192 THE ICE AGE IN CANADA. 



the ridges, along with boulders dropped from the ice 

 which drifted from the Laurentian shore to the nortli. 

 The process was slow and quiet ; so much so, that in its 

 later stages many of the boulders became encrusted with 

 the calcareous cells of marine animals before they became 

 buried in the clay. No other explanation can, I believe, 

 be given of this deposit ; and it presents a clear and 

 convincing illustration, applicable to wide areas in Eastern 

 America, of the mode of deposit of the boulder-clay. 



A similar process, though, probably, on a much smaller 

 scale, is now going on in the Gulf. Admiral Bayfield has 

 well illustrated the fact that the ice now raises, and 

 drops in new places, multitudes of boulders, and I have 

 noticed the frequent occurrence of this at present on the 

 coast of Nova Scotia. At Cacouna itself, there is, on 

 some parts of the shore, a band of large Laurentian 

 boulders between half tide and low-water mark, which 

 are moved more or less by the ice every winter, so that 

 the tracks cleared by the people for launching their boats 

 and building their fishing-wears, are in a few years filled 

 up. Wherever such boulders are dropped on banks of 

 clay in process of accumulation, a species of boulder-clay, 

 similar to that now seen on the land, must result. At 

 present sucli materials are deposited under the influence 

 of tidal currents, running alternately in opposite 

 directions ; but in the older boulder-clay period, the 

 current was probably a steady one from the north-east, 

 and comparatively little affected by the tides. 



The boulder-clay of Cacouna and Riviere-du-Loup,, 

 being at a lower level and nearer the coast than that 

 found higher up the St. Lawrence valley, is probably newer. 

 It may have been deposited after the beds of boulder-clay 

 at Montreal had emerged. That it is thus more recent,. 



