REPORT OF ATYPICAL KARST IN THE DEVONIAN CATSKILL FORMATION, NORTHEASTERN PENNSYLVANIA

The Upper Devonian Catskill Formation of Pennsylvania’s northern tier (Glaciated Low Plateau Section) contains calcareous beds, that when weathered, display karstic features. These beds are intraformational conglomerates, a poorly-sorted hodgepodge of non-calcareous and calcareous clasts, of largely paleo-erosional and paleo-pedogenic origin. These units can occur as individual beds or are intermixed with near-horizontal to low-angle, tabular and trough cross-bedded sequences. The regionally predominant north-south, east-west jointing, coupled with dissolution along bedding discontinuities and mass wasting processes provides the impetus for cave passage development. Although the occurrence of these features is generally limited to the rims and steep-sided slopes of incised stream valleys, it is assumed that their topographic relief in abutting lowlands is masked by the infilling of the weathered features by glacial outwash. These units have been overlooked as major karst players due to their oftentimes minimal bedding thickness and compositional admixtures with non-calcareous sedimentary sequences. Their inclusion as karstic is somewhat debatable as they partially fit into established definitions for carbonate and evaporite karst.

Subsidence potential for the Catskill of northeastern Pennsylvania is considered relatively low, however, there is increased potential for dispersal of contaminants within groundwater due to enhanced development of secondary porosity and permeability along these weathered zones.