Why are some mountains as red as fire?
In the novel Journey to the West, Tang Sanzang and his disciples traveled all the way to retrieve the scriptures, and eventually came to the perilous Fire Mountain. Only by borrowing a magic fan from Iron Fan Princess, the wife of the Bull Demon King, could they extinguish the blazing fire and continue their journey. Although the Fire Mountain in Journey to the West is just a mythical legend, there are indeed many mountains in our world that are as red as fire, one of the most representative of which is Danxia Mountain in China.
In Shaoguan, Guangdong, a 290-square-kilometer red mountain range "as red as wax and as bright as the setting sun" is located. Peaks, cliffs, and valleys everywhere show vivid red hues; under the setting sun, the red sand gravel of Danxia Mountain shines brightly, enchanting people. In 1928, Chinese geomorphologist Feng Jinglan named this extraordinary landscape "Danxia Landform", and Danxia Mountain has since become a synonym for similar geomorphological features and scenic mountains around the world. Since then, many scholars have elaborated on its concept.
Danxia landforms are mainly distributed in China, the western United States, central Europe, and Australia, with the most extensive distribution in China. In addition to Danxia Mountain in Guangdong, Chi Shui in Guizhou, Taining in Fujian, Lang Mountain in Hunan, Longhu Mountain (including Turtle Peak) in Jiangxi, and Jianglang Mountain in Zhejiang are all typical Danxia landforms. These six sites, collectively known as "Chinese Danxia", have been approved by the UNESCO World Heritage Committee and listed as World Heritage Sites.
In fact, there are more than 6 Danxia landforms in China, with over 800 having been discovered so far. Generally, any land-based red sand gravel rock formation with steep cliff slopes can be called a Danxia landform. The necessary conditions for the formation of this landform are the existence of a thick layer of sand gravel rocks, with regular cracks visible in the rocks, and the direction of the cracks extending roughly perpendicular to the ground. On the cliffs, one can see layers of rocks with distinct coarseness and fineness, with the coarse layers called "gravel rocks" and the fine and uniform layers called "sandstones".
Taking the formation of Danxia Mountain as an example, between 140 million and 70 million years ago, it was once a large inland basin. Due to the Himalayan orogeny, the surrounding mountains rose sharply, and the basin received a large amount of sedimentary debris (red sand gravel), forming a thick layer of red rock. Around 70 million years ago, the crust rose and was gradually eroded. Since 6 million years ago, the basin has undergone multiple intermittent uplifts, with an average uplift of about 1 meter per 10,000 years. At the same time, water eroded and cut into the ground, and the Danxia rock layers were cut into a red mountain range. Now, the entire Danxia Mountain area is red, appearing as if it were on fire.