Thomas. — Geology of Tongariro and Tavpo. 339 



enabled him to give a remarkably good account of some of its 

 general features, and especially of its wonderful development 

 of geysers and hot springs. He was, however, unable to 

 ascend any of the great volcanic cones in the district, and he 

 states that, although he gazed longingly at the massive out- 

 lines of Tongariro and Euapehu, far to the south of the 

 limit reached by him, neither time nor opportunity offered 

 itself. Moreover, the Maoris had declared the mountain 

 tajm, and would have strenuously opposed any projected 

 ascent. 



For many years little was added to our knowledge of the 

 geology of the district, and it was not until after the unlooked- 

 for eruption of Tarawera had recalled attention to the subject 

 in so startling and emphatic a manner that further contributions 

 were published. Mr. Cussen, in a paper read before this In- 

 stitute last year, gave a general description of Lake Taupo 

 and the country to the west, whilst in the reports on the Tara- 

 wera eruption by Mr. Percy Smith and the writer respectively 

 there will be found additional information concerning the 

 Taupo volcanic zone and the cones to the south. Mr. Park 

 and Mr. L. Cussen have also published accounts of the ascent 

 of Euapehu. 



Nevertheless the detailed description of the geology of the 

 great cones to the south of the lake has not yet been given, 

 and there is many a problem connected with the geology of 

 the district which has scarcely been attacked. The present 

 contribution to the subject is founded on observations made 

 dming various visits to the Taupo district, more particularly 

 in January, 1888, when the writer passed a few days en- 

 camped at the foot of Tongariro. His time was chiefly spent 

 in the examination of Tongariro ; and a contemplated visit to 

 Euapehu was delayed by other work undertaken for the Go- 

 vernment. He trusts, however, to have an early opportunity 

 of making a more extensive examination of other parts of this 

 locality. 



Perhaps the greatest interest centres round the Euapehu- 

 Tongariro chain of volcanic mountains, for we have here 

 no iewer than three cones — viz., Euapehu, Ngauruhoe, 

 and Tongariro — which have shown signs of greater or less 

 volcanic acti\'ity within recent years. This chain (see 

 Plate XXVI. ), which has a length of fifteen or sixteen miles 

 in a direction 26° east of north, rises up from the centre of 

 a plateau nearly 2,000ft. above the sea-level. The plateau 

 is bounded on the east by the Kaimanawa Eange, composed 

 of the ancient Maitai (Carboniferous) slates and sandstones, 

 rising to a height of 5,225ft. in the Umukarikari Moun- 

 tain. The Euapehu-Tongarh'o Une is nearly parallel to this 

 range at a distance of some ten miles. To the west the 

 22 



