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The great kingdoms of nature evolve: air, water, earth

The great kingdoms of nature evolve: air, water, earth


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The great kingdoms of nature evolve: air, water, earth

When scholars set about defining the criteria for dividing the History of the Earth into eras, periods and epochs, at the beginning of the early nineteenth century, not being able to have the elements to create a absolute value scale, they had to limit themselves to onescale of relative values geological formations on the basis of their reciprocal positions, their petrographic characteristics, the presence of fossils, etc., assuming that certain characteristics were sufficiently uniform in the various continents, so as to be able to correlate the various outcrops. Only in the last decades of the past century, thanks to the presence of radioactive elements in the rocks, it was possible to determine, even with a good approximation, the age of the various formations.

The subdivision into Geological Ages begins with theEraPaleozoic or Primary, that is, that Era in which, according to the first observations, life appeared on Earth. Therefore they were attributed toPaleozoicthose lands in which fossils were found, believed at the time to represent the remains of the first organisms.

Underlying these formations a whole series of terrains was identified consisting mainly of eruptive and metamorphic rocks, that is a defined complex "Azoic"in the presumption that it had formed before the appearance of life, but with the deepening of the research it was ascertained that even the upper part of this complex had organic remains belonging to species already sufficiently evolved, so much so as to suggest that the life represented by unicellular microorganisms he had to be there a long time ago.

It would have been logical to lower the lower limit of the Paleozoic, in order to include even more ancient formations, instead it was considered more practical to name Pre-Paleozoic or Archaeozoicall that underlies the Paleozoic.

PRE - PALEOZOIC (table "Pre-Paleozoic time scale")

In recent decades, with the interdisciplinary results of the sciences, from astronomy to geology, really decisive progress has been made to determine the ways in which the current structure of the Solar System and therefore of the Earth has been reached, in particular it has reached determine the age of the planet with greater precision, estimated at around 4.5 billion years.

Since the base layers of the Paleozoic can be dated to around 500 million years, the first 4 billion years on Earth were used for the formation of a first earth's crust as the temperature lowered outside the planet and consequently all those processes concerning the terrestrial physics, in particular, a cycle began that from then until the days has been continuously repeating:soil erosion à transport and storage of material à sinking with alteration of the soils à lifting with consequent orogenetic processes à erosion of soils.

Identifying and reconstructing these cycles is, among other things, the function of geology, with particular regard to the three interdependent environmental domains: Air, Water and Earth

As seen in previous articles on Geology and the environment, during the pre-paleozoic the conditions were created for the transformation of the primordial atmosphere to reach the current gaseous composition, a transformation based on two fundamental processes:

1) air purification from those elements that, due to the high temperature, were initially in the gaseous state in significant percentages, while they are currently absent or in minimal traces, thanks to the condensation of those products that are currently in the liquid or solid state in the atmosphere. The most striking effect was undoubtedly the condensation of water vapor, the origin of which is to be found in the ice present in the cosmic cloud, which turned into vapor during the heating of the latter in the aggregation phase of its components. It has the same origin as ice that still wanders in space in the form of comets or asteroids that are discovered and photographed daily by satellites

During the first hundreds of millions of years, planet Earth's capture of cosmic material must have reached remarkable dimensions.

In the early days, at least for 1 billion years, the intense volcanic activity that persisted on earth represented a continuous source of gaseous and solid elements, in the form of lava and ashes, destined to be distributed over extensive terrestrial surfaces by atmospheric agents and at the same time conditioning the meteorological parameters.

2) "Oxygenation" of the waterswith the subsequent passage of oxygen from the water to the atmosphere, by the unicellular microorganisms, whose biological cycle also includes the emission of oxygen as a final result. It was a long process that led to the current presence of 21% oxygen in the air, allowing the life of living beings as we know it. We do not know when the current environmental conditions have been reached, but in any case before the appearance of a fauna already evolved on the zoological scale, such as that found in the higher soils of the Pre-Paleozoic.

The rains in their fall were enriching with elements present in the primordial atmosphere so that the latter, with the passage of millions and millions of years, has been purified. At the same time the rain washed away the first earth's crust, partly returning to the state of vapor given the temperature of the soil of many regions and partly accumulating in the depressions to collect in ever larger quantities and thus originating the Seas and Oceans, which have always exalted men and conditioned the evolution of humanity and civilizations.

Where did life on Earth begin and how did it develop? For us it is too obvious to answer that life originated in the waters, because now the study of Paleontology leads us to this certainty, but what strikes us is to note that man for several millennia had reached the same conclusions based exclusively on his own intuition and following the following logical thread: life could only begin in the waters, to subsequently conquer the earth with vegetal forms that would then represent the nourishment of the first herbivorous fauna also coming from the waters. Once the presence of herbivores on the land emerged, the expansion of carnivores took place.

