marine fossils, especially mollusks, have been found along the upper St. Lawrence as far as Brockville, Quebec, and on the opposite side of the river, in New York. On Coleman’s map the present elevations of the old beaches at important localities are marked, that at Ottawa having an elevation of 450 feet and at Coulonge 370 feet. According to Johnston, who has described the Pleistocene geology in the vicinity of Ottawa (Mem. 101, Canad. Dept. Mines, 1917), there is a point about 8 miles northwest of the city where a marine terrace is found at a height of 690 feet above sea-level. The marine beds at Ottawa are divided into the Leda clays at the base and Saxicava sands above. The former have a maximum thickness of about 200 feet, the Saxicava sands, a thickness of about 40 feet. The fossils occur mostly in the Leda clays. In 1897, Dr. H. M. Ami (Ottawa Naturalist, vol. XI, pp. 20–26), and again in 1901 (Geol. Surv. Ann. Rep., XII, G, pp. 51–56), published lists of the fossils found in the Ottawa Valley, nearly all of them in the vicinity of Ottawa. There were listed 26 species of plants, about 13 species of marine mollusks, and the following vertebrates:
Fig. 5.—South shore-line of ancient Champlain sea. Redrawn from Coleman.
The aquatic forms are all species existing in the Gulf of St. Lawrence and along the northern Atlantic coast. The chipmunk lives at Ottawa. Specimens of feathers of birds also have been found in nodules, but the species have not been determined. The remains of the chipmunk were probably washed in by some fresh-water stream.
According to Johnston’s paper just cited, there are deposits of glacial drift underlying the marine Champlain beds, but they have furnished no fossils. The marine deposits extend up the Ottawa Valley at least as far as Coulonge Lake, and here has been found Mallotus villosus. At Welshe’s, 3 miles north of Smith’s Falls, Lanark County, have been found some remains of the humpback whale, Megaptera boöps (Dawson, Amer. Jour. Sci., vol. XXV, 1883, p. 200). It was met with (p. 17) at an elevation of 440 feet above present sea-level. It appears to have been left there during the time when the Saxacava sands and gravels were being laid down (Coleman, Bull. Geol. Soc. Amer., vol. XII, p. 133).
The Pleistocene of Quebec was described by Logan in 1863 (Geol. Canada, pp. 917–926) and by J. W. Dawson, 1894, in his “Canadian Ice Age.” Dawson divided the epoch, as represented in Canada, into the early Pleistocene, the mid-Pleistocene, and the later Pleistocene. He did not accept the glacial theory as it is now understood, admitting only great local glaciers. His early Pleistocene deposits embraced the great bulk of the boulder clays. His mid-Pleistocene represents an interglacial period, during which were deposited the marine Leda clays, Saxicava sands, and their fresh-water equivalents. The climate was supposed to be milder than at present. During the later Pleistocene there was to some extent a recurrence of local glaciation and of deposition of boulder clay. This stage was followed, according to Dawson, by the Early Modern, which he regarded as the age of the mammoth and mastodon.
Mr. J. Stansfield has described with some detail the Pleistocene and Recent deposits of the island of Montreal (Mem. 73, Geol. Surv. Canada, 1915). The boulder clay is of variable thickness and does not appear to be divisible into beds of different epochs. The Leda and Saxicava deposits are present. When the latter were laid down the region about Montreal was depressed about 600 feet below its present elevation. This has been confirmed by Goldthwait (Summary Rep. for 1913, p. 211). Later it began to rise; and Stansfield thinks that when the elevation had reached about 100 feet less than that of the present the water of the St. Lawrence at that point had become fresh. He found some apparent evidences of a recurrence of glaciation after the Champlain stage, but, on the whole, left the question undecided. He published a list of about 85 species of marine invertebrate fossils, collected from the Leda clay about Montreal, and 22 species obtained from the Saxicava sands. Besides the invertebrates secured from the Leda clays at that place, there are two vertebrates, Phoca grœnlandica (p. 22) and Delphinapterus leucas, or D. vermontana (p. 18). At Rivière du Loup, in Temiscouata County, whale remains were reported in 1894 (p. 18), which were thought to belong to Delphinapterus leucas. At Metis, Rimouski County, a jawbone of a whale has been discovered in the shelly marl of the lower terrace (p. 19); whether or not it belonged to Megaptera boöps is not certain. The specimen of the former species was described by Leidy in 1856.
