Fig. 3. The ¹⁴C-derived chronology for the Draper, Spang, and Mantle sites with each site modeled as an independent phase.

(A) The OxCal (32, 35) model for each of the three site Phases (Draper, Spang, and Mantle) using IntCal13 (34). All the data in table S1 except those four dates with suspect δ¹³C values are included. The Charcoal Outlier model is specified for the wood charcoal samples (35), and the General Outlier model (35) is specified for all other materials. Compare results using the modified Charcoal Plus Outlier model (30, 37) in fig. S6. The OxCal agreement indices both indicate good agreement between the data and the model (A_model = 96.4 and A_overall = 93.5, both >60). There are still a few minor possible outliers: compare with the results in fig. S7. The nonmodeled calibrated dating probabilities are indicated by the light gray distributions; the modeled probabilities are shown by the smaller black distributions. The lines under these modeled distributions indicate the 95.4% hpd ranges. (B) The modeled Date estimates for the Draper, Spang, and Mantle sites are shown in detail and compared with the currently accepted date estimates (“current date”) for each site (3, 14).