This field trip provides an overview of both the geology underlying the city of Philadelphia and the hydrology of the Schuylkill River watershed. Philadelphia is located at the contact between two major East Coast physiographic provinces, the New Jersey Coastal Plain and the Piedmont. The Piedmont rocks are examined during this field trip. In this area, the Piedmont exhibits low to moderate relief and is underlain by folded and faulted sedimentary and metasedimentary rocks of early Paleozoic age. These rocks are interpreted to represent the collision of a magmatic arc with a continental landmass and adjacent forearc basin sediments during the early Paleozoic; they are intensely deformed and metamorphosed to the amphibolite and granulite facies. The Piedmont rocks appear in the type section of the Wissahickon Formation, which will be the geologic focus of this field trip. The hydrology of the Schuylkill River and one of its major tributaries, Wissahickon Creek, will also be discussed during the trip.
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The 2006 GSA Annual Meeting in Philadelphia provided a unique venue for the geologic and historic exploration of the Middle Atlantic States. Excursions into Geology and History is a collection of 13 papers and accompanying field guides that explores topics ranging from fossil plants of the Pennsylvania Anthracite basins, to the use of slate as a building stone, to the structural geology of Appalachian orogen transects, to coal basin mine fires, to the geological influences on the outcome of the Civil War battle at Gettysburg, America’s most hallowed ground. The book will prove to be a valuable educational resource for geologists and historians alike.