HYDROSPHERE (OCEAN) Part 01

HYDROSPHERE (OCEAN) Part 01

The earth is called the blue planet. More than 71 percent of the earth is covered with water and 29 percent is with land. Hydrosphere consists of water in all its forms.

As running water in oceans and rivers and in lakes, ice in glaciers, underground water and the water vapour in atmosphere, all comprise the hydrosphere.

Hydrography is the science that measures and describes the physical features of the navigable portion of the Earth’s surface and adjoining coastal areas.

OCEAN
An ocean is a body of saline water that composes much of a planet’s hydrosphere. On Earth, an ocean is one of the major conventional divisions of the World Ocean. These are, in descending order by area, the Pacific, Atlantic, Indian, Southern (Antarctic), and Arctic Oceans.

MAJOR OCEANS

OCEANS    SALIENT FEATURES
Pacific Ocean:    

The Pacific Ocean is by far the world’s largest ocean at 55,557,000 sq km. It covers 28% of the Earth and is equal in size to nearly all of the land area on the Earth. The Pacific Ocean is located between the Southern Ocean, Asia, and Australia in the Western Hemisphere. It has an average depth of 13,215 feet (4,028 meters) but its deepest point is the Challenger Deep within the Mariana Trench near Japan. This area is also the deepest point in the world at -35,840 feet (-10,924 meters).
 

Atlantic Ocean:    

The Atlantic Ocean is the second largest of the world’s oceans, with an area of about 106,460,000 square kilometers. It covers approximately 20 percent of the Earth’s surface and about 29 percent of its water surface area.
 

Indian Ocean:   

The Indian Ocean is the only ocean named after a country, that is, India. The shape of ocean is almost triangular. In the north, it is bound by Asia, in the west by Africa and in the east by Australia.
 

Southern Ocean:   

The Southern Ocean, also known as the Antarctic Ocean or the Austral Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica.
 

Arctic Ocean:    

The Arctic Ocean is located within the Arctic Circle and surrounds the North Pole. It is connected with the Pacific Ocean by a narrow stretch of shallow water known as Berring strait. It is bound by northern coasts of North America and Eurasia.

OCEAN TRENCHES
•    Ocean trenches are steep depressions in the deepest parts of the ocean [where old ocean crust from one tectonic plate is pushed beneath another plate, raising mountains, causing earthquakes, and forming volcanoes on the seafloor and on land.


OCEANIC RIDGES
•    A mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics. This uplifting of the ocean floor occurs when convection currents rise in the mantle beneath the oceanic crust and create magma where two tectonic plates meet at a divergent boundary.

SEAMOUNT
•    A seamount is a mountain rising from the ocean seafloor that does not reach to the water’s surface, and thus is not an island, islet or cliff-rock.

SUBMARINE CANYONS
•    Submarine canyon is steep-sided, V-shaped valley that is formed at outer edge of continental shelf and continue across the slope. Meanwhile at its lower end usually leads
to an abyssal fan (submarine fan), a fan-shaped, big pile of sediment lying on the sea floor.