What is Rock Geology?

Rock is a solid aggregate with a stable appearance composed of one or several minerals and natural glass. Rocks composed of one kind of mineral are called monoores . For example, marble is composed of calcite, quartzite is composed of quartz, etc. Rock composed of several kinds of minerals is called complex ore , such as granite is composed of quartz, feldspar, and mica The gabbro is composed of basic plagioclase and pyroxene and so on. Liquids without a certain shape, such as oil and gas, such as natural gas, and loose sand and mud, are not rocks. [1]

Rock is a naturally occurring mineral with a stable appearance or

Rocks are mainly divided according to their genesis

At the beginning of the formation of the earth, the gravity of the earth's core attracted the dust in the universe, and the condensed dust became rocks. The rocks were weathered and turned into rocks. Then it became a meteorite, before falling into the earth

Rocks appear to be broken, loose, and have secondary changes in mineral composition under the influence of solar radiation, atmosphere, water, and organisms. The effect leading to the above phenomenon is called weathering. Divided into: physical weathering. It mainly includes rock expansion and contraction caused by temperature changes, freezing of water in rock cracks and expansion caused by salt crystals, and rock expansion caused by load release. Chemical weathering. Including: the dissolving effect of water on rocks; the mineral absorbs water to form new water-containing minerals, which causes the hydration of rock expansion and disintegration; the hydrolysis of minerals and water into new minerals; the rock is affected by free oxygen in the air or water And cause damaging oxidation. biological weathering. Including the destruction of rocks by animals and plants, the mechanical damage to rocks is also a kind of physical weathering, and the erosion of their bodies by the decomposition of rocks is also a kind of chemical weathering. Man-made destruction is also an important reason for rock weathering. The degree of rock weathering can be divided into four levels: full weathering, strong weathering, weak weathering, and light weathering.

Almost 200 years ago, people might think of mountains, lakes and deserts as eternal features of the earth. But now we already know that the mountains will eventually be weathered and eroded into flat land, the lakes will eventually be filled with sediment and vegetation, and the desert will be indeterminate as the climate changes. The matter on earth is moving endlessly. Most of the rocks exposed on the surface of the earth's crust are under different physical and chemical conditions than when they were formed, and the surface is rich in oxygen, carbon dioxide and water, so the rocks are easily changed and destroyed. The whole rock appears to be fragmented, or its composition changes, eventually turning the hard rock into loose debris and soil. The mechanical fragmentation and chemical decomposition of minerals and rocks under surface conditions is called weathering. The process of removing weathering products from the place due to wind, current and glaciers is called erosion.

Surface rock is mechanically broken in place without changing its chemical composition and the role of new minerals is called physical weathering. Such as the thermal expansion and contraction of mineral rocks, ice splitting, stratification and salt crystallization can make the rock from large pieces to small pieces or even completely fragmented. Chemical weathering refers to the change of chemical composition and mineral composition of surface rocks affected by water, oxygen and carbon dioxide, and the effect of new minerals. It is mainly carried out by the equations of dissolution, hydration, hydrolysis, carbonation and oxidation.

Although all rocks will weather, not all change along the same path or at the same rate. After years of observing weathered rocks under different conditions, we know that rock characteristics, climate and terrain conditions are the main factors controlling rock weathering. Different rocks have different mineral compositions and structural structures, and the solubility of different minerals varies widely. The distribution of joints, bedding and pores and the particle size of the minerals determine the friability and surface area of the rock. The difference in weathering rate can be seen from steles of different rock types. Such as granite stele, its composition is mainly silicate minerals. Such steles are very resistant to chemical weathering. The Dali rock stele is obviously vulnerable to weathering.

Climatic factors are mainly manifested by temperature, rainfall, and reproduction conditions of living things. In a warm and humid environment, the temperature is high, the rainfall is heavy, the plants are dense, the microorganisms are active, the chemical weathering is fast and sufficient, and the decomposition of the rocks develops in depth to form a huge weathering layer. In polar and desert regions, due to the dry and cold climate, the effect of chemical weathering is not large, and the rocks are easily broken into angular debris. The most typical example is the 35-century and well-preserved Kleopatra granite spire that has stood in dry Egypt and moved to the air pollution in New York City Central Park, only 75 years later. Unrecognizable.

The height of the terrain affects the climate: the temperature and climate of the foothills and the peaks of high mountainous areas in the middle and low latitudes are very different, and their biological interface appearances are significantly different. Therefore, there is a significant difference in weathering. The degree of relief of the terrain is also of universal significance for weathering: in mountainous areas with large relief, weathering products are easily eroded by external forces, leaving the bedrock exposed and accelerating weathering. The direction of the hillside involves climate and sunshine intensity. For example, the sunny slope of the mountain body has strong sunshine and much rain. However, the backside slope of the mountain body may not have snow and ice all year round. Obviously, the weathering characteristics of rocks are quite different.

Erosion and weathering complement each other in nature, and only when rocks are weathered can they be easily eroded. When the rocks are eroded, fresh rocks can be exposed and continue to weather. The handling of weathered products is the main manifestation of erosion. When the cuttings flow with the conveying medium, such as wind or water, they will cause erosion to the ground surface, river bed and lakeshore. This results in more debris, providing material conditions for sedimentation.

Rock is gradually destroyed and decomposed into sand and soil under the action of sunlight, moisture, organisms and air, which is called weathering. Sand and soil are the products of weathered rocks.

First, weathering of rocks.

Rock loosening, spalling and cracking are all weathering phenomena of rocks.

Second, the causes of weathering of rocks.