Geologic Map and Cross Section of the Cox Gap 7.5-Minute Quadrangle, St
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GEOLOGICAL SURVEY OF ALABAMA QUADRANGLE SERIES MAP 68 PLATE DESCRIPTION OF MAP UNITS Qal Alluvial deposits (Quaternary)—Unconsolidated deposits of clay, silt, sand, gravel, and cobbles. Qcol Colluvial deposits (Quaternary)—Variably sized blocks of sandstone in a sandy matrix. Paleogene deposits (Upper Paleocene and Lower Eocene)—Lower clay-sand interval PG (HYATT GAP) consists of red, maroon, and light-gray clay that is interbedded with red to yellowish-brown, fine- to coarse-grained sand locally containing maroon pisolitic (DUNAWAY bauxite. Middle sand interval is dominantly light-gray to lavender, coarse-grained (STEELE) MOUNTAIN) sand containing rare light-gray to light-red clay partings. Upper clay-lignite interval A ! \c 15073 Qal B consists of several laterally discontinuous lignite beds that are interbedded with \c ! O\k O\k " O\k maroon to light-gray, massive-bedded clay and reddish-brown sand and gravel. !15074 " 15535 Osgc Gadsden Osgc !pvu Pottsville Formation upper part (Lower Pennsylvanian)— Olive-gray to dark-gray, mushwad " O\k 14357! thin- to flaggy-bedded, fine- to coarse-grained, well-cemented, lithic sandstone and Srm siltstone. Interbedded with the sandstone is variegated reddish-brown to light-gray, Qal Rome fault " mudstone and medium- to dark-gray fissile shale and silty shale. \c ! !pvp Pottsville Formation, Pine Sandstone Member (Lower Pennsylvanian)—Pinkish-gray 13911 " Mtfpm to light-gray, thin- to massive-bedded, fine- to coarse-grained, quartzose sandstone; 14895 ª ! 4325 quartz-pebble conglomerate; and conglomeratic sandstone. \c 15268 " ª Srm !pvht Pottsville Formation, Hardwick Tunnel member (Lower Pennsylvanian)—Alternating O\k " intervals of gray, thin-bedded fine-grained, sandstone and dark-gray to black partly 15270 Rainbow City fault Srm carbonaceous mudstone and shale weathering yellowish gray to grayish orange; ! \c " locally contains rare interbeds of gray, coarse bioclastic limestone. \c Mtfpm Mh !pvs Mpm Mh ª Pottsville Formation, Shades Sandstone Member (Lower Pennsylvanian)—Very light ! 15536 ª14621 gray to light-gray, fine- to coarse-grained, quartzose sandstone; quartz-pebble " Qal Mb conglomerate; and conglomeratic sandstone. " "14620 !Mpwf!Mpwf !Mpwfb Parkwood Formation and Floyd Shale undifferentiated (Middle and Upper Mississippian)—Parkwood Formation: Light- to dark-gray shale and mudstone containing interbedded units of light-gray, brownish-gray, and medium-gray, thin- to \r massive-bedded, very fine grained, locally silty, micaceous sandstone. Floyd Shale: \c Dark-gray to black partly sideritic shale. Bangor Limestone tongue in Floyd Shale \c Mh (!Mpwfb): Dark-gray, thin-bedded, partly laminated chert that weathers yellowish Qal green and interbedded dark-gray shale. Mb Bangor Limestone (Upper Mississippian)—Bioclastic and oolitic limestone that locally includes micritic and argillaceous limestone, shale, mudstone, and dolomite Mb weathering to yellowish-tan to grayish-orange, vuggy to locally grainy, fossiliferous Dunaway Mountain fault chert containing abundant pelmatozoan and bryozoan fossils. Mhpm Hartselle Sandstone and Pride Mountain Formation undifferentiated (Middle and \c O\k O\chcr Upper Mississippian)—Hartselle Sandstone: Pinkish-gray to light-medium-gray, thin- to flaggy-bedded, very fine to locally medium-grained, friable, quartzose Mh Qal O\chcr sandstone that weathers grayish orange and orange brown. Few interbeds of dark-gray Qal shale. Pride Mountain Formation: Grayish-orange-pink to moderate-orange-pink, thin-bedded, friable, micaceous sandstone; maroon, well-cemented siltstone; and Olv Rome fault yellowish-gray shale. Osgc Helena fault Mh Srm Qal Olv Hartselle Sandstone (Upper Mississippian)—Light-gray, pale-red, and grayish-orange, \c B' fine- to locally medium-grained, quartzose sandstone; locally contains interbeds and On intervals of grayish-orange siltstone and shale weathered olive-green and tan to grayish-orange. Qcol Olv Mpm O\k \c Olv Pride Mountain Formation (Upper Mississippian)—Medium- to dark-gray fissile clay shale containing abundant siderite nodules. O\chcr On Og Ol Mtfpm Qal Tuscumbia Limestone, Fort Payne Chert, and Maury Formation undifferentiated Olv Qal Cr Ocm (Lower and Upper Mississippian)—Tuscumbia Limestone: Bluish-gray to On Qal On medium-gray bioclastic limestone. Fort Payne Chert: Medium-gray, thin- to Srm Os medium-bedded, limey dolomite; dark-gray, dense chert; and claystone that commonly \c On Og weathers very light gray to grayish orange. Maury Formation: Pale-purple, Mtfpm Mhpm moderate-greenish-yellow, and pale-olive shale and blocky mudstone. Srm Dfm Mtfpm Og Frog Mountain Sandstone (Lower and Middle Devonian)—Medium-dark-gray to black On On Ocm