Science Collected Works - Theses
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ItemThe sedimentary and tectonic structures of the Lower Devonian Liptrap formation, Victoria, Australia(University of Melbourne, 1978)The shore-platform and cliff exposures of the (Lower Devonian) Liptrap Formation were mapped around Cape Liptrap. In all, 3200 metres of interbedded sandstones and mudstones together with occasional slump beds were examined and the tectonic and sedimentary structures contained within them described in detail. In addition, the overall sedimentary and tectonic environments are discussed. The sediments were derived from two sources; a more distant provenance located on a granitic� metamorphic terrain in eastern Victoria and a local prevenance across the Waratah Fault located in Cambrian greenstones and Devonian sediments. The direction of overfolding of slumped beds indicates a palaeoslope from east to west, while current direction indicators show movement from the east. The sequence of sedimentary structures developed within sandstone-mudstone couples indicates emplacement of the sediments chiefly by bottom traction. Rapid deposition is suggested by structures indicating post-depositional instability with a variety of water-escape structures being developed. The overall sedimentary environment is interpreted as being that of a small-scale shallow water submarine fan deposit. Tectonic structures were developed under a low cover during a single phase of folding and regional cleavage formation - the Middle Devonian Tabberabberan deformation. Chevron folds plunge at low angles to the.north or south, while minor parasitic folds have a different but predictable orientation relative to major fold axes in that they diverge from the major anticlinal axes and converge on the synclines. This is caused by local reorientation of the overall stress field on the limbs of the major folds which have an initial plunge. Folds show evidence for generation at and migration from point sources with consequent rapid changes in plunge both between different folds and within individual folds. In the profile plane a cyclical change in fold form can be seen with single hinged chevron folds giving way to box folds which have two diverging hinges. These style changes are thought to reflect packing difficulties encountered during tightening of the folds. The regional cleavage is statistically axial planar to the folds and is developed as a penetrative differentiated layering best seen in the mudstones. Mica rich M foliae and quartz rich Q zones indicate pressure solution of the more soluble minerals (chiefly quartz) with concentration of less soluble minerals (chiefly mica) at the solution surfaces. Mechanical rotation and deformation of larger clastic flakes attended the shortening which accompanied this pressure solution process. The geometrical and spatial relationship between certain post-depositional soft sediment structures and certain hard rock tectonic structures is noted and a possible link between tectonic and sedimentary structures is suggested, in that they may have developed at the same time.
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ItemGeological investigations in the Murray Basin in New South Wales(University of Melbourne, 1962)
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ItemBonding and anharmonic vibration in some high symmetry crystals(University of Melbourne, 1977)
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ItemNo Preview Available[Published papers](University of Melbourne, 1974)
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ItemNo Preview AvailableA study of the recent sediments in Westernport Bay(University of Melbourne, 1979)A study of the bottom sediments in Westernport Bay has been made in order to determine :- (i) the areas of dominant sediment transport and deposition. (ii) The major sources of sediment into the bay. (iii) The range of processes that control the movement of sediment within the bay. Aerial photograph interpretation, field investigation and textural analysis data were used to distinguish 8 major facies in the bay, and approximately 600 sites were sampled to determine the textural characteristics of each facies. Advanced settling techniques were used throughout the textural analysis. A standardised procedure using settling techniques was developed and allowed for nearly-continuous measurement of grain size distribution. A computer program was written to collate the settling data in terms of grain settling velocity and normal grain size, and to present the results for direct interpretation. Minerological analysis was also undertaken to define sediment sources and movement paths within the bay, particularly in areas adjacent to artificial drainage entrances. The data was finally summarised in the form of maps which show the distribution of textural parameters, highlight sediment movement paths (particularly in critical channel areas) and locate the major depositional sites within the bay.
