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Delaho Formation and unit 9 of Rawls Formation

Delaho Formation and unit 9 of Rawls Formation NOTE: This unit is represented within the map unit explanation of (Geol. Map of Texas, 1992, Bur. Econ. Geol.) but does not occur on the map and is NOT included in the spatial data.
NameDelaho Formation and unit 9 of Rawls Formation
Geologic agePhanerozoic | Cenozoic | Tertiary | Miocene
Original map labelMd
Commentssandstone and conglomerate, pebbles dominantly Tule Mountain Trachyandesite, basalt pebbles dominant in upper part to the south (in Emory Peak-Prisidio Slheet (1979); sandst. composed mostly of volcanic rock fragments; festoon crossbedding will developed; Smoky Creek Mbr. thickness as much as 1,100 ft. Lower unnamed member thickness about 1,100 ft, total about 2,200 ft thick. Unit 9 of Rawls Fm is redefined as Closed Canyon Formation, mostly sedimentary rock (fan alluvium and basin-fill), alkali basalt lavas, dikes, and small plugs, and rare, 5-m thick, rhyolitic or quartz trachytic ash-flow tuff that accumulated with early basin-and-range faulting between 25 and 18 Ma ago.
Primary rock typesandstone
Secondary rock typebasalt
Other rock typesconglomerate
Lithologic constituents
Sedimentary > Clastic > Sandstone (Flow)
Sedimentary > Clastic > Conglomerate (Flow)
Igneous > Volcanic
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.
Henry, C.D., McDowell, F.W., Price, J.G., and Smyth, R.E., 1986, Geochronology of Tertiary igneous rocks, Trans-Pecos, Texas, in Price, J.G. and others, eds., Igneous geology of Trans-Pecos, Texas: The University of Texas at Austin, Bureau of Economic Ge

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