home Fishing methods Coastal landforms. See what "coastal landforms" are in other dictionaries

Coastal landforms. See what "coastal landforms" are in other dictionaries

Before proceeding to the characterization of coastal marine processes and the relief forms they create, let us dwell on the definition of some concepts.

Coastline (cut line) - the line along which the horizontal water surface of the sea (or lake) intersects with land. Since the level of reservoirs does not remain constant, the coastline is a conditional concept applied relative to some average long-term position of the reservoir level.

Coast- a strip of land adjacent to coastline, the relief of which is formed by the sea at a given average level of the reservoir.

underwater coastal slope- the coastal strip of the seabed, within which the waves are able to carry out active work (wash out the bottom, move sediments).

coastal zone includes a coast and an underwater coastal slope.

Depending on the nature (morphology) of the coast, the coast is distinguished: high(for example, the coast of the Kola Peninsula) and low (north coast Caspian Sea); dismembered(the coast of the Black Sea between Crimean peninsula and the mouth of the Danube) and aligned(Black Sea coast between Gelendzhik and Sochi); deep, having significant slopes of the underwater coastal slope with predominant development abrasive(destructive) processes (Black Sea coast south of Novorossiysk), shallow, characterized by small angles of inclination of the underwater coastal slope, with a predominance of material accumulation processes (shores of the Northern Caspian).

In the coastal zone there is a complex of forces that determine its morphological appearance. These are the ebbs and flows and the currents associated with them; in non-tidal seas with shallow shores - surge phenomena and the currents they cause; tsunami- marine gravity waves of great length, arising from underwater earthquakes; constant sea currents; the activity of organisms; the activity of rivers that form a special type of banks ( potamogenic shores). However, the main acting factor that determines the morphology and dynamics of the coast are the waves and the wave currents associated with them.

Waves. The wind, acting on the water surface, causes oscillatory movements of water in its surface thickness. Water particles begin to make orbital movements in a plane perpendicular to the sea surface, and the movement along these orbits occurs in the direction of the wind. Distinguish deep sea waves and shallow waves. Since wave movements fade with depth, the division of sea waves into these categories is carried out according to the criterion: the depth of the sea is greater or less than the penetration depth of wave movements. At a depth equal to half the wavelength or more than it, the wave oscillations, and consequently, their impact on the bottom of the reservoir, are damped.

In the sea wave, they distinguish height h, length L, period T, propagation velocity v and elements like crest and wave trough, front and back slopes, front and wave beam(Fig. 19.1). The time during which a water particle describes a complete orbit is called a period, and the value obtained by dividing the wavelength by its period is called propagation speed.

Rice. 19.1.

h- height; L - length; 1 - wave crest; 2 - hollow; 3 - rear slope of the wave; 4 - front slope of the wave. Arrows indicate wind direction

Rice. 19.2.

The parameters of the waves depend on the strength of the wind and its duration, on the nature of the underwater coastal slope, on the length of the wave acceleration. Like the energy of a stream, the total energy of waves can be expressed by the formula: E \u003d l / 8pgh2L, where E- wave energy, R- density of water, g - acceleration of gravity, h- wave height, L- wavelength. Given that png change within insignificant limits, we can say that the wave energy is proportional to the length and square of the wave height.

Shallow water waves as opposed to waves high seas act on the bottom (on the underwater coastal slope) and experience its effects themselves. As a result, they spend energy on the transformation of the bottom topography, on the transfer of detrital particles lying on the bottom. Waves of the open sea consume energy only to overcome internal friction and to interact with the atmosphere.

The more energy is expended by waves when passing over the underwater coastal slope, the less it reaches the coastline. As a result of interaction with the bottom, when passing over shallow water, the waves change their profile and become asymmetric: the front slope becomes steeper, and the back slope flattens out. External asymmetry corresponds to the asymmetry of the orbits that arise in shallow water waves, along which water particles move. Orbits from round become elliptical, and the ellipses themselves are irregular, flattened from below (see Fig. 19.2). Accordingly, the equality of orbital velocities is lost. The velocities of movement directed towards the coast (ie, when passing through the upper part of the orbit) become greater than the velocities of the reverse movement (along the lower part of the orbit). This ratio of velocities is of fundamental importance for understanding the processes of sediment movement and relief formation in the coastal zone.

