581 
so many thousands are accumulated. If, on the contrary, it be sup- 
posed that a glacier descended southwards from Flynnon Lluewy, it 
would have entered this valley at the summit level which divides 
the waters of Llugwy from those of Llynn Ogwyn; and from this 
point, Dr. Buckland states, it may have sent two branches, one 
through the valley of the Llugwy into the vale of the Conway, and 
the other westwards into the valley of Nant Francon. 
Valley of the Ogwyn.—The Ogwyn springs from a little lake on the 
south shoulder of Carnedd Dafydd, the summit of which is 3426 feet 
above the level of the sea, and a mile of rapid descent conducts it into 
Llynn Ogwyn. If at any time, observes Dr. Buckland, the moun- 
tains of Carnarvonshire were the site of lasting snows and glaciers, 
each of the triple series of wild amphitheatres between the summit 
of the Glyder and the south margin of Llynn Ogwyn must have 
poured forth a stream of ice to unite with those descending from | 
Llynn Ogwyn into the valley of Nant Francon, over the crest of 
porphyritic slate rocks down which the Ogwyn forms a cascade where 
the high road crosses that river by a bridge. Immediately above 
this bridge the barrier of hard rocks upholding the waters of Llynn 
Ogwyn present8 a remarkable group of those rounded, dome- 
shaped bosses which Prof. Agassiz so strongly insists upon as evi- 
dences of the action of ice; and their position during the glacial 
period would have been analogous to that of those over which the 
slowly moving cascade of ice now descends from the mer de glace 
into the valley of Chamouni. ‘Their actual forms also are stated to 
be identical with those which occur beneath every similar cascade of 
ice in Switzerland. ‘These rounded rocks have been weathered, but 
quartz veins which traverse the masses and project two inches above 
the surface, are polished and rounded on the edges. The lower ex- 
tremity of the valley of Nant Francon, about one mile from the 
Penrhyn slate-quarries, is thickly studded with dome-shaped hillucks 
rising amidst the meadows like giant mole-hills, and in a position 
where they would have formed the base of the great vomitory of 
ice descending that valley. For two or three miles towards Bangor, 
particularly near the village of Bethesda, there were exposed in nu- 
‘ merous places where the gravel had been recently removed, polished 
surfaces fluted and striated in a direction parallel to that of the 
valley. Dr. Buckland saw no indications of undisturbed morains in 
the valley of the Ogwyn, but he is of opinion that they may have 
been partly obliterated by the rush of water which transported the 
northern drift, and effected a lodgement of it on Moel Faban at the 
end of the glacial period. 
Valley of the Sciant and Lianberris—This valley has its origin 
near the sources of the Gwryd, at the lofty pass of Pen-y-Gwryd, 
between the highest summits of the great Glyder and of Snowdon, 
and its course north-westward, for about eight miles from the pass 
to the lower lake of Llanberris, presents the finest examples Dr. 
Buckland has seen in Great Britain of an almost uninterrupted 
continuity of naked rocks, which have been modified by mechani- 
eal attrition, and left in a state not distinguishable from that of 
3c 2 
