iy8 SURVEY OF THE SNOWDON REGION CHAP, v 



A week after the reading of this essay the follow- 

 ing entry occurs in the diary. * Went over my Welsh 

 glacier-maps at night. Walked up each valley with 

 my mind's feet, and took Logan with me. He said at 

 the close that he thought I had proved my case, but 

 that before publication I had better look at a few 

 points again.' Whether it was this advice of the 

 veteran Canadian geologist, or the criticism at the 

 Society, or his own mature reflection that determined 

 him, he withheld the publication of the paper for more 

 than a year, and then issued it with a slightly altered 

 title. 1 The chief point insisted on in the paper was 

 the fact that the so-called glacial period embraced two 

 distinct glaciations : one widespread and prior to the 

 deposition of the Drift ; the other local in valleys and 

 later than the Drift. 



A subsequent meeting of the Society is thus de- 

 scribed : * Murchison had a paper on the Denudation 

 and Drift of the Weald of Sussex. When the debat- 

 ing came, Lyell first spoke indifferently, unable to 

 overcome the difficulties, but evidently feeling that 

 Murchison's catastrophic solutions were the greatest 

 difficulties of all. Then followed Sharpe, who said that 

 one would suppose from M.'s reasoning that elephants 

 were marine, instead of terrestrial animals. Then came 

 Mantell, who, in a most eloquent speech, asked, if the 

 great mammifers were annihilated by this catastrophe, 

 how is it that their bones are always found scattered 

 and in fragments ? Would not the ligaments and skin 

 keep them at least so far together that we would find 

 the principal parts of the skeleton near? Then 

 followed Forbes on the same tack, then Dr. Fitton, 



1 < On the Superficial Accumulations and Surface-markings of North Wales, 5 

 Quart. Journ. Geol. Soc. viii. (1852), p. 371. 



