.■376 THE PLIOCENE DEPOSITS OP CORNWALL. [vol. Ixxvili, 



.seemed to the speaker that it would be very useful if the Author 

 would include in his paper an account of the method of sampling 

 adopted, so that other workers might be able to obtain results 

 that were fairly comparative. 



With regard to the mineral composition of the sediments 

 described, it was perhaps worth while to enquire whether the rela- 

 tive amounts of such minerals as garnet, staurolite, and kyanite, 

 which were all metamorphic minerals in the ordinary sense, and 

 might have emanated from the same ultimate source, were in any 

 way connected with differences in chemical stability. Such 

 differences had a good chance of asserting themselves where the 

 proximate derivation was from other sediments, and where con- 

 sequently the minerals had suffered repeatedh^ from the action of 

 processes incidental to detrital sedimentation, possibly under a 

 wide range of climatic variation. 



Dr. J. W. Evans thought it improbable that the relative level 

 -of land and sea changed to the same extent throughout the area 

 concerned. He did not believe that material could have been 

 transported from the north-east by coastal wave-action. On the 

 northern coast of Devon and Cornwall it was the north-westerly 

 winds that produced the most important transporting action, and 

 the movement was from south-west to north-east, not vice versa. 

 If the kyanite had travelled from the Lower Grreensand of the 

 neighbourhood of Devizes, it must have been by means of river- 

 action, when the Bristol Channel was a tract of alluvium and 

 Devon and Cornwall were at a relatively low level. 



Mr. II. B. Newton declined on palseontological grounds to 

 accept a Pliocene age for the St. Erth deposits. His own studies 

 (see Journ. Conch, vol. xv, 1916) of the shells from those beds 

 were all in favour of their Upper Miocene horizon, and as exactly 

 the same facies was apparent among the Lenham mollusca, he was 

 of opinion that the St. Erth and Lenham Beds were of contempo- 

 raneous origin. He mentioned the occurrence of similar species 

 of shells in the Grourbesville deposits of Normandy which had 

 been described by M. Gustave Dollf us (Bull. Soc. Geol. Normandie, 

 1880, and C. R. Assoc. Eran9. Av. Sci., Cherbourg, 1906, 

 pp. 358-70), and referred to the Redonian stage of the Miocene, 

 which is considered the equivalent of the Upper Vindobonian 

 horizon of Europe. The speaker was also of opinion that the 

 palseontological evidence proved that the St. Erth as well as the 

 Lenham deposits represented fragmentary remnants of the Conti- 

 nental Miocene development, which extended from Holland, Den- 

 mark, Northern Germany, and Northern France. 



The Author, in reply to Prof. Boswell, said that it appeared to 

 him unlikely that the staurolite could have come from the north- 

 east, in view of the absence of kyanite from St. Keverne ; if both 

 the minerals had been derived from the north-east, kyanite should 

 have penetrated at least as far as the staurolite, and it should 

 appear with the latter at St. Keverne, which is actually not the 



