Before I arrive at the crater, I cross the pumice desert. They hypothesize that this was originally a glacial valley that was filled with pumice by the pyroclastic flows that burst from Mt. Mazama, the name now applied to the 12,000 foot mountain that was blown apart approximately 7,700 years ago, leaving the crater behind. It's estimated that the eruption ejected 50 times more airborne dust and ash than Mt. St. Helens did in 1980.