Academics & Research / Summer 2017

Using ground-penetrating radar, anthropology professor explores the world underground

Larry Conyers and students work at a Wheat Ridge graveyard. Photo: Wayne Armstrong

Ten miles inland from the coast of the Connecticut River, the landscape is punctuated by a picturesque horse ranch complete with leafy shade trees, white picket fences and expanses of bright green grass. But DU archaeologist Larry Conyers can show you an entirely different picture of the farm … underground.

Conyers and two graduate students, Maeve Herrick and Jasmine Saxon, used ground-penetrating radar (GPR) technology to find out if an early 17th-century farmstead was once located at the site of the expansive ranch, which is now owned by a local family. The DU team ended up uncovering what may be the first archaeological evidence of cohabitation between early colonists and Native Americans.

“This is arguably the most important historic period archaeological site to be identified in the state of Connecticut,” says Brian Jones, who, as Connecticut state archaeologist, is leading the investigation of the property. “The site documents an especially poorly understood period of colonial history as the first English settlers of the Connecticut River Valley adjusted to a new way of life.”

Conyers, who chairs DU’s anthropology department, is the world’s leading expert on GPR, a technology that uses high-frequency radar pulses to create images of objects and architecture buried underground. GPR is critical to the field of anthropology because it allows scientists to avoid the often irrevocable damage to buried materials frequently associated with excavation. Rather than spend months or years digging in the ground, Conyers can safely use GPR to view what is otherwise hidden to the human eye.

Conyers and the two students determined that the Connecticut horse farm was once a multi-house colonial family settlement from the 1630s. Their research also revealed evidence that Wangunk Indians lived in or near the settlement at the same time as the colonists.

“Very few 17th-century English settlements have been identified in Connecticut, and next to nothing related to 17th-century English settlement had been archaeologically explored,” Jones says. “The presence of Native American material on the site adds to our appreciation of the complex relationship between the English and their native neighbors at this time.”

Archaeologists like Jones and historians around the world regularly ask Conyers to investigate their sites because of his masterful use of GPR technology. He has uncovered medieval Irish farming communities, African mass graves and buried pueblos. He selects projects, in large part, based on what would make good research assignments for his graduate students.

Members of the Connecticut team contacted Conyers when their preliminary site work gave them reason to believe that historically significant artifacts were located at the horse ranch. Locals had long believed the site was a colonial homestead. The property owners knew their ancestors were early settlers, and the family was curious about what might be buried there.

“It was a perfect test site for GPR because the land had been relatively untouched—it’s been used only as a working farm by the same family for centuries,” Conyers says. He accepted the Connecticut invitation, and Herrick and Saxon had their thesis projects.

In close partnership with the owners, state officials and community volunteers, Herrick and Saxon first conducted a large, magnetic, geophysical survey during DU’s spring break in 2016. This guided them to the general area of what turned out to be important buried features. Next, they collected GPR data that revealed exactly where the team should excavate to find artifacts: buried cellars of the earliest houses.

Herrick and Saxon, both of whom came to DU to study GPR under Conyers, used the radar equipment to point to the location where a rare and fully intact Native American pot was discovered. Ultimately, hundreds of pottery fragments were discovered throughout the site.

Curiously, they found the intact pot inside the cellar of a colonial home. Obtaining an intact artifact is particularly important because very few fragile artifacts are found wholly preserved. Finding it in the colonial home creates more questions than answers.

In addition, the graduate students found a possible series of Native American dwellings about 200 feet southwest of the colonialist houses. There is some indication that Native American dwellings may have stood right in the middle of the cluster of colonial houses.

“We just don’t know yet,” says Conyers as to why Native Americans and early colonists may have cohabitated. The DU team has dozens of working hypotheses that must be tested. With the artifacts already discovered providing what Jones calls “tangible proof of the close relationship between the colonials and the neighboring Wangunk people,” the Connecticut team expects to continue working at the site for five more years.

“The most memorable event was when we started to break ground at the site,” Saxon says. “Maeve and I had already run the GPR survey and had calculated the depth to the top of each cellar. When we later excavated, our measurements were exactly on. It was really exciting to take all of the GPR knowledge that we had learned and apply it to a real-life scenario, especially because we were so accurate.”

Conducting GPR research is both taxing and time-intensive. As Conyers notes, “The students must spend time every evening on site, processing and visualizing their data from that day. But the really hard work is done back on campus. It can take up to a week of analysis and processing for every day of collection in the field.”

Independent research by other archaeologists needs to be completed to verify the DU team’s findings. In the meantime, Conyers has asked his students several huge yet basic questions: “What was the pot doing in the cellar? What were the houses doing so close together?” Herrick and Saxon will attempt to answer Conyers’ questions in their theses. They also hope to abate the curiosity of the property’s owners.

Conyers, meanwhile, is delving into other GPR projects around the world. He’s done roughly 400 so far. Recent projects include searches for Neanderthal remains in coastal Portugal; Aborigine graves in Australia; temples and tombs in the Middle East; medieval castles in Ireland; and ancient Roman sites in Croatia. In spring 2017, with DU undergraduate and graduate students in tow, he ventured to a Wheat Ridge graveyard at the request of the Roman Catholic Archdiocese of Denver. Conyers helped officials there discover the location of a woman’s body buried more than 100 years ago. The church is considering making her a saint.

“All GPR projects are great. Every survey is different and a challenge, as the materials in the ground are unknown or only vaguely known,” Conyers says. “As the ground conditions are always different, what is found buried in that ground is always exciting.”


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