Calvert Bluff Formation (TXEOPNc;0)

State	Texas
Name	Calvert Bluff Formation
Geologic age	Phanerozoic \| Cenozoic \| Tertiary \| Paleocene Eocene
Original map label	EPAc
Comments	Mostly mudstone with varing amounts of sandstone, lignite, ironstone concretions, and in uppermost part locally glauconitic. Mudst. massive to thinn bedded weathers yell-brn. Sandst. med to fine grained, mod. well sorted, crossbedded, lenticular. Lignite mostly in lower part of formation, seams 1-20 ft thick, brownish black. thickness about 1,000 ft.
Primary rock type	mudstone
Secondary rock type	sandstone
Other rock types	coal
Lithologic constituents	Major Sedimentary > Clastic > Mudstone > Claystone (Bed) Minor Sedimentary > Clastic > Sandstone (Bed) Incidental Sedimentary > Coal > Lignite (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, Austin Sheet, Geologic Atlas of Texas, University of Texas, Bureau of Economic Geology, scale 1:250,000.
Geographic coverage	Bastrop - Burleson - Falls - Freestone - Lee - Leon - Limestone - Milam - Robertson - Williamson