1. The theory of plate tectonics is the theory that suggests that there are tectonic plates and they are moving on surface of our planet.
According to this theory, the forces from the mantle layer create a very big pressure on the crust, and they managed to crack it in numerous pieces. It doesn't stop there though, as those same forces actually are moving the tectonic plates in certain direction. This results in different types of interaction between the plates, as they can move away from each other, slide past each other, or collide with each other.
This is what gives the basis of the formation of the majority of the physical features on the surface on our planet, but it can also influence on destroying physical features.
2. There are several evidence that point to the plate tectonics theory and that it is in fact a real process that is happening on our planet constantly.
The puzzle like matching of certain parts of the continents, especially the eastern coast of South America and the Western coast of Africa, is one evidence, as they look like they have been together but then broken apart.
The mid-ocean ridges provide evidence about the formation of new crust. They also show how the crust is pushed sideways, in the manner that the youngest crust is at the mid-ocean ridge itself, while the bigger the distance from it, the older the crust is.
The fossil records are another evidence. There are lot of fossils of the same species that have been found in continents that are not connected in the present. This is simply not possible, as even if the same species is put in another location, it will gradually evolve new characteristics because of the environment. This has been the case with fossils of the same species being found on Antarctica, South America, and Africa, pointing that once these three continents were part of one larger land mass.
3. There are seven major tectonic plates on Earth, but also several smaller ones. Most of the major plates are continental: African, Eurasian, North American, South American, Indo-Australian, and Antarctic plates. Only one of the major plates is actually oceanic, and that is the Pacific plate.
Not to be mistaken though, big portions of the continental tectonic plates are actually under water, as they are not all above it and creating enormous land mass, just that the crust doesn't have the oceanic plate composition.
The Eurasian plate is the largest of the continental plates, stretching from the eastern side of Iceland to the eastern part of Siberia.
The North American plate is stretching from the western side of Iceland to the eastern part of Siberia.
The African plate is actually in a process of divergence, as it splits into two separate plates gradually, the Somali and Nubian plates.
The Indo-Australian plate has been formed by the merging of the Indian and Australian plates, though India is part of Asia and it seems the other way.
The South American plate is gradually moving toward west an it will most probably isolate itself from North America, while the Antarctic plate is moving toward the lower latitudes, so in millions of years in the future it will probably not be frozen anymore. T
he Pacific plate is by far the largest of any other oceanic plate, but it is decreasing in size from all sides, as it subducts below continental plates on all sides.
4. The tectonic plates need to experience enormous amount of force upon them in order to be able to move. This enormous amount of force comes from below them, from the mantle layer. These forces are known as convection currents.
The convection currents are circular movements of material in the mantle layer, between its upper and lower parts. This happens because of the difference in density and temperature between the material in its upper and lower part.
The material that is in the upper part is cooler and it has bigger density, while the material in the lower part has higher temperature and lower density. The material from the upper part sinks gradually toward the bottom as it is heavier, while the material from the bottom moves upward as it is lighter. Once the material from the top that came to the bottom becomes hotter and less dense, it moves in the opposite direction, thus upward, and the process constantly continues. The movement upwards creates enormous pressure on the crust, resulting in cracking it, as well as moving slowly on the surface of our planet.
