Simsboro Formation of Wilcox Group. Mostly sand, some mudstone, clay, and mudstone conglomerate. Sand, locally indurated, ranges from moderately well-sorted fine sand to sandy mudstone-boulder conglomerate, typically medium to coarse grained, cross-bedded, light gray, commonly weathers reddish brown. In uppermost part thin lenses of clay and mudstone, medium to dark gray. Forms gently rolling hills covered by dense growth of oak. Thickness up to 300 feet, pinches out in northern Freestone County, eastern Texas. Lies above Hooper Formation and below Calvert Bluff Formation, both of Wilcox Group. Age is Eocene.
Mapped in Robertson, Falls, Limestone, and Freestone Cos., eastern TX.

Source: Publication.