In 2017, one of the cliffs in the corner of a remote village in C̳h̳i̳n̳a̳ mysteriously produces an egg-shaped rock. The resulting eggs are 20-40 centimeters in size.
According to the locals, Chan Dan Ya (the Mandarin translation for ‘egg-producing cliff’) has 19ft high and 65ft long and every 30 years those round solid rocks emerge from the cliff face until they drop to the ground.
It all started in 2009, when local tourism bureau director Yang Shengjia encouraged members of the public to visit Chan Dan Ya, saying that tourists would be ‘astonished’ to see the mountain that lays eggs. However the cliff became famous eight years later.
The cliff is located in Qiannan Buyei and Miao Autonomous Prefecture, Guizhou Province bordering Guangxi to the south. The prefecture’s seat is Duyun. The closest village to the cliff has only 20 houses.
So far, about 68 odd egg-shaped rocks have been collected. Locals consider them good luck and collect them when they fall, but no one has known what, exactly, is responsible for this phenomenon.
Scientists are trying to figure out what causes this mysterious phenomenon. Although they have yet to come to a unanimous agreement, researchers hypothesize that the main cause is the erosion and hardness of the distinct rocks on the cliffs, but the precise geological mechanism at the cliff hasn’t been determined.
The cliffs are made of a type of limestone that was common around 500 million years ago during the Cambrian period. The stone eggs are believed to be made from sedimentary deposits that are harder and heavier.
This means that the cliffs tend to erode more rapidly on the egg part during prolonged rainfall or when landslides occur. The rock became egg-shaped probably because of the water flowing around it. But it is unclear how or why many of the stone eggs became embedded in the rocks.