Geological Relations of the East of Ireland \ 221 
§ 121. The rocks of the transition class exposed to our obser- 
vation upon this coast, are clay slate, clay slate conglomerate, grey- 
wacke, and greywacke slate, interstratified with limestone, limestone 
conglomerate, trap, and porphyry. 
§ 122. Portrane* and Dunabate form nearly a peninsula, being 
flanked on the north and south by inlets from the sea. The former 
is the more considerable elevation of the two, being separated from 
the latter by an intervening hollow. 
The eastern part of the headland of Portrane consists of transition 
rocks. In the south-eastern quarter, under Portrane house, the hol- 
low, which winds toward Dunabate, is occupied by red sandstone 
conglomerate; and this rock appears to constitute the whole of the 
rising ground of Dunabate, at the foot of which the new chapel 
may be seen founded upon the sandstone. To the westward of 
Dunabate, the country consists of floetz limestone, and the western 
part of Portrane, on which the mansion stands, appears also to be 
composed in part of limestone ; for, in sinking a well there seventy 
feet deep, fifty-nine feet passed through soil, and the last eleven 
feet were sunk in limestone ; but this is probably connected with the 
transition rocks in the eastern quarter. The actual contact of the 
rocks here noticed cannot be traced, but from their general position 
I am led to infer that the sandstone conglomerate rests upon the 
transition series : and we shall now follow the latter in the line of 
their succession around Portrane headland. 
The north side of this promontory exhibits rugged rocks com- 
posed of massy unstratified greenstone, which extend to the east- 
ward about sixty yards beyond the quay. This greenstone is com- 
monly a compact felspar coloured by hornblende, varying from a 
* The seat of Geo. Evans, Esq. to whose friendly attentions I am much indebted in the 
examination of this coast. 
