582 
the mountain troughs now mouided by the action of Alpine gla- 
ciers. The crest which divides this valley from those of Nant-y- 
Gwryd and Nant Gwynant, forms, Dr. Buckland is of opimion, the 
highest centre in Snowdonia, from which three glaciers may for- 
merly have descended the valleys through which the Sciant, the 
Gwryd and the Gwynant now flow. At the point where the road 
from Llanberris to Capel Curig crosses the highest point im the 
pass, the rocks are shaped into flattened domes and oblong bosses, 
but they are too much weathered to exhibit any striz or flutings. 
For about three miles from the crest of the pass to the church of 
Llanberris, a kind of under-terrace which divides the river from 
the crags overhanging the left flank of the valley, presents a suc- 
cession of low dome-shaped and rounded projections, and of fur- 
rowed, fluted, striated and polished surfaces. The two most pro- 
minent localities are the rocks behind the office of the copper- 
mine, and between the great water-wheel at the slate-quarries and 
the lower end of the lake: these phenomena were observed and 
sketched by Mr. Underwood in 1824. A third locality, of easy ac- 
cess, is a rock immediately above the bridge, about 200 yards from 
the Victoria Hotel. ‘There are no traces of morains in this yalley, 
except at its lower extremity, about one mile below the north- 
western end of the lake, where innumerable blocks are scattered 
over a high plain near the village of Cwm-y-Glo, and rest on a sub- 
stratum of gravel. 
Valley of the Gwyrfain or Forrhyd river.—The Gwyrfain has its | 
origin in the lake Llyn-y-Gader, situated in the high table land 
which divides this valley from that of Bed Gellert. On the east 
bank of the lake Llyn-y-Gader is a cluster of dome-shaped bosses, 
and other similar examples abound on the adjacent broad and ele- 
vated mountain plain of Llyn-y-Gader, between Llyn Cwellyn and 
Bed Gellert; and overhung by the highest summit of Snowdon 
on the east, and by the lofty mountains of Y Carn and Mynydd 
Mawr on the west. This plain, Dr. Buckland is of opinion, may 
have formed during the glacial period a field of ice, the two chief 
outlets of which were Llynn Cwellyn on the north and Bed Gellert 
on the south; while a third vomitory, he conceives, may have passed 
westward from the highest peak of Snowdon along the valley of the 
Nantel. 
Valley of the Nantel or Lyfni.—At the upper end of this valley, 
close to the copper-mine of Drws-y-Coed, a polished surface of the 
slate rock exhibits flutings and striz in the normal position of these 
phenomena, namely, parallel to the direction of the valley. At 
a series of slate-quarries on the north margin of Lake Llyniau, the 
surfaces from which the drift had been lately removed were also 
polished, fluted and striated with lines, in the same direction as 
that of the valley, or from east to west. The Dorothea Quarry, 
near Tal-y-Sarn, affords a splendid example of these surfaces, where 
the deep deposit of overlying unstratified gravel, clay and large boul- 
ders has been removed. One of these blocks also exhibited strize 
on the flat sides, and parallel to the longer axis, but intersected by 
