Glaciation in New Zealand — the first century of research

Quaternary Science Reviews, Vol. 4, pp. 189-214, 1985. Printed in Great Britain. All rights reserved.

GLACIATION

0277-3791/85 $0.00 + .50 Copyright © 1986 Pergamon Press Ltd.

IN NEW ZEALAND m THE FIRST CENTURY OF RESEARCH

Maxwell Gage

9a Anderson Street, Taradale, Hawkes Bay, New Zealand

The year 1965 is seen as the end of a prolonged pioneering stage in New Zealand Quaternary studies. Description of evidence of formerly extended glaciers began in 1861, and by 1965 about 138 relevant publications had appeared. The following factors and developments in particular influenced directions and progress: (1) initially, ongoing 19th century interest in the 'Glacial Controversy' and consequently in 'Ice Age' manifestations in the large, isolated, middle-latitude islands of New Zealand; (2) from 1864, vigorous gold-mining excavations in Quaternary morainic deposits; (3) throughout the period, domestic disputes about the extent of glacierisation, the number and dates of glacial events; (4) especially after 1917, consistent extension of sound stratigraphic terminology throughout New Zealand; (5) in 1944, recognition of evidence for temperature fluctuations in fossiliferous Late Tertiary/Pleistocene marine strata in North Island, with prospects for correlation with South Island glacial events; (6) after World War II, more overseas contacts and experience, giving confidence to those developing independent criteria for distinguishing and evaluating successive ice advances and non-glacial interludes; (7) also mainly since the War, facilities for aerial mapping, radiocarbon dating and palynology; (8) a new 1:250,000-scale mapping programme by the Geological Survey begun in 1957, which raised many nomenclatural questions. From 1957, internal glacial correlations and progress towards an essentially climate-stratigraphic classification culminated in Suggate's 1965 scheme, embodying a Holocene subdivision preceded by four Late Pleistocene glacial stages with non-glacial interludes and by an Early Pleistocene glaciation. Despite some correlation problems and questions as to the status of certain intervals, the scheme has been widely accepted and used. Recent work, however, suggests that the time for substantial revision is at hand.

INTRODUCTION For the past 20 years Q u a t e r n a r y workers in all fields in New Zealand have had available a more or less stable, essentially climate-stratigraphic time framework for the Late Pleistocene. The purpose of this review is to identify the events, provocations and circumstances which seem most significantly to have influenced directions and progress in glaciation studies from their beginnings in the early 1860s until what is regarded as the end of a long pioneering phase a century later, when the chronological scheme in current use was enunciated by R.P. Suggate (1965a). Authors and works referred to herein include, it is hoped, the most important contributions and should provide an adequate entr6e to the subject. Chief sources of information are listed later. The year 1965 is a convenient and logical cut-off point. Suggate's major publication in that year brought together his own and others' observations in the most critical areas of the 189

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northern half of the South Island, integrated with evidence of varying kinds for warm intervals between the ice advances, correlated locally and inter-regionally, ordered in terms of magnitude and systematically named for mapping purposes. Moreover, it declared the principles, assumptions and criteria that had been adopted in order to achieve consistency. Issued in the Bulletin series of the New Zealand Geological Survey, the work was accepted as authoritative and it serves as a fitting culmination of the exploratory (one might even say 'heroic') stage of glaciation study in New Zealand. A climate-stratigraphic framework had been developed, diffidently at first but with increasing confidence in its reliability. Though still largely relative in the time sense, such a chronology was very useful in branches of Quaternary science other than geological and outside the glaciated regions. The post-1965 period is rather a different story, worthy of a separate review at a later date. In addition to what has come up in connection with challenges to Suggate's interpretation of interglacial evidence and modified correlations, much new data has been gathered, new and improved methods of dating and assessing environments have been applied and a whole new generation of investigators has appeared on the scene. A number of refinements and amendments to the 1965 chronology and terminology have been needed and still more may be expected. Earlier apparent distinctness between Early and Late Pleistocene events and between Pliocene and Pleistocene are fading, and the time is at hand for a thorough overhaul which must involve discarding of some very familiar terms that have become confused through subdivision and revised correlation. Finally, it will be noted that studies of the minor glacier fluctuations (Holocene) that have occurred since the great retreat at the end of the Last (Otiran) Glaciation from about 12 ka BP are not covered in this review. New Zealand rocks of the earlier epochs have yielded no evidence for pre-Pliocene glaciations.

The Setting The New Zealand group of islands (population ca. 3 million) in total area slightly exceeds that of Great Britain. It is set in the South-west Pacific Ocean roughly between latitudes 34°S and 47°S nearly 1,800 km from the nearest landmass. Large glaciers still exist in the higher central and southern portions of the Southern Alps and in West Otago. Evidence abounds of their former extensions from mountain valleys out onto adjacent lowlands in many parts of the South Island, wherein the highest peak (Mount Cook) attains 3,764 m altitude and many summits exceed 3,000 m. In the North Island perennial ice is now confined to the summit of Ruapehu volcano (2,797 m) and traces of Quaternary glaciation elsewhere are very limited.

Early European Observers Voyages of scientific rather than purely geographical exploration visited New Zealand in the late 18th and.early 19th centuries. Remarkably soon after systematic colonisation by Europeans commenced (about 1840) the natural history of this latest addition to the British realm was being studied very competently. Spectacular moraines with associated vast alluvial plains and terraced lands in the south naturally attracted early attention, although few of the initial observers had had much prior experience of glacial phenomena in Europe. In any case, the setting of glacial features in New Zealand was rather different from that of

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the classical glaciation studies in the Northern Hemisphere, while to begin with the investigations were pursued in the remoteness of the far side of the world in sailing ship days. Hence they were not unduly tramelled by conservative thought in the Northern Hemisphere centres of learning. It was well into the 20th century before the relative isolation of New Zealand scientists effectively ended. Systematic geological exploration is deemed to have begun late in 1858 when Dr Ferdinand von Hochstetter left the Austrian frigate Novara, then on a globe-encircling voyage of scientific exploration, at Auckland to make a geological examination of a nearby coalfield. While in Auckland Hochstetter met Julius Haast, also recently arrived from Austria, and he arranged for Haast to accompany him on his N e w Z e a l a n d expeditions. In the mountainous interior of Nelson Province in the north-west of the South Island they reached the fringe of formerly glaciated areas. Then, leaving Haast to carry on with geological explorations for the Nelson Provincial Council,* Hochstetter departed for home towards the end of 1859. The full, definitive account of his New Zealand observations was published in Vienna in 1864 (see Fleming, 1959a) along with geological maps and a 'Synopsis of Formations'. These noted 'glacial drift' marking the 'New Zealand Glacier Period'. Meanwhile Haast had moved to Christchurch to become Provincial Geologist for Canterbury, and the Otago Provincial Council had appointed James Hector to a similar post at Dunedin. (More about the origins and careers of these men will be given later.) Both were soon describing signs of formerly extended glaciers in the central and southern parts of the South Island in locally published reports and articles, some of which later reappeared in condensed form in British journals (e.g. Haast, J., 1864; Hector, 1865).

