ROCKS OF PEMBROKESHIRE. aon 
has caused the errors to be committed here as in the other areas 
referred to. Moreover, Dr. Geikie’s statements tend to show that 
the examination here of the actual facts must have been im- 
perfectly carried out; for the most important point of contact of 
the Cambrian with the Dimetian, shown in fig. 10, is not even 
referred to. 
Fig. 10.—Section showing contact of Cambrian with Dimetian in 
Cliff at Ogof-llesugn. 
Dimetian. 
Diabase dyke. F. Cave. Cambrian. 
When the Director-General read his paper, even minor faults were 
condemned by him. In a footnote, inserted after the discussion, it 
is stated, however (p. 277), that “ possibly some slight displacement 
may have taken place at Ogof-llesugn; but the mass of con- 
glomerates is imbedded in the granite.” This does not very much 
improve the statement in the text on the same page that the 
“granite which extends continuously eastward from Porth-lisky, 
abruptly ends off and is succeeded at once by vertical sandstones and 
shales which are truncated by it nearly at a right angle.” The 
point where the conglomerates and sandstones touch the Dimetian, 
and, according to the Director-General, are truncated by it, is shown 
in fig. 10, and I believe that those who have examined the spot, and 
they are now many, will admit that this sketch gives a fair repre- 
sentation of the conditions to be seen. It shows the Dimetian to be 
sharply defined, with some beds of the Cambrian conglomerate lying 
against it.° The line of fault is clearly indicated by fault-breccia 
above and by a narrow cavern below, into which some of the younger 
members of Prof. Hughes’s party were able to squeeze themselves 
for several yards. As much higher beds of the Cambrian series 
than these are found, directly to the north, to strike up against the 
Dimetian, it is clear that these beds are bounded at Ogof-llesugn 
by two faults, as shown on the map (Pl. XXIV.). These probably 
are some of the lowest Cambrian conglomerates, and they may have 
