Misplaced Pages

#948051

87-478: The term lake is used to mean a body of primarily fresh water. A sea is filled with brackish or salt water. In the history of the Baltic Sea, the distinction is not always clear. Salinity has varied with location, depth and time. Currently the Baltic Sea has different salinity in layers, seasons and distance from its North Sea connection, as well as mixing events separated by decades. The saline gradients across

174-509: A glacial lake outburst flood in a narrow corridor in the region of Mount Billingen in present-day south-west Sweden; from the 1920's Quaternary geologists used to describe the break-through as a massive, single tap of Niagara -like force, but there is now evidence that it happened in several steps over a limited period, and along different local troughs and passages, with evidence for all three of ice marginal, supraglacial, or subglacial drainage at various times. It has been postulated that because

261-409: A body of water from 2 hectares (5 acres) to 8 hectares (20 acres). Pioneering animal ecologist Charles Elton regarded lakes as waterbodies of 40 hectares (99 acres) or more. The term lake is also used to describe a feature such as Lake Eyre , 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

348-500: 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 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

435-554: A dramatic erosion of sediments, peatlands and forests along its path. This led initially to a relatively rapid fall in the lake level over hundreds of years, which then continued at a slower pace. Another consequence of the lowering of the lake and isostatic uplift was that a north-south land bridge formed between Lake Vänern and the Ancylus Lake effectively making Lake Vänern a separate basin. The Ancylus Lake existed from approximately 9500 to 8000 years B.C. calibrated, during

522-402: 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 for a sustained period of time. They are often low in nutrients and mildly acidic, with bottom waters low in dissolved oxygen. Artificial lakes or anthropogenic lakes are large waterbodies created by human activity . They can be formed by

609-538: A higher perimeter to area ratio than other lake types. These form where sediment from a tributary blocks the main river. These form where sediment from the main river blocks a tributary, usually in the form of a levee . Lakes formed by other processes responsible for floodplain 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. A solution lake

696-510: 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 organisms . Consequently,

783-428: 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. Limestone caves often contain pools of standing water, which are known as underground lakes . Classic examples of solution lakes are abundant in

870-470: 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 1 hectare (2.5 acres) 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 superlinearly with lake area. Extraterrestrial lakes exist on

957-587: A massive inflow of salt-water. Shorelines of Ancylus Lake can be found today at c. 60 m above sea level in southern Finland and at c. 200 m near the northern Gulf of Bothnia . In 1887 Henrik Munthe was the first geologist to draw the conclusion that the Baltic Sea must once have been a freshwater lake. Munthe did so after finding fossils of the freshwater snail Ancylus fluviatilis in sediments. While these fossils were also found slightly before him by other geologists they thought they belonged to rivers, small former lakes or brackish water, failing thus to realize

SECTION 10

#1732772318949

1044-489: A natural outflow and lose water solely by evaporation or underground seepage, or both. These are termed endorheic lakes. Many lakes are artificial and are constructed for hydroelectric power generation, aesthetic purposes, recreational purposes, industrial use, agricultural use, or domestic water supply . 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 . Despite this uncertainty,

1131-403: 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

1218-535: 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 , forming the Sarez Lake . The Usoi Dam at

1305-466: A short but cold regression phase about 8,100 cal.BP, that lasted through to 8300 BP, and through to much greater salinity after 8,500 years BP). The greater salinity is a characteristic of a part of the evolving Littorina Sea called the Mastogloia Sea (about 8,000–7,500 BP), associated with a net 5 m (16 ft) rise in sea level between 8,200 and 7,700 cal. years BP. in which

1392-422: 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 , which is sometimes referred to as a chemocline . Lakes are informally classified and named according to the seasonal variation in their lake level and volume. Some of

1479-460: A well defined Baltic Ice Lake had come into existence. Beyond it only southern Sweden was potentially habitable. This area was referred to as an island in Greico-Roman literature as " Scandza " or less specifically as " Scandia ", which is generally assumed to be an inadvertent misrepresentation by ancient geographers. Southern Sweden was in early historic times, only reachable by water, or when

1566-443: Is sag ponds . Volcanic lakes are lakes that occupy either local depressions, e.g. craters and maars , or larger basins, e.g. calderas , 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

