Paleomagnetic dating shows its power again
Next, the generation of these stone tools became Komiks for the most important work.
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 does not directly measure stone tools, but 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 this soil layer. However, many commonly used dating methods, such as radioisotope dating, photoluminescence dating, etc., either cannot measure soil samples a million years ago, but are not suitable for dust deposits like 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 the positive and negative reversal will occur. Therefore, there is a distinction between the positive and negative periods of paleomagnetic magnetic positive and negative periods in the geological historical period. When it is in the positive polarity period, the compass will point to the north pole of the earth, and when it comes to the reverse polarity period, the compass will point to the south pole of the earth.
This kind of geomagnetic reversal will be on the long history of the earthIn history, it continues to occur, so the magnetic substance in the Cinema layer 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 when the geomagnetic reversal time occurred in 2.58 million years ago (also known as the Quaternary Period in geology) and the historical time of each polar era. Wu Yi explained that after the later soil layer was superimposed on the original soil layer during a long geological period, the later magnetism would be superimposed on the original soil layer. However, since the original magnetism was the strongest and stable, after heating treatment, the later magnetism could 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 ten centimeters to twenty centimeters long, and a total of 74 meters of thickness of loess sections were taken. Komiks Return to the laboratory, carefully cut each large sample and make it into small pieces of soil 2 square centimeters square; then each piece of soil is heated first with a thermal demagnetizer, and the temperature is from 0°C to 680°C; then use a “superconductive magnetometer” to measure the original magnetic direction obtained by the 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 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, 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 “latest “The Babaylan incident (1.78 million to 1.95 million years ago). Since the Oduwe incident lasted for 100,000 years, it was denied that it did not meet the positive polarity of the soil sample in the L28 layer, and it was denied. In Komiks, there was only one answer. The stone tool found on the L28 floor at the Shangchen Village site should be the date of the Reunion incident 2.12 million years ago. href=”https://comicmov.com/”>Cinema. According to reports, researchers conducted paleogemagnetic dating on more than 700 sets of loess samples in Shangchen Village.
Changing human origin in Africa is not reliable
As for Shangchen Village’s discovery, some people believe that it may change the traditional theory of human origin in Africa, because of the stone years of the site. href=”https://comicmov.com/”>Cinema The era 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 stated 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 stone tools dating from more than 3 million years ago, but also a series of discoveries from ancient apes, erotic people, Homo erectus, and Homo erectus to Homo sapiens site, which can form a continuous sequence of changes in the history of human development, and other regions 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 a pattern of the origin, migration, diffusion and evolution of early humans. href=”https://comicmov.com/”>Babaylan makes new considerations.
1 2