A selection of notable NZ papers in geology & geophysics

Chosen by Simon Nathan, Ministry for Culture & Heritage

The hazards of persistent marine pollution: drift plastics and conservation islands

MURRAY R. GREGORY

Journal of the Royal Society of New Zealand 21(2): 83-100  [1991]

Plastic litter and debris of all kinds is conspicuous on many contemporary shorelines, most frequently near populated and industrial centres but also on remote and seldom visited or uninhabited islands, including Raoul, Campbell and Auckland Islands. Pollution by plastics is aesthetically distasteful and unnecessary, and also creates a number of environmental problems: e.g. death and/or debilitation of wildlife through entanglement; blockages to the intestinal tract through ingestion leading to starvation and death, or ulceration of delicate tissues by jagged fragments; reduction in quality of life and reproductive performance. Larger items may also hazard shipping. An encrusting pseudoplanktic biota similar to that found on floating Sargassum and other seaweeds has been recognised on drift plastics. Alien species, rafted on drifting plastic, could endanger the flora and fauna of protected and conservation island ecosystems.

The sources of plastic pollution can be both distant (the truly 'oceanic' debris which has drifted from afar) and regional and local (e.g. shipping, fishing and recreational boating activities). Data compiled during a recent clean‑up campaign on beaches of the inner Hauraki Gulf islands suggest that nearby land‑based sources are also important.

There is need to educate the public about the environmental problems arising from the indiscriminate disposal of plastics and other persistent synthetic compounds. It is unlikely that these problems can ever be solved by regulation, although, along With technological advances, that could alleviate them.

Keywords plastics, pollution, environmental hazards, Hauraki Gulf, conservation islands, endangered taxa, ecosystems at risk, management.

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The North Canterbury earthquake of September 1, 1888

H.A. COWAN

Journal of the Royal Society of New Zealand 21(1): 1-12 [1991]

On September 1, 1888, an earthquake of probable magnitude M7‑7.3 struck the Amuri District of North Canterbury, 100 km north‑west of Christchurch, New Zealand. The earthquake ruptured a segment of the Hope Fault, and damaged buildings over a wide area. The effects of the earthquake indicate Modified Mercalli intensities of MM IX in the epicentral area. High‑intensity isoseismals (>MM VII were strongly elliptical and parallel to faulting, apparently attenuating steeply to the northwest and southeast, respectively. However, in parts of Greymouth and Christchurch, shaking was amplified (to MM VII presumably by local ground conditions.

After the earthquake, dextral offsets of between 1.5 and 2.6 m were observed on fencelines crossing the Hope Fault at four localities in the Hope Valley. Recent field work has indicated that the ruptured section forms a structurally distinct segment ‑ the Hope River Segment ‑ of the fault. It extends 30 ±5 km along the Hope Valley, between two basins developed at releasing bends in the Hope Fault zone. 1 infer that the earthquake was initiated beneath the Hope‑Boyle Basin at the western end of the Hope River Segment, and propagated eastward until it was stopped in the Hanmer Basin. These inferences are supported by contemporary accounts of the effects of the earthquake, and are consistent with observations of earthquake faulting documented in recent international studies.

Keywords Amuri District, Glynn Wye, Hanmer Basin, Hope Fault, Hope River segment, fault displacements, felt intensities, releasing bends, Modified Mercalli scale, rupture arrest

Comment This paper summarises the contemporary observations made on the North Canterbury earthquake of September 1st 1888, and gives a geological interpretation of the tectonics and faulting.

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Tephra studies in New Zealand: an historical review

DAVID J. LOWE

Journal of the Royal Society of New Zealand 20(1): 119-50  [1990]

