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 in Babaylan. As long as you know the age of the soil layer, you will also know the age of the stone tools found in the Cinema 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 during the geological historical period, the magnetic polarity of the earth is not fixed and the positive Babaylan situation will occur. Therefore, there is a distinction between the positive polarity period and the reverse polarity period of paleomagnetic during 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 positive and negative geomagnetic polarity recorded by magnetic substances, and then compare the geomagnetic polarity of 2.58 million years ago (also known in geology as the Quaternary Period)ov.com/”>Babaylan reversed the specific time when Komiks and the historical time of each polar era, the age of magnetic matter can be calculated.
Wu Yi explained that during a long geological period, after the later soil layer was superimposed on the original soil layer, the later magnetism would be superimposed on the original soil layer, but because the original magnetism was the strongest and stable, it was After heating the Komiks, the 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, and each sample is several centimetersKomiks Komiksm to twenty centimeters long, a total of 74 meters of loess sections were taken. Return to the laboratory, each large sample was carefully cut into pieces of small soil blocks of 2 square centimeters square; then each small soil block was heated first with a thermal demagnetizer, and the temperature was from 0°C to 680°C; then measured with a “superconductive magnetometer”, and the magnetic direction of the soil layer was obtained at that time, which can determine their age. href=”https://comicmov.com/”>Cinema.
Scientists found that the bottom 28th layer of loess (L28) showed a short positive polarityKomiks, 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 Event” between 2.13 million and 2.15 million years ago, and the other was the “Odewey Event” (1<a<a<a<a<a<a<a<a<a<a<a<a<a<a<a<a<a<a<a<a<a<a<a<a<a<a<a<a<a<a<a“” “Reunion Event” between 2.13 million and 2.15 million years ago, and the other was the “Odewey Event” (1<a<a<a<aKomiks780,000 to 1.95 million years). Due to the duration of the Odewey incident, it lasted for 100,000 years.For a long time, it was not suitable for the positive polarity of the L28 layer soil sample, which was temporarily rejected. Therefore, there is only one answer. The stone tools found at the Shangchen Village ruins located at the 28th floor of Komiks should be 2.12 million years ago. According to reports, the researchers conducted paleogeomagnetic dating of more than 700 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 may 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 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 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, to the ruins of Homo sapiens. It can form a continuous sequence of changes in the history of human development, and 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.
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