Art. LXVIII.—Notes on Dr. Haast's supposed Pleistocene Glaciation of New Zealand.
[Read before the Wellington Philosophical Society, 15th August, 1874.]
In the course of the last year's proceedings of this Society I had the honour of submitting to it some observations upon the remains of extensive but now extinct glaciers, which occur in the principal valleys of the great mountain range of the South Island, in which I attributed the origin and subsequent disappearance of the glaciers which have left these evidences of their former existence, to oscillations in the level of the land. As I then pointed out, the views embodied in my paper differ materially from those propounded by Dr. Haast, on the same subject, in a report to the Provincial Government of Canterbury in 1864; but as he has lately reasserted the views contained in that report in their entirety, I propose now to examine them at some length, in order to show, more fully than I attempted to do in my last paper, the grounds upon which I differ with him; and I do this the less unwillingly, because, in the first place, Dr. Haast has challenged criticism, and because, in the next place, the right determination of the question at issue between us is of considerable importance in connection with our enquiries into the existing physical features of these islands.
My own views, as stated in my paper of last year, are,—That at the close of the miocene period the South Island generally began to rise, and that its central mountain chain ultimately attained an elevation exceeding its present altitude above sea level by some 4000 or 5000 feet. That during the period of maximum elevation all the main valleys in this central range were occupied by glaciers, each of which was, roughly speaking, proportionate in size to the altitude of the mountains and to the extent of the drainage system in which its own particular valley originated, and extended down its valley to a distance proportionate to its own mass. That this period of elevation was followed by a depression to an extent which, probably, exceeded the maximum elevation above mentioned. That, as a result of this depression, the glaciers occupying valleys in those parts of the range which had not attained, during the period of maximum elevation, a greater altitude than 13,000 to 14,000 feet above sea level disappeared. And that although, in postpliocene times, there had been a re-elevation of the land, during which the glaciers now existing in the valleys radiating from Mount Cook again advanced, occupying, with slight variation,
their present positions ever since, yet that this re-elevation was not sufficiently great to cause the formation anew of glaciers in any parts of the range in which they do not now exist.
The views propounded by Dr. Haast are, as I am about to show, entirely different, except in so far as he has associated the glaciation mentioned in his report with an elevation of the land. As will be seen in the sequel, our first great point of difference is as to the time when the glaciation to which the glacier remains in question are referable took place; for, whilst I contend that it occurred during an elevation of the land commencing at the close of the miocene, and in all probability continued during a large portion of the pliocene period, he states that these islands were entirely submerged during and until the close of the tertiary epoch, and that the glaciation mentioned in his report (and of which he, also, considers the existing glaciers in the Mount Cook valleys to be continuing remnants) began almost coincidently with the re-emergence of the land, increasing in intensity with increasing elevation.
Our next great point of difference is as to the extent of the glaciation itself, for, whilst I contend that it never exceeded that which would occur, in the latitude of New Zealand, in a range of mountains averaging 14,000 feet in height and exposed to physical conditions similar to those which now exist, except, of course, in parts of the range which in the general rise of the land would attain an elevation materially exceeding that altitude, Dr. Haast contends that it was an universal glaciation, similar to that which now exists in Greenland and in the antarctic lands. He tells us, indeed, in the report in question (and throughout this paper I intend to quote his own words, merely changing the present to the past tense where such a course will best fit in with my own language), “that it was not necessary for him to give a picture of the desolate aspect of the country in those pleistocene times, but that, when recalling the descriptions of Greenland by Dr. Kane, and of other arctic and antarctic explorers, it brought vividly before his mind that the South Island during that era would have presented a very similar appearance; or (he enquires) might it not more appropriately be compared to the inner Thibetan glacier region as it at present exists ?"
But differing materially, as we do, both as to the time at which the glaciation in question occurred, and as to the dimensions which it attained, we differ still more widely as to the causes of its origin and subsequent disappearance.
After having stated, as above extracted, the exact character of the glaciation in which he alleges the South Island to have been involved, in pleistocene times, the learned doctor proceeds to give the following as his views of the “causes” which brought it about, and of those which afterwards led to its extinction, heading that part of his report which is specially devoted to this
question with the words “Causes of the pleistocene glaciation of New Zealand.” For convenience of future reference I have numbered the several paragraphs as they occur in the report; they are as follows:—
"Causes of the Pleistocene Glaciation of New Zealand.
“During the tertiary period, the Southern Island of New Zealand was repeatedly submerged, and extensive strata of calcareous, tufaceous, and argillaceous sandstones, greensands, marls, limestones, and shale, with beds of lignite, were deposited. The country emerging again, the physical feature was a high mountain chain, plateau-like, but with depressions existing before the tertiary submergence, but now partly obliterated, running generally either on the junction of two formations, on the lines of faults, or on the break of bold anticlinal folds.
“As soon as the country had risen so high as to reach the line of perpetual snow, the accumulation of névés began, which were the more considerable as glaciers and large rivers had not yet begun their task of ridge making in contradistinction to the action of waves and currents of the sea on submerged lands, which tends to wear off all eminences, filling the submarine valleys with the débris.
“The configuration of the area now forming the Canterbury plains would have been a broad arm or channel of the sea running along cliffs of tertiary rocks from Timaru to Double Corner, and surrounding Banks Peninsula as an island. The waters derived from atmospheric sources had already begun, during the emergence of the land, to open an outlet for themselves from the higher regions by clearing the natural watercourses, but had only in a minor degree attacked the tertiary strata, filling the valleys in favourable localities as high as 4000 feet above the level of the sea.
The névés, considering the insular and peculiar position of New Zealand—its principal range or back-bone running from S.W. to N.E., thus lying at a right angle to the two prevailing air currents, the equatorial north-west and the polar south-east, both bringing moisture with them—would soon have attained an enormous extent, and would have considerably lowered the line of perpetual snow, even had not the land been raised to a higher elevation than at present. The consequence would have been that glaciers of much larger extent would have descended down the natural outlets, grinding down the rugosities of bottom and sides.
“The action of the glaciers beginning to lay open the rocks of the higher ranges, would soon offer sufficient material for moraine accumulations, first on the glaciers themselves, and afterwards at their terminal faces.
“The scooping action of the ice having once begun to eat into the plateau-like range, not only in the main course of the glaciers, but also in the
lateral valleys becoming more extended from day to day, would furnish more and more material for the formation of huge moraines.
“Let us now consider what may have been the action of the waters during the emergence of the island upon the region over which at present the Canterbury plains extend.
“In the first instance the waves of the sea would have acted upon the tertiary strata, undermining and destroying them, till the débris of the falling cliffs would have formed a protecting wall at their foot, although frequent oscillations and changes in the ratio of elevation or subsidence may have caused many diversities.
“The tertiary beds, risen above the level of the sea, would soon have been eroded by the action of the streamlets or torrents descending from the higher regions, and growing larger with the continuance of the upheaval and becoming more numerous, bringing down with them gravel and sand, more effectually increasing their eroding power.
“At the same time the glaciers, descending from the enormous snow fields, covering the large plateau-like ranges, began to fill all the existing valleys to the plains in a fan-like shape.
“Of this occurrence, however, we have very little proof, if it be not that the older glacial deposits in the bed of the Rangitata, several miles below the gorge, and some others rising above the plains, between the Malvern Hills and the Waimakariri, belong to that period.
“High on the ranges, near the plains, the proofs of still greater glaciation of the island are visible in the in worn sides; even the ranges themselves, in their summits and configuration, bear distinctly marks that their very form is attributable to such an almost universal glaciation. Moreover, it is evident, by judging from the study of our present glaciers, that these enormous névés, and ice masses, covering with an uniform sheet the higher regions of the whole island, would not offer much material for the formation of the plains till the glaciers had begun their task of ridge-making, which took place principally in the second epoch of the glaciation of this island.
“The glaciers had so far retreated that they were only confined to the principal valleys, and of these such clear signs are found, as soon as we enter the valleys between the ranges leading from the Canterbury plains into the Southern Alps proper, that their power and its effects are unmistakable. And as now these glaciers, as shown above, brought a much greater amount of débris from the disintegration, destruction, and weathering of the mountains with them, they did not form only enormous moraines at their sides and their terminal end, but the torrents issuing from them carried down a great amount of material in the form of boulders, shingle, sand, and glacier mud, the latter being derived from the triturating effects of the ice on the sides and bottom of
the channel of the glaciers. These torrents now began to raise rapidly their beds, and filled, by the continuous shifting of their regular and flood channels, all the inequalities of the surface of the lower regions exposed by the emergence of the sea. From that moment the formation of the Canterbury plains began.
“Moreover, a momentum of high importance must not be lost sight of, namely, that all the rivers which traverse the Canterbury plains have their sources in formations which consist principally of shingle and sand-making rocks, thus affording all the necessary elements for effecting this purpose.
“Ascending the Canterbury plains we can easily trace their continuation up the valleys, the angle of the dip of the loose deposits rising the more we approach the terminal moraines of these pleistocene glaciers. Amongst those which form our plains, I have traced all the principal ones, and I shall give in the sequel the length and the position of their terminal face.