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ItemTrophic interactions among the macrofauna of an eelgrass community(University of Melbourne, 1978)This project investigated the dynamics of the trophic interactions between the macrobenthos and the predatory fish of an intertidal eelgrass community. The aim was to provide information on the ecology of many macrofaunal species inhabiting eelgrass flats in Westerport Bay; illustrate the dependence of fish species on these areas; and indicate the factors which are important in maintaining the structure of eelgrass communities. Investigations of the population dynamics of the 15 most abundant fish species showed that four species were permanent residents of intertidal flats, nine were tidal transients (i.e. move over the flats with incoming tides) and two were seasonal residents. Ten species breed over or near the eelgrass flats; while the remainder are represented only by juveniles. These areas are therefore important as nursery areas for immature fish of many species. The number and biomass of fish exhibited definite diel and seasonal changes. Of the 15 major species, nine were diurnal and five nocturnal inhabitants of eelgrass flats. Only one species was present in equal numbers during day and night. The total number and biomass of fish was lowest during the winter when most species moved away from the intertidal flats, presumably as a result of decreased food availability. Numbers and biomass increased during spring and summer (although at different rates) due to return of large fish and recruitment of 0+ aged fish from spring breeding periods. Maximum numbers and biomass were encountered during autumn, when there was the greatest density of large fish as well as 0+ aged recruits. Analysis of feeding relations showed that many fish depend on eelgrass flats for large proportions of their diets. Most, fish were carnivores and crustaceans were the major dietary group. Three species were omnivores consuming algae and detritus in addition to animal foods. Only one species, which was present in low numbers, consumed live eelgrass to a significant degree. Apart from permanent ontogenetic dietary shifts in the juveniles of some species, the diets of most fish exhibited seasonal changes which generally came about through fluctuations in the proportions of a few major prey types, rather than through prey switching. Most fish fed in distinct habitat patches within the eelgrass system, and exhibited marked patterns of food resource partitioning. The study of production by the major infaunal and epifaunal macrobenthic taxa indicated that the animals which are epifaunal on or among the eelgrass fronds are more productive than the infauna. Among the infauna, the active crustaceans are more productive than the sedentary infaunal polychaetes, and this was probably a result of the higher levels of predation on active crustaceans. Total secondary production in heavily-grassed areas of the eelgrass flats was found to be almost twice that in bare mud and lightly-grassed areas. Measurement of the rate of food consumption by the major fish species indicated that most of the food for the fish fauna came from bare mud and lightly-grassed areas of eelgrass flats, and predation pressure (defined as the amount of secondary production removed by predatory fish) was much higher in these areas than in heavily-grassed areas. It was concluded that although physical stresses and the differing above-ground biomass of eelgrass in regions of the intertidal flats set limits on the number and type of species that can inhabit different habitat patches within the eelgrass community, predation by fish was probably the major factor influencing the structure of the macroinvertebrate guild of bare mud and lightly-grassed areas of eelgrass flats. Competition for space and food has probably played a major role in structuring the invertebrate guild of heavily-grassed areas. The distinct pattern of resource allocation among the species of the fish guild, as well as the morphological specializations for feeding exhibited by most species were explained as responses to interspecific competition for food. The habits of only one fish species appeared to be controlled primarily by predation.
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ItemAdaptability of the Janus abstract machine(University of Melbourne, 1978)This thesis is an investigation into the adaptability of Janus. The aspect of adaptability which is of specific interest is the optimization of space occupied by software written in Janus. CHAPTER 1 places this project within the context of previous work on adaptability and portability. Techniques which enhance portability and adaptability of software are reviewed and the objectives of this project are defined. CHAPTER 2 describes the hardware and software used to carry out the research. Related work on the portability of Janus is also reviewed here. CHAPTER 3 is an exposition of the interpretive code into which Janus is translated. Design criteria are presented and their implementation discussed at length. CHAPTER 4 evaluates the results of the project with respect to the set goals and suggests areas for future research.
