^^^' 55-] PEBBLES OP SCHOKL-SOCK IN DRIFT-DEPOSITS. 221 



courses — one along a peneplain west to east from Dartmoor, the 

 other from south-west to north-east across England. The pebbles 

 are absent from the Weald and from the district around Bagshot^ 

 from the Hampshire Basin and its bounding hills (with the ex- 

 ception of the extreme south), and from the highest and presumably 

 oldest gravels north of the Thames. 



DiscirssioN (on the two eoeegoing Papers). 



Mr. C. Beid pointed out that irregular decalcification or settle- 

 ment in gravels tends to cause the longer axes of the stones to 

 become vertical, and that this vertical position, therefore, must not 

 be taken as evidence of glacial action. "With regard to Mr. Salter's 

 specimens of schorl-rock, he was sorry to see that the Author still 

 insisted on confounding gravels of Eocene age, at Haldon, Hardy's 

 Monument, and Dorchester, with much later Drift-deposits of other 

 areas. 



Mr. Matley considered Mr. Salter's record of the distribution of 

 schorl-rock pebbles more valuable than the theory put forward to 

 account for that distribution. Schorlaceous pebbles occurred not 

 uncommonly in the Birmingham Drift, as shown by some specimens 

 which the speaker exhibited, but it did not need a peneplain from 

 the South-west of England to bring them to the Midlands, for they 

 were clearly derived from the Bunter Conglomerate. Mr. Waller had 

 described (and his microscopic slides were on the table) the petrology 

 of tourmaline-bearing pebbles both from the Bunter and the Midland 

 Drift. Similarly, the pebbles farther south, instead of proving a 

 north-eastern peneplain, were Bunter pebbles, which may have ori- 

 ginally come from Cornwall but had not seen their parent-rocks since 

 Triassic times. The Author's own statement bore this out, when he 

 said that, while schorl-rock pebbles were absent in the Wealden 

 area, they occurred, associated with northern rocks, at Kingston 

 Hill, Dartford Heath, and Crayford. 



Mr. H. W. Monckton, referring to the paper by Mr. Salter, first 

 expressed a doubt as to the relationship between the gravel at the 

 Hockett, 350 feet above the sea, and the valley or gap at Goring. 

 Secondly, if he understood aright, the Author accounted for the 

 presence of the schorl-rock pebbles in Suffolk and Essex as follows : 

 1st. They had been carried by river-action from the far south-west 

 to, say, the Bedford district ; 2nd. They had been subsequently re- 

 drifted through gaps in the Chalk into Suffolk, etc. If that were so, 

 the speaker thought that there should be remains of the deposit 

 near Bedford, formed during the first of these stages, and he asked 

 whether any such remains had been found. Thirdly, the speaker 

 had himself found schorl-rock in the Bunter of Nottinghamshire ; 

 and he asked whether the Author could point to any distinction 

 between the schorl-rock pebbles of the Suffolk, etc. gravels and those 

 of the Bunter Beds. 



Mr. E. S. Herries thought that, before Mr. Salter's theory could 

 be accepted, he ought to show that the specimens of tourmaline-rock 



