6o 



ally with its retreat horizontally. Some of these extinct 

 streams may be mentioned as having, with great pro- 

 bability, passed through the Greensand at its present 

 escarpment, as the Darenth at Plaxtol, and the Wandle 

 at Red Hill, but at a higher level than the present stream- 

 ways, of course. 



It will be seen that the crest of the greensand is 

 pierced at Redhill, Godstone, Oxted, Plaxtol, and Nettle- 

 stead. In the case of the Medway the Gap at Nettlestead 

 is on the N. and S. fracture, whose presence assisted the 

 river in breaching the chalk, but the river does not at 

 once run South, the obstinacy of the intervening mass of 

 Greensand obliging the stream to take a curved course by 

 Maidstone, some miles to the Eastward of the direct line ; 

 while from the Forest ridge the Teise runs to Nettlestead 

 in the right line of the fracture. It is probable that the 

 size and structural peculiarities of the area drained by the 

 Medway have given it great advantages over neighbouring 

 rivers. 



In the case of the Darenth, at the chalk escarpment 

 there is a transverse synclinal depression, opposite the 

 breach in the chalk the lower greensand is not breached, 

 and there is no synclinal depression, only a small flexure 

 of a local character running E. and W. But a breach 

 exists at Plaxtol, and I think that this breach was originally 

 made by the Darenth. It will be obvious to anyone 

 looking at a map, that there exists, though under altered 

 conditions and at a lower level than formerly, a line of 

 joint or weakness, which determines the 'direction of a 

 stream from Crowborough Warren by Withyham to Pens- 

 hurst, and a part of the Eden, in the opposite direction ; 

 this line if produced further South would join with that ot 

 the line of drainage of the Darenth through the chalk. 

 Somewhere in this line I think it likely that the 

 Darenth formerly commenced its course Northward, but 

 obstacles interfering with its more direct course, the river 

 ultimately found a way to breach the greensand further 



