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National Geologic Map Database

Geologic Unit: Baltimore

Usage:

Baltimore Gneiss (DE*,MD*,NJ*,PA*,VA*)


Geologic age:

Middle Proterozoic*


Type section, locality, area and/or origin of name:

Type locality: exposures along banks of Jones Falls and Gwynns Falls, city of Baltimore, MD. Named from city of Baltimore (Knopf and Jonas, 1929).
Principal reference section: outcrops along Towson Run and Bellona Ave. to Towsontown Blvd., Towson and Cockeysville quadrangles (Crowley, 1976).
Reference section: outcrop at approx. 200 ft elevation, south side of DE Route 82, west of town of Yorklyn, and south of the Red Clay Creek flood plain (locality Bb25-b), Lat. 39 deg. 48 min. 23 sec. N., Long. 75 deg. 40 min. 47 sec. W., Kennett Square 7.5-min quadrangle, New Castle Co., DE (Plank and others, 2000).


AAPG geologic province:

Piedmont-Blue Ridge province*


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