The increase in the steepness of the front slope of the wave reaches a critical value above a depth equal to the height of the wave. It becomes vertical and even overhanging. There is a collapse of the crest of the wave, as a result, the wave movement of water is replaced by a fundamentally new type of movement - surf stream, or coasting. The very destruction of the wave is called surf.

A surf stream is formed from a mass of water formed when a wave breaks. It runs up the coastal slope, and the direction of the flow approximately coincides with the direction of the wave that caused it, but still noticeably deviates from the original under the influence of gravity (Fig. 19.3). The speed of the surf flow decreases as it moves away from the place of origin, i.e. from where the wave breaks. The deceleration of the flow is associated with the expenditure of energy to overcome gravity, to overcome friction on the surface along which it runs, to move and process sediments, and also to lose part of the water mass for infiltration into the soil.

Rice. 19.3.

The point where the speed of the surf stream drops to zero is called the top of the clasp. From here, the mass of water not yet wasted on infiltration flows down the slope in the direction of the greatest slope. This "branch" of the surf stream is called reverse surf flow, or rollback.

Consequently, the upper and lower boundaries of the coastal zone are determined by the boundaries of the wave action on the coast, namely: the lower boundary is located at a depth equal to half the wavelength, i.e. the isobath at which wave deformation begins, and the upper one is determined hem line, formed by a set of surf splash peaks. According to the available data on the length of ocean waves, reaching 350 m, the lower boundary of the underwater coastal slope in the oceans can be traced at depths of up to 150 m, in the seas - up to 50 m.

To understand wave processes on the shores of the seas, it is necessary to have an idea of refraction. refraction is called the turn of the wave front as it approaches the coast, and this process is carried out in such a way that the wave front tends to take a position parallel to the coast. On a flat coast, with full refraction, this is what happens, but on a rugged one, due to the fact that each segment of the front tends to be parallel to the corresponding segment of the coast, there is, as it were, a compression of the front near the capes and its stretching in the bays. As a result, there is a concentration of wave energy near capes and scattering in the concavities of the coastal contour (Fig. 19.4). The result of this is the “cutting” (abrasion) of capes, the accumulation of material in concavities (bays) and, as a result, the alignment of the coast, and in essence, the alignment of the energy of waves approaching the coast.

It should be noted that the actual orbits along which water particles move during waves are somewhat open due to the pulsating (uneven) effect of wind on the water surface. Due to the openness of the orbits, not only the waveform moves, but also the actual movement of the water mass in the direction of wave propagation, i.e. towards the coast. This creates a rise in sea level near the coast compared to the level position in the open sea. Level skew causes formation compensatory flows.

Rice. 19.4.

(according to V.P. Zenkovich):
- 1 - wave fronts; 2 - rays of waves;
- 3 - the base of the underwater slope

When the waves approach at a right angle to the shore with a gentle underwater slope, the first breaking of the waves occurs still at a considerable distance from it. The mass of water accumulating near the shore is dammed up by the “living wall” of the surf until it finds an outlet in some area where this “wall” is somewhat lower. Then the masses of water break through from the coast towards the sea, forming a discontinuous flow(Fig. 19.5). Rip currents, due to their "stormy" nature, develop speeds of up to several meters per second and are able to carry out from the coastal strip to the outer zone of the underwater coastal slope a large number of disturbed sediments. This is one of the reasons for the leakage of sediments from the coastal strip of the coastal zone.

As the waves approach shallow shore at an acute angle, the outflow of excess water occurs along the coast. As a result, a alongshore wave current(Fig. 19.5, B). It also has significant velocities and, along with proper wave motions, is an important means of moving sediment along the coast.

As the waves approach deep coast the outflow of excess water from the shore is carried out by the bottom current directed from the shore towards the sea, - bottom countercurrent(Fig. 19.5, A). It also contributes to the removal of detrital material from the coastal strip to the outer coastal zone.

From what has been said, it is obvious that wave movements and the wave currents caused by them lead to the movement of sediments perpendicular to the coast - this is called transverse movement of sediments, or along the coast alongshore movement of sediments. Both of these factors lead to the formation of specific landforms within the coastal zone.

Rice. 19.5.

BUT-bottom countercurrent; B- coastal current:

(lakes, rivers), called the coast.

The banks are subdivided depending on their steepness (sloping, steep) and the nature of the materials that compose them (silty, sandy, pebbly, rocky). From the side of the water area, a strip of the seabed adjoins the shore, which is constantly affected by wave movements of water. This strip is called the underwater coastal slope.

