THE CORALLIAN ROCKS OP ENGLAND. 



369 



kinds, and also immense quantities of shells and shell-fragments, the 

 whole forming a sparkling white limestone with a splintery fracture 

 almost wholly devoid of oolite. This sort of rock often contains, as we 



Fig. 19. — Coralline Oolite faulted against Coral Rag — Hovingham 



Lime- quarry . 



s. 



Coral Rag. / j 



Coralline Oolite. 



a. Broken fissile Rag. 4-5 ft. 



b. Hard coral limestones in massive undulating beds with rounded termina- 

 tions. 14-15 ft. 



c. Coral shell-bed ; not constant as such. The lower portion, which has the 

 most shells, contains Rhabdophyllia ; the upper Thecosmilia, enormous spines of 

 Cidaris florigemma, Exogyranana, Astartc, Glypticus hieroglyphicus, and broken 

 shells. 2-3 ft. 



d. Softish oolites, which on the downthrow side are seen in their true posi- 

 tion beneath the Rag ; portions of these are seen on the upthrow pide in a 

 shivery and ruinous condition. 



have already seen at Helmsley, much flint. Commencing with the 

 western extremity of our district, not far from Hovingham, we have 

 some fine exposures of the reef-like variety, such as is represented in 

 fig. 19, in quarries on Cawton Heights, and in the village ud.ow. In 

 these places, where there is so much actual coral, without the layers of 

 intercoralline mud, the fossils are not particularly numerous or easy 

 to extract ; but we may note of course Pecten vimineus, Exogyra nana, 

 Lima pectiniformis, immense spines of Cidaris Jlorigemma, a stray 

 Hemicidaris or Pseudodiadema hemisphcericum, and in the intercoral- 

 line portion Terebratula insignis. There is, however, on Cawton 

 Heights, one most fossiliferous exposure, which, from the mixed cha- 

 racter of the fossils, has long provoked discussion as to its true posi- 

 tion. This occurs at a place, near the top of the plateau, called Sike 

 Gate (fig. 20). There is so much apparent faulting about here that it 

 is dangerous to rely upon the evidence of adjacent quarries; but in a 

 quarry 800 yards to the eastward, the surface of which is about the 

 same elevation, are displayed about 25 feet of thick-bedded oolites, 

 " soft rock," with one or two shaly partings towards the bottom. 

 Q. J. G. S. No. 130. 2 b 



