PLUTONIC KOCKS OP GAEABIL HILL ANB MEALL BEEAC. 121 



farther from the outer walls of the complex, the granitite and 

 diorite have completely amalgamated on their edges. Another part 

 of the complex exhibits a still stranger phenomenon. A vent-like 

 mass of light grey diorite has penetrated a more basic mass, con- 

 taining numerous porphyritic crystals of hornblende. At the 

 junction of the two we can see that the newer rock has torn out the 

 pasty magma of the older and arranged the porphyritic crystals of 

 hornblende in parallel planes, but apparently without injuring them. 

 The phenomena seem to point to the fact that the segregation 

 mainly took place in a deep-seated magma before intrusion into the 

 present position of the complex. Further, while the law of decreas- 

 ing basicity was clearly true of the rock ' masses,' the reverse was 

 the case with the dykes. The quartz-porphyries, so far as the 

 speaker knew, were cut by the lamprophyres and were always the 

 older rocks. This seemed to point to the whole of the phenomena 

 being due to the remelting of an old magma. The irruptions com- 

 menced with the re-fusing of the base, and ended, in the dyke-stage, 

 with its reconsolidation. 



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