What is the Earth's Crust?

The crust (qiào), a geological term, refers to a solid crust composed of rocks, the outermost layer of the earth's solid circle, and an important part of the lithosphere. According to the study of seismic waves, the interface between the crust and the mantle is Moholo Vicky discontinuities (Mojo).

Earth's crust is solid

There are 112 elements in the periodic table of chemical elements, of which 92 elements and more than 300 isotopes

evidence

Since the formation of the earth's crust, it has been moving at all times, and this movement causes the crust structure to change continuously. Earthquakes are a direct reflection of crustal movement. The more common crustal movement is long-term and slow, and it is also difficult for people to detect. It must be observed with the aid of instruments for a long time. For example, geodetic data prove that the Himalayas are still rising at a rate of 0.33 to 1.27 cm per year.

Although the earth's crust movement during the geological period cannot be known by direct measurement, it has left traces in the crust. In exposed areas of mountain rocks, sedimentary rock formations are often inclined, curved, or even staggered. This is the result of the deformation of the rock formation. In the coastal area of Rongcheng, Shandong, China, the beaches of the past are now 20 to 40 meters above the sea. In the areas of Zhangzhou and Xiamen in Fujian, the beaches of the past have risen about 20 meters above the sea, indicating that the crust in these places is rising. The ancient Haihe channel of about 7 kilometers was found on the bottom of the Bohai Sea in China, which indicates that the Bohai Sea and its coastal areas are areas with a large modern decline rate. For another example, the beautiful Yuhuashi is produced in Nanjing Yuhuatai. These smooth pebbles with beautiful patterns are natural relics of ancient riverbeds. A large number of pebbles accumulate in Yuhuatai, indicating that there used to be rivers in the past. Later, the crust rose, and the river channels were abandoned. It has become Yuhuatai gravel that is much higher than the Yangtze River.

Crustal movement classification

Crustal Movement Classification

Serial number	Classification basis	Crustal movement
1	Reference	1. Crustal movement with the ecliptic plane as the reference object; 2. Crustal movement with the earth axis as the reference object; 3. Crustal movement with geographic coordinates as the reference object; 4. Crustal movement with ground surface object as the reference object.
2	Direction of movement	1. Warp (north-north) crustal movement; 2. Latitude (east-west) crustal movement; 3. Northeast-Southwest crustal movement; 4. Northwest-Southeast crustal movement.
3	Exercise method	1. Horizontal crustal movement; 2. Vertical crustal movement;
4	Exercise results	1. Bending crustal movement; 2. Fracture crustal movement.
5	Geological age	1. Precambrian crustal movement; 2. Paleozoic crustal movement; 3. Mesozoic crustal movement; 4. Modern crustal movement; 5. Modern crustal movement.
6	Place Name + Times (within China)	1. Fuping crustal movement; 2. Luliang crustal movement; 3. Jinning crustal movement; 4. Caledonian crustal movement; 5. Hualixi crustal movement; 6. Indo-Chinese crustal movement; 7. Yanshan crustal movement; 8. Crust movement in the Himalayas.
7	Source of force	1. Internal crustal movement; 2. External crustal movement.
8	Movement scale	1. Global crustal movement; 2. Regional crustal movement; 3. Local crustal movement.
9	Cause	1. Seismic crustal movement; 2. Volcanic crustal movement; 3. Weathering and denuded crustal movement; 4. Collapsed crustal movement; 5. Sedimentary crustal movement; 6. Meteorite impact on the crustal movement;
10	depth	1. Surface crustal movement; 2. Shallow crustal movement; 3. Deep crustal movement.
11	Mechanical properties	1. Compressive crustal movement; 2. Tensile crustal movement; 3. Torsional crustal movement; 4. Crustal movement with mixed mechanical properties.

Causes of crustal movement

The causes of different types of crustal movement are different.

Crustal movement and its causes with reference to the ecliptic plane

The orbital plane around which the earth revolves around the sun is called the ecliptic plane. The position change of the crust and its constituent rocks with the ecliptic plane as a reference is the largest crustal movement.

