Geography Group Work

Roll No. = 26-30

Introduction• It is the world's 18th largest subtropical desert.

• 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 BC.

• Most studies did not share the opinion that the

palaeochannels of the Sarasvati River coincide with the bed of

the present-day Ghaggar and believe that the Sutlej along

with the Yamuna once flowed into the present 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-Hakra.

• Studies on Kalibangan in the desert region by Robert

Raikes indicate that it was abandoned because the river dried up.

Location and Description

•The Thar Desert also known as the Great Indian

Desert is a large, arid region in the northwestern part

of the Indian subcontinent and forms a natural

boundary running along the border between India and

Pakistan.

•Thar Desert extends from the Sutlej River ,

surrounded by the Aravalli Ranges on the east, on the

south by the salt marsh known as the Great Rann of

Kutch (parts of which are sometimes included in the

Thar), and on the west by the Indus River.

• With an area of more than 200,000 km2 (77,000 sq mi), within the Indian state of Rajasthan, covering the districts of Jaisalmer, Barmer, Bikaner and Jodhpur, and some region of the states of Punjab, Haryana and Gujarat.

• In Pakistan, the desert covers eastern Sindh Province and the southeastern portion of Punjab Province, where it joins the Cholistan Desert near Bahawalpur. The Tharparkar District is one of the major parts of the desert area. Tharparkar consists of two words: Thar means 'desert' while Parkar stands for 'the other side'.

Location

Weather Conditions• The amount of annual rainfall in the desert is generally

low, ranging from about 4 inches (100 mm) or less in the west to about 20 inches (500 mm) in the east. Precipitation amounts fluctuate widely from year to year. About 90 percent of the total annual rainfall occurs during the season of the southwest monsoon, from July to September. During other seasons the prevailing wind blows from the northeast. May and June are the hottest months of the year, with temperatures rising to 122 °F (50 °C). During January, the coldest month, the mean minimum temperature ranges between 41 and 50 °F (5 and 10 °C), and frost is frequent. Dust storms and dust-raising winds, often blowing with velocities of 87 to 93 miles (140 to 150 km) per hour, are common in May and June.

Physiography and Geology• The desert sands cover Archean (early

Precambrian) gneiss (metamorphic rocks formed more than 2.5 billion years ago), Proterozoic (later Precambrian) sedimentary rocks (about 540 million to 2.5 billion years old), and more recent alluvium (material deposited by rivers). The surface sand is aeolian (wind-deposited) sand that has accumulated over the last 1.8 million years.

• The desert presents an undulating surface, with high and low sand dunes separated by sandy plains and low barren hills, or bhakars, which rise abruptly from the surrounding plains. The dunes are in continual motion and take on varying shapes and sizes. Older dunes, however, are in a semistabilized or stabilized condition, and many rise to a height of almost 500 feet (150 metres). Several playas (saline lake beds), locally known as dhands, are scattered throughout the region.

• The soils consist of seven main groups—desert soils, red desertic soils, sierozems (brownish gray soils), the red and yellow soils of the foothills, the saline soils of the depressions, and the lithosols (shallow, weathered soils) and regosols (soft, loose soils) found in the hills. All these soils are predominantly coarse-textured, well-drained, and calcareous (calcium-bearing). A thick accumulation of lime often occurs at varying depths. The soils are generally infertile and, because of severe wind erosion, are overblown with sand.

Wildlife• Stretches of sand in the desert are

interspersed by hillocks and sandy and gravel plains. Due to the diversified habitat and ecosystem, the vegetation, human culture and animal life in this arid region is very rich in contrast to the other deserts of the world. About 23 species of lizard and 25 species of snakes are found here and several of them are endemic to the region.

• Some wildlife species, which are fast vanishing in other parts of India, are found in the desert in large numbers such as the blackbuck (Antilope cervicapra), chinkara (Gazella bennettii) and Indian wild ass (Equus hemionus khur) in the Rann of Kutch. They have evolved excellent survival strategies, their size is smaller than other similar animals living in different conditions, and they are mainly nocturnal.Other mammals of the Thar area include a subspecies of red fox (Vulpes vulpes pusilla) and a wild cat, the caracal.

Natural

Vegetation• The natural vegetation of this dry area is classed as Northern Desert Thorn Forest occurring in small clumps scattered more or less openly. Density and size of patches increase from west to east following the increase in rainfall. Natural vegetation of Thar Desert is composed of tree, shrub and herb species.

• Small trees and shrubs:-Calligonum polygonoides, Acacia jacquemontii, Ziziphus zizyphus, Ziziphus nummularia, Calotropis procera, Aerva javanica, Euphorbia neriifolia, Cordia sinensis,Maytenus emarginata, Capparis decidua.

• Herbs and Grasses:-Ochthochloa compressa, Lasiurus scindicus, Panicum antidotale, Cenchrus ciliaris, Desmostachya bipinnata, Ergamopagan species, Phragmites species, Typha species, Sorghum halepense, Citrullus colocynthis.

Efforts By:-•Muskaan Chhonker

•Muskan Tanwar

•Pushpanjali

•Poornima

•Reet Mensharamani

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