MODIFICATION OF THEORY EXAMINED. 97 



o-o on increasing vear by vear till it covered the whole 

 of Scotland, Ireland, and Wales, and much of England. 

 Dr. Croll and Dr. Geikie answer without hesitation 

 that it would. Sir Charles Lyell maintained that it 

 would only do so when geographical conditions were 

 favourable." * Here we have a complete misappre- 

 hension of the relation between Sir Charles Lyell's 

 views and mine ; for I would certainly maintain (and, I 

 presume, Dr. Geikie also) as emphatically as Sir Charles 

 could do, "that it would only do so when geographical 

 conditions were favourable." For undoubtedly, accord- 

 ing to the theory advocated in ' Climate and Time,' no 

 glacial epoch could result without geographical condi- 

 tions suitable for the operation of physical agencies ; 

 and this is virtually what Sir Charles maintains. The 

 glacial epoch resulted during the last period of high 

 eccentricity because the geographical conditions suit- 

 able for the effective operation of the physical causes 

 then existed. 



6. It is assumed in c Climate and Time' that, with 

 the exception of those resulting from oscillations of 

 sea-level, afterwards to be considered, the general 

 distribution of sea and land, and other geographical 

 conditions, were the same during the glacial epoch as 

 they are at present.-)- Consequently, in accounting for 

 the glacial epoch I had only to consider the effects 



* "Island Life," p. 136. 



f Prof. J. Geikie, however, believes that during early Postglacial 

 times a considerable change in the physical geography of the Xorth 

 seas took place (see " Prehistoric Europe," chap. xxi.). In order to 

 account for the floras of Greenland, Iceland, and the Faroe Islands, 

 he thinks a land connection must have existed between these places 

 and Scandinavia. For reasons which will be stated in a future 

 chapter I am somewhat doubtful on this point. There is, I think, 

 an important agent overlooked in the question of the distribution of 

 Arctic flora and fauna. Prof. Geikie, however, does not believe that 

 the climatic condition of that period was in any way due to this change. 



H 



