Geologic units in DeKalb county, Alabama

Additional scientific data in this geographic area

Pottsville Formation (Pennsylvanian) at surface, covers 74 % of this area

Light-gray thin to thick-bedded quartzose sandstone and conglomerate containing interbedded dark-gray shale, siltstone, and coal. Mapped on Lookout Mountain, Blount and Chandler Mountains, and Sand Mountain northeats of Blount County, and on the mountains of Jackson, Marshall and Madison Counties north and west of the TN river.

Knox Group undifferentiated (Ordovician-Cambrian) at surface, covers 7 % of this area

Light-gray to light-brown locally sandy dolomite, dolomitic limestone, and limestone; characterized by abundant light-colored chert.

Bangor Limestone (Mississippian) at surface, covers 3 % of this area

Medium-gray bioclastic and oolitic limestone, containing interbeds of dusky-red and olive-green mudstone in upper part.

Chickamauga Limestone (Ordovician) at surface, covers 3 % of this area

Medium to dark-gray thick to thin-bedded partly argillaceous, locally fossiliferous limestone. Restricted to the western part of the Valley and Ridge province and Murphrees Valley and Wills Valley anticlines. Locally includes a thin interval of Attalla Chert Conglomerate Member at base. Attalla Chert Conglomerate - conglomerate of pebbles, cobbles, and boulders of chert and rare dolomite and quartzite in a sand-sized matrix; thin beds of gray-green or dusky-red shale common at base.

Parkwood and Pennington Formations undifferentiated (Pennsylvanian-Mississippian) at surface, covers 3 % of this area

Interbedded medium to dark-gray shale and light to medium-gray sandstone, locally contains lithic conglomerate, dusky-red and grayish-green mudstone, argillaceous limestone, and clayey coal.

Monteagle Limestone (Mississippian) at surface, covers 3 % of this area

Light-gray oolitic limestone containing interbedded argillaceous, bioclastic, or dolomitic limestone, dolomite, and medium-gray shale.

Tuscumbia Limestone and Fort Payne Chert undivided (Mississippian) at surface, covers 3 % of this area

Tuscumbia Limestone -- light-gray partly oolitic limestone; very coarse bioclastic crinoidal limestone common; light-gray chert nodules and concretions locally abundant. Fort Payne Chert -- very light to light-olive-gray, thin to thick-bedded fine to coarse-grained bioclastic (abundant pelmatozoans) limestone containing abundant nodules, lenses and beds of light to dark-grey chert. Upper part of formation locally consists of light-bluish-gray laminated siltstone containing vugs lined or filled with quartz and scattered throughout the formation are interbeds of medium to greenish-gray shale, shaly limestone and siltstone. Lenses of dark-gray siliceous shale occur locally at the base of the Fort Payne in Wills Valley. Commonly present below the Fort Payne is a ligh-olive-gray claystone or shale (Maury Formation) which is mapped with the Fort Payne. The Tuscumbia and Fort Payne are undifferentiated in Murphrees and Wills Valleys.

Red Mountain Formation (Silurian) at surface, covers 2 % of this area

Interbedded yellowish-gray to moderate-red sandstone, siltstone and shale; greenish-gray to moderate-red fossiliferous partly silty and sandy limestone; few thin hematitic beds.

Sequatchie Formation (Ordovician) at surface, covers 2 % of this area

Grayish-red, grayish-green, and yellowish-gray thin-bedded calcareous shale and calcareous mudstone containing interbedded fossiliferous limestone, and medium-gray to moderate-red partly sandy and glauconitic, medium to coarse-grained bioclastic limestone. In Jackson County, includes the Leipers Limestone and Inman Formation.

Pennington Formation (Mississippian) at surface, covers 0.1 % of this area

Medium-gray shale, containing interbedded limestone, dolomite, argillaceous sandstone, dusky-red and grayish-olive mudstone, and minor shaly coal. Mainly restricted to northeastern AL and part of the Sequatchie anticline. Where less than 100 feet thick the formation is included in the Bangor Limestone.

Pennsylvanian undifferentiated (Pennsylvanian) at surface, covers < 0.1 % of this area

Pennsylvanian undifferentiated

Lookout Sandstone; Sewanee Sandstone (Pennsylvanian) at surface, covers < 0.1 % of this area

Lookout Sandstone; Sewanee Sandstone

Lookout Sandstone; Gizzard Formation (Pennsylvanian) at surface, covers < 0.1 % of this area

Lookout Sandstone; Gizzard Formation

Knox Group undifferentiated (Ordovician-Cambrian) at surface, covers < 0.1 % of this area

Knox Group undifferentiated

Chickamauga Group undivided (Ordovician) at surface, covers < 0.1 % of this area

Chickamauga Group undivided

Devonian-Missisippian undivided (Devonian-Mississippian) at surface, covers < 0.1 % of this area

Includes Fort Payne Chert, Chattanooga Shale in Dade Co.; Fort Payne Chert at top, Chattanooga Shale in middle and Armuchee Shale at bottom in all areas except Polk Co. and Dade Co.; Fort Payne Chert, and Armuchee Chert in Polk Co. CHATTANOOGA Shale (Dc)

Mississippian undifferentiated (Mississippian) at surface, covers < 0.1 % of this area

Includes Pennington Shale, Bangor Limestone (except in Floyd County), Hartselle Sandstone, Golconda Formation, Gasper Limestone, Ste. Genevieve Limestone and St. Louis Limestone

Red Mountain Formation (Silurian) at surface, covers < 0.1 % of this area

Red Mountain Formation