One of the world's natural wonders is the Rainbow Mountains of China, which are part of the Zhangye Danxia Landform Geological Park. The unusual hues of these well-known Chinese mountains are said to resemble a rainbow painted across the crests of undulating peaks. Situated in the northwest of China, in the Gansu province, is the 200 square mile Zhangye Danxia National Park. Due to its 2009 UNESCO World Heritage designation, the location attracts a large number of Chinese and foreign visitors. Zhangye Danxia was named one of the "six most beautiful landforms" in China by the Chinese National Geography magazine.

Before the Himalayan Mountains formed, cretaceous sandstones and siltstones were deposited in China, creating the Rainbow Mountains. Iron and trace minerals that were deposited in the sand and silt gave it the essential component needed to create the hues. Approximately 55 million years ago, the Indian Plate collided with the Eurasian Plate, upending a previously stratified, horizontal, and flat strata.

Mountains were raised by this process, revealing sedimentary materials that were previously concealed far below the earth's surface. The continental siliciclastic rocks' upper layers were eroded by weathering and erosion, revealing beneath formations with distinct mineralogy and chemistry. The Rainbow Mountains' remarkable color variety is the result of this.

Sandstone grains are penetrated by precipitated groundwater, which deposits trace minerals in the spaces between the grains. The grains may become cemented in place if this precipitate accumulates to the point where there is no longer any pore space between them. This process gives sandstones all over the world their ethereal tint and imparts the trace minerals listed below. The predominant hue is a rich crimson stone.

The months of June through September are the ideal times of year to travel to the Rainbow Mountains. The mountain's colors can be intensified and its attractiveness can be further enhanced by moderate summer rainfall that helps lower the sky's intense temperatures. When the colors change in the evening, it's the ideal time of day to see this magnificent spectacle. 

When visitors encounter this landscape for the first time, they think it's an impressionistic painting. The predominant hue of the terrain is red, which is reminiscent of fire. The cementation between the sandstone grains and the iron oxide layer give it its red color. Additionally, several of the mountains feature stripes that resemble ribbons.

The mountains are becoming Zhangye's most popular tourist destination. To facilitate tourists' exploration of these intriguing rock formations, a number of access roads and boardwalks have been constructed. In fact, the site sees 20,000 visitors each day during the busiest travel season.