How does the sea shape the coast?
The sea can cause different landforms according to weather the area has a lot of erosion or deposition.
Erosion Coastlines
These are made by wearing away of the land. In stormy weather the sea breaks down the shore by hurling rocks and stones towards the coast, or carrying lighter material away with it. Areas with soft rocks are worn away more easily than those with hard rocks – hard rocks produce steep cliffs (Lower Coralline Limestone at Dingli Cliffs) while soft rocks produce steep slopes (e.g. Blue Clay at Gnejna). The soft rock becomes the bay, whereas the hard rock becomes the headland (e.g. Ras il-Pellegrin, Ras id-Dawwara). In the case of cliffs, the sea cuts a wave-cut notch where it touches and then deepens it. When it is deep enough, the overhanging rock falls down into the sea. Initially the headland will take on the brunt of the waves’ strength. Later on it will also get eroded.
Cliff Erosion Formation of a Bay
Erosion of Headland
The harder the rock, the longer will it take for the headland to erode. The sea will first attack the headland where it finds a crack. The crack will later widen due to continued erosion, forming a cave. The roof of the cave may be perforated to form a blowhole. Later on the cave will perforate the headland to the other side, forming an arch (e.g. Blue Grotto, It-Tieqa Dwejra). When the arches’ roof gets too thin, it will collapse, leaving just a stack. Later on, the stack will get eroded to produce a stump.
Deposition landforms
These include beaches and spits. They are formed when material worn away from one part of the coast is carried along and dropped somewhere else. They are formed in areas where the sea is calm and does not have enough energy to erode the beach. Beaches can be of two types – sandy beaches (e.g. Ghadira, Ramla il-Hamra) and pebbly beaches (Bahar ic-Caghaq). Sandy beaches indicate an area of calmer water than a pebbly beach, where the pebbles are deposited due to strong waves. A spit is a special type of beach which extends into the sea. It needs to have very calm and shallow waters and currents always coming from the same direction. When it extends across the mouth of a bay it is called Tombolo. In Malta we have no spits.