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Mineral Resources > Online Spatial Data > Geology > by state > Alabama Geology

Geologic units in Randolph county, Alabama

[Additional scientific data in this geographic area]

Wedowee Group; Hackneyville Schist (Precambrian to Paleozoic) at surface, covers 3 % of this area

Hackneyville Schist - medium to coarse-grained quartz-plagioclase +/- almandine +/- kyanite +/- biotite-muscovite schist, graphite-muscovite-quartz schist, and quartzite containing biotite. Large porphyroblasts of muscovite, andalusite and/or chiastrolite common. Rocks in the areas between Goodwater in Coosa County and Millerville in Clay County that are here assigned to the Hackneyville Schist also have been interpreted as part of the Higgins Ferry Group.

Lithology: schist; quartzite

Ketchepedrakee Amphibolite (Precambrian to Paleozoic) at surface, covers 0.3 % of this area

Ketchepedrakee Amphibolite - dark-green to black fine to coarse-grained, layered to massive amphibolite mixed with zones of chlorite actinolite schist, includes all amphibolite associated with the Poe Bridge Mountain Group.

Lithology: amphibolite; schist

Emuckfaw Group; Glenloch Schist (Precambrian to Paleozoic) at surface, covers 2 % of this area

Glenloch Schist - graphite-garnet-muscovite schist with interlayered metagraywacke.

Lithology: mica schist; metasedimentary rock

Almond Trondhjemite (Precambrian to Paleozoic) at surface, covers 2 % of this area

Almond Trondhjemite - leucocratic, fine to medium-grained, locally foliated trondhjemite containing abundant muscovite and locally biotite and epidote.

Lithology: trondhjemite

Wedowee Group; Cornhouse Schist (Precambrian to Paleozoic) at surface, covers 6 % of this area

Cornhouse Schist - medium to coarse-grained multiply foliated +/- plagioclase +/- garnet-biotite-muscovite-quartz schist interlayed with chlorite-biotite-garnet schist, typically mylonitic.

Lithology: schist

Dadeville Complex; Rock Mills Granite Gneiss (Precambrian to Paleozoic) at surface, covers 8 % of this area

Rock Mills Granite Gneiss - coarse to medium-grained biotite granite gneiss; locally includes thick bands of epidote and thin, small amphibolite bodies. Boundary between Rock Mills Granite Gneiss and Camp Hill Granite Gneiss arbitrarily defined.

Lithology: granitic gneiss; amphibolite

Jacksons Gap Group; Jacksons Gap Group undifferentiated in part (Precambrian to Paleozoic) at surface, covers 3 % of this area

Jacksons Gap Group undivided - principally graphitic sericite (muscovite)-quartz schist; includes sericite-quartz phyllonite; sericite phyllonite, blastomylonite, porphyroclastic blastomylonite schist, and mylonite quartzite occur principally along margins in south and form most of unit northeast of Jacksons Gap, Tallapoosa County.

Lithology: schist; phyllonite; mylonite; quartzite

Wedowee Group; Wedowee Group undifferentiated (Precambrian to Paleozoic) at surface, covers 45 % of this area

Wedowee Group undifferentiated - Wedowee Group undifferentiated includes the Cragford Phyllite and Cutnose Gneiss. Cragford Phyllite -- interbedded fine-grained graphite-chlorite-sericite schist and phyllite, garnet-sericite schist and phyllite, graphite-quartz-sericite phyllite, locally feldspathic biotite gneiss, calc-silicate rock, and quartzite. Cutnose Gneiss -- cyclically interbedded fine-grained quartz-biotite feldspathic gneiss, graphite-chlorite-sericite schist, locally thin interbeds of graphite-quartz-sericite phyllite, and quartzite. Rocks in the area northeast of Clanton in Chilton and Coosa Counties that are here assigned to the Wedowee Group also have been interpreted as part of the Higgins Ferry Group.

