SIEUR DE MONTS NATIONAL MONUMENT. 



9 



The boldly uplifted range of Mount Desert is one of the most stubborn 

 survivors of that ancient highland, and the beauty of the island as seen 

 from the sea, unparalleled along our whole Atlantic coast, is due to its 

 persistent retention of some portion of the height which the whole region 

 once had but which nearly every other part of it has lost. 



Although the noble granitic rocks that form this range rest quiet and 

 cold in their age to-day, they were once hot and energetic, pressing 

 their way upward, as a vast molten mass, toward — and overflowing 

 possibly — the ancient surface of the land. The massive granite stretches 

 east and west across the island, inclosed wherever the attack of ice or 

 sea has failed to lay it bare by rocks of a wholly different origin and 

 character. At first these other rocks are seen as isolated fragments in- 

 cluded in the granite; the fragments then become more frequent until 



Pegmatite dike filling a rift in the granite of Pemetic Mountain. 



solid rock of their own type, strangely twisted and contorted, begins to 

 take the granite's place, as in the wonderful displays at Great Head and 

 Hunter's Beach Head; further on, the granite is only seen penetrating 

 these other rocks in long, narrow crevices, as on Sutton Island; at last 

 it ceases entirely, and the rocky floor, wherever it can be observed, is 

 wholly formed by rocks like those first seen as fragments caught and 

 frozen in the cooling granite. Near the margin of its area, again, the 

 granite is finer textured than where erosion has laid bare its ancient 

 depths, as in the mountain gorges; for it is the way of igneous, or fire- 

 formed, rocks when crystallizing from a molten state to develop smaller 

 crystals and finer texture near their boundaries, where the cooling is 

 more rapid. 



This fine texture of the margin of the granite, the inclusion of angular 

 and freshly broken fragments of the regional rocks within its borders, 



