﻿Yol. 66.~] THE WESTEKN END OF THE WEALD. 681 



Beginning with the last-named river, we find that it rises at the 

 foot of the Alton Hills, near Selborne, flows southwards as far as 

 Petersfield, and then, turning to the east, pursues the remainder of 

 its course along the foot of the South Downs. Some remarks on its 

 extension to the north of Petersfield will be found in my former 

 paper (2, p. 329), and only the part which lies between that town 

 and Pulborough need be considered here. Although the strata in 

 this region are thrown into numerous folds, the river seems only 

 in places to coincide with the latter, and offers no reason for 

 doubting that it is a true subsequent river, in the formation of 

 which numerous consequent streams must have been captured. 

 Unfortunately, though the summit of the Downs is furrowed by 

 several passes, there is an entire lack of Drift, so that we cannot, 

 as in the case of the North Downs, prove by the presence of chert 

 the former connection of these passes with streams which once 

 drained the Lower Greensand area. The Cocking gap, which sinks 

 as low as 340 feet O.D., may plausibly be conjectured to have had 

 such a connection, and there are several other passes well below the 

 500-foot coutour ; but it is not safe to assume in such cases that 

 their present height at all closely represents the level at which 

 their streams were beheaded, or even that they necessarily had a 

 Wealden connection. For example, there is a very low pass between 

 Petersfield and the Meon Valley ; but the gravels of the latter 

 contain no chert, and to suppose that any Wealden river ever flowed 

 out in this direction would add greatly to the difficulty of accounting 

 for the northern branch of the Kother, which stretches, past Liss 

 and Greatham, far to the north of the original watershed. 



From calculations based on Section 73 of the Geological Survey, 

 I estimate that the Chalk originally extended over the plain as far 

 as Henley Hill, some 5 miles to the north of the existing Downs ; 

 but there is evidence that the subsequent river, instead of waiting, 

 as the Tilf ord Biver did, until most of this Chalk had disappeared, was 

 formed in the Lower Greensand at an early period considerably to 

 the north of its present position. As long ago as 1851 Murchison 

 (16) described extensive sheets of gravel, containing an abundance of 

 subangular flints, in this south-western corner of the Weald. More 

 recently Dr. Elsden (4) has again called attention to them, and, 

 associating them with others farther east, he comes to the conclu- 

 sion that they are unconnected with existing rivers, and point to an 

 ancient plateau between the Chalk and the central dome. So far 

 as I have been able to examine one of the largest and highest of 

 these sheets of gravel — namely, that on Rogate Common (about 

 500 feet CD.) — it bears a general resemblance, in the subangular 

 character of its flints, to some of the gravels of the Alice Holt 

 plateau, near Farnham ; and its distance from the Western Downs 

 (Wheatham Hill, etc.) is very much the same as that of these latter 

 drifts from the Chalk round Alton. It appears to me highly 

 improbable that so wide an extent of flint gravel could have been 

 deposited in its present position by consequent rivers ; but I see no 

 difficulty in believing that it was brought from the west by an early 



