Go to National Library of New Zealand Te Puna Mātauranga o Aotearoa
Volume 50, 1918
This text is also available in PDF
(4 MB) Opens in new window
– 65 –

Art. V.—The Stratigraphical Relationship of the Weka Pass Stone and
the Amuri Limestone
.*

[Read before the Philosophical Institute of Canterbury, 5th September, 1917; received by Editors, 31st December, 1917; issued separately, 24th May, 1918.]

Plates IVVII.
Contents.

  • Introduction.

  • Detailed Description of the Limestones.

  • Amuri Limestone.

  • The Nodular Layer.

  • Phosphatic Nodules.

  • Microscopic Description of a Typical Nodule.

  • Nodular Limestone.

  • Weka Pass Stone.

  • Historical Summary.

  • Detailed Descriptions of Important Sections.

  • Weka Pass.

  • Main Branch of Weka Creek.

  • Upper Waipara.

  • North-east Slope of Mount Grey.

  • South Branch of Omihi Creek.

  • North Side of Waikari Creek between Waikari and Scargill.

  • Gore Bay.

  • South Bank of the Hurunui.

  • On Coast South of the Blyth River.

  • Stonyhurst, in a Creek near the Homestead.

  • Motunau River.

  • Boundary Creek.

  • South Side of Amuri Bluff.

  • On Bluff North of the Mikonui Creek.

  • Near Maori Village on South Side of Kaikoura Peninsula.

  • North of Atiu Point, East End of Kaikoura Peninsula.

  • North Side of Kaikoura Peninsula.

  • Mouth of Lyell Creek, Kaikoura.

  • Puhipuhi Valley and Long Creek.

  • Contact of the Grey Marl with the Underlying Limestone.

  • Main Branch of Weka Creek.

  • Near Old Wharf, North Side of Kaikoura Peninsula.

  • East Side of Kaikoura Peninsula.

  • South Side of Amuri Bluff.

  • Evidence, that the Series is Conformable.

  • The Peculiarities of the Junction of the Amuri Limestone and Weka Pass Stone.

Introduction.

The area referred to in this paper stretches from the neighbourhood of the Waipara River in a north-easterly direction across the Hurunui River, up the coast past Amuri Bluff, to just north of Kaikoura, a total distance of

[Footnote] * We desire to state that we have been enabled to make the observations recorded in this paper largely through the award of a grant by the New Zealand Institute for research work on the phosphate-bearing rocks of Canterbury.

– 66 –

about eighty miles (see map). Throughout the region there is a great development of the Tertiary sedimentaries, and some of the localities have been looked on as classical in the discussion of various points relating to New Zealand stratigraphy. Notably is this true of the areas in proximity to the Waipara River, the Weka Pass, and Amuri Bluff, probably no parts of New Zealand furnishing better opportunities for studying the relationship of beds with a Cretaceous fauna to those with a Tertiary fauna. Nevertheless there have been and now exist remarkable discrepancies of opinion on the part of writers, and as we have had in the course of our search for phosphatic rock ample opportunities to study the relationship of the beds in different localities, and, as many miles of outcrops have been carefully examined, especially those concerning which the discussion has been keenest, we consider it appropriate to place on record the result of those observations, as far as they affect the question of the stratigraphy, in the hope that they may aid in a definite opinion as to the points at issue being arrived at.

The most important question suggested by the investigation is the matter of the conformity or unconformity of two limestones which are

Picture icon

Locality-map of part of the east coast of the South Island of New Zealand.

– 67 –

typically developed in the southern part of the area. The beds involved in this discussion are as follows, commencing from the bottom of the series:—

(1.)

Greensand.

(2.)

The Amuri limestone, an argillaceous limestone, named from its great development in the neighbourhood of Amuri Bluff, but also occurring, outside the area under consideration, in the valleys of the Clarence and Awatere, and perhaps in the south of the North Island.

(3.)

A nodular band, less than 1 ft. thick, composed of phosphatic material of two kinds in a matrix of greensand or marl.

(4.)

The Weka Pass stone, a glauconitic arenaceous limestone as it occurs in the typical locality at Weka Pass, but probably equivalent to the higher parts of the Amuri limestone elsewhere, and perhaps to the lower part of the next succeeding higher bed in localities near Kaikoura and Amuri Bluff.

(5.)

The Grey marl, in its lower portions a glauconitic, arenaceous marl, which in its higher parts in some localities becomes distinctly argillaceous and takes on a true marly facies, and at times becomes decidedly sandy as it passes up into the next higher member of the series.

There follows a more detailed description of the second, third, and fourth of these beds, which are the most important as far as this discussion is concerned.

Detailed Description of the Limestones.

Amuri Limestone.

Although the macroscopic properties of the Amuri limestone have been fully described previously by various observers and its microscopic characters have been dealt with by Marshall (1916, p. 95), it may be as well to restate its salient features in this connection.

As typically developed south of Kaikoura it is an argillaceous limestone, breaking up freely into quadrangular blocks owing to the presence of a well-defined system of cross-joints, a property which is eminently characteristic of it wherever it occurs. Owing to some of these blocks being thin and flaky, its surface takes on a tile-like appearance, especially where inclined beds are exposed on a shore-platform. This character is shown throughout the whole thickness of the limestone at Kaikoura and at Amuri Bluff, but farther south, as at Weka Pass, the so-called Weka Pass stone (the higher part of the Amuri limestone as maintained by the authors) does not exhibit to a marked degree this jointed structure, though echoes of it are undoubtedly present.

The rock is at times chalky in texture, but is usually hard and occasionally crystalline, especially where it has been subjected to pressures resulting from earth-movements. Notably is this the case at Kaikoura, where it sometimes takes on a subschistose character. Mention should be made here of the chalk deposit at Oxford, which represents this rock in the Waimakariri basin, judging from stratigraphical and lithological evidence.

The microscope shows the presence of numerous grains of glauconite even in the white-coloured rock, but distinct layers and lenticules of green-sand occur at times, as can be seen in localities like Weka Pass, though it occurs more freely farther north. At Kaikoura it occurs right through the stone, but more especially at the higher levels, where it is organized into

– 68 –

well-defined layers, this being especially the case above the zone of phosphatic nodules. Similar well-defined interstratified greensand bands are noted by McKay and by Thomson as occurring in the development of Amuri limestone in the valley of the Clarence. This is important, seeing that this higher portion, notably at Kaikoura, has been definitely recognized by various authorities as belonging to the Amuri limestone and not separated from it by any unconformity.

Another notable constituent of the limestone is flint, which occurs in lenticules and in irregular masses, as has been fully described by Thomson (1916, pp. 52–58). In Marlborough flint is specially important, but the amount progressively diminishes on being traced south. It is a well-marked constituent at Amuri Bluff and at Gore Bay, and it also occurs in the chalk deposits at Oxford, thus having a somewhat wider distribution than might be inferred from Thomson's paper. The flint is found both above and below the layer of nodules in the Kaikoura and Amuri Bluff districts, so that its presence or absence cannot be regarded as a criterion of age. Thomson has regarded the flint as formed by chemical precipitation (1916, p. 56). If that is so it must have been precipitated subsequently to the boring of the limestone, unless the boring animals have been able to penetrate flint itself, as the flint occurring in situ occasionally shows burrows filled with glauconitic material.

The lower portions of this limestone are decidedly more argillaceous, and merge into a true marl.

[The section below cannot be correctly rendered as it contains complex formatting. See the image of the page for a more accurate rendering.]

Table I.—Analyses of Amuri Limestone from Weka Pass.
(1.) (2.) (3.) (4.) (5.)
SiO2 11.12 7.52 6.74 7.25 14.45 Al2O3 1.78 1.64 1.50 0.66 1.03
Fe2O3 0.54 0.77
CaO 46.55 49.33 49.75 49.64 45.67
MgO 0.22 0.22 0.67 0.45 0.61
P2O5 0.28 0.19 0.12 n.d. n.d.
CO2 36.41 38.49 38.76 39.0 35.89
Moisture and organic matter 1.74 1.05 1.20 2.06 1.58
Alkalis, & c. 1.90 1.56 1.26 0.40
100.00 100.00 100.00 100.00 100.00
(1.)

Amuri limestone at contact, near railway viaduct.

(2.)

Amuri limestone, upper layer, same locality.

(3.)

Amuri limestone, 35 ft. below upper surface.

(4.)

Average sample, thickness of 40 ft.

(5.)

Sample 2 ft. below upper surface.

Table II.—Partial Analyses of Amuri Limestone from Kaikoura.
(1.) (2.)
Insoluble in acid 11.96 10.40
Fe2O3 and Al2O3 3.20 4.80
CaCO3 82.60 82.62
P2O5 0.57 0.51
(1.)

Sample 2 ft. to 4ft. below contact.

(2.)

Sample at the contact.

– 69 –

The Nodular Layer.

This layer is most important, as giving some idea of the conditions which obtained in the interval between the deposit of the two limestones, and therefore it will be described in detail. The most important constituent in point of volume is a calcareous greensand which fills borings in the upper surface of the Amuri limestone and passes up into the overlying Weka Pass stone, the lower parts of which are decidedly glauconitic, and there is apparently no pronounced line of division between them. Included in this matrix of greensand are numerous nodules which are more or less phosphatic, so that it may be called the phosphatic nodule bed. This nodular material is of two kinds—(1) true phosphatic nodules, and (2) nodular masses of Amuri limestone.

