What are dunes in geography. What are dunes and dunes? How are they formed? The highest sand hills in the world

The boundless sea of ​​sand is a familiar landscape for the desert. It is hard to imagine a place less fit for life than this. And yet, even here, animals and people live, accustomed not only to the unimaginable heat, but also to the changeable nature of this wasteland.

And if we talk about the desert, then we should not lose sight of such a phenomenon as a dune. What is a dune, it would seem, is not difficult to imagine. But even he can hide amazing secrets, the knowledge of which is extremely important for survival in the desert.

So, dune - what is it?

To begin with, let's look at the information that the geographical community gives us. So, based on their data, a dune is a huge accumulation of sand, which subsequently forms hills or small mountains. The dune always has a curved shape, somewhat reminiscent of a sickle or a crescent. But how is a dune formed? What is it, and according to what laws does it exist?

In fact, everything is very simple. The dune is formed due to the breath of the wind, which overtakes grains of sand from one place to another. This action is reminiscent of the movement of water in the oceans, with its ripples and waves. And if after the end of the wind the surface of the sea becomes smooth again, then in the desert everything is completely different. When calm comes, everything here freezes in place, as if time has frozen and does not want to move on.

Life in the sandy wasteland

People living in the desert are often forced to lead a nomadic lifestyle. After all, even when their homes are within the same oasis, they still somehow need to get food, resources and medicines. Therefore, from time immemorial, they have been engaged in trade between settlements, making many kilometers of routes through the desert.

That is why they know well what a dune is, and how insidious it can be. Indeed, unlike an ordinary hill, a dune does not stand in one place. Under the influence of strong winds, he wanders from place to place, which greatly complicates the life of trackers. That is why the desert inhabitants from early childhood study the laws by which the dunes move. Otherwise, how can they then explore the expanses of the desert?

Barchans: harsh and a bit dramatic

But how do the inhabitants of the East see the dune? What is a dune for them: a severe enemy or a silent companion on the way? Probably, it all depends on the person himself and on how he looks at the world. After all, some complain about fate, while others accept its challenges, with their heads held high.

The same applies to dunes. Someone sees them as enemies, and someone finds them beautiful. After all, when the sand under your feet is rapidly crumbling down, it seems that the dunes begin to sing. And this song captivates those who gave their hearts to the endless horizons of the desert.

Both dunes and dunes are moving sand hills formed by the wind.

In deserts, on the shores of the seas and large rivers, the wind easily picks up clouds of grains of sand and blows them away. Their flow, flying low above the ground, accumulates in the form of tubercles near various small obstacles - bushes of plants, stones, uneven terrain. Where such winds blow often, heaps of sand grow. It turns out embankments elongated along the wind. On the side from which the wind blows, it makes their slopes gentle, on the opposite side they are steeper, steeper. Often the wind forms dunes not only from sand, but also from clay particles, salt crystals, shell crumbs.

Gone With the Wind

Dune knows no rest. Their tops "smoke" - the wind raises small particles. He drags the larger ones up the gentle slope, throws them over the top, and they fall down the steep side. As a result, the entire hill is moved by the wind further and further. And behind, in its former place, the brought portions of sand begin to settle again, and a new dune is formed. Thus, in vast open spaces, strings of moving hills are formed. Often they close in wide chains. In the Takla Makan Desert (China), three-kilometer dune stripes were observed.

Experts distinguish about a dozen typical forms of sand embankments. For example, where it often changes direction and strength, dunes are formed that look like pyramids. They do not grow sideways, but upwards. In the Sahara, the dunes reach the height of a 100-story skyscraper! And the highest stationary dunes adorn the Badyn-Jaran desert in northern China. The height of some of them reaches 500 m. Soil waters protect them from moving and scattering, which do not allow the sand to dry completely.

The speed of dune movement sometimes exceeds one hundred meters per year, but usually it is much less (10-20 m/year). Along the lower edges of the dunes, air currents are weaker. Plus, from below the sand is fed by the moisture of the underlying soil. Therefore, these edges have time to overgrow with grass with hard, often branched stems and deep roots. Plants slow down the movement of the dune edges, while the middle continues to creep, the dune becomes narrower, but longer. If the winds are not strong and unstable, the dune can be covered with shrubs, trees and turn into a small green hill.

By the way, vegetation is the main difference between dunes and dunes. Those are completely naked, therefore they move faster, and their shape is more bizarre.

Enemies or friends?

Creeping mountains of sand can bring a lot of trouble. They interfere with construction, fill up fields, gardens, forest belts, roads and estates. In the 18th century, a dune invasion in northwestern France completely buried a couple of towns. And in the local village of Sulan, even the bell tower of the local church was covered with sand. True, the dunes gradually went further, and after a hundred years, the buildings were completely freed from sandy captivity.


