Figure 11. Geologic map of central Pennsylvania showing approximate locations of the seismic-reflection profiles (from Berg, 1980). Formation symbols are explained as follows: Or, Reedsville Shale; Obe, Bald Eagle Formation; Oj, Juniata Formation; St, Tuscarora Formation; SC, Clinton Group (predominantly Rose Hill Formation); Sbm, Bloomsburg Red Beds and Mifflintown Formation, undivided; SwC, Wills Creek Formation; DSkt, Keyser and Tonoloway Formations, undivided; Doo, Old Port Formation and Onondaga Limestone, undivided; Dh, Hamilton Group; , Devonian, Mississippian, and Pennsylvanian formations, undivided. Solid heavy lines indicate faults. Dashed lines show the location of the Susquehanna lateral ramp. From Pohn and Coleman (1991), modified from Berg and Dodge (1981).