Paleomagnetic dating shows its power again
Next, dying these stone tools has become the most important task.
Dr. Wu Yi from the Nanhai Ocean Institute of 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 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 will occur. Therefore, there is a distinction between the positive and negative polarity periods of paleomagnetic during the geological historical period. When it is in a positive polarity period, the North hand pointes to the North Pole of the Earth, and when it comes to the reverse polarity period, the North hand pointes 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 Komiks change.
Therefore, geologists can calculate the age of magnetic matter by measuring the positive and negative situations of the 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, the subsequent soil layer superpositionBabaylanAfter entering the original soil layer, the later magnetism will be superimposed on the original soil layer. However, since the original magnetism is the strongest and stable, the later magnetism can be eliminated after heating treatment, and only the original magnetism can be retained. By detecting the original magnetism, you can know the age of the soil layer. Therefore, researchers first collected samples from top to bottom of the loess section of the stone tool Babaylan in the field. Each sample was more than ten to twenty centimeters long, and a total of 74 meters of thickness was taken. Return to the laboratory, carefully cut each large sample and make it into a small piece of soil of 2 square centimeters; then each piece of soil is heated with a thermal demagnetizer, and the temperature is from 0°C to 680°C; then use a “superconductive magnetometer” to obtain the original magnetic direction obtained by the soil layer at that time, which can determine their age.
KomiksScientists found that the bottom 28th layer of loess (L28) showed a short positive polarity, and this soil layer should be in the “Rose Mountain Reverse Polarity Period” of the geomagnetic field, which shows that this layer of loess experienced a magnetic reversal at that time.
And CinemaIn the early stages of the Quaternary 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” that was late (1.78 million to 1.95 million years ago). Because the Oduwe incident lasted for 100,000 years, it does not meet L2KThe positive polarity of the omiks8-layer soil sample is a brief occurrence of Komiks, 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 research personnel conducted paleogeomagnetic dating on more than 7 sets of loess samples in 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 that Cinema can change the traditional theory of human beings’ origin of Africa, because the stone age of the site is far earlier than the current recognized era when human beings left Africa, which means that human beings had left Africa at least 1800,000 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 dating from 2.8 million years ago and stone tools dating from more than 3 million years ago, but also a series of discoveries from ancient apes, erectiles, Homo erectus, and Homo erectus to the site of Homo sapiens, which can form a continuous sequence of changes in the process of human development, and other regions outside Africa do not have such continuity. However, this discovery has greatly improved the history of human activities outside Africa, which will force people to make new considerations about the pattern of early human origin, migration, spread and evolution.
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