SUMMARY. 
139 
(from 2 to 3 mm. in diameter) rounded red patches of granitic material fairly uniformly 
distributed through it. Under the microscope (Plate X, Fig. 6) the main mass of the 
rock is seen to consist of small purple sub-ophitic augites, felspar-laths, magnetite-rods, 
and green pseudomorphous hornblende. The red patches are composed of stout red 
and kaolinised felspar-prisms, with a little interstitial quartz and a few shreds of biotite. 
Of interest in connection with the wide extension of the dolerite-sandstone 
formation (see p. 53) is the fact that amongst the pebbles dredged up off Cape 
Wadworth, and also to the south of the Balleny Islands, are some of dolerite like that 
of the Ferrar Glacier, and showing similar spherulitic and micropegmatitic patches. 
Further, a pebble (866) from the dredge south of the Balleny Islands shows characters 
almost precisely similar to the “ chilled ” dolerite (687) from Inland Forts at the 
junction of dolerite and sandstone. 
The dolerite fragments found in moraines on Mount Terror are similar to the 
dolerites of the mainland ; some are very coarse-grained and gabbro-like, with coarse- 
grained micropegmatite, as in the specimens from Depot Nunatak described above. 
In a moraine off White Island was found a fragment (307) of typical olivine- 
gabbro. Under the microscope it shows broad plates of labradorite with glomero- 
porphyritic groups of pale yellowish-brown diallage in large irregular plates and small 
olivines in ter grown with the diallage. 
In connection with the dolerites, a peculiar conglomerate found on the west 
promontory of Black Island deserves mention. It consists mainly of rounded grains of 
quartz and a little felspar (including microcline), cemented by calcite ; but it also 
contains numerous fragments of dolerite, similar to that of the mainland. 
SUMMARY. 
The basement-rocks of South Victoria Land consist of crystalline limestones, 
gneisses and granites. 
The crystalline limestones are remarkably free from accessory constituents, but 
some contain chondrodite. 
The gneisses are metamorphosed granites (orthogneiss) and are often characterised 
by prominent augen-structure and by cataclastic effects. 
Above the gneisses occur masses of red and gray granites which pass occasionally 
into more basic diorites or hornblende-gabbros. 
Intrusive in these basement-rocks are dykes, chiefly of lamprophyric rocks 
including camptonites and kersantites, but comprising also quartz-porphyries and 
rocks chemically allied to banakite. 
Upon the granite has been deposited an extensive sandstone-formation in which 
some obscure charred plant-remains have been found. 
Through the sandstones have been intruded very widespread sills and dykes of 
dolerite. This dolerite is very uniform in mineral-composition throughout wide areas, 
T 2 
