538 H. HICKS ON THE PRE-CAMBRIAN 
reposed almost directly on the Dimetian until disturbed by the 
faults. The presence of a great amount of arkose material in the 
conglomerates, and the fact that at this point a brecciated mass 
was found resting upon and sticking to the Dimetian, and consisting 
almost entirely of fragments of the Dimetian, lends some weight to 
this supposition. I do not feel quite justified, however, in claiming 
this breccia as a part of the true Cambrian conglomerates; but 
the examination of it with the microscope (Note 42) seems adverse 
to its being only brecciation of the Dimetian zm situ as the result of 
the fault or crush. In any case, as there may be a possibility of 
doubt, I prefer to depend, for the evidence of Dimetian fragments 
occurring in the conglomerates, on those found in the beds already 
referred to, and in others which strike up against the Dimetian near 
here. The Dimetian between this point and the Allan Valley is 
defined by a sharp line, and the Cambrian beds all along strike up 
against it. According to the Director-General’s view they have been 
actually cut or eaten through by the Dimetian. There is not a 
particle of evidence for this, but there are facts in abundance to show 
that the line of -junction is a sharply-defined fault, and in the more 
gritty bands of these Cambrian beds fragments of Dimetian occur 
plentifully, even close to the point where the Dimetian is supposed 
to be eating through them. 
Returning to the coast at and to the south of Ogof-llesugn we come 
to the place described by the Director-General as follows (p. 277):— 
‘*Qn the seaward face of the cliff the granite has torn off a mass 
of conglomerate ard associated tuffs. These rocks have been so 
intensely indurated and silicified that the quartz pebbles are hardly 
traceable on a fresh fracture, though they project more evidently from 
a weathered surface. It is even difficult in places to say precisely 
where the line between granite and conglomerate should he drawn, 
so intimately are they welded together.” I have endeayoured to 
show in the sketch, fig. 11, the real conditions exhibited here. The 
conglomerate is undoubtedly a part of the lower Cambrian conglo- 
merate, and with it are some beds which belong to the next series, 
the green rocks. The mass appears to be surrounded on two sides, 
not by Dimetian, as stated by the Director-General, but by dykes of 
diabase containing lenticular fragments torn off from the Dimetian. 
The Cambrian conglomerate does not appear to have been much, if 
at all, altered by the dykes, and on the cliff side there is an open 
space at some points a few inches across, between the conglomerate 
and the dyke. Along the northern edge, especially, where the con- 
glomerate mass narrows, it seemed almost to stick on to the dyke ; 
but there is no evidence here that it was actually penetrated by the 
dyke. .The fine sandstone in association with the conglomerate is 
described by Mr. Davies in Note 64. As this seemed in the field to 
show some indications of having been altered by the dyke, I had it 
cut; but the microscopical examination does not support the view 
of any great amount of alteration. The idea that this mass of 
conglomerate is entangled by the Dimetian disappears instantly on 
examination, and the conditions exhibited are those due to crushings 
