Wellington Philosophical Society. lib 



After sketcliing rapidly the geology of the district, he proceeded to 

 describe the more important ft'atures of the collection. The atidesitic 

 rock-* of the Tokatea Range, the Tiiames, and Karangaiiake were compared 

 to show their general correspondence, and those of Kaipanga and Keven's 

 Point, Coromandel, with the rocks of Maresville, Waitekauri, and 

 Waihi. The Beeson's Island rocks were shown to l)e distinct, and present 

 over a verv large area of the southern goldfields of the district. The 

 acidic r:)cks of the peninsula were shown to be largely developed along 

 the east coast, south of Mercury Bay, and to occupy nearly the whole of 

 the Upper Ohinerauri or Waihi Plain. Many samples of different kinds 

 of quartz were exiiibited, in evidence, it was claimed, that most of ttie 

 reefs liad been deposited by hydrothernial action, and in support of this 

 cases were cited in which reefs of crystalline quartz could be traced until 

 they passed into undoubted geyser deposits accumulated on the present 

 surface of rocks of late Miocene age of the Beeson's Island group. 



Sir James Hector said that Mr. McKay's magnificent series of rock 

 specimens from the Cape Colville district would greatly increase our 

 knowledge of this miportant goldfield. Even a superficial inspection of 

 such large specimens would enable the cabinet student to acquire a bettor 

 notion of the field geology than could usually be obtained from ordinary 

 hand specimens. Large blocks also permitted of a much better selection 

 being made for microKcopic and chemical study. He did not altogether 

 agree with the introduction of the terms " sphirulite " and " pearlite " as 

 distinctive characters, seeing that they were structural forms of a variety 

 of rockrt. A most important point was mooted by Mr. McKay. AIJ 

 geolosists were agreed that beside.s a core of ancient rock there were 

 several succeeding series of igneous rocks belonging to widely different 

 geological periods. As in other parts of the world, the core had formed 

 the anvil against which the later-formed rocks were crushed, faulted, and 

 impregnated with mineral veins. The last outbursts were certainly 

 rhyolites, and if tiie suggestion that these were auriferous was correct it 

 was difficult to see why goldfields should not extend over much larger areas 

 of the North Island than yet discovered. Of course, the transfusion of 

 the gold into rbyolite from the underlying rocks by solfatara action 

 would account for local impregnations; but if the formation of the reefs 

 took place after the date of the rhyolite outbursts, which seemed to be 

 the author's contention, that was a novel idea that would requite full dis- 

 cussion after the true nature of the rocks had been obtained by experts. 

 Mr. McKay had done the most laborious part of the work in collecting 

 ample material in a most thorough manner. 



The Chairman thanked Mr. McKay for exhibiting these interesting 

 specimens, and for his explanation as to their nature and the character 

 of the geological district from which they were collected. If the hydro- 

 thermal action in the formation of gold was proved it would settle a most 

 important question. 



Third Meeting: 17th August, 1898. 

 Mr. E. Tregear, President, in the chair. 



Neiv Member. — Mr. J. Singer. 



Paper.— On "Volcanoes of the Pacific," by Coleman 

 Phillips. {Transactions, p. 510.) 



The Chairman, in inviting discussion, said the dates of the eruptiojas 

 mentioned should he given before we could determine whether they were 



