220 
ON THE GEOLOGY OF THE 
cavations have been carrying on here. And a race of men 
has sprung up, following the occupation of mining, from 
father to son, for many generations. 
The lead- veins are found in the slaty mountain rocks. 
The matrix of the ore is a quartzy calcareous spar. 
The pits are numerous and shallow, seldom more than 
twelve feet below the surface. The veins run east and 
west, and are crossed by others from north to south ; they 
have scarcely any dip, running nearly horizontal, but rise 
a little as they enter the hill to the east and south. The 
breadth of the vein is narrow, seldom exceeding eighteen 
inches. 
Calamine is also found here, but not in similar quantity 
to the lead. When it is separated from its extraneous 
matters, it is exported solely to Bristol. 
In the limestone, on the south-west side of the great 
Orme's Head, copper is found in considerable abundance, 
principally the malachite, or green carbonate of copper. 
It is found in the limestone strata, between beds of coarse 
yellowish sandstone. The shafts penetrate to a consider- 
able depth. Many hundred tons are every year raised. 
After the extraneous matters have been separated, by 
breaking the ore into small pieces, and washing away other 
impurities, it is put into bags, and sent away to Swansea ; 
and there, from the abundance of coal, is smelted, and pre- 
pared for useful purposes. 
Though there be no coal, peat is found in several places, 
but in no considerable quantity, except in the great marsh 
formed at Trefriew, on the banks of the Conway, where is 
an abundant formation of it. The nature of the rocks of 
the mountains, their steep declivities, and the drainage of 
those parts of them fitted either for pasture or tillage, ad- 
of little space for the accumulation of this vegetable 
production. The margins of the mountain lakes, generally 
