IN tudying tory of Yelloone National Park, BobCiansen of ted States Geological Survey became puzzled about somet,oddly,  troubled anyone before:  find t ime t Yelloone ure—t’s ed for all itsgeysers and oteamy features—and t volcanoes is t tty conspicuous. But Ciansen couldn’t find tone volcanoanyructure known as a caldera.

    Most of us, es in a symmetrical mound.

    t Parícutin in Mexico, a farmer artled tosee smoke rising from a patc  opped out at almost fourteen  andogeten trusivelyvisible volcanoes on Eart a fe. But ted type of volcano t doesn’t involve mountain building. t t open in a single migure, leaving be subsided pit,tin one obviously ype,but Ciansen couldn’t find the caldera anywhere.

    By coincidence just at time NASA decided to test some neude cameras bytaking pograpone, copies of o ties on tion t t make a nice bloors’ centers. As soon as Ciansen saos o spottually ta crater more ty miles across—mucoo o be perceived from any some time in t Yelloone must o humans.

    Yelloone, it turns out, is a supervolcano. It sits on top of an enormous  spot, areservoir of molten rock t rises from at least 125 miles do fromt spot is one’s vents, geysers,  springs, and popping mudpots. Beneat is about forty-five miles across—roug eig its t point. Imagine apile of tNt about t miles into to about t of t cirrus clouds, and you  visitors to Yellooneare sop of. t sucs on tabove ed Yelloone and about territory about1,700 feet  bleaclysm is pretty o Professor Bill