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Mineral Resources > Online Spatial Data > Geology > by state > Alabama Geology

Geologic units in Saint Clair county, Alabama

[Additional scientific data in this geographic area]

Attalla Chert Conglomerate Member of the Chickamauga Limestone (Ordovician) at surface, covers < 0.1 % of this area

Attalla Chert Conglomerate Member of the Chickamauga Limestone - 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.

Lithology: conglomerate; chert; shale; dolostone (dolomite); quartzite

Chickamauga Limestone (Ordovician) at surface, covers 0.6 % of this area

Chickamauga Limestone - 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.

Lithology: limestone; conglomerate; chert; shale; dolostone (dolomite); quartzite

Pottsville Formation (Pennsylvanian) at surface, covers 3 % of this area

Pottsville Formation - 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.

Lithology: sandstone; conglomerate; shale; siltstone; coal

Sequatchie Formation, Colvin Mountain Sandstone, Greensport Formation undifferentiated (Ordovician) at surface, covers 0.1 % of this area

Sequatchie Formation, Colvin Mountain Sandstone, Greensport Formation undifferentiated - variegated dusky-red and pale-yellowish-orange shale, calcareous mudstone, dolomite, siltstone, and minor sandstone. Mapped in areas of facies transition with the Chickamauga Limestone (Canoe Creek, Dunaway, and Hensley Mountains).

Lithology: shale; mudstone; dolostone (dolomite); siltstone; sandstone

Parkwood Formation and Floyd Shale undifferentiated (Pennsylvanian-Mississippian) at surface, covers 8 % of this area

Parkwood Formation and Floyd Shale undifferentiated - Parkwood Formation -- Interbedded medium to dark-gray shale and light to medium-gray sandstone; locally contains dusky-red and grayish-green mudstone, argillaceous limestone, and clayey coal. Floyd Shale -- Dark-gray shale, sideritic in part; thin beds of sandstone, limestone and chert are locally present; beds of partly bioclastic, partly argillaceous limestone are abundant in parts of Calhoun and Cherokee Counties.

Lithology: shale; sandstone; mudstone; limestone; chert; mixed clastic/coal; clay or mud

Sequatchie Formation (Ordovician) at surface, covers 0.2 % of this area

Sequatchie Formation - 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.

Lithology: shale; mudstone; limestone

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

Red Mountain Formation - 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.

Lithology: sandstone; shale; siltstone; limestone

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

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

Lithology: limestone; mudstone

Pottsville Formation (lower part) (Pennsylvanian) at surface, covers 6 % of this area

Pottsville Formation (lower part) - Light-gray thick-bedded to massive pebbly quartzose sandstone, containing varying amounts of interbedded dark-gray shale, siltstone, and thin discontinuos coal. In both the Cahaba and Coosa synclinoria the members in descending order include: the Pine Sandstone Member and the Shades Sandstone Member. Top of unit is mapped at top of Pine Sandstone Member.

Lithology: sandstone; shale; siltstone; coal

Pottsville Formation (upper part) (Pennsylvanian) at surface, covers 22 % of this area

Pottsville Formation (upper part) - Interbedded dark-gray shale, siltstone, medium-gray sandstone, and coal in cyclic sequences. The members present in the Cahaba synclinorium in descending order include: the Straven Conglomerate Member, Rocky Ridge Sandstone Member, and Chestnut Sandstone Member. The members present in the Coosa synclinorium in descending order include: Straight Ridge Sandstone Member and Wolf Ridge Sandstone Member.

Lithology: shale; siltstone; sandstone; coal

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

Tuscumbia Limestone and Fort Payne Chert undivided - 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.

Lithology: limestone; chert; siltstone; shale; claystone

Colvin Mountain Sandstone (Ordovician) at surface, covers 0.2 % of this area

Colvin Mountain Sandstone - light-gray quartzose sandstone, pebbly in part. Locally contains thin beds of bentonite in the upper part.

Lithology: sandstone; bentonite

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

Greensport Formation - variegated dusky-red and dark-yellowish-orange shale, calcareous mudstone, limestone, siltstone, and minor sandstone.

