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A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any
river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of ...
or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the
ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wor ...
, although, like the much larger oceans, they do form part of the Earth's
water cycle The water cycle, also known as the hydrologic cycle or the hydrological cycle, is a biogeochemical cycle that describes the continuous movement of water on, above and below the surface of the Earth. The mass of water on Earth remains fairly co ...
. Lakes are distinct from
lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into '' coastal lagoons'' (or ''barrier lagoons ...
s, which are generally coastal parts of the ocean. Lakes are typically larger and deeper than
pond A pond is an area filled with water, either natural or artificial, that is smaller than a lake. Defining them to be less than in area, less than deep, and with less than 30% emergent vegetation helps in distinguishing their ecology from tha ...
s, which also lie on land, though there are no official or scientific definitions. Lakes can be contrasted with
river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of ...
s or
stream A stream is a continuous body of surface water flowing within the bed and banks of a channel. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long large streams ...
s, which usually flow in a channel on land. Most lakes are fed and drained by rivers and streams. Natural lakes are generally found in mountainous areas, rift zones, and areas with ongoing
glaciation A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate bet ...
. Other lakes are found in endorheic basins or along the courses of mature rivers, where a river channel has widened into a basin. Some parts of the world have many lakes formed by the chaotic drainage patterns left over from the last ice age. All lakes are temporary over long periods of time, as they will slowly fill in with sediments or spill out of the basin containing them. Many lakes are
artificial Artificiality (the state of being artificial or manmade) is the state of being the product of intentional human manufacture, rather than occurring naturally through processes not involving or requiring human activity. Connotations Artificiality ...
and are constructed for industrial or agricultural use, for hydroelectric power generation or domestic water supply, for aesthetic or recreational purposes, or for other activities.


Etymology, meaning, and usage of "lake"

The word ''lake'' comes from
Middle English Middle English (abbreviated to ME) is a form of the English language that was spoken after the Norman conquest of 1066, until the late 15th century. The English language underwent distinct variations and developments following the Old Englis ...
('lake, pond, waterway'), from
Old English Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the early Middle Ages. It was brought to Great Britain by Anglo-Saxon settlers in the mid-5th ...
('pond, pool, stream'), from
Proto-Germanic Proto-Germanic (abbreviated PGmc; also called Common Germanic) is the reconstructed proto-language of the Germanic branch of the Indo-European languages. Proto-Germanic eventually developed from pre-Proto-Germanic into three Germanic br ...
('pond, ditch, slow moving stream'), from the
Proto-Indo-European Proto-Indo-European (PIE) is the reconstructed common ancestor of the Indo-European language family. Its proposed features have been derived by linguistic reconstruction from documented Indo-European languages. No direct record of Proto-Indo ...
root ('to leak, drain'). Cognates include Dutch ('lake, pond, ditch'),
Middle Low German Middle Low German or Middle Saxon (autonym: ''Sassisch'', i.e. " Saxon", Standard High German: ', Modern Dutch: ') is a developmental stage of Low German. It developed from the Old Saxon language in the Middle Ages and has been documented i ...
('water pooled in a riverbed, puddle') as in: :de:Wolfslake, :de:Butterlake,
German German(s) may refer to: * Germany (of or related to) **Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ge ...
('pool, puddle'), and Icelandic ('slow flowing stream'). Also related are the English words ''leak'' and ''leach''. There is considerable uncertainty about defining the difference between lakes and
pond A pond is an area filled with water, either natural or artificial, that is smaller than a lake. Defining them to be less than in area, less than deep, and with less than 30% emergent vegetation helps in distinguishing their ecology from tha ...
s, and neither term has an internationally accepted definition across scientific disciplines or political boundaries. For example,
limnologist Limnology ( ; from Greek λίμνη, ''limne'', "lake" and λόγος, ''logos'', "knowledge") is the study of inland aquatic ecosystems. The study of limnology includes aspects of the biological, chemical, physical, and geological characteris ...
s have defined lakes as water bodies that are simply a larger version of a pond, which can have wave action on the shoreline or where wind-induced turbulence plays a major role in mixing the water column. None of these definitions completely excludes ponds and all are difficult to measure. For this reason, simple size-based definitions are increasingly used to separate ponds and lakes. Definitions for ''lake'' range in minimum sizes for a body of water from to . Pioneering animal ecologist
Charles Elton Charles Elton may refer to: *Charles Elton (Born, 1993) Professional Rugby Player for Otago Rugby * Charles Isaac Elton (1839–1900), English lawyer, politician, writer and antiquarian * Charles Sutherland Elton (1900–1991), English biologist ...
regarded lakes as waterbodies of or more. The term ''lake'' is also used to describe a feature such as
Lake Eyre Lake Eyre ( ), officially known as Kati Thanda–Lake Eyre, is an endorheic lake in east-central Far North South Australia, some north of Adelaide. The shallow lake is the depocentre of the vast endorheic Lake Eyre basin, and contains ...
, which is a dry basin most of the time but may become filled under seasonal conditions of heavy rainfall. In common usage, many lakes bear names ending with the word ''pond'', and a lesser number of names ending with ''lake'' are, in quasi-technical fact, ponds. One textbook illustrates this point with the following: "In Newfoundland, for example, almost every lake is called a pond, whereas in Wisconsin, almost every pond is called a lake." One
hydrology Hydrology () is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and environmental watershed sustainability. A practitioner of hydrology is call ...
book proposes to define the term "lake" as a body of water with the following five characteristics: # It partially or totally fills one or several basins connected by
strait A strait is an oceanic landform connecting two seas or two other large areas of water. The surface water generally flows at the same elevation on both sides and through the strait in either direction. Most commonly, it is a narrow ocean chan ...
s; # It has essentially the same water level in all parts (except for relatively short-lived variations caused by wind, varying ice cover, large inflows, etc.); # It does not have regular intrusion of
seawater Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has appro ...
; # A considerable portion of the
sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand ...
suspended in the water is captured by the basins (for this to happen they need to have a sufficiently small inflow-to-volume ratio); # The area measured at the mean water level exceeds an arbitrarily chosen threshold (for instance, one
hectare The hectare (; SI symbol: ha) is a non-SI metric unit of area equal to a square with 100- metre sides (1 hm2), or 10,000 m2, and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. An acre i ...
). With the exception of criterion 3, the others have been accepted or elaborated upon by other hydrology publications.


