Page:Africa by Élisée Reclus, Volume 2.djvu/516

 424 NORTH-WEST AFRICA. tinued towards the north-west by a low ridge separating the Nile basin from the waters flowing in the direction of Lake Tsad. Here begins the line of hills and plateaux which crosses the desert obliquely for a distance of about 1,200 miles, as far as the Twat oases and the Wed Saura. A first group of rocks and hills constitutes the land of Ennedi, known also by other names to the Arab and native travellers. Its valleys, which give rise to a few wadics, are inhabited by members of the formerly powerful Zoghawa nation, who also roam the stepjKJS of North Dar-For, and who in the twelfth century ruled over the whole region comprised between the Nile Valley and the highway from Fezzan to Bornu. A few thousands of the Dar-For Baele or Bideyat people also occupy several of the Ennedi valleys, where some Tibbu tribes from the north-west are tolerated by the rulers of the land. But no European traveller has yet pMie- trated to Ennedi, which is known only from the reports of native traders. North-westwards the line of uplands is prolonged in the direction of the axis of the Sahara, enclosing the Wajanga (Wanjanga, Wanja, Onja) oasis, which has also not yet been visited by any European explorer. It is known from the accounts of traders that the surrounding hills are quarried for the rock-salt contained in them. From the Wajanga oasis the tableland slopes gently northwards in the direction of the palm groves of Kufra. TlBESTl — BORKU. The range of mountains known to the natives by the name of Tu, that is, the " Rocks," and usually called Tibesti by the Arab travellers, to the inhabitants of the southern plains of Borku presents the appearance of a regular rocky cliff bounding the northern horizon. This range, which is about 300 miles long, or 420 including its less elevated offshoots, was known only by name till the year 1869, when Nachtigal undertook a dangerous journey to its northern district The attempt which he subsequently made to approach it from another direction, and there more accurately determine its physical constitution, proved unsuccessful. He however came within sight of the mountains, and was at least able from a distance to survey some of their chief crests. In southern Tibesti the principal mountain group is Kussi, which, according to Nachtigal, probably exceeds 8,300 feet in absolute elevation. He was informed by the natives that here the water freezes almost every year, and that the local breed of camels are covered with a thick coat, like those of the Mediterranean seaboard. The dominating summit is a cone of volcanic appearance, and, following the descriptions of his informers, Nachtigal speaks of a " natron grotto," which also contains large deposits of sulphur. Two thermal springs also flow at the foot of the mountain. The Tarso, a northern group of hills traversed by Nachtigal, certainly contains a large number of volcanoes. In this district Tibesti rises above the surrounding plains in the form of abroad tableland about 3,300 feet high, and of very ea^ access, above which are scattered numerous end, or hills, some isolated, others disposed in