USGS Visual Identifier
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Geologic Unit: Hoosac

Hoosac Formation (MA*,CT*,VT*)
Hoosac Schist (MA*,CT*)

Proterozoic, Late*
Cambrian, Early*
Geologic Province:
New England province*

Areal Extent:

Type Locality:
Exposures on Hoosac Mountain, Berkshire Co., northern MA (Emerson, 1892, unpub. report).

Bull Hill Member (VT), Turkey Mountain Member (VT*), Plymouth Member (VT).

Unit Name History:
Named (Emerson, 1892, unpub. report) [Not synopsized].
Extended into VT (Pumpelly and others, 1894).
Extended into CT (Gregory, 1909).
Age modified (Prindle and Knopf, 1932).
Revised, members named; Age modified (Thompson, 1952).
Age modified (Herz, 1961; Zen, 1967; Cady, 1969; Hatch, 1969; Ratcliffe, 1979).
MA State Geol. Map usage (Zen and others, 1983).
CT State Geol. Map usage (Rodgers, 1985).
Areal limits (Thompson, 1990).
Age modified (Ratcliffe and others, 1993).
Revised (Ratcliffe, 1993).
Overview (Ratcliffe, 1994).
Revised (Ratcliffe, in press).

Note: If you need more information, please contact Nancy Stamm (
Asterisks (*) indicate usage by the U.S. Geological Survey. Other usages by state geological surveys.

"No current usage" implies that a name has been abandoned or that it has fallen into disuse. Former usage and, if known, replacement name given in parentheses ().

Slashes (/) indicate unit name usage violates the 1983 North American Stratigraphic Code. This violation may be explained within brackets ([ ]).

U.S. Department of the Interior, U.S. Geological Survey, Reston, VA, USA
Database project personnel
Last modified: 15-Jan-2013