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Hautotara, Te Muna and AhiaruheFormations, middle to latePleistocene, Wairarapa, NewZealand.J. D. Collen & P. Vella aa Department of Geology , Victoria University ,WellingtonPublished online: 05 Jan 2012.

To cite this article: J. D. Collen & P. Vella (1984) Hautotara, Te Muna and AhiaruheFormations, middle to late Pleistocene, Wairarapa, New Zealand., Journal of the RoyalSociety of New Zealand, 14:4, 297-317, DOI: 10.1080/03036758.1984.10421732

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© Journal of the Royal Society of New Zealand, Volume 14, Number 4, 1984, pp. 297-317

Hautotara, Te Muna and Ahiaruhe Formations, middle to late Pleistocene, Wairarapa, New Zealand.

J. D. Collen and P. Vella*

The Hautotara, Te Muna and Ahiaruhe Formations are formally described for the first time. The Hautotara Formation contains the littoral marine and estuarine deposits of the Huangarua Cyclothem together with underlying freshwater deposits which have been added for mapping convenience, and is considered to be late Marahauan (c. 1.2 to 1.05 Myr) in age. The Te Muna Formation is a conformable sequence, 366 m thick, containing fifteen members. Alluvial gravels alternate with freshwater blue-grey silt and sand with lignite layers, tree roots in growth position and occasional paleosols. The Te Muna Formation also contains loess at one horizon, and localised rhyolitic tephra beds. The tephras and preliminary paleomagnetism indicate a Castlecliffian age (c. 1.0 to 0.4 Myr). The Ahiaruhe Formation consists of alluvial gravel varying from a few metres to more than 80 m in thickness, interbedded with water-laid, partly loessic silts locally containing Mount Curl Tephra (c. 0.23 ± 0.04 Myr; equals Ahiaruhe Tephra). It has a tilted but still well-defined depositional surface at the top forming terraces, and passes laterally westward to thick blue-grey lacustrine silt with a moa footprint and also containing Mount Curl Tephra. The tephra indicates an age greater than 0.2 Myr for the the base of the Ahiaruhe Formation and less than 0.26 Myr for the top. Kawakawa Tephra in overlying loess indicates an age greater than 0.02 Myr. The three formations correspond to most of the time represented by the late Nukumaruan Stage, Castlecliffian Stage and early Hawera Series. We infer that their deposition was controlled by climatic fluctuations and associated glacio-eustatic sea-level changes coincident with Milankovitch cycles, superimposed on secular vertical tectonic movements.

Keywords: Ahiaruhe Formation, Hautotara Formation, Milankovitch cycles, Pleistocene, sea-level changes, stratigraphy, Wairarapa.

INTRODUCTION The lithostratigraphic names Hautotara Formation, Te Muna Formation and Ahiaruhe

Formation have been used for some time in manuscripts and on unpublished maps. The Hautotara Formation, the lowest of the three, disconformably overlies Pukenui Limestone Formation (Vella and Briggs, 1971) and consists offreshwater, estuarine and near-littoral marine deposits. The Te Muna Formation overlies Hautotara Formation with slight angular unconformity, overlapping on to Pukenui Limestone, and consists entirely of freshwater deposits. The Ahiaruhe Formation unconformably overlies Pukenui Limestone and older strata at various places, but has not yet been shown to overlie Te Muna or Hautotara formations. It consists mainly of freshwater deposits with some loessic components.

The type sections and and most studied area of Hautotara and Te Muna formations are in the Huangarua Syncline (new name), a northeast-trending structure that obliquely crosses the Huangarua Valley a few kilometres southeast of Martinborough town (Figs. 1, 2). The Huangarua Syncline is an asymmetrical box-fold that is probably draped over block-faulted Mesozoic basement. The axis lies close to its northwest side, which is defined by steep southeastward dips in Te Muna, Hautotara and older formations

Department of Geology, Victoria University, Wellington.

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298 Journal of the Royal Society of New Zealand, Volume 14, 1984

Fig. i-Locality map.

Fig. 2 -Geological map for Hautotara and Te Muna formations in type area along Huangarua River. Pre-Hautotara geology and structure simplified for clarity.

DVounger alluvium ~>::::;:J Te Muna Formation

13·~,;:;o~Ahiaruhe Formation _Hautotara Formation

~-.P"5iiiiP"'Iii

r7:':1Pukenui Lmst. Fmn. ~ (LOWER PLEISTOCENEi

r_-_-_-_JGreycWs Formation & ---_-_-_ Mangoopon Mst. Fmn.

(PLIOCENE-lwr PLEISTOCENE)

"m GRID TAKEN FROM NZMS 260 SHEET S 27

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Collen, Vella - Hautotara, Te Muna and Ahiaruhe Formations 299

exposed in the banks of the Huangarua River within and immediately south of the Huangarua Fault Zone (Fig. 2). The southeastern margin of the syncline is defined by a monoclinal flexure 1.5 to 2 km distant from the axis. Here Pukenui Limestone, Hautotara and Te Muna formations all dip at high angles, commonly 45 a and locally even 70 0

. Erosion of soft Hautotara Formation from resistant Pukenui Limestone has formed a linear scarp along the monocline, but no evidence of faulting has been found. Between the monocline and the axis of the syncline Te Muna Formation dips gently northwestward at about 100 near the monocline, reducing gradually to zero at the axis. The monocline was probably formed by folding of Cenozoic strata over faulted Mesozoic basement rocks.

The Hautotara Formation and most of the Te Muna Formation are weakly consolidated, and form a subdued landscape with few exposures except along the Huangarua River. Some conglomerate layers in the Te Muna Formation are locally firmly cemented by iron oxides (the "ferruginous conglomerates" of McKay, 1879) and stand out prominently on hillsides, but the cementation is not persistent enough to enable them to be mapped continuously. Exposures in the banks of the Huangarua River are discontinuous, but because the river meanders and runs very obliquely across the strike of the southeast flank of the syncline, it has been possible to reconstruct almost the entire section with only one substantial unexposed interval in the upper part of the Te Muna Formation.

HAUTOTARA FORMATION The term Hautotara beds was used by Hector (1884) without definition for blue-grey

silts, grits and conglomerates at Manawatu Gorge which he correlated with beds at Hautotara. As now defined, the name probably represents a more restricted usage than that of Hector.

Most of the Hautotara Formation is the Huangarua Cyclothem (Vella, 1963). For mapping convenience it has usually been found best to take the highest cemented coquina bed as representing the top of the underlying Pukenui Limestone Formation (Vella and Briggs, 1971). Consequently, at Hautotara (junction of the Ruakokopatuna and Makara Rivers), freshwater strata that were treated as part of the Eringa Cyclothem (Vella, 1963), which approximately corresponds to Pukenui Limestone, have been mapped as the lower part of the Hautotara Formation (Fig. 3).

