EDEN VALLEY AND YORKSHIRE -DALE DISTRICT. 75 



examples of these concave rock-surfaces ; so that it is difficult to 

 avoid the conclusion that out of the Dale district the same causes 

 have been at work, producing these cup-shaped hollows among the 

 fells wherever local circumstances compelled part of the ice-sheet to 

 move in a curve. 



In the numerous instances in every mountainous district where 

 the upper parts of the ice would be influenced more by the form 

 and direction of the adjoining high land than by the general trend 

 of the valleys, there is a strong probability that wheeling movements 

 were communicated to parts of the ice. The axis of rotation would 

 of course vary in direction according to local circumstances : in 

 some cases the ice may have moved downwards in a curve as a kind 

 of undertow to the glacial stream that was crossing a col into 

 another valley ; but in the majority of cases the tangential motion 

 may have resulted from the meeting of cross currents in, or nearly 

 in, the same plane. There can be little room for doubt that any 

 such eddying of the ice, charged throughout with stones, must have 

 operated very powerfully in smoothing preexisting hollows into more 

 regularly concave coums ; and it is perhaps hardly out of the ques- 

 tion that in soft or easily eroded rocks the long-continued action of 

 the ice may have excavated many such hollows where nothing of the 

 kind existed in preglacial times. 



Origin of Drift-deposits. 



Before discussing the origin of the Eden-valley drifts in any de- 

 tail, it will be well to make a few general remarks upon the various 

 deposits which by one cause or another were left at the close of the 

 Glacial Period over the greater part of the area treated of in this 

 paper. 



In the Dale district the order of the drifts is as follows, beginning 

 with the lowest : — 



No. 1. Stiff clay, full of well- glaciated stones, apparently devoid 

 of stratification ; usually lying in the bottoms of the higher parts of 

 the main valleys, and generally found along the whole length of the 

 bottom of the branch dales, except where these are far from the head 

 of the principal valley. 



No. 2. More angular drift, containing fewer scratched stones and 

 having a more sandy matrix than No. 1. In the higher parts of 

 the valleys it becomes still more angular and loosely aggregated in 

 proportion as it nears the highest ground. It frequently extends 

 up to or above the 1800 contour in the form of an irregularly sloping 

 plain ; but thin patches of drift of the same character may be found 

 nearly up to the tops of the fells, where it seems to pass into a kind 

 of surface-wash in which an occasional scratched stone may be 

 found. This is not merely a weathered part of No. 1, but main- 

 tains its characteristics to a great depth from the surface, at which 

 no larger proportion of glaciated stones can be found than are to be 

 seen near the outside of the deposit. 



No. 3. Still more angular drift, quite devoid of stratification, very 



