THE RECENT ERUPTION.

Te Aroha News, Volume IV, Issue 162, 24 July 1886, Page 8

THE RECENT ERUPTION.

luteresting'-Paperß^ $Lt >.§, .meeting of^^i^n^h^j|Dßtituse s jn»-ithe; t -MueW^j:^^ .i;£pbser;!^ > y Smithiread ; ; the;: flrat?^^part pf;theipaper?andv^j^.i Pond the second.? The opening chapter described; {the voloariib kories;:Ethe 1 /flret r| from Tongarlro' ftfo ilsian^ ; f tj^ iAupklapd;; the. tjHrdj that pf the Bay o t lsland^ SHev^said; the : flrs^named was; the f; ? orilv brie^in whiph any eiterit^of vitality appeara 1 to' haw reniainfed.untio^thepres^tjdayithda^h'thefßayJ. cf Island dif-trjtot has still its group pf hot springs;] , whilst the Aupkland zone, so intimately known' to all of us, has oeased to eKow ariyißijrn of life ■ aty all, though exhibidri^?«i6'the\ppserver:spmel'of! (he moat perfect ;examples of extindfc vblcanici aotion in its sevt-.ralsißges knpwri to ,the world. Toe rocks of the central Iqir* Taiipo zone* are composed, of materials known, generally?urider the' name r--;of < acidic rocks,- (whilst those of the ptJier twozoiiesare-r intheiclHiteatmanifeatations at,ftU events formed 6t basic rocks. -We may take as a general name descriptive of these! t wp Classes of rpbk— traohy tic' * rooks ' fpr the! , acidic . areas, uaealtip roeka tf or thot e of ■ the basiol areas— the diatinction'beipg in the nature of the ! constituents and thur;Xb ms pf : *aggregatibri. : The' researches' of modern science tend co confirm the idea that there isafreeuiar sequence in' theorder in whioh .these: fwpol«Bses pf rpek are ; tjeoted „frpm volcanoes, the acidic pri traohytio; 'denotib'K'the'eaifli^r; "'-. the basic or <■ basaltic * the* later^ stages*' 5 -of' v-vol-i canio; i.1ife.,,. •; /. Thera... 1 Lare.:ir)r^well M kribwnl ("xcepdons to this, general rule, .hut taken as a> whele. the s 'etid6nce^^^.teridß"tp"shpw tHat'subhis! the life history of most volcanic i districts.' ' 'Itr may. be that soriie fyoloanoes commeribe their! ,qareer,,pyi,_the ; i e d e 9tiß n iß'bi^idipmaitier.j and! continue thrpughQU^ , the 'l whole cpuree; up * to? their final extinction, terinjnaiirigin the ejection' of , bilsftltip mattar.v^ithput material inter--ruptibn 1 of their^actiyityr^wnilst* ctliersr ? after; making a commencement/are quiescent, or only partially active for ages, remaining in the a^cidto; stages for such lengthened periods that volca"; upas, which can pc shown to be far younger ri ia actual age, have* had ' 'theif^day, 'arid become; extiiiot. ,; Suoh eeema,xp.bß»the c^sewith the' 'faupp, or central zone, It is" still in the acidio stage, while the younger volcanoes ' of ! the ; iattiinua appear to, have run their full course aud become extinot. ■" •'• . : •; N - - !! '■'* „ Mr cmii-h described , 4 very fully the; central vblcahid 'district of tne* island: He said New; Zealand had been colum'dt.d. so ahorc a^ ttmui cbniparod with the geologic ages of the past that observation had- not ye G been continued sufficiently long to record any great changes in. the 5 Yol.Panio regions .alluded ; to. It anythiug. a general opinion . had: been .current to tne ' effeot that' -th'e forces have been decreasing in activity" rather tnan the contrary, and Maori tradition; Urit weight to that im-preat-ion,. They, had jn^ny of the greater activity pf the hot springs, but nbno of their legends spoke of any greac'calanilty having"" be-] failen their ance.-toro through' volcanic agency, and we might be Bure that ampugst a. people who were so Bcriipuloutly careful in handiDg their' history:," any 'great catastrophe would : have certainly' been rioted. Mr, Smith thougnt a "consideration, of some few, ocourrencdS _: in that. , .distriqt .during the twelve months, and immediately preceding the eruption, ought at least to 'have warned us that Home changes were goinsr on, a few of which will.be noted." , Some notes of symptoms of greater activity, eeeu by Mr. Jqai*h Martin when VlsitinK the f erraccs last summer, were tiu n read, and also by Mr Laurence Cusaen, as to the greater activity lately observed at Tongajiro and Ruapahu. . „ : . . Effect of the Oscillation of Mars. The paper then' proceeded:— "lt will be remembered that on the evening previous to the eruption aa ocou ! ation of Mnrs by the moon occurred 'at twenty minutes past 10 p.m., the moon being, just