64 THE ICE AGE IN CANADA. 



these are masses of the hard sandstones of the lower 

 Silurian rock of the south coast, and occasionally, though 

 rarely, blocks of the upper Silurian limestone of the 

 inland hills to the south. 



The boulders of this belt, though stationary in summer, 

 are often moved by the coast-ice in winter. This is well 

 seen where they have been removed to form tracks 

 for launching boats. In this case it is not unusual 

 to find in the spring that such tracks have been partially 

 refilled with boulders. On my own property, a track of 

 this kind was completely blocked a few years ago by an 

 angular boulder of sandstone nine feet in length, which 

 had been lifted from a spot a few feet distant ; and it is 

 quite usual to find in a boat-track, cleared in the previous 

 svimmer, a dozen boulders of two feet or more in diameter 

 that have been dropped in it by the winter ice. Whether 

 any of these blocks are being drifted at the present time 

 from the north shore is not known ; but they are moved 

 freely up and down the coast, and in dredging in depths 

 of eight to fifteen fathoms, I have found evidence that 

 large boulders are not uncommon on the bottom ; and 

 judging from the small specimens taken up by the dredge» 

 they are similar to those on the shore, though apparently 

 with a larger proportion of flat, slaty fragments. 



If the coast were now in process of subsidence, there 

 can be no question that the boulders would be pushed 

 upward, and would eventually form sheets and ridges of 

 boulders embedded in mud, much in the manner of the 

 marine boulder-clays now found inland. 



Above high water, on certain portions of the coast, 

 there is a low terrace, only a few feet above the sea, and 

 consisting of sand, shingle, and gravel, often with frag- 

 ments of marine shells. Boulders are not numerous on 



