Research project "sand, its properties, use and production at home." Summary of nodes for the middle group “where does sand come from” Formation of sand in nature

Sand is a material that consists of loose stone grains with a grain diameter of 1/16 mm to 2 mm. If the diameter is more than 2 mm, it is classified as gravel, and if less than 1/16, then as clay or silt. Sand is mainly created by the destruction of rocks, which accumulate together over time to form grains of sand.

Sand weathering process

The most common method of sand formation is weathering. This is the process of transforming rocks under the influence of factors such as water, carbon dioxide, oxygen, temperature fluctuations in winter and summer. Most often, granite is destroyed in this way. The composition of granite is quartz crystals, feldspar, and various minerals. Feldspar, when in contact with water, disintegrates faster than quartz, which allows granite to crumble into fragments.

Sand denudation process

As rocks collapse, they move from higher elevations downward under the influence of wind, water, and gravity. This process called denudation.

Under the influence of the processes of weathering, denudation and accumulation of minerals over a long period of time, one can observe the leveling of the land topography.

Sand fragmentation process

Fragmentation is the process of crushing something into many small fragments, in our example it is granite. When the crushing process occurs quickly, the granite is destroyed even before the feldspar is destroyed. Thus, the resulting sand is dominated by feldspar. If the crushing process occurs slowly, then the content of feldspar in the sand decreases accordingly. The process of rock fragmentation is influenced by the flow of water, which enhances fragmentation. As a result, we have sands with low feldspar content on steep slopes.

Sand grain shape

The shape of the sand grains starts out angular and becomes more rounded as they are polished by abrasion during transport by wind or water. Quartz sand grains are the most resistant to wear. Even a long stay near the water, where it washes it, is not enough to thoroughly roll the angular quartz grain. Recycling time is on the order of 200 million years, so a quartz grain that first eroded from granite 2.4 billion years ago may have gone through 10 to 12 cycles of burial and re-erosion to reach its current state. Thus, the degree of roundness of an individual quartz grain is an indirect indicator of its antiquity. Feldspar grains can also be rounded, but not as well, so sand that has been moved several times is mostly quartz.

The influence of the ocean and wind on the process of sand formation

Sand can be formed not only by weathering, but also by explosive volcanism, as well as as a result of the impact of waves on coastal rocks. As a result of the influence of the ocean, the sharp corners of the rocks are polished and over time they become crushed. This way we get the sea sand we are used to. During a storm in the cold season, water that gets into the cracks of the rocks becomes ice, which leads to splitting. Thus, over time, sand is also obtained. Nothing would have happened without the intervention of the wind. The wind wears grains of sand on the rocks and scatters them.

Application area of ​​sand

Sand surrounds us everywhere. It is most used in construction. By combining it with water and cement we get a concrete solution. Sand is added to dry building mixtures in the manufacture of artificial stone and tiles. Sand has even found use in alternative medicine for the prevention of radiculitis and problems with the musculoskeletal system. No children's playground is complete without a sandbox. Sand is also widely used for making glass; backfilling into sandblasting machines to clean the surface from rust and various types of corrosion; for filling football fields; as soil for an aquarium; .

Details about the origin of quartz sand can be emphasized from the article: A large selection of fractionated quartz sand can be found on our website.

Sand is, on the one hand, such a familiar and simple material to everyone, and on the other hand, it is so mysterious and enigmatic. You look at him and cannot take your eyes off.
I'm into an art called sandart. This special kind drawing-animation, but instead of paints they use dry sand. During classes, I began to wonder why he was like that.
If you touch, you calm down. You want to look at it, run your fingers through its small grains. Watch how it pours from hand to hand. Sand is so pleasant to the touch.
In his research work I decided to expand my knowledge about the material with which I work. The work is relevant and can be applied in school as additional material to classes.

Purpose of the study: Study sand: its origin, types, uses. Conduct an experiment on creating sand at home.

Tasks:
1. Find out what sand is?
2. Get to know different types of sand
3. Find out where sand is used?

Research hypothesis: If the sand is chemical compound, is it possible to conduct a chemical experiment to make it at home using scrap materials?

Study plan:
1.Familiarize yourself with information about sand
2. Prepare everything necessary for the experiment
3. Conduct an experiment
4.Draw conclusions

What is sand?
Everyone can imagine what sand is. WITH scientific point From a perspective, it is still a bulk material of inorganic origin, consisting of many small grains of sand or fractions, sedimentary rock, as well as artificial material consisting of rock grains
Sand is made from small particles of minerals that are part of rocks, so various minerals can be found in sand. Quartz (a substance - silicon dioxide or SiO 2) is mainly found in sand, since it is durable and there is a lot of it in nature.
Sometimes sand is 99% quartz. Other minerals in the sand include feldspar, calcite, mica, iron ore, as well as small quantities of garnet, tourmaline and topaz.

