No. 1.] DAWSON — POST-PLIOCENE. 21 



dreAv of Loudon. I am also indebted to Mr. G. S. Brady for 

 determining the Ostracoda, to the Rev. H. W. Crosskey for op- 

 portunities of comparing specimens with those of the Clyde Beds, 

 and to Prof. T. R. Jones and Dr. Parker and Mr. Gr. M. Dawson 

 for help with the Foraminifera. 



The present memoir will, I am sure, be welcomed by all who 

 are engaged in the study of the subject to which it relates, if for 

 no other reason, because the Post-pliocene deposits of Canada 

 from their great extent and perfect development, are well fitted 

 to throw light on many of the controversies which are now agi- 

 tated with regard to these deposits. 



It may be proper here to indicate the nomenclature which will 

 be followed. When the whole oeolooical series is divided into 

 Primary, Secondary, and Tertiary, the deposits to which this 

 paper relates are usually named Post-tertiary or Quaternary. 

 These terms are, in my judgment, unfortunate and misleading. 

 If we take the relations of fossils as our guide, then, as Pictet 

 has well remarked, whether we regard the land or the sea animals, 

 there is no decided break between the Newer Pliocene and the 

 Post-pliocene, the changes not being greater than those between 

 the Pliocene and the older Tertiary ages. There is, therefore, 

 uo such thing in nature as a Quaternary time distinct from the 

 Tertiary, as the Tertiary is distinct from the Secondary. Where 

 therefore the terms Primary, Secondary, and Tertiary are used, 

 the latter should include the whole time from the Eocene to the 

 modsrn, inclusive, unless indeed the advent of man be considered 

 <an event of sufficient geological importance to warrant a separa- 

 tion of the modern from the Tertiary period. When the terms 

 Palaeozoic, jMesozoic and Kainozoic or Neozoic are used, then the 

 two latter terms cover perfectly the Post-pliocene as well as the 

 Eocene, Miocene and Pliocene. 



I would therefore include the Post-pliocene in the Neozoic or 

 Tertiary period and define it to be that geological age which 

 is included between the Pliocene and the Recent. From the 

 former it is separated by the advent of the cold or glacial^'' period, 

 and the accompanying subsidence of the land, as well as by the 

 disappearance of many species of animals and plants. From the 

 latter it is separated by the extinction of many mammalian 



* I use the term "glacial" in this paper in its general sense, as 

 including the action of floating ice as well as of land ice. 



