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National Geologic Map Database
Map showing publication footprint
  • Usage in publication:
    • Brookfield diorite
  • Modifications:
    • Original reference
  • Dominant lithology:
    • Diorite
  • AAPG geologic province:
    • New England province
Publication:

Gregory, H.E., 1906, The crystalline rocks, Chapter II, IN Rice, W.N., and Gregory, H.E., Manual of the geology of Connecticut: Connecticut Geological and Natural History Survey Bulletin, no. 6, p. 39-155.


Summary:

Pg. 107 and map. Brookfield diorite. Extends from near New Milford southward to Bookfield Center, with length of about 8 miles and width of 1 mile. Is usually massive, but shows also gneissoid and even schistose phases. Both light and dark types are present in formation. Intrudes Poughquag quartzite [Lower Cambrian] and the schists of the region [Berkshire and Hoosac, of Ordovician age].

Source: US geologic names lexicon (USGS Bull. 896, p. 273).


Map showing publication footprint
  • Usage in publication:
    • Brookfield diorite
  • Modifications:
    • Overview
  • AAPG geologic province:
    • New England province
Publication:

Agar, W.M., 1934, The granites and related intrusives of western Connecticut: American Journal of Science, 5th series, v. 27, no. 161, p. 354-373.


Summary:

Brookfield diorite is older than Thomaston granite and appears to be younger than Bristol quartz diorite, Hartland schist, and Becket granite gneiss.

Source: US geologic names lexicon (USGS Bull. 896, p. 273).


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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