Among the Ancient Glaciers of North Wales. 9 
a finger- touch would seem sufficient to dislodge it from its precari- 
ous position. The thought involuntarily occurs, how came it there ? 
What agency could have transplanted it thither without rounding 
or breaking off a single corner, and left it where it stands, with so 
cautious and gentle a hand that it rests securely not at the edge 
but on the side of a steep and smooth incline ? It is utterly impos- 
sible that it could have rolled thither ; for if so, the momentum 
which carried it to its present position, must have precipitated it 
down the cliffs below. In all probability, any force which could have 
moved it three inches from the top of the incline on which it rests 
would have been sufficient to send it crashing down to the bottom 
of the valley. Hardly any traveller can have passed up the vale — 
from one part of which this rock forms a very conspicuous object — 
without having had some such thought presented to his mind. 
Those, however, who are aware that the existence of a great glacier 
in this valley at some remote period is a geological certainty, will be 
at no loss to recognize in this rock a remarkable and most charac- 
teristic specimen of those transported blocks whose occurrence in 
various parts of the world, at great distances from the parent for- 
mation, was 80 long a mystery to the philosophic inquirer, but 
which are now recognized as among the surest indications of glacial 
action. 
Climbing now from the high road to the block I have been de- 
scribing, we perceive that it is only one — although much the larger — 
of a great number of similar blocks, which are deposited in the same 
manner on the sides and at the edges of the sloping or precipitous 
faces of rock which flank the northern side of the Vale of Llanber- 
ris. The greater part of these extend in a well-marked and toler- 
ably regular line, and at elevations varying from 300 to 500 feet 
above the course of the stream, for perhaps a mile further down 
the valley — until, in fact, its sides become too steep and precipitous 
to admit of such deposits being made. Clambering along this side 
of the valley, we examine the faces of the rock around and beneath 
these blocks, and find many of them— especially such as have not 
been exposed to the action of the water-courses which trickle down 
here and there into the stream below — deeply scored with the char- 
acteristic striae of glacial action. If we now cross to the opposite or 
southern side of the valley (the flank which lies beneath Snowdon), 
we shall find all the indications of glacial force — the deep notchings 
of the striae, the polished and rounded surfaces which continental 
geologists term rochers moutonnes, and the transported blocks poised 
