What are soil-forming rocks

2024 Author: Henry Conors | [email protected]. Last modified: 2024-02-12 02:45

Soil is a natural body that was formed by the combined influence of animal and plant organisms, topographical features, climatic conditions and human industrial activity on the upper part of the earth's crust. In nature and human life, the soil is of great importance. Primarily, it serves as a condition for the existence of plants and animals, and secondarily, without it, a person would simply die of hunger. Thus, the soil, being a product of life, simultaneously turns out to be a condition for the existence and development of life on our planet.

Soil is the predominant means of production in agriculture. All human agricultural activity is based on the use of this resource. Crop production uses this cover as a medium for the development of plants, in animal husbandry - as the basis for the production of food for livestock. For farmers, it serves as an object of application of forces.

The entire agricultural industry is somehow tied to the use of the upper layer of the earth's crust. That is why for its expedient application it is necessary to have at least basic knowledge about the properties, composition, formation andsoil distribution.

Soil formation

The process is complex: the parent rock turns into a substance that differs significantly from the original not only in appearance, but also in its properties. The main condition for successful soil formation is the settlement of living organisms on the parent rock. For the productive reproduction of these organisms, moisture and the type of nutrition that is available to this form of life are necessary. Both of these important components appear as a result of the weathering of the rock. Soil formation is a continuous process that depends on the interaction of the original rock with the organisms that have settled on it. It proceeds as follows.

The roots of plants that have settled on the rock absorb useful substances from it, forcing them to rise closer to the surface. After the plant dies, the nutrients contained in them go into a mobile state. During this process, part of the substances is washed down by rainfall, another part settles in the upper layers of the rock, and the third is absorbed by new plants.

Decomposing, plants form humus - complex compounds of organic elements. This humus, accumulating in the upper layers of the rock, gives it new properties and stains it in a darker color. In parallel with the formation of humus, the process of its decomposition is underway.

The formation and destruction of humus, as well as the accumulation of nutrients in the upper layers of the soil, is called the biological cycle of substances - the essence of the process of soil formation. It is this cyclebarren breed becomes fertile.

Modern science divides the main soil-forming rocks by genesis into several categories. Each of them is worth considering separately.

Glacial deposits

Soil-forming rocks of this type include various moraines - the main ones, which were deposited in those places where the glacier used to be, the final ones, formed at the very edge of the glacier, and the lateral ones, located at the sides of the tongue during the valley type of glaciation.

No matter what type moraines belong to, they will be boulder-type deposits: sandy loam, sand, clay and loam - in a word, those in the total mass of which boulders are contained in various quantities. Looseness and a greater number of them are found most often in marginal moraines, clay content is characteristic of the main one.

Glacial deposits form special reliefs, especially for drumlins, terminal seas and others.

Fluvioglacial deposits

These soil-forming rocks are also called water-glacial. They got this name for the reason that they were formed due to the melt waters of glaciers. These deposits most often encircle the bottom and terminal moraines, often overlapping them. This is due to the gradual displacement of the edge of the glaciers. Fluvioglacial formations consist of small boulder or sandy-pebble deposits that form glacier deltas, esker ridges and other reliefs, eventually composing sandy-pebble fields.

Thesethe rocks are characterized by a high grade of material, a clear layering along the oblique, which is natural for sediments of flowing waters.

Soil-forming rocks of this type are adjacent to loam, which has almost smoothed layering. Experts believe that such loamy deposits are formed by small spills of near-glacial waters. Their structure is dense, viscous, has a yellowish color. This type is not characterized by the content of boulders.

Mainly covering loam is distributed in the watershed areas, lying on the moraine, from which, almost always, it has a clear demarcation.

Under the same natural conditions, loess-like loams can also be found. The chemical composition of soil-forming rocks of this type of loam is similar to the cover, but differ in carbonate content.

Mostly these deposits give soils of low fertility. The lack of humus, nutrients, low moisture content of the material lead to this result. The formation of material in hollows underlain by clays, with gradual waterlogging of the territory, leads to the formation of parent parent rocks of podzolic soils in these places. With high humidity of the site, they can be swamp-podzolic.

Lacustrine-glacial deposits

In the flat areas, soil-forming rocks are formed on the basis of sedimentary material from lakes that filled low relief areas near glaciers. In this case, horizontally layered banded clay is predominantly found, but sometimes it is possible tostumble upon sands and sandy loams with almost unexpressed horizontal layering.

