236 ON THE GEOLOGY AND STATISTICS 
north side of Nantle and Llanlyfne lakes. From the latter 
place an iron-railway has just been completed, nine miles 
in length, to connect these quarries with the port of Car- 
narvon. The colour of these slates is reddish, and they 
are not equal in quality to those of Dolawen and Alt Dhu. 
The veins of slate being entered from the surface, and sunk 
into a great depth, considerable more expense in machinery 
is necessarily incurred in draining and freeing the work- 
ings of rubbish in these quarries, than in the two first de- 
scribed. 
Before passing to the consideration of the other minerals 
of this side of the Menai basin, it may not be uninteresting 
to remark, that no less a quantity than 200,000 tons of 
slate is annually shipped from the above described quarries. 
And when to this we add their value, not much less than 
<£^400,000 a-year being paid for them, thus enriching the 
proprietor, and affording, at the same time, a comfortable 
livelihood to a population of 20,000 people, including wives 
and children, some idea may be formed of the immense im- 
portance of slate to the county of Carnarvon*. 
The other transition-rocks which are found in this por- 
tion of the Menai basin, are more curious than valuable. 
Around the eastern and northern faces of Snowdon, as seen 
from the pass of Llanberris, hornblende, porphyry, basalt, 
* We cannot here refrain from observing, that these quarrymen, though 
civil and industrious, do not possess the same information and intelli- 
gence that the miners of Leadhills and of Wanlockhead, in Scotland, 
have. While the latter have extensive libraries to instruct them, the 
slate quarrjmen and miners of North Wales are entirely without these 
valuable sources of mental improvement. It may be remarked, that 
the miners of Leadhills have a library of 1200 volumes; and tliose of 
Wanlockhead, another of 700 volumes. All which books are more tho- 
roughly read, and more anxiously sought after by the industrious 
miner, than the numerous and splendid collections in many of the li- 
braries in the low country ; hence these people are comparatively well 
informed. 
