Everything that concerns the emergence and development of our common home - the Earth, cannot be ignored by everyone who considers himself erudite and civilized. And if during the training everything was quite clear - teachers and teachers (thanks to them), explained well, then with further in-depth - not everything is so smooth. It turns out that some "capital truths" contradict not only the logical state of affairs and common sense, but also indisputable facts. Not all, fortunately, this applies to objects. But geology, with its tangential sciences, is, unfortunately, hooked. Perhaps that is why there are so many specific terms that are beyond the control of ordinary mortals, to make it easier to retouch what experts are unable to explain.
What about those who are interested in the truth
It is much easier for those directly involved in geological sciences. The main thing here is to correctly guess which current or "luminary" to join, everything else is almost decided; even during training.
But what about amateurs who are also interested in the truth. It is the truth, not what is in trend today. They are not interested in either dubious authorities or "generally accepted" thoughts. How should they behave?
And there is probably only one way out, to introduce certain rules (restrictions) - and question everything. Believe in what you do not know well, doubt what you know well. Make friends with the terminology as much as possible. And take into account the opinions of others - it can be decisive. Even the most ridiculous of them is important. It will either show the right path, or warn against the wrong. And the main thing is to rely only on facts.
Everything has its time. So let's decide where to start. Wherever it goes, unfortunately (or fortunately), contradictions (sometimes diametrically opposite) are torn apart. If not mobilists from fixists (and it is still very early to write them off to the archive), then about the origin of carbohydrates - organic and inorganic; the temperature in the center of the planet is predicted from almost absolute zero to hundreds of thousands of degrees and above; the same goes for ... And who to believe? Everyone is sacredly confident that they are right. As the people say: "Each frog praises its swamp." And so that this "swamp" does not "suck in", let us distance ourselves from this with the right to doubt and begin to unravel the tangle. With the hope (necessarily) that this is the thread of Ariadne.
Let's start with what is least realistic to prove, although there is logic in this statement. According to Vladimir Ivanovich Vernadsky (1863-1945) back in the 30s of the last century, the temperature is rapidly decreasing towards the center of the planet. This statement fits into the cosmogonic theory of Otto Yulievich Schmidt (1891 - 1956) about the "cold" formation of planets from a gas-dust cloud. Perhaps this is so, but only with the amendment that this does not apply to our solar system - its components are too different in age. The same Venus, in comparison with other planetary bodies, is much younger - even in human existence it was called a "bearded" planet. Better to draw a parallel with supernova formation. And the substance that lies in the very depths of the planet is most likely to be found in the asteroid belt, or to see the result of its action in regular flares on Mars. But these are all guesses, not even hypotheses. Therefore, over time, you will need to look at them from a different angle.
Further, if possible, we will try to touch the more mundane, accessible "to the touch" and understand the nature of the earth's crust.
What do we know about the bowels of the Earth?
The earth's crust, like a solid and cooled shell of the planet, according to the classical scheme, is divided into three layers: sedimentary, granite and basalt.
The thickness of the sedimentary layer is not the same. It ranges from 0 to 15 km. The thickness of the granite layer is from 5 to 15 km. The basalt layer is 10 to 35 km thick.
All these three layers are separated from the upper mantle by the Mohorovichich line, which determines the thickness of the planet's crust in different places on land and in the oceans. The average thickness of the crust on the continents is 35 km. But in mountainous areas, for example, under the Pamir or Andes, it reaches 70-80 km. Ancient platforms are 30 km thick. A relatively thin layer of the earth's crust beneath the oceans. It reaches a thickness of only 5-6 km. There is a big difference between the continental and oceanic crust. Mainly it is that there is no granite layer under the oceans. If we compare the thickness of the sedimentary layer of the land with the oceanic, then the latter will still be less - in the region of 1 km. Many areas, such as the Pacific Ocean, have no sedimentary layer at all, or in the worst case it is very thin. (The reason, perhaps, lies in his "youth" and too aggressive growth). In the full sense of the word, there is no precipitation in many oceanic faults.
If we talk about the earth's crust, then we mean the hard shell of the entire planet. But in order to understand the essence of the difference between the continental crust and the oceanic crust, it is necessary to analyze in more detail the available data separately about one or another.
The continental crust has an average thickness of 35 km. But it also has a thickness of 70-80 km. This means that there should be places thinner than 35 km. What are the areas of increased and decreased thickness? "As a rule, - noted in special literature - on the continents, the earth's crust is thicker under the young ridges and thinner under the lowlands."
The dissimilarity of processes in the earth's crust
What is the reason for the unevenness thicker than the hardened shell? First of all, one should turn to time. What is older in age, mountain structures or lowlands? How does time affect the evolutionary development of the planet and, in particular, its hard shell?
Let us turn to the conclusions of what V.V. Belousov (1907-1990): "... if it follows from geophysical data that the earth's crust is thicker under young folded zones, thinner under ancient folded zones and even thinner under ancient platforms, then, obviously, it is necessary to conclude that over time there is a decrease in the thickness of the earth's crust. " (Given the specificity of mountain building processes in each geological epoch, this conclusion should probably be questioned).
