STRATIGRAPHY AND STRUCTURE OF THE FINLAY MOUNTAINS, TEXAS
BY CLAUDE C. ALBRITTON, JR., AND WILLIAM O. HAM*
The Finlay Mountains of southern Hudspeth County, Texas, lie approximately on the boundary between the Sierra Madre and the Basin-and-Range structural provinces. The mountains are of Permian and Lower Cretaceous sedimentary rocks cut by dikes and parted by sills and laccoliths of late Cretaceous or Tertiary age. Valleys and small intramontane basins contain Cenozoic alluvial deposits similar to those in the Hueco Basin to the south.
Permian rocks aggregating approximately 1700 feet in thickness consist of flaggy siltstone, shale, cherty limestone, and conglomerate. Marine fossils, including some typical Leonard species, are found at many horizons from the bottom to the top of the section.
Resting with angular unconformity on the Permian is the oldest Cretaceous formation, the Campagrande, 630 feet thick at the type locality, and consisting mostly of siltstone and impure limestone. . . .