Rock is a natural mineral aggregate with a certain structure, which is the material basis of the crust and upper mantle. According to the origin, it can be divided into magmatic rocks, sedimentary rocks and metamorphic rocks. Among them, magmatic rocks are rocks formed by high temperature condensation of molten magma on the surface or underground, also known as igneous rocks; Sedimentary rocks are the products of weathering, biological action and volcanism under surface conditions, and they are transported, deposited and consolidated by external forces such as water, air and glaciers. Metamorphic rocks are rocks formed by metamorphism due to changes in geological environment, which are formed by pre-existing magmatic rocks, sedimentary rocks or metamorphic rocks.
The deep crust and upper mantle are mainly composed of igneous rocks and metamorphic rocks. Within 0/6 km from the surface/kloc-,the volume of igneous rocks and metamorphic rocks accounts for 95%. The surface of the crust is dominated by sedimentary rocks, accounting for about 75% of the continental area, and the seabed is almost completely covered by sediments.
Kuko Buchuan replied (June 2006165438+1October 2 1):
Rock is a mineral aggregate formed by the regular combination of one or more minerals under various geological functions. For example, marble is mainly composed of calcite, while granite is composed of minerals such as quartz, feldspar and mica. According to the genesis, rocks can be divided into three categories: magmatic rocks formed by magmatic activities, sedimentary rocks formed by external forces and metamorphic rocks formed by metamorphism. Studying rocks is of great significance: a. Humans need all kinds of minerals, and some minerals are related to some rocks. B. rocks are the material basis for studying various geological structures and landforms. Rock is the basis of studying the history of the crust. A
Rock is a natural mineral aggregate with a certain structure, which is the material basis of the crust and upper mantle. According to the origin, it can be divided into magmatic rocks, sedimentary rocks and metamorphic rocks. Among them, magmatic rocks are rocks formed by high temperature condensation of molten magma on the surface or underground, also known as igneous rocks; Sedimentary rocks are the products of weathering, biological action and volcanism under surface conditions, and they are transported, deposited and consolidated by external forces such as water, air and glaciers. Metamorphic rocks are rocks formed by metamorphism due to changes in geological environment, which are formed by pre-existing magmatic rocks, sedimentary rocks or metamorphic rocks.
The deep crust and upper mantle are mainly composed of igneous rocks and metamorphic rocks. Within 0/6 km from the surface/kloc-,the volume of igneous rocks and metamorphic rocks accounts for 95%. The surface of the crust is dominated by sedimentary rocks, accounting for about 75% of the continental area, and the seabed is almost completely covered by sediments.
Petrology mainly studies the material composition, texture, structure, classification and nomenclature, formation conditions, distribution law, genesis, metallogenic relationship and evolution process of rocks. It belongs to an important basic subject in geological science.
Petrology emerged from mineralogy at the end of18th century and developed into an independent discipline. In the early development of petrology, igneous rocks were mainly studied, and metamorphic rocks began to be systematically studied in the middle of the nineteenth century, while sedimentary rocks did not attract people's attention until the early twentieth century. At present, petrology is developing along three main branches: magmatic petrology, sedimentary petrology and metamorphic petrology.
Ancient rocks all appear in the crystal basement of the mainland. The representative rocks belong to basic and ultrabasic magmatic rocks. Due to strong metamorphism, these rocks have been transformed into metamorphic rocks rich in chlorite and amphibole, which are usually called greenstone. For example, in 1973, granite gneiss with an isotopic age of about 3.8 billion years was discovered in West Greenland. From 65438 to 0979, Barton et al. determined the age of gneiss in the central Bobo forest belt of South Africa to be about 3.9 billion years.
Adache card gneiss is a metamorphic rock in northern Canada and a well-preserved part of the ancient earth surface. Radioactive dating shows that the age of Adache Ka gneiss is close to 4 billion years, which indicates that some continental materials existed hundreds of millions of years after the formation of the earth.
