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Volume 48, 1915
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Art. IX—Relations between Cretaceous and Tertiary Rocks.

[Read before the Otago Institute, 7th December, 1915]

  • I.

    Classifications of the younger rock-series of New Zealand.

  • (a.)

    General.

  • (b.)

    Hector's work.

  • (c.)

    Hutton's classification.

  • (d.)

    Park's classification.

  • (e.)

    Morgan's classification.

  • (f.)

    Marshall, Speight, and Cotton.

  • II.

    Relationship between Cretaceous and Tertiary rocks.

  • (a.)

    Western and southern Europe.

  • (b.)

    Pacific region.

  • (1.)

    California.

  • (2.)

    Chile.

  • (3.)

    Patagonia.

  • (4.)

    Magellan region.

  • (5.)

    Antarctica.

  • (6.)

    New Zealand.

  • (v.)

    Wangaloa.

  • (w.)

    Hampden.

  • (x.)

    Brighton.

  • (y.)

    Selwyn Rapids.

  • III.

    Conclusions.

I. Classifications Of The Younger Rock-Series Of New Zealand.

(a) General.

It is well known that much discussion has taken place in New Zealand in regard to the relation between the Cretaceous and the Tertiary rocks from the stratigraphical and palaeontological points of view. Much difference of opinion has been expressed, and, while some of the views which have been advanced have now been allowed to lapse for want of support, it would be foolish to suggest that any unanimity of opinion exists in regard to this vexed question.

The matter is not one of mere academic importance, but is actually the geological question that carries in its train the most important conclusions in regard to the extent and occurrence of the productive coal-measures in all parts of the country. So far as the coal-measures themselves are concerned, the difference of opinion amounts to this: Some geologists maintain that there are at least two coal-bearing horizons, while others think that there is only one horizon of any importance at any locality, and that this horizon is always at the base of that development of the younger rocks which is found in the locality.

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The following table summarizes the classifications of the younger rock-series which have been proposed by various geologists:—

Hector, 1886. Hutton, 1885. Park. Morgan. Marshall.
Pliocene Wanganui, lignite at base Wanganui Wanganui.
Miocene {Upper Lower} Pareora, coal at base Oamaru, coal at base Oamaru, coal at base The whole series classed as Oamaru series. Coal at the base of that development of the system present in any locality.
Oligocene Oamaru, coal at base
Eocene—Upper Waimangaroa, coal at base Waimangaroa, coal at base
Cretaceo-tertiary, coal at base
Cretaceous, Lower Greensand, coal Waipara, coal at base Amuri, coal at at base

The rather surprising variety of opinion shown by this table is partly accounted for by the isolated position of many of the coal-basins, and by the somewhat confusing nature of the palaeontological collections which have been made in some of the coal-bearing localities. From the purely stratigraphical standpoint the perfect conformity of the members of the whole series does not give room for much difference of opinion—in those places, at least, where the complete series is developed. This matter has, however, been dealt with at some length in a previous paper,* in which it was shown that at the Waipara and at Amuri Bluff there occurs a complete conformable series of sediments. The lowest beds of this sequence contain distinct Cretaceous fossils, whilst the nature of the abundant fossils in the highest member makes it necessary to regard this as of Upper Miocene age.

More recently sections have been examined in the Trelissick basin by Speight which demonstrate the same fact more clearly than ever.

In the paper just referred to emphasis was laid on the fact that the series in all those three districts in which it is well developed shows in its lower members a sequence of sediments that clearly indicates progressive deepening of the water in which the sediments were deposited. In the upper members of the series the reverse is found, for these strata show that a gradual shallowing of the water was in progress.

The order of superposition of the sediments throughout the country is so similar in its general bearings that it is thought possible, and advantageous, and sufficiently exact, to state the succession of the strata in the following order:—

  • (8.)

    Gravels.

  • (7.)

    Sands.

  • (6.)

    Mudstones.

  • (5.)

    Greensands.

  • (4.)

    Limestone.

  • (3.)

    Greensands.

  • (2.)

    Sands.

  • (1.)

    Gravels (often with coal).

In those localities, such as Waipara, where the series is complete, fossils which indicate a Cretaceous age are found as high in the formation as the

[Footnote] * Marshall, Speight, and Cotton, “The Younger Rock-series of New Zealand.” Trans. N Z. Inst., vol. 43, 1911, p. 378

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lower part of the greensands, which are often of a concretionary nature. In other localities a Tertiary fauna has been found in the upper part of the greensands, though it usually happens that these strata are destitute of fossils.

The order of succession of the strata which is given here is, of course, subject to no small variation. In particular, the greensands, which it is well known require particular and special conditions of temperature and currents for their formation, are not developed in some localities. In others it may happen that thick beds of mudstone occur between the sands and the limestone, and these are sometimes oil-bearing. In all localities as far as known at present there is a considerable thickness of unfossiliferous strata between the Cretaceous horizon and the lowest Tertiary horizon in which fossils occur.

The highly diverse classifications of the younger rocks of New Zealand which have already been quoted clearly show that there is considerable difficulty in harmonizing those details of stratigraphical and palaeontological facts that have been discovered. All of the classifications appear to be ultimately due to the recognition of the fact that the coals of New Zealand are clearly of different age in the various localities in which they occur, for they are associated with different molluscan faunas. It is perhaps as well to state here some of the merits and demerits of each of the classifications.

(b) Hector's Work

The classification of Hector had its first appearance in the New Zealand Geological Reports, 1876–77, pp. iii-iv, but its first comprehensive description was in 1886, in the “Outline of the Geology of New Zealand,” prepared for the Indian and Colonial Exhibition, held that year in London. On page 55 it is stated, “These strata constitute the Cretaceo-tertiary formation, being stratigraphically associated, and containing many fossils in common throughout; while at the same time, though none are existing species, many present a strong Tertiary facies from both the highest and lowest part of the formation, but even in the upper part a few are decidedly Secondary forms.”

His position is, however, more clearly stated in the New Zealand Geological Reports for 1890–91, p. 1. He there states, “Successive efforts to prove the age of the beds by the fossils were disappointing, and led to attempts to correlate the beds with their supposed equivalents by means of stratigraphy and the sequence of the prominent lithological characters of the various divisions of the strata constituting the Waipara formation. Over wide areas a correspondence of the sequence in regular and varying order was traced, and at very many places in both Islands these beds proving richly fossiliferous were largely collected from. But the palaeontological evidence over the whole of South Canterbury and Otago and on the west coast of the South Island was apparently wholly in favour of the Tertiary age of these beds, while in the north-east, or Marlborough, district of the South Island, and along the east coast of the North Island from Cape Palliser to Cape Kidnappers, and from Poverty Bay to East Cape, the evidence obtained from beds stratigraphically and lithologically the same demonstrated their Cretaceous age.”

Other sentences on page li show clearly that Hector thought that no unconformity separated his Cretaceo-tertiary from his Lower Greensand formation. This extract clearly shows that an identical stratigraphical

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sequence was found which contained in the basal beds fossils of different ages in various localities; but at the same time the faunas were so related in all the localities that Hector considered it advisable to place them in the same series.