The type section of the Hautotara Formation is the same as for the uppermost Eringa Cyclothem plus the Huangarua Cyclothem. It extends along the east bank of the Huangarua River for a distance of 400 m downstream from the junction of the Ruakokoputuna and Makara Rivers (marked by Banana Bridge on White Rock Road). The sequence is shown by Vella (1963, fig. 3). The original description of the Huangarua Cyclothem is here supplemented (Fig. 3) with data from Rodley (1961) who measured and described with great care that part of the section that was visible to her. The freshwater beds at the top of the Eringa Cyclothem described by Vella (1963) were mostly covered by earthworks during construction of Banana Bridge. In addition, successful river conservation work has diverted the river from the east bank downstream from Banana Bridge, so that much of the section here is now overgrown. It is still the most complete section known through the formation, however, and it is fortunate that the earlier descriptions are available.

Relationship with underlying Pukenui Limestone Formation The contact between Hautotara Formation and Pukenui Limestone Formation has

been seen clearly at only one place, on the east bank of the Huangarua River 1 km south of Te Muna (S27/18658850; Metric grid references are taken from NZMS 260 Sheet S27, Martinborough (1st Edition, 1980)). There, unconsolidated gritty calcareous sand of Hautotara Formation rests on a solution-pitted surface of hard Pukenui Limestone. Scattered well-rounded pebbles and cobbles of Meozoic sandstone, and occasional worn and bored calcareous concretions from underlying late Cenozoic formations lie on the limestone surface but are not cemented to it; and the limestone at that site contains no

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en Q) L. -Q)

E

TE MUNA FORMATION

4O-i-~ Co" •• " .......... ..1 ~cross-bedded sands with Chione shellbed .... ':.: ... : .. ':.:'; In basal metre

----...........

30-1::: :::: :::::

20

bored contact Fig.6

contact nof exposed

Zethalia sands- coarse, well sorted, friable brown sandstone Fig.5

~~ ,"".Iome,ot. w;1\, wom T .w'" volve. .~.:.i.;.?.:: interbedded silts, sands and peat with ;;;;;;;;;;;; basal conglomerate

lO'~.;;c;,;;o:,; .

o~·

argillaceous sandstone with well preserved bivalves

PUKENUI LIMESTONE FORMATION

z o ~ ~ a::: o u.

« a::: « b ~ :::> « :::r:

Fig. 3 - Stratigraphic column of Hautotara Formation, Huangarua River. Data from Rodley (1961) and Vella (1963).

large clasts. The contact is evidently an erosion surface. Four kilometres to the northeast, a deeply incised creek flowing from Windy Peak to the Huangarua River exposes a section at the base of the monocline on the southeast side of the Huangarua Syncline. There, the contact is marked by a creamy-white clay about 100 mm thick, which is considered to be a paleosol indicating terrestrial weathering probably without significant erosion. In the type area the contact is probably at least a minor disconformity, because during a change from marine to freshwater conditions, continuity of deposition, whether due to progradation or to a change in relative sea-level, requires unusual circumstances (Vella, 1963).

Everywhere that Hautotara Formation has been found it is underlain by upper Pukenui Limestone, and there is evidently little or no angular discordance. We consider that the contact is usually a disconformity probably representing only a slight time intervaL

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Collen, Vella-Hautotara, Te Muna and Ahiaruhe Formations 301

Fig. 4- Weathered outcrop of Zethalia sand member of Hautotara Formation in type section. Photo shows well sorted, friable sandstone with abundant Zethalia. Hammer Length is 327 mm.

Fig. 5 - Barytellina siltstone member of Hautotara Formation in type section, showing paired valves of Barytellina anomalodonta. Photo width 0.4 m.

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302 Journal oj the Royal Society oj New Zealand, Volume 14, 1984

Distribution Hautotara Formation has been mapped for a distance of6 km northeast from the type

locality as a narrow linear strip along the base of the monocline scarp at the southeast side of the Huangarua Syncline (Fig. 2). It has also been identified underlying Te Muna Formation and overlying Pukenui Limestone over a distance of 4 km along Blue Rock Stream from its junction with Ruakokopatuna River, 4 km southwest of the type locality. An isolated exposure of grey silts with estuarine fossils (Chione, Modiolus) interbedded in alluvial conglomerate in Whangaehu Stream (S27/23509410), about 1 km north of Popes Head, may be Hautotara Formation.

At the growing Gladstone Anticline (Kennett, 1964), 27 km north-northeast of the type locality, the upper part of Gladstone Formation, consisting of freshwater (lignite-bearing) silts and overlying richly fossiliferous marine brown-grey, cross-bedded sands (Kennett, 1964), are here considered to represent Hautotara Formation. We have mapped the underlying part of the Gladstone Formation as upper Pukenui Limestone Formation. We consider that the weakly consolidated, sandy, well-rounded conglomerate and fossiliferous sand overlying Pukenui Limestone, probably with a strong on-lap contact, on the western flank of Maungaraki Range east and northeast of Gladstone are also Hautotara Formation.

Marine sands containing Chione stutchburyi and interbedded with conglomerate in the western foothills of the Aorangi Range (S27/01288655), east of Lake Wairarapa, may represent Hautotara Formation but could be considerably younger.

Paleontology The marine deposits are littoral to very shallow subtidal facies with few age-diagnostic

fossils. The bivalves Tawera suhsulcata (Suter), Barytellina anomalodonta Finlay and Chione stutchburyi aassitesia Finlay are the chief evidence for Nukumaruan age (Rodley, 1961; Vella, 1963). Vella (1963) reported a single uncollectable specimen of Pelicaria convexa Marwick in the type section, but no further specimens have been found. Other common molluscs include Zethalia zelandica Adams, Zenatia acinaces (Quoy and Gaimard), Amphidesma subtriangulatum (Woods), Tellina liliana Powell, Divaricella sp., Mylitella sp. and Nucula sp. Foraminiferal assemblages from the fully marine sandy facies (e.g. Zethalia sand member; Figs. 3, 4) are dominated by the benthic species Notorotalia zealandica Vella and Elphidium novozealandicum Cushman, and those from the Barytellina siltstone member (Figs. 3, 5) by ZeafioTilus paTri (Cushman) and Nonionellinafiemingi (Vella). Planktonic foraminifera are rare.

The marine beds assigned to Hautotara Formation at Gladstone, and on the Maungaraki Range to the east and northeast, contain Pelicaria media (Marwick), which elsewhere is restricted to the Pukenui Limestone.

