The paleomagnetic dating method has shown its power again
Next, dying these stone tools has become the most important task. Dr. Wu Yi from the South China Sea Institute of Babaylan, 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 yellow land strata samples where the stone tools are located. As long as you know the age of the soil layer, then Komiks 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 millions of 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 a situation of positive and negative reversal. Therefore, there is a distinction between the positive and negative polarity periods of paleogemagnetics in 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 substance in the Babaylan layer will record every change in Komiks. Therefore, geologists only need to measure the positive and negative situations of geomagnetic polarity recorded by magnetic substances, and then compare the specific time when the geomagnetic reversal time occurred in 2.58 million years ago (also known in geology as the fourth Babaylan period), as well as the specific time of the occurrence of geomagnetic reversal time, as well as theThe age of magnetic matter can be calculated by the historical time of various polar eras. Wu Yi explained that during the long geological period of Babaylan, the later soil layer was added to the original soil layer, and the later magnetism would be superimposed on the original soil layer. However, since the original magnetism was the strongest and stable, the later magnetism could be eliminated after heating treatment, and only the href=”https://comicmov.com/”>Cinema retains its original magnetism, and by detecting the original magnetism, the age of this soil layer can be known.
Therefore, the researchers first collected samples from top to bottom of the loess section of the stone tool in the field. Each sample was more than ten to twenty centimeters long, and a total of 74-meter-thick loess sections were taken. Return to the Komiks laboratory, each large sample was carefully cut and made into small pieces of soil of 2 square centimeters square; Komiks After Babaylan, each small piece of soil is heated by a thermal demagnetizer first, and the temperature is from 0°C to 680°C; then the Cinema is measured with a “superconducting magnetometer” to obtain the original magnetic direction obtained by the soil layer at that time, which can determine their age.
CinemaScientists found that the bottom is The 28th layer of loess (L28) under Komiks showed a short positive polarity, and this soil layer should have been in the “Spine Mountain 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 Quaternary Geological Period, two occurred on the earth.The second magnetic reversal time is, one is the “Reunion incident” between 2.13 million and 2.15 million years ago, and the other is the “Odewey incident” between 1.78 million and 1.95 million years ago. Since the Oduwee incident lasted for 100,000 years, it did not meet the L28-layer soil sample and was temporarily 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. Cinema
According to reports, researchers conducted paleogeomagnetic 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
According to Shangchen Village’s discovery, some people believe that it is possible to change the traditional theory of human beings’ origin of Africa, because the stone age of the site was far earlier than the time when humans walked out of Africa, which means that humans 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 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 history of human development. Other regions outside Africa do not have such continuity. However, the discovery greatly renews 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.
1 2