The Literature The bulk of relevant work appeared in the following New Zealand publications:

Transactions of the New Zealand Institute (from 1933 the Royal Society of New Zealand); Reports of Geological Explorations by the original Geological Survey established under Hector in 1865; Bulletins of the present New Zealand Geological Survey (since 1906); New Zealand Journal of Science and Technology (1918-1957); and two of the serials that replaced the last: New Zealand Journal of Geology and Geophysics and New Zealand Journal of Botany. Review papers and relevant committee reports appeared from time to time in conference proceedings such as those of the Australasian (now Australian and New Zealand) Association for the Advancement of Science and of I N Q U A , and in overseas journals such as Geological Magazine and Quaternaria. Some are in early reports and books so rare as to be difficult to acquire now even in New Zealand. Some of these New Zealand publications are available in the older and larger scientific libraries of the United Kingdom and the eastern United States, but many are difficult to find outside London. Where N.Z. Geological Surveys Bulletins are available, one may easily trace all but a few of the important papers with the help of comprehensive bibliographies of New Zealand geology (Adkin and Collins, 1967, up to 1950; Warren et al., *The country was still sparsely populated. Local government of its widelyscattered settlementswas in the hands of a number of Provincial Councils responsible to a central legislature at first in Auckland, but transferred in 1865 to Wellington.

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1977, 1951-1969) and their companion subject-indexes (Jenkins, 1976, 1982). A further useful source is the list of references at the end of the Quaternary chapter in The Geology of New Zealand (Suggate, 1978) [1980]. The number of people in New Zealand at any one time actively engaged in Quaternary research would rarely have reached half a dozen in the review period; and yet a quick scanning of the bibliographies tallied 138 titles related to Quaternary studies up to the end of 1965. This, by the way, is out of a total of roughly 7,000 for the whole of earth science over the same period.

STIMULI AND PROVOCATIONS

The Glacial Controversy At the time when Hochstetter and Haast came to New Zealand the theory of an Ice Age having affected the Earth at a late stage in its geological history still encountered entrenched opposition in some quarters, but at least as regards the middle and higher latitudes in the Northern Hemisphere it was generally accepted. Its adherents were however divided into those who envisaged great extensions of glaciers from the mountains as well as land-based continental ice-sheets, and others including influential people like Roderick Murchison who preferred the 'drift theory' whereby till or boulder-clay was attributed to subaqueous deposition from floating ice. Which version best fitted the newly explored glaciated regions of the Southern Hemisphere? Haast had studied mineralogy and geology in the University of Rhine-Prussia before going to New Zealand but nothing suggests that he was especially interested in glacial action. Hochstetter, already a distinguished scientist and Professor of Mineralogy and Geology in Vienna, was born and educated ~n Southern Germany within 100 km from strongly glaciated terrain. Reputedly a 'drift' supporter, he would be aware of the glacial controversy and familiar with signs of glacial action. No doubt both men would be curious as to how the Ice Age affected these high-standing islands in the mid-southern latitudes of the Pacific Ocean. James Hector originated in glaciated surroundings in Scotland, and studied medicine and 'natural science' including geology at Edinburgh University, long a forum of debate about the Glacial Theory. Before coming to New Zealand Hector was engaged in exploring the glaciated Rocky Mountains of Canada. Haast's notable career as explorer, pioneer geologist and museum-builder is documented in a voluminous biography compiled by his son H.F. Haast (1948) who illustrates the development of his father's ideas by means of many extracts from correspondence and from publications and official reports, many of which are no longer readily accessible. From this work and from bibliographies it is clear that if Haast's interest in glacial matters had not been aroused already, it very soon was. In connection with the hypotheses of greatly expanded land-ice and the ability of glacier ice to degrade basins in hard rock he was in contact from 1862 onwards with L. Agassiz, J.D. Hooker, R. Murchison and A.C. Ramsay, all of whom were interested in the fact and the nature of a New Zealand Glacier Period. To begin with Haast appears to have taken the 'drift theory' for granted, presumably in consequence of his association with Hochstetter, but by 1864 he had abandoned it following

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two years of exploring on both sides of the Southern Alps. He had also corresponded with Hector who had become a confirmed 'glacialist'. The convictions of these and other early observers influenced the terms in which they described and interpreted glacial evidence in New Zealand (Haast, H.F., 1948, pp. 1024-53). What Caused the Ice Age? In New Zealand no less than elsewhere, the question of causes was a subject for debate throughout the period. The early observers, tacitly adopted whichever hypothesis best suited their ideas in other directions, such as when the Southern Alps were raised, and whether the land was depressed or elevated at the onset of glaciation. Otherwise the issue does not seem to have agitated them greatly. The fact that these islands in temperate latitudes had experienced intense glaciation, virtually down to sea-level in the southwest, had implications for the 'glacial theory', but until much later it was possible only to speculate as to whether the ice advances here had coincided with Northern Hemisphere oscillations - - a critical question for certain climatic hypotheses. Of early 20th century New Zealand writers on glaciation, the most prolific was Robert Speight, Professor of Geology at Canterbury College and Curator of Canterbury Museum in Christchurch. For many years Speight convened relevant committees of the Australasian Association for the Advancement of Science (later ANZAAS). He reviewed ideas on the subject of ice age causes (e.g. Speight, 1939) and from time to time satisfied public interest (locally strong perhaps because the regional port of Lyttelton saw the departure and return of several polar expeditions) by giving talks to the Canterbury Philosophical Institute, but neither he nor any other New Zealand geologist of the period could claim to have thrown important light on the problem. The Gold Rushes Traces of gold were noted by early settlers and explorers in various parts of New Zealand and worked on a small scale, but gold fever really struck in 1861 in Otago and three years later on the West Coast of the South Island. Miners by the thousand were quickly at work, at first using hand methods in the banks and beds of present streams, but soon followed by small companies set up to apply hydraulic sluicing to gold-bearing gravels showing in the faces of river terraces. In southern districts detrital gold was won partly from preQuaternary conglomerates whereas in Westland all but a small faction of it came from a Late Quaternary mantle of morainic and glacifluvial deposits covering much of the piedmont belt between the western base of the Southern Alps and the shore of the Tasman Sea; or from re-worked auriferous sands of both modern and tectonically-raised former strandlines. The latter lay close to the base of old seacliffs cut during interglacial high stands of seaqevel. This Westland region has yielded much information about the sequence of glacial events, some on a majestic scale, and also information upon non-glacial intervals, altogether representing both the Early and Late Quaternary. Nowhere else is the glacial story so fully and dramatically presented, but had it not been for the rich gold which led to so much digging and turning over of the glacial deposits containing it, that story might not have been told until much later, if ever. Mostly covered in dense rain-forest, cut off from the rest of

