Ice-Covered Lakes Environment - Freezing of Lakes and the Evolution of their Ice Cover - page 256

Ice driven mechanical shoreline erosion and deformation has been often observed in
the Great Lakes of North America (Bolsenga 1988). The ice affects such constructions as
shoreline houses, boathouses and docks. Normally a stable ice cover protects the shore,
but when the shoreline ice is suf ciently thick, bottom scouring may take place and

moving ice may encroach the shore zone. Ice features forming in the nearshore areas
include the ice foot, a long continuous ridge of grounded ice, and ice ridges.
In very shallow zones, freezing may reach the bottom. In spring the buoyancy of ice
may raise the bottom material with ice to surface and the mass appears as drifting ' mud

fl (Helaakoski 1912). This mechanism is also able to spread vegetation in the lake

basin. Melting of permafrost results in subsurface shore erosion and cutting vegetation
fl

oats '

floats from the shore zone (Parsekian et al. 2011).

8.2.4 Sports on Lake Ice

Lake ice with the necessary bearing capacity has provided an excellent platform for winter
sports. Skiing on lake has its roots in pre-historical times in northern Europe, and it
developed sport as the side product during the 1800s. Although serious sports has moved to
forests and mountains, snow-covered lake ice widely attracts recreational skiing
community.
Skating has also long history, at least from the Medieval Times. In Central Europe it
has been very popular in cold winters when the ice has the necessary bearing capacity.
Further north, where winters are colder and longer snow accumulation brings often
problems, but many communities keep a skating route open on the natural lake ice. In
good skating winters, large areas of lakes are covered by bare ice and long distance free
skating is possible (Fig. 8.9 ).

Fig. 8.9 Skating on Lake
Vesij ä rvi ice, southern Finland.
Photograph by Mr. Seppo
Leinonen, printed with
permission