Mr. Webster on the Purbeck and Portland Beds. 



39 



Nos 

 18. 



19. 



20. 



21. 



22. 



23. 



24. 



25. 

 26. 

 27. 



28. 



29. 

 30. 

 31. 

 32. 



33. 

 34. 



Thickness. 

 Ft. In. 



Backing 13 



Shiver, &c 3 



Royal 10 



Shiver, &c 3 



Devil's bed 6 



Shiver, &c 2 



Iron bed 4 



Shiver, &c 2 



Red rag 10 



Shiver, &c ..20 



Upper rag 3 



Shiver, &c 2 



6 

 

 4 

 

 

 6 



Grub 8 



Shiver, &c 3 



Roach in 4 beds, good • ~j a, 2 



Grey bed, good . . . ( »£ 1 

 Thornback, good ... J 1 > 10 

 Freestone, good . . . J f=H 3 



Shiver, &c 2 



Lias, not worked 10 



Lias rag . 



Under rag 1 



Shiver, &c . 2 



Lead bed 



Shid bed ; . . 2 



Shingle, 2 beds I 



Shiver, &c 



Nos. 

 35. 



36. 

 37. 



38. 

 39. 



40. 



41. 



Thickness. 

 Ft. In. 



Downs Vein rag 



Shiver 3 



Grey bed, No. 2, not worked . 8 



Hone 10 



1 6 

 4 

 4 

 6 

 

 4 



42. 

 43. 

 44. 

 45. 



46. 



47. 

 48. 

 49. 

 50. 

 51. 



52. 



Hone not worked, marly 



Shiver 



Grey bed, not worked .... 



Upperbed-j Downs Vein. These 1 



Lower bed J divide into slates. i 



Shiver 



Cinder, useless. It is a bed of 

 oysters .... 



Stone, not worked 



Button ; splits into slates ... 



Feather, good 2 



Cap, used only in backing ... 1 



Flint, ditto 1 





12 



4 

 7 

 

 

 



Shiver 





1 



6 



Upper five-bed, sometimes " 









splits into 5 . . . . 



c 







6 



Under five-bed, ditto . . 



0) 







8 



White bed, good .... 



1 



8 



Tomb-stone, good . . . 



12; 







6 



Pudding, inferior . . . . _ 









9 



Sheer, used in backing .... 







8 



Shiver 







2 



f} 



Flint, used only in backing 









Although most of the stony beds are used for some purpose or other, yet 

 the quarrymen distinguish among them four principal groups, which they in 

 the language of workmen call veins. It is these beds only that are worked 

 for exportation, by means of galleries under-ground, which are carried on for 

 a considerable way, at the expense of the individual quarrymen who are the 

 proprietors*. 



The exact point of junction of the clay and sands which are the equivalents 

 of the Hastings beds, with the Purbeck limestone beds, cannot be seen in Swan- 

 wich Bay, as at this place there is a hollow that is level with the sea; but it may 

 be studied in Warbarrow Bay, Lulworth Cove, and several places to the west. 

 The bed which appears to be uppermost in the series of the Purbeck Hmestone 

 is one containing a very large proportion of green earth, the calcareous matter 

 appearing to be derived entirely from the fragments of a bivalve, of from an 



* Specimens of all these may be seen in the collection of the Geological Society. 



