ON INTERGLACIAL 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 /retreats of the glaciers are by n6 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 of 
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 of temperature, 
or if so only a very partial one, although the higher mountain 
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 British Drifts and the Inter-Glacial Problem,” 
p. 26. 
t Lecoq, H., “ Des Glaciers et des Climats.” 
