AX (ECOLOGICAL SUKVKY OF THE MIDLANDS OF NATAL. 493 



area being considered) we do not get lime-pans such as occur 

 in other parts of South Africa. The lime forms nodules of 

 impure limestone. Sometimes, as was shown by a few rough 

 analyses, magnesium is mixed with it, and the nodules are 

 impure magnesian-limestone. 



Above the river flats the sloping ground is covered by a 

 shalloAv layer of soil, hard, dry and baked, yet at the same 

 time chemically rich owing to the constituents derived from 

 the dolerite rocks above it. This type extends up to the belt 

 which is transitional to the high veld — the higher slopes 

 where soil transportation is most rapid. 



Over the whole of this low veld, Anthistiria imberbis is 

 again the dominant grass, though its form differs from the 

 high veld variety. 



In the parts of the low veld region where the rivers or their 

 tributaries have cut through steeply, the broken character of 

 the ground produces again much greater variation and 

 unstable types. On the steepest slopes the grasses cease to 

 be dominant, and we get the most xerophytic of all the plant 

 formations in this area, or, indeed, in the whole of Natal — 

 Euphorbias, aloes and succulent plants — the rocky hillside 

 formations of the low veld region. There are gradations 

 between this and the grassland areas. Andropogon species 

 again form the grassland associations on the stony slopes. 



The most striking character of the low veld region is the 

 entire absence of the close type of bush found higher up. It 

 is replaced by thorn trees. These grow isolated or in small 

 clumps dotted over the veld, giving a characteristic park-like 

 appearance, especially on the alluvial flats. Their growth 

 forms are, as we shall see, well adapted to the conditions 

 under which they grow. 



So far prominence has been given to the influence of topo- 

 graphy on the vegetation. The soil is being washed and 

 blown down from the higher to the lower levels, and 

 this process is taking place faster on the slopes, the rate 

 depending on the steepness of the slopes. On the more level 

 ground, both in the high veld and in the loAv veld region, the 



VOL. 2, PART 4. 33 



