Lakes
A lake is a large area of water that is not salty, surrounded by land and not connected to the sea except by rivers or streams.
The Great Lakes are a group of five freshwater lakes, central North America, creating a natural border between the United States and Canada and forming the largest body of freshwater in the world, with a combined surface area of c.95,000 sq mi (246,050 sq km). From west to east they are Lake Superior, Lake Michigan, Lake Huron, Lake Erie, and Lake Ontario, out of which flows the Saint Lawrence River. The distance from Duluth, Minn., at the western end of Lake Superior, to the outlet of Lake Ontario is 1,160 mi (1,867 km). The international boundary passes approximately through the center of all the lakes except Lake Michigan, which lies entirely within the United States.
The Great Lakes were formed approximately at the end of the Pleistocene period, when the glacier-carved lake basins were filled with meltwater from the retreating ice sheet. The lakes are connected to each other by straits, short rivers, and canals. The height above sea level of the lake surfaces varies from Lake Superior¹s 602 ft (183 m) to Lake Ontario¹s 246 ft (75 m); the greatest sudden drop occurs at Niagara Falls (167 ft/51 m) between lakes Erie and Ontario. All the lake bottoms, except that of Lake Erie, extend below sea level.
French traders were the first Europeans to see any of the Great Lakes; Étienne Brulé visited Lake Huron c.1612. In 1614, Brulé and French explorer Samuel de Champlain explored Lake Huron and Lake Ontario. In 1679, French explorer Robert LaSalle sailed from Lake Erie to Lake Michigan. The Great Lakes region, rich in furs, was contested for many years by the French, English, and Americans. The close of the War of 1812 finally ended the struggle for possession of the Great Lakes, and settlement of the region rapidly followed. The opening of the Erie Canal in 1825 accelerated the development of commerce on the Great Lakes.
The opening of the St. Lawrence Seaway in 1959 made the Great Lakes a truly international water body. The Illinois Waterway connects the lakes with the Mississippi River and the Gulf of Mexico; the New York State Barge Canal (the successor of the Erie Canal) joins the Great Lakes with the Hudson River and the Atlantic Ocean. Shipping on the lakes carries large quantities of iron ore and grain, coal, and petroleum, and manufactured articles from April until December, until ice closes most of the ports and winter storms hinder navigation. The large industrial lakefront cities include Toronto, Hamilton, Buffalo, Cleveland, Detroit, Gary, Milwaukee, and Chicago. Large concentrations of population and industry along the lakes¹ shores led to pollution, especially of Lake Erie, but the condition of the lakes has improved since the 1960s. The Great Lakes region, with its national parks and lakeshores, state parks, and many natural and scenic features, has become an important year-round recreation area.
Lake Vanishes Suddenly in Chile National Geographic - April 14, 2008
Shrinking Lake Superior Also Heating Up National Geographic - August 3, 2007 Lake Superior, the world's largest freshwater lake, has been shrinking for years and now it appears to be getting hotter.
Lake disappears suddenly in Chile BBC - June 22, 2007
Mystery of World's Fastest-growing Lakes Solved Live Science - June 27, 2005
In Alaska, thousands of mysterious lakes are all the same shape and have grown steadily for thousands of years, the geological record shows. They are the fastest growing lakes known in the world. Scientists have tried various ideas to explain the steady growth -- the lakes expand up to 15 feet every year -- and the lakes' consistent shape and orientation, but no theory has held up. Now a scientist who has worked previously on puzzles as wide-ranging as the spiral shape of Mars ice caps says he's solved the terrestrial mystery.
Rising water changing Utah's Great Salt Lake CNN - June 11, 2005
The water in the Great Salt Lake has begun rising again after years of drought, changing the landscape and starting to submerge one of Utah's best-known artifacts: an enormous earth sculpture called the Spiral Jetty. The six years of drought had allowed the curious to flock to the lakeside to see the 1,500-foot-long, salt-encrusted spiral that Robert Smithson built in 1970 using backhoes to pile up rock and earth.
For decades before the dry spell, the jetty had largely been just out of sight beneath the surface of the salty water.Thanks to a winter of record snowfall, it's not just the spiral Jetty that is changing. "Change in lake levels can produce significantly more of a change than you'd expect," says Maunsel Pearce, chairman of the Great Salt Lake Alliance, a consortium of conservation groups with interests in the lake. "You really need to see it to believe it."
Sandbars exposed during the drought are now covered with water. Wetlands that had dried into sheets of cracked mud and thin dry grasses are now soggy marshes sprouting thick vegetation. Water also is inching back toward Antelope Island, although boat docks there remain beached. The lake's elevation averages about 4,200 feet above sea level, a level at which water spreads out across about 1,700 square miles, according to data kept since 1875 by the U.S. Geological Survey. But the drought that began in 1999 dropped the surface by about 6 feet, shrinking the lake to just 950 square miles. As of Saturday, it had gone back up a bit less than 4 feet, according to a USGS Web site.
Such fluctuations are part of what makes the lake beautiful, says Lynn de Freitas, executive director of Friends of the Great Salt Lake. Each climate pattern changes the lake and people's perception of it, she said. The Great Salt Lake is a remnant of the ancient Lake Bonneville, which more than 12,000 years ago covered some 20,000 square miles of what is now Idaho, Utah and Nevada.
Although just glimmer of its former self, the Great Salt Lake still is the world's fourth largest "terminal lake," where water flows in but doesn't flow out. Water delivered to the lake by four rivers is lost only through evaporation, which concentrates its mineral content, leaving behind a harsh solution in which only salt-tolerant species of brine shrimp, bacteria and algae can survive. Mineral companies extract selenium and magnesium from the lake bed. Commercial fishermen harvest brine shrimp. Each of those industries and recreational users were affected by the drought and will be again by the rising water, de Freitas notes. Rising water in the north arm of the lake will dilute the salty water where the Spiral Jetty sits and stimulate bacterial growth that turns the water pinkish-red, offering a different vision of the sculpture, de Freitas said. "The drama of the ability to see the jetty, I think now is actually improved," she said. "Now the water and is coming up and lapping at the jetty and even though you're slogging through the water, there's still a vague visible presence. I think people will find it more in keeping with the photographs they've seen."
Astrobiologists Find Fossils of Ancient Life at World's Highest Lake Space.com - October 28, 2002
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