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Hannold Hill Member of Tornillo Formation

Hannold Hill Member of Tornillo Formation
State Texas
Name Hannold Hill Member of Tornillo Formation
Geologic age Phanerozoic | Cenozoic | Tertiary | Eocene
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
Primary rock type clay or mud
Secondary rock type sandstone
Other rock types conglomerate; coal
Lithologic constituents
Major
Sedimentary > Clastic > Conglomerate (Bed)
Minor
Sedimentary > Clastic > Mudstone > Claystone (Bed)
Sedimentary > Clastic > Sandstone (Bed)
Incidental
Sedimentary > Coal > Lignite (Bed)
Map references
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
Unit references
Bureau of Economic Geology, 1979, Emory Peak--Presidio Sheet, Geologic Atlas of Texas, University of Texas at Austin.
Counties Brewster