Hiyama Waterfall is located where Sawauchi River flows over stair-like columnar joints, with an estimated drop of 50 m.
Inside the mudstone that accumulated here, lava forming another rock called dacite flowed through the rock, close to the surface. Most of the lava did not break through to the outer air, instead slowly cooling and hardening inside the mudstone. This is when the pillar-like cracks called columnar joints formed.

Chokai Junior High School in Yurihonjō City formed a “Geosite Exploration Squad” to explore places within the school’s district where the Earth and its nature can be observed. This activity created an opportunity for the local community to learn more about the area, and led to this site being designated as a geopark site.