Lake Oshino - Oshinoko

...First, the Saruhashi lava flow formed two lakes, Lake Utsu and Lake Senoumi. Lake Utsu was further divided into Lake Yamanaka, Lake Oshino, and Lake Kawaguchi by lava flows, and Lake Oshino was filled in to become the Oshino Basin. Lake Motosu was first separated from Senoumi, and was further divided into Lake Saiko and Lake Shojiko by the Aokigahara lava flow caused by the eruption of 864 (Jogan 6).

*Some of the terms mentioned in relation to "Lake Oshino" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…まず，猿橋溶岩流によって宇津湖，剗海（せのうみ）の2湖が形成された。宇津湖はさらに溶岩流によって山中湖，忍野（おしの）湖，河口湖に分けられ，忍野湖は埋積して忍野盆地となった。剗海からはまず本栖湖が分かれ，さらに864年(貞観6)の噴火による青木ヶ原溶岩流で西湖と精進湖に分離した。…

※「忍野湖」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