Art. XV. — A Contribution to tlie Fetrolo;ji/ of Kerguelen 

 Island. 



By EVELYN G. HOGG, M.A. 



[Eead 8th December, 1898.] 



The rocks described in the following paper- were collected by 

 Mr. Robert Hall of Surrey Hills, Melbourne, who visited 

 Kerguelen Island in a whaling vessel in January, 1898. They 

 were obtained from four localities, namely, Howe Island, Green- 

 land Harbour, Royal Sound, and "Cat's Ears." Rocks from the 

 three first-named places have been described either by Professor 

 J. Roth,^ or by Professor A. Renard.^ Under these circum- 

 stances only brief references will be made to rocks and localities 

 which have been previously dealt with. Though no information 

 can be given by the writer as to the field relations of the rocks 

 described below, the specimens brought by Mr. Hall may help to 

 supplement the lengthy account of the petrology of Kerguelen 

 Island given by Professors Roth and Renard. 



Ho7ve Island. Two rocks — a basalt and a phonolite — were 

 taken from this Island. The basalt is bluish-black in colour, and 

 very fine-grained in texture, olivine is the only mineral which can 

 be detected by the naked eye. Under the microscope the slide 

 appears almost entirely opaque owing to the dissemination of 

 magnetite dust through the matrix. Plagioclase felspar, micro- 

 liths of felspar, augite and olivine — the last-named often much 

 serpentinized — can be observed. 



The occurrence of phonolite on this island does not appear to 

 have been previously noticed. On the weathered surface of the 

 specimen crystals of felspar and augite stand out ; the rock 

 breaks with a somewhat even fracture, and felspar and augite 

 are plainly seen embedded in a dark grey matrix of fine-grained 

 texture. The base is micro-granular, composed of grains and 



1 J. Roth. Uebei- die Gesteine von Kergueland. Monatsber. d.k. preuss. Akad. d. 

 Wiss. Berlin. 1875, pp. 723-735. 



2 A. Renard. The Rocks of Kerguelen Island. Narr. C'hall. Exp., vol. ii., pp. 107-141. 



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