THE GLACIAL DEPOSITS OF NORTHERN PEMBROKESHIRE. 81 
on the beaches. 
from rocks hidden under the Irish Sea. 
These also must be derived from the north-east of Ireland and 
From the cliff of Upper Boulder-Clay at Porth-lisky a boulder of olivine-dolerite 
was obtained, microscopic sections of which show very fresh olivine. 
It is certainly 
a Tertiary rock, and has probably come either from the north-east of Ireland or from 
the western isles of Scotland. 
3. Erratics found on the shores along the coast.—These are especially abundant at 
those places where cliffs of boulder-clay or drift are seen. 
Many of them are found 
lying just at the foot of the cliffs, having only recently fallen from them; and others 
which were picked up as pebbles on the beach have doubtless, for most part, been 
derived from the drift also. 
Ailsa Craig, Riebeckite Rock or Paisanite 
. found on Abermawr beach (frequent), Aberfelin 
beach, Porth-y-Rhaw beach. 
(It is interesting to note that a boulder of this was also found in the Lower Boulder- 
Clay at St Nicholas, not far from Abermawr.) 
Granites from the Dalbeattie area, several varieties 
Granites of Galloway type 
A fine specimen of a Mica-hornblende-Granite, identical 
with that of Auchencairn, Kirkeudbrightshire, 
Mull of Galloway Granite 
Another variety from same area 
A Gneissose Granite from Criffel 
Granite or Quartz-Diorite from head of Teach imoens 
South of Scotland, 
Biotite Granite, Loch Dee, South of Scotland 
A Diorite identical with that of a dyke near Guienen 
Isle, Colvend shore, south of Dalbeatie, 
Other Diorites from the Galloway area . 
Hornblende-porphyrite identical with one found south 
of Castle Douglas, Kirkcudbrightshire, 
Other Hornblende-porphyrites of the Galloway country . 
Hornblende-biotite-porphyrite, Wigtownshire . 
Silurian grits, South-West of Scotland 
Muscovite-granite, Foxdale, Isle of Man 
Andesites, Rhyolites, and altered Tuffs of the Bomewdale 
series, 
Reddish Quartz-porphyry, probably from Cushendale, 
Antrim, 
Reddish granophyres and micro-granites, mostly North- 
East Ireland, but some possibly from West of 
Scotland, 
A gneissose Grit—locality unknown 
Carboniferous Limestone 
Gannister : 
A Muscovite-granite, ait aherbalitie a, some Bogie 
locality unknown. 
. found at Pwll Gwaelod beach (frequent), Aber- 
bach beach (near Dinas). 
Whitesand Bay, Aberbach (near Dinas), 
Pwll Gwaelod, Gwhert (near Cardi- 
gan). 
Abermawr. 
Pwll Gwaelod. 
Gwhert (near Cardigan). 
Pwll Gwaelod. 
Pwll Gwaelod. 
Abermawr, Gwhert (near Cardigan). 
Abermawr, Whitesand Bay. 
Abermawr (frequent), Aberbach (near 
Dinas), Abereiddy. 
Pwll Lan-ddu. 
Pwll Gwaelod, Aberbach (near Dinas), 
Abermawr (frequent), Whitesand 
Bay. 
Pwll Gwaelod. 
Abermawr. 
Gwbhert (near Cardigan). 
Abermawr, Aberbach (near Dinas). 
Porth-y-Rhaw, Abermawr, Whitesand 
Bay. 
Pwll Lan-ddu, Gwhert (near Cardigan), 
Aberbach (near Dinas). 
Porth Sele 
Gwhert (near Cardigan), 
Abermawr. 
Abermawr. 
