How did the Sahara come into being?

Reasons for the formation of the Sahara desert:

1. North Africa lies on both sides of the Tropic of Cancer. Controlled by subtropical high pressure belt all the year round, dry and hot downdraft prevails. The African continent is narrow in the south and wide in the north, controlled by the subtropical high zone, with a wide dry-hot area.

2. North Africa is adjacent to the Asian continent, and the northeast trade wind blows from the eastern land, making it difficult to form precipitation and making North Africa drier.

3. The coastline of North Africa is straight, and there is an Ethiopian plateau in the east, which acts as a barrier to the humid airflow, so that the vast inland areas are not affected by the ocean.

4. There is a canary cold current passing through the west coast of North Africa, which plays a role in cooling and dehumidifying the western coastal areas and makes the desert approach the west coast.

In the last ice age, the Sahara was not a desert, and the climate was similar to that of East Africa. About 30,000 ancient rock paintings were found in the desert, about half of which were on Acer Plateau in southern Algeria, depicting animals in rivers, such as crocodiles.

At the same time, dinosaur fossils were also found. But since 3000 BC, there has been almost no large area of vegetation in the Sahara except the Nile Valley and oases scattered in the desert.

Extended data:

The climate in the Sahara desert is hot and dry. However, it is puzzling that there was a prosperous ancient civilization in this extremely arid and water-deficient mining area with cracked land and few plants. Many exquisite large-scale murals in the desert are the crystallization of this ancient civilization.

Although the Sahara desert (excluding the Nile Valley) is as big as the United States, its residents are estimated to be only 2.5 million, less than 0.4 people per square kilometer. The vast territory is empty, but as long as barren vegetation can feed livestock or have reliable water sources, scattered people will survive in the most difficult environment and precarious ecological environment in the world.

Tropical animals in the northern Sahara desert include tropical catfish and reindeer, both of which live in isolated oases in Bisquerra and Sahara desert. Cobras and crocodiles may still live in the river basins of the distant Tibesti Mountains.

Mammals in the Sahara desert include gerbils, jerboa, rabbits and desert hedgehogs. Berberi sheep and sickle antelope, Dogas antelope, Dama deer and Nubian wild donkey; Anubis baboons, hyenas, wolves and sand foxes; Libyan white-necked ferrets and slender mongooses.

There are more than 300 species of birds in the Sahara desert, including non-migratory birds and migratory birds. Coastal areas and inland waterways attract many kinds of waterfowl and shorebirds. There are ostriches, all kinds of captive birds, herons, pheasants and Nubian bustards, desert owls, barn owls, sand larks and gray swallows, and ravens with brown necks and fan-shaped tails.

Frogs, toads and crocodiles live in lakes and swamps in the Sahara desert. Lizards, refugees, skinheads and cobras haunt rocks and bunkers. There are algae, saltwater shrimp and other crustaceans in lakes and ponds in the Sahara desert. Snails living in the desert are an important food source for birds and animals. Desert snails survived their summer sleep and were inactive for several years before being awakened by rain.

Baidu Encyclopedia-Sahara Desert