726 SUBANTARCTIC ISLANDS OF NEW ZEALAND. [Physiography, Geology. 



deposit, though the former seems more likely. It is full of rounded pebbles of granite 

 and trachyte like that in position at Musgrave Peninsula, of gabbro, and of various 

 gneisses and schists. The latter are at times contorted, and with well - marked 

 schistose structure. There are granites of a different type from that at Musgrave 

 Peninsula, but they are nearly all biotite- granites, with small flakes of muscovite 

 occasionally visible in some slides ; no specimen like the Snares granite was dis- 

 covered. The gneisses contain little feldspar, and under the microscope do not 

 show marked schistose structure, being of a granular type. The trachyte occurs 

 occasionally in large boulders, one being over 2 ft. in diameter. The conglomerate 

 is penetrated by the same dykes that penetrate the overlying basalts, one being 

 exactly similar to a dyke of camptonitic type occurring on the opposite shore of 

 Adams Island. These facts show that the conglomerate was formed subsequently 

 to the gabbros, granites, or trachytes, but earlier than the basaltic flows. No 

 pebbles of diabases or porphyrites were found ; but this does not say that they do 

 not occur, as only one morning was spent in examining the locality. The most 

 noteworthy fact about the conglomerate is that its contents prove absolutely the 

 proximity of a continental area at a time immediately anterior to the outbreak of 

 volcanic action. In what direction this land lay is at present undetermined, but 

 it is possible that the granite rocks at the Snares and Bounties are remnants of 

 the area which supplied the pebbles to this conglomerate. The presence of con- 

 torted schists is especially important, as these show the probable presence of an 

 area of metamorphosed sedimentary rocks. No traces of any fossil remains were • 

 discovered to help to fix its age. 



At the extreme end of Musgrave Peninsula a large mass which has been included 

 in the basaltic rocks and brought up from below shows a mixture of fragments evi- 

 dently derived from a granite area. This is apparently a tuff containing fragments 

 of quartz, orthoclase, and plagioclase feldspars, and occasional fragments showing 

 distinct granophyric structure. 



(4.) The Older Basic Series. 



The basic rocks in this area are divided in all probability into an older and a 

 younger series. The older is best developed at Musgrave Peninsula, on the east 

 side of Carnley Harbour. This peninsula is about a mile in length, and half a mile 

 wide at its broadest part. A rapid examination was made at various points of the 

 shore-line, and the peninsula was traversed from one end to the other, but no rock 

 was seen outcropping on the top, owing to the complete covering of peat and scrub. 

 The whole peninsula is apparently composed of basic rocks, with the occasional 

 exception of rocks of more acid type, and is built up on the foundation of granite 

 and trachyte which is exposed near the isthmus. The general dip of the beds is 

 towards the south, but there may be alterations which were not noticed. Although 

 it is built up principally of flows, dykes of a similar type are extremely frequent, 

 and it is at times very difficult to tell the dykes from the flows, especially as some 

 of the latter are very coarse in texture. Bocks which evidently belong to this series 

 occur at Disappointment Island, and it is extremely likely that they occur on the 

 west side of North Arm, on Circular Head Peninsula, and on the spur terminated 

 by McClure Head, as fragments of porphyrites were picked up in the latter locality, 

 although the rock was never seen in position. It is possible, therefore, that an 



