108 
G. T. PRIOR. 
A nodule (342) found near the ship, and consisting of pale-green diopside, grains 
of clear olivine and plates of labradorite, showed a few dull-green isotropic grains of 
picotite. In another somewhat similar nodule (478), from below Castle Rock, occurs 
a little hypersthene, showing straight extinction and pleochroism from pale-pink to 
pale-green. 
The nodule (415), which is represented in section in Plate VIII, Fig. 2, was enclosed 
in a hornblende-limburgite from between the Gap and the ship. It consists of a granular 
aggregate of labradorite and pale-green diopside, with smaller grains of altered olivine 
and a little basaltic hornblende. The labradorite shows symmetrical extinctions of 
23°-26°, and encloses numerous gas-bubbles. The olivine grains are red with oxide of 
iron, which is often arranged in bundles of wavy threads crossing each other at right 
angles ; probably these threads were originally of magnetite, like the inclusions in the 
olivine-nodules described below. 
Fig. GO. — Inclusions in Augite op Nodule Fig. 61. — Olivine with Magnetite- 
from Turtle Back Island. inclusions, prom Castle Rock. 
(Magnification, 100 diam.) (Magnification, GO diam.) 
Of the non-felspathic nodules, one (180, from the 900-ft. knoll on Mount Terror) 
consists of olivine, enstatite, and purple titaniferous augite ; another (438, from Harbour 
Heights) almost entirely of clear, colourless olivine and enstatite ; while others are 
composed wholly of olivine impregnated with magnetite. A nodule (or possibly a 
bomb) from the south slope of Turtle Back Island consists mainly of smoky-black 
augite, and shows only a little yellow olivine in bands. Under the microscope the 
augite shows some pleochroism from pale smoky-purple to brownish yellow, and has 
numerous gas and vermiform liquid (?) inclusions arranged in lines ; in one crystal a 
halo of fantastically-shaped inclusions surrounds an included dark rounded grain 
(see Fig. GO). 
Some of the nodules in the basalt near Winter Quarters (375 and 437) are of 
dark ironstone-like appearance. They were found to consist wholly of olivine-grains 
densely impregnated with magnetite, and thus resemble the olivine-phenocrysts in the 
basalt (3GG) from Harbour Heights (see p. 104). Under the microscope one of these 