The coast and the underwater coastal slope together form coastal zone of the sea, within which the complex interaction of the lithosphere, hydrosphere, atmosphere and biosphere is constantly carried out. This zone is characterized by the variability of landforms and their various combinations within even small areas. Work sea water manifested in the destruction of the coast - abrasion, as a result of which they retreat inland, as well as in the deposition of destruction products - accumulation, which leads to a change in the underwater relief of the coastal zone and to the formation of new types of coasts. The shores formed mainly as a result of the destructive work of the waves are called abrasion, and the shores created by the deposition of sediments are called accumulative.

The main factor in the formation of abrasion shores is the destructive work of breaking waves, as a result of which a depression is formed at the base of the slope - wave-cutting niche. Over time, this niche deepens more and more, the overhanging parts of the slope fall into the sea, breaking up into a mass of debris, with the help of which breaking waves continue to further destroy the coastal ledge.

The creative work of the sea is expressed in the accumulation off the coast of materials thrown by the sea (sand, pebbles, shells of marine animals, etc.). Pebbles and sand on the surface of the abrasion platform constantly move within it under the influence of the surf. As a result, landforms of accumulative origin are created.

As a result of repeated changes in the depth of the ocean during glacial and interglacial epochs, peculiar landforms formed in the coastal zones of the seas, which are called ancient coastlines. They may sometimes be located on land and correspond to a position of the sea higher than at present. Ancient coastlines matching more low level are now flooded by the sea.

Elevated coastlines are expressed as sea terraces. These are steps stretched along the coast.

In each terrace stand out: the surface of the terrace; ledge; edge; back seam. They fix the position of the ancient coastline.

Depending on the structure, there are:

Accumulative terraces, that is, completely composed of coastal marine sediments;
Abrasive terraces, which are composed only of bedrock;
Basement terraces having a root base covered with marine sediments.

To identify the history of the development of the coast, the so-called terrace spectra, which allow comparison of different parts of the coast and contain information about neotectonic movements.

Shore types (according toD. G. Panov)

(a – rias, b – fjord, c – skerry, d – firth, e – Dalmatian, f – watt (1 – watts, 2 – runoff troughs), g – thermal abrasion, h – coral, i – volcanic).

Literature.

Smolyaninov V. M. General geography: lithosphere, biosphere, geographical envelope. Teaching aid / V.M. Smolyaninov, A. Ya. Nemykin. - Voronezh: Origins, 2010 - 193 p.

(lakes, rivers), called the coast.

The coast and the underwater coastal slope together form coastal zone of the sea, within which the complex interaction of the lithosphere, hydrosphere, atmosphere and biosphere is constantly carried out. This zone is characterized by the variability of landforms and their various combinations within even small areas. The work of sea water is manifested in the destruction of the coast - abrasion, as a result of which they retreat inland, as well as in the deposition of destruction products - accumulation, which leads to a change in the underwater relief of the coastal zone and to the formation of new types of coasts. The shores formed mainly as a result of the destructive work of the waves are called abrasion, and the shores created by the deposition of sediments are called accumulative.

As a result of repeated changes in the depth of the ocean during glacial and interglacial epochs, peculiar landforms formed in the coastal zones of the seas, which are called ancient coastlines. They may sometimes be located on land and correspond to a position of the sea higher than at present. The ancient coastlines corresponding to the lower level are now submerged by the sea.

Elevated coastlines are expressed as sea terraces. These are steps stretched along the coast.

In each terrace stand out: the surface of the terrace; ledge; edge; back seam. They fix the position of the ancient coastline.

Depending on the structure, there are:

Accumulative terraces, that is, completely composed of coastal marine sediments;
Abrasive terraces, which are composed only of bedrock;
Basement terraces having a root base covered with marine sediments.

To identify the history of the development of the coast, the so-called terrace spectra, which allow comparison of different parts of the coast and contain information about neotectonic movements.

Shore types (according toD. G. Panov)

(a – rias, b – fjord, c – skerry, d – firth, e – Dalmatian, f – watt (1 – watts, 2 – runoff troughs), g – thermal abrasion, h – coral, i – volcanic).

Literature.

Smolyaninov V. M. General geography: lithosphere, biosphere, geographical envelope. Teaching aid / V.M. Smolyaninov, A. Ya. Nemykin. - Voronezh: Origins, 2010 - 193 p.

Coast- this is the boundary of land and sea, where their interaction takes place. It occurs within a relatively wide band called coastal zone. This zone includes the surface part of the coast and the underwater coastal slope.

