The Earth Contents

2. Plate Tectonics

The abyssal plain lies beyond the continental shelf

The abyssal plain is underlain by oceanic crust, which is covered by a layer of sediment that becomes deeper and older away from the mid-ocean ridge, towards the edge of the continents. These ocean deeps represent about 30% of the 'surface' of the Earth, which is more than the entire area of the continents. Although called the abyssal plain, this region is not entirely flat; instead there are a number of spectacular hills mostly of volcanic origin. The highest of these hills reach the surface as islands (Fiji, Tahiti, and the Azores), but most are completely submerged. In tropical seas these islands are overgrown with coral where they reach or approach the sea surface.

The abyssal plain is the location of many coral beds.

What are some of the characteristics of the abyssal plain?