Review of the Notocenozoic, or Cretaceo-Tertiary of New Zealand
[Presented in condensed form as a lecture at Oxford University, November 25, 1952, and, as the Hudson Lecture to the Wellington Branch, July 28, 1954; receive by the Editor; July 15, 1954.]
The name “Notocene” was suggested by J. A. Thomson for a stretch of unbroken sedimentation in the New Zealand region following a post-Hokonui emergence. Though this name has not come into general use, the only valid objection to it that has been raised is that it has been applied to an era rather than to a period analogous with Eocene, etc. Then can be no such objection to the use of “Notocenozoic”.
The unity of such an era—unbroken by regional withdrawal of the sea—is now generally accepted as a tact; and the era must perhaps be thought of as still continuing, seeing that emergence of part of the area of marine sedimentation is still in progress. If so, the name “Notopleistocene” suggested by Thomson for post-Notocenozoic time is of no value.
A review is presented of the history of subdivision of the New Zealand Upper Cretaceous-Tertiary sequence into series and stages, with reconciliation of formerly opposed schools of thought on the question of the presence of strong unconformities within the sequence, these having been found to be confined (along with most minor breaks) to crests and flanks of anticlinal belts with a persistent tendency to rise intermittently. Such local gaps in the succession having been recognized. the question has arisen of the desirability or otherwise of making use of them to subdivide the sequence as a whole into systems or series.
The eventual adoption of a subdivision into series which are groups of stages established on strictly paleontological ground is reviewed, and also the demonstration by means of similar evidence of the presence of passage beds from the Cretaceous to the Tertiary.
|The Notocenozoic era||1073|
|Upper Cretaceous–Tertiary classification||1074|
|Cretaceous stages recognized by Thompson and others||1077|
|Section at Amu [ unclear: ] Bluff||1082|
|Mount Grey section||1084|
|Malvern Hills section||1085|
|Shag Point section||1085|
|Pu [ unclear: ] lpauan in the North Island||1086|
|The Amu [ unclear: ] Limestone formation perhaps Wangaloan in part||1088|
|The “Oamar [ unclear: ] u System ”||1091|
|Daunev [ unclear: ] ike Series||1091|
|Arnold, London, and Pareora Series||1092|
|Age of Island Sandstone and Kaiata Mudstone formations||1095|
|“Ototari [ unclear: ] an”||1097|
|The Notocenozoic transgression in relation to limestone formation||1099|
|Stability of the region in the early Tertiary||1099|
|The East Coast geosyncline||1101|
|The “Oamar [ unclear: ] u System” (continued)||1105|
|Restricted occurrence the Pareora Serise||1119|
|End ot the “Oamaru “period||1110|
|Regional distribution of the Southland Series||1113|
|Hawer [ unclear: ] a Series||1120|
In contrast with an intra–Cretaceous continental episode, which followed the post-Hokonui orogeny, it is clear that there was no general emergence of the New Zealand region between the Cretaceous and Eocene. On the contrary, a continuous sequence of marine Cretaceous–Eoeene passage beds, long sought for, is now known. That this is firmly established is due to the paleontological skill of the late Dr. H. J. Finlay.
A transgression, which began in the early Upper Cretaceous, extended more and more widely from time to time; and in many districts marine deposition went on continuously or almost continuously (with local breaks only) throughout the Tertiary era. Unconformities, some of them strongly angular (Ongley, 1924), and also such disconformities as have been discovered are for the most part of limited lateral extent, indicating only local emergence and erosion. Naturally, the areas affected by such local upheaval and emergence varied, but apparently even the most extensive emergences failed to develop regionally. There seems to be, for example, an Upper Eocene gap in the sequence in the northern part of
the North Island, especially marked in the far north, where early Tertiary orogeny affecting late Cretaceous and Paleocene strata has been reported (Bartrnm and Turner, 1928; 1934; Battey, 1952), but open-sea sedimentation went on uninterruptedly in southern districts during that time.
In no district, as might be expected, has an unbroken sequence been found such as would indicate complete local continuity of sedimentation throughout its whole area; in most sections there are some non-sequences, diastems, or dis-conformities, some of them detectable only after study of paleontological evidence. This has not always been available, owing to poverty of macrofannas in many sections, but in the majority of eases foraminiferal evidence has made up for this deficiency. There are certain gaps that cannot be explained by emergence, but seem due rather to cessation of sedimentation for quite long periods. Some at least of these must have been caused by pauses in sea-floor subsidence, during which infilling above the level of wave base does not go on, the sediment being by-passed and deposited elsewhere. Such a condition might endure for millions of years in a region as stable as parts of the New Zealand area appear to have been throughout late Cretaceous and early Tertiary times.
Notwithstanding gaps of this kind in the sedimentary record, and though it is unlikely that a complete section exists at any one place (in the area that, is now above the sea), it was long ago suspected that when evidence from many scattered localities was pieced together a record would be available of beds of every age from early Upper Cretaceous to Pliocene. With the help of micro-paleontology this goal is in sight; and it now seems even that, the record continues through Pleistocene into Recent time.
The Notocenozoic Era
It was for such a stretch of unbroken sedimentation, following the post-Hokonui emergence, or continental period, that the name Notocene was proposed and used by Thomson (1917, p. 408). Since that time it has been applied to some extent by New Zealand geologists, though it is not in general use and has never been officially approved by the Geological Survey. As defined by its originator it referred to a period (or era) which lie supposed to have been brought to an end by another emergence of the whole New Zealand region during the Kaikoura orogeny; but it is clear now that this was a mistake, and that this (Pliocene-Pleistocene) orogeny has not only been of considerable duration, but continues in some districts to the present day, so that end members (of Pleistocene age and younger) of the “Notocene” sequence are still emerging (Te Punga, 1953).
Objections to the word “Notocene “have militated against its general adoption; but the underlying idea has been found generally acceptable except in so far as it has been misunderstood to imply an absence of even local breaks (large and small disconformities and diastems) in the sequence and to deny the presence in some districts of strong angular unconformities within the group.
A name “Notopleistocene”. which Thomson proposed for the period following the Kaikoura earth movements, whatever the date of these, and continuing to the present day, has been mistakenly regarded as a synonym for Quaternary (Morgan, 1926, p. 277), and has been little used To treat this period as necessarily beginning at the dawn of the Pleistocene is obviously incorrect and misleading, as it is clearly either longer or shorter than the Quaternary, let the general question of Pliocene–Pleistocene boundary be settled as it will, There need, however,
be no question of attempting to rehabilitate “Notopleistocene” now, for, if there has been no regional anorogenic interlude since deformation began in late Tertiary times, and if marine sediments which are conformably a part of the Upper Cretaceous–Pleistocene sequence are still emerging, then, it could be claimed, the hypothetical Notopleistocene has not yet begun. Even if, on the other hand, earth movements now going on are part of a new post-Kaikoura orogeny (movement having been renewed after a period of rest), the fact remains that the true, or restricted, Kaikbura movements did not everywhere introduce an angular-unconformable gap into the marine succession, so that the break proposed by Thomson between Notoeene and Notopleistocene is invalidated. The most recently emerged marine beds, regarded as of sub-Recent to Recent age, cannot be thus separated from the “Castlecliffian of Wanganui,” which Thomson (1917) specifically included in his Notocene.
Terms such as “Recent”. “Pleistocene”, and “Quaternary” are of course equally 'ague, or even meaningless, when applied in New Zealand, more especially if, as is the case also in some other parts of the world that have been glaciated, there are few, and those only very imperfect, records of a succession of glacierizations extending far back into Pleistocene time—other, that is to say, than certain indications of fluctuation of temperature found in the shallow-water faunas of the Castlecliffian (now regarded as Pleistocene, but formerly as Upper Pliocene) and even in the Nukumaruan, formerly correlated with Middle Pliocene (Fleming, 1953, p. 301).
Unlike the perhaps non-existent “Notopleistocene” interval (as strictly defined) the vast “Notocene” interval is real and has unity; but it is so large a unit that it is best treated as an era, and may, therefore, be termed the Notocenozoic (Cotton, 1954). It in thus possible to define a major transgression and cycle of sedimentation in the New Zealand region—one comparable to the Hokonui era whish preceded it, and even better defined. Lillie (1951, p. 219) has stated the position as follows: “In New Zealand any geologist who attempted on purely local evidence a division of strata into Primary, Secondary, and Tertiary would be inclined to define his … Secondary as including perhaps the lower Cretaceous, and his new Tertiary system [the Notocenozoie] would perforce include some upper Cretaceous rocks and perhaps even some Pleistocene.” It was such a “new Tertiary” that Thomson proposed to call Notocene. The only valid objection to the use of “Notocene” is that it has been applied as the name of an era, not a period analogous with Eogene. Oligocene, etc. There can be no such objection to the use of “Notocenozoic” (analogous with “Cenozoic”) to name the era Lillie has referred to as the “new Tertiary”.
Upper Cretaceous–Tartiary Classification
Before listing divisions of the Notocenozoic it is necessaiy to review briefly some alternative views of New Zealand Cretaceous and Tertiary classification (Table I).
That of Hector (1886), embodying the official view of the nineteenth century Geological Survey, was not in its general outline far from correct (in the light. of information becoming available as results of field studies now in progress are made public). No great gaps were believed to break the succession of foramtions. The main divisions recognized were :
Lower Greensand [with age significance as in the Cretaceous of England];
“Cretaceo-Tertiary”; Upper Eocene; Lower Miocene [= Oligoeene]; Upper Miocene; Pliocene. These were believed to follow one another almost if not quite conformably. Much confusion was introduced, however, in the lower part of the
[The section below cannot be correctly rendered as it contains complex formatting. See the image of the page for a more accurate rendering.]
|Late Nineteenth Century.|
|Hecton||Hutton||Thomson (1916; 1917)||Geological Survey (1948)|
|Wanganui (= Pliocene)||Wanganui|
|Pareora (= Miocene)||Awamoan||Tertiary||Southland||23 stages of Paleocene and Tertiary|
|Oamar [ unclear: ] n (= Oligocene)||Ototaran|
|Waipara (= Upper Cretaceous)||Pur [ unclear: ] ipauan||Mata (3 Stages)|
succession by mistaken correlation, and especially by the lumping together of fossil faunas from certain beds of Cretaceous and others of Tertiary age that had been erroneously correlated on supposed stratigraphical and litholotgical grounds. It was in this way that the very famous “Cretaceo-Tertiary”, a mythical system,
was concocted. Its fauna was believed not to be intermediate in character between those of the Cretaceous and the Tertiary, such as might be expected in passage beds between series elsewhere separated by unconformity, but to contain a mixture of forms characteristic of Cretaceous and Tertiary.
The view of Hector's contemporary Hutton (1885)—which was quite irreconcilable with that of Hector—was that regional unconformities of large time value were recognizable, the greatest being one separating an Upper Cretaceous (Waipara) system from an Oligocene (Oamaru) system. A Miocene (Parcora) and a Pliocene (Wanganui) system were also separated. In the intervals between these Hutton believed he found evidence of strong regional emergence and erosion. Various other geologists (notably Park and Morgan) in the early decades of the present century have followed Hutton very closely.
The first suggestion of a hypothesis of continuity (without breaks of regional significance) in the succession came from Marshall. He was supported at first by Speight and Cotton (1911), but they were, apparently, unable to shut their eyes to evidence of the existence of locally developed unconformities, denial of which was an article of faith with Marshall, and so he was left to carry on the campaign alone. Not only did he refuse to accept any evidence of unconformities or disconformities, but his recognition of the existence of passage beds between Cretaceous and Tertiary was clouded by his rather grudging admission that the basal beds of the whole system might possibly be Cretaceous in age, an admission accompanied by a claim that their age could quite well be Eocene—a survival of a Cretaceous fauna into the Eocene being postulated as possible and attributable to isolaion of the New Zealand region. He wrote. “The earliest beds suggest a Cretaceous age, but the characteristic Cretaceous forms may have lingered on as a result of the isolation of the sea-basin in which the deposits were laid down” (Marshall, 1912b, pp. 197–8) His adoption of this view seems to show that he was still influenced by Hector's Cretaceo-Tertiary theory. Minimizing the Cretaceous “affinities”, and ignoring the accounts long previously published by McKay of a thick Cretaceous mudstone formation in the rather inaccessible Clarence Valley, probably regarding these as largely romantic, for he was slow to admit the validity of any of McKay's discoveries, Marshall telescoped the whole of the Notocenozoic, with the exception of the highest (Wanganui) series, into Huttor's Oamaru system, which he described as “Cainozoic. mostly early” (Marshall, 1912b, p. 188). It must be kept in mind that Marshall, together with the other geologists of his own and an earlier generation (with the exception of McKay), thought of the floor on which Tertiary sediments accumulated as a surface with strong relief surviving from the post-Hokonui orogeny. He allowed, further. for the occurrence of no earth movements other than regional, or epeiro-genic, subsidences and upheavals during his “Oamaru” period. Facies differences could be invoked to explain difficulties of correlation, and a too simple concept of a single cycle of sedimentation called for its culmination in a limestone facies at the maximum of submergence, or peak of the transgression. His correlation, based on this hypothesis, of all Notocenozoic limestones (except shelly Pliocene facies in the North Island) as Oligocene turns out, however, to be not far from correct, though later (1916), as a result of his identification of the fora-miniferal genus Amphistegina in many thin sections, he became convinced that the age of limestone formation was Miocene.
The fact, long recognized, that Notocenozoic sedimentation began at widely different times in different localities has recently attracted renewed attention (Suggate, 1950; Wellman, 1953). Suggate has shown that in the western and north-western districts of the South Island the basal formations, now termed the “quartzose coal measures”, as dated by fossiliferous marine strata immediately overlying them, overlap from Bortonian (equivalent to early or middle Eocene) in the south, near Greymouth, to Duntroonian (equivalent to early or middle Oligocene) in the north, near Cape Farewell, being of intermediate ages in intermediate localities (Fig. 1). Marshall (1912) explained such overlap found in various parts of New Zealand by his simple theory of transgression throughout a period of regional subsidence. Some explanation is required, however, that is based on a recognition of differential subsidence district by district, and from time to time, to allow of such delayed overlap consistently with recognition of the fact that the whole region had already been reduced to very small relief in the early Notocenozoic Hence the theory of “diastrophic provinces” sinking at different times so as to allow sedimentation and eventually marine transgression to take place over well-planed floors (Cotton, 1917; Thomson, 1917).
Cretaceous Stages Recognized by Thomson and Others
The subdivision by Thomson (1917) of the lower (i.e, Cretaceous) part of the Notocenozoic recognized three “stages”, Clarentian, Piripauan, and Kaitangatan. The “Clarentian”, though accepted as of stage rank until recently, is now treated by the Geological Survey as of higher rank, being called Clarence Series (Geol. Surv., 1948). The Piripauan remains a stage; while “Kaitangatan “has given place to Wangaloan as a stage name (Finlay and Marwick, 1937). More recently an additional stage, Teurian, has been recognized as of age intermediate between the Piripauan and Wangaloan; and the three stages Piripauan, Teurian and Wangaloan have been grouped as the Mata Series (Finlay and Marwick, 1937; Geol. Surv. 1948).
The type locality for the Clarence Series (early Upper Cretaceous) is in the tectonic Middle Clarence Valley, where it occupies a strip in the fault angle,
or asymmetric, fault-broken syncline, between the upheaved Kaikoura and Seaward Kaikoura Ranges, in eastern Marlborough; but it outcrops also in a similar (parallel) strip in the adjacent Awatere Valley syncline, or fault angle. In both of these localities thick sedimentary formations are elongated along northeasterly striking belts that dip north-westward to be cut off by great faults bounding the a adjoining ranges. Strata of a thick, largely mudstone formation forming the basal part of the strip in the Clarence Valley yield fossils which have been described by Woods (1917) and pronounced to indicate correlation with the Lower Utatur beds, of India.
Thomson (1919) has described the type (Clarence Valley) section in considerable detail. Resting with the strongest possible angular unconformity on the highly deformed (Hokonui) greywacke rocks of the Seaward Kaikoura Range a thick succession of beds referable to the Clarence Series (Fig. 2) dips northwestward and is followed by a remarkable formation of flint, or chert, beds of undetermined age and then by a white limestone (the Amuri Limestone), above which beds known locally as “grey marls” follow conformably, these being capped by a very coarse conglomerate derived partly from the more resistant of the underlying formations, present as large angular blocks, with admixture of well-rolled pebbles from the unconformably older Hokonui greywackes. With this (quite young, late-Tertiary) conglomerate the succession of beds in the Clarence section ends against the great reverse fault along the base of the Kaikoura Range. The structure had been described earlier by McKay and Hector and by Cotton (1913), all of whom recognized that the Notocenozoic formations, instead of being deposits in a fiord between pre-existing mountain ranges, as Hutton (and later Park, 1910) believed, occupied a recently formed tectonic depression partly synclinal and partly a fault angle.
Facies variation from this type marine section is found south-westward along the strike, where there are terrestrial beds, with plant remains, which Thomson regarded as correlatives of the basal part of the marine Clarence section.
North-west of the Kaikoura Range, in the Awatere Valley, where the Notocenozoic formations are preserved in another fault angle similar to that of the Clarence Valley, the Clarence Series consists largely of a thick accumulation of basic lavas and tuffs, the latter fossiliferous.
Text-Fig. 2.—Generalized section across the Middle Clarence Valley, Marlborough, showing stratigraphic relations and apparently great thickness of the Clarence Series. (But sec footnote p. 1079.)
