324 Messrs. W. Phillips and S. Woods on the | [Nov. 
the blue and purple varieties of ordinary slate. These all occur 
interstratified with the rocks above-mentioned, and certainly 
partake of their nature. The slates of the vast quarries at Nant- 
francon dip beneath these rocks towards the south east, while 
similar rocks occur at the coast on the north-west of Bangor: 
on these rocks we incline to believe the slates of Nant-francon 
actually rest ; but having had no opportunity of ascertaining the 
fact, we recommend its investigation to future observers. Of 
this, however, we are assured, that we have often perceived 
similar slates interstratified with the same rocks, and conclude 
from this and other circumstances, that the slates of that quarry 
strongly partake of the nature of chlorite slate. A Si 
One fact, and we consider it as a somewhat remarkable one, 
is, that the plane of the cleavage of the slates and slaty rocks 
runs everywhere (with the exception of one hill) from the east of 
north to the west of south, the slates being in some few instances 
vertical, but more commonly dipping at a high angle towards 
the west of north, or east of south. From this circumstance, it 
may, perhaps, be argued with much probability, that even the 
most mountainous tracts of North Wales do not present any 
appearance of that kind of disturbance, which, in some coun- 
tries, is not uncommon, and which is considered to have arisen 
from depression on the one hand, or elevation on the other. 
The slaty cleavage being, as we have already described it, it 
follows of course that no mantle-shaped masses were observed. — 
We are not disposed to view the circumstance of the almost 
uniform direction of the plane of the slaty cleavage as an isolated 
fact, relating simply to the geological structure of Wales, but as 
being probably connected with that of our island generally ; for 
it is well known that the newer strata of England possess the 
same general bearing, as may be perceived at once by casting the 
eye over a geological map of our country. When thus viewed 
in connexion with a series of numerous beds, this point appears 
to assume an interest at once both important and extensive. 
Shells occur in greater abundance, and of more varieties, than 
we expected to find. 
In North Wales, we did not perceive a single instance of con- 
tortion either in its rocks or slates. 
With the intention of ascending Snowdon by all the customary 
routes, our first station was at Capel Curig Inn, but for several 
days our hopes of making an ascent were disappointed by the 
wetness and haziness of the weather, which prevented us from 
even discerning the mountain, and ultimately deprived us of the 
opportunity of ascending it from all the various points. Mean- 
time we were induced by Mr. Dawson, who did us the favour of 
a visit at Capel Curig, to ascend and examine the neighbouring 
mountain Moel Shabod. Previously to our ascent, the gentle- 
man above named mentioned to us one circumstance which for- 
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