- Usage in publication:
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- Dean formation
- Modifications:
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- Named
- Dominant lithology:
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- Schist
- Conglomerate
- Quartzite
- AAPG geologic province:
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- Piedmont-Blue Ridge province
Summary:
Named as youngest member of Great Smoky group in this area. Named for Dean Ridge in Mineral Bluff quad, Fannin Co., northernmost GA. Crops out in 0.5-mi-wide belt on each limb of Murphy syncline. Western belt extends along Dean Ridge, through Windy Ridge, and along upper course of Sugar Creek. Eastern belt lies just west of Lake Toccoa. Best exposures are along Dean Ridge, north of Mineral Bluff, and along GA Hwy 5, northwest of Blue Ridge. Consists of staurolite-mica schist, X-biotite schist, metaquartz conglomerate, quartzite, and pseudodiorite; these are interbedded with lesser amounts of gray slate or phyllite and sericite schist. Except for abundance of X-biotite schist and absence of quartz-kyanite schist at its top, Dean is lithologically indistinguishable form Hughes Gap formation lower in Great Smoky group. Thickness is 2300 to 3500 ft. Underlain by Hothouse formation; upper contact marked by dark slate of Nantahala slate. Report includes geologic map, correlation chart, and extensive mineral analyses of Dean formation. Age is Precambrian.
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
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- Dean Formation
- Modifications:
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- Overview
- AAPG geologic province:
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- Appalachian basin
Summary:
In Ducktown area, Dean Formation is included with Copperhill, Hughes Gap, and Hothouse Formations in Great Smoky Group, undivided, of Precambrian age.
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
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- Dean Formation
- Modifications:
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- Areal extent
- AAPG geologic province:
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- Piedmont-Blue Ridge province
Summary:
Correlation chart (fig. 2) shows the following relations. The Great Smoky Group in western NC consists of five formations (ascending): Thunderhead, Anakeesta, Grassy Branch (new name), Ammons (new name), and Dean Formations (chart implies that Dean and top of Ammons are time equivalent). Grassy Branch Formation is applied to unnamed beds mapped by King and others (1958) above Anakeesta Formation. In relation to Great Smoky Group mapped by Hurst (1955) in Mineral Bluff quad, GA, Anakeesta correlates with Copperhill Formation, Grassy Branch correlates with Hughes Gap Formation, and Ammons correlates with Hothouse and Dean Formations.
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
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- Dean Formation
- Modifications:
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- Areal extent
- AAPG geologic province:
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- Piedmont-Blue Ridge province
Summary:
Dean Formation of Great Smoky Group of Ocoee Supergroup is mapped in Blue Ridge belt of western NC. Age is Late Proterozoic.
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
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- Dean Formation*
- Modifications:
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- Areal extent
- AAPG geologic province:
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- Piedmont-Blue Ridge province
Summary:
The Dean Formation of Hurst (1955) of the Great Smoky Group is assigned to the Bill Arp thrust sheet in the Murphy synclinorium in northern GA. Age is Late Proterozoic.
Source: GNU records (USGS DDS-6; Reston GNULEX).
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
Asterisk (*) indicates published by U.S. Geological Survey authors.
"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).
Slash (/) indicates name conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).