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The Tertiary geology ofthe Pareora district, SouthCanterburyH. S. Gair aa Department of Scientific and Industrial Research ,New Zealand Geological Survey , New ZealandPublished online: 21 Dec 2011.

To cite this article: H. S. Gair (1959) The Tertiary geology of the Pareora district,South Canterbury, New Zealand Journal of Geology and Geophysics, 2:2, 265-296, DOI:10.1080/00288306.1959.10417648

To link to this article: http://dx.doi.org/10.1080/00288306.1959.10417648

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THE TERTIARY GEOLOGY OF THE PAREORADISTRICT, SOUTH CANTERBURY

265

By H. S. GAIR, New Zealand Geological Survey, Department ofScientific and Industrial Research

(Received for publication, 7 October 1958)

Summary

The marine Tertiary rocks in the Pareora district are about 1,500 ft thick andrange in age from ?upper Dannevirke Series to Awamoan. They are underlainand overlain conformably by two sets of coal-measures, each about 200 ft thick,but only the lower contains potentially workable lignite seams. The uppercoal-measures of probable Southland age are overlain disconformably or withslight angular unconformity by 600 ft of non-marine, weathered, greywacke gravels(of probable Waitotaran age) which have been folded and faulted together withthe underlying Tertiary rocks. These tilted gravels are overlain unconformablybv flat-lying, high-level gravels of Pleistocene age .. The Tertiary rocks are in fault contact with the greywacke and argillite of

the Hunters Hills' on the west, the fault having a throw of about 4,000 ft. Thelittle evidence available suggests that this is a reverse fault Between the HuntersHills and the sea the Tertiary rocks have been folded into an asymmetrical anti­cline of which the steep western limb passes into a fault to the north.

I t is suggested that, because the Waitotaran gravels were deposited while theKaikoura Orogeny was in progress, they are thickest over the structurallows and thinnest over the structural highs, and that, depending on the amountoi erosion prior to their deposition, they may overlie any of the Tertiary forma­tions and possibly even the grey wacke undermass.

PREVIOCS GEOLOGICAL IKVESTIGATIOKS

The area described lies to the east of the Hunters Hills, and betweenthe Pareora and Otaio rivers (Fig. 1).

Many geologists have visited and written about the area, hut onlyone detailed survey, that of Cudex (1918), has been carried out.

The first geologist to visit the district was W. Mantell (1850) whotraversed the coastal part on his journey from Christchurch to Dunedinin 1848. He mentioned the presence of a vesicular volcanic rock atTimaru and stated that he was informed that a heel of coal, ten feetthick, cropped out on the banks of a stream inland of Tirnaru.

Haast (1865) examined the country between 1\1 t. Horrible andTirnaru, and the banks of the Pareora River, with a view to obtaininga water supply for T'imaru, He correlated the Tertiary sequence withthe Curiosity Shop beds, and stated that there were several flows ofbasalt some of which were intercalated with the marine beds. In his"Geology of Canterbury and Westland", Haast includes a cross-sectionfrom the Hunters Hills across the Upper Pareora basin to the coast.

NX J. c-»: Croph.1's. 2 : 205-90,

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266 N.Z. JOURNAL OF GF;OLOGY AND GEOPHYS1CS [MAY

N

t

Christchurch

100!

Scale50

!a

!

Timaru

"- Locality of AreaDiscussed in this Paper

50!

FIr;. I.-Locality map.

McKay (1877) described the succession and drew a section fromnorth-west to south-east.

Park (1905) considered the sections at the lower and upper ends ofthe Pareora Gorge as too obscure to be of value for determination ofthe relations between the beds containing the "Pareora Fauna" and theOamaru limestone, and stated that the fossiliferous clays and sandstonesexposed at White Rock River rest on the basement rock of the district.

Hardcastle (1908) published a booklet on the geology of SouthCanterbury, in which the stratigraphy of the Tertiary rocks was dealtwith from the point of view of climate. He held that the gravelsbeneath the M]. Horrible basalt represented an earlier glacial age thanthe loess which overlies the basalt.

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Thomson (1914) concluded that in South Canterbury and Otagothere arc not two limestones separated by beds with the "PareoraFauna" as Park in 1905 supposed, but one limestone separating twosets of beds with the "Pareora Fauna", and suggested that these twosimilar faunas must show some difference when carefully examined.

Marshall (1916) described a specimen of the lower argillaceous lime­stone of the Otaio Gorge, and, arguing from the presence in it ofAmphistegina, correlated it with the Amuri Limestone. Thomson in1917 disputed this correlation, firstly on the grounds that Am.phisteqina,on Marshall's own showing, ranges from Upper Eocene to the present,and secondly, on the' grounds that the Otaio Limestone overlies rocks'with an Oamaruian fauna, while the Amuri Limestone everywhere over­lies rocks with a Cretaceous fauna and contains a lower Oamaruianfauna in its uppermost part, as in the Castle Hill basin.

Gudex (1918) made a detailed survey of the area between thePareora and' Oraio rivers more from the point of view of the strati­graphy than of the structure and geomorphology. He summarized his con­clusions as follows: "My examination of the district shows that theTertiary beds of the district are all conformable, and not separable intotwo unconformable groups as McKay supposed; that the upper beds'with a 'Pareora Fauna' are above the limestone, and not below it asPark supposed; and that there is a similar fauna above and below thelimestone, as Thomson suggested. I agree further with Thomson thatthe lower chalkv limestone of the Otaio River is not the correlativeof the Amuri I .imestone, but represents a higher horizon."

Thomson (1926) observed in the lower Pareora Gorge a phosphaticcontact between a glauconitic limestone above and a chalky limestonebelow. He described the bored surface between these beds as similarto that between the Weka Pass and the Amuri Limestones and thoughtit probable that the phosphatic horizons in the Waihao, Pareora, andTotara-Raincliff districts represented the same horizon.

Laws (1933) described new Tertiary Mollusca from the Timaru dis­trict and correlated the White Rock River and Holme Station faunaswith that at Sutherlands, which he considered to be of Awamoan age.

Maling (1933) compared the Tertiary sequences in the Kakahu andPareora districts and found them to he very similar save for the absenceof the blue clays. which were not recognized in the Kakahu district.

Finlay and Marwick (1947), in their paper on new divisions ofthe Upper Cretaceous and Tertiary, inserted, as a new division of theTertiary, an Otaian stage based on the blue silts in the Otaio River atBluecliffs. They defined the stratigraphic limits of this stage on bothForaminifera and Mollusca.

Ulrich (1947) made a geomorphic study of the Pareora River. Thepresence of Tertairy rocks in Mt. Nessing basin was mentioned, andthis landform was recognized as a tectonic basin. Mt. N essing was de­scribed as a tilted block and evidence for the presence of a fault at theUpper Pareora Gorge was presented.

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ThiCkness NEW ZEALAND NEW ZEALANDFORMATION LITHOLOGY in

STAGE SERIESAGE

Fed

loess LLLLLL eo- ~Sliqhtly weathered qreywocke graveh en d "" "" ....... U

Moungoti Groveh 00> HAWERA AND 0subordinate 1mS and lands --- t;;

/\/\/\UPPER WANGANUI

~Basalt 7S/\/\/\ Duconfcrmttv or iIi ht--0_ angular unconformity------- ----Predominantly we c t her ed qfQ,ywocke

o __

~Canninqlon Graveh grovels with sub cr dtnc f e sonds cnd lilts P bOO+ Woitotoron WANGANUI U

~Qa:--------- 0

:i----Disconformiry or Sliqht~-.;;-o:

~angular unconformity Z

0 TO UWhite Rock - --- ?TARANAKI u--- --

"Lignites, cloYl,quartz HIndI ond silts 1----- 200+Coal- memur e s

(~~~=SOUTHlAI\lU

= =CoorHl rncrme londs ond concretionory

p <=;

Awomoon

$ouHll.vrn Sand sanddon12S Abundant rncc r o-f o snls = bOO Hu t chlns cnion

'" places .'= (upper limit of Awomoon

unknown owing to the

=. tromition to non-

marine beds}~'.~

PAIHORAzu- -- 0- - -- O!- --- --- 0- ------

Fine-grained sandy ~i1t with regularly - --- - -----Bluecliffs Silt spaced hard silry sandi tone layers. - ---- --

Abundant mac::ro-fol~ils on plaC::lls -- --- --- - ---- ---- --- - 420 Or cto n--- ------ --- --Cr ctqmcre Ltmesrcre A,••o«o", ,lo"'o'iT" ..mi.'''''Oll~

ltmesrcne. Few mauo-fouils.

