Certainly, there are more tests needed to be done to confirm these findings but if this actually turns out to be a man made object then it would place the building of the stones at around 10,000 years ago when the waters of Lake Michigan were much lower due to the glaciation of the area. This time period would also coincide with the extinction of the mastodons in this area. Several pictures of the mastodon are below.
Of course, there is a lot of skepticism with this so called Stonehenge like structure. And the supposed mastodon carving is not too clear in any pictures as of yet. There will need to be many underwater scuba investigations of the area before any of this can be confirmed. One thing the area does have going for it is that there are numerous petroglyph sites and even standing stones. The problem is that these ancient sites are much younger than when the Stonehenge site would have been above water so the questions will remain until better investigations are completed.
So, what is your opinion on these findings? Are they just naturally placed rocks underneath the water and what appears to be a mastodon is just the odd shape of the cracks in the rock? In my opinion, we need more information before a decision can be reached. I am fascinated by these findings though and am utterly intrigued by the numbers of underwater structures we have been finding in the past several decades. It certainly appears that our ancestors had many of their home territories flooded at the end of the last Ice Age and we are now just beginning to find these ancient ruins underneath the waters around the globe. Who knows what awaits us underneath these waters to be discovered.