206 THE RIVER VALLEYS OF 



regarded as purely fluviatile. The coarse and fine 

 deposits in the drift of the Weald valley would appear 

 to be estuary accumulations, as similar series are found 

 in all estuaries in one place nothing but clays and 

 the like, and in others gravel or shingle ; while rivers 

 must form alternations of fine or coarse accumula- 

 tions, according to the height of the waters. 



Proofs are not wanting of the valley of the Weald 

 having oscillated up and down during the most re- 

 cent ages. According to Mr Drew, 1 a bare pole was 

 put down 70 feet in Romney Marsh without reach- 

 ing the bottom of the recent accumulations, the 

 lowest 50 feet of which were sand containing " recent 

 marine shells, especially cockles." Over this sand there 

 are in places five or six feet of peat, containing the 

 roots, stems, and fruit of trees, such as the oak, alder, 

 hazel, &c., and over the latter a clayey, peaty, or 

 sandy alluvium. Clay also sometimes occurs over- 

 lying the peat, while "the whole of the alluvium is 

 below the level of high water at spring- tides." 



According to Dr Mantell, 2 " in Pevensey Level 

 the trunks of large trees have often been observed 

 imbedded in a mass of decayed vegetables. The sub- 

 stratum is an inferior peat, with an intermixture of 

 sand reposing upon a thick bed of blue alluvial clay, 

 containing marine shells ; " while at Irfield, " nearly 



1 "Memoirs of the Geological Survey, England," Sheet 4. 



2 MantelTs " South-east of England." 



