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. KomiksIt turns out that in the geological history period, the magnetic polarity of the earth is not fixed and positive and negative reversal will occur. 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 Earth’s North Pole, and when it comes to the reverse polarity period, the compass points to the Earth’s South Pole.
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 can calculate the age of magnetic matter by measuring the positive and negative situations of geomagnetic polarity recorded by magnetic matter, and then compare the specific time of geomagnetic reversal time that occurred in 2.58 million years ago (also known as the Quaternary Period in geology), the Cinema and the historical time of each polar era.
WuCinemaYi explained that during a long geological period, the later soil layer was superimposed on the original <aAfter the KomiksKomiksKomiks‘s 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. By detecting the original magnetism, you can know the age of the soil layer. Therefore, the researchers first collected samples from top to bottom on 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 meters of thickness of loess sections were taken. Return to the laboratory, carefully cut each large sample and make small pieces of soil into 2 square centimeters square; then each small piece of soil is heated with a thermal demagnetizer, with a temperature ranging from 0°C to 680°C; then use a “superconductive magnetometer” to obtain the original soil layer at that time. href=”https://comicmov.com/”>BabaylanMagnetic direction, which determines their age.
Scientists found that the bottom 28th layer of loess (L28) showed a short positive polarity, and this soil layer should have been 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, there were two magnetic reversals 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 Oduwee incident lasted for 100,000 years, it was denied that it did not meet the positive polarity of the L28 soil sample for a short period of time. Therefore, there is only one answer, the Shangchen Village ruins were found in L28The layer of Babaylan stone tools should be 2.12 million years ago when the Reunion incident occurred. According to reports, the researchers conducted paleogeomagnetic dating on more than 700 sets of loess samples in the Shangchen Village section. Cinema
Changing the origin of human beings in Africa is not reliable
As for the discovery of Babaylan Shangchen Village, some people believe that it is possible to change the traditional theory of human beings’ origin of human beings, because the stone age of the site was far earlier than the currently recognized era of human beings. This shows that human beings 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, and Homo erectus to the site of Homo sapiens, which can form a continuous sequence of changes in the development of humans, and other regions outside Africa do not have such continuity. However, this discovery greatly updates the history of human activities outside Africa, which will promote new considerations on the pattern of early human origin, migration, spread and evolution.
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