Soda Dam and Rimstone Pool

October 01, 2005


Provided and copyright by: Rick Scott
Summary authors & editors: Rick Scott

This small pool was formed by the action of a hot spring just a little north of Jemez Springs, New Mexico --- photographed on July 6, 2005. It's inside a small cave that's part of the much larger "Soda Dam," a natural travertine (calcium carbonate) dam that blocks the Jemez River. Water from the hot spring comes from the Valle Caldera, a little to the north, after being heated by hot rocks and magma. This water then flows through a layer of limestone where it collects the calcium carbonate and then deposits it when exposed to the air. In the case of the pool pictured above, the water is dripping from the ceiling, which created a short, squat mound, much the way a stalagmite forms in a limestone cave. A small depression on the top of the young mound acted as a puddle that trapped some of the water. Through dissolution and evaporation, some of the calcium carbonate formed a rim around the edge of this little puddle. Over many years, the mound grew and the little puddle tuned into a little pool with walls made from the deposits. The edge of the pool is referred to as a rimstone dam -- it grows with the pool. The famous formations at the base of Havasu Falls in Arizona were created through a similar process.

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