1890. J 
457 
[Leverett. 
hard till below the newer drift is frequently exposed in ravines in the 
moraines toward the south, and can be traced continuously back 
from the district south of the outermost moraine until the fresher 
drift becomes too thick for ravines to reach it. Along these ra- 
vines the following section is frequently exposed : 
1. Surface soil and leached subsoil, 2-6 feet. 
2. Yellowish-gray till, 6-10 “ 
3. Blue till, soft and fresh in appearance, 0-50 “ 
4. Soil and leached sub-soil, 3 “ i 
5. Brown till, hard, dry, and partially cemented, 5-10 “ 
6. Blue till, hard, dry and partially cemented, trav- 
ersed by brown streaks, 5-50“ 
Where ravines fail to reach the lower drift sheet it has fre- 
quently been struck in wells, so that its occurrence is known as far 
north as Mendota, Illinois, the vicinity of the Kankakee river and 
in central Indiana, a distance of not less than two hundred and 
fifty miles from the southern margin of the drift in Illinois, and 
nearly one hundred and fifty miles from the southern moraine of 
the newer drift in that state. 1 
It is not the great extent of retreat and subsequent advance of 
the ice nor the mere presence of a buried soil that I wish to em- 
phasize, but the amount of oxidation and leaching which took place 
in and below the buried soil during this retreat. Near Mendota, 
Illinois, I examined specimens of the buried soil, subsoil and un- 
derlying till from several borings, the.depth to the buried soil rang- 
ing from ninety-four to one hundred and twenty-eight feet. The 
soil and subsoil resemble the underlying till in containing com- 
mingled sand, clay and pebbles, but they lack the limestone frag- 
ments and calcareous rock-flour which characterize the till. The 
leaching is so perfect that no response with acid was obtained with- 
in three feet of the surface of the buried soil, but below this depth 
the till became within a foot or two very calcareous. Similar re- 
sults followed the test applied along the ravines in southern Indi- 
ana and southwestern Ohio, both in exposures beneath the newer 
drift, and in the district south of its margin, the depth of leaching 
being little, if any, greater than at Mendota. 
The surface of the newer drift of this region is leached to various 
Juried soils are reported from various places in northeastern Illinois and southern 
Wisconsin, hut I have had no opportunity to examine them, and have been unable to 
ascertain whether or not the leached subsoil is found in connection with them. 
