Fujioka Historical Museum
Sanbaseki Gorge
Sanbaseki Gorge on the Sanba River contains massive green schist boulders shaped by the river over the ages. They are part of an ancient metamorphic belt exposed by upthrust due to tectonic action. This type of rock is rarely seen since it is normally deep underground.
The boulders are principally found in a 1.5-kilometer stretch of the gorge that has been designated as a national scenic spot and a natural monument. Some of the formations have been given names due to their evocative shapes.
The distinctive color and shapes of Sanba River rocks have made them prized traditional-style garden features for centuries. They have been so extensively quarried for that purpose that this gorge is believed to be one of the only places left in Japan where this type of stone can be found in its natural state.