Forces influence the coastal zone: sea waves; wave currents and tidal phenomena. The following also take part in the formation of the coasts: rivers connecting the deltaic coasts; tectonic movements; living organisms.

Clastic material in the coastal zone, moved by waves and surf, is commonly called sea deposits. The accumulation of sediments in the zone of the surf flow is commonly called beach. Usually the beach is composed of larger sediments than the underwater coastal slope. Near the wave breaking zone, the largest detrital material accumulates, since the maximum flow velocities are at the beginning of its movement.

Beaches are distinguished according to morphological features. full and partial profile.

Full profile beach is formed if there is free space in front of the formed sediments. Then the beach takes the form of a coastal shaft, which has a sloping and wide sea slope and a steeper slope facing the coast. If the beach is formed at the foot of the ledge, then sloping beach or partial beach, with one slope facing the sea.

During the transverse movement of sediments, various underwater and coastal accumulative forms arise. it underwater ramparts, which are accumulative forms composed of sandy material and stretched along the coast parallel to each other. Usually there are 2-3 shafts, less often 5-6 shafts. Their height is from 1 to 4 meters with a length from several hundred meters to several kilometers.

The origin of underwater shafts is associated with the partial destruction of waves or the so-called turning. In this case, the shafts lose part of the energy and the material carried by them is deposited on the bottom in the form of an underwater shaft. The zone of partial destruction of waves with a shallow bottom near the coast can be quite wide. They call her burrowing zone. A large number of underwater swells is due to the fact that waves of different magnitudes experience scaling at different depths. Underwater swells are formed in places of the underwater slope, where the waves of a certain intensity are partially destroyed. Beaches, coastal and underwater ridges are elementary accumulative forms. Larger accumulative formations include coastal bars or barriers.

Shore bars composed of material of bottom origin, usually shell and coral sand. Οʜᴎ stretch for tens and hundreds of kilometers along low-lying sea coasts and usually separate coastal waters from the sea, which are commonly called lagoon. The foot of the sea bars are located at a depth of 10-20 m, and above the water they rise by 5-7 m, sometimes up to several tens of meters. Such a high height is achieved due to the dunes. Bars are widespread and are found on 10% of the shores of the world's oceans. It can be assumed that the formation of bars is associated with an increase in the level of the ocean in the postglacial period. At the same time, the surfaces of the flooded accumulative plains turn out to be too sloping and the waves carry them towards the coast. large masses sand. Excess transported sediments fall out during movement and form an underwater bar, which becomes an obstacle for sediments coming from the underwater coastal slope. Their deposition on the sea side of the bar leads to its expansion in width. At the same time, the bar also grows in height due to the accumulation of sediments on the ridge and the general movement of the bar to shallower depths. It can be assumed that the formation of coastal or island bars is associated with a change in the level of the world ocean in recent times.

Longitudinal sediment movement. When waves approach at an oblique angle to the shore, longitudinal, or alongshore movement of sediments. Due to wave vibrations, sediment particles travel along a zigzag path and travel a certain distance along the coast. The surf stream, running up to the beach, at the beginning retains the direction of the wave, then deviates more and more from it under the influence of gravity. The reverse flow escapes in the direction of the greatest slope. It describes an asymmetric trajectory resembling a parabola and moves sediment particles along the coastline. The speed of such movement depends on the angle of wave approach to the shore. In this case, its optimal value is 45 °. Under certain conditions, there is a mass movement of sediments on the beach and on the underwater coastal slope. Such their movement in one direction over a long period of time, for example, for a year, is commonly called a sediment flow. The flow is characterized by power, capacity and saturation.

Flow power is the amount of sediment, ĸᴏᴛᴏᴩᴏᴇ actually moves along the coast in a year. capacity- it is customary to call the amount of sediment, ĸᴏᴛᴏᴩᴏᴇ waves are able to move. If the power is equal to the capacitance, then this means that all the energy of the waves is spent only on transport. Neither coast erosion nor sediment deposition occurs in this case. For this reason saturation flow should be called the ratio of power to capacity. If this ratio is less than 1, then the flow is not saturated. In this case, part of the energy free from the work of transporting the material will be directed to erosion of the coast. If the flow capacity is less than the sediment inflow to a given area, we can talk about an increase in the intensity of sediment inflow over the flow capacity. As a result, part of the material stops moving and is deposited, forming accumulative forms.

