The PI will extend his Oligo-Miocene work on the recalibration of magnetic polarity time scale into the Late Cretaceous through Eocene interval. He will use spreading distances measured by finite rotation technique assuming relatively constant spreading rates at the ridge axes for million of years changing quickly to other constant rates. This assumption has been confirmed by the work on the last 10 million years, which has independent time scale calibration. Two to four intervals of apparent constant spreading on stable plate pairs is to be expected, with changes at time of tectonic reorganizations, such as the one at 6 Ma in the Pacific. Recalibration of the Paleogene geomagnetic polarity time scale is crucial to a better numerical time scale for the entire Cenozoic.
