ICSE Class 9 Answered

An ocean basin is a depression in the surface of the Earth in which the ocean lies. Many trenches, ridges, canyons and plateaus exist in the ocean basin as a result of tectonic, volcanic, erosional and depositional processes. The chief features of the ocean basin are:

Continental Shelf: It is an area of sea bed which is adjacent to the coastline and is not as deep as the open ocean. The continental shelf is so shallow that even sunlight can reach the seabed.

The continental shelf is rich in oil, coal and non ferrous metals. One can find many types of plankton here. This makes the continental shelf the richest fishing grounds.

Continental Slope: The slope between the outer edge of the continental shelf and the deep ocean floor is known as the ocean slope. It occupies 8.5% of the total ocean area.

The continental slope consists of light continental rocks which lie over dense rocks of the ocean floor.

Deep Ocean Floor: Ocean floors are situated on the base of the continental slope. The depth of the ocean floors varies from 3000 to 6000 meters. On the ocean basins, many plateaus, plains and volcanic summits may be found.

The Ocean Deeps: Deep trenches are known as ocean deeps. Some of the ocean deeps are as deep as 36,000 feet. The deepest part in the ocean in the world is Mariana trench which is about 11,033 meters deep. Another deep trench is the Tonga trench which is more than 10,000 meters high.