Sediments of the Western ·Shelf, North Island, New Zealand

ISSN 2538-1016; 40

NEW ZEALAND DEPARTMENT OF SCIENTIFIC AND INDUSTRIAL RESEARCH

BULLETIN 179

SEDIMENTS OF THE WESTERN ·SHELF, NORTH ISLAND, NEW ZEALAND

by ]. C. McDOUGALL and J. W. BRODIE New Zealand Oceanographic Institute Wellington

New Zealand Oceanographic Institute Memoir No. 40

1967 Photo: Whites Aviation Ltd. western coastline from Pariokariwa Point (right foreground) to New Plymouth. Mount Egmont background. Late Pleistocene marine The terraces in foreground (Coastal Type V). n

BULLETIN 179

SEDIMENTS OF THE WESTERN SHELF, NOR TH ISLAND, NEW ZEALAND

by J. C. McDOUGALL and J. W. BRODIE

New Zealand Oceanographic Institute Wellington

New Zealand Oceanographic Institute

Memoir No. 40

1967

Price $1.25

Editor: P. Burton, Information Service, D.S.I.R.

R. E. OWEN, GOVERNMENT PRINTER, WELLINGTON, NEW ZEALAND-1967

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ PREFACE THE western continental shelf of New Zealand has, until recently, been the least known of the marginal shallow water areas around the coastline. Over the last three years a programme of sediment sampling has been carried out on part of the western shelf of the North Island. The area is large, extending from Wanganui to Kaipara, and the results have enabled the presentation in this memoir of a preliminary analysis of the nature and distribution of the surface and subsurface sediments. Three charts which detail sediments of the western shelf are being published separately. The manuscript has been prepared for publication by Mrs P. M. Cullen.

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ CONTENTS Page 7 ABSTRACT INTRODUCTION 7 Sources of Data 7 Morphology of the Area Sampled 8 The Continental Shelf and Slope 8 The Coastal Region 13 Methods of Collection .. 13 Methods of Examination and Analysis 13 System of Data Presentation 19 SURFACE SEDIMENT DISTRIBUTION 28 Grain-size Distributions along Sampling Lines 28 Zonation 29 Areal Distribution of Individual Grade Components 29 Median Diameters ...... 33 Distribution of Dominant Fractions of Total Sediment and of Titano-magnetite .. 35 SUBSURFACE SEDIMENT GRADE DISTRIBUTION 38 Distribution of Sediments in Cores 38 Subsurface Reflecting Horizons .. 39 PRESENT-DAY SEDIMENTATION 40 North of Cape Egmont 40 South of Cape Egmont .. 40 PHASES OF SEDIMENTATION 41 Stands of Sea Level 42 Relative Chronology 43 VOLCANIC COMPONENTS OF SHELF SEDIMENTS 44 ORIGIN AND METHODS OF EMPLACEMENT OF SHELF SEDIMENTS 45 ACKNOWLEDGMENTS .. 45 REFERENCES 45 APPENDIX: Grain-size Distribution along Sampling Lines 52 INDEX .. 54 FIGURES Fig. No.

1. (a) Locality Chart . . 8 (b) Sampling Lines . . 8 2. Sample positions 9 3. Bathymetry of Western Shelf 10 4. Sounding profiles across the Western Shelf 11 5. Coastal types and major rivers, West Coast, North Island 15 6. Areal distribution of groups of sediment grades 18 7. Grain-size distribution along sampling lines 20-27 8. Distribution of dominant grades in (a) total sediment: (b) magnetic fraction 30-31 9. Median diameter of surface sedin1ents along three sampling lines; (1, 7, 11) 32 10. Distribution of median diameter with depth and distance along lines 33 11. Histograms of grain-size percentages in selected surface sediments 34 12. Profiles and echo soundings of subsurfacereflectors 35-36 13. (a) Areas of quartz sands on the Western Shelf .. 36 (b) Area of prominent occurrence of dead shell and shell fragments (shown by shading) 37 14. Cross sections of sediment beds along sampling lines 2 and 9 38 15. A tentative reconstruction of the Shelf Edge time shoreline, showing the location of Egmont Gulf 42 PLATES

Frontispiece: The westerncoastline from Pariokariwa Point to New Plymouth. (Coastal Type V) 1. View north along western coastline from Muriwai to Kaipara Harbour entrance (Coastal Type I; Type 11 in foreground) ...... 12 2. View south along western coastline just south of Manukau Harbour entrance (Coastal Type III) 14 3. View north from Kawhia Harbour entrance. (Coastal Type IV) 16 4. Corer with grab as trip weight, before lowering 17 TABLES Table

I. Station List 46 2. Shelf Chronology 43 APPENDIX

Grain-size distributions along sampling lines 2-6 and 8-10 52 6

by J. McDOUGALL and J. w. BRODIE c.

ABSTRACT

Sediments at the surface of the western shelf between Kaipara and Wanganui can be separated into zones in each of which one grain size is dominant. For the shelf north of Cape Egmont an Inner Very Fine Sand Zone extending out to 25 fm is succeeded by a Fine Sand Zone out to 50 fm, then by an Outer Very Fine Sand Zone to the shelf edge. South and west of Cape Egmont an extensive Mud Zone occupies most of the shelf except an inshore area, south of Cape Egmont, in which sediments possessing a coarser dominant grade are found. The available sediment for deposition at present is mud and the coarser grades present offshore are relict fromearlier sedimentary phases of late Quaternary times. The patternof distribution of titano-rnagnetiteon the shelf suggests that it is not due to primary volcanic emplacement of the material.

INTRODUCTION

SOURCES OF DATA B.A. 1212, 2054, 2535, 2543, 3633, and N.Z. charts Sediments of the western shelf of the North 46, 4423, and 4421, were utilised to extend the data Island of New Zealand were sampled during two on sediment distribution considered here. N.Z. Oceanographic Institute cruises in the M.V. Prior to the sampling on which the present Viti in October 1959 and May 1960 (Ironsand investigation is based, no studies had been made of Cruises I and II). The area sampled extends from the shelf sediments in this area. However, analyses just south of Kaipara Heads to the mouth of the of some of the samples collected during the Iron Wanganui River, and seaward to the vicinity of the sand Cruises have been used to examine the 100 fm line, the position of which varies between distribution of titaniferous ironsand over the inner approximately 17 and 60 miles offshore (fig. 1). In portion of the western shelf (McDougall, 1961). addition a supplementary series of samples was The survey was planned to define the grade obtained in March 1963 from M.V. Taranui. distribution of the superficial shelf sediments and Sampling from M.V. Viti was carried out along to examine in lesser detail the subsurface material 11 east-west lines 20 miles apart from latitude by the use of short cores. Consideration of some of 36 40'S to 40 00'S. On each line sampling was the factors influencingtran sport and deposition has commenced as close as practicable to the shore and been possible.

successive° stations° were then worked at intervals of In March 1963, supplementary sampling (fig. 2) 1 mile to a distance of 5 miles offshore, at 2 mile was carried out along lines intermediate between intervals to 20 miles offshore, at 5 mile intervals the original lines 3, 4, 5, 6, 7, and 8, giving an to 30 miles offshore, and at 10 mile intervals to the effective interval of 10 miles between lines of shelf edge. Sampling was commenced no further samples north of New Plymouth. Between lines 8 than 2 miles offshore on most lines, the closest and 11, a series of individual samples was taken to station to shore being half a mile out (fig. 2). The extend the cover in this area. western coastline is very exposed and the circum In addition, material has been available as a stances of excellent weather and careful navigation result of earlier sampling by D. M. Garner of the greatly facilitated this sampling. N.Z. Oceanographic Institute (1959). Additional samples in the Institute collections One of us (J. C. McD.) has been responsible for taken by HMNZS Lach/an and CS Recorder the planning and fieldwork, and the discussion of together with chart notations on Admiralty charts surface and subsurface sediment distributions: the

I. MURIWAI

2. PIHA

3. WAIKATO

3a. KAPIAPIA

4. RAGLAN

4a. KARIO[

5. AOTEA

....__.______-r--� 5a. ALBATROSS

6a. TIRUA 1------+------f

7. MOKAU 7a. TONGAPORUTU

8. WAITARA

9. EGMO

10. HAWERA

Fig. I : Locality chart and sampling lines

other (J.W.B.) has contributed a commentary on less definite at 90-100 fm between Kawhia and the significance of the results in terms of late Cape Egmont, where the shelf is 60 miles wide. Pleistocene and Post-Glacial chronology. Over the area covered by lines 1-4 (fig. 1) apart from a local decrease in grade off the mouth of the Waikato River, the average inclination of the shelf MORPHOLOGY OF THE AREA SAMPLED is 0 17'. The Continental Shelf and Slope: A general bathy Further south (lines 5-11) the shelf has a more

metric chart is presented of the total area sampled irregular° undulating surface and its width is con (fig. 3). This has been compiled from chart sound siderably greater, the average inclination is less, ings, from station depths (based on length of being about 0 04', except in an area just off Cape wire used) and from a limited number of echo Egmont. Here the 50 fm mark is reached 6 miles off

soundings. shore, and the °100 fm line 60 miles offshore. From Kaipara to Kawhia the outer limit of the Thus two major morphological regions exist on shelf lies in depths between 70 and 80 fm about 30 the western shelf between Kaipara and Egmont. miles offshore. The break in slope at the shelf edge Echo-sounding profiles in the northern region show is sharply definedin this northern area, but becomes that the outer portion of the shelf is steeper than the

Line I: Muriwai

Line 2: Piha

Line 3: Waikato omoa��a�

�� le 0 � � 0 0

� �;i� Line 4: Raglan � aaa 0 o:x, .... .,"� � 0 0

Li e o J 38, 1------+-- _ n_ _S_: _A_ _ te_ _a______"' � " "� : ,f ,._.:- cf 'v 0

,., :;, ,-,' C'.. C'� C' {;f.." Line 6: Marokopa 0 .;;-0 0 oC' 0 'V 0 �"' .,� .,,f �,g, 0 0 30 $/ Line 7: � �. :;;, ., ' � � � {) u {) {) OrJ a� () Mokau 0 0 0 0 0 0 0 J;> or: � �.� � 0 0 0 � (I $ . R ,-,' 0 ,:, a a � () () () Line 8: 0 0 0 0 0 0 Waitara I i 39° o! � .,�. .,i 0 0" 0 � 0 0 u� Line 9: 0 Egmont

30'

Fig. 2: Sample positions.

37'

Depths in Fathoms

38°

};� Mt. Egmont 100

40° 13'

Fig. 3: Generalised bathymetric chart of the Western Shelf (contours at 10 fathom intervals).

JOO

40 JO 0 I 1�663

B665 1 I 1 100 B666

90 80 70 60 so 40 JO 20 10 0 0 I I I I I I I I I B661 V'l LINE7

I 11.11, ,, , Ill B657 I 100 B656

70 6 40 20 10 0 i° so J 9 I I I i° I I m LINE9 fs

:• I I 100 B655

100 90 80 70 0 so 40 J 20 ·O 0 I I I I I I i° I l I ,,,-r LINE 11 B651

;o B648

1 11 00 1 B645

Fig. 4: Transverse profiles across the Western Shelf drawn from echo soundings: depths are in fathoms.

