Weathering

There are several types of weathering, which can prevail to varying degrees:

1. physical or mechanical (friction, ice, water and wind);
2. chemical;
3. biological (organic);
4. radiation (ionizing).

Physical or mechanical

The larger the temperature difference during the day, the faster the weathering process. The cause of mechanical weathering is also the ingress of water into cracks, which when frozen increases in volume by 1/10, which contributes to even greater weathering of the rock. If blocks of rock fall, for example, into the river, then there they slowly grind and grind under the influence of the current. Mudflows, wind, gravity, earthquakes, volcanic eruptions also contribute to the physical weathering of rocks.

Mechanical grinding of rocks leads to the transmission and retention of water and air by the rock, as well as a significant increase in surface area, which creates favorable conditions for chemical weathering. As a result of cataclysms, rocks can crumble from the surface, forming plutonic rocks . The lateral rocks exert all the pressure on them, which is why plutonic rocks begin to expand, which leads to the scattering of the upper layer of rocks.

Chemical

Chemical weathering is a combination of various chemical processes that result in further destruction of rocks and a qualitative change in their chemical composition with the formation of new minerals and compounds. The most important factors for chemical weathering are water , carbon dioxide and oxygen . Water is an energetic solvent for rocks and minerals. The main chemical reaction of water with igneous rock minerals - hydrolysis - leads to the replacement of cations of alkaline and alkaline-earth elements of the crystal lattice with hydrogen ions of dissociated water molecules:

The resulting base (KOH) creates an alkaline medium in the solution, in which further destruction of the orthoclase crystal lattice occurs. In the presence of carbon dioxide, KOH goes into the form of carbonate:

The interaction of water with rock minerals also leads to hydration - the addition of water particles to mineral particles. For example:

In the chemical weathering zone, the oxidation reaction is also widespread, which many minerals containing oxidizable metals undergo. A striking example of oxidative reactions in chemical weathering is the interaction of molecular oxygen with sulfides in an aqueous medium. So, during the oxidation of pyrite, along with sulfates and hydrates of iron oxides, sulfuric acid is formed , which is involved in the creation of new minerals.

Biogenic

Biogenic weathering is produced by living organisms ( bacteria , fungi, viruses , digging animals, lower and higher plants , lichens). In the process of their life, they act on the rocks mechanically (destruction and crushing of rocks by the growing roots of plants, when walking, digging holes with animals). A particularly large role in biogenic weathering belongs to microorganisms .

Radiation

Radiation weathering refers to the destruction of rocks under the influence of radiation , or solar radiation. Radiation weathering affects the processes of chemical, biological and physical weathering. A typical example of a rock susceptible to radiation weathering is regolith on the moon .

As a result of the action of weathering agents, weathering crusts are formed. There are crusts of physical and chemical weathering.

The product of weathering in a number of regions of the Earth on the surface of the day are the Kurums . Under certain conditions, weathering products include crushed stone , wood , slate fragments, sand and clay fractions, including kaolin , loess , individual rock fragments of various shapes and sizes depending on the petrographic composition, time and weathering conditions.

• Erosion (geology)
• Desquamation
• Kigilyahs
• Kurums
• Geomorphology

• Weathering in geography.
• Soviet film for students “Weathering”