GEOLOGY OF MOUNT DESERT. 61 



nocks. The range of Mount Desert is a series of 

 Monadnocks, close to the line where the sea now lies 

 on the land. 



It is only in a later cycle of denudation, since the low- 

 land peneplain was uplifted into a rolling plateau inclining 

 towards the sea, that the valleys of New England were 

 carved out. Where the plateau rose high, the valleys 

 have been cut deep ; where it rose but little, there are only 

 shallow trenches in the upland. Where the rocks of the 

 uplifted peneplain are relatively hard, the valleys are as 

 yet, in the present cycle of denudation, opened only to a 

 moderate width ; where the rocks are weak, the valleys 

 are opened so wide that new local lowlands, local pene- 

 plains of the second order, or of a second generation, have 

 been developed. Thus the rocky floor of New England 

 is diversified, and of this rocky floor Mount Desert is a 

 little part. 



Just as we must avoid too artificial a conception of the 

 plain to which New England was reduced by the great 

 denudation, so we must guard against too rigid an assump- 

 tion of a perfect standstill of the land during either the 

 greater or the lesser cycle of its degradation, and too 

 violent an assumption of its immediate ascent from a 

 lower to a higher altitude. It is most probable that many 

 minor oscillations of level occurred during the cycle while 

 the peneplain was in development, and that the elevation 

 and tilting of the peneplain into the inclined upland was so 

 gently accomplished, that, had we then been here to watch 

 its rise, we might have watched in vain during our too brief 

 centuries. It is also probable that, since the uplift and 

 the beginning of the new cycle in which the valleys have 

 been etched out, minor oscillations have again upheaved 

 and depressed the land. It is only the greater changes 

 of level that can be detected in the more remote history 

 of the sculpture of the land ; it is only as we come close to 



