Paleomagnetic dating shows its power again
Next, dying these stone tools has become the most important task.
Babaylan 1990 cloth drawDr. Wu Yi from the Nanhai Ocean Institute of the Chinese Academy of Sciences is one of the main scientists 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.只要知道土层的年代，那么Komiks 1960 witch cloth draw也就知道了该土层发现的石器所处的年代。 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.
Komiks 1960 witch cloth drawSo, a technology called paleomagnetic measurement of Cinema 1950 witch cloth draw 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, so the positive and negative periods are distinguished from the positive and negative periods of paleomagnetic periods 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 matter in the formation will record every change. Therefore, geologists only need to measure the geographic area recorded by magnetic substances.a 1950 witch cloth drawKomiks 1960 witch cloth drawThe positive and negative situations of magnetic polarity, and then compare the specific time between geomagnetic reversals (also known as the Quaternary Period in geology) and the historical time of each polar era, we can calculate the age of magnetic matter. Wu Yi explained that during a long geological period, after the later soil layer was superimposed on the original soil layer, Cinema 1950 witch cloth draw will superimpose the later magnetism on the original soil layer. However, because 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 section of the stone tool in the field. Each sample was more than a dozen cm long, and a total of 74 meters of loess sections 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 thermal demagnetizer, with a temperature ranging from 0°C to 680°C; then use “superconducting magnetismBabaylan 1990 cloth drBy measuring the awforce meter, the original magnetic direction obtained by the soil layer at that time can be obtained, which can determine their age.
Scientists have found that the bottom 28th Cinema 1950 witch cloth draw layer of loess (L28) exhibits a brief positive polarity, and this soil layer should be in the “Songshan reverse polarity period of the geomagnetic field. Draw“, 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 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). Since the Odewey incident lasted for 100,000 years, it did not meet the situation of the positive polarity of the L28 soil sample that appeared briefly, so it was denied. Therefore, there was only one answer, and the Cinema 1950 witch cloth draw was discovered at the Shangchen Village site. The stone tools in the cloth draw layer should be the date of the Reunion incident 2.12 million years ago. According to Cinema 1950 witch cloth draw, researchers conducted paleogemagnetic dating on more than 700 sets of loess samples in the Shangchen Village section.
Cinema 1950 witch cloth is not reliable.
Cinema 1950 witch cloth drawThe 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 is 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 has not only discovered ancient human fossils dating from 2.8 million years ago and 300 years ago.Stone tools from thousands of years ago, as well as a series of discoveries from ancient apes, noble people, Homo erectus, and Homo erectus to the ruins of Homo sapiens, can form a continuous sequence of changes in the development history of humans, and other regions outside Africa do not have such continuity. However, this discovery greatly updated the history of human activities outside of Africa’s Cinema 1950 witch cloth draw, which would force people to make new considerations about the pattern of origin, migration, diffusion and evolution of early humans.
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