Back to quicksand, only pine trees and thorns are growing. Compared with the endless deserts in California, Nevada and Arizona, this small desert is very interesting. It has the basic characteristics of a desert, but at first glance it is two kilometers wide and can be crossed in a few minutes by car.
Comprehensive view of desert family
Desert is commonly known as "dry sea" or "desert", which is called Qom in Uygur, Gobi in Mongolian and Manchu, and Erg in Arabic.
In fact, people often confuse the concepts of "desert" and "desert". From the perspective of physical geography, all areas with dry climate, scarce rainfall, sparse and low vegetation and barren land are called "deserts". The composition of desert surface is stony, gravelly, sandy, argillaceous and salty, with different types.
Rock desert is usually called rock desert, which is formed by long-term exposure, leakage and weathering of rocks. Its surface composition is mostly rough weathered rocks and gentle bedrock outcrops. Common small-scale wind erosion landforms include mushroom rock, wind candle pit, wind erosion cave and wind erosion residual hill. Gravel desert is usually called gravel desert, and its surface material composition is mainly gravel mixed with sand, which mostly appears in the inclined plain at the foot of the mountain. There are two forms of formation: alluvial and diluvial. Due to good water conditions, the vegetation coverage rate of gravel desert can reach 10% ~ 30%. Geographers usually refer to rocky deserts and gravel deserts as Gobi.
Mud desert and salt desert are called mud desert and salt desert. The former is composed of clay, mostly located in low-lying areas or the center of closed basins; The latter is mostly located in the lower reaches of rivers and around lakes, with strong evaporation and serious salinization. Generally speaking, there are no plants growing or only sparse halophytes.
The sandy desert covered by large sand dunes and the sandy land on its edge are commonly called deserts, which are generally caused by wind. The sand dunes on the desert surface, regardless of size, have the phenomenon that mounds move along the main wind direction. According to the degree of sand dune activity, geographers generally divide deserts into mobile dunes (with sparse vegetation, the coverage rate is below 10%, or even completely exposed), semi-fixed dunes (with vegetation coverage rate of 10% ~ 50%, and scattered quicksand on the surface of mounds with significant sandstorm activity) and fixed dunes (with vegetation coverage rate above 50%, and sandstorm on the surface of mounds) In addition, there are many areas covered by sand dunes in grassland areas outside the desert zone, which is what is customarily called sand. Because of its desert-like nature, it is also commonly called desert.
Because the desert is far more famous than its brothers and sisters, the word "desert" mentioned by the public today is equivalent to "desert" in a broad sense.
Where did Nie's yellow sand come from?
A dry climate is a necessary condition for desert formation. In addition to dry conditions, the formation of desert also needs rich sand sources, so as to form desert with the help of wind erosion, transportation and accumulation. So, where does the huge amount of yellow sand come from?
It is generally believed that. There are several main sources. (1) Take sand on the spot. Residues such as alluvial deposits, lake sediments and rock weathering debris caused by rivers and floods may become sand sources under certain natural environmental conditions. (2) Stones from other mountains. Because the wind is one of the main driving forces to form a desert, it is inevitable to bring some "foreigners". Things have changed. Because the dry climate is the main cause of desert formation, the alternation of cold, hot, dry and wet during glacial and interglacial periods since Quaternary, that is, climate change, directly affects the emergence, disappearance, expansion and contraction of desert. ④ Desertification. It is generally understood abroad that desertification usually refers to the process of desert or desert-like formation in arid, semi-arid and partially semi-humid areas, due to the influence of climate change and human activities, the ecological environment is destroyed, and the land productivity is reduced or lost. In our country, the word desertification is generally used in a narrow sense, which usually refers to the environmental degradation process in which the land productivity in the original non-sandy desert area is reduced or lost due to strong man-made economic activities, drought, strong winds and other reasons, and is referred to as desertification for short.
Strange desert landscape
Deserts are often described as terrible. "Taklimakan" means "can't get in or out" in Uighur. In fact, there are some strange natural landscapes in the desert that are little known.
First of all, there is a mirage in the desert. This is mainly due to the hot sun shining on the sand surface, which makes the surface temperature suddenly rise and the density decrease. Air is not good at heat conduction, which makes the upper air temperature rise slowly and the air density is high. In this way, when light passes through two kinds of air with different densities, it is refracted and the distant scenery is displayed in front of us. This is a "mirage".
Secondly, the unique aeolian landforms include wind-eroded landforms (such as wind-eroded mushrooms, caves and niches, wind-eroded residual hills and castles, wind-eroded Ya Dan and Bailongdui, wind-eroded depressions and so on). ) and wind erosion landforms (such as crescent dunes and dune chains, compound crescent dunes and compound dune chains, parabolic dunes, grid dunes, crescent dunes and dunes, compound longitudinal dunes and pyramid dunes).
Thirdly, the strange phenomenon of "singing sand", also known as "singing sand", "magic sand", "singing sand", "gurgling sand" and "happy sand", is all kinds of wonderful sounds made by sand.
Fourth, the desert is indeed short of water, but it is not absolutely without water, and there may even be some scattered lakes. These freshwater lakes are not only extremely precious water resources, but also areas with relatively concentrated residents in the desert.
