110 
The American Geologist. 
February, 1864 
diverse rock formations whose decay has supplied the soils of 
the driftless portions of the state. Accompanying this ex- 
hibit, a colored map showed the areas of the several varieties 
of soil and the courses of the marginal moraines, principal 
eskers, and other drift ridges. A tabular statement of the 
origin and distribution of these soils, prepared by Air. Lever- 
et t, is as follows : 
Soils of Illinois. 
Variety. 
Origin or 
Mode of 
Deposition. 
Residuary. 
Decay of the 
underlying 
rocks. 
Stony or boul- 
der-clay, till. 
Glacial. 
Gravelly. 
Sandy. 
Glacial over- 
wash, fluvial 
and lacus- 
trine. 
Glacial drain- 
age. 
Fluvial. 
Lacustrine. 
Eoliarj. 
Silts pervious 
to water — 
(chiefly the 
typical loess). 
Silts slowly 
pervious to 
water. 
Slowly flow- 
ing waterp, 
and perhaps 
wind (in 
part). 
Slowly flow- 
ing waters, 
and perhaps 
wind (in 
part). 
Areal, Distribution. 
Driftless portion of the state, where- 
ever the loess, as well as the glacial 
drift, is absent. 
Mainly in the northeastern quarter of 
the state, where loess and silts are 
absent. The Shelbyville moraine 
forms the southern boundary and 
chiefly the western boundary. In 
northern Illinois boulder-clays form 
the soil on the older drift area be- 
tween the Shelbyville moraine and 
the loess of the Mississippi valley. 
With the boulder-clay, in the north- 
eastern part of the state, and along 
streams leading away from the Shel- 
byville and later moraines. This 
variety of soil includes gravel knolls 
and ridges, overwash gravel plains, 
terraces, and raised beaches. 
Mainly in basins along the Kankakee, 
Green and lower Illinois rivers; old 
lake bottom and raised beaches near 
Chicago; also on bottomlands and 
fringing in many places the low bluffs 
of streams; and locally developed on 
areas of glacial formations. 
Along the Mississippi, lower Illinois, 
lower Wabash, and lower Ohio rivers; 
also between the Illinois and the Mis- 
sissippi from the Green river basin 
south to the latitude of Peoria; and 
in the basin of the Big Bureau creek 
in Bureau county. 
Mainly in west central Illinois, west of 
a line connecting Alton, Litchfield, 
Pana, Decatur, and Peoria; also on 
the eastern border of the Mississippi 
valley loeBS belt in the northern part 
of the state. 
