Gan-date: A Monumental Volcanic Cliff
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.
The Exposed Cross-Section of an Ancient Lava Flow
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.
Explore the Natural Wonders of Gan-date Gorge
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.