CRYSTALLISE SCHISTS IXIO IGXEOIS EOCES 13" CO. GAL "WAY. 521 



these (fig. -1) : in another, only one. Sometimes they are mere flakes. 

 They are isolated from the main masses and from each other by 

 granite. It would appear as if they were separated from the parent 

 blocks by exfoliation. As the granite rose np between the blocks, 



Pig. 4. — Section of Diorite (? exfoliated) in Granite. 



thev would become strongly heated, and the outer zones, being 

 hottest, would by their greater expansion split away concentrically. 

 That the exfoliated fragments retain their parallelism to the adjacent 

 margin of the main masses is a .remarkable fact, to which I shall 

 return. 



Ground souili of Glen J. dough, 



Leaying the hotel in a southerly direction, we pass over crystalline 

 limestone, quartzite, and a considerable thickness of hornblende- 

 schist. A little further south lies a large mass of rock, chiefiy 

 hornblendic, which is said to graduate into the associated gneiss 

 and schist'"' *. Xear where " 5" is marked on the map. there is a 

 singular entanglement of schist with granite and diorite. The 

 rocks are heavily glaciated, so that it was impossible to obtain large 

 specimens ; but eyen the small fragments collected clearly show that 

 there is no passage between the schists and the igneous rocks. The 

 schists are intensely contorted and much shattered, and the granite 

 or the diorite sometimes finds its way eyen between adjacent folia, 

 and is mixed up with the schists in inextricable confusion. Several 

 contact-specimens have been microscopically examined, and Prof. 

 Bonney, at my request, has devoted special attention to them. He 

 thinks there is no doubt that they are a case of intrusion of granite 

 into a fibrolite-schist : but the structure of the granite is irregular 

 and peculiar, owing probably to its contact with the schist. 



It is a striking fact that, in this locality, detached folia, or bundles 

 of folia, frequently preserve an approximate parallelism to the 

 foliation of the adjacent schists. This might appear to be a strong 

 piece of evidence in favour of the metamorphic hypothesis. It is 

 not easy to "believe that an igneous rock could have been intruded 

 amongst masses and fragments of schist without destroying the 

 parallelism of strike. I would, however, venture to urge that the 



* Survey AEemoir, 93. 94. p. 139. 



