334 



J. F. BLAKE AlfD W. H. HUDLESTON ON 



wood, where they are cut through by the road. Here the oolites 

 are rather crystalline limestones towards the base, but become creamy, 

 close-grained, and thin-splitting further up, becoming, however, once 

 more crystalline and gritty as they change gradually through true 

 calcareous grits into yellow sandstones, the limestones having a shell- 

 bed towards the top. The yellow grits in their upper parts alternate 

 with hard blue rock and shelly beds, the equivalents of the Tri- 

 gonia-he&s of the Pickering quarries lying about 2 miles to the 

 south-west. Ascending the S.E. angle of Blansby-Park woods, 

 the Upper Limestones are partially revealed through the thick mat- 

 ting of undergrowth ; and, finally, the plateau at the top is found 

 to be held by an argillaceous form of Coral Rag. The thicknesses in 

 this very complete section are pretty nearly those already given, but 

 the supra-coralline beds are absent. 



These latter, however, together with the Upper Limestones, and that 

 portion of the Middle Calcareous Grits which contain the Trigonia-he&s 

 are extensively quarried at Pickering. The following section (fig. 13) 

 is the result of a careful average of the quarries on both sides of the 

 valley as far as the workmen's cottages near the third quarry on the 

 west side. North of this the Coral Rag, which is barely recognizable 

 in the quarries nearest the town, begins to make a better figure. 



Fig. 13. — Generalized Section at Pickering. (Scale 32 ft. to 1 inch.) 



Upper Division 



Middle Division. / 

 Coralline Oolite- \ 



Lower Division. 



For details of the beds see table.fp. 335. 

 Bed of Ostrea bullata. y. Line of Pisolite. 



