CAERNARYONSHIRE AND ANGLESEY. 303 
pendix, No. VII.) A little north of Penbryn is a quarry on road 
(to which we were directed as the ‘‘ hardest rock in these parts”) in a 
dull greenish-grey schistose rock (ude Appendix, No. VILL). This 
rock has, in parts, a peculiar brecciated or fragmental aspect, the 
fragments in one or two places becoming quite distinet by weather- 
ing and being angular. It is the sort of rock I should expect would 
be produced by the metamorphism of a rather basic volcanic ash. 
Crossing the creek we found, in a pit between the main and cross- 
road near the church (nearest to the cross-road), another schist with 
indications of included fragments and some appearance of a fault. 
In the road-cutting a few yards off the granitoid group of the 
former type appeared. We then followed the main road (running 
N.N.W. of Llanfaelog church) over a second ‘ granite’ promontory ; 
the ‘granite’ here is rather darker, having more of some green 
mineral (vide Appendix, No. IX.). It is obvious sly not true granite, 
and at times has an appearance as if it were made up of rolled 
fragments, such as we might suppose a coarse quartz-felspar grit, 
highly altered, would assume. . 
“ Towards the middle of the mass it is distinctly a porphyritic gneiss 
with pink felspar crystals. Just beyond ‘Siop’ is a shallow valley 
with stream running through it, Turned into field. On the slope 
we have pale-coloured gneissose rock, and near the bed of the valley 
a coarse purplish quartzose grit, with a well-bedded finer grit above ; 
dip 30° W.N.W., the nearest exposures of grit and gneiss being 
fifty yards apart. Walked along valley to railway, then turned back 
along it, entering a cutting. Here we find a dull bluish or greenish 
schist (vide Appendix, No. X.), overlying a porphyritic gneiss with 
pink felspar crystals (Appendix, No. X1.), like that eeentioded above. 
The gneiss begins about twenty yards from the opening of cutting, 
and there seems to be a slight fault at junction; but as there are 
eneissose bands on the one side and schistose bands on the other, it 
is clear the fault is unimportant (if it exist) and there is a true 
sequence. We walked rapidly back along the railway, passing 
mostly through granitoid gneiss, and noting the schistose band that 
separates the On granite ” promontories.”” 
The western edge of this axis seems to be a line of fault; for 
Silurian beds are brought down against it almost continuously along 
this side. Beyond the Silurian area the metamorphic rocks again 
occur, here chiefly in the character of micaceous, quartzose, and 
chloritic schists with bosses of serpentine. The beds here generally lie 
at rather low angles, and are frequently much contorted. The 
whole of these Toes are so well described, and their behaviour illus- 
trated, by Professor Ramsay in his excellent memoir“, that it seems 
quite unnecessary here to do more than refer the reader for an 
further information required to that work. It would be quite be- 
yond the scope of the present paper to attempt to describe minutely 
these rocks in the various districts in Anglesey. My wish only is 
to point out certain places where characteristic beds in each group 
may be found, The rocks in the last district referred to, as well as 
* Mem, Geol. Survey, vol. iii, 
