396 PROCEEDINGS OF SECTION C. 



DESCRIPTIONS OF PHOTO-MICROGRAPHS OF SECTIONS OF ROCKS 

 FROM NEAR STATION PEAK, YOU YANGS. 



Plate I. 



Figure I. — No. 393. Granite of Station Peak X 13 diams. + 

 Nicols. — On the upper left-hand side a large crystal of alkali felspar, 

 possibly soda orthoclase, shows very fine lamellation. A small quantity 

 of albite is intergrown with it. Just above the centre of the field is a 

 porphyritic crystal of plagioclase showing albite twin-lameFsB. The 

 lower left-hand side consists of biotite and quartz in a position of 

 extinction, and the lower right-hand side consists of a big quartz 

 crystal showing strain polarisation effects. 



Figure II. — No. 361. Segregation in Granite, summit of Station 

 Peak, X 24 diams. + Nicols. — A large rather embayed strained quartz 

 crystal occupies the lower left-hand side of the figure. A porphyritic 

 plagioclase occurs in the lower right-hand side, and the rest of the 

 field consists of quartz and alkali felspars, with well-defined biotite 

 crystals and a few sections of hornblende. 



Plate II. 



Figure I. — No. 390. Segregation in Granite, south-west flank of 

 Station Peak. X 24 diams. + Nicols. — The figure shows a well-defined 

 panidiomorphic structure. The minerals are mainly biotite and felspars, 

 both plagioclase and an alkali felspar being represented. Only a little 

 interstitial quartz is present. 



Figure II. — No. J. Dyke in Granite, south-east slope of Station 

 Peak, X 24 diams. + Nicols. — Most of the field consists of idiomorphie 

 zoned crystals of plagioclase, some showing both albite and Carlsbad 

 types of twinning. Hornblende and biotite altering to chlorite are also 

 to be seen, and uralite also occurs. 



Plate III. 



Figure I. — No. 354. Metamorphic Rock, altered Ordovician (?), 

 south-west corner of Station Peak, X 24 diams., ordinary light. — The 

 sediment has been completely recrystallised. The dark areas are 

 mainly tourmaline, with some biotite. The light areas are secondary 

 quartz, with white mica, which may be bleached biotite. 



Figure II. — No. 387. Metamorphic Rock at contact with Granite, 

 south-west corner of Station Peak, X 24 diams, ordinary light. — Very 

 little tourmahne is shown in this slice. The dark areas are brown-green 

 crystals of biotite. The light areas are partly quartz, but mainly white 

 mica intimately associated with the biotite. 



6.-THE ASSOCIATION OF LAMINATED CLAYS, SHALES, 

 AND SLATES WITH GLACIAL DEPOSITS: THEIR 

 SIGNIFICANCE AND CHRONOLOGICAL VALUE. 



Bij D. MAWSON, B.E., B.Sc. 