Recently, scientists discovered some of the oldest rocks in southwest Australia. According to the isotopic analysis results of zircon mineral crystals contained in it, it shows that its "age" is about 4.3 billion to 4.4 billion years, which is the oldest rock sample found on the earth so far. According to this discovery, it can be inferred that when these rocks were formed, there were continents and oceans on the earth. After the earth was born 200 million to 300 million years ago, it may not be covered with hot magma as people think, but it has cooled down enough to form a solid surface and oceans. The differentiation of the earth's spheres may have been completed 4.4 billion years ago.
At present, the oldest rock found in China is granite gneiss in eastern Hebei, in which the age of xenoliths is about 3.5 billion years.
Mineral composition of rocks
The types and contents of light and dark minerals in different igneous rocks are regular, and igneous rocks are divided into four categories according to color ratio:
The color ratio of light-colored rocks is 0-35; The color ratio of mesomorphic rocks is 35-65; The color ratio of dark rock is 65-90; The color ratio of dark rock is 90- 100.
Chemical composition of rocks
Magmatic rocks are mainly composed of silicate minerals, and silica is the most important component. According to its content, igneous rocks can be divided into:
Ultrabasic rock SiO 2 < 45%; 45-52% of basic rock silica
52-65% of intermediate rock silica; Acid rock silica > 65%
Rock production mode
According to its occurrence environment, it can be divided into plutonic rocks, shallow rocks and extrusive rocks. Plutonic rocks often have holomorphic structure, and extrusive rocks are mostly glassy or aphanitic.
Quantitative mineral composition
The types and contents of light and dark minerals in different igneous rocks are regular, and igneous rocks are divided into four categories according to color ratio:
The color ratio of light-colored rocks is 0-35; The color ratio of mesomorphic rocks is 35-65; The color ratio of dark rock is 65-90; The color ratio of dark rock is 90- 100.
Chemical composition of rocks Magmatic rocks are mainly composed of silicate minerals, and silica is the most important component. According to its content, igneous rocks can be divided into:
Ultrabasic rock SiO 2 < 45%; 45-52% of basic rock silica
52-65% of intermediate rock silica; Acid rock silica > 65%
Rock production mode
According to its occurrence environment, it can be divided into plutonic rocks, shallow rocks and extrusive rocks. Plutonic rocks often have holomorphic structure, and extrusive rocks are mostly glassy or aphanitic.
A small group of glutinous rice replies (June165438+1October 265438+20061October):
Rock is a natural mineral aggregate with a certain structure, which is the material basis of the crust and upper mantle. According to the origin, it can be divided into magmatic rocks, sedimentary rocks and metamorphic rocks. Among them, magmatic rocks are rocks formed by high temperature condensation of molten magma on the surface or underground, also known as igneous rocks; Sedimentary rocks are the products of weathering, biological action and volcanism under surface conditions, and they are transported, deposited and consolidated by external forces such as water, air and glaciers. Metamorphic rocks are rocks formed by metamorphism due to changes in geological environment, which are formed by pre-existing magmatic rocks, sedimentary rocks or metamorphic rocks.
The deep crust and upper mantle are mainly composed of igneous rocks and metamorphic rocks. Within 0/6 km from the surface/kloc-,the volume of igneous rocks and metamorphic rocks accounts for 95%. The surface of the crust is dominated by sedimentary rocks, accounting for about 75% of the continental area, and the seabed is almost completely covered by sediments.
Petrology mainly studies the material composition, texture, structure, classification and nomenclature, formation conditions, distribution law, genesis, metallogenic relationship and evolution process of rocks. It belongs to an important basic subject in geological science.
Petrology emerged from mineralogy at the end of18th century and developed into an independent discipline. In the early development of petrology, igneous rocks were mainly studied, and metamorphic rocks began to be systematically studied in the middle of the nineteenth century, while sedimentary rocks did not attract people's attention until the early twentieth century. At present, petrology is developing along three main branches: magmatic petrology, sedimentary petrology and metamorphic petrology.
