Pipe Creek Sinkhole facts for kids

The Pipe Creek Sinkhole is a super important place for finding fossils! It's located near Swayzee in Grant County, Indiana, in the middle of eastern North America. This special spot was kept safe because it got buried by something called glacial till, which is like dirt and rocks left behind by glaciers.

Workers at a limestone quarry (a place where they dig up rocks) found the sinkhole in 1996. A sinkhole is a hole in the ground that forms when a cave collapses. This particular sinkhole has given us amazing fossils from the Pliocene epoch, which was about five million years ago! Scientists have found bones and other remains of ancient camelids (like camels), bears, beavers, frogs, snakes, turtles, and even some types of rodents that no one knew about before. They also found two kinds of fish: bullhead (Ameiurus) and sunfish (Centrarchidae).

How the Sinkhole Formed

The Pipe Creek Sinkhole used to be an ancient wetland, which is like a swampy area. It formed when a limestone cave collapsed. This cave was part of a very old reef that formed during the Silurian period, hundreds of millions of years ago.

When the cave collapsed, it created a big, deep hole. This hole was about 75 meters (246 feet) long, 50 meters (164 feet) wide, and 11 meters (36 feet) deep. Water collected in this depression, turning it into a habitat for many plants and animals. Their remains were preserved there when the sinkhole was buried by glacial outwash and till during the Pleistocene Epoch. This was a long time ago, between two million and 11,000 years ago.

Why This Site is Special

Scientists already know a lot about the ecology (how living things interact with their environment) of the Pliocene period in North America, especially from fossils found near the coasts. However, the huge glaciers of the Pleistocene period destroyed or scattered most of the fossils in the middle of the continent.

But the Pipe Creek Sinkhole was different! It was buried by the glaciers and all the dirt and rocks they left behind. This protected the fossils inside. Because of this, Pipe Creek Sinkhole is the only known example of a Pliocene-era site in the central-eastern part of North America. It's like a time capsule!

Life in the Ancient Wetland

The ancient wetland at Pipe Creek was home to many different plants and animals. Some of these are now extinct (meaning they no longer exist), while others are still around today. The weather back then was warm and mild, but a bit dry. It might have been a mix of grasslands and forests.

Most of the vertebrate (animals with backbones) animals found here lived in the water. Leopard frogs, which are still common today, were especially numerous. Scientists also found bones from mammals, including an early type of rhinoceros (called Teleoceras), ancient dog-like animals (canids), pig-like animals (peccaries), and even a giant short-faced bear.

Discovering the Past

Researchers from the Indiana State Museum and several universities worked at the sinkhole. They received money from the National Science Foundation to help with their field work. They mostly finished digging in 2004, but they kept doing short digs once a year from 2005 to 2011. The last time scientists worked at the site was in 2014. They were sifting through soil that had already been removed from the sinkhole to find even more tiny fossils.