Distribution

The majority of lakes on Earth are
freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does incl ...
, and most lie in the
Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...
at higher
latitude In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north ...
s.
Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...
, with a deranged drainage system, has an estimated 31,752 lakes larger than in surface area. The total number of lakes in Canada is unknown but is estimated to be at least 2 million.
Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bot ...
has 187,888 lakes of in area, or larger, of which 56,000 are large ( or larger). Most lakes have at least one natural outflow in the form of a
river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of ...
or
stream A stream is a continuous body of surface water flowing within the bed and banks of a channel. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long large streams ...
, 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. These are termed
endorheic An endorheic basin (; also spelled endoreic basin or endorreic basin) is a drainage basin that normally retains water and allows no outflow to other external bodies of water, such as rivers or oceans, but drainage converges instead into lakes ...
lakes. Many lakes are artificial and are constructed for
hydroelectric Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined an ...
power generation, aesthetic purposes,
recreation Recreation is an activity of leisure, leisure being discretionary time. The "need to do something for recreation" is an essential element of human biology and psychology. Recreational activities are often done for enjoyment, amusement, or plea ...
al purposes, industrial use, agricultural use, or domestic
water supply Water supply is the provision of water by public utilities, commercial organisations, community endeavors or by individuals, usually via a system of pumps and pipes. Public water supply systems are crucial to properly functioning societies. Th ...
. The number of lakes on Earth is undetermined because most lakes and ponds are very small and do not appear on maps or
satellite imagery Satellite images (also Earth observation imagery, spaceborne photography, or simply satellite photo) are images of Earth collected by imaging satellites operated by governments and businesses around the world. Satellite imaging companies sell ima ...
. Despite this uncertainty, a large number of studies agree that small ponds are much more abundant than large lakes. For example, one widely cited study estimated that Earth has 304 million lakes and ponds, and that 91% of these are or less in area. Despite the overwhelming abundance of ponds, almost all of Earth's lake water is found in fewer than 100 large lakes; this is because lake volume
scales Scale or scales may refer to: Mathematics * Scale (descriptive set theory), an object defined on a set of points * Scale (ratio), the ratio of a linear dimension of a model to the corresponding dimension of the original * Scale factor, a number w ...
superlinearly with lake area. Extraterrestrial lakes exist on the moon
Titan Titan most often refers to: * Titan (moon), the largest moon of Saturn * Titans, a race of deities in Greek mythology Titan or Titans may also refer to: Arts and entertainment Fictional entities Fictional locations * Titan in fiction, fictiona ...
, which orbits the planet Saturn. The shape of lakes on Titan is very similar to those on Earth. Lakes were formerly present on the surface of Mars, but are now dry lake beds.


Types

In 1957, G. Evelyn Hutchinson published a monograph titled ''A Treatise on Limnology'', which is regarded as a landmark discussion and classification of all major lake types, their origin, morphometric characteristics, and distribution. Hutchinson presented in his publication a comprehensive analysis of the origin of lakes and proposed what is a widely accepted classification of lakes according to their origin. This classification recognizes 11 major lake types that are divided into 76 subtypes. The 11 major lake types are: * tectonic lakes * volcanic lakes * glacial lakes * fluvial lakes * solution lakes * landslide lakes * aeolian lakes * shoreline lakes * organic lakes * anthropogenic lakes * meteorite (extraterrestrial impact) lakes


Tectonic lakes

Tectonic lakes are lakes formed by the deformation and resulting lateral and vertical movements of the Earth's crust. These movements include faulting, tilting, folding, and warping. Some of the largest lakes on Earth are rift lakes occupying rift valleys, e.g. Central African Rift lakes and Lake Baikal. Other well-known tectonic lakes,
Caspian Sea The Caspian Sea is the world's largest inland body of water, often described as the world's largest lake or a full-fledged sea. An endorheic basin, it lies between Europe and Asia; east of the Caucasus, west of the broad steppe of Central A ...
, the Sea of Aral, and other lakes from the Pontocaspian occupy basins that have been separated from the sea by the tectonic uplift of the sea floor above the ocean level. Often, the tectonic action of crustal extension has created an alternating series of parallel
graben In geology, a graben () is a depressed block of the crust of a planet or moon, bordered by parallel normal faults. Etymology ''Graben'' is a loan word from German, meaning 'ditch' or 'trench'. The word was first used in the geologic conte ...
s and horsts that form elongate basins alternating with mountain ranges. Not only does this promote the creation of lakes by the disruption of preexisting drainage networks, it also creates within arid regions endorheic basins that contain
salt lakes A salt lake or saline lake is a landlocked body of water that has a concentration of salts (typically sodium chloride) and other dissolved minerals significantly higher than most lakes (often defined as at least three grams of salt per litre). ...
(also called saline lakes). They form where there is no natural outlet, a high evaporation rate and the drainage surface of the
water table The water table is the upper surface of the zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with water. It can also be simply explained as the depth below which the ground is saturated. T ...
has a higher-than-normal
salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quant ...
content. Examples of these salt lakes include Great Salt Lake and the Dead Sea. Another type of tectonic lake caused by faulting is sag ponds.


Volcanic lakes

Volcanic lakes are lakes that occupy either local depressions, e.g. craters and maars, or larger basins, e.g.
calderas A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...
, created by volcanism. 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 a combination of both. Sometimes the latter are called caldera lakes, although often no distinction is made. An example is Crater Lake in
Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...
, in the caldera of Mount Mazama. The caldera was created in a massive volcanic eruption that led to the subsidence of Mount Mazama around 4860 BCE. Other volcanic lakes are created when either rivers or streams are dammed by lava flows or volcanic
lahar A lahar (, from jv, ꦮ꧀ꦭꦲꦂ) is a violent type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris and water. The material flows down from a volcano, typically along a river valley. Lahars are extr ...
s. The basin which is now Malheur Lake,
Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...
was created when a lava flow dammed the Malheur River. Among all lake types, volcanic crater lakes most closely approximate a circular shape.


Glacial lakes

Glacial lakes are lakes created by the direct action of glaciers and continental ice sheets. A wide variety of glacial processes create enclosed basins. As a result, there are a wide variety of different types of glacial lakes and it is often difficult to define clear-cut distinctions between different types of glacial lakes and lakes influenced by other activities. The general types of glacial lakes that have been recognized are lakes in direct contact with ice, glacially carved rock basins and depressions, morainic and outwash lakes, and glacial drift basins. Glacial lakes are the most numerous lakes in the world. Most lakes in northern Europe and North America have been either influenced or created by the latest, but not last, glaciation, to have covered the region. Glacial lakes include proglacial lakes, subglacial lakes, finger lakes, and epishelf lakes. Epishelf lakes are highly stratified lakes in which a layer of freshwater, derived from ice and snow melt, is dammed behind an ice shelf that is attached to the coastline. They are mostly found in Antarctica.


Fluvial lakes

Fluvial (or riverine) lakes are lakes produced by running water. These lakes include plunge pool lakes, fluviatile dams and meander lakes.


Oxbow lakes

The most common type of fluvial lake is 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. 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. Their crescent shape gives oxbow lakes a higher perimeter to area ratio than other lake types.


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 A levee (), dike (American English), dyke (Commonwealth English), embankment, floodbank, or stop bank is a structure that is usually earthen and that often runs parallel to the course of a river in its floodplain or along low-lying coastli ...
.


Floodplain lakes

Lakes formed by other processes responsible for
floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...
basin creation. During high floods they are flushed with river water. There are four types: 1. Confluent floodplain lake, 2. Contrafluent-confluent floodplain lake, 3. Contrafluent floodplain lake, 4. Profundal floodplain lake.


