220 Proceedings of the Royal Irish Academy. 



The papers of Scott and Haughton influenced Mr. "W. H. Stacpoole 

 Westropp,^ who urged that there was an essential difference between 

 the granites of Wicklow and those of Donegal, the former being clearly- 

 intrusive and the latter metamorphic. Dr. Haughton^ had to some 

 extent emphasised the difference by regarding the granite with black 

 mica as typical of County Donegal, which may be true of the surface 

 as now revealed to us ; I believe, however, that this apparent minera- 

 logical difference is due to the position of the broad natural sections 

 in regard to the intrusive mass as a whole. The prevalence of black 

 mica, from this point of view, simply indicates our nearness to the 

 schists along the crests and flanks of great arches which are now 

 occupied by the granite (see figure on p. 225). 



"When, in 1871, the late Professor A. H. Grreen,^ in ignorance 

 of the literature already published on the subject, supported the 

 metamorphic view in somewhat exaggerated detail, his paper met with 

 a cold reception. His opponents, however, knew but little of the 

 petrological difiiculties of the country which he had visited ; and his 

 paper, as finally published in the Geological Magazine, to some 

 extent explained the position he had adopted. He dealt with the 

 Dunlewy district, which may be cited as an illustration of that which 

 we are now discussing ; and his error, in. face of the frequent inter- 

 lamination of the granite and the schists, seems excusable when we 

 consider the controversies of more than thirty years ago. He was 

 without microscopic assistance, and seems to have done little to 

 deserve the intemperate and personal onslaught made on him by Prof, 

 David Forbes* a few months later. 



Dr. C. Callaway^ rer^ognised that the granite of Barnesbeg had 

 penetrated along the foliation-surfaces of the associated schists ; but 

 th.e apparent sharpness of the included fragments, when viewed with 

 the naked eye, seems to have deceived him, as it has done observers 

 in other countries. He was thus led to deny any process of absorption, 

 and consequent modification of the granite, though the microscope is 

 not needed for its appreciation at Cashel Hill near Portnoo, and at 



1 Letter on " The Origin of Granite, " Geol. Mag., 1867, p. 622. 



2 Op. cit., Quart. Journ. Geol. Soc. London, vol. xviii. (1862), pp.410 and 417. 

 ^ Abstract of eleven lines in Quart. Journ. Geol. Soc. London, vol. xxvii. (1871), 



p. 449 ; and " Notes on the Geology of Part of Co. Donegal," Geol. Mag., 

 1871, p. 553. 



* " On the Geology of Donegal," Geol. Mag., 1872, p. 12. On Dunlewy, see 

 J. R. Kilroe, Mem. sheets 3, 4, etc. (1891), p. 71. 



5 Op. cit., Quart. Journ. Geol. Soc. London, a^oI. xli. (1885), pp. 224 and 229. 



