A neat little story about an underwater "structure" discovered in MacDonald Lake, Ontario:
Subsequent dives closely examined the structure for any signs of the use of tools, decorative images or other irregularities, to no avail. The thick layer of silt covering the vertical surfaces suggests that certainly within living memory no human has ever touched the structure. The geologists pointed to a dramatic drought, which gripped Eastern North America between 9000 and 7000 BCE. Conditions were so dry during that time that lake levels in the Great Lakes were up to 50 meters lower and inland lakes, like McDonald Lake, which were still fed by spring melt and summer rain water, were assumed several dozen feet lower than their present water levels.
And why then, at a time when so few humans roamed Ontario, would they pick remote MacDonald Lake for a stone cairn, especially such a large, elaborate one? Here is where the biologist pointed to the conclusion of his 30 years of research: McDonald Lake is home to an ancient, glacial relic lake trout, which had survived several bouts of glaciation and retained unique features, which allowed it to survive, where other fish had perished. From his records, he could also add that McDonald Lake, in prehistoric times was not a lake, but part and north-westerly end-point of an ancient river system which, for millennia, funnelled glacial meltwater south into what was then mighty Lake Agassis.
While many questions remain, it is very intriguing to imagine a small band of early humans, camped on the shores of a remote lake where today modern man camps and catches trout, just as his ancestors did thousands of years ago.
I've written occasioanally on Paleo-Ontario. Here's another post here.