THE MARCELLUS SUBGROUP COMPOSITE TYPE SECTION, IN THE TYPE AREA, CENTRAL NEW YORK STATE

The type area for the Marcellus subgroup, a major target for gas-action in the Appalachian Basin, is located in the town of Marcellus, New York. The Marcellus outcrops in several road and stream exposures, but the type section designated by Cooper in 1930 is incomplete; the Union Springs Formation, a major gas producing unit of the subgroup, and the lower Oatka Creek Formation are covered. A new composite type section that incorporates the original section in Jackknife Ravine, as well as another nearby stream, contains a nearly complete exposure of the Marcellus. The composite type section incorporates the Union Springs Formation which consists solely of the Bakoven Member, the lowermost unit of the Marcellus. The Bakoven unconformably overlies the Seneca Member of the Onondaga Limestone marking the drowning of the Eifelian carbonate ramp and the base of the Hamilton Group. The Oatka Creek Formation, the first complete depositional sequence of the Hamilton Group, consists of five members, the Hurley, Cherry Valley, East Berne, Chittenango, and Cardiff. The Mottville Member of the Skaneateles Formation overlies the Cardiff marking the upper contact of the Marcellus subgroup. The total thickness of the Marcellus in the type area is approximately 83 meters.