Cretaceous undivided

Cretaceous undivided, includes Post Creek (Tuscaloosa), McNairy, and Owl Creek Formations (southern Illinois).
State Illinois
Name Cretaceous undivided
Geologic age Upper Cretaceous (Campanian to Maastrichtian)
Lithologic constituents
Sedimentary > Clastic > Sandstone (Bed)Sandstone of Post Creek (Tuscaloosa) Fm contains gravel.
Sedimentary > Clastic > Mudstone > Shale (Bed, Glauconitic, Carbonaceous)Owl Creek Fm contains glauconite. McNairy Fm is carbonaceous.
Sedimentary > Coal (Bed)
Comments Thickness from stratigraphic column for southern Illinois (south of 40 degrees north latitude), from oldest to youngest: Post Creek (Tuscaloosa) Fm (0-75’), McNairy Fm (0-450’) and Owl Creek Fm (0-10’). [The Baylis Fm (Kb) in western Illinois is laterally equivalent to the Post Creek Fm. Ku is mapped only in southern Illinois.]

Kolata, D.R., comp., 2005, Bedrock Geology of Illinois: Champaign, Ill., Illinois State Geological Survey, Illinois Map Series 14, scale 1:500,000.

NGMDB product
Counties Alexander - Massac - Pope - Pulaski - Union