The development of tephra studies in New Zealand may be divided into four main periods: Period 1, late 19th century to late 1920s; Period 2, late 1920s to early 1950s; Period 3, early 1950s to 1973; Period 4, 1973 to late 1980s. The important events and advances that characterise each of these periods, and their causes and influences, are described with reference to contemporary scientists and their publications. Period 1: determination by dendrochronology of first numerical age of a prehistorical eruptive (Burrell Lapilli); first isopach map (Tarawera Tephra). Period 2: first tephra mapping in central North Island (for soil survey). Period 3: first use of 14 C dating; establishment of late Quaternary tephrostratigraphic framework by 'hand‑over‑hand' mapping in central North Island and Taranaki; initial development of tephra 'fingerprinting' using laboratory methods; application of tephrochronology to many disciplines. Period 4: revision and refinement of proximal stratigraphy, particularly in central TVZ calderas and on Mayor Island; extension of tephra mapping to distal regions, on and offshore, and to older deposits; advances in tephra correlation and dating methods; new tephrochronological applications; revolutionary studies of pyroclastic deposits for determining nature and effects of eruptions (physical volcanology and petrology); renewed awareness of volcanic hazards associated with tephra eruptions. The advances relate to indigenous, external, and 'individualistic' factors. They generally parallelled overseas trends but in some topics preceded or lagged behind them. Tephra studies, or "tephrology", may be regarded as having "come of age" early in the 1980s, about 100 years after the first tephrostratigraphic studies in New Zealand.

Keywords Tephrostratigraphy, tephrochronology, volcanic ash, pyroclastic deposits, volcanology, history of science

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A review of late Quaternary silicic and some other tephra formations from New Zealand: their stratigraphy, nomenclature, distribution, volume, and age

P. C. FROGGATT and D. J. LOWE

New Zealand Journal of Geology & Geophysics 33(1): 89-109   [1990]

The stratigraphic relationships and distribution of 36 named late Quaternary (less than 50 000 yr B.P.) silicic tephra formations, erupted from 4 volcanic centres - Okataina, Taupo, Maroa, and Tuhua (Mayor Island) - are presented. The stratigraphy and status of several other named late Quaternary tephras are also discussed. This compilation brings together all the data, currently scattered through many publications, to make tephrostratigraphy more accessible and more easily used. The nomenclature of tephra formations is discussed and some rationalisations are suggested. The term "tephrology" is suggested as an appropriate title for the field of tephra studies. The deletion of grain-size (ash, lapilli), shape (breccia), and lithologic (pumice) terms from all formation names is recommended, as is standardisation on a "Tephra Formation" format. Several tephra layers not previously formally named, or without designated type sections, are defined. The dominant ferromagnesian mineral assemblage of each tephra formation has been compiled as an aid to tephra identification. All available radiocarbon ages (384) on each tephra formation are presented, and each age is assessed for reliability in dating the eruption of that tephra. The standard-deviation weighted mean age of the reliable ages has been determined as the best current estimate of the age of each tephra. At least 10 tephra formations have no reliable ages, and efforts should be made to date these.

Keywords tephra formation; nomenclature; stratigraphy; mineralogy; C-14 ages; pyroclastics; volume

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A New Zealand regional holocene eustatic sea‑level curve and its application to determination of vertical tectonic movements

JEREMY G. GIBB

Royal Society of New Zealand Bulletin 24: 377-395  [1986]

Rates of vertical tectonic movements on the coast are determined by comparing displaced heights of paleosea‑level indicators with their eustatic sea‑levels. For this purpose, a New Zealand regional Holocene eustatic sea‑level curve, based on 82 radiocarbon dated sea‑level indicators sampled from eight very low uplift, or downdrop, sites once sheltered from the open sea is presented. The estuaries of Blueskin Bay (10 dates) and Weiti River (18 dates) are adopted as zero‑datums for the curve. Tectonic and eustatic effects are separated from each of the other six sites by obtaining the best fit of data from each site with the datum values, thus yielding tectonic rates for the past 10 ka (10,000 years B.P.) ranging from ‑ 0. 05 +/‑ 0. 01 m/ka to 0.30 +/‑ 0.04 m/ka. Eustatic sea‑level rose from ‑ 33.5 +/­2.5 in below present sea‑level at 10 ka with stillstands occurring at ‑ 24.0 +/‑ 2.9 in at 9.2 to 8.4 ka, and at ‑ 9.0 +/­2.8 in at 7.5 to 7.3 ka, the postglacial marine transgression culminating at the present sea‑level at 6. 5 +/‑ 0. 1 ka. During the last 6.5 ka, eustatic fluctuations on the order of a few decimetres have occurred with a regression minimum of about ‑ 0.4 in at 4.5 ka and a transgression maximum of about 0.5 in at 3.5 ka.

