What Is Lake? How Is It Formed?
Lake is an island expanse of water more or less permanently occupying a large hollow in the Earth’s surface, basically a water body surrounded by land. However, some lakes – for example, Lake Eyre in South Australia may shrink dramatically or disappear completely during a dry season.
Lakes may be fresh water or saline (salty) like the Great Salt Lake, Utah, USA and the Dead Sea, Israel. They may also be artificial, such as Kariba Lake, formed behind the Kariba Dam in southern Africa. There is considerable uncertainty about defining the difference between lakes and ponds, and no current internationally accepted definition of either term across scientific disciplines or political boundaries exists.
In lake ecology the environment of a lake is referred to as lacustrine. Large lakes are occasionally referred to as “inland seas,” and small seas are occasionally referred to as lakes, such as Lake Maracaibo, which is actually a bay. Larger lakes often invert the word order, as in the names of each of the Great Lakes, in North America.
Lakes have bowl-shaped depression in the earth that is filled with water. This depression is referred to as Lake Basins. There are many ways these basins can be formed. let’s discover a few.
First, Tectonic plate. Many basins are formed due to the movement of tectonic plates that changes the Earth’s Crust. When the Crust breaks, deep cracks, called Faults, may form. These faults make the natural basins and when filled with a nearby stream of rainwater to form a Lake.
Second, Glaciers. This is common with lakes formed in the northern hemisphere. During the last ice age, most of the land in the Northern Hemisphere was covered with Glaciers. The huge masses of ice carved out great pits and scrubbed the land as they moved along slowly. When the glaciers melted, water filled those depressions, forming lakes.
Third, Volcanoes. After a volcano becomes inactive, its crater may fill with rain or melted snow. Sometimes the top of a volcano is blown off or collapses during an eruption, leaving a depression called a caldera. It, too, may fill with rainwater and become a lake.
Fourth, Asteroids. This may be the least common way of forming lakes on earth. Many asteroids burn up during their entry in the earth’s atmosphere, nut some do complete the journey and end up landing on the surface. The asteroids hit earth at extreme speed and create basins which later get filled up by nearby streams or rainwater.
Fifth, Humans. People make lakes by digging basins or by damming rivers or springs. These artificial lakes can become reservoirs, storing water for irrigation, hygiene, and industrial use. Artificial lakes also provide recreational use for boating, swimming, or fishing.
Once formed, lakes do not stay the same. Like people, they go through different life stages—youth, maturity, old age, and death. All lakes, even the largest, slowly disappear as their basins fill with sediment and plant material. The natural aging of a lake happens very slowly, over the course of hundreds and even thousands of years. But with human influence, it can take only decades.