The depth of weathering is limited to the depth that can be reached by the external force process. This depth is directly proportional to the weathering intensity, and it is below 10m in most areas. It is known that the maximum weathering depth occurs in tropical areas, and its lower limit is the deepest circulating depth of groundwater, which is roughly 1km.
The main feature of weathering is that rocks are destroyed or transformed in situ without being transported. Of course, this is only a relative sense of not being carried. In fact, in the weathering process, mineral dissolution, solution circulation and particle migration are also micro-treatments.
Weathering destroys the structure of rocks, changes the mineral composition of rocks, and forms residues in situ. Although weathering can't form special topography, it promotes erosion and accumulation, but it plays a wide and potential role in the formation and development of erosion and accumulation topography.
Weathering is basically divided into mechanical weathering (physical weathering) and chemical weathering. Biological weathering is a combination of physical weathering and chemical weathering. Mechanical weathering, also called disintegration, refers to the separation or dispersion of rock fragments without disintegration. Chemical weathering, also known as decomposition, mainly refers to the change of chemical composition of mineral particles that make up rocks. The deeper the study of weathering, the less clear the difference between mechanical weathering and chemical weathering. Mechanical weathering is often studied first in geomorphological Quaternary geology, because mechanical failure is generally needed before rocks interact with air, water and organisms.
Mechanical crushing is controlled by cracks between rock structure and mineral particles or cracks in mineral particles. The main processes that cause further mechanical failure and disintegration of rocks are: (1) differential expansion after pressure relief; (2) Thermal expansion and cold contraction; (3) the growth of foreign crystals in cracks and gaps; (4) Mechanical pressure generated by growing and moving organisms. Each action affects the mechanical weathering of different rock types in different ways.
Chemical weathering is a comprehensive action of dissolution and crystallization, leaching and precipitation, oxidation and reduction, hydrolysis and dehydration of minerals in rocks under certain near-surface conditions. Minerals formed under high temperature and high pressure are prone to external thermochemical reactions on the surface, resulting in compounds with large volume and low density. The most common weathering is oxidation. Oxidation is the interaction between minerals and oxygen in water and air, which generally increases their volume, especially when iron-containing minerals react with dissolved oxygen in water. Other weathering is carbonation, which is the reaction between minerals and CO dissolved in water; Hydrolysis is the decomposition and reaction of minerals and water; Hydration is the increase of water in mineral molecular structure; Alkali exchange is the exchange of electrons and ions between solution and solid minerals. Chelation is a biomineralization process in which mineral ions enter organic compounds.
The area where weathering occurs in the uppermost part of the earth's crust is called weathering zone. In the weathering zone, weathering causes rocks to disintegrate and deform, forming a new loose deposit that has not been moved, which is called residual.
Residue has two meanings. One is generalized, which refers to various types of weathering products formed by weathering; The other is in a narrow sense, which refers to the coarse and stable substances left after the fine particles and soluble substances in the weathering products are taken away by water and other power. This is actually a residue.
The crust covered with debris is called weathering crust.
Edited on 2020-0 1- 15.
