Stratified RocJcs near Killarney and Did)lin. 163 



Currawntoohill mountain*, from whence dipping to the south- 

 ward it is covered by siliceous sandstones of a greenish or 

 brownish colour;" and this view is illustrated by a section 

 given in Plate I. fig. 3, which, together with those contained 

 in your Magazine, exhibit the whole of his views on the sub- 

 ject. 



For the sake of clearness, I have also prepared two sec- 

 tions passing nearly through the same line of country as those 

 given by Mr. Hamilton, from which it appears that the old 

 red sandstone on the summit of MacGillacuddy's Reeks, rests 

 conformahly on the schistose rocks of the gap of Dunloe, 

 which Mr. Hamilton terms Cambrian ; and that the apparent 

 unconformability which is visible nearly in the centre of the 

 gap between the chloritic quartz rock and the old red sand- 

 stone, has been occasioned by a great north-west and south- 

 east fault, which crosses the gap of Dunloe nearly at right 

 angles, and extends from thence in a south-eastern direction 

 along the northern declivities of the Purple, Toomies, and 

 Glena Mountains, from whence in continuation it reaches the 

 lower Lake of Killarney, near the Glena Cottage Banqueting 

 House, thence it crosses Brickeen Island, and passing through 

 Turk Lake reaches the north base of Turk mountain. 



This fault may be said to form the key to the geology of 

 the Killarney district, as it explains the apparent anomaly 

 deducible from the persistent dip to the south of the strata 

 on both sides of Glena Cottage and Brickeen Island, which 

 might lead, and has led incautious observers to infer that 

 the strata belonging to the transition slate series which occur 

 to the south of the fault rest conformably on the top of the 

 old red sandstone of Brickeen Bridge, of the northern part of 

 Brickeen Island, and likewise on the carboniferous limestone 

 east of Turk Cottagfe. 



In expressing my view of the geology of the district, I shall 

 commence with the west side of the Gap of Dunloe; but here 

 my section, Plate II. fig. 1, is so different from Mr. Ha- 

 milton's, that it is with difficulty we can recognise them 

 as being intended to represent the same locality ; yet such is 

 the case. Of the accuracy of my own section I entertain no 

 doubt, having made it with great care. 



In taking a sectional view of the strata as exhibited on the 

 west side of the Gap of Dunloe, the first beds visible at the sur- 

 face consist of a reddish gray quartzose rock belonging to the 

 old red sandstone formation. These are succeeded by a 

 series of thick beds, of coarse-grained conglomerate com- 

 posed of rounded pebbles of white quartz, varying in size 



* The highest of the Reeks. 



M2 



