Soils of Eltham county and the tephrochronology of central Taranaki : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science

Copyright is owned by the Author of the thesis. Permission is given for

a copy to be downloaded by an individual for the purpose of research and

private study only. The thesis may not be reproduced elsewhere without

the permission of the Author.

SO I LS OF ELTHAM COUNTY AND TH E

TEPHROCHRONOLOGY O F

C ENTRAL TARANAKI

A thes i s p resented i n parti a l fu l fi l ment of the req ui remen ts fo r th e deg ree of

Docto r of Ph i l osophy i n Soi l Sci ence at Mas sey Uni vers i ty

by

A L I SON MARGARET FRAN KS 1984

...•

^,

•.

Fronti s p i e ce . V i ew a cros s the s outh o f E l tham Co unty , to the no rth -wes t , wi th Mt . Egmont i n the background , from T i ri moana Road , a t Nl29/917395 . The l andsc ape shown here compri ses an upl i fted ma ri ne bench ( Ka i a tea Te rrace ) overl a i n by l a hari c bre cc i a ( E l tham Lah a rs ) and th i ck vol can i c ash . Soi l s a re

mapped as Stratford hill-Stratford association.

ABSTRACT

The s oi l s o f El tham Co unty wes t of th e Patea Ri ver , a re descri bed and the i r di s tri buti o n s hown on a map at a s ca l e o f 1 : 50 , 00 0 . The s o i l ­ formi ng fac to rs a re di scussed w i th part i c ul a r emph as i s on t h e so i l parent

1 ma teri a l s , w h i c h range from vol ca n i c a s h i n the wes t , to peat and

s ed i men ta ry roc k , ma i nl y s i l tstone and s ands tone , i n the ea s t . An account i s g i ven of the g enes i s and h i s tori cal deve l opment o f the Ngaere and

El tham Swamps and a c l as s i fi ca t i on made of the El tham pea t .

A deta i l ed account i s g i ven o f the s trati gra phy of th e l ate Qua ternary teph ras i n centra l Taranaki . Ei gh t n ew tephra uni ts (p2 , p l , E5 , E4 , E3 , E2 , E l a nd Ma hoe ) a re des cri bed , w i th type secti ons and reference l ocal i ti es des i gnated . I sopach maps of thei r di s tri buti on a re presented and an

attempt i s made to correl ate thes e teph ras w i th those further no rth . Deta i l s a re g i ven o f the wes ternmo s t occ urrences of Ao kaute re Ash and the i mpl i ca t i on s o f these for the Late Q ua ternary i n Ta ranaki a re exami ned .

Petrogra ph i c s tud i es , X- ray fl uores cence and chemi cal ana l ys i s o f ti tanomagneti tes by i n ducti vely-coupl ed a rgon pl asma emi s s i on spe-ctros copy ( I . C . P . ) a re a l so a pp l i ed to effect pos i ti ve i denti fi cati o n and corre l ati on of the tephra s . The compo s i ti on o f the l i th i c Ma nga n u i tephra i s

es tabl i s hed as basa l ti c ..

The morphol o gy and phys i ca l p ro pert i es of th e so i l s a re des cri bed as are the s o i l mapp i ng uni ts empl oyed i n th i s s u rvey . Characteri s t i cs of the component members of the mapp i ng uni ts a re g i ven i n a n extended l eg en d . Fi fteen s o i l taxonomi c uni ts have been recogn i s ed a n d named i n the s o i l s urvey . Des cri p t i ons des i gned pri mari l y fo r corre l ati o n and reference purpo s es a re prov i ded for each of the taxonomi c un i ts . The s o i l s a re

al s o rated i n terms of thei r l i mi ta t i ons fo r pas toral c ro pp i ng , horti c u l tural , fores t ry and u rban uses and i n terms of thei r val ue for food prod ucti o n .

The pos i ti on o f the boundary between S tra tford and Egmont soi l s i s es tabl i s hed and a bas i s for di s t i n g u i s h i ng the two s o i l s i s proposed . By exami n i ng two s teep l and s ubca tchments i n deta i l a n i ns i ght i s provi ded i n to the w i de range of vari ab i l i ty found i n the s teepl and soi l s i n the eas t of El tham Co unty . An i nd i ca t i o n o f the presence o f vol c an i c ash or i ts ab sence due to ero s i o n i s gai ned by a pp l y i ng the phos phate retenti on and a l l o phane tes t . Th i s a l so pro vi des a n unders tandi ng o f the pa t tern of paren ta l materi a l vari ab i l i ty .

