NGAURUHOE.

Dominion, Volume 2, Issue 487, 21 April 1909, Page 8

NGAURUHOE.

"GREATER ACTIVITY THAN EVER."

EXPLOSIONS AND SHOWERS OF DUST.

[ (by TELEaRAriX— FRESS ASSOCIATION.) / ' Auckland, April 20. . Ngauruhoe is stated to be in greater activity than ever.' Yesterday, in,addition to the eruptions of Ngauruhoe, the wholo of the Tongariro Plains were alive with thermal excitement, dense clouds .of steam rising from To Mari and. the Red Crater, and also from Ketetahi Spring. Then-about eleven o'clock the volcano poured a mighly volume of heavy smoke .several thousand feet high, while dust was discharged in dense shower after shower over- Tongariro and on the Waimarino side. For nearly half an hour the mountain, thus laboured and convulsed,' roared and rumbled the while Tvithin its depths so that , the noise and tremor of it was appreciable ten miles away. Tho previous night,' it was stated by-the groom at Mananui changing station',' was marked by more disturbances and explosive noises from the mountain, than any time sihee the outbreak.

LINE OF DISTURBANCE. _ Mr. R. Speight, T.G.S., of Canterbury College, states in a report on the geology of the disturbed region:—: ■ ' . , ■ . The similarity in the mineral composition the lavas and the linear arrangement of the centres of activity point to some' deepseated cause aftecting the whole'area. No '?? t-a line of weakness in tho earth's crust extends m oni approximately straight lino fromjßuapehu through Tonga and Samoa todistant Hawaii. This line may perhaps be called the 'Maori line' of volcanoes, as no doubt the first Maori immigrants to the country followed its direction more or less closeh;, and tho legends of the Native roforence*s which show clearly that.they recognised the linear arrangement ?f vents and their common origin. Ac-tivity-u more pronounced now at the northern end of this line, perhaps owing to the ct .that another earth-fißsuro crosses it, running west-north-west arid east-south-east —i.e. ( approximately at, right angles to the Maon line. The_ great volcano ,of Savaii, in bamoa, is placed at their 'intersection, and hence, its continuous activity for the past few years. .The Hawaiian line is parallel to .the oamoan line, and the Maori lino when prolonged intersects it at the centre of. its greatest activity. Thero are thus two intersecting sets of tellurio cracks crossing the Pacific Ocean. . . -. It is likely that Ruapehu will be -active again—perhaps not in the .near future, but almost certainly after a long;space of time. Its general form,Me: character, of its' lavas, . though hot' in them•selves absolutely sufficient to warrant the prediction as certain, yet suggest, that Rua.V 'Vff Passed through all tho' phases of its life 7 history."„ - . Ngauruhoe and Its Orator. v" "Ngauruhoe is a cone of 7500 . feot in height,' ;WTote'Mr. Speight .for. a .Government'report last year, "which has been built up inside an crater formed on the south side of Tongariro. It is constructed of flows of augite-hypersthene-andesite: of a Clark colour, and of scoriaceous material of the same mineralogical composition. The lava-flows are very extensive,.,'especially on the western and southern side, where they cover largo areas'in th©:upper valleys of the rivers running -into 'tho Wanganui and in' iu Txr n y i ■%, Waibobonu, a tributary of the Waikato. They have flooded these valleys like, a viscid stream, spreading'out over" their floors, and wliera confined by thecraterring, hear Tama'-havo piled .up against it in thick masses, or ; have broken through where the ring has .been destroyed. Most of tho later flows are very dark in ookrar an'd resemble,basalts in appearance,• but''they are all '^augite-hypersthene-andesites.'-'■ On the sia©,. of: i ; tho -peak is in all 'pro l - 1 'babiuty the,,most recent lava-flow in' ''Now ll Zealand, which, report says; issued'from tho .grater, as. late ,as .1869,.^ an;extremely likely supposition considering'., its. fresh- appearance*100 'of!the flows'extend only, a'part, of the. way down. tEe;. steep cone», and this is covered over wido areas with vast quantities of loose scoriaceous material lyingrat .a very ;steep augle and set in motion at a ;toucn. The •crater of ' Ngauruhoe is an irregular .hollow, about 151 yards across; at the top of the mountain.' On the east, south; and- west, it has steep unscalable walls, over 100 feet high,. while on' the north side the wall has gone so-that it is'possible to enter the,floor of the orater. Two large apparently extinct mud volcanoes occupy the principal part of tlio floor of the crater, and only at ono point, ■is activity - shown, where from a fissure near , the western wall steam issues with roaring sound and explosive 'violence.. Also,, different parts of the crater-edge emit steam and give out' small .jpuffs of sulphur-laden vapour. The recent'activity of tho mud volcanoes is' evidenced by the great amount of mud which, covers, the upper slopes of -the, mountain,' and which,' according to Dr., Marshall, was ejected less than two years ago. This is, channelled as if it had been subjected to the action of streams of hot water, which was no-doiibt thrown out when the volcano was more active.- This crater has evidently reached the solfatara stage of activity. But rumblings and detonations from the inteijor of-the,mountain show that it has, still a store of energy left, which may make its presence known by showers of ashes and scdria, or even by streams of mol-.ten'-rock." '