I. 



The Fossil Plants of Canada as Tests of 

 Climate and Age.' 



IMPORTANT questions respecting the value of fossil plants as 

 tests of climate and geological age have arisen of late and have 

 been discussed in scientific periodicals and in special works, especially 

 in Seward's " Fossil Plants as Tests of Climate," and Lesquereux's 

 " Final Report on the Plants of the Dakota Group." A consideration 

 of what we have already learned on these subjects from the fossil 

 flora of Canada may therefore prove of service. 



In the first instance, it will be necessary to glance, by way of 

 contrast, at the condition of the vegetable kingdom in the Palaeozoic 

 period. In this part of the earth's history the problem is complicated 

 by the peculiar character of many of the plants, as well as by the 

 probability that the meteorological conditions were very dissimilar 

 from those now prevailing. We may say in general terms that a 

 flora of tree-ferns, giant lycopods and pines is akin to that of modern 

 oceanic islands in warm climates. This is true ; but the Devonian 

 and Carboniferous plants did not grow exclusively on oceanic islands, 

 but on continental areas of considerable magnitude. They flourished 

 also in all latitudes, from the polar region to the equator, and though 

 there are some generic differences in the plants of the period in the 

 Southern Hemisphere, yet these do not seriously affect the general 

 facies. There are characteristic Lepidodendroids, for example, in 

 the Carboniferous of Brazil and South Africa and Australia, and 

 though in the latter region there are certain ferns allied to those of 

 Mesozoic Europe, this is merely a local difference, not materially 

 affecting climate, and corresponding with the fact that the European 

 Mesozoic flora originated in the south. Nor does the doctrine of 

 homotaxis seriously affect the question. Each geological period was 

 sufficiently long to permit plants to migrate to every station they 



{} This article is extracted from the advanced proof of a paper " On the Cre- 

 taceous Plants of Vancouver Island," which will appear in the Transactions of the 

 Royal Society of Canada, and will end, for the present, the valuable series of papers 

 on the Mesozoic and Cainozoic plants of Canada, with which Sir William Dawson 

 has since 1882 enriched that publication. The present portion, which we have the 

 kind permission of Sir William to reprint, gives the general conclusions based on 

 the whole series. — Ed.] 



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