Worth. — Petrological Notes on South Victoria hand Rocks. 483 



Tho following rocks are either not dealt with in the official report, except 

 perhaps in some instances macroscopically, or show variations in the slides 

 MOW i^repared and examined. The details as to locality and general ac- 

 counts of occurrences are furnished by Mr. Hodgson. 



Casllc Rod: — I, camptonite in so far as it contains ainygdaloids of 

 analcimo. 



TenninalioH Rock. — 3. tracliyte. 



Sultan's Head.— 3, pumice. 



Erebus. — 1, trachydolerite ; 3, diorite ; 4, felsite. 



Twile Island. — 2, trachyte ; 5, augite nodule without oHvine. 



Inacccssihk Island. — 1, augite-andesite ; 2. phonolitic trachyte, uii- 

 described in detail ; 3, trachyte. 



Black Island. — 1, diorite ; 3, quartz-felsite ; 4, sandstone ; 5, quait2- 

 ite ; 6, camptonite ; 7, augite-diorite ; 8, camptonite ; 9, micro-pegmatite ; 

 11, augite-diorite ; 13, 14, altered sedimentary, here described in detail ; 16. 



Brown Island. — 2, basalt ; 3, andesite ; 4, basalt. 



Western Mountains. — 1, mica-schist; 2, dioritic lamprophyre ; 6, tulf. 



Granite Harbour. — 1, felsite ; 2, quartz-diorite ; 5, quai'tz-mica-diorite. 



In some instances a description of the rock has been given, but no 

 specific or varietal name applied. Such omission is j^robably unimportant 

 in any event, and must be taken as indicating that analysis as well as 

 microscopic examination might be desired. 



Observation Hill 



Dark -grey trachytic rock, with phenocrysts of augite up to 3 nun. and 

 of olivine up to 4 mm. in length. It is slightly vesicular. Groundmass 

 microlites of brown augite, of olivine-feldspar in lath shape, and magnetite. 

 Larger augites are of a somewhat lighter shade, and show zonal structure 

 between crossed nicols. Larger olivines are numerous, and very uniformly 

 distributed. Fibrous isotropic patches occur, which may be analcime. 

 Beyond a few larger laths, the porphyritic feldspar is confined to one crystal 

 in which a band of inclusions marks out a rhomb. 



C'ASTLE Rock. 



Castle Rock is a mass of reddish breccia, and rises to a height of about 

 400 ft. above the general level of the Ridgeway. It gives one the impres- 

 sion of being the solidified pipe of a vanished volcano. Between the rock 

 and the shore, but at a considerably lower altitude, were several small 

 cones extending over an area something like 300 yards towards the ship. 

 All the specimens taken came from one or other of these cones, and were 

 obviously in situ, though taken from detached fragments. 



Castle Rod; 1. — Dark-gvey, minutely granular I'ock. Enstatite, brown 

 mica, feldspar in broad laths and irregular patches, uniformly clouded. 

 Camptonite. From small cone below Castle Rock, nearest to ship, in situ. 



Castle Rode, 2. — Black basalt, in part highly vesicular, in part compact. 

 No visible olivine. This rock, with Castle Rock, is typical of this area : 

 both are from the same cone. 



Castle Rod; 3. — Very dark-grey rock, shghtly vesicular, with zeolitic 

 amygdaloids. minutely crystalline texture. Groundmass, feldspar laths, 

 minute pale-brown augite, olivine, and magnetite. Larger forms of olivine 

 and augite, frequently with good outline. The z(^olite filling the vesicles is 



16* 