In the type marine section, in the Middle Clarence Valley, there does not seem to be a physical break of any importance in the succession either within or above the Clarence Series. Though thick mudstone formations alternate with thinner
strata of sandstone, the latter appear to be lenticular and without sufficient lithological continuity to mark or to separate distinct horizons. No definite marker bands have been traced throughout the valley. Locally, in the type section, however, the sequence is as follows:—
|Sawpit Gully Mudstone||3,200 feet|
|Nidd Sandstone and Mudstone||550 feet.|
|Cover Creek Mudstone||2,000 feet|
|Wharf Gorge Sandstones||450 feet|
|Wharf Mudstone||1,500 feet.|
|Basal Conglomerate||250 feet|
[These thicknesses are maxima, and the total thickness of the series varies from 3,000 to 9,000 feet.]
Though fossils are found sparingly at various horizons, the paleontological work of Woods (1917) on these has not afforded a basis for subdivision of the series. Woods has referred the fauna throughout to the Lower Utatur (of India), which has a wide distribution in the Indo-Pacific region (Japan, California, Peru, India, Madagascar, South Africa), indicating extensive development of the “Cenomanian” transgression. It is regarded as Albian—perhaps Upper Albian or Albian-Cenomanian.*
The contention of Woods that only a single zone is represented is perhaps supported by the foraminiferal evidence, which is said to indicate no great difference in age between the lower and upper mudstones (Geological Survey, 1948, p. 18). Finlay (1948) reported a remarkable sameness in microfaunas up to within a few feet of the overlying flint beds, all resembling an Upper Albian microfauna in Texas.
On the other hand, however, a re-examination of the molluscan fossils described by Woods led Marwick (1934) to the conclusion that mudstone and sandstone strata of the type section range in age from Albian (the Wharf Mudstone) to Senonian (the Sawpit Gully Mudstone) (Table II); and Finlay and Marwick (1940) regarded the extent of the Clarence Epoch to be Albian–Coniacian (Lower Senonian). A Coniacian indicator is Gaudryceras subsacya, Woods's identification of this as G. sacya being amended to subsacya Marshall. The one belemnite of the Clarence fauna, which has been referred by Whitehouse to Dimitobelus, a genus restricted in Australia to Upper Albian, is not found throughout the section, but only in the lower part. The presence of the belemnite (originally identified by Woods as Belemnites superstes) in beds close to the base makes it unlikely that any part of the section is of Lower Albian or Aptian age.
The chief indicators, cited by Woods, of “Albian” (Lower Utatur) age were: Inoceramus concentricus, Turrilites circumtaeniatus, Gaudryceras sacya, several species of Trigonia, and species of Arca, Modiola, Spondylus, Pecten, Lima, Aucellina, Panope, and Thracia (The genus Aucellina is an indicator of early rather than late Cretaceous age.)
[Footnote] * Postscript: Evidence has been presented by Mr. H. W. Wellman at a meeting of the Geology Section of the Wellington Branch. R. S. S.Z., August 12, 1954, that there is probably repetition of the outcrops of some beds in the type section owing to the presence of strike faults. Thus the apparently great thickness of the series containing Upper Albian fossils in mudstone strata may be illusory and due to reduplication of a single mudstone formation.
[The section below cannot be correctly rendered as it contains complex formatting. See the image of the page for a more accurate rendering.]
|Sawpit Gully Mudstone||Senonian (with Gaudryceras sacya and Inoceramus concentricus poll [ unclear: ] ectus)|
|X [ unclear: ] idd Sandstone and Mudstone||Turonian (with Inoceramus bicorrugatus, Marwick)|
|Cover Greek Mudstone and Wharf Gorge Sandstone||Cenomanian (with Inoceramus concent [ unclear: ] ricus and Tun [ unclear: ] ilites cu [ unclear: ] cumltiaenatus)|
|Wharf Mudstone and Basal Conglomerate||Albian (Lower Utat [ unclear: ] u t [ unclear: ] auna—Woods, 1917)|
The well-known fauna of the Piripauan stage (Upper Senonian) has not been found in the type section with the Clarence Series. Field evidence suggests that the Piripauan may be represented by unfossiliferous beds above the Clarence Series in the apparently conformable sequence exposed—perhaps by beds that have been altered so that they are now part of the thick flint (or chert) formation that overlies the Sawpit Gully Mudstone. An alternative view has been advocated, however, that the failure as yet to find beds referable to the Mata Series anywhere (in the South Island, at any rate) following the Clarence Series necessitated belief in at. least a non-sequence, and perhaps an orogenic break, between the series, though in the Clarence section there is no discordance of dip between beds definitely referable to the Clarence Series and the other Notocenozoic formations above these to support such a theory. Publication of a new survey of the northern part of the Clarence Valley will, no doubt, either verify or negative a suggestion made (orally) by Mr. H. W. Well man that a critical part of the section in the vicinity of Coverham (Woods, 1917, Fig. 2) is cut out by a strike fault.* It was from this section that most of the fossils were collected on which the age of the Clarence Series was established. The view that there is strong unconformity in the section has been expressed in the following generalization by Wellman (1950).
[Footnote] * Postscript: More recently, however, in the communication of 12/8/54 referred to in an earlier footnote, Mr. Wellman has reported that some fossils that indicate the presence of the Piripauan, as well as, quite possibly, a complete sequence of Ci [ unclear: ] etaceoun–Tertrar [ unclear: ] y passage beds, have been found in the Clarence Valley syncline only a short distance north-east of the line of the type section.
The postulated mid-Cretaceous orogeny has to be inserted at an unspecified horizon in the Clarence section, which appears to be unbroken; for “Lower Cretaceous sedimentation” is used for accumulation of the Clarence Series as well as the problematical Tai [ unclear: ] tai Series, of the North island, of Aptian age. Little is known of the content of the Taitai Series, however, and areas of deformed rocks mapped as Taitai are probably of various Hokonui ages. There is considerable doubt of the validity of arguments that have been adduced to show that the post-Hokonui orogeny was a comparatively minor disturbance and that the most intense deformation of pre-Notocenozoic rocks took place in “mid-Cretaceous”, or post-Clarence, time. According to this interpretation of events, however, it was only after this later (hypothetically more intense) orogeny that widespread peneplanation took place, developing the well-worn-down floor on which the younger Notocenozoic formations lie A somewhat similar conclusion had been reached by Macpherson (1948).
Certain formations on the West Coast of the South Island and perhaps also at Kaitangata, Otago, have been shown by Wellman (1950) to lie unconformably below local developments of Notocenozoic, the oldest marine beds of which are, on the West Coast, Eocene. (These latter are marine beds which succeed non-marine “quartzose coal measures”.) It does not follow, however, that the formations unconformably beneath middle or late Notocenozoic strata are necessarily of early Notocenozoic age. The unconformable relationship does not indicate, therefore, that orogeny occurred in mid-Cretaceous time. The presumably pre-Notocenozoic formations in question, which include the thick, indurated Paparoa formation, of Westland, and the Hawk Crag Brec [ unclear: ] cia and Ohika formations, in the Buller district, are all non-marine, their only identifiable fossils are plants. Some or all of these formations are probably of Hokonui age—those, at any rate, which underlie the “quartzose coal measures” with angular unconformity. Thus their deformation can plausibly be attributed to the post-Hokonui folding (and no later revolution, or orogenic paroxysm, is required to account for it). It is significant that in the districts in which these formations are present—notably on the West Coast of the South Island—no beds representing marine facies of the Hokonui System have been found (Cotton, 1951).
Apart from the type locality and adjacent parts of Marlborough (including probably some outcrops between the Seaward Kaikoura Range and the sea) beds of the Clarence Series are not known except in east coast districts of the North Island, where they are represented by formations of the Raukumara group, outcropping widely in the Gisborne–East Cape district and extending south into southern Hawke's Bay and East Wellington. These are indurated sandstones and mudstones which, though in the main very poorly' fossili [ unclear: ] ferous, have yielded Inocerani [ unclear: ] us bi [ unclear: ] corrgatus and microfaunas that allow of correlation with the Clarence Series I. bicorrugatus is present in the Nidd Mudstone of the Clarence section (see Table II).
(Three stages: Piripauan; Teurian, Wangaloan)
Wherever the conspic [ unclear: ] nous while limestone formation (Amuri Limestone, in (the broad sense) outcrops in Marlborough find North Canterbury beds of the Piripauan stage are exposed below its escarpment—except in those localities,
already mentioned, in which the Clarence Series is present instead and Piripauan strata have not been recognized. In very numerous sections the limestone has below it moderately thick to thin elastic formations at least in part Piripauan, this latter lying with strong angular unconformity across the bevelled edges of older greywacke strata (of Hokonui age for the most part).
Within the Piripauan stage paleontological zoning has not yet been found possible, no faunal differences between the beds being recognized by Woods (1917) or others who have examined the molluscan fossils. Neither is the li [ unclear: ] thological succession constant from place to place; but the sequence of beds long known in the (type) coastal section at Amuri Bluff (or Piripaua, from which the stage name is taken) is often quoted, as it was measured and described by McKay in 1877 (Fig. 3).
Text-Fig. 3.—The coast section north of Amuri Bluff. Marlborough, showing the beds of the Piripaun stage in the type locality followed by the Amuri Limestone. (After Marshall, Speight, and Cotton.)
Section at Amuri Bluff:
Woods (1917) cites the succession, as below, on the authority of McKay. All below he limestone proper, that is, the sequence capped by upper “Teredo Limestone”, is regarded as Piripauan, according to the original definition of the stage by Thomson (1917); but belemnites from just below the upper “Teredo Limestone” (in another section, though not actually collected from the type section) are found to be younger than Piripauan—that is, of Teurian age—by Finlay and Marwick (1947). The succession is as follows:
|Teredo Limestone (upper)|
|Greensand Group||Grey Sandstone|
|Lower Teredo Limestone|
|Amuri Group||Lower Black Grit|
|Lower or Wood Sands|
The basal beds, “Wood Sands”, have yielded petrified wood, including a well preserved Araucarioxylon stem. From the Calcareous Conglomerate have come most of the molluscan fossils collected from the Amuri Bluff section. The most significant of these are species of Chei [ unclear: ] robelus (belemnite), Madrasites, Gaudryceras, Hamites, Struthioptera, Conchothyra, Astarte, Lahillia, and Trigonia (Geological Survey, 1948); elements of the fauna seem to indicate an age younger than any known fossiliferous horizon of the Clarence Series.
McKay's division of the Calcareous Conglomerate into “beds” has been found by Woods (1917) to be of no value, for its fossils indicate a single zone, and the local separation into beds in the beach section does not persist in others. The higher beds of the Amuri Group belong probably to the same zone as the Calcareous Conglomerate, but they have not yielded enough fossils to make this certain.
In the Greensand Group, the Saurian Beds contain marine reptilian bones, for the most part scattered through large spherical calcareous concretions. The Concretionary Greensands are poorly fossiliferous, and species in them seem to be all identical with the fauna of the Calcareous Conglomerate.
From higher horizons insufficient macrofossils have been collected to indicate the age (with the exception of the layer, referred to above, which has been dated by means of belemnites as younger than Piripauan—i e., of Teurian age).
The overlying white, fine-grained limestone is of post-Cretaceous age, according to microfaunal evidence This is the Amuri Limestone, not only in the broad sense in which that name may be applied to widely outcropping limestone strata (with a probably wider age span than this) throughout Marlborough and North Canterbury, but also in a strict sense, this being its type locality (Finlay, 1948). Finlay, reporting on samples containing a microfauna (collected by Dr. Brian Mason), has defined the age as Lower or Middle Eocene; but lithologically similar limestone continuing above tins horizon, which some have regarded because of its stratigraphical position as the equivalent of the “Weka Pass Stone” of North Canterbury, is of Middle Oligocene age. At North Canterbury localities Amuri Limestone, in the broad sense, above a Piripauan sequence and quite similar lithologically to that of the type locality, is Oligocene throughout (on foraminiferal evidence). Finlay's reference (1948. p. 296) to the limestone of North Canterbury as “a different bed” suggests a “two-limestones theory” for the Amuri Limestone similar to that which has been a subject of controversy in the past in the Oamaru district (referred to on page 1106); but there has never been any doubt of the lithological continuity of the Amuri Limestone formation— i.e, Amuri Limestone in the broad sense.
Beds beneath the widespread Amuri Limestone (broad sense) of North Canterbury include Piripauan, which there extends to the base of the Notocenozoic sequence (as at Amuri Bluff) and is strongly unconformable on a floor of much older rooks. The best known sections are those of the Waipara–Weka Pass district (Thomson, 1920). Thomson regarded all the beds below the “Amuri Limestone” as Piripauan; but foraminiferal evidence since investigated indicates that the Piripauan boundary is considerably below the base of the limestone, which is of Oligocene age (Finlay, 1948). It appears that there are passage beds from Cretaceous to Eocene in a greensand formation, or glauconitic marl, in which Finlay (1948, p. 295) has recognized Forammifera of (possibly) Paleocene and
of Eocene age. The section below the limestone (Fig. 4)., as described by Thomson (1920), consists of:
Text-Fig 4—The Waipara Gorge section, North Canterbury, showing Piripaun at base, followed by higher Notocenozoic formations. (After Marshall, Speight, and Cotton.)
The “coal measures” are “carbonaceous shales, limonite sandstones, and sands, with thin seams of coal”. The “Ostrea Bed” is a “sandstone cemented by calcite, resting on a shell bed mainly composed of oyster shells”. The “Saurian Beds” are “purple glauconitic mudstones passing into sands”, and contain large spherical calcareous concretions enclosing reptile bones, and this appears to be the same horizon as that of the “Saurian Beds” at Amuri Bluff. The “Waipara Greensands” are “glauconitic sands with hard, thin bands of greensandstone,” which, as indicated above, are now known to be for the most part post-Piripauan.
Mount Grey Section:
A section in the Mount Grey district, a short distance south-west of the Waipara section, which has been described by Mason (1941), indicates a passage upward to Eocene below the “Amuri Limestone''; but in this section the limestone facies is very thin (near its feather-edge southern limit), and the succession of formations below the limestone differs from that at Waipara. It is:
“Amuri Limestone” (very thin)
Greensand (very thin)
Concretionary Sands (probably equivalent to the “Saurian Beds”)
Foraminifera in the Loburn Clay (according to Finlay) indicate correlation with “the top of the Saurian Beds at Waipara” (Mason). The thin greensand which follows is of undetermined age; but the Ashley Mudstone following it is shown by its microfauna to be of Mangaorapan (Lower Eocene) age (Finlay, 1948), and the Karetu Sandstone has an Upper Bortonian microfauna. Both the Upper Cretaceous and Eocene strata are here very thin; and, as no physical break is evident in the section, it would appear that the thin greensand layer records an extremely long period of very scanty accumulation—comprising the Teurian and Wangaloan ages.
Malvern Hills Section:
In the Malvern Hills, west of Christchurch, fossiliferous beds have long been known which are the approximate equivalent of the Amuri Group at Amuri Bluff. The succession is:
|Saurian Beds||Perhaps exactly correlative with the Saurian Beds at Amuri Bluff|
|Selwyn Rapids Beds||Richly fossiliferous, and equivalent to the upper part of the Amuri Group. (Most significant fossils are species of Kossmaticeras, Conchothyra, Struthioptera, and Lahillia, with Trigonia pseudocaudata (Geol. Survey, 1948, p. 20)|
|Ostrea Beds.||Regarded as equivalent to the lower part of the Amuri Group (Calcareous Conglomerate)|
|Quartz sands and conglomerates, with coal|
Woods (1917) found the fauna of the “Calcareous Conglomerate” and the Selwyn Rapids Beds to be that characteristic of the Upper Senonian transgression in the Indo-Pacific region. Related forms are found in New Caledonia, South Africa, Madagascar, and Pondicherry; but the closest ties are those with Chile, Patagonia, and Seymour Island (Antarctica).
Trechmann (1917), who independently studied the gasteropods, agreed with Woods. Wilckens (1922) is in general agreement, but states more precisely that an overlap of the Campanian stage of the Uipper Senonian is represented. According to him, the nearest relatives of the Piripauan molluscs are found in Patagonia and Graharmland (Seymour Island).
Conchothyra, a gasteropod genus remarkable because of heavy callosity of the shell, has been thought to be related to the Patagonian Pugnellus, but is now regarded as an endemic form, being probably derived (according to Marwick) from Arrhoges haastianus Wilckens.
The Saurian Beds have yielded bones of Leiodon, a Mosasaur, and Cimoliosaurus, a Sauropterygian, both related to species in the Senonian of Nebraska. Absence of Ichthyosauria is significant as an indication of an age probably postdating the extinction of those reptiles.
Shag Point Section:
Another early-known locality for the Piripauan stage is north of Shag Point, on the North Otago coast, where a bed with marine fossils (Herbert Formation) overlies leaf beds and coal seams of late Mesozoic age probably unconformably below and perhaps considerably older than the Piripauan of the Herbert Formation. The latter consists at' sandstone with fossiliferous calcareous concretions.
South-west of Dunedin there are some outcrops that yield Piripauan fossils, notably the Brighton Limestone formation, at Brighton, which contains belemnites of an undetermined genus These appear to be similar to some found at the top of the Herbert Formation, at Shag Point.
