THE AGE OF THE MAMMALIAN FOSSIL FAUNA 5°07 
rounded. The till is much more oxidized than the over- 
lying loess. In the contact zone between the till and 
the loess are the lime concretions from which the mam- 
malian remains were obtained. Thickness . . . 1-3 
Limestone, Mississippian age, about . . oe LOO 
Salient points regarding the drift.—As noted above, the glacial 
till exposed at this quarry is very thin and much more oxidized 
than the overlying loess. At the next quarry to the northwest, 
a patch of glacial till about 12 feet thick lies beneath the loess, 
strikingly set off from the loess above by a chocolate brown, 
weathered zone. The face of the exposure above the limestone 
cliff was too precipitous to admit of detailed study, but in the 
succeeding quarry to the northwest, at Plant No. 3 of the Mississippi 
Lime and Material Company, near the northeast end of the quarry, 
18 feet of till above the limestone and below fossiliferous loess was 
accessible for study. 
The till is a typical pebbly clay till. Its top is rounded and 
marked by a pebble band. The till is also oxidized to dark brown, 
changing below within a few feet to a yellowish brown to yellow 
color. The matrix of the till and the limestone pebbles are leached 
for about 8 feet down from the summit of the till, but where the 
slope of the till cuts down to a lower level this leached zone is 
diminished to about 3 feet. Beneath, the till is highly calcareous, 
and contains lime concretions up to about 8 inches in diameter. 
No such concretions occur in the overlying loess. The drift breaks 
into small polyhedral forms, due to the numerous intersecting 
joints. The surfaces of these joints are coated with oxide of 
manganese. 
Age of the drift—That the drift is much older than the loess is 
clearly shown by the weathered zone at its top. Its geographic 
location brings it within the possibility of being Illinoian in age; 
but there are strong suggestions that it may be as old as the Kansan. 
The 8-foot depth of the leached zone beneath fossiliferous and cal- 
careous loess, the chocolate brown color of the upper part of the 
oxidized zone, the coating of manganese dioxide along the numer- 
ous joints which transect the till body, and the large concretions 
t Fortunately the writer was able to have Mr. John D. McAdams, son of the 
collector, verify the horizon and the concretions as the source of the fossils. 
