You ask for a few notes on any geographical researches in New Zealand and more especially
on the change in geographical features, caused by the volcanic eruption at Tarawera
on 10th June, 1886. As I have just come from that district, and also visited it before
the eruption, I will be able to state from fresh recollection the changes, that have
occurred. Tarawera is in the middle of the volcanic zone or belt, which extends straight
from Ruapehu-Mountain in a N. N. East direction to White Island, a length of 160 miles
by a breadth of about 10 or 20 miles. Within this wonderful region there are hundreds
of hot springs, pools, geysers, steam-vents, boiling mud, lakelets of deep blue, green,
vermillion and other hues, indicative of the ingredients of the rocks through which
the steam and hot springs have come. Standing on the summit of Mt. Tarawera or Tauhra
or Tongariro or other of the great dormant volcanic cones, the eye looking north and
south can take in the main features of the whole scene of mountains, lakes, forests
and open plains, enlivened not by the curling smoke from human habitations, but by
pillars and clouds of sulphurous vapour, steaming up and revealing the localities
of innumerable hot springs at all altitudes and in unthought of places. Previous to
the morning of the 10th June 1886, it was thought, that the thermal springs were the
last act in the theatre of volcanic energy in New Zealand; but at half-past one o'clock
on that morning the inhabitants of Rotorua and Wairoa, respectively about 13 and 7
miles from Tarawera, were aroused by violent shakings of the ground and rumbling noises,
which soon increased to a terrific roar, with vast clouds of smoke, vapour and flame
illuminating with lightnings, rising from the summit of Tarawera and over the Rotomahana
lake. Showers of ashes and mud fell over the surrounding country, principally to the
north-east, being driven thither by a strong south-west wind. The extreme violence
of the eruption was over several hours before daylight; but the country was so enshrouded
in sulphurous smoke and vapours and the roads blocked and obliterated with mud, stones
and fallen timber, that it was several days before a near approach could be made to
the scene of the disturbance, when it was found, that the Rotomahana lake with the
two beautiful sinter terraces on its surrounding slopes had disappeared, and that
in their place appeared a chasm about a mile wide and fully 500 feet deeper than the
former depression of the lake, and extending in a great fissure northerly through
Tarawera mountain and southerly for several miles — the total length of fissure from
end to end being nine miles and varying in width from a mile to about 200 yards and
at the ends tapering off into isolated craters. The ejecta from this great fissure
have covered the immediately surrounding country for a few miles to a great depth.
The summit of Tarawera mountain, formerly 3606 feet above sea-level, is now 3776 feet,
having received a coating 170 feet deep. Two native settlements on the shores of Lake
Tarawera with about 100 inhabitants are buried 30 or 40 feet deep, and the valley,
through which the waters of Lake Rotomahana flowed on to Lake Tarawera, is now entirely
filled up and obliterated as though by a great snow drift. Indeed the present appearance
of the country for a few miles on each side of the fissure is that of a country covered
with snow, the mud having weathered white and vegetation not yet begun, nor is it
likely to reappear for a time, as the surface is furrowed anew by every succeeding
rainfall. The shower of mud and fine ash fell over an area of nearly 6000 square miles
over the land, but on most places only to a depth of an inch or two or even less than
that. The country affected is nearly all unoccupied native territory, with the exception
of a comparatively small area of European settlement on the coast of the Bay of Plenty.
The cattle had to be driven from the settlements to fresh pastures for a short time;
but this inconvenience has been repaid by the volcanic dust and mud renovating the
pastures with a better growth of grass, than existed before. With the exception of
the fissure and the change of levels in its immediate vicinity and the creation of
several small lakes in its course, there is no permanent change in the configuration
or conditions of the country. There were slight temporary variations in the temperature
and activities of some of the Geysers and other springs in the volcanic zone, just
sufficient to show a relationship with Tarawera, but otherwise there have been no
changes.
