1867.] WOOD SOUTH-EAST OF ENGLAND. 413 



gravels occur on the Chalk aud other fonnations, it is only fi-om 

 Huviatile occupation of them, — the sea, the recession of which it is 

 that I trace, haTing at this time ceased to occupy any portion of the 

 Chalk country, and receded to the inlets represented by the bottom 

 of the Weald valley in the south, by the Oolitic portions of the great 

 valleys of denudation in western V\^iltshire, and by the Lower Lias 

 valleys of the eastern and western flanks of the Cotteswolds. It is 

 to the gradual reversal of the country, produced by the continuous 

 elevation which took place in the south and south-west (as the 

 denudation proceeded in those directions), and which on the east coast 

 brought part of the earliest emerged land, represented by the Glacial 

 beds, again to the sea-level, that the apparently close relationship in 

 position borne by the implement -gravels to these beds in Bedfordshire 

 and west Suffolk is, as I contend, due. It is only necessary to ob- 

 serve, on the small-scale map of the memoir, the manner in which 

 the Ouse valley between Buckingham and the entry of the river 

 upon the Fen-country has been denuded thi^ough the Glacial beds, 

 and in which it opens out at either extremity to the early Post- 

 glacial sea, to perceive that the denudation of this valley is quite 

 independent of the river which occupies it — although in places, as 

 at Bedford, a small amount of denudation has been effected by 

 the river when, during the implement-gravel accumulation, it stood 

 at a higher level relatively to the country than it now does, and 

 when changes of level, insignificant in comparison with those I 

 have been tracing, took place. It will, I think, be found that the 

 sequence of the gTavels, as interpreted by their position relatively 

 to the progress of the denudation, in the manner shown in the 

 memoir, is quite in accordance with the evidence afforded by 

 their organic remains, as far as this has yet been made known, and 

 especially with the disaj^pearance from this country of certain forms 

 of mollusca, such as the Corhicula fluviatilis ; and, from the late 

 communication of iMr. Dawkins to the Society, this sequence appears 

 to be equally in accordance with the evidence afforded by the mam- 

 malian remains ; for, although I am compelled to dissent from the 

 geological views of that gentleman inasmuch as he supposes the beds 

 of the Thames valley to be synchi'onous with, or even older than the 

 Upper Glacial clay), yet his analysis of the mammaKan remains 

 afforded by these beds, when compared with those yielded by the 

 implement-gravels, affords evidence of an older facies. Being un- 

 aware of that fact until long after I had been led to an opinion of the 

 newer age of the implement-gravels by the study of the denudation, 

 I welcome this concurrence of testimony more than if, by being pre- 

 viously aware of it, I had been influenced by it in seeking the ex- 

 planation of the Postglacial structure. 



The extensive reversal of the drainage throughout the area is one 

 of the principal features which the progress of the denudation exhi- 

 bits ; and the fact that this is traceable in the valleys of rivers that 

 are affluents of the Thames, and in the western valley of the Ouse, 

 becomes important on account of the special features exhibited by 

 the former at its eastern extremity, to which I am about to allude. 



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