A Thermal Adventure–Part 2–The Big One!

On April 15^th, the first day we could return to Yellowstone on which the West entrance would be open, the first thing the kids wanted to see was Old Faithful. We had about an hour drive from where we were staying and wanted to get an early start to make the most of our day. We arrive at Yellowstone at 9:24 am and all are excited! Old Faithful did not disappoint us, erupting a mere 15 minutes after our arrival. Of course that was only the first of our observations of her eruptions that day.

To distinguish between the Mammouth Hot Springs we had seen a few days earlier, which are beautiful if a bit less ostentatious than their thermal cousins, a geyser is a hot spring with the unique habit of tossing underground water into the air. To begin the process, water, falling as rain or snow seeps through porous layers of rock and eventually comes into contact with the extremely hot rocks below the surface that have been heated by the large body of molten material, called magma, that exists below the surface of the Park.

This (now) hot water then rises through a series of cracks and fissures underneath the surface of the Earth. These fissures are like the “plumbing system” of a thermal feature in that a geyser is like a giant pressure cooker.

Though the temperature of water at the deepest level may be well above boiling, the weight of the water on top prevents it from boiling for awhile. Eventually, however, the pressure builds enough to push the water in the upper reaches up and out an overflow, which relieves the pressure on the super-heated water below, causing it to flash into steam. That flash or explosion through a narrow constricted place in the rocks is what sends water shooting into the air.

The kids just couldn’t get enough of watching the geysers erupt and spent the entire day walking from one to the other to see if anything was happening, afraid they would miss something. I lost count of the number of times they watched Old Faithful spout off. We also photographed numerous geysers; some of the more memorable include Old Faithful, of course, but also Beehive and Giant Geysers. Terry and I enjoyed this day as much as the kids, both experiencing this amazing phenomenon for the first time and watching them enjoy it as well. It was clearly worth a second trip! It was only a bit later on that we began to explore a few other thermal features in the Park that had largely gone unnoticed in our first infatuation with the showy geysers, but that will have to be the subject of another post….

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