It has been established that some areas, which were platforms for a long geological time, recently (10-15 million years ago) suddenly regained their mobility and mountains began to grow again within them. They are zones of tectonic activation. This, for example, the Tien Shan, which grew as a result of a significant increase in tectonic vertical movements in the Neogene and Quaternary, whereas before that - throughout the Mesozoic and in the Paleogene - this area was already a platform. Geophysical methods show that the crust in such activation areas is very thick, twice that of the crust on the platforms. "This means that the activation of tectonic movements is associated with an increase in the thickness of the crust" - the conclusion of the same author.
The question is, what depends on what: activation of tectonic movements from an increase in the thickness of the crust, or the thickness of the crust from the activation of tectonic movements?
Simply giving an answer to this question is not so easy to believe in its true meaning. First of all, it is necessary to look into the depths of time and turn to many other data on the evolutionary development of the planet. In addition, a logical approach to deflecting obstacles to research is needed.
The earth develops according to the laws of dialectics
According to the dialectic of nature, nothing is eternal and permanent. Even F. Engels (1820-1895) argued that there is an eternal circulation of matter in the Universe. According to him, the eternal cycle in which matter moves occurs during such huge periods of time that cannot even be measured by earthly years. In this eternal cycle of matter, many suns and lands arise and die.
Separate, concrete forms of existence of matter, whether small particles, or gigantic celestial bodies, all the same pass, temporary. Matter itself - mobile, changeable - exists forever.
What is our planet like? The Earth is a grain of sand in the infinite space of the Universe, of which there are countless, as a product of material education. If we still do not know about many things, this does not mean that we should not adhere to the truth - the principle of the only materiality of the world. The processes of material transformations that take place on our planet are inherent in all other similar material education.
Hence the conclusion: we must consider certain phenomena occurring on our planet in accordance with the laws of the dialectics of nature. This means that our planet also has the beginning of its life path.
Since the question, at the moment, is about the nature of the earth's crust, research will be conducted within the framework of this.
In search of the original stronghold
If the continental crust has a different thickness, there must be a different time of its origin. What is the older platform or geosyncline? The question is clear: the geosyncline is younger, because it formed at the site of the deflection of the earth's crust.
What was the earth's crust at its initial origin, if the platforms, seemingly the most ancient parts of the earth's crust, do not correspond to our idea that the planet's surface was once molten. According to geophysical studies: “On the platforms, strong folding is observed only in deep folds of the crust - in the crystalline basement. But this folding is ancient. It was formed even when there was a geosyncline in the place of the platform. Then the earth's crust solidified, a platform was formed, and the calm occurrence of younger sedimentary rocks reflects an already inactive state. "
So what happens? The platform, as an area of the earth's crust, which should be a sample of the pristine type of hard shell, also experienced tectonic movements, which led to the formation of folding. Where to look for reference points, from where it would be possible to begin research on the further course of the development of the earth's crust.
The fact that the earth's crust at the initial stage of its development was in a molten state is indisputable.
The reference points should be those land areas in the platform area that have not experienced deformation and have a near-thickness granite layer, not taking into account deviations from the horizontal.
The next question, as a complementary factor in this study, should be resolved about the nature of mountain structures, about the mechanism of their formation. Until now, this issue has not been resolved. Many hypotheses and various assumptions arose around this question.
Individual mountains or entire mountain systems are material formations from the body of our planet.
Studies and studies of various areas of the surface of our planet show that the mountains on Earth are not the same in age. There are old and younger mountain structures. As it is already considered, and it is quite natural, that the mountains grow on the site of the former geosynclines in tectonic zones. On the surface of the earth's crust, there are, for example, folded zones. It is known that they were formed at different times. There are Caledonian folded zones, in which the layers collapsed into folds at the end of the Lower Paleozoic, that is, about 400 million years ago. These zones include the highlands of Scotland, the Northern Appalachians in the USA, the Sayan Mountains in Russia, etc. The later folded zones are called Hercynian or Variscian. In them, the layers crumpled into folds at the end of the Paleozoic era, that is, 200 million years ago. These include the South Appalachians, the Urals and a number of mountain ranges in China, etc. Finally, the youngest are the Alpine folded zones - the Alps, the Caucasus, the Himalayas, the Cordillera of North America, the Andes of South America, etc. 35 million years ago and even later. There are also very ancient, pre-Paleozoic folded zones.
The conclusion drawn by scientists is questionable: "After the formation of a folded zone, the movements of the earth's crust in its place usually fade and a platform is formed here." (But is it always? And exactly when? And about sedimentary rocks ...)
This chronology shows that the mountains did not arise at the same time. But what if you follow the path in the opposite direction? What would our planet look like? Would its surface be flat? Not. Taking into account the currently existing mountains and removing them, we will thus not achieve the smoothness of the surface, going back many millions of years ago. Currently, on the surface of the planet, we are areas that we call the crystalline basement. It is a relatively flat area covered with a sedimentary layer. Let's take this layer as well. It turns out that not everything is smooth under it either: there is also folding there, alternating with equal sections of the crystalline platform.
