46 AN OUTLINE OF THE 



the facts by which the geological history of Mount Desert 

 may be interpreted. 



Seldom are geological facts more plainly presented. 

 Seldom have pleasanter days been spent than those 

 recalled while writing out this sketch. We have coasted 

 in good company and under good pilotage along the rocky 

 shore, landing for our geological discoveries even as old 

 Champlain may have landed for his geography, and return- 

 ing to our vessel at night. We have clambered up pathless 

 glens to rugged summits ; and if we carried rations for 

 only half a day, we felt nevertheless the spirit of explorers 

 in unknown lands, and our adventures were recounted 

 around camp-fires in the evening. Our vacations are 

 shorter now than then, and while recalling them in this 

 writing we must leave to others the pleasures on sea and 

 shore once our own. 



THE GRANITE BELT. 



The granitic mass of Green Mountain, and of its domi- 

 nant fellows east and west, and of a belt of adjacent 

 lowland across the Island about parallel to the range, 

 serves as a natural beginning in our study, and from the 

 date of the origin of the granite we may go backwards 

 and forwards in time until the whole sequence of events 

 discoverable within our borders is determined. The rocks 

 of the mountain belt, wherever examined on summits or 

 flanks, have a remarkably uniform crystalline texture, 

 consisting of an intimate mixture of quartz, feldspar, and 

 hornblende, to which the name of hornblendic granite is 

 given. The constituent minerals may be easily recognized 

 by the unaided eye : the quartz being translucent and 

 glassy, with uneven surface ; the feldspar, gray or pink, 

 with even cleavage surfaces ; the hornblende, black, and 

 in smaller particles than the other minerals. The massive 

 structure of this rock, in so strong a contrast to the bedded 



