The National Geologic Map Database is migrating to a new infrastructure. We apologize for any service disruptions during this process.

U.S. Geological Survey Home AASG Logo USGS HOME CONTACT USGS SEARCH USGS
National Geologic Map Database
Map showing publication footprint
  • Usage in publication:
    • Mixer Pond Member
  • Modifications:
    • Named
  • Dominant lithology:
    • Gneiss
  • AAPG geologic province:
    • New England province
Publication:

Bickel, C.E., 1976, Stratigraphy of the Belfast quadrangle, Maine, IN Page, L.R., ed., Contributions to the stratigraphy of New England: Geological Society of America Memoir, 148, p. 108-110.


Summary:

Passagassawakeag Formation is here proposed to replace term Knox Gneiss of Perkins and Smith (1925). Unit is subdivided into a basal calc-silicate member (30-150 m) and the upper Mixer Pond Member (new name) (300 m). Mixer Pond described as light-gray to white, fine-grained, massive, and compositionally layered feldspathic gneiss composed of hornblende, biotite, ferrosalite, and magnetite. Isotopic dating of Passagassawakeag by Zartman (oral commun., 1974) and Brookins (1975, written commun.) ranges from 430+/-10 m.y. (Pb206-Pb207, zircons) to 600+/-80 m.y. (Rb-Sr).

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


Map showing publication footprint
  • Usage in publication:
    • Mixer Pond Member*
  • Modifications:
    • Age modified
  • AAPG geologic province:
    • New England province
Publication:

Wones, D.R., 1991, Bedrock geologic map of the Orland quadrangle, Hancock and Penobscot Counties, Maine: U.S. Geological Survey Geologic Quadrangle Map, GQ-1691, 1 sheet, scale 1:62,500


Summary:

Age of the Passagassawakeag Gneiss and its Mixer Pond Member of Bickel (1976) is Proterozoic(?) to 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 ([ ]).

Accessibility FOIA Privacy Policies and Notices

USA Gov U.S. Department of the Interior | U.S. Geological Survey
Supported by the National Cooperative Geologic Mapping Program
Page Contact Information: Personnel
Page Last Modified: Thu 21 May 2026 05:10:41 PM MDT