Squires GreensandCctccreous 910",0"," rend. ~

~Ric::~ br cchtopod fauno in places. 110 WoitoJc.ion

<, LANDONHolme Station ArgiJIoceOlu impure limestone 10 Duntroomcn

limestone No rncerc-fcs sus I-rl-r-'-r 30 Whalnqaroon

- -Sandy silts with irrequlorly spaced hard '-- --

littl. Porecrc Silt -'- .:...scndsone layers. Few macro-fossils. - ---- 250 ARNOLD---

Otcic Gorge CO",,,Tio.o,, ,;It, ,o.d, end ~~--'---'- 3Sandstone conglomeratic (quorh pebble) fOllilif~rousUseedstcees, .:;:::l. <:=." 30 3

~Colliers Coof-me<uureS

lignites. c1ay~. quartz seeds end quartz Co~:~':200

DANNEVIRKEpebble conglom.ratel. ~

:.:.;~~:;.Marked onquh;n-

~unconformity

? PERMIANHokonui Group Gre)'waCke and' argillite

Vertical Score

100... ---- o 100 200 300 reel

FIG. 2(a).-Composite Stratigraphic Column for the Pareora District.

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Feet

5000

-----

GAIR-PAREORA DISTRICT

Stage I

269

TARANAKI (Miocene)

-5000 L.L_L_-L~-L~-L..lL_L_.L_.L._L-_L-_...L_...L_...L_...L_..L_..L-...:.LJ

Stage n

a

EARLY WANGANUI

(Earl,! Pltcc ene]

-5000 L..L....._L....._-L__L....._L.....lL._L.....~"-~'--~"-_L-_L-......L_L....._L....._L....._L-_L_--L...

Stage ill

a

LATE WANGANUI

(Early Pleistocene)

Bcsott.{ Sheet

-5000 L_-L_~"-_L-_L-..L--'~....L.._..L_L--L_....L.._..L...L._L----'-~-L_..ILL...---'-_..LJ

Stage 17

HUNTERS HILLSBLOCK

PRESENT

5000

a

-5000 L.~'-_L-_L....._L....._L.....lL._L-~"--L_-.L_...L_.L._.LiL-_L....._L....._L......E"L-~'--...J

Sccle

a- .....[2Jr::::::::==lL===.J

Gr ejwccke and c rctlltte unde rmos s

Marine Tertiory, and Colliers and White Rock Cocl-mecsures

Conning ton Cr oveh

.-/ foult

NOTE: A Southland age is assumed for the White Rock Cool-measures

FIG. 2(b) .-East-west diagrammatic sections across the Pareora District in Post­Southland time.

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270 N.Z. JOUR.KAL OF GEOLOGY & GEOPHYSICS [MAY

Raeside (1948) discussed recent changes of climate in South Canter­bury and showed that the most recent change was from a warmpluvial to a cooler and drier climate.

STRATIGRAPHY

Pre-Tertiary Racl:»

These consist of greywacke and argillite with minor associated hedsof conglomerate and quartzite. The greywacke, and less commonly theargillite, are seamed with anastomosing quartz veins up to a few inchesin thickness. In the rivers draining the Hunters Hills a few pebblesof jasper and a calcareous siltstone occur and low rank schistose rocksare exposed in the Otaio and Lower Pareora gorges.

In three localities Tertiary rocks rest upon a residual clay up to7 ft thick which is the result of kaolinisation of the feldspar in thegreywacke. At Mt. Nessing, the feldspars have not been completelykaolinised, and the greywacke, although softened almost to clay has notlost its blue colour. At Maungati in both north and south hranches ofthe Little Pareora River, and in the north branch of the Little Pareoraat the foot of the Hunters Hills, kaolinisation is more complete andthe greywacke has been altered to soft white sandy clay.

The clays deri vcd from kaolinised greywacke can usually be dis­tinguished from those of the overlying coal formation by the presencein the fanner of! occasional quartz veins.

T ertiar3' Sequence

As is usual, the Tertiary rocks overlie the greywacke and argilliteundermass with marked angular unconformity.

In the composite stratigraphic column for this area (Fig. 2 (a)) it willbe noted that the writer has distinguished two formations additionalto those of Gudex (1918)-an upper coal formation, and a thicksequence of tilted greywacke gravels and silts. The latter is similar inoccurrence and character to the Kawai Gravels of North Canterburyand is probably its correlative.

The sequence represents a marine transgression and, regression dueto depression and subsequent upli ft of the area, and at only one contactis there any indication of a break in deposition of the marine beds. Thisis the bored surface between the argillaceous limestone and the cal­careous greensand, and may 110t represent a significant time interval.

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(1) COLLIERS COAL-MEASURES

Type Locality: Otaio River Gorge. Sheet S 118.

Grid Ref. 504365.

In most localities the lowest bed of this formation is a white plastic­clay up to 5 ft thick. This is overlain by a succession of white andblack (carbonaceous-stained) quartz sands, quartz-pebble gravels andconglomerates (mostly well-rounded hut some angular), grits, clays,and micaceous shales up to the first coal seam which is about SO to 70 ftfrom the base. Pyritic concretions are common in the beds beneath thecoal seams and are particularly abundant in some of the clays. Thecoal appears to be best developed along the base of the Hunters Hills,where as many as ten seams have been observed-elsewhere it is repre­sented by thin carbonaceous layers, as at Maungati. The coal is of ligniterank and is in seams up to 5 ft thick (but mostly less than 1 ft) which areinterbedded with quartz grits and sands stained by iron and carbonaceousmaterial. Above the lignites are about 100 ft of unconsolidated quartzsands, and a few quartz pebble conglomerates and gravels pre­dominantly 'white in colour. No marine fossils were obtained fromthese beds and it is concluded that they are all continental deposits.

(2) OTAIO GORGE SANDSTONE

Type Locality: Otaio River Gorge. Sheet S 118.

Grid Ref. 505366.

The coal formation is overlain bv rust-brown coloured, current­bedded, fossiliferous, silty sands that contain sandstone concretionsup to 5 ft in diameter, and cemented conglomeratic (rounded quartzpebbles about ~ in. in diameter) concretionary layers up to 3 ft thick.The concretionary layers contain abundant molluscan faunas whichDr ]. Marwick (pel's. c0111m.) has tentatively classed as upper Danne­virke Series. There is a good exposure of these hard, conglomeraticconcretionary layers about 300 yards downstream from the junctionof the north and south branches of the Little Pareora River at Maungati.

(3) LITTLE PAREORA SILT

Type Locality: Little Pareora River, Maungati.

Sheet S 110. Grid Ref. 536444.

Although Gudex, (1918) refers to this formation as "the crab-bedsand marls" the writer found only one fossil crab and was unable todistinguish the upper members as marls. In a few places difficulty isexperienced in separating hard sandstone layers near the base of theLittle Pareora Silt from similar beds in the underlying concretionarysands and conglomerates: the presence of layers of simple coralst Balanoph.yllia hectori Tenison-Woods ) in such sandstones places themwith the Little Pareora Silt.

