Beach Formation

The sea as well as being a destructive force can also be constructive. The sea can move great quantities of sand enough to form a beach. In many places the forming of a beach and its removal is a seasonal cycle.

Winter storms can remove great swathes of sand right down to the underlying rock. During the spring the sand is deposited again recreating a sandy beach. This type of beach puts a great strain on living organisms. Those burying in the sand are disturbed or swept away in the winter. While those that have established themselves over the winter by fixing to the previously underlying rocks are smothered under tons of sand in the spring.

An important natural process in the formation of the shore is longshore drift. Not all waves approach parallel to the beach but instead break obliquely. These waves carry sand and pebbles obliquely up the beach, with the backwash runs directly down the beach. This results in the sand and pebbles being gradually moved sideways along the shore.

Man made structure such as harbours will provide the condition for a sandy beach to build up, such as in St Ives and Hayle. The provision of shelter to protect the shipping inside the harbour slows the flow of water, so any sand it is carrying falls to the bottom. This is often to such a degree that it needs to be regularly dredged.