01 / Strata
Part of the Cretaceous-Paleogene boundary layerwas found up a Kawaruppu River tributary.
In May 2026, a research group including Tohoku University showed that the K/Pg boundary layer is not at the Mokawaruppu River outcrop long assumed to be one, but in mudstone about 4 km northeast, upstream of a Kawaruppu River tributary. The town museum writes that the old outcrop is a fault fracture zone.
- End of the Cretaceous, about 66 million years ago
- Upstream of a tributary, about 4 km northeast
- Announced in May 2026

