706 Proceedings of the Royal Irish Academy. 
The Croagli Patrick range and the country immediately south of 
Clew Bay was not worked by me. But I am aware that the Louisburgh 
series and the Creggaunbaun series lie unconformably on the older 
rocks of the Croagh Patrick range ; in fact, in the portion of the 
Creggaunbaun basin that came into my area there is a conglomerate 
lying unconformably on the upturned edges of the Doolough slates. 
In this Paper, however, I will principally confine myself to my 
special work. 
JVorth Boundary of the Killary and SUeve Partry Silurian Basin. — 
To the eastward in the Toonnakeady district (Slieve Partry) the 
Silurians are principally false-bedded massive conglomerates, con- 
taining many rounded pieces of granites and other rocks fi^om the 
country to the south-westward; but they also contain frag^ients of 
the rocks in the country to the northward — conspicuous pebbles being 
those of jasper, found in situ in the Aille river valley. Other rocks of 
the north country — not to be found in the country to the south — that 
occur in the conglomerate — are fragments of the pebbly sandstones 
south of TVestport and of the quartzose grits of the ErrifE valley. 
The massive conglomerate of SKeve Partry to the westward is 
replaced by massive pebbly grits, the conglomerates disappearing 
nearly altogether west of the Aille river valley ; they, however, 
again appear west of the Doolough valley, but not of the same 
massive character. Parther west they are very conspicuous on the 
western flanks of Mweelrea, but more especially near the Atlantic 
in the Dooaghtry, Dadi^een, Doovira, and Uggoal outliers. 
Before proceeding further it should be mentioned that in the older 
rocks to the north there are trap-dykes, conspicuous systems of breaks, 
and the Erriff quartzose grits, all of which come up to, but never 
enter, the Silurian rocks. 
To the eastward, coming up through the massive conglomerate, 
are three or four exposures of the older rocks. One, of graptolitic 
black shales, occurs in the Owenbrin valley, to the south of Toorma- 
keady ; two, of baked shales, occur near the village of Partry ; and a 
fourth, of schists, in the hills a little to the westward. 
The eastern portion of the northern boundary of the Silurians is 
more or less obliterated by bog and drift, while it has been broken by 
upthrusting and other faults ; still, in numerous places the unconfor- 
mability between the older and later rocks is apparent — the first 
striking obliquely at the other, while the Silurian dip south, away 
from them at low angles. This is very conspicuously seen south of 
Tawnyard Lough, where the older rocks strike nearly at a right angle 