According to Logan’s report of 1863 (Geol. Canada, p. 920), the single bone was found in a brickyard. At the same place was found some vertebræ of the whale. At Bic, Rimouski County, has been found a nearly complete skeleton of a walrus, at an elevation of more than 100 feet (p. 21). Dawson (Canadian Record Sci., 1895, vol. VI, p. 352) described a nearly complete skeleton of the whale which had been found at Montreal in the Leda clay, 22 feet below the surface. This Leda clay was supposed by Dawson to have been deposited at a depth of from 50 to 80 fathoms, which depth, he said, corresponded approximately to the marine shore-lines at Montreal at an elevation of about 470 feet above sea-level, and to the sea-beach at Smith’s Falls, above referred to. Hence at the time that the whale was buried the mountain at Montreal was only a rocky islet in the sea which prevailed then over the region from the Laurentian hills on the north to the highlands of Quebec, south of the St. Lawrence.
At Tétreauville, in Ottawa County, on Ottawa River, have been found some bones, supposed to belong to the harbor seal, Phoca vitulina.
All three of these regions were involved in the glaciation of the Wisconsin stage. According to Goldthwait (Summary Rep. for 1913, pp. 244–250), New Brunswick was the center from which the ice flowed out over the other two lands. From this center it moved southward over the western end of Nova Scotia, more and more southeastward over the rest of the peninsula, while over Cape Breton Island the direction was eastward and northeastward. Some indications were observed of an earlier glaciation. As regards post-glacial submergence, Goldthwait found that at St. John, New Brunswick, this had amounted to about 190 feet, while on Cape Breton Island no signs of any submergence were found. Robert Chalmers had arrived at similar conclusions; and these agree well with the theoretical isobases drawn by Taylor for that region (Monogr. U. S. Geol. Surv. LIII, 1915, p. 503). G. F. Matthew in 1879 (Geol. Surv. Canada, Rep. for 1877–78, EE, pp. 1–36) described the geology of southern New Brunswick. Few fossil vertebrates of Pleistocene age have been discovered in these countries. On Cape Breton Island mastodon remains have been found in two places, Middle River and Baddeck (p. 46). As long ago as 1874 remains supposed to belong to Delphinapterus were found near the mouth of the Jaquet River, in the northernmost part of New Brunswick; but Professor G. H. Perkins has shown that the animal was probably the narwhal, Monodon monoceros. The discovery is discussed here on page 19. At the southern extremity of New Brunswick, along Mace’s Bay, Charlotte County, a jaw supposed to belong to a species of Delphinapterus was found, which had been buried in the Leda clay (p. 19). Near Fairville, at the mouth of St. John River, there has been discovered some bones of the seal Phoca grœnlandica (p. 21). In the Academy of Sciences at Philadelphia is a skull of a walrus (p. 21) found apparently in the water near Sable Island about 50 years ago. It is not certain that it is a Pleistocene fossil.
