326 



J. F. BLAKE AND W. H. HUDLESTON ON 



Coral 

 Bag. 



o 

 O 



O 

 O 



The 

 Coral 

 shell- 

 bed. 



o 

 O 



Section of the Crossgates Qiuirry, Seamer. 



ft. in. 

 f Soil, broken rock, and boulders of Thamnastrcea concinna{round- 



\ heads) 2 



( Oolite in a buff pasty matrix, with a bed of Rhabdophyllia at 



the base 3 



Oolite in a buff pasty matrix, with a shell-bed at the base. 

 Nerincea visurgis, Trigonia (costate sp.), Lucina, sp., Astarte 

 Duboisiana, spines of Cidaris Smithii, and a few delicate 

 fingers of Rhabdophyllia 2 8 



Thin clayparting 1 



Shelly bed, partially oolitic. Ammonites plicatilis, Nerincea, 

 Lucina, Astarte Duboisiana, many Rhabdophyllice and stray 

 fragments of Thamnastraa. ' ' Snake-bed " 1 4 



Indurated, cemented, large-sized pisolite, with an occasional 



coral. The " top hard." 1 



( The Coral shell-bed. A pale grey oolite, rather pasty ; shells 

 and corals very sparry. Fragments of Thecosmilia, often 

 prostrate, and principally in the upper portion ; Rhabdo- 

 phyllia ; a few lenticular masses of ThamnastrcBa towards 

 the base ; Pecten fibrosus, Lima rigida, L. densepunctata, L. 

 pectiniformis, Perna rugosa, Trichites, Area pectinata, spines 

 of Cidaris Smithii, very large ; megalomorphic fauna. There 

 is much comminuted shell in this bed. " The Bottom Hard." 2 

 f Bubbly pisolite, full of small Exogyrce 2 



Oolitic series, poor in shells, with an occasional brashy parting ; 



excellent lime C> 6 



Bubbly pisolite, full of small Exogyrce ; contains Echinobrissus 



scutatus, Phasianella striata, &c. ; a constant parting 6 



Fine-grained oolites, making excellent lime ; some of the upper 

 portions of the beds are rather lumpy, owing to casts of Pha- 

 sianella striata, and to nodules which may represent sponges. 

 There is one moderately shelly bed. Exogyra nana, Pecten 

 fibrosus, Gervillia aviculoides, Trigonia, Lucina, &c, to base 

 of quarry 6 



25 3 



Below this the beds are said to be fair limestones, but rather gritty. 



To any one acquainted with the formation, it need hardly be said 

 that the above measurements vary in different parts of the quarry. 

 The Coral shell-bed, for instance, varies from one to four feet, and 

 encroaches upon the subjacent oolites. 



A remarkable feature in this quarry is the development of about 

 eight feet, or, if we include the Coral shell-bed, of about ten feet or 

 more of an intermediate group, which may fairly be said to form a 

 sort of passage between what we have usually termed the Coralline 

 oolite and the Coral Rag. In most instances round the Yale of 

 Pickering, Coral Eag rests directly upon Coralline oolite, or, as in 

 the western part of the vale, merely with the intervention of two or 

 three feet of a Coral shell-bed. In these cases, where the line of 

 demarcation is very sharp, there has probably been a certain amount 

 of submarine denudation before the surface was prepared for the 

 coral-growth ; and it may be that in this district we are enabled to 

 inspect a class of beds which in other areas have been removed. 

 The fauna, too, is of a somewhat intermediate character ; but the 



