ON INTEEGLACIAL EPOCHS 45 



argue, has left no traces of animal or plant life in all the 

 numerous deposits which have been examined. 



The whole conception of these interglacial phases of the 

 Glacial Epoch has given rise to a good deal of animated 

 discussion. Professors Chamberlin and Salisbury have 

 adopted Professor James Geikie's view that there were 

 six great advances and retreats of the ice -sheets, sepa- 

 rated by five interglacial intervals, during which a mild 

 climate prevailed. But the evidences for these alternate 

 advances and /tetreats of the glaciers are "by no means ad- 

 mitted as valid by all geologists. Some maintain that there 

 were only three such great advances and retreats. Others 

 admit only two of them. Some authorities disbelieve alto- 

 gether in mild interglacial phases, and admit only one ad- 

 vance followed by a gradual retreat of the ice. Even after 

 studying the Toronto clays, which Mr. Lamplugh * acknow- 

 ledges impressed him strongly as affording the kind of evi- 

 dence which he has sought in vain in Britain, he is still 61 

 opinion, as expressed in his address to the Geological Section 

 of the British Association, that there is no proof of mild inter- 

 glacial epochs, nor even of one such epoch. 



My own conclusions as to the nature of the Glacial Epoch, 

 and the causes that produced the glacial clays, being almost 

 entirely based on the evidence derived from the past and pre- ; 

 sent fauna and flora, I have no hesitation in agreeing with ' 

 Mr. Lamplugh's views. There is no biological evidence in 

 North America in favour of one or more interglacial phases. 

 Everything moreover points to the fact that during the so- 

 called Glacial Epoch there was no diminution ofjemperature, 

 or if so only a very partial one, although the higher mounfoin 

 ranges were covered by glaciers. In many parts of North 

 America there was probably a higher temperature during the 

 Ice Age than obtains at present. The first to advocate the 

 idea of a higher mean temperature being compatible with a 

 greater extension of glaciers was, I think, Professor Lecoq.f 



Much more recently a similar theory was very ably main- 



* Lamplugh, G. W., " On Britisli Drifts and the Inter-Glacial Problem," 

 p. 26. 

 t Lecoq^, H., " Des Glaciers et des Olimats." 



