Hooper Formation of Wilcox Group. Mostly mudstone with various amounts of sandstone, minor lignite, ironstone concretions, and locally glauconite in lowermost part. Mudstone, medium- to dark-gray, weathers yellowish brown. Sandstone, in upper part --fine- to medium-grained, moderately well-sorted, cross-bedded, units 5 to 30 feet thick, light-gray to pale yellowish brown; in lower part --very fine-grained, well-sorted and in part argillaceous, cross-bedded, locally burrowed, units a few inches to 10 feet thick, yellowish brown to moderate brown. Average thickness 500 feet. Lies above Wills Point Formation of Midway Group and below Simsboro Formation of Wilcox. Age is Eocene.
Mapped in Robertson, Falls, Limestone, Freestone, and Navarro Cos., eastern TX.

Source: Publication.