At the same time, the dunes give a peculiar beauty to many regions and landscapes (for example, the Curonian Spit in the Kaliningrad region). Sand and wind can be grateful to archaeologists - sand mounds bury the ruins of ancient cities, saving them for future excavations. Well, for beach lovers, the dunes provide shelter from the wind and privacy.

What do the dunes sing about

There are dozens of places on Earth where sand hills can not only be seen, but also heard. They make sounds reminiscent of squeaking, grinding, rattling, grumbling of a dog, buzzing of a propeller.

Walking along the coastal dunes, you can hear short melodic whistles under your feet. Another option is the “humming” desert dunes. A vibrating rumble occurs when a sand avalanche falls from high dunes. It happens to spread over 10 km and is heard for up to 15 minutes. At the same time, the legs sometimes feel slight vibrations of the soil.

In ancient times, it was believed that the voices of ghosts and evil local spirits that live in the dunes are heard in the “singing sands”. The phenomenon cannot find a clear scientific explanation so far. Several theories have been developed, but each has its own flaws. One thing is firmly clear: sound arises from the movement of dry, hot grains of sand.

Fans of experiments have experimented with sand more than once. It was even possible to make salt crystals “buzz”. They found that the slightest moisture silences the sand. On the other hand, "silent" sand may sound after washing. It is possible that foreign particles (for example, dust from abrasion of particles) interfere with the "voice".

The clue was sought in the fact that the “singing sands” consist of particles of the same size and, moreover, are very smooth. However, in the experiments, sorted by size and polished sand categorically refused to "beep" or "buzz". In addition, a noticeable part of the sand grains of the humming Sandy Mountain in the Kalahari Desert turned out to be rough and angular.


They tried to explain the phenomenon by the fact that quartz sand grains are easily electrified. But then they found out that the “barking” sands in Hawaii are not made of quartz, but of particles of mollusk shells and microalgae shells.

The area of ​​the sounding dunes of the Earth is sharply reduced: transport, mass tourism, pollution of the natural environment... Will our descendants be able to listen to the "singing" dunes and be surprised at this mysterious voice of nature?

The section is very easy to use. In the proposed field, just enter the desired word, and we will give you a list of its meanings. I would like to note that our site provides data from various sources - encyclopedic, explanatory, word-building dictionaries. Here you can also get acquainted with examples of the use of the word you entered.

The meaning of the word dunes

dunes in the crossword dictionary

Explanatory Dictionary of the Living Great Russian Language, Vladimir Dal

dunes

m. pl. orenb. hilly steppe sands.

New explanatory and derivational dictionary of the Russian language, T. F. Efremova.

dunes

pl. Sandy alluvial hills in deserts and semi-deserts.

Encyclopedic Dictionary, 1998

dunes

DUNES (Turk.)

common name for bare desert sands;

crescent-shaped in terms of accumulation of sands (height up to 150 m), inspired by the prevailing winds; the windward (convex) slope is gentle (5-14°) and long, the leeward (concave) slope is steep (up to 30°) and short, turning into pointed "horns". They move at speeds up to hundreds of meters per year.

dunes

(Turk.), continental dunes of deserts, hills of loose sand, blown by the wind and not fixed by vegetation. Solitary and group B., inspired by dense soil (with an insufficient amount of sand), are usually low (from 0.5 to several m), but over time they can reach a height of more than 100 m. They have characteristic semilunar or crescent-shaped outlines in plan with a long a gentle (5≈14╟) windward slope and a short steep (30≈33╟) lee slope, turning into wind-stretched “horns”. In areas of continuous sand, both simple dune relief forms of small and medium sizes (up to 10–20 m high) and complex, complex ones, where these forms are combined with large ones, with a relative height of up to 200–300 meters or more, are formed. Depending on the wind regime, wind clusters take various forms: dune ridges, longitudinal to the prevailing winds or elongated along their resultant; dune chains transverse to mutually opposite winds; dune pyramids in places of convection of eddy currents, etc. B. not fixed by vegetation can be moved by wind at a speed of tens of cm to hundreds of meters per year. Dune massifs with sparse vegetation often contain large reserves of fresh water. See also Aeolian landforms.

B. A. Fedorovich.

Wikipedia

Dunes (disambiguation)

dunes:

• Dunes - a mobile accumulation of loose sand
• Barkhany - a village, Narimanov district of the Astrakhan region

Examples of the use of the word dunes in the literature.

On top of that, mean dunes, which looked so solid and indestructible, immediately began to crumble under their feet, as soon as one of the friends climbed up to their middle.

