592 E-E. J. E. MAKE AND ME. W. G. EEAENSIDES ON [XoV. I909, 



binding material between tbe grains, these grains become separated 

 in the course of weathering ; and grits, slates, and mudstones all 

 behave similarly, giving rise to a thin soil on which vegetation 

 flourishes and prevents the downward carriage of fragments by- 

 surface-water runnels. The material is being gradually removed 

 by soil-creep among the vegetation and superficial detritus. 1 It is 

 doubtful whether in times immediately preceding the Glacial Period 

 any rock was exposed, save only in the stream- courses ; and the 

 evidence points to the production of the present rock-exposures on 

 the hillsides in three ways : — (1) by truncation of spurs by ice; 

 (2) by corrie-glacier erosion 2 in the combes ; and (3) by the post- 

 Glacial erosion of captured streams adapting themselves to their 

 grades. 



Glaciation of the Fells. 



Our study of the ice-work of the Howgill Fells area leads us to 

 adopt generally the views of the late Mr. J. G. Goodchild, as 

 described in the letter-press and indicated on the map accompanying 

 his paper. 3 "We regard the Howgill Fells as an independent centre 

 of glaciation, the ice-field of which covered nearly the whole area 

 and had an ice-shed agreeing with the present watershed. From 

 this the ice flowed down the three slopes of the triangle, northwards 

 to the Eavenstonedale depression, westwards to the Lime, and south- 

 wards to the Eawthey Valley. This ice-sheet united in the north 

 with that which eame from the Lake District to pass eastwards 

 over Stainmoor ; on the west with that which came over Shap Fells ; 

 and on the south with that which, originating on the uplands of 

 Baugh Fell and Wild Boar Fell, extended thence down the valley 

 of the Eawthey. 



The distribution of the drifts suggests that the ice filling the 

 three depressions acted as follows : — In the north, the Howgill 

 ice in the Eavenstonedale depression was, save at the western end, 

 able to push back that of the Lake District to the north of that 

 depression. On the west, the Lune ice held its course from Tebay 

 as far south as Carling Gill. It was then pushed aside by the 

 Howgill ice and driven through the depression which the railway 

 follows from Lowgill to Grayrigg towards the Kent Valley. On 

 the south, the ice of "Wild Boar and Baugh Fells kept the local ice 

 from the short scarp-face from getting a footing in the Eawthey 

 valley, diverting it to the westward, and in one place to the north- 

 eastward. Eeasons for these views will be stated subsequently. 



1 See J. E. Marr, ' The Origin of Moels & their Subsequent Dissection, 

 Geogr. Joum. vol. xvii (1901) p. 63 ; also G. Gotzinger, ' Beitrage zur Ent- 

 stehung der Bergriickenformen ' Penck's Geographische Abhandlungen, vol. ix 

 (1907) pt. 1. 



2 After reading Willard D. Johnson's paper in the ' Journal of Geology ' 

 (Chicago) vol. sii (1904) p. 569, we would go further and speak of Bergschrund 

 erosion. 



3 ' The Glacial Phenomena of the Eden Valley & the "Western Part of the 

 Yorkshire Dale District' Quart. Journ. Geol. Soc. vol. xxxi (1875) p. 55 & pi. ii. 



