Deposits containing Fossil Plants. 93 



The ' Submerged Forests ' met with during the excava- 

 tion of Tilbury Docks apparently belong to the same 

 period as those seen at Crossness and at the Albert Dock; 

 they underlie a layer with Roman remains, but the small 

 list of plants includes nothing characteristic of any par- 

 ticular date : — 



M 



Sambucus nigra. Quercus Robur sessiliflora. 



Betula alba. Sparganium ramosum. 



Alnus glutinosa. Carex. 



Corylus Avellana. Phragmites communis. 



Trimingham, Norfolk. 



(Reid, 'Geology of the Country around Cromer,' 1882 ; 

 and ' Pliocene Deposits of Britain,' Mem. Gcol. Survey. 

 1890.) 



Good sections of the Preglacial Cromer Forest-bed can 

 be seen at the foot of the cliffs and on the foreshore at 

 Trimingham. The Early Glacial freshwater deposits may 

 also be represented there ; but I have not yet been able to 

 find any of the characteristic Arctic plants in them. 



Twickenham, Middlesex. 



(Leeson & Laffan, ' On the Geology of the Pleistocene 

 Deposits in the Valley of the Thames at Twickenham. 

 . . . .' Quart. Journ. Geol. Soc., Vol. L., pp. 453-462. 

 1894.) 



A small silted-up channel is here found beneath the 

 Thames gravel. It is of interest as yielding mammals 

 which perhaps point to a transition between the Palaeo- 

 lithic and Neolithic periods. The species are the Bison, 

 Reindeer, Horse, and Bos longifrons. The plants include 

 Galeopsis Tetrahit, usually a weed of cultivation ; but there 

 are no definite signs of cultivated plants or domesticated 



