KIMERIDGE CLAY. 335 



Kimeridge beds yield RhynchoneUa inconstans, Ostrca deltoidca, 

 Exogj'ra virgula, Ammonites longispinus, etc. ; the Upper beds yield 

 Lucina viiniiscula, Discina laiissima, Lucina Uncata, Amtnotiites 

 liplex, etc. The Kimeridge Clay is best shown on the Dorsetshire 

 coast in the cliffs between St. Albans Head and Gad Cliff, and 

 again south of Weymouth and in Portland' (see Fig. 50). It forms 

 the foundation of the Isle of Portland, being exposed at the 

 northern end. The cliffs at Ringstead Bay, Kimeridge, and 

 Chapman's Pool, near Encombe, are good localities for fossils.^ 

 The ' Kimeridge Grit ' of Mr. Damon is generally regarded as the 

 top of the Corallian series (see p. 332). The Kimeridge Ledges 

 (Broad Bench, etc.) are formed by the layers of cement-stone. 



Northwards the Kimeridge Clay may be examined near Gilling- 

 ham, and south of Mere. Thence in Wiltshire it forms a wide 

 expanse of country (North Wilts Clay), between Westbury and 

 Devizes. Mr. J. K. Shopland has obtained some fine Saurian 

 remains from the brickyards at Swindon. Here Exogyra virgula 

 characterizes the upper beds, and Ostrca deltoidca the lower.^ 



In Oxfordshire (100 feet) the beds are exposed near Culham and 

 Headington.* 



In Buckinghamshire there are brick-pits at Aylesbury, Stone, and 

 Hartwell (Hartwell Clay). In Cambridgeshire the beds are well 

 exposed at Roslyn Hole, near Ely. At Knapwell and Littleport 

 thin courses of limestone have been observed. (See Fig. 68.) 



In Norfolk the beds have been exposed at Southrey near Down- 

 ham Market, and they were penetrated in a well-boring at Lynn. 



In Lincolnshire the beds extend from Horncastle and Fulletby 

 to Market Rasen and Brigg. Beautiful iridescent Ammonites 

 and many other fossils have been obtained at Market Rasen. 



In Filey Bay, Yorkshire, and in the Vale of Pickering, the 

 Kimeridge Clay is represented at the base of the Speeton Clay. 

 (See sequel.) The clay may be seen at Hildenley, and near 

 Kirkby Moorside. Its thickness at Knapton has been estimated at 

 500 feet. 



In the Sub-Wealden boring the clay was reached at a depth of 

 nearly 300 feet: its thickness appears to be about 660 feet; and 

 here Prof. Blake has suggested that the Pterocerian zone may be 

 present.'^ (See Fig. 31, p. 202.) 



At South Willingham in Lincolnshire there is hard inflammable 

 shale, locally known as " dice." " 



^ Termed the Weymouth Clay by Fitton, T.G.S. (2), iv. 212. 

 - Damon, Geol. Weymouth, 1S84; Dr. W. Waagen, Versuch einer allgemeinen 

 Classification der Schichten des oberen Jura, Munich, 1865. 

 ^ See J. Buckman, Q- J. xiv. 127. 



* Phillips, Geol. Oxford, etc. p. 324. 



* P. Geol. Assoc, vii. 358. 



^ The term ' Dicey ' is sometimes employed to indicate clay or marl that breaks 

 up into cuboidal masses. 



