ABSTRACT
The far-reaching oceanic waters on the surface of Earth are one of the characteristics of our world, and the reason why Earth is referred to as the Blue Planet. The waters of the three oceans (the Atlantic, the Paci c, and the Indian) together with those along the edges of the continents, which were explored successively and named as the various seas, comprise 510 × 106 km2 of the surface area of the earth (71%), while the landmasses comprise 149 × 106 km2. These oceanic waters are not distributed evenly across Earth’s surface; 80.9% of the surface area of the southern hemisphere (210 × 106 km2) is covered by oceanic waters, while in the northern hemisphere just 60.7% (or 150 × 106 km2) is covered by waters. The volume of oceanic waters (including the seas and sea ice) comprise 97.957% of all the water resources on the earth (Duxbury et al. 2002). The zone stretching along the shoreline where the bottom slopes gently down toward the open ocean to the region where the underwater slope drops off and depth increases dramatically is known as the continental shelf. The steep gradient that drops down to the oceanic crust is known as the continental slope. In older textbooks, shelf waters are de ned as those that stretch from the shoreline to the place marked by an isobath of 200 m. In reality, the tectonic features of the ocean bottom dictate that the depths of the continental shelf edge range from 20 to 500 m (Duxbury et al. 2002). Similarly, the depth reach of the continental slope is as much as 3000 m. The width of the shelf depends on geographical positioning, and can range from about 15 to 1000 km.