then entering her second quarter. It would be high water on >he coast near Maketu that evening at about, 10 pm. We do not give much importance tb these facts, but it is' worthy ' of note that the ' well-known theory of the tides, assumes that the waters of the ooeau are, at high water, piled up, as it were, on that particular portion of tbe earth's suiface which is just under the moon, but through friction and the counter attraction of tha sun that tidal wave lags after the time of pa -sing of the moon over any particular meridian. It is equally a part of this 'heory that the solid materials of the earth are at the same moment subject to a wave, muoh more limited in extent, bur still appreciable ; and : it is well, known that an atcaospherio wave passes round the earth at 2 o'olcok each day. Hence, the cruse of the earth being in a state of tension, if there is any predisposing cause tending to a fracture about the period of this .earth wave, it is a natural inferetice that the conditions are then: most favourable for' the' production of such a fracture;, The attraction of the planet Mars added tv that of the moon may be,, and no doubt ib, very Blight ; but the fact'remaius that, whatever influence the moon may exert at any par-' tiauiar moment, it happened to be greater by the Bum of h»r own and the plane ta very shortly before the eruuti.n ", r .'... Dr. Hector's Local Theory Challenged. ' " It has been stated that the eruption is' quite, local in it* aotfon, and goes to prove that the series of hot. springs in different places, and other" signs of volcanio action in the central zone, are separated' and have no connection or syiuDathy with one or another. A considera- . tion of the following facts, relating, to events which occurred at the .time of the ernpiion, or coon after, pro to prove that, srioha conclusion; has h^ea drawn from insufficient data. Allusion has already been m&<lo 10 the activity of the creator on Ruapthu-- .New.c haa.reachea us' within th« last ''t**r days which confirms a. report brought to Rotorna by Te Heuheu, the. chief Pf Tokaanxi, at the south end of Taupo Jiake, that Tongariro, or ra^re properly Ngaruruhoc, was much disturbed on the night of the eruption. A roud party' under ; the charge of Mr A. B. \v right -„ was . encamped on tho Poutu river, just a few miles north of Tonga 1 iro; they -, were awakened by htaiDg "a great , rumbling, and a largo-numbor pf sharp detonations likethe reports of cannon- proceeding from Tongariro ; vivid flashes of lightning play c t around the summit all night and early tne following moruiog, and 'every minute an' eruption' was exo' cted. Strange to say. 'however, no earthquake was felt. . The springs at Tokaanuwere, npt apparently effected. Next we call attention to the greatly iucr eased aotivity of the springs ftfc'Rotdrua A snlill Bteam fumarole, which' in its ordinary 'state was only occasionally visible, near the Government agent's house, became a large bpi ing sprii g, about ten feet in diameter, from which a Rood-sized stream of het water ran away tpwards the lake. Further north, at thn base of the Pukeroa hill, and in the direction of the Maori village of Ohinemutu,; S^eam came forth from innumerable cracks in the earth, somPtinaes accompanied by hbt water, whioh formed etreams running al^ngaido the road from the old to the new township, and iv the pa itself a sprl' g burst out iv the. great .meeting, Ihouse of Tamate Ivapua; another in the path, leading down to it; and yet another 1 just behind the building. : All of these outbursts 'occurred' on the night : pf the eruption ; they./all, follow, however, the old deposits of sinter at; the base ot the Puk'eroa hill, the laat remaining signs of former great aotivity in that locality. r ;The activi tyb' the vaai number of f umaroles and springs in «nd around.Obinemutu was certainly grehtvr than usual a few.days"after r the lOih." : The level; of Rotorna Lake oscillated somewhat oh tho 10th June, but to no groat- extent: ; At 7 a.na. it fell one inch, at 9 a.m. it rose sis inches, and ft?ll again at noon three inchep, a«)d remained bo all day, falling- on the night of the 10th five inches,' since when the osoiilatibri has been bontinuoua, but to no very great extent The temperatutepf Rachel's dpring at tha'Bftnatorlutn on 11th June was 170°, arid; from ithat date^ to "Ist July it gradually- roße ' to 'We 0 , 1 ' with a greaterflow .