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smooth and in places polish the underlying rocks. After the 

 culmination of this period of cold, wliich was probably to some 

 extent due to elevation of the continent, there succeeded an era of 

 milder climate, with partial submergence, followed again by a period of 

 ve-elevation and increased cold, with a partial recurrence of the former 

 glacial conditions, after whicli gradually the ice retreated northward 

 and the present condition of surface began to be assumed. Traces of 

 the ice age yet exist in the elevated areas of the highest mountain 

 ranees even in compai'atively low latitudes, and glaciers of considerable 

 size are found in the Rocky Mountains of British Columbia at the 

 present day. 



. The presence of the ice sheet is recognized by its mai'kings upon the 

 exposed rock surface. Instances of this are common on the ledges 

 about Ottawa and even in the heart of the city itself, the grooving and 

 striation of the surface due to the planing of the ice being well seen in 

 the quarry at the corner of Sussex and Rideau streets. In many 

 cases also the action of ice is recognized by the presence of smoothly- 

 rounded hill slopes. The direction in which the ice passed if the 

 exposed striated surfaces are well seen, can generally be told from the 

 shape or contour of the elevations. Thus the rock surfaces away from 

 the direction of ice-flow, called the " lee side," are usually rough and 

 weather-worn, while those which face the direction of the flow are all 

 ice worn ; hence the term stoss selte, or struck side, is applied to the 

 latter. 



In opposition to the theory of a great universal ice cap of immense 

 thickness just stated is the view now entertained by many that the 

 most of the glacial phenomena were caused rather by a number of small 

 or local glaciers which had their source about the summits presumably 

 of every mountain range, and in their course followed the pi'evailing 

 configuration of the surface. This view is well supported by the direc- 

 tion of the rock striations in the provinces of Quebec, New Brunswick 

 and Nova Scotia, where the evidences in favor of a great south-easterly 

 moving ice slieet are very few, and where the indications evidently 

 point in the other direction or in favor of local glaciers. 



Among the supposed indii;ations of the presence of a great ice 

 .sheet, besides the striation of the rock, is the presence of scattered 



