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National Geologic Map Database
Map showing publication footprint
  • Usage in publication:
    • Walloomsac Formation*
  • Modifications:
    • Age modified
    • Biostratigraphic dating
  • AAPG geologic province:
    • New England province
Publication:

Ratcliffe, N.M., 1974, Bedrock geologic map of the State Line quadrangle, Columbia County, New York, and Berkshire County, Massachusetts: U.S. Geological Survey Geologic Quadrangle Map, GQ-1142, scale 1:24,000 [http://ngmdb.usgs.gov/Prodesc/proddesc_10682.htm]


Summary:

Basal limestone of Walloomsac contains pelmatozoans, bryozoans, algae remains, and conodonts. Conodonts exposed at No Bottom Pond indicate a Middle Ordovician or slightly younger age (according to J. Huddleston, USGS). Age of whole unit is Middle and Late(?) Ordovician.

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


Map showing publication footprint
  • Usage in publication:
    • Walloomsac Formation*
  • Modifications:
    • Geochronologic dating
  • AAPG geologic province:
    • New England province
Publication:

Marvin, R.F., and Dobson, S.W., 1979, U.S. Geological Survey radiometric ages; Compilation "B": Isochron/West, no. 26, p. 3-32.


Summary:

Pg. 15, geologic time scale (inside front cover). Walloomsac Formation (Middle Ordovician). Sample from staurolite-garnet schist, at Lat. 41 deg. 59 min. 45 sec. N., Long. 73 deg. 25 min. 00 sec. W., Sharon quadrangle, Litchfield County, Connecticut, yielded a Rb-Sr age of 368 +/-19 Ma (biotite). Age recalculated, using decay constants of Steiger and Jager, 1977 (Earth Planet. Sci. Letters, v. 36, p. 359-362), from Zen and Hartshorn's (1966) published age of 355 Ma for this sample. Zartman and others (1970) reported a K-Ar age of 390 Ma (muscovite). Initial age of schist (Middle Ordovician) disturbed by later metamorphism [Devonian].

Source: Publication.


Map showing publication footprint
  • Usage in publication:
    • Walloomsac Formation*
  • Modifications:
    • Overview
  • AAPG geologic province:
    • New England province
Publication:

Zen, E-an (editor), Goldsmith, Richard (compiler), Ratcliffe, N.M. (compiler), Robinson, Peter (compiler), Stanley, R.S. (compiler), Hatch, N.L., Jr., Shride, A.F., Weed, E.G.A., and Wones, D.R., 1983, Bedrock geologic map of Massachusetts: U.S. Geological Survey [State Geologic Map], scale 1:125,000


Summary:

Used as Walloomsac Formation of Middle Ordovician age. Mapped as one main unit and three informal, unnamed subunits. Subunit consisting of tan to dark-blue laminated quartzite and calcareous quartzite was previously mapped by other workers as Bellowspipe Quartzite [name not used on this map].

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


Map showing publication footprint
  • Usage in publication:
    • Walloomsac Formation*
  • Modifications:
    • Revised
    • Areal extent
Publication:

Baskerville, C.A., 1992, Bedrock and engineering geologic maps of Bronx County and parts of New York and Queens Counties, New York: U.S. Geological Survey Miscellaneous Investigations Series Map, I-2003, scale 1:24,000


Summary:

In this map area, Manhattan Schist member A is replaced by Walloomsac Formation based on work by Jackson and Hall (1982), Hall (in press), and A.A. Drake (1990., pers. commun.).

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


Map showing publication footprint
  • Usage in publication:
    • Walloomsac Formation*
  • Modifications:
    • Age modified
    • Biostratigraphic dating
  • AAPG geologic province:
    • New England province
Publication:

Ratcliffe, N.M., Potter, D.B., and Stanley, R.S., 1993, Bedrock geologic map of the Williamstown and North Adams quadrangles, Massachusetts and Vermont, and part of the Cheshire quadrangle, Massachusetts: U.S. Geological Survey Miscellaneous Investigations Series Map, I-2369, 2 sheets, 13 p., scale 1:24,000


Summary:

Thin limestone unit near base of Walloomsac locally contains abundant bryozoan fragments, cup corals, pelmatozoan hash, and conodonts that indicate that the base of the Walloomsac is Rocklandian (middle and late Caradocian) or younger. Age of unit is Middle Ordovician.

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


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