274 NORTH-EAST AFRICA. a circular enclosure. In the more remote regions of central Dar-F6r are also a few isolated uplands. The confines of "NVadai, towards the north-west angle of Dar-F6r, are indicated from afar by the Jebel-AbCl-Ahraz, or the " Mountain of the Father of the Acacias." A second height, better known, as it commands the caravan route from Kobch to Siut to the west, develops its peaks, such as the Jebel-Dor and the Jebel-Anka, in a line with the northern continuation of the main axis of the Marrah range. To the north-east of Dar-F6r, the Jebel-Medob lifts its sandstone walls and granite cupolas, here and there broken by lava streams, to a height of nearly 4,000 feet. Beyond this point extends the plateau of the Jebel-Ain, skirted by the "Wady-^Ielek. To the east the Jebel-el-Hillet, which is skirted by the route from El-Fasher to El-Obeid, and to the south, in the hydrographic basin of the Bahr-el- Arab, are still seyeral other isolated uplands, connected by no intermediate ridges with the Marrah highlands. The Jebel-IIadid, one of these groups of hills, is very rich in iron ores. Some 30 miles to the south-west of the Jebel-Dango, another mountain mass rising above a plain, are the copper-mines of Ilofrah, celebrated throughout the whole of central Africa. The mineral vein which is now being worked lies on the right bank of the Bahr-el-Fertit, an affluent of the Bahr-el-Arab. An excavation, 500 feet long by 50 feet broad, with a mean depth of 10 feet, has been dug out by the miners, and shafts, now abandoned, have been sunk in all directions within a radius of 1,660 feet from the pit. It was mainly with a view to obtain these copper-mines that the Khedive caused Dar-F6r to be occupied. Few other regions have been the cause of more wars between the African populations than these now valueless mineral beds. Hydrographic System. The rainfall and the waters of the wadies are regulated by the atmospheric currents, as in Kordofan ; however, it would appear that the higher mean elevation and the greater extent of the Dar-F6r highlands cause more of the rain-bearing winds to be arrested, thus securing a more copious rainfall for this region. Near the centre of this mountainous district, in a closed amphitheatre, lies a lake which has never yet been visited by European travellers. The rains are more abundant in the western region of Dar-F6r ; and as the concave side of the crescent-shaped Marrah range faces westwards, the water- courses of this watershed all converge on the main branch, the Wady-Azum, a relatively copious stream, although its bed is dry for a portion of the year. On the convex slope of the Marrah Mountains the running waters, diverging east and southwards, become lost in the desert, and hence are unable to unite their sandy beds in one common hydrographic system. On the southern slope alone, where the rains fall more frequently, the rivers have a longer course and" constitute veritable fluvial basins. Thus, during the rainy season, the Wady-Amor and the Wady-el-K6 combine to fill a rahad or lake of some considerable size, at which the Rizegat Bagg&ras water their cattle.
