262 Transactions. 



progress, and the surface of the monadnock at Trig. Station U was levelled 

 by wave-action at this time. 



The uplift continued after the deposition of the gravels of the 

 " 500-foot " terraces, and the land rose at least 250 ft. ; again a period 

 of considerable standstill and probable slight depression intervened : the 

 sea advanced upon the recently formed strand-plain, and wore it back 

 until a bold line of high sea-cliffs marked the edge of the present high- 

 level terraces. The movement of uplift was renewed, and continued inter- 

 mittently until comparatively recent times, the various periods of standstill 

 being well illustrated by numerous terraces, such as those well developed 

 where the Buller and Totara Rivers cross the coastal lowlands. It is 

 tolerably certain that depression Varied the main movement of uplift, such 

 depression being indicated in particular by the relations of the Pleistocene 

 beach-sands to the Tertiary and older underlying rocks near the mouth of 

 the Waitakere River (see section AB). The covering of drift over the 

 lowlands consists largely of beach deposits left, as the sea retreated ; but, 

 in addition, a quantity of material has been brought down and deposited 

 by the Buller River on its lateral terraces, deposition having taken place 

 owing to the seaward extension of the delta of that river during the early 

 stages of uplift. 



The most recent events in the geological cycle have been the formation 

 of the present Buller delta and a general prograding of the coast-line, except 

 where rocky headlands disturb the uniformity of the sea-margin and are 

 being rapidly undercut into steep and lofty cliffs. These events are still 

 in progress. 



Acknowledgements. 



In conclusion, the writer wishes to thank Mr. P. G. Morgan, Director 

 of the Geological Survey, for permission to present this paper, and Mr. 

 G. E. Harris, of that Department, for assistance in the preparation of 

 locality map and sections, and to express his indebtedness to Mr. C. A. 

 Cotton, of Victoria College, for much helpful criticism and advice. 



Art. XXXIV. — Some Intrusive Igneous Rocks from the Westport District. 



By J. A. Bartrum, New Zealand Geological Survey. 



(By permission of the Director of the Geological Survey.) 



[Read before the Wellington Philosophical Society, 27th August, 1013.] 



Introduction. 



The aim of the present paper is to give a petrographical account of several 

 interesting rock-types encountered during the course of the recent work of 

 the Geological Survey in the Westport district. A statement of consan- 

 guinity and absolute classification can only be made when the requisite 

 chemical analyses are available, but it is believed that the petrographical 

 descriptions indicate these sufficiently well in most cases. Since one rock, 

 however — provisionally classed as a syenite-porphyry — has a rare occurrence 

 in New Zealand, it would be more satisfactory were the classification justified 

 also by chemical analysis. Another type — a monchi quite — though known 



