38 MOZAMBIQUE 



is all good sugar land ; indeed the greater portion 

 of the land through which the river passes from 

 the junction of the Chire to the muddy mangrove 

 flats of the lower delta is too sandy to be classed 

 as good sugar land, but rich argillaceous deposits 

 occur, and their united areas must be considerable. 



This sandy formation, apart from its direct 

 bearing upon the fertihty of the soil, is the origin 

 of physical effects of some importance to agricul- 

 ture. The banks are continually crumbling away, 

 and the bed of the river is becoming ever wider 

 and wider. This is in contrast to the Incomati, 

 whose banks, mainly composed of alluvium and 

 organic matter, not subject to scour like sand, 

 and protected by a thick growth of reeds and 

 creeping aquatic grasses which encroach upon the 

 water, are, it would seem, contracting, and the 

 river, now confined within narrow limits, is prob- 

 ably but a shiver of what it once was. These 

 conditions are favourable for irrigation, because 

 instead of a wide shoaling stream like that of the 

 Zambezi we have a single deep channel. But, on 

 the other hand, it is obvious that a swollen stream, 

 cramped up within a narrowing bed, is much more 

 likely to overflow and seriously inundate the 

 adjacent lands than one that is always extending 

 its boundaries. 



Permanent irrigation pumps can only be estab- 