The question is, where could so much of the substance that we removed in order to get to the crust of initial origin come from? But both the sedimentary cover and the mountain chains are all superstructures on a solid foundation, all this is catching up from above, not from below. And if you take into account the still elevated plateaus, like areas of land flooded with lava? Let's start again with the question: what is a geosyncline? After all, is it the cause of the creation of mountains?
The answers to the riddles, perhaps, in the development of the geosyncline?
According to the established concept, a geosyncline is an elongated zone of the earth's crust of intense movement, which manifests itself first in the subsidence and accumulation of a large thickness of sedimentary rocks, and later in an uplift, which is accompanied by the formation of folded mountain structures. During folding, earthquakes and volcanic activity are especially intense.
If low places are formed, and even in the aquatic environment, then it becomes clear about precipitation. But what constitutes the process of deflection and why does it arise - the main task on the way to the denouement about the nature of mountains and the mechanism of their formation has not yet been solved.
Suppose that after the melting of the surface layer of the Earth, the cooling of the substance began, which gave rise to the origin of the planetary crust. This means that the surface should be smooth without any mountain structures and hills.
That the Earth at one time underwent a melting stage, the opinions of many scientists coincide. But there are also many opponents.
What are the reasons that can cause the sinking of a land area, moreover, rather large in size, tens of kilometers in width and hundreds in length? (For example, these can be geosynclinal regions such as the Tien Shan, Altai-Sayan, Antilles-Caribbean, or even geosynclinal belts.)
Is it mechanical deformation under its own weight or something else? It is very difficult to judge the processes that took place at the initial stage of the planet's development. It is easier to understand the essence of such, if we turn to the same processes that are currently taking place. Let us turn to facts, not thoughts about them, for help.
It's easy to say so. But it is not easy to comprehend on a serious basis the truth of the phenomenon that took place. The term "sinking" entered the lexicon as a completely and 100% understandable word, like the word "wind", the comprehensive meaning of which is fully understood.
Do we understand the truth of the word "sinking" of the earth's crust, so that we can use it with the same correctness in solving the still unresolved issues related to this phenomenon? No, we don't understand. We accept this word mechanically, borrowed lightly from the experience of life. And we believe this, we believe, as we do to ourselves. And since we believe, then we do not even have any doubts about its reliability and truthfulness.
And this concept should have been questioned for a long time, pondered and come to a firm conclusion: does the semantics of the word correspond to the phenomenon that actually happened or not? Or maybe the phenomenon that we call sinking should be replaced by a completely different term, more consistent with material movement? But then how do not say, but on the site of the once former plain formed the deepest depression. This is already a fact, not a fabulousness, so you cannot give up on this and cannot do without a concept of it. And if so, then an appropriate name is required.
The existing name does not fit in any way, for the term "sinking" does not in any way correspond to the idea of unshakably acquired experience. In place of this, something more appropriate should be thought of.
None of the naturalists have yet proved that at the bottom of a subsided land area, he found identical rocks identical to them with the rocks surrounding this place. And he will never prove this, even if he cleared all the depressions of the globe from the sedimentary cover. After all, the concept of "sinking" of any part of the earth's crust paints in our imagination a very real picture: a flat area or so suddenly, for reasons unknown to us, retaining its previous position around the circumference, begins to bend in the central part. Everything that was there begins to sink along with the soil. The deepening is getting lower and lower. Slow or fast, it doesn't matter. And we know that on the globe there are a lot of huge areas where subsidence took place and where many kilometers of sedimentary rocks have accumulated. There are many large ones, and even more small ones.
And so, according to our established ideas, the imagination can paint in the mind an eerie picture of this phenomenon. It's no joke to imagine a land area sinking to a depth of 12,000 meters, as is the case in the Caspian lowland. If this subsidence occurred somewhere in the Carboniferous period, then one can even hope that some remains of fauna or flora should remain at the bottom there. After all, there are imprints of leaves in stone rocks, but miners find charred trunks of ancient ferns.
Our imaginations allow us to fantasize, but there is not one milligram of benefit in searching for the truth. There is no benefit here, but only harm and deliberately erected barriers to the knowledge of the truth. A wrong start on a wrong basis never leads to truth. Therefore, even the imaginary picture of the sinking process does not correspond to reality in any way. Even if the dense forests surrounded the Caspian Sea from the north and north-east, that is, in the place where the modern lowland. But they gave way to the lowlands and were in no way absorbed by it.
There are similar depressions even now with the existence of a very observant creature, but they are inaccessible to the human eye - at the bottom of the oceans.
So, the processes that have shaped the appearance of our planet since the inception of the crust have not disappeared anywhere. Everything has its time. The conditions for making up the earth's crust have changed, and mountain building processes have been corrected. And so the principle is the same, only in the "sea", more precisely oceanic, version. And what is happening on the continents are only reduced copies of what happened in past eras. And in order to understand the past in more detail, or at least a little look into the future of the planet, you need to consider more key moments from the life of the Earth. Perhaps, this too, is the key to unraveling the location of useful deposits on the planet.