VALLEY AND ITS KELATION TO THE WESTLETON BEDS, ETC. 17-') 



that the formation of this deposit was followed by an upheaval which 

 brought it to the surface, and gave rise to a low mountain-range on 

 the site of the present Wealden area. We are able to fix the time witn 

 tolerable accurac}^, by the absence of the later Crags in the upraised 

 district, and by the presence of debris derived from that district 

 in some of the deposits in the area which remained submerged. 



Thus at the base of the White Crag, subangular flints, flint- 

 pebbles, a few white quartz-pebbles, some light-coloured quartzite- * 

 and a few sandstone-pebbles, of which one contained the cast of an 

 Astarte (Oolitic ?), have been found, and with these one consider- 

 able-sized boulder of red felspar- porphyry. These afford but little 

 guide for the direction whence they drifted. There is an absence 

 of chert and ragstone, such as might be expected to be present if 

 the denudation of the Wealden anticlinal had commenced or been far 

 advanced. 



With the E-ed Crag, we have certain proof of denudation of the 

 Lower Greensand and of the earlier Pliocene bed, for in the Copro- 

 lite-bed at the base of the Eed Crag at Sutton there are found : — 



1. Large angular flints from the adjacent Chalk. 



2. Mint-pebbles from Tertiary or Diestian Beds. 



3. Light-coloured quartzite-pebbles. 



4. Pebbles of White or Coralline Crag. 



5. Pebbles of white quartz. 



6. Pebbles of iron-saudatone (Diestian ?). 



7. Pebbles of a light- coloured sandstone with impressions of Pecteu and 



Astarte (Oolitic ?). 



8. Subangular fragments of cJiert and, ragstone (Lower Greensand). 



And at the base of the Red Crag at Frimley, in addition to the 

 above : — 



1. Pebbles of fossiliferous ironstone and box-stones (Diestian?). 



2. Subangular fragment of a white felspathic sandstone. 



3. A small boulder of red granite with green and black hornblende. 



4. Subangular fragments of brown chert with sponge-spicules. 



It is evident, therefore, that the denudation of the Weald had 

 then commenced t, and that the Lower Greensand had been reached, 

 although the quantity of chert- and ragstone-debris had not yet 

 attained the proportions it acquired at a later period, when the 

 Greensand-strata had. become more worn down and exposed. 



If, then, this Wealden range already existed at the time of the 

 Eed Crag, it follows that its denudation which then commenced must 

 have been going on during the later times of the Chillesford Clay and 

 of the Porest Bed. It was at that time probably that the winter snow 

 and spring floods swept down the Lower-Greensand debris over the 

 Chalk-plateau and Tertiary hills to the north. It was a period in 

 all probability of great humidity and heavy rainfall, for there is some 

 evidence that at no great distance to the south of the aforesaid range 

 there were Pliocene seas with warm currents to furnish an abundant 

 evaporation. 



* In my earher papers I used the term siliceous sandstone instead of juarlzite. 

 t Quart. Journ. Geol. See. vol. xxvii. p. 353 (1872). 



