have formerly been extruded. Numerous lakes also occupy
the larger cavities in the ground; and hot-springs, steam-fumaroles and
solfataras burst out in great numbers along the banks of the Roto Mahana
Lake and the Kaiwaka River by which it is drained. Amongst such
eruptions of hot-water and steam we might expect the formation of
siliceous sinter, and the deposition of sulphur and other minerals; nor
will our expectations be disappointed. For here we have the wonderful
terraces of siliceous sinter deposited by the waters entering Roto
Mahana as they descend from the numerous hot-springs or pools near its
margin. All travellers concur in describing these terraces as the most
wonderful of all the wonders of the Lake district of New Zealand--so
great is their extent, and so rich and varied is their colouring.

The beautiful map of Roto Mahana on an enlarged scale by Hochstetter
shows no fewer than ten large sinter terraces descending towards the
margin of this lake, besides several mud-springs, fumaroles, and
solfataras. But the largest and most celebrated of all the sinter
terraces has within the last few years been buried from view beneath a
flood of volcanic trass, or mud, an event which was as unexpected as it
was unwelcome. In May, 1887, the mountain of Tarawera, which rises to
the north-east of Roto Mahana, and on the line of eruption above
described, suddenly burst forth into violent activity, covering the
country for miles around with clouds of ashes, and, pouring down
torrents of mud, completely enveloped the beautiful terrace of sinter
which had previously been one of the wonders of New Zealand. By the same
eruption several human beings were entombed, and their residences
destroyed.

The waters of Roto Mahana, together with the hot-springs and fountains
are fed from rain, and from the waters of Taupo Lake, which, sinking
through fissures in the ground, come in contact with the interior heated
matter, and thus steam at high temperature and pressure is generated.[3]

(_d._) _Moribund condition of New Zealand Volcanoes._--From what has
been said, it will be inferred that in the case of New Zealand, as in
those of Auvergne, the Eifel and Lower Rhine, Arabia, and Western
America, we have an example of a region wherein the volcanic forces are
well-nigh spent, but in which they were in a state of extraordinary
activity throughout the later Tertiary, down to the commencement of the
present epoch. In most of these cases