shale and fine-grained, dark-greenish-brown siltstone containing olive-gray, dense \r nodules of chert. Ol Os Mhpm !Mpwfb (OHATCHEE) Srm (ASHVILLE) Qal Red Mountain Formation (Lower and Upper Silurian)—Dunaway Mountain thrust Mtfpm Srm sheet: Grayish-orange, brownish-gray, and dark-gray, thin- to medium-bedded, fine- O\chcr to very coarse grained sandstone and quartz-pebble conglomerate. Intervals of \c moderate-red to moderate-reddish-brown, thin- to medium-bedded hematitic ore and On olive-green to yellowish-green, blocky mudstone and shale are common. Helena thrust sheet: Light-brown to grayish-red, thin- to medium-bedded, fine-grained sandstone; dark-grayish-red to medium-gray, thin- to medium-bedded, pebbly sandstone; moderate-red hematitic sandstone; and light- to medium-gray and pale-red Og TuPG !Mpwf shale, mudstone, and siltstone. Hebble !Mpwf Mine Ol Oscg Mhpm Sequatchie Formation, Greensport Formation, and Chickamauga Limestone Olv Srm undifferentiated (Middle and Upper Ordovician)—Sequatchie Formation: On !Mpwfb Interbedded reddish-gray and yellowish-gray to greenish-gray, very fine-grained On sandstone; calcareous siltstone; and light-greenish-gray, medium-bedded, Os Qal !Mpwf Qal Ocm !Mpwf fine-crystalline dolomite. Greensport Formation: Lower part consists of mottled !pvs !Mpwf pale-red, grayish-red, and moderate olive-brown, thin- to medium-bedded, Mhpm Qal !pvs argillaceous limestone; grayish-red to olive-gray, very fine grained sandstone; and Mtfpm brownish-gray, fine-crystalline dolomite. Upper part consists of interbedded !pvs !pvht medium-gray to maroon, thin- to flaggy-bedded, siliceous dolomite and medium- to dark-gray micritic limestone locally containing mottled grayish-red to olive-green, On !pvp very fine grained sandstone and siltstone. Chickamauga Limestone: Medium- to Ol Dfm greenish-gray, thin- to medium-bedded, fine-grained limestone locally containing Og Qal white to dark-gray chert clasts, and olive-gray shale. Chert-pebble conglomerate and !Mpwf breccia locally at base (Attala Chert Conglomerate Member). !pvht Os Sequatchie Formation (Upper Ordovician)—The lower part is interbedded !Mpwfb !Mpwf grayish-yellow-green to pale-yellowish-green, thin-bedded, fine-crystalline dolomite; Mhpm !pvs !pvu !pvp Dfm medium- to dark-gray bioclastic limestone; and olive-green to maroon mudstone. The !Mpwf upper part consists of interbedded, mottled, pale-red and pale-olive-green, silty !Mpwf !Mpwf mudstone; olive-green siltstone; grayish-red, dolomitic siltstone; and medium-gray, !pvht !Mpwf Qal fine-crystalline dolomite. !pvu !Mpwf Ocm Colvin Mountain Sandstone (Middle Ordovician)—Very light gray to light-brown, fine- !Mpwf to coarse-grained, quartzose sandstone. Locally, bentonite clay containing euhedral !Mpwf !pvu biotite is present. Qal !pvp !pvp !pvu Og Greensport Formation (Middle Ordovician)—Predominantly maroon and greenish-gray, blocky mudstone, shale, and mottled dolomite. !pvs !pvu Fairview fault !pvht Ol Lenoir Limestone (Lower Ordovician)—Medium- to medium-dark-gray, thin- to thick-bedded, argillaceous, stylonodular limestone. The upper part of the Lenoir consists of medium-gray, thin- to massive-bedded, argillaceous limestone and locally, !pvp light-gray, fenestral lime mudstone. Greenish-gray, and light- to dark-gray, dominantly thick-bedded, dense, fenestral limestone in lower part (Mosheim !pvp Limestone Member). On !pvu Newala Limestone (Lower Ordovician)—Light- to medium-bluish-gray, thin- to massive-bedded, partly fenestral, fossiliferous, micritic limestone locally containing Fairview syncline !pvu interbeds of light- to light-bluish-gray, thin- to thick-bedded, fine- to medium-crystalline dolomite and dolomottled limestone. Olv Longview Limestone (Lower Ordovician)—Interbedded light- to light-medium-gray, !pvu !pvu !pvu thin- to medium-bedded, micritic limestone; light-gray, medium-crystalline dolomite; and light- to medium-gray, thin-bedded chert. Longview residuum consists of white to !pvu Qal pale-yellowish-orange, rounded, nodular, and bedded partly fossiliferous, locally Coosa synclinorium A' peloidal, dense chert. Thin sandstone beds, as well as chert beds containing (RAGLAND) (FRANCIS MILL) disseminated quartz sand, are locally present. Base topographic map U.S. Geological Survey 1958. Photorevised 1978 O\k Digital database by G. Daniel Irvin Knox Group undifferentiated (Upper Cambrian and Lower Ordovician)—Light- to MN (WATTSVILLE) 1 1/ 2 0 1 MILE QUADRANGLE LOCATION This geologic map was funded in part by the USGS GN medium-dark-gray, thin- to massive-bedded, fine- to medium-crystalline dolomite National Cooperative Geologic Mapping Program containing irregular nodules and stringers and locally thin to medium beds of light- to o 1 0 1 KILOMETER under StateMap award number G13AC00375, 2013. o .1 3.52 1.8 MILS pinkish-gray,