Solution lakes

A solution lake is a 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
sinkhole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are locally also known as ''vrtače'' and shakeholes, and to openi ...
s that form part of the local
karst topography Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathering-resistant ro ...
. Where
groundwater Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit ...
lies near the grounds surface, a sinkhole will be filled water as a solution lake. If such a lake consists of a large area of standing water that occupies an extensive closed depression in limestone, it is also called a karst lake. Smaller solution lakes that consist of a body of standing water in a closed depression within a karst region are known as ''karst ponds.''Neuendorf, K.K.E., Mehl Jr., J.P., and Jackson, J.A. (2005). ''Glossary of Geology,'' 5th revised and enlarged ed. Berlin: Springer. Approx. . Limestone caves often contain pools of standing water, which are known as '' underground lakes.'' Classic examples of solution lakes are abundant in the karst regions at the Dalmatian coast of
Croatia , image_flag = Flag of Croatia.svg , image_coat = Coat of arms of Croatia.svg , anthem = " Lijepa naša domovino"("Our Beautiful Homeland") , image_map = , map_caption = , capi ...
and within large parts of
Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and ...
.


Landslide lakes

A landslide lake is created by the
blockage ''Blockage'' (Persian: سد معبر, romanized: Sade Ma'bar) is a 2017 Iranian drama film directed by Mohsen Gharaie and written by Saeed Roustayi. The film screened for the first time at the 35th Fajr Film Festival and received 4 nominations. I ...
of a river valley by either mudflows, rockslides, or screes. Such lakes are most common in mountainous regions. Although landslide lakes may be large and quite deep, they are typically short-lived. An example of a landslide lake is Quake Lake, which formed as a result of the 1959 Hebgen Lake earthquake. Most landslide lakes disappear in the first few months after formation, but a landslide dam can burst suddenly at a later stage and threaten the population downstream when the lake water drains out. In 1911, an earthquake triggered a landslide that blocked a deep valley in the Pamir Mountains region of
Tajikistan Tajikistan (, ; tg, Тоҷикистон, Tojikiston; russian: Таджикистан, Tadzhikistan), officially the Republic of Tajikistan ( tg, Ҷумҳурии Тоҷикистон, Jumhurii Tojikiston), is a landlocked country in Centr ...
, forming the Sarez Lake. The Usoi Dam at the base of the valley has remained in place for more than 100 years but the terrain below the lake is in danger of a catastrophic flood if the dam were to fail during a future earthquake. Tal-y-llyn Lake in north
Wales Wales ( cy, Cymru ) is a country that is part of the United Kingdom. It is bordered by England to the east, the Irish Sea to the north and west, the Celtic Sea to the south west and the Bristol Channel to the south. It had a population in ...
is a landslide lake dating back to the last glaciation in Wales some 20000 years ago.


Aeolian lakes

Aeolian lakes are produced by wind action. These lakes are found mainly in
arid A region is arid when it severely lacks available water, to the extent of hindering or preventing the growth and development of plant and animal life. Regions with arid climates tend to lack vegetation and are called xeric or desertic. Most ...
environments, although some aeolian lakes are relict landforms indicative of arid paleoclimates. Aeolian lakes consist of lake basins dammed by wind-blown sand; interdunal lakes that lie between well-oriented
sand dune A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, f ...
s; and deflation basins formed by wind action under previously arid paleoenvironments. Moses Lake in
Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...
, United States, was originally a shallow natural lake and an example of a lake basin dammed by wind-blown sand. China's Badain Jaran Desert is a unique landscape of megadunes and elongated interdunal aeolian lakes, particularly concentrated in the southeastern margin of the desert.


Shoreline lakes

Shoreline lakes are generally lakes created by blockage of estuaries or by the uneven accretion of beach ridges by longshore and other currents. They include maritime coastal lakes, ordinarily in drowned estuaries; lakes enclosed by two tombolos or spits connecting an island to the mainland; lakes cut off from larger lakes by a bar; or lakes divided by the meeting of two spits.


Organic lakes

Organic lakes are lakes created by the actions of plants and animals. On the whole they are relatively rare in occurrence and quite small in size. In addition, they typically ephemeral features relative to the other types of lakes. The basins in which organic lakes occur are associated with beaver dams, coral lakes, or dams formed by vegetation.


Peat lakes

Peat Peat (), also known as turf (), is an accumulation of partially Decomposition, decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, Moorland, moors, or muskegs. The peatland ecosystem covers and ...
lakes are a form of organic lake. They form where a buildup of partly decomposed plant material in a wet environment leaves the vegetated surface below the
water table The water table is the upper surface of the zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with water. It can also be simply explained as the depth below which the ground is saturated. T ...
for a sustained period of time. They are often low in nutrients and mildly acidic, with bottom waters low in dissolved oxygen.


Anthropogenic lakes

Anthropogenic lakes are artificially created as a result of human activity. They can be formed by the intentional damming of rivers and streams or the subsequent filling of abandoned excavations by either ground water, precipitation, or a combination of both. The Upper Silesian region of Southern Poland contains an anthropogenic lake district consisting of more than 4,000 water bodies created by human activity. The diverse origins of these lakes include: reservoirs retained by dams, flooded mines, water bodies formed in subsidence basins and hollows,
levee A levee (), dike (American English), dyke (Commonwealth English), embankment, floodbank, or stop bank is a structure that is usually earthen and that often runs parallel to the course of a river in its floodplain or along low-lying coastli ...
ponds, and residual water bodies following river regulation.


Meteorite (extraterrestrial impact) lakes

Meteorite lakes, also known as ''crater lakes'' (not to be confused with volcanic crater lakes), are created by catastrophic impacts with the Earth by extraterrestrial objects (either
meteorite A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet or moon. When the original object ...
s or asteroids). Examples of meteorite lakes are Lonar Lake in India,
Lake El'gygytgyn Lake El'gygytgyn (Russian and Chukchi: Эльгыгытгын) is an impact crater lake located in the Chukotka Autonomous Okrug in northeast Siberia, about southeast of Chaunskaya Bay. The word "Elgygytgyn" means "white lake" in the Chukchi l ...
in northeast Siberia, and the
Pingualuit crater The Pingualuit Crater (french: Cratère des Pingualuit; from Inuit "pimple"), formerly called the "Chubb Crater" and later the "New Quebec Crater" (french: Cratère du Nouveau-Québec), is a relatively young impact crater located on the Ungava Pe ...
lake in Quebec, Canada. As in the cases of El'gygytgyn and Pingualuit, meteorite lakes can contain unique and scientifically valuable sedimentary deposits associated with long records of paleoclimatic changes.


Other classification methods

In addition to the mode of origin, lakes have been named and classified according to various other important factors such as thermal stratification, oxygen saturation, seasonal variations in lake volume and water level,
salinity Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...
of the water mass, relative seasonal permanence, degree of outflow, and so on. The names used by the lay public and in the scientific community for different types of lakes are often informally derived from the morphology of the lakes' physical characteristics or other factors. Also, different cultures and regions of the world have their own popular nomenclature.