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ItemTaxonomy and evolution in the fern genus cheilanthes in Australia(University of Melbourne, 1978)A revision of the fern genus Cheilanthes on the basis of examination of herbarium and field-collected specimens. Fifteen species are described for Australia, and these are divided into four groups comprising species considered to be most closely related. One hitherto unrecognised subspecies is described and two long overlooked species are resurrected, one of which is based on new morphological criteria. A formal description of every known species is given, followed by a description of its intraspecific variation, habitat, distribution, range, cytology (including chromosome numbers for some species), spore morphology (studied by scanning electron microscopy) and gametophyte morphology. A key to the Australian species of Cheilanthes follows their formal description and discussion. Apogamy is found to be widespread in the genus Cheilanthes in Australia and is thought to be significant in enabling it to survive in areas of uncertain rainfall. In addition, a study is made of the drought tolerance of the gametophytes of four southern Australian species of this arid zone genus, and it is found that they possess an ability to survive complete desiccation at very low humidities. The origin of the genus in Australia is discussed in terms of the known plant migration routes to the continent, and it is concluded that Cheilanthes probably entered Australia by at least three major routes, giving rise to a variety of species.
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ItemWave transformation over a coral reef(University of Melbourne, 1978)In Hawaii, Australia and other tropical islands, most coastal areas are protected naturally by a shallow coral reef. The fringing reef presents an extremely complex environment due to complex bathymetry, large energy loss by breaking, friction, and scattering, and the highly non-linear behavior of impinging waves. Thus, the nearshore processes on reefs occur in distinctly different patterns from that on sandy coasts. The large ocean waves break on the edge of the reef, reform over the reef creating multiple-crest waves of attenuated height and shorter period. The wave height and period distribution are therefore modified significantly due to wave breaking, secondary wave formation, bottom friction, and reflection processes. The peaked swell energy-spectra in deep water widens as the waves enter shallow water as a result of redistribution of energy into the low and high frequency ranges from the peak frequency due to the unique nature of wave-reef interaction. Information on such modifications is very limited, particularly for correlated field measurements. Knowledge of wave characteristics leeward of a reef is necessary in numerous engineering or scientific endeavors, such as the assessment of beach stability, design of coastal structures, and prediction of coral growth under water motions. This report provides some new light concerning the wave transformation and modification of a train of ocean waves as it progresses from deep water through breaking on a reef and on into the shallow water beyond. Field measurements of sea-level yariations versus time were made at seven points along a 1650 ft long transect on the southern shore of the island of Oahu (21�-17'N, 157�-52'W) in Hawaii from July through September 1976 in water depths from 35 feet in deep water off the reef and from 1.0 to 3.5 feet on the shallow reef. The variabilities of wave heights, wave periods, wave spectra, as a function of locations on the reef were studied in detail. The wave height data were tested for (a) Rayleigh distribution, (b) Truncated Rayleigh distribution, and (c) Weibull distribution and periods tested for a symmetrical distribution (Longuet-Higgins, 1975) and Weibull distribution. It was found that both the wave height and period distributions fit the Weibull probability density function with a high degree of correlation at all positions on the reef under a variety of environmental conditions. The statistical ratios of wave height and period parameters were established for both offshore and reef locations, The time-series were analyzed by both Fourier analysis and zero up-crossing procedures. The energy spectra for different positions on the reef are compared. Contours of cumulative energy density in seven frequency bands against each position on the reef showed the shifting of energy from the peak, A design spectrum with the shape of Weibull distribution is presented with procedure given to obtain the Weibull coefficients which govern the spectrum peakedness. A zero up-crossing spectrum (ZUS) is defined and compared to the Fourier spectrum. They are similar but not identical. The benefits and disadvantages of ZUS were discussed, particularly for non-linear wave environment in shallow water. The ZUS contains an inherent height and frequency relationship. It can be used to simulate field spectrum in a flume which can only generate monochromatic waves. Further, the cross spectrum, wave celerity, and the number of consecutive high waves were discussed in this report. Many computer programs and subroutines developed during this study for certain procedures and mathematical procedures will be useful for future wave data analyses.
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ItemNo Preview AvailableStudies in marine botany(University of Melbourne, 1978)