THE CORALLIAN ROCKS OP ENGLAND. 353 



of the peat. These dissolve out the calcareous matter and tend to 

 run it into doggers and calcitic layers, whilst the iron, being oxi- 

 dized, invests the sands with a coating of ferric hydrate, which 

 resists more effectually the action of the solvents. From beds in 

 such a condition it is almost hopeless to expect to obtain fossils. 



Reverting now to the line of section, we may trace these sands 

 on their dip to the eastwards, where the country begins to fall 

 towards the vale of Pickering. A fair section may be seen in the 

 "gravel-pit" (c, fig. 16), where Pecten fibrosus was the solitary 

 fossil noted. This leads us on to the instructive gorge-section of 

 Howl beck, a ravine cut by the moorland drainage on its way to the 

 deep valley of the Rye in Dunombe Park. The upper part of this 

 gash in the hillside consists wholly of the loose foxy sands, not less 

 than 60 feet thick ; but on descending the dry bed of the stream 

 which should run at the bottom, we obtain, at about the 400-feet 

 contour, the following section : — 



ft. in, 



Sandy suboolitic limestone ■. 13 



Cherty calc-grit 6 



Splintery limestone 2 6 



Here, then, after losing sight of the Hambleton Oolite, we find it 

 laid bare in the bottom of a deep gully, where its thickness and re- 

 lation to the beds above and below are ascertained with far greater 

 accuracy than in any of the quarries on the moors ; as usual, hardly 

 a fossil is to be noted. On descending the gully still further, the 

 Lower Calcareous Grit proper is also seen to be cut through to the 

 Very base, exhibiting about 80 feet of beds, to a point where the 

 water springs out, not far from the course of the river Rye. The 

 Hambleton Oolite, or limestone of the Lower Calcareous Grit, crosses 

 the river just below Sproxton-lEill bridge, near the 200-feet contour. 

 This gives a dip of about 1 in 30, equal to 2° nearly, in a direction 

 E. by N". from its section in the ravine of Bridge Howl. Judging 

 from a cursory survey of its occurrence in the bed of the river, it 

 appears to be still diminishing in this direction. On the other side 

 of the river it may also be seen in the neighbourhood of Rievaulx 

 Abbey. On the road from Helmsley, descending the hill, is a quarry 

 of this limestone, with Ammonites plicatilis, Millericrinus echinatus, 

 and abundance of Echinobrissus scutatus. 



If we take the maximum development of the three subdivisions of 

 the Lower Calcareous Grit in this region, we obtain something like 

 the following: — 



ft. 



1. Lower Calcareous Grit proper, Whitestonecliff 120 



2. Hambleton Oolite, Kepwick 50 



3. Middle, or Wass-Moor Grit 60 



230 



No. 4. This division consists of the Coralline oolite and Coral 

 Rag, the former of which is especially well developed, along the line 

 Q.J.G.S. No. 130. 2 a 



