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National Geologic Map Database
Geologic Unit: Merrimack
Map showing publication footprint
  • Usage in publication:
    • Merrimack Group*
  • Modifications:
    • Age modified
    • Overview
  • AAPG geologic province:
    • New England province
Publication:

Goldsmith, Richard, Grew, E.S., Hepburn, J.C., and Robinson, G.R., 1982, Formation names in the Worcester area, Massachusetts, IN Stratigraphic notes, 1980-1982: U.S. Geological Survey Bulletin, 1529-H, p. H43-H56.


Summary:

Formations of Merrimack Group recognized as valid units in northeastern MA. Kittery Quartzite is revised to Kittery Formation following usage of Novotny (1963) and Hussey (1968). Age of Kittery is Silurian or Ordovician because it is intruded by granodiorite of Newburyport Complex (name revised) dated as Silurian and Ordovician (R.E. Zartman and R.S. Naylor, written commun., 1981). Eliot and Berwick Formations remain as probable Silurian age on basis of tentative correlation with similar rocks in central ME (Osberg, 1968). Stratigraphic order within Merrimack Group is uncertain, but it appears that Kittery is basal unit. [GNC records indicate that the names Merrimack Formation or Merrimack Quartzite are no longer valid anywhere.]

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


Map showing publication footprint
  • Usage in publication:
    • Merrimack Group
  • Modifications:
    • Not used
  • 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], 3 sheets, scale 1:250,000


Summary:

Kittery, Eliot, and Berwick Formations are shown, but they are not assigned to Merrimack Group. [No explanation as to why. Merrimack still good usage.]

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


Map showing publication footprint
  • Usage in publication:
    • Merrimack Group*
  • Modifications:
    • Overview
    • Age modified
    • Geochronologic dating
  • AAPG geologic province:
    • New England province
Publication:

Lyons, J.B., Bothner, W.A., Moench, R.H., and Thompson, J.B., Jr., 1997, Bedrock geologic map of New Hampshire: U.S. Geological Survey [State Geologic Map], 2 sheets, scale 1:250,000 and 1:500,000, Prepared in cooperation with DOE and State of New Hampshire


Summary:

Used as Merrimack Group, consisting of Berwick, Eliot, and Kittery Formations. Ordovician(?) to Silurian(?) age is based on isotopic age determinations of approx 440 and 420 Ma from detrital zircons from the Berwick by J.N. Aleinikoff (oral commun., 1994). Report includes geologic map, cross sections, correlation chart, and four 1:500,000-scale derivative maps.

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 ([ ]).