This hardly seems to merit the remarks of Wilckens,* “Hector's whole Cretaceo-tertiary formation, which contains pell-mell a motley collection of Cretaceous and Tertiary fossils alongside of Jurassic and Recent plant-remains, is at least doubtful.”

Hector's work clearly shows the essential nature of the problem, which is admitted by all observers: (1.) That the younger series of rocks rests unconformably on an older series, whether Jurassic or Triassic sediments or schists, and on these older rocks the younger series was deposited after a prolonged period of erosion. (2.) The basal members of this younger series of rocks are of Cretaceous age at Amuri Bluff, Waipara, Trelissick basin, East Wellington, Hawke's Bay, North Auckland, and elsewhere. This is amply proved by the fossils being in some cases reptilian types—Plesiosaurus, Mauisaurus, &c.; though in others merely Mollusca, such as Trigonia, Inoceramus, Conchothyra, Ammonites, and Belemnites. (3.) In other localities the basal fauna is as clearly Tertiary, which is generally the case in South Canterbury and Otago. (4.) In those places where the basal beds are of Cretaceous age they pass up into strata that are distinctly Tertiary; but, unfortunately, in any particular section, with a considerable thickness of intervening beds which contain no fossil remains.

Actually the only point at issue is whether this change of fauna is associated with a stratigraphical break or whether there is a complete stratigraphical conformity. Opinion based upon geological knowledge and experience obtained in other countries or from reading would at once decide on the former of these alternatives. It is only work in the field in this country that has caused various geologists to adopt the latter alternative, and it may at once be said that this attitude is adopted not only after a close inspection of the stratigraphical sequence, but in accordance with the lithological character of the beds, which demands a gradually increasing depth of water as one rises through the series from the Cretaceous to the Tertiary strata.

(c) Hutton's Classification.

Hutton's position is perfectly clear, and it is certainly one that must strongly commend itself to those geologists who have not visited the country, or who have not become personally acquainted with the problem in the field. He maintained that the Cretaceous beds are separated from those of Tertiary age by a distinct stratigraphical break. In the typical districts of North Canterbury, at the Weka Pass, and at the Waipara this break is placed between a Globigerina limestone (Amuri limestone) and a glauconitic arenaceous limestone (Weka Pass stone). The former is in these localities the highest member of the unfossiliferous beds which separate the beds containing Cretaceous fossils from those with a Tertiary fauna.

[Footnote] * O Wilckens, “Revision der Fauna der Quiriquina Schichten,” Neues Jahrb. fur Min, &c., Beil.-Band xviii, p. 279.

[Footnote] † F. W. Hutton, “Geological Position of the Weka Pass Stone,” Quart. Journ. Geol Soc., 1885, p. 266; also, “Sketch of the Geology of New Zealand,” Quart. Journ. Geol Soc, 1885, p. 207.

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In regard to this matter it can only be stated that the great majority of geologists who have seen this junction regard it as a conformable one. These include Hector, McKay, Skeats, Marshall, Speight, and Cotton. So far as published statements are concerned, Park is the only observer who has supported Hutton. This support, which is in total opposition to all previous statements of this author, has been accorded within the last few years only. The change of opinion is due to the recent discovery of Tertiary fossils in the Weka Pass stone, which formation Park had for many years placed in the Cretaceous System, and had separated by an unconformity from the well-known Tertiary beds above. Recent examination of the two limestones under the microscope has satisfied me as to their essential identity. As the junction is approached closely the Amuri limestone loses its most characteristic pure Globigerina nature and acquires a notable amount of minute quartz grains, as well as some glauconite and particles of a hydrous brown micaceous mineral. These are the characteristic minerals of the glauconitic Weka Pass stone, which rests on it. This surely proves that there is no stratigraphic break.

Hutton claimed that palaeontological evidence supported his position; but this statement must be accepted with caution, as the Amuri limestone is almost wholly unfossiliferous, and those fossils which have been collected in it, such as Pecten zitteli Hutton, are certainly Tertiary forms. In addition, the Amuri limestone, both at Waipara and at Amuri Bluff, rests on other beds of considerable thickness which also contain no fossils.

(d.) Park's Classification

Park's latest position appears to be identical with that of Hutton so far as the relationship of the Cretaceous to the Tertiary beds of North Canterbury is concerned. This position, however, has not yet been fully stated, while there are long statements by this author showing—(1) The conformable relations of the whole series; (2) the conformity between the Amuri limestone and the Weka Pass stone * Until full reasons are given for this change of front it must be assumed that there is no further information beyond that given by Hutton.

(e.) Morgan's Classification.

Morgan's position is at present based upon coal-occurrences in Westland. He states, that there is in that district a stratigraphic break between the so-called Eocene and the Miocene; but the evidence of this is of a lithological nature mainly. Insistence in particular is laid upon the occurrence of pebbles of coal derived from the lower members of the series embedded in the upper members. This, however, is not an uncommon occurrence in coal-measures. Thus in Arber's book on “The Natural History of Coal,” p. 131, instances are quoted of the occurrence of pebbles of coal in the sandstones of the coal-measures of the South Wales coalfield and that of Bristol, as well as in the Midlands. Further instances are quoted from the coalfields of France. Recently Prouty has recorded the occurrence of large and small pebbles of coal in the detrital beds of the coalfields of Alabama

[Footnote] * J. Park, N.Z. Geol. Rep., 1883, p. 33, Trans. N.Z. Inst., vol. 37, 1905, p 542; “Geology of New Zealand,” 1910, p. 88; Geol. Mag, dec v, vol. viii, 1911, p 541.

[Footnote] † P. G. Morgan, Trans. N.Z. Inst, vol 46, 1914, p. 271

[Footnote] ‡ W. F. Prouty, Jour. of Geol., vol 20, 1912, p. 769.

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In New Zealand, pebbles of coal occur in the grit near the Selwyn Rapids, in Canterbury. These beds are stratigraphically lower than the marine fossiliferous beds of Cretaceous age, yet there is no doubt that their coal is derived from the neighbouring coal-seams of Cretaceous age. This occurrence of detrital coal derived from beds of the same series may therefore be regarded as by no means abnormal.

Further attention is called by Morgan to a discordance between strike and dip, and to possibly unconformable contacts; but it is stated by him that such appearances may be due to faulting, which has been pronounced in that district. An overlap of the Miocene over the Eocene is also referred to by him as an evidence of a stratigraphical break, though this does not seem to imply such a structure when it is realized that during the deposition of the series of younger rocks there is throughout the country strong evidence of rapid depression. No palaeontological evidence has been brought forward by Morgan. Bartrum, however, says of this district, “It is a significant fact that wherever both are developed the Miocene series has been found to rest with perfect conformity on the Eocene.”*

Morgan has recently given a brief statement of the palaeontology of his Eocene. Among the Foraminfera is Amphistegina or a closely allied genus. This appears to suggest the Miocene, or perhaps Oligocene, rather than the Eocene age. Ten species of Mollusca have been identified, and nine of these species are well known to occur elsewhere in New Zealand in beds that have always been regarded as of Miocene age. The tenth species is undescribed. Two species—i.e., 20 per cent. of this small collection—are Recent species. It is difficult to see any reason for supposing that such a fauna could be characteristic of the Eocene as compared with the New Zealand Miocene. Morgan has also reviewed the opinions held in regard to the stratigraphical relation between the Amuri limestone and Weka Pass stone at the Weka Pass. He considers that there is some discordance, and, in opposition to all other observers, suggests that this discordance may mark the plane of separation between the Eocene and Miocene. He offers no palaeontological evidence.

