This award is for support of a two year project to measure the Helium concentrations and isotope ratios, Potassium/Argon ratios, and Krypton 81 ages in ice from the GISP2 core. The helium program is a search for nulls and/or reversals of the Earth's magnetic field, which should leave a strong signal in the Helium 3 to Helium 4 ratios and the Helium 3 concentrations in ice core Helium. If a geomagnetic Helium event is recorded in the ice sheets, it will provide a world-wide traceable horizon in both Greenland and Antarctica, for model studies of ice flow and for chronology. The Potassium/Argon measurements are to study gravitational fractionation of gases in the firn. The Krypton 81 dating will provide one of the first absolute ages on the GISP2 core.