C. E. De Ranee — Surface Geology of the Lake-district. 491 



which the sea denuded the rest of the country into a gently inclined 

 plane. 



Mr. Mackintosh, in an article on the Lake-district in the Geo- 

 logical Magazine for 1865, comments on the fact, that " we 

 continually meet with a precipitous escarpment running along one side 

 of a mountain-range, the other side of which is a gradual slope ;" 

 and, furthei', that " the steep escarpments generally face the east, 

 south-east, or north-east, apparently showing that the indenting and 

 undermining current must have assailed the ancient Cumbrian 

 Archipelago from the east." His facts are undoubted, but I regret 

 I cannot agree with the inference. For if the sea formed the in- 

 dented voes of the eastern slope of Helvellyn, acting from the east, 

 it could not have also formed the precipitous slope Qit\iQioestern side 

 of the narrow Thirlmere valley, also acting from the east ; for as the 

 valley runs in a north and south direction at the foot of Helvellyn, 

 it follows that the sea must have entirely denuded away the Hel- 

 vellyn range, before it could have been exposed to the eastern 

 breakers. It seems to me rather that the western sides of the 

 gorges, or eastern sides of the hills, are steeper because they are 

 most exposed to frosts and consequently to landslips than the 

 opposite sides. My friend, Mr. Bolton, of Ulverstone, thus describes 

 the effects of a winter's frost on the disintegration of the rocks of 

 the lake district •} — " At Dow Crags sometimes may be seen a 

 spectacle of no common interest ; the immense cliffs for a consider- 

 able distance are perpendicular, and in some places overhang the 

 base, containing fissures and joints which admit moisture. . . . 

 A hard frost in winter converts all this into ice, which, by its 

 natural expansion, forces off from the parent rock large masses of 

 stone, to bound and crash along the steep descent at the foot of the 

 cliffs, .... some large blocks even entering Goat's Water 

 before their progress is arrested, the border of that small lake being 

 covered with their debris . . . several single stones .... 

 weighing about three or four tons each." 



The western sides of the valleys are more subject to landslips 

 than the eastern, not only because they are more subject to the frost 

 influence of easterly winds, but because the normal dip of the 

 Green-slate being south-easterly, the rocks of the western slopes 

 have an upward dip, causing the beds to have a tendency to slide 

 along the dip planes into the valley beneath, while the inward 

 dip of the eastern slopes defy the effect of frost to disintegrate their 

 mass. They do not, however, entirely escape ; for though less 

 ruthlessly, and less suddenly destroyed, the gi-adual wear of western 

 storms of wind and rain, round the step-like foi'm, first impressed 

 by the running brook, and finished by the glacier, into a gradual 

 slope, or rather a parabolic curve. 



At page 304 of his article, " on the Lake-district,"'- Mr. Mackin- 

 tosh mentions the eastern side of Helvellyn, as a " sea cliff," which 



^ " Geological Fragments," p. 45, ' Dow,' or ' Doe,' crags are a little west of Coni- 

 stone Old Man.— C. E. R. 

 2 Geol. Mag., Vol. II. 



