"DID THE ATLANTIC CLOSE AND THEN RE-OPEN?": TEACHING THE TECTONIC HISTORY OF PENNSYLVANIA BY (RE-)CONSTRUCTING THE TECTONIC (WILSON) CYCLE

To guide undergraduate geology students through the tectonic history of Pennsylvania, I have them use educational materials I’ve created, the PA DCNR’s PA State Parks, Forests and Geology Interactive Map as well as other online resources. These materials are integrated into a tectonic synthesis exercise that focuses on the Tectonic (Wilson) Cycle as revealed by PA bedrock geology. I use variants of this exercise in courses ranging from entry-level to advanced, but especially in Earth History. This exercise is synthetic and comprehensive, requiring introduction to and substantial scaffolding of information before and while being conducted.

In a nutshell, students first summarize the tectonic history of PA by deciphering a schematic geologic cross section I’ve constructed that encapsulates the geologic and tectonic history of PA in twelve events. Second, they reconstruct the Tectonic Cycle as evidenced in the geology of PA by using the description of events from the cross section. Event descriptions are rich with information, so I guide students through this process by reviewing the sequence of events depicted on the cross section and giving a short lecture that focuses on the Appalachian tectonic cycle. Outside of class, students are directed to refer to the online publication entitled “The Geological Story of PA” to help them complete this part of the exercise.

For the third part of this exercise, students use the PA DCNR interactive map to match twenty Outstanding Geologic Features in PA with their appropriate geologic descriptions. They locate and investigate specific sites across PA that are particularly linked to chronicling the tectonic history of PA. As a side, to encourage participation and aid understanding, this online map has searchable geology layers that provide portals for in-depth exploration into specific aspects of PA geology. Geology map layers can be highlighted to focus on the spatial distribution of these aspects. The map also provides location-specific clickable bedrock geology descriptions and a map legend that includes bedrock and surficial geology as well as other features. Finally, another possible activity is for each student to choose a particular outstanding feature, focus on the geology depicted there, and report back to class the geologic context and tectonic significance of that feature.