Along a coastline there are features created by erosion. These include cliffs, wave-cut platforms and wave-cut notches. There are also headlands and bays, caves, arches, stacks and stumps.
One of the most common features of a coastline is a cliff. Cliffs are shaped through a combination of erosion and weathering - the breakdown of rocks caused by weather conditions.
Soft rock, eg sand and clay, erodes easily to create gently sloping cliffs. Hard rock, eg chalk, is more resistant and erodes slowly to create steep cliffs.
Headlands are formed when the sea attacks a section of coast with alternating bands of hard and soft rock.
The bands of soft rock, such as sand and clay, erode more quickly than those of more resistant rock, such as chalk. This leaves a section of land jutting out into the sea called a headland. The areas where the soft rock has eroded away, next to the headland, are called bays.
Geology is the study of the types of rocks that make up the Earth's crust. Coastlines where the geology alternates between strata (or bands) of hard rock and soft rock are called discordant coastlines. A concordant coastline has the same type of rock along its length. Concordant coastlines tend to have fewer bays and headlands.
Along the coastline of the Isle of Purbeck in Dorset, there are both discordant and concordant coastlines. The discordant coastline has been formed into Studland Bay (soft rock), Ballard Point (hard rock), Swanage Bay (soft rock) and Durlston Head (hard rock). After Durlston Head, the strata stop alternating and the coastline is made up of hard rock. This concordant coast has fewer features.
Weathering [weathering: The gradual breakdown of rocks due to the effects of weather. ] and erosionerosion: Erosion is the process whereby rock or soil is worn away by the action of the wind, waves or water. can create caves, arches, stacks and stumps along a headland.
The formation of Old Harry Rocks in Dorset.