THE DESICCATION OF AFRICA. 1 63 



bed of the Nile to Amara and then out into the desert, past the 

 oases of Charga, Dakhel and Farafra. 



The Atbara, also, flows north-west from the same high- 

 lands as the Blue Nile ; it joins the Nile above Berber and 

 flows m a straight course to Abu Hamed and then turns south- 

 west. Again, a deep wady continues the straight course of the 

 original Atbara, cutting across the bend and joining the present 

 Nile at Asaki, above Assuan ; this is the Wady Galgabba, 

 with its northern continuation, the Bahr-bila-ma, " the river 

 without water " (not the river of the same name we mentioned 

 in connection with the Siwa Oasis). The Nile, then, originally 

 w'as two rivers running parallel. Owing to the failing of the 

 Proto-Congo and the conversion of the open country into a 

 desert and consequent filling of the river-bed with sand and, 

 also, probably, owing to the lowering of the bar of syenite at 

 Assuan by the erosion of the river, giving the more easterly 

 stream a more drawing power than its western neighbour; the 

 former worked back by a side-stream across the divide and 

 tapped the western stream. The lakes of Charga then dried 

 up. 



In Upper Egypt, the Libyan Desert commences at the foot 

 of the escarpment of Lower Eocene rocks, that form a plateau 

 between it and ttie Nile. Underground water is plentiful, as 

 the oases indicate, and underground water is everywhere asso- 

 ciated with former streams above ground. We have reason, 

 therefore, to continue the western Nile on the desert side of the 

 escarpment, to Siwa, where there is the Temple of Jupiter 

 Ammon. Here was once a populous Roman city with every 

 evidence of abounding fertility in the country around it. There 

 is the other " river without water," the Bahr-bila-ma, here, 

 which is connected with the present Nile through the Fayum. 

 The Fayum is a depression into which a western branch of the 

 Nile, the Bahr-el-Yussuf, discharges, and there is still a lake, 

 the Birket-el-Qurun, in the depression, that serves as an illus- 

 tration of what existed in most of the oases in bye-gone times. 



The Bahr-el-Yussuf leaves the Nile a little below Assuan 

 and flows parallel to it for 120 miles; in the same way the 

 original western Nile, leaving its present course at Amara, 

 flowed on the western side of the Libyan Desert escarpment 

 and discharged into the Charga Oasis. There are two areas 

 of lake-deposits here, with salt-pans, indicating the connec- 

 tion of the oasis with running water m former times. From 

 Charga the escarpment runs westwards; following the foot 

 of the hills, one comes to the oasis of Dakhel (Dakla), which is 

 of a similar nature. Thence the plateau trends north-west to 

 Farafra. Siwa and Jarabub Oases lie at the foot of a table- 

 land composed of sandy Mid-Tertiary deposits, that separates 

 the Lib}'an Desert from the sea and the escarpment runs, 



