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Eocene volcanic rocks

Eocene volcanic rocks
State Texas
Name Eocene volcanic rocks
Geologic age Phanerozoic | Cenozoic | Tertiary | Eocene
Comments igneous rocks mapped on Christmas Mt. on Emory Peak-Presidio Sheet (1979) Brewster Co., Big Bend Natl Park. Map description is given only as extrusive or intrusive igneous rocks of Tertiary age on that map. Petrography of sample coll. at locality no. 195 on Little Christmas Mt. (Maxwell and others, 1967, p. 218, Table 13)--Prophyritic quartz aegirine-augite trachyte. varies in composition approaches rhyolite.
Primary rock type rhyolite
Secondary rock type
Other rock types
Lithologic constituents
Igneous > Hypabyssal > Felsic-hypabyssal
Igneous > Volcanic > Felsic-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.
Counties Brewster - Presidio - Reeves