FROM THE MAINLAND OF SOUTH VICTORIA LAND 219 



Another specimen from the same locality contains a cavity occupied by calcite. 

 The walls of the cavity are quartz and felspar in drusy relief. The felspar is much 

 altered, so much so that, in the case of some squarish sections occupied by secondary 

 minerals, it is not certain that they may not have been nephelines. In all these rocks 

 no stainable products were discovered, and therefore this suggestion of nepheline 

 cannot bear much weight. 



Aplitic granite porphyries, both pink and grey, are met with in the Ferrar Glacier 

 collection. These are notably from the moraines of the East Fork of the Ferrar Glacier 

 and elsewhere in the neighbourhood of the Kukri Hills. 



THE APLITES 



As already stated the aplitic granite porphyries are a transition stage between the 

 hypidiomorphic -granular granite and the panidiomorphic fine-granular aplite. Between 

 the aplitic granite prophyries and the true aplites are porphyritic aplites of the 

 alsbachite type. In the typical aplites the chief components are orthoclase and quartz, 

 and the texture expresses eutectic composition. Numerous specimens were found as 

 erratics in the vicinity of the granite outcrops. Of these the following two from Cape 

 Irizar are worthy of description. One of these is of an almost white colour relieved 

 by black specks of biotite. Small porphyritic crystals of anorthoclase are studded 

 sparingly through the finer grained base. Under the microscope the base is seen to be 

 granular and poikilitic patches are frequent. The quartz grains are surrounded by 

 orthoclase arranged with great regularity. The biotite shows light yellowish and 

 greenish tints. 



The other example is of a light pink colour. The texture is very fine and even. 

 Under the microscope (Fig. 9, Plate III) small porphyritic oligoclase crystals appear at 

 intervals and are invariably surrounded by radial -graphic quartz and orthoclase. The 

 remainder of the section consists of granular quartz and orthoclase with occasional but 

 rare porphyritic orthoclases of a late period of crystallisation. Ferromagnesian minerals 

 are almost absent. Grains of ilmenite, and rarely small yellowish grains appearing to 

 be epidote are present. 



In this rock, obviously, a sprinkling of small plagioclase crystals was the first act 

 in crystallisation. 



THE PEGMATITES 



Pegmatite veins in connection with the pink granite appear to be of rare occurrence 

 for none were met with in situ. Examples of coarse pegmatites occur amongst our 

 collections of erratics. 



Ferrar mentions quartzose, felspathic, and micaceous veins in the grey granites of 

 the McMurdo Sound region. Priestley's collection also contains coarse pegmatitic 

 granite and vein quartz. In some cases these are to be seen traversing a grey 

 granite. 



The outcrops of the gneiss and schist series are never free from pegmatite veins, 

 and undoubtedly the majority of the erratic specimens are derived therefrom. Such 

 a one is a coarse quartz-microcline rock from the Stranded Moraines ; this also carries 

 some muscovite and frequent pink garnets, the latter up to 3 mm. diameter. 



The gneiss at Cape Roberts is rich in coarse-crystallised veins, usually quartz and 

 felspar, at other times quartz, felspar, and biotite. Amongst these, felspars 23 cm. in 

 length and much graphic quartz and orthoclase were noted. 



At Cape Bernacchi, and at Marble Point several miles to the north of the latter, an 

 ancient sedimentary series, conspicuous amongst the members of which is a thick 

 marble formation, is crossed by pegmatitic formations. Amongst these is a quartz- 



II 2 i 



