Thermal Springs of Nevada

Author’s Note: This the first part of a weekly series on geology for a class I am taking this semester at BYU-Idaho. This week’s prompt is “Where have you seen geology in your daily life?” Other posts from this assignment can be found under the “Geology 111” category.

Geology, like weather, is all around us and has a profound influence on our daily activities. Sure, most geological processes seem to occur in the background without much day-to-day change, but when you look a little deeper it is clear that the Earth is alive and continues to change in subtle ways. Nevada is the perfect place to explore these processes because of the vast amount of public land.

Before I go on, I should admit that the featured image is a picture my wife took at a hot spring in Idaho. I don’t have any pictures on hand of any hot springs in Nevada since I’ve only lived here for a few months.

One daily influence of geology that stands out to me is the amount of geothermal energy in the state of Nevada. Nevada has more thermal springs (archive) than any other state in the Union. I say thermal springs rather than hot springs because a lot of them are ‘warm’ rather than ‘hot.’ Either way, Nevada has a lot of them.

I’m rather fond of visiting hot springs. Being on the college budget, I’m in no position to be buying a hot tub, plus I love adventures. Many of Nevada’s hot springs are down miles of gravel and dirt roads on land owned by the Bureau of Land Management. If you read my blog regularly, you might remember that my wife and I went out to the Black Rock Desert to watch the meteor shower (that blog post is located at this link).

To access the playa, we used Trego Hot Springs as a waypoint. We didn’t get in the water because the air was 10°F, but it was kind of eerie to watch steam rise from the water. Dipping a finger in revealed that the water was about the temperature of your standard-issue bath, despite the air being well below freezing. We will certainly be returning when the weather warms up.

But the purpose of this blog isn’t to recount the adventure Alisha and I went on a few weeks ago. While Nevada has the most thermal springs of any state in the country, it certainly doesn’t have the highest density. Yellowstone National Park is a very well-known example of an area with a high density of thermal springs and other things such as geysers. Yellowstone’s geothermal activity is a little different from that in Nevada, though.

Our nation’s first national park is the site of a supervolcano. As such, Yellowstone contains a large magma chamber that is, in some spots, only a few kilometers below the surface. In non-volcanic continental regions, the depth of magma averages about 35km and in extreme cases can reach 70km below the ground (that’s according to my textbook). Yellowstone is not expected to erupt anytime soon (see also: Yellowstone Volcano Observatory / archive), but the presence of shallow magma allows the groundwater to become heated and returned to the surface very easily. Hot springs heated by a volcanic magma chamber can be found elsewhere around the globe, such as around the volcanoes in the Cascade Mountains.

Unlike Yellowstone, though, Nevada is not volcanically active. It has been in the past, but the only volcanic area currently monitored by the California Volcano Observatory (archive) is a small, dormant volcano near Fallon. As such, most of Nevada’s thermal springs must have formed from a different source. Despite having very low precipitation values, Nevada has numerous aquifers. Much of the state lies within the Great Basin, an area in the Western United States where water doesn’t reach the ocean because of topography. As such, when rivers reach their endpoint, their water either evaporates or sinks deep into the earth.

Even in areas where you have to dig 35km to find magma, the temperature of the ground gets higher the deeper you go. As water from sources like the Truckee and Humboldt Rivers sinks deep underground, it encounters rocks with higher and higher temperatures. The above chart shows how the water moves about under Hot Springs, Arkansas (home of WeatherTogether blogger Nathan Parker). The underground flow demonstrated above is similar to what is seen in Nevada. After the water is heated underground, it is returned to the surface by various fault lines located throughout the state.

These fault lines are extremely important to the development of thermal springs. As the water warms, it expands. The cracks in the crust that form these fault lines provide a conduit for this heated water to expand upward, eventually leaking back out onto the surface.

So how do these thermal springs have an effect on my daily life? Because of the vast number of springs in the state, there has been extensive development in the geothermal energy sector. This renewable source of energy involved drilling wells deep into the earth, allowing heated water and/or steam to rise to the surface. This water and steam causes turbines in the plant to turn and generate electricity.

NV Energy reports (archive) that geothermal energy accounts for 486 megawatts of power being generated in Nevada. The largest geothermal plant in the state, located at McGinness Hills, creates enough energy to power 57,000 homes. According to the Energy Information Administration (archive), geothermal energy makes up 50% of the renewable energy generated in Nevada.

What ways does geology affect your daily life? Share it with us in the comments below! And, if you noticed I made a mistake, please let me know through my contact form. Thanks for reading!