(f.) Marshall, Speight, and Cotton.

The position taken by Marshall, Speight, and Cotton is this: It was recognized that the base of the younger series of rocks is of Cretaceous age in several localities, notably at the Weka Pass, at Amuri Bluff, and at Waipara; and it was maintained that there was a clearly conformable stratigraphical sequence from beds with Cretaceous fossils, through a thick series of unfossiliferous strata, to beds apparently of Miocene age. Since this paper was published Speight has discovered a section of a similar nature in the Trelissick basin where the thickness of the unfossiliferous strata is less, but the conformity of the rock-series is equally evident.

It is a matter of common agreement among all those authors that have been quoted that there are many localities where the fossiliferous Miocene rocks, often with coal at the base, rest directly upon the basement of the older rock-series. This occurrence of Cretaceous rocks at the base in some places and of Miocene rocks at others is the point which caused Hector to establish the Cretaceo-tertiary series, Hutton to insist upon a Cretaceous (Waipara) and an Oligocene (Oamaru) formation, and Park to describe a

[Footnote] * J. A. Bartrum, Trans. N.Z. Inst., vol. 46, 1914, p. 257.

[Footnote] † P. G, Morgan, Bull. N.Z. Geol. Surv. No. 17, 1915, pp. 80, 81.

[Footnote] ‡ P. G. Morgan, Ninth Ann. Rep. Geol. Surv. N.Z., 1915, p. 92.

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Cretaceous (Amuri) and a Miocene (Oamaru) division. A similar difference in the age of the basement rocks in Westland caused Morgan to separate the Eocene (Waimangaroa) and Oamaru (Miocene) formations in Westland.

It was stated by Marshall, Speight, and Cotton, that this difference in the age of the basement beds in various sections was the necessary overlap of the younger over the older members of a conformable series deposited during a prolonged period of depression during which the downward movement was more rapid than the building-up by the accumulation of sediment. This rapid depression caused the series to be deposited in the following order of succession:—

  • (4.)

    Limestones.

  • (3.)

    Greensands.

  • (2.)

    Sands.

  • (1.)

    Conglomerates.

It was held that the stratigraphical and the lithological evidence were perfectly definite, but it was admitted that at that time there was no palaeontological evidence in support of the position taken up by the authors. So far as palaeontological work had gone, it appeared that the Cretaceous fossils at the base of the series were quite distinct from the Miocene fossils in the higher members of the series, and, so far as known, could not even be regarded as an ancestral fauna of the latter.

At that time, however, the Cretaceous fauna had never been described; but that great gap in our knowledge has now been partly filled, for Mr H. Woods has recently described the collections of lamellibranchs and cephalopods from Amuri Bluff and other typical Cretaceous localities. His work has not yet been published, but it is understood that he classes the Amuri Bluff, Waipara, and Selwyn Rapids beds in the Senonian.*

The knowledge of the Tertiary fauna was also in an unsatisfactory state, because the types had not been figured, and for the most part they were not available for study, and the collections had not been closely defined as to locality and horizon. Specific identification was therefore inexact, and it was impossible to find in many places in what portion of a series the fossils had been collected—whether from sands, greensands, limestones, or marls.

Within the last few years extensive collections have been made in definite horizons in various districts—Clarke in the Waitemata beds of Auckland, Speight in the lower Waipara Gorge, Gudex at the Blue Cliffs in South Canterbury, Marshall and Uttley at many localities near Oamaru. These collections have shown that the division of these Tertiary rocks into Upper Miocene, Lower Miocene, Eocene, and Cretaceo-tertiary by Hector, and into Oligocene and Miocene by Hutton, and into various divisions of the Miocene by Park need considerable revision.

Hutton had previously drawn attention to the close relationship between his Miocene (Pareora) and Oligocene (Oamaru) formations by stating that, of 268 species of Mollusca found in the Tertiary series, thirty-three species were restricted to the Oamaru, and 184 species to the Pareora, while fifty-one species (a percentage of 19) were common to the two formations; or, of the eighty-four species of the Oamaru, as much as 60 per cent occur in the Pareora. Marshall, in fairly complete collections near Oamaru, finds in the greensands of Wharekuri, below the limestone, fourteen Recent

[Footnote] * N Z Parl. Paper C-2, Geol Surv, Ninth Ann Rep. (n s.), 1915, p 76

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species in a collection of sixty, a percentage of 23–3; in the horizon of the limestones at Otiake, fifteen Recent species in a collection of sixty-one, a percentage of 24; in the upper greensands directly above the limestone, forty-seven Recent species in a collection of 155, a percentage of 33; in the next horizon—that of the marls at Awamoa—twenty-one Recent species in a collection of sixty-four, a percentage of 35. Of these strata, it appears that the last two would have been placed in Hutton's Pareora (Miocene) system, and the two former in the Oamaru (Oligocene) system; yet some 75 per cent. of the species of the limestone horizon occur also in the upper greensands. So far as it goes, this collection of fossils from Oamaru shows a constant increase in the numbers of Recent species. No allowance had been made for the increase in the depth of water in which the sediments were deposited, nor for our lack of knowledge of the fauna of the deeper water off the New Zealand coasts. In this case, however, it is probable that the differences in the depth of water was not very great.

It is noticeable that Murex and Arca have not been found in the lower beds, while Exilia and Niso have been found in the lower only. This, of course, may be due to incomplete collecting, and the dominant fact emerges that the species are so similar throughout that the beds obviously all belong to one series; and the palaeontological results confirm the statement of the order of succession of the strata that was based on stratigraphical considerations. Even in the lowest of the strata, however, the fauna is distinctly of a middle Tertiary type when judged by European equivalents or by the percentage of Recent species. As previously pointed out, this latter criterion may be misleading, for it is quite possible that the rate of faunal change in New Zealand, owing to its complete isolation, may be extremely slow. So far as the results that have been obtained at Oamaru up to the present time are concerned, it may be said that there is no indication of a transition from Cretaceous to Tertiary types. Collections have not yet been made from the Black Point beds, where McKay collected some Cretaceous fossils, though Park subsequently collected Tertiary types only.

II. Relations between Cretaceous and Tertiary Rocks in other Countries.

It appears to be generally thought that there is a great stratigraphical break between the Cretaceous and the Tertiary strata throughout the world. Wilckens, in his work on the younger sediments of Patagonia, has expressed this opinion in its most extreme form. He says, “The division between the Cretaceous and the Tertiary is one of the sharpest known in the whole earth's record. Here occurs a break in our knowledge of our planet which has up to the present been maintained complete…. We know of no marine sediments which correspond in age to the interval between the two periods.”* In such sweeping statements it appears that the palaeontological side of our knowledge is given great emphasis at the expense of our stratigraphical information.

