Fraser and Cathy Goff, both geologists, led a trip Sept. 20 to Sulphur Springs on the far side of the Valle Caldera.
Sulphur Springs was once a resort where people bathed in acid waters and mudpots to cure skin ailments. The original structures, built in the 1930s, burned in the 1960s, and the property was then used by those seeking communal living and free love. The property was purchased by the Corbin family and others in the 1980s, and is once again for sale.
Extremely complex geology includes thermal features, cross faults, fumaroles (steam vents), mudpots, and hot and cold acid spring discharges. Water temperatures at the site range from background to boiling.