414 Messrs. W. Phillips and S. Woods on the [Dec. 
this district is not quite vertical, and the direction of the differ- 
ently-coloured layers not quite horizontal; but they are never 
at right angles to each other ; for it uniformly appears to be the 
case, that if it were possible to divide the latter along the lines 
separating the differently-ccloured parts from each other, and 
all along the cleavage in the direction of the slate, we should 
reduce them into rhombie masses, agreeing in form with those 
often observable in slates, owing in the one ease to a species of 
natural cleavage, or in the other to the progress of decompo- 
sition. = 
A consideration of the nature of these specimens just de- 
scribed, and more especially the inspection of the masses exhi- 
biting the same effects on the large scale, amply account in our 
estimation for the appearances of stratification on the summit of 
the ridge connecting the Lluwydd with the Widdfa. It would 
account at least for the resemblance of a nearly horizontal stra- 
tification ; and from examination of the spot, we are inclined to 
believe that the appearance of the dip and rise of the seeming 
strata is to be attributed only to the actual imequalities of its 
surfaces. <A basin offering the same appearances of stratifica- 
tion occurs at the head of Llyn Idwell, in a branch of the Glyder 
Mountain, which we could not visit, but have no doubt they may 
be attributed to the same cause. 
The continuation of our walk beneath the summit of the 
Lluwydd for about a mile, and a quick descent at its termina- 
tion into Cwm Llan, offered no change in the nature of the rocks. 
The upper part of the descent of the Cwm is composed of blue 
slates, but nearthe bottom appears a long and thick ridge in the 
direction of NE and SW of the rocks so often noticed as oceur- 
ring abundantly at the base of Moel Shabod; these continue to 
the foot. The dip of the slaty cleavage on the whole of the 
descent is towards the NW at about the usual angle of 54°. The 
appearance of roundness on the summit of the rocks heretofore 
noticed is remarkable in this neighbourhood. 
Not far beneath the summit of the Lluwydd, which is 3000 
feet above the sea, is a copper mine, the principal vein, accord- 
ing to the information of an intelligent miner, runs about NE 
and SW, and is about 18 inches wide. It possesses several strings 
or leaders, on some of which they were working ; these did not 
appear to have any regular walis, and seemed to run nearly 
N and 8, and to consist of a multitude of small strings traversing 
a rock greatly resembling that already described as being 
chiefly visible among the rubbish of the Widdfa mine, and, like 
it, containing minute crystals of iron pyrites. 
In passing along the road from Capel Curig to Beddgelert, 
we perceived no rock with which we were not already ac- 
quainted ; and for about two miles north of Beddgelert towards 
Carnarvon, only the same varieties occurred. The same obser- 
