THE COKALLIAN SOCKS OF ENGLAND. 285 



No. 1 here contains enormous quantities of Ostrea deltoidea. In 

 different parts of the workings there are several blue shelly bands, 

 which contain most of the fossils, especially Ammonites, which are 

 very numerous. These shelly bands being of inferior quality as ore, 

 are rejected, and masses of the deltoid oysters are thrown out in 

 heaps. 



Nos. 2, 3, 4. The ore varies from 11-14 feet in thickness, being 

 generally thickest towards the west. It may be termed an oolitic 

 ironstone more or less mixed up with black argillaceous ore. It is 

 almost free from grit, and exists partly as ferrous carbonate and 

 partly as hydrated peroxide ; but the condition of oxidation varies 

 according to the amount of clay which happens to be over the beds. 

 In the oolitic portions of the stone oxidation has progressed to a 

 greater extent than in the black earthy portions, which are almost 

 in the condition of clay ironstone. The chief difference between 

 this and the granules of Abbotsbury consists in the greater abun- 

 dance of phosphoric acid. 



The fossils that we noted in the ironstone beds, though probably 

 not by any means their whole fauna, were : — 



Ammonites Berryeri (Les.). 



decipiens (Sow.), 



pseudocordatus( Bl,$H.). 



Cardium delibatuui (De Lor.). 

 Pholadomya hemicardia (Ag.). 

 Perna quadrata {Sow.). 



Pecten lens (Sow.). 



midas (DOrb.). 



distriatus (Leym.). 



Ostrea deltoidea (Sow.). 

 Serpula. 



This list, scanty though it be, serves conclusively to prove the 

 late and essentially Kimmeridgian date of the rock from which the 

 fossils are derived. The Sandsfoot grits are also essentially Kim- 

 meridgian ; and this is linked to them very markedly by these fossils, 

 especially by Pecten distriatus ; but as the Ammonites point to a still 

 later period, we are almost driven to correlate them with the oolitic 

 ore of Abbotsbury. 



The iron ore of Westbury is underlain by (5) dark green ferru- 

 ginous sand, becoming lighter and softer towards the base, but with 

 much argillaceous matter throughout, said to be destitute of 

 fossils, and having a thickness of from 4 to 7 feet. The descending 

 section was continued in a w r ell-sinking, particulars of which were 

 kindly furnished us by the manager, as follows : — 



ft. 



6. Oolitic limestone, compact where unexposed, weathering rubbly ... 28 



7. Stiff marl 12 



8. Loose sands, containing four or five beds of rocks about 1 ft. thick 



each 50 



The well left off in dark hard rock, from which the water flowed 

 abundantly. 



The only one of these beds that is exposed in the neighbourhood 

 is the rubbly oolite, whose fossils are in a rubbed and broken state, 

 the only recognizable ones being Pecten qualicosta, Echinobrissus scu- 



