434 IProc. B.N.F.O.^ 



(i) mountains of accumulation, (2) mountains of elevation, and 

 (3) mountains of circumdenudation. A consideration of the 

 Mourne mountains itself, coupled with the evidence of dykes, 

 has led geologists to declare that it is much younger in age than 

 the granite of the Newry tO' Rathfriland and Castlewellan area, 

 from which it is entirely separated by intervening Silurians. 

 In composition and character it resembles strongly the volcanic- 

 ally-formed rhyolites of County Antrim, such as occur at 

 Tardree Hill and Templepatrick. It is, therefore, believed to 

 be of Eocene age, contemporaneous with the rhyolites of 

 Antrim ; and consequently coming in, as regards geological 

 time, between the lower and upper basaltic outflows of the 

 same county. A recent study of the subject has led Professor 

 Cole to speculate thus — ^"Possibly the little dome of Ailsa 

 Craig, which has suffered so severely from denudation that its 

 pebbles lie scattered by hundreds all down the Irish Coast, 

 was a bold mass of the same age as the Mournes and Arran, 

 and became almost destroyed by the severities of glacial times. 

 In any case we can now follow out the line along which granite 

 intruded in Eocene times, from the south of Carlingford Lough 

 to the smooth red hills of Skye." Having endeavoured to con- 

 jure up before the mind's eye the vast procession of changes- 

 w^hich the Mournes have witnessed in the process of their 

 evolution, we are inclined to fall back, for a descriptive sum- 

 ming up, upon the lines of Tennyson, himself an ardent 

 geologist — 



" There rolls the deep where grew the tree, 



O earth, what changes hast thou seen ; 

 There, where the long street roars, hath been 

 The stillness of the central sea. 



" The hills are shadows, and they flow 



From form to form, and nothing stands ; 

 They melt like mist, the solid lands, 

 Like clouds they shape themselves and go." 



(Applause.) 



