K-A age

K-A age

[′kā′ā′ ‚āj]
(geology)
The radioactive age of a rock determined from the ratio of potassium-40 (40K) to argon-40 (40A) present in the rock.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.