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National Geologic Map Database
Geologic Unit: McGraw
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Map showing publication footprint
  • Usage in publication:
    • McGraw limestone
  • Modifications:
    • Named
  • Dominant lithology:
    • Limestone
  • AAPG geologic province:
    • Appalachian basin
Publication:

Kay, Marshall, 1956, Ordovician limestones in the western anticlines of the Appalachians in West Virginia and Virginia northeast of the New River: Geological Society of America Bulletin, v. 67, no. 1, p. 55-106.


Summary:

Named the McGraw limestone for McGraw Gap, Alleghany Co., VA. Consists of well-bedded heavy-ledged brittle, rather pure calcitite. Generally occurs as 6 in. to 1 ft. ledges and irregularly laminated and having thin calcarenite lenses. Thickness is 9 feet at type section and reaches 40 feet with thinning occurring to southeast. Unit overlies the McGlone limestone with a sharp contact and unconformably underlies the Nealmont limestone. The McGraw is of Middle Ordovician age.

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


Map showing publication footprint
  • Usage in publication:
    • McGraw
  • Modifications:
    • Revised
  • AAPG geologic province:
    • Appalachian basin
Publication:

Bick, K.F., 1962, Geology of the Williamsville quadrangle, Virginia: Virginia Division of Mineral Resources Report of Investigations, no. 2, 40 p.


Summary:

The McGraw limestone is not used in western VA and rocks previously assigned to this interval are included in the McGlone limestone. The upper 12 feet of the McGlone is a fine-grained, gray limestone with yellow-brown argillaceous partings.

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 ([ ]).