g6 proceedings of the geological society. [May 1894, 



Needles of Howth,in pinkish- coloured beds of sandstone, innumerable 

 small worm-tubes, about ^ inch in diameter, occur running trans- 

 versely to the planes of bedding, and these seem equally to recall 

 the ' small pipes ' which occur on the lowest annelid-horizon of 

 Sutherland. We must not forget, however, that worm-casts have 

 been noticed in the upper beds of the Torridon Sandstone. 



Crossing St. George's Channel, we find ourselves in Anglesey, a 

 land of pre-Cambrian mysteries, which I scarce venture even to 

 glance upon. The older rocks of the island have been described 

 with the most careful detail by Prof. Blake in his comprehensive 

 paper on the Monian System ; but since that author's conclusions 

 have already been discussed in a previous Presidential Address, it 

 would seem like a work of supererogation to dwell on this topic at 

 any length on the present occasion. It will be remembered Prof. 

 Blake desired to show that the whole of the rocks which, under 

 various names, had been described as pre-Cambrian constitute a single 

 well-characterized system, of which the various divisions hitherto 

 described are integral and inseparable parts. These rocks are found 

 in six districts of Anglesey. The Lower Monian is represented by 

 grey gneiss and mica-schists, quartzites, chloritoid and chloritic 

 schists ; the Middle Monian is represented by a volcanic facies and by 

 a slaty facies. The South Stack series also belongs here, but in the 

 map showing the distribution of the Monian rocks in Anglesey no part 

 is assigned to the Upper Monian, although it would appear that the 

 Howth Hill and Bray Head rocks, previously mentioned, are regarded 

 as possibly Upper Monian. Of course it is well known that the authors 

 and originators of the other pre-Cambrian systems do not look with 

 favour upon the Monian system, which, like Aaron's rod, seemed 

 likely to swallow up the rods of the other magicians. Into this 

 controversy I must not enter, the more so as it would involve the 

 consideration of points already discussed by Sir Archibald Geikie. 

 It is enough to indicate that the Director-General of the Geological 

 Survey has still more recently given his opinion that the coarse 

 gneisses of Anglesey present some striking external or scenic resem- 

 blance to portions of the Lewisian rocks, whilst the schists, quartz- 

 ites, and limestones of that island present a close resemblance to the 

 Dalradian of Scotland and Ireland ; the quartzites, like those of the 

 Highlands, containing worm-burrows. * Dr. Hicks still more 

 recently quotes these opinions as practically endorsing his own 

 views: names apart, where Sir Archibald sees Dalradian, he mainly 



1 ' Journal of Geology,' vol. i. pp. 12, 13. 



