Paleontology and geology
Ice sheets covered much of Pennsylvania during the Late Quaternary. Sediments left by the melting ice can be found in many areas, particularly in the northern parts of the state. Mastodons, ground sloths, and saber-toothed cats roamed the ice-free regions of the state. Fossils of plants, such as mountain avens, willow, and sedge, help paleontologists decipher the complex climatic history of Pennsylvania during the Quaternary.