Yellowstone, Part I: Thermal Features

All I knew about Yellowstone before I got here was that it is home to the famed Old Faithful Geyser.  Upon arriving, I kept hearing the term "thermal feature," which struck me as amusingly formal. Whatever people meant by the phrase, it seemed that we have more stuff than just Old Faithful.

"Thermal Feature" is essentially a blanket term describing any sort of geothermal activity that brings hot water to the earth's surface.  Such phenomena include hot springs, mud pots, fumaroles (steam vents), and geysers.  They are fueled by the Yellowstone supervolcano - one of the largest active volcanos in the world.  The most recent eruption, 640,000 years ago, was 1000 times the size of the 1980 Mount St. Helens eruption.  The volcano forms a hotspot under the park, where the earth's crust is only several miles thick rather than the usual twenty to thirty miles.  

The heat, along with the right underground "plumbing," has created about 10,000 thermal features here - a greater concentration than anywhere else in the world (runners up include Iceland, New Zealand, and Kamchatka).  Yellowstone also has the majority of the earth's geysers, including Steamboat, whose 400 ft. eruptions make it the world's tallest active geyser.

People disregarded reports of the area from early trappers and mountain men as tall tales, but after a couple of formal expeditions surveying the region, in 1872 Congress made Yellowstone the world's first national park to preserve this outstanding collection of thermal features.

Above is a picture from Hilary's and my trip to Artist Paint Pots two weekends ago.  Below is Grand Prismatic, the largest hot spring in Yellowstone and the third largest in the world (the first two are in New Zealand).