Balochistan Plateau East of the Sulaiman and Kirthar ranges lies the Balochistan Plateau with an average altitude of 2,000 ft.(610 m). The physical features of the plateau are very varied, but mountains, plateaus and basins predominate the scene. The Mountains spread in various directions, attaining height 6,000- 11,000 ft. (1,830-3,335 m). In the north are the Toba Kakar Range and Chagai hills which form the border of Pakistan with Afghanistan for some distance. In the west-central part is the Siahan Range and in the east-southern corner the Mekran Range. Except for the Toba Kakar Range, which is dotted here and there with juniper, tamarisk and pistachio trees, all other ranges are naked and bleak. The mountains are carved off by innumerable channels and hill torrents which contain water only after rains. Very little water, however, reaches the basins lying on their foot. Comparatively more important rivers are Zhob, Bolan and Mulla, located in the north-eastern portion of Balochistan. The valleys of the main streams and their tributaries exhibit similar feature and consist of flat plains of alluvial soil in the centre, with a pebbly slope of varying length rising on either sides of the mountains. It is from these pebbly beds that the supply of water for irrigation is chiefly obtained through Karezes. Zhob, Bloan and their tributaries have formed two important alluvial basins of Balochistan, namely, the Lorlai basin and Quetta basin, which together produce a major portion of Balochistan's crops and fruits: wheat, barley, maize, lucerne, potato, apple, apricot, peach,almond, grape and pomegranate. Kalat Plateau at 7,000-8,000 ft. (2,135-2,440 m), in the centre of Balochistan is the most important plateau. The largest desert is found in western Balochistan. This is an area of inland drainage and dry lakes (hamuns), the largest of which is Hamun-i-Mashkhel, which is 54 miles long and 22 miles wide. The surface is littered with sun-cracked clay, oxidized pebbles, salty marshes and crescent-shaped movisng sand dunes. The area is known particularly for its constant mirage and sudden severe sand-storms. Being outside the sphere of monsoon current, Balochistan receives scanty and irregular rainfall (4 inches); the temperature is very high in summer and very low in winter. Owing to continuous draught, there is very little vegetation. Most of the people, therefore, lead nomadic life, raising camels, sheep and goats. Balochistan is, however, fortunate to have considerable mineral wealth of natural gas, coal, chromite, lead, sulphur and marble. The reserves of natural gas at Sui are among the largest in the world. The gas is piped to Karachi, Hyderabad, Sukkur, Multan, Faisalabad, Lahore, Rawalpindi and Quetta for use as industrial power.