先述の越後妻有地域固有の資源（財産）目録の調査結果より、信濃川の流路の位置・標高の時代的な変化について注目した。現存する段丘上で発見された古信濃川の流路の痕跡と見られる地層から現在の信濃川本流との標高差を推測したところ、信濃川は1万年前には現在より25mほど上空を流れていたことがわかった。信濃川が河岸段丘を形成する過程を、旧中里村に現存する段丘面に見られる侵食、堆積、崩落、土石流、残存岩石などの状況を実寸で表示した。

The Shinano River once flowed 25meters above where it presently flows, 2003

Based on the survey results from the inventory of unique resources (assets) specific to the Echigo-Tsumari region, we focused on the chronological changes in the course and elevation of the Shinano River. By estimating the elevation difference between the current main stream of the Shinano River and the layers identified as traces of the old Shinano River’s course, discovered on the existing terraces, it has been determined that approximately 10,000 years ago, the Shinano River flowed about 25 meters above its current level. The process of river terrace formation by the Shinano River is vividly illustrated through the erosion, sedimentation, collapse, debris flows, and residual rocks observed on the terrace surfaces still present in the former Nakazato Village.