Igharghar. Its central division is occupied by the so-called gada, large stono tables with steep vertical cliffs flanked by long taluses. Round these great chalk masses wind deep gorges communicating with each other by fissures in the plateau. The Tuila Makna, their culminating point, connecting the Amur with the Geryville highlands, has an elevation of 6,330 feet. But, if not the highest, the most imposing crests are those rising in the south above the terminal spur known as the Kef-Guebli.
East of the Amur system the highlands fall gradually in elevation and contract in width, being reduced north-west of Biskra to a narrow ridge, which scarcely separates the Hodna depression on the north from that of Ziban on the south. Here
the railway from Batna to Biskra is uble to cross the hills without tunnelling, by following the gorge of the Wed-el-Kantara down to the southern plains. But this line has to describe a great bend round the western extremity of the Jebel Aures, the loftiest range in Algeria. This system, however, lacks the symmetry of outline characteristic of most other Algerian uplands. The highest northern crests deviate somewhat from the normal direction, being gradually inclined from west to east, and on the whole presenting the form of a slightly opened fan. In the northern range towers Mount Sheliya, the giant of the Algerian highlands, whose supreme peak, the Kelthum (7,760 feet) exceeds by some yards the Lalla-Khedija, in the
