Yeah, I know that. Growing up in Chicago that point was drilled into our little heads almost daily that our surrounding Geography was carved out by Glaciers (Hills, Moraine Valley, Boulders in Chicago that 'shouldn't be there', etc).
But I was referring specially to the map that shows the Great Lakes disappearing if the sea level dropped 330 ft. That doesn't make sense.
They weren't there...makes sense to me.