The basalt columns at Takachiho Gorge were formed some 270,000 years ago as a result of four eruptions of the Mount Aso volcano. Since, the Gokase River has cut through the columns, creating a narrow, V‑shaped chasm through which beautiful blue-green water flows. Boats float down the four-mile gorge in the shadow of these 300-foot, red-tinted cliffs. The site has been protected as a National Scenic Spot and Natural Monument in Japan since 1934.