Geology. 17 



A trench opened in May, 1905, at the corner of Well Hall Road 

 and Shooter's Hill Road showed : 



Brown London Clay, 3 feet. 

 Closely packed pebbles, 3 feet. 



The basement-bed of the London Clay appears to be unfossil- 

 iferous in this district. 



The thickness of the clay at Shooter's Hill is about 200 feet : 

 this is barely half the thickness shown in other parts of the London 

 Basin, but the presence of a Drift gravel on top of the hill shows 

 that the full thickness is not preserved. 



Sections in the London Clay lack the variety which adds so greatly 

 to the interest of the Lower London Tertiaries. There are many 

 exposures in brickfields and temporary excavations for sewers, 

 etc., but the best section now open is that on the northern shoulder 

 of Shooter's Hill. Here about 15 feet of stiff clay is shown with 

 large septarian nodules. In a trench in Eaglesfield Road, in 1902, 

 the septaria yielded a few specimens of MODIOLA and CORBULA. 

 No other fossils are recorded from Shooter's Hill. A few long 

 slender crystals of selenite were obtained in the same trench. 



5. DRIFT, ETC. BY A. E. S ALTER, D.Sc., F.G.S. 



The area dealt with consists of the lower parts of the Darenth and 

 Ravensbourne valleys and the country between them. Reference 

 is also made to the important Drift deposits found near Swans- 

 combe and Northfleet, which, although outside the area, are 

 intimately connected with it. 



High Level Drift. 



The highest and presumably oldest Drifts are found capping 

 the Tertiary deposits at Well Hill, near Chelsfield, 610 feet above 

 O.D. ; at Shooter's Hill, 424 feet above O.D. ; and at Swanscombe 

 Hill, 320 feet above O.D. 



At Well Hill, on the water-parting of the Cray and the Darenth, 

 is a thin gravel consisting principally of flint, but containing also 

 a fair number of Lower Greensand chert-fragments, and small 

 pebbles of rose-coloured, milky and transparent quartz, derived 

 from older strata in the Wealden area. Mr. Russell Larkby (n) 



(11) Antiquary, March and April, 1905. Proc. Geol. Assoc., Vol. XIX., 

 p. 235. 



C 



