From the traces left on the earth's fossils and stones, the appearance of "the beginning of the earth" and a new way of thinking about "extraterrestrial life form" are brought

ByMartin Heigan

The history of the earth is old, and it is thought that the first shape was made about 4.5 billion years ago. At that time the earth was a burning hell who could be said to be a "melted magma mass", but it was thought that the sea and the land were born and the life was born, an environment where water can exist can be born gradually as the temperature drops Although there are fossils left in the strata that are classified as the oldest in the Earth, the theory that existed in the Earth at the earliest stage was supposed to be supported by the first life I am coming. About that situation, the science media "Quanta Magazine" operated by the Simons Foundation of America is summarized.

Fossil Discoveries Challenge Ideas About Earth's Start | Quanta Magazine
https://www.quantamagazine.org/fossil-discoveries-challenge-ideas-about-earths-start-20180122/

Humans have kept records of each era by using symbols and letters, but it is only in the past several thousand years ago that it is possible to go back to the past by this method called "prehistoric era". There is no way to know the appearance of the previous era from the record, but insteadSurvey geologyIn this way you can classify the temperature of each era, the composition of the atmosphere, the characteristics of living creatures and plants that were inhabited at that time, and can honor the history of the earth. The era classified by this methodGeological ageIt is called an era where you have heard somewhere, such as the oldest age "Horse Royal", the Cambrian dynasty where life has diversified at once, the Jurassic in which the dinosaur lived, "Cretaceous" The classification is lining up.

The oldest crust that is currently found on the earth is found in the dry and sunny areas where northwest Australia drifts. On a coastal city · a small hill in a car from Port Hedland for a while,Pilbara CratonCalledKrathon(Stable land landing) is exposed. This Krathon is left as it is that formed about 3.5 billion years ago, about one billion years ago when the earth was made.

In this Krathong, a layer of sediment called "Apex Chert" has been found. When observing the orangeish cream colored rock collected here with a microscope, you can see the tubular object there. This is thought to be a fossil of living things that seems to have lived 3.5 billion years ago and is seen as being the trace of the oldest life currently found on the earth.

ByJames St. John

However, some surveys conducted in 2017 may indicate evidence of a trace of life older than this. Potential to include life forms of 3.7 billion years ago, 3.9 billion years ago, and 4.42 billion years ago by mining and crushing old crusts by methods such as drilling, crushing, laser blasting and detailed investigation There are traces of revealed.

In the age of the Hidari period just after the earth was born, the primitive earth was a burning hell dominated by a volcano, and it has been thought that life does not exist as it was undergoing repeated bombardment from other planets It was. Also, shortly after the birth of the primitive Earth, the celestial body "Tia" of the same size as the current Mars collides with the earthGiant ImpactIt is thought that a part of the crust that evaporated with energy at this time was released to outer space and later became to form a moon. Besides, the reason is that it is hard to imagine that life existed in a very primitive Earth due to the influence of intense solar wind blown from the young sun.

On the other hand, many geologists believe that the earth has been cooled from an earlier stage than conventionally thought, and water existed. From the traces found so far, it is suggested that some of the Earth's crust has cooled and solidified by 4.4 billion years ago. In addition, these ancient rocks contain oxygen, which indicates that water was present as a liquid for 4.3 billion years ago. Elizabeth Bell, a geochemist at the University of California, Los Angeles said, "In fact, the world at that time might have been closer to what was in the contemporary world than it was thought. There is a possibility that there was a stable crust, it is now "not misunderstood" to think that the world in which you can live and some kind of life existed. "

Bymobil'homme

Small crystals called "zircon" that came to be discovered since the beginning of the 2000s are supporting the theory. Zircons that are only as large as one dot of the liquid layer monitor have left a trace of a cool, damp, and possibly lively world spreading to the earth 4.3 billion years ago about. We have found this zircon even in Pilbara craton, and we know that it contains tornado-like fossils.

