Fort Worth Limestone and Duck Creek Formation, undivided (TXKfd;0)

State	Texas
Name	Fort Worth Limestone and Duck Creek Formation, undivided
Geologic age	Phanerozoic \| Mesozoic \| Cretaceous-Early
Original map label	Kfd
Comments	Fort Worth Limestone, limestone and clay. Ls aphanitic to biosparite, burrowed; marine megafossils are Pecten, oysters, echinoids, and ammonites. Clay, calcareous, in units 0.1-5 ft thick, forms low rolling hills. Thickness 25-35 ft. Duck Creek Ls., limestone and marl. ls med. bedded, nodular to wavy bedded; thickness 25-30 ft.
Primary rock type	limestone
Secondary rock type	mudstone
Other rock types	clay or mud
Lithologic constituents	Major Sedimentary > Carbonate > Limestone (Bed) Minor Unconsolidated > Fine-detrital > Clay (Bed) Unconsolidated > Marl (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, 1972, Dallas sheet, Geologic Atlas of Texas, Bureau of Economic Geology, University of Texas at Austin, scale 1:250,000. Bureau of Economic Geology, 1970, Waco Sheet, Geologic Atlas of Texas, University of Texas, Bureau of Economic Geology, scale 1:250,000.
Geographic coverage	Cooke - Denton - Grayson - Montague - Tarrant - Wise