Plate tectonics - the modern geological theory of the motion of the lithosphere. She argues that the crust consists of relatively coherent blocks - plates, which are in constant motion relative to each other. At the same time in the areas of expansion (mid-ocean ridges and continental rifts) as a result of spreading the new oceanic crust is formed, and the old absorbed in subduction zones. The theory explains earthquakes, volcanic activity and mountain building, most of which are confined to the boundaries of plates.
The idea of the motion of the blocks was made in the theory of continental drift, proposed by Alfred Wegener in 1920. This theory was initially rejected. The revival of the idea of movements in the solid Earth (mobilism ") occurred in 1960 when as a result of studies of geology and topography of the ocean bottom were obtained evidence of the enlargement process (spreading) of the oceanic crust and pododviganiya some parts of the crust under the other ( subduction). Combining these ideas with the old theory of continental drift has given rise to the modern theory of plate tectonics, which soon became a common concept in the geosciences.
In the theory of plate tectonics is the key element the notion of geodynamic environment - a characteristic of the geological structure with a certain ratio of plates. At the same geodynamic setting are the same type tectonic, magmatic, seismic and geochemical processes.