 With the rare exception of lakes near the edges of the permanent icecaps in Greenland and Antarctica, amictic lakes do experience melting around the lake's perimeter during summer, resulting in a "moat" of water surrounding a thick pan of ice that remains in the centre of the lake.This melting occurs as a result of heat absorbed by water and sediments below the ice, particularly in the shallow-water areas, when snow does not cover the ice, and also by heat flow and meltwater runoff from the surrounding land.Mixing below the ice occurs due to density currents generated by heat from direct solar radiation and from meltwater runoff which may differ in density from the lake water due to both temperature and suspended sediment content, depending on its source and flow path.