Pipe Creek Sinkhole
Pipe Creek Sinkhole preserves an ancient wetland. It was created by the collapse of a limestone cave in a Silurian reef formation. That left a steep-sided depression about 75 meters long, 50 meters wide and 11 meters deep. When water collected in the depression, it became the habitat of the plants and animals whose remains were preserved there when the sinkhole was buried by glacial outwash and till during the Pleistocene Epoch, two million to 11,000 years ago.
The ancient wetland was home to a large and dense plant and animal population that includes both extinct and extant forms. The climate was warm and temperate, but somewhat dry, possibly supporting a grassland-forest transitional zone. The preserved vertebrate fauna are dominated by aquatic species, particularly leopard frogs, which are still common throughout the United States. Mammalian finds include an early rhinoceros canids, peccaries and shaort faced bear. Backed by a grant from the National Science Foundation, researchers from the Indiana State Museum and several universities substantially completed field work at the sinkhole in the summer of 2004, but there was about one weeklong dig a year from 2005 to 2011. Which probably was the last work at the site took place in 2014, with scientists and volunteers screening soil previously removed from the sinkhole.