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The formation consists predominantly of blue-grey sandy silts withirregularly distributed hard sandstone bands commonly 1 ft thick.These beds weather to rust brown colours. Small, hard, rounded,argillite pebbles about )'10 in. in diameter occur sparingly throughoutbut are more common in the top half of the formation. In general thel.ccls become less sandy towards the top where they grade into theHolme Station Limestone. Some' parts of the middle and upper mem­bers are moderately glauconitic, and the middle portion contains gypsumin small discontinuous films mostly at right-angles to the bedding planes.Fossil resin is common both in: this formation and in the underlyingOtaio Gorge Sandstone. No micro-faunas were obtained and theMollusca were in such a poor state of preservation that collecting wasnot attempted.

(6) CRAIGMORE LBIESTONE

(5) SQUIRES GREENSMm

(4) HOLME STATION LIMESTONE

I Type Locality:

~D. Squire's farm.j Sheet S 118. Grid Ref. 496376.

The occurrence of an upper arenaceous glauconitic semi-crystallinelimestone, separated by an impersistent layer of calcareous glauconitesand from a lower argillaceous almost chalky limestone with a bored sur­face and is typical of much of Canterbury (see Fig. 3). The upper aren­aceous limestone in the Pareora District (Craigrnore Limestone) isalmost identical in appearance with the Wcka Pass Stone of NorthCanterbury, and the lower argillaceous limestone (Holme Station Lime­stone) very closely resembles the Amuri Limestone of the MiddleWaipara District. Samples of the Craigmore Limestone from a limequarry on Frenchman's Gully road ranged from 80·2% CaCO., to93·75% CaCO", and samples of the Holme Station Limestone from thelower Pareora Gorge contained 63·5 % CaCO J anel 58% CaCO, respec­tively. The lower argillaceous limestone is massive, with the typical sub­conchoidal fracture of mudstone, and the upper part is slightly glauconitic, the grains of glauconite being much smaller than in the overlyingglauconite sand and semi-crystalline limestone. The depth of the boredzone varies from 6 in. to 3 ft and the borings arc filled with the over­lying calcareous glauconite sand (Squires Greensand). The latter variesconsiderably in glauconite content and hence in colour. In places thegreensand consists of mostly unconsolidated, current -bedded, glauconitesand, but usually it is 1110re calcareous than glauconitic and there is aprogressive increase in hardness with increase of calcium carbonate,About 6 in. to 12 in. above the base of the greensand is a single layerof phosphatic nodules up to 9 in. across, but 1110St commonly only ~ to1 in. in diameter. Usually the nodules appear as a line of small pebblesprojecting from the surface of the greensand, and in places they areso abundant that they form an almost continuous layer. By a gradualincrease in calcium carbonate content the greensand merges imper­ceptibly with the overlying semi-crystalline glauconitic limestone (Craig­more Limestone). This limestone is mostly regularly stratifiecl in hard

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FIG. 3.-Craigmore Limestone (A), Squires Greensand (B), and Holme StationLimestone (C). (D. Squires' farm.)

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274 N.L. JOURNAL OF GEOLOGY AND GEOPHYSICS IMAY

and soft layers, which give it a fluted surface on weathering. Thelower half of the limestone is current-bedded on a small scale. Thelowest twenty or so feet in most places is unstratified and in the middleportion hard bands arc spaced 9 in. to 1 ft apart, becoming further aparttowards the top of the limestone.

FAUNAS: Holme Station Limestone contains no macrofossils, but goodforaminiferal faunas of Whaingaroan age were obtained.

Squires Greensand contains a rich brachiopod fauna (the typicalLiothyrclla landonensis fauna) together with Pecten occasional Echino­derm spines and shark teeth, and fair Foraminifera faunas, all of whichindicate a Dunrtoonian age.

Craigmore Limestone contains Echinoderm fragments, Pecten, andshark teeth, and typical micro faunas of Waitakian age. The changefrom Waitakian to Otaian faunas occurs within the lowermost few feetof the overlying Bluecliffs Silt.

(7) BLUECLIFFS SILT

Type Locality: Bluecliffs, Otaio River.

Sheet S 111. Grid Ref. 575404.The arenaceous semi-crystalline limestone passes gradually up into

a blue sandy silt ("Blue clay" of Gudex) in which hard sandstonelayers 5 ft to 6 it apart and about 1 ft thick give a very regularlybanded appearance. The silt is fossiliferous throughout, but more soin the middle and upper portions, the macrofossils being chiefly Mol­lusca with a few brachiopods ncar the base. Pyritic concretions occurirregularly throughout, and gypsum in small films is widely distri­buted. This formation constitutes the Otaian stage.

(8) SOUTHBURN SAND

Type Locality: Southburn Cutting, Otaio River.Sheet S 119. Grid Ref. 597393.

The Bluecliffs Silt grades up into brown-coloured sands anti sand­stones, first by a change of colour from a blue-grey to a brown silt,then a textural change from silt tel sand. Sandstone layers, commonly2 ft thick and spaced about 5 to 10 ft apart, and concretions up to5 ft in diameter, occur throughout almost the whole of the SouthburnSand. \N ell preserved Mollusca occur in profusion in or adjacent tothe sandstone layers and concretions. These and Foraminifera date theformation as ranging in age from Hutchinsonian to Awamoan.

(9) WUITE ROCK COAL-MEASURES

Type Locality: vVhite Rock River.

Sheet S 110. Grid Hd. 490553.

The White Rock Coal-measures and the overlying Cannington Gravelstogether constitute the Pareora Gravels as defined originally by McKay(1882, p. 100) and Hector (1882, p. 25).

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White Rock River and the Pareora River about three miles belowthe upper gorge are the only localities where this upper coal formationis exposed. Only one shaly lignite seam and about 40 ft of white andgrey quartz sands are exposed in the Pareora River, where there ap­pears to be a greater disconformity with the overlying CanningtonGravels, but at White Rock River some i mile upstream from itsjunction with the Pareora at least 200 ft of the upper coal formationis exposed. There, the underlying Southburn Sand grades upwards intoblack (carbonaceous-stained) quartz sand which in turn is overlain bytwo 4 ft lignite seams separated by a 4 ft bed of carbonaceous shale.Veins of gypsum up to ! in. thick occur throughout the lignite, par­ticularly along bedding planes. The lignites are exposed again in asmall syncline about 3 miles farther upstream. The lignites, clays, andshales of the coal-measures are overlain by several hundred feet ofsands, silts, and greywacke conglomerates of the Cannington Gravelsand the dip increases from 27° at the lignites to 67° at the top of theCannington Gravels. The clays and shales associated with the coalformation range in colour from blue to grey-white and thus can bedistinguished from the predominantly yellow-coloured clays of theoverlying Cannington Gravels. Plant microfossils from the White RockRiver section indicate a Southland age for the White Rock Coal­measures.

(10) CANNINGTON GRAVELS

Type Locality: Left bank, Pareora River, Cannington.

Sheet S 110. Grid Ref. The terrace extendingfrom 468598 to 510569.

Overlying either the White Rock Coal-measures or the SouthburnSand, disconformably or with slight angular unconformity, is a suc­cession of non -ruarine, weathered greywacke gravels, silts, and claysthat have been faulted together with the underlying Tertiary beds,They are particularly well developed at Cannington, which is theirtype locality, and are exposed also at White Rock River, Maungati,and south-west of Maungati to the west of the Maungati Fault. Inthe type locality the Cannington Gravels constitute the high plateauwhich forms the northern boundary of Cannington basin, and goodexposures occur in the badland gullys along the southern edge of thisplateau overlooking Cannington basin (see Fig. 4). The gravels havebeen folded into a gentle syncline (clips of up to 10°) at the westernlimb of which they overlie about 15 ft of White Rock Coal-measures.

