14 BIOLOGICAL SURVEY OF 



THE ISLAND OF MOUNT DESERT 



"An island full of hills and dells, 



All rumpled and uneven 

 With green recesses, sudden swells, 



And odorous valleys driven 

 So deep and straight, that always there 

 The wind is cradled to soft air." 



Elizabeth Barret Broavnixg 



Situated on the southern edge of the Boreal region, and 

 the northern line of what is known as the Transitional Zone 

 of the Austral, where the species of the so-called Canadian 

 Ufe-zone meet those from the South, the Island of Mt. Desert 

 furnishes a most fascinating place for the naturalist to study 

 the insect life. A central range of mountains rising from 

 1000 to 1500 feet forms the backbone of the Island from east 

 to west, with steep cliffs toward the east, more moderate 

 ones toward the west, and to the north and south, gentle 

 slopes which leave a section of a third of the island with an 

 altitude of about 200 feet above sea level in each direction. 



This mountain range was cut by the rivers and the ice of 

 the glacial period, which gouged out the great U-shaped valleys 

 of today, and also formed the basins which are now the lakes 

 and the fjord called Somes Sound. The mountains toward 

 the east are polished off and have a vegetation of scrub on the 

 bare granite, while the western mountains are heavily wooded. 



In a few words, by studying the geology we find that the 

 lowlands are developed on the rocks of the early Paleozoic and 

 the mountains are the hard Devonian granites, while the 

 great valleys and the lakes result from the glacial action. 

 The other features are due to the earth movement, wind, 

 frost, and the ever erroding action of the beating waves. 



Now all of this has no direct bearing upon the insects of 

 today, for the altitude of the mountains is practically elimi- 

 nated as a factor by the sea, winds, and fogs, but it has a 

 direct bearing upon the flora, and the flora and insect life are 

 merged and interdependent. 



I can best give an idea of the flora of the Island by re- 

 quoting from Part I of the Survey. 



