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National Geologic Map Database

Geologic Unit: Ayer

Usage:

Ayer Granite (CT*,MA*)
Ayer Granodiorite (MA,NH*)


Geologic age:

early Silurian*


Type section, locality, area and/or origin of name:

Type area: from Hampstead, NH, through Ayer, north-central MA (Emerson, 1917).


AAPG geologic province:

New England province*


For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.

Asterisk (*) indicates published by U.S. Geological Survey authors.

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

Slash (/) indicates name conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).