Coast is the zone where the land meets and interacts with the sea. The coast may be made up of landforms such as beaches, headlands and cliffs. The line that separates the land and the sea is called the coastline. It is the general appearance of the coast, as seen from the sea.It is a dynamic environment that is constantly changing, just like the ocean, which shapes them. The Earth's natural processes, such as high tides, low tides, waves and various weather conditions have resulted in the erosion, accretion and reshaping of coasts. It also results in flooding and creation of continental shelves and drowned river valleys.
Waves
Waves are the rising and falling movements of the water surface. It is usually produced when winds blow across the sea or ocean. Coastal erosion occurs when waves wear away the rocks along the coast and carry away the eroded materials.Swash: the forward movement of waves onto the beaches.Tides are the daily changes in the sea level due to the movement of Moon and the Sun. Therefore, there is a high tide or a low tide every 12 hours. Tides cause changes in the depth of the marine and estuarine water bodies and produce oscillating currents known as tidal streams.
The strip of seashore that is submerged at high tide and exposed at low tide, the intertidal zone, is an important ecological product of ocean tides.
High tide:
Intertidal ecosystems are where organisms live between the low and high tide lines. At low tide, the intertidal is exposed, whereas at high tide, the intertidal is underwater (or ‘immersed’). Intertidal ecology therefore is the study of the interactions between intertidal organisms and their environment, as well as between different species of intertidal organisms within a particular intertidal community.Currents
Currents are flows of water that move either horizontally or vertically across oceans.
Ocean currents can flow for thousands of kilometers. They are very important in determining the climates of the continents, especially those regions bordering on the ocean. Perhaps the most striking example is the Gulf Stream, which makes northwest Europe much more temperate than any other region at the same latitude. Another example is the Hawaiian Islands, where the climate is somewhat cooler (sub-tropical) than the tropical latitudes in which they are located because of the California Current.
Headlands and Bays
Coasts are made up of rocks of different resistant. The less resistant rocks, such as chalk, erode faster, compared to the more resistant rocks, such as granite. The different rates of erosion along a coast produces an uneven coastline. Two types of landforms are formed- headlands and bays.
Headlands are formed when the more resistant rocks protrude out from the coastline. More resistant rocks are able to withstand erosion.
Bays are formed when the less resistant rocks curve inwards towards the coastline, as the rocks are eroded. Less resistant rocks are unable to withstand erosion.
Cliffs
Cliffs are usually formed by rock that is resistant to erosion and weathering. Sedimentary rocks most likely to form cliffs are sandstone, limestone, chalk, and dolomite. Igneous rocks, such as granite and basalt also often form cliffs.
A cliff is formed when waves repeatedly pound against a rocky coast. This weakens the rocks, causing lines of weakness to form in the rock face. Over time, the waves erode the coast to cut a notch along the lines of weakness. The notch may be further eroded to form a cave. The overhanging part of the notch or cave eventually collapses with repeated pounding of the waves. The part of the coast is left forms a cliff.
Beaches
A beach, or strand, is a geological landform consisting of loose rock particles such as sand, gravel, shingle, pebbles, cobble, or even shell fragments along the shore of a body of water. In other words, a beach is an accumulation of sediments on the coast. They occur along coastal areas where wave or current action deposit and rework sediments, or a stretch of land residing along a lake or river subject to erosion caused by rain fall. Beaches form when waves, tides or currents bring and deposit materials onto the shore.Beaches are constantly changing as their shapes and sizes are affected daily by waves, tides and currents. For example, during calm weather, constructive waves can help to deposit materials on the beach and build it up further. On the other hand, during coastal storms, strong waves will remove materials from the beach, causing erosion.
Tombolos
A tombolo is a deposition landform such as a spit or bar which forms a narrow piece of land between an island or offshore rock and a mainland shore, or between two islands or offshore rocks. They usually form because the island causes wave refraction, depositing sand and shingle moved by longshore drift in each direction around the island where the waves meet.Spits
A spit is a deposition landform found off coasts. It is a type of bar or beach that develops where a re-entrant occurs, such as at a cove, bay, ria, or river mouth. Spits are formed by the movement of sediments (typically sand). This movement of sediments is known as the longshore drift.
When the direction of the shore turns inland (re-enters) the longshore current spreads out or dissipates. No longer able to carry the full load, much of the sediment is dropped. This causes a bar to build out from the shore, eventually becoming a spit.
Thanks for viewing this blog and we hope you have an enjoyable learning experience through Geog Through Life! :D
