Trenton Group  search
BTChronostratigraphic Units
 .Phanerozoic
 ..Paleozoic
 ...Ordovician
 ....Middle Ordovician
 .....Trentonian
 ......Trenton Group
RTVirginia
 Ohio
 Pennsylvania
 Vermont
 New York
 Georgia
 Michigan
SNStandard section of group comprises (ascending) Rockland Limestone, Hull Formation, Sherman Fall Formation, Cobourg Formation, Collingwood Shale, and Gloucester Shale. In Georgia, Michigan, N Ohio, New York, Vermont, and W Virginia.