Paleomagnetism The Barytellina mudstone member is the only part of the Hautotara Formation that

is consolidated enough to provide suitable paleomagnetism samples, and it has reversed polarity (Kennett et al., 1971). Most of the underlying Pukenui Limestone Formation is normally magnetised and is considered to represent the Olduvai (equals Gilsa) Normal Event that terminated about 1.6 Myr ago (Kennett et al., 1971). Reversed polarity has now been determined in muddy sandstone near the top of Pukenui Limestone Formation, and Hautotara Formation is therefore somewhat less than 1.6 Myr old. The top of the Nukumaruan Stage is slightly older than 1.0 Myr (Seward, 1974, 1979), and this is in agreement with reversed polarities correlated with the late Matuyama Interval in the lower half of the Te Muna Formation overlying Hautotara Formation.

Age and Correlation of the Hautotara Formation The age of the Hautotara Formation probably lies between about 1.8 and 1.05 Myr.

It evidently represents part of the Marahauan Substage and probably is late Marahauan, and perhaps a direct correlative of the Maxwell Group at Wanganui (Fleming, 1953).

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Conditions of Deposition The greater part of the Hautotara Formation has been described as a sedimentary

cycle, which in turn has been attributed to a glacio-eustatic fluctuation of sea-level (Vella, 1963). The cycle commenced with subaerial conditions, represented by the basal freshwater deposits at the type locality, by the solution-pitted surface of upper Pukenui Limestone at the contact in Huangarua River, and by the presumed subaerial paleosol further northeast. The initial subaerial phase was probably brief. The start of submergence is indicated by littoral conglomerate with abundant Tawera at the type section, and by the few scattered pebbles and cobbles on the solution-pitted limestone surface. Submergence climaxed with shalIow subtidal open coast conditions, represented by fossiliferous cross-bedded calcareous medium sand (Zethalia sand at the type locality; Fig. 4). The sand is well sorted, mud-free and slightly negatively skewed. Occasional conglomerate layers within it have erosional lower contacts and gradational upper contacts, and could be storm-deposits. The Barytellina siltstone (Fig. 5), with common double-valved fossils of the infaunal bivalves Barytellina and Chione, is an estuarine deposit indicating re-emergence, and is the youngest known deposit containing marine fossils in the Huangarua Valley.

The possibility that the sedimentary cycle was caused by a vertical tectonic oscillation is discarded for two reasons. First, data for the last few hundred thousand years show that vertical tectonic movements have been not oscillatory, but unidirectional (Bloom et at., 1974; Ghani, 1974, 1978; Lensen and Vella, 1971; Mesolella et at., 1969). Second, glacio-eustatic sea-level changes certainly must have affected all sedimentation close to sea-level (terrestrial or marine) during the Quaternary Period.

The Hautotara Formation contains one complete sedimentary cycle, and the top of an underlying one. The Pukenui Limestone Formation below contains five complete cycles and part of a sixth one at the top (the so-called minicyclothems of Vella, 1963). The base of the Pukenui Limestone is paleomagnetically dated at slightly less than 1.8 Myr old (Kennett et al., 1971), and the top of the Hautotara Formation, if correctly correlated with late Marahauan, is not younger than 1.05 Myr (Seward, 1974). The seven sedimentary cycles within the two formations thus represent a total time of approximately 0.7 Myr, i.e., 100,000 years per cycle. Milankovitch calculations predict that the major climatic cycles during the Quaternary took about that length of time (Milankovitch, 1938; Hays et at., 1976). We conclude that the Hautotara Formation represents a time interval between 0.1 Myr and 0.15 Myr long, probably between 1.2 and 1.05 Myr B.P.

TE MUNA FORMATION The Te Muna Formation is described here for the first time. The name is taken from

Te Muna Station, on the west side of Haungarua River. The type section extends along the Huangarua River from 1 km south of Te Muna (S27/186887) to 2.7 km north of Te Muna (S27/198919). The stratigraphic column (Fig. 6) summarises present knowledge of the sequence.

The estimated thickness of strata in the type section is 366 m. The top of the formation is not preserved at the river, but sloping ridges to the east appear to represent remnants of a depositional surface and, when projected across the river, suggest that only a few tens of metres of strata are missing.

Fifteen members are recognised, numbered consecutively from the base upwards. They comprise a basal member of rusty-stained conglomerate and cross-bedded sand, followed by seven alternations of blue-grey silt and rusty-stained conglomerate (Fig. 7), with occasional intercalations oflignite, current-bedded sand and, at one horizon, tephra and loess. Through most of the formation, conglomerates are thin compared with the finer grained deposits, but in the top 100 m the reverse is true.

Layers of lignite, and dark brown to black lignitic clay, have been observed in all blue-grey silt layers except the two thin members 12 and 14 (Fig. 6) near the top of the formation. Lignified wood also is common as transported logs and as roots and trunk bases in growth position. Cross-bedded sands in Member 6 contain a number of randomly oriented, closely interlocked logs, possibly representing a fossil log jam or driftwood piled on a lee lake shore. Flecks of carbonaceous material occur in most of the blue-grey silts.

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300

200

(/) Q) ... +-' Q)

E

iPALYNOLOGICAL SAMPLES

jNRM PALEOMAGNETIC

I rMEMBERS

POLARITIES

,o;oooo~oof27/ I 15 era 0 era 0 FB3 iN 1-14

o 0 0 0

• ~ 00 ~ 0 o 000 00

0°0°°0 o 0 0 0

~co~o Fa6

o 0 0 0 Fa7 rN ~ 0 0 ~ 0

o 0 0 0 0 0 F 88 fB9 ~N -? -

0'00

0

?

~

f45 L?

, 41 f 90

f 43 f49

f 91

13

12 II 10 9

8

7

covered interval

many tree roots in growth posi tion

covered interval

6c I conglomerate lenses I!,.aleosols

-6b :I_ Te Muna paired tephra and loess, paleosol

, at base

100~

60 I"-many fossil logs tree roots ingrowth

5----i posi tion

o

f44 ~ R 4 3 ~

f 92

~ o 0°0

. :: .. - f 46

R R

R

2

tree roots ingrowth position

---L--Lcontact covered

HAUTOTARA FORMATION (here enti rely marine)

PUKENUI LlMESTON E FORMATION

~ Conglomerate D ~ with channelled ,,' :", Sandstone

~ Cross-bedded ~sandstone

base

b=-::=::1 Silstone,lignitic B Tephra Claystone, Lignite

z o ~ ~ 0:: o u-

« z :::> ~ w f--

~

Fig. 6-Generalised stratigraphic column for type section ofTe Muna Formation, Huangarua River, showing horizons of palynological and paleomagnetism samples, and subdivision into numbered members.

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Fig. 7 -Cross-bedded conglomerate of Member 5 of Te Muna Formation, overlain with sharp contact by siltstone of Member 6a; true right bank of Huangarua River opposite Te Muna station.

Fig. 8- Upper (A) and lower (B) tephras of Te Muna paired tephra beds, true right bank of Huangarua River opposite Te Muna Station. See text for description of sequence. Beds are 0.6 m apart.

