Professor Li Siguang is an outstanding modern Chinese scientist, a famous social activist, an outstanding educator and a great patriot; he was born in 1889 in a poor family of private school teachers in Huanggang County, Hubei Province, and became an official in 1904. He spent money to study in Japan and studied shipbuilding at Osaka Technical High School. In 1907, he joined the Chinese Tongmenghui founded by Dr. Sun Yat-sen in Tokyo, and followed Mr. Sun Yat-sen to participate in the revolution that overthrew the Qing feudal dynasty. After the Revolution of 1911, he resigned as a senior government official because he was dissatisfied with Yuan Shikai and Li Yuanhong's usurpation of the fruits of the revolution. In 1913, he went abroad to study again. He studied geology under Professor Paulton at the University of Birmingham, England, and thus became associated with earth sciences and embarked on an arduous journey. And a glorious scientific path.
He returned to China in 1920 and was employed as a professor at Peking University. During his teaching period, he conducted in-depth research on the fossils of Entomidae in northern China, especially in Shanxi, in order to reveal the stratigraphic sequence and coal seam levels of the Carboniferous-Permian Taiyuan System to meet the needs of coalfield work. Later, he extended this research to South China. Because the Carboniferous and Permian limestones in South China are widely distributed and the fossils of the insect family are abundant, he collected a large number of fossil specimens of the insect family and studied their shell structures in detail, thereby establishing The classification standard for the fossils of the family Entomidae was established. This standard has been widely accepted and adopted; he has written extensively on the study of insecticides, and his book "Insectidae in Northern China" (published in 1921) laid the foundation for the classification, evolution, distribution and application of insecticides fossils. , which solved the stratigraphic problems of the long-undivided Carboniferous-Permian Taiyuan System in North China and the Carboniferous and Permian limestones widely distributed in South China. In terms of stratigraphy, he and Zhao Yazeng first measured and studied the stratigraphic profile of the Three Gorges of the Yangtze River in detail in 1924. This standard profile was later widely used and used to compare it with the Early Paleozoic-Late Precambrian in other areas, especially in South China. age stratigraphy for comparison.
In 1921, when he led students for field practice, he first discovered China's Quaternary glaciers at the eastern foothills of the Taihang Mountains. Since then, he has carried out further investigations and collected records in the middle and lower reaches of the Yangtze River, Mount Lushan in Jiangxi, Huangshan in Anhui and other places in South China. After seeing more evidence of the prevalence of glaciers, he published a series of articles on China's Quaternary glaciers, among which "Lushan in the Ice Age" is one of his masterpieces. After identification based on a large amount of data he investigated, he determined three glacial periods and two interglacial periods in Poyang, Daku and Lushan, and later proposed that there was an older sub-glacial period before the Poyang glacial period. The establishment of Quaternary glaciers in China is an important milestone in the study of Quaternary stratigraphy and climatology in my country. In production practice, it is not only beneficial but also effective in searching for groundwater resources, placer gold deposits and selecting engineering construction sites.
When he was working on the Carboniferous-Permian strata of East China, he found that the north of these strata was mainly continental clastic sediments, interspersed with marine limestone, while the south was mainly marine gray. rock. This indicates that the water deepens from north to south. After his preliminary exploration of the advance and retreat rules of the sea water on the continent, he came to a hypothesis: the advance and retreat of the sea water on the continent may be directional movement from the equator to the poles and from the poles to the equator. This change in directional motion may be caused by the rapid and sometimes slow changes in the Earth's rotation speed over the long geological era. Therefore, he proposed that the rocks that make up the continent will undergo rigid and plastic deformation under the long-term in-situ stress. Based on many years of field work experience, he discovered that all deformation (tectonic) phenomena existing on the earth's surface, their orientations, relative to the earth's rotation axis, are Regularly. He pointed out: All structural traces that are causally related are often combined in a certain form to form a special system, that is, a structural system. He divided the tectonic system into three types: first, the zonal tectonic system; there are three east-west structural belts in China, namely the Tianshan-Yinshan east-west structural belt, the Kunlun Mountain-Qinling east-west structural belt and the Nanling east-west structural belt. tectonic zone. Second, the meridional structural belt; third, various twisting structures, including mountain-shaped structures, multi-shaped structures, in-shaped structures, checkerboard structures and twisting structures, among which the larger-scale twisting structural systems It is the NNE-NE-trending Neocathaysian system in eastern China, as well as various convolution structures.
He also established the working methods and procedures of geomechanics. He proposed that the response of rocks to stress mainly determines the mechanical properties of rocks, the length of time of stress and the physical conditions of the rocks, especially the thermal state of the location. Li Siguang's thoughts on crustal structure and crustal movement have been published systematically in "Chinese Geology", "Basics and Methods of Geological Mechanics", "Introduction to Geological Mechanics" and other works. For such a marginal subject, he felt that it was useful to The term "geomechanics" is more precise.
In 1927, at the invitation of Cai Yuanpei, President of the Academia Sinica, Li Siguang presided over the establishment of the Institute of Geology and became the first director, serving for more than 20 years. During the flames of the Anti-Japanese War, he led all the staff of the institute and traveled thousands of kilometers to persist in the research of geological science and paleontology. He worked tirelessly and devotedly to the development of China's geological sciences and trained a large number of talents. He engaged in scientific research without relying on foreigners or superstitious authority. He did in-depth research in the fields of Quaternary glaciers, micropaleontology, geomechanics, etc. Outstanding scientific results have been achieved.
Li Siguang has long served as professor and director of the Department of Geology at Peking University, and has cultivated a number of famous geologists. He also serves as a member of the Peking University Senate, a member of the Appointment, Finance, General Affairs Committee and a member of the Instrument Committee. Long grade. Assisted President Cai Yuanpei and made contributions to the construction of Peking University’s academic affairs. In addition, he also organized the establishment of Wuhan University, served as acting president and professor of the Central University, and deputy director of the Beijing Library.
On the eve of the founding of New China, although Li Siguang was far away in Europe giving lectures and inspections, he was still concerned about the fate of his motherland. In early 1949, he wrote several times to Xu Jie of the Institute of Geology of Academia Sinica (a geologist, former deputy minister of the Ministry of Geology after liberation, and an academician of the Chinese Academy of Sciences) and others, supporting them to stick to Nanjing and oppose the relocation of Guangzhou, in order to support the new China. The geological sciences enterprise retains a team and equipment. He himself refused the inducements of the Kuomintang government, broke through numerous obstacles, returned to the embrace of the motherland in early 1950, and devoted himself to the construction of New China ever since.