Geology of Gray Fossil Site

Sinkhole at Gray Fossil Site

Reported by Paul

        In May 2000, a cache of old bones was dug up during road construction in the Gray community in Tennessee, near the Appalachian Mountains.  This provided not only great bones, but also a rare opportunity to study paleontology in southern Appalachia. A man by the name of Larry Bolt noticed unusual landscape in the road construction and wanted to take a peek at it.

         When he found fossils, the former author was searching for fossil aquatic life.  The men dug each day and the excavators found that there were fractures in the ground, meaning that a cave collapse had happened.

           A fossil in the cache was either in black, grey, white, or buff colored dirt. The first fossil found was about 10 meters deep into the sinkhole. Between the bones and dirt there were boulders the size of trucks. (Imagine trying to cut through that!)

          Some aquatic invertebrates found in many of the layers of dirt were snails, ostracods, and very small clams.  The vertebrate bones found after earth operations  have been mostly tapir and turtle bones, in some cases Crocodilian vertebrates have been found too!  Snakes, frogs, a bunch of insects, and a distal phalanx found from a bear was discovered!

The short-faced bear was found along with the red panda and the Teleoceras rhinoceros. Some of the bones date back to seven million years ago! Some think the site resulted in a cave-in, which made a big sinkhole. Plants and animals eventually fell into the sinkhole and got pressurized and fossilized. The area of the cache was four to five acres with a depth of 40 meters thick.  The cache underground was highly laminated. The soil was rich along with the dead animals preserved in the ground.  The soil contained quantities of fossil material for morphological analysis. This cache is the only sinkhole found so far in the Appalachian region.

             The site is believed to have originated from a sinkhole (from a cave collapse). There is a lot of limestone in Tennessee and caves form from that mineral. This could make sinkholes common.  The evidence of the "sinkhole hypothesis" includes the presence of finely laminated sediment, and large limestone rocks preserved in the sediments.  A lot of these boulders ( some the size of a truck!) likely fell into the cave entrance, which possibly made the cave fall inward and start a new sinkhole.

            Tapirs have bad eyesight and a sinkhole wouldn't seem any more different than normal ground when they first saw it.  When an animal fell into a sinkhole, it would die of not being able to breathe, so that means there must have been a liquid in the sinkhole. Underground (under pressure), it will fossilize. 

              The Gray Fossil Site is located at the Valley-and-Ridge province in upper East Tennessee.  Some Gray Fossil Site bones are found at the local Hands-On Museum in Johnson City, Tennessee.

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