By thermal stratification

One important method of lake classification is on the basis of thermal stratification, which has a major influence on the animal and plant life inhabiting a lake, and the fate and distribution of dissolved and suspended material in the lake. For example, the thermal stratification, as well as the degree and frequency of mixing, has a strong control over the distribution of oxygen within the lake. Professor F.-A. Forel,Forel, F.A., 1901. ''Handbuch der Seenkunde. Allgemeine Limnologie.'' J. von Engelhorn, Stuttgart, Germany. also referred to as the "Father of limnology", was the first scientist to classify lakes according to their thermal stratification. His system of classification was later modified and improved upon by Hutchinson and Löffler. As the
density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematicall ...
of water varies with temperature, with a maximum at +4 degrees Celsius, thermal stratification is an important physical characteristic of a lake that controls the
fauna Fauna is all of the animal life present in a particular region or time. The corresponding term for plants is '' flora'', and for fungi, it is '' funga''. Flora, fauna, funga and other forms of life are collectively referred to as '' biota''. ...
and
flora Flora is all the plant life present in a particular region or time, generally the naturally occurring ( indigenous) native plants. Sometimes bacteria and fungi are also referred to as flora, as in the terms '' gut flora'' or '' skin flora''. ...
, sedimentation, chemistry, and other aspects of individual lakes. First, the colder, denser water typically forms a layer near the bottom, which is called the '' hypolimnion''. Second, normally overlying the hypolimnion is a transition zone known as the ''
metalimnion A thermocline (also known as the thermal layer or the metalimnion in lakes) is a thin but distinct layer in a large body of fluid (e.g. water, as in an ocean or lake; or air, e.g. an atmosphere) in which temperature changes more drastically with ...
''. Finally, overlying the metalimnion is a surface layer of warmer water with a lower density, called the '' epilimnion''. This typical stratification sequence can vary widely, depending on the specific lake or the time of year, or a combination of both. The classification of lakes by thermal stratification presupposes lakes with sufficient depth to form a hypolimnion; accordingly, very shallow lakes are excluded from this classification system. Based upon their thermal stratification, lakes are classified as either '' holomictic'', with a uniform temperature and density from top to bottom at a given time of year, or '' meromictic'', with layers of water of different temperature and density that do not intermix. The deepest layer of water in a meromictic lake does not contain any dissolved oxygen so there are no living
aerobic organism Aerobic means "requiring air," in which "air" usually means oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, ...
s. Consequently, the layers of sediment at the bottom of a meromictic lake remain relatively undisturbed, which allows for the development of
lacustrine deposits Lacustrine deposits are sedimentary rock formations which formed in the bottom of ancient lakes. A common characteristic of lacustrine deposits is that a river or stream channel has carried sediment into the basin. Lacustrine deposits form in all ...
. In a holomictic lake, the uniformity of temperature and density allows the lake waters to completely mix. Based upon thermal stratification and frequency of turnover, holomictic lakes are divided into amictic lakes, cold monomictic lakes, dimictic lakes, warm monomictic lakes, polymictic lakes, and oligomictic lakes. Lake stratification does not always result from a variation in density because of thermal gradients. Stratification can also result from a density variation caused by gradients in salinity. In this case, the hypolimnion and epilimnion are separated not by a thermocline but by a ''
halocline In oceanography, a halocline (from Greek ''hals'', ''halos'' 'salt' and ''klinein'' 'to slope') is a cline, a subtype of chemocline caused by a strong, vertical salinity gradient within a body of water. Because salinity (in concert with te ...
'', which is sometimes referred to as a ''
chemocline A chemocline is a type of cline, a layer of fluid with different properties, characterized by a strong, vertical chemistry gradient within a body of water. In bodies of water where chemoclines occur, the cline separates the upper and lower layer ...
''.


By seasonal variations in water level and volume

Lakes are informally classified and named according to the seasonal variation in their lake level and volume. Some of the names include: * Ephemeral lake is a short-lived lake or pond. If it fills with water and dries up (disappears) seasonally it is known as an ''intermittent lake''Poehls, D.J. and Smith, G.J. eds. (2009). ''Encyclopedic dictionary of hydrogeology.'' Academic Press. p. 517. They often fill
polje A polje, also karst polje or karst field, is a large flat plain found in karstic geological regions of the world, with areas usually . The name derives from the Slavic languages and literally means 'field', whereas in English ''polje'' specif ...
s. *
Dry lake A dry lake bed, also known as a playa, is a basin or depression that formerly contained a standing surface water body, which disappears when evaporation processes exceeds recharge. If the floor of a dry lake is covered by deposits of alkaline c ...
is a popular name for an ephemeral lake that contains water only intermediately at irregular and infrequent intervals.Last, W.M. and Smol, J.P. (2001). ''Tracking environmental change using lake sediments. Volume 1: basin analysis, coring, and chronological techniques.'' Springer Science & Business Media. * Perennial lake is a lake that has water in its basin throughout the year and is not subject to extreme fluctuations in level.Gangstad, E.O., (1979)
''Glossary of Biolimnological Terms''
Washington, DC, United States Army Corps of Engineers.
* Playa lake is a typically shallow, intermittent lake that covers or occupies a playa either in wet seasons or in especially wet years but subsequently drying up in an arid or semiarid region. * Vlei is a name used in
South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring coun ...
for a shallow lake which varies considerably in level with the seasons.Theal, G.M., 1877. ''Compendium of South African history and geography, 3rd.'' Institution Press, Lovedale, South Africa.


By water chemistry

Lakes may be informally classified and named according to the general chemistry of their water mass. Using this classification method, the lake types include: * An ''acid lake'' contains water with a below-neutral pH of less than 6.5. A lake is considered to be highly acidic if its pH drops below 5.5, leading to biological consequences. Such lakes include: acidic ''pit lakes'' occupying abandoned mines and excavations; naturally acidic lakes of
igneous Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or ...
and metamorphic landscapes; peat bogs in northern regions; ''crater lakes'' of active and dormant volcanoes; and lakes acidified by
acid rain Acid rain is rain or any other form of precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH). Most water, including drinking water, has a neutral pH that exists between 6.5 and 8.5, but ac ...
.Geller, W. et al. (eds.) (2013). ''Acidic Pit Lakes, Environmental Science and Engineering'', Springer-Verlag Berlin HeidelbergRouwet, D. et al. (eds.) (2015). ''Volcanic Lakes, Advances in Volcanology,'' Springer-Verlag Berlin Heidelberg * A ''salt lake'', also known as a ''saline lake'' or ''brine lake'', is an inland body of water situated in an arid or semiarid region, with no outlet to the sea, containing a high concentration of dissolved neutral salts (principally
sodium chloride Sodium chloride , commonly known as salt (although sea salt also contains other chemical salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of 22.99 and 35. ...
). Examples include the Great Salt Lake in Utah, and the Dead Sea in southwestern Asia. * An '' alkali sink'', also known as an ''alkali flat'' or ''salt flat'', is a shallow saline feature that can be found in low-lying areas of arid regions and in groundwater discharge zones. These features are typically classified as ''dry lakes'', or ''playas'', because they are periodically flooded by rain or flood events and then dry up during drier intervals, leaving accumulations of brines and evaporitic minerals. * A '' salt pan'' is a small shallow natural depression in which water accumulates and evaporates, leaving a salt deposit, or the shallow lake of brackish water that occupies a salt pan. (The term "salt pan" comes from open-pan salt making, a method of extracting salt from brine using large open pans.) * A ''saline pan'' is another name for an
ephemeral acid saline lake An ephemeral acid saline lake is a lake that is relatively high in dissolved salts and has a low pH, usually within the range of 25%, nearly 8 times that of seawater. Most of the Western Australian waters are sodium chloride (NaCl) brines with va ...
which precipitates a bottom crust that is subsequently modified during subaerial exposure.