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the South Island by mountain ramparts, lacking in good natural harbours and otherwise unattractive for settlement, the region may well have remained undeveloped if the gold rushes of last century had not brought a sudden influx of population which forced the breakdown of those barriers. Mining operations also ensured continually renewed and freshened exposures of Quaternary deposits - - an important factor where the moist, temperate environment induces very rapid re-vegetation. The initial Westland rush was still new when Haast visited the diggings in 1864 and described the vast extent of glacial deposits west of the Southern Alps in a report for the Canterbury Provincial Council which administered the region at the time. After the original Geological Survey was established in 1865 under Hector, repeated examinations were made during the heyday of goldmining by Survey geologists, including S.H. Cox, A. McKay and the Director himself. Descriptions appeared periodically in the annual Reports of Geological Explorations up to the time of the demise of the old Survey in 1892 and thereafter in reports for the Mines Department and in the Transactions of the New Zealand Institute until the present Geological Survey came into being in 1905. Haast's vivid impression of the mining scene and the glacial features are recorded in his book Geology of Canterbury and Westland printed in Christchurch in 1879. A 35 page chapter on the 'Great Glacier Formation' embodies a map of the extended glaciers which is the earliest such map I have seen. Although the close association of rich gold concentration with moraines and their proximal outwash accumulations was noticed, it was a long time before anyone suggested that there might have been more than one great episode of glacier advance down the Alpine valleys to feed an extensive piedmont ice apron. Initially, the gold was assumed to have been derived from the Alpine rocks to the east, but later some toyed with a notion that part of the auriferous gravels had been eroded from vanished, presumably submerged land to the west of the present coastline. Alexander McKay is to be thanked for having left the best descriptions of what could be seen during the earlier mining operations before it was obliterated by mining or obscured by regenerating forest. In the final annual Report of Hector's Survey McKay (1894, pp. 45-6) described a moraine at Kanieri, near the town of Hokitika, as 'clearly the youngest of all the moraines outside the limits of the mountains'. This appears under a sub-heading 'Early Recent Deposits and Latest Extended Moraines' separate from another section headed 'Extended Glacier Deposits outside the Limits of the Mountains', these deposits being classified as 'Pleistocene or Newer Pliocene'. The above statement is the earliest I have found, based not on dogma but upon observed spatial relationships of deposits in one area, which clearly implies more than one ice advance over a substantial span of time. The context, moreover, recognizes an intervening episode of river degradation so that it was not a case merely of intermittent glacier recession. McKay was retained as Government Geologist for the Mines Department during the interim before the new Geological Survey under J. Mackintosh Bell was set up in 1905. In a 'Report on Goldfields of New Zealand' McKay (1893, p. 166) writes rather less confidently, indeed somewhat defensively, about this 'second advance of the Hokitika glacier at a time considerably later than the greatest extension of glacier ice', but there is no doubt that he must receive credit for being the first geologist to recognize the evidence for multiple glaciation which has since been verified amply in the Westland region and elsewhere.

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The 'Park-Marshall' Controversy

Scottish-born James Park came to New Zealand as a young man in 1874 with some scientific education including study under A.C. Ramsay at Imperial College, London. His professional career began a year or so later when he joined the old Geological Survey as an assistant and it culminated in nearly 40 years as Professor of Mining at Otago University, Dunedin. Park wrote many papers on geology, mining and metallurgy and several popular textbooks including a 'Geology of New Zealand' (1910). In 1902 he described a bouldery deposit near Dunedin as 'moraine' and inferred that the neighbouring hills, less than 700 m high, had borne glaciers during the Ice Age. Although not the first writer to float such an idea, Park was the first geologist to develop it into a major glacial hypothesis. Over the next few years on behalf of the revived Geological Survey he mapped in some areas of undoubted mountain-valley glaciation in central and west Otago and began to develop his theme that mighty glaciers had flowed out from the mountains to unite as an ice mantle covering most of the lowlands of the South Island, and at its maximum to join with the southern polar ice. In the North Island the volcanoes Ruapehu (2,797 m) and Egmont (2,518 m) were claimed to have borne ice down to their very bases, on the evidence of supposed 'moraines'. In other directions a shrewd and accurate observer who made many valuable contributions in stratigraphy and mining geology, Park became obsessed with his picture of a 'Great Ice Age of New Zealand'. Coming from a geologist with Park's standing these extreme claims naturally were taken seriously by some but they also provoked strong reaction headed, ironically, by his colleague Patrick Marshall, then Professor of Geology in the same University. More reasonable alternative explanations were indicated for the breccias of various ages and sundry rubbly, surficial deposits which Park could see only as till. The 'moraine' hummocks around the bases of the North Island volcanoes, for example, were shown later to be volcanic mudflows (Grange, 1931). Even after an independent, firm dismissal by a visiting English geologist (Trechmann, 1917) Park failed to recant and as late as 1924 was still describing Late Cretaceous and Eocene conglomerates in central and eastern Otago as Pleistocene till and fluvioglacial debris. While this rather absurd chapter did nothing directly to further knowledge of the New Zealand glacial Quaternary it served to draw attention to glacial geology in general and in particular to the problem of reliable criteria for recognizing ancient glaciations. Pliocene or Pleistocene?

The question whether or not the New Zealand glacial deposits were contemporary with those of the Glacial Period in Europe and North America arose soon after their discovery, no doubt from natural scientific curiosity. Before long it was caught up in a conflict of doctrines concerning the supposed history of elevations and subsidences of these islands and its implications for the Glacial Theory, as noted earlier. I must now digress to point out the difficulties in the way of founding a stratigraphy in this isolated country which is now known to have rocks representing every epoch since the Late Pre-Cambrian. Sound evidence for correlating geological events in New Zealand with Northern Hemisphere chronologies was scanty in the middle of last century, and the application of the terms 'Pliocene' and 'Pleistocene' conjectural and premature. We have to

