Chongqing's hidden jungle

Under the surface of Chongqing, an immense cavity shelters a unique jungle. This chasm, 128,000 years old, is the refuge of rare leopards and unknown plants. Seen from above, the karst terrain of the Chinese city of Chongqing appears pierced by a giant hand. Under this vertical opening plunging into shadow, the Xiaozhai Tiankeng chasm conceals a lost world where species have thrived cut off from the surface.

Size of the chasm

A cavity capable of swallowing the Eiffel Tower twice has been identified. With its 626 meters of depth and 527 meters of width, this monumental hole would swallow two Eiffel Towers stacked on top of each other and would allow one and a half times the London O2 Arena to pass through its opening. Its volume approaches 120 million cubic meters, equivalent to 40,000 Olympic swimming pools.

Location and discovery

The chasm is located in the county of Fengjie, about 250 kilometers northeast of Chongqing. The villagers have known the cavity for centuries, but it was only in 1994 that Chinese geologists precisely measured its dimensions. The toponym refers to an abandoned hamlet, while Tiankeng means "celestial well" in the local karst vocabulary. The size of the opening places this site well above other chasms recorded on the planet.

Formation of the chasm

The collapse dates back to about 128,000 years ago. For tens of thousands of years, rainwater acidified by atmospheric CO₂ has seeped into the porous limestone of the underground, dissolving the rock and widening the cracks. In parallel, an underground river 8.5 kilometers long has carved a network of galleries known as the Difeng Cave, losing 364 meters in elevation along its course. When the rock vault could no longer hold, the ceiling gave way.