What are the causes of desert formation? How are deserts formed? What are the main reasons?

Genesis. Desertification can be understood as a kind of desertification, that is, after the destruction of vegetation, the ground loses its cover, and the desert gradually turns into a desert-like landscape under the action of arid climate and strong winds. Land desertification occurs mainly in arid and semi-arid areas.

The key factor in the formation of the desert is the climate, but in the edge of the desert, the native vegetation may be grassland, which is desertified due to human reasons, and these human factors are mainly the following:

l) Unreasonable farming. Whether in desert areas or native grassland areas, once reclaimed, the land will be desertified. From 1958 to 1962, a one-sided understanding of large-scale agriculture was carried out, and in pastoral areas, semi-agricultural and pastoral areas, and agricultural areas were indiscriminately cultivated, and in 1966 and 1973, a one-sided emphasis was placed on grain as the key link, saying that "herdsmen do not suffer from the loss of grain." As a result, the phenomenon of indiscriminate reclamation of pastures appeared in pastoral areas, resulting in the rapid development of desertification of pastures.

Due to the serious wind erosion, after the reclamation of the desert area, the yield can still maintain twenty or thirty kilograms in the first two years, and it is difficult to recover even the seeds later, so it is only to abandon the cultivation and open up a new piece of land, which leads to "one acre of wasteland and three acres of desertification". According to statistics, 1.2 million hectares of grassland have been reclaimed in Ordos alone, resulting in 1.2 million hectares of grassland desertification to varying degrees.

2) Overgrazing. Due to the overabundance of livestock, the grassland grass production is insufficient, so that many high-quality grass species cannot grow.

Desert seeds or seeds are eaten when they are ripe. In addition, like goats, which account for more than half of the total number of livestock, they are very fast, good at stripping the stems and bark of sandy shrubs, gouging grass roots, and trampling, so that the grassland produces less and less grass, forming desertified land, causing a vicious circle.

3) Unreasonable woodpicking. Historically, wood mining has been one of the important factors responsible for the formation of quicksand in irrigated oases and dryland agricultural areas in China. For example, it is estimated that a family of five needs more than 700 kilograms of firewood per year, and each household needs 5,000 kilograms if Artemisia is extracted, which is equivalent to most or all of the Artemisia oleifera produced by more than 3 hectares of fixed and semi-fixed sand dunes.

According to statistics, 200,000 hectares of Bala grassland has been desertified by Yikezhao League alone.

1.It is located deep inland, with little precipitation. Such as the Central Asian region.

2.Blocked by the mountains, it is located on the leeward slope of the mountains. Such as the Patagonian plateau in southern South America.

3.It is cooled and dehumidified by the cold snap. Such as the desert off the coast of Peru.

4.Perennial subtropical high pressure or trade winds from the inland. Such as the Sahara Desert.

5.Caused by man-made destruction of vegetation in arid areas. Such as some areas in the northwest of our country.

Many deserts are the result of a combination of factors.

How did the Sahara Desert form?

1. Seawater flushing and erosion: formed by the erosion of seawater on rocks on land. The more water-soluble components of the rock, such as limestone, are lost with the seawater, and the sand is very hard, the quartz will be retained slowly, and the large pieces of quartz will gradually break into small pieces over time due to the impact and weathering of the seawater, until they become small grains of sand.

2. Rivers on land carry large amounts of sediment into the sea.

After the weathering of the rock, it is carried by the transportation of wind or water flow, the small mass is taken away and deposited to form the soil - plain, the medium quality is taken away when the wind speed or flow speed decreases and the sediment is formed to form a beach (the soil is carried farther away when the carrier speed decreases, and the broken stone is deposited in advance), and the large mass remains in place to continue weathering. In the end, it turned into soil, and that's how the soil on Earth is now formed. Of course, there is also the phenomenon of magma erupting into rocks, although there are far fewer volcanoes today than in ancient times.

The sand used now is brought from the sand field, where the sand gathers.

The main component of sand is silica.

One of the conditions for the formation of deserts is an arid climate. When you open the world map, you will see that most of the deserts are between the Tropic of Cancer and the Tropic of Capricorn.

The location between the Tropic of Capricorn and the Tropic of Capricorn is where the sun can directly reach during the year, so the desert is hotter than other places. When the temperature is high, the water in the soil evaporates more quickly and eventually gradually turns into dry sand.

In addition to this, the scarcity of precipitation is also the main reason for the formation of deserts. According to scientists, the annual precipitation in desert areas is generally less than 50 mm, and in some places there is not even a drop of rain all year round.

These areas, which are not nourished by rain, are scorched by the sun all day long, and slowly turn into deserts. When we see the desert on TV, we can't help but marvel at the grandeur that stretches as far as the eye can see.

This is thanks to the wind that carries the sand. The wind in the desert area is very strong, and after blowing away the sediment on the ground, when the wind weakens or encounters obstacles, many sand dunes are piled up, covering the ground and eventually forming a desert. As a result, the surface of the desert changes its shape in response to the wind.