Electromagnetic radiation and millions of magnetic frequencies are helping TVA, state and tribal archeologists build a nonintrusive, subsurface map of a Native American archeological site that was first recorded in the 1930s.

Located in Jackson County, Alabama, the site was originally recorded before TVA built Guntersville Dam and inundated the reservoir. As part of a large-scale survey to assess the impacts the rising waters would have on the area, some of TVA’s earliest archeologists determined this to be a significant site to be excavated before it went underwater.

“Some excavation was performed in the ’30s, but it actually wasn’t inundated like they thought it would be,” says TVA Senior Archeology Specialist Erin Dunsmore. “Due to the types of excavation performed, their report didn’t offer us as much about the site as we preferred. We didn’t fully know its story. So, the point of this project was to perform a noninvasive geophysical survey that would allow us to build on our knowledge from the original report, but also respect and protect the integrity of the site.”

In partnership with New South Associates Incorporated (NSA) in Greensboro, North Carolina, TVA’s cultural compliance and archeology teams were able to use ground penetrating radar (GPR) and a magnetic gradiometer (MAG) in August of this year to take readings of what’s below the surface.

GPR uses radar pulses, or electromagnetic radiation, to image the subsurface and allows archeologists to detect the depth of buried objects, voids and even architecture. A MAG allows archeologists to take a magnetic reading of a site – revealing differences in the magnetic field of the ground and ultimately registering changes that show the defining features of objects within the subsurface.    

A broader view of the past

“We were able to get a number of geophysical grids that act as three-dimensional maps of the sites underground,” says Sarah Lowry, archeologist and NSA Director of Geophysics. “Some things we looked for were signs of packed dirt or burned earth. Everything around us has a north and a south pole, and when you disturb or heat it up, it changes the alignment of those poles. The MAG can pick up those magnetic signatures and tell us if someone lit a fire, wore a path or dug a ditch. Overall, these readings allowed us to get a broader view beyond the two sample sites from the ’30s and learn more about the site’s function.”  

Due to their ancestral connection to the site, two representatives from the federally recognized Indian tribe known as the Muscogee Nation participated in and assisted with the site survey.

Samples and discoveries   

With the large number of trees in the area, Dunsmore and Lowry says that the three teams were only able to take a sample of the site covering 14 grids. However, with the use of both tools, Dunsmore says that they were able to gather in-depth information for those few samples.  

“Knowing the depth, as well as defining the buried archaeological features — hearths, houses, palisades, pits, etc. — at this site gives us the ability to compare the different data and see what’s a feature and what’s not, saving time in the long run,” she says. “But most importantly, it helps us to preserve sacred places, like mounds or burial grounds.”   

According to Lowry, she and her team are still processing the data, but have confirmed in the original report that this was a habitation site. In addition to the known shell mounds, they have identified a number of pits, possible habitations and living surfaces and now have reason to believe that this was a multicomponent site — meaning it was occupied by a tribe(s) for multiple time periods throughout several thousand years.

“The features we identified hint to the Woodland Period on through to the late Mississippian Period,” Lowry says. “It’s possible that they weren’t living there continuously the whole time, but we don’t really know yet. They probably came back and forth, possibly living there seasonally — especially during the earlier woodland period — or the village size could have expanded or contracted to cause relocations and gaps in the time periods.”

But, while the amount of archaeological features lying beneath the soil is exciting, it’s not really the point of the study says Lowry.  

“It’s not the physical items or quantity of material culture that matter to us,” she says. “The most important thing we’re concerned with is the context, trying to figure out how the tribes lived, what they were doing, how many people lived there, how they communicated with each other and what was important to them. What features are next to or surrounding others will help us tell the site’s story in this way and it’s why we protect sites and don’t allow people to remove artifacts from their location when you find them.”

The NSA team will soon be synthesizing their finds with TVA’s 1930 records and other records from the ’80s. Since the earlier archeologists didn’t have time to go into greater detail than a three-to-four-page write up, Lowry says that they and the tribes will now be able to write a more culturally accurate report that will allow for improved management of the site in the future.   

A new report, leaving room for future generations

Lowry and Dunsmore believe that the team’s practices have left the site nearly untouched for future generations to build on the information they’re gathering.   

“Excavation practices have come a long way since the ’30s; they’re less destructive and more concerned with the interests of the tribes,” Dunsmore says. “A small amount of excavation is still required to know without a shadow of a doubt that the initial observations are correct, but teams like Lowry’s have the expertise to interpret the features within the data and give us an idea of what’s there without ever having to put a shovel in the ground. Then, if we, the tribes or future generations want to go back to study the site further or have questions that are based on this noninvasive preliminary work, excavations can be focused on specific areas to lessen impact and further preserve the site.”

“These noninvasive practices help us to respect the tribes culturally” Lowry agreed. “I don’t want to speak for every single tribe, but working alongside some of them in many projects like this one, I feel that there’s a great desire to learn more about the sites without having to dig them up. They’re nonrenewable and very important--and TVA has been a great partner with us in supporting the tribe’s wishes to practice preservation while working to learn the story behind the artifacts.”

The site remains intact on TVA’s federally protected property — meaning it’s illegal to dig in or remove artifacts — and is safe from any developmental impacts. Without having to take samples to further learn about the site, Dunsmore says that the project was all about good stewardship.  

“We wanted to know more so that we can better understand how to responsibly manage this resource; so that it can be secure for the future,” she says. “Sites like this one are ancestrally important and sacred to the tribes, so TVA’s mission is to ensure that their vulnerabilities are understood and covered in long-term protection.”