The Thornton Quarry located near Chicago, Illinois is the site of a 420 million year old Silurian reef. The reef was formed in a shallow shelf, epicontinental sea environment, so the rocks of the quarry are filled with fossils! Many of the beds in the quarry are naturally gently tilted, and the structure has an… Continue reading Thornton Quarry, Illinois
Emily Zawacki, Ph.D. 