1.1. How and from what was sand formed?
Sand is what is left of rocks, boulders, and ordinary stones. Time, wind, rain, sun and time again destroyed mountains, crumbled rocks, crushed boulders, crushed stones, turning them into billions of billions of grains of sand ranging in size from 0.05 mm to 2.5 mm, making sand out of them. Sand is formed where rocks are subject to destruction. One of the main places where sand formation occurs is the seashore.
The second most common form of sand is calcium carbonate, such as aragonite, which was created over the last one and a half billion years various forms life such as corals and shellfish.
What about sand in deserts? Sand from the shore is carried by the wind inland. Sometimes so much sand is moved that an entire forest can be covered by sand dunes. In some cases, desert sand is formed as a result of the destruction of mountain ranges. In some cases, on the site of the desert there was once a sea, which, having retreated thousands of years ago, left sand here.

Classification by characteristics
Sands are classified according to the following criteria:

Density;

Origin and type;

Grain composition;

Content of dust and clay particles,
including clay in lumps;

Content of organic impurities;

The nature of the grain shape;

Content of harmful impurities and compounds;

Strength.

River and sea sands have rounded grains. Mountain sands are acute-angled grains contaminated with harmful impurities.

Types of sand
Natural sand
river sand- This is sand that is mined from the bottom of rivers and is characterized by a high degree of purification. It is a homogeneous material with the absence of foreign inclusions, clay impurities and pebbles. It is purified naturally - by the flow of water.
The main advantage of river sand is that it is sand, and not a sand mixture containing clay, earth, or stone particles. Thanks to long-term natural exposure, sand grains have a smooth oval surface and a size of approximately 1.5-2.2 mm.
River sand is a fairly high-quality, but at the same time quite expensive building material. River sand is extracted using special equipment - dredgers. This does not harm the environment at all, but on the contrary helps to clean river beds. The coarsest river sand is mined at the mouths of dry rivers.
The color palette of mined sand is quite diverse, from dark gray to bright yellow. The reserves of this building material in nature are practically inexhaustible.
Everyone knows that in some regions of the Russian Federation
river sand is a source of gold mining

Sea sand- this is sand that contains (in comparison with other types of sand) the smallest amount of foreign impurities. The purity of sea sand is determined by the place of its extraction, as well as the use of a two-stage cleaning system to remove foreign inclusions. The first stage of sand cleaning takes place directly at the site of its extraction, and the second stage - within special production sites. Considering the high quality of sea sand, it, without exaggeration, can be used in any construction work.

Quarry sand is a natural material mined in open pits. This sand has a fairly high content of clay, dust and other impurities. Quarry sand is cheaper than river sand, which makes it widely used. Depending on the cleaning method, it is divided into seeded and washed quarry sand.
Quarry washed sand- This is sand extracted from a quarry by washing with a large amount of water, as a result of which clay and dust particles are washed out of it. Sand can include various types of impurities, such as stones, earth, clay. Mining is carried out using excavators in large open pits. Quarry sand is usually divided according to the size of its constituent grains. It can be fine-grained (particles up to two millimeters in size); medium-grained (particles ranging in size from two to three millimeters); coarse-grained (particles ranging in size from two to five millimeters). Quarry sand has a coarser structure compared to river sand.
Quarry seeded sand- This is sifted sand extracted from a quarry, cleared of stones and large fractions.

Construction sand
Unlike natural varieties, artificial sands are produced using specialized equipment by mechanical or chemical action on rocks.
In turn, artificial sands are divided into subtypes of sedimentary and volcanic origin.
Construction sand can be used as a universal base for the production of a variety of building materials and cement mortars. Such a wide scope of application is primarily due to one of the specific qualities of this material: porosity.
Artificial sand has many advantages compared to natural sand, but there are also disadvantages, namely: in addition to the relatively high price, artificially produced sand may have higher radioactivity.
Perlite sands- are produced through heat treatment from crushed glasses of volcanic origin, called perlites and obsidians. They are white or light gray in color. Used in the manufacture of insulation elements.
Quartz. Sands of this type are also commonly called “white” because of their characteristic milky white hue. However, the more common varieties of quartz sand are yellowish quartz, which contains a certain amount of clay impurities.
In comparison with sands of natural origin, this material is advantageously distinguished by its homogeneity, high intergranular porosity, and therefore dirt holding capacity.
Quartz sand is mined in quarries. Quartz sand is used to create sand-lime bricks and silicate concrete, fillers for polyurethane and epoxy coatings, which gives them strength and high wear resistance.
Due to its versatility and high quality, this type of sand is widely used in various industries, including water treatment systems, glass, porcelain, oil and gas industries, etc.
Marble. Is one of the most rare species. Used to make ceramic tiles, mosaics, and tiles.

