Classification of lake basins and lacustrine deposits of Estonia
Aasta | 1990 |
---|---|
Raamat | Paleolimnology and the Reconstruction of Ancient Environments |
Toimetaja(d) | Davis R. B. |
Kirjastus | Kluwe Academic Publishers |
Leheküljed | 209-220 |
Tüüp | artikkel kogumikus |
Eesti autor | |
Keel | inglise |
Id | 17897 |
Abstrakt
Based on extensive data from a long-term investigation, a new genetic classification of lake basins is proposed for Estonia. Eight lake groups are distinguished, tectonic-denudation, glacial, chemical, fluvial, coastal (neotectonic), telmatogenic, cosmogenic and artificial, containing 13 subgroups and 19 basin types. Also proposed is a new lithological classification of Estonia's organic and calcareous lake sediments, based on analyses of more than 2000 sediment samples from 90 contemporary and 50 late-glacial (extinct) lakes. Of the ca. 1150 Estonian lake basins that formed on mineral substrate, the two largest basins are of preglacial, tectonic-denudation origin, later modified by glaciers. Eight hundred lakes are of glacial origin, and 300 of other origins in the Holocene. In addition, ca 20000 bog pools formed on peat in the Holocene. Only minerogenous sedimentation occurred in the lakes in the late-glacial period. After that, organic (gyttjas) and/or calcareous sediments have formed. Azonal factors have been largely responsible for the wide variation in Estonia's lacustrine deposits.