Ape Cave and Shihua Cave in Zhoukoudian, Beijing
1. Peking Man Site-Peking Zhoukoudian Man Cave
Beijing ape-man site is located on the north slope of Gulong in the west of Zhoukoudian, Fangshan District, 60 kilometers southwest of Beijing. From 65438 to 0987, UNESCO listed Zhoukoudian "Peking Man" site as a cultural heritage in the World Heritage List.
Geologically, Longgushan is located in the southwest wing of Beiling syncline in Xishan, Beijing, on the secondary anticline formed by limestone of Shangjiagou Formation in Upper Middle Ordovician. Majiagou limestone is pure, mixed with soluble gypsum and salt breccia limestone, which is a good soluble rock to form karst caves. There are no large faults in this area, only some small faults and 6 groups of shear fault structures are seen. The karst types developed here mainly include karst caves, shafts, funnels and fractures. Most caves have been filled with various types of sediments. Within less than 1km2 of Gulong Mountain, there are five caves inhabited by ancient humans, namely, the Ape Cave, the Fourth Site, the 15th Site, the Dingdong Cave and the Xindong Cave, leaving behind precious and rich ancient human fossils and cultural relics. At the same time, a large number of paleontological fossils, paleoclimate and paleoenvironment change information were also found in the cave.
Peking Man Cave is the largest karst cave in this area (Figure 3-29). The highest is at the top of the southern fissure, with an altitude of 128m, and the lowest is in the exploratory well at the bottom of the cave, with an altitude of about 80m, which is lower than the modern Zhoukoudian river surface. The sediments in the cave are mainly limestone debris with sand layer and calcium plate, including several layers of ash layer and burnt soil, which are divided into 17 layers (Figure 3-30). Since the first human tooth fossil was found in the cave of the ape-man in 192 1, a large number of ancient human fossils and other remains have been found in the cave sediments. Especially in1929 65438+February, Professor Pei Wenzhong discovered the first complete skull of "Beijinger" and renamed it Zhong Zhen Foreign. A large number of mammalian fossils, accounting for about 96 species, have also been found in caves, many of which have become extinct. There are 62 species of bird fossils. In addition, reptile fossils, plant fossils and a large number of spore pollen were also found. Zhoukoudian ape-man cave deposit is the standard bed of Quaternary Middle Pleistocene in northern China. According to dating, "Beijingers" lived about 600,000 to 200,000 years ago.
Figure 3-29 Beijing Ape Cave
Figure 3-30 Schematic Diagram of the Western Wall Section and Exploration Well of the First Site in Zhoukoudian, Beijing (Qian Fang Schematic Diagram)
A lot of detailed and diverse research work has been done on the Peking man site and its surrounding areas, and the Peking man exhibition hall has been established. Experts and scholars have published dozens of monographs, hundreds of papers and a large number of popular science articles, which are of great significance in anthropology, archaeology, paleontology, Quaternary geology, ecological environment, global change and other disciplines, especially the discovery of stone tools and fire, which established the process and viewpoint of human evolution from apes. The discovery of Zhoukoudian ape-man skull is the greatest discovery of anthropology in the 20th century. The loss of the ape-man skull in Zhoukoudian, War of Resistance against Japanese Aggression, is also the most mysterious mystery in the 20th century.
2. Shihuadong
Shihuadong is located in Mi Ying Village, Hebei Town, Fangshan District, southwest of Beijing, about 50km away from the center of Beijing and about 10km away from Zhoukoudian (Figure 3-3 1). Shihuadong is also developed in the limestone of Majiagou Formation of Ordovician in the north wing of Beiling syncline. Because the Ordovician limestone is thick, pure and brittle, and the structural cracks and tensile joints are developed, the underground karst caves in this layer are very developed. Shihua Cave was discovered by Master Yuan Guang in the Ming Dynasty when he visited the Western Hills of Beijing on 1446. It was named "Hidden Cave". 198 1 year, the hydrogeological team of Beijing Geological Bureau conducted a karst geological survey in this cave, and found that the cave has 6 floors (the 7th floor was later found), and there are a lot of colorful stone flowers in the cave, so it was renamed Shihua Cave. Shihua Cave is the most famous cave in China and one of the largest caves in northern China. 200 1, Shihua Cave was named as National Geopark by the Ministry of Land and Resources. In 2006, it was jointly declared as Fangshan World Geopark with Zhoukoudian Peking Man Site, Du Shi and Yeshanpo.
Figure 3-3 1 Regional Location Map of Shihuadong National Geopark at Peking Ape Site (according to Dong Demao et al., 2004)
Shihuadong is well-known at home and abroad for its unique karst cave deposition type and morphological diversity, typicality, naturalness, integrity and rarity. Academician Lu Yaoru, a karst expert in China, once appreciated the inscription "Shihua is famous in the world, and the wonders of the world are in Shihua"; Mr. Eide, director of the Geological Department of UNESCO, was amazed after visiting Shihua Cave, leaving an inscription "Everything is for the best development"; Mr. D.C. Ford, chairman of the International Cave Association and a professor at Max University in Canada, said after the visit that Shihua Cave is a "cave with excellent erosion patterns and chemical deposits". Many geologists and experts who study karst at home and abroad feel as if they have entered a dazzling cave hall when they walk into Shihuadong World Geopark. It concentrates almost all types and forms of chemical deposits in karst caves, which makes people too busy to watch and linger. * * * issued the praise of "China's karst in various forms, and Kyoto stone flowers are wonderful flowers". Mr. Zhao Xun, a judge of the World Geopark, called Shihua Cave "a geological wonder in the west of Beijing" and highly summarized the karst landscape of Shihua Cave.