In March 2017, a geologist at the University of London Dr. Dominique Papinot and a student Mr. Matthew Dodd found a trace of the ancient earth in the fossil found in Quebec, Canada. This structure called "Nuvvuagittuq (Nuwowigituc) Greenstone Belt" is to convey the figure of the seabed of the primitive Earth to now. The width of the fossil is about half of the human hair and the length is about several millimeters. It was discovered from the seafloor strata. This structure was made from iron oxideHematite(Red iron ore), which Dodd says that colonies formed by microorganisms gathering became fossils as they were until 4,200 million years ago.

It is thought that this microorganism was inhabited around the spout ejected from hot water from the ocean floor, and similar structures were found in the modern submarine. Mr. Dodd also found a tubular structure near here and found a small carbon ring "rosette" containing organic materials there. Rosette may also be formed by non-biological processes, but Mr. DoddApatiteWe discover a kind of mineral called apatite. This is a discovery that may indicate that biological activities were taking place.

ByNOAA Ocean Exploration & amp; Research

Dod and colleagues also analyzed carbon isotopes in structures. In general, because organisms tend to choose the lighter isotope even for the same element, carbon 12 is often found more often than carbon 13. As many lightweight isotopes were found also from structures near the rosette, there are still results showing that life existed there.

Later in September 2017, the team of Professor Yuji Sano and Associate Professor Tsuyoshi Komiya of the University of Tokyo visited the sagittal rock called Saglek Block in Labrador, Canada, and found a structure showing the traces of organisms of 3.95 billion years ago In addition to reporting that Australia's University of Wollongong University professors Allen Natman and others reported that they found a stromatolite containing bacterial fossils 3.7 billion years ago in southwest Greenland.

However, there are also scientists who dispute this view. For example, stromatolites discovered by Natman et al. Have been found in "Isua green rock belt" in southern Greenland with the oldest sedimentary rock on the earth, but its interpretation is said to be very difficult. Stromatolite can also be formed chemically, as rosettes can also be formed by non-biological processes. For this reason, the question "the traces of life" found in these areas is actually left without being solved, which is actually made by a simple chemical reaction. John Valley, a geochemist at the State University of Wisconsin, says, "I do not think these other studies are wrong, but I do not think that the content is firm proof. "The rocks discovered by Mr. Natman looks like stromatolite and it is very attractive."

On the other hand, discussion has also been made as to whether water existed on the ancient earth. Mr. Valley, mentioned above, discovered zircon, suggesting that crust had existed in the Earth for 4.4 billion years ago. Zircon is a crystalline mineral containing elements such as silicon, oxygen, zirconium, etc. It is formed inside magma. Since it is a substance having a strong structure like carbon crystal, zircon can exist stably for a very long time even under high pressure and temperature environments, so that zircon is the only thing left from the Earth 's Honorable It is a valuable "time capsule" as a rock of.

ByMartin Heigan

Mr. Valley gathered some of the rocks in Jack Hills, Western Australia and carried out a detailed survey. Oxygen isotopes were discovered suggesting that crystals were formed from substances altered by liquid water. Because this zircon was one that was born 400 million years older than the oldest sedimentary rock that has been found so far, 400 million years ago the ocean It was emphasized that it existed, it was cooled and solidified. Mr. Valley thinks that such a sea would have existed around the earth, "The Horse Royalty was not a world like Hell, it is what it was understood from Zircon.The volcano is surely It was probably surrounded by the ocean, at least, there must have been some land. "

From zircon it is thought that meteors and asteroids are falling down on earth and moonLate heavy bombing periodEvidence is found as a trace of the. The Apollo project astronaut who fell to the moon from the 1960s to the 1970s brought back many stones of the moon to the earth. A detailed investigation of these stones revealed that evidence suggesting that a rapid temperature rise occurred 3.9 billion years ago was found from zircon contained in the stone. However, it should also be noted that it is premature stage to conclude that "This is evidence that there was a late heavy bombing period". In particular, since the distribution of the stone of the moon brought back by the astronaut is confined to only a part of the surface of the moon, the possibility of "just bringing back a piece of a meteorite that happened to fall there" Since it can not be done, we need to draw conclusions after further detailed investigation in the future.

As you can see from the scale of the planet, you can see the unknown form of the Earth from an unknown small stone kakera. It is also thought that the possibility of existence of life also exists on planets other than the solar system by understanding such actual situation.

Byfotomanu_93