504 Trails actions. — Geology. 



it has even been found proper to invent a new term by 

 denominating that destructive outburst a " hydrothermal 

 eruption." This term may be correct in so far that the 

 vpaters of Rotomahana played a part in the eruption of 

 Tarawera proper, or at least altered the phenomena some- 

 what; but, as it involves the theory that incandescent magma 

 had no important part, if any, in the whole remarkable 

 eruption, I cannot indorse it. 



Next day I went to Ketetahi, where I saw some very fine 

 and powerful high-pressure fumaroles, a great number of 

 minor steam-holes, and a considerable pool of turbid hot 

 water, the overflow of which formed a hot creek. Ketatahi is 

 the most beautiful specimen of a fumarole I have ever seen : 

 it is far superior to Karapiti, or any of the others in the geyser 

 district ; and it is also superior to those in the Yellowstone 

 Park or in Italy. The whole place had, as is usual in hot- 

 springs districts, a smell of sulphuretted hydrogen (H2S). 



After this I ascended the North Crater, went to the top 

 of Tongariro, came back again to the North Crater, and 

 walked over to the Blue Lake, and everywhere I found the 

 surface covered by a thin layer of very fine bluish-grey dust. 

 From the Blue Lake I descended to the northern slope, 

 approaching Te Mari within about 300-400 m. Te Mari had 

 quietened down considerably in the afternoon, and its steam 

 was almost white — i.e., without ashes — but I did not dare to 

 go to its rim after my experiences of the previous night, as a 

 sudden new outbreak, with enormous masses of steam, bombs, 

 and lightning, might have proved very dangerous. 



II. Ngauruhoe. 



I have but little to say about Ngauruhoe. After the 

 information I have received from old settlers and from 

 Maori scholars (compare also what Mr. Willis says in his 

 guide-book) I feel inclined to believe that " Auruhoe," 

 and not " Ngauruhoe," is the right name. I ascended the 

 cone on the 8th December, 1896, over the saddle between 

 its base and the south-eastern spur of the Tongariro system 

 — viz., from about the north-east. The upper parts have 

 a slope of about 35°, and are mostly formed of solid lava. 

 Viscous lava only is likely to build up a cone of that steep- 

 ness. On the lower parts cinders prevail. From the slope 

 and from the top a magnificent bird's-eye view of the 

 Tongariro system is afforded. The crater may be considered 

 as sufficiently known. Its rim has a gap in the north-west or 

 north-north-west; its bottom contains one small cone of some- 

 what solid-looking matter, and, besides, a large and typical 

 broad secondary cinder-cone. The latter is very excentric 

 towards the north-west — in fact, its slope, in the already- 



