BY VV. G. WOOLNOUGH. 501 



one which does appear was made by Mr. D. Mawson, B.E., and 

 Mr. Stoddard at the Sydney University, by kind permission of 

 Professor Liversidge, and with the assistance of Mr. Schofield, 

 A. R.S.M., F.C.S., and to all these gentlemen my best thanks are 

 due and are hereby gratefully rendered. 



Throughout the greater part of the investigation I have been 

 hampered by lack of a suitable microscope and accessory apparatus, 

 as the laboratory of the University of Adelaide is only in its 

 infancy. This and the fact that illness and the great 

 amount of routine work in arranging the curriculum in what is 

 practically a new course at the above University have made great 

 demands upon my time, must be my excuse for any gaps which 

 occur in the work. I trust that those which do occur will not 

 seriously interfere with the accuracy or completeness of the 

 description.^. 



Granite (Narokorokoyaw^a). Plate xxxv., fig. 1. 



Macroscopic characters. — Specific gravity 2 '6 6. The rock is 

 moderately coarse in grain, and consists of a holocrystalline mass 

 of clear quartz, milky-w^iite striated felspar, black biotite, and 

 dull black grains of hornblende, with a little magnetite here and 

 there. 



As a whole the rock has undergone a considerable amount' of 

 alteration, both from crushing and from chemical change. It 

 was very difficult to obtain material sufficiently undecomposed 

 for the preparation of thin sections, even though a considerable 

 amount of blasting has been done in the making of a road. 



The mechanical strain to which the rock mass has been sub- 

 jected is expressed by the strong development of cleavage planes, 

 etc. In the field an obscure foliation is apparent, but it is not 

 at all marked in hand specimens. 



Microscopic characters. — In thin section the rock is seen to 

 possess a typical hypidiomorphic granular texture of rather coarse 

 grain. The pressure to which the rock has been subjected is 

 expressed microscopically by the shattering of the component 

 minerals, and by the development of optical anomalies. These 



