Recovering Forgotten Indigenous Landscapes Using Electromagnetic Technology

Although monumental earthworks can be found from southern Canada to Florida and from Wisconsin to Louisiana, Ohio has the largest known collection of these structures in the United States, despite the fact that Ohio has no federally recognized Native American tribes. Their creators have been grouped under a loose term, “Hopewell Culture”, named after the family on whose farmland one of the earliest studied mounds was found. Cultural activities associated with the Hopewells are thought to have ended in the Ohio region around 450 to 400 BCE. Tribes such as the Eastern Shawnee, the Miami Nation, and the Shawnee—who historians believe are the most likely modern descendants of the mound builders—were violently displaced by the European genocide of the native population of the mainland and now live on reservation land in Oklahoma. .

Glenna Wallace, Chief of the Eastern Shawnee Tribe, is one such descendant. When we spoke, Wallace was on his way to Washington, DC, to meet with President Joe Biden for the White House Tribal Nations Summit. These annual events were first held in 2009 by President Barack Obama, but were discontinued under the Trump administration. Wallace had only recently returned from southern Ohio, where she had visited sites associated with her tribe’s ancient roots. “The Native American voice hasn’t been very strong in Ohio. The things our people have done there haven’t necessarily been given the best protection that should be possible,” she told me. “People were forced to leave and our mounds were not taken care of.”

Burks and I had traveled about 70 miles southeast of Columbus, along winding, creek-lined roads and rough roads, to reach a small family farm in the Appalachian foothills. The trees around us were crisp with autumn leaves. A herd of cattle passed, their muscular backs framed by distant hills. As Burks completed the 20-minute process of assembling his magnetometer — when complete, it would form a stroller nearly seven feet wide, weighing about 30 pounds — he pointed out that the vast majority of man-made hills and mounds that he spends his time looking for were physically dismantled a long time ago. In only a few cases were these earthworks first excavated or surveyed; instead, they were simply plowed; bulldozed to build roads, houses and malls; or, in one infamous case, incorporated into the landscaping of a local golf course.

Archaeologists believe these earthworks functioned as religious gathering places, tombs for culturally significant clans, and annual calendars, perhaps all at once.

Until recently, it seemed that much of the continent’s pre-European archaeological heritage had been wiped out, uprooted and lost for good. “People see the plowing and think it completely destroyed the archaeological record here,” Burks said, “but it’s still there.” Traces remain: electromagnetic remnants in the ground that can be detected using specialized surveying equipment. Here in this same pasture, he added, there were once at least three circular paddocks. Our goal that morning was to find them.

Magnetometry, Burks’ specialty, is able to record even tiny variations in the strength and orientation of magnetic fields. When pushed across the landscape, a magnetometer can detect where those fields in the ground below have changed, potentially indicating the presence of an object or structure like old walls, metal tools, or filled pits. which could be graves. Magnetometry is also extremely effective in finding hearths or campfires, the heat of which can permanently alter the magnetism of the ground, leaving behind a clearly detectable signature. This means that even seemingly empty pastures — or, of course, community golf courses and suburban backyards — may still contain magnetic evidence of ancient settlements, invisible to the naked eye.

In such a context, knowing where to start digitization is the first obstacle. Luckily for archaeologists and tribal historians, Ephraim George Squier and Edwin Hamilton Davis, a two-man team working in the mid-19th century, mapped as many earthworks as they could find, motivated to learn more about these man-made landforms. before they are destroyed or permanently forgotten. Explaining the rationale for their project, the authors wrote that the earthworks had received only passing descriptions in the notebooks of other travelers and, they believed, “should be studied more carefully and minutely, and above all, more systematically”. This, they hoped, was their way of “shed some light on the great archaeological questions related to the early history of the American continent”.