34^ THE GREAT ICE AGE 



a lower barrier of earth waves composed of sedimentary rocks 

 somewhat later in date, but still geologically very ancient. We 

 are thus introduced to a remarkable feature of the west side 

 of the North Atlantic, namely, that its border is made up of 

 very old rocks folded into mountain ridges thrown up at an 

 ancient period, and approximately parallel to the coast. The 

 Lower St. Lawrence occupies a furrow between two of these 

 ridges. 



Here, however, a more modern feature attracts our attention. 

 The sides of the bounding hills are cut in a succession of 

 terraces, rising one above another from the level of the sea 

 to a height of 500 feet or more, capped with long ranges of 

 the white houses and barns of the Canadian habitants, and 

 furnishing level lines for the " concession roads " which run 

 along the coast. These terraces are really old sea margins 

 indicating the stages of the elevation of the land out of the 

 sea immediately before the modern period. On these terraces, 

 and in the clays and sands which form the plateaus extend- 

 ing in some places in front of them, are sea shells of the 

 same kinds with those now living in the Gulf of St. Lawrence, 

 and occasionally we find bones of whales which have been 

 stranded on the old beaches. 



These terraces are, of course, indications of change of level 

 in very modern times. They show that in what we call the 

 Pleistocene age the land was lower than at present, and we 

 shall find that in the Lower St. Lawrence there is evidence 

 of a depression extending to over 1,000 feet, carrying the 

 sea far up the valley, so that sea shells are found in the clays 

 as far up as Kingston and Ottawa, and stranded skeletons 

 of whales as far west as Smith's Falls, in Ontario. 



If we examine the shores more minutely, we shall find all 

 along the south coast a belt of boulders which are often as 

 much as eight to ten feet in diameter, and consist largely 

 of rocks found only in the hills of the northern coast, more 



