12 BRITISH FOSSIL CORALS 



The corals of tlie Great Oolite are found in the Upper Ragstones underlying the 

 Bradford Clay. Near Bath large masses of Calamoplujllia radiata are associated with 

 the roots, stems, and heads of Apiocrinites rotundtis, MiU., which flourished like a 

 miniatiu'e forest on the reef, and luxiu'iated amongst the polypes until the clear water was 

 invaded by a current charged with mud, which destroyed the Encrinites and the Corals 

 also.^ 



The Coral Rag in Wiltshire is divisible into (1) Upper Calcareous Grit, (2) Coral Rag, 

 (3) Clay, (4) Lower Calcareous Grit. It is in the Coral Rag proper (2) that the Coral- 

 beds are found. Of these Mr. Lonsdale " remarks : " The irregular beds of Polyparia 

 consist of nodules or masses of crystallized carbonate of lime, which afford, invariably, 

 evidences of the labours of the Polypus ; and associated with them are others of earthy 

 limestone, which bear only partial proofs of an organic origin. The whole are connected 

 by a pale bluish or yellowish stiff clay. It happens frequently that a bed is composed of 

 one genus of Polyparia." 



In Yorkshire the Coralline Oolite is well developed, and several reefs are found at 

 Hackness, Ayton, Seamer, &c. John Leckeuby, Esq., F.G.S., of Scarborough, gives the 

 following details (see Dr. Wright, op. cit.) : — 



" In various parts of the district occupied by the Coralline Oolite around Scarborough 

 are found patches of coral-reef, sometimes occupying an area of fully an acre ; and, although 

 never attaining an altitude so high as the beds on the inclined surfaces of which they rest, 

 they are truly the uppermost beds of the formation. 



" They are sometimes fi'om ten to fifteen feet in thickness, and consist of a series of 

 layers of crystaUized coral, from eighteen to twenty-four inches in thickness, of the species 

 Tliamnastraia concinna, Goldf. (which is the Th. micraston, Phillips), each layer being 

 separated by rubbly clay and mud, in all probability the decomposition of each 

 successive reef. The rock is quarried to supply material for i-epairing the roads of the 

 district ; but it is by no means so well adapted for the purpose as the adjacent calcareous 

 grit, which, at the cost of a little additional labour, would furnish a material much more 

 durable. The crystalline coral-reef is quickly ground to powder, and its use affords 

 less satisfaction to the traveller than to the geologist, as the blocks which are stored 

 up for use along the sides of the road yield many a handsome specimen to adorn his 

 collection. 



" The largest deposit is near the village of Ayton : there are others not quite so 

 extensive ; one near the village of Seamer, another close to the hamlet of Irton, and others 

 in the neighbourhood of Wykehara andBromptora — the intervening distances being about 

 a mile in every case." 



Messrs. Leckeuby and Cullen visited the coral-reefs of the Coralline Oolite near 

 Scarborough with Dr. Wright, who writes as follows : — 



1 Dr. Wright, op. cit. 



2 "Oolitic District of Bath," ' Trans. Geol. Soc.,' 2nd ser. vol. iii, p. 261. 