In regard to this point, it may be of value to quote the statements made in standard works, since the detailed researches in which the actual original observations of geologists have been recorded are not available. Thus Chamberlin and Salisbury, in discussing the age of some American strata, state, “If the presence of saurian fossils demonstrates the Cretaceous

[Footnote] * O Wilckens, “Die Meeresablagerungen der Kreide- und Tertiarformation in Patagonien,” Neues Jahrb. Min., &c . Beil -Band xxi, 1905, p 147.

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age of the beds containing them, the Arapahoe and Denver beds are Cretaceous, but every other consideration seems to point rather to their inclusion to the early Tertiary…. The invertebrate fauna of the Denver beds is little known, and the identified species are common to both the Cretaceous and Eocene.”* On page 216, in connection with the relation between these formations in Europe, the authors say, “The break between the Cretaceous and the Eocene was long regarded as one of the, great breaks in the geological record, but the hiatus is partially and imperfectly bridged by the estuarine, lacustrine, and other deposits of the early Eocene. It is not to be lost sight of that the one period merged insensibly into the next, even though the strata which recorded the transition are not to be found in every region. In southern Europe the separation of Cretaceous from Eocene is much less sharp, showing that the notable geographic changes of the western region did not affect the southern and south-eastern parts of the continent, or, at least, not to the same extent.”

(a.) Western and Southern Europe

The most detailed treatise that is available in regard to the stratigraphy of the geological formations of Europe is the “Traité de Géologie” by de Lapparent. In discussing the Danian, on page 1469 of vol. iii (5th ed.), he says, “Divers auteurs, notamment M. de Groussouvre, se sont fondés sur l'extinctions des ammonites pour faire du danien le premier terme du groupe tertiaire. Ce qui nous détermine à le laisser dans la série néocrétacée, c'est le phénomène de régression qui a marqué la période danienne, et qui semble mieux convenir à la fin d'une époque qu'a l'inauguration d'une ère nouvelle.” Here at least it is clear that the demands of stratigraphy are given a place of prior importance to the requirements of palaeontology. Later, where the same author speaks of the Montian formation, he says, “Plusieurs auteurs font du calcaire du Mons le terme inférieur du terrain tertiaire. Pour le maintenir dans la série néocrétacée, nous nous fondons, non seulement sur l'affinité paléontologique de cette assise avec le calcaire pisolithique de Paris, mais aussi sur ce fait que son dépôt correspond à un maximum de régression, précédant la grande invasion marine du début des temps tertiaires” (pp. 1470–71). Here again great importance is attached to the stratigraphical aspect of the question as a criterion for deciding upon the dividing plane between the Cretaceous and the Eocene. On the following pages further statements are made showing that the passage from the Cretaceous to the Tertiary is to be found in a continuous series of conformable sediments in Istria, in the Peloponnesus, in the Deccan of India, and in Tunisia.

(b.) Pacific Region

It is, however, with the Pacific region that we are mostly concerned, and here it will be found that in many localities there is the greatest difficulty in deciding where the Cretaceous ends and where the Tertiary begins. There are at least five regions where marine fossiliferous beds show in the same series both Cretaceous and Tertiary strata. These regions are California, Chile, Patagonia, Seymour Island, and New Zealand. Since the descriptive and critical literature in regard to the geological features of these districts is scattered and not readily obtainable in this country, it is advisable to summarize the main points, as they have a great importance in connection with the geology of New Zealand.

[Footnote] * T C Chamberlin and R D Salisbury, “Geology,” vol [ unclear: ] , 1906, p 158

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(1.) California.

The localities are in the great valley of California, near Chico and Martinez. The fossils found there were first described by Conrad,* who regarded them as Tertiary, while Gabb thought them to be of Cretaceous age. Later on White gave a more detailed account of the stratigraphy. He says, “The strata which constitute the Tejon, Martinez, and Chico groups of Gabb form one unbroken series, which rests unconformably on all the rocks beneath it, and on which the Miocene rests conformably. The Tejon portion of the series represents the Eocene; the Chico portion the closing epoch of the Cretaceous. But there is an alternate mingling of types throughout the whole series, so that no horizon can be distinguished that will separate all the Cretaceous types on the one hand and all the Tertiary types on the other. In other words, there is an unbroken faunal and stratigraphic continuity from the Cretaceous to the Tertiary part of the series.”

The same author says elsewhere, “In the case of the Tejon Chico series unbroken marine conditions existed…. It is true that on the western border of the continent we find the marine Cretaceous merging into the marine Eocene.”§

Fairbanks remarks of this series, “The Chico-Tejon has a thickness of at least 20,000 ft. in several places. We have no knowledge at present of a stratigraphic break in the series.”

The latest worker on this series is Stanton, who states, “(1.) In all known sections which contain both Chico and Tejon [faunas] the strata are apparently conformable…. (5.) The Chico is characteristically Cretaceous, its so-called Tertiary types being persistent or modern types that have changed but little from the Cretaceous to the present day. (6) An examination of the species supposed to occur in both the Chico and Tejon reduces the number to not more than six, and with one exception these are all persistent types that cannot be classed as Mesozoic. The one exception is Ammonites jugalis. It is held that the Tejon fauna is essentially Eocene, and very distinct from the Chico, even though this ammonite should prove to belong to it. (7.) The time interval indicated by the decided change in faunas cannot now be estimated. In fact, there is little evidence that the later fauna is directly derived from the earlier except in a few species, and it is possible that all the changes took place by extinction and migration of species during the period in which the barren beds between the latest Chico and the earliest Tejon were laid down.”

In the Martinez group, which constituted the transition series between the Cretaceous and Eocene of Gabb, fifty-two species of Mollusca occur. Of these, Stanton admits four species as occurring certainly in both, and an additional six species as occurring doubtfully in both. Gabb had previously stated that sixteen species occurred generally in both the Chico and Tejon series. Stanton reduces this number to six. He places the division between the Chico and the Tejon in the middle of the Martinez. He gives no stratigraphical diagrams or maps. He further states (p. 1033), “Excepting the

[Footnote] * Am. Journ. Sci., 44, 1867, p. 376.

[Footnote] † “Palaeontology of California,” vol. 1, ii.

[Footnote] ‡ C. A. White, Bull. U.S. Geol. Surv. 15, 1885, p. 3.

[Footnote] § U.S. Geol. Surv. Bull. 82, 1891, pp. 200, 201.

[Footnote] ∥ Jour. of Geol, vol. 3, 1895, p. 433.

[Footnote] ¶ U S. Geol. Surv., 17th Annual Rep., 1896, p. 1035.

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meagre evidence of the occurrence of ammonites in the Tejon, it cannot be held that the fauna of any part of the Tejon contains important Mesozoic elements.”

