Do you know what are the main types of coasts? In 1952, a scientist called H. Valentine grouped all the coasts of the world into two main divisions. He called these two types advancing coasts and retreating coasts. Advancing coasts many is the result of the coastal land or they may be built outwards by deposition.
Retreating coasts occur when the land is sinking or when it is being eroded by the force of the waves. Both these processes may be taking place at the same time on many beaches, and it is only by carefully observing an area over a period of many years that scientists are able to tell which process is the more important in that area.
There are many features associated with these two main types of coastline which enable you to recognize them quite easily. For example, if the sea-level rises or the land sinks, it is clear that many of the features that were present on the land and formed by terrestrial processes will become flooded by the sea and drowned.
If it was hilly area before the sea advanced, you might expect to see bays, estuaries, raise (drowned river valleys). And gulfs separated by projecting area o dry land called headlands and peninsulas. The fiords of Scandinavia are typical of submergence.
If you were to go to many parts of the northwest coast of Scotland, you might notice a different situation, however. On the Isle of Arran for example, behind the present beaches, you might be able to recognize what appear to be other typical sea beaches.
These beaches are higher than the level of the highest seas there today. They are called raised beaches and are old sea beaches which have been raised above the present sea level. Sometimes, as many as four levels of raised beaches can be seen.
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