7. Deep-Sea Plains or Abyssal Plains

The deep-sea plains or abyssal plains are undulating underwater plains found on the deep ocean floor. These plains extend from continental rise to the mid-oceanic ridges covering for abouttwo-thirdof the ocean floor. The slope gradient is very gentle, and it appears as a uniform flat and featureless plain. Though they were once regarded as featureless plains, now the modern devices have shown the irregularities as in the continental plain or surface. The floor of a abyssal plain is covered by a thick layer of sediments composed of clay, silt and sand, brought by the rivers that usually cover these plains. 

 

 

Seas that favour the abundant growth of organisms have a thick layer of sediments formed from the remains of living things. These sediments are called oozes. Some of the open seas that do not support enough life to produce ooze on the floor are covered with a type of sediment called red clay. Red clays are volcanic in origin or made up of tiny particles brought by wind and rivers. The abyssal plains are likely the most level areas on the earth. These are often characterized by features like abyssal hills, seamounts, guyots, coral, atoll etc.

 

Since the majority of the world's largest rivers empty their sediments into either Atlantic or Indian Ocean, the Abyssal plains in the Atlantic and the Indian Oceans tend to be extensive than the Pacific Ocean.