Mount Mitchell (Black Dome)
7 ½’ quadrangle: Mt. Mitchell, NC
Mt. Mitchell State Park, Pisgah National Forest
Black Mountains, part of the Blue Ridge Province
Metamorphic (metamorphosed sedimentary)
6,684 ft (2,037 m)
Micaceous metagraywacke, schist and gneiss, described by Keith (1905) as Carolina Gneiss, a name regarded by Kesler (1944) as having "lithologic but not correlative value", because it had been applied too widely to various gneisses. The gneiss is dominantly quartz, feldspar and biotite mica, with some layers more biotite-rich than others. The rocks at the summit are metamorphosed graywacke, whose high quartz content is responsible for the rugged Black Mountains’ resistance to erosion.
The metagraywacke and interlayered sulfidic schist, graphitic schist, gneiss and metaconglomerate were originally deposited from 800 to 600 million years ago as sediments along the margin of Laurentia. They were thrust westward toward the craton, along with the rest of the Ashe Metamorphic Suite, during the Taconian Orogeny.
During the subsequent Acadian Orogeny, the gneisses experienced high-temperature metamorphism, the metagraywacke became foliated and quartz pebbles in the conglomerate were severely deformed. Local melting produced pegmatites, which contain muscovite dated by 40Ar/ 39Ar methods ranging from 385 to 325 Ma, core to rim, indicating protracted cooling from Devonian through Carboniferous time. The Museum of North Carolina Minerals, along the Blue Ridge Parkway about 28 miles north from Mt. Mitchell, is a great place to learn about the local geology.
Surficial Geology: Never glaciated. Soils derived from weathered bedrock. The Black Mountains were named that because of the dark color of conifers along the range; the Blue Ridge is called that because of the hazy blue color due to high humidity. Firs at Mt. Mitchell were destroyed by fire in 1912 and eventually recovered, but more recently the conifers have been threatened by acid rain. (See further discussion for Tennessee’s high point in the Great Smokies.)
Soil Series: Stony rough land and very steep, thin, dark brown Porters stony loam, formed on gneiss under chestnut and Fraser fir forests.
- Carpenter, P. Albert III, Editor, 1989, A Geologic Guide to North Carolina's State Parks : North Carolina Geological Survey Section, p.55-56.
- Hames, Willis E., M.G. Steltenpohl and R.J. Tracy, 2001, Applications of laser 40 Ar/ 39 Ar dating to studies of Appalachian metamorphic evolution, examples from New England and the southwestern Blue Ridge: Geological Society of America Abstracts with Programs v.33, no.2, p.6.
- Keith, Arthur, 1905, Mount Mitchell Folio, North Carolina-Tennessee: USGS Geologic Atlas of the United States, Folio 124.
- Kesler, Thomas L., 1944, Correlation of some metamorphic rocks in the central Carolina piedmont: Geological Society of America Bulletin v.55, no.6, p.755-782.
- Merschat, Carl E., 1997, Geology of Yancey County : North Carolina Geological Survey, Geologic Note No. 5, 22p.
- Perkins, S.O. and W. Getty, 1952, Soil Survey of Yancey County, North Carolina : US Department of Agriculture
Other suggested sources of information: