The Pipe Creek Sinkhole near Swayzee in Grant County, Indiana, is one of the most important paleontological sites in the interior of the eastern half of North America.
[1] Uncovered in 1996 by workers at the Pipe Creek Junior limestone quarry, the sinkhole has yielded a diverse array of fossils from the Pliocene epoch, dating back five million years.
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 Pipe Creek Sinkhole, however, was buried by the glaciers and the debris they left, making it the only known Pliocene example in the central part of the eastern half of the continent.
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.