GEOLOGY 



elsewhere. As might be expected the deposits are of an estuarinc char- 

 acter where they border the Thames, the wide mouths of the Crouch, 

 Blackwater and Colne, and the inlets between Walton-on-the-Naze and 

 Harwich. Scrobicularia plana and Tellina balthica occur in the tidal 

 clays. 1 



Along the left bank of the Lea there is a variable breadth of Allu- 

 vium forming a succession of marshes. At Walthamstow during excav- 

 ations for the filter-beds and reservoirs of the East London Waterworks 

 Company in 186869, man y interesting remains were found and described 

 by Dr. Henry Woodward. Besides numerous land and freshwater shells 

 of existing species, many bones of mammalia and a few of birds and 

 fishes were obtained. There were skulls and portions of skeletons of 

 man, of prehistoric and later age, as well as implements of stone, bone, 

 bronze and iron. There were remains of dog, fox, horse, wild boar, red 

 deer, reindeer, roebuck, elk, urus and short-horned ox, also remains of 

 beaver in considerable abundance. As remarked by Dr. Woodward, the 

 work and enjoyment of the beaver is to construct dams, forming large 

 deep and clear pools of water, with a series of small waterfalls at in- 

 tervals. 8 



From Felstead, Chignal St. James, Roxwell and other localities in 

 Essex many land and freshwater mollusca have been obtained from shell- 

 marl and other alluvial deposits. 8 



Along the borders of the Thames valley many interesting sections 

 have been recorded. Thus an excavation made in 1890 for a new gas- 

 holder at Beckton, North Woolwich, showed the following strata : 



ft. in. 



{Soil i 6 

 Clay 26 

 Mud 14 o 

 Peat 20 

 Mud 10 



Valley Gravel. Ballast (gravel and sand) 200 



Basement-bed of London Clay and Woolwich and Reading Beds. 



The peat yielded much wood, including bog-oak, while in the 

 Alluvium down to a depth of twenty feet there were found human 

 remains and bones of ox [Bos taurus, var. prim/genius and var. longifrons\ t 

 red deer, wild boar, dolphin and whale. 4 



In other localities remains of birch, alder, hazel and yew have been 

 recognized. 



From the mouth of the Lea eastwards there is indeed a succession of 



1 See F. C. J. Spurrell, On the Estuary of the Thames and itt Alluvium,' Prac. Ceo/. Attec., roL 

 xi. p. 210 ; H. Robinson, Prac. Init. C. ., vol. xv. p. 196. 



1 Geol. Mag., 1869, p. 385 ; and 'The Ancient Fauna of Essex,' Trout. Eistx FitU Club, vol. 

 iii. p. 1. See also Holmes, Enex Nat., vol. xii. p. I. 



M. Christy, Enex Nat., vol. iii. p. I ; J. French, ibid. p. 1 1 ; A. S. Kennard and B. B. Wood- 

 ward, ibid. vol. x. p. 87. For other fossils from alluvial deposits, see Whitaker, Geologj of Undo*, vol. 

 i. p. 476. 



* The section was examined by Mr. T. V. Holmes and the writer, and the bone* were identified 

 by Mr. E. T. Newton. 



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