Post-glacial tectonism and bluff erosion in northern Erie County, Pennsylvania, USA

Abstract

This one-day field trip will visit northern Erie County in northwestern Pennsylvania, USA, and is divided into two parts. The first part will highlight brittle and ductile deformation preserved in Upper Devonian bedrock. It is possible that this deformation occurred in relation to the Alleghenian orogeny during the late Paleozoic. However, some of this deformation displays possible evidence of postdating Wisconsin glaciation, but this interpretation is speculative and based largely on possible topographic disruption of Quaternary river terrace deposits. Morphologic characteristics of outcrops in creeks that expose these tectonic structures will be used as a starting point to discuss structure origin, timing, and their implications. The second part of the trip will visit Erie Bluffs State Park (EBSP) and will examine ongoing mass wasting of bluffs along the southern Lake Erie shoreline. The timing (as determined from dendrochronological analyses) and styles of mass wasting that have occurred at EBSP will be discussed and compared to two other locations along Pennsylvania’s Lake Erie shoreline. An appended road log serves as a geologic guide to the features and processes highlighted on this trip.