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remember that the principles of stratigraphy and geological time were still evolving and the present-day disciplined use of properly defined terms was yet to come, with the sharpness of meaning and consistent use now demanded. The need for such discipline in the Quaternary was not appreciated because in most parts of the world (though not in some parts of New Zealand) deposits of that age (youth?) were principally surficial, in other words, hardly 'rock' at all! Indeed, the proper application of stratigraphic concepts and terms in the Quaternary was still being debated in the middle of the 20th century. Fossil collections mainly of mollusca made by Hector and his contemporaries from rich, thick Late Tertiary strata were sent to museums in Australia, Britain and Europe for identification, while some species were described by the collectors as best they could, with limited reference literature and virtually no comparative material. Many faulty determinations were made before it was realised how high a proportion of New Zealand fossils were endemic, and how premature it was to attempt overseas correlations. Eventually, an indigenous scheme of biostratigraphy developed, its immediate aim reliable internal correlations rather than global links. At first Quaternary deposits generally were treated informally or mapped as 'Drift' (though not necessarily with any glacial connotation), while the use of and distinction between 'Pliocene' and 'Pleistocene' remained vague. Compared with elsewhere, New Zealand Quaternary studies have been especially handicapped by the lack of a paleontology of the higher vertebrates other than birds and the absence of any trace of early man. Furthermore, the biota shows every sign of isolation from other lands from the Cretaceous until Polynesian man arrived with his neolithic culture, the dog and the rat about a thousand years ago. J.A. Thomson (1917a) put the classification and naming of New Zealand Tertiary strata and locally thick Quaternary sediments for the first time on a clear philosophical basis, and modern biostratigraphy throughout the column has evolved since on essentially the same principles. Separate definition of lithostratigraphic units for local and regional mapping was encouraged. All the same, considerable looseness remained, as became painfully apparent to the team of stratigraphers who undertook to compile the New Zealand volume of Lexique Stratigraphique International (Fleming (ed.), 1959). Having defined and named faunal 'Stages' for the Tertiary, Thomson recognized the unconformity in many areas separating more or less severely deformed Tertiary and older strata (up to and including his Wanganuian group of Stages) from post-orogenic Quaternary surficial formations grouped in a 'Notopleistocene' unit which never gained acceptance. Surficial deposits on the North Island west coast were locally named 'Hawera Series', a term which later authors extended in meaning to embrace at first all post-Pliocene and pre-Hoiocene (Finlay and Marwick, 1947) and then all post-Pliocene deposits (Suggate, 1961a). Developing a climate-stratigraphic scheme, Suggate at the same time introduced Aranuian Stage based on an excellent record of Holocene warming and marine transgression from borehole data near Christchurch. As additional fossil taxa, including planktonic microfossils, were worked on and their ancestral affinities deciphered, New Zealand geological history had become by the end of the period under review, relatively well integrated with international time divisions. (See e.g., Fleming, 1979; tables on endpapers of Geology of New Zealand, Suggate, 1978.) Returning to the dating of New Zealand glaciations, Haast in 1861 wrote of the 'Great Glacier Period' and subsequently referred it to the 'post-Pliocene' and eventually to

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'Pleistocene'. Hochstetter (1864) formally classified the ancient glacier deposits as a subdivision of: 'Post-Tertiary (Quaternary and Recent) Rocks' (Fleming trans., 1959, pp. 24-5). Hutton (1873) was not deterred by the inability to apply European fossil criteria for distinguishing Pliocene and Pleistocene here. He declared the glaciation of New Zealand to be a Late Pliocene event, in his view directly due to sharp uplift of the mountains and not necessarily synchronous with the 'cold glacial period' in the Northern Hemisphere. Subsidence followed, then renewed uplift to explain certain glacial features in Otago which he suspected to be younger and called 'Pleistocene'. There followed a good deal of speculative debate, tedious to read, about the supposed elevations and subsidences of New Zealand since the Miocene. Datings of glaciation tended to accord with authors' views in these matters, but there was little real evidence. Hutton, a philosopher and a versatile natural scientist had left the Geological Survey to become Curator of Otago Museum and a Professor at the University. Although responsible for some of the best early paleontological and stratigraphical work in New Zealand Hutton adduced fossil evidence against a Pliocene cooling of the surroundings while reaffirming his earlier conclusion that glaciation was simply the result of mountain uplift and there had been no Great Glacial Epoch in New Zealand (Hutton, 1876, p. 387). Haast (1879) dates the 'Great Glacier Formation' vaguely as older than 'Quaternary and Recent' surficial deposits. Hector, McKay and most recent authors gave 'Pleistocene' as the date of glaciation but suspicion was growing early in the present century that surrounding seas did begin to cool in the Late Pliocene (e.g. Marshall and Murdoch, 1920, p. 126). By 1944 this cooling had been substantiated by Fleming on evidence of northward migration by elements of the molluscan fauna. About the same time Gage (1945, 1961b) described, from near Ross in Westland, a succession of tills and glaciolacustrine beds strongly deformed along with conformably underlying marine sandstone with fossils immediately older than the North Island strata from which Fleming inferred the Late Pliocene cooling. Plant microfossil determinations (Couper and McQueen, 1954) later confirmed the correlation of this cooling with the Ross Glaciation deposits, which are overlain strongly unconformably by Late Quaternary glacial beds. Until 1948 it seemed that the discovery of the Ross Glaciation meant a vindication of Hutton's Pliocene date for the main event. In that year, however, a recommendation at the International Geological Congress in London for placing the Plio-Pleistocene boundary at the level of the first indication of post-Pliocene cooling had the effect of transferring the Ross Glaciation into the Early Pleistocene. That was still the accepted position in 1965, but recent advances in geochronometry have reversed the situation.

How Many Glaciations? McKay's 1893 account of Westland gold deposits contained the earliest suggestion supported b.y field evidence that the Ice Age at least in that region comprised at least two Pleistocene advances with intervening warming and retreat, rather than a single advance with intermittent recession. Neither Haast nor Hector seem to have considered more than one advance up to this time. McKay may have had suspicions earlier, but by 1893 he was no longer responsible to Hector for compliance with official views and it is surprising that he still seemed diffident about grasping the nettle of multiple glaciation. Hutton (1873; also