Fi nal l y , s el ected l a bora tory anal ys es h ave been c ho s en to hel p characteri se the chemi c a l a n d phys i ca l properti es o f fi ve yel l ow-brown l oams , a g l ey , an i n te rg rade between yel l ow- brown l oams and recent s o i l s and an organ i c soi l from E l tham Coun ty . Deta i l ed a na l yti cal data from ten New Zeal a n d So i l B ureau reference s i tes i n Ta ranaki a re i nc l uded fo r comparati ve p urposes .

i i i

AC KNOWL EDGEMENTS

I wou l d l i ke to thank my s upervi sors D r . V . E . N ea l l a nd Dr. J . A . Pol l ok . D r . Neal l •s pati ent g u i dance a nd Dr . Pol l o k•s enthus i asm were much

apprec i a ted .

I am g rateful to my col l eag ues Mr . R . C . Wa l l ac e , and Dr. R . B . S tewa rt , who provi ded hel pful a dvi ce and constructi ve cri ti c i sm. Thanks a re a l so

due to Mr. J . H un t , S o i l B u rea u , D . S . I . R . Wel l i ng ton , for assi s tance wi th the X-ray fl uore s cence, to Dr. J . Lee , Appl i ed B i ochemi s try D i vi s i on , D . S . I . R . Pal merston No rthffor I CP ana l ys es o f the ti tanomagneti te sa.nd +o f\lQ),-i zw.\t,�.nO. Soi I Bu.re.a.\A 1or +he.

ve�r£.nce

^s·rte CA.nctl;iS"es.

Ac knowl edgemen t i s g i ven to New Zea l a nd Soi l B u rea u , Depa rtment o f Sci ent i fi c a nd I nd u s tr i a l Research , for fund i ng t h e proj ect 11So i l a nd As hbeds i n Tara nak i 11 • I n parti cul ar s peci a l recogn i ti on i s g i ven to Mr. R . H . W i l de and Mr . J . D . Cow i e of New Zea l and So i l Bureau for fi e l d corre l ati on and enco uragement .

I must a l s o thank Mrs . D . Syers for h er effi c i ent typ i ng and Mr . M . R . Lew i s for data ana l ys i s .

Fi n a l l y , I o ffer g ra teful th anks to Ms . S . L . Marx and other fri ends , i n both Ta ranaki and Pa l mers ton North , and my fami l y , who h ave been

supporti ve thro ugh o u t .

FRONT I S P I ECE ABST RACT . . ACKNOWLEDGEMENTS TABLE OF CONTENTS L I ST OF F I GURES L I ST OF TABL ES L I ST OF PLATES

TABLE OF CONTENTS

CHAPTER 1 . I n troducti on 1 .

2 .

Previ o us Work

Gene ra l Des cri pti on of Area

CHAPTER 2 . So i l fo rmi ng envi ronmen t o f El tham Co unty 1 . Phys i og ra phy

2 . Vegetati on 3. C l i mate . . .

4 . Soi l Parent Materi a l s

i . Reg i onal Quaterna ry H i s tory . . . . i i . Quate rnary H i s tory o f E l tham County 5 . Drai nage and I ron Movemen t

6 . Genes i s a n d H i s to ri cal Devel o pment o f the Ngaere and El tham Swamps .

CHAPTER 3 . Teph roch ronol ogy o f Central Ta ranaki 1 . I ntroducti on . . . . 2 . Defi n i ti ons and Termi no l ogy .

.

3 . H i s to ri cal Backg round and P revi o us Work 4 . Method of S tudy . .

5 . Stra t i g raph i c Un i ts .

.

Page i i i i v

V

vi i i x i xi v

1 6

10 1 1 1 5

2 3 24 34 37

5 1 5 3 5 5 58 6 1

V

CHAPTER 3 .

6 . Sys temati cs

i . Late Quate rnary Tep h ras o f Cen tra l Ta rana k i . i i . The Wes ternmos t Occu rre n ces o f Aoka utere As h

and Imp l i ca t i ons for the Late Quaternary i n Taranak i . . . .

