Rainbow Mountains of China are a landform of reddish sandstone that has been eroded to create magnificent rock formations with gorgeous colors. Zhangye Danxia, which means ‘rosy cloud’, is located around 600 miles west of Shanghai in the Gansu province, north-west China.
These mountains are part of the Zhangye Danxia Landform Geological Park in China, north of Qilian Mountains, also known as the „Red Stone Park”. It is a famous tourist destination in the region and is one of UNESCO’s unique World Heritage Sites. Landforms were included in the World Heritage List by the World Heritage Committee in 2010.
The core area of the park, Linze Danxia Scenic Area, is located 30 kilometers west of downtown Zhangye and 20 kilometers south of the seat of Linze County. It is the most developed and most visited part of the park.
Binggou is a second scenic area and is located on the north bank of Liyuan River. This area was officially inaugurated on August 3rd, 2014. Binggou covers an area of 300 square kilometers and its elevation ranges from 1,500 to 2,500 meters above sea level. A third scenic area, Sunan Danxia Scenic Area, is located in Ganjun, south of Linze.
How did the Rainbow Mountains of China form?
The Rainbow Mountains are Cretaceous sandstones and siltstones that were accumulated in China before the Himalayan Mountains were formed. The silt and sand were deposited with trace minerals and iron that provided it with the essential ingredient to form the colors we see today.
The colorful mountains were created over the course of 24 million years. Brightly colored layers of sandstone and minerals formed were crushed together under the earth and pushed to the surface as the tectonic plates shifted, creating the colorful patterns of rock strata.
This layering resulted in numerous rock colors as millions of years’ worth of sedimentary rocks formed and became composites, on top of sandstone beds and each other.
Wind and rain removed the overlying layers of continental siliciclastic rocks and exposed underlying formations with different chemistry and mineralogy. This causes the fascinating variation in colors seen across the Rainbow Mountains in China, including natural pillars, ravines, towers, waterfalls, and valleys– that differ in texture, color, shape, pattern, and size.
The deep red color is caused by the iron-rich mineral hematite (the mineral form of iron – Fe2O3), which oxidized when the rocks were formed. This is the exact same process that occurs when a piece of metal is left out in the rain and forms a red layer of rust around the outside.
The yellow colors are likely due to the presence of sand and clay, and the greenish-bluish-gray color may have come from organic plant matter or a mineral called glauconite, also known as „green sand”, which is usually found in marine environments. Glauconite is believed to be a diagnostic mineral indicative of continental shelf marine depositional environments with slow rates of accumulation. For example, it appears in Jurassic/Lower Cretaceous deposits of greensand, so-called after the coloration caused by glauconite.
This concludes that in the past, this area was the bottom of a huge lake, and many rivers brought sand of different colors.
The area has become a top tourist attraction for Zhangye. In 2005, this area was voted by a commission of reporters from 34 major media outlets as one of the most beautiful Danxia landform areas in China. In 2009 Chinese National Geography magazine chose Zhangye Danxia Landform as one of the „six most beautiful landforms” in China.