. The story of Africa and its explorers. it is seldom that a aacU sunk fora fcAv feet in one of the holloAvs does notreach a small accumulation of Avater. Thisdreaded country of sand-hills is knoAvn to theArabs as the Erg, or On the other side of it is the lofty plateauof Ahaggar, Avhich constitutes the middle partof the Soudan, and, so far fromcarrying out the popular notion ^^^ ^^t^of the Sahara, rises to an averageheio-ht of 4,000 feet, Avhere the Avinters areso severe that for three months at a timesnow Avhitens the surfaces of this portion ofthe desert. From this section the countr
. The story of Africa and its explorers. it is seldom that a aacU sunk fora fcAv feet in one of the holloAvs does notreach a small accumulation of Avater. Thisdreaded country of sand-hills is knoAvn to theArabs as the Erg, or On the other side of it is the lofty plateauof Ahaggar, Avhich constitutes the middle partof the Soudan, and, so far fromcarrying out the popular notion ^^^ ^^t^of the Sahara, rises to an averageheio-ht of 4,000 feet, Avhere the Avinters areso severe that for three months at a timesnow Avhitens the surfaces of this portion ofthe desert. From this section the country 80 THE STOBY OF AFRICA. falls gently towards the basin of the Nigerand Lake Tchad, though Mount Tusside, inthe Tibboo country, attains a height of8,000 feet, and the oasis of Air, or Asben, isin reality a clump of hills which, in oneplace at least, attain a height of 6,500 feet. These hilly portions of the Soudan arehollowed into many deep vaUeys, seamedwith the dry beds, or wadys, of ancientrivers, which, though empty for the greater. ARAB TRIBESMAN. part of the year, and sometimes for yearstogether, will occasionally after heaA^y rains orthe melting of the upland snows course in afoamino current towards the shotts, or saltlakes without outlet, which form so remark-able a feature in the geography of Tunisiaand the neighbouring region. Even the Draa,except when the Atlas snows are melting,seldom sends its waters to the sea. Thesevalleys are nearly all inhabited, for if wateris not found on the surface or in the water-courses, enough can easily be obtained forthe sheep, cattle, camels, and horses of thewandering tribesmen by sinking shallow wells. The Hamada is another variety of Sa-haran surface. It consists of low plateaux,strewn with blocks of granite andother rocks, alternating with tracts ada or eie- marshes yated stonytracts. of bare sand, broadcovered with thin layers of salt, orof flats littered with small rounded Hamadas are invariably barren, and,unless
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Keywords: ., bookcentury1800, bookdecade1890, bookpublisherlondo, bookyear1892
