﻿322 ME. H. BimT ON THE EIVER WEY. [^aV I908, 



joining this consequent river from the east ; certainly the bulk of 

 the Godalming Eiver must be regarded as a subsequent outgrowth 

 from the Guildford Wey. The next stage of evolution seems to 

 have been the capture of the consequent river and the Tilford 

 stream by the Godalming Eiver at, or near, Tilford. I can find no 

 direct evidence of this, and nothing to show how much the level of 

 the river at Tilford was lowered by this capture ; but it is perhaps 

 significant that, while flints are found in fair numbers in the 

 gravels on both sides of the "fiKord Eiver, they are almost entirely 

 absent in the Godalming Valley, except at a very slight elevation 

 above the present river-bed. 



The Waverley Yalley would at this stage be left practically dry, 

 but the Farnham and Scale Elvers would still continue to join the 

 Black water. Previous to this the whole gap in the Chalk between 

 Hungry Hill and the Hog's Back formed one wide valley, but now 

 the mass of water was so far diminished that the Scale and 

 Earnham E-ivers got separated, and proceeded to carve out each its 

 separate valley, leaving the existing Chalk mound between them. 

 If this be a correct interpretation of the facts, this mound may be 

 taken (with due allowance for recent denudation) as a measure of 

 the level of the river-bed at the time when the consequent river 

 was diverted ; and we shall see other reasons later on ^ for thinking 

 that this is the case. We may farther infer that the erosion of 

 the Blackwater Yalley since that time has been extremely slow, 

 for the tiny Scale stream has been able to carve out a comparatively 

 wide valley. 



■ The final change by which the present river-system was estab- 

 lished was doubtless the outgrowth of an obsequent stream from 

 Tilford, along the line of the old consequent valley (Waverley 

 Yalley) until it met the Farnham Eiver; then the latter turned 

 aside from the Blackwater, and rapidly lowered its bed some 50 feet 

 to accommodate itself to the level of the Godalming Eiver. Herein 

 lies the interest of a gravel-capped terrace which runs along the 

 south side of the Farnham Yalley, from its junction with the 

 Waverley Yalley to a point some 3 miles farther west. It stands 

 about 50 feet above the present river-bed, and thus corresponds 

 closely in level with the watershed now dividing the Wey from the 

 Blackwater. It is, in fact, a remnant of the old river-bottom, and 

 affords a useful example of the formation of a terrace by river- 

 capture, without any help from local or general elevation ; while 

 the steepness of the bank below is an indication that the changes 

 which gave rise to it were both rapid and recent.^ 



The entrance to the Waverley Yalley presents a striking contrast 

 with the Farnham Yalley, out of which it leads, being much narrower 

 and steeper ; and indeed it exhibits just the features which we 

 might expect to result from the diversion of a longitudinal river into 

 a small obsequent valley. The latter does not follow exactly the 

 line of the old consequent valley, but has shifted more to the east. 

 This is shown, not only by the steepness of the left bank all the way 



1 § III, p. 326. 



^ Other proofs of this are to be found all the way up the valley. 



