Meaning of plate tectonics
The word ‘plate’ was first used by Canadian geophysicist J.T. Wilson in 1965. A terrestrial solid land is called a plate. The study related to the nature and flow of these plates is called plate tectonics. The emergence of the plate concept is based on two facts –
(1) The concept of continental flow and
(2) The concept of ocean floor expansion.
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Morgan has accepted 6 major and 14 minor plates in the world. It is known that they can move independently from the small plate. The edges of these plates are most important because earthquakes, volcanoes, and tectonic events occur only along these edges. Therefore, the study of these edges of the plate is important. In general, the edges of the plate are divided into three types-
(1) Destructive plate edge – The material moves down along these edges and the plate edges wear out.
(2) Protective plate edge – Two plates move side by side with the help of protective edges, due to which the fraction is created and there is no difference in the surface area of the edges of the plate.
(3) Constructive plate edge – New materials are formed with the help of constructive edges. This process takes place along the Mediterranean Ridge.
Harry Hess’s Plate Tectonics Theory Hess propounded the ‘plate tectonic theory’ in 1960 in favor of the flow of continents. According to Hess, continents, and oceans rest on different plates. When these plates move, the continents and ocean floor are also displaced with them. From the Carboniferous era, the current continents and oceans have been formed due to the transfer and flow of various plates of Pangea. Their formats may also change in the future as the flow of these plates is still going on.
The edges of the plate can be divided into three classes
(1) Where two plates are moving in opposite directions to each other, that center is called the creep center. New material is created between two plates. Hence its edges are called constructive edges.
(2) Where two plates collide, their edges are called destructive edges because the edge of a plate, which is made of heavy material, goes down, where it destroys and merges in depth. Is.
(3) Where two plates slide side-by-side and there is no mutual interaction between them, a fault is formed, such edges are called protective edges. Therefore, the process of mountain formation also becomes complicated. It is to be remembered that plates are both oceanic and terrestrial,
(i) Eurasian Plate
The Eurasian Plate is the largest of the four major plates that make up Earth’s lithosphere. It extends from the North Pole to the South Pole, and from the Arctic Ocean to the Pacific Ocean. The Eurasian Plate is subdivided into five tectonic plates: North European, Siberian, Far East, Middle European, and Indian.
(ii) Indian plate
The Indian Plate is a tectonic plate located in Asia that lies between the Arabian Sea and the Bay of Bengal. It extends southward to embrace parts of Sri Lanka and part of Bangladesh before it turns westward again to join with other plates in forming an island arc system.
(iii) American Plate
The American Plate, also known as North America or Laurentia, is an oceanic tectonic plate that includes most of North America and Greenland along with much of Central America. It extends eastward beyond Iceland and Greenland into Europe, China, and Russia on its way to subduction beneath Africa.
(iv) African Plate
The African Plate includes all landmasses in Africa south of about 55°N latitude (excluding Madagascar). It includes parts of Asia Minor, Iran, and Australia as well as Madagascar
(v) Antarctic Plate and
(vi) Pacific Ocean Plate.
Plate Tectonics and the Origin of Fold Mountains
The origin of fold mountains can also be explained based on plate tectonics theory.
(a) The edge of the oceanic plate subducted under the continental edge at the destructive edges of the Pacific Ocean Plate and the American Plate. As a result, as a result of compressive movement under the oceanic crust, the material along the western edge of North and South America was folded and the Rocky and Andes ranges were formed. In the above situation, mountains were formed due to the collision of the continent and oceanic plate.
(b) Even when there are continental parts on both plates, their collision led to the formation of mountains. About 65-70 million years ago, the Tethys Sea floundered in place of the Himalayas. To its north were the Asian plates and to the south were the Indian plates.
(c) When two plates have an oceanic bottom crust, due to their collision, the crust of one plate gets pushed into the ocean crater under the other plate, due to which the islands arc and island arch mountains are formed by the compression produced. The best example of such a situation comes from the island arc of Japan.
According to Thelantine and the Moors, 600 million years ago, all the land parts were in the form of the first register. 500-600 million years ago (in the Cambrian era) the first Pangea broke up. 1500 million years ago Pangea split again and the Atlantic re-opened, due to the movement of ‘Tertiary Age’ plates, the present fold mountains were formed. It should be remembered that before the Cambrian era, the continental part would have been less than in the present time.
Initially, due to the formation of island arcs away from the coast of the continents and their collision with the continental coastal parts, the size of the continents would have increased. On this basis, predictions can also be made about the upcoming formation of the continents. For the last 200 years, the Atlantic Ocean has been expanding continuously, while the Pacific Ocean is contracting due to the movement of the American Plate.