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ . -, - _..- ft.) , Ltd ' " . ""' 700 .. . to .,,.,. . Aviation "' - ,- . rise " , L '" · Whites ' . - """' cliffs "" "' -··· - Photo: - -- - ound, "" ------, "l': . foregr .-. ,-., . ,-., ., , - immediate in coastline II Type I; Type (Coastal entrance. Harbour Kaipara to Muriwai from coastline western along north View 1. PLATE

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. . To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ e I inner portion. Conversely, in the southern region, weights on the upper portion of the jaws which had been fitted with several teeth approximately 3 in. long. the gradient is reduced seaward of the 50 fm line. c. The modifiedHayward orange-peel grab consists of four The shelf profiles along six lines, constructed close-fitting, sharp-pointed jaws, taking a roughly hemis pherical sample (of up to 1 ft 3 in volume) when closed. The from echo soundings, show these broad divisions in model used weighs approximately 100 lb, the maximum some detail (fig. 4). penetration being about 12 in. The grab has been modified to hang from a trip release which transfers the hauling wire The upper slope gradients in the central portion attachment to a closing mechanism when the grab enters the of the area are steep. Seaward of line 3 in latitude sediment. Sheet-metal plates have been added to close over the top of the sampler when the jaws shut and cut down 37 20' the depth increases from 88-227 fm in a loss of sediment as the grab is retrieved. distance of 3 miles; similarly off the end of line 6, A total of 261 stations was worked, grab samples being obtained at each one and cores (12 in. or over) at 46. Only in °l atitude 38 20' in a distance of approximately 7 the orange-peel grab was used for the stations from M.V. miles, the depth increases from85-500 fm. Ta ranui (table 1). Where coring was difficult, either because of the nature of the sediment, or through rough weather The Coastal ° Region: From numerous sources - making the gear too dangerous to handle, the corer was dispensed with and a grab sample only was taken. The photographs, maps, charts, and fieldobserv ations - grab provided a 13 oz oyster pot sample for grain-size a broad analysis has been made of the coastal types analysis and a 4 oz sample (alcohol preserved) formicro foundin the west coast region of the North Island. faunal investigations: the remainder of the sample being sieved for biological material. The configuration of the coastline varies con Ancillary sampling was carried out with a variety of siderably over the section under survey, falling into equipment that included Dietz grab, cone dredge, large orange-peel grab, and some bulk sediment samples obtained eight separate categories (fig. 5: Plates 1, 2, 3). in trawls were also available for examination. The mesh cone Three major rivers, Wanganui, Mokau, and dredge used consists of a 1 ft diameter cone with a rigid Waikato and four lesser but still substantial rivers, tubular galvanised mesh bag 3 ft long. It is an efficient sampler for benthic organisms. A small conical canvas bag Tongaporutu, Awakino, Waitara, and Patea, enter has been attached inside about half way along the length to the sea along this coastline. These rivers effect the obtain sediment samples. major drainage of the western half of the central

North Island. They traverse a wide variety of METHODS OF EXAMINATION AND ANALYSIS geological formations, but notably transport the A total of 289 surface sediment samples from the area products of erosion of Tertiary sedimentary rocks as well as 46 cores ranging from 12 in. to 36 in. in length and of poorly consolidated Quaternary volcanics was available in the Institute collections. from a large part of the area. Analyses of the majority of the surface and core samples for their content of ferruginous material have been carried out. Magnetic separations were made using a separator described previously : some of these results from selected METHODS OF COLLECTION near-shore stations were reported earlier (McDougall, 1961). The sampling gear used to obtain the majority of the Mechanical analyses of the "magnetic fractions" have also samples consisted of: been made in similar fashion to those of the total sample. Here the grain-size proportions in the "magnetic fraction" a. gravity corer. (mainly titanomagnetite) have been utilised to prepare b. N.Z.O.I.Modified Petersen grab. distribution charts. c. Medium-size Hayward orange-peel grab. A subsample of approximately 20 gms was set aside from a. The gravity corer head weighs about 60 lb and to this each surface sample for grain-size analysis, and was can be added, as desired, weights of approximately 30 lb treated in the following manner. each. The average total driving weight as used during this After being left overnight in a 0 · 03 % NaOH solution to survey was in the vicinity of 250 lb, but varied depending on assist dispersion, the resulting slurry was stirred gently to the nature of the sediment being cored. A valve fitted at the complete the breaking up of aggregations which had resisted top of the corer head prevents the core being washed out the action of the NaOH solution. Sandy samples presented during recovery. no difficulty at this stage whereas the muddy, silty samples The core barrel consisted of a 3 ft length of 1 ½ in. diameter required prolonged stirring. steampipe fitted with a plastic liner for easy removal of the When maximum dispersion had been obtained, the sample core. Occasionally the nature of the sediment permitted the was introduced into a nest of B.S. sieves, with mesh sizes use of a 6 ft barrel but, as sandy sediments were encountered of 8:16:30:60:120 and 240. at many stations, the 3 ft length was usually sufficient. The sample was sieved in the wet form, using a plastic The flexible-leaf core catcher was held in place at the wash-bottle together with a rubber spatula moved lightly bottom of the core barrel by the conical core cutter. The over the sieve mesh to keep the sample agitated. This was trip weight was so arranged as to allow the corer a "free most necessary in the case of the 120 and 240 mesh muddy fall'" varying from 10-20 ft before entering the bottom fractions. sediment (Plate 4). For the average sample approximately 500-600 c.c. of lo the initial sampling lines 1-8 (fig. I) the Petersen grab washing water was used. The weight of -240 fraction was "as used as a trip-weight : on lines 9-1 1 the orange-peel grab determined by taking a 25 c.c. pipette sample of this fraction, was used. The use of these large grabs as trip weights for the drying and weighing it, and then calculating the total weight gravity corer minimised station time and permitted a closer of the fraction. In the case of a large amount of solid material o,·er of stations than would otherwise have been possible settling out rapidly in the -240 fraction, the supernatant if the core and surface sediment samples had been secured liquid was decanted offinto a measuring cylinder, the solid Separately. The technique likewise made possible a survey residue being then dried and weighed, leaving the fine of the benthos, the grab providing a sufficient sample for a suspension to be treated by the pipette method. . reliminary study. The other fractions were left in the sieves and dried on a b. The Petersen grab used was a standard pattern sampling hot plate. The film of water in the wet sieve prevents some 0 · I m' of the bottom, modified by the addition of lead of the finer particles from passing through, so at this stage

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ Ltd. ion Aviat Whites Photo: beach. ironsand Note III.) Type (Coastal Harbour entrance. Manukau of south just om fr coastline n wester along south View 2. PLATE

Wide flat sandy beach backed by extensive low sand dunes

Narrow sandy beach. II 37° Cliffs u to 700 ft. hi h.

Narrow sandy beaches Ill backed by subdued low cliffs.

38°

Very narrow sandy beaches backed by cliffs V of variable height up to 800 ft. Some cut in raised coastal terraces with fossi I dunes. VI ° Cliffs as in V generally_ _ 39 >------<>- no beach.

Gravelly beach, Sandy in inlets, VII backed by cliffs (av. 100 ft.) with some fossil dunes and lahar flows.

Very narrow sandy beach VIII backed by cliffs up to 150 ft. high cut in coastal terraces with fossil and active dunes.

Fig. 5: Coastal types and major rivers, West Coast, North Island.

3. View north fr om Kawhia Harbour entrance. Mount Karioi (volcanic) in backgrnund. (Coastal Type IV.)

PLATE

light tapping of the sieves completed the sieving procedure. sieved and fractions weighed in the manner already des The individual fractions were then removed and weighed. cribed.The total weight of subsample averaged about 20 gms. No initial weight of sample was taken, the total weight being Analysis of the samples has thus taken the following arrived at by summation of the fractions. forms : Complete grain-size determinations have been The wet sieving method produces very clean, finely carried out on all the available bottom surface sediment separated fractions and was considered the most suitable samples out to 100 fm. In addition the percentage of titani owing to the large number of muddy samples to be processed. ferous ironsand in all these samples has been determined by The laboratory technique for analysing the cores was as magnetic separation. Two of the survey lines Piha 2 and follows : the surrounding plastic liner was cut longitudinally Egmont 9, situated near the northern and southern ex by drawing the core past two fixed opposing knives ; the core tremities of the area under consideration, were selected for was then halved longitudinally, one half being kept intact investigating the vertical sediment distribution. For all cores for further reference. from these lines, grain-size analysis was carried out as All the cores from lines 2 and 9 were analysed (a total of previously described. Visual examinations of cross sections 13). Subsamples 2 in. long were taken at intervals of 2 in. of all the remaining cores were made and recorded on along the length of the half cores. These were dispersed, wet sectional diagrams. 16

37'

..----.----.--- Granules and +8 � V. coarse sand +I 6 a Ix I �� sna�d :�� Fine and +/20 Y. fine sand +240

Mud -240

38'

39° NEW�L Y. MOUTH 4-� �;. �- ){< Mt EgmonL

40 ° s

Fig. 6: Areal distribution of groups of sediment grades on Western Shelf.

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ SYSTEM OF DATA PRESENTATION Median Diameters: For 46 surface samples from lines 1, 7, and 1 1 the median diameters have been Grain-size analyses of all surface sediment computed and their distribution along the sampling samples and of selected core samples have been lines with respect to depth and distance offshore presented in a number of ways: has been plotted (figs. 9, 10). Generalised Distributions of Sediment Grades: The Subsurfa ce Sediment Grade Distribution: Longi areal plot of distribution of groups of sediment tudinal sections of the superficial sediments along grades shown in fig. 6 is based on the occurrence lines 2 and 9 from core analysis are shown in at each station of grouped sediment fractions that fig. 14. The predominant sediment grade has been are 10% or more of the total sediment sample plotted against core depth. weight. For simplicity the fractions have been con sidered in four groups: granule gravel and very Subsu,fa ce Reflectors: A number of these are shown coarse sand: coarse and medium sand; fine and in cross sections of the western shelf illustrated in very fine sand; and mud. fig. 12. These sedimentary discontinuities were Thus on fig. 6 coarse and medium sand that in revealed by echo soundings from Traverse No. 172 one sample aggregated only 9% of sample weight by HMNZS Lach/an; they occur at depths of would not be shown. In the coarsest group, between several tens of feet. (Measurements from them mesh 5 and 8, much of the material was shell frag assume the same velocity of sound in them as in ments. Very few samples contained material larger sea water.) This forms the basic data for the than this. suggested Egmont Gulf (fig. 1 5). Grain-size Distributions along Sampling Lines: The Histograms of Grain-size Percentages in surface distribution of grain-size in surface sediments along sediments for lines 1, 7, and 1 1 are shown in fig. 1 1. each of the major sampling lines is shown in more Percentage weight is plotted against �ieve size, the detail in fig. 7. The percentage by weight of range being +8, +16, +30, +60, + 120, +240, each category of grain size has been plotted against -240 mesh. distance in miles offshore. For comparison a sketch profile of shelf contours is also given for Line 1, Muriwai: Well sorted, principally in the each line. very fine and fine sand grades, out to 40 fm. Line 7, Mokau: Anomalous coarse-grained sedi Distribution of Dominant Grades is shown: in fig. 8a ments sampled (Sta. C 357). of the total surface sediment; in fig. 8b of the Line 11, Wanganui: Predominantly poorly sorted "magnetic fraction". The figures used have been sediments. taken from the results of mechanical analyses of Also mapped were : the original sample (as in fig. 7) and of the "mag netic fraction" described earlier. Quartz Sands on the Western Shelf(fig. 13a). Only the dominant fraction has been plotted for Area of Prominent Occurrence of Dead Shell and each station. Shell Fragments (fig. 13b).

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ 0% � � 10 2s% 7S% so% 0% '.., '.., 1- o 0 0) 3 3 ""'-:J - "' 0 IO 1 I 319 "'": (C """ ES LES IL N.M N.MI WAIKATO I 20 20 20 3 E LIN "�' 1' I 30 30 30 nes. li Im Im 0 0 +8 +8 40 12 +16 +3 +60 -2 + +240 ) MILES MILES � � sampling (g) (g) (cs) (vcs) (m) (fs) (ms (vfs) 00% 1 7S% so% 2s% 0% oo NE 0 o o N. :l along () Z ::I FINE ' : · ? frags.) ) vfs · 18 .) ·: · VERY LEGEND 9-3 Shell III�::: sand frags _zt1 30 distribution sand 10 10 sand 10 (C LES sand (incl. (incl. Shell coarse fine SAND sand ium ZONE N.MI L n-size �: PIHA Gravel Very (incl. Med Coarse Mud Very Fine FINE Grai :I . ,d!1Tilll11111tbf1111/ :: E 2 7: - D mllIIIII � [: = [] LIN �-� �T 20 20 20 Fig. ES � Ml-L 00% 2s% 1 0% 7S% so% 00 N. '. 0 o (C295-305) MILES 10 10 N. MURIWAI FINE I ZONE NE LI k?='l VERY SAND N 0

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This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.

