Geologic units in Blount county, Alabama

Pottsville Formation (lower part) (Pennsylvanian) at surface, covers 56 % of this area

Light-gray thick-bedded to massive pebbly quartzose sandstone, containing varying amounts of interbedded dark-gray shale, siltstone, and thin discontinuos coal. The Boyles Sandstone Member is a formally named unit in the lower part of the formation. Top of unit is mapped at the Black Creek coal.

Pottsville Formation (Pennsylvanian) at surface, covers 14 % 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.

Bangor Limestone (Mississippian) at surface, covers 6 % of this area

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

Tuscumbia Limestone and Fort Payne Chert undivided (Mississippian) at surface, covers 6 % 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.

Chepultepec and Copper Ridge Dolomites undifferentiated (Ordovician-Cambrian) at surface, covers 4 % of this area

Light-gray to dark-bluish-gray thick-bedded dolomite and interbedded light-gray limestone; includes abundant chert.

Hartselle Sandstone (Mississippian) at surface, covers 4 % of this area

Light-colored thick-bedded to massive quartzose sandstone, containing interbeds of dark-gray shale.

Pride Mountain Formation (Mississippian) at surface, covers 3 % of this area

Medium to dark-gray shale, containing one to three units of a variable combination of sandstone and limestone in the lower part; locally contains rare interbeds of dusky-red and greenish-gray mudstone.

Pottsville Formation (upper part) (Pennsylvanian) at surface, covers 1 % of this area

Interbedded dark-gray shale, siltstone, medium-gray sandstone, and coal in cyclic sequences. In descending order the members include: Razburg Sandstone Member, Camp Branch Sandstone Member, Lick Creek Sandstone Member, and the Bremen Sandstone Member.

Red Mountain Formation (Silurian) at surface, covers 1 % 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.

Conasauga Formation (Cambrian) at surface, covers 0.8 % of this area

Medium-bluish-gray fine-grained, thin-bedded argillaceous limestone and interbedded dark-gray shale in varying proportions.

Chickamauga Limestone (Ordovician) at surface, covers 0.8 % 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.

Sequatchie Formation (Ordovician) at surface, covers 0.6 % 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.

Parkwood and Pennington Formations undifferentiated (Pennsylvanian-Mississippian) at surface, covers 0.5 % 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.

Leipers Limestone (Ordovician) at surface, covers 0.4 % of this area

Leipers Limestone -- medium to dark-gray thin to medium-bedded fossiliferous limestone containing interbeds of thin argillaceous limestone. Mapped in Sequatchie Valley. Inman Formation -- interbedded greenish-gray or moderate to dusky-red shale and light-gray peloidal limestone. Mapped in Sequatchie Valley.

Inman Formation (Ordovician) at surface, covers 0.4 % of this area

Interbedded greenish-gray or moderate to dusky-red shale and light-gray peloidal limestone. Mapped in Sequatchie Valley.

Attalla Chert Conglomerate Member of the Chickamauga Limestone (Ordovician) at surface, covers 0.4 % of this area

Conglomerate of pebbles, cobbles, and boulders of chert and rare dolomite and quartzite in a sand-sized chert and quartz matrix; thin beds of gray-green or dusky-red shale common at base.

Parkwood and Pennington Formations (Pennsylvanian-Mississippian) at surface, covers 0.4 % 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.

Pennington Formation (Mississippian) at surface, covers 0.3 % 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.

Ketona Dolomite (Cambrian) at surface, covers 0.3 % of this area

Light to medium-gray thick-bedded coarsely crystalline dolomite.

Nashville and Stones River Groups undifferentiated (Ordovician) at surface, covers 0.1 % of this area

Medium to dark-gray fossiliferous limestone, argillaceous in part; yellowish-gray laminated silty limestone in upper part. Contains one or more thin beds of bentonite and bentonitic shale.

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

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