42 



NORTH-EAST A.FEICA. 



Fig. 11. — Fkom Dufilé to Lado. 

 Scale 1 : 1,500,000. 



river in the proper sense, but merely a khor or watercourse, wliicli is becoming 

 yearly less navigable, and already inaccessible to boats except for a sbort time 

 during the floods. The whole low-lying region at present intersected by the 

 Bahr-el-Jebel, the Zaraf and all their countless affluents, channels, and branches 

 was evidently at one time a vast lake, that has been gradually filled up by the 



alluvia of these rivers. Its northern 

 margin is indicated by the abrupt 

 change in the course of the Nile at the 

 confluence of the Bahr-el-Ghazal, or 

 "Gazelle River." At this point the 

 whole system of waters is collected in 

 a single channel, which is deflected 

 eastwards along the escarpment of the 

 upland Kordofan plains. A cavity of 

 the old depression is still flooded by a 

 remnant of the lake called the No, Nu, 

 or Birket-el-Ghazal, which, however, 

 under the action of the currents and 

 periodical floods, is continually over- 

 flowing its marshy banks, shifting its 

 place and modifying its outlines. 



Nowhere else is the Nile more 

 obstructed by vegetable refuse as along 

 this section of its course. The floating 

 islands drifting with the current being 

 arrested by the abrupt winding of the 

 stream are collected together, and 

 stretch at some points right across the 

 channel, which thus becomes displaced. 

 But the new channel is soon blocked 

 by fresh masses of sedd, as it is called, 

 which in many places covers a space 

 of twelve miles. This sedd often 

 acquires great consistency, supporting 

 a dense growth of papyrus, and even 

 of arborescent vegetation, beneath 

 which the main stream continues its 

 sluggish course. Numerous families 

 of the Nuer tribe pitch their tents on the verdant surface, living exclusively on 

 fish caught by piercing the foundations of their dwellings, and on the grain of 

 various species of nymphaeaceae. In certain places along the banks of the river 

 and surrounding swamps are seen myriads of earth-mounds, all raised above the 

 highest level of the inundations by their architects, the termites, who ascend and 

 descend from story to story with the flowing and ebbing stream. One of the most 



5r50' E -of Greenwich "SS'lS 



. 30 Miles. 