Accumulative Forms during Longitudinal Movement of Sediments. With a decrease in the angle of wave approach to the shore, the flow capacity decreases and material accumulation begins. This creates: accumulative forms of filling the contour of the coast. This category includes various accumulative underwater terraces at the tops of the bays. Accumulative braids, which are formed when the flow goes around the ledge of the coast. In this case, the wave front spreads and its energy decreases. The braids are attached to the shore only by their root part, and their growing end remains free. For this reason, such braids are called free accumulative forms. If the coast is protected from the sea by a cape, then at the entrance to the bay a closing form is formed, which is commonly called a bay.

Abrasion. Abrasion is usually called the destructive work of the sea. It is mechanical, chemical and thermal.

Mechanical abrasion- this is the destruction of rocks that make up the coast under the influence of surf waves and rock fragments carried by waves and surf.

Chemical abrasion- destruction of rocks due to their dissolution by sea water.

Thermal abrasion- destruction of the coast, composed of frozen rocks, or ice, as a result of the warming effect of sea water.

With a steep slope of the coastal slope, the waves come to the shore with a large supply of energy. They have a direct impact on the area adjacent to the coastline. For this reason, a recess is formed here, which is commonly called rippling niche. When it deepens, the cornice collapses. The mass of rock entering the water accelerates the destruction of the shore even more. The process of collapse of the cornice is repeated several times, which leads to the formation of a vertical ledge, that is abrasion cliff or cliff. In front of the cliff, a platform slightly inclined towards the sea is developed, called bench. The bench starts at the very foot of the cliff and continues below sea level. The expansion of the bench during abrasion leads to a flattening of the profile and attenuation of the processes of destruction of the coast.

Shoreline alignment. The destruction of the coasts and the formation of accumulative coastal forms lead to the alignment of the coastline. Its initial outlines are currently determined by the penetration of sea waters into relief depressions after the retreat of the glacier. Such coasts are called ingressive. Among them are:

1. Fjord (fjord) shores formed during the flooding of glacial valleys. fjords- narrow and long winding bays (Norway, Canada, New Zealand).

2. skerry shores, which were formed during the flooding of low glacial plains. Skerries- these are small rocky islands, which are flooded sheep's foreheads, separated by narrow straits.

3. rias shores, arising from the flooding of river valleys in mountainous countries. Rias are narrow winding bays. For example, Sevastopol Bay.

4. Limannye shores formed during the flooding of the river valleys of the coastal plains. The bays resulting from this - estuaries. ( S.-Zap. Black Sea).

5. Dalmatian-type coasts, which arose during the flooding of folded structures with a strike close to the general direction of the coast. At the same time, bizarre archipelagos of islands are formed, stretched along the coast.

6. Banks of fault-block lobed dismemberment, which are formed during the flooding of tectonic depressions of grabens (Greek coast of the Aegean Sea).

All types of banks are in different stages of alignment, which is associated with the unequal nature of the initial dissection and different geological structure. At the same time, some sections of the coast turned out to be leveled, others are leveled, and the third ones acquired even greater dissection in the course of leveling. This happened due to the formation of bays or irrigation in place of rocks more susceptible to erosion, as well as during the formation of trailing accumulative forms.

Some coasts retain their original dissection. This applies to the rias and fjord coasts, as well as to the coasts of tectonic dissection, composed of strong igneous rocks. Such shores are called shores, not changed by the sea. Their development proceeds mainly under the influence of slope processes. They can be called denudation, and with a great influence of the sea - abrasion-denudation.

Coasts of the tidal seas. Seashores are affected not only by waves, but also by tides. At the same time, the tides on the deep shores increase the abrasion, since with increasing depth near the coast, the waves act more energetically on the cliff. The foot of the cliff on such shores is at the level of the high tide. At low tide, only part of the suspended material is carried away by the ebb current. As a result, accumulative forms are formed near the shore, which are called droughts or watts. Gradually, the drying surface becomes higher than the level of the tides, vegetation settles on it and a soil cover forms - marches appear.

Τᴀᴋᴎᴍ ᴏϬᴩᴀᴈᴏᴍ, the accumulative activity of the tides generally leads to an increase in land. Within coastal shallow waters, underwater accumulative forms can form: sand ridges and sand waves.

sand ridges- These are large linear forms up to several kilometers long and 1-2 km wide. Their height is up to 20 m. They are located along the coast in the direction tidal currents.

sand waves- these are formations that have arisen on the slopes of sandy ridges and are oriented frontally with respect to the direction of tidal currents. Their sizes range from several hundred meters to several kilometers in length and up to several meters in height. Οʜᴎ resemble enlarged signs of wave ripples.

coral shores and islands. In the formation of sea coasts on the coasts of tropical seas, some marine reef building organisms which absorb lime from sea water. When they die, they form coral or reef limestone. Accumulative forms built from such limestone are called coral reefs.

