China's deserts selected as World Heritage Sites: Uncovering the "Five Big Mysteries" of the Badain Jaran Desert

On July 26 and 27, local time, at the 46th UNESCO World Heritage Committee meeting held in New Delhi, India, the Badain Jaran Desert-Sand Mountain Lakes, China Yellow (Bohai) Sea Bird Habitat (Phase II), and "Beijing Central Axis-A Masterpiece of China's Ideal Capital Order" applied by my country were officially included in the World Heritage List. In just two days, three new world heritage sites were added, which is exciting and inspiring.

When we talk about deserts, we think of harsh environments with yellow sand everywhere and no human habitation. However, the Badain Jaran Desert is different. To put it simply, there are at least five "strange phenomena" in it.

Image source: Xinhuanet

01 Strange peaks stand tall: the unsolved mystery of the "Desert Everest"

The Badain Jaran Desert is located in the Alxa Plateau, a temperate desert area in the most arid area in northwest China. It is the third largest desert and the second largest mobile desert in China. Among them, the most praised natural landscape is the rolling sand dunes , which present various forms such as crescent, linear, star, dome and parabola. Under the influence of long-term directional winds, the positions of some sand dunes have gradually become fixed, and the height and size have gradually increased, so that they have changed from sand dunes to tall and majestic sand mountains .

Birutu Peak is the most famous sand dune among them. It is 1,617 meters above sea level and has a relative height of about 500 meters. It is also one of the highest fixed sand dunes in the world and is known as the " Desert Everest ".

There is still debate in the scientific community about the causes of the Birutu Peak and the numerous tall sand dunes in the Badain Jaran Desert. One view is that these sand dunes are formed by the accumulation of sand carried by the perennial southwest wind in front of the mountain . The wet sand layer 20 to 30 centimeters below the surface of the sand dunes contains a lot of water in the sand pores, which increases the humidity and fixity of the sand dunes , forming tall sand dunes over time. Another view is that the Badain Jaran area may have originally been a hilly landform, and after desertification, the sand directly covered the hills , forming tall sand dunes.

02 The sound of nature: the wonderful movement of the "Singing Sand Kingdom"

In Dunhuang, Gansu, there is a sand dune area called "Singing Sand Mountain" because of the buzzing sound it makes. In the Badain Jaran Desert, this phenomenon is also very common. Many sand dunes can make wonderful sounds under certain conditions and are called the " World Singing Sand Kingdom ."

The relative heights of the Singing Sand Mountains in the Badain Jaran Desert are between 200 and 500 meters. Some of them make sounds as melodious as string instruments, while others are as shocking as thunder. If you stand on the top of the towering sand dunes and slide down gently, you can hear the natural sounds from nature.

Why does the sand on the dunes "sing"? The scientific community has not yet reached a unified explanation. One theory is that due to the dry climate and lack of water in the desert, when the sand on the dunes slide due to wind or human factors, the pores between the dry sand (mainly quartz particles) will constantly change, and the air will quickly enter and exit the pores, causing vibrations and sounds; another theory is that the static electricity generated by the friction between the sand will stimulate the air to vibrate and produce sounds; and another theory is that the gullies and undulating sand peaks between the sand dunes form a natural resonance box, like a huge speaker, and the sound generated by the friction between the sand is amplified by the resonance box, forming a huge echo.

Badain Jaran Desert Summer Scenery

Image source: Xinhua News Agency (Photo by Beh)

03 Densely covered with lakes: the natural miracle of "Mobei Jiangnan"

In the seemingly barren sea of ​​sand of the Badain Jaran Desert, there are miraculously many lakes, forming a unique landscape of "South of the Yangtze River in the Northern Desert". According to incomplete statistics, there are more than 140 lakes in the Badain Jaran Desert, of which 74 are lakes with water all year round. These lakes vary in size and shape, some are as calm as a mirror, and some are rippling with blue waves.

The Badain Jaran Desert is located deep inland, far from the ocean, with little precipitation and strong evaporation. Why are there so many lakes in such a dry environment? The water in these lakes comes from groundwater. Geologists have found that there is a large-scale fault zone in the Badain Jaran Desert - the Altyn fault zone, which is composed of multiple faults hundreds of kilometers long and has a total length of more than 1,600 kilometers. Because the rock strata in the fault zone are broken and have good water conductivity, the meltwater from the mountains flows continuously to the Badain Jaran Desert through the groundwater recharge channel, and finally gathers into a lake in the low-lying area.

In the hot summer, the lakes in the Badain Jaran Desert are a cold source relative to the sand dunes. But in winter, the lakes here do not freeze, and the surface temperature in the lake area is significantly higher than other areas, which can regulate the local temperature to a certain extent, showing a peculiar " warm island effect ".

