My theory is based on multiple (maybe outdated) books and shows on the region. The lakes STARTED to form about 10K years ago. From what I've read, the earliest known settlements came in and 7000-6000BC, that is a huge amount of time during the formation. In the area where they are pointing at in Lake Huron, the ice covered the area before it could exposed to dry land. If you look at hard evidence, the only shown life on the current bottomlands only go 40ft down. All underwater forests and possible human habitation existed in this zone. It is believed that by 4000BC that the lakes reached their somewhat current form. Even ask the archeologists that this is a THEORY and no hard evidence has been found. There are no tools, huts, or other hard evidence that they were out on the ridge. I have been over the area they claimed shown evidence of man made structures or features that they claim show evidence. What I believe along with a few others is that these bizarre features were creates by retreating glaciers and nothing more.