Archaeologists uncover massive 1000-year-old Native American fields in Northern Michigan that defy limits of farming

With its cold climate, short growing season, and dense forests, Michigan's Upper Peninsula is known as a challenging place for farming. But a new Dartmouth-led study provides evidence of intensive farming by ancestral Native Americans at the Sixty Islands archaeological site along the Menominee River, making it the most complete ancient agricultural site in the eastern half of the United States.

The site features a raised ridge field system that dates to around the 10th century to 1600, and much of it is still intact today.

The raised fields are comprised of clustered ridged garden beds that range from 4 to 12 inches in height and were used to grow corn, beans, squash, and other plants by ancestors of the Menominee Indian Tribe of Wisconsin.

The findings are published in Science.

"The scale of this agricultural system by ancestral Menominee communities is 10 times larger than what was previously estimated," says lead author Madeleine McLeester, an assistant professor of anthropology at Dartmouth. “That forces us to reconsider a number of preconceived ideas we have about agriculture not only in the region, but globally.”

The researchers surveyed approximately 330 acres. However, they have yet to map the entire site because it extends beyond the edge of where they surveyed. They estimate that they surveyed approximately 40% percent of the site. 

"When you look at the scale of farming, this would require the kind of labor organization that is typically associated with a much larger, state-level hierarchical society," says McLeester. "Yet, everything we know about this area suggests smaller egalitarian societies lived in this region but in fact, this may have been a rather large settlement."

The site is part of Anaem Omot, which stands for the "Dog's Belly" in Menominee. Anaem Omot is a cluster of significant ancestral Menominee archaeological sites that includes several burial mounds and a village that were excavated from the 1950s through the 1970s. It was initially mapped in the 1990s by Marla Buckmaster, an archaeologist at Northern Michigan University, and excavated by Jan Brashler, an archaeologist at Grand Valley State University, who found and radiocarbon dated a corn cupule (the cup-shaped structure on the cob that holds a kernel in place) during excavations. Given the site's cultural significance with its burial mounds, dance rings, and agricultural ridges, it is listed on the U.S. National Register of Historic Places.

Building on earlier work and upon the request of the Menominee tribal authorities, archaeologists from Dartmouth were invited to survey and document the area using new technologies that were previously unavailable. Through this partnership, the team collaborated with David Grignon, tribal historic preservation officer for the Menominee Indian Tribe of Wisconsin and the late David Overstreet, a consulting archaeologist for the College of the Menominee Nation.

In May 2023, after the snow had melted but before the leaves were out, the team conducted an innovative, drone-based survey of a 330-acre area using lidar, a remote sensing technology that uses pulses of light from a laser to map objects on the Earth's surface. Lidar provides a dataset that's like a giant cloud of points with the locations of the trees and rocks, which can be filtered out to see the ground. 

"Lidar is a really powerful tool in any kind of forested or heavily vegetated region where the archaeology is hidden below trees—where no kind of optical imagery can see what's underneath the tree canopy," says senior author Jesse Casana, a professor of anthropology who uses remote sensing technologies regularly in his work.

"Forests are really confounding to archaeology in a lot of ways, so a lot of archaeologists rely on publicly available lidar that has often been obtained from a plane that flies really high. But the resolution of the data is usually too low to see many archaeological features. Drone lidar enables us to collect the same kind of data but at a much higher resolution," says Casana.

The lidar uncovered sets of parallel ridges at the site that create quilt-like patterns stretched across the landscape. The ridges were constructed in various directions, illustrating that their locations may have been determined by individual farmers rather than the direction of the sun or other environmental factors.

The results also revealed: a circular dance ring, a rectangular building foundation that may have been a colonial trading post, two 19th-century logging camps, looted burial mounds, previously unknown burial mounds that were thought to be destroyed in the 1970s, and a burial mound on privately owned land that is currently owned by a mining company.

In August 2023, the team excavated three raised agricultural ridges at various distances from the Menominee River. Through radiocarbon dating of charcoal samples obtained during excavation, they found that the ridges had been rebuilt over a 600-year period, with construction initially around the year 1000, which was during the Late Woodland period.

"All three ridges showed a similar picture in terms of their construction, history and reconstruction," says Casana. "Most field systems have been either lost or destroyed due to intensive land use across most of North America, through farming, including pastures, and the cutting down of trees for urban development."

"Through this research, we get this little window of preservation into pre-Colonial farming in the Upper Peninsula of Michigan," says Casana.

Through the excavations, charcoal, broken pieces of ceramics known as sherds, and artifacts were recovered, suggesting that remains from fires and household refuse were likely used as compost in the fields. The results also showed that wetland soils had been used to enrich the soil. 

"Our work shows that the ancestral Menominee communities were modifying the soil to completely rework the topography in order to plant and harvest corn at the near northern extent of where this crop can grow," says McLeester. "This farming system was a massive undertaking requiring a lot of organization, labor, and know-how to maximize agricultural productivity." 

"We're seeing this kind of landscape alteration in a place where we wouldn't expect it," says McLeester.

"This may be just a little remnant of what must have been a much larger system," says Casana.

The findings have made the researchers consider if perhaps the majority of eastern North America was once covered with agricultural ridges. Findings also challenge existing forest history of the Upper Peninsula, since Sixty Islands would have been deforested during this 600 year period.

The team is continuing their work with the Menominee Indian Tribe of Wisconsin at the Menominee Sixty Islands site with upcoming plans to survey the site and locate ancestral Menominee villages.

McLeester (madeleine.mcleester@dartmouth.edu) and Casana (jesse.j.casana@dartmouth.edu) are available for comment.

Carolin Ferwerda, a research scientist in the Department of Anthropology and Jonathan Alperstein, Guarini, a graduate student in the Ecology, Evolution, Environment & Society program in the Department of Anthropology at Dartmouth also contributed to the study.

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