Piripauan in the North Island:
In the Gisborne, Hawke's Bay, and East Wellington districts the argillitie Whangai Formation (Tapuwaeroa Formation in part) is correlated with the Piripauan on the evidence of Foraminifera. The Tapuwaeroa Formation contains few molluscan fossils, but Ostrea lapillicola Marwick has been found in it at several localities, including the Tapuwaeroa Range. Far south of this, at Mataikona, north of Castle Point, on the Wellington east coast, beds referred to the Tapuwaeroa Formation stratigraphically overlie a fossiliferous mudstone facies of the Raukumara Formation containing Inoceramus bicorrugatus Marwick. the index mollusc of the Nidd Mudstone in the Clarence Valley section (Finlay and Mirwick, 1940). This development of Tapuwaeroa contains Ostrea lapillicola, and beds at a neighbouring locality that have also been correlated with the Tapu-waero Formation have yielded an ammonite, a species of Parapuzosia, which in Australia is a Lower Santonian genus. If this evidence is sufficient to indicate Piripauan age, and if the local development of the Raukumara Formation (with Inoceramus bicorrugatus) is correctly referred to the Clarence Series, the latter and the Piripauan appear to be present in sequence in the North Island. In the South Island they are reported as present together in only one section, at Kekerangu (Macpherson, 1948), and conformity between beds definitely representing them has not been established.
Beds that overlie the Tapuwaeroa Formation in the East Cape district with some resemblance to a transported sheet, or nappe, above a “Taita [ unclear: ] i thrust”, may be older than the Tapuwaeroa, though an Aptian age that has been tentatively assigned to them by lithological correlation with fossiliferous Taitai Series at another locality has not been confirmed paleontologically.
In North Auckland, the Otamatea Formation (of the Geological Survey), known at a number of localities, which is largely a highly siliceous siltstone, includes also a mudstone with calcareous concretions that have yielded ammonites of very numerous genera, including Phylloceras, Gaudrycerus, Acanthoceras, Madrasites, and Jacobites. The fossil-bearing formation and its fauna were describe by Marshall (1926) as the Batley Series. In the sequence above these beds there is a much disputed argillaceous limestone known locally as the Hydraulic Limestone, which some geologists have considered to be the northern equivalent of the Amuri Limestone. The “Batley” ammonite fauna, rich in species, was compared by Marshall with Indo-Pacific Upper Cretaceous ammonites, especially the abundant fauna of India. He reached the conclusion that it is the equivalent of the Aryalur and Valudayur of India, which would place it at a very high Cretaceous horizon—Upper Santonian or, according to some authorities, even Maestrichtian. In the “Batley” fauna there is, however, a suggestion cf the presence of a Cenomanian (Utatur) zone. If the collections contain specimens from more than one zone, it would thus appear probable that both the Clarence Series and Piripauan stage of the South Island are represented, even if, as Macpherson (1948) suggested, the older ammonites are derived fossils. The stratigraphy is obscure, and mixture of faunas in the collection seems possible, though in Marshall's opinion the total thickness of strata was insufficient to make this probable. Thus, he was inclined to regard ammonites with Utatur affinities as local survivals—a dangerous theory that has often been resorted to in New Zealand. The inference that a zone is present that is referable to the Clarence Series is supported by the more recent discovery of a sandstone containing
Aucellina (not a late Cretaceous genus) at another North Auckland locality, near Whangaroa (Geol. Survey, 1948, p. 18).
In his discussion of the “Batley” fauna Marshall refrained from reference to the Cretaceous formations of the South Island, making his comparisons of the fauna only with ammonites of other regions; but he seems to have been inclined to believe that no more than one Cretaceous zone is to be found anywhere in New Zealand. If such a view were adopted it would be a reversion to Hutton's Waipara, a single series including all New Zealand formations with Cretaceous fossils.
The Teurian stage was introduced by Finlay and Marwick (1947) as a new stage recognizable between previously known Piripauan (below) and Wangaloan (above). It is based on a type locality in Te Uri Stream, southern Hawke's Bay. It has an abundant microfauna of easily recognized foraminifera, but no other fossils have been obtained from the beds of the type locality. Strata in other localities correlated by means of microfaunal evidence with the Teurian are: part of the Waipara Greensands (containing molluscan and reptile fossil remains); a belemnite horizon below the Upper Teredo Limestone, not in the type Amuri Bluff Section but “south of” Amuri Bluff; and a mudstone with belemnites at Shag Point. Thus the total macrofauna, so far as known, is scanty; and the fact that in some sections the stage has not been reported is not to be taken as proof of non-sequence between Piripauan and Wangaloan in such cases.
The “Kaitangatan” stage, of Thomson (1917), was renamed Wangaloan by Allan (1933), that name having priority for the formation with marine facies on which the stage is based As a “series”, or formation, name Ongley (1939) has used “Kaitangata” to include Kaitangata and Taratu coal measures as well as the overlying marine Wangaloa Formation. The shelly, shallow-water sandstone facies of the Wangaloan on which the stage was based is found in the Wangaloa Beds, which outcrop in coastal cliffs near Kaitangata, Otago. It is exposed also in the Castle Hill Mine shaft, at Kaitangata, and at Boulder Hill and Brighton, near Dunedin. At the latter two localities it follows beds of Piripauan age with an appearance of conformity; but if the succession is really conformable the Teurian must be present as well.
At Wangaloa especially there is a large molluscan fauna. No ammonites have been found, however. Besides gasteropods showing affinity with those known from younger (undoubtedly Tertiary) formations, Marshall (1917), who first described the fauna, drew attention to Paleocene genera (Heteroterma, Gilbertia, Nucleopsis) and believed he recognized the Cretaceous genus Perissolax and also Pugnellus (of the Upper Senonian of Chile and Patagonia).
In another study of the Wangaloa fauna Finlay and Marwick (1937) have revised the generic determinations but agree with Marshall in placing the age near the Cretaceous—Tertiary boundary–i.e., about Danian. The Perissolax of Marshall becomes Proficus (a new genus), and the species referred to Pugnellus is transferred to Conchothyra (an endemic genus which had appeared in the Piripauan). The shallow-water facies which alone is represented is different from any found in the Piripauan, so that close comparison of the faunas is not possible; and contrast between the Piripauan and Wangaloan faunas is probably
due more to difference of facies than of age. Of genera listed, 26 are new and peculiar to the Wangaloan, 21 are described as common to Cretaceous and Tertiary, 9 are known elsewhere only from the Cretaceous, and 19 only from the Tertiary.
Evidence against Cretaceous age is found in the absence of ammonites, belemnites, Inoceramus, as well as the presence of gasteropod species (of several families) showing no archaic affinities but rather a close relationship to Tertiary species. Indication of pre-Tertiary age is given on the other hand by: (1) the presence of the gasteropod genera Conchothyra, Lahillia, Paleosephea, and several aporrheids, all with strong Cretaceous affinities; (2) the primitive or archaic character of the species representing genera included in Tertiary families; and (3) the fact that the species representing many families that are important in the Tertiary of New Zealand differ widely, even generically, from their relatives in the low Tertiary. For these reasons correlation with the Danian rather than with tin Paleocene is favoured.
Though thin and without macrofossils in some sections the Wangaloan, and Teurian also, are present, with little doubt, in most of the sections in the northeastern and southern parts of the South Island which, though clearly exposed, show no physical break in a succession from Piripauan below to lower Tertiary fossiliferous beds above. Along the coast northward from Shag Point the (Piripauan) Herbert Formation is followed by Katiki, Otepopo, and Moeraki formations (700 feet thick in all) for all or most of which a Wangaloan age has been suggested (Geol. Survey, 1948, p. 20). A few miles south of Shag Point, in the Goodwood (Palmerston) district, glauconitic sandstone 600 feet thick bridges from Piripauan at the bottom (as proved by macrofossil evidence) to Lower Eocene at the top (Geol. Survey, 1948, p. 20.)
The Amuri Limestone Formation perhaps Wangaloun in Part:
The Amuri Limestone Formation (in the broad sense) as developed in the north-east of the South Island may be in part (where its thickness is 1,000 to several thousand feet) as old as Wangaloan. Woods (1917, p. 2) recognized the possibility (though he did not think it probable) that the lower part of the Amuri Limestone in the Clarence Valley might be of Piripauan age or even older. Correlation with the Wangaloan was suggested for the Amuri Limestone as a whole by Thomson (1917), but the only evidence he could find in support of this was its position in sections between Piripauan and Tertiary beds.
Though microfaunal investigation has shown parts of the formation, where it is thinner, to be of various early Tertiary ages, geologists of an earlier generation thought it Cretaceous, probably because of its purity, fine grain, and appearance as of indurated chalk; and those who claimed to find evidence of strong unconformity between Tertiary and Cretaceous placed this at the top of the Amuri Limestone. Thomson, on the other hand, who favoured the hypothesis that the Notocenozoic sequence was unbroken by any regional unconformity, saw a transition zone of passage beds between the Cretaceous and Tertiary in this enigmatic and apparently unfossiliferous formation. That this is not literally correct everywhere has been made clear by the identification of the thin and very slowly accumulated greensand layer as the passage bed at Mount Grey and of the somewhat thicker Waipara Greensands in the Waipara–Weka Pass district— as already described. The passage has been shown to lie at some horizon in the
greensand—i.e, below the base of the Amuri Limestone as locally developed— only at the extreme southern limit of the Amuri Limestone facies, where the limestone thins to a feather edge. It is quite possible that in the Clarence Valley and in eastern Marlborough, where the limestone facies is very thick and where (over a considerable area) the lower thousand feet of the formation is replaced by the chert of the “flint beds”, that the limestone, or possibly its chert replacement, includes the passage beds. This would mean, of course, that some part of the formation not yet identified, though not the whole of it as Thomson suggested, must be referred to the Wangaloan stage.
This limestone is strikingly free from terrigenous sediment, and has accumulated as a calcareous ooze containing some Foramim [ unclear: ] fera and with little or no terrigenous mud content. Silica is abundant in it—some of tins, according to Thomson, as well as much fine-grained calcite, probably precipitated inorganically. Much silica has been collected into the massive flint layer, which perhaps indicates secondary replacement, though this has not been demonstrated.
There is remarkable uniformity in the macroscopic appearance of the limestone wherever it outcrops, largely because of a conspicuous platy jointing (parallel to the bedding) invariably present in this but only rarely simulated in other limestones.
In Marlborough there is a gradual passage from the upper horizon with limestone facies (indicated by the microfauna to be Oh [ unclear: ] gocene) upward into marl and mudstone; but farther south (i.e., in North Canterbury) the Amuri Limestone, there much thinner and all of Eocene to Oligoecene age, is followed by another limestone stratum, lithologically different and conspicuously without the platy jointing, but, in that district, equally widespread. This is the Weka Pass Stone formation. It contains a sprinkling of glauconite grains throughout and is richly glauconitic in the lowest few inches, which may be described as calcareous greensand. At the base of this basal layer there is some phosphatization.
There is thus a distinct discontinuity between two limestone formations, though without the smallest discordance of dip or strike. This is shown by the fact that where the one formation is present the other is always with it throughout hundreds of square miles of gently folded and strongly faulted terrain forming a landscape of considerable relief. In this the junction between the two limestones with contrasting facies is exposed on the faces of escarpments and along valley sides. Outcrops are innumerable, and few of them are obscured by the scanty vegetation.
This junction is of great historical interest. Though known now to be only a minor break between Tertiary formations differing little in age, it has been mistaken for a major unconformity between Cretaceous and Oli [ unclear: ] gocene or Miocene Finlay and Marwick (1940) remark: “The importance of the break between the Amuri Limestone (Whaingaroan at the top) and the Duntroonian Weka Pass Stone has been the subject of one of New Zealand's longest controversies. Now that the microfaunas are adequately known, the break assumes new importance, not so much in time as in the fact that the real faunal severance from the earlier Tertiary [not the Cretaceous] … seems to occur here”
The non-sequence in sedimentation can be explained without appeal to a hypothesis of emergence. It has been largely the result of an influx of sufficient terrigenous sediment to form a certain amount of glauconite, though a compacting
of the bottom and some phosphatization of it may indicate complete cessation of deposit prior to this. A very remarkable feature of the contact, and one that is strangely constant throughout many miles of outcrops, as Speight and Wild (1918) have put on record, is that the calcareous greensand forming the basal layer of the Weka Pass Stone formation penetrates into recesses that appear to be worm borings in the top layer of the sediment forming the Amuri Limestone. These are several inches deep, and they separate narrow projections, or peninsulas, which, when exposed in vertical section, have been mistaken for pebbles of the limestone. Another suggestion that has been made is that the openings into which the overlying deposit penetrated were made not by organisms but by solution enlarging joints already developed in the material in the characteristic pattern now to be seen in all outcrops of Amuri Limestone.
Among the geologists of last century it was F. W. Hutton in particular who insisted on a break between his Waipara (Cretaceous) and Oamaru (Oligocene or Miocene) systems at this horizon. Later, Park oscillated, in successive accounts of the geological succession, between belief and disbelief in such a break. P. G. Morgan was another proponent of the theory that a great gap here separated Cretaceous and Tertiary.
[The section below cannot be correctly rendered as it contains complex formatting. See the image of the page for a more accurate rendering.]
|Wanganui||Castlecl [ unclear: ] iffian||Pleistocene (perhaps in part Upper Pliocene)|
|Nukumaruan||Upper Pliocene (probably in part Pleistocene)|
|Waitotar [ unclear: ] an||Lower Pliocene|
|Altom [ unclear: ] an||Lower Miocene|
|Whaingai [ unclear: ] oan||Lower Oligocene|
|Kai [ unclear: ] atan||Upper Eocene|
|Mangaoi [ unclear: ] apan||Lower Eocene|
Above the passage from Cretaceous to Tertiary the Notocenozoic continues in a succession of series that are not marked off by breaks in sedimentation, but are groups of stages it has been found possible to separate from one another by paleontological study (particularly, in recent years by recognition of their microfaunas).
To the small number of stages originally proposed by Thomson (1916) others, all characterized by marine faunas, have been added until 23 are now recognized. The grouping of these into series adopted by the Geological Survey (1948, p. 23) is as shown in Table III.
The “Oamaru SYSTEM”
From some points of view it is regrettable that the well known designation “Oamaru” for a system—formerly considered the oldest division of the Tertiary present in New Zealand—has now disappeared from the officially recognized classification. After its first use by Hutton in this sense the connotation of “Oamaru” was unduly extended by Marshall to include both older and younger groups of strata until its content embraced nearly the whole of the Notocenozoic. This expansion was later abandoned, however, was corrected by re-definition, and is not the reason for the more recent abandonment of this old group name by the Geological Survey. The group of “Oamaru” stages is deemed disproportionately large, comprising as it does all nine of the stages now distributed among the conventionally defined Arnold, Landon, and Pareora Series (Table III), ranging in age from mid-Eocene to Upper Oligocene.
The “Oamaru” series, system, or group is of more than historical interest, however, for the use of this designation wherever it can be retained recalls the fact that the strata in the Oamaru (North Otago) district are rich in fossils and supply type sections for several stages that are still retained intact, as well as others, formerly recognized, which have been subdivided. These earlier recognized stages are not, however, representative of the oldest Tertiary, though this is present, perhaps in unbroken sequence, between the early known Tertiary formations of Oamaru and the Piripanan–Teurian–Wangaloan (or Mata Series) of the coastal belt north of Shag Point; for the intermediate Kurinui Formation, near Hampden, consisting of glauconitic mudstone, contains at least a Heretaungan microfauna (Geol. Survey, 1948, p. 33).
The Dannevirke Series (Paleocene and Lower Eocene, according to micro-faunal correlation) is represented in the type section (in the Dannevirke district of the North Island, where the type sections of all four stages of the series are defined) by 640 feet of silty mudstones with glauconitic layers. Throughout the New Zealand region all beds definitely attributed to this series are “fine, muddy to silty, marine sediments without macrofossils [except at one locality, Tioriori, Chatham Islands] and having considerable glauconite … The thicknesses are restricted, not geosynclinal, and of the order of a few hundred feet” (Geol. Survey, 1948, p. 27).
The Waipawan stage (Paleocene) overlies the uppermost Cretaceous in the section in which the type Teurian is defined (Te Uri Stream, 10 miles west of
Poranjahau). This exposes strata dipping steeply eastward along the stream for three-quarters of a mile. Above the Teurian mudstone, which overlies a bed with Piripauan microfauna, and separated from the Teurian by an erosion surface, though without discordance of dip, are beds with the “Waipawa Black Shale” microfauna (formation name from another section in the bank of the Waipawa River, Hawke's Bay), which is correlated tentatively with the Wangaloan because of its stratigraphical position in the section and affords a microfauna assumed to be Wangaloan. This equivalent of the Waipawa Black Shale is not itself representative of the Waipawan stage, but is followed by it. The Waipawan stage in this section is characterized by its foraminiferal microfauna. The beds are “hard and soft greenish mudstone with some greensand at the base, the whole about 250 feet thick.”
The Mangaorapan stage (assigned to Lower Eocene) follows the Waipawan in sequence at the Te Uri Stream locality. The beds representing it, above the Waipawan, consist of “60 feet of massive blue-grey mudstone with dark streaks”, and are distinguished only by the microfauna from beds below and above. Though no macrofauna is known from any locality on the main islands of New Zealand, Mangaorapan Foraminifera are found in association with molluscs and brachiopods in the “Notostrea Bed” at Tioriori, Chatham Islands.
The type Heretaungan follows the Mangaorapan in the Te Uri Stream section. Here the beds consist of “some 80 feet of hard grey mudstone with pockets of glauconite, dipping east at about 60°” and contain a distinctive microfauna. No mollluscs are known in this or other sections, but beds correlated by microfauna with Heretaungan that occur at Abbotsford, near Dunedin, contain a fossil fish, Portheus dunedinensis Chapman.