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Basic definition
Rock is a kind of natural mineral or glass aggregate with stable appearance, which is combined in a certain way. It is the material basis of the crust and upper mantle. According to the origin, it can be divided into magmatic rocks, sedimentary rocks and metamorphic rocks. Among them, magmatic rocks are rocks formed by high temperature condensation of molten magma on the surface or underground, also known as igneous rocks or extrusive rocks; Sedimentary rocks are the products of weathering, biological action and volcanism under surface conditions, and they are transported, deposited and consolidated by external forces such as water, air and glaciers. Metamorphic rocks are rocks formed by metamorphism due to changes in geological environment, which are formed by pre-existing magmatic rocks, sedimentary rocks or metamorphic rocks.
The deep crust and upper mantle are mainly composed of igneous rocks and metamorphic rocks. Within 0/6 km from the surface/kloc-,the volume of igneous rocks and metamorphic rocks accounts for 95%. The surface of the crust is dominated by sedimentary rocks, accounting for about 75% of the continental area, and the seabed is almost completely covered by sediments.
Properties of rocks
No wonder the engineering properties of rocks are the factors of material composition (the properties of particles themselves), structure (the relationship between particles), structure (forming environment, transformation and construction) and existing environment (stress, temperature and water). If it is rock mass, it depends on both structural plane and rock mass. In most cases, the structural plane plays a controlling role.
The history of rocks
When the earth was formed, the gravity of the core sucked away the dust in the universe, and the condensed dust turned into rocks, which became rocks after weathering. Then it became a meteorite. When it does not fall into the earth's atmosphere, it is stone, iron or a mixture of stone and iron floating in outer space. If it falls into the atmosphere, it will become a meteorite that we usually see falling to the ground without being burned by the atmosphere. Simply put, the so-called meteorite is the debris left by a tiny asteroid "hitting the earth". Billions of years have passed, and there are countless rocks in the world. Nowadays, in the field of geotechnical engineering, people often divide rocks into four types according to their engineering properties: extremely hard, hard, moderately hard and weak. It is developing in the direction of quantification.
Ancient rocks all appear in the crystal basement of the mainland. The representative rocks belong to basic and ultrabasic magmatic rocks. Due to strong metamorphism, these rocks have been transformed into metamorphic rocks rich in chlorite and amphibole, which are usually called greenstone. For example, in 1973, granite gneiss with an isotopic age of about 3.8 billion years was discovered in West Greenland. From 65438 to 0979, Barton et al. determined the age of gneiss in the central Bobo forest belt of South Africa to be about 3.9 billion years.
Adache card gneiss is a metamorphic rock in northern Canada and a well-preserved part of the ancient earth surface. Radioactive dating shows that the age of Adache Ka gneiss is close to 4 billion years, which indicates that some continental materials existed hundreds of millions of years after the formation of the earth.
Recently, scientists discovered some of the oldest rocks in southwest Australia. According to the isotopic analysis results of zircon mineral crystals contained in it, it shows that its "age" is about 4.3 billion to 4.4 billion years, which is the oldest rock sample found on the earth so far. According to this discovery, it can be inferred that when these rocks were formed, there were continents and oceans on the earth. After the earth was born 200 million to 300 million years ago, it may not be covered with hot magma as people think, but it has cooled down enough to form a solid surface and oceans. The differentiation of the earth's spheres may have been completed 4.4 billion years ago.
At present, the oldest rock found in China is granite gneiss in eastern Hebei, in which the age of xenoliths is about 3.5 billion years.
