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THE GEOLOGY OP NEW ZEALAND. 
The geological features in New Zealand are so clearly 
marked, that there is no difficulty in detecting the character 
of the agent employed. New Zealand may be properly 
called a volcanic country, since nearly half its mountains 
are extinct craters : volcanic action, however, seems to 
have been greater in particular localities ; in the north the 
centre was at Otaua, near the Bay of Islands, which is 
a remarkable district; an immense crater rises above the 
level of the surrounding country, with steep precipitous 
cliffs of pipeclay, which, on the summit, incline inwards, 
so as to form a vast bowl several miles in diameter ; this 
appears to have been formerly a huge crater ; but when that 
became exhausted, a series of smaller ones broke out on the 
sides, which are more or less active, and filled with water of 
great depth, from which streams of gas escape in every part ; 
one of these crater lakes contains white mud, which bubbles 
up in all directions ; in another, the heated gas is emitted 
from innumerable pores, the highest degree of temperature 
being 196 Fab.., the ground seems to be constantly subsiding, 
probably in the same degree as the mud is ejected from the 
neighbouring spots ; it is evident, that after the grand crater 
became extinct, it was covered with a most luxuriant growth 
of Kauri timber, the leaves of which, in some places, form 
a turf stratum of nearly twelve feet ; in every part the im- 
mense roots are still perfect in the ground, the smaller ones 
being encased with pure sulphur ; the lakes also are filled 
with timber, and even the leaves and cones are as fresh as 
though they had just fallen from them.* 
The surrounding plain of Taiamai is covered with scoria 
and large masses of rock, which have evidently been ejected 
from some of the many neighbouring craters ; there are also 
large quantities of conglomerated iron sand, which every- 
* These parts are resorted to by scrofulous and diseased natives, especially 
females, from the Bay of Islands, for the benefit of vapour baths, to form which 
they simply scoop out a little hollow in the sand, about a foot deep, lining it 
with old mats, upon which the patient is placed with a blanket thrown over 
the person to keep in the heat. The invalids generally remain about a month 
at the baths, and have little temporary huts erected, which give a singular 
appearance to this lonely and desolate region. 