Beds of the Porangan stage follow, containing another distinctive microfauna older than Bortonian. In the Te Uri Stream section those representing this stage consist of 250 feet of “hard grey mudstone with some pyritic concretions”. These pass up, without change of dip, into mudstones containing the Bortonian microfauna at the end of the exposed section of Cretaceous–Tertiary passage beds in the Te Uri Stream. Dipping uniformly eastward at 60°, beds are here exposed in continuous section that are referable to Piripauan, Teurian, Wangaloan, Waipawan, Mangaorapan, Heretaungan, Porangan, and Bortonian stages, all represented by similar facies of very slowly accumulated sediments. More rapid sedimentation began in the Bortonian, however, and succeeding stages are represented in the Te Uri column (Lillie, 1953, p. 33) by progressively thicker formations, though these are mainly mudstones, so that the total thickness of beds representing post-Porangan stages, up to and including the Altonian, is about 4,000 feet.
Arnold, Landon, and Pareora Series
The “Oamaru System”, as perhaps it may still be called, comprising the Arnold, Landon, and Pareora Series, with its type locality the Oamaru district of North Otago (and its extension into South Canterbury) includes the oldest Tertiary strata in the New Zealand region that have yielded molluscan fossils,
with the single exception of the bed of Mangaorapan age at Chatham islands already mentioned.
The Oamaru district is important in the history of New Zealand geology not only because of the early study of richly fossiliferous Tertiary strata there by Hutton and others, which led to a clear conception of the general sequence of early to middle Tertiary formations, but no less so also because Thomson (1916) there selected the types of his earliest defined Tertiary stages. As yet only four marine stages were distinguished in this group—for an underlying non-marine “stage”, the Ngaparan of Thomson, must be left out of account. The marine stages were: Waiarekan, Ototaran, Hutchinsonian, and Awamoan; but the first two names are no longer used. The statement in Table IV indicates the relation of stages later substituted and intercalated to the original four.
Thomson's stage names were based on lithological units, or formations, already recognized and well known at Oamaru, as follows.
|Lithological Unit (Formation) at Oamaru||Stage|
|Hutchinson Quarry Beds||Hutchinsonian|
|Waiareka Tuffs and Enfield-Windsor and Ngapara Greensands||(Waiarekan)|
|Coal-measures, sands, Conglomerates, and Coal Seams (all non-marine)||“Ngaparan”|
(In the Oamaru district the lithological succession varies considerably from place to place because of contemporary volcanic activity. Lavas and tuffs, for example, take the place of limestone in some places.)
|Thomson (1916)||Allan (1033; 1938)||Finlay and Marwick (1940)||Finlay and Marwirk (1947)|
(Names enclosed in brackets have become obsolete.)
Various changes in the definition and nomenclature of stages have been made since stages were first proposed by Thomson. The suggestion of a Bortonian stage first made by Park (in 1918) was adopted by Allan (1933), who based
it on a greensand formation better known in South Canterbury than in the restricted Oamaru district. The “Tahuian” stage, also introduced by Allan, who based it on a higher greensand horizon in South Canterbury, has since been found unnecessary and is no longer used by the Geological Survey. The stage name Waitakian was also first used by Park (1918), who, however, thought the stage the equivalent of “Upper” Hutchinsonian. Recognition that it is older than Hutchinsonian, due to Allan (1933), has led to its acceptance as a stage. Allan introduced Duntroonian in 1938. “Ototaran” time is distributed now in three ages established by Finlay and Marwick (1940; 1947)—namely, Kaiatan, Runangan, and Whaingaroan.
This so-called stage is no longer regarded as such, as it was founded on non-marine beds that cannot be correlated with marine strata of defined age. The age of the Ngapara Formation of coal measures, etc., is unknown. It may be Cretaceous or Eocene or partly Cretaceous and partly Eocene. Allan (1933) therefore omitted “Ngaparan” from the “Oamaru” group.
The Bortonian is based on the oldest greensand fauna at Black Point, inland from Oamaru, contained in the lowest marine formation in that locality, which immediately overlies lignite-bearing fresh-water beds. At this type locality Park enumerated 43 species of mollusc, of which 8 were considered “recent”. The Bortonian stage is better developed in South Canterbury in the lower part of the Waihao Greensand, in which there is a well-preserved fauna, whereas the fossils at Black Point are only casts.
The Bortonian stage is known at many places from end to end of New Zealand; but interest centres particularly on those localities in which beds of Bortonian age follow conformably after Cretaceous–Tertiary passage beds. In North Canterbury sections these are exposed below or at the bases of escarpments capped by Amuri Limestone or a massive formation including both Amuri Limestone and Weka Pass Stone. There is also the Te Uri Stream section, already described; and in a coastal section in eastern Otago the Piripauan (Upper Senonian) north of Shag Point is linked with the extensively outcropping Tertiaries of the Oamaru district. In this section the Hampden Formation is of Bortonian age and has beneath it the passage beds of the Dannevirke Series and Wangaloan.
In addition to microfaunal evidence indicating a Mid-Eocene age for the Bortonian further evidence is afforded by the presence of some molluscan genera of restricted range known in other regions. Several of these indicate Lower to Middle Eocene age, and one ranges from Middle to Upper Eocene (Marwick, 1934). The Bortonian macrofauna is of particular interest in that it is (with the exception of the small Mangaorapan fauna obtained from a Chatham Islands locality) the earliest post-Cretaceous, or definitely Tertiary, fauna of this region. Although the matrix of the type Bortonian locality is greensand, the shells, according to Marwick (1934), are those of shallow-water molluscs (living in depths of from 10 to 20 fathoms). The relatively modern aspect of these is indicated by Marwick's statement: “Many of the Bortonian species are the earliest-known members of lineage series which can be traced up as far as the Miocene, and some—e.g, Friginatica, Cirsotrema, and Austrofusus—even to Recent times,”
The fauna is sharply differentiated from that of the Cretaceous as represented in the Piripauan (Upper Senonian) and even the Wangaloan (Danian). According to Marwick's statement, “the Wangaloan by no means bridges the [Piripauan-Bortonian] gap”. Only one out of 38 species in the Bortonian is regarded by Marwick as having a highly probable ancestor among known species of the New Zealand Upper Senonian, and, though two others have possible but very doubtful ancestry there, “for most of the species the possibility is either extremely remote or, does not exist”. Suggestions of possible reasons for this non-sequence in molluscan life are: (1) imperfections in the record and difference of station; (2) great lapse of time; (3) invasion; (4) change of climate.
(1) The first was considered by Marwick (1934) to be unacceptable as a complete explanation, for not only the type Bortonian fauna but also others of shallow-water facies from various parts of New Zealand have been compared with that of the Upper Senonian.
(2) Lapse of time he considers quite insufficient to allow for progressive evolutionary development to explain the change. This argument probably still holds good despite the fact that, since the publication of Marwick's discussion of the problem, a considerable difference in age has been demonstrated by the discovery of the Dannevirke Series, which, however, has not yielded molluscan fossils to throw light on the evolutionary changes in progress.
(3) Marwick favours invasion to account best for the substitution of a new for an old fauna. The relationship of Bortonian molluscs to those of other regions is much closer than to those of the Upper Senonian of New Zealand. Yet, if the Bortonian fauna marks an invasion, “the immigrants came from an area of which the Lower Eocene fauna is as yet unknown”. This, however, “presents no difficulty” (Marwick). Contemporary with this postulated pre-Bortonian invasion there may have been a land and shallow-sea connection far to the north and north-west, and at this time, instead of as generally supposed during the Lower Cretaceous orogeny, New Zealand may have acquired its Malayan floral element and its peculiar land snails and struthious birds.
(4) Change of climate is regarded as a less likely cause of faunal change than invasion. The transition from Cretaceous to Eocene was marked, nevertheless, by rapid faunal changes in other parts of the world as well, and these have been attributed to a hypothetical climatic refrigeration at the close of Cretaceous time.
Age of Island Sandstone and Kaiata Mudstone Formations:
Morgan (1921) maintained the opinion that two early Tertiary marine formations, the Island Sandstone and Kaiata Mudstone, extensively developed on the West Coast of the South Island, were older than any that had been described in the Oamaru district. Morgan regarded the oldest marine stages defined by Thomson at Oamaru as Miocene, and believed them to be separated from his own Eocene “Mawheranui or Waimangaroa Series” (on the West Coast) by a regional unconformity—a view he embodied in a correlation table (Morgan. 1921). He added, therefore, to the list of stages defined by Thomson two further marine stages, “Islandian” and “Kaiatan”, named from the Island Sandstone and Kaiata Mudstone members of his Mawheranui group.
Beds overlying these unconformably (the “Omotumotu Beds”) contain rolled pebbles of coal derived from coal measures below the Island Sandstone, and these
Omotumotu Beds Morgan regarded as equivalent in age to the Ngapara Formation beneath the marine formations at Oamaru. Thomson (1916) had, however, assumed the Brunner Coal Measures, which underlie the Island Sandstone, to be more or less equivalent to the Ngapara Formation, and had correlated both Island Sandstone and Kaiata Mudstone with his “Waiarekan” (now Bortonian). With the “Kaiatan” Morgan included the Hampden Formation, south of Oamaru, which is now regarded as Bortonian.
Morgan's “Islandian” stage is not now retained, as it is equivalent to Bortonian; but the name “Kaiatan” is recognized by the Geological Survey and applied to a stage for which the type section is the lower part of the Kaiata Mud-stone formation (p. 1098). Its equivalent at Oamaru is the lower part of the Ototara Limestone formation.
Morgan turned out to be in error in correlating with the Ototara Limestone the Cobden Limestone of the West Coast, which is now known to be younger (Whaingaroan to Waitakian). This limestone is a member of the Greymouth group, or “series”, which comprises, above the Omotumotu Beds (containing coal pebbles as already mentioned), Point Elizabeth Beds and Cobden Limestone. These are followed by the Blue Bottom formation, which is now known to range in age through stages of the Southland and Taranaki Series.
The stage “Tahuian”, suggested by Allan (1933), which has not been adopted by the Geological Survey or included in the classifications by Finlay and Marwick, was proposed to replace “Upper Waiarekan” (with age significance). It was based on the fauna of the upper part of the Waihao Greensand formation, of South Canterbury. As this is now regarded as a facies fauna of Kaiatan age, “Tahuian” has been dropped.
There have been good reasons for abandoning Thomson's “Waiarekan” as a stage name, with substitution of Bortonian. The collection of fossils that provided the faunal list affording Thomson the basis for the stage came, it has been discovered, not, as supposed, from the Waiareka Tuffs but from the Waihao Greensand (which is Bortonian as now defined) : it had been attributed in error to Waiareka. Investigation of, and collection of fossils from, the Waiareka Tuff enabled Marwick (1926) to publish descriptions and a faunal list. The fauna of an age restricted to the time of accumulation of the tuff at a type locality he selected —on the hillside behind Lorne railway station, an outcrop also referred to sometimes; s the Lome Tuff—turned out to consist almost entirely of previously unknown species, of which he listed 27. The affinities of these indicate that the beds with Waiareka Tuff fauna should not rank as a distinct stage, the fauna being more correctly described as a facies fauna of the “Lower Ototaran” (since re-named Kaiatan). This means that it is younger than Bortonian. It was this discovery that led to abandonment of the “Waiarekan” stage. The fauna incidentally provides almost the only known record of “Ototaran “mollusca.
A remarkable formation closely associated with the Waiareka Tuff comprises lenses if siliceous ooze containing diatoms, Radiolaria, and sponge spicules, the last forming nearly the whole of the material in some lenses In this siliceous material Hinde and Holmes (1891) recognized sponges of 110 species distributed in 43 genera. They described what appeared to be mixture of sponge species
with very deep water and with shallow water affinities; and they suggested accumulation of the ooze in a sea 1,000 to 1,500 fathoms deep. From examination of closely associated deposits, however, Park (1918) has claimed that the depth was more probably between 10 and 100 fathoms.
The “Ototaran” stage, as it was defined by Thomson (1916), was the.horizon of the conspicuous limestone formation that outcrops widely in the Oamaru district. This yields scarcely any molluscan fossils, and, though it consists largely of fragments of Bryozoa, these have not yielded much information as to the age of the limestone. In places it contains brachiopods. Some lenses of tuff in a volcanic facies contain molluscan fossils (the Lorne Tuff, already mentioned, for example). The known fauna is not extensive, however.
The main reasons for abandoning Thomson's “Ototaran” stage are that the Ototara Limestone is (1) characterized mainly by a brachiopod fauna, notoriously restricted (in the Tertiary) to particular facies of deposit that are liable to be absent from sections in which the presence of the stage is expected; and (2) poor in Forammitera, which are particularly useful for regional correlation.
While the Ototara Limestone has not itself yielded fossil faunas that allow of correlation with contemporary deposits throughout New Zealand, it has been found possible to establish among these contemporary formations as many as three stages, each with a characteristic microfauna well adapted for region-wide correlation.
Before the abandonment of the “Ototaran” stage the problems of its precise definition and correlation by means of its brachiopod fauna were examined by Allan (1933), whose recommendations hold good at least for the Ototara Formation, in the Oamaru district. Allan selected as the type locality (the fauna of which might be the subject of closer study) a line of section, Trig. V to Deborah Road, figured by Park (1918, map opp p. 66). This section consists of.
|Top 1||Greensands with brachiopods Pachymagas, of the parki series|
|2||Ototaran||Deborah (or Kakanui) Limestone|
|3||Deborah Tuffs [includes Kakanui Tuffs]|
Beds 2–4 Allan defined to be the type of the “Ototaran” (together with such intervals within or between them as are duo to non-deposition or erosion).
Faunas already partly known, consisting mainly of brachiopods, indicate the presence of “several faunal communities, some definitely in sequence [zones]; others possibly facies variants” (Allan). In 1926 Thomson had indicated the presence of four faunules, one (the youngest) of which. Thomson's landonensis faunule, Allan was later (1938) to define as the characteristic fauna of a Duntroonian stage, now generally recognized as such. This's particular faunule had been regarded as a facies fauna of the Ototaran, without time significance; but the remaining three of Thomson's faunules were regarded by Allan (1933) as of zonal value, though he did not claim specifically that their ranges coincided with the litholotrical divisions (4;3; 2) in the type section. These zones are characterized by the presence of: (in the lowest) Liothyrella pulchra and Terebratella totarensis; (middle) Liothyrella boehmi, in Kakanui Tuff; and (highest) liothyrella
oamarutica, Tegulorhynchia depressa, and Tegulorhynchia sublaevis, in the Kakanui Limestone.
Finlay (1939) (see also Finlay and Marwick, 1940) recommended substitution of tie two stage names Kaiatan and Whaingaroan for Lower and Upper Ototaran—as it had become usual to name two divisions of the “Ototaran” stage —the division into separate stages being advisable because of distinctness of microfaunas in localities in which these are available for comparison. The Kaiatan stage is named from the Kaiata Mudstone formation of the Greymouth (West Coast) district, and revives the Kaiatan stage introduced by Morgan in 1921. This mudstone formation, 2,000 to 3,000 feet thick, outcrops widely on the West Coast and rests with an appearance of conformity on the Island Sandstone formation, which is of Bortonian age. Mollusca are very scarce in it, but abundant Foraminifera are available for correlation. The Kaiata Mudstone is followed by the Point Elizabeth Formation (Runangan and Whaingaroan in age).
As mentioned earlier, the molluscan fauna of the Waiareka Tuff formation, at Oamaru, is regarded as “Lower Ototaran”—i.e., Kaiatan. It contains species unknown elsewhere. One of these is referred to the genus Agathirses, which is of restricted Lutetian (Mid-Eocene) range.
Finlay and Marwick (1947) have introduced a Runangan stage between the Kaiatan and Whaingaroan. The stage is characterized by a distinctive fora-miniferal fauna present in beds sandwiched between others with Kaiatan and Whainghroan microfaunas in a continuous section exposed in sea cliffs north of Point Elizabeth, on the West Coast of the South Island. Evidence from fora-minifera species present in this type section, and also in another (of different. lithological facies) in North Otago, indicates that the Runangan is of very late Eocene age.
The type of the Whaingaroan stage is the Whaingaroa Formation, a mudstone 100 feet thick overlying coal beds at the base of the local development of the Notocenozoic at Whaingaroa Harbour, on the west coast of the North Island. Its cover consists of the Te Kuiti Limestone formation, referable in part to the Wai-takian stage.
The characteristic fossils are Foraminifera only, so that for this stage even more than for others below and above it identification is based entirety on microfaunal correlation. Despite the abundance of brachiopods representing species of a number of genera in some beds of this age—notably in the upper part of the Ototara Formation in the Oamaru district—Finlay and Marwick (1940) find these of little use for correlation, mainly because of the “gregarious nature and sporadic occurrence” of these organisms in Tertiary formations.
In the north-eastern part of the South Island, the deep submergence that was accompanied by accumulation of white, largely calcareous ooze (producing the now conspicuous Amuri Limestone, in the broad sense) had by this time been long in progress—the limestone having become very thick in the northern part of the district—but it was now drawing to a close. Where the limestone formation is thin (near its southern feather edge, for example) and at numerous places where samples have been taken from the upper layer of the deposit, the Foraminifera
in it are Whaingaroan. Finlay (1946) has noted that in the almost unique facies (unindurated chalk) of the limestone outcropping at Oxford, North Canterbury, where the thickness is only 50 feet, there is a homogeneous Whaingaroan fauna throughout. He has described the chalk as foraminiferal ooze that has accumulated under water 500 to 1,000 fathoms deep. The upper part of the Amuri Limestone formation where it is thick, and the whole of it where it is thin, are thus shown to be strictly contemporaneous in origin with the Ototara Limestone of the Oamaru district, though, in the past, various geologists have considered these to be of ages as far apart as Cretaceous and Oligocene or Miocene.
