A geographical basin is a bowl shaped depression or dip in the Earth’s surface, either oval or circular in shape. Some basins are empty while others contain water, and some are formed nearly instantaneously while others take thousands of years to form.
There are three major types of basins: river drainage basins, structural basins and ocean basins.
A river drainage basin is an area where rivers and their tributaries are drained. The Amazon Basin is the largest of this type, containing drainage from an area of more than 3 million square miles.
Structural basins, formed by tectonic activity and the natural processes of weathering and erosion, are found predominantly in dry regions. An example of this type of basin is Death Valley, which is located in California and is approximately 282 feet below sea level.
Ocean basins, the largest depressions on earth, have continental shelves forming their sides. There are five major ocean basins: the Pacific basin, the Atlantic basin, the Indian Basin, the Arctic basin and the Southern basin. These basins are constantly changing due to tectonic activity, such as seafloor spreading and subduction. Due to their depths of thousands of feet below the ocean’s surface, ocean basins remain the most elusive to scientists.