The morphology and structure of microfossils in the Warrawoona Group in Western Australia are relatively complete. Whether they are cyanobacteria or bacteria is still difficult to determine. It is generally believed that early stromatolites were built by cyanobacteria, and stromatolites are indicators of the existence of cyanobacteria. If cyanobacteria appeared 3.5 billion years ago, it means that photosynthesis of releasing oxygen has begun, which leads to a question: Why did free oxygen not accumulate in the atmosphere until 2 billion years ago? From 3.5 billion years ago to 2 billion years ago, there was a gap of 654.38+0.5 billion years. Why is the accumulation of oxygen so slow? Of course, there are different explanations. For example, in recent years, it has been found that stromatolites may also be completely constructed by photosynthetic bacteria, even by non-photosynthetic bacteria.
The most important indirect evidence of the existence of the oldest life is the banded iron formation (BIF) and light carbon isotopes in western Greenland. If the evidence is established, it can be inferred that microorganisms that carry out oxygen-releasing photosynthesis have appeared on the earth 3.8 billion years ago, that is, organisms similar to cyanobacteria. According to Cloud's explanation, BIF is deposited due to the periodic release of oxygen by light and microorganisms, and the oxidation of ferrous iron into high-valent iron. Light carbon isotopes are also indirect evidence of photosynthesis. However, the objection is that the oxygen required for the formation of BIF can be provided by the photodegradation of water molecules in the atmosphere, while the light carbon isotope may come from the thermal decomposition of carbonate.
Petrology emerged from mineralogy at the end of18th century and developed into an independent discipline. In the early development of petrology, igneous rocks were mainly studied, and metamorphic rocks began to be systematically studied in the middle of the nineteenth century, while sedimentary rocks did not attract people's attention until the early twentieth century. At present, petrology is developing along three main branches: magmatic petrology, sedimentary petrology and metamorphic petrology.
Application of rocks
I. Rocks used as building materials
1. Marble: Marble is fine in texture and is often used as a wall or floor. Because marble is metamorphic from limestone, the main component is calcium carbonate, so it is also the raw material for manufacturing cement. Marble is soft and delicate, and it is a good sculpture stone. Many famous statues are made of marble, such as the famous statue of Venus. Others, such as walls or decorations, are usually made of marble, such as vases, ashtrays, tables and other household items.
2. Huagangyan: Huagangyan, a native of Jinmen, can only be seen, so almost all the old houses in Jinmen are made of Huagangyan. The huagangshi used in Taiwan Province Temple comes from Fujian, and is mostly used for dragon pillars, floor tiles and stone lions in temples.
3. Slate: Because slate is easy to crack into thin plates and easy to obtain in mountainous areas, the aborigines still use slate as building materials to build slate houses or fences.
4. Conglomerate: Some conglomerates contain pebbles and sand, with poor cementation and easy dispersion. For example, this kind of conglomerate is found in the Quaternary Touji mountain layer in western Taiwan, in which pebbles and sand are building materials.
5. Limestone: The most common limestone in Taiwan Province Province is formed by coral, commonly known as coral reef limestone. In Penghu, coral reef stones, commonly known as "stones", are used as wall building materials by residents to keep out the strong northeast monsoon and protect crops.
6. Mudstone: Because its main component is clay, it has been used as raw material for making bricks and ceramics since ancient times.
7. Andesite: Because of its hard material, it is often used as the dragon pillar, stone carving, tombstone and floor tile of the temple.
Two. A mineral from which metals can be extracted.
1. Gold deposit: After weathering and erosion with Jin Yanshi, gold will be separated into natural gold, because gold is much heavier than sediment, and it is easy to precipitate into gold after elutriation.
2. Chalcopyrite: Chalcopyrite is the most important mineral for extracting copper.
3. Galena: Galena is lead-gray with cubic cleavage and is the most important lead-containing mineral.
4. Hematite: The appearance color of hematite is iron gray or reddish brown, and it is the most important iron-containing mineral.
5. Magnetite: Magnetite is an iron-containing mineral, which is magnetic and can adsorb iron-containing substances.
Third, precious stones.
If minerals are hard, rare, durable, transparent and beautiful in color, they are often used as decorations, generally called gems. The following is a brief introduction of common gems:
1. diamond: commonly known as diamond, there are many colors, such as light yellow, brown, white, blue, green and red. , in which colorless and transparent is the highest value.
