The Superior Great Lake is bigger than all of the other lakes combined. Lake Superior’s basin was formed over one billion years ago by tectonic forces. Lava escaped around the edges of a large plateau, causing it to collapse and form a basin that solidified over time. This “Superior Basin” was then later filled with water during the glacial periods which filled the basin when the glaciers retreated northwards. The Lake Superior is being expanded over time by rift valleys. I think eventually Lake Superoir will merge with othe Great Lakes. Thus forming one big Great Lake.