Alluvial deposits

This group includes sediments that are formed in river valleys, as well as in the mouths of rivers by floods. These deposits are clearly stratified. The types of soil-forming rocks in the alluvial type of deposits will depend on natural conditions, their composition may be sandy, clayey, loamy, etc.

Lake deposits

Characterized by the absence of banded layering, inherent in lacustrine-glacial formations. In addition, they are mainly found in lake basins of various periods of formation.

Lacustrine-alluvial deposits

As the name suggests, this group includes alluvial and lacustrine deposits. These sediments are formed in the lowlands of rivers, woodlands. Especially often found in places of frequent and strong floods in the spring. Abundant moistening of rocks during a period of prolonged water stagnation leads to the appearance of lacustrine-type clay deposits. The fertile properties of soil-forming rocks of this type are low. In our country, large areas in Western Siberia, Polissya, etc. are formed by this type of deposits.

Proluvial deposits

This definition fits sediments formed by temporary descendants from the mountains. The material of these deposits is unsorted, consisting of rubble, pebble and boulder elements. You can meet these breeds atmountain foothills: even a small gorge boasts a significant volume of drifts. Merging, these materials make up the piedmont plain stripes. Very often they are significant - a striking example of this is the strip along the Kopetdag.

A distinctive feature, as one can understand, of proluvial deposits is the shape of a fan or cone. The composition of the proluvium is varied. Near the mountain ranges, these are mainly cartilaginous-rubble formations, rather rough. The farther the deposit is removed from the mountains, the finer its structure. At the greatest distance from the foot of the ridges, the proluvium consists of sands and loams.

Eluvial deposits

Soil-forming rocks of this type are formed by the weathering of rock formations that remain in place.

Based on the composition of the primary rock and the nature of weathering, one can judge what composition and type of deposits will be. Under various chemical influences of natural properties, these can be giant boulders or smooth clay products. Mountain peaks are rich in stony deposits, while lowlands with a humid climate are lined with clay deposits.

Eluvium is characterized by a gradual transition in the color of the rocks and a slight difference in the mineralogical composition of parent deposits from the resulting formations.

Deluvial deposits

The main soil-forming rocks of mountain types belong to this type of deposits. They are very closely related to the eluvial ones, being, in fact, washed away fromhills rain or melt water eluvium.

Soil-forming rocks of this type have a variety and significant layering. Most often, the layers are located parallel to the slope of the mountain. Mostly composed of clay particles. The possibility of detecting large rocky debris is very low.

Such deposits are located in places of relief reduction, near mountains or at the foot of hills.

Eluvio-deluvial deposits

The nature of eluvial and deluvial deposits is such that in large areas they are in close proximity. With such an arrangement, distinguishing where one type of sediment begins and another ends can be extremely difficult, if not impossible. The experts decided that the soil-forming rocks in this case would be called eluvial-deluvial. They are always located in mountainous regions and areas with hilly terrain.

Eolian deposits

The formation of such deposits is always associated with the accumulation of wind activity.

Of course, eolian deposits are deposits of sand that make up the area of deserts and semi-deserts. These formations create recognizable reliefs - dunes. It is by them that the origin of the rock can be unmistakably attributed to the eolian type.

In non-desert geographic areas, soil-forming rocks of this type can also be found. These include dunes of various origins: sea, river, continental. These forms are formed by sandy deposits intermingled in the past whenclimatic conditions were different, or are in the process of reweaving today - this process often occurs under the influence of human activities. In addition to morphological properties, Aeolian deposits differ greatly from all other types in their diagonal bedding and high sorting.

Loesses

These Quaternary soil-forming rocks occupy a huge place on the territory of our country. The steppes of the south and southeast consist of loess and loess-like loam almost throughout their entire length. These types of rocks have characteristic features: looseness, lack of layering, porosity. Their most important difference is in the high content of magnesium and calcium carbonates.

Sea sediments

Marine soil-forming rocks of Russia are represented mainly in the Caspian lowland. Their formation in this area occurred during the last transgression of the Caspian Sea. These deposits are found here in the form of chocolate platy dense clays, occasionally sands. Often these rocks have a strong salinity. In addition, marine deposits are characteristic of the shores of the Arctic Ocean.