Abyssal Plain - INSIGHTSIAS

• Abyssal plains are extremely flat and featureless plains of the deep ocean floor.
• In fact, the abyssal plains are likely the most level areas on the earth.
• Abyssal plains covering a major portion of ocean floor between the depth of 3000m to 6000m.
• They were once regarded as featureless plains but modem devices have shown that they are as irregular as the continental plain or surface.
• They have extensive submarine plateaus, hills, guyots and seamounts.
• The floor of the abyssal plain is covered by sediments.
• The plains close to the continents are covered mostly by sediments brought down from the land.
• But those seas which favour, an abundant growth of organisms have a thick layer of sediments, formed from the remains of living things.
• These sediments are called
• Some of the open seas do not support enough life to produce ooze on the floor.
• They are covered with a type of sediment called red clay which is of volcanic origin or made up of tiny particles brought by wind and rivers.

Submarine Ridges

• The lofty mountain systems which exist on the continents are also represented beneath the ocean waters.
• These oceanic mountains are known as submarine ridges.
• They are linear belts occurring near the middle of the oceans and are also called mid-oceanic ridges.
• All the mid oceanic ridges constitute a world-wide system which is interconnected from ocean to ocean.
• These ridges are intersected by faults.
• The oceanic ridge is the site of frequent earthquakes.
• Volcanism is common in ocean ridges and it produces many relief features.
• The Mid-Atlantic Ridge is the largest continuous submerged mountain ridge which runs from north to south in the Atlantic-Ocean.
• It is in the shape of S. At some places, the peaks, rise above the surface of water in the form of islands.
• Many of the islands are volcanic in origin. The East Pacific Ridge and Carlsberg Ridge are some of the important submarine ridges.

Seamounts and Guyots

• Scattered over the entire sea floor are thousands of submerged volcanoes with sharp tops called seamounts.
• Sometimes they rise above the sea as isolated Islands.
• Hawaii and Tahiti Islands are the exposed tops of volcanoes.
• Volcano rising above the ocean floor whose top has been flattened by erosion and is covered by water is called guyot.