376 Geographical Notices. 
a plateau of 2000 feet in altitude which stretched away in an 
unbroken surface of from 1860 to 1590 feet, as far as Mursuk, 
and hence it appeared probable that the Mursuk plateau at its 
eastern extremity merges into the Hamadah. From Aschenum- 
ma, in the neighborhood of Bilma, Vogel writes: “I have as- 
certained that the Great Desert is one vast plateau formation, of 
the general height of from 1200 to 1500 feet.” 
ith these data before us, based as they are upon scientific 
research, we are prepared to give credence to the reports of the 
natives respecting the mountainous character of many portions 
of the Sahara. The whole southern region of the Tibbus Desert 
(Lybian) appears from such reports to be covered with high 
mountains and mountain ranges; in fact, near its southern bor- 
der two remarkable mountain clusters have been discovered, the 
+ 
Borghu and the Uadschunga, which are so elevated that the na- 
as, for instance, of the Black Mountains, which extend from t 
coast far to the inland, and of a mountain chain fringed on its east- 
ern border by several oases, that of Tuat, among the rest: but 
especially renowned is the frowning Haghar group, with its three 
or four sheer, steep and dizzy walls of rock, each wall 125 miles 
in length; this is said to be surrounded by an immeasurable - 
of sand, and to form the stronghold of the most powerful an 
the most predatory of all the Tuareg tribes, that of the <— 
and Timbuctoo, is the most remarkable in extent ; and it 
be a question whether a scientific exploration will not re 
2 existence of the plateau formation at least in some POT 