Returning to the early stages of the formation of basins, with the enrichment of marine waters by atmospheric and terrestrial washout, enormous quantities of minerals were accumulating in the seas for millions of years, both in the form of soluble salts and in the solid state on the seabed.

A doubt arises: if the environmental processes had come to other results, that is, to other organoleptic compositions of water and the atmosphere, would a life different from the one we know have developed? We cannot exclude it, indeed many data make us answer in the affirmative not only with regard to our planet, but also for other worlds among the billions of bodies scattered throughout the Universe. On the other hand, how many theories considered to be the result of the science fiction of past centuries have proved not only outdated by the progress and results of scientific research, but, most terrifying thing, that we are now convinced that any science fiction theory or intuition will certainly be confirmed by scientific advances: it's just a matter of time.

In the meantime, what happened to the earth's primordial crust? We know very little, not for the scarce extent and thickness of the geological formations, but for the state of alteration of the rocks given the metamorphism "to which they have been subjected for over 4 billion years.

On the basis of the lithological types and the rare fossils that can be identified, the complex has been divided into two parts, the lower one called "ARCHEANO" and the other above it called "ALGONCHIANO" which have an equal duration of time - about 2 billion years - and the limit between the two is marked by a discrepancy.

The Archean lands they are represented by eruptive rocks such as granite, diorite or metamorphic syenites such as gneiss and micascists. In the upper part, phyllites, quartzite limestone and conglomerates of glacial origin prevail, thus believing the theory that the earth in the first billions of years had always been affected by relatively high temperatures. The only recognizable fossils are bacteria.

The Algonquian (or Pre-Cambrian) formationsthey are characterized by are characterized by sedimentary rocks such as conglomerates, sandstones, limestones, while the presence of metamorphic and eruptive rocks are limited. As far as fossils are concerned, remains belonging to Algae, Protozoa, Coelenterates, Molluscoids, Echinoderms, Molluscoids, Gastropods and Arthropods, etc., are very widespread, so life 2,500 years ago was already considerably developed so as to be considered the basis of a large development in the Paleozoic with evolutionary processes that led to the establishment of plant and animal species both in the waters and in the emerged lands.

The distribution of pre-Paleozoic formations affects all continents, but before pointing out the main outcrops, it should be noted that the current geographical positions of the Pre-Paleozoic formations and subsequent eras do not necessarily correspond to the places where they were formed as a result of movements of translation of plates of the earth's crust, as we will have the opportunity to see in the next articles.

Given the compactness of the pre-paleozoic plates, so rigid that they were no longer affected by the orogenetic cycles that occurred in later times, they have been designated as "shields"to underline their role as substratum assumed in the structure of the continents.

Plaques or cratonic areas have been identified everywhere, such as the Canadian shield (North America and part of Europe), the Baltic shield in Northern Europe and the Siberian shield in much of Asia. Finally, a whole series of outcrops that embrace South America, Africa, Arabia, Peninsular India and Australia which represent the fragments of that great primordial craton called Gondwania, to which we will return later.

These broadly speaking are the basic elements for a period of the Earth of 4 billion, that is 89% of the time elapsed since the formation of the solar system and therefore including our planet. The information available is scarce for the reasons set out above, but nevertheless many fundamental considerations can be made on this enormous time frame. These are considerations concerning the climate, the birth in life and the evolution from the first unicellular forms to the more complex and differentiated ones, the evolution of the earth's crust and the traces of the first orogenesis.mechanisms"whose effects are clearly visible in our day, conditioning our life. We will talk about all this in the next issue.

The most striking effect was undoubtedly the condensation of water vapor, the origin of which is to be found in the ice present in the cosmic cloud, which turned into vapor during the heating of the latter in the phase of aggregation of its components. It has the same origin as ice that still wanders in space in the form of comets or asteroids that are discovered and photographed daily by satellites. During the first hundreds of millions of years the capture part of the planet Earth of cosmic material must have reached remarkable dimensions.

In the early days, at least for 1 billion years, the intense volcanic activity that persisted on earth represented a continuous source of gaseous and solid elements, in the form of lava and ashes, destined to be distributed over extensive terrestrial surfaces by atmospheric agents and at the same time conditioning the meteorological parameters.

Dr. Pio Petrocchi


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Comments:

  1. Meztilabar

    as they say, To exist without benefit is an untimely death.

  2. Mbizi

    All about one and so infinitely

  3. Yozshusida

    It's a shame I can't speak now - very busy. Osvobozhus - necessarily their observations.

  4. Thurhloew

    yeah ... you're right



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