MARINE EROSION: TYPES, EFFECTS, CAUSES - CULTURE VOCABULARY - 2025

The marine erosion is the wear of the land of the coast and sediment removal from the sand dunes by the 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 one area softer than another in a reduced area, formations such as bridges, tunnels or natural pulars can occur.

How does marine erosion occur?

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 is not so involved in erosion.

Waves

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 it becomes a hangover or backwash, which is when it acts as a blanket 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.

Ocean currents

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.

Currents also produce a parallel motion when waves slant the shores.

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.

Types

Hydraulic starters

They are produced when waves collide with little 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.

Abrasion

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 coastlines, cliffs and abrasion platforms.

Corrosion

The salts present in the sea dissolve many materials, mainly the limestone rock located in its interior, which will later become 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.

Biological process

In this case, the animals are responsible for erosion. The sea contains animals that eat the rock (lithophagi) and others that transport the dissolved limestone rock into the sea to form coral reefs.

Vegetables also have an influence by staying in rock crevices, thus facilitating their breakdown.

Causes

There are two main causes of marine erosion:

Attraction of the Moon

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 Sun's gravity and, above all, the Moon's gravity in maritime waters.

The Moon attracts the nearest masses of water towards it, 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. Lunar gravity pulls the entire Earth, not just the sea, only the Earth is rigid and does not bulge.

Solar gravity plays a secondary role: despite being more intense, it is at a greater distance.

Depending on the phases of the Moon and the point of terrestrial translation, the behavior of the tides varies and, by extension, maritime erosion occurs.

Storms

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 their force during heavy rains.

At this time, cement blocks of more than 1000 metric tons have been moved.

An immediate and devastating factor is the earthquakes that produce tsunamis, whose effect can change the terrain where it hits in a matter of hours.

Effects edit

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:

Cliffs

They are rocky or steep vertical slopes. They are formed by the impact of the waves and are the result of the erosion of the eroded rock.

This rock gives way to rocks resistant to erosion, these are usually sedimentary rocks.

Abrasion platforms

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.

Marine bows

They are formed when the erosion of the sea emphasizes a particular area of ​​a cliff, resulting in the formation of arches attached to them.

Faraglioni

They are rocky mounds that have been left over from long processes of marine erosion where at some point there was a cliff or land.

Sea caves

They are created by eroding the less hard materials of a cliff.

Peninsulas

They are pieces of land joined by isthmus.

Littoral arrows

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.

References

1. Marine erosion. Retrieved on January 27, 2018 from Enciclopedia.us.es.
2. The Moon and its influence on the tides. Retrieved on January 27, 2018 from Astromia.com.
3. Coastal erosion. Retrieved on January 27, 2018 from en.wikipedia.org.
4. Causes and effects of coastal erosion. Retrieved on January 27, 2018 from getrevising.co.uk.
5. Coastal erosion: its causes, effects and distribution. Retrieved on January 27, 2018 from Nap.edu