158 
JOURNAL OF THE GEOLOGICAL SOCIETY OF DUBLIN. 
CARBONIFEROUS SLATE. 
This formation is very rich in igneous rocks; they make their 
appearance from about the centre of Here Island, and carry on 
until the Carboniferous Slate is lost in the sea at Cahirmore. 
They appear principally in the grits called by Mr. Jukes Coom- 
hola grits, from their being highly developed at Coomhola, near 
Glengariff. They lie lowest in the Carboniferous series, and are 
the principal representatives of it along the north side of Bantry 
Bay, in the Berehaven district,-—there being very little Carboni¬ 
ferous slate proper developed therein. The traps at the Bere 
Island end will be first spoken of. 
In Bere Island the igneous rock seems to be divisible into five 
classes,—conformable and unconformable greenstone, conformable 
and unconformable felstone, and felstone ash. The only legitimate 
beds of ash are felspathic, though most of the greenstone dykes have 
more or less of a flaky structure, resembling ash. The felstones for 
the most part are seemingly conformable,—the greenstones, not. 
At the south-east of the island, under and near Tower No. 3, 
there is a system of conformable felstones, which seem to be con¬ 
temporaneous, as the top of the beds are more or less ashy; and they 
generally become so before dying out. They are of a bluish colour, 
with a few crystals of white felspar widely disseminated through 
them. The blow-pipe has little or no action on them; no green¬ 
stone makes its appearance in this part of the island. 
At the N. W. corner of the island, near Redoubt (No. 5), the 
trap all seems to lie conformable, being chiefly felstone, with one or 
two greenstones. These are traceable a short way to the east, where 
they are lost in the drift. A few of them can be traced as far as 
the Telegraph Tower; they do not go much further, if past it, as 
they are not to be found in the hill at the other side of the drift. 
Going further south, you find the strata and conformable trap 
cut up by a system of dykes; the traceable ones are ashy-looking 
or flaky greenstones; and along the coast are some small felstone, 
which, on account of their small size, are impossible to trace. 
The greenstones run every way; but the principal ones take a N. E. 
direction, and some of them run as far as the Telegraph Tower; 
they dip at an angle of 85° to the N. and N. E., and are on an 
average about 2-J feet thick; some of them end in bosses of a com- 
