646 



MESSES. J. HORNE AND E. GREENLY ON [Nov. 1 896, 



The orientation of the porphyritic felspars in the granites of 

 Portskerry, again, can hardly be other than a truly igneous 

 structure; also the phenomenon of foliated granites cutting each 

 other's foliation. 



Fig. 4. — Inclusions of hornblende-schist in foliated granite, 

 Altvphurst, Strathy Point. 





[Area represented = about 8 square feet.] 



Introduction of granite was without doubt the final term in the 

 production of the gneissose complex, but everything points to that 

 process having been long and elaborate. Single sections, even, can 

 be seen showing schists powerfully folded, foliated veins intruded, 

 the whole faulted, and new and complex veins introduced (figs. 5 & 6). 

 It is clear that movement must have continued, or recurred from 

 time to time, from the very first glimpse we get of the metamorphic 

 process till . nearly its close, for all veins except the microgranites 

 are cut by faults which are completely ' healed up ' by crystalliza- 

 tion. 



But it is also clear that the whole mass must have remained at a 

 high temperature till the very last, not only from the last quoted 

 fact, but from the absence of any chilled edges whatever, even to 

 these microgranites, which cut every other rock sharply, and are the 

 last members of the whole crystalline series. 



If, therefore, the rocks ever passed through a stage of mere 

 mechanical crushing as a result of these movements (and of this the 

 sections observed afford no evidence), such cataclastic structures 

 have been wholly effaced during the later stages of metamorphism. 



The evidence of powerful movement which these schists every- 

 where present certainly suggests that such movement was the initial 

 cause of the whole series of phenomena. 



