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- The portion of the continents that are submerged under water and borders the coastal areas is known as a continental shelf.
- They are broad, shallow and gently-sloping plains covered by water.
- The continental shelf does not extend into the ocean uniformly. Near some coasts, it is narrow while in some parts it may extend for hundreds of kilometres. For example, they are almost absent or very narrow along the coasts of Chile, Sumatra etc., while the Siberian coast near the Arctic Ocean is around 1500 km in width.
- Generally, its depth from the sea level is about 180 m to 200 m.
- As the sunlight reaches this part of the ocean bed, it is rich in plankton. These millions of microscopic organisms found in sea water are an important food for fish. Millions of fishes thrive here. The shelf has some of the richest fishing grounds in the world, such as the Grand Banks and Georges Bank in North America.
- The continental shelves contain the world’s largest reservoirs of natural oil and gas. For example, the Mumbai High in Arabian sea. Besides oil and gas, minerals are also found here.
- Diamonds, chromite, ilmenite, magnetite, platinum, gold and phosphorite deposits are common. Sand, gravel aggregates and industrial silica sand are the most important of hard minerals now extracted in the near offshore zone.
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