THE GLACIAL DEPOSITS OF NORTHERN PEMBROKESHIRE. CE 
found to be very similar to underlying grit rock when this is broken up. So it 
may represent material ground out of the solid rock by the movement of land-ice. 
Further inland a good example of the Upper Drift is seen in a cutting on the roadside 
between Puncheston village and the railway station. It is a stony and rather rubbly clay. 
Close at hand, on Puncheston common, the Lower Boulder-Clay crops to the surface. 
Further east, up to Cardigan, the Upper Boulder-Clay and Rubbly-Drift are seen 
in many places overlying sands and gravels or lying immediately on the blue clay. 
The line of division between this Upper Boulder-Clay and the sands and gravels 
is not so marked as that between the sands and gravels and the Lower Boulder-Clay. 
Scole 40Ffr to lin. 
Fic. 3.—Section at Boring No. 1 on Goodwick to Letterston (existing) Railway, 
between Tregroes Moor and Manorowen. 
V. Tue Bounpers AND ERRATICS. 
The transport of boulders is of great importance as indicating the general direction 
of ice-movement. Throughout northern Pembrokeshire boulders may be seen scattered 
over the surface, and are especially common on waste or uncultivated land. Many of 
those found on the slopes of the hills have no doubt rolled from the parent rock above, 
but many, though not foreign to the district, have yet been carried for some distance by ice. 
Where the land is cultivated an immense number of boulders must have been 
removed, but even in the fields it is common to meet with big blocks of igneous rocks, 
which, as a rule, have been left in the position where they were originally stranded 
in order that cattle may have something to rub against, or have been left on account 
TRANS. ROY. SOC. EDIN., VOL. XLI. PART I. (NO. 4). 13 
