GEOLOGY OF NEW ZEALAND.

New Zealand Herald, Volume I, Issue 232, 10 August 1864, Page 4

GEOLOGY OF NEW ZEALAND.

KOTO-MAI!ANA (oil THK WAItM LAKE) AND ITS HOT SI'IUNGS. The Lulcc District, so called on account of its numerous takes, is situated about two days journey i'lom the Uav of lMunty. It is aliuost exclusively inhabited by the natives, who have selected the beautiful and fertile bunks of Tiorotorua and Tarawera as their settlements. The Mission Station at Tcmu (the Rev. Mr. Spencer's residence) is at present the only European habitation, and is the resort of many travellers ami naturalists, who visit the neighbourhood dnring the summer months. The principal point of attraction of this region is l?oto-nial)ana, or the Hot Lake, with its wonders, a visit to which well repays the fatigues of a lew days' travelling through New Zealand rush and swamps.* It is not one of the smallest lakes of the district, .scarcely exceeding in length three-quarters of a mile from north to south, and in width a quarter of a mile. I hardly believe that this small, dull-green lake, with its swampv borders, and the surrounding barren and miserable-looking hills, which are destitute of trees, and onlv covered with fern, would come up to the expectation of the traveller, who lias heard so much of its wonders. That which makes it the most remarkable of all the lakes ot New Zealand, nay even the most remarkable, of all spots of tlio earth, lies mostly hidden from the view of the new arrival —except "the immense clouds of steam which arise everywhere—which leads to the supposition that in reality nothing is to bo seen. The name of " AVarm Lake" (Koto —lake; mahana —warm) may in the full sense of the work be given to it. The masses of boiling hot water which spring up along the banks and from the bottom of tho lake, are really collossal. Of course the whole lake is warmed by them, but the temperature of the water dilfers considerably in various places, as they are nearer or further from the springs. At many points, even in the centre of the lake, the thermometer rises from 30° to 40 ° 0., (S6 ° to 101° F.) while near its stream I found it only 20 °c. (7S'S ° F.) The water is thick and swampy, and neither tish nor shellfish can live in it. Otherwise the lake is a favourite resort of innumerable acquatic birds, who build their nests on its warm banks, while they find their food in tho waters and swamps of the cold lake Rotomakariri. The natives shoot them at certain seasons but at other times they do not permit either European or themselves tho pleasure of sport. The birds of Roto-mahana are at this period strictly " tapu." Visitors who intend to stay for a few days at tho lake are recommended by the natives to select as their quarters tho small island Puai. This is a rock, ■1 '1 feet high, 200 feet long, and nearly 100 feet wide, small huts aro there erected, - in which we made ourselves as comfortable as possible. Hut, I believe that any ono who did not know that persons have lived hero for several weeks, would only with great difliculty be persuaded to remain here even for one night. The continual roaring, rushing, singing, buzzing, boiling sound, and the intense heat of tho ground, impresses a feeling of terror, and dming the tirst night of my stay I awoke suddenly, an the ground under me became so hot that I could not possibly bear it. In examining the temperature, I made a hole in the soft ground, and placed the thermometer in it. It rose immediately to boiling-point, and when I * Tile journey from Auckland is generally made in from one to two days by seit to Tauranga with a favourable wind, l'rom Tauranga one can arrive in two days at Tarawera and Roto-mahana Lake, either direct or by Maketu —both roads eciualiy bad. The return can be made over the l'atetere plateau to the "VVuikato Itivcr, and from this by canoe to wlioncc tho Groat South lload loads to ,A.uckland.

