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What started out as a routine highway construction project in Upper East Tennessee has developed into a fossil discovery of major scientific proportions.
The Tennessee Department of Transportation began widening and straightening a two-lane road south of Gray Station in Washington County near Daniel Boone High School. The project moved along at normal speed until the contractor uncovered a deposit of soft black clay in the normally hard red clay in May 2000.
Since the soft clay would not support the roadbed without special treatment and since they had never seen any soil like this before, the contractor called in TDOT geologists from Knoxville for technical advice.
As it turned out, Harry Moore, a geologist in the Regional Geotechnical Engineering Office, and lifelong fossil collector was the perfect person for the visit. What Harry, Larry Bolt, TDOT geologist and Martin Kohl, TDEC geologist found in the layers of soft black clay was a large number of mineralized animal bones and plant remains.
The bones were in perfect condition; they looked like they had come from an animal that had died recently but they were heavier than normal.
The calcium in the bone had been chemically replaced with other minerals over a long period of time. Most of the bones appeared to be from a pig-sized animal but the geologists knew they did not have the expertise to identify what species were represented.
Luckily for them, the University of Tennessee Department of Anthropology in Knoxville had the experts they needed. Dr. Walter Klippel and Dr. Paul Parmalee have dedicated their professional careers to the identification of animal bones from archaeological sites. They also have extensive collections of the skeletons of animals from over the world to which they can compare unknown pieces of bone.
Most of the pieces of fossilized bone came from an animal identified as a tapir. Tapirs have a long snout, a chunky pig-like body and long thin legs. Although they look like an animal designed by a committee, the design has worked successfully for millions of years.
Tapirs appear for a long time in the fossil record and several species still live in South America. They travel in herds and roam in forested hilly terrain.
The geologists examined the black clay deposit and found that it was layered in the same manner as pond or lakebed sediments. These lacustrine (or lake formed) sediments accumulate in slack or still water from silt that sinks to the bottom. Leaves and twigs also sink to the bottom adding to the organic ooze. But in this case it appeared that other animals had also sunk to the bottom as well.
In addition to the tapir bones, they found turtle shells and most unexpectedly a toe, part of a pelvis and tusks from an elephant.
At this point in the discovery process, highway construction was still going on. After each scrape with the bulldozer or pan, the contractor would allow the geologists and archaeologists to dart in and collect newly exposed pieces. This grab sample process was not conducive to good scientific knowledge and explanation, but they could tell already that this was a very unusual fossil site.
Had the discovered items been Indian artifacts and human bones, TDOT and contractor officials would have known to stop work and have the find examined by the Division of Archaeology staff. But the fossils were so different that it took the TDOT legal counsel to discover in the law books that the State Archaeologist also has jurisdiction over paleontological remains on state property.
At this point, I was called to evaluate what was going on. In my 32 years of archaeological experience I have looked at some unusual and weird things, but fossil animal bones were not part of the mix. But I was able to get the construction stopped in the fossil bed area of the roadway until we could see what was what.
We also formed an advisory working group of specialists including geomorphologists, structural geologists, paleontologists, zooarchaeologists (specialists in studying animal bones) and construction engineers to collectively decide the best course of action.
How big was the fossil deposit and how deep was it were the key questions. We could see the dark layered clay in the road cuts so we had a good idea of the lateral extent in three directions. TDOT provided a drilling rig to determine the depth. The clay was over 100 feet deep below the road cut and the roadbed was about 30 feet below the original hilltop.
This was not an ordinary pond. Drilling determined that the deposit is about four acres in size. On the edges of the deposit in the road cut we could see that the layers of sediment containing the fossils and plant remains were tilted at a 30 to 40 degree angle. In a normal pond, these layers are horizontal. After the layers had been deposited with their content of animal bones and plant material, some force had rearranged them. The most logical and simplest explanation to date is the pond was a sinkhole with a cave underneath.
At some point in the history of the site, the pond layers subsided into the cave below thus making it much deeper than before and tilting the once horizontal layers of silt and clay.
By this time, we (the geologists and archaeologists) thought we understood about how old the site was. The elephant (mastodon?) and tapir and turtles all occur in fossil deposits in Tennessee at the end of the Ice Age or Pleistocene around 15,000-30,000 years ago. We were not finding some of the more common Ice Age animals, but in paleontology you take what you can get.
There was one puzzling identification however. Rick Noseworthy, a TDOT environmental specialist on the job, found a large portion of what Dr. Parmalee identified as an alligator or crocodile skull. That started to raise doubts about our working hypothesis of a Pleistocene date. A rhino expert in North Dakota eliminated the supposed Pleistocene date idea with the identification of several pieces of Miocene rhinoceros skeleton. This particular genus Teleoceros sp. became extinct in North America around 4.5 million years ago!
Other geologists doing specialized soil magnetism sample analyses corroborated the findings. Our site was suddenly older and much more special. Instead of a fairly common Pleistocene site, the Gray Fossil site as it was being called now, apparently dated back to the Miocene. Sites from this time period site are very rare in Eastern North America.
Now we had a real dilemma, the highway was still under construction except where we were working. Our original plan was to excavate the fossils under the roadway, but now with the data from core drilling samples and the significance of the fossil remains, that plan did not seem to be not such a good idea.
As it turns out, Governor Don Sundquist had the answer to the dilemma. Governor Sundquist had taken geology in college and liked it. When he heard about the fossil site in Gray, he wanted to see it for himself. He went to Johnson City with TDOT Commissioner Bruce Saltsman, TDEC Commissioner Milton H. Hamilton and Deputy to the Governor Justin Wilson. Governor Sundquist had a hands-on appreciation of the significance of the site and saw the scientific, educational and the tourism potential that such a unique site offers. As a result of his visit, he directed TDOT engineers to find a way that long-term fossil excavations and preservation could be accomplished.
TDOT engineers designed a geogrid reinforcement that would carry the load of the road traffic over the fossil deposit but this action would seal the fossils from further work. They also designed a low bridge spanning the fossil deposit but that option required support piers in the center of the site. Governor Sundquist selected the third option, which was to relocate the road about 500 feet to the north to avoid the deposits. The selected solution allows the needed road construction to resume and preserves the fossil site for future research and public education.
Although an initial local newspaper report that we had found the skeleton of a beaver the size of a pickup truck was in error, there has been a large amount of local public interest in the discovery. Numerous articles on the finds have appeared in local and Knoxville newspapers. A Friends of the Gray Fossil Site group has formed. Due to the close proximity of I-181 and I-81 and East Tennessee State University just down the road, the site can be a site of major paleontological research efforts and a site you can visit to see it happening.
Current plans have ETSUs Department of Geology managing the site and coordinating the geological and paleontological work, but researchers from all over the world will be interested in conducting research at the Gray Fossil site. Future plans will include a fossil research building and exhibit. The main attraction will be the wonderful collection of fossils yet to be discovered and the careful excavation that can make East Tennessee of five million years ago come alive.
(Nick Fielder is the state archaeologist and director of the Division of Archaeology. Harry Moore is a geologist with TDOT and manages the regional Geotechnical Engineering Office in Knoxville.)
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