To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ m m � 5% 00% 1 75% 2 0% so% 0 � '0 o I I o 0 I co 0 w z � I 0 V) w _, " L < z 0 111111111ifilJJIII 11 11 11 IIII IIII ; 10 : 10 111pHu+w::::- 1111 I 11111 l 11111 I 1111 111Tlllllllll 111Tlllllllll 1 ZONE , , -- lines-continued ;" ;" - 20 20 ) 7 3 11111111 11111111 4 33- 111111 4 11 sampling 111 FINE SAND FINE (C (C454-462) 111 111 11 RA along ; ; Jc 30 11 11111 WE 11 ILES HA Legend MILES N.M 10 11111111111' 11111111111' N. distribution 11 for E 11 "' "' : 20 40 40 LIN p. "'"' "' "'"' See Grain-size 11111111 11111111 7: 11 Fig. m ZONE 111111111 o : s so MUD 11111111111 11 1111111111 11 11 : 60 60 ;, � I'--) 0\

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. . To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ e I I � % 0% o 0 25% 0% 10 75% s 10 ° o 0 •-1 •-1 10 I 10 111I111111111111111111111 111I111111111111111111111 11 11111111111I111111 11 1 20 20 lines-continued 0 0 f 3 3 sampling S S (C453-438) ILE along ILE M llihiilllllilllnllllllllllllllllllllllllim M N. N. CS 1 -40 40 Legend distribution for .... WANGANUI ...... 20 . II ······ · . - . p. 1111111111111111111111I111111111 1111111111111111111111I111111111 ...... - . 11 · NE ...... · ...... · 1111 LI ...... See Grain-size · o 11 . I ...... 50 s ...... ·: ...... 7: . 1111 · .... . · 111 . 1 1 ...... ············ ·: ...... Fig...... ················ ...... ·: ··· ...... · ...... · 11111111111 1 ...... 11111111 ...... : 60 ·········· 60 ...... ······························ 11111 ...... ::::::.:.:..n,;.;, 1 11111 · . : ...... · ...... · . ·: ...... ····················· ...... 1111111111111 ...... ·: ············· ··········· ...... 0 0 I 7 7 �

The major constituents in the sediment are mud, The zone between 0 and 56 fm (0-13 miles) can be very fin e sand and fine sand. These three together distinguished as a fine sand zone: the outer shelf predominate over the greater part of the shelf, but can be designated a very fine sand zone. particularly in the area north and west of Cape Mokau (line 7): Here the zones are less clearly Egmont. Immediately south of Cape Egmont there defined, the sediments not being as well sorted. is a more complex diversity of sediments. A small very fine sand zone exists from the shore The areal plot of sediment grades that occur in out to about 5 miles (23 fm) averaging nearly 70% proportions of 10% and over (fig. 6) allows con very fine sand. Mud and fine sand average about sideration of the major aspects of distribution. In 10 % and 4 % respectively, the coarser fractions particular it highlights the anomalous occurrences being negligible. From 5-30 miles offshore there is of the finer and coarser sediment grades. However, a fine sand zone, with nearly 70% fine sand, 10% the nature of the pattern of distribution of the very fin e sand, 7% mud, and 12% medium sand. dominant sediments is more precisely shown in The coarser fractions over this area average less considering the variation in sediment distribution than 1 %. The mud fraction reaches its maximum along each of the sampling lines (figs. 7, 8a). percentage of 61, 5½ miles from shore in 23 fm . Lines 1, 7, and 11 are here described in detail to There is a sudden change in these circumstances match the additional information given on median however about 30 miles (52 fm) offshore, where a diameters given in figs. 9 and 10. decrease in the fin er fractions occurs with very fine sand and mud becoming negligible. Fine sand also GRAIN-SIZE DISTRIBUTIONS ALONG SAMPLING LINES shows a marked decrease, but in this one area on 1, 7, AND 11.* (See also figs. 9, 11). line 7 the coarser fractions-coarse sand and very coarse sand-increase to 35 % and 33 % respectively Muriwai (line 1): From the shoreline to 50 fm, with gravel 7%. Between 30 and 90 miles offshore 12 miles offshore, there is predominantly fine sand, (52-80 fm), the coarse fractions, medium sand, about 12 % very fine sand, very little mud, and an coarse sand, very coarse sand, and gravel almost average of 10% of medium to very coarse sand. disappear leaving mud, very fine sand, and fine sand In the next zone offshore, the proportion of mud with averages of 38%, 27%, and 32%. (20%) and very fine �and (40%) are greater; fine From 90 miles offshore to the shelf edge, mud sand is much reduced (20 %) and the medium to (38% at 95 miles) and very fine sand (60%) are the coarse sand grades negligible. only two significant constituents of the sediment. The percentage of mud is negligible from shore to 10 miles offshore (40 fm). Here an abrupt in Wanganui (line Jl): The sediments are poorly crease takes place to a maximum of 25 %, 15 miles sorted over the length of this sampling line (fig. 11). offshore (70 fm). Mud occurs in three separate areas with the per The percentage of very fine sand fluctuates centage increasing from shoreline to shelf edge. between 5 and 30 out to 56 fm; coinciding with an The maximum percentages for these areas occur at increase in the percentage of mud, it also increases 3, 20, and 58 miles from shore with 11 %, 14 %, and to a maximum of 75% at 15 miles offshore in 25 % respectively. Between them, from 8 miles to 70 fm. 18 miles, and at 38 miles, mud is in negligible The percentage of fine sand rises from the near quantities. Very fine sand follows much the same shore figure of 66 to a maximum of 80 (4 miles off pattern with maximum percentages at 3, 20, and 47 shore in 22 fm), then decreases a little to 12 miles miles from shore, the amounts being 32%, 10%, offshore, then rapidly to a minimum of 7 %, 15 and 10%. miles offshore in 70 fm. Fine sand reaches a maximum of 78% 12 miles The coarser grades present (medium, coarse, and offshore, fluctuates to 2 % at 38 miles, then very coarse sand) broadly decrease in abundance averages 20% out to the end of the line (68 miles seaward but nowhere exceed 20% of the total and 46 fm). There is an average of 23 % of medium sediment. sand for the whole line, reaching a maximum of The maximum of mud (at 14 miles and 75 fm) 77% 14 miles offshore and a minimum of 6% 3 occurs slightly shoreward of the maximum of very miles offshore. fine sand and the minimum of fine sand. Coarse sand, very coarse sand, and gravel follow much the same pattern, there being three areas where these coarser fractions are concentrated. At *For similar description along all other sampling lines see Appendix. 5 miles offshore in 15 fm, coarse sand rises rapidly

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ to 18 %, then falls away equally rapidly, rising again sediment grade is demonstrated whether the sedi at 16 miles to 31 % ; a slight decrease then a steady ment is dominant or not: as well, the minor occur increase to a maximum percentage for the line of32, rences of less significant component grades can be this being reached 38 miles offshore in 23 fm then assessed. In the preceding section the zones there falling away graduall y. Very coarse sand likewise defined are based on the sediment grade dominant at 4½-5 miles offshore increases from nothing to in each sample. The zones are not of the same 14%, at 16 miles shows no increase, but reaches a significance nor based on the same characteristics maximum of 35 % 30 miles offshore in 30 fm; from as the "belts" defined in the consideration of dis 1here gradually decreasing towards the shelf edge. tribution of individual grade components that Gravel at 5 miles (15 fm) is at its maximum of follows. 15 %- This falls away rapidly until roughly 20 miles offshore (27 fm) from which position to the end of Mud: Mud is present over a large area of the shelf. the line the average percentage is 9. From the northern extremities of the survey, just south of Kaipara Harbour, mud is present from ZO:--IATION : roughly the 50 fm line to the shelf edge. This con dition persists southward to an area north-west of From the zonation that occurs along individual New Plymouth where mud is present very nearly - mpling lines it is possible to recognise a clear to the shoreline. pattern of zonation of the shelf sediments as From this position there is a narrow area extend ·haracterised by the dominant grade (fig. 8a). ing north to the Waikato River mouth in which The major divisions into which the surface mud is present from the shore to an average -� iments of the shelf can be classified are: distance of 7 miles offshore (25 fm). Around Cape Inner Very Fine Sand. Egmont there is a strip from the shore to an average Fine Sand. of 4 miles offshore in which mud is not apparent. Outer Very Fine Sand. South of Cape Egmont mud first appears at 30 Mud. to 40 miles offshore except for a small mud area o In a narrow inshore zone that extends to an ff the mouth of the Wanganui River. These d .c\ erage depth of 25 fm sediments with a dominant istributions outline the Inner Low-Mud Belt (in rcentage of very fine sand are found. This Inner the Taranaki Bight south of Egmont) and an Outer I ·err Fine Sand Zone extends from Piha to Waitara. Low-Mud Belt (from Kaipara to Mokau). .-\djoining this zone offshore is a zone in which The shelf area where mud is the only component :�diments with a dominant percentage of fine sand present averages 15 miles in width, sweeps in from ur. This Fine Sand Zone is continuous from the shelf edge south-west of Egmont, extends in a n _ Iuriwai to Waitara and its seaward boundary is orth-easterly direction towards Egmont, then veer i an average depth of 50 fm. s away to the west and terminates about 45 miles west of Egmont. There is an average of 98- Further seaward is a zone of sediments with a 99 % mud in this area (the Central Mud Belt). iominant percentage of very fine sand. This Outer ·err Fine Sand Zone extends from Muriwai to Very Fine Sand and Fine Sand: The fine and very . Iokau at depths from 50 fm to the shelf edge. fine sands are present over a greater area than the These zones all lie north of Cape Egmont. South mud component, and the combination is found o - the Cape the inshore sediments are variable, over the entire shelf except for the area of mud just u1 offshore is a large area of sediment in which the described and an area roughly 25 miles west of the ominant percentage is mud. The Mud Zone extends Mokau River. From Cape Egmont to the Mokau sou1h and west from depths of about 40 fm in the River, coarse and medium sand are absent from i inity of Cape Egmont. the Inner Low-Mud Belt. Coarse and Medium Sand: These coarser com .-\REAL DISTRIBUTION OF INDIVIDUAL GRADE ponents are found in an elongated area extending (m!PONENTS from the northern to the southern limits of the The distribution of the individual grade com survey. Between Kaipara Harbour and Cape onents has been shown by means of an areal plot Egmont it varies approximately in width from 4-25 ( g. 6). As has been already mentioned, all the miles. South of Cape Egmont, from a narrow zone omponents shown are 10 % or more of the total 4 miles wide, it broadens to 70 miles in width in the weight of sediment sampled. region of Wanganui. The Coarse Sand Belt co Though this method of presentation ignores all incides approximately in the north with the Outer ·he minor occurrences yet it is useful in two Low-Mud Belt around 50 fm, and in the south respects. The total distribution of a particular with the Inner Low-Mud Belt.

•.• .. •• Granules (including shell +8 fragments) ;:t\tJ,ff Very coarse sand +16

° 37 [2[TI Coarse sand a Medium sand +60 - Fine sand +120

- Very fine sand +240

� Mud -240

* Mt. Egmont

40° s

Fig. 8: (a) Distribution of dominant grades in total sediment. 30

• Fine sand + 120

lli.lill� Ver y f i n e sand +240

E=3� Mud -240

° 3 8

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ A variation in the composition of sand grains is has not been evident elsewhere on the shelf under evident where a distinct area of golden-grey grains survey. The sediment is similar to that in the extends from just south of the Manukau Harbour golden-grey sand but the quartz grains are stained parallel to the coast and terminates south of the a deep red brown. These two areas of quartz sands Mokau River (fig. 13a). The sand adjacent to the lie at depths between 20 and 50 fm. border of this area is principally fine grey sand, of Over roughly the same area as that just des varied composition. The sediment in the golden cribed quantities of large Foraminifera are also grey sand areas is dominantly composed of well evident in the sediment samples in sufficient rounded quartz grains, some stained yellow. amount to enable a shipboard distinction between A small isolated area in which reddish-brown these samples and others to be made. The area is sand occurs is situated offshore from Raglan. This narrow to the north and at greater depth.

LINE 7 0·8

0·6 M.D. (mm) 0-4

0-2 1---L__- __j______j_ ___ -'----'------'------'----.J....._----'------'---- -:,;1- o 1I rn1T11r111 fffTfTJTTTTlllTn1 mmJTiTTT[iTiTI[ll1111l 50 Shelf edge ----rnTTT1TfT1m _ flT[1lll'''"""' J1J11Tf1TITI1111111 1 1,, ,,1,,,,,,111111 11111111,111111111111111111111111 111111,,mmnmmnrrrnmmnmnmmrn FATHS 100

100 90 80 70 60 50 40 30 20 10 N. MILES

LINE II 0·8 LINE I 0·8

0·6 0·6 M.D. (mm) 0-4 0-4

0·2 0·2

N\0 0

50 Shelf edg 50 r FATHS 100 I roo

70 60 50 40 30 20 10 20 10 N. MILES N. MILES

Fig. 9: Median diameters of surface sediments along three sampling lines ; 1, 7, 11.

