Iwayaji no Kiriake

Overview

Iwayaji no Kiriake is a tiny yet remarkable slot-like gorge in Nakamura, Okuizumo, Shimane. Its name, meaning a cut-through, comes from the trench-shaped valley that slices through the former grounds of the now-abandoned Iwayaji temple, looking almost as if carved by human hands. Because it lies near a hilltop, where river erosion would normally be unlikely, this deep cleft is geologically precious and was designated a National Natural Monument in 1932.

Highlights

• ●The trench-like gorge that slices through the hillside
• ●A geologically rare deep valley cut near a summit
• ●The erosion drama driven by a hidden fault fracture zone
• ●Its standing as a National Natural Monument since 1932

History

On 25 July 1932 the site was named a National Natural Monument as an unusual erosional landform born near a summit. Its origin long puzzled researchers, but a 2005 survey revealed a hidden fault fracture zone at the valley floor. A soft crushed band, sandwiched between hard granite, is now thought to have been scoured out rapidly by debris flows from extraordinary torrential rain a few hundred to over a thousand years ago. The name Iwayaji recalls the temple that once stood here.

Map

35.1942, 133.1023 · Wikidata

Suggested itinerary

1. 1Drive into the Nakamura area of Okuizumo and follow signs to the trailhead
2. 2Walk the slope path to reach the Kiriake gorge
3. 3Observe the cut-through valley and rock faces and ponder its origin
4. 4Round off the trip touring the rural landscapes and sights of Okuizumo

Did you know?

💡 The name Kiriake, a cut-through, was given because the valley looks as though someone sliced the hill open. In reality it is a natural erosional feature, and a deep valley carved so close to a summit is rare nationwide. Geologists judge it to have formed in a very recent era, making it a site where the terrain may still be changing today.

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