176 WwW. R. BROWNE. 
by the presence of interbedded quartzites in the form both 
of lenticular patches a few yards long and a few inches 
wide, and of more continuous layers. The prevailing 
quartzose nature of the schists too would tend to indicate 
their derivation from arenaceous sediments. There is a 
notable proportion of what may be termed quartz-schist, 
containing predominant quartz, with a subordinate amount 
of mica: ordinary mica-schist, too, is plentiful, and a mica- 
schist with porphyroblasts of (?) cyanite has been found in 
a few places in close contact with the blue gneiss. A very 
well-defined variation of the schist is really a kind of very 
fine-grained gneiss, according to Van Hise’s definition of the — 
term.’ In hand-specimen a fracture perpendicular to the 
schistosity shows alternate bands of light and dark minerals 
onasmall scale. The dark micaceous layers are about 
"2 mm. thick, the more acid layers ranging between 1°5 and 
2°5 mm. approximately. These rocks seem to be similar in 
origin to the other schists, with which they are intimately 
associated, and from which they cannot be differentiated. 
In many places the schists are interleaved with Cooma 
gneiss which has been subjected to. mechanical deforma- 
tion: the minerals have been broken up and the grainsize 
considerably reduced; in such cases it is often impossible 
to differentiate between a relatively coarse-grained schist 
and the mechanically altered gneiss. 
The planes of schistosity often show much bending and 
puckering; this is rendered very noticeable when, as 
frequently happens, little pegmatite veins have been in- 
jected along these planes. The numerous pegmatite and 
quartz veins which occur throughout the schist generally 
follow the planes of foliation, and quite commonly there 
have been regular lit par lit injections of pegmatite. 
+ A Treatise on Metamorphism, p. 782. 
