Art. LIX.—Ruapehu and Ngauruhoe.
[Read before the Hawke's Bay Philosophical Institute, 10th August, 1891.]
In October, 1889, I had the honour of reading before this society a descriptive account of the geology of the country between Napier and Ruapehu Mountain by way of Kuripa-pango and Erehwon.* In this paper it is proposed to continue the description so as to include the volcanic district extending from Ruapehu in the south to Tapuaeharuru at the northern end of Lake Taupo. This portion of the volcanic belt of the North Island is even now seldom visited by tourists, and it was almost a terra incognita to scientific men up to the date of the Tarawera eruption in 1886. The destruction of the priceless Terraces and the disappearance of the Rotoma-hana hot lake drew the eyes of the scientific world of geologists to the spot which Hochstetter in 1859 had made classic ground by the brilliant yet simple description of his journey at a time when what is known as the Hot Lake District was little more than a name to Europeans. Hochstetter had travelled from Auckland to the Mokau River, and from thence had struck across country to Tokaanu, an important native settlement at the south end of Lake Taupo, and within a few miles of that portion of the volcanic region embraced by the mountains which go by the name of the Tongariro Range. He had ardently desired to visit the active volcano of Tongariro—or, more correctly, Ngauruhoe—just as Dieffenbach had wished to do when he visited the same spot eighteen years before. But Te Heuheu, a great and renowned Maori chief, ruled in those parts; and the native proverb around Taupo ran thus: “Ko Tongariro te maunga, ko Taupo te moana, ko Te Heuheu te tangata”—-that is to say, “Tongariro is the mountain, Taupo is the sea, Te Heuheu is the man.” The authority, or mana, of Te Heuheu extended from Tongariro over the whole of the Taupo district. Tapu had been set upon the Tongariro Mountain since the to-hungas had deposited there the bones of a former chief who lost his life at Te Rapa, near Tokaanu, in 1846; and woe to any one, be he European or other, who disobeyed the word of such a chief. Thus, then, it was that Hochstetter, though within four hours' walk of the northern slopes of Mount Tongariro, did not set foot on the mountain; nor was
[Footnote] *Trans. N.Z. Inst., vol. xxii., p. 422.
he able to see the crater-lakes, Pounamu and Rotoaira, that nestle between Pihanga, an extinct volcano overlooking To-kaanu, and Tongariro, and where once stood, so the Maori legend runs, the volcanic cone of Mount Egmont, now situated some eighty miles to the south-west. It must have been a great disappointment to Hochstetter, as it was to Dief-fenbach, to find himself so near to one of the most interesting volcanic spots in the Southern Hemisphere, and yet unable to traverse its slopes, where his great insight would have been of special scientific value in interpreting the geological history of so important a district.
In 1869 the mana of Te Heuheu over the district was in a measure broken, for colonial troops passed along the western side of the Tongariro Range when, in October of that year, the power of the rebel chief Te Kooti was shattered at Porere, a stronghold situated almost under the shadow of the active volcano Ngauruhoe. The district, however, was seldom or never visited until the year of the Tarawera eruption.
The earliest ascents of Ruapehu, as far as I can find, were made by Messrs. Maxwell and Beetham in 1879, followed by Mr. and Mrs. Birch, of Erehwon, in 1881, who crossed the mountain from north to south; but no account of either journey has hitherto been published. In the early part of 1886 Mr. Park, F.G.S., of the Geological Survey, and subsequently Mr. Cussen, of the Auckland Survey Department, reached what is known as the southern peak of Ruapehu; but neither appears to have attempted to cross the mountain, as was done by Mr. Birch's party, as the sequel will show. The accounts given by Messrs. Park and Cussen will be found in vol. xix. of the Transactions of the New Zealand Institute. In vol. xxi. of the same Transactions there is a paper by Professor Thomas on “The Geology of Tongariro and Taupo District,” in which an excellent description is given of the northern parts of the Tongariro Range, illustrated by some capital pictures and diagrams. Professor Thomas visited the Tongariro district at the beginning of 1888, but he does not appear to have ascended either Ngauruhoe or Ruapehu during his visit. As far as I am aware, the only available information with regard to the district under notice is to be gathered from the papers referred to here.
My own experience of the volcanic district extends over a period of twelve years, during which time the entire district from north to south has been visited by me, the southern portion three times, and the central or Taupo district many times. All the mountains or volcanic peaks belonging to the Tongariro series have been ascended and crossed, and the sources of the Whangaehu, Waikato, and Wanganui have been explored. The following remarks are based upon the knowledge
gathered during my various journeys to the district. The southern division of the volcanic zone extending from north Taupo, where the Waikato River leaves the lake, to Karioi, south of Ruapehu, is situated on a plateau varying in height from 1,700ft. to 4,500ft. above sea-level. The highest part of this plateau is between Ruapehu and the active volcano Ngauruhoe, which is the true watershed separating the sources of the Waikato and Wanganui Rivers. The plateau extends generally in a north-east and south-west direction for a distance of sixty miles, with a breadth varying from ten miles to thirty miles. Its eastern boundary is formed by the Kai-manawha and Tewhiti ranges of mountains, and on the west it has the old trachytic mountains known as the Hauhunga-roa Range, of which Hauhunga is the principal point. The latter range passes along the west side of Taupo Lake at a varying distance of from ten to fifteen miles. The plateau itself has a slope to the north-east and south-west, the height around Tapuaeharuru being about 1,700ft., and at Karioi 2,550ft., above sea-level. Almost in the centre of the plateau in its longest direction runs the present line of volcanic activity, which includes hot springs, fumaroles, solfataras, extinct and active volcanoes, and volcanic shafts or volcanoes in embryo. If a line could be drawn from the most southerly peak of Ruapehu, known as Paraetetaitonga, to Mount Tauhara, at the north end of Lake Taupo, it would include the following active and extinct cones: Ruapehu, Ngauruhoe, Tongariro (3), Pihanga, and Tauhara, besides numerous smaller ones. On the plateau to the west of Ruapehu there runs in a direction almost west by north a line of low volcanic cones, but craterless, for a distance of about two miles, the height of the cones being from 150ft. to 250ft. above the general level of the plain. Between the north end of Tongariro and Pihanga, and the latter mountain and Tauhara, are areas of depression, in the first of which is situated the beautiful Lake Rotoaira, and in the second Lake Taupo, the largest of New Zealand lakes. Rotoaira is 1,710ft. above sea-level, and Taupo is 1,250ft.