At Maungati the Cannington Gravels occur in an asymmetrical syn­cline, the steep eastern limb of which (dip 60°-sec Figs 5 and 6)has been faulted against Colliers Coal-measures overlying greywacke.In south-west Maungati the Cannington Gravels are exposed at severalplaces along Cabbage Tree Point road, and in a road-cutting about 300

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27G 1\.Z. jOUR:-.iAL OF GEOLOGY AND GEOPHYSICS L:-Lw

FIG. 4.-Cannington Gravels. type locality, Cannington. Note the slight dipupstream (to the left).

yards from the junction of! this road with the road on the north sideof the Otaio River. is an exposure of very weathered, steeply dippingCannington gravel a11(1 silt overlying fossili ferous Southhurn Sand.The Canning-ton Gravels can he distinguished from younger gravelsby the following criteria:

(1) They are usually (but not necessarily) inclined. In the absenceof other evidence. gravels and silts dipping upstream (how­ever slightly) are likely to he Cannington Gravels.

(2) The greywacke pehhles arc on the whole considerably we-atheredand many can be crushed hy hand.

(3) Thcv are usually more cemented, mostly bv iron oxides, andh~nc~ are conunonlv rust-red in colou;. -

(4) They contain more silt and sand layers than do younger beds,particularly in the lower anel middle portions.

(5) A few of the silts and silty clays contain fragmentary plantremains which have not been found in Plcistoccuc and Recentgravels.

ACE: The discovery by :VIr J. D. Raeside in 1946 (Collins, 1953) of\Vaitotaran marine fossils in weathered greywacke gravels, of similaroccurrence and character to the Cunnington Gravels. in the MakikihiRi vcr about 9 miles south of the l'areora District. strongly suggeststhat the Cannington Gravels are also of Waitotaran age and thusthe correlative of the Kawai Gravels of X orth Canterbury.

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FlG. 5.-Canllington Gravels dipping at about (lO'. South branch of tile LittlePareora River, Maungati. At the type locality for the Maungati Gravels.

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Quaternary Deposits

Pleistocene gravels, sands, and silts are far more widespread tl~an

Recent deposits, which are almost restricted to the present flood plainsof the rivers. For the old flat-lying gravels and silts that overlie uncon­formably the Cannington Gravels at Maungati (see Fig. 6), the term111aungati Gravels is proposed.

The youngest Pleistocene deposit is a fine-textured. yellow loesswhich forms a capping of variable thickness over much of the area.Directly beneath the basalt at Mt. Horrible is an 18 in. layer of orange­yellow coloured, banded tuff overlying a fossil soil formed on yellowsilt. The presence of tuffaceous beds beneath the basalt was first re­ported by Haast (1865, p. 7 and map).

(Tl ) MAUNGATI GRAVELS

Type Locality: Left hank terrace of the Little Pareora River.

Sheet SIlO, Grid Ref. 534435.

The Maungati Gravels are similar in lithology to Cannington Gravelsbut they are not tilted, and are on the. whole less weathered and lesscemented and contain fewer sands and silts. Because of this similaritvin lithology it is very difficult to assign "old" high level terrace gravelsto either the Maungati or Cannington formations, in fact only inexposures that show two sets of "old" gravels separated by an un con­fonnity can the Maungati Gravels be identified with certainty.

STRUCTURE

Three major structures can be distinguished III the Pareora district.

Hunters Hills block, includi ng M1. N essing basin.

Cannington syncline.

Craigmore anticline-Mt. Misery block.

Hunters Hills block, including Mt. Nessing basin

This block is elongated in a northerly direction, and the strike ofthe greywacke and argillite comprising it is also northerly. It isseparated from the Tertiary rocks to the east by a major fault with athrow of about 4,000 ft. In general the clip of the Tertiary rocksincreases from about 10° to as much as 40° within a few hundred yardsof this fault. Tertiary beds in fault contact with greywacke or argillitecan be obse rv-«l at three places along the foot of the H unte rs Hills.At the Upper l'arcora Gorge the Craigmore Limestone is intenselyshattered and shows fault drag (see Fig. 7). From here the directio~l

of the fault can he accurately traced to the south since in three of the

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FIG. 6.-Cannington Gravels, dipping at about 25° and overlain by horizontalMaungati Gravels. Type locality for the Maungati Gravels, Maungati.

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FIG. 7.-Craigmore Limestone in fault contact with grey wacke and showing faultdrag. Upper Pareora Gorge.

valleys between the Upper Pareora Gorge and \Vhite Rock River thelimestone may be observed in proximity to greywacke. The ethertwo exposures of the fault contact are to be seen in the Motukaika Riverjust below Green's farm on the back road of the Hunters Hills. Thereargillite has been intensely shattered for a distance of 20 yards fromthe fault plane, and Tertiary rocks have been affected by small sub­sidiary faults for a similar distance on their side of the main fault.The upstream exposure is directly below the farmhouse in the right bankof the river and shows quartz grits and sands of Colliers Coal-measuresin fault contact with argillite. At the contact is a 3 in. to 5 in. layer ofwhite-, blue-. and black-streaked, extremely plastic fault gouge. Thequartz grits and sands are apparently faulted against a wedge ofSquires Greensand which is in turn faulted against Bluecliffs Silt.N one of the beds in thisi fault zone shows stratification. and the sub­sidiary fault planes are not clearly defined, which suggests that flowagehas occurred. At the second exposure, some 150 yards downstream,there is a fault wedge of pulverized argillite about 6 ft wide which hasTertiary rocks on both sides. The fact that the fault planes of thesesubsidiary faults and of the main fault all dip towards the HuntersHills at 60° to 80 0 indicates that the fault is probably reverse.

From the Motukaika River the throw along the Hunters Hills Faultdecreases to the south as in the north branch of the Little PareoraRiver at \V. Squire's farm. and in the Otaio River section ColliersCoal-measures occur in proximity to greywacke.

MOUNT NESSING BASIN

There are no Tertiary outliers within the Hunters Hills. but north­north-east of Mt, Ximfod a large fault splinter of greywacke departsfrom the main range in this direction, and between it and the main

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range is a narrow strip of Tertiary rocks preserved in the fault angledepression (Mt. N essing Basin). The fault splinter pitches to the norththe greywacke disappearing beneath Tertiary marine sands at the OpawaRiver. The fault forming the western boundary of Mt. N essing Basincan be observed in the northern extremity of the "badland gully" in theleft bank of the north branch of the Pareora River. Marine sands ofprobable Arnold age (see Fossil Localities) arc faulted against:trgillite which is extremely shattered for at least 30 ft from the faultcontact. The fault plane is very irregular here and dips from 30 to 70°to the west, which indicates that the fault is also oE the reverse type.I t is possible that on the eastern side of the southern extremity ofMt, X essing Basin there is a small fault of only a few feet throw. asa greywacke terrace rises very abruptly from within a few yards ofTertiary sands exposed in the bed of the Pareora River.

Canninqton Syncline

Cannington Basin has been eroded along part of an asymmetricalsyncline of Tertiary sediments which is cut off on the west by theHunters Hills Fault, and bounded on the east bv Mt, Miserv blockand Craigmore Anticline. At the northern and southern extren{ities ofthe basin. Cannington Gravels form the axis of the syncline and occuras high-level, slightly dissected terraces which form a natural geo­graphic boundary, There are two minor anticlines bordering this basinon the west and cut off by the Hunters Hills Fault. These are thesmall anticline at D. Squire's farm and the more extensive UpperPareora Gorge anticline. both of which trend at right-angles to theCannington syncline.

Craujmore Anticline-Mt. Misery Block

Craigmore Anticline is an asymmetrical fold with its steeply dippinglimb on the north-west side. The surface of the Craigmore Limestone,which forms the crest and limbs of the anticline. is pitted with numeroussink-holes (see Fig. 8). At the Lower Parcora Gorge the trend ofCraigmore Anticline changes from north-east to north-north-west, andthe steeply dipping western limb passes into a, fault to form the Mt.Misery tilted undermass block. Tertiary rocks have heen stripped fromthe upper slopes of the blackslopc of Mt..Misery lilcck to reveal a flatfossil plain surface (probably part of the pre-Tertiary peneplain). At thefoot of the Mt. Mise ry exhumecl "fossil" fault scarp near thePareora River is a small terrace of greywacke probably formed bystep-faulting. In the south-west, the Craigmore Anticline is cut off bya fault (the Maungati Fault) which is exposed in the left bank of thesouthern branch of the Little Pareora River at Maungati. The ex­posure shows steeply-clipping Cannington Gravels underlain hy theSouthhnrn Sand, both of which dip at 65° to the west. faulted againstfiat-lying Colliers Coal-measures which overlie greywacke.

