How are basins formed?
A basin is a depression in Earth or a dip that is lower than the rest of the surrounding land. Basins are shaped like bowls with sides higher than the bottom.
Know how they are formed, where they are formed and the factors necessary for their formation.
A drainage basin is any area of land where the precipitation collects and drains off into a common outlet like a river, bay or any other water body.
Some of the basins are filled with water while others may be empty. They can take thousands of years to form while forces like earthquakes can cause a basin formation overnight.
Types of Basins: How are they formed?
River Drainage basins:
These basins are formed in an area drained by a river and all of its tributaries. The river basin may be made of various watersheds.
Watersheds are small versions of river basins. Each stream and tributary has its own watershed that drains into a larger stream or wetland.
The streams and ponds and lakes are a part of the river basin.
The water in the drainage basin flows downhill towards a bigger one. A network of watersheds makes up the entire river basin.
For example: The Mississippi river has six major watersheds- Missouri, Upper Mississippi, Ohio, Tennessee, Lower Mississippi and Arkansas Red White rivers.
The Amazon River and all of its tributaries drain an area more than 7 million square kilometres.
These basins are formed through tectonic activity. It means the movement of the large parts of Earth's crust cause the formation of structural basins. The volcanic eruptions and earthquakes occur due to tectonic movement only.
The natural process of weathering and erosion also contribute to the formation of structural basins.
While the tectonic plates shift, the rocks and other material on the floor are forced downwards while the sides of the basin are pulled upwards. This process repeats over many decades and a structural basin of the shape of a bowl is formed.
Some of such basins may be endorheic basins which do not have enough water in them to show at the surface but have an internal drainage system.
A lake basin is another type of structural basin. Lake basins often form in valleys blocked by rocks or other debris left by a landslide, lava flow, or glacier.
These are the largest depressions on Earth. Edges of the continents, called the continental shelves from the sides of ocean basins.
These are caused by seafloor subduction are the tectonic activity that can shape the basins.