Go to National Library of New Zealand Te Puna Mātauranga o Aotearoa
Volume 77, 1948-49
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Abstracts And Titles.

Geology Sub-section.

On the Occurrence of Natural Artesian Springs.
By G. Leslie Adkin, Geological Survey.

This paper described the occurrence of groups of springs rising under hydrostatic pressure through, and forming low mounds on, flood-plain alluvium in the Koputaroa area, Horowhenua County, Wellington. The adjacent topography and the underlying Quaternary geological formations were described. The artesian character of the springs was demonstrated. The origin of the individual conduits of these springs has eluded explanation, but the presence of such springs in other localities would serve as an indicator of perhaps otherwise unsuspected artesian water supplies.

The Pleistocene Snow-line and Glacial Control in New Zealand.
By R. W. Willett, Geological Survey.
On the Tertiary Fixation of Two Recent River Courses in New Zealand.

It was suggested that at Ohai (Southland) a river, only recently captured, marks the approximate course of an ancient Tertiary river; and that the Manawatu River follows a Tertiary strait through the Ruahine Range. Stress was laid on a rude correspondence between Tertiary and Recent physiography.

Demonstration of the Rate of Rounding of Beach Boulders.
By J. A. Bartrum, Auckland College.

This paper appeared in the Journal of Geology (U.S.A.), vol. 55, November, 1947.

The Present State of Knowledge of the Miocene-Pliocene Boundary in New Zealand.
By H. J. Finlay, Geological Survey.

Boundaries between Eocene, Oligocene, and Miocene in New Zealand are fairly well defined by index foraminifera. If Tongaporutuan is Sarmatian, and Opoitian improbably lower than Plaisancian, the intervening Kapitean may be Pontian, but evidence is conflicting. Urenui and Upper Tongaporutuan present problems in correlation locally and with Indo-Pacific.

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Spores from the Birchwood Mine Coal, Ohai, Southland, N.Z.
Figs. 1, 2, 4, 11, 16, 17, 19 and 25: Pteridophyte (?) spores. Fig. 6: An example of an angiosperm pollen grain. Note the position of the furrows (cf. Fig. 10). Figs. 7, 8, 12, 13, 14, 20, 21 and 24: Angiosperm pollen grains. Fig. 10: A example of a pteridophyte spore. Note the position of the triradiate tetrad scar (cf. Fig. 6). Fig. 15: A fungal spore. Figs. 22 and 23: cf. Nothofagus pollen.

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Spores from the Birchwood Mine Coal, Ohai, Southland, N.Z.
Figs. 1, 2, 5, 6. and 6a: Angiosperm pollen grains, Figs. 3 and 14: Pteridophyte (?) spores. Figs. 7 and 10: Compound angiosperm pollen grains, arranged in tetrahedral. tetrads. Fig. 15 An aggregation of spores. Fig. 16: A large spore with a very thick exine—possibly a megaspore.

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Conifer Pollen Grains from the Birch wood Mine Coal, Ohai, Southland, N.Z.
Fig. 1: Side view of 3—winged conifer pollen grain (cf. Podocarpus dacrydioides) Fig. 2—Distal view of 3—winged coniter pollen grain (ef. Podocarpus dacrydioides). Figs. 3 and 4. Smaller 3—winged conifer pollen grains. Fig. 5: Distal view of conifer pollen grain. Note the knob-like protuberances apparently associated with the-attachment of the wings. Fig. 6: Another view of a Fig. 5 type. Fig. 7: Distal view of a partly collapsed Fig. 5 type. Fig. 8: Proximal view of a Fig. 5 type. Fig. 10: ef. Dacrydium. Figs 11, 12. 15. and 16 ef. Podocarpue.

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The Upper Senonian Transgression in New Zealand.
By E. O. Macpherson, Geological Survey.

This paper will appear in the N.Z. Journal of Science and Technology.

Geology of South-west Hokianga District, North Auckland.
By H. J. Harrington, Geological Survey.

