OPTICAL DATING OF SINGLE AND MULTIPLE GRAINS OF QUARTZ FROM JINMIUM ROCK SHELTER,NORTHERN AUSTRALIA: PART I,EXPERIMENTAL DESIGN AND STATISTICAL MODELS*

Jinmium rock shelter is famous for the claims made by Fullagar et al. (1996) for the early human colonization and ancient rock art of northern Australia. These claims were based on thermo-luminescence ages obtained for the artefact-bearing quartz sediments that form the floor deposit at the site. In this paper, we outline the background to the optical dating programme at Jinmium, and describe the experimental design and statistical methods used to obtain optical ages from single grains of quartz sand. The results, interpretations, and implications of this dating programme are reported in a companion paper (Roberts et al. 7999, this volume).     

Biodiversity and Nature Conservation: Some Common Arguments and Alternative Views

Abstract

The impact of human activities on the environment is perhaps now reaching its greatest level of awareness in human history. There is concern regarding health effects of pollutants generated by industry, climate change related to burning of fossil fuels and effects of anthropogenic activities in terms of promoting the extinction of biological species. Proposals are being put forward at local, national and international levels to preserve biodiversity. It is commonly believed that human activities, if not controlled, will lead to dramatic decreases in the earth's biodiversity. In this report, temporal perspectives of biodiversity (e.g. from palaeontology) are emphasized both as reasons for conservation and as possible errors of reasoning in conservation debates. Questions and novel implications related to an integral view of humans as a part of nature are also presented in the context of related environmental issues.     

OPTICAL DATING OF ANTHROPOGENIC SEDIMENTS AT THE ARCHAEOLOGICAL SITE OF HERRENBRUNNENBUCKEL,BRETTEN-BAUERBACH (GERMANY)*

Optical dating was applied to natural and anthropogenic silts at an Iron Age settlement in southern Germany. The natural sediments were dated accurately and allowed study of the human impact on the landscape. The studied anthropogenic sediments were infills of cellars and ditches. Again, deposits derived from soil erosion proved to be datable using infrared-optically stimulated luminescence. However, optical dating of fine grained sediments was at its limits when sediments consisted of a mixture of bleached and unbleached grains. This is shown on sediments of known age originating from cellar infills. Improvements were obtained when using the 560 nm emission and a partial bleach approach. Experimental evidence shows that the D_E versus shine-time plot discloses insufficient bleaching only in cases in which all grains are insufficiently bleached to the same degree.     

THE BRITISH ARCHAEOMAGNETIC CALIBRATION CURVE: AN OBJECTIVE TREATMENT

This paper examines the limitations and deficiencies of the current archaeomagnetic calibration curve in use in Britain and explores a different approach to its construction, drawing on recent advances in this subject, in particular the use of a weighted moving window method of averaging. The main advantage of this method is shown to be its ability to take into account uncertainties in both the magnetic direction and the archaeological date of data used in the calibration curve, leading to a secular variation curve with an associated error estimate. Hence, when dating a magnetic direction, the uncertainties in the calibration curve can be taken into account, as well as the uncertainties in the magnetic direction to be dated.     

MAPPING THE UNDISCOVERED RUINS OF POMPEII (NAPLES,ITALY) USING GROUND PENETRATING RADAR*

The ground penetrating radar (GPR) technique was tested in Pompeii, in an unexplored area where the Roman ruins are partially buried in the volcanic deposits. The method was also combined with time domain reflectometry (TDR) measurements to estimate the dielectric properties of the different volcanic units. In spite of the total thickness of the covering materials and the high signal attenuation measured in some layers, the radar was able to show a detailed image of the volcanic sediments and to locate the manmade structures hidden in the ash deposits. Moreover, the present study shows that the integrated use of GPR and TDR techniques could be successfully employed to evaluate the performance of the radar in specific terrains covering archaeological sites. Since it is unlikely that a large part of Pompeii will ever be excavated, GPR could be successfully used to produce detailed maps of the ruins still hidden in the subsurface, giving archaeologists the possibility of reconstructing the entire urban development of this unique ancient city.     

