| State | Illinois |
|---|---|
| Name | Tertiary and Cretaceous undivided |
| Geologic age | Upper Cretaceous (Campanian) to Tertiary (Pliocene) |
| Lithologic constituents |
Major
Sedimentary > Clastic > Mixed-clastic > Siltstone-mudstone (Bed, Glauconitic, Carbonaceous)Silty shale is portrayed on stratigraphic column. Owl Creek and Clayton Fms contain glauconite. McNairy Fm is carbonaceous.
Sedimentary > Clastic > Sandstone (Bed)
Minor
Sedimentary > Coal (Bed)
|
| Comments | Thickness from stratigraphic column for southern Illinois (south of 40 degrees north latitude), from oldest to youngest: Post Creek Fm (0-75'), Baylis Fm (0-100'), McNairy Fm (0-450'), Owl Creek Fm (0-10'), Clayton Fm (0-20'), Porters Creek Fm (0-150'), Claiborne and Wilcox Formations (0-300'), Mounds Gravel (0-70'), Grover Gravel (0-50'). The Baylis Fm (western Illinois) is laterally equivalent to the Post Creek Fm (southern Illinois); the Mounds Gravel is laterally equivalent to the Grover Gravel. [TKu is mapped only in southern Illinois.] |
| Stratigraphic units | Baylis Formation, Post Creek (Tuscaloosa) Formation, McNairy Formation, Owl Creek Formation, Clayton Formation, Porters Creek Formation, Claiborne Formation, Wilcox Formation, Mounds Gravel, Grover Gravel |
| References | 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 - Union |