Research Project: Geophysical Exploration of Prehistoric Northeast Iowa Mounds

Marshall Stay ’17, Anthropology and Classics
Colin Betts, Professor of Anthropology

“Seeing” Beneath the Ground

The goal of this project was to discover potential construction techniques of linear burial mounds in northeast Iowa. “We studied multiple sites using a piece of equipment called a gradiometer,” Stay says. “This instrument allows us to ‘see’ beneath the ground without having to dig or use other intrusive archaeological methods. The gradiometer is helpful to us since burial mounds are protected as cultural heritage sites and excavations aren’t allowed.”

Stay and Betts walked the device along the mound’s grids, used it to upload the data into a software program, and created a gradient map. “The map helps us analyze the subsurface structure of the mound and decide how it was made and where other features might exist,” Stay says.

Difficult Conditions and Reporting the Results

Betts felt the most challenging element of the project was the research environment. “We couldn't survey one of the sites because it was too overgrown with brush/brambles,” he says. “It was also difficult to hike our equipment into the sites we were surveying.”  

Stay, on the other hand, felt most challenged by reporting their results. “I’ve never been involved in a write-up like this before and it required a lot more of my time then I thought it would. There were a lot of late nights!”

Learning About the Mounds

Betts thought it was most interesting to see into the enclosure site and determine how the soil had been moved around to form it. “We could delineate both the areas where the topsoil had been removed and areas (not visible on the surface) where topsoil from other locations had been added,” he says. “It also revealed the parts within the enclosure where people had likely modified the earth. This gave us some insights into the religious/ritual use of the site.”

Stay was intrigued by how they were able to identify highly magnetic subsurface features, or "hot spots," inside the mound. “We believe there is some sort of internal structure or feature at these spots in the mounds that give off a distinct magnetic signature,” Stay says. “These could include rock piles, hearths, or even burials.”