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Map showing publication footprint
  • Usage in publication:
    • Octoraro schist*
  • Modifications:
    • Named
  • Dominant lithology:
    • Schist
  • AAPG geologic province:
    • Piedmont-Blue Ridge province
Publication:

Bascom, Florence, Clark, W.B., Darton, N.H., Knapp, G.N., Kummel, H.B., Miller, B.L., and Salisbury, R.D., 1909, Philadelphia folio, Norristown, Germantown, Chester, and Philadelphia, Pennsylvania-New Jersey-Delaware: U.S. Geological Survey Geologic Atlas of the United States Folio, GF-162, 23 p.


Summary:

Name Octoraro schist introduced to replace Wissahickon mica schist, which according to authors is younger than Wissahickon mica gneiss. The schist overlies Shenandoah limestone, and is of Ordovician age, while Wissahickon mica gneiss is assigned to Precambrian.

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


Map showing publication footprint
  • Usage in publication:
    • Octoraro schist†
  • Modifications:
    • Abandoned
  • AAPG geologic province:
    • Piedmont-Blue Ridge province
Publication:

Knopf, E.B., and Jonas, A.I., 1929, Geology of the McCalls Ferry-Quarryville district, Pennsylvania: U.S. Geological Survey Bulletin, 799, 156 p.


Summary:

It is shown in this report that the "Octoraro schist" is not a stratigraphic unit and that the formations that made up the old "Octoraro" are part of a conformable sequence of Precambrian rocks of the Glenarm series.

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


Map showing publication footprint
  • Usage in publication:
    • Octoraro Phyllite*
  • Modifications:
    • Reinstated
    • Revised
  • AAPG geologic province:
    • Piedmont-Blue Ridge province
Publication:

Lyttle, P.T., and Epstein, J.B., 1987, Bedrock geologic map of the Newark 2 degrees quadrangle, New York, New Jersey, and Pennsylvania: U.S. Geological Survey Miscellaneous Investigations Series Map, I-1715, 2 sheets, scale 1:250,000 [http://ngmdb.usgs.gov/Prodesc/proddesc_9892.htm]


Summary:

Name Octoraro schist of Bascom (1909) is here reinstated as Octoraro Phyllite. Age of Late Proterozoic to Cambrian is based on regional correlations with similar rocks in the high taconic slices of the Berkshires of MA, such as the Everett Formation.

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


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

Valentino, D.W., Gates, A.E., and Glover, Lynn, III, 1994, Late Paleozoic transcurrent tectonic assembly of the central Appalachian Piedmont: Tectonics, v. 13, no. 1, p. 110-126.


Summary:

Octoraro Formation as shown in figure 4 is divided into three informal members. Basal Puseyville member consists of interlayered plagioclase-schist and quartz metasandstone. Overlying Stewarts Run member is a plagioclase schist and Bowery Run member, at the top, is a quartz-mica schist. Members are not discussed in the text.

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


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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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