Inasmuch as relatively few vertebrates belonging to the Pleistocene have been discovered in the New England States, it will not be necessary to enter into details regarding the geology of the glacial period in this region. Nevertheless, the subject is one of great interest and one which has engaged the attention of many geologists. For those who wish to enter on the study, the writer recommends first a paper written in 1906 (Bull. Geol. Soc. Amer., vol. XVIII, pp. 505–556) by Frederick G. Clapp, entitled “Complexity of the Glacial Period in Northeastern New England,” which gives a brief history of the development of the idea that in the region mentioned there are evidences of more than one glacial and of more than one interglacial stage. There are also citations of the principal papers written on the subject. Among the writers cited are Shaler, Woodworth, Fuller, Upham, Stone, and Tarr. Clapp concluded that New England had been invaded by at least three ice-sheets and that these invasions had been separated by two interglacial intervals of long duration. On account of the greater thickness of the drift and because of fewer favorable exposures, due to the rocky nature of the coast and other causes, many difficulties are encountered in studying the deposits. He regarded absolute correlations as not yet possible. The last glaciation he accepted as corresponding closely with the Wisconsin, as displayed in States further west. What is known as Montauk drift, forming a part of the Gay Head interval of Woodworth, appeared to Clapp to correspond possibly to the Illinoian. Still older drifts would seem to have their place nearer the pre-Kansan (Nebraskan) than to the Kansan. What have been called “Leda clays” are found from Boston north into the St. Lawrence Valley. Clapp divides them into the “high-level” and the “low-level” clays. The former are the older and regarded as being about the equivalent to the Iowan stage. The “low-level clays” are referred to the Wisconsin stage. Another body of clays named by Fuller (Bull. Geol. Soc. Amer., vol. XVI, p. 375) the Gardiner clays, from their type locality, Gardiner Island, near the east end of Long Island, lies beneath the Montauk till and has been referred by Fuller to the Yarmouth interglacial.
In his paper cited Clapp presents (pp. 520–523) a list of the fossils, mostly mollusks, which have been collected in the Pleistocene deposits from New Brunswick to New York.
Along the New England coast are evidences of uplift which followed the retirement of the Wisconsin ice. Katz (Jour. Washington Acad. Sci., vol. VIII, 1918, p. 410) reported elevations of 155 feet at Stratham, New Hampshire, and 300 feet at Pawnal, Maine. Fairchild (Bull. Geol. Soc. Amer., vol. XXIX, p. 214) records the elevations at various localities in Maine.
A brief interesting account of the Pleistocene epoch as recorded in Massachusetts and Rhode Island may be found in an article by B. K. Emerson (Bull. U. S. Geol. Surv., No. 597, pp. 134–149). It deals in part with the geology of the valley of the Connecticut River.
Goldthwait (Appalachia, vol. XIII, pp. 1–23) and Foshay (Amer. Jour. Sci., ser. 4, vol. XXXVIII, pp. 345–348) have found evidences of an early Pleistocene glaciation in the White Mountains of New Hampshire.
Vermont is interesting especially on account of the Pleistocene history of Lake Champlain. This history has been recently discussed by Professor H. L. Fairchild (Rep. State Geologist Vermont, vol. X, 1916, pp. 1–41, with maps and views), who presents (pp. 40–411) a list, 37 in number, of the more important papers relating to the subject.
While the Wisconsin ice-sheet was resting upon Canada and the northern part of the United States, the land thus occupied, and probably a considerable area beyond the ice, became depressed. The valleys of the St. Lawrence, the Ottawa, the Hudson, and the Connecticut had been pressed down to such an extent that, as the ice-sheet retired these valleys became filled with water standing at sea-level. When at length the glacial front had retreated beyond the St. Lawrence, sea-water entered Lake Ontario and passed up Ottawa River far above the city of Ottawa (Leverett, Monogr. U. S. Geol. Surv., LIII, plate XXI). South of the St. Lawrence, marine waters occupied what is now Lake Champlain and as much of the surrounding land as was then at or below sea-level. In his account Fairchild makes use of the plate which is here reproduced (map 31) from his article of 1917 (Bull. Geol. Soc. Amer., vol. XXVIII, p. 279, plate XI). This geologist believes that the Hudson formed for a while a connection with Lake Champlain, although the Hudson waters may not have been actually saline. But in Lake Champlain the presence of fossil marine mollusks and at least one whale skeleton shows that its waters were salt. The lines crossing the plate obliquely are the isobases which show the amount of elevation which has taken place along those lines since the end of the Pleistocene. South of New York City this is zero. At the northern end of Lake Champlain the elevation is 800 feet. This means that the north end of the lake for a while stood 800 feet lower than now. Marine fossils have, however, been found at an elevation of only about 300 feet. The waters which first occupied the lake and stood at the highest level were of glacial origin and fresh. When the ice-front had receded so as to open the St. Lawrence and admit sea-water, the northern end of the lake had been uplifted about 500 feet. It was then that the marine animals entered.
