Detailed mapping of “clean” sandstones of the Hampshire and Pocono formations of northern West Virginia illustrates paralic facies of north-south trend, intersected by belts of sandstones with east-west trends representing fluvial and tidal channel facies. The strike-trending paralic sandstones commonly have maximum thickness of 20 to 30 ft, and successive isopach maps of individual sandstones indicate irregular shifts that are interpreted to represent embayed shorelines advancing and retreating in uneven fashion. These small-scale changes affect small segments of the shoreline and probably result from fluctuations in sediment supply related to upstream avulsion or stream capture. Isolith maps of multiple sandstones of intervals such as the Fifth, Fourth, Gordon, Thirty-foot and Fifty-foot, show greater shoreline shifts probably due to sea level changes.
Regional cross sections through the Catskill clastic wedge show vertical stacking of shoreline sands in a belt with north-south trend. This preferential zone of subsidence is bounded on the west by the eastern margin of the Rome trough, and on the south by the northern edge of the Pocono dome. This interpreted subsidence increases southward toward the Pocono dome, suggesting basement sub-blocks with southerly tilt.
Dip-trending sandstones show southeast-northwest trends with a large degree of vertical persistence. Major fluvial axes occur approximately every 40 mi along strike and may also be a reflection of basement structure.