458 Canadian Record of Science. 



there, as if America were the starting-point of that phase 

 of the vegetation, which, in its later developments, became 

 the flora of to-day on both continents. Again, the first 

 undoubted evidences of the flora of to-day, on any consider- 

 able scale, are found in the Leda clays of the Ottawa valley. 



The geological structure of Ontario, Quebec and Labra- 

 dor indicates that much of the areas included within their 

 boundaries has been dry land for vast periods of time prior 

 to the glacial epoch, and that within these areas are the 

 oldest portions of the continent. We can then readily con- 

 ceive that in tertiary times, this portion of the continent, 

 being even somewhat warmer than now, was the home of 

 vast numbers of the plants of the period. The American 

 species, now represented in Europe, we cannot in Canada 

 trace backward beyond the period of the Leda clays ; but it 

 is also clear that none of these identical species have as yet 

 been met with in the tertiary deposits of Europe, nor have 

 any, found in the Leda clays, been as yet observed in the 

 European post-tertiary deposits. Seeing, then, that North- 

 Eastern America, having been for so long a time dry land, 

 has always been an available home for vegetation, that the 

 Upper Cretaceous and the Eocene of America, in the resem- 

 blance of their flora to that of northern temperate America 

 of to-day, are older than the European Cretaceous and 

 Eocene, that it is only in later epochs in Europe that the 

 generic identity with North American plants became so 

 very distinctly marked, and that in Europe many of the 

 genera of the Pliocene, identical with those of to-day, have 

 since become extinct, there seems a possible presumption, 

 quite apart from that derivable from their present range, 

 that some of these identical European and American plants 

 may be older in America, and, being chiefly northern tem- 

 perate in range, may have originated in northern temperate 

 America. 



There are other interesting questions in this connection. 

 The rounded or smoothed, often striated, character of the 

 rocks, and the presence of the boulder clay and its accom- 

 panying boulders, would, if we admit the action of glaciers 

 in the work, appear to prove the higher altitude of, per- 



