424 THE GEOLOGY OP DUNEDIN (NEW ZEALAND). [Aug. I906, 



the great difficulty of the country to be worked, and the vast oppor- 

 tunities awaiting the geologists settled there. He thought that this 

 the parent Society was always very fortunate in receiving the best 

 of their work from its children living in all parts of the world, and 

 especially in having presented to it such an able paper from a colony 

 so interesting as JSew Zealand. 



Dr. Teall regretted that he had not heard the first part of the 

 paper, and could not therefore do justice to it ; but he was glad of 

 the opportunity of expressing the pleasure that he felt, in listening 

 to even a small portion of what was evidently an important com- 

 munication, and at meeting Capt. Hutton, with whose name and 

 work he had been so long familiar. 



Various theories had been proposed to explain the succession of 

 igneous rocks, but none was applicable to all instances. This being 

 the case, it was most important that the sequence in a large number 

 of instances should be carefully recorded, and on those grounds he 

 welcomed this paper. Of late, the view that the mixing of magmas 

 and the modification of magmas by the absorption of adjacent rocks 

 were important factors in determining varieties of igneous rocks 

 had been gaining ground. He had not himself met with evidence 

 of this on a large scale, but he was perfectly prepared to believe 

 that it existed. 



Prof. Watts congratulated the Author on the richness of the 

 petrology of the Dunedin district. He referred especially to the 

 fact that the Author had tested the new classification in his rock- 

 sequence, and had found it wanting. 



Prof. Hull enquired as to the evidence of the former elevation 

 of the area described to 1500 feet above its present level. 



ALr. A. P. Young, commenting on the persistence of the basalts 

 which appear in the earliest, and last till the latest, stage of 

 volcanic activity, said that he wished to ask whether some apparent 

 repetitions in the series might not be referred to faults. As an 

 alternative to the Authors hypothesis of the complete disappearance 

 of amphibole through resorption, the speaker suggested that the 

 presence or absence respectively of the mineral in closely- allied 

 rocks might, in some cases, be explained by the tendency of amphi- 

 bole to crystallize out at great depths from magmas which, at 

 higher levels, yielded biotite or pyroxene in place of amphibole. 



Mr. H. H. Thomas asked a question concerning the Author's 

 explanation of the occurrence of analcime in some of the rocks. 



Capt. Hutton, replying on behalf of the Author, said that the 

 latter gave no theory as to the occurrence of analcime in the rocks. 

 With reference to the question asked by Prof. Hull, there was a 

 general agreement, both biological and geological, in favour of an 

 elevation of the New Zealand area in later Pliocene times. The 

 actual elevation in the south of New Zealand was estimated from 

 the depths of the fiords below sea-level. 



