The marine erosion It consists of the erosion of the land on the coast and the removal of sediments from the sand dunes by sea currents, waves and sea currents. Waves are the most visible of the erosive elements, although tides and fauna also play an important role in this process. This type of erosion can therefore occur in rocks or sand.
When it occurs on coasts with few rocks, the erosion is more pronounced and faster. On the contrary, the rocky coasts erode more slowly. When there is a softer area than another in a reduced area, formations such as bridges, tunnels or natural pulars may occur..
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Maritime erosion is produced by two natural phenomena: waves and marine currents. On the other hand, it can also be produced by the action of some living beings, although this process does not intervene so much in erosion.
These have two stages of movement. The first occurs when the wave is constructive or swash; that is, when it is raised and hits the coastline.
The second happens when you become hangover or backwash, which is when it acts as a mantle and drags the sediments into the sea.
This process produces a continuous compression and decompression effect that in turn generates a suction effect capable of producing cliff collapses..
Its role is mainly dragging. The undertow of the wave produces a bottom current, which is a movement perpendicular to that of the shore current.
The currents also produce a parallel movement when the waves strike the coasts obliquely.
The differences between the high and low points of the tides also generate irregular currents. They are strongest when there is a large difference between low and high tide and the departure points at both times..
They are produced when waves collide with poorly settled sediments and wash them away. In addition, by constant action on the cracked rocks, they are destroyed as the waves penetrate violently and compress the air present.
It is generated by friction on the coast of rock fragments transported by waves and tides.
This erosion is fundamental mainly in the formation of steep coasts, cliffs and abrasion platforms..
The salts present in the sea dissolve many materials, mainly the limestone rock located in its interior, which will later be transformed into coral reefs or will collaborate with the abrasion process through its small particles..
Corrosion also acts in the surroundings of the sea, since the mist carries the same salts that make a dent in the constructions and in the means of transport of the coasts.
In this case, the animals are responsible for erosion. The sea contains animals that eat the rock (lithophagi) and others that transport the limestone rock dissolved in the sea to form coral reefs.
Vegetables also have an influence by staying in the crevices of the rocks, thus facilitating their breakdown..
There are two main causes of marine erosion:
The main cause that influences the erosive action of the sea is the same that allows and regulates its movement and that the sea itself also produces: it is the attraction generated by the gravity of the Sun and, above all, the gravity of the Moon in maritime waters.
The Moon attracts the nearest masses of water towards itself, in such a way that the part of the ocean that faces this natural satellite bulges towards it, while its counterpart on the other side of the Earth contracts in the opposite direction..
Why does this happen? The answer is inertia. The lunar gravity attracts the entire Earth, not just the sea, only that the Earth is rigid and does not bulge.
Solar gravity plays a secondary role: despite being more intense, it is at a greater distance.
According to the phases of the Moon and the point of terrestrial translation, the behavior of the tides varies and, by extension, maritime erosion occurs..
Storms are another factor to take into account. For example, on average in the Atlantic Ocean the waves have a force of 9765 Kg / m1, which can increase three times in force during heavy rains..
At the moment, cement blocks of more than 1000 metric tons have been displaced.
An immediate and devastating factor is the earthquakes that produce tsunamis, whose effect can change the relief where it hits in a matter of hours..
The effects of maritime erosion are basically reflected in the relief of the coasts. There are different variations in the reliefs, the most prominent are the following:
They are rocky or steep vertical slopes. They are formed by the impact of the waves and are the result of the wear of the eroded rock.
This rock gives way to erosion resistant rocks, these are usually sedimentary rocks.
They are eroded rocky platforms that appear when the tide is at low tide, giving rise to an extension of the coastline. Its function is to protect the rest of the coastline from marine erosion.
They are formed when the erosion of the sea emphasizes a particular area of a cliff, resulting in the formation of arches attached to these.
They are rocky mounds that have been left over from long processes of marine erosion where at some point there was a cliff or dry land..
They are created by eroding the less hard materials of a cliff.
They are pieces of land joined by isthmus.
They are formed by the accumulation of sediments. They are parallel to the coast and are joined at some point. If it were to be found in another and closed, it would become a lagoon.
In general, thousands of years of marine erosion have resulted in different types of coastlines, such as beaches, bays, dunes, coves and gulfs..
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