The veld as an uplifted peneplain 437 



If the original low-lying peneplain were more or less uplifted by warp- 

 ing and faulting, so that a large central area might reach a considerable 

 altitude, while the marginal areas might remain either quiescent or even 

 suffer depression beneath the sea, no coastal plain of marine strata would 

 be expected around the resulting continental border. The uplifted high- 

 land area would during and after elevation suffer dissection by its revived 

 river systems, particularly in those marginal areas where the slope of the 

 river courses was increased by the warping. Over the more evenly up- 

 lifted highland there might be for some time little indication of uplift 

 in the way of stream dissection; for a number of examples of uplifted 

 peneplains may be cited where, although more or less dissection has taken 

 place along the middle and lower courses of the revived rivers, the upper 

 courses still flow essentially on the upland level as if they had not yet 

 received any intimation of revival. Nevertheless, in the case of so large 

 an area as that of the Veld, it is difficult to imagine an uplift to proceed 

 with such perfect equability as not to disturb the delicate relation that 

 must have previously existed between the well graded rivers of the pene- 

 plain and the gently sloping surface which they drained. Had there 

 been here and there ever so gentle a warping, the rivers would have had 

 to incise their channels beneath the plain where their slopes were in- 

 creased, and would have had to aggrade the plain where their slopes were 

 decreased, thus reestablishing the relation that warping had disturbed. 

 Yet no distinct examples of locally incised rivers or of broad alluvial de- 

 posits were noticed during our journey of over 2,000 miles across the 

 Veld, unless it may be that certain shallow valleys near Bulawayo are thus 

 to be interpreted, and that the heavier local sheets of waste which we saw 

 at a few places should be explained as the result of local down-warping, 

 instead of being regarded as due to long-period weather variations, as has 

 already been suggested; but these deposits are at most of small extent. 

 As a rule, the absence of incision and of deposition would seem to dis- 

 prove the occurrence of warping since peneplanation, and thus to render 

 broad elevation also rather improbable. 



It might, however, be suggested that the elevation of the region took 

 place, with more or less warping, so long ago that later erosion has again 

 smoothed it out to a new peneplain ; but in that case one might well ex- 

 pect that the dissection of the peneplain as a whole with respect to present 

 sealevel should be more advanced than it is. Indeed, it is a necessary 

 corollary of the moderate amount of dissection that the Veld as a whole 

 exhibits with respect to present baselevel than any elevation that it has 

 suffered since peneplanation can not have taken place at a very remote 

 date. 



