GEOLEX database Geologic Unit: Mattapan Usage: Mattapan Volcanic Complex (MA*) Age: Precambrian* Proterozoic, Late* Geologic Province: New England province* Areal Extent: MA* Type Locality: Named from exposures in Mattapan, Dorchester district of Boston, MA (LaForge, 1917). Subunits: Twin Pine and High Rock Tuffs (MA) Unit Name History: Named (LaForge, 1917). Age modified (Kaye and Zartman, 1980). Age modified; Isotopic dating (Goldsmith and others, 1982). MA State Geol. Map usage (Zen, 1983). Members named; Isotopic dating (Thompson and Hermes, 1990). Overview; Age modified; Isotopic dating (Goldsmith, 1991). 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