In China, the observation and study of caves are recorded in writing, which can be traced back to the pre-Qin period (22 BC1year). 1995 [7] After consulting a large number of ancient books, the research situation before Ming and Qing Dynasties was summarized:
(1) Pre-Qin to Song and Yuan Dynasties
(1) Pre-Qin period (22 BC1year): It is mainly a superficial understanding of the cave location and observation records of rocks and hydrological phenomena. (2) During the Han and Three Kingdoms Period (206 BC-265 AD), we mainly explored caves and learned about chemical deposits in caves. Named according to their shapes, such as stalactites, stone flowers, stone beds, stone brains, stone pillars, etc. (3) Jin Southern and Northern Dynasties (AD 260-594): During this period, the field and research content of cave investigation have been expanded and deepened unprecedentedly, which can be said to be the first high step in the milestone of the development of ancient cave science in China. It is shown as follows: (1) The cave investigation area is expanded (to the south of the Yangtze River); The names and genetic descriptions of various chemical deposits in caves are given. The initial load of cave microclimate; The increase of cave hydrology knowledge; Records of cave creatures; Cave utilization and so on. ④ Sui and Tang Dynasties (589-896 AD): The Sui and Tang Dynasties can be said to be the second high step in the development of ancient cave science in China. At this time, the first national cave annals in China, Beitang Shuchao, came out, which not only regarded cave science as an independent discipline, but also deeply analyzed the causes of chemical deposition in some caves. ⑤ Song and Yuan Dynasties (AD 960- 1368): During this period, the second cave monograph "Gui Hai Dong Yanzhi" came out in China, which is another cave monograph after "Cave in Heaven and Blessed Land" and is much more detailed than the latter. During this period, the research area expanded to the southwest area where karst is most developed in China, especially the caves in Guangxi, and was investigated more extensively and deeply. In addition, during the period from Renzong to Zhezong in the Northern Song Dynasty (A.D.1031-KLOC-0/095), Dr. Joseph Needham, a British historian of science, called Shen Kuo "the most peculiar figure in the history of science in China" and called his Notes on Meng Xi a milestone in the history of science in China [8]. Shen Kuo said in Volume 25 of Meng Qian's Bi Tan: "There is a bitter spring flow in Qianshan County, Xinzhou ... and stalactites are dripping in the cave, while in the Spring and Autumn period, Jing Quan gave birth to stone flowers, and yin essence stones were born under the big brine, all of which were wet." [9] Here Shen Kuo describes his views on the origin of cave sediments.
(2) Ming and Qing Dynasties
Xu Hongzu, the most representative figure in cave exploration and research in Ming and Qing Dynasties, is the first, and his masterpiece is Xu Xiake's Travels. [7] said: "Travel Notes" is a wide-ranging geographical masterpiece, involving many aspects of natural geography and human geography. Among them, the research on karst landforms and caves, hydrogeology and phytogeography climbed to the peak of the world at that time. Its investigation and research projects on caves include: cave location, cave rocks, cave scale, cave chemical deposition, cave genesis, cave climate, cave hydrology, cave biology, cave light, cave sound, cave cultural relics, cave classification, cave place names, cave utilization and so on. There are many records in the travel notes, which cover almost all the contents of modern research on caves.
[Ming] Xu Hongzu mentioned in the description of the origin of cave sediments: "Jade and milk are all in harmony" or "stone slurry is condensed" [10]. It is mentioned that travertine in caves is the chemical precipitation produced by "jade milk" and "stone slurry"-the solution is melted or solidified-evaporated.
2. Modern research
Modern research mainly refers to 1949 karst cave research since the founding of the People's Republic of China. During the Republic of China, only sporadic work was done for a long time, and no obvious progress was made.
(1) Research before the reform and opening up
During the period from the founding of People's Republic of China (PRC) (1949) to the reform and opening up (1978), due to the needs of national large-scale economic construction, karst research has been greatly developed. In the past 30 years, people have done a lot of investigation, exploration and research on karst caves, and accumulated extremely rich information and research results. The national research conference held in 196 1 year pointed out the future research direction on the basis of summarizing the previous work. 1966 held a national karst academic conference to discuss the basic problems and research direction of karst science (author's note: this meeting decided to change the word "karst" to "karst"). 1975, the National Ten-year Karst Planning Conference was held, and the Institute of Karst Geology of the Ministry of Geology and Mineral Resources was established in Guilin, Guangxi. The main work during this period is karst hydrogeology, karst engineering geology, karst landform and karst development history. Regionally, the research of important water conservancy projects is the most detailed, and the karst research in Guizhou and Guangxi has achieved unprecedented development at this time [3].
(2) Research after the reform and opening up.
During this period, in addition to the research on karst hydrogeology, karst engineering geology, cave investigation and cave utilization, which are closely related to national economic construction. The theoretical research on the origin of karst caves has also developed rapidly. Cave exploration, cave discovery and cave tourism have also developed rapidly with the start of market economy. During this period, China also studied "biological karst".
It is worth mentioning that since the 1980s. In some karst research in China, professionals of basic geology join forces to participate in karst research. In the process of cooperation, they put forward some new views on karst research.