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Ancient lake

Lakes formed before the last glacial maximum From Wikipedia, the free encyclopedia

The term ancient lake has two different meanings. For biologists, an ancient lake has consistently carried water for a geologically significant amount of time, typically more than one million years. For paleontologists, an ancient lake is paleo-evidence of a lake, a lake bed evident in geology.[1]

Lake Zaysan in Kazakhstan is one of the oldest lakes in the world.

Biologically ancient lakes existed before the latest glacial maximum.[2] Due to the prolonged life of ancient lakes, they serve as models for isolated evolutionary traits and speciation. Lake Baikal is considered the oldest, as clear evidence shows that it is 25–30 million years old.[3][4] Most of the world's bodies of water are less than 18,000 years old.[5]

Paleo-lakes

Modern lakes have many complex processes and interactions making their classification difficult. Ancient lakes are relatively simple.[6]

Stratigraphy

Ancient lakes show three characteristic geological traits: indistinctly sequenced layers with evidence of fresh water biology called fluvial-lacustrine, distinct cyclic layers with mixed salt and saline biota called fluctuating profundal (deep water lakes of varible depth), and high-frequency cyclic layering with primary salt water biologic evidence called evaporative traits. These traits have been traced to a balance between tectonic activity increasing sediment and climate changes altering the water fill rates. For overfilled lakes, high inflow keeps the lake full with minimal level variations, leading to fluvial-lacustrine stratigraphy. Balance filled lakes fluctuate as the balance shifts, with these shifts recorded in the sediments. Underfilled lakes have no outflow and alternate between flooding and desiccation, leading to the evaporative stratigraphy.[6]

Biology

Biologists are interested in long-lived lakes as possible evolutionary reservoirs. Such lakes have high biodiversity and more species specific to the lake. However lakes with long histories may not be stable habitats due to interaction with rivers and other bodies of water as well as geological or climatic changes that change the character of the lake.[1] All major ancient lakes have seen significant surface warming and most have contaminants introduced by human activity, creating an urgency to their study before further alterations.[7]

For example, Lake Baikal in Russia is an ancient lake 25–30 million years old located in the Baikal Rift Zone. This is compared to the North American Great Lakes, formed by glacial scouring and the pooling of meltwater, which are 14,000 years old.[citation needed]

Importance to evolution

Ancient lakes allow scientists to study the mechanisms of environmental changes over glacial-interglacial timescales. Ultra-rapid speciation has been documented in some ancient lakes, but no mechanism specific to such lakes has been uncovered.[1]

List of ancient lakes

These are the ancient lakes in the world that have existed for more than 1 million years, excluding the many subglacial lakes whose age is yet to be determined.[5]

More information Name, Origin ...
Name Origin Type Area Volume Depth max Depth average Countries Notes
km2sq mi km3cu mi mft mft
Lake Pingualuk meteor impact fresh, permanent, crater 83.1   267876   Canada
Lake Tahoe tectonic fresh, permanent 499193 15637 5051,657 3131,027 United States
Lake Bosumtwi meteor impact soda, permanent, crater 4919 2.240.54 81266 45148 Ghana
Lake Tazawa volcanic caldera 25.759.94 7.21.7 423.41,389 280.0918.6 Japan Two lava domes on the caldera floor formed between 1.6 and 1.8 Ma.[8]
Lake Lanao volcanic fresh, permanent 375145   112367 60.3198 Philippines
Lake Titicaca tectonic 8,3723,232 893214 281922 107351 Bolivia, Peru
Lake Prespa 259100 4.81.2 54177 18.761 Albania, Greece, North Macedonia
Lake Ohrid 358.18138.29 53.6312.87 286.7941 163.71537.1 Albania North Macedonia
Lake Malawi 29,60011,400 8,4002,000 7052,313 292958 Malawi, Mozambique, Tanzania
Lake Hovsgol 2,7701,070 38191 267876 138453 Mongolia
Kati Thanda–Lake Eyre saline, intermittent, endorheic 9,6903,740 30.17.2 620 39.8 Australia
Lake Tanganyika fresh, permanent 32,00012,000 17,8004,300 1,4714,826 5721,877 Burundi, Congo, Tanzania, Zambia
Karakul meteor impact saline, permanent, endorheic, crater 380150 79.819.1 230750 210690 Tajikistan
Caspian Sea tectonic brackish, permanent, endorheic 374,000144,000 78,20018,800 1,0253,363 182597 Azerbaijan, Iran, Kazakhstan, Russia, Turkmenistan
Aral Sea saline, permanent 64,50024,900 625150 67220 1652 Kazakhstan, Uzbekistan Formerly the fourth largest lake in the world with an area of 68,000 km2 (26,300 sq mi). By 1997, it had shrunk to 10% of its original size due to water that was diverted in the Soviet Era. It is now split into 4 smaller lakes. As of 2023, the Aral Sea has become mostly desert.
Lake Biwa fresh, permanent 674260 27.56.6 104341 41135 Japan
Lake Tule 5320 409.6     United States This lake has become intermittent in recent years.
Lake Maracaibo saline, permanent, coastal bay 13,0105,020 28067 60200 25.985 Venezuela Historically it was an ancient lake. Now, it is a large tidal bay/inlet rather than a lake in the traditional sense. It is saline and directly connected to the Caribbean Sea, leading many to consider it a large lagoon or bay.
Lake Baikal fresh, permanent 31,50012,200 23,0005,500 1,7415,712 7402,430 Russia
Issyk-Kul saline, permanent 6,2362,408 1,738417 6682,192 270890 Kyrgyzstan
Lake Vostok subglacial fresh, permanent, subglacial 12,5004,800 5,4001,300 5101,670 4321,417 Antarctica
Lake Zaysan tectonic fresh, permanent 5,5102,130 5313 1033 516 Kazakhstan The construction of the Bukhtarma dam inundated the lake, thus, in some sources, the lake is considered a reservoir.[9]
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