THREE TYPES OF DESERTS(1) Tropical deserts (Hot deserts)(2) Temperate or Mid-latitude deserts(3) The Cold deserts

Principal hot deserts of the world North America: The Arizona and LowerCalifornia of the US and the Mexican desert. South America: Atacama Desert of north-ern Chile Africa: The Sahara, Kalahari and Namibdeserts Asia: The Arabian desert and the Thardesert of Pakistan and India, Taklamakan desertof China. Australia: Great Australian Desert

Deserts are areas of land that receive less than 250 mm (10 in) of rain peryear. About 12% of land is covered with desert.

IMPORTANT DESERTS OF THE WORLD

LARGEST DESERTSDESERTS AREA

(sq.km.) (sq. miles)

Sahara 86,60,000 33,20,000Arabian 23,30,000 9,00,000Gobi 12,00,000 4,63,000Patagonian 6,73,000 2,60,000Great Victoria 6,47,000 2,50,000Great Basin 4,96,000 1,90,000Chihuahuan (Mexico) 4,50,000 1,74,000Great Sandy 4,07,000 1,57,000Kara Kum 3,50,000 1,35,000Sonaran 3,10,000 1,20,000

SOUTHAMERICA

NORTHAMERICA

North AmericanDesert

Atacama Desert

EUROPE

AFRICA

Sahara Desert

Kalahari Desert

GreatAustralian

Desert

AUSTRALIA

ASIA

TharDesert

TurkestanDesert

TaklamakanDesert

Gobi Desert

ArabianDesert

Patagonian Desert

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DESERTS

Taklamakan desert is the largest desert in China;it is in Sikiang Province.

Gibson, Simpson, Victorian and Great Sandydesert are together called as Great AustralianDesert.

Kalahari desert is an inland basin with annualrainfall averaging less than 50 cm. Aborigines of Kalahari desert is called Bush-men, have perfected unique methods to survivein desert like condition. It is situated between the Orange river andZambezi river. Most of the Kalahari lies in Botswana.

Atacama desert in northern Chile has almost novegetation and is considered as the world’s dri-est desert. Atacama is rich in nitrates (caliche), iodineand borax.

The hottest place in the world is Al-Azizhiya,(Libya) is in the Sahara desert.

The Arabian desert and the Thar desert of Indiaand Pakistan are tropical deserts.

The Thar (or the Great Indian desert) desert be-gins roughly from the southern edge of thePunjab and continues through North-WesternRajasthan upto the Aravalli Range.

? Find the odd man out(a) Taklamakan desert (b) Gobi desert(c) Arabian desert (d) Thar desertAns: (d) Gobi desert Among them Gobi desert is the only cold desert.

Gobi desert is the coldest desert in the world. Itspreads over Mongolia and China.

Much of the Gobi desert is devoid of vegetationare practically uninhabited.

The main difference between temperate desertsand the tropical deserts is that the temperatedeserts are below freezing point for many monthsof the cold season.

DESERT RECORDS The largest desert in the World: Sahara desert.

Its spreads over nearly 6% of world’s totalland area and 28% of the land area of Africa.

The highest temperatures in the world are re-corded in hot deserts.

? The highest temperature in the world has beenrecorded at(a) Death Valley (b) Al-Aziziyah(c) Jacobabad (d) IqiqueAns: (b) Al-Aziziyah

Al-Aziziyah in the northern coast of Africandesert has been recorded a temperature of 58.70C.

Death Valley of USA (the highest temperaturerecorded in USA) has recorded 58.40C. Averagerainfall in Death Valley is 38mm per year.

Jacobabad in the Thar desert section of Paki-stan has recorded temperature of 51.70C.

Driest place on earth is Iqique, Atacama desert. Coldest desert in the world: Gobi desert.

DESERT FEATURESWeathering caused by strong winds, huge tem-

perature variations between day and night, and oc-casional fast flowing water, forms distinctive desertfeatures.

Wadis: Desert water courses which aresteep sided with a flat floor. They are usuallydry. Barkhans: Crescent shaped dunes with twohorns may grow up to 30m (100 ft) high. Barkhansare always moving. Seifs Dunes: They are long ridges of sandthat occur where there is little sand and a pow-erful wind. They grow up to 215 m (700 ft) high. Zeugen: They are parallel, flat topped ridgeswith caps of hard, resistant rock perched onsofter rock below. Mirages: They occur when a layer of warmair next to the ground is trapped by cooler airabove. Light bends towards the horizontal line ofvision and eventually travels upwards. The mirage is an upside down virtual im-age.

OASIS A fertile patch in an arid (dry) area where wa-

ter is available. Livestock is limited in the oasis but most of

the land is under cultivation. Water buffalo,

oxen, donkeys and camels are used asdrought animals and to work the water wheel.

The houses in the oasis are simple and wellsuited to the climate. They are made of sun-dried bricks made with straw mixed with clayto give more strength to the bricks.

DESERT VEGETATION Desert and semi desert vegetation is found in

regions where the rainfall is less than 25 cm andwith an average rainfall temperature of 250–270C.

The vegetation mostly consists of thornybushes, acacias, wild berries and babul and kikar.In India these are found in Rajasthan, Kutchand Saurashtra in Gujarat, South-WesternPunjab and parts of the Deccan.