Comments This paper derives a Holocene sea-level curve for New Zealand based on radiocarbon-dated sites in areas of minimum uplift.

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The New Zealand Meteorological Service – the beginnings 1861-1927

J. F. de LISLE

Royal Society of New Zealand Bulletin 21: 17-24  [1984]

Comment A historical account of the New Zealand Meteorological Service up to 1927.

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Ironsand in continental shelf sediments off western New Zealand ‑ a synopsis

LIONEL CARTER

New Zealand Journal of Geology & Geophysics 23: 455-468  [1980]

The ironsand component (ilmenite, titanomagnetite, and/or magnetite) of surficial sediments on New Zealand's western continental shelf is highest on the inner‑middle shelf between Auckland and Taranaki where the mean concentration is x = 3.85% by weight. Sediments off Westland and Nelson contain only x = 0.17% ironsand. The subsurface distribution of ironsand, as revealed in piston cores, resembles that at the surface except that subsurface concentrations are markedly lower (e.g., x = 0.77% for Auckland-Taranaki).

Textural and compositional data from the Auckland‑Taranaki shelf suggest ironsand was originally concentrated under littoral conditions during the Holocene transgression and was dispersed north and southeast of the main primary source, the Egmont volcanics. The ironsand and host sediment are now approaching equilibrium with the modem hydraulic regime of waves and storm-induced currents and, therefore, are regarded as palimpsest.

Any ironsand concentrated on the Westland-Nelson shelf during a lower stand of sealevel is now covered by ironsand­-poor modem sediment; the Auckland‑Taranaki shelf has a far lower modern sediment supply and, thus, the ironsand has remained exposed.

Keywords offshore; economic geology; west New Zealand coast; ironsand; sedimentation; continental shelf; mineral resources; mineral deposits

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An uplift map for the South Island of New Zealand, and a model for uplift of the Southern Alps 

H. W. WELLMAN

Royal Society of New Zealand Bulletin 18: 13-20  [1979]

An uplift map for the South Island of New Zealand shows that the dominant uplift is along the Southern Alps. For the northwest side, the uplift rates arc summarized in a table. The maximum rate is about 17 mm/y and takes place, not on the upthrown side of the fault, but ‑ because of fault drag ‑ on an anticlinal axis some 5 km to the southeast.

Rates for the southern part of the southeast side are from the tilt of stranded shorelines in five glacial lakes. At the downstream end of the lakes, about 70 km from the Alpine Fault, the rate is 0.5 mm/y. The rate increases exponentially upstream, doubling for each 6 km, and reaches 2 mm/y. The uplift contours are interpolated from the 2 ‑10 mm/y values.

A deep vertical section normal to the trace of the Alpine Fault defines the uplift model. At river level, the fault dips steeply southeast, flattening with depth to become horizontal at about 30 km. The 30 km depth assumes the narrowing rate equal to the maximum uplift rate and that in the section, the area of narrowing equals the area of uplift; it agrees well with the 32 km derived from seismic S to P conversion. The steeply‑dipping schist‑greywacke section southeast of the fault trace is thought to be a once‑horizontal section that was rotated while being uplifted around the curved surface of the plane of the Alpine Fault.

In the model there is obduction, uplift, and hence erosion for the crust. An anti‑fault is postulated to subduct the upper mantle.

Comment This paper presents an uplift map for the South Island, based on a variety of geological evidence. In later years it has been used as a working model to test alternative hypotheses derived from geophysical evidence.

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Motion of the New Zealand Alpine Fault Deduced from the Pattern of Sea‑floor Spreading

D. A. CHRISTOFFEL

Royal Society of New Zealand Bulletin 9: 25-30  [1971]

The relative motion along the New Zealand Alpine Fault is computed from measurements of the pattern of sea‑floor spreading in the South Indian and South Pacific Oceans in terms of a model based on a modification of Le Pichon's plate tectonics (Le Pichon, 1968), and is found to have averaged 5.8cm/year over the past 10 million years. Morpho!ogically, the reconstructed Macquarie Ridge acquires certain characteristics of an island are system.

A second model, based on the assumption that the Alpine Fault and the Macquarie Ridge form an almost continuous transform fault, gives a computed average relative movement along the Alpine Fault of 4.2cm/ year.

