CONTINENTAL-MARINE MISSISSIPPIAN RELATIONS IN NORTHERN PENNSYLVANIA

Abstract

The marine Mississippian of northwestern Pennsylvania meets and merges in north-central Pennsylvania with the continental Mississippian spread from the northeast. At their junction, the two facies are confined between the overlying Olean or Pottsville spheroidal-pebble conglomerates of the basal Pennsylvanian and the underlying Devonian. The latter is represented by the Mount Pleasant red shale of the continental Catskill facies to the east and the youngest marine Devonian, the Oswayo formation, to the west. The marine Mississippian consists of the Knapp formation including the Kushequa shale and Marvin Creek “limestone”. The Knapp is largely composed of sandstones and conglomerates, the latter distinguished by their discoidal, milky quartz pebbles and occasionally a jasper phenoclast. The marine Mississippian yields Kinderhook fossils. The continental Mississippian, carrying the Triphyllopteris flora, consists of the gray Pocono sandstones and pebble beds which to the east are overlain by the Mauch Chunk red shale, not recognized in north-central Pennsylvania. In the region of marine-continental transition, the Mississippian system is represented by approximately 150 feet of beds. The marine fossils gradually disappear eastward as the discoidal-pebble conglomerates and sandstones of the Knapp merge with the Pocono sandstone and conglomerate.