Great Lakes

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Great Lakes,

group of freshwater lakes lying along the Great Rift ValleyGreat Rift Valley,
geological fault system of SW Asia and E Africa. It extends c.3,000 mi (4,830 km) from N Syria to central Mozambique. The northernmost extension runs S through Syria and Lebanon, the Jordan valley, the Dead Sea, and the Gulf of Aqaba.
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, E Africa, including Lakes VictoriaVictoria, Lake,
or Victoria Nyanza
, largest lake of Africa and the world's second largest freshwater lake, c.26,830 sq mi (69,490 sq km), E central Africa, on the Uganda-Tanzania-Kenya border. Lake Victoria (c.255 mi/410 km long and c.
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, TanganyikaTanganyika, Lake,
second largest lake of Africa, c.12,700 sq mi (32,890 sq km), E central Africa on the borders of Tanzania, Congo (Kinshasa), Zambia, and Burundi. It is c.420 mi (680 km) long and up to 45 mi (72 km) wide. The lake lies in the Great Rift Valley (alt.
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, NyasaNyasa, Lake
, or Lake Malawi
, Port. Niassa, c.11,600 sq mi (30,040 sq km), c.360 mi (580 km) long and from 15 to 50 mi (24–80 km) wide, E central Africa, in the Great Rift Valley.
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, TurkanaTurkana, Lake,
c.2,500 sq mi (6,475 sq km), NW Kenya and SW Ethiopia, E Africa, in the Great Rift Valley; alt. 1,230 ft (375 m). Surrounded by desolate, volcanic mountains, the 170-mi-long (274-km) alkaline lake is the focus of interior drainage and has no outlet; it is becoming
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, AlbertAlbert, Lake,
or Albert Nyanza
, 2,064 sq mi (5,346 sq km), on the Congo (Kinshasa)–Uganda border, E central Africa. The lake is c.100 mi (160 km) long and c.19 mi (30 km) wide, with a maximum depth of 168 ft (51 m).
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, KivuKivu,
lake, 1,042 sq mi (2,699 sq km), 55 mi (89 km) long, on the Congo-Rwanda border, E central Africa; highest lake in Africa (4,788 ft/1,459 m). It is drained by the Ruzizi River, which flows S into Lake Tanganyika.
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, and EdwardEdward, Lake,
or Edward Nyanza
830 sq mi (2,150 sq km), in the Great Rift Valley, central Africa, on the Congo-Uganda border. It lies at an altitude of c.3,000 ft (910 m), is c.50 mi (80 km) long, and has a maximum width of c.30 mi (48 km).
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. Lakes Victoria, Albert, and Edward empty into the White NileWhite Nile,
river, one of the chief tributaries of the Nile, E Africa. The name is sometimes used for the 600 mi (970 km) long section of the river known as the Bahr el Abiad that extends upstream from Khartoum to the junction of the Bahr el Jebel and the Bahr el Ghazal at Lake
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, Tanganyika and Kivu empty into the CongoCongo
or Zaïre
, great river of equatorial Africa, c.2,720 mi (4,380 km) long, formed by the waters of the Lualaba River and its tributary, the Luvua River, and flowing generally N and W through Congo (Kinshasa) to the Atlantic Ocean.
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 River system, and Nyasa drain through the ShireShire
or Shiré
, river, c.250 mi (400 km) long, flowing from the southern end of Lake Nyasa, Malawi, SE Africa, to the Zambezi River in central Mozambique. It is navigable to Nsanje. The upper Shire has been developed for irrigation and power production.
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 River into the ZambeziZambezi
, river, c.1,700 mi (2,740 km) long, rising in NW Zambia, S central Africa, and flowing in an S-shaped course generally E through E Angola, along the Zambia-Zimbabwe border, and through central Mozambique to the Mozambique Channel of the Indian Ocean, near Chinde.
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. Lake Turkana has no outlet. The Great Lakes region is generally considered to include the nations of Burundi and Rwanda, NE Congo (Kinshasa), Uganda, and NW Kenya and Tanzania. The Economic Community of the Great Lakes Countries, also known as the Economic Community for the Great Lakes Region, was established in 1976 by Burundi, Congo (Kinshasa), and Rwanda but collapsed in the 1990s amid civil war and international strife. The organization was revived in 2007 by its former members.

