What sand was like many years ago. Origin of Sahara sands. Teacher of the highest qualification category

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The desert in the area of ​​the Lena River basin and its tributary the Vilyuy River has caused many people, at the very least, surprise: where do such volumes of sand come from in this place? Sand is a clear product of erosion, and it is safe to say that it is water erosion. Such a fraction (without large impurities) can be obtained only through water erosion and movement (flaking, precipitation) of masses. Here's what readers wrote in the comments to the article :

YAKUT TUKULANS l1000

In Belarusian Polesie in the Pripyat River basin there are similar sandy deposits. Moreover, they have a layer of peat layers of varying thickness.
The light areas are sands. It can be seen that these are areas where oil and gas exploration and production of these natural resources is taking place. To do this, remove the top part of the soil, the turf. The sand is exposed. But this has not been done throughout the entire territory. It can be seen that some of the sandy areas are not accessible by any road.

The following views are available:

63° 32" 16.31" N 74° 39" 25.26" E

The river is further south. High sandy shores. Purovsky district, Yamalo-Nenets Autonomous Okrug

Opened turf on the site. 63° 38" 31.17" N 74° 34" 57.89" E

Here is the next location of sand outcrops, a little to the north: Diameter is approximately 1.3 km. Link

https://www.google.com/maps/@63.88379,74.31405,2109m/data=!3m1!1e3
Link

Geologists' sites are visible. And everywhere the light color of sand.

The same picture, light-colored sand under a thin layer of tundra vegetation.

We move northeast: https://www.google.com/maps/@63.88379,74.31405,2109m/data=!3m1!1e3 Drilling site. Sand.

in place https://www.google.com/maps/@63.88379,74.31405,2109m/data=!3m1!1e3
Komsomolskoye deposit. Here the satellite filmed in higher resolution, you can see the details.

Do you think this snow is so white? I thought so too. But we move east, to the river:

It can be seen that the water is not frozen, filming in the warm season.

Sand embankment road

Gubinsky village

High sandy river bank near the town

Several photographs of areas where people damaged a thin layer of vegetation in these places:

64° 34" 6.06" N 76° 40" 45.91" E

62° 19" 50.31" N 76° 43" 17.63" E

63° 7" 35.72" N 77° 54" 31.28" E

The conclusion is that the vast expanses of the Yamalo-Nenets Autonomous Okrug are swamps, rivers and huge layers of sand under a thin layer of vegetation. Ancient sands

Let's move to the Moscow region:

Lyubertsy sand pits Lyubertsy sand deposit is located 5 km. south of Lyubertsy near the town of Dzerzhinsky near Moscow. This is one of the largest deposits of high-quality quartz sands in Russia. The thickness of the overburden rocks is from 0.3 to 22.6 m, usually 5-8 m. The useful thickness is represented by a reservoir deposit with an area of ​​​​about 30 square meters. km.

Geological information:

Quartz sands of the Moscow region were formed in coastal areas ancient seas and are found mainly in deposits of the Upper Jurassic and Lower Cretaceous. Mainly Upper Jurassic sands of the Lyubertsy and Eganovsky deposits are used. The second largest in the Moscow region is the Chulkovskoye field, located 17-18 km away. south of the city of Lyubertsy. The thickness of the sands at the field reaches 35 m.

If these layers are so ancient, millions of years old, then why is there such a thin layer of black soil and other sediments above them?

In the thickness of the Upper Jurassic quartz sands there are significant interbeds, slabs and pillow-shaped concretions of dense sandstones. Genetically, these are large sheet nodules formed due to the cementation of sand with silica (cement is predominantly quartz). Some of them are so dense and durable that they correspond rather to the designation “quartzite” than “sandstone”.

Outcrop of quartz sands of the eastern wall of the Dzerzhinsky quarry

Washing sand with a dredger in the near (Dzerzhinsky) quarry of the Lyuberetsky Mining and Processing Plant

Sandstone outcrops in the second, Forest Quarry

Petrified geoconcrete

Can be mistaken for destroyed megaliths or remains

You can see these patterns on stones. Perhaps it was carved when these rocks were still unhardened? Sharp corners and slits indicate this. If so, then it clearly happened in the recent past. And then what to do with all the geochronological data?

Wild sea buckthorn bushes grow picturesquely on the steep slopes and cliffs above the quarry. For some reason, this shrub really likes to grow in quarries. Somehow this was noticed to me in places in Krasnoyarsk.
***

So what catastrophic events or did the vast marine epochs in the geochronology of the Earth's past provoke these sand accumulations? Official science talks about ancient seas in these territories. But a thin layer of vegetation in the tundra of the Yamal Autonomous Okrug suggests the opposite. There was no accumulation of humus or inorganic soil above the sand. This indicates the very recent presence of sea water or water streams there. Maybe it was the melting glacier and large flows clean water from it flowed south. And was this glacier also quite recently? Who else thinks?

Sources:

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 is a special type of 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 acquainted with different types 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’s still not a bulk material organic origin, consisting of many small grains of sand or fractions, sedimentary rock, as well as artificial material consisting of grains rocks
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 by destruction 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 natural influence 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 varied, 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- This natural material, mined open method in quarries. 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 big amount water, as a result of which clay and dust particles are washed out of it. Sand can include various kinds 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 exposure 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 making 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, consequently, 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.
Thanks to its versatility and high quality sand of this type is widely used in various industries, including water treatment systems, glass, porcelain production, 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 as part of building materials, for washing construction sites, for sandblasting, in the construction of roads, embankments, etc. housing construction for backfilling, landscaping 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 paving slabs, 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 to the shoreline 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. Just like I do.

