MODEL OF NEW ENGLAND. 151 



developed by erosive activities near sea-level, and that it 

 lias since been raised unevenly, so as to form a warped and 

 faulted surface. The great Ben Lomond-Guyra-Guy Fawkes- 

 Plateau is best explained as a faulted or warped portion 

 of the Sandon Level. It cannot be explained satisfactorily 

 as a residual of erosion, because the general rock types 

 composing its mass are not harder than those of the 

 associated lower areas, and, moreover, the main streams 

 head in the higher block and yet flow in relatively narrow 

 valleys, although the smaller tributaries in similar struc- 

 tures lie in relatively broad valleys. The great Dundahra 

 and allied scarps may be due either to faulting or to 

 differential erosion. 



(b) The Coast. — The plateau is connected to the coastal 

 region by rugged and youthful topography. This feature 

 is well illustrated by the model. The coastal region con- 

 sists, in the main, of structures weaker than the acid 

 granites, porphyries and rhyolites. Along the Namoi, Peel 

 and Hunter Rivers, this relative structural weakness is 

 particularly emphasised. The model indicates the geo- 

 graphic youth of the eastern edge of the plateau. Never- 

 theless, the age of the wild topography is doubtless to be 

 measured by millions of years, for all the ravines in the 

 granites have been formed by headward recession of the 

 streams, yet not one waterfall lip in the granite country 

 has receded to the extent of an inch during the last twelve 

 years according to the writer's observations, although 

 heavy floods have occurred along these watercourses during 

 such period. On the other hand, the gorges have receded 

 for many miles through granites, and this also after the 

 close of the first division of the Canon Cycle. The Hunter 

 Valley, long and wide as it is, is only as old as the Macleay 

 gulches, and these in turn are as old as the canons of the 

 Clarence and the Bellinger. The explanation appears to 



