Members of the Geochronology Lab use a laser or a furnace to melt grains of rock and release argon gas, which they can date using a mass spectrometer and the 40-argon/39-argon dating technique. They use this method to solve geological and geophysical mysteries in Alaska and elsewhere, including the eruptive history of Alaska’s volcanoes, the rate of uplift of Alaska’s mountains, and the tectonic history of Alaska and Russia. Lab users have dated fragments of stone-age tools in an attempt to find the sources of the tools and ancient trading patterns.