USGS Visual Identifier
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Geologic Unit: Highlandcroft

Highlandcroft Plutonic Suite (NH*,ME*,VT*).

Ordovician, Late*
Geologic Province:
New England province*

Areal Extent:

Type Locality:
Type area: body of plutonic rocks 2 mi northwest of Littleton, Grafton Co., NH. Named from a large farm near Littleton (Billings, 1956).

Attean Quartz Monzonite, Fairlee Quartz Monzonite, Adamstown Granite, /Highlandcroft Granodiorite

Unit Name History:
Named Highlandcroft petrogenic cycle (Billings, 1934a).
Revised to Highland Croft magma series (Billings, 1934b).
Revised to Highlandcroft magma series (Billings, 1935).
Revised to Highland Croft magma series (Billings, 1937)
Revised to Highlandcroft plutonic series; Type area given; Overview (Billings, 1956).
Extended into VT (Johannson, 1963).
Extended into ME; Age modified (Cady, 1969).
Revised to Highlandcroft Plutonic Suite; Age modified; Isotopic dating (Lyons and others, 1986).
Age modified; Isotopic dating (Moench and Pankiwskyj, 1988).
Age modified (Moench and others, 1995).
NH State Geol. Map usage; Age modified; Isotopic dating (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