Each eruption has a distinct chemical signature that, along with conventional methods of carbon dating, can be used to associate each layer of volcanic material with a particular eruption. (scientificamerican.com)
Multiple episodes of volcanic material bubbling up from below may be needed to explain the features. (newscientist.com)
«That's an awful lot of volcanic material in one place for such a little planet,» Zuber said. (newscientist.com)