Deposits of sand and gravel, found in many parts of Illinois, provide
large quantities of material for concrete, railroad ballast, road
gravel, building sand, molding sand, and other uses. Glacial deposits
are the principal sources of sand and gravel, but in extreme southern
Illinois where there is no glacial drift the main source of supply is
Tertiary gravel and Devonian chert gravel.
[Illustration: Figure 11—The clay industry is scattered widely in
Illinois. Many manufacturing plants are located at the clay pits.]
KEY
Pit or Plant
Almost every county has some sand and gravel, but the major areas of
production are northeastern Illinois and some of the major rivers.
Considerable tonnages of sand and gravel are dredged from bars in the
channels of the Mississippi, Ohio, and Wabash Rivers.