Three years ago, a shocking geographical discovery was made– a group of sinkholes of unimaginable scale was discovered in Hanzhong, Shaanxi Province.
As of April 2019, after several scientific expeditions, the official finally set the tone for it: The Hanzhong Sinkhole Group is the world's largest "Sinkhole Group" geological relics, with a total area of 5019 square kilometers, and appears in groups, a large number, so far 4 sinkhole groups of 54 sinkholes, 316 caves, 23 shafts, 25 funnels, concentrated in Hanzhong 4 plateaus, accounting for nearly 1/4 of the total number of global sinkholes, is deserved "the world's first sinkhole group".
In addition, the largest sinkhole of single scale is the Zhenba Sanyuan Circle Cliff Sinkhole, with a maximum caliber of 520 meters and a maximum depth of 320 meters, which is equivalent to a football field with 75 floors underground.
It was in Shaanxi
The Hanzhong sinkholes are so valuable, it is difficult for everyone to imagine how they were discovered. Why is there a great geographical discovery in the hinterland of Chinese civilization in the 21st century?
Photo/Geology of Sanqin
The Hanzhong sinkholes are so stunning that it's hard to imagine that their discovery was originally related to a satellite photograph.
In April 2016, the Land and Resources Department of Shaanxi Province organized the implementation of the geological relics survey in the province, and the staff of the Shaanxi Provincial Geological Investigation Center initially discovered the sinkhole through a satellite photo, using remote sensing interpretation and analysis, drone aerial photography and other methods.
The whole sinkhole is distributed in groups, mainly in four areas: Chanjiayan Town, Ningqiang County, Xiaonanhai Town, Nanzheng County, Luojiaba Town, Xixiang County, and Sanyuan Town, Zhenba County. Among them, the South Zhenghe Zhenba Tiankeng group is the most dense, reaching 23 and 19 respectively. Some of the pits are more than 100 meters in diameter and more than 150 meters deep, and standing on the hill made of collapsed objects at the bottom of the sinkhole and looking up, one can't help but feel the grandeur of nature and the smallness of human beings.
Such a sinkhole may not be too surprising if it appears in Guangxi or Guizhou, which is famous for its sinkhole landform, but in fact, it appears in Hanzhong, and more importantly, a sinkhole of this scale is only a very ordinary existence in the Hanzhong sinkhole group.
Since then, a number of senior engineers have formed the first expedition team of the Hanzhong Sinkhole Group, began field investigation, and unanimously agreed that its resource endowments such as typicality, originality, rarity and integrity are excellent, and it has a variety of values such as scientific research, scientific expeditions, sightseeing and tourism, and has reached the standard of world-class geological relics. Internationally renowned cave explorer Jean Potassi praised it as "the most beautiful sinkhole in the world!" after inspecting the Ningqiang Zen family Rocky Cave River Sinkhole! ”
The primeval forest hides the mysterious sinkhole
The oldest of the Hanzhong sinkholes, the oldest dating back to 680,000 years ago, is that they are all in primeval forest.
China's karst landforms are the most famous "South China Karst" World Natural Heritage, those distributed in Yunnan, Guizhou, Guangxi, Chongqing and other places of stone forest, peak cluster, caves, Tiansheng bridge and sinkholes, etc., regardless of their own landscape value, in the environment in which they are located, there is no longer a rich and lush primary forest in the Hanzhong Sinkhole Group.
In the sinkholes hidden in the primeval forest, internal chemical sediments abound, such as tall stalagmites, stone forests, stone fields, stone pearls, etc.
What is even more amazing is that for thousands of years, a unique primitive microclimate has been formed inside the sinkhole, and the animal food chain and unique living environment inside are irreplaceable.
Flying cat found in Hanzhong Sinkhole/China Geological Survey
The animals and creatures found here include the "Sophie Grey Butterfly", "The Great Pink Butterfly", "The Elephant Cicada", "The Green Golden Turtle", "The Lily Family Big Lily" and so on.
Among them, the flying cat is a unique animal in the Hanzhong sinkhole, the flying cat is called the shrew, also known as the "six unlike", the face is like a fox, the eyes are like a cat, the pointed-billed rat, the ears are like a rabbit, the claws are like ducks, and the tail is the same as the squirrel. It can glide between cliffs and large trees by the wide fins between the front and back legs, and the maximum head and tail length can reach 1 meter and weigh more than 7 pounds. This animal is very shy, day and night, coupled with the increasing rarity, it is not easy to see flying cats with your own eyes.
Discover the underground dark river
In the Hanzhong sinkhole group karst system, there are not only large and small sinkholes, but also undercurrents of underground rivers, interconnected caves and so on. The caves contain large-scale underground cave halls and a variety of cave sediments, which are of great significance for revealing the relationship between surface water flow changes and the development of underground caves in the region, the relationship between underground morphology and surface morphology, and the relationship between hanzhong basin faults and cave canyon formations.
Expeditions investigate the structure of the sinkhole at the bottom of the sinkhole/China Geological Survey
Among them, the underground river sinkhole located in the falling water village of Chanjiayan Town, Ningqiang County, Shaanxi Province, is very spectacular.
The cave in the sinkhole of the Cave River is the largest cave found in the north subtropics of China and its north so far, and the collapsed rubble and the endless flow of underground dark rivers can be seen everywhere in the cave, and the cave itself is at the upper end of a number of underground dark rivers, and there are larger and more turbulent dark rivers flowing underground.
