Is it possible to say with certainty how the Earth appeared, what metamorphoses it underwent, and through what stages of development it passed? The planet is more than four and a half billion years old, therefore no one has reliable information. Science can only offer theories that are supported by certain facts, findings, or logical conclusions. Evidence of the processes taking place in the universe allows us to make assumptions.
It all started with the rotation of an interstellar cloud or nebula, which during its movement changed density due to the action of gravitational forces on each individual element. As a result, our solar system emerged from the gas-dust cloud. This process took place about five billion years ago.
Our planet Earth became inhabited about three and a half billion years ago, and many changes have taken place since then. The most notable of these were geographical. For example, lithospheric plates used to be located in such a way that many inhabitants of the Earth could freely migrate from North America to Australia.
But back to how the Earth appeared. Heavy metal-containing rocks sank deeper into the planet, and for hundreds and hundreds of millions of years formed the core. Lighter rocky elements formed crust on the surface. Compression under the influence of gravity and the release of energy due to the radioactive decay of some chemical compounds led to even more intense heating of the inner regions of the Earth. The temperature grew, so tricks of tension began to appear at the junction with the crust. This happened in those places where the convective rings of the red-hot material of the mantle converge into a flow directed upwards.
The mantle currents forced lithospheric plates to constantly be in motion and shift relative to each other. They are moving now, annually moving a centimeter apart. This is invisible to the eye, but a centimeter multiplied by billions of years gives a tangible distance. According to the theory of continental drift, which was first put forward by A. Veneger, Africa and South America were once a single continent. The theory found its confirmation in much later studies of the ocean floor. It also turned out that before the Earth appeared in the form in which we know it, the South Magnetic Pole changed places with the North as much as 16 times.
It is impossible not to mention the stages of development of life on the planet, because it was uninhabited for a very long time after it appeared. The earth originally had an atmosphere consisting of carbon dioxide, ammonia, methane and hydrogen sulfide. There was no oxygen in it, since a couple of billion years ago there were not even potential sources of this gas - photosynthetic organisms. At the beginning of its history, our planet was inhabited by anaerobes. Of course, they produced a certain amount of oxygen, but all of it went to the oxidation of gases and dissolved compounds. This process was completed by the beginning of the Paleoproterozoic era: all that could have already been oxidized, and oxygen began to accumulate in free form. A rearrangement of forces took place: single aerobic organisms still began to prevail in the biosphere, displacing anaerobes. The atmosphere turned into nitrogen-oxygen, and an ozone screen formed above it. Now cosmic rays could not penetrate the surface of the planet, the greenhouse effect characteristic of earlier eras decreased and the climate changed dramatically.
Before the planet Earth appeared with its continents and continents, the land on it was a monolith, called by scientists Rodinia, and the body of water was a single ocean of the World. For the first time, Rodinia fell into pieces about seven hundred and fifty million years ago, after which geography changed several times dramatically. In particular, thirty million years ago, continents formed, which we can still see on the world map. In addition, scientists suggest that the movement of lithospheric plates will lead to a new unification of parts of the land into a single continent, which has even come up with a name - Pangea Ultima. It will happen presumably in two hundred million years.