t.nnk it out, a stream of hot steam inst-anty ascended ". ■so that X hastened to cover it again a=> fast as X could. Indeed, the whole island is nothing but a torn and fraetarod ro"l<-, decomposed and softened by steam and gase-i. which, almost h.>ilH in softness, may at anv moment tumble to pieces, and vanish m tile liot water of the inlie. Hot water bubbles lip everywhere. either below the surface of the lake or above it; ami wherever a hoio is nlatle in the gi'oiind, or the mist. removed which is formed over the fissures of the vock, hot steam bursts forth, which we used for cooking our potatoes and meat, spreading them on ferns according to native custom. The centre of attraction and of interest is the eastern bank, where are tho most important of the springs, which indiied the lake has to thank for its renown, and which are tho most magnificent and grand of all hot springs at present known. To Tarata. is situated at the north-eastern end of the lake. It lies 80 feet above the level of the lake, within a crater which is open towards the side of the lake, and forms the principal basis of this mighty bubbling spring. It.is SO feet ions? by 60 feet broad, and filled up. to the brim with .clear boiling, water, which issues in the centre several feet higher, looking beautifully blue in its snow-white .incrustod basin. Enormous clouds of. steam,, rising. tipw;iirds; ai-e reflected in the blue mirror of the basin. The temperature of the water, which probably reaches to boilingpoint in the centre, was 8-1 ° c. (183-2 c F.) near the rim of the basin. The water is neither alkaline nor acid ; it. has a slightly salt taste, and possesses in a high degree the property of petrifaction, or rather of incrustnition. The sediment consists, as in the hot springs of Iceland, of sllicß, and tho overflow has formed on the slope of tho hill a system of crystal terraces, which, appearing almost as white as marble, prcsert a sight which it is impossible to describe. It is as if a cascade, rushing over stops, had been suddenly arrested, and transformed into stone. Each of these steps has a small elevated rim, from which hang delicate stalactites; and here and there; an the smaller and broader steps; formed water basins. These til'.ie basins, filled •with, crystal water, form natural baths, which could not bo surpassed by those constructed bv the most refined luxury. One can select his bathing^plnce.either deep or shallop-; small or large, and ; of every temperature according to ljis taste, as the basins situated on Ihe hteights near the sourco contain warmer water than those of the lower steps. Some of the basins are so large that a person can swim in them with comfort. Such is n description of tho celebrated Te Tarata spring. The natives assert that tho whole water in the principal basin is sometimes ejected suddenly with vast force, and that it is possible to look into the empty basin, thirty feet

