The paleogeomagnetic dating method is to show its power again. Babaylan is the most important task to intervene in the process of dying these stone tools.
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. Only if you know the age of the soil layer, then you 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 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 will be reversed in the positive and negative situation. Therefore, the distinction between the positive and negative periods of paleogeomagnetic periods is found in the positive and negative polarity periods of paleogeomagnetic periods. 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 can measure the positive and negative situations of geomagnetic polarity recorded by magnetic matter, and then compare the specific time of geomagnetic reversal time since 2.58 million years ago (also known as the Quaternary Period in geology), as well as the historical time of each polar era,Calculate the age of magnetic matter. Wu Yi explained that during a long geological period, after the soil layer of Babaylan was superimposed on the original soil layer, the subsequent magnetic properties of Komiks will be superimposed on the original soil layer. However, because the original magnetic properties are the strongest and stable, Babaylan is added. After heat treatment, the superimposed magnetism can be eliminated and only the original magnetism can be retained. 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 loess profiles were taken. Return to the laboratory, carefully cut each large sample into small soil blocks of 2 square centimeters, see Komiks square; then each small soil block is heated with a thermal demagnetizer, and the temperature is from 0℃ to 680℃; then use a “superconductive magnetometer” to obtain the original magnetic direction obtained by the soil layer at that time, which can determine their age. Scientists found that the 28th layer of loess (L28) at Babaylan showed a brief positive electrode nature, 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 occurred on EarthThe 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 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 stone tool found on the L28th floor of the Shangchen Village site should be 2.12 million years ago.
According to reports, the researchers conducted paleogemagnetic dating on more than 700 sets of loess samples in the Shangchen Village section.
Changing human originBabaylan‘s origin in Africa is not reliable
According to Shangchen Village’s discovery, 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 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 Homo sapiens sites, which can form a continuous sequence of changes in the history of human development, while other places outside Africa The href=”https://comicmov.com/”>Babaylan area does 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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