THE GLACIAL DEPOSITS OF NORTHERN PEMBROKESHIRE. 1) 
Symonps, in his book entitled Records of the Rocks (p. 53), refers to the fact 
that the country near St David’s must in former years have been largely covered by 
boulders. These have now to a large extent been cleared away from the surface and 
used for building rough walls which serve the purposes of fences and hedges. He adds 
that in his opinion “ these boulders are all local, and have travelled over a slope of 
ice and snow which once reached from the Trap Hills of Precelly down to the sea.” 
And in another place (p. 181) he speaks of the Precelly hills in North Pembrokeshire 
as being “studded with ice-carried boulders, which were used for cromlechs and tumuli 
by a prehistoric race of men.” 
Messrs Howarp and Smatt, in their “Geological Notes on Skomer Island,” which 
appeared in the Trans. Cardiff Naturalists’ Soc. (vol. xxviil., 1896), assert that distinct 
evidences of the action of ice are seen on the mainland opposite Skomer. And on 
Skomer Island itself blocks are found which have travelled from the St David’s district 
and some possibly from North Wales. Flints were also seen scattered about. 
Professor M‘Kenny Hucuss, in his paper “On the Drifts of the Vale of Clwyd” 
(Quart. Journ. Geol. Soc., vol. xliii., 1887), remarks that “the low-lying plateau at St 
David’s is covered by a gravel containing flints.” But he found no traces of shells there. 
In a paper by Professor Bonney ‘On the So-called Diorite of Little Knott 
(Cumberland), with further Remarks on the Occurrence of Picrite in Wales” (Quart. 
Journ. Geol. Soc., vol. xli., 1885), some observations are found communicated by Dr 
Hicks relating to the glaciation of the St David’s region. <A boulder of picrite was 
found on the promontory just to the east of Porth-lisky, ‘“‘ resting immediately on 
Dimetian rock, surrounded by an uncultivated area overgrown by gorse and heather.” 
The striz along the coast are said to run usually from north-west to south-east. He 
adds : “‘ But it is clear that very many of the boulders scattered over it must have come 
from the high land in the north-east of Pembrokeshire, the Precelly range. There is 
ample evidence of local till, and in places (at considerable elevations) of marine sand 
with transported boulders, fragments of flint being common among them.” Dr Hicks 
was of opinion that “this points to the derivation of some of the materials, including 
possibly certain boulders, from a north-west source.” 
The most important communication which has appeared on this subject is a very 
short report read by Dr Hicks at the Cardiff meeting of the British Association in 1891, 
“On the Evidences of Glacial Action in Pembrokeshire, and the Direction of Ice-Flow.” 
This report is reproduced in the Geol. Mag. for that year. He there refers to the 
presence of ice-scratched rocks and of northern erratics in the district. The direction 
of the glacial strize and the probable presence of erratics from North Wales and from 
Ireland “would tend to the conclusion that glaciers from these areas coalesced in 
St George’s Channel, and that the ice which overspread Pembrokeshire was derived 
from both these sources, as well, probably, as from a flow extending down the Channel 
from more northern areas.” By far the majority of the boulders are said to be of local 
origin, but he notes a large boulder of granite and another of picrite found on Porth- 
