CONCLUSIONS

During Leg 172, we recovered paleomagnetic records of 14 "plausible" magnetic field excursions at Sites 1060-1063 spanning more than 1200 km. New U-channel paleomagnetic studies of all 14 excursions indicate that 12 do contain true excursional directions, but five still require discrete sample paleomagnetic measurements to further verify their reality. U-channel measurements for two of the original 14 "plausible" excursions (3, 5) did not show evidence of true excursional directions and are no longer considered to be real. U-channel measurements also identified one new excursion not identified during shipboard measurements. We also identified other types of anomalous directional variability that we currently think may be due to systematic biases in the long-core and U-channel measurement process. Further study using discrete samples will be necessary to resolve such uncertainties. All of these observations suggest that excursions are not rare, random perturbations of the stable geomagnetic field, but rather an important systematic and distinct component of the Earth's magnetic field variability between field reversals.