Michigan’s Upper Peninsula is renowned for its challenging climate—cold, with short growing seasons, dense forests, and rugged terrain. These conditions make it a surprising place for large-scale agriculture. Yet, a new study led by Dartmouth College has uncovered compelling evidence that, contrary to what was once believed, the region was home to intensive, sophisticated farming systems cultivated by Native American ancestors. The Sixty Islands archaeological site, situated along the Menominee River, is now recognized as the most complete ancient agricultural site in the eastern United States, shedding light on the surprising agricultural ingenuity of the Menominee people.
This newly discovered site features a complex system of raised garden beds that date back to between the 10th century and the early 1600s, offering a remarkable snapshot of pre-Colonial farming practices. The significance of this site goes far beyond just the crops it supported; it also challenges assumptions about the scale of Native American agricultural systems, suggesting that far more extensive and organized farming took place in the region than previously estimated. Through modern technologies like drone-based lidar surveys, researchers are uncovering a much larger, more complex farming legacy than anyone had expected.
The Surprising Discovery: A Farming System in the Cold North
The discovery at Sixty Islands represents a monumental shift in how we understand Native American agriculture in the northern parts of North America. The site consists of raised fields—distinct ridged garden beds—ranging from four to 12 inches in height, built by the ancestors of the Menominee Tribe. These fields were not just used for gardening but were an integral part of a much larger and sophisticated agricultural system. The primary crops grown here included corn, beans, squash, and other plants that were essential to the Menominee people’s diet and way of life.
Previously, historians and archaeologists believed that farming in Michigan’s Upper Peninsula was limited due to the area’s environmental challenges. The cold temperatures and short growing seasons made it seem highly unlikely that any society could have cultivated large-scale agriculture here. However, the findings from this site prove otherwise.
The scale of the agricultural system found at Sixty Islands is ten times larger than what had been previously estimated. This discovery is a game-changer, forcing us to reconsider what we thought we knew about Native American agriculture not only in Michigan but across North America.
A Large-Scale and Complex Farming System
The raised fields discovered at Sixty Islands are a testament to the scale of the agricultural efforts undertaken by the ancestral Menominee people. The system of clustered ridged garden beds covers an estimated 70% of the lidar survey area, and the researchers have so far surveyed about 40% of the entire site. The ridges are arranged in patterns that suggest individual farmers may have had a hand in determining the layout of the fields, which contrasts with farming systems in more southern regions where sunlight and topography may have dictated field placement.
This is not a small-scale operation. The sheer size of the site, the labor required, and the complexity of the system point toward an organized and extensive agricultural society. According to lead researcher Madeleine McLeester, the scale of the farming system at Sixty Islands would require the type of labor organization typically associated with large, state-level societies. However, based on historical evidence and cultural practices, the Menominee people were thought to have lived in smaller, egalitarian societies.
“Everything we know about this area suggests smaller, egalitarian societies lived in this region,” says McLeester. “But, in fact, this may have been a rather large settlement.”
New Technologies and Discoveries
The breakthrough in understanding the scope of this ancient farming system is largely thanks to the use of cutting-edge technologies like lidar (light detection and ranging). In May 2023, researchers conducted a drone-based lidar survey over a 330-acre area at the site, utilizing the technology to map out the landscape and reveal the presence of these long-hidden agricultural ridges.
Lidar uses laser pulses to scan the ground, allowing researchers to capture detailed topographical data that would be obscured by tree cover and dense vegetation. This method provides much higher resolution than traditional aerial imaging, making it particularly valuable in forested areas like the Upper Peninsula. By filtering out trees and other vegetation, lidar revealed the quilt-like patterns of the raised ridges, which stretch across the landscape in parallel lines.
The lidar also revealed additional features at the site, including a circular dance ring, which may have been used for ceremonial purposes, and several burial mounds—both looted and previously unknown. These features help to further contextualize the Sixty Islands site as a place of significant cultural and spiritual importance to the Menominee people.
