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The Great Lakes of North America are located in the east central portion of North America. They are composed of fresh water (although polluted). One-fifth of the world's surface freshwater can be found in the Great Lakes of North America. The Great Lakes drain into the Atlantic ocean via the St. Lawrence River. These Lakes are each connected by a series of rivers and channels that allow ocean-going vessels to come into the center of the continent. Goods can be shipped from Minnesota to Australia without ever leaving the ship. The Great Lakes along with the St. Lawrence River are referred to as the St. Lawrence Seaway.
The Great Lakes of North America are the most evident geographic feature left behind by the last glacier. In fact, it was only about 15,000 years ago that the glacier retreated and the Great Lakes started to form. They are basically puddles left behind by the glacier. As you know, when you stand on the shoreline of the Great Lakes, you cannot see the other side. They are very large puddles. Over their short life, the Lakes have undergone several fluctuations in size and shape-- they are not finished yet.
H = Lake Huron
O = Lake Ontario
M = Lake Michigan
E = Lake Erie
S = Lake Superior
Port Huron is a control point for three of the Great Lakes. All of the water from Lake Superior, Lake Michigan and Lake Huron flows into the St. Clair River which begins at Port Huron. There is a canal in Chicago that connects Lake Michigan to the Mississippi River system, but the outflow is minimal compared to that of the St. Clair River. Lake Michigan and Lake Huron are essentially one lake (one elevation). As the bed of the St. Clair River erodes, water levels of Lake Huron and Lake Michigan drop. This is a very slow process and we would not be able to view this drop in a single lifetime. But it is just a reminder that the Great Lakes do fluctuate and they will continue to do so. Currently, we are experiencing low water levels in the Great Lakes. This has to do with the amount of precipitation over the last ten years or so-- we are behind.
For a look at the current levels of the Great lakes, click here (optional)
For those of you going into teaching, click here for a tremendous resource on the geography of the Great Lakes Region. (optional)
Other lakes in North America include Great Slave Lake, Great Bear Lake, Lake Winnipeg (all three are in Canada and are glacial in origin), Great Salt Lake and Lake Okeechobee (both in U.S.). None of these five lakes are accessible by ocean-going ships.
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