Martinsburg Formation  search
BTChronostratigraphic Units
 .Phanerozoic
 ..Paleozoic
 ...Ordovician
 ....Martinsburg Formation
RTVirginia
 Pennsylvania
 Maryland
 West Virginia
 New Jersey
SNMiddle and Upper Ordovician. In Pennsylvania, comprises (ascending) Cocalio Shale, unnamed and undifferentiated dark shales, Jonestown Beds (new), and Fairview Shochary Sandstones. Maryland, New Jersey, SE Pennsylvania, Tennessee, W Virginia, and West Vir