THIS note reports measurements made in an attempt to determine: (1) the possible effect of xenoliths on whole-rock basalt age determinations; (2) whether or not potassium-argon age determinations on xenoliths in basalt might approximate the age of the basalt flow. The field location is in the canyon of Sawmill Creek, Inyo County, sec. 7 md 18, T. 12 S., R. 34 E., and sec. 12 and 13, T. 12 S., R. 33 E.