There are the following types of coral structures:

- fringing or coastal reefs;

- barrier reefs;

- ring or intralagoonal reefs.

fringing reefs these are underwater coral-limestone terraces adjacent to the shore. Their outer side is covered with living coral colonies. The reef surface is called reef flat. With distance from the outer zone, this surface is more and more covered with a sediment cover of gravel and sand. Near the coast, it is bordered by a sand and gravel beach. The thickness of the fringing reef, on tectonically stable shores, usually does not exceed 50 m, which is associated with the habitat of reef-forming corals. Coral polyps live in symbiosis with a single-celled green algae that needs good light.

barrier reefs these are coral-limestone ridges, remote from the coast for considerable distances. Barrier reefs are many times thicker than fringing reefs. It has been established that they arise during the tectonic subsidence of their outer edge. The largest such reef is the Great Barrier Reef, stretching along the northeastern margin of Australia for more than 2300 km. If a barrier reef forms around a small subducting island, it will transform into a ring reef or atoll. At the same time, a coral lagoon is formed inside the atoll, in which intralagoonal reefs can appear. In most cases, they look like columns, or giant pedestals, randomly scattered inside the lagoon. Merging with each other, the columns form large-sized formations, which are called banks. Coral islands are often found in tropical seas. Usually they are located on accumulative forms formed due to the activity of sea waves and consisting of coral deposits - sand, gravel, pebbles, and sometimes blocks of reef limestone.

As a result of repeated changes in the depth of the ocean during glacial and interglacial epochs, peculiar landforms formed in the coastal zones of the seas, which are called ancient coastlines.Οʜᴎ can sometimes be located on land and correspond to the position of the sea higher than at present. The ancient coastlines corresponding to the lower level are now submerged by the sea.

Elevated coastlines are expressed as sea terraces. These are steps stretched along the coast. In each terrace stand out: the surface of the terrace; ledge; edge; back seam.Οʜᴎ fix the position of the ancient coastline.

Given the dependence of the detuning, they distinguish:

1. Accumulative terraces, that is, completely composed of coastal marine sediments;

2. Abrasive terraces, which are composed only of bedrock;

3. Basement terraces having a root base covered with marine sediments.

To identify the history of the development of the coast, the so-called terrace spectra, which allow comparison of different parts of the coast and contain information about neotectonic movements.

Marine coastal landforms - concept and types. Classification and features of the category "Marine coastal landforms" 2017, 2018.

Coastal landforms

abrasive and accumulative. Abrasive forms: steep, often sheer coastal ledge, or cliff, wave-cut niche and coastal, or abrasion, platform; surf karrs, miniature quest-like beds, gigantic cauldrons. Coastal accumulative forms are of great variety. According to morphological features, they are divided into three types: joined- accumulative surface formations adjoining the coast along their entire length; free- narrow alluvial strips of land adjacent to the coast at only one end, and then departing from it at an ever-increasing angle; closing- connected to the shore both by their root part and by the growing end. According to the conditions of formation and the composition of the constituent material, accumulative coastal landforms are divided into beaches, beach festoons, coastal ridges, underwater ridges, bars, spits, bay-bars and tombolos, or brims. Beach- this is a cloak of loose material from pebbles, gravel, sand and shell detritus covering the abrasion platform. beach festoons- a row of rollers, parallel to the coastline, is created by the surf at the sea margin of the beach. Coastal swells- a two-sided full-profile beach, composed of sand, pebbles or shells. Underwater shafts- sandy linear, forming a series of shafts, appear parallel to the coast and isobath lines by transverse movements along coastal sediments caused by wave movements. bars- underwater shafts brought to the surface. braids- free linear accumulative forms of simple and complex structure, straight and crescent-shaped in plan, connected to the shore at one end. Peresyp- linear accumulative forms blocking bays. tombolo- narrow linear, usually sandy forms, tying the islands to the coast.

Geography. Modern illustrated encyclopedia. - M.: Rosman. Under the editorship of prof. A. P. Gorkina. 2006 .

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