USGS Visual Identifier
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Geologic Unit: Hardwick

Hardwick Tonalite (MA*)
Hardwick Tonalite of New Hampshire Plutonic Suite (NH*)
Hardwick Quartz Diorite (MA*,NH*)

Devonian, Early*

Geologic Province:
New England province*

Areal Extent:

Type Locality:
Exposures at and around Hardwick, Worcester Co., central MA (Emerson, 1898).

Unit Name History:
[Please note: only the Zen and others (1983) and Lyons and others (1997) references include synopses here. The remaining references have yet to be added from the GNC index card files. Until then, feel free to contact us if you would like complete bibliographic citations.]
Named (Emerson, 1898).
Age modified (Collings and others, 1969).
Revised to Hardwick Quartz Diorite (Field, 1975).
Age modified; Overview of nomenclature (Ashwal and others, 1979).
MA State Geol. Map usage (Zen and others, 1983).
NH State Geol. Map usage (Lyons and others, 1997).

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