Deserts from the World General Knowledge

Deserts from the World General Knowledge

SAHARA

The Sahara is technically the world’s second largest desert after Antarctica. At over 9,000,000 square kilometres (3,500,000 sq mi), it covers most parts of northern Africa; an area stretching from the Red sea, including parts of the Mediterranean coasts, to the outskirts of the Atlantic ocean. It is almost as large as the United States, and is larger than Australia. Its name derives from an Arabic word meaning “desert”: “ṣaḥrā´” (صحراء); to refer to the Sahara as the ‘Sahara Desert’ is therefore a pleonasm.

The Sahara desert covers huge parts of Algeria, Burkina Faso, Chad, Egypt, Libya, Mali, Mauritania, Morocco, Niger, Senegal, Sudan and Tunisia.

The Sahara includes many landforms such as rivers (Nile River, Sénégal River), mountain ranges (Aïr Mountains, Ahaggar Mountains, Saharan Atlas, Tibesti Mountains), smaller deserts and ergs (Libyan Desert, Ténéré, Egyptian Sand Sea, Qattara Depression, Erg of Bilma, Erg Chebbi), lakes (Lake Chad) and oases (Bahariya, Ghardaïa, Timimoun).

According to a botanical criteria of Cap-Rey, the Sahara is comprised between the following:

* at north: limits of the maturity of Phoenix dactylifera (date palm trees)

* at south: southern limit of Cornucala monacantha (a Chenopodiaceae) or northern limit of the Cencrus biflorus (a Poaceae of the Sahel region).

The Sahara has one of the harshest climates in the world. It has many strong winds that blow from the north-east. Sometimes on the border zones of the north and south, the desert will receive about 25 cm (10 in.) of rain a year. The rainfall happens 

GOBI

The Gobi is a large desert region in China and southern Mongolia. The desert basins of the Gobi are bounded by the Altay Mountains and the grasslands and steppes of Mongolia on the north, by the Tibetan Plateau to the southwest, and by the North China Plain to the southeast. The Gobi is made up of several distinct ecological and geographic regions, based on variations in climate and topography. This desert is both Asia’s largest and the fourth largest in the world.

The Gobi is most notable in history as part of the great Mongol Empire, and as the location of several important cities along the Silk Road.

The Gobi is a rain shadow desert formed by the Himalaya range blocking rain-carrying clouds from reaching the Gobi.

The Gobi measures over 1500 kilometers from southwest to northeast and 800 km from north to south. The desert is widest in the west, along the line joining the Baghrash Kol and the Lop Nor (87°-89° east). It occupies an arc of land 1,295,000 square kilometers (500,000 mi²) in area, making it fourth largest in the world and Asia’s largest. Much of the Gobi is not sandy but is covered with bare rock.

The Gobi desert is a cold desert, and it is not uncommon to see frost and occasionally snow on its dunes. Besides being quite far north, it is also roughly 900 meters (2,953 ft) above sea level, which further contributes to its low temperatures. An average of approximately 194 millimeters (7.6 in) of rain falls per year in the Gobi. Additional moisture reaches parts of the Gobi in winter as snow is blown by the wind from the Siberian Steppes. These winds cause the Gobi to reach extremes of temperature like no other, ranging from –40°C in Winter to +50°C in Summe

ARABIAN DESERT

The Arabian Desert is a vast desert wilderness stretching from Yemen to the Persian Gulf and Oman to Jordan and Iraq. It occupies most of the Arabian Peninsula with an area of 2,330,000 square kilometers (900,000 mi²). At its center is the Rub’al-Khali, one of the largest continuous bodies of sand in the world. Gazelles, oryx, sand cats, and spiny-tailed lizards are just some of the desert-adapted species that survive in this extreme environment, which features everything from red dunes to deadly quicksand. The climate is extremely dry, and temperatures oscillate between extreme heat and seasonal nighttime freezes. It is part of the Deserts and xeric shrublands biome and the Palearctic ecozone.

This ecoregion holds little biodiversity, although a few endemic plants grow here. Many species, such as the striped hyena, jackal and honey badger have become extinct in this area due to hunting, human encroachment and habitat destruction. Other species have been successfully re-introduced, such as the endangered white oryx and the 

TAKLAMAKAN

The Taklamakan Desert (also Taklimakan) is a desert of Central Asia, in the Xinjiang Uyghur Autonomous Region of the People’s Republic of China. It is known as one of the largest sandy deserts in the world. It covers an area of 270,000 km² of the Tarim Basin, 1,000 km long and 400 km wide. It is crossed at its northern and at its southern edge by two branches of the Silk Road as travellers sought to avoid the arid wasteland.

There is no water on the desert and it was hazardous to cross. Merchant caravans on the Silk Road would stop for relief at the thriving oasis towns. The key oasis towns, watered by rainfall from the mountains, were Kashgar, Marin, Niya, Yarkand, and Khotan (Hetian) to the south, Kuqa and Turfan in the north, and Loulan and Dunhuang in the east. Now some, such as Marin, are ruined cities in a sparsely inhabited dusty spot with poor roads and minimal transportation in the Xinjiang Autonomous Region of the Peoples Republic of China.

The White Jade River flows into the Taklamakan, as do the Yarkant He originating in the Kunlun Mountains and the river from the Tien Shan range.

Mummies, some 4000 years old, have been found in the region. They show the wide range of peoples who have passed through. Some of the mummies appear European. Later, the Taklamakan was inhabited by Turkic peoples. Starting with the Tang Dynasty, the Chinese periodically extended their control to the oasis cities of the Taklamakan in order to control the important silk route trade across Central Asia. Periods of Chinese rule were interspersed with rule by Turkic and Mongol and Tibetan peoples. The present population consists largely of Turkic Uyghur and Kazakh people in the countryside, while the population of the larger cities is predominantly Han Chinese.

