OCEAN BASIN AND ITS FEATURES

Ocean Basin simply refers to the an extensive depression of the earth’s surface in which an ocean lies. Ocean Basin is divided into five basically, namely: (1) Continental shelf (2) Continental Slope (3) Deep Sea Plain (4) Ocean Ridge (5) Ocean Deep/Trench. See the diagrams for illustration.

Continental Shelf:
Continental shelf is simply part of the continental crust which extends into the sea. This results into an area of relatively shallow water known as a shelf sea. The average width of continental shelves is about 80 km (50 miles). The depth of the shelf also varies, but it is generally limited to water shallower than 150 m (490 ft). Continental shelf is the most important of all the features of ocean basin. It is the only part of the ocean basin where sunlight reaches its floor after penetrating its water. As a result, plants grow on it. The shelves make up less than 10 percent of the total area of the oceans. Yet all of the ocean’s plants and many types of algae live in the sunny waters. Plants and algae make continental shelves rich feeding grounds for sea creatures. While these sea creatures come to continental shelves to feed, fishermen and fishing companies with their fishing trawlers seize to opportunity to catch them. So, we all have food to eat.

Continental Slope:
Continental Slope is the slope between the outer edge of the continental shelf and the deep ocean floor. It connects the continental shelf to the deep ocean plain.

Deep Sea Plain
Deep Sea Plain is also called Abyssal Plain. It is an underwater plain(flat) on the deep ocean floor, usually found at depths between 3,000 metres (9,800 ft) and 6,000 metres (20,000 ft). Abyssal Plain is very vast. It constitutes about two-third of the ocean basin. For the Deep Sea Plain, the height of the water column is divided into three zones namely: (1) Sunlight Zone (0 – 200m) (2) Twilight Zone (200 – 1000m) (3) Midnight/Darkness Zone (Beyond 1000m). – (See the diagram).

For the Sunlight Zone, light from the sun is well detected. Sunlight gets to every part of the 200m range. Photosynthesis takes place here. For the Twilight Zone, no significant sunlight is detected. Photosynthesis cannot take place here. You should know what that means. For the Midnight/Darkness Zone, sunlight does not get here at all, even during the very hot sunny day!

Ocean Ridge
Ocean ridge is an underwater mountain range. Just like we have mountains on the continental crust, there are mountain ranges in the the oceans too.

Ocean Deep/Trench
Ocean trench is basically a long, narrow, deep depression or ditch in the ocean bed. Mariana Trench is the deepest part of the world’s oceans. It is located in the western Pacific Ocean, to the east of the Mariana Islands. The trench is about 2,550 kilometres long with an average width of 69 kilometres. The deepest part of the ocean in the world the Challenger Deep. This is located in Mariana Trench, at a depth of 11,034 m (36,201 ft) below sea level. If mountain Everest or mountain Mauna Kea is placed inside the Challenger Deep, each of them will be completely submerged! If a metal like shotput is dropped from the surface of the ocean into the Challenger Deep, it will take about 36 to 38 minutes to land on the the floor of the Challenger Deep. If a stone or a pebble of the same size is dropped, it will take over one hour to reach the bottom! The water pressure at the bottom of Challenger Deep is over 1000 times the pressure at the surface! The temperature there is just above freezing temperature!

(Photo Credits: www. mrtrent.com)
(Photo Credits: geologycafe.com)

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