Art. XXXVI.—On the Murchison Glacier.
[Read before the Philosophical Institute of Canterbury 4th September, 1890.]
Introductory.—Some Remarks on the Principal New Zealand Glaciers.
It is a strange fact that the average New-Zealand knows but little of the physical features of his own country. It is strange that he knows still less of its great mountains and glaciers, and of all the marvels of nature which immediately surround them; but it is stranger yet that there should lie hidden for so many years a glacier of such extent and importance as the Murchison, whose ice was trodden for the first time in the summer of last year. It is also interesting to note that almost all scientific explorations and records concerning our essentially alpine mountains have been made by foreigners or visitors to our shores.
The principal New Zealand glaciers on the eastern side of the main range are situated in the very heart of the Southern Alps, and comprise those at the head-waters of the Rangitata River—namely, the Havelock, Clyde, and Lawrence Glaciers;
those at the head-waters of the Godley River—the Godley and Classen Glaciers; and those at the head-waters of the Tasman River—the Mueller, Hooker, Tasman, and Murchison.
Amongst the names of men who have first explored these glaciers, that of von Haast naturally occurs to us, and the records he has left of his work will always be regarded as a valuable tribute to science and a lasting memoir of his indomitable energy and perseverance in opening up the orology of our magnificent chain.
The Rangitata glaciers were first visited in 1860 by the Hon. J. B. A. Acland and Messrs. C. G. Tripp and Charles Harper; and in 1861 von Haast made his first journey to the same quarter.
In 1862 von Haast explored the head-waters of the Godley and Tasman Rivers, traversing parts of the Godley, Classen, Hooker, Mueller, and Tasman Glaciers, and observed from the last-named the Murchison Glacier, which lies in the great valley on the eastern side of the Tasman, enclosed by the Malte Brun and Liebig Ranges.
Some few years later, however, these glaciers were more thoroughly explored by Mr. E. P. Sealy, of Timaru, who in one instance—viz, that of the Godley Glacier—crossed the saddle at its head, which leads to the West Coast.
In still more recent years the more important observations of note are those of the Rev. W. S. Green in 1882, of Dr. von Lendenfeld in 1883 on the great Tasman Glacier, and of the Government surveys, conducted by Mr. Brodrick, of the Godley, Classen, Mueller, and Hooker Glaciers.
Von Lendenfeld's work on the Tasman is that of the most scientific interest, and his book (published in German) is, I believe, a valuable work to those interested in glacial phenomena, whilst the map which he made is (with the exception of one glaring error—viz., the course of the Linda Glacier) a wonderfully correct and beautiful chart of the glacier and its tributaries and surrounding peaks.
Some observations for altitude, taken at the terminals of the Rangitata glaciers by the Hon. J. B. A. Acland during a course of twenty years from 1860, are very interesting, and tend to show that the glaciers are receding. The more interesting of Mr. Acland's observations go to show that in 1866 the altitude at the terminal face of the Clyde Glacier was 3,239ft., and that the point above, where the clear ice was lost in the moraine, was 1,057ft. higher. In 1867 this point was 980ft. above the terminal, and in 1871 only 752ft., thus showing a shrinkage of 305ft. in altitude between these two points in a period of five years. In 1880 Mr. Acland again visited the glacier, but, while being unable to take any measurements,
he remarked a great difference in the appearance of the glacier, which led him to believe that the shrinking was still going on. My own casual observations on the Tasman, Hooker, and Mueller during the past five years bear this out in a decisive manner.
Narrative of the Exploration of the Murchison
It was on the 10th of January of the present year that Messrs. Arthur Harper, H. Montgomerie-Hamilton, James Annan, and myself started from our camp at the eastern base of Mount Cook—close to the Ball Glacier—for the Murchison, whose valley-mouth joins the eastern side of the Tasman Glacier opposite to this point.
