THE DESICCATION OF AFRICA. l6l 



by the horizontal sandstones of the Ennedi Hills. Once 

 through the gap, the course of the Proto-Congo would lie past 

 the oases of Kufra, which cover 7,000 square miles of fertile 

 ground in the centre of the Libyan Desert; thence to Augila 

 and so out to sea in the Gulf of the Great Syrtis. 



On the west of Augila, there is a valley, between the 

 Tasili and the Azdjer, on the south, and the Black Hills on the 

 north, in which lies the great oasis of the Fezzan. It is a very 

 large, fertile district, with vast, dry river courses directed 

 towards our supposed former river, as if to join it as tributaries. 

 Here, again, we have evidence of a former, much more plentiful 

 rainfall. 



At Augila, there is a great wady, the Bessame-Schecherre, 

 which is in the form of a horseshoe, with the rounded end point- 

 ing south. This rounded end would have received our sup- 

 posed Proto-Congo ; the eastern portion was connected with the 

 Nile through the Oasis of Siwa and the Bahr-bila-ma, while 

 the western branch led to the sea. At one time it was thought 

 that the Augila Oasis, together with the depressions to the east, 

 formed an arm of the Mediterranean; this theory was due to a 

 wrong estimation of the height of Augila above sea-level. 

 Rolfs first put this height as 100 feet below, but later measure- 

 ments have fixed it at 130 feet above the Mediterranean level. 

 From this supposed inland sea, the great fertility of the 

 Fezzan, in early historic times, was thought to be due ; this, 

 however, would be far more naturally explained by the fact of 

 the Congo waters flowing through the desert and fertilising 

 the neighbouring lands, as one river, the Nile, still fortunately 

 does. On the coast, north of Augila, is the Barka Plateau, 

 where about 600 B.C. flourished five cities of the most astonish- 

 ing luxuriance, Gyrene, Apollonia, Arsinoe, Berenice and 

 Barke (Ptelomais), constituting the Pentapolis of Cyrenaica. 

 One can picture the condition of things in those times. The 

 great river passing the Tibesti Highlands, which, precipitating 

 the moisture drawn from the fertile valleys at their base, sent 

 many tributaries to join it ; from there to the sea, a well-watered 

 land, with pastures stretching eastwards till they united with 

 those along the Nile and, on the west, the whole of the Fezzan 

 a continuous tract of luxuriant vegetation. All the wealth of 

 this back country reached the cities of Cyrenaica, which 

 attained an opulence quite unexplainable on other grounds. 

 Then the coastal river, far to the south, eating back through 

 the coastal rampart, tapped the headstreams and, century by 

 century, captured more waters, till the whole of the Congo 

 drainage was diverted ; the head of the river system then began 

 where the Gribingi now does. Then the Benue, eating inland, 

 captured a great part of the effective drainage area still left. 

 The river flood was no longer able to surmount the barrier of 



