UPPER DEVONIAN STRATIGRAPHY, WEST CENTRAL ERIE COUNTY, NORTHWEST PENNSYLVANIA

As an outgrowth of several years of undergraduate study culminating with a seminar, we have studied the Upper Devonian bedrock from the Northeast Shale to the top of the LeBeouf Sandstone. Although regional correlations of the Upper Devonian from southwest New York to northeast Ohio already have been made, much of the local bedrock still remains undifferentiated. The goal of our study, therefore, is to provide a detailed stratigraphic study in west central Erie County. We studied sedimentological and paleontological content for nine measured sections ranging in thickness from 150 feet to over 500 feet extending nearly east to west across four USGS 7 ½' topographic quadrangles to refine the existing understanding of the deposition environments.

Similar to previous research, we find that the Cruziana/Skolithos Ichnofacies of a warm, shallow marine environment best describe the Upper Devonian of west central Erie County. Our study also suggests that a mixed clastic, tidally influenced, embayed shoreline existed throughout the Late Devonian in our study area. Beginning with and including the Northeast Shale, five distinct facies exist: nearshore tidal, restricted bay (at times nearly subaerial), nearshore tidal/less restricted shelf, tidal shoal, and shallow, open shelf (associated with the LeBeouf Sandstone). Several small-scale transgressive/regressive cycles in an overall regressive phase terminated with a regional transgressive event marked by the deposition of the blanket sands of the LeBeouf Sandstone.