282 
THE BASIN OF EASTERN PERSIA AND SISTAN. 
retreat of the waters. The most important plains, however, are the deltas of the 
larger streams on the northern and eastern sides of the "haniiin." Most of these lie 
in Afghanistan and are almost unknown, but the largest, that of the Helmund, is 
partly in Persia and has been frequently described. To the eye the delta seems to be 
a flat plain, merging into the reed-beds on the one hand and ending abruptly at the 
foot of the bluffs on the other. Toward the lake the soil is clayey like the lake 
bottom, and is exceedingly slippery and stick)- in wet weather. Toward the head 
of the delta it gradually changes to very fine sand, in which there is a considerable 
proportion of clay. Everj-where the soil is fertile if properly irrigated. Where 
cultivation is carried on, the whole countr}- is often half under water. Deep and 
Fig. 167. — Canals in the Delta of the Helmund at Sistan. One canal crosses the other upon a bridge of weeds. 
rarel)- bridged canals wander here and there, and even cross one another on bridges, 
which are nothing but dried weeds packed into the water and covered with clayey 
soil (fig. 167). Grain and melons grow luxuriantly, but other crops are rare and 
fruit can not be raised because of the wind. At present large tracts are not under 
cultivation and are covered with a spiny growth of camel thorn bearing purple-pink 
flowers, or with a dense growth of tall tamarisks forming an almost impenetrable 
jungle 20 feet high, the home of innumerable wild boars and jackals. In still 
other places, as at Zahidan, the delta is being invaded and buried by sand. At first 
sight there appears to be no special reason win- certain areas should be cultivated, 
others should be left to camel thorn, still others should be covered with tamarisks, 
while the most unfortunate parts are being destroyed by sand. The explanation is 
