The rainbow is a common natural phenomenon, but people still fancy it because it vanishes quickly. But there's another rainbow that lasts much longer and are also loved by many – Zhangye Danxia, the rainbow hills of China. 

Zhangye Danxia is a danxia landform that can be found in Zhangye National Geopark. Located at Zhangye City, northwest China's Gansu Province, the hills cover an area of 322 square kilometers. From the sky, the vast land is covered with red cliffs in different shapes and rainbow ridges in multiple colors.

How was the danxia landform in the geopark formed?

Zhangye Danxia landform's geomorphic development happened in about Jurassic period. It is a result of red sandstone erosion, together with its geological structure and long-term desert conditions, wind and water erosion. During the mid-Cretaceous age, iron and other elements contained in the sediment started to exchange and oxidize, which formed different layers of colors in different strata.

The ferruginous rocks are red, the argillaceous rocks are gray, the phosphatic rocks are grayish-blue, the volcanic rocks are orange-yellow, and the pebbly rocks are cyan. All of the colors are intertwined in these magnificent rainbow hills.

In Chines history, Zhangye City is part of the Hexi Corridor, which is an important route for connecting China to the Western world in Gansu Province via the Silk Road. 

Marco Polo spent a year here around 1274 and wrote in his book "The Travels of Marco Polo" that this region was an international trade market. Nowadays, it has turned into a tourism city that attracts many people. June and July each year are the best months to visit Zhangye National Geeopark. During the rainy season, the water can cool you from the summer heat and add moisture to the air.

(Cover image is still from video)

(If you want to contribute and have specific expertise, please contact us at nature@cgtn.com.)