Test: Water (Oceans) - UPSC

Ocean floor has varied and complex features.

Surface salinity is lowered in coastal regions because of the inflow of fresh water from rivers.

Salinity is the saltiness or dissolved salt content of a body of water. It is a general term that is used to describe the levels of different salts, such as sodium chloride, magnesium and calcium sulfates and bicarbonates.

Submarine canyons have been found carving deep cracks that extend from near shore to deep sea edge of the oceanic shelf.

Salinity, generally, increases with depth and there is a distinct zone called the halocline, where salinity increases sharply. Other factors being constant, increasing salinity of seawater causes its density to increase.

A mid-ocean ridge is an underwater mountain system formed by plate tectonics and consequently is termed a divergent plate boundary.

The factor affecting the distribution of temperature of ocean water is latitude, unequal distribution of land and water,prevailing winds ocean currents.

The Pacific Ocean has the most coral reefs amongst all the oceans. There are about twice as many coral species in Pacific Ocean reefs as in Atlantic Ocean reefs.

Arctic Ocean is the smallest ocean in the world. It is located within the Arctic Circle and surrounds the North Pole. It is the shallowest and smallest of all the oceans in the planet, more than five times smaller than the Atlantic and Indian oceans. Its surface area is approximately 14.056 million square km, making it the smallest ocean on the planet.

The correct answer is C: Oceanic Deep. An oceanic deep, also known as a trench, is a steep-sided, narrow basin that is located at the base of continental slopes and along island arcs. It is associated with active volcanoes and strong earthquakes, making it a very significant feature in the study of plate movements. It is much deeper than the surrounding ocean floor, which is usually 3-5 km deep. Seamounts, Atolls, and Guyots, on the other hand, are all minor relief features of the ocean floor. Seamounts are mountains with pointed summits that rise from the seafloor but do not reach the surface of the ocean. Atolls are low islands consisting of coral reefs surrounding a central depression. Guyots are flat-topped seamounts that have been eroded by waves.