THE VOLCANIC ERUPTION. DR. HECTORS REPORT. (BY TELEGRAPH-PRESS ASSOCIATION ) Wellington, Monday.

Te Aroha News, Volume IV, Issue 160, 10 July 1886, Page 4

THE VOLCANIC ERUPTION. DR. HECTORS REPORT. (BY TELEGRAPH -PRESS ASSOCIATION ) Wellington, Monday.

Dr. Hector's report on the recent eruption was laid before Parliament to-day. He Bays :—: — Tarawera a Volcano. From examination of the slopes of Tarawera I conclude that the mountain is really one of recent volcanic origin, belonging to Yon Hochstetter's new volcanic Series, and that its abrupt outlines have resulted from fractures and subsidences ot its flanks According to this view it ia natural to assume that the still impe) fectly # cooled mass of lava in the heart of this volcanic mountain haa given rise to the long-continued (historically speaking) solfatara action at high tempera tures that created the attractive wonders of Hotomahana. Jt has been stated that no native tradition exists of Tarnwera having been the site of previous activity, but the range culminates in three distinct peaks, the meaning of the Maori names of which according to Mr Locke, M.H R , and other authorities, clearly contradicts thisasbumption. This consideration has interest, as a sudden development of volcanic activity in a new locality, or in an ancient and greatly denuded formation, would have been more Serious and significant than a mere tempo rary revival of expiring energies of a rtcent focus of volcanic force. Tne Great Fissure. This is the most remaikable and characteristic feature of the late eruption, and the chief origin of the disastrous results which attended it. A good view, but much -cbsc-reri by o-wiu, -was obtained from the hill called Te Uapa o Toroa (altitude, 2,300 fett). This fissure seems to commence •aa a narrow rift at the northern end, from the great rent which has been formed in the South ond of Tarawera mountain. Tho rent is 9 most wonderful feature. It is not a slip from the mountain eide, but appears a3 if a portion of the mountain, measuring 2,000 feet by 500 feet, and 300 feet deep, had been blown out, leaving a ragged rocky chasm, from which steam was being discharged in rapidly succeeding puffs. The eastern pido ot this chasm was brightly tinted, ns if by the efflorescent deposit of a mineral substance, probably ferro-chlorides. Sulphur has been Mentioned as a deposit from thU recent outburpt by some w'no have witnes^eu :.t,: .t, but this i^ hardly a possible result of such rapid volcanic development. The direction of the fissure, as far as could be ascertained, is in the general line that wuuld connect all the more active geysers between Tongariro and Y\ hite Island. Matter Ejected During the Eruption The quantity of matter which was ejected dvi ing the different phases of the eruption was very large In the first place, Stone fragments were scattered from the earlier eruptions of Tarawera over an area of country extending to the eastward a* far as Tekoe, atid even, some say, to Fort Galatea, while in the opposite direction they are not reported to have fallen at aiiy place farther irest than Wairoa, a distance if six miles. None of the fragments which I collected are other than portions of rocks of the district, nor do they present in the elighest degree the character of volcanic, bombs or lapilli, formed from lave or rock material in a state of fusion. Yet there can be no doubt, if we can accept the evidence of eye witnesses, that these rock fragments o.dt=t hays-, ie ;D-di6 cases, reached ihe ground in a partially incandescent state. Next followed the great ejection of pumice sand, which forms enormous deposits in two localities. The one is on the eastern slope of Tarawera mountain, already described, the nature and origin of which I had no opportunity of ascertaining, The other deposit of this nature is chiefly on the western si lo of the Rotomabana fissure,and wasno doubt ejected at the comnaencement of the second phase of the eruption. Over a district of 24 square miles south of Tarawera lake, and on an almost equal area to the north and east of the lake, ihe whole surface of the country has been covered with this pumice sand, to thickly as to obliterate in a great measure the natural features, partly titling gullies, and enveloping all the hilla as if with a deep mantle of snow, so hhat not a trace of vegetation can be seen from the highest peaks such aa Te Hapa o Toroa, whicn is 1,300 feet above the sea. Down to the level of the lake the thickness of. this ds r% Goi« could not be ascertained at the time of my visit, as no slips had occuired in it, and no sections were to be seen. It consisted of fine - grained and gritty pumice sand, slightly crusted on the surface by the action of the rain, which also caused it to aesume a slightly greyish tinge; but underneath it was a pure white, and at a depth of 12 co 18 inches from the surface had etill a high temperature on the sixth day after the eruption. Lying on the surface of this deposit, especially on the slopes directed towards the fissure, fragments of considerable size of various kinds of rocks were scattered about, and among these were mappes 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 from the surface, it is probable that the lower layer of the deposit will prove to be composed of coarser material than the tipper. The boundary line of this dazzling white deposit is very distinctly marked. It can be well seen where it passes over Kakaramea 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 f)owdery material of the surface into ittle 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 the one 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 deposit, •nd wherever it appears to have descended In a thoroughly pasty condition it coated the vegetation so heavily as to break limbs off the lofty trees, and to crush the smaller scrub flat simply by its weight. The sand, as already stated, appears to have fallen hot, bo hot, indeed, as to set fire to the trees, the Stumps of which were seen burning in many places. But there is nothing to lead us to suppose thatthisgrey mud, when it fell, was even warm. It 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 oyerleapt 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 sodden 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, ftnd directed it towards the sea coast, where it spread over the »ky, and cftttttd ib« darkness that -mi experienced -jft

