118 MR. CLEMENT EEID OX A PROBABLE [^ a }" I 9°4? 



rocks, but possibly of later date, in the South of Ireland. If the 

 Tertiary age of the "Wolf Kock were proved, then it must belong- 

 to a distinct petrographical province, as all other Tertiary igneous 

 rocks in the British area were free from nepheline. 



Mr. H. W. Monckton said that the decayed flint-pebbles exhibited 

 by the Author were very unlike the black and singularly well- 

 preserved flint-pebbles characteristic of the Eocene pebble-beds of 

 the London Basin. At Highcliff, near Christchurch, however, there 

 were, no doubt, decayed flints in a Bracklesham pebble-bed. 



Mr. P. E. Kendall said that the origin of the superficial deposits 

 of Cornwall had given rise to much speculation and controversy. 

 He did not think that the Author had offered very conclusive proofs 

 of the age of the deposits, but he could not altogether agree with 

 the previous speaker. The most corroded flint-pebbles that he had 

 ever observed were from an excavation in Blackheath Beds at Mile 

 End. They were actually pulverulent, yet distinct and charac- 

 teristic. He had not understood the Author to imply that all the 

 pebbles in Eocene deposits were corroded, but that such altered flints 

 were characteristic of Eocene rather than of Pleistocene gravels. 

 The paper constituted a bold attempt to solve the problem of the 

 widely-extended deposits of subangular pebbles in Southern England 

 and Southern "Wales. He did not think that the phonolite of the 

 "Wolf Hock had any very direct bearing on the question. Prof. Cole 

 had pointed out that the volcanic rocks of Ardtun, in Mull, were 

 exceedingly rich in alkalies, and further search would possibly 

 reveal the presence of phonolites there. 



Dr. A. E. Salter asked whether the Author had detected fragments 

 of any other materials, besides Greensand- chert and flints, similar 

 to those found in old river-gravels, derived from the Dartmoor area 

 to the east, as, for example, at Hardy's Monument (Dorset). The 

 speaker had searched in vain some few years ago for evidences of a 

 western drainage from Dartmoor, in Cornwall. On Crouza Down, in 

 the Lizard district, at an altitude of about 360 feet above sea-level, 

 is an extensive deposit of gravel, but the rolled fragments consist 

 mainly of quartz. He agreed with previous speakers in doubting 

 the advisability of relying upon the degree and manner of weathering 

 of flints as evidence in proving the Eocene age of a deposit. 



Mr. H. B. "Woodward, adverting to the striated stone from the 

 Scilly Isles exhibited by Mr. Barrow, asked whether the Author 

 could not account for the transport of the accumulations of flints 

 by some form of ice-action. 



Mr. Barrow remarked on the curious distribution of pebbles: in 

 the Scilly Isles, some of them being found up to the highest levels 

 on St. Martin. The noteworthy hollow which extends from St. 

 Ives to Mounts Bay is a phenomenon repeated over and over again 

 in the Scilly group. 



Mr. \Yhttaker objected to calling most of the stones exhibited 

 ' pebbles/ as they hardly deserved that description. Despite the great- 

 mass of the pebbles in the Eocene of the London Basin being black 

 flint, there were exposures where decomposed flints were found, and 



