SODA SPRINGS
Nearby mineral springs are evidence of recent local volcanic activity. The Soda Springs lie on a gravel bar in the San Joaquin River just north of the Postpile. Here, gases driven upward from hot areas deep in the earth combine with ground water to produce cold and highly carbonated mineralized springs. The iron present in Soda Springs water oxidizes on exposure to the atmosphere and stains river gravel a reddish brown.