Application of sand
Widely used in building materials, for the reclamation of construction sites, for sandblasting, in the construction of roads, embankments, in residential construction for backfilling, in the improvement of courtyard areas, in the production of mortar for masonry, plastering and foundation work, used for concrete production . In the production of reinforced concrete products, high-strength concrete, as well as in the production of paving slabs and curbs.
Fine construction sand is used to prepare solutions.
Sand is also used in glass production, but only one type is quartz sand. It consists almost entirely of silicon dioxide (quartz mineral). The purity and uniformity of sand make it possible to use it in the glass industry, where the absence of the slightest impurities is important.
Less pure quartz sand is used in plastering (internal and external) finishing works. Using it in the production of concrete and brick allows you to give the resulting product the desired shade.
Construction river sand is quite widely used in various decorative (mixed with various dyes to obtain special structural coatings) and finishing works of the finished premises. It also acts as a component of asphalt concrete mixtures, which are used in the construction and laying of roads (including for the construction of airfields), as well as in water filtration and purification processes.
Quartz sand is used for the manufacture of welding materials for special and general purposes.
Agriculture: Sandy soils are ideal for crops such as watermelon, peaches, nuts, and their excellent characteristics make them suitable for intensive dairy farming.
Aquariums: It is also an absolute must for saltwater reef aquariums, which emulates the environment and consists mainly of aragonite corals and shellfish. Sand is non-toxic and completely harmless to aquarium animals and plants.
Artificial reefs: sand can serve as the basis for new ones
reefs.Beaches: Governments move sand to beaches where
tides, eddies or deliberate changes coastline destroy the original sand.
Sand is Sand Castles: Forming sand into castles or
other miniature buildings are popular in cities and on the beach.
Sand Animation: Animation Filmmakers Use
sand with front or back illuminated glass. That's how I do it too.

Practical part
We were faced with a task: is it possible to make silicon dioxide at home?
To conduct the experiment I will need:

silicate glue;

vinegar 70%;

container 2 pieces or molds;

syringe;

apron, gloves.

It is necessary to observe safety precautions - vinegar is an acid. We conduct the experiment in a room with open windows, because the vinegar smells strong. You cannot bend over, smell or try anything. We put on protective equipment.
I take silicate glue. Carefully pour about 1/3 into the container.
Then I take the vinegar and pour it into another container. About the same 1/3.
I use a syringe to remove vinegar from the container. I take about 10 ml.
Very carefully pour vinegar into the glue.
A reaction occurs. The glue turns into a gel and hardens. Using a stick, thoroughly mix the glue and vinegar.
I got Silicon Dioxide (SiO2) - a substance consisting of colorless crystals with high strength, hardness and refractoriness.
In nature, silicon dioxide is quite widespread: crystalline silicon oxide is represented by minerals such as jasper, agate, rock crystal, quartz, chalcedony, amethyst, morion, and topaz.
You can mix vinegar, glue and food coloring of any color. The result is colored silicon dioxide.

European scientists initially became acquainted with sands far from deserts - on the banks of rivers, moraines and oceans. The sands brought by rivers are exposed from under the water only during low water and climatic conditions Europe is almost never covered. Ancient river sands in European countries They are distributed in small strips, overgrown with forests, and therefore river sands in Europe do not cause much harm and are not dangerous to anyone.

The sands on the shores of the oceans are a different matter. Storm waves and tidal waves throw more and more masses of sand onto the shore each time. The winds blowing over the ocean easily pick up the dried sand and carry it deep into the continent. It is not easy for vegetation to establish itself on such constantly blowing sand. And then some more goats will come from the village and attack, trample, or even uproot the fragile shoots. And it happened more than once that fishermen’s villages, and even large villages and towns, found themselves buried under sand dunes on the coast of Europe. Centuries passed, and only the top of the high spire of the old Gothic cathedral, sticking out of the sands, reminded people of the destruction of the village that had once occurred.

Almost the entire western Atlantic coast of France has been covered with sand for centuries. Many areas of the northern coast of East Germany and the Riga seaside also suffered from them. The raging Atlantic, Northern and Baltic Sea and the advancing sands they generated were the most formidable picture of nature familiar to the inhabitants and scientists of Europe.

And naturally, when the Europeans found themselves in the deserts and became acquainted with their huge sand massifs, like the sea, they involuntarily believed that the desert sands were the brainchild of the sea. This is how “ original sin"in desert exploration. The usual explanation was applied to the sands of the Sahara, which supposedly was the bottom of a recent ocean, and to the sands Central Asia, which were supposedly covered in ancient times by the inland Hanhai Sea.

Well, what can we say about our deserts, where the Caspian Sea actually flooded spaces that rose 77 meters above its current level?

And, however, it is Russian researchers who have the honor of overthrowing these incorrect views, according to which sea waves were considered the only powerful creator of sand on earth.

In this regard, many of our researchers of the 19th century were on the right track, when they first began to study various regions of Central and Central Asia. Among them, first of all, we must name Ivan Vasilyevich Mushketov, a pioneer of geological study Central Asia, and his student Vladimir Afanasyevich Obruchev, who made many difficult and long journeys throughout Central and especially Central Asia. These two researchers, combining geologists and geographers, showed that, along with truly sea sands, sands of other origins are widely developed in deserts.

I.V. Mushketov believed that, in addition to sea and river sands, in many desert areas, including Kyzyl-Kum, sands are formed during the destruction of various rocks in a sharply continental desert climate. One of the merits of V. A. Obruchev was the substantiation by a number of facts of the position that the sands of another empty Central Asia - Kara-Kum - were formed due to sediments of the ancient Amu Darya, which previously flowed from the area of ​​​​the city of Chardzhou directly to the west to the Caspian Sea.

