THE EOZOIO AGES. 19 



under the waters, or have lost by denudation the 

 sediments once resting on them ; and being of a 

 hard and resisting nature, still remain, and often 

 rise into hills of considerable elevation, showing 

 as it were portions of the skeleton of the earth 

 protruding through its superficial covering. Such 

 rocks stretch along the north side of the St. Lawrence 

 river from Labrador to Lake Superior, and thence 

 northwardly to an unknown distance, constituting 

 a wild and rugged district often rising into hills 

 4000 feet high, and in the deep gorge of the 

 Saguenay forming cliffs 1,500 feet in sheer height 

 from the water's edge. South of this great ridge, 

 the isolated mass of the Adirondack Mountains 

 rises to the height of 6,000 feet, rivalling the newer, 

 though still very ancient, chain of the White Moun- 

 tains. Along the eastern coast of North America, 

 a lower ridge of Laurentian rock, only appearing 

 here and there from under the overlying sediments, 

 is seen in Newfoundland, in New Brunswick, pos- 

 sibly in Nova Scotia, and perhaps farther south in 

 Massachusetts, and as far as Maryland. In the old 

 world, rocks of this age do not, so far as known, 

 appear so extensively. They have been recognised 

 in Norway and Sweden, in the Hebrides, and in 

 Bavaria, and may, no doubt, be yet discerned in 

 other localities. Still, the grandest and most 

 instructive development of these rocks is in North 

 America; and it is there that we may best investi- 

 gate their nature, and endeavour to restore the 



