THE ATLAS JNTERMONT PLATEAUS 203 



the range. In this region the rainfall is greatly reduced 

 and the climate is semi-desert, although heavy downpours 

 may occasionally cause disastrous floods. The variations 

 of heat and cold are necessarily greater than in the 

 surrounding lowlands. 



These high plains give us a foretaste of the great desert. 

 At first sight there seems to be nothing but a boundless 

 sea of scattered tufts of alfa or esparto grass over 

 stony plateaus. Soon, however, one discovers a network 

 of broad and winding, waterless river-beds converging 

 towards the shallow shotts. These are marked by other 

 steppes, covered chiefly with wormwood, in small whitish 

 bunches. The saline tracts surrounding the shotts are 

 laid out in belts of fleshy salt-bushes or succulents. 

 Small dunes may interrupt these belts. They are the 

 home of a desert-grass, the ' drinn ' (aristida pungens), 

 a favourite fodder of camels. Trees are absent, or con- 

 fined to some isolated and thin orchards in the more 

 fertile hollows with some ground moisture. They are 

 reduced to the size and shape of shrubs such as the 

 batoum pistacio and the thorny jujube-tree. 



Amid such arid tracts, fresh- water sources and oases 

 are welcome features. Large oases line the southern 

 shelf of the Saharan Atlas : the largest of them, Figuig, 

 Ain-Sefra, Laghuat, Biskra, appear like seas of waving 

 date-palms. They are the true gates of the desert, 

 the starting-points of those thin straggling lines of 

 travel which span the immensity; but there are hun- 

 dreds of other sources of water, in which man has 

 bored wells. By thus tapping and utilizing the waters, he 

 has dotted the desert with fertile orchards arid gardens 

 of fresh verdure. 



As might be expected, the Saharan Atlas is much 

 drier than the northern branch ; the slopes are now 



