Vol. 65.] THE HOWGILL FELLS AND THEIR TOPOGRAPHY. 591 



None of these captures, save that of Great Ulgill and the Black Force 

 (Little Ulgill) streamy by Carling Gill, are of any serious importance. 



In the south the southward-flowing streams have not yet cut 

 through the western part of the watershed. In the east, however, 

 the monoclinal ridge has been much cut into, and very important 

 captures have resulted. Of these the most pronounced is that made 

 by the Cautley stream, and the robbery of the waters that once 

 flowed into Artlegarthdale by Backside and Wandale Becks (see 

 fig. 1, p. 590). 



The steeper grades of the capturing streams would, no doubt, 

 have caused all these captures to occur in time. As it is, there 

 is evidence of the acceleration of some by glacial agency, which 

 renders them of particular interest, and the whole evidence will 

 be considered when the glaciation is described. 



The pre-Glacial Condition of the Howgill Tract. 



The erosion by the various streams had already dissected the 

 monoclinal highland in pre-Glacial times. As before seen, the con- 

 ditions produced north of the watershed were such that the streams 

 left ridges with summits sloping gradually down northwards from 

 the watershed and with few definite minor summits along the 

 ridges. On the south side, where conditions were much more 

 complex, actual hill- summits are found : such are Arant Haw, 

 Calders, Yarlside, Wandale Head, Harter Fell, and others. 



A great feature of topographic interest in the glaciology of the 

 Howgill District is, that while some of the valleys are clearly much 

 ice-worn, others bear no sign of glacial erosion, and consequently 

 the effects of stream- and of ice-erosion can be compared or con- 

 trasted within a limited space. 



The study of valleys not appreciably affected by ice gives an idea 

 of the effects produced in this district by stream-erosion. The best 

 examples of such valleys are occupied by the feeders of Bramrigg 

 Beck. These valleys show well-marked V-shaped outlines with 

 slightly convex slopes, culminating at the head in slightly rounded 

 ridges and summits. At present, their slopes are entirely clothed 

 with vegetation, as also are the summits, and this tract presents 

 outlines like those figured by Prof. W. M. Davis in the Scottish 

 Geographical Magazine for 1906, in fig. 1 of his paper on 'The 

 Sculpture of Mountains by Glaciers.' 



No cliffs with exposed rock and no abrupt changes of slope are 

 seen in these and similar valleys of the district. There is no doubt 

 that their monotony of outline is due to the similarity of the 

 behaviour of the component rocks of the hills as regards weathering. 

 We have already noted that the Fells are chiefly composed of 

 Coniston Flags and Grits and of Bannisdale Slates. These rocks 

 are greywacke grits and mudstones, which are usually well jointed 

 and break into small pieces. Moreover, owing to the nature of the 



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