362 Notes on the Fffecis produced hy Glaciers^ ^c. 



jects where the valley bends a little. For the lower 1000 

 feet (estimated, I think, correctly), the marks left by the glacier 

 are very distinct, especially near the upper limit, where there 

 are boulders perched on the bosses of rock, and where the 

 scores on the nearly vertical faces of rock are, I think, more 

 distinct than any others which I saw. These scores are gene- 

 rally slightly inclined, but at various angles, sea-ward, as the 

 surface of the glacier must formerly have been. But on one 

 particular face of rock, inclined at an angle of somewhere 

 about 50°, continuous, well-marked, and nearly parallel lines 

 sloped upwards (in a contrary sense to the surface of the 

 glacier) at an angle of 18° with the horizon. This face of 

 rock did not lie parallel to the sides of the main valley, but 

 formed one side of the sloping end of the mountain, over and 

 round which, the ice appears to have swept with prodigious 

 force, expanding laterally after being closely confined by the 

 shoulder above mentioned. At this point, where the glacier 

 has swept to the westward and has expanded, its surface 

 seems in a short space to have declined much ; for on a hill 

 lying about a quarter of a mile NW. of the shoulder, and 

 forming a lower part of the same range (it stands S.SE. of 

 the Victoria Inn, and has a reddish summit), the marks of the 

 passage of the glacier are at a considerable lower level. At 

 the very summit, however, of this hill, several large blocks of 

 rock have been moved from their places, as if the ice had 

 occasionally passed over the summit, but not for periods long 

 enough to have worn it smooth. 



I cannot imagine a more instructive and interesting lesson 

 for any one who wishes (as I did) to learn the effects produced 

 by the passage of glaciers, than to ascend a mountain like one 

 of those south of the upper lake of Llanberis, constituted of 

 the same kind of rock and similarly stratified, from top to 

 bottom. The lower portions consist entirely of convex domes 

 or bosses of naked rock generally smoothed, but with their 

 steep faces often deeply scored in nearly horizontal lines, and 

 with their summits occasionally crowned by perched boulders 

 of foreign rock. The upper portions, on the other hand, are 

 less naked, and the jagged ends of the slaty rocks project 

 tlirough the turf in irregular hummocks ; no smooth bosses. 



