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This reconnaissance study of radon concentrations in the Great Cave of Niah in Sarawak shows that in relatively deep pits and trenches in surficial deposits largely covered by protective shelters with poor ventilation, excavators are working in a micro-environment in which radon concentrations at the ground surface can exceed those of the surrounding area by a factor of >×2. Although radon concentrations in this famous cave are low by world standards (alpha track-etch results ranging from 100 to 3075 Bq m-3), they still may pose a health risk to both excavators (personal dosemeter readings varied from 0.368 to 0.857 mSv for 60 days of work) and cave occupants (1 yr exposure at 15 h per day with an average radon level of 608 Bq m-3 giving a dose of 26.42 mSv). The data here presented also demonstrate that there is considerable local variation in radon levels in such environments as these. [Copyright &y& Elsevier]

Abstract In desert dune environments, vegetation may be an indicator of dune stability and rates of sediment transport. As topography and underlying controls of vegetation vary over large spatial areas, variations in dune form make scaling up of field research difficult. To mitigate this, and to identify spatial variations in vegetation distributions in a Saudi Arabian sand sea, spectral information from high resolution satellite images was classified to map polygons of shrub vegetation over 360 km2 of well-defined linear dunes, broken linear dunes and dome dune forms. When compared to topographic characteristics of the landscape, extracted from a digital elevation model, vegetation densities were often highest on 10–20° slopes elevated above interdune salt deposits on dune flanks. Spatially this was confined to small areas, and density was not always related to dune form, more to access of groundwater which encouraged colonisation on the tops of some dunes. Field observations identified shrubs of mainly Calligonum genus whose size is related to the amounts of salts, moving sediment, and access to the water table that varies within and between dune forms. Shrub density is likened to surface roughness (z 0) to better understand sediment movement and modelling in dunes. Highlights • High res. satellite images detect shrubs across linear, dome dunes and interdunes. • Greatest densities of shrub vegetation are found on 10–20-degree slopes. • Shrubs that colonise tops of dunes indicate groundwater is present and accessible. • Character of interdune shrubs are affected by evaporite salts and wind intensity. • Mapping density, or surface roughness, can be helpful for modelling. [ABSTRACT FROM AUTHOR]

Abstract: Recent research in Europe, Africa, and Southeast Asia suggests that we can no longer assume a direct and exclusive link between anatomically modern humans and behavioral modernity (the ‘human revolution’), and assume that the presence of either one implies the presence of the other: discussions of the emergence of cultural complexity have to proceed with greater scrutiny of the evidence on a site-by-site basis to establish secure associations between the archaeology present there and the hominins who created it. This paper presents one such case study: Niah Cave in Sarawak on the island of Borneo, famous for the discovery in 1958 in the West Mouth of the Great Cave of a modern human skull, the ‘Deep Skull,’ controversially associated with radiocarbon dates of ca. 40,000 years before the present. A new chronostratigraphy has been developed through a re-investigation of the lithostratigraphy left by the earlier excavations, AMS-dating using three different comparative pre-treatments including ABOX of charcoal, and U-series using the Diffusion-Absorption model applied to fragments of bones from the Deep Skull itself. Stratigraphic reasons for earlier uncertainties about the antiquity of the skull are examined, and it is shown not to be an ‘intrusive’ artifact. It was probably excavated from fluvial-pond-desiccation deposits that accumulated episodically in a shallow basin immediately behind the cave entrance lip, in a climate that ranged from times of comparative aridity with complete desiccation, to episodes of greater surface wetness, changes attributed to regional climatic fluctuations. Vegetation outside the cave varied significantly over time, including wet lowland forest, montane forest, savannah, and grassland. The new dates and the lithostratigraphy relate the Deep Skull to evidence of episodes of human activity that range in date from ca. 46,000 to ca. 34,000 years ago. Initial investigations of sediment scorching, pollen, palynomorphs, phytoliths, plant macrofossils, and starch grains recovered from existing exposures, and of vertebrates from the current and the earlier excavations, suggest that human foraging during these times was marked by habitat-tailored hunting technologies, the collection and processing of toxic plants for consumption, and, perhaps, the use of fire at some forest-edges. The Niah evidence demonstrates the sophisticated nature of the subsistence behavior developed by modern humans to exploit the tropical environments that they encountered in Southeast Asia, including rainforest. [Copyright &y& Elsevier]