Great Lakes Island, Harsens Island, Manitoulin Island, and the Toronto Islands. As of 2007, four car ferry services cross the Great Lakes, two on Lake Michigan: a steamer from Ludington, Michigan, to Manitowoc, Wisconsin, and a high speed catamaran from Milwaukee to Muskegon, Michigan, one on Lake Erie: a boat from Kingsville, Ontario, or Leamington, Ontario, to Pelee Island, Ontario, then onto Sandusky, Ohio, and one on Lake Huron: the M.S. Chi-Cheemaun runs between Tobermory and South Baymouth, Manitoulin Island, operated by the Owen Sound Transportation Company. An international ferry across Lake Ontario Rochester, New York, to Toronto ran during 2004 and
Great Lakes for Lakes Ontario and Erie were created, along with what would become the Saint Lawrence River. The Great Lakes are estimated to have been formed at the end of the last glacial period (the Wisconsin glaciation ended 10,000 to 12,000 years ago), when the Laurentide Ice Sheet receded. The retreat of the ice sheet left behind a large amount of meltwater (see Lake Algonquin, Lake Chicago, Glacial Lake Iroquois, and Champlain Sea) that filled up the basins that the glaciers had carved, thus creating the Great Lakes as we know them today. Because of the uneven nature of glacier erosion,