78 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



Sutherland, '92, p. G9). In the attempt to do justice to the beauty of 

 his native province, many a Nova Scotian has kept our facet in the back- 

 ground and has laid an undue amount of stress on the hilly nature of 

 the plateau ; in certain instances he has literally made " mountains out 

 of mole-hills," apparently with the mistaken notion that the true lover 

 of nature cannot be especially interested in her land-forms when they are 

 subdued. Yet the marvel of Nova Scotian scenery lies in its flatness. 



We have, then, to explain for this area several distinct facts : (1) The 

 actual low relief everywhere contrasts with a former strong relief of 

 earlier geological time. (2) The present surface is a consequence of the 

 truncation of the outcropping edges of stratified beds of various ages and 

 structures, — destruction of such magnitude as to lay bare certain of the 

 vast igneous cores within the Devonian mountain-chain. The different 

 rock-members are not only structurally diverse and chronologically dis- 

 tinct; they vary in hardness, although they are all absolutely resistant 

 to the weather on account of their well advanced consolidation during 

 the long stretches of geological time, and because of the intense crush of 

 mountain-building. (3) Our problem is even more special than to recog- 

 nize that ten thousand feet of elevation on serrate mountain-ridges has 

 been exchanged for maximum heights of from six hundred to one thou- 

 sand feet. We must also account for a general accordance of summit- 

 levels which fall into, or nearly into, the common plane of a topographic 

 facet gently inclined towards the south ; the fact of this attitude is just 

 as clear as the low absolute range of the elevations. (4) The isolated 

 knobs, cones, and swells of bed-rock rising above the facet, and the val- 

 leys incised beneath it, must find a place in our theory of the plateau. 



Fortunately, we are not here compelled to break wholly new ground 

 in the interpretation of the Nova Scotia plateau. All will agree that it 

 is an old mountain mass worn down to far less than its original relief. 

 So limited, the problem resolves itself into the question as to how and 

 when the work of denudation and the truncation of the rock-members 

 was carried on. 



Of the manner of erosion in such a region three hypotheses have been 

 proposed; they are of unequal value, but it is advisable to note them 

 all in this connection. The oldest of all would attribute the plain of 

 denudation mainly to marine action during an extremely slow but very 

 prolonged period of subsidence beneatli the level of the sea. The second 

 would regard it as a peneplain, the final product of a completed cycle of 

 subaerial erosion, and in our case would demand a southward tilt opening 

 a new cycle as explanatory of the present position of the peneplain. 



