768 E. C. ANDREWS 



New Zealand, there seems to be no reason now for classing them as Paleozoic. 

 As regards the Manapouri rocks of southwestern Otago, they may, of course 

 (with the exception of some intrusives), be very ancient; but their relations to 

 other systems are absolutely unknown. It may be that this is an upfaulted 

 block from which a Mesozoic cover has been removed. So far as I know there 

 is no evidence of later formations having been folded against it. 



The remarkable flat -lying schists of central and eastern Otago are, again, 

 of indefinite age. Marshall regards them as metamorphosed Mesozoics. 

 He traces a transition to the unaltered "Maitais," but in eastern Otago, along 

 the junction of the schist and greywacke rocks there is a complex of faulted 

 blocks (greywacke now forming the surface in some and schist in others) which 

 had, there can be no doubt, been planed down before the deposition of what I 

 call the "covering strata." Later faults, which affect the cover also, have 

 sometimes followed the lines of the older breaks, but have reversed the throw. 



As to the direction of folding in New Zealand I have formed no opinion. 

 The latest or Kaikoura folding was accompanied by the formation of great 

 reverse faults in the northeastern part of the South Island, and these hade to 

 the northwest. Many small reverse faults in the Wellington neighbourhood, 

 which intersect ( ?) Triassic rocks and were perhaps developed during the 

 Mesozoic period, hade in the same direction. 



One question of great importance is that of the source of the enormously 

 thick "Maitai" sediments, which consist, from end to end of New Zealand, 

 almost universally of the little-worn detritus from acid igneous rocks. Evi- 

 dently these deposits accumulated not far from a great land mass, but I know 

 of no evidence as to the position of that land mass. Apparently the New 

 Zealand area sometimes formed a part of the continent, for at a number of 

 places there are deposits containing Mesozoic plants. 



So far as I know there was no strong folding accompanying the formation 

 of the Hauraki gold deposits, but there have been considerable "block" 

 movements since. 



EVIDENCE OF THE ORE DEPOSITION 



It is proposed here to see what light may be thrown on the 

 possible structural relations or differences of Australasia, New 

 Guinea, and New Zealand, by a study of the peculiarities of ore 

 deposition in certain areas within these regions. In this connection 

 it is proposed to deal principally with one set of minerals only, 

 namely, the tin group, although conclusions equally interesting 

 would have been forthcoming from a consideration of the gold and 

 copper, together with the silver-lead and zinc groups. 



Thus with regard to gold it would have been possible to elaborate 

 with a wealth of detail the knowledge that the gold deposits of 