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Fig. 9-Angular unconformity between Hautotara and Te Muna formations in true right bank, Huangarua River, in northwest flank of Huangarua Syncline. Conglomerates of Te Muna Formation dip 10° to the southeast (right) at top and left of exposure, overlying with channelled erosion surface steeply dipping (70° to southeast) fossiliferous sandstone and conglomerate of Hautotara Formation. Fault plane dipping at 70° to southeast, at left of shadowed area, is arrowed.

On the east bank of the river, opposite Te Muna homestead and a few metres stratigraphically above the previously mentioned cross-bedded sands of Member 6, two 100 mm thick beds of rhyolitic ash, about 1 m apart, occur within a yellow-brown weathered, fine-grained sequence that is unique in the formation (Fig. 8). Mottled yellow-brown silty clay below the lower ash is subaerially weathered material that was originally blue-grey silt. Silty clay of similar colour but slightly different texture between the two ash beds and above the upper one is considered to be loess (Mr. C. G. Vucetich, pers. comm. 1981). The two ash beds are probably primary airfall deposits, but further field and laboratory examination is needed to confirm this. The complete yellow-brown weathered sequence is about 5 m thick, and contains two paleosols near the top. It is distinguished as Submember 6B (Fig. 6), and the two rhyolitic ash beds are informally named Te Muna paired tephra beds.

A covered interval between 196 and 224 metres above the base of the formation could possibly conceal another conglomerate member.

Relationship with Underlying Formations The only known clear exposure of the contact between Te Muna and Hautotara

formations is a strong angular unconformity in the steeply dipping northwest flank of the Huangarua Syncline, exposed in the east bank of Haungarua River 300 m upstream from Hinakura Road (Fig. 9). Conglomerates, silts and fossiliferous cross-bedded sands (Chione, Barytellina, Zethalia) of Hautotara Formation dip southeast at 70°, while overlying Te Muna conglomerate dips southeast at 10°, and the contact is deeply channelled with relief of up to 2 m. On the gently dipping southeast flank of the syncline the contact is not clearly exposed anywhere, but it can be located to within about 1 m on the Haungarua riverbed 3.5 km south of the axis of the syncline. There, the dips of the beds above and below the contact are the same. However, at the base of the monoclinal scarp

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on the southeast side of the Huangarua Syncline, towards its northen end, Te Muna Formation overlaps the Hautotara Formation and rests directly on Pukenui Limestone (Fig. 2); and alongside Hinakura Road, 1 km east of Popes Head, it rests on eroded and channelled fossiliferous sandstone representing the lower or middle part of the Pukenui Limestone. We conclude that the base of the Te Muna Formation is an angular unconformity at most places, but that the difference in dip of the beds above and below is slight except in the steeply dipping limb of the Huangarua Syncline.

Probably the Te Muna Formation does not only overlap onto the older strata on the southeastern side of the Huangarua Syncline, but also onlaps, with the base becoming progressively younger eastwards. The contact with the Hautotara Formation probably represents only a brief time interval near the centre of the Huangarua Syncline.

Distribution Rather strongly folded and faulted silts and weakly cemented conglomerates, dipping

generally at 50 to 30 0 and locally at up to 60 0 , rest unconformably on Mesozoic greywacke and late Miocene and Pliocene sandstone and mudstone (Bates, 1967), and form subdued foothills on the western side of Aorangi Range to the east of Lake Wairarapa. Part or all of these represent Te Muna Formation. The formation may be thicker there than at Huangarua River, but exposures are very limited and the stratigraphy is not yet understood. Conglomerates with abundant lignified tree remains on the south western shores of Lake Wairarapa and the western side of Lake Onoke may also represent Te Muna Formation.

In a low anticline barely breaking the flatness of the Wairarapa Plains immediately east of Carterton, the Carterton Brickworks formerly worked blue-grey siltstone with a lignitic horizon and thin interbedded rusty-stained conglomerate. In the Tiffin Anticline, with strong topographic expression, 6.5 km southeast of Carter ton, silt and conglomerate are poorly exposed in weathered road cuttings, and the Carterton Brickworks for a time exploited carbonaceous blue-grey silt and sand with rusty-stained conglomeratic lenses. The siltstones are presumed to be freshwater lake deposits, and the sequence resembles Te Muna Formation, but no tephras or other means of dating have yet been found in it and correlation with Te Muna Formation is tentative.

Along the western edge of the Maungaraki Range east and northeast of Gladstone, rusty-stained conglomerate, freshwater silts and pale grey to white fine quartz sands form low hills. They dip northwest at angles of up to 20 0

, and conformably or nearly conformably overlie presumed Hautotara Formation; they probably also represent the Te Muna Formation.

Palynology Palynological samples from fine-grained members in the type section were examined

by Ms M. Dixon, formerly at New Zealand Geological Survey. No age-diagnostic species were found, and all assemblages examined indicate vegetation similar to recent low altitude Wairarapa rain forest. The lowest samples in the formation indicate some marine influence.

Paleomagnetism Paleomagnetic polarities of blue-grey silt samples from the type section are shown on

the stratigraphic column (Fig. 6). No magnetic cleaning tests have yet been applied to these samples. The reversed polarities in Members 2 and 4 are likely to be valid, but the normal polarities in Members to, 12 and 14 are suspect because of the possibility of a present field normal overprint. The top of the Olduvai Normal Event (1.6 Myr old) is within the Pukenui Limestone Formation and consequently the Te Muna Formation is significantly younger than 1.6 Myr. The lower part, up to Member 4, represents part of the late Matuyama Interval, older than 0.7 Myr; the upper part, from Member 10, probably represents part of the Brunhes Interval, younger than 0.7 Myr; while Members 5 to 9 with uncertain polarities may be either younger or older than 0.7 Myr.

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Tephras Widely distributed rhyolitic tephras of Quaternary age in New Zealand are assumed

to have originated in the Taupo Volcanic Zone. The oldest known tephras in Wanganui Basin are of Marahauan age and relatively thin (Seward, 1976), have not been detected in southern Hawkes Bay, and are unlikely to have reached as far south as Wairarapa. The oldest thick Quaternary tephra marks the base of the Castlecliffian Stage in Wanganui Basin (Pakihikura Pumice, equals part of Makirikiri Tuff of Fleming, 1953) and in southern Hawkes Bay (Lillie, 1953), and all known thick tephras older than the Mount Curl Tephra are confined to the Castlecliffian Stage. Only the largest of the eruptions that produced the tephras could be expected to extend deposits to Wairarapa, and it follows that all tephras older than Mount Curl in the Quaternary of Wairarapa are probably Castlecliffian in age.

Tephras have been found in the Te Muna Formation at the following six sites, listed from south to north: 1. North bank of Blue Rock Stream, 1.4 km upstream from junction with

Ruakokopatuna River, grid reference S27/12808475; a 1 m thick unbedded blocky rhyolitic tephra informally named Duggan Ash by Thomson (1980) and tentatively correlated on mafic mineralogy with the Potaka Pumice Member of the Kaimatira Pumice Sand Formation (zircon fission-track date of 0.64 ± 0.18 Myr; Seward, 1979).