Elina and her companions rode through the desert for another eleven days before dunes were replaced by ordinary stony soil.

He stood motionless for another moment, then the monotonous howl of the whirlwind was replaced by a metallic whistle of compressed air blowing through the nozzles, clouds of dust surrounded the stern, green highlights ran into them, mixing with the red light of the sun, and in the roar of unceasing thunder that shook the desert and returned from the rocks with repeated echoes , the ship slowly rose into the air so that, leaving behind a scorched circle, glazed dunes and wisps of fog disappear at increasing speed into the purple sky.

He tossed aside his oxygen device, took a hesitant breath, but as the cold pre-dawn air filled his lungs, he walked faster, trying not to think of anything but this hike through dunes into which he now and then fell through knee-deep.

To his right, then climbing on dunes, then slipping into the inter-dune hollows, his shadow rushed.

Having passed a high dune, which, under its sands, kept the secret of an ancient settlement, the commander turned the car to the right, to where, like an army ready for an offensive, countless people lined up in orderly rows. dunes, similar to the crescent of the new moon.

Iranian and scimitar-like nomads dunes Karakums and Kyzylkum.

Here one could only shoot and eat and trudge through dunes- until the end of days.

dunes, dunes and dunes, as well as an old caravan road covered in sand in some places.

He stood, getting used to the darkness again, and began to distinguish the nights that were disappearing into oblivion. dunes, and looking closely, I saw at the limit of visibility very faint lights on the horizon or on something that served as a horizon in the darkness.

Golden dunes stretched in all directions, ankle-deep in the sand, and around - not a single trace.

The desert was everywhere, sand, dunes, occasionally breaking teeth of rocks, from which it could be concluded that the planet, in any case, does not consist entirely of sand, below, under it, there is also solid rock.

The man looked at the sun, putting his hand to his eyes with a visor, and the woman looked around her and under her feet with the air of a man who expected to see something completely different, and not what appeared to her eyes - dunes and rare rocks, resembling hotels that once stood here no more than a lizard that ran between the legs of a man, looked like a Nile crocodile that had long disappeared from the face of this planet.

dunes

DUNES (Turk.), mobile sand dunes not fixed by vegetation of various shapes (lunar, thyroid, sickle-shaped) with a convex windward side and a steeper leeward side. A specific component of biotopes of desert and semi-desert ecosystems. They are widely found in Australia, Central Asia (in the south-west of Kazakhstan), etc. They are often formed under the influence of human activity.

Ecological encyclopedic dictionary. - Chisinau: Main edition of the Moldavian Soviet Encyclopedia. I.I. Grandpa. 1989

Dunes are mobile landforms in sandy deserts, consisting of wind-blown sand. In sandy ecosystems they are accumulators of fresh water.

Ecological dictionary. - Alma-Ata: "Science". B.A. Bykov. 1983

• barochory
• Biogenic migration of elements

See what "Dunes" are in other dictionaries:

Sands moving in ridges or ridges in the steppes. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. Dunes in the steppe areas. moving sands in the form of ridges or ridges. Dictionary of foreign words included in ... ... Dictionary of foreign words of the Russian language

- (Turkic), 1) the general name of the bare sands of deserts; 2) crescent-shaped in terms of accumulation of sands (height 15,150 m), inspired by the prevailing winds; the windward (convex) slope is gentle (5 14sh) and long, leeward (concave) steep (up to 30sh) ... ... Modern Encyclopedia

- (Turk.) 1) the general name of the bare sands of deserts; ..2) crescent-shaped in terms of accumulation of sands (height up to 150 m), inspired by prevailing winds; the windward (convex) slope is gentle (5 14 .) and long, leeward (concave) steep (up to 30 .) and ... Big Encyclopedic Dictionary

Husband, pl., orenb. hilly steppe sands. Dahl's Explanatory Dictionary. IN AND. Dal. 1863 1866 ... Dahl's Explanatory Dictionary

dunes- Asymmetric sandy hills of different heights (from 110 to 150200 m), crescent-shaped and common in deserts and semi-deserts. [Glossary of geological terms and concepts. Tomsk State University] Topics geology, geophysics… Technical Translator's Handbook

dunes- (Turkic), 1) the general name of the bare sands of deserts; 2) crescent-shaped in terms of accumulation of sands (height 15,150 m), inspired by the prevailing winds; the windward (convex) slope is gentle (5 14 °) and long, leeward (concave) steep (up to 30 °) ... ... Illustrated Encyclopedic Dictionary