Phosphatic Nodules.—The descriptions of similar nodules occurring in deep water south of the Cape of Good Hope, on the Agulhas Bank, as given in the reports of the “Challenger” Expedition (“Deep-sea Deposits,” p. 396) applies so exactly that we can use the same words to describe appropriately those occurring in our own limestones. The description is as follows: “The concretions vary from 1 to 3 cm. in greatest diameter; exceptionally they may attain from 4 to 6 cm. in diameter. They are surmounted by protuberances, penetrated by more or less profound perforations, and have on the whole a capricious form, being sometimes mamillated with rounded contours and at others angular. Their surface has generally a glazed appearance and is usually covered with a thin dirty brown coating, a discoloration due to the oxides of iron and manganese.” The description further points out that grains of glauconite form a notable constituent in their composition, and especially is this the case in those from shallower water, which are larger and have a greenish-coloured external appearance. This is important, as the great majority of those found in the limestones have a greenish-coloured external appearance. The concretions are described as being hard and tenacious, “the fundamental mass, in spite of its earthy aspect, being compact, and having a hardness that does not exceed 5.” This description so fits the nodules in the greensand layer that one cannot help suspecting a similarity of origin in the two cases.

For the purpose of comparison of the chemical composition we quote three analyses—the first, of one of the Agulhas Bank nodules; the second, one cited by McKay (1887, p. 84), of a nodule from the greensand layer at the Weka Pass; the third, of a nodule collected by us at Boundary Creek.

Table III.
(1.) (2.) (3.)
SiO2 14.78 17.25
Al2O3 3.34
Fe2O3 3.87
CaO 39.58 42.17 45.90
MgO 0.84 0.72
P2O5 19.96 17.45 21.12
CO2 12.05 15.36
SO2 1.37

It is unfortunate that the second and third analyses are not more complete, but the general similarity of the results obtained will be noted.

The nodules from deeper water, as pointed out subsequently in the report (p. 393), differ from those just referred to, and the same applies

– 70 –

to those reported on by Murray as occurring in the “Bottom deposits” obtained by the “Blake.”*

The association of nodules with greensand does not, however, point to a genetic connection between the two, since nodules are found on the bottom of the present sea not associated therewith. They are of different origin and character, as may be inferred from the report on the “Blake” deposits, and as is noted in the report of the “Challenger.” The point is well brought out by Collet and Lee:—

“La glauconie et ses concrétions phosphatées se forment actuellement sur le fond des mers, existe-t-il une relation entre ces deux formations au point de vue de leur genèse? Cette question se pose naturellement quand on étudie les dépôts marins, et nous croyons être maintenant en mesure d'y répondre négativement.

“Les concrétions phosphatées sont pour ainsi dire l'image du fond dans lequel on les rencontre, ce qui prouve bien leur formation in situ. Ce fond est-il sable vert, comme dans le cas de l'Agulhas Bank, les concrétions phosphatées contiendront de la glauconie en grand abondance; est-il une boue è globigérines formée non loin du continent mais en eau profonde (3,475 mètres pour un des échantillons du Challenger), la concrétion sera entièrement formée de globigérines avec minéraux détritiques mais sans glauconie.”

Therefore the association of the greensand with phosphate nodules in the case of the limestones merely indicates that the nodules were formed on a sea-bottom at such a depth that greensands were being laid down at the same time. The depth was approximately that at which the limestones also were being deposited, as is evidenced by the interstratification of the greensand and limestone and the presence of glauconite grains in the limestone. The Amuri limestone has been shown by Marshall (1916, p. 95) to be practically equivalent to an ooze, and its chemical composition shows that it contains over 80 per cent. of CaCO3, so that it may be concluded, judging from the table given in the “Challenger” report (p. 79), that the depth was under 1,000 fathoms.

Microscopic Description of a Typical Nodule.—Under the microscope the base consists of irresolvable matter, probably calcite, with numerous tests of Foraminifera, and small fragments of quartz, feldspar, and occasionally mica. The base contains patches of microspherulitic structure, exhibiting between crossed nicols a well-marked cross with dark arms parallel to the cross-wires. They resemble to some extent small spherules of chalcedony, but from their high polarization colours they are no doubt composed of radiating fibres of calcite. There is a greenish stain of glauconite all through the slide, and the mineral at times forms distinct grains, in many cases filling the cavities of Foraminifera. These last are very numerous and constitute the bulk of the rock. The following genera were recognized: Globigerina (which is by far the most important), Textularia, Nodosaria, Rotalia. Radiolaria are also present. The glauconite is light-green as a rule, but occasionally dark-green and black aggregates also occur as a result of the peroxidation of the iron present. Small fragments of bone were also noted in one of the nodules.

Nodular Limestone.—This second class of phosphatic material consists of detached portions of the Amuri limestone included in the greensand,

[Footnote] * Bull. Mus. Comp. Zool., vol. 12, p. 52, 1885–86.

[Footnote] † Recherches sur la glauconie, Proc. Roy. Soc. Edin., vol. 26, pt. 4, p. 266, 1906.

– 71 –

which have an origin quite distinct from the true phosphatic nodules referred to previously. The nodular limestone, though easily recognized in the hand-specimen, differs little from the true nodules under the microscope, except that it is less glauconitic and approaches very closely to normal Amuri limestone. There can be no doubt that for a considerable period the limestone formed the ocean-floor (as is indicated by the phosphatic nodules), and that it was honeycombed by the borings and burrows of marine organisms operating at that depth, and that the additional phosphatic material was obtained from the ordinary limestone by a process of concentration, and from remains of those organisms responsible for the burrows. It is quite intelligible that during a period of halt in the deposition the solvent action of sea-water would cause a disappearance of a portion of the floor, and, as the phosphatic material is less soluble than the calcareous, some concentration of the phosphate would result.

This idea finds strong support in the following partial analyses of specimens obtained at Weka Pass. At this particular section the Amuri limestone is seen to be perforated to a depth of 4 ft. 6 in., the cavities being filled with the calcareous greensand that represents the overlying Weka Pass stone at this locality. The upper 18 in. of the Amuri limestone is much honeycombed with burrows, and completely detached fragments are to be found lying within the Weka Pass stone as much as 6 in. above the present surface of the Amuri limestone. It is to be understood that we look upon these nodular fragments as remnants of the original upper portion of the Amuri limestone which, during a halt in the deposition, was broken down by the combined action of boring-animals and solution by sea-water, some at least of the phosphate so set free being concentrated in the residual portions of limestone.

Table IV.
(1.) (2.) (3.) (4.)
Insoluble in acid 12.08 11.95 11.52 55.68
CaO 48.65 42.20 44.85
P2O5 0.16 0.45 4.09 1.34
(1.)

Sample 2 ft. from present surface of Amuri limestone.

(2.)

Sample from upper 6 in. of honeycombed portion of Amuri limestone.

(3.)

Detached nodules of Amuri limestone lying in the Weka Pass stone a few inches above the present surface of the Amuri limestone.

(4.)

Lower 2 ft. of Weka Pass stone.

In both types of nodules there is little difference from the associated limestone in the character of the Foraminifera and general structure of the rock, and they seem to have been formed under similar conditions. The description applies to specimens from Amuri Bluff and Stonyhurst equally with those from Weka Pass.

Under the microscope the material that fills the borings appears to be composed of much the same material as the associated limestone, and resembles in texture the Amuri limestone rather than the Weka Pass stone. There is, however, more granular glauconite, and there are more numerous shreds of mica and fragments of quartz. The glauconite does not fill the cavities in the Foraminifera so markedly, though undoubtedly some are filled. The genera of Foraminifera appear to be the same as in the Amuri limestone, Globigerina, Nodosaria, and Rotalia being clearly recognizable.

– 72 –

Weka Pass Stone.

In the typical locality near Weka Pass this rock consists of an arenaceous, glauconitic limestone. In its lower portion the rock presents the facies of a calcareous greensand of very fine grain, with a comparatively low percentage of calcium carbonate, but this percentage increases in the higher levels. (See analyses.) Specks of glauconite are, however, distributed throughout the rock. It breaks at times into quadrangular blocks, but rarely with the tily arrangement which characterizes Amuri limestone, though at times there is considerable similarity between the two rocks. Under the microscope it appears to be composed largely of Foraminifera, notably Globigerina, with a considerable amount of quartz and occasional shreds of biotite. The glauconite exists as grains, sometimes as a stain on the quartz, and occasionally filling the cavities of Foraminifera. As compared with Amuri limestone it is coarser in texture, more glauconitic and arenaceous; but the Foraminifera appear to be the same, and, as in the former case, have their cavities filled with calcareous material. The depth at which deposition took place would in all probability be slightly shallower than that at which the Amuri limestone was laid down.

Away from the typical locality the rock exhibits considerable variation. It is sometimes more glauconitic, and in fact passes into a calcareous greensand; while in other places it becomes more sandy and friable. The former of these two facies represents in all probability a deposit either in shallower water or nearer a shore-line, but there is no doubt as to its equivalence to the more calcareous rock. It is perhaps not truly synchronous, in that it may mean the gradual extension of the deposit into shallower water as physical conditions in the area changed; but the stratigraphical position and the relationship of the two facies to the underlying Amuri limestone are practically identical.

Table V.—Analyses of Weka Pass Stone.
(1.) (2.)
SiO2 34.95 22.51
Al2O3 6.44 3.92
Fe2O3 2.76 2.08
CoCO3 47.62 67.60
MgCO3 1.46 0.80
CaO 1.50 0.80
P2O5 n.d. n.d.
Organic matter and water 3.50 2.29
(1.)

Weka Pass stone 2 ft. above Amuri limestone. (Coll. J. Park.)

(2.)

Weka Pass stone, average sample “from Waikari end of Weka Pass, from cliffs N.E. of stream a few chains above the railway viaduct.” (Coll. J. Park.)

Historical Summary.

The following is a summary of the opinions held by the authors cited in the bibliography at the end of the paper, in the order of time in which they are expressed:—

Hector says (1869, p. xii), “The above (3 and 4) [grey marl] rest unconformably on blue and grey marly sandstone, sometimes passing into chalk, the formation resembling, in mineral character, the English chalk marl. In the same formation, farther north, flints occur.” There is some doubt

– 73 –

concerning the proper interpretation of the beds as detailed by Hector, but the record of cup-shaped Bryozoa as occurring in (4) evidently points to what is called the grey marl in the Waipara section, and the beds with flints to the Amuri limestone, and the grey marly sandstone to the Weka Pass stone. It is evident, therefore, that Hector did not recognize an unconformity within the beds indicated above.

