82 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



appealed to for explanation of the upland facet of the Southern Plateau, 

 cannot as yet be asserted with the confidence of full proof; to attain it, 

 much additional field-work would be necessary. What is needed is 

 some such evidence as that of the subaerial origin of the inlaud lowlands 

 of Pennsylvania, which, on account of their enclosed nature, cannot 

 have been effectively reached by the sea. The apparently complete 

 lack of coastal sediments on the facet is suggestive of the subaerial ex- 

 planation, but it is open to question whether such an overlap of neces- 

 sarily weak rocks would not have been quite removed by general land- 

 erosion, during the long time required to excavate the Fundy lowlands 

 beneath the upland facet. The known inferiority of shore forces to 

 erode as compared with atmospheric agencies of wear is not, if time 

 enough and appropriate crustal conditions be granted, an antecedent 

 objection to the marine hypothesis. 



Yet there are certain reasons why greater satisfaction may be felt 

 with the peneplain hypothesis. The occurrence of residuals just where 

 the waves would have especially great destructive power can hardly be 

 accounted for as a result of differential hardness. The very perfect 

 adjustment of drainage-courses to soft rock-belts in the Triassic area 

 hereafter described will be found to bear striking resemblance to similar 

 adjustment among the trap ridges of New Jersey, and to afford grounds 

 for a similar explanation of the phenomenon as the product of two 

 cycles of land wasting. So close are the similarities existing between 

 the Nova Scotian plateau, on the one hand, and the New England, 

 New Jersey, and Southern Appalachian plateaus, on the other, that one 

 cannot resist the conclusion that it is simplest to find a common expla- 

 nation for the greater denudation in the whole belt. One of the chief 

 recommendations for the peneplain theory as applied to the southern 

 province is the fact that, if we grant the truth of the theory, a more 

 complete and consistent account can be given of the multitude of land- 

 forms associated with the larger facets. The same is believed to be 

 true here. Bearing in mind the lack of complete demonstration for the 

 peneplain character of the Southern Plateau, we shall yet posit such a 

 character and proceed to inquire whether or not the topographic divi- 

 sions of Acadia are in accordant, organic relationship with that facet. 



Extension of the Southern Plateau Facet. — In his definition 

 of the term " peneplain " Professor Davis noted a considerable area as 

 one of its necessary characteristics ; this for the reason that, during the 

 long lifetime of the cycle in which planation is established, denudation 

 will hold extensive sway even over harder rocks, and they will be re- 



