DTJ NOYER — ON THE SOUTH OE IRELAi^D. 



245 



boulders poised one over the other, and these could only have been 

 placed in their present position by having been slowly dropped from 

 an iceberg as it melted from the heat of summer. Had such a piling 

 of angular blocks occurred under water and within reach of any float- 

 ing mass of ice, it would have been thrown down by the first con- 

 cussion. 



As the land still slowly emerged from the sea, the disintegrated 

 materials from its shores became more or less sorted by the action 

 of the tides and currents, and arranged in certain localities most fa- 

 vourable for their reception. Thus, the low ground which extends 

 from Killarney to Millstreet, lying at the northern base of the 

 mountains commencing at Carrantuohill and Skreaghmore on the 

 west, and including the Reeks, Mangerton, Stoompa, Crohane, the 

 Paps, and ending in the range of the Caherbarnagh mountains on 

 the east, is covered by a thick accumulation of well-rounded, coarse 

 Boulder-Drift, all derived from the rocks of the neighbouring moun- 

 tain chains ; being, in fact, the sweepings of the sea from out their 

 various valleys and gorges. Although this Drift is spread out on 

 the Carboniferous limestone which extends along the flanks of the 

 mountains, it is quite free from any fragments of that rock — a fact 

 M'hich aids in determining the origin of the deposit. The highest 

 elevation to which this Drift reaches up the flanks of the mountains 

 at Mangerton is about 600 feet; and in the neighbourhood of Kil- 

 larney, along the road to Muckross, this deposit is escarped to the 

 depth of 300 feet. 



One of the most clear and unmistakable examples of an erratic 

 ice-borne block, or perched boulder, is to be seen near Kenmare, in the 

 county of Kerry, on the hillside about half a mile to the south of 

 Rough ty Bridge (Fig. 1, p. 2il). It consists of a large and nearly 

 rectangular block of grey, thin-bedded, cherty limestone, formed of 

 a series of beds which have come away from the main mass along 

 two sets of joint planes, which cut each other nearly at right angles. 

 This boulder is known by the name " Cloughvorra ;" it measures 

 26 feet from north to south, 16 feet from east to west, and is now 

 about 15 feet to its highest point above the ground. This remark- 

 able block rests directly on purple grits and slates of the Old Red 

 Sandstone, the beds of which dip to the N.N.W. at 60°. The ele- 

 vation of " Cloughvorra " above the sea is 260 feet, while no lime- 

 stone in the valley of the Roughty river reaches a greater elevation 

 than 200 feet, and the average height of the limestone in the valley 