Wilckens has discussed Stanton's work, and states that Stanton “Die vollige zeitliche Verschiedenheit der Chico und der Tejon Gruppe nach-gewiesen hat wird. Die Chico Gruppe ist obercretasich, die Tejon eocan.”* This statement appears to imply that there is a well-marked division between the beds, a conclusion that is certainly not supported by the quotations from Stanton that have been given above. One must, however, agree with Wilckens that definite lists of the Chico and Tejon species are urgently required. He appears to regard the Chico as the highest division of the Senonian, and with it he places the Nanaimo division of the Canadian Pacific. He also draws attention to the fact that a detailed description of the Chico is still wanting, and that it is not possible at present to find out from the literature what forms belong to the Chico and what forms are of Tejon age.

Finally, he says that, so far as the literature enables him to form an opinion, it appears that the highest member of the Cretaceous rests in places on the Lower Cretaceous, and in the east on the crystalline rocks at the foot of the Sierra Nevada. The fauna of these beds reveals their age as Upper Cretaceous by means of the Ammonites and Baculites, and still more by the typical occurrence of gastropods such as Pugnellus and Gyrodes; and it has a Pacific character. It is more closely related to the Indian and Quiriquina fauna than to that of other American localities. He draws more comparisons between the Chico, Nanaimo, and Quiriquina beds, and shows that the Nanaimo transgressed as did the Chico on the older crystalline rocks.

Even in the Gulf of Mexico region the plane of separation from the Cretaceous is not definitely decided. The latest suggestion is to include in the Cretaceous a stratum which contains a molluscan fauna without cephalopods, and which has, with one exception, only Tertiary genera.

(2.) Chile.

The work of d'Orbigny and of Darwin§ first gave us information of the occurrence of fossiliferous beds in this part of the world. One of the most important localities is the Island of Quiriquina, in the Bay of Concepcion. Of the fossils found here, Darwin remarks, “Although the generic character of the Quiriquina fossils naturally led M. d'Orbigny to conceive that they were of Tertiary origin, yet as we now find them associated with the Baculites vagina and an ammonite we must, in the opinion of M. d'Orbigny, if we are guided by the analogy of the Northern Hemisphere, rank them in the Cretaceous system.” On page 131 he further says, “From these [stratigraphical] facts, and from the generic resemblance of the fossils from the different localities, I cannot avoid the suspicion that they all belong to nearly the same epoch, which epoch, as we shall immediately see, must be a very ancient Tertiary one.” Included in this general statement were the beds of Navidad, 160 miles north of Concepcion and sixty miles south of Valparaiso.

[Footnote] * O Wilckens, “Revision der Fauna der Quiriquina, Schichten,” Neues Jahrb fur Min, &c., Beil.-Band xiii, 1904, p 281.

[Footnote] † Journ. of Geol., xxiii, 1915, p. 523.

[Footnote] ‡ “Voyage dans l'Amérique méridionale,” 1842, Parties in, iv.

[Footnote] § “Geological Observations in South America,” 1851, p 126.

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The first really detailed description of these beds and of those at Coquimbo, near Valparaiso, was written by Steinmann and Möricke,* who classed the former as Miocene and the latter as youngest Miocene or Pliocene.

The Tertiary beds of New Zealand are quoted as a parallel because of the occurrence of Natica solida Sow. and of Limopsis insolita Sow. in both countries, and of the closely related forms in New Zealand to Scalaria rugulosa Sow. and Crepidula gregaria Sow. which occur in the South American beds.

The comparison by Wilckens of the Quiriquina beds of South America with the New Zealand strata is, however, of greater importance. These Quiriquina beds were first fully described by Steinmann and Möricke, but later, with the aid of more abundant material, by Wilckens. The collections were obtained from two neighbouring localities on the mainland, as well as the Island of Quiriquina itself. The fauna from the three localities is practically identical, and is also of very similar age to that of Algarrobo, 210 miles farther north, near Valparaiso. Wilckens compares the gastropods of these beds with those of other Cretaceous strata in the Pacific region. Pugnellus uncatus, however, is not found at Quiriquina, which has the species Pugnellus tumidus Gabb. Eriptycha chilensis d'Orb. comes near to Cinulia obliqua Gabb, and Pyropsis hombriana d'Orb. is related to Pyropsis species from the Foxhill beds of Chico. Pugnellus is here stated to be very characteristic of the Senonian of the Pacific coast. It ranges from the Turonian to the Senonian. Emphasis is laid on the absence of knowledge of the Waipara fauna of New Zealand.

Wilckens continues with the statement that it is obvious that a sea united all those regions with a similar Upper Cretaceous fauna on the margin of the Pacific. This sea overflowed its coasts in later Senonian time, and laid down such deposits as those at Quiriquina. Finally he states that “The descendants of the Quiriquina fauna are found in the Patagonian Tertiary. An important problem lies in their relationship to the Eocene fauna of central Europe, as shown by the many similar species that occur in both.”

The Indian Cretaceous contains in the Ariyalur group a formation generally similar in its fauna to the Quiriquina. The gastropod genera Pugnellus, Gyrodes, Pyropsis, and Eriptycha are again represented. Kossmat classes with these Indian strata the Cretaceous beds in Natal, Madagascar, Assam, Borneo, Yesso, Vancouver, and Quiriquina.

(3.) Patagonia.

A highly important formation in respect of the relationship of the Upper Cretaceous of the Pacific region to the Tertiary is found in Patagonia. For much of our knowledge of this we are again indebted to Wilckens. He at once states that this horizon is distinctly higher than that of the Cretaceous of Columbia, Peru, and the Chilian and Argentine Cordillera. Though on the east side of the Cordillera, and resting on a great thickness of Older Cretaceous sediments, instead of crystalline rocks as at Quiriquina, it is still the case that the nearest affinities of the fauna are with the Quiriquina, though there is also a distinct resemblance to the Patagonian Miocene. In

[Footnote] * G. Steinmann and W. Moricke, “Die Tertiarbildungen des nordlichen Chili und ihre Fauna,” Neues Jahrb. fur Min, &c, Beil.-Band x, 1896, pp. 533–612.

[Footnote] † O. Wilckens, “Die Lamellibranchiaten, Gastropoden, &c, der oberen Kreide Sudpatagoniens,” Ber der. nat. Ges., Freiburg, Bd. xv, 1907.

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many respects the fauna is intermediate between that of the Quiriquina and that of the Patagonian Miocene, for it has many relationships to both. Nevertheless, he regards the Patagonian Cretaceous as the equivalent of the Quiriquina; the differences that are noticed between the faunas are regarded as due to the 1,000 miles of distance which separates the localities. The Patagonian formation is considered by Wilckens to be equivalent to the Navidad, of Miocene age, and the differences between these two series, though somewhat greater than those between the Quiriquina and the Patagonian Cretaceous, are still of the same order of magnitude.

At first sight, Wilckens says, the Patagonian Upper Cretaceous is apparently Tertiary, especially since, with the exception of Baculites, no cephalopods have been found. The bivalve and gastropod fauna, however, contains so many very characteristic Cretaceous genera that no doubt can be entertained that it is of Cretaceous age. Pugnellus and Cinulia are wholly absent from the Tertiary. Trigonia, Pyropsis, and Struthiolariopsis also indicate the Cretaceous. Then come also the very close relationships to the Quiriquina (previously described by him as Senonian). The Patagonian Cretaceous contains many elements of the Miocene, and the following eighteen genera are quoted as occurring in both: Schizaster, Nucula, Leda, Malletia, Cucullaea, Pecten, Mytilus, Amathusia, Corbula, Panopea, Martesia, Dentalium, Scalaria, Galerus, Natica, Turritella, Aporrhais, Bulla.