It would seem that at one period Taupo formed a much larger lake than it now does, and possibly it extended over and included Rotoaira, and much of the swamp-country between that lake and the streams which drain into the upper waters of the Wanganui. Rotoaira has an area of about 12,000 acres, and is about four miles and a half long by two miles broad. It is connected with Lake Taupo by a stream called Poutu, which passes over a trachytic lava-flow from Tongariro, and which has partly filled up the valley between the latter mountain and Pihanga. The distance between Rotoaira and Taupo is about fourteen miles, so that the fall is less than 40in. to the mile. In the Poutu Stream, at a place
called Karika, may be seen the legendary footprints of the great chief Ngatororairangi, who, when returning from the ascent of Ngauruhoe, crossed the stream at this spot. Whether Ngatororairangi crossed the river or not, the fact remains that there is what seems to be a human footprint in the rocks at the place named.
It is difficult to say whether Lake Taupo is simply an area of subsidence similar to what Rotomahana now is, or whether it is the remnant of what was once an immense volcano; but its whole surroundings seem to point to the latter surmise as being the correct one. It is surrounded by lavas and volcanic ejectamenta of almost every variety, and the craters of Pihanga, Kakaramea, Tauhara, and the fractured ones between Opepe and Tauranga-Taupo, with many others, are merely remnants of a volcano which exceeded even the dimensions of Ruapehu. Were the Tongariro volcanic range to subside, it would form a larger area of depression than even Lake Taupo, which covers an area of nearly 243 square miles, or 154,560 acres, as determined by Mr. Lawrence Cussen in a survey he made of the lake a few years ago.
The length of the volcanic range south of Tokaanu is about thirty miles, and the distance round the group, exclusive of Ruapehu, is sixty-five miles. The distance round Ruapehu cannot be less than forty miles. The portion of the plateau running along the eastern side of Ruapehu and Ngauruhoe is known as the Onetapu (sacred sands) or Rangipo (cloudy sky) desert, and it well deserves either name. Some parts of it are swamp and exceedingly dangerous, whilst the portion not swamp is made up of moving sands, scoria, cinders, clinkers, and tufas; and, although its traditional history is not reassuring, it is a spot well worth the attention of geologists, for some very curious and rare specimens of volcanic rocks are to be found in places left bare by the ever-moving sands.
On the plateau to the west of the mountains the conical hills of trachyte, to which attention has already been drawn, are objects worthy of attention. They are twenty-two in number, and extend in a north-west direction across the plateau for two miles or more, between the Tawhai and Whakapapanui Streams. In shape they are perfect cones, but there is no trace of a crater in any of them examined by me. They resemble large blisters on a lava-flow, and possibly they were formed by rapidly-moving lava passing over potholes filled with water, which, when heated, would tend to pass off as steam, thereby causing the lava to rise in the shape of a cone. I have observed that, when melted lead is poured into a mould which is wet or damp, blisters rise by the expansion of the steam, just in the way I imagine the volcanic cones were formed.
I shall now proceed to describe the three separate volcanoes of Tongariro, Ngauruhoe, and Ruapehu.
This mountain, when viewed from a distance, and especially from the saddle between Pihanga and Kakaramea volcanoes, over which passes the Maori track from Tokaanu, appears to have a gentle slope, and it seems as if one could ride to the top without difficulty. This, however, cannot be done; at least, it would be inadvisable to make the attempt. At the north end of the range is the solfatara known as Ketetahi. The date of the breaking-out of this solfatara is not known, although the natives residing in the vicinity of Rotoaira Lake are able to state that it has had periods of greater activity than now prevails. This curious and weird-like spot is situated at a height of 4,800ft. above sea-level, and is outside what properly belongs to the original cone of Tongariro. When approaching this spot the side of the mountain appears as if an immense slip had taken place in a clay-field; but a closer acquaintance shows that igneous forces have been and are still at work, the noises from the numerous steam-vents showing that intense activity prevails in this part of the mountain. Clays of various colours—red, white, and yellow—are found in abundance; whilst in many places sulphur, alum, pumiceous earth, and a somewhat brittle sinter are the prevailing surface-rocks. Some of the crater-basins contain a pitch-like material, which is thrown up in jets towards the centre, whilst in the walls surrounding these basins steam-vents occur, through which steam rushes with a tremendous force. Crystals of sulphur and alum are found in abundance near the vents, whilst large beds of almost pure sulphur are met with for several chains in the vicinity of the crater-basins.
The hot muddy waters flowing from this place are said to possess wonderful curative properties, and in the course of a few years no doubt this spot will be frequented by many persons of a rheumatic and gouty tendency.
About a mile further to the east, but still on the northern slope of the mountain, and at a height of 5,600ft., are situated the volcanic shafts known as Te Mari. The place is difficult to reach, but it presents special features both curious and suggestive to the student of vulcanology. There are three irregularly-shaped craters, surrounded by loose stones and débris, and in the centre of each crater is a circular shaft exactly like the shaft of a coal-mine, except that the diameter is perhaps a little greater. From these shafts steam containing a good deal of sulphuretted hydrogen is constantly rising, and deposits of sulphur are to be seen towards the margin of the shafts, as if a solfatara were forming. The shafts appear to be of great
depth, as boulders rolled into them could be heard rebounding, as it seemed, from rock to rock for some seconds. These curious craters are of recent origin, and were first called Puia Hou, or New Puia, when they broke out during the last eruption of Ngauruhoe, in 1868—69. They were subsequently named Te Mari, after the sister of Matuahu, chief of Otukau, situated a few miles to the north-west of the mountain, and whose death was supposed to have been hastened by the dreadful sounds that preceded, and the falling of stones, dust, sand, &c., that succeeded, the breaking-out of the New Puia.
At the time of the Tarawera eruption these craters sent out dense clouds of black smoke, but no eruption took place, although rumblings were heard for days before, both at Papa-roa and Poutu, situated near Lake Rotoaira. The craters forming Te Mari appear to me as being quite different in their mode of formation from the ordinary volcanic craters to be seen in other parts of the district. They certainly were not built up as ordinary cone-craters, such as are formed by the welling of lava from a vent, after the manner of an artesian flow, the plastic mass forming a cone round the vent; but they appear to have been formed by a gyrating process from below, and as soon as the gyrating force became sufficient to overcome the pressure of the overlying mass it gave way, and craters of irregular shape were formed. It appears to me that this gyrating force might even be approximately measured by simply estimating the mass of rock removed from the crater at the time of its formation. It may also be worthy of inquiry whether the opening of shafts of immense depth is the forerunner of volcanic action, or is simply a phase of decay similar to fumaroles and solfataras. The subject is one of much interest, and demands further consideration.
