128 
G. T. PRIOR. 
Calculation of the “ norm ” gave the following result : — 
KAlSi 3 0 8 
= . 
8-90 
NaAlSijOg 
= 
2G-72 
CaALSiA 
= 
32-25 
SiO., 
= 
3-48 
CaSi0 3 
= 
2-55 
FeSiO s 
= 
10-03 
MgSi0 3 
= 
9-40 
FeO. FeA 
= 
2-09 
FeO. TiO„ 
= 
3-04 
Ca 3 2P0 4 
= 
0-93 
In the American quantitative system the rock would be classed as Ilessose. 
Blue Glacier. — Of somewhat similar character to the rock of the “ tongue ” are 
the dyke-rocks (572-574) collected by Dr. Koettlitz half-way down' the Blue Glacier. 
One of these, in which the hornblende occurs in large ophitic plates, is almost 
identical with the rock of the “ tongue,” but the others are less coarse-grained, and 
show more numerous and better crystallised phenocrysts of hornblende. In this 
respect they resemble camptonitic rocks from Montreal, but are of coarser grain and 
approach to essexites. Under the microscope (Plate IX, Fig. 3), they show long, 
prismatic crystals of hornblende in large amount, with interstitial plates of altered 
felspar ; hexagonal sections of apatite are very plentiful, while grains of magnetite and 
ilmenite occur very sparingly. The hornblende is similar to that in the “ tongue ” 
with pleochroism : a = brownish-yellow, /3 and y = deep reddish-brown, and extinction 
as high as 15° ; most of the sections show a dark-green margin. 
Kukri Hills. — The specimens (G99, 700) from the Kukri Hills, illustrating the 
intrusion of granite into dolerite (see p. 36), show pink granite in contact with and 
almost surrounding fragments of a dark-gray rock. Under the microscope the latter 
is seen to consist of felspar, in interlocking grains and indistinct prisms, with shreds 
and irregular patches of green hornblende and a little quartz. Accessory constituents 
are one or two small crystals of sphene and a few shreds of chlorite enclosing magnetite. 
The hornblende shows pleochroism : a = pale yellowish-brown, (3 = dark greenish- 
brown, y = dull green. If this rock, therefore, represents a dolex-ite like those 
described in a later section (p. 136), it has suffered as extreme a metamorphism as 
some of the old dolerites of Cornwall. 
Amongst the pebbles from the dredge off King Edward VII Land are horn- 
blende-biotite -granites and gneisses, and diorites with large ophitic plates of hornblende. 
One pebble of coarse-grained biotite-granite differs from the others in containing 
large crystals of microcline. 
A boulder of hornblende-biotite-granite from the 500-ft. slope on Mount Terror 
deserves mention owing to the peculiar character of the biotite, which occurs in small 
thick crystals standing out conspicuously from the white ground-mass. 