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I want to find an article about the influence of weathering on geological structure
Under the action of solar radiation, atmosphere, water and living things, rocks are broken and loose, and the mineral composition changes secondary. The action leading to the above phenomenon is called weathering. External energy is energy from outside the earth, mainly including solar radiation energy, gravitational energy of the sun and the moon, and gravitational energy. The range of external dynamic geological action is limited to the depth of several meters to several kilometers on the earth's surface. Including weathering, water flow, glaciers and other external geological processes. Minerals and rocks are formed under certain physical and chemical conditions, usually under underground high temperature and high pressure. When they are exposed to the ground and change physical and chemical conditions, the stability of rocks and minerals will be destroyed. Rocks can be broken, chemically decomposed or form new minerals. Weathering: The process in which surface rocks or minerals undergo physical and chemical changes in situ due to temperature changes, atmosphere (oxygen), aqueous solution and biological action is called weathering. After it happened, the original minerals formed under high temperature and high pressure were destroyed, and some new minerals stable under normal temperature and pressure were formed, which constituted the weathering layer on the surface of continental crust. The intact rock under the weathered layer is called bedrock, and the bedrock exposed to the surface is called outcrop. Section 1 weathering type 1. Mechanical weathering The weathering process in which rocks and minerals are mechanically broken without changing their chemical composition is called mechanical weathering, which is caused by temperature changes and physical state changes of water and salt in rock gaps. The main modes of action are: 1. The temperature of rocks expands and contracts day and night, and changes with the seasons. Diurnal variation has the greatest influence, and the temperature difference between day and night and physical weathering are the strongest in inland arid desert areas. For example, in the northwest desert area, the temperature is 47℃ during the day and 3℃ below zero at night, with a difference of 50℃. (1) Different minerals have different expansion and contraction coefficients and fall off each other. (2) duplicity. During the day, the surface expands in the sun, at night, the surface contracts when it is cold, and the interior begins to expand when it is heated. 2. The change of water and salt state in rock crevices, the expansion of ice volume, the extrusion pressure on surrounding rock, the expansion of pores, and the role of ice splitting. When salt crystallizes, its volume expands. Mechanical weathering can form an inverted cone landform. 2. Chemical weathering of oxygen and water solution not only breaks the rocks near the surface, but also changes their chemical composition. This is chemical weathering. Through chemical reaction, those minerals that are unstable under the surface conditions become another new mineral (it adapts to the surface environment). Progress mode: 1. Oxidation: 1/5 pyrite FeS2(++) in the air is oxidized to limonite Fe2O3 H2O (3+), which changes from copper yellow to brownish red, darkens in color and becomes loose in structure. On the surface, it is called an iron hat, and underground is connected with a mineral deposit. 2. Any mineral is soluble in water, but the solubility varies greatly. Calcium carbonate+carbon dioxide+H2O->; Ca(HCO3)2 calcite (heavy calcium carbonate) 3. Hydrolysis: A chemical reaction in which water and minerals combine. Orthoclase +H2O- > kaolinite+hydration Some minerals absorb a certain amount of water. After gypsum +H2O- > anhydrite undergoes thorough chemical weathering, all active elements are weathered out of minerals and lost with water. Only stable elements such as iron, manganese, aluminum and nickel remain in place. If these elements are enriched to industrial value, they will become residual deposits. 3. There are two ways to destroy rocks by biological weathering: 1. Biomechanical weathering destroys rocks through plant roots, earthworm drilling, human digging and mining. 2. After the chemical weathering of organisms dies, it decomposes to form humus (colloidal substance), which is an organic acid and corrodes rocks. The loose material formed by mechanical crushing and chemical weathering of rocks on the surface of the earth's crust, after biological chemical weathering, has increased organic matter-humus. This loose substance containing humus, minerals, water and air is called soil. Factors affecting weathering The speed of weathering mainly depends on the natural geographical conditions and the mineral properties of rocks. 1. The climate conditions in cold or dry areas are scarce, and the precipitation in cold areas mainly exists in solid form, while the precipitation in dry areas is rare. Physical weathering is the main factor, followed by chemical weathering and biological weathering. Rock is broken, but there are few clay minerals formed by chemical weathering, and the soil mainly formed by biological weathering is also very thin. There is a lot of precipitation and abundant organisms in hot and humid areas, and a large amount of organic acids produced in the process of biological metabolism and corpse decomposition have strong corrosive ability, so chemical weathering and biological weathering are very strong, forming a lot of clay, which can form residues under favorable conditions. A thicker soil layer can be formed. Second, topographic conditions affect climate and indirectly affect weathering; On the other hand, on the steep slope, the groundwater level is low and there are few organisms, mainly