New Zealand Soil Bureau Bulletin 35
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NEW ZEALAND. DEPARTMENT OF SCIENTIFIC AND INDUSTRIAL RESEARCH R. B. MILLER Director SOIL BUREAU BULLETIN 35 SOILS OF PART OF THE PORT HILLS AND ADJACENT PLAINS, CANTERBURY, NEW ZEALAND by E. GRIFFITHS Soil Bureau, DSIR Havelock North 1974 Wellington Price: $4.50 Edited by Janice C. Heine, Soil Bureau, and Q. W. Ruscoe, Information Service, DSIR ISSN 0077-9644 O Crown Copyright 1974 PRINTER, WELLINGTON, ZEALAND-1974 A. R. SHEARER, GOVERNMENT NEW 32333D-1,580/8/74 A CONTENTS page Abstract 5 .. .. .. .. Introduction 5 . Geology and Geomorphology Port Hills 5 . Adjacent Plains 7 . Climate 7 . Vegetation 9 . Soils 11 . Yellow-grey Earths 11 . Upland Yellow-brown Earths 15 . Brown Granular Loams 16 . .. Steepland Soils Related to Brown Granular Loams 20 . Soil Complexes 20 Gley Soils .. .. .. .. .. 23 .. .. .. .. Saline Gley Recent Soils 24 .. .. .. .. Gley Recent Soils 26 Yellow-brown Sands .. .. .. 27 .. .. .. Organic Soils 27 .. .. .. .. Erosion 28 . Land Use 28 . Classification of Soils for Land Use 29 .. .. .. Acknowledgments 29 . References 29 . Appendix: Soil Profile Descriptions 30 . Soils Index 36 .. .. .. .. .. Soil map of part of the Port Hills and adjacent plains, Canterbury, New Zealand Scale 1 : 31 680. Pocketed inside rear cover Extended legend of soil map: Summary of soil and some agricultural properties of soil mapping units. With Explanatory Notes. Pocketed inside rear cover 3 Insett Tables page 1 Correlation with other soil surveys 11 .. .. .. 2 Soils arranged pedologically I2 .. .. 3 3 Soils arranged physio graphically I . Figures page 1 Locality map 6 . 2 Relationship of soils to parent material and climate 7 .. .. 3 Location of rain gauge sites 8 . 4 Relationship of elevation to rainfall 9 .. .. 5 Soils of Upper Lansdowne Valley; complexes and an intergrade of a complex 10 . 6 Profile of Takahe silt loam I4 .. .. 7 Valley near Taitapu, with Takahe hill soils, Takahe silt loam, Waikuku sand, and Horotane silt loam I5 .. .. .. 8 Profile of Summit silt loam 17 . .. 9 Profile of Cashmere silt loam I 8 .. 10 Profile of Rapaki clay loam 19 . .. .. 11 Profile of an intergrade of the Summit-Rapaki complex 22 . 12 Profile of an intergrade of the Rapaki-Summit complex 23 . 13 Profile of an intergrade of the Rapaki-Summit complex, overlying loess 24 .. .. .. .. .. part Soils of of the Port Hills and adjacent plains, Canterbury, New Zealand by E. GRIFFITHS N.Z. Soil Bureau Bulletin 35, 1974. 36 pp, map, extended legend. ISSN 0077-9644 ABSTRACT The survey area can be divided into two distinct physiographic units-the Port Hills and the adjacent plains. The soils of the hills are formed on basalt, loess, and mixtures of basalt loess in proportions from pure basalt pure loess. There is distinct and varying ranging to a climatic gradient from subhumid on the plains and lower parts of the hills, to humid on the upper parts of the hills above 275-300 m. This is reflected in the soils - the zonal soils are yellow-grey earths on the lower parts of the hills, and yellow-brown earths on the upper parts. Brown granular loams (intrazonal soils) are formed on dominantly basaltic material. plains from On the adjacent the soils are recent, formed on alluvium derived the Wai- makariri River system and lacustrine sediments. The soils near Lake Ellesmere are strongly from it less saline and those away are saline. IN TR O DUC TION is physiographic part The area surveyed on the eastern margin of the units - the south-west to western of Canterbury Plain and on the western end of Banks the Port Hills, and the adjacent plain from Taitapu to Christchurch figure Motukarara. Peninsula, to the south of ( 1). Most of the area is in Halswell County, shown on The survey was made to complete soil information on NZMS2, sheets S84/4 and S84/7. It covers approx- a part of the Port Hills and plains which was considered imately 13 100 hectares* and is bounded by Lake a likely area for the growth of Christchurch. Basic soil plains Ellesmere in the south, Paparua County and Ellesmere information on both the hills and was required planning purposes, County in the west, Heathcote County in the north, and for the Summit Road in the east. It includes two distinct GEOLOGY AND GEOMORPHOLOGY PORT HILLS The hills are partly covered by a mantle of loess. The thickest deposits are found on north-facing slopes at low elevations (i.e., up to 270 m above sea level), although The Port Hills are the north-western to south-western some deposits on rolling tops near the summit are also sides of the erosion caldera that surrounds the volcanic thick. On moderately steep, south-facing slopes at lower crater centred on Lyttelton Harbour. Remnants of the elevations, and on all moderately steep