Haast evidently considered the two beds of limestone as quite conformable. He says (1879, p. 297), “In some localities a break seems to occur between the upper and lower calcareous series, as, for instance, in the Weka Pass ranges, where the lower, more calcareous strata are sometimes separated from the glauconitic massive upper beds by a small band of greensand containing concretions of a more calcareous nature. However, in many other localities this small bed does not occur, and the boundary between the two series is either gradual or sharpy defined. Moreover, the upper beds are found to be always conformable upon the lower where the latter exists, being, in fact, a continuation of the same series, and, owing to the sinking of the land, of greater horizontal extent than the more calcareous beds underlying them.” We have quoted this description in full as it appears to us to explain concisely the whole case.

Hutton (1877, 1885, 1888) always maintained the unconformable relationship between the Amuri limestone and the Weka Pass stone, urging that the contact was a normal erosion-surface, and in none of his writings cited in the bibliography does he depart in the slightest from this position.

McKay (1881, 1886, 1887) considered the sequence conformable.

Thus it is that, among the older geologists of this country who have reported on this matter, three agree that the sequence is conformable, while one maintains the contrary.

We come now to the opinions of those of a more modern date. The first to be considered is that of Professor Park, who forms a kind of link with the older geologists. His views are by no means certain, and exhibit considerable evolutionary development. In his report published in 1888 he says, “As a result of the examination of many of the magnificent sections between the Weka Pass and the Waipara, I am strongly of the opinion that a complete sequence of beds exists from the base of the Cretaceo-Tertiary to the close of the Pareora formation, although the varying character of the deposits and their fossil remains show that the sea-bottom on which they were deposited was subject to frequent oscillation.” Again (1905, p. 546), he says, “Captain Hutton contends that there is an unconformity between the Weka Pass stone and the Amuri limestone. I have carefully examined the line of contact of the two rocks, but was unable to find any evidence of unconformity; and on this point my view coincides with that of Sir James Hector, Sir Julius von Haast, and Mr. McKay.” In his Geology of New Zealand (1910) Park evidently regards the two limestones as conformable, a position which he maintained in 1911 (p. 546). Next year, however, as a result of the finding of Pecten huttoni in the Weka Pass stone, he moved his unconformity to the base of the Weka Pass stone, which he then stated lay conformably under the Mount Brown limestone, although he had in 1888 demonstrated on stratigraphical grounds the existence of an unconformity between them. His position, therefore, seems somewhat obscure.

Marshall (1911, 1912) has always maintained the physical conformity between the beds of this series, and in this he has been supported by Cotton and Speight, both in conjunction with him (1911) and independently (1912).

– 74 –

Thomson also (1912, p. 8) has noted the physical conformity of the beds in the typical locality, whereas Morgan (1915, pp. 90–93), the latest writer on the subject, as a result of a hurried visit came to the conclusion that the top of the Amuri limestone presented a true erosion surface, but as the result of more complete examination of the relationship of the beds expresses himself in a less dogmatic manner (1916, pp. 17–28, and 1916A, pp. 10–11), and has evidently some doubts as to the correctness of his first interpretation, although he still agrees tentatively with Hutton and Park in his latest pronouncement.

Detailed Descriptions of Important Sections.

In order to arrive at a thorough appreciation of the problem a detailed description will be given of all localities where contacts occur from the neighbourhood of Mount Grey to just north of Kaikoura, and from the sea-coast as far inland as limestones occur which furnish any evidence. This ranges over a belt of country nearly one hundred miles in length and with a maximum breadth of fifteen miles. The localities first taken are those in the neighbourhood of Weka Pass, the typical locality; then those near the Waipara River and Mount Grey. They are followed north-east to Cheviot, when a return is made along the coast by way of the Hurunui mouth, Stonyhurst, and Motunau; and the series concludes with those at Amuri Bluff, Kaikoura, and the Puhipuhi River. We do not think that any important locality in that area has been omitted from consideration. It will be noticed that there is a general similarity of the sections throughout the area, both in its length and its breadth, which the advocates of unconformity will find difficult to explain, while the evidence for conformity is particularly strong.

Weka Pass.

Good contacts can be seen at various places in the neighbourhood of the pass—e.g., on the roadside just past Seal Rock, in the little gorge near the viaduct, on the northern face of the escarpment just east of the viaduct, and on both sides of the denuded anticline to the west of the viaduct. (Plates IV and V.) The following description fits in each case:—

(1.)

Amuri limestone: White, and jointed into flaky quadrangular blocks, the upper 2 ft. or more being bored by marine worms and the casts filled with glauconitic limestone. The amount of boring increases progressively upward till what may be called the transitional layer is reached.

(2.)

Transitional layer: This consists in its lower part of Amuri limestone material thoroughly bored, with the interstices filled with glauconitic limestone. The result of boring increases progressively, and the quantity of glauconitic material also increases pari passu. The upper 6 in. is completely bored, so that peninsulas of Amuri limestone project at times into the overlying glauconitic layer, and at times become detached and resemble subangular pebbles in appearance. They are more phosphatic than the underlying limestones, and the included glauconitic limestone is more phosphatic than the overlying glauconitic layer. The number of residual fragments of limestone decreases till they are entirely absent from the distinct layer of strongly glauconitic limestone. Included in this band are small angular nodules, green or black in colour, which are strongly phosphatic. Very occasionally, small well-rounded pebbles of quartz, about ¼ in. in diameter, are met with.

Picture icon

Plate IV.
Contact of Amuri limestone and Weka Pass stone, showing nodules of phosphatized Amuri limestone, on roadside, Weka Pass

Picture icon

Plate V.
Contact of Amuri limestone with Weka Pass stone on escarpment east of viaduct, Weka Pass Detached fragments of Amuri limestone can be seen in the Weka Pass stone

– 75 –
(3.)

Glauconitic calcareous sandstone: This is a distinct layer, about 6 in. thick, of strongly glauconitic fine-grained calcareous sandstone, which passes up into Weka Pass stone.

(4.)

Weka Pass stone: This is a distinctly glauconitic, arenaceous limestone. The green and black nodules which mark the contact appear to diminish in number on going south-west along the escarpment, but they are occasionally present and so mark a continuous horizon; but on approaching the Waipara River the difference between typical Amuri limestone and Weka Pass stone disappears, and the contact becomes indefinite—in fact, the two beds merge into one limestone without any break.

Main Branch of Weka Creek.

There is an excellent exposure of the contact in the branch of the Weka Creek north-west of the main road, just where it is crossed by the subsidiary road running from Weka Pass behind the Mount Brown escarpment in the direction of the Waipara River. The stream has in this locality cut a deep narrow gorge right across the strike, and the contacts of the Weka Pass stone with the underlying Amuri limestone as well as with the overlying grey marl are excellently shown, both being quite conformable.

In the case of the former contact we have the following sequence:—

(1.)

Amuri limestone, breaking into quadrangular blocks, with interstitial calcareous greensand in layers parallel to the bedding in its upper portions, very occasional burrows extending to 6 ft. below the actual junction. On approaching the junction the amount of greensand becomes greater, both in layers and in burrows, till near the contact the two form nearly equal proportions in the rock. Thereafter the Amuri limestone diminishes in importance, and inclusions of limestone in the greensand become rare. Dark-green and black nodules (phosphatic) as well as ironstone concretions also occur. The thickness of the layer where the two occur is about 12 in.

(2.)

Greensand layer, without inclusions of Amuri limestone, about 1 ft. in thickness, but passing up into

(3.)

Weka Pass stone in its typical development.

The contact between the two limestones is clearly seen on the escarpment to the north, and is visible at times on the south as far as a limestone knob a mile south of the creek, when for some distance towards the Waipara the junction is obscured. As far as it is visible it displays the same characteristic features.

Upper Waipara.

Excellent sections showing the relationship of the two facies of the limestone are to be seen above the limestone gorge of the Waipara River along the bold escarpment facing north-west. At the gorge itself there is the following sequence:—

(1.)

The marly facies of the Amuri limestone forms the lowest portion in this locality, and passes up into

(2.)

Typical jointed Amuri limestone with interstratified bands of argillaceous and glauconitic limestone. The upper layer of Amuri limestone is a compact white rock containing glauconite, the upper 6 ft. or 8 ft. with a concretionary fracture and passing up into

(3.)

Weka Pass stone of more than usual glauconitic character.

– 76 –

No nodules r borings are present on the line of junction, which is indistinct one rock gradually passing into the other.

Along the escarpment to the south-west the same general features are to be observed, the Amuri limestone being decidedly glauconitic at times and the greensand layer at the junction more marked than near the gorge, while the Weka Pass stone exhibits in places the typical facies, though in others it is like the Amuri limestone, and in others again it is of sandy texture, approaching a freestone, and is so friable that it can be rubbed into powder with the fingers.

At the point where shells of Pecten huttoni are found in the Weka Pass stone, which is a few chains east of the low part of the escarpment where the road crosses, the junction presents the usual features of worm-borings and the presence of scattered dark phosphatic nodules, while on the weathered surface of the Amuri limestone there are small protuberances of limestone, evidently more resistant than the remainder of the rock, and owing their preservation to the presence in them of an amount of calcium phosphate in excess of that in the surrounding rock.

When traced west the limestone outcrop passes over into the watershed of Boby's Creek, and in the bed of its most northerly tributary an excellent exposure is to be seen. This is as follows:—

(1.)

Amuri limestone, the upper 3 ft. bored more and more till the junction is reached, the borings being filled with greensand. Detached fragments of more phosphatized limestone occur along the junction. The limestone is here much thinner than it is on the escarpment to the north-east, and thins out still more when followed to the south-west towards Mount Grey.

(2.)

Nodular layer: This consists mostly of detached fragments of limestone, the true nodules being small; all are enclosed in a greensand matrix. A well-rounded pebble of greywacke was found embedded near the junction, indicating in all probability the close proximity of a shore-line. This passes up into

(3.)