Crustal Movement

This type of crustal movement is divided into three categories: first, the position of the crust relative to the ecliptic plane due to the rotation of the earth; second, the position of the crust relative to the ecliptic plane due to the rotation of the earth; The position of the relative ecliptic plane changes.

This type of crustal movement causes changes in day and night, season, and climate, changes in the gravitational pull of the sun and moon on the earth, and then triggers other types of crustal movement.

Causes of this type of crustal movement: caused by the origin and evolution of the solar system.

Crustal movement and its causes with the earth axis as a reference

The position change of the crust and its constituent rocks with the earth axis as the reference object is second in scale to the first type of crustal movement, which causes displacement of the earth pole and magnetic pole. The change with respect to the earth axis, that is, the earth pole has moved. This type of crustal movement causes changes in the crust and the geographical coordinates of the ground, and may also cause changes in seasons and climate, as well as changes in the gravitational balance of the earth, the sun, and the earth.

Causes of this type of crustal movement: Layered earth is formed by the rotation of the outer globe of the earth under the gravity of the sun and the moon; other causes may also exist.

Crustal movement and its causes based on geographic coordinates

The position change of the crust and its constituent material rocks with geographical coordinates as a reference. This type of crustal movement forms large-scale crustal uplifts and depressions, forming mountains, plateaus, plains, basins, and ridges and valleys.

The main sources of power for this type of crustal movement are as follows:

I. Water and wind erosion and handling and sedimentation

This type of geological action not only forms crustal movements of varying sizes, but also the sediments and sedimentary rocks that form the material basis for the formation of mountains and plateaus.

The crustal movement caused by water erosion, transportation and sedimentation reduces the relative height of the crustal, strips high and fills the depression, and makes the crustal tend to balance.

Characteristics of wind erosion and transportation and sedimentation, wind erosion of rocks and transportation and sedimentation:

Wind erosion occurs in less rainy and arid regions, not only denuding high mountains and plateaus, but also ravines and valleys.

The carrying effect of the wind varies from far to near. It is only to leave the erosion site, and the distance can reach thousands of kilometers. Its sedimentary area varies in size, up to several million square kilometers.

Wind deposition can be on land or in waters; it can be on depressions and plains, it can be on mountains and plateaus; it can form quasi-plain deposits and mountain deposits.

Aeolian terrain is easy to change and migrate. Aeolian sediments can form clastic rocks with high dip angles and can form sedimentary fold structures.

Wind deposition can occur simultaneously or alternately with water deposition.

Second, the centrifugal force from the poles to the equator generated when the earth rotates

With regard to the test of crustal material moving towards the earth's equator under the centrifugal force of the earth's rotation, geomechanics has done simulation experiments to prove it.

3. Under the gravitational force of the sun and moon, when the earth rotates from west to east, different mass blocks of the crust move from east to west. In the absence of gravitational pull from other planets, all parts of the earth's crust make uniform circular motions with the rotation of the earth. Under the gravitational force of the sun and the moon, due to the uneven composition of the various parts of the earth's crust, differential movements along the zonal direction occur, forming squeezing and separation.

The composition of the earth's crust is not uniform over a large area or a small area.

In large regions, the land has large blocks such as Eurasia, Africa, North and South America, and Antarctica, and the ocean has several blocks such as the Pacific, Indian Ocean, Atlantic and Arctic Ocean. These large blocks are different in terrain, material composition, area size, geometry, geographical location, quality, and structure. There are many small blocks in a large block. These large and small blocks on the earth's crust are affected by the gravitational pull of the sun and the moon. When the earth rotates, they move at different speeds. As the earth rotates from west to east, these large and small blocks on the crust form relative motion from east to west.

