[2] The first stage occupied only the south part of the basin of Lake Huron, including Saginaw Bay.

Its existence is based on evidence of the establishment and erosion of its outlet through the distributaries of the St. Clair River at St. Clair, and on characters of the Niagara River and gorge.

The steps of transition following this are simply physical and logical necessities, made so by the conditions of development from the first stage to the later fully developed Lake Algonquin, which included all three of the upper Great Lake basins.

With water levels dropping, the two basins of Michigan and Huron, separated into individual lakes, entering the Lake Chippewa low phase in the Michigan Basin and the Lake Stanley Low Phase in the Huron Basin.

As the glacial front melted northward, the lake expanded in the Huron basin.