The Aetna Earthworks: two old rings on a gravel ridge

About eight centuries ago, people stood on a long gravel ridge in what is now Aetna Township and dug two big circles into the ground. Each is a ring of low earth bank with a ditch around the outside — the western one runs about 157 feet across, the eastern one a bit wider at 174 feet. They sit roughly 2,000 feet apart on the same east-west line, on top of an esker, the kind of winding gravel hill a melting glacier leaves behind. The banks have slumped over the centuries, but you can still trace the shape of them in the woods.

These are the Aetna Earthworks, also called the Missaukee Mounds, and they are far older than the lumber towns around them. Pottery and stone tools dug up here place the builders in the Late Woodland period, somewhere around 1200 AD. The land was handed to the University of Michigan back in 1922, and crews from the university’s museum dug here in the mid-1920s; a Michigan State University team came back in 1965 to look again.

Nobody was buried inside the rings, which puzzled early diggers who expected graves. The leading idea now is that these weren’t tombs but gathering places — somewhere scattered bands of people met to trade, marry, and hold ceremonies, at a moment when corn farming was spreading north and changing how everyone lived. Some scholars read the layout as a retelling of an Anishinaabe origin story, the journey of the bear.

The site went onto the National Register of Historic Places in 1973, one of only two listings in the whole county. It’s quiet, fragile ground — easy to walk past without knowing two civilizations’ worth of years are folded into those grassy banks.