2. corundum: corundum also has many different colors, such as: red corundum is commonly known as ruby, and blue corundum is called sapphire.
3. Opal: generally colorless or white, and some have special halo.
4. Crystal: Pure single crystal is called crystal, which has different colors due to different impurities, such as topaz and amethyst. The timely fibrous microcrystalline polymer is called chalcedony; The timely granular microcrystalline polymer is called flint, and these two minerals are important jade in Taitung County.
Fourth, as a pigment.
Some minerals have special colors and can be used to make pigments, such as blue kyanite, green malachite and red cinnabar.
Other uses of verbs (abbreviation of verb)
1. Timely: Timely is the main raw material for manufacturing glass and semiconductors. For example, quartz sand in Shangfuji sandstone in Wenshuixi, Miaoli County is the main material for making glass.
2. Calcite: Calcite exists in marble and limestone and is the main raw material for manufacturing cement.
3. Muscovite: Muscovite is often used as an insulator in electric heaters because of its non-conductivity, non-thermal conductivity and high melting point.
4. Graphite: with low hardness, oily luster and black stripes, it is often used to make pencil lead. In addition, graphite can also be made into lubricants, electrodes, crucibles, etc.
5. Sulfur: Hot springs in volcanic areas contain yellow sulfur.
6. Gypsum: Gypsum is generally used to fix fracture wounds or make statues, and is also used in the construction industry.
7. Apatite: used to make phosphate fertilizer for agriculture.
8. Serpentine: a component containing magnesium, which can be used in steel-making industry.
9. Talc: low hardness and satiny; It is usually ground into powder and made into pigments, talcum powder, decontamination powder and chemicals. Grade, etc.
The origin of rocks
When the earth was formed, the gravity of the core sucked away the dust in the universe, and the condensed dust turned into rocks, which became rocks after weathering. Then it became a meteorite. When it does not fall into the earth's atmosphere, it is stone, iron or a mixture of stone and iron floating in outer space. If it falls into the atmosphere, it will become a meteorite that we usually see falling to the ground without being burned by the atmosphere. Simply put, the so-called meteorite is the debris left by a tiny asteroid "hitting the earth".
rock type
Igneous rock is also called magmatic rock. Under different geological conditions, rocks formed by the condensation and consolidation of molten materials from the interior of the earth. When molten magma overflows the surface of a volcano and solidifies, it is called extrusive rock or volcanic rock. Common volcanic rocks are basalt, andesite and rhyolite. When lava rises below the surface and condenses at a certain depth in the earth's crust, it is called intrusive rock, which can be divided into deep diagenesis and shallow diagenesis according to different intrusion sites. Granite, gabbro and diorite are typical plutonic rocks. Granite porphyry, gabbro porphyry and diorite porphyry are common shallow rocks. According to chemical composition, igneous rocks can be divided into ultrabasic rocks (SiO _ 2 content is less than 45%), basic rocks (SiO _ 2 content is 45% ~ 52%), intermediate rocks (SiO _ 2 content is 52% ~ 65%), acidic rocks (SiO _ 2 content is more than 65%) and alkaline rocks (containing special alkaline minerals, SiO _ 2)
② Sedimentary rocks. Layered rocks formed by transportation, deposition and diagenesis of weathered materials, pyroclastic materials, organic matter and a small amount of cosmic materials at normal temperature and pressure on the surface. According to the genesis, it can be divided into clastic rocks, clay rocks and chemical rocks (including biochemical rocks). Common sedimentary rocks are sandstone, tuffaceous sandstone, conglomerate, clay rock, shale, limestone, dolomite, siliceous rock, iron ore, phosphorite and so on. Sedimentary rocks occupy 7.9% of the crust volume, but they are widely distributed in the surface layer of the crust, accounting for about 75% of the land area, and the seabed is almost completely covered by sediments.