1653-403: 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 sinkholes that form part of the local karst topography . Where groundwater lies near the grounds surface, a sinkhole will be filled water as a solution lake. If such

1740-468: Is dammed behind an ice shelf that is attached to the coastline. They are mostly found in Antarctica. Fluvial (or riverine) lakes are lakes produced by running water. These lakes include plunge pool lakes , fluviatile dams and meander 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

1827-698: Is found between 12,650 BP and 11,200 BP. Non-tree pollens increased, especially from heliophytes . Thse pollen record shifts of northern Europe due to colder climate in the Younger Dryas occurred later than in southern Europe being between 12,600–12,750 cal. BP. The end of the Baltic Ice Lake marks also the transition in Europe to Pre-Boreal forest. There is a marked increase in Pine and birch pollen from 11,500 BP. After this open pine-birch forest covered

SECTION 20

#1732772318949

1914-452: Is made. An example is Crater Lake in Oregon , 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 lahars . The basin which is now Malheur Lake , Oregon was created when a lava flow dammed

2001-464: Is the type of diatoms found in the sediment. Some species require salt water, while others require fresh. Other invertebrates serve as marker species as well. Also, periods of maximum supply from melt water are marked by low organic carbon in the sediment. Higher carbon content, as occurred after the lake reached sea level, causes greater deposition of iron sulfide , which appears as a black varve . This has been demonstrated well in sediment cores from

2088-429: Is unknown but is estimated to be at least 2 million. Finland has 168,000 lakes of 500 square metres (5,400 sq ft) in area, or larger, of which 57,000 are large (10,000 square metres (110,000 sq ft) or larger). 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

2175-461: Is usually now regarded as one transgression event. Then followed the essentially stable salty Littorina Sea (about 7,500–4,000 years BP), and finally the less salty Baltic Sea (about 4,000 years BP–present day). The lake's existence was first postulated by Alfred Gabriel Nathorst in 1894. At about 22,000 years ago the Weichselian ice sheet was at its maximum and sea level was at

2262-650: The Boreal period . The lake became the Littorina Sea when rising sea levels broke through the Dana River forming the Great Belt. This transformation was gradual as salt-water had begun to enter the Ancylus Lake 8800 years B.P. The salt-water that entered the lake resulted in episodic brackish water pulses. The final end of the Ancylus Lake, however, came 7800–7200 year B.C. when Øresund was flooded causing

2349-568: The Holocene is close in time to the end of the ice lake. The timings, but not sequence of these events has changed in the literature with refinement of dating techniques. After the Baltic Ice Lake came the Yoldia Sea (about 11,700–10,700 years BP), which has been defined as starting when the Baltic Ice Lake reached sea level so saline water could ingress since Henrik Munthe 's work as summarised by him in 1910. In geological time scales this

2436-759: The Malheur River . Among all lake types, volcanic crater lakes most closely approximate a circular shape. 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

2523-554: The Proto-Indo-European root * leǵ- ('to leak, drain'). Cognates include Dutch laak ('lake, pond, ditch'), Middle Low German lāke ('water pooled in a riverbed, puddle') as in: de:Wolfslake , de:Butterlake , German Lache ('pool, puddle'), and Icelandic lækur ('slow flowing stream'). Also related are the English words leak and leach . There is considerable uncertainty about defining

2610-399: The density 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 and 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

2697-490: The Bølling–Allerød Interstadial when the ice lake formed, has data from multiple northern European studies that may be relevant. The algae Chara spp. are reportedly common in water environments at 13,500 BP with a steep fall by 13,300 and all but disappear by 12,400 BP. Pine and birch pollen is found from 13,200 to 12,500 BP. The Younger Dryas was predominantly tundra , with areas of taiga . Juniper pollen

Baltic Ice Lake - Misplaced Pages Continue

2784-597: The Earth by extraterrestrial objects (either meteorites or asteroids ). Examples of meteorite lakes are Lonar Lake in India, Lake El'gygytgyn in northeast Siberia, and the Pingualuit crater 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. In addition to

