Volume 2, Number 2, 1968

This collection contains all the articles from Volume 2, Number 2, 1968 of the Earth Science Journal.

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    Coverpage and Contents
    (Journal Article, Waikato Geological Society, The University of Waikato, 1968) Waikato Geological Society
    Coverpage and Contents from the Volume 2, Number 2, 1968 of Earth Science Journal.
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    Notes on the belemnite content of the Heterian and Ohauan stages at Kawhia Harbour, New Zealand
    (Journal Article, Waikato Geological Society, The University of Waikato, 1968) Challinor, A.B.
    The belemnite content of the Heterian and Ohauan stages at Kawhia Harbour is described. Six major species or groups are differentiated, each of which ranges through several hundred feet of strata. Other minor elements are also present. Belemnopsis keari Stevens is shown to be present in only a restricted group of beds in the upper part of the Waikutakuta Siltstone, and Belemnopsis alfurica (Boehm) may be present in the upper Waikutakuta Siltstone. A system of informal belemnite zones is suggested. The belemnite succession is well defined throughout most of the Heterian stage, but poorly defined in the Ohauan, and further work is required in the upper and lower parts of this stage.
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    The effects of precipitation chemistry and catchment area lithology on the quality of river water in selected catchments in eastern Australia
    (Journal Article, Waikato Geological Society, The University of Waikato, 1968) Douglas, Ian
    The results of partial chemical analyses of precipitation and river water samples from north-east Queensland and south-eastern New South Wales are presented. Comparisons of water quality in the two areas are made using ionic ratios. While the sodium and chloride contents of precipitation in the two areas are similar, higher concentrations of calcium, magnesium and potassium occur in precipitation samples collected in New South Wales. Precipitation supplies between 25% and 70% of the total solute loads of the rivers studied. In the Southern Tablelands of New South Wales more chloride is supplied to the catchment areas than is removed by the rivers. River water quality reflects catchment lithology more than the climatic contrasts between the two study areas. Nevertheless, precipitation chemistry exerts an influence on the ionic ratios of these Australian rivers with low total dissolved solids concentrations.
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    Regression trend lines of ridges and swales on the emergent beach at Gisborne, New Zealand
    (Journal Article, Waikato Geological Society, The University of Waikato, 1968) Pullar, W.A.; Warren, W.G.
    The emergent sand-beach system at Gisborne consists of six recognisable groups of ridges and swales. It is about three miles wide and four miles long and rises gradually from 15ft above sea level at the coast to 40ft inland. From time to time the emergent beach has been mantled with air-borne volcanic ash including ash beds of the Waimihia Lapilli, Taupo Sub-group Members 9 - 13, Taupo Pumice, and Kaharoa Ash Formations. As the dates of these eruptions are known, the times of formation of the groups of beach ridges and wales have been determined as follows: Group 1: c. 9000 B.C. - c. 1400 B.C. Group 2: c. 1400 B.C. - (?) 850 B.C. Group 3: (?) 850 B.C. - c. A.D. 131 Group 4: c. A.D. 131 - c. A.D. 1020 Group 5: c. A.D. 1020 - c. A.D. 1650 Group 6: c. A.D. 1650 - A.D. 1956 Evidence of recent earth movements has been noted in ridges and swales of Group 1, and of possible movements in those of Group 3. Changes in sea level could not be established and were taken from Wellman and Schofield. No attempt was made to distinguish directly wind-blown sand from wave-deposited sand; instead, a shell layer (assumed to be associated with the intertidal strand) was used as a marker bed to indicate the approximate sea level at the time when the shells were deposited. Elevations of ridges and swales in each group were measured on a 15,000ft transect across the beach system. Then, overall linear and quadratic regressions as well as linear regressions for each group separately were computed. For both of the overall linear and quadratic regressions the trend lines show a fall seaward, but the separate trend lines for each group are as follows: Group 1: Highly significant seaward decline. Groups 2 and 3 combined: Very highly significant seaward decline. Group 4: Highly significant seaward incline. Groups 5 and 6 combined: No significant change. The departure of the regression trend lines within Groups 1 to 6 from the overall linear and quadratic trend lines suggests that the trends of elevation across the emergent beach at Gisborne should be regarded more as a series of discontinuous trends rather than as one overall continuous trend of seaward decline. Though the overall trend of declining elevation is seaward, the corresponding fall in sea level is likely to be more apparent than real because of compounding of fall in sea level with earth movements.
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    Distinguishing between the concepts of steady state and dynamic equilibrium in geomorphology
    (Journal Article, Waikato Geological Society, The University of Waikato, 1968) Abrahams, Athol D.
    The development of the concept of equilibrium in geomorphology over the past 15 years has been marked by linguistic difficulties due, in part, to the interchangeable use of the terms, dynamic equilibrium and steady state. It is here proposed that the range of steady state conditions constitute a sub-set of the range of conditions of dynamic equilibrium. The application of General Systems Theory is responsible for the introduction to geomorphology of the term steady state which in the strictest sense refers to the tendency for constant forms to develop. Gilbert understood dynamic equilibrium to mean an adjustment between the processes of erosion and the resistance of the bedrock. More recently, Leopold and Langbein described dynamic or quasi-equilibrium as a state of energy distribution which does not necessarily involve any regularity of form. However, dynamic equilibrium finds expression over space and time, in the evolving regularity and mutual adjustment of form elements. The development of regular erosional landforms reflects the tendency of the energy conditions of a system to make the final adjustment to the most probable state. If the manner of landform evolution is the point in question, the concepts of dynamic equilibrium and steady state become clearly distinguishable and system boundaries must be precisely defined. In field studies the theoretical approach is often superseded by the pragmatic approach. However, unless the logical distinction between the two concepts is made in the first place confusion will continue to persist in geomorphic analysis.
© 1968 Waikato Geological Society, The University of Waikato. All items in Research Commons are provided only to permit fair dealing for the purposes of research or private study. They are protected by copyright with all rights reserved unless otherwise indicated.