A fragment of the hinder end of what appears to be the lower left second molar shows 7 ridge-plates remaining. These form two series, an inner and an outer, entirely separate from each other. This condition is sometimes seen in little-worn teeth.
The geology of this region may be studied on the Tallula-Springfield Folio, No. 188 of the U. S. Geological Survey. The Tallula Quadrangle includes a narrow strip of the eastern border of Cass County. Here the surface forms a nearly level prairie. According to the geologists Shaw and Savage, the surface in the region next to Cass County and much of the rest of the quadrangle is covered by a blanket of loess. Its thickness varies from 4 to 20 feet; under this, sometimes, in wells, is to be found a dark-colored ill-smelling deposit, of no great thickness, which is believed to represent the Sangamon stage. Underlying the loess everywhere is the Illinoian drift.
As regards the geological age of the elephant described above, it is quite certain that it lived after the Illinoian stage. It is quite probable, too, that its teeth and bones were found in the loess which overlies the Sangamon soil in some places in the quadrangle. This loess may have accumulated during the Iowan glacial stage or during the succeeding Peorian interglacial. Considering what we know about the habits of Elephas primigenius, it appears most probable that the animal in question passed its life during some part of the Iowan.
3. Kewanee, Henry County.—In the collection of the University of Illinois, at Champaign, is a fragment of an upper molar of Elephas primigenius, found at Kewanee. It was discovered in 1910, in making an excavation for the National Tube Company, and was presented to the university by Mr. J. E. Kemp, at that time engineer in charge of the work of excavation. This gentleman has furnished very exact information regarding the discovery of the tooth and the nature of the deposits passed through.
Mr. Kemp himself saw the tooth taken out and states that it was found at a depth of about 12 feet. As to the materials passed through, Mr. Kemp writes:
“After the first 2 feet of soil carrying organic matter we have 5 feet of yellow clay above the ground-water level, and below this approximately 3 feet of yellow clay which becomes very soft unless carefully drained before working. This yellow clay then merges into bluish clay, hard and better packed, going to a depth of approximately 20 to 21 feet. At this level we meet with that black soil which is known locally as ‘the chip yard’ and which contains vegetation and pieces of wood, as you describe. This ‘chip yard’ is a softer stratum than the overlying blue clay and caused difficulty in the excavation of a hole approximately 20 feet by 30 feet and 20 feet deep, as the vibration of the reciprocating engines in the building caused the bottom to rise in little hillocks over night, and the last 2 feet of excavation had to be dug out and 24 inches of concrete placed in the bottom, in order to preserve the excavation.”
At Galva, 10 miles southwest of Kewanee, in cuttings along the railroad, is found a section which illustrates the geological situation at Kewanee (Monogr. XXXVIII, U. S. Geol. Surv., p. 126, plate X). There is at the top 4 feet of loess, 1 foot of Sangamon soil, 4 feet of Illinoian drift; in another section nearby there are 12 feet of loess, 2 feet of Sangamon soil, and 40 feet of Illinoian drift.
Another section at Galva is described by Leverett (op. cit., p. 130). The loess is 15 feet thick, beneath which is a mucky soil about 1 foot in depth, which caps the Illinoian till sheet. In this soil a log about a foot in diameter and several feet long was found embedded. Alden and Leighton (Iowa Geol. Surv., vol. XXVI, p. 170) mention this occurrence.
From these examples it becomes evident that the “chip bed” at Kewanee is a Sangamon soil overlain by loess. The elephant tooth at a depth of 12 feet must have been buried in the blue clay. This, however, is probably the unweathered part of the loess. If so, the mammoth tooth found at Kewanee is to be referred to the early Peorian stage.
4. Penny’s Slough, Henry County.—In the collection of the Davenport Academy of Science is a large upper left hindermost molar tooth, labeled as having been found in Penny’s Slough. It is very large, the length along the base being 357 mm. (about 14 inches), and the height of the eighteenth plate is 175 mm. There is an unusual number of the plates, apparently 27. There are 7 plates in a line 100 mm. long. The tooth is moderately worn. There are 2 large roots in front and 2 rows of smaller ones behind these. The base is straight and the plates little warped.