physical weathering. Flat terrain, greatly influenced by biology, mainly chemical weathering. Three. Rock properties 1. Composition (1) magmatic rocks are more easily weathered than metamorphic rocks and sedimentary rocks. Magma is formed at high temperature and high pressure, and there are many kinds of minerals (the weathering resistance of internal minerals is very different). (2) Basic rocks in magmatic rocks are more easily weathered than acid rocks, and there are many dark minerals in basic rocks, which are easy to absorb heat and dissipate heat. (3) Soluble rocks (such as gypsum and carbonate rocks) in sedimentary rocks are more easily weathered than other sedimentary rocks. Differential weathering: under the same conditions, rocks composed of different minerals are easy to absorb heat and dissipate heat. Or rock layers composed of different lithology, the rock layers with weak weathering resistance form parallel grooves, sandstone and shale are interbedded, and shale has grooves. Through differential weathering, we can determine the occurrence of rock strata. 2. Rock structure (1) The rock structure is loose and easily weathered; (2) Unequal grains are easy to weather, while coarse grains are easy to weather; (3) The structural fracture zone is easily weathered, often forming depressions or valleys. Spherical weathering: In thick sandstone or massive magmatic rocks with developed joints, rocks are often weathered into spheres or ovals. This phenomenon is called spherical weathering, which is the result of the joint action of physical weathering and chemical weathering. The main conditions of spherical weathering are: (1) the rock has thick layer or massive structure; (2) Developing multiple groups of cross cracks; (3) Rock is difficult to dissolve; (4) The rocks are mainly of equigranular structure. Rock blocks cut by more than three groups of faults have obvious external edges and corners. In the process of weathering, the edges and corners are weathered first and then spherical. The weathering crust and its research significance 1. After weathering, some fusible substances in rocks are taken away by water, and the remaining clastic rocks and some new minerals formed by chemical weathering remain in place. These weathering products left in place are called residues. The mineral composition, chemical composition and color of the residue are related to the underlying stratum (original rock). They are often angular, not sorted, not layered, and gradually transition downward. In areas with biological activities, soil grows on the ruins. Weathering crust: Debris and soil form discontinuous thin shells on the surface of continental crust, which is called weathering crust. 2. Weathered crust can be composed of a layer of debris or several layers of debris with different weathering decomposition degrees, with gradual transition between layers and no obvious dividing line. Because weathering is strongest on the surface and weakened in the deep, it has vertical zoning. A complete weathering crust can be divided into the following layers from bottom to top: 1 layer: unweathered bedrock; Layer 2: semi-weathered layer, where rocks are broken into pieces by machinery; The third layer: residual soil, physical and chemical weathering, from bottom to top, weathering degree from shallow to deep, debris particles from large to small; The fourth layer: soil layer, which has experienced long-term physical weathering, chemical weathering and biological weathering. In areas without biological weathering, the soil layer is missing. 3. The thickness and composition of weathering crust vary from place to place. Generally, in the hot and humid climate area, the weathering crust is thick, and residual deposits such as iron, manganese, aluminum and nickel may be formed (weathering crust deposit). In arid areas, the weathering crust is very thin, often only a few tens of centimeters, and its structure is simple. Paleoweathering crust: If the weathering crust is covered by late sediments, it is called paleoweathering crust. 4. The research significance of the crust movement and paleogeography of the weathering crust (1): The weathering crust can be fully developed after long-term stability or uplift, and the paleoweathering crust represents the paleosedimentary discontinuity and develops tectonic movement. (2) Paleogeography: land, different climatic conditions and different wind crust characteristics. (3) Minerals: residual deposits and residual sand deposits (gold and diamond). The thickness of weathering crust in a reservoir project is underestimated, and the leakage under the dam is serious after water storage. Re-discussion on the phenomenon that weathered rocks are broken and loose under the action of solar radiation, atmosphere, water and biology, and the mineral composition changes secondarily. The action leading to the above phenomenon is called weathering. About 200 years ago, people may think that mountains, lakes and deserts are the eternal characteristics of the earth. But now we know that mountains will eventually be weathered and denuded to the ground, lakes will eventually be filled with sediments and vegetation, and deserts will be uncertain with climate change. Matter on the earth moves endlessly. Most rocks exposed to the earth's crust are in different physical and chemical conditions from those when they were formed, and the surface is rich in oxygen, carbon dioxide and water, so rocks are easy to change and destroy. It shows that the whole rock has become fragments, or the composition has changed, and finally the hard rock has become loose debris and soil. The process of mechanical crushing and chemical decomposition of minerals and rocks under surface conditions is called weathering. Due to the dynamic effects of wind, water flow and glaciers, the process of removing the weathered products from their original places is called