392 
“Lying on the surface of this deposit, especially on the 
slopes directed towards the fissure, fragments of consider- 
able size of various kinds of rocks were scattered about, 
and among these were masses evidently derived from the 
sinter of the terraces, and, from the manner in which 
these fragments appeared to occur in quantities where the 
finer dust had been blown fro the surface, it is probable 
that the lower layer of the deposit will prove to be com- 
posed of coarser material than the upper. The boundary- 
line of this dazzling white deposit is very distinctly 
marked. It can be well seen where it passes over Kakar- 
amea Mountain, dividing it, as it were, into two portions, 
one white and the other green. While traversing it we 
experienced a great downpour of rain, which formed the 
powdery material of the surface into little pellets ; but it 
did not appear to be very absorbent, or to show any 
tendency to work up into an adhesive material. This is 
very different from what may be termed “the grey 
deposit ” which is next to be mentioned, and which covers 
the country, from about two miles south of Wairoa, in a 
northerly direction towards the Bay of Plenty, as far as 
the Te Puke Settlement. This is the mud-forming depo- 
sit, and wherever it appears to have descended in a 
thoroughly pasty condition it coated the vegetation so 
heavily as to break limbs off lofty trees and to crush the 
smaller scrub flat simply by its weight. The sand, as 
already stated, appears to have fallen hot, so hot, indeed, 
as to set fire to the trees, the stumps of which were scen 
burning in many places; but there is nothing to lead us 
to suppose that this grey mud when it fell was even 
warm. 
“Tt has been suggested by some that this moist deposit 
was mud thrown out from the bottom of Rotomahana 
Lake ; but it is difficult to conceive how, in that case, it 
should have overleapt a strip of country four or five miles 
wide, where there is nothing but dry sand, before it 
reached Wairoa ; and I think that a more likely source 
for its origin is to be found in the sudden condensation of 
the front edge of the great vapour-and-dust cloud when it 
suddenly met the violent cold south-west gale which 
averted it from Rotorua and directed it towards the sea- 
coast, where it spread over the sky and caused the 
darkness that was experienced at Tauranga and all over 
the country to the eastward. The great volume of this 
dust-cloud was directed towards the East Cape, dropping 
over the country in that direction a comparatively heavy 
deposit of brownish-black dust, so coarse as almost to be 
sand ; while on its northern edge, as far east as Tauranga, 
the dust is of a light grey colour, and excessively fine in 
grain. A collection of all these different deposits has 
been obtained, and will be reported on as soon as the 
chemical analysis is complete. The impact of the moist 
deposit when it fell must have been very great, from the 
effects which it produced at Wairoa, where it appears to 
have attained its maximum thickness of about 12 inches 
in open level places free from any influence that would 
cause it to drift ; on the flat spur above the bridge at the 
outlet of Rotokakahi its depth was found to be g inches, 
and in the Tikitapu Bush 4 inches; and from that point 
it gradually decreased towards the north. The action of 
rain upon this mud rapidly converts it into a semi-fluid 
condition, in which state it slides off the hill-slopes and 
fills the low grounds and watercourses; and where it has 
been thickly deposited it will thus be a constant source of 
danger for some time to come, but where only an inch or 
so in thickness it will, I believe, rapidly disappear, and, 
excepting that it may for a time deteriorate the pasture 
and destroy the existing vegetation, it will in the long run 
be an advantageous addition to the light pumice soils 
upon which it has been deposited, owing to its slightly 
absorbent properties. As for the light deposit of dust, 
which fell in a dry state, there is very little doubt that it 
will be all washed off into the soil with the first heavy 
rains that come. The distance to which this fine dust 
NATURE 
[August 26, 1886 
was carried was very great, exceeding at least 120 miles 
from the focus, in a direction between north and east ; 
and the time it remained suspended in the atmosphere 
was at least eighty-four hours, as we passed through it in 
the A/znzemoa when crossing the Bay of Plenty on the 
Saturday afternoon, as a peculiar yellowish fog, charged 
with pungent acid vapour and dust ; and on the following 
afternoon we recognised the same fog-cloud still sus- 
pended in the atmosphere towards the north-east. 
“WV. The Evolution of Steam.—The enormous volume 
of steam rising from the site of Rotomahana Lake gives 
rise to a pillar of cloud that is visible in all directions 
over the country, having a diameter of about an eighth 
of a mile, and rising to a height of not less than 12,000 
feet. Its effect is most impressive, especially in the 
morning and evening, when it is lighted up with gorgeous 
tints by the slanting rays of the sun when it is below the 
horizon, and all the surrounding landscape is in twilight. 
Although this steam-cloud receives rapid additions in its 
lower part from successive explosions, these do not gene- 
rate any rapid movement through the mass of the cloud, 
so that, if viewed from a distance, it appears to be almost 
solid and immovable, except the changes that are gradu- 
ally effected upon its lower portion by the movements of 
the atmosphere. 
“VI. Lhe Propagation of the Earthquake Tremors.— 
Earthquakes are the usual results of the violent con- 
cussions attendant upon violent outburst, and they afford 
the only clue which we can possibly have as to the depth 
below the surface of the earth at which the volcanic 
energy has been exerted. Thus, if the earthquakes are 
felt with only slightly-decreased violence to great dis- 
tances from the focus of disturbance, it would indicate 
that the disturbance is a deep-seated one. On the other 
hand, if the earthquakes, although extremely violent close 
to the focus, are only felt at a moderate distance, the con- 
clusion to be drawn is.that the forces at work are only 
superficial. All reports agree that at the Wairoa, about 
four miles distant, which is the nearest point to the 
eruption from which any persons have survived, the 
shocks of earthquake during the first phase were violent 
and continuous ; whereas at Rotorua, twelve miles dis- 
tant, they were comparatively slight. The great earth- 
quake at the commencement of the second phase appears 
to have been felt with considerable violence at Rotorua, 
and distinctly arrested attention for a distance of at least 
from sixty to seventy miles, but does not appear to have 
done any damage. 
“During our visit the earthquake shocks in the vicinity 
of Rotomahana were still frequent and violent, but at 
Rotorua they were only experienced as gentle undulations ; 
and I ascertained that they proceeded from the effects 
of the explosion from the Rotomahana fissure, and that 
the eruptions from the summit of Tarawera, which were 
clearly visible from Rotorua, did not produce the slightest 
apparent tremor at that distance. A few insignificant 
earthquake-rents were seen crossing the flats south of 
Kaitiriria, but only where there was a drop or unsupported 
bank. 
“VII. The Sounds.—The sounds produced during the 
eruption must have been, from all accounts, appalling to 
those within a moderate distance. The crackling thunder 
produced by the electrical discharges, the terrific roaring 
of the high-pressure steam escaping through the volcanic 
vents, were combined with terrifying effects. Much has 
been said about noises heard at Auckland, Wanganui, 
and other places. From the times mentioned, these 
appear to have been due to the reverberating reports 
accompanying the Tarawera outbreaks. Some of these 
noises may have been propagated through the atmosphere, 
and reflected to the earth from the under surface of the 
stratiform cloud-sheets that were widely spread in various 
directions over the colony on that morning. Others, 
again, may have been propagated through the earth. 