deep, which fills again speedily. A path leads from the foot of the Te Tarata spring through the bush to the great Ngahapu.spring- The basin of this spring is 40 feet long and 30 feet broad. The water within it is in constant «nd dreadful agitation. It is only for a few moments that the water is quiet in the cauldron, when it again bubbles up, and is thrown eight or ten feet high ; and a foaming surf of boiling hot waves steam over the walls of the basin; so that the observer is obliged timidly to retoreat. The thermometer rises in these springs to 98° c.(208'4° F.) Further south, close :to tho banks, is situated thq Te TakapO spring—a boiling water basin of 10 feet in diameter, the geyser eruption of which rises to a height of 30 to 40 feet. Not far from this spring the traveller arises at a hollow called Waikanapanapa (Variable Water), the approach to which is covered with bush, and somewhat difficult, as one has to pass several suspiciouslooking places, where there is danger cf sinking in the boiling mud. The cavity itself appears like the crater of a volcano ; tho walls, bare of vegetation, are rent and toln ; {jieCes and tongiies of rock of white, red, and .blue fumarolic (lay rising upwards like spectres; threaten to fall every moment. The bottom is fbrthed of fine mud, and silicious stalactites, broken into every form and variety, lie about like pieces of ice after the breaking up of a frozen stream, nero is a deep pool filled with bubblingmud—there a cauldron full of boiling water-—near it a dreadful hole which, with a hissing noise, ejects a column of steam ; and further on small mud hills (fumaroles), from two to five feet in height—iniid voleanos, if the nanio may be applied to them—which, with a dull noise, throw out of their enters boiling mud, and represent, on a small scale, the effects of largo valcanos. In tho back-ground is situated a green lake named Roto-punamu, an extinct spring. Coming out of the north side of the cave is seen lying picturesquely amongst rocks and bush the spring Rua Kiwi (Kiwi Hole). It is an oblong basin of sixteen feet in length, filled with clear simmering water. The banks of the lake assume here a steep and rocky character; hot springs bubble out of them • below the surface of the water, while on the slope are situated, near the Ngawhana spring, the vacated huts of a Maori settlement of the same name, and not far oft' is the intermittent spring Koingo (the Sighing), the emission of water from which only takes place from three to four times a day, and alternates with the neighbouring Whatapaho. The above-mentioned springs arc the principal ones ; on the slope of a hill, rising about 200 feet ' above the level of the lake, there are more than 100 places that eject steam. South of this steaming hill the banks are lower; on the south-east side of the lake is situated the spring Khakaehu, with which are connected a whole chain of boiling springs, ejecting party clear and partly muddy vater from the swampy ground. In the flats are several small cold-water lakes, and in the back-ground rises a mountain —Te Rangi Pakaru (Broken Heavens) —on the west side of which, from a crater-like hole, there stesms a mighty solfatara producing much sulphur. Un the western bank, the yreat terrace spring— Otuka Puarangi (Cloudy Atmosphere), forms the counterpart of Te Tarata spring. The stalactic steps ! reach to the lake, and one ascends as on artificially formed marble steps, which are decorated on both sides with green shrubs. These terraces are not so grand as those of Te Tarata, but are more delicate and of a beautiful pink hue, which adds a peculiar charm to this wonderful formation. The basin of . this spring is 40 to oO feet in diameter, and appears as a calm, blue, glimmering, steaming, but net-boiling mirror of water. On the northern side, at the loot of the terraces, is the solfatara Whaka-taratara —a [ sulphur pool in the true sense of the word, from which a hot muddy stream runs into the lake. 'There aro about twenty-five large hot springs—or lif/mr/iiis, as the natives call tin m—at Roto-mahana. 1 dale not venture to estimate the number of the .-mailer ones. And Roto-mahana is only one point of a rent above 100 miles long, and 1" wide, between ' the active crater of Tongariro and that of the White . Island in the Bay of Plenty, throughout which hot ( water and steam are ejected from the earth at innu- , merahlc points. These grand thermal springs have proved most cfiicient in curing diseases of tho skin aud rheumatism, so far as the experience of the natives goes ; and [ it is not improbable that in a few years Roto-mahana , will be one of the most frequented bathing-places for | Australian and Indian invalids. The map is the first that has been compiled of the lakes and springs, and may servo as a guide to tho tourist in this inteL resting district. Professor Dr. v. Feliling, of Stuttgart, has had the kindness to analyse the waters of the lake aud the stalactites. On account of the small quantity of the water, a quantitative analysis could not be made. A.—Aimfysis of the Water. 1. Te Tarata Spring, by Mr. Melchior. 2. Rua Kiwi Spring, by Mr. Melchior. 3. Roto Punamu, by Dr. Kielmaier. In 1000 parts of water was contained : 1. 2. 3. Siliceous acid ... 0,164 0,16S 0,231 Chlornatriuua ... 2,504 1,992 1,192 Residue 2,732 2,462 1,726 B. —Silicious Stalactite of JJfj>osit of the different Sot Springs on the banks of the lioto-mahana. 1. Deposit of Te Tarata Spring : fa.) soft, (b.J hard. , 2. " of the Ngahapu Fountain, j 3. " of the Whatapolio Fountain, '4. " of the Otuka Puarangi Spring, The analysis executed by Mr. Slayer gives: I. ' •->. 3. -1. u a. b. j" Silicia 6«,03 8-1,78 79,31 88,02 80, SO t Water and organic) substance . . ) 11,52 12,SG 1t,50 '>''■ 11,61 , Oxide of Iron )_ ,- n joy 2,99]-Traces Argillaceous earth J ' , o,b/ J J » Clialk . . . 0,15") 0,27 0,3b ! Magnesia . . . 1,09 0,251 Traces 5 Alkalies . . . 0,38) o,±~ J 0,10)