A lake is an inland body of relatively motionless water that usually has a river or stream feeding into or draining out of it.
Lakes contain about 90% of all the surface water found on Earth (not including oceans). Lakes form when water finds its way into a basin. In order to continue existing, lakes must have a continual source of new water, otherwise they will eventually dry up.
Most lakes contain fresh water. However, in some cases, the water found in a lake can become salty, just like the ocean. This happens when a lake does not have a stream, either above ground or underground, draining water away from it. As water enters a lake, it carries minerals with it. As this water dissolves, it leaves the minerals behind.
FACTS ON LAKES
Lakes differ to lagoons and estuaries due to the fact they are not connected to the ocean. A lake is also larger and deeper than other inland water bodies such as ponds.
The study of inland water bodies and ecosystems is called Limnology.
A lake usually contains freshwater but some can be saltwater.
What’s the difference between a lake and a pond?
First, lakes are usually much deeper and wider than ponds. The water at the bottom is colder than the water at the top during the summer. In ponds, the water temperature near the top of the pond is about the same as the water temperature at the bottom of the pond. Plants grow prolifically in ponds. In lakes, they usually grow near the edges, but not in the middle.
How do lakes and ponds develop?
Lakes develop in many ways. As ancient glaciers slid down mountainslides, they sometimes caused huge piles of rocks to pile up. Lakes formed behind these rock piles as rain water collected. Volcanoes can also form lakes. Lava combining with cold water can cause huge explosions, leaving craters in the earth where a lake forms. Forest fires can also cause lakes. A marsh is a wet area filled with plants. As a forest fire rages through an area, it kills all the marsh plants, creating an open area for a lake.
Are lakes polluted?
Some lakes, especially those in mountain ranges, are quite clean. Others are very polluted. Pollution from fertilizers and soaps is a major problem. These fertilizers contain phosphates, which cause algae growth. When algae grow too much in lakes, they crowd out other plant life and animals.