190b-191U.I 27 1 



at random at Drumfane it was found that twenty-one were rhyolite, 

 four chalk, two flint, two dolerite, one Cushendall porphyry and 

 seventy basalt. A hundred similar specimens examined at Brough- 

 shane yielded seventy-six of basalt, four of flint, and twenty of 

 chalk. Clearly, then, the deposits at the latter place are more 

 definitely local j rhyolite seemed to be absent, whereas at the 

 Drumfane pits it was common. One igneous rock, which has 

 never been seen in situ locally, but which is not uncommon in the 

 glacial deposits of the North-east and East of Ireland — namely, 

 the Ailsa Craig riebeckite rock, could not be traced at either 

 Drumfane or Broughshane. 



With regard to the acid igneous rock rhyolite, it may be 

 observed that the main outcrop occurs at Tardree Hill, north-east 

 of the town of Antrim. The earlier geologists misnamed it 

 trachyte, and it was supposed to be confined to the Tardree area. 

 At the time the Ballycloughan rhyolite quarry, visited on Saturday, 

 was in active use the stone extracted therefrom being looked upon 

 as a sandstone of carboniferous age, and this misinterpretation led 

 to a fruitless series of borings in search of coal in the immediate 

 vicinity. To the few who even at that time recognised the 

 volcanic character of the rock, the prospecting for coal at Bally- 

 cloughan was rightly characterised as a hopeless undertaking. So 

 far as the County Antrim is concerned the exposures of rhyolite 

 in situ have been traced in a more or less direct line from the 

 village of Templepatrick in the south to Cloughwater in the north. 

 The rock at Tardree is more granitic in texture than elsewhere. 

 The outcrop in the bog at Cloughwater forms a low boss, shaped 

 somewhat like an inverted saucer, and although basalts outcrop 

 everywhere on the surface of the country around no junction of 

 the rhyolite and basalt can be seen, owing to the engirdling deposit 

 of peat. Whether this Cloughwater protrusion is really a volcanic 

 neck or merely an isolated mass detached from a larger lava flow 

 is an interesting problem. The fact that those inter-basaltic 

 deposits of County Antrim known as bauxites are known to have 



