In addition to marine processes, there are also sub-ariel (land-based) processes which shape the coastline. These processes come under the general headings of weathering and mass movement. Solution was included in the marine processes listed above because it is a major pricess that combines with erosion to produce coastlines. Other weathering processes that can be effective include frost shattering, exfoliation (thermal expansion), biological weathering and other forms of chemical weathering than solution.
Biological weathering is quie active on coastlines. Some marine organisms, such as the piddock (a shellfish), have specially adapted shells to enable them to drill into solid rock. They are particularly active in chalk areas where they can produce a sponge-like rock pitted with holes. Seaweed attaches itself to rocks and the action of the sea can be enough to cause swaying seaweed to prise away loose rocks from the sea floor. Some organisms, algae for example, secrete chemicals capable of promoting solution.
Mass movemewnt is common on coastlines, particularly those that are steep, and includes the following:
Biological weathering is quie active on coastlines. Some marine organisms, such as the piddock (a shellfish), have specially adapted shells to enable them to drill into solid rock. They are particularly active in chalk areas where they can produce a sponge-like rock pitted with holes. Seaweed attaches itself to rocks and the action of the sea can be enough to cause swaying seaweed to prise away loose rocks from the sea floor. Some organisms, algae for example, secrete chemicals capable of promoting solution.
Mass movemewnt is common on coastlines, particularly those that are steep, and includes the following:
- rock falls from cliffs undercut by the sea
- landslides on cliffs made from softer rocks or deposited material, which slip down when lubricated
- mudflows - heavy rain can cause fine material to flow downhill where it sometimes takes on the appearance, and movement, of a glacier
- where softer material overlies much more resistant materials, cliffs are often subject to slumping. With excessive lubrication, whole sections of the cliff face may move downwards with a slide plane that is concave, producing a rotational movement. Slumps are a very commin feature of the British coast, particularly where glacial deposits form the coastal areas, e.g. east Yorkshire and north Norfolk. The below picture shows a typical rotational in an area where glacial deposits form cliffs on top of an impermeable clay layer.