Lakes are natural reservoirs formed as a result of water filling with depressions of land.
The reasons for the formation of these depressions and ways of filling them with water can be different, so there are several types of lakes.
Most of the large lakes on our planetAppeared as a result of tectonic processes in the earth's crust. As a result of the movement of slabs and earthquakes, cracks in the earth's crust and its deflections are formed. In these depressions water accumulates. For example, Onega Lake is located in a trough, and Lake Baikal is in a huge tectonic fissure.
Volcanic lakes are usually formed in cratersExtinct volcanoes. There are many such lakes in regions with high volcanic activity - in Kamchatka, in Japan. Volcanic lakes are also called lakes, which are formed in places where frozen lava, erupting from the volcano, blocks the river bed.
In the northern regions of the earth there are many glacial lakes. Their basins were formed as a result of the movement of glaciers, which pushed the upper soft layer of the earth and left after their departure a depression in the relief. In the mountains of the lake also arise due to glaciers, which, melting, leave after themselves moraine - a mixture of sand, stones, earth. It can block the mountain river, as a result of which a lake is formed. Mountain lakes are also formed as a result of landslides, when stones block the river bed.
In those areas where the crust is composed of gypsum,Dolomites and limestones, water can erode the rock, resulting in empty spaces under the ground - karst caves that can be filled with water. So there is a large part of underground lakes.
In areas of permafrost, the soil can sink in summer thawing, resulting in the formation of small lakes.
Some lakes form near the seaCoast, when the sand spit separates the shallow water from the sea, such lakes are called lagoons. If a sand spit separates a section of the river, a lake is also formed, but it is called an estuary.
Sometimes the bed of the river is too crooked, but gradually it is straightened, and the curvilinear part remains away from the riverbed, that is, a lake called the old man appears.