536 THE GEOLOGY OF NEWBRIDGE, NEAR BATHURST, N.S.W., 



of Reedy Creek towards the Dry Diggings for some distance (see- 

 Map of the Distribution of the Slates, fig. 4). 



Microscopically, it is very fine-grained, consisting chiefly of 

 quartz, some of which shows strain-structure. It is generally all 

 of one size, though certain bands of coarser grain run through 



Distribution of 

 SLATES 



Fig. 4.— Sketch map showing the distribution of the various kinds of slate. 



the rock. Some of the quartzes contain liquid inclusions. The 

 effects of rock-flowage, as described by Van Hise,* are frequently 

 very marked. Biotite runs through the slide, segregated into 

 bands which are nearly parallel, the direction being that of the 

 cleavage of the slate. Some of the bands are wavy, in which 

 case the quartz grains on the convex side are smaller than those 

 on the concave. The biotite is generally brown, highly pleochroic, 

 and birefringent, though the process of chloritisation, which has 

 just started, renders these properties less marked. The biotite 

 crystals are oriented parallel to the slaty cleavage. In the bands 

 of biotite there is also a little carbonaceous matter, and probably 

 some magnetite. A few grains of andalusite occur, which are 



* 'Treatise on Metamorphism." Monograph xlvii. U. S. Geol. Suiv. 

 Chap, viii., p. 748. 