He also proved that in the deserts of eastern Central Asia, in Ordos and Ala Shan, the main creator of sand is the destructive forces of the atmosphere.

The arguments of these scientists were logical and convincing, but they had too few facts to fully resolve the questions of the origin of each mass of sand in the deserts.

During the Soviet period, much more research was devoted to a comprehensive study of sands. As a result, it was possible to establish the sources and accumulation paths of a wide variety of sand massifs, although it was not always easy to reconstruct their biography.

In western Turkmenistan alone we counted twenty-five sand groups of different origins. Some of them were formed due to the destruction of ancient rocks of different age and composition. This group of sands is the most diverse, although it occupies a relatively small area. Other sands turned out to be brought by the Syr Darya to the area of ​​the modern Khiva oasis. Still other sands were brought by the Amu Darya and deposited on the plains, now located at a distance of 300 - 500 kilometers from the river. The fourth sands were carried out to the sea by the Amu Darya, the fifth, very special sands, accumulated in the sea due to shells crushed by waves sea ​​mollusks. The sixth sands were formed in the now waterless, but formerly lacustrine Sarykamysh depression. They contain a mass of calcareous and flint skeletons of microorganisms.

Sea of ​​sand. From the northern Aral Sea region to the south, along the eastern shores of the Aral Sea, through the entire Kyzyl-Kum desert and further, through the expanses of the Kara-Kum to Afghanistan and the foothills of the Hindu Kush, and from east to west from the foothills of the Tien Shan to the shores and islands of the Caspian Sea stretches a huge, covered waves of the sea, above which only isolated islands rise. But this sea is not blue, its waves do not splash, and it is not filled with water. The sea shimmers in red, yellow, gray, and whitish tones.

Its waves, in many places immeasurably higher than the breakers and swells of the ocean, are motionless, as if frozen and petrified in the midst of an unprecedented storm that covered colossal spaces.

Where did these huge accumulations of sand come from and what created their motionless waves? Soviet scientists have studied the sands well enough to now be able to answer these questions definitely.

In the Aral Kara-Kums, in the Big and Small Barsuki sands and on the eastern shores of the Aral, the sands have a dull white color. Each grain is rounded and polished, like the smallest grain. These sands consist almost exclusively of quartz alone - the most stable of minerals - and a small admixture of smaller black grains of ore minerals, mainly magnetic iron ore. These are old sands. How long were they life path. It is difficult to find the remains of their ancestors now. Their lineage dates back to the destruction of some ancient granite ridges, the remains of which are now preserved on the surface of the earth only in the form of the Mugodzhar Mountains. But since then, these sands have been redeposited many times by rivers and seas. This was the case in the Permian, and in the Jurassic, and in the Lower and Upper Cretaceous. The sands were last rewashed, sorted and redeposited at the beginning of the Tertiary period. After this, some layers turned out to be so tightly welded with silicic acid solutions that the grains merged with cement, forming a hard, oily quartzite, pure as sugar. But even this strongest stone is affected by the desert. Loose layers of sand are blown away, hard stones are destroyed, and again the sands are redeposited, this time not by sea or river water, but by the wind.

Our research has shown that during this last “air travel” of sands, which began in Late Grecian times and continued throughout Quaternary period, they were transported by the wind from the northern Aral Sea region, along the eastern shores of the Aral Sea up to the shores of the Amu Darya, and possibly further to the south, that is, approximately 500 - 800 kilometers.

How did Red Sands happen? It is not for nothing that the Kazakhs and Karakalpaks call their largest sandy desert Kyzyl-Kum, that is, Red Sands. Its sands in many areas actually have a bright orange, reddish-red, or even brick-red color. Where did these layers of colored sand come from? From the destroyed mountains!

The ancient mountains of the Central Kyzyl-Kum are now low, rising 600 - 800 meters above sea level. Millions of years ago they were much higher. But for the same amount of time they are exposed to the destructive forces of wind, hot sun, night cold and water. Remnant hills, like islands, rise above the surface of the Kyzyl-Kum. They are surrounded, like trains, by stripes of gently sloping gravelly alluvial deposits, and then sandy plains stretch beyond.

In the Middle Ages of the earth's history, both the Mesozoic and the beginning of the Tertiary period, the climate here was subtropical and red earth soils were deposited on the mountain slopes. The destruction of the remnants of these soils, or, as geologists say, “ancient weathering crusts,” is what colors the Kyzyl-Kum sands in red tones. But the sands of this desert do not have the same color everywhere, since their origin is different in different areas. In places where ancient sea sands were subjected to winding, the sands of these plains are light yellow. In other areas, these sands are yellowish-grayish - these are ancient sediments of the Syr Darya. Take a look at the diagram on page 64, and you will see that we were able to trace these sediments both in the southern, central and western parts of the desert. In the south of Kyzyl-Kum, their sands are dark gray and they were brought by the Zeravshan River, and in the west of this desert the sands are bluish-gray and contain a lot of mica sparkles - they were brought here by the Amu Darya in one of the standards of its wanderings. Thus, the history of the Kyzyl-Kum is far from simple, and the biography of their sands is perhaps more complex and diverse than most other deserts in the world.

