THE CORALLIAN ROCKS OF ENGLAND. 343 



of the Seven, where, including the flaggy beds at the top and the 

 bottom, they are fully, if not more than, 100 feet in thickness. Their 

 general development is best studied at the village of Cropton, on the 

 road to Rosedale. This village is situated upon the angle of a 

 plateau, some 400 or 500 feet above the sea-level. One of the con- 

 taining sides is flanked by the deeply excavated Seven gorge, whilst 

 the other faces the northern moorlands. The road from Rosed ale 

 Abbey ascends this escarpment facing the north, and crosses succes- 

 sively the Oxford Clay and the Lower Calcareous Grit. The upper 

 portion of the latter is marked by a great development of the ball- 

 beds. Immediately succeeding these, on the edge of the plateau at 

 the north end of the village, is a thick series of the " basement- 

 beds" of the Lower Limestones, here remarkable for enormous speci- 

 mens of Gcrvillia. These basement- or lower passage-beds are less 

 ferruginous than in the Scarborough district, but in other respects not 

 materially different from the beds already described at Hackness and 

 Forge Valley. Upon these rest the oolites of the Lower Limestones, 

 which are well exposed in the large quarry on the S.W. side of the 

 village. As in the great quarry of these oolites near Thornton Dale, 

 there is a face of nearly 40 feet of small-grained suboolitic limestone in 

 very large blocks. The general resemblance of the rocks to some 

 of the less fossiliferous portions of the oolite of the Upper Lime- 

 stones (Coralline Oolite) might cause even an experienced palaeonto- 

 logist to doubt the true position of these beds without the aid of 

 stratigraphical evidence, here fortunately of a most unmistakable 

 character. Still the prevalence of Gervillia, abundant in one of the 

 lower blocks, rather than of Chemnitzia, is a point of difference which 

 may always be relied upon ; doubtless a closer inspection would 

 reveal additional points. The other fossils noted were Pecten sw6- 

 fibrosus, Avicula Icevis, Trichites, Lucina Beanii*. The beds have 

 an inclination of 4° to the south. 



It is not possible in this quarry to trace the oolites of the Lower 

 Limestones upwards into the shelly series which, in this district, 

 marks the close of the Lower Limestones ; but an important step in 

 this direction is obtained at a quarry between Cropton and Caw- 

 thorne. 



Section at Whitethorn Quarry. 



ft. in. 



a. Impure flaggy limestones of a purplish colour, having, to- 



wards the base, a bed full of Ammonites. A. perarmatus 

 (type form) plentiful, A. cordatus (exeavatus) frequent, 

 A. goliathus frequent, A . plica? Ms less common 12 



b. White oolite with Cylindrites to base of quarry. (Tbese 



are the uppermost beds of the Lower oolite) 10 



22 



We here obtain a glimpse of a series intermediate between the 



* One of the workmen declared that during a period of forty years he had 

 never seen an Ammonite in this quarry. 