CHAPTER 4 . Mi nera l ogi cal I denti fi ca t i on of Centra l Tarana ki Teph ras 1 .

2 . 3 . 4 .

P rev i o us work .

X- Ray Fl uores cence Spectrometry

Chemi cal Ana l yses of Ti tanoma g neti tes from Taranaki Teph ras . . . . . Mi n e ra l ogy o f the Tep h ra Seq uence

CHAPTER 5 . Soi l s o f El th am County

1 . S o i

1

Mapp i n g and Taxonomi c Uni ts 2 . S o i

1

Gro ups i n S urvey Area

3 . Soi l Taxonomi c Uni ts . . 4 . S o i l Mappi n g Uni ts . .

5 . Di s t i ng ui s h i ng Stratfo rd Soi l s from Egmont 6 . An I ns i gh t i n to the Vari a b i l i ty of

the Steepl and Soi l s . . .

CHAPTER 6 . Labo ra tory Analyses

S o i l s and Sampl i ng S i tes . Resul ts . . . .

pH Mea s urements Organi c Matter . . Phospho rus . . .

Cati o n Exch�nge Properties Rese rve Pota s s i um and Mag nes i um Sul ph u r . . . .

. ^. . .

Soi l s .

1 . 2 . 3 . 4 . 5 . 6 . 7 . 8 .

9 . Aci d-Oxal a te Extrac tab l e I ro n , Al umi n i um and S i l i con . 10 .

1 1 . 1 2 . 1 3 .

B u l k Dens i ty . . . . Mo i sture Retenti on . . . Al l o phane and Tota l C l ay Concl us i on . . . .

Page

6 2

85

9 1 92

97 103

1 15 123 125 146 155

1 84

2 1 9 224 232 2 34 2 36 24 1 249 249 255 26 1 264 2 6 7 267

CHAPTER 7 .

REFERENCES

APP E N D I CES

Cone

1

u s i ons . ^. . . ^. . . . ^. . ^. . . . . ^{. .} .

I .

I I . I l l .

I V . V . V I . V I I .

Li s t of Strati graph i c Secti ons Men ti oned i n Text . . . . Aoka utere As h Local i ti es Deta i l ed Descri pti ons of Two Re fe rence Local i ti es Extended Legend

Soi l L i mi ta ti ons for Use Soi 1 Taxonomi c Uni t Sheets Sma l l S ea

1

^{e Maps . .}

So i l Map i ns i de back cove r .

Page 2 7 3

2 76

287 289

29 1 305 3 19 332 4 1 1

vi i

Fi gure

1 . 1 1 . 2 2 . 1

2 . 2 2 . 3 2 . 4 2 . 5

2 . 6 3 . 1

3 . 2 3 . 3

3 . 4 3 . 5 3 . 6 3. 7 3 . 8 3 . 9

3 . 10 3 . 1 1 3 . 1 2 3� 1 3 3 . 14

L I ST OF F I G URES

Locati on of El tham County . . .

Pri nci pal s t reams and ri ve rs i n El tham County Mean annua l ra i nfa l l i s ohyets , Ta ra n a k i reg i on

( Offi ci a l New Zeal and , Me teo ro l ogi cal Offi ce data 194 1 - 1 9 70 ) . ^. . . . . . . Quaternary geo l og i cal map of E l tham County Locati on o f the Ngaere and El tham Swamps Ngaere secti on survey map ( 189 5 )

Contour map o f Ngaere and E l tham Swamps a t 100 1 i n te rval s . . . . . . P rofi l e o f E l tham peat nea r Rawh i ti ro a Roa d Di stri but i on of wel l dra i ned s o i l s o f central and s outh ern Tarana k i as governed by the di s tri but i on of teph ra . . . . Loca l i ty map of Taranaki s howi ng s tudy a rea Strati g raph i c secti ons refe rred to i n tex t ( for l oca l i ty detai l s see Appendi x I ) I sopach map of un i t p2

Appearanc e of uni t E5 . I s opach maps of uni t E5 Appea rance of un i t E4 . I sopach map s of un i t E4

Corre l a t i on co l umns 1 - 8 from near I n g l ewood to Type Sect i o n , Mangatoki S tream . . . Appeara n ce o f un i t E3

