I 62 



SCIENCE- G OSSIP. 



its near western end, overlooking the river, is a 

 large bluff having its rounded, top liberally scat- 

 tered with perched blocks. This lies just outside 

 the picture of Cwrn-glas-bach, to the right. The 

 marnmillated rocks of Cambrian grit show clearly 

 in the foreground, and extending high up the hill- 

 sides can be seen the rocks smoothed by the grind- 

 ing ice, although now much broken up by weather- 

 ing. The destructive effects of frost will, of 

 course, be most apparent on the lower faces of the 

 rocks which front down the valley, and these 

 broken faces unfortunately are most prominent in 

 the photograph, so the pictorial result is not so 

 striking as the reality. Evidently a tributary 



tending down the valley are a series of moraine 

 heaps, some of them of great size, placed more or 

 less concentrically, and scattered with enormous 

 blocks. This can be reached by the easier but less 

 interesting track which ascends Snowdon from 

 Llanberis. The path forks just a little distance 

 before reaching the small lake, and the right-hand 

 branch, which is a road to the abandoned copper- 

 ore workings near the lake, can be followed. 



Returning once more to Cwm-glas-bach, and 

 continuing up the Llanberis Pass, the more inter- 

 esting valley of Cwm-glas is soon reached. This 

 is separated from the former valley by the buttress 

 which is seen descending on the left-hand side of 



Photo bu~\ 



Fit 



2. Moraine heap at the foot of Cwji-glas. 

 View from the North-West. 



[A. W. Dennis. 



descended here from .the ridge above to join the 

 main glacier of the pass. We found no striae in this 

 Cwm, although I believe they have been seen there. 

 An easy ascent can be made here ; and on crossing 

 the shoulder at the top, it is only a short scramble 

 down into Cwm-Brwynog on the north-west of 

 Snowdon. 



Perhaps the most impressive evidence of the 

 vast amount of material transported by the old 

 glaciers can be seen at this spot. At the head of 

 the valley, the peace of which is now disturbed by 

 the snort and smoke of the mountain railway, 

 stand the dark and almost inaccessible cliffs of 

 Clogwyn-dur-Arddu. Sheltered in a hollow at 

 their base, at about 2,000 feet elevation, lies a 

 small blue lake. Starting from this lake and ex- 



the photograph. The rugged scenery of this grand 

 valley has throughout been modified by the glaciers 

 which once swept over its craggy slopes. 



Situated at the further end of the Cwm and not 

 far from the road is a remarkable mound, partly 

 overgrown with grass and scattered with angular 

 blocks. The most probable explanation of its 

 formation is that it was deposited at the termina- 

 tion of the Cwm-glas glacier, when, owing to the 

 amelioration of the climate, the main glacier of 

 the pass had disappeared. Eeferring to the photo- 

 graph which was taken when looking up the pass,, 

 the glacier descended from the right hand. The 

 house in the foreground shows by comparison the 

 immense size of the mound. 



Blac-ltfriars Road, London, Octbber 1900. 



