|Geologic age||Early Cretaceous|
Sedimentary > Clastic > Conglomerate (Bed)
Sedimentary > Carbonate > Limestone (Bed)
Sedimentary > Clastic > Mudstone > Shale > Black-shale (Bed)
Sedimentary > Clastic > Sandstone (Bed)
|Comments||On Marfa Sheet (1979) in mountains west of I-90 and east of Rio Grande, is basal Cretaceous unit exposed north of Chinati Mtns, Presidio Co. Overlain by Cretaceous Bluff Mesa Fm. and disconformably overlies Permian Pinto Canyon Fm. Limest.-pebble conglomerate, limestone, shale, marl, and sandstone. Upper part 500-550 ft of cliff-forming units of red ls, red and purple shale, brown sandstone. Lower part is about 100 ft of cliff-forming conglomerate of well-rounded pebbles and cobbles of limestone, some chert, boulders of Pinto Canyon Fm, grades up to nodular, fine-grained limestone.|
Plummer, F.B., and Moore, R.C., 1921, Stratigraphy of the Pennsylvanian formations of north-central Texas: University of Texas Bulletin 2132.
Bureau of Economic Geology, 1992, Geologic Map of Texas: University of Texas at Austin, Virgil E. Barnes, project supervisor, Hartmann, B.M. and Scranton, D.F., cartography, scale 1:500,000.
|Counties||Culberson - Hudspeth - Presidio|