62 DR T. J. JEHU ON 
smooth rock-surfaces, and this is partly owing to the fact that so much of the 
country is covered by the superficial accumulations; and the igneous rocks which 
project above the surface are so weathered and worn from exposure for such a great 
length of time, that any marks of glaciation which they may once have shown must 
have become almost entirely obliterated. 
Reference has already been made to Dr Hicks’ observations on the strize seen on the 
rock-surfaces at places along the coast near St David’s. The best example noted by the 
present writer is at Whitesand Bay, just at the northern corner. Here the rock, as it 
appears from under the cliff of drift, presents a distinetly hummocky appearance, and is 
smooth, polished, and well striated—the strize having a course from north-west to south- 
east. It is interesting to note that out of the drift above, striated stones can be readily 
picked : these are generally sub-angular, with blunted angles and somewhat smooth 
and rounded edges. Inthe small valley coming down near Porth Melgan, and separating 
the rocks of St David’s Head from Carn Llidi, a pavement of sedimentary rocks has been 
exposed by the removal of some turf, and this pavement shows distinct marks of 
glaciation. Another very good example of a glaciated rock-surface is seen quite at the 
other end of the district at Gwhbert, on the coast to the north of Cardigan. Here, 
emerging from beneath the drift again, a smooth and striated rock is seen—the direc- 
tion of the strize being from a little west of north to a little east of south, showing that 
the ice must have come on to the land from the region of Cardigan Bay. 
The igneous rocks of St David’s Head and those lying further east, especially at Pen 
Berry, appear to be somewhat moutonné on their northern aspect, but no unmistakable 
glacial strize were seen, and this is no doubt due to the fact that the rock-faces are so 
much weathered. 
On the greater heights there is a general absence of perched blocks and big erratics. 
It is quite possible that perched blocks may have been common in former times, but 
they have in all probability been removed by man, for the region is full of traces of 
defences prepared by primitive man, and these usually take the form of great collections 
of boulders and stones gathered together and heaped up in the form of dykes. Splendid 
examples of such ancient entrenchments are seen near St David’s Head, and again on 
Strumble Head. The few blocks seen on the high ridges are almost invariably of the 
same nature as the underlying and surrounding rocks. 
South-west of St David’s, in the Treginnis tract, some huge boulders are seen. A 
big one lies on the hill above the cliffs at Penmaen-melyn, but it consists of a somewhat 
coarse andesitic rock, which is found in situ at no great distance away. The boulders of 
granite and of picrite found near Porth-lisky farm by Dr Hicks have been already 
mentioned. ‘The whole country was once strewn with boulders ; and although many 
still remain scattered over the land, most have been cleared away and used for building 
dykes, etc. An examination of the stones in the dykes shows that they are almost 
entirely of rocks found in the locality, as might be expected. Boulders of the St 
David’s Head gabbro are found carried in a south-eastern direction, and are plentiful in 
