GEOLEX database Geologic Unit: Fish Brook Usage: Fish Brook Gneiss (MA*) Age: Precambrian* Proterozoic, Late* Cambrian Ordovician* Geologic Province: New England province* Areal Extent: MA* Type Locality: In vicinity of Fish Brook, Boxford, MA (Castle, 1965). Unit Name History: Named (Castle, 1965). Age modified (Castle and others, 1976; Bell and Alvord, 1976; Goldsmith, 1980). Isotopic dating; Age modified (Olszewski, 1980). MA State Geol. Map usage (Zen and others, 1983). Overview, age discussed (Goldsmith, 1991). Isotopic dating; Age modified (Hepburn and others, 1993). Isotopic dating (Hepburn and others, 1994). Note: If you need more information, please contact Nancy Stamm (nstamm@usgs.gov). 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 URL http://ngmdb.usgs.gov/ngmdb/ngm_catalog.ora.html Database project personnel Last modified: 7-Jan-2007