216 PKOCEEDINGS OF THE GEOLOGICAL SOClEXr. [Feb. 24, 



Mr. J. W. Plowee objected to all the fossils attributed to the 

 Postglacial period being regarded as synchronous, and to the cave- 

 and river- deposits being classed together. 



Mr. Evans hoped that at some time a chronological arrangement of 

 British caves might be proposed. He mentioned the discovery of a 

 palaeolithic flint implement in a brickfield at Highbury, and argued 

 against the lower-level deposits of the Thames valley being regarded 

 as more ancient than the higher. 



Mr. ToPLEY called attention to the absence of river-gravels and 

 caves in the Silurian region of Wales and of the North, which was 

 owing mainly to the absence of limestone adapted for the formation 

 of caves and of material for gravels. 



Prof. Eamsat argued that caves such as those in which mam- 

 malian remains occur must have existed in preglacial time, and 

 therefore that it would be strange if none of those explored con- 

 tained preglacial remains. He was not satisfied as to the cause of 

 the Thames forming a line of demarcation marking the absence of 

 Glacial deposits. It could only be accounted for in his mind by the 

 valley of the Thames having been entirely excavated since the 

 Glacial period, though he acknowledged this was a bold speculation. 

 He had always regarded the Thames-valley deposits as postglacial. 



Mr. Whitaker thought that the brick-earth of the lower part of 

 the Thames valley was one of the later deposits in that valley, and 

 therefore Postglacial. Beneath the Corhicula-hed of Crayford there 

 were shells of some of the common living species of the neighbour- 

 hood. He saw no such extreme difficulty in the excavation of the 

 Thames valley since the deposition of the Boulder- clay. 



Mr. GwYisr Jeffreys mentioned the Helix ruderata and H. fruticum 

 as being instances of shells of northern character occurring in the 

 Thames valley at Ilford. No shells of an arctic or boreal character 

 occurred in the South of England; so that it would appear that it had 

 not been submerged during the Glacial period. 



Mr. Peestwich was glad to find that the opinion of the Thames- 

 valley deposits being Postglacial was gaining ground. He called 

 attention to the existence in Prance of river-gravels belonging to an 

 earlier period, such as that near Chartres ; so chat such might exist 

 elsewhere. He could not reconcile the occurrence of Hippopotamus 

 so far north as Leeds with its annual migration, as had been sug- 

 gested. 



Mr. Godwin-Austen agreed with the view of the author of the 

 * Eeliquiee Diluvianae,' that the animals whose remains occur in 

 caves lived prior to the submergence which filled the caves, or, in 

 other words, to the Glacial period. He thought that it was impos- 

 sible for all the animals whose remains occurred in the Piver-gravels 

 to have occupied the land surface at the same time. He considered 

 that English geologists were too prone to argue from phenomena 

 confined to this country. A long island must have existed where 

 now is the South of England at the Glacial period ; but he thought 

 that at that time all animal life must have ceased there. If so, our 

 divisions of time could not apply to the Continent, where no such 

 extreme changes in conditions took place. 



