1864.] NATURAL HISTORY SOCIETY. 225 



shown that the chansje of climate involved is not greater than that 

 which may have been due to the subsidence of land, and to the 

 change of course of the Arctic current, actually proved by the 

 deposits themselves. 



These objections miiiht be pursued to much greater length; 

 but enou2:h has been said to show that there are in the case 

 of northeastern America, strong reasons against the existence 

 of any such period of extreme glaciation as supposed by many 

 geologists; and that if we can otherwise explain the rock striation 

 and polishing, and the formation of fiords and lake-basins, the 

 strong points with these theorists, we can dispense altogether 

 with the portentous changes in physical geography involved in 

 their views, and which are not necessary to explain any of the other 

 phenomena. 



It is on these points more especially, that the Report of the 

 Geological Survey throws new light; though Sir William, with his 

 usual caution, has not committed himself to theoretical con- 

 clusions ; and in one or two local cases he seems to favor the 

 glacier theory. It has long been known to geologists, that in. 

 northeastern America, two main directions of striation of rock-sur- 

 faces occur, from northeast to southwest, and from northwest tO' 

 southeast ; and that locally the directions vary from these to north 

 and south and east and west. Various attempts have been made, but 

 without much success, to account for these directions of striation 

 by the motion of glaciers ; and while it is quite easy for any one pre- 

 possessed with this view to account in this way for the striatioa 

 in a particular valley or part of a valley, yet so may exceptional facts 

 occur as to throw doubt on the explanation, except in the case 

 of a few of the smaller and steeper mountain-gorges. 



In the Report of the Survey of Canada a valuable table of these 

 striations is given, from which it appears that they are locally 

 distributed in such a way as to throw a decided gleam of light on 

 their origin. 



It would seem that the dominant direction in the valley of the 

 St. Lawrence, along the high lands to the north of it, and across 

 western New York, is northeast and southwest ; and that there is 

 another series of scratches running nearly at right angles to the 

 former, across the neck of land between Georgian Bay and Lake 

 Ontario, down the valley of the Ottawa, and across parts of the 

 Eastern Townships, connecting with the prevalent southeast 



Vol. L p No. 3. 