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ On several areas of the shelf, shells and shell Close inshore around Mt. Egmont the granule fragments form a significant proportion of the grade includes rounded gravel and small blocks and sediment (fig. 13b). boulders of volcanic rocks which have been Granules (including shell f agments): North of sampled up to 5 miles offshore. Further south in Egmont this component appears in three small iso this Belt the boulders tend to disappear, the surface lated areas Gl (60 miles offshore), G2 (44), and sediment consisting dominantly of coarse shell r G3 (20), (fig. 6). The outermost two areas lie at the fragments and gravel. shelf edge: G3 is in 50-60 fm. South of Egmont off the Patea coast lies the extensive Granule Belt \\ hich occupies the same area of shelf as the coarse and medium sand. MEDIAN DIAMETERS Each of the small areas shows variation in the type of sediment found. G2 contained pieces of Median diameter values for the surface sedi c"ncrusted well bored fine-grained ledge rock ments, obtained from lines ( 1, 7 and 11) show that ( 8666). South-west of this is an area where numer diameters of less than 0·25 mm are predominantly ous large shell fragments abound. G I has sediment at I 0-40 fm and less than 25 miles offshore, ranging from pebbly coarse black sand at its though they are also found at 70-90 fm. Median northern end to muddy finesand with coarse shell diameters greater than 0·40 mm are found at depths fragments and numerous rounded andesite pebbles not greater than 30 fm nor more than 40 miles off t 8797) up to 3 in. long. shore (fig. 10).

0 0 ' / ' • • /$ I e I 10 I • ' 10 I (j)� \ X • • •• • • \ X t \I 20 I >!' x • • \ 20 ,.\�� ex I \ X • ' 4>/ (j) ...._ ...... 30 \ • 30 • \ 1 I " xl w ' / a: • 40 ..... _,,,.. 40 4> � 0 50 u._ 50 = 0u._ X w • 60 I:....I 60 4> z • 70 70 4> / -- .... /--� ,I 80 I \ ' 4> I ,..I 90 ,1 90 4>

1 00 100 0·10 0·20 0·30 0·40 0·50 0·60 0·70 0·10 0-20 0-30 0-40 0-50 0-60 0·70 MEDIAN DIAMETER MEDIAN DIAMETER

X LINE I 11 Observations LINE 7 19 Observations e LINE 11 ! 6 Observations

F:�. I O: Distribution of median diameters with depth and distance along lines. As line 11 is oblique to the shoreline a greater scatter of observations is present.

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ T T WES WES �� •60 +6Q C4JS 1 1 Cl05 CJ64 0 ·30 -1 •3Q 1 1 , 6, 1 ,11 •16 , · I 1 . •P, ·s +8 j J - j . O O 10 0 80 u, J · 61) cc. "' 20 6 100 40 1 240 sediments 1 4Q •2 1 the � '""' •12Q of • • •. •. "' 1 . CJ03 +60 · F:1� �� CJSS C441 , O •J •10 I � 1 sorting 6 ' · .16 •16 I +_lQ I in I I 1 :3 · · ,3 •8 , ] and i - J -j -j ] J o 0 0 > n 60 7 20 6U 100 80 80 /0 60 40 100 1 ' 0 grade 21 . 1 in 10 ·! 302 " = = C CJ57 C442 variations -- - �. . E � � � SIZ , showing � SIZE SIZE � � ] �� - ] ] J 0 0 0 so 60 <0 2 2 80 60 100 80 60 20 OO 40 I 100 11, EVE 240 and SIEVE SI SIEVE 7, • l, •l)Q +f'1Q I es 6 . JOO •6() 44 = = C lin . C)SO -� �� I C +JQ for � -1§:� 1, •16 - ---,. s,, +8 L 1, J -, ...j J 0 0 O 60 ao 20 20 , 20 1, 00 60 10 100 so O 40 I 100 percentages j 240 }4Q . � 40 4Q' ·7 '+2 •1)0 •12Q 1 grain-size •60 •60 C297 of CJ48 1 C451 30� �30 +JQ 1, +16 ,16 •16 J I 31 •8 . +g stograms L_--�- � 1 j � � Hi o O O 0 o cO 10 ,0 J "l 60 40 /0 so 60 100 • 100 100 1 11: Fig. •2·,0'-240 I � 8 � 1 0 ST ST } 1 • � I 1 EA EA EAST 53 ,o� •6Q C295 �no C4 1 �� ', II Q 7 +30 •) 1 l•10 �-== �-== •16 •16 •16 1 LINE LINE LINE 8' -- ·8 +8 , , .j · l - .. ] ---, ...j l - 0 0 0 e 80 60 !O < 2 2 (, so 60 20 40 80 100 100 � 100 % % %

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ m m DISTRIBUTION OF DOMINANT FRACTIONS OF THE a narrow area of mud, then by very fine sand over TOTAL SEDIMENT AND OF T!TANOMAGNETITE most of the shelf, broken by elongate patches of dominant fine sand. Near the shelf edge the A comparison has been made between the distri titanomagnetite dominant is mud. bution of the dominant fractions of the total sedi South and west of Egmont the distribution is ment and the "magnetic fraction" (fig. 8). poorly documented and the dominant grade varies from medium sand to mud. Along the Egmont Titanomagnetite occurs in the total sediment sampling line the proportions of titanomagnetite in only in small proportions (ranging from 0·3 to the samples were so small that insufficientmaterial 36 %), however the average proportion is 2 · l % was available for mechanical analysis. (McDougall, 1961). The distribution of total sedi ment has been described earlier. The distribution Comparison of Distribution: Where the dominant of titanomagnetite fol lows a broadly similar pattern grade in titanomagnetite fractions is mud along the for the area north of Cape Egmont. Here the dis shelf margin the dominant grade in total sediment tributions of different dominant grades are aligned �arnples is the same except for six stations where parallel to the shore and shelf edge as are the total this grade is slightly coarser or slightly finer. In the sediment dominant grade zones. A narrow area of area south of Cape Egmont the total �ediment is very fine sand near shore is succeeded seaward by coarser, being medium and fine sand.

Fig. 12: Profilesof subsurface reflectors. Echogram along traverse shown in (a) below.

w E 0 60

L65 0 0 � 7 <

LL 75

(a) Offshore from 39° 13' S. 173° 42 · 5' E bearing 284.

w E

0 40

VlL6 0 0 I

(b) Offshore from 39° 18· 5' S. 173° 41' E bearing 270.

'.F

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ For the narrow area of titanomagnetite mud grade just offshore between Waitara and Marokopa the dominant grade is the same for the total�c-- sedi ment. North of this, to the Waikato River mouth - - the titanomagnetite mud area lies in,- the Inner Very Fine Sand Zone of the total sedi.,..-,ment. Where the r- dominant grade of titanomagnetite- is very fine sand the dominant grade of total sediment is typically -.-- fine sand,- - particularly for the shelf north-- of Cape Egrnont. Conversely, however, where the dominant-, --. - - grade of total sedi----,-ment is mud, in the offshore area south and west of Cape Egmont the dominant grade in the- titanomagnetite is for the most part coarser,- being mainly very fine sand.

r-° ° ° ° 173 30' E 174 175 37

I I I I I

\ EI] Golden-grey \ quartz sands. � Reddish-brown quartz s:mds.

/ I / I

/ / / /

Mokm, R.

I I

/ / I / I / I I )IE Mt. Egmont Fig. 13 : (a) Areas of quartz sands on the Western Shelf.

Fig 12: (c) Echogram along traverse shown in fig. 2(a).I

37°

38°

I I \ I 39° \ - - _, ' ' I

I I I

I 00 fath. \\

40° s

Fig. 13: (b) Area of prominent occurrence of dead shell and shell fragments.

DISTRTBUTlON OF SEDIMENTS IN CORES with numerous fine shell fragments. The remainder of the core (20 in.) is evenly distributed muddy (fine- very The distribution of the subsurface sediments is fine) sand with an average of 28 % mud and 67 % of the fine- very finesand component. There are fewer shell shown by means of two sectional diagrams (fig. 1 4) fragments in this lower section. of lines 2 (Piha) and 9 (Egmont). Core C 312 (8 miles offshore in 30 fm) is of a similar pattern but with more fine shell fragments throughout Piha (Line 2): From shoreline to the shelf edge, a distance of its length of 12 in. The top 3 in. consists of unconsolidated 20 miles, .lO stations were occupied, five of which produced fine sand with numerous fine shell fragments, and the cores averaging I 6 in. in length. The distribution of surface remaining 9 in. of the core are coarser in grade than the sediments over this distance is principaily fine and very fine previous core. To a depth of 6 in. some of the shells sand out to 50 fm. At this point mud makes itself apparent and shell fragments are noticeably coarse. to a marked degree and continues to the sl1elf edge as the Core C 313 (19 in. long, 10 miles offshore in 37 fm), major constituent of the sediment. consists of evenly distributed muddy fine sand with Core C 31 l (6 miles offshore in a depth of 23 fm). The small shells and shell fragments, a slightly greater per top 1 in. consists of unconsolidated muddy fine sand cemagc of these being in the top 1 in. and lower 6 in.

PIHA (Line 2)

N.Z.0.1. STAT10N No. C31 S C3 !4 C3 13 C3 12 C3 il " "' CORE LENGTH 20" 1 4 19" 12" 2(} .S:

....

C: C �; '.�;d�) -;:� ��: :��:��(��· �� ,�-j;_f;_-�----,--_·.,----,-_jt:ij " , :- I j I i 1--,-----i-- ! 1 V, 20 15 10 MILES (a) Unconsolidated finesand with shell fragments. [J] ( b) Muddy fine-ve;·y fi ne sand. � (c) Fine-very fi ne sandy mud. EJ (d) Muddy ftnesand with shell fragments. S

EG:'-":ONT(Line 9)

t! .Z.0.1. STATION No. C432 C-1l i C430 BJ 17 C429 C428 C427 C424 C422 CORE LENGTH 22" 12' 14' 6" ,,,.. 30" 26' 23" 22' 3

(b) Muddy fine-very fine sand. � (c) Fine-very fi ne sandy mud. CS) (d) Muddy fi ne sand with shell fragments. E3 (e) Mud. E3 Fig. 14: Cross sections of sediment beds along two sampling lines.

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ Throughout the total length of the core there is an bottom 2-3 in. of the core, however, there is a marked average of 60 % fine sand- very finesand and 25 % mud. increase in the quantity of shell fragments although Core C 314 (14 in. long, 12 miles ofTshore in 43 fm). there are more of the larger sizes seen in the previous The core consists of evenly distributed muddy fine sand core. In this section there is 33 % mud, 50 % very fine with small shells and shell fragments. There is an average sand - fine sand, and 11 % shell fragments of granule of 73 ½ of the fine sand - very fine sand component and size. 20 % mud. Core C 431 (50 miles offshore in 74 frn, 14 in. long). Core C 315 (20 in. long, 14 miles offshore in 54 fm). The upper 10 in. is a very even consistency of muddy This core is well graded, being muddier in the top 6 in. fine sand with an average of 42 % mud and 56 ½ very than the previous cores, and becoming coarser through fine sand- fine sand. Shell fragments are not apparent out its length. The top 2 in. is finesandy mud with 59 % in this section but are present to a small degree in the mud, 35 % fine sand - very fine sand and 5 % of coarser bottom part of the core. Here the mud decreases to 30 % material. At the bottom of the core these percentages with an increase in the verv fine sand - fine sand con1- have become 15 and 59 respectively and 26 % of coarser ponent to 65 %. There is a noticeable amount of frne material principally made up of shells and shell frag shell fragments which comprises the remaining 5 ½. ments. Core C 432 (60 miles offshore in 98 fm, 22 in. Jong). There is a very consistent appearance over the total The individual cores obtained along line 2 length of this core. Percentages show a slight decrease demonstrate in fig. 14 (a) : in the mud fraction from 46 to 30, and an increase in the very fine sand - fine sand component from 52 to 70. r (1) out to 30 fm (8½ miles offshore) there is a The remaining f actions arc negligible throughout. surface unconsolidated layer of fine sand with a maximum thickness of 3 in. - layer (a); The picture shown in fig. 14 (b) of the subsurface sediment distribution from the shore to the edge of (2) this overlies a lens of light grey muddy finesan d the shelf along line 9 is of a layer of mud and muddy with numerous fine sand grade shel l fragments sand averaging 2-3 ft in thickness, overlying a layer which decrease in number progressively down the with she][ material of varying degrees of coarseness. core to an average of 14 in. - layer (b); From the shore to about 20 miles offshore the (3) a third layer which contains fewer shell frag mud layer consists of light grey mud averaging 97 % ments but in which the sand grade has become mud, with no shell material at all, layer (e). coarser - layer ( d); Between 20 miles and the shelf edge there is a marked increase in the very fine sand - fine sand (4) from 12 miles offshore in 45 fm , a muddy layer component making the pure mud into muddy fine becomes apparent, overlying the previously men sand, layers (c) and (b).The general tendency is for tioned layers. Coarse sand grade shell fragments a muddier sediment at the surface becoming less appear in this region and increase towards the muddy and more sandy down the core. bottom of the core - layer (c ). The shelly layer is apparent from 30-50 miles, Eg mont (Line 9). From the shoreline to the shelf edge, a l ayer (d). Cores inshore of this zone did not sample distance of 60 miles, 17 stations were occupied, eight of which the shelly layer (fig. 14b). produced cores averaging 23 in. in length, with the longest core being 36 in. Surface sediment distribution has been discussed earlier; between 20 and 68 fm (the Central Mud Belt) the surface sediment is principally mud: from this depth to the shelf edge the mud and very finesand - finesand SUBSURFACE REFLECTING HORIZONS component averages 61 ½ and 37 % respectively. Core C 422 (9 miles offshorein 60 fm). Throughout its [n the area immediately to the west of Cape length of 36 in. there is a consistent average of mud Egmont, echo soundings have recorded a sub 95 %, and very finesand - tine sand 4 %. stantial subsurface feature (figs. 12a, b). Two east Cores C 424, 427, and 428 are similar in composition to core C 422 with a slight increase in the mud percentage west traverses 5 miles apart show a depression in from 95 to 98. They were taken in 61 , 62, and 66 fm the sediment surface. On the northern traverse being 22, 23, and 26 in. long respectively. (fig. 12a), this first shows at a depth of 60 fm and Core C 429 (30 miles offshore in 68 fm and 30 in. long). This core shows a different consistency from the pre terminates 11miles seaward in a slight rise in 68 fm. vious cores of the line. The percentage of mud de On the southern traverse (fig. 12b ), the depression creases from 86 at the surfaceto 30 at the bottom of the commences about 9 miles offshore in a depth of core. There is a marked increase in coarser material in the top 24 in. as shell fragments up to 1 in. diameter. 50 fm and extends 11 miles seaward terminating in At this stage there is 30 ½ mud, 3 7 % very fine sand - fine 69 fm . sand, 6 % coarse - medium sand and 26 % she! I frag ments of granule size. The general appearance of the Underlying this depression in the sediment sur core remains the same from this area to the bottom, face (fig. 12b) are reflectingh orizons, the most sub with the numbers of very coarse shell fragments varying stantial appearing to be a continuation of the ex slightly, upsetting the percentages in a marked fashion as they vary. posed sea floor surface at the east and west Core C 430 (40 miles offshore in 71 fm, 1 2 in. long). boundaries of the feature. This interface lies at a Jn this core the upper 8-9 in. consist of sandy mud with depth of about 50 ft below the sediment surface. an average of 60 % mud and 37 % very fine sand - fine sand. There is a gradually increasing but small per Two other interfaces appear at 30-40 ft below the centage of fine shell fragments down the core. In the sediment surface.

