Ishikari River
The geography of the gorge and surrounding area were formed by the eruption of Daisetsuzan Volcanic Group, which occurred around 30,000 years ago. The welded tuff was piled up after the eruption, and it was gradually eroded by the water of the Ishikari River, which currently streams between gorges. Thus, ragged steep cliffs in Sōunkyō were shaped, which range over 24 kilometres. and have a number of joints around 200 metres in height