78 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 
Sutherland, ’92, p. 69). 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 beneath 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. 
