108 



DESCRIPTION OF THE STRATA. 



slight trace of magnesia. It ought to be observed, that this speci- 

 men and No. 2 of the Sneaton limestone, and perhaps we may add 

 No. 4, may be considered as choice specimens, superior to most of 

 the blue limestone of our district. 



For the sake of comparison, it may be proper here to introduce 

 a table of the analysis of the magnesian limestone of the county of 

 Durham, taken from the account of that limestone, communicated to 

 the Geological Society by N. J. Winch, Esq.* 



By the Rev. J. Holme. 

 From Denton. 



Carbonate of Lime 63. 



of Magnesia 34. 



Alumina, Red Oxide of Iron, 1 q.<3\ 



and Bitumen j ...... .- 



Water 25 



100. 



By Sir H. Davy. 

 From Eldon. From Aycliff. 



33. 



45.2 



Iron 1.1 



Residuum ... 1.7 



100. 



.48.9 

 .46.6 



. 1.66 



,. 2.84 



100. 



From the hardness of our limestone beds, they furnish excellent 

 metal for repairing the high-ways; for which purpose the stone is 

 quarried in some places, as at Gnipe-houe, and especially at Coxwold. 



In closing our account of these strata, we may observe, that as 

 the coarse grey limestone is often schistose, so there is reason to 

 think, that it sometimes passes into shale. It has been remarked, 

 that in some places, as in Scugdale, there is a shale bed immediately 

 over the limestone ; and perhaps it will be found, that, in such cases, 

 as there, little or nothing of the grey limestone exists, its place being 

 occupied by the coarse sandy and calcareous schist into which it has 

 apparently passed. 



* Geological Transactions, IV. p. 7. 



