U.S. Geological Survey Home AASG Logo USGS HOME CONTACT USGS SEARCH USGS
National Geologic Map Database
Map showing publication footprint
  • Usage in publication:
    • Thorofare Mountain Formation
  • Modifications:
    • Named
  • Dominant lithology:
    • Sandstone
    • Conglomerate
    • Siltstone
    • Mudstone
  • AAPG geologic province:
    • Piedmont-Blue Ridge province
Publication:

Wehr, Frederick, 1985, Stratigraphy of the Lynchburg Group and Swift Run Formation, Late Proterozoic (730-570 Ma), central Virginia: Southeastern Geology, v. 25, no. 4, p. 225-239.


Summary:

The Thorofare Mountain Formation of the Lynchburg Group is here named in the Culpeper and Rockfish River areas in VA. In the Rockfish River area it has been called Loudoun Formation and Rockfish Conglomerate. It consists of medium-grained to pebbly, poorly-sorted feldspathic sandstone with minor conglomerate, siltstone, and graphitic mudstone. In the Culpeper area the Thorofare Mountain sharply overlies the Monumental Mills Formation; in the Rockfish River area it conformably overlies the Rockfish Conglomerate. Underlies the Ball Mountain Formation unconformably or in fault contact. Age is Late Proterozoic, based on 730 to 570 m.y. age of the Lynchburg Group.

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


Map showing publication footprint
  • Usage in publication:
    • Thorofare Mountain Formation*
  • Modifications:
    • Revised
  • AAPG geologic province:
    • Piedmont-Blue Ridge province
Publication:

Rankin, D.W. (editor), Chiarenzelli, J.R., Drake, A.A., Jr., Goldsmith, Richard, Hall, L.M., Hinze, W.J., Isachsen, Y.W., Lidiak, E.G., McLelland, James, Mosher, Sharon, Ratcliffe, N.M., Secor, D.T., Jr., and Whitney, P.R., 1993, Proterozoic rocks east and southeast of the Grenville Front, IN Reed, J.C., Jr., and others, eds., Precambrian; conterminous U.S.: Geological Society of America, The Geology of North America, The Decade of North American Geology (DNAG), v. C-2, p. 335-461.


Summary:

Thorofare Mountain Formation assigned to Fauquier Group (rank raised). Report includes geologic maps, correlation chart, and isotopic data.

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 ([ ]).

Accessibility FOIA Privacy Policies and Notices

USA Gov U.S. Department of the Interior | U.S. Geological Survey
Supported by the National Cooperative Geologic Mapping Program
Page Contact Information: Personnel
Page Last Modified: Thu 04 Apr 2024 03:33:57 PM MDT