Crossing the Tasman Glacier—here some two miles or two miles and a half wide, and mostly covered with morainic detritus—we ascended to a height of 500ft. or 600ft. on the shoulder of the Malte Brun Range, to get a glimpse up the valley from an advantageous point. From here, however, we could but discern the bed of the Murchison River and part of the terminal face of the glacier, some four miles distant; the major part of the glacier-face being hidden by the spurs abutting from the Malte Brun Range. Our object was to work our way to the head of the Murchison Glacier, climb over the saddle depicted on the various maps, into the Tasman Glacier, and so on down to our starting-point, and thus make a complete circuit of the Malte Brun Range. We were provisioned for two days, and favoured with fine weather.
Descending to the bed of the river, we wended our way up the flat. The bed of the river occupies almost the entire surface of the valley, and is composed of unusually small gravel, which has been spread out with remarkable evenness, and is threaded in all directions by streams from the glacier. The incline of the river-bed is very slight, and is probably caused by the lateral part of the Tasman Glacier blocking the whole of the mouth of the valley, and acting as a dam to the shingle, which would otherwise be washed down, leaving the coarser detritus to form a bed at a steeper angle.
About two miles up the valley an immense boulder-fan is met with, formed by a talus of denuded rocks from the Malte Brun Range, and this is accompanied by a fine waterfall, having its source in a secondary glacier in the heights above; and above the glacier again a snow-clad peak (probably one of the peaks of Mount Chudleigh) appears. The whole scene presents a picture of great beauty. Here we lunched, and spent some time examining the interesting features of the spot.
By constant action of the water a cylindrical groove has been worn in the solid rock some 6ft. or 8ft. in depth, 10ft. or
12ft. across, and about 80ft. in height, so that the water descends, as it were, through a half-funnel, and with such force as to project a constant shower of spray (strange to say) in one particular direction only—viz., that immediately opposite the back of the cylinder. Under this spray some plants frequenting the locality (notably the Myosotis) flourish in the abundant moisture, whereas beyond the sphere of its influence they seem but indifferent specimens by comparison; whilst other varieties, not requiring such a constant state of moisture, are affected in a contrary direction, and struggle in vain to rival their brother-specimens on the mountain-side close by.
To this glacier and fall we have affixed the name of “Burnett,” in honour of the only man who had previously visited the valley, and whose sheep-run is most contiguous to the locality.
An infinite variety of subalpine flora is found in the Murchison Valley, and at this time the slopes were gay with the rich blossoms of Ranunculus, Celmisia, Myosotis, and the golden heads of many varieties of the Spaniard. The valley would carry a large number of sheep during the summer months if it were possible to get them up; but I should imagine the risk of having them snowed in during the autumn would be considerable, even were it practicable.
At this point the course of the valley trends to a more northerly direction, the compass reading about north-east, Soon we arrived at the terminal face of the glacier, which by aneroid measurement determined the altitude at 3,700ft. above sea-level. Von Haast gives the figure as 3,540ft.; but it is strange that he makes no mention of a visit to the spot in his work. Possibly he estimated the height from observations taken at the spot where the river joins the Tasman Glacier.
The lower part of the glacier is all moraine-covered, and presents a wall about 200ft. in height blocking the whole of the valley, which appears to be about a mile and a half to two miles in width at this part. The moraine is composed of unusually large polyhedral masses of rock, piled up in mounds and ridges in a state of the wildest confusion, amidst which very few outcrops of ice can be detected. This moraine is one of the roughest I have seen.
Wending our way up the western side of the moraine, we soon arrived at the junction of a second large glacier descending from the Malte Brun Range on our left. This glacier lies in a double basin in the mountain-side, and pours down a steep declivity, bearing with it quantities of morainic matter from above, and, like the Burnett Glacier, is accompanied by a waterfall descending (in this case for some hundreds of feet) from its south-western portion. After obtaining His Excellency's permission, we have named this glacier the Onslow
Glacier, in honour of the present Governor of this colony Here we spent the night, wriggling into our oiled-calico sleeping-bags, on a bed of small gravel in a hallow of the moraine at the junction of the two glaciers, where, though running some risk from falling stones from the ice-slopes on two sides of us, we were protected from the cold breeze which blew up the valley.