“It will be seen by that list that at least two of those glaciers (not yet having examined the upper valley of the Waimakariri) were so large that they sent side branches into the valley of the Ashburton, so as to form in that valley one of the largest ice streams of the whole system, which thus gives the key to some peculiarities of the Canterbury plains, and which, without the knowledge of this important fact, would be very difficult to explain.”
The foregoing paragraphs contain all that is to be found in the report in question, or; indeed, so far as I am aware, in any of Dr. Haast's writings, as to the cause of the alleged pleistocene glaciation of New Zealand, although its existence and extent, as stated in this report, have been constantly referred to and assumed as proved, in his subsequent papers upon the geology and physical geography of the South Island. I therefore thought it proper to quote these passages at full length, in order not only to prevent any suggestion of misinterpretation, but also to ensure a more complete understanding of the criticisms which I propose to apply to the propositions deducible from them. At first blush, indeed, it seems difficult to believe that Dr. Haast really intended his readers to accept the statements contained in these passages in their plain literal sense, inasmuch as the geological and other physical changes which he has crowded into the pleistocene period are of astonishing magnitude, more especially when we bear in mind that New Zealand is separated from the nearest continental land, from which it could draw any portion of its present organic features, by not less than 1200 miles of ocean. But the language is too clear to permit of any other than the literal sense, and, therefore, I have been compelled to adopt that sense in dealing with the questions under discussion. Now, upon a careful consideration of the above quoted passages, we find that certain propositions, in the nature of postulates, are laid down
for our acceptance, which, so far as they are material for the purposes of my own argument, may be briefly stated as follows:—
That the Southern Island of New Zealand was repeatedly submerged during the tertiary period.
That its ultimate re-emergence took place at the close of that period, and that it gradually assumed the appearance of “a high mountain chain, plateau-like, but with depressions existing before the tertiary submergence, which were then partly obliterated, running generally either on the junction of two formations, on the lines of faults, or on the break of bold anticlinal folds.” So far as I can comprehend all this, I assume it to mean, that the re-emerged land, limited in the first instance to the area of the present mountain range, exhibited the aspect of a plain of marine denudation; that the surface irregularities which had existed prior to its latest submergence had been partly obliterated by submarine denudation; and that, as the land rose en masse, it assumed the appearance of a flat-topped mountain range, protected, in great measure, from ordinary terrestrial denudation by a pall of perpetual snow extending to the water's edge.
That, “looking to the insular and peculiar position of New Zealand, the névés” (by which, I presume, Dr. Haast means mere accumulations of snow, without the ordinary technical sense in which the word is used) “soon attained an enormous extent, and considerably lowered the line of perpetual snow.” Leaving the first part of this proposition for future comment, I must confess my inability to comprehend how accumulations of snow, however enormous, can lower what is generally understood as the snow line, and it becomes, in the present instance, the more difficult to comprehend, for, as we have seen, Dr. Haast leads us to understand, by comparing his asserted glaciation with that of Greenland, etc., that the snow line at the time in question was coincident with sea level.
That as a result of the suggested elevation, and of the operation of the so-called “causes” above quoted, the islands of New Zealand became involved, in pleistocene times, in a glaciation similar to that which now invests Greenland and the antarctic lands, or the inner Thibetan glacier region.
That when the land of the South Island had risen so high as to reach the line of perpetual snow, “the configuration of the area now forming” (doubtless “occupied by”) “the Canterbury plains would have been a broad arm or channel of the sea, running along cliffs of tertiary rocks from Timaru to Double Corner, and surrounding Banks Peninsula as an island.”
It will, of course, be seen that this latter proposition conflicts in some degree with those which purport to define the character of the suggested glaciation, as mentioned in the foregoing quotations from the report, for it would seem to involve an implication that the “line of perpetual snow” stood
somewhere above, instead of being coincident with, sea level. But, although I am unable to reconcile the apparent discrepancy, I have thought it necessary to call special attention to this particular proposition, as it contains an admission of considerable importance to my own arguments.
Such, then, are the propositions which Dr. Haast lays down for our acceptance, without, however, condescending to offer any arguments in support of them, or to state any relevant facts from which they could be independently deduced, and I need not say how unfortunate and embarrassing this is in connection with any discussion of the questions at issue between us. In a scientific enquiry “a point which can be proved should not be assumed,” and it was Dr. Haast's undoubted duty, when laying down such propositions as those which are fairly deducible from his report, to have stated, clearly and definitely, the nature of the evidences which had led him to adopt them. But, notwithstanding these disadvantages, and in spite of the difficulty of assigning any meaning which should be consistent with received geological principles to much of his language, I propose to examine the above stated propositions at some length. In the first place, however, in order that the character of the glaciation with which Dr. Haast has chosen to invest the islands of New Zealand in pleistocene times may be understood, I extract the following descriptions of the present glaciation of Greenland, and of that of the antarctic lands, from authors of undoubted authority:—
“Whatever it may have been when Captain Inglefield saw it a year ago,” says Dr. Kane, speaking of Greenland even before the close of the northern summer, “the aspect of this coast is now most uninviting. As we look far off to the west, the snow comes down with heavy uniformity to the water's edge, and the patches of land seem as rare as the summer's snow on the hills about Sukkertoppen and Fiskernaes. All the back country appears one great rolling distance of glacier.”
Mr. Geikie, in his work on “The Great Ice Age,” page 54, thus speaks of the existing glaciation of Greenland:—
“We have now acquired some knowledge that bears upon the origin of the Scottish till, but we shall gather yet further aid in our attempts to decipher the history of that deposit by taking a peep at some arctic country. For this purpose we cannot do better than select ice-covered Greenland. That desolate region of the far north, despite the bleak and barren aspect of its coasts, and the horrors of the ice-choked seas that must be traversed to reach its more northern shores, has nevertheless been frequently visited by daring navigators, who have pushed their investigations many hundred miles north of the Danish settlements. The accounts which they give are chiefly taken up with descriptions of the wild ice-bound coast of Greenland, few attempts having been made to penetrate into the interior. But that cannot be said to be altogether a terra
incognita, for although it has never been and probably never will be traversed, yet enough is known to leave us in little doubt as to the general character of these unvisited desolations. The western shores of Greenland have been traced northward from Cape Farewell, in the latitude of the Shetland Islands, to beyond the eightieth parallel. The eastern and north-eastern coasts have not been so continuously followed, but our knowledge of these has been considerably increased during recent years, thanks to the exertions of German and Swedish geographers. The superficial area of Greenland cannot be less than 750,000 square miles, so that the country is almost continental in its dimensions. Of this great region only a little strip, extending to 74° north latitude, along the western shore is sparsely colonised; all the rest is a bleak wilderness of snow and ice and rock. The coasts are deeply indented with numerous bays and fiords, or firths, which, when traced inland, are almost invariably found to terminate against glaciers. Thick ice frequently appears too, crowning the exposed sea cliffs, from the edges of which it droops in tongue-like and stalactitic projections, until its own weight forces it to break away and topple down the precipices into the sea. The whole interior of the country, indeed, would appear to be buried underneath a great depth of snow and ice, which levels up the valleys and sweeps over the hills. The few daring men who have tried to penetrate a little way inland from the coast, describe the scene as desolate in the extreme—far as eye can reach nothing save one dead, dreary expanse of white. No living creature frequents this wilderness —neither bird, nor beast, nor insect—not even a solitary moss or lichen can be seen. Over everything broods a silence deep as death, broken only when the roaring storm arises to sweep before it pitiless blinding snow.”
As regards the antartic lands, Mr. Geikie says, at page 101 of the same work:—
“Sir J. C. Ross' striking account of the mighty ice sheet under which the Antarctic Continent lies buried, gives one a very good notion of the kind of appearance which the skirts of our own ice sheet presented. After reaching the highest southern latitude which has yet been attained, all his attempts to penetrate further were frustrated by a precipitous wall of ice that rose out of the water to a height of 180 feet in places, and effectually barred all progress towards the pole. For 450 miles he sailed in front of this cliff, and found it unbroken by a single inlet. While thus coasting along, his ships (the Erebus and Terror) were often in danger from stupendous icebergs and thick pack ice that frequently extended in masses too close and serried to be bored through. Only at one point did the ice wall sink low enough to allow of its upper surface being seen from the masthead. Ross approached this point, which was only some fifty feet above the level of the sea, and obtained a good view. He describes the upper surface of the ice as a smooth plain shining like
frosted silver, and stretching away far as eye could reach into the illimitable distance. The ice cliff described by Ross is the terminal front of a gigantic mer de glâce, which, nurtured on the circumpolar continent, creeps outward over the floor of the sea until it reaches depths where the pressure of the water stops its further advance by continually breaking off large segments and shreds from its terminal front, and floating these away as icebergs.”
