522 H. HICKS ON THE PRE-CAMBRIAN 
metamorphism, in the sense in which that term is generally used, 
of the individual fragments which build up the rocks. 
The rocks No. 3 on the map (Pl. XXIV.), which succeed the last 
mentioned, are red slates and shales, not of great thickness, but in- 
teresting as containing the earliest fauna found in this neighbourhood 
(probably the earliest of the types as yet found anywhere), and they 
form also a well-defined horizon throughout the district. These are 
succeeded by the thick beds of grits and sandstones (No. 4), usually 
purplish or greenish in colour, found on the shores on each side of 
Caerbwdy Creek. They are the rocks which have been'quarried for the 
restoration of the cathedral. Microscopically they do not differ much 
from the green sandstones (No. 2), but they more frequently contain 
large fragments, and well-rolled bits of typical Dimetian may be 
readily discovered in some of these beds. The best spots, however, 
for collecting the typical fragments will be referred to in speaking 
of the Nun’s Chapel area; but I have found numerous fragments in 
the grits of this area also, especially immediately to the south of the 
village called Trelerwr, which is on the strike of these beds. The 
next series (No. 5) is a thick one, and consists of alternations of flaggy 
sandstones, grey and greenish flags, and purple and red flags, slates, 
and grits. The lower beds contain a tolerably rich fauna, with 
the genera Plutonia, Paradoxides, Conocoryphe, &c. A part of this 
series, and also of the underlying one, has been dropped by a fault 
which cuts across the beds, as seen on the map (Pl. XXIV.), in a 
direction from N.E. to $8.W. Continuing along the section further 
to the 8.E., the Menevian beds (No. 6) are found resting conformably 
upon the upper beds of the last-mentioned series; and the Mene- 
vian beds are succeeded still further to the $.E., beyond the well- 
known creek of Porth-y-rhaw (where the Menevian beds were first 
explored, and most of the fossils obtained), by the Lingula Flags. In 
consequence of the repetitions of these last beds by frequent foldings, 
no higher beds than those belonging to the Lingula-Flag group are 
found along the coast between this point and the ridge of Pre- 
Cambrian rocks below Pointz Castle on the west shore near Newgale 
Sands. More inland, higher beds are found in the centre of the 
trough, which is bounded on the one side by the St. David’s Pre- 
Cambrian ridge and on the other by the Brawdy and Hayscastle 
ridge. 
c. Faults and thew Effects—These areas are at many points 
greatly traversed by faults, and any one who has a difficulty in 
believing that the faults indicated on the map (Pl. XXIV.) are not 
exaggerated in their number and extent, would do well to examine 
some parts of these districts where fossiliferous beds occur. For 
instance, the valley of Porth-y-rhaw, from Nine Wells to the coast, a 
distance only of about halfa mile, would, I believe, more than convince 
any one who examined it that instead of faults being indicated on 
the map in too great a number, there are far fewer shown than can 
be actually traced. The same beds are repeated several times by 
faults in this valley, as proved by the rocks and fossils, and the 
Lingula Flags of the coast to the S.E. are actually thrown back 