I s opa c h map o f un i t E3 Appea rance o f un i t E2 Appea ra n ce o f uni t E l

Appearance o f the Mahoe tephra

Page

7 8

1 7 2 6 38 40

42 48

59 60

60 65 67 69 7 1 7 3

74 76 7 7 80 8 2 8 4

Fi gure 3 . 1 5

3 . 16

4 . 1

4 . 2

4 . 3

4 . 4 4 . 5

4 . 6 4 . 7

5 . 1

5 . 2

Th i ckness

(

^{i n mm}

)

and i so pach s fo r

Aokautere As h i n central and s outh ern Tarana k i . I s opachs

(

a t 1m i nte rva l s

)

o f teph ri c materi a l s post-20 , 000 yea rs B . P . i n Taranak i . . . . C l as s i fi cati on of rocks 1 1 typi cal l y a s s oci ated w i th andes i te s i n orogen i c a reas 11

(

^after

Tay l o r , S . R . , 1969 , p 45

)

^{. . .} . . . . . Pa rke

r

s I n dex versus % K20 fo r

the tephra s equence . . . .

Graph of manganese va l ues versus z i n c va l ues fo r the Taranaki teph ras

P rofi l e of E l tham peat from El tham Swamp S ec t i on exposed i n upper pa rt of d ra i nage d i tch , Durham Road . . . . Di agram to s how ra nge o f aug i te va l ues i n th e teph ra s equen ce , Kaupokonui - p 1 Di agram to s how range o f augi te val ues i n pre - p l tephras . . . .

Hypotheti cal c ros s - section of El tham County s howi ng s o i l seri es i n rel ation to l ea ch i n g , dra i nage and parent materi a l s . . . Gran ge and Tayl or ' s reconna i s s ance s o i l map of wes tern Taranaki mod i fi ed to s how

d i s tri but i on o f Egmo n t and Stra tfo rd s oil s e ri es i n vi ci n i ty of s tudy a rea . . . . 5 . 3 Modi fi ed s o i l map of part of Ta ranak i i n

Page

88

90

95

96

1 02 106

1 07

1 1 1

1 12

122

1 56

v i c i ni ty o f s tudy a re a by N . Z . S o i l Bureau , 1954 . . . 1 57 5 . 4

5 . 5

5 . 6 5 . 7

5 . 8

Map to s how p resent k nown di s tri but i o n of Stratfo rd and Egmo n t soi l s i n vi c i n i ty o f s tudy a re a . . . . S ampl i ng s i tes o f a Patua s o i l , Burre l l s o i l , four S t ra t fo rd s o i l s , a S tratford fi ne topsoi l vari ant and th ree Egmon t s o i l s . . . . El eva t i on ve rsus pHH 2o a t�� and 1m depth Fl ow d i a gram to a i d f i e l d i denti fi ca ti on of Stratford s e ri es , S t ratfo rd s eri es f i ne tops o i l vari a n t and Egmont s eri es . . .

Loca ti on o f s teepl and a reas i n central E l tham Coun ty

1 62

1 7 1 1 74

183 185

i x

Fi gure 5 . 9 6 . 1

6 . 2

6 . 3

6 . 4

6 . 5

6 . 6

6 . 7 6 . 8 6 . 9

6 . 10

6 . 1 1

6 . 1 2

6 . 1 3

6 . 14

6 . 15

6 . 16

Loca t i o n of s teepl and s tudy a reas

Locati on of s oi l s i te i nfo rma t i on referred to i n s o i l ana l ys es sect i o n . . . . . . . Va l ues fo r pHH 0 and pHNaF i n the

s o i l toposeque

fi

ce of th i s s tudy . . Val ues for pHH 2o and pH NaF i n the s o i l cl i mos eque nce of th i s s tudy

0 . 5M H 2S04 extractabl e phosphorus val ues i n the s oTl Cl i mos equence of th i s s tudy . . Phosphate rete n t i on val ues i n the s o i l

c l i mosequence o f th i s s tudy for s i x s e l ected Ta ra n a k i s o i l s . . .

. (

^{I Bases )}

Base saturat1o n CEC pH7 NH40Ac i n the s o i l c l i moseque nce . . . .

