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Geologic Unit: Hartley
Map showing publication footprint
  • Usage in publication:
    • Hartley augen gneiss*
  • Modifications:
    • Named
  • Dominant lithology:
    • Gneiss
  • AAPG geologic province:
    • Piedmont-Blue Ridge province
Publication:

Knopf, E.B., and Jonas, A.I., 1923, Stratigraphy of the crystalline schists of Pennsylvania and Maryland: American Journal of Science, 5th series, v. 5, no. 33, p. 40-62.


Summary:

The Baltimore gneiss has been intruded by a granite that has produced a lit-par-lit injection in upper part of formation. This granite, which has been metamorphosed into a cataclastic granite gneiss, is here called the Hartley augen gneiss, from its excellent outcrops at Hartley Mill, Baltimore Co., MD.

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


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

Crowley, W.P., Higgins, M.W., Bastian, T., and Olsen, S., 1970, New interpretations of eastern Piedmont geology of Maryland, IN Guidebook for the 35th annual field conference of Pennsylvania geologists: Field Conference of Pennsylvania Geologists, no. 35, p. 1-60.


Summary:

Hartley Augen Gneiss of Knopf and Jonas (1923, 1929) reduced in rank to Hartley Member and assigned to Baltimore Gneiss in MD.

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


Map showing publication footprint
  • Usage in publication:
    • Hartley
  • Modifications:
    • Not used
  • 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:

The Baltimore Gneiss is subdivided into four unnamed members. The Hartley Augen Gneiss of Knopf and Jonas (1925, 1929) is designated the augen gneiss member in this report.

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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