I wonder how much stuff got lost on ice over the lake and fell to the bottom when it melted.
I have a theory that there was a meteor strike of sufficient size to melt a huge amount of Ice over the Northern Hemisphere above the Canada border, forming a gigantic non-saline lake which eventually broke through an ice dam which held it back from flooding the area we call the great lakes. The flooding would have been unimaginable and froming things like he grand canyon. Then there is the world0wide flood of Noah’s epoch ...