438 | MR. EDWARD GREENLY ON THE [Aug. 1902, 
Discussion, 
Mr. G. Barrow said that he was interested in the group of rocks 
described by the Author, as they were the same group as the sup- 
posed Silurian rocks along the Border of the Southern Highlands. 
They here occurred in two different ways. First, along the least 
crystalline margin of the Anglesey schists; and again, faulted in 
some way against a highly crystalline portion of these schists. The 
second area showed that the condition of the jaspers, etc. remained 
the same in both areas, and it was not credible that the pillowy 
lavas and variolites could be of the same age as the hornblende- 
schists and hornblende-gneisses comparatively close by. Still more 
important, however, was the fact that small fragments of the well- 
crystallized schist occurred in the ashy grits associated with the 
lavas. It did not seem reasonable to suppose that these grits were 
of a totally different age from the lavas, and it seemed clear that the 
Anglesey schists were crystallized before the grits, lavas, and jaspers 
were formed. 
The other (Beaumaris) area was of importance, as showing that 
on the outer edge of the aureole of crystallization in Anglesey 
these jaspers and green rocks again occur, in a manner suggesting 
their original association with the older rocks that pass into well- 
crystallized schists. But in all cases here, the junction of the 
jasper with the adjacent rock can be clearly seen to be due to 
movement, and not an original one. The evidence already given, 
however, shows unmistakably that the apparent identity in age has 
been produced by these movements, and, as in the Forfarshire area, 
it 1s a deception. ‘The evidence from Anglesey certainly suggests 
that these jaspers and green rocks may be older than the speaker 
had supposed. 
Prof. Bonnny said that he agreed with the previous speaker in 
thinking that the apparent passage from the holocrystalline schists 
into the schistose rocks was more probably due to the crushing of a 
holocrystalline and a sedimentary group near their junction. Also, 
he did not see why a radiolarian chert should be associated over 
any wide area with a peculiar form of basic lava, having a structure 
which was likely to occur towards the outside of a mass of lava. 
Though doubtful about some details, he fully appreciated the value 
of the paper. 
The Rev. J. F. Brake said that he was glad that the Author had 
visited the district near Newhorough, which, though so inaccessible, 
was the most interesting in all Anglesey to a geologist. The 
present paper, however, dealt with only a few of the points 
of interest. Although the description of jaspers and pillowy 
lavas was taken from Malldraeth Marsh, the arguments for their 
age was taken from Pentraeth, where the ground was so broken that 
the relations of neighbouring rocks were by no means clear. He 
doubted whether the material filling the interstices of the pillowy 
lavas, or the folia in the crystalline schists which had been 
exhibited, had the same origin as true nodular jaspers, such as did 
