Pleistocene Deposits of Illinois. — Hershey. 
287 
5. Scott, W. B. Notes on the Osteology and Systematic Position of 
Dinictis felinci Leidy, (foot note 2), Proe. Acad. Natl. Sci., 1889. 
6 Scott, W. B. The Mammalia of the Deep River Beds, Trans: Am. 
Phil. Soc., vol. xvii, pp. 55-185. 
EARLY PLEISTOCENE DEPOSITS OF NORTHERN 
ILLINOIS. 
By Oscar H. Hershey, Freeport, Ills. 
Introduction. 
In the spring of 1892, excessive rainfall, with consequent 
prolonged flooding of the streams of northern Illinois, exca¬ 
vated or re-opened an old ravine on the south bank of Yellow 
creek, one and a half miles south of the city of Freeport, 
thereby exposing a very interesting section through clays 
and silts, underlying and consequently older than the Kansan 
drift sheet of the region. Since then, the formation of an 
extensive talus has greatly obscured the section, and. as many 
years may elapse before it can be again studied, it will be 
well to place it on record, and the present paper is an attempt 
to discuss the significance of its phenomena. 
The following is the section as exposed several years ago: 
Section on Yellow creek near Freeport. 
Thickness. 
1. Black surface soil. 1 foot. 
2. Sandy brown clay, chert, and boulders. 1 “ 
3. Gray “hard pan,” with some glacial pebbles. 6 feet. 
4. Red clay and chert. 8 inches. 
5. Laminated, variegated clays. 1 foot. 
6. Carbonaceous, laminated clay. 4 inches. 
7. Light brown, laminated silts. 4 feet. 
8. Transition to next. 1 foot. 
9. Blue, laminated silts, exposed. 5 feet. 
Total.20 feet. 
Loess, Aftonian, and Kansan Deposits. 
The black soil at the surface of this section has been formed 
from the remnant of the loess mantle which overspreads the 
region, but its unusual thinness is due to its situation on the 
edge of a bluff, favoring its rapid erosion. Intervening be¬ 
tween it and No. 2, there are usually from 5 to 40 feet of clays 
and silts belonging to the several members of the loess of the 
Pecatonica basin; but, as above indicated, the loess has been 
reduced here to a soil layer of one foot, resting directly on the 
reddish brown clay of No. 2. 
