§ 16. 



THE STONESFIELD SLATE. 507 



" The quarries near Birdlip also exhibit the Inferior Oolite, and the 

 remainder of the road to Gloucester rests upon the Lias. 



" If an Artesian well were sunk at Swindon New Town, it would pro- 

 bably pass through the above-mentioned strata, from the Kimmeridge 

 clay to the Lias, in the same order in which they are passed over by 

 the Irmin Way, reaching the surface of the Lias at a depth of about 

 1000 feet." 



16. The Stonesfield slate. — I have already stated 

 that the zoological characters of the Oolite and Lias are 

 decidedly marine; the interspersions of fresh-water and 

 terrestrial sediments having been produced by the accumu- 

 lation of materials brought down by streams and rivers 

 into the sea, and transported by currents to a distant part 

 of the oceanic basin. Unlike the organic remains of the 

 Wealden, the terrestrial and fresh-water productions are 

 mingled with marine plants, shells, and fishes ; thus, while 

 the Chalk consists of the bed of a deep sea with scarcely 

 any intermixture either of land or fresh-water debris, and 

 the Wealden of a delta in which but very few marine exuviae 

 are imbedded ; the intercalations in the oolitic series present 

 a combination of these characters, of which the Stonesfield 

 strata afford a highly interesting example. 



Stonesfield, a small village near Woodstock, about twelve 

 miles north-west of Oxford, has long been celebrated for 

 the fossils imbedded in its slaty limestone ; bones and teeth 

 of large reptiles, and of fishes, and other remains from this 

 locality, were described and figured byLhwyd, a century ago.* 

 The " Geology of England and Wales," by Messrs. Conybeare 

 and Phillips, which every one must regret has not been 

 continued and completed by the highly-gifted author who 

 survives, contains a description of the Stonesfield strata, 

 and a brief enumeration of the fossils which they inclose. 



On my discovery of the fluviatile origin of the strata of 

 Tilgate Forest, I was led to institute a comparison between 



* Lithophylacii Britannici Ichnographia. 



