Geology. 1 1 



beds the greater part of the remainder. Rising nearly 200 feet 

 above the Thames Alluvium, the Blackheath Beds form the pebbly 

 plateau on which Bostal Heath, Plumstead Common, Woolwich 

 Common, Blackheath, and Greenwich Park stretch for seven miles 

 as an almost continuous belt of heath and common-land. The 

 edge of this plateau is crenated by valleys in every stage of for- 

 mation : some are mere hollows in the Blackheath Beds ; others 

 cut down into the Woolwich loams (e ; g The Slade) ; a more 

 advanced stage is exemplified in the East Wickham Valley, where 

 the stream has eroded its bed through the Tertiaries into the Chalk. 



South of the pebble-plateau lie several large areas of London 

 Clay, which at Shooter's Hill rises to 400 feet above O.D. From 

 Chiselhurst and Bromley the Tertiaries rise gently southward until 

 they are cut off by erosion at the outcrop of the Chalk. 



General Sections. 



The Woolwich district is fortunate in containing within its area 

 some of the finest sections of the London Tertiaries that can be 

 found within the whole London Basin. The great pits at Charlton 

 stiil show the complete succession from the Chalk to the Black- 

 heath Beds, and by the continued removal of vast quantities of 

 sand the detailed structure of the beds is laid bare in fresh sections. 

 The well-known section at Loam-pit Hill, Lewisham, is now 

 obscured by rubbish, but the Erith pits remain good, and in recent 

 years some excellent and very extensive sections in the little valley 

 below East Wickham have clearly shown the whole series from the 

 Chalk upward. 



Full descriptions of the sections at Charlton, Lewisham, Erith, 

 St. Mary Cray, with lists of fossils and a valuable digest of the 

 literature relating to the London Tertiaries, will be found in the 

 Memoir issued by the Geological Survey (7), which is a mine of 

 information on all matters relating to these beds. Mr Whitaker's 

 "' Guide to the Geology of London " will be found very useful as 

 an introduction to the larger volumes 



In the East Wickham Valley, Woolwich loams and Pleistocene 

 Drifts are largely excavated for brick-making. In the very exten- 

 sive sections now open the whole of the local Tertiary series may be 

 examined. As the section shows several features of interest, it is 

 here given in detail for comparison with the published descriptions 

 of Charlton, Erith, etc. 



(7) The Geology of London and of Part of the Thames Valley, 2 vols. 1889. 



