Gan-date is a towering cliff located at the confluence of the Nigorigawa River and Sawarabi Valley in Ochiai, Osaka Town, Gero City, Gifu Prefecture. The surrounding area is known as Gan-date Gorge.
Gan-date Park provides an excellent vantage point from which to admire this impressive geological formation up close. The park features an observation deck, a shop, and parking facilities, including space for large tour buses.
A 600-meter waterfall-viewing trail runs through the park to Mitsutaki Falls. Along the way, visitors can see a statue of Fudō Myōō, a Buddhist deity associated with the revered monk Enkū.
Continuing approximately two kilometers farther along the forest road leads to Akagane-toyo Falls and Karatani Falls. The surrounding scenery changes with the seasons, from fresh green foliage in spring to brilliant autumn colors. Gan-date Gorge is particularly famous for its fall foliage and has been selected as one of the 33 Best Autumn Foliage Spots in Hida and Mino.
Viewed from the Ontake Panorama Line, the lava formation appears as an expansive, flat-topped green ridge stretching into the distance. This striking landscape has earned it the nickname “the Green Grand Canyon.”
Gan-date is designated a natural monument of Gifu Prefecture. The massive rock face measures approximately 72 meters high and 120 meters wide.
Its surface displays distinctive columnar jointing, a geological feature formed as lava cooled and solidified. The resulting cracks divide the rock into column-like formations, some several dozen centimeters thick, creating the appearance of a wall made of enormous stone pillars.
The cliff represents the exposed end of a lava flow produced by an eruption of Mount Ontake approximately 54,000 years ago. It lies about 17 kilometers downstream from the mountain. The entire flow is known as the Sixth Marishiten Lava Flow and consists of two-pyroxene andesite.
In 2007, when Mount Ontake was selected for inclusion among Japan’s 100 Geological Sites, Gan-date was recognized as part of this significant volcanic landscape.
Gan-date is considered Japan’s largest exposed cross-section of a lava flow formed from andesitic rock approximately 54,000 years ago. Similar rock walls extend for around 17 kilometers upstream, revealing the impressive scale of the ancient volcanic deposit.
Amadori Rock, located along the Neo Falls hiking route, is another striking feature of this landscape. Formed from the same lava flow, it reaches approximately 150 meters in height—about twice the height of Gan-date.
Gan-date was once connected to a smaller formation downstream known as Ko-Gan-date. However, erosion by Sawarabi Valley’s stream separated the two formations, shifting the smaller section approximately 300 meters away.
Gan-date Park combines dramatic volcanic geology, beautiful waterfalls, and seasonal mountain scenery. Visitors can admire the immense lava cliff, follow the walking trail to Mitsutaki Falls, or venture farther into the gorge to discover additional waterfalls.
Whether visiting for its geological significance, spring greenery, or autumn foliage, the park offers a memorable opportunity to experience the remarkable natural landscape at the foot of Mount Ontake.