OCEAN TOPOGRAPHY

OCEAN TOPOGRAPHY

1. An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3,000 metres 9,800 ft and 6,000 metres 20,000 ft.

2. The creation of the abyssal plain is the result of the spreading of the seafloor plate tectonics and the melting of the lower oceanic crust. Magma rises from above the asthenosphere a layer of the upper mantle, and as this basaltic material reaches the surface at mid-ocean ridges, it forms new oceanic crust, which is constantly pulled sideways by spreading of the seafloor.

3. Owing in part to their vast size, abyssal plains are believed to be major reservoirs of biodiversity. They also exert significant influence upon ocean carbon cycling, dissolution of calcium carbonate, and atmospheric CO2 concentrations over time scales of a hundred to a thousand years.

4. Abyssal plains were not recognized as distinct physiographic features of the sea floor until the late 1940s and, until very recently, none had been studied on a systematic basis.

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