Both models predict that the Alpine Fault has been active in its present form since the Middle Miocene and do not conflict with any known geological data.

Comment This was one of the first papers to use sea-floor spreading data to estimate plate movements in the south Indian and south Pacific oceans. It indicated a high rate of movement across the Alpine Fault over the last ten million years, and helped persuade New Zealand earth scientists that transcurrent movement on the Alpine Fault was late Cenozoic rather than much older.

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Notes on the Geology and Archeology of the Martins Bay District

H. W. WELLMAN and A. T. WILSON

New Zealand Journal of Geology & Geophysics 7(4): 702-21  [1964]

The Martins Bay district, 12 miles north‑east of Milford Sound, includes part of the southern end of the Alpine Fault. North‑west of the fault thermally metamorphosed greywacke and argillite is correlated with the Waiuta Group and thought to be Precambrian in age. From Milford Sound north for 6 miles a Wedge of marble and carbonaceous argillite (Kaipo Formation) with thick bands of pyritised granite lies between the fault and the Waiuta Group, and is thought to be the faulted north‑eastern extension ‑ of the Ordovician rocks of southern Fiordland. Fiordland gneiss lies to the south‑east of the fault. A coastal strip of Tertiary rocks without diagnostic fossils is correlated with rocks of the Paringa district. The Penguin Rock Breccia thought to have been produced by volcanic eruptions, is the oldest. The Otitia Formation rests unconformably on the Waiuta Formation and on the Penguin Rock Breccia, consists largely of limestone, and is considered to be Oligocene. The Tititira Formation is faulted against the Otitia Formation, consists largely of redeposited sediments, and is considered to be Miocene.

Moraine from an early ice advance (Piedmont Moraine) extends as a flattish sheet over the coastal uplands, and terrininal moraines from the last main ice advance mark the limit of sharp glacial features at about 3 miles from the coast in the main valleys. Other glacial advances are poorly represented. Sediments near sea level near the mouth of Lake McKerrow, probably deposited during the rise in sea level at the end of the Last Glaciation, contain a fairly large molluscan fauna similar to that Of the present day, and are capped by a terrace that represents a sea level about 15 ft higher than that of the present day. Maori occupation material on the coast, representing an extremely small population, can be stratigraphically related to dune advances. At least two periods of occupation and three dune advances are recognised.

The Alpine Fault is a straight line marked by many topographic irregularities that appear to have been caused by pure dextral movement. About 8 miles of dextral displacement has probably taken place since the Piedmont Glaciation, and about 800 ft since the last main glacial advance.

Comment Wellman revisited the southern end of the Alpine Fault thirty years after he first recognised and described the fault. Since the 1950s he had recognised that there was considerable evidence for repeated late Quaternary transcurrent movement, and in this paper he inferred that the whole of the 300 mile offset could have taken place within the last 19 million years.

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The Alpine Fault

R. P. SUGGATE

Transactions of the Royal Society of New Zealand (Geology) 2(7): 105-29 [1963]

Information on the Alpine Fault, scattered through a great deal of literature, is reviewed. The fault, which is steeply dipping, is continuous from Cook Strait to Milford Sound, and extends south‑west off the Fiordland coast. It is presumed to pass through the North Island, the most probable line being north from Feilding, passing between the Rimutaka Mountains and the Kaweka Range, and thence to the coast west of Whakatane. The 300‑mile horizontal shift was largely completed in the Rangitata Orogeny (late Jurassic and early Cretaceous). During the Kaikoura Orogeny (late Tertiary and Quaternary), vertical uplift in the South Island may have amounted to at least 60,000 feet in central Westland, where the amount of horizontal movement seems to have been about the same.

Comment Although Harold Wellman first proposed a 300-mile transcurrent movement on the Alpine Fault at meetings in 1948-49, he never documented this widely discussed this widely discussed hypothesis. In a presidential address to the Geological Society of New Zealand in 1962, Pat Suggate presented this summary of knowledge on the Alpine Fault. At the time he argued that transcurrent movement took place mainly in the Rangitata Orogeny (late Jurassic to early Cretaceous), and that late Cenozoic movement was predominantly vertical.