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FIG. S.-Sink holes in the Craig-more Limestone along- the crest of Craig-moreanticline. Note also the slump topography (on the Little Pareora Silt) inthe south-east corner of the photograph to the north-west of the LittlePareora River (lower right). (Photo reproduced by permission of Landsand Survey Department.)

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GEOLOGICAL HISTORY

The remnants of an exhumed fossil peneplain which rise from be­neath the cover of Tertiary sediments on the back slope of Mt. Miseryblock and Mt. N essing fault splinter are probably part of the wide­spread, pre-Tertiary peneplain cut across thQ rocks of the undermass.The long period of erosion needed to form this peneplain impliescrustal stability during this time. The sequence of Tertiary rocks fromcoal-measures at the base, to marine limestones, to coal-measures andgravels at the top, indicates a complete cycle of sedimentation broughtabout by depression of the area beneath the sea, followed by upliftand return to land conditions. In view of the small variation in thetotal thickness of the marine Tertiary beds over the area mapped itcan be concluded that, during the period of subsidence and earlierstages of uplift, the movements were epeirogenic rather than orogenic.The presence of such structures as Cannington Syncfine and Craig­more Anticline indicate that shortly after the marine sediments emergedfrom the sea to become land the earlier regional epeirogenic movementschanged to more local orogenic movements (the "Kaikoura" Orogenyof Cotton, 1916).

As the marine sediments rose from beneath the sea, sediments erodedfrom the first emergent portions are likely to have been, deposited onthe more slowly rising land around (see Fig. 2 (b) ). Such seems to bethe origin of the Cannington Gravels. It is probable that the gravels,silts, and sands comprising this formation were eroded from the earlieremergent land which lay to the west of the Pareora District. Theabsence in these beds of fragments of Tertiary rocks is readily ex­plained by the fact that, with the exception of the Craigmore Limestoneand the various concretionarv bands, the bulk of the sediments con­sists of unconsolidated sands and silts and other easily erodable beds.In the Pareora district the Cannington Gravels are non-marine. butfarther east they are likely to have been deposited in a marine en­vironment, as have the gravels at Makikihi (Collins, 1953).

As the Kaikoura movements continued, irregularities of the reliefproduced by differential uplift to the east of the Hunters Hills wereprobably smoothed out as rapidly as they formed, by aggradation ofgravels derived from the erosion of the highland to the west. Finallya stage was reached during which there was an extensive piedmontalluvial fan or series of coalescing fans, similar to the CanterburyPlains but occupying a much higher elevation, extending from highup the Hunters Hills over the top of Mt. Misery block and CraigmoreAnticline to the sea (see Fig. 2(b), stages 2 and 3). As the HuntersHills and the blocks to the west continued to rise tectonically, this fansurface was built up by aggradation. Due to this aggradation and alsoto a slowing up of earth movements towards the close of the KaikouraOrogeny, the earliest deposited Cannington Gravels, at anyone place,were folded to a greater degree than those deposited later. and move­ment on the folds and faults probably had ceased by the time the

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uppermost gravels were deposited. Over the structural lows, such asCannington Syncline, the gravels were possibly thousands of feet thick,but over the structural highs, such as ~It. Misery block and Craig-moreAnticline, they were very thin or possibly absent in a few places.Moreover, numerous disconformities are to be expected over thestructural highs (at times when the rate of upli ft exceeded the rate ofaggradation of Cannington Gravels) and in many places perhapsonly the uppermost layers of Cannington Gravels were deposited.A thin veneer of gravel across, or adjacent to a structural high istherefore more likely to represent a layer from the youngest than fromthe oldest Cannington beds (see Fig. 2(b), stage 3). Where now ex­posed, the gravels overlie an eroded surface of either White RockCoal-measures or Southburn Sand, but over structural highs theycould have accumulated on older Tertiary formations or even directlyon the underrnass. This disconforrnity or angular unconformity be­tween the Canning-ton Gravels and the heels beneath increases inmagnitude towards the source area and structural highs, but probablydecreases to vanishing point where the gravels are marine (see Fig.2 (b) ). The field observation that the lower part of the CanningtonGravels consists mostly of silts. sand, and fine gravels, and the upper partof coarse gravels, can be related to the amount of relief in the sourceareas. During the initial stages of the Kaikoura Orogeny relief wouldbe relatively small, and predominantly fine sediments would he pro­duced. But as the movements intensified. relief increased, with theconsequent production of coarse materials.

The presence near the base of the Cannington Gravels of silt bedsup to 50 ft thick containing plant impressions suggests that at severaltimes in the early history of the lVIt. Misery block. uplift may havebeen so rapid that aggradation in the Cannington basin was arrested,and temporary ponding occurred. With the cessation or slowing upof the Kaikoura movements a long period of degradation has ensued andhas finally produced the present landscape. During this period ofdegradation there may have been intervals of aggradation, due toclimatic changes or minor earth movement. and Cannington basinmay thus have been partly filled and excavated several times. But thenet result has been degradation, which, guided largely by the buriedstructure as it hecame exposed, has resulted in the present topography.Tn the early stages of this period of degradation hef ore the excavationof Cannington Basin had begun, basalt was erupted to form a sheetwhich now- extends from lVIt. Horrihle to the sea. It seems probable thatdegradation had been in progress for S0111e time prior to the eruptionof the basalt, since at the point below the north trig. on Mt. Horribleonly a few feet of Cannington Grilvels are present beneath the siltunder the basalt, and farther to the north the silt beneath the basaltdirectly overlies Southhurn Sand.

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GEOMORP IIOLOGY

285

The effect of the deposition of the Cannington Gravels was to burystructures as they were formed. The effect of post-Tertiary erosionhas been to re-expose structures so that the present landscape showsvery close adjustment to the underlying structure, It is probable that1110st faults in the area were still active during the deposition of theCannington Gravels, and that the fault scarps were progressivelyburied hy these beds. thereby becoming "fossil" features. Post-Tertiaryerosion has subsequently exhumer! these "fossil" fault scarps.

Five features of the landscape require special mention. These are:

( I) The exhumed fossil peneplain on the hack slopes of :M1. Miseryblock and Mt. N cssing fault splinters, which is probably part of theextensive pre-Tertiary peneplain.

(2) The slump topography developed on the silts and clays of theCannington Gravels in the Motukaika Valley, and in the branches ofthe Little Pareora River west of Maungati. Similar topography isdeveloped also on the Little Pareora Silt on the north side of theLittle Pareora Valley (see Fig. 8), and on the west side of the LowerPareora Gorge.

(3) The numerous sinkholes on the surface of the Craigmore Lime­stone where it forms the crest and eastern limb of Craigmore Anticline(see Fig. 8). Many of these sinkholes form aligned groups, which joinwith discordant junctions the headward ends of surface streams drain­in gthe area. Other groups of sinkholes form "blind" valleys, not yetin surface connection (hut probably connected underground) withsu rface stream valleys.

(4) Interfluves in Cannington basin eroded in both Maungati andCannington Gravels, which have asymmetrical cross-profiles, appar­ently unrelated to the underlying structure (see Fig. 9). In profilethe back slopes of the ridges are inclined at about 5 to 10°. It is sug­gested that these features are possibly related to climatic effects. Inall cases the ridges trend in an easterly direction and the scarp slopeinvariably faces south, which is the shady side. Furthermore. wherethese ridges are followed back to the headwarrl ends of the streamsbetween them, it is founel that the streams have symmetrical V -shapedvalleys which become asymmetrical downstream, in, some cases withina few hundred yards of the valley head. An alternative explanation.that the asymmetrical interfluves are due to recent tilting to the north,does not seem likely in view of the general accordance of summitlevel of the crests ofl the interfluves.