How were Black Sands formed? . The most southern desert USSR - Kara-Kuma. This name - Black Sands - was given to them because they are heavily overgrown with dark saxaul bushes and the horizon in many places darkens like the edge of a forest. In addition, the songs here are dark - grayish.

In those interridge depressions where the wind reveals previously fresh sands, their color is steel-gray, sometimes bluish-gray. These are the youngest sands - baby sands in the history of our planet, and their composition is very diverse. 42 different minerals can be counted in them under a microscope. Here, in the form of small grains, there are also garnets and tourmalines, familiar to many from necklaces and rings. Large plates of shiny mica, grains of quartz, pink, greenish and cream grains of feldspars, black-green grains of hornblende sand are visible to the eye. These grains are so fresh, as if they had just ground and washed the granite. But where the wind has managed to blow away the sands, their color changes, taking on a grayish-yellow color. And at the same time, the shape of the grains of sand slowly, gradually begins to change: from the angular shape characteristic of young river sands, it increasingly takes on the rounded shape of the so-called “aeolian” sands blown by the wind.

The composition of the Kara-Kum sands, the shape of their grains, the good preservation of low-stable minerals, their gray color, the conditions of occurrence and the nature of the layering indisputably indicate their river origin. But the question is, what kind of river can we be talking about if the Kara-Kums begin in the south from the very foot of the Kopet-Dag, and the nearest large river- Amu Darya - flows at a distance of 500 kilometers? And where can such a quantity of sand come from in the river to cover a huge desert - more than 1300 kilometers long and 500 kilometers across?

Every time I visited different areas of the deserts of Central Asia, I took samples of their sands and submitted them for microscopic analysis. These studies showed that the Kara-Kums were indeed deposited by the Amu Darya, and partly, in its southern part, by the Tedzhen and Murghab rivers (see map on page 69). The composition of the sands of these rivers, carried directly from the mountains, turned out to be exactly the same. as well as in the desert areas they created, lying a hundred kilometers from the current channels of the Murgab and Tedjen and 500-700 kilometers from the modern Amu Darya. But, one wonders, where does the mountain rivers such a huge amount of sand? To get an answer to this question, I had to get to the area where the Amu Darya originated - in the highlands of the Pamirs.

Mountain sand tract. In 1948, I had the opportunity to visit the Pamirs. And here, among mountain ranges and inaccessible rocky cliffs, almost a thousand kilometers from sandy deserts, I came across a small tract, lost in the mountains, which turned out to be a genuine natural laboratory for the formation of sands.

The Nagara-Kum tract, which we called by consonance “The Highland Sands Tract,” is located at the junction of three intersecting valleys, at an altitude of 4-4.5 thousand meters above sea level. One of the valleys stretches in the meridional direction, and the others in the latitudinal direction. These valleys are not particularly long, their width does not exceed 1 - 1.5 kilometers, but they are deep. The flat, undivided bottom of the valleys is not indented by traces of water flows or ancient channels. And that is why, perhaps, the contrast between the smooth and flat bottoms of the valleys and the steep dissected rocky, bare slopes of the mountains is so striking. It seems as if someone has cut deep and wide corridors in the mountains.

Everything indicated that these valleys, geologically relatively recently, were the bed of powerful glaciers sliding down from the snow-capped mountains. And the smoothed, unweathered rocks of the slopes of the amphitheater, located in the eastern part of the latitudinal valley, indicated that they had recently been buried under a layer of firn snow.

A number of data suggested that when the glaciers disappeared, lakes took over the valleys. However, now in this cold mountain kingdom there is too little precipitation, so little that even in winter the snow does not cover the area completely. Therefore, over time, the lakes also disappeared.

In the neighboring valleys, powerful ice dams do not melt even in summer. Here, around the tract, the peaks, higher than Kazbek and Mont Blanc, blacken against the background of a clear blue sky - they are almost not covered with snow in the summer, but sometimes there is little of it in the winter.

We were in Harapa-Kuma during the warmest time of the year - mid-July. During the day, when there was no wind, the sun burned so hard that the skin on our faces (and we had been in Kyzyl-Kum for a month before) was cracking from burns. During the day in the sun it was so hot that I had to take off my sheepskin coat, jacket, and sometimes even my shirt. But this was extremely rarefied air in the highlands, and as soon as the sun set and its last rays disappeared behind the mountain peaks, it instantly became cold. Temperatures dropped sharply and were often well below freezing throughout the night.

The significant altitude of the area, dry thin air and cloudless skies lead to extremely sharp temperature changes.

The transparent, rarefied air of the highlands almost does not prevent the sun's rays from heating both the earth and the rocks during the day. At night, intense radiation is emitted from the earth, heated during the day, back into the atmosphere. However, the rarefied air itself hardly heats up. It is equally transparent to both sunlight and night rays. It heats up so little that it was enough for a cloud to pass during the day or the wind to blow, and it immediately became cold. This sharp change in temperature is perhaps the most characteristic and, in any case, the most active climatic factor high mountain areas.

It is also important that at these altitudes night frosts occur almost every day in summer, and if the stone does not crack due to rapid cooling, then water will finish the job. It seeps into the smallest cracks and, freezing, tears them apart and expands more and more.

