22 THE CANADIAN NATURALIST, [Vol. 



VI. 



forms aud by the establishment of our continents at their present 

 elsvation above the water and with their present fauna and flora 

 and drainage systems. In Canada the absence of the Pliocene 

 deposits and the immediate superposition of the Post-pliocene 

 on the Palaeozoic formations, remove all difficulty on the subject 

 of the beginning of the period. The line of separation between 

 the Post-pliocence and the recent, especially in Western Canada, is 

 less distinct; but in Eastern Canada the upper part of the Post- 

 pliocene is always marine, while the recent deposits are land aud 

 fresh-water. 



With regard to the subdivisions of the Post-pliocene in Canada, 

 if we confine our attention to the clearly marked marine and 

 glacial beds of the lower part of the St, Lawrence Valley, we 

 have no difficulty in establishing the following divisions, suggested 

 in my paper of 185*T : 



3. Saxicava Sand, shallow-water sand and gravels, equivalent 

 to the Champlain and Terrace epochs in part of Dana, to 

 the modified drift of Hitchcock in part, to the Tertiary 

 sands of Capt. Bayfield ; and to the Upper fossiliferous 

 sands and gravels of Scotland and Scandinavia. 



2. Leda Clay, moderately deep-water clays, equivalent to lower 



part of Champlain epoch, Dana, and Tertiary clays of 

 Bayfield. Fossiliferous Clays of Scotland and Scandi- 

 navia. 



3. Boiddei'-Clay.—YisiYd clay or sometimes sandy clay or sand, 



with stones and boulders, and not distinctly laminated. 



Equivalent to Glacial clays of Dana and unmodified 



drift of Hitchcock, Till aud older Boulder-clay of 



Scotland and Scandinavia. 

 In Lower Canada these three deposits can often be seen in 

 actual superposition, and the order is invariable. In some places 

 all contain marine shells, in others these are limited to the upper 

 part of the Leda clay or the lower part of the Saxicava sand. 



In Western Canada, around the great lakes, are extensively 

 distributed beds of clay and gravel, which have been described in 

 the Report of the Geological Survey, and which have afl"orded fresh- 

 water and land remains only. Of these the Algoma sand and 

 Siugeen clay and sand may possibly correspond in age to the 

 Saxicava sand, and the Erie clay to the Leda day. This iden- 

 tification is, however, uncertain, as the marine Leda clay has been 

 traced up no further than the vicinity of Kingston, on the St. 



