Study of Permian, Cretaceous, and Cenozoic rocks in the 30 Kent quad- rangle is important to an understanding of the geology of Trans-Pecos Texas. Most of the Cretaceoua rock units of central Texas lose their lithostratigraphic identity when traced into west Texas. The Kent quadrangle, astride the Diablo Platform, is one of the critical areas of intervening stratigraphy between central Texas to the east and the geosyncline in Mexico to the west and southwest.