86 Transactions. 



lites are nearly an inch in diameter at times, and have irregularly 

 curved radiating arms. Rutley regards the objects as a result 

 of refusion of the rhyolite. Sollas rejects this explanation, and 

 states that these features, as well as certain isotropic feldspars, 

 have resulted from processes of decomposition. This explana- 

 tion he afterwards withdrew, but did not substitute another. 



A peculiar type of rock with a semi-brecciated appearance 

 is called by Professor Sollas " wilsonite." He suggests that its 

 peculiar structure is due to the association of fragments of lava 

 ejected during an eruption which retained their viscosity until 

 they reached the ground. 



A very complete bibliography of the literature of Cape Col- 

 ville geology is given in the introduction to Professor Sollas's 

 work.* Unfortunately, it is impossible to represent the results 

 of different authors here. This is less regrettable because they 

 are in essential agreement as to all the main features. Re- 

 ference, however, should be made to the geological map of the 

 district in the second volume, and a similar map by Professor 



Park.f 



In the second volume of Professor Sollas's report there are 

 descriptions of rocks collected by McKay on the western spurs 

 of the Kaimanawa Range. J Some of these are probably material 

 ejected by Ruapehu and its neighbours, for the rocks agree with 

 those of the volcanoes in all essential particulars. Others agree 

 with rocks near Lake Taupo. Other descriptions are given of 

 rocks from the Sugarloaves, Taranaki. The only special feature 

 to notice is the occurrence of hypersthenej in one example as a 

 core of a hornblende crystal. 



Fox,§ in a paper on the volcanic rocks near Auckland, has 

 described certain tuff-beds as being formed of fragmentary matter 

 ejected by the Cape Colville eruptions, and others as formed 

 during the eruptions of the Waitakerei volcanoes. 



The physiography of this region has been referred to by 

 many authors. Hill, in particular, and Park have described 

 the physiography of the Ruapehu region, and further descrip- 

 tions have been added by Von Friedlander,|| who visited the 

 district after the eruption of Te Mari in 1896. Marshall and 

 Alison have also written on the subject in the volumes of the 

 " New Zealand Alpine Journal." Thomas, in papers quoted 

 above, has dealt fully with Tongariro. An accurate map of 

 Tongariro has been drawn by Cussen. 



* Sollas, " Rocks of Cape Colville Peninsula," vol. i, p. 124. 

 |- Park, " Geology and Veins <>f Hauraki Goldnelds, N.Z. Inst. Min. 

 Eng., I HOT. 



I Solhis, " Rocks of Cape Colville Peninsula," vol. ii, pp. l(>0-65. 

 § Fox, Trans. N.Z. Inst., vol. xxxiii. p. 462 ct ••>"/ 

 || Friodlander, Trans. N.Z. Inst., vol. xxxi. p. 4'.ts. 



