218 Rev. J. F. Blahe — The Llanheris TTnconformity. 



italicized as containing the gist of the matter, that this line is the 

 line of strike of the purple slates. Is it necessary to explain that 

 if these surface beds are bands in the slate series, and we go along 

 the line of strike, we must continue on the same bed, and not change 

 again and again ? The definite succession is fatal to the hypothesis. 

 It indicates a strike at right angles to the dominant strike of the 

 district, which is only possible in superficial deposits. Even a fault 

 cannot do mucli towards altering the strike, unless it be on a 

 geotectonic scale. 



The dips Miss Raisin records in some part of these grounds are of 

 no consequence from this point of view, though combined they give 

 a general "gentle dip towards the E.N. E.," and separately they indicate 

 a slight synclinal arrangement. But in the centre of the grounds, 

 standing with one's back to the road and looking along the strike of 

 the slates of the country as shown in the neighbouring quarry, 

 we see the crag shown in Fig. 3. It illustrates at the same time the 



Fig. 3. — Low crag in the Glyn Padarn grounds, looking "W.S.W. 



perpendicularity of the strike of the beds (whatever be their dip) to 

 that of the slates, and my description of the alternations of trans- 

 versely cleaved grey slate and coarse grit characteristic of the Post- 

 Llanberis group. As noted above, a fault between this and the 

 quarry would make little difference to the argument, but of such 

 a fault there is absolutely no evidence, and in the absence of one the 

 bottom beds of worked slate in the quarry, if continued on their 

 rise, would run into this crag, or very near it. The transverse fault 

 seen in the quarry has nothing to do with this, but lies beyond. 



In the large exposed surface of conglomerate " beyond the wall " 

 a band of purple slate most certainly lies with a very low dip upon 





Fig. 4. — Mass of purple slate mud, overlying conglomerate outside the Glyn Padarn 

 grounds, looking N.E. 



it. This band is perhaps more probably a redeposited purple mud 

 than a fragment. It is shown in Fig. 4. The conglomerate, joace 

 Miss Raisin, does contain felsite pebbles, and in no way resembles 

 the St. Ann's grit, or any grit interbanded with purple slate 