Lithology: schist; phyllite; felsic gneiss; quartzite; calc-silicate rock

Beaverdam Amphibolite (Precambrian to Paleozoic) at surface, covers 2 % of this area

Beaverdam Amphibolite - dark-green to dark-gray hornblende amphibolite, extensively sheared and folded, and locally retrograded to actinolite-tremolite-chlorite schist. Includes all amphibolite associated with the Wedowee Group.

Lithology: amphibolite; schist

Poe Bridge Mountain Group; Roscoelite-graphite quartz schist and graphitic quartzite (Precambrian to Paleozoic) at surface, covers < 0.1 % of this area

Poe Bridge Mountain Group; Roscoelite-graphite quartz schist and graphitic quartzite. Rocks in the area of Turkey Heaven Mountain in Cleburne and Randolph Counties that are here assigned to the Poe Bridge Mountain Group also have been interpreted as part of the Wedowee Group.

Lithology: schist; quartzite

Mad Indian Group (Precambrian to Paleozoic) at surface, covers 15 % of this area

Mad Indian Group - fine-grained feldspathic biotite gneiss; medium to coarse-grained muscovite-biotite-garnet schist; locally kyanite and sillimanite. Many of the schists have been retrograded to chlorite-garnet-quartz-sericite schist. Both mi and migr extensively cut by feldspathic dikes and pegmatites.

Lithology: felsic gneiss; schist; pegmatite

Bluff Springs Granite (Precambrian to Paleozoic) at surface, covers 0.6 % of this area

Bluff Springs Granite - leucocratic quartz diorite (tonalite) to quartz monzonite or trondhjemite, locally foliated.

Lithology: tonalite; quartz monzonite; trondhjemite

Mylonitic and Cataclastic Rocks in the Brevard, Towaliga, and Goat Rock Fault Zones (Precambrian to Paleozoic) at surface, covers 0.6 % of this area

Mylonitic and Cataclastic Rocks in the Brevard, Towaliga, and Goat Rock Fault Zones - mylonite and blastomylonite; contains minor ultramylonite, mylonite schist, and mylonite gneiss.

Lithology: mylonite; schist; gneiss

Mad Indian Group; Irregular zones of sericite-quartz schist (Precambrian to Paleozoic) at surface, covers 1.0 % of this area

Mad Indian Group; Irregular zones of sericite-quartz schist - irregular zones of sericite-quartz schist (+/- garnet) containing finely disseminated graphite, possibly infolded Wedowee Group equivalents. Both mi and migr extensively cut by feldspathic dikes and pegmatites.

Lithology: schist; pegmatite

Emuckfaw Group; Emuckfaw Group undifferentiated in part (Precambrian to Paleozoic) at surface, covers 7 % of this area

Emuckfaw Group undifferentiated in part - interbedded muscovite +/- garnet-biotite schist, metagraywacke, calc-silicate rock, and quartzite; rare thin amphibolite. Includes thin layers of aluminous graphitic schist. Locally sheared to mylonite schist.

Lithology: mica schist; metasedimentary rock; quartzite; calc-silicate rock; amphibolite

Poe Bridge Mountain Group (Precambrian to Paleozoic) at surface, covers 0.6 % of this area

Poe Bridge Mountain Group - coarse to fine-grained feldspathic graphite schist, +/- staurolite +/- kyanite +/- sillimanite-muscovite-biotite schist, and garnet-biotite-muscovite schist, and gneiss; locally common pegmatites. Rocks in the area of Turkey Heaven Mountain in Cleburne and Randolph Counties that are here assigned to the Poe Bridge Mountain Group also have been interpreted as part of the Wedowee Group.

Lithology: mica schist; gneiss; pegmatite

Dadeville Complex; Waresville Schist (Precambrian to Paleozoic) at surface, covers 2 % of this area

Waresville Schist - banded amphibolite interlayered with chlorite schist, chlorite amphibolite, chlorite-actinolite schist, chlorite +/- magnetite quartzite, and actinolite quartzite; may include small ultramafic pods.

Lithology: amphibolite; schist; quartzite; ultramfic intrusive rock