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Selma Group; Demopolis Chalk

Demopolis Chalk - (Selma Group), Light-gray to medium-light-gray compact, brittle chalk overlain by abundantly fossiliferous chalky marl, very clayey chalk, and calcareous clay (Bluffport Marl Member). In south-central Montgomery County the Demopolis is split into two eastward extending tongues by a westward-extending tongue of the Cusseta Sand Member of the Ripley Formation. The lower tongue is pale-olive to yellowish-gray silty to finely sand, micaceous, fossiliferous chalk that eastward becomes more sandy and merges with the Cusseta in central Bullock County. The upper tongue is yellowish-gray clayey, very finely sandy, micaceous chalk that merges with the Ripley in southeastern Montgomery County.
State Alabama
Name Selma Group; Demopolis Chalk
Geologic age Cretaceous
Primary rock type carbonate
Secondary rock type clay or mud
Other rock types sand
Lithologic constituents
Major
Sedimentary > Carbonate > Limestone > ChalkBrittle, clayey, sandy, fossiliferous, micaceous, chalk
Minor
Unconsolidated > Marlabundantly fossiliferous chalky marl
Unconsolidated > Fine-detrital > Clayclayey chalk, calcareous clay
Unconsolidated > Coarse-detrital > Sandvery finely to finely sandy chalk
Map references
Szabo, M. W., Osborne, E. W., Copeland, C. W. Jr., Neathery; T. L., 1988, Geologic Map of Alabama, Geological Survey of Alabama Special Map 220, scale 1:250,000.
Unit references
Szabo, M. W., Osborne, E. W., Copeland, C. W. Jr., Neathery; T. L., 1988, Geologic Map of Alabama, Geological Survey of Alabama Special Map 220, scale 1:250,000.
Counties Bullock - Crenshaw - Dallas - Greene - Hale - Lowndes - Marengo - Montgomery - Perry - Pickens - Sumter