Three factors control the sediment distributions the coarse sands of the Coarse Sand Belt remain in that can be seen at the present time. substantial proportions in the surface sediment. (1) Nature of the sediment in specific localities In view of the heterogeneous assemblage of under earlier regimes. volcanic and sed imentary rocks forming the present hinterland of the North Island west coast, it is not (2) Availability of present-day sediments. easy to see that local differences in the resulting (3) Present-day water turbulence and velocities. present-day sediments could be a dominant factor Undoubtedly all the near shore sedimentary in controlling grain size distribution. facies exist or persist under the direct effects of the Mid-Shelf: The coarse sediments in the mid-shelf present physical environment. Along and near the region north of Egmont (the quartz sands of the shoreline the maximum wave effects are exerted Coarse Sand Zone) are more probably associated and though, as Pan tin ( 1964) has pointed out, with water velocities of an earlier wave zone rather oceanic and tidal currents may have maxima that than with the smaller current velocities expectable lie offshore, yet there is no external evidence of in the present depths (25-50 fm) over this area, this in the area here considered. If decreasing though as suggested these may be sufficient to turbulence because of decreasing wave effect with prevent mud deposition. This implies a former increasing depth be assumed, this then implies the near shore (0-5 fm) environment in which the existence of the classic seaward distribution of: quartz sands were deposited. The zone terminates (1) Inshore mud deposited by flocculation at at Cape Egmont. If sea level were then at the river mouths; - 50 fm mark then at this Mid-Shelf time, the (2) Near shore zone of sands; coastal outline would have continued south westward toward the South Island and Cook (3) Zone of finer sands and muds. Strait would not have been open.

NORTH OF CAPE EGMONT Outer Shelf: The shelf deeper than 50 fm is covered with sediments in which very fine sand grade is Inner Shelf: Zonation of dominant sediment grades dominant and at its outer margin by mud. The on the shelf is clear and for the area north of Cape clear boundaries to the sediment zones and their Egmont follows a regular pattern. The succession association with particular depths both suggest that of dominant grades seaward - very fine sand ; fine over all of this northern shelf these sedimentsare sand ; very fine sand - does not follow the distri largely relict and owe their existence to sedimentary bution model: the coarser of these grades dominates processes developed at lower stands of sea level. in an Inner Shelf Zone between 25 and 50 fm. This It is of course possible that the distribution of coarsening of grade seaward as indicated by the water velocities on the shelf is zoned, in a similar dominant grade is matched by the occurrence of manner to the sediments, but as stated earlier there coarse sand near the mid-shelf. is no external evidence that this is the case. Thus on the Inner Shelf one or other of these circumstances is dominant. SOUTH OF CAPE EGMONT (1) The distribution of water turbulence and On this part of the shelf sediments with mud as velocity is anomalous; the dominant grade are widespread. With these (2) Pre-existing sediments have not yet been grouped as the mud zone there is Jjttle other evi buried by present-day deposits; or dence of zonation. It is made clear by the occur rence of mud in depths of 40-70 fm (but beginning (3) Basically different sediments are being sup close inshore near Cape Egmont) that this is the plied to different portions of the Inner Shelf. normal sediment appropriate to these depths on It is obvious that there are no critical external this part of the shelf. criteria for establishing the degree to which each of The supply of sediment from shoreline and rivers these circumstances prevails. If the current regime may well be such that the present day "normal" is markedly variable over the shelf then the velocity sediment for the whole of the shelf area other than over the Fine Sand Zone and Coarse Sand Belt is the near shore zone may be mud. The amount de higher than that inshore and offshore from this posited from place to place varies from nil to sub inner and mid-shelf area. The deposition of mud, stantial enough quantities to make it the dominant which as suggested above is there available as a grade. It is not possible to distinguish present day present-day sediment, would thus be prevented and from relict mudif such occurs.

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ There are few data that help to explain the sub in Post Shelf Edge time. in both these times the stantial difference between the shelf sediments mud may in fact be derived from the sedimentary north of Cape Egmont and in the mud zone. The materials produced on the west coast of the South area of dominant mud south and west of Cape Island that are carried northward by coastal Egmont lies mostly seaward of the 40-50 fm line. currents (Brodie, 1960) and deposited where these For comparable depths on the northern part of the currents slacken over the wider extent of shelf in shelf, the mud percentage is mostly low. This im plies either that there is a lesser amount of mud the western entrance to Cook Strait. available here for deposition, or that the water To summarise, present-day sediments are prob velocities are high enough to prevent substantial ably confined principally to the mud and very fine deposition of the mud fraction, or that the mud sand grades. Except for the near shore zone the of the mud zone is partly relict. If a significant part areas with dominant grades coarser than mud are of this mud is relict then the difference between the probably areas of relict sediments from earlier two parts of the shelf that exists now also existed sedimentary environments.

PHASES OF SEDIMENTATION

The morphological divisions into which the shelf grade could similarly have been deposited in the south of Cape Egmont falls can be taken as indi Cape Egmont "depression". Then compaction un cative of at least two major time intervals. It is conformities would have occurred if, in intervening reasonable to suppose that the processes of erosion periods of lower sea level, the upper less-compacted and sedimentation that shaped the near-horizontal portions of the previously deposited sediment were but irregularly surfaced outer shelf - stretching stirred up by increased wave and current activity from the gradient discontinuity in 50-60 fm to the and transported elsewhere. shelf edge - were distinct from those that followed If sea level were radically lowered then near shore and controlled the shaping of the inner shelf from wave and current processes could bring about the �O fm to the shore. Correlation with the mid-shelf deposition of coarser grades. The coarser sediments ( 40 fm) discontinuity in gradient in the northern that are at the surface just landward of the eastern area considered here is probable but by no means boundary of the "depression", and the slightly clear. coarser grades west of this area suggest that the For the southern area it is helpful to recognise interfaces may be composed of similar materials. two time intervals-Post Shelf Edge, and Post Consideration of the relative stratigraphic posi \1id-Shelf. The inner margin of the Cape Egmont tions of these horizons is complicated by two subbottom reflectors coincides with the seaward factors. One is the proximity of the depression in boundaries of granule areas in the Coarse Sand which they lie to the Cape Egmont volcanic com Belt and of the Outer Low-Mud Belt. The area in plex, and its associated fault features. It is at least which the reflectors lie has a possible north-south possible that the depressed area is the superficial seaward boundary and lies in the Central Mud indication of a small graben-like structure. Belt. Judged by this example and the less deeply Secondly, while the depression may be a function buried reflectors to the south (Echo Sounding of erosion and deposition the area may have traverse No. 422), the uppermost sediment is filling suffered from warping and relative vertical move depressions in a pre-existing shelf surface that else ments. (Superficia1ly, the surfaces could have under \1·here coincides with the present upper surface of gone tilting with a seaward component.) However, the sediments. On this basis the present-day sedi no quantitative estimate can be made of the effects ment in the area off Cape Egmont is mud. of these events if in factthey did occur. The lowest The sedimentary interfaces(f g. 12) may be major reflector is at present between 72 and 80 fm (av. 76) grade changes (e.g., they may be coarser sand and below sea level. The distances to areas where the gravel underlying muddy sand as described by present sediment surface lies at these depths are 30 Pantin (1964) ) or they may be i compaction uncon miles to the south-west and only 7 miles to the formities in sediments of more uniform grade north. Considering that there now exists a relief of omposition. Under earlier conditions of high about 12 fm between the lowest reflector and the sea level, as at the present day, sediments in the mud sea floor at the seaward margin of the depression 41

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ there is room for the possibility that an "Egmont STANDS OF SEA LEVEL Gulf" - 15 miles wide and of unknown length - may have existed in Post Shelf Edge time connected The analyses so far attempted indicate a succes with the open sea to the north at depths the same sion of low stands of sea level. as those on the present Outer Shelf (fig. 15). The earliest low sea level is that of Shelf Edge Following the Shelf Edge time erosion, then in time when the outer shelf edge was cut. The average Post Shelf Edge time, the Egmont Gulf stratigraphy present depth in the area considered here is 85 fm , indicates: and sea level at the time of shelf edge formation thus stood at approximately 80 fm. Deposition - on surface (a) under rising and high The deepest of three reflecting horizons (fig. 12) sea level up to present sea floor. that appear at present depths between 72 and 80 fm Erosion - under lowered sea level to produce sur has been correlated with the outer shelf edge. The face (a). two later horizons can be considered as representing Deposition - under high sea level. successive sea level stands near 75 and 70 fm Erosion - under lowered sea level to produce sur respectively. face (b). In the 40 - 60 fm zone a marked change in the Deposition - formation of surface ( c) - under shelf gradient (fig. 4) combined with mid-shelf shell, rising and high sea level on surface (c). pebbles and coarse sands are indicative of a near The lowering in sea level needed to achieve the shore environment. erosion indicated is not clear. If near shore con The concentration of ironsand found at 15 fm ditions!are represented then the fluctuations would over a wide area of the shelf has been ascribed to have been extreme and the low stands could have wave processes operating at a time of Late Glacial approached the sea level of Shelf Edge time. low sea level (McDougall, 1961).

