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ALABAMA Mt. Cheaha 7 ½ quad: Cheaha Mountain, AL Cleburne County Cheaha State Park Talladega Mountains, east margin of Blue Ridge Province
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Metamorphic (metamorphosed sedimentary) 2,407 ft (734 m) |
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| Quartz pebble conglomerate. | ||||||||||||||||
| Bedrock: Cheaha Quartzite Member of Lay Dam Formation | ? Silurian | |||||||||||||||
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Light gray to white, coarse- to medium-grained metasandstone and conglomerate. Outcrops are well exposed all around the summit, especially at look-out points such as Bald Rock and Pulpit Rock. The coarse sand grains are often smoky quartz; a few are feldspar. Silurian conodont fossils have been described from some parts of the formation, but not in the park. Cross beds and graded beds are upright and layers dip southeast on the mountain. Phyllites in other members of the Lay Dam Formation are at lower greenschist facies metamorphism, probably dating from the Devonian. The Talladega Mountains and the Cheaha Quartzite both end abruptly to the southwest, apparently truncated by a thrust fault.
The Lay Day Formation is part of the Talladega Group, which is sandwiched between the Cambrian-Ordovician carbonate shelf sequence (in the Rome thrust sheet) to the west, and the Hillabee greenstone, also in thrust sheets, to the southeast. The Lay Dam Formation apparently received sediments both from the carbonate shelf and from the metamorphosed Bill Arp thrust sheet advancing from the southeast. Thus it could be described as a syn-orogenic flysch deposit. The Hillabee is host to the Dempsey gold-pyrite deposit southeast of Mount Cheaha. Soil Series: Cheaha stony soil, moderately deep, well drained, formed from micaceous metasandstone under forest soils.
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