Last summer I finally had the chance to visit Devils Postpile National Monument in California. While everyone shares their photos of the iconic columnar basalt at the park, a different location caught my attention on the park map: “Soda Springs.”

Driven by curiosity, I wandered to where the Middle Fork of the San Joaquin River passes through Soda Springs Meadow.

View of Soda Springs Meadow.

View of Soda Springs Meadow, looking north. Devils Postpile National Monument, CA. (August 2011) Image (c) C.B. Dawson

View of gas escaping at groundwater spring

Bubbles are caused by gas escaping at mineral spring where groundwater discharges into a gravel bar in the River. Devils Postpile National Monument, CA. (August 2011)

While there, I overheard a tour guide explaining that water levels were too low to see the bubbling springs typically visible at the edges of the river. I wandered down to the edge (in the photo above, on the left bank where people are walking around), and what a treat!

In this area, groundwater discharges into a gravel bar on the west side of the River. The mineral springs occur where gas and water vapor from deep, hot volcanic areas below the Earth’s surface rise up and combine with groundwater.  I took some video, since still images really don’t effectively capture the experience. (Warning: I clearly am in need of a tripod!)

This is not a boiling pool: the water is not hot. The bubbles are primarily carbon dioxide (CO2), similar to the bubbles you see in a carbonated soft drink.  Hence the name “soda” springs! The orange staining visible in some areas is caused when iron in the spring water oxidizes when it is exposed to the air.  I haven’t found any detail on the overall water quality of these particular mineral springs. (There has been  great deal of research into CO2 emissions in the Long Valley Caldera region in general, and a large tree kill-off in the late 1980s nearby on Mammoth Mountain was attributed to elevated CO2 emissions.)


References and Resources

Devils Postpile National Monument – National Park Service official site

Sequoia Natural History Association, 2002, The Story of Devils Postpile – A Land of Volcanic Fire, Glacial Ice, and an Ancient River: Sequoia Natural History Association, 42 p.

U.S. Geological Survey (USGS) California Volcano Observatory, Long Valley Caldera web site: