106 MR. GARDINER AND PROP. REYNOLDS ON THE [June 1 9T4, 



the lower part of Two-Stream Valley (see fig. 1, below). Although, 

 as a rule, phenocrysts are seldom observed in a hand-specimen, 

 at the western end of the area, near the Curraghrevagh stream, 

 numerous porphyritic albites occur. 



{b) The Sedimentary and Pyroclastic Rocks. 



Although the various rock-types are intimately associated, it 

 seems better in describing them to adopt a petrological classification 

 rather than a geographical one. 



(1) The Coarse Breccias. 



As in the Kilbride area, these rocks consist of spilitic and 

 felsitic breccias, the two kinds of fragments being occasionally 

 intermingled. Breccias do not cover nearly so extensive an area 



Fig. 1. — Diagrammatic sketch showing the relations of the tuffs^ 

 cherts, and spilites in Two-Stream Valley, Nafooey. 



T 



[Approximate scale : 1 inch = 1^ feet.] 

 p— PiUows.T T = Tuff. C± = Chert in irregular patches. C. 2 = Bedded chert. 



relatively to the spilites as they do at Kilbride. The large mass 

 ofJ : breccia seen west of Finny, in the Kilbride area, continues 

 across the Finny River into the Lough Nafooey area; but the 

 eastern part of the mass is largely hidden by alluvium, while the 

 western part is much interrupted by intrusions of felsite. A band 

 of coarse breccia, which lies along the southern border of this 

 felsite, is easily traceable, owing to its conspicuous appearance. 

 It consists of angular fragments of a fine-grained felsite weathering 

 white, and of red and green chert, enclosed in a green matrix. It 

 resembles very closely the band of breccia associated with the 

 DidymograpUis-extensus Shales seen on the southern slopes of 



