THE CORALLIAN ROCKS OF ENGLAND. 



361 



of every thing from the Lower Calcareous Grit of Cauklass Bank, 

 through the passage-beds into the Coralline oolite, and thence 

 through the Cqral Rag into the Upper Calcareous Grit, may be 

 obtained. The features of the Oswaldkirk escarpment are to a 

 certain extent repeated, and the reverse or dip slope, facing the 

 north, is soon covered over by Upper Calcareous Grit, At the 

 quarry near Cauklass End there is a small univalve-bed in a com- 

 pact limestone, similar to one at Pickering, and perhaps on about 

 the same horizon. We have determined the following species : — 



Cerithium inornatum, Buvig. 



limaeforme, Bom. 



muricatum, Sow. 



Cerithium, sp. (cf. virdunense, 



Buvig., xxvii. 13). 

 Phasianella striata, Sow. (juv.). 

 Rissoa ? sp. 



The upper portion of this quarry contains a remarkable shell-bed, 

 whose true position in the series is not easily fixed, though it would 

 seem to be somewhere on the boundary line between the Coralline 

 oolite and Coral Rag. Chemnitzia, Nerincea, and Astarte ovata are 

 the prevailing shells ; here was found the fine clavellate Trigonia 

 recently figured and described by Dr. Lycett as Trigonia Hudlestoni. 



4. District of the Howardian Hills. 



The fourth district into which we have divided the Yorkshire 

 Corallian area includes the inner portion of the range of hills which 

 bounds the vale of Pickering on the south-west (see Map, fig. 10, p. 

 316). This range, consisting wholly of Jurassic rocks, is completely 

 buried beneath the still loftier Chalk Wolds a few miles east of the 

 Derwent valley, which divides the Howardian range into two very 

 unequal parts. The stratigraphy of the district is much more com- 

 plicated than that of the far more massive Tabular range, already de- 

 scribed in the three preceding sections, and is therefore of little 

 assistance to us in judging of the sequence of the various rocks. The 

 following arrangement is therefore based principally on palaeonto- 

 logical, and sometimes on petrological data ; and no attempt at a 

 connected topography is made. 



"We should naturally expect that the highest beds throughout this 

 range would be found along the northern edge of the hills, as they 

 are generally along the southern edge of the Tabular range; but this 

 is by no means the case either east or west of the Derwent. The 

 beds crop out sometimes to the south and sometimes to the north. 



1. West of the Derwent. Lower Calcareous Grit and Passage- 

 beds. — We shall first describe the development of the Corallian rocks 

 on the west of the Derwent, and, beginning at the base, take our first 

 illustrative section from the Park quarry, Castle Howard. There is 

 a steady dip in this quarry about N.JST.E., which is the normal dip 

 of the beds in the Howardian Hills, judging from the general out- 

 crop. Here we may trace the beds down to the Oxford Clay. The 

 Park quarry shows a face of some 12 feet of a light, porous, and 

 thoroughly typical calc-grit. Its fossil contents too are equally 

 typical ; it is remarkable for large Aptgchi, and for the phrag- 