Basic Igneous Rocks of the Otepopo-Mount Charles District.
By W. N. Benson, Otago University.

Notes to Accompany a Geological Map of North Canterbury.
By B. H. Mason, Canterbury College.

This map, which was a compilation from published maps by Prof. R. Speight, from unpublished field-sheets of the Geological Survey, and from reconnaissance work the author undertook to fill in the considerable gaps, could not here be published owing to its size. The information, with Dr. Mason's consent, is incorporated in a geological map of New Zealand the Geological Survey has prepared and will shortly issue.

The Present State of the Geological Map of New Zealand. Mr. M. Ongley, Geological Survey, opened the discussion.

High and Low-rank Metamorphism, a Field Geologist's Viewpoint.
By H. W. Wellman, Geological Survey.

Metamorphism of schists was treated as the extension of low-rank metamorphism due to depth of burial. A metamorphic column analogous to a stratigraphic column has been built up from New Zealand sections and approximate maximum depth of burial given for all ranks from lignite to Chl. 4 schists.

Fulgurites from Dune Belt near Levin.
By J. J. Reed, Geological Survey.

This paper will appear in the N.Z. Journal of Science and Technology.

A Crystalline Specimen of Vivianite from Ashhurst.
By J. J. Reed, Geological Survey.

This paper will appear in the N.Z. Journal of Science and Technology.

Lava Injection of Carbonized Tree Trunk at Auckland.
By J. A. Bartrum, Auckland College.

This paper appeared in the N.Z. Jour. Sc. Tech., vol. 28, 1947, pp. 188–94.

Inclusions in the Serpentinite at Harper's, near Wellsford, Auckland.
By J. A. Bartrum, Auckland College.

This paper appeared in the N.Z. Jour. Sc. Tech., vol. 29, pp. 18–32, 1947.

Revision of the Brachiopoda of the Lower Devonian Strata of Reefton, New Zealand.
By R. S. Allan, Canterbury College.

The brachiopods of the Reefton mudstones have been re-studied at the U.S. National Museum in Washington, D.C. The fauna possesses affinities with that of the Oriskany sandstone horizon, the Deerpark stage, of eastern North America. This paper will be published in the Journal of Paleontology (U.S.A.).

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Some Undetermined New Zealand Tertiary Fossils.
By J. A. Bartrum, Auckland College.

Tectonic Scarps and Fault Valleys.
By C. A. Cotton, Victoria College.

The category of tectonic scarps includes besides “true” fault scarps many which might be classed as fault-line scarps, but only such of these as have been exposed by erosion in a first cycle. Monoclinal scarps may also be tectonic, together with combinations of monoclinal and fault scarps.

Faulted and strongly deformed land surfaces are everywhere subject to rapid dissection, but accumulation forms, bahadas or aprons of alluvium, are not as commonly developed in association with them in humid as in semi-arid regions such as the North American Great Basin. In humid regions undercutting by rivers also leads to some erosional modification, so that many humid-region scarps bear but little resemblance to type forms selected from Basin Range scarps.

The Awatere fault-scarp type, as found in New Zealand, is contrasted with the Basin Range type. Scarps of the Awatere type are not necessarily fringed by bahadas; and in some cases they have been undercut by rivers.

Minor fault scarps, although undoubtedly formed abundantly in seismic regions, may be difficult to detect except when quite fresh. The last traces of these to remain in a mature landscape are jogs and notches in the crestlines of spurs and ridges; but such evidence of faulting is of uncertain value.

The facets of a dissected tectonic scarp, though they may be very flat and strikingly co-planar, rarely preserve actual fault surfaces.

Fault valleys, as distinguished from purely erosional fault-line valleys, are occupied by consequent rivers, and such rivers aligned on faults are fairly common. Besides the consequent valleys that are situated in fault angles of a block mosaic there are probably some that are walled on both sides by fault scarps related to a single fault zone. Where reversal of fault movement has taken place, opposed scarps are produced by upheaval first on one side of the fault line and then on the other. Reversal of fault movement is not uncommon. Some fault movements now “in reverse” in New Zealand will, if the faults remain active, make trenches that are potential fault valleys.

