﻿Vol. 64.] ME. H. BTJRT ON THE EIVEE WEY. 327 



In conclusion, it is worthy of remark that the Alice-Holt plateau, 

 on which the drift must have accumulated under rather peculiar 

 conditions, stands quite alone in the western area of the Weald. 

 The only other extensive sheet of high-level gravel is on Hungry 

 Hill, 250 feet above this plateau ; but it belongs to a far earlier 

 period (Southern Drift), and contains no traces of Palaeolithic man. 

 If, as is possible, this Southern Drift marks the close of the first 

 cycle of erosion ^ (and it can scarcely be earlier), then more than 

 half the denudation of the second cycle had taken place before 

 the Palaeolithic gravels were deposited ; but, on the other hand, 

 all the adjustments which we have followed, from the capture of 

 the consequent river to the diversion of the Parnham Eiver, are of 

 decidedly later date than those implements. 



ly. The Alton District. (PI. XXXYII.) 



The Parnham branch of the Wey (Section YI) runs a very 

 straight course between Alton and its turning into the Waverley 

 Yalley — a distance of about 10 miles, — but passes over several 

 different strata. Eoughly speaking, the lowest third of its course 

 is in Lower Greensand ; the middle third in Gault ; and the upper 

 third in Upper Greensand and Chalk. But, although the main 

 valley is continued up to Alton, what is generally regarded as the 

 head of this branch of the river comes in from the south nearly 

 a mile below that town, not far from the village of Wilsham, and 

 is marked in the 6-inch Ordnance-Survey map as the Caker Stream 

 (see PI. XXXYII). Following it up towards its source we first pass 

 through a narrow gorge in the Chalk, and almost immediately find 

 ourselves in a broad and flat valley, which seems at first sight to 

 stretch all the way to Selbourne (8 miles) ; but the southern end of 

 it, though separated by no very well-marked watershed, drains into 

 the Oakhanger Stream (Section lY). On the east side of this 

 valley the Upper Greensand rises, with a gentle dip-slope, to about 

 500 feet above Ordnance-datum ; while on the west is a range of 

 Chalk hills, rising to about the same height, but interrupted by 

 frequent valleys, and presenting extensive surfaces of nearly-level 

 ground. The Caker Stream runs, for the most part, at the junction 

 of the two strata ; while the Chalk, however, contributes but little 

 to it, several streams join it from the Greensand slopes, and it is to 

 these that Topley alludes when he writes " : — 



' The streams which feed the Wey itself ' [that is, the Farnham branch] ' take 

 their rise often in the Upper Greensand itself, and flow over the Chalk to 

 the north and north-west. The drainage of this north-eastern ' [north- 

 western is meant] ' corner of the Weald is exceedingly cnrious and unlike that 

 of any other parts of the district.' 



But, before attempting an explanation of this very interesting fact, 

 we must first face the larger problem (not directly referred to by 

 Topley) of how so great an extent of Chalk ever came to drain into 

 the Wealden area. Elsewhere the only contributions of the Chalk 



1 See W. M. Davis, Geogr. Journ. vol, v (1895) p. 135. 



2 ' Geology of the Weald ' Mem. Geol. Surv. 1875, p. 196. 