(4.) Magellan Region.

Here again the exact stratigraphical relations between the Patagonian formation (Miocene) and the Senonian beds has given rise to a large amount of discussion, and a great divergence of opinion has been expressed. The latest description of the fossils in this part of South America is by Steinmann and Wilckens.* This work, however, gives little stratigraphical information on the question, except that the statement is made that fossils indicating the Patagonian molasse (Miocene) were obtained from the deep part of a river-valley where the mapping indicates Cretaceous rocks.

A full discussion of the stratigraphical relations of the various members of the Patagonian region was written by Wilckens in 1905. He revises the opinions of those geologists who have given descriptive accounts of the stratigraphical relations of the strata. Ameghino speaks of the gradual transition from the Cretaceous to the Tertiary which is to be seen in Patagonia. Ihering speaks of a gradual passage from the Cretaceous fauna to that of the Patagonian formation (Miocene). Hauthal says, in opposition to the statements of Steinmann, that he has found no discordance between the Cretaceous and the Tertiary in south-west Patagonia.

Wilckens, after discussing the statements of these various geologists, and basing his opinion solely on their researches, concludes not only that there is no gradual transition, but also that there was inserted a period of elevation lasting throughout the Eocene and the Oligocene. This period of elevation separates the San Jorge (Upper Senonian or Danian) from the Patagonian formation (Miocene). The reasons that he adduces for this opinion seem rather slender. His classification appears to be mainly based on the statements of Tournouer and Ameghino in regard to the relation

[Footnote] * G. Steinmann and O. Wilckens, “Kreide- und Tertiarfossilien aus den Magellanslandern,” Archiv for Zoologi, Stockholm, Band iv, No. 6, 1908.

[Footnote] † O. Wilckens, “Die Meeresablungerungen der Kreide- und Tertiarformation in Patagonien,” Neues Jahrb. fur Min., &c, Beil.-Band xxi, 1905, pp. 98–195.

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between the beds with mammalian and reptilian remains (Notostylops, Pyrotherium, and Dinosaurs) to the marine beds of Ostrea pyrotherorium. His arguments do not appear to be convincing, especially as they are opposed to the observations and opinions of those geologists who actually saw the formations in the field.

To one who merely reads the statements of the various authors it appears quite possible that the whole series was deposited during a period of continuous marine transgression. At any rate, the close relationship between the Senonian and Miocene faunas in various parts of Patagonia and in other countries of South America seems to be a matter of considerable importance in this connection. This close affinity is admitted and is even emphasized by Wilckens, and it appears wholly contradictory to the idea of an elevation and palaeontological break extending throughout the Eocene and Oligocene periods.

(5.) Antarclica.

Another locality where Upper Cretaceous and Miocene sediments are found in association is East Antarctica, at Seymour Island. Here there is a distinct Senonian formation, which contains a considerable cephalopod as well as other molluscan fauna. The latter was described by Wilckens,* who classes it as distinctly Upper Senonian, and states that it has an Indo-Pacific character, together with certain elements of its own. It includes such genera as Lima, Nucula, Malletia, Limopsis, Turritella, Fusus, and Cassidaria, all of which have a large occurrence in the Miocene formation of South America.

Again, there are on the same small island fossil-bearing Tertiary rocks correlated with the Patagonian molasse of Miocene age. The junction of these beds with the Senonian appears to be indistinct. Andersson, in his paper on the geology of Grahamland, says that no discordance can be seen. Apparently the junction is to be placed in a poorly fossiliferous horizon which shows some false bedding. It is obvious that here the relationships in the Chile, Patagonia, and Magellan district are repeated; in other words, there is a distinct Senonian fauna clearly ancestral to the Miocene fauna, while from a stratigraphical standpoint no break has been found.

(6.) New Zealand.

In this country no lists of fossils which have been collected from those localities generally admitted to be rightly classed as of Cretaceous age have yet been published. It is well known that species of Inoceramus, Trigonia, Aporrhais, and Conchothyra, as well as Belemnites and Ammonites, occur in them; but no species of Mollusca similar to those of recognized Tertiary rocks have yet been recorded from them. Collections of the Cretaceous fossils from several New Zealand localities have recently been classified by Mr. H. Woods, but the results of his work are not yet available.

On the other hand, the fossils from the various Tertiary localities have now been moderately well studied, and no fewer than 751 species of Mollusca, excluding cephalopods, are classified in Suter's “Hand-list of New Zealand Tertiary Mollusca,” 1915. Amongst this large number of species the only two which may be regarded as possessing Mesozoic affinities belong to the

[Footnote] * O. Wilckens, “Die Mollusken der antarktischen Tertiärformation,” Wiss. Erg. schwed. Sudpolarexp., Bd. iii, Lief. 13 (1911); “Handbuch der regionalen Geologie,” 15 Heft, Band vii, 6, pp. 7, 8.

[Footnote] † J. G. Andersson, Bull. Geol. Inst. Univ. Upsala, vol. 7, p. 60.

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genus Trigonia. There is, however, at Brighton, twelve miles south of Dunedin, a pebbly, hard shell-bed containing a belemnite, which rests almost directly on the coal. This shell-bed has been classified by Hector, Hutton, Park, and others as of Tertiary age. The belemnite has not yet been accurately classified. Hector called it Belemnites lindsayi, though he afterwards suggested that it might be classed with Acanthocamax (Actinocamax) of Miller. Specimens sent by me to Otto Wilckens, of Jena, were submitted to specialists in Europe, who stated that they were too much rolled for accurate description, but they were certainly specimens of a true belemnite. The two Trigoniae and this belemnite are the only Cretaceous types hitherto admitted to occur in Tertiary rocks in New Zealand. It is, however, true that the collections of Tertiary fossils have been almost entirely made from the upper beds, as the lower are generally quite destitute of fossils.

(v.) Wangaloa.

In those localities where these lower beds are fossiliferous very small collections have been made. One of these localities is Wangaloa, situated on the east coast, about seven miles to the north of the mouth of the Clutha River. These beds were first classed by Hector in 1872 as Upper Tertiary Hutton in 1875 classed them as Pareora (Miocene). In 1910* Suter described a fossil from this bed as Turritella semiconcava. He states that Park, from whom the fossil came, has classed the bed as Cretaceous because of the occurrence of Conchothyra, Belemnites, and Aporrhais. Park, in the “Geology of New Zealand,” 1910, classes the Kaitangata coal-measures, in which the Wangaloa beds occur, as Cretaceous. Hector referred to them more fully in the Geological Survey Reports, 1890–91, p lviii, and placed them in his Cretaceo-tertiary as a lower horizon than the Ototara stone.

No lists of species have yet been recorded from this locality. The one given here does not pretend to completeness, though some two days were spent in collecting. The fossils occur in concretionary masses in a calcareous sandstone with some glauconite. These concretionary masses often unite and form a continuous stratum in the quartz grits. There is a general agreement that the horizon is a little higher than the Kaitangata coal.