Identifying Chemical Activity Residues on Prehistoric House Floors: A Methodology And Rationale For Multi‐Elemental Characterization of a Mild Acid Extract of Anthropogenic Sediments

Archaeologists have employed sediment chemistry in site prospection for nearly a century. For example, phosphorus is a good indicator of human occupation, because it is a generic indicator of human activity. Recently, multi‐element studies of sediments have successfully identified specific activity areas by analysing other elements in addition to phosphorus. To reach its full potential, however, sediment chemistry must be undertaken with an understanding of how these residues are formed and of the chemical indicators that can be used to identify specific activities. Methodologies that optimize the extraction of specific residues must be employed. Not to do so is a naïve application of the technique.     

POTENTIAL MAGNETIC SUSCEPTIBILITY AND FRACTIONAL CONVERSION STUDIES OF ARCHAEOLOGICAL SOILS AND SEDIMENTS*

Potential magnetic susceptibility (χ_MAX) and, hence, fractional conversion (χ_CONV) are shown to be critical in interpreting low‐frequency mass‐specific magnetic susceptibility (χ_LF) data. Results presented from 29 sites in the UK and one in Hungary encompass six types of investigation: Quaternary sedimentary stratigraphies, archaeological contexts, surveys of old ground surfaces, topsoil surveys of lithic scatter sites, topsoil prospection surveys and ‘natural’ topsoils. The findings highlight the wide range of χ_MAX values that may be encountered; identify factors affecting χ_MAX; demonstrate that χ_CONV provides a measure of enhancement resulting from burning; and identify environments in which χ_LF analysis is likely to be problematic.     

LAND USE IN THE EASTERN ALPS DURING THE BRONZE AGE—AN ARCHAEOBOTANICAL CASE STUDY OF A HILLTOP SETTLEMENT IN THE MONTAFON (WESTERN AUSTRIA)*

Investigations of the oldest prehistoric settlement in the western Austrian county of the Vorarlberg reveal a deeper insight into the colonization of the Alps. The human presence is recorded from the Late Neolithic (c. 3000 cal. bc ) onwards, reflecting farming and possible mining activities. Three distinct settlement phases are recognized palynologically: (1) in the Early and Middle Bronze Ages (c. 1700 cal. bc ), (2) during the Iron Age (c. 500 cal. bc ) and (3) at the beginning of the medieval era (c. cal. ad 800). In addition plant macrofossil analyses of soil samples from the archaeological excavation of the Bronze Age settlement of Friaga indicate a complex subsistence strategy of the Middle Bronze Age settlers, whereby cereals and pulses reveal a balanced diet.     

The Potential for Dating the Old Scatness Site,Shetland, By Optically Stimulated Luminescence

A series of deposits from the agricultural infield of the multiperiod settlement mound, Old Scatness, were investigated for their potential to yield optically stimulated luminescence dates. Luminescence properties of quartz grains were found to vary through the sequence, but dates were successfully obtained from five deposits, including anthropogenic soils, windblown sands and sands within midden deposits. Single‐aliquot equivalent dose measurement was found to be the most appropriate method for dating the deposits. The OSL dates obtained accorded well with the dates provided by archaeological evidence and included the post‐medieval, Iron Age, Bronze Age and Neolithic periods of Shetland, while a substantial midden was dated to the Bronze/Iron Age transition.     

OPTICAL DATING OF SINGLE AND MULTIPLE GRAINS OF QUARTZ FROM JINMIUM ROCK SHELTER,NORTHERN AUSTRALIA: PART II,RESULTS AND IMPLICATIONS*

Quartz sediments from the floor deposit at Jinmium rock shelter have been investigated using the multiple-grain and single-grain optical dating methods described by Galbraith et al. (1999, this volume). Here we present the results of this dating programme and argue that the artefact-bearing sediments were deposited within the last 10000 years. This time interval is consistent with the radiocarbon chronology but is much younger than previous claims for initial human occupation during the Pleistocene. Analysis of individual grains revealed also that the characteristic saturation doses of some grains are unusually high, which may permit dating of deposits older than a few hundred thousand years. Such grain-to-grain differences raise doubts, however, about the validity of using multiple-grain samples to investigate the phenomenology of quartz luminescence.