The geology of our Commonwealth does not stop at ground level. In fact, one might argue that our state’s most interesting geologic formations are found beneath our feet. From stratigraphy and structure to porosity and permeability, Pennsylvania’s subsurface formations tell many interesting stories – of depositional environments, post-depositional alteration, the influence of tectonics, and much more. Oil and gas resources have been developed here for more than 150 years, so much of what we know about our subsurface geology, including basement rock, comes from the petroleum industry and oil and gas research conducted by the Survey and others. Information garnered through these efforts include drilling logs, downhole geophysical logs, and remote sensing and seismic survey data. The Pittsburgh office is the home of the Survey’s Petroleum and Subsurface Geology Section.