Gandate Gorge is a magnificent rocky canyon, 72 meters high and 120 meters wide, formed around 54 thousand years ago. It was created by the lava that flowed through here following the eruption of Mt. Ontake. It has been designated a Natural Monument of Gifu Prefecture.
The same rocky formation extends upstream for around 16 kilometers, making this the longest continuous lava flow in Japan that is still visible today. Gandate Gorge itself is a cross-section of this lava flow formation.
The streaked pattern seen on the rocky surface is due to a phenomenon called “columnar jointing,” which is caused when lava cools, hardens and separates into column-like shapes.
Gandate Gorge was once connected with a smaller downstream site called Ko-Gandate, literally meaning “little Gandate”; however, water which flowed from nearby Sawaradani Valley for around 300 meters caused erosion which cleaved Gandate Gorge into two, creating Ko-Gandate as a separate area.
From the observatory located on the way to Nigorigo Onsen, visitors can take in the view of this lava flow formation, topped with bands of greenery that seem to stretch endlessly as the rocky formation meanders its way from the panoramic spectacle of Mt. Ontake. It is this landscape that has led to Gandate Gorge being known as the “green Grand Canyon” by the Japanese.

 
[Pet etiquette in the park]
・Be sure to wear a leash.
・Carry feces disposal tools (shoves, plastic bags, etc.) and be sure to take your trash home with you.
・Please refrain from any other behavior that may cause trouble to other users.
・Please note that you may be surprised by the loud noise of the waterfall.