xv. SECTION AT SWINDON. 421 



chance of finding such except near Faringdon and Swindon. The 

 low mound south of Faringdon Folly contains sands of similar 

 appearance, and there is distinct trace of Purbeck beds at 

 Swindon. 



Dr. Fitton's account of the section at Swindon is in these 

 words a : 



' Purbeck Strata. The only indication of this member of the Wealden which I 

 found at Swindon, were detached masses of botryoidal limestone, like the middle 

 of the "Cap" in Portland, and fragments of dark brown silicified wood, fallen,! have 

 no doubt, from the top of the quarries, though supposed by the workmen to occur 

 in the midst of the stone itself. In the looser matter also, near the top of the quarries, 

 and above beds of the Portland stone, are masses including very numerous casts 

 of marine shells (apparently Lucina and Cytherea), in which the cementing sub- 

 stance has the aspect of fresh-water limestone, and is scarcely to be distinguished 

 from a stone of the same yellowish hue, within the Purbeck series, near Ridge in the 

 Vale of Wardour ; but in the latter the casts are those of fresh-water species, 

 especially Cyclades.' 



Clay occurs in detached portions above the Portland stone in the 

 great quarry at Swindon, but Dr. Fitton was not enabled to de- 

 termine the formation to which it ought to be referred. 



The result of two examinations of the quarries and other ex- 

 cavations at Swindon made by myself, was to confirm these obser- 

 vations of Dr. Fitton. No trace of incumbent sands like those of 

 Hastings. 



a Trans, of Geol. Soc. of London, Second Series, vol. iv. 1836. 



EXPLANATION OF PLATE XVI. 



1 . Vertical section of the strata in Shotover Hill. 



2. Section from Oxford to Shotover Hill. 



3. TJnio Stricklandii. Phillips. (The lighter tint indicates the restored portions at 



the extremities.) 



4. Unio subtruncatus. Sowerby. 



5. Cyrena media. Sowerby. a. Oblique view, enlarged ; b. Side view, nat. size. 



6. Paludina Sussexiensis. Sowerby. 



7. Paludina subangulata. Phillips. 



8. Paludina ornata. Phillips. 



