Artificial Lake "Arizona"Origin Of Lakes
There are a number of natural processes that can form lakes. A recent tectonic uplift of a mountain range can create bowl-shaped depressions that accumulate water and form lakes. The advance and retreat of glaciers can scrape depressions in the surface where water accumulates; such lakes are common in Scandinavia, Patagonia, Siberia, and Canada. The most notables examples are probably the Great Lakes of North America.
Lakes can also form by means of landslides or by glacial blockages. An example of the latter occurred during the last ice age in the U.S. state of Washington, when a huge lake formed behind a glacial flow; when the ice retreated, the result was an immense flood that created the Dry Falls at Sun Lakes, Washington.
Salt lakes (also called saline lakes) can form where there is no natural outlet or where the water evaporates rapidly and the drainage surface of the water table has a higher-than-normal salt content. Examples of salt lakes include Great Salt Lake, the Caspian Sea, the Aral Sea, and the Dead Sea.
Small, crescent-shaped lakes called oxbow lakes can form in river valleys as a result of meandering. The slow-moving river forms a sinuous shape as the outer side of bends are eroded away more rapidly than the inner side. Eventually a horseshoe bend is formed and the river cuts through the narrow neck. This new passage then forms the main passage for the river and the ends of the bend become silted up, thus forming a bow-shaped lake.
Crater lakes are formed in volcanic calderas which fill up with precipitation more rapidly than they empty via evaporation. An example is Crater Lake in Oregon, are located within the calderas of Mount Mazama. The caldera was created in a massive volcanic eruption that led to the subsidence of Mount Mazama around 4860 BC.
Some lakes, such as Lake Jackson in Florida, USA, come into existence as a result of sinkhole activity.
Lake Vostok is a subglacial lake in Antarctica, possibly the largest in the world. The pressure from the ice atop it and its internal chemical composition mean that if the lake were drilled into a fissure could result that would spray somewhat like a geyser.
Most lakes are geologically young and shrinking since the natural results of erosion will tend to wear away the sides and fill the basin. Exceptions are those such as Lake Baikal and Lake Tanganyika that lie along continental rift zones and are created by the crust's subsidence as two plates are pulled apart. These lakes are the oldest and deepest in the world. Lake Baikal, which is 25-30 million years old, is deepening at a faster rate than it is being filled by erosion and may be destined over millions of years to become attached to the global ocean. The Red Sea, for example, is thought to have originated as a rift valley lake.
Types of lakes
Periglacial: Part of the lake's margin is formed by an ice sheet, ice cap, or glacier, the ice having obstructed the natural drainage of the land.
Subglacial: A lake which is permanently covered by ice. They can occur under glaciers, ice caps, or ice sheets. There are many such lakes, but Lake Vostok in Antarctica is by far the largest. They are kept liquid because the overlying ice acts as a thermal insulator retaining energy introduced to its underside by friction, by water percolating through crevasses, by the pressure from the mass of the ice sheet above, or by geothermal heating below.
Glacial lake: a lake with origins in a melted glacier.
Artificial: A lake created by flooding land behind a dam, called an impoundment or reservoir; by deliberate human excavation; or by the flooding of an excavation incident to a mineral-extraction operation such as an open pit mine or quarry. Some of the world's largest lakes are reservoirs. Husain Sagar is a reservoir in India created in 1562.
Endorheic, also called terminal or closed: A lake which has no significant outflow, either through rivers or underground diffusion. Any water within an endorheic basin leaves the system only through evaporation or seepage. These lakes, such as Lake Eyre in central Australia or the Aral Sea in central Asia, are most common in desert locations.
Meromictic: A lake which has layers of water which do not intermix. The deepest layer of water in such a lake does not contain any dissolved oxygen. The layers of sediment at the bottom of a meromictic lake remain relatively undisturbed because there are no living organisms to stir them up.
Fjord lake: A lake in a glacially eroded valley that has been eroded below sea level.
Oxbow: A lake which is formed when a wide meander from a stream or a river is cut off to form a lake. They are called "oxbow" lakes due to the distinctive curved shape that results from this process.
Rift lake: A lake which forms as a result of subsidence along a geological fault in the Earth's tectonic plates. Examples include the Rift Valley lakes of eastern Africa and Lake Baikal in Siberia.
Underground: A lake which is formed under the surface of the Earth's crust. Such a lake may be associated with caves, aquifers, or springs.
Crater: A lake which forms in a volcanic caldera or crater after the volcano has been inactive for some time. Water in thise type of lake may be fresh or highly acidic and may contain various dissolved minerals. Some also have geothermal activity, especially if the volcano is merely dormant rather than extinct.
Lava: A pool of molten lava contained in a volcanic crater or other depression. Lava lakes that have partly or completely solidified are also referred to as lava lakes.
Former: A lake which is no longer in existence. Such lakes include prehistoric lakes and lakes which have permanently dried up through evaporation or human intervention. Owens Lake in California, USA, is an example of a former lake. Former lakes are a common feature of the Basin and Range area of southwestern North America.
Shrunken: Closely related to former lakes, a shrunken lake is one which has drastically decreased in size over geological time. Lake Agassiz, which once covered much of central North America, is a good example of a shrunken lake. Two notable remnants of this lake are Lak Winnipeg and Lake Winnipegosis.
Eolic: A lake which forms in a depression created by the activity of the winds.
