It should be noted there exists an alternate theory for the final explosion: Overpressurization of the magma chamber. Some evidence suggests that Krakatoa's magma chamber may have been infused with newer, hotter magma, during the course of the event; as a result, the hotter magma may have expelled gas dissolved within the cooler magma and created an unsustainable level of pressure, leading to a cataclysmic explosion. Evidence for this theory is the existence of pumice consisting of light and dark material, the dark material being of much hotter origin.