Greensand, with fewer and fewer nodules.

(4.)

Weka Pass stone, more glauconitic than usual, as is usually found as the deposits approach an outstanding greywacke mass; in this case it is that of Mount Grey. In the lower part of this layer shells of Pecten huttoni were found in a somewhat poor state of preservation.

The strike of all the beds is north-east and south-west, with a dip to the south-east of 35°.

No evidence of unconformity, excepting the pebble, is given by this locality, although it affords ample opportunity for locating one did it exist. The interstratification of glauconitic limestone in the Amuri stone indicates that no great change in depth occurred between the deposit of the typical Amuri limestone and the Weka Pass stone, the interstratification of the glauconitic material in the former preparing the way for the final development of the pronounced glauconitic type.

North-east Slope of Mount Grey.

The fine escarpment which runs south-west through Mount Brown towards Mount Grey is deflected when it reaches the vicinity of the mass of greywacke of which the latter is composed, no doubt partially owing to earth-movements, of which there is decided evidence in the locality.

– 77 –

A well-defined fault-scarp runs along the eastern face of the mountain in a north-west and south-east direction in a line with the western margin of the depression which continues towards Heathstock and the Upper Waipara basin. On the western side of this, in the vicinity of Mount Mason and elsewhere, there is evidence of deformation where the limestones abut against the older rocks. This line of deformation evidently belongs to the series of north-west and south-east earth-fractures which are characteristic of the mountain region of Canterbury. As a result of this and related movements the Mount Brown beds and the underlying limestones are bent round till on the divide between Boby's Creek and Kowai River they strike north-west and dip to the north-east at high angles, about 70°. The edges of the beds are thus exposed, and the relations of the Amuri limestone to the beds immediately overlying it are well seen in one or two places. The sequence is here as follows:—

(1.)

Amuri limestone, of the usual type, well jointed, and not more than 25 ft. thick; it thus shows the characteristic thinning-out as it approaches a shore-line. In its upper layers it is glauconitic, and deeply bored, with the borings filled with greensand.

(2.)

Nodular layer: This is about 4 ft. wide, with pieces of limestone in a matrix of greensand. This bed is closed with a fairly well-defined layer of fragments in which limestone predominates over greensand, as if there were a partial reversion to limestone conditions when this part of the bed was being deposited. The calcareous nodules are distinctly bored, and show a marked qualitative reaction for phosphoric acid. There are occasional small, rounded, dark-greenish nodules, up to ¾ in. in diameter, but these are more important in the next bed.

(3.)

Calcareous greensand, strongly glauconitic. It appears that the Weka Pass stone takes on this decidedly glauconitic facies as it approaches a shore-line, and also the phosphatic nodules are apparently more numerous under these conditions, suggesting a resemblance to the conditions obtaining on sea-bottoms of the present day where greensands and green muds are associated with these nodules.

South Branch of Omihi Creek.

South-east of the Omihi Valley, and dividing its drainage area from that of the slopes facing seaward, lies the prominent limestone escarpment of the Cass, or Limestone, Range as it is sometimes called. On its northern side there are excellent exposures of the limestones and the underlying sands and sandstones resting unconformably on the Trias-Jura beds. Owing to a fault which runs approximately north-east and south-west, with a throw of some 1,000 ft. to the north-west, the outcrops are repeated, and we thus get two sections which show the horizon of the nodular layer. They exhibit a striking difference, however. One section has a facies which shows the proximity of a shore-line, in agreement with the fact that the Trias-Jura beds are in evidence but a few hundred yards away in the direction of the rise of the beds, whereas the other section, about a mile and a quarter to the south-east, has a facies which is characteristic of deeper water.

The first of these sections is well displayed near a small waterfall on the east side of the road which runs south past the shepherd's hut in the direction of the limestone escarpment. The typical Amuri limestone is here

– 78 –

absent, but it is represented stratigraphically by a strongly glauconitic limestone, whose glauconitic character is strongly marked in the flaky quadrangular blocks into which the stone is divided, but more strongly still in the interstitial portions. A well-defined layer of nodules occurs in this limestone, the matrix being a markedly glauconitic limestone. The nodules are of two types—(1) ordinary phosphatized limestone, and (2) small dark-green nodules up to 1 in. in diameter, scattered through the nodular layer and through the next 4 ft. of the bed above. The nodular layer is not so well defined as usual, but passes gradually into the beds above and below it. Worm-borings are a feature of the occurrence, and there is an entire absence of any evidence of unconformity. The whole arrangement gives a good illustration of the modification in the character of the Amuri limestone as it approaches a shore-line, and supports the contention of some writers that greensand can be laid down in comparatively shallow water.

The other type of contact showing the relations of the Amuri limestone to the Weka Pass stone can be clearly seen on the northern slope of the escarpment to the south at an elevation of between 1,600 ft. and 1,700 ft. The following is a description of the contact as seen over a considerable length of the escarpment: The Amuri limestone is from 150 ft. to 200 ft. in thickness, well stratified and jointed, divided by narrow layers of more or less marly material in the lower part and by seams of glauconitic material in the higher part, with occasional worm-borings on the top of the hard limestone layers. These borings are filled with marly material in the lower parts and by glauconitic material in the higher parts, corresponding to the character of the layer which was being deposited while the borings were being made. Glauconitic material becomes more pronounced in the higher parts till it passes into the Weka Pass stone, which is here slightly more glauconitic than in the typical locality. The sequence is perfectly conformable throughout, the limestones changing from the Amuri to the Weka Pass facies with characteristic passage beds in which the two types are interstratified along the line of junction. In some places it is difficult to tell the precise line of demarcation of the two. No nodules were seen.

North Side of Waikari Creek between Waikari and Scargill.

On the north side of this stream lies a prominent band of limestone with a west-south-west strike, dipping south-south-east. It is a remnant of a more extensive covering sheet of Tertiary sedimentaries which has been faulted into a position less exposed to destructive agents as a result of earth-movements which have affected the whole region. The main fault-line follows approximately the line of the stream-valley, but a number of subsidiary faults running parallel to this on its northern side are plainly in evidence in the upper basin of the Scargill Creek, where there are a number of parallel belts of limestone, generally dipping south-east, the repetition of the outcrops being directly attributable to this series of faults. The steep scarps face north-west, and they give good opportunities for examining the limestone through its whole thickness. Specially good exposures occur on the north side of the high escarpment behind the greywacke barrier which divides the Scargill basin from the Waikari Valley, and fronting the stripped surface of greywacke which separates the former from the Culverden basin. The section shows that the limestone band is composed of alternating layers of more or less glauconitic material, some of which, usually the less glauconitic, have the jointing characteristic of the Amuri limestone, while

– 79 –

other layers have the Weka Pass stone facies. Worm-borings are found at various levels, and very occasional nodules are sporadically distributed.

Rock of similar features is to be seen on the north bank of the Waikari Creek about two miles below the Waikari Township. In this place fragments of whale-bone occur in rock of the Weka Pass type.

There is no evidence in either of these localities of any break in the succession, the whole being certainly conformable. Although there is some variation in the lithological character of the rock from that in typical localities, yet there is no reason to suppose that it has not been formerly in close lateral continuity with the masses on the south side of the valley which show the typical differentiation into stone of two facies. There is just the difference that one would anticipate were the beds north of the Waikari deposited in an area in closer proximity to a shore-line than that in which the beds were deposited in the main Waipara, the Weka Pass, or the Cass Range areas. The fact that the sequence is unbroken in what appears to be a shallow-water facies, where one would anticipate breaks, supports the contention that the deeper-water beds are conformable.

Gore Bay.

An interesting locality is Gore Bay, near Cheviot, where sections are well exposed on the cliffs along the shore and on the southern side of the gorge which the Jed River has cut along the line of junction of the grey-wackes and the overlying Cretaceous and Tertiary beds. These latter are bent up into a well-marked syncline, which forms such a characteristic feature of the cliffs behind the sandhills of Gore Bay. Faulting is common, and on the southern wing of the syncline this has resulted in considerable crushing and brecciation along the belt of movement; nevertheless the relations of the beds are clear. The Amuri limestone in its typical facies is somewhat thin in this locality—about 12 ft.; but there is an underlying succession of marls with interstratified sandstone which is no doubt the equivalent of the lower part of the Amuri limestone at Kaikoura and other localities farther north and in the neighbourhood of Weka Pass. The upper surface shows a characteristic junction, with phosphatic nodules, succeeded by a calcareous greensand, the probable equivalent of the Weka Pass stone. (See Hutton, 1885, p. 271, for a similar occurrence near Stony-hurst.) There is no evidence, however, of an unconformity, the sequence throughout being entirely regular. The following is a detailed description of the occurrence in a deep washout in the cliffs about a quarter of a mile north of the disused landing-stage at Port Robinson. The beds are much crushed, but their relations in the vicinity of the line of junction are clear and characteristic. (Plate VI, fig. 1.)

Amuri Limestone.—The typical portion is about 12 ft. thick, but it is underlain by greyish marl. Borings begin about 3 ft. below the upper surface, but they increase in number till the contact is reached. The cavities are filled with greensand.

Nodular Layer.—This is 6 in. to 8 in. thick. The nodules are in a matrix of greensand, some being of phosphatized limestone, the other more characteristic ones varying in colour from light green through olive-green to dark green and black.

Calcareous Greensand.—This is the probable equivalent of the Weka Pass stone. It is strongly calcareous, and contains nodules sporadically up to 3 ft. above the junction. Some of these have the external appearance of greywacke but are distinctly phosphatic, and are dark green in colour. They are up to 2 ½ in. in diameter, but numbers of them are small.

