Fig. 1. Map showing Blombos Cave, Die Kelders, Klasies River, Pinnacle Point, and Bredasdorp. The bathymetry is from Van Andel (1989).

Fig. 2. (a) General view of the south and east sections showing the position of some, but not all, samples for dating. Sample ZBroofB was taken from the block visible below ZB6. (b) Layout of cave showing excavation grid, with red indicating area from which samples were taken. (c) Close-up photo of the south section (square G6), with the M1, M2, and M3 phases indicated alongside photos of some of the more significant finds.

Fig. 3. Photos of (a) layer with small pieces of roof spall, which provide an unconformity that separates phases M2 and M3 (square H5d), and (b) after excavation that reveals layer CH/CI of phase M3, containing archaeological material, including shells.

Fig. 4. Data for single aliquots (2 mm in diameter) of sand (ZB9) overlying the LSA deposits: (a) OSL decay curves for the natural dose (L_N) and a laboratory dose (L_X) of 0.16 Gy; (b) standardized dose-response curve showing derivation of D_e; and (c) radial plot giving D_e values for 24 aliquots.

Fig. 5. Data for a single aliquot (2 mm in diameter) of quartz grains from the block of roof spall (ZBroofB): (a) OSL decay curve for natural dose (note low count rate); and (b) standardized dose-response curve showing the natural signal to be at the saturation level, as determined using very high regenerative doses.

Fig. 6. Radial plots for single grains of ZB15 that had been bleached and then given doses of (a) 52 Gy and (b) 4.8 Gy and (c) for the combined data sets. The open symbols relate to D_e values outside the ±2σ range.

Fig. 7. Radial plots of D_e distributions for single aliquots of (a) 5-mm and (b) 2-mm mask size, and (c) for single grains for ZB4.

Fig. 8. Radial plots of D_e distributions for single aliquots of (a) 5-mm and (b) 2-mm mask size, and (c) for single grains for ZB10.

Fig. 9. Radial plots of D_e distributions for single aliquots of (a) 5-mm and (b) 2-mm mask size, and (c) for single grains for ZB7.

Fig. 10. Radial plots of D_e distributions for single aliquots of (a) 5-mm and (b) 2-mm mask size, and (c) for single grains for ZB8.

Fig. 11. Radial plots of D_e distributions for single aliquots of (a) 5-mm and (b) 2-mm mask size, and (c) for single grains for ZB6.

Fig. 12. Radial plots of D_e distributions for single aliquots of (a) 5-mm and (b) 2-mm mask size, and (c) for single grains for ZB42.

Fig. 13. Radial plots of D_e distributions for single aliquots of (a) 5-mm and (b) 2-mm mask size for ZB5.

Fig. 14. Data for a single aliquot (5 mm in diameter) of quartz grains from ZB8: (a) OSL decay curve for natural dose (note high count rate) and (b) standardized dose-response curve.

Fig. 15. Radial plots for (a) ZB7, (b) ZB8, and (c) ZB42 showing the two (a,c) and three (b) populations of grains identified by applying the finite mixture model. The central age model was then applied to each population.

Fig. 16. Daughter/parent radionuclide-activity ratios for geological samples (above dotted line) and MSA samples (below dotted line). Data for ZB42 are not shown, as this sample was not measured using high-resolution gamma spectrometry.

Fig. 17. Sea level curve (after Pillans et al., 1998) showing oxygen isotope stages and stage 5 substages, with OSL ages and schematic section. The OSL ages were calculated using single-grain results for all samples except ZB9 (5-mm aliquots) and ZB5 (2-mm aliquots).

Information on number of subsamples measured (a) using 5-mm-diameter aliquots, (b) using 2-mm-diameter aliquots, and (c) using single grains. The number of rejected D_e values given and the value of the D_e calculated by applying the central age model to the full data set, together with the value of overdispersion

Dose rates, D_e values, and derived OSL ages. D_e values are derived from single grains for all samples, except ZB9 (5 mm) and ZB5 (2 mm). For single-grain D_e values, the central age model data from Table 1c were used, apart from the values for ZB7, ZB8, and ZB42, for which the finite mixture model data were used, as discussed in the text

Parent isotope activities obtained from high-resolution gamma spectrometry for all dated samples from inside the cave

Notes: Data for ZB42 are from TSAC and XRF. Data are also given for ZB20 and ZBroof.