4 EXPLANATION OF THE PLATES. 



4. The pits at Loam Pit hill, described at page 285 of this paper : a section 

 of these pits is represented in this Plate, No. 2. 



5. Pits of sand and chalk on Blackheath hill. 



6. The cavern beneath the point at Blackheath. This is an extensive adit 

 driven into the substratum of chalk. 



7. Sand pits in the middle of Blackheath ; these are situated in the upper sands 

 of the plastic clay formation. In the year 1803, an extensive excavation 

 which had formerly" been made into these strata was laid open ; it was sup- 

 posed to extend to the chalk beneath, but the roof fell in and the passage 

 became choaked up before it had been explored. 



8. On the south-east of Montpelier Row, Blackheath, a pit was opened in the 

 plastic clay, by Mr. St. Leger, in 1805, and manufactured into various 

 articles of pottery. The shelly beds occurred in this pit. 



9. Slope of the hill on the north of Vanburgh fields, east of Greenwich. Here 



the shelly beds of the plastic clay are visible. 



10. A chalk pit at the foot of Charlton hill. 



11. Extensive sand pits near Charlton Church. This is the inferior sand of the 

 plastic clay ; the shelly beds are seen covering it. The section precisely 

 agrees with that of the great Woolwich pits. 



12. A chalk pit at the foot of the hill. 



13. The great sand pits of Woolwicli. The section they present is described 

 page 284, and represented in this plate, No. 3. About a hundred yards on 

 the east, the excavation is continued into the substratum of chalk. 



14. Here an abrupt declivity beneath the Marine barracks at Woolwich presents 

 a good natural section of the shelly beds of the plastic clay. 



15. The gravel pit at Plumsted, mentioned iu Mr. Parkinson's paper on the 



Vicinity of London. Geol. Trans, vol. i. 



16. A deep shaft sunk into the substratum of chalk; mentioned at page 290 of 

 this paper. 



17. A pit in the London clay with Septaria; near the rise of Shooter's Hill; 



see page 290. 



18. Chalk pits in the bottom of the ravine between Plumsted and Wickhara. 



19. Well on Boston heath, mentioned page 291 of this paper. 



20. Bridgend place \ Localities where the shelly beds of the plastic clay have 



21. Near Bexley / been dug into. 



22. A deep shaft sunk into the substratum of chalk and there communicating 



with horizontal adits. There are many sudi in the woods about Crayford 

 and Dartford heath. 



23. Green Street Green -^ In these localities the characteristic shells of the 



24. Cockleshell bank 1 plastic clay formation are abundantly found ; they 



25. Betshara. C are particularly described in Thorpe's Cot^tumale 



J Roffense and Hasted's History of Kent. 



26. Near Bromle^i . Here the ihell? of the plastic clay occur. 



