The magma that rests below Oregon's Mount Hood is cool, not bubbling hot, according to a study of crystals in lava that chart the volcano's temperature history. "This tells us that the standard state of magma for this system is that it can't be erupted. That means that having a magma that can erupt is a special condition. Our expectation is that there's a lot of volcanoes that behave this way," said geochemist Kari Cooper of the University of California at Davis. The study was published in Nature.