Reserve pota s s i um val ues fo r ni ne Ta ran a k i s o i l s Rese rve magne s i um val ues fo r ni ne Tara n a k i s o i l s Phos phate- extra ctabl e sul phate vers us phos ph ate retenti on fo r s eventeen s el e cted Tarana ki s o i l s Phos ph ate-extractab l e sul ph ate val ue s i n a s o i l toposequence of th i s s tudy . . .

Phosphate- extra c tabl e s ul ph ate val ues i n the s o i l cl i moseqeunce of thi s s tudy

Aci d-oxa l a te extrac tabl e al umi n i um val ues i n a s o i l topos equence of thi s s tudy Aci d-oxa l a te extractabl e i ron i n the s o i l c l i mosequence and toposequence of th i s s tudy Aci d-oxa l a te extractabl e i ron versus phos ph ate retenti on for seventeen s e l e cted Taranaki soi l s Bul k dens i ty and to tal po ros i ty o f

s i x sel ected Tarana k i s o i l s . . . . H i s to grams to s how rel a ti ve amoun ts o f

Total Cl ay a n d Al l ophane i n fi fteen Taranaki s o i l s

Page 185

223

233

233

240

242

245 250 2 50

252 2 54

2 54

256

257

2 60

262

268

Tab l e 1 . 1

2 . 1

2 . 2

2 . 3

2 . 4

2 . 5

2 . 6 3 . 1

3 . 2 4 . 1

4 . 2

L I ST OF TABLES

Correl a t i on of s o i l seri es i n th i s survey wi th s o i 1 sets of "Genera

1

survey of the s oi l s of N o rth I s l and , New Zea l a n d " ( N . Z . So i l Bureau , 1 9 54 ) and un i ts o f other so i l surveys i n Taranaki Month l y and annual ra i nfa l l fi gures for

R i verl ea between 19 13- 1980 ( i n mm) . Suppl i ed by N . Z . Meteoro l ogi ca l Servi ce N . Z . Meteoro l ogi cal Servi ce ra i nfa l l norma l s for El tham and Omoana 1941- 1970 ( i n mm )

from N . Z . Meteorol ogi cal Servi ce Mi s e . Pub . 145 N . Z . Meteoro l og i ca l Serv i ce summari es of

c l i matol og i ca l obs ervati ons to 1980 for S t ra tford Demo n s trati on Farm . . . . N . Z . Meteo ro l ogi cal Serv i ce summari es o f c l i mato l og i c a l observati ons to 1 980 for S tratford Moun ta i n House . . . . . . . . Rel a t i ons h i ps between South Tarana k i mar i ne terraces and vol cani c acti vi ty i n wes tern Tarana k i a s a dopted i n thi s survey

( Adapted from Pi l l ans , 198 1 ) . . . Bul k dens i ty val ues fo r the El tham peat C h ronol ogy and d i s tri buti on of pri n c i pal Quaterna ry vol can i c depos i ts in cen tral and eas tern Taranaki . . . ^.

Granul ometri c c l a s s i fi cati on of pyro c l a s ts a nd o f un i moda l we l l sorted pyrocl asti c depos i ts Major e l emen t ana lyses by X- ray fl uo rescence o f a teph ra s equence i n Tarana k i . . . . Chemi cal a n a l yses of ti tanomagneti tes

from Tarana k i tephra s . . . ^.

4 . 3 Percentage augi te , hornb l ende and hypers thene

Page

5

1 8

1 9

2 1

22

25 49

52

54

9 3

98

i n the teph ra s equence . . . . . . 1 04 4 . 4 Rati os of ferromagnes i an mi nera l s i n

the teph ra s equence . . . .

4 . 5 Rati os of ferromagnes i an mi nera l s i n teph ra

. . . 109 s amp

1

es from El tham Swamp a nd Durham Road . . . 1 10

x i

Tab l e 5 . 1 5 . 2 5 . 3

5 . 4 5 . 5

5 . 6 5 . 7 5 . 8 5 . 9 5 . 10 5 . 1 1

5 . 12 5 . 1 3

5 . 14

6 . 1 6 . 2

6 . 3 6 . 4

6 . 5

6 . 6

6 . 7

So i l mapp i ng u n i ts a rranged phys i og ra ph i ca l l y S o i l taxonomi c un i ts a rranged pedo l og i cal l y So i l members w i th i n a s s oci ati ons a n d the i r rel at i o n to topog ra ph i ca l s i tes . . . . Teph ras c u rre n t l y recogn i s ed i n El tham county Range of e l eva t i o n and rai n fal l , l a nd form and mean annual a i r temperature under wh i ch

S t ra tford , S t ra tford fi ne topsoi l vari a n t and Egmont so i l s a re found . . . . . . Range of general morph o l ogi ca l pro fi l e features pHKCl and pHH 2o res u l ts

pHN a F res u l ts .

