re no craters
or cones of eruption to be seen; so that we may infer that the sheets,
at least, were extruded from fissures in the manner of those of the
Colorado or Idaho regions of America. Proceeding still further south
into the interior of the island, we here find a lofty plateau of an
average elevation of 2,000 feet, interposed between the Tertiary beds of
the Upper and Middle Waikato, and formed of trachytic and pitch-stone
tuff, amongst which arise old extinct volcanic cones, such as those of
Karioi, Pirongia, Kakepuku, Maunga Tautari, Aroha, and many others.
These trachytic lavas would seem to be more ancient than the basaltic,
previously described.

(_b._) _Taupo Lake, and surrounding district._--But of all these
volcanic districts, none is more remarkable than that surrounding the
Taupo Lake, which lies amidst the Tertiary strata of the Upper Waikato
Basin. The surface of this lake is 1,250 feet above that of the ocean,
and its margin is enclosed within a border of rhyolite and
pitchstone--rising into a mass of the same material 1,800 feet high on
the eastern side. The form of the lake does not suggest that it is
itself the crater of a volcano, but rather that it was originated by
subsidence. On all sides, however, trachytic cones arise, of which the
most remarkable group lies to the south of the lake, just in front of
the two giant trachytic cones, the loftiest in New Zealand, one called
Tongariro, rising about 6,500 feet, and the other Ruapahu, which attains
an elevation of over 9,000 feet, with the summit capped by snow. These
two lofty cones, standing side by side, are supposed by the Maoris to be
the husband and wife to whom were born the group of smaller cones above
referred to as occupying the southern shore of Taupo Lake. The volcano
of Tongariro may still be considered as in a state of activity, as its
two craters (Ngauruhoe and Ketetahi) constantly emit steam, and several
solfataras break out on its flanks.[2]

(_c._) _Roto Mahana._--In a northerly direction from Tongariro, and
distant from the coast by a few miles, lies in the Bay of Plenty the
second of the active volcanoes of New Zealand, the volcanic island of
Whakari (White Island), from the crater of which are constantly erupted
vast masses of steam clouds. The distance between these two active
craters is 120 nautical miles; and along the tract joining them
steam-jets and geysers issue forth from the deep fissures through which
the lava sheets