Composed of other liquids

*
Lava lake Lava lakes are large volumes of molten lava, usually basaltic, contained in a volcanic vent, crater, or broad depression. The term is used to describe both lava lakes that are wholly or partly molten and those that are solidified (someti ...
is a large volume of molten lava, usually basaltic, contained in a volcanic vent, crater, or broad depression. * Hydrocarbon lakes are bodies of liquid ethane and
methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane ...
that occupy depressions on the surface of
Titan Titan most often refers to: * Titan (moon), the largest moon of Saturn * Titans, a race of deities in Greek mythology Titan or Titans may also refer to: Arts and entertainment Fictional entities Fictional locations * Titan in fiction, fictiona ...
. They were detected by the Cassini–Huygens space probe.


Paleolakes

A paleolake (also palaeolake) is a lake that existed in the past when hydrological conditions were different. Quaternary paleolakes can often be identified on the basis of relict lacustrine landforms, such as relict lake plains and coastal landforms that form recognizable relict shorelines called '' paleoshorelines.'' Paleolakes can also be recognized by characteristic
sedimentary Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...
deposits that accumulated in them and any
fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
s that might be contained in these sediments. The paleoshorelines and sedimentary deposits of paleolakes provide evidence for prehistoric hydrological changes during the times that they existed.Goudie, A. (2008). "Arid Climates and Indicators". Gornitz, V. ed., ''Encyclopedia of paleoclimatology and ancient environments''. Springer Science & Business Media. pp. 45–51. There are two types of paleolake: * A
former lake A former is an object, such as a template, gauge or cutting die, which is used to form something such as a boat's hull. Typically, a former gives shape to a structure that may have complex curvature. A former may become an integral part of the ...
is a paleolake that no longer exists. Such lakes include prehistoric lakes and those that have permanently dried up, often as the result of either
evaporation Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when h ...
or human intervention. An example of a former lake is Owens Lake in California, United States. Former lakes are a common feature of the Basin and Range area of southwestern North America. * A shrunken lake is a paleolake that still exists but has considerably decreased in size over geological time. An example of a shrunken lake is
Lake Agassiz Lake Agassiz was a large glacial lake in central North America. Fed by glacial meltwater at the end of the last glacial period, its area was larger than all of the modern Great Lakes combined. First postulated in 1823 by William H. Keating, i ...
, which once covered much of central North America. Two notable remnants of Lake Agassiz are
Lake Winnipeg Lake Winnipeg (french: Lac Winnipeg, oj, ᐑᓂᐸᑲᒥᐠᓴᑯ˙ᑯᐣ, italics=no, Weenipagamiksaguygun) is a very large, relatively shallow lake in North America, in the province of Manitoba, Canada. Its southern end is about north of ...
and Lake Winnipegosis. Paleolakes are of scientific and economic importance. For example, Quaternary paleolakes in semidesert basins are important for two reasons: they played an extremely significant, if transient, role in shaping the floors and
piedmont it, Piemontese , population_note = , population_blank1_title = , population_blank1 = , demographics_type1 = , demographics1_footnotes = , demographics1_title1 = , demographics1_info1 = , demographics1_title2 ...
s of many basins; and their sediments contain enormous quantities of geologic and
paleontologic Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (geology), epoch (roughly 11,700 years before present). It includes t ...
information concerning past environments. In addition, the organic-rich deposits of pre-Quaternary paleolakes are important either for the thick deposits of oil shale and shale gas contained in them, or as source rocks of
petroleum Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ...
and
natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbon d ...
. Although of significantly less economic importance, strata deposited along the shore of paleolakes sometimes contain
coal seam Coal mining is the process of extracting coal from the ground. Coal is valued for its energy content and since the 1880s has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron fro ...
s.Gierlowski-Kordesch, E. and Kelts, K.R. eds. (2000). ''Lake Basins Through Space and Time''. AAPG Studies in Geology 46 (No. 46). The American Association of Petroleum Geologists, Tulsa, OK


Characteristics

Lakes have numerous features in addition to lake type, such as
drainage basin A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, ...
(also known as catchment area), inflow and outflow,
nutrient A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excre ...
content, dissolved oxygen, pollutants, pH, and
sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand ...
ation. Changes in the level of a lake are controlled by the difference between the input and output compared to the total volume of the lake. Significant input sources are precipitation onto the lake, runoff carried by streams and channels from the lake's
catchment A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, ...
area,
groundwater Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit ...
channels and aquifers, and artificial sources from outside the catchment area. Output sources are evaporation from the lake, surface and groundwater flows, and any extraction of lake water by humans. As climate conditions and human water requirements vary, these will create fluctuations in the lake level. Lakes can be also categorized on the basis of their richness in nutrients, which typically affect plant growth. Nutrient-poor lakes are said to be '' oligotrophic'' and are generally clear, having a low concentration of plant life. '' Mesotrophic lakes'' have good clarity and an average level of nutrients. '' Eutrophic'' lakes are enriched with nutrients, resulting in good plant growth and possible algal blooms. '' Hypertrophic'' lakes are bodies of water that have been excessively enriched with nutrients. These lakes typically have poor clarity and are subject to devastating algal blooms. Lakes typically reach this condition due to human activities, such as heavy use of fertilizers in the lake catchment area. Such lakes are of little use to humans and have a poor
ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...
due to decreased dissolved oxygen. Due to the unusual relationship between water's
temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...
and its
density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematicall ...
, lakes form layers called thermoclines, layers of drastically varying temperature relative to depth. Fresh water is most dense at about 4 degrees Celsius (39.2 °F) at sea level. When the temperature of the water at the surface of a lake reaches the same temperature as deeper water, as it does during the cooler months in temperate climates, the water in the lake can mix, bringing oxygen-starved water up from the depths and bringing oxygen down to decomposing sediments. Deep temperate lakes can maintain a reservoir of cold water year-round, which allows some cities to tap that reservoir for deep lake water cooling. Since the surface water of deep
tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...
lakes never reaches the temperature of maximum density, there is no process that makes the water mix. The deeper layer becomes oxygen starved and can become saturated with carbon dioxide, or other gases such as sulfur dioxide if there is even a trace of volcanic activity. Exceptional events, such as earthquakes or landslides, can cause mixing which rapidly brings the deep layers up to the surface and release a vast cloud of gas which lay trapped in solution in the colder water at the bottom of the lake. This is called a limnic eruption. An example is the disaster at Lake Nyos in
Cameroon Cameroon (; french: Cameroun, ff, Kamerun), officially the Republic of Cameroon (french: République du Cameroun, links=no), is a country in west-central Africa. It is bordered by Nigeria to the west and north; Chad to the northeast; the ...
. The amount of gas that can be dissolved in water is directly related to pressure. As deep water surfaces, the pressure drops and a vast amount of gas comes out of solution. Under these circumstances carbon dioxide is hazardous because it is heavier than air and displaces it, so it may flow down a river valley to human settlements and cause mass
asphyxiation Asphyxia or asphyxiation is a condition of deficient supply of oxygen to the body which arises from abnormal breathing. Asphyxia causes generalized hypoxia, which affects primarily the tissues and organs. There are many circumstances that can ...
. The material at the bottom of a lake, or ''lake bed'', may be composed of a wide variety of inorganics, such as
silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel ...
or
sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class ...
, and organic material, such as decaying plant or animal matter. The composition of the lake bed has a significant impact on the flora and fauna found within the lake's environs by contributing to the amounts and the types of nutrients available. A paired (black and white) layer of the varved lake sediments correspond to a year. During winter, when organisms die, carbon is deposited down, resulting to a black layer. At the same year, during summer, only few organic materials are deposited, resulting to a white layer at the lake bed. These are commonly used to track past paleontological events. Natural lakes provide a
microcosm Microcosm or macrocosm, also spelled mikrokosmos or makrokosmos, may refer to: Philosophy * Microcosm–macrocosm analogy, the view according to which there is a structural similarity between the human being and the cosmos Music * Macrocosm (al ...
of living and nonliving elements that are relatively independent of their surrounding environments. Therefore, lake organisms can often be studied in isolation from the lake's surroundings.