– 80 –

An exactly similar section occurs on the north wing of one syncline where the road comes down on to the beach near the old lime-kiln. This locality is also noteworthy since the limestone contains abundant nodules of flint. There is no evidence of unconformity. A similar junction occurs on the steep scarp facing the Jed River, but farther north-west, on the south side of the road leading to Cheviot, we were unable to locate it definitely owing to the covering of grass where the loose greensand had been removed; but the borings in the limestone were noted in various places, so no doubt a similar contact exists there as well.

South Bank of the Hurunui.

On the south bank of the Hurunui, half a mile up-stream from the lowest bridge and about a mile from the sea, the whole series from the greywacke upwards is clearly exposed on the river-bluffs. The section consists of the followin:—

(1.)

Sands.

(2.)

Amuri limestone, over 50 ft. thick, with a north-and-south strike, and a westerly dip of 10°. It is of the usual character, the upper 4 ft. perforated with borings, the cavities filled with greensand. Included in the limestone are lenticules of greensand, and in the uppermost 2 ft. this condition is more pronounced, typical green nodules occurring sporadically.

(3.)

Nodular layer: This is 6 in. in thickness, the nodules being dark green to brown in colour, up to 2 in. in diameter, subangular, the whole layer being densely compacted with greensand cement.

(4.)

Calcareous greensand, soft, very glauconitic, and containing nodules scattered through the lower 2 ft.

(5.)

Calcareous greensand, 30 ft. thick. A fragment of coal 3 in. in length and 1 in. thick, lignitic in character, was noticed in this bed.

The section is closed by brown sands. Parts of the section are faulted, but where there is no evident disturbance the conformity is clearly displayed. Especially is this the case on the river-cliffs. In a cutting on the road in close proximity water-worn pebbles of greywacke are apparently involved near the junction, but they also occur in greensand 2 ft. above the junction; the occurrence is only a few feet in length, quite local, and, as the rocks show disturbance, may be attributed to fault or slip movements, since no similar phenomenon was observed elsewhere.

On Coast South of the Blyth River.

This section can be seen near the top of the magnificent limestone cliffs which form the background of the Napenape beach, one of the finest coastal scenes in New Zealand. Here old shore-platforms with beach-gravels on top occur at a height of 500 ft. The sequence exposed is as follows:—

(1.)

Amuri limestone: This strikes north-east, and dips south-east at low angles; it is probably affected by slight local folding, but, owing to slipping, the precise direction is difficult to determine; its thickness is at least 300 ft. The rock is beautifully white, compact in texture, jointed in typical fashion, but much disturbed by slips and faults owing to erosion of the shore and to natural fractures. A small mollusc shell was found in the upper layer, which has been identified by Mr. Suter as a variety of Pecten williamsoni.

– 81 –
(2.)

Greensand layer: This is loose, calcareous but strongly glauconitic, 8 ft. thick, without nodules as far as could be seen on the face of the steep cliff, and passing up into

(3.)

Glauconitic arenaceous limestone, 12 ft. thick, resembling Weka Pass stone but rather more sandy.

(4.)

Grey marl: This succeeds (3) with perfect conformity. Its thickness cannot be estimated, since the highest shore-platform has been cut in it.

The upper layer of Amuri limestone contains borings filled with greensand, and the marl also contains borings filled with marl.

Stonyhurst, in a Creek near the Homestead.

This place was visited in order to obtain observations of the section recorded by Hutton (1885, p. 271). It is unfortunate that he does not give the precise locality, but a careful examination of the creek in the neighbourhood of the station showed that only one section in the course of the stream was possible, and a description of this is given below. Hutton's remarks are, however, very important. He says, “Here the Amuri limestone is overlain by grey sandstone, probably the representative of the Weka Pass stone. Between the two rocks is a bed of conglomerate formed by sub-angular pebbles of slate. At first sight all three appear to belong to one system, but a close inspection shows that the surface of the limestone is fissured, and that the sandstone penetrates through the conglomerate into the limestone. This, however, may be due to chemical erosion.”

The special importance of these remarks is that they contain a record of pebbles of greywacke along the junction; it is extremely likely that these pebbles are phosphatic nodules, since at times the latter closely resemble greywacke in external appearance. It is unfortunate, therefore, that Hutton's precise locality cannot be determined.

In the creek near the homestead the beds lie very flat, and are obscured by surface accumulations and vegetation. At one place a clear section was seen, the only one occurring in the creek. Its record is as follows:—

(1.)

Typical Amuri limestone, striking north-east, and dipping south-east at an angle of about 25°.

(2.)

Nodular layer, 6 in. thick, with the usual characters.

(3.)

Calcareous greensand. This passes up into

(4.)

Weka Pass stone of more than usually glauconitic character.

The locality is disturbed by faults, but away from the disturbance the dip and strike of the Amuri and greensand limestones are identical.

Motunau River.

An excellent section through the whole series is to be seen in the lower course of the Motunau River, and the limestones are well exposed in its limestone gorge about two miles from the sea. The beds strike here north-north-east, and dip east-south-east at an angle of 20°, the whole being absolutely conformable. The sequence is as follows:—

(1.)

Amuri limestone, with typical macrostructure, its estimated thickness being 300 ft., the upper 4 ft. with borings filled with greensand.

(2.)

Nodular layer, 3 in. to 4 in. thick, composed of subangular nodules in a matrix of greensand; the nodules are up to 3 in. in diameter, dark-blackish-green in colour, with brown shade inside (? Hutton's greywacke pebbles).

– 82 –
(3.)

Greensand, 25 ft. thick with sporadic nodules in the lowest 2 ft., more thickly distributed near the junction. This passes up with occasional more marly or arenaceous layers into arenaceous limestone (Mount Brown limestone); passage beds are well developed along the junction.

Boundary Creek.

Boundary Creek, which lies midway between Stonyhurst and Motunau, was also examined, since McKay (1881, p. 111) records a good section there. The exposure was found to be very unsatisfactory owing to slips, although probably it was in better condition when McKay described it nearly forty years ago. The Amuri limestone appears to be about 20 ft. thick, but the exact contact with the overlying beds is not visible at present. Large blocks of greensand also occur in the bed of the stream, showing plentiful subangular nodules similar to those in the Motunau, associated with borings filled with greensand, no doubt near the actual junction. McKay does not mention this greensand layer, and says that grey marls immediately overlie the Amuri limestone. Judging by the dip, the limestone is in a conformable position under the top beds of the series, which have a general synclinal arrangement with the eastern limb towards the present coast-line; but there are local variations in dip well displayed on the sides of the deep gorge which the stream has cut through the non-resistant sands and marls which close the Tertiary series in this locality. It is noteworthy that McKay considers the sequence below the Motunau beds to be perfectly conformable, although he places a stratigraphical break immediately at the base of these beds, a conclusion which appears to us not warranted by observations of dip and a general examination of the section both here and in the Motunau River. The similarity of the sections in the two localities is most marked, and the evidence available from one supports that from the other.

South Side of Amuri Bluff. (Plate VI, fig. 2.)

The Amuri limestone is much jointed into flaky quadrangular blocks something like a tiled roof; it strikes north-east, and dips south-east 30°. The top 4 ft. are bored through and through with tubes which are well filled with calcareous greensand, the phenomena being progressively more marked as the upper surface is reached, where the rock is completely honey-combed and the fragments are detached. These are from 1 in. to 3 in. in diameter and are also completely bored. From this level upwards the pebbles decrease in importance and the greensand increases. All through the greensand layer nodules occur, which become smaller in the upper portions; the thickness of the greensand layer is about 2 ft., and the nodular portion where the structure is most marked is about 1 ft. thick. Above the greensand layer the rock passes gradually upward for about 3 ft. into typical Amuri limestone. The nodules of the upper layer are markedly phosphatic, while those of the lower layer are only slightly so; the phosphatization apparently diminishes progressively from the nodular layer. There are numerous sharks' teeth and occasional bones (? whale-bone) in the nodular layer.

On Bluff North of the Mikonui Creek.

The bed is exposed on the face of the cliff immediately to the north of the point where the track rises over the shoulder of the spur to escape high tides. Here we have the following sequence: First, typical Amuri

Picture icon

Plate VI.
Fig. 1.—Contact of Amuri limestone with greensand layer containing phosphatic nodules, Port Robinson. A small fault is also apparent.
Fig. 2.—Nodular layer in Amuri limestone, south side of Amuri Bluff. The parallelism of the layers is very marked.

Picture icon

Plate VII.
Fig 1 —Nodular layer in Amuri limestone, Maori village, Kaikoura Peninsula. The dark, flat surface marks a fault almost parallel to the strike.
Fig. 2.—Nodular layer in Amuri limestone, Atiu Point, Kaikoura Peninsula. Note the parallelism of the beds

– 83 –

limestone, followed by greensand with inclusions of Amuri limestone, 5 ft. thick in one place, and containing distinctly angular, black phosphatic pebbles. In some parts of the contact the Amuri limestone has inclusions of greensand, the latter being in relatively small amount. This is succeeded by 12 in. of nodular layer of the usual type, and followed then by glauconitic limestone with small green nodules and black nodules. As the band is traced north and south from the point under consideration the greensand is not so prominent but is mixed with Amuri limestone, which is especially glauconitic on or near the junction.

Near Maori Village on South Side of Kaikoura Peninsula. (Plate VII, fig. 1.)

The contact is well exposed in this locality on the raised shore-platform which covers a large area on the south side of the peninsula. The following sequence in ascending order occurs here:—

(1.)

Amuri limestone, of the usual type, but rather more flaky than jointed, perhaps the effect of faulting.

(2.)

Fault, almost parallel with the strike, with a small but increasing throw when followed to the south-west.

(3.)

Calcareous greensand from 8 in to 10 in. thick, showing honey-combed borings filled with glauconitic limestone, together with masses of greensand of irregular form. The lower part is filled with cavities, some of the worm-bored type, while others are much larger and irregular in form, the whole being filled with a uniform type of calcareous greensand. In the upper portion the worm-casts and greensand masses are smaller.

(4.)

Nodular layer: The nodules are green and black, and the structure is very well developed, so that the intervening spaces are small. These are filled with calcareous greensand.