Phos phate reten ti on res u l ts

% Decreas e of 15-bar water res u l ts

We i ghted average 15- bar moi s ture retenti on - fi el d mo i s t and a i r dry . . . .

KC l -extracta b l e a l umi n i um res ul ts . . . . N . Z . Meteoro l og i cal Servi ce s umma ri es o f c l i ma tol ogi cal obs ervati ons t o 1980 for Te Wera Fores t . . . .

Al l ophane tes t and p hos pha te retenti on va l ues for Area 1 and Area 2 . . . . Deta i l s o f the e i g h teen soi l s i tes i n Taranak i Res ul ts o f ch em i c a l and phys i ca l a n a l yses of s el ected Taranaki s o i l s . . .

Rati ngs for chemi c a l properti es . .

Di a gnos ti c p roperti es o f 11Amo rphous materi al domi nant i n the exchange compl ex11 ^{• • • • • •} Organ i c matter

(

% Organ i c C x 1 . 7

)

^{i n}

seven teen Taranaki s o i l s . . . . I norgan i c phos phorus fracti on s o l ubl e i n 0 . 5H2S04 as a percentag e of i norgan i c phosphorus i n s even teen Tarana k i s o i l s E ffecti ve base s a tu rati on of e i g h teen s o i l s from Taranaki . . . .

Page 1 16 1 1 8

1 21 1 60

1 64 168 1 7 3 1 7 5 1 7 6 1 78

1 7 9 1 8 1

1 94

2 16 220 225 2 29 2 3 1

2 35

2 39

244

Tab l e 6 . 8

6 . 9 6 . 10

6 . 1 1

6 . 1 2

Exchangeab l e a l umi n i um as a percentage o f ECEC of s e ve n teen s o i l s from Taranaki Co rrel a ti on matri x between a l l vari ab l es

Ra ti o between sodi um pyrophos phate extractabl e a l umi n i um and i ro n and c i trate-di th i on i te a l umi n i um and i ron . . ^. . . .

1 5-bar water con tent fo r seven teen s o i l s i n Taranak i . . . . . . . . C l as s i fi cati on o f s o i l s from Taranaki a cco rd i ng to So i l Taxonomy and th e 1978 Andi sol Propos a l . . . .

x i i i

Page

248 2 5 3

259

2 66

2 7 2

Pl ate

Fronti s p i ece

2 . 1 2 . 2

2 . 3

2 . 4

2 . 5 2 . 6 2 . 7 2 . 8 2 . 9 2 . 10

2 . 1 1 2 . 12

3 . 1

3 . 2

3 . 3 3 . 4

L I ST O F P LATES

Vi ew acros s the so u th of E l tham Cou n ty , to the north -wes t , w i th Mt. Egmon t i n the �ack g round , from Ti �moana Road . . V i ew o f Ma nagami n g i d i stri c t , l ook i ng north-we s t , above Mangami ngi S tream . Vi ew of Mang ami n g i d i s tr i c t . S tratford Formati on i n the foregro und .

Look i ng north-we s t between Mounta i n Roa d a n d Boyl an Road . E l tham Lahars i n the

foreground . . . . Vi ew o f Mangami n g i di s tri c t , l oo k i n g wes t . Patea Ri ver i n the foregro un d wi th Opunake terrace and S tratford

terrace above . . . .

Pungare h u Formati o n , near Lower S tuart Road

Mt . E gmon t . Lah a r mo unds o f the Warea Forma ti on . Warea Lahar exposed on Upper Auroa Road

Opua Lahar exposed on E l tham Road Mangawhero s oi l , near Ri verl ea Vi ew north of the Ngaere Swamp from Rawhi ti roa Roa d . . . .

Expos ed roots of a Dacryca rpus dacrydi oi des ( Kah i k a tea ) . . . . Secti on exposed i n d i tch s howi ng B urre l l

l a pi l l i , Kaupoko n u i teph ra , Maketawa tephra , a n d Manganui tephra . . . ^. . . . .