Limnology

Limnology Limnology ( ; from Greek λίμνη, ''limne'', "lake" and λόγος, ''logos'', "knowledge") is the study of inland aquatic ecosystems. The study of limnology includes aspects of the biological, chemical, physical, and geological characteris ...
is the study of inland bodies of water and related ecosystems. Limnology divides lakes into three zones: the ''
littoral zone The littoral zone or nearshore is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely inundated), to coastal ...
'', a sloped area close to land; the ''
photic The photic zone, euphotic zone, epipelagic zone, or sunlight zone is the uppermost layer of a body of water that receives sunlight, allowing phytoplankton to perform photosynthesis. It undergoes a series of physical, chemical, and biological pro ...
'' or ''open-water zone'', where sunlight is abundant; and the deep-water ''
profundal The profundal zone is a deep zone of an inland body of freestanding water, such as a lake or pond, located below the range of effective light penetration. This is typically below the thermocline, the vertical zone in the water through which te ...
'' or ''
benthic zone The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning " ...
'', where little sunlight can reach. The depth to which light can penetrate depends on the turbidity of the water, which is determined by the density and size of suspended particles. A particle will be in suspension if its weight is less than the random turbidity
force In physics, a force is an influence that can change the motion of an object. A force can cause an object with mass to change its velocity (e.g. moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a ...
s acting upon it. These particles can be sedimentary or
biological Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary in ...
in origin (including
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular micr ...
and
detritus In biology, detritus () is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts comm ...
) and are responsible for the color of the water. Decaying plant matter, for instance, may account for a yellow or brown color, while algae may cause a greenish coloration. In very shallow water bodies, iron oxides make the water reddish brown. Bottom-dwelling detritivorous fish stir the mud in search of food and can be the cause of turbid waters. Piscivorous fish contribute to turbidity by eating plant-eating (
plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a cruc ...
ivorous) fish, thus increasing the amount of algae (see aquatic trophic cascade). The light depth or transparency is measured using a ''
Secchi disk The Secchi disk (or Secchi disc), as created in 1865 by Angelo Secchi, is a plain white, circular disk in diameter used to measure water transparency or turbidity in bodies of water. The disc is mounted on a pole or line, and lowered slowly down ...
'', a 20-cm (8 in) disk with alternating white and black quadrants. The depth at which the disk is no longer visible is the ''Secchi depth'', a measure of transparency. The Secchi disk is commonly used to test for eutrophication. For a detailed look at these processes, see lentic ecosystems. A lake moderates the surrounding region's temperature and
climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologi ...
because water has a very high
specific heat capacity In thermodynamics, the specific heat capacity (symbol ) of a substance is the heat capacity of a sample of the substance divided by the mass of the sample, also sometimes referred to as massic heat capacity. Informally, it is the amount of heat t ...
(4,186 J·kg−1·K−1). In the daytime a lake can cool the land beside it with local winds, resulting in a
sea breeze A sea breeze or onshore breeze is any wind that blows from a large body of water toward or onto a landmass; it develops due to differences in air pressure created by the differing heat capacities of water and dry land. As such, sea breezes a ...
; in the night it can warm it with a land breeze.


Biological properties

Lake zones: * ''Epilittoral'': The zone that is entirely above the lake's normal water level and never submerged by lake water * ''Littoral'': The zone that encompasses the small area above the normal water level (which is sometimes submerged when the lake's water level increases), reaching to the deepest part of the lake that still allows for submerged macrophytic growth * ''Littoriprofundal'': Transition zone commonly aligned with stratified lakes' metalimnions – too deep for macrophytes but includes photosynthetic algae and bacteria * ''Profundal'': Sedimentary zone containing no vegetation Algal community types: * ''Epipelic'': Algae that grow on sediments * ''Epilithic'': Algae that grow on rocks * ''Epipsammic'': Algae that grow on (or within) sand * ''Epiphytic'': Algae that grow on macrophytes * ''Epizooic'': Algae that grow on living animals * ''Metaphyton'': Algae present in the littoral zone, not in a state of suspension nor attached to a substratum (such as a macrophyte)


Circulation


Flora and fauna


Disappearance

The lake may be infilled with deposited sediment and gradually become a
wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (Anoxic waters, anoxic) processes prevailing, especially in t ...
such as a
swamp A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in ...
or
marsh A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found ...
. 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 ''Sphagnum'' is a genus of approximately 380 accepted species of mosses, commonly known as sphagnum moss, peat moss, also bog moss and quacker moss (although that term is also sometimes used for peat). Accumulations of ''Sphagnum'' can store wa ...
when conditions are right, and animals, many of which are very rare. Gradually, the lake closes and young
peat Peat (), also known as turf (), is an accumulation of partially Decomposition, decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, Moorland, moors, or muskegs. The peatland ecosystem covers and ...
may form, forming a
fen A fen is a type of peat-accumulating wetland fed by mineral-rich ground or surface water. It is one of the main types of wetlands along with marshes, swamps, and bogs. Bogs and fens, both peat-forming ecosystems, are also known as mires ...
. In lowland river valleys where a river can
meander A meander is one of a series of regular sinuous curves in the channel of a river or other watercourse. It is produced as a watercourse erodes the sediments of an outer, concave bank ( cut bank) and deposits sediments on an inner, convex ban ...
, the presence of peat is explained by the infilling of historical oxbow lakes. In the final stages of
succession Succession is the act or process of following in order or sequence. Governance and politics *Order of succession, in politics, the ascension to power by one ruler, official, or monarch after the death, resignation, or removal from office of ...
, 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 and can be found in karstic terrain. A prime example of an intermittent lake is Lake Cerknica in
Slovenia Slovenia ( ; sl, Slovenija ), officially the Republic of Slovenia (Slovene: , abbr.: ''RS''), is a country in Central Europe. It is bordered by Italy to the west, Austria to the north, Hungary to the northeast, Croatia to the southeast, and ...
or Lag Prau Pulte in Graubünden. Other intermittent lakes are only the result of above-average precipitation in a closed, or endorheic basin, usually filling dry lake beds. This can occur in some of the driest places on earth, like
Death Valley Death Valley is a desert valley in Eastern California, in the northern Mojave Desert, bordering the Great Basin Desert. During summer, it is the hottest place on Earth. Death Valley's Badwater Basin is the point of lowest elevation in Nort ...
. This occurred in the spring of 2005, after unusually heavy rains. The lake did not last into the summer, and was quickly evaporated (see photos to right). A more commonly filled lake of this type is Sevier Lake of west-central
Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...
. Sometimes a lake will disappear quickly. On 3 June 2005, in
Nizhny Novgorod Oblast Nizhny Novgorod Oblast (russian: link=no, Нижегородская область, ''Nizhegorodskaya oblast''), is a federal subject of Russia (an oblast). Its administrative center is the city of Nizhny Novgorod. It has a population of 3,3 ...
, Russia, a lake called
Lake Beloye Lake Beloye or White LakeArukask, Madis, & Taisto-Kalevi Raudalainen. 2014. Autobiographical and Interpretive Dynamics in the Oral Repertoire of a Vepsian Woman. In: Marion Bowman & Ülo Valk (eds.), ''Vernacular Religion in Everyday Life: Expres ...
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. 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. Some lakes disappear because of human development factors. The shrinking
Aral Sea The Aral Sea ( ; kk, Арал теңізі, Aral teñızı; uz, Орол денгизи, Orol dengizi; kaa, Арал теңизи, Aral teńizi; russian: Аральское море, Aral'skoye more) was an endorheic lake lying between Kazak ...
is described as being "murdered" by the diversion for irrigation of the rivers feeding it.


