Sunlight and Swiss Cheese, City of Rocks - Idaho

Autumn near Bath Rock, in the City of Rocks. Panholes like these form in the granite stone over a millennium. Panholes begin as tiny depressions or cracks where water remains for long periods of time. The longer water remains on the granite surface, the greater the dissolution of minerals by acidic water.

city of rocksidahodesert. aspenfallorangegraniteformation