214 PROCEEDINGS OF SECTION C. 



For the purpose of examination of the bedded gneisses, the 

 natural sections which have been laid bare in Greenwattle Creek, 

 near Mount Livingstone, are very favourable. It is thus possible 

 not only to make a minute examination of the individual beds, 

 but also of the relations of the beds to each other, and to the 

 neighbouring massive rocks. The results of the examination 

 which I have made, I am now preparing for publication, but I 

 may anticipate the work by mentioning the principal results 

 arrived at. 



The schistose rocks vary a good deal in character. Some can 

 be best described as granite-gneiss, using the term merely in a 

 structural sense. Others have a distinctly bedded appearance, 

 dipping generally south-westward at a high angle. These have a 

 distinctly gneissic structure, being composed of foliations of biotite 

 felspar, and quartz. Other beds are augen gneiss, and finally 

 there are others which can be classed only as mica-schist. 



In texture these gneisses vary from crystalline granular com- 

 pounds of felspar, biotite, and quartz, with only traces of 

 parallelism in the minerals, to completely foliated beds of felspar, 

 biotite, and quartz, or of mica and quartz only, thus forming a 

 mica-schist. 



An examination of a number of thin sections of these rocks 

 prepared across the foliation, reveals their character as being 

 entirely diiferent to any of the other metamorphic schists which 

 I have described, eitlier of the phyllites or mica-schists. Of 

 course it is also the case that they have no resemblance to the 

 contact-schists properly so called. The felspathic and quartzose 

 foliations are formed of broken and abraded felspars and quartz 

 grains. Some of the felspars show signs of stretching, and the 

 quartz has a cloudy obscuration indicative of strain. 



The filling-in of the foliations is. by the detritus from the 

 abraded and broken minerals, together with more or less secondary 

 quartz, which has, together with mica, acted as a cement. The 

 micaceous foliations in these gneisses are of secondary oi'igin, 

 being derived by regeneration from the crushed and abraded 

 portions of the rock. No doubt these ai^e portions of the mica 

 forming the foliations or associated with the felspars and quartz, 

 which, in a fragmentary condition I'epresents the dark coloured 

 biotite of the original constitution of the rock, but the micaceous 

 foliations as a whole are tlie result of regeneration of the detrital 

 materials. 



It may be said, speaking generally, that the more the rock 

 shows evidence of crushing, squeezing and comminution, the 

 smaller are the rounded grains of felspar, and the more numerous 

 are the micaceous bands. Thus, I found that the bands w Inch had 

 most the appearance of mica-schist were rocks of the above- 

 mentioned kind, in which the original sti^ucture had been completing 

 obliterated, the result being foliations of biotite separated by 