denudation, and the process of mechanically crushing the surface rocks in situ without changing their chemical composition or new minerals is called physical weathering. Such as thermal expansion and cold contraction of mineral rocks, ice splitting, peeling and salt crystallization. , can make the rock from large to small or even completely broken. Chemical weathering means that the chemical composition and mineral composition of surface rocks change under the action of water, oxygen and carbon dioxide, and new minerals are produced. Mainly through the equations of dissolution, hydration, hydrolysis, carbonation and oxidation. Although all rocks will be weathered, they don't all change along the same road or at the same speed. After years of observation of weathered rocks under different conditions, we know that rock characteristics, climate and topographic conditions are the main factors controlling rock weathering. Different rocks have different mineral compositions and structures, and the solubility of different minerals is also very different. The distribution of joints, bedding and pores and the grain size of minerals determine the brittleness and surface area of rocks. The difference of weathering speed can be seen from the stone tablets of different rock types. For example, granite stone tablets are mainly composed of silicate minerals. This kind of stone tablet can resist chemical weathering well. Marble stone tablets are obviously prone to weathering. Climate factors mainly include temperature, rainfall and biological reproduction. In a warm and humid environment, the temperature is high, the rainfall is heavy, the plants are dense, the microorganisms are active, and the chemical weathering is fast and sufficient. The deep decomposition of rocks can form a thick weathered layer. In polar and desert regions, due to the dry and cold climate and little chemical weathering, rocks are easily broken into angular debris. The most typical example is that the well-preserved Kleopatra granite spire, which has stood in dry Egypt for 35 centuries, was moved to the central park in new york City, where the air pollution is serious. It was 75 years before it was completely unrecognizable. The height of the terrain affects the climate: the temperature and climate of the foothills and tops of high mountains in the middle and low latitudes are very different, and the biological characteristics are significantly different. Therefore, there are significant differences in weathering. The degree of undulation is also of universal significance to weathering: in mountainous areas with large undulations, weathering products are easily eroded by external forces, exposing bedrock and accelerating weathering. The trend of hillside is related to climate and sunshine intensity. For example, the sunny slope of the mountain has strong sunshine and much rain, while the sunny slope of the mountain may not be frozen all year round. Obviously, the weathering characteristics of rocks are quite different. Erosion and weathering complement each other in nature. Only when rocks are weathered can they be easily eroded. When the rock is denuded, fresh rock will be exposed to continue weathering. The transportation of weathering products is the main embodiment of erosion. When cuttings flow with conveying media (such as wind or water), they will erode the surface, river bed and lakeshore zone. In this way, more debris is produced, which provides material conditions for deposition. ......
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Briefly describe the types of weathering and its influence on rocks.
The speed of weathering mainly depends on the natural geographical conditions and the mineral properties of rocks. 1. The climate conditions in cold or dry areas are scarce, and the precipitation in cold areas mainly exists in solid form, while the precipitation in dry areas is rare. Physical weathering is the main factor, followed by chemical weathering and biological weathering. Rock is broken, but there are few clay minerals formed by chemical weathering, and the soil mainly formed by biological weathering is also very thin. There is a lot of precipitation and abundant organisms in hot and humid areas, and a large amount of organic acids produced in the process of biological metabolism and corpse decomposition have strong corrosive ability, so chemical weathering and biological weathering are very strong, forming a lot of clay, which can form residual sediments under favorable conditions. A thicker soil layer can be formed. Second, topographic conditions affect climate and indirectly affect weathering; On the other hand, on the steep slope, the groundwater level is low and there are few organisms, mainly physical weathering. Flat terrain, greatly influenced by biology, mainly chemical weathering. Three. Rock properties 1. Composition (1) magmatic rocks are more easily weathered than metamorphic rocks and sedimentary rocks. Magma is formed at high temperature and high pressure, and there are many kinds of minerals (the weathering resistance of internal minerals is very different). (2) Basic rocks in magmatic rocks are more easily weathered than acid rocks, and there are many dark minerals in basic rocks, which are easy to absorb heat and dissipate heat. (3) Soluble rocks (such as gypsum and carbonate rocks) in sedimentary rocks are more easily weathered than other sedimentary rocks. Differential weathering: under the same conditions, rocks composed of different minerals are easy to absorb heat and dissipate heat. Or rock layers composed of different lithology, the rock layers with weak weathering resistance form parallel grooves, sandstone and shale are interbedded, and shale has grooves. Through differential weathering, we can determine the occurrence of rock strata. 