We were early aroused in the morning by the persistent attention of several keas, as they hopped around us and even pecked at our sleeping-bags, so tame and unaccustomed to man are they in these parts. Once more shouldering our torturing swags, we proceeded on the western side of the moraine, and ere long descried a third glacier (of the second order), nestling in a comparatively low saddle on our left, and further ahead still a fourth and very large tributary glacier, coming down with a grand sweep into the main body of the Murchison. At first we thought this glacier to be the Murchison itself, as it appeared to compare somewhat with the maps; but on cutting our way up its gigantic lateral ice-slope we discovered our error, for there, a mile away east across the moraine, lay the clean ice of the glacier we had come to explore. The glacier we were now on we named the Cascade Glacier, as its form in its descent from the heights of Malte Brun resembles that of a cascade.
In an hour's time the clear ice was gained; but we were soon in trouble amongst a maze of crevasses on attempting to cross to the opposite side. This system of crevasses appears to be caused by the flow of the ice being faster on the Western than on the eastern side, owing to the immense body of ice brought into this portion by the Cascade Glacier and several similar ones situated parallel to it, and farther north, on the Malte Brun Range.
The eastern side shows very little lateral moraine, for the western declivities of the Liebig Range do not carry such large quantities of ice as the slopes opposite, and denudation is consequently not so great. This fact is worthy of notice, for a similarity occurs in the case of the Tasman Glacier and the western slopes of the Malte Brun Range. I also understand from Mr. Burnett that the eastern slopes of the Liebig Range, at the head of the Jollie River, are clothed with considerable glaciers, whilst still further north (beyond Mount Jukes, which divides the watershed of the Jollie and Cass Rivers) the Huxley and Faraday Glaciers supply the head-waters of the Cass River.
After a futile attempt to cross these crevasses at right-angles to their trend, we struck up the ridges of ice which lay, like the leaves of a half-opened book, between them, until we had reached their extremities, and then struck across to the
western side of the glacier, where we ascended to a point of observation and studied the view before us. Looking in the direction from whence we had come, a magnificent panorama was presented, for we were in full view of the major part of the Malte Brun Range with all its glorious peaks and glaciers. We also noticed that the only distant point visible from this spot was the upper part of Mount Sealy, situate at the northern end of the Ben Ohau Range. The topmost peak of Mount Sefton we had observed from a point farther down the valley. Turning our attention northwards, we began to realise more than ever the immenseness of the Murchison, and at the head of the eighth or most northerly tributary glacier from the west we discerned what we concluded must be the saddle leading into the Tasman. From this saddle a large rocky spur descended into the Murchison, the head of which appeared to be just round its point. The Liebig Range, on which we now were, soon assumed a northerly and then north-westerly direction, enclosing in the curve several tributary glaciers, one in particular, situate at the centre of the curve, being of considerable magnitude.
We now decided to stay out for another night, and make every effort to cross the saddle we had noted, and find a sleeping-place in the rocks on the Tasman side before nightfall. We pressed on up the middle of the glacier, endeavouring fruitlessly to identify the Malte Brun peak or Mount Darwin, whose aspects from the other side were well known to me. When abreast of the saddle we altered our course abruptly and made for it. Crossing a small medial moraine (which took its rise at the end of the rocky spur already mentioned, and was noticeable by its mathematically direct course—indeed, it presented from a distance the appearance of a straight metalled road), we were soon floundering across a perfectly level sloppy field of ice, which was entirely undrained by crevasses, and then commenced the gentle ascent of snow-slopes in soft and dangerous condition. We roped up, to avert danger from covered crevasses, amongst which we began to thread our laborious way. The work was very arduous, and this, added to the fact that one man was suffering extreme distress from exhaustion, and another from an overworked sinew in the leg, made us almost despair of reaching the saddle. To add further to our troubles, a thick mist began to creep over the saddle, accompanied by a keen wind, and we stood in some danger of avalanches, owing to the loose condition of the snow. By dint of the exercise of much perseverance, and by the aid of many rests, however, we ultimately succeeded in zigzagging upwards amongst a perfect labyrinth of bergschrunds and crevasses, and at last crept up the final pinch to our goal.