In the collections that were made the following fifty-two species were found. They have been classified by Mr. H. Suter, to whom I am deeply indebted, for without his aid the precision of the identifications would be much less complete, and the lists would have a much smaller value. I give the list as I received it from Mr. Suter—

  • Gibbula n. sp, near G strangei A. Ad.

  • Minolia sp.

  • Bittium n. sp?

  • Cerithiosis n. sp?

  • Turritella symmetrica Hutton.

  • Struthiolaria (Pelicaria) n sp

  • Struthiolaria n. sp Perhaps young shells of the above.

  • Natica australis Hutton.

  • Polinices gibbosus Hutton.

  • Ampullina n. sp

  • Architectonica n sp

  • Niso neozelanica Suter

[Footnote] * H. Suter, Trans. N.Z. Inst., vol. 43, 1911, p. 595.

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  • Euthriofusus n. sp

  • — n. sp.

  • Latirus (Mazzalina) n. sp.

  • — n. sp., near Leucozonia straminea Tate.

  • Siphonalia compacta Suter?

  • Cominella n. sp., near C. lurida Phil.

  • Phos n. sp.

  • — n. sp., near P. liraecostatus T.-Woods.

  • Turris sp. ind.

  • — n. sp.

  • — n. sp.

  • Surcula fusiformis Hutton.

  • Daphnella n. sp.

  • — n. sp.

  • Actaeon n. sp.

  • — n. sp., near A. ovalis Hutton.

  • Pupa n. sp.?

  • Avellana n. sp.

  • Cylichnella enysi Hutton.

  • Roxania n. sp.

  • Haminea n. sp.

  • Dentalium mantelli Zittel.

  • pareorense Suter.

  • Nucula sagittata Suter.

  • Malletia n. sp.

  • Glycymeris n. sp.

  • Cucullaea alta Sow.

  • Limopsis aurita Brocchi, juv.

  • Venericardia difficilis Desh.

  • zelandica Desh.?

  • patagonica Sow.

  • Mactra crassa Hutton? Twice the size of the type.

  • Dosinia greyi Zittel.

  • Protocardia pulchella Gray.

  • Corbula zelandica Q. & G.

  • Panopea orbita Hutton.

  • Teredo heaphyi Zittel.

The species of Avellana sent to Mr. Suter is described in this volume (p. 120) under the name Avellana paucistriata Marshall. In addition to the species in this list, Turritella semiconcava Suter is abundant, and I also found Pugnellus australis Marshall and Avellana curta Marshall. The last two of these are described elsewhere in this volume (pp. 120, 121). Suter has stated on Park's authority that Conchothyra, Aporrhais, and Belemnites occur as well, but I could find none of them, though the occurrence of Belemnites in strata of the same age at Brighton makes it quite possible that this genus at least is represented.

The molluscan species in this collection thus total fifty-two, and of these the three species Pugnellus australis Marshall, Avellana paucistriata Marshall, and A. curta Marshall belong to genera which are not known to have representatives in strata higher than the Cretaceous. Of these two genera Pugnellus is usually Senonian, but Cossmann mentions no species of Avellana in strata higher than the Cenomanian. There are twenty-six other extinct species, and of these one—Roxania n. sp.—belongs to a genus not

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previously recorded among the extinct or Recent fauna of New Zealand. The same remark applies to the two species of the subgenus Mazzalina of the genus Latirus. The genera Gibbula, Bittium, and Haminea occur among the Recent fauna, but no extinct species have previously been recorded in New Zealand.

Thus, of thirty-nine genera, as many as four, or 10 per cent, are extinct in New Zealand. Of the fifty-two species, twenty-nine, or 56 per cent., are not represented among the 751 Tertiary species previously known. Only twenty-one species, or 40 per cent., occur among the previously described Tertiary species, and, of these, seven, or 13.5 per cent, are Recent. The Recent species are: Turritella symmetrica, Natica australis, Venericardia difficilis, V. zelandica, Dosinia greyi, and Corbula zelandica.

This analysis of the Wangaloa fossils shows that the fauna is a very peculiar one, and it is difficult to state the age of the strata in which such an association of organisms occurs. On the one hand, the occurrence of Pugnellus and Avellana shows an affinity with the Chico and Quiriquina fauna and with the Patagonian fauna of Senonian age. It is true that amongst the fauna of these localities Eriptycha or Cinulia occurs with the Pugnellus, but the replacement of these genera by Avellana merely emphasizes its Cretaceous affinities, for there is no previous record of this genus in strata higher than the Cenomanian.

The suggestion of an earlier age than the ordinary Tertiary of New Zealand is further supported by the very high number (56 per cent) of species which had apparently become extinct before the ordinary Tertiary strata of New Zealand were deposited.

The fact that Roxania and Mazzalina also occur, though unknown in the Tertiary or Recent of New Zealand, lends further support, as well as the fact that Niso has hitherto been recorded only from the low Tertiary greensands of Wharekuri.

On the other hand, the 40 per cent of New Zealand Miocene species closely relates the Wangaloa beds to that age, and this point is further emphasized by the occurrence of 13.5 per cent. of Recent species.

(w.) Hampden.

The strata at the north end of the Onekakara Beach, near Hampden, have long been known to be fossiliferous. Mantell, in 1851, classed them as Upper Tertiary. Hutton, in 1875 and in 1885, placed them in his Pareora formation, of Miocene age; and the same was done by Park in 1905 and in 1910. McKay alone, in 1887, classed them as Cretaceo-tertiary, basing his opinion on purely lithological and stratigraphical grounds.

Both Hutton and Park have given lists of fossils from this locality. That of Hutton included Trigonia pectinata Lam; but the specimen obtained by him has been recently examined by Suter, and he has shown that it is distinct from the Australian species, and it is now known as Trigonia neozelanica Suter. In 1905 Park failed to find this species; and even Hutton appears to have been doubtful about it, for he does not mention it in his list of New Zealand Tertiary Mollusca in 1886, and failed to find any more specimens when he visited the locality in that year.

In October, 1915, a visit was paid to Hampden, and no fewer than three specimens of a Trigonia distinct from T neozelanica were found. In addition, a species of Avellana was obtained. This species is described elsewhere in this volume (p 121) as Avellana tertiaria Marshall. The stratification

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of the Tertiary rocks of this coast is correctly described by McKay, as follows:—

  • (4.)

    Onekakara sands (Trigonia, Avellana).

  • (3.)

    Moeraki boulder beds.

  • (2.)

    Katiki Beach beds.

  • (1.)

    Sandstones and conglomerates with coal.

These strata McKay thought to be conformable, and there does not seem to be any reason to doubt the truth of this statement. In the upper division of No. 1 McKay found fossils that were not named, but were said to be typical species of the New Zealand Cretaceous. No fossils have yet been found in this district in the beds between (1) and (4), in the latter of which there are the two Cretaceous genera mentioned, but also a considerable number of Miocene and even Recent forms. The latter in Hutton and Park's lists amount to as much as 48 and 41 per cent. respectively. Here, then, two genera usually decidedly Cretaceous survived until the fauna had become of a definite Miocene type. This statement is made in accordance with the work of Hutton and Park, as my collections have not yet been worked out. It is, however, noticeable that Surcula hamiltoni Hutton, which has hitherto only been found in the greensands below the limestone at Wharekuri and Waihao, is well represented in my collections, though it is not mentioned in the other lists.