2871-571: The Lusatian Lake District, Germany. In India, Sudarshana Lake is a historical artificial lake located in the semi-arid region of Girnar, Gujarat, originally constructed during the reign of Chandragupta Maurya. See: List of notable artificial lakes in the United States Meteorite lakes, also known as crater lakes (not to be confused with volcanic crater lakes ), are created by catastrophic impacts with

2958-669: The Svea River canyon was the outlet of the Ancylus Lake gradually lost ground by the works of Sten Florin, Astrid Cleve and Curt Fredén . In 1927 Cleve who was already "an outcast of the geological community" commented in an opinion piece in Svenska Dagbladet on a proposal of making Svea River a national monument. She supported the idea of protecting the area but criticized the established interpretation of Munthe and von Post. Munthe replied in Dagens Nyheter and

3045-409: The area can be assumed to have been greater at times of the massive ice cap melting with earlier seas, but even now there is a marked gradient west to northeast. Seasonal ice cover also is relevant, and forms easier the lower the salt content of the water. Surface waters will tend to have lower salinity than deeper waters and high organic content with oxygenation is more likely closer to the connection to

3132-866: 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 is a landslide lake dating back to the last glaciation in Wales some 20000 years ago. Aeolian lakes are produced by wind action . These lakes are found mainly in arid 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 dunes ; and deflation basins formed by wind action under previously arid paleoenvironments. Moses Lake in Washington , United States,

3219-555: The borders of the Baltic Basin between 50,000 and 44,000 years ago. Several carbon-dated sites in Estonia indicate that human habitation of the shores of the Baltic Basin was present in the Boreal period , in the time window 11,200-10,200  years BP. No sites have been identified related directly to the Baltic Ice Lake. The earliest site so far dated is near Pärnu with a timing of about 100 years before 10,700  years BP on

3306-514: The continued isostatic uplift of Sweden, the outlets in central Sweden were severed. In turn this resulted in the lake tipping over a till substrate at what is now the Great Belt in Denmark. Being located no less than 10 m above sea level the lake began thus to drain to the sea through the Dana River between 9000 and 8900 years B.C. The formation of the Dana River is thought to have caused

3393-915: The courses of mature rivers, where a river channel has widened over a basin formed by eroded floodplains and wetlands . Some lakes are found in caverns underground . 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. Artificially controlled lakes are known as reservoirs , and are usually constructed for industrial or agricultural use, for hydroelectric power generation, for supplying domestic drinking water , for ecological or recreational purposes, or for other human activities. The word lake comes from Middle English lake ('lake, pond, waterway'), from Old English lacu ('pond, pool, stream'), from Proto-Germanic * lakō ('pond, ditch, slow moving stream'), from

3480-518: The creation of lakes by the disruption of preexisting drainage networks, it also creates within arid regions endorheic basins that contain salt lakes (also called saline lakes). They form where there is no natural outlet, a high evaporation rate and the drainage surface of the water table has a higher-than-normal salt content. Examples of these salt lakes include Great Salt Lake and the Dead Sea . Another type of tectonic lake caused by faulting

3567-476: The debate went over to a personal quarrel in two more newspaper letters in January 1928. Cleve outlined her ideas for Svea River and Ancylus Lake in detail in 1930 making an alternative and intricate theory involving tectonic movements. By 1946 she had changed mind as she then proposed an altogether different theory claiming the Svea River canyons and potholes formed by subglacial drainage and had nothing to do with

Baltic Ice Lake - Misplaced Pages Continue

3654-428: The depths of the Baltic Sea. The Baltic Ice Lake is one of a number of water stages that eventually resulted in the modern Baltic Sea, and is the first stage after the last ice age. The lake occupied part of the Baltic Basin that had seen many large lakes periodically form during the period between 64,000 to 16,000 years BP in the last ice age. The lake from the first evidence to the last has been dated historically in

3741-622: The difference between lakes and ponds , and neither term has an internationally accepted definition across scientific disciplines or political boundaries. For example, limnologists 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

3828-623: The edge of the glacier was at a line across southern Sweden to the northern shore of the Baltic countries. A connected body of water, the Ramsay Sea, stretched from the Danish islands region to the shores of Estonia . The gulfs of Bothnia and Finland were still glaciated, as well as nearly all of Sweden north of Scania . In the Allerød warm-period, rising land in the Denmark region ponded