Extraterrestrial lakes

Only one
astronomical body An astronomical object, celestial object, stellar object or heavenly body is a naturally occurring physical entity, association, or structure that exists in the observable universe. In astronomy, the terms ''object'' and ''body'' are often u ...
other than Earth is known to harbor large lakes: Saturn's largest moon,
Titan Titan most often refers to: * Titan (moon), the largest moon of Saturn * Titans, a race of deities in Greek mythology Titan or Titans may also refer to: Arts and entertainment Fictional entities Fictional locations * Titan in fiction, fictiona ...
. Photographs and
spectroscopic analysis Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matte ...
by the '' Cassini–Huygens''
spacecraft A spacecraft is a vehicle or machine designed to fly in outer space. A type of artificial satellite, spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, ...
show liquid ethane on the surface, which is thought to be mixed with liquid methane. The largest lake on Titan is Kraken Mare which, at an estimated 400,000 km2, is roughly five times the size of
Lake Superior Lake Superior in central North America is the largest freshwater lake in the world by surface areaThe Caspian Sea is the largest lake, but is saline, not freshwater. and the third-largest by volume, holding 10% of the world's surface fresh wa ...
(~80,000 km2) and nearly the size of all five
Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lakes ...
of North America combined. The second largest Titanean lake, Ligeia Mare, is almost twice the size of Lake Superior, at an estimated 150,000 km2. Jupiter's large moon Io is volcanically active, leading to the accumulation of
sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formul ...
deposits on the surface. Some photographs taken during the ''Galileo'' mission appear to show lakes of liquid sulfur in volcanic caldera, though these are more analogous to lakes of lava than of water on Earth. The planet
Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...
has only one confirmed lake which is underground and near the south pole. Although the surface of Mars is too cold and has too little atmospheric pressure to permit permanent surface water, geologic evidence appears to confirm that ancient lakes once formed on the surface. There are dark basaltic plains on the
Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
, similar to lunar maria but smaller, which are called ''lacus'' (singular ''lacus'',
Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...
for "lake") because they were thought by early astronomers to be lakes of water.


