The Lakes Portal
A portal dedicated to Lakes
Introduction
A lake is a naturally occurring, relatively large and fixed body of water on 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 the ocean by rivers, such as Lake Ontario. 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.
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 the two. Lakes are also distinct from lagoons, which are shallow tidal pools dammed by sandbars 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 the courses of mature rivers, where a river channel has widened over a basin formed by eroded floodplains and wetlands. 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. (Full article...)
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Lake Manly is a pluvial lake in Death Valley, California. It forms occasionally in Badwater Basin after heavy rainfall, but at its maximum extent during the so-called "Blackwelder stand," ending approximately 120,000 years before present, the lake covered much of Death Valley with a surface area of 1,600 square kilometres (620 sq mi). Water levels varied through its history, and the chronology is further complicated by active tectonic processes that have modified the elevations of the various shorelines of Lake Manly; during the Blackwelder stage they reached 47–90 metres (154–295 ft) above sea level. The lake received water mainly from the Amargosa River and at various points from the Mojave River and Owens River. The lake and its substantial catchment favoured the spread of a number of aquatic species, including some lizards, pupfish and springsnails. The lake probably supported a substantial ecosystem, and a number of diatoms developed there.
In Death Valley, lakes existed during different times in the geological past. After some poorly defined lake stages during the Miocene, Pliocene and early Pleistocene, the first large lake stage occurred about 185,000–128,000 years ago during the Tahoe glacial stage and formed the Blackwelder shorelines. This lake was the largest known extent of Lake Manly; theories that the lake merged with Lake Mojave farther south or even overflowed into the Colorado River close to Ludlow and across several other basins are, however, questionable. After the drying of this lake a later lake stage occurred 35,000–10,000 years ago during the Tioga/Wisconsin glaciation; this lake was smaller than the Blackwelder lake. During the Holocene, the lake disappeared; today only ephemeral lakes occur in Death Valley during strong floods.
This lake is one among many major lakes that formed in the Great Basin, the best researched of which are Lake Lahontan and Lake Bonneville. Decreasing temperatures and thus decreased evaporation rates as well as increased precipitation rates during the ice ages were responsible for the formation of these lake systems. Lake Manly collected the overflow from a number of lakes including Lake Tecopa, Mono Lake, Owens Lake, Searles Lake, Lake Panamint, Lake Mojave, Lake Dumont and Lake Manix. Not all of them existed or drained into Lake Manly simultaneously. (Full article...)General topics
Lake zones |
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Lake stratification |
Lake types |
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External media
- World Lake Database. International Lake Environment Committee Foundation. – provides a searchable database
- Global Lakes and Wetlands Database. World Wide Fund for Nature. – available for free download
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