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 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.

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 period. 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 is 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 feldspar content 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 sharp corners The rocks are ground and crushed over time. 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; .

More 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.

MUNICIPAL BUDGETARY PRESCHOOL EDUCATIONAL INSTITUTION "KINDERGARTEN No. 61 "FLAG" OF THE CITY OF SMOLENSK

NOD OO "POZNANIE" IN THE MIDDLE GROUP

“WHERE DOES THE SAND COME FROM?”

Higher education teacher qualification category

Target: To introduce experimentally the formation of sand in nature.

Material: desert model, coast model, lump sugar, plate, tablespoon, candle, water in a jug, pipette. Cocktail straws, magnifying glasses for each child. Presentation.

Organization. Sitting and standing around the table.

PROGRESS OF THE CLASS

Guys, the weather is bad today, it’s raining outside and we won’t go for a walk. I prepared sand for you to play in a group, and it disappeared somewhere. There’s just a little bit left, you can’t build anything from it. It's a pity we won't play now. The toys are small, but there is no sand. And I really wanted to play. What to do? Don't know. Where do you think you can get sand? (Answers). In the sandbox, on the river, on the beach, in the desert...

Where does all this sand come from? (Answers) Let's turn to our computer Robitox, what will it tell us about this, where does sand come from?

Sand is particles of rocks that make up the soil. Sand turns out

when a stone disintegrates - under the influence of water, weather conditions, glaciers.

Let's check if this is true?

Experience 1. (demonstration) How sand is formed.

• Here's a piece of sugar. Can you say that it looks like a stone? It's possible, it's just as hard. Even if you squeeze it hard, it won't break. What will happen to him if drops of water fall on him? Water seeps into the cube and destroys the bonds that hold the sugar particles together, and it collapses, breaks. The same thing happens with stones, only slower.

Conclusion: Under the influence of water, stones are destroyed.

• Not only water destroys stones, but also the sun. You know that the sun is very hot. See what happens to a piece of sugar when you heat it. (Answers) That's right, it begins to melt, melt.

What happens to its shape? She begins to change. The same goes for stones.

Conclusion: Under the influence of the sun, stones are destroyed and change their shape.

• But the sun hid and it became cool. What's happening? (Answers) The sugar stone has hardened. What happened to his form? She has changed. How has the sugar stone changed in general? (Answer) Yes, the color has changed. And what else? Is it the same thickness? (Answer) No, it’s different, in some places it’s thicker, in others it’s thinner. At some point the stone becomes brittle and can break easily. The same thing happens with stones.

Robitox still wants to tell us something.

There are two places where the largest deposits can be found

sand - these are deserts with sloping seashores, where there are usually beaches.

Experience 2. Here I have a model of the desert.

• Take straws and blow on the sand. What happened? (Answers) It scattered and moved. Sand waves formed on it, and sand mounds appeared.

Not all deserts have only sand, some have only rocks.

• And if strong wind blows, what happens to grains of sand, stones? (Answers) They fly apart and hit each other. Do you think they might break if hit hard? (Answer) They can. Here we have proven to you that sand can be produced by weathering.

Conclusion: The stones are destroyed by the wind. The wind carries sand, creating sand waves and hills.

Physical education minute. Let's play a little.

The water splashes quietly,

We are floating along a warm river. (Swimming movements with hands.)

There are clouds in the sky like sheep,

They fled in all directions. ( Stretching - arms up and to the sides.)

We're climbing out of the river,

Let's take a walk to dry off. ( Walking in place.)

Now take a deep breath.

And we sit down on the sand. (Children sit down.)

If the soil consists mainly of sand, its large grains are unable to hold water and nutrients, necessary for plants. This is one of the reasons why you won't see many plants either in the desert or on the beach. Deserts are practically open to weathering.

It is not always hot in deserts; sometimes it rains, and not just rain, but heavy downpours. And on the coasts there are ebbs and flows.

Experiment 3. (demonstration) Here I have a model of the coast with sandy beach. Pieces of plasticine are rocks. The part of the model filled with sand is the beach. I will fill the remaining part with water. I will use a piece of cardboard to represent waves. What happens to the sand? (Answers) Water washes away the sand and rocks and stones remain visible. You already know what happens to stones under the influence of water. What's happening? (Answer) They collapse and turn into sand. And water currents carry sand particles all over the world.

Conclusion: The stones are destroyed by water and turn into sand.

Experiment 4. What sand looks like. Take magnifying glasses and look at it. You can pour it with your hands. Tell us what the sand looks like? What do grains of sand look like? Are grains of sand similar to each other? (Answers) Do grains of sand stick to each other? (answers) no, grains of sand do not stick to each other.

If you look closely at a handful of sand, you will see that the grains of sand have different colors. This is because sand is formed from several rocks various types. Sand can appear brown, yellow, white, and even black (if it comes from a certain volcanic rock). On some beaches, the sand may contain grains of organic origin, the source of which is the remains of living creatures, such as corals, shells, rather than rocks.

Conclusion: sand consists of small multi-colored grains that do not stick together.

So we played swami. And we not only played, but learned a lot of interesting things about sand. What did you find most interesting and what do you remember most? (Answers) Well done. Receive medals “The most inquisitive child”