It will not be necessary for me to refer to the remaining part of Tongariro, as it has already been fully described by Professor Thomas in the volume of the Transactions to which reference has been made above. I would simply mention the fact that the Red Crater, which does not appear to have shown signs of activity at the date of the professor's visit, was steaming furiously in March, 1887, and in the same month in 1890; and I was told by Mr. Maunsell, a gentleman intimately acquainted with the mountain, that it was much more active a few years ago. No one visiting the district should miss the opportunity of seeing the craters known as the North Crater, South Crater, and Red Crater, in addition to Ketetahi and Te Mari, already described.
This, the most active of all the volcanoes of New Zealand, has a perfect cone-like shape, and is joined to the Tongariro
group of craters by a saddle composed of heavy basic lavas, along which one can travel from one mountain to the other in safety. At one period it would appear that Tongariro and Ngauruhoe were separated from one another; and, from the conformation of the country to the south and west of the mountain, Ngauruhoe has grown on the lava-plateau that once separated Tongariro from Ruapehu. Curiously, no lava-flow shows itself as if proceeding from Ngauruhoe either towards Ruapehu or Tongariro, and the only junction is by means of the saddle, which is an old lava-flow from the latter mountain. Ngauruhoe has been climbed by me on two separate occasions, the first time being on the 25th February, 1887, and again in March, 1890. Messrs. Owen and Peacock accompanied me on the first occasion, and Messrs. Russell, Caccia, and Studholme on the second. The ascent was made from the north-west by way of the Mangatepopo Stream, which is really the head-waters of the Wanganui River. On the second occasion our party not merely went round the crater, but as far as they dared into it, and the descent was made on the east, our camp at night being on the Waiohonu, a tributary of the Waikato.
The valley of the Manga-te-popo, when nearing Ngauruhoe, is a very interesting one. On the south side it is bounded by a high pig-backed ridge known as Pukekaikiore, a trachytic lava-flow, which is quite separated from Ngauruhoe by a deep V-shaped valley. This range was formed in the early history of Tongariro, and really belongs to that mountain, as all the lower slopes on the western side passing into the Waimanu Plain are made up of trachytic lavas, whilst there appear to be no such lavas in connection with Ngauruhoe. The north and north-west side of the valley is bounded by the old lavas from Tongariro, which are seen to pass underneath the lavas which now block up the valley. Near the west end of the valley there is an old crater known as Pukeorake, the northern half of which appears to have been blown out. This crater has a close resemblance to the one on Pihanga between Tongariro and Taupo South. The valley itself is filled with a lava-stream, or, rather, two distinct lava-streams, one of which is so fresh that it has the appearance of having recently cooled. The material is a heavy, black, shining lava, with a surface so rugged that travelling over it is extremely tedious, and even dangerous. There is no trace whatever of any vegetable growth. over the second or more recent flow, which does not extend more than 700 yards or so from the foot of the cone. This lava-flow, although so fresh in appearance, must have flowed from the mountain many years ago, as Bidwill, who ascended the mountain over fifty years since, refers, curiously, to this same lava-stream, and from this fact I am able to state
the direction he took in making his remarkable ascent in 1839 But reference will be made to this subject further on in the paper. Directly at the base of Ngauruhoe the Mangatepopo Stream takes its rise in a number of fine springs, some of which possess medicinal properties. The largest spring, however, is a soda-water one, with a flow large enough to supply the wants of Australia. I have kept a bottle of the water from this spring for four years, and it is still fit for drinking purposes.
The base of the cone on the Mangatepopo side is 5,560ft. above sea-level (bar., 25.2in.). Except in a single place, the foot of the ćone presents a steep face of lava to the valley, resembling a dark black wall with piliars. It is from here that the lava-stream passed into the valley, and traces of the same stream can be distinguished here and there up the side of the mountain till the crater is reached. Judging by the appearance of the wall referred to, the lava appears to have been exceedingly plastic, and of the consistency of treacle. The cone is very steep, being at least 40° on the north-west, and even more towards the south. The slopes are made up principally of ashes, cinders, and lava; but traces of sulphur are met with here and there. For 1,300ft. there is no trace whatever of vegetation, the last trace of a flowering-plant (Gentiana saxosa) being at a height of 6,100ft. In 1887 the ascent was made in two hours twenty-five minutes from the soda-water springs; but it took me twenty-five minutes longer in 1890, although three members of our party reached the summit in one hour fifty-five minutes, much to the inconvenience and danger of the others. In the first ascent our party kept together, and we rested six times—viz., at 5,900ft., bar. 24.9in.; 6,150ft., bar. 24.7in.; 6,550ft., bar. 24.3in.; 6,850ft., bar. 24.1in.; 7,200ft., bar. 23.7in.; and 7,500ft., bar. 23.5in. At the top the aneroid marked 7,655ft., and the barometer 23.4in. Thus the height of the cone by aneroid measurement is 2,095ft., with a barometric variation of 1.8in. Hochstetter, from a distance of twenty miles, estimated the height of the cone at 1,600ft., and its slope at from 30° to 35°; but he was not able to see any portion of the cone below the ridge which joins Tongariro and Ngauruhoe.
