Paleontology and geology
During the Permian, the continents were colliding to form the supercontinent Pangea. One of these collisions resulted in a mountain-building event, the Alleghenian Orogeny, that formed the modern Appalachians. The vast swamps of Pennsylvania of the Carboniferous dried up as the seas drained off the rising landscape. As the Permian was primarily a time of erosion in the state, there are few outcrops of this age in Pennsylvania. However, ostracodes and a few tiny fish teeth have been recovered from the Permian of Green and Washington Counties in southwestern Pennsylvania.