Great Lakes,

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 SuperiorSuperior, Lake,
largest freshwater lake in the world, 31,820 sq mi (82,414 sq km), 350 mi (563 km) long and 160 mi (257 km) at its greatest width, bordered on the W by NE Minnesota, on the N and E by Ontario, Canada, and on the S by NW Michigan and NW Wisconsin; largest,
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, Lake MichiganMichigan, Lake,
22,178 sq mi (57,441 sq km), 307 mi (494 km) long and 30 to 120 mi (48–193 km) wide, bordered by Mich., Ind., Ill., and Wis.; third largest of the Great Lakes and the only one entirely within the United States.
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, Lake HuronHuron, Lake
, 23,010 sq mi (59,596 sq km), 206 mi (332 km) long and 183 mi (295 km) at its greatest width, between Ont., Canada, and Mich.; second largest of the Great Lakes. It has a surface elevation of 580 ft (177 m) above sea level and a maximum depth of 750 ft (229 m).
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, Lake ErieErie, Lake,
9,940 sq mi (25,745 sq km), 241 mi (388 km) long and from 30 to 57 mi (48–92 km) wide, bordered on the N by S Ont., Canada, on the E by W N.Y., on the S by NW Pa. and N Ohio, and on the W by SE Mich. and NW Ohio.; fourth largest of the Great Lakes.
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, and Lake OntarioOntario, Lake,
7,540 sq mi (19,529 sq km), 193 mi (311 km) long and 53 mi (85 km) at its greatest width, between SE Ont., Canada, and NW N.Y.; smallest and lowest of the Great Lakes.
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, 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 Superior's 602 ft (183 m) to Lake Ontario's 246 ft (75 m); the greatest sudden drop occurs at Niagara Falls (167 ft/51 m) between lakes Erie and Ontario; the water levels fluctuate over the months and years due to climatic changes. 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 BruléBrulé, Étienne
, c.1592–1632, French explorer in North America. He arrived (1608) in the New World with Samuel de Champlain, who sent him (1610) into the wilderness to learn about Native Americans and the land. He lived with the Huron and accompanied (c.
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 visited Lake Huron c.1612. In 1614, Brulé and French explorer Samuel de ChamplainChamplain, Samuel de
, 1567–1635, French explorer, the chief founder of New France.

After serving in France under Henry of Navarre (King Henry IV) in the religious wars, Champlain was given command of a Spanish fleet sailing to the West Indies, Mexico, and the
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 explored Lake Huron and Lake Ontario. In 1679, the French explorer La SalleLa Salle, Robert Cavelier, sieur de
, 1643–87, French explorer in North America, one of the most celebrated explorers and builders of New France.

He entered a Jesuit novitiate as a boy but later left the religious life.
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 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 CanalErie Canal,
artificial waterway, c.360 mi (580 km) long; connecting New York City with the Great Lakes via the Hudson River. Locks were built to overcome the 571-ft (174-m) difference between the level of the river and that of Lake Erie.
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 in 1825 accelerated the development of commerce on the Great Lakes.

The opening of the St. Lawrence SeawaySaint Lawrence Seaway,
international waterway, 2,342 mi (3,769 km) long, consisting of a system of canals, dams, and locks in the St. Lawrence River and connecting channels between the Great Lakes; opened 1959.
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 in 1959 made the Great Lakes a truly international water body. The Illinois WaterwayIllinois Waterway,
336 mi (541 km) long, linking Lake Michigan with the Mississippi River, N Ill.; an important part of the waterway connecting the Great Lakes with the Gulf of Mexico.
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 connects the lakes with the Mississippi River and the Gulf of Mexico; the New York State Canal SystemNew York State Canal System,
waterway system, 524 mi (843 km) long, traversing New York state and connecting the Great Lakes with the Finger Lakes, the Hudson River, and Lake Champlain.
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 (including 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 lakes' 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.

Bibliography

See J. Rousmaniere, ed., The Enduring Great Lakes (1979); C. E. Feltner and J. B. Feltner, Great Lakes Maritime History (1982); S. L. Flader, ed., The Great Lakes Forest (1983).

Great Lakes

 

a group of large lakes in the eastern part of North America, in the St. Lawrence River basin. They consist of Lakes Superior, Huron, Michigan, Erie, and Ontario. Lake Michigan is entirely within the USA, and the border between the USA and Canada runs through the rest of the lakes and the short rivers that connect them. About one-third of the water area belongs to Canada.

