Geologic units in Cherokee county, Alabama

Additional scientific data in this geographic area

Conasauga Formation (Cambrian) at surface, covers 28 % of this area

Light to dark-gray finely to coarsely crystalline, medium to thick-bedded dolomite containing minor greenish-gray shale and light-bluish-gray chert. In the Columbiana area of Shelby County, the Conasauga is dominated by thin to medium-bedded, dark-gray dolomitic limestone and minor dark-gray shale. In Bibb County and southwestern Shelby County, the Conasauga consists of medium-bluish-gray fine-grained, thin-bedded argillaceous limestone and interbedded dark-gray shale. In the eastern Valley and Ridge the lower part includes dark-green to pale-olive fossiliferous shale with a few dark-gray limestone interbeds.

Knox Group undifferentiated in part (Ordovician-Cambrian) at surface, covers 23 % of this area

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

Pottsville Formation (Pennsylvanian) at surface, covers 13 % 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.

Alluvial, coastal and low terrace deposits (Holocene) at surface, covers 10 % of this area

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.

High terrace deposits (Pleistocene) at surface, covers 4 % of this area

Varicolored lenticular beds of poorly sorted sand, ferruginous sand, silt, clay, and gravelly sand. Sand consists primarily of very fine to very coarse poorly sorted quartz grains; gravel composed of quartz, quartzite, and chert pebbles.

Weisner and Wilson Ridge Formations undifferentiated (Cambrian) at surface, covers 3 % of this area

Interbedded quartzose to slightly feldspathic sandstone and laterally continous conglomerate in ledge-forming units seperated by greenish-gray silty mudstone.

Red Mountain Formation (Silurian) at surface, covers 3 % 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.

Chickamauga Limestone (Ordovician) at surface, covers 2 % 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.

Floyd Shale (Mississippian) at surface, covers 2 % of this area

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.

Conasauga Formation (Cambrian) at surface, covers 2 % of this area

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

Sequatchie Formation (Ordovician) at surface, covers 1 % of this area

Light-olive-gray and dusky-red calcareous shale interbedded with light to dark-gray fine to coarse-grained partly bioclastic, argillaceous, locally glauconitic limestone.

Bangor and Monteagle Limestones undivided in part (Mississippian) at surface, covers 1 % of this area

Bangor Limestone -- medium-gray bioclastic and oolitic limestone, containing interbeds of dusky-red and olive-green mudstone in upper part. Monteagle Limestone -- light-gray oolitic limestone containing interbedded argillaceous, bioclastic, or dolomitic limestone, dolomite, and medium-gray shale.

Shady Dolomite (Cambrian) at surface, covers 1 % of this area

Bluish-gray or pale-yellowish-gray thick-bedded siliceous dolomite; characterized by coarsely crystalline porous chert.

Red Mountain Formation (Silurian) at surface, covers 1 % of this area

Dark-reddish-brown to olive-gray partly fossiliferous, mostly fine-grained sandstone interbedded with siltstone and shale; minor amounts of bioclastic limestone and conglomerate sandstone; includes hematitic beds and beds of ferruginous sandstone, outcrops in northeastern AL are finer grained and include more limestone.

Athens Shale (Ordovician) at surface, covers 0.8 % of this area

Black graptolitic shale, locally contains interbedded dark-gray limestone.

Parkwood and Pennington Formations (Pennsylvanian-Mississippian) at surface, covers 0.8 % 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.

Tuscumbia Limestone and Fort Payne Chert undifferentiated (Mississippian) at surface, covers 0.7 % of this area

Tuscumbia Limestone -- light to dark-gray fossiliferous and oolitic partly argillaceous and cherty limestone. Apparently present only along part of the northwest limb of the Coosa synclinorium. Fort Payne Chert -- dark-gray to light-gray limestone with abundant irregular light-gray chert nodules and beds. Commonly present below the Fort Payne is greenish-gray to grayish-red phosphatic shale (Maury Formation) which is mapped with the Tuscumbia Limestone and Fort Payne Chert undifferentiated.

Tuscumbia Limestone and Fort Payne Chert undifferentiated (Mississippian) at surface, covers 0.6 % of this area

Tuscumbia Limestone -- light to dark-gray fossiliferous and oolitic partly argillaceous and cherty limestone, absent locally and too thin to map seperately. Fort Payne Chert -- dark-gray to light-gray limestone with abundant irregular light-gray chert nodules and beds. Commonly present below the Fort Payne is greenish-gray to grayish-red phosphatic shale (Maury Formation) which is mapped with the Tuscumbia Limestone and Fort Payne Chert undifferentiated.

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

Massive to laminated greenish-gray and black micaceous mudstone containing minor interbeds of siltstone and very fine-grained sandstone.

Frog Mountain Sandstone (Devonian) at surface, covers 0.5 % of this area

Light to dark-gray sandstone with thin dark-gray shale interbeds, light-gray to black dolomudstone, glauconitic limestone, and fossiliferous chert locally in lower part.

Parkwood Formation and Floyd Shale undifferentiated (Pennsylvanian-Mississippian) at surface, covers 0.4 % 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. 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.

Chilhowee Group undifferentiated (Cambrian) at surface, covers 0.4 % of this area

Light to medium-gray arkose, arkosic conglomerate, and discontinous mudstone overlain by greenish-gray mudstone with minor siltstone and sandstone; dominantly light-gray pebbly quartzose sandstone in upper part.

Rome Formation (Cambrian) at surface, covers 0.3 % of this area

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

Attalla Chert Conglomerate Member of the Chickamauga Limestone (Ordovician) at surface, covers 0.2 % 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.

Sequatchie Formation, Colvin Mountain Sandstone, Greensport Formation undifferentiated (Ordovician) at surface, covers 0.2 % of this area

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 (Scraper Mountain) and in the structurally complex area at the east end of Dry Creek Mountain.

Little Oak and Lenoir Limestones undifferentiated (Ordovician) at surface, covers 0.1 % of this area

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 seperated by a tongue of the Athens 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.

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

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

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

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.

Newala Limestone (Ordovician) at surface, covers < 0.1 % of this area

Light to dark-gray thick-bedded micritic and peloidal limestone and minor dolomite.

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

Dark-gray shale and mudstone, locally containing thin interbeds and lenses of dark-greenish-gray sandstone includes probable Floyd Shale in area east of Gadsden, Etowah County.

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

Knox Group undifferentiated

Frog Mountain (Devonian) at surface, covers < 0.1 % of this area

Frog Mountain

Newala Limestone (Ordovician) at surface, covers < 0.1 % of this area

Newala Limestone

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

Pennsylvanian undifferentiated

Chickamauga Group; Middle Ordovician rocks; Rockmart Slate (Middle Ordovician) at surface, covers < 0.1 % of this area

Chickamauga Group; Middle Ordovician rocks; Rockmart Slate

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