Type Formation Thickness 10 to 100 ft. | Underlies Thebes Formation Primary Slate | |
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 Ordovician period.
References
Maquoketa Formation Wikipedia(Text) CC BY-SA