The scene on the other side of the saddle was enveloped in mist, but after a few moments the fog vanished as if by magic, disclosing directly at our feet a large glacier, with a strange peak immediately opposite to us. We expected to gaze on Mount De la Bêche, Mount Green, Mount Elie de Beaumont, and the Hochstetter Dome, and all the well-known features at the head of the Tasman, and it was not until we suddenly discovered that the flow of the glacier below us pursued a course to our right (whereas the Tasman would have shown a directly opposite course) that we realised we were in full view of the true head of the Murchison Glacier, which commenced at our left, and led down a valley in an easterly direction, curving round the rocky spur (a saddle in which we were now on), and eventually assumed a south-westerly course. The total length of the glacier we estimated at from twelve to sixteen miles—probably nearer the latter figure—and its width from a mile and a half to two miles on the average, thus making it second in size only to the great Tasman Glacier.
We ascended to some rocks on our right, 300ft. above the saddle, and here, building a small cairn, deposited a record of our ascent. From these rocks, looking in a direction north by west, over the top of the strange peak directly opposite, can be seen what can hardly be any other mountain than the Hoch-stetter Dome, whose summit two of us had trodden in the previous autumn. The double dome of snow is a unique and almost unmistakable landmark seen from the Tasman, but I have never observed it before from an immediate southerly standpoint; yet we were agreed as to its identity: and, if we are correct in our conclusion, then glaring errors exist in von Haast's and von Lendenfeld's maps, and also in that issued by the Survey Office in Wellington for the use of tourists.
I am well aware of the danger of making topographical assertions when one is not acquainted with some knowledge of surveying, and where all distances have to be estimated, and the fixing of well-known peaks is uncertain; and I base all my remarks on the topography of this part on the assumption that the peak we observed north by west from our standpoint is the Hochstetter Dome. Did space permit I could adduce many reasons for the assumption, apart from the fact that the peak is well known to me from the Tasman, and that no mountains similarly capped exist in the vicinity.
This, then, being the case, the point on which we now stood must be on the eastern slopes of Mount Darwin, which with the Malte Brun Range is encircled by the Murchison and Tasman Glaciers. At the left of the conspicuous peak over
which the dome is visible, a comparatively low saddle is situated, which must be the true Tasman Saddle, and at the right of the peak another saddle, which must lead into the Whymper Glacier, on the West Coast watershed.
Speaking on this point—viz., the orographical features of the Liebig Range—von Haast says, “Between the Tasman and Murchison Glaciers lies the bold and picturesque Malte Brun Range, appearing like an island, the Murchison Glacier having at no distant date joined the former, and thus surrounded this lofty snow-capped ridge. From Mount Darwin, the convergent range still continues its southern direction, where …. in the Liebig Range the glacier-sources of the River Cass …. are situated.” According to our observations, of course, it will be seen that Mount Darwin has no connection with the Liebig Range, neither is it on the main range, but is enclosed, with the Malte Brun Range, by the Murchison and Tasman Glaciers.
Following with the eye the summits of the Liebig Range from the point of its divergence from the main chain, a short distance east of the Whymper Saddle, a fine array of peaks and glaciers presents itself. Situate in the big bend of the range is one mountain of toothlike form, which presents a remarkably imposing appearance, and seems to drain into the Classen Glacier from its opposite slopes; whilst just to the east of it is situate a low snow-saddle, possibly leading into that glacier. I cannot find this peak marked on any map extant.
Even supposing our conclusions regarding the topography of this locality to be wrong, there must be ascribed a far greater importance to the Murchison Glacier and Liebig Range than that given to it on any existing map. Our aneroid gave the height of our standpoint as 8,300ft., but this would probably be some hundreds of feet in excess of the true height. From the appearance of the saddle leading into the Tasman, and the crevasses around its base, we considered that it might prove impracticable even to a well-equipped alpine party.
Coming down to the saddle again, a decision to return by our upward route was quickly formed, for our distressed man was lying exhausted on the snow, and suffering from a severe attack of vomiting. Some people call this malady “mountain sickness,” believing it to be brought on mainly by rarity of the air, and it is an evergreen subject for discussion amongst climbers; but most practised mountaineers incline to the belief that the sole cause of it is undue exertion when out of training: and in this case such a conclusion would be justifiable, for the subject affected had not been a week off ‘board-
ship, and was in anything but a fit condition for such exertion as we had undergone.
