Geologists form Brigham Young University in Utah have found evidence of a massive supervolcano near the Utah-Nevada border. They say it erupted around 30 million years ago at some 5,000 times greater than the Mount S. Helens eruption in 1980. They measure deposits from the eruption at 13,000 feet thick. Talk about leaving a mark! They used several techniques to confirm its existence including radiometric dating and chemical analysis of minerals. They say it was such a large eruption that it would have blocked out the sun for a while and had a catastrophic impact on the mammals, reptiles, and plant life living on Earth at that time.