The Eastern Shelf was a constructional platform developed on the margin of the sediment-starved Midland Basin during Late Pennsylvanian and Early Permian time. A mixed terrigenous-carbonate sedimentary province characterized the shelf during most of its history.

Geologic map that depicts surface geology of Crosby, Dickens, and King Counties and parts of Hale, Floyd, Motley, Cottle, King, Lubbock, Lynn, Garza, Kent, and Stonewall Counties. The Lubbock Sheet honors the late Dr.

At the northern end of the Coahuila platform, the thinned Comanchean sequence consists of the newly named Sixshooter group of carbonate formations underlain by the newly named Yearwood formation.