Paragraph on “How do we know what the bottoms of oceans are like?” complete paragraph for Class 9, Class 10, Class 11 and Class 12

How do we know what the bottoms of oceans are like?

Over two-thirds of the Earth’s surface is covered with water. Most of this is very deep and we call it ocean. People cannot go down very far because the pressure of the water on them increases the deeper they go. Deep-sea divers wear protective clothing to stop their bodies being crushed. However, people have gone down to great depths using specially constructed containers.

An easier way to find out what the ocean bed is like is to use echo sounding devices. A ship, moving slowly along the surface of the ocean, sends down sound waves. These are reflected back by the ocean bed and picked up by a receiver on the ship. We know how fast sound travels in sea-water. By measuring the time between sending out and receiving the sound waves, the distance the sound waves have travelled can be worked out. Half of this distance is the depth of the ocean bed. By repeating these readings at many different points, the bed of the ocean can be mapped out.

Using echo sounding we know that the deepest part of the ocean is II km (7 miles) deep! Also, that there are valleys, hills and mountains on the ocean bed and the highest sub-marine mountain is nearly as high as Mount Everest!