Five core samples from a depth of 182 to 1899 m were studied in order to ascertain if any geologically sensible K‐Ar ages could be determined on such highly altered material. Ages were obtained ranging from 8.9 to 10.9 Ma, seemingly consistent with previous K‐Ar work on correlated updip surface exposures. Serious radiogenic argon depletions or total overprinting by the hydrothermal metamorphism were not observed.