Other important papers to be consulted in this connection are as follows: One by J. B. Woodworth (Bull. 84 New York State Mus.); one by Charles E. Peet (Jour. Geol., vol. XII, 1904, pp. 415–469; 617–660), and two by Professor Fairchild (Bulls. 105, 127, New York State Mus.).
It is proper to say that certain glacial geologists maintain that the depression in the New England States has been less than supposed by Fairchild, and that the isobases curved around toward the north as the New England coast was approached, somewhat as represented by Taylor (Monogr. LIII, U. S. Geol. Surv., p. 503). Fairchild, in a later paper (Bull. Geol. Soc. Amer., vol. XXIX, 1918, pp. 187–244), has reached the same conclusion and presented a map on which are drawn the isobases, or lines passing through points affected by the same amount of post-glacial uplift; from this map 32 has been prepared. On his map the location of the heavy or solid lines is regarded by Fairchild as being based on clear evidence. Where the lines become thin the evidence is less trustworthy; where the lines are broken their positions are hypothetical. The numerals on the lines show the amount of uplift along those lines. Two points of importance are brought out on the map. The first is that Newfoundland formed an independent center of glaciation and of subsequent uplift, a conclusion based on good geological evidence. The second point is that the center of the Wisconsin glaciation was located southeast of James Bay, considerably farther south and west than is usually supposed. The confirmation of this is left to the future.
It does not seem to have been demonstrated that there are in Connecticut any Pleistocene deposits older than those laid down by the Wisconsin ice-sheet. In case Fuller (U. S. Geol. Surv. Prof. Paper 82) is correct in his determination of beds of the early, middle, and late Pleistocene on Long Island, it is to be expected that beds of corresponding ages will yet be recognized in Connecticut. Woodworth (17th Ann. Rep. U. S. Geol. Surv., pt. 1, p. 978) mentions deposits of clay at Berlin and at New Haven that may be older than the Wisconsin.
While the correlations recorded above of the Pleistocene of the New England States with the glacial and interglacial stages of the Mississippi Valley may be subject to modifications, it is interesting to learn that the presence of Middle and Early Pleistocene deposits in the Eastern States has received the recognition of so many students of glacial geology. The hope is awakened that in New England there may yet be found interglacial deposits which will furnish remains of Pleistocene vertebrates, as these have come to light from Throg’s Neck, New York, to southern Florida. It is possible that the astragalus of an equine animal (p. 183), found at Gay Head, Martha’s Vineyard, belongs to a species of Equus of early Pleistocene age.
In order to illustrate still further the events connected with the history of the Pleistocene in the region of the Great Lakes, three additional figures are introduced. One of these (map 33) shows J. W. Spencer’s conception of the drainage of the region in preglacial times. The areas now occupied by the lakes were then traversed by rivers. It will be observed that the rivers above Pittsburgh now discharging into the Ohio then emptied northward into the Erigan. This is shown also by a map (fig. 6) taken from Leverett (U. S. Geol. Surv. Monogr. XLI, p. 89). Figure 5, on page 287, shows the position of the shore of this Champlain Sea.
The number of Pleistocene vertebrates found in the New England States is limited, and most of them have been mentioned.
