398 Wood— On the East Essex Gravels. 



creased by coast-action during emergence, may assume forms iden- 

 tical with most of the valleys and gorges which diversify the surface 

 of the land. (See some excellent observations on the marine origin 

 of valleys in Lyell's Elements.y 



TTT . — On the Relatiok which the East Essex Gravel, bears 

 TO THE Structure of the Weald Valley.. 



By Searles V. 'Wood, Jun., F.G.S. 



[Continued from the August Number, p. 354, -which contains the Map and Sections 



referred to.] 



IN the former paper^ T adverted to the evidence which the Thames 

 gravel afforded, that the channel in which it was deposited 

 opened out over the Wealden area, and the corroborative evidence 

 which the East Essex gravel furnished of a similar state of things. 



The Map accompanying this paper (see the August number) 

 shows the East Essex gravel running down from the NN.E., across 

 the months of the Thames and Grouch, its course becoming as it nears 

 the Weald parallel with the eastern edge of the Thames gravel. 

 In consequence of the extent of marsh on the eastern side of the 

 Medway, between Chatham and Sheerness, the extension of the 

 gravel in this dii-ection does not appear; but the southern termi- 

 nation of the great sheet at Hoo, near Eochester, is an abrupt one, 

 extending along a line parallel with the Chalk escarpment of the 

 Weald at that part. 



In the Thames Valley paper, I showed (see Section 7 of that 

 paper, p. 103 of Vol. III. cf this Magazine) that the Thames gravel 

 was cut down by a sharp denudation in tJie opposite direction to the 

 river Thames, and in the direction of the Weald, and that a newer 

 gravel {x5) extending to the Chalk country, forming the north side 

 of the Weald Valley, had been formed under the brow of the Thames 

 gravel. Now the features exhibited by the. East Essex gravel are 

 similar in this respect; for the great sheet which thus terminates 

 parallel with the contiguous chalk escarpment, is cut down in the 

 most decided and abrupt manner towards that escarpment. 



Owing to the dip imparted by the ujpheaval of the Weald country 

 to this gravel near Eochester, it descends eastwards by a rapid 

 slope to the Medway, and northwards more gradually towards the 

 Nore ; but a line drawn from the veiy high ground occupied by this 

 gravel on Hoo Common, to the nearest scarp of the North Down, 

 shows this cutting down very distinctly. (See Sec. 14 beside Map.) 



In this Section the gravel (x4//) is divided from the Chalk by a 

 considerable thickness of London clay and Lower Tertiary sand, and 

 the whole have been cut down together to the Chalk at Eochester, 

 and a newer post-glacial bed {x5^) has been formed at their foot. 



^ Answers to other parts of Mr. Maw's article will he found forestalled in the 

 preceding pages. 



2 Geological Magazine, Vol. III., pp. 57 and 99. 