2. West bank of Huangarua River at sharp bend 1.3 km downstream from White Rock Road, grid reference S27/17908825; a 50 mm thick, pinkish-cream tephra, almost completely degraded to clay with a small residue of corroded glass shards and in a massive blue-grey lacustrine siltstone. Correlatives are not known and the exposure is now covered by scree.

3. East bank of Huangarua River opposite Te Muna homestead, grid reference S27/18908945; paired tephras informally named Te Muna paired tephra beds, overlying a paleosol on lacustrine silt, and separated and overlain by loess. Glass chemistry of the lower tephra (by electron probe microanalysis; Mr. P. C. Froggatt, peTS. comm., 1981) resembles that of the Rewa Pumice Member of the Kaimatira Pumice Sand Formation in Wanganui Basin (glass fission-track age ofO. 74 ± 0.09 Myr; Seward, 1976).

4. Ridge south of Hinakura Road,S km northeast of Te Muna, grid reference S27/22709320; a poorly exposed, severely weathered, at least 100 mm thick greyish-white ash in brown-weathered siltstone, with conglomerate a few metres above and below. Correlatives are not known.

5. &6. Hinakura Road cutting at top of hill 1 km south-southeast of Popes Head Gunction of Longbush Road), 6.5 km northeast ofTe Muna, grid reference S27124459205; two tephra horizons each preserved in lignite-bearing silts (thought to be ox-bow lake deposits) in river channels cut into Te Muna gravels, with one channel partly superimposed on the other. The younger ox-bow lake deposit contains paired tephra beds informally named Popes Head tephra, with the upper bed having the same mafic mineralogy as the lower one and probably redeposited from the surrounding area. Blue-grey silt 0.5 m below the lower of these tephra beds has reversed magnetic polarity and is therefore considered to be older than 0.7 Myr. The older ox-bow deposit contains one tephra bed with different mafic mineralogy from the Popes Head tephra, and is informally named Akupe tephra. No correlative of either tephra horizon is known.

Age and Correlation None of the tephras in Te Muna Formation has the distinctive field characteristics

and mineralogy of the Mount Curl Tephra (which occurs in the younger Ahiaruhe Formation, described below). It is not known which if any of them at the several localities are correlatives of one another. At present they do little more than indicate a Castlecliffian

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age for the Te Muna Formation, although they do have the potential to provide more precise dating.

Paleomagnetism indicates a late Matuyama age for most of the formation below the Te Muna paired tephra beds, and less definitely suggests a Brunhes age for most of it above the Te Muna paired tephra beds. This is in good agreement with the suggested Rewa Pumice correlation of the tephra beds, which would indicate an age of O. 74 ± 0.09 Myr (Seward, 1976). The 366 m thickness ofTe Muna Formation indicates a considerable age range. The inferred slight unconformity with the Hautotara Formation in the centre of the Huangarua Syncline implies an age slightly less than 1.05 Myr for the base. It is reasonable to assume that the upper half of the formation (above Te Muna paired tephra beds) represents a similar amount of time to the lower half, so the top of the formation might be about 0.35 Myr or 0.4 Myr old.

Conditions of Deposition The Te Muna Formation is entirely non-calcareous. The only known fossils in it are

rare decalcified freshwater mussels (Hyridella), abundant wood, poorly preserved leaves (mostly reeds), and pollens and spores. At places the blue-grey silts have thin bands of light and dark grey, usually containing flecks of carbon, which we consider to be freshwater lake deposits. The lignitic horizons, often with tree roots in growth position (usually intercalated with the blue-grey silts) evidently represent intervals during which the lake waters shallowed to lake margin swamp conditions, allowing the growth of forest cover. The cross-bedded sands were deposited either in a river delta built out into a lake, or on a lake shore exposed to vigorous waves, as would be expected on the eastern side of a deep and wide lake in Wairarapa valley. The tangle of buried logs in cross-bedded sands in the Huangarua River bank just south of Te Muna could have been deposited in either environment, but to be preserved they must have been buried quickly, and that would be most likely to happen in a delta.

Throughout the formation, Te Muna conglomerate members display large-scale trough cross-bedding, and contain small lenses (up to 1 m thick by several metres long) of silt or sand. Clasts are mostly of pebble to cobble size, the average being distinctly smaller than in overlying late Quaternary terrace deposits. The lower conglomerate members (up to Member 5, Fig. 6) are better sorted and rounded than the upper ones. We consider that they were all deposited by rivers that were braided for most of the time and flowing over aggrading floodplains. Pebble imbrications at Popes Head and along Huangarua River indicate an average flow direction towards the southeast, suggesting a provenance in the direction of the Tararua Range, but clast sizes increase soutwards from Vvhite Rock Road, suggesting a provenance in the Aorangi Range. Perhaps two river systems flowed together near the present White Rock Road.

We interpret the alternations of eight alluvial aggradation gravel members with seven lacustrine and swamp silt deposits to represent sedimentary cycles related to climate and sea-level fluctuations. The alluvial aggradation deposits, like most of those of the late Quaternary, probably indicate deteriorating and harsh climates causing deforestation, high country erosion, high river bed loads, lowered sea-level and steep river gradients. The fact that all the pollen assemblages examined represent relatively warm-climate lowland forests can be explained because only the mild climate deposits were sampled (Fig. 6).

The fifteen (eight conglomerate and seven siltstone-sandstone) members of the formation form seven and a half sedimentary cycles. Milankovitch calculations predict that seven and a half major climatic cycles should occupy 0.75 Myr (Milankovitch, 1938; Hays et at., 1976), a period coinciding with our inferred age range of the Te Muna Formation.

The 366 m thickness of Te Muna Formation i~ the Huangarua Syncline indicates progressive tectonic subsidence during its deposition. At Popes Head the overlap of Te Muna Formation onto eroded Pukenui Limestone indicates a change from relatively high to low relief best attributed, in the context of Quaternary history, to a change from a low sea-level phase to a high sea-level phase; and subsidence evidently was much slower than in the Huangarua Syncline. The Huangarua Syncline was beginning to form at

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310 Journal of the- Royal Society of New Zealand,Volume 14, 1984

this time, and the Te Muna Formation in that area is largely confined to it. Elsewhere in Wairarapa, Te Muna Formation is probably similarly restricted to synclinal depressions that were forming at the time of its deposition. The synclines were still sinking relative to average sea-level, but the anticlines between were probably beginning to rise above average sea-level. The Te Muna Formation represents the time when vertical tectonic movement in Wairarapa Valley was changing from overall downdrop to overall uplift.

