A low-lying area on the Earth's surface in which thick layers of sediment have accumulated. Some basins are bowl-shaped while others are elongate. Basins form through tectonic processes, especially in fault-bordered intermontane areas or in areas where the Earth's crust has warped downwards. They are often a source of valuable oil.
An artificially enclosed area of a river or harbor designed so that the water level remains unaffected by tidal changes.