The top of the mountain I estimate to be not more than 150 yards across, being nearly circular, but very uneven as to height, and much shattered and broken between northeast and south. The crater itself consists of a primary or major one, within which are two minor or supplementary craters. The north-east and south-east walls of the major crater are much higher—perhaps 120ft.—than those towards the north-west and south-west. The lowest part of the crater-rim, which is the true lip of the crater, is towards the north-
by-west. Here the crater-lip has been broken away as seen in Plate XLV., and it is possible to walk for a distance of 50 yards or more into the major crater, along the eastern side. The walls of the major crater show banded rocks, as if stratified—old lava-flows—of various colours, for a depth of more than 200ft., and intense activity appears to be going on over the greater portion of the face exposed, as the steam and sulphur-fumes are seen to be issuing with much force. As already explained, the western half of the crater is much lower than the eastern half, and it is along the former side that two distinct and clearly-defined craters are formed within the major crater. Each crater is separate from the other, and the phenomena in each are different. The western rim of each of the minor craters is coterminous with that of the major crater, and, whilst the minor crater on the south-west may be said to belong to, and is possibly a remnant of, the old crater, the one on the north-west is as perfect in shape as the extinct crater to be seen on Mount Eden, in Auckland, and was, I should imagine, formed at a very recent date. Between the two minor craters, towards the west, there is a flat area on which an observer may stand and look into both craters. The diameter of the major crater I estimate at not more than 200 yards, and each of the minor ones at about 80 yards. As to their depth, I should think that 250ft. would be sufficient for the major crater, and from 100ft. to 130ft. for the minor ones; but this has reference to the craters only, and not to the shafts which are centres of activity in each. Neither of the minor craters can be entered, for not only is there great activity in the several holes in the floor of each, but the surrounding walls are steaming furiously. In the north-west crater I noticed that a great change had taken place during the interval between my first and my second visit. In 1887 the walls of the crater showed very little signs of sulphur; but last year, with the single exception of a beautiful vermilion band, there was nothing to be seen except sulphur (ferric chloride?) over the crater walls.
At present the south-western crater is the most active portion of the mountain, and dense volumes of steam and sulphurous fumes are constantly being given off. From the several shafts there is sound as from a thick rapidly-boiling substance; but the dense volumes of poisonous vapour which are constantly issuing make it impossible to penetrate the gloom; nor, indeed, is the observer anxious to make any close acquaintance with the seeming fiends whose noises and screechings continually arise as from those in the direst agony of despair. Extending from the lip of the crater on the north side for some distance down the slope of the mountain is a sulphur area—an immense solfatara which can be readily
distinguished from Tokaanu. And it would seem that the mountain is giving way in this direction: in some places a hard crust has formed over the sulphur; but the whole place is in a state of intense activity, and is very dangerous. Mr. Batley, of Moawhanga, Inland Patea, who is well acquainted with the mountains, has told me that on the east side of Ngauruhoe, about one-third of the way up, there is a vent which he has seen active on several occasions. “The vent,” he writes, “is rarely active, but I saw it busy enough a few weeks before the Tarawera eruption.” There was no trace of this vent in March last year, and I am inclined to think that the vapour which Mr. Batley has seen on several occasions comes from a decaying solfatara at the base of the saddle between Tongariro and Ngauruhoe, and which showed signs of activity in 1887. This solfatara to an observer on the southwest would appear as being on the east side of Ngauruhoe, at about the height named. Mr. Batley further says that the mountain was much higher in 1868, when he first saw it, the summit being sharp when viewed from the south-east. Horima, an intelligent Maori residing in the district, states that the top of the mountain fell at the time of the last eruption, which is said to have taken place in 1869; but it is certain that no lava was erupted at that date.
Although this mountain was held to be sacred, it was ascended so long back as 1839 by Mr. Bidwill, and in 1851 by Mr. Dyson. It is especially interesting to compare the accounts which have been kept of the ascents made by those gentlemen, as great changes must have taken place in the crater during the past fifty years. Mr. Bidwill's account is to me the more interesting for the reason that I have been able to tell from his description the exact spot he reached in the Mangatepopo Stream at the base of Ngauruhoe, and the track he took in his ascent of the mountain.
Bidwill's Account. Mountain ascended, 2nd and 3rd March, 1839.—“When I arose in the morning I was astonished to see the mountain around covered with snow except the cone, which was invisible. The natives said the mountain had been making a noise in the night, which at the time I thought was only fancy. As I was toiling over a steep hill I heard a noise which caused me to look up, and saw the mountain was in a state of eruption: a thick column of black smoke rose up for some distance, and then spread out like a mushroom. The noise, which was very loud, and not unlike that of a steam-engine, lasted for half an hour, and then ceased after two or three sudden interruptions…. I could see no fire, nor do I believe that the eruption was anything more than hot water and steam, although from the density of the latter it looked like very black smoke. I toiled on to the top
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of the hill, and was much disappointed at the other side of it: instead of being like what I had ascended, there was a precipice with a large stream of water at the bottom (Mangatepopo)….. As I progressed toward the cone I arrived at another stream of lava so fresh that …. it looked as if it had been ejected but yesterday…. I had no idea of the meaning of a sea of rocks until I crossed them: the edges of the stony billows were so sharp that it was difficult to cross them without cutting one's clothes into shreds…. I at last arrived at the cone. Ther., 65° in sun; bar., 25 14/20in. The cone is entirely composed of loose cinders…. After I had ascended about two-thirds of the way I got into what appeared a watercourse. It was lucky for me another eruption did not take place while I was in it, or I should have infallibly been boiled to death, as I afterwards found out it led to the lowest part of the crater, and, from indubitable proofs, that a stream of hot mud and water had been running there during the time I saw the smoke from the top. The crater was the most terrible abyss I ever looked into or imagined. The rocks overhung it on all sides, and it was not possible to see above 10 yards into it from the quantity of steam which it was constantly discharging. From the distance I measured along its edge I imagine it is at least a quarter of a mile in diameter, and is very deep. The stones I threw in which I could hear strike the bottom did not do so in less than seven or eight seconds; but the greater part I could not hear. It was impossible to get to the inside of the crater, as all the sides I saw were, if not quite precipitous, actually overhanging, so as to make it very disagreeable to look over them…. I did not stay at the top so long as I could have wished, because I heard a strange noise coming out of the crater, which I thought betokened another eruption.”
The following is Mr. Dyson's account as taken from Hochastetter, p. 372, et seq. (ascent made March, 1851): “The crater is nearly circular, … and I should think it was 600 yards in diameter. The lip of the crater was sharp. Outside there was almost nothing but loose cinders and ashes; inside the crater there were large overhanging rocks of a pale-yellow colour, evidently produced by the sublimation of sulphur. The lip of the crater is not of equal height all round —the south is the highest, and the north, where I stood, the lowest. There was no possible way of descending the crater. I stretched out my neck and looked down the fearful abyss which lay gaping before me; but my sight was obstructed by large clouds of steam or vapour, and I do not think I saw 30ft. down. I dropped into the crater several large stones, and it made me shudder to hear some of them rebounding from rock to rock.”