3915-476: The end of the 19th century, with a flurry of consolidation work in the early 20th century. These processes happen at different rates, often over periods of tens to thousands of years. Timing of such events can have uncertainty and for example the onset of the Younger Dryas is apparently 180 years later in Northern Europe than Greenland. Melting of the ice cap provides a massive source of fresh water. This

4002-479: The end of the Allerød warming event at about 12,900 cal. years BP drained at an unknown location by between 10 and 20 m (33 and 66 ft) before rising again. Other authors have this draining event as sometime between 13,500 to 13,000 years ago. By its final drainage it had extended to much of the present southern Baltic shore line and extended east incorporating the area around the present Lake Ladoga . At

4089-536: The exception of criterion 3, the others have been accepted or elaborated upon by other hydrology publications. The majority of lakes on Earth are freshwater , 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 kilometres (1.2 sq mi) in surface area. The total number of lakes in Canada

4176-557: The existence of the lake. Geologists had until then subscribed to a simple scheme for the evolution of the Baltic Sea where small local ice-lakes were succeeded by the Yoldia Sea that then evolved directly to the Littorina Sea . The lake was named by Gerard De Geer in 1890 after the fossils. The lack of an obvious outlet of the lake led to intermittent debates involving not only Munthe and De Geer but also Ernst Antevs , Arvid Högbom , Axel Gavelin , N.O. Holst and H. Hedström. As

4263-422: The hypolimnion is a transition zone known as the metalimnion . 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

4350-523: The ice cap had extended southwards during the Younger Dryas in south-west Sweden, a factor in the break through at Mount Billingen was that rebound was delayed there. At the start of drainage into the sea here the land was just a bit more than 25 m (82 ft) above the local sea level, and the drainage was both along the ice margin on the east side of Billingen and subglacially near present Timmersdala where recent interpretations are consistent with an ice tunnel existing. Other drainage later took place on

4437-478: The ice retreated northward. These were about 40 m (130 ft) above the current sea level. The formation of the Baltic Ice Lake in the deepest part of today's Baltic Sea, at Landsort Deep which is 459 m (1,506 ft) below present sea level took place about 13,600 years ago, in the Bølling–Allerød Interstadial. The Baltic Ice Lake covered a large area by 13,000 BC between present southern Sweden , Lithuania and up to Estonia . By 12,000 years BP,

SECTION 50

#1732772318949

4524-907: The intentional damming of rivers and streams, rerouting of water to inundate a previously dry basin , or the deliberate filling of abandoned excavation pits by either precipitation runoff , ground water , or a combination of both. Artificial lakes may be used as storage reservoirs that provide drinking water for nearby settlements , to generate hydroelectricity , for flood management , for supplying agriculture or aquaculture , or to provide an aquatic sanctuary for parks and nature reserves . 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 ponds, and residual water bodies following river regulation. Same for

4611-471: The karst regions at the Dalmatian coast of Croatia and within large parts of Florida . A landslide lake is created by the blockage 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

4698-534: The lake level. Ancylus Lake Ancylus Lake is a name given by geologists to a large freshwater lake that existed in northern Europe approximately from 9500 to 8000 years BC being in effect one of various predecessors to the modern Baltic Sea . The Ancylus Lake replaced the Yoldia Sea after the latter had been severed from its saline intake across a seaway along the Central Swedish lowland , roughly between Gothenburg and Stockholm . The cutoff

4785-485: The lakes in the Baltic basin which may have egressed through a small channel in the Strait of Øresund or perhaps southern Sweden. The lake was higher than sea level (which itself was lower than the present-day sea level) by some tens of metres. Sediment at the bottom of the lake was organic–material-poor glacial clay. Emergence of the land and rebound then closed any channel through the Strait of Øresund. The lake rose and at

4872-657: 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 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 grabens and horsts that form elongate basins alternating with mountain ranges. Not only does this promote

4959-528: The layers of sediment at the bottom of a meromictic lake remain relatively undisturbed, which allows for the development of lacustrine deposits . 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

