The Ocean at a Glance

The oceanic waters of earth have a combined area of about 140 million square miles. In the Southern Hemisphere the oceans cover about 81 percent of the surface, while in the Nothern Hemisphere they cover approximately 61 percent. The oceans are intercommunicating bodies of water which include their gulfs and seas.

The floor of the ocean is commonly divided into four main parts. The first is the continental shelf which slopes gently outward from the shore of the continent. It is about forty miles wide and four hundred feet deep. At the end of the continental shelf the sea floor falls sharply to a very deep seabed. This sea floor is the second part and is usually known as the continental slope. At the base of this continental slope is the sediment which forms the third part, the continental rise. The fourth is the floor of the sea beyond the continental rise, the deep seabed. On the deep seabed are strings of mountain known as mid-oceanic ridges, isolated mountains known as seamounts, deep valley or deep sea trenches and plateaus or guyots.