114 AUSTRALASIAN ANTARCTIC EXPEDITION. 



It is very interesting to note that Flett finds (p. 74) that there is a transition between, 

 or an intermixture of, the serpentine and the adjacent hornblende schist at the junction 

 at Pol Cornick ; that there is little evidence of crushing to be found in the slides cut 

 from the junction ; that there is a little development of tremolite, and the minerals 

 are exceptionally fresh. It seems reasonable to infer that a primary metamorphic 

 product has arisen at this point as the result of metamorphic diffusion, with the destruc- 

 tion of the hornblende schist-serpentine boundary. This means that the hornblende 

 schist and serpentine have suffered together similar metamorphic processes, and hence 

 we have further justification in treating the serpentine mass as a metamorphic product 

 rather than as a weathered peridotite. 



We may now, perhaps, go further and make reference to the inter-banding of schist 

 and serpentine described (p. 75) as due to folding. Canoe-shaped infolds of fine, rotten 

 hornblende schist are mentioned. These remind us of the lenticular inclusions of the 

 amphibolite dykes in the granodiorite gneiss that have been torn off the main dyke 

 channels at Cape Denison during the metamorphism of the area. Such " infolds " 

 have been referred to as " inclusions " by Adams and Barlow in the Haliburton and 

 Bancroft area in Canada, and considered to be evidence of the lesser age of the enclosing 

 rocks.* As we have found that this is not necessarily the case, we must apply great 

 caution in the interpretation of the folding in metamorphic areas until the field 

 phenomena are better understood. More especially as it is observed by Flett (p. 99) 

 that no part of the gabbro has been folded, and all the movement seems to have taken 

 the form of internal shearing in a large unwieldy mass which would not fold. 



Flett distinguishes two series of hornblende schists in the Lizard, and both are 

 determined as metamorphosed igneous rocks. One series is spoken of as the Landewed- 

 nack schists (p. 46) and the other the Traboe schists (p. 50). The Laridewednack schists 

 are considered to be older than the Man of War gneisses, and the Traboe schists are 

 younger, though Flett acknowledges their inter-relation is difficult to make out. Apart 

 from differences in weathering, the Traboe schists are distinguished from the Landewed- 

 nack schists (p. 51) by the following characters : 



1. Paucity of epidote. 



2. Its relation by folding and transition to the serpentine, for no case is known 



where the Traboe schists occur at any considerable distance from the 

 margin of the serpentine. 



Now the presence or absence of epidote in an hornblende schist depends upon the 

 temperature factor in the metamorphism. Epidote will only form if the temperature 

 is not too high to drive the water out of the molecule. The inference is that the Traboe 

 schists have been metamorphosed at a higher temperature than the Landewednack 

 schists a fact which has no bearing on relative age. If we neglect the doubtful evidence 

 of folding there only remains the fact of transition which, it is maintained, can be 



" Geology of the Haliburton and Bancroft Areas, Ont.," Adams and Barlow. Mem. No. 6 Can. Geol. Surv., p. 62. 