The Notocenozoic Transgression in Relation to Limestone Formation
The calcareous facies of deposit in the “Oamaru” cycle of sedimentation is dated an age or two later than Whaingaroan in some other districts, but it is true in general that this early Notocenozoic transgression culminated in only one submergence so general that deep-sea, or open-sea, calcareous ooze and a spread of other uncontaminated calcareous organic debris were widely deposited.
The “Hydraulic Limestone” and associated siliceous and argillaceous or bentonitic facies of the North Auckland peninsula have been regarded by some geologists as the equivalent in age of the Amuri Limestone of the South Island. Outcropping in a district of obscure structure, where exposures are generally poor owing to advanced maturity or absence of rejuvenation of the relief, and being stratigraphically above ammonite-bearing beds, they have been placed by some in the Cretaceous or earliest Tertiary; whereas another formation with calcareous facies, the white, partly crystalline, polyzoan limestone present only nearer the east coast and known as the Whangarei Limestone, is referable to the Landon Series, as it yields Whaingaroan and Waitakiau Foraminifera. Though the two facies have nowhere been found in the same section, the opinion has been maintained that there must be pronounced unconformity between them. Marshall (1917b), on the other hand, regarded them as essentially of the same age. Difference of facies rather than of age is now recognized to be the cause of the difference between the limestones; but it is further recognized that the facies of deposit producing the “hydraulic” limestone and associated white claystones has recurred, or differs in age in different parts of the North Auckland peninsula, so that only some, not all, beds of that facies arc stratigraphically equivalent to the Whangarei Limestone (i.e., of Landon age).
Marshall (1916) claimed that his one-limestone theory was established by thin-section work on Foraminifera. Largely because of the presence of Ampl [ unclear: ] stegina he regarded all the limestones he examined, including the Amuri Limestone, as Miocene. In his opinion the nature of the siliceous organisms in ooze that made both the Amuri Limestone and the “hydraulic limestones” of North Auckland indicated deposit at a depth of 2,500 fathoms or more.
Stability of the Region in the Early Tertiary
Marshall favoured a rather too simple theory of a single Tertiary transgression, which would account for a single phase of limestone accumulation at the time of maximum submergence throughout the region, and would allow generally of diastrophic correlation This is not compatible with the vast duration of the period of accumulation, though it would appear that for very many millions
of years large parts of the region were extremely stable, and that during all that time the conditions of slow, far-from-shore marine accumulation changed very little. As applied in explanation of the fact that the base of the Notocenozoic sequence varies in age from early Upper Cretaceous to mid-Tertiary, however, Marshall's theory of simple transgression and progressive overlap over a land undergoing gradual submergence without deformation fails to explain the facts. Positive movement of ocean level or regional subsidence even of moderate amplitude would suffice to submerge entirely the pre-existing land, which had quite obviously been reduced to very small relief. It is more reasonable to picture subsidence affecting one district in one age and another in another so as to allow transgression to take place over an already developed and continuously developing peneplain, while accumulation continued with few breaks over areas early submerged, so that continuity of strata and wide lithological correlation became possible.
The absence of any but the very finest, apparently open-water, marine sedimentation (except for little known marginal facies) in late Cretaceous and early Tertiary times indicates that an increasingly perfect planation of the adjacent lands was in progress. The perfection of this planation across the hardest rocks is well seen in fossil plains exposed now as plateaus in the northwestern district of the South Island, from which strata of Whaingaroan age have been stripped by recent erosion after the upheaval of warped and faulted mountain blocks (Cotton, 1916).
The western and north-western part of the South Island has been recently shown (by Suggate, 1950) to afford a good example of overlap of successive Notocenozoic stages (Fig. 1). The land being well planed to start with, and presumably, therefore, low-lying, this indicates development of a laterally shifting axis or zone of flexure (or less probably subsidence along faults—compare Cotton, 1945, Fig. 34) which allowed transgression to affect districts progressively farther north. That differential subsidence of the floor was in progress is shown by the great thickness of sediments in some areas of local geosynclinal development, while in other areas the “quartzose” coal measures and marine beds that follow them are thin. The predominance of quartz that distinguishes these from older coal measures in the South Island is an indication of the advanced condition of subaerial weathering and denudation of the land from which the sediments were derived.
This division of coal measures, shown by Suggate (1950) to range in age from Bortonian to Duntroonian, has also been given the name Middle Coal Measures (Suggate and Couper, 1952; Couper, 1953) and made to include some older measures more or less conformably underlying marine strata of the Dannevirke and Mata Series, ranging thus in age from Upper Cretaceous to Oligocene, so that “no direct correlation between Middle Coal Measures in different areas is possible” The description “middle” applied to these usually quartzose formations distinguishes them from “lower”, unconformably older, pre-Notocenozoic (early Cretaceous and Jurassic) measures, and also from an “upper” division dated in the late Notocenozoic regression.
In a map by Wellman (1953, Fig. 5) generalized successive positions are shown of a hypothetical shoreline in the region that is now the South Island at stages of the long-continued transgression in progress from Mata to Duntroonian times. For various reasons, however, he lost faith in this simple pattern of shoreline
migration before the map showing it was eventually published, after a delay of several years (1953, p. 33). It might well be argued, moreover, that the development of early Notocenozoic geosynclines, with which, as Wellman (1953, Fig. 7b) points out, the variable rank of coals of approximately the same age is consistent if attributed to depth of burial, could scarcely have gone on without some warping, either sympathetic or complementary, that would complicate the shoreline pattern of adjacent land, especially as such land was certainly low-lying.
A typical section drawn by Wellman (1953) across the belt affected by transgression shows progressive change in the lithology of the sediments to that of an open-sea facies with increasing distance from a hypothetical “old land” that remained throughout that vast period of very small relief and subject to thorough weathering.
A regression followed and continued during the later Notocenozoic. It was caused, as Wellman (1953, p. 38) shows, not so much by emergence (for subsidence continued in districts where sedimentation was in progress) as by a progressive increase in the volume of detritus becoming available for infilling. Thus, non-marine beds attained considerable thickness. In parts of the region, however, land was appearing as a result of local upheavals, precursor movements heralding the approach of the Kaikoura Orogeny, which was eventually to push up the whole of the mountainous South Island. Early emergence of land with some relief, probably along the axis of the Southern Alps, accounts for an increasing supply of clastic debris, including gravel, that was the main cause of regression. The “upper” coal measures, referred to above, are dated in the late Notocenozoic regression, and generally contain beds of greywacke conglomerate. They “are either conformable on marine Tertiaries or unconformable on Tertiary or older rocks” (Suggate and Couper, 1952).
The East Coast Geosyncline
In a geosyncline parallel to and east of the present-day axial range of the North Island (which was a positive area possibly throughout, the Notocenozoic and certainly during the latter part of it) the geological history has differed very considerably from that outlined above for the South Island, with its progressive overlap and a transgression of long duration culminating in an open-water limestone facies. Instead of the limestone there is in the geosyncline, notably in the Wanstead Formation of southern Hawke's Bay, a light-grey silty mudstone facies, in places bentonitic, which is poorly fossiliferous. It follows the thin glaueonitie mudstones of the Dannevirke Series. The Wanstead formation may represent all stages of the Arnold Series, there being no appearance of a physical break in it; but, though Bortonian microfaunas have been found, the presence of Kaiatan and Runangan has not yet been reported. The Landon Series is present in calcareous mudstones of the Upper Mangatu and Weber Formations in the Gisborne district and southern Hawke's Bay, in which there is microfaunal evidence of Whamgaroan to Waitakian age.
Discovery of the Dannevirke Series, followed in the type locality by a bed correlated with the Bortonian, has greatly narrowed a gap formerly supposed to separate Cretaceous from middle to younger Tertiary strata in this geosynclinal sequence. The apparent absence of beds of Kaiatan age is only negative evidence which may yet be reversed by new discoveries; and it thus seems possible that the
Landon Series is linked by continuous accumulation in some parts of this geosynclice with the underlying late-Cretaceous-early-Tertiary sequence. If the Kaiatan stage is really absent, as Fleming (1949) assumes, the whole geosynclinal area seems to have emerged in that age (Upper Eocene); but Lillie (1951) does not recognise orogeny of such a date either in the East Coast geosyncline or in North Auckland (where emergence has also been assumed).
The floor of the East Coast geosyncline became widely submerged in the Upper Cretaceous, and sedimentation seems to have gone on in it from Clarence until mid-Tertiary times with few breaks—none indeed except such as were due to local emergences—continuing with but little change of facies (after another problematical Hutchinsonian–Awamoan gap) into later Tertiary time. As regards the latter gap, Lillie (1951, p. 242) finds that “the Upper Oligocene (Pareora Series) is completely absent south of Hawke Bay, and its presence farther north is doubtful…. About late Oligocene time some fold movement occurred, which, subordinate to post-Pliocene movements, must yet have been considerable.” He adds, further: “The influx of coarse elastics in the late Lower Miocene (Upper Southland) makes a second period of widespread precursor movement at that time very likely.”
The “built-up” thickness of geosynclinal sediments possibly exceeds 25,000 feet, according to Macpherson (1949); and Henderson (1929) had earlier estimated the thickness of the Tertiary part alone in the East Cape-Gisborne district as 33,000 feet.
Macpherson (1946) has observed evidence of disconformities and angular discordances “around the flanks … of crest maxima on any dome or anticline”, while in adjacent minor geosynclinal areas there is “no obvious sedimentary break”. He has found that “on axial areas” there are “thin or compressed sections with missing units”, in contrast with “extremely thick synclinal sections”. Cores of the basement rock in anticlines project as tectonic ridges, having been raised progressively during the period the geosyncline has been in existence. Such cores are, according to Macpherson (1946, p. 15) “arch-bends developed on a buried, subdued matureland cut on the basement Mesozoic and older rocks”. He continues: “It seems further evident that they did not attain their present amplitude (possibly 7,000 to 8,000 feet above adjoining synclinal troughs) in one or two folding movements, but grew by recurrent orogenic impulses [as permanent or persistent highs], these orogenic impulses being recorder by the many forms of discordances and changes in sedimentation in the Upper Cretaceous and Tertiary sediments that envelop them. Many domes and larger uplifts … have basement rock exposed on their crestal parts over wide areas, while others are completely enveloped in sediments. Some have basement rock at comparatively shallow depth, as revealed by gravity measurement; and on several folds the drill struck basement rock at a surprisingly shallow depth. From the sedimentary record it seems clear that this basement relief, exposed or covered, originated from the late Cretaceous and mainly during post-Oligocene to late Pliocene times.”
According to this view, breaks in sedimentation that are found on or bordering the persistent “highs”, though such breaks are absent from the sequence of more continuously deposited sedimentary formations in the intervening troughs or minor geosynclines, afford evidence of at least 10 spasms of diastrophism. or incipient orogeny, a crescendo of intermittent movements leading up to an end-
Tertiary paroxysm accompanied by development of enormous faults, which perhaps still continues, and which is responsible for present-day relief. It accounts also for complexity of structure, notably in places where diapirism has occurred in anticlinal axes with extrusion of a bentonitic facies of the Wanstead Formation. Up to Middle Oligocene (Landon) time, however, Macpherson observes that the amplitude of anticlinal uplift was still small. “Elongated domes”, described by Lillie (1953, p. 85) as “ancestral” forms of “all the tectonic shapes of the region”, as seen in the present-day landforms, were thus in existence in embryo (and quite locally even closely folded) in the very early Notocenozoic, and they developed progressively, though their upheaval was accelerated considerably in late stages, especially where there are now ranges consisting of upheaved blocks, formerly anticlinal cores, of the pre-Notocenozoic undermass.
The argument for synchronous development of anticlines, as against sporadic folding, one rising here and one there at unrelated times, has been found by Macpherson in the presence, as proved by mapping over large areas of the geosynclinal belt, of recognizable lithologic units, or formations, each of which has been deposited in an interval of rest between spasms of folding. In an example from the Gisborne district that has been cited (Macpherson, 1946, p. 17) an unbroken succession of nine formations is present in synclines adjacent to an anticline in which they are separated by unconformities (Fig. 5). The succession is: lp, Lower Pliocene; a, Tokomaru Group (Upper Miocene); b, Tutamoe Group (Middle Miocene); c, Ihungia Group (Middle Miocene); d, Wheao Group (Late Oligocene-Lower Miocene), e, Weber Group (Oligocene); f, Waitangi bentonitic shale—including Wanstead (Late Cretaceous to Late Eocene); g, Whangara Shale (Late Cretaceous); h, Mangatu Series (Campanian). These rest on an oldrock basement in the core of the anticline, an embryo of which was developing already in the Late Cretaceous.
Recognition of the discontinuity of accumulation on progressively rising anticlines, with development there of some angular unconformities, while sedimentation was going on continuously in local minor geosynclines, explains some remarkable differences of geological interpretation. An example of such is afforded by comparison of two Geological Survey Bulletins, No. 9 (1910) and No. 21 (1920), both descriptive of the Gisborne district. In the earlier report unconformities
are net recognized, and the conclusion is reached (though it proves to be a mistaken one, based on non-discovery of fossil evidence to the contrary) that a sequence of strata many thousands of feet thick is Upper Miocene throughout. In the later report, however, emphasis is placed on the discovery in certain sections of unconformities within this sequence, in places strongly angular, which have been assumed to be of regional extent. Though the latter assumption may now be regarded as unwarranted, its adoption allowed the separation of a number of formations from one another, the ages of which, when dated on the evidence of a few fossils overlooked by the authors of the earlier report, have been found to range in age from Cretaceous to Pliocene.
Macpherson's principle is found to be applicable in other parts of the East Coast geosyncline also. Thus, Lillie (1951, p. 242) reports: “Localities of complete passage are concentrated on the margins of a major anticline in the centre of the Dannevirke Subdivision, while anticlines east and west give good evidence of non-sequences, unconformities, and clastic deposition in the late Cretaceous and early Tertiary.” To quote specific examples of contrasting columns not very far apart: Lillie, whose description and figure of the succession “in the Te Uri stream” (1953, p. 33) affords one of the most convincing demonstrations, in a North Island locality, of continuous accumulation in a minor geosyncline throughout a great part of Notocenozoic time, notes also (p. 83) the presence in the same (Dannevirke) district of a belt, the “Porangahau-Pourerere line of highs”, that was “often emergent” in early Tertiary ages and again later (at least once, in the Waitotaran age).
This pattern was not quite general, however. In the Tertiary geosynclinal belt west of and more or less parallel to the north-east-trending axis of the Southern Alps (in the South Island) it has been shown in studies by Gage (1949) and Wellman (1948) of parts of the Greymouth district that a geosyncline which developed in the early Tertiary (and probably earlier) along the line of the present-day coast was anticlinally upheaved and turned inside-out in or about Pareora (mid-Tertiary) times. Even in the East Coast geosyncline (of the North Island) sections across the Dannevirke district (Fig 6, after Lillie, 1953) show that a locus of early Notocenozoic sedimentation was upheaved anticlinally in
Text-Fig. 6.—Section across tihe Dannevirke district showing westward shift of the axis of sedimentation. Equivalence of formations: Raukumara. Clarence Series; Tapuwaeroa and Whangai, Mata Series; Wanstead (not shown). Teurian to Bortonian; Weber, post-Bortonian to Waitakian; Pareora Series missing; Thungin, lower Southland; Tutamoe, upper Southland; Mapiri, Taranaki Series; Mangatoro, Kapitean and Oportian; Te Aute, Waitotaran. (After Lillie.)
late Tertiary (Wanganui) time, when the axis of the trough of heavy sedimentation moved westward into the present-day tectonic lowland of southern Hawke's Bay.
The “Oamaru System” (Continued)
Five more stages of the Oamaru transgression have yet to be described.
The origin of the Duntroonian stage is to be found in a discovery by Allan (1938) that the “landonensis” fauna (index form: Liothyrella landonensis), believed by Thomson to be a facies faunule of the “Ototaran”, was of time significance, indicating a post-” Ototaran” (now post-Whaingaroan) age. Thomson had found this brachiopod fauna in beds 4.5 feet thick at Landon Creek, Oamaru, which has thus become the type locality for the Duntroonian. These beds have been shown by Allan to lie above the Upper Ototara bryozoan limestone, and to contain a fauna younger than any “Ototaran” (or Whaingaroan) fauna. The stage based on this type locality is named from Duntroon, North Otago, where also it is found as well as at a number of localities in South and North Canterbury.
Finlay (1939) regarded the horizon with this fauna as merely a basal zone of the Waitakian; but Finlay and Marwick (1940) restored it to stage rank. The brachiopod fauna includes; Liothyrella landonensis, Tegulorhynchia depressa. Murravia catenuliformis. Terebratulina suessi, and Stethothyris tapirina. Associated with the brachiopod fauna in glauconitic limestones and greensands in Otago, South Canterbury, and North Canterbury localities abundant and characteristic Foraminifera are found, which allow of correlation with the Chatton Sands formation, in Southland, and the Te Kuiti Limestone formation, of southern Auckland. In association with these at some localities there is a molluscan fauna in which a number of genera appear for the first time.
