130 E. C. ANDREWS. 



It must, however, be distinctly understood that though 

 the stream has now no opportunity (except on narrow 

 ridges) to effect much corrasion of live rock structures, 

 nevertheless, as the rocks themselves become broken up by 

 the action of the weather, so little by little the stream 

 removes the incoherent mass so produced towards the sea. 

 Thus the channel bases ever approach the main sea level. 

 Because of the relative greater relief of the interstream 

 areas, however, the latter will be more rapidly worn down 

 to the general level of reduction by erosion than the main 

 channel bases themselves. Thus the country tends ever 

 more and more to the plain stage, and the youthful topo- 

 graphic form becomes less and less possible. The convex 

 profiles which characterise the actual crests, even in the 

 youthful stage of dissection, ever grow wider and wider, 

 and become ever more and more important features of the 

 landscape, until, as in the case of the majority of the inland 

 country of New South Wales, the summits of the gentle 

 hill slopes can only be seen from points at some distance 

 from their bases owing to their convexity of slope. This 

 is the slow aggradation of the hillside, owing to the 

 supremacy of weathering agencies over those of corrasion 

 and transport. 



Davis' vivid picture of the death of the plateau shows 

 how its features diverge more and more from those of 

 youthful attack. 1 It may be noted, however, that in sub- 

 arid New South Wales, as at Oobar, numerous narrow and 

 steep ridges or peaks with steep rocky thalwegs dot the 

 great plain of denudation. These represent the action of 

 fierce thunderstorms on resistant rock ridges in an area 

 which is not much influenced by weathering. 



We have then by this slow but fairly safe route reached 

 the following important conclusion : — 



1 Journal of Geology, 1902. 



