322 Southern Cross. 



collected by Mr. Bernacchi and Lieutenant Colbeck, and kindly 

 placed at my disposal for the purpose : — 



(1) Cape Adare (iilateau, 900 feet above sea-level) grauitic and 



felsitic boulders, lioriiblende-basalts, and phouolitic trachytes. 



(2) Duke of York Island, Robertson Bay pale green siliceous slate 



containing patches of iron ]iyrites nnd traversed by quartz veins. 



(3) Geikie Land, Robertson Bay pale green slates and quartz-grits 



and hornblende-granite (probably a boulder). 



(4) Protection Cove, near Cape Cod, Robertson Bay amygdaloidal 



basalts and tufl's. 



(5) Possession Island large boulder of haplite containing garnets 



and tourmaline, hornblende-basalts. 



(6) Franklin Island magma-basalt (limburgite) containing large 



olivine-nodules. 



(7) Coulniau Island hornblende-basalts and basalt-agglomerate. 



(8) Newnes Land (foot of Mt. Melbourne) basalt-scoria and also 



(according to specimens collected by Lt. Colbeck) kenyte-like rocks.' 



(9) Foot of Mt. Terror '. hornblende-basalts. 



For purposes of description the specimens will be arranged under 

 species, beginning with what are presumed to be ancient Archaean 

 and Pala?ozoic rocks, viz., the granites, felsites and slates, followed 

 by the basalts and phonolitic rocks, which appear to have been 

 erupted through them, most probably in comparatively recent 

 seolosical times. 



GRANITES. 



Many of the boulders found on the plateau of Cape Adare are of 

 gray and pink medium to coarse-grained biotite granites, biotite- 

 muscovite granite, and biotite-hornblende granites. They were 

 doubtless brought down by the ice from the interior, and the parent 

 rocks, with gneisses and schists,^ probably constitute the basement- 

 rocks of Victoria Land. 



The most remarkable of the specimens is a large mass of very 

 coarse-grained biotite granite, with extremely large Carlsbad twins of 

 felspar (up to 2 in. long by J in. broad), which constitute the main 

 bulk of the rock. The felspars of this rock consist partly of 

 orthoclase (extinction on cleavage flakes were, c (001), straight ; 

 h (010), 6°), and partly of oligoclase, with symmetrical extinction 

 of 12° in twin lamelhe. 



Another specimen of porphyritic granite is less coarse-grained. 

 It is a biotite granite, somewhat resembling the well-known granite 



' According to Mr. Bernacchi, slate is also found at the foot of Mt, Melbourne. 

 ^ A mica-schist in Mr. Borcligrevink's previous collection is described in Proc. 

 Roy. Soc. N.S.W., XXIX., p. 481, 1895. 



