168 
JOURNAL OF THE GEOLOGICAL SOCIETY OF DUBLIN. 
contortions in beds of purple grit and slate, the trap is seen plainly 
.overlying them, conformably, and similarly contorted. Its general 
character is that of a pale bluish-green felstone, having in places 
concretionary nodules, but it varies from this to a compact green 
or purplish gray felstone, having a few scattered crystals of felspar. 
It is in some places highly porphyritic. The beds at and near the 
junction with the grits and slates are almost invariably ashy beds, 
varying from a dark green to a pale yellowish-green flaky ash, 
generally porphyritic. Some beds of dark-green decomposed ash 
extend from the southern end of Lough Managh, as far as a point 
opposite the middle of the north shore of Lough Errogh, and are 
then seen no more. They appear to dip south at 20°. On the 
western side of the glen, to the north of Lough Managh, is seen a 
dyke-like mass of hard, dark-green felstone, cutting across beds of 
green grit, which dip S. 45° E. at 55°. Its direction in plan is 
N.W. and S.E. Higher up on the cliff it is seen resting on beds of 
dark-gray, gritty-looking ash. Several long fissures are seen on both 
sides of the glen, resembling the walls of dykes, the dykes them¬ 
selves having weathered away. 
On the northern slope of Stoompa, three-quarters of a mile east of 
the south end of Lough Garagarry, is an isolated patch of trap, con¬ 
sisting of a green flaky felstone ash (with crystals of felspar) ap¬ 
parently dipping S. at 80°. Its relative position to the adjacent se¬ 
dimentary rock is not discernible. 
The mountains Eskduff, Benaunmore, and Crohane, lying to the 
east of Stoompa, and south and south-east of Lough Guitane, are 
chiefly composed of felstone. Between Eskduff and Benaunmore is 
a picturesque valley, about one mile in length, through which the 
Cappagh stream runs north and south into Lough Guitane. On 
entering this valley from the north side, at about one-eighth of a mile 
south of a small lake called Lough Nabrean, the trap is seen appearing 
on the west side. Its relative position with the adjacent sedimentary 
rocks is not plainly seen, but it has the appearance of resting conform¬ 
ably upon them, the dip being S. at 60°. 
It extends westward to a point about one-fourth of a mile from 
the isolated patch before mentioned, on the north slope of Stoompa; 
where it ends, there seems to be a fault bearing N. W. and S. E., 
inasmuch as purple grits and slates strike abruptly against it. No 
