760 REPORT— 1900. 



navian rocks, which bears out Mr. Marker's suggestion that the tocks not identified 

 are also from Scandinavia. 



The distribution of the Cheviot porphyrites, which occur principally as stones 

 and pebbles of smaller dimensions than the boulders of the above table, presents 

 sonae points of peculiar interest. These, besides increasing in numbers towards 

 their source, are also more abundant in the upper boulder clays and in the gravels 

 at the highest levels than in the low-level drift ; vchile, on the other hand, the 

 Scandinavian rocks, whether as pebbles or boulders, rarely occur at high levels. 

 This lends support to Mr. Lamplugh's supposition that the North Sea ice-sheet 

 attained its maximum development and reached farthest inland before the ice 

 flowing from the north-west of England had reached this portion of the coast, and 

 that the former flow shrank back as the latter gained strength. 



7. On the Glacial Phenomena of the North-east Corner of the 

 Yorkshire Wolds. By J. W. Stather, F.G.S. 



The rapid thinning away of the Drift inland from the Yorkshire coast has long 

 been recognised and variously explained. The phenomena along the margin 

 Avhere it thus thins away on the high ground are worthy of particular attention. 



North-westward from Speeton, where the drift terminates in a chain of morainic 

 mounds, the top of the chalk escarpment is more or less covered with drift as far 

 as Hunmanby, where a deep valley, now dry, breaks through the escarpment, and 

 drains inward to the central valley of the Wolds. Into the valley at Hunmanby 

 the drift penetrates for a considerable distance, in the form of boulder clay on the 

 slopes, and gravel containing many foreign stones in the bottom. The boulder 

 clay thins out long before we reach the main valley, but the gravel with foreign 

 stones intermixed with local material is present in strong force in the bottom of 

 the main valley, and it is suggested that a stream draining from the ice has flowed 

 from Hunmanby along this course. In the higher parts of the main valley, above 

 Weaverthorpe, foreign material is almost absent, except that near the head of the 

 yalley, near Luton, there is a patch of drift (shown on the Geological Survey map) 

 in which are foreign stones, derived chiefly if not wholly from the oolitic rocks, 

 quite different from the drift in the lower part of the valley. 



North of Hunmanby, at the sharp angle of the Wolds, the boulder clay again 

 rises to the crest of the escarpment in the form of a thin covering which fades out 

 gradually westward into a sprinkling of foreign stones in tlie soil. The stones 

 occur abundantly at an altitude of 400 feet above sea level at High Fordon and 

 include a large number of Cheviot porphyrites, which here as elsewhere further 

 north are most abundant at the highest levels, near the margin of the Drift. 



To explain these phenomena it seems necessary to suppose the existence of an 

 ice-sheet occupying the bed of the North Sea, with its margin only slightly over- 

 topping the Wolds and not extending far across them. It also appears, as stated 

 in a preceding paper, that the ice carrying the Cheviot rocks formed the uppermost 

 portion of the sheet. 



8. On the Age of the Raised Beach of Southern Britain as seen in Gower. 



By R. H. TiDDEMAN, M.A., F.G.S., H.M. Geological Survey. 



[Cojnmunicated with the permission of the Director-General.] 



Gower has a reputation for its caves with their bone-beds, and for its raised 

 beaches, but to the matter of its Glacial Drifts very little attention has been paid. 



Some of the caves were known to and noted by Dean Buckland.* The caves 

 were long and diligently explored by Colonel Wood of Stout Hall, and the results 

 carefully collated by Dr. Falconer.- A great number of the bones are exhibited in 

 the Swansea Museum. Mr. Starling Benson, who lived at Swansea, has left an 



' Reliquics Biluviance. 



' Falconer's Pala-ontological Memoirs, vol. ii. 



