part 1] SECTION AT WOEMS HEATH. 19 



best sections have been seen, to a depth of 15 feet, and some small 

 quartz-pebbles have been found. 1 



The easternmost patches mapped are near North Boarhunt : five 

 to the west and north-west of the hamlet, on the Eooksbmy 

 outlier ; and two to the east, on the Walton -Heath outlier. 2 



At their outcrop, immediately north of all these occurrences of 

 Bagshot Pebble-Beds, the Lower London Tertiaries show no sign 

 of pebble-beds, with one exception on the west, where the possible 

 Blackheath Beds at Braishfield come within 2 miles of Ganger 

 Common. The next nearest occurrence of the older beds to the 

 newer is near Sherfield English, where the former crop out some 

 4 miles west of Ganger Common. 



On the other hand, in those parts of the Hampshire Basin where 

 possible Blackheath Beds occur (and it is no matter what we 

 call them) there are no marked pebble-beds in the neighbouring 

 Bagshots. 



Moreover, the newer set of beds is here bigger than the older. 

 So altogether one is led to conclude that the Bagshot Beds of the 

 Hampshire Basin got their pebbles direct from the Chalk ; for the 

 greater part, at all events. Of course, the sea that crossed over 

 any pre-existing pebble-beds, on its way over the London Clay and 

 the Lower London Tertiaries to the Chalk, would mop up any such 

 that came in its way. 



Of other and newer Tertiary pebble-beds there is not much to 

 say : it is rare for any to approach the Bagshot Pebble-Beds in 

 importance. So far as I know, the only part in which such newer 

 pebble-beds have been mapped is in Sheet 269, of which I have been 

 shown a MS. copy, and in the Memoir in which the}' have been 

 described. Some belong to the Bracklesham Beds and some to the 

 Barton Sand, and the latter are noticed under the heading ' Base- 

 ment Pebble-Bed.' The chief masses of these are south of Sunning- 

 dale, on Chobham Common, and at Stannershill, north-east of 

 Chobham, all in one neighbourhood, and the thickness goes up to 

 16 feet. Mr. H. Dewe}^ says of them that the flint-pebbles are 



' associated with a few pebbles of vein-quartz and Greensand chert. The 

 occurrence of chert at this horizon is noteworthy, for so far pebbles of this 

 material have not been found in any of the underlying Tertiary deposits.' 3 



Y. General Kemarks on the above-described Beds. 



The foregoing pages have dealt chiefly with sets of beds that 

 may be called insignificant, mere trifling incidents in the great 



1 See ' The Geology of the Country around Winchester, &c. ' Mem. Geol. 

 Surv. 1912, pp. 56. 57 ; and ' The Geology of the Country around Southampton ' 

 Mem. Geol. Surv. 1902, pp. 13, 14. 



2 See ' The Geology of the Country near Fareham, &c.' Mem. Geol. Surv. 

 1913, p. 55. 



a 'The Geology of the Country around Windsor ' Mem. Geol. Surv. 1915, 

 pp. 41, 43, 44, 52-55, etc. 



C2 



