i62 THE DESICCATION OF AFRICA. 



the Ennedi Hills and the fair country along the river, of which 

 a sample can still be seen in the Oases of Kufra, became 



" A region of emptiness, howling and drear, 



Which man hath abandoned, from famine and fear." 



The filching of drainage areas by the Benue is still going on 

 and is reacting on the Libyan Desert to its disadvantage by 

 lessening the flow of underground water. How recent these 

 changes are can be realised by the fact that when Rolfs in 

 1874 set out from Dakhel Oasis in Egypt to cross the desert" 

 to Kufra, by a track that had been in use from time 

 immemorial, he found that dunes had risen across the route to 

 such an extent that it was no longer a practicable course. 



THE NILE. 



Of the three great rivers which flowed north and fertilised 

 North Africa in ancient times, only one remains, the Nile. 

 Owing to recent volcanic eruptions north of Lake Kivu, the 

 drainage area of Tanganyika and Kivu has been cut off from 

 the Nile, but before this happened the northerly course of the 

 Nile was as long as that of the Proto-Congo, from the Congo- 

 Zambesi divide to the Great Syrtis Gulf. Curiously enough, 

 Livingstone, when exploring Lake Nyasa, was told by a native 

 that Tanganyika was of the same shape as that of Lake Nyasa, 

 but that the outlet was on the north of the lake, instead of, as 

 in Lake Nyasa, on the south ; as the native had not seen this 

 himself, Livingstone dismisses the statement as a piece of Arab 

 geography, but the fact remains, that the M'fumbiro volcanoes, 

 north of Lake Kivu, have only recently been thrown up; it may 

 well be that the Arab slave-hunters, not long before Living- 

 stone's time, did actually see Tanganyika discharging north- 

 wards, into the Nile. 



The Nile, however, is by no means a simple river, and 

 there is abundant evidence that important changes have taken 

 place in fairly recent times. The most striking feature is the 

 S-shaped bend in the Nubian region, stretching across the 

 southern bend from some distance above Khartoum to 

 Ambukol, where the river runs south-west, and then resumes 

 its northerly course, there is a deep channel, the Wady 

 Mokattem. It is now dry, but it once was the main stream of 

 the Nile, making a straight course for the Blue Nile, from the 

 Ethiopian uplands, in a north-westerly direction. There is no 

 question here of headstream erosion, or river capture, for the 

 volcanoes in the Bayuda bend of the Nile, Magaga, Ghilif and 

 Ghekdul, are the cause of the deflection, that is to say, the 

 accumulations of lavas and ash piled up to such an extent that 

 they turned aside the river. The Blue Nile, then, ran north- 

 west, down the Wady Mokattem to Ambukol, thence along the 



