The surface of the earth is covered by two contrasting media; land and sea. They meet at the coast. There are, of course, glaciers that span parts of both the land and sea such as in Greenland, Iceland, parts of Alaska and the Canadian Arctic, and on Antarctica. Each of these two surfaces may cover millions of square kilometers over continents and oceans or much less in the case of small oceanic islands or some lakes within continental masses. Nevertheless, a narrow coastal zone separates these two major parts of the earth’s surface.

Map measurements of the world’s coastline length have yielded a figure of 500,000 km. However, when all of the very real and intricate coastal crenulations are considered, the actual length is probably closer to 1,000,000 km. Added to this is the fact that 40% of the 6,000,000,000 people presently inhabiting the earth live within 100 km of a coastline. From these observations, it can be seen that coasts are a very major geo-morphic and social feature on the face of the planet. And for this reason, scholars in a multitude of disciplines have long been studying the many facets of the zone where the land meets the sea.