Kiyotsu Gorge

▶The Birth of Kiyotsu Gorge
About 16 million years ago, volcanic ash from submarine volcanic activity settled on the seafloor. Chemical changes caused it to turn green, forming green tuff*1. About 5 million years ago, magma flowed into the green tuff strata from underground. As it cooled and solidified, it became pyroxene andesite*2, and as it cooled, its volume shrank and formed a structure called columnar joints*3. Later, the earth became more geologically active, the seafloor rose to become mountains on land, and the Kiyotsu River eroded them away, exposing the underground pyroxene andesite columnar joints at the bottom of the valley. As the valley deepened, the present-day Kiyotsu Gorge was formed. The cliffs of Kiyotsu Gorge are made up of bundles of columnar rocks, like a cluster of hexagonal pencils, rather than a single monolithic slab. For that reason, although the rock is hard, it is also brittle and prone to collapse. (See image below)
*1 Tuff: rock formed when volcanic ash hardens.
*2 Pyroxene andesite: a type of volcanic rock formed when magma cools and solidifies. Andesite and basalt are in the same family.
*3 Columnar joints: when magma cools and solidifies, it contracts and forms four- to six-sided column-shaped rock.

▶The History of Kiyotsu Gorge
The existence of the hot springs was already known during the Genroku era, about 300 years ago. From that time on, there were discussions about developing the hot springs, but many issues, including the terrain, prevented any work from being done for a long time.
In 1862 (Bunkyu 2, Edo period), a hot spring resort was established by local residents. In 1941 (Showa 16), the gorge’s scenic beauty and columnar-jointed landscape were recognized as outstanding, and it was designated a national place of scenic beauty and natural monument.
In 1949 (Showa 24), it was designated as part of Jōshin’etsu-kōgen National Park, and the hot spring district was also developed.
In February 1984 (Showa 59), a massive avalanche struck part of the hot spring district, causing many casualties. In July 1988 (Showa 63), a rockfall accident occurred on the Kiyotsu mountain trail along the Kiyotsu River from Kiyotsu Gorge Onsen to Yagisawa, and since then this walkway has been completely closed to the public.

▶How the Gorge Tunnel Came to Be
After the Kiyotsu Gorge mountain trail was closed, local residents and tourists requested that the place where the columnar-jointed gorge scenery is most impressive (Byobu-iwa) be made accessible for viewing. In response, discussions began among the Environment Agency (responsible for national parks), the Agency for Cultural Affairs (responsible for natural monuments), Niigata Prefecture, and the former Nakazato Village (now Tokamachi City).
As a result:
1. Reopening the closed promenade was impossible.
2. Because the rocks are prone to collapse, it would be difficult to develop a safe walkway.
3. As the area is within a national park, constructing large artificial structures that would damage the appearance would not be permitted.
4. Since national parks are intended for use by the public at large, it would not be acceptable to leave such a valuable tourism resource unused.
For these reasons, it was decided to build a “walkway tunnel” as an alternative facility, allowing visitors to safely enjoy the beauty of the gorge without harming the national park’s scenery. Construction of the walkway tunnel began in 1992 (Heisei 4), with Nakazato Village as the project owner. The total construction cost was approximately 2 billion yen. In October 1996 (Heisei 8), the Kiyotsu Gorge Tunnel was opened (the riverside walkway remains closed to this day).

▶Rebirth Through Contemporary Art
More than 20 years after opening, the number of visitors had been declining year by year, falling to around 50,000 annually. To reverse this trend, the tunnel was renovated in conjunction with the Echigo-Tsumari Art Triennale, held once every three years in Tokamachi City and Tsunan Town.
In April 2018, as part of the Echigo-Tsumari Art Triennale 2018, the tunnel facility was renovated and a new entrance facility was added (work title: “Tunnel of Light”).
In April 2021, a new artwork was added at the second observation point as part of the Echigo-Tsumari Art Triennale 2021.
The Kiyotsu Gorge Tunnel is 750 meters long. From its three observation points and the Panorama Station at the tunnel’s end, visitors can enjoy the magnificent beauty of the gorge. In particular, the Panorama Station at the end opens into a fantastical art space where the gorge scenery is reflected and inverted in a water mirror. Enjoy the soft fresh greenery that highlights the gorge’s beauty, the cool clear stream, the vivid autumn foliage, and the winter scenery like a ink wash painting. Display corners placed throughout the tunnel also introduce Kiyotsu Gorge’s four seasons and the natural processes that formed it.