Coral
Building corals live only in the tropics waters, they may be many miles wide and they also form an island.
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Gulf Stream
Protection of natural resources
Continents
Most Viewed in Geography
Himalayas
Type of clouds
Geography info: Coast, cliffs faces and Erosion
Lake Superior is the largest of the North American Great Lakes.
The Great Lakes
Great Lakes are the largest group of freshwater lakes in the world. Of all inland waters, only the salt-water Caspian Sea is bigger. The five lakes, in order of area, are Lake Superior, Lake Huron, Lake Michigan, Lake Erie and Lake Ontario. Lake Michigan is completely within the United States, but the other four lakes form part of the border with Canada. The levels and areas of the Great Lakes vary slightly, but their combined area is about 95,000 square miles, of which 34,000 are in Canada. The greatest depth is 1,333 feet in Lake Superior.
The Great Lakes drain an area about three times their own size. Water flows from one to another through waterways and locks. Lake Superior is the highest lake, being 600 feet above sea level. Lakes Huron, Michigan and Erie are slightly lower, but Lake Ontario is much lower 245 feet above sea level. Niagara Falls is situated between Lakes Erie and Ontario.
The Great Lakes originally emptied into only the Atlantic Ocean via the St Lawrence River, but now some water also flows south from Lake Michigan through rivers and canals to the Gulf of Mexico. A canal also connects Lakes Erie and Ontario to the Hudson River. Hydroelectric power stations at Niagara Falls and along the St Lawrence Seaway use the water to produce much electricity.
The Great Lakes are very important in the commerce of North America. Great ports and cities, including Chicago, Milwaukee, Buffalo, Cleveland, Duluth, Detroit and Toronto, line their shores. Ships carry iron ore and grain from Lake Superior to Lakes Erie and Michigan, and coal back from Lake Erie to Lakes Michigan and 'Superior. The Great Lakes form a continuous east-west waterway about 1,160 miles long. The westernmost port is Duluth, Minnesota, on Lake Superior. From the eastern end of Lake Ontario, the St Lawrence River flows into the Atlantic.
Sailing on the lakes can be rough in windy weather and sturdy boats must be used. Special barge-like vessels that lie low in the water carry large cargoes. Parts of the lakes freeze over during the winter, but ice-breakers keep the main shipping routes open. Many resorts lie around the shores of the Great Lakes. The most popular resort is Niagara Falls, where water from Lake Erie descends 200 feet to Lake Ontario.
The lakes were formed about 18,000 years ago as glaciers receded at the end of the Ice Age. French explorers claimed the region in the 1600's, and the division of the lakes between the United States and Canada was settled by the War of 1812.