AHIARUHE FORMATION The type section, here designated, is the cutting on the east side of Ahiaruhe Road

2 km north of the junction with Ponatahi Road, grid reference S27127350955 to 27700985 (Fig. 10). The exposed section is 7 m thick and does not show the top or base of the formation. The upper 5 m of exposed section is rusty-stained gravel (Fig. 11) with moderately rounded pebbles (predominant) to cobbles of slightly weathered Mesozoic greywacke coated with red-brown to yellow-brown iron oxide.

Dvounger Alluvium

ft~fJAhiaruhe formation

1@~J]~1:\t:]~~:~U~I~~~:~~;)

• MeSOZOIc

~• Structural contours

':"rfJ .... :;-f. Ahlar~he Surface ..... .. at 20m. Intervals

1B Roads

Fig. lO-Geological map of Ahiaruhe Formation. Pre-Ahiaruhe geology and structure simplified for clarity.

The lowest two metres of exposed section consists of yellow-brown silt containing a band of white to brown-mottled tephra 0.25 m thick about 0.3 m below the top (Fig. 12), informally named Ahiaruhe tephra in manuscripts. Most of the tephra band is fine, white and glassy, but the basal few centimetres are slightly coarser-grained and crystal-rich with distinctively visible mafic minerals. We separated a sample of zircon crystals from the crystal-rich layer and sent them to Dr D. Seward for fission-track dating. The results will be reported elsewhere. Dr Seward (pers. (omm., 1982) reported that the size and abundance of the zircons is typical of Mount Curl Tephra (glass fission-track age of 0.23 ± 0.03 Myr; Milne, 1973). The whole mineral assemblage (Dr A. Palmer, pers. (omm., 1982) and the glass chemistry (by electron probe microanalysis; Froggatt, unpublished) are also typical of Mount Curl Tephra, and the field characteristics support this correlation.

Alluvial gravel reappears below the type section, but its thickness and the full thickness of the yellow-brown silt are unknown. The silt is water-laid but contains a substantial loessic component (Mr C. G. Vucetich and Dr A. Palmer, pers. (omms., 1981).

The thickness of the formation varies and generally decreases eastward. On the northeast

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Fig. 11 - Conglomerate of Ahiaruhe Formation at type locality, Ahiaruhe Road. Hammer length! 327 mm.

Fig. 12 - Mount Curl Tephra in siltstone of Ahiaruhe Formation at type locality, Ahiaruhe Road, underlying conglomerate of Fig. 11. Mafic layer visible at base of tephra, above hammer head. Hammer length 327 mm.

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Holocene Gravel Angular unconformity 80~ ~ 00- b 0 Rus~- brown, fine

) :0 0: ~:o 0: cong omerate

o 00 0 0

70~COVEflED

lignitic claystone 60 ...... Mount Curl Tephra Z

. - - -Orange- mottled, blue- grey 0

oooooOob I-siltstone «

50~ fi ne conglomerate ~ a::

COVERED 0 u...

~4°1 UJ .... I .... <IJ ::> E a::

30 . - _ -:-.:...-:- Greenish, blue-grey siltstone « . - I

<t COVERED

20t - -- . -

Greenish, blue-grey siltstone

10~ I

COVERED Blue-grey siltstone with angular greywacke clasts An I f'ty

O~~ 90 ar uncon orm.

Greeni sh - grey Mesozoi c grey wacke

Fig. 13 - Stratigraphic column of Ahiaruhe Formation, true left bank of Ruamahunga River near end of Foreman Jury Road.

side of Millars Road (Fig. 10) it tapers to a thickness of three metres of fairly strongly cemented gravel towards the northwest flank of Gladstone Anticline. There, a thin loess cover over the formation contains Kawakawa Tephra C4C age c. 0.02 Myr; Vucetich and Howorth, 1976).

In the true left bank of the Ruamahanga River bank near the end of the Foreman Jurie Road, 4.5 km west-southwest of the type locality, the Ahiaruhe Formation appears to contain a substantial thickness of water-laid silt. A section about 80 m thick is represented, but only about 25 percent of it is exposed (Fig. 13). The beds dip east at 30 0

, and unconformably overlie Mesozoic greywacke which is exposed in the river bank to the west and which forms most of the Jury ridge to the south (Fig. 10). Only about 2 m is exposed at the base; it consists of blue-grey silt containing numerous pebble-sized angular clasts of Mesozoic greywacke, resting on a flat unweathered surface of green-grey greywacke. Most of the section is covered between 2 m and 54 m above the base, but weakly compacted greenish blue-grey silt is exposed at 14 to 17 m and at 28 to 38 m. Between 54 and 62 m there is a sequence of fine rusty gravel, orange-mottled blue-grey siltstone, tephra with a silcrete layer within it (O'Brien, 1980), and finally lignitic brown mudstone. After a further covered interval, rusty-brown weakly cemented gravel is exposed between 73 and 82 m above the base, and is unconformably overlain by two to three metres of horizontal gravel that is probably Holocene in age. The greenish blue-grey siltstone is presumed to have been deposited in a lake, and appears to form nearly the whole of the lowest 50 m of the formation; however, that is not certain because the large covered intervals might conceal other facies. The tephra is 1 m thick and has the crystal-rich, relatively coarse layer at the base characteristic of Mount Curl Tephra. The

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Collen, Vella-Hautotara, Te Muna and Ahiaruhe Formations 313

mineralogy is also typical of Mount Curl Tephra, and biotite is visible in hand specimen. In 1980 a fresh caused a collapse of Ahiaruhe siltstone in the true left bank of

Ruamahunga River, 1 km east of the Mount Curl Tephra exposure at Foreman Jury Road (grid reference S27/243084), and exposed a footprint of a large moa. The footprint was reported by Mrs R. W. Watters and Mrs Y. Summers, but because of the softness of the siltstone and continuing rain, it was already blurred when discovered and could not be preserved. However, a photograph of it in the possession of Mrs Watters has been seen by Sir Charles Fleming, who confirmed the identification.

Relation to Underlying Rocks At various places the Ahiaruhe Formation unconformably overlies Mesozoic greywacke

and argillite, Bells Creek Mudstone (upper Miocene to lower Pliocene), Mangaopari Mudstone (Pliocene) and Pukenui Limestone (lower Pleistocene). It has not yet been shown to overlie Te Muna Formation, but the reason for that may be the difficulty of distinguishing between the two formations, both of which consist mainly of rusty-stained alluvial gravels and freshwater silts.

Fig. 14- View southeast from Ahiaruhe Road to Jury Ridge in distance. Ahiaruhe Formatio~ underlies Ahiaruhe Surface in foreground and middle distance, and laps onto Mesozoic greywacke of Jury Ridge at about slope break.

