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Pipe Creek Sinkhole
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, preserved because it was buried by glacial till. 〔For a general description of the transport and deposition of glacial sediments, see 〕 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. Discoveries have been made there of the remains of camelids, bears, beavers, frogs, snakes, turtles and several previously unknown species of rodents. Two fish taxa, bullhead (''Ameiurus'') and sunfish (''Centrarchidae''), have also been found there.
==Origin and importance==
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.
While the ecology of the Pliocene in North America is well-known from fossil discoveries in other places, notably coastal sites, the Pleistocene glaciers destroyed or scattered most of the fossil remains in the continent's interior. 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.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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