342 J. F. BLAKE AND W. H. mTDLESTON ON 



not far removed from that of the Lower Coral Rag of Hackness. 

 The silicification of the oolite seems also an important feature in the 

 Lower Limestones here, as we shall see further west. The limestones, 

 as usual, are not very fossiliferous ; but we noted the following — ■ 

 Pleurotomaria Munstsri, Ghemnitzia heddingtonensis (rare), Gylin- 

 drites elongatus, Anomia radiata, Avicula ovalis, Lima frag His, Pecten 

 fibrosus, Gervillia aviculoides, Trigonia (clavellate species), Lucina 

 Beanii, E hinobrissus scutatus. In an adjoining quarry about 35 

 feet of oolites are seen, of which 17 feet lie above those last measured. 

 Towards the base there are abundance of Gervillia ; and towards the 

 top, oiJS T erincea. The several beds have red clay partings and contain 

 also Exogyra nana, Perna quadrata, and plates of Astrogonium. 



These quarries are close to an escarpment overlooking a deeply 

 excavated glen which runs far up into the hills to the northward ; 

 here the Lower Limestones may be traced down into the Lower 

 Calcareous Grit, which occupies the slopes of the glen, and also 

 much of the surface of the high ground where the limestones 

 have cropped out ; but far away to the north the limestones come 

 in again. This glen debouches into the vale at the beautifully situ- 

 ated village of Thornton ; and on the opposite side is another large 

 quarry in the Lower Limestone showing a face of nearly 40 feet of 

 rock, mostly soft, white, small-grained oolite of a somewhat sandy 

 nature. Upwards these oolites may be traced, in a northerly direc- 

 tion, on the road towards Highfields, well into the Middle Calcareous 

 Grit. In an opening for road-stone we observed the following 

 section : — 



ft. in. 



( Soil and shattered stone 5 



Flaggy calcareous sandstone 4 



Hard blue rock, slightly oolitic, with Ammonites 



plicatilis 1 6 



Flaggy calcareous sandstone, with some oolite ... 5 



Hard blue rock 1 2 



Flaggy sandston e, with A vicula expansa 6 



f Principal shell-bed, an impure suboolitic lime- 

 Top of Lower J stone 1 3 



Limestones. 1 Flaggy parting 3 



[Lower shell-bed (base of quarry) 1 6 



Middle Calca- 

 reous Grit. 



20 2 



These shell-beds appear to mark the top of the Lower Limestones 

 in this district, and form a notable horizon likewise on the other 

 side of Pickering. The shells are fine, and not different from those 

 of the Coralline oolite proper, except as regards the greater abun- 

 dance of Gervillia. The following were noted — Belemnites abbre- 

 viate, Ghemnitzia heddingtonensis, Perna quadrata, Avicula ptero- 

 pemoides, Pecten lens, P. fibrosus, Anomia radiata, Trigonia (cla- 

 vellate sp.), Lucina Beanii (aliena ?). 



To the west of Pickering the Lower Limestones spread out over 

 a great area and become of considerable importance, capping the 

 hills for many miles. They are evidently very thick on the meridian 



