Each geological period of the planet's development left its imprint, but not everywhere on the earth's surface, but in places, in separate places. And even if we could even imagine that at one time modern continents were completely covered with water, and then the sediments that arose then could not spread everywhere, but only localized, that is, in those places where they broke through to the surface.
And therefore, considering the modern distribution of sedimentation, scientists come to the conclusion that the sea has repeatedly advanced and retreated to land. Is this true? This is doubtful.
The importance of the external environment during an eruption
Somehow there was an opinion in science that the existing alternation of layers of sedimentary rocks is determined with the alternation of retreat and reverse advance of the sea. To ask the authors of this opinion, where could sea water bring such a huge amount of material to create strata out of it only in certain places? You can be sure there would be no answer.
The fact that the largest strata of sedimentary rocks lie in the troughs of the earth's crust does not mean that water is given the leading role. Of course, during the emergence of vast depressions in the earth's crust, masses of water were concentrated there. But the water in such depressions played only the role of the environment, and not the cause of the occurrence of sedimentary material.
The environment itself for igneous rocks is of no small importance not only for the distribution of material on the surface, but as an influential factor on the final structural formation. Not all chemical compounds, that is, minerals, acquire the same appearance in water and in air after an eruption in a red-hot state.
This is also one of the necessary factors for understanding the very nature of the formation of the earth's crust.
Faults as shapers of the planet's appearance
In order for the prepared amount of matter in the bowels of the planet to appear on the surface, it needs a free exit. And such a way out is the resulting break in the hardened shell of the previous outpourings. The cause of the occurrence of faults will be those tectonic forces that, roughly speaking, are directly related to the accumulation of material that should be thrown from the depths to the day surface. Any eruption, whether magmatic or mountain-forming, or gaseous, is an act of extinguishing the intra-planetary pressure.
But it is not done as soon as the tale says. The variety of tectonic movements is very large. There are cases when a portion of the intra-planetary matter appears on the surface almost at lightning speed, and it also happens that the very preparation of the ejection in the intended place takes hundreds or even more than a hundred years. Let us recall a volcanic eruption today, as in Brazil, when in broad daylight a volcano formed on a flat corn field. And the newly appeared island of Surtsey off the coast of Greenland?
These are just a few minor in scale, but they also give us a complete picture of more grandiose events in the past. It has already been mentioned that all significant efforts to shape the appearance of the Earth and the accumulation of tectonic actions for the modern period are concentrated in the water basin. All varieties of the same mechanism of the appearance of deep matter on the surface are not so easy to consider in a brief summary.
It is most easy to understand and reveal the mechanism of the appearance of terrestrial matter on the surface of later geological periods, especially in the last stage of determining the forms of modern continents. Most of all, it is the hardships of the Proterozoic and Archean eras. Adhering to the general principles of the dynamic movements of the original earth's crust, in modeling the mechanism of the planet's expansion, some of the data sometimes look more than fantastic.
The most ancient parts of the planet
Crystalline foundations are considered to be the most ancient parts of the earth's crust. These are scattered all over the world. At the same time, they are the cores of the continents.
Simultaneously with the consideration of the question of the origin of the crystalline shields, it is necessary to keep in mind the platforms that are close to the former.
According to the scientific definition, a crystalline shield is a large area of the earth's crust, on which Precambrian rocks protrude to the surface. In rare cases, they are covered by an insignificant stratum of sedimentary rocks.
The platform already has some distinctive features. This is a large area of the earth's crust, where two geostructural levels can be distinguished: the lower one is crystalline and the upper one is sedimentary. The platform is characterized by the absence of significant folding processes, oscillatory movements prevail.
The common in these two geological formations will be a crystalline massif. But both belong to the Precambrian, that is, to the Proterozoic and Archean eras. If they are indiscriminately attributed to a time of more than 5 billion years, the concept of their specific age will look very vague.
The platform has a crystalline basement and has a thick sedimentary cover. The shield has only crystalline rocks. Yet which of them will be older and which will be younger? The very distribution of sedimentation already indicates a difference in age.
If a scientist were to ask such a question, of course, he would have resorted to modern methods for determining age from radioactive isotopes. Without such a method, one has to use the comparison method in combination with the known one.
Let's take into account the known fact that any sedimentary rocks, no matter how loose or cemented, are an erupted mass from the deep bowels of the planet. Here we will not take into account all sorts of processes of their redeposited, which actually took place, although not so significant on a global scale. The most controversial issue remains the question of crystalline rocks. They are also not all the same age. Among them there are even more ancient and younger ones.
We will assume that the most ancient crystalline rocks of all such will be granites and the like. (Let it be verified). In this regard, one should take into account first the power and nature of occurrence, and then the prevalence on a global scale. Their block structure also plays an important role.
And in science, it is probably wrongly accepted to consider individual block structures of granites as intrusive bodies. Intrusion is around them, but they are not intrusive.
Translated from Про формування планети - речовиною з її надр
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