(5.)

Glauconitic limestone, 4 in. to 5 in. thick.

(6.)

Greensand, ½ in. thick.

(7.)

Glauconitic limestone, rather more glauconitic than (5), 5 in.

(8.)

Greensand, 1 in.

(9.)

Glauconitic limestone, more glauconitic in the lower layer but passing up into one which is less glauconitic, 10 in.

(10.)

Limestone, of Amuri type, with flints, 6 in.

(11.)

Glauconitic limestone, with only a small amount of glauconite.

(12.)

Amuri limestone as typically developed, 120 ft. in thickness.

This section shows no sign of unconformity.

North of Atiu Point, East End of Kaikoura Peninsula. (Plate VII, fig. 2.)

The contact is well displayed in this locality on the shore-platform at the base of the cliffs and on the cliffs themselves. The following is a description of the beds in immediate proximity to the contact:—

(1.)

Amuri limestone.

(2.)

Calcareous greensand: The rock is bored in the usual manner and the interstices filled with calcareous greensand, and becomes more glauconitic upwards, and contains nodules green in colour, irregular in shape, up to ½ in. in diameter. This merges gradually into the nodular layer.

(3.)

Nodular layer, consisting of phosphatic nodules, more continuous than usual, the progressive development being more marked, the nodules being in a cement of calcareous greensand.

(4.)

Limestone, 2 ½ in. thick, with nodules in small number.

– 84 –
(5.)

Calcareous greensand, 2 ½ in. thick, well bedded.

(6.)

Glauconitic limestone, 8 in.

(7.)

Greensand, 3 in.

Above this there are regularly distributed layers of calcareous greensand and glauconitic limestone throughout the next 3 ft. above the nodular layer, and this is followed by

(8.)

Amuri limestone, with flints, the lower 10 ft. of which is bedded in layers which are more or less glauconitic, which finally passes up into typical stone striking north-west, and dipping south-west 10–15°.

All the layers of this sequence are much folded, the intensity of the deformation being of the same order in each case.

The same beds are seen on two other cliffs north of Atiu Point where the strata strike almost parallel to the shore-line but with acute minor folding. The nodular bed is 8 in. to 10 in. thick, with the same general features as before; the greensand layers are, however, between thicker beds of limestone above, but underneath are the same as usual.

The nodular layer also occurs on the shore-platform in this locality, but is much contorted and separated by faulting from the main layer.

North Side of Kaikoura Peninsula, on the Shore-platform between the Old and New Wharves.

This occurrence has not been noted previously, as it is somewhat difficult to locate. The limestone in which it occurs is much folded and contorted, but where the contact occurs the strike is north-east, and the dip south-east at an angle of 50°. The following is the sequence as here shown:—

(1.)

Amuri limestone, flaky in general, but subschistose occasionally owing to the movements of the beds, and with crystalline texture. The upper 6 in. of the limestone contains a considerable amount of flint, some of which contains calcareous greensand in borings, an extremely important point bearing on the origin of the flint.

(2.)

Nodular layer, 6 in. thick, with nodules in a glauconitic matrix but less rich in nodules than usual, and succeeded by

(3.)

Glauconitic limestone and calcareous greensand in alternate layers, the former 3 in. and the latter ½ in. in thickness. The lowest 3 ft. contain small and typical green phosphatic nodules. Thereafter the layers of glauconitic limestone are thicker, but still alternate with narrow bands of calcareous greensand to a depth of 20 ft. to 25 ft. It should be noted that at one spot three angular pebbles of basalt 2 ½ in. in diameter were found. These may have been of contemporaneous origin, but more likely were embedded at a later date, as others were found loose.

Mouth of Lyell Creek, Kaikoura.

The contact of the typical Amuri limestone with the overlying stone of the Weka Pass facies is to be seen close to the mouth of Lyell Creek on the northern side of the Kaikoura Peninsula. It is on the western wing of the anticline which forms the main mass of the peninsula. The beds strike here east-north-east, and dip north-north-west at an angle of 20°, the agreement between the two facies of the rock being complete.

The following is a description of the contact as far as it can be seen; at the time of our visit it was unfortunately partly obscured by a covering of beach shingle.

– 85 –

The underlying beds are of Amuri limestone as typically developed, very white, with flaky jointing and nodules and masses of flint, and with borings filled with greensand. Over this lies, with the intervening beds obscured by gravel, a glauconitic limestone, with inclusions of Amuri limestone which is decidedly phosphatic, the thickness being uncertain but certainly not more than 3 ft., the upper portion containing more of these than the lower part. It is succeeded without any unconformity by a much more glauconitic limestone—in fact, a greensand—from 6 in. to 8 in. thick, containing borings, and also small, dark, oxidized nodules. This is followed by a glauconitic limestone, also with nodules, which become smaller and smaller in the higher levels. The glauconitic character is very marked, with a concentration of the glauconitic material in well-defined layers; and borings filled with more highly glauconitic material occur throughout the whole thickness of the bed. This is succeeded in about 30 ft. (?) by the ordinary type of Amuri limestone, which very occasional glauconitic layers. No flint was observed in the upper part of the limestone. The whole section is strongly reminiscent of that at Weka Pass.

Puhipuhi Valley and Long Creek.

The limestone up the Puhipuhi Valley and that occurring up Long Creek on the southern side of the Hapuku River were also examined in order to see if any similar horizon occurs marked with phosphatic nodules, but with unsatisfactory results. The best exposure that was encountered was in a cutting just past the bridge over the Clinton River, a similar junction, somewhat obscured, being observed in the gorge of the Clinton River itself. The beds in this locality are much folded, and have suffered crushing as a result of folding and faulting movements, so that their stratigraphy is not clear. In the road-cutting to the north of the bridge the beds strike east-north-east, and dip north-north-west at an angle of 60°. The ordinary Amuri limestone is succeeded by layers of calcareous greensand, the layers being more or less glauconitic through about 15 ft., some being distinctly greensand. This is succeeded by hard greyish-green arenaceous limestone, well jointed, and with bands of more greenish tint running through it. It is much crumpled and faulted, and at least 70 ft. thick, and passes up into layers of more arenaceous character. This limestone is decidedly phosphatic. There is a strong similarity to the beds exposed some ten miles away at Lyell Creek, but no nodules of phosphatic nature were met with. Although they are apparently absent, it seems quite reasonable to maintain that the junction is on the same horizon. There is no evidence of unconformity.

Contact of the Grey Marl with the Underlying Limestone.

Although discussion of this contact is not directly connected with the principal subject of this paper, it has some bearing on the question, and therefore a description of all the contacts noted is here included. As the grey marl is easily eroded and apt to weather readily into soil, good exposures are rare. Those examined, however, show certain features which resemble the contact of the Amuri limestone and the Weka Pass stone, notably the bored upper surface of the limestone and the presence of detached fragments of the lower layer included in the higher, and it seems reasonable that if unconformity is demanded in one case it must also be demanded in the other. A consideration of the following sections will illustrate our contention as to similarity of evidence.

– 86 –

Main Branch of Weka Creek.

This section occurs in the main branch of Weka Creek, below the small bridge on the road from Weka Pass in the direction of the Waipara River to the north-west of the Deans Range. The junction between the Weka Pass stone and the overlying marl is well seen in the bed of the creek and on the sides of the deep but narrow gorge where the road crosses. The agreement in dip is absolute, and the contact does not show any signs of unconformity. The Weka Pass stone exhibits on its upper surface the same kind of borings which mark the contact of the two limestones, but the bored zone is narrower. This is succeeded by 1 ft. of slightly glauconitic sandy marl, then by 12 ft. of slightly glauconitic sandstone, passing up into sandy marl and becoming more argillaceous higher up but still preserving something of its arenaceous nature.

Near Old Wharf, North Side of Kaikoura Peninsula.

The upper surface of the Amuri limestone is tily in character, as at Amuri Bluff, with lenticules of grey marl included in the limestone, as also there are inclusions of limestone in the grey marl, the inclusions being more phosphatic than the limestone and marl in general, which are practically free from phosphate. The marl is decidedly glauconitic near the contact, and presents all the features of a fine-grained glauconitic sandstone, the sandy facies extending for 10 ft. or 12 ft. above the contact. The contact is conformable stratigraphically, any divergence from a normal junction being due to folding or faulting.

East Side of Kaikoura Peninsula.

The general strike of the beds is north-east. The Amuri limestone is much contorted, brecciated by folding, faulted, and, as a result of these structural movements, crystalline in many parts and at times subschistose in appearance. The grey marl is folded on the same lines, and sometimes included in the limestone as a result of folding. The grey marl has been subjected to just the same intensity of deformational movement as the limestone, but it exhibits the results of these movements to a much smaller degree except at the immediate contact with the limestone, where it is subschistose in structure. The whole locality exhibits faulting, some of the major faults running north-north-east parallel to the general trend of the coast-line of the Island, but there are numerous others crossing at right angles, so that the whole locality may be described as a complex of faulted anticlinoria and synclinoria, but wherever the junction between the marl and the limestone is clear the junction is conformable. It might be noted here that Hutton's figure of the East Head (1885, p. 273) is entirely incorrect.

On the south side of the peninsula, near the Maori village, the contact is of the same character as on the north side. The Amuri limestone is slightly glauconitic, becoming more so near the junction. There is a layer about 6 in. thick where the limestone and the marl are mixed, a phenomenon which is in part due to boring. The grey marl is glauconitic in its lower part for a thickness of several feet, and contains numerous fragments of whale-bone. Along the line of contact faulting is much in evidence, the faults being both normal and reversed, with a direction in general at right angles to the strike. The figure by Hutton (1885, p. 273) is evidently given under a misapprehension of the effects of faulting, the irregular line of contact being attributed by him to erosion.

– 87 –

South Side of Amuri Bluff.

