Zhangye Danxia National Geological Park is in the eastern foothills of the Qilian Mountains in Gansu Province, China. The geological park has a spectacular Danxia (‘red cloud’) landform area that covers about 50 square kilometers. The danxia landforms are a masterpiece of nature. The colorful mountain ridges are just like an overturned palette from heaven.
Zhangye’s Danxia landscape has lots of precipitous red cliffs, most of which are several hundred meters high, and multicolored ridges of weathered strata, sometimes stretching to the horizon. These formations, sometimes smooth sometimes sharp, stand out against the greens or grays of the plains, looking grand and magnificent, vigorous and virile.
They are the result of deposits of sandstone and other minerals that occurred over 24 million years. The result (similar to a layer cake), was tilted by the action of the same tectonic plates responsible for creating parts of the Himalayan mountains. Wind, rain, and time then sculpted extraordinary shapes, including towers, pillars, and ravines, with varying colors, patterns, and sizes.
Because of the changes in sedimentary environments, the sedimentary layers formed have different colors red, purplish red, yellowish green, grayish green, and gray. Every layer took thousands of years to form.
The movement of the Himalayas lifted the area higher and rivers formed. The river erosion formed gorges, and the early Danxia landscape was created. After further geological periods, river erosion and wind erosion formed the colorful layers we see today.
In 2009, Chinese National Geography magazine chose Zhangye Danxia as one of the “six most beautiful landforms” in China. The area has become a top tourist attraction for Zhangye. A series of boardwalks and access roads have been built to help visitors to explore the rock formations. In 2014, 100 million yuan was invested to improve the facilities in the Binggou area.
The best time to visit Zhangye is from June to September when the weather is comfortable, and the combination of strong sun and a little rain brings out the colors more. The rest of the year is very dry.
According to Wikipedia