A photo from open sources
It is likely that over seven hundred million years ago, ours the planet was all covered with ice. And if this is really true, then many geophysical paradoxes discovered recently. So, some scientists speculate that that in the very distant past, our Earth at least three times fully covered glaciers with more than a kilometer of thickness. AND here a few years ago the American geophysicist Harland unexpectedly for all found that located in tropical latitudes ancient coastal cliffs that have come down to us from the Neoproterozoic period, covered with remnants of ice. The paradox is that ice in tropical zones can only be seen in the mountains, and even then at a height not below five kilometers. The second paradox is the fact that, as in layers pie, along with such strange sediment, Harland discovered unusually iron-rich deposits, alternating with layers of ice. This is more than strange, because when in the atmosphere Earth has free oxygen, open iron immediately oxidizes, and deposits found were not exposed to oxide, although there are reasons to believe that the composition of the atmosphere in the Neoproterozoic era was almost the same as now. Another riddle is observable ubiquitous strange pattern: these sediments in tropical areas necessarily covered with a thick layer of rock, very rich carbonate. Experts know that carbonate from seawater released during its heating, dissolving during cooling. Picture it turns out like warm tropical waters at some time cooled, and then warmed up quickly enough due to the increase temperature in the air. In addition, the analysis of carbon isotopes in found carbonate deposits involved in biochemical life processes and therefore indicating the existence of life or its absence, led to the conclusion that iron was in the rock included during the very long, stretched over millions of years, breaks when the planet was completely lacking biological a life. But what could have caused such huge breaks in evolution? Attempts to explain such paradoxes have been made. by many scientists. So, in the 1960s, the geophysicist Harland was the very first suggested that in the Neoproterozoic era the Earth froze, and even in the hot tropics. Almost simultaneously to this conclusion, although based on other facts, the Soviet geophysicist Mikhail came Budyko, one of the first to model the Earth’s climate. According to him calculations, with a significant decrease in atmospheric concentrations carbon dioxide, a sharp decrease in the greenhouse effect is possible, and means – air cooling, causing the spread of ice and snow towards the equator. And such an increase in the area under ice and snow, reflecting sunlight, can cause more cooling. And already a similar chain reaction, in the end account, leads to freezing of almost the entire surface of the Earth. Budyko called his solution to this climate equation “solution white planet “or” ice catastrophe. “But then what interrupted is this ice age? In the 90s of the last century by American geologist Joseph Kirschwink suggested that the shift of tectonic plates caused the appearance of a large number volcanoes that began to throw into the atmosphere of a frozen planet a huge amount of carbon dioxide. In our atmosphere completely frozen planet, which Kirschwink called the “snowball”, this carbon dioxide began to accumulate until the greenhouse effect “caused by him did not raise the temperature in the air before the meanings before which the ice began to recede.
Kirshvink came to this conclusion, trying to find out the nature mysterious deposits of iron on glacial sediments. According to him theory, iron was dissolved in the oceans at a time when in our atmosphere still had practically no oxygen, and with it the appearance in the atmosphere and therefore in water, iron began fall to the ocean floor. Kirshvink’s hypothesis caused rather cool reaction, however in the next decade two facts were revealed that testified in her favor: these were the said carbonate deposits and their isotopic composition. Scenario glacial disaster, according to scientists, looked like this: seven hundred million years ago all the land areas that made up present continents were grouped mainly around the equator, and the seas at the poles were completely covered with ice. Flow rate heat from the sun was six to seven percent lower than now, and this made the climate unstable to possible sudden changes. Such changes could be a sufficiently long break in volcanic activity, leading to a decrease in inflow to carbon dioxide atmosphere. Because then the continents lay near the equator, there was no ice on them, and such land should have been absorb carbon dioxide even at lower temperatures. And this led to an even greater decrease in the “greenhouse effect” and lower temperatures, leading to the expansion of areas under the ice. The return path of melting ice was also an avalanche transition, and almost instantaneous on a geological scale. The heavy rains, enriched with carbon dioxide, quickly decomposed rocks, opened as a result of melting, and demolished decomposition products in oceans, where the carbonate content began to increase, gradually Settled at the bottom. This explains his current discovery. So far, only one paradox is inexplicable: these are breaks in “biologically active “layers of rock, although they may have become a consequence of the repetition of the icing – thawing cycle, which scientists counted at least three. But how is life on earth after each cycle did she manage to resurrect? Was originally put forward the assumption that this happened due to enormous adaptability protozoa, however, such an explanation was refuted by biologists. Some complex computer scientists assure in almost all cycles on an icy planet there remained “oases” free of ice. And it was they who supported life in its then forms. Today our planet seems safe. Most continents are located near the poles, however, the movement of tectonic plates, and hence the continents, never does not stop. And, quite likely, after millions of years they are again are grouped at the equator, and then another icing will occur. One can only hope that, just as in the past, our the planet will survive and enter a new phase of its extraordinary stories.
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