Tauranga, and all over the country to the eastward. The great volume of this duat cloud was directed towards the East Cape, dropping over the country in that direction a comparatively heavy deposit of brownish black dust, so coaraO as almost to be sadd, while on its northern edge, as far east as Tauranga, the duat is of a light grey colour, and excessively fine in grain. A collection of these different deposits has been obtained, -nd will be reported on ac soon as the chemical analysis is complete The iinp-ict of the moiwt deposit when it fell must have been very great trofn the effects which it produced at Wairoa, where it appears to have attained to a maximum thicknec-s ot about 12 inches in open level places, free from any influence that would cauee it to diift on the flat*, for about the bridge in the outlets of Rotokakahi its depth was found to be rine inches, and in the Tikitapu bush four inches, and from that point if gradually dcci eased towards the north. The action of rain upon this mud rapidly converts it into a eerni fluid condi tion, in which state it elides off the hill I slopes and fills the low grounds and watercourses, and where it has been thickly de posited it will thus be a constant source of danger for some time to come, but whore only an inch or so in thickness, it will, I beiievo, 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 h.is bs£n de- ! posited, owing to its slightly absorbent pro perties. Ac for the light deposit of dust which fell in a dry state, there is very tittle doubt that it will be all washed off into the soil with the first heavy rains that come. The distance to which this-du-*t was carried was very great, exceeding at least 120 miles from the focus in a diivc tmn between the north and east, and the time it remained suspended in the air musr have bee ". at. lea«t S4 hours, as we passed through it in the Hinemoa when crossing the Bay of Plenty on the Saturday after noon, as a peculiar yellowish fog, charged with pungent acid \apour and dust, and on the following afternoon we recognised the same fog oloud still suspended in the air towards the north. The Evolution of Steam. The enormous volume of steam rising from the site of Rotomahana Lake gave rise to a pillar of cloud that is visible in ail directions over the country, having a diameter of about out>-eighth of a mile, and rioing to a height ot not less than 12,000 feet. Its effect is moat impressive, effecially in the morning and evening, ttueuiuio li^htSC* «.p with gorgeous tints by the slanting iaya of the suu whuu it 1 is bulow the horizon and all the arrroundiug landscape in twilight. Although the steam cloud i eceives rapid additions in its lower part from successive explosions, these do not gm.eiate any rapid movement through the nja-s of thia cloud, so that it viewed from a distance ie appears to be almost bolid and immovable, except the changes that am gradually effected upon its lava poitiou by the movements of the atmosphere. The Sounds Attending tne Eruption. The sounds produced during the eruption must have been, from all accounts, appalling to those within a moderate di&tance. The crackling thunder produced by the electrical discharges, the terrific roaring of t the high pressure steam escaping through the volcanic rents, were combined with terrifying effects. Much has been said about the noises heard at Auckland, Whaneanui, and other places. From the times mentioned these appear to have been due to the reverberating reports accompanying the Tarawera outbreak some of these noises may have been propagated through (.he utuunphere. unu re fleeted 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, but I have been informed that at the whaling settlement at Tawata, on the east entrance of Tory Channel, from six p.m up to about eight p.m. on the evening of the 9th (the night preceding tho eruption) loud booming reports were heard as if through the earth. As these reports were previous to any symptoms of the loud disturbances at Tarawera, this suggests that they may have resulted from a slight movement along the great fault lines that traverse the North and • outh Islands in a northeasterly direction, and in this case the immediate cause of the Tarawera outbreak may be found in a local fracture, and resulting from auch movement. Premonitory Symptoms. The report? of sympathetic outbreaks '" other places along the line of volcanic enorgy, from White leland to Ru-»pehu, appear to be quite unfounded. The outburst has shown conclusively that the springs at Kotorua and Rotomahana are quite independent of each and othar places, thus confirming the observation made by Yon Hochstettor long ago, that all the various points at which thermal springe occur are situated around the margins of lakes formed by subsidence of circular areas, and are not connected by an underground system of gravitational drainage.