History of the Gray Fossil Site

The Gray Fossil Site was discovered in May, 2000 during road construction in Washington County near the community of Gray, Tennessee. The deposit is located in the southern Appalachian Mountains of east Tennessee, and provides a rare opportunity to study the paleoecology of southern Appalachia.

Finely layered, organic-rich sediment (note the microfault - total displacement is ~ 2-3cm).

Recovery of the rhino Teleoceras and the short-faced bear Plionarctos restricts the time of deposition to between 4.5 and 7 million years ago (late Miocene - early Pliocene). Current interpretations suggest that the site formed as a result of cave collapse, which formed a sinkhole into which the plants and animals fell to (eventually) become fossilized.

Core samples indicate that the deposit covers roughly 4-5 acres and is up to 40 meters thick. The highly laminated, organic rich, silty sediments are teeming with both plant and animal remains. Miocene-aged deposits have not previously been found within the Appalachians; therefore, this new locality provides a unique comparison to the classical Miocene records of Florida, the Gulf Coast and the Great Plains. Furthermore, the richness of this deposit will provide unprecedented quantities of fossil material for morphological analyses.

  The Gray Fossil Site is hypothesized to have originated as a sinkhole (typically the result of a collapsed cave). East Tennessee is rich in limestone, therefore, dissolution features (including sinkholes) are quite common. Evidence for the “sinkhole hypothesis” includes the presence of finely laminated sediment, poorly sorted gravel lenses, and large limestone boulders "preserved" within the sediments. Many of these boulders are quite large (size of a truck) and likely fell in from the bluffs that would have surrounded the newly formed sinkhole.

Originally, the sinkhole would have acted as a natural trap. Animals, such as the tapirs (who happen to have poor eyesight and would likely not have seen the hole) would have simply fallen in and been trapped by the steep walls. As the depression filled in with sediment and water, animals would have been drawn to it as a watering hole (continuing to contribute skeletal remains to the deposit via natural deaths, etc.)