J5T. 75.] GLACIAL PERIOD. 333 



better for a younger man with more push and with the newer 

 petrological ideas to take the chair, especially as geology is now 

 to take its place amongst the subjects for examinations in 

 Science Honours. Although we shall miss you in Oxford I hope 

 we shall see more of you in London. ... I had a note a few 

 days since from Mr F. Latchmore of Hitchin, telling me he had 

 found bones of birds in the brick-pit. This is very interesting. 

 He sent me specimens], which I shall take to London. I also 

 had a note from Mr Prigg of Bury, telling me he had found im- 

 plements at all levels as in Kent. 



In writing the last (Glacial) chapter of Vol. II., I became more 

 convinced than ever of the mistake of Croll, and of the risk of 

 his lead to geologists. On the questions of geological or rather 

 glacial time I am becoming more heretical than ever. I do not 

 like to broach it abruptly in Vol. II., so shall probably send a 

 short paper to the Geological Society to ventilate the subject 

 beforehand. I am satisfied that if, instead of Croll's 1000, we 

 were to take 100, we should be nearer the mark, if not beyond 

 it. Still Croll's is a most attractive and valuable work. . . . 



The paper alluded to was a very important memoir 

 read in May to the Geological Society, its title being 

 " Considerations on the Date, Duration, and Conditions 

 of the Glacial Period, with Reference to the Antiquity 

 of Man." The author dwelt on the light thrown on the 



o 



duration of the Glacial Period by recent observations 

 on the movements of Greenland ice ; and the reading of 

 this paper gave rise to an animated discussion. His 

 views are expressed in the following letter to the friend 

 who shared his thoughts : 



J. PrestwicJi to J. Evans. OXFORD, isth May 1887. 



I don't know whether you remember when we were working 

 at the Somme Valley that my first impressions were that the St 

 Acheul beds were of glacial times, and that the excavation of 

 the valley was the work of post-glacial times. In working up 