Mr. Darwin, speaking of islands far to the north of the South Polar continent, tells us (at page 248, tenth thousand of the Naturalist's Voyage), that, “considering the rankness of the vegetation in Terra del Fuego, and on the coast northward of it, the conditions of the islands south and south-west of America is truly surprising. Sandwich land, in the latitude of the north part of Scotland, was found by Cook, during the hottest month of the year, covered many fathoms thick with everlasting snow, and there seems to be scarcely any vegetation. Georgia, an island ninety-six miles long and ten broad, in the latitude of Yorkshire, in the very height of summer is in a manner wholly covered with frozen snow. It can boast only of moss, some tufts of grass, and wild burnet; it has only one land bird, yet Iceland, which is 10° nearer the pole, has, according to Mackenzie, fifteen land birds. The South Shetland Islands, in the same latitude as the northern half of Norway, possess only some lichens, moss, and a little grass; and Lieutenant Kendall found the bay in which he was at anchor beginning to freeze at a period corresponding with our 8th of September. The soil here consists of ice and volcanic ashes interstratified; and at a little depth beneath the surface it must remain perpetually congealed, for Lieutenant Kendall found the body of a foreign sailor, which had long been buried, with the flesh and all the features perfectly preserved.”
I am not in a position to quote any condensed description of the inner Thibetan glacier regions as they at present exist, nor am I prepared to offer any description of them of my own construction, not having Mr. Godwin Austen's work before me; but, so far as I can recollect, a description of those regions would not materially differ, as regards the glaciated aspect of the country, from those which I have already extracted in relation to Greenland and the antarctic lands, and it would certainly be less applicable than they are, to the glaciated aspect of an island in which the ice sheet was bounded only by the waters of the sea.
Now, it will at once be seen that, if the statements made and the picture drawn by Dr. Haast respecting the glacial condition of New Zealand in pleistocene times be founded in truth, the deposit and accumulation of snow, and the formation of glaciers upon the newly-emerged land of the South Island, must have commenced very soon after the land had risen above sea level. That this is, in effect, Dr. Haast's own conception is shown by the
language of the 8th and 9th paragraphs above quoted, although in the latter he certainly mentioned “plains,” the formation of which, however, had not even commenced at that time, if we are to rely upon the statements in paragraphs numbered 3 and 12.
But before proceeding with the more full consideration of the suggested glaciation, I propose to deal with the first and second propositions above stated. In doing so, following in this respect the course adopted by Dr. Haast himself, and giving him the advantage, for the present, of leaving the North Island altogether out of the discussion, I intend to limit myself to a consideration of the physical features of that part of the South Island which is comprehended within the original boundaries of the Province of Canterbury, for it will have been noted that, although Dr. Haast speaks of his supposed glaciation as having involved the whole of New Zealand, his report does not contain a single reference to any part of it outside of the special district above mentioned.
Now, a glance at any map of the South Island, indicating its political divisions in 1864, will show that the district referred to is traversed from north to south by the central portion of the great mountain range which occupies the western side of the island, and that near the southern extremity of the district this range culminates in Mount Cook, estimated at upwards of 13,000 feet in height, whilst it has, otherwise, an average general elevation of from 8000 to 9000 feet. At the distance of about thirty-five miles to the eastward from the foot of this main range is Banks Peninsula, a volcanic mass, stretching from west to east some thirty miles, with an average breadth of thirteen to fourteen miles, its highest summit being, I believe, 2800 feet above sea level, whilst the average general elevation does not exceed 1800 feet. This mass of hills contains numerous bays, inside of which the slopes are usually very steep, constantly presenting abrupt escarpments.
Stretching from Timaru in the south to Double Corner in the north, a distance of about 130 miles, interrupted only at its junction north and south with the western end of Banks Peninsula, we find a low coast line, between which and the base of the great mountain chain lie the Canterbury plains, which rise gradually from sea level until they reach, at the foot of the mountains, an elevation varying from 800 to 1000 feet—in this respect presenting very much the character of the talus-like plains of Chili, as described by Mr. Darwin in his notes on the geology of South America. Traversing these plains from west to east are five large rivers, named the Rangitata, Ashburton, Rakaia, Waimakariri, and Ashley, which, with their tributaries within the range, effect the entire drainage of the eastern side of the main chain for a length of about 150 miles, their falls, for the greater part of the distance through the plains, averaging twenty-eight feet per mile.
These rivers are liable to great floods, arising from causes similar to those which affect the head waters of the Rhone, and the quantity of shingle and silt which they then carry to sea is enormous. The plains are composed of river alluvium, in a deposit which is evidently of considerable thickness, for, except at points where the larger rivers which traverse them have cut through these deposits near their own debouchures from the mountain range, the foundations upon which they lie are nowhere observable.
As will have been noticed, Dr. Haast speaks of the surface materials composing these plains as covering the foundations upon which they lie, with an almost uniform gradient, which I have assumed to mean, that their surface slopes almost uniformly from the most elevated parts near the foot of the mountains to the level of the sea, a point of great importance in connection with any enquiries into the manner in which these deposits were originally spread over the area which they now occupy. The character of the country, both in the neighbourhood and to the southward of Timaru, is sufficiently given in an extract from another report of Dr. Haast's, which will be found in the sequel, and, therefore, need not further be referred to here.
As regards the indigenous vegetation of the district under consideration, I may state, generally, that, with the exception of occasional but by no means common or extensive patches of forest, its eastern side (taking from the summit of the dividing range) supports only grasses and other herbaceous plants, whilst the whole of its western side, below sub-alpine level, is densely clothed with luxuriant forest. The surface of Banks Peninsula is pretty evenly divided between grass and forest land, the latter probably predominating. The flora of the South Island is somewhat less rich in genera and species than that of the North Island, and would, probably, not yield more than 750 species of flowering plants, of which one-fifth would be common to New Zealand and Australia, and one-tenth to New Zealand and South America, whilst not less than 500 species would be peculiar to New Zealand. But it must also be borne in mind that the major part of the flora has a semitropical aspect, inconsistent with the probability of its co-existence with severe glacial conditions, many of the most hardy plants being unable to withstand the rigour even of an English winter.
As is well known, the terrestrial fauna of New Zealand consists almost exclusively of birds, and of the 150 species which may be considered as truly belonging to New Zealand, there are but few which are not found in the South Island. Amongst those which occur there I may particularly mention the two species of wingless birds peculiar to the South Island, namely, Apteryx oweni and Apteryx australis, as well as the Ocydromus australis, and the singular Stringops habroptilus, in the first of which the wings are incomplete, and in both are useless for purposes of flight. I must also, in this connection, mention
the now extinct Dinornithidœ, of which Dr. Haast himself assures us that a large number of species existed during pleistocene times. The climate of the South Island is remarkably good, every species of temperate fruit and a large number of plants which require to be cultivated under glass in England flourishing luxuriantly.
Such are the existing surface features of a tract of country which, if we are to believe Dr. Haast, was subjected, in very recent geological times, after repeated submergences, and when (as he assures us) its elevation above sea level was much less than it is at present, to a glaciation as rigorous as that of Greenland and the antarctic lands.
Returning now to the quotations already made from the learned doctor's report, let us enquire more closely into the geological and other changes which he calls upon his readers to believe that the district in question has undergone since the close of the tertiary period. In the first place, we are told that the whole South Island has risen not less than 13,000 feet above sea level; then, that almost immediately upon and during the continuance of its emergence it became subjected to, and then remained for a large though indefinite period involved in, a glaciation of the character already frequently alluded to; and, lastly, we are required to believe, that it must have acquired all its present surface conditions within the same period. And yet, in the teeth of all this, and in spite of the assertion in paragraph 3, that during the progress of the alleged glaciation “the configuration of the area now occupied by the Canterbury plains must have been a broad arm or channel of the sea, surrounding Banks Peninsula as an island,” the learned doctor has, in a recent address, as President of the Philosophical Institute of Canterbury, whilst reaffirming in its entirety the report of 1864, absolutely repudiated all idea of elevation of the area occupied by the Canterbury plains, either during his glacial period, or during post-pliocene times generally. His language is as follows:—
“If elevation had taken place during the postpliocene or glacier period, Banks Peninsula would certainly show this most conspicuously; but what does a close examination of that interesting isolated volcanic region reveal to us? We observe no trace of marine action, except the result of a slight oscillation of about twenty feet, by which the peninsula has been raised after undergoing probably a similar submergence. It is true that its lower portion in several localities, up to 800 feet, is covered more or less with silt—a fine loam—which, in many instances, is a true slope deposit, partly derived from the decomposition of the rocks in sitû, or partly brought down from higher regions by running water. Moa bones and pieces of small land shells have been found in these deposits, of which there are many splendid sections to be examined, but nowhere the least sign of marine life could be detected in them. This fact alone shows that the emergence theory has not the least foundation;
on the contrary, from the nature of these silt beds and their partial denudation, we might conclude that the peninsula has undergone a depression since they were deposited. Had a rise of the ground taken place, by which the Canterbury plains had emerged from the sea, we certainly would find the proof of it along the slopes of the peninsula, in the form of raised beaches, deposits of sea shingle, and sand with recent marine shells, but nowhere is a trace of such easily recognisable beds to be found, and thus, even assuming that the clear and undeniable data which the Canterbury plains present as to their origin were not in existence, the character of the silt deposits on the slopes of Banks Peninsula, and the absence of recent marine beds, would at once compel us to reject Captain Hutton's new theory as incorrect in all the issues.”