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Coastal surface currents around New Zealand

J. W. BRODIE

New Zealand Journal of Geology & Geophysics 3(2): 235-52  [1960]

Recoveries of drift cards from releases made off the New Zealand coast in the twelve months preceding July 1954 demonstrate the existence of a coastal circulation, dependent on the surrounding oceanic currents and the topography for its basic pattern.

Comment A pioneering paper that established the major surface coastal circulation patterns around New Zealand.

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Soda-Metasomatised Argillites Associated with the Nelson Ultramafic Belt

J. J. REED

New Zealand Journal of Geology & Geophysics 2(5): 905-15  [1959]

Petrographic, chemical, and X‑ray study of indurated argillites associated with the Nelson ultramafic belt has indicated marked soda‑metasomatism. The hardness of the argillites is due largely to albitisation, but additional toughness has been imparted, particularly in those specimens used by the Maoris for tool manufacture, by a felted crystallisation of minute tremolitic fibres. Hochstetter's hypothesis that the indurated argillites were included and altered by the ultramafites appears the most probable and is supported by comparison of the amphibolitisation of the argillites with nephritisation.

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Chemical and Modal Composition of Dunite from Dun Mountain, Nelson

J. J. REED

New Zealand Journal of Geology & Geophysics 2(5): 916-19  [1959]

A chemical and modal analysis is presented of the type dunite discovered by F. von Hochstetter on Dun, Mountain, Nelson.

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Bouger Anomaly Map of New Zealand

E. I. ROBERTSON and W. I. REILLY

New Zealand Journal of Geology & Geophysics 1(3): 560-64  [1958]

The Bouguer map of New Zealand exhibits two major negative gravity anomalies. The Rangitikei‑Waiapu Anomaly, which intersects the axial ranges of the North Island, indicates a crustal downwarp which is not in isostatic equilibrium. This anomaly is closely parallel to the zone of intense seismicity, to the Taupo‑White Island volcanic belt, to the Kaimanawa‑Huiarau‑Raukumara Ranges, to the thick Upper Pliocene sediments, and to the Hikurangi Trench: and it appears to be an expression of an active tectonic belt related to the Tonga‑Kermadec‑Hikurangi Trenches. The Rimutaka‑Ruahine axial ranges are apparently not underlain by mountain roots.

The Alpine Anomaly in the South Island is considered to be the gravitational expression of the crustal roots of the Southern Alps and the mountains south‑west of Blenheim; the magnitude of the anomaly suggests that this region is approximately in isostatic equilibrium.

Comment The first national gravity map of New Zealand, based on 12,000 measurements throughout the country, which established the major features of the gravity pattern in New Zealand.

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Uranium mineralisation in the Hawks Crag Breccia of the Lower Buller Gorge Region, South Island, New Zealand

A. C. BECK, J. J. REED, and R. W. WILLETT

New Zealand Journal of Geology & Geophysics 1(3): 432-50  [1958]

Bedded uraniferous deposits have been discovered in the middle (?) Cretaceous Hawks Crag Breccia formation of the lower Buller Gorge region of the South Island of New Zealand, and in three areas to the south (Bullock Creek, Waitahu River, and Fox River mouth). The characteristic feature in all the areas is the restriction of the mineralization to the arkosic facies of the Hawks Crag Breccia.

On the north side of the Buller Gorge, at least ten uraniferous horizons are known, ranging in width from a few inches to several feet. Within each horizon the mineralization is patchy. The main primary 'uranium mineral is coffinite which has been introduced along with pyrite, carbonate (largely ferroan dolomite), and red hematite staining of the elastic feldspar. Secondary uranium minerals are generally inconspicuous. The deposits are considered to result from low ­temperature mineralization by epigenetic solutions, but it is still uncertain whether the uranium originated from dispersed sources in the arkosic sediments or was introduced in hypogene solutions from lamprophyres and porphyries.

Minor uranium concentrations are associated with a poryphyry dyke in Hawks Crag Breccia and with quartz veinlets and lodes in granite‑gneiss and Greenland sediments.

A comparison is made between mineralization in the Buller Gorge and on the Colorado Plateau.

