THE TRAPPEAN ROCKS OF KILLARNEY. 
169 
lines of stratification are clearly seen in the trap. It varies in cha¬ 
racter from a hard, granular, green, flaky felstone, in places ashy and 
porphyritic, to a green ash. 
Near the summit of Eskduff Mountain, the trap forms high and 
precipitous cliffs, and a little south of the summit, lines like bedding, 
dipping south, are seen in it. 
In places the grits and slates appear extending into the trap, 
which rests conformably upon them, the boundary between the two 
being deeply indented, in consequence of the sharp flexures into 
which they are thrown. At the south end of the valley the stream 
turns abruptly towards the west, so as to give this glen the same 
form as the Horse’s Glen. The trap ends at the stream, dipping south, 
and none being seen to the south of it. The southern slope of the 
mountain towards the Horse’s Glen is covered with heather; and 
no rock is visible further than about half-way between the sum¬ 
mits of Eskduff and Stoompa. 
On the east side of the Cappagh Yalley, the mountain Benaun- 
more is one mass of felstone, in which lines like stratification are 
seen in places, dipping south at 40° generally. The trap varies from 
a dark-green compact felstone to a green porphyritic ash. In some 
places it is traversed by joints which give it a columnar or prisma¬ 
tic structure. This structure is finely exhibited on the eastern side 
of Benaunmore, where there is a remarkable ravine or cleft in the 
mountain, running N. W. and S. E., which is most likely a line 
of fault. The columns are seen on the east side of this ravine for a 
distance of about three-quarters of a mile. Where first seen at the 
north end of the ravine, they incline to the south at an angle of 50° 
or 60°; but further south they become vertical; some of them are 
fully 200 feet in height. They are generally irregular five or six- 
sided prisms, and are composed of dark-green compact felstone. 
The remarkable appearance that these columns give to the moun¬ 
tain scenery in this place renders it well worthy of a visit, even from 
an ordinary observer. In some places dykes are seen cutting across 
the columns, formed of white or pink compact felstone. This ravine 
terminates at a little mountain lake, called Lough Nabroda, the 
columnar structure ending about half-way on the west side of the 
lake. The trap on the eastern side of the ravine is different from 
that on the west. The columns are seen in places, but are not so 
extensive or massive. The trap on the east side extends farther 
Vol. VII. S 