Finlay and Marwick (1940, p. 130) regard the Duntroonian as the opening age of a middle and later Tertiary era separated from the early Tertiary (largely Eocene) by a distinct faunal break. In North Canterbury this break coincides with the remarkable non-sequence or disconformity (described on p. 1089) between the Amuri Limestone and Weka Pass Stone formations (Whaingaroan and Duntroonion respectively), a break that, has been claimed by some geologists as one between Cretaceous and mid-Tertiary.
It may seem strange to find the Whaingaroan and Duntroonian grouped in the same series (Landon) in the Geological Survey classification; but a reason for this may be found in the apparently Oligocene age of the Whaingaroan, which has led to its detachment from the Middle to Upper Eocene Arnold Series. The establishment of a faunal break of some importance and the appearance of physical disconformity (even if this is only local) may be claimed, however, as justification for introducing between descriptions of the Whaingaroan and Duntroonian stages the long digression in which some phases of early Tertiary history have been reviewed (pp 1099–1105).
The name Waitakian was introduced for a stage by Park (1918); but Park believed the stage should be correlated with a molluscan fossiliferous horizon at the top of the Hutchinsonian as developed in the Oamaru coastal district, and so
he called it also Upper Hutchinsonian. Allan (1933) has shown, however, that this correlation was a mistaken one, and that the place of the Waitakian is below the Hutchinsonian, such being the stratigraphical order of the type beds of the Waitekian in the Waitaki Valley, North Otago; these are the Waitaki Limestone together with overlying Otiake Beds.
The age of the limestone facies in this western (inland) locality is younger than that of the Ototara Limestone of the eastern (seaward) margin of the Oamaru district, which is “Ototaran”, or Kaiatan-Runangan-Whaingaroan; but it is not so much younger as to make it post-Hutchinsonian, as Park supposed, or even Hutchinsonian. Its age is, however, separated from Whaingaroan by the Duntroonian.
Though the Ototara and Waitaki Limestones are not found anywhere in contact, it appears that they have been in the past lithologically continuous. This relation, or apparent relation, led to a long controversy as to whether they were parts of one continuous stratum (“one-limestone theory”) or represented two horizons of limestone facies that might yet be found somewhere in sequence (''two-limestones theory”); but this was argued as though it were a question of whether or not they were of the same age. The verdict of Allan (1933) is that the two-limestones theory has prevailed. This does not mean, however, that they were deposited at times of maximum submergence in successive cycles of sedimentation; but rather it appears that in a single transgression the limestone-making facies of off-shore organic sedimentation was migrating westward through the course of several ages.
In the sections of the coastal (Oamaru) district the place of the Duntroonian, Waitikian, and Otaian stages is taken by a non-sequence—a diastem—as though no sedimentation had taken place during all this time.
The type section selected by Allan (1933) for the Waitakian is that at Trig. Z, Otiake, of which a section was shown by Uttley (1920). In this section an Otekaike Limestone (local name for Waitaki Limestone) is followed by Otiake Beds (glauconitic, calcareous, and sandy). These overlie a greensand with the Duntroonian microfauna and (not far away) its brachiopod fauna. The limestone, which is sandy and about 150 feet thick, contains a brachiopod fauna distinct from that of the Duntroonian below and from one of Hutchinsonian age in higher beds. It is characterized by species of the Pachymagas huttoni “series”, whereas those of the Pachymagas parki “series”, characteristic of the Hutchinsonian, are conspicuously absent. In the Otiake Beds molluscs are abundant, which differ in species from the preceding and succeeding stages. Foraminifera are present, but seem less distinctive than the brachiopods and molluscs.
The Otaian stage was introduced between Waitakian and Hutchinsonian by Finlay and Marwick (1947) because of the intercalation of a distinct fauna between those recognized (below) as Waitakian and (above) as Hutchinsonian in a continuous section at Blue Cliffs, Otaio River. South Canterbury. “The type Otaian extends from somewhat below the middle of the banded beds at Blue Cliffs eastward to past the Southburn Road and up to the ‘Brown Sandstone’, which is Hutchinsonian”. This includes most of the outcrops yielding molluscan fossils at Blue Cliffs.
Both foraminiferal and molluscan faunas are characteristic, and the latter includes several species peculiar to this stage, while a number of species make their first appearance in it. In some sections Otaian Foraminifera allow three zones to be distinguished.
Otaian age is established by foraminiferal evidence for the formation known to early geologists, and frequently referred to, as the Grey Marls in the clearly exposed Waipara Gorge and Weka Pass sections of North Canterbury (Geol. Survey, 1948, p. 34). These are the sections which, beginning with Piripauan, followed by greensands, which are Cretaceous-Tertiary passage beds, and by Bortonian, continue through Amuri Limestone and the closely associated Weka Pass Stone formations (Whaingaroan–Duntroonian–Waitakian in age) and then the Otaian of the Grey Marls formation to some higher stages without any angular discordance and with but few indications of physical breaks (Fig. 4).
One of the remaining two of Thomson's original stages based on formations known at localities near Oamaru (Hutchinsonian and Awamoan), the Hutchinsonian is named from the Hutchinson's Quarry Beds, a glauconitic horizon at the early-known collecting locality Hutchinson's Quarry, in the town of Oamaru.
The Otaian, Waitakian, and Duntroonian stages being missing, the Hutchinsonian here rests with some measure of unconformity or non-sequence, though without any angular discordance, on glauconitic limestone and tuff beds of the Ototara Limestone formation. This does not seem to have resulted from emergence, but more likely from complete failure of the supply of terrigenous sediment; for at this time—specifically Duntroonian and Waitakian— “the greater part of New Zealand was submerged; a possible exceptional area is Central Otago” (Suggate, 1952, p. 109). According to Wellman (1953, p. 38), subsidence ceased for a considerable time (in South Canterbury) and, the bottom being swept clean by currents, conditions favoured the formation of glauconite.
Hutchinsonian calcareous greensands, which are found thus to overlie the Ototara Limestone in various sections near Oamaru, are generally crowded with brachiopods near the base. The basal layer is phosphatized at Hutchinson's Quarry and in other Oamaru sections, and this, together with the abrupt change of lithological facies, led Thomson to adopt the explanation that there had been cessation of deposition, though he did not realize that it was necessary thus to account for a gap amounting to the duration of three ages (Duntroonian to Otaian).
The lower limit of the Hutchinsonian cannot be defined in terms of the fauna of the type section; other greensands overlying the Kakanui Limestone (Whaingaroan) with a similar appearance of discordance contain towards their base some brachiopods considered older than any in the basal bed at the Hutchinson's Quarry, apparently because of overlap. These greensands, also referred to the Hutchinsonian stage, are fossiliferous in several well-known collecting localities: Rifle Butts, Kakahu, Devil's Bridge, All Day Bay, and Deborah. As a temporary definition to include these, pending more precise definition based on detailed study, Allan (1933) has suggested that the Hutchinsonian age may be defined as “the period of time during which the Pachymagas parki series of brachiopods were the characteristic fossils”. This allows also the inclusion of the main limestone horizon in the Mount Brown Beds of the Waipara section
(Fig. 4), fossiliferous limestones at Winton and Clifden, Southland, and the long-known collecting locality Curiosity Shop, in a small inlier of Tertiary rock surrounded by the thick gravels of the Canterbury Plain where these are deeply trenched by the Rakaia River.
The stage being thus defined paleontologically, Allan found it divisible on a faunal basis, as follows: (a) (oldest) a brachiopod faunule, the Liothyrella boehmi assemblage characteristic of the basal phosphatic horizons in the Oamaru coastal district; (b) the Pachymagas parki assemblage, found in the greensand of Hutchinson's Quarry, in the Mount Brown Limestone, and in the Clifden Limestone; (c) the Pachymagas hectori assemblage, restricted to the greensands of Deborah, Rifle Butts, Devil's Bridge, and some other localities in the Oamaru coastal district; and (d) a molluscan faunule known only from beds stratigraphically above the brachiopod-bearing greensand at Hutchinson's Quarry outcropping in the nearby locality Target Gully, but below the beds of Awamoan age known as Target Gully Beds.
More recently Finlay (1939, p. 530) has suggested separation of the earlier from the “true” Hutchinsonian (that of the type section). Though no new name has been proposed for this subdivision, Finlay and Marwick (1940) have listed its fauna separately as Lower Hutchinsonian. Basing a distinction on the brachiopods, they have found that more advanced forms of certain species of Pachymagas and Rhizothyris are present in the “true” Hutchinsonian but absent from the lower division—as also is the genus Waiparia s. str, which came in after the extinction of Pachymagas and Rhizothyris.
In the All Day Bay section the horizon (Lower Hutchinsonian) containing only the less advanced brachiopods, including Pachymagas marshalli, and a basal phosphatic horizon with the corals Isis and Mopsea, rest on “eroded Kakanui Limestone”, and over this is sandstone with the brachiopod genus Waiparia but no longer any species of Pachymagas. This continues up to the base of the Awamoan.
The division (d) of Allan, with a molluscan faunule that is not well known, is based on a bed discovered by Park and found to contain a pre-Awamoan fauna. It is beneath the better known, richly fossiliferous. Target Gully shell bed, which is Awamoan. This is the Upper Hutchinsonian of Park, with which he erroneously correlated the Waitakian.
By means of Waiparia, a brachiopod genus of restricted time range, the upper division, or “true” Hutchinsonian, of the All Day Bay and similar sections has been correlated (by Finlay and Marwick, 1940) with the sandy and calcareous Mount Brown Beds of North Canterbury and the Caversham Sandstone, at Dunedin, thus allowing correlation also with their good foraminiferal faunas and making these available to supplement the more scanty microfaunal record in intercalated layers in the type section.
Another supposed Waiparia correlation (Finlay and Marwick, 1940) with a brachiopod-bearing horizon of the Middle Ihungia Formation, in the Gisborne district, of the North Island, has been abandoned, the whole Ihungia Formation being now regarded as much younger than Hutchinsonian (Geol. Survey, 1948, p. 28). Unconformity between Landon and Southland Series in that district (Geol. Survey, 1948, p. 28) is consistent with a theory of emergence of all or part of the North Island East Coast region in the Pareora epoch (Lillie, 1953, p. 79), making a Hutchinsonian correlation improbable.
Lists of molluscan fossils for Hutchinsonian correlation were compiled by Finlay and Marwick (1940) from various localities, but, as the formations formerly regarded as Hutchinsonian, which yield these molluscs, are now in great part referred to stages of a younger (Southland) series, the lists are subject to revision; and little is really known of the molluscan life of the Hutchinsonian. One important section, that at Clifden, Southland, formerly regarded as largely Hutchinsonian, and comprising a sequence of beds with molluscan fossils overlying limestone formerly believed to contain the Hutchinsonian Pachymagas parki assemblage of brachiopods, is now adopted as the type section for the Southland Series. Here a limestone stratum now regarded as of Otaian age is followed unconformably (after a basal pebble zone) by another limestone of the Southland Series, both the Hutchinsonian and Awamoan being missing from the section.
The Awamoan stage is another of the last two survivors of the stages first recognized by Thomson in the “Oamaru” group (now divided into Arnold. Landon, and Pareora Series). It is the last stage of the Pareora Series. The formation known as Awamoa Beds, containing the only richly fossiliferous strata yielding molluscs in the Oamaru coastal district, furnished the bulk of the “Oamaru” molluscan fauna known to early New Zealand geologists. The richness of this fauna led to mistaken correlation with it of other smaller faunas collected from formations in other parts of New Zealand, most of which are now recognized as younger and are referred to the Southland Series. Shorn of these, the distribution of the Awamoan is now restricted almost to the district immediately around the type section, though, prior to 1947, the Awamoan appeared, according to the information that had been made public, to be of wide distribution.
Traced upward in various sections exposed near Oamaru, the Hutchinsonian greensands pass into shelly sands and blue sandy mudstones of the Awamoa Formation, which gives its name to the stage. In the adjacent South Canterbury district, beds of this stage with similar facies have been known as Mount Harris Beds. These formations, indicative of shallowing seas and an increasing supply of terrigenous waste in a regressive phase following the Oamaru transgression, are fossiliferous in many outcrops. One of these, recognized by Finlay and Marwick (1940) as the type locality originally selected by Thomson for the stage is in Awamoa Creek, near Oamaru. Allan records, however, that the Awamoan section is more clearly exposed at an adjacent locality, Rifle Butts, where the Awamoa Beds conformably overlie Hutchinsonian greensand with Pachymagas parki, passing up through glauconitic sandy shell beds to blue sandy clays with a few thin hard-sandstone intercalations, the total thickness being about 100 feet.
The basal molluscan shell bed in this section (outcropping at Ardgowan also) is recognized as correlative with the richly fossiliferous Target Gully shell bed, adjoining Hutchinson's Quarry; and this faunal community is distinct in some respects from that of the blue clays higher in the Rifle Butts and Awamoa Creek sections, which also yield fewer species.
Brachiopods had become rare; but Foraminifera were abundant.
Supposed correlations of the Awamoan throughout New Zealand, as listed by Finlay and Marwick (1940), are, with the exception of a few outcrops in South
and North Canterbury, now regarded as younger, being referred to the Southland Series.
Restricted Occurrence of the Pareora Series
It would appear that though in one district, Southland, limestone was accumulating in the Otaian age, and in others, South Auckland and North Nelson, a Waitakian limestone facies of deposit had been succeeded in the Otaian by a glauconitic facies, during the Hutchinsonian and Awamoan ages there was practically no sedimentation outside a belt extending from North Otago to North Canterbury. The Pareora epoch does not, however, seem to have been a time of conspicuous emergence of any part of the New Zealand region, as is proved for the hinterland of the Oamaru district by the glauconitic-calcareous facies of the Otaian and Hutchinsonian sediments there; but the Hutchinsonian is represented by a thicker sandy-calcareous facies farther north, and even in the Otaian age thick mudstone had accumulated at Mokau River, in the South Auckland district. The opinion of Lillie (1951) that “late Oligocene … fold movement” must have been “considerable” has been already noted (p. 1102).
Change of facies to mudstone in the Awamoan at Oamaru, though the thickness of accumulation was not great, also suggests some local upheaval in progress in Pareora times, foreshadowing the close of the anorogenic “Oamaru” period, which was to be followed by a long interval not represented by sediments, marine or other, in the Oamaru-South Canterbury district.
End of the “Oamaru” Period
So ended the “Oamaru” period of New Zealand geology, a natural one corresponding to a protracted cycle of sedimentation comprising the three epochs Arnold, Landon, and Pareora of the arbitrary classification which dispenses with the “Oamaru” period. Such rejection is consistent with the scheme adopted by the New Zealand Geological Survey, which divides the Tertiary into series, not systems. The time range of Oamaru sedimentation extends through most of Eocene and Oligocene time—specifically from Lutetian to Chattian, according to foraminiferal correlations made by Finlay (1947, p. 352).
Another reason that might be urged in support of the change of nomenclature is difference of facies between correlative formations of some other parts of New Zealand and those of the Oamaru district. There is some appearance of disharmony in the extensive sedimentary province in the East Coast geosyncline of the North Island with the lithological sequence of the Oamaru and some other more or less similar sections in which transgression culminated at some stage of the “Oamaru” period with the production of an open-water limestone, followed by regressive sedimentation. This may, however, be more apparent than real. In the sedimentary fill of the East Coast geosyncline a true limestone facies is absent or very uncommon throughout the long sequence of stages from Upper Cretaceous through Paleocene to the early or middle Oligocene Landon epoch, but there is an approach to this facies in calcareous mudstones of Landon age termed the Mangatu Formation, in the Gisborne district, and Weber Formation, in southern Hawke's Bay (Geol. Survey, 1948, p. 271). Mudstone, in places thick and rather a siltstone and in other places much thinner and glauconitic, is the prevailing facies. On the whole, the open-sea sedimentation conditions indicated are comparable to those prevailing in the Oamaru district modified only by
comparative nearness to sources yielding terrigenous sediment in considerable quantity; and the same may be said of the western part of North Auckland.
In the West Coast districts of the South Island differences from the Oamaru district type of sedimentation are attributable to the development of another (smaller) geosyncline, about 10,000 feet deep, in the Arnold epoch, and the availability of abundant terrigenous sediment to fill it (Wellman, 1948; Gage, 1949). Even the Cobden Limestone formation (Whaingaroan to Waitakian in age) is nearly 1,000 feet thick in the Greymouth district. An even greater thickness of the Amuri Limestone formation in the north-eastern part of the South Island has already been mentioned (p. 1088).
One feature giving rise to apparent dissimilarity of sequences referable to the sedimentation cycle of the “Oamaru” period is the delayed initiation of the transgression in some districts, which has led to wide overlap.
This series is represented in Southland by a sequence of strata about 1,200 feet thick. All four stages (Altonian, Clifdenian, Lillburnian, and Waiauan) of the Southland Series have their type locality in the section exposed along the bank of the Waiau River at Clifden, Southland, in strata formerly regarded as for the most part Hutchinsonian passing up into Awamoan. Finlay and Marwick (1947) have reported their discovery that, whereas the lower part of the limestone outcropping in this section (with total thickness of 600 feet) may be referred to the (new) Otaian stage there is a hiatus in the middle of the limestone stratum, so that the Hutchinsonian and Awamoan stages are not represented, the Upper Oligocene having been a time of non-deposition. Sedimentation began again early in the Miocene, and the upper 300 feet of the limestone (separated from the Otaian portion by a pebble zone) are referred to the Altonian stage of the Southland Series together with “overlying quartz sands and argillaceous sandstone” with “mollusc and foram faunas” (Finlay and Marwick).
