“Forty feet below the surface of Lake Michigan in Grand Traverse Bay, a mysterious pattern of stones can be seen rising from an otherwise sandy half-mile of lake floor. Likely the stones are a natural feature. But the possibility they are not has piqued the interest of archeologists, native tribes and state officials since underwater archeologist Mark Holley found the site in 2007 during a survey of the lake bottom.

The site recently has become something of an Internet sensation, thanks to a blogger who noticed an archeological paper on the topic and described the stones as “underwater Stonehenge.” Though the stones could signal an ancient shoreline or a glacial formation, their striking geometric alignment raises the possibility of human involvement. The submerged site was tundra when humans of the hunter-gatherer era roamed it 6,000 to 9,000 years ago. Could the stones have come from a massive fishing weir laid across a long-gone river? Could they mark a ceremonial site? Adding to the intrigue, one dishwasher-size rock seems to bear an etching of a mastodon.”

(via The Chicago Tribune)