Berwick Formation  search
BTChronostratigraphic Units
 .Phanerozoic
 ..Paleozoic
 ...lower Paleozoic
 ....Berwick Formation
RTOrdovician
 Silurian
 New Hampshire
 Maine
 Merrimack Group
SNIn Merrimack Group. Probably Ordovician and Silurian. SW Maine and SE New Hampshire. Indexed with ages as applicable. Added to Thesaurus in 1989.