Hill. — Riiapelm and the Volcanic Zone in 1805. 685 



rearrangement of watersheds which then took place owing to 

 differential movements of the land. Finally we arrive at the 

 period of cone-formation ; and undoubtedly a fresh period of vol- 

 canic activity began as the result of earth-movements almost 

 parallel to and on both sides of the major axis of the volcanic 

 zone. How long the activity of the cones along the major axis 

 has continued it is impossible to say ; and it is equally uncertain 

 whether the building-up of these began from the south or the 

 north. The extinct Egmont and the equally extinct Hau- 

 hangatahi to the westward of Euapehu almost imply that 

 these mountains were two of the earlier cones, as from their 

 size compared with all except Euapehu they would require 

 a longer interval of time to cool. In any case, the third 

 period of activity has been more manifest in the southern 

 portion of the zone than elsewhere, and the activity is still 

 greater there than in any other portion of the Island. Ngau- 

 ruhoe is no doubt the youngest of the volcanic cones, as its 

 marvellous symmetry has not yet been broken down like 

 Tongaru'O and Euapehu by the lapse of time and atmo- 

 spheric influence. Tongariro and Euapehu are less active 

 than Ngauruhoe, and there can be little doubt that the two 

 former are in a state of collapse. Euapehu appears, like To- 

 ngariro, to have periods of activity depending on hydrothermal 

 causes. The changes which took place at Te Mari, situated 

 at the north end of Tongariro, in November, 1892, correspond 

 exactly with those which have taken place on Euapehu — first 

 in May, 1887, and again in March of this year. 



At the summit of Euapehu is a crater-lake, situated be- 

 tween the three highest peaks, known as Parae-te-tai-tonga 

 to the south, Euapehu to the west, and Te Heuheu to the 

 north. This crater-lake on its western half is surrounded by 

 glacial ice, which, as the terminal portion of a glacier, actually 

 forms the walls of a sometimes boiling crater. It has hitherto 

 been impossible to learn the depth of the water in the crater, 

 but its temperature appears to undergo important changes, 

 depending possibly on the supply of ice from the mountain. 

 Observers who have seen this crateral lake report it either as 

 being partially frozen over, as being cool, as being warm, or as 

 being in a state of ebullition. When visited by me in March, 

 1890, its waters were boiling rapidly, and there was a wave- 

 like movement from west to east, whilst at intervals of about 

 two minutes steam was suddenly thrown from the surface, 

 and a kind of pulsating movement followed, the waters appear- 

 ing to subside for a short space. There appeared to be little 

 or no space available whereon to stand, assuming it had been 

 possible to reach the lake, except at the south-east bend ; and, 

 as the crater- walls at this point were steaming furiously, and 

 our party had no rope available, no attempt was made to 



