30 GKAYELS SOUTH OP THE THAMES FEOM GTJTLDFOED TO NEWBTJKT. 



' Geology of London '. ^ I also wish to express my thanks for 

 very great assistance in the collection of the facts recorded in this 

 paper to Mr. E. S. Herries and to Messrs. J. H. Blake and F. J. 

 Bennett, of the Geological Survey. 



In my comparison of different gravels I have given a description 

 of the general appearance and nature of the stones which form them, 

 and also in several cases an analysis of the smaller material, mean- 

 ing thereby such as passes through a riddle of half-inch mesh and ia 

 retained in one of yl^-incli mesh. It is not here asserted that this is 

 a thoroughly satisfactory way of comparing gravels, but it brings out 

 the distinction between the different classes quite sufficiently for my 

 present purpose. 



I. The Southern Drift. 



Class 1. Upper Hale type. 



The Drift edition of Sheet YIII. of the Geological Survey map 

 having been very recently published, no sketch-map is given for this 

 part of the paper. The gravels which I should assign to the Southern 

 Drift are all included in the " Hill Gravel of doubtful age and 

 origin" coloured red, though in places the colouring is extended 

 farther into the valleys than I should be inclined to carry it, and 

 includes some patches which I should call gravels derived from the 

 Southern Drift. The Long Valley, Aldershot, the northern end of 

 the Fox B-ills, and the northern side of Hartford Bridge Flats are 

 instances. 



In Class 1 may be placed the plateau which, under the names Hungry 

 Hill, Caesar's Camp, and Beacon Hill, stands out high above the Long 

 Yalley, Aldershot. On its southern edge is the village of Upper 

 Hale, not marked on the Geological Survey map, where there are 

 very extensive gravel-pits. This hill is shown in the diagrammatic 

 section, fig. 1, which is along nearly the same line as S. Y. Wood's,^ 

 and parallel to Prof. Prestwich's.^ The first-named author calls 

 the gravel " gravel of the greatest submergence." The plateau not 

 only overlooks the country to the north, as shown in fig. 1, but 

 also the Wealden area to the south,^ It varies from 615 to about 

 470 feet above O.D. I should mention that the levels in this paper 

 are taken from the Ordnance maps, or calculated as correctly as 

 lay in the writer's power from levels given on those maps. In 

 many cases thanks are due to Mr. J. H. Blake for them. The deposit 

 has been described by Prof. Prestwich ' and by Dr. Irving.^ To 

 their description the following is supplementary. The gravel is not 

 usually stratified, but here and there a rough stratification is seen 

 near the bottom, of which one instance is given in fig. 2. It is in 



^ Mem. Geol. Surr. 1889. 



- Quart. Journ. Geol. Soc. vol, xxxvi. (1880) pi. xxi. fig. 3, line B. 



3 Ibid. vol. xlvi. (1890) pi. vii. 



4 See Mem, Geol. Surv. vol. iv. (1872) p. 376. 



' Quart. Journ. Geol. Soc. vol. xlvi. (1890) p. 161. 

 « Ibid. p. 559. 



