Jinmium rock shelter is famous for the claims made by Fullugar et al. (19%) for the early human colonization and ancient rock art of northern Australia. These claims were based on thermoluminescence ages obtained for the artefact-bearing quartz sediments that form the JIoor deposit at the site. In this paper, we outline the background to the optical dating programme at Jinmiurn, 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. 1999, this volume).

We present a new analysis of parton distributions of the proton. This incorporates a wide range of new data, an improved treatment of heavy flavours and a reexamination of prompt photon production. The new set (MRST) shows systematic differences from previous sets of partons which can be identified with particular features of the new data and with improvements in the analysis. An 'explanation' of the behaviour seen on the Caldwell plot is offered.

We determine the parton distributions of the pion from a consistent next-to-leading-order analysis of several high-statistics T'N experiments including both Drell-Yan and prompt photon production.

We perform a global parton analysis of deep inelastic and related hard-scattering data, including O(α QED ) corrections to the parton evolution. Although the quality of the fit is essentially unchanged, there are two important physical consequences. First, the different DGLAP evolution of u and d type quarks introduces isospin violation, i.e. u p = d n , which is found to be unambiguously in the direction to reduce the NuTeV sin 2 θ W anomaly.A second consequence is the appearance of photon parton distributions γ(x, Q 2 ) of the proton and the neutron. In principle these can be measured at HERA via the deep inelastic scattering processes eN → eγX; our predictions are in agreement with the present data.

Although it is generally agreed that the Arctic flora is among the youngest and least diverse on Earth, the processes that shaped it are poorly understood. Here we present 50 thousand years (kyr) of Arctic vegetation history, derived from the first large-scale ancient DNA metabarcoding study of circumpolar plant diversity. For this interval we also explore nematode diversity as a proxy for modelling vegetation cover and soil quality, and diets of herbivorous megafaunal mammals, many of which became extinct around 10 kyr bp (before present). For much of the period investigated, Arctic vegetation consisted of dry steppe-tundra dominated by forbs (non-graminoid herbaceous vascular plants). During the Last Glacial Maximum (25-15 kyr bp), diversity declined markedly, although forbs remained dominant. Much changed after 10 kyr bp, with the appearance of moist tundra dominated by woody plants and graminoids. Our analyses indicate that both graminoids and forbs would have featured in megafaunal diets. As such, our findings question the predominance of a Late Quaternary graminoid-dominated Arctic mammoth steppe.