10 research outputs found
Multiple influences on regolith characteristics from continental-scale geophysical and mineralogical remote sensing data using Self-Organizing Maps
We investigate the characteristics of regolith through the application of statistical learning to diverse layers of terrestrial, continental-scale remote sensing data. This combination allows us to explore the multiple influences of bedrock, climate, biota, landscape and time on regolith development and properties: an interdisciplinary geoscience modeling problem. From a wide variety of available data for Australia, we select remotely sensed geophysical, geomorphological and mineralogical inputs with good spatial coverage. We use Self-Organizing Maps (SOM), a topologically constrained unsupervised statistical learning algorithm, to characterize the geophysical and mineralogical signatures of regolith and bedrock. Regolith materials cover more than 80% of the Australian continent, range in age from Precambrian to Quaternary and vary in thickness from less than a meter to more than a kilometer. The diversity of regolith cover type and character across Australia provides an opportunity to demonstrate knowledge discovery from remote sensing data. The outputs of our SOM analysis are combined with ground observations from locations showing naturally occurring anomalous concentrations of nickel, tin and uranium. We identify a minimum number of natural clusters indicating subtle but significant differences in regolith and bedrock mineralization characteristics. Our results show that SOM identifies spatially contiguous regions representing unique regolith and bedrock materials. In the Yilgarn Craton we observe key differences in landscape character, density of the crust, and relative abundance of radioactive elements and alumino-silicate and ferric oxide minerals. These properties discriminate between nickel-prospective residual deeply weathered regolith formed on mafic and/or ultramafic bedrock and uranium-prospective Cainozoic paleochannels containing felsic bedrock source materials. National-scale data are publicly available for many continental regions, as in the Australian example, and our approach has general applicability. We demonstrate that remote sensing data may be used to understand the regolith, revealing the interplay between environmental history and bedrock character at regional scales, and differences between residual and transported regolith, provenance of source materials and their relative ages
Multiple influences on regolith characteristics from continental-scale geophysical and mineralogical remote sensing data using Self-Organizing Maps
A Simulation-Based Methodology for Analyzing Congestion and Emissions on a Transportation Network
Expansion of landscape characterisation methods within the Hydrogeological Landscape Framework: application in the Australian Capital Territory
Mechanical properties, ductility, and grain size of nanocrystalline iron produced by mechanical attrition
Samian Pottery in Britain: Exploring its Distribution and Archaeological Potential
This paper presents some of the results of an English Heritage funded study of the distribution of samian pottery (Terra Sigillata). It aims to highlight the value of samian pottery as a resource for exploring a range of archaeological questions beyond its essential role in providing dating evidence. The work to date has comprised a pilot study designed to assemble an initial database of stratified samian groups, to test methodologies and to explore the character of samian distribution. Some substantive patterns identified from the database are reproduced here and discussed. The opportunity is also taken to clarify baseline trends in the occurrence of samian within Roman pottery assemblages, and to place patterns in the incidence of this ware within the wider context of Roman Britain. A number of other aspects of archaeological value, for instance, the nature of samian from rural sites and the potential use of samian in ritual actions, are also evaluated. A written report and (hardcopy) database were produced in 1997 (Willis 1997b), which presented the results of phase 1 of the survey, with approximately 50 copies circulated for comment. The middle section of the present paper draws on this report. It is hoped that in due course the database will be accessible to all potential users (including excavators, students, curators and academics), for the comparison of samian assemblages from different sites. The database should establish whether there are ‘normal patterns’ of samian occurrence/supply, by region, time, and site type, against which individual site assemblages may be compared.
The focus of the pilot study, being funded by English Heritage, has been upon sites within England. However, evidence from sites in Wales and Scotland, both military and civilian, has equal relevance constituting important comparative data. Samian assemblages from these parts of Britain are hence included in the current discussion. Considering the larger canvas, samian work in Britain is part of an international context of study, of what was a widely distributed and imitated material. Specialists in Britain are closely networked with workers elsewhere in western Europe. One of the most fruitful aspects of this liaison is the potential for identifying similarities and differences in the incidence of samian from region to region. It is hoped that the present paper, identifying trends in the British evidence, can contribute to inter-provincial comparisons.
This paper has four principal sections. First, the background to the project is outlined, with previous quantitative and comparative studies of samian noted. The second section deals with broad aspects of samian distribution, considering its status during the Roman era, its geographic incidence and its occurrence as a component of pottery groups. Trends in the occurrence of samian types are then examined, while in the final components several areas of special interest are explored. The concluding sections emphasize the main findings and outline the prospects for future work; the manner in which samian information is published in reports is also considered