A lake may be infilled with deposited sediment and gradually become a wetland such as a swamp or marsh. Large water plants, typically reeds, accelerate this closing process significantly because they partially decompose to form peat soils that fill the shallows. Conversely, peat soils in a marsh can naturally burn and reverse this process to recreate a shallow lake. Turbid lakes and lakes with many plant-eating fish tend to disappear more slowly. A "disappearing" lake (barely noticeable on a human timescale) typically has extensive plant mats at the water's edge. These become a new habitat for other plants, like peat moss when conditions are right, and animals, many of which are very rare. Gradually the lake closes, and young peat may form, forming a fen. In lowland river valleys, where a river can meander, the presence of peat is explained by the infilling of historical oxbow lakes. In the very last stages of succession, trees can grow in, eventually turning the wetland into a forest.
Some lakes can disappear seasonally. These are called intermittent lakes and are typically found in karstic terrain. A prime example of an intermittent lake is Lake Cerknica in Slovenia.
Some lakes can disappear seasonally. These are called intermittent lakes and are typically found in karstic terrain. A prime example of an intermittent lake is Lake Cerknica in Slovenia.
Sometimes a lake will disappear quickly. On 3 June 2005, in Nizhny Novgorod Oblast, Russia, a lake called Lake Beloye vanished in a matter of minutes. News sources reported that government officials theorized that this strange phenomenon may have been caused by a shift in the soil underneath the lake that allowed its water to drain through channels leading to the Oka River.
The presence of ground permafrost is important to the persistence of some lakes. According to research published in the journal Science ("Disappearing Arctic Lakes," June 2005), thawing permafrost may explain the shrinking or disappearance of hundreds of large Arctic lakes across western Siberia. The idea here is that rising air and soil temperatures thaw permafrost, allowing the lakes to drain away into the ground.
Neusiedler See, located in Austria and Hungary, has dried up many times over the millennia. A 2005, it is again rapidly losing water, giving rise to the fear that it will be completely dry by 2010.
Some lakes disappear because of human development factors. The shrinking Aral Sea is described as being "murdered" by the diversion for irrigation of the rivers feeding it.
See also: Prairie Lake
More to be Noted
The largest lake in the world by surface area is the Caspian Sea. With a surface area of 394,299 km² (152,240 mi²), it has a surface area greater than the next six largest lakes combined.
The deepest lake is Lake Baikal in Siberia, with a bottom at 1,637 m (5,371 ft). Its mean depth is also the highest in the world (749 m)It is the world's largest freshwater lake by volume (23,000 km³), and the second longest (about 630 km from tip to tip).
The longest freshwater lake is Lake Tanganyika, with a length of about 660 km (measured along the lake's center line).It is also the second deepest in the world (1,470 m) after lake Baikal.
The world's oldest lake is Lake Baikal, followed by Lake Tanganyika (Tanzania).
The world's highest lake is an unnamed pool on Ojos del Salado at 6,390 metres (20,965 ft)The Lhagba Pool in Tibet at 6,368 m (20,892 ft) comes second.
The world's highest commercially navigable lake is Lake Titicaca in Peru and Bolivia at 3,812 m (12,507 ft). It is also the largest freshwater (and second largest overall) lake in South America.
The world's lowest lake is the Dead Sea, bordering Isral, Jordan, and the West Bank at 418 m (1,371 ft) below sea level. It is also one of the lakes with highest salt concentration.
Lake Superior is the largest freshwater lake by surface area (82,414 km²). It is also the third largest by water volume. However, Lake Huron and Lake Michigan form a single hydrological system with surface area 117,350 km², sometimes designated Lake Michigan-Huron. All these are part of the Great Lakes of North America.
Lake Huron has the longest lake coastline in the world: about 2980 km, excluding the coastline of its many inner islands.
The largest island in a freshwater lake is Manitoulin Island in Lake Huron, with a surface area of 2,766 km². Lake Manitou, located on Manitoulin Island, is the largest lake on an island in a freshwater lake.
The largest lake located on an island is Nettilling Lake on Baffin Island.
The largest lake in the world that drains naturally in two directions is Wollaston Lake.
Lake Toba on the island of Sumatra is located in what is probably the largest resurgent caldera on Earth.
The largest lake located completely within the boundaries of a single city is Lake Wanapitei in the city of Sudbury, Ontario, Canada.Before the current city boundaries came into effect in 2001, this status was held by Lake Ramsey, also in Sudbury.
Lake Enriquillo in Dominican Republic is the only saltwater lake in the world inhabited by crocodiles.
Largest by continent
The largest lakes (surface area) by continent are:
Africa - Lake Victoria, also the second largest freshwater lake on Earth. It is one of the Great Lakes of Africa.
Antarctica - Lake Vostok (subglacial)
Asia - Caspian Sea, also the largest on Earth.
Australia - Lake Eyre
Europe - Lake Ladoga, followed by Lake Onega, both located in northwestern Russia.
North America - Lake Superior
South America - Lake Titicaca, which is also the highest navigable body of water on Earth at 3,821 m above sea level.
Note: Lake Maracaibo can be considered the largest lake in South America. It, however, lies at sea level with a relatively wide opening to sea, so it is better described as a bay.
References
Statistics Finland
http://www.mtstandard.com/articles/2005/06/04/newsnationworld/hjjejdjghhjejd.txt http://www.andes.org.uk/peak-info-6000/ojos-info.htm
http://www.highestlake.com/
External Links
Lakes Database
Lake Classification Systems
UKLakes Database
Midwest Lakes Policy Center
Kashmir lakes
Ponds and Lakes : definitions
Some interesting Islands and Lakes
The Azores Islands, site with abundant information about Lakes in Azores Islands
http://en.wikipedia.org/wiki/Lake"
From Wikipedia, the free encyclopedia
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