Ancient Lake
Encyclopedia
An ancient lake is a lake
that carried water uninterruptedly for more than one million years. The vast majority of lakes, including very large ones such as the Great Lakes
, are of much more recent origin. The short life of most of lakes is due to continued sedimentation
by their tributaries, which typically leads to complete siltation
after several thousand years.
In contrast, the longevity of ancient lakes can mostly be attributed to geological
factors, such as plate tectonics
, which can counter siltation
.
, ancient lakes form isolated 'water islands' in the midst of 'oceans of land'. An ancient lake's long lifespan may give rise to the evolution of endemic species (that are particular to their location). In comparison to the oceans, evolutionary biology examines the circumstances that conditioned the evolution of new species. In Lake Tanganyika
, for instance, scientists study the adaptive radiation
of cichlids, while in Lake Ohrid
, research focuses on endemic mollusca
.
Lake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...
that carried water uninterruptedly for more than one million years. The vast majority of lakes, including very large ones such as the Great Lakes
Great Lakes
The Great Lakes are a collection of freshwater lakes located in northeastern North America, on the Canada – United States border. Consisting of Lakes Superior, Michigan, Huron, Erie, and Ontario, they form the largest group of freshwater lakes on Earth by total surface, coming in second by volume...
, are of much more recent origin. The short life of most of lakes is due to continued sedimentation
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
by their tributaries, which typically leads to complete siltation
Silt
Silt is granular material of a size somewhere between sand and clay whose mineral origin is quartz and feldspar. Silt may occur as a soil or as suspended sediment in a surface water body...
after several thousand years.
In contrast, the longevity of ancient lakes can mostly be attributed to geological
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
factors, such as plate tectonics
Plate tectonics
Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...
, which can counter siltation
Silt
Silt is granular material of a size somewhere between sand and clay whose mineral origin is quartz and feldspar. Silt may occur as a soil or as suspended sediment in a surface water body...
.
Importance of ancient lakes' ecospheres
With respect to evolutionary biology, ancient lakes serve as natural isolation laboratories. For example, in the Galápagos IslandsGalápagos Islands
The Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, west of continental Ecuador, of which they are a part.The Galápagos Islands and its surrounding waters form an Ecuadorian province, a national park, and a...
, ancient lakes form isolated 'water islands' in the midst of 'oceans of land'. An ancient lake's long lifespan may give rise to the evolution of endemic species (that are particular to their location). In comparison to the oceans, evolutionary biology examines the circumstances that conditioned the evolution of new species. In Lake Tanganyika
Lake Tanganyika
Lake Tanganyika is an African Great Lake. It is estimated to be the second largest freshwater lake in the world by volume, and the second deepest, after Lake Baikal in Siberia; it is also the world's longest freshwater lake...
, for instance, scientists study the adaptive radiation
Adaptive radiation
In evolutionary biology, adaptive radiation is the evolution of ecological and phenotypic diversity within a rapidly multiplying lineage. Starting with a recent single ancestor, this process results in the speciation and phenotypic adaptation of an array of species exhibiting different...
of cichlids, while in Lake Ohrid
Lake Ohrid
Lake Ohrid straddles the mountainous border between the southwestern Macedonia and eastern Albania. It is one of Europe's deepest and oldest lakes, preserving a unique aquatic ecosystem with more than 200 endemic species that is of worldwide importance...
, research focuses on endemic mollusca
Mollusca
The Mollusca , common name molluscs or mollusksSpelled mollusks in the USA, see reasons given in Rosenberg's ; for the spelling mollusc see the reasons given by , is a large phylum of invertebrate animals. There are around 85,000 recognized extant species of molluscs. Mollusca is the largest...
.
Selected ancient lakes
- Lake BaikalLake BaikalLake Baikal is the world's oldest at 30 million years old and deepest lake with an average depth of 744.4 metres.Located in the south of the Russian region of Siberia, between Irkutsk Oblast to the northwest and the Buryat Republic to the southeast, it is the most voluminous freshwater lake in the...
(SiberiaSiberiaSiberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...
) - Lake ZaysanLake ZaysanLake Zaysan is a freshwater lake, ca. 1,810 km² , in eastern Kazakhstan, in a hollow between the Altai and Tarbagatai Mountains. It is the largest lake in the East Kazakhstan Province....
(KazakhstanKazakhstanKazakhstan , officially the Republic of Kazakhstan, is a transcontinental country in Central Asia and Eastern Europe. Ranked as the ninth largest country in the world, it is also the world's largest landlocked country; its territory of is greater than Western Europe...
) - Lake BiwaLake Biwais the largest freshwater lake in Japan, located in Shiga Prefecture , northeast of the former capital city of Kyoto. Because of its proximity to the ancient capital, references to Lake Biwa appear frequently in Japanese literature, particularly in poetry and in historical accounts of battles.-...
(JapanJapanJapan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
) - Lake OhridLake OhridLake Ohrid straddles the mountainous border between the southwestern Macedonia and eastern Albania. It is one of Europe's deepest and oldest lakes, preserving a unique aquatic ecosystem with more than 200 endemic species that is of worldwide importance...
(BalkansBalkansThe Balkans is a geopolitical and cultural region of southeastern Europe...
) - Lake TanganyikaLake TanganyikaLake Tanganyika is an African Great Lake. It is estimated to be the second largest freshwater lake in the world by volume, and the second deepest, after Lake Baikal in Siberia; it is also the world's longest freshwater lake...
(East AfricaEast AfricaEast Africa or Eastern Africa is the easterly region of the African continent, variably defined by geography or geopolitics. In the UN scheme of geographic regions, 19 territories constitute Eastern Africa:...
) - Lake MalawiLake MalawiLake Malawi , is an African Great Lake and the southernmost lake in the Great Rift Valley system of East Africa. This lake, the third largest in Africa and the eighth largest lake in the world, is located between Malawi, Mozambique, and Tanzania...
(East AfricaEast AfricaEast Africa or Eastern Africa is the easterly region of the African continent, variably defined by geography or geopolitics. In the UN scheme of geographic regions, 19 territories constitute Eastern Africa:...
) - Lake TiticacaLake TiticacaLake Titicaca is a lake located on the border of Peru and Bolivia. It sits 3,811 m above sea level, making it the highest commercially navigable lake in the world...
(South AmericaSouth AmericaSouth America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
) - Lake LanaoLake LanaoLake Lanao is a large lake in the Philippines, located in Lanao del Sur province in the country's southern island of Mindanao. With a surface area of 340 km²...
(PhilippinesPhilippinesThe Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
)