Radiocarbon Dating: A 600-Year-Old Agricultural History
Through excavation and radiocarbon dating, the research team determined that the agricultural ridges at Sixty Islands were constructed and rebuilt over a span of 600 years, beginning around the year 1000. The dating of charcoal samples taken from the site confirmed that the raised fields were in use from the Late Woodland period, through the period when Europeans first began to arrive in North America. This time frame places the site firmly within the history of the Menominee people, offering further insight into how they adapted to and thrived in the harsh environment of Michigan’s Upper Peninsula.
Interestingly, the study revealed that the ridges were not just simple earthworks but were a testament to a finely-tuned system of farming. For example, the researchers uncovered evidence that the Menominee people had modified the soil using compost, likely from household refuse and remains from fire pits. They also enriched the soil using wetland materials, demonstrating a deep understanding of how to improve soil quality and maximize agricultural output.
“This farming system was a massive undertaking requiring a lot of organization, labor, and know-how to maximize agricultural productivity,” McLeester notes. “It shows that people in this region were not just surviving but thriving in ways we hadn’t previously thought possible.”
Cultural Significance and Preservation Efforts
The Sixty Islands site, with its raised agricultural beds, burial mounds, and dance rings, holds immense cultural significance for the Menominee Tribe. The site is part of a broader cultural landscape known as Anaem Omot, which translates to “Dog’s Belly” in the Menominee language. Anaem Omot is a cluster of important Menominee archaeological sites, many of which have been excavated since the 1950s.
The Sixty Islands site has long been recognized as a place of cultural heritage, and it is listed on the U.S. National Register of Historic Places. The site’s burial mounds, dance rings, and agricultural ridges are integral to understanding Menominee history and their relationship with the land. In fact, many of the recent excavations and surveys were conducted in partnership with the Menominee Tribe to ensure that the cultural significance of the site is preserved and respected.
“The Menominee Tribal authorities invited us to survey and document the area using technologies like lidar, which were previously unavailable,” says Jesse Casana, senior author of the study. “This collaboration has allowed us to gain a deeper understanding of the site while honoring the Menominee people’s connection to their ancestors and the land.”
Implications for the History of Agriculture in North America
The discovery at Sixty Islands raises intriguing questions about the history of agriculture across eastern North America. Could the entire region have once been covered with agricultural ridges like those found at Sixty Islands? The study’s findings challenge previous assumptions about the historical land use in the Upper Peninsula, suggesting that the region may have been deforested during the 600 years of agricultural activity. The agricultural system at Sixty Islands also raises new questions about the ways in which pre-Colonial societies organized and managed large-scale farming operations.
Through this work, researchers are not only uncovering new details about the ancient past but also rethinking what it means to farm in challenging environments. The discovery of the Sixty Islands site highlights the ingenuity and adaptability of the Menominee people, who transformed the landscape to feed their communities despite environmental obstacles.
Continuing Research and Future Excavations
The research team plans to continue collaborating with the Menominee Tribe in the coming years, with plans to expand their survey of the site and locate additional ancestral villages. They hope to gather more data on the organization of farming systems in the region and their role in sustaining the communities that relied on them.
With its use of innovative technology and its focus on cultural preservation, the study of the Sixty Islands site represents a promising future for archaeological research. By honoring the knowledge and traditions of the Menominee people, this research not only illuminates the past but also empowers the present-day tribe to tell its own story.
Conclusion: A Testament to Resilience and Ingenuity
The discovery of a 1,000-year-old, large-scale agricultural system in Michigan’s Upper Peninsula challenges long-held assumptions about pre-Colonial agriculture in the region. The Sixty Islands archaeological site is a powerful reminder of the ingenuity, resilience, and resourcefulness of Native American communities like the Menominee. By carefully working with modern technology and honoring tribal traditions, this research provides a deeper understanding of how these communities lived, thrived, and adapted to their environment in ways that were far more sophisticated than previously thought.
More information: Madeleine McLeester, Archaeological evidence of intensive Indigenous farming in Michigan’s Upper Peninsula, USA, Science (2025). DOI: 10.1126/science.ads1643. www.science.org/doi/10.1126/science.ads1643