Crustal movement and its causes with ground objects as reference

The crustal movement that takes ground objects as a reference, the relative movement distance of the crustal-composing material rocks is small, which belongs to a small range of crustal movement. In addition to large-scale crustal movements that can cause this type of crustal movement, earthquakes, volcanoes, subsidence, meteorite impacts, and some biological activities can all cause this type of crustal movement.

Single and multi-factor crustal kinematics

According to the number of factors that cause crustal movement, the theory of crustal movement can be divided into two schools: one is the single-factor crustal kinematics school, and the other is the multi-factor crustal kinematics school.

The single-cause crustal kinematics school thinks that there are mainly one factor that causes crustal movement. The traditional crustal kinematics theory belongs to this school, such as the theory of continental drift, submarine expansion, plate theory, geomechanics, mosaic theory, dimple theory, fault blocks. Doctrine, multi-cycle theory, etc.

Multi-causal crustal kinematics thinks that there are many factors that cause crustal motion, which belongs to modern crustal kinematics theory. This doctrine was proposed by Jiang Fashi of China. The crustal movement is divided according to crustal movement reference objects: 1. Crustal movement with the galactic plane as the reference object; 2. Crustal movement with the ecliptic plane as the reference object; 3. Crustal movement with the earth axis as the reference object; 4. Geographical coordinates are the crustal movement of the reference object, 5. Crustal movement with the surface object as the reference object, 6. Crustal movement with the spherical surface as the reference object. Different types of crustal movement are caused by different factors, different types of crustal movement have different methods and results, and various types of crustal movement overlap each other.

Continental drift theory

A German tectonic hypothesis systematically proposed by German meteorologist Wegener (1880-1930) in 1912. He believed that there was only one huge joint ancient land in the late Paleozoic, which was called "pan-continent". In the Mesozoic, due to tidal friction and squeezing forces from the poles to the equator, the pan-continent began to split, and the lighter granite continents drifted on the heavier basalt mantle, gradually forming today's sea and land pattern. He believes that the mountains on the earth are also the products of continental drift. Cordillera and the Andes are fold mountains that are squeezed and blocked by the Pacific basaltic substrate when the American continent drifts westward. The island arc group is the debris left by the westward drift of the mainland; the arcs of the southern tip of Greenland, Florida, and Tierra del Fuego are all the result of sliding and falling off in the west; the East-West Alps and the Himalayas The large mountains are the result of the continent squeezing from the poles to the equator. According to the data at the time, Wegner demonstrated the theory of continental drift in detail in terms of geology, topography, paleontology, paleoclimate, and geodesy. This hypothesis attracted the attention of the geological and geophysical circles at that time. However, many scholars have expressed doubts about the mechanism and law of continental drift. Since the 1950s, paleomagnetic studies have shown that the movement of magnetic poles during geological history can only be reasonably explained by the theory of continental drift. Therefore, the theory of continental drift has been reborn.

Plate tectonics

In 1961 and 1962, Dietz and Hertz of the United States proposed the "seafloor expansion theory." On this basis, in 1968, French geologist Le Pisson and others pioneered the "plate tectonic theory", which has become the most popular new theory of earth sciences.

The tectonic theory of the plate divides the global lithosphere into six major plates: the Asia-Europe plate, the African plate, the American plate, the Pacific plate, the Indian Ocean plate and the Antarctic plate. In addition to the six plates, there are some small plates. Subcontinental plates can also be delineated within the continent. The plates are bounded by straits, trenches, orogenic belts. Generally speaking, the internal crust of the plate is relatively stable; the boundary between the plate and the plate is a zone where the crust is relatively active, and its activities are mainly manifested in earthquakes, volcanoes, rifts, perturbations, magma rise, and crustal subduction. Almost all volcanic and seismic activities in the world are distributed near the plate boundary.

