676 ME. F. E. COWPEE EEED ON THE [NOV. ICJOO,. 



cliffs near Sheep Island, piercing the felsites and other rocks 

 there, but they are only distinguishable under the microscope. 

 Some are trachytic and pale grey, but another type is of a darker 

 greenish tint. Yeins with a similar behaviour and mostly of a 

 dark-greyish colour occur between this point and the Black Door, 

 Kilfarrasy, where an exceedingly crushed and altered large 

 intrusive mass, of a pale greenish-grey and with a soft soapy 

 feel, is seen to be intrusive in the felsites. Its true characters 

 are doubtful, but it seems to resemble the keratophyres. A 

 few small veins penetrate the rocks in the cliffs of Kilfarrasy 

 Strand, and one of a trachytic character is noticeable on account 

 of its anticlinal curvature. There are several similar veins of 

 much the same petrological character between this spot and Green 

 Island, and in some cases they enwrap the agglomerate in the 

 felsitic vents. More veins, also piercing the felsites and exhibiting 

 the same pale-grey coloration, occur inAnnestown Bay, along 

 Morageeha Strand, where they invade the slates but have not 

 suffered the same crushing; others are noticeable near the Long 

 Rock, on Knockane Strand, and near Dunabrattin. Nearly 

 all of these are of a trachytic type. It is interesting, particu- 

 larly with regard to their relative age, to find a vein of this 

 character piercing the bostonites at Poilnaneena Cove. 



Below the Knockmahon engine-house a pale greenish-grey 

 intrusive vein penetrates the felsites and other rocks, but is affected 

 by the faults. On the eastern side of BallydouaneBay there 

 is a considerable development of keratophyres, penetrated by 

 some later felsitic veins, but their other relations are not clear. 

 With the exception of a few keratophyric tongues piercing the 

 altered Tramore Limestones in Ballydouane West Bay, but 

 themselves cut by later felsitic intrusives in Killelton Cove, no 

 veins belonging to this group have been observed farther west 

 along the coast-line. 



/. Intrusions of Various Types. 



Among the felsitic rocks mention has been made of several 

 intrusions of f elsite-porphy ries, which, though associated in most 

 cases with the former, do not invariably belong to the same period 

 of activity. 



There is first the grey felsite-porphyry at the western end of 

 Garrarus Strand, later than the felsites, but earlier than the 

 trachytic or andesitic veins. The grey felsite-porphyry at the 

 Long Rock, near Knockane Strand, Annestown, is not 

 clearly of later date than the felsites there exposed, while that at 

 FoilnaneenaCove is later than the bostonites and is associated 

 with a vent. Below the engine-house at Knockmahon the 

 bluish-grey felsite-porphyry is pierced by some of the felsites, and 

 that on the coast nearer Bunmahon breaks through the augite- 

 porphyrite and other rocks; probably that by Bunmahon 

 Bridge is of the same age. The red felsite-porphyry of Bally- 

 douane West Bay cuts through all the other rocks there, so far 

 as can be seen, except the Old Red Sandstone ; and the greyish 



