Paleomagnetic dating has shown its power againBabaylan
Next, dying these stone tools has become the most important task. Dr. Wu Yi from the Institute of South China Sea Ocean Research, Chinese Academy of Sciences is one of the main scientists responsible for the age determination of loess strata in this study. Wu Yi introduced that the method of dying stone tools is not to directly measure the stone tools, but to measure the age of the loess strata samples where the stone tools are located. As long as Babaylan knows the age of the soil layer, then you will know the age of the stone tools found in the soil layer. However, many commonly used dating methods, such as radioisotope dating, photoluminescence dating, etc., either cannot measure soil samples a million years ago, or are not suitable for dust deposits such as loess.
So, a technology called paleomagnetic dating is here to show its power. It turns out that in the geological historical period, the magnetic polarity of the earth is not fixed and reversed, because Komiks, there is a distinction between the positive and reverse polarity periods of paleomagnetic during the geological historical period. When it is in the positive polarity period, the compass points to the north pole of the earth, and when it is in the reverse polarity period, the compass points to the south pole of the earth.
This kind of geomagnetic reversal will continue to occur throughout the long history of the earth, so the magnetic matter in the formation will record every change.
Therefore, geologists can calculate the age of magnetic matter by measuring the positive and negative situations of geomagnetic polarity recorded by magnetic matter, and then compare the specific time of geomagnetic reversal time since 2.58 million years ago (also known as the Quaternary Period in geology) and the historical time of each polar era. Wu Yi explained that during a long geological period, after the soil layer from Komiks was superimposed on the original soil layer, the later magnetism would be superimposed on the original soil layer, but because the original Cinema had the strongest magnetism and stable, so after heating treatment, the later superimposed magnetism can be eliminated and only the original magnetism can be retained. By detecting the original magnetism, the age of this soil layer can be known.
Because of this, the researchers first collected samples from top to bottom of the loess profile of the stone tool in the field. Each sample was more than ten centimeters to twenty centimeters long, and a total of 74 meters of loess profiles were taken. Return to the laboratory, carefully cut each large sample into small soil blocks of 2 square centimeters; then use a thermal demagnetizer to heat each small soil block with a temperature ranging from 0°C to 680°C; then use a “Cinema to measure it with a “Cinema superconducting magnetometer” to obtain the original magnetic direction obtained by the soil layer at that time, which can determine their age.
Scientists found that the bottom 28th layer of loess (L28) showed a short positive polarity, and this soil layer should have been in the “Songshan reverse polarity period” of the geomagnetic field, which shows that this layer of loess experienced a magnetic reversal at that time. In the early stages of the fourth geological period, two magnetic reversals occurred on the earth. One was the “Reunion incident” between 2.13 million and 2.15 million years ago, and the other was the “Odewey incident” (1.78 million to 1.95 million years ago). CinemaBecause the Oduwee incident lasted for 100,000 years, it did not meet the positive polarity of the L28 soil sample, which was briefly encountered, so it was denied. Therefore, there is only one answer. The stone tool found on the L28th floor of the Shangchen Village site should be 2.12 million years ago.
According to reports, the researchers conducted paleogemagnetic dating on more than 700 sets of loess samples in the Shangchen Village section.
Carrying the origin of human beings in Africa is not reliable
About Shangchen Village’s discovery, some people believe that it is possible to change people CinemaThe traditional theory of origin in Africa, because the stone age of the site was far earlier than the time when humans left Africa recognized by Cinema, which shows that humans had left Africa at least 180 thousand years ago. In this regard, Zhu Zhaoyu said that the current discovery in Shangchen Village is not enough to change the theory of human beings leaving Africa, because Africa has not only discovered ancient human fossils 2.8 million years ago and stones more than 3 million years ago, but also from ancient apes, erect, Homo erectus, to the ruins of Homo sapiens A series of discoveries can form a continuous sequence of changes in the course of human development, and other regions outside Africa do not have such continuity as Komiks. However, this discovery greatly updates the history of human activities outside Africa, which will prompt people to consider the early pattern of human origin, migration, spread and evolution.
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