Fifth, there are oases in the desert. Deep in the oasis, there are often fruit trees in the forest, and thousands of trees are blooming, just like the "Peach Blossom Garden" in the desert.
The famous desert in the world
The total area of deserts in the world is about 6 million square kilometers, involving more than 30 countries and regions, the most famous of which are as follows.
The Sahara Desert is the "big brother" in desert in the world. It spans the whole of North Africa, covering an area of about 9 million square kilometers, almost equivalent to the entire land area of the United States, accounting for about 1/3 of the entire African area. Although the Sahara desert is vast, there are also many oases scattered with quicksand, which are home to more than 3 million people.
The Australian desert accounts for 44% of the total area of the Australian mainland, about 3.4 million square kilometers. Like the Sahara Desert, it is discontinuous in space, and its center is the Great Victoria Desert (647,000 square kilometers) across Western Australia and South Australia, the Dasha Desert in northern Western Australia (400,000 square kilometers), the Gibson Desert in Western Australia and the Simpson Desert in northern Australia (145,000 square kilometers). The driest part of the Australian desert also has an annual rainfall of 130mm, so it is not as cool and dry as the Sahara. Arabian Peninsula is the largest peninsula in the world, covering an area of 3 million square kilometers. More than half of its land is desert, which is one of the most concentrated areas in the world. Among them, the Rubhari Desert covers an area of 650,000 square kilometers, making it the second largest desert in the world after the Sahara Desert. One of the characteristics of the Arabian desert is that no permanent river originates from it or flows through its territory.
The Thar desert in the west of India and Pakistan, also known as the Indian Desert, covers an area of about 200,000 square kilometers and is located to the east of the Indus River. The humid air of the summer monsoon passes not far from its east, but not a drop of rain falls on this desert. The Indus Valley was the cradle of many splendid civilizations 4000-5000 years ago.
Although the Karakum Desert in Turkmenistan (350,000 square kilometers) and the Kizilkum Desert in Kazakhstan and Uzbekistan (300,000 square kilometers) are both large in absolute area, they are still small compared with the endless fertile grasslands around them. You can hardly engage in agriculture in this desert.
The North American desert is located in the western United States and the northwestern part of Mexico, and contains peculiar and diverse landforms. The desert can be roughly divided into four parts: Great Basin Desert (49.2 square kilometers), Mojave Desert (65,000 square kilometers), Sonoran Desert (3 1.000 square kilometers) and Chihuahua Desert (450,000 square kilometers). Among them, the great basin desert includes grassland, semi-desert and desert; Mojave desert is actually a small transition zone; Sonoran desert is the real desert texture. Chihuahua is a desert in the scientific sense.
The Atacama-Peru Desert in Chile and Peru in South America, though small in area, is the desert with the least rainfall in the world, with an average annual rainfall of less than 13mm.
China's famous desert.
China's desert covers an area of about 637,000 square kilometers, distributed between 75- 125 east longitude and 35-50 north latitude.
Taklimakan Desert is located between Tianshan Mountain, Kunlun Mountain, Altun Mountain and Pamir Plateau in Xinjiang, China, covering an area of about 337,600 square kilometers, and it is a big desert in China's national policy. The main natural characteristics of Taklimakan desert are: mobile sand dunes are the second largest mobile desert in the world; Dunes are high and complex in shape; Sandstorm is a serious hazard; Water resources are more abundant than other desert areas.
Gurbantunggut Desert is located in the middle of Junggar Basin, covering an area of about 50,000 square kilometers, and is the second largest desert in China. It consists of four deserts: in the west, the Bugle Desert in Bougourd; In the middle is the Dezosoten Ellison Desert, which is distributed to the south of Sanquan Valley. To the east, it is the Nerisin desert in the fire well; In the north of Sanquanzi dry valley, it is called Kuobu North-Akkum Desert. Among them, fixed and semi-fixed sand dunes account for 97% of the total desert area, which is the largest fixed and semi-fixed desert in China with relatively rich plant resources.
Badain Jaran Desert is located in the north of Heli Mountain and Longshou Mountain, east of Gulunai Lake on the east bank of weak water (downstream of Heihe River), west of Laishan Mountain in Ya Bu and south of Guaizi Lake, covering an area of 44,000 square kilometers. It is the third largest desert in China (according to some documents, it is also a desert dominated by mobile sand dunes. The remarkable difference between Badain Jaran Desert and other deserts in China is that there are many small inland lakes (Haizi) in the lowlands between tall sand mountains, with a total of 144.
Tengger Desert is located in the southeast of Alashan Plateau, between Helan Mountain and Laishan Mountain in Ya Bu, with an area of 36,700 square kilometers. It is the fourth largest desert in China. People used to think it was boundless quicksand, just like boundless sky. "Tian" is pronounced as "Tengger" in Mongolian, so it is called Tengger Desert. In fact, both the area and the height of sand dunes are not as good as the Badain Jaran Desert.
In addition, Mu Us Desert (meaning "bad water"), Horqin Sandy Land, Little Tengger Sandy Land, Kumtag Desert, Wulanbuhe Desert, Qaidam Basin Desert, Kubuqi Desert, Hulunbeier Sandy Land and Wuzhumuqin Sandy Land are also famous deserts in China.