The rocks of the eastern slopes of the tract are composed of rounded blocks of coarse-grained gray granite porphyries with well-cut greenish feldspar crystals up to 4-5 centimeters long. The mountain slopes formed by these rocks appear at first glance to be a grandiose accumulation of large moraine boulders, a heap of perfectly round glacial boulders rising above the plain. And only the contrast between the steep piles and the table-smooth valley bottoms, where there is not a single such boulder, makes us more cautious about the assumption that these are glacial boulders.

Having carefully looked at the slopes of the tract, we discovered an amazing thing. Many boulders of gray granite porphyry turned out to be dissected by white stripes of veins consisting of only feldspars - the so-called aplites. It would seem that aplite veins should be located in the boulders brought by the glacier in the most random manner. But why is it absolutely clear that the vein in one boulder is, as it were, a continuation of the vein in another boulder? Why, despite the accumulation of boulders, do aplite veins maintain a single direction and structure along the entire slope, although they intersect tens and hundreds of granite blocks?

After all, no one would be able to diligently lay all these boulders in such an order, strictly making sure not to change the direction of the veins. If a glacier had brought them in, it would certainly have piled up the boulders in the most chaotic manner, and the aplite veins could not have had the same direction in neighboring boulders.

I examined the large round blocks for a long time until I was convinced that many of them were only half-separated from the mountain, like a lump on the lid of a porcelain teapot. This means that these are by no means glacial boulders, but the result of destruction in place of bedrock, from which, over the course of many centuries, nature produced these blocks, or, as geologists call them, spherical weathering units under the influence of sudden changes in temperature. This was also evidenced by the fact that many of the balls had shells peeling off from them, which is typical for processes of mechanical destruction - peeling of rocks.

Granite round timbers, the most varied in size, from 20-30 centimeters to 2-3 meters in diameter, were half buried under a layer of debris and sand formed during the peeling of granite, crumbling from them. These decomposition products turned out to be mineralogically so fresh that the sand grains retained their original appearance; They had not yet been touched by either chemical decomposition or abrasion, and sharply cut crystals of feldspars - a mineral that is chemically the least stable - lay here in the sand, shining in the sun with completely fresh surfaces of the faces.

Many of these blocks crumbled into grains at the very light touch. The entire area provided clear evidence of the strength, power and inevitability of the processes of rock destruction that change and shape the earth's surface over thousands of years.

“Hard as granite” - who doesn’t know this comparison! But under the influence of sunlight, night cold, freezing of water in cracks and wind, this hard granite, which has become synonymous with strength, crumbles into sand under a light pressure of the fingers.

In high-mountain regions, the process of temperature destruction proceeds so quickly that the chemical decomposition of minerals does not have time to affect the decay products at all. The destruction is happening so intensely that almost half of the mountain slopes are already covered with scree and sand.

Often break down here strong winds pick up the smallest decay products of granites and blow out all the dust and sand from them. Dust is carried by air flow far beyond the boundaries of the tract; sand, heavier than dust, is dumped here, in all those places where the wind force decreases due to obstacles encountered.

Over time, a sand bank formed along the entire meridional valley for 13 kilometers. Its width ranges from 300 meters to one and a half kilometers. In some places it is quite flat, smoothed, covered with herbaceous vegetation. To the north, at the intersection of valleys, where the sand is open to latitudinal winds blowing in opposite directions, the shaft is completely bare and the sand is collected in several dune chains parallel to each other.

These chains are high, up to 14 meters, their slopes are steep, the ridges constantly change their shape, obeying the blowing wind, and the wind blows from the east, then from the west.

Bare, flowing, high and steeply upturned sands, the burning sun and the “smoking” ridges of dunes - all this involuntarily transported us to the hot deserts of Asia.

But the mountain sand tract lies in the kingdom of permafrost. Around the dunes, everywhere you look, are the tops of the ridges, covered with eternal snow and sparkling ice. And in the valleys lying a little lower, there were huge white patches of thick ice, formed from the freezing of spring waters in winter.

The most powerful accumulation of sand in the tract is located at the southern intersection of the valleys. The winds blow the strongest here.

Reflecting in all directions from the surrounding steep slopes, the winds experience powerful turbulence. The relief of the sands therefore turns out to be the most complex and most upheavy. The dune chains either scatter in different directions, or merge with each other, forming huge nodes of pyramidal uplifts, rising tens of meters above the depressions.

The mass of these clean, wind-blown sands covers an area of ​​only 14.5 square kilometers in the tract, but nevertheless the thickness of these sand accumulations is quite large, about one and a half hundred meters.

Having experienced these turbulences, the wind rushes further to the east. Rising to the nearby pass, air currents lift the sand and pull it along the slope. The sand stretches in the direction of the prevailing winds in a strip tapering towards the east. This strip stretches up almost 500 meters and goes from the main massif of sands not along the lowest and widest main valley, but in a straight line to the pass, while climbing a fairly steep slope.