Text-Fig. 7.—Section in the bank of the Waiau River, at Clifden. Southland, type locality of stages of the Southland Series. (After Park.)
The section (Fig. 7) on which this observation is based is that described by Park (1921). The lowest bed, numbered (1) by Park, is the thick polyzoan limestone that is in part Otaian and in part Altonian. Those that follow are described as: (2) calcareous sandstone (glauconitic); (3) sandy clays with molluscan fossils; (4) thin-bedded sands and clays, with few molluscs; (5) blue clays with Foraminifera; (6a, 6b, 6c) sandy clays, richly fossiliferous; (7) marly shelly sands, fossiliferous; (8) sandy clays, fossiliferous.
In addition to the upper limestone beds 2 to 6b are referred to the Altonian. They contain warm-water molluscan shells and a foraminiferal fauna of warm-
water genera, notably orbitoids, which are more abundant in this stage than in any other and indicate Aquitanian age. The stage is marked by the first appearance of a number of molluscan genera and of many species, and there is some recurrence of genera absent from—or at least not known in—the Awamoan. Numerous genera are peculiar to the Altonian. The foraminiferal fauna of bed 6b is transitional to the next stage, Clifdenian.
The type section comprises only the thin bed 6c in the Clifden section. The chief faunal characteristic is the “spectacular” entry of Orbulina, which is found throughout New Zealand, being “checked from numerous sections”, to be “a faunal feature of major significance” (Finlay and Marwick, 1947). In other sections (in the Blue Bottom formation, in Westland, and in the Ihungia Formation, in the Gisborne district), where the facies of deposit is more muddy, numerous species of other genera make their first appearance along with Orbulina. The molluscan fauna is marked by the last appearance of several genera and first, appearance of others.
In the type section at Clifden, the Lillburnian stage “corresponds approximately to Park's bed 7”. Definite changes in foraminiferal and molluscan faunas mark off this stage from those below and above in the type section; and elsewhere, where more richly fossiliferous, the stage is marked by the first appearance of several for aminiferal as well as a number of molluscan species; and one molluscan genus and several species come to the end of their range.
An important section, that at Muddy Creek, in the Gisborne district of the North Island, is cited for comparison by Finlay and Marwick (1947), who regard it as a “standard section”. But for the clearness of the succession at Clifden, showing the relation of the Lillburnian to lower and higher stages of the Southland Series, the Muddy Creek section might appropriately have been chosen as the type section for the stage. In it the more muddy facies accounts for the presence of certain lineages of both macrofossils and Foraminifera not found at Clifden. All the stages of the Southland Series are represented in the Muddy Creek section in beds of the thick Ihungia and Tutamoe formations; but fossils are scarce below and above the Lillburnian. The upper part of the Ihungia Formation, as mapped by the Geological Survey, is Clifdenian. (as indicated by its microfauna). This is followed by Lillburnian, represented by the lower part of the Tutamoe Formation as mapped, including basal conglomerate. The Upper Tutamoe, which follows, has Waiauan microfannas.
In the Clifden section, the Waiauan “corresponds approximately to Park's bed 8” (Finlay and Marwick, 1947), which consists of shelly sand. Above this, but not shown in Fig. 7, the lowest stage of the Taranaki Series is present, following the Waiauan apparently in unbroken sequence. There are characteristic Waiauan Foraminifera in the type section; the molluscan fauna has several species restricted to it, and several species make their first and others their last appearance.
The Waiauan is found at various localities in both South and North Islands. Finlay tnd Marwick (1947) report that “in a number of places it transgresses on to considerably older beds, while in other places it occurs as the end member
of a long stretch of conformable beds”. At a few places it is followed conformably by beds of the Taranaki Series.
Regional Distribution of the Southland Series
There was wide submergence in the Southland epoch (Lower and Middle Miocene), but this was not general throughout the region. Though in the preceding (Pareora) epoch there had been little or no sedimentation outside some eastern districts of the South Island there had been no general orogeny, emergence accompanying which would have definitely separated a later from the earlier Tertiary (“Oamaru”) transgression, or cycle of sedimentation. The Oamaru-Canterbury belt was still subject to sedimentation in the Pareora epoch; but it later became sufficiently positive to escape Southland sedimentation.
In other extensive areas, which were submerged and subject to marine sedimentation in Southland time, transgression had begun earlier, in some cases in the Otaian and in other cases still earlier, the Hutchinsonian-Awamoan hiatus being an obscure disconformity. This is the case in North Auckland, where one of the richest deposits of Altonian molluscs and Foraminifera has been found (at Pakaurangi Point, Kaipara Harbour).
In South Auckland, where marine transgression took place in the Whaingaroan age over a low-lying land already mantled with the Huntly Coal Measures, the Whaingaroan is followed by the Te Kuiti Limestone formation, of Duntroonian–Waitakian age. which overlaps the Whaingaroan on to an oldrock floor. Mudstone of Otaian age (the Mahoenui Formation) follows the limestone and thickens southward; but beyond this there is a break indicative of non-deposition of marine sediments (possibly due to a Hutchinsonian-Awamoan emergence), though there was perhaps fresh-water accumulation in Pareora times in the Mokau River basin, where there are coal measures. In this Mokau River area marine sedimentation began again in the Southland epoch.
Farther south, in Taranaki and western Wellington, Southland and older strata, if present, are hidden under the thick and gently inclined younger Tertiary formations (of the Taranaki and Wanganui series).
In the eastern districts of the North Island, absence of Hutchinsonian and Awamoan seems to indicate some emergence at this time, which was followed, however, by heavy sedimentation in the Southland epoch, giving thicknesses up to 10,000 feet. Geosynclinal subsidence took place on certain axes, between which were permanent or persistent highs that have already been referred to, with “thinning out, unconformities, and missing beds on the flanks” (Geol. Survey, 1948. p. 28). Formations mapped in these districts that are of Southland age are the Ihungia and Tutamoe. The Ihungia Formation, together with the locally thick Wheao Formation under it, have been shown by microfaunal evidence to be Altonian and Clifdenian; the Tutamoe Formation is Lillbnrnian and Waiauan (Waiauan microfaunas being most widely present in it, though a Lillburnian horizon is known to be present in the Muddy Creek section at least). In the Tutamoe Formation an alternate banding of thin sandstone and mudstone layers is commonly found.
Henderson (1929, p. 294) regarded the geosynclinal development of the eastern districts of the North Island as a “new cycle of deformation”. He wrote “The extensive post-Ototaran [really post-Pareora] overlap of the
Tertiary rocks on the older mass … may be interpreted as supporting this conclusion…. The deposits throughout this region are enormously thick compared with contemporaneous beds elsewhere, they are predominantly terrigenous, and they are of shallow-water origin from top to bottom…. A geosynclinal trough was forming and being filled in this region, whereas … in its southern portion the New Zealand area was intermittently and progressively rising.”
In the South Island, apart from Southland, the Southland Series is developed on the West Coast and in the north-eastern district. In the latter it follows on, without discordance or the appearance of a physical break, after a profound non-sequence a little above the Amuri Limestone formation. This is indicated by the presence of foraminiferal evidence of Clifdenian age in the basal part of a marl formation 600 feet thick that is probably of Southland age throughout.
Overlap took place in later Southland time across northern Marlborough, where transgression submerged a floor that had been developed by erosion across pre-Notocenozoic greywackes, and where geosynclinal sinking and accumulation were to continue through the latter part of Tertiary time.
West of the Southern Alps, there is geosynclinal development of the Southland Series 12,000 feet thick in the Murchison basin; and the Blue Bottom formation, of Westland, which consists of mudstone and is 1,500 feet thick, includes beds referred to each of the Southland stages; these indicate continuous accumulation. Drilling has revealed the presence of the series also in the deeper part of a thick fill of silty mudstones in the narrow geosyncline under a tectonic lowland forming the Grey Valley. This is separated from the more ancient geosyncline of the Greymouth Coalfield, with its fill of pre-Tertiary (Paparoa) and Eocene (Brunner) coal measures, by the positive Paparoa Range and Brunner Anticline (Fig. 8). The shifting here of an axis of geosynclinal accumulation eastward (described by Gage, 1949) is comparable to the westward shift in the Dannevirke district (compare Fig. 6).
Two stages, Tongaporutuan and Kapitean, both of Upper Miocene age, are assigned to this series. Publication of a Geological Survey Bulletin (Grange, 1927) describing a district in North Taranaki, showed the necessity for recognition of stages to include formations outcropping in Taranaki stratigraphically above those which, though now placed in the Southland Series, were formerly
Text-Fig. S.—Section across the Greymouth district, showing how thick marine sedimentation (in Southland and later epochs) has followed an eastward shift of a geosynclinal axis. Equivalence of marine formations: Lower Marine Group, Bortonian to Waitakian; Upper Tertiary Group, Altonian to Waitotaran, (After Gage, 1952.)
thought to be Awamoan, and below the already known Wanganui Series, in which Thomson had defined the types of two stages. The state of knowledge of the-upper Tertiary at the time Thomson (1916) first defined Tertiary stages was:
Top of “Oamaru” group of series.
Other stages probable Awamoan.
The gap below the Wanganui Series was partly filled by recognition of the Taranaki Series; and much later most of the supposed Awamoan was transferred to the new Southland Series.
The two divisions of the Taranaki Series at first defined by Grange (1927) were termed Tongaporutu and Urenui formations (as they may now be called). Beds mainly of the Tongaporutu Formation, as then defined, have become the type of a Tongaporutuan stage; but the second stage of the Taranaki Series, the Kapitean, has for its type a formation not in Taranaki but at a locality on the West Coast of the South Island, as defined by Finlay and Marwick (1947) who have introduced this stage name.
Rejection of Urenuian as a stage name applicable to beds in the upper part of the Taranaki Series was suggested by Allan (1933), who found the molluscan fauna of the Urenui Formation to differ very little from that of the Tongaporutuan. Allan did, however, find the fauna of the Taranaki Series as a whole to be so distinctive that he predicted probable discovery of another stage or stages between the Taranaki formations as then known and the Wanganui Series, just as it seemed necessary also to fill a gap below the Taranaki Series, as has been since done by establishing the four stages of the Southland Series.
On the basis of microfaunas described by Finlay (1939) Urenuian and Tongaporutuan stages, as they had been previously defined, were merged as a single “Taranakian” stage; but in the following year (Finlay and Marwick, 1940) the names Tongaporutuan and Urenuian were revived. The revival of “Urenuian” was only temporary, however. Distinction between the Tongaporutuan and a stage following it could not be made satisfactorily in the Urenui locality (Urenui Formation); but beds above those referable to the Tongaporutuan stage in other districts were found to contain a distinctive microfauna, with the result that the upper stage of the Taranaki Series received the name Kapitean, taken from a locality in Westland yielding a good microfauna (Finlay and Marwick, 1947).
The Taranaki Series follows the Southland Series with apparent conformity in the South Auckland (Mokau River) district; and it is thick in North Taranaki, where 3,000 feet of beds, of the Tongaporutuan stage, are exposed in the coastal section. These are argillaceous and silty mudstones with layers containing calcareous concretions. Conglomerate beds and local unconformity separate this lower part of the series from an upper portion (the Urenui Formation), but this also is now regarded as referable to the Tongaporutuan stage because of faunal similarity. The next stage, Kapitean, is known to be present in eastern Taranaki.
Though not reported in North Auckland, middle and South Canterbury, or Otago districts, which seem to have been emergent in the Taranaki epoch, this series is present in most other parts of New Zealand, being generally represented by a silty mudstone or sandstone facies. It is largely developed in the East
Coast belt of the North Island, where it is in many places unconformable on formations of all ages up to Southland, though it overlies the Southland conformably in axial parts of the East Coast geosyncline. In northern Hawke's Bay the series is 12,000 feet thick, outcropping in a broad eastward-dipping homoclinal belt from Waikaremoana to the coast at Wairoa. Sandstone of the Taranaki Series is exposed in cliffs at the eastern end of the head of Palliser Bay, being there unconformable on the deformed pre-Notocenozoic rocks of the Haurangi Range and having very thick conglomerate at its base. South of this, in the Awatere Valley, South Island, there are similar, but thicker, formations. In Southland there is another thick development, associated with the Southland Series. Both the stages are represented on the West Coast of the South Island, being present in the Blue Bottom formation, which is in part also of Southland age, and in the upper half of the fill (8,000 feet thick) in the Grey Valley geosyncline (Fig. 8).
The type locality of the Tongaporutuan stage is on the coast at Tongaporutu, North Taranaki.
As defined by Finlay and Marwick (1947), the type beds of the Kapitean stage are at Kapitea Creek, Westland, where beds with a characteristic fauna are distinguished from underlying Tongaporutuan mudstone that also contains a rich fauna. The Kapitean part of the section consists of greensand followed by argillaceous sandstone; and without lithological break the Taranaki Series passes up into the Wanganui Series. Besides distinctive Foraminifera, the type section yields a molluscan fauna containing a characteristic species (Austrofusus tuberculatus) and the last New Zealand appearance of Cucullaea.
The Wanganui Series has sometimes been conventionally regarded as coextensive with the Pliocene. As regards the upper, or Pliocene-Pleistocene, boundary in particular, it is now generally agreed that the boundary is not above but within the Wanganui Series, though it has not yet been established how far down this is to be placed.
Such a view was foreshadowed by Hutton (1875, p. 83), when he placed the New Zealand ice age in the Lower Pliocene (it having been caused, in his opinion, by regional elevation) and the marine formations of the Wanganui Series in the Upper Pliocene and Pleistocene. No other geologists have closely followed Hutton in this dating of the glaciation, but there is no doubt that some of the evidence Hutton relied on has a bearing on the problem of the Pliocene-Pleistocene boundary.
Marwick (1934, p. 959) also states: “No clear evidence has yet been put forward to show that the Wanganui beds, from Patea to Castlecliff, represent only the Pliocene and that the glaciation took place after these beds were laid down. In view of the uncertainty about the Pliocene-Pleistocene boundary in Europe, where mammalian remains afford such valuable criteria, we need not expect a definite boundary to be drawn in New Zealand. At the present the Pliocene is defined by marine strata and the Pleistocene in general by terrestrial deposits and raised beaches.” More recent studies indicate, however, that changes of climate are proved by faunal changes in the upper part of the Wanganui Series
of marine strata, changes which ought perhaps to be correlated with glacial and interglacial ages in the Pleistocene. Fleming (1944) has reported evidence of an invasion of the shallow seas of the North Island geosynclinal basins, by very cold water in the Nukumaruan age, as indicated by the appearance of a number of molluscan species with Subantarctic affinities—notably Chlamys delicatula and Tawera subsulcata—which do not persist into the next stage. He has suggested correlation of this cold phase with the earliest Pleistocene ice age (Fleming, 1953); and, moreover, glacial deposits of probably Nukumaruan age have been reported at Ross, Westland, by Gage (1945). This would make the whole of the Castlecliffian and part of the Nukumaruan Pleistocene; and the freshness of the marine molluscan remains in the upper beds of the series locally thousands of feet thick (Te Punga, 1952b) suggests for these an age measurable only in thousands of years.
Just as the Notocenozoic major marine cycle of sedimentation began at widely different times in different parts of tihs region, and just as it was interrupted nearly everywhere more than once, and very many times in the parts that became persistent “highs”, so it was brought to a close by emergence at various times in various districts. Thus, the Oamaru-South Canterbury marine succession closes with the Awamoan, few parts of the South Island (except the northeast corner) were submerged in the Wanganui epoch, and in North Auckland the Kaikoura orogeny, which Thomson pictured as closing the era, took place as remotely as the Southland epoch, for upper Southland stages as well as those of the Taranaki and Wanganui series seem to be absent from that extensive district (Geol. Survey, 1948, p. 29).
It was suggested by Henderson (1929, p. 294) that all beds referable to the Castlecliffian stage were of later date than the Kaikoura orogeny, so that they would have to be classed as post-Notocenozoic if Thomson's definition were to be strictly applied. According to his view, however, “the main differential movements of the Kaikoura orogeny”, though they “began in Nukumaruan time, … continued after it” also. Some non-marine conglomerate formations in the South Island accumulated at this time; “but great movements continued after their deposition, and the climacteric deformation was later” (Henderson, 1929, p. 297).
Apart from small local developments marginal to land that still exists, the Wanganui Series is confined to a few geosynclinal areas. These, and also some marginal submergences in the early part of the epoch, are shown on a paleogeographic map by Fleming (1949). The largest geosynclines were respectively east and west of the (then low but partly emergent) axial range of the southern part of the North Island (Tararua-Ruahine Range), and the eastern one extends farther north-eastward across Hawke's Bay. There was also a smaller area of thick sedimentation in the Awatere-Cape Campbell district, in the north-east of the South Island.
These geosynclines developed only in very late Tertiary time, and the Wanganui strata in them overlap widely on to the pre-Notocenozoic basement rocks, especially in the North Island, where widespread thinner strata of Waitotaran and Nukumaruan age, including extensive shell-limestone formations, lap over on to a planed surface truncating the old rocks of the axial range, notably west of Napier, from which the cover is now being stripped away by erosion so as to expose the fossil peneplain at an altitude of 3,000 feet.
In the western (North Island) geosyncline and in the northern part of the eastern one clastic sediments accumulated to a thickness of many thousands of feet, these being derived in part from the axial ranges, which must have undergone progressive uplift and erosion at this time, but in part also from other land areas consisting of both Notocenozoic and older rocks. In the middle of Wauganui time the facies of deposit changed in eastern districts to shell limestone of shallow water origin.
