Origin of natural lakes

Ipperwash Beach, Lake Huron, Ontario, Canada

Geologically speaking, most lakes are young. The natural results of erosion will tend to wear away one of the basin sides containing the lake, such as the shores of Lake Baikal in Russia which is estimated to be 25 – 30 million years old. There are a number of natural processes that can form lakes. A recent tectonic uplift of a mountain range can create bowl-shaped depressions that accumulate water and form lakes. The advance and retreat of glaciers can scrape depressions in the surface where lakes accumulate; such lakes are common in Scandinavia, Patagonia, Siberia and Canada. Lakes can also form by means of landslides or by glacial blockages. An example of

the latter occurred during the last ice age in the US state of Washington, when a huge lake formed behind a glacial flow; when the ice retreated, the result was an immense flood that created the Dry F

alls at Sun Lakes, Washington.

Salt crystals, on the shore of Lake Urmia, Iran

Salt lakes (also called saline lakes) can form where there is no natural outlet or where the water evaporates rapidly, and the drainage surface of the water table has a higher than normal salt content. Examples of salt lakes include Great Salt Lake, the Caspian Sea, the Aral Sea and the Dead Sea.

Small, crescent-shaped lakes called oxbow lakes can form in river valleys as the result of meandering. The slow-moving river forms a sinuous shape as the outer side of bends are eroded away more rapidly than the inner side. Eventually a horseshoe bend is formed and the river cuts through the narrow neck. This new passage then forms the main passage for the river and the ends of the bend become silted up, thus forming a bow-shaped lake.

Lake Vostok is a subglacial lake in Antarctica, possibly the largest in the world. The pressure from ice and the internal chemical composition means that if the lake were drilled into, it may result in a fissure which would spray in a similar fashion to a geyser.

Some lakes, such as Lake Baikal and Lake Tanganyika lie along continental rift zones, and are created by the crust's subsidence as two plates are pulled apart. These lakes are the oldest and deepest in the world, and may be destined over millions of years to become oceans. The Red Sea is thought to have originated as a rift valley lake.

Crater Lake in Oregon, USA is a lake located within the caldera of Mount Mazama. The caldera was created in a massive volcanic eruption that lead to the subsidence of Mount Mazama around 4860 BC. Since that time, all eruptions on Mazama have been confined to the caldera.

Some lakes, such as Lake Jackson, USA come into existence as a result of sinkhole activity.

From Wikipedia