82 GLACIAL ACTION AMONG BRITISH MOUNTAINS. 
April, 1891 . 
slopes of the mountain, with here and there large grooves 
running along in the direction the ice must have taken in 
being forced by its weight above, through this narrow passage, 
and poured into the valley below. The features at this spot 
are most clear, and the height considerable to which you may 
see the ice must have reached. 
In the glen just above now extends the narrow but deep 
rock-bound lake of Llyn Orthin. After noting these indica¬ 
tions, I was pleased one day to find below, in the more open 
valley to which Cwm Orthin leads, a well-marked striated 
rock specimen, which I have brought and placed on the table 
with a few other glaciated stones. I found it near the site of 
the present railway station of Blaenau Ffestiniog, at a depth 
of several feet, where channels had then been recently cut 
deep into the previously undisturbed bed of the valley, and 
below a thin layer of peat. 
Again, when once spending a short holiday at Llanbedr, I 
found clear and very telling phenomena of the agency of glaciers 
up in the higher portion of the valley of the little River Artro, 
near to the rugged and wild mountains on each side the ancient 
Pass of Drws Ardudwy. There I found one particularly 
interesting large rock surface, bare of vegetation for a con¬ 
siderable space, and wearing still an aspect of surface planed 
off, largely smoothened and grooved. Down below this, not far 
away, where the valley is wide and flat, I noticed many blocks 
that seem impossible to have been carried where they are by any 
other action but ice, which has (it seems to me) let down one 
unusually large mass on to a bare surface of rock. In search¬ 
ing below among small stones I met with some distinctly stri¬ 
ated, although apparently they could not have travelled far. 
Once in walking down the narrow Pass of Drws-y-Coed, 
not far from Snowdon, a wild spot, I was fortunate to 
come across a surface of the original rock (if one may use 
such a term;, just then recently laid bare in widening the 
road. It was beautifully planed over and striated in a direc¬ 
tion down the Pass. 
One sunny day of a knapsack holiday I came across a 
large block of rock in the bed of the rapid and picturesque 
Wye, near Newbridge, when walking in the bed of the stream 
where it flows wide and shallow over rocks, the water being 
then very low. It had the same appearance of rounded 
surfaces and striations on some parts, and I felt no doubt it 
had been brought out of some far recess of the mountains. 
It looked too large to have been rolled far bv the river. And 
here I would remark that this effect of ice action in 
smoothening rock surfaces causes them to be afterwards less 
rapidly degraded by ordinary weather action, as leaving fewer 
projections and angles for rain, frost, or sun to act upon. 
