Before this volcanic phase, Horizon Guyot had emerged from the sea and erosion had reworked some older rocks; also, plants grew on the now exposed island. Shallow water deposition in Coniacian (89.8 ± 0.3 – 86.3 ± 0.5 million years ago) or Santonian (86.3 ± 0.5 – 83.6 ± 0.2 million years ago) to Maastrichtian (72.1 ± 0.2 – 66 million years ago) time has been inferred from the presence of unstable coccoliths of such age in drill cores.
