292 The Rev. W. Buckland on the Plastic Clay Formation. 



In the banks of the Croydon canal at New Cross near De'ptford is 

 another section that confirms the place that has been assigned to the 

 Woolwich beds below the London clay, and connected with the 

 plastic. The section does not penetrate so deep as the thick ash 

 coloured sand of Woolwich ; but in the canal bank above the bridge 

 we have the following beds laid open, though not sufficiently to 

 ascertain their exact thickness, it does not however vary much from 

 that of the upper beds in the Woolwich pits. 



Section at the Canal in New Cross, beginning from the lowest bed. 



No. 



1. Plastic clay abundantly charged with the same shells as in the 



Woolwich pits. 



2. Bed of small pebbles chiefly of rolled chalk flints. 



3. Sandy loam and plastic clay. 



4. Blue clay full of small selenites, probably the London clay. 



The blue clay, No. 4, probably owes its selenites to the decom- 

 position of its shells and iron pyrites ; at present no shells are visible 

 near the surface. Its juxta position to the London clay of the 

 Sydenham Hills, of which it seems to be the continuation at their 

 north-east extremity, goes far to identify it with that formation. The 

 plastic clay, No. 3, is used for bricks and coarse pottery in a field 

 adjoining this canal called Counter Hill, close to the New Cross on 

 the east ; and the Woolwich shell beds may be seen again at a lock 

 of the canal'about a mile above New Cross towards Croydon, in the 

 plain that lies under the east side of the Sydenham Hills. At this 

 lock Mr. Warburton pointed out to me the following shells. Ancilla 

 buccinoides, cerithium denticulatum, cyclas deperdita, a small bucci- 

 num, and a small nerite. 