What makes these accounts more interesting and valuable is the fact that both Mr. Bidwill and Mr. Dyson were personally known to my respected and yalued friend the Rev. William Colenso, F.R.S.—who, I am pleased to say, is present with us to-night—at whose house, curiously, each traveller stayed on his return from the mountain. To me the circumstance is doubly interesting, because, when relating my own experiences to Mr. Colenso, I had no notion whatever that he had heard almost a similar story nearly fifty years before—indeed, years before I was born—and this from the very men who succeeded in what at that time was a dangerous and, indeed, perilous undertaking.
It will have been noticed that there are wide differences of opinion between the accounts given by Messrs. Bidwill, Dyson, and myself as to the diameter, depth, activity, &c.
At the time of Bidwill's visit the mountain appears to have been in the condition of a geyser, or puia, as the Maoris term an intermittent spring; nor does it appear that lava has been ejected from the mountains in any eruption since 1839, although flames are said to have been seen above the dense clouds of smoke which have always been present during times of increased activity.
That the crater was formerly much deeper than it now is appears certain; and it would seem that at the times of Messrs. Bidwill's and Dyson's visits the crater was not divided as it now is, but consisted of a single yawning abyss in a state of activity, resembling what was seen at Rotomahana shortly after the eruption of Tarawera in 1886. I can only account for the wide differences of opinion as to the diameter of the crater by supposing that the eastern walls were much higher and the rim much more unequal than at present. Hoch-stetter's drawing of the summit of Ngauruhoe, as seen by him in April, 1859, shows the western lip as being exceedingly low as compared with the eastern; and this, if it existed at the time of Dyson's visit, may have misled him as to the width of the crater during what was evidently a hurried and anxious visit. It is much to be regretted that no rough drawing was made of the crater by either Bidwill or Dyson; but it is evident that important changes have taken place within the past half-century. On the south and west, which are really the steepest and longest slopes of the cone, the mountain is deeply furrowed, and the peculiar arrangement of the lava bands with loose ashes and scoria interbedded is causing the mountain to wear away at a rapid rate wherever the lava-stream has broken away so as to expose the loose ashes immediately underneath. It is owing to this that the eastern slope, which at one time was covered with a reddish scoria-ceous band of lava about 4ft. in thickness, is now rapidly
breaking to pieces; and it is from this side that the ascent of the mountain would be easiest, were it possible to reach the place with the same degree of convenience as on the western side.
The rock-materials composing the mountain are greyish-red and jet-black lavas, containing large feldspar crystals, several of which I found of more than 1in. in diameter. There is no trace of pumice on the mountain, or in the valley of the Mangatepopo; but all the lower slopes to the east are covered with a kind of tufaceous material, overlaid with pumice grit and pebbles for a depth varying from a few inches to as many feet. With respect to the activity of Ngauruhoe, Mr. Maunsell, who is well acquainted with the mountains, informed me that the changes in the crater during the past twenty years have been numerous, that they are more marked after each winter, and that the activity of the mountain has been greater since the eruption at Tarawera. One curious feature with respect to the solidity of the mountain appears to me as being worthy of mention. One of our party at the time of my first visit, seeing a large boulder on the ledge between the two minor craters, thought to create some pleasure by rolling it down the side. The top of the mountain has a peculiar bulge, so that the first leap of the huge stone must have been 200ft. or more. The effect on the mountain, as likewise on each member of our party, was remarkable. The mountain shook as if it had been hollow, and each member on the instant voted against the rolling of boulders either down the mountain or into the crater.
At the base of Ngauruhoe, on the south-west, are two crater-lakes known as Nga-puna-a-Tama, or Tama's Wells. These lakes are situated on the highest part of the plateau between Ngauruhoe and Ruapehu, at a height of 4,560ft. They appear to have no outlet, and were seemingly formed in the same way as Echo Lake, Black Crater, and South Crater in connection with the Tarawera eruption, as loose boulders are to be seen scattered about in every direction. The water at the date of my visit barely filled the floor of the crater, in the centre of which could be seen the circular shaft, as in the Blue Crater lake on Tongariro. These lakes in the early summer are frequented by hundreds of mutton-birds (Puffinus griseus); but it is difficult to say on what they feed, as the water is fresh and apparently free from any kind of animal life. The birds breed in the vicinity of the lake, and the Maoris visit the spot for the purpose of taking the young when nearly full-fledged, being at that time extremely fat and good eating.
This mountain is separated from Ngauruhoe by a valley-plateau varying from a mile in the west to three miles towards the east in width. The highest portion of the plateau separates the sources of the Ohinepango and Whakapapanui Streams, tributaries respectively of the Waikato and Wanga-nui Rivers. The lakes just referred to are situated on the rise which really constitutes the watershed of the two rivers. There is no surface-connection whatever by means of lava-flows between the two mountains, the only junction being between Ruapehu and Tongariro by way of the Pukekaikiore trachytic range, to which reference has already been made. Ruapehu is the highest mountain in the North Island, and is an immense truncated cone, the base of which covers an area equal to Lake Taupo. It is situated a few miles to the north of the parallel of Napier. Although covered with perpetual snow for a depth of 1,200ft. or more, it is still active, and possesses a crater in the solfatara state, situated in the midst of the everlasting snowfields, and having ice-walls on two of its sides. The mountain consists of three principal peaks—namely, Paraetetaitonga on the south, Ruapehu on the west, and Te Heuheu, or Victoria, as it is sometimes called, on the north. The two former peaks each exceed 9,000ft. in height, whilst Te Heuheu is about 500ft. lower. These three peaks form the limits on the south-west and north respectively of what was once a single crater of more than a mile in diameter from north to south. From east to west the crater must have been greater; but the eastern wall is now broken away, and it is possible to go, as it were, into the heart of the mountain, to the base of the present crater, which appears to have been formed since the destruction of the original crater took place. I have visited this mountain on three separate occasions—first, from the north-west, in March, 1887; then, from the east, in January, 1888; and again, by way of the Kaimanawhas, in March, 1890. The mountain on the east and west is almost bare of vegetation, with the exception of a few low bushes along some of the guts which are evidently mountain-torrents in winter and early spring, when the snow begins to melt from the lower slopes. On the west and south a light bush reaches up the sides of the mountain to a height of between 5,000ft. and 6,000ft. The snow-line is lower on the west and south than on the other sides of the mountain, although towards the north-east there is a large snowfield of a trapezoid shape at a height of about 7,000ft.
