Wealden District and the Bas Boulonnais. ]3 



Brenchley ifii/.-— This hill is situated about five miles nearly east of Bidborough 

 Hill, to which it is exactly similar, except that it affords more distinct evidence of 

 its being strictly an anticlinal ridge. East of the castle I found opposite dips of 

 nearly 20° to the east of north and about J 6° to the south, and so near to each 

 other as to determine accurately the position of the anticlinal Hne. It there lies a 

 little south of the summit of the ridge. 



Brenchley and Bidborough Line. — Bidborough and Brenchley Hills are connected 

 by a range which overlooks, the valley occupied by the Weald clay, and is formed 

 by the comparatively rapid rise of the beds of the Hastings sand from beneath the 

 clay. It diminishes in height (probably by denudation) as it approaches the eastern 

 extremity of Bidborough Hill, from which it is separated by an ill-defined trans- 

 verse valley. A distinct line of flexure thus connects the two hills above mentioned, 

 though the evidence may be somewhat less forcible than it is in those two striking 

 localities. The line of curvature is continued in an exactly similar manner to the 

 west of Bidborough, but becomes less distinct as we proceed westward, and loses 

 all determinate character north of East Grinsted, It dies away also in the same 

 manner at the other extremity east of Brenchley Hill. 



Transverse Valleys and Fractures of the Central Ridge. — It will be observed that 

 the continuity of the range just described is broken in three places, at Penshurst 

 by the valley of the Medway, between Bidborough and Brenchley, and again east 

 of Brenchley Hill by the valley before mentioned, along which a small stream 

 rising at the foot of Frant Hill and passing by Lamberhurst finds its way to the 

 Medway. The first is the most remarkable of these transverse valleys. 



I have already spoken of the watershed formed by the transverse high land which 

 passes by Rotherfield and Frant ; and if we proceed northward from the latter place 

 along the Tunbridge road, we find (as shown by the map) that the streams which 

 rise along that line on the right run to the east, and those on the left run westward, 

 so that the watershed is continued northward as far as the valley of the Weald 

 clay, notwithstanding the great alteration in the external surface produced by de- 

 nudation to the north of Frant Hill. The Medway is formed by the confluence, 

 about Ashurst, of the streams which thus flow westward, with others running 

 principally from west to east along longitudinal valleys. From this point it takes 

 its course by Penshurst directly through the longitudinal range above described. 

 If this transverse break in the range were now filled up, a lake of considerable 

 area would be formed in the valley of the Medway, with branches ramifying along 

 the diftierent valleys which communicate with it. Supposing such a barrier to have 

 once existed, in this and similar cases which may hereafter be considered, the point 

 to which I would immediately direct attention is the evidence which may enable 

 us to judge how far the destruction of the barrier may have been facilitated by the 

 previous existence of a transverse fracture. 