Somewhere on the coast of Maine have been found specimens of the fish Mallotus villosus (Gould, Proc. Bost. Soc. Nat. Hist., vol. III, 1848, p. 67). At Charlotte, Vermont, a white whale, Delphinapterus vermontanus, was found many years ago (p. 19). Some bovid teeth were found many years ago at Gardiner, Maine, and referred to Bison bison, but it is now believed that they are teeth of the domestic ox. However, Dr. G. M. Allen has reported from Cape Cod, Massachusetts, teeth of a young bison (p. 266). At Woodbury, Washington County, Vermont, at a depth of 7 feet, an antler and a piece of the upper jaw with five molars of Rangifer caribou (p. 244) have been discovered (Rep. Geol. Surv. Vermont, vol VI, p. 7). Mastodons have been discovered in Massachusetts at Coleraine and Shrewsbury (p. 47). Many years ago a tooth and a tusk and some bones of an elephant were found at Mount Holly, Vermont (p. 148); the writer refers the animal to Elephas columbi. An undetermined elephant has been found in Vermont at Richmond (p. 167). Walrus remains have been recovered at Addison Point (p. 23), Andrews Island (p. 23), Gardiner (p. 23), and Portland (p. 24), all in Maine; off Portsmouth, New Hampshire (p. 25); and on Martha’s Vineyard, Massachusetts (p. 25). At the latter place a tooth supposed to belong to the hooded seal (p. 26) was found long ago. With respect to the specimens found at this place there is some doubt as to their geological age. With the exception that the reindeer bones (p. 244) found near New Haven may be of pre-Wisconsin age, no Pleistocene vertebrate fossils older than Late Wisconsin appear to have been discovered anywhere in Connecticut. As shown elsewhere (p. 48), there were found long ago at Sharon, Litchfield County, remains which were identified as those of mammoth, but these have since been regarded as those of the common mastodon. Only a single vertebra was preserved.
Fig. 6.—Probable preglacial drainage of the Upper Ohio. From Leverett.
Mastodons have been found in four other places, Cheshire, New Britain, Bristol, and Farmington (pp. 47, 48). The animals which left their bones at those places certainly lived after the last glacial sheet had withdrawn from the State. As mentioned on page 291, Fairchild has found reasons for believing that, while the Wisconsin ice-sheet was withdrawing from the Hudson and Connecticut Valleys, the whole region was so depressed that these valleys became occupied by water at sea-level. In these waters there were laid down thick deposits which now stand at levels much above tide, varying, in Connecticut, from nearly 200 to about 300 feet. Map 31, reproduced from Professor Fairchild (Bull. Geol. Soc. Amer., vol XXVIII, 1917, plate XI) is intended to show how wide an extent of territory along the Connecticut Valley was then submerged. It is probable that the emergence of these deposits was not accomplished until after the glacier had retired beyond the State.
It will be observed (map 6) that the localities just mentioned, where the mastodons have been found, lie very close to or on the areas covered by the deposits mentioned. The pond in which the Farmington mastodon (fig. 6, No. 3) was buried is in a range of hills which must have stood as an island in the Connecticut inlet. While it is possible that mastodons lived on this island while the land was depressed, it is more likely that they lived there after it had been more or less elevated. Judging from the topographical maps, one may conclude that the mastodons that have been found at Cheshire (fig. 6, No. 1) and New Britain (fig. 6, No. 2) were buried in deposits that overlie those laid down at sea-level. Their time of existence must have been near the end of the Pleistocene. Too little is known about the mastodons reported from Bristol and Sharon to form any definite opinion about the stage of the Pleistocene when they lived; but it was probably after the withdrawal of the last ice-sheet.
From the geologist’s point of view there is hardly, if at all, another State which presents for solution more numerous or more interesting problems connected with the Pleistocene than does New York. Among these are the geography and topography of the State at the beginning of the Pleistocene; the number and identity of the glacial stages which affected its surface; the origin and development of the bordering Great Lakes, of the numerous interior lakes, and of the river courses, actual and abandoned. For a knowledge of these one must consult the various reports issued by the Geological Survey of the State; above all, the numerous and instructive papers that have been published by Professor H. L. Fairchild, of the University of Rochester.
