24 Geology. 



that the Paloeolithic implement found in Wickham Road, Brockley, 

 by Mr. A. Lewis, in 1874, came from a continuation of this 

 terrace (23). 



The deposits of an old stream which formerly flowed from 

 Shooter's Hill, by Morden College, Blackheath, and Belmont Hill, 

 and joined the Quaggy close to its junction with the Ravensbourne, 

 were recently exposed on the Belmont Hill Estate (24). They ex- 

 hibited contorted and other structures due to slipping and to the 

 solution of the Chalk which lies below. 



There is a good section in the old Ravensbourne gravels at West 

 Wickham, near Hayes Station, which has recently yielded many 

 bones of Pleistocene mammalia to Mr. W. H. Griffin and others, as 

 reported by him to the last Congress (25). 



Many palceoliths also occur at West Wickham, and have been 

 described by Mr. G. Clinch (26) and others. 



6. ALLUVIUM. BY W. W. 



Of the deposit of the rivers there is little to say. It consists of 

 silt or mud, which has solidified into marsh- clay ; but in the case 

 of the Thames this is notably varied by the intercalation of layers 

 of peat, made up of vegetable matter which has, to a large extent, 

 grown on the spot. Rootlets occur, and also trunks of trees ; and 

 it is clear that these trees cannot have grown under water (they are 

 now beneath the level of high tide), but must have flourished when 

 the land was at a slightly higher level than now. This is the latest 

 that we have of evidence of change in the level of the land. 



Fine sections of the peat and its associated deposits were seen 

 at Crossness Sewage Works, and along the line of the great sewer 

 across the marshes to that place. 



(23) Proc. GeoL Assoc., Vol. XVIII., p. 161. 



(24) Proc. Geol. Assoc., Vol. XVIII., p. 103. 



(25) S.E. Naturalist, 1906, and Kentish Mercury, Dec. 1st, 1905. 



(26) Quart. Jonrn. GeoL Soc., Vol. LVI., p. 8. 



