[Explanation] It is the beginning of autumn and the heat has not yet faded. On Guancen Mountain, 2800 meters above sea level, Ningwu County, Xinzhou City, Shanxi Province, Wannian Ice Cave attracts many tourists.

The ice cave was formed during the fourth glacial period of the Cenozoic and has a history of 3 million years.

On September 18, the reporter walked into this crystal palace that never changed forever along the downward steps in front of the Wannian Ice Cave.

  The stone steps in front of the ice cave entrance are covered with green grass. Stepping into the cave entrance, the temperature drops sharply, and you immediately enter a world of ice.

  [Concurrent period] Yan Peng, director of the Ningwu County Cultural Tourism Bureau: Like Mount Everest, where the ice does not melt throughout the year, that place belongs to the permafrost.

In our place, our local environment cannot be frozen at all, but the ice in our cave does not melt throughout the year.

The Wannian Ice Cave in Ningwu is actually warm in winter and cool in summer, because the temperature outside our cave can reach more than minus 20 degrees in summer, and the temperature inside our cave is always around minus 4 degrees. In winter, our cave The outside temperature can be as low as minus 30 degrees, but the temperature inside our cave is always minus 4 degrees to minus 6 degrees. Wannian Ice Cave is a constant temperature throughout the year.

  [Explanation] There are wooden steps in the Wannian Ice Cave. Walking along the wooden steps, icicles, ice curtains, ice waterfalls, ice bamboo shoots, ice flowers, and ice grapes are dazzling. These magical works of heaven change with the light, beautiful Beautiful.

The ice cave cavity is huge, basically in the shape of a vertical barrel. It has been developed for nearly a hundred meters. The deeper it is, the thicker the ice will be. The freezing period is mainly in summer and the melting period in winter.

  Surprisingly, there is an active volcano about 400 meters south of the ice cave.

According to historical records, the volcano here has been burning since the Song Dynasty and has a history of more than 1,000 years.

Along this mountain range, there are five volcanoes burning. The fire area is more than ten meters in diameter, surrounded by hot sand and terracotta, and no grass grows.

  [Concurrent] Yan Peng, Director of the Ningwu County Cultural Tourism Bureau: Our thousand-year land fire is not a volcanic eruption. It belongs to the spontaneous combustion of coal. The sulfur content is relatively large, mainly because the coal seam is very thin. When it sees sunlight, it is because of the optical reaction of sulfur with the sun, it will spontaneously ignite.

  [Explanation] Why is there such a geological wonder?

Experts have different opinions, including glacier movement theory, air convection theory, geothermal negative anomaly theory, self-shape theory, and so on. So far, no consensus has been reached.

  [Concurrent] Yan Peng, Director of the Ningwu County Cultural Tourism Bureau: According to when we developed the Wannian Ice Cave, we invited experts from the Institute of Geology of the Chinese Academy of Sciences. It may also be because we have changed the geological and landform structure due to thousands of years of ground fire, and this environment can be naturally frozen.

There are also many other scientists who have come to explore the secrets now. There are different opinions about the formation of the ice cave for thousands of years. We are still exploring and exploring.

  Qu Lixia and Cao Jianguo report from Xinzhou, Shanxi

Editor in charge: [Tang Weijie]