492 J. AV. BEWS. 



during the dry season. Iron salts may also be precipitated 

 by coming into contact with other salts, but this process does 

 not seem so likely in the case of the iron-pan formation in 

 Natal. The soil becomes cemented together by the precipi- 

 tated iron oxide (limonite). The iron-pan thus formed is 

 known as " oud klip " or " on klip " in South Africa. The 

 limonite is formed below the surface, but it is frequently 

 exposed if subsequently washed bare of surface soil, and then 

 the ground is covered by masses of the ironstone gravel. 

 The soil drainage is interfered with by this hard layer of 

 limonite. Water cannot rise through it from below nor sink 

 through it from above. Sometimes, however, it is porous and 

 this result does not follow. 



The characteristic vegetation of such iron-pans may be 

 described in this place instead of later. They may be recog- 

 nised from a long distance by the white covering of Heli- 

 c h r y s u m a u r e o - n i t e n s . It is a very xerophy tic plant with 

 a white woolly covering of hairs. Lobelia decipiens is 

 another characteristic species, and Drosera burkeana is 

 often present. 



(2) Low Veld Region. 



In the main valleys of the Umgeni and Umsindusi the 

 conditions are markedly different from those of the high veld 

 region. In some places the rivers have cut down very steepl}^ 

 leaving rocky slopes, and even cliffs (see PI. XLII) ; in other 

 places broad alluvial flats are formed (see PI. XL). The 

 valleys as a whole are only a degree less rugged than the 

 higher regions. 



The alluvial soil of the river flats is a hard, dry, compact 

 clay, much richer chemically than the soil of the high veld, 

 but badly aerated. The iron it contains exists as the prot- 

 oxide (FeO). There is a certain amount of organic matter 

 mixed with the clay, and the soil is dark in colour. Nodules 

 of precipitated limonite are abundant in places. Lime is also 

 re-deposited in the same way, but in Natal (at least in the 