In view of the statements contained and the theory propounded in the report of 1864, all this is very incomprehensible, for if no elevation has taken place, even since the period when the configuration of the area now “occupied by the Canterbury plains was a broad arm or channel of the sea,” I would ask the learned doctor to account for the astonishing fact, asserted by himself, that the higher parts of the foundations upon which the surface materials of these plains are deposited, “consisting,” to use his own words, “of palæozoic, volcanic, and tertiary rocks, which, prior to the postpliocene elevation of the land, composed the former sea bottom,” happen now to be exposed at the debouchures of the great rivers which traverse the plains, at an elevation varying from 800 to 1000 feet above the level of the sea, towards which the superimposed materials slope “with an almost uniform gradient"? *
W. T. L. Travers.
18th February, 1875.
[Footnote] *Since the foregoing paper was read, my attention has been called to the following passages, the first in Dr. Haast's recent address, and the second in a report on the geology of the Canterbury plains, presented by him to the Superintendent of Canterbury in 1862:—
[Footnote] Extract from Address.
[Footnote] “But a still more formidable objection to Captain Hutton's hypothesis presents itself: If the Canterbury plains were of marine origin, the beds of which they are composed would have preserved some traces of it; but, although we have clear sections, several hundred feet high, in almost every river, their fluviatile character is unmistakable. The boulders, shingle, gravel, sand, and ooze are all deposited as a river torrent would place them, according to their form and size, and according to the greater or less amount of water being brought down. The peculiar character of surf shingle is nowhere exhibited, but all the pieces of stone have the subangular form so peculiar to river shingle. Marine fossils are missing throughout.”
[Footnote] After referring to the circumstance that, at the foot of the Urunui Mountains forming the Southern Alps, large deposits of boulders would necessarily occur, he says: —“The Canterbury plains, formed by these deposits, are 112 miles long and on an average 24 miles broad, and consist for some miles inland, along the coast line, of alluvium brought down by the rivers which intersect these plains, and which, for about ten miles from their mouths, flow above the present level of the plains, resembling in this respect the Adige and the Po.
[Footnote] “About nine or ten miles from the mouths of the rivers a change occurs, and, although the beds of the glacial streams are still broad, they begin to cut into the loose deposits of the plains. Terraces are formed, which, on the eastern side of the plains, near the base of the mountains, are often 300 feet above the level of the rivers, and consist of from four to six distinct and perfect terraces rising one above the other. At sudden curves in the rivers (which shift their channels with almost every heavy fresh) these terraces are often destroyed, and beautiful vertical sections are exposed, showing clearly the nature of the deposits by which they have been formed. There is, in the first place, generally a capping of well-stratified shingle and sand sloping insensibly to the sea; below this we find different beds of boulders, for the greater part rounded, but sometimes angular, interstratified with sand, loam, and clay, exactly resembling the boulder-clays of Europe. These beds are generally quite horizontal, but are sometimes irregularly disturbed, as if tilted up by the stranding of an iceberg. In the shingle-clays” (the italics are mine), “which sometimes thin out in a distance of fifty or sixty yards from three to four feet to a few inches, I observed the remains of some exuviœ and bivalve shells, but so rotten that it was not only impossible to remove them, but even to ascertain the species; although I believed one of them to resemble the Venus intermedia of our seas.”
[Footnote] He further says:—“During a careful examination of the boulders forming these deposits, I was not able to detect any eruptive or volcanic rocks or débris of the tertiary deposits at the base of the latter, but only the different sandstones, slates, flagstones, pebble beds, and conglomerates which form the Southern Alps; whilst the rivers flowing through these zones now bring down a great quantity of volcanic detritus, from which we may conclude” (the italics again are mine) "that when these deposits of the glacial period were formed, the volcanic mountains (never more than 5000 feet, and generally 3000 to 3550 feet high) were lying below the level of the sea.”
But, singular and contradictory as this may appear, it would seem that Dr. Haast's recent repudiation of any elevation of the land in pleistocene times is not new, as may be inferred from the following passage, which occurs at page 22 of the report in question:—“During the greatest depression of the island in the post-tertiary era, there was doubtless a narrow arm of the sea, which ran along the western foot of Banks Peninsula, and of which we have ample evidence in raised beaches near it.” But the doctor limits the extreme height of these raised beaches to twenty feet above sea level. Now, although the utter discrepancy between the statements contained in the last quoted paragraph and those which occur in the passages which profess to give the “ causes” of the alleged glaciation would almost justify us in treating the whole of Dr. Haast's propositions as untenable, I think it as well to show, partly by reference to his own writings on other occasions, and partly by independent facts, how utterly unfounded it is under any system of interpretation which can be adopted. In 1865, the year after the date of the report from which I have already quoted, Dr. Haast reported to the Provincial Government of Canterbury on the structure of the Timaru district, with special reference to the probability of obtaining a supply of water in that locality by means of artesian wells. In this report he says:—
“The town of Timaru is situated on the eastern end of a dolerite plateau, which stretches from Mount Horrible, * * for ten miles to the sea, with a breadth of about six miles, between the northern bank of Pig-hunting Creek to the south, and the Washdyke Creek to the north.
“The existence of this dolerite sheet is the cause of the configuration of the Timaru roadstead, and of the preservation of the loose pleistocene strata lying upon the volcanic rocks, which otherwise, like similar strata to the north and south of Timaru, would probably have been destroyed by the great
glacier rivers in later pleistocene times. We must not, however, lose sight of the fact that as apparently none of those coming from the central chain reached the sea in this district, another favourable circumstance was added for the preservation of the estuary and fluviatile deposits, lying upon the dolerite, as well as of the loose young tertiary strata immediately below it.
“This dolerite plateau begins on the summit of Mount Horrible, the slopes of which, towards the Pareora and its northern tributary, are very steep and precipitous. The flat summit, consisting of dolerite identical with that of Harper's Hills in the Malvern Hills, forms vertical escarpments for about 100 to 150 feet, from the numerous fissures of which a fine vegetation grows, giving additional beauty to the picturesque scenery. A deep and straight valley runs here, as in the Malvern Hills, west of this great escarpment, suggesting at once that these dolerites deposited on the bottom of the sea were ejected by a longitudinal fault or fissure in the tertiary strata by which the valley is bounded on both sides. This valley, at the junction with the Pareora, is, according to barometrical measurement, 312 feet above the level of the sea, whilst the highest summit of Mount Horrible reaches to an altitude of 1138 feet.
“The capping of dolerite forms generally a horizontal sheet on that summit, although at some localities a dip towards east of as much as ten degrees at the edge of the escarpment may be observed.
“In travelling eastwards, after half-a-mile, the horizontal line of the dolerite changes, and the mountain begins to have a small slope, which is greatest above Mr. King's shepherd's hut, the foot of Mount Horrible being in fact situated here. This shepherd's hut, distant about seven miles from Timaru, lies 686 feet above the level of the sea.”
“Here at this shepherd's hut begins, properly speaking, the dolerite plateau, overlaid by silt, sloping at an almost uniform angle to the sea, and showing dolerite rocks in some gullies only, which have their beginning either in the eastern slopes of Mount Horrible, or even on the plateau itself for the surface drainage of the ground; but notwithstanding their local origin, the latter have been able not only to denude the loose silt deposits near the surface, but also to cut through the dolerite sheet into the looser tertiary strata beneath. This occurrence gave me an opportunity to convince myself that, as far as I was able to judge, only one large sheet was spread on that plateau, which with a slight gradual slope dipped towards east, whilst it had a nearly horizontal extent towards north and south, the fall being, as it seems, very slightly towards both directions. The fall for the last seven miles being only about 90 feet in the mile, or one foot in 58, the inclination is almost imperceptible.
“At the same time I became conscious of another fact, namely, that the dolerite stream as it advances towards east thins out so as to be, in some
places in the cliffs of Timaru, only four feet thick, but still exhibiting well, as I shall show in the sequel, the peculiar nature of these beds. This regularity is very striking and is of the highest importance, as it shows us, that since the deposition and cooling of that dolerite sheet, no disturbance, except a gradual slow upheaval of the country, has taken place, although other proofs are not wanting to demonstrate clearly that minor changes have occurred, and that the present configuration of the surface, near and in Timaru, is not at all in accordance with that which the dolerite below presents. There is no doubt that most of the many spurs which intersect the Timaru plateau in all directions, although all leading towards the sea, have been formed by the present surface drainage since the last silt covering was deposited.”
“I shall now proceed to give some details concerning the nature of the cliffs which form the Timaru roadstead, as they will assist in following the deductions at the end of this report, based upon the results obtained during this survey.
“The cliffs south of the landing place consist entirely of silt, forming banks often 50 to 60 feet high; but as, besides the occurrence of the dolerite in Saltwater Creek (Otipua) and Pig-hunting Creek, near the sea, the Patiti Reef shows these loose banks have been protected by the dolerites, which form here reefs in the sea, and which have broken, and are still breaking, the force of the waves and currents. After having passed the landing place, where I had an opportunity of examining the silt in the new cutting, giving a vertical section of about 25 feet, we reach the first bed of rocks.”
