THE METAMORPHIC ROCKS OF ADELIE LAND STILLWELL. 189 



Similar rocks have been described by Holland as norites among the charnockite 

 series of India.* The augite norite and the hornblende augite norite present analogies 

 to the plagioclase pyroxene gneisses. Yet they are, perhaps, more comparable with the 

 basic gneisses at Madigan Nunatak and Aurora Peak ; but the latter rocks have a direct 

 relation to the Cape Gray dykes. 



In his description of plagioclase pyroxene rocks from Parasnath and the I jri Valley, 

 from the Madras Presidency and Bengal, Holland f describes the original augite as 

 darkened, almost blackened, by minute rods and plates forming an ordinary example 

 of schillerisation. The hornblende which is derived from the augite is free of such 

 inclusions. This augite reads precisely similar to the primary dusty augite that has 

 been described from Cape Gray and Stillwell Island. The development of secondary 

 pyroxene has not occurred in the Indian rock as in the Antarctic. 



In some of the pyroxene granulites or basic charnockites from the neighbourhood 

 of Salem, Holland J describes a corona of garnet around the hypersthene. This seems 

 to be similar to the corona around the pyroxene in the garnet plagioclase pyroxene 

 gneiss (No. 935) from Stillwell Island. In this publication a sketch is given of hyper- 

 sthene with a corona of spongy garnet. This spongy garnet appears to be similar to 

 what we have referred to as diablastic pyroxene, or vermicular pyroxene, which is very 

 well developed in some of the Stillwell Island rocks. This material is sometimes isotropic, 

 sometimes with very low polarisation colours, but sometimes it shows the brighter 

 polarisation colours of pyroxene. Possibly it is not constant in composition and 

 represents some intermediate form between garnet and pyroxene. The separation of 

 quartz in this garnet-pyroxene reaction is noticed in the Indian rocks as well as in the 

 Stillwell Island rocks. 



Similar pyroxene gneisses have been described in many parts of the world, in Canada, 

 in Scotland, in Madagascar, from the moraines in South Victoria Land, and in many 

 other places. 



" Charnockite Series," T. H. Holland, Mem. G.S.I., XXVIII., pt. 2, p. 166. 



t " Origin and Growth of Garnets," T. H. Holland, Reo. G.S.I., vol. XXIX., p. 20. 



J " Geology of the Neighborhood of Salem," T. H. Holland, Mem. G.S.I. 30, p. 12. 



