6o8 



ZONES AND REGIONS [Pt. Ill, Sect. II 



MULTAN IN THE PUNJAB. 



122 meters above sea-level. 



(From Zeitschr. d. osterr. Gesellsch. f. Meteorol., 1875, P- 3 2 9-) 



Rocky plateaux, built up of terrace upon terrace, and furrowed by valleys 

 with the frequently sandy wadis ; stony, sometimes hilly, sometimes flat, 

 lowland ; sandy plains usually undulating with parallel dunes ; extensive 

 loamy depressions ; all these form the immense desert district of the Sahara, 

 and sometimes alternate in rapid succession, while at other times one type 

 alone prevails over wide tracts. Notwithstanding the extreme dryness 

 of the climate, the occasional abundance of common salt, and the fact 

 that the soil except in loamy localities permits the rapid percolation 

 of the scanty rain-water, there are nevertheless few places where a glance 

 around fails to reveal a single plant. The vegetation, however, in certain 

 parts is very thinly distributed, and the individual plants, although usually 

 shrubby, are of small size. 



The least vegetation is displayed by the stony plateaux (Hamada, 

 Fig. 338) ; here, only at considerable distances apart, there rise above the 

 ground hemispherical shrubs with densely crowded thorny branches, 

 mostly belonging to the Zygophyllaceae or the Papilionaceae. Much more 