In summer, the evaporation of the lake becomes more vigorous, resulting in higher and higher salinity. Many organisms die because they cannot adapt, but algae that can adapt to the high-salinity environment and Artemia that feed on algae multiply in large numbers, causing the lake water to appear charmingly pink. For example, Dagtu Lake, which is called the "Red Sea" by the locals. Because the lake is usually pink as the main color, mixed with other colors (such as precipitated white salt, etc.), and changes with the seasons and water volume, it is also known as the "Rose Lake".

The scenery of the Pink Lake deep in the Badain Jaran Desert in Alxa League, Inner Mongolia

Image source: Xinhuanet (Photo by Wang Zheng)

04 The gushing spring of God: the source of life in the heart of the desert

Most of the lakes in the Badain Jaran Desert are saltwater lakes , which is caused by the dry climate, strong evaporation of lake water, and gradual accumulation of salt. However, in this saline-alkali land, there are miraculously several freshwater lakes , whose water supply may be more stable and pure, providing precious freshwater resources for life in the desert.

According to news media reports, there are many small freshwater lakes formed by springs in the southeast of the Badain Jaran Desert. The average depth of these waters is 3 meters, which is very beneficial to the development of fishery production. In 1979, local people established a fishing ground here and harvested a lot. For example, Badain Lake, the gateway to the Badain Jaran Desert, is a rare freshwater lake with abundant fish. Local people often organize fishery enhancement and release activities, which also plays an important role in protecting aquatic biodiversity and improving the ecological environment of the waters.

The reason why there are freshwater lakes in the Badain Jaran Desert is due to the gurgling springs. They are usually hidden at the bottom of the lake that we can hardly see, and they continuously inject clear and sweet fresh water into the lake day and night, thus maintaining the salinity balance of the lake. Sometimes, they will also emerge from the lake. In Yinderitu Lake (also known as "Miaohaizi"), there is a solitary stone of only about 3 square meters, with hundreds of tiny springs on the stone, which continuously gushed out spring water day and night, and is called "Holy Spring" by the locals.

05 Strange rocks: "natural sculptures" created by wind

In the Gobi Desert on the northwest edge of the Badain Jaran Desert, there are many strange stones of various shapes. Locals call them "Haisenchulu", which means "pot-like stones" in Mongolian. When you walk into this strange stone forest, it feels like you are in a huge natural sculpture park. Some of the large and small stones look like huge mushrooms, some look like cute monkeys, some look like crocodiles with bared teeth and claws, and some look like eagles with wings spread... Whenever a strong wind blows, the sound of the wind changes due to the obstruction of the stone wall, and the pitch varies, adding to the mysterious atmosphere of the strange stone forest. In fact, the Haisenchulu strange stone forest is a typical wind erosion landform , that is, a landform formed by the destruction of surface rock and soil by wind.

Tourists visit the "Haisenchulu" strange rock forest in Alxa League, Inner Mongolia.

Image source: Xinhua News Agency (Photo by Wang Jiang)

The formation of the Haisenchulu rocks is a complex and long natural process. According to experts, the rocks here are granite , which is an igneous rock formed by the cooling and solidification of magma deep in the earth's crust. With the movement of the earth's crust, it was eventually exposed to the surface. After that, under the action of strong winds, it became the strange appearance it is today.

Some scholars also believe that salt crystallization also plays an important auxiliary role in the formation of strange rocks, which is called salt weathering . The salt on the surface of the rock seeps into the cracks with water, and then crystallizes into salt particles under dry conditions. The volume expansion produced during the crystallization process will exert pressure on the particles on the surface of the rock, causing the rock to crack or fall off, and finally forming bumpy weathering holes.

In addition to the above, the Badain Jaran Desert has also nurtured many animals and plants with its unique desert environment, forming a unique biodiversity. What is even more striking is that the Mandela Mountain rock paintings in the desert are like a hidden treasure, carrying profound cultural and historical connotations, quietly telling the glory and vicissitudes of the past. Now, it will be presented to the world as a new world heritage site, attracting more people to experience the shock and beauty of the desert wonders in person.

Author: Ma Zhifei, a popular science writer and member of the Beijing Science Writers Association, has written more than 10 popular science books, including "A Dream of Red Mansions" and "Glass Earth". He has won the Ministry of Natural Resources' Excellent Popular Science Book Award, the Wu Dayou Popular Science Book Award, and the China Natural Resources Writers Association's "China Gem Literature Award" Popular Science Works Award.

Reviewer: Li Zhongdong, Deputy Director of Sichuan Geophysical Survey Institute, Chief Science Communication Expert of the Ministry of Natural Resources, Director of China Science Writers Association, Chief Expert of Earth Science Talent Program of Sichuan Institute of Geology and Survey

Produced by: Science Popularization China