In this locality the sequence is well exposed on the finely developed shore-platform, on the south side of the bluff and around the coast-line as far as the mouth of the Okarahia Creek. Above the nodular layer there is about 15 ft. or so of limestone, and this is succeeded conformably by a greenish calcareous sandstone, perhaps the equivalent of the lower part of the typical grey marl, or perhaps, as is more likely, the equivalent of the Weka Pass stone. The upper portion passes into a typical marl of decidedly argillaceous character. Hutton considered that this locality furnished strong evidence of unconformity between the grey marl and the Amuri limestone, his main line of evidence being the discordance in the dip of the former as it occurs in the neighbourhood of the mouth of the Okarahia Creek and south of it with the limestone at the bluff. This apparent discrepancy in angle of dip is due to folding and twisting movements affecting the beds unequally in the two localities. The limestone south of the creek dips at a very high angle, and the marl is in perfect accord with this; while when traced in a north-easterly direction towards the bluff the beds flatten out, and nowhere present any evidence of discordance.

Evidence That The Series Is Conformable.

This detailed account of the sections taken from widely separated parts of the area gives some idea of the general nature of the contact and emphasizes the similarity of its features. Relying entirely on the evidence of the borings in the upper surface of the Amuri limestone and the presence of detached fragments of the limestone in the greensand matrix of the nodular layer, Hutton and Morgan came to the conclusion that it was a true erosion surface, the supposition being that the erosion took place in the vicinity of a shore-line. No palaeontological evidence was advanced by either in support of their contention as regards the two limestones, the reason being that they are both, the Amuri limestone especially, according to Hutton, almost unfossiliferous; thus in their opinion the existence of an unconformity rests entirely on stratigraphical evidence. We, however, relying on stratigraphical evidence, have come to a conclusion that the sequence is conformable, the reasons for this conclusion being as follows:—

1.

In every case there is absolute agreement in the dip of the beds above and below the nodular layer. When this occurs over a region of a hundred miles in length by some fifteen in breadth, unconformity appears extremely doubtful. It means that a limestone has been laid down on a deep-sea bottom, the rock has become consolidated, raised above the sea, eroded, and again depressed into deep water so that another layer of calcareous material may be deposited, and all this without any variation in angle due to structural movements or to conditions of deposition over hundreds of square miles. Such a contention appears unreasonable.

2.

Apart from the evidence furnished by the included fragments of limestone in the nodular layer, and the report of the occurrence of pebbles of greywacke at Stonyhurst, which can be explained as probably the result of mistaken identification, there is no evidence of erosion of the upper surface of Amuri limestone. On any present-day surface of Amuri limestone there are distinct irregularities, and especially is this the case on the shore-platforms where tidal channels, & c., are a marked feature, and none of these are to be seen at any part of the contact, although it is exposed for many miles in different parts of the area, not only parallel but at right angles to

– 88 –

the present shore-line. It would be expected that they should occur somewhere. Present-day shore-lines show surfaces of Amuri limestone with no similarity whatsoever to those associated with the nodular layer, even when those parts of the shore-platform are composed of nearly horizontal layers. Any change in the nature of the rocks due to folding and consequent induration which might be cited from the Kaikoura neighbourhood as modifying the conditions would not apply farther south, where the influence of such movements has been comparatively slight.

3.

There is no true shore or shallow-water deposit of any kind over the whole area. It is certain that during the depression demanded by the unconformists, when the surface of the Amuri limestone was lowered from forming part of a land surface or a shore-line to such a level that glauconitic limestone and greensand were deposited, beach and shallowwater beds would occur in some parts of the area. Nevertheless they are absent entirely.

4.

In many places is it impossible to determine the dividing plane between the two limestones, so gradual is the transition—that is, they furnish in some places no evidence of a break. In fact, as a general rule the upper and lower layers display such a similarity in their characters, notably in the presence of glauconite, that transitional forms are to be expected.

5.

In the case of the borings in the upper surface of the Amuri limestone, and also those in the Weka Pass stone in contact with the grey marl, the borings are filled with the material of the overlying bed, however deep they are down below the surface. If this is a greensand the tubes are filled with greensand, if a marl they are filled with marl. Also, there are cases of tubes in the body of the limestone which are filled with the material being laid down on the surface into which the borings were made. If, now, these borings were made on an ordinary beach or shore-platform they would be filled with beach deposit, and would not remain open till they were depressed to a depth at which limestone or greensand was the characteristic deposit.

6.

The remarkable uniformity in the thickness of the layer over long distances appears to be inexplicable on the basis of its being a shore-line deposit, since these are notably variable both in thickness and in the nature of their constituents. The parallelism of the upper and lower surfaces of the layer is well brought out in the photographs taken from various widely separated localities where the bed is well and clearly exposed.

7.

The analyses of the so-called “rolled pebbles” at the junction between the two layers (see page 71) shows that they are not ordinary detached fragments of Amuri limestone such as would be found on a beach, which should resemble the parent rock in chemical composition. They have certainly been modified by agencies other than those operating on a shore-line.

Morgan (1915, p. 92) cites a paper by Edward M. Kindle on “The Unconformity at the Base of the Onondaga Limestone in New York, and its Equivalent West of Buffalo”;* and remarks, “This paper describes fully an unconformity not easily detected at all points by stratigraphical evidence alone.” He uses it to emphasize the fact that an unconformity can occur between two limestones. But it seems to us that such contacts are by no means unlikely, since limestones of various ages form a notable feature of the rocks of the earth's crust, and the probability of a contact between two limestones as compared with that between limestone and

[Footnote] * Joura. Geol., vol. 21, pp. 301–19, 1913.

– 89 –

another rock of different lithological composition is in proportion as these rocks form part of the earth's crust in the locality where the limestones are being laid down. The criteria of unconformity in general, apart from the possibility of chemical erosion on the plane of contact, will be the same as between limestone and another rock. In Kindle's paper attention is drawn to the difference in dip of the two limestones in question, and to the decided surfaces of erosion of the lower limestone. The photographs that he uses to illustrate his paper are quite convincing, and show pronounced differences in the contact as compared with that between the Weka Pass and Amuri limestones, and we have seen no locality where similar pictures could be obtained from the contact of the two New Zealand rocks.

For the reasons given above the authors consider that the contact between the two limestones is not due to erosion, and that after the deposit of the lower bed no emergence from the sea took place before the second limestone was deposited. Some alteration in depth or in the conditions of deposition no doubt occurred, but they were of no greater amount than that which takes place when a bed of different lithological character is laid down in a perfectly conformable sequence.

It has been pointed out that both above and below the nodular layer there is an interstratification of greensand in the limestone, the deposition being conformable, which shows that slight oscillations of level or conditions took place. The phosphatic nodules are exactly analogous to those forming now on ocean-bottoms at depths of over 100 fathoms in association with greensand, and such do not form on a shore-line. Such nodules are frequently found in the Cretaceous limestones of Europe and America without an unconformity being demanded, although some lapse of time and change of conditions must have occurred. The phosphate nodules occurring in the Cretaceous beds of the south of England and the north of France and in Belgium usually lie at the base of the series which succeeds another after some lapse of time. In some cases, however, distinct unconformity has been demonstrated on account of the presence of pebbles and rolled fossils, the break being of more decided character and amounting to an unconformity, but in other cases there is no pronounced break.

The association of these nodules with a bored surface seems to indicate clearly that the boring took place not on a shore-line, but on a sea-bottom formed of a soft calcareous ooze before it had consolidated and hardened into rock. The borings extend to such a depth beneath the surface that it may be doubted whether it is possible for marine organisms to tunnel such a distance into hard rock, whereas if it be admitted that the boring took place before the rock had consolidated and while it was actually in process of deposition there is no difficulty. The filling of these deep tunnels with greensand, as has been pointed out, certainly suggests boring on a seabottom. Although many marine organisms have the power of making burrows, it occurred to us that they were in all probability made by marine worms, and therefore we applied to Dr. Benham for his opinion on the matter. In a private letter he says, “Unfortunately we know nothing, so far as I can find out from monographs on the Polychaeta, & c., about the burrows in deep water. When the dredge is used the surface of the mud, & c., will still be disturbed; and even if the worms are captured the walls of the burrows, if any, will fall in, and the burrow, of course, will be smashed. So that I find no reference at all to burrows of worms living beyond the littoralzone area. But we may expect that if they are formed at these greater depths they, too, will be U-shaped. You ask at what depths worms live

– 90 –

and work. Certain species have been found at as great a depth as 3 000 fathoms, though at depths below 1,000 fathoms they are much rarer than at less than 100 fathoms—that is, the great majority live along the continental shelf, and especially along the littoral area.”

This opinion is not conclusive, but it certainly indicates that it is possible for worms to produce borings at the depth at which greensand is deposited.

The statements of Cayeux (1897, pp. 431–32 and 532–33) are of interest in their bearing on this point. He shows that phosphatic nodules occur in ths chalk of France and Belgium at levels marked by change in the depth of the sea, whether this be in the direction of increasing or of lessening depth—that is, they occur at the points of inflexion of the curves indicating the depths of the sea over the area at any particular time. He says (p. 431), “La production du phosphate de chaux de la base de la craie è Belemnitelles correspond è une rupture d'équilibre de la mer crétacée, phénoméne dont on a maintes preuves.” These are then given, and among them may be noted the hardening of the upper layer of chalk and the presence of perforations. The first of these is perhaps analogous to the hardening of the fragments in the upper layer of Amuri limestone which may be attributed to phosphatization, and the second is a most characteristic feature of its upper surface. Farther on (p. 432), he says, “La craie phosphatée du department du Nord est en relation avec un mouvement d'exhaussement qui a eu pour résultat de chasser la mer du golfe du Mons. Son existence est liée è une période de régression de la mer pour le Nord.” Of the two instances quoted, the former applies to an increase in depth of the sea and the latter to a diminution in depth. The latter in all probability is analogous to the change from Amuri limestone to calcareous greensand which characterizes the level of phosphatic nodules in the New Zealand area.