-than before. 'For,; these exact data we are 'indebted ; to .Mr Bpscawen, who obtained them from Mr, Hall.the observer." Mr ymlth next referred tp the' greater aotivity obaervefJfat.xyhitoflsland : and in" the large group , of springs BUth of Kakaramea, in the direoc lino of the great fl3* > Ure; ■.; ;:'A .rtet-iiled description of the p'oirita' of vaß then, given, and also of the pharabter of : the mat-jrial composing .the;ejeotad;tnatt.er.' s--"- 3th ' -. „;;■=".--.*.- --■ .* : '- —•-•>-^ : ■r.VV'V-'Pertili^y/.^f Ahe;iaectea; Matter. /■. *• ; "The mud arid ash deposits at Okaro, Wairoa, Tikitapu, and- Tauranga. are, , very vßimilap! i a appearario^, beirig cbriippped very, largely , pf sllioa, both in the elieey solid , crystalline ;form and as ßihteri'together.with: a smallbut varyiDg :proiiortlori!Ofrscoria:tQopiing,next.tothedepowt at Matata and we, ; |lnd. the m the same f6rm?r ; but -the jßcorlavhas jncreaaed ,' ! -iH^prb^irtioh;"* Ad vdnoing-: still, fuctUer eass^ard to ? flndlhe Bamo dharacterlstlcp, ;'i but.'the -: Boot ia^ h?B etulTurthjfr. .'ln'oreaßed ? !"iii^HtsSpVoDorU3ri':t6\theiunooinbiried:.' -niade pf :thema;^?^l^b^ined^ron^ ; ; me'ritibriedliwb;(flrid>that;|the^^ re^ulia pfiburJbptibaVexa^ *a%&frorafOkara^VVairpßT|aittd*Taurari^ fthe'Mldib Krburii^whil^thPX^ 'and^Opp^ki^reiniora ; baeio^ @S^^^h^^o^bVj^n!»^wmf

'Moii -:Hoohßtet^r%?the members brtbe'KSblo^ fOa'listafr.qtpuiJooloriy^ ; '*9j sh?i&?S9*v*\s&sKQXjlavgo qaantit jes.6f jbasaltt*;^^ or^ mount^n! at theearlier'- ateges ?oi 'th# ? erui*^ ' : tion H;6nV ■ thefiriioniilriirtot^ the l?di]Mft& ' - I Thiaiis fully^OTne;oupi]^t;he;^me^B^oy^ : J> witneßses, who -jUnanimQusly ispeak OC oolumnß ft df fire rUfehiDK-uij from the newly-foraie'd crateiv '^ and maaßes office^ bufstlng'andfalling baok^aw ' ! f around the i>ideß|bf pthe mburitam.^>T.hßtvthßWi ; molten; : ;ifty^jpjtoeqailyH«l»:-*: :: cernlble after;the:night indu^ abl6^Dysthe/JBnprtoo^V.rii6n''pf presstTO^" ■ Bte'am?:j[darryiAg - off/the molten 'mats maifliio ' atefe^tttp the f air;-; where;- ic , was i carried a^askpy£the f strong rSy^^^d^w^iofi^hadnfnrar; .commenced. : to- blow;^ or-'* by* .^being' doverell. up by i the ,' bu osequent: of ' asholw i We .see Jtfjmiu , ttev. f6regbi»K ? ithat hay* , W d 4^ d i \?MM;^ u Pttop,jthe ORe ( vhydrbth©> ,mai;;]the oth^r" Voicanfo, tn>owi'ne"dut diffei^fe tpoks; acidic and" basib.'ffie.toHyßfeardharaoteJH of these ro6ksbeiDg as different as their schfl* ''■■> mjcal qompoeition; -to a great, heiorhfc. they were caught-by the. wind Btorm, and borne along 1 By it in ' parallel lines f rom whence -tfiey emanated;! : the >aeidi<j ltd i the westward,' and th« basic to. the; eastward,, andv but slightly com- ' mingled. In;this,prdeß-they} j adyanced, and .in ' : this.' prqer' Were.-'cprepipita'te'd. on the landa /over' wluoh they^'palßed^^'Goars'e" sand^flneip TParticlesV^ dust^thua - : it Hwaa .'.- laid, riin; f.thtt I .order mpet to be f . depired; by,, the, agciculturlflj^, So "; n,ne, 1 v indeed, ■ is* . a -large : portiop 'Tot. tha deposit, that ! the elemenfo of riutfitibri if v it ar«k available for; vegetation^ almost aß'soon'as'tiHa .first rains have carried it into the aptl, 'while JtJiQ particles not bo exceedingly fine are,a&eady.,b»« ing" attacked by : that wonderful disiritekrjitoft, carbonio aoidiPdr -a moment let us glarice^fit rthe basaltic lava iirii;:the> vioinity ;S«r A uc^l an d, ; jhere u wja^findjthe.jrtohegfe land, .capable growing; "extensive / pro|£ T6e ;iridre' deebmposea^ the finer' ttie partiSlei, the greater the , ambunfeni'ofartaisihtegifcl tipiij;;; the 'l richef *; the, t ground,, the ;j greater the prof usioii ' " of v'thS I '-■ elements i cf ot-f^ f ertilits: liß '■ thalmkterlaP which' has befitim slavishly ■ spread: overi the land} on< the ; ;ea9terii portion, of the. district., and which is so largely intermixed with the* aoidlo' matter whloh has falleflover the we'Bterni":'Th'a\P thfi'r6'6K r fai fta uhbrokeE;:ußdeco,i)poßed! formula nearly valufe\m 1 1 W tV}m%i)^, '«Wfi ;oan>leam bystnrnijigp,^ •the baealUo floes and, cinder deposits of Rangl'tb'tti ; v but o 6Veh'tli^,;in r'th.eifew gullies'whewi r-iin -has wa'shedf the 'dust^and given^depth