THE ERUPTION AT TARAWERA.

Auckland Star, Volume XVII, Issue 214, 11 September 1886, Page 6

THE ERUPTION AT TARAWERA.

ASCENT OF THE MOUNTAIN.

A New Lnltd r'ormod at Its Base.

Mr S. Percy Smith, Assistant SurveyorGeneral, has returned to Auckland, after making a complete examination of Mount Tarawera and its surroundings. To Mr Smith belongs the distinction of being tho first explorer who ascended the volcano subsequent to the eruption, and his inspection has led to a number of very interesting discoveries, which throw much light upon the character of the great convulsion. It has been ascertained that, below the vast chasm on tho south end of Mount Tarawera, which was seen in the first observations, and continuing from its terminus near Wio bottom of tho mountain to within half -a - mile of Lake Rotomahana, there ia a huge fissure, three quarters of a mile long by an eiehth of a mile in width —its banks 150 to 200 feet high, the upper fifty feet being of ground built up with ejected matter. This tremondous earth-rent has become filled in with water, the drainage of the mountain, and now forms

A Now Lake. absorbing and extending the little lake Botomakariri,: the name which Mr Smith has applied'to ita more expansive successor. The water is at present of a dirty muddy colour. The site of the new lake, prior to the eruption, was an easy-eloping valley, in which lay the original Rototnakariri, a little* lake not more than an eighth of a mile tn diameter Between the new lake and the great chasm in the end of Tarawera, a small green lake intervenes, divided from the considerable sheet of water below it by a narrow, knife-like ridge, which is too sharp to walk across. The green lake is simply a crater of about 75 yards in diameter, containing a considerable quantity of wator. Immediately beyond, and above it, commences tho great chaem at tho end of Mount Tarawera, still coloured round its margin with forro-chlorides, which, seen at the distance, tavo rise to tho early report that the ssure was bordered with deposits of sulphur. This vast chasm starts about 250 feet above the level of Lake Tarawera, and extends to the top of the mountain, forming a deep gorge, averaging about 200 yard* in width ; its walls at tbe bottom are 250 feet high and are composed of black and red scoria. The floor, which follows the upward slope of the mountain, is also of scoria; steam and occasionally a deep brown smoke issue from crevices in the side and bottom. As the adventurous explorer penetrates this gigantic chasm, hewn in a single night by the Vulcanian powers, its walls increase in height until they attain an altitude of about 800 feet above the floor.

The Mountain Rent from End t« End.

A strip of nbout a quarter of a mile separates the great rift in tbo south end of Tarawera from the deep fissure which has torn open the top of Tarawera and Ruawahia from one end to tha other, a distance of about a mile end a half. This fissure, having an average width of about 220 yards, is divided by three sharp ridges into four sections, or craters, tho central one about 600 feet deep. The sides and bottom are composed of scoria, from which stotrm and suffocating gasses, the odour of muriatic acid being the most prominent, issue. At the gap that separated Kuawahm from Wahanga, there is a narrow ridge, and then the fissure continues the fulflength of Wahanga, being divided into three craters by sharp ridge?, the one nbout 1,400 feet deep from the summit of lluawahia. The whole of this great gorge, except where the original formation of the mountain cropsout, is covered with scoria—some of it in largo blocks, but mostly fine, having the general appearance of the n:oria forming the cone cf Mount Eden.

Was Thcro Any Lava?

There is no trace of a lava flow on the mountain, although probably a bed of molten rock lies boneath the acoria deposit, which has raised the height of Kuawahia about 170 feet, and altered its outlino very conaiderably. There is, however, abundant proof that the convulsion has not been a mere displacement of the original constituents of the mountain, bat that the rock was ejected in an incandescent condition. This is not merely established by the existence of the deep beds of scoria, but by the perfect bomba that are found upon the tops and sides of the mountain. The marked difference in the character of the unchanged rocks of the old mountain and the mass of ejected matter super - imposed upon it also places the question beyoad conjecture. The great fissure follows the general south-west direction which wus noted in its extension through Rotomahana towards Okaro. The examination of Tarawera serves to heighten rather than to Ics3en die first reports of the gigantic character of the eruption. It will be observed that the volcanic explosions have not simply opened two or three small craters, but havo forcibly expolled the whole centre of the massive three-peaked mountain or range for a length of about two and a-half milo?, to a depth varying from 400 feet to 1,400 feet. Beyond this is the enormous gorge 600 feet wide, and from 250 to 800 feot deep blown out of the side of Tarawera ; then the oxcavation .of the mass of earth and rock to form the bed of a lake three-quarters of a mile long by an eighth wide.

Rotomahana and tho Southern Craters,

Mr Percy Smith made a careful examination of the condition of Rotomabana and the southern craters. The bed of Rotomatiana is now about 250 feet below tho old Lake level, and is considerably lower than the level of Lake Tarawera, into which its surplus waters formerly flowed down the Kaiwaka Creek. Fortunately, a considerable breadth of made ground prevents any inflow from the great lake upon the Rotomahana crater.or there would be a very lively contest between the cold stream and the subterranean fires that have expelled the old waters of Rotomahana, and are still steaming and fumiDg from a hundred mouths. With the exception of an area of about 250 yds by 100 yard?, still covered with water, Rotomahana is now entirely composed of steam holes, or craters, some of them 50 yards across. These are fumiDg away amid a desolation of sand and mud in data and hillocks, the highest of tkeee heaps of made ground being towards the northern end of the Lake, near tho old sita of tho White Terrace. On this hill, which is about 400 feet high, Mr Smith found the flag planted

by the Stab exploring expedition, and named it the Star Hill. A moro careful survey proves that tho guesses that wore hazarded with respect to the height of tho Black Crater considerably overßhot tho mark. Its external height is nbout 400 feet, not much more than 20 feot of it formed by the ejected matter. Tho depth of the crater is about 320 feot, and it is now fillod with water, which continues to give oft'heavy clouds of steam. An eighth of a mile from this crater, Mr Smith found a block of stone at least 100 tons in weight, which had evidently beon projected from the crater, showing tho gigantic forco put forth during the eruption. One of tho inoßfc energetic stone-spitters in this locality is situated between the Black Crater and Okaro. Some ten acres ef ground around this focus afford a very interesting field of investigation for tho goologist. It baa net built up a cone, and the hole mado by the eruption having become rilled with water, a perfect example is furnished of the formation of the crater lakes with which wo are so familiar. Owing to a singular echo which is produced in the vicinity of this Lake, it has been named the Echo Lake Crater. Lying botween this and the Black Crater, a smaller rent is still actively steaming. The other features of tho adjacent country have not undergone any material change sinco they woro last described, excepting that a now crater, situated on the site of what iB known as the Black Terrace, has broken out, and is now throwing out considerable auantities of sand, mud, and stones. This place 13 about half a mile west of Rotomahana.