For the student of Pleistocene vertebrate palæontology, the State of New York is not so attractive as some others; but it is far from being devoid of interest. Few species of vertebrates of Pleistocene age have been found in its deposits, and these, with one exception, belong to the latest episodes of the last glacial stage. So far as the writer is aware, the following list comprises all of the Pleistocene vertebrates known to have been found within the borders of the State; those marked with an asterisk (*) are now extinct:
Deposits of materials belonging to Pleistocene stages older than the Wisconsin are apparently of rare occurrence in the State. If existing they are usually concealed beneath the widely spread Wisconsin drift. On Long Island, Fuller (U. S. Geol. Surv. Prof. Paper 82) has described beds of gravels, sands, and clays, which he regards as belonging to the Nebraskan, Aftonian, Yarmouth, and Illinoian. None of these has furnished any vertebrate fossils. However, in 1866 (Smithson. Contrib. Knowl., vol. XV, art. 3, p. 16), Whittlesey reported that he had a tooth of a horse (p. 183) found at Fort Schuyler, Throg’s Neck, 18 feet below the surface. This must have been lying beneath the Wisconsin drift. Inasmuch as Fuller has found the Manhassett formation, regarded as equivalent to the Illinoian, around Manhassett Bay, within 4 or 5 miles of Throg’s Neck, it seems entirely reasonable to suppose that deposits of similar or earlier age exist at Throg’s Neck.
With the exception of small areas, the whole of the State was at one time covered by the ice-sheet of the Wisconsin stage. The glacial ice filled the basins of the Great Lakes, and overrode even the peaks of the Adirondack and Catskill Mountains. Only along the southern side of Long Island and in the loop formed in Cattaraugus County by Allegheny River does the ice-sheet appear to have been absent.
Nearly everywhere, even on the southern coast of Long Island as outwash, it left its burden of clay, sand, gravel and boulders, usually many feet in thickness; in the mountainous regions this drift material is present, at least in the valleys. At the extreme southern edge of the glacial sheet there was laid down the terminal moraine, which, more or less distinctly determinable, has been traced from the eastern end of Long Island to the southwestern corner of Cattaraugus County, and onward into Pennsylvania. This moraine is shown here on maps 3 and 6–A.
As the ice-sheet withdrew toward the north, the surface which it had occupied was, for many reasons, very uneven, and in the depressions there were formed numerous lakelets and lakes. Into the smaller lakes and ponds especially, were swept, by running water and blown by winds, coarse materials and dust, so that they began at once to fill. Water-loving plants in due time took possession of their borders, and in time marshes were formed. In some of these bodies of waters are now found deposits of shell marl, which show that for a long period the lakes and ponds were inhabited by fresh-water mollusks. Sometimes below this marl, but usually above it, is found a layer of peat, the product of the partial decay of the vegetation. It is in such peat-bogs, sometimes buried in the peat, sometimes in the marl, that have been found most of the bones and teeth of the fossil animals recovered. Inasmuch as such deposits lie upon the Wisconsin drift, it is certain that these animals lived, at the localities where found, after the retirement of the glacier from that locality; how long afterward one usually can not be certain.
It is in such Late Wisconsin deposits that have been found the numerous remains of mastodons on Long Island, on Staten Island, around New York City, and especially in Orange County (pp. 48–54). This county has furnished some of the most complete skeletons of mastodons ever discovered. Whether or not the conditions for their existence were more favorable in this region than in that between this county and the Finger Lake region may be regarded as doubtful; but it is certain that the conditions for the preservation of skeletons were extremely favorable.
A remarkable case is presented at Cohoes, where a part of a skeleton of a mastodon was found in one of the great pot-holes existing there, and another part of the same skeleton in a neighboring pot-hole. The case is discussed below.