2. Rock structure (1) The rock structure is loose and easily weathered; (2) Unequal grains are easy to weather, while coarse grains are easy to weather; (3) The structural fracture zone is easily weathered, often forming depressions or valleys. Spherical weathering: In thick sandstone or massive magmatic rocks with developed joints, rocks are often weathered into spheres or ovals. This phenomenon is called spherical weathering, which is the result of the joint action of physical weathering and chemical weathering. The main conditions of spherical weathering are: (1) the rock has thick layer or massive structure; (2) Developing multiple groups of cross cracks; (3) Rock is difficult to dissolve; (4) The rocks are mainly of equigranular structure. Rock blocks cut by more than three groups of faults have obvious external edges and corners. In the process of weathering, the edges and corners are weathered first and then spherical. The factors affecting the hardness of rock can also be divided into two categories: natural factors and technological factors: (1) The more isochronous minerals or debris in rock, the greater the hardness of cement, the finer the particles of rock, the denser the structure and the greater the hardness of rock. However, with high porosity and low density, the hardness of rocks with developed fractures will decrease. (2) Rock hardness has obvious anisotropy. But the influence of bedding on rock hardness is just the opposite to that on rock strength. The hardness perpendicular to the bedding direction is the smallest, and the hardness parallel to the bedding direction is the largest, and the difference between them can reach 1.05 ~ 1.8 times. The anisotropy of rock hardness can well explain the causes and laws of borehole bending, and directional drilling can be carried out by using this phenomenon. (3) Under the condition of uniform compression in all directions, the hardness of rock increases. The lower the rock hardness under normal pressure, the faster the hardness increases with the increase of confining pressure. (4) Generally speaking, with the increase of loading speed, the plastic coefficient of rock will decrease and the hardness will increase. However, when the impact velocity is less than 10m/s, the hardness changes little. The effect of loading speed on the hardness of low strength, high plasticity and porous rock is more significant. In the process of measuring rock hardness, we should pay attention to distinguish the hardness of rock-forming mineral particles from the bonding hardness of rocks. The former mainly affects the life of drilling tools, while the latter has a great influence on ROP in drilling. Thirdly, the main factors affecting weathering are climate, vegetation, topography and rock characteristics. (1) Climate and vegetation Climate factors, including temperature, rainfall and humidity, are important factors to control weathering. On the one hand, temperature controls the progress of chemical weathering by controlling the speed of chemical reaction, on the other hand, it directly affects physical weathering, such as temperature difference weathering and ice crack. Rainfall and humidity affect physical, chemical and biological weathering through temperature change of medium, composition change of aqueous solution and growth of vegetation. In different climatic zones on the surface, the climatic conditions vary greatly. In polar and alpine regions, the temperature is low, vegetation is scarce, and surface water mainly exists in solid form, so physical weathering is dominant in this region, especially ice cleaving is widespread, and chemical weathering and biological weathering are weak. In arid desert areas, vegetation is scarce, the daily temperature range is large, rainfall is small, and the air is dry, so chemical weathering and biological weathering are weak, while physical weathering, such as temperature difference weathering, salt crystallization and deliquescence, are the main weathering forms in these areas. In the low latitude hot and humid climate zone, there are abundant rainfall, lush vegetation, high temperature, moist air and rapid chemical reaction, so chemical weathering and biological weathering are obvious, and the weathering depth often reaches several meters. If the climate in these areas remains stable for a long time, the decomposition of rocks can develop in the depth direction and form extremely thick weathering products. This climatic condition is also the most favorable condition for the formation of weathered mineral-bauxite. The influence of vegetation on weathering is manifested in two aspects: on the one hand, it directly affects the weathering of organisms, and the weathering of lush organisms is strong, while the weathering of organisms in places with sparse vegetation is weak; On the other hand, it indirectly affects the process of physical weathering and chemical weathering. The surface of rock is covered with plants, which reduces the direct contact between rock and air, reduces the temperature difference change of rock surface and weakens physical weathering. The lush vegetation brings more organic acids and humus, which makes the aqueous solution in the surrounding environment more corrosive, thus accelerating the process of chemical weathering. In fact, the influence of vegetation on weathering is inseparable from climatic conditions, with hot and humid climate and lush vegetation; However, drought, cold and sparse vegetation. Climate and vegetation have the most significant effects on soil. Different climates have their typical soil types. When climatic conditions change, soil types will also change, so some people call soil "a function of climate". For example, in the cold and humid tundra climate zone, ice marsh soil is often formed, in tropical and temperate desert areas, brown soil and cinnamon soil are formed, and deciduous trees in temperate regions are widely distributed in Ye Sen. (2) The terrain conditions include three aspects: one