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 stratigraphic 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, Cinema light luminescence dating, etc., either cannot measure the soil samples from 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 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 the positive pole period, the compass points to the north pole of the earth, and when it comes to the reverse polarity period, the pointing point to the south pole of the earth. Cinema
This kind of geomagnetic reversal will continue to occur throughout the long history of the earth, so the magnetic matter in the geological layer will record every change. Therefore, geological workers only need to measure the positive and negative situations of geomagnetic polarity recorded by magnetic substances, and then compare the date 2.58 million years agoFrom the specific time when the geomagnetic reversal time occurs (also known as the Quaternary Period in geology), as well as the historical time of the Komiks era, we can calculate the age of magnetic matter.
Wu Yi explained that during a long geological period, after the later soil layer is superimposed on 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, after heating treatment, the later superimposed magnetism can be eliminated and only retained the original magnetism. 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 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 laboratory, carefully cut each large sample into small soil blocks of 2 square centimeters; then each small soil block is heated first with a thermally retardant magnetometer, with a temperature ranging from 0℃ to 68Komiks0℃; then use a “superconducting magnetometer” to obtain 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 short 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.
In the early stages of the Quaternary geological period, two magnetic reversals occurred on the earth. One was the “Reunion EventBabaylan” that dated 2.13 million to 215 years ago, and the other was the “Babaylan” that was late.The Oduwe incident (dating 1.78 million years ago to 1.95 million years ago). Since the Oduwe incident lasted for 100,000 years, it did not meet the positive polarity of the L28 soil sample in the L28 layer, so it was denied. Therefore, there was only one answer. The stone tool found on the L28 layer at the Shangchen Village site should be around 2.12 million years ago. According to reports, researchers conducted paleogemagnetic dating on more than 700 sets of loess samples in the Shangchen Village section. The African theory is not reliable to change the origin of human beings. href=”https://comicmov.com/”>Babaylan
For the discovery of Shangchen Village, some people believe that it may change the traditional theory of human origin in 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 humans leaving Africa, because Africa is not currently <a Komiks only discovered ancient human fossils dating from 2.8 million years ago and stone tools dating from more than 3 million years ago. A series of discoveries from ancient apes, nudes, Homo erectus, and Homo erectus to the site of Homo sapiens can form a continuous sequence of changes in the history of human development. Other areas 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 about the pattern of early human origin, migration, diffusion and evolution.
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