Among the Ancient Glaciers of North Wales. 13 
of the precipitous heights near the outcropping of the red conglom- 
erate. Of this, however, it is difficult to speak with confidence. 
We shall now select a new, and possibly a still more interesting 
route. At the head of the valley of Nant Francon, towering above 
Lake Ogwen and the high road from Bangor to Capel Curig, is the 
sharp and rugged peak called Tryfan — the most precipitous sum- 
mit and the finest single mountain in North "Wales. It is separated 
by a short, sharp ridge, running nearly north and south from the 
range of the two Glyders. Tryfan is an irregular continuation of 
this ridge, terminating abruptly on the Bangor road, and forming 
the western, as a spur of the Glyder Fach forms the eastern flank, 
of the romantic and secluded valley known by the name of Cwm 
Tryfan. The general level of this valley is considerably higher than 
the road, from which it is little seen, and as the approach to it is 
over broken and boggy ground, its very existence is unknown to 
multitudes of those who pass from day to day within a few minutes' 
walk of the spot. Yet it is one of the most curious in Wales. The 
explorer, on rounding the shoulder of Tryfan, comes suddenly upon 
a deep valley of gentle and tolerably regular inclination, half a mile 
wide and a mile and a half long, full, from one end to the other, of 
rounded and polished rocks of the most marked and characteristic 
aspect. They exist, not by the dozen, but by the hundred, and crop 
out from the moist turf all along the bottom of the hollow and to 
the height of several hundred feet along its sides. They are found 
up to nearly the same elevation along both sides of the valley, and 
above a well-defined line they cease altogether. Sometimes they are 
mere rounded knolls protruding through the turf and peat, but 
many of them are broad slabs and walls of living rock, hundreds of 
feet in length, every corner and angle of which has been carefully 
and elaborately rounded and polished off. More perfect specimens 
of the rochers moutonnes it would be hardly possible to imagine. 
Below the level of the glacier boundary, a sharp rock is not to be 
found, from one end of the valley to the other ; and the vast num- 
ber of the rounded knolls and shoulders, together with the general 
coincidence in their forms and in the directions of the polished sur- 
faces, affords conclusive proof that they were subjected to the action of 
one uniform, regular and constant force. The glacier which filled 
up this valley must have been, like the glacier of the Aar in Switz- 
erland, remarkable for the evenness of its surface, and for the uni- 
formity of its motion. It must have been almost a normal glacier 
— for there are no sudden contractions of its channel, no anomalous 
