THE THAMES FROM GUILDEORD TO NEWEURY. 45 



surely should find debris from the Glacial Gravel in the valley of 

 the Loddon and its tributaries to the south, v^^hereas in fact this is 

 not the case. I have visited a number of localities with a view to 

 see how far south of the Thames in the Reading district such debris 

 have been spread. Plenty of quartz and quartzite-pebbles up to 

 4| inches in longest diameter were to be found in the gravel-pit 

 3^ miles from Reading on the Twyford road, and pebbles of a 

 similar kind occur near Earley Court. But even as near the Thames 

 as the gravel-pit by the railway ^ mile N.W. of Earley Station I 

 found no signs of Glacial debris, the gravel being composed of the 

 usual subangular flints, flint-pebbles, chert, and small quartz- pebbles 

 from the Southern Drift. I therefore feel forced to reject the 

 theory which assigns the contortions observed in clay-beds near 

 Wotingham to bergs or floes of ice which floated in waters that 

 filled the valley up to 240 feet above O.D.' 



In conclusion, the theory which I have adopted is that all the 

 gravels in the area here dealt with were formed after it had for the 

 last time risen above the sea. As soon as denudation began valleys 

 were formed and gravels spread out in them. By degrees the sides 

 of the valleys were destroyed, the gravel came to protect the ground 

 on which it lay, and so stood out as a hill.^ Then the gravel 

 itself was attacked and carried down by degrees to lower levels, 

 where it was again spread out and again protected the ground on 

 which it lay, becoming a terrace, a spur, or a minor plateau, and 

 thus the process has been repeated even to the present day. 



I also believe that the Glacial Gravels in the area dealt with 

 never extend more than a mile or two south of Reading, and that 

 none of the gravels in that area are of marine origin. 



Discussion. 



The Chairmais-, whilst complimenting the Author on his analysis 

 of the Southern Plateau-gravels, observed that there was at least 

 one point wherein Mr. Monckton agreed with his persistent oppo- 

 nent, Dr. Irving, viz., in the belief in their fluviatile origin. He 

 doubted if there was anyone present likely to contest that view. 

 As regards West Surrey such had always seemed to him the most 

 probable hypothesis, and he had pointed out how, through the opera- 

 tions of nature, the shallow valley-expanse of one period had become 

 the gravel-capped hill of another. The Southern Gravels under this 

 new test seemed, on the whole, still to retain their local origin 

 independent of Northern Drift and of foreign materials ; but he could 

 not help regarding with a certain degree of uneasiness the three 

 quartzose boulders on the table. Mr. Monckton had not, so far as 

 he gathered, ventured to draw any inference from their presence. 



^ Dr. A. Irving, Proc. Geol. Assoc. a^oI. xi. (1890) p. clx. 



^ See T. Rupert Jones, Proc. Geol. Assoc, vol. vi. (1880) p. 438 ; A. Irving, 

 ibid. vol. viii. (1883) p. 161 ; Monckton & Herries, ibid. vol. xi. (1889) p. 23; 

 W. H. Hudleston, ibid. vol. xii. (1891) p. 100. 



