In his continental drift hypothesis, Wigner tried to explain the dynamic mechanism of continental drift: the rotation of the earth will cause two components-tidal forces that drift westward and centrifugal forces that point to the equator. Due to the action of tidal forces and centrifugal forces, the pan-continent, which was originally floating like a ship, breaks up and separates from the heavier and viscous silicon-magnesium layer underneath, making large-scale horizontal drift westward and towards the equator respectively. However, these two forces caused by the earth's rotation are too weak to drive the continent to slide on the ocean shell, so everyone does not agree with his explanation.
With the continuous development of geophysics, people have more and more understanding of the structure of the earth's inner circle, and geologists have gradually begun to realize that the driving force for continental drift may come from below the earth's crust. In the 1950s and 1960s, scientists discovered more relevant evidence: ocean exploration confirmed that the seabed rock formations were thinner and younger than the land; a comprehensive study of some earthquake source zones on the seabed showed that the plates were on the seabed. Some large fault zones occurred subduction occurred; during the exploration of the Atlantic Ocean, people used sonar data to finally confirm that there is a submarine mountain range in the middle of the Atlantic Ocean-the Mid-Atlantic Ridge; The U.S."Deep-Sea Drilling Program" took deep-sea rock samples and found that the seabed magnetic anomaly strips are symmetrically distributed in parallel strips along the mid-ocean ridge.
Geologists synthesized various evidence to propose the theory of ocean spreading, and eventually developed the theory of plate tectonics. Plate tectonics holds that the earth's lithosphere is not a single piece, but is divided into many structural units called plates. The global lithosphere is divided into the Eurasian plate, the African plate, the American plate, the Pacific plate, the Indian Ocean plate and the Antarctic plate. The Pacific Plate is mainly composed of the ocean lithosphere. In addition, all other major plates are composed of the ocean lithosphere and the continental lithosphere. Beneath these plates is a denser semi-viscous layer called the asthenosphere, on which the plates can float. At the same time, there are differences in density and temperature inside the asthenosphere, which causes the material inside it to convective and drive the plate above to move.
Generally speaking, the crust within the plates is relatively stable, and the junction between plates is an area where crustal movement is relatively active. In areas where plates stretch, rifts and oceans are often formed, such as the Great Rift Valley of East Africa and the Atlantic Ocean; in areas where continental plates collide and squeeze, mountain ranges are often formed. For example, the Himalayas are formed during the collision of the Indian plate against the Eurasian plate; When the oceanic plate and the continental plate collide, trenches are often formed, becoming the deepest part of the ocean; the plates behind the trenches are squeezed and arched, creating high-rise island arcs and coastal mountains.