part 2] CHALK MARLS IX THE SOMME YALLET. 143 



North Devon. If this were the case, the position of the synclines 

 at the surface anterior to denudation might well have coincided 

 with the streams. 



The Author said, in reply to Prof. Kendall, that he realized 

 that Chalk yielded water only from small cracks and fissures, but 

 these were so numerous in the Chalk (in comparison with those in 

 the marls), that, while the one was impervious to water, the other 

 behaved as a porous mass. In regard to the folds of the Chalk 

 on any proposed site for the Channel Tunnel, it should be re- 

 membered that the majority of the borings were situated near the 

 zone of fighting, and it was therefore lucky for us that the informa- 

 tion was scanty in the Calais district. 



In reply to Dr. Evans, the Author said that the suggestion 

 which was made in the paper that the Tertiary syncline was 

 actually situated north of the Cretaceous one was intended to 

 account for the marked difference in the position as given by 

 M. Dollfus and that shown by the recent borings. 