Table 1. Great Lakes
 Altitude above
sea level (m
)
Area
(thousand sq km
)
Greatest depth
(m
)
Superior ...............18382.4393
Huron ...............17759.6208
Michigan ...............17758.0281
Erie ...............17425.764
Ontario ...............7519.5236

The shore line (with islands) is about 18,000 km long. The Great Lakes are the largest accumulation of fresh water on earth. Their area is 245,200 sq km, and the area of their basin (including the lakes themselves) is 768,000 sq km. Their volume of water is 22,725 cubic km. Four lakes have depths greater than 200 m, and only in Lake Erie is the greatest depth 64 m. The largest and deepest of the lakes is Lake Superior, and the smallest is Lake Ontario. The Great Lakes are situated on different levels, but the height difference of the first four (see Table 1) does not exceed 9 m in all (183 m, Lake Superior and 174 m, Lake Erie), and only the lowest lake, Ontario, is situated almost 100 m below Lake Erie. The lakes are united by short, large-volume rivers with many rapids; the Ste. Marie River unites Lake Superior and Lake Huron (112 km long); the St. Clair River (43 km), Lake St. Clair (1,275 sq km in area), and the Detroit River (51 km) unite Lake Huron and Lake Erie; and the Niagara River (54 km), which forms Niagara Falls (c. 50 m high), unites Lake Erie and Lake Ontario. Lakes Huron and Michigan, which are at the same altitude, are joined by the Straits of Mackinac, which are about 3 km wide. Several hundred small rivers fall into the Great Lakes, which drain through the St. Lawrence River and flow from Lake Ontario into the Atlantic Ocean. The average outflow of water at its source is 6,637 cu m per sec.

The basins of Lake Superior and the northern part of Lake Huron were formed from the crystalline rocks of the southern part of the Canadian shield, whereas those of the remaining lakes were formed from a mass of limestones, dolomite, and sandstones of the Paleozoic North American platform. These basins formed as a result of tectonic movement and pre-Ice Age and Ice Age river and glacial erosion. The origin of the Great Lakes water mass is related to the melting of the glacial cover, the recession of which formed in the area a series of large lakes, which changed their outlines many times. The northern part of the shore line is broken, and the islands and shores (to 400 m high) are rocky, precipitous, and very picturesque. This is particularly true of the shores of Lake Superior and the northern parts of Lake Huron. The shores of the southern and southeastern parts of the lakes are primarily low, clayey, and sandy.

Fluctuations of the level of the Great Lakes is artificially regulated for purposes of navigation, power generation, and so on. The amplitude of seasonal fluctuation is 30-60 cm; the highest levels come in the summer and the lowest in winter. Short-term fluctuations in the water level caused by strong winds and seiches reach 3-4 m. The height of the tides is 3-4 cm (Lakes Superior and Michigan). The lakes freeze only in the shore zone (from December to March or April). As a result of frequent fall and winter storms the central parts of the lakes do not remain completely frozen over. The duration of navigability is eight to nine months a year.

In the lakes are found 173 species of fish, mainly of the carp, perch, and salmon families. Whitefish and trout are of economic significance.

In the south and southeast heavily settled industrial regions of the USA and Canada border on the Great Lakes; there are agricultural and raw-material regions in the north and west. Some of the largest cities of the USA are situated on the Great Lakes; Chicago and Milwaukee are on Lake Michigan; Buffalo and Cleveland are on Lake Erie; the center of the auto industry, Detroit, is on the river of the same name near its entrance into Lake Erie; and the second largest city in Canada, Toronto, is on Lake Ontario. The Great Lakes are joined to the Mississippi River basin by a system of navigable canals that begin near Chicago on Lake Michigan and to the Hudson River (on which New York is located) by a canal beginning in Lake Erie near Buffalo.

The Great Lakes form a deepwater internal shipping route 1,873 km long (from the largest port, Duluth, on Lake Superior to the source of the St. Lawrence River), by means of locks that bypass rapids on the Ste. Marie River (the Sault Ste. Marie Canal) and Niagara Falls on the Niagara river (Welland canal).

As a result of the completion in 1959 of the reconstruction of the canals built to avoid the rapids of the St. Lawrence River, a continuous water route from the Great Lakes to the Atlantic Ocean was created. Its length is about 3,000 km, and its depth is not less than 8 m, thus making it available to large oceangoing vessels. The main flow of cargo is from west to east (wheat and iron ore); the primary freight moving from east to west is coal. The annual freight turnover on the Great Lakes is about 200 million tons, of which more than half takes place in Lake Superior. The freight is carried mainly in ships belonging to American companies. The tonnage of the Canadian Merchant Marine on the Great Lakes constitutes only one-fourth of the total lake fleet tonnage.

REFERENCES

Baulig, H. Severnaia Amerika. Moscow, 1948. (Translated from French.)
Kanada: Geograficheskie raiony. Moscow, 1955. (Translated from English.)
The Laurentian Great Lakes of North America. Uppsala, 1968.

O. A. SPENGLER

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