NCERT Notes: Geography- Minor Relief of the Ocean floor

NCERT notes on important topics for the UPSC civil services exam. These notes will also be useful for other competitive exams like banking PO, SSC, state civil services exams and so on. This article talks about the Minor Relief of the Ocean Floors.

Minor Relief

The ocean floors can be divided into four major divisions and some minor relief features in the ocean floors like

  • Mid-Oceanic Ridges
  • Seamounts
  • Guyots
  • Trenches
  • Canyons

 

Mid-Oceanic Ridges
  • A mid-oceanic ridge is an underwater mountain range, formed by plate tectonics.
  • It is composed of two chains of mountains divided by a large depression.
  • The mountain ranges can have peaks as high as 2,500 m and some even reach above the ocean’s surface.
  • Examples for Mid-oceanic ridges:
    • Mid-Atlantic Ridge, Atlantic Ocean
    • East Pacific Rise
    • Pacific-Antarctic Ridge

Seamount
  • Seamounts are mountains with pointed peaks, mounting from the seafloor, and that do not reach the surface of the ocean.
  • They are volcanic in origin.
  • Seamounts can be 3,000-4,500 m tall.
  • An extension of the Hawaiian Islands in the Pacific Ocean which is known as The Emperor seamount is an example of seamount.

Submarine Canyons
  • Submarine Canyons are a kind of narrow steep-sided valleys.
  • It originates either within continental slopes or on a continental shelf.
  • Congo Canyon is regarded as the largest river canyon.
  • The Hudson Canyon is the best-known submarine canyon in the world.
  • The largest submarine canyon in the world is Zhemchug Canyon. 

Guyots
  • It is a flat topped seamount.
  • It is also known as a table mount.
  • They show evidence of slow subsidence through stages to become flat-topped submerged mountains.
  • It is expected that more than 10,000 guyots and seamounts occur in the Pacific Ocean only.

Atoll
  • It is a ring-shaped coral reef containing a coral rim that encompasses a lagoon incompletely or completely.
  • These are low islands found in the tropical oceans.
  • It may be a part of the sea (lagoon), or occasionally form encircling a body of brackish, fresh, or highly saline water.

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