We're standing at one of the display springs at Hot Springs National Park. My name is Steve Rudd and I'm the Natural Resources Program Manager here at the park. One of the most commonly asked questions by park visitors is where the heat comes from in the geothermal springs. A lot folks have traveled in western parks and other parts of the world, and they've seen geothermal springs in those places. Those locations are producing steam, which is much hotter than what is coming out of the ground here and it's volcanic in origin. And that sets us apart from all the rest. The water here has no volcanic component at all and it's heated completely through conduction or contact with parent rock material that's very deep in the earth. Now how deep is deep? We think that this water is plunging to a depth of around seven, maybe eight thousand feet before it makes its way back to the surface, and we think that happens very quickly. And the rate at which the temperature heats up with depth is predictable. Geologists call this a geothermal gradient. In most situations, it's approximately one degree Centigrade per hundred feet of depth. Now, that changes depending on rock type and geology and your base altitude or elevation, but it's a pretty universal constant. The water that you're seeing here comes out of the ground at about an average temperature of 140 degrees Fahrenheit or 61 degrees Centigrade. The reason it has no odor and doesn't have a taste is that there's a general lack of sulfur compounds that are common with volcanic heat sources. That's one of the reasons this water is so pleasant to be around, be in, consume. This is the only place in the [National Park] System that offers geothermal water as a potable water supply. |
Last updated: April 10, 2015