486 T Id n xactio n s . 



olivine inclusions as well as slight inclusions of groundmass. Some small 

 and well-formed nepheline, occasionally with central inclusions of ground- 

 mass. Pink-brown aiigitos ; small forms are rare. A fair amount of 

 olivine ; small forms are again rare. Some large grains and crystals of 

 magnetite. Tavo cracks in the rock have been recemented with a clear 

 colourless mineral of very low double refraction. Trachydolerite. Speci- 

 men taken from the end of the jetty in situ. 



Erehus. 3. — Coarse-grained granitic texture, with tendenc)^ to banded 

 structure. The larger feldspars flesh-coloured, the smaller semi-opaque 

 white. Quartz clear. Much black mica. Feldspar slightly clouded, but 

 in places quite clear, practically all striated ; all contains ajiatite. Patches 

 of micro-pegmatite. There are large areas of quartz, which show fairly 

 numerous fluid inclusions with bubbles. A fair amount of dark mica in 

 brown and green shades. Quartz-diorite. From Cape Royds, not in situ. 



Erebus, 4. — Felsitic texture ; granular crystalline ; general shade light 

 indian-red ; some feldspars, all quite small, are a brighter pink. Micro- 

 pegmatite, with patches of clouded red feldspar in tesselated form, and 

 other areas of clear colourless feldspar in similar form ; striation not infre- 

 quent, but somewhat indistinct. One feldspar is clouded in centre, with 

 clear outer zone, surrounded by micro-pegmatite. A somewhat similar 

 case occurs where the centre is of a pale green-grey and jiolarizes differently 

 from margin, although extinguishing with it. Hornblende in blades and 

 irregular forms, olive-brown in parts but mainly green, is scattered rather 

 sparsely through the slide. The larger grains of quartz are not prominent, 

 and contain a few very small fluid inclusions with bubbles. From Cape 

 Royds, not in situ. 



These last tM^o specimens are samples of the numerous blocks of granitic 

 materia] which lie hei'c and appear to present great variety. 



Turtle IsLA^'D. 



Turtle Island was a small pyramidal islet some eight miles from the 

 ship, and the object of rather frequent excursions. It is about" a couple 

 of hundred yards long and little more than half that in diameter, perhaps 

 60 ft. high. On its eastern side were considerable pressure-ridges on the 

 sea ice. At the eastern base the rocks were compact, weathered to 

 simulate stratification, and appeared to be the ordinary olivine basalts 

 of the district, l)ut here the olivine crystals were very large and con- 

 spicuous. The general surface of the islet consisted of very fine rubble, 

 with occasional boulders of kenyte and other volcanic rocks, the crystals 

 from which sparkled in the sun like diamonds, and were rendered con- 

 spicuous for a considerable distance. 



Turtle Island, 1.— Two specimens, one M'ith a l)lack compact base and 

 very elongated rhombs of feldspai'. practically lath-shaped in cross-section ; 

 the other brown-black, rougher and more slaggy base, with well-developed 

 rhombs of feldspar. The first shows parallel structiu'e, the second does 

 not. Trachydolerite and kenyte. These specimens were from boulders. 



Turtle Island, 2.— Dark-grey, compact trachytic, with large vesicles, 

 up to 13 mm. diameter. Cleaves easily in slabs of irregular form from 

 5 mm. to 10 mm. thick. Groundmass light purple-brown augite and plagio- 

 clase feldspar in wisps and rods, with a little olivine and considerable 

 quantity of magnetite. The sole porphyritic constituent is feldspar in very 

 irregular forms. Trachyte. 