In the western half of the State, after the foot of the glacier had retired beyond the divide between the present northward and southward flowing streams, bodies of water began to collect between the divide and the foot of the glacier. To these bodies, regarded as lakes, changing from time to time their dimensions and their outlets, have been given various names. At first, the waters that collected in the Finger Lake region found their outlet southward through the Susquehanna River; later through the Mohawk and Hudson; then westward into the Mississippi drainage; afterward through a channel leading around west and north of the Adirondacks and into Lake Champlain and down the Hudson; and finally, as now, into the St. Lawrence River (map 34).
The waters of the Erie basin, for most of the time, found their outlet toward the west into the Mississippi; but at a later time they escaped for a while eastward through central New York into the Mohawk. For information regarding these lakes one must consult Leverett and Taylor (Monogr. LIII, U. S. Geol. Surv.) and Fairchild (Bulls. 127, 160, N. Y. State Mus.).
From a study of the geological history we may arrive at some approximately correct ideas as to the time when the mastodons, elephants, horses, giant beavers, etc., lived within the limits of the State. Of these animals, apparently none of the specimens discovered up to this time belongs to any pre-Wisconsin stage, except the horse whose tooth was found at Throg’s Neck (p. 183). The history of our extinct horses and the depth at which the specimen was found indicate that the animal had lived either during the first or the second third of the Pleistocene.
We may be certain that none of the mastodons (p. 49) which have been reported from Long Island lived there while the northern border was occupied by the glacier, and the remainder by the ocean. Not until the land had risen to about its present level could mastodons have become buried in the muck-filled ponds where they have been met with. Where the glacier front was when mastodons got foothold on the island we can not tell certainly; but it required perhaps hundreds or probably thousands of years for the elevation of the island to the extent of about 100 feet. We can hardly doubt that the mastodon lived on up to near, possibly into, the Recent period (see map 34).
It is interesting to speculate on the time and manner of entombment of the skeleton, described on page 56, which was found at Cohoes, part in one pot-hole, part in another not far away. Hall adopted the theory that the carcass of the mastodon had been frozen in the glacial ice and, on the thawing of this ice, had been dropped into the pot-holes. In fact, he thus explained the frequent presence of mastodon skeletons in swamps. We have, however, no evidence that mastodons were ever thus frozen up in the ice of the glacier; but there is a possibility that this happened sometimes. If a skeleton should thus have been engaged in the moving stream of ice it is not probable that it would ever have emerged in a recognizable condition. In the production of cracks and crevices in the glacial ice, of which Hall spoke, the bones would have been broken up and scattered, if not ground to powder. If a cadaver had been frozen in the ice for any considerable time it would certainly have come out in such a waterlogged condition that it would hardly have floated. Weighted down by its heavy tusks, it would have drifted against rocks and at least the tusks would probably have been broken off. If we exclude the idea that the mastodon had first been frozen in the glacier, the writer sees no reason for denying that it might thus have been transported for some distance; but little is gained by granting it. The animal could as well have lived near Cohoes as farther up the Mohawk.
As stated on another page, James Hall concluded that the pot-holes belonged to some preglacial time. Professor H. L. Fairchild has expressed in a letter to the present writer the following opinion:
“When the ice-sheet melted from Cohoes the locality was 355 feet lower than it is to-day. Deep estuary deposits partially filled the Hudson Valley and buried the Cohoes district. The Mohawk channel at Cohoes is excavated through marine sediments. There is no suggestion of any river channel there previous to the present river work. The pot-holes are post-glacial, but they probably represent a more copious and vigorous flow than that of the present river. That was supplied by the diminishing Iromohawk, the latest outflow through the Mohawk Valley of the Iroquois water. In this view the pot-holes were drilled by the latest glacial waters.”
