In Hyde Park, as detailed on page [71], considerable parts of a mastodon and some remains of a horse (p. [185]), probably Equus complicatus, have been discovered. The age of these remains certainly antedates that of the Wisconsin; and it is not improbable that the excavation was carried through the Illinoian drift into an older and probably interglacial deposit. Professor Fenneman writes that this area is only thinly covered by Illinoian drift and is also far beyond the limits of the Wisconsin outwash.
The occurrence of Bison latifrons near Fincastle, in Brown County (p. 257), must be noted. The fine pair of horn-cores now in the Cincinnati Society of Natural History may have been buried in deposits of Sangamon age. It is not, however, impossible that they were in an interglacial bed below the Illinoian drift.
On page [135] there has been given an account of the finding of a skull of Elephas primigenius, somewhat more than a mile east of New Burlington. The locality is treated in proper detail in N. M. Fenneman’s paper entitled “Geology of Cincinnati and Vicinity” (Bull. 19, Geol. Surv. Ohio, p. 158). According to this account the skull was buried in a lacustrine silt laid down probably when the Wisconsin glacier was not far away from that region. The surrounding country is covered with Illinoian drift. This skull is now the property of the U. S. National Museum.
In the collection of the Ohio State Archæological and Historical Society at Columbus there are remains of Platygonus compressus, jaws and good teeth, which were found about a mile north of Chalfants, in Perry County, and along Jonathan Creek. This place is within the area covered by Illinoian drift. It is possible that the remains are as old as the Sangamon, but it is also possible that they belong to the close of the Wisconsin stage (p. [215]).
The writer knows of no other fossil vertebrates that have certainly been found within the area occupied by the Illinoian till as a surface deposit.
As shown by map [36], by far the larger number of Pleistocene vertebrates which have been discovered in Ohio have been met with within the region occupied by the Wisconsin drift-sheet. One reason for this preponderance is the greater area included. Another reason may be found in the fact that the conditions were more favorable for the preservation of teeth and bones. Much of the country was flat and swampy and the bones buried in clay and muck have always been soaked with water. Also there has been less erosion going on. Erosion leads to exposure and therefore to destruction of skeletons.
On the map referred to are shown the various moraines that were left by the Wisconsin ice-sheet in its retreat toward the north. Inasmuch as most of the burials were in swamps resting on the drift, the animals must have lived and died there after the ice had left that vicinity; how long after one may not be able to determine. The mastodons and elephants which have been found close to the shore of Lake Erie, especially if buried near the surface, must have lived there at or after the time when the waters had shrunken into Lake Warren. Such cases are furnished by the mastodons and elephants found at Amboy (east of Ashtabula) (pp. 137, 150), at Cleveland (p. [79]), and in Brownhelm Township, in Lorain County (p. [79]). The town of Amboy is about 130 feet above lake level and the gravel-pit which there furnished Elephas primigenius and E. columbi was probably at about the same level. The writer has not been able to confirm any case in which remains of proboscideans have been met with on the south shore of the lake at a level lower than the Warren beach. Mastodons may be traced to a lower level at the western end of the lake. The one found in Springfield Township, Lucas County (p. [77]), was buried in deposits only about 45 feet above Lake Erie. As shown by the topographical maps, the descent from this place and from Bowling Green, Wood County, to the lake is a gradual one. It may become possible to follow the presence of the mastodons, the elephants, and the giant beaver in Ohio up to the time when the lake assumed its present level.
For information regarding the several interesting discoveries of the giant beaver (Castoroides ohioensis) pages 273 to 275 may be consulted.
It is hardly necessary to take up one by one all the cases of vertebrates that have been met with within the area covered by Wisconsin drift. With the few exceptions noted below, their geological age is usually to be regarded as Late Wisconsin. Along the southern border of this drift, where the remains are deeply buried, it is not unlikely that they lie in a pre-Wisconsin interglacial deposit. Along Great Miami and Muskingum Rivers there is always a possibility that the fossils may occur in a terrace or in a deep valley deposit of Illinoian age.
About a mile east of Overpeck, Butler County, there has been found the skull of an extinct bear, Ursus procerus Miller (Hay, Geol. Surv. Indiana, vol. XXXVI, 1912, pp. 772–776, figs. 71–73). It was found at a depth of 28 feet and about 3 or 4 feet above the limestone rock of that region. To the writer it seems quite certain that the Wisconsin drift had been penetrated and that the skull was in either a Sangamon interglacial deposit or something still older.