320 DAWSON AND PENHALLOW — PLEISTOCENE FLORA. 



( >ne other poinl remains to be illustrated with reference to the local origin 

 of the vegetable remains. Where these consist of trunks and branches and 

 are contained in the bowlder-bearing beds, they may, like those found under 

 similar conditions in the arctic, be drift-wood, derived Prom great distances 

 and in a condition of partial submergence of the continent. The facility for 

 such distribution must, in the Pleistocene age, have been greater than it now 

 is in the arctic where there is, according t<» the testimony of voyagers, not 

 only a great quantity of such material on tin- s1k.iv, but mixed with clay and 

 bowlders at Bome distance inland. There is reason to helieve that through- 

 out Canada such drift-wood may he found here and there in both the upper 

 and lower how hhr deposits. 



Where, however, we have leaves and other perishable parts, and especially 

 where there are peat beds and peaty soils, or where the vegetable remains 

 are associated with fresh-water shells, the case is different. We have in 

 these circumstances evidence of the local flora, ami cannot doubt that the 

 climate must have been sufficiently mild to permit the growth iii situ of the 

 plants whose remains are found. So far as we know at present, evidence of 

 this kind applies, //;.-/, to the land surfaces anterior to the earlier bowlder 

 deposit; secondly, to the swamps and upland.- of the Leda clay and "inter- 

 glacial " period; and, thirdly, to the early modern time succeeding the upper 

 bowlder drift. The plants specially referred to in the following notes are, 

 90 far as known, those of the second of the above period-. 



In conclusion, it is deserving of notice that the plants indicated in Pro- 

 fessor Penhallow's lists are not an arctic assemblage, but rather a part of 

 the cold temperate Mora. They scarcely indicate BO much refrigeration as 



that evidenced by the plants from British interglacial beds a- described by 

 Carruthers.* Further, as the species referred t<> are either local or drifted 

 by Btreams from the north, it follow- that the arctic flora must have existed 



to the north of the Canadian localities referred to. This accords with the 



fact proved by arctic explorers and the officers of the Geological Survey of 

 < !anada,1 that in the glacial period striation and driftage of bowlders point to 



drift toward the arctic hasin as well as toward the south. Thus, when these 

 plant- flourished in Canada, there must have been open water and a land 

 flora in the arctic basin —condition-, of course, altogether incompatible with 



the existence of a polar ice-cap, though not inconsistent with th icurrence 



of glaciers in the more elevated districts or those « led by the cold arctic 



currents. That the climate was colder, locally at least, in the period of the 

 bowlder clay need not he doubted, but there i- reason to believe that the 

 general different f temperature in the BO-called interglacial period as com- 

 pared with that of the how Ider clay ha- been greatly exaggerated. 



on Report, U - . p| i, "Geological Hlatory ol PI i 



leology ol Northern Pai ida, Report Geological Survey of Canada, 1887, 



