K-Ar age of the late Pleistocene eruption of Toba, north Sumatra

The late Pleistocene eruption of Toba is the largest magnitude explosive eruption documented from the Quaternary. K-Ar dating of the uppermost unit of the Toba Tuff gives an age of ~ 75,000 yr. A chemically and petrographically equivalent ash layer in deep-sea cores helps calibrate the Stage 4-5 boundary of the standard oxygen isotope stratigraphy. A similar ash in Malaya that overlies finds of Tampan Palaeolithic tools indicates that they are older than 75,000 yr.