I have already stated that a kind of rift has been made in the east side of the mountain, which carried away the east
portion of the original crater-lip. There the lava-flows are of immense extent, and the south wall of the old crater must be at least 1,000ft. in perpendicular height, appearing in its banded regularity as though the several lava-beds had been deposited by aqueous rather than by igneous agencies. Standing on the top of what once was the neck of a volcanic orifice, now full of black heavy laya, at a height of 7,400ft., in the midst of an amphitheatre of surpassing grandeur, one sees, as it were, the mighty results of heat and cold by contrasts. Towards the east there are miles of cinder-, ash-, and scoria-fields, with lava-flows of basalt, trachyte, and phono-lite; whilst to the north and west snowfields of vast extent rise to the summit of the mountain. It is here that the Whangaehu River takes its rise, in two distinct sources—one where the water is clear, but so impregnated with alum as to be un-drinkable; the other where the water is of a milky-yellow colour, and “so strongly charged with sulphates of iron and alumina as to taint the water from its source to the sea,” a distance of more than seventy miles. From what I have seen of this river I am satisfied that it has no connection whatever with the hot lake presently to be described. Like all streams fed by glaciers, the river is subject to sudden changes in both volume and colour; and its taste might be accounted for by the fact that its waters are forced to pass through rocks which are undergoing rapid decomposition by means of chemical and physical agencies. A long low spur on the left bank of the Whangaehu in its upper reaches separates the drainage of the Waikato from that of the Whangaehu. The two rivers rise within a few chains of one another; but the source of the former has already been described by Mr. Kerry Nicholls in his book on the King-country. It is possible to climb the mountain by way of the long low spur just referred to, but a spur running nearly north-east and south-west is perhaps the best track to take, as there is really no difficulty up to 6,400ft., where a party consisting of Messrs. Russell, Caccia, Studholme, Walker, Maunsell, and myself tethered our horses when making the ascent last year. From this height to Te Heuheu Peak the climbing is really hard, owing to the loose character of the material to be traversed.
By 10.30 a.m. we were on Te Heuheu Peak, in the midst of the snowfields, with a cloudless sky, and with a prospect glorious and inspiring. The whole of the Kaimanawhas, the Kaingaroa Plain, the Tuhua country and Waikato basin, and the whole of the volcanic belt as far as the Bay of Plenty, and even the ocean near Kidnappers and Te Mahia, could be distinguished in our panoramic view. Running from Te Heuheu Peak still to the south-west is a sharp line of rocks broken here and there, which forms the ridge of the mountain and
was the old margin of the crater-lip in its earlier history. From Te Heuheu there can also be traced, running to the south-east, another ridge, one portion of which I have named the Pinnacles, from its turret-like appearance. This ridge runs in the direction of that portion of the mountain already described as forming the sources of the Whangaehu and Wai-kato Rivers. About a quarter of a mile beyond Te Heuheu Peak the south-west ridge of black-lava rock suddenly disappears, and the snowfield, which has been separated up to this point, becomes one single field of great extent, traversed by hundreds of long crevasses of unknown depth. Curiously, all these crevasses appeared to have a general parallelism—that is, their general direction was south-by-west and north-by-east, showing that the slope or direction of movement in the ice was nearly east-and-west. It was interesting to observe how soon our party became accustomed to the crevasses, and actually in one place passed across several where a kind of ledge of broken ice had been left half-way across the gaping chasms.
Almost midway between the last ridge of rocks and the south peak of the mountain known as Paraetetaitonga, the crater-lake is situated. The icefield from the latter peak and Ruapehu slopes at a high angle towards the lake, and here the crevasses are very large, and the travelling is beset with some danger. Before reaching the lake our party was reminded of being in the vicinity of something different from ice by the unpleasant smells that came from the direction in which we were going. Presently the lake appeared in full view, and this within gun-shot of the spot where I had stood two years before, at the head-waters of the Whangaehu. A little careful travelling over steep sloping ice, traversed by crevasses, brought us—the first party that had ever been there—to the lip of the crater, and at once it became apparent that the lake was in a state of intense activity, exactly similar to what one sees at Wairakei in some of the mud-craters and geyser-springs there. Having learnt from Mr. Birch, of Erehwon, that it would not be possible to reach the lake, but that it might be possible to get to the lip of the crater, I took with me about 150 yards of thick twine and a tin bottle, with the intention of obtaining a specimen of the water, or mud, or whatever the lake should contain, for testing purposes; but all my efforts were unavailing, as the bottle got entangled by the jagged edges of the crater-wall, and eventually the string parted, much to my own disappointment. The length of the crater from east to west I estimate at about 450 yards, and its breadth from north to south about 375 yards; but, as the context will show, its size must vary at different periods of the year. On the south and west the crater-wall is composed of a solid mass of ice 250ft. or more in perpendicular height, and this wall forms the
terminal face of the glacial icefield extending from Ruapehu Peak to Paraetetaitonga. In one place only in this portion of the crater-wall was there a rock visible, and this was immediately in front of the last-named peak. The east and north portions of the crater-walls are composed of cinders, ash, and lava of varying colours, and banded with as much regularity as if the rocks were sedimentary deposits. The dip is east-north-east, at about 5°. The outside of this part of the crater has a steep cone-like slope, the base of which forms an almost perpendicular face towards the eastern side of the mountain already described, and it is still too warm for the snow to remain upon it. Steam was seen to be issuing from the red bands in the cinder-walls 100ft. or so above the surface of the lake, although the whole of the eastern half of the crater appears to be intensely hot. At the point of junction between the ash-beds and the ice on the south side is a waterfall; and the only sound to be heard as we sat on the rim of the crater, viewing a scene magnificently grand and awe-inspiring, was that produced by falling water, save that now and then a mass of ice gave way, and, with a fearsome crash, fell into the boiling lake. The colour of the water was soapy, or greyish-yellow, covered over in parts with a kind of scum, which now and again showed an iridescence similar to that of oil on the surface of water, and peculiar ripple-lines and scum-like bands could be seen spreading themselves over the entire surface of the lake. The water is in constant motion, the general direction of movement being apparently from west to east, the motion being not unlike that to be seen in a kettle of water when near boiling-point. There appear to be regular pulsations in the lake, and at intervals of from two to three minutes steam is suddenly given off, so that the surface of the water is hidden for a few seconds. After every pulsation, and explosion —no other word will explain the phenomenon—of steam, I noticed large cavern-like recesses below the ice-wall on the west side of the lake, as if the waters had subsided somewhat; but these slowly disappeared as the maximum of activity in the movement of the water approached, the hot water seeming to reach the ice-wall about the moment when the steam was thrown off the surface of the lake. I remained alone on the lip of the crater for more than an hour—the other members of the party having gone—Mr. Caccia to Paraetetaitonga, the others to Ruapehu—watching every movement of what appears to me as the most interesting and remarkable phenomenon in the whole range of the volcanic district. There can be but little doubt that this lake undergoes great changes, and it would seem that explosions somewhat like the one described by Bidwill as having taken place in Ngauruhoe take place from time to time on Ruapehu. “On the 1st May, 1889, the resi-
dents in the vicinity of Taupo Lake witnessed, about 11 o'clock, and again at noon, the spectacle of a grand and magnificent explosion of steam on Mount Ruapehu.” So runs a telegram from Tapuaeharuru of that date; and it appears that the Whangaehu was in high flood, and rose 3ft. or 4ft. in the short space of a few minutes. At the date of my visit there was ample evidence to show that a great geyser-like explosion had taken place, for quantities of blue mud and many large boulders were to be met with along the east and north-east portions of the snowfield in the vicinity of the lake, and a kind of wave-margin of coloured snow and blue mud could be traced on the ice between the south and west peaks, and which had evidently been deposited by an explosion of some kind. The wave-rim could be traced over the entire icefield sloping towards the lake, and the bluish-grey material upon it resembled what was thrown out at Rotomahana during the time of the Tara-wera eruption, and bore no likeness to any of the surface-rocks on the mountain.