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Hutton and Ulrich, 1875) first declared a Pliocene date for the main event and later spoke of another in the Pleistocene, but not on firm evidence, as we have seen. In the first of a new Bulletin series from the revived Geological Survey, Bell and Fraser (1906) remapped the Hokitika district of Westland, part of the area McKay described in 1893. The possibility of 2 or 3 minor re-advances is admitted (p. 85) but the concept was still essentially 'monoglacial' - - the Ice Age having been initiated by a crescendo of alpine uplift from Miocene onwards culminating in the Pleistocene, with or without global cooling. Leaving McKay aside, serious consideration of two or more distinct glaciations in New Zealand (not merely minor oscillations) perhaps had to await the stimulus of Penck and Briickners 4-fold glaciation of the European Alps. Morgan (1908) dealing with an adjoining region south of Hokitika, and Park (1908) describing central and western parts of Otago followed a similar line, as did P.T. Cox, Ferrar, R. Speight and other authors over the next 30 years. There were other views, however. John Henderson, originally a mining geologist with some interest in landforms and later to become Director of the Geological Survey, surveyed the geology and mineral resources of the Reefton district, about 120 km north of Hokitika. Despite some confusion because his distinction between 'Pleistocene' and 'Recent' differed from that of McKay and others, it is clear (Henderson, 1917, p. 90) that Henderson regarded the formation of 'Recent' moraines and fluvioglacial gravels within montane valleys as a separate event from that which had left 'piedmont glacier deposits', remnants of which survive on dissected upland areas near Reefton. Incidentally, no glaciers exist in the region today. Recognition of uplift and valley-deepening having intervened between advances is implicit rather than explicit (Henderson, 1917, pp. 97, 101). The firming of Henderson's conviction and that of others in succeeding years was due not so much to new data perhaps as to the increasing acceptance overseas of multiple glaciation. Morgan for example, by 1926 was predicting that more than two glaciations eventually would be recognised in Westland. Henderson was notoriously cautious but by 1931 he could confirm that the entire region of Nelson (Reefton is in its southwest corner) had experienced two periods of Pleistocene ice advance separated by a warm interval long enough for valleys to be deepened well below the floor of the earlier ice, and before re-occupation and modification by a later advance. Other Quaternary workers of the period, whatever their beliefs about multiple glaciation elsewhere, continued to hold the monoglacial view as regards New Zealand mainly because of failure to find interglacial deposits demonstrably intermediate in age between glacial deposits. Even today we know of few straightforward examples but circumstantial evidence is compelling. Moreover, we appreciate that the tempo of Quaternary tectonic movements and erosion in glaciated parts of New Zealand does not favour preservation of such evidence, and you need luck to find it. Following a gap due to the depression of the thirties a younger generation of New Zealand geology graduates (the writer is one of them) began to take the stage and more young geologists came to this country immediately after World War II, including R.P. Suggate. Quaternary glaciation was not a major interest of any of them to begin with, although Willett (1939) wrote about a re-advance of ice over older moraine in Central Otago, and (Willett, 1940a) prepared a summary of views up to that time about the number and possible overseas correlation of New Zealand glacial events for the Sixth Pacific

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Science Congress. The newcomers may have been less inhibited than their elders in such a departure from local tradition as multiple glaciation. For instance, Wellman and Willett (1942) returned from an arduous reconnaissance of a remote tract of coastal South Westland and West Otago with evidence for at least two periods of ice advance from enormous accumulations of morainic deposits. They noted physiographic evidence for strike-slip displacement on the Alpine Fault, a great dislocation along the western base of the Southern Alps. Three years later Wellman geologically mapped the northern part of the previously reconnoitred strip of South Westland (Wellman, 1951, 1955a), provisionally naming three glaciations comprised of two piedmont advances separated by a warm interval of interstadial value and a subsequent valley glaciation. To these Wellman added an earlier 'Upper Tertiary' event, being that described from Ross by Gage (1945). It was the first recognition of four glaciations and the first naming of glacial events in New Zealand. The grounds for distinction were similar to those Henderson had used at Reefton. Wellman is perhaps best known beyond New Zealand for his hypothesis first proposed at the 7th Pacific Science Congress in 1949 (Benson, 1952), now universally accepted and embodied in modern pl~te-tectonism, claiming that the modest strike-slip offsets of Pleistocene features by the Alpine Fault are of the right order and sense to be compatible with much greater offsetting of pre-Quaternary structures and rocks as old as Permian by as much as 560 km (Wellman, 1952, 1956). In a sectional chairman's address to the 8th Science Congress of the Royal Society of New Zealand in 1954 Wellman (1955b) included relative amounts of fault displacement as well as differential weathering, etc., among criteria for estimating relative ages of fluvial and fluvioglacial features, assuming a constant tempo of movement through the Pleistocene. Remapping the Reefton district between 1948 and 1950, Suggate (1957) confirmed Henderson's distinction of a 'Piedmont Glaciation' from two subsequent valley glaciations. The valley advances - - less extensive than the Piedmont Glaciation - - were given status comparable with stadials of the WOrm Glaciation in Europe, and correlated tentatively with Wellman's 'Alpine advance'. More diffidently, the Piedmont Advance was identified with the 'Kinnaird' and 'Paringa' advances in South Westland, but Suggate stressed that these were no better than informed guesses. The areas concerned are 300 km apart, radiocarbon dating was not available when the mapping was done and knowledge of intervening glaciated areas, largely overgrown since goidmining declined, had scarcely progressed since McKay's day. There was little encouragement for attempting to connect the evolving South Island glacial chronology with the longer-studied Pliocene-Pleistocene marine biostratigraphy and paleocology which Fleming in particular was revising and refining in the almost nonglaciated North Island. Yet it seemed likely that Fleming's series of climate oscillations should somehow be reflected in corresponding ice advances and ice-free intervals in the South, but there were obstacles to correlation across Cook Strait. The only common points reasonably established were the cool, lower part of the Nukumaruan Stage (Hautawan substage) in the North and the Ross Glaciation. Until (or unless) it was certain that the full number of climatic events were represented in each area, correlation by 'count-down' was hazardous. Fleming (1956) took the plunge at the Fourth INQUA Congress in 1953, tentatively correlating the North Island marine with the South Westland glacial sequence (Weilman,

201

Glaciation in New Zealand

1951) - - that being the only named succession - - and with the European Quaternary. It was a bold step, yet although there have since been amendments and elaborations in both marine and glacial chronologies Fleming's trial integration of them in 1953 must be recognised as a major turning point, and acceptance at the time a tribute to his standing as a scientist as well as an expression of hope and confidence in the eventual outcome of a comprehensive New Zealand Quaternary chronology. CORRELATION WANGANUI MARINE CHRONOLOGY FLandrian UPPER PLEISTOCENE

l~Istages : (/~

IWESTLAND GLACIALJ R O S S ICHRONOLOGY J SEOUENCE post-glacial |

CLIMATE

glacial glacial m i l d , moist

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T'~J TERANG,AN iiiiiii!iiii iiiiililili::::i::iii!i!U n c o n for m i'

temperate 03 LU

LOWER

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~ubtropicat seas coot seas

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WAITOTA RAN

:ooling ~ubt.ropicot, seas ;old seas and g racial.ion cooling ;ubtropicaL seas

FIG. 2. First correlation chart linking Pliocene/Pleistocene North Island marine succession with named glacial events in South Island. (From: Fleming, 1956.)

Aerial Photography Prior to the Second World War New Zealand was very poorly covered by topographical maps. The entry of Japan in 1941 prompted a crash-programme of topographic mapping on a 1:63,360 scale for military purposes, and although at first the surveying methods were crude and contouring unreliable, geologists welcomed the maps. Unsystematic oblique air photography of little cartographic value had been going on long before good quality vertical airphotos began to be available from the mid-thirties, the usefulness of which in geology was quickly realised (Willett, 1940b). Photogrammetric facilities were severely limited until well after the war ended, but by 1945 photo coverage had reached the forest-covered glaciated tracts on the South Island west coast. As an expedient while the map-making bottlenecks remained, skilfully mounted mosaics were issued for regions of moderate or low relief as well as runs of single photographs. Non-stereoscopic and a poor substitute for photogrammetry on uniform scales, mosaics nevertheless presented an aerial overview not achievable from study of stereo-pairs and showed fine topographic detail, a particular boon in areas like Westland where ground surveying is often hampered by dense vegetation and wet weather.

