USGS Visual Identifier
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Geologic Unit: Collinsville

Collinsville Formation (CT*,MA*)

Ordovician, Middle*

Geologic Province:
New England province*

Areal Extent:

Type Locality:
Between highest and lowest water level of Nepaug Reservoir, on southern face of Sweetheart Mountain, near village of Collinsville, Canton Twp., Hartford Co., CT (Gregory, 1906).

Bristol (CT*,MA*) and Sweetheart Mountain (CT*,MA*). Members; unnamed hornblende gneiss member (CT), unnamed metaquartzite member (CT)

Unit Name History:
Named Collinsville granite-gneiss (Rice and Gregory, 1906).
Redescribed as Collinsville Formation (Stanley, 1964).
Revised, Extended into MA (Stanley, 1980).
MA State Geol. Map usage (Zen and others, 1983).
Areal limits; Overview (Stanley and Hatch, 1988).
Revised (Simpson, 1990).

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