190 



ME. H. w. monckto:n ois^ some geavels [^ay 1898, 



the top of the stone there was 2| feet of gravel and surface-earth. 

 The gravel above and at the sides of the stone showed scarcely any 

 sign of stratification. There can thus be no doubt that this large 

 stone was moved during the deposition of the gravel, but though 

 waterworn it retains its angular form to a great extent, and it 

 seems to me that the position of this sarsen, together with the con- 

 tortions in the gravel, furnishes evidence of the presence of ice in 

 the river by which the gravel was laid down. 



For many years gravel has been worked for roads at Penny Bill, 

 near Bagshot. The level is 400 feet above Ordnance datum, and 

 the hill is practically part of the Chobham liidges plateau. The 

 sections frequently show that the gravel is to a great extent of an 

 unstratified and mottled character. In August last I saw a small 

 sarsen, 2 feet from the surface of the ground and 2| feet from 

 the bottom of the pit, the whole side of the pit being formed of 

 gravel with scarcelj' a sign of stratification. 



The Rev. Dr. Irving has described a completely unstratified 

 gravel at this same level (400 feet above Ordnance datum) at Broad- 

 moor, which is on a part of the plateau of the Easthampstead Plain, 

 and evidently contemporaneous with the gravel that I have beeu 

 describing on the adjoining Chobham Ridges plateau. Dr. Irving 

 suggests that it may be a glacial deposit of Pliocene age.^ 



Through the kind- 

 Fig. 4. — Section in Windsor- Ride Gravel-pit, 



Camherley (reproduced, by permission, 



from a drawing made on the spot by Prof. 



T. Rupert Jones, May 24:tJi, 1863J. 



ness of Prof. Eupert 

 Jones, F.B.S., I am 

 able to reproduce 

 a sketch (fig. 4) 

 taken by himself in 

 1863, which repre- 

 sents an irregularly - 

 shaped block of 

 brown sand 6x3 

 feet in gravel. Prof. 

 Rupert Jones con- 

 siders that this block 

 was probably frozen 

 when embedded in 

 the gravel, and that 

 it is consequently 

 evidence of the pre- 

 sence of ice in the 

 waters by which the 

 gravel was deposited. 



N. 



i— White (discoloured) sand and gravel, with ablack 



irregular line at the bottom. 

 ii = GrraTel. 



On the same plateau as these examples are numerous instances 

 of well-stratified current-bedded gravels. We have therefore ex- 

 amples of stratified, contorted, unstratified, and mottled gravel, all 

 on the same plateau, and all, I should say, of the same age. 

 Moreover, these features are present in gravel at all sorts of levels, 



Quart. Journ. Gleol. Soc. yoL xlvi (1890) p. 561, note. 



