San Miguel Formation (TXKsm;0)

State	Texas
Name	San Miguel Formation
Geologic age	Phanerozoic \| Mesozoic \| Cretaceous-Late [Gulfian]
Original map label	Ksm
Comments	Sandstone, limestone, and clay; fossilif. sand, sandy ls., and unfossilif. clay superficially like the underlying Upson, clay increases in amount upward; fossils include Exogyra ponderosa and many other marine megafossils; thickness about 400 ft in Crystal City-Eagle Pass area, 800 ft in Del Rio area.
Primary rock type	sandstone
Secondary rock type	limestone
Other rock types	clay or mud
Lithologic constituents	Major Sedimentary > Clastic > Sandstone (Bed) Minor Sedimentary > Carbonate > Limestone (Bed) Unconsolidated > Fine-detrital > Clay (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, 1977, Del Rio Sheet, Geologic Atlas of Texas, University of Texas, Bureau of Economic Geology, scale 1:250,000.
Geographic coverage	Kinney - Maverick