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Midway Group, undivided

Midway Group, undivided
State Texas
Name Midway Group, undivided
Geologic age Phanerozoic | Cenozoic | Tertiary | Paleocene
Comments clay, silty, sandy, sl. glauconitic, massive, poorly bedded, grades up to mudst. and sand of Wilcox Group; thickness 500 +-ft. Kincaid Fm- upper part (Pisgah Member) sand and clay; sand, glauconitic, poorly sorted, clayey; clay, sandy, silty, med. gray to black; lower part (Littig Member) sand and clay; sand v. glauconitic, greenish black; clay sandy, phosphatic nodules and pebbles; thickness 150 +-ft. In East Texas and Gulf Coast to Rio Grande: clay, sand, limestone, and marl 500-650 ft thick
Primary rock type fine-grained mixed clastic
Secondary rock type limestone
Other rock types mudstone
Lithologic constituents
Major
Unconsolidated > Fine-detrital > Clay (Bed)
Unconsolidated > Coarse-detrital > Sand (Bed)
Minor
Unconsolidated > Fine-detrital > Silt (Bed)
Incidental
Sedimentary > Carbonate > Marlstone (Bed)marl
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, 1974, San Antonio Sheet, Geologic Atlas of Texas, University of Texas, Bureau of Economic Geology, scale 1:250,000.
Bureau of Economic Geology, 1972, Dallas sheet, Geologic Atlas of Texas, Bureau of Economic Geology, University of Texas at Austin, scale 1:250,000.
Bureau of Economic Geology, 1974, Seguin Sheet, Geologic Atlas of Texas, University of Texas, Bureau of Economic Geology, scale 1:250,000.
Bureau of Economic Geology, 1965, Tyler sheet, Geologic Atlas of Texas, Bureau of Economic Geology, University of Texas at Austin, scale 1:250,000.
Bureau of Economic Geology, 1966, Texarkana Sheet, Geologic Atlas of Texas, University of Texas, Bureau of Economic Geology, scale 1:250,000.
Counties Bastrop - Bexar - Bowie - Caldwell - Falls - Franklin - Guadalupe - Hopkins - Medina - Milam - Red River - Titus - Williamson