Extended Data Fig. 9: Directional data from the H50 ash layer.

(a) Representative example of orthogonal NRM demagnetization diagram of a specimen from block C1 (white layer from H50) and its respective normalized intensity decay plot. Symbols as in Extended Data Fig. 7. (b) Equal area projection of the mean direction of ChRM (related to the burning event), along with their respective α₉₅ (circle of confidence at 95% probability; p = 0.05)_, calculated with specimens from block C1 (yellow; 9 specimens from 1 oriented block; k = 133.2; α₉₅ = 4.5°) vs. direction calculated with H50 specimens selected for the final direction (blue; 9 specimens from 1 oriented block; k = 105.9; α₉₅ = 5.0°). Directions for individual specimens are also shown (lighter colored symbols). C1 specimens are affected by flattening (see Supplementary Methods 1). Solid symbols represent downward inclination. NRM values are normalized by the estimation of specimens’ mass excluding plaster content. (WL = White Layer). Calculations of mean directions are based on Fisher’s statistics⁴¹. Thermal demagnetization of Natural Remanent Magnetization (NRM) is performed only once on each specimen due to the irreversible character of the experiment (it causes the progressive destruction of the original NRM). For this reason, a minimum of 8 specimens per hearth was demagnetized to obtain directional data. Specimens shown here correspond to those accepted after filtering (Supplementary Methods 1).