| State | Texas |
|---|---|
| Name | Hannold Hill Member of Tornillo Formation |
| Geologic age | Eocene |
| Lithologic constituents |
Major
Sedimentary > Clastic > Conglomerate (Bed)
Minor
Sedimentary > Clastic > Sandstone (Bed)
Sedimentary > Clastic > Mudstone > Claystone (Bed)
Incidental
Sedimentary > Coal > Lignite (Bed)
|
| Comments | Mostly clay, some sandstone and channel conglomerate; clay contains thin sandstone beds and lignite, some beds contain calcareous concretations, gray and maroon; sandstone, coarse grained, conglomeratic, crossbedded, pebbles of black chert and Comanchean limestone, gray, brownish gray and grayish white; Exhibit Sandstone, 320 ft. above base, 12 to 15 ft. thick, contains vertebrate fossils; thickness up to 850 ft. crops out in northern part of Big Bend NP |
| References | Bureau of Economic Geology, 1979, Emory Peak--Presidio Sheet, Geologic Atlas of Texas, University of Texas at Austin.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. |
| NGMDB product | |
| Counties | Brewster |