WHERE DO SAND AND GRAVEL COME FROM?
Glacial deposits of sand and gravel are the chief source of these materials in Illinois, but chert or flint gravels that are older than the glacial deposits are known and utilized locally in western and extreme southern Illinois. Sands of recent origin are dredged from deposits in the larger rivers and streams ([fig. 17]), and commercial silica sand is produced from sandstone bedrock.
Figure 17—Dredge equipment used in producing sand and gravel.