Yorkshire Naturalists at Pocklington. 



Geology. — On the Superficial Deposits Mr. John W. Stather, 

 F.G.S., writes : — There is a larg-e spread of Chalk Gravel in the 

 neighbourhood of Pocklington. It was examined in several 

 shallow pits near the town and at the quarry of the Pocklington 

 Brick and Tile Works, where it was seen in section from 2 to 

 3 feet thick, resting directly on the Keuper Marl (see photo on 

 p. 272). Nearer the Wolds it is much thicker, and at Yapham, 

 two miles north of Pocklington, it is said to be upwards of 

 30 feet thick. It is composed almost entirely of slightly water- 

 worn fragments of chalk and flint, that is to say, the angles of 

 the chalk pebbles are slightly rounded, while the flint remains 

 quite sharp and angular. Diligent search was made in the 

 gravel for pebbles foreign to the district, but nothing was noted 

 beyond some fragment of Trias, Lias, and Oolite (all local), and 

 a few quartzite pebbles. It is interesting to observe that the 

 thickness of these beds of gravel varies considerably in short 

 distances, and that consequently the old surface of the Trias 

 must have been much more uneven than the present surface of 

 the country. 



The Wold hills near Pocklington are apparently free from 

 superficial deposits, but some scattered quartzite pebbles were 

 noted on the high ground near Millington and Warter (see 

 ' Naturalist,' 1904, pp. 9-1 1, 54-56). On the other hand, in the 

 bottoms of all the valleys in the Chalk, there is a deposit of 

 chalk fragments, evidently formed by the disintegration of the 

 beds in situ, and not brought from a distance. 



From the hills near Kildwick Percy extensive views of the 

 Plain of York were obtained from time to time. Westwards 

 the well-known morainic hills in the neighbourhood of York 

 could be distinguished taking the form of two great ridges, 

 crossing the plain at York and Escrick. These ridges rise to a 

 height of from 30 to 60 feet above the flat and contain boulders 

 of Shap granite and other Lake District and Teesdale rocks. 



Looking southwards, the flat low land of the valley, consist- 

 ing chiefly of warps, lacustrine clay, and sand, could be traced 

 as far as the Humber, the isolated hill of Holme-on-Spalding- 

 Moor being a conspicuous object in the middle distance. The 

 disposition of the superficial deposits on and around this little 

 hill is of great interest. The hill (Keuper Marl) rises to 150 feet 

 above the level of the sea, and is capped with gravel mosth^ 

 composed of western rocks, while the gravels on its flanks, 

 which also spread around its base arc mainly fragments of local 

 rocks. 



Naturalist, 



