Coastal Processes
Coastal landscapes are shaped by a variety of processes, including weathering, mass movement, and wave action. These processes work together to create and modify coastal features over time.
Weathering is a crucial process in coastal landscapes, with two main types: mechanical and chemical. Mechanical weathering breaks down rocks without changing their chemical composition. This process is particularly effective in coastal areas where temperature fluctuations are common.
Example: In coastal regions where temperatures alternate around freezing, water enters cracks in rocks. As the water freezes, it expands, creating pressure that widens and eventually breaks these cracks.
Chemical weathering, on the other hand, breaks down rocks while altering their chemical composition. This process is facilitated by rainwater, which contains carbon dioxide, forming a weak carbonic acid.
Vocabulary: Carbonic acid - A weak acid formed when carbon dioxide dissolves in water.
The carbonic acid reacts with calcium carbonate in rocks, dissolving them over time. This process is particularly significant in areas with limestone cliffs.
Mass movement is another critical process affecting coastal landscapes. It involves the shifting of rocks and material down a slope due to gravity.
Definition: Mass movement - The downslope movement of rock and soil under the influence of gravity.
Mass movement occurs when the force of gravity acting on a slope becomes greater than the forces supporting it. This process can lead to rapid coastal retreat and creates distinctive features in the landscape.
Highlight: Mass movement is more likely to occur when the material holds water, as water acts as a lubricant and increases the weight of the material.
One of the results of mass movement is the creation of a scarp, which is a steep cut in the side of a slope.
The influence of wave types on coastal erosion and deposition is a key factor in shaping coastal landscapes. The type of wave that reaches the coast is determined by the fetch, which is the distance the wind blows over the sea.
Vocabulary: Fetch - The distance over which wind blows across open water, affecting wave formation.
There are two main types of waves: destructive and constructive. Destructive waves are characterized by high frequency and steep profiles. They have a powerful backwash and a weak swash, making them effective at eroding the coast.
Constructive waves, in contrast, have a low frequency and are low and long. They have a powerful swash and a weak backwash, making them more likely to deposit material on the coast.