■i go THE BRITISH NATURALIST. [August 



than the rest, and presents chiefly the white cliffs and the caverns at 

 the base. 



The caverns that one sees in the limestones of Derbyshire or York- 

 shire are the watercourses of streams, which falling on the surface 

 percolate through the strata, dissolving the rock as they go, until the 

 united drainage finds vent in the shape of a goodly river rushing to 

 light in full force. The same process goes on near Killarney, as I 

 shall have occasion to mention. But the caverns by the lake side are. 

 made by the lapping of the water against the foot of a cliff, eating it 

 gradually away until the roof seems to have no visible support. It is 

 not all pure destruction, for the water becomes so heavily charged with 

 carbonate of lime that it crystallizes afresh on the floor of the cave, 

 and provides a coating of stalagmite. This process may be studied on 

 dry land, for the lake, having stood at higher levels in former times, has 

 left specimens of rocks with eaten out caverns, now high and dry, 

 above the present surface of the water. They form very picturesque 

 objects, as the grey limestone shows through a vestment of green fern 

 and shrub, and suggest the similarly overgrown Gothic ruin. 



The scenery of Killarney owes much of its charm to the profusion 

 of its vegetation, and especially to the majesty and full development of 

 its timber trees. This, no doubt, is in great measure the result of the 

 warm, moist climate and of the freedom from frost which the district 

 enjoys ; but this is not all. The trees, such as the oak and the ash and 

 the arbutus, grow very well on the Old Red, but they never attain the 

 beautiful proportions that the same trees exhibit in the Muckross 

 demesne, where the subsoil is lime. The varnish on the leaves of the 

 holly shines out with a beauty that no Lancashire holly is permitted to 

 show. The ivy, too, is of a superlative sort. But just outside the 

 Muckross demesne, where mountain and wood and water combine to 

 present the most beautiful aspect of nature, is a geological phenomenon, 

 one of the most remarkable in its way in Ireland, the product of the 

 glacial era — this is the western edge of a rich bed of drift. It consists 

 of a huge bed of sand freely interspersed with blocks and pieces of Old 

 Red, and is on the average about 250ft. deep. Proceeding westwards 

 it extends from Mill Street to the Muckross demesne (a distance of 

 over 20 miles), and is then conspicuous by its absence to the Gap of 

 Dunloe, but is thence again apparent and dies away on the shores of 

 Dingle Bay. 



In the ascent of Mangerton you cross the drift in a distance of about 

 two miles. Patches of deposit of similar material occur at varying 

 heights up the mountain side, the highest being at 2,200ft., where it 

 dams up the water in the Devil's Punch Bowl, and so furnishes a 

 collection reservoir for the Killarney water works, eight miles distant. 



(To be continued.) 



