(Table 3) Average trace-element composition of glass shards from Toba Tephra Beds in Sumatra, Malaysia, India, and the Indian Ocean

Positions are estimated from map. Samples were analyzed at the University of Wales, Aberystwyth. Fully quantitative solution ICP-MS analyses were performed using a VG Elemental ICP-MS PlasmaQuad II/ with a modified high sensitivity interface and calibration was achieved using multi-element synthetic standards. Details of the analytical procedures and standards are given in Pearce et al. (1997). Concentration reported is the average of five analyses of the same solution. Relative standard deviations for rare-earth elements are less than 1% and most of the other trace elements have RSDs less than 5%.