Two decades ago Joseph Barrell published his now classic discussion of the Devonian delta of the Appalachian geosyncline. In twenty years new data have accumulated which modify details and alter correlations, and also strengthen the original thesis. As a further investigation of the problem, it is now proposed to trace the early Chemung shore line across Pennsylvania.
The author has devoted practically the entire past four years to a study of the Devonian of Pennsylvania, and has published some preliminary observations regarding the Upper Devonian and its problems.1 The progressive off-lap of the nonmarine, or Catskill, facies of Devonian sedimentation in Pennsylvania has been described from studies of a series of sections from north-central New Jersey to southwestern Pennsylvania (Fig. 1). It has been shown that the Catskill facies commenced in early Hamilton time in the east, and continued into Chemung time2 in the southwest. Additional data now make . . .