(5) The anomalous position of the Little Pareora River in a longi­tudinal valley near and parallel to the crest of Craigmore anticlinesuggests superposition from the Canning-ton Gravel surface of aggrada­tion.

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FIG. 9.-Asymmetrical intcrfiuves eroded in Cannington and Maungati Gravels,Cannington basin. Hunters Hills with Mt. Nimrod (the highest peak in thephoto) in the background; upstream end of the Lower Pareora Gorge inthe foreground lower left. The Craigmore Limestone forming the steeplydipping north-west limb of Craigmore Anticline is in the middle left of thephoto. (Photo reproduced by permission of V. C. Browne.)

FOSSIL LOCALITIES

Otaio Gorge

Downstream of Colliers Bush is exposed an interrupted sequencefrom Colliers Coal-measures to the Craigmore Limestone. The con­tact with greywacke is not exposed. Isolated slabs (not in place) ofrichly fossiliferous pebbly (quartz pebbles) Otaio Gorge Sandstonelie in the bed of the river about 200 yards downstream from the roadbridge.

Dr J. Marwick (pers. comm .. 31 March, 1949) noted a scarcity ofBortonian species, and. on the general appearance of the faunule wasinclined at that time to correlate it with the ?upper Dannevirke series.

The following fossils were obtained from this conglomerate:Baryspira n.sp.Crassatellltes oustralis (Hutton)Crassatcllitcs sp.

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Cucullaea d. iuailiaocnsis AllanEoiurris n.sp.Hedecardium d. brunneri (Hector)Lnsoleniia n.sp.Lonqimactra n.sp.

?111agnatica sp.Monalaria n.sp.N ot ocallista (Fossacallistav hectori Finlay and MarwickN otoplejona sp.Paphirus n.sp.Polinices (Polmista) n.sp.Spiro coltnts n.sp.Struthiolarclla sp.Venericardia n.sp.Zeacolpus n.sp.

Bluecliffs and Southburn Road Cutting

In this locality is exposed almost the whole thickness of the Blue­cliffs Silt, but not its contact with the Graigmore Limestone. This isthe type locality for the Otaian stage of Finlay and Marwick (1947).The following is a list of characteristic (i.e. most common) fossilsfrom this type locality:

Alcithoe n.sp.Austrojusus (Neocola) apudalpha FinlayAustromiira n.sp.Austrotomo laiosi PowellAustrotonui neruosa PowellBaryspira aft. novaezelandiae (Sowerby)Baryspira robusta MarwickBathytonia haasti (Hutton)Cirsotrema lyra tum (Zittel)Cominula (Procominula) pulchra (Suter)Comitas [nsiiormis (Hutton)Comitas n.sp,Cucullara austrolis HuttonDentaliuni solidum HuttonFriainatica uauqhani (Marwick)Globisinum miocenicum (Suter)H ima (1\1irua) n.sp. . .Inquisitor amamoacnsis (Hutton)Lentipecten. hochstetteri (Zittel)Lima d. paleata HuttonLimopsis sealandica HuttonM arginella conica HarrisN eotturalcns (Fllsiguraiens) aff. flexicostata PowellN otacirsa clata (Suter)Notocorbula pumila (Hutton)Penion finlayi (Laws)Poirierla primioena FinlaySpinomel9n euelynae LawsSpinomelon mira MarwickSpissatella trailli (Hutton)Tanea socius (Finlay)Tj'phis (Typhinelills) hebelatus HuttonUberclla acerva LawsUberella I1I.Sp. aff. acerva LawsVexithara nodosolirata (Suter)X ynrenella aff. lepida (Suter)Zcacinninia biplex (Hutton)Zesilia dalli (Suter)

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Just opposite Drinnan's bridge, in the left bank terrace, the Blue­cliffs Silt passes into the Southburn Sand. The transition is first acolour change; the change in texture does not occur until higher upin th~ sequence. Samples for foraminiferal study were taken above andbelow this colour change (F 11432, F 11433, F 11434)* to see ifit was related to the Otaian-Hutchinsonian boundary but the samplesindicated an age not older than Hutchinsonian. The fauna was similarto that obtained from the fossiliferous horizons of the Southburn Sandat White Rock River and at the fault contact of the Cannington Gravelswith Colliers Coal-measures at Maungati. N otorotalui spinosa, (Chap­man ) is common and Virgulinopsis pustulate Finlay is present.

The Otaian Stage as defined hy Finlay and Marwick (1947) is saidto extend up to the brown "sandstone" in the. upper sands at South­burn (below Bluecliffs). Judged by the above, the upper limit of theOtaian would appear to lie in the blue silts .

The Southburn Sand crops out in many places f rom the Southburn roadcutting to Higginbotham Road, the dip gradually, decreasing from 7 0

to 30. A unique feature of the sands and sandstones here is the presence

of tubes about 1 to 2 cm in l length and 1 111m in diameter. Their firstappearance is approximately a hundred and fifty feet above the colourchange. their last in the uppermost exposed horizon of the SouthburnSand. which is very near the top. Between these two levels they mayhe found in practically all outcrops. Although they occur in both sandsand sandstones they are more common in the latter. Here thev arefound crammed in gre3t abundance in thin sandstone slabs (up to sixinches thick) to the exclusion of other fossils. They lie in the horizontalplane and are orientated in a north-east direction. A fragment of thissandstone was sent to Dr J. Marwick and the late Dr H. J. Finlayfor examination. The fossil is either Cadulus (mollusc) or Ditrupa(worrn-tubc ) .

On molluscan evidence Dr 1- Marwick places the upper horizon ofthese sands as H utchinsonian or Awamoan. The following J\folluscawere obtained from the uppermost horizon of the sancls:

Cad ulus 11.Sp.

Hiina d. sociclis (Hutton)l nsolentla d. pcreoraensis (Suter)

On foramini feral evidence (F 11435) the upper horizon of thesands here may he Awamoan, The late Dr H. J. Finlay stated (pers.comm., 19/3/49). "Notorotalia spino sa common, not many otherforamini Iera. Yet the fauna looks somewhat like a poorish OIW [ron:Pukeuri. and I have it strong impression that it may he Awamoan,though no species to prove it could be found."

*The,'e F numbers refer to foraminiferal slides held at the New Zealand GeologicalSurvey, Lower Hutt.

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D. Squire's Farm

There is an interrupted sequence here from the Little Pareora Silttu the Southburn Sand. The former crops out in the hill facing theback road of the Hunters Hills where it clips at about 27° to the east.)J ear the base of the exposure, layers of simple corals (Balano phylliahcctori Tenison-Woods ) occur, and beneath this horizon rounded quartzpebbles from Colliers Coal-measures are present in an earth flow.

The following details are from Dr Finlay's reports on foraminiferalsamples collected from the limestone cliffs to the east of the homestead.

The Holme Station Limestone was founel to be definitely of Whai-ngaroan age. A good fauna (F 11419) including:

Gaudrvina rcussi StacheRolali~lilla snlciucra (Stache)Ih'iycrilla inavnci ChapmanVayillltlhlOPsis cristellata (Stache)Vayiulllillopsis lioch stcttcri (Stache)

was obtained.

From Squires Greensand (F 11420), a fair fauna including

Linqulina d. lrartrunii ChapmanNotorotulio spinosa Chapman var.Voainulino psis n.sp.

indicated definitely a Duntroonian age. A sample was taken from analmost pure glauconite sand to see if any facies fauna changes occurred.\To fauna was obtained and the glauconite was reported as being veryworn.

The Craig-more Limestone contained a Waitakian fauna (F 11421,F 11422. F 11423). In the upper part of this stone were many Ostra­cods. and in samples f rorn the upper 20 ft in the outcrop in the leftbank of the river the following' are present (F 11424 to F 11431).