“The rock, for a thickness of about 10 to 12 feet, is here visible, and consists of large blocks, being irregularly joined, which has been without doubt the effect of cooling. These joints are filled with silt, often hardened and ferruginous, as if it had been deposited during the cooling of the rock, so that the heat had been sufficient to produce some change in it.”
“Advancing towards the north we pass to the next cliff, which consists entirely of silt, being at its northern end near the lagoon about 30 feet high. No fossils of any kind rewarded my search; and only in one locality the uniformity of this deposit was broken by the occurrence of a layer of white fine silt of about a foot in thickness, 12 feet above the sea level, interstratified with the yellow coarse silt, and having somewhat the appearance of glacier mud, being almost impalpable.”
At “Pig-hunting Creek * * the dolerites are only confined to its northern bank until it approaches the slopes of Mount Horrible, where again the rocks are exposed on both banks. Following the dolerite sheet of Timaru to the summit of Mount Horrible, we at once observe that it becomes thicker the more we advance towards that mountain, and, as the beautiful vertical precipice at its western termination shows, is here of a thickness of
more than 100 feet. Descending that mountain in a westerly direction, which, with horses, is rather a difficult task, we find below the dolerite the same burnt tufaceous beds as in the Harper Hills and the beach at Timaru; but afterwards for 300 feet no indication whatever of the nature of the strata is to be met with, till, at an altitude of 650 feet, another dolerite stream makes its appearance, which is of a more compact character than the uppermost or Timaru sheet.
“This stream overlies beds of a calcareous or marly nature, identical with those of the Curiosity Shop of the Rakaia, and of a middle tertiary age.”
“In summing up (he says) it will be palpable that no link in the evidence before us is wanting to come to a conclusion.
In the middle tertiary epoch, extensive strata of calcareous or argillaceous beds were deposited in this locality on a deep sea bottom * having an almost uniform slope towards the east.
Some of these beds, by their lithological character, are impermeable to water, being at the same time interstratified with permeable strata.
Submarine eruptions of dolerite took place, which, spreading over the sea bottom, covered the first named tertiary strata, protecting them at the same time from denudation.
Between these eruptions subsequent tertiary beds were also deposited, which, by repeated eruptions of dolerite, were also preserved.
Some of these younger beds present us with the same characteristics as described in No. 2.
The dolerite sheet on the summit of Mount Horrible” (which he states to be now 1138 feet above sea level), “which can be followed from there to the sea was the last deposited on the sea bottom. *
This sheet, by flowing towards east, where it terminates, becomes gradually smaller and thinner.
Since the deposition of this latter sheet, only minor changes took place, of which several old river channels now covered by silt, and as shown by the wells in Timaru, are witness.” (It will be observed that Dr. Haast treats an elevation of a deep sea bottom to the height of 1138 feet at least above sea level as a “minor change” only.)
That occurrence at the same time proves the oscillation of the ground, but the upward motion was predominant.
Finally, no signs of any disturbance, since the deposition and rise above the sea of the different levels alluded to, have been observed; so that by boring or sinking they will be found in their natural position.”
[Footnote] * The italics are mine.
[Footnote] * The italics are mine.
I have been obliged to extract somewhat at length from this paper, but it will be observed that the whole extract bears materially upon the questions at issue. If I read it rightly, the following conclusions appear to be fairly deducible from his language:—
It being stated that the upper capping of dolerite on Mount Horrible is 1138 feet above sea level, and that it was deposited upon a sea bottom composed of “younger pliocene strata,” it is evident that the rise in the land at this point, since this dolerite sheet was deposited, must have exceeded 1138 feet.
That looking to the alleged steepness of this dolerite sheet below the summit of Mount Horrible, and to the fact that the entire surface must have continued for a very long period as bare rock, exposed to the full swing of the Pacific Ocean, the conditions it offered were most unfavourable to its colonization by a marine fauna, except such as could resist the impact of the Pacific waves, and that, therefore, it is in no degree surprising that the “silt” which is described by Dr. Haast as covering this sheet in diminishing thickness from the foot of Mount Horrible to the present sea cliffs should not contain ordinary littoral remains.
That as the “silt” which covers this dolerite sheet, and which is spoken of by Dr. Haast as of pleistocene age, is found to have filled up all the hollows and depressions in it (as seen especially in the cliffs near the present sea shore), often to a depth exceeding fifty feet, and to extend back in diminishing thickness to the foot of Mount Horrible, this silt, as well as that on Banks Peninsula, which Dr. Haast calls “a slope deposit,” must be considered as having been deposited in standing water, notwithstanding the alleged absence of shells. It must be borne in mind that the mere absence of fossils is not sufficient to prove the purely terrestrial origin of such a deposit. The physical evidence must not be ignored, and when that evidence is clearly irreconcilable with any supposition other than that the deposit in question took place below the surface of standing water, the negative evidence afforded by the absence of traces of aqueous life, even in situations otherwise favourable to its existence and preservation, must be rejected.
The silt spoken of by Dr. Haast as occurring at Timaru and at Lyttelton presents, in both situations, distinct traces of stratification. At Lyttelton it attains, in many places, a thickness of upwards of 100 feet close to the level of the waters of the harbour, the bed of which is composed of precisely the same material. At the immediate shore line this silt exhibits, wherever it has been exposed to wave action, nearly perpendicular cliffs, resting on exposed lava beds; that portion of the silt which formerly completed the slope from the top of the cliff to the bed of the harbour having been removed by the waves. In sheltered situations the slope is still continuous, but the upraised portions show
no signs of imbedded shells. Indeed, Lyttelton harbour is singularly destitute of marine shells, except such as live in rocky situations, the silt in the harbour consisting of mud so soft that a wooden rod will sink many feet into it by its own weight.
It is remarkable, moreover, that in the Timaru beds, at the height of 650 feet above sea level, Dr. Haast observed a lower dolerite sheet underlying the above mentioned younger pliocene beds, and covering fossiliferous beds of lower miocene age; and equally remarkable that a prolongation of the gradient at which these lower fossil beds rise from sea level at Timaru would, at the same distance from the sea shore as certain fossils beds which are exposed at the Rakaia, carry them to about the same altitude above that level. These Rakaia beds are also of lower miocene age, and it may, therefore, be assumed that the beds covered by the lower dolerite sheet must have been above sea level during a greater part of the interval between that epoch and the occurrence of some depression during which the newer pliocene beds which overlie this lower dolerite sheet were deposited. I have reason, however, for believing that the beds which Dr. Haast has called “newer pliocene” are in reality of miocene age, and if this be the case, then my own views are further strengthened, as this fact would indicate clearly the absence of any pliocene beds in the district in question. I might quote, from many other papers of Dr. Haast's, statements irreconcilable with the views contained in his report of 1864, but I prefer proceeding to the consideration of independent facts bearing upon this part of the subject.
The accuracy of Dr. Haast's statement, “that the greatest height to which raised beaches occur on the eastern side of the Province of Canterbury does not exceed twenty feet,” is impugned by Captain Hutton, who informs us of the existence of raised beaches, examined by himself, on the eastern side of the island, not far to the north of the coast line of the Canterbury plains, extending to upwards of 300 feet above the present sea level; whilst he also gives reasons for believing that deposits which occur upwards of 1000 feet above it are also of recent marine origin. The former fact alone, however, would be sufficient to dispose of Dr. Haast's assertions, and the mere negative evidence afforded by the non-discovery of littoral shells amongst the materials of the Canterbury plains cannot outweigh them for a moment. Nor can I conceive that even Dr. Haast himself would venture to assert that his examination of the Canterbury plains—the materials of which below the surface are only exposed in the courses of the great rivers—has been sufficiently exhaustive to preclude the possibility of the existence of shell deposits in any part of them. I may urge, moreover, that the discovery of beds of sea shells amongst such materials as those which compose the major part of the plains—exposed as they must have been, if distributed by marine agency, during the
period when the area which they now cover was “a broad arm or channel of the sea” to the full swing of the Pacific waves—would be very singular, for Dr. Haast tells us that these waves were, at that time, sufficiently powerful completely to undermine and destroy tertiary strata bounding the area in question, and extending from Timaru to Double Corner.
Further, these gravels have been subjected for countless ages to the action of rain water percolating through them, which would, in all probability, have removed any traces of comminuted shells, even had the quantity originally been large. At the present time shells are rarely found upon any part of the Canterbury coast line which is exposed to the surf, and but few are found, and those only of comparatively fragile kinds, even within the area protected from its action by Banks Peninsula. It must further be noted, too, that the materials of which a large portion of the surface deposits of these plains is composed are such as would, in the lapse of geological times, be converted into very coarse sandstones and conglomerates, formations in which the preservation of shell deposits is but little looked for.
But, leaving this matter, I now propose to deal with the probability of the alleged glaciation of New Zealand, judging of such probability from the direct “causes” which Dr. Haast has assigned for it. It will have been observed that these so-called “causes” are, in effect, summed up by the learned doctor in two or three point-blank assertions, unsupported either by argument or evidence; whilst not a tittle of satisfactory explanation is vouchsafed as to the “causes” which subsequently led to its disappearance.
