THE CORALLIAN ROCKS OF ENGLAND. 349 



Thus between Pickering and Helrasley there is considerable iden- 

 tity of type in the Corallian beds, with certain gradual changes, 

 which become more marked towards the west. Throughout, the 

 dips are southerly. Helmsley, however, which lies in a well-marked 

 synclinal, is the turning-point in the inner rim of the long elliptical 

 belt of Corallian strata. An imaginary line passing north-west 

 through this town may roughly divide the Pickering district from 

 that of Hambleton. 



3. The Hambleton District. 



The area included under this title extends considerably to the 

 westward of the district included in the sketch map fig. 10 

 (p. 316), and, though not exactly typical for Yorkshire, sums up and 

 includes almost all the beds known to occur on a large scale in the 

 county. "We commence with the wide circle sweeping round the 

 north-western and western escarpments of the Hambleton Hills by 

 Arden Moor and Black Hambleton, one of the highest points in the 

 district, then by Whitestonecliff and Poulston Scar, till the beds 

 gradually drop to the east by Byland, Wass, and Ampleforth. The 

 natural continuation here would be sought in the Howardian Hills ; 

 but a great valley, the result of erosion acting upon a line of com- 

 plicated dislocation, completely severs these latter. Through this 

 valley, by Coxwold and Gilling, the railway from Thirsk to Malton 

 passes easily from the vale of Thirsk to the more secluded vale of 

 Pickering. The Corallian beds on the south of this erosion consti- 

 tute our fourth division, viz. the Howardian District. 



Returning to the northern side, within the semicircle thus marked 

 out we have higher beds continually developed as we approach the 

 interior curve, which girdles the bay of Ximmeridge Clay, whose 

 western extremity just reaches the meridian of Helmsle}^. In the 

 annexed figure a general section is given of the whole series from 

 the Hambleton escarpment to the vale of Pickering, immediately 

 east of Eye House (below Helmsley), where the railway cuts a few 

 feet of Kimmeridge Clay, which is there covered by a superficial 

 wash of moderate thickness. 



No. 1 in this section is the Lower Calcareous Grit proper, speak- 

 ing in a petrological sense ; it forms the parapet, as it were, of the 

 western escarpment between Eoulston Scar and Whitestonecliff, 

 where it has a thickness of about 120 feet. In this exposure the 

 lower portion is seen to consist of a peculiar ferruginous sandstone, 

 which seems to be developed at the expense of the Oxford Clay, 

 here very thin, and no doubt corresponds to an earlier period than 

 the one with which we are now dealing. There are about 20 feet of 

 this peculiar ironstone at the base ; and the rest of the beds are 

 alternations of hard and soft grits, with large doggers, fucoid (?) 

 growths, and small nests of fossils ; but in general both cliff and 

 moor are so beaten by the winds and storms of ages, that little 

 remains of an organic nature on the exposed portions of these rocks, 