Notable lakes on Earth

* The largest lake by surface area is
Caspian Sea The Caspian Sea is the world's largest inland body of water, often described as the world's largest lake or a full-fledged sea. An endorheic basin, it lies between Europe and Asia; east of the Caucasus, west of the broad steppe of Central A ...
, which is despite its name considered as a lake from the point of view of geography. Its surface area is 143,000 sq. mi./371,000 km2. * The second largest lake by surface area, and the largest freshwater lake by surface area, is Lake Michigan-Huron, which is hydrologically a single lake. Its surface area is 45,300 sq. mi./117,400 km2. For those who consider Lake Michigan-Huron to be separate lakes, and Caspian Sea to be a
sea The sea, connected as the world ocean or simply the ocean, is the body of salty water that covers approximately 71% of the Earth's surface. The word sea is also used to denote second-order sections of the sea, such as the Mediterranean Sea, ...
,
Lake Superior Lake Superior in central North America is the largest freshwater lake in the world by surface areaThe Caspian Sea is the largest lake, but is saline, not freshwater. and the third-largest by volume, holding 10% of the world's surface fresh wa ...
would be the largest lake at 82,100 km2 (31,700 square miles) * Lake Baikal is the deepest lake in the world, located in
Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part ...
, with a bottom at . Its mean depth is also the greatest in the world ().
It is also the world's largest freshwater lake by volume (, but much smaller than the Caspian Sea at ), and the second longest (about from tip to tip). * The world's oldest lake is Lake Baikal, followed by Lake Tanganyika in
Tanzania Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great Lakes region. It borders Uganda to the north; Kenya to the northeast; Comoro Islands ...
. Lake Maracaibo is considered by some to be the second-oldest lake on Earth, but since it lies at
sea level Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardis ...
and nowadays is a contiguous body of water with the sea, others consider that it has turned into a small
bay A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean, a lake, or another bay. A large bay is usually called a gulf, sea, sound, or bight. A cove is a small, circular bay with a na ...
. * The longest lake is Lake Tanganyika, with a length of about (measured along the lake's center line).
It is also the third largest by volume, the second oldest, and the second deepest () in the world, after Lake Baikal. * The world's highest lake, if size is not a criterion, may be the crater lake of Ojos del Salado, at . * The highest large (greater than ) lake in the world is the Pumoyong Tso (Pumuoyong Tso), in the
Tibet Autonomous Region The Tibet Autonomous Region or Xizang Autonomous Region, often shortened to Tibet or Xizang, is a province-level autonomous region of the People's Republic of China in Southwest China. It was overlayed on the traditional Tibetan regions ...
of China, at , above sea level. * The world's highest commercially navigable lake is Lake Titicaca in
Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = National seal , national_motto = "Firm and Happy f ...
and
Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...
at . It is also the largest lake in South America. * The world's lowest lake is the Dead Sea, bordered by
Jordan Jordan ( ar, الأردن; tr. ' ), officially the Hashemite Kingdom of Jordan,; tr. ' is a country in Western Asia. It is situated at the crossroads of Asia, Africa, and Europe, within the Levant region, on the East Bank of the Jordan Rive ...
to the east and
Israel Israel (; he, יִשְׂרָאֵל, ; ar, إِسْرَائِيل, ), officially the State of Israel ( he, מְדִינַת יִשְׂרָאֵל, label=none, translit=Medīnat Yīsrāʾēl; ), is a country in Western Asia. It is situated ...
and Palestine to the west, at below sea level. It is also one of the lakes with highest
salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quant ...
concentration. * Lake Michigan–Huron has the longest lake coastline in the world: about , excluding the coastline of its many inner islands. Even if it is considered two lakes, Lake Huron alone would still have the longest coastline in the world at . * The largest island in a lake is Manitoulin Island in Lake Michigan-Huron, with a surface area of .
Lake Manitou Lake Manitou is the largest lake on Manitoulin Island in Ontario, Canada. With an area of , it is the largest lake on a lake island in the world. It is drained by the Manitou River. There are several small islands in Lake Manitou, such as Rope ...
, on Manitoulin Island, is the largest lake on an island in a lake. * The largest lake on an island is Nettilling Lake on
Baffin Island Baffin Island (formerly Baffin Land), in the Canadian territory of Nunavut, is the largest island in Canada and the fifth-largest island in the world. Its area is , slightly larger than Spain; its population was 13,039 as of the 2021 Canadia ...
, with an area of and a maximum length of . * The largest lake in the world that drains naturally in two directions is Wollaston Lake. * Lake Toba on the island of
Sumatra Sumatra is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the sixth-largest island in the world at 473,481 km2 (182,812 mi.2), not including adjacent i ...
is in what is probably the largest resurgent
caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...
on Earth. * The largest lake completely within the boundaries of a single city is Lake Wanapitei in the city of
Sudbury Sudbury may refer to: Places Australia * Sudbury Reef, Queensland Canada * Greater Sudbury, Ontario (official name; the city continues to be known simply as Sudbury for most purposes) ** Sudbury (electoral district), one of the city's federal el ...
,
Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...
, 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 The Dominican Republic ( ; es, República Dominicana, ) is a country located on the island of Hispaniola in the Greater Antilles archipelago of the Caribbean region. It occupies the eastern five-eighths of the island, which it shares with ...
is the only saltwater lake in the world inhabited by
crocodile Crocodiles (family Crocodylidae) or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to include all extant me ...
s. * Lake Bernard, Ontario, Canada, claims to be the largest lake in the world with no islands. *
Lake Saimaa Saimaa ( , ; sv, Saimen) is a lake located in the Finnish Lakeland area in southeastern Finland. At approximately , it is the largest lake in Finland, and the fourth largest natural freshwater lake in Europe. The name Saimaa likely comes fro ...
in both South Savonia and
South Karelia South Karelia ( fi, Etelä-Karjala; sv, Södra Karelen) is a region of Finland. It borders the regions of Kymenlaakso, South Savo and North Karelia, as well as Russia (Republic of Karelia and Leningrad Oblast). Historical province ''For his ...
, Finland, forms the much larger Saimaa basin, which have more shorelines per unit of area than anywhere else in the world, with the total length being nearly . * The largest lake in one country is
Lake Michigan Lake Michigan is one of the five Great Lakes of North America. It is the second-largest of the Great Lakes by volume () and the third-largest by surface area (), after Lake Superior and Lake Huron. To the east, its basin is conjoined with that o ...
, in the United States. However, it is sometimes considered part of Lake Michigan-Huron, making the record go to Great Bear Lake,
Northwest Territories The Northwest Territories (abbreviated ''NT'' or ''NWT''; french: Territoires du Nord-Ouest, formerly ''North-Western Territory'' and ''North-West Territories'' and namely shortened as ''Northwest Territory'') is a federal territory of Canada. ...
, in
Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...
, the largest lake within one jurisdiction. * The largest lake on an island in a lake on an island is Crater Lake on Vulcano Island in Lake Taal on the island of
Luzon Luzon (; ) is the largest and most populous island in the Philippines. Located in the northern portion of the Philippines archipelago, it is the economic and political center of the nation, being home to the country's capital city, Manila, as ...
, The
Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...
. * The northernmost named lake on Earth is Upper Dumbell Lake in the Qikiqtaaluk Region of
Nunavut Nunavut ( , ; iu, ᓄᓇᕗᑦ , ; ) is the largest and northernmost territory of Canada. It was separated officially from the Northwest Territories on April 1, 1999, via the '' Nunavut Act'' and the '' Nunavut Land Claims Agreement Act'' ...
,
Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...
at a latitude of 82°28'N. It is southwest of Alert, the northernmost settlement in the world. There are also several small lakes north of Upper Dumbell Lake, but they are all unnamed and only appear on very detailed maps.


Largest by continent

The largest lakes (surface area) by
continent A continent is any of several large landmasses. Generally identified by convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continents. Ordered from largest in area to smallest, these seven ...
are: * Australia –
Lake Eyre Lake Eyre ( ), officially known as Kati Thanda–Lake Eyre, is an endorheic lake in east-central Far North South Australia, some north of Adelaide. The shallow lake is the depocentre of the vast endorheic Lake Eyre basin, and contains ...
(salt lake) * Africa –
Lake Victoria Lake Victoria is one of the African Great Lakes. With a surface area of approximately , Lake Victoria is Africa's largest lake by area, the world's largest tropical lake, and the world's second-largest fresh water lake by surface area after ...
, also the third-largest freshwater lake on Earth. It is one of the
Great Lakes of Africa The African Great Lakes ( sw, Maziwa Makuu; rw, Ibiyaga bigari) are a series of lakes constituting the part of the Rift Valley lakes in and around the East African Rift. They include Lake Victoria, the second-largest fresh water lake in the wo ...
. * Antarctica – Lake Vostok (subglacial) * Asia – Lake Baikal (if the
Caspian Sea The Caspian Sea is the world's largest inland body of water, often described as the world's largest lake or a full-fledged sea. An endorheic basin, it lies between Europe and Asia; east of the Caucasus, west of the broad steppe of Central A ...
is considered a lake, it is the largest in Eurasia, but is divided between the two geographic continents) * Oceania –
Lake Eyre Lake Eyre ( ), officially known as Kati Thanda–Lake Eyre, is an endorheic lake in east-central Far North South Australia, some north of Adelaide. The shallow lake is the depocentre of the vast endorheic Lake Eyre basin, and contains ...
when filled; the largest permanent (and freshwater) lake in Oceania is Lake Taupo. * Europe – Lake Ladoga, followed by Lake Onega, both in northwestern Russia. * North America – Lake Michigan–Huron, which is hydrologically a single lake. However, lakes
Huron Huron may refer to: People * Wyandot people (or Wendat), indigenous to North America * Wyandot language, spoken by them * Huron-Wendat Nation, a Huron-Wendat First Nation with a community in Wendake, Quebec * Nottawaseppi Huron Band of Potawato ...
and
Michigan Michigan () is a state in the Great Lakes region of the upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the 10th-largest state by population, the 11th-largest by area, and t ...
are usually considered separate lakes, in which case
Lake Superior Lake Superior in central North America is the largest freshwater lake in the world by surface areaThe Caspian Sea is the largest lake, but is saline, not freshwater. and the third-largest by volume, holding 10% of the world's surface fresh wa ...
would be the largest. * South America – Lake Titicaca, which is also the highest navigable body of water on Earth at above sea level. The much larger Lake Maracaibo is much older, but perceived by some to no longer be genuinely a lake for multiple reasons.


See also


Notes


References


External links


ILEC World Lake Database

LakeNet Global Lake Database
{{Authority control Bodies of water Lacustrine landforms