Lithology: shale; mudstone; limestone; siltstone; sandstone

Knox Group undifferentiated (Ordovician-Cambrian) at surface, covers 13 % of this area

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

Lithology: dolostone (dolomite); limestone; chert

Floyd Shale (Mississippian) at surface, covers 4 % of this area

Floyd Shale - Dark-gray shale, sideritic in part; thin beds of sandstone, limestone and chert are locally present; beds of partly bioclastic, partly argillaceous limestone are abundant in parts of Calhoun and Cherokee Counties.

Lithology: shale; sandstone; limestone; chert

Conasauga Formation (Cambrian) at surface, covers 13 % of this area

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

Lithology: limestone; shale

Pride Mountain Formation (Mississippian) at surface, covers 2 % of this area

Pride Mountain Formation - 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.

Lithology: shale; limestone; sandstone; mudstone

Conasauga Formation, lower unnamed shale facies (Cambrian) at surface, covers 0.1 % of this area

Conasauga Formation, lower unnamed shale facies - lower unnamed shale facies in eastern Valley and Ridge consists of dark-green to pale-olive fossiliferous shale with a few dark-gray limestone interbeds.

Lithology: shale; limestone

Parkwood Formation (Pennsylvanian-Mississippian) at surface, covers 2 % of this area

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

Lithology: shale; sandstone; mudstone; limestone; clay or mud; mixed clastic/coal

Newala Limestone (Ordovician) at surface, covers 2 % of this area

Newala Limestone - light to dark-gray thick-bedded micritic and peloidal limestone and minor dolomite.

Lithology: limestone; dolostone (dolomite)

Hartselle Sandstone (Mississippian) at surface, covers 3 % of this area

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

Lithology: sandstone; shale

Ketona Dolomite (Cambrian) at surface, covers 0.1 % of this area

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

Lithology: dolostone (dolomite)

Rome Formation (Cambrian) at surface, covers 0.6 % of this area

Rome Formation - variegated thinly interbedded mudstone, shale, siltstone, and sandstone; limestone and dolomite occur locally. Quartzose sandstone commonly present near top of formation.

Lithology: mudstone; shale; siltstone; sandstone; limestone; dolostone (dolomite)

Little Oak and Lenoir Limestones undifferentiated (Ordovician) at surface, covers 2 % of this area

Little Oak and Lenoir Limestones undifferentiated - dark-gray argillaceous, fossiliferous medium to thick-bedded limestone; locally contains rare chert in upper part and an interval of fenestral mudstone in lower part (Mosheim Limestone Member of the Lenoir Limestone). Between Siluria and Pelham in Shelby County, the Little Oak and Lenoir Limestones are separated by a tongue of the Athens Shale.

Lithology: limestone; mudstone; chert

Longview Limestone (Ordovician) at surface, covers 0.9 % of this area

Longview Limestone - light to medium-gray thick-bedded cherty limestone and dolomite, locally sandy.

Lithology: limestone; dolostone (dolomite)

Parkwood and Pennington Formations undifferentiated (Pennsylvanian-Mississippian) at surface, covers 2 % of this area

Parkwood and Pennington Formations undifferentiated - 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.

Lithology: shale; sandstone; conglomerate; mudstone; limestone; clay or mud; mixed clastic/coal

Chepultepec and Copper Ridge Dolomites undifferentiated (Ordovician-Cambrian) at surface, covers 6 % of this area

Chepultepec and Copper Ridge Dolomites undifferentiated - Light-gray to dark-bluish-gray thick-bedded dolomite and interbedded light-gray limestone; includes abundant chert.

Lithology: dolostone (dolomite); limestone; chert

Alluvial, coastal and low terrace deposits (Holocene) at surface, covers < 0.1 % of this area

Alluvial, coastal and low terrace deposits - Varicolored fine to coarse quartz sand containing clay lenses and gravel in places. Gravel composed of quartz and chert pebbles and assorted metmorphic and igneous rock fragments in streams near the Piedmont. In areas of the Valley and Ridge province gravel composed of angular to subrounded chert, quartz, and quartzite pebbles. Coastal deposits include fine to medium quartz sand with shell fragments and accessory heavy minerals along Gulf beaches and fine to medium quartz sand, silt, clay, peat, mud and ooze in the Mississippi Sound, Little Lagoon, bays, lakes, streams, and estuaries.

Lithology: beach sand; alluvium