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The Nature and Alteration of Some Triassic Sediments From  Southland, New Zealand

D. S. COOMBS

Transactions of the Royal Society of New Zealand 82(1): 65-109  [1954]

Triassic greywackes and tuffs have been examined more especially from the northern part of the Taringatura Survey District, where there is a succession approximately 28,000 feet thick. A progressive increase in the degree of albitization of detrital plagioclase towards the base has been recognized and there are concurrent increases in the amounts of secondary lime‑bearing minerals, Abundant beds of glassy tuffs were converted during diagenesis to zeolite rocks consisting mainly of heulandite or analcime, and these minerals are still found in the upper parts of the succession. Towards the base, analcime is now represented only by pseudomorphs and most masses of devitrified tuffs have been converted to laumontite rock. Metasomatic effects accompany these changes and in extreme cases quaxtz‑albite‑adularia‑pumpellyite metasomatites are developed. Chemical and spectrographic analyses are presented to show the course of the changes. The metamorphism is low‑temperature hydrothermal in its effects although unrelated to igneous activity. It took place progressively with increasing temperature under increasing load and was made possible by vast quantities of water stored in volcanic glass and in zeolites of early formation.

Comment This classic paper documented the mineralogical changes with burial of a thick sequence of tuffs and volcanogenic sediments in the Taringatura Hills, including the progressive changes from glassy tuffs to zeolite minerals. This sequence was subsequently the basis on which the Zeolite Facies of low-grade burial metamorphism was proposed.

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Data for the Study of Recent and Late Pleistocene Faulting in the South Island of New Zealand

H. W. WELLMAN

New Zealand Journal of Science & Technology B34(4): 270-88   [1953]

The basic geological information for the study of Recent and late Pleistocene faulting in the South Island of New Zealand is summarized in a table and illustrated by a map.

Comment During 1951 Harold Wellman scanned all the available aerial photographs of the South Island, and identified active fault traces. All his observations are listed in tables, and this has formed the basis for later studies of active faults. The map on p. 271 is the first map to accurately show the location of major faults in the South Island.

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The Alpine Fault in Detail: River Terrace Displacement at Maruia River

H. W. WELLMAN

New Zealand Journal of Science & Technology B33(5): 409-414  [1952]

From the Alps of south Nelson, Maruia River flows west within a wide glacial valley with numerous post‑glacial river terraces to cross the Alpine Fault almost at right‑angles. Recent movement on the line of the fault has interrupted. the continuity of these terraces. Vertical movement, terrace top displacement, is upward on the Alpine side of the fault; horizontal movement, terrace front displacement, is in a clockwise direction. On the south side of the river, vertical displacement is greater in the older and higher terraces than in the younger an& lower ones, the oldest terrace being displaced 12 feet. On the north side of the river, the younger terraces have not been preserved. The maximum displacement of the oldest terrace is 70 feet. Horizontal movement is probable on both sides of the river, but can be proved only in the open country on the south side, where the Alpine side of the three highest terraces has moved 33 feet south‑west. This direction of movement (clockwise) is in the same sense as the horizontal displacement previously suggested at the Alpine Fault in South Westland. Younger terraces are not displaced horizontally.

Comment This paper was the first time that repeated horizontal and vertical movement offsetting young river terraces was recognised on the Alpine Fault. It inspired Wellman to search for other localities where repeated offsets could be recognised, and led to his work mapping and analysing active faults throughout the South Island.

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The Geology of the West Coast from Abut Head to Milford Sound ‑ Part 1.

H. W. WELLMAN and R. W. WILLETT

Transactions of the Royal Society of New Zealand 71(4): 282-306  [1942]

A map is presented showing the geology of the West Coast from Abut Head to Milford Sound. The geology is described, the Tertiary beds being discussed in greater detail than the older rocks. Attention is drawn to a major fault that extends along the west of the Southern Alps and to the direct and indirect effect of this fault on the physiography. A late Tertiary peneplain is considered to extend along the west side of the Alps and the relation between this peneplain and the present drainage is discussed. An interpretation of the geological history is presented, and it is considered that the Alps since the Hokonui orogeny have been twice base‑levelled and re‑elevated. The description of the Pleistocene deposits will be presented in a later paper.

Comment This paper describes the geological results of a major expedition in South Westland when the Alpine Fault was first recognised. The criteria for mapping the fault were outlined, and the northern extent of the Alpine Fault was inferred from interpretation of existing geological maps.

