Pg. 33, 34, 41. Prescott Intrusive Complex. Central, early-formed gabbro surrounded by strongly foliated and lineated biotite quartz diorite, granodiorite, and quartz monzonite. Cuts across axial surface of an early recumbent syncline, but strong tectonic fabric indicates emplacement prior to or during major deformation associated with formation of gneissic domes. Includes Cooleyville Granitic Gneiss (new). Older than Belchertown Intrusive Complex (new). Age is Devonian(?).
In Bronson Hill anticline, [west-central Massachusetts], a complex zone ef gneiss domes and recumbent folds. Lies near center of Appalachian tectonic belt of New England. Anticline underwent intense deformation and metamorphism in middle or late Paleozoic time.

Source: US geologic names lexicon (USGS Bull. 1350, p. 599).

Used as Prescott Complex. Includes Cooleyville Granitic Gneiss. Age is Devonian. [No explanation given for name and age changes.]

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

Prescott Diorite (Emerson, 1898, 1917) was renamed Prescott Intrusive Complex by Mackower (1964, unpub. Ph.D dissertation; see also Robinson, 1967) to include both the original diorite (redescribed as hornblende gabbro) and surrounding gneissic biotite tonalite, granodiorite, and Cooleyville Granitic Gneiss. Prescott Intrusive Complex is here revised to Prescott Complex. All exposures of Prescott Complex are on present Prescott Peninsula of Quabbin Reservoir. Hornblende gabbro is prominently exposed on Packard Mountain and two unnamed mountains to the south. Gabbro intrudes and contains inclusions of Partridge Formation; gabbro is intruded by and appears as inclusions in Cooleyville Granitic Gneiss. Age is changed from Late Carboniferous or post-Carboniferous (Emerson, 1917) to Devonian on basis of radiometrically dated Cooleyville.
Name is taken from Prescott, MA, a town that was obliterated by establishment of Quabbin Reservoir.

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