Yellowstone National Park Visit      July - August 2003 Thermal Pool

A visit to Yellowstone makes me wish I had paid better attention in my geology class in undergrad school.  We did attend a lecture by a geologist who explained the difference and similarities of the many thermals.  We learned about geysers, hot springs, sulfur pools and fumaroles.  These wonderful features all exist because Yellowstone sits in a caldera of a volcano which still has molten rock just below the earth’s surface.  Frequent earthquakes change some of the features periodically, but the molten rock continues to do its job.  The geologist pointed out that the volcano erupted every 600 to 700 thousand years, and it has been about 600 thousand years since the last one, so we might expect one in the next thousand years.  We decided not to worry about it and went on to enjoy the park.