Peipsi Lake in Estonia/Russia
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PALEOLAKES Reginald W. Herschy Hydrology Consultant, Reading, UK
Introduction All lakes are subject to a variety of extrinsic and intrinsic forcing variables that regulate the subsequent history of the lake. This includes age, climate, catchment, bedrock composition, tectonic and volcanic activity, vegetation, aquatic biota, and human activities. Strictly it is the history of change in these variables and the paleolimnological records of very old or ancient lakes that eventually lead us to the age of the lake. Paleolimnological records found in three distinct types of archive Water Lake water itself and its contents have finite residence times, the time required for the average molecule of water to cycle through the system. In lakes with long residence time measured in say hundreds to thousands of years, the water itself may provide important paleolimnological clues to lake history. Geomorphology The geomorphology of the lake basin in its shoreline and shape characteristic features can persist for many thousands of years long after the lake has gone. In this respect, a lake basin evolution is a more useful concept than the static one of lake origin. It is therefore an essential element in the design of a paleolimnological study.
Sediments Sediments provide the most durable feature since they may persist long after the lake itself, or its geomorphology ceased to exist. Content archives in paleolimnological are the physical sedimentary inputs to the lake’s record. These include terrigenous, chemical, and biogenic sediments; cosmogenic and volcanogenic particles; and fossils that originate outside the lake, like pollen, or in the lake, like fish, aerosols, and water-borne pollutants. Formation and history of lakes The formation and history of lakes has intrigued earth scientists for over a century; Hutchinson (1957) recognized 11 major categories of lake origins and since then advances have been made in understanding basin evolution using radiometric dating techniques, seismic stratigraphy, and lake drilling. The following lake classification (after Cohen, 2003) incorporates major elements of Hutchinson’s scheme: Basin closure
Temporal duration (years)
1. Glacial 2. Tectonic 3. Fluvial 4. Coastal 5. Volcanic 6. Wind 7. Solution 8. Landslide 9. Meteorite 10. Artificial
104–105 105107 104 104 104–107 104 104–107 103 105–107 103
L. Bengtsson, R.W. Herschy, R.W. Fairbridge (eds.), Encyclopedia of Lakes and Reservoirs, DOI 10.1007/978-1-4020-4410-6, # Springer Science+Business Media B.V. 2012
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PALEOLIMNOLOGY
Paleolakes, Table 1 Ancient lakes (selection) Lake name
Country
Age (million years)
Aral Sea Baikal (Ozero Baykal) Biwa (Biwa-ko) Bosumtwi (Bosomtwe) Caspian Sea
Kazakhstan, Uzbekistan Russian Federation
2–20 Greater than 20
Japan Ghana
2–20 1–2
Azerbaijan, Iran Kazakhstan, Russian Federation, Turkmenistan Crater (2) Canada Eyre Australia Hovsgol (Khuvsgul) Mongolia Issyk-Kul (Isyk-Kul) Kyrgyzstan Lanao Malawi (Nyasa, Niassa) Maracaibo Ohrid Pingualuk Prespa Taho Tanganyika Titicaca (Lago Ti
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