JET. 37.] LOWER TERTIARY STRATA. 71 



in the other strata as they travel northward. On no part of the 

 north side of the London Tertiaries am I aware that fluviatile 

 beds have been found. At the period just before the London 

 Clay commenced shallow seas and lines of coast are indicated, 

 both by these river-deposits, and by the occurrence at several 

 places of rocks bored by the Pholas. These south-coast rivers 

 would certainly seem to have flowed over land now occupied by 

 the area of the Wealden, but whether the chalk then covered it 

 almost to the exclusion of the older beds or not it is difficult to 

 say. I am rather inclined to look to the chalk for the supply of 

 the greater part of the beds below the London Clay, but yet not 

 to this entirely. The London Clay is, I think, derived from 

 another quarter, and a more distant one. The first deposited 

 Tertiary bed was broken up, and its fragments scattered in some 

 of the beds but little younger; and, again, the London Clay, I 

 believe, swept over and denuded Tertiary beds older than itself, 

 for [to] this action only can I attribute the number of small black 

 flint pebbles thinly dispersed at places in the beds of the London 

 Clay. These pebbles, I believe, come from the shingle beds below 

 the London Clay, but whence they were originally derived it is 

 more difficult to say probably, I think, from upper denuded 

 beds of chalk. This is a point I am looking to at present. The 

 movement which upset the Tertiaries of the Isle of Wight I 

 think long anterior to the denudation of the Weald as it' now 

 exists; yet may it not be quite possible that the elevation of 

 the Weald existed before this period, and that the elevation and 

 denudation were independent of each other ? 



The amount of vertical subsidence in the Isle of Wight 

 between the Chalk and the first appearance of land above 

 the waters must, I think, have been nearly 2000 feet and 

 that an uninterrupted, tranquil, and noiseless action. (Never- 

 theless I believe in paroxysms.) The green-coated flints next 

 the Chalk I quite agree with you in attributing to a large and 

 extensive destruction of the Chalk. This was the commencing 

 scene of our English Tertiaries. The plants of Alum Bay 

 and Bournemouth imply no doubt the contiguity of dry land, 

 but still probably not a very near one, and an open sea, whilst 

 the fresh-water Eocenes [Oligocene] indicate a closing up of the 

 seas and the extension near at hand of fresh water. 