So, high in the mountains of the “Roof of the World” and “Foot of the Sun” - the snow-capped Pamirs - there was a corner of the sandy desert! A corner in which nature carries out the entire process of sand formation and development from beginning to end! First, the emergence of igneous rocks to the surface, their destruction by temperature fluctuations, the formation of scree, its crushing into sand grains and, finally, powerful piles of wind-blown sand. And not only winnowed, but also raised by him into dune pyramids the height of a twenty-story building, assembled into a sandy relief typical of deserts!

All these processes took place over a relatively short period of time on a geological scale. However, the strength and power of these processes are such that everything that takes millennia in the deserts was accomplished literally ten times faster in the mountain sands.

It is important, however, that this destruction of rocks and their transformation into sand is not an exceptional phenomenon, but, on the contrary, is very typical for all dry high-mountain regions. On the greatest highland in the world - Tibet - there are many such sandy tracts. In the Pamirs and Tien Shan, sands less often accumulate into massifs due to relief conditions, but they are formed there constantly and continuously for several million years. Lake Kara-Kul, located in the Pamirs in the permafrost region, is bordered on the east by continuous sand. And almost every grain of sand in these highlands, formed under the influence of sudden changes in temperature, melting and freezing of water, soon becomes the property of a scree, and then a mountain stream. This is why rivers in the highlands carry gigantic amounts of sand onto the foothill plains. This is where the Amu Darya gets up to 8 kilograms of sand during floods, and on average it carries 4 kilograms of sand in every cubic meter of water. But there is a lot of water in it, and in just one year it brings a quarter of a cubic kilometer of sediment to the shores of the Aral Sea. Is this too much? It turned out that if we take the duration of the Quaternary period to be 450 thousand years, consider that during this period the Amu Darya carried out the same amount of sand, and mentally distribute it in an even layer over all those areas where the mighty Amu wandered during this time, then the average thickness only its Quaternary sediments would be equal to three quarters of a kilometer. But sand was carried out by the river before, in the second half of the Tertiary period. That is why it is not surprising that in its former mouths, in southwestern Turkmenistan, oil wells penetrate this layer of sand and clay to a depth of 3.5 kilometers.

Now it is clear to us that most of the submontane sandy deserts of Asia are the creation of the highlands. These are the Kara-Kums, which are a consequence of the destruction of the high-mountain Pamirs. These are many areas of Kyzyl-Kum, formed as a result of the destruction of the Tien Shan. These are the sands of the Balkhash region brought from the Tien Shan by the Ili River. This is the greatest sandy desert the world of Taklamakan, the sands of which were brought by rivers from the Himalayas, Pamirs, Tien Shan and Tibet. This is the great Indian Thar Desert, created by the sediments of the Indus River flowing from the Hindu Kush.

Sharp temperature changes in deserts and highlands destroy rocks and create sand. Above are flaky sandstone layers in Western Turkmenistan. Below are dune sands in the Nagara-Kum tract in the Pamirs, formed from the destruction of granites. (Photo by the author and G.V. Arkadiev.)

The ancient Greek philosopher-mathematician Pythagoras once puzzled his students by asking them the question of how many grains of sand there are on Earth. In one of the tales told by Scheherazade to King Shahryar during 1001 nights, it is said that “the armies of the kings were countless, like grains of sand in the desert.” It is difficult to calculate how many grains of sand there are on Earth or even in the desert. But you can quite easily determine the approximate number of them in one cubic meter of sand. Having calculated, we find that in such a volume the number of grains of sand is determined by the astronomical figures of 1.5-2 billion pieces.

Thus, the comparison of Scheherazade was at least unsuccessful, since if the fairy-tale kings needed as many soldiers as there are grains in just one cubic meter of sand, then for this they would have to call the entire male population under arms globe. And even this would not be enough.

Where did countless grains of sand come from on Earth? To answer this question, let's take a closer look at this interesting breed.

Vast continental spaces of the Earth are covered with sand. They can be found on the coasts of rivers and seas, in the mountains and on the plains. But especially a lot of sand has accumulated in deserts. Here it forms mighty sandy rivers and seas.

If we fly in an airplane over the Kyzylkum and Karakum deserts, we will see an immense sand sea (Fig. 5). Its entire surface is covered with mighty waves, as if frozen “and petrified in the midst of an unprecedented storm that engulfed colossal spaces.” In the deserts of our country, sand seas occupy an area exceeding 56 million hectares.

Looking at sand through a magnifying glass, you can see thousands of sand grains of different sizes and shapes. Some of them have a round shape, others have irregular outlines.

Using a special microscope, you can measure the diameter of individual grains of sand. The largest of them can be measured even with a regular ruler with millimeter divisions. Such “coarse” grains have a diameter of 0.5-2 mm. Sand consisting of particles of this size is called coarse sand. The other part of the sand grains has a diameter of 0.25-0.5 mm. Sand consisting of such particles is called medium-grain sand.

Finally, the smallest sand grains range from 0.25 to 0.05 in diameter. mm. It can only be measured using optical instruments. If such grains of sand predominate in sand, they are called fine-grained and fine-grained.

How are grains of sand formed?

Geologists have established that their occurrence has a long and complex history. The ancestors of sand are massive rocks: granite, gneiss, sandstone.

