S38 ON THE GEOLOGY AND STATISTICS 
In no other part of this side of the Mcnai basin are the 
secondary rocks observed, except hning the eastern shore 
of the Menai Strait, between Bangor and Carnarvon. In 
this direction they occupy but a narrow space, not exceed- 
ing a quarter of a mile in breadth. They overlie the transi- 
tion rocks, and have their dip to the south-west, at a less 
angle than 45° with the horizon. 
Among these secondary rocks all the varieties of sand- 
stone may be seen. The old red is the lowest, and in con- 
tact with transition slaty rock; and between it and the 
new red sandstone, the other series of sandstone, mountain 
limestone, and the coal measures. An interesting section 
of all these rocks, for the geologist, is offered in the quarry 
that was opened for materials to construct the masonry of 
the Menai iron-bridge. This quarry is about a mile to the 
north of that bridge, and is contiguous to the Menai Strait. 
The whole of the Snowdon chain may be said to abound 
in the metals, but, as we found to be the case with work- 
able slate, their quantities are greatest in those parts of this 
range where the rocks are hardest, and least given to de- 
composition. 
Of all the metals met with in these mountains, copper is 
the most abundant. The richest mine of this metal is in 
Snowdon mountain, which is traversed from south to west 
by several traceable copper-veins ; but only two of them 
are worked ; though in several other places, as to south- 
west of Penmaen Bach, on the banks of the Ogwen at 
Coitmore, in a ravine between the Bethgelert road and 
Nantle lake, it is found, but in smaller quantities, and in 
less purity, than that of Snowdon. 
In the mountain of Snowdon, we have just mentioned 
that two different veins of copper are now wrought. The 
richest metal is that which is got in the vein situate near 
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