Duff Formation (with Decie Member from Paisano caldera shown separately), Cottonwood Springs Basalt, Potato Hill Andesite, Sheep Canyon Basalt, Crossen Trachyte, and Pruett Formation, undivided (TXOGEOd;0)

Duff Formation (with Decie Member from Paisano caldera shown separately), Cottonwood Springs Basalt, Potato Hill Andesite, Sheep Canyon Basalt, Crossen Trachyte, and Pruett Formation, undivided

Duff Formation (with Decie Member from Paisano caldera shown separaetly), Cottonwood Springs Basalt, Potato Hill Andesite, Sheep Canyon Basalt, Crossen Trachyte, and Pruett Formation, undivided

State	Texas
Name	Duff Formation (with Decie Member from Paisano caldera shown separately), Cottonwood Springs Basalt, Potato Hill Andesite, Sheep Canyon Basalt, Crossen Trachyte, and Pruett Formation, undivided
Geologic age	Phanerozoic \| Cenozoic \| Tertiary \| Eocene-Late Oligocene-Early
Comments	in west Brewster Co., rhyolitic tuff, minor sandstone, conglomerate and mafic flows, felsic flows, and flow breccia. mafic flows, anygdaloidal, vesicular, andesitic flow breccia, porphyritic mafic flows, thin tuff and nonmarine limestone, prophyritic quartz trachyte, tuff, tuffaceous sandstone, conglomerate breccia, tuffaceous nonmarine limestone. Pruett Fm., about 330 ft thick in Fort Stockton Sheet (1982), mostly volcanic tuff, some tuffaceous sandstone, conglo., breccia, and tuffaceous fresh-water limestone which interfingers with other units named in this map unit. Thickness more than 4,500 ft.
Primary rock type	rhyolite
Secondary rock type	basalt
Other rock types	tuff; sandstone; conglomerate; limestone
Lithologic constituents	Major Igneous > Volcanic > Felsic-volcanic > Rhyolite (Pyroclastic, ash-flow) Minor Igneous > Volcanic > Mafic-volcanic > Basalt Igneous > Volcanic > Felsic-volcanic > Trachyte Sedimentary > Clastic > Mixed-clastic > Siltstone-Mudstone Incidental Sedimentary > Carbonate > Limestone (Tuffaceous) Sedimentary > Clastic > Sandstone (Tuffaceous) Sedimentary > Clastic > Conglomerate (Tuffaceous)
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, 1982, Fort Stockton Sheet, Geologic Atlas of Texas, University of Texas at Austin, scale 1:250,000. Bureau of Economic Geology, 1979, Emory Peak--Presidio Sheet, Geologic Atlas of Texas, University of Texas at Austin.
Counties	Brewster - Jeff Davis - Presidio

State

Texas

Name

Duff Formation (with Decie Member from Paisano caldera shown separately), Cottonwood Springs Basalt, Potato Hill Andesite, Sheep Canyon Basalt, Crossen Trachyte, and Pruett Formation, undivided

Geologic age

Phanerozoic | Cenozoic | Tertiary | Eocene-Late Oligocene-Early

Comments

in west Brewster Co., rhyolitic tuff, minor sandstone, conglomerate and mafic flows, felsic flows, and flow breccia. mafic flows, anygdaloidal, vesicular, andesitic flow breccia, porphyritic mafic flows, thin tuff and nonmarine limestone, prophyritic quartz trachyte, tuff, tuffaceous sandstone, conglomerate breccia, tuffaceous nonmarine limestone. Pruett Fm., about 330 ft thick in Fort Stockton Sheet (1982), mostly volcanic tuff, some tuffaceous sandstone, conglo., breccia, and tuffaceous fresh-water limestone which interfingers with other units named in this map unit. Thickness more than 4,500 ft.

Primary rock type

rhyolite

Secondary rock type

basalt

Other rock types

tuff; sandstone; conglomerate; limestone

Lithologic constituents

Major

Igneous > Volcanic > Felsic-volcanic > Rhyolite (Pyroclastic, ash-flow)

Minor

Igneous > Volcanic > Mafic-volcanic > Basalt

Igneous > Volcanic > Felsic-volcanic > Trachyte

Sedimentary > Clastic > Mixed-clastic > Siltstone-Mudstone

Incidental

Sedimentary > Carbonate > Limestone (Tuffaceous)

Sedimentary > Clastic > Sandstone (Tuffaceous)

Sedimentary > Clastic > Conglomerate (Tuffaceous)

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, 1982, Fort Stockton Sheet, Geologic Atlas of Texas, University of Texas at Austin, scale 1:250,000.

Bureau of Economic Geology, 1979, Emory Peak--Presidio Sheet, Geologic Atlas of Texas, University of Texas at Austin.

Counties

Brewster - Jeff Davis - Presidio