Flashback-Magical World (Part 10)

The majority of lakes on Earth are fresh water, and most lie in the Northern Hemisphere at higher latitudes. Canada, with a deranged drainage system, has an estimated 31,752 lakes larger than 3 square kilometers and an unknown total number of lakes estimated to be at least 2 million. Finland has 187,888 lakes 500 square metres (5,400 sq ft) or larger, of which 56,000 are large (10,000 square metres (110,000 sq ft).

Most lakes have at least one natural outflow in the form of a river or stream, which maintain a lake's average level by allowing the drainage of excess water. Some lakes do not have a natural outflow and lose water solely by evaporation or underground seepage or both. They are termed endorheic lakes.

Evidence of extraterrestrial lakes exists as indicated by the Cassini Probe observing the moon Titan. NASA had announced that evidence of lakes filled with methane existed on the moon Titan of the planet Saturn.

There are tectonic lakes- lakes formed by the deformation and resulting lateral and vertical movements of the Earth's crust.

Volcanic lakes /crater lakes-lakes that occupy craters and maars or larger basins, e.g. calderas, created by volcanic activity. Crater lakes are formed in volcanic craters and calderas, which fill up with precipitation more rapidly than they empty via either evaporation, groundwater discharge, or combination of both.

Glacial lakes-lakes created by the direct action of glaciers and continental ice sheets.

Fluvial lakes- lakes produced by running water.

Oxbow lakes-a crescent-shaped lake called an oxbow lake due to the distinctive curved shape. They can form in river valleys as a result of meandering of the river.

Fluviatile dams-These form where sediment from a tributary blocks the main river.

Lateral lakes-These form where sediment from the main river blocks a tributary, usually in the form of a levee.

Solution lakes also called a karst lake- lake occupying a basin formed by surface dissolution of bedrock. In areas underlain by soluble bedrock, its solution by precipitation and percolating water commonly produce cavities. These cavities frequently collapse to form sinkholes that form part of the local karst topography.

Landslide lakes-lakes created by the blockage of a valley by either mudflows, rockslides. Such lakes are common in mountainous regions

Aeolian lakes- lakes produced by wind action. They are found mainly in arid environments

Shoreline lakes- lakes created by blockage of estuaries or by the uneven accretion of beach ridges by longshore and other currents.

Organic lakes- lakes created by the actions of plants and animals.

Peat lakes- are a form of organic lake.

Anthropogenic lakes-artificially created lakes formed by human activity

Meteorite (extraterrestrial impact/ crater) lakes- which have been created by catastrophic extraterrestrial impacts by meteorites or asteroids.

An acid lake is a lake that has a pH is below neutral (<6.5).

A salt lake, which also known as a brine lake, is an inland body of water situated in an arid or semiarid region, having no outlet to the sea, and containing a high concentration of dissolved salts (principally sodium chloride). Examples include the Great Salt Lake in Utah and the Dead Sea situated between Israel, Jordan and West Bank.

Natural lakes provide a microcosm of living and nonliving elements that are relatively independent of their surrounding environment. Therefore, lake organisms can often be studied in isolation from the lake's surroundings.

Lakes that disappear

The lake may be infilled with deposited sediment and gradually become a wetland such as a swamp or a 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 resulting in a dynamic equilibrium between marsh and lake. This is significant since wildfire has been largely suppressed in the developed world over the past century. This has artificially converted many shallow lakes into emergent marshes. 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 some animals. 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, ephemeral lakes, or seasonal lakes.

Extraterrestrial lakes

One of Saturn's satellite is Titan. The north polar of Titian has hydrocarbon seas and lakes as seen in a false-color Cassini synthetic aperture radar mosaic. Only one world other than Earth is known to harbor large lakes, Saturn's largest moon, Titan. Photographs and spectroscopic analysis by the Cassini–Huygens spacecraft show liquid ethane on the surface, which is thought to be mixed with liquid methane. The largest Titanean lake, Kraken Mare at 400,000 km, is three times the size of any lake on Earth, and even the second, Ligeia Mare, is estimated to be slightly larger than Earth's Lake Michigan–Huron.

Jupiter's large moon 'Lo' is volcanically active, as result sulfur deposits have accumulated on the surface. Some photographs taken during the Galileo mission appear to show lakes of liquid sulfur in a volcanic caldera, though these are more analogous to the lake of lava than of water on Earth.

The planet Mars has only one confirmed lake which is underground and near the south pole. The surface of Mars is too cold with little atmospheric pressure to permit permanent surface water. Geologic evidence confirms that ancient lakes once formed on the surface. It is also possible that volcanic activity on Mars will occasionally melt subsurface ice, creating large temporary lakes. This water would quickly freeze and then sublimate, unless insulated in some manner, such as by a coating of volcanic ash.

There are dark basaltic plains on the Moon, similar to lunar maria but smaller, that are called Lacus because they were thought by early astronomers to be lakes of water.