Ojinaga Formation (TXKoj;0)

State	Texas
Name	Ojinaga Formation
Geologic age	Phanerozoic \| Mesozoic \| Cretaceous-Late
Original map label	Koj
Comments	in Quitman Mtns, shale, black, fissile; few beds of ss and ls, thickness 2,000+ ft. In Eagle Mtns area, shale, brown and black, fissile, calcareous, in part sandy. Sandst. calcar. grayish orange, lower 150 ft mostly ls, microgranular, flaggy, fossilif. thickness 840+ft.
Primary rock type	shale
Secondary rock type	sandstone
Other rock types	limestone
Lithologic constituents	Major Sedimentary > Clastic > Mudstone > Shale > Black-shale (Bed) Minor Sedimentary > Clastic > Sandstone (Bed) Incidental Sedimentary > Carbonate > Limestone (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, Marfa Sheet, Geologic Atlas of Texas: Bureau of Economic Geology and The University of Texas at Austin, scale 1:250,000.
Geographic coverage	Culberson - Hudspeth - Jeff Davis - Presidio