What is a Radioisotope Age?
The radioisotope age of a specimen is obtained from a calculation of the time that would be required for unstable parent atoms [P] to spontaneously convert to daughter atoms [D] in sufficient amount to account for the present D/P ratio in the specimen. For the dating of Lucy, P was the unstable isotope 40 of potassium [40K] and D was the stable isotope 40 of argon [40Ar]. Conflicting Data Lava from the AD 1901 eruption of Hualalei in Hawaii has potassium-argon (K-Ar) ages as great as 1.1 billion years. Historic eruptions of Mt. Kilauea in Hawaii have produced submarine lavas with K-Ar ages as great as 43 million years. Obviously these K-Ar ages do not represent the time of eruption, or the age of the lava flows. The ages must reflect other characteristics of the lava. K-Ar ages from a volcanic deposit at Katmai, Alaska suggest volcanic activity four million years ago. Historical records establish that the eruption which produced these deposits occurred in AD 1912. A dominant feature of
