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Dating glacial and associated sediments is essential to provide a temporal framework for accurate reconstructions of past climatic conditions and for helping to determine the nature and magnitude of glaciation for landscape evolution studies. There are few widely applicable, accurate and precise methods available to date Quaternary landforms and sediments, despite the numerous numerical dating methods that are currently available. Furthermore, there are few methods that can be utilized for the whole of the late Quaternary (c. 125 kyr ago to present). Recent developments in luminescence dating, however, are providing opportunities to date a broad range of late Quaternary glacial and associated landform sediments. The application of luminescence methods requires an understanding of the nature of glacial and associated environments to select the most appropriate sediment samples for dating. Problems associated with luminescence dating of glacial sediments include insufficient bleaching, low sensitivity of quartz, and variable dose rates during the history of the sediment due to changing water content or nuclide leaching. These problems can be overcome by careful sampling and descriptions of the sampling site, testing for insufficient bleaching and modelling dose rate variability.

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Net proton and negative hadron spectra for central Pb 1 Pb collisions at 158 GeV per nucleon at the CERN Super Proton Synchrotron were measured and compared to spectra from lighter systems. Net baryon distributions were derived from those of net protons. Stopping (rapidity shift with respect to the beam) and mean transverse momentum ͗ p T ͘ of net baryons increase with system size. The rapidity density of negative hadrons scales with the number of participant nucleons for nuclear collisions, whereas their ͗ p T ͘ is independent of system size. The ͗ p T ͘ dependence upon particle mass and system size is consistent with larger transverse flow velocity at midrapidity for Pb 1 Pb compared to S 1 S central collisions. Lattice QCD predicts that strongly interacting matter at an energy density greater than 1 2 GeV͞fm 3 attains a deconfined and approximately chirally restored state known as the quark-gluon plasma (for an overview, see [1]). This state of matter existed in the early Universe, and it may influence the dynamics of rotating neutron stars [2]. The collision of nuclei at ultrarelativistic energies offers the possibility in the laboratory of creating strongly interacting matter at sufficiently high energy density to form a quark-gluon plasma [3]. Hadronic spectra from these reactions reflect the dynamics of the hot and dense zone formed in the collision. The baryon density, established 0031-9007͞99͞82(12)͞2471(5)$15.00

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