Sect i on exposed on Opunake Road , 0 . 6 km from Mahoe . Type sect i o n for p2B , p2A and p1 . . . . Deta i l o f teph ras p2A and p 1 ( Kori to teph ra ) Secti on expose d near Ta ri k i . . . ^. Deta i l of s ecti on exposed a t Mahoe ,

on Opunake Roa d . . . ^. . . . V i ew o f secti on exposed on Opunake Road , a djacent to Mangato k i S tream . Type s ec t i on for E4 teph ra . . . .

Page

i

1 2

1 2

29

29 3 1 32 3 2 3 3 35

39

39

4 7

6 4 64

67

70

Pl a te

3 . 5 3 . 6

3 . 7

3 . 8

3 . 9

3 . 10

3 . 1 1

5 . 1 5 . 2 5 . 3 5 . 4

5 . 5

5 . 6 5 . 7 5 . 8 5 . 9 5 . 10 5 . 1 1

5 . 1 2 5 . 1 3 5 . 14

5 . 1 5

Deta i l o f E 4 teph ra a t Wa i ngongoro Road Deta i l o f E 3 teph ra on Pembroke Roa d , 1 . 5km s o u th from Barcl ay Roa d . .

Vi ew o f s e c t i on exposed on Pembroke Roa d , 1 . 5km s outh from Barcl ay Roa d .

Reference l ocal i ty for E2 . . . . Deta i l o f E 2 a t the type s ect i o n ,

on Opuna ke Road , above the Wa i ngongoro Stream Reference l ocal i ty for the Mahoe tephra , on Opunake Road , 0 . 6 km from Ca rd i ff

Secti o n exposed on Ti ri moana Road s howi ng

the Oma h i na Tephra i n terbedde d i n a ndes i tic ashes Sect i on a djacent to Opunake Road , n ear

Rona l d Roa d s how i n g the Aoka utere As h Rowa n s o i l , Uppe r Mangawhero Road Rowan s o i l near Uppe r Mangawhe ro Road Ri verl e a s o i l , near E l tham Road . . Ma kaka s o i l a t the type secti on , near Upper Mangawhe ro Road . ^. . . . Lowga rth s o i l , a t the type s e c t i on , near Lower Has ti ngs Road

Kah u i soi l co re , near Ri verl ea Ti poka s o i l , near Auroa Road Ha ngata h u a so i l , nea r Mana i a Roa d

S tratford so i l , nea r Lower H a s t i ngs Road Stratford fi ne tops o i l vari a n t on H i c ks Road Egmo n t s oi l , 1 km wes t of Mokoi a , a l ong mai n Wangan u i -Hawera h i g hway

S tee p l a n d s tu dy A rea 1 . S teep l a n d s t udy Area 2 .

Expo s u re of moderatel y consol i da ted s i l ty s ands tone bel ongi ng to the Matemateonga Fo rma ti o n at Mangami ngi Saddl e . . . V i ew from s tudy A rea 1 l ooki ng south-ea s t

Page

7 1

7 6

79

80

84

86

89

1 2 7 1 2 7 1 2 9

1 29

1 3 2 132 135 135 169 1 69

169 188 189

1 9 1 1 9 1

XV

5 . 1 6 Ri dge profi l e Area 1 . ^. . ^{. .} . . . ^. 200 5 . 1 7 I ntermedi a te steep s l ope profi l e , A rea 1 202 5 . 1 8 I nte rme d i a te s teep s l ope pro fi l e , Area 2 ^. 202 5 . 19 Eroded s l ope s i te , A rea 1 ^. . ^{. .} . ^. . 204 5 . 20 Profi l e from zone o f l ocal accumul a t i o n

at foo t o f eroded s i te . ^. 2 04

5.2 1 Accumul a t i on s l ope p rofi l e , Area 1 . 206

5 . 22 Eroded s l ope s i te , now s tab i l i sed 2 10

5 . 23 Eroded s l ope p rofi l e . 2 1 0

5 . 24 Vi ew north of a cc umul a t i on s l ope

s i te , Area 2 ^. . . 2 1 2

5 . 25 Acc umu l a t i on s l ope profi l e 2 1 2