of friable jgoit for -plants /,to> Jiyejin,tiw6^w^l see a richer ;,profusioA ( of AThe r refiult of this downpour over so "large, an; area, need hot 'disma^^/'But^rather^glve oaUßfi^W* rejoicintf that in .the; majority, of ■ instances! :a richer soil, has ■ ;been H added than ; rormei;iy existed ; and so lightly and finely has it fallpa that' the winter rains wiU'not have passed Hef bjcj» it will have^ heeif washed into the soil to-ia-vJptorate .the-, new yegetatips and improve tbja pastures, except in. oloße Droxlmity to the Been© of ' th.'c . eruption. Even here we ; Jiaye 1 gh'6^rn. that these deptisita are capable of 'Bupp'ortliig .vegetation." ' The nexti aubject , disouaaed was ] Probalile Cause;Of tae.Eruptio^ay} . The paper prdceeded r to hazard as la Buggeßtion.'of ithe probable t cause .the; action at) th& thermal sprjpgs, around. Rotqmahana; carrying away ah imriiense amount "of .mineral matter, leaving 'cavernous 'spaces and a weakehirigoC the earth orust locally.^ If then we bear/*ltt mind the proximity of Mount., Tarawerflk, towering to a height of oyer 3,000, feet, we hava a source of danger that must make itself felt sooner or later.' AfrTen'ath" we' >cay presume that the weakened honeycombed rocks were unable to .resist .the t enormous presoure of tha mountain, a portion of the ba3e,bf which fell in at a place nearest to th> source that had sapped it. Possibly ■-' this "■ effect may have been precipitated by ; Bomexslow raoviDsr earth, wave, evidences, of whioh, wehave already adduced. We have ' now ample cause for. the in>mense rift on the S.WVsid* of Taraivera, aa tha effect of. the . watera from Rotomahana rushing into the chasm and comicg, into contact with a, large surface of molten .rock" would bo followed by a terrible convulsion, the Scaping' ateana ripping up the side of the mo an tain in the manner already described. :< The sudden bursting of the overlying rocks woul,d be also followed by theejebtmentof volcanio matter, Which had beetk. molten but dormant at some ' distance beneath, it s. base. Again and again would the -water rush, on the heated rock s, on l y to be driven back and. diasipated into tte surrounding spane, touethee with the fragmentary matter and dust resulting from the shock.' The water from the lako would thus be driven up. together with • the steam and debritrc masp, to fall over long distances in the form of mud, as wecowseeit.until the water had biitn expelled from the lake, and with it all: the Bolid material resting on its bed. By this action the bed of the lake has beea lowered an X its sides greatly extend d, wbila there can bii little doubt that the whfiie of the Terrace formation has been b wept away. That* .thid long dormant molten m&ss of lava undeis lying the mountain extended no fu< thcr is very ques ionable. find the eyidencespf fur. her extension in' a south-west direction are sho wn by the length of the rift extending to! tbe Rotomahana thence by its eu tiro length, and finally, prooeeding in the direction of the Okaro Lake for abOTft a mile. Here we find \tf effects very violent, 'the five active craters alraady deyeribad not being built- up,;but,blqwi» directly out of the rhyolitic rock. In reviewing the weakening of the rooks bysoluable matter, withdrawn in tha waterd. Ip is difficult; to arrive at anything lika accuracy in regaid 10 the amount of 1 water discharged. , If, however, we take the effluent, tha Kaiwaka stream, as a n'.ean depth of 2 feet; and a width -of 25 feet, flowing at the rate of three miles per hour, we have *9 tnillloik cubic feet, or 80 million gallons, in 21 hours. If we vow estimat) the solid contents of ona million gallons of water, cpntainir g loigraina I per gallon, we obtain nearly 10 tona as tha result, and this, multiplied bytßo million gallon*, will give a total of 800 t tons, of solid water. If. ho wever. we only accept one half this amount of water as beiny: aischarged ! from tha springsv tbe final reau lt gives- 400 tons of took material withdrawn iji ea-h.iday. , That the a9&umplioa of half the wat<;r being discharged froaa tha springs is below the mark, the heat of the lakQ and its effluent pave fail proof, aa well as tha small aaionnt of water which entered by ita tributaries.": The. paper concluded with the following remarks on the , , '. .

