YELLOWSTONE NATIONAL PARK — In this week’s Caldera Chronicles, the scientists of Yellowstone Volcano Observatory (YVO) discuss the common misconceptions regarding what makes the Yellowstone National Park (YNP) hot springs so dangerous.
The weekly column is written by the scientists and collaborators of YVO. This week’s edition, written by YVO’s Scientist-in-Charge Michael Poland, shows how the recent death of a bison in Grand Prismatic Hot Spring is an unmistakable example of the dangers found in the park’s thermal areas.
According to the column, on the morning of Saturday, June 21, visitors witnessed a bison step into the shallow part of the hot spring. The animal appeared alarmed by the temperature of the water — about 192 °F, which is just below boiling at that elevation — and stumbled trying to get out. The bison stepped into a deeper part of the pool and quickly died.
The column states that YNP officials did not remove the carcass because that could have caused extensive damage to the colorful floors that give Grand Prismatic its name. Although rarely observed, animals can and do fall into hot springs.
“Animals can obviously feel the heat of thermal areas through their feet or hooves,” wrote Poland, “but that doesn’t necessarily mean they never make mistakes near hydrothermal features.”
Many park visitors believe a common misconception about the hot springs: that they are acidic and will cause an acid burn on contact, which will dissolve any animals or people that fall into the springs. Poland clears up this notion by saying the hot springs and geysers are almost all neutral or alkaline (having a pH of 7 or greater). The acidic features in the park (pH lower than 5) tend to be fumaroles (gas vents), mud pots and frying pans, which are dominated by the release of acidic gases. The acid concentrations in those features are low, and would not burn on contact, although they can cause skin irritation.
The reason animals and occasionally people who fall into hot springs are killed is not acidity, but simply temperature. With many of the hot springs near boiling temperatures, animal life cannot survive for long when exposed to water that hot.
The unfortunate death of the bison in Grand Prismatic is an important example of why it is required to stay on the boardwalks in thermal areas of YNP. Thermal areas have thin crusts that can easily be broken through. What lies below could just be a pool of boiling water.
