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Oligocene Series undifferentiated
Descriptions of the units of the Oligocene Series follow in descending order. Paynes Hammock Sand - locally fossiliferous, calcareous, argillaceous medium to coarse sand; pale-blue-green clay; and thin-bedded sandy limestone; exposed at Paynes Hammock and at St. Stephens. Chickasawhay Limestone - white to yellowish-gray fossiliferous, glauconitic limestone and soft marl. Byram Formation includes three members in descending order: Bucatunna Clay Member - dark, bentonitic, carbonaceous, sparsely fossiliferous clay and greyish-yellow sand; unnamed marl member - light-grey to yellowish-grey sandy, glauconitic , fossiliferous marl; Glendon Limestone Member - irregularly indurated coquinoid and crystalline limestone, weathering to indurated rock containing large tubular cavities, locally known as 'horsebone'. Marianna Limestone - white to yellowish-grey soft, porous, very fossiliferous limestone. Forest Hill sand - dark-greenish-grey carbonaceous clay with lenses of glauconitic fossiliferous sand; extends eastward from MS into Choctaw, Clarke and Washington Counties. Red Bluff Clay - greenish-gray calcareous clay locally containing selenite crystals, yellowish-grey glauconitic, fossiliferous limestone; and light-gray silty clay with interbeds of sand (Forest Hill equivalent); from Tombigbee River eastward grades into glauconitic fossiliferous limestone equivalent to the Bumpnose Limestone. Bumpnose Limestone - very light-gray to yellowish-gray chalky, subcoquinoid, glauconitic, argillaceous, fossiliferous limestone; intertongues with Red Bluff Clay in vicinity of the Alabama River and is readily differentiated eastward from the Sepulga River.
State |
Alabama |
Name |
Oligocene Series undifferentiated |
Geologic age |
Oligocene |
Lithologic constituents |
Major
Sedimentary > Carbonate > Limestonewhite to yellowish-gray fossiliferous, glauconitic limestone, thin-bedded sandy limestone, irregularly indurated coquinoid and crystalline limestone
Minor
Unconsolidated > Fine-detrital > Claydark, bentonitic, carbonaceous, sparsely fossiliferous clay
Unconsolidated > Coarse-detrital > Sandlocally fossiliferous, calcareous, argillaceous medium to coarse sand; lenses of glauconitic fossiliferous sand.
Incidental
Sedimentary > Clastic > Mudstone > Claystone > Bentonitedark, bentonitic, carbonaceous, sparsely fossiliferous clay
Unconsolidated > Marllight-grey to yellowish-grey sandy, glauconitic , fossiliferous marl;
Unconsolidated > Fine-detrital > Silt
|
References |
Szabo, M.W., Osborne, E.W., Copeland, C.W. Jr., and Neathery, T.L., 1988, Geologic Map of Alabama, Geological Survey of Alabama Special Map 220, scale 1:250,000. |
NGMDB product |
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Counties |
Choctaw - Clarke - Conecuh - Covington - Escambia - Geneva - Monroe - Washington
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