The outlines of coasts are as varied as the rocks that form them. Some of them are fronted by long line of vertical cliffs. Elsewhere you find sheltered coves. Frequently the rocks have been sculpted into tunnels, caves or arches too. All these features are alike in one respect. All are formed by the thunder of pounding waves which are said to be the architect of all these splendors.
Cliffs are sculpted by seas. Waves keep attacking, cutting the cliff back into the rising slope and so increasing its height. Sea cliffs begin as steep slopes plunging down to the water’s edge. In the first stage of development, the pounding surf carves a shallow notch along the base of the slope. As the notch deepens, the overlying rocks collapse and a cliff begins to form.
Many other forces contribute to the sculpting of coastal cliffs. Crashing against the rocks, the waves trap air in cracks and crevices and cause explosive bursts of high air pressure. Repeated again and again, these miniature explosions can loosen enormous chunks of rock and send them toppling into the sea. This process called chemical weathering weakens the rock. Pieces are made loose when fresh water freezes and expands in cracks. Plants and animals also play a major role by boring holes into rocks, increasing its chances of getting attacked by the waves.
If the rocks are uniform in their composition, a long straight line of cliffs will form. But more often the rocks vary in their resistance to erosion. The weaker portions of the rocks are quickly worn away and the coast becomes intended with countless coves and cliffs. The more resistant rock formations remain intact, projecting out to sea as peninsulas.
Caves start to form slowly penetrating rocky cliffs. As the opening grows larger, the heaving waters wrench great chunks of rocks from the walls. And so the opening continues to grow larger and larger. The resultant caves become places of special beauty.