5046-560: 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 area, groundwater 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

5133-481: The mainland; lakes cut off from larger lakes by a bar; or lakes divided by the meeting of two spits. 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 have 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 are

5220-424: 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 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

5307-485: The moon Titan , 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 . 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

SECTION 60

#1732772318949

5394-415: The morphology of the lakes' physical characteristics or other factors. Also, different cultures and regions of the world have their own popular nomenclature. 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,

5481-406: 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,

5568-791: The names include: Lakes may be informally classified and named according to the general chemistry of their water mass. Using this classification method, the lake types include: 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 deposits that accumulated in them and any fossils that might be contained in these sediments. The paleoshorelines and sedimentary deposits of paleolakes provide evidence for prehistoric hydrological changes during

5655-531: The northeast side of Billingen. The flood through the Lảngen valley was over glacier ice. Currently accepted durations for the discharge range between about half a year to 1.5 years, but some have postulated decades. The peak discharge is therefore moderate for a outburst flood . Flow velocities for the first few months peaked at 10–12 m/s (22–27 mph), with a peak discharge rate of 200,000–400,000 m/s (7,100,000–14,100,000 cu ft/s). The ecology of

5742-556: The ocean by rivers . Lakes, as with other bodies of water , are part of the water cycle , the processes by which water moves around the Earth. Most lakes are freshwater and account for almost all the world's surface freshwater, but some are salt lakes with salinities even higher than that of seawater . Lakes vary significantly in surface area and volume of water. Lakes are typically larger and deeper than ponds , which are also water-filled basins on land, although there are no official definitions or scientific criteria distinguishing

5829-562: 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 and natural gas . Although of significantly less economic importance, strata deposited along the shore of paleolakes sometimes contain coal seams . Lakes have numerous features in addition to lake type, such as drainage basin (also known as catchment area), inflow and outflow, nutrient content, dissolved oxygen , pollutants , pH , and sedimentation . Changes in

5916-544: The outlet was lacking there were doubts on whether Lake Vänern had been part of the lake or not, and on the position of its outlet or whether an outlet actually existed considering the lake could have been at sea level. Lennart von Post discovered by accident a small canyon near Degerfors in 1923 which he thought could be the elusive outlet. This came with time to be known as Svea River. Von Post collaborated initially with Munthe to study Svea River but their collaboration fell apart by 1927 over personal issues. The idea that

6003-479: The peak of this high-water phase, most of Finland was under water, including present-day Helsinki at a depth of 115 m (377 ft); only southern Sweden was both free of ice and above the waterline. The Danish Islands were all connected west of the Strait of Øresund. Emergence of the land through rebound after the loss of ice cover then closed the channel through the Strait of Øresund. The lake rose until at about 11,620 cal. years BP it broke through as

6090-540: The range 16,000 to 10,500 years BP, but there is now a defined end point at 11,620 cal. years BP, with sea water entry shortly after, which will be used in this article. The period of the lakes well defined existence from a continuous core sedimentary record extends from the warming of the Bølling–Allerød Interstadial to the end of the period of cooling called the Younger Dryas . The beginning of

6177-461: The recent low of 120 m (390 ft) below present sea level. In the thousand year period from 16,000  years BP the edge of the retreating Weichselian glacier departed from the Lake Gardno end- moraines of Pomerania (in present-day northern Poland ) and reached the southern shore of the Baltic Sea where closed fresh-water pools formed in the southern Baltic region from melt water as

6264-468: The region and this is reflected in pollen levels much higher than in the Bølling–Allerød Interstadial. The distribution of species such as the fresh water crustacean Limnocalanus macrurus in high Swedish fresh water lakes has long been potentially explained by seeding when these lakes were part of the Baltic Ice Lake high stand or very close to it. Similarly layers of clay that contained cod fossils or marine diatoms were long recognised as being related to

6351-460: The sea shore of the Yoldia Sea, so is just before the occupiers were forced to retreat inland by Ancylus Lake expansion. The earliest stationary fishing equipment is dated to 9,000 cal BP so is well after the ice lake stage. At about 16,000  years BP the retreating ice had reached the southern shores of the present Baltic. Melt water formed extensive lacustrine systems still visible today in north Russia, Poland and Germany. By 14,600 years BP