Fault valleys in major fault angles are in many cases long lived. In the case of relatively minor fault-angle valleys that are formed in districts with considerable prefaulting relief the valleys may be expected to develop along rivers already fault-guided, perhaps in fault-line erosional valleys. In such cases, though the appearance of some relation to a fault will persist, the faultangle or tectonic origin will remain obvious only as long as the fault scarp on the line remains fresh.

The Hanmer Plain and the Hope Fault.
By C. A. Cotton, Victoria College.

The east—west trending Hope Fault, a major dislocation, which has been regarded by some authors as collinear north-eastward with the Kaikoura Fault, has its upthrow on the south side.

A sunken and sinking area that borders the fault on the north side has hecome the Hanmer Plain. Along the south side of this there are river terraces, with a peculiar history which testify to differential uplift.

Up the Hope River there has been movement on the fault in historic and recent prehistoric times; but this latest movement has been locally transcurrent.

Revival of Major Faulting in New Zealand.
By C. A. Cotton, Victoria College.

This paper has been published in the Geological Magazine, vol. 84, 1947, pp. 79–88.

Awatere Fault Trace and Tarndale Drainage.
By H. J. Harrington, Geological Survey.

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Earthquake Origins in the New Zealand Region.

Early work by Hogben in locating earthquake origins in the New Zealand region was discussed. It was shown that serious errors are likely to arise in attempting to locate epicentres from macroseismic data without adequate instrumental records. The general distribution of epicentres in the New Zealand region was discussed; and it was shown that certain types of earthquakes appear to be confined to definite regions. Future requirements for further earthquake location were outlined.

Pedology Sub-Section.

Soil Erosion in the Southern Half of the North Island, New Zealand.
By L. I. Grange, Soil Bureau, D.S.I.R.

Maps were displayed showing the distribution of: (1) no soil erosion, (2) wind erosion, (3) slip erosion, and (4) sheet and slip erosion undifferentiated.

The wind erosion occurs on the light and friable pumice soils and on yellow-brown loams derived from andesite ash, and is serious in the high country of central North Island. Slipping is related to the underlying parent material, being most serious where it exposes shattered Cretaceous argillites and mudstones, as erosion of the rock follows, leading to the formation of wide, steep-sided gulches.

On 29 per cent, of the soils surveyed, there is no soil erosion; on 40 per cent., erosion is leading to slow deterioration of the land; and on 31 per cent., erosion is leading to rapid deterioration. The third division needs immediate action to determine its utilization; parts that are suitable for agriculture should have conservation measures introduced as soon as possible.

The Soils and Land Utilisation of the Waimea County, Nelson.
By Sir Theodore Rigg, Cawthron Institute.

Types of Soil Erosion in New Zealand.

Some of the causes of accelerated or soil erosion were briefly discussed. The effect of burning, grazing and cultivating in predisposing soils to soil erosion is supported by the results of some measurements.

An attempt was made in this paper to describe briefly the types of accelerated erosion common in New Zealand.

Soil Erosion Types Compound Types
Wind erosion
Sheet erosion Sheet and wind
Creep erosion
Soil creep Sheet and creep; terracettes
Scree creep
Solifluction
Flow erosion
Earthflow Creeping earthflow
Debris avalanche
Mudflow
Slip erosion
Soil slips
Earth slips Slip and earthflow
Slump Slump and earthflow
Subsidence Tunnel-gully
Gully erosion
Gullied earthflow
Gullied slip
River erosion
Bank erosion Undercut flows, slips, slumps

General agreement on description and recognition of types in the field is essential to progress in soil conservation.

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Soil Drainage in Relation to Agriculture.

A review of farm drainage in New Zealand, and its importance and effects on soil, plants, animals, and production was given. The need for further farm drainage was emphasised, and the factors limiting its use outlined. The economic research, and extension aspects of the subject were discussed.

Soils of Hutt and Makara Counties.

