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National Geologic Map Database
Map showing publication footprint
  • Usage in publication:
    • Frenchtown diorite
  • Modifications:
    • Named
  • Dominant lithology:
    • Diorite
  • AAPG geologic province:
    • Piedmont-Blue Ridge province
Publication:

Grimsley, G.P., 1894, The granites of Cecil County, in northeastern Maryland: Cincinnati Society of Natural History Journal, v. 17, p. 59-67, 78-114.


Summary:

Name Frenchtown diorite used to refer to gabbro diorite near Frenchtown, Cecil Co., MD. Age unknown.

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


Map showing publication footprint
  • Usage in publication:
    • Frenchtown Member*
  • Modifications:
    • Revised
  • AAPG geologic province:
    • Piedmont-Blue Ridge province
Publication:

Higgins, M.W., 1977, Six new members of the James Run Formation, Cecil County, northeastern Maryland, IN Sohl, N.F., and Wright, W.B., Changes in stratigraphic nomenclature by the U.S. Geological Survey, 1976: U.S. Geological Survey Bulletin, 1435-A, p. A122-A127.


Summary:

Frenchtown diorite of Grimsley (1894) adopted as Frenchtown Member of James Run Formation (of Glenarm Group) as redefined in this report. Unit includes green, dark- to medium-gray, and light gray interbedded and multiply folded metavolcanic, metavolcaniclastic, and metavolcanic epiclastic rocks. Thickness approximately 915 m. Overlies Principio Furnace Member (new) of James Run; probably partly equivalent to Little Northeast Creek Member (new) of James Run. Underlies Gilpins Falls Member of James Run. Age is early Paleozoic.

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 ([ ]).

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