slopes at higher main cone are andesitic with basalt occurring on the elevations, little or no loess remains. Loess deposition flanks at Halswell and Otahuna (Speight 1916). How- in Canterbury occurred mainly during the late Pleistocene ever, Liggett and Gregg (1965) suggest that the main flow and probably covered all the Port Hills. Under the peri- types are a mixture of andesite and basalt. The volcanic glacial conditions that would have existed in the Port material also consists of basaltic ash, tuff, agglomerate, Hills at that time, frost-lift and freeze-thaw would have vesicular basalt, scoriaceous basalt, and basic lava flows. mitiated erosion of the loess almost as soon as it was in Gebbies Pass area a series of slates and greywacke the deposited. Downslope movement initiated by prominent hills these is exposed, with rhyolite forming the on processes would have most effect on the shadier south- west side of the Pass. the facing slopes, which would remain frozen for consider- able periods during winter. Some of loess has *1 acre =0.4047 hectare the the 5 Inset l* (Speight 1916). Distinct been redeposited on lower slopes. Several distinct layers trench-like with steep sides formed heads of loess can be recognised, apparently deposited at differ- amphitheatres have at the of some of the found larger Streams which are mainly consequent ent times (Raeside 1964). Not all the layers are valleys. place do in cut subsequent valleys at any one and the thickness of those that character are now tending to diminutive inter- appear may vary considerably. and the subsequent tributaries are little in The structural features of the erosion caldera are mittent torrents that carry or no water the flat, residual sections of the volcanic cone, bounded by steep summer. In the lower reaches the valleys are owing carry loads. valleys which join in their higher reaches. These valleys to aggradation of streams unable to their Of on south-west radiate from the cone with their streams cutting back the spurs separating the valleys the dip slopes are longer towards the crater. They run in the direction of the and west of the caldera, the northern gentler Of few spurs running of the lava, at right angles to the strike, and are and than the southern. the RNER PEGASUS BAY VVAIMAKARlRI CHRISTCHURCH N Halswell ror Taitapu BANKS PENINSULA Motukarara Lake 1 Akaroa , CANTERBURY B/GHT Survey area Port Hills Main roads 0 10 km Figure 1 Locality map of survey area. north-west/south-east, both slopes tend to be short and ADJ ACENTPLA IN S steep. As the spurs descend from the summit, they level out at about 230 m above sea level for some distance Alluvium derived from the Waimakariri River system before continuing down to the plains, and this levelling- occurs on the plains, together with lacustrine deposits out is accompanied by a change from a rough hilly of the old Lake Ellesmere (which was much larger than present surface, with numerous outcrops of volcanic material, the lake and reached as far inland as Taitapu). patches plains to a smooth rolling surface. This change of slope may Small of loess have been found on the be a bench marking a former sea level (Speight op. cit.), outside the old lake margin. Remnants of an inter- but no evidence has been found to support this view; or mediate terrace of the Waimakariri fan exist to the the levelling-out may mark the end of a lava flow. south of Taitapu. Beach ridges associated with the Before reaching plains level, at or below 30 m, there is littoral zone of the old Lake Ellesmere rise to a height often another levelling-out (fgure 2). of 4.6 m at the mouths of the valleys north of Motu- The Port Hills reach a maximum altitude of 573 m karara and across the plain south of Taitapu. The plains at Coopers Knob, with most of the summit ridge being at Motukarara are only about 2 m above sea level, and 460 m above sea level. they rise to about 6 m near Taitapu. CLIMATE Rainfall records have been kept by the North Canterbury of rain per annum, and the higher parts (over 300 m,) Catchment Board, for Hoon Hay Valley and Cashmere about 1 020 mm. The rainfall on the plains is probably Valley since 1962. Eight rain gauges (fgure 3) are sited fairly well represented by that shown by the rain gauges in various parts of the catchment, ranging from valley at Lincoln and Christchurch which have an average of floor to the summit. Although figures are available for 633 mm and 668 mm per annum respectively. Most of only 6 years, the relative differences in rainfall are shown the rain is directional, coming from the south-west, to be consistent over this period (fgure 4) and give a fair the stations on the south-west side receiving more rain indication of the shadow aspect and altitude effect on the than those on the north and north-west.