Ov; pl. (unit dune, a; m.). [Kazakh. barkhan]. Sandy alluvial hills in deserts and steppes, not fixed by vegetation. ◁ Dune, oh, oh. Used sands. * * * dunes (Turk.), 1) the general name of the bare sands of deserts; 2) sickle-shaped in terms of ... encyclopedic Dictionary

dunes- DUNES, ov, mn (ed dune, a, m). Small hills in deserts and steppes, having gentle slopes, consisting of wind-blown sand, not fixed by vegetation. The dunes stood on the sides, soft, loose, wavy (B. Lavrenev) ... Explanatory dictionary of Russian nouns

- (Turkic) continental dunes of deserts, hills of loose sand blown by the wind and not fixed by vegetation. Single and group B., inspired by dense soil (with an insufficient amount of sand), are usually low (from 0.5 to several ... ... Great Soviet Encyclopedia

See Dunes... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

Books

• The Greatest Natural Phenomena, Collection. From time immemorial, the unknown, little-studied and difficult to explain makes people think about the secrets of our world, encourages scientists to scientific research and expeditions, and amateur enthusiasts - ...

The meaning of the word Barkhany according to Efremova:
Barkhans - Sandy alluvial hills in deserts and semi-deserts.

Barchans in the Encyclopedic Dictionary:
Barkhans - (Turk.) - 1) the general name of the bare sands of deserts; ..2) crescent-shaped in terms of accumulation of sands (height up to 150 m), inspired by the prevailing winds; the windward (convex) slope is gentle (5-14 .) and long, leeward (concave) - steep (up to 30 .) and short, turning into pointed "horns". They move at speeds up to hundreds of meters per year.

The meaning of the word Barkhany according to Dahl's dictionary:
dunes
m. pl. orenb. hilly steppe sands.

The meaning of the word Barkhany according to the dictionary of Brockhaus and Efron:
dunes- cm. Dunes.

Definition of the word "Dunes" according to TSB:
dunes(Turk.)
continental dunes of deserts, hills of free-flowing sand, blown by the wind and not fixed by vegetation. Solitary and group B., inspired by dense soil (with an insufficient amount of sand), are usually low (from 0.5 to several m), but over time they can reach a height of more than 100 m. They have characteristic semilunar or crescent-shaped outlines in plan with a long a gentle (5-14°) windward slope and a short steep (30-33°) lee slope, turning into wind-stretched "horns".
In areas of solid sands, both simple dune landforms of small and medium sizes (up to 10-20 m high) and complex, complex ones are formed, where these forms are combined with large ones, with a relative height of up to 200-300 meters or more. Depending on the wind regime, wind clusters take various forms: dune ridges, longitudinal to the prevailing winds or elongated along their resultant; dune chains transverse to mutually opposite winds; dune pyramids in places of convection of eddy currents, etc. B. not fixed by vegetation can be moved by wind at a speed of tens of cm to hundreds of meters per year. Dune massifs with sparse vegetation often contain large reserves of fresh water. See also Aeolian landforms.
B. A. Fedorovich.
Dune relief in the Sahara.

Dune relief in the Sahara.

Scheme of classification of dune (desert bare) landforms of sands in accordance with the wind regime.
wind mode. I - trade wind with a pronounced predominance of one or close directions (shown by an arrow); II - monsoon-breeze with a seasonal change of opposite winds; III - interference with seasonal change of mutually perpendicular winds; IV - convection with vectors of different directions of similar intensity.
Relief forms of dune sands. A. simple forms of small and medium sizes (single, group and continuous fields): 1 - thyroid B.; 2 - thyroid B. with a funnel; 3 - sickle-shaped symmetrical B.; 4 - asymmetric B.; 5 - longitudinal wind group B.; 6 - dune ridge longitudinal to the wind; 7 - dune
"a train"; 8 - dune jagged ridge; 9 - dune ridge; 10 - dune trihedral ridge; 11 - group snowstorms and dune chains with elongated horns with a sharp predominance of winds of one direction; 12 - the same, with a smaller difference in the intensity of opposite winds; 13 - the same, with a small difference in the intensity of opposite winds; 14 - wedge-shaped small B.; 15 - wedge-shaped large B.; 16 - fine-meshed (circular) B.; 17 - large-mesh (circular) B.; 18 - pyramidal B. B - complex forms (consisting of large forms, combined with small and medium ones); 19 - longitudinal dune ridge with diagonal ribs; 20 -
"whale back" with diagonal ribs of complex dune chains; 21 - dune rampart with a ridge of dune pyramids; 22 - complex double B. with "scales" of dune chains of different categories of sizes; 23 - complex dune chains; 24 - cranked double dune ridges and chains; 25 - crossed complex dune ridges and chains; 26 - round dune swellings; 27 - complex dune pyramids, a - ridges and slopes of shedding sand; b - gentle slopes of sand.