(published June 30, 2014)
About The Lakes
Earth and sky, woods and fields, the mountain and the sea,
are excellent schoolmasters, and teach some of us
more than we can ever learn from books.
-- John Lubbock
The Great Lakes on the Canada-United States border began to form at the end of the last period of significant glaciation, around 10,000 years ago. As the massive ice sheets retreated, they carved out basins in the land and those basins became filled with meltwater. While each of the five lakes resides in a separate basin, collectively they form a single, naturally interconnected body of fresh water connecting the east-central interior of North America to the Atlantic Ocean. From the interior to the outlet at the Gulf of St. Lawrence, water flows southward from Lake Superior to Lake Huron and Lake Michigan, southward to Lake Erie, then northward to Lake Ontario, and finally northward to the St. Lawrence River. Lake Superior connects to Lake Huron by way of the St. Marys River; Lake Huron connects to Lake Erie by way of the St. Clair River, Lake St. Clair, and the Detroit River; Lake Erie connects to Lake Ontario by way of the Niagara River, including Niagara Falls.
St. Lawrence Watershed
Of the five lakes, Lake Michigan is the only one that is located entirely within the United States; the others form a water border between the United States and Canada. The lakes, which cover an area of about 800 miles from east to west and about 500 miles from north to south, drain a large watershed via many rivers, and are studded with approximately 35,000 islands. The largest among those islands is Manitoulin Island in Lake Huron, the largest island in any inland body of water in the world; second largest is Isle Royale in Lake Superior. Both of these islands are large enough to encompass multiple lakes themselves. The shoreline of the Great Lakes measures approximately 10,500 miles.
Lake Superior, at an elevation of 600 feet, has a surface area of 31,700 square miles with an average depth of 483 feet and a maximum depth of 1,335 feet. Major settlements on the shores of Lake Superior today include Duluth, MN, Marquette, MI, Sault Ste. Marie, MI, Sault Ste. Marie, ON, Superior, WI, and Thunder Bay, ON.
Lake Huron, at an elevation of 577 feet, has a surface area of 23,000 square miles with an average depth of 279 feet and a maximum depth of 748 feet. Major settlements on the shores of Lake Huron today include Alpena, MI, Bay City, MI, Owen Sound, ON, Port Huron, MI, and Sarnia, ON.
Lake Michigan, at an elevation of 577 feet, has a surface area of 22,300 square miles with an average depth of 279 feet and a maximum depth of 925 feet. Major settlements on the shores of Lake Michigan today include Chicago, IL, Gary, IN, Green Bay, WI, Sheboygan, WI, Milwaukee, WI, Kenosha, WI, Racine, WI, Muskegon, MI, and Traverse City, MI.
Lake Erie, at an elevation of 571 feet, has a surface area of 9,910 square miles with an average depth of 62 feet and a maximum depth of 210 feet. Major settlements on the shores of Lake Erie today include Buffalo, NY, Cleveland, OH, Erie, PA, and Toledo, OH.
Lake Ontario, at an elevation of 246 feet, has a surface area of 7,340 square miles with an average depth of 283 feet and a maximum depth of 804 feet. Major settlements on the shores of Lake Ontario today include Hamilton, ON, Kingston, ON, Mississauga, ON, Oshawa, ON, Rochester, NY, and Toronto, ON.
The Great Lakes form the largest group of freshwater lakes on Earth, containing 21% of the world’s surface fresh water. Their total surface area is 94,250 square miles (nearly the same size as the United Kingdom, and larger than the U.S. states of New York, New Jersey, Connecticut, Rhode Island, Massachusetts, Vermont, and New Hampshire combined). Collectively, the Great Lakes contain 5,472 cubic miles of water, or 6.0 x 1015 gallons. That is enough water to cover an area the size of the 48 contiguous U.S. States to a uniform depth of 9.5 feet!
The Great Lakes have a humid continental climate with varying influences caused by air masses from other regions including dry, cold Arctic systems from the North, mild Pacific air masses from the West, and warm, wet tropical systems from the south and the Gulf of Mexico. The lakes themselves have a moderating influence on the local climate and they can also increase precipitation totals and produce lake-effect snowfall. The lake effect is the most well known of the Lakes’ influences on climate. Even late in winter, the Lakes often have no icepack in their middles. The prevailing cold winds from the west pick up the slightly warmer air and moisture from the lake surface and, upon passing over the colder land, produce concentrated, heavy snowfall that occurs in bands or “streamers.”
The same gravitational forces that create tides in the oceans are at work on the Great Lakes. True tides do occur in a twice-daily pattern, but the changes in water height are minimal (less than two inches) and are masked by the greater fluctuation in lake levels produced by wind and barometric pressure changes. The Lakes simply don’t contain enough water for large tides to occur, and are therefore considered to be essentially non-tidal.
In the early and middle 1800s, a number of ambitious construction projects were undertaken in order to facilitate Great Lake navigation. Over the years, many modifications have ensued, yet the original goals and objectives remain the same. Chief among these projects were:
Over the years, efforts have been made to have Lake St. Clair, located between Detroit, MI and Windsor, ON, acknowledged as another “Great Lake.” This would permit it to participate in scientific research projects and associated funding having to do with “The Great Lakes.” Perhaps because of its small size (430 square miles with an average depth of 11 feet and a maximum depth of 27 feet), all such efforts have been defeated. Similar efforts have been made relative to Lake Champlain, located on the border between Vermont and New York. While it is located some distance away from those five lakes currently acknowledged to be “The Great Lakes,” it was formed by the same glacial action, and it also drains into the St. Lawrence River (by way of the Richelieu River). It is, however, also relatively quite small with a surface area of only 490 square miles with an average depth of 64 feet and a maximum depth of 400 feet. In 1988, Lake Champlain briefly became a sixth Great Lake as a result of President Clinton’s signing of Senate Bill 927, but, because of a minor uproar, its Great Lakes status was shortly thereafter revoked.
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