ELEPHANT AND CLARENCE GROUP 77 



as the bedding is uniform, but some of the darker rocks may be bedded lavas. [Mr Ferguson was in 

 error here as shown by Prof. Tilley's observations on the Quest Expedition collection — see below.] . . . 

 Much of the island appears to be formed of stratified sediments. Along the extreme west coast, and 

 some eight to ten miles out to sea, is a series of sea-worn hummocks, roughly banded, with smooth 

 slopes, which resemble dark-coloured, table-topped lavas.' [Seal Islands?] 



The first landing by a geologist on Elephant Island was made by J. M. Wordie in 1914 as a member 

 of the party marooned on the island during Sir E. Shackleton's Antarctic Expedition, 1914-17. 

 Although living under very difficult conditions Mr Wordie made rock collections at Cape Valentine, 

 the north-eastern point of the island, and at Cape Wild, 6 miles farther west, which were described 

 by the present writer in a section of Mr Wordie 's account of the geology.^ 



The rocks of the north-east coast consist of dark grey, indigo blue, bluish green and grey-green 

 phyllites of fine texture and glossy cleavage surfaces. Many of them are profusely veined and permeated 

 with secondary silica. The rocks consist of quartz, feldspar (plagioclase), chlorite of three varieties, 

 calcite, and opaque greyish (sericitic?) and black (carbonaceous) matter. The calcite is always, the 

 quartz' frequently, of secondary origin. These minerals are arranged in thin, elongated, parallel lenses 

 representing a small-scale flaser texture indicative of intense pressure metamorphism. These puzzling 

 rocks are difficult to interpret; some may represent ordinary argillaceous sediments, as Tilley believes 

 from a study of the similar rocks of Minstrel Bay on the west coast (see below), but others may have 

 been fine washes from an andesitic terrain, or even andesitic dusts. 



These rocks are highly folded and tilted. At Cape Valentine Mr Wordie states that they dip south 

 by east at about 30°. South of Cape Valentine the rocks dip uniformly to the south and show no 

 folding. Between Cape Valentine and Cape Wild the dip is to the north and changes rapidly from 

 verticality to between 30 and 40°. At Cape Wild the dip of foliation is about 60° towards N. 15° W. 

 At the foot of Mt Houlder (south of Cape Wild) the most striking feature of the section is a reduplica- 

 tion of the beds by 'concertina' folding. There are thus indications of folding on both a small and 

 large scale; small-scale folding and foliation were probably contemporaneous, but the large-scale 

 folding was probably due to a later set of movements. 



The Shackleton-Rowett Quest Expedition (192 1-2) landed parties at Lookout Harbour at the 

 extreme south of Elephant Island and at Minstrel Bay on the west coast. Rock collections made by 

 Mr G. V. Douglas- have been described by Prof. C. E. Tilley .» 



Tilley describes the rocks from Minstrel Bay as dark grey to leaden grey phyllites, much contorted 

 and penetrated by numerous veins of secondary silica. The constituents are essentially quartz and 

 albitic feldspar, with scales and closely packed films of chlorite and white mica, abundant carbonaceous 

 matter and some granules of epidote. These rocks are regarded as normal sediments, and Tilley thinks 

 there is no reason to believe that volcanic material enters into their composition. These phyllites are 

 correlated with those of the Cape Wild area described by me (above). On G. V. Douglas's map 

 (Tilley p 56) signs indicate that the phyllites strike a little south of east and are vertical. Since 

 these phyllites have been found at Minstrel Bay, and in the area between Cape Wild and Cape 

 Valentine, it may be conjectured that the northern coast and perhaps the northern halt of the island 

 consists of these rocks. 



1 J. M. Wordie, 'Shackleton Antarctic Expedition, 1914-1?: Geological Observations in the Weddell Sea Area', Trans. 



""T'Grolfgtl Re^uUs of?hrShL7e:n:Rowett (Quest) ExpedU.on (Report of lecture)', Quart. Jourr.. Geol. Soc. .xxix, 



''3Vp?t;ogra;hicaTNo;:fon Rocks from Elephant Island, South Shetlands', Quest Expedition Report, British Museum 

 (Natural History), London, 1930, pp. 55-62. ^ 



