CHAPTER XXI 



LANDSCAPE, POPULATION, AND OCCUPATION 



IN the foregoing chapters particular attention has been 

 devoted to the reaction of rock structure upon drainage, and 

 the development of valley and hill systems. It remains to make 

 a few general remarks upon other landscape features. 



Plains may result from deposition of strata in a horizontal 

 position and elevation of the area above the sea level, without 

 disturbance in horizontality or sensible denudation. Of this 

 character is the eastern plain of England, the fen country, and, 

 with slight modification, the Basins of London and Hampshire. 

 Other plains result from denudation of strata, however they 

 may be situated, sufficient time not having elapsed for differential 

 effects, or else the denudation has been carried so far that a 

 base-level resulted. The first is generally the effect of marine 

 denudation. The second is the result of the river systems 

 reaching base-level, and an approach to this condition may be 

 seen in the surface of the Weald Clay, and in the plains of 

 Cheshire, York, and the Midlands which are situated on Triassic 

 rocks. 



Plateaux are little more than plains which have reached a 

 greater elevation, and they may have been plains of deposition 

 or of denudation. The great plateau traversed by the Colorado 

 River belongs to the first group. And to the second, the traces 

 of several British plateaux, like those of the Longmynd in 

 Shropshire (Fig. 47), and areas recognised by Ramsey and 

 Fearnsides, in South and North Wales. 



In both cases the plateaux are now being cut into by rivers. 

 In the earlier stages the plateau form is still easily recognisable 

 by the flat, elevated, areas between the river valleys ; but later, 

 the valleys eat their way backward and outward, consuming 

 the intervening flats, and gradually converting them into ridges 



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