Anoiualinoidcs miosuturalis (Finlay)l risco puh-inulina turqidus (Finlay)Hacuslcre{{a hcciori (Finlay)Nolorolalia aft. sCITJta (Finlay)Nolorolalia d. spinosa (Chapman)Q uiuquelo culina n.spSiphoiJCllerilla aff. striatissinut (Stache )

Lotocr Gorqe of the Pareora Ri'verThe Otaio Gorg<.e Sandstone is exposed in the side of the road through

the gorge. It appears to he thicker than usual, and is for the most partunfossilif'erous. The concretionary sandstone layers and quartz pebbleconglomerates are not exposed. From the proximity of these sands tothe greywackc it can be inferred that Colliers Coal-measures is eithervcrv thin or not present here.

There are no cxposurc-, at the upper end of the gorge, but at the lowerend are interrupted exposures fr0111 the Otaio Gorge Sandstone to theSouthburn Sand at Holme station.

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Little Pareora River

This river has entrenched itself near the base of the Little PareoraSilt, which is exposed at several places along its bed from Maungati toits junction with the Pareora River. Near the junction with the Pareoraa middle to upper horizon of the silt is exposed, but upstream lowerhorizons crop out until at Maungati the Otaio Gorge Sandstone is ex­posed about 200 yards below the junction of the north and southbranches of the Little Pareora River. In the river-bed just aboveElworthy's bri-Ige the writer found a single fossil crab.

Maungati

The following Mollusca and Foraminifera (F 11417) indicativeof a Hutchinscnian age were obtained from the Southburn Sand under­lying the Ca-viington Gravels near the fault contact.

:MoT.T TTSCAAngulus sp.Glycymeris sp,Lentipecten sp,M aoritnactra SJl.Nucula d. sa qit iata SuterZcnatia

FORAMINIFERA

Notorotalla spinose (Chapman)Virqulopsis pnstulata (Finlay)

M otuleaika River

This locality is of interest stratigraphically as well as structurally inthat Squires Greensand contains a distinct facies fauna. The bestexposure of the greensand occurs in the second fault contact belowGreen's farm. The greensand differs from the usual in that it is con­siderably thicker (at least 30 ft). is very uniform in glauconitic con­tent, and contains numerous small rounded pebbles of quartz and softbrown argillite, both commonly t in. across. As well as the usualbrachiopods, which arc here. very rare. the fauna contains (F 11418)N otocallista Dentalium, Turridae and N aticidae, and the corals Flabel­lum. poroninam circulare Tenison-'Noods and N otocyathus pedicallatusTenison-Woods. A sample of the greensand was sent to Dr Finlay whostated (pers. comm., 19/3/49), "Quite a fair fauna, not older thanDuntroonian, but I cannot find anything that really limits it to this ageand it could be a little younger, perhaps Waitakian".

White Rocl? River

The following is a list of macrofossils from the Southburn Sandwhere it is exposed in the left bank of the 'White Rock River about30 yards upstream of the first bridge.

Acteon oualis (Hutton)Anomia triqonopsis (Hutton)Austroiusus (Zealandiella) subnodosa (Hutton)A ustrotonui d. excauatn (Suter)Austrotoma minor FinlavBaryspira (Alocospira) 'hebera (Hutton)

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N.Z. JOURNAL OF GEOLOGY AND GEOPHYSICS

Ob••rv.d and i"r.rr.d }Monty inferr.d Formational boundari••

Strike and dip of Mddin, Ind.qr•••

Trill Station wtthh.iqht in f•• ' 0..1.1.1.

Ba5alt

LEGEND

AlluviuM of floodplain, anel tow.r '.rra~..

&lunhtf. Silt

CraitMOr. lI...aton.,s.w., Grt...S0ft4 _41Hot-I Station UMI.&tOM

Llttl. ' ...ora Silt, Otalo Got,. SanditON.Ref Com.nCoal-NaaureJ

c..ywock.... Ar.,a.t.

N

Motor Rood

D~

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Syncline

REFERENCE

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5 III

511e 511q

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5110

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FIG. 1O.-Geological Map of the Pareora District, South Canterbury.

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292 N.Z. JOURNAL OF GEOLOGY AND GEOPHYSICS

Batillona n.sp.Cirsotrema n.sp.Conospirus huttoni (Tate )Dentaliuni aff. uaiunn HuttonDcntaliutn solidun: HuttonDosinia sp.Glvcyincris (Glyc}'/Ilerita) huttoni (Marwick)HimQl (Mirlla) socialis (Hutton)Limo-psis zitteli IheringN eoquraleus (Fllsigllralells) lept osonnis (Hutton)N otocorbula pumila (Hutton)Par cora striolata (Hutton)Penioii niaruriclei (Finlay)P oliuices huttoni IheringPteromyrtea laminata (Hutton)Scolpomactro continua FinlayStrombiiorniis aot eaensis (Marshall & Murdoch)Struthiolaria (Callllsaria) spino sa HectorTtmea sublata Marwick'Ttnnopleurn cxctrratn (Hutton)T'urbonitla spci!lhli LawsZcocolpu» (Tropicolplls) albola pis (Finlay)Zeacutninia j;areoraellsls (Suter)

INlAY

Dr Marwick (pers. cornm., 31/3/49) correlated the White RockRiver fauna with the Awamoan and suggested that some points of clif­ference arc probably the result of different station.

Dr Finlay reported a small microfauna in a sample from near thetop of the highest shell-bed (F 11415), in which N otorotalia.\pinosa (Chapman) is common ariel Virgulopsis pustulata (Finlay) ispresent. He considers the fauna to be no older than Hutchinsonian butit may be younger. The fauna was too small to give a definite decision.

Dr R. A. Couper reported as follows on samples of carbonaceoussand and sandv liznite from the White Rock Coal-measures in theWhite Rock Ri-;"er ~tction: "Only sample S 110/521 (L 1176) yielded aworkable flora. Among the species identified, Tricolpites tnaiauraensisCouper, Liliaculites intermedius Couper, and an undescribed new coni­ferous species all make their last appearance in Southland Series floras.Other key species in the sample indicate a Pareora to Taranaki age.Available evidence suggests a Southland age for the sample. Besidesthe fossil spores and pollen grains numerous specimens of microplankton(mainly hystrichosphacrids ) are also present, clearly indicating a marineof estuarine environment for the sample.

Sample S11O/520 (L 1175) yielded only a poor preparation (includ­ing hystrichosphacrids ) and no estimate of age could be made. SampleS 110/523 (L 1177) gave no flora."

Mt. Nessinq Basin

All the beds up to tbe limestones are exposed in this basin and evcrvformation other than the Craigmore Limestone and Squires Greensandis represented here hy a facies differing to a varying' degree from itscorrelative to the cast of the Hunters. Another difference is the con-

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1959] GAIR-PAREORA DISTRICT 293

siderable development of Squires Greensand which is at least 100 ftthick. Only those beds below the Craigmore Limestone remain in theportion of the basin to the south of the Pareora River. There the wholesequence consists mostly of marine sands of varying colour underlainin two places by thin lignites and clays.

The following divisions can be made:

(e) Rust-yellow sands:

(d) Green-blue glauconitic silts:(c) Yellow-white sands, poorly

fossiliferous:(b) Richly fossiliferous sands:(a) Clays, lignite seams, carbonaceous

shales:

Total minimum thickness:

io«25 ft

250 ft

15ft

12 ft

312 ft

Age

Whaingaroan

Bortonian

All the beds except those near the west fault (where the dip is 50° to60°) dip to the west at about 18°. Beds (a) and (b) are exposed intwo outcrops of somewhat different facies. The first outcrop is adjacentto the greywacke in the west side of the basin in the right bank of thesouthern branch of the Pareora. The succession here is:

(5) Grey-brown sand, fossiliferous Top

(Mollusca) : 6 in.

