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Deep-Ocean Basin


  1. Abyssal Plain: Abyssal plains is an underwater plain on the deep ocean floor, usually found at depths between 3000 metres & 6000 metres.
Characteristics:
a)     Abyssal plain is the most extensive relief zone of the ocean floor.
b)    The average slope gradient is almost 0.5áµ’.
c)     It covers nearly 40% of the ocean floor.
d)    It is flat & rolling submarine plain.
  1. Abyssal Hill: Abyssal hills a small hill that rises from the floor of an abyssal plain.
Characteristics:
a)     Covering more than 30% of the ocean floor.
b)    Height of this hill is less than 100m.
  1. Seamounts: Seamounts is an volcanic projections that developed above the abyssal plains that do not rise above the surface of the sea.
Characteristics:
a)     Seamounts are circular or elliptical.
b)    Height is of less than 1 km.
c)     Relatively steel slops of 20áµ’-25áµ’.
d)    Seamounts may be found alone or in groups of from 10 to 100.
  1. Guyots: Guyots are flat-topped seamounts or volcanic hills.
Characteristics:
a)     Guyots are flat-topped seamounts.
b)    Height is of less than 1 km.
  1. Ocean Trenches: Ocean trenches is an arc-shaped depression in the deep ocean floor.
Characteristics:
a)     Trenches are among the most active geological features on earth.
b)    These areas are the deepest part of the oceans.
c)     The trenches are curved because of the geometry of plate interactions on a sphere.
d)    The sides of trenches become steeper with depth.
  1. Island Arc: Island arcs is an curving chains of volcanic islands & seamounts, are almost always found paralleling the concave edges of trenches.
Characteristics:
a)     Island arcs is an curving chains of volcanic islands & seamounts.
b)    Trenches & Island arcs is form by tectonic & volcanic activity associated with subduction.
  1. Mid-Ocean Ridge: Mid-Ocean ridges is a seafloor mountain or volcanic that formed by plate tectonics that are most extensive relief features not only of the ocean basins but of the entire globe.
 Characteristics:
a)     MOR are the largest mountain chains of the globe.
b)    Not all of the MOR occupy central locations in the deep oceans basins.
c)     All of the MOR are of volcanic origin & consist of basaltic pillow lava.
d)   They are always associated with divergent plate margins & sea floor spreading.
Fig: Deep-ocean basin

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