Maquoketa Formation
# Maquoketa Formation

The Maquoketa Formation is a geologic formation in Illinois, Indiana. Iowa, Kansas, Minnesota, Missouri, and Wisconsin. It preserves mollusk, coral, brachiopod and graptolite fossils dating back to the Darriwilian to Hirnantian stages (Edenian to Richmondian in the regional stratigraphy) of the Ordovician period.