C4) Lignite: 6 in.(3) Carbonaceous dark brown silts: 3 ft 6 in.(2) Lignite: 3 in.(1) Sulphur-yellow coloured sand.

unconsolidated, sparsely fos-siliferous (Mollusca) : 10 ft Bottom

Bed 5 passes up into the rust-yellow sands comprising- division H "c .

The upper 5 in. of the sulphur-yellow coloured sand is fossiliferousbut the fossils occur onIv as casts or moulds and the sand is so loosethat it is impossible to collect a specimen for macrofossil study unlesssome means of "Iithifying" the deposit is devised. Fragments of kaolin­ised greywacke and argillite up to 2 in. diameter occur in this sand and inBed S. the grey-brown sand. The fossils in the latter were so poorlypreserved that no collection was made.

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294 N.Z. JOURNAL OF GEOLOGY AND GEOPHYSICS [MAY

The second outcrop of beds (a) and (b) is in the right bank of thenorthern branch\ of the Pareora about mid-way across the basin. ThisIS the best exposure of the lowest fossiliferous sands. The successionis from top to bottom:

(3) Grey-blue coarse sand, fossiliferous Top(Mollusca) and very iron-stainedin parts: 10 ft

(2) Blue sand, fossiliferous (Mollusca),intensely iron-stained in places, withsmall fragments of carbonaceousl11aterial: 1 ft

(1) Blue micaceous silt with shaley layers(Mollusca) : 4 ft Bottom

Bed 3 passes up into the yellow-white sand comprising division "c",

The state of preservation of the fossils is exceedingly poor butDr Marwick was able to place the age of these beds as probably Bor­toni an on the presence of the following Mollusca:

Barysbira sp,Dosinia sp,Gl)'c)'1I1cris (Gl~'c~'111crita) sp,Hedecardiuui bruIl11eri (Hector) or ioait aleiense (Suter)M aoriiellina sp.Mooricrypta sp.Muurca sp.Plcuromeris sp.Scalpo1l1actra sp,Spissatella (or Crasatellites) sp.f'cnrricardia d. acanth odrs SuterZcacolbus sp.

No foraminiferal faunas were obtained from these sands. About twohundred yards downstream from this outcrop white and yellow daysare exposed in the bed of the river and further down in the left hankpartly kaolinised greywacke crops out.

Division "c", the yellow-white sands, is exposed in the cliff-faces tothe north and south of the branches of the Pareora, Sands in the southare more mottled with iron-staining, hut fossils are more easily found.The fossils arc mostly casts and moulds so poorly preserved that allthat their presence demonstrates is that these sands are marine.

N ear the top of the "badland" gully at the western extremity of thiscliff-face these sands pass up into green-blue glauconitic silts comprisingdivision "d". Four subdivisions of these beds can he made:

(4) Blue silt, slightly glauconitic: 7 ft Top

(3) Dark blue-green glauconitic silt: 4 ft(2) Green glauconitic silt: 4 ft

(I) Brown glauconitic silt: 4 ft Bottom

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1959] GAIR-PAREORA DISTRICT 295

Foraminiferal samples were taken from each of these beds but allproved negative save Bed 4, in which a good fauna was obtained, whichproved a definite Whaingaroan Age (F 11416). This fauna included:

Cibicides thiara StacheEqaerella aff. ihlJ11gia FinlayGcudrvino rcussi (Stache)Cuttulina. regina (Brady, Parker, and Jones)GyroidilloidesG)'roidina aff. allani (Finlay)M arainulinopsis d. interruptus (Stacbe)Rotaliatina sulciqera (Stache)

Thus this blue silt is the correlative of the Holme Station Limestoneto the east of the Hunters Hills.

Some miles north of the Pareora River the calcareous greensandsand limestone crop out just north of Rocky Gully and in' theOpawa .River. In both these places the greensands are at least 100 ftthick, and they pass up into the typical Craigmore Limestone. whichis faulted against greywackc.

ACKKOWLEDGEMENTS

The writer wishes to thank Dr ]. Marwick and the late Dr H. J.Finlay for fossil identifications, and members of the Christchurch staffof the N .Z. Geological Survey for their helpful advice and criticism.This paper is based on a thesis for the degree of M.Sc. in geology atCanterbury University College 1949, that was carried out under theguidance of Dr R. S. Allan.

REFERENCES

COLLINS, B. W., 1953: Discovery of Pliocene Marine Fossils in South Canterbury,Proc. 7th Pacij'. Sci. Conqr. 2: 130.

COTTO)!, C. A., 1916: The Structure and later Geological History of New Zealand.Geol. Mag. 3 : 243-9, 314-20.

FINLAY, H. ].; MARWICK, ]., 1947: New Divisions of the Ne~, Zealand UpperCretaceous and Tertiary. N.Z. J. Sci. Tech. 28B : 228-36.

GAIR, H. S., 1949: The Geology of the Pareora District, South Canterbury. Thesisfor M.Sc. University of Canterbury, Christchurch.

GrDF:x, M. C, 1918: The( Succession of Tertiary Beds in the Pareora District,South Canterbury. Trans. N.Z.lnst. 50 : 244-62.

HAAST, J. YO)!, 1865: "Report on the Geological Formation of the Timaru Dis­trict, in Reference to Obtaining a Supply of Water". 13 pp. andsections, Christchurch.

---, 1879: Geology of the Provinces of Canterbury and Westland, NewZealand.

HARDCASTLE,]" 1908: "Notes on the Geology of South Canterbury". 62pp., Timaru.HECTOR, JA:YIES..1882: Progress Report N.Z. ucol. S1Ir1'. Rep. aeol. Explor. 1881 :

lX-XXXl1.

LAWS, C. R., 1933: New Tertiary Mollusca from the Timan! District, SouthCanterbury, New Zealand. Trans. «z.i;« 63: 315-29.

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l1ALI:-IG, P. B., 1933: The Geology of the Kakahu District, South Canterbury,New Zealand. Thesis for M.Sc. Univcrsity of Canterbury, Christ­church.

MARSHALL, P., 1916: The Younger Limestones of New Zealand. Trans, HZ. l nst .48: 87-99.

}''fA:<ITELL. G. A., 1850: Notice of the Remains of the Dincruis and Other Birds.and of Fossils and Rock-specimens, recently Collected by MrWalter Mantell in the Middle Island of New Zealand. Quarr.T.geol. Soc. Lond. 6 : 319-42.

'McKAY, A., 1877: Oamaru and Waitaki Districts. HZ..aeol. suru. Rep. ,iJeol. E xplor.1876-77 : 41-66.

----, 1882: On the Younger Deposits of the Wharekuri Basin and theLower Waitaki Valley. HZ. geol. suru. Rep. geol. Explor, 1881 :98-105.

PARK, J.. 1905: On the Marine Tertiaries of Otago and Canterbury with SpecialReferences to the Relations Existng between the Pareora andOamaru Series. Trans. H2. l nst . 37 : 489-551.

RAESIDE, ]. D., 1948: Some Post-Glacial Climatic Changes in Canterbury andtheir Effect on Soil Formation. Trans. rov, Soc. H2. 77 : 15.3-71.

T uoxrsox, J. A., 1914: Classification and Correlation of the Tertiary Rocks.H.Z. yeol. Sllrv. 8th aunu. Rep. : 123-4.

----, 1917: Diastrophic and Other Considerations in the Classification andCorrelation and the Existence of Minor Diastrophic Districts inthe Notocene. Trans. H.Z. I ust, 49 : 397-413.

----, 1926: Marinc Phosphatic Horizons in the Tertiary Limestones andGreensands of South Canterbury and North Otago and Brachio­pod Evidence as to their Age. HZ. I. Sci. Tech. 8B : 143-60.

UUUClT, G., 1947: The Physiography ,J{ the Parcora District, South Canterbury,New Zealand. Thesis presented for M.A. University of Canterbury,Christchurch.

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