322 Dr. CO. Callaway—The Archean Controversy. 
The rhyolites near Llyn Padarn and the felsitic and schistose masses 
of Lleyn district are also claimed as Archean by Dr. Hicks, and 
Prof. Bonney admits the claim so far as Llyn Padarn is concerned. 
Mr. Tawney and Mr. Harker have, however, maintained that some 
of the igneous masses in the Lleyn area are intrusive in the 
Ordovician strata This may well be the case; but I am convinced 
that the quartz-felsites south of Bangor and on Llyn Padarn are 
truly Archean. The massive conglomerate running from Llyn 
Padarn to the south-west along the crests of Moel Tryfaen and 
Mynydd y Cilgwym is packed with rounded fragments of the 
subjacent felsite, while the Cambrian grits further west are largely 
composed of similar material, which also occurs in smaller proportion 
in the Cambrians near Harlech. 
Ancursrty.—Prof. Sedgwick was amongst the first to express the 
opinion that this island contained rocks older than the Cambrian. 
In our own times, Dr. Hicks, fresh from his discoveries in South 
Wales, visited the area, and rapidly concluded that his three systems 
were represented respectively by the granite (Dimetian), the halle- 
flinta (Arvonian), and the schists (Pebidian). Prof. Bonney and 
Prof. Hughes, approaching the study of the rocks from different 
sides, agreed that the island contained extensive tracts of Archean 
rock ; but they did not venture upon detailed conclusions. My own 
work in Anglesey extended over several years, and led me to believe 
that the crystalline and hypo-crystalline rocks were mainly Archean, 
but that they could not be grouped into more than two distinct 
systems, Older Archean (gneissic) and Newer Archean (slaty). 
The latter I did not attempt to subdivide into a definite succession. 
The former appeared to display a sequence of the following groups, 
taking them in ascending order :—(1) Halleflinta, (2) Quartz-schist, 
(3) Limestone, (4) Grey gneiss, (5) Dark schist, (6) Granitoidite. 
Thus the case stood as the result of work upon the old lines. 
My enquiries in Ireland and at Malvern led me in the direction 
of dynamic metamorphism, and, in the light of the new ideas, I 
re-examined the most important of my Anglesey sections. I found 
that some of the green schists were modified diorites, that the grey 
eneiss and associated schists were modified felsite, and that the 
limestones of the Older Archzeans were probably endogenous segre- 
gations. These results I communicated to the British Association 1 
in 1887. On the same occasion, Prof. J. F. Blake? reported that 
some of the igneous rocks of the island “put on a foliated character 
in places.” I followed up my clues in the following year, and 
obtained confirmatory evidence of my previous conclusions. I also 
ascertained that the halleflinta of Llanfaelog was transitional between 
felsite and gneiss, and that the granite was a truly igneous and in- 
trusive rock, associated with and apparently passing into quartz- 
felsites which were quite distinct from the above-named felsite. My 
original reading of the Newer Archzeans did not require modification. 
They were sedimentaries which had been more or less metamor- 
phosed. These results were made known® to the British Association 
in 1888. 
! Report, p. 760. 2 Ibid, p. 281, 8 Report, p. 604. 
