300 Correspondence—Dr. H. Hicks. 
than the Cambrian conglomerate of the mainland, regarded by Prof. 
Hughes as the base of the true Cambrian, and are probably older, cor- 
responding with some part of the series between it and the great masses 
of quartz-felsite which are developed near Llyn Padarn and Port 
Dinorwig, which series lithologically and stratigraphically corresponds 
with the typical Pebidian of Pembrokeshire. Hence, as the Anglesey 
schists are in the full sense of the term metamorphic rocks, and the 
‘“‘Pebidian”’ but slightly altered, this section shows that the former 
must be much older than the latter, and so be distinctly Archean. 
3. “On the Rocks between the Quartz-felsite and the Cambrian 
Series in the Neighbourhood of Bangor.’ By Prof. T. G. Bonney, 
M.A., F.R.S., Sec. G.S. 
This district has already been the subject of papers by the author 
(Q. J. G. 8S. vol. xxxiv. p. 137) and by Prof. Hughes (vol. xxxv. p. 
682), who differs from him in restricting the series between the quartz- 
felsite and Cambrian conglomerate to little more than the bastard slates 
and green breccias of Bangor mountain. The author has traced on the 
S.E. side of the Bangor-Caernarvon road a well-marked breccia con- 
taining fragments of purple slate mixed with volcanic materials below 
the above-named Bangor series for more than a mile. At a lower level 
he has traced another well-marked breccia, chiefly of volcanic materials, 
for half a mile; and, lastly, a grit and conglomerate, apparently resting 
on the quartz-felsite named above, composed of materials derived from 
it. This has been traced on both sides of the road mentioned above for 
nearly two miles. or these and for other reasons given in the paper, 
the author is of opinion that, as he formerly maintained, there is a con- 
tinuous upward succession on the 8.E. side of the road, from the 
quartz-felsite at Brithdir to the Cambrian conglomerate on Bangor 
mountain. The district on the N.W. side of the road is so faulted that 
he can come to no satisfactory conclusions. ‘he author is in favour of 
incorporating the above-named quartz-felsites with the overlying beds 
as one series, corresponding generally with the Pebidian of South 
Wales; older than the Cambrian, though probably not separated from 
it by an immense interval of time. An analysis of the Brithdir 
quartz-felsite by Mr. J. J. Teall was given, from which it appeared 
that the rock corresponds very closely with the “‘ devitrified pitchstone ”’ 
of Lea rock in the Wrekin district, described by Mr. Allport, but 
differs considerably in composition from those in the Ordovician rocks 
of North Wales. 
(C/@n=sy SaaS iS OF Npab saa ease 
eee ee 
PROF. GEIKIE’S PAPER ON THE ST. DAVIDS ROCKS. 
Sir,—As my views on the St. Davids rocks are very freely 
criticized in the abstracts published of the paper read by Prof. Geikie 
at the Geological Society, on March 21st and April 11th, I trust 
I may be allowed to state that during the discussions which followed 
the reading of the paper, I emphatically denied that the evidence 
submitted by Prof. Geikie could in the least degree affect the con- 
clusions I had arrived at. I stated also at the meeting on April 11th 