We are told that the South Island was repeatedly submerged during the tertiary period; and that, upon its final re-emergence, snow began at once to accumulate, in enormous quantities, upon the surface, further elevation leading to the formation of large glaciers, which at once began to eat back, I presume, into the plateau-like range of mountains. And the only “causes” actually assigned for the general glaciation which is alleged to have at once supervened, and to have continued for the large but indefinite portion of time occupied in the tremendous upheaval referred to—a glaciation, moreover, which is characterized by the doctor as being similar to that of Greenland and of the antarctic lands, is “the insular and peculiar position of New Zealand, its principal range or back-bone running from south-west to north-east, thus lying at a right angle to the two prevailing air currents, the equatorial north-west, and the polar south-east, both bringing moisture with them.”
Dr. Haast gives us no reasons, however, for supposing that the insular or other position of the islands has altered since the times referred to, nor does he suggest any ground, deducible from known physical reasons, why the glaciation he mentions, if it ever existed at all, should not still exist. The winds which then blew are, even according to Dr. Haast, the same as the
prevailing winds of the present day. There is no reason for believing that the moisture they then brought with them was greater than it is now. The country is still high enough, according to Dr. Haast, to produce all the effects assigned to the action of these winds in former times, for in the paragraph numbered 3 he says, in continuation of the passage last above quoted, that “the névés would soon have attained an enormous extent, and would have considerably lowered the line of perpetual snow, even had the land not been raised to a higher elevation than at present” (a circumstance which, by the way, he utterly repudiates in his recent presidential address), and, he adds, “the consequence would have been that glaciers of much larger extent would have descended down the natural outlets.” Now, assuming that the “causes” mentioned by Dr. Haast would have been sufficient to bring about the suggested glaciation, it is certainly inconceivable, seeing that the same “causes” are still in active operation, why the ice sheet should have melted away.
But Dr. Haast is utterly in error as to the direction of one of the winds which prevail on the coasts of the South Island, and which he describes as the “polar south-east wind.” Such a wind, as a surface wind, is entirely unknown in these latitudes, either to physical geographers or to the present inhabitants of the island, and, indeed, its existence is a pure and unwarranted assumption. The prevalent winds of the South Island are the general westerly winds which are laid down on the wind charts of physical geographers as occurring between the thirtieth and sixtieth parallels of south latitude, and are, in effect, the same as the prevalent westerly winds which impinge on the western coast of South America.
Mr. Darwin, speaking of the effect produced by these winds, tells us that “the windy, humid, and equable climate of Terra del Fuego extends with only a small increase of heat for many degrees along the coast of that continent. The forests for 600 miles northward of Cape Horn have a very similar aspect. As a proof of the equable climate, even for 300 or 400 miles still further northward, I may mention (he says) that in Chiloe (corresponding in latitude with the northern parts of Spain) the peach seldom produces fruit, whilst strawberries and apples thrive to perfection. Even the crops of barley and wheat are often brought into the houses to be dried and ripened. At Valdivia (in the same latitude of 40° with Madrid) grapes and figs ripen, but are not common; olives seldom ripen even partially, and oranges not at all. These fruits, in corresponding latitudes in Europe, are known to succeed to perfection. Although the humid and equable climate of Chiloe, and of the coast northward and southward of it, is so unfavourable to our-fruits, yet the native forests, from latitude 45° to 38°, almost rival in luxuriance those of glowing intertropical regions. Stately trees of many kinds, with smooth and highly
coloured barks, are loaded by parasitical monocotyledonous plants; large and elegant ferns are numerous, and arborescent grasses entwine the trees into one entangled mass to the height of thirty or forty feet above the ground. An equable climate, evidently due to the large area of sea compared with the land, seems to extend over the greater part of the southern hemisphere, and, as a consequence, the vegetation partakes of a semitropical character.”
It will be seen that the learned and careful observer from whom I have just quoted, does not even hint at the probability of glaciation being produced, in the district which he describes, by the action of the winds in question, although, as will have been remarked in connection with a former extract from the same work, his attention was specially directed to the climate of the South Pacific lands. It will also be noted by those who are acquainted with the indigenous vegetation of the western coast of the South Island, how closely it resembles in character the vegetation of that part of the tract referred to by Mr. Darwin, which lies between the fortieth and forty-fifth parallels, although the drier climate which the former enjoys, owing to well-known causes, enables some of the fruits he mentions to be ripened in a much lower latitude in New Zealand than is possible on the west coast of South America.
I propose, in the sequel, to add some further remarks in connection with this branch of my argument, although I think I have already sufficiently shown that the only “causes” assigned by Dr. Haast for the alleged glaciation, even assuming that he had not committed a grave error in his statement of facts, would be utterly unequal to the occasion. But let us examine into the probability of the occurrence of the alleged glaciation, judging of such probability from a consideration of matters which are not even hinted at by Dr. Haast, although, as will be seen, they must have a very important bearing, not only upon the learned doctor's propositions, but also upon all questions affecting the existing physical conditions of these islands.
In the first place, their total submergence during the tertiary epoch—and I speak of the whole of the islands advisedly, because I cannot conceive for a moment that the South Island could have sunk 13,000 feet below its present summit level without being accompanied in its dip by the North and Stewart Islands—must have been attended with the complete extinction of all the then existing forms of terrestrial life, unless, par hazard, some New Zealand antitype of Noah had amply provided for the emergency. But, as if to prevent any beneficial result from such provident foresight, as well as all other reasonable prospect of re-peopling the islands, no sooner do they begin to emerge again after their long plunge, than the doctor proceeds to invest them, for an indefinite period, with an uniform pall of ice and snow extending to the very water's edge!
Having inflicted these terrible blows, he ought certainly to have helped us
to some explanation of the manner in which they ultimately shook off their dreary clothing, and assumed, in lieu thereof, their present rich and varied garb, and how they became inhabited by the moa and the kiwi, and by other creatures whose powers of crossing the 1200 miles of ocean which intervene between New Zealand and the nearest continental land, even if they had originated there, are of the very weakest. Perhaps, indeed, the learned doctor believes that our present fauna was evolved “in those pleistocene times” out of the moral consciousness of some mollusc or crustacean resting and pondering, after the long winter, on the shores of the pleistocene sea; or, perhaps, all this dreadful submergence and glaciation may have been confined to the area of the present Province of Canterbury, as a fitting preparation (in the eyes of Dr. Haast) for the formation of the celebrated Canterbury plains, leaving the rest of New Zealand to pursue the even tenour of ordinary geological ways.
But I will ask Dr. Haast, whether he has at all considered the effects which the grinding action of such an ice sheet as that in which he has chosen to envelope New Zealand “in those pleistocene times” would produce upon its surface? Has he speculated, beyond the conjectured “desolate aspect,” upon the appearances which the surface would present when, in the fullness of time, the ice sheet had been removed? Can he, for example, point to the existence, in any part of New Zealand, of boulder clays of the class constituting the upper glacial series, as exhibited in the north of England and in many parts of Scotland, and which Mr. Wood has given good reasons for believing to be composed of matter formed underneath a great ice sheet analogous to that of Greenland, and gradually extruded upon the floor of the sea? So far as I can judge, in no part of the South Island, at all events north of the Waitaki River, can the morainic matter that occupies the great mountain valleys be referred to the action of such an ice sheet. The terminal moraines, even when of largest dimensions, are restricted to these valleys, in some instances no doubt extending to short distances beyond them, but in most cases confined to their upper reaches.
Let us see how Mr. Geikie sums up the work produced by the ice sheet which enveloped the Highlands of Scotland in that part of the “great ice age” during which the Lowlands were submerged. At page 252 of the work already quoted from, he says:—“When the great ice sheet was beginning to deposit the boulder clay which is now met with in the maritime districts, the higher hills of the central Lowlands stood above the level of the mer de glâce, like islands in a frozen ocean. At the same time the mountain ridges of the Highlands and the bold hills of the southern uplands rose up so as to separate the ice sheet into a series of gigantic local glaciers, which, however, still coalesced to form one mighty stream upon the Lowlands. Frost shivered the rocks and loosened out great blocks, which eventually toppled down upon the ice below,
and along with heaps of angular rubbish were slowly carried away. Sometimes the stones and boulders fell into crevasses, or between the ice and the rock of the mountain slopes, and so got ground and polished on one or more sides, but they always travelled farther and farther off from their parent mountains. The tops of the Lowland hills, peering above the ice, caught some of the wanderers as they drifted past; but many were borne out to the terminal front of the ice and dropped into the sea, where they mingled with the scratched stones that were being pushed out from underneath the glaciers. As the ice continued to melt, erratic and angular débris was stranded at ever-decreasing heights upon the mountain slopes and hill sides, and at last the ice drew back from the sea and the glaciers then dropped their rubbish upon the land. Great streams of water escaping from the melting ice swept the morainic matter down the valleys, and angular stones and rubbish, as they were pushed along, became rounded by attrition and arranged by the rivers in great flats of gravel and sand. Thus, ever as the glaciers withdrew, the angular débris that gathered in front of them was ploughed down and distributed over the bottoms of the valleys by the swollen rivers, the perched blocks at great elevation on the sides of the valleys, and upon the slopes of the Lowland hills, still remaining to indicate the heights formerly reached by the glaciers. There being no great river valleys draining from the mountain regions in the low grounds of Lewis and Caithness, the absence of glacial deposits from such districts is easily accounted for. To what extent the ice was eventually reduced we have no means of ascertaining, neither do we know much of the climatal condition which at this period obtained in Scotland. All that we can safely assert is, that the ice disappeared entirely from all the low lands, and drew back into the deeper mountain valleys. Of the plants and animals which at this time may have clothed and peopled the land, we know-next to nothing. I have here and there, in the gravel and sand beds, detected some vegetable matter, but in too decomposed a state to enable me to say what it was. In one section, however, near Carhum, on the Tweed, I obtained from a bed of sand in the series numerous remains of water-rats and frogs. It would be hard to believe that these were the sole denizens of the land; as yet, however, they are all we have got to show. After such conditions had lasted for a longer or shorter period, the land gradually sank into the sea. As it slowly went down the waves and currents ploughed up and re-distributed much of the old glacial accumulations and river deposits. Broad terraces of gravel and sand were cut into, and their materials winnowed and re-arranged. Here and there, also, ridges of gravel and cones of sand were heaped up in places where no sand and gravel existed before, the sea using up for the purpose the till and morainic rubbish.”
