The bedrock geology of the 7.5-minute Nashua South quadrangle consists primarily of deformed Silurian metasedimentary rocks of the Berwick Formation. The metasedimentary rocks are intruded by a Late Silurian to Early Devonian diorite-gabbro suite, Devonia
Walsh, Gregory J. gwalsh@usgs.gov,Jahns, Richard H.,Aleinikoff, John N. jaleinikoff@usgs.gov. Bedrock geologic map of the Nashua South quadrangle, Hillsborough County, New Hampshire, and Middlesex County, Massachusetts. 2013-01-01.