The Glasford crater is a buried impact crater in southern Peoria County, Illinois, in the United States. It is in diameter and the age is estimated to be less than 430 million years (Silurian or younger). The Glasford crater was discovered by drilling wells for underground natural gas storage. References Impact craters of the United States Geology of Illinois Silurian impact craters Silurian Illinois .craters Landforms of Peoria County, Illinois Landforms of Illinois