108 THE VOYAGE OF H.M.S. CHALLENGER. 



which burst upon the western coast. Add to these the extremely rigorous climate, 

 and some idea may be formed of the difficulties opposed to the scientific investigation 

 of a land the climatological conditions of which have justly earned for it the name of 

 " Isle of Desolation." 



In addition to the early geological work of MacCormick and Hooker, already 

 incidentally alluded to, we only possess a very few contributions to the lithological 

 constitution of Kerguelen. The rocks collected by the German expedition have been 

 made the subject of a detailed description by Professor J. Roth. 1 The topography of the 

 peninsula on which the German observatory was erected has been studied by Dr. Th. 

 Studer, 2 and he has given geological details of the rocks described by Professor Roth. 

 Mr. Buchanan 3 published his geological notes, taken during the Challenger's visit, and 

 Mr. Moseley 4 described the natural history of the island. The chapter devoted to 

 Kerguelen in the Narrative of the Cruise 5 may be held as reasonably complete with 

 regard to the fauna and flora of the island, and the geology of those parts visited 

 by the Challenger's staff. 



These notes are specially devoted to the description of the numerous rock-specimens 

 collected by Mr. Buchanan and others at various points in the island. We have also 

 thought it advisable to condense here all the more important statements regarding the 

 geology of Kerguelen scattered through the writings cited above. 



Like most oceanic islands, Kerguelen is essentially of volcanic formation. Sedi- 

 mentary strata, properly so called, are hardly represented at all. The accumulation of 

 erupted material forms, one might almost say, the entire mass of the island. 



Before proceeding to the description of the rocks, we will sketch out those physical 

 features of the island which have a bearing on the facts to be considered. 



The Kerguelen group is composed of 130 large and small islands, and 160 rocks. 

 They are grouped round the central island, and are situated in the centre of the 

 South Indian Ocean, nearly half-way between Africa and Australia, and some hundreds 

 of miles south of the route of the clippers which round the Cape of Good Hope on the 

 Australian passage. Its position is approximately 50° S. and 70° E., thus corresponding 



1 J. Roth, Ueber die Gesteine von Kerguelenland, Monatsber. d. k: preuss. Alcad. d. Wiss. Berlin, 1875, pp. 

 723-735. 



2 Th. Studer, Geologische Beobachtungen aiif Kerguelenland, Zcitsch: d. deulsclt. geol. Gesellsch., 1878, pp. 

 327-350. 



3 J. Y. Buchanan, On Chemical and Geological Work done on board H.M.S. Challenger, Proc. Eoy. Sue, 

 vol. xxiv. pp. 617-622, 1876. 



4 H. N. Moseley, Notes of a Naturalist on the Challenger, pp. 184-215. The author cites several memoirs on the 

 natural history of Kerguelen. 



6 Narr. Chall. Exp., vol. i. pp. 332-360. See also Relation de deux voyages dans les mers australes, par M. de 

 Kerguelen, Paris, 1782; J. C. Ross, Voyage in the Southern and Antarctic Regions, vol. i. chap, iv., 1847; Die 

 Vermessungsarbeiten S.M.S. "Gazelle" an die Kiisten der Kerguelen Inselgruppe (Ann. des Hydrogr. und Marit. 

 Meteor., 1875, pp. 354-365) ; Rev. S. J. Perry, Report on the Meteorology of Kerguelen Island, 1879 ; Account of the 

 Penological, Botanical, and Zoological Collections made in Kergueleu's Land and Rodriguez during the Transit of 

 Venus Expedition, Loudon, 1879, Phil. Trans., vol. clxviii. 



