NO. 6 PAST CLIMATE OF NORTH POLAR REGION BERRY 5 



The Spitzbergen flora comprises 12 fernlike plants. 5 pteridosperms, 

 I arthrophyte, 25 lepidophytes, i cordaites (wood), and 15 of un- 

 certain botanical affinities. Stigmarias and various roots occur in 

 place beneath the coal seams, showing that the vegetation was pre- 

 served essentially in place ; and Lepidodendron stems have been col- 

 lected up to 16 inches in diameter. There are no peculiar Arctic types 

 in this most extensive known Culm flora nor are there any genera 

 that are not common to floras of the same age from lower latitudes. 

 The single wood, Dadoxylon spctshcrgcnsc Gothan, fails to disclose 

 any seasonal growth changes, which might be expected to result from 

 the Arctic night. No other traces of the Cordaitales other than this 

 wood have been discovered here, which leads Nathorst to suggest 

 that the wood may have been carried 1)y currents from some more 

 southern clime, where also the woods fail to show growth rings. 

 This may be true, but on the other hand there is great specific varia- 

 tion in the degree to which growth rings develop in existing conifers, 

 as Antevs has pointed out, and they tend to be absent under fairly 

 uniform conditions of humidity. That this is an individual trait of 

 this particular species and is probably without climatic significance is 

 shown by the presence or alxsence of rings in Devonian and Mississip- 

 pian Dadoxylon woods from lower latitudes. For example, Dadoxylon 

 beinertiaiiiiiii Endlicher from Silesia, Dadoxylon TcJiicliatclicffiaiiiiiiit 

 Endlicher from Russia, and Dadoxylon vogcsiacnui Unger from the 

 Vosges, all of the same age as the Spitzbergen species, show distinct 

 seasonal rings, but other contemporaneous European species fail to 

 show them. 



I cannot see any very conclusive indications of climate in these 

 Lower Carboniferous floras, other than the fact that they extended 

 in places to within 10 degrees of the pole. Palustrine types pre- 

 dominate as in the case of the Devonian, and more than half the 

 known forms arc Lepidophytes which we have reason to ])elieve show 

 little response to temperature. Sphenophyllums are entirely wanting 

 in Spitzbergen, but are found farther north in Greenland and occur 

 on Bear Island, so that their absence in Spitzbergen is merely an 

 accident of preservation or discovery. In general Arthrophytes are 

 much rarer in the far north than in middle latitudes at this time and 

 the same seems to be true of a number of genera of large fronded 

 fern-like plants, which is taken to indicate differences due to latitude. 



TRIASSIC 



Triassic plants except in the latest or Rhaetic stage are scarcely, 

 if at all known in the north polar region. There is a species of 



