ABSTRACT This field guide reviews the coastal and engineering geology of Presque Isle State Park, a 9 km 2 flying sand spit located on the NW Pennsylvania bluff coast of Lake Erie on the North American Great Lakes. Much of the spit’s shoreline is armored with offshore breakwaters, groynes, and riprap, and lakefront beaches have received regular beach nourishment for more than half a century. The guide describes a series of eight field-trip stops along this dynamic and anthropogenically modified depositional landform. The stops progress downdrift along the Lake Erie side of the spit to the North Jetty at its downdrift terminus, returning along its Presque Isle Bay side to where the spit joins the mainland bluffs.

ABSTRACT This field guide reviews bluff retreat processes and rates; hazards; mitigation efforts; and stakeholder challenges along the erosional NW Pennsylvania bluff coast of Lake Erie, the shallowest and southernmost of the North American Great Lakes. Seven stops progress downdrift to the northeast along a large coastal littoral cell, the western Erie County littoral cell (WECLC), beginning at the Pennsylvania-Ohio state line and finishing where the WECLC transitions to the Presque Isle littoral cell near downtown Erie. In this sediment-starved cell, spatially variable bluff-crest retreat rates over the past half-century average ~0.25 m/yr along the updrift sector of the WECLC and ~0.1 m/yr along the downdrift sector. Much of the retreat is the result of small- and moderate-sized rotational slumps and less frequent but larger translational slides. Key attributes driving bluff retreat include bedrock elevation, beach volume, wave impact hours at the bluff toe, and groundwater flux through the bluff face.