If such an ice sheet as Dr. Haast has conjured up had ever occupied the
surface of the South Island since it attained its present elevation above sea level, or indeed since miocene times, the utter absence of such evidences of its existence as those which occur in Scotland, resulting from similar phenomena, is most unaccountable. But whilst I utterly deny Dr. Haast's propositions, I at once admit that the former existence of glaciers of great extent is a necessary assumption in any attempt to account for the phenomena presented to us in the localities mentioned in my former paper.
I would further ask Dr. Haast, how it is that he has not brought forward any evidence derived from the organic world of “those pleistocene times,” in order to establish his propositions? Surely, if the views he has propounded be at all based upon fact, he would have been in a position to go further than the barest assertions in support of them! Do any of the pleistocene deposits which he has examined afford indications of such a climate as that which must have accompanied the alleged glaciated condition of these islands? What can he point to in the features of the existing organic life of these islands, from which we can trace the former existence of such a glaciation?
The careful comparisons which have already been instituted between the existing Mollusca of our seas, and fossil species extending in age from recent up to upper eocene times, has failed to indicate the occurrence of any such glaciation. The number of pleistocene fossils examined was very considerable, and a large proportion of them was obtained in the South Island, in localities in which evidences of such a glaciation would have been found in abundance, if the glaciation itself had ever existed.
Again, how is it, if the alleged glaciation had attained the dimensions assigned to it by Dr. Haast, or indeed anything approaching such dimensions, or even dimensions equal to those of the greater glacier period of the Swiss Alps, that we do not find evidences of its extension at points beyond those to which that extension is limited in the maps appended to his report? If, as he asserts, the area of the Canterbury plains maintained its present position relatively to sea level, and its present surface conditions, throughout the period of the asserted glaciation, the absence of all evidence of the kind mentioned by Morlot and others in proof of the extension of the Swiss glaciers during the greater glacier period of the European Alps, is most remarkable. During this latter period the great valley of Switzerland was filled with ice, as is attested by the presence of unmistakable remains on the Jura, whilst, on the southern side of the Alps, ample evidence exists, in the form of moraines of truly gigantic dimensions, that contemporary glaciers invaded the plains of the Po. “Although these large glaciers had retreated for a time” (I quote from Sir Charles Lyell) “they advanced again, but on a smaller scale, though still vastly exceeding in size the largest Swiss glaciers of our day.” Careful observers like Professor Heer, who is cited by Sir Charles Lyell in reference
to the climate of Switzerland, during the interval between these two glacier periods, do not content themselves with bare assertions on points of scientific importance, and the learned Professor took care to point out that the character of the fossil fauna and flora from the drift of the intervening period was such as to support the a priori conclusion deducible from a comparison between the greater and the less extensive glaciation, that the climate was milder during that intervening period than that of the periods which had preceded and succeeded it.
But Dr. Haast adduces no evidences of the several kinds I have pointed out in support of his assertions, and simply, as I believe, because they do not exist. No morainic accumulations are to be found on the Canterbury plains, except at very short distances below the mouths of the greater valleys. No boulder clays are to be found of the kind which would result from the action of an ice sheet. Nowhere on Banks Peninsula are to be found the smallest traces of glaciation. Nothing in the character of the pleistocene fauna or flora indicates it. In fact, I may safely challenge Dr. Haast to produce the slightest evidence, calculated to satisfy scientific men, in support of his assertions. Tyndall tells us that “the scientific mind is fond of verification, and never neglects it where it is possible.” Dr. Haast prefers broad assumption and bare assertion. I have no hesitation, however, in utterly rejecting his propositions respecting the alleged glaciation, not only because they are rash and unsupported, but also because they conflict with all the facts which are thrust upon us (so to speak) by an examination of the existing physical features of these islands.
I might here have closed this paper, but I have thought it desirable not to do so without referring to some remarks made by Dr. Hector during the short discussion upon my paper of last year, and I do this more especially because those which I am about to make in reply have also a strict bearing upon the general subject under discussion. On that occasion Dr. Hector referred to a letter written by himself to Dr. Hooker, in 1864 (which is quoted approvingly by Sir Charles Lyell, at page 241 of the first volume of the Principles of Geology, tenth edition), in which, if the quotation of Sir Charles be correct, Dr. Hector appears to have stated in effect as follows:—“Dr. Hector has remarked that the north-west winds, when they blow for several days in succession from Australia to the South Island of New Zealand, are so hot and dry as to cause great floods by the sudden melting of the snow on the Northern Alps of that island. He observes that if Australia were submerged, or if at some former period the sea covered a large portion of the space now occupied by that continent, the New Zealand glaciers, which are now of considerable size, would have been more voluminous.”
Now, although Dr. Haast has frequently quoted Dr. Hector in a manner
which might lead to the assumption that the latter agreed, in the main, with the glaciation theory already discussed in this paper, it is clear that the language of the letter just cited does not even countenance Dr. Haast's extravagant propositions. But whilst, as already stated, I fully admit a former extension of the glacier system of the South Island mountains, I am unable, partly for the reasons already urged and partly for those to which I am about to refer, to accept the views set forth in Dr. Hector's letter as sufficient to account for it.
In an earlier part of this paper I pointed out that the principal winds which impinge upon the coast of New Zealand are the well-known westerly winds which prevail between the thirtieth and sixtieth parallels of south latitude. Satisfactory reasons are given by physical geographers why these winds should be drier than the corresponding winds of the northern hemisphere, but I think I shall be able to show that, although the climatal condition of the western coast of New Zealand is, in great measure, due to the action of these winds, the winds themselves are in no degree dependent upon the climatal condition of Australia for that in which they arrive on our coasts.
It must be remembered that when these winds become surface currents they are cool winds, the warmth they acquire, and which enables them to pick up moisture, being due partly to condensation and partly to friction, while they become charged with moisture during their passage over the waters by which Australia is separated from New Zealand. In the next place it must be borne in mind, that the distance between these islands and the eastern coast of Australia is not less than 1200 miles; and, lastly, that the whole of the heat producing area of Australia, if I may use such an expression, lies to the north of the thirtieth parallel, and therefore within the south-east trade region. Moreover, all physical geographers class the climate of that part of Australia which lies to the south of the thirtieth parallel as amongst the temperate climates of the globe.
So far, then, from our north-west winds coming to us in a heated condition, in consequence of having passed over Australia, the winds which pass over that part of it which can in any degree be treated as lying to the north-west of us, blow towards a directly opposite quarter. Indeed, it is in great measure owing to this that the island of Timor, the eastern end of Java, and the southern peninsula of Celebes present the parched appearance particularly mentioned by Mr. Wallace in his work on the Malay Archipelago; whilst Mr. Maury and other writers on physical geography explain, that the chief reason why Australia itself is so dry a country is that its eastern coast line is stretched out in the direction of the south-east trade wind, which therefore only fringe its shores with moisture. Dr. Hector appears, when considering the source of
the moisture of our north-west winds, to have overlooked the fact, that the great equatorial current of the South Pacific, after flowing in a broad stream down the eastern coasts of Australia and Tasmania, curves to the northward, in which direction it flows along, but at some distance from the western coast of New Zealand still possessing a temperature of 68° of Fahrenheit. It must not be forgotten, moreover, that the northern point of New Zealand lies within 600 miles of the tropic of Capricorn, and within 300 miles of the southern belt of calms, whilst the climate of the whole (as the following extract from a publication on New Zealand, to which Dr. Hector contributed this portion of its matter, will show) is generally milder than that of corresponding latitudes in Europe:—
“The changes of weather and temperature [in New Zealand] are very sudden; calms and gales, rain and sunshine, heat and cold often alternating so frequently and suddenly as to defy previous calculation, so that there cannot be said to be any uniformly wet or dry season in the year. But, although these changes are sudden and frequent, they are confined within very narrow limits, the extreme of daily temperature only varying throughout the year by an average of twenty degrees, whilst in Europe (at Rome and at other places of corresponding latitude with New Zealand) the same variation amounts to or exceeds thirty degrees. In respect to temperature, New Zealand may be compared either with England or with Italy, but London is seven degrees colder than the North, and four degrees colder than the South Island of New Zealand, and is less moist.