Plate theory holds that the crust has life and death. Due to the expansion of the ocean floor, the bottom of the ocean is constantly renewed, and the continent just moves with the expansion of the ocean floor. During the relative movement of the plates, they either split to the sides or collide with each other, thus forming the basic appearance of the earth's surface. For example, 300 million years ago, the two continents of Europe, Africa, and South and North America were connected. Later, the Atlantic ridge appeared, and new oceanic crusts continued to form and expand on both sides of the central axis, which separated the above continents. For nearly 70 million years, the Indian plate has moved northward and collided with the Asia-Europe plate, resulting in the Himalayas. The Great Rift Valley of East Africa is at the beginning of the cracking of the African continent, and is in the embryonic stage of generating new oceanic crust. The Aden Bay in the Red Sea is the result of the rifting and expansion of the crust on both sides, which is in the juvenile period of the oceanic crust. The Mediterranean we know represents the end of the development of the oceans. It is the ocean left by the vast ancient Mediterranean after long-term evolution.

Regarding the driving force of the plate, some people think that it is convection in the mantle, and some people think that the "hot spots" and "hot pillars" in the mantle arch the lithosphere, causing it to slide down and push the plate under the action of gravity. There are other claims that have not been unified.

Continental driftseafloor expansionplate tectonics is a trilogy in which humans continue to deepen their understanding of crustal movement.

Earth's Extraterrestrial Rotation

The theory of the Earth's extraterrestrial rotation was proposed by Zhang Weizhi in 2012, and it was later modified. Jiang's (Jiang Fa-shi) divides crustal movements based on reference objects: 1. Crustal movement using the galactic plane as a reference object; 2. Crustal movement using the ecliptic plane as a reference object; 3. Crust using the earth axis as a reference object Movement, 4. Crustal movement with reference to geographic coordinates, 5. Crustal movement with reference to surface objects, 6. Crustal movement with spherical reference. Jiang Shifa is a representative of multi-cause crustal movement. The origin of crustal movement with the earth axis as a reference, Jiang explained that it was formed by the rotation of the outer globe of the earth. Jiang's reorganized the solid earth structure as follows:

Solid earth structure table

Earth Sphere Name				depth (Km)	earthquake P-wave velocity (Km / s)	earthquake Shear wave velocity (Km / s)	Density (g / cm3)	substance status
First level Layered	Secondary Layered		Tradition Layered
outer ball	Crust		Crust	0-33	5.6--7.0	3.4-4.2	2.6-2.9	Solid matter
	outer Over Cross Floor	Outer transition layer (on)	Upper mantle	33-980	8.110.1	4.4-5.4	3.2-3.6	section Molten substance
		Outer transition layer (under)	Lower mantle	9802900	12.813.5	6.9-7.2	5.1-5.6	Liquid-solid matter
liquid state Floor	Liquid layer		Foreign core	29004700	8.0--8.2	Cannot pass	10.011.4	Liquid substance
Inside ball	In Level		Transition layer	4700-5100	9.510.3		12.3	Liquid-solid matter
	Earth core		Earth core	51006371	10.911.2		12.5	Solid matter

Earth's Outer Ball Movement

The earth tilts and rotates and orbits in the orbit. During the summer solstice, the northern hemisphere of the earth is closer to the sun, and the solar gravitational force is greater than that of the southern hemisphere. During the winter solstice, the north and south hemispheres of the earth are subject to the opposite gravitational pull from the summer solstice. The earth's wobbling effect is caused by the rotation of the earth's moon particle, the nutation of the earth, and the precession of the earth's axis. The shaking action of the earth causes the outer ball of the earth to rotate in the direction of gravitational pull of the sun, just like the beans in a dustpan. When the dustpan is shaken, the beans will rotate toward the tilting direction of the dustpan. The inner ball movement of the earth puts a stone in a bottle filled with water, fastens a rope, holds the end of the rope to rotate the bottle, and the result is that the stone in the bottle always leans to the other side of gravity. In the same way, the Earth's inner sphere is always biased towards the other side of the sun's gravity. The rotation of the outer globe of the earth forms the movement of the earth and magnetic poles, and the movement of the earth's crust relative to the earth's axis. The rotation of Antarctica from low latitudes to the present Antarctic position is formed by the rotation of the outer globe of the earth.