74 TlIK iC'K A(iK IX CANADA. 



Huvatilc (U'liuiliitioii in I'lioceiie nnd pro-PliDceno tiiiios 

 lias cul a trench to a dt'itih u|' SOO fccL lu'l^w llic jn't'st'iit 

 water le\-el ot' the St. Lawrence, and that the glacial 

 action of the IMeistoceni! has |)oHshe(l and ^rooveil its sides 

 and prohaldy its hoUoni,and piled up dihris at its nuaith.* 

 1 need hardly say, after the discussions on the suhj'ect, 

 that the reference of the cuttint^' of lake hasins and tiords 

 to glacit'rs in the ice au'e, aiiidnst which I have argued 

 ever since 1<S()(], has hecii altogether exploded. 



(1) This heing admitted, and also the fact e.stahlishe(h 

 by the most comincing evidence, of the great depression 

 of our continents in the glacial or I'leistocene age, it 

 follows that the first or oldest of the Pleistocene de])osits, 

 the till or houlder-clav, ^vas laid down durinu; a time of 

 subsidence, in which tlu! northern land was slowly sinking 

 under the sea. AVe leave untouched at present the mode 

 of deposition of houlder-cday and of polishing and stria- 

 tioii of rock-surfaces under it, merely nesting that the 

 boulder-clay proper is confined to the plains and valleys, 

 where it often contains marine remains. The hills show- 

 evidence of glacier-movement down their valleys, and 

 of the formation of moraines, and sometimes of patches 

 of an indurated ground moraine or hard till, dill'erent 

 from ordinary boulder-clay. 



(2) The formation of the Leda clay and interglacial 

 deposits, and of the similar deposits on the western 

 plains, belongs to the time when this region had subsided 

 beneath the waters, with tracts and islands of higher 

 lands projecting. The dillerential character of this eleva- 

 tion, whereby certain parts of the then submerged areas 

 stood higher than others, will be mentioned later. 



* Notes on Pleistocene of Canada, 1872. 



