Ocean Floor topography
The topography at the floor of the oceans are divided into four sections : 1. The Continental Shelf 2. The Continental Slope 3. The Ocean Trough and 4. The Ocean Deeps.
1. The continental Shelf : The Continental Shelf is that part of an ocean that lies close to the conteinantal margin. The depths of the shelves vary from 150 to 200 metres. Similarly, the width varies from place to place. Broad continental shelves are good fishing grounds because they contain suitable conditions for the growth of platkton. Plankton provides food for fish. For example, the broad continental shelves of Northwestern Europe and the coastal areas around Japan are the largest fishing grounds in the world.
2. The Continental Slope: The Continental slope lies beyond the continental shelf, where the ocean floor slopes downwards. The steep slope connects the continental shelf with the deep ocean floor. The average depth of the slope varies from 3000 to 6000 metres. The depth of the ocean floor suddenly increases where the shelf ends.
3. The Ocean Trough : The Continental slope ends at the ocean trough, which is like a deep, underwater plain. It consists of islands, mountain ranges, plateaus, deep valleys and plains. These features cover about 40% of the oceans' floors. Mid- Atlantic Ridge is the largest mountain
range in the ocean. This range is over 1400 km in length. This ridge has a deep valley where volcanic and earthquake disturbances are quite common. These volcanoes erupt underwater as they do on land. Islands like Hawaii in the Pacific Ocean and the Azores in the Atlantic Ocean were formed through volcanic activity under the ocean. The floor is carpeted with sediment formed by the minute remains of creatures and rocks.
4. The Ocean Deeps : Trenches are formed deep in the oceans. These trenches are very narrow and deep in nature. There are numerous trenches in the Pacific Ocean. The Mariana Trench, 11 033 metres in depth, is the deepest part of the world. Even Mount Everest (8848 metres) would be submerged completely in this trench.