Further, Cayeux considered that the accumulations of phosphatic material took place at such a distance from the shore that the change in depth of the sea did not permit of any marked variation in the character of the terrigenous material associated with the chalk. This is borne out to some extent in the area under consideration, as it has been shown that the material of the phosphate nodules is not markedly different from that of the beds with which they are associated. In any case, Cayeux does not postulate any emergence of the sea-bottom to account for phenomena which are quite analogous to those near the junction of the Amuri and Weka Pass limestones.

The Peculiarities Of The Junction Of The Amuri Limestone And Weka Pass Stone.

It must be admitted that the junction of the Amuri and Weka Pass limestones is a peculiar one and demands some special explanation, seeing that unconformity is not admitted. The irregularity of the junction in some places could be attributed to chemical erosion, and the increased amount of phosphate in the detached pieces of Amuri limestone in the nodular band supports this contention; but it may be explained in another way, or perhaps the two explanations are not mutually exclusive. It seems to us that the so-called erosion surface has been the result of extensive boring during the interval between the deposition of the typical Amuri limestone and the upper more glauconitic part of the bed when it formed part of a sea-bottom. As a result of the complete penetration by borings the upper surface consists in places of peninsulas of limestone surrounded by green-

– 91 –

sand. In places, too, these jutting portions have been completely cut off, so that they become detached fragments. Similar occurrences can be seen at times in the estuaries which are filled with calcareous mud and have been completely honeycombed by borrowing molluscs, & c. In this way an apparent erosion surface can be formed; but the character of the junction under consideration requires a uniformity of conditions over wide areas, and this would be obtained if the bored surface were a sea-bottom and not a shore-line. The increased phosphatization of the fragments of Amuri limestone, and perhaps of the true phosphatic nodules, might be accounted for by the decay of the bodies of the boring organisms, in addition to probable increased phosphatization owing to concentration by the dissolving-out of the more soluble calcium carbonate from the rock.

The remarkable persistence of the nodules of phosphatic material at a limited level in the limestone renders them extremely useful as a datumlevel for comparing the relative age of rocks in the series, and this is all the more valuable owing to the comparative absence of fossils. It may, of course, be suggested that there is more than one layer in the limestone, and that the phosphatic nodules at Kaikoura occupy a different position from those at the Weka Pass; but the whole of the attendant circumstances of the surrounding beds renders it extremely likely that only one layer exists. If the nodules had been laid down on the bed of a deep sea, then it is likely that the sea extended all over the area in question, and their synchronous formation would be very probable indeed.

Assuming that this is so, it would clearly indicate that the Weka Pass stone was the equivalent of the upper part of the Amuri limestone in the Kaikoura district and also at Amuri Bluff; but, seeing that the lower portion of the grey marl at Kaikoura and Amuri Bluff is lithologically a calcareous greensand, it is not at all improbable that Hutton was partly correct in correlating the Weka Pass stone with the grey marl, only that it is the lower portions of the marl that are equivalent to the upper layers of the Weka Pass stone. However, between the marl and the limestone in the Kaikoura region there is a junction which is analogous to that between the two limestones, in that the limestone immediately below the lowest layer of the grey marl is bored and sporadic phosphatic nodules occur in it. This, of course, indicates some break in time.

At the Amuri Bluff the thickness of the limestone above the nodular band is reduced to 15 ft. as compared with a thickness of 100 ft. or more at Kaikoura and a great thickness as exposed on the sea-cliffs between the Oaro and Mikonui Creeks. It must be mentioned, however, that as the beds are traced along the coast south of Amuri Bluff towards the Conway River they thin out and the limestones lose their distinctive features. This certainly suggests the vicinity of a shore-line, and therefore there is no improbability that the lower part of the grey marl in that neighbourhood, especially that part with sandy texture, may be the stratigraphical equivalent of the glauconitic facies of the Amuri limestone farther north, the sea evidently deepening in a northerly direction. It is probable that an easterly extension of the land, either continuous or in the form of islands, divided the Kaikoura part of the sea from that south of the Hurunui. The existence of such a land if it were of low relief would not, of course, negative the contention that a sea extended generally over the site of the present Kaikouras, and that the land had been base-levelled to some extent before being depressed and covered with a veneer of Tertiary sediments. But it must be clearly understood that the shore-lines of this land must not be con-

– 92 –

sidered as related to the present orographic features. These are, no doubt, a very late development, as demanded by McKay and by Cotton. The failure to appreciate this point thoroughly no doubt influenced Hutton, and to some extent Morgan (1916, p. 28), in attempting to fix the position of the shore-line of the Tertiary sea in that region.

Since we maintain the conformity of the two limestones, and since we can suggest no other horizon where a physical break occurs in the series under consideration, our present contention involves the recognition of the stratigraphical conformity of beds in the lower part of the sequence containing Cretaceous fossils with those higher containing Tertiary fossils. (For the latest pronouncement on the Cretaceous age of the lower members of the series see Trechmann, 1917, p. 295.) In our opinion the beds with Cretaceous fossils are definitely Cretaceous, and those higher up with Tertiary forms are Tertiary. The anomaly is accounted for by the slow and continuous deposition of the beds, so that when the period of deposition commenced the time was Cretaceous, and when it closed it was Tertiary, judging by European standards of geological time. The earlier part of this period was marked by slow depression of the land, with a corresponding change in the nature of the deposits (see Speight, 1917, pp. 350–51). During the time of maximum submergence the greensands and limestones were deposited, and as the sea-bottom was raised a reversal of the order took place with slight minor oscillations. When one considers the small area of land which was probably in existence above sea-level in the vicinity of the region under consideration, the slow rate of deposition can be readily understood. Thus during this long period of submergence of the area the local fauna had time to change from a Cretaceous to a Tertiary facies.

Bibliography.

Cayeux, L., 1897. Terrains sédementaires, Memoires de la Société géologique du Nord, Tome IV.

Cotton, C. A., 1912. Typical Sections showing the Junction of the Amuri Limestone and Weka Pass Stone at Weka Pass, Proc. N.Z. Inst., pp. 84–85.

Haast, J., 1871. Rep. Geol. Explor. dur. 1870–71, pp. 15, 25.

Haast, J. Von, 1879. The Geology of Canterbury and Westland, p. 297–98.

Hector, J., 1869. Rep. Geol. Explor. dur. 1868–69, p. xii.

Hutton, F. W., 1877. Rep. Geol. Explor. dur. 1873–74. p. 27.

—— 1885. The Geological Position of the Weka Pass, Stone, Quart. Journ. Geol. Soc., vol. 41, pp. 266–78.

—— 1888. On Some Railway Cuttings in Weka Pass, Trans. N.Z. Inst., vol. 20, pp. 257–63.

McKay, A., 1877. Rep. Geol. Explor. dur. 1874–76, p. 36.

McKay, A., 1881. Rep. Geol. Explor. dur. 1879–80, pp. 108–17.

—— 1886. Rep. Geol. Explor. dur. 1885, p. 27.

—— 1887. Rep. Geol. Explor. dur. 1886–87, pp. 74, 78.

—— 1890. Rep. Geol. Explor. dur. 1888–89, p. 85.

Marshall, P., 1911. New Zealand and Adjacent Islands, Handbuch der regionalen Geologie, pp. 22–26, 39–41.

—— 1912. The Younger Rock Series in New Zealand, Geol. Mag. (n.s.), dec. 5, vol. 9, p. 314.

—— 1916. The Younger Limestones of New Zealand, Trans. N.Z. Inst., vol. 48, pp. 87–99.

—— 1916A. Relations between Cretaceous and Tertiary Rocks, Trans. N.Z. Inst., vol. 48, pp. 100–19.

Marshall, P., Speight, R., and Cotton, C. A., 1911. The Younger Rock Series of New Zealand, Trans. N.Z. Inst., vol. 43, pp. 378–407.

Morgan, P. G., 1915. Weka Pass District, North Canterbury, 9th Ann. Rep. (n.s.) N.Z. Geol. Surv., Parl. Paper C.-2, pp. 90–93.

– 93 –

Morgan, P. G., 1916. Notes on a Visit to Marlborough and North Canterbury, with Especial Reference to Unconformities post-dating the Amuri Limestone, 10th Ann. Rep. (n.s.) N.Z. Geol. Surv., Parl. Paper C.-2B, pp. 17–28.

—— 1916A. Record of Unconformities from Late Cretaceous to Early Miocene in New Zealand, Trans. N.Z. Inst., vol. 48, pp. 1–18.

Park, J., 1888. Rep. Geol. Explor. dur. 1887–88, p. 25–35.

—— 1905. Marine Tertiaries of Otago and Canterbury, Trans. N.Z. Inst., vol. 38, p. 546.

—— 1910. The Geology of New Zealand.

—— 1911. The Unconformable Relationship of the Lower Tertiaries and Upper Cretaceous of New Zealand, Geol. Mag. (n.s.), dec. 5, vol. 8, pp. 539–49.

—— 1912. The Supposed Cretaceo-Tertiary Succession of New Zealand, Geol. Mag. (n.s.), dec. 5, vol. 9, p. 314.

Speight, R., 1912. A Preliminary Account of the Lower Waipara Gorge, Trans. N.Z. Inst., vol. 44, p. 221.

—— 1915. The Intermontane Basins of Canterbury, Trans. N.Z. Inst., vol. 47, p. 336.

—— 1917. The Stratigraphy of the Tertiary Beds of the Castle Hill or Trelissick Basin, Trans. N.Z. Inst., vol. 49, pp. 321–56.

Thomson, J. A., 1912. Field-work in East Marlborough and North Canterbury, 6th Ann. Rep. (n.s.) N.Z. Geol. Surv., pp. 7–9.

—— 1916. The Flint-beds associated with the Amuri Limestone of Marlborough, Trans. N.Z. Inst., vol. 48, pp. 48–58.

Trechmann, C. T., 1917. Cretaceous Mollusca from New Zealand, Geol. Mag. (n.s.), dec. 6, vol. 4, pp. 294–305, 337–42.