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Notes on some volcanic rocks of the North Island of New Zealand

P. MARSHALL

New Zealand Journal of Science & Technology 13: 198-202  [1932]

Comment In this short paper, Patrick Marshall introduced the term Ignimbrite for the widespread pyroclastic rocks of the central North Island and gives a preliminary description of a new mineral, Tuhualite, from Mayor Island. Later papers gave more detailed descriptions.

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The Geomorphology of the Coastal District of South-Western Wellington

C.A. COTTON

Transactions of the New Zealand Institute 50: 212-22  [1917]

Comment This paper is typical of many produced by Charles Cotton from 1912 to 1955 - a careful description of the geomorphology, illustrated by sketches and block diagrams illustrating the evolution of the landscape. Cotton was a major influence on New Zealand geologists by demonstrating how the landscape reflected the underlying geology and tectonic features.

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The Mokoia Aerolite

G. A. MARRINER

Transactions of the New Zealand Institute XLII: 176-85  [1910]

Comment A detailed account of the fall of Mokoia meteorite on the 26th November 1908. The paper also includes a description of other two other meteorites that had been previously identified in New Zealand.

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Origin of the Loess Deposits of the Timaru Plateau

J. HARDCASTLE

Transactions of the New Zealand Institute 22: 406-14  [1890]

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On the Timaru Loess as a Climate Register

J. HARDCASTLE

Transactions of the New Zealand Institute 23: 324-32  [1891]

Comment These two papers present a very perceptive interpretation of loess deposits in the Timaru area. John Hardcastle recognised that the loess deposits were windblown dust, formed during glacial periods, and went on to link the layers of loess to changing climate. This was many years ahead of interpretations by European and Amercian scientists, and John Hardcastle is now recognised as a pioneer in international loess studies.

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On Mining in New Zealand

JAMES HECTOR

Transactions of the New Zealand Institute 2: 361-84  [1870]

Comment This is one of the first reviews of economic geology and mining in New Zealand, prepared only four years after Hector had taken up his position as the first Director of the New Zealand Geological Survey. It gives an interesting view of how the mining potential of New Zealand was regarded in 1870 while the more remote parts of the country were still being explored.

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The Alpine Fault from Lake McKerrow to Milford Sound

R.H. CLARK & H.W. WELLMAN

New Zealand Journal of Geology & Geophysics 2(3): 590-601  [1959]

The Alpine Fault intersects the west coast of the South Island of New Zealand about four miles north of Dale Point at the entrance to Milford Sound; moraine on the west of the fault has been faulted against Fiordland Gneiss on the cast. A well defined fault trace was followed from the air from the south side of Lake McKerrow through the cast side of a huge eroded crush zone in the Kaipo River to the contact between moraine and gneiss at Stripe Point. The fault trace interrupts topography that probably formed during the last glaciation. The major displacement is dextral transcurrent adid similar in direction and amount to that on the fault in the north, the valley of Kaipo River being displaced about a mile. The Alpine Fault is thus a major transcurrent fault at its southern limit on land with essentially the same character as along the western side of the Alps to the north.

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Beach gravels and sands

P. MARSHALL

Transactions of the New Zealand Institute 60: 324-65   [1929]

Comment Patrick Marshall carried out experiments on the wearing of gravels in a rotating drum over several years in the late 1920s. In this paper he summarises the results of the laboratory work and compared his results to the observed rounding of gravels on the beaches near Napier. He also describes the nature of sand from different types of beaches around New Zealand as well as offshore samples dredged from near Napier.

Although similar work had been taken overseas, this is one of the first examples in the world of the integration of laboratory experiments and field observations on the material that makes up beaches.

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The hot springs and hydrothermal eruptions of Waiotapu

E.F. LLOYD

New Zealand Journal of Geology & Geophysics 2(1): 141-76  [1959]

On the basis of chemical composition, the waters of hot springs of the Waiotapu thermal area have been divided into four classes: acid sulphate waters, sulphate‑chloride waters, chloride waters, and bicarbonate‑chloride waters. The origin of the waters and the relationship of the hot springs to geological features is discussed. The natural heat flow of the Waiotapu thermal area has been estimated as 302,000 Kcal/sec above 15o C.

