Blackwater Draw Formation (TXQbd;0)

State	Texas
Name	Blackwater Draw Formation
Geologic age	Phanerozoic \| Cenozoic \| Quaternary \| Pleistocene
Original map label	Qbd
Comments	Sand, fine- to medium-grained quartz, silty, calcareous, locally clayey, caliche nodules, massive, grayish red; distinct soil profile; thickness as much as 25 ft. feathers out locally.
Primary rock type	sand
Secondary rock type	silt
Other rock types	clay or mud
Lithologic constituents	Major Unconsolidated > Coarse-detrital > Sand (Bed) Minor Unconsolidated > Fine-detrital (Bed) Incidental Unconsolidated > Fine-detrital > Silt (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, 1977, Clovis Sheet, Geologic Atlas of Texas, Bureau of Economic Geology, University of Texas at Austin, scale 1:250,000. Bureau of Economic Geology, 1983, Tucumcari Sheet, Geologic Atlas of Texas, Bureau of Economic Geology, University of Texas at Austin, scale 1:250,000.
Geographic coverage	Andrews - Armstrong - Bailey - Borden - Briscoe - Carson - Castro - Cochran - Crane - Crosby - Dallam - Dawson - Deaf Smith - Dickens - Donley - Ector - Floyd - Gaines - Garza - Glasscock - Gray - Hale - Hansford - Hartley - Hemphill - Hockley - Howard - Hutchinson - Lamb - Lipscomb - Lubbock - Lynn - Martin - Midland - Moore - Motley - Ochiltree - Oldham - Parmer - Potter - Randall - Reagan - Roberts - Sherman - Sterling - Swisher - Terry - Upton - Wheeler - Winkler - Yoakum