Digging up Dirt: Gray Fossil Site

Story and photos
by Kathleen Walls

They are uncovering treasures in Washington County, Tennessee. It's not the kind with gold and silver, but it's more important because it's telling us what life was like here in the early Pliocene Epoch between 4.5 and 4.9 million years ago.

Gray Fossil Site

Gray Fossil Site in Gray, a suburb of Johnson City, was discovered in May 2000 when the Transportation Department was grading a big hill to put in a road. I visited recently and met with Matthew Inabinett, the paleontologist who is the Collections Manager at the site. He told me about the site and took me around for an in-depth visit. He told me how it began. "They took about 40 feet of what we call overburden, just overlying sediments that are not related to the site, off the top of this hilltop, and they found this black clay unit."

Mathew explained that it was not scientifically earth shattering yet. "This really sticky, wet, black clay was something with these nice layers and it was nothing that any of the geologists had seen around here before. So road construction kind of paused for a time while geologists were running structural tests basically to see if we could build a road on this or is it just going to give way in five years or something. Is this going to be stable? And while the construction was paused, fossils were found."

They found mastodon and tapir fossils. That made it important. Still, at first, they believed it was an Ice Age site. But when they found an alligator skull, they knew it wasn't the latter part of the Ice Age, because it was too cold for alligators 20,000 years ago during the cold period of the Ice Age.

It was when they found the first complete rhino in 2004 at the site, everything but one toe bone, they knew it was much earlier. Matthew said, "This animal here was the clincher that it was a Miocene or Pliocene age.”

At one time rhinos were common across much of the United States, but four and a half million years ago, rhinos disappear across the whole continent.

I asked "Why?"

He said, "Presumably, we know this is the time when North America is starting to get cooler and drier. Forests are giving way to a more open country. A lot of grassland habitats are developing." He explained how this fossil was such an important discovery. "We think today that these rhinos at Gray are some of the very last ones in North America right before they die out. And what's different about this rhino compared to a lot of its relatives, it's what we would call a barrel-bodied rhinoceros, teleoceros. There's several different species of them and this particular species found at Gray is unique to the fossil site. It hasn't been identified anywhere else."

That is a pretty big WOW! to me, and a good reason to visit Gray Fossil Site. The site was once a pond where these prehistoric animals would come to drink, so there are many different kinds of fossils here. Matthew took me to view the dig and research areas of the site. You can see the same when you visit and take a tour.

One item we saw on display was Big Red, a young adult male of an extinct type of red panda called Pristinalaris pristilii, which has only been found here at the Gray Fossil Site. He would have weighed about 30 to 35 pounds. The example on display is a model as the real bones are in storage to protect them.

We viewed the dig where workers were carefully digging through one small section. Then we moved to the washing troughs.

Next stop was the prep lab where scientists were cleaning up some of the fossils that come out of the ground and beginning to process of putting the complete fossil together. Usually complete fossils are not dug at one time, so they use a special glue that is reversible. When a new piece is found, they dissolve the glue at that place in acetone and then add in the new piece. They are also the first fossil prep lab to use 3D printing in archival materials technique as part of the preparation. If they find one side of a skull, they scan it on a 3D scanner, flip it over and printed it out, so it's a mirror of the original. They use the same material as the glue.

We visited the storage section where all the original fossil remains are stored. I got to see the entire set of bones of the mastodon. They took up an entire section.

Hands On! Discovery Center

The Hands On! Discovery Center first opened in August 2007. It's a great tool to help both children and adults understand the fossil site. Sarah gave me a tour of the museum and the adjourning garden and wing where children's camps are held.

Paleontology Climbing Tower, a three-story interactive tower, is one of the first things you see on entering the museum. Here you can discover the fossils found at the site on each level. You can see and touch actual 3D replicated models of the fossils. This structure is the only of its kind in the United States.

The Miocene Exhibit Hall showcases samples of the kind of fossils being unearthed at the dig site. There's a Discovery Lab where you can do a hands-on experiment. The Scheu Family Exhibit Hall & Art Studio in the General Shale Learning Center hosts leaning camps for children.

The Discovery Garden is a shady haven of native trees, shrubs, grasses, vines, and flowering perennials. You'll find butterflies and other animals there. Many of the plants in it were also found here five million years ago when this site was a watering hole that attracted the animals that are being uncovered today. There is also an outdoor fossil replica dig pit and two Seed to Table exhibits.

There are not a lot of places you can see an active dig site in the US, so plan to experience Gray Fossil Site and the Hands on Discovery Center for yourself.

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