K-Ar and fission-track dating of ash partings in coal beds from the Kenai Peninsula, Alaska: A revised age for the Homerian Stage–Clamgulchian Stage boundary

K-Ar and fission-track mineral ages determined from ash partings in upper Tertiary coal beds from the Kenai Peninsula, Alaska, establish an age of approximately 8 m.y. (late Miocene) for the Homerian Stage–Clamgulchian Stage boundary at the type section for the Homerian Stage and a late Miocene age for the early part of the Clamgulchian Stage. Our data do not support the concept that there is an “Arcto-Tertiary geoflora” which is different in age from similar floras at lower latitudes.

This study demonstrates, for the first time, that volcanic ash partings contained wholly within coals are valuable for radiometric dating and stratigraphic correlation.