Yol. 54.] OF THE BAGSnOT DISTRICT. 193 



plateaux above it, and to the gravel-covered flats near the Thames 

 below. Now, my point is that all are river-gravels, and the question 

 arises, if I am right in this view, is there anything to show that the 

 sea invaded this district at any time between the deposition of the 

 oldest and the newest gravels ? 



Dr. Irving has brought forward an example of contorted stratifi- 

 cation at a level of 240 feet above Ordnance datum near Wellington 

 College, and he attributes the contortions to ' the action of bergs 

 or floes of ice which floated in the waters that then filled the 

 valley up to about this level.' ^ Mr. Hudleston has, however, 

 attributed a very similar example of contortion to a sliding mass 

 of neve or indurated snow.^ 



On the whole, therefore, I venture to submit that we have no 

 evidence of the presence of the sea in this district during the Drift 

 period. There is, however, as I hope I have shown, ample evidence 

 of ice-action, and this evidence is more or less present in the gravel 

 at all levels, so that I am led to think it probable that the gravel 

 of this part of England practically coincides in age with the dura- 

 tion of the Glacial Period — using that term in a wide sense, so as to 

 include the period where indications of approaching cold appear in 

 (or even before the date of) the Cromer Forest Bed.^ 



DiscTJSsioi^r. 



Mr. Clement E,eid asked why the gravelly sarsen- stones exhibited 

 might not be of Eocene date. They were discovered loose on the 

 surface, but were similar to gravelly sarsens undoubtedly of Eeading 

 and Bagshot ages found in Dorset. Was there any known instance 

 of the formation, in this country, of a siliceous conglomerate in a 

 deposit newer than the Oligocene? With regard to the trans- 

 portation of large angular masses of flint and sarsen, he remarked 

 that when the gravels of the Chobham plateau were being deposited, 

 the area must have been dominated by land of considerably greater 

 height within a short distance. Perhaps slow soil-cap movement, 

 like that of Patagonia, may have helped to transport the blocks 

 down gentle slopes. It seemed scarcely necessary to postulate the 

 action of river-ice at that height. 



Mr. Whitakee said that all agreed that great unworn flints could 

 not have been rolled down, by streamy for any great distance. He 

 had seen flint-pebbles in East Kent made in a chalk-pit, artificially 

 and very expeditiously, by washing in puddle-pits. As to sarsen- 

 stones, there was no need to invoke very distant transport, as they 

 may come from various Tertiary deposits. It was very singular 

 that in the Chalk tract of the London Basin sarsens occur to the 

 greatest extent in that part where, from the westerly thinning of 

 the London Clay, the Bagshot Beds come within little vertical 



^ Proc. Geol. Assoc, vol. xi (1890) p. clx. 



2 Quart. Journ. Geol. Soc. vol. xlii (1886) p. 169 & fig. 8. 



' H. B. ^^^oodward, ' Geol. of England & Wales,' 2nd ed. 1887, p. 481. 