Sedimentary rocks have two prominent characteristics: one is bedding, which is called bedding structure. The interface between layers is called bedding plane, and usually the rocks below are older than the rocks above. Second, many sedimentary rocks contain "stony" remains of ancient creatures or traces of their existence and activities-fossils, which are precious materials for judging geological age and studying paleogeographic environment.
③ Metamorphic rocks. Rock formed by metamorphism of original rock. According to the types of metamorphism, metamorphic rocks can be divided into five categories: dynamic metamorphic rocks, contact metamorphic rocks, regional metamorphic rocks, migmatites and metasomatic metamorphic rocks. Common metamorphic rocks include mylonite, cataclastic rock, amphibole, slate, phyllite, schist, gneiss, marble, quartzite, amphibole, schist, eclogite and migmatite. Metamorphic rocks occupy 27.4% of the crust volume.
Rock has specific physical properties such as specific gravity, porosity, compressive strength, tensile strength, etc. It is a factor to be considered in construction, drilling, excavation and other projects, and also a carrier of various mineral resources. Different kinds of rocks contain different minerals. Taking igneous rocks as an example, basic ultrabasic rocks are related to iron-loving elements, such as chromium, nickel, platinum group elements, titanium, vanadium and iron. Acidic rocks are related to ishihara-loving elements, such as tungsten, tin, molybdenum, beryllium, lithium, niobium, tantalum and uranium. Diamond only occurs in kimberlite and K-Mg lamprophyre; Chromite is mostly produced in pure peridotite; The early Yanshanian granite in South China is rich in tungsten-tin deposits. Independent tin deposits and niobium, tantalum and beryllium deposits are often formed in granite in the late Yanshan period. Oil and coal exist only in sedimentary rocks. Iron ore in Precambrian metamorphic rocks is worldwide. Many stones are also important industrial raw materials, such as white marble in Beijing, which is a well-known building decoration material at home and abroad. Rainflower Stone in Nanjing, Shoushan Stone in Fujian and Qingtian Stone in Zhejiang are all good arts and crafts stones, and even river sand and pebbles that are not noticed by people are very useful building materials. Many rocks are also important raw materials of traditional Chinese medicine, such as medical stone (a kind of intermediate-acid dike rock), which is a very popular medicinal rock. Rock is also an important factor in tourism resources. The famous mountains, rivers and grottoes in the world are all related to rocks. Our ancestors have been using rocks since the Stone Age. In today's highly developed science and technology, people can't live without stones without clothing, food, shelter, transportation and medical care. Studying rocks, using rocks, hiding rocks, playing with rocks and loving rocks are no longer the patents of scientists, but gradually become an integral part of the lives of the broad masses.
rock weathering
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. Divided into: ① Physical weathering. It mainly includes the expansion and contraction of rock caused by temperature change, the freezing of water in rock cracks, the expansion caused by salt crystallization and the expansion of rock caused by load release. ② Chemical weathering. Includes: the rock is dissolved by water; Minerals absorb water to form new water-bearing minerals, causing hydration of rock expansion and disintegration; Hydrolysis process in which minerals react with water to decompose into new minerals; Rock oxidation destroyed by free oxygen in air or water. ③ Biological weathering. Including the destruction of rocks by animals and plants, the mechanical destruction of rocks is also physical weathering, and the erosion of rocks by corpse decomposition is also chemical weathering. Man-made destruction is also an important cause of rock weathering. The weathering degree of rocks can be divided into four grades: total weathering, strong weathering, weak weathering and mild 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. The process of removing weathered products from their original places due to the forces of wind, water and glaciers is called denudation.
In-situ mechanical crushing of surface rocks without changing its chemical composition and the function of 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.
Under the action of sunlight, moisture, living things and air, rocks are gradually destroyed and decomposed into sand, which is called weathering. Sand and soil are the products of rock weathering.
1. Weathering of rocks.
The loosening, peeling and cracking of rocks are all weathering phenomena of rocks.
Second, the causes of rock weathering.
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