Where sea level rises relative to the land, deep inlets are formed by the sea flooding the lower part of river valleys. The headlands between valleys are exposed to wave action, and are gradually eroded to form cliffs. Within the valleys, sheltered conditions permit the deposition of eroded material, so the inlets gradually fill with sand or silt (Figure 8.10). This submergent type of coastline is evident around the south-west peninsulas of the British Isles and the flooded river valleys are called rias.
If land and sea level become stable for any long period, the headlands are progressively cut back reducing the depth of inlets until they become bays containing beaches between extensive stretches of high cliff. Eventually, when the protecting headlands have been completely obliterated, the bays themselves become exposed to erosion and the coastline then tends to become fairly uniform, consisting mainly of cliffs with little if any beach, i.e. a mature coastline.
Was this article helpful?
Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.