there are only a few supervolcanoes in the world and yellowstone park in the usa is one of them.the volcano ... nearly every 600,000 years and just before it does,there are large ... in the area.the thick black ash that falls from the huge ... kills most of the plant life,and many species find it difficult to ... it also ... light from the sun and there is a drastic ... in temperature,making it feel like winter across the globe. if scientists are correct,and yellowstone's supervolcano is ready to wake up,then humans may become ... too