It’s all relative. Four hours on a Saturday for us humans is nothing compared to the vast period of geologic time. Yet the Geology of Philadelphia Bike Tour was a great break from our weekend routines and an eye-opener.
The winners of the Champion Circle spring promotional membership drawing recently enjoyed a semi-private, leisurely-paced 18-mile bicycle tour focused on the geology underlying and surrounding Philadelphia. We gathered in Old City on Saturday, June 10th and met our volunteer tour guide Ray Scheinfeld, a professional geologist as well as a fellow Champion Circle member.
Before we pushed off, Ray oriented us to basic geologic and hydrologic concepts and terms using handouts, maps, and baggies of rock/sand samples. We learned that Philadelphia is situated at the juncture of the Coastal Plain and the Piedmont and that Philadelphia’s flat in on the eastern side and rolling on the western resulted from continental drift and powerful plate tectonics. Flowing below our feet, but hidden, was Dock Creek, one of several creeks related to the ancestral Schuylkill River.
Another revelation was learning about the “Fall Line” – where the Coastal Plain and Piedmont zones meet and waterfalls occur up and down the East Coast. Think about that on your next bike ride or hike!
Arriving at the base of the Art Museum plateau, we examined the exposed bedrock and learned how fissures in the rock trap and move water that eventually finds its way out. Another rock formation further up Kelly Drive provided a great view of layers and folds of the rock while Ray explained the tools and methods geologists use to measure the “dip” (angle) of rock layers, and showed us how different rock type layers form within the primary rock.
Everyone who has ridden or driven along Kelly Drive knows there are multiple bridges spanning the Schuylkill River (Girard, Strawberry Mansion, Route 1 Twin Brides, and Falls). Ray emphasized how historical and modern engineers used geologic data to pick the best locations for anchoring the bridge footings.
The tour concluded with a snack and a peek at where the Wissahickon Creek joins the Schuylkill River. Here, Ray stressed how different the river level would look had Philadelphia not built the dam for the Fairmount Water Works in the early 1800s.
Champion Circle members form the stable bedrock for the Bicycle Coalition. Champions understand how important flexible, unrestricted funds are for boosting the Coalition’s ability to serve as a strong, steady advocate and educator.
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The Bicycle Coalition is grateful to Ray for donating his time and expertise, sharing geology jokes, and the stories about notable Philadelphia scientists and explorers. We thank Elana Benamy, Ray’s wife, for preparing the refreshments. We appreciate the enthusiasm, interest, and congenial company of the Champion Circle members and guests who participated. Additional thanks to the Philadelphia Canoe Club for allowing us to stop by and enjoy their historical location’s shade and amazing view.