Late Precontact burial mounds in Michigan located near lakes with long maize growing season
“Knee high by the Fourth of July!” - a common Midwestern saying I heard often while growing up in rural Lenawee County, Michigan. The phrase refers to the growing season for corn (maize). The farmers’ folk wisdom holds that corn stalks should be as tall as one’s knee by July 4 to ensure a good harvest in the fall.
Corn infamously requires a longer growing season which can pose a challenge for farmers and gardeners alike in northern states.
A recent study by Meghan Howey, Ph.D. and Michael Palace, Ph.D., both of the University of New Hampshire, indicates that a long growing season was something Michiganders looked for as far back as 800 years ago. The paper, published in PNAS in December, is titled Satellite thermal data applied to landscape archaeology: Mounds in Michigan (1200–1600 CE).
Howey and Palace used data from Landsat 8 Thermal Infrared Sensor available in Google Earth Engine to analyze temperatures at thousands of inland lakes in Michigan’s Lower Peninsula. They then compared that data to a “legacy mound database” that records known archaeological burial mounds from the Late Precontact Period (1200-1600). Unlike the Landsat data, the mound database is not available to the public to prevent looting.
Howey and Palace found an interesting correlation in which lakes with burial mounds located near them were more likely to have longer growing seasons for maize:
Results show lakes with mounds warmed later in the spring, cooled later in the fall, and were more regularly shaped, suggesting Late Precontact communities placed mounds on lakes with specific resource benefits, including extended growing seasons.
Considering the emphasis on longer growing seasons, the authors suggest that “maize may have played a bigger role than previously thought” in the Late Precontact Period.The code developed by the authors for the paper is available in Google Earth Engine.
Who lived in Michigan at the time?
Early According to the Milwaukee Public Museum, the Indigenous peoples of the Lower Peninsula around 1600 included the Potawatomi, Sauk, Mascouten, Fox, Miami and Kickapoo.
Native Americans living in Michigan between 1200 and 1600 made a living by “targeted fishing of seasonal spawns, intensified use of storable wild plant foodstuffs such as acorns, berries, maple syrup, and wild rice, and some level of expansion of maize cultivation,” Howey and Palace explained.
The practice of constructing burial mounds had a deep history in the region by the time of the Late Contact Period. Indigenous mound building cultures existed for millennia in the American Midwest and South. Mound building in southern Ohio stretches back at least to 500 BC with the Adena culture, tipified by sites like the 65-foot-tall Miamisburg Mound just outside of Dayton, Ohio.