406 Glaciers of North Wales. 



Cambrian mountains of Merionethshire, such as those 

 of Afon Atro, Ardudwy, and Afon Ysgethin, are marked 

 by deep grooves and striations pointing more or less 

 westward, according to the trend of the valleys. 



In ascending the valley from Llanbedr on the coast 

 south of Harlech to Llyn-cwm-bychan, the experienced 

 eye is at once attracted by the long smooth sweeps of 

 the ice-ground rocks of Mynydd Llanbedr, all trending 

 towards the west, and from the summit of Graig-ddrwg, 

 looking south towards Khinog-fawr, the same effects 

 of old glacier-ice are seen on a still grander scale. The 

 deep craggy pass of Bwlch-drws- Ardudwy is itself 

 strongly ice-grooved, while the western flanks of Graig- 

 ddrwg are covered with deeply incised striations, up to 

 the very summit of the mountain, all trending west- 

 ward. The rock-bound hollows of Llyn-cwm-bychan, 

 and other mountain turns, tell in like manner of the 

 effects of thick masses of glacier-ice, as I shall after- 

 wards explain. 



The broad flat moors and roughly hilly, but not 

 mountainous country of Cors-goch, Afon Eden, Traws- 

 fynydd, and indeed all the lower ground bounded by the 

 splendid amphitheatre of scarped mountains formed by 

 the Arenigs, the Manods, the Moelwyns, and the Cam- 

 brian steeps of Diphwys, Graig-ddrwg, Rhinog-fawr, 

 and Cefn- cam, were at the same time filled to the brim 

 with deep accumulations of snow and ice, from which 

 were discharged radiating currents of glaciers, one 

 pressing southward to swell the ice-stream that filled 

 the valley of what is now the estuary of the Mawddach, 

 another through the Pass of Afon Treweryn between 

 Arenig Mawr and Arenig Bach eastward towards Bala 

 and the valley of the Dee, there to be aided in the 

 work of erosion by the glaciers that descended from 