202

M. Gage

The Geological Survey staff in Westland at this time included R.P. Suggate who, officially concerned with coalfield geology, had become interested in the glacial features; also H.W. Wellman, a keen advocate of photogeology. Impressed by the long, sinuous moraine loops, overflow channels and outwash surfaces which could with fair accuracy be transferred from airphotos to the available maps, Suggate set about compiling an overall picture of glaciation features on the North Westland piedmont and also of cliffs and former strandlines marking previously higher sea-levels. The result was not only a great advance over earlier rough mapping but also verification of McKay's claims of multiple ice advances. Using altimeter heights Suggate was able to inter-relate dissected outwash surfaces with successive end-moraine loops, tracing them in vertical profile to the coast and establishing relationships with marine terraces, beach deposits and associated interglacial peats. Not published until some years later, this was important pioneer work in the proper mapping and classification of glacial sequences in what has come to be regarded as the most critical region. o I

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External Contacts and Overseas Experience Isolation and remoteness were deeply felt by both amateur and professional scientists in New Zealand in the early part of the period, despite achievements in building up libraries in the more populous centres. Exploration voyages such as those which brought Hochstetter and Charles Darwin to these shores were few and far between, and travelling time let alone cost deterred independent scientific visitors. Intercourse with Australia was easier, especially after the Australasian Association for the Advancement of Science came into being. This organisation maintained a Standing Committee on Climatic Change, but Quaternary glacial phenomena commanded relatively less importance across the Tasman Sea. Amongst visiting scientists in the early 20th century, in this context one should mention C.T. Trechmann whose outside assessment of the Park-Marshall dispute has been noted above, and Carl Caldenius who came from Sweden in 1933 to examine varve sequences, hoping to link them by 'telechronology' with the Northern Late-Glacial. Caldenius did not stay here very long, no doubt having quickly realised that the climatic significance of varves was not the same in oceanic, middle-latitude New Zealand as in the northern continental higher latitudes. But he did collect samples for pollen study, and made possible Lucy Cranwell's introduction to palynology (see later; McKellar, pers. commun.); this had far-reaching consequences.

Glaciation in New Zealand

203

The Second World War years were unfavourable for scientific travel to or from New Zealand except that connected with defence. Post-war strategic interests combined with great advances in polar travel and communication led to an upsurge in Antarctic exploration. The U.S. Navy's 'Deep Freeze' base at Christchurch Airport became a major stepping-off place for scientists, chiefly American, bound to or from the Far South. This annual flux naturally included many with experience in glacial geology as well as in glaciology, and some (notably A.L. Washburn and R.P. Goldthwait at this stage) returned later for extended research periods in New Zealand. Some valuable contacts were thus made at this critical period, giving the confidence so badly needed by New Zealanders working on our Quaternary glacial succession. Other visitors, most of whom subsequently published their New Zealand work, included Cuchlaine King from Nottingham, Paul Woidstedt from Bonn, Lee Clayton from North Dakota; many more were to follow. Taking stock of the situation in the early 1950s we note that although the 'younger generation' referred to above had had no concern with glacial geology in other parts of the world, it was fully appreciated that some kinds of material upon which the correlation and subdivision of the European Quaternary is based were not to be hoped for here. Unequivocal interglacial sites were lacking. A complex glacial history was now evident, but internal correlations remained speculative and overseas ones even more so. Knowledge could be summed up thus: the Ross Glaciation was an Early Pleistocene event, its stratal evidence distinguished by effects of the Kaikoura Orogeny climax and separated by unconformity from that of an uncertain number of Late Pleistocene advances with warm interludes. The duration of the hiatus was unknown. Continuing Quaternary tectonism limited the confident use of glacio-eustatic correlation. While Suggate was tackling the glaciation sequence in Westland Gage joined the Geology Department of Canterbury College in Christchurch and was taking students on field trips into the glaciated montane valley of the Waimakariri River to see morainic, glacifluvial and ice-erosional features on a spectacular scale. Former geology professor and glaciologist Robert Speight had described moraine loops and terraced outwash systems in the Waimakariri (Speight, 1938) and other Canterbury valleys in terms of a single Pleistocene advance with minor fluctuations interrupting final retreat into the headwaters, where small glaciers exist today. Interglacial evidence was elusive; it has since been found, but many years later. Rather inclined to see more than one glaciation in the Waimakariri evidence, Gage deferred to the authority of Speight. Among the post-war gains was the possibility for New Zealand scientists to spend time abroad through study-leave privileges and support from research foundations such as Fulbright, the Commonwealth Fund, Royal Society (London) and Nuffield, etc. Suggate and the author were among several who benefited from opportunities to examine classic Pleistocene localities in Western Europe and America and to meet Quaternary workers in various fields; also to attend INQUA and other international meetings. Gage spent parts of 1952 and 1953 at the University of Illinois, where the Geology Department and the nearby State Geological Survey combined to make the place a very active centre for Quaternary research. Having seen in the Mid-West, the Rocky Mountains and the Sierras the accepted evidence for distinguishing and correlating glaciations, Gage felt that similar criteria should work in New Zealand. On his return, though still hampered by the lack of topographical maps, he set out to record glacial evidence in the Waimakariri valley, recognising five

204

M. Gage

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Glaciation in New Zealand

TABLE 2. P. Woldstedt's (1961) attempt to correlate New Zealand with European Pleistocene (Warm periods in italics) Wanganui District*

South Island

St Johns Alluvium

Europe

Younger Advance K 2, K 3

Interglacial?

Lamplough Interglacial??

Rapanui Form.

Wlirm

Otiran

Wtirm ?

Eem ?

Older Advance (K 1)

Oturian

Karoro

Brunswick Form.

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Ohe ?

Riss

Riss I ?

Holstein

cold Kaiatea ~ warm Formn. ~ cold

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k warm

Cromer

Cold period (unknown)

Giinz

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Okehuan

Eburon

Marahauan

Hautawan

Tegelen

Ross Glaciation

Brfiggen (= Pretegelan)

* From Fleming (1953). tDiffers from Suggate (1965); there in Awatuna Formn. $ Moraine in Clutha Valley, Otago.

TABLE 3. Relation between climate-stratigraphic stages, local glacial events, and lithostratigraphic mapping of deposits. Correlations according to Suggate 1965

North Westland Lithostratigraphical units (Formations) Glacial events

Climate-stratigraphy stages

Canterbury (Waimakariri Valley) Lithostratigraphical Glacial events units (Formations)

Aranuian

Moana

Kumara-3 advance

Loopline-2

Kumara-2(2) advance

Loopline-I Awatuna Waimea

Kumara-2(1) advance

Otiran

Kumara-1 advance

Oturian Waimean

Karoro Cockeye

Hohonu advance

Terangian Waimaungan

Albion Porika

Porika glaciation

Waiwheran Porikan

Jones

Ross glaciation

( Hautawan* )

* Biostratigraphic stage, but reflects a cool climate phase.

l Poulter advance Blackwater I, II advances Otarama advance

Springston St. Bernard Burnham Windwhistle

Woodstock advance

Woodlands

Avoca glaciation (pt.)

