Bentenjima Island and Ojaura Seashore
Bentenjima Island is a small, sacred islet just off the Ojaura seashore. Its dramatic, craggy rock is punctuated by a red torii gate, which marks the entrance to the shrine on the island. Hakujabenten, the white snake goddess is enshrined here. She is the deity of all that flows, such as water, music, and art. A folk tale describes how snakes in human form arrived on the island and lured away a fisherman’s two daughters; in return, his fortunes prospered. To appease these mythical snakes, worshippers leave eggs at the shrine as offerings.
At low tide, the unusual geology of Bentenjima Island and the Ojaura seashore becomes apparent. You can see how Bentenjima juts up dramatically from the surrounding flat rock, which is composed of alternating layers of mudstone and sandstone. The jagged formations that seem to pierce and rise upwards through the flat bed of rock are the result of seismic activity and tectonic forces. They occur when a ductile, deformable material (a rock that can bend or flow, like clay) penetrates more brittle overlying rocks. This is a type of geological intrusion known as a diapir. A fine-grained sediment has penetrated the mudstone and sandstone along tectonically induced fractures. The mud diapir here is one of the best such examples in Japan.
In both March and August, there are several days when a 3-hour window makes it possible to walk to the island before the tide comes in.
