Cretaceous (ILK;0)

State	Illinois
Name	Cretaceous
Geologic age	Cretaceous
Original map label	1360
Comments	Includes the Owl Creek Fm., McNairy Sand, and Tuscaloosa Gravel in the southern part of the state and the Baylis Fm. in the northern part of the state. Based on the stratigraphic section on the 1967 paper map, as a group, the Cretaceous units are about 65% sandstone, 25% clay, 5% gravel, and 5% siltstone
Primary rock type	sandstone
Secondary rock type	clay or mud
Other rock types	gravel; siltstone
Lithologic constituents	Major Sedimentary > Clastic > SandstoneBased on the stratigraphic section on the 1967 paper map, as a group, the Cretaceous units are about 65% sandstone, 25% clay, 5% gravel, and 5% siltstone Minor Unconsolidated > Fine-detrital > ClayBased on the stratigraphic section on the 1967 paper map, as a group, the Cretaceous units are about 65% sandstone, 25% clay, 5% gravel, and 5% siltstone Incidental Unconsolidated > Coarse-detrital > GravelBased on the stratigraphic section on the 1967 paper map, as a group, the Cretaceous units are about 65% sandstone, 25% clay, 5% gravel, and 5% siltstone Sedimentary > Clastic > SiltstoneBased on the stratigraphic section on the 1967 paper map, as a group, the Cretaceous units are about 65% sandstone, 25% clay, 5% gravel, and 5% siltstone
Map references	Willman, H.B., and others, (compilers), 1967, Geologic Map of Illinois: Illinois State Geological Survey, scale= 1:500,000, paper.
Unit references	Willman, H.B., and others, (compilers), 1967, Geologic Map of Illinois: Illinois State Geological Survey, scale= 1:500,000, paper.
Geographic coverage	Adams - Alexander - Johnson - Massac - Pike - Pope - Pulaski - Union