Here's just one of many examples of the vast 'geothermal' activity that is part of Yellowstone. Hot bubbling pools and geysers... all heated by magma below the earth's surface. The Yellowstone Caldera is the largest volcanic system in North America. And what's cool is the series of boardwalks that allow you to walk among and see up close this activity... like my first time in 1972.

July 29, 2005 | Sights along the way 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13