198 
little development of unduiose extinction or production of 
sericite. Quartz grains are dovetailed. Felspars are mostly - 
microcline and orthoclase, the latter kaolinized. Composite 
grains are present, but are difficult to distinguish from granu- 
lated quartz fragments. 
i Mount (ed Cars ad, 
Very similar to vii. Dilference of grain in different bands 
is not so great. Much less mica is present, its place being 
taken by light-coloured interstitial chlorite. 
Spring Greek, Mount Hemarkarbtie, 
Macroscopic character s.—Distinctly banded 
rock, consisting of layers differing in composition and tex- 
ture. Finer grained layers are dark greenish-grey in colour, 
and are composed chiefly of quartz, with a few felspar and 
rock fragments of a pinkish colour. Coarser grained layeis 
are more pink because of the greater abundance in them of 
the coloured constituents above noted. Fracture rather 
round than across the grains, except in the finer bands. 
Microscopic character s-—Consist of rather 
coarse, perfectly rounded grains, set in a finer ground mass 
of the same materials. Mineralogically similar to the type 
rock of Mitcham (i.), but differs in the very much greater 
relative abundance and variety of the composite grains. 
These make up quite 30 per cent. of the rock. Remainder of 
the rock is composed of quartz and felspar in about equal 
abundance. The felspars are similar to those in the Mitchain 
rock (1.), but are all rather decomposed ; some contain a little 
chlorite along the cleavage cracks. No strain structures are 
noticeable in either quartz or felspar. 
The most abundant or remarkable types represented among 
the composite grains are as follows: —- 
1. Rounded grains of reef quartz. 2. Rounded grains 
of quartz rock, whose high degree of ^ internal 
granulation indicates that they were derived from 
crystalline schists. 3. Particles of very fine grained, neariy 
opaque, micaceous slate. 4. Fragments of decomposed holo- 
crystalline, but rather fine-grained, eruptive rock, composed 
of kaolinized felspar, quartz, chlorite, and apatite. 5. A few 
pieces of granophyre, consisting of a mass of minute spheru- 
litic aggregates of quartz and felspar.* А considerable 
amount of interstitial viridite is present and acts as a ce- 
ment. 
* A rock very similar to this occurs as a large erratic in the 
Upper Cretaceous series, near Stuart’s Creek. 
