THE GEOLOGY OE NEW ZEALAND. 
451 
all their cooking being done in the hot springs, the womens 
backs are not broken with carrying fuel, and further, from 
the warmth of the ground, they were enabled to raise their 
crops several weeks earlier than their neighbours ; but, as a 
counterbalance for these advantages, many fatal accidents 
occur from persons, especially strangers and children, falling 
into those fearful caldrons. 
Roto Mahana, a warm water lake of considerable size, is 
surrounded with innumerable boiling gulfs ; in fact, it is it- 
self nothing but a crater, the sides of which are full of 
action ; it is perhaps one of the most singular places in the 
world, its boiling springs, and natural snow-white terraces 
formed from silicious deposits, are as wonderful as they are 
beautiful. Thence to Hohake and Rotokawa there is nothing 
to be seen but jets of vapour, and so on to Taupo, where fear- 
ful gulfs abound at both extremities of that noble lake ; many 
of these boiling springs at Rangatira and Tokanu possess the 
property of changing the nature of anything which may be 
placed in them, and converting them into a beautiful silicious 
substance of pure white, and this is done without any appa- 
rent addition of matter ; but if the article be not entirely 
immersed, having only the water flowing about it, then it 
becomes enlarged by the deposit upon its surface ; the 
process of thus converting wood into stone is very rapid, and 
in some localities, water does not appear to be a necessary 
agent in accomplishing this change ; at Rotorua, large pieces 
of wood are thus agatized by the aid of heated gas, highly 
charged with sulphur, alum, and iron, or other chemical 
substances, which penetrate the pores of the wood, and fill 
them up with silex, converting them into agates, and even 
giving them the transparency of chalcedony. 
At Roto-aira, a beautiful lake at the base of the Tongariro 
range, which attains an elevation of 10,236 feet, boiling 
springs also abound ; the volcano itself is not so lofty, from 
its cone it constantly sends forth a volume of smoke, and 
occasionally of flame, which has been distinctly seen at a 
distance of a hundred and fifty miles,* and although the 
* Formerly, when Tongariro emitted flame, the natives regarded it as a com- 
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