GREENSBORO — Ari Lukas looks like he’s doing yard work with the most high-tech mower or lawn-fertilizing device ever made. While it might appear that way, he’s more concerned with what is under the surface than what's growing on it. That’s because the rolling tool that he’s pushing is a ground penetrating radar.
“If you look at this screen, you’ll see this is a profile and there’s a spike, so you know something is under here,” he explains, pointing to the video screen on the handle of the cart he's pushing. The screen shows a slice of ground beneath the cart and in the middle of the slice sits a shadowy image. It’s unclear just what the image is.
Archaeology students and faculty from the University of North Carolina at Greensboro have brought the radar to Guilford Courthouse National Military Park in Greensboro to try to solve a Revolutionary War mystery.
Back on March 15, 1781, British troops fought through three lines of American troops and militiamen in this area. With an army about twice the size of the British troops, the colonials fought a bloody battle, trying to slow the British advance through the South. Ultimately General Nathaniel Greene led his troops to escape on what's known as the retreat road, a road archaeologists are still searching for today.
“It was all happening through thick woods with a lot of heavy smoke and lots of small firefights all over,” explains John Durham, a historian with the National Park Service. “General Greene thought this was good ground because he had three ridge lines to put his troops on, and then he would have a good avenue of escape if he didn’t win the battle.”
The British won, taking the battlefield and the village of Guilford Courthouse. Five hundred British soldiers were killed or wounded while the patriots suffered 300 casualties and retreated. But it was a costly victory because the British lost almost a quarter of their army. That set the stage for their defeat at Yorktown and the end of the Revolution.
The challenge for historians is that, while the facts of the battle and its general location are known, the exact position of where everything happened is not.
“Because we don’t know the exact location of what happened, we’re counting on the archaeology to better our understanding of the locations,” adds Durham. “We need the artifacts to tell more of the story, including just where the courthouse was, because the courthouse is the landmark of the town.”
And that’s where the ground penetrating radar comes into play. A small portion of a field in the military park has been marked off with ribbon. It's outlined in a grid pattern. Lukas rolls the radar cart back and forth across the grid, with a spacing of two to three meters between each pass.
“It’s pretty cool because you don’t know what is under the ground and when you get a hit, your imagination goes wild,” says Lukas, pointing once again at the screen, which shows the mysterious dark object. “It opens up the kid in all of us because you’re wondering what could it be!”
Archaeologists admit the best way to find the retreat road would be to excavate the entire area, however that is both expensive and time consuming. Dr. Roy Stine, an associate professor of geography and archaeology at UNC Greensboro, is leading the radar study. He says using the radar, affectionately called ‘The Baby Buggy,’ before digging is much more efficient.
“It sends a radio wave down into the ground, and so the whole thing ground penetrating radar does is look for a change; and the more change the better,” says Stine, who admits the process isn’t perfect. “It doesn’t show everything, but if this was sand all the way down you would get the same signal all the way down. But if there was a rock wall, it would hit that change, and once it hits that change it sends a signal back and says that’s not what I’ve been going through. So that’s basically what we look for when we’re doing that.”
The signal creates a profile of what is under the radar. That data is taken back to the lab for Stacy Curry, a Ph.D. student, to analyze.
“This is a profile of the ground just beneath the cart and starting at the ground you begin to scroll deeper and deeper,” says Curry, who shows how more and more lines appear as the cursor on the computer screen moves. “As we go deeper and deeper more and more things appear. Those could be objects, or different densities of soils. It all depends, which is why you need to combine the radar data with other research of what was in the area.”
The radar data did indicate a good place to dig a test well. Traditional archaeology revealed a treasure trove of objects from the Colonial period, which were taken to the archaeology lab at UNC Greensboro. The artifacts didn’t reveal the exact location of the retreat road, but the potential location is better understood. More information was also gathered about the battlefield and the town itself.
Archaeologist Dr. Linda Stine, director of the archaeology program Applied Laboratory at UNC Greensboro, says she divides all of the items into function groups, such as kitchen, architecture and battlefield. One of the best-preserved items is a metal brace, which was placed near the barrel of a musket to hold the ramrod in place. Another item recovered appears to be a fishing spear. Together, the hundreds of items indicate that a town and the retreat road were nearby.
“We haven’t found the road yet, but it’s personal items like this ring that bring you closer to the past,” says Dr. Linda Stine, as she scans a table filled with items. “Soldiers wore rings like this and so did regular people.”
“Almost everything we do sheds more light on what happened here and what life was like here,” adds Dr. Roy Stine, as he watches students rolling the radar back and forth across the grid. “It’s important to place this whole landscape in context, not only to preserve it but also to understand it.”