U.S. Geological Survey Home AASG Logo USGS HOME CONTACT USGS SEARCH USGS
National Geologic Map Database
Geologic Unit: Mahan
Search archives
Map showing publication footprint
  • Usage in publication:
    • Mahan formation
  • Modifications:
    • Named
  • Dominant lithology:
    • Limestone
    • Chert
  • AAPG geologic province:
    • Appalachian basin
Publication:

Cooper, G.A., 1956, Chazyan and related brachiopods [U.S.-Canada]: Smithsonian Miscellaneous Collections, v. 127, pt. 1, 1245 p.


Summary:

Named the Mahan formation for Mahan Road, Snow Hill quad., Hamilton Co., southeastern TN. Consists of ribbon-banded to thick-bedded, dove-gray calcilutite, lower half of which is characteristically studded with plates and nodules of black chert. Upper part is even-bedded calcilutite with numerous shaly interbeds. Thickness is 200 feet. Overlies Long Savannah formation. Top of unit is defined at type locality by a red mudstone, one of several intercalations in a thick succession of ribbon-banded limestones. The Mahan is of Middle Ordovician (Mohawkian) age.

Source: GNU records (USGS DDS-6; Reston GNULEX).


For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.

Asterisk (*) indicates usage by the U.S. Geological Survey. Other usages by state geological surveys.

"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 does not conform with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005). This may be explained within brackets ([ ]).