1850.] AUSTEN SANDS AND GRAVELS OF FARRINGDON. 461 



Kimmeridge, and that it is this portion of the oolite series which here 

 underlies the gault. 



The sands at Alfred's Hill were carefully examined by Mr. Sharpe 

 and myself at a subsequent visit. 



From Shrivenham the party proceeded together in the direction of 

 Bourton. Between the Canal and the Railway is a large brick-field 

 worked in a strong blue clay, and which from its relative position 

 with the coral rag we considered as Kimmeridge. Beyond the Rail- 

 way the ground rises ; the lower part of Bourton Hill consists of the 

 same blue clay, but towards the upper part of the village a mass of 

 thin-bedded freestone sets on. The whole of the summit of the hill 

 is so composed, and on the road leading S.E. a large quarry exposes 

 more calcareous and thicker beds. The fossils from these beds were 

 few, and only internal casts : Trigonia incurva ? Sow., Cardium dis- 

 simile, Sow., and a large Pleurotomaria. 



It is stated in the 'Outlines of the Geology of England,' p. 181, 

 ** that in the interval from Abingdon to Seend, the Portland beds, re- 

 posing on Kimmeridge clay, are only seen at one point, namely at 

 Swindon;" and Dr. Fitton does not notice it at any place between 

 those here indicated. There can be no question, however, that the 

 beds which cap the hill at Bourton belong to the Portland oolite. 



From Bourton to the foot of the chalk escarpment is an interval 

 of about two miles, in which there is no opportunity of observing 

 the nature of the beds, but which is evidently a clay, and therefore 

 most probably an extension of that of the lower part of Bourton Hill. 

 The gault with the overlying upper greensand are seen in consider- 

 able thickness at the foot of the chalk escarpment at Little Hinton ; 

 thence our route lay along the under range of upper greensand through 

 Wanborough to Swindon. 



In applying the names of Gault and Upper Greensand to the beds 

 which underlie the chalk along the line here described, it is not in- 

 tended to convey the notion that any separation can be traced between 

 two well-defined groups, or that even any true sandy beds occur ; in- 

 deed there is no name in the whole series of geological formations so 

 purely conventional as that of Upper Greensand ; — what is meant is, 

 that the beds below the chalk here represent the upper greensand 

 and gault of those parts of the cretaceous area where those groups 

 are distinct. The form this part of the series here takes, from below 

 upwards, is that of a dark blue argillaceous mass, passing by a gradual 

 increase of sandy particles into a dark argillaceous sand ; and by the 

 substitution of calcareous matter for the argillaceous, there is a slow 

 passage into the lower chalk. 



There are one or two features connected with the chalk escarpment 

 which may yet deserve notice. The highest point, Uffington Camp, 

 appears to rise no higher in the series than the chalk without flints : 

 the steep angle of the slope of the escarpment, its very sinuous out- 

 line whereby the numerous picturesque coombes are produced, the 

 great volumes of water which burst out at its base, are points of much 

 interest, the latter especially. Great blocks of flint-breccia and grey- 

 wether-sandstone are scattered, not only over the table surface of the 



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