It is, of course, the case that Trigonia is found in the Australian Tertiaries, especially in the Janjukian, and it is also a Recent genus on the Australian coast. The Janjukian formation has been placed by Pritchard and Hall in the Eocene, and by Chapman in the Miocene period.

This collection at Hampden is particularly interesting in view of the results stated by Wilckens in Chile and Patagonia; in fact, the occurrence of these forms would probably cause him to class the Hampden formation as Cretaceous.

(x.) Brighton.

This locality lies twelve miles to the south of Dunedin. Here the quartz gravels at the base of the Tertiary rocks with coal strata rest on an eroded surface of schist. For many years the belemnite previously mentioned has been known to occur in these beds, but no other fossils in a state of preservation that allowed of identification had been obtained from it. A new species of Pecten has now been found. There are, in addition, many remains of Ostrea and a fragment of Venericardia. There can be little doubt that this bed is of the same age as the Wangaloa strata, from which it is thirty miles distant. Every geologist has up to the present time admitted its Tertiary age, and it is certainly almost at the base of the Tertiary series.

Thus in these three localities—Wangaloa, Hampden, and Brighton—all close to the base of the younger series of rocks, there are faunas which together include the following species with decided Cretaceous affinities: Pugnellus australis Marshall, Avellana paucistriata Marshall, Avellana curta Marshall, Avellana tertiaria Marshall, Trigonia neozelanica Suter, Trigonia n. sp, Belemnites lindsayi Hector.

The occurrence of these fossils would apparently be sufficient to cause Wilckens to classify the beds in the Senonian, judging by his classification of the Quiriquina and Patagonian strata (see p. 112). He has practically used the genera Pugnellus, Cinulia, Trigonia, and Baculites for assigning the Cretaceous age to these formations.

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The presence of a strong Miocene element in the fauna, on the other hand, is not destructive of this position, as in the South American localities Wilckens emphasizes the fact that the Navidad (Miocene) fauna is the descendant of the Quiriquina (Senonian) fauna, and that the Patagonian Senonian contains many elements of the Patagonian Miocene.

There is in the Wangaloa fauna, however, an important and notable fact in the occurrence of 13.5 per cent. of Recent species, and, according to Hutton and to Park, a much greater percentage of Recent species at Hampden. There appears to be no parallel for this in South America—apparently Cardium acuticostatum is the only Recent species in the Senonian.

(y.) Selwyn Rapids.

The first mention of the fossils of this locality was made by Haast.* On page 68 he gives a list of species obtained from these beds. The list includes Inoceramus, Conchothyra parasitica, Struthiolaria? as well as many other genera well represented in the Tertiary strata of New Zealand.

Cox, in 1876–77, included these beds in the Cretaceo-Tertiary, a classification that was also adopted by Hector in the same year. Haast, in the “Geology of Canterbury and Westland,” in 1879 still includes these Selwyn Rapids beds in the Waipara system, of Cretaceous age. This arrangement was also followed by Hutton in 1885, and Park, in the “Geology of New Zealand,” 1910, also groups them as Cretaceous.

The collection made for the Geological Survey by McKay, who recorded Trigonia and Aporrhais, has been submitted to Professor Woods, who, it is understood, classes them as Senonian.

A small collection was made from these beds in January, 1915, but in nearly all cases the species are too imperfect for exact identification. Mr. Suter, however, says that the following genera are represented: Panopea, Glycymeris, Myodora, Paphia curta?, Struthiolaria (Pelicaria) (good specimen), Conchothyra parasitica.

The occurrence of Struthiolaria, which was doubtfully recorded by Haast but not found by McKay, is important. This genus has not elsewhere been recorded in rocks older than the Miocene. It must consequently be concluded either that New Zealand is the home of this genus, which developed here at an earlier period than in other countries, or that in New Zealand the Cretaceous genera Inoceramus and Conchothyra lingered on until some Miocene genera had appeared. The other Tertiary genera, though very much more numerous than those of definite Cretaceous age, appear to be represented in the Tertiary rocks of other countries.

III. Conclusions.

The following conclusions are suggested by the considerations detailed in the foregoing pages:—

In New Zealand there is as yet no agreement—(1) as to the division-line between Cretaceous and Tertiary rocks; (2) as to the age of the oldest series of Tertiary strata. Various formations in Europe and America have given rise to a similar difference of opinion.

In California the Eocene rocks appear to be conformable to the Cretaceous.

Various localities in the south and west of South America have formations which have been assigned by Wilckens to the Cretaceous and to the Miocene,

[Footnote] * N Z Geol. Rep, 1871–72.

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though other authorities have considered the two formations thus classified to be conformable.

The rocks in South America described as Cretaceous contain a number of fossils which belong to genera which are well represented in the Miocene rocks of the neighbourhood.

The Cretaceous found in South America thus contains a distinct Miocene element, which may be regarded as ancestral of the Miocene fauna.

Cephalopods are either very scarce or are absent from these Cretaceous strata.

The strata at Wangaloa, Hampden, and Brighton, admitted to be near the base of the New Zealand younger series of rocks, together contain species of Mollusca similar to those which have caused the Chico, Quiriquina, and some Patagonian strata to be classed as Senonian. The Wangaloa beds in particular contain also a large number of extinct species of Mollusca belonging usually to genera well represented in the New Zealand Tertiary strata. These species include 50 per cent. of the Wangaloa fauna. There are also at Wangaloa 40 per cent. of species found elsewhere in the Miocene rocks of New Zealand, and of these some 13.5 per cent. are Recent species.

If these strata are not of Senonian age, they clearly indicate that there were several highly important Cretaceous survivals when the deposition of the Tertiary beds began in New Zealand.

If they are of Senonian age, they indicate that the Miocene fauna was already partly developed before the close of the Cretaceous.

At the Selwyn Rapids, where the strata have always been classed as Cretaceous, the distinctly Miocene genus Struthiolaria has now been definitely found.

The fauna clearly suggests that a palaeontological break between the Cretaceous and the New Zealand Tertiary either does not occur or that it is of little importance. This conclusion agrees with the result previously stated, that in the opinion of the author and of several other New Zealand geologists no stratigraphical break has been found between these formations.

These results appear to agree satisfactorily with those obtained in western California, Chile, Patagonia, the Magellan area, and Seymour Island in Antarctica.

Postscript.

The whole question as to whether the fossils and formations referred to in this paper as Miocene are rightly classed in this way is a matter that will probably be much discussed in the future. The classification as Miocene is based almost wholly on the high percentage of Recent species. It would obviously be better to use New Zealand local names for the horizons of the Tertiary rocks of this country. Thus the Wangaloa series might include all those rocks that contain from 5 to 20 per cent. of Recent species, the Waitaki series from 20 to 40 per cent., and the Wanganui series any higher percentage of Recent species.