12 
II. T. FERRAR. 
sulphur was found scattered over their surfaces. They rise 50 to 100 feet above the 
ice, and consist of black hornblende-basalt and olivine-basalt (382-386, see p. 103) 
which have apparently filled up volcanic necks now undergoing rapid denudation. 
The sulphur (379) is found thickly distributed over the surface of the frost-riven rock 
and is sometimes in quite perfect crystals. 
Castle Rock (Fig. 4), 3 miles distant from Winter Quarters, rises to a height of 
1400 feet as a bold crag. It is surrounded by vertical cliffs 400 feet high. On the 
south the foot of the crag is snow-covered, but on the north the land falls sheer away 
for 1000 feet. On the east and west sides black basalt can be seen forming the lower 
part of the crag, which consists above entirely of palagonite-tuff (380). The tuff 
varies much in texture ; sometimes it consists of yellow and black angular fragments 
of olivine-basalt and basalt-glass half an inch across and very uniform in size ; in 
other places the black masses attain as much as a foot in diameter ; sometimes they 
are almost circular in section, and are often arranged in parallel rows. The summit 
of the rock is flat and strewn with loose black fragments of olivine -basalt (319), 
more than two inches in diameter and very uniform in shape and size. About a 
mile to the northward of this rock occurs another crag consisting of tuff quite like 
the former and possibly of similar age. 
Crater Hill. Along the south-east side of the peninsula there are three 
scoria- craters. Two of these are rather insignificant, but the third, Crater Hill, 
rises to a height of over 1000 feet, and the crater-lip at its summit is almost perfect. 
On the north side the lip rises about 200 feet above the bottom of the crater, but on 
the south side it has been broken down. The rocks obtained from this hill include 
black vesicular basalt (341) and red scoriaceous basalt-glass : the latter has obviously 
flowed over the lip of the crater and now forms the highest point of the hill. Near 
the south foot of Crater Hill, porphyritic olivine-basalts (656 and 659, see pp. 105-6) 
rise sheer out of the sea and form a cliff. They appear to extend as horizontal sheets 
right under both Crater and Observation Hills. 
The Harbour Heights , or Ay-rival Day Heights, as they have been sometimes 
called, include the three prominent eminences between Castle Rock and Hut Point 
They rise over 100 feet above the general level of the snow-covered peninsula. 
Numerous vesicular olivine-basalts (323) and basalt-bombs (367) have recently been 
ejected from these vents, and an occasional flat space, bare of snow, exhibits massive 
but vesicular lava-flows of olivine-basalt (366) (Plate 11). These volcanoes have a 
general resemblance to the Pleistocene* volcanoes of Auckland in New Zealand. 
Between the southernmost crater of the Harbour Heights and Crater Hill there is a 
basin-shaped depression, the vent of another small volcano. Near this depression 
occurs a large rock-mass measuring quite 15 feet across and 12 feet high. This rock 
appears to be the remains of a dyke, and from it the specimens (369-378) were 
taken. It is a limburgite with abundant foreign inclusions. Of these some are of 
* Hutton, Trans. New Zealand Inst. (1899), 1900, vol. xxxii, p. 178. 