Twenty-nine soil types and eleven sub-types have been recognised in Hutt and Makara counties, and the distribution of each of these was shown on a soil map on a scale of one mile to one inch. The soils were classified into Podzolic Yellow Earths, Podzolic Yellow Loams, Skeletal Steep, Skeletal Recent, Meadow, Organic, and Saline Groups. Essential characteristics such as colour, texture, structure, depth, and extent of leaching of profiles representative of the soil groups were described and illustrated by lantern slides of profiles and tables of analyses. Examples were given of the relationships between the soil characteristics and the soil-forming factors of climate, vegetation, parent material, topography, and time, and the formation of the soils was explained.

A detailed description and soil map will be published in a bulletin of the Soil Bureau, D.S.I.R.

The Classification of New Zealand Soils.

Soil classification consists of two operations: the establishing of soil units and the arranging of these units into groups so that accumulated soil knowledge can be used more effectively.

The soil unit is the soil type, and is based on a study of the soil profile.

The arranging of the units into groups by using any one of the soil-forming factors, climate, parent material, topography, soil life, or time, has proved to be unsatisfactory.

Marbut early formulated the idea that soils should be classified on their own characteristics. In his scheme for soil classification he states: “The fundamental point of view regarding classification in which the work of the [United States] Soil Survey has led is that it is an arrangement of soil units into groups on the basis of their characteristics and not on the basis of the supposed or partly proved causes which have produced these characteristics.” The danger here is that the classification is likely to become empirical.

The classification of soils should be genetic. Soils are the product of five formative factors, and Jenny has shown that to be entirely satisfactory the system of classification would have to be five-dimensionable. We can, however, simplify the problem by combining the effect of several factors into a process and subdividing on the stage to which the process has advanced. This is the way the geomorphologist has arrived at his genetic classification of land forms.

Such a classification will stimulate inquiry into soil formation. It will be a vital classification that will change and evolve as our knowledge advances, but this will not lead to undue confusion in the use of soil maps, since the soil units will remain fixed. Pedology cannot progress if it pins its faith to an empirical classification; that way the pedologist becomes an unworthy servant of the agriculturist and the engineer.

Pedology and Chemistry of the Yellow-grey Loams of Hawke's Bay.
By I. J. Pohlen and J. K. Dixon, Soil Bureau.

The material of this paper has been published in a bulletin of the Soil Bureau.

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Soils of the Motueka District, with Particular Reference to the Tobacco and Hop Soils.
By E. T. Chittendon, Cawthron Institute.
Pedology and Chemistry of the Canterbury Plains Soils.

By C. S. Harris and R. B. Miller, Soil Bureau.

The material of this paper is to be published in a bulletin of the Soil Bureau.

Pedology and Chemistry of the Canterbury Downland Soils.
By G. M. Bruere, Soil Bureau.

The material of this paper is to be published in a bulletin of the Soil Bureau.

Laboratory Aids to Pedology.

Laboratory analyses supplement field observations in the recognition and interpretation of soil horizons. Chemical methods used in classifying soils include fusion analyses, determination of soil reaction, organic matter, and water soluble salts. Particularly important are the base-exchange properties of soil colloids, and the estimation of the secondary soil minerals.

Soil Mechanics in New Zealand.

The role of soil mechanics in the attainment of better highways and more economically and safely designed structures was described. Examples were cited from various parts of the Dominion. The methods used were outlined. Analyses and lantern slides illustrated certain aspects of the work.

Clay Minerals and New Zealand Soils.

Clay minerals, that is minerals with particles of less than 0.01 mm. in diameter, were described and illustrated. A brief outline of technique was given and the relation of clay minerals to the soil types discussed.

The clay mineral in the Tekapuni sand, a podzol on the coastal sands near Dargaville, was shown to be quartz. The clay mineral from the Okaihau loamy clay, an ironstone soil derived from basalt, was shown to be gibbsite.

Phosphate in Soils.

The types of fixation of phosphate in soils, and the laboratory methods of extraction and estimation were outlined. The problems involved in such separations were discussed.