It appears that, when the mastodon skeleton fell into the pot-holes, these had been drilled long before; for the principal one had become filled with gravel to a depth of at least 10 feet. They were, therefore, probably well above the stream-level, except in times of high-water. However the carcass reached the locality, it must have arrived in a complete state. Had it already attained an advanced stage of decay, some limbs or the feet or the lower jaw, probably the whole head, weighted down as it was by the heavy tusks, would have dropped off. It may be assumed that the skeleton was lying on land or in some pond not far above the pot-holes. The flesh was not wholly decayed, and the bones were held together by the ligaments. While the skeleton was in this condition the river rose and swept it over the first pot-hole, where the right leg dropped off; and then onward over the second, where more of it was deposited. Some unimportant parts may have been carried farther, and some of the missing bones may have decayed in the pot-holes. After the bones were deposited there the pot-holes became slowly filled up, probably mostly during times of high-water, with muck and branches and trunks of trees of several species (Hay, Science, n. s., vol. XLIX, 1919, p. 378).
The retreat of the Wisconsin ice-sheet far beyond the St. Lawrence and the rise of the land to its present elevation, 350 feet above the sea at Cohoes, belong to the closing chapter of Pleistocene history. When the Cohoes mastodon was buried the ice-sheet was probably already north of the St. Lawrence and, as Professor Fairchild writes, 150 feet of the rise of the land had already occurred. The time could, therefore, not have been long before the beginning of the Recent epoch. If these animals lived at such a late time at Cohoes they doubtless existed at the same time in all parts of the eastern region where their remains have been discovered. They may have been able to occupy Long Island a little earlier than places further north, but the interval would be geologically inconsiderable.
The writer has learned of no discoveries of mastodon bones in materials laid down by the marine waters that occupied Lake Champlain, the St. Lawrence Valley, and that of Ottawa River, or in deposits overlying these marine beds.
On the basis of one of Professor H. L. Fairchild’s plates (Bull. 127, N. Y. State Mus., plate XXXV) the writer has prepared map 34, which is intended to show the position of the Wisconsin ice-sheet in New York after it had retired somewhat north of the divide. This divide is marked by a line of dots. The area then occupied by the ice is stippled. Lake Erie was already nearly free from ice and was discharging its water by way of the Mississippi. Impounded waters from the melting glacial ice were collecting in the region of the Finger Lakes, forming Newberry Lake, and escaping down the Susquehanna. The Mohawk afforded outlet for the water from the southeastern lobe of ice. Fairchild’s plates 36 to 42 show the successive positions occupied by the ice-front as it retired northward and the various lakes that were formed.
Although not many species of vertebrate animals have been found in the Pleistocene deposits of New York, a large number of localities have furnished remains of the mastodon, Mammut americanum. These localities are recorded and brief descriptions of the remains and their geological environment have been presented on pages 48–63. The localities are indicated on map 34. It will be seen that several specimens have been found on Long Island and many in Orange County, in the southeastern corner of the State. In the western half of the State most of the finds occur within the area once occupied by the successive lakes. The animals could have lived there only after the ice-sheet and the lake waters had disappeared. It will be seen that a few finds have been made close to the shores of the present lakes. The animals must have lived there at the very end of the Pleistocene, if not within the Recent epoch.
The finds of other vertebrates are recorded on the following pages: Equus sp. indet. on page 183; Platygonus compressus on page 212; Bison bison on page 266; Odocoileus virginianus on page 226; Cervus canadensis on page 235; Rangifer caribou on page 245; Elephas columbi on page 149; Elephas primigenius on page 131; Castor canadensis on page 272; Castoroides ohioensis on page 272.
In 1850 (Proc. Amer. Assoc. Adv. Sci., vol. II, pp. 255–256), W. C. Redfield reported that he had received remains of a fox of the genus Vulpes from Gulf Summit, Broome County. The lower jaw and other bones had been discovered in a cutting of the New York and Erie Railroad, 40 feet below the natural surface. The deposit above these bones was evidently the Wisconsin drift. The fine clay inclosing the bones may have belonged to the Sangamon, or even some older interglacial deposit. It is impossible to say whether this fox was Vulpes fulvus or Urocyon cinereoargenteus.