Okuchichibu Mountains

…It is also called Oku-Chichibu Mountains, meaning the inner part of the Chichibu Mountains in the upper reaches of the Arakawa River that runs through Saitama Prefecture. Blessed with natural beauty of steep mountain ridges over 1000m above sea level and deep V-shaped valleys, the geology is made up of sedimentary rocks of the Chichibu Palaeozoic and Mesozoic strata, and there are mountains of igneous rocks such as granite from the prefectural border to the Yamanashi Prefecture side.

*Some of the terminology that refers to the "Oku-Chichibu Mountains" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…埼玉県を貫流する荒川上流部の秩父山地の奥の意味で，奥秩父山地ともいう。標高1000m以上の険しい山稜と深いV字谷の自然美に恵まれ，地質は秩父古生層と中生層の堆積岩よりなり，県境付近から山梨県側にかけては花コウ岩などの火成岩の山もある。…

※「奥秩父山地」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報