36 



MK. H. W. MONCKTOJSr 0^ THE GEAVELS SOUTH OF 



quite near the bottom. The upper part is frequently much con- 

 torted, masses of sand running into it in a most fantastic manner to 

 (5 or 7 feet from the surface of the ground. In composition the 

 gravel resembles that of the great plateau. 



Einchampstead Eidges, to the north of Hartford Bridge Elats and 

 about the same altitude, 300 to 333 feet above O.D., is also capped 

 by gravel which, though not mentioned by Prof. Prestwich, doubt- 

 less belongs to his Southern Drift. The compositipn is similar to 

 that of the Hartford Bridge Plats gravel, and it is no doubt of 

 nearly the same age. 



I have now dealt with all the large patches of Southern Drift in 

 the Bagshot Heath country, but there is still a series of hills capped 

 with gravel which resembles that of the Chobham Eidges plateau, 

 but contains a far larger proportion of chert. Thus the hills at 

 Windlesham named Pibs Down and Long Down (Pears Hill), 310 

 feet above O.D., are capped by a very sandy gravel in which about 

 half the stones are chert, and the hills near Ascot are capped with 

 a similar gravel. The writer saw no section at the Soldiers' Pillar 

 (Bowledge Hill), 309 feet above O.D., as it is enclosed, and Groat- 

 hurst Hill (Goater's HiU), 320 feet above O.D., is overgrown ; but 

 I have seen a good section on Chavey Down at 302 feet above O.D., 

 and I believe the gravel on all the Ascot hills is of much the 

 same character. The section showed 3 feet of mottled red and 

 white gravel and sand in irregular patches, very clayey in one 

 place. The gravel consisted of subangular flints and flint-pebbles 

 in about equal quantity, with a good deal of chert and several 

 sarsen-stones, the largest of which was 3x2| feet. There was 

 also a great number of small pebbles and fragments of quartz 

 up to -^ inch in longest diameter. Another pit, 1166 yards to the 

 east at Burleigh, close to the Schools, mapped as valley -gravel, 

 showed a section in very sandy gravel with abundance of chert, 

 well stratified with much current-bedding. This was at rather a 

 lower level. 



The gravel on these hills certainly resembles the sandy and cherty 

 gravel of Windlesham more than the gravel of the Chobham Eidges 

 plateau, and the altitude is nearly 100 feet lower. Prof. Prestwich 

 notes the difl'erence in composition,^ but his diagrammatic section 

 seems to imply that the two gravels are of the same age ; I, how- 

 ever, look upon the Chavey Down gravel as the more recent. 

 Farther west Wick Hill, near Bracknell, 276 feet above O.D., 

 Coppid Beech Lane, 270 to 302 feet above O.D., and Bearwood, 274 

 feet above O.D., are all capped by this gravel with abundance of 

 chert. A sample of small stuff" from the pit at 300 feet above O.D., 

 Coppid Beech Lane, gave the following result : — 



Subangular flints 25% of weight. 



Flint-pebbles 24 



Chert-fiagiiients 34 „ 



Quartz, small 15 „ 



Bagshot irony concretions 1^ „ 



1 See Quart. Journ. Geol. See. vol. xlvi. (1890) p. 100, and pi. vii. fig. 2. 