We had but three hours of daylight left, but made good time down, keeping to our upward tracks, and, with the exception of a lucky escape from a small avalanche which crossed our path behind us, and an occasional half-tumble into a thinly-covered crevasse, reached a point beyond the junction of the Cascade Glacier an hour after dark, where we bivouacked for the night, and next morning dragged our weary limbs out of our sleeping-bags at 4.30 a.m., and reached the Ball Glacier camp on the Tasman by noon.
Owing to shortness of provisions and the distressed condition of our party, it was imperative that we should return to camp as soon as possible, so that our topographical observations from our highest point were necessarily hurried, and I submit my suggestions with some diffidence, though we ourselves feel satisfied that they will be verified by future surveys.
Points of Scientific Interest.
The points of scientific interest which arise in an excursion of this nature are manifold, and the Murchison Glacier, with its immediate surroundings, offers a splendid field to the student or lover of nature.
To the geologist it exhibits sections laid bare for thousands of feet, and illustrations of the action of water, in its various forms of snow, frost, rain, ice, or stream, are plentiful on every hand. One can trace the history of a stone from the point of its denudation as an angular and many-sided block, through all its rough usage, grinding, and attrition during its years and years of travel down the glacier, and imagine it being gradually rolled over and over amongst its fellows, until, many decades after, it is brought up, rounded and smooth as a marble, by the Tasman Glacier, which bars its further course.
The many boulder-fans and tali of débris one meets with in the lower part of the valley naturally lead one to think of the history of their formation, which is, I believe, mostly accomplished by the agency of snow, and not so much by that of water as is popularly supposed. In the winter-time all the gullies that supply these fans are filled with snow (which is subject to a certain extent, and under certain conditions, to the same laws which govern the motion of a glacier), and, as denudation of the rocks proceeds, the detached fragments are precipitated on to the surface of the snow, and glide—where the angle of the descent is steep enough—and are carried down by snow-slips and avalanches in the spring-time, and deposited as the snow melts in the summer.
Fans composed of small shingle one can see being built up
by water during flood-time. almost anywhere, but these immense blocks cannot have been coaxed or wheedled down by the comparatively small trickle of water which meanders amongst them. The western side of the valley is particularly rich in illustrations of the deposition of rocks by snow.
To the botanist a field both novel and various is offered, whilst the artist might find scenes of the rarest beauty and grandeur.
To the entomologist many kinds of insects not met with elsewhere abound. The grasshopper family predominates, but several kinds of butterflies are to be seen. The insects which I have observed at the highest altitudes are a black butterfly (Percnodaimon pluto), with yellow spots on the wings, whose flight is sluggish and heavy; and a black weta (Hemideina), having a body 1in. in length, but with hair-like antennÆ nearly 2in. long. These latter insects are found far above the snowline, and appear to exist where even lichens are rarely met with. But the ubiquitous blue-bottle (Calliphora) soars even higher, for I have seen these flies at over 9,000ft., in places where the snow-line would be 4,000ft. below. Some very fine green lizards (Naultinus) are also to be found in the locality I have seen a specimen, I should think, 18in. long.
Standing at the head of the Murchison Glacier one can read the history of its marvellous conception and growth—from the crystalline snowflake to the dull and absorbent condition, then into the névé, and by gradual infiltration, refreezing or regelation, and consolidation, into the glacier “granule,” and by continued pressure into that hard black ice which one meets with in the middle and lower parts of a glacier, laden in lines from well-defined sources with its burden of millions of tons of rocks, shed by denudation from the adjacent mountains, and being borne on with slow but irresistible force to their resting-places on the lateral or terminal moraines.