Hororata

Avoca glaciation (pt.)

Hororata

206

M. Gage

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Glaciation in New Zealand

207

advances, one comprising 2 or possibly 3 stadials. His work was well advanced in 1957 when Suggate moved to Christchurch, having completed a similar mapping exercise in the Taramakau valley of North Westland. Glaciation sequences independently inferred in these two valley systems on opposite sides of the Southern Alps had so much in common that it was decided jointly to prepare trial trans-alpine correlations and a tentative glacial chronology to be presented at a meeting of A N Z A A S in Dunedin (Gage and Suggate, 1957) together with an assessment of the reliability of criteria used overseas for regional correlation in New Zealand (Gage, 1957). These papers were illustrated by maps showing the inferred ice-limits in the larger South Island valley systems. Encouraged by the good reception given to the papers at ANZAAS Gage and Suggate (1958) published the classification, slightly amended and named, with an account of the criteria proposed for recognising New Zealand glacial 'Stages'. Gage also published (1958) the Waimakariri Valley glaciations in detail. With successive amendments and additions as other valley systems were studied (e.g. Gage, 1961a; McKellar, 1960; Soons, 1963; Speight, 1963, Suggate, 1963) the scheme evolved into that of Suggate (1965a).

Palynology and Radiocarbon Dating For those involved in the progress of the late 1950s, satisfaction from achieving some sort of glacial chronology in the South Island with reasonably confident valley-to-valley correlation was tempered by knowing that we still had rather less than half the story. The named sequence of ice advances was no more than an ordering of the evidence for geological events attributed to cool climatic oscillations. It was uncertain whether every cool phase had caused an ice advance or whether the record of every advance had survived. Particular advances doubtless had resulted from the same cooling episodes as had produced solifluction and other non-glacial cold climate effects described from the southern part of the North Island (e.g. Cotton and Te Punga, 1955) but correlation was conjectural. Both regions being subject to vertical tectonic movements, tilting and warping, the altitudes of elevated marine features in the North Island attributed by Fleming (1953) and Brothers (1954) to interglacial high sea-levels could not be applied confidently to correlation with similar features in the glaciated South. Opinions about relative durations and warmth of non-glacial intervals in the south were based subjectively upon the amount of geological change achieved, such as depth and intensity of weathering, depth of downcutting by interglacial streams, with little support from quantitative data as to the tempo of such processes in New Zealand conditions. The Quaternary climatic chronology was indeed a fragile structure. New Zealand Quaternary surficial deposits are practically barren of animal fossils except for scattered, though locally rich, finds of snails and of bird remains in Holocene swamps. Peats from these swamps and from buried peaty layers in older Quaternary deposits had not, in the review period, been made to yield fossil insects, but were known to contain abundant plant debris - - wood fragments, pollen grains, spores, etc. Prior to the First World War some botanists (such as-L. Cockayne) had turned to geologists (such as R. Speight) interested in Quaternary glaciation for help in unravelling the later history of New Zealand's highly endemic forest flora, with special attention to how it had fared during the 'Ice Age'. The glacial history was then too vaguely known to be very helpful. Modern techniques for preparing and studying plant fossils had been applied earlier, but

208

M. Gage

the use of plant microfossils in Quaternary vegetation history seems to have begun with the enthusiasm of Lucy M. Cranwell following a period of study in Sweden (Cranwell, 1938; Cranwell and von Post, 1938). Thereafter it was developed by W.F. Harris, R.A. Couper, N.T. Moar and others more recently. At first focus was largely on the floral record of the last few thousand years of 'post-glacial' time. Couper, a paleobotanist in the wider sense, had worked mainly in the pre-Quaternary and on the possibility of integrating marine and non-marine stratigraphies with the help of plant microfossils. From about 1954, however, Couper contributed much to our knowledge of the Quaternary flora and its response to environmental changes (Couper and McQueen, 1954). Although New Zealand plants did not evolve fast enough through the Quaternary to favour their use as index fossils it was seen that pollen spectra could illuminate climatic events that could be integrated with glacial and other geological evidence. Thus, Couper and Harris (1960) demonstrated climatic cycles from plant microfossils in Pliocene/Pleistocene drill cores in the South Auckland district, since when there have been many Quaternary applications. New Zealand had its own 14C laboratory operating in 1951, one of the first south of the Equator. Its services were soon in heavy demand for ageings relative to early Maori history and culture and for adding the absolute-time dimension to Quaternary and 'post-glacial' pollen stratigraphy. Amongst the earliest application to Quaternary glacial events was a 22,300 _ 350 BP age for a cool flora in North Westland at the onset of a stadial of the Otira Glaciation (Gage and Suggate, 1958, p. 596); and 15,000 _ 200 BP for peat in an overflow channel abandoned by the receding Hawea Glacier in Otago (McKellar, 1960, p. 453). Non-glacial cold-climate evidence from near Wellington was dated by Brodie (1957). (See also Suggate, 1965a, p. 84; periodic listings of New Zealand 14C results can be traced from bibliographic entries under Fergusson and Rafter, Grant-Taylor and Rafter, in Warren et al. , 1977.) Other dating methods that would eventually extend the range beyond Late Quaternary had not yet become available, nor had the tephrochronology of the North Island volcanoes been worked out. Names like Arrhenius, Emiliani, Erikson and Wollin, Woldstedt and Zeuner were familiar by 1965, but it was too soon to realise that the key to calibration of our Quaternary climatic chronology would be found beneath the floors of the oceans. The 1:250, 000 Geological Mapping Programme

By the late 1950s the lack of complete geological map coverage of New Zealand on a scale larger than 1:1,000,000 was considered scandalous. Having in mind not only the approaching centennial of the N.Z. Geological Survey in 1965 but also the possibility of an invitation for the International Geological Congress to come to New Zealand in 1964, the Director, R.W, Willett was determined to concentrate the Survey's resources upon a vigorous, new mapping programme to cover the country in 28 sheets at a scale of 1:250,000. The project took 11 years to complete, and immediately precipitated the need for urgent decisions on many questions of stratigraphy and terminology for the sake of consistency in the map legend for the series. Since so much of the face of these islands bears a mask of Pleistocene deposits - - marine, fluvial, periglacial, volcanic - - usually thin but locally up to hundreds of metres thick, the Quaternary was no less important than the older strata. Generalship of the compiling and gap-filling teams was allotted by Willett to Suggate, then head of the Regional Geology Section. Suggate himself took steps to pull together all

Glaciation in New Zealand

209

available evidence for Quaternary glaciations, warm interludes and sea-level fluctuations along with the rest of the marine, volcanic, tectonic and other Quaternary data. Guidelines were laid down as regards different categories of data, orders of magnitude of climatic events, etc. New units and names were to have proper definition and type localities and validation, and long-standing problems were faced up to for the first time. Inevitably, some of the correlations adopted for this map series were disputed. Insofar as it concerns glaciations and related matters, the outcome of this timely and beneficial exercise was publicised in a Bulletin of the Geological Survey (Suggate, 1965a), which gave the proposed scheme an official aspect and it was widely used outside the institution. Despite disagreements about correlation and status of events that have arisen, I am convinced that without the stimulus of the 1:250,000 mapping project our knowledge of the New Zealand Quaternary may well have remained in its former fragmented state for a long time, and we would have been less well prepared for the next great challenge, which was to present it to the Ninth INQUA Congress in Christchurch in 1973.

