338 Transactions. 



IV . Age of the Kocks. 

 ^4. Age of the Metamorphic Hocks. 



Hector early classed the hornblende schists in his Te Anau series on 

 account of their lithological resemblance to rocks of the typical area. 

 He referred the Te Anau series to the Devonian period, because in 

 Nelson Province the rocks were thought by him to underlie the Maitai 

 slates, which were classed as of Carboniferous age. 



Hutton,* in 1875, placed the rocks in his Kaikoura formation, 

 corresponding to the Te Anau series of Hector. Of the age of the 

 Kaikoura formation he says, "As it underlies quite unconformably the 

 Maitai formation, which is of Lower Jurassic or Triassic age, we may 

 consider it for the present as belonging to the Carboniferous period." 



In 1877 Hectorf placed the Te Anau series in the Maitai system, to 

 which he now ascribed a Triassic age. Subsequently, however, he gave 

 up this correlation, and the Maitai system was referred back to the 

 Carboniferous age. 



In 1885 Hutton J gave up his name of Kaikoura formation in favour 

 of the nomenclature of Hector. At the same time he adopted the corre- 

 lation of the Geological Survey for the Maitai system. 



In 1877 Park§ reported on the Bluff Peninsula at the instance of the 

 Geological Survey Department. He says, " There is only one sedi- 

 mentary formation represented in this area, and, although it contains 

 no fossil remains, it is referred to the Te Anau series, to which the 

 mineral character of its rocks have some resemblance." 



In his latest work Park|| refers to these schists as argillites. In one 

 place (p. 42) he says they are " of the Wangapeka formation (Mana- 

 pouri system, Silurian age) "; in another place (p. 46) they are " argil- 

 lites that belong to Kakanuian or Middle series (Ordovician age) of the 

 Manapouri system." 



Present Conclusions. — In the entire absence of palaeontological and 

 stratigraphical evidence we have to rely solely on lithological evidence. 

 Previous investigators have apparently failed to recognize the extremely 

 metamorphic state of the schists, and have assigned to them a correlation 

 that their original nature does not justify. 



The dykes of diabase at Green Point (amphibolite in the schist 

 series), however, are rocks similar to those of the Te Anau series — namely, 

 greenstones, aphanite, breccias, or greenstone breccias in the Te Anau- 

 Wakatipu area, and diabase and diabase breccias in the Nelson District. 

 In the absence of other evidence, therefore, we shall place the basic dykes 

 in the Te Anau series of the Maitai system. The porphyry, therefore, 

 and the hornblende schists will be somewhat older than the basic dykes, 

 but there is at present no reason to remove them altogether from the 

 same series. 



B. Age of the Intrusive Rocks. 



The evidence for the age of the plutonic rock is even more scanty. 

 Park, in 1887, thought the mass was of late Carboniferous age, for he 



* Hutton, F. W., " Geology of Otago " (1875), p. 36. 

 f Hector, Rep. N.Z. Geol. Surv., 1877. 



$ Hutton, F. W., " Sketch of the Geology of New Zealand," Quart. Journ. Geol. 

 Soc, vol. 41, p. 191 et seg. (1885). 



§ Park, J., " The Geology of Bluff Peninsula," Rep. N.Z. Geol. Surv., 1887-88, p. 72. 

 || Park, J., " Geology of New Zealand," 1910. 



