ON THE GEOLOGY OF THE LAKE DISTRICT OF KILLARNEY. 113 
attention was directed to this interesting fact by Sir Denham Nor- 
reys, of Mallow Castle, to whom is due the credit of having first 
observed this trap more than fifteen years ago, and it has not 
been recorded on any Geological Map. 
In alluding to the drift of the Killarney district, he remarked 
the occurrence of large, angular, perched boulders of green grit, on 
the top of the mass of coarse angular drift which lies directly to 
the north of the Devil’s Punch-bowl, and which dams up the water 
of that singular lake. These perched rocks occur at a height of 
Perched Boulders of Green Grit, summit of mass of angular debris, north side 
of Devil’s Punch-howl Lake. Elevation of Boulder above the sea, 2319 feet. 
2319 feet above the sea, the greatest elevation at which such boulders 
are observed in this district. The sea of the glacial drift period, 
must, therefore, have covered this spot in sufficient depth to have 
floated ice blocks capable of bearing and transporting boulders of 
many tons in weight. 
If now we suppose the sea, at this presumed level, to have ex¬ 
tended over the district just described, we find that the summits of 
Purple Mountain, Tomies, the Reeks, Carrantwohill, Benkeeragh, 
Skregmore, and Sugarloaf Mountains would have formed a group 
of islands, extending in an E. and W. direction, with the Black Val¬ 
ley as a deep sea channel, and the Knocknabreda and Cromagloun 
ranges as rather shoal water. It was remarked that the summits of 
the hills just named are all regularly escarped, and covered with 
angular debris , or shingle, the result of atmospheric rather than of 
aqueous agency. 