The largest cactus is the giant Saguaro fromthe Sonaran desert (Mexico). It can grow to 18 m(60 ft) high.

The Sonaran desert of Mexico is noted forits fleshy and thorny plants such as giantSaguaro, Cholla and other varities of cacti andyuccas.

The ‘cactus’ has small roots but it sucks waterin great quantities and stores it in its thick body.

GONE WITH THE WIND Harmattan: It is a hot dry, dust laden windblowing from Sahara to the Guinea cost. Alsocalled the doctor, it provide a welcome relief fromdamp air of the Guinea lands by increasing therate of evaporation with resultant cooling ef-fects.

Sirocco: A hot local wind blowing fromSahara desert to Mediterranean.

The Sirocco winds in Libya is known asGibli.

Khamsin: Hot, dry and dusty winds whichblow across Egypt from April to May.

Loo: In the plains of northern India and Pa-kistan sometimes a very hot and dry wind blowsfrom the west in the months of May and June,usually in afternoon.

Its temperature unvariably ranges between450C and 500C. It may cause sunstroke to people.

FARMING IN HOT DESERTS In summer rice, millet, maize are the main grain

crops. Small quantities of sugarcane and cottonare also grown.

In winter the same lands are used for growingcrops of wheat, barley, oil seeds, onion andbeans.

The date palm (Phoenix ductylifera) is the old-est known cultivated fruit tree in the desert.

The young palm needs to be watered for acouple of years.

DESERT SOILS Desert soils are those soils which have turned

into sand due to excessive weathering, evapo-ration and lack of moisture. Strong winds shiftlarge arid dunes from one place to another.

If there is some availability of water in the desertsoil, millets are grown there.

The desert soil is fertile and the hot sun causesquick growth and ripening.

MINERALS OF DESERTS The deserts have become prominent because of

the valuable minerals they yield. The Kalahari desert yields copper and dia-monds.

Desert farm, using plastic to slow evaporationin the San Quintin Valley, Mexico

DESERT FOXErwin Rommel (1891-1944) German Field Mar-shal, renowned for his Af-rican desert victories dur-ing World War II. His vic-tories earned him promo-tion to Field Marshal aswel l as the n ickname “The Desert Fox”.

as Bedouins (the dweller of the deserts). They are also nomads living in tents andmoving from well to well and pasture to pasture.

The Bushmen of the Kalahari desert lead a no-madic life and are still at a very primitive stage ofdevelopment. They can imitate the calls of every wild ani-mals they know.

The Bindibus of the Australian deserts are someof the most backward people in the world. They know only a few implements like diggingsticks, grinding stones, spears and boomerang. Bindibus train young dingo dogs to trackand run down kangaroos and rabbits.

URBAN CENTERS OFDESERT AREA

Cairo, Alexandria, Said and Suez are the impor-tant urban centers of Africa.

Baghdad (capital of Iraq), Basra, Aden (Key tothe Suez), Mecca, Karachi are the important cen-ters of Asia.

Inqique (Chile), Tocopilla, Lima (Peru) of SouthAmerica.

Phoenix and Diego are in North America. Egypt lies within the North African desert belt.

The climate is warm and sunny through out theyear.

GREAT DESERTSName Country/Region

Sahara North AfricaAustralian Desert Australia

Arabian Desert ArabiaDast-e-Lut Iran

Dast-e-Kavir IranDesierto de Sechura Peru

Atacama North ChilePatagonia Argentina

Kalahari BotswanaNamib Namibia

Thar North-west IndiaNegev IsraelOrdos China

Takla Makan ChinaGobi Mongolia, China

Kara Kum TurkmenistanKyzyl Kum Kazhakhstan,

UzbekistanMohave South California,

North AmericaSonoran North America,

Mexico* * *

Kara Kum and Kyzyl Kum together are known asthe Turkestan desert

***Rub’al Khali & An-Nafud together called

Arabian desert***

Dast-e-Kavir and Dast-e-Lut are otherwise calledBarren Desert and Salt Desert respectively.

The North American desert has silver, lead,copper, borax, gold and petroleum. The Australian desert yields gold inKalgoorlie and Coolgradie area. The Atacama desert yields copper and theChilean part of it has the world-famous depositsof nitrates. Chiquicamata in the Atacama desert lies theworld’s largest copper mine at a height of 3,000metres in the deserts. In Africa, the main oil producing regions inthe Saharan deserts are Egypt and Libya.

ETHNIC GROUPS The principle ethnic groups of the Sahara are

the Turaregs. The Turaregs of the western Sahara desertare mostly nomadic. They build huts of driedgrass (called zeribar) during hot weather andbuild leather tents during cooler weather.

The inhabitants of the Arabian desert are known

THE SHIP OF THE DESERT Camel is the dependable means of travel in

the desert and has been optly called ‘Theship of the desert’.

It can travel 160 km (100 miles) a day and for8 days without drinking water.

It has very tough lips and tongue which en-able it to nibble at thorny desert vegetation.

It has broad feet and tough skin to protectthe soles of its feet.

It can move easily upon the difficult desertsurfaces of gravel, stone, sand and rock.