The workshop in which the process of transforming these rocks into sand accumulations takes place is nature itself. Day after day, year after year, rocks are subject to weathering. As a result, even such a strong rock as granite disintegrates into fragments, which become more and more crushed. Some of the weathering products dissolve and are carried away. The minerals that are most resistant to atmospheric agents remain, mainly quartz - silicon oxide, one of the most stable compounds on the Earth's surface. Sands may contain feldspars, micas and some other minerals in much smaller quantities.

The story of grains of sand does not end here. For large aggregations to form, the grains must become travelers.

I proceed from the theory of an expanding Earth, the correctness of which is indicated by the exact contiguity of the continents EVERYONE their coasts, and not just the Atlantic.
On the continents (and only on the continents) lies a granite slab. Under the granite slab is a basalt crust that evenly covers the entire planet, including the oceans.

Here it is, basalt.

And here is the structure of the cortex.

The sedimentary layer in the oceans is extremely thin - 20-30 cm, which indicates the youth of the ocean floor. Most of the sediments lying on land were formed quite a long time ago, when the planet was much smaller in size. This is a very recent past: the difference in animal species (marsupials in Australia) indicates that mammals were still in the process of rapid expansion of the planet.

The planet is still growing - in places of fractures. This is mainly in the oceans.

I'm not literate enough to insist, but it seems that the fault lines coincide with the lines of the volcanic chains. So Japan recently moved a few centimeters away from the mainland.

And now about the sand.
There are, of course, other types of sand. One British professor has been collecting and photographing such samples for many years in a row.

However, 99.9% of sand consists of pure silicon dioxide, without signs of life, in other words, quartz. And the amount of this quartz on the planet is not in favor of its terrestrial origin. So...

There are three basic primary sources of minerals:

2. Underlying basalt
3. Volcanic emissions

A certain amount of quartz is born with emissions from volcanoes, but the amount of these emissions is tiny compared to the general background.

In basalt, silica (SiO2) ranges from 45 to 52-53%.
There is even less quartz in granite - 25-35%.
And in the earth’s crust - more than 60%.

Moreover, basalt is a poor source for sand; on continents it is covered with a granite cushion, and then with sedimentary layers, that is, it is ideally protected from water, frost, cracking and rolling. Granite, when corroded, produces only half of the required quartz in its decomposition products. Whatever one may say, half of the silica on the planet is superfluous. He simply has nowhere to come from.

Here it is, this extra half of silica, which has killed more civilizations than all other factors combined.

And here she is. The alienness of this “mineral deposit” to the landscape is clearly felt. The dune will pass, and everything will immediately be restored, as it was centuries before.

Soap from the ocean? For example, here is a photo from Namibia. Once upon a time this ship ran aground - in the sea, but from the “shadow” it is clear that the wind did not blow from the sea, the wind goes parallel to the sea and, rather, slightly in its direction. And it inflated quite a lot.

Moreover, it is basically impossible to wash it out of the ocean. Think about the thin layer of sediment and the fact that there is not enough raw material in the ocean. The land with its granite is much more promising. But even here there is nowhere to get such an amount of silicon dioxide.

The conclusion is generally known to you: the sand and clay mostly fell out after several comets passed near the planet. The masses fell down along with the trade winds, the heavy ones fell immediately (hence the purity of silicon dioxide), and the light ones (red clay, in particular) were carried north, right up to Onega. I have highlighted in red the places of supposed sand deposits on the ocean floor. And, by the way, it is there: sand shoals off the coast of Canada have been known for a long time.

I think many sedimentary rocks settled not with water, but with the wind. Here, for example, is a canyon in the States. In my opinion, this is a former dune. That is, it was not the earth that was bent in all directions, but layers that were swept strictly along the already curved surface of the dune. That's why there are no cracks.

Here is the same Antelope Canyon in a different place. The water tends to wash flat; it was the wind that did this.

Here is a similar dune in Poland in 1857, by the way, a rather young dune. It is clear that it consists not of sand, but of clay.

Similar sediments of red clay cover the cultural layers of 1820 near Staraya Russa with a two-meter layer, and we see the same in the Crimea. It didn't wash up from the sea, it came on top - in red pseudo-sirocco.

I think the "Chocolate Hills" have the same windy nature.

Here they are from above.

This is what the desert looks like in Ethiopia. Personally, I see a direct analogy.

These “Scythian” mounds, photographed a long time ago somewhere in Ukraine, are probably of the same origin.

In some places what was applied caked, but is now being washed away. This is Mui Ne in Vietnam.

And this is wind erosion of red sandstone in Nubia. Has anyone ever wondered how this sandstone was formed? All these tens of meters of excess silicon dioxide for the planet...

And here is a similar erosion at the South Pole.

Moreover, it seems that it froze slowly and from above, in the presence of oxygen. Hence such visors.

We see the same thing in Mangyshlak.

There is already enough information that sedimentary layers were plastic even during the lifetime of civilized man.
To post links, you need to sort through your treasures :(

RECEIVED A VALUABLE COMMENT . I don’t know if this refutes the main version... I hope not.