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System Age Formation Average Thickness (ft) Elevation near Huntsville (ft) Geologic Description Exposure Siting in Huntsville - Madison County Area
Quaternary Recent Alluvium Deposits 0-30 1560-1580 Unconsolidated sand, clay, and gravel Some evidence found in northeast Madison County atop Bingham Mountain
Pennsylvanian Pottsville Formation 85-90 1480 Sandstone, brown and gray-brown, medium to coarse grained, massive and thin bedded, contains some shale and a thin seam of coal near base. Well rounded grains. Iron containing. Top of Cumberland Plateau including Monte Sano, Green, Keel, and Wallace Mountain
Mississippian Chester Pennington Formation 80-100 1400 Shale, red, gray, and green with sand and some shaly limeston beds Thin seam found near base of sandstone caprock along Monte Sano bike trails running below the bluffs
Bangor Limestone 350-400 1000 Limestone, blue-gray, dark gray, crystalline, oolitic and partly fossiliferous, dolomitic Numerous outcroppings found at surface. Exposed in upper rock cuts along Governors Drive/Highway 431 across Monte Sano heading into Big Cove
Hartselle Sandstone 0-90 910 Sandstone, tan to brownish gray, medium to coarse grained, hard, sharp edged grains Found all across the upper crest of Chapman Mountain, Weatherly Mountain, King Mountain, and Garth Mountain
Gasper Formation 40-90 820 Limestone, light-gray to gray, argillaceous, crystalline, abundantly fossiliferous, partly oolitic, some shale layers. Large exposure all across mountainous slopes
Meremac St. Genevieve Limestone 180+/- 640 Limestone, light gray, oolitic, thick-bedded, fossiliferous Exposure along lower base of mountains
Tuscumbian Limestone 150-200 below median ground level Limestone, dark to light gray, crystalline, massive bedded, fossiliferous, some chert near base of layer Outcroppigs all across Huntsville including Big Springs Park below banks and the courthouse. Thick layers below surface all across metro area. Red Clay Forming.
Osage Fort Payne Chert 95-160 below median ground level Limestone, gray and yellow, abundant chert, highly porous Heavily Saturated Ground water bearing formation. Tapped into at Dallas Wells.
Devonian Chattanooga Shale 0.5-10 below median ground level Shale, black, hard, fissile, contains bitumen and pyrite, some sand, partly radioactive Thin seams found along Flint River Basin in Northeast and North Central Madison County near Riverton Area.
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