The shell of our planet is composed of various rocks. Under the oceans their thickness is less, under the hills there are formations up to 80 km. The composition of the stone shell of the Earth (lithosphere) in different places is different. More than 10% of the total is sedimentary rock. Most (70%) accounted for igneous formations. The rest are complex rocks resulting from exposure to high pressure and temperature.
Rocks are, in fact, clusters of minerals. It is believed that the crust consists of more than 1000 different formations. In simple rocks (gypsum, limestone) - one mineral. Basalt and granite are representatives of complex formations. This is the result of geological sedimentary processes.
Magmatic rocks, metamorphic and sedimentary, are distinguished. They differ in internal structure, have different properties, although they are often predecessors of each other.
Sedimentary rock bedded. Particles are placed in it as a result of various kinds of physical phenomena. The simplest and most common of them: destruction (breaking, crushing), transfer, deposition and sedimentation. This is how the debris rock is formed. Mineral substances or organic residues may prevail in its composition. Between them, simple or complex chemical reactions can occur with changes in existing properties or the formation of new substances. They can flow on land or in the aquatic environment.
On our planet, various processes are constantly taking place. During the formation of the Earth, its surface gradually cooled, forming the crust. Over time, it thickened. If the temperature of the planet on the surface of the planet largely depends on the atmosphere, then in its depths the substances are still stored in the molten state. Magma in the form of volcanic eruptions at times finds a way out and quickly cools.
Being exposed to weathering and other impacts, over time the rock changes its properties. It crumbles, showered, crushed. Having found constancy, the particles are deposited, accumulated, compacted. In the moving layers, they gradually sink into the depths. The conditions change, the temperature rises, the pressure rises, dehydration occurs, chemical reactions take place.
Breed from sediment is converted to metamorphic. Usually, as a result of such processes, there is a change in the internal structure of minerals. Substances acquire new properties: strength, strength, resistance to environmental influences. Geological processes continue. The breed sinks lower in the zone of high temperatures. There, it first heats up, then melts, turns into magma.
The turnover occurs in a spiral. With each turn, new compounds are formed due to the fact that complex transformations occur during transformations. Substances enter into chemical reactions, during the precipitation process new components are added, often serving as catalysts for new interactions.
Debris sedimentary rock is divided according to the size of the particles. There are four such groups. Rock particles above 1 mm are considered to be large; from 0.1 to 1 mm - sandy; 0.1–0.01 mm - silt; 0.01 - 0.001 - clayey.
Often, the division of rocks depending on the prevailing minerals and their ratio is added to the existing classification. They can act as a basis or a link between particles (for example, quartz sandstones).
Loose rocks may become denser if they are cemented. The process takes place when exposed to the basis of the binder: clay, gypsum, carbonate, iron. As a result, the rock may have a complex name, for example: siliceous or calcareous sandstone. There is also a gradation in origin: river, sea, glacial.
Structure and texture
Breed depending on the composition of minerals may have a different structure. One or another of its condition is characterized by a number of features. Allocate the structure of the rock and its texture. For the first definition, the degree of crystallinity of mineral grains, their shape and size, as well as the ratio of the constituent elements of the base and the cement substance are important.
A texture is more an external manifestation of visible signs: porosity, massiveness, schistosity or layering. Depending on the combination of these features, the material of the rock has a specific color, which can be different decorative.
The clastic sedimentary rock (monomineral) has a more uniform texture. With the "accretion" of two or more elements of different characteristics, compounds with complex chemical composition and properties are formed. Such rocks (polymineral), as a rule, have a more variegated color.
Size and shape
Debris sedimentary rock that has bored corners with a particle size of more than 100 mm is called a boulder. The process of rolling occurs with the intensive movement of the material under the action of natural forces. Debris of the same size, but angular in shape, is called lumps. Particles with a size of 10-100 mm on the same principle is divided into pebbles and rubble. Rolled gravel and angular gravel is a rock with dimensions of 1-10 mm.
Crushing and sanding most often occurred under the action of water. Such a genesis (origin) is usually divided by river, lake and sea type. Separately distinguish rocks treated by moving glaciers.
Sands (particles with a size of 0.1–1 mm) are divided into large, medium, and small ones. Less is a porous powdery polymineral rock of silt origin with fragments of 0.1–0.01 mm. The smallest particles (less than 0.01 mm) are clays. About 25% of their total amount is even less than 0.001 mm.
Chemical Sedimentary Rock
Chemogenic processes occur during precipitation of various substances from aqueous solutions. Calcium and magnesium compounds are especially important. In addition to these processes, evaporation of solutions in a closed medium is also distinguished. A characteristic feature of rocks of chemical origin is the presence of oolite grains (oval or ellipsoidal shape) and spherolites (needles). The texture and color of materials may vary and depends on the prevailing minerals.
Ferrous sedimentary chemical rock is a product of weathering of the main rocks. Manganese compounds are formed due to coagulation of colloidal solutions of hydroxides. Phosphorites and siliceous rocks were formed with the participation of microorganisms. The main components were absorbed by them from the water, processed and subsequently deposited in the oozy deposits after dying off. Salts were formed in a specific sequence. First, sulfates (anhydrite and gypsum) precipitated out, then chlorides, the latter - potassium and magnesium sulphates.
Limestone - sedimentary rock
This is a representative monomineral deposits. Limestone consists of calcite and is determined by the reaction with hydrochloric acid, which has a rapid manifestation. Two types of origin are separated: chemogenic and organogenic. If it is possible to determine what kind of organic remains a rock consists of, it is given a specific name. If it is difficult to classify, such limestone is defined as a coquina.
The foraminifera shells, protozoa, and powdered calcite deposits formed chalk. It is also a type of limestone. The material is widely used in the national economy and industry.
Chemical processes in the formation of limestone change the internal structure of the material. There are dense formations with thin crystals. Oolitic species have the form of small balls or radial rays. The minerals in them are interconnected with carbonate cement. Calcium carbonate dissolved in groundwater, precipitated after that into a sediment, turns into tuff (traverine) over time. Nates of calcite in the caves form stalactites and stalagmites.
Sedimentary rock is widely used in the construction industry. Boulders are crushed and processed into piece material. Gravel and crushed stone go on reinforced concrete products, are applied at way of a paving. Sand is not only a small filler of concrete, but also a raw material for glass, ceramics, bricks. Clay is used in the manufacture of tiles, refractory materials, and it is also a component of alumina. Some varieties are excellent adsorbents.
Magnesites go for the manufacture of binding materials. Silicon is used as an abrasive material. Lime is obtained from chalk; it is also used in the manufacture of plastics and rubber products. Margel is the best raw material for cement production.