THE COKALLIAN ROOKS OF ENGLAND, 359 



the before-mentioned red clay. At quarry / it is only 6 feet thick. 

 Whether this diminution is duo to denudation of the upper surface 

 or to thinning on the rise is not certain ; but, as the Coralline Oolite 

 clearly thins on the rise, this subdivision may also be affected. In 

 the easterly continuation of this escarpment, outside the section, the 

 Eag at the Nunnington cutting is only 8 feet thick. On the whole 

 we are inclined to conclude that the attenuation is due to thinning, 

 and that at Oswaldkirk we perceive the middle of a partially lenti- 

 cular mass of Eag thinning towards the east and the west. In 

 quarry / an old weathered surface exhibits a fine arabesque of Theco- 

 smilia in an upright position, with very large specimens of Chem- 

 niizia. Exogyra nana, Pecten vimineus, Lima Iceviuscula, Lima 

 pectiniformis, and Cidaris florigemma (spines) are plentiful. Tham- 

 nastrcea aracJmoides and Stylina tubidifera noted. 



Finally, there are traces of the Eag at the east end of Amplcforth- 

 Beacon quarry ; but it is probably no longer continuous. 



The Upper Calcareous Grit (5) of this district assumes consider- 

 able importance, being fully 30 feet thick on Oswaldkirk Bank top : 

 it extends over the escarpment with a N.N.E. slope till it insensibly 

 passes under the Kimmeridge Clay of the vale of Pickering. Indi- 

 cations of its presence may be noted between Ampleforth-Beacon 

 quarry and quarry f; but a field or two east of the latter it has 

 entire possession of the surface of the plateau, and holds it also 

 between Oswaldkirk and Nunnington cutting, the escarpment no 

 longer sinking materially in this direction. Between the latter 

 points, eastward of the section fig. 17, there are several instructive 

 exposures. 



In the Nunnington cutting wo have the following. The dip at 

 the bridge is about 5° N. |- E. 



ft. in. 

 Surface accumulations and ferruginous gritty brash forming the top of 



the Upper Calcareous Grit 7 



Upper Calcareous Grit in solid blocks 25 



Coral Rag. Block coralline and sparry limestones, with Thccosmilia and 



ThamnastrcBct : many fossils.... 8 



Coral shell-bed. A peculiar white oolite, exhibiting in some places 

 reliefs marked by an occasional coral, spines of Cid. florigemma, and 

 more rarely of Hcmicidaris, Natica clio, Ncrincea, Chcmnitzia (short 

 var. of heddingtonensis ?), and numerous Exogyra nana ; the upper 



part is the most fossil iferous 3 6 



Unfossiliferous shivery oolites 



In a limestone quarry a few yards to the west of the cutting 



there is already some difference. . 



It. in. 



Upper Calcareous Grit (base only seen) 4 



Coral Rag, extremely fossiliferous 7 



Coral shell-bed. An oolite, with occasional spine of .Cid. florigemma ... 2 (> 

 Coralline Oolite. 



Bed of oolite limestone 2 6 



Suboolitic shelly bed, with Gcrvillia aviculoides, Ccrithium muricatitm, 



Trigonia (clavellate sp.), &c 1 



Shivery oolites, having the character of thick-bedded limestones, con- 

 taining occasional specimens of Ammonites •plicatilis, but not very 

 rich in shells. 



