Yellowstone is a collapsed volcano, or a caldera that is about 35 miles by 45 miles in size - in this case a super volcano that is not dormant. A volcano builds mountains and can destroy vegetation and wildlife for miles around. Super volcanoes obliterate mountains and can change the world climate for many months as well as render entire species extinct. Geologists estimate that over the past 1.8 million years, the Yellowstone Volcano has exploded an average of every 630,000 years. It has been approximately that many years since this super volcano last erupted.

UM Department of Geography