GEOLOGY OF NEW ZEALAND. 219 



WeUington ; but these are thought to he older. I have meutioned 

 that a line of granite exposures occurs along the ge- anticlinal 

 axis in the South Island, from Paringa to Separation Point in 

 Nelson ; and the question naturally suggests itself, Are these 

 rhyolites of the North Island derived from a northerly extension 

 of the granite zone of the South Island ? It seems possible that 

 granitic rocks may be nearer the surface here than they are in 

 the northern parts of the province of Auckland, and this may account 

 for the eruption of rhy elites only in the centre of the North Island, 

 They may be merely a recliauffee of Maitai granites of the 

 northern part of the ge-anticlinal. 



Hot Speings. 



In the South Island hot springs are known only in two places, 

 one in the Hanmer plains, Amiiri county, and the other near Lake 

 Sumner, about 40 miles S.W. of the first. In the North Island 

 there is only one hot spring east of the main range ; it is near 

 Waiapu, in the East Cape district. But west of the main range they 

 are very numerous ; all the more important ones lie in a broad 

 band along the axis of the ge-anticlinal, from the base of Tongariro, 

 through Lake Taupo and the upper Waikato, to Lake Eotomahana 

 and Lake Hotorua, forming one of the most wonderful regions in 

 the world. Dr. Hoehstetter distinguishes three parallel lines 

 of springs ; but it requires some determination in the tracing of 

 lines to make this out. North of this region the hot springs are 

 isolated. They occur at Pupunui on the Thames, near Lake 

 Whangape in the Lower Waikato, at Waiwera near Auckland, at 

 ITahiu-angi, also near the Bay of Islands, and on the Great Barrier 

 Island. Geysers, solfataras, fumaroles, mud-volcanoes, and springs 

 depositing siliceous sinter are confined to the central rhyolitic region 

 of the North Island. 



The best description of the hot-spring region will be found in 

 Dr. Hochstetter's works. The E-ev. E,. Abbay has given a very clear 

 explanation of the formation of our sinter terraces *. Accounts of 

 the mineral waters have been given by Mr. Skeyt and by Dr. Hector J. 



MiNEKALS. 



An exhaustive list of all the minerals hitherto found in New 

 Zealand has been given, by Mr. S. H. Cox§. Among the more 

 interesting are platiridium, osmium-iridium, hessite, sapphire, 

 spinel ruby, emerald, tridymite, nephrite, and kyanite. No 

 diamond has as yet been found, A curious jet-like mineral occurs 

 in veins, or lining veins, in sandstones belonging to the Wanganui 

 System at One- tree Point, on the west side of Whangarei Harbour Ij. 

 Gold occurs in the Takaka System and in the Maitai System, where 



* Quart. Journ. Geol. Soc. xxsiv. p. 170. Foi* an account of the shape of 

 the basin and pipe of Te Tarata, see Trans. N. Z. Inst. i. p. 162 (new ed. p. 106). 

 t Trans. N. Z. Inst. x. p. 243. :j: Handbook of A^ew Zealand, 1883. 



§ Trans. N. Z, Inst. vols, xiv., xv., and xvi. 

 II Trans. IN". Z.^Inst. iii. p. 250. 



