216 SIR ARCHIBALD GEIKIE ON THE BASIC AND [May 1894- 



the gabbro and. granophyre at Meall Dearg, in Glen Sligacban, Skye r 

 which is disputed by Prof. Judd, was accurate ; that the granophyre 

 (or granite) there sends abundant dykes and veins into the gabbro ; 

 that Prof. Judd's so-called ' inclusions ' are, as might have been 

 surmised, portions of these dykes and veins ; and thus that the 

 evidence which he has adduced affords additional and crushing 

 testimony to the truth of my observations. "When he was opposing 

 the deliberate statements of a previous observer, it was surely his 

 bounden duty to examine the alleged facts, on the ground, with 

 scrupulous diligence. I regret that I must now show that he has 

 failed in this duty, for, had he used even the most ordinary care, it 

 is incredible that he could have missed the evidence on which I 

 relied. That geologists may be able to judge between us, I have 

 had some of the visible sections photographed, and I appeal to the 

 impartial testimony of the camera in my favour. The evidence from 

 this Skye locality is so abundant and conclusive, and the point to be 

 proved is so simple and elementary, that I cannot help feeling as if 

 some apology were due to the Society for the necessity of bringing 

 the subject before it. 



II. The Gabbro Bosses. 



The tracts of gabbro among the Western Isles have not yet been 

 traced out in detail upon maps of a large scale. Until tbat task is 

 completed it will hardly be possible to show how complex these 

 areas are, alike in their tectonic and petrographical features. I 

 have referred to this complexity in my memoir already cited, and 

 have given the evidence which indicates that the larger bosses were 

 probably the results of many successive protrusions. 1 



The ridge referred to by Prof. Judd as Druim an Eidhne, the 

 site of his ' inclusions,' is marked on the 6-inch Ordnance map as 

 forming the south-eastern portion of a rugged spur which, descend- 

 ing from the crags overlooking Harta Corry, is crossed by the foot- 

 path to Coruisk. On the map accompanying his paper Prof. Judd 

 inserts his ' enclosures ' only on that limited portion of the ridge, 

 but he would have found that the evidence on which he relied 

 extended much beyond the narrow limits to which he has restricted 

 it. Indeed, the most striking evidence of the occurrence of granitic 

 material within the area of the gabbro lies to the north of these 

 limits. 



The whole ridge which ascends from the hollow of Strath na 

 Creitheach between the two lochs, and, including the Druim an 

 Eidhne, rises into the rugged ground that bounds the eastern side 

 of Coire Pdabhach, affords an admirable illustration of the really 

 complex nature of tbe gabbro bosses. Instead of being composed 

 of one rock belonging to one great interval of eruption, it includes 

 at least five varieties, exclusive of the granophyres, indicating a 

 succession of emissions. These rocks are not disposed at random, 

 but exhibit a certain roughly-bedded arrangement. Conspicuous 



1 Trans. Koy. Soc. Edin. vol. xxxv. (1888) p. 140. 



