PAPERS READ IN SECTION C. 



1.— KEPORTS OF THE llESEARCH COMMITTEES ON STRUCTURAL 

 FEATURES AND GLACIATION. 



Communicated by Professor P. MARSHALL, D.Se., Otago University. 



A. — Structukal Features, New Zbalajid. 



Recent work of the reorganised geological survey under Dr. J. M. 

 Bell has added greatly to our knowledge of some of the important 

 structural features of both islands. The reports deal with isolated 

 districts in various portions of the island. The areas have been 

 selected because of their economic importance, but the work that has 

 been done has taken a wide view of the scientific problems that have 

 been encountered. 



Bulletin 1, by Dr. Bell and C. Fraser, shows that there is an 

 apparent conformity of rock series across the central portion of the 

 Southern Alps in the section from the Wilberforce River to the 

 Arahura. The structure is that of a complex synclinorium. The meta- 

 morphism gradually increases from east to west until intrusive granite 

 is encountered. On the west of this again in the foot hills unaltered 

 rocks of perhaps the same series are found. It is suggested that their 

 occurrence in this position is due to faulting. In Bulletin 6, Mr. P. 

 Morgan has found much the same structure in the district extending 

 fifty miles further south. Here, however, a fault of great importance 

 is described along the line of magnesian intrusives (Pounamu series), 

 and the western sedimentaries are slightly folded with an east and 

 west strike. 



In Bulletin -3, the north-west of the South Island is described. 

 This region includes graptolite beds of Ordovician age. The strike is 

 north-north-west, and the stnacture so complicated that it is impossible 

 to describe it in small space. The metamorphism increases to the east. 

 An unconformitj^ separates the Ordovician from older rocks, and there 

 are huge thrust planes and gravity faults, with several intrusions of 

 various plutonics. 



In Otago, Park (Bulletins 2, 5, and 7) has described a series of 

 faults striking nearly north and south across the area of schists in 

 Central Otago. Owing to these faults the several ranges of mountains 

 are left as block mountains. It will be noticed that the direction of 

 the faults is at right angles to the strike of the schist folds. 



In Coromandel, C. Fraser and J. H. Adams have found the sti-ike 

 line nearly due north and south as described in Bulletin 4. It is said 

 with some hesitation that there are three unconformable series of 

 rocks, the youngest of which is Jurassic. The Jurassic rocks alone are 

 fossiliferous. 



In the extreme north the direction of folding is found by E. 

 Clarke to be north-north-west and south-south-east, but the structure 

 is extremely difficult to decipher. 



Professor Gregory has in several publicationsf referred to two 

 periods of folding in the main structure of New Zealand. The major 



