Catahoula Formation (TXOGc;0)

State	Texas
Name	Catahoula Formation
Geologic age	Phanerozoic \| Cenozoic \| Tertiary \| Oligocene
Original map label	Oc
Comments	Crystal City-Eagle Pass Sheet (1976), upper member, Chusa Tuff Mbr is tuffaceous mudstone and sand and sandstone about 180 ft thick. next member descending is Soledad Volcanic Conglo. Mbr, abdt. pebbles, cobbles, and boulders up to one foot in size, rhyolite, trachyte, trachyandesite, thickness up to 75 ft; Fant Tuff Mbr, lowest mbr., tuff, claystone, and sandstone about 600 ft thick. Catahoula Fm. 120-300 ft thick on Seguin Sheet (1974) thins northward. In East Texas and Gulf Coast to Rio Grande: Mudstone and sand. Upper 300-500 ft mudst., tuffaceous, sandy, lt. gray, weathers dk gray. Some bentonitic clay. Lower 10-80 ft quartz sand, coarse grained, grains polished, opal cement common; fossil wood abdt. forms cuesta. Thickness 300-600 ft.
Primary rock type	mudstone
Secondary rock type	sand
Other rock types	tuff; sandstone; conglomerate
Lithologic constituents	Major Unconsolidated > Coarse-detrital > Sand (Bed) Sedimentary > Clastic > Mudstone (Bed) Minor Sedimentary > Clastic > Conglomerate (Bed) Incidental Igneous > Volcanic > Felsic-volcanic > Rhyolite Igneous > Volcanic > Felsic-volcanic > Trachyte Igneous > Volcanic > Mafic-volcanic > Andesite (Pyroclastic, tuff) Sedimentary > Clastic > Mudstone > Claystone > Bentonite (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, 1976, Crystal City-Eagle Pass Sheet, Geologic Atlas of Texas, University of Texas, Bureau of Economic Geology, scale 1:250,000. Bureau of Economic Geology, 1967, Palestine Sheet, Geologic Atlas of Texas, Bureau of Economic Geology, University of Texas at Austin, scale 1:250,000.
Geographic coverage	Angelina - Atascosa - Bee - Brazos - DeWitt - Duval - Fayette - Gonzales - Grimes - Jasper - Karnes - Lavaca - Live Oak - McMullen - Newton - Polk - Sabine - Trinity - Tyler - Walker - Washington - Webb