PHYSICAL CONDITIONS— POSTGLACIAL. 521 



either been stationary for a very long time, or else have under- 

 gone a recent submergence, the latter, as I believe, having been 

 the case. Be that, however, as it may, the existing floras of 

 Spitzbergen, Greenland, Iceland, and Fteroe, seem to establish 

 the fact of a postglacial land -connection with North-west 

 Europe, at a time when, as the evidence I have adduced leads 

 us to believe, the climate was more genial than at present. 

 This conclusion, it will be observed, is not in accordance with 

 the opinion of those who maintain that the cold of the Glacial 

 Period was due to the elevation of land in high latitudes. 

 But the fact is that the chief climatic vicissitudes of Glacial, 

 Interglacial, and Postglacial epochs appear to have been quite 

 independent of all movements of elevation and depression. 

 Sometimes intensely arctic conditions coincided with elevation, 

 but just as often the opposite was the case, as is proved by the 

 presence of deposits with arctic shells in Canada, Scandinavia, 

 and Scotland. On the other hand, while a genial climate now 

 and then concurred with a period of submergence, as during 

 the formation of the Postglacial shell-beds of Spitzbergen and 

 Norway, it is no less certain that mild and genial conditions 

 were frequently contemporaneous with a much wider extent of 

 land-surface in northern regions. 



It may be objected to the view of a great extension of land 

 having obtained in the Postglacial Period that the time required 

 for the geographical changes involved is greater than can be 

 supposed to have elapsed since the close of the Glacial Period. 

 To which it may be replied, first, that the data are insufficient 

 to enable us to say what amount of depression has taken place, 

 and, second, that we cannot calculate the rate at which the 

 submergence was effected. It may be that an elevation of 

 considerably less than 400 or 500 fathoms (2400 or 3000 feet) 

 would connect Greenland, Iceland, and the Fseroe Islands, with 

 Europe, and it may have taken 20,000 or 60,000 years, less or 

 more, to have brought about their isolation. We really have 

 no reliable data to go upon. The rate of 2J feet for each 

 hundred years assumed by Lyell for the elevation of a certain 



