90 
Rex T. Pkider. 
while possible to distinguish between the upj)ermost horizon and the bands 
in the lower part of the series, these low er members could not l^e distinguished 
from one another. 
In this paper, therefore, the cpiartzites will be considered in two main 
groups — 
(u) The u]jper (piartzit(' (Xo, 5 fpiartzite of the earlie?' paper). 
(6) The lower quartzite horizons. 
(u) The Upper Quartzite is characttalsed by the mode of occurrence of 
ehrome muscovite and almost complete absen(*e of felspar. These rocks are 
all even, coarse-grained types, consisting almost wholly of (juartz, in which 
the average grain size is of the order of 3 mm. diameter, although much 
coarser vaiieties are often encountered. The remarkable evemaess and coarse- 
ness of grain indicate the high degree of metamorphism to which these rocks 
liave been subjected (Harker, 1932, ]>. 97). 
A. Micaceous quartzite. Section ])erpendiculnr to bedding. 
Shows the coai’Se granoblastic structure and parallel oriented 
)‘ods of chrome-inuscovitc. 
B. Micaceous quartzite. Wection ])aranel to bedding showing 
tendency of idioblastic mica to be elongated in a common direc- 
tion ■ direction of lineation seen in hand specimen.) 
Under the microscope' the irregular interlocking cjuartz grains frecpiently 
exhibit a marked elongation in sections cut normal to the bedding. Undulose 
extinction often accompanied by incipient cracking is a common feature. 
Minute dusty inclusions, many of w’hich are gas-liquid inclusions, are alw'ays 
present and appear to be arranged in lines normal to the direction of elongation 
of the grains (figure 3A), These appear to be directions of tension joints 
(“ ac joints”) as described by Fairbairn (1937, p. 89), although this cannot 
be verified until fabric analyses of these rocks are made. 
The presence of abundant chrome muscovite inclusions in the quartz 
grains is the most remarkable feature of the upper quartzites. These are 
all arranged in parallel orientation as .shown in figures 3 (A) and (B). In 
