422 Glaciers. 



pools. Tiny moraine mounds scattered about, tell of the 

 last remnants of ice ere the shrunken' glaciers finally 

 melted away in the upper recesses of the mountain. 



From the summit of Snowdon three of the old 

 glacier valleys may be seen that radiate from the 

 mountain. On the east, the magnificent amphitheatre 

 of Cwm-glas and Llyn Llydaw, with all its striated 

 roches moutonnees, moraine mounds, and numerous 

 perched blocks ; on the south, the deep glen of Cwm-y- 

 llan, with its ice-worn surfaces of rock on the sides of 

 the hills, in which, just below the peak of Snowdon, 

 there is a symmetrical moraine about half a mile in 

 length, formed in the latter days of the glacier, that 

 once flowed down to join the larger ice-stream that 

 descended through Nant Grwynant and the valley of 

 Llyn-y-ddinas, and so onward to Traeth-mawr below 

 Beddgelert. Just below the peak lies the broad pre- 

 cipitous cirque of Cwm-y-clogwyn, in which may be 

 faintly seen the terminal moraine of a minor glacier, 

 partly circling the pool of Llyn-goch ; and, descending 

 by the path to Llanberis, a vast moraine heap lies 

 immediately north and west of the deep-set tarn of 

 Llyn-du'r Arddu. 



It would be easy for me to give a similar descrip- 

 tion of the large glacier that filled the valley of 

 Nant-ffrancon, and flowed onward to where Bangor 

 now stands, where, as a terminal moraine, it deposited 

 those beautiful wooded mounds that form the park of 

 Penrhyn Castle. Further up the valley, beyond Ogwen 

 Bank, the river is barred across by striated grits, dotted 

 with erratic blocks, and high above is the craggy 

 tributary valley of Cwm-graianog. Its whole length 

 is not over half-a-mile, and at its mouth, above the 

 steep descent to Nant-ffrancon, a small but beautifully 



