Freezing of Lakes - Freezing of Lakes and the Evolution of their Ice Cover - page 15

Example 2.1. The Baltic Sea has a dynamic history since the retreat of the Fennoscandian

ice sheet, beginning 15,000 years ago, due to the positive fresh water balance and rebound
of the ground from the pressure of the ice sheet (see Lepp ranta and Myrberg 2009). First,

the basin was an epiglacial lake (the Baltic Ice Lake), then a brackish sea (the Yoldia Sea,
connected to Atlantic), and again an epiglacial lake (Ancylus Lake, Fig. 2.3 ). About
8,000 years ago Ancylus Lake turned into a brackish marine basin, which has developed
to the present Baltic Sea. The land uplift is still in progress in the northern Baltic Sea, and
after 1,000 years the northern basin, the Bay of Bothnia, will be isolated from the oceanic
connection and become the largest lake in Europe. The presently largest lake of Europe,
Lake Ladoga, was part of the Baltic Ice Lake but became isolated in the Yoldia Sea phase.
The physical classi

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cation of the lake basins concerns their size and shape. A simple
approach is to consider the magnitudes of the geometric size, both horizontal and vertical

Fig. 2.3 Ancylus Lake. Also shown are the largest lake of Europe, the Lake Ladoga, which
separated at the formation of the Yoldia Sea about 10,000 years ago, and the Bay of Bothnia, the
largest lake in Europe after 1,000 years. The contour inside the lake shows the present Baltic Sea.
Modified from Lepp ä ranta and Myrberg (2009)