6438-409: The sills are substantially above sea level. The release of fresh water from the glaciers depends on climate; the presence or absence of entrances to the ocean depends on land rise and oceanic water level; the latter is also affected by the amount of ice held in glaciers worldwide. Several methods are used to determine the quality (temperature, salinity, solids content) of ancient sea water. The main one

6525-404: 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 , 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

6612-456: The times that they existed. There are two types of paleolake: 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 piedmonts of many basins; and their sediments contain enormous quantities of geologic and paleontologic information concerning past environments. In addition,

6699-539: The transition from fresh water to sea water and later raised by sea floor rebound. The significance of the distribution of fresh and salt water species in working out the history of the Holocene Baltic lakes and seas was well understood by 1910. The Riadino-5 archaeological site on the lower Šešupė river in the Kaliningrad Oblast shows intraglacial human habitation with flint artefacts existed on

6786-641: The two. Lakes are also distinct from lagoons , which are generally shallow tidal pools dammed by sandbars or other material at coastal regions of oceans or large lakes. Most lakes are fed by springs , and both fed and drained by creeks and rivers , but some lakes are endorheic without any outflow, while volcanic lakes are filled directly by precipitation runoffs and do not have any inflow streams. Natural lakes are generally found in mountainous areas (i.e. alpine lakes ), dormant volcanic craters , rift zones and areas with ongoing glaciation . Other lakes are found in depressed landforms or along

6873-427: The water froze over. The area surrounding the ice lake was relatively barren and human interaction has not been proved but is not impossible. As the sediments deposited in the lake were relatively poor in organic matter it is likely that the area of the shore of the lake was less attractive as a food source compared to later bodies of water and did not attract settlements detected later in time by archaeologists. There

6960-467: 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 book proposes to define the term "lake" as a body of water with the following five characteristics: With

7047-528: The world seas, if one exists. The main factors relevant were the advance or recession of the Weichselian glaciation responsible for the Fenno-Scandian ice sheet and the isostatic sinking of the landforms due to the weight of ice or rebound when it melts (springing back, post-glacial rebound, glacial isostatic adjustment ), and this was known by geologists to be relevant to the Baltic area by

7134-404: Was a drainage event, at an unknown location, by 12,900 cal. years BP. at the latest. Around 11,620 cal. years BP, the ice lake discharged as an outburst flood through channels that opened near Billingen in central Sweden until it reached the raising world ocean level. There is evidence to back all the possibilities of ice marginal, supraglacial, or subglacial drainage. Peak discharge rate

7221-631: Was also the transition from the Younger Dryas to the Pre-Boreal . After the Yoldia Sea the Ancylus Lake formed and this existed from about 10,700 to 9,800 years BP. The Ancylus Lake was 13 to 15 m (43 to 49 ft) above later sea levels, and was first described by Munthe in 1887. This was followed by a transitional phase called the initial Littorina Sea with partial salt water ingression commencing 9,800 cal. years BP, with in Sweden

7308-544: Was associated with the formation of various glacial lakes and influenced sea levels worldwide, which have risen since 22,000 years ago about 120 m (390 ft). Locally salt water entered from the North Sea through straits when the sea level was high enough to allow reverse flow over the sill. When the straits are above sea level or close to sea level, fresh water will accumulate and a lake forms. Fresh water will accumulate to levels substantially higher than sea level when

7395-617: 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 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

7482-434: Was possibly up to 400,000 m/s (14,000,000 cu ft/s). The Yoldia Sea phase began shortly afterwards. Lake A lake is an often naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land . Lakes lie completely on land and are separate from the ocean , although they may be connected with

7569-500: Was the result of isostatic rise being faster than the concurrent post-glacial sea level rise . In the words of Svante Björck the Ancylus Lake "is perhaps the most enigmatic (and discussed) of the many Baltic stages". The lake's outlet and elevation relative to sea-level was for long time surrounded by controversy. It is now known that the lake was above sea level, included Lake Vänern , and drained westward through three outlets at Göta Älv , Uddevalla and Otteid . As result of

#948051