In volume xix. of the Transactions there are two papers relating to Ruapehu. One of them is by Mr. Park, F.G.S.; the other by Mr. Cussen, of the District Survey Office, Auckland. Mr. Park ascended Ruapehu on the 8th January, 1886, from the south, and succeeded in reaching Paraetetaitonga, or the south peak. Mr. Cussen appears to have reached the same peak from the west on the 9th April of the same year. Each writer makes reference to the crater-lake, and it is exceedingly curious and interesting to find such a wide divergence between two most careful observers in their description of the crater, and who seemingly saw it from the same vantage-ground, and at an interval of only three months between them.
Mr. Park, in his account, says, “Immediately below us lay the great crater of Ruapehu. The crater proper, or what was probably the former vent, is situated not in the centre of the basin, but appears to be nearer to Paraetetaitonga than to the northern or western peaks. The vent, as far as could be judged from our high position, is probably 10 chains across. At this time it was occupied by a great sheet of ice of a bluish colour, and there was no appearance of steam or water.”
Of the same crater Mr. Cussen writes, “Deep down in a crateral hollow of basin-like shape, its steep sides covered with perpetual snow and ice, is a pool of water of a greyish-cream or drab colour…. From its peculiar surroundings of snow and ice it was difficult to estimate with any degree of accuracy the diameter of the lake…. It appeared to me to be of a nearly circular form, and 500ft. or more in diameter…. When I got to the top of the peak I noticed little clouds of steam rising from the surface of the
water. On watching more closely, the water appeared now and again to assume a rotatory movement, eddies and whirlpools passing through it from the centre to the sides, and steam flashing up from the eddies, leaving little doubt, to my mind. that the water was in a boiling state.”
It is difficult to harmonize the two accounts here given, so chameleon-like in character, as to the condition of the crater, except on the supposition that the glacier or icefield which surrounds the western half of the crater pushes itself forward as an immense sheet over the lake, covering it like a hollow dome, in the winter months, and that this ice-cap does not melt before February or the beginning of March. I do not see how it is possible to account for the crater being “occupied by a sheet of ice,” as Mr. Park states, in any other way, as from the manifestations of temperature on the walls towards the north and east it is certain that the activity of the mountain is not of recent date. When this lake was first seen, in March, 1881, by Mr. Birch and his party it presented phenomena almost identical with those seen last year, as the following account, supplied by Mr. Arthur Russell, a member of the party, will show. He writes, “We made straight round the east slope of the west point (Ruapehu), having now the crater in full view. It was about 400ft. perpendicular below us, the snow sloping easily to it for 400 or 500 yards, and then falling sheer down some 200ft. into the crater…. The lake is nearly round, with its greatest diameter south-east and north-west some 700 yards by 600 yards. The surface of the lake, which is of the colour of very dirty soapsuds, was covered with steam-wreaths, which made it difficult to say whether the water was in motion or simmering…. Small clouds of steam rose and passed off at intervals.”
Here, then, we have proof that the crater of Ruapehu presented the same appearance when seen ten years ago as what it did in March last year, when seen under much more favourable conditions; so that the difficulty of accounting for the state of the crater as described by Mr. Park becomes still more perplexing. But I think it is possible to go yet further back for evidence to prove that the crater is by no means of recent origin. This evidence is to be found in a peculiar kind of heavy siliceous pumice on Ruapehu itself. I well remember that in 1888, when Messrs. Petrie and Hamilton were with me in the exploration of the Whangaehu River, on our approaching the mountain we were led to believe the eastern slopes between 5,500ft. and 7,000ft. were well grassed but somewhat browned, owing, as we supposed, to the long period of dry weather experienced in the district. A special journey was made to the supposed grassy slopes in anticipation of some rare botanical specimens, and the disappointment of my
friends, who are ardent botanists, can be well imagined on finding that they were nothing more than a dull-brown heavy pumice—a trachyte pumice— partly rounded and partly angular, and varying in size from an apple to a cocoanut. This pebbly pumice covers certain of the slopes below the snow-line to the north-east and south-east of the crater, and it has the appearance of having been ejected at a very recent date. It is certainly distinct from the other varieties of rock on Ruapehu, and either it must be the frothy remnant of very recent lava-flows, or it must have been deposited by explosions from Ngauruhoe, Nga-puna-a-Tama, or the crater on Ruapehu itself. My own opinion is that activity on Ruapehu has been continuous, similar to that on Ngauruhoe and Tongariro, and that each mountain is in the condition of a solfatara.
