(a) Draw a diagram of the relief of the ocean floor showing the following (i) Continental shelf (ii) Continental slope (iii) Ocean deep (b) Describe the mai...

(a) Relief of the ocean floor

(b) Characteristics of two features

Continental shelf

• It is the shallow, submerged extension of the continental landmass from the coast to the shelf break.
• It has a broad and gentle seaward slope and is usually less than about 200 m deep.
• It is covered mainly by sediments and is affected by wave action, erosion and deposition.
• Its shallow, well-lit water supports abundant plankton and marine life.

Ocean deep

• Ocean deeps are long, narrow and very deep depressions or trenches in the ocean floor.
• They form the deepest parts of the oceans, commonly exceeding 6,000 m in depth.
• They commonly occur near island arcs or continental margins and are associated with earth movements, earthquakes and volcanic activity.
• Fine deposits such as clay and oozes may accumulate on their floors.

(c) Economic importance of continental shelves

• They are important fishing grounds because sunlight penetrates the shallow water, encouraging the growth of plankton, which is food for fish.
• They provide employment and income in fishing, fish processing, boat building and related industries.
• They contain valuable mineral and energy resources, especially offshore petroleum and natural gas.
• They provide suitable locations for the development of ports, harbours and other coastal facilities.
• Sand, gravel and shells may be obtained from shelf deposits for construction and industrial uses.