II— .GEOLOGY. 



Akt. XXIX. — On the Foliated Bocks of Otago. 

 By Professor F. W. Hutton, F.G.S. 



[Bead before the F Ivilosophical Tnstlhdc of Canterbury, 4th November, 



1891.'] 



The foliated rocks of Ofcago are found in two districts, sepa- 

 rated from each other by a band of sandstones and slates, 

 about eight miles broad at its narrowest, which belongs to the 

 Maitai or Carboniferous system. 



1. Northern Otago. 



The first of these districts is in north-eastern and central 

 Otago, the rocks found in it being the " foliated schists " of Sir 

 James Hector,"' and the " Wanaka and Kakanui formations" 

 of my " Eeport on the Geology of Otago" (Dunedin, 1875), 

 p. 26. These rocks extend in a band — some one hundred and 

 thirty miles long and eighty miles broad — across the north- 

 eastern part of Otago, where they form a single broad anti- 

 clinal curve, the axis of which runs from near Dunedin, west 

 of Cromwell, to Lake Wanaka. The rocks lie remarkably flat 

 (for foliated schists) over the whole area, dips of more than 45° 

 being rare, and almost exclusively confined to the flanks of the 

 curve. The average dip is between 25° and 30°. The rocks 

 are not contorted or plicated in the usual meaning of the 

 terms, but in the lower part of the Wanaka series they often 

 have a waved or corrugated structure. All the rocks of the 

 Wanaka series are foliated, and nearly all are true mica-schists, 

 varying from coarsely foliated, with lenticular plates of pure 

 quartz, to finely foliated, with nearly parallel foliar. The 

 Kakanui series is composed at the base of fine-grained mica- 

 schists and silky phyllites, passing upwards into beds of 

 quartzite and clay-slate, which is cleaved only in the plane of 

 stratification. There is, however, no distinct sepai'ation of the 

 Wanaka from the Kakanui series, but one passes insensibly 



* Quar. Jour. Geol. Soc. of London, 1865, vol. xxi., p. 128. 