39''�-4-----_j...... -¥----l --+--_:_/.4--riL.,L��-�=:::::�::::...... -- s - --4

-tML Egmont

Fig. 15: A tentative reconstruction of the Shelf-Edge-time shoreline, showing the location of Egmont Gulf. (Echo-sounding traverses of figs. 12a and 12b shown west of Egmont) 42

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ RELATIVE CHRONOLOGY ln present depths of 15 fm the ironsand con From an examination of the shelf morphology centrations have been interpreted as beach deposits associated with glacial features off the south of "Late Glacial" age. Their position in shallower western coast of the South Island Bruun et al., depths than the present mid-shelf coarse sediments (I 958) were able to postulate that the shelf edge suggests a time of formation at a late still-stand of there was cut at a period of low sea level later than sea level in the last glacial substage (table 2). Penultimate Glaciation time and earlier than the This chronology then places all the shelf events in second stadia! of the last Glaciation. and subsequent to the Last Glaciation. The data do Tt is reasonable to assume that a similar time of origin can be ascribed to the Western Shelf in not lend themselves to recognition of relatively high general, for the shelf edge is broadly continuous. (interstadial) levels that might have been located A time of origin at an early (perhaps the first) low at or near present sea level. Similarly evidence of stand of sea level in the Last Glaciation is thus the low stands of sea level that occurred in the indicated. Shelf Edge time can be equated with Penultimate Glaciation would, on the hypothesis early last Glaciation time. In this (first stadial) accepted here, have been destroyed during shelf period the shoreline was deeply indented by the formation. Egmont Gulf. The - 75 and - 70 fm surfaces preserved in the Because of the width of the shelf off the Wanga fill of the Egmont Gulf must be relatively closely nui coast it cannot be clearly shown that the prob associated with it in time and can be ascribed to able Last Interglacial high sea level Rapanui subsequent low stands of sea level in early sub terraces described by Fleming ( 1953) from this area stages of the Last Glaciation. have no relation to the outer shelf. However, where The near shore deposits of the present mid-shelf at -40 to -60 fm may be correlated with a late the shelf is narrow as in Fiordland, then the maximum (perhaps of the last substage) of the morphological discontinuity between Last Glacia Last Glaciation. tion and earlier features is clearly apparent.

TABLE 2. SHELF CHRONOLOGY

------Sea Level (Depth below Age present sea Feature level in ------fathoms)------'- Q) 15-20 "Late Glacial" Last Stadia! of Beach concentration of Ironsand. Boundary between Inner Last Glaciation Very Fine Sand Zone and Fine Sand Zone. ::E z - 0 ii. Last lnterstadial High sea level i== ------'-- ---�------< 40-60

4•

The volcanic constituents of the present shelf south of Tirua Point to Wanganui. North of this sediments have been transported there by a number area they have recognised an older ash from Mt. of mechanisms. Egmont, the mainly andesitic Mairoa shower ex tending north almost to Raglan. Ash: First of these is the direct fall of finevolcanic The magnetite from these and earlier showers ash over wide areas from the adj acent eruptive can thus have been directly emplaced in the marine centres of Mt. Egmont and the Auckland peninsula sediments. On the other hand the presence of mag volcanoes. Some lesser contributions can have netite distributed in fairly uniform proportions arisen directly from the central North Island down the length of a 20 in. core (C 311) argues for volcanoes (Grange and Taylor 1932, Fleming 1953). an extended history of the magnetite as a marine The central area of the North Island that drains sediment. to the west has provided a large area from which If primary subaerial emplacement controlled the subaerial andesitic and rhyolitic ashes and pumice distribution of volcanic components (as these are have been eroded by rivers and transported to the indicated by the magnetite) then some symmetric sea. relation to the origin in Mt. Egmont could be Pre-Recent concentrations of heavy mineral con expected. No such relation is indicated ei ther in the stituents of earlier volcanics have been available distribution of grade of magnetite or of its propor for reworking either on the shelf or as subaerial tion in the total sediment. The area in which the dunes. coarsest magnetite particles are dominant is just south of Mt. Egmont. In the mid-shelf area west Lahar: Around Mt. Egmont, lahar deposits form of Cape Egmont, where the total sediment domi the coastal cliffs in many places. These are recog nant is mud, the magnetite dominant grade is very nisable in the adjacent near shore marine sediments fine sand. Other than this discrepancy and within as concentrations of large boulders and pebbles of limits imposed by available primary grain sizes the andesite. distribution of dominant grade is similar for both Hornblende crystals and fragments are common total sediment and magnetite, though the magnetite constituents of the near shore coarse sediments in tends to be a little finer. Though the anomalous the area near and south of Cape Egmont. At one occurrences of very finesand grade magnetite as a station, (C 181) in 14 fm 20 miles west of Patea, dominant in the Mud Zone could be taken as an crystals up to 3 mm long were abundant. These indication of at least partial primary emplacement may derive from near shore weathering and work of volcanic materials, yet the magnetite is accom ing of the coarse components of lahar deposits. panied by small percentages of non-volcanic frag ments in the very fne sand grades. Ironsands: Magnetite forms 2-5 % of the ash de The weight of information supports the sug posited in the late Egmont ash deposits of the gestion that the present magnetite distribution has Wanganui-Taranaki region (Fleming, 1953). This been effected as ai marine sedimentary process. ash covers superficial deposits that include earlier Some of the magnetite has undoubtedly been con andesitic and rhyolitic ash showers. centrated in near-beach processes at late stands of Grange and Taylor (1932) have mapped the two sea level, and has been rederived from these con Egmont andesitic ash showers that they recognise, centrations (either fromhigh sea level dunes or new extending along the coastline from about 10 miles submerged beaches and dunes).

Origin of Sediments: There are three types of Methods of Emplacement: The near shore occur sources that provide present day marine sedimen rence of mud at river mouths is ascribed to floccu tary material on the sea floor. lation of river-borne fine sedimentary particles on entering salt water. Other than this circumstance, (1) The firstgroup of these comprises the contem the shelf deposits - if all were contemporary - porary sources of primary particles either of allu should reflect simply the tendency of the heaviest \ i um, products of beach wearing or of shore particles to fall out of suspension earlier than the erosion and volcanic ash. fine, together with the superimposed effect of water (2) The second is that composed of unconsolidated turbulence and velocity variations. It is notable, as or poorly consolidated marine sediments emplaced exemplified by the present data, that while the in an earlier phase of marine deposition. Some of variations in water movement cannot readily be these are the deposits that in the Flandrian rise of mapped, yet the variability of sediment grade sea level were formed and then reworked as the sea distribution seems more than can reasonably be transgressed over them, and are only in part able ascribed to this cause. If the water movement to be recognised as such. pattern were to be directly correlated with anoma lous sediment distribution, then a remarkably (3) The third category comprises the mainly coarser steady pattern of distribution of water movement materials of near shore deposits that were formed variations is implied. in earlier low-level stands of the sea that, because The role of relict and reworked sediments in the present-day processes are unable to remove or forming the shelf sediment grade distribution over them, exist as relict sediments out of phase pattern is considerable and in cases such as that \\·ith their environment at the present surface of the studied here is only little inferior to that of the sea floor. present-day primary sediments.

ACKNOWLEDGMENTS

The authors wish to thank, for their assistance at sea, the masters and crews of M.V. Viti and M.V. Taranui; the fellow members of the Institute staff who took part in the cruises and helped with the laboratory work ; and Mr C. T. T. Webb for draughting services.

REFERENCES

BRUUN, A. FR. ; BRODIE, J. W.; FLEMING, C. A. 1955 : GRANGE, L. I.; TAYLOR, N. H. 1932: The Distribution and Submarine Geology of Milford Sound, New Zealand Field Characteristics of Bush-sick Soils. N.Z. Dep. sci. N.Z. J. Sci. Tech. B36 (4) : 397-410. Industr. Res. Bull. 32 : 21-35. McDOUGALL, J. C. 1961 : Jronsand Deposits Offshore from BRODIE, J. W. 1960 : Coastal Surface Currents around New the West Coast, North Island, New Zealand. N.Z. J. Geol. Zealand. N.Z. J. Ceo/. Geophys. 3 (2) : 235-52. Geophys. 4 ( 3): 283-300. FLEMING, C. A. 1953 : The Geology of Wanganui Sub NICHOLSON, D. S. ; FYFE H.E. 1958: Borehole Survey of North division. N.Z. geo/. Surv. Bull. n.s. 52. Island Ironsands from New Zealand to Kaipara Harbour. N.Z. J. Geol. Geophys. I: 617-34. G.�RNER, D. M. 1959: Hydrology of New Zealand Coastal PANTIN, H. M. 1966 : Sedimentation in Hawke Bay. N.Z. Waters. N.Z. Dep. sci. industr. Res. Bull. 138. (N.Z. Dep. sci. indllstr. Res. Bull. 171. (N.Z. oceanogr. Inst. oceanogr. Inst. Mem. 8.) Mem. 28.)

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I sand. elly h s arse sand. o sand. sand. sand. c mud. mud. mud. mud. Sediment sand. fine fine fine sand. fine fine sand. v er mud. mud. mud. ly sand. sand. sand. o l ,, sandy mud. sandy sandy sand. e ery ery fine ery ery ery h v v v fine sand. v v fine sand. s fine fi;�e fine fine sandy fine sandy fine fine fine fine sand. sandy sandy sand. sa�d. sand. sand. sand. ly ddy l arse elly e o h h Muddy Mu Fine sandy' Fine Muddy Mud. Muddy Muddy Fine Muddy Muddy Muddy S Mud. Fine Fine Fine Fine sand Very Very C Shelly Fine Fine Very S Very Very Very Fine h ½ ½ ) re 5 8 8 6 9 4 o n 10 18 (in. C Lengt Cg + Gear S db GP TA DC ms) d h 7 5 5 7 7 7 7 7 u e ho 16 14 19 85 12 13 50 10 12 17 1 52 50 53 38 2 63 80 38 28 2 29 6 7 7 32 30 55 2 25 52 3 28 28 35 43 20 33 31 33 11 20 23 30 31 3 22 20 42 42 489 Dept (fat ontin c l I- 5 5 5 5 ca · · · i I 1 7 9 3 8 5 LE 3 3 5 3 5 7 4 2 4 7 9 2 4 7 9 3 16 11 18 13 11 51 39 13 15 17 19 14 31 61 20 4 59 69 62 11 30 29 21 24 28 B 41 40 miles) A T (Naut Distance* ' ' ' ' ' ' ' 1' 5' 8' 1' 8' 8' 3' 3' 5' 5' 8' 3' 3' 5' 5' 5' 1' 1' 5' 5' 7 3' 3' 5' 2' 2' 8' 8' 5' 5' 2' 2' 8' 8' 8' 6 8' 8' 4' 4' 2' 2' 4' ·8 · · ·2 · · · · · · · · · · · · · · · · · · · · · · · · · · ' ' ' ' ' ' ' ' 1 7 7 7 5' 7 7 7 7 7 7 7 8' 8' 7 0' 7 ng. 13 10- 16 E 18 16 1 I 1 1 11 13 12 35 35 3 35 34 32· 3 53' 35' 35' 43 30 5 5 22 32 38 29 2 1 44' 05 28 4 23' 29' 20' 3 2 25' 25 45 40 24' 24' 42 46 09 44' 0 o ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° L 3 3 3 3 3 3 3 3 3 3 4 4 3 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 n 7 7 4 7 7 4 4 7 4 7 7 7 4 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 4 7 4 7 4 7 4 7 7 4 7 4 o 7 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 17 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 1 1 siti ' ' o 3' 3' 3' 5' 8' 8' 8' 8' 8' 8' 7 7 · · · · · · · · P s 19 19 18' 19 19 50' 39 50' 20' 20' 20' 50' 50' 50' 20' 20' 20' 20' 20 20 20' 39 20' 23' 00' 20' 00' 00' 00' 00' 00' 00' 50' 50' 50' 20' 00' 00' 00' 00' 00' 01' 00' 40' 40' 40' 40' 00' 40' 40' 49' 00' 40' Lat. ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° 38 38 38 38 38 38 38 38 38 38 38 38 39 38 38 38 38 38 39 38 38 38 36 36 36 36 36 38 36 36 38 38 38 38 38 38 39 38 39 38 39 38 38 38 38 39 39 39 39 9 5 J/ 0/59 0/59 6 i! 5/9/59 Date 23/i 21/i 24/10/59 22/10/59 T Line N RA E O TEA O GM MURIWAI MAROKOPA E A HAW 1 1 1 1 5 3 6 5 7 8 4 9 7 3 7 2 4 8 9 0 7 2 7 7 7 7 0 7 7 7 77 7 7 7 . o n 18 18 18 18 265 263 268 285 2 26 2 2 298 2 266 2 300 30 2 1 2 2 264 18 1 181 280 262 286 289 296 299 295 281 29 26 2 2 269 260 282 284 291 293 292 290 283 288 28 o N C C C C C C C C C C C C C C C C Stati C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C � 00 . This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. I To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ I sand. sand. sand. sand, sand. mud. mud. sand. fine sand. sand. fine fine sand. fine fine fine sand. fine fine sand. sand. sand. sand. sand. nd. mud. sand. ,, elly ;; sandy sand. sand. sand. sandy coarse sand. �ery very very �b fine fine very fine fine sand. fin�' very sand. li.d. nd. coarse coarse muddy fine fine';and. fine fine fine fine sl fine sandy sand. fine sand. sand. sand. �a sand. v;:'lly Fine Muddy very Muddy Muddy Muddy Muddy Fine Shelly Fine Shelly Shelly Muddy Shelly Shelly Shelly Mud. Very Very Very Muddy Fine Mudd;' Muddy Very Fine Muddy Muddy Muddy Muddy Muddy Very G ra G Fine Very Fine Fine 7 5 4 0 2 2 8 3 6 9 19 1 1 16 12 1 22 20 26 1 30 20 12 Cg GP + 6 5 6 5 5 3 7 30 18 19 11 1 12 18 98 14 37 74 13 38 88 23 53 65 56 43 34 19 30 61 5 22 43 29 3 70 30 52 67 20 27 85 85 77 33 40 66 45 45 23 34 39 36 27 46 26 73 78 43 10 227 5 5 5 5 5 5 5 5 · · · · · · 5 5 3 8 6 6 5 7 8 9 1 0 2 3 2 4 4 5 9 0·5 7 13 18 11 1 17 17 10 12 17 16 12 14 1 30 19 14 13 16 11 1 18 20 27 12 25 14 18 16 30 25 24 27 20 50 25 61 20 40 ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' 5 3 8 7 7 8 3 8 5 6 9 3 5 5 3 5 4 2 0 4 8 3 8 8 5 2 8 8 2 5 6 5 3 2 6 2 2 9 2 5 4 4 4 · ·5 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ' ' ' ' ' ' ' ' ' ' ' ' 7 7 19 16 14 11 11 18 18 19 16 36 31 37 34 32 18 37 15 59 5 06 38 34 29 24 39 36 33 13 26 21 29 31 26 21 09 47 27 24 25 04 05 09 44 42 23 23 00 34 02 28 20 06 47 20 05 ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 3 3 4 4 4 4 4 4 4 3 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 174 17 17 17 173 17 17 17 17 17 17 17 173 17 ' ' ' 6 6 2 · · · ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' 19 19 20 20 20 20 20 20 20 40 00 00 00 00 00 00 20 20 20 40 40 40 40 40 40 40 40 40 40 40 40 40 00 00 00 00 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° 37° 37 37 38 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 38 37 38 37 38 37 37 37 37 37 37 38 38 38 38 38 38 38 37 38 38 38 38 37 37 37 37 38 36 36 36 36 /59 0/59 10 27/i0/59 26/io/59 25/i 24/ Coastline. N A from GL West MOK.AU RA WAIKATO PIH,{ MURIWAI 1 2 2 4 0 Due 336 328 327 329 326 323 315 331 343 324 319 319 334 335 337 339 320 333 341 325 322 332 313 317 340 330 321 338 318 345 345 346 342 31 348 312 349 35 354 355 357 353 356 311 316 350 347 305 35 358 304 304 360 302 309 31 303 359 * C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C 4:,.. \C