We have seen that Ngauruhoe, fifty years ago, according to Mr. Bidwill, was in a geyser, or puia, condition, and ejected mud and hot water at intervals; whilst in 1869–70 the same mountain, and also Te Mari, threw out vast quantities of fine dust, pumice, and ashes. Less is known of the hoary Ruapehu. It is a spot dreaded by the Maoris, and its history dates back scarcely a dozen years; but during this brief acquaintance with the mountain there has been sufficient evidence to show that the crater is by no means dormant. The deposit of pumice on its eastern slopes, the present heated state of the crater-walls, and the cone-like slope of the crater towards the east and north, all go to support the view that the activity of the present crater is of long duration. Indeed, had it been otherwise the ash- and cinder-bands and the crater itself must have broken away long since by reason of the rapidity with which the work of rock-disintegration proceeds in the upper regions of the atmosphere, more especially within the limits of the zone of perpetual snow.
The rocks composing Ruapehu are principally made up of basic and what Judd terms “intermediate” lavas, the only trace of truly acidic rocks on the mountains being the pumice trachyte, which is found on certain slopes in the vicinity of the crater. By way of the Whangaehu River heavy black lavas predominate; but there is a range made up principally of phonolite, or clinkstone, which Mr. Park also describes as being found on the south side of the mountain. Slabs of this rcck were seen more than 10ft. across, very smooth and thin, almost like slate, but with a metallic or bell-like ring when struck. At the junction of the two head-streams of the river there is a large waterfall, and here the principal rock is a pitchstone. Along the north-east slopes there are heavy
basalts and rust-red lavas. Pieces of tachylite were also found scattered over the slopes, but no large rock-masses of this were seen by me in any of the places visited. The highest point of the mountain on the west is made up of heavy black lavas, but lower down the lavas are of a dull-red colour, and they present the appearance underneath Te Heuheu Peak of having but recently cooled.
The curious thing about Ruapehu is the distribution of acidic rocks over basic ones. Professor Thomas points out, in his “Notes on the Volcanic Rocks of the Taupo District,”* that “The order of succession of the rocks at any given vent or in a given volcanic district is such that the more basic follow the acidic lavas.” As basic rocks are mainly found on Ruapehu, it may be assumed that the volcano is in its final or later stage of progress. There is plenty of pumice everywhere surrounding the mountain—in fact, the whole plateau appears to be composed of pumice and tufas. But by what process a pumice-trachyte came to be scattered atop of heavy lavas I make no pretension to explain. It may be that the crater-lake is the beginning of a new period of activity in the history of Ruapehu; but this would be contrary to the prevailing theory as to the sequence of flows from a volcano during its periods of activity. After all, the world knows comparatively little as to the changes which volcanoes undergo from time to time, and the periods of activity and their causes are still unknown or are imperfectly understood. By obser-vation and the collection of facts it may be possible to generalise with regard to volcanic phenomena; but facts must be the basis of all generalisation, and it seems that the facts regarding the products of Ruapehu point to the possibility of acidic rocks succeeding as well as preceding basic ones in the history of a volcano.
Traditions concerning The Mountains.
When at Tokaanu three years ago I endeavoured to obtain all the information available, traditional or otherwise, bearing upon the mountains. Of Ruapehu there is a legend that it is haunted by a spirit called Te Ririo, who entices men from their homes and causes them to wander hither and thither over the mountains until they become insane, when he leads them into one of the mountain caves to die, or until rescued by their relations. This is very meagre concerning such an important mountain; but it rather shows what a dread the natives had of the Rangipo desert and its trackless and ever-moving sands, towards which many of their people passed never to return. As far as I can learn, these Maoris possess
[Footnote] * Trans. N.Z. Inst., vol. xx., p. 307.
no knowledge whatever of there having been an eruption on Ruapehu; but this may arise from the dread among them as to the dangers to be met with in the vicinity of the mountain, and to the absolute sterility of the country thereabouts.
I have already made brief reference to the supposed location of Mount Egmont (Taranaki) on the spot where Roto-aira Lake now stands; and of Tongariro and Ngauruhoe it is said that eruptions always occur at the death, or coming death, of their great chiefs.
The origin of the volcanoes and of all the volcanic phenomena is accounted for by reason of the fact that Ngatoroai-rangi, the chief priest, or tohunga, who piloted the Arawa canoe from Hawaiki, having, in company with Tia, another great chief, taken possession of the country extending from the Bay of Plenty to Ruapehu for his people, ascended Nga-uruhoe (which at that time was not a volcano) to perform the needful incantations, and, in accordance with Maori religion, to set up a tuahu, or altar, so as to insure to his people safe possession of the country and a happy and fruitful future. When in the midst of his karakias, or incantations, the cold became intense, and it seemed as if he must die. It then occurred to him to send for the sacred fire, which was kept during his absence in the custody of his sisters Hoata and Pupu. Seeing them at that moment on Whakaari, or White Island (120 miles distant), he urged them to bring the fire if they would save him from perishing. In response, one of his sisters, leaving a portion of the sacred fire on Whakaari, at once dived into the sea in the direction of Tongariro, and reached her starving brother in time to save him from a cruel death. In her passage underground she set fire to the world below, but here and there she came to the surface to breathe; hence all the hot springs and puias between Whakaari and Ngauruhoe. In commemoration of the event Ngatoroairangi left the sacred fire burning in the mountain, and also ordered that it was not to be extinguished in Whakaari; hence these two active craters and all the volcanic phenomena in the North Island.
But, however meagre and unsatisfactory Maori tradition may be with respect to volcanic agencies, the evidence of a long-continued period is to be found not merely within the great plateau immediately surrounding the mountains, the outcome of volcanic eruptions, but the evidence of long continuity is to be met with over all that portion of the North Island where it has been my privilege to travel. In our own town (Napier) the very soil of our gardens is made up in great measure of volcanic products, and the Kidnappers was separated from Napier and Redcliffe, near Taradale, by reason of the immense beds of pumice and other ejectamenta that
once filled the entire area now partly covered by ocean and partly by rich fertile plains. But the distribution of volcanic rocks and the evidence as to the age of the volcano under notice must be left for another paper. So also must an account of the flora to be met with on and around the mountains.
Explanation Of Plates XLIII.-XLIX.
XLIII.—Map of country round Tongariro.
XLIV.—Map of summit of Ruapehu.
XLV.—Crater of Ngauruhoe in March, 1890, from the west.
XLVI.—Crater-lake on Ruapehu from the north-east.
XLVII.—Sketch-map of Tokaanu, showing location of hot springs.
XLVIII.—Ngauruhoe from Tongariro.
XLIX.—Tongariro from summit of Ngauruhoe.