67 



beds over which it spreads, which shews that its course has 

 been always outward from the Weald. The Hoo gravels 

 appear to belong to the united beds of the Thames and 

 Medway, and in neither river is there a probability that 

 their course was the reverse of the present. (P/. n.Jig. 8). 



The true river -worn gravels which are found in the 

 upper part of the (extinct Wandle) Smitham Bottom do 

 not so far as I can discover contain any Wealden Sand- 

 stone, but Chert and Ironstone from the Lower greensand ; 

 and it is probable, therefore, that these gravels were laid 

 at a time when its tributaries had retreated within the 

 greensand escarpment ; but that must have still left the 

 stream a fairly good one, for from the level of the 400 feet 

 we can trace its old gravels lying under Foxley Wood on 

 the right bank at 350 feet or more, and near Caterham 

 Junction station a few feet lower, where a slip of the chalk hill 

 has slid over the bed of the stream and preserved a patch 

 of gravel beneath some 50 feet of chalk. The highest 

 gravels of this river have suffered much denudation to the 

 Southward, but they may be discovered capping the 

 tertiary hills of Norwood, and at an elevation exceeding 

 300 feet. It is, I believe to a thick deposit of the gravel of 

 the old river along the hills which stretch from Norwood 

 towards Deptford that we are to ascribe the existence of 

 those hills, which even where denudation has lowered them 

 remain to show the course of the old river. The broad 

 spreads of gravel about Croydon still attest the importance 

 of the former stream by the large quantities of material 

 which have been swept from its abandoned course to cover 

 the gathering ground of the modern Wandle. 



I would suggest that the old Wandle gravels of this 

 high level at Norwood may approach the same date as 

 those on Strood Hill already mentioned. In neither case 

 are there any foreign or erratic pebbles mixed with them. 



Along the Northern brow of the Thames Valley, near 

 the district I am examining, is a layer of gravel. It is 

 evidently Marine, and is frequently called by Mr. S. V. 