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. I To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ I ,

11d

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fine

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)

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17 3 36 Core 23 22 24 22 22 .\() 24 26 26 '.W 24

Length

Gear

6 7 1

4 ,

0 0

9 5 8 8

9 7

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0 82

78 7 7 72 67 5 39 37 27

22 22 2 2 22 36

1 4 55 5 71 42 5 74 :=;r, 6 6 62 .� 62 66 .\7 9K 61 n

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241

Depth

(fathoms)

continued

I-

5 5 5 5

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2 4 3

2 5

9 7 3 2

5 4 5 5 7 9 0 7 0 4

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11 22 42 .\')

19 1 miles)

13 1 11 3 19 29 5 (,() 5�

40 �7 (1X (,7

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TABLE

(Nauti

Distance*

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' ' ' ' ' ' 5 '

5 5

5 · 5

5 5' 5

5' · ' · -

' ' · ' ' ' · ·5 ' · '

' ·5 · ·5 5 · · ·5

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6 l' 4 8

0' 2 8 9

1 1

4 3

. 8' 4

5 1 8' 18

3 4

2 36 5 19 22 16 36 1 21 l

4 0 0 1

21 I

44 4 39 10 42 4 37 55' 17 32 26 3 21 26 0 29 .\(, 28 42 5 4

27 0 3 4')

° ° ° ° °

° °

° ° ° ° ° ° ° ° " . ,

° ° ' Long. ° ° ' ' ° ° ° °

° ° ° ° ° ° ° " ° ° ° " "

" "

· "

2 2

2 2 2 2 2 3 2 3 3

4 4 4 1 4 3 3 1 1 4 3 4 4

3 1

3 . 3 3 3 3

4" 4 4

72" 2

73 72 7 173 72 73 7.1 73 7J 7 7 72

7. 17 74 17 7 7 7 17 17 17 17 17 17 17 17 17 17 17 173 17 17

17 17 17 17

17 17

173 1

17 17 17 l l 1 17

17 173 17

Position

' ' ' ' ' ' '

' ' ' ' ' ' ' ' '

' ' ' ' ' ' ' '

' ' ' ' 0 '

0' 0' 0 0'

0' 0' 0' 0

0' 0'

0 0' 0' 0' 0' 0' 0' 0' 0 4 0 0 0 0

4 54 54 4 54 54 4 54 54 4 54 54 54 54 54 54 54 54 54

2 2 2 2 2 Lat.

2 2 20 2 20 2 2 2 2 2 2 2

4 4 ()() I)() 00 ()() 00' 00

° ° ° ° ° ° ° °

° ° ° ° ' ° ° ' ° ' °

° ° ° ' ° ° °

° ° ° ° ° ° ° ° ° °

38 9

38 0" 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 39 39 l•) 39 l

39 39

39 39 39 39 39 39 W4 39 39 39 39 3 W4 39 W4 . .

40 40 40 40 4 40

Date

6)5/60

7/5/60

27/1

28/i

Line

/\NUI

ONT

WERA

A!TA

ANG

MOKAU

EGM

4 1

5 1

0 4

16 18

3 31 3 33 3 37 36 38 39

361 362

363 366 36 367 36 368 369 37 371

373 37 372 372 37 376 378 379 379 377 38

4 4 419 4

42 42

423 422 428 426 429 424 427 42 4 4 432 4 4 4 4 4 4 4 44 44 44 442

No.

Station

C C C

C C C C C C C C

C C C C C C C C C C C C C

C C

C C C C C C C C C C C C C C C C

C C C C C C

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I I sand. d. u sand. m sand. shelly gravel. gravel. sand. . fine sand. sand. sand. sand. sand. sand. {d '� d. sandy sand. sand. u sandy sa: coarse coarse very fine fine fine fine fin shelly sandy medium sand. fine sand. fine m m y y ly sand. sand. u sand. sand. sand. sand. sand. y l d< ddy ddy ddy ddy d

GRAIN-SIZE DISTRIBUTION ALONG SAMPLING LINES 2-6 AND 8-10

(See fif" 7). Piha (line 2) : A very fine sand zone extends from the shore the mud having an average percentage of 25 and the fine line to 20 fm, 7 miles offshore. Here, the very fine sand sand 7. Other constituents are present only in minor fraction reaches a maximum of 80 % with the average per quantities. centage of fine sand and very fine sand being 50. The mud From the outer edge of the fine sand zone to the shelf and coarse grades in this zone are negligible. edge there is an increase in very fine sand (reaching 70 %) From 20 fm to approximately 50 fm a fine sand zone is also an increase in mud (reaching 26 %). The fine sand, apparent with a maximum of 63 % fine sand. Very fine sand medium sand, and the coarser fractions become almost and medium and coarse sand average about 15 %, mud is negligible at the 100 fm line. once again negligible. The mud fraction becomes apparent 2 miles from shore From the 50 fm mark to the shelf edge the mud and very and rapidly increases to 47 % 3½ miles from shore in 19 fm. fine sand fractions both increase to approximately 50 %, There is an equally rapid decrease, and by roughly 6 miles each with the fine sand and coarser fractions almost absent. (25 fm) out, the quantity is negligible. This remains constant The amount of mud in the zones from shore to 50 fm out to 30 miles offshore in 40 fm where the percentage rises ranges from 0-11 %. At this point there is an abrupt increase from 2-26 in 10 miles. to 55 % at 54 fm. From 50-100 fm (a mud zone) there is a The coarser fr actions show a slight increase between 6 and steady decrease to 25 %. 30 miles but none of them individually reach more than 7 % WaTheikato maximum (line 3) percentage: of coarse sand is 5 % at 40 fm. andMa rokopa percentages (line become6) : minimal near the shelf edge. There is no specific zonation along this Four zones occur, in which the domi line where the sediments are poorly sorted. The percentage nant sediment of the nearest inshore and the furthest off of coarser fractions (medium sand, coarse sand, very coarse shore is mud, with fine sand and very fine sand zones lying sand and gravel) shows a marked increase from the shore between. to about 17 miles offshore (44 fm) at which point they The near shore mud zone extends out to about 9 miles rapidly decrease, remaining negligible to the shelf edge. (28 fm) and averages about 70 % mud, 12 % very fine sand, Apart from an area in 5-10 fm, where the percentage or 13 % fine sand and negligible amounts of the coarse fractions. mud reaches 20, this component is negligible until 90 fm is A fine sand zone, from 9-35 miles offshore in 60 fm, reached where the percentage abruptly increases reaching 45 contains an average of 4 % mud, 7 % very fine sand, 75 % at 100 fm. fine sand, 10% medium sand, and about 1 % or less of the The proportion of very fine sand is 85 % near the shore coarser fractions. From 35-65 miles offshore (85 fm) is a but, from an area between 3 and 13 miles offshore (6- very fine sand zone with an average of 65 % very fine sand, 30 fm), it ranges from 45 to 12 % then becomes almost 32 % mud, and a very small amount of fine sand. negligible further seawards where the coarser fractions have A second mud zone lies from 65 miles (85 fm) offshore reached a maximum. The proportion then steadily increases to the shelf edge at nearly 70 miles and averages 60 % mud as the coarser fractions decrease seaward. and 36 % very fine sand. Very coarse sand increases by irregular stages to a maxi The percentage of mud increases from 39 % at the shore mum of 12 % at 17 miles (44 fm) and then disappears line to a maximum of 88 %, 4 miles offshore. This rapidly altogether. decreases, almost to zero, 10 miles offshore, and remains Coarse shell fragments only appear between 7 and 40 fm as a small quantity (about 2 %) until about 20 miles offshore withRaglan an (average line 4) :percentage of about 4. when the percentage begins to increase, steadily reaching 80 Two prominent zones occur in the region at the shelf edge. out to about 18 miles (46 fm). These consist of a very fine Individual coarser fractions are in the order of 1 % or less sand zone extending from the shore to 7 miles (25 fm) off alongWa itara the (linewhole 8) line.: shore with an average of 70 % very fine sand, 15 % fine sand Only one well defined zone exists - the and 10 % mud, and a fine sand zone extending from 7-17 mud zone between about 35 and 65 miles offshore (70-76 fm) miles (25-45 fm) offshore. Here the fine sand averages 80 % where the mud averages 66 %, very fine sand 17%, fine sand with the very fine sand being 8 %. Apart from a similar 14 % and a negligible quantity of the coarser fr actions. amount of medium sand, the other constituents are neg Between the shoreline and 13 miles out (27 fm) mud and ligible. very fine sand are the predominant fractions averaging 28 % The third and final zone on this line consists principally oi and 70% respectively. Between 13 and 35 miles offshore, fine sand, very fine sand and mud in roughly equal propor mud, very fine sand and fine sand are all present in varying tions at 20 miles (53 fm) distance from shore, but, fromthat degrees but of similar average percentages - 30, 29, and 33. point as far as the shelf at nearly 30 miles, the mud fraction Medium sand increases slightly to 8 % at 21 ½ miles and then decreases steadily to about 8 % with the very fine sand decreases slowly, becoming non-existent 60 miles offshore. fraction increasing to 60 %. The coarser fractions are negligible for the whole line. From The mud fraction is concentrated in two areas ; from the 35 miles to the shelf edge, mud, very fine sand and fine sand shoreline to about 7 miles (25 fm) offshore,and between 18 are predominant, but the average percentages vary from miles (46 fm) offshore and the shelf edge. Between these two those earlier in the line, mud being predominant with an areas there is virtually no mud at all. The maximum per average of 56 %, then very finesand with 30 % and fine sand centages are at 6 miles (22 fm) 17 %, and at 20 miles (53 fm) with 11 %. 36 %. Mud is present throughout the line reaching two peaks of Coarse sand, very coarse sand, and gravel appear in the maximum percentages of 55 and 84 at 15 miles and 53 miles area 8 miles offshore to the extent of 2 or 3 % each, but offshore (37 and 74 fm). Between these positions the lowest apartAotea from(linethis 5) occurrences: are negligible. percentages are 10 at 21 ½ miles offshore and 11 at 7 miles. A distinct fine sand zone extends from Navigational hazards prevented sampling closer inshore. 25-40 fm offshore. Fine sand remains fairly constant at The coarser fractions (coarse sand to gravel ) are negligible 80-85 % with very fine sand averaging 5 % and mud about inEg allmon thet (line samples 9): from this line. 1 %. Medium sand varies between 3 and 9 % with coarse Apart from a coarse near shore area, the sand, very coarse sand and gravel all being below 2 %. sediment sampled is predominantly mud. This is the only Between the shore and this fine sand zone there is a pre line in the survey on which cobbles and boulders were dominance of very fine sand with an average of 65 %. This sampled, these being found from the shore to 5 miles from is interspersed with mud and fine sand at irregular intervals, the shoreline below Mt. Egmont. 52