About 900 years ago hydrothermal eruptions took place throughout the Waiotapu district, and these are discussed especially in relation to the close association of present thermal activity with craters formed, during these outbursts, and the effects of the volcanicity on the hydrothermal system. A possible mechanism for triggering these eruptions is advanced.

Comment This is one of the first detailed descriptions of a thermal field in New Zealand, integrating the results of geology and chemistry as well as historic information. Detailed mapping showed the presence of hydrothermal eruption breccias, and carbon-14 dating allowed them to be dated.

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Landslides and allied features in the Dunedin district in relation to geological structure, topography, and engineering

W.N. BENSON

Transactions of the Royal Society of New Zealand 70(3): 249-63  [1940]

Comment Through his detailed geological mapping of the Dunedin district, Professor Benson became aware of the wide extend of landsliding in the region. This is one of the first papers in the world to describe a variety of landslide features in layered soft rocks and their close connection with geology.

The Abbotsford landslide of 1 August 1979 was a shock to local residents, but it was subsequently realised that Benson had described similar features leading to landsliding almost 40 years earlier.

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Magmatic eruption of White Island volcano, New Zealand, December 1976-April 1977

R.H. CLARK; J.W. COLE; I.A. NAIRN & C.P. WOOD

New Zealand Journal of Geology & Geophysics 22(2): 175-90  [1979]

White Island volcano erupted fresh andesite during March 1977, in the first emission of new lava bombs and blocks recorded in historic time. Preliminary analytical data indicate that the new lava differs petrographically and chemically from all other analysed White Island lavas. The eruption commenced with ejection of accessory ash derived from crater floor debris, overlying a shallow magma intrusion which has been causing inflation of the crater floor since 1973.

Comment White Island emits ash almost continuously, but petrographic study shows that the dust component is largely hydrothermally-altered andesite. Eruptions in early 1977 produced the first fresh magma recorded in historic time.

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Tectonic and earthquake risk zoning

R.H. CLARK; R.R. DIBBLE; H.E. FYFE; G.J. LENSEN; R.P. SUGGATE

Journal of the Royal Society of New Zealand (General Series)1(10): 113-26  [1965]

Quaternary tectonic deformation in New Zealand shows a north‑cast trend, and this is also shown by historic deformation and earthquakes. A study of Quaternary deformation shows that zones of relative frequency of tectonic movement can be inferred and related to a common median axis. Where tectonic activity is most frequent, destructive earthquakes are expected to be most frequent. Conversely, where tectonic activity is least frequent, destructive earthquakes are expected to be least frequent. With this as a basis, together with a knowledge of the distances to which destructive effects extend from earthquakes of particular magnitudes, zones of earthquake risk are suggested. These are zones of relative frequency of destruction from earthquakes, not of absolute liability to destruction; the boundaries are necessarily somewhat arbitrary as each grades into the next.

Comment This paper was the first attempt to show that some parts of New Zealand are more susceptible to earthquakes than other, based largely on geological evidence. It was strongly opposed by a number of geophysicists, who argued that the conclusions were not supported by historical seismicity.

In 1965 it was believed that seismicity was low in eastern Otago. Subsequent research has shown that there is considerable evidence for active faults in parts of Otago.

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The fossil plains of north Otago

C.A. COTTON

Transactions of the New Zealand Institute 49: 429-32  [1917]

Comment Charles Cotton was a pioneer in applying the study of landforms to the interpretation. He recognised that the widespread peneplain surfaces in Otago were ancient features that had been exhumed – which he called “fossil plains” – and showed that they had offset by major faults.

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A bathymetric survey of the Waimangu thermal lakes

R.F. KEAM

New Zealand Oceanographic Institute Records 4(7): 55-69   [1980]

Techniques and equipment used for determining the bathymetry of hot lakelets in the Waimangu thermal area are described.

Comment Between 1975 and 1978 R.F. Keam undertook detailed bathymetric surveys of two small lakes in the Waimangu thermal area. The temperature was mainly in the range 50°-60°C, but temperatures as high as 74°C were locally encountered. This paper gives an account of the issues involved in surveying hot lakes, and describes the Maji Moto, a wooden boat specially constructed for this project.

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