The coastal plain of northwest Canada and adjacent Alaska is a unique lake region. This area is one of extensive permafrost in a low-relief environment. Parts of this region were glaciated during the Pleistocene Epoch, but much was not. The Arctic lowlands are home to tens and perhaps hundreds of thousands of shallow lakes. Some of these are underlain by peat, while others lie on glacial deposits or marine sediments derived from prior high sea levels. In the present era of rising temperatures many lakes are being formed and subsequently drained by thawing of permanently frozen ground. When ice-rich sediments begin to thaw they may settle as water melts and is expelled from the sediments. Areas of shallow standing water form, and because in the brief warm season this water absorbs and stores more heat than surrounding vegetated areas the thawing and settling of sediments beneath is accelerated. This process is called thermokarst, and results in the formation of lakes. At the same time many lakes are being drained as the thawing and settling of sediments continues.
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