NCERT Notes: Geography- Minor Relief of the Ocean floor - Testbook

Exploring the Minor Relief of the Oceans

Here are some of the minor relief features present in the ocean floors:

• Mid-Oceanic Ridges
• Seamounts
• Guyots
• Trenches
• Canyons
• Ridges
• Hills
• Sleeps
• Fracture Zone
• Atolls
• Island Arcs
• Coral reefs
• Sea Scarps
• Submerged Volcanoes

Mid-Ocean Ridges

• Mid-oceanic ridges are underwater mountain ranges formed by plate tectonics.
• These ridges consist of two chains of mountains separated by a large depression.
• These mountain ranges can have peaks as high as 2,500 m, with some even extending above the ocean’s surface.
• Examples of Mid-oceanic ridges include the South Atlantic Ridge in the Atlantic Ocean, the East Indian Ridge in the Indian Ocean, and the West Pacific Ridge in the Pacific Ocean.

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Seamount

• Seamounts are mountains with pointed peaks that rise from the seafloor but do not reach the surface of the ocean.
• They are typically of volcanic origin.
• Seamounts can be as tall as 3,000-4,500 m.
• An example of a seamount is the Cobb Seamount in the Pacific Ocean.

Submarine Canyons

• Submarine Canyons are narrow, steep-sided valleys that originate either within continental slopes or on a continental shelf.
• The Capbreton Canyon in the Bay of Biscay and the Ganges Canyon in the Bay of Bengal are examples of submarine canyons.

Guyots

• Guyots are flat-topped seamounts, also known as table mounts.
• They are evidence of slow subsidence through various stages to become flat-topped submerged mountains.
• It is estimated that more than 10,000 guyots and seamounts are present in the Pacific Ocean alone.

Atoll

• An atoll is a ring-shaped coral reef that encloses a lagoon either partially or completely.
• These are typically low islands found in tropical oceans.
• They may enclose a part of the sea (lagoon), or occasionally a body of brackish, fresh, or highly saline water.

Reefs

• A reef is a mainly organic deposit made by living or dead organisms that form a mound or rocky elevation like a ridge.
• Coral reefs are a common feature of the Pacific Ocean, often associated with seamounts and guyots.
• The Great Barrier Reef off the coast of Australia is the world's largest reef.
• As the reefs may extend above the surface, they can be dangerous for navigation.

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