THE CORALLIAN ROCKS OF ENGLAND. 327 



abundance of the spines of Cidaris Smithii serves to connect it with 

 the overlying Rag. 



Of the identity of the beds here exhibited with those of the upper 

 series of limestones in Forge Valley we have no doubt ; and the frag- 

 mentary oolite at the top of the Filey section is possibly on the same 

 horizon, whilst the oolite on Scarborough Castle Hill belongs, as we 

 have seen, to the Lower Limestones. Towards the west we have 

 traced this oolite as far as Brompton still retaining similar characters. 



The rubbly beds containing corals, to which alone we apply the 

 name of Coral Rag, taking the term in a petrological sense, are in 

 this, as in other districts, very distinct from the beds below. They 

 also present some features which are peculiar as compared with 

 similar beds elsewhere. The exposures are very numerous all along 

 the edge of the vale, and, from the abundance of fossils, very at- 

 tractive. 



At the Crossgates quarry we just catch a glimpse of the Coral Rag, 

 its most easterly exposure, though it has been proved beneath the 

 superficial accumulations at the Cay ton Waterworks still further to 

 the eastward. On the other side of the road a ten- or twelve-foot 

 face used to be worked for roadstone, the dip of about 3° S.S.W. 

 bringing the upper beds into lower positions in a southerly direction. 

 Even in Crossgates quarry itself " Roundheads,'' *. e. boulders of 

 Thamnastrcea concinna, were found on the top of the Coralline 

 oolite ; but they became scarcer in the direction of the outcrop. 



The position of the coral-bearing beds may be seen at various 

 points near Ayton. About a mile to the east of the village, on the 

 Scarborough road, we have, to a certain extent, a repetition of the 

 Seamer (Crossgates) quarry, viz. the Coralline oolite, showing about 

 eight feet on the north side, surmounted by a bed of oolite brash, 

 and then by true Coral Rag, which is in force on the south side of the 

 road. 



The character of the Rag in a quarry at the base of Yetman- 

 dale should also be noticed. The greater part of it consists of Rag 

 rubble, broken up and deposited in beds about two feet in thickness, 

 with softer partings, becoming more crystalline and solid towards the 

 top, and graduating into or surmounted by two feet of fissile shelly 

 oolite. In another part of the same pit the whole thickness is ir- 

 regularly filled with thick-bedded crystalline coral. There are two 

 things to notice here : — (1) the irregularity of the coral growth ; (2) 

 the surmounting of the Rag by oolite. With regard to the first, 

 Mr. Leckenby appears to consider that the patches of coral reef, the 

 crystallized remains of which form the Rag, are detached and not 

 continuous. It would necessitate an accurate survey of the whole 

 ground to say how far this view is correct, or whether, on the other 

 hand, there is not something like a belt of Coral Rag on the dip for 

 some considerable distance on both sides of the village of Ayton. 

 There certainly is great irregularity of development as seen in this 

 and other Rag-quarries, where the coral itself is parted by masses of 

 a peculiar chalky rock, the calcareous debris of powdered coral, which 

 contains the bulk of the fossils. With regard to the second point, 



