Yol. 56.] IGNEOUS ROCKS OP COUNTY WATERFORD. 677 



felsite-porphyry ofBallyvooney Cove encloses portions of the 

 intrusive felsites which have been injected into the black slates at 

 that spot. 



Between Knockmahon and Bunmahon a remarkable purplish 

 or dark-greenish augite-porphyrite is exposed in the series 

 of small coves. It contains in parts numerous small xenoliths, 

 and is associated with a large mass of agglomerate and 

 tuff composed of fragments similar to the xenoliths in the 

 porphyrite. The fine purple slates are interbedded with very fine 

 tuffs of similar materials. The solid rock from which many of 

 these fragments are derived is found in juxtaposition. All these 

 rocks have been pierced first by veins of somewhat similar constitu- 

 tion and by dolerites, subsequently by felsites and f elsite-porphyries 

 (see fig. 8, p. 668), and have also suffered mechanical disturbance. 

 Their true place in the bedded series can only be conjectured, no 

 other rocks of similar character being found elsewhere in this 

 district. It should be mentioned that on the Geological Survey 

 Map- (Sheet 178) an asterisk indicates that fossils have been found 

 near this spot in the midst of what is coloured as greenstone-ash. 

 ■' Pelspathic grits and ashy shales ' are mentioned by Sir Archibald 

 Geikie r as occurring here. 



Another rock which bears some resemblance to this augite- 

 porphyrite occurs on the west side of Bunmahon Head, where it 

 penetrates the green tuffs. It is a dark-greenish rock with fine 

 fresh phenocrysts of augite visible to the naked eye. The other 

 occurs below the altered Tramore Limestones, the base of which 

 it penetrates, in a cove on the west side of Ballydouane Bay, 

 but its resemblance is chiefly confined to the presence of large 

 phenocrysts of augite. 



In the next place may be mentioned a group of peculiar dark- 

 grey or greenish rocks at Eoilnaneena Cove, Tankardstown, 

 resembling some kinds of trachytes and in many respects bosto- 

 nites (see Types H & I, Eelsites, p. 683). These rocks are earlier 

 than the felsite-porphyry and the pale-grey dykes and veins, both 

 of which pierce them ; but they are themselves probably intrusive 

 in the purplish and mouse-coloured slates exposed in the face of the 

 cliffs a few yards to the west. At the critical points, however, the 

 whole section is much obscured by landslips and debris from the 

 abandoned workings for copper, the presence of which is abundantly 

 evident. 



Bocks of similar character are found on the east side of 

 Bunmahon Head, where some of them appear to be connected 

 with a neck on the foreshore, and others pierce the green Bun- 

 mahon Bock (see p. 678) as dykes or veins. The presence of 

 similar rocks of uncertain age has also been detected below Knock- 

 mahon and in Cooneenacartan C o v e, but nowhere else along 

 the coast, except perhaps in the coves opposite Carrigaghalia near 

 Tramore, where the pale-grey intrusive sheets in the Dicrano- 

 (/raptus-shales are of a somewhat similar type. 



1 ' Ancient Yolcanoes of Great Britain ' vol. i (1897) p. 249. 



