From Wood and Kienle (1990): "Andesitic
pyroclastic flows sampled at a seismic station (Adak network) are indicative of explosive eruptions; lavas at the same site indicate that more quiescent extrusive activity also occurred. Texturally, the rocks resemble those of Moffet
volcano 50 km to the east. The geology of this small island and the timing of its volcanism are unknown."