Thornton Quarry - Wikipedia
The quarry contains Silurian reefs which formed when the Michigan Basin was covered in sea water more than 400 million years ago. History. The first settlers came to Thornton, Illinois, in 1834. Gurdon Saltonstall Hubbard received 160 acres of land from Shabonna, his Indian wife. In 1836 Hubbard opened the first quarry on Kinzie Street.