Abrasion is ... Sea abrasion. Types and elements of coasts

The place where the sea (or any other body of water) is directly in contact with a solid surface is called the shore. It is here that there is a constant confrontation between two elements: water and land. Over time, the banks collapse and take 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 abrasion of teeth. 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. So, in numismatics, abrasion is the wear and tear of metal coins in the course of their circulation. And in medicine, this term is understood as the irritation of the walls of the stomach due to the action of strong chemical preparations.

Abrasion of the coast is what is it? Types of coasts

The coastline is not homogeneous, it is constantly destroyed and mutated. The culprits of this are two processes: sea surf and gravity. On the other hand, all the coastal strips of any water bodies in the world, one way or another, were formed under the continuous influence of waves arising in these water bodies.

Sea abrasion is the process of destruction of the indigenous and loose rocks of the shore. 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 be destroyed. 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).
• Fjordovye (formed as a result of flooding of the glacial valleys by the sea or ocean).
• Scherny (composed of many small rocky islets, separated by narrow straits).
• Limannye (formed as a result of the flooding of the estuary areas of river valleys).
• Riasovye (formed due to inundation of the narrow river valleys in the mountainous areas by the sea waters).

Abrasive shore and its elements

What is an abrasive coast? And what does he look like?

This is the name of the specific, specific shape of the relief. In simple terms, it is a steep and fairly high shore of a reservoir (sea, ocean, lake, artificial reservoir), which is destroyed under the constant impact of the surf. As a result of the waves, it seems to retreat toward the land, "eaten up" by the sea or ocean.

Geomorphologists were able to distinguish four basic elements in the structure of the abrasive shore. It:

• Cliff (coastal ledge);
• Wave surfacing;
• Bench-abrasion underwater slope;
• Underwater accumulative terrace.

In the formation of any abrasive shore, two opposite but complementary processes are involved. This is proper abrasion (destruction by waves of rocks of the shore) 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 south coast of the island of Sicily there is a unique natural object - Scala dei Turki. The sea shore here is composed of a sedimentary rock - marl. Under the long-term influence of waves, these rocky cliffs were smoothed out and turned into smooth natural steps of dazzling white. How it looks, you can see in the photo below.

How are the banks collapsing?

The process of formation of abrasive coast begins with the formation of a tiny indentation at the base of its slope. Gradually it increases in size, turning into a major niche. The "tongue" of rocks that hangs over this niche, eventually collapses and forms a small coastal ledge - the cliff.

Coast cliff can consist of pebbles, sand, gravel and larger detrital material. Sometimes it takes on rather bizarre shapes and shapes. So, on the coast of California is the city of Mendocino, which is known for its unusual "Beach of round stones" (Bowling Ball Beach). The sea surf gradually destroyed the hard rocky coast, and the formed clastic material was turned into the sea to the condition of round stone balls. It all looks pretty interesting (see the photo below).

In general, the total length of abrasive shores on the planet is about 400 thousand kilometers. On average, about 10 billion cubic meters per year are taken from the cliffs and benches into the reservoirs. M clastic material.

Protection against abrasion

Sea abrasion is a lot of trouble for many countries in the world. Scientists are constantly trying to develop more effective methods to combat it.

Protection from this phenomenon can be both natural and artificial (created by man). So, for example, the beach is an excellent natural remedy for the destructive effects of abrasion. After all, he takes on the main impact of sea waves, absorbing their energy.

Artificial protection of shores from abrasion consists in the construction of bulk shafts from the inner side of the shore, the erection of powerful concrete walls along the coast. Help to cope with the process we are considering and breakwaters. These are long concrete structures that are built perpendicular to the shoreline. Their name speaks for itself: wavebreakers seem to "cut" the sea waves, significantly reducing their destructive power.