440 THE JASPERS OF SOUTH-EASTERN ANGLESEY. [ Aug. 1902, 
being deposited; and partly to the effects of the intense crust-creep — 
to which the area itself had afterwards been subjected. Consider, | 
for example, such an area as originally forming part of a slightly 
submerged continental shelf, or coastal platform, with volcanic and 
archipelagic conditions, and overlooking (say) to the south-eastward 
a broad and deeper sea. Suppose, further, the platform itself floored 
by rocks already metamorphosed, and that this platform remains 
covered by shallow waters for an extended period of geological 
time, while the sea-floor in front of it is continually deepening. 
Under these conditions, only such mechanical, volcanic, or organic 
material could become accumulated as rock-layers on the submerged 
platform, as by their original nature or rapid cementation were 
incapable of being swept off by the waves and currents of the 
shallow waters into the open and deepening sea beyond. Such 
rock-formations as would be accumulated on the platform would 
necessarily be thin, but would be iithologically varied and peculiar; 
while those laid down in the deepening sea outside would be of 
relatively enormous thickness, but would be lithologically mono- 
tonous, If, later on, the two regions became intensely folded, 
compacted, and overthrust by crust-creep, and the crests of some of 
the fold-ridges on the platform were worn down by denudation, so 
as to expose their cores formed of the original basement-floor ot 
metamorphic rocks, most of the puzzling field-phenomena presented 
by Anglesey and North Wales, and the peculiar areas of similar 
character found elsewhere, might be expected to follow as a natural 
consequence, 
The Avuruor felt that, at that late hour, it was impossible to reply 
to the interesting points that had been raised in the discussion. 
He did not, of course, claim, in the absence of recognizable radiolaria, 
to have made a true demonstration of the organic origin of these 
jaspers ; but he did submit that three converging lines of indirect 
evidence established a very strong probability. He laid especial 
stress upon the fine clastic nature of the jaspery phyllites. With 
regard to the relations of the jasper-bearing group to the crystalline 
schists, nothing that he could then add would better illustrate the 
peculiar perplexities of this problem than the remarks of Dr. Flett 
upon the rocks of the Highland Border. The interest that had 
been evinced by the Fellows of the Society would be a great en- 
couragement in the work that still lay before him in the remaining 
parts of the island. He wished, in conclusion, to draw attention to 
the photographic reproductions by the process of contact, for which 
he was indebted to the kindness of Mr. J. H. Player, F.G.S. 