The theory of glacier-motion naturally occurs to one in such a locality; and this subject opens out a large field for scientific observation and thought, which it would be imprudent to encroach too far upon in a paper of this nature. My own reading and observation lead me to think that the only theory worthy of credence is that of gravitation and pressure from above, and, in some instances, lateral pressure through contraction of the bed of the glacier. It has always struck me that the motion of a glacier may be most aptly compared to that of water in the bed of a river, that flows slowly in places, and is broken up and flows more swiftly over places where its bed inclines at a steeper angle from the horizontal. From careful observations by many men of note, it is well known that over beds inclining at the same angle a greater
body of ice will flow more quickly than a lesser—an axiom which holds good with water. The simile is a favourite one of Tyndall's, Geikie's, and Forbes's, but is of very ancient origin amongst glacier writers.
The altitude of the Hooker Glacier at its head is 8,580ft. at its terminal face, 2,882ft.; length, seven miles; and width nearly one mile; and its average descent per mile, 665ft. Mr. Brodrick has endeavoured to obtain some idea of the rate of its progress at a point near the terminal face, and his observations give an average summer rate of 4.33in. a day. Allowing for the retarded winter motion, the result for the year would probably be brought down to under 4in. a day.
The altitude of the head of the Murchison would probably be 6,500ft., though the ridges on either hand are something like 8,000ft., and its terminal 3,600ft.; its length, say, is fourteen miles, and width a mile to a mile and a half; and the average descent per mile, 207ft. Assuming Mr. Brodrick's measurements of the Hooker to the correct, if we took the Murchison by comparison we should probably arrive at a much slower rate of progress. But, of course, this is little better than guesswork, for we cannot, except at the terminals of these glaciers, form any sound estimate as to their depth. Only in some places, where their lateral parts are laid bare whilst passing a gorge in the mountains at their sides, or by measuring the depth of their crevasses, can we hope to glean some insight into the question.
By the former method I have attempted in a rough way to arrive at a conclusion regarding the depth of the Tasman Glacier at a point some ten miles from the terminal face, where a large section of the ice is laid bare, showing in a most interesting manner a stratification of the ice, and the distortion it has undergone during its downward journey. On the surface of the glacier at this point the aneroid gave a reading of 4,500ft., and at the foot of the exposed ice of 4,000ft., and here was formed an ice-cave by the entrance of a mountaintorrent at a steep angle of descent from the slope of Mount Chudleigh, in the Malte Brun Range. One could penetrate downwards into the cave for a short distance only, owing to darkness, danger from falling ice, and from the impetuous nature of the torrent; but it is reasonable to estimate, from what observations I could make, that another 100ft. of thickness could be attributed to the ice, making 600ft. for certain. Now, the outlet of the river is 2,450ft. above sea-level; and the surface of the glacier at the point in question 4,500ft.; therefore the ice could not exceed in thickness the difference between these figures, or 2,050ft. But we must consider the slope of the glacier-bed. That of the surface of the glacier inclines on the average from the terminal face (250ft. above the outlet of
the river) at 180ft. per mile. As the glacier advances to its melting-point it no doubt decreases in depth, despite the fact that it is protected from the rays of the sun to a large extent by the load of detritus which it carries; and the probabilities are that, if we could by any means get at the bed of the glacier ten miles from its terminal, we should find that 130ft. per mile would be sufficient to allow for the rise of the valley-bottom, in which case we could add another 150ft. to our 600ft. arrived at, making the depth of the glacier 750ft. at a point close to its side; and it is only reasonable to suppose that the bed of the glacier would dip towards its centre, so that probably a still greater thickness obtains in its middle portion. I imagine it would be a very difficult matter to obtain measurements of the depth of crevasses, as their sides are seldom or never quite vertical for any great depth.
The stratification of glacier névé is a further subject of interest, and whilst in the upper part of the Murchison we were favoured with a view of some sections of consolidated névé which had been disturbed by avalanches, exposing very markedly the stratification and strata of impure snow which accumulate on the level of each season's surface from dead insects and impurities and floating matter in the atmosphere during the warmer months of the year. Whether the strata in this instance marked the summer and winter seasons, or were occasioned by shorter periods of fine weather and snowfalls alternately, I am unable to say.
[Note.—In January, 1891, the Government survey of the Murchison Glacier was completed, confirming the topographical conclusions contained in this paper as correct.— G. E. M., Christchurch, 17th March, 1891.]