Glacial Cyclothems? Marine Pliocene and Early Pleistocene sediments up to 5 km thick and now strongly deformed in places were laid down in tectonic basins in the Wanganui, Wairarapa and Hawkes Bay regions of southern North Island and parts of the South Island. From Late Pliocene onwards, certain North Island sequences show systematic variations in lithology and texture reflecting rhythmic changes in sedimentary tempo and water depth which, along with minor unconformities, were attributed by Vella (1963) to eustatic oscillations of sea-level 'relative to the lithosphere', in turn reflecting global temperature fluctuations and great expansions and withdrawals of glacier ice. The suggestion provoked much informal discussion at the time, critics observing the difficulty of eliminating possible direct effects of tectonic pulses in the sediment source areas, which Vella acknowledged, and the more esoteric question of identifying appropriate bench marks. Nevertheless, it was generally agreed that eustatic accompaniments of the Early Pleistocene glaciations would have made some mark in the marine sedimentary record of that age. Since 1965 ocean floor drilling has shown ecological cycles related to dated climatic oscillations.

New Zealand Glacial Climates Concurrently with research into the history of Quaternary glaciations there have been enquiries more broadly directed towards the nature of contemporary climates in New Zealand. The picture that emerged by the end of the review period was one of moderation. Extreme variations of temperature are not indicated; precipitation need not have varied greatly in the long term; westerly wind directions predominating today seem to have prevailed through the Quaternary too, with alternations between the NW and SW quadrants. South-to-north excursions by the biota have been detected but extinctions that could be blamed essentially on climate are few, while post-glacial vegetation recovery has sometimes been very rapid, from unglaciated refugia and perhaps with migration along belts seawards of the present coastline (Holloway, 1954; Wardle, 1963). Willett (1950) claimed that the snowline was about 1 km lower than its present elevations of about 1.8 km in the far south and 2.5 km in central North Island (and higher in the east at

210

M. Gage

any latitude). Temperatures were inferred to have been about 5-7°C lower. These estimates were made before the pattern of multiple glaciation had been worked out, and purported to give a composite picture for the cold periods. Today they are seen as applicable only to the Otira Glaciation, and thought to be excessive. Also held to be exaggerated are the areas of both main islands which Willett believed to have been denuded of forest and subject to periglacial conditions. In a review prepared for a Pacific climates symposium at the Tenth Pacific Science Congress in Honolulu in 1961, the author (Gage, 1965, 1966 with bibliography) concluded that although small-scale patterned ground develops today at high altitudes and soliflucted debris has been recognised in the south of the North Island and the east of the South Island (Cotton and Te Punga, 1955; Soons, 1962) no suggestions of permafrost can be confirmed, even in the far south. On the contrary, the character of the glacial deposits and of inferred associated geomorphic processes indicate strongly that flowing water was generally present and abundant. It was a glacial climate in which, although temperatures were lower and glaciers extended because of weaker ablation regimes of shorter annual duration, winters were never unbroken seasons of deep freezing; rather they were diversified by spells of above-freezing weather wherein running water was an active ubiquitous agent. This is consistent with the occurrence of vigorous gelifraction and solifluction but absence of permafrost. Loess is widespread and locally up to 10 m thick in some central and southern districts, and long ago was being recognised as an indication of former cold climate (Hardcastle, 1890, 1891). Glacio-eustatic depression of sea-level produced climatic side-effects. Increasing the land area by probably as much as a quarter, and closing both Cook Strait and Foveaux Strait (Te Punga, 1953; Fleming, 1962, Fig. 11, 1979, p. 82), it slightly increased the continental tendencies of inland climates. The coastline at such times being less deeply embayed, the moderating effect of the ocean upon inland temperature was diminished. Suggate (1950) demonstrated a positive relationship between short term glacier oscillations in Westland and cumulative departures from mean annual precipitation. Since large valley and piedmont glaciers did develop in that region despite the temperature moderating influences of the nearby ocean and the likely cloudiness of the alpine belt, one cannot rule out precipitation changes as having been a factor also in Pleistocene glacier fluctuations of the larger order. At the same time, periglacialphenomena elsewhere, especially east of the Alps, indicate that temperatures were lower than now, and conceivably glacial advances could have resulted from weakened ablation with little or no change in precipitation. Historic fluctuations suggest that the Westland glaciers with steep gradients, exposed to abundant sources of moisture on the western side of the Alps, respond sensitively to variations in either factor. A Pleistocene temperature change of 2-3°C might have been enough, in terms of glacier expansion or retreat, to match a five-degree change east of the Alps. Alpine climate in relation to glaciers has been investigated in the past two decades, but there is still much to be learned. CONCLUSION The foregoing is not claimed to have exhausted every aspect of New Zealand's glacial quaternaria, but I hope it presents a balanced picture of the advances along several

Glaciation in New Zealand

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important paths by which the culmination of 1965 was reached. Detailed histories might be written, for example, about glacial landform studies, the 'late glacial', soils and loesses, volcanic ash showers as an aid to geochronometry, and the campaign to clarify and ensure consistent usage of stratigraphic and other terminology - - an exercise in which Suggate played a leading part (e.g. Suggate, 1958, 1965a, b). The problem of overseas correlation has not been stressed, but that does not mean it has been overlooked. During the review period it remained secondary to the task of establishing a sound New Zealand chronology, although the apparent discrepancies between the New Zealand glacial succession and that of other countries which might have been expected to be similar received attention (Gage, 1965b). The post-1965 review has new lines to follow and the work of many new investigators to report. As regards the glacial classification and nomenclature, a major revision is now due, but it seems unlikely that the basic tenets of Suggate (1965a) will be abandoned. ACKNOWLEDGEMENTS I acknowledge gratefully the assistance of Sir Charles Fleming and Dr Ian McKellar, whose comments on the draft manuscript were valuable and encouraging; also that of Dr Vince Neall, from whom came the germ of the idea, for technical help.

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