“The mean annual temperature of the North Island is 57 degrees, and of the South Island 52 degrees, that of London and New York being 51 degrees, whilst at Edinburgh it is only 47 degrees, the heat in summer being tempered by the almost continual breezes, and the winter cold being not nearly so severe as at any of the above mentioned places, except in the uplands and extreme south.
“The mean temperature of the different seasons for the whole colony is, in spring, 55 degrees; in summer, 63 degrees; in autumn, 57 degrees; and in winter, 48 degrees; January and February, corresponding to July and August in New Zealand, and July and August, corresponding to January and February in England, the two coldest, except in Nelson and Wellington, at which places the mean temperature is lowest in June and July.
“At Taranaki the climate is remarkably equable, as snow never falls near the coast. At Wellington it is very variable, and subject to frequent gusts of wind from the hills which surround the harbour.
“Nelson enjoys a sheltered position and a clear sky. In Canterbury the seasons are more distinctly marked, the frost in winter being occasionally severe (although it never freezes all day near the coast) and the heat in
summer often very great. The winter in Otago is decidedly colder, and severe frosts with deep snow on the uplands are common in the winter.
“Stewart Island is subject to violent winds and frequent fogs.
“Strong winds are prevalent thoughout the colony, and particularly in the straits.
“Rain falls frequently, but seldom in such excessive quantity or for periods of so great length as in Australia, the heaviest rain seldom exceeds two days' duration, excepting on the West Coast, whilst it is rare for a fortnight to elapse without a shower. The rainfall for the year 1871 was 54–1/2 inches, the average rainfall in England being.”
In conclusion, I repeat that, for the reasons shortly given in this paper, I have no hesitation in believing Dr. Haast's glacial hypothesis to be utterly untenable, whilst he has called upon his readers to accept it without adducing in support of it any of those evidences which alone should satisfy the judicious enquirer, and I cannot help expressing my regret that he should continue to maintain those views dogmatically, in opposition to that simpler explanation of the phenomena to be elucidated, which the observance of sound principles of geological investigation might have led him to.
Note.—Since the foregoing paper was written our President has stated, in the address with which he favoured us at the opening of this year's session, that the north-west winds which impinge upon the west coast of the South Island derive their heat from the surface of Australia. This is a repetition of what I considered, for the reasons already shortly stated, to have been an error on the part of Dr. Hector; but, seeing that our President has also given his countenance to the same views, I think it now necessary to state, in somewhat further detail, the reasons which weigh with me in rejecting it.
All physical geographers agree as to the direction of the great air currents which result in the trade winds, and of those by which the place of that portion of the atmosphere which is engaged in the production of these winds is refilled. In the southern hemisphere the current which ultimately produces the south-east trade wind is an upper current flowing towards the north-west, in a sort of spiral or loxodromic curve, between the sixtieth and thirty-third parallels of south latitude. On reaching the latter, at the outer edge of what are termed the calms of Capricorn, it plunges, passing under the comparatively warmer currents (to which I will hereafter refer) and becoming a surface wind, blowing more directly towards the north-west until it reaches the equatorial belt of calms. After it has thus become a surface wind it is called the southeast trade wind. In like manner, the current which produces the north-east trade wind flows in a similar spiral or loxodromic curve, as an upper current, between the parallels of 60° and 30° of north latitude, at the latter of which it also plunges, passing through the warmer current to which I will shortly refer,
and becoming the north-east trade wind, blowing towards the south-west until it also reaches the equatorial belt of calms. This belt of calms is caused by the contact of these two currents. At this point both begin to ascend, and, becoming cooler by expansion in the upper region, a considerable proportion of the moisture which they have absorbed as trade winds is precipitated. According to Maury, each of these upward currents, after passing over the tropical region between the equatorial and solstitial belts of calms, again plunges at the latter, passing under the descending cold currents from the polar regions. Whilst thus plunging a further proportion of the moisture left in them is condensed, causing that peculiar cloudy character which distinguishes the districts between the limits of the solstitial calm belts. After this plunge they again become surface currents, flowing towards the poles in spiral or loxodromic curves, in order to replace the material of the upper polar currents above referred to, but in directly opposite directions, the north-east trade wind becoming a north-west wind to the south of the thirty-third parallel of south latitude, and the south-east trade becoming a south-west wind to the northward of the thirtieth parallel of north latitude. Those two return currents are then called the anti-trades.
Sir John Herschell, who differs in some respects from Maury, says:— “The trade winds occupy two belts on the earth's surface, on either side of the equator, which are limited on the equatorial side by a belt of calm air, the movement of which is upwards, and in which no prevailing tendency east or west is perceivable. On the polar they are limited by two belts of comparative calm, with uncertain and variable winds, which for our present purpose we may consider as nearly coincident with the tropics. Over the belt of equatorial calms, the north-east and south-east trades, reduced to meridional directions by the eastward frictional impulse of the earth's rotation (Basil Hall, Fragments of Voyages and Travels, 2nd series, 162) meet, and, to a certain small extent perhaps, commingle in their upward movement, which, however, can only be the case with those portions of air which actually attain the medial line or approach very near it; for, as the regions of calm extend to four or five degrees on either side of that line, the greater part by far of either indraught will rise on its own side, and must of necessity be turned over towards the pole of its own denomination, and return as an upper current by a track precisely the reverse of that of its arrival. On the other hand, over the region of tropical calms a portion of the descending air of the upper current, where it first strikes the earth, is dragged back into the tropical circulation, while the rest goes forward to form the anti-trades (or south-west and north-west winds) of the temperate and polar zones, which, as prevalent winds, with more or less frequent interruptions according to local circumstances, occupy both the extra-tropical regions.”
It will be observed, however, that although Sir John Herschell considers his own as the correct dynamical view of the course of the great air currents after their meeting at the equatorial belt of calms, he does not differ from Maury as to the general effects resulting from their meeting. It may be presumptuous in me to attempt to decide between two such authorities, but the climatal condition of the northern part of Australia induces me rather to lean to the views of Mr. Maury. Now, looking to the geographical position of Australia, the cause of its peculiarly dry climate will at once be seen, for its eastern coast, to the northward of the thirtieth parallel, is stretched put in the direction of the south-east trade wind, which only fringes its shores with moisture, whilst the whole of the continent to the north of the thirty-third parallel receives the dry upper polar current in the form of the south-east trade wind. To the south of that parallel the winds are the return, or anti-trades, deprived of a large proportion of the moisture they had absorbed in their passage over those parts of the waters of the North Pacific which lie to the windward of Australia, and restored to a comparatively warm condition by condensation. But they still retain a sufficient portion of moisture, increased moreover in their passage across Bass Strait, to make the climate of Tasmania temperate and agreeable.
Looking, further, at the geographical position of New Zealand in relation to Australia, and bearing in mind that the return current from the north-east trades, which forms the north-westerly winds of the southern part of our hemisphere, moves in the curves before indicated, it is impossible that any portion of the north-west winds which blow over the southern parts of Australia should reach New Zealand at all; I have little doubt, indeed, that they pass considerably to the southward of these islands, and that their most easterly margin would not be found further north than the Auckland Islands. Nor is it at all essential to invoke the heated condition of the surface of Australia to account for the warmth of the winds of the Canterbury plains. The degree of warmth is very much the same as, but perhaps a little greater than, that of the northwest winds of the southern parts of Australia, and becomes sensible in the manner explained by our President.
I quite agree with our President as to the chilling effect upon the person of these winds as they come off the sea, but it must be remembered nevertheless that, as anti-trades, they are considered to be warm winds by physical geographers (see Sir John Herschell's Physical Geography, page 268). I believe, moreover, that the winds in question, before they reach the plains, receive a large amount of additional heat from radiation, for these hot northwest winds are usually preceded by dry, cloudless, and calm weather on the eastern side of the mountains, and I know from experience how extremely sultry the air in the valleys becomes during such weather. It is, of course,
difficult to convey a clear idea of these views without the aid of diagrams, but an examination of the wind and ocean current charts of the southern hemisphere will, I think, show that they are consistent with received opinions. Our President also leads us to believe that he inclines to Dr. Haast's views as to the glaciation of these Islands in pleistocene times, which, however, he refers to cosmical causes in no degree hinted at by Dr. Haast in the paper I have criticised, and at the same time appears indisposed to acquiesce in the assumption of a greater elevation of these islands during pliocene times. But it appears to me that our learned President, in dealing with the latter question, has entirely overlooked the evidence afforded by the organic life of the group of islands curving round the eastern side of New Zealand, from Sunday Island in the north, by the Chatham group to the Antipodes, the specific identity of which with that of New Zealand, can, as I conceive, only be accounted for by assuming a former land connection between them, severed by a subsidence which took place since miocene times.