Navarro Group and Marlbrook Marl, undivided

Navarro Group and Marlbrook Marl, undivided
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