588 DE. J. E. MAKE AND MR. W. G. EEARNSIDES ON [Nov. I909, 



Bannisdale Slates, but the main mass is composed of the slates of 

 the two last-named divisions, which, notwithstanding their different 

 names, have much in common ; and, as will be shown later, the 

 uniformity of character of the rocks is of great importance in deter- 

 mining the physiographical features of the fells. 



The general relationship of the Howgill Fells to the surrounding 

 tracts and the cause of the severance of these Fells from those to 

 the west of the ' gorge ' of the Lune have been considered by one of 

 us elsewhere, 1 and need not here be discussed. From our present 

 point of view the important point is that the Fells constitute a 

 monoclinal block, with its dip-slope on the north and its scarp 

 facing south, though both dip-slope and scarp are shortened at the 

 eastern end owing to the trend of the Dent Fault. 



Accordingly, could we but fill in the hollow spaces produced by 

 valley-erosion, we should find the Fells presenting a 'desk '-structure, 

 with the gentle long slope to the north and the short sharp drop to 

 the south. The summit-ridge ranges east and west at a height 

 of about 2000 feet quite close to the southern edge. There is 

 evidence that at one time the watershedding ridge lay much nearer 

 the southern and farther from the northern margin of the tract. 

 (See PI. XXIX.) 



If the junction of the Carboniferous and Silurian rocks were 

 continued over the summits of the Howgill Fells, where the former 

 have now been removed, it would appear as a gently sloping plane 

 not far above the tops of those hills. At present, the lowest 

 Carboniferous rocks occupy the Bavenstonedale Yalley north of the 

 Howgills ; they are seen to rest on the northward continuation of 

 the hills themselves, and have a dip which is sufficient to carry them 

 over all the hills. The base would, if continued along the present 

 dip-plane, carry them some hundreds of feet above the fell-tops. 

 The sudden increase of slope of the surface, however, as it approaches 

 the Carboniferous rocks seems to indicate that there was there a 

 monoclinal flexure, and that the dip became much higher to the 

 north : hence it is probable that the present surface, if the valleys 

 were filled in, would coincide fairly closely with the original base 

 of the Carboniferous strata. 



South of the Fells a continuation of this dip would carry the 

 Carboniferous some hundreds of feet above the Eiver Eawthey ; 

 whereas, in fact, for a distance of more than 3 miles the 'Basement 

 Carboniferous Conglomerate' actually occupies the valley-bottom in 

 the neighbourhood of Sedbergh, where it is let down by a great 

 fault. The steep "southern face of the Howgill Fells is determined 

 by this fault, which trends south of east to west of north. But 

 the fault is not simple : the Geological Survey map shows three 

 faults parallel to that which brings in the Carboniferous of the 

 Eawthey Valley against the Silurian of the fells. These are pro- 

 bably step-faults, and the northernmost of them which occurs behind 

 "Winder Crook and the Knott is no doubt responsible for the shelf 

 1 Quart. Journ. Geol. Soc. vol. lxii (1906) pp. xcvi-xcix. 



