MS. 37.] DENUDATION OF THE WEALD. 69 



and of the existence of coast -lines, in the fluviatile beds of 

 Woolwich, Upnor, &c., in the banks of round flint pebbles of the 

 hills from Croydon to Kochester, and in the presence of rocks 

 bored by the Pholas in parts of Kent, Essex, and Middlesex. 

 Yet I should hesitate in placing the then dry land in the position 

 of the present Wealden, although it is probable that a large 

 eastern portion of this district may have been dry land. But 

 the system of hills and valleys is so uniform through the Wealden, 

 and, I think, so evidently the result of one system of forces, that 

 no partial or disconnected actions could possiby have produced 

 so harmonious a result. 



I fully admit the force of your observations respecting the 

 obliteration of the older denudation by others of more recent 

 occurrence, and that there is every probability that some portions 

 of the Cretaceous (and possibly the Wealden) rocks were above 

 the sea during the Eocene period; but, nevertheless, I cannot 

 help considering the entire present surface of the Wealden as 

 resulting from causes of comparatively recent date, subsequent 

 even to the period of the Great Northern Clay Drift. I cannot 

 separate the denudation of the Wealden from the denudation of 

 the valley of the Thames and all the surrounding districts, yet 

 there are some strong natural historical facts to militate against 

 this view, and my acquaintance with the district is not yet 

 sufficient to allow me to form a well-considered opinion. With 

 the country around London I am better acquainted, and hope in 

 the course of the next session to have the pleasure of submitting 

 to you some papers on this subject. I have had them in hand 

 some time, but have hesitated to bring them forward until my 

 observations were much more extended. In the Tertiary district 

 the Drift must, I think, be separated by four or five (may be even 

 more) well-marked divisions, part of them older than the Great 

 Northern Clay Drift, and independent of the present configura- 

 tion of the land, and part of them of date subsequent to the 

 denudation of the existing valleys. Thus I am rather inclined 

 to the opinion that the commencement of the Drift period cannot 

 be placed farther back than of Post-Pliocene age, and that the 

 denudation of the Wealden and the excavation of all the systems 

 of valleys of the south-east of England resulted from the opera- 

 tion of forces acting simultaneously throughout this area during 



