In 1968, John W. Leap and workers at a nearby peat bog discovered the bones of a large mastodon that died about 12,000 years ago. These large, tusked mammals (Mammut americanum) lived throughout North America from 5.2 million to 10,000 years ago. The Marshalls Creek specimen, now in the collection of the State Museum of Pennsylvania in Harrisburg, ranks among the most complete mastodon skeletons found on the East Coast.