Ahiaruhe Surface The Ahiaruhe Surface (Figs. 14, 15) is a dissected and gently warped topographic feature

that was originally the nearly flat depositional surface at the top of the Ahiaruhe Formation. Large areas of it are still only gently tilted, not very high, relatively little dissected, and form terraces. Other parts of it are tilted at angles of up to 6 0

, raised high above the adjacent streams, and deeply dissected, so can no longer be regarded as terraces. The high proportion of it still preserved as terraces and terrace-like sloping landforms (Fig. 14) is one of the features that distinguishes Ahiaruhe Formation from Te Muna Formation, on which the original depositional surface is much less distinct.

The type surface is taken to be the top of the Ahiaruhe Formation at its type locality.

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Fig. 15 - Conglomerates and siltstone (light-coloured layer) of Ahiaruhe Formation in true left bank of Ruamahunga Rivcr by Carterton-Ponatahi Road bridge. Ground surface at top of cliff is Ahiaruhe Surface.

There, the Ahiaruhe Surface is deformed into a half dome with an elevation of 119 m at its crest (Spectacle Trig Station), on the northwest side of Popoiti Fault. On the southeast side of the fault it is displaced down about 60 m, and rises gradually towards the southeast at an angle of 1-2°. From the Popoiti Fault it dips at 2-3° northwest, and forms the top of cliffs gradually decreasing in height westward along the side of the Ruamahanga River between the Carterton-Ponatahi Road and the Foreman Jury Road (Fig. 15).

Distribution The Ahiaruhe Formation and Ahiaruhe Surface have been mapped as a nearly

continuous belt west of the Popoiti Fault, extending for 16 km between Ahiaruhe and the northeast side of the Huangarua River near Martinborough. Correlation is certain along this belt because of the continuity of the Ahiaruhe Surface heights from valley side to valley side. There is also little doubt about the correlation of the part mapped on the southeast side of the Popoiti Fault east of Ahiaruhe.

Similar deposits with similar topographic expression of the depositional surface at the top have been mapped as Ahiaruhe Formation at other places in Wairarapa Valley. The most extensive are rusty-stained gravels capping the Harris Trig Station Ridge crossed by White Rock Road 3 km south of Martinborough, and gravel interbedded with siltstone capping the Te Maire-Bidwell Ridge between Martinborough and Featherston. Both have loess cover beds which we interpret as three-layered and representing the three stadials of the Last Glaciation. Consequently, the underlying gravel and silt have been considered to represent the Last Interglacial Stage (c. 0.1 to 0.2 Myr in age; Ghani, 1974). No tephra has been found in the gravel and silt, but that means little because exposures are rare. Tectonic deformation is similar to or greater than that of the Ahiaruhe Formation at its type locality. Harris Ridge is the upthrown (northwest) side of the active Dry River Fault, and its capping deposits dip northwest at up to 6 0. The surface on Te Maire-Bidwill Ridge is strongly warped and is vertically displaced, locally up to 40 m, by the Te Maire Fault. The amount of deformation seems greater than might be expected in

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0.1 Myr, but more information on tectonic rates is needed. It is possible that pre-Last Glaciation loesses were stripped off the surfaces by erosion before the start of the Last Glaciation.

Environment of Deposition The gravels of Ahiaruhe Formation were deposited by aggrading rivers. As the lower

part passes laterally westward into lacustrine siltstone at Foreman Jury Road, we presume, by analogy with the present Lake Wairarapa, that it was deposited during a high sea-level (i. e., interglacial or interstadial) phase. The presumed 50 m thickness of lake silt at Foreman Jury Road suggests that the lake started as a deep body of water, not small and localised but perhaps extending across the whole or most of the lower part of Wairarapa Valley. It implies a sea-level rise of 50 m or more, such as would result from a major climatic amelioration.

Eastward thinning of the formation implies tectonic tilting while the formation was being deposited.

Age and Correlation The presence of Mount Curl Tephra indicates an age greater than 0.2 Myr for the

base and less than 0.26 Myr for the top of Ahiaruhe Formation at its type locality and at Foreman Jury Road; and an age between 0.2 and 0.26 Myr for the tephra horizon itself. If the formation was deposited during an interglacial interval, it must have been the Penultimate Interglacial Stage. The ocean water oxygen isotope record (Hayes et at., 1976) shows two pulses in the Penultimate Interglacial, a lesser peak at about 0.24 Myr and a major peak at about 0.2 Myr B.P. According to the tephrochronology the Ahiaruhe Formation could represent either or both of these two interglacial peaks. The stratigraphy of the formation is not well enough known to show whether the intra-interglacial cold interval at 0.225 Myr is represented.

The possibility exists that some strata in Wairarapa that we mapped as Ahiaruhe Formation are as young as the Last Interglacial Stage.

CONCL USIONS The Hautotara Formation represents the last incursion of sea into the eastern part

of Wairarapa Valley, recording a rapid transition, just over a million years ago, from a large fully marine embayment to a land area that was intermittently flooded by freshwater lakes. The regression of the sea was caused not by tectonic uplift but by the rate of tectonic subsidence failing to balance the rate of sediment deposition in the pre-existing marine environment. In the Huangarua Syncline, subsidence continued at least until the end of deposition of the Te Muna Formation about 350,000-400,000 years ago. The Te Muna deposits are very like most late Quaternary deposits of the southern North Island, and we interpret them here in terms of climatic changes, in the same way as is done for the late Quaternary. For example, the loess deposits that cover and preserve the Te Muna Tephra are completely analogous with those of the late Quaternary loess deposits, although they might be the oldest surviving loesses in New Zealand. The only significant difference is that the Te Muna deposits are stacked in conformable sequence, whereas late Quaternary deposits tend to be isolated on individual terraces. This is the difference between deposits that accumulated in a tectonic regime of subsidence and those that accumulated in a tectonic regime of uplift.

The increasing proportion of gravel to silt towards the top of Te Muna Formation suggests increasing relief of the gravel sources, the most important of which were probably the Aorangi and Tararua ranges. Both were emergent probably throughout the late Miocene and Pliocene (Vella and Briggs, 1971), and must have been areas of continuous uplift. Conglomerates in the upper part ofPukenui Limestone (Vella and Briggs, 1971), Hautotara Formation, and the lower part of Te Muna Formation might reflect only temporary increases in relief caused by glacio-eustatic falls of sea-level. Consequently, it is difficult to pinpoint the time when the present phase of rapid tectonic uplift of the mountains commenced; however, it was probably some time during the deposition of

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the Te Muna Formation, between one million and four hundred thousand years ago. During Te Muna time the zero isobase, which is now mainly offshore in Palliser Bay (Ghani, 1974, 1978), lay to the east of the easternmost outcrop of Te Muna Formation (at Popes Head) and may have extended northward as far as Masterton. The pattern of deposition undoubtedly was complicated by growing anticlines in Wairarapa Valley, as shown by the strong angular unconformity between Hautotara and Te Muna formations in the steeply dipping northwest flank of the Huangarua Syncline.