KALAHARI

The Kalahari Desert is a large arid to semi-arid sandy area in southern Kgalagadi Africa extending 900,000 km² (362,500 sq. mi.), covering much of Botswana and parts of Namibia and South Africa, as semi-desert, with huge tracts of excellent grazing after good rains. The Kalahari Desert is in Africa at the southern part and the desert is a portion of desert and a plateau. The Kalahari supports some animals and plants because most of it is not true desert. There are small amounts of rainfall and the summer temperature is very high. It usually receives 5-10 inches of rain per year. The surrounding Kalahari Basin covers over 2.5 million km² extending farther into Botswana, Namibia and South Africa, and encroaching into parts of Angola, Zambia and Zimbabwe. The only permanent river, the Okavango, flows into a delta in the northwest, forming marshes that are rich in wildlife. Ancient dry riverbeds—called omuramba—traverse the Central Northern reaches of the Kalahari and provide standing pools of water during the rainy season. Previously havens for wild animals from elephant to giraffe, and for predators such as lion and cheetah, the riverbeds are now mostly grazing spots, though leopard or cheetah can still be found.

THAR

The Thar Desert (Hindi: थार मरुस्थल) , also known as the Great Indian Desert, is a desert located in western India and southeastern Pakistan. It lies mostly in the Indian state of Rajasthan, and extends into the southern portion of Haryana and Punjab states and into northern Gujarat state. In Pakistan, the desert covers eastern Sind province and the southeastern portion of Pakistan’s Punjab province. In Pakistan’s Punjab province it is known as the Cholistan Desert. Tharparker District of province Sindh Pakistan is also a part of Thar desert. The Thar Desert is bounded on the northwest by the Sutlej River, on the east by the Aravalli Range, on the south by the salt marsh known as the Rann of Kutch (parts of which are sometimes included in the Thar), and on the west by the Indus River. Its boundary to the large thorny steppe to the north is ill-defined. Depending on what areas are included or excluded, the nominal size of the Thar can vary significantly.

According to the WWF definition, the desert proper has 92,200 square miles (238,700 km²). Another source gives the area of the Thar Desert as 446,000 km² extending 805 km (about 500 mi) long and about 485 km (about 300 mi) wide, with 208,110 square kilometres in India. Of the Indian portion, 61% falls in Rajasthan, 20% in Gujarat and 9% in Punjab and Haryana combined. The greater portion lies in Rajasthan, covering about three-fifths of the total geographical area.

The origin of the Thar Desert is a controversial subject. Some consider it to be 4000 to 10,000 years old, whereas others state that aridity started in this region much earlier. Another theory states that area turned to desert relatively recently: perhaps around 2000 - 1500 BCE. Around this time the Ghaggar ceased to be a major river. It now terminates in the desert. It has been observed through remote sensing techniques that Late Quaternary climatic changes and neotectonics have played a significant role in modifying the drainage courses in this part and a large number of palaeochannels exist.

Most of the studies share the opinion that the palaeochannels of the Sarasvati coincide with the bed of present day Ghaggar and believe that the Sutlej along with the Yamuna once flowed into the present Ghaggar riverbed. It has been postulated that the Sutlej was the main tributary of the Ghaggar and that subsequently the tectonic movements might have forced the Sutlej westwards, the Yamuna eastwards and thus dried up the Ghaggar.

ATACAMA

The Atacama Desert is a virtually rainless plateau in South America, extending 966 km (600 mi) between the Andes mountains and the Pacific Ocean. It is created by the rain shadow of the Andes east of the desert. Its area is 181,300 square kilometers (70,000 mi²), mostly in Chile, but parts in Peru, Bolivia and Argentina. It is made up of salt basins (salares), sand and lava flows, and is 15 million years old and 100 times more arid than California’s Death Valley.

The Atacama Desert is the driest place on Earth, and is virtually sterile because it is blocked from moisture on both sides by the Andes mountains and by coastal mountains. The average rainfall in the Chilean region of Antofagasta is just 1 mm per year, and at one time no rain fell in the entire desert for 400 years. Some weather stations in the Atacama have never received rain. Evidence suggests that the Atacama may not have had any significant rainfall from 1570 to 1971. It is so arid that mountains that reach as high as 6,885 metres (22,590 feet) are completely free of glaciers and, in the southern part from 25°S to 27°S, may have been glacier-free throughout the Quaternary — though permafrost extends down to an altitude of 4,400 metres and is continuous above 5,600 metres. Studies by a group of British scientists have suggested that some river beds have been dry for 120,000 years.

Some locations in the Atacama do receive a marine fog known locally as the Camanchaca, providing sufficient moisture for hypolithic algae, lichens and even some cacti. But in the region that is in the “fog shadow” of the high coastal crest-line, which averages 3,000 m height for about 100 km south of Antofagasta, the soil has been compared to that of Mars. Due to its otherworldly appearance, the Atacama has been used as a location for filming Mars scenes, most notably in the television series Space Odyssey: Voyage to the Planets.

In 2003, a team of researchers published a report in Science magazine titled “Mars-like Soils in the Atacama Desert, Chile, and the Dry Limit of Microbial Life” in which they duplicated the tests used by the Viking 1 and Viking 2 Mars landers to detect life, and were unable to detect any signs in Atacama Desert soil. The region may be unique on Earth in this regard and is being used by NASA to test instruments for future Mars missions. Alonso de Ercilla characterized it in La Araucana, published in 1569: “Towards Atacama, near the deserted coast, you see a land without men, where there is not a bird, not a beast, nor a tree, nor any vegetation”.