Wissahickon Formation  search
BTChronostratigraphic Units
 .Phanerozoic
 ..Paleozoic
 ...Wissahickon Formation
RTVirginia
 Pennsylvania
 Maryland
 Delaware
 lower Paleozoic
 Glenarm Series
SNLower Paleozoic (?). Prevalent structure is schistose. Delaware, N Maryland, SE Pennsylvania, and Virginia.