Nick you are correct there are large piles of rocks out there and yes they did dump the dredgings from the Detroit River there the rest of dredgings are what we know as Seaway Island and Gull Island. The original name was the Grosspoint dumping ground and dates back to 1874 (that's the original spelling of Grosse Pointe).There's also cars,rolls of steel,spools of cable,doors,windows,boats,tires,bricks etc... I started diving that area 20 yrs ago. We were always amazed at what we would come across. The one thing we never found and we have been told is out there was human remains
. Back in the day when the lake was iced over late in the winter they would take all kinds of things out there and leave it till ice out. They would also do night dumps in the summer when they did not want anyone seeing what they were dumping. That kind of clandestine "dumping" went on for years and i'm told stilll does.