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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Inferring the Spatial Distribution of Regolith Properties Using Surface Measurable Features

Laffan, Shawn William, Shawn.Laffan@unsw.edu.au January 2001 (has links)
The aim of this research is to determine to what extent properties of the regolith may be inferred using only features easily measured from the surface. To address this research question, a set of regolith properties from Weipa, Queensland, Australia, are analysed. The set contains five variables, oxides of Aluminium, Iron, Silica and Titanium, as well as Depth to Ironstone. This last represents the depth of the layer from which the oxides are sampled.¶ The research question is addressed in two ways. First, locations where the properties are related to modern surface hydrology are assessed using spatially explicit analyses. This is done by comparing the results of spatial association statistics using geometric and watershed-based spatial samples. Second, correlations are sought for between the regolith properties and geomorphometric indices of land surface morphology and Landsat Thematic Mapper spectral response. This is done using spatially implicit Artificial Neural Networks (ANN) and spatially explicit Geographically Weighted Regression (GWR). The results indicate that the degree to which regolith properties are related to surface measurable features is limited and spatially variable.¶ Most locations in the Weipa landscape exhibit some degree of modern hydrological control of the oxide variables at lateral distances of 120 m. This control rarely extends beyond 300 m laterally, although such locations occupy distinct positions in the landscape. Conversely, there is an extensive part of the landscape where Depth to Ironstone is under hydrological control. This occupies most of the lower elevations in the study area. Depth to Ironstone represents the depth to the redox front where iron is precipitated, but may in some parts of the landscape control the distribution of the watertable by being impermeable.¶ For the correlation analyses, the highest correlations are found with those oxides most mobile in solution. The spatially local GWR results also consistently outperform the spatially global ANN results, commonly having accuracies 40% higher at the error tolerance used. Much of this can be attributed to the localized effects of landscape evolution. Comparison of the GWR results against the local sample mean indicate that there is a relationship between regolith properties and surface measurable features at 10-15% of sample locations for the oxide variables, and 22% for Depth to Ironstone.¶ The implications of these results are significant for anyone intending to generate spatial datasets of regolith properties. If there is a low spatial density of sample data, then the effects of landscape evolution can reduce the utility of any analysis results. Instead, spatially dense, direct measurements of subsurface regolith properties are needed. While these may not be a direct measurement of the property of interest, they may provide useful additional information by which these may be inferred.
2

The shell mounds of Albatross Bay: an archaeological investigation of late Holocene production strategies near Weipa, north eastern Australia

Morrison, Michael, michael@culturalheritage.com.au January 2010 (has links)
This thesis presents the results of an archaeological investigation of shell matrix sites, and in particular, shell mounds sites that occur around the shores of Albatross Bay, near Weipa on the north western Cape York Peninsula, northern Australia. It is the contention of this thesis that earlier approaches to the investigation of shell mound sites in northern Australia have tended to place too much emphasis on developing long-term explanatory models that gloss over explanations for the specific roles of these unique sites in past economic systems. While long-term explanations represent important contributions, it is argued here that short-term decadal scale modelling of the production systems associated with shell mound formation and use are required in order to fully understand the significance of the mid- to late Holocene emergence of these types of sites. A focus on production – defined in a substantive economic sense – is a suitable avenue through which archaeologists can expand our understanding of the role of these features in past gatherer-hunter societies, and their broader importance on longer-term time scales The thesis thus develops a detailed model of the production strategies associated with the formation of shell mound sites that occur around Albatross Bay, while also considering the broader significance of this model, particularly within the context of Cape York Peninsula. It presents the results of field surveys and excavations carried out around Albatross Bay by the author, as well as a detailed review and analysis of work carried out by others. It is argued that shell mounds are the result of relatively specialised production activities focussing on a very specific resource base: mudflat shellfish species. Shell mounds offered a range of unique benefits for people engaged in these specialised activities, including as camp sites and as specialised activity areas. These events were inherently flexible in size and in terms of timing, reflecting the dynamic nature of the resource base itself; yet the flexible nature of this production strategy also enabled more regular small scale social gatherings, along with a range of social and economic benefits to participants, than would have been otherwise possible. It is proposed that these types of strategies may represent an important characteristic of the production systems employed by gatherer-hunter peoples in late Holocene Cape York. Overall, this thesis makes a significant contribution to both our understanding of late Holocene lifeways at Albatross Bay as well as to our understanding of the broader significance of the emergence of shell mound sites in Cape York. Furthermore, it highlights the range of insights that can come from a focus on short-term modelling of gatherer-hunter lifeways alongside approaches oriented toward longer-term explanations of economic, social and environmental change.

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