(1) Shihuadong karst cave system
Shihua Cave is a multi-layer karst cave system with obvious natural layers (Figure 3-32). It is divided into seven floors from top to bottom, of which the upper five floors are above the water surface and have been partially opened to tourists. The elevation from top to bottom are 25 1m, 204m, 173m, 146m, 136m, and 1 ~ 5-storey tunnel has a total length of about 5000m. The 6th and 7th floors are underground rivers and water-filled tunnels. The underground rivers flow out of the surface in nearby Wanfo Hall. There are funnels, slopes and cliffs between the layers of the cave. There are 28 caves and caves in the open 1, 2 and 3 floors, and there are 63 branch caves and caves of different sizes. Vortex holes are usually located at the top of caves (Figure 3-33). In these caves, various types and strange shapes of carbonate sediments are deposited. The grand hall, winding corridors and dazzling walls in the cave are of great aesthetic and scientific value.
Figure 3-32 Schematic Diagram of Cave Strata in Shihua Cave (According to Dong Demao et al. )
(2) Chemical deposition in karst caves
According to Dong Demao and others' research, there are five types of chemical deposits in the cave: dripping water, seepage water, flowing water, stagnant water and splashing water, and there are more than 40 deposition forms, especially a piece of moon milk stone was found in the cave for the first time (Figure 3-34). There is the largest and thinnest stone shield known in China at present; The largest number of stone shields (Figure 3-35) (more than 600) and rare two-color stone shields; There is a large and thin stone flag (up to1.8m); There are also typical sedimentary types such as giant stalactites with a height of 10m and a width of 8m (Figure 3-36).
1) drip deposition type: the aqueous solution rich in calcium carbonate permeates vertically along the cracks in the upper part of the cave and is deposited on stalactites, stalagmites and connected stone pillars (Figure 3-37), stone curtains and stone pipes (Figure 3-38) at the top or bottom of the cave.
2) Percolation sedimentation type: the aqueous solution rich in calcium carbonate slowly seeps out along the cracks in all directions near the cave, and grows outward to form sediments such as stone flags, stone shields, stone branches and stone grapes (Figure 3-39).
3) Flowing water deposition type: The flowing water containing calcium carbonate flows slowly along the crack channel or the floor of the cave for a long time, so that calcium carbonate is continuously deposited over time, forming deposition forms such as stone waterfalls (Figure 3-40), wall-flow stones, stone steps, edge stone dams, calcium slabs and stone shells.
Figure 3-33 Vortex Cave at the Top of Shihua Cave
Figure 3-34 Milk Stone
4) Stagnant water deposition type: the aqueous solution rich in calcium carbonate flows at the bottom of the cave in the form of dripping, seepage and running water, and then gathers at the gentle place at the bottom of the cave. After a long period of alternation and supplement, it gradually deposited to form sedimentary forms such as moonstone, cloud basin, stony coral, chrysanthemum, hydrated calcium film and so on.
5) Water spray deposition type: When the aqueous solution rich in calcium carbonate drips from the upper fissure of the cave, it will splash into the cave or form fog and gradually deposit on suitable attachments, forming strange deposition forms such as stone needles, stone flowers, Stonefur, stone branches, pearls and rolling stones. Represented by the gorgeous "stone flower" deposited in the four-story cave of Shihua Cave, it is a rare sedimentary form in karst caves at home and abroad.
Figure 3-35 Shidun Formation
Figure 3-36 Huge stalactites
Figure 3-37 Stone Pillars
Figure 3-38 Stone Pipe
In addition to the various sedimentary forms formed by the above five sedimentary types, there are many superimposed transitional sedimentary forms. For example, stalagmites and stone flowers combine seepage and flowing water sedimentary facies, and transitional deposition forms undercurrent stones between flowing water and stagnant water. They are isomorphic to form a karst museum with complete sedimentary types.
Figure 3-39 Stone Grape
Figure 3-40 Stone Waterfall
(3) Discussion on the genesis of Shihuadong.
Shihua Cave is located in Xishan, Beijing, where there are favorable conditions for forming karst caves and redeposition types:
1) Shihuadong caves are all distributed in the limestone stratum of Majiagou Formation of Middle Ordovician in Paleozoic. Limestone is pure, accompanied by breccia limestone, containing soluble gypsum salt, which provides soluble rock for the formation of karst caves.
2) There is a sedimentary discontinuity of 150Ma between the limestone of Majiagou Formation and the overlying Carboniferous Taiyuan Formation. This unconformity interface provides a favorable channel for the later flowing water, and has enough time to scour the underlying limestone stratum and form a karst cave space.
3) There is Mesozoic Yanshanian magmatism in the south of the Geopark. Fangshan granite with an approximate circular area of more than 50 square kilometers squeezes the surrounding strata, forming a crescent-shaped Beiling syncline, multiple interlayer peeling fault zones and structural fractures in different directions, which provides favorable structural conditions for the formation of karst caves and sediments (Figure 3-4 1).
4) After the basic structural pattern of Xishan Mountain in Beijing was established by Yanshan Movement, the mountain area has been in the uplift period since Cenozoic Eocene. From the analysis of regional planation plane and the fourth terrace developed by Yongding River, it is basically consistent with the multi-layer karst cave structure of Shihua Cave, reflecting that the earth cave of Shihua Cave is controlled by the uplift activity of Xishan area in Beijing.
5) There is a winding big stone river in the northeast of Shihuadong National Geopark, and the good connection between surface water and groundwater has created the formation of karst caves in the south bank.
6) After the formation of caves, the climate in this area has been warm and humid since the middle and late Pleistocene. Forest coverage not only provides good climatic conditions for the formation of sediments in Shihua Cave, but also provides a good environment for the survival of Peking man and caveman, enabling them to coexist in space and time, which is another important feature of this park.