The place where the sea (or any other body of water) is in direct contact with a solid surface is called the shore. It is here that there is a constant confrontation of two elements: water and land. Over time, the shores collapse and take on completely new forms.
Abrasion is ... Definition and origin of the term
In the broadest sense, abrasion is a process of mechanical destruction of something. The term itself comes from the Latin word abrasio, which translates as “scraping” or “scraping”.
The term is used in many sciences and spheres of human activity. For example, there is such a thing as tooth abrasion. This is the process of physical abrasion of hard tissues of teeth due to direct contact of their surfaces.
This term can be found immediately in several scientific disciplines - in geology and geomorphology, medicine, gynecology, numismatics, etc. For example, in numismatics, abrasion is the wear of metal coins during their circulation. And in medicine, this concept is understood as irritation of the walls of the stomach due to exposure to potent chemicals.
Coastal abrasion - what is it? Views of the coast
The coastline is heterogeneous, it is constantly being destroyed and modified. The culprits of this are two processes: the surf and gravity. On the other hand, all coastal strips of any water bodies in the world, one way or another, were formed under the continuous influence of waves arising in the same water bodies.
Marine abrasion is a process of destruction of indigenous and loose rocks of the coast. It is logical to assume that it depends on three main factors:
- strength and degree of wave action;
- density and stability of rocks;
- steepness of the coastal slope.
Indeed, the steeper the coastal slope, the more intense it will collapse. And the strength of the waves themselves, of course, also affects the process of marine abrasion.
In modern geomorphology, several main types of coasts are distinguished:
- Abrasion-denudation (formed under the influence of sea waves and slope processes).
- Fiordovye (formed as a result of flooding by the waters of the sea or ocean of glacial valleys).
- Skerry (consist of many small rocky islands separated by narrow straits).
- Estuary (formed as a result of flooding by the sea of estuarine sections of river valleys).
- Rias (formed due to flooding of narrow river valleys in mountainous areas by sea waters).
Abrasive shore and its elements
What is an abrasive beach? And what does he look like?
So they call a special, specific form of relief. In simple words, this is a steep and rather high shore of a reservoir (sea, ocean, lake, artificial reservoir), which is destroyed under the constant influence of the surf. As a result of the work of the waves, he, as it were, retreats toward the land, is "eaten" by the waters of the sea or ocean.
Geomorphologists were able to identify four main elements in the structure of an abrasive shore. It:
- cliff (coastal ledge);
- wave breaking niche;
- bench - abrasion underwater slope;
- accumulative underwater terrace.
In the formation of any abrasive shore, two opposing but complementary processes are involved. This is actually abrasion (destruction by waves of rocks of the coast) and accumulation (accumulation of loose products of this destruction).
In different parts of the world you can see the most beautiful abrasive shores: in England and Scotland, France and Poland, Russia, USA, Australia. For example, on the southern coast of the island of Sicily is a unique natural site - Skala dei Turki. The seashore is composed of sedimentary rock - marl. Under the long-term influence of the waves, these rocky cliffs smoothed out and turned into smooth natural steps of dazzling white color. How it looks can be seen in the photo below.
How are shores destroyed?
The process of forming an abrasive shore begins with the formation of a tiny recess at the base of its slope. Gradually, it grows in size, turning into a large niche. The “language” of rocks that hangs over this niche collapses over time and forms a small coastal ledge - a cliff.
A coastal cliff may consist of pebbles, sand, gravel, and larger clastic material. Sometimes it takes on quite bizarre shapes and outlines. So, on the coast of California there is the city of Mendocino, which is known for its unusual "Beach of round stones" (Bowling Ball Beach). The sea surf gradually destroyed the rocky rocky shore, and the resulting clastic material was turned into the sea to the state of round stone balls. It all looks pretty interesting (see photo below).
In general, the total length of abrasive shores on the planet is about 400 thousand kilometers. On average, annually about 10 billion cubic meters of water from cliffs and benches goes into water bodies m of clastic material.
Abrasion protection
Marine abrasion causes a lot of trouble to many countries of the world. Scientists are constantly trying to develop more effective methods of dealing with it.
Protection from this phenomenon can be either natural or artificial (created by man). For example, the beach acts as an excellent natural remedy against the destructive effects of abrasion. After all, he takes upon himself the main blow of the sea waves, absorbing their energy.
Artificial coastal protection from abrasion consists in the construction of bulk shafts on the inner side of the coast, the construction of powerful concrete walls along the coast. Breakwaters help to cope with the process we are considering. These are long concrete structures that are built perpendicular to the coastline. Their name speaks for itself: the breakwaters, as it were, “cut” the sea waves, significantly reducing their destructive power.