IRONDALE 7.5-MINUTE QUADRANGLE and CROSS SECTION, JEFFERSON COUNTY, ALABAMA by W

GEOLOGICAL SURVEY OF ALABAMA QUADRANGLE SERIES MAP 26 PLATE 2 EXPLANATION FOR GEOLOGIC MAP AND CROSS SECTION SYMBOLS FOR GEOLOGIC MAP Contact, located very approximately, showing location of control point Horizontal beds (contact exposed or closely located) Red Mountain Formation. Dark-purplish-red, dark-reddish-brown, olive-gray, and light-gray, variably Srm ferruginous and fossiliferous, fine- to medium-grained sandstone interbedded with shale and lesser Qal Alluvium. Unconsolidated quartz silt, sand, and gravel containing clasts of local bedrock. siltstone, with minor pebbly sandstone and fossiliferous limestone to oolitic ironstone. Thrust fault, located approximately, sawteeth on upper plate Vertical beds SILURIAN QUATERNARY Overturned beds Thrust fault, located very approximately, sawteeth on upper plate 75 Pottsville Formation undifferentiated. Dark-gray silty shale containing intervals of light- to medium- Ppv gray lithic sandstone and interbeds of coal and underclay. Sequatchie Formation and Chickamauga Limestone undifferentiated. Red-brown to blue-gray, laminated, D Normal fault, located approximately, D on downthrown block and Anticline, showing trace and direction of plunge thin- to medium-bedded bioclastic limestone alternating with minor green-gray sandstone (Sequatchie); light-gray, U U on upthrown block where known Osc laminated to bioturbated, variably fossiliferous limestone, calcareous siltstone, calcareous shale, and minor Ppvc Chestnut Sandstone Member. Medium-gray, fine- to medium-grained lithic sandstone. greenish-gray bentonite (Chickamauga). D Normal fault, located very approximately, D on downthrown block and Overturned anticline, showing trace and direction of plunge ORDOVICIAN U U on upthrown block where known Knox Group undifferentiated. Light- to medium-gray, laminated, finely crystalline cherty dolomite and light- OCk Pine Sandstone Member. Light-gray, fine- to medium-grained quartzose sandstone containing a few, Contact or fault, concealed beneath mapped units Syncline, showing trace and direction of plunge Ppvp bluish-gray to medium-gray limestone and limy dolomite; produces abundant, primarily dense, chert residuum. thin shale-dominated intervals. Copper Ridge Dolomite. Light- to medium-gray, laminated to stromatolitic, finely crystalline cherty dolomite; Ccr Strike and dip of beds Overturned syncline, showing trace and direction of plunge Shades Sandstone Member. Very-light to light-gray, fine-grained, quartzose sandstone containing produces abundant dense, stromatolitic chert residuum. 45 Ppvs rare quartz pebbles. KNOX GROUP POTTSVILLE FORMATION LOWER PENNSYLVANIAN Parkwood Formation. Medium- to dark-gray shale containing intervals of light- to medium-gray lithic UPPER PMpw sandstone and rare limestone and coal. CAMBRIAN Ck Ketona Dolomite. Light- to medium-gray, thick-bedded, finely to coarsely crystalline dolomite. SYMBOLS FOR CROSS SECTION A-A' Floyd Shale and Bangor Limestone undifferentiated. Dark-gray to black shale containing siderite Mfb nodules (Floyd); medium-gray bioclastic and oolitic limestone (silicified near surface) containing Stratigraphic contact intervals of olive-gray and grayish-red-purple mudstone (Bangor). Fault, showing relative movement Hartselle Sandstone. Very light-gray, thin- to thick-bedded quartzose sandstone with minor interbeds Mh to intervals of dark-gray noncalcareous shale. Conasauga Formation. Lowest exposed part interbedded dark-gray shale and micritic limestone; middle and Cc upper parts include dark-gray stylonodular, bioclastic, and oolitic limestone; upper part dolomitic. Mpm Pride Mountain Formation. Dark-gray shale containing minor laminae and intervals of sandstone. Rome Formation. Grayish-red-purple and grayish-olive mudstone, shale, and siltstone containing interbedded Cr MISSISSIPPIAN sandstone, dolomite, and limestone. Tuscumbia Limestone, Fort Payne Chert, and Maury Formation undifferentiated. Dark-gray, MIDDLE TO medium- to thick-bedded, fossiliferous, sparry limestone (silicified near surface) with minor shale and Mtfpm chert (Tuscumbia); light-gray, thin- to medium-bedded, variably fossiliferous chert with partings and UPPER CAMBRIAN interbeds of shale (Fort Payne); dark-brown to greenish-gray and purplish-red, phosphatic(?) clay shale to mudstone (Maury). A CROSS SECTION A-A' A' Birmingham anticlinorium Cahaba synclinorium Blount Mountain syncline Airport anticline Jones Valley fault Hogpen Branch fault Little Cahaba syncline Helena fault Airport Highlands Jones Valley Red Mountain Shades Valley Shades Mountain Flat Ridge Cahaba River Village Creek Mtfpm Mpm Mh Ppvs Ppv Ppv Ppvc Ppvc Ppvc Ppv Ppv Cr Ppv Ppvs (Feet) 500 500 (Feet) Ppv OCk Ck OCk Ppv Ppvp (Sea Level) 0 Ppv Ppv 0 (Sea Level) -500 -500 PMpw -1,000 Cc Ck Ccr Osc Srm Mfb PMpw Ppvp -1,000 Cc Cc -1,500 -1,500 Cc Cc PMpw -2,000 PMpw -2,000 Cc Cc Ppvp -2,500 -2,500 Scale 1:24,000 No vertical exaggeration CROSS SECTION A-A' AND EXPLANATION FOR THE GEOLOGIC MAP OF THE IRONDALE 7.5-MINUTE QUADRANGLE AND CROSS SECTION, JEFFERSON COUNTY, ALABAMA By W. Edward Osborne and Andrew K. Rindsberg Berry H. (Nick) Tew, Jr. 2003 State Geologist.

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