The earliest known beds with the fauna of the Opoitian stage are those of the Kaawa Formation, which outcrops on the west coast of the North Island south of Waikato Heads, and seems to represent a small marginal transgression over an otherwise emergent region. These beds are of historical interest, as they were the first to be definitely assigned to the previously unfilled Awamoan-Wanganui interval. The type of the Opoitian stage is, however, the Opoiti Formation, in northern Hawke's Bay, which consists of a sequence of argillaceous sandstones and tuffs 4,000 feet thick, lying disconformably on the Mapiri Mudstone formation, of Taranaki age, and covered unconformably by strata referred to the Waitotaran stage. In these beds there is an abundant and characteristic foraminiferal fauna, with also molluscs and some brachiopods (species of Neothyris). Formations in various parts of New Zealand are correlated with the Opoitian— eg., tie Kaawa beds, mentioned above; the top of the Blue Bottom formation, of Wetland, lower parts of which are referred to the Southland and Taranaki series; and also some beds in the Gisborne district and in Taranaki.
This stage and the Castlecliffian are the two which were first defined (Thomson, 1916) in the Wanganui Series. Between these a Nukumaruan stage was introduced by Morgan (1924), who was followed by Allan (1933). Thomson based his stages on the coast section of western Wellington, from Wanganui northward to Waipipi, where 3,450 feet of beds are exposed, all dipping gently southward These are mostly blue sandy mudstones and sands. Thomson relied on an earlier description of this coast section by Park; but the section was later re-examined by Marshall and Murdoch (1920, 1921), and still later detailed work by the Geological Survey has linked up the coast section with sections farther north that expose the Taranaki Series sufficiently to show that there is no marked stratigraphical discordance between the series. At one inland locality, however. Waitotaran beds are reported to rest on an eroded surface truncating beds regarded as part of the Urenui Formation. Possibly the Opoitian is missing there.
The Waitotaran is known to extend far inland, and its thickness is estimated as 3,250 feet, in the belt that reaches the coast north of Wanganui. In addition to sandstones argillaceous sandstones, and mudstones pebble beds are reported, and also thin irregular beds of shell limestone. Tuff is reported in some of the sandstone layers.
A thicker section (14,000 feet) of Waitotaran, Nukumaruan, and Castlecliffian is reported by Te Punga (1952a) exposed along the banks of the Rangitikei River, which follows more or less closely the axis of a local geosynclinal basin. Eastward, towards the Ruahine Range, the Waitotaran lies unconformably on the pre-Notocenozoic basement, the floor and basal beds dipping westward at about 10°; but in the higher stages, farther from the range in the Rangitikei section,
the dip diminishes. The lithology is similar in a general way to that of the Wanganui coast section, shallow-water beds predominating.
For the Nukumaruan and Castlecliffian stages in the type (coastal) localities north of Wanganui descriptions by Fleming (1947; 1953) are available, giving much detailed information. The Nukumaruan stage was introduced by Morgan (1924) after the publication of studies by Marshall and Murdoch (1920; 1921). The type locality is now defined (Allan, 1933; Finlay and Marwick, 1940) as the Nukumaru coast, west of “Wanganui, the fauna being that in the Nukumaru Formation (or “series”) as first listed by Marshall and Murdoch and later by Marwick. Correlation is made mainly by the molluscan fauna, but Foraminifera are present (though those of muddy or deep-water facies are not known). The thickness in the coast section is only about 400 feet, mainly sands and silts of shallow-water and beach origin, including 100 feet of shell limestone at the base, and with several intercalations of non-marine beds (sands, fossil soils, and lignites). In the Rangitikei River section (Te Punga, 1952a), there is a much greater thickness of shallow-water marine beds (4,000 feet).
The type locality of the Castlecliffian stage, as defined by Allan (1933), is the section from Landguard Bluff to Ototoka Creek, west of Wangauui. This includes the coast section at Castleclift. Fleming (1947) notes that beds higher than any exposed in the coastal section outcrop on the south-east bank of the Wanganui River (the Putiki and Landguard Bluff sections).
The beds are all of marine, shallow-water origin, mainly sands, silts, and shell beds (little consolidated), with intercalations of sands containing rhyolitic tuff and pumice evidently brought by the Wanganui River from the volcanic central district of the North Island. The total thickness at Wanganui is only a few hundred feet, with little conglomerate (none in the coast section). The section exposed along the Rangitikei River however, is several thousand feet thick, and conglomerate layers are frequent in it (Te Punga, 1952a). In both these sections molluscan fossils are abundant, and subdivision info numerous zones is possible.
Fleming divides the Castlecliff formations at Wanganui into Lower and Upper divisions at a previously known stratigraphical break exposed in the coast section between Castlecliff and Kaiwi. At the coast, the Lower division contains rhyolite pumice at a number of horizons, but in the Upper it becomes scarce Inland, the Lower division is largely pumiceous, and the Upper is “dominated by” heavy greywacke and andesite conglomerates.
In the coast section there are frequent minor breaks—wave-cut, scoured, and bored surfaces being covered by beach sands and then by fine sediments containing irregularly distributed lenticular beds of shells.
There has been some deposition with initial dips, but the beds are tilted away from their original attitude. The older the beds the steeper, as a rule, is their dip; from which intermittent and cumulative tilting during accumulation is inferred. This has led to emergence of newly deposited beds, and landward these have suffered erosion while deposition has continued seaward, as is shown by the frequent presence of derived fossils, which are found in beds 50 to 100 feet higher in the sequence than those from which the shells have been washed. “When the axis of tilting lay seaward, negative movement of the strandline
allowed wave attack …; when it lay inland, positive movement allowed accumulation of sediment at depth below the profile of equilibrium” (Fleming, 1947). The tilting thus indicated was geosynclinal on the margins of the “Palmerston-Wanganui basin” (so called by Ongley, in 1945, in a report on water resources). Exploration carried out by the Superior Oil Company indicates accumulation of 3,000 feet of sediment in part of this basin; while greater thickness in the Rangitikei River section (Te Punga, 1952a) shows that it reaches geosynclinal dimensions there (over 3,000 feet of Castlecliffian beds alone having been measured).
In the coast section there is, though perhaps only locally, unconformable contact at the base of the Castlecliffian, which rests on a channelled surface of Nukumaruan; and, above, the bevelled edges of Castlecliffian beds are covered unconformably by beach deposits of the generally marginal Quaternary Hawera Series. In the Rangitikei district, on the other hand, it is very probable that unchanged shallow-water marine conditions of sedimentation continued through late Pleistocene into “Recent” time (Te Punga, 1953; 1954).
In the coastal district from Wanganui to Taranaki, which includes the type locality (at Hawera) of the series, the formations upon which the Hawera Series is based are present covering two broad marine terraces that have successively emerged as coastal plains, one being now 300 to 500 and the other 50 to 100 feet above sea-level. Besides deltaic and dune sands these contain beds with marine molluscan fossils (Fleming, 1953). They unconformably bevel strata of the Wanganui Series.
The criterion of unconformity above the local development of the Notocenozoic is of little value, however, for correlation of the many formations throughout New Zealand that are tentatively attributed to the Hawera Series. If it is correct that t le upper part of the Rangitikei section includes beds of the same age as or younger than the Hawera formations that rest on eroded surfaces bevelling beds of the Wanganui Series north of Wanganui, these lying conformably above beds that are strictly Castlecliffian, then it is impossible to exclude the “Hawera Series” from the Notocenozoic. Nor, indeed, can it be said that the Notocenozoie era hi s yet come to an end.
Allan, R. S. 1933 On the system mid stage names applied to subdivisions of the Tertiary strata in New Zealand. Trans. N.Z. Inst., 63: 81–108.
— 1938. In R. Speight Mount Somers District. N. Z. N.Z. Geol. Mem., 3.
Bartrum, J. A., 1934. The pillow lavas and associated locks of North Cape area, N.Z. N. Z. Jour. Sci. Tech., 16: 158–9.
Bartrum, J. A. and Turner. F. J. 1928 Pillow lavas. peridotites, and associated rocks of northernmost New Zealand. Trans. N.Z. Inst. 59: 98–138.
Battey. M. H., 1952. The geology of Rangiowiua Peninsula, Doubtless Bay. North Auckland. Rec. Auckland Inst. Mus., 4 (1) 35–39.
Cotton, C. A., 1913. The physography of the Middle Clarence Valley New Zealand Geogr. Jour., 42: 225–46.
Cotton, C. A., 1916. Block mountains and a fossil denudation plain in northern Nelson. Trans. N.Z. Inst., 48: 59–75.
" 1917. Block mountains in New Zealand. Am. Jour. Sci., 44: 249–93 (footnote p. 250).
Cotton, C. A., 1945. Earth Beneath. Christchurch: Whitcombe and Tombs.
" 1951. Post-Hokonui orogeny, erosion, and planation. N. Z. Jour. Sci Tech., B33: 173–8
" 1954 Notocenozoic: the New Zealand Cretaceo-Tertiary. N.Z. Science Review. 12:105–112.
Coper, R. A., 1953. Upper Mesozoic and Cainozoic spores and pollen grains from New Zealand N.Z. Geol. Surv. Pal. Bull., 22.
Finlay, H. J., 1939. New Zealand Foraminifera: key species in stratigraphy, No. 1. Trans. Roil. Soc. N.Z., 68: 504–43.
" 1946. The microfaunas of the Oxford Chalk and Eyre, Beds. Trans. Roty. Soc. N.Z., 76: 237–45.
" 1947. The foraminiferal evidence for trans-Tasman correlation. Trans. Roy Soc N.Z., 76, 327–52.
" 1948. Addendum to E. O. Macpherson, The Upper Senonian transgression in New-Zealand, N.Z. Jour. Sci. Tech., B29: 293–6.
Finlay. H. J., and Marwick, J., 1937. Wangaloa faunas. N.Z. Geol. Surv. Pal. Bull., 15.
" 1940. The divisions of the Upper Cretaceous and Tertiary in New Zealand. Trans. Roy. Soc. N.Z., 70: 77–135.
" 1947. New divisions of the Upper Cretaceous and Tertiary N.Z Jour. Sci Tech., B28: 228–36.
Fleming, C. A., 1944. Molluscan evidence of Pliocene climatic change in New Zealand. Trans. Roy. Soc. N.Z., 74: 207–20.
" 1947 Standard sections and subdivisions of the Castlecliffian and Nukumniuan stages. Trans. Roy. Soc. N.Z., 76: 300–26.
" 1949 The geological history of New Zealand. Tuatara, 2: 72–90.
" 1953. The geology of the Wanganui Subdivision. N.Z. Geol. Surv Bull., 52.
Gage. M, 1945 Tertiary and Quaternary geology of Ross, Westland, Trans. Roy. Soc. N. Z. 75: 138–159.
" 1949. Late Cretaceous and Tertiary geosynclines in Westland. N. Z.Trans. Roy. Soc. N.Z., 77: 325–37.
" 1952. The Greymouth Coalfield. N.Z. Geol. Surv. Bull., 45.
Geological Survey, N.Z., 1948. Outline of the geology of New Zealand; to accompany the 16 mile to 1 inch Geological Map. 47 pp.
Grange, L. I., 1927. Geology of the Tongaporutu-Ohura Subdivision. Taranaki. N.Z. Geol. Surv. Bull., 31.
Hector, J., 1886. Outline of New Zealand Geology, Wellington.
Henderson, J., 1911. On the genesis of the surface forms and present drainage systems of West Nelson. Trans. N.Z. Inst., 43: 306–15.
" 1929. Late Cretaceous and Tertiary rocks of New Zealand. Trans. N. Z. Inst., 60: 271–99.
Hutton, F. W., 1875. Geology of Otago, Dunedin.
" 1885. Sketch of the geology of New Zealand. Quart. Jour. Geol. Soc., 41: 191–220.
Lillie., A. R., 1951. Notes on the geological structure of New Zealand. Trans. Roy. Soc. N.Z. 79: 218–59.
" 1953. Geology of the Dannevirke Subdivision. N.Z. Geol Surv. Bull., 46
Mckay, A., 1877. Report on Kakoura Peninsula and Amuri Bluff. Rep. Geol. Explor dur. 1874–6, 172–84.
Macpherson, E. O., 1946. An outline of Late Cretaceous and Tertiary diastrophism in New Zealand. N.Z. Geol. Mem., 6.
" 1948. The Upper Senonian transgression in New Zealand. N.Z. Jour. Sci. Tech., B29: 280–92.
Marshall, P., 1911. (With R. Speight and C. A Cotton.) The younger rock series of New Zealand. Trans. N.Z. Inst., 43: 378–407.
" 1912a. The younger rock series of New Zealand. Geol. Mag., (5) 9: 314–20.
" 1912b. Geology of New Zealand. Wellington: Govt. Printer.
" 1912c. New Zealand. Handbuch der regionalen Geologie, 7 (1), Heidelberg- Carl Winter.
" 1916a. The younger limestones of New Zealand. Trans. N.Z. Inst., 48: 87–99.
Marshall, P., 1916b. Relations between Cretaceous and Tertiary rocks. Trans. N.Z. Inst., 48: 100–19.
" 1917a. The Wangaloa Beds. Trans: N. Z. Inst., 49: 450–60.
— 1917b. Geology of the central Kaipara.Trans. N.Z. Inst., 49: 433–50.
— 1926. The Upper Cretaceous ammonites of New Zealand. Trans. N.Z. Inst., .56: 129–210.
Marshall, P., and Murdoch, R., 1920. Tertiary rocks near Wanganui. Trans. N.Z. Inst., 52: 115–28.
— 1921. Tertiary rocks near Hawera. Trans. N.Z. Inst., 53: 86–96.
Marwick, J., 1926. Molluscan fauna of the Waiarekan stage of the Oamarn Series. Trans. N.Z. Inst., 66: 307–16.
— 1934. The sequence of molluscan life in New Zealand. Rep. V. Pacific Sci. Cong., 947–60.
Mason, B., 1941. The geology of Mount Grey district, North Canterbury. Trans. Roy. Soc. N.Z., 71: 103–27.
Morgan, P. G., 1921. Review of results: classification of sedimentary formations. In H Suter, Lists of New Zealand Tertiary Mollusca, N.Z. Geol. Sure. Pal. Bull., 8: 98–104
— 1924. In T. H. Withers, The Fossil Cirripedes of New Zealand. N.Z. Geol. Surv. Pal. Bull., 10: 43.
— 1926. The definition, classification, and nomenclature of the Quaternary periods. N.Z. Jour. Sci. Tech., 8: 273–82.
Ongley, M.,Ongley, M., 1924. Cretaceous and Tertiary formations of New Zealand. N.Z. Jour. Sci. Tech., 7: 107–17, 171–80.
— 1939. Kaitangata-Green Island N. Z. Geol. Surv. Bull., 38.
Park, J., 1910. Geology of New Zealand. Christchurch: Whitcombe and Tombs.
— 1918. Oamaru District. N.Z. Geol. Surv. Bull., 20.
— 1921. Southland. N.Z. Geol. Surv. Bull., 23.
Speight, R., and Wild, L. J., 1918. The stratigraphical relationship of the Weka Pass Stone and Amuri Limestone. Trans. N. Z. Inst., 50: 65–93.
Suggate, R. P., 1950. Quartzose Coal Measures of West Nelson and North Westland. N.Z. Jour. Sci. Tech., B31 (4) : 1–14.
Suggate, R. P. and Couper, R. A., 1952. The stratigraphical relations and plant microfossils of New Zealand coal measures. N.Z. Jour. Sci. Tech., B34: 106–17.
Te Punga, M. T., 1952a. The geology of Rangitikei Valley. N.Z. Geol. Surv Mem, 8
— 1952b. Coloured fossils from New Zealand. N. Z. Jour. Sci. Tech., B39: 154–9.
— 1953. A late Pleistocene land bridge across Cook Strait. N.Z. Join. Sci. Tech., B35: 161–92.
— 1954. Fossiliferous late-Pleistocene beds in a well at Awahuri. near Palmerston North. N.Z. Jour. Sci. Tech., B36: 82–92.
Thomson, J. A, 1916. On stage names applicable to the divisions of the Tertiary in New Zealand. Trans. N. Z. Inst., 48: 28–40.
— 1917. Diastrophism and other considerations in classification and correlation, and the existence of minor diastrophic districts in the Notocene. Trans. N. Z. Inst, 49: 397–413.
— 1919. Geology of the Middle Clarence and Trans. valleys. Trans. Z.Z. Inst., 51: 289–349.
— 1920. The Notocene geology of the Middle Waipara and Weka Pass. Trans. N.Z. Inst., 52: 322–415.
Trechmann, C. T., 1917. Cretaceous Mollusca from New Zealand. Geol. Mag., (6) 4 294–305, 337–42.
Uttley, G. H., 1920. Tertiary geology of the area between Otiake River and Duntroon. Trans. N.Z. Inst., 52: 137–53.
Wellman, H. W., 1948. Geology of the Pike River coalfield, North Westland N. Z. Jour Sci. Tech., B30: 84–95.
— 1950. Ohika Beds and the post-Hokonui Orogeny. N.Z. Jour. Sci. Tech., B32: (3) 11–38.
— 1953. The geology of Geraldine Subdivision. N.Z. Geol. Surv. Bull., 50.
Wilckens, O., 1922. The Upper Cretaceous gastropods of New Zealand. N.Z. Geol. Surv. Pal. Bull., 9.
Woods, H., 1917. The Cretaceous faunas of the north-eastern part of the South Island of New Zealand. N.Z. Geol. Surv. Pal Bull., 4.