Probable. Effects of the Eruption* . . "From tne results" whloh we have been boat* Rid eriog, if -viewed in connection with Jtha theory advanced aa to the cause of the: rerun* tion, we can venture to . surmise the. action which willtake place in the future in this arid the' surrounding di3t icts. ' As ■we have already shown, the eastern part of the Rotomahana valley has btea overlaid, with a, deep deooeifc of, stones, sand, arid mud, cmtil thft efflaent of 'tb'.e lake haa been entirely filled up, and considerable mounds of the oeposlt stand : above this : pain, beneath which tha river ran into, the Arilti. At , the samo time a moat all the wafer previously in the Lake has been "dissipated. At preßent the ■waterlying in the Okaro Lake tfs not beins added to, owing to the immenae amount of dry y shin ita vicinity, which absorbs the rain as it, falls, and the samn remark apolies to the .emirebarins o£ tha Ro omahana. Until the po'rit of the satura'ion of ihls material has been arrived at the present state of pejser action wil he very slightly olteteo,- but.' after- this period the ■ gradual inflow of water into the basin will Qa folio wtd by iticreased activity o( geyser action , until the maximum wii 1 be reached by the Waters covering tbe present steam outlets, owing: to the barrier at the outlet of the Lake. We may anticipate' now that' large maeses of wateb coming into contact, with, extensive surfaces of highly-heated roc'-s will cause a succession of intermittent geysers grander .^tid more extett•five than arij thing of the kind known in Ihia part of the world. It is probable that this will continue for a long tirae, unless the barrier ,oC Te A.riki is Drouth down by the pent-up water, when the present state will be resumed. ; Under any oircum3tarice'9, "we feel : confident : thajt with the cradual Jise of waters over ; tha . floor of the Lake, the sealing or th^ prosdnt outletH which will take ,, pHoe, witt give riie ! to greatly increased aotivxty in the imuiediato viciiiiiy. At the; same time, there is every reason to anticipate that theeffeota will be extr <mely'l6bal, ; beyond earth tremors and flnoall shocks.' which may laßt for a 16ns period and extendbeyoud the district./ Already we have stated our •oqrivietioa, that... Tarawer* and the Thermal .springs in' its neighbourhood are asfociated with, and in actual connection with those of 'Kaka^apae'a; Paerda,arid>pro^ bftbly witK: p^nemutu;-,; Assutuing this^to^be the paEo, that from the Bame mass < of moltea matter all these springs* emanate, tha late eruption will have so 1 eUe-y;ed any pressure iri^ther directions that tboteie hardly;any danger for a - very long-period of serJpuß manifestations of & like fjhaTac ter in any bf these localities, . in fact the reverse iriay be'aritiqipated^thefjradual a^ cafletioepftheihoKspririgsofsttie "districts arid : Iheirconceutrationiat Tara,wer«u'*T i; 3 Muph interest was diaplayed by those preßent 1 iri ;ihe iri^ecii'ofc^ •iricluaed "scraßse's^KrpwifiK'. Iririlud ! depoalwa Dj the (Muptipn?eihlb;ited'by;iMr Pond. ;? . ■ ; \w,- ; . \i' : lvP©ftr>y;^ i h;fts <^a^9^fi9turiied,^to the gentla- : pirepared,t^ -■' - : rJ-'. l t/?-""y ; ~-