USGS Visual Identifier
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Geologic Unit: Partridge

Partridge Formation (NH*,CT*,MA*,ME*,VT*)

Ordovician, Middle*
Ordovician, Late*

Geologic Province:
New England province*

Areal Extent:

Type Locality:
Partridge Lake, Littleton Twp., Grafton Co., NH (Billings, 1934).

Unit Name History:
Named Partridge slate in NH (Billings, 1934) [From GNC index card files; not synopsized].
Renamed Partridge formation (Billings, 1935) [From GNC index card files; not synopsized].
Overview (Cameron and others, 1954) [From GNC index card files; not synopsized].
MA State Geol. Map usage; Extended into MA, VT, CT (Zen and others, 1983).
Revised (Robinson and Luttrell, 1985).
Areally restricted in MA (Hatch and others, 1988).
Revised; Areal limits (Moench, 1990).
Age modified; Isotopic dating (Tucker and Robinson, 1990).
Revised; Extended into ME; Age modified; Biostratigraphic dating (Moench and others, 1995).
NH State Geol. Map usage; Age modified (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