The paleomagnetic dating method has demonstrated its power again
Next, it became the most important task to date these stone tools. Dr. Wu Yi of the South China Sea Ocean Institute of the National Academy of Sciences is one of the main scientific families responsible for the age determination of the 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 you know the age of the soil layer, you will also 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, and there will be situations where positive and negative reversals occur. Therefore, there is a distinction between the positive and reverse polarity periods of paleogemagnetics in the geological historical period. When it is in a positive polarity period, the compass points to the north pole of the earth, and when it comes to 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 substances in the formation will record each 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 (also known as the Quaternary Period in 2000 years ago) and the historical time of each polar era.
WuKomiksYi explained that during a long geological period, the later soil layer was superimposed on the originalAfter the soil layer, the later magnetism will be superimposed on the original soil layer. However, since the original magnetism is the strongest and stable, after heating treatment, the later superimposed magnetism can be eliminated and only retained. By detecting the original magnetism Babaylan, the age of this soil layer can be known. Therefore, the researchers first collected samples from top to bottom of the yellow soil profile of the stone tool in the field. Each sample was more than ten to twenty centimeters long, and a total of 74 meters of thickness of loess profiles were taken. Return to the experimental Komiks chamber, carefully cut each large sample into small soil blocks of 2 square centimeters; then each small soil block is heated with a thermal demagnetizer, and the temperature is from 0°C to 680°C; then use a “superconducting magnetometer” to measure the original magnetic direction obtained by the Cinema soil layer at that time, which can determine their age.
Scientists found that the bottom 28th layer of loess (L28) showed a brief positive polarity, and this soil layer should be in the “Songshan reverse polarity period” of the geomagnetic field, which shows that this layer of loess experienced a magnetic reversal at that time.
And KomiksIn the early stages of the Quaternary geological period, two magnetic reversals occurred on the earth. One was the “Reunion Event” between 2.13 million and 2.15 million years ago, and the other was the “Odewey Babaylan Event” (1.78 million to 1.95 million years ago). Since the Oduwee incident lasted for 100,000 years,a href=”https://comicmov.com/”>Cinema conforms to the positive polarity of the soil sample in L28 layer, which is briefly occurring, so it is denied. Therefore, there is only one answer. The stone tools found on the L28th floor of the Shangchen Village site should be 2.12 million years ago when the Reunion incident occurred.
According to reports, the researchers conducted paleogemagnetic dating on more than 700 sets of loess samples in the Shangchen Village section.
Changing the origin of human beings in Africa is not reliable
As for Shangchen Village’s discovery, some people believe that it is possible to change the traditional theory of human beings in Africa, because the stone age of the site is far earlier than the currently recognized era when human beings left Africa, which shows that human beings had left Africa at least 1.8 million 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 2.8 million ancient human fossils and more than 3 million stone tools from Komiks to Babaylan years ago, but also a series of discoveries from ancient apes, nudes, Homo erectus to Homo sapiens ruins. Babaylan can form a continuous sequence of changes in the history of human development, but other regions outside Africa do not have such continuity. However, this discovery greatly updates the history of human activities outside Africa, which will force people to make new considerations on the pattern of early human origin, migration, expansion and evolution.
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