ON A NEW GROUP OF PRE-CAMBRIAN ROCKS IN PEMBROKESHIRE. 285 
23. On a new Group of Pre-Camprian Rocks (the ARVONTAN) in 
PrmBRoKESHIRE. By Henry Hicks, M.D., F.G.8. With an 
Apprnpix, by T. Daviss, Esq., F.G.S. (Read February 5, 1879.) 
= 
Durtné my researches in Pembrokeshire last year, I was fortunate 
enough to discover some new areas of Pre-Cambrian rocks, and, 
moreover, to make out that the rocks which chiefly occupied those 
areas were generally unlike those which I had previously described 
under the names Dimetian and Pebidian. 
Indeed it soon became evident that the majority were of a kind such 
as had not previously been recognized, at least to any extent, in the 
eae ea 
i Fig. 1.— Sketch Map of St. David’s Head and the neighbouring parts 
) of Pembrokeshire. (Scale about 6 miles to 1 inch.) 
HEE Curboniferous 
Silurian 
(UA Cambrvary Str 
I == Pebidian ( | Tl 
i = ees TA 
pian | co. 
tntrusweliochs & Faults net urvdecated, 
gil 
al 
ell Patil 
| | 
— 
—SS 
SS ] 
——— 
im i | 
i val: " | 
oc 
RAMSEY I? 
moe Ror DE Ss 
SKOMER I° 
