Vol. 68.] 



GLACIATION OF THE BLACK COMBE DISTRICT. 



435 



near the termination of the Damkirk Channel (half a mile east of 

 Bootle) a hollow in the drift runs to near Far End (a third of a 

 mile). South of this point, to Holegill Beck, the western wall of 

 the channel consisted of ice, and is therefore now wanting, the 

 ground on that side falling away, as a gentle slope, to the 100-foofc 

 level. The eastern wall is a steep scarp-like bank, about 30 feet in 

 height, running nearly to the 200-foot contour. South of Holegill 

 Beck it is from 40 to 60 feet high, and consists in part of boulder- 

 clay, as described above (p. 418), and in part of unstratified sandy 

 drift. 



Between Hallfoss Beck and Monk Eoss, where the bank is about 

 80 feet high, there is an excellent example of an 'in-and-out' 

 valley, the isolated ridge of drift forming, as it were, the string of 

 the bow-shaped eastern wall of the channel. The ridge resembles 

 an esker, but its origin is clear : it represents in a different medium 

 the severed spur of granite at Near Bank (p. 426), only in this case 

 the western face of the ridge had been shaped by water before the 

 advance of the ice caused the channel to be cut. With the exception 

 of one or two runnels which fall over the eastern side, the valley is 

 dry (fig. 12, p. 434). 



NearStangrah, immediately south of Monk Foss, there is another; 

 dry 'in-and-out ' valley, over 50 feet deep, and nearly as long, but 

 not so well defined, as that just described. This channel isolates 

 two small hummocks of drift, separated one from the other by a 

 low col. 



Fig. 13. — Profile section of the Tarn-Dhnples and Monh-Foss 

 Channels, and the oversteepeaed slope of Black Comhe. 



E. 



Monk Foss Tarn Dimples 



Black Combe 



Length of section nearly = 1 viiie. sea-level 



South of this spot the course of the channel becomes vague. 

 Thus from Eellside to Whitbeck, a distance of 2 miles, there 

 is evidence of a marginal drainage-channel, the floor of which^ 

 starting at the 200-foot contour, falls to near 120 feet (40 feet per 

 mile), and the western wall of which was the ice itself, except 

 where the 'in-and-out' channels were developed. 



The age of this channel was apparently about the age of the 

 Nettle Crags (late), Bramire and Corney (early) channels. 



Its comparatively low grade was doubtless due to the nature 

 of the floor upon which the ice was resting. Steeper gradients are 

 to be expected where ice rests on rocky and irregular ground, and 

 gentler gradients where it covers a softer, flatter, and more easily 

 eroded floor. 



