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  • Usage in publication:
    • Sweathouse Amphibolite Member
  • Modifications:
    • Named
  • Dominant lithology:
    • Amphibolite
  • AAPG geologic province:
    • Piedmont-Blue Ridge province
Publication:

Crowley, W.P., 1976, The geology of the crystalline rocks near Baltimore and its bearing on the evolution of the eastern Maryland Piedmont: Maryland Geological Survey Report of Investigations, no. 27, 40 p.


Summary:

Sweathouse Amphibolite Member of Oella Formation (Wissahickon Group) is here named for outcrops of schist and gneiss interlayered with epidote amphibolite along Sweathouse Branch of Gunpowder Falls in Baltimore Co., MD. The amphibolite is fine-grained, commonly with alternating felsic and mafic laminae. Member varies in thickness from 0 to at least 700 m. Hosts the Bare Hills Copper deposit. Overlies lower unnamed metasedimentary member and underlies Sykesville Formation of Wissahickon Group. Age of entire Wissahickon is shown as Cambrian-Ordovician(?).

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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