【Haichuan Chemical Industry Site】Tenglong Cave Nitrate Cave Site in Lichuan, Hubei
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Tenglong Cave is located at the junction of the Daba Mountains and Wulingyuan, at the source of the Qingjiang River. It is 6.8 km away from the urban area of Lichuan City. It is considered the largest karst cave in China and one of the world’s top-class caves. The total area of the Tenglong Cave Park is 69 square kilometers; it starts at the entrance of Tenglong Cave in the southwest and is connected to the Mingyan Gorge scenic area ； It extends to the edge of the dark abyss and is connected to the Xuezhao River Gorge scenic area; overall, it stretches from southwest to northeast and is a narrow scenic zone that runs along the Qingjiang River valley. The elevation throughout the area is above 1,000 meters.
Tenglong Cave is the largest single cavern in the world; its entrance is 74 meters high and 64 meters wide, with the highest point inside the cave reaching 235 meters. The area of this cave exceeds 2 million square meters. Inside the cave, there are 5 peaks, 10 halls, and over 10 underground waterfalls. Tenglong Cave is enormous in size and magnificent in appearance. Looking inside from the entrance, it seems infinitely deep; no one dares to enter recklessly ； According to Professor Zhang Shouyue from the Chinese Institute of Geology and Geophysics, in 2006, the Tenglong Cave scenic area invited helicopters from a military unit to arrive at Tenglong Cave in order to fly inside it; however, due to the complex wind conditions at the cave entrance, they were unable to enter. It is thus conceivable that the entrance to Tenglong Cave is indeed huge.
Looking out from inside the cave, one feels that both the sky and the river seem narrower. Opposite the cave entrance lies a mountain whose shape is similar to that of the cave entrance. According to local legends, in ancient times this mountain was connected to Tenglong Cave, blocking the path of the river water. On a snowy and stormy night, Zhang Guolao, one of the Eight Immortals, used his magical powers to move the mountain to the other side. In Tenglong Cave, the water caves are connected to the dry caves, and the main cave is linked to its side caves. The temperature inside the cave remains constant at 14–18°C throughout the year, with ample and smooth airflow. The dry cave is 59.8 kilometers long, making it the largest dry cave in Asia. The water cave absorbed all the water from the Qingjiang River, resulting in a waterfall that is over 50 meters wide and more than 30 meters high; the water from the Qingjiang River then turned into an underground stream stretching 16.8 kilometers long. The Qingjiang River water enters through the water cave, flows underground through the mountains, and emerges back to the surface from the dark hole. Caves filled with water and those without water are stacked one upon another, passing through mountains underground to form a self-contained underground world of great scale.
Tenglong Cave was formerly known as Gandong and Xiadong. The Guangxu edition of the “Lichuan County Annals” records: “Qian Dong has nitre.” In the 10th year of the Guangxu era (1884), “more than a dozen people who went to collect nitrate entered an area dozens of miles away carrying candles, but they returned out of fear.” Aside from the section from the cave entrance to Yuan Tang Pass, which was somewhat known to ancient nitre miners, many legends have surrounded Tenglong Cave over the years; in people’s minds, it has always been a huge and mysterious entity. It was not until 1985, when Professor Zhang Lianggao from the Department of Ancient Architecture at Huazhong University of Science and Technology published his article titled \"Leshui Cave in Lichuan Should Gain World Recognition,\" that it triggered a wave of enthusiasm; this led to a surge in interest in exploring Tenglong Cave in Lichuan.
On both sides of the walls of Tenglong Cave, there are traces of water erosion in the form of wavy lines caused by years of heavy subterranean water flow. At an elevation of 20–50 meters on the cave walls, visible signs of long-term water erosion can be seen. A few meters away from these clearly marked areas of water erosion at a height of over 20 meters, there is another line of erosion with a slightly lesser degree of wear and tear; this is likely the area that was affected by floodwaters, which is why the erosion there is less severe. It proves that Tenglong Cave was indeed an underwater cave in ancient times. If Tenglong Cave is completely submerged, it is generally over 100 meters high; during the dry season, the flow rate of the entire Yangtze River poses no problem, as there are numerous subsidiary caves that can help distribute the water flow.
The huge corridors of Tenglong Cave also provide an excellent research site for determining the relationship between the rate of crustal movement and changes in the karst water system. The complete karst landform-hydrological system comprising both surface and underground elements in this area serves as a natural laboratory for studying the formation mechanisms of large caves, as well as the evolutionary history of rivers and phreatic flows. Nearly half of the side caves in Tenglong Cave remain undiscovered to this day. “It is precisely because of peculiar underground river caves like Tenglong Cave that the 800-li Qingjiang River can flow straight downstream without any obstacles, giving rise to the splendid Bashu culture we see today. ”Professor Yan Zhiwu believes that: “Studying the geological structure and formation of Tenglong Cave is, in essence, studying the developmental and evolutionary history of the entire Qingjiang karst system.” (Quoted from Yangtze River Business Daily)
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