THE CORALLIAN ROCKS OF ENGLAND. 301 



The thinning of the lower beds in this direction is proved by 

 the Coral Rag coming back again to the same position with reference 

 to the general strike, as is seen in all the quarries on the road to 

 Faringdon. 



5. Faringdon to Oxford. 



We here enter upon the region studied by Whiteaves and 

 Phillips, and upon a distinct sheet of the Geological Survey ; but as 

 our object is to give somewhat more detail than they have done, we 

 still have something to do. 



Of the Corallian rocks in the neighbourhood of Faringdon we are 

 able to give a tolerably complete section, which will serve more 

 or less as a type and standard of comparison for the rest of this 

 district. We may first see the passage downwards of the Kim- 

 meridge Clay in a clay -pit a little to the south-east of the town, 

 where we have the following section : — 



Section in Faringdon Clay-pit. 



ft. in. 



1. Solid pale grey unstratified Kimmeridge Clay 6 



Gradual passage into a reddish-brown porous 



earth 9 



2. Chocolate-coloured ferruginous earth, with black 



stains from dissolved fossils, and lumps of cal- 

 careous clay, ironstone, and fragments of Ostrea 

 deltoidea and Serpula towards the base 1 2 



3. Coral Eag, with the surface and fissures iron-stained 3 4 



This shows us the fragment of ferruginous beds which here and 

 there appear to have escaped removal by denudation before the for- 

 mation of the Kimmeridge Clay, as we have seen near Preston and 

 in North Dorset, and spreading over the surface at Shrivenham. 

 They remind us, by the association of Serpula tricarinata with large 

 fragments of Lima pectiniformis, by the presence of numerous Pinnce, 

 and by the occurrence of a peculiar Ammonite (A. decipiens), of the 

 great development of this class of rock at Sandsfoot Castle. The 

 surface of the Rag, as usual when thus overlain, is uneven, with the 

 red earth in the interstices, showing a kind of unconformity. The 

 continuation downwards may be studied in the Workhouse quarry. 



Section in the Workhouse Quarry, Faringdon. 



ft. in. 



1 . Ragstone, quarried for lim e-burning 6 



Red clay parting, and broken Rag 4 



2. Road-stone 4 4 



3. Building-stone 3 



4. Rather loose sands, with water at the bottom. 



The top bed is the ordinary Coral Eag of the neighbourhood, as 

 seen in the last section, rather divided by clays. 

 The road- stones may be divided as follows : — 



