166 THE CANADIAN NATURALIST. [Vol. vi. 



THE POST PLIOCENE GEOLOGY OF CANADA, 



By J. W. DAWSON, LL.D., F.R.S., F.G.S. 



PART II. — LOCAL DETAILS. 



Before entering into the special consideration of this Second 

 Part of the subject, I desire to call attention to some additional 

 facts bearing on two of the most remarkable properties of the 

 Post-pliocene deposits of the Northern Hemisphere, namely their 

 general similarity of arrangement, and their local diversities. 



In the first part of this memoir, taking the Post-pliocene of 

 the Lower St. Lawrence as a type, I showed that it has its paral- 

 lel, with but slight general diiFerence, in the wide-spread superficial 

 deposits of the interior of North America surrounding the great 

 lakes, and that the Post-pliocene deposits of Scotland and Scan- 

 ditiavia almost precisely resemble those of Canada in the general 

 sequence of deposits. Since that part was published, additional 

 illustrations have been afforded by papers in the Geological Maga- 

 zine by Mr. Hull, and Mr. Mackintosh, by papers and discussions 

 on the Eskers of Ireland, at the meeting of the British Associa- 

 tion, and by an able monograph on the Estuary of the Forth, by 

 Mr. David Milne Home. Mr. Hull, who is a " Land Glacia- 

 list," arranges the deposits of the Drift Period in the British 

 area in the following three groups, in descending order, in accordance 

 with Prof. Ramsay's observations in England, and his own in 

 Ireland. 



1. Upper Boulder-clay, which he regards as " generally mar- 

 ine." In Canada, this is represented by the loose boulders and 

 partial boulder deposits of the Upper Saxicava Sand. 



2. Shelly marine sands and gravels belonging to the greatest 

 depression of the land, and representing our Saxicava Sand and 

 Leda Clay. 



3. Lower Boulder-clay, which represents the true or principal 

 Boulder-clay of Canada. This Mr. Hull attributes " chiefly to 

 land ice." 



In Ireland, it would thus seem that the principal sub-divisions 

 of the Post-pliocene can be recognized, and Mr. Kinahan has 

 described the remarkable ridges of gravel called eskers which run 



