The Chinese "rainbow mountains" is one of the most beautiful natural attractions in the north east of China, and is near to the Zhangye town, in the Gansu province, with an area of 510 km2.About 540 million years ago, the area was once part of the ocean. Due to tectonic plate collision, the land folded and formed mountains, and lifted above sea level. Red sandstone was deposited when rivers formed in the area. When the ground sank into a basin, mudstone was deposited on the red sandstone. 

During different periods, varying sedimentary rocks were formed that contained different amounts of ferrous salt in the mud and stone - this is why the layers have different colors. Wind, rain and time made the erosion of the mountains, sculpting beautiful forms with different colors, patterns and sizes.

Since you are here, you can see the Ice Valley too :)

How to visit:

Inside, you need to use the sightseeing buses within the national park because no private cars or tourist buses are allowed and it takes 2–3 hours to finish the trip. The entrance fee for the geological park is around 7,50€ (entrance + sightseeing bus) and for the Ice Valley is a 10€ (prices are for adult).

If you want an excursion, you can search here:

https://www.viator.com/searchResults/all?text=Zhangye%20Geological%20Park&destId=

Happy journeys in China!