In May 2018, the Chinese-Czech scientific expedition conducted a joint scientific expedition to the Hanzhong Sinkhole Group for the fourth time.
The Czech team of 11 people was divided into 3 groups, and the underground diving, rubber boat rafting and cave single rope technology were used to conduct cave exploration on the underground river system, tianxing rock cave system and Boniu pit cave system in the Small South China Sea. The Chinese team of 29 people undertook the supplementary exploration of the Dafo Cave System and the Xigou Cave System, and systematically sampled the cave sediments in the Taiyuan area of the Little South China Sea.
The newly discovered caves in this scientific expedition are 15.3 kilometers, of which 6224 meters are newly discovered in Tianxingyan, including 2 cave halls; 407 meters are newly discovered caves in Boniu Pit; 1036 meters are newly discovered caves in Xiaonanhai Guanyin Cave, which is the main underground river drainage system of Big Buddha Cave; 584 meters are newly discovered caves in hanging caves; 5547 meters are newly discovered in The Branch Caves of the Newly Discovered Big Buddha Caves, and 1442 meters of Xigou Caves are detected. The newly discovered cave passage of the underground river system of the Big Buddha Cave is more than 1,000 meters and is connected to multiple cave halls, indicating that the cave system of the Big Buddha Cave has more developmental stages and is larger than the early cognition.
The Czech team conducted a tracing experiment in the small South China Sea underground river/Sanqin Geology
The scientific expedition team put fluorescein sodium tracer in Boniu Pit, and received samples from the underground river outlet of Dafo Cave, Guanyin Cave, Baishui Cave and Dragon King Temple Cave, and the experimental results will reveal the excretion pathways and underground watersheds of the cave system in the Original Area of NanzhengTaiyuan, providing another strong evidence for revealing the development of karst caves and sinkholes.
Saber-toothed elephant fossils were found
During the team's latest expedition, a saber-toothed elephant fossil was also accidentally found.
Organized by the China Geological Survey of the Ministry of Natural Resources, the project team traveled through muddy shrubland, descended nearly 100 meters from the sinkhole to the bottom of the underground river canyon, and accidentally found this paleontological fossil in the process of creeping through low cracks and waterholes to trace the source of the underground river.
The surface of the huge tooth fossils is ridged and raised, like the grooves of the washboard, and the surface of the fossils is crystal clear, like jade, and looks very strong and wear-resistant; these huge horizontally arranged tooth fossils are immediately reminiscent of the teeth of mammoths, and the project team members continue to search upstream along the ditch, and then find a hollow suspected elephant incisor fossil and two huge molar fossils, and several limb bone fossils scattered in the rubble and sediment.
Fossils of eastern saber-toothed elephants/Geology of the Three Qins
The saber-toothed elephant fossils found this time are the first time such fossils were found in the Hanzhong Basin in the 1980s, and it is also the first time that saber-toothed elephant fossils have been found in the Hanzhong sinkhole group caves. Saber-toothed elephants are ancient mammals endemic to Asia, living in the Late Miocene to Holocene from 6 million to 10,000 years ago, widely distributed in the area south of 38° north latitude, and are the "Big Mac" after the dinosaurs. It seems to be inferred that the Hanzhong giant panda was accompanied by the Hanzhong saber-toothed elephant for a long time; the Hanzhong Longgang people once lived in harmony with the Hanzhong saber-toothed elephant.
A new chapter in conservation and utilization
In April 2019, the "Hanzhong Sinkhole Group International Research Base", "Resource Origin Scientific Research Practice Base" and "Natural Resources and Ecological Civilization Research Center" have been established one after another, marking a new height in the investigation and research, planning and construction of The Hanzhong Sinkhole Group, and opening a new chapter in the protection and utilization of the Hanzhong Sinkhole Group.
"2019 Hanzhong Sinkhole Group Sixth International Joint Scientific Expedition Results Symposium"
Another important information released by the meeting is the tourism route planning: the geological tourism route of the Xiaonanhai area in Nanzheng District and the geological tourism route of the Ningqiang Chanjiayan Tiankeng Group were preliminarily determined;
Landscape geography investigation and planning were carried out on the steep cliffs of Longtou Mountain, Boniu Sinkhole, Tianxingyan Underground River, Baishuidong Spring Water and Houhe Village Peak Forest. The feasibility assessment of the construction of geological and cultural villages in Qingshiguan Village and Qinjiaba Village was carried out, which played a role in promoting the development of local tourism.
The large-scale scientific expedition of the Hanzhong Sinkhole Group, which lasted for 3 years and 6 consecutive times, unveiled the mystery of the Hanzhong Sinkhole Group and explored the basic types, distribution characteristics and cause mechanisms of the sinkholes. The Hanzhong Sinkhole Group has different formation mechanisms from the Southern Sinkhole Group, and the biological diversity is also very unique, so from the aspects of rarity, science, aesthetics, and protectability, the Hanzhong Sinkhole Group has the conditions to become a world-class geopark.
On this basis, can the comprehensive investigation of natural resources in the Hanzhong Sinkhole Group area be strengthened to promote its declaration as a global geopark and a world natural heritage? How to develop the Hanzhong sinkhole group in the protection, I believe that the local government department will have a set of perfect planning.
Synthesized from China Geological Survey/National Geographic
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Shaanxi Daqin Law Firm