that afford the S tone sfie Id- slate. 413 



English geologists. And I have no doubt that more extensive 

 examination would have removed all uncertainty upon this subject 

 from the mind of my friend Mr. Constant Prevost,* with whose 

 candour and accuracy as an observer, I have had frequent oppor- 

 luiiities of becoming acquainted. 



The only question in the present case is, whether the Stonesfield 

 slate is to be considered as one of the group of strata constituting 

 the great oolite .' — in short, whether it is inferior to the Oxford 

 clay ? The precise place of the slate, and the form of its equiva- 

 lents in other quarters, are distinct considerations : and the evi- 

 dence in proof of its true situation might be complete, although 

 no similar deposit had been detected in any other district. But, 

 though no other assemblage of fossils like that of Stonesfield has 

 yet been found among the oolitic strata, slaty limestone, holding 

 nearly the same geological place, is well known to occur in several 

 other localities — where the strata are not more difterent from each 

 other than the distant portions of other groups, respecting the 

 identity of which no doubt has ever been entertained. 



In crossing the country, from Oxford to Stonesfield, the Oxford 

 clay with its characteristic fossils is first observed ; and this is 

 succeeded by the cornbrash, — the uppermost stratum of the great 

 oolitic group, which is seen beneath the clay in several quarries on 

 the sides of the road to Woodstock and Blenheim. The aspect of 

 the country hereabouts accords perfectly with that of a series of 

 continuous strata, rising with a very gentle inclination towards the 

 north west; nor did I observe anything in the vicinity of Stones- 

 field leading to a suspicion that the strata upon which the vil- 

 lage itself is placed, were not the same with those in its imme- 

 diate neighbourhood. + The village is situated on the brow of one 



• See Annales des Sciences Naturelles, torn. 4. 1825. p. 389. 



+ The published maps of Oxfordshire express the natural features very im- 

 perfectly ; and, unfortunately for Geology, the Ordnance Survey has not yet 

 been engraved. But on examining the large unpublished maps at the Ord- 

 nance drawing-room, I could see nothing indicating any departure from the 

 general structure in that which represents the country around Stonesfield ; 

 though in several other cases, the features of the Ordnance maps correspond 

 with the variations of the strata. 