is the height of the terrain, the other is the ups and downs of the terrain, and the third is the trend of the hillside. The height of the terrain affects the local change of climate. The vertical zoning of climate in the middle and low latitudes is obvious, the climate at the foot of the mountain is hot, the climate at the top of the mountain is cold, and the vegetation characteristics are different, which affects the weathering type and speed. This phenomenon is obvious in most areas of China and Yunnan. The steep terrain affects the groundwater level, vegetation development and preservation of weathering products, thus affecting the weathering process. In steep terrain, the groundwater level is low, the vegetation is few, and the weathering products are not easy to preserve, which makes the bedrock exposed continuously, thus accelerating weathering. The weathering types and intensities of sunny and shady slopes are also different. The sunny slope has long sunshine time, high humidity and many vegetation, so it has strong weathering. For example, the southern slope of the Himalayas faces the Indian Ocean, with hot and humid climate and strong chemical and biological weathering, while the northern slope is dry and cold, mainly developing physical weathering. (3) Rock characteristics The influence of rock characteristics on weathering includes rock composition, structure, structure and cracks. Minerals with different rock compositions have different weathering resistance, so rocks composed of different minerals have different weathering resistance. For example, magmatic rocks composed of olivine, pyroxene and feldspar are easy to weather, while sedimentary rocks composed of quartz sand have strong weathering resistance. Therefore, the weathering of rocks composed of minerals with weak weathering resistance forms potholes, while the components with strong weathering resistance are relatively prominent, and the uneven phenomenon appears on the rock surface, which is called differential weathering. Rock structure, mineral granularity, distribution characteristics, cementation degree and bedding have obvious effects on the speed and strength of weathering. Other conditions being the same, the well-cemented rock composed of fine-grained and equal-grained minerals has strong weathering resistance and slow weathering speed. The development of cracks in broken rocks increases the contact area between rocks and water solution and air, and enhances the fluidity of water solution, thus promoting weathering. If the minerals of some rocks are evenly distributed, such as sandstone, granite, basalt, etc. There are three groups of nearly vertical cracks, and the rock is cut into many cubic blocks with different sizes. The free surface area at the corners of the blocks is large, which is easily damaged by factors such as temperature, aqueous solution and gas. After a period of weathering, the edges and corners of the stone disappeared, and large and small spheres or ellipsoids were formed on the rock surface. It is of great significance to study weathering. In the weathering process, some insoluble elements or substances can accumulate in situ and nearby, enriching useful minerals, such as iron ore, bauxite and nickel ore. According to current statistics, bauxite related to weathering accounts for 85% of the world's total reserves; Weathering can also form some prospecting targets such as "iron hat" It is very important to study the ancient weathering crust for understanding the history of crustal development in a region, because the ancient weathering crust represents a long-term land environment and reflects a rising movement of the crust. Soil is a function of climate. Studying paleosols (mainly Paleogene and Quaternary paleosols, the older paleosols are difficult to identify) is helpful to restore paleoclimate and paleogeographic environment. Because the strength of weathered rocks is weakened and the water permeability is increased, which is extremely unfavorable to engineering buildings, it is necessary to know the distribution and thickness of weathered shells and the strength of weathered rocks when building large-scale projects, so as to take corresponding measures to ensure the engineering quality. In addition, the study of weathering crust and weathering is also of practical significance to agricultural and forestry planting and land use.
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Terrain formed by weathering
Why is weathering the forerunner of all external geological and geomorphological processes?
1. Weathering refers to the whole process that hard rocks and minerals on the surface or near the surface contact with the atmosphere, water and living things, undergo physical and chemical changes and form loose deposits in situ. 2. Weathering refers to the process of mechanical disintegration and chemical changes of rocks on the surface or near the surface due to temperature changes, the action of water and aqueous solution, and the action of atmosphere and biology. In addition, the growth of plant root elements, the activities of cave animals and the decomposition of rocks by humic acid formed after plant death can all change the state and composition of rocks. Rock weathering is closely related to moisture and temperature. The higher the temperature, the greater the humidity and the stronger the weathering. However, in dry environment, physical weathering is dominant, and with the increase of temperature, physical weathering is gradually strengthened. In humid environment, chemical weathering is the main function, which is gradually strengthened with the increase of temperature. Physical weathering is mainly affected by temperature changes, while chemical weathering is greatly affected by temperature and humidity changes. Judging from the thickness of the surface weathering crust, the temperature is high and there is much water.