Oceans and their coastal margins

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Covering over 70% of the Earth?s surface, oceans are of great importance to humans in a number of ways. This optional theme provides an introduction to the physical characteristics and processes of the oceans with particular reference to the atmosphere?ocean link, concentrating on the important role that oceans play in influencing climatic conditions. Issues arising from the oceans as resource bases are also considered.

The emphasis in the section on coastal margins is on management. Consequently, a detailed study of the physical characteristics and processes of coasts is not required, although some knowledge is essential for understanding management strategies.

The material has been organized in this theme to provide a sequenced structure for teaching. Attention is drawn to the need to provide detailed examples or case studies in several topics.

Definitions

The definitions of the terms used in studying this theme, ?Oceans and their coastal margins?, vary from one source to another. To avoid confusion, the following definitions are given and expected of students.

 

Term Definition

Advancing coasts

Depositional coasts that are growing as a consequence of sediment deposit and/or the infill of coastal marshes. Advancing coasts may also arise from a negative change in sea level (sea level fall or uplift of land).

Exclusive economic zone (EEZ)

An area in which a coastal nation has sovereign rights over all the economic resources of the sea, seabed and subsoil, extending up to 200 nautical miles from the coast.

Littoral drift

The movement of sediment along a coast by wave action; also called longshore drift.

Oceanic conveyor belts

A global thermohaline circulation, driven by the formation and sinking of deep water and responsible for the large flow of upper ocean water.

Retreating coasts

Coasts along which the dominant processes are erosional, resulting in the coastline moving inland. Retreating coasts may also be caused by a positive change in sea level (sea level rise or a fall in land level).

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