I created this image to better understand the geologic structure beneath north-central Pennsylvania and the processes that shaped it. The view looks east–northeast and represents approximately eight miles in width and three miles in depth. Five well pads are visible at the surface, with gas wells extending downward into the Marcellus Shale.

The deepest metamorphic rocks in the image formed more than one billion years ago along the eastern margin of North America. Hundreds of millions of years later, sedimentary layers accumulated over a span of roughly 160 million years as continents gradually converged to assemble the supercontinent Pangaea. During this time, repeated mountain-building events—the Taconic, Acadian, and Alleghenian orogenies—uplifted vast highlands. Over time the highlands were eroded and portions of sediment were transported westward into an inland sea and deposited within the Appalachian Basin.

The sedimentary sequence beneath the site includes limestone, shale, and sandstone. Fossils such as trilobites, brachiopods, and early plant life help date these layers and record ancient marine and coastal environments. Some units, including the Marcellus Shale, contain organic material derived from microscopic plant and animal remains. Over time, burial, heat, and pressure transformed this organic matter into oil and natural gas.

Today, gas generated through these long geologic processes is produced from the Marcellus Shale, approximately one mile below the surface as shown in this image.

Photo-geologic composite created through field photography, geologic interpretation, and digital compositing.