THE NEW ZEALAND GAZETTE. 173

intermittent springs belong to the alkaline class,
in which are also included the most of the ordi-
nary boiling springs. Sulphurets of Sodium and
Potassium, and Carbonates of Potash and Soda,
are the solvents of the Silica, which, on the cool-
ing and evaporation of the water, is deposited in
such quantities as to form a striking character-
istic in the appearance of these springs.

Here I must leave this interesting subject.
To enter more deeply into the theory of these
phænomena would be out of place here. It may
be, however, well to mention that numerous
facts prove that the action which gives rise to
the hot springs is slowly diminishing.

I must also state my conviction that ere
long these hot springs will be visited by many
travellers, not only for the sake of their beauty
and interest, but also for the medicinal virtues
they have been proved to possess. Already
many Europeans have bathed in, and derived
benefit from, the warm waters at Orakei-
korako and Rotomahana.

I am unwilling to omit the interesting
legend current among the Natives in reference
to the origin of these hot springs. The legend,
as told by Te Heuheu, the great chief on the
Taupo lake, is the following :-

The great Chief Ngatiroirangi, after his
arrival at Maketu at the time of the immigration
of the Maories from Hawaiki, set off with his
slave Ngauruhoe to visit the interior, and,
in order to obtain a better view of the
country, they ascended the highest peak of
Tongariro. Here they suffered severely from
cold, and the Chief shouted to his sisters on
Whakari (White Island) to send him some fire.
This they did. They sent on the sacred fire
they brought from Hawaiki, by the taniwhas
Pupu and Te Haeata, through a subterranean
passage to the top of Tongariro. The fire
arrived just in time to save the life of the
Chief, but poor Ngauruhoe was dead when the
Chief turned to give him the fire. On this
account the hole through which the fire made
its appearance-the active crater of Tongariro-
is called to this day by the name of the slave
Ngauruhoe; and the sacred fire still burns
within the whole underground passage along
which it was carried from Whakari to
Tongariro.

This legend affords a remarkable instance of
the accurate observation of the Natives, who
have thus indicated the true line of the chief
volcanic action in this island.

Having now described the older and more
extensive volcanic phænomena of the interior,
I proceed to notice the later phænomena of
volcanic action in the immediate neighbour-
hood of Auckland.

THE AUCKLAND VOLCANIC DISTRICT.

The Isthmus of Auckland is completely
perforated by volcanic action, and presents a
large number of true volcanic hills, which, al-
though extinct and of small size, are perfect
models of volcanic mountains. These hills
-once the funnels out of which torrents of
burning lava were vomited forth, and after-
wards the strongholds of savage cannibals-
are now the ornaments of a happy land the
home of peaceful settlers, whose fruitful
gardens and smiling fields derive their fertility
from the substances long ago thrown up from
the fiery bowels of the earth.

My Geological Map of the Auckland Dis-
trict contains no less than sixty points of vol-
canic eruption within a radius of ten miles-
the variety of which, together with the regu-
larity of their formations, gives very great
interest to this neighbourhood. The newer
volcanic hills round Auckland are distinguished
from the older ones in the interior, not only by
their age, but by the different character of their
lava---the older being trachytic, while the
Auckland are all basaltic. I have not yet
mentioned the difference between Trachyte
and Basalt. I will therefore say a few words
in explanation. The difference consists in the
minerals of which the rocks are composed.
Trachyte is composed of a mixture of glassy
feldspar (Sanidin) and hornblende: obsidian
and pumice-stone are the usual concomitants of
trachytic lava. Basalt consists of a minutely-
crystalline mass of feldspar mixed with augit: an
admixture of greenish grains of Olivin
is characteristic of basalt.

In order to gain a clear idea of the history
of the Auckland Volcanoes, we must suppose
that before the period in which the Auckland
Isthmus was slowly raised above the level of
the sea, a submarine volcanic action was
already going on. The products of this sub-
marine action are regular beds of volcanic
ashes, which form highly interesting circular
basins with strata always inclining from within,
outwards. You will at once remember several
striking examples which I can mention-as the
Pupuki Lake on the North Shore; Orakei
Bay in the Waitemata; Geddes's Basin
(Hopua) at Onehunga; and the tidal basin
(Waimagoia) at Panmure; -Pupuki Lake, be-
lieved to be bottomless, has been ascertained by
Captain Burgess (who kindly sounded it at
my request) to be only 28 fathoms. I call
those basins and similar formations, tuff craters
or tuff-cones. The excellence of the soil of
Onehunga and Otahuhu is owing to the
abundance of such formations, decomposed
strata of which form the richest soil that can be
met with. It is curious to observe how the
shrewder amongst the settlers, without any
geological knowledge, have picked out these
tuff-craters for themselves, while those with
less acute powers of observation have quietly
sat down upon the cold tertiary clays.

After the submarine formation of the tuff-
craters, the volcanic action continuing, the Isth-
mus of Auckland was slowly raised above the
sea, and then the more recent eruptions took
place by which the cones of scoria, like Mount
Eden, Mount Wellington, One Tree Hill,
Mount Smart, Mount Albert, and Rangitoto,
were formed, (and great out-flowings of lava
took place. Many peculiar circumstances,
however, prove that those mountains have not
been burning all simultaneously. It can
easily be observed that some lava streams are
of an older date than others.) In general
the scoria cones rise from the centre
of the tuff-craters, (Three Kings, Wai-
tomokia, Pigeon Hill near Howick.) Oc-
casionally, as in the instance of Mount Wel-
lington, they break through the margin of
the tuff-crater.

The Crater System of Mount Welling-
ton is one of the most interesting in
this neighbourhood, as beautifully shown by
the large map, which Mr. Heaphy has kindly
prepared for me from actual survey. (*There
are craters and cones of evidently different ages.
The result of the earliest submarine eruptions
is a tuff-crater. The Panmure road passes
through the tuff-crater, and the cutting through