3D radar-computer 'digs' for Lost ColonyBY ED BECKLEY | SENTINEL CORRESPONDENT
Radar Tomography Field Engineer Mike Meide checks his computer screen for radar signals indicating underground images at Fort Raleigh. Meide picked up much radar feedback showing that there is something buried below, but archaelogist Eric Klingelhofer noted it might be park utilities or relics from a farm that was on the site for many years. (Ed Beckley | Sentinel) When doctors want to see a body's organs they use an magnetic resonance imaging machine (MRI) to view beautifully clear images of what's inside.
When archaeologists want to see what's below the surface of the earth they are now beginning to use a similar technology called computer-assisted radar tomography (CART).
An archaeologist with the First Colony Foundation was on site at Fort Raleigh Saturday with CART engineers testing the advanced ground penetrating system. Their hope is that CART will prove to be a viable tool to help find artifacts from Sir Walter Raleigh's 16th Century colonies in the future.
The First Colony Foundation comprises a team of top archaeologists who in recent years discovered the expanded Jamestown, Va. settlement. The group also is a partner with the National Park Service in search of the Elizabethan presence on Roanoke Island. It has dug its share of holes along Roanoke Sound the past couple of years.
"The search continues," said Park Ranger Rob Bolling, as the CART rolled along the park's eastern parking lot near The Lost Colony production box office. Only this time, nobody's hands were getting dirty.
"It looks like a lawn mower," said the Foundation's vice president of research and archaeologist Eric Klingelhofer, who set up the project.
In fact, it partially is. The system uses a fixed array of radar transmitters and receivers which lay atop a rolling cart. The cart is only about a foot off the ground. A modified commercial lawnmower pushes the device while its radar transmitters fire into the ground. Its receivers then pick up signals reflected back by subsurface objects. The data displays and is stored in a computer located near the lawnmower's driver seat.
On this day, Radar Tomography Field Engineer Mike Meide of Jacksonville, FL, was operating the CART vehicle and collecting data from unseen objects under the parking lot blacktop. Co-worker John Krause of Tallahassee stood nearby operating a laser-tracking machine that resembled a surveyor's tripod. Both men work for Witten Technologies, Inc., developers of the CART system. Krause's laser-tracker robotically followed and marked the location of the CART every six feet. This would allow Witten's proprietary software to create a map showing what the CART found, and where. The software would not only accurately pinpoint where the reflections took place, it would convert the signals into three-dimensional pictures of what the underground objects look like. It would present the images clearly and in almost perfectly accurate size and shape, the men said.
Meide seemed confident that the sandy soil would prove satisfactory for the test. "The worst soil is clay, which absorbs radar energy. Sand lets the energy pass through it," he said. During the interview, Meide said, "There's something down there." It was evident from radar waves on his computer screen that something deeper than five feet was reflecting upward. Klingelhofer didn't get excited. He already knew there were park utilities underground, and the site also had been a farm for many years. Union Civil War soldiers had an encampment there, as well.
Klingelhofer's teams had dug trenches adjacent to this area in past years. However, this would be the first time archaeologists would get a look at what was lurking under the hard surface of the huge parking lot nearby. "There's nothing instant about this," he said.
Even though Meide said there might be something to look at next week, the archaeologist reserved judgment.
Moments later it began to rain, which would have postponed another test on the dirt trail just north and east. Bolling said a ground radar scan in the 1980s had picked up at least one rectangular-shaped anomaly in the woods, consistent with a grave. He said that many people died during a 1918 influenza epidemic, and park officials never found the graves in the area they thought they would be. He couldn't speculate what CART might find there.
Klingelhofer said the CART has "great potential," and he was "very enthusiastic about it, but we have to run these tests. If this turns out to be an appropriate tool, then we would raise money for its use here." Those wishing to make a tax-deductible donation to the First Colony Foundation can send checks to 1501 Cole Mill Rd., Durham, NC, 27705.
Bolling said the park service is making every effort to locate the sites of the Raleigh colonies in the park, and any results discovered by CART would provide valuable information — even if the wished-for colonial remnants do not materialize. Relatedly, Klingelhofer said the First Colony Foundation also has plans to continue its search, on the south end of Roanoke Island, as part of its ongoing plan here.
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