137 



The present geographical location of these divisions is 

 due primarily to Palaeozoic constructive and mountain- 

 making processes, as expressed in deposition, folding, 

 and faulting, and secondarily to Mesozoic, Tertiary and 

 Quaternary destructive and epeirogenetic processes, as 

 expressed in erosion and vertical warping. The deform- 

 ative processes of Palaeozoic time have determined the 

 general northeasterly-southwesterly trend of the structural 

 axes, while the differential vertical movements of post- 

 Palaeozoic time, working largely independently of structure, 

 have controlled the present surface features. 



CRETACEOUS AND TERTIARY PENEPLAINS. 



The pre-Carboniferous uplands comprise the highlands 

 of New Brunswick, the Cobequid hills, and the Southern 

 upland or plateau of Nova Scotia. Daly [lj has furnished 

 evidence to support the hypothesis that these surfaces 

 represent remnants of a once continuous and more extensive 

 Mesozoic peneplain. The age of the peneplanation was 

 assigned by him to the Cretaceous by correlation with 

 the New England and southern Appalachian land forms. 

 The basic argument for this interpretation is the remark- 

 able discordance of surface form with underlying structure. 

 Vertical uplift and warping, accompanied by southeasterly 

 tilting, in early Tertiary time exposed the old-age surface 

 to renewed differential denudation, resulting finally in the 

 sculpture of a local Tertiary base — a levelled surface on 

 the softer Carboniferous rocks. But the ancient complex 

 of more resistant rock still upholds large areas of the older 

 or Cretaceous plain and so preserves the historical record 

 of erosion. 



TRIASSIC LOWLAND. 



The history of the Triassic lowland, or Bay of Fundy 

 region, is necessarily involved in that of the Carboniferous 

 lowland, but is further complicated by the addition of 

 tidal scour to subaerial processes as an active though 

 variable denuding agent, and by the fact that the processes 

 of destruction worked on a peculiar type of constructional 

 topography, apparently the resultant forms of monoclinal 

 faulting [2j, parallel to the older land areas. The modified 

 result has its expression in such features as the trap ridge 

 of North mountain. 



