I went there in 1984. I remember standing a pasture with a Ranger. He was pointing at the horizon around us telling us that the mountains we were looking at all around us was actually the rim of an ancient caldera.

After he told us that, I could visualize that we were indeed standing in a large crater/caldera.

I have heard Yellowstone may once again erupt, and such an eruption will effect the Earth’s climate, as it had done in the past.

BTW, If you want to read a great story about Yellowstone, read the Yellowstone story book, especially the part about the Washburn expedition. The Washburn expedition was a bunch of 1800’s businessmen being lead by a Amy lieutenant. It gets interesting when one of their members gets lost and has to survive on his own until he is found weeks later by a trapper.