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ Coarse sand, very coarse sand, and gravel appear to the contains an average of 73 % fine sand, 20 % very fine sand order of 1 or 2 %, but disappear beyond 5 miles offshore. and negligible quantities of other fractions. A mud zone can readily be defined between 5 and 45 miles The mud zone contains 94 % mud and 5 % very fine sand. offshore, (42-72 fm) with mud averaging 90 %, very fine sand The area from the shoreline to 13 miles offshore (14 fm) 5 %, and fine sand 21/o. Any coarser fractions are non shows two peaks where coarse fractions predominate. These existent beyond 33 miles. From 45 miles offshore to the occur at 8½ miles (14½ fm) where there is 65 % medium sand shelf edge is a composite zone containing mud, very fine and 26 % fine sand. They are isolated occurrences with low sand, and finesand in the following proportions : 45 %, 28 %, percentages of medium sand on either side. At 121· miles and 26 % respectively. As the fine sand percentage increases (l3 fm), there is a concentration of gravel, very coarse sand, the very fine sand percentage decreases. coarse sand, and medium sand showing percentages of 9, The mud fraction between JO and 20 miles offshore re 35, 30, and 19 respectively. Once again these percentages mains constant at 99 % of the total sediment, falling gradually are isolated, rising and falling away rapidly on either side. to a minimum percentage of 41 at 40 miles offshorein 74 fm. Between 20 and 30 miles offshore (26-37 fm) mud, very A steady increase then takes place out to the shelf edge. fine sand and fine sand are the main constituents with an average of 45 % very fine sand and fine sand, and 10 % mud. There is only a small percentage of mud, roughly 2 or 3 %, Hawera (line 10): The two major zones in this area are a between the shoreline and 26 miles offshore, from where it fine sand zone between 13 and 20 miles offshore and a mud increases rapidly out to 40 miles where there is 91 %. At 60 zone from 30 miles to the shelf edge. The fine sand zone miles offshore there is 99 % of mud.

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Aotea Harbour 8, 15, 18 Marakopa 8, 36 ash River 15 in sediments 44 Mokau 29 showers, late Egmont 44 River 8-10, 13, 15, 18, 29-32, 36, 37, 42 showers, Mairoa 44 Muriwai 12, 29 Auckland 8-10, 15, 44 New Plymouth 7-10, 15, 18, 29, 36, 37, 42 Awakino River 8, 9, 13, 1 5, 18 Patea 8, 15, 33, 42, 44 Corer, NZOI Gravity 13, 17 River 8, 9, 13, 15, 18, 37 Piha 29 dredge, cone 17 quartz sands 19, 32, 36, 40 Egmont 8, 33, 35, 40 ash shower see ash showers Raglan 32, 44 Cape 8, 9, 28, 29, 35, 36, 39-41, 44 Harbour 8-10, 15, 18, 36, 37 Gulf 19, 42, 43 Rapanui terraces 43 Mount 9, 10, 15, 18, 30, 31, 33, 36, 42, 44, 52 Recorder, C.S. 7 Grab, shell sands 19, 33, 37-39, 52 Dietz 13 Hayward Orange-peel, 13, 17 South Island 40, 43 Petersen 13 Taranaki 44 lronsand Cruises 7 Bight 29 ironsands 7, 16, 42-44 Taranui, M.V. 7, 13 Kaipara 8 Tirua Point 8, 15, 44 Harbour 8, 9, 12, 15, 29 titaoomagnetite 13, 35, 36 Heads 7 Tongaporutu 8, 9, 13, 15, 18 Karioi, Mount 15, 16 Viti, M.V. 7 Kawhia 8 Waikato River 8-10, 13, 15, 18, 29-3 1, 36, 37 Harbour 8-to, 15, 16, 18, 36 Waitara 36 Lach/an, HMNZS 7, 19 River 8, 9, 13, 15, 18, 29, 36, 37 lahar 15, 44 Waitotara River 15 Mairoa Shower see ash showers Wanganui 8, 15, 29, 43, 44 Manukau Harbour 8-10, 14, 15, 18, 30-32, 36, 37 River 7-10, 13, 15, 18, 29-3 1

Memoir Title Memoir No . Date No. Date Title [l] 1955 Bibliography of New Zealand Oceano 14 1963 Submarine Morphology East of the graphy, 1949-1953. By N.Z. OCEANO North Island, New Zealand. By GRAPHIC COMMITTEE. N. Z. Dep. sci. H. M. PANTIN. N.Z. Dep. sci. industr. industr. Res. geophys. Mem. 4. Res. Bull. 149. [2] 1957 General Account of the Chatham Is 1 5 In prep. Marine Geology of Cook Strait. By lands 1954 Expedition. By G. A. J. W. BRODIE. N.Z. Dep. sci. industr. KNOX. N.Z. Dep. sci. industr. Res. Res. Bull. Bull. 122. 16 1963 Bibliography of New Zealand Marine 3 1959 Contributions to Marine Microbiology. Zoology 1769-1899. By DOROTHY Compiled by T. M. SKERMAN. N.Z. FREED. N.Z. Dep. sci. industr. Res. Dep. sci. industr. Res. lnf Ser. 22. Bull. 148. 4 1960 Biological Results of the Chatham Is 17 1965 Studies of a Southern Fiord. By T. M. lands 1954 Expedition. Part 1. SKERMAN (Ed.) N.Z. Dep. sci. Decapoda, Brachyura, by R. K. industr. Res. Bull. 157. DELL; Cumacea, by N. S. JoNEs ; Decapoda, Natantia, by J. C. 18 1961 The Fauna of the Ross Sea. Part 1. y ALDWYN. N.Z. Dep. sci. industr. Ophiuroidea. By H. BARRACLOUGH Res. Bull. 139 (1). FELL. NZ. Dep. sci. industr. Res. Bull. 142. 5 1960 Biological Results of the Chatham Islands 1954 Expedition. Part 2. 19 1962 The Fauna of the Ross Sea. Part 2. Archibenthal and Littoral Echino Scleractinian Corals. By DONALD F. derms. By H. BARRACLOUGH FELL. SQUIRES. N.Z. Dep. sci. industr. Res. NZ. Dep. sci. industr. Res. Bull. Bull. 147. 139(2). 20 1963 FI a b e II u m r u b r u m ( Q u o y a n d 6 1960 Biological Results of the Chatham Gaimard). By DONALD F. SQUIRES. Islands 1954 Expedition. Part 3. N.Z. Dep. sci. industr. Res. Bull. 154. Polychaeta Errantia. By G. A. KNOX. 21 1963 The Fauna of the Ross Sea. Part 3. N.Z. Dep. sci. industr. Res. Bull. Asteroidea. By HELEN E. SHEAR 139(3). BURN CLARK. N.Z. Dep. sci. industr. 7 1960 Biological Results of the Chatham Sci. Bull. 151. Islands 1954 Expedition. Part 4. 22 1964 The Marine Fauna of New Zealand : Marine Mollusca, by R. K. DELL; Crustacea Brachyura. By E. W. Sipunculoidea, by S. J. EDWARDS. BENNETT. N.Z. Dep. sci. industr. Res. N.Z. Dep. sci. industr. Res. Bull. Bull. 153. 139(4 ) . 23 1963 The Marine Fauna of New Zealand: 8 1961 Hydrology of New Zealand Coastal Crustaceans of the Order Cumacea. Waters, 1955. By D. M. GARNER. By N. S. JONES. NZ. Dep. sci. N.Z. Dep. sci. industr. Res. Bull. 138. industr. Res. Bull. 152. 9 1 962 Analysis of Hydrological Observations 24 1964 A Bibliography of the Oceanography of in the New Zealand Region 1874- the Tasman and Coral Seas, 1860- 1955. By D. M. GARNER. N.Z. Dep. 1960. By BETTY N. KREBS. N.Z. Dep. sci. industr. Res. Bull. 144. sci. industr. Res. Bull. 156. 10 1961 Hydrology of Circumpolar Waters 25 1965 A Foraminiferal Fauna from the South of New Zealand. By R. W. Western Continental Shelf, North BURLING. NZ. Dep. sci. industr. Res. Island, New Zealand. By R. H. Bull. 143. HEDLEY, c. M. HURDLE, and L. D. J. BURDETT. N. Z. Dep. sci. industr. Res. 11 1964 Bathymetry of the New Zealand Region. By J. W. BRODIE. N.Z. Dep. Bull. 163. sci. industr. Res. Bull. 161. 26 1964 Sediments of Chatham Rise. By ROBERT M. NORRIS. N.Z. Dep. sci. 12 1965 Hydrology of New Zealand Offshore Waters. By D. M. GARNER and industr. Res. Bull. 159. N. M. RIDGWAY. N.Z. Dep. sci. 27 1965 The Fauna of the Ro,e Sea. Part 4. industr. Res. Bull. 162. Mysidacea, by OUYE S- TATTERSALL; 13 1961 Biological Results of the Chatham Sipunculoidea, by s. J. EDMONDS Islands 1954 Expedition. Part 5. N.Z. Dep. sci. industr. Res. Bull. 167. Porifera : Demospongiae, by PATRI 28 1966 Sedimentation in Hawke Bay. By H. CIA R. BERQUIST; Porifera : Keratosa, PANTIN. N.Z. Dep. sci. industr. Res. by PATRICIA R. BERGQUIST ; Crusta Bull. 171. cea Isopoda : Bopyridae, by R. B. PIKE; Crustacea Isopoda: Serolidae, 29 1964 Biological Results of the Chatham by D. E. HURLEY ; Hydroida, by Islands 1954 Expedition. Part 6. PATRICIA M. RALPH. N.Z. Dep. sci. Scleractinia. By D. F. SQUIRES. N.Z. industr. Res. Bull. 139 ( 5). Dep. sci. industr. Res. Bull. 139(6 ) .

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/ Memoir Memoir No. Date Ti tle No. Date Title 30 1966 Geology and Geomagnetism of the 35 1 966 The Marine Fauna of New Zealand : Bounty Region east of the South Spider Crabs. Family Majidae (Crus Island, New Zealand. By DALE C. tacea, Brachyura). By D. J. GRIFFIN. KRAUSE. N.Z. Dep. sci. industr. Res. N.Z. Dep. sci. industr. Res. Bull. 172. Bull. 170. 36 1966 Water Masses and Fronts in the South- 31 In prep. Contribution to the Natural History of ern Ocean South of New Zealand. By Manihiki Atoll, Cook Islands. Ed. TH. J. HOUTMAN. N.Z. Dep. sci. C. A. MCCANN. N.Z. Dep. sci. industr. Res. Bu/l. 174. industr. Res. Bull. 37 In press The Marine Fauna of New Zealand: Porifera, Demospongiae. Part I Tet 32 In press The Fauna of the Ross Sea. Part 5. ractinormorpha and Lithistida. By General Accounts, Station Lists, PATRICIA R. BERGQUIST. N.Z. Dep. and Benthic Ecology. By JOHN S. sci. industr. Res. Bull. BULLIVANT and JOHN H. DEARBORN. N.Z. Dep. sci. industr. Res. Bull. 38 In press The Marine Fauna of New Zealand: Intertidal Foraminifera of the Coral 33 In press The Submarine Geology of Foveaux Zina officinalis zone. By R. H. HEDLEY, Strait. By D. J. CULLEN. N.Z. Dep. c. M. HURDLE, and I. D. J. BURDETT. sci. industr. Res. Bull. N.Z. Dep. sci. industr. Res. Bull. 34 In prep. Benthic Ecology of Foveaux Strait. By 39 1967 Hydrology of the Southern Hikurangi E. W. DAWSON. N.Z. Dep. sci. Trench Region. By D. M. GARNER. industr. Res. Bull. N.Z. Dep. sci. industr. Res. Bull. 177.

R. E. OWEN, GOVERNMENT PRINTER, WELLINGTON, NEW ZEALAND-1967 1,625/12/65- 14101/66 A