THE SUCCESSION OF DEPOSITS. 67 



With reference to the differences in the above heights, 

 it is to be observed that the terraces themselves slope 

 somewhat, and are uneven, and that the principal terraces 

 are sometimes complicated by minor ones dividing them 

 into little steps. It is thus somewhat difficult to obtain 

 accurate measurements. There seems, however, to be a 

 general agreement of these terraces, and this I have no 

 doubt will be found to prevail very extensively through- 

 out the lower St. Lawrence. It will be seen that three of 

 the principal terraces at Montreal correspond with three 

 of those at Murray bay; and the following facts as to 

 other parts of Canada, gleaned from the Eeports of the 

 Survey and from my own observations, will serve farther 

 to illustrate this : 



Feet. 



Kemptville, sand and littoral shells 250 



Winchester, " " " 300 



Kenyon, " " " 270 



Lockiel, " " " 264 & 290 



Hobbes' Falls, Fitzroy, sand and littoral shells 35fr 



Durham Mills, De L'Isle, " " " 289 



Upton 257 



The evidence of sea action on many of these beaches, 

 and the accumulation of shells on others, point to a some- 

 what long residence of the sea at several of the levels, 

 and to the intermittent elevation of the land. On the 

 wider terraces, at several levels it is usual to see a deposit 

 of sand and gravel corresponding to the Saxicava sand. 

 One of the most important terraces throughout the lower 

 St. Lawrence is that between 500 and 600 feet, which 

 seems to correspond with the time of deposition of the 

 principal bed of fossiliferous Leda clay. Corresponding 

 to the terraces on rising grounds are the " boars' backs," 

 kaims or eskers stretching along flat lands between pro- 



