Chichibu Geopark

Basic points

You can see the stratum back from the time when Kochichibuwan (Paleo Chichibu Bay)—which existed in the area of the current Chichibu Basin from roughly 17 million to 15 million years ago—ceased to exist. The conglomerate outcrop is designated as a national natural monument.

When the Sotochichibu Mountains bulged out, and the part that is now the Chichibu Basin settled, the cliffs surrounding the sea had collapsed and accumulated on the eastern edge of the basin. This outcrop had been deposited right after the cliffs had been worn away, so there are still huge rock bodies with a horny shape.