At the end of the last Ice Age, 9,000 years ago, a ridge that now lies below Lake Huron was exposed and became the perfect migration route for vast herds of caribou. While sonar scanning the geological features beneath the lake, American archaeologist John O'Shea of the University of Michigan accidentally clarified part of the lives of the mysterious natives who lived in the Great Lakes region. He found more than 60 stone constructions now underwater that are likely to have been used as hunting blinds. They were not what the team was looking for, and if they had not been submerged by the forming lake, they would have been swept away by the glaciers. O'Shea exclaims, "None of it would have survived if it had been on land. This is the only place you could find this evidence. It's hard to find, but there's no other place you could find it."