| State | Texas |
|---|---|
| Name | Navarro Group and Marlbrook Marl, undivided |
| Geologic age | Late Cretaceous; Gulfian Series |
| Lithologic constituents |
Major
Sedimentary > Clastic > Mixed-clastic > Siltstone-mudstone (Bed)
Unconsolidated > Fine-detrital > Clay (Bed)
Minor
Sedimentary > Clastic > Sandstone (Bed)
Incidental
Sedimentary > Carbonate > Limestone (Bed)
|
| Comments | Clay, calcareous, variable amount of silt and glauconite, limestone bed in so. Collin Co. 10-13 inches thick, aphanitic, lt. gray, forms scarp 180 ft above base; light yell-gray, marine megafossils, thickness 300 +- ft. Upper 250 ft, mostly silty, calcar. clay with sandst beds and concretionary masses near top, some interbeds of sandst. near base. Lower 200+- ft, quartz sand, fine grained, silty, locally calcar. concretions in discontin. beds, lt. gray; marine megafossils. On Sherman Sheet (1967) east of Sabine River. |
| References | 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, 1967, Sherman Sheet, Geologic Atlas of Texas: University of Texas at Austin, Bureau of Economic Geology, scale 1:250,000.Bureau of Economic Geology, 1974, Austin Sheet, Geologic Atlas of Texas, University of Texas, Bureau of Economic Geology, scale 1:250,000.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. |
| NGMDB product | |
| Counties | Bastrop - Bell - Bexar - Caldwell - Falls - Guadalupe - Hays - Milam - Travis - Williamson |