Vol. 65.] THE HOWGILL PELLS AND THEIR TOPOGRAPHY. 589 



of dip-slope which is preserved upon these hills at a much lower 

 level than that beyond the summit-ridge to the north. 



Another fracture apparently occurs north of the main water- 

 shed, crossing the district from west to east from the Carling Gill 

 Valley to Ellergill Sike, forming a step in the dip-slope, and by its 

 shattering determining a row of cols more or less parallel to the 

 main watershed. 



The shatter-belt x of this fault is very wide, and is marked along 

 its course by haematite staining, probably introduced from above 

 when the basement-conglomerate covered the tract. 



The section drawn from the Calf to the river Lune along the hill- 

 tops west of Bowderdale (PI. XXXI, fig. 2) shows the character 

 of the displacement and the general characteristics of the old Pre- 

 Carboniferous dip-surface in this district. 



The movement which caused the present elevation of the Howgill 

 Fells, the nature and age of which have been referred to by one of 

 us elsewhere, 2 was apparently so widespread that it caused but 

 little warping of the northern Carboniferous dip-slope just discussed, 

 and the consequent displacement of the Silurian platform may here 

 be neglected. As the basal Carboniferous rocks were removed, the 

 bared Silurian rocks must have appeared in the form of the mono- 

 cliual block in which we now find them. 



On whatever rocks the rivers developed upon the Howgill tract 

 were initiated, the retardation of erosion when Silurian rocks were 

 encountered would be so considerable that the streams occupying 

 the thalweg of the waters in the Bavenstonedale Valley, along the 

 soft rocks of the basal Carboniferous, must have lowered that tract 

 considerably before the Howgill streams could accomplish much 

 erosion. 



Similarly the Bawthey was eroding in weak rocks, and the Lune 

 south of Tebay perhaps keeping open its course along a line of 

 weakness during uplift. Consequently the triangular stretch of 

 whatisnowlow ground surrounding the Howgill Pells was lowered, 

 leaving the upland monocline in its midst. Upon this ceutral 

 block of the Howgill Pells, the drainage-lines were therefore 

 determined by (a) the ridge between dip-slope and fault-scarp as 

 watershed, and (6) the three depressions of Raveustonedale, the 

 Lune below Tebay, and the Bawthey Valley and its northern 

 feeder Sally Beck, which extends to a col looking over to Baven- 

 stonedale. 



A series of long streams were developed on the dip-slope and 

 flowed northwards. Of these, Tebay Gill and Ellergill and some 



1 I have elsewhere described a series of shatter-belts as occurring among the 

 Lower Palaeozoic rocks of Lakeland, along tear-faults ; but the term was not 

 then defined, and there is no reason to confine it to the shattered tracts along 

 tear-faults. I may define a shatter-belt as ' a belt along which the rocks have 

 been shattered by movement into large and small fragments, the rocks on 

 either side not necessarily being permanently displaced, although they are 

 frequently so displaced.' — J. E. M. 



2 Quart. Journ. Greol. Soc. vol. lxii (1906) pp. xcvi-xcix. 