The Ahiaruhe Formation is mostly a terrace deposit of the sort formed in a tectonic uplift regime. It appears to be analogous with present Holocene deposits of Wairarapa Valley, which have a flat and very gently sloping upper surface and consist of alluvial gravels, sands and silt~ passing laterally into the silts being depos;ted in Lake Wairarapa. Dune sands like those that interrupt the flatness of the Holocene surface on the eastern (lee) side of the present lake have not been recognised on the Ahiaruhe Surface.

The Hautotara, Te Muna and Ahiaruhe formations together represent probably 80 percent or more of the time between 1.2 Myr B.P. and 0.2 Myr B.P., and contain evidence of nine high sea-level phases-the same number inferred to have occurred within that amount of Quaternary time by the Milankovitch calculations. The palynological samples so far examined from Te Muna Formation all indicate lowland rain forest vegetation, and give no evidence of climatic variations; but that is to be expected, because all samples were from lake deposits which are presumed to represent high sea-level and hence interglacial phases. Silt lenses in the gravel members of the Te Muna Formation might yield cooler climate palynofloras.

ACKNOWLEDGEMENTS This study was carried out by a geological mapping group of the Wairarapa

Geological Society. Other regular participants were E. Bannister, J. Hawkins, R. Jane, V. Johnston, R. Lumsden, R. McKendry, K. McLeod, B. Mercer, G. Monk, G. Miller,J. Nalder, C. O'Brien, E. Smith, G. Suckling, Y. Summers, A. Thomson and D. Toole. We thank Mr A. D. McLeod at Mangaopari, the late Mr G. S. McLeod and his sons at Hautotara, Mr 1. A. Campbell at Te Muna, and other farmers too many to name but always helpful and co-operative. Mrs Y. Summers undertook much of the organisation of the project, and many members of the Wairarapa Geological Society, other than those mentioned above, have participated from time to time in this study. Undergraduate students from Victoria University of Wellington have contributed information that we have not acknowledged in the text. Mr E. F. Hardy drafted the maps and diagrams, and Ms V. Hibbert typed the manuscript.

This study was initially sponsored by the Victoria University Department of University Extension, and has been supported throughout by the Internal Research Committee of Victoria University of Wellington.

REFERENCES Bates, T. E., 1967. The geology oj the Northern Aorangi Range and part oj Palliser Bay Sheet N165.

Unpublished M.Sc. thesis, Victoria University, Wellington. Bloom, A., Broecker, W. S., Chappell, J., Matthews, R. K., and Mesolella, K. J.,

1974. Quaternary sea level fluctuations on a tectonic coast: new 230ThP34U dates from the Huon Peninsula, New Guinea. Quaternary Research 4: 185-205.

Fleming, C. A., 1953. Geology of the Wanganui Subdivision. N.Z. Geological Survey Bulletin n.s. 52.

Ghani, M. A., 1974. Late Cenozoic vertical crustal movements in the central part oj New Zealand. Unpublished Ph.D. thesis, Victoria University, Wellington.

1978. Late Cenozoic vertical crustal movements in the southern North Island, New Zealand. N.z. Journal oj Geology and Geophysics 21: 117-126.

Hayes,J. D., Imbrie, J., and Shackleton, N.J., 1976. Variations in the earth's orbit: pacemaker of the ice ages. Science 194: 1121-1132.

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Hector,]. 1884. Progress report, 1884. NZ. Geological Survey Report oj Geological Explorations during 1883-84: IX-XXXVIII.

Kennett, J. P., 1964. A Pleistocene anticline at Gladstone, Wairarapa. N.z. Journal oj Geology and Geophysics 7: 561-572.

Kennett,]. P., Watkins, N. D. and Vella, P., 1971. Paleomagnetic chronology of Pliocene-early Pleistocene climates and the Plio-Pleistocene boundarY;T) New Zealand. Science 171: 276-279.

Lensen, G. ]., and Vella, P. 1971. The Waiohine River faulted terrace sequence. In B. W. Collins and R. Fraser (Eds.): Recent Crustal Movements, pp. 117-119. Royal SOClety oj NZ. Bulletin 9.

Lillie, A. R., 1953. The Geology of the Dannevirke Subdivision. NZ. Geological Survey Bulletin n.s. 46.

MacKay, A., 1879. Report on the east Wairarapa district. NZ. Geological Survey reports oj Geological Explorations 1877-1878 II: 14-23.

Mesolella, K. ]., Matthews, R. K., Broecker, W. S. and Thurber, D. L, 1969. The astronomical theory of climatic change: Barbados data. Journal oj Geology 77: 250-274.

Milankovitch, M., 1938. Astronomische Mittel Zur Erforschung der Erdgeschichtlichen Klimate. Handbuch der Geophysik. 9: 593-698.

Milne,]. D. G., 1973. Mount Curl Tephra, a 230,000-year-old marker bed in New Zealand, and its implications for Quaternary chronology. NZ. Journal oj Geology and Geophysics 16: 519-532.

O'Brien, C. M., tephras, eastern Wellington.

1980. The stratigraphy, petrography and glass chemistry oj some mZd to late Pleistocene Wairarapa. Unpublished B.Sc. Honours dissertation, Victoria University,

Rodley, D., 1961. and Makara rivers.

The geology and paleocology oj Nukumaruan strata near the JunctZon oj Ruakokopatuna Unpublished M.Sc. thesis, Victoria University, Wellington.

Seward, D., 1974. Age of New Zealand Pleistocene Substages by fission-track dating of glass shards from tephra horizons. Earth and Planetary Science Letters 24: 242-248.

1976. Tephrostratigraphy of the marine sediments in the Wanganui Basin, New Zealand. N Z. Journal oj Geology and Geophysics 19: 9-20.

1979. Comparison of zircon and glass fission-track ages from tephra horizons. Geology 7: 479-482.

Thomson, A. B., 1980. The structure, stratigraphy and paleontology oj late Cenozoic strata, Blue Rock Stream, Wairarapa. Unpublished. B.Sc. Honours dissertation, Victoria University, Wellington.

Vella, P., 1963. Plio-Pleistocene cyclothems, Wairarapa, New Zealand. Transactions oj the Royal Society oj NZ., Geology 2: 15-50.

Vella, P., and Briggs, W. M., 1971. Lithostratigraphic names, Upper Miocene to Lower Pleistocene, northen Aorangi Range, Wairarapa. N Z. Journal oj Geology and Geophysics 14: 253-274.

Vucetich, C. G., and Howorth, R., 1976. Proposed definition of the Kawakawa Tephra, the c. 20,000-years-B.p. marker horizon in the New Zealand region. NZ. Journal oj Geology and Geophysics 19: 43-50,

Received 29 April 1983; accepted 20 January, 1984.

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Download - Hautotara, Te Muna and Ahiaruhe Formations, middle to late Pleistocene, Wairarapa, New Zealand

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